The first Australian gravimetric quasigeoid model with location-specific uncertainty estimates

Science.gov (United States)

Featherstone, W. E.; McCubbine, J. C.; Brown, N. J.; Claessens, S. J.; Filmer, M. S.; Kirby, J. F.

2018-02-01

We describe the computation of the first Australian quasigeoid model to include error estimates as a function of location that have been propagated from uncertainties in the EGM2008 global model, land and altimeter-derived gravity anomalies and terrain corrections. The model has been extended to include Australia's offshore territories and maritime boundaries using newer datasets comprising an additional {˜ }280,000 land gravity observations, a newer altimeter-derived marine gravity anomaly grid, and terrain corrections at 1^' ' }× 1^' ' } resolution. The error propagation uses a remove-restore approach, where the EGM2008 quasigeoid and gravity anomaly error grids are augmented by errors propagated through a modified Stokes integral from the errors in the altimeter gravity anomalies, land gravity observations and terrain corrections. The gravimetric quasigeoid errors (one sigma) are 50-60 mm across most of the Australian landmass, increasing to {˜ }100 mm in regions of steep horizontal gravity gradients or the mountains, and are commensurate with external estimates.

Reference materials characterized for impurities in uranium matrices. An overview and re-evaluation of the NBL CRM 124 series

International Nuclear Information System (INIS)

Buerger, S.; Mathew, K.J.; Mason, P.; Narayanan, U.

2009-01-01

The characterized concentrations of 24 impurity elements in New Brunswick Laboratory (NBL) Certified Reference Material (CRM) 124 were reevaluated. A provisional certificate of analysis was issued in September 1983 based upon the 'as prepared' values (gravimetric mixing). The provisional certificate does not state uncertainties for the characterized values, or estimate the degree of homogeneity. Since release of the provisional certificate of analysis various laboratories have reported analytical results for CRM 124. Based upon the reported data a re-evaluation of the characterized values with an estimate of their uncertainties was performed in this work. An assessment of the degree of homogeneity was included. The overall difference between the re-evaluated values for the 24 impurity elements and the 'as prepared' values from the provisional certificate of analysis is negligible compared to the uncertainties. Therefore, NBL will establish the 'as prepared' values as the certified values and use the derived uncertainties from this work for the uncertainties of the certified values. The traceability of the 'as prepared' values was established by the gravimetric mixing procedure employed during the preparation of the CRM. NBL further recommends a minimum sample size of 1 g of the CRM material to ensure homogeneity. Samples should be dried by heating up to 110 deg C for one hour before use. (author)

Visual estimation versus gravimetric measurement of postpartum blood loss: a prospective cohort study.

Science.gov (United States)

Al Kadri, Hanan M F; Al Anazi, Bedayah K; Tamim, Hani M

2011-06-01

One of the major problems in international literature is how to measure postpartum blood loss with accuracy. We aimed in this research to assess the accuracy of visual estimation of postpartum blood loss (by each of two main health-care providers) compared with the gravimetric calculation method. We carried out a prospective cohort study at King Abdulaziz Medical City, Riyadh, Saudi Arabia between 1 November 2009 and 31 December 2009. All women who were admitted to labor and delivery suite and delivered vaginally were included in the study. Postpartum blood loss was visually estimated by the attending physician and obstetrics nurse and then objectively calculated by a gravimetric machine. Comparison between the three methods of blood loss calculation was carried out. A total of 150 patients were included in this study. There was a significant difference between the gravimetric calculated blood loss and both health-care providers' estimation with a tendency to underestimate the loss by about 30%. The background and seniority of the assessing health-care provider did not affect the accuracy of the estimation. The corrected incidence of postpartum hemorrhage in Saudi Arabia was found to be 1.47%. Health-care providers tend to underestimate the volume of postpartum blood loss by about 30%. Training and continuous auditing of the diagnosis of postpartum hemorrhage is needed to avoid missing cases and thus preventing associated morbidity and mortality.

Comparison of the gravimetric, phenol red, and 14C-PEG-3350 methods to determine water absorption in the rat single-pass intestinal perfusion model

OpenAIRE

Sutton, Steven C.; Rinaldi, M. T. S.; Vukovinsky, K. E.

2001-01-01

This study was undertaken to determine whether the gravimetric method provided an accurate measure of water flux correction and to compare the gravimetric method with methods that employ nonabsorbed markers (eg, phenol red and 14C-PEG-3350). Phenol red, 14C-PEG-3350, and 4-[2-[[2-(6-amino-3-pyridinyl)-2-hydroxyethyl]amino]ethoxy]-methyl ester, (R)-benzene acetic acid (Compound I) were co-perfused in situ through the jejunum of 9 anesthetized rats (single-pass intestinal perfusion [SPIP]). Wat...

Understanding of thermo-gravimetric analysis to calculate number of addends in multifunctional hemi-ortho ester derivatives of fullerenol

International Nuclear Information System (INIS)

Singh, Rachana; Goswami, Thakohari

2011-01-01

Test results for the applicability of existing thermo-gravimetric analysis (TGA) technique to ascertain average number of exohedral chemical attachment in a new class of fullerene dyads consisting of multiple hemi-ortho esters onto fullerenol is presented. Although the method is nicely applicable for higher fullerenol, but homogeneous phase products calculate lower number of addends, whereas, the hetero phase products indicate higher value. Lower value is attributed to either overlapping of thermal events or substituents effects and higher value is the contribution of tetra butyl ammonium hydroxide (TBAH) impurity used as phase transfer catalyst (PTC) in heterogeneous phase reactions. Presence of TBAH impurity is recognized through thermo-gravimetry mass spectrometry (TG-MS) measurement. Appropriate modification of test method to arrive at accurate and precise values of x (total mass contribution due to addends only) and y (total mass contribution due to fullerene plus char yield) are also reported. Successful use of two more different techniques, viz., electron-spray ionization mass spectrometry (ESI-MS) and X-ray photoelectron spectroscopy (XPS), supplement above results. Influences of fullerene and different substituents on thermal behavior of dyads are assessed.

Magnetic impurity coupled to interacting conduction electrons

International Nuclear Information System (INIS)

Schork, T.

1996-01-01

We consider a magnetic impurity which interacts by hybridization with a system of weakly correlated electrons and determine the energy of the ground state by means of a 1/N f expansion. The correlations among the conduction electrons are described by a Hubbard Hamiltonian and are treated to the lowest order in the interaction strength. We find that their effect on the Kondo temperature, T K , in the Kondo limit is twofold: first, the position of the impurity level is shifted due to the reduction of charge fluctuations, which reduces T K . Secondly, the bare Kondo exchange coupling is enhanced as spin fluctuations are enlarged. In total, T K increases. Both corrections require intermediate states beyond the standard Varma-Yafet ansatz. This shows that the Hubbard interaction does not just provide quasiparticles, which hybridize with the impurity, but also renormalizes the Kondo coupling. copyright 1996 The American Physical Society

Coulomb singularity effects in tunnelling spectroscopy of individual impurities

OpenAIRE

Arseyev, P. I.; Maslova, N. S.; Panov, V. I.; Savinov, S. V.

2002-01-01

Non-equilibrium Coulomb effects in resonant tunnelling processes through deep impurity states are analyzed. It is shown that Coulomb vertex corrections to the tunnelling transfer amplitude lead to a power-law singularity in current- voltage characteristics

Chemistry characterization and samples beryllium process impurity determination; Caracterizacao quimica e determinacao de impurezas de amostras de processo de berilio

Energy Technology Data Exchange (ETDEWEB)

Carvalho, Leonel Mathry de

1992-12-01

Brazil is the greatest world producer of beryl (3 Be O.Al{sub 2}O{sub 3}.6SiO{sub 2}) and has recently begun to produce beryllium compounds by means of a pilot plant constructed at Governador Valadares city (Minas Gerais - Brazil). The aim of this work was the determination of trace level impurities and macro constituents in the tenth % range to support analytical control process of plant production and characterization of beryllium compounds. The impurities separations and purification process was developed by two steps procedure. The first one using EDTA complexation has separated and reduced some impurities to less than 1 {mu}g/ml level. In the second one it was used a chelating resin (Chelex 100) and the separation efficiency was about 75 to 97 % related with the element tested. High pure berylium oxide standard was obtained from purification of Be(OH)2. The R X fluorescence presented only traces of Cu and Si < 1 % Fe and Mn, Zn, Ca, Al, Na and S were completely removed. The beryllium content was determined by direct atomic emission spectroscopy in argon plasma (Dcp) and compared with classic gravimetric method as Be O. The results were in agreement (49,2+/-0,2 % and 48,3+/-0,1 % respectively) between 95 % of confidence. A low temperature gravimetric method for beryllium determination was also studied using Oxine with microwave furnace. A total of 24 elements including macro and trace level were determined by Dcp and/or spectrophotometric methods. The Be/B separation was studied using anionic resin in poly alcohols medium. A more detailed study of equilibrium conditions is necessary. This work was realized at Laboratorio de Analise Mineral (LAM) of Comissao Nacional de Energia Nuclear - Rio de Janeiro (CNEN). (author)

Variational method for magnetic impurities in metals: impurity pairs

Energy Technology Data Exchange (ETDEWEB)

Oles, A M [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany, F.R.); Chao, K A [Linkoeping Univ. (Sweden). Dept. of Physics and Measurement Technology

1980-01-01

Applying a variational method to the generalized Wolff model, we have investigated the effect of impurity-impurity interaction on the formation of local moments in the ground state. The direct coupling between the impurities is found to be more important than the interaction between the impurities and the host conduction electrons, as far as the formation of local moments is concerned. Under certain conditions we also observe different valences on different impurities.

Zirconium determination in refractories (gravimetric method)

International Nuclear Information System (INIS)

Capiotto, N.; Narahashi, Y.; Perish, P.G.; Souza, J.R. de

1991-01-01

A gravimetric method for zirconium determination in refractories is described. X-ray fluorescence analysis is also employed in this experiment and considerations about interfering elements are presented. (M.V.M.)

Zirconium determination in refractories (gravimetric method)

International Nuclear Information System (INIS)

Capiotto, N.; Narahashi, Y.; Perish, C.G.; Souza, J.R.

1991-01-01

The zirconium determination in refractories is described, consisting in two separation methods for eliminating the interferences. The formatted product is calcined at 1100 0 C and determined gravimetrically as Zr P z 07. (author)

Gravimetric and titrimetric methods of analysis

International Nuclear Information System (INIS)

Rives, R.D.; Bruks, R.R.

1983-01-01

Gravimetric and titrimetric methods of analysis are considered. Methods of complexometric titration are mentioned, as well as methods of increasing sensitivity in titrimetry. Gravimetry and titrimetry are applied during analysis for traces of geological materials

[Evaluation of the AOAC 985.29 enzimic gravimetric method for determination of dietary fiber in oat and corn grains].

Science.gov (United States)

da Silva, Leila Picolli; Ciocca, Maria de Lourdes Santorio; Furlong, Eliana Badiale

2003-12-01

The precision attributes and use of the enzymatic-gravimetric method of Prosky et al. (1992) (AOAC 985.29) were evaluated using corn (BR 5202 Pampa) and oat (UFRGS 15) samples. The effect of laboratory batches carried out in different days were evaluated in six laboratory batches, using for each material one duplicate for total fiber (FT) determination, one duplicate for insoluble fiber (FI) determination and blank ones for FT and for FI (both in duplicate). In order to characterize repetitive aspects, five other FT and FI determinations added to each sample were evaluated, summing up 11 data. The low coefficients of variation in the first six batches were considered acceptable as an expression of expected total intralaboratory variation. The repetitive of the method was considered good for FT determinations (CVs gravimetric corrections varies with the kind of the sample and is especially influenced by the protein content.

Gravimetric gas determinations for volume calibration

International Nuclear Information System (INIS)

Gibbs, P.W.

1991-01-01

Gravimetric measurements of gases is one of the methods available for calibrating gas volumes. By inputting a known quantity of gas and measuring the resulting pressure and temperature, the system volume can be calculated using gas law principles. Historically, this method has been less accurate due to the difficulty in the mass determination. This difficulty comes from several sources. Two examples are the large tare weight of the gas container relative to the weight of gas and the external volume of the gas container relative to the standards. The application of a gravimetric gas determination to tank volume calibrations at the savannah River Site is discussed. Mass determinations on a 25,00 gram gas container were such that a 1500 gram quantity of gas was routinely determined to within ±0.2 gram at the 99% confidence level. In this paper the weighting design and the methods used to address the difficulties of the mass determination are detailed

Comparison of Potentiometric and Gravimetric Methods for Determination of O/U Ratio

International Nuclear Information System (INIS)

Farida; Windaryati, L; Putro Kasino, P

1998-01-01

Comparison of determination O/U ratio by using potentiometric and gravimetric methods has been done. Those methods are simple, economical and having high precision and accuracy. Determination O/U ratio for UO 2 powder using potentiometric is carried out by adopting the davies-gray method. This technique is based on the redox reaction of uranium species such as U(IV) and U(VI). In gravimetric method,the UO 2 power as a sample is calcined at temperature of 900 C, and the weight of the sample is measured after calcination process. The t-student test show that there are no different result significantly between those methods. However, for low concentration in the sample the potentiometric method has a highed precision and accuracy compare to the gravimetric method. O/U ratio obtained is 2.00768 ± 0,00170 for potentiometric method 2.01089 ± 0,02395 for gravimetric method

Transport of wall released impurities in the limiter scrape-off layer of a tokamak

International Nuclear Information System (INIS)

Claassen, H.A.; Repp, H.

1978-01-01

A collisional theory for the transport of heavy wall released impurities in the plasma scrape-off layer is developed, which to zero order approximation considers electron impact ionization and Coulomb collisions with the plasma ions. Impurity ion convection parallel to the magnetic field and radial drift motion are treated as first order correction terms. The theory, which under certain restrictions to the integral coefficients of the Fokker-Planck collision operator is independent of the special form of the plasma ion distribution, is applied to the calculation of the impurity ion fluxes in the scrape-off layer. Preliminary numerical results are presented for a model plasma ion distribution of the loss ellipse type and a half-maxwellian distribution of the wall released impurity atoms. (Auth.)

Modeling of the Microchemistry for Diffusion of Selected Impurities in Uranium

International Nuclear Information System (INIS)

Kirkpatrick, J. R.; Bullock, J.S. IV

2001-01-01

Unalloyed metallic uranium used in some work done at Y-12 contains small quantities of impurities, the three most significant of which are carbon, iron, and silicon. During metallurgical processing, as the metal cools from a molten condition towards room temperature, the metallic matrix solution becomes supersaturated in each of the impurities whose concentration exceeds the solubility limit. Many impurity atoms form compounds with uranium that precipitate out of the solution, thus creating and growing inclusions. The objective of the present work is to study the distribution of impurity atoms about some of the inclusions, with a view toward examining the effect of the interaction between inclusions on the impurity atom distribution. The method used is time-dependent mass diffusion from the supersaturated solution to the surfaces of the inclusions. Micrographs of metal samples suggest that the inclusions form in successive stages. After each inclusion forms, it begins to draw impurity atoms from its immediate vicinity, thus altering the amounts and distributions of impurity atoms available for formation and growth of later inclusions. In the present work, a one-dimensional spherical approximation was used to simulate inclusions and their regions of influence. A first set of calculations was run to simulate the distribution of impurity atoms about the largest inclusions. Then, a second set of calculations was run to see how the loss of impurity atoms to the largest inclusions might affect the distribution of impurity atoms around the next stage of inclusions. Plots are shown for the estimated distributions of impurity atoms in the region of influence about the inclusions for the three impurities studied. The authors believe that these distributions are qualitatively correct. However, there is enough uncertainty about precisely when inclusions nucleate and begin to grow that one should not put too much reliance on the quantitative results. This work does provide a

Development of an approach to correcting MicroPEM baseline drift.

Science.gov (United States)

Zhang, Ting; Chillrud, Steven N; Pitiranggon, Masha; Ross, James; Ji, Junfeng; Yan, Beizhan

2018-07-01

Fine particulate matter (PM 2.5 ) is associated with various adverse health outcomes. The MicroPEM (RTI, NC), a miniaturized real-time portable particulate sensor with an integrated filter for collecting particles, has been widely used for personal PM 2.5 exposure assessment. Five-day deployments were targeted on a total of 142 deployments (personal or residential) to obtain real-time PM 2.5 levels from children living in New York City and Baltimore. Among these 142 deployments, 79 applied high-efficiency particulate air (HEPA) filters in the field at the beginning and end of each deployment to adjust the zero level of the nephelometer. However, unacceptable baseline drift was observed in a large fraction (> 40%) of acquisitions in this study even after HEPA correction. This drift issue has been observed in several other studies as well. The purpose of the present study is to develop an algorithm to correct the baseline drift in MicroPEM based on central site ambient data during inactive time periods. A running baseline & gravimetric correction (RBGC) method was developed based on the comparison of MicroPEM readings during inactive periods to ambient PM 2.5 levels provided by fixed monitoring sites and the gravimetric weight of PM 2.5 collected on the MicroPEM filters. The results after RBGC correction were compared with those using HEPA approach and gravimetric correction alone. Seven pairs of duplicate acquisitions were used to validate the RBGC method. The percentages of acquisitions with baseline drift problems were 42%, 53% and 10% for raw, HEPA corrected, and RBGC corrected data, respectively. Pearson correlation analysis of duplicates showed an increase in the coefficient of determination from 0.75 for raw data to 0.97 after RBGC correction. In addition, the slope of the regression line increased from 0.60 for raw data to 1.00 after RBGC correction. The RBGC approach corrected the baseline drift issue associated with MicroPEM data. The algorithm developed

Materials identification and surveillance project item evaluation: Items, impure plutonium oxide (ATL27960) and pure plutonium oxide (PEOR3258)

International Nuclear Information System (INIS)

Allen, T.; Appert, Q.; Davis, C.

1997-03-01

In this report, Los Alamos scientists characterize properties relevant to storage of an impure plutonium oxide (74 mass % plutonium) in accordance with the Department of Energy (DOE) standard DOE-STD-3013-96. This oxide is of interest because it is the first impure plutonium oxide sample to be evaluated and it is similar to other materials that must be stored. Methods used to characterize the oxide at certain points during calcination include surface-area analyses, mass loss-on-ignition (LOI) measurements, elemental analysis, moisture-adsorption measurements, and quantitative supercritical-CO 2 extraction of adsorbed water. Significant decreases in the LOI and surface area occurred as the oxide was calcined at progressively increasing temperatures. Studies indicate that supercritical-CO 2 extraction is an effective method for removing adsorbed water from oxides. We extracted the water from powdered oxides (high-purity ZrO 2 , pure PuO 2 , and impure plutonium oxide) using CO 2 at 3000 psi pressure and 75 degrees C, and we quantitatively determined it by using gravimetric and dew-point procedures. The effectiveness of the extraction method is demonstrated by good agreement between the amounts of water extracted from pure zirconium and plutonium dioxides and the mass changes obtained from LOI analyses. However, the amount of moisture (0.025 mass %) extracted from the impure plutonium oxide after it had been calcined at 950 degrees C and stored for a period of months is much less than the LOI value (0.97 mass %). These results imply that the impure plutonium oxide is free of adsorbed water after calcination at 950 degrees C, even though the sample does not satisfy the LOI requirement of <0.50 mass % for storage

The influence of impurities for cross section measurement of {sup 241,243}Am(n,f) reactions

Energy Technology Data Exchange (ETDEWEB)

Kai, Tetsuya; Kobayashi, Katsuhei; Yamamoto, Shuji; Fujita, Yoshiaki; Kimura, Itsuro; Miyoshi, Mitsuharu; Yamamoto, Hideki [Kyoto Univ. (Japan); Shinohara, Nobuo

1997-03-01

The influence of the impurities on the fission cross section measurements for {sup 241}Am and {sup 243}Am has been investigated with the practical results. Following cases have been considered as the influence of impurities; (a) experiments with the {sup 241}Am sample that contains impurities originally, and (b) experiments with the {sup 243}Am sample that contains impurities produced by {alpha}, {beta} decays after the chemical purification. The present study has demonstrated the usefulness of pure samples by the comparison of the experiments using the sample on the market with those using the pure sample processed by the authors. Particularly on the case (b), the correction of the impurity through the periodical measurements was experimentally performed (about 18% around 0.3 eV in 4 weeks after the chemical purification). (author)

Gravimetric method for the determination of diclofenac in pharmaceutical preparations.

Science.gov (United States)

Tubino, Matthieu; De Souza, Rafael L

2005-01-01

A gravimetric method for the determination of diclofenac in pharmaceutical preparations was developed. Diclofenac is precipitated from aqueous solution with copper(II) acetate in pH 5.3 (acetic acid/acetate buffer). Sample aliquots had approximately the same quantity of the drug content in tablets (50 mg) or in ampules (75 mg). The observed standard deviation was about +/- 2 mg; therefore, the relative standard deviation (RSD) was approximately 4% for tablet and 3% for ampule preparations. The results were compared with those obtained with the liquid chromatography method recommended in the United States Pharmacopoeia using the statistical Student's t-test. Complete agreement was observed. It is possible to obtain more precise results using higher aliquots, for example 200 mg, in which case the RSD falls to 1%. This gravimetric method, contrary to what is expected for this kind of procedure, is relatively fast and simple to perform. The main advantage is the absolute character of the gravimetric analysis.

A detailed gravimetric geoid from North America to Eurasia

Science.gov (United States)

Vincent, S. F.; Strange, W. E.; Marsh, J. G.

1972-01-01

A detailed gravimetric geoid of the United States, North Atlantic, and Eurasia, which was computed from a combination of satellite derived and surface gravity data, is presented. The precision of this detailed geoid is + or - 2 to + or - 3 m in the continents but may be in the range of 5 to 7 m in those areas where data is sparse. Comparisons of the detailed gravimetric geoid with results of Rapp, Fischer, and Rice for the United States, Bomford in Europe, and Heiskanen and Fischer in India are presented. Comparisons are also presented with geoid heights from satellite solutions for geocentric station coordinates in North America, the Caribbean, and Europe.

Combined Colorimetric and Gravimetric CMUT Sensor for Detection of Phenylacetone

DEFF Research Database (Denmark)

Mølgaard, Mathias Johannes Grøndahl; Laustsen, Milan; Thygesen, Ida Lysgaard

2017-01-01

The detection of phenylacetone is of interest as it is a common precursor for the synthesis of (meth)amphetamine. Resonant gravimetric sensors can be used to detect the mass and hereby the concentration of a gas while colorimetric arrays typically have an exceptional selectivity to the target...... analyte if the right colorimetric dyes are chosen. We present a sensor system consisting of a Capacitive Micromachined Ultrasonic Transducer (CMUT) and a colorimetric array for detection of phenylacetone. The CMUT is used as a resonant gravimetric gas sensor where the resonance frequency shift due to mass...

Gravimetric Analysis of Uranium in Yellow Cake

International Nuclear Information System (INIS)

Srinuttrakul, Wannee; Jantha, Suwat

2007-08-01

Full text: The gravimetric analysis of uranium in yellow cake is composed of several stages. The analysis takes a long time, which is the disadvantage of this method. However, this gravimetric method provides accurate result for determining the major content of sample. Uranium is the main composition of yellow cake, while Thorium, rare earths and other elements are minor and trace elements. In this work, anion exchange resin was used to separate uranium from other elements to yield highly pure uranium suitable for precipitation. This pure uranium was burnt to U3O8, a form that is stable enough to be weighed. From the optimal condition, the recovery of U3O8 after separating uranium from rare earths and iron is 99.85 ± 0.21%. The application of anion exchange separation was used to analyze uranium in yellow cake obtained from monazite digestion process. It was found that U3O8 in yellow cake is 78.85 ± 2.03%

Trace impurity analyzer

International Nuclear Information System (INIS)

Schneider, W.J.; Edwards, D. Jr.

1979-01-01

The desirability for long-term reliability of large scale helium refrigerator systems used on superconducting accelerator magnets has necessitated detection of impurities to levels of a few ppM. An analyzer that measures trace impurity levels of condensable contaminants in concentrations of less than a ppM in 15 atm of He is described. The instrument makes use of the desorption temperature at an indicated pressure of the various impurities to determine the type of contaminant. The pressure rise at that temperature yields a measure of the contaminant level of the impurity. A LN 2 cryogenic charcoal trap is also employed to measure air impurities (nitrogen and oxygen) to obtain the full range of contaminant possibilities. The results of this detector which will be in use on the research and development helium refrigerator of the ISABELLE First-Cell is described

Impurities in sugar cane and their influence on industrial processing evaluated by nuclear techniques

International Nuclear Information System (INIS)

Bacchi, M.A.; Fernandes, E.A.N.; Ferraz, E.S.B.

1990-01-01

During the cutting and loading operations, impurities, mainly soil, are added to sugar cane in amounts that can impair industrial processing due to excessive wear of metallic members and contamination of juice and bagasse. Mechanization of loading operation has showed a considerable enhancement of the impurity content, leading to the improvement of cane washing technology. Nevertheless, for a correct understanding of the problem and the process optimization, it is necessary and exact and fast quantification of these impurities as well as of its consequences. Nuclear techniques, in special neutron activation analysis, have been proved to be appropriate for estimating soil level in sugar cane, washing process efficiency and wearing of cases and moving parts. (author)

Impact of protein and ligand impurities on ITC-derived protein-ligand thermodynamics.

Science.gov (United States)

Grüner, Stefan; Neeb, Manuel; Barandun, Luzi Jakob; Sielaff, Frank; Hohn, Christoph; Kojima, Shun; Steinmetzer, Torsten; Diederich, François; Klebe, Gerhard

2014-09-01

The thermodynamic characterization of protein-ligand interactions by isothermal titration calorimetry (ITC) is a powerful tool in drug design, giving valuable insight into the interaction driving forces. ITC is thought to require protein and ligand solutions of high quality, meaning both the absence of contaminants as well as accurately determined concentrations. Ligands synthesized to deviating purity and protein of different pureness were titrated by ITC. Data curation was attempted also considering information from analytical techniques to correct stoichiometry. We used trypsin and tRNA-guanine transglycosylase (TGT), together with high affinity ligands to investigate the effect of errors in protein concentration as well as the impact of ligand impurities on the apparent thermodynamics. We found that errors in protein concentration did not change the thermodynamic properties obtained significantly. However, most ligand impurities led to pronounced changes in binding enthalpy. If protein binding of the respective impurity is not expected, the actual ligand concentration was corrected for and the thus revised data compared to thermodynamic properties obtained with the respective pure ligand. Even in these cases, we observed differences in binding enthalpy of about 4kJ⋅mol(-1), which is considered significant. Our results indicate that ligand purity is the critical parameter to monitor if accurate thermodynamic data of a protein-ligand complex are to be recorded. Furthermore, artificially changing fitting parameters to obtain a sound interaction stoichiometry in the presence of uncharacterized ligand impurities may lead to thermodynamic parameters significantly deviating from the accurate thermodynamic signature. Copyright © 2014 Elsevier B.V. All rights reserved.

Measuring intestinal fluid transport in vitro: Gravimetric method versus non-absorbable marker.

Science.gov (United States)

Whittamore, Jonathan M; Genz, Janet; Grosell, Martin; Wilson, Rod W

2016-04-01

The gut sac is a long-standing, widely used in vitro preparation for studying solute and water transport, and calculation of these fluxes requires an accurate assessment of volume. This is commonly determined gravimetrically by measuring the change in mass over time. While convenient this likely under-estimates actual net water flux (Jv) due to tissue edema. We evaluated whether the popular in vivo volume marker [(14)C]-PEG 4000, offers a more representative measure of Jvin vitro. We directly compared these two methods in five teleost species (toadfish, flounder, rainbow trout, killifish and tilapia). Net fluid absorption by the toadfish intestine based on PEG was significantly higher, by almost 4-fold, compared to gravimetric measurements, compatible with the latter under-estimating Jv. Despite this, PEG proved inconsistent for all of the other species frequently resulting in calculation of net secretion, in contrast to absorption seen gravimetrically. Such poor parallelism could not be explained by the absorption of [(14)C]-PEG (typically gravimetric method therefore remains the most reliable measure of Jv and we urge caution in the use of PEG as a volume marker. Copyright © 2016 Elsevier Inc. All rights reserved.

Upper critical magnetic field of superconducting films with magnetic impurities

International Nuclear Information System (INIS)

Lemberger, T.R.

1978-01-01

The upper critical magnetic field, H/sub c2/(T), of In-Mn and Pb-Mn alloy films was measured. H/sub c2/ was determined from the resistance of the films. The results were compared with the theory of Fulde and Maki. This theory assumes that the electron-phonon coupling is weak, and that the interaction between the impurity spins and the conduction electron spins is weak. The theory predicts that the pair-breaking effect of the magnetic impurities is temperature-independent, and that the pair-breaking effects of the magnetic impurities and the applied magnetic field are additive. Furthermore, it predicts explicitly the temperature dependence of H/sub c2/. The temperature dependence of H/sub c2/ for the In-Mn alloy films is well described by the Fulde-Maki theory, despite the moderately strong electron-phonon coupling and the strong interaction between the impurity spins and the conduction electron spins. The temperature dependence of H/sub c2/ for the Pb-Mn alloy films is not well described by the Fulde-Maki theory, probably due to the strong electron-phonon coupling in Pb. However, even without a quantitatively correct theory, one can conclude from the Pb-Mn data that the pair-breaking effect of the magnetic impurities is temperature independent, and that the pair-breaking effects of the magnetic impurities and the applied magnetic field are additive. For some of the Pb-Mn alloy films, there was a region of positive curvature in H/sub c2/(T) near the zero-field transition temperature. This positive curvature is not understood

40 CFR 1065.290 - PM gravimetric balance.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false PM gravimetric balance. 1065.290... balance. (a) Application. Use a balance to weigh net PM on a sample medium for laboratory testing. (b) Component requirements. We recommend that you use a balance that meets the specifications in Table 1 of...

Impurities in a non-axisymmetric plasma: Transport and effect on bootstrap current

Energy Technology Data Exchange (ETDEWEB)

Mollén, A., E-mail: albertm@chalmers.se [Department of Applied Physics, Chalmers University of Technology, Göteborg (Sweden); Max-Planck-Institut für Plasmaphysik, 17491 Greifswald (Germany); Landreman, M. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Smith, H. M.; Helander, P. [Max-Planck-Institut für Plasmaphysik, 17491 Greifswald (Germany); Braun, S. [Max-Planck-Institut für Plasmaphysik, 17491 Greifswald (Germany); German Aerospace Center, Institute of Engineering Thermodynamics, Pfaffenwaldring 38-40, D-70569 Stuttgart (Germany)

2015-11-15

Impurities cause radiation losses and plasma dilution, and in stellarator plasmas the neoclassical ambipolar radial electric field is often unfavorable for avoiding strong impurity peaking. In this work we use a new continuum drift-kinetic solver, the SFINCS code (the Stellarator Fokker-Planck Iterative Neoclassical Conservative Solver) [M. Landreman et al., Phys. Plasmas 21, 042503 (2014)] which employs the full linearized Fokker-Planck-Landau operator, to calculate neoclassical impurity transport coefficients for a Wendelstein 7-X (W7-X) magnetic configuration. We compare SFINCS calculations with theoretical asymptotes in the high collisionality limit. We observe and explain a 1/ν-scaling of the inter-species radial transport coefficient at low collisionality, arising due to the field term in the inter-species collision operator, and which is not found with simplified collision models even when momentum correction is applied. However, this type of scaling disappears if a radial electric field is present. We also use SFINCS to analyze how the impurity content affects the neoclassical impurity dynamics and the bootstrap current. We show that a change in plasma effective charge Z{sub eff} of order unity can affect the bootstrap current enough to cause a deviation in the divertor strike point locations.

A gravimetric simplified method for nucleated marrow cell counting using an injection needle.

Science.gov (United States)

Saitoh, Toshiki; Fang, Liu; Matsumoto, Kiyoshi

2005-08-01

A simplified gravimetric marrow cell counting method for rats is proposed for a regular screening method. After fresh bone marrow was aspirated by an injection needle, the marrow cells were suspended in carbonate buffered saline. The nucleated marrow cell count (NMC) was measured by an automated multi-blood cell analyzer. When this gravimetric method was applied to rats, the NMC of the left and right femurs had essentially identical values due to careful handling. The NMC at 4 to 10 weeks of age in male and female Crj:CD(SD)IGS rats was 2.72 to 1.96 and 2.75 to 1.98 (x10(6) counts/mg), respectively. More useful information for evaluation could be obtained by using this gravimetric method in addition to myelogram examination. However, some difficulties with this method include low NMC due to blood contamination and variation of NMC due to handling. Therefore, the utility of this gravimetric method for screening will be clarified by the accumulation of the data on myelotoxicity studies with this method.

Preliminary study of gravimetric anomalies in the Magallanes-Fagnano fault system, South America

Directory of Open Access Journals (Sweden)

Juan Manuel Alcacer

2018-01-01

Full Text Available The main objective of this research is to recognize several geological structures associated with the shear zones of the MFFS (Magallanes – Fagnano fault system by the analysis and interpretation of gravimetric anomalies. Besides, to compare the gravimetrical response of the cortical blocks that integrate the region under study, which is related to the different morphotectonic domains recognized in the region. This research was developed employing data obtained from World Gravity 1.0, which includes earth and satellite gravity data derived from the EGM2008 model. The study and interpretation of the MFFS from the analysis and processing of the gravimetric data, allowed appreciation of a noticeable correlation with the most superficial cortical structure.

Comparison of macro-gravimetric and micro-colorimetric lipid determination methods.

Science.gov (United States)

Inouye, Laura S; Lotufo, Guiherme R

2006-10-15

In order to validate a method for lipid analysis of small tissue samples, the standard macro-gravimetric method of Bligh-Dyer (1959) [E.G. Bligh, W.J. Dyer, Can. J. Biochem. Physiol. 37 (1959) 911] and a modification of the micro-colorimetric assay developed by Van Handel (1985) [E. Van Handel, J. Am. Mosq. Control Assoc. 1 (1985) 302] were compared. No significant differences were observed for wet tissues of two species of fish. However, limited analysis of wet tissue of the amphipod, Leptocheirusplumulosus, indicated that the Bligh-Dyer gravimetric method generated higher lipid values, most likely due to the inclusion of non-lipid materials. Additionally, significant differences between the methods were observed with dry tissues, with the micro-colorimetric method consistently reporting calculated lipid values greater than as reported by the gravimetric method. This was most likely due to poor extraction of dry tissue in the standard Bligh-Dyer method, as no significant differences were found when analyzing a single composite extract. The data presented supports the conclusion that the micro-colorimetric method described in this paper is accurate, rapid, and minimizes time and solvent use.

Impurity diffusion in transition-metal oxides

International Nuclear Information System (INIS)

Peterson, N.L.

1982-06-01

Intrinsic tracer impurity diffusion measurements in ceramic oxides have been primarily confined to CoO, NiO, and Fe 3 O 4 . Tracer impurity diffusion in these materials and TiO 2 , together with measurements of the effect of impurities on tracer diffusion (Co in NiO and Cr in CoO), are reviewed and discussed in terms of impurity-defect interactions and mechanisms of diffusion. Divalent impurities in divalent solvents seem to have a weak interaction with vacancies whereas trivalent impurities in divalent solvents strongly influence the vacancy concentrations and significantly reduce solvent jump frequencies near a trivalent impurity. Impurities with small ionic radii diffuse more slowly with a larger activation energy than impurities with larger ionic radii for all systems considered in this review. Cobalt ions (a moderate size impurity) diffuse rapidly along the open channels parallel to the c-axis in TiO 2 whereas chromium ions (a smaller-sized impurity) do not. 60 references, 11 figures

Comparison of fine particle measurements from a direct-reading instrument and a gravimetric sampling method.

Science.gov (United States)

Kim, Jee Young; Magari, Shannon R; Herrick, Robert F; Smith, Thomas J; Christiani, David C

2004-11-01

Particulate air pollution, specifically the fine particle fraction (PM2.5), has been associated with increased cardiopulmonary morbidity and mortality in general population studies. Occupational exposure to fine particulate matter can exceed ambient levels by a large factor. Due to increased interest in the health effects of particulate matter, many particle sampling methods have been developed In this study, two such measurement methods were used simultaneously and compared. PM2.5 was sampled using a filter-based gravimetric sampling method and a direct-reading instrument, the TSI Inc. model 8520 DUSTTRAK aerosol monitor. Both sampling methods were used to determine the PM2.5 exposure in a group of boilermakers exposed to welding fumes and residual fuel oil ash. The geometric mean PM2.5 concentration was 0.30 mg/m3 (GSD 3.25) and 0.31 mg/m3 (GSD 2.90)from the DUSTTRAK and gravimetric method, respectively. The Spearman rank correlation coefficient for the gravimetric and DUSTTRAK PM2.5 concentrations was 0.68. Linear regression models indicated that log, DUSTTRAK PM2.5 concentrations significantly predicted loge gravimetric PM2.5 concentrations (p gravimetric PM2.5 concentrations was found to be modified by surrogate measures for seasonal variation and type of aerosol. PM2.5 measurements from the DUSTTRAK are well correlated and highly predictive of measurements from the gravimetric sampling method for the aerosols in these work environments. However, results from this study suggest that aerosol particle characteristics may affect the relationship between the gravimetric and DUSTTRAK PM2.5 measurements. Recalibration of the DUSTTRAK for the specific aerosol, as recommended by the manufacturer, may be necessary to produce valid measures of airborne particulate matter.

Integrable quantum impurity models

International Nuclear Information System (INIS)

Eckle, H.P.

1998-01-01

By modifying some of the local L operators of the algebraic form of the Bethe Ansatz inhomogeneous one dimensional quantum lattice models can be constructed. This fact has recently attracted new attention, the inhomogeneities being interpreted as local impurities. The Hamiltonians of the so constructed one-dimensional quantum models have a nearest neighbour structure except in the vicinity of the local impurities which involve three-site interactions. The pertinent feature of these models is the absence of backscattering at the impurities: the impurities are transparent. (Copyright (1998) World Scientific Publishing Co. Pte. Ltd)

Relation between hyperfine field and lattice location measurements for heavy impurities in iron: influence of radiation damage

International Nuclear Information System (INIS)

Thome, L.; Bernas, H.; Cohen, C.

1978-01-01

The relation between the hyperfine interaction (HFI) and the lattice location of heavy impurities in iron is discussed in the light of results (see companion papers) on 169 Yb, 175 Yb and Au in Fe. A compilation of all known results in Fe and Cu reveals a simple correlation between the difference in atomic radii of implanted and host atoms and the corrected extinction ratio in lattice location experiments. A simple model is developed to account simultaneously for the annealing -and implantation- temperature dependence of the impurity HFI and lattice location in Fe between room temperature and 800K. It is based on existing information concerning the nature and evolution of radiation damage in Fe: impurity evolution is described in terms of a two-stage process involving (i) vacancy migration towards the impurity and (ii) migration of the impurity-vacancy complex, with the latter stage being much faster than the former. Quantitative agreement is found with our experimental results, as well as with results obtained on other impurities in Fe. It is suggested that the model is applicable in all cases where vacancy motion determines impurity evolution

Reduction Of Gravimetric Data Using An Integrated Computer ...

African Journals Online (AJOL)

The rigour of gravimetric data collection, and the non-availability of comprehensive data reduction software that takes care of local peculiarities, have always constituted hindrance to the application of the gravity method of geophysical studies. However, in recent time, the importance of the gravity method in mineral ...

Validation of spectroscopic gas analyzer accuracy using gravimetric standard gas mixtures: impact of background gas composition on CO2 quantitation by cavity ring-down spectroscopy

Science.gov (United States)

Lim, Jeong Sik; Park, Miyeon; Lee, Jinbok; Lee, Jeongsoon

2017-12-01

The effect of background gas composition on the measurement of CO2 levels was investigated by wavelength-scanned cavity ring-down spectrometry (WS-CRDS) employing a spectral line centered at the R(1) of the (3 00 1)III ← (0 0 0) band. For this purpose, eight cylinders with various gas compositions were gravimetrically and volumetrically prepared within 2σ = 0.1 %, and these gas mixtures were introduced into the WS-CRDS analyzer calibrated against standards of ambient air composition. Depending on the gas composition, deviations between CRDS-determined and gravimetrically (or volumetrically) assigned CO2 concentrations ranged from -9.77 to 5.36 µmol mol-1, e.g., excess N2 exhibited a negative deviation, whereas excess Ar showed a positive one. The total pressure broadening coefficients (TPBCs) obtained from the composition of N2, O2, and Ar thoroughly corrected the deviations up to -0.5 to 0.6 µmol mol-1, while these values were -0.43 to 1.43 µmol mol-1 considering PBCs induced by only N2. The use of TPBC enhanced deviations to be corrected to ˜ 0.15 %. Furthermore, the above correction linearly shifted CRDS responses for a large extent of TPBCs ranging from 0.065 to 0.081 cm-1 atm-1. Thus, accurate measurements using optical intensity-based techniques such as WS-CRDS require TPBC-based instrument calibration or use standards prepared in the same background composition of ambient air.

Technical note: Comparison of metal-on-metal hip simulator wear measured by gravimetric, CMM and optical profiling methods

Science.gov (United States)

Alberts, L. Russell; Martinez-Nogues, Vanesa; Baker Cook, Richard; Maul, Christian; Bills, Paul; Racasan, R.; Stolz, Martin; Wood, Robert J. K.

2018-03-01

Simulation of wear in artificial joint implants is critical for evaluating implant designs and materials. Traditional protocols employ the gravimetric method to determine the loss of material by measuring the weight of the implant components before and after various test intervals and after the completed test. However, the gravimetric method cannot identify the location, area coverage or maximum depth of the wear and it has difficulties with proportionally small weight changes in relatively heavy implants. In this study, we compare the gravimetric method with two geometric surface methods; an optical light method (RedLux) and a coordinate measuring method (CMM). We tested ten Adept hips in a simulator for 2 million cycles (MC). Gravimetric and optical methods were performed at 0.33, 0.66, 1.00, 1.33 and 2 MC. CMM measurements were done before and after the test. A high correlation was found between the gravimetric and optical methods for both heads (R 2  =  0.997) and for cups (R 2  =  0.96). Both geometric methods (optical and CMM) measured more volume loss than the gravimetric method (for the heads, p  =  0.004 (optical) and p  =  0.08 (CMM); for the cups p  =  0.01 (optical) and p  =  0.003 (CMM)). Two cups recorded negative wear at 2 MC by the gravimetric method but none did by either the optical method or by CMM. The geometric methods were prone to confounding factors such as surface deformation and the gravimetric method could be confounded by protein absorption and backside wear. Both of the geometric methods were able to show the location, area covered and depth of the wear on the bearing surfaces, and track their changes during the test run; providing significant advantages to solely using the gravimetric method.

Crumpled Nitrogen-Doped Graphene for Supercapacitors with High Gravimetric and Volumetric Performances.

Science.gov (United States)

Wang, Jie; Ding, Bing; Xu, Yunling; Shen, Laifa; Dou, Hui; Zhang, Xiaogang

2015-10-14

Graphene is considered a promising electrochemical capacitors electrode material due to its high surface area and high electrical conductivity. However, restacking interactions between graphene nanosheets significantly decrease the ion-accessible surface area and impede electronic and ionic transfer. This would, in turn, severely hinder the realization of high energy density. Herein, we report a strategy for preparation of few-layer graphene material with abundant crumples and high-level nitrogen doping. The two-dimensional graphene nanosheets (CNG) feature high ion-available surface area, excellent electronic and ion transfer properties, and high packing density, permitting the CNG electrode to exhibit excellent electrochemical performance. In ionic liquid electrolyte, the CNG electrode exhibits gravimetric and volumetric capacitances of 128 F g(-1) and 98 F cm(-3), respectively, achieving gravimetric and volumetric energy densities of 56 Wh kg(-1) and 43 Wh L(-1). The preparation strategy described here provides a new approach for developing a graphene-based supercapacitor with high gravimetric and volumetric energy densities.

Effects of magnetic impurity scattering on superfluid 3He in aerogel

Science.gov (United States)

Aoyama, Kazushi; Ikeda, Ryusuke

2009-02-01

We investigate impurity effects on superfluid 3He in aerogel whose surface is not coated with 4He, different from most experimental situations. In systems with no 4He coating, spins of solid 3He absorbed on the aerogel surface are active and interact with spins of quasiparticles relevant to superfluidity and, for this reason, such an aerogel is treated as magnetic scatterers. It is found that, in the ABM pairing state affected by magnetic scatterings, not only the l-vector but also the d-vector has no long-ranged orientational order, and that the strong-coupling correction due to impurity scatterings is less suppressed than that in the nonmagnetic case, implying an expansion of the A-like phase region.

Effect of impurities and processing on silicon solar cells. Volume 1: Characterization methods for impurities in silicon and impurity effects data base

Science.gov (United States)

Hopkins, R. H.; Davis, J. R.; Rohatgi, A.; Campbell, R. B.; Blais, P. D.; Rai-Choudhury, P.; Stapleton, R. E.; Mollenkopf, H. C.; Mccormick, J. R.

1980-01-01

Two major topics are treated: methods to measure and evaluate impurity effects in silicon and comprehensive tabulations of data derived during the study. Discussions of deep level spectroscopy, detailed dark I-V measurements, recombination lifetime determination, scanned laser photo-response, conventional solar cell I-V techniques, and descriptions of silicon chemical analysis are presented and discussed. The tabulated data include lists of impurity segregation coefficients, ingot impurity analyses and estimated concentrations, typical deep level impurity spectra, photoconductive and open circuit decay lifetimes for individual metal-doped ingots, and a complete tabulation of the cell I-V characteristics of nearly 200 ingots.

Numerical renormalization group calculation of impurity internal energy and specific heat of quantum impurity models

Science.gov (United States)

Merker, L.; Costi, T. A.

2012-08-01

We introduce a method to obtain the specific heat of quantum impurity models via a direct calculation of the impurity internal energy requiring only the evaluation of local quantities within a single numerical renormalization group (NRG) calculation for the total system. For the Anderson impurity model we show that the impurity internal energy can be expressed as a sum of purely local static correlation functions and a term that involves also the impurity Green function. The temperature dependence of the latter can be neglected in many cases, thereby allowing the impurity specific heat Cimp to be calculated accurately from local static correlation functions; specifically via Cimp=(∂Eionic)/(∂T)+(1)/(2)(∂Ehyb)/(∂T), where Eionic and Ehyb are the energies of the (embedded) impurity and the hybridization energy, respectively. The term involving the Green function can also be evaluated in cases where its temperature dependence is non-negligible, adding an extra term to Cimp. For the nondegenerate Anderson impurity model, we show by comparison with exact Bethe ansatz calculations that the results recover accurately both the Kondo induced peak in the specific heat at low temperatures as well as the high-temperature peak due to the resonant level. The approach applies to multiorbital and multichannel Anderson impurity models with arbitrary local Coulomb interactions. An application to the Ohmic two-state system and the anisotropic Kondo model is also given, with comparisons to Bethe ansatz calculations. The approach could also be of interest within other impurity solvers, for example, within quantum Monte Carlo techniques.

The kinetic of mass loss of grades A and B of melted TNT by isothermal and non-isothermal gravimetric methods

Directory of Open Access Journals (Sweden)

Hamid Reza Pouretedal

2018-04-01

Full Text Available The kinetic and activation energy of mass loss of two grades of melted TNT explosive, grade A and grade B, with freezing points of 80.57 and 78.15 °C, respectively, were studied by isothermal and non-isothermal gravimetric methods. In isothermal method, the mass loss of samples in containers of glass and aluminum was followed in temperatures of 80, 90 and 100 °C. The kinetic of the mass loss of the samples in the aluminum container was higher than the kinetic of it in the glass container that can be related to the effects of heat transfer and catalytic of aluminum metal. Also, the presence of impurities in grade B was due to increasing of kinetic of mass loss of it versus grade A. The non-isothermal curves were obtained in range of 30–330 °C at heating rates of 10, 15 and 20 °C⋅min−1. The TG/DTG data were used for determination of activation energy (Ea of mass loss of TNT samples upon degradation by using Ozawa, Kissinger, Ozawa-Flynn-Wall (OFW and Kissinger-Akahira-Sunose (KAS methods as model free methods. The activation energies of grades of A and B of TNT was obtained 99–120 and 66–70 kJ mol−1, respectively. The lower values of activation energy of the degradation reaction of grade B confirm the effect of impurities in the kinetics of mass loss of this grade. Keywords: TNT, Isothermal, Non-isothermal, Kinetic, Mass loss

Determination of sulphur-35 impurity in solutions of phosphorus-32

International Nuclear Information System (INIS)

Rodriguez Pasques, R.H.; Iglicki, F.A; Cittadini, P.E.

1982-01-01

A method has been developed in order to evaluate the activity of sulphur-35 impurity in solutions of phosphorus-32. The procedure is based on the precipitation on benzidine sulphate in acid solution and further purification by dissolving and reprecipitating under appropriate conditions. 35 S beta radiation is measured with and end-window gas counter. A correction for any remaining 32 P is determined by differential absorption through aluminum. (author) [es

Gravimetric and profilometric measurements of the ablation rates of photosensitive polymers at different wavelengths

International Nuclear Information System (INIS)

Dumont, Th.; Bischofberger, R.; Lippert, T.; Wokaun, A.

2005-01-01

The ablation rates of two polyimides (PMDA and DurimidTM) and one triazene polymer were studied by gravimetric (quartz microbalance) and profilometric (profilometer) methods at irradiation wavelengths of 193, 248 and 308 nm. The ablation rates determined by the two methods are discussed in the context of the absorption behavior of the materials. Furthermore, the consistence of the two experimental methods is discussed for the ablation rates of DurimidTM and the triazene polymer. The gravimetric measurements revealed a good correlation between the ablation rate and the absorption properties of the examined materials. The comparison of the gravimetric and the profilometric measurements suggest a significant mass removal, e.g. by formation of gaseous products, prior to the detection of changes in the surface morphology

A study on improvement of measurement capability for gravimetric flowmeter calibrator

International Nuclear Information System (INIS)

Lee, Dong Keun; Park, Jong Ho

2009-01-01

The calibration of flowmeter is a very important procedure to set up traceability from the national or international standards. The uncertainty of flow measurement defines reliability for measurement results. The uncertainty of gravimetric method combines uncertainties of each independent variable, including mass, time, water density, air density and the density of dead weight. In this study, it has been found that the uncertainties of mass and time measurement in the gravimetric method have dominant influence on the total measurement uncertainty. After improvements of a constant head tank and a diverter, the best measurement capability for K-water's calibration facility has been reached less than 0.1%.

Ab initio study of the EFG tensor at Cd impurities in Sc2O3 semiconductor

International Nuclear Information System (INIS)

Munoz, E.L.; Richard, D.; Errico, L.A.; Renteria, M.

2009-01-01

We present an ab initio study of diluted Cd impurities localized at both cation sites of the semiconductor Sc 2 O 3 . The electric-field-gradient (EFG) tensor at Cd impurities located at both cationic sites of the host structure was determined from the calculation of the electronic structure of the doped system. Calculations were performed with the full-potential augmented-plane wave plus local orbitals (APW+lo) method within the framework of the density functional theory. We studied the atomic structural relaxations and the perturbation of the electronic charge density induced by the impurities in the host system in a fully self-consistent way. We showed that the Cd impurity introduces an increase of 8% in the nearest oxygen neighbors bond-lengths, changing the EFG sign for probes located at the asymmetric cation site. The APW+lo predictions for the charged state of the Cd impurity were compared with EFG results existent in the literature, coming from time-differential γ-γ perturbed-angular-correlations experiments performed on 111 Cd-implanted Sc 2 O 3 powder samples. From the excellent agreement between theory and experiment, we can strongly suggest that the Cd acceptor impurities are ionized at room temperature. Finally, we showed that simple calculations like those performed within the point-charge model with antishielding factors do not correctly describe the problem of a Cd impurity in Sc 2 O 3 .

Impurity solitons with quadratic nonlinearities

DEFF Research Database (Denmark)

Clausen, Carl A. Balslev; Torres, Juan P-; Torner, Lluis

1998-01-01

We fmd families of solitary waves mediated by parametric mixing in quadratic nonlinear media that are localized at point-defect impurities. Solitons localized at attractive impurities are found to be dynamically stable. It is shown that localization at the impurity modifies strongly the soliton...

Quartz analysis in gravimetric sampling

International Nuclear Information System (INIS)

Rex, D.A.

1990-01-01

An overview of the methods employed in the assessment of quartz exposure is provided. The principles and some of the problems associated with each method is discussed. The methods reviewed include wet chemical methods, X-ray diffraction and infrared absorption of which the latter two methods are deemed appropriate for analysing quartz on personal gravimetric collected samples. The implications of combining area samples collected over a six month period, and performing only a single quartz analysis rather than separate analyses, are considered. Finally, various options open to mines with regard to their involvement with quartz analysis are also briefly discussed. 35 refs., 6 figs., 1 tab

Impurity-generated non-Abelions

Science.gov (United States)

Simion, G.; Kazakov, A.; Rokhinson, L. P.; Wojtowicz, T.; Lyanda-Geller, Y. B.

2018-06-01

Two classes of topological superconductors and Majorana modes in condensed matter systems are known to date: one in which disorder induced by impurities strongly suppresses topological superconducting gap and is detrimental to Majorana modes, and another where Majorana fermions are protected by a disorder-robust topological superconductor gap. Observation and control of Majorana fermions and other non-Abelions often requires a symmetry of an underlying system leading to a gap in the single-particle or quasiparticle spectra. In semiconductor structures, impurities that provide charge carriers introduce states into the gap and enable conductance and proximity-induced superconductivity via the in-gap states. Thus a third class of topological superconductivity and Majorana modes emerges, in which topological superconductivity and Majorana fermions appear exclusively when impurities generate in-gap states. We show that impurity-enabled topological superconductivity is realized in a quantum Hall ferromagnet, when a helical domain wall is coupled to an s -wave superconductor. As an example of emergence of topological superconductivity in quantum Hall ferromagnets, we consider the integer quantum Hall effect in Mn-doped CdTe quantum wells. Recent experiments on transport through the quantum Hall ferromagnet domain wall in this system indicated a vital role of impurities in the conductance, but left unresolved the question whether impurities preclude generation of Majorana fermions and other non-Abelions in such systems in general. Here, solving a general quantum-mechanical problem of impurity bound states in a system of spin-orbit coupled Landau levels, we demonstrate that impurity-induced Majorana modes emerge at boundaries between topological and conventional superconducting states generated in a domain wall due to proximity to an s superconductor. We consider both short-range disorder and a smooth random potential. The phase diagram of the system is defined by

Phonon-impurity relaxation and acoustic wave absorption in yttrium-aluminium garnet crystals with impurities

International Nuclear Information System (INIS)

Ivanov, S.N.; Kotelyanskij, I.M.; Medved', V.V.

1983-01-01

The experimental results of investigations of the influence of substitution impurities in the yttrium-aluminium garnet lattice on absorption of high-frequency acoustic waves are presented. It is shown that the phonon-impurity relaxation processses affect at most the wave absorption and have resonance character when the acoustic wave interacts with the thermal phonon group in the vicinity of the perturbed part of the phonon spectrum caused by the impurity. The differences of time values between inelastic and elastic thermal phonons relaxations determined from the data on longitudinal and shear waves in pure and impurity garnet crystals are discussed

Divertor experiment for impurity control in DIVA

International Nuclear Information System (INIS)

Nagami, Masayuki

1979-04-01

Divertor actions of controlling the impurities and the transport of impurity ions in the plasma have been investigated in the DIVA device. Following are the results: (1) The radial transport of impurity ions is not described only by neoclassical theory, but it is strongly influenced by anomalous process. Radial diffusion of impurity ions across the whole minor radius is well described by a neoclassical diffusion superposed by the anomalous diffusion for protons. Due to this anomalous process, which spreads the radial density profile of impurity ions, 80 to 90% of the impurity flux in the plasma outer edge is shielded even in a nondiverted discharge. (2) The divertor reduces the impurity flux entering the main plasma by a factor of 2 to 4. The impurity ions shielded by the scrape-off plasma are rapidly guided into the burial chamber with a poloidal excursion time roughly equal to that of the scrape-off plasma. (3) The divertor reduces the impurity ion flux onto the main vacuum chamber by guiding the impurity ions diffusing from the main plasma into the burial chamber, thereby reducing the plasma-wall interaction caused by diffusing impurity ions at the main vacuum chamber. The impurity ions produced in the burial chamber may flow back to the main plasma through the scrape-off layer. However, roughly only 0.3% of the impurity flux into the scrape-off plasma in the burial chamber penetrates into the main plasma due to the impurity backflow. (4) A slight cooling of the scrape-off plasma with light-impurity injection effectively reduces the metal impurity production at the first wall by reducing the potential difference between the plasma and the wall, thereby reducing the accumulation of the metal impurity in the discharge. Radiation cooling by low-Z impurities in the plasma outer edge, which may become an important feature in future large tokamaks both with and without divertor, is numerically evaluated for carbon, oxygen and neon. (author)

Effect of impurity modes with quasilocal and local frequencies on the superconducting transition temperature

International Nuclear Information System (INIS)

Zhernov, A.P.; Malov, Yu.A.; Panova, G.Kh.

