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Sample records for 2-deoxy-2-chloro-d-glucose impurity analysis

  1. Cryogenic Laser Calorimetry for Impurity Analysis

    NASA Technical Reports Server (NTRS)

    Swimm, R. T.

    1985-01-01

    The results of a one-year effort to determine the applicability of laser-calorimetric spectroscopy to the study of deep-level impurities in silicon are presented. Critical considerations for impurity analysis by laser-calorimetric spectroscopy are discussed, the design and performance of a cryogenic laser calorimeter is described, and measurements of background absorption in high-purity silicon are presented.

  2. Gas chromatographic analysis of trace gas impurities in tungsten hexafluoride.

    PubMed

    Laurens, J B; de Coning, J P; Swinley, J M

    2001-03-01

    Highly reactive fluorinated gaseous matrices require special equipment and techniques for the gas chromatographic analysis of trace impurities in these gases. The impurities that were analysed at the low-microg/l levels included oxygen, nitrogen, carbon dioxide, carbon monoxide, sulfur hexafluoride and hydrogen. This paper describes the use of a system utilising backflush column switching to protect the columns and detectors in the analysis of trace gas impurities in tungsten hexafluoride. Two separate channels were used for the analysis of H2, O2, N2, CO, CO2 and SF6 impurities with pulsed discharge helium ionisation detection. PMID:11269587

  3. Improved analysis of impurity transport coefficient profiles

    NASA Astrophysics Data System (ADS)

    Chilenski, M. A.; Greenwald, M.; Marzouk, Y.; Howard, N. T.; Rice, J.; White, A. E.

    2015-11-01

    Work is underway on the development of a novel technique to estimate impurity transport coefficient profiles and their uncertainties. Inference of impurity transport coefficient profiles using x-ray imaging crystal spectroscopy measurements of laser blow-off impurity injections has played a key role in the validation of gyrokinetic simulations of impurity transport in L-mode (Howard et al. 2012, Nucl. Fusion 52, 063002). Recent attempts to apply the existing methodology for interpreting such measurements to H-mode have failed to yield reliable estimates, however. This failure exposes key issues regarding the uniqueness of the solution and the rigorous estimation of the uncertainty. A new approach is under development which uses a combination of Markov chain Monte Carlo (MCMC) and global optimization techniques to estimate impurity transport coefficient profiles even when there are multiple possible solutions. This poster will present the new methodology in detail and will show preliminary results from applying it to Alcator C-Mod data. This new approach will enable us to test the existing understanding of L-mode impurity transport and to move towards multichannel validation of gyrokinetic simulations of H-modes. Supported by USDOE award DE-FC02-99ER54512.

  4. Structural analysis of an impurity of the drug landiolol.

    PubMed

    Štujber, Michal; Beldar, Sagar; Rabong, Constantin; Beseda, Igor; Breza, Martin; Liptaj, Tibor

    2014-03-01

    In a course of development and preparation of landiolol (1a), a known ultra-short-acting β-blocker, process quality control by HPLC and LC-MS analysis consistently showed an impurity peak ranging from 0.05% to 0.15 % and exhibiting a molecular mass m/z 887. To identify the hitherto unknown impurity, we prepared one of the possible landiolol derivatives with the same molecular mass for proper spectral characterization (NMR and MS). Its equivalence with the unknown impurity was then confirmed by LC-MS analysis. Ultimately, using fragmentation patterns in LC-MS and selective two-dimensional NMR experiments, the structure of the impurity was assigned as [(4S)-2,2-dimethyl-1,3-dioxolan-4-yl]methyl 3-{4-[(2S)-2-hydroxy-3-(3-{4-[(2S)-2-hydroxy-3-[(2-{[(morpholin-4-yl)carbonyl]amino}ethyl)amino]propoxy]phenyl}-N-(2-{[(morpholin-4-yl)carbonyl]amino}ethyl)propanamido)propoxy]phenyl}propanoate (2). It was found that the impurity was present in two rotameric forms at room temperature. The synthesis and NMR characterization of (2) are discussed. PMID:24431238

  5. Analysis of the Effects of Impurities in Silicon. [to determine solar cell efficiency

    NASA Technical Reports Server (NTRS)

    Wohlgemuth, J. H.; Lafky, W. M.; Burkholder, J. H.

    1979-01-01

    A solar cell fabrication and analysis program to determine the effects on the resultant solar cell efficiency of impurities incorporated into silicon is conducted. Flight quality technologies and quality assurance are employed to assure that variations in cell performance are due to the impurities incorporated in the silicon. The type and level of impurity doping in each test lot is given and the mechanism responsible for the degradation of cell performance is identified and correlated to the doped impurities.

  6. Recent advances in trace analysis of pharmaceutical genotoxic impurities.

    PubMed

    Liu, David Q; Sun, Mingjiang; Kord, Alireza S

    2010-04-01

    Genotoxic impurities (GTIs) in pharmaceuticals at trace levels are of increasing concerns to both pharmaceutical industries and regulatory agencies due to their potentials for human carcinogenesis. Determination of these impurities at ppm levels requires highly sensitive analytical methodologies, which poses tremendous challenges on analytical communities in pharmaceutical R&D. Practical guidance with respect to the analytical determination of diverse classes of GTIs is currently lacking in the literature. This article provides an industrial perspective with regard to the analysis of various structural classes of GTIs that are commonly encountered during chemical development. The recent literatures will be reviewed, and several practical approaches for enhancing analyte detectability developed in recent years will be highlighted. As such, this article is organized into the following main sections: (1) trace analysis toolbox including sample introduction, separation, and detection techniques, as well as several 'general' approaches for enhancing detectability; (2) method development: chemical structure and property-based approaches; (3) method validation considerations; and (4) testing and control strategies in process chemistry. The general approaches for enhancing detection sensitivity to be discussed include chemical derivatization, 'matrix deactivation', and 'coordination ion spray-mass spectrometry'. Leveraging the use of these general approaches in method development greatly facilitates the analysis of poorly detectable or unstable/reactive GTIs. It is the authors' intent to provide a contemporary perspective on method development and validation that can guide analytical scientists in the pharmaceutical industries. PMID:20022442

  7. Spectroscopic Analysis of Impurity Precipitates in CdS Films

    SciTech Connect

    Webb, J. D.; Keane, J.; Ribelin, R.; Gedvilas, L.; Swartzlander, A.; Ramanathan, K.; Albin, D. S.; Noufi, R.

    1999-10-31

    Impurities in cadmium sulfide (CdS) films are a concern in the fabrication of copper (indium, gallium) diselenide (CIGS) and cadmium telluride (CdTe) photovoltaic devices. Devices incorporating chemical-bath-deposited (CBD) CdS are comparable in quality to devices incorporating purer CdS films grown using vacuum deposition techniques, despite the higher impurity concentrations typically observed in the CBD CdS films. In this paper, we summarize and review the results of Fourier transform infrared (FTIR), Auger, electron microprobe, and X-ray photoelectron spectroscopic (XPS) analyses of the impurities in CBD CdS films. We show that these impurities differ as a function of substrate type and film deposition conditions. We also show that some of these impurities exist as 10{sup 2} micron-scale precipitates.

  8. Analysis methods for fast impurity ion dynamics data

    SciTech Connect

    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 {mu}s 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.

  9. Theoretical analysis of impurity precipitation in nanopores in crystals. II: Kinetics of impurity cluster growth in pores

    NASA Astrophysics Data System (ADS)

    Lubov, M. N.; Kulikov, D. V.; Trushin, Yu. V.; Kurnosikov, O.

    2013-03-01

    The kinetics of the formation of impurity clusters in subsurface nanopores in crystals is studied theoretically. A physical model of precipitation of the impurity phase in nanopores in a sample with sinks of various types is developed. This model forms the basis for the calculation of the annealing kinetics of copper containing subsurface pores and cobalt impurity atoms. The optimal annealing conditions are determined in which cobalt atoms diffuse predominantly into pores and form impurity clusters in them.

  10. Elemental impurity analysis of mercuric iodide by ICP/MS

    SciTech Connect

    Cross, E.S.; Mroz, E.; Olivares, J.A.

    1994-06-01

    A method has been developed to analyze mercuric iodide (HgI{sub 2}) for elemental contamination using Inductively Coupled Plasma/Mass Spectroscopy (ICP/MS). This paper discusses the ICP/MS method, the effectiveness of purification schemes for removing impurities from HgI{sub 2}, as well as preliminary correlations between HgI{sub 2} detector performance and elemental contamination levels. The purified HgI{sub 2} is grown into a single crystal by physical vapor transport. The crystal are cut into slices and they are fabricated into room temperature radiation detectors and photocells. Crystals that produce good resolution gamma detector do not necessarily make good resolution photocells or x-ray detectors. Many factors other than elemental impurities may contribute to these differences in performance.

  11. Impurities analysis of polycrystalline silicon substrates: Neutronic Activation Analysis (NAA) and Secondary Ion Mass Spectrometry (SIMS)

    NASA Astrophysics Data System (ADS)

    Lounis, A.; Lenouar, K.; Gritly, Y.; Abbad, B.; Azzaz, M.; Taïbi, K.

    2010-01-01

    In this study we have determined the concentration of some impurities such as carbon, iron, copper, titanium, nickel of the flat product (polycrystalline silicon). These impurities generate a yield decrease in the photovoltaic components. The material (polycrystalline silicon) used in this work is manufactured by the Unit of Silicon Technology Development (UDTS Algiers, Algeria). The 80 kg ingot has been cutted into 16 briquettes in order to have plates (flat product) of 100 mm×100 mm dimensions. Each briquette is divided into three parts top (T), middle (M) and bottom (B). For this purpose, the following instrumental analysis techniques have been employed: neutronic analysis (neutronic activation analysis) and secondary ion mass spectrometry (SIMS). Masses of 80 mg are sampled and form of discs 18 mm in diameter, then exposed to a flux of neutron of 2.1012neutron cm-2 s-1 during 15 min. The energetic profile of incidental flux is constituted of fast neutrons (ΦR = 3.1012n.cm-2 s-1; E = 2 Mev), thermal neutrons (ΦTH = 1013n.cm-2 s-1; E = 0.025 ev) and epithermal neutrons (Φepi = 7.1011 n cm-2 s-1; E>4.9 ev), irradiation time 15 mn, after 20 mn of decrement, acquisitions of 300 s are carried out. The results are expressed by disintegration per second which does not exceed the 9000 Bq, 500 Bq and 2600 Bq, respectively for copper, titanium and nickel. It is observed that the impurities concentrations in the medium are higher. The impurities in the bottom of the ingots originate from the crucible. The impurities in the top originate from impurities dissolved in the liquid silicon, which have segregated to the top layer of the ingot and after solidification diffuse. Silicon corresponds to a mixture of three isotopes 28Si, 29Si and 30Si. These elements clearly appear on the mass spectrum (SIMS). The presence of iron and the one of nickel has been noticed.

  12. Quantitative Dopant/Impurity Analysis for ICF Targets

    NASA Astrophysics Data System (ADS)

    Huang, Haibo; Nikroo, Abbas; Stephens, Richard; Eddinger, Samual; Xu, Hongwei; Chen, K. C.; Moreno, Kari

    2008-11-01

    We developed a number of new or improved metrology techniques to measure the spatial distributions of multiple elements in ICF ablator capsules to tight NIF specifications (0.5±0.1 at% Cu, 0.25±0.10 at% Ar, 0.4±0.4 at% O). The elements are either the graded dopants for shock timing, such as Cu in Be, or process-induced impurities, such as Ar and O. Their low concentration, high spatial variation and simultaneous presence make the measurement very difficult. We solved this metrology challenge by combining several techniques: Cu and Ar profiles can be nondestructively measured by operating Contact Radiography (CR) in a differential mode. The result, as well as the O profile, can be checked destructively by a quantitative Energy Dispersive Spectroscopy (EDS) method. Non-spatially resolved methods, such as absorption edge spectroscopy (and to a lesser accuracy, x-ray fluorescence) can calibrate the Ar and Cu measurement in EDS and CR. In addition, oxygen pick-up during mandrel removal can be validated by before-and-after CR and by density change. Use of all these methods gives multiple checks on the reported profiles.

  13. Spatial analysis of impurities on the surface of flange and optical window of the tokamak using laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Maurya, Gulab Singh; Jyotsana, Aradhana; Pathak, Ashok Kumar; Kumar, Ajai; Rai, Awadhesh K.

    2014-05-01

    Laser induced breakdown spectroscopy (LIBS) spectra of optical window and flange of Aditya tokamak have been recorded in the spectral range of 200-500 nm in open atmosphere. For qualitative analysis of these samples, the intensity variation of elemental impurities (Fe, Cr, Ni, Mn, Mo, Cu and C) on the surface of optical window and flange with radial distance has been studied. Depending on thickness of thin films of impurity, four different concentric color rings are observed on the surface of the flange. On moving from reddish brown to indigo color ring, the trends in spectral intensity of these impurities are found in decreasing order. Comparative spectral intensity variation of impurities in both the samples reveals that the impurity deposition on the flange surface is more in comparison to the optical window. Our study demonstrates the capability of LIBS to analyze the spatial distribution of deposited impurities on window and flange samples.

  14. Impurity control and vacuum pumping system design and analysis for next-generation tokamaks

    SciTech Connect

    Haines, J.R.

    1985-01-01

    Impurity control system design and performance studies were performed in support of the Tokamak Fusion Core Experiment (TFCX) preconceptual design. Efforts concentrated on the pumped limiter and vacuum pumping system design configuration, thermal/mechanical and erosion lifetime performance of the limiter protective surface, and helium ash removal performance. Analysis results indicate that the limiter/vacuum pumping system design provides marginally adequate helium ash removal. Difficulties in providing adequate helium ash removal for more compact or higher fusion-power-density devices are addressed. Erosion, primarily by disruption-induced vaporization and/or melting, limits the protective surface lifetime to about one calendar year or only about 60 full power hours of operation. In addition to evaluating impurity control system performance for nominal TFCX conditions, these studies attempt to focus on the key plasma physics and engineering design issues that should be addressed in future research and development programs.

  15. Source Attribution of Cyanides Using Anionic Impurity Profiling, Stable Isotope Ratios, Trace Elemental Analysis and Chemometrics.

    PubMed

    Mirjankar, Nikhil S; Fraga, Carlos G; Carman, April J; Moran, James J

    2016-02-01

    Chemical attribution signatures (CAS) for chemical threat agents (CTAs), such as cyanides, are being investigated to provide an evidentiary link between CTAs and specific sources to support criminal investigations and prosecutions. Herein, stocks of KCN and NaCN were analyzed for trace anions by high performance ion chromatography (HPIC), carbon stable isotope ratio (δ(13)C) by isotope ratio mass spectrometry (IRMS), and trace elements by inductively coupled plasma optical emission spectroscopy (ICP-OES). The collected analytical data were evaluated using hierarchical cluster analysis (HCA), Fisher-ratio (F-ratio), interval partial least-squares (iPLS), genetic algorithm-based partial least-squares (GAPLS), partial least-squares discriminant analysis (PLSDA), K nearest neighbors (KNN), and support vector machines discriminant analysis (SVMDA). HCA of anion impurity profiles from multiple cyanide stocks from six reported countries of origin resulted in cyanide samples clustering into three groups, independent of the associated alkali metal (K or Na). The three groups were independently corroborated by HCA of cyanide elemental profiles and corresponded to countries each having one known solid cyanide factory: Czech Republic, Germany, and United States. Carbon stable isotope measurements resulted in two clusters: Germany and United States (the single Czech stock grouped with United States stocks). Classification errors for two validation studies using anion impurity profiles collected over five years on different instruments were as low as zero for KNN and SVMDA, demonstrating the excellent reliability associated with using anion impurities for matching a cyanide sample to its factory using our current cyanide stocks. Variable selection methods reduced errors for those classification methods having errors greater than zero; iPLS-forward selection and F-ratio typically provided the lowest errors. Finally, using anion profiles to classify cyanides to a specific stock

  16. Neutron activation analysis by standard addition and solvent extraction: Determination of impurities in aluminium.

    PubMed

    Alian, A; Haggag, A

    1967-09-01

    A separation scheme based on selective extraction in conjunction with the standard addition technique has been developed for the determination of impurities in aluminium by neutron activation. Preliminary investigations have been carried out on the extractability of Sc, Co, Hf, Fe, Sn, Cd, Zn, Ag, Cr, Ce, Cs and Rb by TDA and TBP from acidic media. The best conditions are predicted for the separation of these elements into fractions suitable for analysis by gamma-ray spectrometry. Recovery values of approximately 90% were obtained for all the elements. PMID:18960206

  17. Secondary ionization mass spectrometric analysis of impurity element isotope ratios in nuclear reactor materials

    NASA Astrophysics Data System (ADS)

    Gerlach, D. C.; Cliff, J. B.; Hurley, D. E.; Reid, B. D.; Little, W. W.; Meriwether, G. H.; Wickham, A. J.; Simmons, T. A.

    2006-07-01

    During reactor operations and fuel burn up, some isotopic abundances change due to nuclear reactions and provide sensitive indicators of neutron fluence and fuel burnup. Secondary ion mass spectrometry (SIMS) analysis has been used to measure isotope ratios of selected impurity elements in irradiated nuclear reactor graphite. Direct SIMS measurements were made in graphite samples, following shaping and surface cleaning. Models predicting local fuel burnup based on isotopic measurements of B and Li isotopes by SIMS agreed well with U and Pu isotopic measurements obtained by thermal ionization mass spectrometry (TIMS).

  18. A quasi-linear analysis of the impurity effect on turbulent momentum transport and residual stress

    SciTech Connect

    Ko, S. H. Jhang, Hogun; Singh, R.

    2015-08-15

    We study the impact of impurities on turbulence driven intrinsic rotation (via residual stress) in the context of the quasi-linear theory. A two-fluid formulation for main and impurity ions is employed to study ion temperature gradient modes in sheared slab geometry modified by the presence of impurities. An effective form of the parallel Reynolds stress is derived in the center of mass frame of a coupled main ion-impurity system. Analyses show that the contents and the radial profile of impurities have a strong influence on the residual stress. In particular, an impurity profile aligned with that of main ions is shown to cause a considerable reduction of the residual stress, which may lead to the reduction of turbulence driven intrinsic rotation.

  19. Batch methods for enriching trace impurities in hydrogen gas for their further analysis

    DOEpatents

    Ahmed, Shabbir; Lee, Sheldon H.D.; Kumar, Romesh; Papdias, Dionissios D.

    2014-07-15

    Provided herein are batch methods and devices for enriching trace quantities of impurities in gaseous mixtures, such as hydrogen fuel. The methods and devices rely on concentrating impurities using hydrogen transport membranes wherein the time period for concentrating the sample is calculated on the basis of optimized membrane characteristics, comprising its thickness and permeance, with optimization of temperature, and wherein the enrichment of trace impurities is proportional to the pressure ratio P.sub.hi/P.sub.lo and the volume ratio V.sub.1/V.sub.2, with following detection of the impurities using commonly-available detection methods.

  20. Development and validation of a reversed phase liquid chromatographic method for analysis of oxytetracycline and related impurities.

    PubMed

    Kahsay, Getu; Shraim, Fairouz; Villatte, Philippe; Rotger, Jacques; Cassus-Coussère, Céline; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

    2013-03-01

    A simple, robust and fast high-performance liquid chromatographic method is described for the analysis of oxytetracycline and its related impurities. The principal peak and impurities are all baseline separated in 20 min using an Inertsil C₈ (150 mm × 4.6 mm, 5 μm) column kept at 50 °C. The mobile phase consists of a gradient mixture of mobile phases A (0.05% trifluoroacetic acid in water) and B (acetonitrile-methanol-tetrahydrofuran, 80:15:5, v/v/v) pumped at a flow rate of 1.3 ml/min. UV detection was performed at 254 nm. The developed method was validated for its robustness, sensitivity, precision and linearity in the range from limit of quantification (LOQ) to 120%. The limits of detection (LOD) and LOQ were found to be 0.08 μg/ml and 0.32 μg/ml, respectively. This method allows the separation of oxytetracycline from all known and 5 unknown impurities, which is better than previously reported in the literature. Moreover, the simple mobile phase composition devoid of non-volatile buffers made the method suitable to interface with mass spectrometry for further characterization of unknown impurities. The developed method has been applied for determination of related substances in oxytetracycline bulk samples available from four manufacturers. The validation results demonstrate that the method is reliable for quantification of oxytetracycline and its impurities. PMID:23277151

  1. Genetic analysis of quartz from pegmatites of the Mama-Chuya mica belt based on distribuition of isomorphic impurities, Russia

    NASA Astrophysics Data System (ADS)

    Rakov, L. T.; Tkachev, A. V.; Sakhnov, A. A.

    2013-02-01

    The effect of the formation conditions of pegmatites in the Mama-Chuya mica belt on the distribution of isomorphic Al, Ti, and Ge impurities in quartz detected by electron paramagnetic resonance (EPR) has been estimated using the isogen method, which takes into account the relationship between this distribution and geological time. It has been revealed that each of the studied types of pegmatite veins is described by special isogens that reflect interrelations between concentrations of various isomorphic impurities. The typification of veins, enrichment of parental melt in water, and other factors affect the isogens. New potentialities of the isogen method for genetic analysis of quartz have been established.

  2. Improved quality control of [18F]FDG by HPLC with UV detection.

    PubMed

    Nakao, Ryuji; Ito, Takehito; Yamaguchi, Masatoshi; Suzuki, Kazutoshi

    2005-11-01

    A conventional high-performance liquid chromatographic (HPLC) method for the analysis of 2-fluoro-2-deoxy-d-glucose (FDG) and 2-deoxy-2-chloro-d-glucose (ClDG) in [18F]FDG preparations is described. This method was based on a postcolumn derivatization with 2-cyanoacetamide (2-CA) and UV detection. FDG and ClDG were separated on a normal-phase column using acetonitrile/water as the mobile phase. The eluate was mixed with 2-CA in sodium borate buffer solution at the outlet of a PTFE coil (10 m x 0.5 mm id) from the column, and the reaction was carried out at 100 degrees C during the passage through the coil. The UV absorbance of the resultant product was monitored at 276 nm. Under optimum conditions, the detection limits [signal-to-noise (S/N) ratio=3] for FDG and ClDG were 0.31 and 0.17 microg/ml for a 20-microl injection volume, respectively, and the linearity ranges were 0.5-100 microg/ml for both compounds. The intra- and interday reproducibilities were better than 2.2% [relative standard deviation (R.S.D.)]. This HPLC separation procedure is also useful for determining the radiochemical purity of [18F]FDG preparations since it allows the analysis of 2-[18F]fluoro-1,3,4,6-tetra-O-acetyl-d-glucose ([18F]TAG), partially hydrolyzed [18F]TAG and [18F]F-. This method can be used at many positron emission tomography (PET) facilities since it does not require an expensive, sophisticated electrochemical detector. PMID:16253817

  3. Spectroscopic analysis of low Z impurities in the Tandem Mirror Experiment-upgrade

    SciTech Connect

    Yu, T.L.

    1986-09-01

    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 normal incidence spectrograph that measures the time histories of several impurity emission lines (300 to 1800 A) in a single shot; radial scans can be obtained on a shot-by-shot basis. The other instrument is a monochromator that measures time-resolved radial profiles of a given impurity emission line in a single shot. The common intrinsic impurities measured in TMX-U are C,N,O and Ti. It has been shown that large fractions of the oxygen and nitrogen in the plasma are associated with the neutral beams while the main source of carbon is the plasma wall. 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 blow discharge cleaning and titanium gettering. No significant accumulation of impurity ions in the thermal barrier region has been observed.

  4. Analysis of deposited impurity material on the surface of the optical window of the Tokamak using LIBS

    NASA Astrophysics Data System (ADS)

    Singh Maurya, Gulab; Jyotsana, Aradhana; Kumar, Rohit; Kumar, Ajai; Rai, A. K.

    2014-07-01

    The emission spectra emitted from the laser-induced plasma of the optical window of Aditya Tokamak have been studied to identify the eroded materials deposited on its surface. Different layers of the window, such as the impurity deposited layer, antireflection coating and main matrix of the window material, have been identified. Laser-induced breakdown spectroscopy (LIBS) spectra of the impurity layer (first layer) shows the presence of spectral lines of Fe, Cr, Ni, Mn, Mo, Cu, C and O most of which are the components of stainless steel (SS316L) used for the fabrication of the Tokamak. LIBS spectra of the antireflection coating layer (second layer) show the spectral signature of Ca and Mg, whereas in the inner layer (last layer), the spectral lines of Al, Si and B are present. The concentrations of the impurities estimated by CF-LIBS are closely related to the constituents (major and minor) of the SS316L. Principal component analysis using LIBS data was performed to differentiate the different layers (impurity, antireflection coating and main matrix) of the window. The result of the present study demonstrates the capability of LIBS as an in-situ monitoring tool for detection and quantification of elements present in the different layers of the optical window of the Tokamak.

  5. Process development and impurities analysis for the bottom antireflective coating material

    NASA Astrophysics Data System (ADS)

    Ko, Fu-Hsiang; Chen, Hsuen-Li; Huang, Tiao-Yuan; Cheng, Hsu-Chun; Ko, Chu-Jung; Chu, Tieh-Chi

    2001-08-01

    The optical behavior of semiconductor bottom antireflective coating (BARC) material was investigated by both the measurement and simulation methods. The effects of spin- coating rate, interface reflection, BARC layer thickness and photoresist layer thickness were studied. Our results indicated that the 62.5 nm of BARC layer had strong effect on suppressing the light reflection of wavelength of 248 nm form the wafer surface, irrespective of the photoresist layer thickness. Based on the gravimetric method, a high throughput and one-step microwave digestion procedure was developed for the BARC materials. The digestion efficiency increased with the digestion duration and the temperature. By following the established one-step microwave digestion method and inductively coupled plasma mass spectrometry determination, the detection limits obtained for Cr, Ni, Cu, An and Pb were in 0.1 to 1.11 ppb levels. The spike recoveries of the metallic impurities were in the range 86- 102% for the BARC materials. The analytical results of the BARC samples were found to be in reasonably good agreement with our previous method, and the analytical throughput can achieve up to 20 samples per hour for the analysis of 5 elements.

  6. Reverse process of usual optical analysis of boson-exchange superconductors: impurity effects on s- and d-wave superconductors

    NASA Astrophysics Data System (ADS)

    Hwang, Jungseek

    2015-03-01

    We performed a reverse process of the usual optical data analysis of boson-exchange superconductors. We calculated the optical self-energy from two (MMP and MMP+peak) input model electron-boson spectral density functions using Allen's formula for one normal and two (s- and d-wave) superconducting cases. We obtained the optical constants including the optical conductivity and the dynamic dielectric function from the optical self-energy using an extended Drude model, and finally calculated the reflectance spectrum. Furthermore, to investigate impurity effects on optical quantities we added various levels of impurities (from the clean to the dirty limit) in the optical self-energy and performed the same reverse process to obtain the optical conductivity, the dielectric function, and reflectance. From these optical constants obtained from the reverse process we extracted the impurity-dependent superfluid densities for two superconducting cases using two independent methods (the Ferrel-Glover-Tinkham sum rule and the extrapolation to zero frequency of -ɛ1(ω)ω2) we found that a certain level of impurities is necessary to get a good agreement on results obtained by the two methods. We observed that impurities give similar effects on various optical constants of s- and d-wave superconductors; the greater the impurities the more distinct the gap feature and the lower the superfluid density. However, the s-wave superconductor gives the superconducting gap feature more clearly than the d-wave superconductor because in the d-wave superconductors the optical quantities are averaged over the anisotropic Fermi surface. Our results supply helpful information to see how characteristic features of the electron-boson spectral function and the s- and d-wave superconducting gaps appear in various optical constants including raw reflectance spectrum. Our study may help with a thorough understanding of the usual optical analysis process. Further systematic study of experimental data

  7. Structural Analysis and Quantitative Determination of Clevidipine Butyrate Impurities Using an Advanced RP-HPLC Method.

    PubMed

    Zhou, Yuxia; Zhou, Fan; Yan, Fei; Yang, Feng; Yao, Yuxian; Zou, Qiaogen

    2016-03-01

    Eleven potential impurities, including process-related compounds and degradation products, have been analyzed by comprehensive studies on the manufacturing process of clevidipine butyrate. Possible formation mechanisms could also be devised. MS and NMR techniques have been used for the structural characterization of three previously unreported impurities (Imp-3, Imp-5 and Imp-11). To separate and quantify the potential impurities in a simultaneous fashion, an efficient and advanced RP-HPLC method has been developed. In doing so, four major degradation products (Imp-2, Imp-4, Imp-8 and Imp-10) can be observed under varying stress conditions. This analytical method has been validated according to ICH guidelines with respect to specificity, accuracy, linearity, robustness and stability. The method described has been demonstrated to be applicable in routine quality control processes and stability evaluation studies of clevidipine butyrate. PMID:26489435

  8. Effect of weak impurities on electronic properties of graphene: Functional renormalization-group analysis

    NASA Astrophysics Data System (ADS)

    Katanin, A.

    2013-12-01

    We consider an effect of weak impurities on the electronic properties of graphene within the functional renormalization-group approach. The energy dependences of the electronic self-energy and density of states near the neutrality point are discussed. Depending on the symmetry of the impurities, the electronic damping Γ and density of states ρ can deviate substantially from those given by the self-consistent Born approximation. We investigate the crossover from the results of the self-consistent Born approximation, which are valid far from the neutrality point to the strong-coupling (diffusive) regime near the neutrality point. For impurities, which are diagonal in both valley and sublattice indices, we obtain a finite density of states at the Fermi level with values which are much bigger than the result of the self-consistent Born approximation.

  9. Thermodynamic Analysis Of Pure And Impurity Doped Pentaerythritol Tetranitrate Crystals Grown At Room Temperature

    SciTech Connect

    Pitchimani, R; Zheng, W; Simon, S; Hope-Weeks, L; Burnham, A K; Weeks, B L

    2006-05-25

    Pentaerythritol tetranitrate (PETN) powders are used to initiate other explosives. During long-term storage, changes in powder properties can cause changes in the initiation performance. Changes in the morphology and surface area of aging powders are observed due to sublimation and growth of PETN crystals through coarsening mechanisms, (e.g. Ostwald ripening, sintering, etc.). In order to alleviate the sublimation of PETN crystals under service conditions, stabilization methods such as thermal cycling and doping with certain impurities during or after the crystallization of PETN have been proposed. In this report we present our work on the effect of impurities on the morphology and activation energy of the PETN crystals. The pure and impurity doped crystals of PETN were grown from supersaturated acetone solution by solvent evaporation technique at room temperature. The difference in the morphology of the impurity-doped PETN crystal compared to pure crystal was examined by optical microscopy. The changes in the activation energies and the evaporation rates are determined by thermogravimetric (TGA) analyses. Our activation energies of evaporation agree with earlier reported enthalpies of vaporization. The morphology and activation energy of PETN crystals doped with Ca, Na, and Fe cations are similar to that for pure PETN crystal, whereas the Zn-ion-doped PETN crystals have different morphology and decreased activation energy.