1975-01-01

An anisotropic irregular semiconductor is under consideration. It is believed that the effective parameter of the interaction-lambda-which determines electron coupling is less or about 0.5. The Eliashberg integral equation system is solved for T→Tsub(c). A simple analytic expression is obtained for Tsub(c). The character of a varying critical temperature in superconductors with impurity atoms is analyzed in detail. The dependence of the critical temperature on parameters describing the phonon spectrum of an impurity system is investigated. The existence of impurity modes with quasilocal and local frequencies in the phonon spectra can lead both to relatively small and to rather noticeable variations in Tsub(c). The first case is typical of the situation when an impurity atom is practically an isotopic defect. If an impurity atom is very heavy (Msub(I) 1 0 ) or strongly (γ 1 >>γ 0 ) coupled with matrix atoms. A sharp decrease in the effective force constant γ 1 for an impurity atom results in the growth of delta Tsub(c): delta Tsub(c) approximately cγ0/γ 1 (lambda - μsup((0)). On the contrary a rise in the γ 1 value requires a negative correction to Tsub(c), and delta Tsub(c) approximately c/(lambda - μsup((0)), where c - an impurity concentration, μ - matrix element of the Coulomb screened interaction averaged over the Fermi surface and multiplied for the density of normal electron states on the Fermi level. Comparison with experimental data is made. A qualitative description of the Tsub(c) change due to the impurity presence is given for a set of solutions. There is a satisfactory quantitative agreement between calculated and experimental values of delta Tsub(c)

Graphene plasmons: Impurities and nonlocal effects

Science.gov (United States)

Viola, Giovanni; Wenger, Tobias; Kinaret, Jari; Fogelström, Mikael

2018-02-01

This work analyzes how impurities and vacancies on the surface of a graphene sample affect its optical conductivity and plasmon excitations. The disorder is analyzed in the self-consistent Green's function formulation and nonlocal effects are fully taken into account. It is shown that impurities modify the linear spectrum and give rise to an impurity band whose position and width depend on the two parameters of our model, the density and the strength of impurities. The presence of the impurity band strongly influences the electromagnetic response and the plasmon losses. Furthermore, we discuss how the impurity-band position can be obtained experimentally from the plasmon dispersion relation and discuss this in the context of sensing.

Low Z impurity transport in tokamaks

International Nuclear Information System (INIS)

Hawryluk, R.J.; Suckewer, S.; Hirshman, S.P.

1978-10-01

Low Z impurity transport in tokamaks was simulated with a one-dimensional impurity transport model including both neoclassical and anomalous transport. The neoclassical fluxes are due to collisions between the background plasma and impurity ions as well as collisions between the various ionization states. The evaluation of the neoclassical fluxes takes into account the different collisionality regimes of the background plasma and the impurity ions. A limiter scrapeoff model is used to define the boundary conditions for the impurity ions in the plasma periphery. In order to account for the spectroscopic measurements of power radiated by the lower ionization states, fluxes due to anomalous transport are included. The sensitivity of the results to uncertainties in rate coefficients and plasma parameters in the periphery are investigated. The implications of the transport model for spectroscopic evaluation of impurity concentrations, impurity fluxes, and radiated power from line emission measurements are discussed

The impurity transport in HT-6B tokamak

International Nuclear Information System (INIS)

Huang Rong; Xie Jikang; Li Linzhong; He Yexi; Wang Shuya; Deng Chuanbao; Li Guoxiang; Qiu Lijian

1992-06-01

The quasi-stationary profiles of the impurity ionization stages in HT-6B tokamak were determined by monitoring the VUV (vacuum ultraviolet) and visible line emissions from impurities. An impurity transport code was set up. The impurity transport coefficients and other parameters of impurities in that device were simulated and determined. From the measurement of impurity emission profiles and simulation analysis, it is concluded that the impurity confinement is improved and the impurity recycling is reduced by the slow magnetic compression. Some characteristics of impurity transport in that device are also discussed

Power balance for impurity seeded ergodic divertor discharges in Tore Supra

Energy Technology Data Exchange (ETDEWEB)

Reichle, R.; Vallet, J.C.; Basiuk, V.; Chantant, M.; Giannella, R.; Guirlet, R.; Mitteau, R

1999-10-15

The main emphasis of the present contribution is the search for independent indications concerning local radiation enhancement in the vicinity of target plates by the application of the power-balance analysis to impurity seeded discharges and the use of spatially resolved calorimetry. All methods confirm the existence of an important local radiation enhancement in front of target objects. Their torlly localised nature and the lack of short scale toroidal resolution of the bolometers cause an underestimate of the radiation. Observed corrective factors for radiative divertor discharges range between 1.1 and 1.6 depending on the density. the impurity seeded discharges show during the impurity injection a reduction of this factor which can be explained by the radiation distribution becoming toroidally more symmetric due to larger ionisation lengths. The consistency of the results seems to validate the assumption of a fall off length of the radiation of 40 cm as used for the radiation extrapolation from the outboard calorimetry. The localised extra radiation falling onto one individual neutralizer is about 1 kW. This should be compared with spectroscopic radiation measurements and modelling to see whether there is room for charge exchange neutrals to be important. (authors)

Power balance for impurity seeded ergodic divertor discharges in Tore Supra

International Nuclear Information System (INIS)

Reichle, R.; Vallet, J.C.; Basiuk, V.; Chantant, M.; Giannella, R.; Guirlet, R.; Mitteau, R.

1999-01-01

The main emphasis of the present contribution is the search for independent indications concerning local radiation enhancement in the vicinity of target plates by the application of the power-balance analysis to impurity seeded discharges and the use of spatially resolved calorimetry. All methods confirm the existence of an important local radiation enhancement in front of target objects. Their toroidally localised nature and the lack of short scale toroidal resolution of the bolometers cause an underestimate of the radiation. Observed corrective factors for radiative divertor discharges range between 1.1 and 1.6 depending on the density. the impurity seeded discharges show during the impurity injection a reduction of this factor which can be explained by the radiation distribution becoming toroidally more symmetric due to larger ionisation lengths. The consistency of the results seems to validate the assumption of a fall off length of the radiation of 40 cm as used for the radiation extrapolation from the outboard calorimetry. The localised extra radiation falling onto one individual neutralizer is about 1 kW. This should be compared with spectroscopic radiation measurements and modelling to see whether there is room for charge exchange neutrals to be important. (authors)

Impurity gettering in semiconductors

Science.gov (United States)

Sopori, Bhushan L.

1995-01-01

A process for impurity gettering in a semiconductor substrate or device such as a silicon substrate or device. The process comprises hydrogenating the substrate or device at the back side thereof with sufficient intensity and for a time period sufficient to produce a damaged back side. Thereafter, the substrate or device is illuminated with electromagnetic radiation at an intensity and for a time period sufficient to cause the impurities to diffuse to the back side and alloy with a metal there present to form a contact and capture the impurities. The impurity gettering process also can function to simultaneously passivate defects within the substrate or device, with the defects likewise diffusing to the back side for simultaneous passivation. Simultaneously, substantially all hydrogen-induced damage on the back side of the substrate or device is likewise annihilated. Also taught is an alternate process comprising thermal treatment after hydrogenation of the substrate or device at a temperature of from about 500.degree. C. to about 700.degree. C. for a time period sufficient to cause the impurities to diffuse to the damaged back side thereof for subsequent capture by an alloying metal.

Spectrophotometric, potentiometric, and gravimetric determination of lanthanides with peri-dihydroxynaphthindenone

International Nuclear Information System (INIS)

Hassan, S.S.M.; Mahmoud, W.H.

1982-01-01

Sensitive and reasonably selective methods are described for the spectrophotometric, potentiometric, and gravimetric determination of lanthanides using peri-dihydroxynaphthindenone as a novel chromogenic and precipitating reagent. The reagent forms a stable 1:2 (metal:reagent) type of complex with light lanthanides at pH 2-7 in 1:1 ethanol-water mixture. Low metal concentrations ( 4 L mol -1 cm -1 ) which obey Beer's law. Quantitative precipitation of the complexes from metal solutions of concentrations > 100 μg/mL permits both gravimetric quantitation by igniting the precipitates to the metal oxides and potentiometric titration of the excess reagent. Results with an average recovery of 98% (standard deviation 0.7%) are obtainable for 0.1 μg to 200 mg of all light lanthanides. Many foreign ions naturally occurring or frequently associated with lanthanides do not interfere or can be tolerated

Impurity-induced moments in underdoped cuprates

International Nuclear Information System (INIS)

Khaliullin, G.; Kilian, R.; Krivenko, S.; Fulde, P.

1997-01-01

We examine the effect of a nonmagnetic impurity in a two-dimensional spin liquid in the spin-gap phase, employing a drone-fermion representation of spin-1/2 operators. The properties of the local moment induced in the vicinity of the impurity are investigated and an expression for the nuclear-magnetic-resonance Knight shift is derived, which we compare with experimental results. Introducing a second impurity into the spin liquid an antiferromagnetic interaction between the moments is found when the two impurities are located on different sublattices. The presence of many impurities leads to a screening of this interaction as is shown by means of a coherent-potential approximation. Further, the Kondo screening of an impurity-induced local spin by charge carriers is discussed. copyright 1997 The American Physical Society

The effect of dielectric constant on binding energy and impurity self-polarization in a GaAs-Ga1- x Al x As spherical quantum dot

Science.gov (United States)

Mese, A. I.; Cicek, E.; Erdogan, I.; Akankan, O.; Akbas, H.

2017-03-01

The ground state, 1s, and the excited state, 2p, energies of a hydrogenic impurity in a GaAs-Ga1- x Al x As spherical quantum dot, are computed as a function of the donor positions. We study how the impurity self-polarization depends on the location of the impurity and the dielectric constant. The excited state anomalous impurity self-polarization in the quantum dot is found to be present in the absence of any external influence and strongly depends on the impurity position and the radius of the dot. Therefore, the excited state anomalous impurity self-polarization can give information about the impurity position in the system. Also, the variation of E_{b1s} and E_{b2p} with the dielectric constant can be utilized as a tool for finding out the correct dielectric constant of the dot material by measuring the 1s or 2p state binding energy for a fixed dot radius and a fixed impurity position.

Accuracy criteria recommended for the certification of gravimetric coal-mine-dust samplers

International Nuclear Information System (INIS)

Bowman, J.D.; Bartley, D.L.; Breuer, G.M.; Doemeny, L.J.; Murdock, D.J.

1984-07-01

Procedures for testing bias and precision of gravimetric coal-mine-dust sampling units are reviewed. Performance criteria for NIOSH certification of personal coal-mine dust samplers are considered. The NIOSH criterion is an accuracy of 25% at the 95% confidence interval. Size distributions of coal-mine-dust are discussed. Methods for determining size distributions are described. Sampling and sizing methods are considered. Cyclone parameter estimation is discussed. Bias computations for general sampling units are noted. Recommended procedures for evaluating bias and precision of gravimetric coal mine dust personal samplers are given. The authors conclude that when cyclones are operated at lower rates, the NIOSH accuracy criteria can be met

Impurities in uranium process solutions

International Nuclear Information System (INIS)

Boydell, D.W.

1980-01-01

Several uranium purification circuits are presented in tabular form together with the average major impurity levels associated with each. The more common unit operations in these circuits, namely strong- and weak-base ion-exchange, solvent extraction and the precipitation of impurities are then discussed individually. Particular attention is paid to the effect and removal of impurities in each of these four unit operations. (author)

Role of four-fermion interaction and impurity in the states of two-dimensional semi-Dirac materials.

Science.gov (United States)

Wang, Jing

2018-03-28

We study the effects of four-fermion interaction and impurity on the low-energy states of 2D semi-Dirac materials by virtue of the unbiased renormalization group approach. The coupled flow equations that govern the energy-dependent evolutions of all correlated interaction parameters are derived after taking into account one-loop corrections from the interplay between four-fermion interaction and impurity. Whether and how four-fermion interaction and impurity influence the low-energy properties of 2D semi-Dirac materials are discreetly explored and addressed attentively. After carrying out the standard renormalization group analysis, we find that both trivial insulating and nontrivial semimetal states are qualitatively stable against all four kinds of four-fermion interactions. However, while switching on both four-fermion interaction and impurity, certain insulator-semimetal phase transitions and the distance of Dirac nodal points can be respectively induced and modified due to their strong interplay and intimate competition. Moreover, several non-Fermi liquid behaviors that deviate from the conventional Fermi liquids are exhibited at the lowest-energy limit.

Gravimetric dust sampling for control purposes and occupational dust sampling.

CSIR Research Space (South Africa)

Unsted, AD

1997-02-01

Full Text Available Prior to the introduction of gravimetric dust sampling, konimeters had been used for dust sampling, which was largely for control purposes. Whether or not absolute results were achievable was not an issue since relative results were used to evaluate...

Gravimetric determination of beryllium in the presence of transition metals

International Nuclear Information System (INIS)

Morozova, S.S.; Nikitina, L.V.; Dyatlova, N.M.; Serebryakova, G.V.; Vol'nyagina, A.N.

1976-01-01

A new organic reagent, nitrolotrimethylphosphonic acid (H 6 L), is proposed for gravimetric determination of beryllium. This complexone forms with Be hardly soluble complexes in a wide pH range. The separated complex has a composition Be 5 (HL) 2 x10H 2 O. To elucidate the possibility of determining Be in the presence of transition metals, often accompanying beryllium in alloys, interaction of cations of these metals with H 6 L at different pH has been studied potentiometrically. It has been established that at pH=1.1 in the presence of masking reagent (diethylentriaminopentacetic acid) Be can be determined when zinc, copper, chromium, cobalt, nickel, iron, manganese and cadmium are present. Gravimetric method of determining Be with the help of H 6 L has been developed. The weight form is obtained by drying the precipitate which reduces considerably the time of analysis and the error of determination

Neo-classical impurity transport

International Nuclear Information System (INIS)

Stringer, T.E.

The neo-classical theory for impurity transport in a toroidal plasma is outlined, and the results discussed. A general account is given of the impurity behaviour and its dependence on collisionality. The underlying physics is described with special attention to the role of the poloidal rotation

Gravimetric determination of the iodine number of carbon black

International Nuclear Information System (INIS)

Murphy, L.J. Jr.

1991-01-01

This paper discusses a gravimetric method for the determination of the iodine adsorption number of carbon black. It comprises determining the concentration of an accurately weighed iodine blank solution by adding a standardized titrant to the iodine solution until a titration endpoint is reached and determining the concentration of the iodine solution by accurately weighing the amount of the standardized titrant necessary to reach the endpoint, accurately weighing an amount of carbon black and adding an appropriate amount of an accurately weighed portion of the iodine solution, equilibrating the carbon black-iodine solution mixture, adding the standardized titrant to an accurately weighed portion of the supernatant from the carbon black-iodine mixture until a titration endpoint is reached and determining the concentration of the supernatant by accurately weighing the amount of the standardized titrant necessary to reach the endpoint, wherein the titration endpoint of the supernatant is obtained using an indicating and a reference electrode, and calculating the iodine adsorption number of the carbon black based on the gravimetrically determined concentration of the titrant, the iodine solution, and the supernatant

Measuring and controlling method for organic impurities

International Nuclear Information System (INIS)

Aizawa, Motohiro; Igarashi, Hiroo

1995-01-01

The present invention concerns measurement and control for organic impurities contained in ultrapurified water for use in a nuclear power plant. A specimen containing organic impurities leached out of anionic exchange resins and cationic exchange resins is introduced to an organic material decomposing section to decompose organic impurities into organic carbon and other decomposed products. Sulfate ions, nitrate ions, nitrite ions and carbon dioxide are produced by the decomposition of the organic impurities. As a next step, carbon dioxide in the decomposed products is separated by deaerating with a nitrogen gas or an argon gas and then a TOC concentration is measured by a non-dispersion-type infrared spectrometer. Further, a specimen from which carbon dioxide was separated is introduced to a column filled with ion exchange resins and, after concentrating inorganic ion impurities, the inorganic ion impurities are identified by using a measuring theory of an ion chromatographic method of eluting and separating inorganic ion impurities and detecting them based on the change of electroconductivity depending on the kinds of the inorganic ion impurities. Organic impurities can be measured and controlled, to improve the reliability of water quality control. (N.H.)

Dynamical impurity problems

International Nuclear Information System (INIS)

Emery, V.J.; Kivelson, S.A.

1993-01-01

In the past few years there has been a resurgence of interest in dynamical impurity problems, as a result of developments in the theory of correlated electron systems. The general dynamical impurity problem is a set of conduction electrons interacting with an impurity which has internal degrees of freedom. The simplest and earliest example, the Kondo problem, has attracted interest since the mid-sixties not only because of its physical importance but also as an example of a model displaying logarithmic divergences order by order in perturbation theory. It provided one of the earliest applications of the renormalization group method, which is designed to deal with just such a situation. As we shall see, the antiferromagnetic Kondo model is controlled by a strong-coupling fixed point, and the essence of the renormalization group solution is to carry out the global renormalization numerically starting from the original (weak-coupling) Hamiltonian. In these lectures, we shall describe an alternative route in which we identify an exactly solvable model which renormalizes to the same fixed point as the original dynamical impurity problem. This approach is akin to determining the critical behavior at a second order phase transition point by solving any model in a given universality class

Dynamical impurity problems

Energy Technology Data Exchange (ETDEWEB)

Emery, V.J. [Brookhaven National Lab., Upton, NY (United States); Kivelson, S.A. [California Univ., Los Angeles, CA (United States). Dept. of Physics

1993-12-31

In the past few years there has been a resurgence of interest in dynamical impurity problems, as a result of developments in the theory of correlated electron systems. The general dynamical impurity problem is a set of conduction electrons interacting with an impurity which has internal degrees of freedom. The simplest and earliest example, the Kondo problem, has attracted interest since the mid-sixties not only because of its physical importance but also as an example of a model displaying logarithmic divergences order by order in perturbation theory. It provided one of the earliest applications of the renormalization group method, which is designed to deal with just such a situation. As we shall see, the antiferromagnetic Kondo model is controlled by a strong-coupling fixed point, and the essence of the renormalization group solution is to carry out the global renormalization numerically starting from the original (weak-coupling) Hamiltonian. In these lectures, we shall describe an alternative route in which we identify an exactly solvable model which renormalizes to the same fixed point as the original dynamical impurity problem. This approach is akin to determining the critical behavior at a second order phase transition point by solving any model in a given universality class.

Gravimetric study on the western edge of the Rio de La Plata craton

International Nuclear Information System (INIS)

Rame, G; Miro, R

2010-01-01

This work is about the gravimetric study on the western edge of the Rio de la Plata craton which belongs to the Gondwana fragment in the south of Brazil, Uruguay and central eastern of Argentina. The work consisted of a survey of 332 gravimetric and topographic stations extended from the western edge of the Sierra Chica de Cordoba up to 200 km east on the pampas. The gravity values observed (gobs) were obtained using a LaCoste §Rom berg gravimeter G-961 and 200T Sodin both with 0.01 mGal, referred to IGSN71 (International Gravity Standardization Net 1971) network

The geothermal gradient map of Central Tunisia: Comparison with structural, gravimetric and petroleum data

Science.gov (United States)

Dhia, Hamed Ben

1987-10-01

Five hundred and fifty temperature values, initially measured as either bottom-hole temperatures (BHT) or drill-stem tests (DST), from 98 selected petroleum exploration wells form the basis of a geothermal gradient map of central Tunisia. A "global-statistical" method was employed to correct the BHT measurements, using the DST as references. The geothermal gradient ranges from 23° to 49°C/km. Comparison of the geothermal gradient with structural, gravimetric and petroleum data indicates that: (1) the general trend of the geothermal gradient curves reflects the main structural directions of the region, (2) zones of low and high geothermal gradient are correlated with zones of negative and positive Bouguer anomalies and (3) the five most important oil fields of central Tunisia are located near the geothermal gradient curve of 40° C/km. Such associations could have practical importance in petroleum exploration, but their significance must first be established through further investigation and additional data.

Identification and characterization of potential impurities of donepezil.

Science.gov (United States)

Krishna Reddy, K V S R; Moses Babu, J; Kumar, P Anil; Chandrashekar, E R R; Mathad, Vijayavitthal T; Eswaraiah, S; Reddy, M Satyanarayana; Vyas, K

2004-09-03

Five unknown impurities ranging from 0.05 to 0.2% in donepezil were detected by a simple isocratic reversed-phase high performance liquid chromatography (HPLC). These impurities were isolated from crude sample of donepezil using isocratic reversed-phase preparative high performance liquid chromatography. Based on the spectral data (IR, NMR and MS), the structures of these impurities were characterised as 5,6-dimethoxy-2-(4-pyridylmethyl)-1-indanone (impurity I), 4-(5,6-dimethoxy-2,3-dihydro-1H-2-indenylmethyl) piperidine (impurity II), 2-(1-benzyl-4-piperdylmethyl)-5,6-dimethoxy-1-indanol (impurity III) 1-benzyl-4(5,6-dimethoxy-2,3-dihydro-1H-2-indenylmethyl) piperidine (impurity IV) and 1,1-dibenzyl-4(5,6-dimethoxy-1-oxo-2,3-dihydro-2H-2-indenylmethyl)hexahydropyridinium bromide (impurity V). The synthesis of these impurities and their formation was discussed.

Decomposition of Copper (II) Sulfate Pentahydrate: A Sequential Gravimetric Analysis.

Science.gov (United States)

Harris, Arlo D.; Kalbus, Lee H.

1979-01-01

Describes an improved experiment of the thermal dehydration of copper (II) sulfate pentahydrate. The improvements described here are control of the temperature environment and a quantitative study of the decomposition reaction to a thermally stable oxide. Data will suffice to show sequential gravimetric analysis. (Author/SA)

Impurity Induced Phase Competition and Supersolidity

Science.gov (United States)

Karmakar, Madhuparna; Ganesh, R.

2017-12-01

Several material families show competition between superconductivity and other orders. When such competition is driven by doping, it invariably involves spatial inhomogeneities which can seed competing orders. We study impurity-induced charge order in the attractive Hubbard model, a prototypical model for competition between superconductivity and charge density wave order. We show that a single impurity induces a charge-ordered texture over a length scale set by the energy cost of the competing phase. Our results are consistent with a strong-coupling field theory proposed earlier in which superconducting and charge order parameters form components of an SO(3) vector field. To discuss the effects of multiple impurities, we focus on two cases: correlated and random distributions. In the correlated case, the CDW puddles around each impurity overlap coherently leading to a "supersolid" phase with coexisting pairing and charge order. In contrast, a random distribution of impurities does not lead to coherent CDW formation. We argue that the energy lowering from coherent ordering can have a feedback effect, driving correlations between impurities. This can be understood as arising from an RKKY-like interaction, mediated by impurity textures. We discuss implications for charge order in the cuprates and doped CDW materials such as NbSe2.

The impurity transport in HT-6M tokamak

International Nuclear Information System (INIS)

Xu Wei; Wan Baonian; Xie Jikang

2003-01-01

The space-time profile of impurities has been measured with a multichannel visible spectroscopic detect system and UV rotation-mirror system in the HT-6M tokamak. An ideal impurity transport code has been used to simulate impurities (carbon and oxygen) behaviour during the OHM discharge. The profiles of impurities diffusion and convection coefficient, impurities ion densities in different ionized state, loss power density and effective charge number have been derived. The impurity behaviour during low-hybrid current drive has also been analyzed, the results show that the confinement of particles, impurities and energy has been improved, and emission power and effective charge number have been reduced

Precise and efficient evaluation of gravimetric quantities at arbitrarily scattered points in space

Science.gov (United States)

Ivanov, Kamen G.; Pavlis, Nikolaos K.; Petrushev, Pencho

2017-12-01

Gravimetric quantities are commonly represented in terms of high degree surface or solid spherical harmonics. After EGM2008, such expansions routinely extend to spherical harmonic degree 2190, which makes the computation of gravimetric quantities at a large number of arbitrarily scattered points in space using harmonic synthesis, a very computationally demanding process. We present here the development of an algorithm and its associated software for the efficient and precise evaluation of gravimetric quantities, represented in high degree solid spherical harmonics, at arbitrarily scattered points in the space exterior to the surface of the Earth. The new algorithm is based on representation of the quantities of interest in solid ellipsoidal harmonics and application of the tensor product trigonometric needlets. A FORTRAN implementation of this algorithm has been developed and extensively tested. The capabilities of the code are demonstrated using as examples the disturbing potential T, height anomaly ζ , gravity anomaly Δ g , gravity disturbance δ g , north-south deflection of the vertical ξ , east-west deflection of the vertical η , and the second radial derivative T_{rr} of the disturbing potential. After a pre-computational step that takes between 1 and 2 h per quantity, the current version of the software is capable of computing on a standard PC each of these quantities in the range from the surface of the Earth up to 544 km above that surface at speeds between 20,000 and 40,000 point evaluations per second, depending on the gravimetric quantity being evaluated, while the relative error does not exceed 10^{-6} and the memory (RAM) use is 9.3 GB.

On impurities transport in a tokamak

International Nuclear Information System (INIS)

Rozhanskij, V.A.

1980-01-01

Transport of impurity ions is analitically analized in the case when main plasma is in plateau or banana regimes but impurity ions - in the Pfirsch-Schlutter mode. It is shown that in the large region of parameters the impUrity transport represents a drift in a p oloidal electric field, averaged from magnetic surface with provision for disturbance of concentration on it. Therefore, transport velocity does not depend on Z value and impurity type, as well as collision frequency both in the plateau and banana regimes. A value of flows is determined by the value of poloidal rotation velocity. At the rotation velocity corresponding to the electric field directed from the centre to periphery impurities are thrown out of a discharge, in the reverse case the flow is directed inside. Refusal from the assumption that Zsub(eff) > approximately 2, does not considerably change the results of work. The approach developed in the process of work can be applied to the case when impurity ions are in the plateau or banana modes

Mechanisms of impurity diffusion in rutile

International Nuclear Information System (INIS)

Peterson, N.L.; Sasaki, J.

1984-01-01

Tracer diffusion of 46 Sc, 51 Cr, 54 Mn, 59 Fe, 60 Co, 63 Ni, and 95 Zr, was measured as functions of crystal orientation, temperature, and oxygen partial pressure in rutile single crystals using the radioactive tracer sectioning technique. Compared to cation self-diffusion, divalent impurities (e.g., Co and Ni) diffuse extremely rapidly in TiO 2 and exhibit a large anisotropy in the diffusion behavior; divalent-impurity diffusion parallel to the c-axis is much larger than it is perpendicular to the c-axis. The diffusion of trivalent impurity ions (Sc and Cr) and tetravalent impurity ions (Zr) is similar to cation self-diffusion, as a function of temperature and of oxygen partial pressure. The divalent impurity ions Co and Ni apparently diffuse as interstitial ions along open channels parallel to the c-axis. The results suggest that Sc, Cr, and Zr ions diffuse by an interstitialcy mechanism involving the simultaneous and cooperative migration of tetravalent interstitial titanium ions and the tracer-impurity ions. Iron ions diffused both as divalent and as trivalent ions. 8 figures

Impurity production and transport at limiters

International Nuclear Information System (INIS)

Matthews, G.F.

1989-01-01

This paper concentrates on the description and evaluation of experiments on the DITE tokamak. These are designed to characterise the processes involved in the production and transport of neutral and ionised impurities near carbon limiters. The need for good diagnostics in the scrape-off layer is highlighted. Langmuir probes are used to provide input data for models of impurity production at limiters. Observations of the radial profiles of carbon and oxygen impurities are compared with the code predictions. Changeover experiments involving hydrogen and helium plasmas are used as a means for investigating the role of the atomic physics and chemistry. The impurity control limiter (ICL) experiment is described which shows how geometry plays an important role in determining the spatial distributions of the neutral and ionised carbon. New diagnostics are required to study the flux and charge state distribution of impurities in the boundary. Preliminary results from an in-situ plasma ion mass-spectrometer are presented. The role of oxygen and the importance of evaluating the wall sources of impurity are emphasised. (orig.)

Some technical details concerning a new method of gravimetric-seismic inversion

DEFF Research Database (Denmark)

Strykowski, Gabriel

1999-01-01

In this paper a number of technical details related to a new method of gravimetric-seismic inversion, which is still under development, are explained. Although the present contribution aims on providing general statements on how to formulate and solve complex gravimetric-seismic modeling; problems......, the inspiration comes from the practical modeling problems in the area of Jutland peninsula (Denmark). More specifically, the methodological aspects of the proposed inversion method are illustrated on a problem of 3D modeling of the intra crustal intrusion associated with the Silkeborg Gravity High. The existing...... refraction seismic profile locates the source of the anomaly in depths 10 km - 18 km. In an earlier publication, (Strykowski, 1998), and for the same test area, a method of complex geological stripping is described. The present contribution is a continuation of this paper in the direction of inversion...

Ab initio study of the EFG tensor at Cd impurities in Sc{sub 2}O{sub 3} semiconductor

Energy Technology Data Exchange (ETDEWEB)

Munoz, E.L.; Richard, D. [Departamento de Fisica and IFLP (CONICET-UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC 67, 1900 La Plata (Argentina); Errico, L.A. [Departamento de Fisica and IFLP (CONICET-UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC 67, 1900 La Plata (Argentina); Universidad Nacional del Noroeste Bonaerense (UNNOBA), Monteagudo 2772, Pergamino, CP 2700 Buenos Aires (Argentina); Renteria, M., E-mail: renteria@fisica.unlp.edu.a [Departamento de Fisica and IFLP (CONICET-UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC 67, 1900 La Plata (Argentina)

2009-10-01

We present an ab initio study of diluted Cd impurities localized at both cation sites of the semiconductor Sc{sub 2}O{sub 3}. The electric-field-gradient (EFG) tensor at Cd impurities located at both cationic sites of the host structure was determined from the calculation of the electronic structure of the doped system. Calculations were performed with the full-potential augmented-plane wave plus local orbitals (APW+lo) method within the framework of the density functional theory. We studied the atomic structural relaxations and the perturbation of the electronic charge density induced by the impurities in the host system in a fully self-consistent way. We showed that the Cd impurity introduces an increase of 8% in the nearest oxygen neighbors bond-lengths, changing the EFG sign for probes located at the asymmetric cation site. The APW+lo predictions for the charged state of the Cd impurity were compared with EFG results existent in the literature, coming from time-differential gamma-gamma perturbed-angular-correlations experiments performed on {sup 111}Cd-implanted Sc{sub 2}O{sub 3} powder samples. From the excellent agreement between theory and experiment, we can strongly suggest that the Cd acceptor impurities are ionized at room temperature. Finally, we showed that simple calculations like those performed within the point-charge model with antishielding factors do not correctly describe the problem of a Cd impurity in Sc{sub 2}O{sub 3}.

Entanglement entropy of a three-spin-interacting spin chain with a time-reversal-breaking impurity at one boundary

Science.gov (United States)

Nag, Tanay; Rajak, Atanu

2018-04-01

We investigate the effect of a time-reversal-breaking impurity term (of strength λd) on both the equilibrium and nonequilibrium critical properties of entanglement entropy (EE) in a three-spin-interacting transverse Ising model, which can be mapped to a p -wave superconducting chain with next-nearest-neighbor hopping and interaction. Importantly, we find that the logarithmic scaling of the EE with block size remains unaffected by the application of the impurity term, although, the coefficient (i.e., central charge) varies logarithmically with the impurity strength for a lower range of λd and eventually saturates with an exponential damping factor [˜exp(-λd) ] for the phase boundaries shared with the phase containing two Majorana edge modes. On the other hand, it receives a linear correction in term of λd for an another phase boundary. Finally, we focus to study the effect of the impurity in the time evolution of the EE for the critical quenching case where the impurity term is applied only to the final Hamiltonian. Interestingly, it has been shown that for all the phase boundaries, contrary to the equilibrium case, the saturation value of the EE increases logarithmically with the strength of impurity in a certain regime of λd and finally, for higher values of λd, it increases very slowly dictated by an exponential damping factor. The impurity-induced behavior of EE might bear some deep underlying connection to thermalization.

Investigations of impurity control in JET using fuelling, and interpretation of experiments using the LIM impurity code

International Nuclear Information System (INIS)

Gondhalekar, A.; Stangeby, P.C.; Elder, J.D.

1994-01-01

Inhibition of contamination of the plasma core in JET by edge impurities during high power heating of deuterium plasmas in limiter configuration using fuelling is demonstrated. By injecting deuterium gas during heating, in the presence of a much larger recycling deuterium flux, a reduction of more than a factor of 2 was effected in n z (0)/Φ z , the ratio of central impurity density to impurity influx at the plasma edge. The reduction in n z (0) was obtained without much effect on peak electron temperature and density. Reduction of plasma contamination by gas fuelling was observed also when hot spots formed on the limiter, a condition that without simultaneous gas fuelling culminated in runaway plasma contamination. Detailed analysis of the experiments is undertaken with the purpose of identifying the processes by which plasma contamination was inhibited, employing standard limiter plasma contamination modelling. Processes which might produce the observed impurity inhibiting effects of gas injection include: (a) reduction in impurity production at the limiter; (b) increase in impurity screening in the scrape-off layer; (c) increase in radial impurity transport at the plasma edge; (d) increase in average deuteron flow velocity to the limiter along the scrape-off layer. These are examined in detail using the Monte Carlo limiter impurity transport code LIM. Bearing in mind that uncertainties exist both in the choice of appropriate modelling assumptions to be used and in the measurement of required edge plasma parameters, changes in n z (0)/Φ z by a factor of 2 are at the limit of the present modelling capability. However, comparison between LIM code simulations and measurements of plasma impurity content indicate that the standard limiter plasma contamination model may not be adequate and that other processes need to be added in order to be able to describe the experiments in JET. (author). 24 refs, 2 figs, 8 tabs

Void growth suppression by dislocation impurity atmospheres

International Nuclear Information System (INIS)

Weertman, J.; Green, W.V.

1976-01-01

A detailed calculation is given of the effect of an impurity atmosphere on void growth under irradiation damage conditions. Norris has proposed that such an atmosphere can suppress void growth. The hydrostatic stress field of a dislocation that is surrounded by an impurity atmosphere was found and used to calculate the change in the effective radius of a dislocation line as a sink for interstitials and vacancies. The calculation of the impurity concentration in a Cottrell cloud takes into account the change in hydrostatic pressure produced by the presence of the cloud itself. It is found that void growth is eliminated whenever dislocations are surrounded by a condensed atmosphere of either oversized substitutional impurity atoms or interstitial impurity atoms. A condensed atmosphere will form whenever the average impurity concentration is larger than a critical concentration

Moessbauer Studies of Implanted Impurities in Solids

CERN Multimedia

2002-01-01

Moessbauer studies were performed on implanted radioactive impurities in semiconductors and metals. Radioactive isotopes (from the ISOLDE facility) decaying to a Moessbauer isotope were utilized to investigate electronic and vibrational properties of impurities and impurity-defect structures. This information is inferred from the measured impurity hyperfine interactions and Debye-Waller factor. In semiconductors isoelectronic, shallow and deep level impurities have been implanted. Complex impurity defects have been produced by the implantation process (correlated damage) or by recoil effects from the nuclear decay in both semiconductors and metals. Annealing mechanisms of the defects have been studied. \\\\ \\\\ In silicon amorphised implanted layers have been recrystallized epitaxially by rapid-thermal-annealing techniques yielding highly supersaturated, electrically-active donor concentrations. Their dissolution and migration mechanisms have been investigated in detail. The electronic configuration of Sb donors...

Low-Z impurities in PLT

International Nuclear Information System (INIS)

Hinnov, E.; Suckewer, S.; Bol, K.; Hawryluk, R.; Hosea, J.; Meservey, E.

1977-11-01

Low-Z impurities concentrations (oxygen and carbon) have been measured in different discharges in PLT. The contribution to Z/sub eff/, influx rates and radiation losses by oxygen and carbon were obtained. An inverse correlation was found between the low-Z impurity density (and also the edge ion temperature) and the high-Z impurity (tungsten) density. A one-dimensional computer transport model has been used to calculate the spatial profiles of different oxygen and carbon ionization states. This model predicts that fully stripped oxygen and carbon ions should exist near the plasma periphery

Uncertainty associated with assessing semen volume: are volumetric and gravimetric methods that different?

Science.gov (United States)

Woodward, Bryan; Gossen, Nicole; Meadows, Jessica; Tomlinson, Mathew

2016-12-01

The World Health Organization laboratory manual for the examination of human semen suggests that an indirect measurement of semen volume by weighing (gravimetric method) is more accurate than a direct measure using a serological pipette. A series of experiments were performed to determine the level of discrepancy between the two methods using pipettes and a balance which had been calibrated to a traceable standard. The median weights of 1.0ml and 5.0ml of semen were 1.03 g (range 1.02-1.05 g) and 5.11 g (range 4.95-5.16 g), respectively, suggesting a density for semen between 1.03g and 1.04 g/ml. When the containers were re-weighed after the removal of 5.0 ml semen using a serological pipette, the mean residual loss was 0.12 ml (120 μl) or 0.12 g (median 100 μl, range 70-300 μl). Direct comparison of the volumetric and gravimetric methods in a total of 40 samples showed a mean difference of 0.25ml (median 0.32 ± 0.67ml) representing an error of 8.5%. Residual semen left in the container by weight was on average 0.11 g (median 0.10 g, range 0.05-0.19 g). Assuming a density of 1 g/ml then the average error between volumetric and gravimetric methods was approximately 8% (p gravimetric measurement of semen volume. Laboratories may therefore prefer to provide in-house quality assurance data in order to be satisfied that 'estimating' semen volume is 'fit for purpose' as opposed to assuming a lower uncertainty associated with the WHO recommended method.

Comparison of Metal-on-Metal Hip Simulator Wear Measured by Gravimetric, CMM and Optical Profiling Methods

OpenAIRE

Alberts, Larry Russell; Martinez-Nogues, Vanesa; Cook, Richard; Maul, Christian; Bills, Paul J.; Racasan, Radu; Stolz, Martin; Wood, Robert J. K.

2018-01-01

Simulation of wear in artificial joint implants is critical for evaluating implant designs and materials. Traditional protocols employ the gravimetric method to determine the loss of material by measuring the weight of the implant components before and after various test intervals and after the completed test. However, the gravimetric method cannot identify the location, area coverage or maximum depth of the wear and it has difficulties with proportionally small weight changes in relatively h...

Erosion of water-based cements evaluated by volumetric and gravimetric methods.

Science.gov (United States)

Nomoto, Rie; Uchida, Keiko; Momoi, Yasuko; McCabe, John F

2003-05-01

To compare the erosion of glass ionomer, zinc phosphate and polycarboxylate cements using volumetric and gravimetric methods. For the volumetric method, the eroded depth of cement placed in a cylindrical cavity in PMMA was measured using a dial gauge after immersion in an eroding solution. For the gravimetric method, the weight of the residue of a solution in which a cylindrical specimen had been immersed was measured. 0.02 M lactic acid solution (0.02 M acid) and 0.1 M lactic acid/sodium lactate buffer solution (0.1 M buffer) were used as eroding solutions. The pH of both solutions was 2.74 and the test period was 24 h. Ranking of eroded depth and weight of residue was polycarboxylate>zinc phosphate>glass ionomers. Differences in erosion were more clearly defined by differences in eroded depth than differences in weight of residue. In 0.02 M acid, the erosion of glass ionomer using the volumetric method was effected by the hygroscopic expansion. In 0.1 M buffer, the erosion for polycarboxylate and zinc phosphate using the volumetric method was much greater than that using the gravimetric method. This is explained by cryo-SEM images which show many holes in the surface of specimens after erosion. It appears that zinc oxide is dissolved leaving a spongy matrix which easily collapses under the force applied to the dial gauge during measurement. The volumetric method that employs eroded depth of cement using a 0.1 M buffer solution is able to quantify erosion and to make material comparisons.

Impurity energy level in the Haldane gap

International Nuclear Information System (INIS)

Wang Wei; Lu Yu

1995-11-01

An impurity bond J' in a periodic 1D antiferromagnetic spin 1 chain with exchange J is considered. Using the numerical density matrix renormalization group method, we find an impurity energy level in the Haldane gap, corresponding to a bound state near the impurity bond. When J' J. The impurity level appears only when the deviation dev = (J'- J)/J' is greater than B c , which is close to 0.3 in our calculation. (author). 15 refs, 4 figs

Multi-impurity polarons in a dilute Bose-Einstein condensate

International Nuclear Information System (INIS)

Santamore, D H; Timmermans, Eddy

2011-01-01

We describe the ground state of a large, dilute, neutral atom Bose-Einstein condensate (BEC) doped with N strongly coupled mutually indistinguishable, bosonic neutral atoms (referred to as ‘impurity’) in the polaron regime where the BEC density response to the impurity atoms remains significantly smaller than the average density of the surrounding BEC. We find that N impurity atoms with N ≠ 1 can self-localize at a lower value of the impurity-boson interaction strength than a single impurity atom. When the ‘bare’ short-range impurity-impurity repulsion does not play a significant role, the self-localization of multiple bosonic impurity atoms into the same single particle orbital (which we call co-self-localization) is the nucleation process of the phase separation transition. When the short-range impurity-impurity repulsion successfully competes with co-self-localization, the system may form a stable liquid of self-localized single impurity polarons. (paper)

Collision of impurities with Bose–Einstein condensates

Science.gov (United States)

Lingua, F.; Lepori, L.; Minardi, F.; Penna, V.; Salasnich, L.

2018-04-01

Quantum dynamics of impurities in a bath of bosons is a long-standing problem in solid-state, plasma, and atomic physics. Recent experimental and theoretical investigations with ultracold atoms have focused on this problem, studying atomic impurities immersed in an atomic Bose–Einstein condensate (BEC) and for various relative coupling strengths tuned by the Fano‑Feshbach resonance technique. Here, we report extensive numerical simulations on a closely related problem: the collision between a bosonic impurity consisting of a few 41K atoms and a BEC of 87Rb atoms in a quasi one-dimensional configuration and under a weak harmonic axial confinement. For small values of the inter-species interaction strength (regardless of its sign), we find that the impurity, which starts from outside the BEC, simply causes the BEC cloud to oscillate back and forth, but the frequency of oscillation depends on the interaction strength. For intermediate couplings, after a few cycles of oscillation the impurity is captured by the BEC, and strongly changes its amplitude of oscillation. In the strong interaction regime, if the inter-species interaction is attractive, a local maximum (bright soliton) in the BEC density occurs where the impurity is trapped; if, instead, the inter-species interaction is repulsive, the impurity is not able to enter the BEC cloud and the reflection coefficient is close to one. However, if the initial displacement of the impurity is increased, the impurity is able to penetrate the cloud, leading to the appearance of a moving hole (dark soliton) in the BEC.

Calculation of impurity poloidal rotation from measured poloidal asymmetries in the toroidal rotation of a tokamak plasma

Energy Technology Data Exchange (ETDEWEB)

Chrystal, C. [University of California-San Diego, La Jolla, California 92186-5608 (United States); Burrell, K. H.; Groebner, R. J.; Kaplan, D. H. [General Atomics, San Diego, California 92186-5608 (United States); Grierson, B. A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States)

2012-10-15

To improve poloidal rotation measurement capabilities on the DIII-D tokamak, new chords for the charge exchange recombination spectroscopy (CER) diagnostic have been installed. CER is a common method for measuring impurity rotation in tokamak plasmas. These new chords make measurements on the high-field side of the plasma. They are designed so that they can measure toroidal rotation without the need for the calculation of atomic physics corrections. Asymmetry between toroidal rotation on the high- and low-field sides of the plasma is used to calculate poloidal rotation. Results for the main impurity in the plasma are shown and compared with a neoclassical calculation of poloidal rotation.

Calculation of impurity poloidal rotation from measured poloidal asymmetries in the toroidal rotation of a tokamak plasma.

Science.gov (United States)

Chrystal, C; Burrell, K H; Grierson, B A; Groebner, R J; Kaplan, D H

2012-10-01

To improve poloidal rotation measurement capabilities on the DIII-D tokamak, new chords for the charge exchange recombination spectroscopy (CER) diagnostic have been installed. CER is a common method for measuring impurity rotation in tokamak plasmas. These new chords make measurements on the high-field side of the plasma. They are designed so that they can measure toroidal rotation without the need for the calculation of atomic physics corrections. Asymmetry between toroidal rotation on the high- and low-field sides of the plasma is used to calculate poloidal rotation. Results for the main impurity in the plasma are shown and compared with a neoclassical calculation of poloidal rotation.

Crustal thickness of Antarctica estimated using data from gravimetric satellites

Science.gov (United States)

Llubes, Muriel; Seoane, Lucia; Bruinsma, Sean; Rémy, Frédérique

2018-04-01

Computing a better crustal thickness model is still a necessary improvement in Antarctica. In this remote continent where almost all the bedrock is covered by the ice sheet, seismic investigations do not reach a sufficient spatial resolution for geological and geophysical purposes. Here, we present a global map of Antarctic crustal thickness computed from space gravity observations. The DIR5 gravity field model, built from GOCE and GRACE gravimetric data, is inverted with the Parker-Oldenburg iterative algorithm. The BEDMAP products are used to estimate the gravity effect of the ice and the rocky surface. Our result is compared to crustal thickness calculated from seismological studies and the CRUST1.0 and AN1 models. Although the CRUST1.0 model shows a very good agreement with ours, its spatial resolution is larger than the one we obtain with gravimetric data. Finally, we compute a model in which the crust-mantle density contrast is adjusted to fit the Moho depth from the CRUST1.0 model. In East Antarctica, the resulting density contrast clearly shows higher values than in West Antarctica.

Determination of Impurities of Atrazine by HPLP-MS

Energy Technology Data Exchange (ETDEWEB)

Canping, Pan [Department of Applied Chemistry, China Agricultural University Beijing (China)

2009-07-15

The determination of the main impurities of the herbicide atrazine by GC/FID, GC/MS and LC/MS is described. The most relevant technical impurities were synthesized and characterized by IR and UV spectroscopy as well. The impurity profiles of different technical grade formulated products were tested and the typical impurities identified. (author)

Influence of iron impurities on defected graphene

Energy Technology Data Exchange (ETDEWEB)

Faccio, Ricardo; Pardo, Helena [Centro NanoMat, Cryssmat-Lab, DETEMA, Polo Tecnológico de Pando, Facultad de Química, Universidad de la República, Cno. Saravia s/n, CP 91000 Pando (Uruguay); Centro Interdisciplinario en Nanotecnología, Química y Física de Materiales, Espacio Interdisciplinario, Universidad de la República, Montevideo (Uruguay); Araújo-Moreira, Fernando M. [Materials and Devices Group, Department of Physics, Universidade Federal de São Carlos, SP 13565-905 (Brazil); Mombrú, Alvaro W., E-mail: amombru@fq.edu.uy [Centro NanoMat, Cryssmat-Lab, DETEMA, Polo Tecnológico de Pando, Facultad de Química, Universidad de la República, Cno. Saravia s/n, CP 91000 Pando (Uruguay); Centro Interdisciplinario en Nanotecnología, Química y Física de Materiales, Espacio Interdisciplinario, Universidad de la República, Montevideo (Uruguay)

2015-03-01

Highlights: • The interaction among a multivacancy graphene system and iron impurities is studied. • The studied iron impurities were single atom and tetrahedral and octahedral clusters. • DFT calculations using the VASP code were performed. • The embedding of Fe affects the structure and electronic behavior in the graphene. • Half metal or semimetal behavior can be obtained, depending on the Fe impurities. - Abstract: The aim of this work is to study the interaction of selected iron cluster impurities and a multivacancy graphene system, in terms of the structural distortion that the impurities cause as well as their magnetic response. While originally, the interaction has been limited to vacancies and isolated metallic atoms, in this case, we consider small iron clusters. This study was undertaken using Density Functional Theory (DFT) calculations. The influence of the iron impurities in the electronic structure of the vacant graphene system is discussed. The main conclusion of this work is that the presence of iron impurities acts lowering the magnetic signal due to the occurrence of spin pairing between carbon and iron, instead of enhancing the possible intrinsic carbon magnetism.

Influence of iron impurities on defected graphene

International Nuclear Information System (INIS)

Faccio, Ricardo; Pardo, Helena; Araújo-Moreira, Fernando M.; Mombrú, Alvaro W.

2015-01-01

Highlights: • The interaction among a multivacancy graphene system and iron impurities is studied. • The studied iron impurities were single atom and tetrahedral and octahedral clusters. • DFT calculations using the VASP code were performed. • The embedding of Fe affects the structure and electronic behavior in the graphene. • Half metal or semimetal behavior can be obtained, depending on the Fe impurities. - Abstract: The aim of this work is to study the interaction of selected iron cluster impurities and a multivacancy graphene system, in terms of the structural distortion that the impurities cause as well as their magnetic response. While originally, the interaction has been limited to vacancies and isolated metallic atoms, in this case, we consider small iron clusters. This study was undertaken using Density Functional Theory (DFT) calculations. The influence of the iron impurities in the electronic structure of the vacant graphene system is discussed. The main conclusion of this work is that the presence of iron impurities acts lowering the magnetic signal due to the occurrence of spin pairing between carbon and iron, instead of enhancing the possible intrinsic carbon magnetism

Impurity bubbles in a BEC

Science.gov (United States)

Timmermans, Eddy; Blinova, Alina; Boshier, Malcolm

2013-05-01

Polarons (particles that interact with the self-consistent deformation of the host medium that contains them) self-localize when strongly coupled. Dilute Bose-Einstein condensates (BECs) doped with neutral distinguishable atoms (impurities) and armed with a Feshbach-tuned impurity-boson interaction provide a unique laboratory to study self-localized polarons. In nature, self-localized polarons come in two flavors that exhibit qualitatively different behavior: In lattice systems, the deformation is slight and the particle is accompanied by a cloud of collective excitations as in the case of the Landau-Pekar polarons of electrons in a dielectric lattice. In natural fluids and gases, the strongly coupled particle radically alters the medium, e.g. by expelling the host medium as in the case of the electron bubbles in superfluid helium. We show that BEC-impurities can self-localize in a bubble, as well as in a Landau-Pekar polaron state. The BEC-impurity system is fully characterized by only two dimensionless coupling constants. In the corresponding phase diagram the bubble and Landau-Pekar polaron limits correspond to large islands separated by a cross-over region. The same BEC-impurity species can be adiabatically Feshbach steered from the Landau-Pekar to the bubble regime. This work was funded by the Los Alamos LDRD program.

Impurity bound states in mesoscopic topological superconducting loops

Science.gov (United States)

Jin, Yan-Yan; Zha, Guo-Qiao; Zhou, Shi-Ping

2018-06-01

We study numerically the effect induced by magnetic impurities in topological s-wave superconducting loops with spin-orbit interaction based on spin-generalized Bogoliubov-de Gennes equations. In the case of a single magnetic impurity, it is found that the midgap bound states can cross the Fermi level at an appropriate impurity strength and the circulating spin current jumps at the crossing point. The evolution of the zero-energy mode can be effectively tuned by the located site of a single magnetic impurity. For the effect of many magnetic impurities, two independent midway or edge impurities cannot lead to the overlap of zero modes. The multiple zero-energy modes can be effectively realized by embedding a single Josephson junction with impurity scattering into the system, and the spin current displays oscillatory feature with increasing the layer thickness.

Hydrogenic impurity in double quantum dots

International Nuclear Information System (INIS)

Wang, X.F.

2007-01-01

The ground state binding energy and the average interparticle distances for a hydrogenic impurity in double quantum dots with Gaussian confinement potential are studied by the variational method. The probability density of the electron is calculated, too. The dependence of the binding energy on the impurity position is investigated for GaAs quantum dots. The result shows that the binding energy has a minimum as a function of the distance between the two quantum dots when the impurity is located at the center of one quantum dot or at the center of the edge of one quantum dot. When the impurity is located at the center of the two dots, the binding energy decreases monotonically

Models for impurity effects in tokamaks

International Nuclear Information System (INIS)

Hogan, J.T.

1980-03-01

Models for impurity effects in tokamaks are described with an emphasis on the relationship between attainment of high β and impurity problems. We briefly describe the status of attempts to employ neutral beam heating to achieve high β in tokamaks and propose a qualitative model for the mechanism by which heavy metal impurities may be produced in the startup phase of the discharge. We then describe paradoxes in impurity diffusion theory and discuss possible resolutions in terms of the effects of large-scale islands and sawtooth oscillations. Finally, we examine the prospects for the Zakharov-Shafranov catastrophe (long time scale disintegration of FCT equilibria) in the context of present and near-term experimental capability

Device for removing impurities from liquid metals

International Nuclear Information System (INIS)

Naito, Kesahiro; Yokota, Norikatsu; Shimoyashiki, Shigehiro; Takahashi, Kazuo; Ishida, Tomio.

1984-01-01

Purpose: To attain highly reliable and efficient impurity removal by forming temperature distribution the impurity removing device thereby providing the function of corrosion product trap, nuclear fission product trap and cold trap under the conditions suitable to the impurity removing materials. Constitution: The impurity removing device comprises a container containing impurity removing fillers. The fillers comprise material for removing corrosion products, material for removing nuclear fission products and material for removing depositions from liquid sodium. The positions for the respective materials are determined such that the materials are placed under the temperature conditions easy to attain their function depending on the temperature distribution formed in the removing device, whereby appropriate temperature condition is set to each of the materials. (Yoshino, Y.)

Offshore gravimetric and subsidence monitoring

Energy Technology Data Exchange (ETDEWEB)

Stenvold, Torkjell

2008-06-15

The introduction (Chapter 1) is complemented by the introductions given in Chapters 2 to 8. I am the first author of the articles in chapter 2 and 8. For the 5 articles in between I am a coauthor, and the sum of my contributions to those articles (as quantified by the respective first authors) represents about one article. Chapter 2 contains the article 'High-precision relative depth and subsidence mapping from seafloor water-pressure measurements' by Stenvold et al. (2006), published in the SPE Journal. It was submitted in March 2005, and a revised version that also contained results from the Troll 2005 survey (August) was submitted in February 2006. The method of obtaining high-precision relative depth measurements by the use of mobile pressure gauges is presented. Intra-survey and inter-survey depth repeatabilities from six surveys are presented, and the individual contributing errors are discussed and estimated. Average reservoir compressibility for the Troll field between 2002 and 2005 is obtained by matching measured subsidence with modeled subsidence. Chapter 3 contains the article 'A new seafloor gravimeter' by Sasagawa et al. (2003), published in Geophysics. It was submitted in September 2001, and a revised version was submitted in August 2002. This article describes the ROVDOG (Remotely operated Vehicledeployed Deep-Ocean Gravimeter) in detail. Gravity and pressure repeatability results from the two first Troll surveys in 1998 and 2000 are presented. Data reduction, instrumental and environmental corrections are also presented. Chapter 4 contains the article 'Precision of seafloor gravity and pressure measurements for reservoir monitoring' by Zumberge et al., and was submitted 29 February 2008 to Geophysics. This builds on the article by Sasagawa et al. (Chapter 3). Improvements and upto date intra- and inter survey repeatability results are presented. The emphasis is on gravity results since the relative depth measurements

Use of sulfoxides for extraction-gravimetric determination of niobium and tantalum

International Nuclear Information System (INIS)

Nikolaev, A.I.; Babkin, A.G.; Tkachenko, V.G.

1977-01-01

An extraction-gravimetrical technique has been developed for determination of niobium and tantalum. The technique permits simultaneous extraction of tantalum and its concentrating in the aqueous phase; the range of Ta concentrations determined is essentially wider than in case of the routine gravimetric methods. The technique is based upon the fact, that tantalum is extracted by sulfoxides from fluorine-sulphate solutions at lower concentration of Hf and at lower ratios between the volumes of organic and aqueous phases than niobium. Two subsequent extractions by 1M sulfoxide solutions provide for practically complete transfer of tantalum into the organic phase, whereas extraction of niobium is only 3-20%. Sufficient recovery of Ta and Nb from organic phases is provided by re-extraction by NH 4 F solution. The technique is suitable for niobium and tantalum determination at the ratios of their pentoxides from 1:100 to 100:1. The disturbing influence of Fe(3) is suppressed by reductions to Fe(2)

Gravimetric determination of uranium(VI) and thorium(IV) with substituted pyrazolones

International Nuclear Information System (INIS)

Arora, H.C.; Rao, G.N.

1981-01-01

4-Acylpyrazolones like 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP), 1-phenyl-3-methyl-4-p-nitrobenzoyl-5-pyrazolone (PMNP) and 1-phenyl-3-methyl-4-(3,5 dinitrobenzoyl)-5-pyrazolone (PMDP) have been synthesized and developed as gravimetric reagents for the determination of U(VI) and Th(IV). Uranium(VI) is almost quantitatively precipitated with PMBP, PMNP, and PMDP at pH 2.20, 1.85 and 1.70 respectively. The pH values for the complete precipitation of thorium(IV) with PMBP, PMNP and PMDP are 2.90, 2.75 and 2.50 respectively. PMBP has proved to be an efficient ligand for gravimetric determination of U(VI) by direct weighing method after drying at 100 +- 10 deg C. The percentage relative error varies from 0.4 to 1.6 in the determination of U(VI) by this method. The effect of a number of interfering ions on the precipitation of U(VI) by PMBP has been reported. (author)

Magnetic states of single impurity in disordered environment

Directory of Open Access Journals (Sweden)

G.W. Ponedilok

2013-01-01

Full Text Available The charged and magnetic states of isolated impurities dissolved in amorphous metallic alloy are investigated. The Hamiltonian of the system under study is the generalization of Anderson impurity model. Namely, the processes of elastic and non-elastic scattering of conductive electrons on the ions of a metal and on a charged impurity are included. The configuration averaged one-particle Green's functions are obtained within Hartree-Fock approximation. A system of self-consistent equations is given for calculation of an electronic spectrum, the charged and the spin-polarized impurity states. Qualitative analysis of the effect of the metallic host structural disorder on the observed values is performed. Additional shift and broadening of virtual impurity level is caused by a structural disorder of impurity environment.

Mobile impurities in ferromagnetic liquids

Science.gov (United States)

Kantian, Adrian; Schollwoeck, Ulrich; Giamarchi, Thierry

2011-03-01

Recent work has shown that mobile impurities in one dimensional interacting systems may exhibit behaviour that differs strongly from that predicted by standard Tomonaga-Luttinger liquid theory, with the appearance of power-law divergences in the spectral function signifying sublinear diffusion of the impurity. Using time-dependent matrix product states, we investigate a range of cases of mobile impurities in systems beyond the analytically accessible examples to assess the existence of a new universality class of low-energy physics in one-dimensional systems. Correspondence: Adrian.Kantian@unige.ch This work was supported in part by the Swiss SNF under MaNEP and division II.

Impurity effects on ionic-liquid-based supercapacitors

International Nuclear Information System (INIS)

Liu, Kun; Lian, Cheng; Henderson, Douglas; Wu, Jianzhong

2016-01-01

Small amounts of an impurity may affect the key properties of an ionic liquid and such effects can be dramatically amplified when the electrolyte is under confinement. Here the classical density functional theory is employed to investigate the impurity effects on the microscopic structure and the performance of ionic-liquid-based electrical double-layer capacitors, also known as supercapacitors. Using a primitive model for ionic species, we study the effects of an impurity on the double layer structure and the integral capacitance of a room temperature ionic liquid in model electrode pores and find that an impurity strongly binding to the surface of a porous electrode can significantly alter the electric double layer structure and dampen the oscillatory dependence of the capacitance with the pore size of the electrode. Meanwhile, a strong affinity of the impurity with the ionic species affects the dependence of the integral capacitance on the pore size. Up to 30% increase in the integral capacitance can be achieved even at a very low impurity bulk concentration. As a result, by comparing with an ionic liquid mixture containing modified ionic species, we find that the cooperative effect of the bounded impurities is mainly responsible for the significant enhancement of the supercapacitor performance.

Impurity effects on ionic-liquid-based supercapacitors

Science.gov (United States)

Liu, Kun; Lian, Cheng; Henderson, Douglas; Wu, Jianzhong

2017-02-01

Small amounts of an impurity may affect the key properties of an ionic liquid and such effects can be dramatically amplified when the electrolyte is under confinement. Here the classical density functional theory is employed to investigate the impurity effects on the microscopic structure and the performance of ionic-liquid-based electrical double-layer capacitors, also known as supercapacitors. Using a primitive model for ionic species, we study the effects of an impurity on the double layer structure and the integral capacitance of a room temperature ionic liquid in model electrode pores and find that an impurity strongly binding to the surface of a porous electrode can significantly alter the electric double layer structure and dampen the oscillatory dependence of the capacitance with the pore size of the electrode. Meanwhile, a strong affinity of the impurity with the ionic species affects the dependence of the integral capacitance on the pore size. Up to 30% increase in the integral capacitance can be achieved even at a very low impurity bulk concentration. By comparing with an ionic liquid mixture containing modified ionic species, we find that the cooperative effect of the bounded impurities is mainly responsible for the significant enhancement of the supercapacitor performance.

EUV impurity study of the Alcator tokamak

International Nuclear Information System (INIS)

Terry, J.L.; Chen, K.I.; Moos, H.W.; Marmar, E.S.

1978-01-01

The intensity of resonance line radiation from oxygen, nitrogen, carbon and molybdenum impurities has been measured in the high-field (80kG), high-density (6x10 14 cm -3 ) discharges of the Alcator Tokamak, using a 0.4-m normal-incidence monochromator (300-1300A) with its line of sight fixed along a major radius. Total light-impurity concentrations of a few tenths of a percent have been estimated by using both a simple model and a computer code which included Pfirsch-Schlueter impurity diffusion. The resulting values of Zsub(eff), including the contributions due to both the light impurities and molybdenum, were close to one. The power lost through the impurity line radiation from the lower ionization states accounted for approximately 10% of the total Ohmic input power at high densities. (author)

Interactions of impurities with a moving grain boundary

Energy Technology Data Exchange (ETDEWEB)

Bauer, C L [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA)

1975-01-01

Most theories developed to explain interaction of impurities with a moving grain boundary involve a uniform excess impurity concentration distributed along a planar grain boundary. As boundary velocity increases, the excess impurities exert a net drag force on the boundary until a level is reached whereat the drag force no longer can balance the driving force and breakaway of the boundary from these impurities occurs. In this investigation, assumptions of a uniform lateral impurity profile and a planar grain boundary shape are relaxed by allowing both forward and lateral diffusion of impurities in the vicinity of a grain boundary. It is found that the two usual regions (drag of impurities by, and breakaway of a planar grain boundary) are separated by an extensive region wherein a uniform lateral impurity profile and a planar grain boundary shape are unstable. It is suspected that, in this unstable region, grain boundaries assume a spectrum of more complex morphologies and that elucidation of these morphologies can provide the first definitive description of the breakaway process and insight to more complex phenomena such as solid-solution strengthening, grain growth and secondary recrystallization.

Lattice dynamics of impurity clusters : application to pairs

International Nuclear Information System (INIS)

Chandralekha Devi, N.; Behera, S.N.

1979-01-01

A general solution is obtained for the lattice dynamics of a cluster of n-impurity atoms using the double-time Green's function formalism. The cluster is characterized by n-mass defect and m-force constant change parameters. It is shown that this general solution for the Green's function for the n-impurity cluster can also be expressed in terms of the Green's function for the (n-1)-impurity cluster. As an application, the cluster impurity modes for a pair are calculated using the Debye model for the host lattice dynamics. The splitting of the high frequency local modes and nearly zero frequency resonant modes due to pairs show an oscillatory behaviour on varying the distance of separation between the two impurity atoms. These oscillations are most prominent for two similar impurities and get damped for two dissimilar impurities or if one of the impurities produces a force constant change. The predictions of the calculation provide qualitative explanation of the data obtained from the infrared measurements of the resonant modes in mixed crystal system of KBrsub(1-c)Clsub(c):Lisup(+) and KBrsub(1-c)Isub(c):Lisup(+). (author)

Impurity transport in the Wendelstein VII-A stellarator

International Nuclear Information System (INIS)

1985-01-01

Impurity radiation losses in net-current-free neutral-beam-heated plasmas in the Wendelstein W VII-A stellarator are the combined effect of particularly strong impurity sources and improved particle confinement as compared with ohmically heated tokamak-like plasma discharges. Experiments are described and conclusions are drawn about the impurity species, their origin and their transport behaviour. The impurity transport is modelled by a 1-D impurity transport and radiation code. The evolution of the total radiation in time and space deduced from soft-X-ray and bolometer measurements can be fairly well simulated by the code. Experimentally, oxygen was found to make the main contribution to the radiation losses. In the calculations, an influx of cold oxygen desorbed from the walls of the order of 10 13 -10 14 cm -2 .s -1 and a rate of fast injected oxygen corresponding to a 1% impurity content of the neutral beams in combination with neoclassical impurity transport leads to quantitative agreement between the simulation and the observed radiation. The transport of A1 trace impurities injected by the laser blow-off technique was experimentally studied by soft-X-ray measurements using a differential method allowing extraction of the time evolution of A1 XII, XIII radial profiles. These are compared with code predictions, together with additional spectroscopic measurements. The main features of the impurity transport are consistent with neoclassical predictions, which explain particularly the central impurity accumulation. Some details, however, seem to require additional 'anomalous' transport. Such an enhancement is correlated with distortions of the magnetic configuration around resonant magnetic surfaces. (author)

Uranium analysis. Impurities determination by spark mass spectrometry

International Nuclear Information System (INIS)

Anon.

Determination of impurities in uranium, suitable for atomic content greater than 10 -8 , particularly adapted for a low content. The method is quantitative for metallic impurities and qualitative for non metallic impurities [fr

Fluid and gyrokinetic simulations of impurity transport at JET

DEFF Research Database (Denmark)

Nordman, H; Skyman, A; Strand, P

2011-01-01

Impurity transport coefficients due to ion-temperature-gradient (ITG) mode and trapped-electron mode turbulence are calculated using profile data from dedicated impurity injection experiments at JET. Results obtained with a multi-fluid model are compared with quasi-linear and nonlinear gyrokinetic...... simulation results obtained with the code GENE. The sign of the impurity convective velocity (pinch) and its various contributions are discussed. The dependence of the impurity transport coefficients and impurity peaking factor −∇nZ/nZ on plasma parameters such as impurity charge number Z, ion logarithmic...

Method for detecting trace impurities in gases

Science.gov (United States)

Freund, S.M.; Maier, W.B. II; Holland, R.F.; Beattie, W.H.

A technique for considerably improving the sensitivity and specificity of infrared spectrometry as applied to quantitative determination of trace impurities in various carrier or solvent gases is presented. A gas to be examined for impurities is liquefied and infrared absorption spectra of the liquid are obtained. Spectral simplification and number densities of impurities in the optical path are substantially higher than are obtainable in similar gas-phase analyses. Carbon dioxide impurity (approx. 2 ppM) present in commercial Xe and ppM levels of Freon 12 and vinyl chloride added to liquefied air are used to illustrate the method.

Process and system for removing impurities from a gas

Science.gov (United States)

Henningsen, Gunnar; Knowlton, Teddy Merrill; Findlay, John George; Schlather, Jerry Neal; Turk, Brian S

2014-04-15

A fluidized reactor system for removing impurities from a gas and an associated process are provided. The system includes a fluidized absorber for contacting a feed gas with a sorbent stream to reduce the impurity content of the feed gas; a fluidized solids regenerator for contacting an impurity loaded sorbent stream with a regeneration gas to reduce the impurity content of the sorbent stream; a first non-mechanical gas seal forming solids transfer device adapted to receive an impurity loaded sorbent stream from the absorber and transport the impurity loaded sorbent stream to the regenerator at a controllable flow rate in response to an aeration gas; and a second non-mechanical gas seal forming solids transfer device adapted to receive a sorbent stream of reduced impurity content from the regenerator and transfer the sorbent stream of reduced impurity content to the absorber without changing the flow rate of the sorbent stream.

Humidity and Gravimetric Equivalency Adjustments for Nephelometer-Based Particulate Matter Measurements of Emissions from Solid Biomass Fuel Use in Cookstoves

Science.gov (United States)

Soneja, Sutyajeet; Chen, Chen; Tielsch, James M.; Katz, Joanne; Zeger, Scott L.; Checkley, William; Curriero, Frank C.; Breysse, Patrick N.

2014-01-01

Great uncertainty exists around indoor biomass burning exposure-disease relationships due to lack of detailed exposure data in large health outcome studies. Passive nephelometers can be used to estimate high particulate matter (PM) concentrations during cooking in low resource environments. Since passive nephelometers do not have a collection filter they are not subject to sampler overload. Nephelometric concentration readings can be biased due to particle growth in high humid environments and differences in compositional and size dependent aerosol characteristics. This paper explores relative humidity (RH) and gravimetric equivalency adjustment approaches to be used for the pDR-1000 used to assess indoor PM concentrations for a cookstove intervention trial in Nepal. Three approaches to humidity adjustment performed equivalently (similar root mean squared error). For gravimetric conversion, the new linear regression equation with log-transformed variables performed better than the traditional linear equation. In addition, gravimetric conversion equations utilizing a spline or quadratic term were examined. We propose a humidity adjustment equation encompassing the entire RH range instead of adjusting for RH above an arbitrary 60% threshold. Furthermore, we propose new integrated RH and gravimetric conversion methods because they have one response variable (gravimetric PM2.5 concentration), do not contain an RH threshold, and is straightforward. PMID:24950062

Humidity and gravimetric equivalency adjustments for nephelometer-based particulate matter measurements of emissions from solid biomass fuel use in cookstoves.

Science.gov (United States)

Soneja, Sutyajeet; Chen, Chen; Tielsch, James M; Katz, Joanne; Zeger, Scott L; Checkley, William; Curriero, Frank C; Breysse, Patrick N

2014-06-19

Great uncertainty exists around indoor biomass burning exposure-disease relationships due to lack of detailed exposure data in large health outcome studies. Passive nephelometers can be used to estimate high particulate matter (PM) concentrations during cooking in low resource environments. Since passive nephelometers do not have a collection filter they are not subject to sampler overload. Nephelometric concentration readings can be biased due to particle growth in high humid environments and differences in compositional and size dependent aerosol characteristics. This paper explores relative humidity (RH) and gravimetric equivalency adjustment approaches to be used for the pDR-1000 used to assess indoor PM concentrations for a cookstove intervention trial in Nepal. Three approaches to humidity adjustment performed equivalently (similar root mean squared error). For gravimetric conversion, the new linear regression equation with log-transformed variables performed better than the traditional linear equation. In addition, gravimetric conversion equations utilizing a spline or quadratic term were examined. We propose a humidity adjustment equation encompassing the entire RH range instead of adjusting for RH above an arbitrary 60% threshold. Furthermore, we propose new integrated RH and gravimetric conversion methods because they have one response variable (gravimetric PM2.5 concentration), do not contain an RH threshold, and is straightforward.

Impurity control in TFTR

International Nuclear Information System (INIS)

Cecchi, J.L.

1980-06-01

The control of impurities in TFTR will be a particularly difficult problem due to the large energy and particle fluxes expected in the device. As part of the TFTR Flexibility Modification (TEM) project, a program has been implemented to address this problem. Transport code simulations are used to infer an impurity limit criterion as a function of the impurity atomic number. The configurational designs of the limiters and associated protective plates are discussed along with the consideration of thermal and mechanical loads due to normal plasma operation, neutral beams, and plasma disruptions. A summary is given of the materials-related research, which has been a collaborative effort involving groups at Argonne National Laboratory, Sandia Laboratories, and Princeton Plasma Physics Laboratory. Conceptual designs are shown for getterng systems capable of regenerating absorbed tritium. Research on this topic by groups at the previously mentioned laboratories and SAES Research Laboratory is reviewed

Local chemistry of Al and P impurities in silica

DEFF Research Database (Denmark)

Lægsgaard, Jesper; Stokbro, Kurt

2000-01-01

The local structure around Al and P impurities in silica is investigated using density-functional theory. Two distinct cases are considered: impurities substituting for a Si atom in alpha quartz, and impurities implanted in a stoichiometric alpha-quartz crystal. Both impurity elements are found t...

Impurity transport in internal transport barrier discharges on JET

International Nuclear Information System (INIS)

Dux, R.; Giroud, C.; Zastrow, K.-D.

2004-01-01

Impurity behaviour in JET internal transport barrier (ITB) discharges with reversed shear has been investigated. Metallic impurities accumulate in cases with too strong peaking of the main ion density profile. The accumulation is due to inwardly directed drift velocities inside the ITB radius. The strength of the impurity peaking increases with the impurity charge and is low for the low-Z elements C and Ne. Transport calculations show that the observed behaviour is consistent with dominant neoclassical impurity transport inside the ITB. In some cases, MHD events in the core flatten the radial profile of the metallic impurity. (author)

Crustal thickness of Antarctica estimated using data from gravimetric satellites

Directory of Open Access Journals (Sweden)

M. Llubes

2018-04-01

Full Text Available Computing a better crustal thickness model is still a necessary improvement in Antarctica. In this remote continent where almost all the bedrock is covered by the ice sheet, seismic investigations do not reach a sufficient spatial resolution for geological and geophysical purposes. Here, we present a global map of Antarctic crustal thickness computed from space gravity observations. The DIR5 gravity field model, built from GOCE and GRACE gravimetric data, is inverted with the Parker–Oldenburg iterative algorithm. The BEDMAP products are used to estimate the gravity effect of the ice and the rocky surface. Our result is compared to crustal thickness calculated from seismological studies and the CRUST1.0 and AN1 models. Although the CRUST1.0 model shows a very good agreement with ours, its spatial resolution is larger than the one we obtain with gravimetric data. Finally, we compute a model in which the crust–mantle density contrast is adjusted to fit the Moho depth from the CRUST1.0 model. In East Antarctica, the resulting density contrast clearly shows higher values than in West Antarctica.

Local order dependent impurity levels in alloy semiconductors

International Nuclear Information System (INIS)

Silva, C.E.T.G. da; Ecole Normale Superieure, 75 - Paris

1981-01-01

We develop a one band/may sites model for an isoelectronic impurity in a semiconductor alloy. The cluster-Bethe-lattice approximation is used to study the dependence of the impurity energy level upon the short range order (SRO) of the alloy. The Kikuchi parametrization is used to describe the latter. We take into account diagonal disorder only, with possible off-diagonal relaxation around the impurity site. All the inequivalent clusters of the impurity site and its first nearest neighbours are considered, thus including the important short range alloy potential fluctuations. Results are presented for the local density of impurity states, for different degrees of SRO in the alloy. (Author) [pt

Achieving improved ohmic confinement via impurity injection

International Nuclear Information System (INIS)

Bessenrodt-Weberpals, M.; Soeldner, F.X.

1991-01-01

Improved Ohmic Confinement (IOC) was obtained in ASDEX after a modification of the divertors that allowed a larger (deuterium and impurity) backflow from the divertor chamber. The quality of IOC depended crucially on the wall conditions, i.e. IOC was best for uncovered stainless steels walls and vanished with boronization. Furthermore, IOC was found only in deuterium discharges. These circumstances led to the idea that IOC correlates with the content of light impurities in the plasma. To substantiate this working hypothesis, we present observations in deuterium discharges with boronized wall conditions into which various impurities have been injected with the aim to induce IOC conditions. Firstly, the plasma behaviour in typical IOC discharges is characterized. Secondly, injection experiments with the low-Z impurities nitrogen and neon as well as with the high-Z impurities argon and krypton are discussed. Then, we concentrate on optimized neon puffing that yields the best confinement results which are similar to IOC conditions. Finally, these results are compared with eperiments in other tokamaks and some conclusions are drawn about the effects of the impurity puffing on both, the central and the edge plasma behaviour. (orig.)

Strategy for thermo-gravimetric analysis of K East fuel samples

International Nuclear Information System (INIS)

Lawrence, L.A.

1997-01-01

A strategy was developed for the Thermo-Gravimetric Analysis (TGA) testing of K East fuel samples for oxidation rate determinations. Tests will first establish if there are any differences for dry air oxidation between the K West and K East fuel. These tests will be followed by moist inert gas oxidation rate measurements. The final series of tests will consider pure water vapor i.e., steam

Influence of impurities on the crystallization of dextrose monohydrate

Science.gov (United States)

Markande, Abhay; Nezzal, Amale; Fitzpatrick, John; Aerts, Luc; Redl, Andreas

2012-08-01

The effects of impurities on dextrose monohydrate crystallization were investigated. Crystal nucleation and growth kinetics in the presence of impurities were studied using an in-line focused beam reflectance monitoring (FBRM) technique and an in-line process refractometer. Experimental data were obtained from runs carried out at different impurity levels between 4 and 11 wt% in the high dextrose equivalent (DE) syrup. It was found that impurities have no significant influence on the solubility of dextrose in water. However, impurities have a clear influence on the nucleation and growth kinetics of dextrose monohydrate crystallization. Nucleation and growth rate were favored by low levels of impurities in the syrup.

Striped morphologies induced by magnetic impurities in d-wave superconductors

International Nuclear Information System (INIS)

Zuo Xianjun

2011-01-01

Research Highlights: → We investigate striped morphologies induced by magnetic impurities in d-wave superconductors (DSCs). → For the single-impurity and two-impurity cases, modulated checkerboard pattern and stripe-like structures are induced. → When more magnetic impurities are inserted, more complex modulated structures could be induced, including rectilinear and right-angled stripes and quantum-corral-like structures. → Impurities could induce complex striped morphologies in DSCs. - Abstract: We study striped morphologies induced by magnetic impurities in d-wave superconductors (DSCs) near optimal doping by self-consistently solving the Bogoliubov-de Gennes equations based on the t - t' - U - V model. For the single-impurity case, it is found that the stable ground state is a modulated checkerboard pattern. For the two-impurity case, the stripe-like structures in order parameters are induced due to the impurity-pinning effect. The modulations of DSC and charge orders share the same period of four lattice constants (4a), which is half the period of modulations in the coexisting spin order. Interestingly, when three or more impurities are inserted, the impurities could induce more complex striped morphologies due to quantum interference. Further experiments of magnetic impurity substitution in DSCs are expected to check these results.

Comparison of neutron scattering, gravimetric and tensiometric methods for measuring soil water content in the field

International Nuclear Information System (INIS)

Jat, R.L.; Das, D.K.; Naskar, G.C.

1975-01-01

Water content of a sandy clay loam soil was measured by neutron scattering, gravimetric and tensiometric methods. Tensiometric measurement based on laboratory moisture retention curve gave comparatively higher moisture content than those obtained by other methods. No significant differences were observed among neutron meter, gravimetric and tensiometric measurement based on field calibration curve. Though for irrigation purposes all the methods can be used equally, use of tensiometric method with field calibration curve is suggested for easy and more accurate soil water content measurement where neutron meter is not available. (author)

Control and Prediction of the Course of Brewery Fermentations by Gravimetric Analysis

Czech Academy of Sciences Publication Activity Database

Košín, P.; Šavel, J.; Brož, A.; Sigler, Karel

2008-01-01

Roč. 53, č. 5 (2008), s. 451-456 ISSN 0015-5632 R&D Projects: GA MŠk 1M0570 Institutional research plan: CEZ:AV0Z50200510 Keywords : brewery fermentation * gravimetric analysis Subject RIV: EE - Microbiology, Virology Impact factor: 1.172, year: 2008

A gravimetric method for the determination of oxygen in uranium oxides and ternary uranium oxides by addition of alkaline earth compounds

International Nuclear Information System (INIS)

Fujino, Takeo; Tagawa, Hiroaki; Adachi, Takeo; Hashitani, Hiroshi

1978-01-01

A simple gravimetric determination of oxygen in uranium oxides and ternary uranium oxides is described. In alkaline earth uranates which are formed by heating in air at 800-1100 0 C, uranium is in the hexavalent state over certain continuous ranges of alkaline earth-to-uranium ratios. Thus, if an alkaline earth uranate or a compound containing an alkaline earth element, e.g. MgO, is mixed with the oxide sample and heated in air under suitable conditions, oxygen can be determined from the weight change before and after the reaction. The standard deviation of the O:U ratio for a UOsub(2+x) test sample is +-0.0008-0.001, if a correction is applied for atmospheric moisture absorbed during mixing. (Auth.)

Gravimetric Model of Quasigeoid in the Area of Slovakia

Directory of Open Access Journals (Sweden)

Juraj Papčo

2005-06-01

Full Text Available The gravimetric model of quasigeoid in the area of Slovakia was determined by using the revised and homogenised gravity mapping data in the scale of 1:25 000 from the area of Slovakia, and by using the mean Bouguer gravity anomalies with the resolution of 5´x7.5´ in the area 44°<φ<56° and 12°<λ<30° from abroad and by the digital terrain model DMR-2/ERTS89 with the resolution 3“ in the ellipsoidal latitude and 5“ in the ellipsoidal longitude from the area of Slovakia and the digital terrain model GTOPO30 with the resolution of 30“ in the ellipsoidal latitude and 30“ in the ellipsoidal longitude from abroad. The global part of the height anomaly was determined from the global geopotential model EGM96. The residual part of the height anomaly was determined by the Stokes integral formula. For the solution of the Stokes integra,l the Fast Fourier Transformation method in the spherical approximation was used. The gravimetric quasigeoid was tested by the GPS/levelling method using 46 points distributed on the area of Slovakia. The systematic trend of differences between height anomalies was rejected by the surface polynomial of second degree with 6 coefficients. The standard deviation after removing a systematic trend was 0.017 m

A Comparative Analysis of Seismological and Gravimetric Crustal Thicknesses below the Andean Region with Flat Subduction of the Nazca Plate

Directory of Open Access Journals (Sweden)

Mario E. Gimenez

2009-01-01

Full Text Available A gravimetric study was carried out in a region of the Central Andean Range between 28∘ and 32∘ south latitudes and from 72∘ and 66∘ west longitudes. The seismological and gravimetrical Moho models were compared in a sector which coincides with the seismological stations of the CHARGE project. The comparison reveals discrepancies between the gravity Moho depths and those obtained from seismological investigations (CHARGE project, the latter giving deeper values than those resulting from the gravimetric inversion. These discrepancies are attenuated when the positive gravimetric effect of the Nazca plate is considered. Nonetheless, a small residuum of about 5 km remains beneath the Cuyania terrane region, to the east of the main Andean chain. This residuum could be gravimetrically justified if the existence of a high density or eclogitized portion of the lower crust is considered. This result differed from the interpretations from Project “CHARGE” which revealed that the entire inferior crust extending from the Precordillera to the occidental “Sierras Pampeanas” could be “eclogitized”. In this same sector, we calculated the effective elastic thickness (Te of the crust. These results indicated an anomalous value of Te = 30 km below the Cuyania terrane. This is further conclusive evidence of the fact that the Cuyania terrane is allochthonous, for which also geological evidences exist.

Impurity screening of scrape-off plasma in a tokamak

International Nuclear Information System (INIS)

Kishimoto, Hiroshi; Tani, Keiji; Nakamura, Hiroo

1981-11-01

Impurity screening effect of a scrape-off layer has been studied in a tokamak, based on a simple model of wall-released impurity behavior. Wall-sputtered impurities are stopped effectively by the scrape-off plasma for a medium-Z or high-Z wall system while major part of impurities enters the main plasma in a low-Z wall system. The screening becomes inefficient with increase of scrape-off plasma temperature. Successive multiplication of recycling impurities in the scrape-off layer is large for a high-Z wall and is enhanced by a rise of scrape-off plasma temperature. The stability of plasma-wall interaction is determined by a multiplication factor of recycling impurities. (author)

Observation of impurity accumulation and concurrent impurity influx in PBX

International Nuclear Information System (INIS)

Sesnic, S.S.; Fonck, R.J.; Ida, K.; Couture, P.; Kaita, R.; Kaye, S.; Kugel, H.; LeBlanc, B.; Okabayashi, M.; Paul, S.; Powell, E.T.; Reusch, M.; Takahashi, H.; Gammel, G.; Morris, W.

1987-01-01

Impurity studies in L- and H-mode discharges in PBX have shown that both types of discharges can evolve into either an impurity accumulative or nonaccumulative case. In a typical accumulative discharge, Z eff peaks in the center to values of about 5. The central metallic densities can be high, n met /n e ≅ 0.01, resulting in central radiated power densities in excess of 1 W/cm 3 , consistent with bolometric estimates. The radial profiles of metals obtained independently from the line radiation in the soft X-ray and the VUV regions are very peaked. Concurrent with the peaking, an increase in the impurity influx coming from the edge of the plasma is observed. At the beginning of the accumulation phase the inward particle flux for titanium has values of 6x10 10 and 10x10 10 particles/cm 2 s at minor radii of 6 and 17 cm. At the end of the accumulation phase, this particle flux is strongly increased to values of 3x10 12 and 1x10 12 particles/cm 2 s. This increased flux is mainly due to influx from the edge of the plasma and to a lesser extent due to increased convective transport. Using the measured particle flux, an estimate of the diffusion coefficient D and the convective velocity v is obtained. (orig.)

Impurity induced resistivity upturns in underdoped cuprates

Energy Technology Data Exchange (ETDEWEB)

Das, Nabyendu, E-mail: nabyendudas@gmail.com; Singh, Navinder

2016-01-28

Impurity induced low temperature upturns in both the ab-plane and the c-axis dc-resistivities of cuprates in the pseudogap state have been observed in experiments. We provide an explanation of this phenomenon by incorporating impurity scattering of the charge carriers within a phenomenological model proposed by Yang, Rice and Zhang. The scattering between charge carriers and the impurity atom is considered within the lowest order Born approximation. Resistivity is calculated within Kubo formula using the impurity renormalized spectral functions. Using physical parameters for cuprates, we describe qualitative features of the upturn phenomena and its doping evolution that coincides with the experimental findings. We stress that this effect is largely due to the strong electronic correlations.

Impurity induced resistivity upturns in underdoped cuprates

International Nuclear Information System (INIS)

Das, Nabyendu; Singh, Navinder

2016-01-01

Impurity induced low temperature upturns in both the ab-plane and the c-axis dc-resistivities of cuprates in the pseudogap state have been observed in experiments. We provide an explanation of this phenomenon by incorporating impurity scattering of the charge carriers within a phenomenological model proposed by Yang, Rice and Zhang. The scattering between charge carriers and the impurity atom is considered within the lowest order Born approximation. Resistivity is calculated within Kubo formula using the impurity renormalized spectral functions. Using physical parameters for cuprates, we describe qualitative features of the upturn phenomena and its doping evolution that coincides with the experimental findings. We stress that this effect is largely due to the strong electronic correlations.

Low Z impurity transport in tokamaks. [Neoclassical transport theory

Energy Technology Data Exchange (ETDEWEB)

Hawryluk, R.J.; Suckewer, S.; Hirshman, S.P.

1978-10-01

Low Z impurity transport in tokamaks was simulated with a one-dimensional impurity transport model including both neoclassical and anomalous transport. The neoclassical fluxes are due to collisions between the background plasma and impurity ions as well as collisions between the various ionization states. The evaluation of the neoclassical fluxes takes into account the different collisionality regimes of the background plasma and the impurity ions. A limiter scrapeoff model is used to define the boundary conditions for the impurity ions in the plasma periphery. In order to account for the spectroscopic measurements of power radiated by the lower ionization states, fluxes due to anomalous transport are included. The sensitivity of the results to uncertainties in rate coefficients and plasma parameters in the periphery are investigated. The implications of the transport model for spectroscopic evaluation of impurity concentrations, impurity fluxes, and radiated power from line emission measurements are discussed.

Light impurity production in tokamaks

International Nuclear Information System (INIS)

Philipps, V.; Vietzke, E.; Erdweg, M.

1989-01-01

A review is given of the different erosion processes of carbon materials with special emphasis on conditions relevant to plasma surface interactions. New results on the chemical erosion and radiation enhanced sublimation of boron-carbon layers are presented. The chemical hydrocarbon formation produced by the interaction of the TEXTOR scrape-off plasma with a carbon target has been investigated up to temperatures of 1500K using a Sniffer probe. The chemical interaction of the plasma with the carbon walls in TEXTOR is also analysed by measuring the hydrocarbon and CO and CO 2 partial pressures built up on the surrounding walls during the discharges. The recycling of oxygen impurities in an all carbon surrounding occurs predominantly in the form of CO and Co 2 molecules and the analysis of both neutral pressures during the discharges has been used as an additional diagnostic for the oxygen impurity situation in TEXTOR. These data are discussed in view of spectroscopic measurements on the influx of carbon and oxygen atoms from the walls and impurity line radiation. CD-band spectroscopy in addition is employed to identify the hydrocarbon chemical carbon erosion. Our present understanding of the oxygen impurity recycling and the oxygen sources are described. Particle induced release of CO molecules from the entire first wall is believed to be the dominant influx process of oxygen in the SOL of plasmas with carbon facing materials. The influence of coating the TEXTOR first wall with a boron-carbon film (B/C ≅1) on the light impurity behaviour is shown. (author)

Novel gravimetric measurement technique for quantitative volume calibration in the sub-microliter range

International Nuclear Information System (INIS)

Liang, Dong; Zengerle, Roland; Steinert, Chris; Ernst, Andreas; Koltay, Peter; Bammesberger, Stefan; Tanguy, Laurent

2013-01-01

We present a novel measurement method based on the gravimetric principles adapted from the ASTM E542 and ISO 4787 standards for quantitative volume determination in the sub-microliter range. Such a method is particularly important for the calibration of non-contact micro dispensers as well as other microfluidic devices. The novel method is based on the linear regression analysis of continuously monitored gravimetric results and therefore is referred to as ‘gravimetric regression method (GRM)’. In this context, the regression analysis is necessary to compensate the mass loss due to evaporation that is significant for very small dispensing volumes. A full assessment of the measurement uncertainty of GRM is presented and results in a standard measurement uncertainty around 6 nl for dosage volumes in the range from 40 nl to 1 µl. The GRM has been experimentally benchmarked with a dual-dye ratiometric photometric method (Artel Inc., Westbrook, ME, USA), which can provide traceability of measurement to the International System of Units (SI) through reference standards maintained by NIST. Good precision (max. CV = 2.8%) and consistency (bias around 7 nl in the volume range from 40 to 400 nl) have been observed comparing the two methods. Based on the ASTM and ISO standards on the one hand and the benchmark with the photometric method on the other hand, two different approaches for establishing traceability for the GRM are discussed. (paper)

Comparison of gravimetric, creamatocrit and esterified fatty acid methods for determination of total fat content in human milk.

Science.gov (United States)

Du, Jian; Gay, Melvin C L; Lai, Ching Tat; Trengove, Robert D; Hartmann, Peter E; Geddes, Donna T

2017-02-15

The gravimetric method is considered the gold standard for measuring the fat content of human milk. However, it is labor intensive and requires large volumes of human milk. Other methods, such as creamatocrit and esterified fatty acid assay (EFA), have also been used widely in fat analysis. However, these methods have not been compared concurrently with the gravimetric method. Comparison of the three methods was conducted with human milk of varying fat content. Correlations between these methods were high (r(2)=0.99). Statistical differences (Pmethods. Overall, stronger correlation with lower mean (4.73g/L) and percentage differences (5.16%) was observed with the creamatocrit than the EFA method when compared to the gravimetric method. Furthermore, the ease of operation and real-time analysis make the creamatocrit method preferable. Copyright © 2016. Published by Elsevier Ltd.

Precision gravimetric survey at the conditions of urban agglomerations

Science.gov (United States)

Sokolova, Tatiana; Lygin, Ivan; Fadeev, Alexander

2014-05-01

Large cities growth and aging lead to the irreversible negative changes of underground. The study of these changes at the urban area mainly based on the shallow methods of Geophysics, which extensive usage restricted by technogenic noise. Among others, precision gravimetry is allocated as method with good resistance to the urban noises. The main the objects of urban gravimetric survey are the soil decompaction, leaded to the rocks strength violation and the karst formation. Their gravity effects are too small, therefore investigation requires the modern high-precision equipment and special methods of measurements. The Gravimetry division of Lomonosov Moscow State University examin of modern precision gravimeters Scintrex CG-5 Autograv since 2006. The main performance characteristics of over 20 precision gravimeters were examined in various operational modes. Stationary mode. Long-term gravimetric measurements were carried at a base station. It shows that records obtained differ by high-frequency and mid-frequency (period 5 - 12 hours) components. The high-frequency component, determined as a standard deviation of measurement, characterizes the level of the system sensitivity to external noise and varies for different devices from 2 to 5-7 μGals. Midrange component, which closely meet to the rest of nonlinearity gravimeter drifts, is partially compensated by the equipment. This factor is very important in the case of gravimetric monitoring or observations, when midrange anomalies are the target ones. For the examined gravimeters, amplitudes' deviations, associated with this parameter may reach 10 μGals. Various transportation modes - were performed by walking (softest mode), lift (vertical overload), vehicle (horizontal overloads), boat (vertical plus horizontal overloads) and helicopter. The survey quality was compared by the variance of the measurement results and internal convergence of series. The measurement results variance (from ±2 to ±4 μGals) and its

Control Strategy for Small Molecule Impurities in Antibody-Drug Conjugates.

Science.gov (United States)

Gong, Hai H; Ihle, Nathan; Jones, Michael T; Kelly, Kathleen; Kott, Laila; Raglione, Thomas; Whitlock, Scott; Zhang, Qunying; Zheng, Jie

2018-04-01

Antibody-drug conjugates (ADCs) are an emerging class of biopharmaceuticals. As such, there are no specific guidelines addressing impurity limits and qualification requirements. The current ICH guidelines on impurities, Q3A (Impurities in New Drug Substances), Q3B (Impurities in New Drug Products), and Q6B (Specifications: Test Procedures and Acceptance Criteria for Biotechnological/Biological Products) do not adequately address how to assess small molecule impurities in ADCs. The International Consortium for Innovation and Quality in Pharmaceutical Development (IQ) formed an impurities working group (IWG) to discuss this issue. This white paper presents a strategy for evaluating the impact of small molecule impurities in ADCs. This strategy suggests a science-based approach that can be applied to the design of control systems for ADC therapeutics. The key principles that form the basis for this strategy include the significant difference in molecular weights between small molecule impurities and the ADC, the conjugation potential of the small molecule impurities, and the typical dosing concentrations and dosing schedule. The result is that exposure to small impurities in ADCs is so low as to often pose little or no significant safety risk.

Impurity transport in internal transport barrier discharges on JET

International Nuclear Information System (INIS)

Dux, R.

2002-01-01

In JET plasmas with internal transport barrier (ITB) the behaviour of metallic and low-Z impurities (C, Ne) was investigated. In ITB discharges with reversed shear, the metallic impurities accumulate in cases with too strong peaking of the density profile, while the concentration of low-Z elements C and Ne is only mildly peaked. The accumulation might be so strong, that the central radiation approximately equals the central heating power followed by a radiative collapse of the transport barrier. The radial location with strong impurity gradients (convective barrier) was identified to be situated inside (not at!) the heat flux barrier. Calculations of neo-classical transport were performed for these discharges, including impurity-impurity collisions. It was found, that the observed Z-dependence of the impurity peaking and the location of the impurity 'barrier' can be explained with neo-classical transport. ITB discharges with monotonic shear show less inward convection and seem to be advantageous with respect to plasma purity. (author)

Microscopic models of impurities in silicon

International Nuclear Information System (INIS)

Assali, L.V.C.

1985-01-01

The study of electronic structure of insulated and complex puntual impurities in silicon responsible by the appearing of deep energy levels in the forbiden band of semiconductor, is presented. The molecular cluster model with the treatment of surface orbitals by Watson sphere within the formalism of Xα multiple scattering method, was used. The electronic structures of three clusters representative of perfect silicon crystal, which were used for the impurity studies, are presented. The method was applied to analyse insulated impurities of substitutional and interstitial hydrogen (Si:H and Si:H i ), subtitutional and interstitial iron in neutral and positive charge states (Si:Fe 0 , + , Si:Fe 0 , + ) and substitutional gold in three charge states(Si,Au - , 0 , + ). The thetraedic interstitial defect of silicon (Si:Si i ) was also studied. The complex impurities: neighbour iron pair in the lattice (Si:Fe 2 ), substitutional gold-interstitial iron pair (Si:Au s Fe) and substitutional boron-interstitial hydrogen pair (Si:B s H i ), were analysed. (M.C.K.) [pt

SPRED: a multichannel grazing-incidence spectrometer for plasma impurity diagnosis

International Nuclear Information System (INIS)

Fonck, R.J.; Ramsey, A.T.; Yelle, R.V.

1982-03-01

A compact vacuum ultraviolet spectrometer system has been developed to provide time-resolved impurity spectra from tokamak plasmas. Two interchangeable aberration-corrected toroidal diffraction gratings with flat focal fields provide simultaneous coverage over the ranges 100 to 1100 A or 160 to 1700 A. The detector is an intensified self-scanning photodiode array. Spectral resolution is 2 A with the higher dispersion grating. Minimum readout time for a full spectrum is 20 ms, but up to 7 individual spectral lines can be measured with a 1 ms time resolution. The sensitivity of the system is comparable to that of a conventional grazing incidence monochromator

SPRED: a multichannel grazing-incidence spectrometer for plasma impurity diagnosis

Energy Technology Data Exchange (ETDEWEB)

Fonck, R.J.; Ramsey, A.T.; Yelle, R.V.

1982-03-01

A compact vacuum ultraviolet spectrometer system has been developed to provide time-resolved impurity spectra from tokamak plasmas. Two interchangeable aberration-corrected toroidal diffraction gratings with flat focal fields provide simultaneous coverage over the ranges 100 to 1100 A or 160 to 1700 A. The detector is an intensified self-scanning photodiode array. Spectral resolution is 2 A with the higher dispersion grating. Minimum readout time for a full spectrum is 20 ms, but up to 7 individual spectral lines can be measured with a 1 ms time resolution. The sensitivity of the system is comparable to that of a conventional grazing incidence monochromator.

The electronic, magnetic and optical properties of ZnO doped with doubles impurities (Cr, Fe): An LDA-SIC and Monte Carlo study

Energy Technology Data Exchange (ETDEWEB)

Salmani, El Mehdi, E-mail: elmehdisalmani@gmail.com [LMPHE, Faculté des Sciences, Université Mohammed V, Rabat (Morocco); Laghrissi, Ayoub; Lamouri, Rachida; Ez-Zahraouy, Hamid [LMPHE, Faculté des Sciences, Université Mohammed V, Rabat (Morocco); Benyoussef, Abdelilah [Institute for Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Académie Hassan II des Sciences et Techniques, Rabat (Morocco)

2017-01-15

Electronic structure, magnetic and optical properties of ZnO doped with single and double impurities Zn{sub 1−x}Cr{sub x}O, Zn{sub 1−x}Fe{sub x}O, and Zn{sub 1−2x}Cr{sub x}Fe{sub x}O (x=0.03 and 0.06) are investigated using first-principles calculations. Based on the Korringa–Kohn–Rostoker method combined with the coherent potential approximation, we investigated the half-metallic ferromagnetic behavior of doubles impurities (Cr, Fe) doped ZnO. To support our results, we apply the self-interaction-corrected local density approximation (SIC-LDA) to study the electronic structure, optical and magnetic properties of Co-doped ZnO with doubles impurities (Cr, Fe) showing that the half-metallic ferromagnetic state still persists. The stability of the ferromagnetic state compared with the spin-glass state is investigated by comparing their total energies. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in ferromagnetic states with high Neel temperature. - Highlights: • The electronic structure calculations for ZnO doped with doubles impurities (Cr, Fe) have been discussed. • The half-metallic aspect was proven to take place for doubles impurities (Cr, Fe) codoped ZnO. • The doubles impurities (Cr, Fe)impurities are shown to introduce the necessary magnetic moment that makes ZnO good candidates for spintronic applications.

Observations of long impurity confinement times in the ISX tokamak

Energy Technology Data Exchange (ETDEWEB)

Burrell, K H; Wong, S K; Muller, III, C H; Hacker, M P [General Atomic Co., San Diego, CA (USA); Ketterer, H E; Isler, R C; Lazarus, E A [Oak Ridge National Lab., TN (USA)

1981-08-01

The transport of small amounts of silicon and aluminium injected into plasmas in the Impurity Study Experiment (ISX) tokamak is studied. By monitoring the time behaviour of ultra-violet spectral lines emitted by various charge states of those impurities and comparing this behaviour to the predictions of a multi-species impurity transport code, it is found that both impurity penetration times and impurity containment times are consistent with neoclassical predictions. The observed impurity containment times, which are greater than three times the energy containment time, are consistent with the inward convection predicted by neoclassical theory.

Numerical studies of impurities in fusion plasmas

International Nuclear Information System (INIS)

Hulse, R.A.

1982-09-01

The coupled partial differential equations used to describe the behavior of impurity ions in magnetically confined controlled fusion plasmas require numerical solution for cases of practical interest. Computer codes developed for impurity modeling at the Princeton Plasma Physics Laboratory are used as examples of the types of codes employed for this purpose. These codes solve for the impurity ionization state densities and associated radiation rates using atomic physics appropriate for these low-density, high-temperature plasmas. The simpler codes solve local equations in zero spatial dimensions while more complex cases require codes which explicitly include transport of the impurity ions simultaneously with the atomic processes of ionization and recombination. Typical applications are discussed and computational results are presented for selected cases of interest

Study of the corrosion behavior of magnesium alloy weddings in NaCl solutions by gravimetric tests

Energy Technology Data Exchange (ETDEWEB)

Segarra, J. A.; Calderon, B.; Portoles, A.

2015-07-01

In this article, the corrosion behavior of commercial AZ31 welded plates in aqueous chloride media was investigated by means of gravimetric techniques and Neutral Salt Spray tests (NSS). The AZ31 samples tested were welded using Gas Tugsten Arc Welding (GTAW) and different filler materials. Material microstructures were investigated by optical microscopy to stablish the influence of those microstructures in the corrosion behavior. Gravimetric and NSS tests indicate that the use of more noble filler alloys for the sample welding, preventing the reduction of aluminum content in weld beads, does not imply a better corrosion behavior. (Author)

A detailed gravimetric geoid of North America, the North Atlantic, Eurasia, and Australia

Science.gov (United States)

Marsh, J. G.

1973-01-01

A computer program was developed for the calculation of a goid based upon a combination of satellite and surface gravity data. A detailed gravimetric geoid of North America, the North Atlantic, Eurasia, and Australia was derived by using this program.

Impurity study of TMX using ultraviolet spectroscopy

International Nuclear Information System (INIS)

Allen, S.L.; Strand, O.T.; Moos, H.W.; Fortner, R.J.; Nash, T.J.; Dietrich, D.D.

1981-01-01

An extreme ultraviolet (EUV) study of the emissions from intrinsic and injected impurities in TMX is presented. Two survey spectrographs were used to determine that the major impurities present were oxygen, nitrogen, carbon, and titanium. Three absolutely-calibrated monochromators were used to measure the time histories and radial profiles of these impurity emissions in the central cell and each plug. Two of these instruments were capable of obtaining radial profiles as a function of time in a single shot

Multiscaling Dynamics of Impurity Transport in Drift-Wave Turbulence

International Nuclear Information System (INIS)

Futatani, S.; Benkadda, S.; Nakamura, Y.; Kondo, K.

2008-01-01

Intermittency effects and the associated multiscaling spectrum of exponents are investigated for impurities advection in tokamak edge plasmas. The two-dimensional Hasagawa-Wakatani model of resistive drift-wave turbulence is used as a paradigm to describe edge tokamak turbulence. Impurities are considered as a passive scalar advected by the plasma turbulent flow. The use of the extended self-similarity technique shows that the structure function relative scaling exponent of impurity density and vorticity follows the She-Leveque model. This confirms the intermittent character of the impurities advection in the turbulent plasma flow and suggests that impurities are advected by vorticity filaments

Toroidal asymmetries in divertor impurity influxes in NSTX

Directory of Open Access Journals (Sweden)

F. Scotti

2017-08-01

Full Text Available Toroidal asymmetries in divertor carbon and lithium influxes were observed in NSTX, due to toroidal differences in surface composition, tile leading edges, externally-applied three-dimensional (3D fields and toroidally-localized edge plasma modifications due to radio frequency heating. Understanding toroidal asymmetries in impurity influxes is critical for the evaluation of total impurity sources, often inferred from measurements with a limited toroidal coverage. The toroidally-asymmetric lithium deposition induced asymmetries in divertor lithium influxes. Enhanced impurity influxes at the leading edge of divertor tiles were the main cause of carbon toroidal asymmetries and were enhanced during edge localized modes. Externally-applied 3D fields led to strike point splitting and helical lobes observed in divertor impurity emission, but marginal changes to the toroidally-averaged impurity influxes. Power coupled to the scrape-off layer SOL plasma during radio frequency (RF heating of H-mode discharges enhanced impurity influxes along the non-axisymmetric divertor footprint of flux tubes connecting to plasma in front of the RF antenna.

Gravimetric method for in vitro calibration of skin hydration measurements.

Science.gov (United States)

Martinsen, Ørjan G; Grimnes, Sverre; Nilsen, Jon K; Tronstad, Christian; Jang, Wooyoung; Kim, Hongsig; Shin, Kunsoo; Naderi, Majid; Thielmann, Frank

2008-02-01

A novel method for in vitro calibration of skin hydration measurements is presented. The method combines gravimetric and electrical measurements and reveals an exponential dependency of measured electrical susceptance to absolute water content in the epidermal stratum corneum. The results also show that absorption of water into the stratum corneum exhibits three different phases with significant differences in absorption time constant. These phases probably correspond to bound, loosely bound, and bulk water.

Separation and gravimetric determination of rare earths with N-(3-nitrobenzoyl), N-(3-tolyl) hydroxylamine

International Nuclear Information System (INIS)

Agrawal, Y.K.; Kapoor, H.L.

1977-01-01

The N-(3-nitrobenzoyl), N-(3-tolyl) hydroxylamine is used as a reagent for the separation and gravimetric determination of Ce 3+ , La 3+ , Pr 3+ , Nd 3+ , Sm 3+ and Gd 3+ . The optimum conditions of precipitation of these rare earths indicate that, by control of pH and judicious use of masking agents, these ions can be separated from, and determined gravimetrically among several other ions. Further, the stochiometric nature of the N-(3-nitrobenzoyl), N-(3-tolyl) hydroxylamine acid is advantageous for the direct determination by weighting of (C 14 H 11 N 2 O 4 ) 3 M complex without ignition to obtain oxides. These complexes are characterized by infrared spectra

Impurities and conductivity in a D-wave superconductor

International Nuclear Information System (INIS)

Balatsky, A.V.

1994-01-01

Impurity scattering in the unitary limit produces low energy quasiparticles with anisotropic spectrum in a two-dimensional d-wave superconductor. The authors describe a new quasi-one-dimensional limit of the quasiparticle scattering, which might occur in a superconductor with short coherence length and with finite impurity potential range. The dc conductivity in a d-wave superconductor is predicted to be proportional to the normal state scattering rate and is impurity-dependent. They show that quasi-one-dimensional regime might occur in high-T c superconductors with Zn impurities at low temperatures T approx-lt 10 K

Impurity with two electrons in the spherical quantum dot with Unite confinement potential

International Nuclear Information System (INIS)

Baghdasaryan, D A; Ghaltaghchyan, H Ts; Kazaryan, E M; Sarkisyan, H A

2016-01-01

Two-electron states in a spherical QD with the hydrogenic impurity located in the center and with a finite height confinement potential barrier are investigated. The effective mass mismatch have been taken into account. The dependence of ground state energy and Coulomb electron-electron interaction energy correction on the QD size is studied. The problem of the state exchange time control in QD is discussed, taking into account the spins of the electrons in the Russell-Saunders approximation. The effect of quantum emission has been shown. (paper)

On impurity handling in high performance stellarator/heliotron plasmas

International Nuclear Information System (INIS)

Burhenn, R.; Feng, Y.; Ida, K.

2008-10-01

The Large Helical Device (LHD) and Wendelstein 7-X (W7-X, under construction) are experiments specially designed to demonstrate long pulse (quasi steady-state) operation, which is an intrinsic property of Stellarators and Heliotrons. Significant progress was made in establishment of high performance plasmas. A crucial point is the increasing impurity confinement towards high density as observed at several machines (TJ-II, W7-AS, LHD) which can lead to impurity accumulation and early pulse termination by radiation collapse at high density. In addition, theoretical predictions for non-axisymmetric configurations prognosticate the absence of impurity screening by ion temperature gradients in standard ion root plasmas. Nevertheless, scenarios were found where impurity accumulation was successfully avoided in LHD and/or W7-AS by the onset of drag forces in the high density and low temperature scrape-off-layer, the generation of magnetic islands at the plasma boundary and to a certain degree also by ELMs, flushing out impurities and reducing the net-impurity influx into the core. Additionally, a reduction of impurity core confinement was observed in the W7-AS High Density H-mode (HDH) regime and by application of sufficient ECRH heating power. The exploration of such purification mechanisms is a demanding task for successful steady-state operation. The impurity transport at the plasma edge/SOL was identified to play a major role for the global impurity behaviour in addition to the core confinement. (author)

Gravimetric determination of cadmium with o-phenanthroline and iodide

International Nuclear Information System (INIS)

Yoshida, Hitoshi; Mizuno, Kazunori; Taga, Mitsuhiko; Hikime, Seiichiro

1976-01-01

Cadmium forms insoluble mixed ligand complex with o-phenanthroline and iodide ions. By using the complex a new gravimetric method for the determination of cadmium was investigated. The recommended analytical procedure is as follows: Adjust pH value of a solution containing 5 to 45 mg cadmium to 4 with 3 M acetic acid-sodium acetate buffer solution. Add over threefold moles of potassium iodide to the solution and heat to just before boiling. To the solution add 0.1% ascorbic acid solution and then 0.1 M o-phenanthroline solution drop by drop in excess with stirring, and cool the mixture to room temperature. Filter the precipitates and wash first with 0.01% potassium iodide solution and then with water. Dry the precipitates at 110 0 C for two hours and weigh as Cd(o-phen) 2 I 2 (I). The gravimetric factor of the complex for cadmium is 0.1547. Chemical composition of the precipitate is variable when o-phenanthroline is added less than twofold moles to cadmium. Adding the o-phenanthroline solution 2.4-fold moles against cadmium, the ternary complex (I) precipitates quantitatively. Though a large excess of iodide ion in the solution contaminated the precipitate, the contamination was avoided when precipitation was carryed out at high temperature and in the presence of ascorbic acid. By the presented procedure 5 to 45 mg of cadmium are determined with a standard deviation of 0 C. (JPN)

Striped morphologies induced by magnetic impurities in d-wave superconductors

Science.gov (United States)

Zuo, Xian-Jun

2011-05-01

We study striped morphologies induced by magnetic impurities in d-wave superconductors (DSCs) near optimal doping by self-consistently solving the Bogoliubov-de Gennes equations based on the t - t‧ - U - V model. For the single-impurity case, it is found that the stable ground state is a modulated checkerboard pattern. For the two-impurity case, the stripe-like structures in order parameters are induced due to the impurity-pinning effect. The modulations of DSC and charge orders share the same period of four lattice constants (4 a), which is half the period of modulations in the coexisting spin order. Interestingly, when three or more impurities are inserted, the impurities could induce more complex striped morphologies due to quantum interference. Further experiments of magnetic impurity substitution in DSCs are expected to check these results.

Effects of impurity and Bose-Fermi interactions on the transition temperature of a dilute dipolar Bose-Einstein condensation in trapped Bose-Fermi mixtures

Science.gov (United States)

Yavari, H.; Mokhtari, M.

2014-03-01

The effects of impurity and Bose-Fermi interactions on the transition temperature of a dipolar Bose-Einstein condensation in trapped Bose-Fermi mixture, by using the two-fluid model, are investigated. The shift of the transition temperature consists of four contributions due to contact, Bose-Fermi, dipole-dipole, and impurity interactions. We will show that in the presence of an anisotropic trap, the Bose-Fermi correction to the shift of transition temperature due to the excitation spectra of the thermal part is independent of anisotropy factor. Applying our results to trapped Bose-Fermi mixtures shows that, by knowing the impurity effect, the shift of the transition temperature due to Bose-Fermi interaction could be measured for isotropic trap (dipole-dipole contributions is zero) and Feshbach resonance technique (contact potential contribution is negligible).

Higher-Order Fermi-Liquid Corrections for an Anderson Impurity Away from Half Filling

Science.gov (United States)

Oguri, Akira; Hewson, A. C.

2018-03-01

We study the higher-order Fermi-liquid relations of Kondo systems for arbitrary impurity-electron fillings, extending the many-body quantum theoretical approach of Yamada and Yosida. It includes, partly, a microscopic clarification of the related achievements based on Nozières' phenomenological description: Filippone, Moca, von Delft, and Mora [Phys. Rev. B 95, 165404 (2017), 10.1103/PhysRevB.95.165404]. In our formulation, the Fermi-liquid parameters such as the quasiparticle energy, damping, and transport coefficients are related to each other through the total vertex Γσ σ';σ'σ(ω ,ω';ω',ω ), which may be regarded as a generalized Landau quasiparticle interaction. We obtain exactly this function up to linear order with respect to the frequencies ω and ω' using the antisymmetry and analytic properties. The coefficients acquire additional contributions of three-body fluctuations away from half filling through the nonlinear susceptibilities. We also apply the formulation to nonequilibrium transport through a quantum dot, and clarify how the zero-bias peak evolves in a magnetic field.

Higher-Order Fermi-Liquid Corrections for an Anderson Impurity Away from Half Filling.

Science.gov (United States)

Oguri, Akira; Hewson, A C

2018-03-23

We study the higher-order Fermi-liquid relations of Kondo systems for arbitrary impurity-electron fillings, extending the many-body quantum theoretical approach of Yamada and Yosida. It includes, partly, a microscopic clarification of the related achievements based on Nozières' phenomenological description: Filippone, Moca, von Delft, and Mora [Phys. Rev. B 95, 165404 (2017)PRBMDO2469-995010.1103/PhysRevB.95.165404]. In our formulation, the Fermi-liquid parameters such as the quasiparticle energy, damping, and transport coefficients are related to each other through the total vertex Γ_{σσ^{'};σ^{'}σ}(ω,ω^{'};ω^{'},ω), which may be regarded as a generalized Landau quasiparticle interaction. We obtain exactly this function up to linear order with respect to the frequencies ω and ω^{'} using the antisymmetry and analytic properties. The coefficients acquire additional contributions of three-body fluctuations away from half filling through the nonlinear susceptibilities. We also apply the formulation to nonequilibrium transport through a quantum dot, and clarify how the zero-bias peak evolves in a magnetic field.

The Accuracy and Correction of Fuel Consumption from Controller Area Network Broadcast

Energy Technology Data Exchange (ETDEWEB)

Wang, Lijuan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gonder, Jeffrey D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wood, Eric W [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ragatz, Adam C [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-10-13

Fuel consumption (FC) has always been an important factor in vehicle cost. With the advent of electronically controlled engines, the controller area network (CAN) broadcasts information about engine and vehicle performance, including fuel use. However, the accuracy of the FC estimates is uncertain. In this study, the researchers first compared CAN-broadcasted FC against physically measured fuel use for three different types of trucks, which revealed the inaccuracies of CAN-broadcast fueling estimates. To match precise gravimetric fuel-scale measurements, polynomial models were developed to correct the CAN-broadcasted FC. Lastly, the robustness testing of the correction models was performed. The training cycles in this section included a variety of drive characteristics, such as high speed, acceleration, idling, and deceleration. The mean relative differences were reduced noticeably.

Monte Carlo method for magnetic impurities in metals

Science.gov (United States)

Hirsch, J. E.; Fye, R. M.

1986-01-01

The paper discusses a Monte Carlo algorithm to study properties of dilute magnetic alloys; the method can treat a small number of magnetic impurities interacting wiith the conduction electrons in a metal. Results for the susceptibility of a single Anderson impurity in the symmetric case show the expected universal behavior at low temperatures. Some results for two Anderson impurities are also discussed.

Computation of improved tidal parameters at the gravimetric station of Brasimone

Directory of Open Access Journals (Sweden)

P. Baldi

1997-06-01

Full Text Available Since 1991 a GWR superconducting gravimeter has been working in a laboratory at the Brasimone ENEA Research Centre, near Bologna (Italy, in the frame of an experimental program to verify Newton's law over distances of the order of 10-100 m. Owing to the aim of the experiment, the gravimeter was moved to different laboratories in the same area, but from August 1995 to date it has been working continuously in the same laboratory in the frame of the preliminary program of the Global Geodynamics Project. The site, belonging to a building of a dismissed nuclear power plant, is free from noise due to human activities, and is thus highly suitable for recording Earth tides. Starting from a set of gravimetric and atmospheric pressure data of high quality relative to 22 months of observation, we performed the tidal analysis using Eterna 3.2 software in order to compute amplitudes, gravimetric factors and phases of the main waves of the Tamura 1987 catalogue. The accuracy of the method adopted for the calibration of the gravimeter, the values of the principal waves and the result of the computation of atmospheric pressure admittance are described.