  10. Analysis of pharmaceutical impurities using multi-heartcutting 2D LC coupled with UV-charged aerosol MS detection.

    PubMed

    Zhang, Kelly; Li, Yi; Tsang, Midco; Chetwyn, Nik P

    2013-09-01

    To overcome challenges in HPLC impurity analysis of pharmaceuticals, we developed an automated online multi-heartcutting 2D HPLC system with hyphenated UV-charged aerosol MS detection. The first dimension has a primary column and the second dimension has six orthogonal columns to enhance flexibility and selectivity. The two dimensions were interfaced by a pair of switching valves equipped with six trapping loops that allow multi-heartcutting of peaks of interest in the first dimension and also allow "peak parking." The hyphenated UV-charged aerosol MS detection provides comprehensive detection for compounds with and without UV chromophores, organics, and inorganics. It also provides structural information for impurity identification. A hidden degradation product that co-eluted with the drug main peak was revealed by RP × RP separation and thus enabled the stability-indicating method development. A poorly retained polar component with no UV chromophores was analyzed by RP × hydrophilic interaction liquid chromatography separation with charged aerosol detection. Furthermore, using this system, the structures of low-level impurities separated by a method using nonvolatile phosphate buffer were identified and tracked by MS in the second dimension. PMID:23821312

  11. Chemical Analysis of Impurity Boron Atoms in Diamond Using Soft X-ray Emission Spectroscopy

    SciTech Connect

    Muramatsu, Yasuji; Iihara, Junji; Takebe, Toshihiko; Denlinger, Jonathan D.

    2008-03-29

    To analyze the local structure and/or chemical states of boron atoms in boron-doped diamond, which can be synthesized by the microwave plasma-assisted chemical vapor deposition method (CVD-B-diamond) and the temperature gradient method at high pressure and high temperature (HPT-B-diamond), we measured the soft X-ray emission spectra in the CK and BK regions of B-diamonds using synchrotron radiation at the Advanced Light Source (ALS). X-ray spectral analyses using the fingerprint method and molecular orbital calculations confirm that boron atoms in CVD-B-diamond substitute for carbon atoms in the diamond lattice to form covalent B-C bonds, while boron atoms in HPT-B-diamond react with the impurity nitrogen atoms to form hexagonal boron nitride. This suggests that the high purity diamond without nitrogen impurities is necessary to synthesize p-type B-diamond semiconductors.

  12. Adsorption site analysis of impurity embedded single-walled carbon nanotube bundles

    USGS Publications Warehouse

    Agnihotri, S.; Mota, J.P.B.; Rostam-Abadi, M.; Rood, M.J.

    2006-01-01

    Bundle morphology and adsorptive contributions from nanotubes and impurities are studied both experimentally and by simulation using a computer-aided methodology, which employs a small physisorbed probe molecule to explore the porosity of nanotube samples. Grand canonical Monte Carlo simulation of nitrogen adsorption on localized sites of a bundle is carried out to predict adsorption in its accessible internal pore volume and on its external surface as a function of tube diameter. External adsorption is split into the contributions from the clean surface of the outermost nanotubes of the bundle and from the surface of the impurities. The site-specific isotherms are then combined into a global isotherm for a given sample using knowledge of its tube-diameter distribution obtained by Raman spectroscopy. The structural parameters of the sample, such as the fraction of open-ended nanotubes and the contributions from impurities and nanotube bundles to total external surface area, are determined by fitting the experimental nitrogen adsorption data to the simulated isotherm. The degree of closure between experimental and calculated adsorption isotherms for samples manufactured by two different methods, to provide different nanotube morphology and contamination level, further strengthens the validity and resulting interpretations based on the proposed approach. The average number of nanotubes per bundle and average bundle size, within a sample, are also quantified. The proposed method allows for extrapolation of adsorption properties to conditions where the purification process is 100% effective at removing all impurities and opening access to all intrabundle adsorption sites. ?? 2006 Elsevier Ltd. All rights reserved.

  13. Impurity gettering

    SciTech Connect

    Picraux, S.T.

    1995-06-01

    Transition metal impurities are well known to cause detrimental effects when present in the active regions of Si devices. Their presence degrades minority carrier lifetime, provides recombination-generation centers, increases junction leakage current and reduces gate oxide integrity. Thus, gettering processes are used to reduce the available metal impurities from the active region of microelectronic circuits. Gettering processes are usually divided into intrinsic (or internal) and extrinsic (or external) categories. Intrinsic refers to processing the Si wafer in a way to make available internal gettering sites, whereas extrinsic implies externally introduced gettering sites. Special concerns have been raised for intrinsic gettering. Not only will the formation of the precipitated oxide and denuded zone be difficult to achieve with the lower thermal budgets, but another inherent limit may set in. In this or any process which relies on the precipitation of metal silicides the impurity concentration can only be reduced as low as the solid solubility limit. However, the solubilities of transition metals relative to silicide formation are typically found to be {approx_gt}10{sup 12}/cm{sup 3} at temperatures of 800 C and above, and thus inadequate to getter to the needed concentration levels. It is thus anticipated that future microelectronic device processing will require one or more of the following advances in gettering technology: (1) new and more effective gettering mechanisms; (2) quantitative models of gettering to allow process optimization at low process thermal budgets and metal impurity concentrations, and/or (3) development of front side gettering methods to allow for more efficient gettering close to device regions. These trend-driven needs provide a driving force for qualitatively new approaches to gettering and provide possible new opportunities for the use of ion implantation in microelectronics processing.

  14. Analysis of trace impurities in semiconductor gas via cavity-enhanced direct frequency comb spectroscopy

    NASA Astrophysics Data System (ADS)

    Cossel, K. C.; Adler, F.; Bertness, K. A.; Thorpe, M. J.; Feng, J.; Raynor, M. W.; Ye, J.

    2010-09-01

    Cavity-enhanced direct frequency comb spectroscopy (CE-DFCS) has demonstrated powerful potential for trace-gas detection based on its unique combination of high bandwidth, rapid data acquisition, high sensitivity, and high resolution, which is unavailable with conventional systems. However, previous demonstrations have been limited to proof-of-principle experiments or studies of fundamental laboratory science. Here, we present the development of CE-DFCS towards an industrial application—measuring impurities in arsine, an important process gas used in III-V semiconductor compound manufacturing. A strongly absorbing background gas with an extremely complex, congested, and broadband spectrum renders trace detection exceptionally difficult, but the capabilities of CE-DFCS overcome this challenge and make it possible to identify and quantify multiple spectral lines associated with water impurities. Further, frequency combs allow easy access to new spectral regions via efficient nonlinear optical processes. Here, we demonstrate detection of multiple potential impurities across 1.75-1.95 μm (5710-5130 cm-1), with a single-channel detection sensitivity (simultaneously over 2000 channels) of ˜4×10-8 cm-1 Hz-1/2 in nitrogen and, specifically, an absorption sensitivity of ˜4×10-7 cm-1 Hz-1/2 for trace water doped in arsine.

  15. Analysis of trace impurities in neon by a customized gas chromatography.

    PubMed

    Yin, Min Kyo; Lim, Jeong Sik; Moon, Dong Min; Lee, Gae Ho; Lee, Jeongsoon

    2016-09-01

    Excimer lasers, widely used in the semiconductor industry, are crucial for analyzing the purity of premix laser gases for the purpose of controlling stable laser output power. In this study, we designed a system for analyzing impurities in pure neon (Ne) base gas by customized GC. Impurities in pure neon (H2 and He), which cannot be analyzed at the sub-μmol/mol level using commercial GC detectors, were analyzed by a customized pulsed-discharge Ne ionization detector (PDNeD) and a pressurized injection thermal conductivity detector using Ne as the carrier gas (Pres. Inj. Ne-TCD). From the results, trace species in Ne were identified with the following detection limits: H2, 0.378μmol/mol; O2, 0.119μmol/mol; CH4, 0.880μmol/mol; CO, 0.263μmol/mol; CO2, 0.162μmol/mol (PDNeD); and He, 0.190μmol/mol (Pres. Inj. Ne-TCD). This PDNeD and pressurized injection Ne-TCD technique thus developed permit the quantification of trace impurities present in high-purity Ne. PMID:27527880

  16. Matrix deactivation: A general approach to improve stability of unstable and reactive pharmaceutical genotoxic impurities for trace analysis.

    PubMed

    Sun, Mingjiang; Bai, Lin; Terfloth, Gerald J; Liu, David Q; Kord, Alireza S

    2010-05-01

    Trace analysis of unstable and reactive pharmaceutical genotoxic impurities (GTIs) is a challenging task in pharmaceutical analysis. Many method issues such as insufficient sensitivity, poor precision, and unusual (too high/low) spiking recovery are often directly related to analytes' instability. We report herein a matrix deactivation approach that chemically stabilizes these analytes for analytical method development. In contrast to the conventional chemical derivatization approach where the analytes are transformed into stable detectable species, the matrix deactivation approach chemically deactivates the hypothetical reactive species in the sample matrix. The matrix deactivation approach was developed on the premise that the instability of certain analytes at trace level is caused by reactions between the analytes and low level reactive species in the sample matrix. Thus, quenching the reactivity of the reactive species would be a key to stabilizing the unstable and reactive analytes. For example, electrophilic alkylators could be destabilized by nucleophiles or bases through either nucleophilic substitution or elimination reactions. One way to mask those reactive species is via protonation by adding acids to the diluent. Alternatively, one can use nucleophile scavengers to deplete reactive unknown species in the sample matrix completely, in analogy to the use of antioxidants and metal chelators to prevent oxidation in the analysis of compounds liable to oxidation. This paper reports the application of the matrix deactivation to the analyses of unstable and reactive pharmaceutical genotoxic impurities. Some of the methods have been used to support development of manufacturing processes for drug substances and a recent regulatory filing. PMID:20036478

  17. Characterization of the cell growth analysis for detection of immortal cellular impurities in human mesenchymal stem cells.

    PubMed

    Kono, Ken; Takada, Nozomi; Yasuda, Satoshi; Sawada, Rumi; Niimi, Shingo; Matsuyama, Akifumi; Sato, Yoji

    2015-03-01

    The analysis of in vitro cell senescence/growth after serial passaging can be one of ways to show the absence of immortalized cells, which are frequently tumorigenic, in human cell-processed therapeutic products (hCTPs). However, the performance of the cell growth analysis for detection of the immortalized cellular impurities has never been evaluated. In the present study, we examined the growth rates of human mesenchymal stem cells (hMSCs, passage 5 (P = 5)) contaminated with various doses of HeLa cells, and compared with that of hMSCs alone. The growth rates of the contaminated hMSCs were comparable to that of hMSCs alone at P = 5, but significantly increased at P = 6 (0.1% and 0.01% HeLa) or P = 7 (0.001% HeLa) within 30 days. These findings suggest that the cell growth analysis is a simple and sensitive method to detect immortalized cellular impurities in hCTPs derived from human somatic cells. PMID:25523786

  18. Proceedings of the workshop on applications of synchrotron radiation to trace impurity analysis for advanced silicon processing

    SciTech Connect

    Laderman, S; Pianetta, P

    1993-03-01

    Wafer surface trace impurity analysis is essential for development of competitive Si circuit technologies. Today's grazing incidence x-ray fluorescence techniques with rotating anodes fall short of requirements for the future. Hewlett Packard/Toshiba experiments indicate that with second generation synchrotron sources such as SSRL, the techniques can be extended sufficiently to meet important needs of the leading edge Si circuit industry through nearly all of the 1990's. This workshop was held to identify people interested in use of synchrotron radiation-based methods and to document needs and concerns for further development. Viewgraphs are included for the following presentations: microcontamination needs in silicon technology (M. Liehr), analytical methods for wafer surface contamination (A. Schimazaki), trace impurity analysis of liquid drops using synchrotron radiation (D. Wherry), TRXRF using synchrotron sources (S. Laderman), potential role of synchrotron radiation TRXRF in Si process R D (M. Scott), potenital development of synchrotron radiation facilities (S. Brennan), and identification of goals, needs and concerns (M. Garner).

  19. Statistical analysis of variations in impurity ion heating at reconnection events in the Madison Symmetric Torus

    SciTech Connect

    Cartolano, M. S.; Craig, D.; Den Hartog, D. J.; Kumar, S. T. A.; Nornberg, M. D.

    2014-01-15

    The connection between impurity ion heating and other physical processes in the plasma is evaluated by studying variations in the amount of ion heating at reconnection events in the Madison Symmetric Torus (MST). Correlation of the change in ion temperature with individual tearing mode amplitudes indicates that the edge-resonant modes are better predictors for the amount of global ion heating than the core-resonant modes. There is also a strong correlation between ion heating and current profile relaxation. Simultaneous measurements of the ion temperature at different toroidal locations reveal, for the first time, a toroidal asymmetry to the ion heating in MST. These results present challenges for existing heating theories and suggest a stronger connection between edge-resonant tearing modes, current profile relaxation, and ion heating than has been previously thought.

  20. Thermal Analysis of Surrogate Simulated Molten Salts with Metal Chloride Impurities for Electrorefining Used Nuclear Fuel

    SciTech Connect

    Toni Y. Gutknecht; Guy L. Fredrickson; Vivek Utgikar

    2012-04-01

    This project is a fundamental study to measure thermal properties (liquidus, solidus, phase transformation, and enthalpy) of molten salt systems of interest to electrorefining operations, which are used in both the fuel cycle research & development mission and the spent fuel treatment mission of the Department of Energy. During electrorefining operations the electrolyte accumulates elements more active than uranium (transuranics, fission products and bond sodium). The accumulation needs to be closely monitored because the thermal properties of the electrolyte will change as the concentration of the impurities increases. During electrorefining (processing techniques used at the Idaho National Laboratory to separate uranium from spent nuclear fuel) it is important for the electrolyte to remain in a homogeneous liquid phase for operational safeguard and criticality reasons. The phase stability of molten salts in an electrorefiner may be adversely affected by the buildup of fission products in the electrolyte. Potential situations that need to be avoided are: (i) build up of fissile elements in the salt approaching the criticality limits specified for the vessel (ii) freezing of the salts due to change in the liquidus temperature and (iii) phase separation (non-homogenous solution) of elements. The stability (and homogeneity) of the phases can potentially be monitored through the thermal characterization of the salts, which can be a function of impurity concentration. This work describes the experimental results of typical salts compositions, consisting of chlorides of strontium, samarium, praseodymium, lanthanum, barium, cerium, cesium, neodymium, sodium and gadolinium (as a surrogate for both uranium and plutonium), used in the processing of used nuclear fuels. Differential scanning calorimetry was used to analyze numerous salt samples providing results on the thermal properties. The property of most interest to pyroprocessing is the liquidus temperature. It was

  1. Development and validation of a hydrophilic interaction chromatography method coupled with a charged aerosol detector for quantitative analysis of nonchromophoric α-hydroxyamines, organic impurities of metoprolol.

    PubMed

    Xu, Qun; Tan, Shane; Petrova, Katya

    2016-01-25

    The European Pharmacopeia (EP) metoprolol impurities M and N are polar, nonchromophoric α-hydroxyamines, which are poorly retained in a conventional reversed-phase chromatographic system and are invisible for UV detection. Impurities M and N are currently analyzed by TLC methods in the EP as specified impurities and in the United States Pharmacopeia-National Formulary (USP-NF) as unspecified impurities. In order to modernize the USP monographs of metoprolol drug substances and related drug products, a hydrophilic interaction chromatography (HILIC) method coupled with a charged aerosol detector (CAD) was explored for the analysis of the two impurities. A comprehensive column screening that covers a variety of HILIC stationary phases (underivatized silica, amide, diol, amino, zwitterionic, polysuccinimide, cyclodextrin, and mixed-mode) and optimization of HPLC conditions led to the identification of a Halo Penta HILIC column (4.6 × 150 mm, 5 μm) and a mobile phase comprising 85% acetonitrile and 15% ammonium formate buffer (100 mM, pH 3.2). Efficient separations of metoprolol, succinic acid, and EP metoprolol impurities M and N were achieved within a short time frame (<8 min). The HILIC-CAD method was subsequently validated per USP validation guidelines with respect to specificity, robustness, linearity, accuracy, and precision, and could be incorporated into the current USP-NF monographs to replace the outdated TLC methods. Furthermore, the developed method was successfully applied to determine organic impurities in metoprolol drug substance (metoprolol succinate) and drug products (metoprolol tartrate injection and metoprolol succinate extended release tablets). PMID:26580821

  2. Light absorption from particulate impurities in snow and ice determined by spectrophotometric analysis of filters

    SciTech Connect

    Grenfell, Thomas C.; Doherty, Sarah J.; Clarke, Antony D.; Warren, Stephen G.

    2011-05-10

    Light absorption by particulate impurities in snow and ice can affect the surface albedo and is important for the climate. The absorption properties of these particles can be determined by collecting and melting snow samples and extracting the particulate material by filtration of the meltwater. This paper describes the optical design and testing of a new instrument to measure the absorption spectrum from 400 to 750 nm wavelength of the particles collected on filters using an ''integrating-sandwich'' configuration. The measured absorption is shown to be unaffected by scattering of light from the deposited particulates. A set of calibration standards is used to derive an upper limit for the concentration of black carbon (BC) in the snow. The wavelength dependence of the absorption spectra from 450 to 600 nm is used to calculate an absorption Angstrom exponent for the aerosol. This exponent is used to estimate the actual BC concentration in the snow samples as well as the relative contributions of BC and non-BC constituents to the absorption of solar radiation integrated over the wavelength band 300 to 750 nm.

  3. Light absorption from particulate impurities in snow and ice determined by spectrophotometric analysis of filters.

    PubMed

    Grenfell, Thomas C; Doherty, Sarah J; Clarke, Antony D; Warren, Stephen G

    2011-05-10

    Light absorption by particulate impurities in snow and ice can affect the surface albedo and is important for the climate. The absorption properties of these particles can be determined by collecting and melting snow samples and extracting the particulate material by filtration of the meltwater. This paper describes the optical design and testing of a new instrument to measure the absorption spectrum from 400 to 750 nm wavelength of the particles collected on filters using an "integrating-sandwich" configuration. The measured absorption is shown to be unaffected by scattering of light from the deposited particulates. A set of calibration standards is used to derive an upper limit for the concentration of black carbon (BC) in the snow. The wavelength dependence of the absorption spectra from 450 to 600 nm is used to calculate an absorption Ångstrom exponent for the aerosol. This exponent is used to estimate the actual BC concentration in the snow samples as well as the relative contributions of BC and non-BC constituents to the absorption of solar radiation integrated over the wavelength band 300 to 750 nm. PMID:21556105

  4. Spectral Absorption By Particulate Impurities in Snow Determined By Photometric Analysis Of Filters

    NASA Astrophysics Data System (ADS)

    Grenfell, T. C.; Doherty, S. J.; Clarke, A. D.

    2009-12-01

    Our work is motivated by the 1983-84 survey by Clarke and Noone (Atmos. Environ., 1985) of soot in Arctic snow. Our objective is to resurvey the original area they covered and to extend the observations around the entire Arctic Basin under the auspices of the IPY program. We use the filtering and integrating sandwich techniques developed by Clarke and Noone to process the snow samples. Among the advantages of this method are that (a) it provides a direct measure of light absorption and the result is closely related to the actual absorption of sunlight in the snow or ice, (b) processing and filtering of the snow samples can be carried out in remote locations and (c) it is not necessary to transport large quantities of snow back to our home laboratory. Here we describe the construction, calibration, and some applications of an integrating sphere spectrophotometer system designed to take advantage of recent advances in instrumentation to improve the accuracy of measurements of absorption by particulate impurities collected on nuclepore filters used in our survey. Filter loading in terms of effective black carbon (BC) amount is determined together with the ratio of non-BC to BC concentrations using a set of reference filters with known loadings of Monarch 71 BC prepared by A. D. Clarke. The new spectrophotometer system has (a) system stability of approximately 0.5%; (b) precision relative to ADC standards of 3-4% for filter loadings greater than about 0.5 microgm Carbon/cm2. (c) We can distinguish BC from non-BC from relative spectral shapes of the energy absorption curves with an accuracy that depends on our knowledge of the spectral absorption curves of the non-BC components; and (d) by-eye estimates are consistent with spectrophotometric results. The major outstanding uncertainty is the appropriate value to use for the mass absorption efficiency for BC.

  5. Comparison of Impurities in Charcoal Sorbents Found by Neutron Activation Analysis

    SciTech Connect

    Doll, Charles G.; Finn, Erin C.; Cantaloub, Michael G.; Greenwood, Lawrence R.; Kephart, Jeremy; Kephart, Rosara F.

    2013-01-01

    Abstract: Neutron activation of gas samples in a reactor often requires a medium to retain sufficient amounts of the gas for analysis. Charcoal is commonly used to adsorb gas and hold it for activation; however, the amount of activated sodium in the charcoal after irradiation swamps most signals of interest. Neutron activation analysis (NAA) was performed on several commonly available charcoal samples in an effort to determine the activation background. The results for several elements, including the dominant sodium element, are reported. It was found that ECN charcoal had the lowest elemental background, containing sodium at 2.65 ± 0.05 ppm, as well as trace levels of copper and tungsten.

  6. Impurity-induced divertor plasma oscillations

    DOE PAGESBeta

    Smirnov, R. D.; Kukushkin, A. S.; Krasheninnikov, S. I.; Pigarov, A. Yu.; Rognlien, T. D.

    2016-01-07

    Two different oscillatory plasma regimes induced by seeding the plasma with high- and low-Z impurities are found for ITER-like divertor plasmas, using computer modeling with the DUSTT/UEDGE and SOLPS4.3 plasma-impurity transport codes. The oscillations are characterized by significant variations of the impurity-radiated power and of the peak heat load on the divertor targets. Qualitative analysis of the divertor plasma oscillations reveals different mechanisms driving the oscillations in the cases of high- and low-Z impurity seeding. The oscillations caused by the high-Z impurities are excited near the X-point by an impurity-related instability of the radiation-condensation type, accompanied by parallel impurity ionmore » transport affected by the thermal and plasma friction forces. The driving mechanism of the oscillations induced by the low-Z impurities is related to the cross-field transport of the impurity atoms, causing alteration between the high and low plasma temperature regimes in the plasma recycling region near the divertor targets. As a result, the implications of the impurity-induced plasma oscillations for divertor operation in the next generation tokamaks are also discussed.« less

  7. Impurity-induced divertor plasma oscillations

    NASA Astrophysics Data System (ADS)

    Smirnov, R. D.; Kukushkin, A. S.; Krasheninnikov, S. I.; Pigarov, A. Yu.; Rognlien, T. D.

    2016-01-01

    Two different oscillatory plasma regimes induced by seeding the plasma with high- and low-Z impurities are found for ITER-like divertor plasmas, using computer modeling with the DUSTT/UEDGE and SOLPS4.3 plasma-impurity transport codes. The oscillations are characterized by significant variations of the impurity-radiated power and of the peak heat load on the divertor targets. Qualitative analysis of the divertor plasma oscillations reveals different mechanisms driving the oscillations in the cases of high- and low-Z impurity seeding. The oscillations caused by the high-Z impurities are excited near the X-point by an impurity-related instability of the radiation-condensation type, accompanied by parallel impurity ion transport affected by the thermal and plasma friction forces. The driving mechanism of the oscillations induced by the low-Z impurities is related to the cross-field transport of the impurity atoms, causing alteration between the high and low plasma temperature regimes in the plasma recycling region near the divertor targets. The implications of the impurity-induced plasma oscillations for divertor operation in the next generation tokamaks are also discussed.

  8. False Results Caused by Solvent Impurity in Tetrahydrofuran for MALDI TOF MS Analysis of Amines

    NASA Astrophysics Data System (ADS)

    Lou, Xianwen; Leenders, Christianus M. A.; van Onzen, Arthur H. A. M.; Bovee, Ralf A. A.; van Dongen, Joost L. J.; Vekemans, Jef A. J. M.; Meijer, E. W.

    2013-11-01

    Tetrahydrofuran (THF) is one of the most frequently used solvents in the MALDI TOF MS analysis of synthetic compounds. However, it should be used with caution because a trace amount of 4-hydroxybutanal (HBA) might be generated and accumulated in THF during storage. Since only a tiny amount of analytes is required in MALDI MS measurements, a trace amount of HBA might have a significant effect on the MS results. It was found that HBA will quickly react with primary and secondary amino compounds, leading to false results about the sample composition with an extra series of ions with additional mass of 70 Da in between. The formation of HBA can be inhibited by butylated hydroxytoluene (BHT) antioxidant. Therefore, when THF is required as the solvent for sample preparation, it is strongly recommended to use a BHT-stabilized one, at least for the analysis of compounds with amino groups.

  9. Research for fluid impurity detection based on ANN and infrared spectrum analysis technology

    NASA Astrophysics Data System (ADS)

    Ma, Huiping; Yuan, Feng

    2011-08-01

    A series of economic losses is caused by the biofilm of water pipe in industrial real water systems. Combined optical fiber self-relative technology with infrared spectrum analysis technology, real time detection technique for forming thickness and ingredient is put forward in the paper, which provides technical support and reliable data for analyzing biofouling influencing factors, contaminant separation and warning. Schematic diagram of biofouling detection is presented. Compensation technology based on radial basis function (RBF) neural network and learning algorithm are studied in order to solve the problem of measurement precision and range. Biofouling forming and optical characteristics in industrial real water systems are researched and standard specimen collection is set up. Correcting model explaining quantitatively relation between substance ingredient content and infrared spectrum based on partial least squares (PLS) method. A new method is provided for the research on biofouling in real water system, which can be used in other fields such as mining, environment protection, medical treatment and transportation of oil, gas and water.

  10. Impurity Crystal in a Bose-Einstein Condensate

    SciTech Connect

    Roberts, David C.; Rica, Sergio

    2009-01-16

    We investigate the behavior of impurity fields immersed in a larger condensate field in various dimensions. We discuss the localization of a single impurity field within a condensate and note the effects of surface energy. We derive the functional form of the attractive condensate-mediated interaction between two impurities. Generalizing the analysis to N impurity fields, we show that within various parameter regimes a crystal of impurity fields can form spontaneously in the condensate. Finally, the system of condensate and crystallized impurity structure is shown to have nonclassical rotational inertia, which is characteristic of superfluidity; i.e., the system can be seen to exhibit supersolid behavior.

  11. Analytical and mineralogical studies of ore and impurities from a chromite mineral using X-ray analysis, electrochemical and microscopy techniques.

    PubMed

    Sánchez-Ramos, S; Doménech-Carbó, A; Gimeno-Adelantado, J V; Peris-Vicente, J

    2008-02-15

    A wide analytical study of South African chromite ore, material with high interest in ceramic industry, has been carried out. With this purpose, an accurate chemical identification and mineralogical characterization of the mineral and the gangue have been performed using X-ray fluorescence (XRF), voltammetry, X-ray diffraction (XRD), light microscopy (LM), and scanning electron microscopy (SEM/EDX). The elemental composition of the sample (ore and gangue) has been obtained by XRF. The voltammetric analysis has allowed to demonstrate that iron in the sample was as Fe(II). The main compound of the chromite ore was a spinel (magnesiochromite ferroan), identified by XRD from the sample, which constitutes the chromite ore. This technique has also been useful to characterize some silicates as impurities in the chromite ore sample. Light microscopy has allowed the detection of the spinel and the identification of a silicate impurity (chrome chlorite), by means of their colouration. On the other hand, the other silicate impurity was identified as labradorite by means of X-ray microscopy by SEM/EDX. Finally, a strategy was developed to calculate the composition of each mineral in the unknown sample. The obtained results were: chromite spinel 82.89%, chlorite 12.79% and labradorite 4.32%. PMID:18371822

  12. Silicon materials task of the low cost solar array project (Phase III). Effects of impurities and processing on silicon solar cells. Phase III summary and seventeenth quarterly report, Volume 2: analysis of impurity behavior

    SciTech Connect

    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.

    1980-01-23

    The object of this phase of the program has been to investigate the effects of various processes, metal contaminants and contaminant-process interactions on the properties of silicon and on the performance of terrestrial silicon solar cells. The study encompassed topics including thermochemical (gettering) treatments, base doping concentration, base doping type (n vs. p), grain boundary-impurity interaction, non-uniformity of impurity distribution, long term effects of impurities, as well as synergic and complexing phenomena. The program approach consists in: (1) the growth of doubly and multiply-doped silicon single crystals containing a baseline boron or phosphorus dopant and specific impurities which produce deep levels in the forbidden band gap; (2) assessment of these crystals by chemical, microstructural, electrical and solar cell tests; (3) correlation of the impurity type and concentration with crystal quality and device performance; and (4) delineation of the role of impurities and processing on subsequent silicon solar cell performance. The overall results reported are based on the assessment of nearly 200 silicon ingots. (WHK)

  13. Third-order Scaling Analysis of various exchange interactions for a model Cerium impurity in normal Metals^*

    NASA Astrophysics Data System (ADS)

    Kim, T. S.; Cox, D. L.

    1996-03-01

    We introduce various exchange interactions for a model Ce^3+ impurity in cubic symmetry and analyze them using the perturbative renormalization group. In addition to the well-known one- and two-channel S_c=S_I=1/2 exchange interactions (Sc and SI are the conduction electron and the impurity pseudo spins, respectively), a new one-channel S_c=3/2, S_I=1/2 exchange interaction is found. This new exchange interaction competes with the two-channel exchange interaction. Using the perturbative renormalization group approach, we present all possible stable fixed points (one-, two-, and three-channel S_c=S_I=1/2 Kondo effect) and a ``zoo" of unstable fixed points some of which have non-Fermi liquid excitation spectra. ^* This work was supported by US DOE, BES, Materials Research.

  14. A Validated RP-HPLC Method for the Analysis of 1-Fluoronaphthalene and Its Process-Related Impurities.

    PubMed

    Karagiannidou, Evrykleia G; Bekiari, Eleni T; Vastardi, Elli I

    2015-09-01

    A simple and precise reversed-phase high-performance liquid chromatography method was developed and validated for the determination of 1-fluoronaphthalene and its process-related impurities, 1-aminonaphthalene, 1-nitronaphthalene, naphthalene and 2-fluoronaphthalene. 1-Fluoronaphthalene is the key starting material for the synthesis of duloxetine hydrochloride active pharmaceutical ingredient and is therefore a potential impurity of the API. The determination of the impurity profile is critical for the safety assessment of a substance and manufacturing process thereof. In duloxetine hydrochloride active pharmaceutical ingredient, only 1-fluoronaphthalene is detected and neither of its related impurities of 1-aminonaphthalene, 1-nitronaphthalene, naphthalene and 2-fluoronaphthalene. Chromatography was carried out on a Symmetry C18 (250 × 4.6 mm, 5 μm) column, using mobile phase A-a mixture of 0.01 Μ KH2PO4 buffer (pH 2.5 ± 0.1):methanol:acetonitrile in the ratio of 35:52:13 v/v/v and mobile phase B-a mixture of methanol:acetonitrile in the ratio of 80:20 v/v at a flow rate of 1.0 mL/min. The analytes were monitored using photo diode array detector at 230 nm. The proposed method is found to be having linearity in the concentration of 0.075-5.000 μg/mL, 0.150-5.000 μg/mL, 0.3125-5.000 μg/mL and 0.3125-5.000 μg/mL for 1-aminonaphthalene, 1-nitronaphthalene, naphthalene and 2-fluoronaphthalene, respectively, with correlation coefficients of 0.9998, 0.9998, 0.9997 and 0.9997, respectively. The proposed method was validated as per the International Conference on Harmonization guidelines. The mean recoveries for all the studied impurities are in the range of 90-110%. Due to its specificity, high precision and accuracy, the developed method can be used for the determination of 1-fluoronaphthalene, key starting material for the synthesis of duloxetine hydrochloride API. PMID:25713107

  15. Triaxially deformed relativistic point-coupling model for Λ hypernuclei: A quantitative analysis of the hyperon impurity effect on nuclear collective properties

    NASA Astrophysics Data System (ADS)

    Xue, W. X.; Yao, J. M.; Hagino, K.; Li, Z. P.; Mei, H.; Tanimura, Y.

    2015-02-01

    Background: The impurity effect of hyperons on atomic nuclei has received a renewed interest in nuclear physics since the first experimental observation of appreciable reduction of E 2 transition strength in low-lying states of the hypernucleus Λ7Li . Many more data on low-lying states of Λ hypernuclei will be measured soon for s d -shell nuclei, providing good opportunities to study the Λ impurity effect on nuclear low-energy excitations. Purpose: We carry out a quantitative analysis of the Λ hyperon impurity effect on the low-lying states of s d -shell nuclei at the beyond-mean-field level based on a relativistic point-coupling energy density functional (EDF), considering that the Λ hyperon is injected into the lowest positive-parity (Λs) and negative-parity (Λp) states. Method: We adopt a triaxially deformed relativistic mean-field (RMF) approach for hypernuclei and calculate the Λ binding energies of hypernuclei as well as the potential-energy surfaces (PESs) in the (β ,γ ) deformation plane. We also calculate the PESs for the Λ hypernuclei with good quantum numbers by using a microscopic particle rotor model (PRM) with the same relativistic EDF. The triaxially deformed RMF approach is further applied in order to determine the parameters of a five-dimensional collective Hamiltonian (5DCH) for the collective excitations of triaxially deformed core nuclei. Taking 25,27Mg Λ and Si31Λ as examples, we analyze the impurity effects of Λs and Λp on the low-lying states of the core nuclei. Results: We show that Λs increases the excitation energy of the 21+ state and decreases the E 2 transition strength from this state to the ground state by 12 %to17 % . On the other hand, Λp tends to develop pronounced energy minima with larger deformation, although it modifies the collective parameters in such a way that the collectivity of the core nucleus can be either increased or decreased. Conclusions: The quadrupole deformation significantly affects the

  16. A differential thermal analysis study of the effect of tramp impurities on the exothermic U sub 3 O sub 8 -Al reactions

    SciTech Connect

    Gray, L.W. ); Peacock, H.B. )

    1989-12-01

    Differential thermal analysis (DTA) has been used to study the effect of impurities on aluminothermic reactions between commercial type 101 aluminum powder and U{sub 3}O{sub 8} powder. No measurable effect (solid state reactions) was found below 660{degrees}C during differential thermal analysis studies of (1) loose blended powders, (2) blended and compressed powders, (3) blended, heated, and compressed powders, or (4) blended, compressed, and heated compacts containing less than 50,000 ppM impurities from group IA halide salts and group IIA oxides. It was determined that impurities (>5 wt %) of alkali metal chlorides, and alkaline earth oxides, cause minor modifications of the reaction thermograms above 800{degrees}C for molten aluminum metal with U{sub 3}O{sub 8}. It was also determined that attempts to prepare alkali, alkaline earth, and transition metal uranates under conditions via reaction below 660{degrees}C. In similar experiments where Fe{sub 2}O{sub 3} and NiO were substituted for U{sub 3}O{sub 8}, it was determined that NaCl does modify the reactions between aluminum metal and Fe{sub 2}O{sub 3} and between aluminum metal and NiO. With increasing NaCl concentrations, the temperature for initiation of the reaction moves to lower temperatures. At 10 wt % NaCl, the exothermic thermite'' reactions between aluminum and Fe{sub 2}O{sub 3} or NiO begin at approximately 640{degrees}C. 30 refs., 17 figs., 7 tabs.

  17. Chemical analysis of metal impurity distribution of zone-refined mercuric iodide by ICP-AES and DSC

    NASA Astrophysics Data System (ADS)

    Chen, K.-T.; Salary, L.; Burger, A.; Soria, E.; Antolak, A.; James, R. B.

    A mercuric iodide single crystal is being developed for X-ray and gamma-ray detector applications where high-purity starting material is required. Zone-refining processing has been proven to be an effective step in the purification of large amounts of mercuric iodide for crystal growth. In this study we used the Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) to identify and determine the distribution of impurity concentrations along the ampoule after zone-refining mercuric iodide. The results show that for Ag, Cu, Fe, Mg, Ca, Zn, Cr and Al, the zone-refining process does sweep the impurities to the last-to-freeze zone, due to an effective distribution coefficient, keff < 1. For Na, Ni, Cd, Mn and Pb the concentration gradient seems to be fairly independent of the position along the ingot. Differential Scanning Calorimetry was also employed to investigate the deviation from stoichiometry caused by the zone-refining process, and the results indicated that the first-to-freeze section is Hg-rich, and the middle section tends to become slightly Hg-rich, while the last-to-freeze section becomes I-rich.

  18. Impurities in snowpacks.

    PubMed

    Sommerfeld, R A

    1989-04-01

    Snow can be involved in the acquisition, transport, storage and release of atmospheric impurities. Because it can store impurities for periods of time ranging from hours to millenia, it provides a medium for monitoring atmospheric impurities for a wide range of time scales.In most climates, snow is involved in the precipitation process. It can acquire atmospheric impurities either as aerosols or as gases. The aereosols can be included in the body of the snow crystals or adhered to their surfaces. Gases may be included in bubbles, particularly in the case of rime, or adsorbed on the ice surfaces. The amount of ice surface in a small storm is about 10(10) m(2).Snow on the ground can store the impurities acquired in the precipitation process and can acquire additional impurities as dry deposition. The low temperatures and the fact that ice is a solid reduces biological activity and rates of inorganic reactions. However, the assumption that there is no activity in the winter is not well found. Exchange is possible between different layers of the snow and between the snow and the atmosphere, resulting in relocation of gases and aerosols. These processes also insure that the impurities reside on the exterior surfaces of the ice particles that form the snowpack. Biological activity is possible near the ground-snow interface in most climates.The seasonal snowpack releases its impurities when it melts. Because below freezing processes relocate any internal impurities to the ice surfaces within the snowpack, the impurities are available to the first melt water. Pulses of both acidic and alkalinic impurities have been observed with the initial snow melt water. However, the monitoring of such pulses is difficult and the measurements are inconsistent.Impurities are incorporated for longer periods of time in perennial snowpacks and finally in ice fields. These can be glaciers, or, at the largest scale, continental ice sheets. Coring such ice is expensive but provides data on

  19. Characterization of the isomeric configuration and impurities of (Z)-endoxifen by 2D NMR, high resolution LC⬜MS, and quantitative HPLC analysis.

    PubMed

    Elkins, Phyllis; Coleman, Donna; Burgess, Jason; Gardner, Michael; Hines, John; Scott, Brendan; Kroenke, Michelle; Larson, Jami; Lightner, Melissa; Turner, Gregory; White, Jonathan; Liu, Paul

    2014-01-01

    (Z)-Endoxifen (4-hydroxy-N-desmethyltamoxifen), an active metabolite generated via actions of CYP3A4/5 and CYP2D6, is a more potent selective estrogen receptor modulator (SERM) than tamoxifen. In the MCF-7 human mammary tumor xenograft model with female athymic mice, (Z)-endoxifen, at an oral dose of 4⬜8 mg/kg, significantly inhibits tumor growth. (Z)-Endoxifen's potential as an alternative therapeutic agent independent of CYP2D6 activities, which can vary widely in ER+ breast cancer patients, is being actively evaluated. This paper describes confirmation of the configuration of the active (Z)-isomer through 2D NMR experiments, including NOE (ROESY) to establish spatial proton⬜proton correlations, and identification of the major impurity as the (E)-isomer in endoxifen drug substance by HPLC/HRMS (HPLC/MS-TOF). Stability of NMR solutions was confirmed by HPLC/UV analysis. For pre-clinical studies, a reverse-phase HPLC⬜UV method, with methanol/water mobile phases containing 10 mM ammonium formate at pH 4.3, was developed and validated for the accurate quantitation and impurity profiling of drug substance and drug product. Validation included demonstration of linearity, method precision, accuracy, and specificity in the presence of impurities, excipients (for the drug product), and degradation products. Ruggedness and reproducibility of the method were confirmed by collaborative studies between two independent laboratories. The method is being applied for quality control of the API and oral drug product. Kinetic parameters of Z- to E-isomerization were also delineated in drug substance and in aqueous formulation, showing conversion at temperatures above 25 °C. PMID:24055701

  20. Flow injection combined with ICP-MS for accurate high throughput analysis of elemental impurities in pharmaceutical products according to USP <232>/<233>.

    PubMed

    Fischer, Lisa; Zipfel, Barbara; Koellensperger, Gunda; Kovac, Jessica; Bilz, Susanne; Kunkel, Andrea; Venzago, Cornel; Hann, Stephan

    2014-07-01

    New guidelines of the United States Pharmacopeia (USP), European Pharmacopeia (EP) and international organization (ICH, International Conference on Harmonization) regulating elemental impurity limits in pharmaceuticals seal the end of unspecific analysis of metal(oid)s as outlined in USP <231> and EP 2.4.8. Chapter USP <232> and EP 5.20 as well as drafts from ICH Q3D specify both daily doses and concentration limits of metallic impurities in pharmaceutical final products and in active pharmaceutical ingredients (API) and excipients. In chapters USP <233> and EP 2.4.20 method implementation, validation and quality control during the analytical process are described. By contrast with the--by now--applied methods, substance specific quantitative analysis features new basic requirements, further, significantly lower detection limits ask for the necessity of a general changeover of the methodology toward sensitive multi element analysis by ICP-AES and ICP-MS, respectively. A novel methodological approach based on flow injection analysis and ICP-SFMS/ICP-QMS for the quick and accurate analysis of Cd, Pb, As, Hg, Ir, Os, Pd, Pt, Rh, Ru, Cr, Mo, Ni, V, Cu, Mn, Fe and Zn in drug products by prior dilution, dissolution or microwave assisted closed vessel digestion according to the regulations is presented. In comparison to the acquisition of continuous signals, this method is advantageous with respect to the unprecedented high sample throughput due to a total analysis time of approximately 30s and the low sample consumption of below 50 μL, while meeting the strict USP demands on detection/quantification limits, precision and accuracy. PMID:24667566

  1. Impurity gettering in semiconductors

    DOEpatents

    Sopori, B.L.

    1995-06-20

    A process for impurity gettering in a semiconductor substrate or device such as a silicon substrate or device is disclosed. 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 C to about 700 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. 1 fig.

  2. Impurity gettering in semiconductors

    DOEpatents

    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.

  3. Quantitative high-performance liquid chromatography-tandem mass spectrometry impurity profiling methods for the analysis of parenteral infusion solutions for amino acid supplementation containing L-alanyl-L-glutamine.

    PubMed

    Schiesel, Simone; Lämmerhofer, Michael; Leitner, Alexander; Lindner, Wolfgang

    2012-10-12

    Potential impurities in a parenteral infusion solution for amino acid supplementation containing alanylglutamine (AlaGln) and glycyltyrosine (GlyTyr) as peptide constituents have been determined. Such complex multicomponent pharmaceutical formulations with reactive ingredients may yield a multitude of impurities in stress testing samples. Thus, three stability indicating LC-ESI-MS/MS methods were developed for the establishment of quantitative impurity profiles employing a Chiralpak QN-AX and a Polysulfoethyl A stationary phase in HILIC mode as well as a Gemini C18 stationary phase in gradient RPLC mode. The primary goal was to separate isobaric compounds (stereoisomers, constitutional isomers, retro-peptides) and to provide quantitative data of impurities identified in stressed nutritional infusion solutions. The optimized methods were calibrated by standard addition in the samples and validated according to ICH guidelines. The methods were then applied for the analysis of stressed sample solutions stored under different conditions. Major peptide impurities found in concentrations above the qualification threshold in stressed solutions stored at 40 °C for 6 months comprised cyclo(AlaGln) 808 μg/mL, pyroGluAla 122 μg/mL, AlaGlu 117 μg/mL, cycloGlyTyr 60 μg/mL, AlaGln epimers (DL+LD) 38 μg/mL, and TyrGly 27 μg/mL. A number of impurities above the reporting threshold were also detected including AlaAlaGln 18 μg/mL, cyclo(AlaGlu) 16 μg/mL, AlaGlu(AlaGln) 17 μg/mL, and AlaGlu(His) 12 μg/mL. The study showed that bioactive peptides may be formed in amino acid infusion solutions by condensation of amino acids and a careful control of these impurities is mandatory. PMID:22305362

  4. A Calibration to Predict the Concentrations of Impurities in Plutonium Oxide by Prompt Gamma Analysis Revision 2

    SciTech Connect

    Narlesky, Joshua Edward; Kelly, Elizabeth J.

    2015-09-10

    This report documents the new PG calibration regression equation. These calibration equations incorporate new data that have become available since revision 1 of “A Calibration to Predict the Concentrations of Impurities in Plutonium Oxide by Prompt Gamma Analysis” was issued [3] The calibration equations are based on a weighted least squares (WLS) approach for the regression. The WLS method gives each data point its proper amount of influence over the parameter estimates. This gives two big advantages, more precise parameter estimates and better and more defensible estimates of uncertainties. The WLS approach makes sense both statistically and experimentally because the variances increase with concentration, and there are physical reasons that the higher measurements are less reliable and should be less influential. The new magnesium calibration includes a correction for sodium and separate calibration equation for items with and without chlorine. These additional calibration equations allow for better predictions and smaller uncertainties for sodium in materials with and without chlorine. Chlorine and sodium have separate equations for RICH materials. Again, these equations give better predictions and smaller uncertainties chlorine and sodium for RICH materials.

  5. Preparation of phosphorylcholine-based hydrophilic monolithic column and application for analysis of drug-related impurities with capillary electrochromatography.

    PubMed

    Qiu, Danye; Li, Feng; Zhang, Mingyu; Kang, Jingwu

    2016-07-01

    A hydrophilic monolithic CEC column was prepared by thermal copolymerization of zwitterionic monomer 2-methacryloyloxyethyl phosphorylcholine (MPC), pentaerythritol triacrylate (PETA), either methacrylatoethyl trimethyl ammonium chloride (META) or sodium 2-methylpropene-1-sulfonate (MPS) in a polar binary porogen consisting of methanol and THF. A typical hydrophilic interaction LC retention mechanism was observed for low-molecular weight polar compounds including amides, nucleotides, and nucleosides in the separation mode of hydrophilic interaction CEC, when high content of ACN (>60%) was used as the mobile phase. The effect of the electrostatic interaction between the analytes and the stationary phase was found to be negligible. The poly(MPC-co-PETA-co-META or MPS) monolithic columns have an average column efficiency of 40 000 plates/m and displayed with a satisfactory repeatability in terms of migration time and peak areas. Finally, the column was successfully applied to determine the impurities of a positively charged drug pramipexole which are often separated by ion pair RP chromatography due to their high hydrophilicity. All four components can be baseline separated within 5 min with BGE consisting of ACN/20 mM ammonium formate buffer (pH 3.0; 80/20). PMID:27062582

  6. Determination of the impurities in drug products containing montelukast and in silico/in vitro genotoxicological assessments of sulfoxide impurity.

    PubMed

    Emerce, Esra; Cok, Ismet; Degim, I Tuncer

    2015-10-14

    Impurities affecting safety, efficacy, and quality of pharmaceuticals are of increasing concern for regulatory agencies and pharmaceutical industries, since genotoxic impurities are understood to play important role in carcinogenesis. The study aimed to analyse impurities of montelukast chronically used in asthma theraphy and perform genotoxicological assessment considering regulatory approaches. Impurities (sulfoxide, cis-isomer, Michael adducts-I&II, methylketone, methylstyrene) were quantified using RP-HPLC analysis on commercial products available in Turkish market. For sulfoxide impurity, having no toxicity data and found to be above the qualification limit, in silico mutagenicity prediction analysis, miniaturized bacterial gene mutation test, mitotic index determination and in vitro chromosomal aberration test w/wo metabolic activation system were conducted. In the analysis of different batches of 20 commercial drug products from 11 companies, only sulfoxide impurity exceeded qualification limit in pediatric tablets from 2 companies and in adult tablets from 7 companies. Leadscope and ToxTree programs predicted sulfoxide impurity as nonmutagenic. It was also found to be nonmutagenic in Ames MPF Penta I assay. Sulfoxide impurity was dose-dependent cytotoxic in human peripheral lymphocytes, however, it was found to be nongenotoxic. It was concluded that sulfoxide impurity should be considered as nonmutagenic and can be classified as ordinary impurity according to guidelines. PMID:26205398

  7. Impurity control in TFTR

    SciTech Connect

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  9. Proof-of-concept experiment for on-line laser induced breakdown spectroscopy analysis of impurity layer deposited on optical window and other plasma facing components of Aditya tokamak

    NASA Astrophysics Data System (ADS)

    Maurya, Gulab Singh; Kumar, Rohit; Kumar, Ajai; Rai, Awadhesh Kumar

    2015-12-01

    In the present manuscript, we demonstrate the design of an experimental setup for on-line laser induced breakdown spectroscopy (LIBS) analysis of impurity layers deposited on specimens of interest for fusion technology, namely, plasma-facing components (PFCs) of a tokamak. For investigation of impurities deposited on PFCs, LIBS spectra of a tokamak wall material like a stainless steel sample (SS304) have been recorded through contaminated and cleaned optical windows. To address the problem of identification of dust and gases present inside the tokamak, we have shown the capability of the apparatus to record LIBS spectra of gases. A new approach known as "back collection method" to record LIBS spectra of impurities deposited on the inner surface of optical window is presented.

  10. Proof-of-concept experiment for on-line laser induced breakdown spectroscopy analysis of impurity layer deposited on optical window and other plasma facing components of Aditya tokamak.

    PubMed

    Maurya, Gulab Singh; Kumar, Rohit; Kumar, Ajai; Rai, Awadhesh Kumar

    2015-12-01

    In the present manuscript, we demonstrate the design of an experimental setup for on-line laser induced breakdown spectroscopy (LIBS) analysis of impurity layers deposited on specimens of interest for fusion technology, namely, plasma-facing components (PFCs) of a tokamak. For investigation of impurities deposited on PFCs, LIBS spectra of a tokamak wall material like a stainless steel sample (SS304) have been recorded through contaminated and cleaned optical windows. To address the problem of identification of dust and gases present inside the tokamak, we have shown the capability of the apparatus to record LIBS spectra of gases. A new approach known as "back collection method" to record LIBS spectra of impurities deposited on the inner surface of optical window is presented. PMID:26724011

  11. Proof-of-concept experiment for on-line laser induced breakdown spectroscopy analysis of impurity layer deposited on optical window and other plasma facing components of Aditya tokamak

    SciTech Connect

    Maurya, Gulab Singh; Kumar, Rohit; Rai, Awadhesh Kumar; Kumar, Ajai

    2015-12-15

    In the present manuscript, we demonstrate the design of an experimental setup for on-line laser induced breakdown spectroscopy (LIBS) analysis of impurity layers deposited on specimens of interest for fusion technology, namely, plasma-facing components (PFCs) of a tokamak. For investigation of impurities deposited on PFCs, LIBS spectra of a tokamak wall material like a stainless steel sample (SS304) have been recorded through contaminated and cleaned optical windows. To address the problem of identification of dust and gases present inside the tokamak, we have shown the capability of the apparatus to record LIBS spectra of gases. A new approach known as “back collection method” to record LIBS spectra of impurities deposited on the inner surface of optical window is presented.

  12. Dynamical impurity problems

    SciTech Connect

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

    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.

  13. Macromolecule Crystal Quality Improvement in Microgravity: The Role of Impurities

    NASA Technical Reports Server (NTRS)

    Judge, Russell A.; Snell, Edward H.; Pusey, Marc L.; Sportiello, Michael G.; Todd, Paul; Bellamy, Henry; Borgstahl, Gloria E.; Pokros, Matt; Cassanto, John M.

    2000-01-01

    While macromolecule impurities may affect crystal size and morphology the over-riding question is; "How do macromolecule impurities effect crystal X-ray quality and diffraction resolution?" In the case of chicken egg white lysozyme, crystals can be grown in the presence of a number of impurities without affecting diffraction resolution. One impurity however, the lysozyme dimer, does negatively impact the X-ray crystal properties. Crystal quality improvement as a result of better partitioning of this impurity during crystallization in microgravity has been reported'. In our recent experimental work dimer partitioning was found to be not significantly different between the two environments. Mosaicity analysis of pure crystals showed a reduced mosaicity and increased signal to noise for the microgravity grown crystals. Dimer incorporation however, did greatly reduce the resolution limit in both ground and microgravity grown crystals. These results indicate that impurity effects in microgravity are complex and may rely on the conditions or techniques employed.

  14. Particle in cell/Monte Carlo collision analysis of the problem of identification of impurities in the gas by the plasma electron spectroscopy method

    NASA Astrophysics Data System (ADS)

    Kusoglu Sarikaya, C.; Rafatov, I.; Kudryavtsev, A. A.

    2016-06-01

    The work deals with the Particle in Cell/Monte Carlo Collision (PIC/MCC) analysis of the problem of detection and identification of impurities in the nonlocal plasma of gas discharge using the Plasma Electron Spectroscopy (PLES) method. For this purpose, 1d3v PIC/MCC code for numerical simulation of glow discharge with nonlocal electron energy distribution function is developed. The elastic, excitation, and ionization collisions between electron-neutral pairs and isotropic scattering and charge exchange collisions between ion-neutral pairs and Penning ionizations are taken into account. Applicability of the numerical code is verified under the Radio-Frequency capacitively coupled discharge conditions. The efficiency of the code is increased by its parallelization using Open Message Passing Interface. As a demonstration of the PLES method, parallel PIC/MCC code is applied to the direct current glow discharge in helium doped with a small amount of argon. Numerical results are consistent with the theoretical analysis of formation of nonlocal EEDF and existing experimental data.

  15. Quality by Design approach in the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol and its impurities.

    PubMed

    Jovanović, Marko; Rakić, Tijana; Tumpa, Anja; Jančić Stojanović, Biljana

    2015-06-10

    This study presents the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol, its endo-isomer and three impurities following Quality by Design (QbD) approach. The main objective of the method was to identify the conditions where adequate separation quality in minimal analysis duration could be achieved within a robust region that guarantees the stability of method performance. The relationship between critical process parameters (acetonitrile content in the mobile phase, pH of the water phase and ammonium acetate concentration in the water phase) and critical quality attributes is created applying design of experiments methodology. The defined mathematical models and Monte Carlo simulation are used to evaluate the risk of uncertainty in models prediction and incertitude in adjusting the process parameters and to identify the design space. The borders of the design space are experimentally verified and confirmed that the quality of the method is preserved in this region. Moreover, Plackett-Burman design is applied for experimental robustness testing and method is fully validated to verify the adequacy of selected optimal conditions: the analytical column ZIC HILIC (100 mm × 4.6 mm, 5 μm particle size); mobile phase consisted of acetonitrile-water phase (72 mM ammonium acetate, pH adjusted to 6.5 with glacial acetic acid) (86.7:13.3) v/v; column temperature 25 °C, mobile phase flow rate 1 mL min(-1), wavelength of detection 254 nm. PMID:25796982

  16. Formation of copper(I) from trace levels of copper(II) as an artifactual impurity in the HPLC analysis of olanzapine.

    PubMed

    Baertschi, Steven W; Olsen, Bernard A; Wozniak, Timothy J; Toltl, Nick; O'Shea, Colette; Jansen, Patrick J

    2016-06-01

    An analytical artifact peak appearing to be an impurity was observed intermittently among several laboratories performing HPLC analyses of olanzapine drug substance and formulation samples. The artifact peak was identified as Cu(I) that was formed from the reaction of trace amounts of Cu(II) with olanzapine in the sample solution. Unlike Cu(II), Cu(I) was retained under the ion-pairing HPLC conditions used for analysis. A reaction mechanism was postulated whereby Cu(II) present in the sample solution oxidizes olanzapine to a radical-cation, resulting in formation of Cu(I) and three oxidation products of olanzapine including a previously unknown oxidation product that was identified as hydroxy-olanzapine. Acetonitrile in the sample solution was necessary for the reaction to occur. As little as 100 ppb Cu(II) in the sample solution produced a Cu(I) peak, that by peak area, corresponded to about 0.1% relative to the olanzapine peak. The hydroxy-olanzapine oxidation product was also detectable, but the relative peak area was much smaller. To prevent formation of the Cu(I) artifact peak, EDTA was added to the sample solvent to complex any trace Cu(II) that might be present. The addition of EDTA was shown to prevent Cu(I) formation when Cu(II) was present at levels of 4ppm in the sample solution. PMID:27023131

  17. Quasiparticle interference from magnetic impurities

    NASA Astrophysics Data System (ADS)

    Derry, Philip G.; Mitchell, Andrew K.; Logan, David E.

    2015-07-01

    Fourier transform scanning tunneling spectroscopy (FT-STS) measures the scattering of conduction electrons from impurities and defects, giving information about the electronic structure of both the host material and adsorbed impurities. We interpret such FT-STS measurements in terms of the quasiparticle interference (QPI), here investigating in detail the QPI due to single magnetic impurities adsorbed on a range of representative nonmagnetic host surfaces, and contrasting with the case of a simple scalar impurity or point defect. We demonstrate how the electronic correlations present for magnetic impurities markedly affect the QPI, showing, e.g., a large intensity enhancement due to the Kondo effect, and universality at low temperatures/scanning energies. The commonly used joint density of states interpretation of FT-STS measurements is also considered, and shown to be insufficient in many cases, including that of magnetic impurities.

  18. Impurity profile of rifaximin produced in China.

    PubMed

    Liuchao; Maixi; Wangchao; Wan, Chunpeng

    2012-04-01

    Impurity profiles of rifaximin produced in China were investigated systematically by LCMS methods. Eleven impurities from the raw materials of rifaximin produced in China were detected. We adopted the Diagnostic fragment-ion-based extension strategy (DFIBES) for deducing the structure of unknown impurities. Impurity 1 was the 30-hydroxylated product of rifaximin. Impurity 2 was the 25-deacetyled rifaximin. Impurity 6 was the isomeride of rifaximin. Impurity 9 was rifamycin-O. PMID:22570932

  19. An integrated quality by design and mixture-process variable approach in the development of a capillary electrophoresis method for the analysis of almotriptan and its impurities.

    PubMed

    Orlandini, S; Pasquini, B; Stocchero, M; Pinzauti, S; Furlanetto, S

    2014-04-25

    The development of a capillary electrophoresis (CE) method for the assay of almotriptan (ALM) and its main impurities using an integrated Quality by Design and mixture-process variable (MPV) approach is described. A scouting phase was initially carried out by evaluating different CE operative modes, including the addition of pseudostationary phases and additives to the background electrolyte, in order to approach the analytical target profile. This step made it possible to select normal polarity microemulsion electrokinetic chromatography (MEEKC) as operative mode, which allowed a good selectivity to be achieved in a low analysis time. On the basis of a general Ishikawa diagram for MEEKC methods, a screening asymmetric matrix was applied in order to screen the effects of the process variables (PVs) voltage, temperature, buffer concentration and buffer pH, on critical quality attributes (CQAs), represented by critical separation values and analysis time. A response surface study was then carried out considering all the critical process parameters, including both the PVs and the mixture components (MCs) of the microemulsion (borate buffer, n-heptane as oil, sodium dodecyl sulphate/n-butanol as surfactant/cosurfactant). The values of PVs and MCs were simultaneously changed in a MPV study, making it possible to find significant interaction effects. The design space (DS) was defined as the multidimensional combination of PVs and MCs where the probability for the different considered CQAs to be acceptable was higher than a quality level π=90%. DS was identified by risk of failure maps, which were drawn on the basis of Monte-Carlo simulations, and verification points spanning the design space were tested. Robustness testing of the method, performed by a D-optimal design, and system suitability criteria allowed a control strategy to be designed. The optimized method was validated following ICH Guideline Q2(R1) and was applied to a real sample of ALM coated tablets. PMID

  20. Principal component analysis to assess the composition and fate of impurities in a large river-embedded reservoir: Qingcaosha Reservoir.

    PubMed

    Ou, Hua-Se; Wei, Chao-Hai; Deng, Yang; Gao, Nai-Yun

    2013-08-01

    Qingcaosha Reservoir (QR) is the largest river-embedded reservoir in east China, which receives its source water from the Yangtze River (YR). The temporal and spatial variations in dissolved organic matter (DOM), chromophoric DOM (CDOM), nitrogen, phosphorus and phytoplankton biomass were investigated from June to September in 2012 and were integrated by principal component analysis (PCA). Three PCA factors were identified: (1) phytoplankton related factor 1, (2) total DOM related factor 2, and (3) eutrophication related factor 3. Factor 1 was a lake-type parameter which correlated with chlorophyll-a and protein-like CDOM (r = 0.793 and r = 0.831, respectively). Factor 2 was a river-type parameter which correlated with total DOC and humic-like CDOM (r = 0.668 and r = 0.726, respectively). Factor 3 correlated with total nitrogen and phosphorus (r = 0.864 and r = 0.621, respectively). The low flow speed, self-sedimentation and nutrient accumulation in QR resulted in increases in PCA factor 1 scores (phytoplankton biomass and derived CDOM) in the spatial scale, indicating a change of river-type water (YR) to lake-type water (QR). In summer, the water temperature variation induced a growth-bloom-decay process of phytoplankton combined with the increase of PCA factor 2 (humic-like CDOM) in the QR, which was absent in the YR. PMID:23824274

  1. A high pH based reversed-phase high performance liquid chromatographic method for the analysis of aminoglycoside plazomicin and its impurities.