Mycotoxin metrology: Gravimetric production of zearalenone calibration solution

Science.gov (United States)

Rego, E. C. P.; Simon, M. E.; Li, Xiuqin; Li, Xiaomin; Daireaux, A.; Choteau, T.; Westwood, S.; Josephs, R. D.; Wielgosz, R. I.; Cunha, V. S.

2018-03-01

Food safety is a major concern for countries developing metrology and quality assurance systems, including the contamination of food and feed by mycotoxins. To improve the mycotoxin analysis and ensure the metrological traceability, CRM of calibration solution should be used. The production of certified mycotoxin solutions is a major challenge due to the limited amount of standard for conducting a proper purity study and due to the cost of standards. The CBKT project was started at BIPM and Inmetro produced gravimetrically one batch of zearelenone in acetronitrile (14.708 ± 0.016 μg/g, k=2) and conducted homogeneity, stability and value assignment studies.

Impurity dependence of superconductivity in niobium

International Nuclear Information System (INIS)

Laa, C.

1984-04-01

Jump temperatures, the critical fields Hsubc and Hsubc 2 and specific heats were measured on niobium samples where the impurity content was systematically varied by loading with nitrogen. Quantities could thus be extrapolated to lattice perfection and absolute purity. Comparisons with theories were made and some parameters extracted. Agreement was found with Gorkov theory for small impurities. A new value of the Ginsburg-Landau parameter Ko was determined to be just above 1/sqrt2 which proves that niobium is an elementary Type II semiconductor. By comparisons with the BCS and the CLAC theory the values of the mean Fermi velocity, the London penetration depth, the BCS coherence length and the impurity parameter were extracted. (G.Q.)

Impurity-induced states in superconducting heterostructures

Science.gov (United States)

Liu, Dong E.; Rossi, Enrico; Lutchyn, Roman M.

2018-04-01

Heterostructures allow the realization of electronic states that are difficult to obtain in isolated uniform systems. Exemplary is the case of quasi-one-dimensional heterostructures formed by a superconductor and a semiconductor with spin-orbit coupling in which Majorana zero-energy modes can be realized. We study the effect of a single impurity on the energy spectrum of superconducting heterostructures. We find that the coupling between the superconductor and the semiconductor can strongly affect the impurity-induced states and may induce additional subgap bound states that are not present in isolated uniform superconductors. For the case of quasi-one-dimensional superconductor/semiconductor heterostructures we obtain the conditions for which the low-energy impurity-induced bound states appear.

Interpretation of plasma impurity deposition probes. Analytic approximation

Science.gov (United States)

Stangeby, P. C.

1987-10-01

Insertion of a probe into the plasma induces a high speed flow of the hydrogenic plasma to the probe which, by friction, accelerates the impurity ions to velocities approaching the hydrogenic ion acoustic speed, i.e., higher than the impurity ion thermal speed. A simple analytic theory based on this effect provides a relation between impurity fluxes to the probe Γimp and the undisturbed impurity ion density nimp, with the hydrogenic temperature and density as input parameters. Probe size also influences the collection process and large probes are found to attract a higher flux density than small probes in the same plasma. The quantity actually measured, cimp, the impurity atom surface density (m-2) net-deposited on the probe, is related to Γimp and thus to nimp by taking into account the partial removal of deposited material caused by sputtering and the redeposition process.

Study of resolution enhancement methods for impurities quantitative analysis in uranium compounds by XRF

Energy Technology Data Exchange (ETDEWEB)

Silva, Clayton P.; Salvador, Vera L.R.; Cotrim, Marycel E.B.; Pires, Maria Ap. F.; Scapin, Marcos A., E-mail: clayton.pereira.silva@usp.b [Instituto de Pesquisas Energeticas e Nucleares (CQMA/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente

2011-07-01

X-ray fluorescence analysis is a technique widely used for the determination of both major and trace elements related to interaction between the sample and radiation, allowing direct and nondestructive analysis. However, in uranium matrices these devices are inefficient because the characteristic emission lines of elements like S, Cl, Zn, Zr, Mo and other overlap characteristic emission lines of uranium. Thus, chemical procedures to separation of uranium are needed to perform this sort of analysis. In this paper the deconvolution method was used to increase spectra resolution and correct the overlaps. The methodology was tested according to NBR ISO 17025 using a set of seven certified reference materials for impurities present in U3O8 (New Brunswick Laboratory - NBL). The results showed that this methodology allows quantitative determination of impurities such as Zn, Zr, Mo and others, in uranium compounds. The detection limits were shorter than 50{mu}g. g{sup -1} and uncertainty was shorter than 10% for the determined elements. (author)

Study of resolution enhancement methods for impurities quantitative analysis in uranium compounds by XRF

International Nuclear Information System (INIS)

Silva, Clayton P.; Salvador, Vera L.R.; Cotrim, Marycel E.B.; Pires, Maria Ap. F.; Scapin, Marcos A.

2011-01-01

X-ray fluorescence analysis is a technique widely used for the determination of both major and trace elements related to interaction between the sample and radiation, allowing direct and nondestructive analysis. However, in uranium matrices these devices are inefficient because the characteristic emission lines of elements like S, Cl, Zn, Zr, Mo and other overlap characteristic emission lines of uranium. Thus, chemical procedures to separation of uranium are needed to perform this sort of analysis. In this paper the deconvolution method was used to increase spectra resolution and correct the overlaps. The methodology was tested according to NBR ISO 17025 using a set of seven certified reference materials for impurities present in U3O8 (New Brunswick Laboratory - NBL). The results showed that this methodology allows quantitative determination of impurities such as Zn, Zr, Mo and others, in uranium compounds. The detection limits were shorter than 50μg. g -1 and uncertainty was shorter than 10% for the determined elements. (author)

The screening of charged impurities in bilayer graphene

International Nuclear Information System (INIS)

Zhang Wenjing; Li, Lain-Jong

2010-01-01

Positively charged impurities were introduced into a bilayer graphene (BLG) transistor by n-doping with dimethylformamide. Subsequent exposure of the BLG device to moisture resulted in a positive shift of the Dirac point and an increase of hole mobility, suggesting that moisture could reduce the scattering strength of the existing charged impurities. In other words, moisture screened off the 'effective density' of charged impurities. At the early stage of moisture screening the scattering of hole carriers is dominated by long-range Coulomb scatter, but an alternative scattering mechanism should also be taken into consideration when the effective density of impurities is further lowered on moisture exposure.

Collective impurity effects in the Heisenberg triangular antiferromagnet

International Nuclear Information System (INIS)

Maryasin, V S; Zhitomirsky, M E

2015-01-01

We theoretically investigate the Heisenberg antiferromagnet on a triangular lattice doped with nonmagnetic impurities. Two nontrivial effects resulting from collective impurity behavior are predicted. The first one is related to presence of uncompensated magnetic moments localized near vacancies as revealed by the low-temperature Curie tail in the magnetic susceptibility. These moments exhibit an anomalous growth with the impurity concentration, which we attribute to the clustering mechanism. In an external magnetic field, impurities lead to an even more peculiar phenomenon lifting the classical ground-state degeneracy in favor of the conical state. We analytically demonstrate that vacancies spontaneously generate a positive biquadratic exchange, which is responsible for the above degeneracy lifting

On neoclassical impurity transport in stellarator geometry

International Nuclear Information System (INIS)

García-Regaña, J M; Kleiber, R; Beidler, C D; Turkin, Y; Maaßberg, H; Helander, P

2013-01-01

The impurity dynamics in stellarators has become an issue of moderate concern due to the inherent tendency of the impurities to accumulate in the core when the neoclassical ambipolar radial electric field points radially inwards (ion root regime). This accumulation can lead to collapse of the plasma due to radiative losses, and thus limit high performance plasma discharges in non-axisymmetric devices. A quantitative description of the neoclassical impurity transport is complicated by the breakdown of the assumption of small E × B drift and trapping due to the electrostatic potential variation on a flux surface Φ-tilde compared with those due to the magnetic field gradient. This work examines the impact of this potential variation on neoclassical impurity transport in the Large Helical Device heliotron. It shows that the neoclassical impurity transport can be strongly affected by Φ-tilde . The central numerical tool used is the δf particle in cell Monte Carlo code EUTERPE. The Φ-tilde used in the calculations is provided by the neoclassical code GSRAKE. The possibility of obtaining a more general Φ-tilde self-consistently with EUTERPE is also addressed and a preliminary calculation is presented. (paper)

A highly accurate absolute gravimetric network for Albania, Kosovo and Montenegro

Science.gov (United States)

Ullrich, Christian; Ruess, Diethard; Butta, Hubert; Qirko, Kristaq; Pavicevic, Bozidar; Murat, Meha

2016-04-01

The objective of this project is to establish a basic gravity network in Albania, Kosovo and Montenegro to enable further investigations in geodetic and geophysical issues. Therefore the first time in history absolute gravity measurements were performed in these countries. The Norwegian mapping authority Kartverket is assisting the national mapping authorities in Kosovo (KCA) (Kosovo Cadastral Agency - Agjencia Kadastrale e Kosovës), Albania (ASIG) (Autoriteti Shtetëror i Informacionit Gjeohapësinor) and in Montenegro (REA) (Real Estate Administration of Montenegro - Uprava za nekretnine Crne Gore) in improving the geodetic frameworks. The gravity measurements are funded by Kartverket. The absolute gravimetric measurements were performed from BEV (Federal Office of Metrology and Surveying) with the absolute gravimeter FG5-242. As a national metrology institute (NMI) the Metrology Service of the BEV maintains the national standards for the realisation of the legal units of measurement and ensures their international equivalence and recognition. Laser and clock of the absolute gravimeter were calibrated before and after the measurements. The absolute gravimetric survey was carried out from September to October 2015. Finally all 8 scheduled stations were successfully measured: there are three stations located in Montenegro, two stations in Kosovo and three stations in Albania. The stations are distributed over the countries to establish a gravity network for each country. The vertical gradients were measured at all 8 stations with the relative gravimeter Scintrex CG5. The high class quality of some absolute gravity stations can be used for gravity monitoring activities in future. The measurement uncertainties of the absolute gravity measurements range around 2.5 micro Gal at all stations (1 microgal = 10-8 m/s2). In Montenegro the large gravity difference of 200 MilliGal between station Zabljak and Podgorica can be even used for calibration of relative gravimeters

Simulated impurity transport in LHD from MIST

Energy Technology Data Exchange (ETDEWEB)

Rice, J.E. [National Inst. for Fusion Science, Toki, Gifu (Japan)

1998-05-01

The impurity transport code MIST and atomic physics package LINES are used to calculate the time evolution of charge state density profiles, individual line emissivity profiles and total radiated power profiles for impurities in LHD plasmas. Three model LHD plasmas are considered; a high density, low temperature case, a low density, high temperature case and the initial LHD start-up plasma (500 kW ECH), using impurity transport coefficient profiles from Heliotron E. The elements oxygen, neon, scandium, iron, nickel and molybdenum are considered, both injected and in steady state. (author)

Evaluation of the gravimetric tetraphenylarsonium method for the determination of Tc(VII)

International Nuclear Information System (INIS)

Pacer, R.A.

1980-01-01

Solubility losses in the gravimetric tetraphenylarsonium method for determining pertechnetate have been evaluated. Liquid scintillation counting was used to measure the β - activity of 99 Tc in the filtrate, and indicated solubility losses of about 1% in analyses yielding 40 to 50 mg of precipitate. The solubility product of (C 6 H 5 ) 4 AsTcO 4 is estimated to be (8.6 +- 0.2) x 10 -10 at room temperature (24 to 25 0 ), and Ksub(sp) for (C 6 H 5 ) 4 AsReO 4 at approximately 21 to 23 0 is estimated at (2.6 +- 0.3) x 10 -9 . Both values are satisfactory for gravimetric purposes, but to keep solubility losses within 1% at least 40 mg of (C 6 H 5 ) 4 AsTcO 4 or 80 mg of (C 6 H 5 ) 4 AsReO 4 should be obtained (assuming 20 ml of solution, 20 to 30% excess of precipitant, and 6 or 7 washes with 5-ml portions of distilled water). (author)

Entanglement of heavy quark impurities and generalized gravitational entropy

Science.gov (United States)

Kumar, S. Prem; Silvani, Dorian

2018-01-01

We calculate the contribution from non-conformal heavy quark sources to the entanglement entropy (EE) of a spherical region in N=4 SUSY Yang-Mills theory. We apply the generalized gravitational entropy method to non-conformal probe D-brane embeddings in AdS5×S5, dual to pointlike impurities exhibiting flows between quarks in large-rank tensor representations and the fundamental representation. For the D5-brane embedding which describes the screening of fundamental quarks in the UV to the antisymmetric tensor representation in the IR, the EE excess decreases non-monotonically towards its IR asymptotic value, tracking the qualitative behaviour of the one-point function of static fields sourced by the impurity. We also examine two classes of D3-brane embeddings, one which connects a symmetric representation source in the UV to fundamental quarks in the IR, and a second category which yields the symmetric representation source on the Coulomb branch. The EE excess for the former increases from the UV to the IR, whilst decreasing and becoming negative for the latter. In all cases, the probe free energy on hyperbolic space with β = 2 π increases monotonically towards the IR, supporting its interpretation as a relative entropy. We identify universal corrections, depending logarithmically on the VEV, for the symmetric representation on the Coulomb branch.

Scattering of waves by impurities in precompressed granular chains.

Science.gov (United States)

Martínez, Alejandro J; Yasuda, Hiromi; Kim, Eunho; Kevrekidis, P G; Porter, Mason A; Yang, Jinkyu

2016-05-01

We study scattering of waves by impurities in strongly precompressed granular chains. We explore the linear scattering of plane waves and identify a closed-form expression for the reflection and transmission coefficients for the scattering of the waves from both a single impurity and a double impurity. For single-impurity chains, we show that, within the transmission band of the host granular chain, high-frequency waves are strongly attenuated (such that the transmission coefficient vanishes as the wavenumber k→±π), whereas low-frequency waves are well-transmitted through the impurity. For double-impurity chains, we identify a resonance-enabling full transmission at a particular frequency-in a manner that is analogous to the Ramsauer-Townsend (RT) resonance from quantum physics. We also demonstrate that one can tune the frequency of the RT resonance to any value in the pass band of the host chain. We corroborate our theoretical predictions both numerically and experimentally, and we directly observe almost complete transmission for frequencies close to the RT resonance frequency. Finally, we show how this RT resonance can lead to the existence of reflectionless modes in granular chains (including disordered ones) with multiple double impurities.

Spin-1 two-impurity Kondo problem on a lattice

Science.gov (United States)

Allerdt, A.; Žitko, R.; Feiguin, A. E.

2018-01-01

We present an extensive study of the two-impurity Kondo problem for spin-1 adatoms on a square lattice using an exact canonical transformation to map the problem onto an effective one-dimensional system that can be numerically solved using the density matrix renormalization group method. We provide a simple intuitive picture and identify the different regimes, depending on the distance between the two impurities, Kondo coupling JK, longitudinal anisotropy D , and transverse anisotropy E . In the isotropic case, two impurities on opposite (the same) sublattices have a singlet (triplet) ground state. However, the energy difference between the triplet ground state and the singlet excited state is very small and we expect an effectively fourfold-degenerate ground state, i.e., two decoupled impurities. For large enough JK the impurities are practically uncorrelated forming two independent underscreened states with the conduction electrons, a clear nonperturbative effect. When the impurities are entangled in an RKKY-like state, Kondo correlations persist and the two effects coexist: the impurities are underscreened, and the dangling spin-1 /2 degrees of freedom are responsible for the interimpurity entanglement. We analyze the effects of magnetic anisotropy in the development of quasiclassical correlations.

Breatherlike impurity modes in discrete nonlinear lattices

DEFF Research Database (Denmark)

Hennig, D.; Rasmussen, Kim; Tsironis, G. P.

1995-01-01

We investigate the properties of a disordered generalized discrete nonlinear Schrodinger equation, containing both diagonal and nondiagonal nonlinear terms. The equation models a Linear host lattice doped with nonlinear impurities. We find different types of impurity states that form itinerant...

Incorporation, diffusion and segregation of impurities in polycrystalline silicon

Energy Technology Data Exchange (ETDEWEB)

Deville, J.P.; Soltani, M.L. (Universite Louis Pasteur, 67 - Strasbourg (France)); Quesada, J. (Laboratoire de Metallurgie-Chimie des Materiaux, E.N.S.A.I.S., 67 - Strasbourg (France))

1982-01-01

We studied by means of X-Ray photoelectron Spectroscopy the nature, distribution and, when possible, the chemical bond of impurities at the surface of polycrystalline silicon samples grown on a carbon ribbon. Besides main impurities (carbon and oxygen), always present at concentrations around their limit of solubility in silicon, metal impurities have been found: their nature varies from one sample to another. Their spatial distribution is not random: some are strictly confined at the surface (sodium), whereas others are in the superficial oxidized layer (calcium, magnesium) or localized at the oxide-bulk silicon interface (iron). Metal impurities are coming from the carbon ribbon and are incorporated to silicon during the growth process. It is not yet possible to give a model of diffusion processes of impurities since they are too numerous and interact one with the other. However oxygen seems to play a leading role in the spatial distribution of metal impurities.

Quantum one dimensional spin systems. Disorder and impurities

International Nuclear Information System (INIS)

Brunel, V.

1999-01-01

This thesis presents three studies that are respectively the spin-1 disordered chain, the non magnetic impurities in the spin-1/2 chain and the reaction-diffusion process. The spin-1 chain of weak disorder is performed by the Abelian bosonization and the renormalization group. This allows to take into account the competition between the disorder and the interactions and predicts the effects of various spin-1 anisotropy chain phases under many different disorders. A second work uses the non magnetic impurities as local probes of the correlations in the spin-1/2 chain. When the impurities are connected to the chain boundary, the author predicts a temperature dependence of the relaxation rate (1/T) of the nuclear spin impurities, different from the case of these impurities connected to the whole chain. The last work deals with one dimensional reaction-diffusion problem. The Jordan-Wigner transformation allows to consider a fermionic field theory that critical exponents follow from the renormalization group. (A.L.B.)

Estimation of the internal structure of Trans-Mexican volcanic belt by gravimetric data

International Nuclear Information System (INIS)

Flores R, J.H.

1994-01-01

The regional gravimetric data of Trans-Mexican volcanic belt and surroundings, has been analyzed in order to estimate the depth of its internal structure. The short profiles with N-S orientation give a model of four shells with an average depth in the rank 24, 34, 56 and 83 kilometers. Only the profiles included between 97 West degrees to 102 West degrees give a depth of crust larger than the rest of the profiles with the same orientation. This profiles are associated with that of the Valleys of Toluca, D.F. and Puebla where the maximum crust thickness was estimated. The 3 long profiles with S-W orientation, give a model of 3 shells. The tendency of the first shell has a cortical thickness of 38 kilometers in the latitude of 18 North degrees. This tendency to increase the depth in the crust is associated with the minimum gravimetric in the map of Bouguer anomaly. (Author)

Impurity injection into tokamak plasmas by erosion probes

International Nuclear Information System (INIS)

Hildebrandt, D.; Bakos, J.S.; Buerger, G.; Paszti, F.; Petravich, G.

1987-08-01

Exposing special erosion probes into the edge plasma of MT-1 the impurities Li and Ti were released and contaminated the plasma. By the use of collector probes the torodial transport of these impurities were investigated. The results indicate a preferential impurity flow into codirection of the plasma current. However, the asymmetric component of this flow is much larger than expected from the toroidal drift correlated to the plasma current. (author)

Magnetometric and gravimetric surveys in fault detection over Acambay System

Science.gov (United States)

García-Serrano, A.; Sanchez-Gonzalez, J.; Cifuentes-Nava, G.

2013-05-01

In commemoration of the centennial of the Acambay intraplate earthquake of November 19th 1912, we carry out gravimetric and magnetometric surveys to define the structure of faults caused by this event. The study area is located approximately 11 km south of Acambay, in the Acambay-Tixmadeje fault system, where we performed two magnetometric surveys, the first consisting of 17 lines with a spacing of 35m between lines and 5m between stations, and the second with a total of 12 lines with the same spacing, both NW. In addition to these two lines we performed gravimetric profiles located in the central part of each magnetometric survey, with a spacing of 25m between stations, in order to correlate the results of both techniques, the lengths of such profiles were of 600m and 550m respectively. This work describes the data processing including directional derivatives, analytical signal and inversion, by means of which we obtain results of magnetic variations and anomaly traits highly correlated with those faults. It is of great importance to characterize these faults given the large population growth in the area and settlement houses on them, which involves a high risk in the security of the population, considering that these are active faults and cannot be discard earthquakes associated with them, so it is necessary for the authorities and people have relevant information to these problem.

Fractal growth in impurity-controlled solidification in lipid monolayers

DEFF Research Database (Denmark)

Fogedby, Hans C.; Sørensen, Erik Schwartz; Mouritsen, Ole G.

1987-01-01

A simple two-dimensional microscopic model is proposed to describe solidifcation processes in systems with impurities which are miscible only in the fluid phase. Computer simulation of the model shows that the resulting solids are fractal over a wide range of impurity concentrations and impurity...... diffusional constants. A fractal-forming mechanism is suggested for impurity-controlled solidification which is consistent with recent experimental observations of fractal growth of solid phospholipid domains in monolayers. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

Impurity effects in the electrothermal instability

International Nuclear Information System (INIS)

Tomimura, A.; Azevedo, M.T. de

1982-01-01

A 'impure' plasma model is proposed based on the homogeneous hydrogen plasma used in the theory formulated by Tomimura and Haines to explain the electrothermal instable mode growth with the wave vector perpendicular to the applied magnetic field. The impurities are introduced implicitly in the transport coefficients of the two-fluid model through a effective charge number Z sub(eff). (Author) [pt

Transport and re-deposition of limiter-released metal impurities

International Nuclear Information System (INIS)

Claasen, H.A.; Repp, H.

1983-01-01

The transport parallel B-vector and re-deposition of limiter- (or divertor-target-)released metal impurities in a given counter-streaming scrape-off layer plasma is studied analytically by using a kinetic approach. Electron impact ionization, Coulomb collisions with the hydrogen ions, and impurity ion acceleration in a pre-sheath electric field are accounted for. The friction and electric-field forces provide the driving forces for impurity re-cycling in front of the limiter. Both hydrogen ion sputtering and self-sputtering are included (the latter for impurity emission perpendicular to the limiter surface). The analytical formulas are numerically evaluated for the example of sputtered iron impurities, assuming a simple model for a scrape-off layer plasma in contact with a stainless-steel poloidal ring limiter. (author)

Transitions and excitations in a superfluid stream passing small impurities

KAUST Repository

Pinsker, Florian

2014-05-08

We analyze asymptotically and numerically the motion around a single impurity and a network of impurities inserted in a two-dimensional superfluid. The criticality for the breakdown of superfluidity is shown to occur when it becomes energetically favorable to create a doublet—the limiting case between a vortex pair and a rarefaction pulse on the surface of the impurity. Depending on the characteristics of the potential representing the impurity, different excitation scenarios are shown to exist for a single impurity as well as for a lattice of impurities. Depending on the lattice characteristics it is shown that several regimes are possible: dissipationless flow, excitations emitted by the lattice boundary, excitations created in the bulk, and the formation of large-scale structures.

Impurity concentration limits and activation in fusion reactor structural materials

International Nuclear Information System (INIS)

Zucchetti, M.

1991-01-01

This paper examines waste management problems related to impurity activation in first-wall, shield, and magnet materials for fusion reactors. Definitions of low activity based on hands-on recycling, remote recycling, and shallow land burial waste management criteria are discussed. Estimates of the impurity concentration in low-activation materials (elementally substituted stainless steels and vanadium alloys) are reported. Impurity activation in first-wall materials turns out to be critical after a comparison of impurity concentration limits and estimated levels. Activation of magnet materials is then considered: Long-term activity is not a concern, while short-term activity is. In both cases, impurity activation is negligible. Magnet materials, and all other less flux-exposed materials, have no practical limitation on impurities in terms of induced radioactivity

Transitions and excitations in a superfluid stream passing small impurities

KAUST Repository

Pinsker, Florian; Berloff, Natalia G.

2014-01-01

We analyze asymptotically and numerically the motion around a single impurity and a network of impurities inserted in a two-dimensional superfluid. The criticality for the breakdown of superfluidity is shown to occur when it becomes energetically favorable to create a doublet—the limiting case between a vortex pair and a rarefaction pulse on the surface of the impurity. Depending on the characteristics of the potential representing the impurity, different excitation scenarios are shown to exist for a single impurity as well as for a lattice of impurities. Depending on the lattice characteristics it is shown that several regimes are possible: dissipationless flow, excitations emitted by the lattice boundary, excitations created in the bulk, and the formation of large-scale structures.

The origin of metal impurities in DIVA

International Nuclear Information System (INIS)

Ohasa, Kazumi; Sengoku, Seio; Maeda, Hikosuke; Ohtsuka, Hideo; Yamamoto, Shin

1978-10-01

The origin of metal impurities in DIVA (JFT-2a Tokamak) has been studied experimentally. Three processes of metal impurity release from the first wall were identified; i.e. ion sputtering, evaporation, and arcing. Among of these, ion sputtering is the predominant process in the quiet phase of the discharge, which is characterized by no spikes in the loop voltage and no localized heat flux concentrations on the first wall. ''Cones'' formation due to the sputtering is observed on the gold protection plate (guard limiter) exposed to about 10,000 discharges by scanning electron micrograph. In the SEM photographs, the spacial distribution of cones on the shell surface due to the ion sputtering coincides with the spacial distribution of intensity of Au-I line radiation. Gold is the dominant metal impurity in DIVA. The honeycomb structure can decrease release of the metal impurity. (author)

Study by nuclear techniques of the impurity-defect interaction in implanted metals

International Nuclear Information System (INIS)

Thome, Lionel.

1978-01-01

The properties of out equilibrium alloys formed by impurity implantation are strongly influenced by radiation damage created during implantation. This work presents a study, via hyperfine interaction and lattice location experiments, of the impurity-defect interaction in ion implanted metals. When the impurity and defect concentrations in the implanted layer are small, i.e. when impurities are uniformly recoil implanted in the whole crystal volume following a nuclear reaction (Aq In experiments), the impurity interacts with its own damage cascade. In this case, a vacancy is found to be trapped by a fraction of impurities during an athermal process. The value of this fraction does not seem to depend critically on impurity and host. When the impurity and defect concentrations are such that defect cascades interact, i.e. when impurities are implanted with an isotope separator (Fe Yb experiments), the observed impurity-vacancy (or vacancy cluster) interactions depend then strongly on the nature of impurity and host. An empirical relation, which indicates the importance of elastic effects, has been found between the proportion of impurities interacting with defects and the difference between impurity and host atom radii. At implantation temperature such that vacancies are mobile, the impurity-defect interaction depends essentially on vacancy migration. A model based on chemical kinetics has been developed to account for the variation with temperature of measured quantities [fr

Application, advantages and limitations of high-density gravimetric surveys compared with three-dimensional geological modelling in dolomite stability investigations

OpenAIRE

Breytenbach, I J; Bosch, P J A

2011-01-01

The article discusses the nature of the gravimetric survey as applied and used in dolomite stability investigations on areas underlain by the Chuniespoort Group in South Africa. A short discussion is given on the gravimetric survey procedure along with its uses and alternative methods. Finally, two case studies illustrate the application of the method on a high-density survey grid spacing in comparison with three-dimensional geological modelling based on the lithology and karst weathering hor...

Impurity dynamics in stellarator W7-AS plasmas

International Nuclear Information System (INIS)

Igitkhanov, Yuri; Beidler, Craig D.; Burhenn, Reiner; Polunovsky, Eduard; Yamazaki, Kozo

2006-01-01

Numerical efforts to understand the neoclassical transport of impurities in stellarator plasmas have been undertaken. The new code solves the radial continuity equations for each ionization stage of the impurity ions for given background plasma profiles and magnetic configuration. An analytic description of the neoclassical transport coefficients based on numerical results from the DKES (Drift Kinetic Equation Solver) code and monoenergetic Monte-Carlo calculation (C.D. Beidler et al., EPS 1994), is here applied for impurity transport coefficients. The transition between the different charge states due to the ionization and recombination in balance equation is described by using the ADAS (Atomic Data and Analysis Structure) database. The impurity behavior in some typical discharges from W7-AS with moderate (NC) and improved energy confinement (HDH) has been considered. It is shown that the spatial distribution results from the competition between the radial electric field and the thermal force (which together produce a convective flux), and the diffusive term, which flattens the radial impurity distribution. The impurity ions are localized at the radial position where the convective flux goes through zero. It is also shown that for typical stellarator discharges there is no pronounced temperature screening effect as in tokamak plasmas. (author)

Impurity and trace tritium transport in tokamak edge turbulence

DEFF Research Database (Denmark)

Naulin, V.

2005-01-01

The turbulent transport of impurity or minority species, as for example tritium, is investigated in drift-Alfven edge turbulence. The full effects of perpendicular and parallel convection are kept for the impurity species. The impurity density develops a granular structure with steep gradients...... and locally exceeds its initial values due to the compressibility of the flow. An approximate decomposition of the impurity flux into a diffusive part and an effective convective part (characterized by a pinch velocity) is performed and a net inward pinch effect is recovered. The pinch velocity is explained...

Impurities in radioactive solutions for gamma spectroscopy

International Nuclear Information System (INIS)

Delgado, J.U.

1990-01-01

The absolute and relative methods for radioactive sources calibration, like 4 Πβ-γ and 4Πγ ionization chamber respectively, allows to reach 0,1% of exactiness in activity measurement, but cannot distinguish radioactive impurities that interfere in the activity. Then, one of the problems associated to a quality control of calibrated sources furnished to users is the identification and quantification of the impurities. In this work, a routine technical procedure, using the facilities of gamma spectrometry method that allows to identify and to determine the impurities relative contribution to the source main radionuclide activity, is described. (author) [pt

EUV impurity study of the Alcator tokamak

International Nuclear Information System (INIS)

Terry, J.L.; Chen, K.I.; Moos, H.W.; Marmar, E.S.

1977-06-01

The intensity of resonance line radiation from oxygen, nitrogen, carbon and molybdenum impurities has been measured in the high field (80 kG), high density (6 x 10 14 cm -3 ) discharges of the Alcator tokamak, using a 0.4 m normal incidence monochromator (300 to 1300 A) with its line of sight fixed along a major radius. The total light impurity concentrations were 2 x 10 -3 , 7 x 10 -4 , and 3 x 10 -3 at central electron densities of 4.5 x 10 13 cm -3 (burnout), 4.0 x 10 13 (low density plateau) and 6.0 x 10 14 (high density plateau). Both a simple model and a computer code which included Pfirsch-Schluter impurity diffusion were used to estimate oxygen influxes of 1.6 x 10 13 cm -2 sec -1 and 1.5 x 10 14 cm -2 sec -1 at the plasma edge in the low and high density emission plateaus. The resulting values of Z/sub eff/, including the contributions due to both the light impurities and molybdenum, were close to one. The power lost through the impurity line radiation accounted for approximately equal to 7 percent of the total ohmic input power at high densities

Transport of impurities during H-mode pulses in JET

International Nuclear Information System (INIS)

Giannella, R.; Gottardi, N.; Mompean, F.; Mori, H.; Pasini, D.; Stork, D.; Barnsley, R.; Hawkes, N.C.; Lawson, K.

1990-01-01

The transport of impurities during the H-mode is very different from that observed in the other regimes. This is clearly evident in the quiescent discharges where the confinement time of impurities τ I are measured in all the quiescent H-mode discharges in spite of the variety of impurity behavior observed corresponding to different plasma parameters and operating scenarios. The condition of the machine has an influence on the role played by the various impurities, but this does not seem to affect the flow patterns of these ions substantially. In particular oxygen, which was often detected as the dominant radiator, can be reduced to a negligible fraction by He conditioning of the carbon X-point tiles or limiters or by evaporating beryllium in the vacuum vessel. Nevertheless the behaviour of the residual impurities in otherwise similar discharges remains substantially unchanged. The transport patterns appear in fact to be affected by the plasma parameters and their profiles. In particular, two extreme transport regimes are presented in the following. These discharges have been modelled with the aid of a recently developed fully time-dependent impurity transport code using heuristic profiles for the impurity diffusion D and the convection velocity v. (author) 4 refs., 5 figs

Moving discrete breathers in a Klein-Gordon chain with an impurity

International Nuclear Information System (INIS)

Cuevas, J; Palmero, F; Archilla, J F R; Romero, F R

2002-01-01

We analyse the influence of an impurity in the evolution of moving discrete breathers in a Klein-Gordon chain with non-weak nonlinearity. Three different types of behaviour can be observed when moving breathers interact with the impurity: they pass through the impurity continuing their direction of movement; they are reflected by the impurity; they are trapped by the impurity, giving rise to chaotic breathers, as their Fourier power spectra show. Resonance with a breather centred at the impurity site is conjectured to be a necessary condition for the appearance of the trapping phenomenon. This paper establishes a difference between the resonance condition of the non-weak nonlinearity approach and the resonance condition with the linear impurity mode in the case of weak nonlinearity

The role of Co impurities and oxygen vacancies in the ferromagnetism of Co-doped SnO2: GGA and GGA+U studies

International Nuclear Information System (INIS)

Wang Hongxia; Yan Yu; Mohammed, Y. Sh.; Du Xiaobo; Li Kai; Jin Hanmin

2009-01-01

The electronic structure and ferromagnetic stability of Co-doped SnO 2 are studied using the first-principle density functional method within the generalized gradient approximation (GGA) and GGA+U schemes. The addition of effective U Co transforms the ground state of Co-doped SnO 2 to insulating from half-metallic and the coupling between the nearest neighbor Co spins to weak antimagnetic from strong ferromagnetic. GGA+U Co calculations show that the pure substitutional Co defects in SnO 2 cannot induce the ferromagnetism. Oxygen vacancies tend to locate near Co atoms. Their presence increases the magnetic moment of Co and induces the ferromagnetic coupling between two Co spins with large Co-Co distance. The calculated density of state and spin density distribution calculated by GGA+U Co show that the long-range ferromagnetic coupling between two Co spins is mediated by spin-split impurity band induced by oxygen vacancies. More charge transfer from impurity to Co-3d states and larger spin split of Co-3d and impurity states induced by the addition of U Co enhance the ferromagnetic stability of the system with oxygen vacancies. By applying a Coulomb U O on O 2 s orbital, the band gap is corrected for all calculations and the conclusions derived from GGA+U Co calculations are not changed by the correction of band gap.

Defect-impurity interactions in ion-implanted metals

International Nuclear Information System (INIS)

Turos, A.

1986-01-01

An overview of defect-impurity interactions in metals is presented. When point defects become mobile they migrate towards the sinks and on the way can be captured by impurity atoms forming stable associations so-called complexes. In some metallic systems complexes can also be formed athermally during ion implantation by trapping point defects already in the collision cascade. An association of a point defect with an impurity atom leads to its displacement from the lattice site. The structure and stability of complexes are strongly temperature dependent. With increasing temperature they dissociate or grow by multiple defect trapping. The appearance of freely migrating point defects at elevated temperatures, due to ion bombardment or thermal annealing, causes via coupling with defect fluxes, important impurity redistribution. Because of the sensitivity of many metal-in-metal implanted systems to radiation damage the understanding of this processes is essential for a proper interpretation of the lattice occupancy measurements and the optimization of implantation conditions. (author)

Glycolic acid physical properties and impurities assessment

Energy Technology Data Exchange (ETDEWEB)

Lambert, D. P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Pickenheim, B. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hay, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); BIBLER, N. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-08-09

This document has been revised to add analytical data for fresh, 1 year old, and 4 year old glycolic acid as recommended in Revision 2 of this document. This was needed to understand the concentration of formaldehyde and methoxyacetic acid, impurities present in the glycolic acid used in Savannah River National Laboratory (SRNL) experiments. Based on this information, the concentration of these impurities did not change during storage. These impurities were in the glycolic acid used in the testing included in this report and in subsequent testing using DuPont (now called Chemours) supplied Technical Grade 70 wt% glycolic acid. However, these impurities were not reported in the first two versions of this report. The Defense Waste Processing Facility (DWPF) is planning to implement a nitric-glycolic acid flowsheets to increase attainment to meet closure commitment dates during Sludge Batch 9. In fiscal year 2009, SRNL was requested to determine the physical properties of formic and glycolic acid blends.

Complexity of Quantum Impurity Problems

Science.gov (United States)

Bravyi, Sergey; Gosset, David

2017-12-01

We give a quasi-polynomial time classical algorithm for estimating the ground state energy and for computing low energy states of quantum impurity models. Such models describe a bath of free fermions coupled to a small interacting subsystem called an impurity. The full system consists of n fermionic modes and has a Hamiltonian {H=H_0+H_{imp}}, where H 0 is quadratic in creation-annihilation operators and H imp is an arbitrary Hamiltonian acting on a subset of O(1) modes. We show that the ground energy of H can be approximated with an additive error {2^{-b}} in time {n^3 \\exp{[O(b^3)]}}. Our algorithm also finds a low energy state that achieves this approximation. The low energy state is represented as a superposition of {\\exp{[O(b^3)]}} fermionic Gaussian states. To arrive at this result we prove several theorems concerning exact ground states of impurity models. In particular, we show that eigenvalues of the ground state covariance matrix decay exponentially with the exponent depending very mildly on the spectral gap of H 0. A key ingredient of our proof is Zolotarev's rational approximation to the {√{x}} function. We anticipate that our algorithms may be used in hybrid quantum-classical simulations of strongly correlated materials based on dynamical mean field theory. We implemented a simplified practical version of our algorithm and benchmarked it using the single impurity Anderson model.

Identification and accurate quantification of structurally related peptide impurities in synthetic human C-peptide by liquid chromatography-high resolution mass spectrometry.

Science.gov (United States)

Li, Ming; Josephs, Ralf D; Daireaux, Adeline; Choteau, Tiphaine; Westwood, Steven; Wielgosz, Robert I; Li, Hongmei

2018-06-04

Peptides are an increasingly important group of biomarkers and pharmaceuticals. The accurate purity characterization of peptide calibrators is critical for the development of reference measurement systems for laboratory medicine and quality control of pharmaceuticals. The peptides used for these purposes are increasingly produced through peptide synthesis. Various approaches (for example mass balance, amino acid analysis, qNMR, and nitrogen determination) can be applied to accurately value assign the purity of peptide calibrators. However, all purity assessment approaches require a correction for structurally related peptide impurities in order to avoid biases. Liquid chromatography coupled to high resolution mass spectrometry (LC-hrMS) has become the key technique for the identification and accurate quantification of structurally related peptide impurities in intact peptide calibrator materials. In this study, LC-hrMS-based methods were developed and validated in-house for the identification and quantification of structurally related peptide impurities in a synthetic human C-peptide (hCP) material, which served as a study material for an international comparison looking at the competencies of laboratories to perform peptide purity mass fraction assignments. More than 65 impurities were identified, confirmed, and accurately quantified by using LC-hrMS. The total mass fraction of all structurally related peptide impurities in the hCP study material was estimated to be 83.3 mg/g with an associated expanded uncertainty of 3.0 mg/g (k = 2). The calibration hierarchy concept used for the quantification of individual impurities is described in detail. Graphical abstract ᅟ.

Impurity and particle control for INTOR

International Nuclear Information System (INIS)

Post, D.

1985-02-01

The INTOR impurity control system studies have been focused on the development of an impurity control system which would be able to provide the necessary heat removal and He pumping while satisfying the requirements for (1) minimum plasma contamination by impurities, (2) reasonable component lifetime (approx. 1 year), and (3) minimum size and cost. The major systems examined were poloidal divertors and pumped limiters. The poloidal divertor was chosen as the reference option since it offered the possibility of low sputtering rates due to the formation of a cool, dense plasma near the collector plates. Estimates of the sputtering rates associated with pumped limiters indicated that they would be too high for a reasonable system. Development of an engineering design concept was done for both the poloidal divertor and the pumped limiter

Geopotential coefficient determination and the gravimetric boundary value problem: A new approach

Science.gov (United States)

Sjoeberg, Lars E.

1989-01-01

New integral formulas to determine geopotential coefficients from terrestrial gravity and satellite altimetry data are given. The formulas are based on the integration of data over the non-spherical surface of the Earth. The effect of the topography to low degrees and orders of coefficients is estimated numerically. Formulas for the solution of the gravimetric boundary value problem are derived.

EPR OF Mn2+ IMPURITIES IN CALCITE: A DETAILED STUDY PERTINENT TO MARBLE PROVENANCE DETERMINATION

DEFF Research Database (Denmark)

Weihe, H.; Piligkos, S.; Barra, A.L.

2009-01-01

We demonstrate that the electron paramagnetic resonance spectrum of Mn2+ impurities in calcite, and therefore also in marble, may be accurately reproduced by a traditional spin Hamiltonian formalism. The success of such a treatment, however, very much depends on the spin Hamiltonian parameters...... having the correct signs as well as magnitudes. We present data that determine the sign of the axial anisotropy parameter and thereby facilitate future quantum mechanical characterizations of marble electron paramagnetic resonance spectra that supplement provenance determination....

Scaling laws for trace impurity confinement: a variational approach

International Nuclear Information System (INIS)

Thyagaraja, A.; Haas, F.A.

1990-01-01

A variational approach is outlined for the deduction of impurity confinement scaling laws. Given the forms of the diffusive and convective components to the impurity particle flux, we present a variational principle for the impurity confinement time in terms of the diffusion time scale and the convection parameter, which is a non-dimensional measure of the size of the convective flux relative to the diffusive flux. These results are very general and apply irrespective of whether the transport fluxes are of theoretical or empirical origin. The impurity confinement time scales exponentially with the convection parameter in cases of practical interest. (orig.)

Zirconium analysis. Impurities determination by spark mass specrometry

International Nuclear Information System (INIS)

Anon.

Determination of impurities in zirconium, suitable for atomic content greater than 10 -8 but particularly adapted for low contents. The method is quantitative only if a reference sample is available (metallic impurities) [fr

Gravimetric and volumetric approaches adapted for hydrogen sorption measurements with in situ conditioning on small sorbent samples

International Nuclear Information System (INIS)

Poirier, E.; Chahine, R.; Tessier, A.; Bose, T.K.

2005-01-01

We present high sensitivity (0 to 1 bar, 295 K) gravimetric and volumetric hydrogen sorption measurement systems adapted for in situ sample conditioning at high temperature and high vacuum. These systems are designed especially for experiments on sorbents available in small masses (mg) and requiring thorough degassing prior to sorption measurements. Uncertainty analysis from instrumental specifications and hydrogen absorption measurements on palladium are presented. The gravimetric and volumetric systems yield cross-checkable results within about 0.05 wt % on samples weighing from (3 to 25) mg. Hydrogen storage capacities of single-walled carbon nanotubes measured at 1 bar and 295 K with both systems are presented

Isospin impurity and super-allowed β transitions

International Nuclear Information System (INIS)

Sagawa, H.; Van Giai Nguyen; Suzuki, T.

1999-01-01

We study the effect of isospin impurity on the super-allowed Fermi β decay using microscopic HF and RPA (or TDA) model taking into account CSB and CIB interactions. It is found that the isospin impurity of N = Z nuclei gives enhancement of the sum rule of Fermi transition probabilities. On the other hand, the super-allowed transitions between odd-odd J = 0 nuclei and even-even J = 0 nuclei are quenched because on the cancellation of the isospin impurity effects of mother and daughter nuclei. An implication of the calculated Fermi transition rate on the unitarity of Cabbibo-Kobayashi-Maskawa mixing matrix is also discussed. (authors)

Dynamics of impurities in the scrape-off layer

International Nuclear Information System (INIS)

Stangeby, P.C.; Commission of the European Communities, Abingdon

1988-01-01

Impurity modelling of the Scrape-Off Layer, SOL, is reviewed. Simple analytic models are sometimes adequate for relating central impurity levels to edge plasma conditions and for explaining the patterns of net erosion/deposition found on limiters. More sophisticated approaches, which are also necessary, are categorized and reviewed. A plea is made for the acquisition of a more comprehensive data base of edge plasma properties since reliable impurity modelling appears to be dependent on more extensive use of experimental input. (author)

The optimisation of limiter geometry to reduce impurity influx in tokamaks

International Nuclear Information System (INIS)

Matthews, G.F.; McCracken, G.M.; Sewell, P.; Goodall, D.H.J.; Stangeby, P.C.; Pitcher, C.S.

1987-01-01

Conventional limiters are designed to withstand large power loadings and hence are constructed with surfaces at grazing angles to the toroidal magnetic field. As a result any impurities released from the limiter surface are projected towards the centre of the plasma and are poorly screened from it. The impurity control limiter (ICL), an alternative concept which has an inverted geometry is discussed. The ICL shape is designed to direct the impurities towards the wall. Results are presented from a two-dimensional neutral particle code which maps the ionisation of carbon physically sputtered by deuterons from a carbon limiter. This ionisation source is coupled to a one-dimensional impurity transport code which calculates the implied central impurity density. The results demonstrate that the ICL achieves impurity control in two ways. Firstly, many of the sputtered impurities directed towards the wall are not ionised and return to the wall as neutrals. Secondly, much of the ionisation which does occur is located in the scrape-off layer. Here there is a strong ion sink which may also be enhanced by the flow of hydrogenic ions entraining impurity ions created close to the limiter surface. We conclude that a reduction in central impurity density of a factor of 10 is possible in a Tokamak such as DITE provided that the limiter is the main source of impurities. (author)

Anomalous temperature behavior of Sn impurities

International Nuclear Information System (INIS)

Haskel, D.; Shechter, H.; Stern, E.A.; Newville, M.; Yacoby, Y.

1993-01-01

Sn impurities in Pb and Ag hosts have been investigated by Moessbauer effect and in Pb by x-ray-absorption fine-structure (XAFS) studies. The Sn atoms are dissolved up to at least 2 at. % in Pb and up to at least 8 at. % in Ag for the temperature ranges investigated. The concentration limit for Sn-Sn interactions is 1 at. % for Pb and 2 at. % for Ag as determined experimentally by lowering the Sn concentration until no appreciable change occurs in the Moessbauer effect. XAFS measurements verify that the Sn impurities in Pb are dissolved and predominantly at substitutional sites. For both hosts the temperature dependence of the spectral intensities of isolated Sn impurities below a temperature T 0 is as expected for vibrating about a lattice site. Above T 0 the Moessbauer spectral intensity exhibits a greatly increased rate of drop-off with temperature without appreciable broadening. This drop-off is too steep to be explained by ordinary anharmonic effects and can be explained by a liquidlike rapid hopping of the Sn, localized about a lattice site. Higher-entropy-density regions of radii somewhat more than an atomic spacing surround such impurities, and can act as nucleation sites for three-dimensional melting

Interaction of ring dark solitons with ring impurities in Bose-Einstein condensates

International Nuclear Information System (INIS)

Xue Jukui

2005-01-01

The interaction of ring dark solitons/vortexes with the ring-shaped repulsive and attractive impurities in two-dimensional Bose-Einstein condensates is investigated numerically. Very rich interaction phenomena are obtained, i.e., not only the interaction between the ring soliton and the impurity, but also the interaction between vortexes and the impurity. The interaction characters, i.e., snaking of ring soliton, quasitrapping or reflection of ring soliton and vortexes by the impurity, strongly depend on initial ring soliton velocity, impurity strength, initial position of ring soliton and impurity. The numerical results also reveal that ring dark solitons/vortexes can be trapped and dragged by an adiabatically moving attractive ring impurity

Strong quantum scarring by local impurities

Science.gov (United States)

Luukko, Perttu J. J.; Drury, Byron; Klales, Anna; Kaplan, Lev; Heller, Eric J.; Räsänen, Esa

2016-11-01

We discover and characterise strong quantum scars, or quantum eigenstates resembling classical periodic orbits, in two-dimensional quantum wells perturbed by local impurities. These scars are not explained by ordinary scar theory, which would require the existence of short, moderately unstable periodic orbits in the perturbed system. Instead, they are supported by classical resonances in the unperturbed system and the resulting quantum near-degeneracy. Even in the case of a large number of randomly scattered impurities, the scars prefer distinct orientations that extremise the overlap with the impurities. We demonstrate that these preferred orientations can be used for highly efficient transport of quantum wave packets across the perturbed potential landscape. Assisted by the scars, wave-packet recurrences are significantly stronger than in the unperturbed system. Together with the controllability of the preferred orientations, this property may be very useful for quantum transport applications.

Impurities that cause difficulty in stripping actinides from commercial tetraalkylcarbamoylmethylphosphonates

International Nuclear Information System (INIS)

Bahner, C.T.; Shoun, R.R.; McDowell, W.J.

1977-09-01

Dihexyl[(diethylcarbamoyl)methyl]phosphonate (DHDECMP) in diethylbenzene extracts actinides well from 6 M nitric acid solution, but commercially available DHDECMP contains impurities which interfere with stripping the actinides from the organic extract. DHDECMP purified by molecular distillation does not contain these impurities, but the pot residue contains increased concentrations of them. Heating the purified DHDECMP causes the formation of products which interfere with stripping in the same way, suggesting that high temperatures employed in the manufacture of DHDECMP may produce the offending impurities. These impurities can be separated from the heat-decomposed material or the pot residues by dilution with a large volume of hexanes (causing part of the impurities to separate as a second liquid phase) followed by equilibration of the hexane solution with dilute alkali. After the treatment with hexane and dilute alkali, the DHDECMP is readily recovered and functions well in the actinide extraction process. Dibutyl[(dibutylcarbamoyl)methyl]-phosphonate (DBDBCMP) and di(2-ethylhexyl)[(diethylcarbamoyl)-methyl]phosphonate (DEHDECMP) are purified less effectively by these methods. Similar separation methods using diethylbenzene or CCl 4 as solvent do not remove impurities as completely as the hexane process. Impurities can also be removed from a benzene solution of the DHDECMP pot residue by passing it through a column packed with silica gel or diethylaminoethyl cellulose. These impurities have been separated into fractions for analytical examination by use of various solvents and by column chromatography. Hexyl hydrogen [(diethylcarbamoyl)methyl]-phosphonate has been identified tentatively as a principal objectionable impurity. Dihexyl phosphoric acid and possibly dihexylphosphonate have been identified in other fractions

Effects of impurities on radiation damage in InP

International Nuclear Information System (INIS)

Yamaguchi, M.; Ando, K.

1986-01-01

Strong impurity effects upon introduction and annealing behavior of radiation-induced defects in InP irradiated with 1-MeV electrons have been found. The main defect center of 0.37-eV hole trap H4 in p-InP, which must be due to a point defect, is annealed even at room temperature. Its annealing rate is found to be proportional to the 2/3 power of the preirradiation carrier concentration in InP. Moreover, the density of the hole trap H5 (E/sub v/+0.52 eV) in p-InP, which must be due to a point defect--impurity complex, increases with increase in the InP carrier concentration. These results suggest that the radiation-induced defects in InP must recover through long-range diffusion mediated by impurity atoms. A model is proposed in which point defects diffuse to sinks through impurities so as to disappear or bind impurities so as to form point defect--impurity complexes. In addition to the long-range diffusion mechanism, the possibility of charge-state effects responsible for the thermal annealing of radiation-induced defects in InP is also discussed

Synthesis, Isolation and Characterization of Process-Related Impurities in Oseltamivir Phosphate

Directory of Open Access Journals (Sweden)

Yogesh Kumar Sharma

2012-01-01

Full Text Available Three known impurities in oseltamivir phosphate bulk drug at level 0.1% (ranging from 0.05-0.1% were detected by gradient reverse phase high performance liquid chromatography. These impurities were preliminarily identified by the mass number of the impurities. Different experiments were conducted and finally the known impurities were synthesized and characterized.

Determination of plutonium in pure plutonium nitrate solutions - Gravimetric method

International Nuclear Information System (INIS)

1987-01-01

This International Standard specifies a precise and accurate gravimetric method for determining the concentration of plutonium in pure plutonium nitrate solutions and reference solutions, containing between 100 and 300 g of plutonium per litre, in a nitric acid medium. The weighed portion of the plutonium nitrate is treated with sulfuric acid and evaporated to dryness. The plutonium sulfate is decomposed and formed to oxide by heating in air. The oxide is ignited in air at 1200 to 1250 deg. C and weighed as stoichiometric plutonium dioxide, which is stable and non-hygroscopic

Spectroscopic studies of carbon impurities in PISCES-A

International Nuclear Information System (INIS)

Ra, Y.; Hirooka, Y.; Leung, W.K.; Conn, R.W.; Pospieszczyk, A.

1989-08-01

The graphite used for the limiter of the tokamak reactor produces carbon-containing molecular impurities as a result of the interactions with the edge plasma. The behavior of these molecular impurities has been studied using emission spectroscopy. The present study includes: finding molecular bands and atomic lines in the visible spectral range which can be used for the study of the molecular impurities, studying the breakup processes of the molecular impurities on their way from the source into the plasma, developing a spectroscopic diagnostic method for the absolute measurement of the molecular impurity flux resulting from graphite erosion. For these studies, carbon-containing molecules such as CH 4 , C 2 H 2 , C 2 H 4 , and CO 2 were injected into the tokamak-boundary,like plasma generated by PISCES-A. The spectrograms of these gases were taken. Many useful bands and lines were determined from the spectrograms. The breakup processes of these gases were studied by observing the spatial profiles of the emission of the molecules and their radicals for different plasma conditions. For the absolute measurement of the eroded molecular impurity flux, the photon efficiency of the lines and bands were found by measuring the absolute number of the emitted photons and injected gas molecules. The chemical sputtering yield of graphite by hydrogen plasma was spectroscopically measured using the previously obtained photon efficiencies. It showed good agreement with results obtained by weight loss measurements. 16 refs., 7 figs., 1 tab

Behaviour of the electron density near an impurity with exchange and correlation

International Nuclear Information System (INIS)

Adawi, I.; Godwin, V.E.

1982-09-01

The behaviour of the electron density n(r) and potential energy V(r) near an impurity of charge Z is studied in the linear response theory of metals with exchange and correlation. The leading two terms in nsub(odd)(r) and the first three terms in Vsub(odd)(r) are the same as in the Lindhard theory, but corrections appear in the higher terms of the odd powers expansions of these functions. In all quantum linear response theories, the derivative n'(0)=-2Zn 0 /a 0 where n 0 is the free electron gas density and a 0 is the Bohr radius. (author)

Oscillations of quantum transport through double-AB rings with magnetic impurity

International Nuclear Information System (INIS)

Gao Yingfang; Liang, J-Q

2006-01-01

We have studied the effect of impurity scattering on the quantum transport through double AB rings in the presence of spin-flipper in the middle lead in terms of one-dimensional quantum waveguide theory. The electron interacts with the impurity through the exchange interaction leading to spin-flip scattering. Transmissions in the spin-flipped and non-spin-flipped channels are calculated explicitly. It is found that the overall transmission and the conductance are distorted due to the impurity scattering. The extent of distortion not only depends on the strength of the impurity potential but also on the impurity position. Moreover, the transmission probability and the conductance are modulated by the magnetic flux, the size of the ring and the impurity potential strength as well

Investigation of impurity defects in α-iron by molecular dynamics method

International Nuclear Information System (INIS)

Kevorkyan, Yu.R.

1986-01-01

Investigation of the configuration of impurity defects in α-iron by the molecular dynamics method is presented. The Jhonson model potential has been used to calculate the interaction of matrix atoms. The impurity-matrix atom interaction is described by the same form of the potential shifted along the axis of interatomic distances for a definite value. The correspondence between the shift value and change in the radius of the impurity defect is established on the basis of calculation of the relaxation volume. Possible configurations of the impurity - interstitial matrix atom complexes are obtained for the given model of the impurity defect, dimensional boundaries of possible transitions between different configurations are determined. Formation and bound energies, relaxation volumes of impurity defects are calculated

Anomalous diffusion, clustering, and pinch of impurities in plasma edge turbulence

DEFF Research Database (Denmark)

Priego, M.; Garcia, O.E.; Naulin, V.

2005-01-01

The turbulent transport of impurity particles in plasma edge turbulence is investigated. The impurities are modeled as a passive fluid advected by the electric and polarization drifts, while the ambient plasma turbulence is modeled using the two-dimensional Hasegawa-Wakatani paradigm for resistive...... drift-wave turbulence. The features of the turbulent transport of impurities are investigated by numerical simulations using a novel code that applies semi-Lagrangian pseudospectral schemes. The diffusive character of the turbulent transport of ideal impurities is demonstrated by relative...... orientation determined by the charge of the impurity particles. Second, a radial pinch scaling linearly with the mass-charge ratio of the impurities is discovered. Theoretical explanation for these observations is obtained by analysis of the model equations. (C) 2005 American Institute of Physics....

Determination of 18 kinds of trace impurities in the vanadium battery grade vanadyl sulfate by ICP-OES

Science.gov (United States)

Yong, Cheng

2018-03-01

The method that direct determination of 18 kinds of trace impurities in the vanadium battery grade vanadyl sulfate by inductively coupled plasma atomic emission spectrometry (ICP-OES) was established, and the detection range includes 0.001% ∼ 0.100% of Fe, Cr, Ni, Cu, Mn, Mo, Pb, As, Co, P, Ti, Zn and 0.005% ∼ 0.100% of K, Na, Ca, Mg, Si, Al. That the influence of the matrix effects, spectral interferences and background continuum superposition in the high concentrations of vanadium ions and sulfate coexistence system had been studied, and then the following conclusions were obtained: the sulfate at this concentration had no effect on the determination, but the matrix effects or continuous background superposition which were generated by high concentration of vanadium ions had negative interference on the determination of potassium and sodium, and it produced a positive interference on the determination of the iron and other impurity elements, so that the impacts of high vanadium matrix were eliminated by the matrix matching and combining synchronous background correction measures. Through the spectral interference test, the paper classification summarized the spectral interferences of vanadium matrix and between the impurity elements, and the analytical lines, the background correction regions and working parameters of the spectrometer were all optimized. The technical performance index of the analysis method is that the background equivalent concentration -0.0003%(Na)~0.0004%(Cu), the detection limit of the element is 0.0001%∼ 0.0003%, RSD<10% when the element content is in the range from 0.001% to 0.007%, RSD< 20% even if the element content is in the range from 0.0001% to 0.001% that is beyond the scope of the method of detection, recoveries is 91.0% ∼ 110.0%.