    PubMed

    Tan, Li; Wlasichuk, Kenneth B; Schmidt, Donald E; Campbell, Robert L; Hirtzer, Pam; Cheng, Lisa; Karr, Dane E

    2012-07-01

    A reversed-phase high performance liquid chromatographic (RP-HPLC) method has been developed for the aminoglycoside (AG) plazomicin (ACHN-490). This method employed a high pH mobile phase (pH>11) with a gradient of 0.25 M ammonium hydroxide in water and acetonitrile, an XBridge C(18) column and UV detection at 210 nm. Although the molar UV absorption of plazomicin is weak, the high pH conditions of this method allow for higher loadings, which compensates for the inherent low UV sensitivity. Under these high pH conditions, impurities and degradants were base line separated from plazomicin. The mobile phases used for this method allowed for on-line mass detection for the impurities and degradants. The RP-HPLC method has been validated in terms of specificity, linearity and range, accuracy, and precision. The analytical method met specificity requirements of a homogenous peak with no interferences from the blank or from the known impurities in plazomicin. The linearity of the method for the plazomicin impurity determination was excellent, with a coefficient of determination (r(2)) of 0.9993, over the freebase (FB) concentration range of 0.0025-3.0 mg/mL. The method is capable of detecting impurities down to 0.1% of the peak area of plazomicin. A single point standard at a concentration of 1.0 mg/mL FB was validated over the range of 50-150% for quantitation of the freebase content (the assay) in bulk drug substance. The mean recoveries of FB are in the range 98.6-102.0% with a mean RSD (relative standard deviation) <1.0%. The study also examined the method precision for purity, impurities and the assay with two instruments on two different days. The method showed adequate accuracy and precision for the intended use. This high pH method was successfully used to determine the impurity and measure the drug content in the final plazomicin drug substance. In addition, the method with an on-line mass spectrometry detector has been used to characterize the structures of the

  2. The effect of secondary impurities on solar cell performance

    NASA Technical Reports Server (NTRS)

    Hill, D. E.; Gutsche, H. W.; Wang, M. S.; Gupta, K. P.; Tucker, W. F.; Dowdy, J. D.; Crepin, R. J.

    1976-01-01

    Czochralski and float zone sigle crystals of silicon were doped with the primary impurities B or P so that a resistivity of 0.5 ohm cm resulted, and in addition doped with certain secondary impurities including Al, C, Cr, Cu, Fe, Mg, Mn, Na, Ni, O, Ti, V, and Zr. The actual presence of these impurities was confirmed by analysis of the crystals. Solar cell performance was evaluated and found to be degraded most significantly by Ti, V, and Zr and to some extent by most of the secondary impurities considered. These results are of significance to the low cost silicon program, since any such process would have to yield at least tolerable levels of these impurities.

  3. Impurity Extraction by Droplets

    NASA Technical Reports Server (NTRS)

    Morrison, G.; Kincaid, J. M.

    1985-01-01

    The goals are to model and to measure the phase equilibrium properties of a finely divided fluid containing a large number of chemically similar species. The objective is to develop an accurate, usable model for such phenomena as pollutant extraction of rain clouds, industrial separation in spray towers, and separation in emulsions. The project was designed as a hierarchy of complementary theoretical and experimental steps. A theory was developed to describe the segregation of complex impurities at the interface of a solvent. This phenomenon is important in phase behavior when a large fraction of molecules in a material are near an interface, the situation in a finely divided material. The theory will be modified to account for the effect of surface curvature on the surface tension. The study of mixtures differs from pure fluids not only because of the surface effects but also because composition differences between the droplet and the surrounding vapor can stabilize a droplet with respect to a bulk phase.

  4. The impurity of radioiodinated triolein

    PubMed Central

    Kennedy, J. A.; Kinloch, J. D.

    1964-01-01

    Commercially supplied radioiodinated triolein has been shown by thin-layer chromatography and silicic acid column chromatography to contain impurities, consisting mainly of diglycerides and monoglycerides, but also a small amount of free fatty acid. The effect of these impurities on the radioiodinated triolein absorption test requires further investigation. Images PMID:14149942

  5. Impurities in silicon solar cells

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.

    1985-01-01

    Metallic impurities, both singly and in combinations, affect the performance of silicon solar cells. Czochralski silicon web crystals were grown with controlled additions of secondary impurities. The primary electrical dopants were boron and phosphorus. The silicon test ingots were grown under controlled and carefully monitored conditions from high-purity charge and dopant material to minimize unintentional contamination. Following growth, each crystal was characterized by chemical, microstructural, electrical, and solar cell tests to provide a detailed and internally consistent description of the relationships between silicon impurity concentration and solar cell performance. Deep-level spectroscopy measurements were used to measure impurity concentrations at levels below the detectability of other techniques and to study thermally-induced changes in impurity activity. For the majority of contaminants, impurity-induced performance loss is due to a reduction of the base diffusion length. From these observations, a semi-empirical model which predicts cell performance as a function of metal impurity concentration was formulated. The model was then used successfully to predict the behavior of solar cells bearing as many as 11 different impurities.

  6. Isolation and structural elucidation of two impurities from a diacerein bulk drug.

    PubMed

    Ashok, Chaudhari; Golak, Maikap; Adwait, Deo; Krishna, Vivek; Himani, Agrawal; Umesh, Peshawe; Amol, Gawande; Srinivas, Sompalli; Sharad, Mane; Deepali, Jadhav; Atul, Chaudhari

    2009-02-20

    Two impurities were found in the crude sample of diacerein. The level of these impurities 1.14% and 1.24% were detected by isocratic reverse-phase high performance liquid chromatography (HPLC). The molecular weights of the impurities were determined by liquid chromatography-mass spectroscopy (LC-MS) analysis. These impurities were isolated from crude sample of diacerein by reverse-phase preparative liquid chromatography. These impurities were characterized as 5-acetoxy-4-hydroxy-9,10-dioxo-9,10-dihydroanthracene-2-carboxylic acid (Impurity-1) and 4-acetoxy-5-hydroxy-9,10-dioxo-9,10-dihydroanthracene-2-carboxylic acid (Impurity-2) respectively. Structural elucidation of both the impurities were carried out by (1)H NMR, (13)C NMR, DEPT, 1D NOESY, MS and IR spectroscopy. PMID:19131202

  7. Trace analysis of impurities in bulk gases by gas chromatography-pulsed discharge helium ionization detection with "heart-cutting" technique.

    PubMed

    Weijun, Yao

    2007-10-12

    A method has been developed for the detection of low-nL/L-level impurities in bulk gases such as H(2), O(2), Ar, N(2), He, methane, ethylene and propylene, respectively. The solution presented here is based upon gas chromatography-pulsed discharge helium ionization detection (GC-PDHID) coupled with three two-position valves, one two-way solenoid valve and four packed columns. During the operation, the moisture and heavy compounds are first back-flushed via a pre-column. Then the trace impurities (except CO(2) which is diverted to a separate analytical column for separation and detection) together with the matrix enter onto a main column, followed by the heart-cut of the impurities onto a longer analytical column for complete separation. Finally the detection is performed by PDHID. This method has been applied to different bulk gases and the applicability of detecting impurities in H(2), Ar, and N(2) are herewith demonstrated. As an example, the resulting detection limit of 100 nL/L and a dynamic range of 100-1000 nL/L have been obtained using an Ar sample containing methane. PMID:17850804

  8. Forced degradation and impurity profiling: recent trends in analytical perspectives.

    PubMed

    Jain, Deepti; Basniwal, Pawan Kumar

    2013-12-01

    This review describes an epigrammatic impression of the recent trends in analytical perspectives of degradation and impurities profiling of pharmaceuticals including active pharmaceutical ingredient (API) as well as drug products during 2008-2012. These recent trends in forced degradation and impurity profiling were discussed on the head of year of publication; columns, matrix (API and dosage forms) and type of elution in chromatography (isocratic and gradient); therapeutic categories of the drug which were used for analysis. It focuses distinctly on comprehensive update of various analytical methods including hyphenated techniques for the identification and quantification of thresholds of impurities and degradants in different pharmaceutical matrices. PMID:23969330

  9. Mobile impurities in ferromagnetic liquids

    NASA Astrophysics Data System (ADS)

    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.

  10. Identification, isolation and characterization of potential process-related impurity and its degradation product in vildagliptin.

    PubMed

    Kumar, Neeraj; Devineni, Subba Rao; Singh, Gurmeet; Kadirappa, A; Dubey, Shailendra Kumar; Kumar, Pramod

    2016-02-01

    Vildagliptin is a member of a new class of oral anti-diabetic drug. One unknown impurity was identified in the range of 0.01-0.06% in different laboratory batches of vildagliptin along with known impurities by HPLC analysis. The structure of unknown impurity was proposed as (2S)-1-[2-[(3-hydroxyadamantan-1-yl)imino]acetyl]pyrrolidine-2-carbonitrile (Impurity-E) using LC/ESI-MS(n) study. The unknown impurity was found to be unstable in diluent (H2O:CH3CN) and degrading into another stable impurity. The degraded stable impurity was isolated from enriched reaction crude sample by semi preparative liquid chromatography. The structure of stable impurity was established using FT-IR, NMR ((1)H, (13)C and DEPT), 2D NMR (HSQC, HMBC and COSY) and mass spectral data as (8aS)-3-hydroxy-octahydropyrrolo[1,2-a]piperazine-1,4-dione (Impurity-F). Impurity identification, abnormal behaviour of impurity-E, isolation of impurity-F, fragmentation mechanism and structural elucidation were also discussed. PMID:26678178

  11. Theoretical analysis of structure and formation energy of impurity-doped Mg2Si: Comparison of first-principles codes for material properties

    NASA Astrophysics Data System (ADS)

    Hirayama, Naomi; Iida, Tsutomu; Funashima, Hiroki; Morioka, Shunsuke; Sakamoto, Mariko; Nishio, Keishi; Kogo, Yasuo; Takanashi, Yoshifumi; Hamada, Noriaki

    2015-07-01

    We theoretically investigate the impurity doping effects on the structural parameters such as lattice constant, atomic positions, and site preferences of impurity dopants for Al-doped magnesium silicide (Mg2Si) crystal using the first-principles calculation methods. We present comparison between several codes: ABCAP, Quantum Espresso, and Machikaneyama2002 (Akai KKR), which are based on the full-potential linearized augmented plane-wave method, the pseudopotential method, and KKR/GGA Green’s function method, respectively. As a result, any codes used in the present study exhibit qualitative consistency both in the dependence of the lattice constants on the doping concentration and the energetic preference of the Al atom for the following sites; substitutional Si and Mg sites, and interstitial 4b site; in particular, ABCAP, which is based on the all-electron full-potential method, and Quantum Espresso, which is a code of the pseudopotential method, produce closely-resemble calculation results. We also discuss the effects of local atomic displacement owing to the presence of impurities to the structural parameters of a bulk. Using the analytical method considering the local atomic displacement, moreover, we evaluate the formation energy of Na- and B-doped systems as examples of p-type doping in order to examine the possilbility of realizing p-type Mg2Si.

  12. Recent trends in the impurity profile of pharmaceuticals

    PubMed Central

    Pilaniya, Kavita; Chandrawanshi, Harish K.; Pilaniya, Urmila; Manchandani, Pooja; Jain, Pratishtha; Singh, Nitin

    2010-01-01

    Various regulatory authorities such as the International Conference on Harmonization (ICH), the United States Food and Drug administration (FDA), and the Canadian Drug and Health Agency (CDHA) are emphasizing on the purity requirements and the identification of impurities in Active Pharmaceutical Ingredients (APIs). The various sources of impurity in pharmaceutical products are — reagents, heavy metals, ligands, catalysts, other materials like filter aids, charcoal, and the like, degraded end products obtained during \\ after manufacturing of bulk drugs from hydrolysis, photolytic cleavage, oxidative degradation, decarboxylation, enantiomeric impurity, and so on. The different pharmacopoeias such as the British Pharmacopoeia, United State Pharmacopoeia, and Indian Pharmacopoeia are slowly incorporating limits to allowable levels of impurities present in APIs or formulations. Various methods are used to isolate and characterize impurities in pharmaceuticals, such as, capillary electrophoresis, electron paramagnetic resonance, gas–liquid chromatography, gravimetric analysis, high performance liquid chromatography, solid-phase extraction methods, liquid–liquid extraction method, Ultraviolet Spectrometry, infrared spectroscopy, supercritical fluid extraction column chromatography, mass spectrometry, Nuclear magnetic resonance (NMR) spectroscopy, and RAMAN spectroscopy. Among all hyphenated techniques, the most exploited techniques for impurity profiling of drugs are Liquid Chromatography (LC)-Mass Spectroscopy (MS), LC-NMR, LC-NMR-MS, GC-MS, and LC-MS. This reveals the need and scope of impurity profiling of drugs in pharmaceutical research. PMID:22247862

  13. Impurity profiling of methamphetamine hydrochloride drugs seized in the Philippines.

    PubMed

    Dayrit, Fabian M; Dumlao, Morphy C

    2004-08-11

    Methamphetamine hydrochloride is one of the most widely used illicit drugs in the Philippines. In this study, we describe the application of cluster analysis of trace impurities in the profiling of the seized methamphetamine drug samples. Thirty milligrams of a homogenized drug sample were dissolved in 1 mL of pH 10.5 buffer solution and extracted with ethyl acetate containing three internal standards. The trace impurities were identified using gas chromatography-mass spectrometry (GC-MS) and quantified by gas chromatography with a flame ionization detector (GC-FID). Following previously reported methodologies, 30 impurity peaks were selected from the GC-FID chromatograms. The peak areas and retention times were referenced to the internal standards. The peak areas of the selected peaks were then grouped for cluster analysis. In order to check for consistency of clustering, two further cluster analyses were performed using 40 and 50 impurity peaks. Changes in clustering were observed in going from 30 to 40 impurity peaks, while analyses using 40 and 50 impurity peaks gave similar results. Thus, for the seized drug samples used in this study, cluster analysis using at least 40 impurity peaks showed better consistency of clustering as compared to analysis using 30 peaks only. Ten of the impurity peaks were identified, of which four were identified for the first time in methamphetamine drug samples. These are p-bromotoluene, N-benzyl amphetamine, N-ethyl amphetamine, and N-ethyl methamphetamine. The presence of phenyl-2-propanone (P2P), N,N-dimethyl amphetamine, and N-formyl amphetamine is indicative that these casework samples were synthesized using the Leuckart method. PMID:15240018

  14. Combining impurity X-ray and impurity density measurements to determine Zeff

    NASA Astrophysics Data System (ADS)

    Nornberg, M. D.; Galante, M. E.; Reusch, L. M.; den Hartog, D. J.; Franz, P.; Stephens, H. D.

    2015-11-01

    Determining the resistive dissipation of hot plasmas requires knowledge of the effective charge Zeff. Typically Zeff is determined from visible bremsstrahlung emission. In limiter plasmas with relatively high core and edge neutral density, the neutrals likely contribute as much emission to the visible spectrum as do the impurities. By using sufficiently thick Be filters, detected soft x-ray emission can be limited to a region of the spectrum dominated by bremsstrahlung and impurity recombination. Modeling this emission requires good constraints on the impurity density profiles and charge state balance. This information can be supplied by charge exchange recombination measurements (CHERS). Combining these two different diagnostic measurements within a Bayesian framework enables the self-consistent determination of Zeff = 1 . 9 +/- 0 . 1 in the core of MST RFP plasmas with tearing mode suppression. This integrated data analysis (IDA) has the additional benefit of helping identify systematic uncertainties in the individual measurements and facilitates constraining the densities of other impurities for which there are no CHERS measurements. This work is supported by the US DOE.

  15. Impurity bubbles in a BEC

    NASA Astrophysics Data System (ADS)

    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.

  16. Studying the impurity charge and main ion mass dependence of impurity confinement in ECR-heated TJ-II stellarator

    NASA Astrophysics Data System (ADS)

    Zurro, B.; Hollmann, E. M.; Baciero, A.; Ochando, M. A.; McCarthy, K. J.; Medina, F.; Velasco, J. L.; Pastor, I.; Baião, D.; de la Cal, E.; Rapisarda, D.; the TJ-II Team

    2014-12-01

    The dependence of impurity confinement time on the charge and mass of the impurity ions injected from various samples (LiF, BN, W) by the laser blow-off method is reported for electron cyclotron heated discharges of the TJ-II heliac. Distinct impurity confinements are distinguished clearly for these injected ions in the plasma core as revealed by soft x-ray analysis and by tomographic reconstruction of bolometer array signals. A dependence of impurity confinement with charge seems to be the most probable explanation, as confirmed by the analysis of spectrally resolved data in the vacuum-ultraviolet range. This is discussed in terms of the dependence of impurity neoclassical transport on the background radial electric field. In addition, the impurity confinement of LiF is studied for a set of discharges in which the hydrogenic isotope mixture (H, D) is known (and evolves along the experiment), revealing a moderate isotope effect that is observed for the first time in particle confinement in a stellarator. This effect is consistent with a similar effect reported in global energy confinement time in the ATF stellarator.

  17. Ultra-sensitive detection of tumorigenic cellular impurities in human cell-processed therapeutic products by digital analysis of soft agar colony formation.

    PubMed

    Kusakawa, Shinji; Yasuda, Satoshi; Kuroda, Takuya; Kawamata, Shin; Sato, Yoji

    2015-01-01

    Contamination with tumorigenic cellular impurities is one of the most pressing concerns for human cell-processed therapeutic products (hCTPs). The soft agar colony formation (SACF) assay, which is a well-known in vitro assay for the detection of malignant transformed cells, is applicable for the quality assessment of hCTPs. Here we established an image-based screening system for the SACF assay using a high-content cell analyzer termed the digital SACF assay. Dual fluorescence staining of formed colonies and the dissolution of soft agar led to accurate detection of transformed cells with the imaging cytometer. Partitioning a cell sample into multiple wells of culture plates enabled digital readout of the presence of colonies and elevated the sensitivity for their detection. In practice, the digital SACF assay detected impurity levels as low as 0.00001% of the hCTPs, i.e. only one HeLa cell contained in 10,000,000 human mesenchymal stem cells, within 30 days. The digital SACF assay saves time, is more sensitive than in vivo tumorigenicity tests, and would be useful for the quality control of hCTPs in the manufacturing process. PMID:26644244

  18. Endohedral impurities in carbon nanotubes.

    PubMed

    Clougherty, Dennis P

    2003-01-24

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value. The effective potential is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale. PMID:12570507

  19. Endohedral Impurities in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis

    2003-03-01

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Treating the distortion within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value g_c. The effective potential in the symmetry-broken state is found to have O(2) symmetry, in agreement with numerical calculations. The consequences of such a distortion on electronic transport will be discussed.

  20. Endohedral Impurities in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis P.

    2003-01-01

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value. The effective potential is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale.

  1. ALUMINUM IMPURITY DIFFUSION IN MAGNESIUM

    SciTech Connect

    Brennan, Sarah; Warren, Andrew; Coffey, Kevin; Kulkarni, Nagraj S; Todd, Peter J; Sohn, Yong Ho; Klimov, Mikhail

    2012-01-01

    The Al impurity diffusion in polycrystalline Mg (99.9%) via depth profiling with secondary ion mass spectrometry was studied in the temperature range of 673-573K, utilizing the thin film method and thin film solution to the diffusion equation. Multiple samples were utilized and multiple profiles were obtained to determine statistically confident coefficient with maximum standard deviation of 16%. Activation energy and pre-exponential factor of Al impurity diffusion in Mg was determined as 155 kJ/mole and 3.9 x 10-3 m2/sec.

  2. Assessing the 210At impurity in the production of 211At for radiotherapy by 210Po analysis via isotope dilution alpha spectrometry.

    PubMed

    Schultz, Michael K; Hammond, Michelle; Cessna, Jeffrey T; Plascjak, Paul; Norman, Bruce; Szajek, Lawrence; Garmestani, Kayhan; Zimmerman, Brian E; Unterweger, Michael

    2006-01-01

    A method for assessing the impurity 210At in cyclotron-produced 211At via isotope dilution alpha spectrometry is presented. The activity of 210At is quantified by measuring the activity of daughter nuclide 210Po. Counting sources are prepared by spontaneous deposition of Po on a silver disc. Activity of 210At (at the time of 210Po maximum activity) is found to be 83.5+/-9.0 Bq, corresponding to an atom ratio (210At:211At at the time of distillation) of 0.010+/-0.007% (k=2). The method produces high-quality alpha spectra, with baseline alpha-peak resolution and chemical yields of greater than 85%. PMID:16563782

  3. Synthesis and Characterization of Organic Impurities in Bortezomib Anhydride Produced by a Convergent Technology

    PubMed Central

    Ivanov, Andrey S.; Shishkov, Sergey V.; Zhalnina, Anna A.

    2012-01-01

    A profile of impurities in bortezomib anhydride, produced by a recently developed convergent technology, has been characterized. HPLC-MS analysis of the drug essence revealed three impurities: an epimer of bortezomib, resulting from partial racemization of l-phenylalanine’s stereogenic center during the chemical synthesis, and two epimeric products of oxidative degradation of bortezomib, in which boron is replaced by the OH group. The impurities were obtained by chemical synthesis and characterized by physical methods. PMID:22396904

  4. Control of impurities in toroidal plasma devices

    DOEpatents

    Ohkawa, Tihiro

    1980-01-01

    A method and apparatus for plasma impurity control in closed flux plasma systems such as Tokamak reactors is disclosed. Local axisymmetrical injection of hydrogen gas is employed to reverse the normally inward flow of impurities into the plasma.

  5. Spectroscopic studies of impurity densities and impurity transport

    NASA Astrophysics Data System (ADS)

    Behringer, K.

    1992-06-01

    Spectrometers and spectra, mainly from JET, are discussed with respect to diagnostic potential and calibration problems. Spatial scan facilities or multichord diagnostics are essential for transport investigations, and several possibilities are shown. The interpretation of spectral line radiation usually requires the availability of impurity transport codes, which calculate the ionization balance in the presence of transport, the line emissivities and the total impurity radiation. Some atomic physics prerequisites of such codes are discussed. Theoretical and experimental approaches to the transport problem are investigated using ASDEX and JET results for anomalous transport. The occasional observation of neoclassical accumulation, for example after pellet injection, is presented and respective modeling is described. Some H mode transport phenomena are mentioned.

  6. Fundamental aspects of metallic impurities and impurity interactions in silicon during device processing

    SciTech Connect

    Graff, K.

    1995-08-01

    A review on the behavior of metallic impurities in silicon can be considerably simplified by a restriction on pure, dislocation-free, monocrystalline silicon. In this case interactions between different impurities and between impurities and grown-in lattice defects can be reduced. This restriction is observed in Chapter 1 for discussing the general behavior of metallic impurities in silicon.

  7. Observation of impurity accumulation and concurrent impurity influx in PBX

    SciTech Connect

    Sesnic, S.S.; Fonck, R.J.; Ida, K.; Bol, K.; Couture, P.; Gammel, G.; Kaita, R.; Kaye, S.; Kugel, H.; LeBlanc, B.

    1986-07-01

    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, Zeff peaks in the center to values of about 5. The central metallic densities can be high, n/sub met//n/sub e/ approx. = 0.01, resulting in central radiated power densities in excess of 1 W/cm/sup 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 6 x 10/sup 10/ and 10 x 10/sup 10/ particles/cm/sup 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 3 x 10/sup 12/ and 1 x 10/sup 12/ particles/cm/sup 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.

  8. Isolation, identification and characterization of novel process-related impurities in flupirtine maleate.

    PubMed

    Zhang, Dengfeng; Song, Xin; Su, Jiangtao

    2014-03-01

    Flupirtine maleate is a centrally acting, non-opioid, nonsteroidal antiinflammatory analgesic. During the manufacturing of flupirtine maleate, two unknown impurities present in the laboratory batches in the range of 0.05-1.0% along with the known impurities in HPLC analysis. These unknown impurities were obtained from the enriched mother liquor by column chromatography. Based on the complete spectral analysis (MS, (1)H, (13)C, 2D NMR and IR) and knowledge of the synthetic scheme of flupirtine maleate, these two new impurities were designated as diethyl 5-((4-fluorobenzyl)amino)-2-oxo-1H-imidazo[4,5-b]pyridine-1,3(2H)-dicarboxylate (impurity-I) and diethyl(6-((4-fluorobenzyl)amino)pyridine-2,3-diyl)dicarbamate (impurity-II). Impurity isolation, identification, structure elucidation and the formation of impurities were also discussed. Preparation and structure elucidation of impurity-III were also first reported in this paper. PMID:24333703

  9. Self-pumping impurity control

    DOEpatents

    Brooks, J.N.; Mattas, R.F.

    1983-12-21

    It is an object of the present invention to provide an apparatus for removing impurities from the plasma in a fusion reactor without an external vacuum pumping system. It is also an object of the present invention to provide an apparatus for removing the helium ash from a fusion reactor. It is another object of the present invention to provide an apparatus which removes helium ash and minimizes tritium recycling and inventory.

  10. Impurity diffusion in transition-metal oxides

    SciTech Connect

    Peterson, N.L.

    1982-06-01

    Intrinsic tracer impurity diffusion measurements in ceramic oxides have been primarily confined to CoO, NiO, and Fe/sub 3/O/sub 4/. Tracer impurity diffusion in these materials and TiO/sub 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/sub 2/ whereas chromium ions (a smaller-sized impurity) do not. 60 references, 11 figures.

  11. Gaseous trace impurity analyzer and method

    DOEpatents

    Edwards, Jr., David; Schneider, William

    1980-01-01

    Simple apparatus for analyzing trace impurities in a gas, such as helium or hydrogen, comprises means for drawing a measured volume of the gas as sample into a heated zone. A segregable portion of the zone is then chilled to condense trace impurities in the gas in the chilled portion. The gas sample is evacuated from the heated zone including the chilled portion. Finally, the chilled portion is warmed to vaporize the condensed impurities in the order of their boiling points. As the temperature of the chilled portion rises, pressure will develop in the evacuated, heated zone by the vaporization of an impurity. The temperature at which the pressure increase occurs identifies that impurity and the pressure increase attained until the vaporization of the next impurity causes a further pressure increase is a measure of the quantity of the preceding impurity.

  12. Phase Boundaries of the Pseudogap Anderson Impurity Model

    NASA Astrophysics Data System (ADS)

    Mohammed, Aaron; Chowdhury, Tathagata; Ingersent, Kevin

    2015-03-01

    As the temperature of metals containing dilute concentrations of magnetic impurities reach very low temperatures, a phenomenon known as the Kondo effect takes place in which the resistance increases. This is due to the domination of spin-exchange processes that occur between the electrons of the metal and the electrons of the magnetic impurity near absolute zero. The Anderson model is a quantum impurity model that was developed in the 1960s to explain this phenomenon. It involves a single magnetic impurity tunnel-coupled to the conduction band of a metal. If the conduction band of this system contains a pseudogap, or a power-law decrease in the density of states around the Fermi energy, then quantum phase transitions will occur. The phase boundaries of the pseudogap Anderson impurity model have been previously approximated using poor man's scaling analysis. Here, we focus on using the more accurate numerical renormalization group method to calculate the location of these boundaries. We then compare these numerical results with the predictions derived from the scaling approximations. The development of nanotechnology like quantum dots and STM have rekindled interest in the Kondo effect since it can now be studied within controlled settings. Supported by the NSF REU Grant DMR-1156737: REU Site in Materials Physics at the University of Florida.

  13. Inductively coupled plasma-atomic emission spectroscopy: The determination of trace impurities in uranium hexafluoride

    NASA Astrophysics Data System (ADS)

    Floyd, M. A.; Morrow, R. W.; Farrar, R. B.

    An analytical method has been developed for the determination of trace impurities in high-purity uranium hexafluoride using liquid-liquid extraction of the uranium from the trace impurities followed by analysis with inductively coupled plasma-atomic emission spectroscopy. Detection limits, accuracy, and precision data are presented.

  14. Magnetic impurities on the surface of a topological insulator

    SciTech Connect

    Liu, Qin; Liu, Chao-Xing; Xu, Cenke; Qi, Xiao-Liang; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-25

    The surface states of a topological insulator are described by an emergent relativistic massless Dirac equation in 2+1 dimensions. In contrast to graphene, there is an odd number of Dirac points, and the electron spin is directly coupled to the momentum. We show that a magnetic impurity opens up a local gap and suppresses the local density of states. Furthermore, the Dirac electronic states mediate an RKKY interaction among the magnetic impurities which is always ferromagnetic, whenever the chemical potential lies near the Dirac point. These effects can be directly measured in STM experiments. We also study the case of quenched disorder through a renormalization group analysis.

  15. Quantitative ion-exchange separation of plutonium from impurities

    SciTech Connect

    Pietri, C.E.; Freeman, B.P.; Weiss, J.R.

    1981-09-01

    The methods used at the New Brunswick Laboratory for the quantitative ion exchange separation of plutonium from impurities prior to plutonium assay are described. Other ion exchange separation procedures for impurity determination and for isotopic abundance measurements are given. The primary technique used consists of sorption of plutonium(IV) in 8N HNO/sub 3/ on Dowex-1 anion exchange resin and elution of the purified plutonium with 0.3N HCl-0.01N HF. Other methods consist of the anion exchange separation of plutonium(IV) in 12N HCl and the cation exchange separation of plutonium(III) in 0.2 N HNO/sub 3/. The application of these procedures to the subsequent assay of plutonium, isotopic analysis, and impurity determination is described.

  16. Impurity effects in highly frustrated diamond-lattice antiferromagnets

    NASA Astrophysics Data System (ADS)

    Savary, Lucile; Gull, Emanuel; Trebst, Simon; Alicea, Jason; Bergman, Doron; Balents, Leon

    2011-08-01

    We consider the effects of local impurities in highly frustrated diamond-lattice antiferromagnets, which exhibit large but nonextensive ground-state degeneracies. Such models are appropriate to many A-site magnetic spinels. We argue very generally that sufficiently dilute impurities induce an ordered magnetic ground state and provide a mechanism of degeneracy breaking. The states that are selected can be determined by a “swiss cheese model” analysis, which we demonstrate numerically for a particular impurity model in this case. Moreover, we present criteria for estimating the stability of the resulting ordered phase to a competing frozen (spin glass) one. The results may explain the contrasting finding of frozen and ordered ground states in CoAl2O4 and MnSc2S4, respectively.

  17. Impurity Effects in Highly Frustrated Diamond-Lattice Antiferromagnets

    NASA Astrophysics Data System (ADS)

    Savary, Lucile

    2012-02-01

    We consider the effects of local impurities in highly frustrated diamond lattice antiferromagnets, which exhibit large but non-extensive ground state degeneracies. Such models are appropriate to many A-site magnetic spinels. We argue very generally that sufficiently dilute impurities induce an ordered magnetic ground state, and provide a mechanism of degeneracy breaking. The states which are selected can be determined by a ``swiss cheese model'' analysis, which we demonstrate numerically for a particular impurity model in this case. Moreover, we present criteria for estimating the stability of the resulting ordered phase to a competing frozen (spin glass) one. The results may explain the contrasting finding of frozen and ordered ground states in CoAl2O4 and MnSc2S4, respectively.

  18. Charge dependence of neoclassical and turbulent transport of light impurities on MAST

    NASA Astrophysics Data System (ADS)

    Henderson, S. S.; Garzotti, L.; Casson, F. J.; Dickinson, D.; O'Mullane, M.; Patel, A.; Roach, C. M.; Summers, H. P.; Tanabe, H.; Valovič, M.; the MAST Team

    2015-09-01

    Carbon and nitrogen impurity transport coefficients are determined from gas puff experiments carried out during repeat L-mode discharges on the Mega-Amp Spherical Tokamak (MAST) and compared against a previous analysis of helium impurity transport on MAST. The impurity density profiles are measured on the low-field side of the plasma, therefore this paper focuses on light impurities where the impact of poloidal asymmetries on impurity transport is predicted to be negligible. A weak screening of carbon and nitrogen is found in the plasma core, whereas the helium density profile is peaked over the entire plasma radius. Both carbon and nitrogen experience a diffusivity of the order of 10 m2s-1 and a strong inward convective velocity of ˜40 m s-1 near the plasma edge, and a region of outward convective velocity at mid-radius. The measured impurity transport coefficients are consistent with neoclassical Banana-Plateau predictions within ρ ≤slant 0.4 . Quasi-linear gyrokinetic predictions of the carbon and helium particle flux at two flux surfaces, ρ =0.6 and ρ =0.7 , suggest that trapped electron modes are responsible for the anomalous impurity transport observed in the outer regions of the plasma. The model, combining neoclassical transport with quasi-linear turbulence, is shown to provide reasonable estimates of the impurity transport coefficients and the impurity charge dependence.

  19. Kinetic effects on geodesic acoustic mode from combined collisions and impurities

    SciTech Connect

    Yang, Shangchuan; Xie, Jinlin Liu, Wandong

    2015-04-15

    The dispersion relation for geodesic acoustic mode (GAM) is derived by applying a gyrokinetic model that accounts for the effects from both collisions and impurities. Based on the dispersion relation, an analysis is performed for the non-monotonic behavior of GAM damping versus the characteristic collision rate at various impurity levels. As the effective charge increases, the maximum damping rate is found to shift towards lower collision rates, nearer to the parameter range of a typical tokamak edge plasma. The relative strengths of ion-ion and impurity-induced collision effects, which are illustrated by numerical calculations, are found to be comparable. Impurity-induced collisions help decrease the frequency of GAM, while their effects on the damping rate are non-monotonic, resulting in a weaker total damping in the high collision regime. The results presented suggest considering collision effects as well as impurity effects in GAM analysis.

  20. Impure placebo is a useless concept.

    PubMed

    Louhiala, Pekka; Hemilä, Harri; Puustinen, Raimo

    2015-08-01

    Placebos are allegedly used widely in general practice. Surveys reporting high level usage, however, have combined two categories, 'pure' and 'impure' placebos. The wide use of placebos is explained by the high level usage of impure placebos. In contrast, the prevalence of the use of pure placebos has been low. Traditional pure placebos are clinically ineffective treatments, whereas impure placebos form an ambiguous group of diverse treatments that are not always ineffective. In this paper, we focus on the impure placebo concept and demonstrate problems related to it. We also show that the common examples of impure placebos are not meaningful from the point of view of clinical practice. We conclude that the impure placebo is a scientifically misleading concept and should not be used in scientific or medical literature. The issues behind the concept, however, deserve serious attention in future research. PMID:26215744

  1. Impurity-induced moments in underdoped cuprates

    SciTech Connect

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

    1997-11-01

    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} {ital 1997} {ital The American Physical Society}

  2. Interactions of structural defects with metallic impurities in multicrystalline silicon

    SciTech Connect

    McHugo, S.A.; Thompson, A.C.; Hieslmair, H.

    1997-04-01

    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{sub 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.

  3. Trace organic impurities in gaseous helium

    NASA Technical Reports Server (NTRS)

    Schehl, T. A.

    1973-01-01

    A program to determine trace organic impurities present in helium has been initiated. The impurities were concentrated in a cryogenic trap to permit detection and identification by a gas chromatographic-mass spectrometric technique. Gaseous helium (GHe) exhibited 63 GC flame ionization response peaks. Relative GC peak heights and identifications of 25 major impurities by their mass spectra are given. As an aid to further investigation, identities are proposed for 16 other components, and their mass spectra are given.

  4. Method for detecting trace impurities in gases

    DOEpatents

    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.

  5. Method for detecting trace impurities in gases

    DOEpatents

    Freund, Samuel M.; Maier, II, William B.; Holland, Redus F.; Beattie, Willard H.

    1981-01-01

    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 (.about.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.

  6. Analytical advances in pharmaceutical impurity profiling.

    PubMed

    Holm, René; Elder, David P

    2016-05-25

    Impurities will be present in all drug substances and drug products, i.e. nothing is 100% pure if one looks in enough depth. The current regulatory guidance on impurities accepts this, and for drug products with a dose of less than 2g/day identification of impurities is set at 0.1% levels and above (ICH Q3B(R2), 2006). For some impurities, this is a simple undertaking as generally available analytical techniques can address the prevailing analytical challenges; whereas, for others this may be much more challenging requiring more sophisticated analytical approaches. The present review provides an insight into current development of analytical techniques to investigate and quantify impurities in drug substances and drug products providing discussion of progress particular within the field of chromatography to ensure separation of and quantification of those related impurities. Further, a section is devoted to the identification of classical impurities, but in addition, inorganic (metal residues) and solid state impurities are also discussed. Risk control strategies for pharmaceutical impurities aligned with several of the ICH guidelines, are also discussed. PMID:26690047

  7. On collisional impurity transport in nonaxisymmetric plasmas

    NASA Astrophysics Data System (ADS)

    Mollén, A.; Landreman, M.; Smith, H. M.

    2014-11-01

    The presence of impurity species in magnetic confinement fusion devices leads to radiation losses and plasma dilution. Thus it is important to analyze impurity dynamics, and search for means to control them. In stellarator plasmas the neoclassical ambipolar radial electric field often points radially inwards (referred to as the ion root regime), causing impurities to accumulate in the core. This can limit the performance of nonaxisymmetric devices. In the present work we analyze neoclassical impurity transport in stellarator plasmas using a recently developed continuum drift-kinetic solver, the SFINCS code (the Stellarator Fokker- Planck Iterative Neoclassical Conservative Solver). The study is performed for a case close to the edge of W7-X using the standard configuration magnetic geometry. We investigate the sensitivity of impurity transport to impurity charge, main species density and temperature gradients, as well as ion temperature. At the studied radial location we find that the neoclassical impurity peaking factor can be very large, particularly for high-Z impurities. The ambipolar radial electric field is in the ion root regime, and impurity accumulation can thus be expected. The accumulation is strengthened by the large main species density and temperature gradients. Moreover we find that the size of the bootstrap current is affected by the value of the plasma effective charge, suggesting that employing a realistic ion composition can be important when calculating the bootstrap current.

  8. Detection of Carbon Nanotubes in Indoor Workplaces Using Elemental Impurities.

    PubMed

    Rasmussen, Pat E; Avramescu, Mary-Luyza; Jayawardene, Innocent; Gardner, H David

    2015-11-01

    This study investigated three area sampling approaches for using metal impurities in carbon nanotubes (CNTs) to identify CNT releases in workplace environments: air concentrations (μg/m3), surface loadings (μg/cm2), and passive deposition rates (μg/m2/h). Correlations between metal impurities and CNTs were evaluated by collecting simultaneous colocated area samples for thermal-optical analysis (for CNTs) and ICP-MS analysis (for metals) in a CNT manufacturing facility. CNTs correlated strongly with Co (residual catalyst) and Ni (impurity) in floor surface loadings, and with Co in passive deposition samples. Interpretation of elemental ratios (Co/Fe) assisted in distinguishing among CNT and non-CNT sources of contamination. Stable isotopes of Pb impurities were useful for identifying aerosolized CNTs in the workplace environment of a downstream user, as CNTs from different manufacturers each had distinctive Pb isotope signatures. Pb isotopes were not useful for identifying CNT releases within a CNT manufacturing environment, however, because the CNT signature reflected the indoor background signature. CNT manufacturing companies and downstream users of CNTs will benefit from the availability of alternative and complementary strategies for identifying the presence/absence of CNTs in the workplace and for monitoring the effectiveness of control measures. PMID:26451679

  9. Identification and Characterization of Potential Impurities in Raloxifene Hydrochloride

    PubMed Central

    Reddy, Reguri Buchi; Goud, Thirumani Venkateshwar; Nagamani, Nagabushanam; Kumar, Nutakki Pavan; Alagudurai, Anandan; Murugan, Raman; Parthasarathy, Kannabiran; Karthikeyan, Vinayagam; Balaji, Perumal

    2012-01-01

    During the synthesis of the bulk drug Raloxifene hydrochloride, eight impurities were observed, four of which were found to be new. All of the impurities were detected using the gradient high performance liquid chromatographic (HPLC) method, whose area percentages ranged from 0.05 to 0.1%. LCMS was performed to identify the mass number of these impurities, and a systematic study was carried out to characterize them. These impurities were synthesized and characterized by spectral data, subjected to co-injection in HPLC, and were found to be matching with the impurities present in the sample. Based on their spectral data (IR, NMR, and Mass), these impurities were characterized as Raloxifene-N-Oxide [Impurity: 1]; EP impurity A [Impurity: 2]; EP impurity B [Impurity: 3]; Raloxifene Dimer [Impurity: 4]; HABT (6-Acetoxy-2-[4-hydroxyphenyl]-1-benzothiophene or 6-Hydroxy-2-[4-acetoxyphenyl]-1-benzothiophene) [Impurity: 5]; PEBE (Methyl[4-[2-(piperidin-1-yl)ethoxy

  10. Spectroscopic characterization and quantitative determination of atorvastatin calcium impurities by novel HPLC method

    NASA Astrophysics Data System (ADS)

    Gupta, Lokesh Kumar

    2012-11-01

    Seven process related impurities were identified by LC-MS in the atorvastatin calcium drug substance. These impurities were identified by LC-MS. The structure of impurities was confirmed by modern spectroscopic techniques like 1H NMR and IR and physicochemical studies conducted by using synthesized authentic reference compounds. The synthesized reference samples of the impurity compounds were used for the quantitative HPLC determination. These impurities were detected by newly developed gradient, reverse phase high performance liquid chromatographic (HPLC) method. The system suitability of HPLC analysis established the validity of the separation. The analytical method was validated according to International Conference of Harmonization (ICH) with respect to specificity, precision, accuracy, linearity, robustness and stability of analytical solutions to demonstrate the power of newly developed HPLC method.

  11. Eliminating Impurity Traps in the Silane Process

    NASA Technical Reports Server (NTRS)

    Coleman, L. M.

    1982-01-01

    Redistribution reaction section of silane process progressively separates heavier parts of chlorosilane feedstock until light silane product is available for pyrolysis. Small amount of liquid containing impurities is withdrawn from processing stages in which trapping occurs and passed to earlier processing stage in which impurities tend to be removed via chemical reactions.

  12. Highly efficient, selective, sensitive and stability indicating RP-HPLC-UV method for the quantitative determination of potential impurities and characterization of four novel impurities in eslicarbazepine acetate active pharmaceutical ingredient by LC/ESI-IT/MS/MS.

    PubMed

    Thomas, Saji; Bharti, Amber; Maddhesia, Pawan Kumar; Shandilya, Sanjeev; Agarwal, Ashutosh; Dharamvir; Biswas, Sujay; Bhansal, Vikas; Gupta, Ashish Kumar; Tewari, Praveen Kumar; Mathela, Chandra S

    2012-03-01

    A novel, sensitive, selective and stability indicating LC-UV method was developed for the determination of potential impurities of eslicarbazepine acetate. High performance liquid chromatographic investigation of eslicarbazepine acetate laboratory sample revealed the presence of several impurities. Three impurities were characterized rapidly and four impurities were found to be unknown. The unknown impurities were identified by liquid chromatography coupled with electrospray ionization, ion trap mass spectrometry (LC/ESI-IT/MS/MS). Structural confirmation of these impurities was unambiguously carried out by synthesis followed by characterization using nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (FT-IR) and mass spectrometry (MS). Based on the spectroscopic, spectrometric and elemental analysis data unknown impurities were characterized as 5-acetyl-5,11-dihydro-10H-dibenzo [b,f]azepin-10-one, N-acetyl-5H-dibenzo[b,f]azepine-5-carboxamide, 5-acetyl-10,11-dihydro-5H-dibenzo[b,f]azepin-10-yl acetate and 5-acetyl-5H-dibenzo[b,f]azepin-10-yl acetate. The newly developed LC-UV method was validated according to ICH guidelines considering eleven potential impurities and four new impurities to demonstrate specificity, precision, linearity, accuracy and stability indicating nature of the method. The newly developed method was found to be highly efficient, selective, sensitive and stability indicating. A plausible pathway for the formation of four new impurities is proposed. PMID:22178334

  13. Direct Visualization of an Impurity Depletion Zone

    NASA Technical Reports Server (NTRS)

    Chernov, Alex A.; Garcia-Ruiz, Juan Ma; Thomas, Bill R.

    2000-01-01

    When a crystal incorporates more impurity per unit of its volume than the impurity concentration in solution, the solution in vicinity of the growing crystal is depleted with respect to the impurity I,2. With a stagnant solution, e. g. in microgravity or gels, an impurity depletion zone expands as the crystal grows and results in greater purity in most of the outer portion of the crystal than in the core. Crystallization in gel provides an opportunity to mimic microgravity conditions and visualize the impurity depletion zone. Colorless, transparent apoferritin (M congruent to 450 KDa) crystals were grown in the presence of red holoferritin dimer as a microheterogeneous impurity (M congruent to 900 KDa) within agarose gel by counterdiffusion with Cd(2+) precipitant. Preferential trapping of dimers, (distribution coefficient K = 4 (exp 1,2)) results in weaker red color around the crystals grown in the left tube in the figure as compared to the control middle tube without crystals. The left and the middle tubes contain colored ferritin dimers, the right tube contains colored trimers. The meniscus in the left tube separate gel (below) and liquid solution containing Cd(2+) (above). Similar solutions, though without precipitants, were present on top of the middle and right tube allowing diffusion of dimers and trimers. The area of weaker color intensity around crystals directly demonstrates overlapped impurity depletion zones.

  14. Paramagnetic Attraction of Impurity-Helium Solids

    NASA Technical Reports Server (NTRS)

    Bernard, E. P.; Boltnev, R. E.; Khmelenko, V. V.; Lee, D. M.

    2003-01-01

    Impurity-helium solids are formed when a mixture of impurity and helium gases enters a volume of superfluid helium. Typical choices of impurity gas are hydrogen deuteride, deuterium, nitrogen, neon and argon, or a mixture of these. These solids consist of individual impurity atoms and molecules as well as clusters of impurity atoms and molecules covered with layers of solidified helium. The clusters have an imperfect crystalline structure and diameters ranging up to 90 angstroms, depending somewhat on the choice of impurity. Immediately following formation the clusters aggregate into loosely connected porous solids that are submerged in and completely permeated by the liquid helium. Im-He solids are extremely effective at stabilizing high concentrations of free radicals, which can be introduced by applying a high power RF dis- charge to the impurity gas mixture just before it strikes the super fluid helium. Average concentrations of 10(exp 19) nitrogen atoms/cc and 5 x 10(exp 18) deuterium atoms/cc can be achieved this way. It shows a typical sample formed from a mixture of atomic and molecular hydrogen and deuterium. It shows typical sample formed from atomic and molecular nitrogen. Much of the stability of Im-He solids is attributed to their very large surface area to volume ratio and their permeation by super fluid helium. Heat resulting from a chance meeting and recombination of free radicals is quickly dissipated by the super fluid helium instead of thermally promoting the diffusion of other nearby free radicals.

  15. Quantifying Main Trends in Lysozyme Nucleation: The Effects of Precipitant Concentration, Supersaturation and Impurities

    NASA Technical Reports Server (NTRS)

    Burke, Michael W.; Leardi, Riccardo; Judge, Russell A.; Pusey, Marc L.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Full factorial experimental design incorporating multi-linear regression analysis of the experimental data allows quick identification of main trends and effects using a limited number of experiments. In this study these techniques were employed to identify the effect of precipitant concentration, supersaturation, and the presence of an impurity, the physiological lysozyme dimer, on the nucleation rate and crystal dimensions of the tetragonal forin of chicken egg white lysozyme. Decreasing precipitant concentration, increasing supers aturation, and increasing impurity, were found to increase crystal numbers. The crystal axial ratio decreased with increasing precipitant concentration, independent of impurity.

  16. Electronic properties of substitutional impurities in InGaN monolayer quantum wells

    SciTech Connect

    Alfieri, G.; Tsutsumi, T.; Micheletto, R.

    2015-05-11

    InGaN alloys and, in particular, InGaN monolayer quantum wells (MLQWs) are attracting an increasing amount of interest for opto-electronic applications. Impurities, incorporated during growth, can introduce electronic states that can degrade the performance of such devices. For this reason, we present a density functional and group theoretical study of the electronic properties of C, H, or O impurities in an InGaN MLQW. Analysis of the formation energy and symmetry reveals that these impurities are mostly donors and can be held accountable for the reported degradation of InGaN-based devices.

  17. Al and Zn Impurity Diffusion in Binary and Ternary Magnesium Solid-Solutions

    SciTech Connect

    Kammerer, Catherine; Kulkarni, Nagraj S; Warmack, Robert J Bruce; Sohn, Yong Ho

    2014-01-01

    Magnesium alloys are considered for implementation into structural components where energy-efficiency and light-weighting are important. Two of the most common alloying elements in magnesium alloys are Aluminum and Zinc. The present work examines impurity diffusion coefficients of Al and Zn in Mg(Zn) and Mg(Al) binary solid solutions, respectively. Experimental investigation is carried out with ternary diffusion couples with polycrystalline alloys. Concentration profiles were measured by electron microprobe micro-analysis and the impurity diffusion coefficients were determined by the Hall Method. Results of Al and Zn impurity diffusion in Mg solid solutions are reported, and examined as a function of composition of Mg solid solution.

  18. An introduction to blocked impurity band detectors

    NASA Technical Reports Server (NTRS)

    Geist, Jon

    1988-01-01

    Blocked impurity band detectors fabricated using standard silicon technologies offer the possibility of combining high sensitivity and high accuracy in a single detector operating in a low background environment. The solid state photomultiplier described by Petroff et al., which is a new type of blocked impurity band detector, offers even higher sensitivity as well as operation in the visible spectral region. The principle of operation and possible application of blocked impurity band detectors for stellar seismology and the search for extra-solar planets are described.

  19. Multiple magnetic impurities on surfaces: Scattering and quasiparticle interference

    NASA Astrophysics Data System (ADS)

    Mitchell, Andrew K.; Derry, Philip G.; Logan, David E.

    2015-06-01

    We study systems of multiple interacting quantum impurities deposited on a metallic surface in a three-dimensional host. For the real-space two-impurity problem, using numerical renormalization group calculations, a rich range of behavior is shown to arise due to the interplay between Kondo physics and effective Ruderman-Kittel-Kasuya-Yosida interactions—provided the impurity separation is small. Such calculations allow identification of the minimum impurity separation required for a description in terms of independent impurities, and thereby the onset of the "dilute-impurity limit" in many-impurity systems. A "dilute-cluster" limit is also identified in systems with higher impurity density, where interimpurity interactions are important only within independent clusters. We calculate the quasiparticle interference due to two and many impurities, and explore the consequences of the independent impurity and cluster paradigms. Our results provide a framework to investigate the effects of disorder due to interacting impurities at experimentally relevant surface coverages.

  20. Heroin impurity profiling: trends throughout a decade of experimenting.

    PubMed

    Dams, R; Benijts, T; Lambert, W E; Massart, D L; De Leenheer, A P

    2001-12-01

    Heroin is still one of the most frequently abused drugs of today. All over the world, law enforcement agencies try to eradicate the illicit production and trafficking of this potent and highly addictive narcotic. To this aim, important information is provided by physical and chemical toxicological analysis of confiscated samples, with special attention for the identification and the quantification of minor components, such as the impurities related to the origin and manufacturing. By combining these data complex characterisations, i.e. impurity profiles, chemical signatures or fingerprints, can be obtained and used for comparative analysis. This review focuses on heroin impurity profiling during the 1990s, proclaimed by the United Nations as the 'Decade for Eradicating Drug Abuse'. Special attention will be given to the new trends in analytical techniques as well as in data handling strategies, so called chemometrics, to produce these profiles. The latter can be used in comparative analysis of seized heroin samples for tactical (batch-to-batch comparison) and strategic (origin determination) intelligence purposes. PMID:11728732

  1. Determination of synthesis method of ecstasy based on the basic impurities.

    PubMed

    Swist, M; Wilamowski, J; Parczewski, A

    2005-09-10

    MDMA was prepared by five different synthesis routes, i.e. by dissolving metal reduction (Al/Hg), cyanoborohydride reduction (NaBH(3)CN), borohydride reduction in low temperature (NaBH(4)), Leuckart reaction and safrole bromination. MDP-2-P was prepared by two different synthesis methods, i.e. by isosafrole oxidation and MDP-2-nitropropene reduction. Each of the synthesis routes was repeated three times in order to establish variation in qualitative composition of route specific impurities between different batches. The analysis of impurities in MDP-2-nitropropene, MDP-2-P, bromosafrole and MDMA was performed with GC-MS. GC/MS was used also in the analysis of impurities in starting materials: safrole, isosafrole and piperonal. As a result of our study the way of determination of MDMA synthesis route determination based on qualitative composition of impurities is proposed. PMID:15978342

  2. APPLICATION OF COLUMN EXTRACTION METHOD FOR IMPURITIES ANALYSIS ON HB-LINE PLUTONIUM OXIDE IN SUPPORT OF MOX FEED PRODUCT SPECIFICATIONS

    SciTech Connect

    Jones, M.; Diprete, D.; Wiedenman, B.

    2012-03-20

    The current mission at H-Canyon involves the dissolution of an Alternate Feedstocks 2 (AFS-2) inventory that contains plutonium metal. Once dissolved, HB-Line is tasked with purifying the plutonium solution via anion exchange, precipitating the Pu as oxalate, and calcining to form plutonium oxide (PuO{sub 2}). The PuO{sub 2} will provide feed product for the Mixed Oxide (MOX) Fuel Fabrication Facility, and the anion exchange raffinate will be transferred to H-Canyon. The results presented in this report document the potential success of the RE resin column extraction application on highly concentrated Pu samples to meet MOX feed product specifications. The original 'Hearts Cut' sample required a 10000x dilution to limit instrument drift on the ICP-MS method. The instrument dilution factors improved to 125x and 250x for the sample raffinate and sample eluent, respectively. As noted in the introduction, the significantly lower dilutions help to drop the total MRL for the analyte. Although the spike recoveries were half of expected in the eluent for several key elements, they were between 94-98% after Nd tracer correction. It is seen that the lower ICD limit requirements for the rare earths are attainable because of less dilution. Especially important is the extremely low Ga limit at 0.12 {mu}g/g Pu; an ICP-MS method is now available to accomplish this task on the sample raffinate. While B and V meet the column A limits, further development is needed to meet the column B limits. Even though V remained on the RE resin column, an analysis method is ready for investigation on the ICP-MS, but it does not mean that V cannot be measured on the ICP-ES at a low dilution to meet the column B limits. Furthermore, this column method can be applicable for ICP-ES as shown in Table 3-2, in that it trims the sample of Pu, decreasing and sometimes eliminating Pu spectral interferences.

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

    NASA Astrophysics Data System (ADS)

    Kumar, S. T. A.; Den Hartog, D. J.; Mirnov, V. V.; Caspary, K. J.; Magee, R. M.; Brower, D. L.; Chapman, B. E.; Craig, D.; Ding, W. X.; Eilerman, S.; Fiksel, G.; Lin, L.; Nornberg, M.; Parke, E.; Reusch, J. A.; Sarff, J. S.

    2012-05-01

    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.

  4. Impurity induced resistivity upturns in underdoped cuprates

    NASA Astrophysics Data System (ADS)

    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.

  5. Influence of magnetic shear on impurity transport

    SciTech Connect

    Nordman, H.; Fueloep, T.; Candy, J.; Strand, P.; Weiland, J.

    2007-05-15

    The magnetic shear dependence of impurity transport in tokamaks is studied using a quasilinear fluid model for ion temperature gradient (ITG) and trapped electron (TE) mode driven turbulence in the collisionless limit and the results are compared with nonlinear gyrokinetic results using GYRO [J. Candy and R. E. Waltz, J. Comput. Phys 186, 545 (2003)]. It is shown that the impurity transport is sensitive to the magnetic shear, in particular for weak, negative, and large positive shear where a strong reduction of the effective impurity diffusivity is obtained. The fluid and gyrokinetic results are in qualitative agreement, with the gyrokinetic diffusivities typically a factor 2 larger than the fluid diffusivities. The steady state impurity profiles in source-free plasmas are found to be considerably less peaked than the electron density profiles for moderate shear. Comparisons between anomalous and neoclassical transport predictions are performed for ITER-like profiles [R. Aymar, P. Barabaschi, and Y. Shimomura, Plasma Phys. Controlled Fusion 44, 519 (2002)].

  6. DIVIMP Modeling of Impurity Transport in EAST

    NASA Astrophysics Data System (ADS)

    Wang, Fuqiong; Chen, Yiping; Hu, Liqun

    2014-07-01

    Simulations of carbon impurity transport in SOL/divertor plasmas with Ohmic heating on EAST tokamak were performed using the two-dimensional (2D) Monte Carlo impurity transport code DIVIMP. The background plasmas for DIVIMP simulations were externally taken from B2.5/Eirene calculation. Besides the basic output of DIVIMP, the 2D density distributions of the carbon impurity with different ionization states and neutral carbon atoms were obtained, the 2D distributions of CII and CIII emissivities from C+1 and C+2 radiation respectively were also calculated. Comparison between the measured and calculated CIII emissivities showed favorable agreement, indicating that the impurity physics transport models, as implemented in the DIVIMP code, are suitable for the EAST tokamak plasma condition.

  7. Numerical Studies of Impurities in Fusion Plasmas

    DOE R&D Accomplishments Database

    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.

  8. Single impurity in ultracold Fermi superfluids

    SciTech Connect

    Jiang Lei; Baksmaty, Leslie O.; Pu, Han; Hu Hui; Chen Yan

    2011-06-15

    The role of impurities as experimental probes in the detection of quantum material properties is well appreciated. Here we study the effect of a single classical magnetic impurity in trapped ultracold Fermi superfluids. Depending on its shape and strength, a magnetic impurity can induce single or multiple midgap bound states in a superfluid Fermi gas. The multiple midgap states could coincide with the development of a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase within the superfluid. As an analog of the scanning tunneling microsope, we propose a modified rf spectroscopic method to measure the local density of states which can be employed to detect these states and other quantum phases of cold atoms. A key result of our self-consistent Bogoliubov-de Gennes calculations is that a magnetic impurity can controllably induce an FFLO state at currently accessible experimental parameters.

  9. Role of impurities in fusion plasmas

    SciTech Connect

    Tokar, M. Z.

    2008-10-15

    The role of impurity at the plasma edge of fusion devices is considered by analysing the influence on radiation losses and anomalous transport of particle and energy. The conditions critical for the development of radiative instabilities leading to the formation of detachment and MARFE and those necessary for the creation of a stable radiating edge, protecting the wall elements from intensive heat loads, are analyzed. Mechanisms responsible for anomalous transport suppression with impurity seeding are elucidated.

  10. Precipitating Chromium Impurities in Silicon Wafers

    NASA Technical Reports Server (NTRS)

    Salama, A. M.

    1982-01-01

    Two new treatments for silicon wafers improve solar-cell conversion efficiency by precipitating electrically-active chromium impurities. One method is simple heat treatment. Other involves laser-induced damage followed by similar heat treatment. Chromium is one impurity of concern in metallurgical-grade silicon for solar cells. In new treatment, chromium active centers are made electrically inactive by precipitating chromium from solid solution, enabling use of lower grade, lower cost silicon in cell manufacture.

  11. Ultrashort pulses in graphene with Coulomb impurities

    NASA Astrophysics Data System (ADS)

    Konobeeva, N. N.; Belonenko, M. B.

    2016-06-01

    We have investigated the propagation of an electromagnetic field in graphene with impurities, including the two-dimensional case. The spectrum of electrons for the graphene subsystem is taken from a model that takes into account Coulomb impurities. Based on Maxwell's equations, we have obtained an effective equation for the vector potential of the electromagnetic field. It has been revealed that the pulse shape depends on free parameters.

  12. Method of removing phosphorus impurities from yellowcake

    SciTech Connect

    Brown, R.A.; Winkley, D.C.

    1983-04-05

    PhospHorus impurities are removed from yellowcake by dissolving it in hydrochloric or sulfuric acid to a U/sub 3/O/sub 88/ assay of at least 150 g/l at a pH of 2; precipitating uranium peroxide W hydrogen peroxide while keeping the pH between 2.2 and 2.6 and recovering the uranium peroxide from the phosphorus impurities remaining in solution.