Innovative sludge pretreatment technology for impurity separation using micromesh.

Science.gov (United States)

Mei, Xiaojie; Han, Xiaomeng; Zang, Lili; Wu, Zhichao

2018-05-23

In order to reduce the impacts on sludge treatment facilities caused by impurities such as fibers, hairs, plastic debris, and coarse sand, an innovative primary sludge pretreatment technology, sludge impurity separator (SIS), was proposed in this study. Non-woven micromesh with pore size of 0.40 mm was used to remove the impurities from primary sludge. Results of lab-scale tests showed that impurity concentration, aeration intensity, and channel gap were the key operation parameters, of which the optimized values were below 25 g/L, 0.8 m 3 /(m 2  min), and 2.5 cm, respectively. In the full-scale SIS with treatment capacity of 300 m 3 /day, over 88% of impurities could be removed from influent and the cleaning cycle of micromesh was more than 16 days. Economic analysis revealed that the average energy consumption was 1.06 kWh/m 3 treated sludge and operation cost was 0.6 yuan/m 3 treated sludge.

Carbon impurity transport around limiters in the DITE tokamak

International Nuclear Information System (INIS)

Pitcher, C.S.; Stangeby, P.C.; Goodall, D.H.J.; Matthews, G.F.; McCracken, G.M.

1989-01-01

The transport of impurity ions originating at the limiter in a tokamak is critically dependent on the location of the ion in the boundary plasma. In the confined plasma, just inboard of the limiter, impurity ions will disperse freely into the discharge whilst in the scrape-off layer the pre-sheath plasma flow and the associated ambipolar electric field may tend to sweep impurities back to the limiter surface. In this paper we have studied, both by experiment and by theory, the transport of carbon impurity ions in the vicinity of the limiter. By comparing experimental measurements of the spatial distributions of impurities around the limiter with that predicted from a Monte Carlo computer code it appears that the parallel dispersal on closed field lines in the confined plasma is consistent with classical transport processes and that in the scrape-off layer the dispersal is indeed impeded by the pre-sheath plasma flow. (orig.)

Interactions of Ultracold Impurity Particles with Bose-Einstein Condensates

Science.gov (United States)

2015-06-23

AFRL-OSR-VA-TR-2015-0141 INTERACTIONS OF ULTRACOLD IMPURITY PARTICLES WITH BOSE- EINSTEIN CONDENSATES Georg Raithel UNIVERSITY OF MICHIGAN Final...SUBTITLE Interactions of ultracold impurity particles with Bose- Einstein Condensates 5a. CONTRACT NUMBER FA9550-10-1-0453 5b. GRANT NUMBER 5c...Interactions of ultracold impurity particles with Bose- Einstein Condensates Contract/Grant #: FA9550-10-1-0453 Reporting Period: 8/15/2010 to 2/14

Study of the corrosion behavior of magnesium alloy weldings in NaCl solutions by gravimetric tests

Directory of Open Access Journals (Sweden)

Segarra, José A.

2015-09-01

Full Text Available In this article, the corrosion behavior of commercial AZ31 welded plates in aqueous chloride media was investigated by means of gravimetric techniques and Neutral Salt Spray tests (NSS. The AZ31 samples tested were welded using Gas Tugsten Arc Welding (GTAW and different filler materials. Material microstructures were investigated by optical microscopy to stablish the influence of those microstructures in the corrosion behavior. Gravimetric and NSS tests indicate that the use of more noble filler alloys for the sample welding, preventing the reduction of aluminum content in weld beads, does not imply a better corrosion behavior.En este artículo se ha investigado el comportamiento frente a la corrosión en medios acuosos salinos de chapas soldadas de aleación AZ31 mediante técnicas gravimétricas y ensayo en cámara de niebla salina. Las muestras estudiadas han sido soldadas mediante soldadura TIG (Tungsten Inert Gas y con diferentes materiales de aporte. En el estudio se ha empleado microscopía óptica para analizar la microestructura. Los ensayos de gravimetría y los ensayos de niebla salina indican que el empleo de materiales de aporte más nobles para soldar las muestras evitando la disminución del contenido en aluminio en los cordones, no implica un mejor comportamiento frente a la corrosión.

Impurity production and acceleration in CTIX

Energy Technology Data Exchange (ETDEWEB)

Buchenauer, D. [Sandia National Laboratories, MS-9161, P.O. Box 969, Livermore, CA 94550 (United States)], E-mail: dabuche@sandia.gov; Clift, W.M. [Sandia National Laboratories, MS-9161, P.O. Box 969, Livermore, CA 94550 (United States); Klauser, R.; Horton, R.D. [CTIX Group, University of California at Davis, Davis, CA 95616 (United States); Howard, S.J. [General Fusion Inc., Burnaby, BC V5A 3H4 (Canada); Brockington, S.J. [HyperV Technologies Corp., Chantilly, VA 20151 (United States); Evans, R.W.; Hwang, D.Q. [CTIX Group, University of California at Davis, Davis, CA 95616 (United States)

2009-06-15

The Compact Toroid Injection Experiment (CTIX) produces a high density, high velocity hydrogen plasma that maintains its configuration in free space on a MHD resistive time scale. In order to study the production and acceleration of impurities in the injector, several sets of silicon collector probes were exposed to spheromak-like CT's exiting the accelerator. Elemental analysis by Auger Electron Spectroscopy indicated the presence of O, Al, Fe, and Cu in films up to 200 A thickness (1000 CT interactions). Using a smaller number of CT interactions (10-20), implantation of Fe and Cu was measured by Auger depth profiling. The amount of impurities was found to increase with accelerating voltage and number of CT interactions while use of a solenoidal field reduced the amount. Comparison of the implanted Fe and Cu with TRIM simulations indicated that the impurities were traveling more slowly than the hydrogen CT.

Impurity-induced tuning of quantum-well States in spin-dependent resonant tunneling.

Science.gov (United States)

Kalitsov, Alan; Coho, A; Kioussis, Nicholas; Vedyayev, Anatoly; Chshiev, M; Granovsky, A

2004-07-23

We report exact model calculations of the spin-dependent tunneling in double magnetic tunnel junctions in the presence of impurities in the well. We show that the impurity can tune selectively the spin channels giving rise to a wide variety of interesting and novel transport phenomena. The tunneling magnetoresistance, the spin polarization, and the local current can be dramatically enhanced or suppressed by impurities. The underlying mechanism is the impurity-induced shift of the quantum well states (QWSs), which depends on the impurity potential, impurity position, and the symmetry of the QWS. Copyright 2004 The American Physical Society

Continuous-time quantum Monte Carlo impurity solvers

Science.gov (United States)

Gull, Emanuel; Werner, Philipp; Fuchs, Sebastian; Surer, Brigitte; Pruschke, Thomas; Troyer, Matthias

2011-04-01

Continuous-time quantum Monte Carlo impurity solvers are algorithms that sample the partition function of an impurity model using diagrammatic Monte Carlo techniques. The present paper describes codes that implement the interaction expansion algorithm originally developed by Rubtsov, Savkin, and Lichtenstein, as well as the hybridization expansion method developed by Werner, Millis, Troyer, et al. These impurity solvers are part of the ALPS-DMFT application package and are accompanied by an implementation of dynamical mean-field self-consistency equations for (single orbital single site) dynamical mean-field problems with arbitrary densities of states. Program summaryProgram title: dmft Catalogue identifier: AEIL_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEIL_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: ALPS LIBRARY LICENSE version 1.1 No. of lines in distributed program, including test data, etc.: 899 806 No. of bytes in distributed program, including test data, etc.: 32 153 916 Distribution format: tar.gz Programming language: C++ Operating system: The ALPS libraries have been tested on the following platforms and compilers: Linux with GNU Compiler Collection (g++ version 3.1 and higher), and Intel C++ Compiler (icc version 7.0 and higher) MacOS X with GNU Compiler (g++ Apple-version 3.1, 3.3 and 4.0) IBM AIX with Visual Age C++ (xlC version 6.0) and GNU (g++ version 3.1 and higher) compilers Compaq Tru64 UNIX with Compq C++ Compiler (cxx) SGI IRIX with MIPSpro C++ Compiler (CC) HP-UX with HP C++ Compiler (aCC) Windows with Cygwin or coLinux platforms and GNU Compiler Collection (g++ version 3.1 and higher) RAM: 10 MB-1 GB Classification: 7.3 External routines: ALPS [1], BLAS/LAPACK, HDF5 Nature of problem: (See [2].) Quantum impurity models describe an atom or molecule embedded in a host material with which it can exchange electrons. They are basic to nanoscience as

Impurity transport calculations for the limiter shadow region of a tokamak

International Nuclear Information System (INIS)

Claassen, H.A.; Repp, H.

1981-01-01

Impurity transport calculations are presented for the scrape-off layer of a tokamak with a poloidal ring limiter. The theory is based on the drift-kinetic equations for the impurity ions in their different ionization states. It is developed in the limit of low impurity concentrations under due consideration of electron impact ionization, Coulomb collisions with hydrogen ions streaming onto a neutralizing surface, a convection along the magnetic field, and a radial drift. The background plasma and the impurity sources at the walls enter the theory as input parameters. Numerical results are given for the radial profiles of density, temperature, particle flux, and energy flux of wall-released impurity ions as well as for the screening efficiency of the scrape-off layer neglecting impurity re-emission from the limiter. (author)

Modified method for zirconium or hafnium gravimetric determination with glycolic acid derivatives

International Nuclear Information System (INIS)

Barbieri, R.S.; Rocha, J.C.; Terra, V.R.; Marques Neto, A.

1989-01-01

The conditions for gravimetric determination of zirconium or hafnium by glicolic acid derivatives were studied by thermogravimetric analysis. The method utilized shown that after precipitation, washing and drying of precipitates at 150 0 C, the resulting solid was weighed in the form of [M{RCH(OH)COO} 4 ] (M = Zr,Hf;R = C 6 H 5 , β-C 10 H 7 ,p-BrC 6 H 4 ). (author) [pt

Comparison Of Metal Corrosion Inhibition By Gravimetric And Linear Polarization Resistance Methods

OpenAIRE

Banerji, Shankha

1992-01-01

Studies were conducted to evaluate the effectiveness of various dosages of the selected silicate and phosphate compounds applied for corrosion inhibition of cast iron, copper, lead, and galvanized steel specimens. The compounds selected for study were zinc polyphosphate (Calgon C-39), zinc orthophosphate (Virchem V-931), sodium metasilicate and glassy silicate. The effectiveness of these compounds for corrosion inhibition were studied under differing water quality conditions using gravimetric...

Radiation-chemical disinfection of dissolved impurities and environmental protection

International Nuclear Information System (INIS)

Petrukhin, N.V.; Putilov, A.V.

1986-01-01

Radiation-chemical neutralization of dissolved toxic impurities formed in the production processes of different materials, while modern plants being in use, is considered. For the first time the processes of deep industrial waste detoxication and due to this peculiarities of practically thorough neutralization of dissolved toxic impurities are considered. Attention is paid to devices and economic factors of neutralization of dissolved toxic impurities. The role of radiation-chemical detoxication for environment protection is considered

Effect of impurity radiation on tokamak equilibrium

International Nuclear Information System (INIS)

Rebut, P.H.; Green, B.J.

1977-01-01

The energy loss from a tokamak plasma due to the radiation from impurities is of great importance in the overall energy balance. Taking the temperature dependence of this loss for two impurities characteristic of those present in existing tokamak plasmas, the condition for radial power balance is derived. For the impurities considered (oxygen and iron) it is found that the radiation losses are concentrated in a thin outer layer of the plasma and the equilibrium condition places an upper limit on the plasma paraticle number density in this region. This limiting density scales with mean current density in the same manner as is experimentally observed for the peak number density of tokamak plasmas. The stability of such equilibria is also discussed. (author)

[Impurity removal technology of Tongan injection in liquid preparation process].

Science.gov (United States)

Yang, Xu-fang; Wang, Xiu-hai; Bai, Wei-rong; Kang, Xiao-dong; Liu, Jun-chao; Wu, Yun; Xiao, Wei

2015-08-01

In order to effectively remove the invalid impurities in Tongan injection, optimize the optimal parameters of the impurity removal technology of liquid mixing process, in this paper, taking Tongan injection as the research object, with the contents of celandine alkali, and sinomenine, solids reduction efficiency, and related substances inspection as the evaluation indexes, the removal of impurities and related substances by the combined process of refrigeration, coction and activated carbon adsorption were investigated, the feasibility of the impurity removal method was definited and the process parameters were optimized. The optimized process parameters were as follows: refrigerated for 36 h, boiled for 15 min, activated carbon dosage of 0.3%, temperature 100 degrees C, adsorption time 10 min. It can effectively remove the tannin, and other impurities, thus ensure the quality and safety of products.

Effects of helium impurities on superalloys

International Nuclear Information System (INIS)

Selle, J.E.

1977-07-01

A review of the literature on the effects of helium impurities on superalloys at elevated temperatures was undertaken. The actual effects of these impurities vary depending on the alloy, composition of the gas atmosphere, and temperature. In general, exposure in helium produces significant but not catastrophic changes in the structure and properties of the alloys. The effects of these treatments on the structure, creep, fatigue, and mechanical properties of the various alloys are reviewed and discussed. Suggestions for future work are presented

Identification and control of unspecified impurity in trimetazidine dihydrochloride tablet formulation

Science.gov (United States)

Jefri; Puspitasari, A. D.; Talpaneni, J. S. R.; Tjandrawinata, R. R.

2018-04-01

Trimetazidine dihydrochloride is an anti-ischemic metabolic agent which is used as drug for angina pectoris treatment. The drug substance monograph is available in European Pharmacopoeia and British Pharmacopoeia, while the drug product monograph is not available in any of the pharmacopoeias. During development of trimetazidine dihydrochloride tablet formulation, we found increase of an unspecified impurity during preliminary stability study. The unspecified impurity was identified by high performance liquid chromatography coupled with mass spectrometry (LC-MS) and the molecular weight obtained was matching with the molecular weight of N-formyl trimetazidine (m/z 295). Further experiments were performed to confirm the suspected result by injecting the impurity standard and spiking formic acid into the drug substance. The retention time of N-formyl trimetazidine was similar to the unspecified impurity in drug product. Even spiking of formic acid into drug substance showed that the suspected impurity increased with increasing concentration of formic acid. The proposed mechanism of impurity formation is via amidation of piperazine moiety of trimetazidine by formic acid which present as residual solvent in tablet binder used in the formulation. Subsequently, the impurity in our product was controlled by choosing the primary packaging which could minimize the formation of impurity.

Investigation of the impurity transport in the ASDEX tokamak by spectroscopical methods

International Nuclear Information System (INIS)

Krieger, K.W.

1990-12-01

Plasma impurities: a central problem of controlled thermonuclear fusion; magnetic plasma confinement in a Tokamak; methods to the determination of plasma impurity transport coefficients - by temporally modulated gas admission; the transport equation for impurities; neoclassical and anomalous transport; harmonic analysis of time-dependent signals; solutions of the transport equation; experimental equipment and measurements; measuring results - consistency of simple transport models with radial phase measurements; linearity of the transport processes; plasma disturbance by impurity injection; determination of the diffusion coefficient by simplified transport models; comparison of transport models for impurities and background plasma; measurements of the impurity transport at the plasma edge by high modulation frequencies. (AH)

Impurity effects of hydrogen isotope retention on boronized wall in LHD

International Nuclear Information System (INIS)

Oya, Yasuhisa; Okuno, Kenji; Ashikawa, Naoko; Nishimura, Kiyohiko; Sagara, Akio

2010-11-01

The impurity effect on hydrogen isotopes retention in the boron film deposited in LHD was evaluated by means of XPS and TDS. It was found that the impurity concentrations in boron film were increased after H-H main plasma exposure in LHD. The ratio of hydrogen retention trapped by impurity to total hydrogen retention during H-H main plasma exposure was reached to 70%, although that of deuterium retention by impurity in D 2 + implanted LHD-boron film was about 35%. In addition, the dynamic chemical sputtering of hydrogen isotopes with impurity as the form of water and / or hydrocarbons was occurred by energetic hydrogen isotopes irradiation. It was expected that the enhancement of impurity concentration during plasma exposure in LHD would induce the dynamic formation of volatile molecules and their re-emission to plasma. These facts would prevent stable plasma operation in LHD, concluding that the dynamic impurity behavior in boron film during plasma exposure is one of key issues for the steady-state plasma operation in LHD. (author)

Effect of suprathermal electrons on the impurity ionization state

International Nuclear Information System (INIS)

Ochando, M A; Medina, F; Zurro, B; McCarthy, K J; Pedrosa, M A; Baciero, A; Rapisarda, D; Carmona, J M; Jimenez, D

2006-01-01

The effect of electron cyclotron resonance heating induced suprathermal electron tails on the ionization of iron impurities in magnetically confined plasmas is investigated. The behaviour of plasma emissivity immediately after injection provides evidence of a spatially localized 'shift' towards higher charge states of the impurity. Bearing in mind that the non-inductive plasma heating methods generate long lasting non-Maxwellian distribution functions, possible implications on the deduced impurity transport coefficients, when fast electrons are present, are discussed

Multi-objective optimization for an automated and simultaneous phase and baseline correction of NMR spectral data

Science.gov (United States)

Sawall, Mathias; von Harbou, Erik; Moog, Annekathrin; Behrens, Richard; Schröder, Henning; Simoneau, Joël; Steimers, Ellen; Neymeyr, Klaus

2018-04-01

Spectral data preprocessing is an integral and sometimes inevitable part of chemometric analyses. For Nuclear Magnetic Resonance (NMR) spectra a possible first preprocessing step is a phase correction which is applied to the Fourier transformed free induction decay (FID) signal. This preprocessing step can be followed by a separate baseline correction step. Especially if series of high-resolution spectra are considered, then automated and computationally fast preprocessing routines are desirable. A new method is suggested that applies the phase and the baseline corrections simultaneously in an automated form without manual input, which distinguishes this work from other approaches. The underlying multi-objective optimization or Pareto optimization provides improved results compared to consecutively applied correction steps. The optimization process uses an objective function which applies strong penalty constraints and weaker regularization conditions. The new method includes an approach for the detection of zero baseline regions. The baseline correction uses a modified Whittaker smoother. The functionality of the new method is demonstrated for experimental NMR spectra. The results are verified against gravimetric data. The method is compared to alternative preprocessing tools. Additionally, the simultaneous correction method is compared to a consecutive application of the two correction steps.

Photometrically measured continuous personal PM(2.5) exposure: levels and correlation to a gravimetric method.

Science.gov (United States)

Lanki, Timo; Alm, Sari; Ruuskanen, Juhani; Janssen, Nicole A H; Jantunen, Matti; Pekkanen, Juha

2002-05-01

There is evidence that hourly variations in exposure to airborne particulate matter (PM) may be associated with adverse health effects. Still there are only few published data on short-term levels of personal exposure to PM in community settings. The objectives of the study were to assess hourly and shorter-term variations in personal PM(2.5) exposure in Helsinki, Finland, and to compare results from portable photometers to simultaneously measured gravimetric concentrations. The effect of relative humidity on the photometric results was also evaluated. Personal PM(2.5) exposures of elderly persons were assessed for 24 h every second week, resulting in 308 successful measurements from 47 different subjects. Large changes in concentrations in minutes after cooking or changing microenvironment were seen. The median of daily 1-h maxima was over twice the median of 24-h averages. There was a strong significant association between the two means, which was not linear. Median (95th percentile) of the photometric 24-h concentrations was 12.1 (37.7) and of the 24-h gravimetric concentrations 9.2 (21.3) microg/m3. The correlation between the photometric and the gravimetric method was quite good (R2=0.86). Participants spent 94.1% of their time indoors or in a vehicle, where relative humidity is usually low and thus not likely to cause significant effects on photometric results. Even outdoors, the relative humidity had only modest effect on concentrations. Photometers are a promising method to explore the health effects of short-term variation in personal PM(2.5) exposure.

Damping of elastic waves in crystals with impurities

International Nuclear Information System (INIS)

Lemanov, V.V.; Petrov, A.V.; Akhmedzhanov, F.R.; Nasyrov, A.N.

1979-01-01

Elastic wave damping and thermal conductivity of NaCl-NaBr and Y 3 AL 5 O 12 crystals with Er impurity has been examined. The experimental results on a decrease in elastic wave damping in such crystals are analyzed in the framework of the Ahiezer damping theory. The measurements were made in the frequency range of 300-1500 MHz in propagation of longitudinal and transverse elastic waves along the [100] and [110] directions. At 10 % concentration of erbium impurity the transverse wave damping decreases by a factor of three, and for longitudinal waves by a factor of two in NaBr:Cl crystals, and by approximately 10 and 30 % for NaBr:Cl and Y 3 Al 5 O 12 :Er crystals, respectively. In Y 3 Al 5 O 12 crystals, unlike NaCl-NaBr crystals, no noticeable anisotropy of damping is observed. The transVerse wave damping in impurity crystals has been shown to increase significantly with decreasing temperature and increasing the impurity concentration

Impurity investigations in the boundary layer of the DITE tokamak

International Nuclear Information System (INIS)

McCracken, G.M.; Partridge, J.W.; Erents, S.K.; Sofield, C.J.; Ferguson, S.M.

1982-01-01

The results obtained in the present investigation show large fluctuations both during discharges and from one discharge to the next. The radial density gradient of impurities in the boundary is not large. It is clear that the density and in particular dn/dt can have a strong effect on the impurity level. However there are apparently a number of other factors causing changes in impurity level which have not been well controlled in the present experiments. Possibilities include flaking from the walls, and changes in the level of the light impurities, oxygen and carbon, in the discharges. (orig./RW)

Investigation of impurity-helium solid phase decomposition

International Nuclear Information System (INIS)

Boltnev, R.E.; Gordon, E.B.; Krushinskaya, I.N.; Martynenko, M.V.; Pel'menev, A.A.; Popov, E.A.; Khmelenko, V.V.; Shestakov, A.F.

1997-01-01

The element composition of the impurity-helium solid phase (IHSP), grown by injecting helium gas jet, involving Ne, Ar, Kr, and Xe atoms and N 2 molecules, into superfluid helium, has been studied. The measured stoichiometric ratios, S = N H e / N I m, are well over the values expected from the model of frozen together monolayer helium clusters. The theoretical possibility for the freezing of two layers helium clusters is justified in the context of the model of IHSP helium subsystem, filled the space between rigid impurity centers. The process of decomposition of impurity-helium (IH)-samples taken out of liquid helium in the temperature range 1,5 - 12 K and the pressure range 10-500 Torr has been studied. It is found that there are two stages of samples decomposition: a slow stage characterized by sample self cooling and a fast one accompanied by heat release. These results suggest, that the IHSP consists of two types of helium - weakly bound and strongly bound helium - that can be assigned to the second and the first coordination helium spheres, respectively, formed around heavy impurity particles. A tendency for enhancement of IHSP thermo stability with increasing the impurity mass is observed. Increase of helium vapor pressure above the sample causes the improvement of IH sample stability. Upon destruction of IH samples, containing nitrogen atoms, a thermoluminescence induced by atom recombination has been detected in the temperature region 3-4,5 K. This suggests that numerous chemical reactions may be realized in solidified helium

Impurity studies in fusion devices using laser-fluorescence-spectroscopy

International Nuclear Information System (INIS)

Husinsky, W.R.

1980-08-01

Resonance fluorescence excitation of neutral atoms using tunable radiation from dye lasers offers a number of unique advantages for impurity studies in fusion devices. Using this technique, it is possible to perform local, time-resolved measurements of the densities and velocity distributions of metallic impurities in fusion devices without disturbing the plasma. Velocities are measured by monitoring the fluorescence intensity while tuning narrow bandwidth laser radiation through the Doppler - broadened absorbtion spectrum of the transition. The knowledge of the velocity distribution of neutral impurities is particularly useful for the determination of impurity introduction mechanisms. The laser fluorescence technique will be described in terms of its application to metallic impurities in fusion devices and related laboratory experiments. Particular attention will be given to recent results from the ISX-B tokamak using pulsed dye lasers where detection sensitivities for neutral Fe of 10 6 atoms/cm 3 with a velocity resolution of 600 m/sec (0.1 eV) have been achieved. Techniques for exciting plasma particles (H,D) will also be discussed

Orbit effects on impurity transport in a rotating plasma

International Nuclear Information System (INIS)

Wong, K.L.; Cheng, C.Z.

1988-01-01

In 1985, very high ion temperature plasmas were first produced in TFTR with co-injecting neutral beams in low current, low density plasmas. This mode of operation is called the energetic ion mode in which the plasma rotates at very high speed. It was found that heavy impurities injected into these plasmas diffused out very quickly. In this paper, the authors calculate the impurity ion orbits in a rotating tokamak plasma based on the equation of motion in the frame that rotates with the plasma. It is shown that heavy particles in a rotating plasma can drift away from magnetic surfaces significantly faster. Particle orbits near the surface of a rotating tokamak are also analyzed. During impurity injection experiments, freshly ionized impurities near the plasma surface are essentially stationary in the laboratory frame and they are counter-rotating in the plasma frame with co-beam injection. The results are substantiated by numeral particle simulation. The computer code follows the impurity guiding center positions by integrating the equation of motion with the second order predictor-corrector method

Resonant scattering on impurities in the quantum Hall effect

International Nuclear Information System (INIS)

Gurvitz, A.

1994-06-01

We developed a new approach to carrier transport between the edge states via resonant scattering on impurities, which is applicable both for short and long range impurities. A detailed analysis of resonant scattering on a single impurity is performed. The results used for study of the inter-edge transport by multiple resonant hopping via different impurities' site. We found the total conductance can be obtained from an effective Schroedinger equation with constant diagonal matrix elements in the Hamiltonian, where the complex non-diagonal matrix elements are the amplitudes of a carrier hopping between different impurities. It is explicitly shown how the complex phase leads to Aharonov-Bohm oscillations in the total conductance. Neglecting the contribution of self-crossing resonant-percolation trajectories, we found that the inter-edge carrier transport is similar to propagation in one-dimensional system with off-diagonal disorder. Then we demonstrated that each Landau band has an extended state Ε Ν , while all other states are localized, and the localization length behaves as L - 1 Ν (Ε) ∼ (Ε - Ε Ν ) 2 . (author)

Harmful situations, impure people: an attribution asymmetry across moral domains.

Science.gov (United States)

Chakroff, Alek; Young, Liane

2015-03-01

People make inferences about the actions of others, assessing whether an act is best explained by person-based versus situation-based accounts. Here we examine people's explanations for norm violations in different domains: harmful acts (e.g., assault) and impure acts (e.g., incest). Across four studies, we find evidence for an attribution asymmetry: people endorse more person-based attributions for impure versus harmful acts. This attribution asymmetry is partly explained by the abnormality of impure versus harmful acts, but not by differences in the moral wrongness or the statistical frequency of these acts. Finally, this asymmetry persists even when the situational factors that lead an agent to act impurely are stipulated. These results suggest that, relative to harmful acts, impure acts are linked to person-based attributions. Copyright © 2014 Elsevier B.V. All rights reserved.

A new and simple gravimetric method for determination of uranium

International Nuclear Information System (INIS)

Saxena, A.K.

1994-01-01

A new and simple gravimetric method for determining uranium has been described. Using a known quantity of uranyl nitrate as the test solution, an alcoholic solution of 2-amino-2-methyl 1:3 propanediol (AMP) was added slowly. A yellow precipitate was obtained which was filtered through ashless filter paper, washed with alcohol, dried and ignited at 800 degC for 4h. It gave a black powder as a product which was shown by X-ray diffraction to be U 3 O 8 . The percentage error was found in the range -0.09 to +0.89. (author). 8 refs., 1 tab

Impurity strength and impurity domain modulated frequency-dependent linear and second non-linear response properties of doped quantum dots

Energy Technology Data Exchange (ETDEWEB)

Datta, Nirmal Kumar [Department of Physics, Suri Vidyasagar College, Suri, Birbhum 731 101, West Bengal (India); Ghosh, Manas [Department of Chemistry, Physical Chemistry Section, Visva Bharati University, Santiniketan, Birbhum 731 235, West Bengal (India)

2011-08-15

We explore the pattern of frequency-dependent linear and second non-linear optical responses of repulsive impurity doped quantum dots harmonically confined in two dimensions. The dopant impurity potential chosen assumes a Gaussian form and it is doped into an on-center location. The quantum dot is subject to a periodically oscillating external electric field. For some fixed values of transverse magnetic field strength ({omega}{sub c}) and harmonic confinement potential ({omega}{sub 0}), the influence of impurity strength (V{sub 0}) and impurity domain ({xi}) on the diagonal components of the frequency-dependent linear ({alpha}{sub xx} and {alpha}{sub yy}) and second non-linear ({gamma}{sub xxxx} and {gamma}{sub yyyy}) responses of the dot are computed through a linear variational route. The investigations reveal that the optical responses undergo enhancement with increase in both V{sub 0} and {xi} values. However, in the limitingly small dopant strength regime one observes a drop in the optical responses with increase in V{sub 0}. A time-average rate of energy transfer to the system is often invoked to support the findings. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Boron, nitrogen, and nickel impurities in GeC nanoribbons: A first-principles investigation

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhuo; Li, Yangping, E-mail: liyp@nwpu.edu.cn; Liu, Zhengtang

2017-07-01

Highlights: • The impurities preferentially substitutes the Ge atom at the ribbon edge. • The impurities could result in a reduction of the band gap of 7-AGeCNR. • The impurities turns the metallic behavior of 4-ZGeCNR into semiconductor. • The impurities could change the magnetic moment of 4-ZGeCNR. • The impurities could introduce magnetic moments into the non-magnetic 7-AGeCNR. - Abstract: Using first-principles calculations based on the density functional theory we investigated the structural, electronic and magnetic properties of substitutional boron, nitrogen, and nickel impurities in germanium carbide (GeC) nanoribbons. Hydrogen terminated GeC ribbons with armchair and zigzag edges are considered here. We observed that all three impurities preferentially substitutes the Ge atom at the ribbon edge. In addition, the electronic band structures of the doped systems indicate that (i) the impurities could introduce impurity bands in the band gap and resulting in a reduction of the band gap of 7-AGeCNR, (ii) the metallic behavior of 4-ZGeCNR turns into semiconductor because of the incorporation of the impurities, (iii) the impurities could change the magnetic moment of 4-ZGeCNR and even introduce magnetic moment into the non-magnetic 7-AGeCNR.

Weak Localization and Antilocalization in Topological Materials with Impurity Spin-Orbit Interactions

Science.gov (United States)

Hankiewicz, Ewelina M.; Culcer, Dimitrie

2017-01-01

Topological materials have attracted considerable experimental and theoretical attention. They exhibit strong spin-orbit coupling both in the band structure (intrinsic) and in the impurity potentials (extrinsic), although the latter is often neglected. In this work, we discuss weak localization and antilocalization of massless Dirac fermions in topological insulators and massive Dirac fermions in Weyl semimetal thin films, taking into account both intrinsic and extrinsic spin-orbit interactions. The physics is governed by the complex interplay of the chiral spin texture, quasiparticle mass, and scalar and spin-orbit scattering. We demonstrate that terms linear in the extrinsic spin-orbit scattering are generally present in the Bloch and momentum relaxation times in all topological materials, and the correction to the diffusion constant is linear in the strength of the extrinsic spin-orbit. In topological insulators, which have zero quasiparticle mass, the terms linear in the impurity spin-orbit coupling lead to an observable density dependence in the weak antilocalization correction. They produce substantial qualitative modifications to the magnetoconductivity, differing greatly from the conventional Hikami-Larkin-Nagaoka formula traditionally used in experimental fits, which predicts a crossover from weak localization to antilocalization as a function of the extrinsic spin-orbit strength. In contrast, our analysis reveals that topological insulators always exhibit weak antilocalization. In Weyl semimetal thin films having intermediate to large values of the quasiparticle mass, we show that extrinsic spin-orbit scattering strongly affects the boundary of the weak localization to antilocalization transition. We produce a complete phase diagram for this transition as a function of the mass and spin-orbit scattering strength. Throughout the paper, we discuss implications for experimental work, and, at the end, we provide a brief comparison with transition metal

Identification and Structural Characterization of Unidentified Impurity in Bisoprolol Film-Coated Tablets

Directory of Open Access Journals (Sweden)

Ivana Mitrevska

2017-01-01

Full Text Available The aim of this study is the identification, structural characterization, and qualification of a degradation impurity of bisoprolol labeled as Impurity RRT 0.95. This degradation product is considered as a principal thermal degradation impurity identified in bisoprolol film-coated tablets. The impurity has been observed in the stress thermal degradation study of the drug product. Using HPLC/DAD/ESI-MS method, a tentative structure was assigned and afterwards confirmed by detailed structural characterization using NMR spectroscopy. The structure of the target Impurity RRT 0.95 was elucidated as phosphomonoester of bisoprolol, having relative molecular mass of 406 (positive ionization mode. The structural characterization was followed by qualification of Impurity RRT 0.95 using several different in silico methodologies. From the results obtained, it can be concluded that no new structural alerts have been generated for Impurity RRT 0.95 relative to the parent compound bisoprolol. The current study presents an in-depth analysis of the full characterization and qualification of an unidentified impurity in a drug product with the purpose of properly defining the quality specification of the product.

Analysis methods for fast impurity ion dynamics data

International Nuclear Information System (INIS)

Den Hartog, D.J.; Almagri, A.F.; Prager, S.C.; Fonck, R.J.

1994-08-01

A high resolution spectrometer has been developed and used on the MST reversed-field pinch (RFP) to measure passively impurity ion temperatures and flow velocities with 10 μs temporal resolution. Such measurements of MHD-scale fluctuations are particularly relevant in the RFP because the flow velocity fluctuation induced transport of current (the ''MHD dynamo'') may produce the magnetic field reversal characteristic of an RFP. This instrument will also be used to measure rapid changes in the equilibrium flow velocity, such as occur during locking and H-mode transition. The precision of measurements made to date is <0.6 km/s. The authors are developing accurate analysis techniques appropriate to the reduction of this fast ion dynamics data. Moment analysis and curve-fitting routines have been evaluated for noise sensitivity and robustness. Also presented is an analysis method which correctly separates the flux-surface average of the correlated fluctuations in u and B from the fluctuations due to rigid shifts of the plasma column

Characterization of intermittency of impurity turbulent transport in tokamak edge plasmas

International Nuclear Information System (INIS)

Futatani, S.; Benkadda, S.; Nakamura, Y.; Kondo, K.

2008-01-01

The statistical properties of impurity transport of a tokamak edge plasma embedded in a dissipative drift-wave turbulence are investigated using structure function analysis. The impurities are considered as a passive scalar advected by the plasma flow. Two cases of impurity advection are studied and compared: A decaying impurities case (given by a diffusion-advection equation) and a driven case (forced by a mean scalar gradient). The use of extended self-similarity enables us to show that the relative scaling exponent of structure functions of impurity density and vorticity exhibit similar multifractal scaling in the decaying case and follows the She-Leveque model. However, this property is invalidated for the impurity driven advection case. For both cases, potential fluctuations are self-similar and exhibit a monofractal scaling in agreement with Kolmogorov-Kraichnan theory for two-dimensional turbulence. These results obtained with a passive scalar model agree also with test-particle simulations.

Gravimetric determination of hafnium through its arsenate in carbide and boride of hafnium

International Nuclear Information System (INIS)

Rasulbekova, R.A.; Mamedov, I.A.

1976-01-01

A gravimetric method of determining hafnium through hydroarsenate has been recommended. The method differs from the known ones by its simplicity and by the recalculation coefficient which is more than by 50% smaller than that used in preparing a weight form of HfO 2 . Upon development of gravimetric determination of hafnium through hydro-and pyroarsenate, an investigation has been conducted with the aim to find some physico-chemical constants of hafnium hydroarsenate. The weighed amount of hafnium hydroarsenate is dissolved in sulphuric acid (2:5). The precipitate of hafnium hydroarsenate has been studied for recording infrared absorption spectra. Thermographic analysis of the precipitate has been performed. Thermogram reveals endothermal effect at 105 deg C and exothermal at 840 deg C. Water solubility of hafnium has been determined equal to 1.75x10 6 g mol/l. The corresponding solubility product of the precipitate has been calculated which is 2.1x10 -17 . It is shown that the method possesses certain selectivity, sufficient accuracy, and is rather fast. It has been established that determination can be performed in the presence of excess amounts of ions

Negative compressibility observed in graphene containing resonant impurities

International Nuclear Information System (INIS)

Chen, X. L.; Wang, L.; Li, W.; Wang, Y.; He, Y. H.; Wu, Z. F.; Han, Y.; Zhang, M. W.; Xiong, W.; Wang, N.

2013-01-01

We observed negative compressibility in monolayer graphene containing resonant impurities under different magnetic fields. Hydrogenous impurities were introduced into graphene by electron beam (e-beam) irradiation. Resonant states located in the energy region of ±0.04 eV around the charge neutrality point were probed in e-beam-irradiated graphene capacitors. Theoretical results based on tight-binding and Lifshitz models agreed well with experimental observations of graphene containing a low concentration of resonant impurities. The interaction between resonant states and Landau levels was detected by varying the applied magnetic field. The interaction mechanisms and enhancement of the negative compressibility in disordered graphene are discussed.

Modeling of impurity transport in the core plasma

International Nuclear Information System (INIS)

Hulse, R.A.

1992-01-01

This paper presents a brief overview of computer modeling of impurity transport in the core region of controlled thermonuclear fusion plasmas. The atomic processes of importance in these high temperature plasmas and the numerical formulation of the model are described. Selected modeling examples are then used to highlight some features of the physics of impurity behavior in large tokamak fusion devices, with an emphasis on demonstrating the sensitivity of such modeling to uncertainties in the rate coefficients used for the atomic processes. This leads to a discussion of current requirements and opportunities for generating the improved sets of comprehensive atomic data needed to support present and future fusion impurity modeling studies

Electronic structure of deep impurity centers in silicon

International Nuclear Information System (INIS)

Oosten, A.B. van.

1989-01-01

This thesis reports an experimental study of deep level impurity centers in silicon, with much attention for theoretical interpretation of the data. A detailed picture of the electronic structure of several centers was obtained by magnetic resonance techniques, such as electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR) and field scanned ENDOR (FSE). The thesis consists of two parts. The first part deals with chalcogen (sulfur, selenium and tellurium) related impurities, which are mostly double donors. The second part is about late transition metal (nickel, palladium and platinum) impurities, which are single (Pd,Pt) or double (Ni) acceptor centers. (author). 155 refs.; 51 figs.; 23 tabs

Tectonic evolution of the Paranoá basin: New evidence from gravimetric and stratigraphic data

Science.gov (United States)

Martins-Ferreira, Marco Antonio Caçador; Campos, José Eloi Guimarães; Von Huelsen, Monica Giannoccaro

2018-06-01

Field gravimetric and stratigraphic surveys were conducted with the aim to constraint the mechanisms responsible for the initiation of the Stenian-Tonian Paranoá basin, central Brazil, a subject not yet studied in detail. The Paranoá Group crops out in the external zone of the Brasília Belt, a Neoproterozoic orogen in the western margin of the São Francisco Craton. Detailed geological mapping confirmed the existence of a regional scale fault that controlled sedimentation of the Paranoá Group during the deposition of its basal formations, revealing important details about basin initiation and early evolution. Gravimetric modeling indicates the existence of paleorift structures beneath the Paranoá sequence in the study area. Results from both stratigraphic and gravimetric surveys show strong evidence of mechanical subsidence by faulting during basin initiation. Unsorted, angular, clasts cut by quartz veins and brecciated boulders present in the basal conglomerate, support this hypothesis. Basin initiation faults coincide with deeper paleorift faults and are thus interpreted as reactivations of the older Statherian Araí Rift. The reactivations favored an initial regime of mechanical subsidence, dominated by the development of epirogenic arches subsiding at different rates. Apart from faulting activity, the post-basal sequence presents no evidence of rift environment in the strict sense. Besides, the great lateral continuity and relatively constant thickness of facies, indicate that an initial mechanic subsidence rapidly gave way to flexural subsidence during subsequent stages of basin evolution. The Paranoá Group do not present reliable characteristics that would allow its strict classification as a passive margin. Its main stratigraphic characteristics, tectonic location and basement architecture, indicate that the Paranoá Group was deposited in a cratonic margin basin, and may have been either connected to a passive margin basin at times of sea level rise

Tokamak impurity-control techniques

International Nuclear Information System (INIS)

Schmidt, J.A.

1980-01-01

A brief review is given of the impurity-control functions in tokamaks, their relative merits and disadvantages and some prominent edge-interaction-control techniques, and there is a discussion of a new proposal, the particle scraper, and its potential advantages. (author)

Sodium sampling and impurities determination

International Nuclear Information System (INIS)

Docekal, J.; Kovar, C.; Stuchlik, S.

1980-01-01

Samples may be obtained from tubes in-built in the sodium facility and further processed or they are taken into crucibles, stored and processed later. Another sampling method is a method involving vacuum distillation of sodium, thus concentrating impurities. Oxygen is determined by malgamation, distillation or vanadium balance methods. Hydrogen is determined by the metal diaphragm extraction, direct extraction or amalgamation methods. Carbon is determined using dry techniques involving burning a sodium sample at 1100 degC or using wet techniques by dissolving the sample with an acid. Trace amounts of metal impurities are determined after dissolving sodium in ethanol. The trace metals are concentrated and sodium excess is removed. (M.S.)

A cost-effective technique for integrating personal radiation dose assessment with personal gravimetric sampling

International Nuclear Information System (INIS)

Strydom, R.; Rolle, R.; Van der Linde, A.

1992-01-01

During recent years there has been an increasing awareness internationally of radiation levels in the mining and milling of radioactive ores, including those from non-uranium mines. A major aspect of radiation control is concerned with the measurement of radiation levels and the assessment of radiation doses incurred by individual workers. Current techniques available internationally for personnel monitoring of radiation exposures are expensive and there is a particular need to reduce the cost of personal radiation monitoring in South African gold mines because of the large labour force employed. In this regard the obvious benefits of integrating personal radiation monitoring with existing personal monitoring systems already in place in South African gold mines should be exploited. A system which can be utilized for this purpose is personal gravimetric sampling. A new cost-effective technique for personal radiation monitoring, which can be fully integrated with the personal gravimetric sampling strategy being implemented on mines, has been developed in South Africa. The basic principles of this technique and its potential in South African mines are described. 9 refs., 7 figs

Near infrared spectrometry for faecal fat measurement: comparison with conventional gravimetric and titrimetric methods.

Science.gov (United States)

Benini, L; Caliari, S; Guidi, G C; Vaona, B; Talamini, G; Vantini, I; Scuro, L A

1989-01-01

This investigation was aimed at comparing a new method for measuring faecal fat excretion, carried out with a semi-automated instrument by using near infrared analysis (NIRA), with the traditional titrimetric (Van de Kamer) and gravimetric (Sobel) methods. Near infrared analysis faecal fat was assayed on the three day stool collection from 118 patients (68 chronic pancreatitis, 19 organic diseases of the gastrointestinal tract, 19 alcoholic liver disease, 12 functional gastrointestinal disorders). A strict linear correlation was found between NIRA and both the titrimetric (r = 0.928, p less than 0.0001) and the gravimetric (r = 0.971, p less than 0.0001) methods. On homogenised faeces, a mean coefficient of variation of 2.1 (SD 1.71)% was found. Before homogenisation (where a mean coefficient of variation of 7% was found) accurate results were obtained when the mean of five measurements was considered. In conclusion, the assay of faecal fat excretion by the near infrared reflessometry appears a simple, rapid and reliable method for measuring steatorrhoea. PMID:2583563

Determination of uranium in coated fuel particle compact by potassium fluoride fusion-gravimetric method

International Nuclear Information System (INIS)

Ito, Mitsuo; Iso, Shuichi; Hoshino, Akira; Suzuki, Shuichi.

1992-03-01

Potassium fluoride-gravimetric method has been developed for the determination of uranium in TRISO type-coated fuel particle compact. Graphite matrix in the fuel compact is burned off by heating it in a platinum crucible at 850degC. The coated fuel particles thus obtained are decomposed by fusion with potassium fluoride at 900degC. The melt was dissolved with sulfuric acid. Uranium is precipitated as ammonium diuranate, by passing ammonia gas through the solution. The resulting precipitate is heated in a muffle furnace at 850degC, to convert uranium into triuranium octoxide. Uranium in the triuranium octoxide was determined gravimetrically. Ten grams of caoted fuel particles were completely decomposed by fusion with 50 g of potassium fluoride at 900degC for 3 hrs. Analytical result for uranium in the fuel compact by the proposed method was 21.04 ± 0.05 g (n = 3), and was in good agreement with that obtained by non-destructive γ-ray measurement method : 21.01 ± 0.07 g (n = 3). (author)

Influence of the impurity-defect and impurity-impurity interactions on the crystalline silicon solar cells conversion efficiency; Influence des interactions impurete-defaut et impurete-impurete sur le rendement de conversion des cellules photovoltaiques au silicium cristallin

Energy Technology Data Exchange (ETDEWEB)

Dubois, S

2007-05-15

This study aims at understanding the influence of the impurity - defect interaction on the silicon solar cell performances. We studied first the case of single-crystalline silicon. We combined numerical simulations and experimental data providing new knowledge concerning metal impurities in silicon, to quantify the evolution of the conversion efficiency with the impurity concentration. Mainly due to the gettering effects, iron appears to be quite well tolerated. It is not the case for gold, diffusing too slowly. Hydrogenation effects were limited. We transposed then this study toward multi-crystalline silicon. Iron seems rather well tolerated, due to the gettering effects but also due to the efficiency of the hydrogenation. When slow diffusers are present, multi crystalline silicon is sensitive to thermal degradation. n-type silicon could solve this problem, this material being less sensitive to metal impurities. (author)

Impurity states in two - and three-dimensional disordered systems

International Nuclear Information System (INIS)

Silva, A.F. da; Fabbri, M.

1984-01-01

We investigate the microscopic structure of the impurity states in two-and three-dimensional (2D and 3d) disordered systems. A cluster model is outlined for the donor impurity density of states (DIDS) of doped semiconductors. It is shown that the impurity states are very sensitive to a change in the dimensionality of the system, i.e from 3D to 2D system. It is found that all eigenstates become localized in 2D disordered system for a large range of concentration. (Author) [pt

Extraction process for removing metallic impurities from alkalide metals

Science.gov (United States)

Royer, Lamar T.

1988-01-01

A development is described for removing metallic impurities from alkali metals by employing an extraction process wherein the metallic impurities are extracted from a molten alkali metal into molten lithium metal due to the immiscibility of the alkali metals in lithium and the miscibility of the metallic contaminants or impurities in the lithium. The purified alkali metal may be readily separated from the contaminant-containing lithium metal by simple decanting due to the differences in densities and melting temperatures of the alkali metals as compared to lithium.

Impurity states in two-and three-dimensional disordered systems

International Nuclear Information System (INIS)

Silva, A.F. da; Fabbri, M.

1984-04-01

The microscopic structure of the impurity states in two-and three-dimensional (2D and 3D) disordered systems is investigated. A cluster model is outlined for the donor impurity density of states (DIDS) of doped semiconductors. It is shown that the impurity states are very sensitive to a change in the dimensionality of the system, i.e., from 3D to 2D system. It is found that all eigenstates become localized in 2D disordered system for a large range of concentration. (Author) [pt

The Comparison Of Silicon Analysis For The Uranium Silicide Fuel Using Spectrophotometrical And Gravimetrical Methods

International Nuclear Information System (INIS)

Putro, P. K.; Suripto, A.; Putra, S.; Gunanjar

1996-01-01

The analysis of silicon content in the uranium silicide fuel spectro-photometrical and gravimetrical method have been performed. The nitrous oxide-acetylene was used in the atomic absorption spectrophotometry (AAS) on the wave length of 251.6 nm, and the mixture of ammonium hepta molybdate complexes and SnC1 2 as reductor were applied during analysis by UV-VIS spectrophotometry (UV-VIS) on the wave length of 757.5 mm. The reagent of HCLO 4 and HNO 3 were used for determining Si content by gravimetrical methods. The results of this comparison is as follows: the accuracy result is around 96.37 % + 0.24 % for the Si concentration up to 300 ppm (the AAS), is 138.60 % = 0.43 % for the Si concentration range between 0.1-1.5 ppm (UV-VIS), and is 51.13 % + 0.8 % for 1 gram of Si (gravimetry). The results also show that the lowest analytical error is obtained by AAS method

Effect of HEH[EHP] impurities on the ALSEP solvent extraction process

Energy Technology Data Exchange (ETDEWEB)

Holfeltz, Vanessa E. [Nuclear Chemistry and Engineering Group, Pacific Northwest National Laboratory, Richland, WA, USA; School of Nuclear Science and Engineering, Oregon State University, Corvallis, OR, USA; Campbell, Emily L. [Nuclear Chemistry and Engineering Group, Pacific Northwest National Laboratory, Richland, WA, USA; Peterman, Dean R. [Aqueous Separations and Radiochemistry Department, Idaho National Laboratory, Idaho Falls, ID, USA; Standaert, Robert F. [Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Department of Biochemistry & amp, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA; Biology & amp, Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Shull Wollan Center — a Joint Institute for Neutron Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Paulenova, Alena [School of Nuclear Science and Engineering, Oregon State University, Corvallis, OR, USA; Lumetta, Gregg J. [Nuclear Chemistry and Engineering Group, Pacific Northwest National Laboratory, Richland, WA, USA; Levitskaia, Tatiana G. [Nuclear Chemistry and Engineering Group, Pacific Northwest National Laboratory, Richland, WA, USA

2017-12-20

In solvent extraction processes, organic phase impurities can negatively impact separation factors, hydrolytic performance, and overall system robustness. This affects the process-level viability of a separation concept and necessitates knowledge of the behavior and mechanisms to control impurities in the solvent. The most widespread way through which impurities are introduced into a system is through impure extractants and/or diluents used to prepare the solvent, and often development of new purification schemes to achieve the desired level of purity is needed. In this work, the acidic extractant, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP])—proposed for application in extractive processes aimed at separating trivalent minor actinides from lanthanides and other fission products—is characterized with respect to its common impurities and their impact on Am(III) stripping in the Actinide Lanthanide SEParation (ALSEP) system. To control impurities in HEH[EHP], existing purification technologies commonly applied for the acidic organophosphorus reagents are reviewed, and a new method specific to HEH[EHP] purification is presented.

Tight-Binding Description of Impurity States in Semiconductors

Science.gov (United States)

Dominguez-Adame, F.

2012-01-01

Introductory textbooks in solid state physics usually present the hydrogenic impurity model to calculate the energy of carriers bound to donors or acceptors in semiconductors. This model treats the pure semiconductor as a homogeneous medium and the impurity is represented as a fixed point charge. This approach is only valid for shallow impurities…

BWR water chemistry impurity studies

International Nuclear Information System (INIS)

Ljungberg, L.G.; Korhonen, S.; Renstroem, K.; Hofling, C.G.; Rebensdorff, B.

1990-03-01

Laboratory studies were made on the effect of water impurities on environmental cracking in simulated BWR water of stainless steel, low alloy steel and nickel-base alloys. Constant elongation rate tensile (CERT) tests were run in simulated normal water chemistry (NWC), hydrogen water chemistry (HWC), or start-up environment. Sulfate, chloride and copper with chloride added to the water at levels of a fraction of a ppM were found to be extremely deleterious to all kinds of materials except Type 316 NG. Other detrimental impurities were fluoride, silica and some organic acids, although acetic acid was beneficial. Nitrate and carbon dioxide were fairly inoccuous. Corrosion fatigue and constant load tests on compact tension specimens were run in simulated normal BWR water chemistry (NWC) or hydrogen water chemistry (HWC), without impurities or with added sulfate or carbon dioxide. For sensitized Type 304 SS in NWC, 0.1 ppM sulfate increased crack propagation rates in constant load tests by up to a factor of 100, and in fatigue tests up to a factor of 10. Also, cracking in Type 316 nuclear grade SS and Alloy 600 was enhanced, but to a smaller degree. Carbon dioxide was less detrimental than sulfate. 3 figs., 4 tabs

A problem in gravimetric method for the determination of rare earth elements as oxide after the fluoride separation

International Nuclear Information System (INIS)

Takada, Kunio

1979-01-01

For the gravimetric determination of lanthanum, it was precipitated as fluoride and converted to oxide by igniting (ca. 930 0 C) in a town gas flame. However, the oxidation of lanthanum fluoride by ignition was incomplete, the major part of the precipitate being converted to oxyfluoride (LaOF) and a mixture of oxide and oxyfluoride resulted. Therefore, analytical results were generally (5 -- 7)% higher than theoretically expected. The lanthanum fluoride became converted into the oxide by repeating ignition (ca. 1070 0 C) three times, each for (30 -- 40)min. However, the weight was lower than that of the corresponding sesquioxide, La 2 O 3 . Except for ytterbium and lutetium, gravimetric results as oxides for the other rare earth elements (Y, Pr, Nd, Sm, Eu and Gd) were higher than theoretical values. Therefore, the precipitation of the rare earth elements as fluoride and the subsequent determination as oxide by ignition of the fluoride could not be recommended as the gravimetric method for the rare earths. In order to obtain accurate results for major to minor amounts of the rare earth elements, an EDTA titration at pH 6 should be used after the dissolution of fluoride in acid, if the fluoride precipitation separation is involved. (author)

STM tunneling through a quantum wire with a side-attached impurity

International Nuclear Information System (INIS)

Kwapinski, T.; Krawiec, M.; Jalochowski, M.

2008-01-01

The STM tunneling through a quantum wire (QW) with a side-attached impurity (atom, island) is investigated using a tight-binding model and the non-equilibrium Keldysh Green function method. The impurity can be coupled to one or more QW atoms. The presence of the impurity strongly modifies the local density of states of the wire atoms, thus influences the STM tunneling through all the wire atoms. The transport properties of the impurity itself are also investigated mainly as a function of the wire length and the way it is coupled to the wire. It is shown that the properties of the impurity itself and the way it is coupled to the wire strongly influence the STM tunneling, the density of states and differential conductance

Effects of impurities on crystal growth in fructose crystallization

Science.gov (United States)

Chu, Y. D.; Shiau, L. D.; Berglund, K. A.

1989-10-01

The influence of impurities on the crystallization of anhydrous fructose from aqueous solution was studied. The growth kinetics of fructose crystals in the fructose-water-glucose and fructose-water-difructose dianhydrides systems were investigated using photomicroscopic contact nucleation techniques. Glucose is the major impurity likely to be present in fructose syrup formed during corn wet milling, while several difructose dianhydrides are formed in situ under crystallization conditions and have been proposed as a cause in the decrease of overall yields. Both sets of impurities were found to cause inhibition of crystal growth, but the mechanisms responsible in each case are different. It was found that the presence of glucose increases the solubility of fructose in water and thus lowers the supersaturation of the solution. This is probably the main effect responsible for the decrease of crystal growth. Since the molecular structures of difructose dianhydrides are similar to that of fructose, they are probably "tailor-made" impurities. The decrease of crystal growth is probably caused by the incorporation of these impurities into or adsorption to the crystal surface which would accept fructose molecules in the orientation that existed in the difructose dianhydride.

Spectroscopic Measurements of Impurity Spectra on the EAST Tokamak

International Nuclear Information System (INIS)

Fu Jia; Li Yingying; Shi Yuejiang; Wang Fudi; Zhang Wei; Lv Bo; Huang Juan; Wan Baonian; Zhou Qian

2012-01-01

Ultraviolet (UV) and visible impurity spectra (200∼750 nm) are commonly used to study plasma and wall interactions in magnetic fusion plasmas. Two optical multi-channel analysis (OMA) systems have been installed for the UV-visible spectrum measurement on EAST. These two OMA systems are both equipped with the Czerny-Turner (C-T) type spectrometer. The upper vacuum vessel and inner divertor baffle can be viewed simultaneously through two optical lenses. The OMA1 system is mainly used for multi-impurity lines radiation measurement. A 280 nm wavelength range can be covered by a 300 mm focal length spectrometer equipped with a 300 grooves/mm grating. The Dα/Hα line shapes can be resolved by the OMA2 system. The focal length is 750 mm. The spectral resolution can be up to 0.01 nm using a 1800 grooves/mm grating. The impurity behaviour and hydrogen ratio evolution after boroniztion, lithium coating, and siliconization are compared. Lithium coating has shown beneficial effects on the reduction of edge recycling and low Z impurity (C, O) influx. The impurity expelling effect of the divertor configuration is also briefly discussed through multi-channels observation of OMA1 system. (magnetically confined plasma)

The use of cerium(IV) phosphate for the gravimetric determination and separation of cerium

International Nuclear Information System (INIS)

Masin, V.; Dolezal, J.

1978-01-01

A method for the gravimetric determination of cerium as Ce 3 (PO 4 ) 4 is described. Cerium can be separated from many metals in this form, as well as from permanganate and dichromate; the cerium separated can then be titrated with iron(II) solution. The method was verified for the determination of cerium in a rare earth concentrate. (Auth.)

Design and realization of the high-precision weighing systems as the gravimetric references in PTB's national water flow standard

International Nuclear Information System (INIS)

Engel, Rainer; Beyer, Karlheinz; Baade, Hans-Joachim

2012-01-01

PTB's ‘Hydrodynamic Test Field’, which represents a high-accuracy water flow calibration facility, serves as the national primary standard for liquid flow measurands. As the core reference device of this flow facility, a gravimetric standard has been incorporated, which comprises three special-design weighing systems: 300 kg, 3 tons and 30 tons. These gravimetric references were realized as a combination of a strain-gauge-based and an electromagnetic-force-compensation load-cell-based balance, each. Special emphasis had to be placed upon the dynamics design of the whole weighing system, due to the high measurement resolution and the dynamic behavior of the weighing systems, which are dynamically affected by mechanical vibrations caused by environmental impacts, flow machinery operation, flow noise in the pipework and induced wave motions in the weigh tanks. Taking into account all the above boundary conditions, the design work for the gravimetric reference resulted in a concrete foundation ‘rock’ of some 300 tons that rests on a number of vibration isolators. In addition to these passively operating vibration isolators, the vibration damping effect is enhanced by applying an electronic level regulation device. (paper)

Properties of magnetic impurities embedded into an anisotropic Heisenberg chain with spin gap

International Nuclear Information System (INIS)

Schlottmann, P.

2000-01-01

We consider a U(1)-invariant model consisting of the integrable anisotropic easy-axis Heisenberg chain of arbitrary spin S embedding an impurity of spin S'. The host chain has a spin gap for all values of S. The ground state properties and the elementary excitations of the host are studied as a function of the anisotropy and the magnetic field. The impurity is located on a link of the chain and interacts only with both neighboring sites. The coupling of the impurity to the lattice can be tuned by the impurity rapidity p 0 (usually playing the role of the Kondo coupling). The impurity model is then integrable as a function of two continuous parameters (the anisotropy and the impurity rapidity) and two discrete variables (the spins S and S'). The Bethe ansatz equations are derived and used to obtain the magnetization of the impurity. The impurity magnetization is non-universal as a function of p 0 . For small fields the impurity magnetization is determined by the spin gap and the van Hove singularity of the rapidity band. For an overcompensated impurity (S'< S) at intermediate fields there is a crossover to non-Fermi-liquid behavior remnant from the suppressed quantum critical point

Impurity production and transport at the JET belt limiter

International Nuclear Information System (INIS)

Pitcher, C.S.; McCracken, G.M.; Strangeby, P.C.; Toronto Univ., ON; Summers, D.D.R.

1989-01-01

Under certain operating conditions in JET the impurity content of the discharge can be high, thus reducing the fusion reaction rate through the dilution of the hydrogenic fuel. The dilution in most discharges is predominantly due to carbon impurities. In order to understand how carbon impurities are produced and transported into the plasma, detailed measurements with interference filters centered on intense spectral lines of the low ionization states of carbon (C I, C II, C III) as well as the fuel species (Dα) and helium (He I). (author) 6 refs., 4 figs

Hopping conductivity via deep impurity states in InP

International Nuclear Information System (INIS)

Kuznetsov, V.P.; Messerer, M.A.; Omel'yanovskij, Eh.M.

1984-01-01

Hopping (epsilon 3 ) and Mott conductivities via deep impurity compounds with localization radius below 10 A have been studied using as an example Mn in InP. It is shown, that the existing theory of hopping conductivity in low-alloyed semiconductors with Na 3 << 1 can be Used for the case of deep centres as successfully as for the case of insignificant hydrogen-like impurities. Fundamental parameters of the theory: localization radius of wave function of deep impurities, state density near the Fermi level, mean hop length, are determined

The impact of impurities on long-term PEMFC performance

Energy Technology Data Exchange (ETDEWEB)

Garzon, Fernando H [Los Alamos National Laboratory; Lopes, Thiago [Los Alamos National Laboratory; Rockward, Tommy [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory; Sansinena, Jose - Maria [Los Alamos National Laboratory; Kienitz, Brian [LLNL

2009-06-23

Electrochemical experimentation and modeling indicates that impurities degrade fuel cell performance by a variety of mechanisms. Electrokinetics may be inhibited by catalytic site poisoning from sulfur compounds and CO and by decreased local proton activity and mobility caused by the presence of foreign salt cations or ammonia. Cation impurity profiles vary with current density, valence and may change local conductivity and water concentrations in the ionomer. Nitrogen oxides and ammonia species may be electrochemically active under fuel cell operating conditions. The primary impurity removal mechanisms are electrooxidation and water fluxes through the fuel cell.

Behavior of arsenic impurity at antimony electric precipitation

International Nuclear Information System (INIS)

Kim, G.N.; Rakhmanov, A.

2001-01-01

In the paper the arsenic impurity electrochemical behavior and it purification from antimony by electric precipitation out of fluoride solutions was studied. For this the arsenic sample with mass 0.003-0.006 g has been irradiated at the WWR-SM nuclear reactor during 3-5 hour in the thermal neutron flux 10 13 n/cm 2 s, after 24 h keeping the sample has being dissolved in the concentrated nitric acid, and then it has been evaporated several times with distillation water addition up to wet precipitation state. It is shown, that arsenic impurity behavior character in the antimony electric precipitation out to fluoride electrolyte depends on the electrolyte content, electrolysis conditions, arsenic valency state in arsenic impurity existence in the five-valency state its joint electric reduction with antimony is practically not observing. In the case the arsenic being in three-valency state, it joint electric reduction with antimony is taking place. In this time the electrolytic antimony contents arsenic impurities less in dozen time than initial material

Determination of correction coefficients for quantitative analysis by mass spectrometry. Application to uranium impurities analysis; Recherche des coefficients de correction permettant l'analyse quantitative par spectrometrie de masse. Application a l'analyse d'impuretes dans l'uranium

Energy Technology Data Exchange (ETDEWEB)

Billon, J P [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

1970-07-01

Some of basic principles in spark source mass spectrometry are recalled. It is shown how this method can lead to quantitative analysis when attention is paid to some theoretical aspects. A time constant relation being assumed between the analysed solid sample and the ionic beam it gives we determined experimental relative sensitivity factors for impurities in uranium matrix. Results being in fairly good agreement with: an unelaborate theory on ionization yield in spark-source use of theoretically obtained relative sensitivity factors in uranium matrix has been developed. (author) [French] Apres avoir rappele quelques principes fondamentaux regissant la spectrometrie de masse a etincelles, nous avons montre que moyennant un certain nombre de precautions, il etait possible d'utiliser cette methode en analyse quantitative. Ayant admis qu'il existait une relation constante dans le temps entre l'echantillon solide analyse et le faisceau ionique qui en est issu, nous avons d'abord entrepris de determiner des coefficients de correction experimentaux pour des matrices d'uranium. Les premiers resultats pratiques semblant en accord avec une theorie simple relative au rendement d'ionisation dans la source a etincelles, nous avons etudie la possibilite d'appliquer directement les coefficients theoriques ainsi definis, l'application etant toujours faite sur des matrices d'uranium. (auteur)

Time-Resolved Gravimetric Method To Assess Degassing of Roasted Coffee.

Science.gov (United States)

Smrke, Samo; Wellinger, Marco; Suzuki, Tomonori; Balsiger, Franz; Opitz, Sebastian E W; Yeretzian, Chahan

2018-05-30

During the roasting of coffee, thermally driven chemical reactions lead to the formation of gases, of which a large fraction is carbon dioxide (CO 2 ). Part of these gases is released during roasting while part is retained inside the porous structure of the roasted beans and is steadily released during storage or more abruptly during grinding and extraction. The release of CO 2 during the various phases from roasting to consumption is linked to many important properties and characteristics of coffee. It is an indicator for freshness, plays an important role in shelf life and in packaging, impacts the extraction process, is involved in crema formation, and may affect the sensory profile in the cup. Indeed, and in view of the multiple roles it plays, CO 2 is a much underappreciated and little examined molecule in coffee. Here, we introduce an accurate, quantitative, and time-resolved method to measure the release kinetics of gases from whole beans and ground coffee using a gravimetric approach. Samples were placed in a container with a fitted capillary to allow gases to escape. The time-resolved release of gases was measured via the weight loss of the container filled with coffee. Long-term stability was achieved using a customized design of a semimicro balance, including periodic and automatic zero value measurements and calibration procedures. The novel gravimetric methodology was applied to a range of coffee samples: (i) whole Arabica beans and (ii) ground Arabica and Robusta, roasted to different roast degrees and at different speeds (roast air temperatures). Modeling the degassing rates allowed structural and mechanistic interpretation of the degassing process.

Quenching of overcompensated Kondo impurities via channel asymmetry

International Nuclear Information System (INIS)

Schlottmann, P.; Lee, K.

1996-01-01

We consider a spin-1/2 impurity interacting with conduction electrons in two different orbital channels via an isotropic spin exchange. The exchange is the same for both channels, but a crystalline field breaks the symmetry between the orbital channels. This corresponds to a splitting of the conduction electron Γ 8 into two doublets in the quadrupolar Kondo effect and to the application of an external magnetic field in the electron assisted tunneling of an atom in a double-well potential. We study the ground-state properties of the impurity as a function of the magnetic and crystalline fields. The crystalline field quenches the critical behavior of the overcompensated fixed point: The impurity ground state is a singlet. (orig.)

A one-dimensional plasma and impurity transport model for reversed field pinches

International Nuclear Information System (INIS)

Veerasingam, R.

1991-11-01

In this thesis a one-dimensional (1-D) plasma and impurity transport model is developed to address issues related to impurity behavior in Reversed Field Pinch (RFP) fusion plasmas. A coronal non-equilibrium model is used for impurities. The impurity model is incorporated into an existing one dimensional plasma transport model creating a multi-species plasma transport model which treats the plasma and impurity evolution self-consistently. Neutral deuterium particles are treated using a one-dimensional (slab) model of neutral transport. The resulting mode, RFPBI, is then applied to existing RFP devices such as ZT-40M and MST, and also to examine steady state behavior of ZTH based on the design parameters. A parallel algorithm for the impurity transport equations is implemented and tested to determine speedup and efficiency

Computers in the investigation of the impurity content of high-purity materials

International Nuclear Information System (INIS)

Makarov, Yu.B.; Yan'kov, S.V.

1987-01-01

The efficiency of the concept of data banks for the accumulation and processing of information is now generally acknowledged. In scientific investigations not only bibliographic but also factual data banks are becoming more and more prevalent. In this article, the authors consider the possibilities of providing a data bank on high-purity materials for the study of impurity contents. Also in this paper, the authors distinguish the following groups of problems that arise in the study of impurity composition and presents examples of their proposed solutions to these problems: the analysis of error and the determination of the most probably value of impurity concentration; the estimation of average properties of impurity composition with respect to groups of impurities and samples, and the forecast of the complete impurity composition

Impurity binding energy for δ-doped quantum well structures

Indian Academy of Sciences (India)

Administrator

Calculations are made for the case of not so big impurity concentrations, when impurity bands are not .... Blom et al (2003), but our data correspond qualitatively to Bastard's .... 0113U000612 and by Ukrainian Ministry of Education and Science ...

Summary of IAEA technical committee meeting on impurity control

International Nuclear Information System (INIS)

Itoh, Kimitaka.

1989-03-01

Presentations given in the IAEA technical committee meeting on impurity control (held in JAERI from 13 to 15 February, 1989) are summarized, putting the emphasis on the physics modelling of the plasma related to the impurity production and confinement. (author)

Purification of simple substances by distillation with impurity hydrothermal oxidation

International Nuclear Information System (INIS)

Kalashnik, O.N.; Nisel'son, L.A.

1987-01-01

A possibility of applying distillation method in water vapours for purification of simple substances from impurities is studied. Based on thermodynamic analysis of interaction processes in E-H 2 O system, conducted using a computer, it is as certained that SS, Se, Te, As, Cd, Hg can be purified from the majority of the impurities analysed by distillation in a water vapour flow. Behaviour of Zn, C, Ge, Al, Sb characteristic impurities under cadmium, arsenic and tellurium distillation is studied. Experiments on cadmium, arsenic and tellurium purification have confirmed, that distillation with hydrothermal oxidation of Zn, C, Ge impurities sometimes appears to be a more effective method as compared to distillation in a hydrogen flow

The effect of impurities on the electronic properties of MgO

Energy Technology Data Exchange (ETDEWEB)

Jalili, Seifollah [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of); Computational Physical Sciences Research Laboratory, Department of Nano-Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)], E-mail: sjalili@nano.ipm.ac.ir; Majidi, Roya [Department of Physics, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

2008-10-01

The effect of impurities on the electronic properties of MgO is investigated using the full potential linearized augmented plane-wave plus local-orbitals method based on density functional theory. The electronic band structures and density of states of MgO in the presence of Ca, Li, and Na impurities were calculated. It is found that increasing the amount of Ca impurity decreases the energy band gap and increases the width of the upper part of the valence band. Some of the considered impurities (Li and Na) change the electronic properties of MgO extensively.

The effect of impurities on the electronic properties of MgO

International Nuclear Information System (INIS)

Jalili, Seifollah; Majidi, Roya

2008-01-01

The effect of impurities on the electronic properties of MgO is investigated using the full potential linearized augmented plane-wave plus local-orbitals method based on density functional theory. The electronic band structures and density of states of MgO in the presence of Ca, Li, and Na impurities were calculated. It is found that increasing the amount of Ca impurity decreases the energy band gap and increases the width of the upper part of the valence band. Some of the considered impurities (Li and Na) change the electronic properties of MgO extensively

Impurity sublattice localization in ZnO revealed by li marker diffusion

DEFF Research Database (Denmark)

Azarov, A.Yu.; Knutsen, K.E.; Neuvonen, P.T.

2013-01-01

Sublattice localization of impurities in compound semiconductors, e.g., ZnO, determines their electronic and optical action. Despite that the impurity position may be envisaged based on charge considerations, the actual localization is often unknown, limiting our understanding of the incorporation...... and possible doping mechanisms. In this study, we demonstrate that the preferential sublattice occupation for a number of impurities in ZnO can be revealed by monitoring Li diffusion. In particular, using ion implantation, the impurity incorporation into the Zn sublattice (holds for, B, Mg, P, Ag, Cd, and Sb...

Device for separating, purifying and recovering nuclear fuel material, impurities and materials from impurity-containing nuclear fuel materials or nuclear fuel containing material

International Nuclear Information System (INIS)

Sato, Ryuichi; Kamei, Yoshinobu; Watanabe, Tsuneo; Tanaka, Shigeru.

1988-01-01

Purpose: To separate, purify and recover nuclear fuel materials, impurities and materials with no formation of liquid wastes. Constitution: Oxidizing atmosphere gases are introduced from both ends of a heating furnace. Vessels containing impurity-containing nuclear fuel substances or nuclear fuel substance-containing material are continuously disposed movably from one end to the other of the heating furnace. Then, impurity oxides or material oxides selectively evaporated from the impurity-containing nuclear fuel substances or nuclear fuel substance-containing materials are entrained in the oxidizing atmosphere gas and the gases are led out externally from a discharge port opened at the intermediate portion of the heating furnace, filters are disposed to the exit to solidify and capture the nuclear fuel substances and traps are disposed behind the filters to solidify and capture the oxides by spontaneous air cooling or water cooling. (Sekiya, K.)

Helium impurities in a PNP-primary coolant circuit

International Nuclear Information System (INIS)

Reif, M.

1981-01-01

The concentration of impurities to be expected have been defined in consideration of recent findings concerning the rates of infiltration and formation and the reaction mechanisms of the impurity components in the circuit. The data obtained correspond with the requirements on the metallic high-temperature components as well as with the requirements of limited graphite corrosion. (DG) [de

Density Imaging of Puy de Dôme Volcano by Joint Inversion of Muographic and Gravimetric Data

Science.gov (United States)

Barnoud, A.; Niess, V.; Le Ménédeu, E.; Cayol, V.; Carloganu, C.

2016-12-01

We aim at jointly inverting high density muographic and gravimetric data to robustly infer the density structure of volcanoes. We use the puy de Dôme volcano in France as a proof of principle since high quality data sets are available for both muography and gravimetry. Gravimetric inversion and muography are independent methods that provide an estimation of density distributions. On the one hand, gravimetry allows to reconstruct 3D density variations by inversion. This process is well known to be ill-posed and intrinsically non unique, thus it requires additional constraints (eg. a priori density model). On the other hand, muography provides a direct measurement of 2D mean densities (radiographic images) from the detection of high energy atmospheric muons crossing the volcanic edifice. 3D density distributions can be computed from several radiographic images, but the number of images is generally limited by field constraints and by the limited number of available telescopes. Thus, muon tomography is also ill-posed in practice.In the case of the puy de Dôme volcano, the density structures inferred from gravimetric data (Portal et al. 2016) and from muographic data (Le Ménédeu et al. 2016) show a qualitative agreement but cannot be compared quantitatively. Because each method has different intrinsic resolutions due to the physics (Jourde et al., 2015), the joint inversion is expected to improve the robustness of the inversion. Such joint inversion has already been applied in a volcanic context (Nishiyama et al., 2013).Volcano muography requires state-of-art, high-resolution and large-scale muon detectors (Ambrosino et al., 2015). Instrumental uncertainties and systematic errors may constitute an important limitation for muography and should not be overlooked. For instance, low-energy muons are detected together with ballistic high-energy muons, decreasing the measured value of the mean density closed to the topography.Here, we jointly invert the gravimetric and

Determining factors for the presence of impurities in selectively collected biowaste.

Science.gov (United States)

Puig-Ventosa, Ignasi; Freire-González, Jaume; Jofra-Sora, Marta

2013-05-01

The presence of impurities in biodegradable waste (biowaste) causes problems with the management of waste, among which are additional costs derived from the need to improve pre-treatment of biowaste, loss of treatment capacity and the difficulty selling treated biowaste as compost owing to its low quality. When treated biowaste is used for soil conditioning it can also cause soil pollution. Understanding the reasons why impurities are in biowaste and the factors affecting the percentage of impurities present can be used to determine ways to minimise these negative effects. This article attempts to identify the main causes for the presence of impurities in biowaste. In order to do so, it carries out an empirical analysis of the level of impurities in biowaste from municipal waste collection in two steps. First, a bivariate analysis focuses on significant correlations between the presence of impurities and several variables. Second, the construction of an explanatory model based on the significant relations obtained in the first step, and on literature research, are used to check the stated hypothesis. The estimates demonstrate that the collection system, the global levels of separate collection, the urban density of the municipality and the requirement to use compostable bags may be the main drivers of impurity levels in biowaste.

Understanding of impurity behavior in SST-1 plasmas using visible spectroscopy

International Nuclear Information System (INIS)

Manchanda, Ranjana; Ramaiya, Nilam; Chowdhuri, Malay Bikas; Banerjee, Santanu; Ghosh, Joydeep

2015-01-01

Studies of impurity behavior in SST-1 plasma have been carried out using visible spectroscopic systems installed on the tokomak. This has been carried out using a low resolution and broadband survey spectrometer covering a 350-900 nm wavelength range, 0.5 m visible spectrometer having 600 and 1200 grooves/mm grating coupled with CCD camera and interference filter and photomultiplier (PMT) tube based systems. Temporal evolution of the hydrogen (H α , H β ) and impurities emissions like, C II, C III, O I, O II, O III, O V and a visible Continuum at 536.0 nm have been monitored using the PMT based system to understand impurity charge state evolution during plasma discharges. All systems are absolutely calibrated for impurity influx and plasma parameter estimations. Observed spectral lines in the visible range have been identified to recognize the presence of various impurities in the SST-1 plasmas. Comparison of impurities emission has been made for different plasma currents and toroidal magnetic fields. An analysis has been carried out to understand the impurities activities in plasmas of SST-1 tokomak in presence and absence of installed plasma facing components (PFC). Significantly higher carbon emissions have been observed indicating higher carbon content in the plasma with graphite PFCs installed. (author)

Determination of uranium by a gravimetric-volumetric titration method

International Nuclear Information System (INIS)

Krtil, J.

1998-01-01

A volumetric-gravimetric modification of a method for the determination of uranium based on the reduction of uranium to U (IV) in a phosphoric acid medium and titration with a standard potassium dichromate solution is described. More than 99% of the stoichiometric amount of the titrating solution is weighed and the remainder is added volumetrically by using the Mettler DL 40 RC Memotitrator. Computer interconnected with analytical balances collects continually the data on the analyzed samples and evaluates the results of determination. The method allows to determine uranium in samples of uranium metal, alloys, oxides, and ammonium diuranate by using aliquot portions containing 30 - 100 mg of uranium with the error of determination, expressed as the relative standard deviation, of 0.02 - 0.05%. (author)

Quasiparticle Properties of a Mobile Impurity in a Bose-Einstein Condensate.

Science.gov (United States)

Christensen, Rasmus Søgaard; Levinsen, Jesper; Bruun, Georg M

2015-10-16

We develop a systematic perturbation theory for the quasiparticle properties of a single impurity immersed in a Bose-Einstein condensate. Analytical results are derived for the impurity energy, effective mass, and residue to third order in the impurity-boson scattering length. The energy is shown to depend logarithmically on the scattering length to third order, whereas the residue and the effective mass are given by analytical power series. When the boson-boson scattering length equals the boson-impurity scattering length, the energy has the same structure as that of a weakly interacting Bose gas, including terms of the Lee-Huang-Yang and fourth order logarithmic form. Our results, which cannot be obtained within the canonical Fröhlich model of an impurity interacting with phonons, provide valuable benchmarks for many-body theories and for experiments.

Gravimetric Analysis of Bismuth in Bismuth Subsalicylate Tablets: A Versatile Quantitative Experiment for Undergraduate Laboratories

Science.gov (United States)

Davis, Eric; Cheung, Ken; Pauls, Steve; Dick, Jonathan; Roth, Elijah; Zalewski, Nicole; Veldhuizen, Christopher; Coeler, Joel

2015-01-01

In this laboratory experiment, lower- and upper-division students dissolved bismuth subsalicylate tablets in acid and precipitated the resultant Bi[superscript 3+] in solution with sodium phosphate for a gravimetric determination of bismuth subsalicylate in the tablets. With a labeled concentration of 262 mg/tablet, the combined data from three…

Parametric dependences of impurity transport in the Tore Supra tokamak

International Nuclear Information System (INIS)

Parisot, Th.

2007-09-01

During this Ph.D. work, a full setup of tools for an experimental investigation of impurity transport has been developed on the Tore Supra tokamak. It includes a laser blow-off system for metallic impurity injections and developments for ITC (Impurity Transport Code), a transport code which allows the extraction of the experimental impurity transport coefficients (diffusion and convection velocity). This tool has been used to perform and analyse several experiments, to evidence parametric dependences of impurity transport. In a first experiment, a confinement time law for nickel in Tore Supra has been obtained as a function of collisionality ν * and normalized Larmor radius ρ * . Then the impurity charge Z role has been investigated in various conditions: ohmic regime with or without sawteeth, and sawtooth less L-mode with LH power. No Z effect is observed, consistently with theoretical predictions, whether neoclassical (NCLASS) or for turbulent transport with both non linear gyro-fluid (TRB) and quasilinear gyrokinetic (QuaLiKiz) simulations. An exception is found for LH heated plasmas where the confinement time seems to decrease for the heaviest impurities. This is not explained by any model available. The observed transport is close to neoclassical between sawtooth relaxations, in the centre (r q-1 ) of ohmic plasmas, turbulent outside. Without sawteeth, it is turbulent in the whole plasma, for ohmic or L mode discharges. The profile shape of the diffusion coefficient is here qualitatively different, with a stronger and deeper transition between the low diffusion central region and a more turbulent peripheral region for LH heated plasmas. (author)

Organic impurity profiling of 3,4-methylenedioxymethamphetamine (MDMA) synthesised from catechol.

Science.gov (United States)

Heather, Erin; Shimmon, Ronald; McDonagh, Andrew M

2015-03-01

This work examines the organic impurity profile of 3,4-methylenedioxymethamphetamine (MDMA) that has been synthesised from catechol (1,2-dihydroxybenzene), a common chemical reagent available in industrial quantities. The synthesis of MDMA from catechol proceeded via the common MDMA precursor safrole. Methylenation of catechol yielded 1,3-benzodioxole, which was brominated and then reacted with magnesium allyl bromide to form safrole. Eight organic impurities were identified in the synthetic safrole. Safrole was then converted to 3,4-methylenedioxyphenyl-2-propanone (MDP2P) using two synthetic methods: Wacker oxidation (Route 1) and an isomerisation/peracid oxidation/acid dehydration method (Route 2). MDMA was then synthesised by reductive amination of MDP2P. Thirteen organic impurities were identified in MDMA synthesised via Route 1 and eleven organic impurities were identified in MDMA synthesised via Route 2. Overall, organic impurities in MDMA prepared from catechol indicated that synthetic safrole was used in the synthesis. The impurities also indicated which of the two synthetic routes was utilised. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Classical confinement and outward convection of impurity ions in the MST RFP

Energy Technology Data Exchange (ETDEWEB)

Kumar, S. T. A.; Den Hartog, D. J.; Mirnov, V. V.; Eilerman, S.; Nornberg, M.; Reusch, J. A.; Sarff, J. S. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Caspary, K. J.; Chapman, B. E.; Parke, E. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Magee, R. M. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Brower, D. L.; Ding, W. X.; Lin, L. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States); Craig, D. [Physics Department, Wheaton College, Wheaton, Illinois 60187 (United States); Fiksel, G. [Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Laboratory for Laser Energetics, University of Rochester, Rochester, New York (United States)

2012-05-15

Impurity ion dynamics measured with simultaneously high spatial and temporal resolution reveal classical ion transport in the reversed-field pinch. The boron, carbon, oxygen, and aluminum impurity ion density profiles are obtained in the Madison Symmetric Torus [R. N. Dexter et al., Fusion Technol. 19, 131 (1991)] using a fast, active charge-exchange-recombination-spectroscopy diagnostic. Measurements are made during improved-confinement plasmas obtained using inductive control of tearing instability to mitigate stochastic transport. At the onset of the transition to improved confinement, the impurity ion density profile becomes hollow, with a slow decay in the core region concurrent with an increase in the outer region, implying an outward convection of impurities. Impurity transport from Coulomb collisions in the reversed-field pinch is classical for all collisionality regimes, and analysis shows that the observed hollow profile and outward convection can be explained by the classical temperature screening mechanism. The profile agrees well with classical expectations. Experiments performed with impurity pellet injection provide further evidence for classical impurity ion confinement.

Spectroscopic impurity survey in Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Buttenschoen, Birger; Burhenn, Rainer; Thomsen, Henning [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); Biel, Wolfgang; Assmann, Jochen; Hollfeld, Klaus-Peter [Forschungszentrum Juelich GmbH, Juelich (Germany); Collaboration: the Wendelstein 7-X Team

2016-07-01

The High Efficiency eXtreme ultraviolet Overview Spectrometer (HEXOS) has been developed specifically for impurity identification and survey purposes on the Wendelstein 7-X stellarator. This spectrometer system, consisting of four individual spectrometers, covers the wavelength range between λ=2.5 nm and λ=160 nm, observing the intense resonance lines of relevant Mg-, Na-, Be- and Li-like impurity ions as well as the high-Z W/Ta quasi-continua. During the first operation phase of W7-X, commissioning of HEXOS was finished by providing an in-situ wavelength calibration. The permanently acquired spectra are evaluated to monitor the overall impurity content in the plasma, and serve as an indicator for unintended plasma-wall contact possibly leading to machine damage. HEXOS results from the first operation phase of W7-X are presented and discussed with respect to future scientific exploitation of the available data.

Influence of impurities on the surface morphology of the TIBr crystal semiconductor

International Nuclear Information System (INIS)

Santos, Robinson A. dos; Silva, Julio B. Rodrigues da; Martins, Joao F.T.; Ferraz, Caue de M.; Costa, Fabio E. da; Mesquita, Carlos H. de; Hamada, Margarida M.; Gennari, Roseli F.

2013-01-01

The impurity effect in the surface morphology quality of TlBr crystals was evaluated, aiming a future application of these crystals as room temperature radiation semiconductor detectors. The crystals were purified and grown by the Repeated Bridgman technique. Systematic measurements were carried out for determining the stoichiometry, structure orientation, surface morphology and impurity of the crystal. A significant difference in the crystals impurity concentration was observed for almost all impurities, compared to those found in the raw material. The crystals wafer grown twice showed a surface roughness and grains which may be due to the presence of impurities on the surface, while those obtained with crystals grown three times presented a more uniform surface: even though, a smaller roughness was still observed. It was demonstrated that the impurities affect strongly the surface morphology quality of crystals. (author)

Stacking change in MoS2 bilayers induced by interstitial Mo impurities.

Science.gov (United States)

Cortés, Natalia; Rosales, Luis; Orellana, Pedro A; Ayuela, Andrés; González, Jhon W

2018-02-01

We use a theoretical approach to reveal the electronic and structural properties of molybdenum impurities between MoS 2 bilayers. We find that interstitial Mo impurities are able to reverse the well-known stability order of the pristine bilayer, because the most stable form of stacking changes from AA' (undoped) into AB' (doped). The occurrence of Mo impurities in different positions shows their split electronic levels in the energy gap, following octahedral and tetrahedral crystal fields. The energy stability is related to the accommodation of Mo impurities compacted in hollow sites between layers. Other less stable configurations for Mo dopants have larger interlayer distances and band gaps than those for the most stable stacking. Our findings suggest possible applications such as exciton trapping in layers around impurities, and the control of bilayer stacking by Mo impurities in the growth process.

Phase transition in one Josephson junction with a side-coupled magnetic impurity

Science.gov (United States)

Zhi, Li-Ming; Wang, Xiao-Qi; Jiang, Cui; Yi, Guang-Yu; Gong, Wei-Jiang

2018-04-01

This work focuses on one Josephson junction with a side-coupled magnetic impurity. And then, the Josephson phase transition is theoretically investigated, with the help of the exact diagonalization approach. It is found that even in the absence of intradot Coulomb interaction, the magnetic impurity can efficiently induce the phenomenon of Josephson phase transition, which is tightly related to the spin correlation manners (i.e., ferromagnetic or antiferromagnetic) between the impurity and the junction. Moreover, the impurity plays different roles when it couples to the dot and superconductor, respectively. This work can be helpful in describing the influence of one magnetic impurity on the supercurrent through the Josephson junction.

The influence of optical parameters on impurity determinations by IR spectroscopy

International Nuclear Information System (INIS)

Lombard, O.J.

1985-01-01

The important role of impurities in semiconductor materials is the subject of continuous research. The concentration of interstitial oxygen impurities in silicon are determined with the aid of infrared spectroscopy. The maximum absorption coefficient of the oxygen absorption peak, centered at 9,06 μm, is determined and the impurity concentration is then calculated using a calibration factor. This procedure was evaluated, paying particular attention to those optical parameters which may influence these impurity determinations. A thorough discussion of the theoretical and experimental aspects of infrared spectroscopy in general is followed by an overview of previous experimental work. This lead to some theoretical analysis regarding the influence of the index of refraction, the index of absorption and multiple reflections in the silicon wafer on impurity determinations. This lead to specific experimental investigations. The influence of the surface morphology of samples on impurity determinations was studied by determining the reflectance of silicon surfaces. It was established that the surface reflectance plays a role and that it must be taken into consideration for accurate impurity concentration determinations. The most accurate values for the absorption coefficient due to oxygen in silicon are calculated. This requires that the surface of the silicon wafers must be highly polished for the formula to be valid. Acceptable values for the absorption coefficient of damaged surfaces are obtained if the uncorrected formula is used. Experimental results may deviate as much as 32% from the real impurity concentration if the wrong formula is used to calculate the absorption coefficient of oxygen in silicon at 9,06 μm

On the radiative effects of light-absorbing impurities on snowpack evolution

Science.gov (United States)

Dumont, M.; Tuzet, F.; Lafaysse, M.; Arnaud, L.; Picard, G.; Lejeune, Y.; Lamare, M.; Morin, S.; Voisin, D.; Di Mauro, B.

2017-12-01

The presence of light absorbing impurities in snow strongly decreases snow reflectance leading to an increase in the amount of solar energy absorbed by the snowpack. This effect is also known as impurities direct radiative effect. The change in the amount of energy absorbed by the snowpack modifies the temperature profile inside the snowpack and in turn snow metamorphism (impurities indirect radiative effects). In this work, we used the detailed snowpack model SURFEX/ISBA-Crocus with an explicit representation of snow light-absorbing impurities content (Tuzet et al., 2017) fed by medium-resolution ALADIN-Climate atmospheric model to represent dust and black carbon atmospheric deposition fluxes. The model is used at two sites: Col de Porte (medium elevation site in the French Alps) and Torgnon (high elevation site in the Italian Alps). The simulations are compared to in-situ observations and used to quantify the effects of light-absorbing impurities on snow melt rate and timing. The respective parts of the direct and indirect radiative effects of light-absorbing impurities in snow are also computed for the two sites, emphasizing the need to account for the interactions between snow metamorphism and LAI radiative properties, to accurately predict the effects of light-absorbing impurities in snow. Moreover, we describe how automated hyperspectral reflectance can be used to estimate effective impurities surface content in snow. Finally we demonstrate how these reflectances measurements either from in situ or satellite data can be used via an assimilation scheme to constrain snowpack ensemble simulations and better predict the snowpack state and evolution.

Steady-state organization of binary mixtures by active impurities

DEFF Research Database (Denmark)

Sabra, Mads Christian; Gilhøj, Henriette; Mouritsen, Ole G.

1998-01-01

The structural reorganization of a phase-separated binary mixture in the presence of an annealed dilution of active impurities is studied by computer-simulation techniques via a simple two-dimensional lattice-gas model. The impurities, each of which has two internal states with different affinity...

Identification of impurities in sodium and its purification

International Nuclear Information System (INIS)

Subbotin, B.I.; Voltchkov, L.G.; Kozlov, F.A.; Zagorulko, Yu.I.; Kuznetsov, E.K.

1976-01-01

The paper presents some investigation results on sodium technology. In particular, a description is given of a calculation method for evaluation of sodium-cover gas-impurities equilibrium compositions as well as experimental results on development of methods for sodium sampling, equipment for non-metallic impurities (oxygen, hydrogen, carbon) constant control in sodium. The investigation results on sodium purification with cold traps are presented

Spectroscopical studies of impurities in the belt pinch HECTOR

International Nuclear Information System (INIS)

Singethan, J.

1981-04-01

In this paper UV-line-intensity measurements of impurities are presented, which have been performed in the belt-pinch HECTOR. From the line-intensities impurity concentrations and information on the radiation losses is be obtained. At temperatures below 100 eV, the energy loss due to line emission of oxygen and carbon impurities is one of the most important electron energy loss mechanisms. Thus the measurement and calculation of the radiation losses is of particular relevance. Furthermore the electron temperature time dependence can be obtained by comparing the line intensity time dependence with the solution of the respective rate equations. (orig./HT) [de

Prevention of serious impurity penetration into water-steam circuits

International Nuclear Information System (INIS)

Burgmann, F.; Bursik, A.; Flunkert, F.; Nieder, R.

1977-01-01

In consequence of reports from several power Plants concerning heavy damages due to penetrations of impurities into the water-steam circuit, the VGB Sub-Committee 'Water Chemistry in Thermal Power Plants' has established a working group to check-up how serious impurity penetration can be avoided. The lecture describes possible danger points. Suitable technical arrangements for the avoidance of penetrations, and possibilities for monitoring will be discussed. Penetration of impurities cannot be avoided with absolute reliability, even when the recommended arrangements and usual monitoring are realized. Additional measures for the protection of water steam circuits will be suggested. (orig.) [de

Impurity effects on the magnetic ordering in chromium

International Nuclear Information System (INIS)

Fishman, R.S.

1992-05-01

It is well-known that impurities profoundly alter the magnetic properties of chromium. While vanadium impurities suppress the Neel temperature T N , manganese impurities enhanced T N substantially. As evidenced by neutron scattering experiments, doping with as little as 0.2% vanadium changes the transition from weakly first order to second order. Young and Sokoloff explained that the first-order transition in pure chromium is caused by a charge-density wave which is the second harmonic of the spin-density wave. By examining the subtle balance between the spin-density and charge- density wave terms in the mean-field free energy, we find that the first-order transition is destroyed when the vanadium concentration exceeds about 0.15%, in agreement with experiments

Impurity Effects in Electroplated-Copper Solder Joints

Directory of Open Access Journals (Sweden)

Hsuan Lee

2018-05-01

Full Text Available Copper (Cu electroplating is a mature technology, and has been extensively applied in microelectronic industry. With the development of advanced microelectronic packaging, Cu electroplating encounters new challenges for atomic deposition on a non-planar substrate and to deliver good throwing power and uniform deposit properties in a high-aspect-ratio trench. The use of organic additives plays an important role in modulating the atomic deposition to achieve successful metallic coverage and filling, which strongly relies on the adsorptive and chemical interactions among additives on the surface of growing film. However, the adsorptive characteristic of organic additives inevitably results in an incorporation of additive-derived impurities in the electroplated Cu film. The incorporation of high-level impurities originating from the use of polyethylene glycol (PEG and chlorine ions significantly affects the microstructural evolution of the electroplated Cu film, and the electroplated-Cu solder joints, leading to the formation of undesired voids at the joint interface. However, the addition of bis(3-sulfopropyl disulfide (SPS with a critical concentration suppresses the impurity incorporation and the void formation. In this article, relevant studies were reviewed, and the focus was placed on the effects of additive formula and plating parameters on the impurity incorporation in the electroplated Cu film, and the void formation in the solder joints.

Two-dimensional impurity transport calculations for a high recycling divertor

International Nuclear Information System (INIS)

Brooks, J.N.

1986-04-01

Two dimensional analysis of impurity transport in a high recycling divertor shows asymmetric particle fluxes to the divertor plate, low helium pumping efficiency, and high scrapeoff zone shielding for sputtered impurities

Comparison of Glaciological and Gravimetric Glacier Mass Balance Measurements of Taku and Lemon Creek Glaciers, Southeast Alaska

Science.gov (United States)

Vogler, K.; McNeil, C.; Bond, M.; Getraer, B.; Huxley-Reicher, B.; McNamara, G.; Reinhardt-Ertman, T.; Silverwood, J.; Kienholz, C.; Beedle, M. J.

2017-12-01

Glacier-wide annual mass balances (Ba) have been calculated for Taku (726 km2) and Lemon Creek glaciers (10.2 km2) since 1946 and 1953 respectively. These are the longest mass balance records in North America, and the only Ba time-series available for Southeast Alaska, making them particularly valuable for the global glacier mass balance monitoring network. We compared Ba time-series from Taku and Lemon Creek glaciers to Gravity Recovery and Climate Experiment (GRACE) mascon solutions (1352 and 1353) during the 2004-2015 period to assess how well these gravimetric solutions reflect individual glaciological records. Lemon Creek Glacier is a challenging candidate for this comparison because it is small compared to the 12,100 km2 GRACE mascon solutions. Taku Glacier is equally challenging because its mass balance is stable compared to the negative balances dominating its neighboring glaciers. Challenges notwithstanding, a high correlation between the glaciological and gravimetrically-derived Ba for Taku and Lemon Creek glaciers encourage future use of GRACE to measure glacier mass balance. Additionally, we employed high frequency ground penetrating radar (GPR) to measure the variability of accumulation around glaciological sites to assess uncertainty in our glaciological measurements, and the resulting impact to Ba. Finally, we synthesize this comparison of glaciological and gravimetric mass balance solutions with a discussion of potential sources of error in both methods and their combined utility for measuring regional glacier change during the 21st century.

The electronic structure of impurities in semiconductors

CERN Multimedia

Nylandsted larsen, A; Svane, A

2002-01-01

The electronic structure of isolated substitutional or interstitial impurities in group IV, IV-IV, and III-V compound semiconductors will be studied. Mössbauer spectroscopy will be used to investigate the incorporation of the implanted isotopes on the proper lattice sites. The data can be directly compared to theoretical calculations using the LMTO scheme. Deep level transient spectroscopy will be used to identify the band gap levels introduced by metallic impurities, mainly in Si~and~Si$ _{x}$Ge$_{1-x}$. \\\\ \\\\

40 CFR 159.179 - Metabolites, degradates, contaminants, and impurities.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Metabolites, degradates, contaminants.../Benefit Information § 159.179 Metabolites, degradates, contaminants, and impurities. (a) Metabolites and... degradation of less than 10 percent in a 30-day period. (b) Contaminants and impurities. The presence in any...

Effects of electronically neutral impurities on muonium in germanium

International Nuclear Information System (INIS)

Clawson, C.W.; Crowe, K.M.; Haller, E.E.; Rosenblum, S.S.; Brewer, J.H.

1983-04-01

Low-temperature measurements of muonium parameters in various germanium crystals have been performed. We have measured crystals with different levels of neutral impurities, with and without dislocations, and with different annealing histories. The most striking result is the apparent trapping of Mu by silicon impurities in germanium

Measurement of the pulse pileup correction for the HPGe gamma spectrometer

International Nuclear Information System (INIS)

Kulkarni, D.B.; Anuradha, R.; Joseph, Leena; Kulkarni, M.S.

2018-01-01

Radiation Standards Section (RSS), RSSD, has HPGe gamma spectrometry system maintained as a secondary standard for standardization of gamma emitting radionuclides. This system is also used to detect the impurities in the radioactivity samples supplied for the international inter-comparison exercises, so that the appropriate correction can be made for the standardized activity of principle radionuclide. The system is calibrated as per the recommended procedure (ANSI standard N42.14, 1999). As a part of this calibration, measurement of the pulse pile up correction was carried out in the energy range of 81 keV to 1408 keV. The measurement of pileup correction is very important for the standardization of sources having higher counting rates where the extent of the pileup effect is more and considerable deviation from the true counting rates was observed. For these sources the measured photo peak counting rate is less than true counting rate and needs to be corrected for pileup effect. The details of experiments are discussed in this paper

Impurities in Drug Products and Active Pharmaceutical Ingredients.

Science.gov (United States)

Kątny, M; Frankowski, M

2017-05-04

Analytical methods should be selective and fast. In modern times, scientists strive to meet the criteria of green chemistry, so they choose analytical procedures that are as short as possible and use the least toxic solvents. It is quite obvious that the products intended for human consumption should be characterized as completely as possible. The safety of a drug is dependent mainly on the impurities that it contains. High pressure liquid chromatography and ultra-high pressure liquid chromatography have been proposed as the main techniques for forced degradation and impurity profiling. The aim of this article was to characterize the relevant classification of drug impurities and to review the methods of impurities determination for atorvastatin (ATV) and duloxetine (DLX) (both in active pharmaceutical ingredients and in different dosage forms). These drugs have an impact on two systems of the human body: cardiac and nervous. Simple characteristics of ATV and DLX, their properties and specificity of action on the human body, are also included in this review. The analyzed pharmaceuticals-ATV (brand name Lipiron) and DLX (brand name Cymbalta)-were selected for this study based on annual rankings prepared by Information Medical Statistics.

High-frequency EPR of surface impurities on nanodiamond

Science.gov (United States)

Peng, Zaili; Stepanov, Viktor; Takahashi, Susumu

Diamond is a fascinating material, hosting nitrogen-vacancy (NV) defect centers with unique magnetic and optical properties. There have been many reports that suggest the existence of paramagnetic impurities near surface of various kinds of diamonds. Electron paramagnetic resonance (EPR) investigation of mechanically crushed nanodiamonds (NDs) as well as detonation NDs revealed g 2 like signals that are attributed to structural defects and dangling bonds near the diamond surface. In this presentation, we investigate paramagnetic impurities in various sizes of NDs using high-frequency (HF) continuous wave (cw) and pulsed EPR spectroscopy. Strong size dependence on the linewidth of HF cw EPR spectra reveals the existence of paramagnetic impurities in the vicinity of the diamond surface. We also study the size dependence of the spin-lattice and spin-spin relaxation times (T1 and T2) of single substitutional nitrogen defects in NDs Significant deviations from the temperature dependence of the phonon-assisted T1 process were observed in the ND samples, and were attributed to the contribution from the surface impurities. This work was supported by the Searle Scholars Program and the National Science Foundation (DMR-1508661 and CHE-1611134).

Self-consistent gyrokinetic modeling of neoclassical and turbulent impurity transport

Science.gov (United States)

Estève, D.; Sarazin, Y.; Garbet, X.; Grandgirard, V.; Breton, S.; Donnel, P.; Asahi, Y.; Bourdelle, C.; Dif-Pradalier, G.; Ehrlacher, C.; Emeriau, C.; Ghendrih, Ph.; Gillot, C.; Latu, G.; Passeron, C.

2018-03-01

Trace impurity transport is studied with the flux-driven gyrokinetic GYSELA code (Grandgirard et al 2016 Comput. Phys. Commun. 207 35). A reduced and linearized multi-species collision operator has been recently implemented, so that both neoclassical and turbulent transport channels can be treated self-consistently on an equal footing. In the Pfirsch-Schlüter regime that is probably relevant for tungsten, the standard expression for the neoclassical impurity flux is shown to be recovered from gyrokinetics with the employed collision operator. Purely neoclassical simulations of deuterium plasma with trace impurities of helium, carbon and tungsten lead to impurity diffusion coefficients, inward pinch velocities due to density peaking, and thermo-diffusion terms which quantitatively agree with neoclassical predictions and NEO simulations (Belli et al 2012 Plasma Phys. Control. Fusion 54 015015). The thermal screening factor appears to be less than predicted analytically in the Pfirsch-Schlüter regime, which can be detrimental to fusion performance. Finally, self-consistent nonlinear simulations have revealed that the tungsten impurity flux is not the sum of turbulent and neoclassical fluxes computed separately, as is usually assumed. The synergy partly results from the turbulence-driven in-out poloidal asymmetry of tungsten density. This result suggests the need for self-consistent simulations of impurity transport, i.e. including both turbulence and neoclassical physics, in view of quantitative predictions for ITER.

Impurities block the alpha to omega martensitic transformation in titanium.

Science.gov (United States)

Hennig, Richard G; Trinkle, Dallas R; Bouchet, Johann; Srinivasan, Srivilliputhur G; Albers, Robert C; Wilkins, John W

2005-02-01

Impurities control phase stability and phase transformations in natural and man-made materials, from shape-memory alloys to steel to planetary cores. Experiments and empirical databases are still central to tuning the impurity effects. What is missing is a broad theoretical underpinning. Consider, for example, the titanium martensitic transformations: diffusionless structural transformations proceeding near the speed of sound. Pure titanium transforms from ductile alpha to brittle omega at 9 GPa, creating serious technological problems for beta-stabilized titanium alloys. Impurities in the titanium alloys A-70 and Ti-6Al-4V (wt%) suppress the transformation up to at least 35 GPa, increasing their technological utility as lightweight materials in aerospace applications. These and other empirical discoveries in technological materials call for broad theoretical understanding. Impurities pose two theoretical challenges: the effect on the relative phase stability, and the energy barrier of the transformation. Ab initio methods calculate both changes due to impurities. We show that interstitial oxygen, nitrogen and carbon retard the transformation whereas substitutional aluminium and vanadium influence the transformation by changing the d-electron concentration. The resulting microscopic picture explains the suppression of the transformation in commercial A-70 and Ti-6Al-4V alloys. In general, the effect of impurities on relative energies and energy barriers is central to understanding structural phase transformations.

Gravimetric model of the Gastre trough, province of Chubut, Argentina; Modelo gravimetrico en la fosa de Gastre, provincia de Chubut, Argentina

Energy Technology Data Exchange (ETDEWEB)

Lince Klinger, F.; Nacif, S.; Martinez, M. P.; Gimenez, M. E.; Ruiz, F.; Alvarez, O.

2011-07-01

A gravimetric study of the Gastre trough in the Province of Chubut, to the southwest of the Canadon Asfalto basin, has allowed us to determine the geometry of its crystalline basement. Using filtering techniques we were able to map residual Bouguer anomalies, which show the heterogeneities situated within the upper crust, some of which are linked to recognised geological structures. The gravimetric minima in the residual Bouguer anomaly map are associated with graben-type basins, flanked by positive gravity values associated with alignments identified on the surface and with the overall topographic relief of the Gastre trough. After suitable treatment of the density values of the outcrops and seismic data we were able to construct a 2D density model, perpendicular to the trough, which indicated a depth of 3600 m. The importance of this study lies in the fact that it has been possible to arrive at a gravimetric characterization of the Gastre trough in the Canadon Asfalto basin sector, a potentially hydrocarbon-bearing area hitherto lacking in reliable data concerning its subsoil. (Author)

Influence of impurities on silicide contact formation

International Nuclear Information System (INIS)

Kazdaev, Kh.R.; Meermanov, G.B.; Kazdaev, R.Kh.

2002-01-01

Research objectives of this work are to investigate the influence of light impurities implantation on peculiarities of the silicides formation in molybdenum monocrystal implanted by silicon, and in molybdenum films sputtered on silicon substrate at subsequent annealing. Implantation of the molybdenum samples was performed with silicon ions (90 keV, 5x10 17 cm -2 ). Phase identification was performed by X ray analysis with photographic method of registration. Analysis of the results has shown the formation of the molybdenum silicide Mo 3 Si at 900 deg. C. To find out the influence of impurities present in the atmosphere (C,N,O) on investigated processes we have applied combined implantation. At first, molybdenum was implanted with ions of the basic component (silicon) and then -- with impurities ions. Acceleration energies (40keV for C, 45 keV for N and 50 keV for O) were chosen to obtain the same distribution profiles for basic and impurities ions. Ion doses were 5x10 17 cm -2 for Si-ions and 5x10 16 cm -2 - for impurities. The most important results are reported here. The first, for all three kinds of impurities the decreased formation temperatures of the phase Mo 3 Si were observed; in the case of C and N it was ∼100 deg. and in the case of nitrogen - ∼200 deg. Further, simultaneously with the Mo 3 Si phase, the appearance of the rich-metal phase Mo 5 Si 3 was registered (not observed in the samples without additional implantation). In case of Mo/Si-structure, the implantation of the impurities (N,O) was performed to create the peak concentration (∼4at/%) located in the middle of the molybdenum film (∼ 150nm) deposited on silicon substrate. Investigation carried out on unimplanted samples showed the formation of the silicide molybdenum MoSi 2 , observed after annealing at temperatures 900/1000 deg. C, higher than values 500-600 deg. C reported in other works. It is discovered that electrical conductivity of Mo 5 Si 3 -films synthesized after impurities

Defect-impurity interactions in irradiated germanium

International Nuclear Information System (INIS)

Cleland, J.W.; James, F.J.; Westbrook, R.D.

1975-07-01

Results of experiments are used to formulate a better model for the structures of lattice defects and defect-impurity complexes in irradiated n-type Ge. Single crystals were grown by the Czochralski process from P, As, or Sb-doped melts, and less than or equal to 10 15 to greater than or equal to 10 17 oxygen cm -3 was added to the furnace chamber after approximately 1 / 3 of the crystal had been solidified. Hall coefficient and resistivity measurements (at 77 0 K) were used to determine the initial donor concentration due to the dopant and clustered oxygen, and infrared absorption measurements (at 11.7 μ) were used to determine the dissociated oxygen concentration. Certain impurity and defect-impurity interactions were then investigated that occurred as a consequence of selected annealing, quenching, Li diffusion, and irradiation experiments at approximately 300 0 K with 60 Co photons, 1.5 to 2.0 MeV electrons, or thermal energy neutrons. Particular attention was given to determining the electrical role of the irradiation produced interstitial and vacancy, and to look for any evidence from electrical and optical measurements of vacancy--oxygen, lithium--oxygen, and lithium--vacancy interactions. (U.S.)

Gravimetric and conductometric studies of the sedimentation kinetics in aqueous dispersions of kaoline

International Nuclear Information System (INIS)

Bulavyin, L.A.; Khrapatij, S.V.; Koval'chuk, V.Yi.; Klepko, V.V.; Lebovka, M.Yi.

2006-01-01

Using gravimetric and conductometric methods, the sedimentation kinetics in aqueous suspensions of Alekseev kaoline has been studied for pH value range from 4 to 10. It has been found that pH increasing leads to the decreasing of mean radii of flocks linearly. We found that sedimentation kinetics for intermediate pH values can be described by scaling equations that crossover time defined transition from a gravitational mechanism of deposition to the diffusion one

Spectroscopic and electron-ion collision data for plasma impurities

International Nuclear Information System (INIS)

Faenov, A.; Marchand, R.; Tawara, H.; Vainshtein, L.; Wiese, W.

1992-01-01

This Working Group Report briefly reviews and summarizes the available spectroscopic and electron-ion collision data for plasma impurities. Included are lithium, neon, and argon, which, although they are not plasma impurities per se, are introduced into the plasma through the application of diagnostic techniques. 32 refs, 2 tabs

Surface and subsurface continuous gravimetric monitoring of groundwater recharge processes through the karst vadose zone at Rochefort Cave (Belgium)

Science.gov (United States)

Watlet, A.; Van Camp, M. J.; Francis, O.; Poulain, A.; Hallet, V.; Triantafyllou, A.; Delforge, D.; Quinif, Y.; Van Ruymbeke, M.; Kaufmann, O.

2017-12-01

Ground-based gravimetry is a non-invasive and integrated tool to characterize hydrological processes in complex environments such as karsts or volcanoes. A problem in ground-based gravity measurements however concerns the lack of sensitivity in the first meters below the topographical surface, added to limited infiltration below the gravimeter building (umbrella effect). Such limitations disappear when measuring underground. Coupling surface and subsurface gravity measurements therefore allow isolating hydrological signals occurring in the zone between the two gravimeters. We present a coupled surface/subsurface continuous gravimetric monitoring of 2 years at the Rochefort Cave Laboratory (Belgium). The gravity record includes surface measurements of a GWR superconducting gravimeter and subsurface measurements of a Micro-g LaCoste gPhone gravimeter, installed in a cave 35 m below the surface station. The recharge of karstic aquifers is extremely complex to model, mostly because karst hydrological systems are composed of strongly heterogeneous flows. Most of the problem comes from the inadequacy of conventional measuring tools to correctly sample such heterogeneous media, and particularly the existence of a duality of flow types infiltrating the vadose zone: from rapid flows via open conduits to slow seepage through porous matrix. Using the surface/subsurface gravity difference, we were able to identify a significant seasonal groundwater recharge within the karst vadose zone. Seasonal or perennial perched reservoirs have already been proven to exist in several karst areas due to the heterogeneity of the porosity and permeability gradient in karstified carbonated rocks. Our gravimetric experiment allows assessing more precisely the recharge processes of such reservoirs. The gravity variations were also compared with surface and in-cave hydrogeological monitoring (i.e. soil moisture, in-cave percolating water discharges, water levels of the saturated zone). Combined

Gravimetric water distribution assessment from geoelectrical methods (ERT and EMI) in municipal solid waste landfill.

Science.gov (United States)

Dumont, Gaël; Pilawski, Tamara; Dzaomuho-Lenieregue, Phidias; Hiligsmann, Serge; Delvigne, Frank; Thonart, Philippe; Robert, Tanguy; Nguyen, Frédéric; Hermans, Thomas

2016-09-01

The gravimetric water content of the waste material is a key parameter in waste biodegradation. Previous studies suggest a correlation between changes in water content and modification of electrical resistivity. This study, based on field work in Mont-Saint-Guibert landfill (Belgium), aimed, on one hand, at characterizing the relationship between gravimetric water content and electrical resistivity and on the other hand, at assessing geoelectrical methods as tools to characterize the gravimetric water distribution in a landfill. Using excavated waste samples obtained after drilling, we investigated the influences of the temperature, the liquid phase conductivity, the compaction and the water content on the electrical resistivity. Our results demonstrate that Archie's law and Campbell's law accurately describe these relationships in municipal solid waste (MSW). Next, we conducted a geophysical survey in situ using two techniques: borehole electromagnetics (EM) and electrical resistivity tomography (ERT). First, in order to validate the use of EM, EM values obtained in situ were compared to electrical resistivity of excavated waste samples from corresponding depths. The petrophysical laws were used to account for the change of environmental parameters (temperature and compaction). A rather good correlation was obtained between direct measurement on waste samples and borehole electromagnetic data. Second, ERT and EM were used to acquire a spatial distribution of the electrical resistivity. Then, using the petrophysical laws, this information was used to estimate the water content distribution. In summary, our results demonstrate that geoelectrical methods represent a pertinent approach to characterize spatial distribution of water content in municipal landfills when properly interpreted using ground truth data. These methods might therefore prove to be valuable tools in waste biodegradation optimization projects. Copyright © 2016 Elsevier Ltd. All rights reserved.

Plasma impurity-control studies in CTX

International Nuclear Information System (INIS)

Barnes, C.W.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; Linford, R.K.; Marshall, J.; Sherwood, A.R.; Tuszewski, M.

1981-01-01

In the past, magnetized coaxial gun generated Compact Toroids (CTs) have exhibited magnetic field and density lifetimes of about 250 to 350 μs and electron temperatures of about 10 eV. In recent experiments, after hydrogen discharge cleaning the gun and flux conserver surfaces, the lifetimes have been extended to 550 μs. This improvement in lifetime, together with spectroscopic and bolometric measurements, are consistent with the interpretation that the CT plasma losses are impurity dominated and that discharge cleaning is reducing the impurities. Details of these measurements are described as well as successful experiments which led to a more open flux conserver

Plasma impurity-control studies in CTX

Energy Technology Data Exchange (ETDEWEB)

Barnes, C.W.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; Linford, R.K.; Marshall, J.; Sherwood, A.R.; Tuszewski, M.

1981-01-01

In the past, magnetized coaxial gun generated Compact Toroids (CTs) have exhibited magnetic field and density lifetimes of about 250 to 350 ..mu..s and electron temperatures of about 10 eV. In recent experiments, after hydrogen discharge cleaning the gun and flux conserver surfaces, the lifetimes have been extended to 550 ..mu..s. This improvement in lifetime, together with spectroscopic and bolometric measurements, are consistent with the interpretation that the CT plasma losses are impurity dominated and that discharge cleaning is reducing the impurities. Details of these measurements are described as well as successful experiments which led to a more open flux conserver.

Impurity penetration and transport during VH-mode on DIII-D

International Nuclear Information System (INIS)

Lippmann, S.I.; Evans, T.E.; Jackson, G.L.; West, W.P.