  13. Scattering theory and ground-state energy of Dirac fermions in graphene with two Coulomb impurities

    NASA Astrophysics Data System (ADS)

    Klöpfer, Denis; De Martino, Alessandro; Matrasulov, Davron U.; Egger, Reinhold

    2014-08-01

    We study the physics of Dirac fermions in a gapped graphene monolayer containing two Coulomb impurities. For the case of equal impurity charges, we discuss the ground-state energy using the linear combination of atomic orbitals (LCAO) approach. For opposite charges of the Coulomb centers, an electric dipole potential results at large distances. We provide a nonperturbative analysis of the corresponding low-energy scattering problem.

  14. Impurities and evaluation of induced activity of SiC f/SiC composites

    NASA Astrophysics Data System (ADS)

    Stamatelatos, I. E.; Mergia, K.; Lefkopoulos, G.; Forrest, R.

    2004-01-01

    The impurities in industrially produced SiC f/SiC composites were determined by neutron activation analysis. The evaluation of the induced activity based on the atomic composition was made using the European Activation System (EASY-2001) for a fusion power plant first wall. The effect of trace element impurities on contact gamma dose rate is discussed and the trace elements of radiological importance are identified.

  15. Mechanisms of impurity diffusion in rutile

    SciTech Connect

    Peterson, N.L.; Sasaki, J.

    1984-01-01

    Tracer diffusion of /sup 46/Sc, /sup 51/Cr, /sup 54/Mn, /sup 59/Fe, /sup 60/Co, /sup 63/Ni, and /sup 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/sub 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.

  16. P-type Modified Electrode Germanium Detector Impurity Profiles

    NASA Astrophysics Data System (ADS)

    Kephart, Jeremy

    2008-04-01

    Germanium detectors with unprecedented capabilities are needed for detecting ultra-rare events in future neutrinoless double-beta decay experiments, searches for dark matter, environmental monitoring programs, national security applications, and potentially neutrino astrophysics. An ideal detector would combine ultra-low background capabilities, minimal electronic instrumentation, extremely low energy threshold, and the ability to perform event reconstruction to determine the interaction type or the spatial distribution of ionization following an interaction. A germanium detector with a special, very low capacitance, contact geometry and presumably a deliberately contrived impurity profile could provide all these capabilities. We present an analysis of the detector impurity concentration profiles and their impact on the depletion voltage, capacitance and charge collection times for such detectors.

  17. Enhanced Antiferromagnetic Exchange between Magnetic Impurities in a Superconducting Host

    NASA Astrophysics Data System (ADS)

    Yao, N. Y.; Glazman, L. I.; Demler, E. A.; Lukin, M. D.; Sau, J. D.

    2014-08-01

    It is generally believed that superconductivity only weakly affects the indirect exchange between magnetic impurities. If the distance r between impurities is smaller than the superconducting coherence length (r≲ξ), this exchange is thought to be dominated by Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions, identical to the those in a normal metallic host. This perception is based on a perturbative treatment of the exchange interaction. Here, we provide a nonperturbative analysis and demonstrate that the presence of Yu-Shiba-Rusinov bound states induces a strong 1/r2 antiferromagnetic interaction that can dominate over conventional RKKY even at distances significantly smaller than the coherence length (r≪ξ). Experimental signatures, implications, and applications are discussed.

  18. Segregation Coefficients of Impurities in Selenium by Zone Refining

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Sha, Yi-Gao

    1998-01-01

    The purification of Se by zone refining process was studied. The impurity solute levels along the length of a zone-refined Se sample were measured by spark source mass spectrographic analysis. By comparing the experimental concentration levels with theoretical curves the segregation coefficient, defined as the ratio of equilibrium concentration of a given solute in the solid to that in the liquid, k = x(sub s)/x(sub l) for most of the impurities in Se are found to be close to unity, i.e., between 0.85 and 1.15, with the k value for Si, Zn, Fe, Na and Al greater than 1 and that for S, Cl, Ca, P, As, Mn and Cr less than 1. This implies that a large number of passes is needed for the successful implementation of zone refining in the purification of Se.

  19. Impurity Particle Transport in High Confinement Regimes Without ELMs on DIII-D

    NASA Astrophysics Data System (ADS)

    Grierson, B. A.

    2014-10-01

    Recent experiments on DIII-D using trace levels of fluorine gas injection have shown that high confinement regimes without ELMs can achieve rapid transport of impurity ions. Much attention has recently been given to regimes with H-mode energy confinement without edge-localized modes (ELMs), accessed either through Resonant Magnetic Perturbations (RMPs) or MHD such as edge harmonic oscillations or quasi-coherent edge oscillations. Experiments on DIII-D have used gas puffing of trace levels of fluorine to introduce this fully-stripped, non-intrinsic and non-recycling impurity that can be easily measured with charge-exchange recombination spectroscopy. Trace fluorine is used because the time-history of the fluorine density profile permits direct extraction of the confinement time, particle diffusivity and convective velocity without relying on atomic modeling or assumptions about the source recycling. Results indicate impurity accumulation is more pronounced in RMP ELM suppressed plasmas with a pure n = 3 spectrum compared with mixed n = 1 and n = 3 RMP fields with reduced number of control coils. In cases where strong central carbon impurity accumulation occurs, trace fluorine analysis reveals a strong inward impurity pinch. Conversely, in plasmas with weak central carbon accumulation, the fluorine pinch is significantly lower. These measurements of impurity influx are consistent with TGLF modeling of the ELM-suppressed phase of the discharge revealing that strong impurity influx occurs when the ratio V/D is between -1 to -3. In this work, the dependencies of impurity transport on local driving gradients will be presented, and the means of increasing the impurity diffusion to recover high purity plasmas will be discussed providing a basis for achieving low-dilution, stationary ELM-free operation in ITER and future devices. Supported by the US DOE under DE-AC0-09CH11466 and DE-FC02-05ER54698.

  20. Dynamics of impurities in ultracold Bose gas

    NASA Astrophysics Data System (ADS)

    Shchadilova, Yulia; Grusdt, Fabian; Rubtsov, Alexey; Demler, Eugene

    2015-05-01

    A system of an impurity immersed in a Bose-Einstein condensate (BEC) exhibits the polaronic effect, which is known to be an ubiquitous phenomenon in a wide range of physical systems including semiconductors, doped Mott insulators, and high-Tc superconductors. Recent analysis of the BEC-polaron problem showed that existing analytical approaches do not provide reliable results in the experimentally relevant range of parameters when tested against Monte Carlo (MC) simulations. In this contribution we demonstrate that the description of polarons at finite momentum can be done by employing an analytical class of wavefunctions based on the correlated Gaussian ansatz (CGWs). We show that CGWs show excellent agreement with known MC results for the polaron binding energy for a wide range of interactions. We discuss the properties of the polarons and atomic mixtures in systems of ultracold atoms in which polaronic effects can be observed with current experimental technology. Our CGWs predicts a specific pattern of correlations between host atoms that can be measured in time-of-flight experiments. Department of Physics, Harvard University.

  1. Turbulent and neoclassical impurity transport in tokamak plasmas

    SciTech Connect

    Fueloep, T.; Nordman, H.

    2009-03-15

    Impurity particle transport in tokamaks is studied using an electrostatic fluid model for main ion and impurity temperature gradient (ITG) mode and trapped electron (TE) mode turbulence in the collisionless limit and neoclassical theory. The impurity flux and impurity density peaking factor obtained from a self-consistent treatment of impurity transport are compared and contrasted with the results of the often used trace impurity approximation. Comparisons between trace and self-consistent turbulent impurity transport are performed for ITER-like profiles. It is shown that for small impurity concentrations the trace impurity limit is adequate if the plasma is dominated by ITG turbulence. However, in case of TE mode dominated plasmas the contribution from impurity modes may be significant, and therefore a self-consistent treatment may be needed.

  2. Investigating the Effect of Impurities on Macromolecule Crystal Growth in Microgravity

    NASA Technical Reports Server (NTRS)

    Snell, Edward H.; Judge, Russell A.; Crawford, Lisa; Forsythe, Elizabeth L.; Pusey, Marc L.; Sportiello, Michael; Todd, Paul; Bellamy, Henry; Lovelace, Jeff; Cassanto, John M.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Chicken egg-white lysozyme (CEWL) crystals were grown in microgravity and on the ground in the presence of various amounts of a naturally occurring lysozyme dimer impurity. No significant favorable differences in impurity incorporation between microgravity and ground crystal samples were observed. At low impurity concentration the microgravity crystals preferentially incorporated the dimer. The presence of the dimer in the crystallization solutions in microgravity reduced crystal size, increased mosaicity and reduced the signal to noise ratio of the X-ray data. Microgravity samples proved more sensitive to impurity. Accurate indexing of the reflections proved critical to the X-ray analysis. The largest crystals with the best X-ray diffraction properties were grown from pure solution in microgravity.

  3. Impurity segregation in zone-refined precursors for crystalline halide scintillators

    NASA Astrophysics Data System (ADS)

    Swider, S.; Lam, S.; Motakef, S.; Donohoe, E.; Coers, L.; Taylor, S.; Spencer, S.

    2015-06-01

    Successful growth of halide scintillator crystals depends on a supply of ultra-high purity (UHP) precursor materials. Metallic interstitials and substitutions may provide traps that quench luminescence. Oxygen impurities can create competing compounds within a matrix, such as oxyhalides, that disrupt crystallinity and nucleate cracks. Using mass spectroscopy and oxygen combustion analysis, we analyzed impurities in SrI2, EuI2, and YCl3 precursors before and after zone refining. The data show most alkali and alkali earth impurities segregated easily. However, with the exception of iron, many transition metals were incorporated into the solid. Reliable oxygen measurements proved difficult to achieve. Additional oxygen was measured in nitrates and sulfates, via ion chromatography. Zone refining reduced the overall impurity content, but levels remained above a 10 ppm target.

  4. Quantitative assessment of cumulative carcinogenic risk for multiple genotoxic impurities in a new drug substance.

    PubMed

    Bercu, Joel P; Hoffman, Wherly P; Lee, Cindy; Ness, Daniel K

    2008-08-01

    In pharmaceutical development, significant effort is made to minimize the carcinogenic potential of new drug substances (NDS). This involves appropriate genotoxicity and carcinogenicity testing of the NDS, and understanding the genotoxic potential of its impurities. Current available guidance recommends the use of the threshold of toxicological concern (TTC) for a single impurity where mutagenicity but no carcinogenicity information exists. Despite best efforts, the presence of more than one genotoxic impurity in an NDS may occur at trace levels. This paper repeats the analysis performed by others for a single genotoxic compound, but also uses statistical simulations to assess the impact on cancer risk for a mixture of genotoxic compounds. In summary, with the addition of multiple impurities all controlled to the TTC, an increase in cancer risk was observed. This increase is relatively small when considering the conservative assumptions of the TTC. If structurally similar compounds had an assumed strong correlation (+/-10-fold from the first randomly selected impurity) in cancer potency, the resulting cancer risk was not negatively impacted. Findings based on probabilistic analysis here can be very useful in making appropriate decisions about risk management of multiple genotoxic impurities measured in the final drug substance. PMID:18550240

  5. Impurity profiling to match a nerve agent to its precursor source for chemical forensics applications.

    PubMed

    Fraga, Carlos G; Acosta, Gabriel A Pérez; Crenshaw, Michael D; Wallace, Krys; Mong, Gary M; Colburn, Heather A

    2011-12-15

    Chemical forensics is a developing field that aims to attribute a chemical (or mixture) of interest to its source by the analysis of the chemical itself or associated material constituents. Herein, for the first time, trace impurities detected by gas chromatography/mass spectrometry and originating from a chemical precursor were used to match a synthesized nerve agent to its precursor source. Specifically, six batches of sarin (GB, isopropyl methylphosphonofluoridate) and its intermediate methylphosphonic difluoride (DF) were synthesized from two commercial stocks of 97% pure methylphosphonic dichloride (DC); the GB and DF were then matched by impurity profiling to their DC stocks from a collection of five possible stocks. Source matching was objectively demonstrated through the grouping by hierarchal cluster analysis of the GB and DF synthetic batches with their respective DC precursor stocks based solely upon the impurities previously detected in five DC stocks. This was possible because each tested DC stock had a unique impurity profile that had 57% to 88% of its impurities persisting through product synthesis, decontamination, and sample preparation. This work forms a basis for the use of impurity profiling to help find and prosecute perpetrators of chemical attacks. PMID:22040126

  6. Anderson metal-insulator transitions with classical magnetic impurities

    SciTech Connect

    Jung, Daniel; Kettemann, Stefan

    2014-08-20

    We study the effects of classical magnetic impurities on the Anderson metal-insulator transition (AMIT) numerically. In particular we find that while a finite concentration of Ising impurities lowers the critical value of the site-diagonal disorder amplitude W{sub c}, in the presence of Heisenberg impurities, W{sub c} is first increased with increasing exchange coupling strength J due to time-reversal symmetry breaking. The resulting scaling with J is compared to analytical predictions by Wegner [1]. The results are obtained numerically, based on a finite-size scaling procedure for the typical density of states [2], which is the geometric average of the local density of states. The latter can efficiently be calculated using the kernel polynomial method [3]. Although still suffering from methodical shortcomings, our method proves to deliver results close to established results for the orthogonal symmetry class [4]. We extend previous approaches [5] by combining the KPM with a finite-size scaling analysis. We also discuss the relevance of our findings for systems like phosphor-doped silicon (Si:P), which are known to exhibit a quantum phase transition from metal to insulator driven by the interplay of both interaction and disorder, accompanied by the presence of a finite concentration of magnetic moments [6].

  7. Anderson metal-insulator transitions with classical magnetic impurities

    NASA Astrophysics Data System (ADS)

    Jung, Daniel; Kettemann, Stefan

    2014-08-01

    We study the effects of classical magnetic impurities on the Anderson metal-insulator transition (AMIT) numerically. In particular we find that while a finite concentration of Ising impurities lowers the critical value of the site-diagonal disorder amplitude Wc, in the presence of Heisenberg impurities, Wc is first increased with increasing exchange coupling strength J due to time-reversal symmetry breaking. The resulting scaling with J is compared to analytical predictions by Wegner [1]. The results are obtained numerically, based on a finite-size scaling procedure for the typical density of states [2], which is the geometric average of the local density of states. The latter can efficiently be calculated using the kernel polynomial method [3]. Although still suffering from methodical shortcomings, our method proves to deliver results close to established results for the orthogonal symmetry class [4]. We extend previous approaches [5] by combining the KPM with a finite-size scaling analysis. We also discuss the relevance of our findings for systems like phosphor-doped silicon (Si:P), which are known to exhibit a quantum phase transition from metal to insulator driven by the interplay of both interaction and disorder, accompanied by the presence of a finite concentration of magnetic moments [6].

  8. Anderson metal-insulator transitions with classical magnetic impurities

    NASA Astrophysics Data System (ADS)

    Jung, Daniel; Kettemann, Stefan; Slevin, Keith

    2016-04-01

    We study numerically the effects of classical magnetic impurities on the Anderson metal-insulator transition. We find that a small concentration of Heisenberg impurities enhances the critical disorder amplitude Wc with increasing exchange coupling strength J . The resulting scaling with J is analyzed which supports an anomalous scaling prediction by Wegner due to the combined breaking of time-reversal and spin-rotational symmetry. Moreover, we find that the presence of magnetic impurities lowers the critical correlation length exponent ν and enhances the multifractality parameter α0. The new value of ν improves the agreement with the value measured in experiments on the metal-insulator transition (MIT) in doped semiconductors like phosphor-doped silicon, where a finite density of magnetic moments is known to exist in the vicinity of the MIT. The results are obtained by a finite-size scaling analysis of the geometric mean of the local density of states which is calculated by means of the kernel polynomial method. We establish this combination of numerical techniques as a method to obtain critical properties of disordered systems quantitatively.

  9. Local nature of impurity induced spin-orbit torques

    NASA Astrophysics Data System (ADS)

    Nikolaev, Sergey; Kalitsov, Alan; Chshiev, Mairbec; Mryasov, Oleg

    Spin-orbit torques are of a great interest due to their potential applications for spin electronics. Generally, it originates from strong spin orbit coupling of heavy 4d/5d elements and its mechanism is usually attributed either to the Spin Hall effect or Rashba spin-orbit coupling. We have developed a quantum-mechanical approach based on the non-equilibrium Green's function formalism and tight binding Hamiltonian model to study spin-orbit torques and extended our theory for the case of extrinsic spin-orbit coupling induced by impurities. For the sake of simplicity, we consider a magnetic material on a two dimensional lattice with a single non-magnetic impurity. However, our model can be easily extended for three dimensional layered heterostructures. Based on our calculations, we present the detailed analysis of the origin of local spin-orbit torques and persistent charge currents around the impurity, that give rise to spin-orbit torques even in equilibrium and explain the existence of anisotropy.

  10. Startup impurity diagnostics in Wendelstein 7-X stellarator in the first operational phase

    NASA Astrophysics Data System (ADS)

    Thomsen, H.; Langenberg, A.; Zhang, D.; Bertschinger, G.; Biedermann, C.; Biel, W.; Burhenn, R.; Buttenschön, B.; Grosser, K.; König, R.; Kubkowska, M.; Marchuk, O.; Pablant, N.; Ryc, L.; Pedersen, T. S.; the W7-X Team

    2015-10-01

    An essential element for stationary stellarator operation is the understanding of the impurity transport behavior. Neoclassical theory predicts an impurity transport towards the plasma core for the standard ion root regime in stellarators [1,2]. The performance of a quasi-stationary device like Wendelstein 7-X stellarator (W7-X, presently in the commissioning phase in Greifswald, Germany) could be limited in case of strong impurity accumulation. Therefore, a set of plasma diagnostics is foreseen to obtain key experimental quantities for the neoclassical transport modeling as ion temperature profile, density gradients and impurity concentration [1]. The core impurity content is monitored by the High Efficiency eXtreme ultraviolet Overview Spectrometer system (HEXOS) [2], covering the wavelength range 2.5-160 nm (intermediate ionization states of all relevant heavy intrinsic impurity species) with high spectral resolution and a time resolution of 1 ms, adequate for transport analysis. Impurity radiation at shorter wave lengths (4 nm-0.06 nm) will be monitored with the SX pulse height analysis system (PHA) [3]. The ion temperature profile can be deduced from inversion of data from the High Resolution X-ray Imaging Spectrometer (HR-XIS), which measures the concentration and temperature of argon tracer gas in helium-like ionization stages [6,7,8]. A second X-ray Imaging Crystal Spectrometer (XICS), which will additionally provide the poloidal ion rotation velocity, is under preparation [8,9]. The total radiation will be measured by two bolometer cameras [10,11]. The status of the impurity diagnostics for the first operational phase in W7-X is summarized in this paper and an outlook for the next experimental campaign is given.

  11. Modeling of Carbon Impurity Anomalous Transport

    NASA Astrophysics Data System (ADS)

    Stamm, Roland; Voitsekhovitch, Irina; Benkadda, Sadri; Beyer, Peter; Koubiti, Mohamed; Marandet, Yannick; Godbert-Mouret, Laurence; Bateman, Glenn; Kritz, Arnold; Pankin, Andre

    2001-10-01

    An improvement of plasma confinement by impurity seeding has been observed on different Tokamak. The understanding of the physics of the impurity transport is an important step towards the control of the plasma confinement in such regimes. Different physical mechanisms of the anomalous transport of carbon impurity and their impact on the evolution of the scenario of a tokamak discharge are analyzed in this work. This is done by using a self-consistent modeling of thermal electron and ion energy, and main ion and carbon impurity content with the multi-mode model taking into account the contributions from different types of plasma instabilities [1]. This study has been performed for the medium size tokamak with a central heating of the electron and ion species, and with both central (NBI) and wall particle source. The L-mode scenario and the scenario with an improved particle and energy confinement due to the reversed q-profile has been analyzed and the influence of the carbon impurity on the plasma evolution has been investigated by varying the starting time and the magnitude of the carbon influx. The effect of the main ion dilution on the growth rate as well as the effect of radiative cooling at the plasma edge on the power balance are analyzed under different conditions. 1. Bateman G., et al., Phys. Plasmas, 5 (1998) 1793

  12. Impurities in the Lithium Tokamak Experiment

    NASA Astrophysics Data System (ADS)

    Boyle, D. P.; Bell, R. E.; Kaita, R.; Majeski, R.; Biewer, T. M.; Gray, T. K.; Tritz, K.; Widmann, K.

    2014-10-01

    The Lithium Tokamak Experiment (LTX) is designed to study the low-recycling regime through the use of close-fitting, lithium-coated, heatable shell quadrants surrounding the plasma volume. Lithium coatings can getter and bury impurities, but they can also become covered by impurity compounds. Liquefied coatings can both dissolve impurity compounds and bring them to the surface, while sputtering and evaporation rates increase strongly with temperature. Here, we use spectroscopic measurements to assess the effects of varying wall conditions on plasma impurities, mainly Li, C, and O. A passive Doppler spectroscopy system measures toroidal and poloidal impurity profiles using fixed-wavelength and variable-wavelength visible spectrometers. In addition, survey and high-resolution extreme ultraviolet spectrometers detect emission from higher charge states. Preliminary results show that fresh Li coatings generally reduced C and O emission. C emission decreased sharply following the first solid Li coatings. Inverted toroidal profiles in a discharge with solid Li coatings show peaked Li III emissivity and temperature profiles. Recently, experiments with fresh liquid coatings led to especially strong O reduction. Results from these and additional experiments will be presented. Supported by US DOE Contracts DE-AC02-09CH11466 and DE-AC05-00OR22725.

  13. Rydberg Impurity Probes in Ultracold Gases

    NASA Astrophysics Data System (ADS)

    Mitchison, Mark; Johnson, Tomi; Plenio, Martin; Jaksch, Dieter

    2015-03-01

    Impurities immersed in ultracold gases can act as highly sensitive, tunable and potentially non-destructive probes of their environment. In this setting, we propose the use of an atomic impurity in a Rydberg state to measure density fluctuations via Ramsey interferometry. The rapid collisional dynamics of the light Rydberg electron interacting with the heavy gas particles, combined with the capability to quickly change the state of the impurity with optical pulses, make such a probe ideal for measuring local properties of ultracold gases. Our proposed device promises angle-resolved density measurements with sub-micron spatial resolution, and with no need to integrate over the line of sight. We outline how Rydberg impurity probes could be applied to study various interesting quantum states of current experimental relevance. We also discuss the possibility of using multiple Rydberg atoms to extract the spatial pair distribution function g (2) (r). Our work is placed in the context of other recently proposed impurity-based probes.

  14. Gettering of metal impurities in silicon

    SciTech Connect

    Schroeter, W.; Spiecker, E.; Apel, M.

    1995-08-01

    Gettering means the removal of metallic impurities from the device-active area of the wafer by transport to a predesigned region-called gettering layer (GL). We introduce an interface at z = d{sub GL}, at which the effect of the gettering mechanism on the metal impurity distribution in the wafer is quantified, e.g. by specifying currents or by interfacial reactions of metal impurities, self interstitials etc. between GL and wafer. In response metal impurities will diffuse out of the wafer into the gettering layer. Following such a concept, in general three species of the metal impurity (M) are involved in gettering: M{sub p} {l_arrow} M{sub i} {l_arrow} M{sub GL}. M{sub p} denotes immobile species in the wafer, which are precipitated into suicides or segregated at extended defects or whose diffusivity is too small to contribute noticeably to transport during the gettering procedure - like many substitutional metal species.

  15. Interaction-induced localization of mobile impurities in ultracold systems

    PubMed Central

    Li, Jian; An, Jin; Ting, C. S.

    2013-01-01

    The impurities, introduced intentionally or accidentally into certain materials, can significantly modify their characteristics or reveal their intrinsic physical properties, and thus play an important role in solid-state physics. Different from those static impurities in a solid, the impurities realized in cold atomic systems are naturally mobile. Here we propose an effective theory for treating some unique behaviors exhibited by ultracold mobile impurities. Our theory reveals the interaction-induced transition between the extended and localized impurity states, and also explains the essential features obtained from several previous models in a unified way. Based on our theory, we predict many intriguing phenomena in ultracold systems associated with the extended and localized impurities, including the formation of the impurity-molecules and impurity-lattices. We hope this investigation can open up a new avenue for the future studies on ultracold mobile impurities. PMID:24192986

  16. Interaction-induced localization of mobile impurities in ultracold systems

    NASA Astrophysics Data System (ADS)

    Li, Jian; An, Jin; Ting, C. S.

    2013-11-01

    The impurities, introduced intentionally or accidentally into certain materials, can significantly modify their characteristics or reveal their intrinsic physical properties, and thus play an important role in solid-state physics. Different from those static impurities in a solid, the impurities realized in cold atomic systems are naturally mobile. Here we propose an effective theory for treating some unique behaviors exhibited by ultracold mobile impurities. Our theory reveals the interaction-induced transition between the extended and localized impurity states, and also explains the essential features obtained from several previous models in a unified way. Based on our theory, we predict many intriguing phenomena in ultracold systems associated with the extended and localized impurities, including the formation of the impurity-molecules and impurity-lattices. We hope this investigation can open up a new avenue for the future studies on ultracold mobile impurities.

  17. Identification, Characterization, Synthesis and Quantification of Related Impurities of Liguzinediol.

    PubMed

    Cheng, Dong; Zhou, Ying; Li, Wei; Shan, Chen-Xiao; Chai, Chuan; Cui, Xiao-Bing; Kang, Bi; Wang, Tian-Lin; Wen, Hong-Mei

    2015-09-01

    An HPLC method was employed to create an impurity profile for liguzinediol as an active pharmaceutical ingredient (API), which resulted in the identification of two related impurities. Therefore, in order to improve the quality control of the liguzinediol-API, we identified and then developed a method for quantifying the two impurities (impurity-1 and impurity-2) by LC-TOF-MS-MS and then chemically synthesized them for further studies. Based on spectral data from IR, MS, (1)H and (13)C NMR, the structures of impurity-1 and impurity-2 were characterized as 2-hydroxymethyl-3,6-dimethylpyrazine and 2-hydroxymethyl-3,5,6-trimethylpyrazine, respectively. We further validated the method according to the International Conference on Harmonization guidelines to demonstrate the sensitivity, precision, linearity, accuracy and stability of the method described. In addition, the potential mechanisms underlying formation of impurity-1 and impurity-2 in the liguzinediol-API are discussed in detail. PMID:25680683

  18. On charged impurity structures in liquid helium

    NASA Astrophysics Data System (ADS)

    Pelmenev, A. A.; Krushinskaya, I. N.; Bykhalo, I. B.; Boltnev, R. E.

    2016-03-01

    The thermoluminescence spectra of impurity-helium condensates (IHC) submerged in superfluid helium have been observed for the first time. Thermoluminescence of impurity-helium condensates submerged in superfluid helium is explained by neutralization reactions occurring in impurity nanoclusters. Optical spectra of excited products of neutralization reactions between nitrogen cations and thermoactivated electrons were rather different from the spectra observed at higher temperatures, when the luminescence due to nitrogen atom recombination dominates. New results on current detection during the IHC destruction are presented. Two different mechanisms of nanocluster charging are proposed to describe the phenomena observed during preparation and warm-up of IHC samples in bulk superfluid helium, and destruction of IHC samples out of liquid helium.

  19. Impurity and particle control for INTOR

    SciTech Connect

    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.

  20. Characteristics of impurity-induced pseudogap

    NASA Astrophysics Data System (ADS)

    Numata, Yoshinori; Uto, Tatsuro; Matuda, Azusa

    2016-05-01

    We have performed STM/STS measurements on a single crystal of Bi2.1Sr1.9Ca (Cu1-xCox) 2O8+δ (Co-Bi2212), to reveal impurity effects on the pseudogap in cuprate high-Tc superconductors. We report a drastic change in the temperature dependence of a pseudogap and in the density of states (DOS) modulation with a 4a period, in a certain doping range. In the Co 4% substituted samples, the pseudogap gradually closed like a gap of a BCS superconductor for slightly overdoped and overdoped regime, while their low temperature values were enhanced due to impurity. In addition, a disappearance of a 4a periodic modulation and a development of new modulation were observed in the DOS spatial distribution. These results indicate an intimate relation between the DOS modulation and the pseudogap, and qualitative difference in the impurity enhanced pseudogap and conventional one.

  1. Progress in nonmagnetic impurity doping studies on Fe-based superconductors

    NASA Astrophysics Data System (ADS)

    Li, Jun; Guo, Yan-Feng; Yang, Zhao-Rong; Yamaura, Kazunari; Takayama-Muromachi, Eiji; Wang, Hua-Bing; Wu, Pei-Heng

    2016-05-01

    We review the progress of nonmagnetic impurity doping studies on Fe-based superconductors. On the theoretical side, two highly promising candidates for the pairing symmetry order parameter, i.e. the multi-gap s ++ and s ± wave models, have been proposed but continuously debated. The debate arises because of the complex gap structure and exceptional magnetic and metallic behaviors of Fe-based superconductors, which may vary the influence of nonmagnetic defects in the chemical potential, impurity disorder, inter- and intra-band scattering strength, and electron localization. This creates difficulties in directly obtaining the most important information for understanding the symmetry order parameter. Experimentally, nonmagnetic impurity substitution studies have been widely carried out, which have provided very useful insights. We review herein the various nonmagnetic impurity doping experiments, including the controlled defects within the superconducting Fe2 X 2 planes through sample quality improvement, single impurity effects on the electronic state and local moment, the magnetic response of the Fe2 X 2 planes both on the macroscopic scale as the antiferromagnetic state and the local scale of moment, as well as the significant effect of modifying the transport properties. The experiments enable us to qualitatively analyze the nonmagnetic impurity effects on the superconducting state for many Fe-based superconductors. We also propose herein some strategies for nonmagnetic impurity doping study. As an important model for explaining the nonmagnetic impurity doping effects, the pair-breaking model is compared with various theoretical approaches via analysis of the pair-breaking rates of various Fe-superconductors.

  2. Host cell protein impurities in chromatographic polishing steps for monoclonal antibody purification.

    PubMed

    Levy, Nicholas E; Valente, Kristin N; Lee, Kelvin H; Lenhoff, Abraham M

    2016-06-01

    Downstream purification of monoclonal antibodies (mAbs) is normally performed using a platform process that is empirically tuned to optimize impurity removal for each new product. A more fundamental understanding of impurities and the product itself would provide insights into the rational design of efficient downstream processes. This work examines the chromatographic properties of Chinese hamster ovary host cell protein (HCP) impurities in non-affinity chromatographic resins commonly used in polishing steps for monoclonal antibody purification: ion-exchange, hydrophobic interaction, and multimodal. Using proteomic analysis, the specific HCP impurities that elute close to mAb products are identified for these resins at typical downstream processing conditions. Additionally, the interactions of HCP impurities with mAb products are profiled to determine the total extent of product association and the specific HCP species that form associative complexes under conditions encountered in polishing columns. Product association and co-elution were both identified as viable mechanisms of HCP retention for the non-affinity resins tested here. A relatively large sub-population of HCP impurities was found to co-elute or associate with mAbs in each polishing column, but only a small population of HCPs-including lipoprotein lipase, chrondroitin sulfate proteoglycan 4, nidogen-1, and SPARC-were identified as difficult to remove across an entire downstream mAb process. Biotechnol. Bioeng. 2016;113: 1260-1272. © 2015 Wiley Periodicals, Inc. PMID:26550778

  3. The physics of Kondo impurities in graphene

    NASA Astrophysics Data System (ADS)

    Fritz, Lars; Vojta, Matthias

    2013-03-01

    This article summarizes our understanding of the Kondo effect in graphene, primarily from a theoretical perspective. We shall describe different ways to create magnetic moments in graphene, either by adatom deposition or via defects. For dilute moments, the theoretical description is in terms of effective Anderson or Kondo impurity models coupled to graphene's Dirac electrons. We shall discuss in detail the physics of these models, including their quantum phase transitions and the effect of carrier doping, and confront this with existing experimental data. Finally, we will point out connections to other quantum impurity problems, e.g., in unconventional superconductors, topological insulators, and quantum spin liquids.

  4. The physics of Kondo impurities in graphene.

    PubMed

    Fritz, Lars; Vojta, Matthias

    2013-03-01

    This article summarizes our understanding of the Kondo effect in graphene, primarily from a theoretical perspective. We shall describe different ways to create magnetic moments in graphene, either by adatom deposition or via defects. For dilute moments, the theoretical description is in terms of effective Anderson or Kondo impurity models coupled to graphene's Dirac electrons. We shall discuss in detail the physics of these models, including their quantum phase transitions and the effect of carrier doping, and confront this with existing experimental data. Finally, we will point out connections to other quantum impurity problems, e.g., in unconventional superconductors, topological insulators, and quantum spin liquids. PMID:23411583

  5. Mapping itinerant electrons around Kondo impurities.

    PubMed

    Prüser, H; Wenderoth, M; Weismann, A; Ulbrich, R G

    2012-04-20

    We investigate single Fe and Co atoms buried below a Cu(100) surface using low temperature scanning tunneling spectroscopy. By mapping the local density of states of the itinerant electrons at the surface, the Kondo resonance near the Fermi energy is analyzed. Probing bulk impurities in this well-defined scattering geometry allows separating the physics of the Kondo system and the measuring process. The line shape of the Kondo signature shows an oscillatory behavior as a function of depth of the impurity as well as a function of lateral distance. The oscillation period along the different directions reveals that the spectral function of the itinerant electrons is anisotropic. PMID:22680744

  6. Two-impurity helical Majorana problem

    NASA Astrophysics Data System (ADS)

    Eriksson, Erik; Zazunov, Alex; Sodano, Pasquale; Egger, Reinhold

    2015-02-01

    We predict experimentally accessible signatures for helical Majorana fermions in a topological superconductor by coupling to two quantum dots in the local moment regime (corresponding to spin-1 /2 impurities). Taking into account Ruderman-Kittel-Kasuya-Yosida interactions mediated by bulk and edge modes, where the latter cause a long-range antiferromagnetic Ising coupling, we formulate and solve the low-energy theory for this two-impurity helical Majorana problem. In particular, we show that the long-time spin dynamics after a magnetic field quench displays weakly damped oscillations with universal quality factor.

  7. Influence of impurities on the crystallization of dextrose monohydrate

    NASA Astrophysics Data System (ADS)

    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.

  8. The Effect of Impurities on Firn Layering

    NASA Astrophysics Data System (ADS)

    Keegan, K. M.; Baker, I.; Albert, M. R.

    2013-12-01

    Recently, there has been increased interest in incorporating firn layering into firn densification models, and a correlation between impurities and density differences in firn layering has been described. Measuring the stratigraphy from firn cores is a tedious process, but a chemical proxy for firn layering would be an easy way to incorporate layering into the existing firn models. To explore the correlation of chemical impurities in firn, we collected Raman spectra from samples of a NEEM 2009 firn core using a confocal scanning optical microscope with a Raman spectrometer. We found sulfuric acid (H2SO4), calcium carbonate (CaCO3), gypsum (CaSO4*2H2O), hydroxyl herderite (CaBePO4(OH)), and sodium chloride (NaCl) in the firn with a greater concentration of these impurities at the grain boundaries and triple junctions. We will discuss the effects of these impurities on the firn densification processes, as well as the potential for a proxy of layering in firn densification models.

  9. Collisionality dependence of impurity transport in Alcator C-Mod H-modes

    NASA Astrophysics Data System (ADS)

    Chilenski, M. A.; Greenwald, M.; Howard, N. T.; Reinke, M. L.; Rice, J.; White, A. E.; Marzouk, Y.

    2014-10-01

    Understanding and actuating impurity transport is of particular interest for future machines because of the concern that core accumulation of heavy impurities will lead to radiative collapse and higher disruptivity. This problem is expected to be especially pronounced at low collisionality, where a strong peaking of the electron density profile has previously been observed (Greenwald et al., Nucl. Fusion 47, L26 (2007)). To investigate this issue several experiments have been performed in Alcator C-Mod to measure the behavior of mid-Z (Ar, Ca) and high-Z (Mo, W) impurities in H-mode plasmas of varying collisionality (2 <νeff < 40). These plasmas are of particular interest to this problem because they are entirely RF heated and lack core particle sources. Impurities are injected using laser blow-off or gas injection and the evolution of the impurity density profile is constrained with an X-ray imaging crystal spectrometer. These diagnostics combined with analysis using STRAHL allows detailed study of the transport. Furthermore, analysis of the background ne, Te profiles is conducted using advanced techniques including Gaussian process regression. An outline of this analysis scheme will be presented and recent results obtained from its application will be shown. Supported by USDOE Award DE-FC02-99ER54512.

  10. Distribution Coefficients of Impurities in Metals

    NASA Astrophysics Data System (ADS)

    Pearce, J. V.

    2014-04-01

    Impurities dissolved in very pure metals at the level of parts per million often cause an elevation or depression of the freezing temperature of the order of millikelvins. This represents a significant contribution to the uncertainty of standard platinum resistance thermometer calibrations. An important parameter for characterizing the behavior of impurities is the distribution coefficient , which is the ratio of the solid solubility to liquid solubility. A knowledge of for a given binary system is essential for contemporary methods of evaluating or correcting for the effect of impurities, and it is therefore of universal interest to have the most complete set of values possible. A survey of equilibrium values of (in the low concentration limit) reported in the literature for the International Temperature Scale of 1990 fixed points of Hg, Ga, In, Sn, Zn, Al, Au, Ag, and Cu is presented. In addition, thermodynamic calculations of using MTDATA are presented for 170 binary systems. In total, the combined values of from all available sources for 430 binary systems are presented. In addition, by considering all available values of for impurities in 25 different metal solvents (1300 binary systems) enough data are available to characterize patterns in the value of for a given impurity as a function of its position in the periodic table. This enables prediction of for a significant number of binary systems for which data and calculations are unavailable. By combining data from many sources, values of for solutes (atomic number from 1 to 94) in ITS-90 fixed points from Hg to Cu are suggested, together with some tentative predicted values where literature data and calculations are unavailable.

  11. Process and system for removing impurities from a gas

    SciTech Connect

    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.

  12. Impurity transport in trapped electron mode driven turbulence

    SciTech Connect

    Mollen, A.; Fueloep, T.; Moradi, S.; Pusztai, I.

    2013-03-15

    Trapped electron mode turbulence is studied by gyrokinetic simulations with the GYRO code and an analytical model including the effect of a poloidally varying electrostatic potential. Its impact on radial transport of high-Z trace impurities close to the core is thoroughly investigated, and the dependence of the zero-flux impurity density gradient (peaking factor) on local plasma parameters is presented. Parameters such as ion-to-electron temperature ratio, electron temperature gradient, and main species density gradient mainly affect the impurity peaking through their impact on mode characteristics. The poloidal asymmetry, the safety factor, and magnetic shear have the strongest effect on impurity peaking, and it is shown that under certain scenarios where trapped electron modes are dominant, core accumulation of high-Z impurities can be avoided. We demonstrate that accounting for the momentum conservation property of the impurity-impurity collision operator can be important for an accurate evaluation of the impurity peaking factor.

  13. The Question of Impurities in Macromolecule Crystal Quality Improvement in Microgravity

    NASA Technical Reports Server (NTRS)

    Judge, Russell A.; Snell, Edward H.; Pusey, Marc L.; Sportiello, Michael G.; Todd, Paul; Bellamy, Henry; Borgstahl, Gloria E.; Pokros, Matthew; Cassanto, John M.

    2000-01-01

    While macromolecule impurities may affect crystal size and morphology the over-riding question is how do macromolecule impurities effect crystal X-ray quality and diffraction resolution. In the case of chicken egg white lysozyme previous researchers have reported that crystals grown in the presence of ovalbumin, ovotransferrin, and turkey egg white lysozyme show no difference in diffraction resolution compared to those grown in pure solutions. One impurity however, a naturally occurring lysozyme dimer, does negatively impact the X-ray crystal properties. For this impurity it has been reported that crystal quality improvement in microgravity may be due to improved impurity partitioning during crystallization. In this study we have examined the incorporation of the dimer into lysozyme crystals, both on the ground and in microgravity experiments, and have performed detailed X-ray analysis of the crystals using a new technique for finely probing the mosaicity of the crystal at the Stanford Synchrotron Radiation Laboratory. Dimer partitioning was not significantly different in microgravity compared to the ground based experiments, although it is significantly better than that previously reported in microgravity. Mosaicity analysis of pure crystals, 1422 indexed reflections (microgravity) and 752 indexed reflections (ground), gave average results of 0.0066 and 0.0092 degrees (FWHM) respectively. The microgravity crystals also provided an increased signal to noise. Dimer incorporation increased the average mosaicity in microgravity but not on the ground. However, dimer incorporation did greatly reduce the resolution limit in both ground and microgravity grown crystals. The data is being treated anisotropically to explore these effects. These results indicate that impurity effects in microgravity are complex and that the conditions or techniques employed may greatly affect the role of impurities.

  14. The Potts model on a Bethe lattice with nonmagnetic impurities

    SciTech Connect

    Semkin, S. V. Smagin, V. P.

    2015-10-15

    We have obtained a solution for the Potts model on a Bethe lattice with mobile nonmagnetic impurities. A method is proposed for constructing a “pseudochaotic” impurity distribution by a vanishing correlation in the arrangement of impurity atoms for the nearest sites. For a pseudochaotic impurity distribution, we obtained the phase-transition temperature, magnetization, and spontaneous magnetization jumps at the phase-transition temperature.

  15. Protein Crystal Growth Dynamics and Impurity Incorporation

    NASA Technical Reports Server (NTRS)

    Chernov, Alex A.; Thomas, Bill

    2000-01-01

    The general concepts and theories of crystal growth are proven to work for biomolecular crystallization. This allowed us to extract basic parameters controlling growth kinetics - free surface energy, alpha, and kinetic coefficient, beta, for steps. Surface energy per molecular site in thermal units, alpha(omega)(sup 2/3)/kT approx. = 1, is close to the one for inorganic crystals in solution (omega is the specific molecular volume, T is the temperature). Entropic restrictions on incorporation of biomolecules into the lattice reduce the incorporation rate, beta, by a factor of 10(exp 2) - 10(exp 3) relative to inorganic crystals. A dehydration barrier of approx. 18kcal/mol may explain approx. 10(exp -6) times difference between frequencies of adding a molecule to the lattice and Brownian attempts to do so. The latter was obtained from AFM measurements of step and kink growth rates on orthorhombic lysozyme. Protein and many inorganic crystals typically do not belong to the Kossel type, thus requiring a theory to account for inequivalent molecular positions within its unit cell. Orthorhombic lysozyme will serve as an example of how to develop such a theory. Factors deteriorating crystal quality - stress and strain, mosaicity, molecular disorder - will be reviewed with emphasis on impurities. Dimers in ferritin and lysozyme and acetylated lysozyme, are microheterogeneous i.e. nearly isomorphic impurities that are shown to be preferentially trapped by tetragonal lysozyme and ferritin crystals, respectively. The distribution coefficient, K defined as a ratio of the (impurity/protein) ratios in crystal and in solution is a measure of trapping. For acetylated lysoyzme, K = 2.15 or, 3.42 for differently acetylated forms, is independent of both the impurity and the crystallizing protein concentration. The reason is that impurity flux to the surface is constant while the growth rate rises with supersaturation. About 3 times lower dimer concentration in space grown ferritin and

  16. Practical and highly sensitive elemental analysis for aqueous samples containing metal impurities employing electrodeposition on indium-tin oxide film samples and laser-induced shock wave plasma in low-pressure helium gas.

    PubMed

    Kurniawan, Koo Hendrik; Pardede, Marincan; Hedwig, Rinda; Abdulmadjid, Syahrun Nur; Lahna, Kurnia; Idris, Nasrullah; Jobiliong, Eric; Suyanto, Hery; Suliyanti, Maria Margaretha; Tjia, May On; Lie, Tjung Jie; Lie, Zener Sukra; Kurniawan, Davy Putra; Kagawa, Kiichiro

    2015-09-01

    We have conducted an experimental study exploring the possible application of laser-induced breakdown spectroscopy (LIBS) for practical and highly sensitive detection of metal impurities in water. The spectrochemical measurements were carried out by means of a 355 nm Nd-YAG laser within N2 and He gas at atmospheric pressures as high as 2 kPa. The aqueous samples were prepared as thin films deposited on indium-tin oxide (ITO) glass by an electrolysis process. The resulting emission spectra suggest that concentrations at parts per billion levels may be achieved for a variety of metal impurities, and it is hence potentially feasible for rapid inspection of water quality in the semiconductor and pharmaceutical industries, as well as for cooling water inspection for possible leakage of radioactivity in nuclear power plants. In view of its relative simplicity, this LIBS equipment offers a practical and less costly alternative to the standard use of inductively coupled plasma-mass spectrometry (ICP-MS) for water samples, and its further potential for in situ and mobile applications. PMID:26368882

  17. Pharmaceutical impurities and degradation products: uses and applications of NMR techniques.

    PubMed

    Maggio, Rubén M; Calvo, Natalia L; Vignaduzzo, Silvana E; Kaufman, Teodoro S

    2014-12-01

    Current standards and regulations demand the pharmaceutical industry not only to produce highly pure drug substances, but to achieve a thorough understanding of the impurities accompanying their manufactured drug substances and products. These challenges have become important goals of process chemistry and have steadily stimulated the search of impurities after accelerated or forced degradation procedures. As a result, impurity profiling is one of the most attractive, active and relevant fields of modern pharmaceutical analysis. This activity includes the identification, structural elucidation and quantitative determination of impurities and degradation products in bulk drugs and their pharmaceutical formulations. Nuclear magnetic resonance (NMR) spectroscopy has evolved into an irreplaceable approach for pharmaceutical quality assessment, currently playing a critical role in unequivocal structure identification as well as structural confirmation (qualitative detection), enabling the understanding of the underlying mechanisms of the formation of process and/or degradation impurities. NMR is able to provide qualitative information without the need of standards of the unknown compounds and multiple components can be quantified in a complex sample without previous separation. When coupled to separative techniques, the resulting hyphenated methodologies enhance the analytical power of this spectroscopy to previously unknown levels. As a result, and by enabling the implementation of rational decisions regarding the identity and level of impurities, NMR contributes to the goal of making better and safer medicines. Herein are discussed the applications of NMR spectroscopy and its hyphenated derivate techniques to the study of a wide range pharmaceutical impurities. Details on the advantages and disadvantages of the methodology and well as specific challenges with regards to the different analytical problems are also presented. PMID:24853620

  18. Preliminary effects of real-world factors on the recovery and exploitation of forensic impurity profiles of a nerve-agent simulant from office media.

    PubMed

    Fraga, Carlos G; Sego, Landon H; Hoggard, Jamin C; Acosta, Gabriel A Pérez; Viglino, Emilie A; Wahl, Jon H; Synovec, Robert E

    2012-12-28

    Dimethyl methylphosphonate (DMMP) was used as a chemical threat agent (CTA) simulant for a first look at the effects of real-world factors on the recovery and exploitation of a CTA's impurity profile for source matching. Four stocks of DMMP having different impurity profiles were disseminated as aerosols onto cotton, painted wall board, and nylon coupons according to a thorough experimental design. The DMMP-exposed coupons were then solvent extracted and analyzed for DMMP impurities by comprehensive 2D gas chromatography/mass spectrometry (GC×GC/MS). The similarities between the coupon DMMP impurity profiles and the known (reference) DMMP profiles were measured by dot products of the coupon profiles and known profiles and by score values obtained from principal component analysis. One stock, with a high impurity-profile selectivity value of 0.9 out of 1, had 100% of its respective coupons correctly classified and no false positives from other coupons. Coupons from the other three stocks with low selectivity values (0.0073, 0.012, and 0.018) could not be sufficiently distinguished from one another for reliable matching to their respective stocks. The results from this work support that: (1) extraction solvents, if not appropriately selected, can have some of the same impurities present in a CTA reducing a CTA's useable impurity profile, (2) low selectivity among a CTA's known impurity profiles will likely make definitive source matching impossible in some real-world conditions, (3) no detrimental chemical-matrix interference was encountered during the analysis of actual office media, (4) a short elapsed time between release and sample storage is advantageous for the recovery of the impurity profile because it minimizes volatilization of forensic impurities, and (5) forensic impurity profiles weighted toward higher volatility impurities are more likely to be altered by volatilization following CTA exposure. PMID:23177156

  19. Preliminary Effects of Real-World Factors on the Recovery and Exploitation of Forensic Impurity Profiles of a Nerve-Agent Simulant from Office Media

    SciTech Connect

    Fraga, Carlos G.; Sego, Landon H.; Hoggard, Jamin C.; Perez Acosta, Gabriel A.; Viglino, Emilie A.; Wahl, Jon H.; Synovec, Robert E.

    2012-12-28

    Dimethyl methylphosphonate (DMMP) was used as a chemical threat agent (CTA) simulant for a first look at the effects of real-world factors on the recovery and exploitation of a CTA’s impurity profile for source matching. Four stocks of DMMP having different impurity profiles were disseminated as aerosols onto cotton, painted wall board, and nylon coupons according to a thorough experimental design. The DMMP-exposed coupons were then solvent extracted and analyzed for DMMP impurities by comprehensive 2-D gas chromatography/mass spectrometry (GC×GC/MS). The similarities between the coupon DMMP impurity profiles and the known (reference) DMMP profiles were measured by dot products of the coupon profiles and known profiles and by score values obtained from principal component analysis. One stock, with a high impurity-profile selectivity value of 0.9 out of 1, had 100% of its respective coupons correctly classified and no false positives from other coupons. Coupons from the other three stocks with low selectivity values (0.0073, 0.012, and 0.018) could not be sufficiently distinguished from one another for reliable matching to their respective stocks. The results from this work support that: (1) extraction solvents, if not appropriately selected, can have some of the same impurities present in a CTA reducing a CTA’s useable impurity profile, (2) low selectivity among a CTA’s known impurity profiles will likely make definitive source matching impossible in some real-world conditions, (3) no detrimental chemical-matrix interference was encountered during the analysis of actual office media, (4) a short elapsed time between release and sample storage is advantageous for the recovery of the impurity profile because it minimizes volatilization of forensic impurities, and (5) forensic impurity profiles weighted towards higher volatility impurities are more likely to be altered by volatilization following CTA exposure.

  20. HPTLC Method for Quantitative Determination of Zopiclone and Its Impurity.

    PubMed

    Naguib, Ibrahim A; Abdelrahman, Maha M; El Ghobashy, Mohamed R; Ali, Nesma A

    2015-09-01

    This study was designed to establish, optimize and validate a sensitive, selective and accurate high-performance thin layer chromatographic (HPTLC) method for determination of zopiclone (ZPC) and its main impurity, 2-amino-5-chloropyridine, one of its degradation products, in raw material and pharmaceutical formulation. The proposed method was applied for analysis of ZPC and its impurity over the concentration range of 0.3-1.4 and 0.05-0.8 µg/band with accuracy of mean percentage recovery 99.92% ± 1.521 and 99.28% ± 2.296, respectively. The method is based on the separation of two components followed by densitometric measurement of the separated peaks at 305 nm. The separation was carried out on silica gel HPTLC F254 plates, using chloroform-methanol-glacial acetic acid (9:1:0.1, by volume) as a developing system. The suggested method was validated according to International Conference on Harmonization guidelines and can be applied for routine analysis in quality control laboratories. The results obtained by the proposed method were statistically compared with the reported method revealing high accuracy and good precision. PMID:25740427

  1. Impurities effect on the swelling of neutron irradiated beryllium

    SciTech Connect

    Donne, M.D.; Scaffidi-Argentina, F.

    1995-09-01

    An important factor controlling the swelling behaviour of fast neutron irradiated beryllium is the impurity content which can strongly affect both the surface tension and the creep strength of this material. Being the volume swelling of the old beryllium (early sixties) systematically higher than that of the more modem one (end of the seventies), a sensitivity analysis with the aid of the computer code ANFIBE (ANalysis of Fusion Irradiated BEryllium) to investigate the effect of these material properties on the swelling behaviour of neutron irradiated beryllium has been performed. Two sets of experimental data have been selected: the first one named Western refers to quite recently produced Western beryllium, whilst the second one, named Russian refers to relatively old (early sixties) Russian beryllium containing a higher impurity rate than the Western one. The results obtained with the ANFIBE Code were assessed by comparison with experimental data and the used material properties were compared with the data available in the literature. Good agreement between calculated and measured values has been found.

  2. Power Radiated from ITER and CIT by Impurities

    DOE R&D Accomplishments Database

    Cummings, J.; Cohen, S. A.; Hulse, R.; Post, D. E.; Redi, M. H.; Perkins, J.

    1990-07-01

    The MIST code has been used to model impurity radiation from the edge and core plasmas in ITER and CIT. A broad range of parameters have been varied, including Z{sub eff}, impurity species, impurity transport coefficients, and plasma temperature and density profiles, especially at the edge. For a set of these parameters representative of the baseline ITER ignition scenario, it is seen that impurity radiation, which is produced in roughly equal amounts by the edge and core regions, can make a major improvement in divertor operation without compromising core energy confinement. Scalings of impurity radiation with atomic number and machine size are also discussed.

  3. Impurities in Bose-Einstein Condensates: From Polaron to Soliton.

    PubMed

    Shadkhoo, Shahriar; Bruinsma, Robijn

    2015-09-25

    We propose that impurities in a Bose-Einstein condensate which is coupled to a transversely laser-pumped multimode cavity form an experimentally accessible and analytically tractable model system for the study of impurities solvated in correlated liquids and the breakdown of linear-response theory [corrected]. As the strength of the coupling constant between the impurity and the Bose-Einstein condensate is increased, which is possible through Feshbach resonance methods, the impurity passes from a large to a small polaron state, and then to an impurity-soliton state. This last transition marks the breakdown of linear-response theory. PMID:26451565

  4. Interaction of two substitutional impurity atoms in an hcp crystal

    NASA Astrophysics Data System (ADS)

    Belan, V. I.; Landau, A. I.

    2010-04-01

    Molecular dynamics computer simulation with a Lennard-Jones potential is used to investigate the interaction of two identical substitutional impurity atoms in an hcp crystal lattice. Different atomic radii of the impurities atoms, interaction energy of the atoms and the lattice atoms, and initial distances between the impurity atoms at zero temperature and pressure. It is found that in a number of cases for small distances between the impurity atoms not exceeding five interatomic distances these atoms attract one another contrary to the well-known laws of the continuum theory of elasticity. Good agreement between the computational results and the theory of elasticity obtains for short distances between impurity atoms.

  5. Bound States in Boson Impurity Models

    NASA Astrophysics Data System (ADS)

    Shi, Tao; Wu, Ying-Hai; González-Tudela, A.; Cirac, J. I.

    2016-04-01

    The formation of bound states involving multiple particles underlies many interesting quantum physical phenomena, such as Efimov physics or superconductivity. In this work, we show the existence of an infinite number of such states for some boson impurity models. They describe free bosons coupled to an impurity and include some of the most representative models in quantum optics. We also propose a family of wave functions to describe the bound states and verify that it accurately characterizes all parameter regimes by comparing its predictions with exact numerical calculations for a one-dimensional tight-binding Hamiltonian. For that model, we also analyze the nature of the bound states by studying the scaling relations of physical quantities, such as the ground-state energy and localization length, and find a nonanalytical behavior as a function of the coupling strength. Finally, we discuss how to test our theoretical predictions in experimental platforms, such as photonic crystal structures and cold atoms in optical lattices.

  6. Extrinsic germanium Blocked Impurity Bank (BIB) detectors

    NASA Technical Reports Server (NTRS)

    Krabach, Timothy N.; Huffman, James E.; Watson, Dan M.

    1989-01-01

    Ge:Ga blocked-impurity-band (BIB) detectors with long wavelength thresholds greater than 190 microns and peak quantum efficiencies of 4 percent, at an operating temperature of 1.8 K, have been fabricated. These proof of concept devices consist of a high purity germanium blocking layer epitaxially grown on a Ga-doped Ge substrate. This demonstration of BIB behavior in germanium enables the development of far infrared detector arrays similar to the current silicon-based devices. Present efforts are focussed on improving the chemical vapor deposition process used to create the blocking layer and on the lithographic processing required to produce monolithic detector arrays in germanium. Approaches to test the impurity levels in both the blocking and active layers are considered.

  7. Physicochemical characterization of ezetimibe and its impurities

    NASA Astrophysics Data System (ADS)

    Filip, Katarzyna; Bańkowski, Krzysztof; Sidoryk, Katarzyna; Zagrodzka, Joanna; Łaszcz, Marta; Trzcińska, Kinga; Szyprowska, Anna; Cmoch, Piotr; Maruszak, Wioleta

    2011-04-01

    The physicochemical characterization of major degradation and process-related impurities associated with the synthesis of ezetimibe was performed. The possibility of forming the undesirable ( R, R, S) stereoisomer of ezetimibe has been mentioned in literature (Vinod KK, Suhail A, Bhupendra T, Nitin G US 2010/0010212 A1, Ind-Swift Laboratories Limited WO 2008/096372), but no study of its structure determination has been published yet. This paper discusses the structure elucidation of the ( R, R, S) stereoisomer as well as ezetimibe degradation product on the bases of NMR, IR and MS data. Other potential impurities of ezetimibe are also described. A selective and stability-indicating high-performance liquid chromatography method with dual UV detection was developed for the determination of chemical and stereochemical purity of ezetimibe. The characterization of particle size and shape for ezetimibe and its stereoisomer is also described.

  8. Metal impurities in food and drugs.

    PubMed

    Abernethy, Darrell R; Destefano, Anthony J; Cecil, Todd L; Zaidi, Kahkashan; Williams, Roger L

    2010-05-01

    The major metals of potential health concern found in food, drugs (medicines), and dietary supplements are lead, cadmium, mercury, and arsenic. Other metals, such as chromium, copper, manganese, molybdenum, vanadium, nickel, osmium, rhodium, ruthenium, iridium, palladium, and platinum, may be used or introduced during manufacturing and may be controlled in the final article as impurities. Screening for metals in medicines and dietary supplements rarely indicates the presence of toxic metal impurities at levels of concern. The setting of heavy metal limits is appropriate for medicines and is appropriate for supplements when heavy metals are likely or certain to contaminate a given product. Setting reasonable health-based limits for some of these metals is challenging because of their ubiquity in the environment, limitations of current analytical procedures, and other factors. Taken together, compendial tests for metals in food and drugs present an array of issues that challenge compendial scientists. PMID:20217462

  9. Tin impurity centers in glassy germanium chalcogenides

    SciTech Connect

    Bordovsky, G. A.; Gladkikh, P. V.; Kozhokar, M. Yu.; Marchenko, A. V.; Seregin, P. P.; Terukov, E. I.

    2011-10-15

    Tin atoms produced by radioactive decay of {sup 119mm}Sn and {sup 119}Sn impurity atoms in the structure of Ge{sub x}S{sub 1-x} and Ge{sub x}Se{sub 1-x} glasses are stabilized in the form of Sn{sup 2+} and Sn{sup 4+} ions and correspond to ionized states of the amphoteric two-electron center with negative correlation energy (Sn{sup 2+} is an ionized acceptor, and Sn{sup 4+} is an ionized donor), whereas the neutral state of the Sn{sup 3+} center appears to be unstable. {sup 119}Sn atoms produced by radioactive decay of {sup 119m}Te impurity atoms in the structure of Ge{sub x}S{sub 1-x} and Ge{sub x}Se{sub 1-x} glasses are stabilized at both chalcogen sites (they are electrically inactive) and germanium sites.

  10. Heat of segregation of single substitutional impurities

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Good, Brian; Ferrante, John

    1993-01-01

    The method of Bozzolo, Ferrante and Smith (BFS) is applied for the calculation of the heat of segregation of single substitutional impurities in fcc metals. A simple equation for predicting the heat of segregation is derived for the rigid case (no atomic relaxations). The results of including atomic relaxation using a Monte Carlo method are also presented and the results compared with a number of experimental and theoretical results.

  11. Impurities: Curse and blessing for crystal growers

    NASA Astrophysics Data System (ADS)

    Fox, Donald K.; Mazelsky, R.

    1990-11-01

    The indespensability of high-quality source materials research and development has been established for many years. However, because contributors to this field are diverse and communication of research results is often fragmented, transfer of the new knowledge is very slow. This paper describes how increasing source purity has improved the quality of several crystals, and how the addition of controlled impurities has decreased the defect density in these crystals. Experimental evidence is presented in this paper.

  12. Inhomogeneous CDMFT and nonmagnetic impurities in graphene

    NASA Astrophysics Data System (ADS)

    Charlebois, M.; Sénéchal, D.; Gagnon, A.-M.; Tremblay, A.-M. S.

    In cluster dynamical mean-field theory (CDMFT), we usually apply the self-consistency condition on an infinite super-lattice of identical clusters. However, in some problems a large unit cell is required, for instance in the presence of a periodically repeated impurity. Since the impurity solver (exact diagonalization) can only treat small clusters, we break the unit cell into multiple small clusters that can be solved individually. This new technique is called inhomogeneous CDMFT (1) and is analogous to inhomogeneous DMFT (2). In this presentation, we will explain both the CDMFT and inhomogeneous CDMFT self-consistency loops within a unified, simple picture. We then apply this technique to a nonmagnetic impurity in graphene and study the emerging magnetism. Our results take into account dynamical correlations; nevertheless they qualitatively agree with previous mean-field and density functional theory studies. (1) Charlebois, M. et al., Phys. Rev. B 91, 035132 (2015). (2) Snoek, M. et al., New J. Phys. 10, 093008 (2008). Supported by NSERC, CIFAR and the Tier I Canada Research Chair Program.