1992-05-01

A new modeling effort is made in order to understand the observed relatively low levels of impurity contamination during the VH-mode phase on DIII-D, as compared to those observed during the H-mode phase of selected discharges. The key element is the inclusion of the real 2-D flux surface geometry in the prediction of impurity penetration of sputtered atoms through the scrape-off layer into the core plasma. Of the elements which determine the impurity content in the plasma: sputtering yield, penetration, and core transport, the penetration through the scrape-off layer is found to be the most determinative factor. The low impurity content in VH-mode is attributed to the development of a scrape-off layer with higher density and temperature properties than those normally obtained in H-mode

Investigations on vertical crustal movements in the Venezuelan Andes by gravimetric methods

Science.gov (United States)

Drewes, H.

1978-01-01

A precise gravimetric network has been installed in the Venezuelan Andes to study eventual gravity changes due to vertical tectonic movements. The design and the measurements of the network are described and the accuracy is estimated. In the center of the region a local gravity network has been reobserved three times. The detected variations are discussed. In order to obtain a genuine statement as far as possible about the significance of observed gravity changes, requirements for the procedure of monitoring precise gravity networks are pointed out.

Application of InSAR and gravimetric surveys for developing construction codes in zones of land subsidence induced by groundwater extraction: case study of Aguascalientes, Mexico

Directory of Open Access Journals (Sweden)

J. Pacheco-Martínez

2015-11-01

Full Text Available Interferometric Synthetic Aperture Radar (InSAR has become a valuable tool for surface deformation monitoring, including land subsidence associated with groundwater extraction. Another useful tools for studying Earth's surface processes are geophysical methods such as Gravimetry. In this work we present the application of InSAR analysis and gravimetric surveying to generate valuable information for risk management related to land subsidence and surface faulting. Subsidence of the city of Aguascalientes, Mexico is presented as study case. Aguascalientes local governments have addressed land subsidence issues by including new requirements for new constructions projects in the State Urban Construction Code. Nevertheless, the resulting zoning proposed in the code is still subjective and not clearly defined. Our work based on gravimetric and InSAR surveys is aimed for improving the subsidence hazard zoning proposed in the State Urban Code in a more comprehensive way. The study includes a 2007–2011 ALOS InSAR time-series analysis of the Aguascalientes valley, an interpretation of the compete Bouguer gravimetric anomaly of the Aguascalientes urban area, and the application of time series and gravimetric anomaly maps for improve the subsidence hazard zoning of Aguascalientes City.

Studies of impurity recycling by the collector probe technique

International Nuclear Information System (INIS)

Hildebrandt, D.; Grote, H.; Herrmann, A.; Laux, M.; Pech, P.; Reiner, H.D.; Wolff, H.

1987-01-01

In order to study recycling effects of the nonintrinsic impurity Li discharges with and without LiD-pellet injection were investigated. The observed maximum impurity level of Li in the SOL plasma of discharges without injection reaches less than 10% of that observed in discharges with injection. The measurements offer the possibility to distinguish between influxes from the wall and those which reach the collector probe via the core plasma. The time evolution, orientation and radial dependence of the impurity fluxes are characteristic features of their origin. The consideration of all these features facilitates a better understanding of collector probe measurements in the SOL-plasma. (orig.)

Patterns induced by magnetic impurities in d-wave superconductors

International Nuclear Information System (INIS)

Zuo Xianjun; Gong Changde; Zhou Yuan

2010-01-01

We investigate the modulated patterns induced by magnetic impurities in d-wave superconductors (DSCs) near optimal doping based on the t-t ' -U-V model. Modulated checkerboard patterns with periodicity of eight or four lattice constants (8a or 4a) in the spin-, charge- and DSC orders are observed. Moreover, the checkerboard modulation in the spin order appear to be robust against parameter changes, which is consistent with neutron-scattering experiments. For the two-impurity case, a modulated stripe-like spin order with periodicity 8a is induced, which coexists with the DSC order. Further experiments of magnetic impurity substitution in DSCs are expected to check these results.

Patterns induced by magnetic impurities in d-wave superconductors

Science.gov (United States)

Zuo, Xian-Jun; Gong, Chang-De; Zhou, Yuan

2010-07-01

We investigate the modulated patterns induced by magnetic impurities in d-wave superconductors (DSCs) near optimal doping based on the t-t-U-V model. Modulated checkerboard patterns with periodicity of eight or four lattice constants (8 a or 4 a) in the spin-, charge- and DSC orders are observed. Moreover, the checkerboard modulation in the spin order appear to be robust against parameter changes, which is consistent with neutron-scattering experiments. For the two-impurity case, a modulated stripe-like spin order with periodicity 8 a is induced, which coexists with the DSC order. Further experiments of magnetic impurity substitution in DSCs are expected to check these results.

Nonlinear excitations in two-dimensional molecular structures with impurities

DEFF Research Database (Denmark)

Gaididei, Yuri Borisovich; Rasmussen, Kim; Christiansen, Peter Leth

1995-01-01

We study the nonlinear dynamics of electronic excitations interacting with acoustic phonons in two-dimensional molecular structures with impurities. We show that the problem is reduced to the nonlinear Schrodinger equation with a varying coefficient. The latter represents the influence...... of the impurity. Transforming the equation to the noninertial frame of reference coupled with the center of mass we investigate the soliton behavior in the close vicinity of the impurity. With the help of the lens transformation we show that the soliton width is governed by an Ermakov-Pinney equation. We also...... excitations. Analytical results are in good agreement with numerical simulations of the nonlinear Schrodinger equation....

Finite-temperature behavior of an impurity in the spin-1/2 XXZ chain

International Nuclear Information System (INIS)

Yahagi, Ryoko; Deguchi, Tetsuo; Sato, Jun

2014-01-01

We study the zero- and the finite-temperature behavior of the integrable spin-1/2 XXZ periodic chain with an impurity by the algebraic and thermal Bethe ansatz methods. We evaluate the local magnetization on the impurity site at zero temperature analytically and derive the impurity susceptibility exactly from it. In the graphs of the impurity specific heat versus temperature, we show how the impurity spin becomes more liberated from the bulk many-body effect as the exchange coupling between the impurity spin and other spins decreases and that at low temperature it couples strongly to them such as in the Kondo effect. Thus, we observe not only the crossover behavior from the high- to the low-temperature regime, but another from the N-site chain to the (N − 1)-site chain with a free impurity spin. We also show that the estimate of the Wilson ratio at a given low temperature is independent of the impurity parameter if its absolute value is small enough with respect to the temperature and the universality class is described by the XXZ anisotropy in terms of the dressed charge. (paper)

Nonlinearity and disorder: Classification and stability of nonlinear impurity modes

DEFF Research Database (Denmark)

Sukhorukov, Andrey A.; Kivshar, Yuri S.; Bang, Ole

2001-01-01

We study the effects produced by competition of two physical mechanisms of energy localization in inhomogeneous nonlinear systems. As an example, we analyze spatially localized modes supported by a nonlinear impurity in the generalized nonlinear Schrödinger equation and describe three types of no...... the case of a power-law nonlinearity in detail. We discuss several scenarios of the instability-induced dynamics of the nonlinear impurity modes, including the mode decay or switching to a new stable state, and collapse at the impurity site....

Detection, isolation and characterization of principle synthetic route indicative impurity in telmisartan

Directory of Open Access Journals (Sweden)

V. Srinivasan

2016-11-01

Full Text Available An unknown impurity was detected in the telmisartan bulk drug (active pharmaceutical ingredient – API using an isocratic reversed-phase high performance liquid chromatography (HPLC. This impurity was isolated by preparative HPLC. Spectral data of the isolated impurity were collected. Based on the spectral data deriving from two dimensional nuclear magnetic spectroscopy (2D-NMR and mass spectrometry (MS, the impurity was characterized as “methyl 4′,4′-dibromo methyl biphenyl-2-carboxylate”. The arrived structure was further confirmed by theoretical studies.

Pfirsch–Schlüter neoclassical heavy impurity transport in a rotating plasma

International Nuclear Information System (INIS)

Belli, E A; Candy, J; Angioni, C

2014-01-01

In this work, we extend previous analytic theories for the neoclassical transport of a trace heavy impurity in a rotating plasma in the Pfirsch–Schlüter regime. The complete diffusive and convective components of the ambipolar particle flux are derived. The solution is valid for arbitrary impurity charge and impurity Mach number and for general geometry. Inclusion of finite main-ion temperature gradient effects is shown in the small ion Mach number limit. A simple interpolation formula is derived for the case of high impurity charge and circular geometry. While an enhancement of the diffusion coefficient is found for order one impurity Mach number, a reduction due to the rotation-driven poloidal asymmetry in the density occurs for very large Mach number. (paper)

Extended numerical modeling of impurity neoclassical transport in tokamak edge plasmas

International Nuclear Information System (INIS)

Inoue, H.; Yamoto, S.; Hatayama, A.; Homma, Y.

2016-01-01

Understanding of impurity transport in tokamaks is an important issue in order to reduce the impurity contamination in fusion core plasmas. Recently, a new kinetic numerical scheme of impurity classical/neoclassical transport has been developed. This numerical scheme makes it possible to include classical self-diffusion (CL SD), classical inward pinch (CL IWP), and classical temperature screening effect (CL TSE) of impurity ions. However, impurity neoclassical transport has been modeled only in the case where background plasmas are in the Pfirsch-Schluter (PS) regime. The purpose of this study is to extend our previous model to wider range of collisionality regimes, i.e., not only the PS regime, but also the plateau regime. As in the previous study, a kinetic model with Binary Collision Monte-Carlo Model (BMC) has been adopted. We focus on the modeling of the neoclassical self-diffusion (NC SD) and the neoclassical inward pinch (NC IWP). In order to simulate the neoclassical transport with the BCM, velocity distribution of background plasma ions has been modeled as a deformed Maxwell distribution which includes plasma density gradient. Some test simulations have been done. As for NC SD of impurity ions, our scheme reproduces the dependence on the collisionality parameter in wide range of collisionality regime. As for NC IWP, in cases where test impurity ions and background ions are in the PS and plateau regimes, parameter dependences have been reproduced. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Extended numerical modeling of impurity neoclassical transport in tokamak edge plasmas

Energy Technology Data Exchange (ETDEWEB)

Inoue, H.; Yamoto, S.; Hatayama, A. [Graduate School of Science and Technology, Keio University, Hiyoshi, Yokohama (Japan); Homma, Y. [Graduate School of Science and Technology, Keio University, Hiyoshi, Yokohama (Japan); Research Fellow of Japan Society for the Promotion of Science, Tokyo (Japan)

2016-08-15

Understanding of impurity transport in tokamaks is an important issue in order to reduce the impurity contamination in fusion core plasmas. Recently, a new kinetic numerical scheme of impurity classical/neoclassical transport has been developed. This numerical scheme makes it possible to include classical self-diffusion (CL SD), classical inward pinch (CL IWP), and classical temperature screening effect (CL TSE) of impurity ions. However, impurity neoclassical transport has been modeled only in the case where background plasmas are in the Pfirsch-Schluter (PS) regime. The purpose of this study is to extend our previous model to wider range of collisionality regimes, i.e., not only the PS regime, but also the plateau regime. As in the previous study, a kinetic model with Binary Collision Monte-Carlo Model (BMC) has been adopted. We focus on the modeling of the neoclassical self-diffusion (NC SD) and the neoclassical inward pinch (NC IWP). In order to simulate the neoclassical transport with the BCM, velocity distribution of background plasma ions has been modeled as a deformed Maxwell distribution which includes plasma density gradient. Some test simulations have been done. As for NC SD of impurity ions, our scheme reproduces the dependence on the collisionality parameter in wide range of collisionality regime. As for NC IWP, in cases where test impurity ions and background ions are in the PS and plateau regimes, parameter dependences have been reproduced. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Electromagnetic effects on trace impurity transport in tokamak plasmas

Science.gov (United States)

Hein, T.; Angioni, C.

2010-01-01

The impact of electromagnetic effects on the transport of light and heavy impurities in tokamak plasmas is investigated by means of an extensive set of linear gyrokinetic numerical calculations with the code GYRO [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] and of analytical derivations with a fluid model. The impurity transport is studied by appropriately separating diffusive and convective contributions, and conditions of background microturbulence dominated by both ion temperature gradient (ITG) and trapped electron modes (TEMs) are analyzed. The dominant contribution from magnetic flutter transport turns out to be of pure convective type. However it remains small, below 10% with respect to the E ×B transport. A significant impact on the impurity transport due to an increase in the plasma normalized pressure parameter β is observed in the case of ITG modes, while for TEM the overall effect remains weak. In realistic conditions of high β plasmas in the high confinement (H-) mode with dominant ITG turbulence, the impurity diffusivity is found to decrease with increasing β in qualitative agreement with recent observations in tokamaks. In contrast, in these conditions, the ratio of the total off-diagonal convective velocity to the diagonal diffusivity is not strongly affected by an increase in β, particularly at low impurity charge, due to a compensation between the different off-diagonal contributions.

Three years of high precision gravity measurements at the gravimetric station of Brasimone - Italy

Directory of Open Access Journals (Sweden)

G. Casula

1998-06-01

Full Text Available From August 1995 up to now, at the Enea Research Center of Brasimone, in the Italian Apennines between Bologna and Florence (Italy: 44º07'N, 11º.07'E, 890 m height, the superconducting gravimeter GWR model TT70 number T015 has been continuously recording the variation of the local gravity field, in the frame of the Global Geodynamics Project. The gravimetric laboratory, being a room of the disused nuclear power plant of Brasimone, is a very stable site, free from noise due to human activities. Data blocks of several months of continuous gravity records have been collected over a time span of three years, together with the meteorological data. The gravimeter has been calibrated at relative accuracy better than 0.3% with the aid of a mobile mass system, by imposed perturbations of the local gravity field and recording the gravimeter response. The results of this calibration technique were checked by two comparison experiments with absolute gravimeters performed during this period: the first, in May 1994 with the aid of the symmetrical rise and fall gravimeter of the Institute of Metrology Colonnetti of Turin, and the second in October 1997 involving an FG5 absolute gravimeter of the Institute de Physique du Globe of Strasbourg. The gravimeter signal was analysed to compute a high precision tidal model for Brasimone site. Starting from a set of gravimetric and atmospheric pressure data of high quality, relative to 46 months of observation, we performed the tidal analysis using Eterna 3.2 software to compute amplitudes, gravimetric factors and phases of the main waves of the Tamura catalogue. Finally a comparison experiment between two of the STS-1/VBB broadband seismometers of the MedNet project network and the gravity records relative to the Balleny Islands earthquake (March 25, 1998 were analysed to look for evidence of normal modes due to the free oscillations of the Earth.

Nuclear relaxation in semiconductors doped with magnetic impurities

International Nuclear Information System (INIS)

Mel'nichuk, S.V.; Tovstyuk, N.K.

1984-01-01

The temperature and concentration dependences are investigated of the nuclear spin-lattice relaxation time with account of spin diffusion for degenerated and non-degenerated semicon- ductors doped with magnetic impurities. In case of the non-degenerated semiconductor the time is shown to grow with temperature, while in case of degenerated semiconductor it is practically independent of temperature. The impurity concentration growth results in decreasing the spin-lattice relaxation time

Gravimetric preparation and characterization of primary reference solutions of molybdenum and rhodium.

Science.gov (United States)

Kaltenbach, Angela; Noordmann, Janine; Görlitz, Volker; Pape, Carola; Richter, Silke; Kipphardt, Heinrich; Kopp, Gernot; Jährling, Reinhard; Rienitz, Olaf; Güttler, Bernd

2015-04-01

Gravimetrically prepared mono-elemental reference solutions having a well-known mass fraction of approximately 1 g/kg (or a mass concentration of 1 g/L) define the very basis of virtually all measurements in inorganic analysis. Serving as the starting materials of all standard/calibration solutions, they link virtually all measurements of inorganic analytes (regardless of the method applied) to the purity of the solid materials (high-purity metals or salts) they were prepared from. In case these solid materials are characterized comprehensively with respect to their purity, this link also establishes direct metrological traceability to The International System of Units (SI). This, in turn, ensures the comparability of all results on the highest level achievable. Several national metrology institutes (NMIs) and designated institutes (DIs) have been working for nearly two decades in close cooperation with commercial producers on making an increasing number of traceable reference solutions available. Besides the comprehensive characterization of the solid starting materials, dissolving them both loss-free and completely under strict gravimetric control is a challenging problem in the case of several elements like molybdenum and rhodium. Within the framework of the European Metrology Research Programme (EMRP), in the Joint Research Project (JRP) called SIB09 Primary standards for challenging elements, reference solutions of molybdenum and rhodium were prepared directly from the respective metals with a relative expanded uncertainty associated with the mass fraction of U rel(w) methods required to assist with the preparation and as dissemination tools.

Impurity band Mott insulators: a new route to high Tc superconductivity

Directory of Open Access Journals (Sweden)

Ganapathy Baskaran

2008-01-01

Full Text Available Last century witnessed the birth of semiconductor electronics and nanotechnology. The physics behind these revolutionary developments is certain quantum mechanical behaviour of 'impurity state electrons' in crystalline 'band insulators', such as Si, Ge, GaAs and GaN, arising from intentionally added (doped impurities. The present article proposes that certain collective quantum behaviour of these impurity state electrons, arising from Coulomb repulsions, could lead to superconductivity in a parent band insulator, in a way not suspected before. Impurity band resonating valence bond theory of superconductivity in boron doped diamond, recently proposed by us, suggests possibility of superconductivity emerging from impurity band Mott insulators. We use certain key ideas and insights from the field of high-temperature superconductivity in cuprates and organics. Our suggestion also offers new possibilities in the field of semiconductor electronics and nanotechnology. The current level of sophistication in solid state technology and combinatorial materials science is very well capable of realizing our proposal and discover new superconductors.

Edge and Core Impurity Transport Study with Spectroscopic Instruments in LHD

International Nuclear Information System (INIS)

Morita, Shigeru; Goto, Motoshi; Kobayashi, Masahiro; Muto, Sadatsugu; Chowdhuri, Malay Bikas; Chunfeng, Dong; Hangyu, Zhou; Zhengying, Cui; Fujii, Keisuke; Hasuo, Masahiro; Iwamae, Atsushi; Furuzawa, Akihiro; Sakurai, Ikuya; Tawara, Yuzuru; Yinxian, Jie; Baonian, Wan; Zhenwei, Wu; Koubiti, Mohammed; Yamaguchi, Naohiro

2009-01-01

Impurity transport was investigated at both edge and core regions in large helical device (LHD) with developed spectroscopic instruments which can measure one- and two-dimensional distributions of impurities. The edge impurity behavior was studied recently using four carbon resonant transitions in different ionization stages of CIII (977A), CIV (1548A), CV (40.3A) and CVI (33.7A). When the line-averaged electron density, n e , is increased from 1 to 6 x 10 13 cm -3 , the ratio of (CIII+CIV)/n e increases while the ratio of (CV+CVI)/n e decreases. Here, CIII+CIV (CV+CVI) expresses the sum of CIII (CV) and CIV (CVI) intensities. The CIII+CIV indicates the carbon influx and the CV+CVI indicates the emissions through the transport in the ergodic layer. The result thus gives experimental evidence on the impurity screening by the ergodic layer in LHD, which is also supported by a three-dimensional edge particle simulation. The core impurity behavior is also studied in high-density discharges (n e ≤ 1x 10 15 cm -3 ) with multi H 2 -pellets injection. It is found that the ratio of V/D (V: convection velocity, D: diffusion coefficient) decreases after pellet injection and Z eff profile shows a flat one at values of 1.1-1.2. These results confirm no impurity accumulation occurs in high-density discharges. As a result, the iron density, n Fe , is analyzed to be 6 x 10 -7 ( = n Fe /n e ) of which the amount can be negligible as radiation source even in such high-density discharges. One- and two-dimensional impurity distributions from space-resolved VUV and EUV spectrometers newly developed for further impurity transport study are also presented with their preliminary results. (magnetically confined plasma)

Modeling impurity-assisted chain creation in noble-metal break junctions

International Nuclear Information System (INIS)

Di Napoli, S; Thiess, A; Blügel, S; Mokrousov, Y

2012-01-01

In this work we present the generalization of the model for chain formation in break junctions, introduced by Thiess et al (2008 Nano Lett. 8 2144), to zigzag transition-metal chains with s and p impurities. We apply this extended model to study the producibility trends for noble-metal chains with impurities, often present in break junction experiments, namely, Cu, Ag and Au chains with H, C, O and N adatoms. Providing the material-specific parameters for our model from systematic full-potential linearized augmented plane-wave first-principles calculations, we find that the presence of such impurities crucially affects the binding properties of the noble-metal chains. We reveal that both the impurity-induced bond strengthening and the formation of zigzag bonds can lead to a significantly enhanced probability for chain formation in break junctions. (paper)

Corrosion behavior of pyroclore-rich titanate ceramics for plutonium disposition; impurity effects

International Nuclear Information System (INIS)

Bakel, A. J.

1999-01-01

The baseline ceramic contains Ti, U, Ca, Hf, Gd, and Ce, and is made up of only four phases, pyrochlore, zirconolite, rutile, and brannerite. The impurities present in the three other ceramics represent impurities expected in the feed, and result in different phase distributions. The results from 3 day, 90 C MCC-1 tests with impurity ceramics were significantly different than the results from tests with the baseline ceramic. Overall, the addition of impurities to these titanate ceramics alters the phase distributions, which in turn, affects the corrosion behavior

Impurity monitoring by laser-induced fluorescence techniques

International Nuclear Information System (INIS)

Gelbwachs, J.A.

1984-01-01

Laser-induced fluorescence spectroscopy can provide a highly sensitive and selective means of detecting atomic and ionic impurities. Because the photodetector can be physically isolated from the laser-excited region, these techniques can be applied to monitoring in hostile environments. The basic concepts behind fluorescence detection are reviewed. Saturated optical excitation is shown to maximize impurity atom emission yield while mitigating effects of laser intensity fluctuations upon absolute density calibration. Monitoring in high- and low-pressure monitoring environments is compared. Methods to improve detection sensitivity by luminescence background suppression are presented

Classical impurity ion confinement in a toroidal magnetized fusion plasma.

Science.gov (United States)

Kumar, S T A; Den Hartog, D J; Caspary, K J; Magee, R M; Mirnov, V V; Chapman, B E; Craig, D; Fiksel, G; Sarff, J S

2012-03-23

High-resolution measurements of impurity ion dynamics provide first-time evidence of classical ion confinement in a toroidal, magnetically confined plasma. The density profile evolution of fully stripped carbon is measured in MST reversed-field pinch plasmas with reduced magnetic turbulence to assess Coulomb-collisional transport without the neoclassical enhancement from particle drift effects. The impurity density profile evolves to a hollow shape, consistent with the temperature screening mechanism of classical transport. Corroborating methane pellet injection experiments expose the sensitivity of the impurity particle confinement time to the residual magnetic fluctuation amplitude.

First-principles thermodynamic calculations of diffusion characteristics of impurities in γ-iron

International Nuclear Information System (INIS)

Tsuru, T.; Kaji, Y.

2013-01-01

Because solute impurities have an effect on embrittlement through segregation under irradiation, solute stability and the influence of irradiation on the diffusion characteristics of impurities become prominent due to several acceleration effects of high irradiance circumstances in irradiated materials. In this study, the diffusion characteristics of several impurities in non-magnetic fcc iron are investigated using first-principles density functional theory (DFT) calculations. In accordance with classical diffusion and transition state theories, we nonempirically evaluated the contribution to properties of the binding energy between vacancy and each impurity and the migration enthalpy. The migration energy was calculated using the nudged elastic band method with DFT. The vacancy formation energy, including the entropic contributions to free energies in γ-iron, was evaluated by considering vibrational phonon frequencies based on frozen phonons employing the harmonic approximation for the lattice dynamics. Consequently, we confirmed that the binding energy between large-radius impurities and vacancies is larger than that with an equivalent size of the solvent element, and that the migration enthalpies of these impurities are quite small compared with self diffusion. This finding may indicate that the electronic binding states at the saddle point have a large influence on the migration of impurities

Determination of sulfate in thorium salts using gravimetric technique with previous thorium separation

International Nuclear Information System (INIS)

Silva, C.M. da; Pires, M.A.F.

1994-01-01

Available as short communication only. A simple analytical method to analyze sulfates in thorium salt, is presented. The method is based on the thorium separation as hydroxide. The gravimetric technique is used to analyze the sulfate in the filtered as barium sulfate. Using this method, the sulfate separation from thorium has been reach 99,9% yield, and 0,1% precision. This method is applied to thorium salts specifically thorium sulfate, carbonate and nitrate. (author). 5 refs, 2 tabs

Strongly correlated impurity band superconductivity in diamond: X-ray spectroscopic evidence

Directory of Open Access Journals (Sweden)

G. Baskaran

2006-01-01

Full Text Available In a recent X-ray absorption study in boron doped diamond, Nakamura et al. have seen a well isolated narrow boron impurity band in non-superconducting samples and an additional narrow band at the chemical potential in a superconducting sample. We interpret the beautiful spectra as evidence for upper Hubbard band of a Mott insulating impurity band and an additional metallic 'mid-gap band' of a conducting 'self-doped' Mott insulator. This supports the basic framework of a recent theory of the present author of strongly correlated impurity band superconductivity (impurity band resonating valence bond, IBRVB theory in a template of a wide-gap insulator, with no direct involvement of valence band states.

Hyperfine magnetic fields for 5d impurities in iron: pre-equilibrium effects, texture and the Aharoni effect

International Nuclear Information System (INIS)

Stuchbery, A.E.; Bezakova, E.

1998-01-01

Static magnetic hyperfine fields acting on impurities recoil-implanted into ferromagnetic hosts following heavy-ion induced reactions have been studied using the implantation perturbed angular correlation (IMPAC) technique to determine the magnetic moments of subnanosecond excited states in neutron-deficient nuclei. Problems, which in time-integral measurements cannot always be treated independently were studied and include: (i) corrections for the transient field effect, (ii) whether the hyperfine field is parallel to the applied field, (iii) whether the implanted nuclei all experience the same magnetic interaction, (iv) the time the static field takes to reach equilibrium after implantation. The focus here is on pre-equilibrium phenomena associated with the implantation process and the direction of the internal magnetic field at implanted impurities after equilibrium is reached. It was found that the internal field does become increasingly misaligned with respect to external field direction at fields below 0.08 T. This is due to the incomplete saturation of the foil and not to the microscopic effect as proposed by Aharoni

Comparison of gravimetric and gas chromatographic methods for assessing performance of textile materials against liquid pesticide penetration.

Science.gov (United States)

Shaw, Anugrah; Abbi, Ruchika

2004-01-01

Penetration of liquid pesticides through textile materials is a criterion for determining the performance of protective clothing used by pesticide handlers. The pipette method is frequently used to apply liquid pesticides onto textile materials to measure penetration. Typically, analytical techniques such as Gas Chromatography (GC) are used to measure percentage penetration. These techniques are labor intensive and costly. A simpler gravimetric method was developed, and tests were conducted to compare the gravimetric and GC methods of analysis. Three types of pesticide formulations and 4 fabrics were used for the study. Diluted pesticide formulations were pipetted onto the test specimens and percentage penetration was measured using the 2 methods. For homogeneous formulation, the results of the two methods were fairly comparable. However, due to the filtering action of the textile materials, there were differences in the percentage penetration between the 2 methods for formulations that were not homogeneous.

The effects of naturally occurring impurities in rock salt

Indian Academy of Sciences (India)

In this paper we investigate the effect that naturally occurring impurities in salt mines have both on effective permittivity of the medium and on radio wave propagation at ∼200 MHz. The effective permittivity is determined based on the dielectric properties of salt and the characteristics of the main impurities. We conclude that ...

Size, Shape and Impurity Effects on Superconducting critical temperature.

Science.gov (United States)

Umeda, Masaki; Kato, Masaru; Sato, Osamu

Bulk superconductors have their own critical temperatures Tc. However, for a nano-structured superconductor, Tc depends on size and shape of the superconductor. Nishizaki showed that the high pressure torsion on bulks of Nb makes Tc higher, because the torsion makes many nano-sized fine grains in the bulks. However the high pressure torsion on bulks of V makes Tc lower, and Nishizaki discussed that the decrease of Tc is caused by impurities in the bulks of V. We studied size, shape, and impurity effects on Tc, by solving the Gor'kov equations, using the finite element method. We found that smaller and narrower superconductors show higher Tc. We found how size and shape affects Tc by studying spacial order parameter distributions and quasi-particle eigen-energies. Also we studied the impurity effects on Tc, and found that Tc decreases with increase of scattering rate by impurities. This work was supported in part of KAKENHI Grant Number JP26400367 and JP16K05460, and program for leading graduate schools of ministry of education, culture, sports, science and technology-Japan.

Effect of impurities on kinetic transport processes in fusion plasmas

Energy Technology Data Exchange (ETDEWEB)

Braun, Stefanie

2010-12-10

Within the framework of this thesis, different problems arising in connection with impurities have been investigated. Collisional damping of zonal flows in tokamaks: Since the Coulomb collision frequency increases with increasing ion charge, heavy, highly charged impurities play an important role in this process. The effect of such impurities on the linear response of the plasma to an external potential perturbation, as caused by zonal flows, is calculated with analytical methods. In comparison with a pure plasma, the damping of the flows occurs, as expected, considerably faster; for experimentally relevant parameters, the enhancement exceeds the effective charge Z{sub eff} of the plasma. Impurity transport driven by microturbulence in tokamaks: With regard to impurities, it is especially important whether the resulting flows are directed inwards or outwards, since they are deleterious for core energy confinement on the one hand, but on the other hand help protecting plasma-facing components from too high energy fluxes in the edge region. A semi-analytical model is presented describing the resulting impurity fluxes and the stability boundary of the underlying mode. The main goal is to bridge the gap between, on the one hand, costly numerical simulations, which are applicable to a broad range of problems but yield scarcely traceable results, and, on the other hand, analytical theory, which might ease the interpretation of the results but is so far rather rudimentary. The model is based on analytical formulae whenever possible but resorts to a numerical treatment when the approximations necessary for an analytical solution would lead to a substantial distortion of the results. Both the direction of the impurity flux and the stability boundary are found to depend sensitively on the plasma parameters such as the impurity density and the temperature gradient. Pfirsch-Schlueter transport in stellarators: Due to geometry effects, collisional transport plays a much more

Soliton scatterings by impurities in a short-length sine-Gordon chain

International Nuclear Information System (INIS)

Dikande, A.M.; Kofane, T.C.

1995-07-01

The scattering of soliton by impurities at the frontiers of a finite-length region of an infinite sine-Gordon chain is analyzed. The impurities consist of two isotopic inhomogeneities installed at the boundaries of the finite-length region. The soliton solution in the region is found in term of snoidal sine-Gordon soliton which properly takes into account the effects of the boundaries. By contrast, the soliton solutions in the neighboring sides of the region are obtained in terms of the so-called large-amplitude, localized kinks with limiting spatial extensions at x → ± ∞, which is equal ±π. Using the continuity of these soliton solutions at the frontiers as well as appropriate boundary conditions, it is shown that the soliton may be either i) reflected by the incident impurity; ii) trapped (with oscillating motions) between the two impurities (i.e. inside the infinite region); or iii) transmitted by the second impurity into the third, infinitely extended region. The threshold velocities for the reflection and transmission into different regions are found and shown to vary exponentially as a function of the length of the bounded region. The frequency of soliton oscillations between the impurities has also been calculated in some acceptable limit. (author). 28 refs, 1 fig

Models for impurity production and transport in tokamaks

International Nuclear Information System (INIS)

Hogan, J.T.

1976-01-01

Models for the edge conditions which are commonly used in tokamak transport codes have been kept simple partly because of a lack of data. A report is presented on an improved model for the particle and energy balance of e - , H 1 + , H 1 0 , H 2 + , H 2 0 , O 0 , O/sup (1 yields 8) + / in the plasma scrape-off region. Experiments should yield the needed data in the near future, and allow one to test the model. The diffusion of impurities has been studied with a neoclassical model. The role of 'anomalous spreading' of the impurity distribution has been studied for the case of Fe. A model is presented for the expulsion of low-Z (oxygen) impurities for cases where q(0) greater than 1, but in which a large shear-free region is produced in the plasma core

Impurity sources in TEXTOR

Energy Technology Data Exchange (ETDEWEB)

Pospieszczyk, A; Bay, H L; Bogen, P; Hartwig, H; Hintz, E; Koenen, L; Ross, G G; Rusbueldt, D; Samm, U; Schweer, B

1987-02-01

The deuterium, oxygen and carbon fluxes from the main limiter and the deuterium fluxes from the wall are measured in TEXTOR for an 'all carbon' surrounding as a function of central density n/sub e/, of applied ICRH-power and of different wall conditions (carbonization). For this purpose, emission spectroscopy both with filter systems and spectrometers has been used. It is found that a major release mechanism for light impurities is via the formation of molecules. Oxygen seems to enter the discharge from the liner via O-D containing molecules, whereas the limiter acts as the main carbon source by the release of hydro-carbons as indicated by the observed CD-band spectra. Both oxygen and carbon fluxes are reduced by about a factor of two after a fresh carbonization. Above a certain critical density the plasma detaches from the limiter and forms a stable discharge with a radiation cooled boundary layer and with a major fraction of particles now reaching the wall instead of the limiter. The critical density rises with decreasing impurity fluxes or with increasing heating powers.

Impurity sources in TEXTOR

International Nuclear Information System (INIS)

Pospieszczyk, A.; Bay, H.L.; Bogen, P.; Hartwig, H.; Hintz, E.; Koenen, L.; Ross, G.G.; Rusbueldt, D.; Samm, U.; Schweer, B.

1987-01-01

The deuterium, oxygen and carbon fluxes from the main limiter and the deuterium fluxes from the wall are measured in TEXTOR for an 'all carbon' surrounding as a function of central density n e , of applied ICRH-power and of different wall conditions (carbonization). For this purpose, emission spectroscopy both with filter systems and spectrometers has been used. It is found that a major release mechanism for light impurities is via the formation of molecules. Oxygen seems to enter the discharge from the liner via O-D containing molecules, whereas the limiter acts as the main carbon source by the release of hydro-carbons as indicated by the observed CD-band spectra. Both oxygen and carbon fluxes are reduced by about a factor of two after a fresh carbonization. Above a certain critical density the plasma detaches from the limiter and forms a stable discharge with a radiation cooled boundary layer and with a major fraction of particles now reaching the wall instead of the limiter. The critical density rises with decreasing impurity fluxes or with increasing heating powers. (orig.)

A crystalline cluster method for deep impurities in insulators

International Nuclear Information System (INIS)

Guimaraes, P.S.

1983-01-01

An 'ab initio' self-consistent-field crystalline-cluster approach to the study of deep impurity states in insulators is proposed. It is shown that, in spite of being a cluster calculation, the interaction of the impurity with the crystal environment is fully taken into account. It is also shown that the present representation of the impurity states is, at least, as precise as the crystalline cluster representation of the pure crystal electronic structure. The procedure has been tested by performing the calculation of the electronic structure of the U center in a sodium chloride crystal, and it has been observed that the calculated GAMMA 1 - GAMMA 15 absorption energy is in good agreement with experiment. (Author) [pt

A crystalline cluster method for deep impurities in insulators

International Nuclear Information System (INIS)

Guimaraes, P.S.

1983-01-01

An ''ab initio'' self-consistent-field crysttalline-cluster approach to the study of deep impurity states in insulators is proposed. It is shown that, in spite of being a cluster calculation, the interaction of the impurity with the crystal environment is fully taken into account. It is also shown that the present representation of the impurity states is, at least, as precise as the crystalline cluster representation of the pure crystal electronic structure. The procedure has been tested by performing the calculation of the electronic structure of the U center in a sodium chloride crystal, and it has been observed that the calculated γ 1 - γ 15 absorption energy is in good agreement with experiment. (author) [pt

Experimental and gyrokinetic investigation of core impurity transport in Alcator C-mod

Science.gov (United States)

Howard, N.; Greenwald, M.; Podpaly, Y.; Reinke, M. L.; Rice, J. E.; White, A. E.; Mikkelsen, D. R.; Puetterich, T.

2010-11-01

A new multiple pulse laser blow-off system coupled with an upgraded high resolution x-ray spectrometer with spatial resolution allow for the most detailed studies of impurity transport on Alcator C-mod to date. Trace impurity injections created by the laser blow-off technique were introduced into plasmas with a wide range of parameters and time evolving profiles of He-like calcium were measured. The unique measurement of a single charge state profile and line integrated emission measurements from spectroscopic diagnostics were compared with the simulated emission from the impurity transport code STRAHL. A nonlinear least squares fitting routine was coupled with STRAHL, allowing for core impurity transport coefficients with errors to be determined. With this method, experimental data from trace calcium injections were analyzed and radially dependent, core values (< r/a ˜.6) of the diffusive and convective components of the impurity flux were obtained. The STRAHL results are compared with linear and global, nonlinear simulations from the gyrokinetic code GYRO. Results of this comparison and an investigation of the underlying physics associated with turbulent impurity transport will be presented.

Engineering and material aspects of impurity control systems

International Nuclear Information System (INIS)

Koski, J.A.

1985-01-01

The design of impurity control devices for fusion energy devices is discussed from the engineering and materials viewpoint. First, examples of impurity control devices are presented, and the plasma edge environment for which they are designed is briefly described. Materials concerns related to the design of the components are discussed and some currently proposed designs presented. Engineering tools available to the designer are listed, and some commonly encountered engineering analysis problems described

Method of plasma impurity control without magnetic divertor

International Nuclear Information System (INIS)

Schivell, J.F.

1977-06-01

A method is proposed for controlling impurity generation in a tokomak by skimming and pumping the scrape-off. This method avoids many of the complications of a magnetic divertor, such as specially configured magnetic fields, toroidal symmetry, and inefficient use of toroidal field volume. Estimates are given for operating parameters. Impurity reductions of as much as a factor of 10 should be achievable. The necessary high-capacity pump would employ either titanium gettering or cryocondensation

On the photo-ionization of impurity centres in semiconductors

International Nuclear Information System (INIS)

Tomak, M.

1982-10-01

The dependence of the photo-ionization cross-section on photon energy is calculated. The impurity potential is assumed to be of the Hulthen potential type and bound state wave function is calculated variationally. The results show that, at least in some cases, the Hulthen potential may describe the impurity better than the hydrogen or delta function potentials. (author)

Demixing of impurities and hydrogen as deduced from Zeff profiles in the boronized ASDEX

International Nuclear Information System (INIS)

Steuer, K.H.; Roehr, H.; Engelhardt, W.; Fussmann, G.; Kallenbach, A.; Kurzan, B.; Murmann, H.D.

1990-01-01

Substantial progress towards fusion has been made in the confinement, stability and heating of tokamak plasmas. The transport behaviour of magnetically confined plasmas, however, is still an unsolved problem. The transport mechanisms of hydrogen and of impurities are known to be different, leading to phenomena such as impurity accumulation on axis, especially in good confinement regimes, and more generally to demixing of the various species. Besides energy losses from impurity radiation, one has to be concerned about dilution of the fuel-ion density, and about effects that impurities may have on the main ion and electron transport. To understand the transport behaviour of the different plasma species, one needs their spatial density profiles. It is convenient to represent the various impurities by a characteristic impurity ion with a density n z and a fictive charge Z (Z = Σn i Z i 2 / Σn i Z i ; i ≥ 2). A typical value for Z is 7, indicating that light impurities are dominating. Comparing the different profiles, we find characteristic differences in the electron, proton and impurity transport behaviour. (orig./AH)

Simplified method for gravimetric determination of zirconium or hafnium with α-hydroxy carboxylic acids

International Nuclear Information System (INIS)

Barbieri, R.S.; Rocha, J.C.; Terra, V.R.; Marques Netto, A.

1989-01-01

The conditions for gravimetric determination of zirconium or hafnium by glicoloc acids derivatives were studied by thermogravimetric analysis. The method utilized shownd that after precipitation, washing and drying of precipitates at 150 o C, the resulting solid was weighed in the form of [M (RCH(OH)COO) 4 ] (M = Zr, Hf; R + C 6 H 5 , β-C 10 H 7 , p-BrC 6 H 4 ). (author)

Neutron activation determination of impurities in molybdenum

International Nuclear Information System (INIS)

Usmanova, M.M.; Mukhamedshina, N.M.; Obraztsova, T.V.; Saidakhmedov, K.Kh.

1984-01-01

Instrumental neutron-activation techniques of impurity element determination in molybdenum and MoO 3 (solid and powdered samples) have been developed. When determining impurities of Na, K, Mn, Cu, W, Re molybdenum has been irradiated by thermal neutrons in reactor for 20 min, the sample mass constituted 200-300 mg, sample cooling time after irradiation - 2.5-3.5 h. It is shown that in the process of Cr, Fe, Co, Zn determination the samples should be irradiated with thermal neutrons, and in the process of Sb, Ta and Ni determination - with resonance and fast neutrons. Simultaneous determination of the elements during irradiation with neutrons with reactor spectrum is possible. When determining P and S the samples are irradiated with thermal and epithermal neutrons and β-activity of samples and comparison samples are measured using β-spectrometer with anthracene crystal. The techniques developed permit to determine impurities in Mo with a relative standard deviation 0.07-0.15 and lower boundaries of contents determined - 10 -4 - 10 -7 %

Separation coefficients of liquid-vapor in systems formed by yttrium chloride with some impurities

International Nuclear Information System (INIS)

Volkov, V.T.; Nikiforova, T.V.; Nisel'son, L.A.; Telegin, G.F.

1990-01-01

Using equilibrium Rayleigh distillation in the 800-950 deg C temperature range, separation coefficients of liquid-vapor for systems, formed by yttrium chloride with Co, Cr, Ni, Mn, Fe, Cu, Na, K, Mg, Ca, Li impurities are determined. The impurity concentration lies within 0.02-0.4 mass. % limits of each impurity, and total impurity concentration does not exceed 1 mass. %. The tested impurities, except for calcium, are more volatile than the base, yttrium trichloride. In most systems negative deviation from the Raoult's law is observed

Application of secondary ion emission to impurity control in tokamaks

International Nuclear Information System (INIS)

Krauss, A.R.; Gruen, D.M.

1979-01-01

The extent to which high Z impurities enter the plasma of a magnetic confinement fusion device depends on the kinetic energy, angle of emission, and very importantly, the charge state of the ejected material. We have been studying both the fundamental process of secondary ion emission and possible techniques for producing surfaces which give rise to high ion fractions during sputtering, with a view to assessing the potential of this approach to impurity control in tokamaks. By carefully choosing materials exposed to fusion plasmas and by properly modifying the surface it may be possible to insure that nearly all the impurities are ejected as ions. As long as certain gas blanket configurations are avoided and especially if a divertor is used, it should then be possible to remove the impurities before they reach the plasma. The relative merits of a variety of materials are considered with regard to this application

Geometry-based multiplication correction for passive neutron coincidence assay of materials with variable and unknown (α,n) neutron rates

International Nuclear Information System (INIS)

Langner, D.G.; Russo, P.A.

1993-02-01

We have studied the problem of assaying impure plutonium-bearing materials using passive neutron coincidence counting. We have developed a technique to analyze neutron coincidence data from impure plutonium samples that uses the bulk geometry of the sample to correct for multiplication in samples for which the (α,n) neutron production rate is unknown. This technique can be applied to any impure plutonium-bearing material whose matrix constituents are approximately constant, whose self-multiplication is low to moderate, whose plutonium isotopic composition is known and not substantially varying, and whose bulk geometry is measurable or can be derived. This technique requires a set of reference materials that have well-characterized plutonium contents. These reference materials are measured once to derive a calibration that is specific to the neutron detector and the material. The technique has been applied to molten salt extraction residues, PuF 4 samples that have a variable salt matrix, and impure plutonium oxide samples. It is also applied to pure plutonium oxide samples for comparison. Assays accurate to 4% (1 σ) were obtained for impure samples measured in a High-Level Neutron Coincidence Counter II. The effects on the technique of variations in neutron detector efficiency with energy and the effects of neutron capture in the sample are discussed

Determination of molybdenum by the gravimetric plumbate method (with the molybdenum content from 50 % and above)

International Nuclear Information System (INIS)

Stepin, V.V.; Kurbatova, V.I.; Fedorova, N.D.

1980-01-01

A gravimetric method of molybdenum determination in ferromolybdenum (Mo content from 50% and higher) after its dissolving in HNO 3 is developed. The method is based on Mo deposition in acetic acid solution in the form of molybdenum oxide lead after separation of Fe and other interfering elements with sodium hydroxide [ru

Study on impurity screening in stochastic magnetic boundary of the Large Helical Device

International Nuclear Information System (INIS)

Kobayashi, M.; Morita, S.; Feng, Y.

2008-10-01

The impurity transport characteristics in the scrape-off layer associated with a stochastic magnetic boundary of LHD are analyzed. The remnant islands with very small internal field line pitch in the stochastic region play a key role in reducing the impurity influx. The thermal force driven impurity influx is significantly suppressed when the perpendicular energy flux exceeds the parallel one inside the islands due to the small pitch. Application of the 3D edge transport code, EMC3-EIRENE, confirmed the impurity retention (screening) effect in the edge region. It is also found that the edge surface layers are the most effective region to retain (screen) impurities because of the flow acceleration and plasma cooling via short flux tubes. The carbon emission obtained in experiments is in good agreement with the modelling results, showing the impurity retention (screening) potential of the stochastic magnetic boundary. (author)

Determination of impurities in magnesium and aluminium by X-ray fluorescence spectrometry

International Nuclear Information System (INIS)

Roca, M.; Diaz-Guerra, J.P.

1979-01-01

The determination of traces of Al, Cr, Cu, Fe, Mn, Ni, Pb, Si and of Bi, Cr, Cu, Fe, Ga, Mg, Mn, Ni, Pb, Si, Sn, Ti, V and Zn in samples of magnesium and aluminium, respectively, by means of X-ray fluorescence spectrometry, are studied. An automatic sequential spectrometer with an on-line computer for the treatment of data has been employed. The most suitable measurement parameters have been chosen for each element in order to achieve detection limits to a few p.p.m. For magnesium in the form of drillings the analyses are performed with satisfactory results for most impurities by pressing the samples into briquettes and employing metallic discs as standards. Correction methods for the spectral interferences of Ti on V, and V on Cr have been applied. (author)

Impurity penetration through the stochastic layer near the separatrix in tokamaks

International Nuclear Information System (INIS)

Morozov, D.K.; Herrera, J.J.E.; Rantsev-Kartinov, V.A.

1995-01-01

It is shown that a stochastic layer produced by ripple perturbations near the separatrix in tokamaks, leads to anomalous plasma flow out of the bulk plasma along perturbed field lines, which brings out impurities. This suggests that the stochastic layer may play a cleaning role. There is an opposite process of anomalous impurity diffusion into the plasma. The balance of these two processes defines the impurity concentration in the bulk plasma. copyright 1995 American Institute of Physics

Impact of the Injection Protocol on an Impurity's Stationary State

Science.gov (United States)

Gamayun, Oleksandr; Lychkovskiy, Oleg; Burovski, Evgeni; Malcomson, Matthew; Cheianov, Vadim V.; Zvonarev, Mikhail B.

2018-06-01

We examine stationary-state properties of an impurity particle injected into a one-dimensional quantum gas. We show that the value of the impurity's end velocity lies between zero and the speed of sound in the gas and is determined by the injection protocol. This way, the impurity's constant motion is a dynamically emergent phenomenon whose description goes beyond accounting for the kinematic constraints of the Landau approach to superfluidity. We provide exact analytic results in the thermodynamic limit and perform finite-size numerical simulations to demonstrate that the predicted phenomena are within the reach of the ultracold gas experiments.

Low-Z impurity transport in DIII-D - observations and implications

International Nuclear Information System (INIS)

Wade, M.R.; Houlberg, W.A.; Baylor, L.R.; West, W.P.; Baker, D.R.

2001-01-01

Impurity transport studies on DIII-D have revealed transport phenomena that are qualitatively consistent with that expected from turbulence transport theory in some cases and neoclassical transport theory in other cases. The transport model proposed here, which assumes that the total impurity transport is a linear sum of turbulence-driven transport and neoclassical transport, is shown to reproduce many of these observed features. This transport model is then applied to burn condition calculations, revealing that profile effects associated with neoclassical transport have a large effect on the maximum allowable impurity fraction in machines based on achieving neoclassical transport levels

Impurity transport and plasma rotation in the ISX-B tokamak

International Nuclear Information System (INIS)

Isler, R.C.; Murray, L.E.; Crume, E.C.

1983-01-01

Recent calculations have shown that when external momentum sources and plasma rotation are included in the neoclassical theory, the standard results for impurity transport can be strongly altered. Under appropriate conditions, inward convection is reduced by co-injection and enhanced by counter-injection. In order to examine the theoretical predictions, several observations of impurity transport have been made in the ISX-B tokamak during neutral-beam injection for comparison with the transport seen with Ohmic heating alone. Both intrinsic contaminants and deliberately introduced test impurities display a behaviour that is in qualitative agreement with the predicted beam-driven effects. These correlations are particularly noticeable when the comparisons are made for deuterium when the impurity transport in the Ohmically heated discharges exhibits neoclassical-like characteristics, i.e. accumulation and long confinement times. Similar but smaller effects are observed in beam-heated hydrogen discharges; neoclassical-like behaviour is not seen in Ohmically heated hydrogen sequences. Emphasis has been placed on measuring toroidal plasma rotation, and semiquantitative comparisons with the theories of beam-induced impurity transport have been made. It is possible that radial electric fields other than those associated with momentum transfer and increased anomalous processes during injection could also play a role. (author)

Impurity-defect induced noncentrosymmetricity in nonlinear optical processes

International Nuclear Information System (INIS)

Miah, M. Idrish

2009-01-01

Noncentrosymmetric nanosize-material processes in cadmium iodide are formed by doping it with the impurity copper. The noncentrosymmetricity in the processes are probed by the observation of the second-order optical susceptibility χ ijk (2) . The value of χ ijk (2) is found to depend fashionably on the impurity content of the nanomaterials. The results also show that a significant enhancement in the noncentrosymmetric response is achieved in nanomaterials with reduced sizes and at low temperatures.

Effect of impurities on vacancy migration energy in Fe-based alloys

International Nuclear Information System (INIS)

Hashimoto, N.; Sakuraya, S.; Tanimoto, J.; Ohnuki, S.

2014-01-01

Effects of impurities, such as carbon, nitrogen, helium and hydrogen, on microstructural evolution in pure iron were investigated by means of a multi-beam electron microscope. Growth rate of dislocation loops were measured to calculate vacancy migration energies. In all irradiation temperature conditions, both the size and the number density of dislocation loops were increased as a function of dose. Irradiation with more impurities showed an increase in the temperature dependence of the dislocation loop growth rate compared to irradiation with little impurities. The in situ experiment indicated that the net migration energy of vacancies could be increased due to trapping by impurities, and the effect of C and N on the migration energy of vacancy would be larger than that of W, V, Ta. Furthermore, H and He would increase vacancy migration energy greater than C and N, as well as W, V, Ta. The density functional theory (DFT), applied to the atomic models of BCC iron, indicated an increase in vacancy migration energy by the trapping of impurity atoms, that is a good agreement with this in situ experiment

Plasma Interactions with Mixed Materials and Impurity Transport

Energy Technology Data Exchange (ETDEWEB)

Rognlien, T. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Beiersdorfer, Peter [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chernov, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Frolov, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Magee, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rudd, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Umansky, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-10-28

The project brings together three discipline areas at LLNL to develop advanced capability to predict the impact of plasma/material interactions (PMI) on metallic surfaces in magnetic fusion energy (MFE) devices. These areas are (1) modeling transport of wall impurity ions through the edge plasma to the core plasma, (2) construction of a laser blow-off (LBO) system for injecting precise amounts of metallic atoms into a tokamak plasma, and (3) material science analysis of fundamental processes that modify metallic surfaces during plasma bombardment. The focus is on tungsten (W), which is being used for the ITER divertor and in designs of future MFE devices. In area (1), we have worked with the University of California, San Diego (UCSD) on applications of the UEDGE/DUSTT coupled codes to predict the influx of impurity ions from W dust through the edge plasma, including periodic edge-plasma oscillations, and revived a parallel version of UEDGE to speed up these simulations. In addition, the impurity transport model in the 2D UEDGE code has been implemented into the 3D BOUT++ turbulence/transport code to allow fundamental analysis of the impact of strong plasma turbulence on the impurity transport. In area (2), construction and testing of the LBO injection system has been completed. The original plan to install the LBO on the National Spherical Torus Experiment Upgrade (NSTX-U) at Princeton and its use to validate the impurity transport simulations is delayed owing to NSTX-U being offline for substantial magnetic coil repair period. In area (3), an analytic model has been developed to explain the growth of W tendrils (or fuzz) observed for helium-containing plasmas. Molecular dynamics calculations of W sputtering by W and deuterium (D) ions shows that a spatial blending of interatomic potentials is needed to describe the near-surface and deeper regions of the material.

Plasma Interactions with Mixed Materials and Impurity Transport

International Nuclear Information System (INIS)

Rognlien, T. D.; Beiersdorfer, Peter; Chernov, A.; Frolov, T.; Magee, E.; Rudd, R.; Umansky, M.

2016-01-01

The project brings together three discipline areas at LLNL to develop advanced capability to predict the impact of plasma/material interactions (PMI) on metallic surfaces in magnetic fusion energy (MFE) devices. These areas are (1) modeling transport of wall impurity ions through the edge plasma to the core plasma, (2) construction of a laser blow-off (LBO) system for injecting precise amounts of metallic atoms into a tokamak plasma, and (3) material science analysis of fundamental processes that modify metallic surfaces during plasma bombardment. The focus is on tungsten (W), which is being used for the ITER divertor and in designs of future MFE devices. In area (1), we have worked with the University of California, San Diego (UCSD) on applications of the UEDGE/DUSTT coupled codes to predict the influx of impurity ions from W dust through the edge plasma, including periodic edge-plasma oscillations, and revived a parallel version of UEDGE to speed up these simulations. In addition, the impurity transport model in the 2D UEDGE code has been implemented into the 3D BOUT++ turbulence/transport code to allow fundamental analysis of the impact of strong plasma turbulence on the impurity transport. In area (2), construction and testing of the LBO injection system has been completed. The original plan to install the LBO on the National Spherical Torus Experiment Upgrade (NSTX-U) at Princeton and its use to validate the impurity transport simulations is delayed owing to NSTX-U being offline for substantial magnetic coil repair period. In area (3), an analytic model has been developed to explain the growth of W tendrils (or fuzz) observed for helium-containing plasmas. Molecular dynamics calculations of W sputtering by W and deuterium (D) ions shows that a spatial blending of interatomic potentials is needed to describe the near-surface and deeper regions of the material.

Correlations between locked modes and impurity influxes

Energy Technology Data Exchange (ETDEWEB)

Fishpool, G M [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Lawson, K D [UKAEA Culham Lab., Abingdon (United Kingdom)

1994-07-01

An analysis of pulses that were disturbed by medium Z impurity influxes (Cl, Cr, Fe and Ni) recorded during the 91/92 JET operations, has demonstrated that such influxes can result in MHD modes which subsequently ``lock``. A correlation is found between the power radiated by the influx and the time difference between the start of the influx and the beginning of the locked mode. The growth in the amplitude of the locked mode itself can lead to further impurity influxes. A correlation is noted between intense influxes (superior to 10 MW) and the mode ``unlocking``. (authors). 4 refs., 4 figs.

Interaction between impurities in Ag dilute alloys

International Nuclear Information System (INIS)

Krolas, K.; Wodniecka, B.; Wodniecki, P.; Uniwersytet Jagiellonski, Krakow

1977-01-01

Time dependent perturbed angular correlation measurements of gamma radiation in 111 Cd after 111 In decay were performed in AgPd and AgPt alloys. The concentration of Pd or Pt atoms being the nearest neighbours to the probe atoms is much higher than that one deduced from random impurity distribution. This effect results from the attractive interaction between the In probe atoms and Pt or Pd impurity atoms in silver host lattice. The binding energy of InPd and InPt complexes was measured as 135 +- 9 meV and 171 +- 9 meV, respectively. (author)

Impurity studies in the advanced toroidal facility

International Nuclear Information System (INIS)

Isler, R.C.; Horton, L.D.; Crume, E.C.; Howe, H.C.; Voronov, G.S.

1989-01-01

Impurities have played an important role in the initial stages of operation of the Advanced Toroidal Facility. Cleanup practices have been adequate enough that plasmas heated by ECH only can be operated in a quasi-steady state; however, neutral beam injected plasmas always collapse to a low temperature. It is not clear whether impurity radiation is actually responsible for initiating the collapse, but at the time the stored energy reaches a maximum, there are indications of poloidal asymmetries in radiation from low ionization stages, such as observed in marfes, which could play a dominant role in the plasma evolution. 3 refs., 5 figs

Dynamics of an impurity in a one-dimensional lattice

International Nuclear Information System (INIS)

Massel, F; Kantian, A; Giamarchi, T; Daley, A J; Törmä, P

2013-01-01

We study the non-equilibrium dynamics of an impurity in a harmonic trap that is kicked with a well-defined quasi-momentum, and interacts with a bath of free fermions or interacting bosons in a one-dimensional lattice configuration. Using numerical and analytical techniques we investigate the full dynamics beyond linear response, which allows us to quantitatively characterize states of the impurity in the bath for different parameter regimes. These vary from a tightly bound molecular state in a strongly interacting limit to a polaron (dressed impurity) and a free particle for weak interactions, with composite behaviour in the intermediate regime. These dynamics and different parameter regimes should be readily realizable in systems of cold atoms in optical lattices. (paper)

Quasi-regular impurity distribution driven by charge-density wave

International Nuclear Information System (INIS)

Baldea, I.; Badescu, M.

1991-09-01

The displacive motion of the impurity distribution immersed into the one-dimensional system has recently been studied in detail as one kind of quasi-regularity driven by CDW. As a further investigation of this problem we develop here a microscopical model for a different kind of quasi-regular impurity distribution driven by CDW, consisting of the modulation in the probability of occupied sites. The dependence on impurity concentration and temperature of relevant CDW quantities is obtained. Data reported in the quasi-1D materials NbSe 3 and Ta 2 NiSe 7 (particularly, thermal hysteresis effects at CDW transition) are interpreted in the framework of the present model. Possible similarities to other physical systems are also suggested. (author). 38 refs, 7 figs

Dynamic conductivity modified by impurity resonant states in doping three-dimensional Dirac semimetals

Science.gov (United States)

Li, Shuai; Wang, Chen; Zheng, Shi-Han; Wang, Rui-Qiang; Li, Jun; Yang, Mou

2018-04-01

The impurity effect is studied in three-dimensional Dirac semimetals in the framework of a T-matrix method to consider the multiple scattering events of Dirac electrons off impurities. It has been found that a strong impurity potential can significantly restructure the energy dispersion and the density of states of Dirac electrons. An impurity-induced resonant state emerges and significantly modifies the pristine optical response. It is shown that the impurity state disturbs the common longitudinal optical conductivity by creating either an optical conductivity peak or double absorption jumps, depending on the relative position of the impurity band and the Fermi level. More importantly, these conductivity features appear in the forbidden region between the Drude and interband transition, completely or partially filling the Pauli block region of optical response. The underlying physics is that the appearance of resonance states as well as the broadening of the bands leads to a more complicated selection rule for the optical transitions, making it possible to excite new electron-hole pairs in the forbidden region. These features in optical conductivity provide valuable information to understand the impurity behaviors in 3D Dirac materials.

PROCESS FOR RECOVERY OF URANIUM VALUES FROM IMPURE SOLUTIONS THEREOF

Science.gov (United States)

Kilner, S.B.

1959-11-01

A process is presented for the recovery of uraninm values from impure solutions which are obtained, for example, by washing residual uranium salt or uranium metal deposits from stainless steel surfaces using an aqueous or certain acidic aqueous solutions. The solutions include uranyl and oxidized iron, chromium, nickel, and copper ions and may contain manganese, zinc, and silver ions. In accordance with one procedure. the uranyl ions are reduced to the uranous state, and the impurity ions are complexed with cyanide under acidic conditions. The solution is then treated with ammonium hydroxide or alkali metal hydroxide to precipitate uranous hydroxide away from the complexed impurity ions in the solution. Alternatively, an excess of alkali metal cyanide is added to the reduced solution until the solution becomes sufficiently alkaline for the uranons hydroxide to precipitate. An essential feature in operating the process is in maintaining the pH of the solution sufficiently acid during the complexing operation to prevent the precipitation of the impurity metal hydroxides.

Novel sound phenomena in superfluid helium in aerogel and other impure superfluids

International Nuclear Information System (INIS)

Brusov, Peter; Brusov, Paul; Lawes, Gavin; Lee, Chong; Matsubara, Akira; Ishikawa, Osamu; Majumdar, Pinaki

2003-01-01

During the last decade new techniques for producing impure superfluids with unique properties have been developed. This new class of systems includes superfluid helium confined to aerogel, HeII with different impurities (D 2 , N 2 , Ne, Kr), superfluids in Vycor glasses, and watergel. These systems exhibit very unusual properties including unexpected acoustic features. We discuss the sound properties of these systems and show that sound phenomena in impure superfluids are modified from those in pure superfluids. We calculate the coupling between temperature and pressure oscillations for impure superfluids and for superfluid He in aerogel. We show that the coupling between these two sound modes is governed either by c∂ρ/∂c or σρ a ρ s (for aerogel) rather than thermal expansion coefficient ∂ρ/∂T, which is enormously small in pure superfluids. This replacement plays a fundamental role in all sound phenomena in impure superfluids. It enhances the coupling between the two sound modes that leads to the existence of such phenomena as the slow mode and heat pulse propagation with the velocity of first sound observed in superfluids in aerogel. This means that it is possible to observe in impure superfluids such unusual sound phenomena as slow pressure (density) waves and fast temperature (entropy) waves. The enhancement of the coupling between the two sound modes decreases the threshold values for nonlinear processes as compared to pure superfluids. Sound conversion, which has been observed in pure superfluids only by shock waves should be observed at moderate sound amplitude in impure superfluids. Cerenkov emission of second sound by first sound (which never been observed in pure superfluids) could be observed in impure superfluids

Spectroscopic study of sources and control of impurities in TMX-U. Revision 1

International Nuclear Information System (INIS)

Yu, T.L.; Allen, S.L.; Moos, H.W.

1984-11-01

Two absolutely calibrated euv instruments have been used to study the impurity characteristics in the Tandem Mirror Experiment-Upgrade (TMX-U). One instrument is a spectrograph that measures the time histories of several impurity emission lines in a single plasma shot. The other instrument is a monochromator that measures time-resolved radial profiles of a particular impurity emission line. The common intrinsic impurities found in TMX-U are C, N, O, and Ti. It has been shown that a large fraction of oxygen and nitrogen in the plasma is associated with the neutral beams. The plasma wall is the main source of carbon. In general, the concentration of each of the impurities is low (<1%), and the power radiated by them is less than 10 kW, which is a small portion of the total input power to the plasma. The concentrations of the impurities can be reduced substantially by glow discharge cleaning and titanium gettering

Fermi-edge transmission resonance in graphene driven by a single Coulomb impurity.

Science.gov (United States)

Karnatak, Paritosh; Goswami, Srijit; Kochat, Vidya; Pal, Atindra Nath; Ghosh, Arindam

2014-07-11

The interaction between the Fermi sea of conduction electrons and a nonadiabatic attractive impurity potential can lead to a power-law divergence in the tunneling probability of charge through the impurity. The resulting effect, known as the Fermi edge singularity (FES), constitutes one of the most fundamental many-body phenomena in quantum solid state physics. Here we report the first observation of FES for Dirac fermions in graphene driven by isolated Coulomb impurities in the conduction channel. In high-mobility graphene devices on hexagonal boron nitride substrates, the FES manifests in abrupt changes in conductance with a large magnitude ≈e(2)/h at resonance, indicating total many-body screening of a local Coulomb impurity with fluctuating charge occupancy. Furthermore, we exploit the extreme sensitivity of graphene to individual Coulomb impurities and demonstrate a new defect-spectroscopy tool to investigate strongly correlated phases in graphene in the quantum Hall regime.

Impurity enrichment and radiative enhancement using induced SOL flow in DIII-D

International Nuclear Information System (INIS)

Wade, M.R.; West, W.P.; Wood, R.D.

1998-07-01

Experiments on DIII-D have demonstrated the efficacy of using induced scrap-off-layer (SOL) flow to preferentially enrich impurities in the divertor plasma. This SOL floe is produced through simultaneous deuterium gas injection at the midplane and divertor exhaust. Using this SOL flow, an improvement in enrichment (defined as the ratio of impurity fraction in the divertor to that in the plasma core) has been observed for all impurities in trace-level experiments (i.e., impurity level is non-perturbative), with the degree of improvement increasing with impurity atomic number. In the case of argon, exhaust gas enrichment using modest SOL flow is as high as 17. Using this induced SOL flow technique and argon injection, radiative plasmas have been produced that combine high radiation losses (P rad /P input > 70%), low core fuel dilution (Z eff E > 1.0 τ E,ITER93H )

Nonmagnetic impurities in magnetic superconductors

International Nuclear Information System (INIS)

Mineev, V.P.

1989-01-01

The magnetization and magnetic field arising around the nonmagnetic impurity in magnetic superconductor with triplet pairing are found. The relationship of these results with the data of recent (gm)sR experiments in heavy fermionic superconductor U 1 - x Th x Be 13 is presented

A binder-free NiCo2O4 nanosheet/3D elastic N-doped hollow carbon nanotube sponge electrode with high volumetric and gravimetric capacitances for asymmetric supercapacitors.

Science.gov (United States)

Tong, Hao; Yue, Shihong; Lu, Liang; Jin, Fengqiao; Han, Qiwei; Zhang, Xiaogang; Liu, Jie

2017-11-09

To increase the volumetric and gravimetric capacitances of supercapacitors, a new class of electrode materials with high electrochemical activity and favorable structures is extremely desired. In this work, a hollow novel nitrogen-doped 3D elastic single-walled carbon nanotube sponge (NSCS) which is ultra lightweight with the lowest density of 0.8 mg cm -3 , and has a high open surface structure for electrolyte accessibility and excellent compressible properties as the electrode scaffold has been successfully fabricated by the pyrolysis method which could produce the carbon nanotube sponge easily on a large scale without high-cost and time-consuming processes. Moreover, a NiCo 2 O 4 nanosheet supported on the NSCS has been successfully fabricated. The highest volumetric and gravimetric capacitance of this electrode is 790 F cm -3 at 1.43 g cm -3 and 1618 F g -1 at 0.54 g cm -3 with excellent cycling stability. The density of NiCo 2 O 4 /NSCS electrode was adjusted by mechanical compression and the most favorable density of the film for both high volumetric and gravimetric capacitances obtained was 1.21 g cm -3 . The thick NiCo 2 O 4 /NSCS film of 72 μm has been fabricated at this favorable density, presenting both high volumetric and gravimetric capacitances of 597 F cm -3 and 1074 F g -1 at 1 A g -1 , respectively, indicating that the structure of the NSCS is extremely feasible for obtaining a thick film electrode with excellent volumetric and gravimetric capacitances. Furthermore, an asymmetric supercapacitor of NiCo 2 O 4 /NSCS//NGN/CNTs was fabricated, exhibiting a high gravimetric energy density of 47.65 W h kg -1 at 536 W kg -1 and a volumetric energy density of 33.44 W h L -1 at 376.16 W L -1 .

Physical behaviors of impure atoms during relaxation of impure NiAl-based alloy grain boundary

International Nuclear Information System (INIS)

Zheng Liping; Jiang Bingyao; Liu Xianghuai; Li Douxing

2003-01-01

The Monte Carlo simulation with the energetics described by the embedded atom method has been employed to mainly study physical behaviors of boron atoms during relaxation of the Ni 3 Al-x at.% B grain boundary. During relaxation of impure Ni 3 Al grain boundaries, authors suggest that for different types of impure atoms (Mg, B, Cr and Zr atoms etc.), as the segregating species, they have the different behaviors, but as the inducing species, they have the same behaviors, i.e. they all induce Ni atoms to substitute Al atoms. Calculations show that at the equilibrium, when x(the B bulk concentration) increases from 0.1 to 0.9, the peak concentration of B increases, correspondently, the peak concentration of Ni maximizes but the valley concentration of Al minimizes, at x=0.5. The calculations also show the approximate saturation of Ni at the grain boundary at x=0.5

Occurrence and Characterization Microstructure of Iron Impurities in Halloysite.

Science.gov (United States)

Liu, Rong; Yan, Chunjie; Wang, Hongquan; Xiao, Guoqi; Tu, Dong

2015-09-01

The quality of the clays and over all halloysite are mostly associated with minor amounts of ferruginous impurities content, since this element gives an undesirable reddish color to the halloysite mineral. Hence, finding out the modes of occurrence of iron in halloysite is of prime importance in the value addition and optimum utilization of halloysite. In order to analyze the occurrence of iron impurities in halloysite, Transmission Electron Microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were combined with wet chemical analysis methods to study the low-grade halloysite. The results indicated that the mineral phases of iron impurities in the concentrates are mainly composed of amounts of magnetite, goethite and hematite. Two types of occurrences for iron impurities have been found. One is single crystalline mineral consist in the halloysite, which contains three different phases of Goethite FeO(OH) (44.75%), Magnetite Fe3O4 (27.43%) and Hematite Fe2O3 (31.96%). The other is amorphous Fe-Al-Si glial materials. This study is of significance in the theoretical research on the halloysite mineralogy and in the developmental practice of halloysite in coal measures.

Multiple x-ray diffraction applied to the study of crystal impurities

International Nuclear Information System (INIS)

Cardoso, L.P.

1983-06-01

The x-ray multiple diffraction technique is used in the study of impurities concentration and localization in the crystal lattice, implemented with the fundamental observation that the impurities cannot be distributed with the same spatial group symmetry of the crystal. This fact could introduce scattered intensity in the crystal reciprocal lattice forbidden nodes. This effect was effectively observed in multiple diffraction diagrams, where a reinforcement of the scattered intensity in the pure crystal is produced, when choosing conveniently the involved reflections. The reflectivity theory was developed in the kinematic case, which take into account the scattering by the impurities atoms, and the analysis showed that, in the first approximation, the impurities can influence both in the allowed and forbidden positions for the pure crystal. (L.C.J.A.)

Refractometry of TGS crystals doped with L-threonine impurity under uniaxial pressure

Energy Technology Data Exchange (ETDEWEB)

Stadnyk, V. I., E-mail: vasylstadnyk@ukr.net; Kiryk, Yu. I. [Lviv National University (Ukraine)

2013-07-15

The temperature and spectral dependences of the refractive indices of triglycine sulphate (TGS) crystals doped with L-threonine impurity have been investigated. It is established that the introduction of an impurity weakens the temperature dependence of refractive indices. The electronic polarizability, refractions, and parameters of UV oscillators of mechanically deformed impurity crystals are calculated. The temperature coefficients of the phase transition shift are determined.

Refractometry of TGS crystals doped with L-threonine impurity under uniaxial pressure

International Nuclear Information System (INIS)

Stadnyk, V. I.; Kiryk, Yu. I.

2013-01-01

The temperature and spectral dependences of the refractive indices of triglycine sulphate (TGS) crystals doped with L-threonine impurity have been investigated. It is established that the introduction of an impurity weakens the temperature dependence of refractive indices. The electronic polarizability, refractions, and parameters of UV oscillators of mechanically deformed impurity crystals are calculated. The temperature coefficients of the phase transition shift are determined

Gas chromatographic determination of impurities of inorganic compounds

International Nuclear Information System (INIS)

Drugov, Yu.S.

1985-01-01

Methods of concentration, separation, detection in gas chromatographic determination of impurities of inorganic compounds including low-boiling gases, reactive gases, organometallic compounds, free metals, anions, etc. are reviewed. Methods of reaction gas chromatography for determining reactive gases, water, anions, metal chelates are considered in detail as well as methods of reaction-sorption concentration and reaction gas extraction. The application of gas chromatograpny ior anaiysis of water and atmosphere contamination, for determination of impurities in highly pure solid substances and gases is described

Sensitivity of graphene flakes and nanorings to impurities

Energy Technology Data Exchange (ETDEWEB)

Konobeeva, N.N., E-mail: yana_nn@volsu.ru [Volgograd State University, University Avenue 100, Volgograd 400062 (Russian Federation); Belonenko, M.B. [Volgograd State University, University Avenue 100, Volgograd 400062 (Russian Federation); Volgograd Institute of Business, Uzhno-Ukrainskaya Str., Volgograd 400048 (Russian Federation)

2017-06-01

In this paper, we consider the influence of impurity on the graphene flakes and nanorings conductance. Based on the jumping Hamiltonian for graphene electrons with its direct diagonalization, we obtain the density of states. Further, the tunneling current is calculated for the following contacts: graphene flake-metal, graphene flake-quantum dots, graphene nanoring-quantum dots. We analyze the effect of the flake dimensions and the positions of the adsorbed molecule of impurity on the characteristic properties of the tunneling current.

Impurity-defect induced noncentrosymmetricity in nonlinear optical processes

Energy Technology Data Exchange (ETDEWEB)

Miah, M. Idrish, E-mail: m.miah@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

2009-12-15

Noncentrosymmetric nanosize-material processes in cadmium iodide are formed by doping it with the impurity copper. The noncentrosymmetricity in the processes are probed by the observation of the second-order optical susceptibility {chi}{sub ijk}{sup (2)}. The value of {chi}{sub ijk}{sup (2)} is found to depend fashionably on the impurity content of the nanomaterials. The results also show that a significant enhancement in the noncentrosymmetric response is achieved in nanomaterials with reduced sizes and at low temperatures.

Characterization of impurities in biogas before and after upgrading to vehicle fuel

Energy Technology Data Exchange (ETDEWEB)

Arrhenius, Karine; Johansson, Ulrika [SP Technical Research Institute of Sweden, Boraas (Sweden)

2012-01-15

Biogases produced by digesting organic wastes, residual sludge from waste water treatment, energy crops,byproducts from industry or in landfills contain impurities which can be harmful for components that will be in contact with the biogas during its utilization. In this project, the impurities present in biogases have been mapped out depending upon which feedstock is digested. P-cymene och D-limonene, two terpenes, have been found to be characteristics for biogases produced from the digestion of waste including household wastes while an 'oil' fraction containing alkanes with 9 to 13 carbon atoms is characteristic for biogases produced at waste water treatment plants. Ketones and sulfur compounds are found in biogases produced from the digestion of food industry wastes or energy crops. It was not possible to characterize impurities in biogases produced in farm plants digesting manure because not enough samples were analyzed from these plants. In order to understand the relation between the feedstock and the impurities present in the biogas, an extensive study on feedstock characterization must be conducted. One question to be answered is if these impurities only originate from the volatilization from the feedstock and in this case, why only these specific compounds are found at significant concentrations. In this study we have also studied how effective purification/upgrading techniques are to remove impurities that have been identified in biogases. En general comment is that the upgraded gas still contains a part of the characteristic impurities which have been identified for each feedstock at different levels of concentration depending on which technique has been used. The results show that activated carbon filters are more or less effective. Some of them can remove more than 90 % of the impurities while others remove less that 10 %. Results show also that the amine scrubber have very moderate effects on the impurities composition. In that case, the

Oxygen control systems and impurity purification in LBE: Learning from DEMETRA project

Energy Technology Data Exchange (ETDEWEB)

Brissonneau, L., E-mail: laurent.brissonneau@cea.fr [CEA/DEN, Cadarache, DTN/STPA/LIPC, F-13108 Saint-Paul-lez-Durance (France); Beauchamp, F.; Morier, O. [CEA/DEN, Cadarache, DTN/STPA/LIPC, F-13108 Saint-Paul-lez-Durance (France); Schroer, C.; Konys, J. [Karlsruher Institut fuer Technologie (KIT), Institut fuer Materialforschung III, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Kobzova, A.; Di Gabriele, F. [NRI, UJV Husinec-Rez 130, Rez 25068 (Czech Republic); Courouau, J.-L. [CEA/DEN, Saclay, DPC/SCCME/LECNA, F-919191 Gif-sur-Yvette (France)

2011-08-31

Operating a system using Lead-Bismuth Eutectic (LBE) requires a control of the dissolved oxygen concentration to avoid corrosion of structural materials and oxide build-up in the coolant. Reliable devices are therefore needed to monitor and adjust the oxygen concentration and to remove impurities during operation. In this article, we describe the learning gained from experiments run in the framework of the DEMETRA project (IP-EUROTRANS 6th FP contract) on the oxygen supply in LBE and on impurity filtration and management in different European facilities. An oxygen control device should supply oxygen in LBE at sufficient rate to compensate loss by surface oxidation, otherwise local dissolution of oxide layers might lead to the loss of steel protection against dissolution. Oxygen can be supplied by gas phase H{sub 2}O or O{sub 2}, or by solid phase, PbO dissolution. Each of these systems has substantial advantages and drawbacks. Considerations are given on devices for large scale facilities. The management of impurities (lead oxides and corrosion products) is also a crucial issue as their presence in the liquid phase or in the aerosols is likely to impair the facility, instrumentation and mechanical devices. To avoid impurity build-up on the long-term, purification of LBE is required to keep the impurity inventory low by trapping oxide and metallic impurities in specific filter units. On the basis of impurities characterisation and experimental results gained through filtration tests in different loops, this paper gives a description of the state-of-art knowledge of LBE purification with different filter media. It is now understood that the nature and behaviour of impurities formed in LBE will change according to the operating modes as well as the method to propose to remove impurities. This experience can be used to validate the basis filtration process, define the operating procedures and evaluate perspectives for the design of purification units for long

Interactions of structural defects with metallic impurities in multicrystalline silicon

International Nuclear Information System (INIS)

McHugo, S.A.; Thompson, A.C.; Hieslmair, H.

1997-01-01

Multicrystalline silicon is one of the most promising materials for terrestrial solar cells. It is critical to getter impurities from the material as well as inhibit contamination during growth and processing. Standard processing steps such as, phosphorus in-diffusion for p-n junction formation and aluminum sintering for backside ohmic contact fabrication, intrinsically possess gettering capabilities. These processes have been shown to improve L n values in regions of multicrystalline silicon with low structural defect densities but not in highly dislocated regions. Recent Deep Level Transient Spectroscopy (DLTS) results indirectly reveal higher concentrations of iron in highly dislocated regions while further work suggests that the release of impurities from structural defects, such as dislocations, is the rate limiting step for gettering in multicrystalline silicon. The work presented here directly demonstrates the relationship between metal impurities, structural defects and solar cell performance in multicrystalline silicon. Edge-defined Film-fed Growth (EFG) multicrystalline silicon in the as-grown state and after full solar cell processing was used in this study. Standard solar cell processing steps were carried out at ASE Americas Inc. Metal impurity concentrations and distributions were determined by use of the x-ray fluorescence microprobe (beamline 10.3.1) at the Advanced Light Source, Lawrence Berkeley National Laboratory. The sample was at atmosphere so only elements with Z greater than silicon could be detected, which includes all metal impurities of interest. Structural defect densities were determined by preferential etching and surface analysis using a Scanning Electron Microscope (SEM) in secondary electron mode. Mapped areas were exactly relocated between the XRF and SEM to allow for direct comparison of impurity and structural defect distributions

Self-consistent modeling of plasma response to impurity spreading from intense localized source

International Nuclear Information System (INIS)

Koltunov, Mikhail

2012-07-01

Non-hydrogen impurities unavoidably exist in hot plasmas of present fusion devices. They enter it intrinsically, due to plasma interaction with the wall of vacuum vessel, as well as are seeded for various purposes deliberately. Normally, the spots where injected particles enter the plasma are much smaller than its total surface. Under such conditions one has to expect a significant modification of local plasma parameters through various physical mechanisms, which, in turn, affect the impurity spreading. Self-consistent modeling of interaction between impurity and plasma is, therefore, not possible with linear approaches. A model based on the fluid description of electrons, main and impurity ions, and taking into account the plasma quasi-neutrality, Coulomb collisions of background and impurity charged particles, radiation losses, particle transport to bounding surfaces, is elaborated in this work. To describe the impurity spreading and the plasma response self-consistently, fluid equations for the particle, momentum and energy balances of various plasma components are solved by reducing them to ordinary differential equations for the time evolution of several parameters characterizing the solution in principal details: the magnitudes of plasma density and plasma temperatures in the regions of impurity localization and the spatial scales of these regions. The results of calculations for plasma conditions typical in tokamak experiments with impurity injection are presented. A new mechanism for the condensation phenomenon and formation of cold dense plasma structures is proposed.

Gold and Platinum in Silicon - Isolated Impurities Complexes

CERN Multimedia

Mcglynn, P

2002-01-01

%IS357 :\\\\ \\\\ Gold and platinum impurities in silicon are exploited for the control of minority carrier lifetimes, and this important feature has resulted in sustained research interest over several decades. Although the properties of isolated substitutional Au~atoms are well understood, this is not the case for Pt. Considerable uncertainty exists regarding the nature of several Pt related defects observed in Electron Paramagnetic Resonance~(EPR) and Photo~Luminescence~(PL). One of the objectives of this experiment is to exploit the transformation of radioactive Au isotopes as a means of producing specific Pt centres, and to use our thorough knowledge of Au in silicon to guide in the interpretation of data obtained for the centres when they transform to Pt.\\\\ \\\\ In addition to isolated impurities, the experiment also addresses the question of pairs of atoms formed by Au and Pt. Studies of these impurity pairs have been reported, but the benefits of a direct comparison of the defects in both the Au and Pt form...

Impurity production and transport in the boundary layer of tokamaks

International Nuclear Information System (INIS)

McCracken, G.M.

1987-01-01

The processes by which impurities are produced and enter the discharge are discussed. Emphasis is placed on sputtering at the limiter and an analytical global model is described which incorporates the self-stabilizing effects whch control the edge temperature. Predictions of the scaling of edge temperature and of total radiated power are compared with experimental data from JET and other tokamaks operating with limiters. Under many conditions the scaling of the edge conditions and of the radiated power is accurately predicted. Impurity transport in the boundary and the question of how to control the boundary layer is then discussed. The example of the Impurity Control Limiter on DITE is described. (author)

Reduction of impurities and activation of lithium orthosilicate breeder materials

International Nuclear Information System (INIS)

Knitter, Regina; Fischer, Ulrich; Herber, Stefan; Adelhelm, Christel

2009-01-01

The fabrication of lithium orthosilicate pebbles by melt-spraying enables a facile reprocessing of irradiated material by direct remelting. However, the necessary waiting period for the reprocessing is determined by the long-term activation of the material under irradiation that is dominated by the impurities. The activation characteristics for the current composition of lithium orthosilicate pebbles were assessed on the basis of three-dimensional activation calculations for a fusion power reactor. The calculations were used to identify critical amounts of impurities and were compared to the results of a hypothetical, pure material without impurities, as well as to a calculated Li-6 enriched OSi composition.

A gravimetric and an X-ray fluorescence method for the determination of rubidium in Rb2U(SO4)3

International Nuclear Information System (INIS)

Mudher, K.D.S.; Krishnan, K.; Jayadevan, N.C.

1993-01-01

Chemical characterization of rubidium uranium(IV) trisulfate, RB 2 U(SO 4 ) 3 , a new chemical assay standard for uranium requires accurate analysis of rubidium. A gravimetric and an X-ray fluorescence method (XRF) for the determination of rubidium in this compound are described. In the gravimetric method, rubidium is determined as Rb 2 Na[Co(NO 2 ) 6 ].H 2 O without separating uranium with a precision of the order of ±0.5%. In the XRF method, the concentration ratio of rubidium to uranium, C Rb /C U , is determined in the solid samples by the binary ratio method using calibration between intensity ratios (I Rb /I U ) and concentration ratios (C Rb /C U ). (author) 6 refs.; 2 figs.; 3 tabs

english title

International Nuclear Information System (INIS)

Esteban, Adolfo; Eppis, Maria Rosa

1996-01-01

One important parameter to specify in nuclear fuels is the oxygen-metal ratio, many tests were described in literature to determine it. Gravimetric methods are possibly the most used and usually a good precision was obtained analyzing sintered materials. However this method is affected by the humidity and impurities sorbed in the samples, especially in powders. The spectrophotometric methods determine oxygen-uranium ratio by measuring the absorbance of different ionic species in phosphoric acid. This technique is simply and is not affected by humidity and impurities. Owing to discrepancy in the results between both methods, it was carried out in our laboratory, a study on various gravimetric and spectrophotometric methods. Several assays and analysis were performed comparing test procedures, trying to obtain better precision and accuracy. This work presents the results obtained and the recommended procedure to use with sintered and unsintered materials. (author)

Modelling of impurity transport in ergodic layer of LHD

International Nuclear Information System (INIS)

Feng, Y.; Masuzaki, S.; Morisaki, T.; Ohyabu, N.; Yamada, H.; Komori, A.; Motojima, O.; Kobayashi, M.

2008-01-01

The impurity transport properties in the ergodic layer of LHD are analyzed by the 3D edge transport code as well as 1D simple model, which is used to illustrate the essential transport terms in the analysis. It is found that as the plasma density increases the edge surface layers, very edge region of the ergodic layer, enters friction dominant regime, resulting in impurity retention. It is considered that the cause for the retention is both temperature drop and the flow acceleration in the edge surface layers. The edge surface layers can provide effective retention of impurities coming from divertor as well as the first wall, because of the geometrical advantage of the edge region of LHD. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Interplay of light and heavy impurities in a fusion plasma

Energy Technology Data Exchange (ETDEWEB)

Gaja, Mustafa [IPP, Garching (Germany); Tokar, Mikhail [IEK4, Juelich FZ, Juelich (Germany)

2016-07-01

Radiation from impurities eroded from the walls can lead to a broad spectrum of spectacular phenomena in fusion devices An example of such events are breathing oscillations observed in the large helical device (LHD), in long pulse discharges with a stainless steel divertor. They were characterized with oscillations of a period of a second in various plasma parameters. By optimizing magnetic geometry this operation mode, leading to a deteriorate plasma performance, can be avoided. Nonetheless it is of interest and practical importance to understand and firmly predict conditions for breathing phenomenon, in particular, in view of similar impurity environment in W-7 X stellarator. A qualitative explanation for breathing oscillations proposed earlier presumes that they arise due to non-linear synergetic interplay of diverse physical processes. A one-dimensional non-stationary model, describing the generation and transport of main, impurity particles and heat by including the radiation of high-Z (Fe) and low-Z (C and O) impurities is elaborated here. The calculations predict the appearance of oscillations in the relevant range of plasma parameters, reproduce well experimentally observed amplitudes and period of oscillations. It demonstrates that the smaller the fraction of the plasma interaction with a stainless steel surface, the higher the light impurity concentration needed to excite the breathing oscillations. This shows a way to avoid oscillations in future experiments.

Risk evaluation of impurities in topical excipients: The acetol case

Directory of Open Access Journals (Sweden)

Jente Boonen

2014-10-01

Full Text Available Pharmaceutical excipients for topical use may contain impurities, which are often neglected from a toxicity qualification viewpoint. The possible impurities in the most frequently used topical excipients were evaluated in-silico for their toxicity hazard. Acetol, an impurity likely present in different topical pharmaceutical excipients such as propylene glycol and glycerol, was withheld for the evaluation of its health risk after dermal exposure.An ex-vivo in-vitro permeation study using human skin in a Franz Diffusion Cell set-up and GC as quantification methodology showed a significant skin penetration with an overall Kp value of 1.82×10−3 cm/h. Using these data, limit specifications after application of a dermal pharmaceutical product were estimated. Based on the TTC approach of Cramer class I substances, i.e. 1800 µg/(day∙person, the toxicity-qualified specification limits of acetol in topical excipients were calculated to be 90 µg/mL and 180 µg/mL for propylene glycol and glycerol, respectively.It is concluded that setting specification limits for impurities within a quality-by-design approach requires a case-by-case evaluation as demonstrated here with acetol. Keywords: Acetol, Impurity, Excipients, Transdermal penetration, Specification limits

Effect of light impurities on the early stage of swelling in austenitic stainless steel

International Nuclear Information System (INIS)

Igata, N.

1998-01-01

The objective of this study is to analyse the early stage of swelling and clarify the role of light impurities (nitrogen) in swelling of austenitic stainless steel. Recent results show that light impurities affect the swelling of 316 stainless steel under HVEM irradiation up to 10 dpa. At low concentration of light impurities the radiation swelling increases then decreases through the maximum as the concentration of light impurities increases. In the present paper the theoretical model is presented for the explanation of this effect. The model is based on the two factors: the influence of absorbed impurities on the voids caused by the production of an additional gas pressure in voids for their stabilization and the effect of impurities segregated around the surface of voids by the lowering of surface tension. These two affects are taken into account in the calculations of the critical size and the growth rate of cavities. The theoretical predictions on the radiation swelling rate dependent on the impurity concentration and temperature coincided with the experimental results on 316 stainless steel irradiated by HVEM. (orig.)

Behavior of oxygen impurities in tokamak. Vol. 2

Energy Technology Data Exchange (ETDEWEB)

El-Sharif, R N; Beket, A H [Plasma and Nuclear Fusion Department, Nuclear Research Center, Atomic Energy Aurhority, Cairo (Egypt)

1996-03-01

Impurity transport in tokamak plasma is a subject of great importance in present day tokamak experiments. The transport of oxygen as an impurity element in small tokamak was studied theoretically. The viscosity coefficient of oxygen has been calculated in different approximation 13 and 21 moment approximation, taking into consideration {chi}>>1,{chi}{omega}{sub c} {tau}. It was found that in 21 moment approximation additional terms added to the perturbation from equilibrium leads to increase in viscosity coefficients than in 13 moments approximation. 9 figs.

Influence of impurities on the fuel retention in fusion reactors

International Nuclear Information System (INIS)

Reinhart, Michael

2015-01-01

The topic of this thesis is the influence of plasma impurities on the hydrogen retention in metals, in the scope of plasma-wall-interaction research for fusion reactors. This is addressed experimentally and by modelling. The mechanisms of the hydrogen retention are influenced by various parameters like the wall temperature, ion energy, flux and fluence as well as the plasma composition. The plasma composition is a relevant factor for hydrogen retention in fusion reactors, as their plasma will also contain impurities like helium or seeded impurities like argon. The experiments treated in this thesis were performed in the linear plasma generator PSI-2 at Forschungszentrum Juelich, and are divided in 3 parts: The first experiments cover the plasma diagnostics, most importantly the measurement of the impurity ion concentration in the plasma by optical emission spectroscopy. This is a requirement for the later experiments with mixed plasmas. Diagnostics like Langmuir probe measurements are not applicable for this task because they do not distinguish different ionic species. The results also show that the impurity ion concentrations cannot be simply concluded from the neutral gas input to the plasma source, because the relation between the neutral gas concentration and impurity ion concentration is not linear. The second and main part of the experiments covers the exposure of tungsten samples to deuterium plasmas. In the experiments, the impurity ion type and concentration is variated, to verify the general influence of helium and argon on the deuterium retention in tungsten samples exposed at low temperatures. It shows that helium impurities reduce the amount of retained deuterium by a factor of 3, while argon impurities slightly increase the total retention, compared to exposures to a pure deuterium plasma. Cross-sections of the exposed tungsten surfaces via TEM-imaging reveal a 12-15 nm deep helium nanobubble layer at the surface of the sample, while for the cases of

Influence of impurities on the fuel retention in fusion reactors

Energy Technology Data Exchange (ETDEWEB)

Reinhart, Michael

2015-07-01

The topic of this thesis is the influence of plasma impurities on the hydrogen retention in metals, in the scope of plasma-wall-interaction research for fusion reactors. This is addressed experimentally and by modelling. The mechanisms of the hydrogen retention are influenced by various parameters like the wall temperature, ion energy, flux and fluence as well as the plasma composition. The plasma composition is a relevant factor for hydrogen retention in fusion reactors, as their plasma will also contain impurities like helium or seeded impurities like argon. The experiments treated in this thesis were performed in the linear plasma generator PSI-2 at Forschungszentrum Juelich, and are divided in 3 parts: The first experiments cover the plasma diagnostics, most importantly the measurement of the impurity ion concentration in the plasma by optical emission spectroscopy. This is a requirement for the later experiments with mixed plasmas. Diagnostics like Langmuir probe measurements are not applicable for this task because they do not distinguish different ionic species. The results also show that the impurity ion concentrations cannot be simply concluded from the neutral gas input to the plasma source, because the relation between the neutral gas concentration and impurity ion concentration is not linear. The second and main part of the experiments covers the exposure of tungsten samples to deuterium plasmas. In the experiments, the impurity ion type and concentration is variated, to verify the general influence of helium and argon on the deuterium retention in tungsten samples exposed at low temperatures. It shows that helium impurities reduce the amount of retained deuterium by a factor of 3, while argon impurities slightly increase the total retention, compared to exposures to a pure deuterium plasma. Cross-sections of the exposed tungsten surfaces via TEM-imaging reveal a 12-15 nm deep helium nanobubble layer at the surface of the sample, while for the cases of

Impurities enhance caking in lactose powder

DEFF Research Database (Denmark)

Carpin, M.; Bertelsen, H.; Dalberg, A.

2017-01-01

Caking of lactose and other dry ingredients is a common problem in the dairy and food industries. The lactose production process includes different purification steps, depending on the type of lactose produced. The aim of this study was therefore to investigate how the remaining impurities (i.......e. non-lactose components) affect the caking tendency of the final powder. The results from a combination of different methods, including dynamic vapor sorption, characterization of the physicochemical composition and assessment of caking with a ring shear tester, suggested humidity caking. Larger...... amounts of impurities in the lactose powder resulted in enhanced moisture sorption and greater caking tendency. These findings emphasize the importance of controlling the washing and purification steps throughout the production process in order to limit caking in the final product...

Investigation of impurity confinement in lower hybrid wave heated plasma on EAST tokamak

Science.gov (United States)

Xu, Z.; Wu, Z. W.; Zhang, L.; Gao, W.; Ye, Y.; Chen, K. Y.; Yuan, Y.; Zhang, W.; Yang, X. D.; Chen, Y. J.; Zhang, P. F.; Huang, J.; Wu, C. R.; Morita, S.; Oishi, T.; Zhang, J. Z.; Duan, Y. M.; Zang, Q.; Ding, S. Y.; Liu, H. Q.; Chen, J. L.; Hu, L. Q.; Xu, G. S.; Guo, H. Y.; the EAST Team

2018-01-01

The transient perturbation method with metallic impurities such as iron (Fe, Z  =  26) and copper (Cu, Z  =  29) induced in plasma-material interaction (PMI) procedure is used to investigate the impurity confinement characters in lower hybrid wave (LHW) heated EAST sawtooth-free plasma. The dependence of metallic impurities confinement time on plasma parameters (e.g. plasma current, toroidal magnetic field, electron density and heating power) are investigated in ohmic and LHW heated plasma. It is shown that LHW heating plays an important role in the reduction of the impurity confinement time in L-mode discharges on EAST. The impurity confinement time scaling is given as 42IP0.32Bt0.2\\overline{n}e0.43Ptotal-0.4~ on EAST, which is close to the observed scaling on Tore Supra and JET. Furthermore, the LHW heated high-enhanced-recycling (HER) H-mode discharges with ~25 kHz edge coherent modes (ECM), which have lower impurity confinement time and higher energy confinement time, provide promising candidates for high performance and steady state operation on EAST.

Behaviour of carbon-bearing impurity suspensions in sodium loops

Energy Technology Data Exchange (ETDEWEB)

Kozlov, F A; Zagorulko, Yu I; Alexseev, V V [Institute of Physics and Power Engineering, Obninsk (USSR)

1980-05-01

The experimental estimation results of the carbon-bearing impurity particle sizes in sodium by the sedimentometric analysis methods are presented. The techniques and results of the mass transfer calculations between the sodium flows contained the carbon-bearing impurity disperse phase, and the channel walls, the carbon particles solution kinetics and the soluble carbon near-wall concentration in channel with allowance for the flow-wall mass transfer processes, are given. (author)

Behaviour of carbon-bearing impurity suspensions in sodium loops

International Nuclear Information System (INIS)

Kozlov, F.A.; Zagorulko, Yu.I.; Alexseev, V.V.

1980-01-01

The experimental estimation results of the carbon-bearing impurity particle sizes in sodium by the sedimentometric analysis methods are presented. The techniques and results of the mass transfer calculations between the sodium flows contained the carbon-bearing impurity disperse phase, and the channel walls, the carbon particles solution kinetics and the soluble carbon near-wall concentration in channel with allowance for the flow-wall mass transfer processes, are given. (author)

Impurity flux collection at the plasma edge of the tokamak MT-1

International Nuclear Information System (INIS)

Hildebrandt, D.; Bakos, J.S.; Petravich, G.

1989-09-01

Fluxes of intrinsic and injected impurities and background plasma ions were collected using a bidirectional probe at the plasma edge of the tokamak MT-1. The directional and radial dependences of injected impurities and plasma ions were very similar indicating a strong coupling of the impurity transport to the dynamics of the background plasma. The measured intrinsic concentration of about 10 -4 for Mo at the plasma edge is derived. (author) 17 refs.; 5 figs

Instability of homogeneous distribution of charged substitutional impurity in semiconductors

International Nuclear Information System (INIS)

Vasilevskij, M.I.; Ershov, S.N.; Panteleev, V.A.

1985-01-01

A mechanism is suggested of instability of uniform impurity distribution in a semiconductor. The mechanism is associated with the vacancy wind effect and deflection from local neutrality in case of impurity concentration fluctuation occurrence. It is shown that the mechanism can be realized by irradiation of silicon doped with group-3 and group 5 elements

Stability-indicating HPLC-DAD/UV-ESI/MS impurity profiling of the anti-malarial drug lumefantrine.

Science.gov (United States)

Verbeken, Mathieu; Suleman, Sultan; Baert, Bram; Vangheluwe, Elien; Van Dorpe, Sylvia; Burvenich, Christian; Duchateau, Luc; Jansen, Frans H; De Spiegeleer, Bart

2011-02-28

Lumefantrine (benflumetol) is a fluorene derivative belonging to the aryl amino alcohol class of anti-malarial drugs and is commercially available in fixed combination products with β-artemether. Impurity characterization of such drugs, which are widely consumed in tropical countries for malaria control programmes, is of paramount importance. However, until now, no exhaustive impurity profile of lumefantrine has been established, encompassing process-related and degradation impurities in active pharmaceutical ingredients (APIs) and finished pharmaceutical products (FPPs). Using HPLC-DAD/UV-ESI/ion trap/MS, a comprehensive impurity profile was established based upon analysis of market samples as well as stress, accelerated and long-term stability results. In-silico toxicological predictions for these lumefantrine related impurities were made using Toxtree® and Derek®. Several new impurities are identified, of which the desbenzylketo derivative (DBK) is proposed as a new specified degradant. DBK and the remaining unspecified lumefantrine related impurities are predicted, using Toxtree® and Derek®, to have a toxicity risk comparable to the toxicity risk of the API lumefantrine itself. From unstressed, stressed and accelerated stability samples of lumefantrine API and FPPs, nine compounds were detected and characterized to be lumefantrine related impurities. One new lumefantrine related compound, DBK, was identified and characterized as a specified degradation impurity of lumefantrine in real market samples (FPPs). The in-silico toxicological investigation (Toxtree® and Derek®) indicated overall a toxicity risk for lumefantrine related impurities comparable to that of the API lumefantrine itself.

A pharmacology guided approach for setting limits on product-related impurities for bispecific antibody manufacturing.

Science.gov (United States)

Rajan, Sharmila; Sonoda, Junichiro; Tully, Timothy; Williams, Ambrose J; Yang, Feng; Macchi, Frank; Hudson, Terry; Chen, Mark Z; Liu, Shannon; Valle, Nicole; Cowan, Kyra; Gelzleichter, Thomas

2018-04-13

bFKB1 is a humanized bispecific IgG1 antibody, created by conjoining an anti-Fibroblast Growth Factor Receptor 1 (FGFR1) half-antibody to an anti-Klothoβ (KLB) half-antibody, using the knobs-into-holes strategy. bFKB1 acts as a highly selective agonist for the FGFR1/KLB receptor complex and is intended to ameliorate obesity-associated metabolic defects by mimicking the activity of the hormone FGF21. An important aspect of the biologics product manufacturing process is to establish meaningful product specifications regarding the tolerable levels of impurities that copurify with the drug product. The aim of the current study was to determine acceptable levels of product-related impurities for bFKB1. To determine the tolerable levels of these impurities, we dosed obese mice with bFKB1 enriched with various levels of either HMW impurities or anti-FGFR1-related impurities, and measured biomarkers for KLB-independent FGFR1 signaling. Here, we show that product-related impurities of bFKB1, in particular, high molecular weight (HMW) impurities and anti-FGFR1-related impurities, when purposefully enriched, stimulate FGFR1 in a KLB-independent manner. By taking this approach, the tolerable levels of product-related impurities were successfully determined. Our study demonstrates a general pharmacology-guided approach to setting a product specification for a bispecific antibody whose homomultimer-related impurities could lead to undesired biological effects. Copyright © 2018. Published by Elsevier Inc.

Isotope effects of trapped electron modes in the presence of impurities in tokamak plasmas

Science.gov (United States)

Shen, Yong; Dong, J. Q.; Sun, A. P.; Qu, H. P.; Lu, G. M.; He, Z. X.; He, H. D.; Wang, L. F.

2016-04-01

The trapped electron modes (TEMs) are numerically investigated in toroidal magnetized hydrogen, deuterium and tritium plasmas, taking into account the effects of impurity ions such as carbon, oxygen, helium, tungsten and others with positive and negative density gradients with the rigorous integral eigenmode equation. The effects of impurity ions on TEMs are investigated in detail. It is shown that impurity ions have substantially-destabilizing (stabilizing) effects on TEMs in isotope plasmas for {{L}ez}\\equiv {{L}ne}/{{L}nz}>0 (TEM turbulences in hydrogenic isotope plasmas with and without impurities are performed. The relations between the maximum growth rate of the TEMs with respect to the poloidal wave number and the ion mass number are given in the presence of the impurity ions. The results demonstrate that the maximum growth rates scale as {γ\\max}\\propto Mi-0.5 in pure hydrogenic plasmas. The scale depends on the sign of its density gradient and charge number when there is a second species of (impurity) ions. When impurity ions have density profiles peaking inwardly (i.e. {{L}ez}\\equiv {{L}ne}/{{L}nz}>0 ), the scaling also depends on ITG parameter {ηi} . The maximum growth rates scale as {γ\\max}\\propto M\\text{eff}-0.5 for the case without ITG ({ηi}=0 ) or the ITG parameter is positive ({ηi}>0 ) but the impurity ion charge number is low (Z≤slant 5.0 ). However, when {ηi}>0 and the impurity ion charge number is moderate (Z=6.0-8.0 ), the scaling law is found as {γ\\max}\\propto M\\text{eff}-1.0 . Here, Z is impurity ion charge number, and the effective mass number, {{M}\\text{eff}}=≤ft(1-{{f}z}\\right){{M}i}+{{f}z}{{M}z} , with {{M}i} and {{M}Z} being the mass numbers of the hydrogenic and impurity ions, respectively, and {{f}z}=Z{{n}0z}/{{n}0e} being the charge concentration of impurity ions. In addition, with regard to the case of {{L}ez}<0 , the maximum growth rate scaling is {γ\\max}\\propto Mi-0.5 . The possible relations of the results

Impurity Deionization Effects on Surface Recombination DC Current-Voltage Characteristics in MOS Transistors

International Nuclear Information System (INIS)

Chen Zuhui; Jie Binbin; Sah Chihtang

2010-01-01

Impurity deionization on the direct-current current-voltage characteristics from electron-hole recombination (R-DCIV) at SiO 2 /Si interface traps in MOS transistors is analyzed using the steady-state Shockley-Read-Hall recombination kinetics and the Fermi distributions for electrons and holes. Insignificant distortion is observed over 90% of the bell-shaped R-DCIV curves centered at their peaks when impurity deionization is excluded in the theory. This is due to negligible impurity deionization because of the much lower electron and hole concentrations at the interface than the impurity concentration in the 90% range. (invited papers)

Impurity effects on the grain boundary cohesion in copper

Science.gov (United States)

Li, Yunguo; Korzhavyi, Pavel A.; Sandström, Rolf; Lilja, Christina

2017-12-01

Segregated impurities at grain boundaries can dramatically change the mechanical behavior of metals, while the mechanism is still obscure in some cases. Here, we suggest a unified approach to investigate segregation and its effects on the mechanical properties of polycrystalline alloys using the example of 3 s p impurities (Mg, Al, Si, P, or S) at a special type Σ 5 (310 )[001 ] tilt grain boundary in Cu. We show that for these impurities segregating to the grain boundary, the strain contribution to the work of grain boundary decohesion is small and that the chemical contribution correlates with the electronegativity difference between Cu and the impurity. The strain contribution to the work of dislocation emission is calculated to be negative, while the chemical contribution is calculated to be always positive. Both the strain and chemical contributions to the work of dislocation emission generally become weaker with the increasing electronegativity from Mg to S. By combining these contributions together, we find, in agreement with experimental observations, that a strong segregation of S can reduce the work of grain boundary separation below the work of dislocation emission, thus embrittling Cu, while such an embrittlement cannot be produced by a P segregation because it lowers the energy barrier for dislocation emission relatively more than for work separation.

Assessment of Embrittlement of VHTR Structural Alloys in Impure Helium Environments

Energy Technology Data Exchange (ETDEWEB)

Crone, Wendy; Cao, Guoping; Sridhara, Kumar

2013-05-31

The helium coolant in high-temperature reactors inevitably contains low levels of impurities during steady-state operation, primarily consisting of small amounts of H{sub 2}, H{sub 2}O, CH{sub 4}, CO, CO{sub 2}, and N{sub 2} from a variety of sources in the reactor circuit. These impurities are problematic because they can cause significant long-term corrosion in the structural alloys used in the heat exchangers at elevated temperatures. Currently, the primary candidate materials for intermediate heat exchangers are Alloy 617, Haynes 230, Alloy 800H, and Hastelloy X. This project will evaluate the role of impurities in helium coolant on the stress-assisted grain boundary oxidation and creep crack growth in candidate alloys at elevated temperatures. The project team will: • Evaluate stress-assisted grain boundary oxidation and creep crack initiation and crack growth in the temperature range of 500-850°C in a prototypical helium environment. • Evaluate the effects of oxygen partial pressure on stress-assisted grain boundary oxidation and creep crack growth in impure helium at 500°C, 700°C, and 850°C respectively. • Characterize the microstructure of candidate alloys after long-term exposure to an impure helium environment in order to understand the correlation between stress-assisted grain boundary oxidation, creep crack growth, material composition, and impurities in the helium coolant. • Evaluate grain boundary engineering as a method to mitigate stress-assisted grain boundary oxidation and creep crack growth of candidate alloys in impure helium. The maximum primary helium coolant temperature in the high-temperature reactor is expected to be 850-1,000°C.Corrosion may involve oxidation, carburization, or decarburization mechanisms depending on the temperature, oxygen partial pressure, carbon activity, and alloy composition. These corrosion reactions can substantially affect long-term mechanical properties such as crack- growth rate and fracture

GRAVIMETRIC-DETERMINATION OF THE WATER CONCENTRATION IN WHOLE-BLOOD, PLASMA AND ERYTHROCYTES AND CORRELATIONS WITH HEMATOLOGICAL AND CLINICOCHEMICAL PARAMETERS

NARCIS (Netherlands)

LIJNEMA, TH; HUIZENGA, [No Value; JAGER, J; MACKOR, AJ; GIPS, CH

1993-01-01

We have assessed gravimetric methods for determination of intravascular water, established whole blood-, plasma- and erythrocyte water reference values in a healthy volunteer group (n = 97, 48 females) and correlated these variables with 30 simultaneous hematological, clinicochemical and body

A model of magnetic impurities within the Josephson junction of a phase qubit

Energy Technology Data Exchange (ETDEWEB)

Erickson, R P; Pappas, D P [National Institute of Standards and Technology, Boulder, CO 80305 (United States)

2010-02-15

We consider a superconducting phase qubit consisting of a monocrystalline sapphire Josephson junction with its symmetry axis perpendicular to the junction interfaces. Via the London gauge, we present a theoretical model of Fe{sup 3+} magnetic impurities within the junction that describes the effect of a low concentration of such impurities on the operation of the qubit. Specifically, we derive an interaction Hamiltonian expressed in terms of angular momentum states of magnetic impurities and low-lying oscillator states of a current-biased phase qubit. We discuss the coupling between the qubit and impurities within the model near resonance. When the junction is biased at an optimal point for acting as a phase qubit, with a phase difference of {pi}/2 and impurity concentration no greater than 0.05%, we find only a slight decrease in the Q factor of less than 0.01%.

Impurity doping effects on the orbital thermodynamic properties of hydrogenated graphene, graphane, in Harrison model

Science.gov (United States)

Yarmohammadi, Mohsen

2016-12-01

Using the Harrison model and Green's function technique, impurity doping effects on the orbital density of states (DOS), electronic heat capacity (EHC) and magnetic susceptibility (MS) of a monolayer hydrogenated graphene, chair-like graphane, are investigated. The effect of scattering between electrons and dilute charged impurities is discussed in terms of the self-consistent Born approximation. Our results show that the graphane is a semiconductor and its band gap decreases with impurity. As a remarkable point, comparatively EHC reaches almost linearly to Schottky anomaly and does not change at low temperatures in the presence of impurity. Generally, EHC and MS increases with impurity doping. Surprisingly, impurity doping only affects the salient behavior of py orbital contribution of carbon atoms due to the symmetry breaking.

Lattice site location of electrical dopant impurities in group-III nitrides

CERN Document Server

Amorim, Lígia; Temst, Kristiaan; Wahl, Ulrich

Dopants are impurities introduced in semiconductors in small quantities to tailor the material characteristics, the effects of which depend on the exact site the dopant occupies in the crystal lattice. The lattice location of impurities is, thus, crucial for the overall understanding of the semiconductor characteristics. In general, several techniques can be used to investigate the lattice site of an impurity, the most accurate and dedicated being emission channeling. However, a characteristic of this technique is that it requires the implantation of radioactive probes, usually created and accelerated in a radioactive ion beam facility. In some cases, emission channeling might however be the only technique capable to investigate the lattice sites occupied by the impurity atoms, provided an appropriate isotope for this technique can be used. For instance, the use of other methods such as Rutherford backscattering spectrometry, perturbed angular correlations, Mössbauer spectroscopy and extended X-ray absorptio...

Non-Fermi-liquid behavior: Exact results for ensembles of magnetic impurities

CERN Document Server

Zvyagin, A A

2002-01-01

In this work we consider several exactly solvable models of magnetic impurities in critical quantum antiferromagnetic spin chains and multichannel Kondo impurities. Their ground state properties are studied and the finite set of nonlinear integral equations, which exactly describe the thermodynamics of the models, is constructed. We obtain several analytic low-energy expressions for the temperature, magnetic field, and frequency dependences of important characteristics of exactly solvable disordered quantum spin models and disordered multichannel Kondo impurities with essential many-body interactions. We show that the only low-energy parameter that gets renormalized is the velocity of the low-lying excitations (or the effective crossover scale connected with each impurity); the others appear to be universal. In our study several kinds of strong disorder important for experiments were used. Some of them produce low divergences in certain characteristics of our strongly disordered critical systems (compared wit...

Impurity characterization of magnesium diuranate using simultaneous TG–DTA–FTIR measurements

Energy Technology Data Exchange (ETDEWEB)

Raje, Naina, E-mail: nraje@barc.gov.in [Analytical Chemistry Division, B.A.R.C., Mumbai 400 085 (India); Ghonge, Darshana K. [Analytical Chemistry Division, B.A.R.C., Mumbai 400 085 (India); Hemantha Rao, G.V.S. [NFC, ECIL Post, Hyderabad (India); Reddy, A.V.R. [Analytical Chemistry Division, B.A.R.C., Mumbai 400 085 (India)

2013-05-15

Current studies describe the application of simultaneous thermogravimetry–differential thermal analysis – evolved gas analysis techniques for the compositional characterization of magnesium diuranate (MDU) with respect to the impurities present in the matrix. The stoichiometric composition of MDU was identified as MgU{sub 2}O{sub 7}⋅3H{sub 2}O. Presence of carbonate and sulphate as impurities in the matrix was confirmed through the evolved gas analysis using Fourier Transformation Infrared Spectrometry detection. Carbon and magnesium hydroxide content present as impurities in magnesium diuranate have been determined quantitatively using TG and FTIR techniques and the results are in good agreement. Powder X-ray diffraction analysis of magnesium diuranate suggests the presence of magnesium hydroxide as impurity in the matrix. Also these studies confirm the formation of magnesium uranate, uranium sesquioxide and uranium dioxide above 1000 °C, due to the decomposition of magnesium diuranate.

Nature of impurities in fertilizers containing EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+) chelates.

Science.gov (United States)

Alvarez-Fernández, Ana; Cremonini, Mauro A; Sierra, Miguel A; Placucci, Giuseppe; Lucena, Juan J

2002-01-16

Iron chelates derived from ethylenediaminedi(o-hydroxyphenylacetic) acid (EDDHA), ethylenediaminedi(o-hydroxy-p-methylphenylacetic) acid (EDDHMA), ethylenediaminedi(2-hydroxy-5-sulfophenylacetic) acid (EDDHSA), and ethylenediaminedi(5-carboxy-2-hydroxyphenylacetic) acid (EDDCHA) are remarkably efficient in correcting iron chlorosis in plants growing in alkaline soils. This work reports the determination of impurities in commercial samples of fertilizers containing EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+). The active components (EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+)) were separated easily from other compounds present in the fertilizers by HPLC. Comparison of the retention times and the UV-visible spectra of the peaks obtained from commercial EDDHSA/Fe(3+) and EDDCHA/Fe(3+) samples with those of standard solutions showed that unreacted starting materials (p-hydroxybenzenesulfonic acid and p-hydroxybenzoic acid, respectively) were always present in the commercial products. 1D and 2D NMR experiments showed that commercial fertilizers based on EDDHMA/Fe(3+) contained impurities having structures tentatively assigned to iron chelates of two isomers of EDDHMA. These findings suggest that current production processes of iron chelates used in agriculture need to be improved.

Analysis of impurity effect on Silicide fuels of the RSG-GAS core

International Nuclear Information System (INIS)

Tukiran-Surbakti

2003-01-01

Simulation of impurity effect on silicide fuel of the RSG-GAS core has been done. The aim of this research is to know impurity effect of the U-234 and U-236 isotopes in the silicide fuels on the core criticality. The silicide fuels of 250 g U loading and 19.75 of enrichment is used in this simulation. Cross section constant of fuels and non-structure material of core are generated by WIMSD/4 computer code, meanwhile impurity concentration was arranged from 0.01% to 2%. From the result of analysis can be concluded that the isotopes impurity in the fuels could make trouble in the core and the core can not be operated at critical after a half of its cycle length (350 MW D)

Impurity engineering of Czochralski silicon used for ultra large-scaled-integrated circuits

Science.gov (United States)

Yang, Deren; Chen, Jiahe; Ma, Xiangyang; Que, Duanlin

2009-01-01

Impurities in Czochralski silicon (Cz-Si) used for ultra large-scaled-integrated (ULSI) circuits have been believed to deteriorate the performance of devices. In this paper, a review of the recent processes from our investigation on internal gettering in Cz-Si wafers which were doped with nitrogen, germanium and/or high content of carbon is presented. It has been suggested that those impurities enhance oxygen precipitation, and create both denser bulk microdefects and enough denuded zone with the desirable width, which is benefit of the internal gettering of metal contamination. Based on the experimental facts, a potential mechanism of impurity doping on the internal gettering structure is interpreted and, a new concept of 'impurity engineering' for Cz-Si used for ULSI is proposed.

Highly Selective Polypyrrole MIP-Based Gravimetric and Electrochemical Sensors for Picomolar Detection of Glyphosate