  13. Phase growth in bistable systems with impurities.

    PubMed

    Echeverria, C; Tucci, K; Cosenza, M G

    2008-01-01

    A system of coupled chaotic bistable maps on a lattice with randomly distributed impurities is investigated as a model for studying the phenomenon of phase growth in nonuniform media. The statistical properties of the system are characterized by means of the average size of spatial domains of equivalent spin variables that define the phases. It is found that the rate at which phase domains grow becomes smaller when impurities are present and that the average size of the resulting domains in the inhomogeneous state of the system decreases when the density of impurities is increased. The phase diagram showing regions where homogeneous, heterogeneous, and chessboard patterns occur on the space of parameters of the system is obtained. A critical boundary that separates the regime of slow growth of domains from the regime of fast growth in the heterogeneous region of the phase diagram is calculated. The transition between these two growth regimes is explained in terms of the stability properties of the local phase configurations. Our results show that the inclusion of spatial inhomogeneities can be used as a control mechanism for the size and growth velocity of phase domains forming in spatiotemporal systems. PMID:18351923

  14. Impurity scattering and Friedel oscillations in monolayer black phosphorus

    NASA Astrophysics Data System (ADS)

    Zou, Yong-Lian; Song, Juntao; Bai, Chunxu; Chang, Kai

    2016-07-01

    We study the impurity scattering effect in black phosphorene (BP) in this work. For a single impurity, we calculate the impurity-induced local density of states (LDOS) in momentum space numerically based on a tight-binding Hamiltonian. In real space, we calculate the LDOS and Friedel oscillation analytically. The LDOS shows strong anisotropy in BP. Many impurities in BP are investigated using the T -matrix approximation when the density is low. Midgap states appear in the band gap with peaks in the DOS. The peaks of midgap states are dependent on the impurity potential. For finite positive potential, the impurity tends to bind negative charge carriers and vice versa. The infinite-impurity-potential problem is related to chiral symmetry in BP.

  15. Low impurity concentrations and enhanced confinement in the Lithium Tokamak Experiment (LTX)

    NASA Astrophysics Data System (ADS)

    Boyle, D. P.; Bell, R. E.; Kaita, R.; Majeski, R.; Schmitt, J. C.; Scotti, F.; Biewer, T. M.; Gray, T. K.

    2015-11-01

    Significant improvements in confinement and overall performance have been shown in many devices using lithium wall-coatings, though impurities have often been an issue. Previous results with partial coatings in LTX, a modest-sized, ohmically-heated spherical tokamak, demonstrated energy confinement times exceeding ITER ELMy H-mode scalings. Here we report the results of new experiments with fully lithium coated walls, including first-ever successful operation of a tokamak plasma with a full liquid lithium wall. Energy confinement estimates based on magnetic analysis exceed the ITER98P scaling by 2-4x, and can now be confirmed with electron temperature and density profiles from Thomson scattering. Past attempts at a full liquid Li coating in LTX were unsuccessful, with difficulty achieving breakdown and short, cold, impurity dominated plasmas. Now, spectroscopic measurements in discharges with full liquid coatings indicate low core core impurity concentrations of Li, C, and O. The implications for impurity transport will be discussed. The results for confinement and impurity behavior with solid and liquid lithium on stainless steel surfaces in LTX are relevant to future devices and upgrades with all-metal walls, including NSTX-U. This work is supported by US DOE contracts DE-AC02-09CH11466 and DE- AC05-00OR22725.

  16. Impurity content of reduced-activation ferritic steels and a vanadium alloy

    SciTech Connect

    Klueh, R.L.; Grossbeck, M.L.; Bloom, E.E.

    1997-04-01

    Inductively coupled plasma mass spectrometry was used to analyze a reduced-activation ferritic/martensitic steel and a vanadium alloy for low-level impurities that would compromise the reduced-activation characteristics of these materials. The ferritic steel was from the 5-ton IEA heat of modified F82H, and the vanadium alloy was from a 500-kg heat of V-4Cr-4Ti. To compare techniques for analysis of low concentrations of impurities, the vanadium alloy was also examined by glow discharge mass spectrometry. Two other reduced-activation steels and two commercial ferritic steels were also analyzed to determine the difference in the level of the detrimental impurities in the IEA heat and steels for which no extra effort was made to restrict some of the tramp impurities. Silver, cobalt, molybdenum, and niobium proved to be the tramp impurities of most importance. The levels observed in these two materials produced with present technology exceeded the limits for low activation for either shallow land burial or recycling. The chemical analyses provide a benchmark for the improvement in production technology required to achieve reduced activation; they also provide a set of concentrations for calculating decay characteristics for reduced-activation materials. The results indicate the progress that has been made and give an indication of what must still be done before the reduced-activation criteria can be achieved.

  17. The effect of elemental and hydrocarbon impurities on mercuric iodide gamma ray detector performance

    NASA Astrophysics Data System (ADS)

    Cross, Eilene S.; Buffleben, George; Soria, Ed; James, Ralph; Schieber, Michael; Natarajan, Raj; Gerrish, Vern

    Mercuric iodide is a room temperature semiconductor material that is used for gamma ray and x-ray radiation detection. Mercuric iodide is synthesized from mercuric chloride and potassium iodide and is then purified by a series of melts and sublimation steps and by zone refining. The mercuric iodide is grown into crystals and platelets and then fabricated into detectors. Elemental contamination may be a determining factor in the performance of these detectors. These contaminates may be present in the starting material or may be introduced during, or be unaffected by, the purification, growth or fabrication steps. Methods have been developed for the analysis of trace levels of elemental contamination. Inductively Coupled Plasma/Mass Spectroscopy (ICP/MS), Inductively Coupled Plasma/Optical Emission Spectroscopy (ICP/OES) and Gas Chromatography/Mass Spectroscopy (GC/MS) are used to determine sub ppm levels of many trace elemental impurities. Trace levels of many elemental impurities in the raw mercuric iodide are significantly reduced during the purification and zone refining processes. Though the levels of impurities are reduced, poor performing mercuric iodide detectors have contamination levels remaining or reintroduced which are higher for Ag, Al, Ca, Cu, Mg, Mn, Na, Pb and Zn than detectors with good gamma ray response. This paper will discuss the analytical methodology, the effects of purification on impurity levels, and the correlation between detector performance and impurity levels.

  18. Quantifying Main Trends in Lysozyme Nucleation: The Effect of Precipitant Concentration and Impurities

    NASA Technical Reports Server (NTRS)

    Burke, Michael W.; Judge, Russell A.; Pusey, Marc L.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Full factorial experiment design incorporating multi-linear regression analysis of the experimental data allows the main trends and effects to be quickly identified while using only a limited number of experiments. These techniques were used to identify the effect of precipitant concentration and the presence of an impurity, the physiological lysozyme dimer, on the nucleation rate and crystal dimensions of the tetragonal form of chicken egg white lysozyme. Increasing precipitant concentration was found to decrease crystal numbers, the magnitude of this effect also depending on the supersaturation. The presence of the dimer generally increased nucleation. The crystal axial ratio decreased with increasing precipitant concentration independent of impurity.

  19. Statics and dynamics of atomic dark-bright solitons in the presence of impurities

    SciTech Connect

    Achilleos, V.; Frantzeskakis, D. J.; Kevrekidis, P. G.; Rothos, V. M.

    2011-11-15

    Adopting a mean-field description for a two-component atomic Bose-Einstein condensate, we study the statics and dynamics of dark-bright solitons in the presence of localized impurities. We use adiabatic perturbation theory to derive an equation of motion for the dark-bright soliton center. We show that, counterintuitively, an attractive (repulsive) delta-like impurity, acting solely on the bright-soliton component, induces an effective localized barrier (well) in the effective potential felt by the soliton; this way, dark-bright solitons are reflected from (transmitted through) attractive (repulsive) impurities. Our analytical results for the small-amplitude oscillations of solitons are found to be in good agreement with results obtained via a Bogoliubov-de Gennes analysis and direct numerical simulations.

  20. Identification of impurities and statistical classification of methamphetamine hydrochloride drugs seized in the China

    PubMed Central

    Zhang, Jian Xin; Zhang, Da Ming; Han, Xu Guang

    2008-01-01

    A total of 48 methamphetamine hydrochloride samples from eight seizures were analyzed using gas chromatography–mass spectrometry (GC–MS) and a flame ionization detector (GC–FID). Major impurities detected include 1,2-dimethyl-3-phenylaziridine, Ephedrine/pseudoephedrine, 1,3-dimethyl-2-phenylnaphthalene, 1-benzyl-3-methylnaphthalene. These data are suggestive of ephedrine/pseudoephedrine as the main precursor of the methamphetamine hydrochloride samples seized during 2006–2007. Additionally the presence of 1,3-dimethyl-2-phenylnaphthalene, 1-benzyl-3-methylnaphthalene is indicative that six seizures were synthesized via the more specific ephedrine/hydriodic acid/red phosphorus method. In addition, five impurities were found for the first time in methamphetamine hydrochloride samples. Seventeen impurity peaks were selected from the GC–FID chromatograms. The peak areas of the selected peaks were then grouped for cluster analysis. PMID:19008060

  1. Dynamical critical behavior of the Ziff-Gulari-Barshad model with quenched impurities

    NASA Astrophysics Data System (ADS)

    de Andrade, M. F.; Figueiredo, W.

    2016-08-01

    The simplest model to explain the CO oxidation in some catalytic processes is the Ziff-Gulari-Barshad (ZGB) model. It predicts a continuous phase transition between an active phase and an absorbing phase composed of O atoms. By employing Monte Carlo simulations we investigate the dynamical critical behavior of the model as a function of the concentration of fixed impurities over the catalytic surface. By means of an epidemic analysis we calculate the critical exponents related to the survival probability Ps (t), the number of empty sites nv (t), and the mean square displacement R2 (t). We show that the critical exponents depend on the concentration of impurities over the lattice, even for small values of this quantity. We also show that the exponents do not belong to the Directed Percolation universality class and are in agreement with the Harris criterion since the quenched impurities behave as a weak disorder in the system.

  2. Motion of a Distinguishable Impurity in the Bose Gas: Arrested Expansion Without a Lattice and Impurity Snaking

    NASA Astrophysics Data System (ADS)

    Robinson, Neil J.; Caux, Jean-Sébastien; Konik, Robert M.

    2016-04-01

    We consider the real-time dynamics of an initially localized distinguishable impurity injected into the ground state of the Lieb-Liniger model. Focusing on the case where integrability is preserved, we numerically compute the time evolution of the impurity density operator in regimes far from analytically tractable limits. We find that the injected impurity undergoes a stuttering motion as it moves and expands. For an initially stationary impurity, the interaction-driven formation of a quasibound state with a hole in the background gas leads to arrested expansion—a period of quasistationary behavior. When the impurity is injected with a finite center-of-mass momentum, the impurity moves through the background gas in a snaking manner, arising from a quantum Newton's cradlelike scenario where momentum is exchanged back and forth between the impurity and the background gas.

  3. Motion of a Distinguishable Impurity in the Bose Gas: Arrested Expansion Without a Lattice and Impurity Snaking.

    PubMed

    Robinson, Neil J; Caux, Jean-Sébastien; Konik, Robert M

    2016-04-01

    We consider the real-time dynamics of an initially localized distinguishable impurity injected into the ground state of the Lieb-Liniger model. Focusing on the case where integrability is preserved, we numerically compute the time evolution of the impurity density operator in regimes far from analytically tractable limits. We find that the injected impurity undergoes a stuttering motion as it moves and expands. For an initially stationary impurity, the interaction-driven formation of a quasibound state with a hole in the background gas leads to arrested expansion-a period of quasistationary behavior. When the impurity is injected with a finite center-of-mass momentum, the impurity moves through the background gas in a snaking manner, arising from a quantum Newton's cradlelike scenario where momentum is exchanged back and forth between the impurity and the background gas. PMID:27104716

  4. Motion of a distinguishable Impurity in the Bose gas: Arrested expansion without a lattice and impurity snaking

    DOE PAGESBeta

    Neil J. Robinson; Caux, Jean -Sebastien; Konik, Robert M.

    2016-04-07

    We consider the real-time dynamics of an initially localized distinguishable impurity injected into the ground state of the Lieb-Liniger model. Focusing on the case where integrability is preserved, we numerically compute the time evolution of the impurity density operator in regimes far from analytically tractable limits. We find that the injected impurity undergoes a stuttering motion as it moves and expands. For an initially stationary impurity, the interaction-driven formation of a quasibound state with a hole in the background gas leads to arrested expansion—a period of quasistationary behavior. In conclusion, when the impurity is injected with a finite center-of-mass momentum,more » the impurity moves through the background gas in a snaking manner, arising from a quantum Newton’s cradlelike scenario where momentum is exchanged back and forth between the impurity and the background gas.« less

  5. A mechanistic study of impurity segregation at silicon grain boundaries

    NASA Astrophysics Data System (ADS)

    Käshammer, Peter; Sinno, Talid

    2015-09-01

    The segregation behavior of carbon and oxygen atoms at various silicon grain boundaries was studied using a combination of atomistic simulation and analytical modeling. First, quasi-lattice Grand Canonical Monte Carlo simulations were used to compute segregation isotherms as a function of grain boundary type, impurity atom loading level, and temperature. Next, the atomistic results were employed to regress different analytical segregation models and extract thermodynamic and structural properties. The multilayer Brunauer-Emmett-Teller (BET) isotherm was found to quantitatively capture all the simulation conditions probed in this work, while simpler, single layer models such as the Langmuir-McLean model did not. Some of the BET parameters, namely, the binding free energy of the first adsorption layer and the impurity holding capacity of each layer, were tested for correlation with various measures of grain boundary structure and/or mechanical properties. It was found that certain measures of the atomistic stress distribution correlate strongly with the first-layer binding free energy for substitutional carbon atoms, while common grain boundary identifiers such as sigma value and energy density are not useful in this regard. Preliminary analysis of the more complex case of interstitial oxygen segregation showed that similar measures based on atomistic stress also may be useful here, but more systematic correlative studies are needed to develop a comprehensive picture.

  6. A mechanistic study of impurity segregation at silicon grain boundaries

    SciTech Connect

    Käshammer, Peter; Sinno, Talid

    2015-09-07

    The segregation behavior of carbon and oxygen atoms at various silicon grain boundaries was studied using a combination of atomistic simulation and analytical modeling. First, quasi-lattice Grand Canonical Monte Carlo simulations were used to compute segregation isotherms as a function of grain boundary type, impurity atom loading level, and temperature. Next, the atomistic results were employed to regress different analytical segregation models and extract thermodynamic and structural properties. The multilayer Brunauer–Emmett–Teller (BET) isotherm was found to quantitatively capture all the simulation conditions probed in this work, while simpler, single layer models such as the Langmuir-McLean model did not. Some of the BET parameters, namely, the binding free energy of the first adsorption layer and the impurity holding capacity of each layer, were tested for correlation with various measures of grain boundary structure and/or mechanical properties. It was found that certain measures of the atomistic stress distribution correlate strongly with the first-layer binding free energy for substitutional carbon atoms, while common grain boundary identifiers such as sigma value and energy density are not useful in this regard. Preliminary analysis of the more complex case of interstitial oxygen segregation showed that similar measures based on atomistic stress also may be useful here, but more systematic correlative studies are needed to develop a comprehensive picture.

  7. A review of impurity transport characteristics in the LHD

    NASA Astrophysics Data System (ADS)

    Sudo, Shigeru

    2016-04-01

    The behavior of impurities in the Large Helical Device (LHD) is reviewed based on the knowledge acquired since LHD experiments started in 1998. As a result, a consistent physical picture of impurity transport is obtained in the vast plasma parameter range. The essential points are: (1) the impurity confinement time increases monotonically as the bulk electron density increases in the plasma core; (2) the balance between the friction force and the thermal force on the impurities plays an important role in determining impurity transport in the stochastic layers; (3) a positive electric field leads to outward convection, and a negative electric field generally leads to inward convection (except for the impurity hole case); and (4) in the case of the impurity hole phenomenon, with a high ion temperature plasma and a steep ion temperature gradient, outward convection of the impurities in the plasma core is apparent in spite of the negative electric field. The mechanism for producing outward convection in the impurity hole plasma has not yet been clarified. The effects of the magnetic axis shift and the magnetic island are summarized, and some possible methods for impurity control are also discussed.

  8. Enhanced ionized impurity scattering in nanowires

    NASA Astrophysics Data System (ADS)

    Oh, Jung Hyun; Lee, Seok-Hee; Shin, Mincheol

    2013-06-01

    The electronic resistivity in silicon nanowires is investigated by taking into account scattering as well as the donor deactivation from the dielectric mismatch. The effects of poorly screened dopant atoms from the dielectric mismatch and variable carrier density in nanowires are found to play a crucial role in determining the nanowire resistivity. Using Green's function method within the self-consistent Born approximation, it is shown that donor deactivation and ionized impurity scattering combined with the charged interface traps successfully to explain the increase in the resistivity of Si nanowires while reducing the radius, measured by Björk et al. [Nature Nanotech. 4, 103 (2009)].

  9. Impurities Formed in Artificially Aged Methylhydrazine

    NASA Technical Reports Server (NTRS)

    McClure, Mark B.; Dee, Louis A.; Johnson, Harry T.; Fries, Joseph (Technical Monitor)

    2000-01-01

    A sample of monomethylhydrazine (MMH) meeting MIL-PRF-27404C requirements was split into two portions. One portion was periodically exposed to atmospheric contaminants while stored in clear glass, and the other portion, held as a reference sample, was stored under nitrogen in amber glass. Impurities in both samples were periodically characterized by Gas Chromatograph-Mass Spectrometer (GC-MS) to determine what changes might occur in MMH when it is stored in less than ideal conditions. The qualitative and semi-quantitative results of this study are reported herein.

  10. Electronic structure of magnetic impurities in copper

    SciTech Connect

    Vvedensky, D.D.; Eberhart, M.E.; McHenry, M.E.

    1987-02-01

    We show that the anomalously small impurity exchange splittings obtained from previously reported multiple-scattering X..cap alpha.. cluster calculations for the dilute alloys CuM (M represents a 3d transition metal) were due to incomplete convergence to self-consistency. Proper self-consistent calculations produce exchange splittings that are in excellent agreement with other calculations, which we illustrate with CuMn. We compare in detail the results of our calculations with those obtained with other approaches and discuss briefly the role of many-body effects in the CuM alloy series.

  11. Integrable Two-Impurity Kondo Model

    SciTech Connect

    Schlottmann, P.

    1998-06-01

    The exact solution by means of Bethe{close_quote}s {ital Ansatz} of a variant of the two-impurity Kondo problem is presented. The occupation of the singlet and triplet states, the expectation value {l_angle}{rvec S}{sub 1}{center_dot} {cflx S}{sub 2}{r_angle} , the homogeneous and staggered magnetic field susceptibilities, and the specific heat {gamma} coefficient are studied for the ground state as a function of the Ruderman-Kittel-Kasuya-Yosida{endash}coupling strength. {copyright} {ital 1998} {ital The American Physical Society}

  12. Evaluating additives and impurities in zinc electrowinning

    NASA Astrophysics Data System (ADS)

    Gonzalez-Dominguez, J. A.; Lew, R. W.

    1995-01-01

    The zinc electrowinning (EW) process is very sensitive to the presence of impurities. There is only one EW plant in the world that we know of that operates at moderate current efficiency and deposition times without using any additives. All the others must use them continuously. Additives allow zinc EW to occur at high current efficiencies while suppressing excessive acid mist formation. The study of the electrochemical effects of additives in zinc EW is not straightforward. This article presents a review of the experimental techniques currently used at Cominco Research: Cyclic voltammetry, Hull cells, laboratory and mini-cell electrowinning techniques are all described and their relationship to the industrial operation is discussed.

  13. Quantitative comparison of experimental impurity transport with nonlinear gyrokinetic simulation in an Alcator C-Mod L-mode plasma

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    Nonlinear gyrokinetic simulations of impurity transport are compared to experimental impurity transport for the first time. The GYRO code (Candy and Waltz 2003 J. Comput. Phys. 186 545) was used to perform global, nonlinear gyrokinetic simulations of impurity transport for a standard Alcator C-Mod, L-mode discharge. The laser blow-off technique was combined with soft x-ray measurements of a single charge state of calcium to provide time-evolving profiles of this non-intrinsic, non-recycling impurity over a radial range of 0.0 ⩽ r/a ⩽ 0.6. Experimental transport coefficient profiles and their uncertainties were extracted from the measurements using the impurity transport code STRAHL and rigorous Monte Carlo error analysis. To best assess the agreement of gyrokinetic simulations with the experimental profiles, the sensitivity of the GYRO predicted impurity transport to a wide range of turbulence-relevant plasma parameters was investigated. A direct comparison of nonlinear gyrokinetic simulation and experiment is presented with an in depth discussion of error sources and a new data analysis methodology.

  14. Fractional impurity moments in two-dimensional noncollinear magnets.

    PubMed

    Wollny, Alexander; Fritz, Lars; Vojta, Matthias

    2011-09-23

    We study dilute magnetic impurities and vacancies in two-dimensional frustrated magnets with noncollinear order. Taking the triangular-lattice Heisenberg model as an example, we use quasiclassical methods to determine the impurity contributions to the magnetization and susceptibility. Most importantly, each impurity moment is not quantized but receives nonuniversal screening corrections due to local relief of frustration. At finite temperatures, where bulk long-range order is absent, this implies an impurity-induced magnetic response of Curie form, with a prefactor corresponding to a fractional moment per impurity. We also discuss the behavior in an applied magnetic field, where we find a singular linear-response limit for overcompensated impurities. PMID:22026900

  15. Structural elucation of a novel impurity in rifaximin.

    PubMed

    Liuchao; Maixi; Wangchao; Wan, Chunpeng

    2012-05-01

    Rifaximin is a semi-synthetic rifamycin derivate. It acts on RNA polymerase of the subunit of DNA beta-2 in bacteria to restrain synthesis of RNA leading to antibacterial activity. The purpose of this study was to analyse the structure of the prepared impurity a. We found that the impurity a is the isomeride of impurity G defined in the European Pharmacopoeia. PMID:22764576

  16. Photocurrent in a quantum channel with an impurity

    SciTech Connect

    Margulis, V. A. Pyataev, M. A. Ulyanov, S. N.

    2013-09-15

    The influence of electromagnetic radiation on electron transport in a quantum channel with a single short-range impurity is studied using the generalization of the Landauer-Buettiker method. It is shown that a direct photocurrent is induced in the system in the case of asymmetric impurity location. The dependence of the photocurrent on the electron chemical potential, impurity location, and radiation frequency is studied.

  17. Stark effect of hydrogenic impurities in a quantum box

    NASA Astrophysics Data System (ADS)

    del Castillo-Mussot, Marcelo; Vazquez, Gerardo J.; Mendoza, Carlos I.; Spector, Harold N.

    2004-03-01

    We extend the model of a cubic quantum box proposed by Ribeiro and Latge to carry out a variational calculation of the bindingenergy of impurities in such a structure as function of anelectric field.The binding energy of the impurities increases with the electric field. In addition, the electric field splits the energy of impurities on the faces of the box which are equivalent in the absence of the electric field.

  18. Interaction of infrared light with impurity gels in superfluid helium

    NASA Astrophysics Data System (ADS)

    Izotov, A. N.; Efimov, V. B.

    2011-05-01

    Rapid cooling of an impurity-helium mixture into superfluid helium produces a distinctive soft matter—impurity-helium gel, clusters of which coagulate into nanoparticles. The sizes of the particles and their mutual interaction depend on the nature of the impurity atoms and the impurity-helium coupling. Here we describe the setup of and preliminary results from an experiment to study infrared absorption by a water-helium gel. Comparisons of the infrared absorption spectra of the gel and of water and ice suggests a peculiar interaction among water molecules in a water-helium gel.

  19. Quantum impurities: from mobile Josephson junctions to depletons

    NASA Astrophysics Data System (ADS)

    Schecter, Michael; Gangardt, Dimitri M.; Kamenev, Alex

    2016-06-01

    We overview the main features of mobile impurities moving in one-dimensional superfluid backgrounds by modeling it as a mobile Josephson junction, which leads naturally to the periodic dispersion of the impurity. The dissipation processes, such as radiative friction and quantum viscosity, are shown to result from the interaction of the collective phase difference with the background phonons. We develop a more realistic depleton model of an impurity-hole bound state that provides a number of exact results interpolating between the semiclassical weakly interacting picture and the strongly interacting Tonks–Girardeau regime. We also discuss the physics of a trapped impurity, relevant to current experiments with ultra cold atoms.

  20. Numerical Simulation of mobile BEC-impurity interaction

    NASA Astrophysics Data System (ADS)

    Lausch, Tobias; Grusdt, Fabian; Fleischhauer, Michael; Widera, Artur

    2016-05-01

    Cooling atoms to temperatures, where quantum effects become dominant, has become a standard in cold atom experiments. Especially interactions of quantum baths such as fermi gases and the implementation of impurities, which form fermi polarons, have been studied theoretically and experimentally in detail. However, detailed experiments on the bose polaron and the interaction between impurities and a bose gas are still elusive. We consider a model, where we immerse a single impurity into a BEC, which is described by Bogoliubov approximation. From the master equation, we derived the impurity's momentum resolved scattering and cooling dynamics for numerical simulations. Such cooling processes should enable momentum resolved radio-frequency spectroscopy of the BEC polaron.

  1. HPLC-MS Examination of Impurities in Pentaerythritol Tetranitrate

    NASA Astrophysics Data System (ADS)

    Brown, Geoffrey W.; Giambra, Anna M.

    2014-04-01

    Pentaerythritol tetranitrate (PETN) has trace homolog impurities that can be detected by high-performance liquid chromatography-mass spectrometry. Consideration of observed impurity masses and candidate structures based on known pentaerythritol impurities allows identification of 22 compounds in the data. These are all consistent with either fully nitrated homologs or derivatives substituted with methyl, methoxy, or hydroxyl groups in place of a nitric ester. Examining relative impurity concentrations in three starting batches of PETN and six subsequently processed batches shows that it is possible to use relative concentration profiles as a fingerprint to differentiate batches and follow them through recrystallization steps.

  2. Oxygen impurity radiation from Tokamak-like plasmas

    NASA Technical Reports Server (NTRS)

    Rogerson, J. E.; Davis, J.; Jacobs, V. L.

    1977-01-01

    We have constructed a nonhydrodynamic coronal model for calculating radiation from impurity atoms in a heated plasma. Some recent developments in the calculation of dielectronic recombination rate coefficients and collisional excitation rate coefficients are included. The model is applied to oxygen impurity radiation during the first few milliseconds of a TFR Tokamak plasma discharge, and good agreement with experimental results is obtained. Estimates of total line and continuum radiation from the oxygen impurity are given. It is shown that impurity radiation represents a considerable energy loss.

  3. Topological state engineering by potential impurities on chiral superconductors

    NASA Astrophysics Data System (ADS)

    Kaladzhyan, Vardan; Röntynen, Joel; Simon, Pascal; Ojanen, Teemu

    2016-08-01

    In this work we consider the influence of potential impurities deposited on top of two-dimensional chiral superconductors. As discovered recently, magnetic impurity lattices on an s -wave superconductor may give rise to a rich topological phase diagram. We show that a similar mechanism takes place in chiral superconductors decorated by nonmagnetic impurities, thus avoiding the delicate issue of magnetic ordering of adatoms. We illustrate the method by presenting the theory of potential impurity lattices embedded on chiral p -wave superconductors. While a prerequisite for the topological state engineering is a chiral superconductor, the proposed procedure results in vistas of nontrivial descendant phases with different Chern numbers.

  4. Tuning emergent magnetism in a Hund's impurity.

    PubMed

    Khajetoorians, A A; Valentyuk, M; Steinbrecher, M; Schlenk, T; Shick, A; Kolorenc, J; Lichtenstein, A I; Wehling, T O; Wiesendanger, R; Wiebe, J

    2015-11-01

    The recently proposed concept of a Hund's metal--a metal in which electron correlations are driven by Hund's rule coupling-can be used to explain the exotic magnetic and electronic behaviour of strongly correlated electron systems of multi-orbital metallic materials. Tuning the abundance of parameters that determine these materials is, however, experimentally challenging. Here, we show that the basic constituent of a Hund's metal--a Hund's impurity--can be realized using a single iron atom adsorbed on a platinum surface, a system that comprises a magnetic moment in the presence of strong charge fluctuations. The magnetic properties can be controlled by using the tip of a scanning tunnelling microscope to change the binding site and degree of hydrogenation of the 3d transition-metal atom. We are able to experimentally explore a regime of four almost degenerate energy scales (Zeeman energy, temperature, Kondo temperature and magnetic anisotropy) and probe the magnetic excitations with the microscope tip. The regime of our Hund's impurity can be tuned from an emergent magnetic moment to a multi-orbital Kondo state, and the system could be used to test predictions of advanced many-body theories for non-Fermi liquids in quantum magnets or unconventional superconductors. PMID:26344182

  5. Particle fueling and impurity control in PDX

    SciTech Connect

    Fonck, R.J.; Bell, M.; Bol, K.; Budny, R.; Couture, P.; Darrow, D.; Dylla, H.; Goldston, R.; Grek, B.; Hawryluk, R.

    1984-12-01

    Fueling requirements and impurity levels in neutral-beam-heated discharges in the PDX tokamak have been compared for plasmas formed with conventional graphite rail limiters, a particle scoop limiter, and an open or closed poloidal divertor. Gas flows necessary to obtain a given density are highest for diverted discharges and lowest for the scoop limiter. Hydrogen pellet injection provides an efficient alternate fueling technique, and a multiple pellet injector has produced high density discharges for an absorbed neutral beam power of up to 600 kW, above which higher speeds or more massive pellets are required for penetration to the plasma core. Power balance studies indicate that 30 to 40% of the total input power is radiated while approx. 15% is absorbed by the limiting surface, except in the open divertor case, where 60% flows to the neutralizer plate. In all operating configurations, Z/sub eff/ usually rises at the onset of neutral beam injection. Both open divertor plasmas and those formed on a well conditioned water-cooled limiter have Z/sub eff/ less than or equal to 2 at the end of neutral injection. A definitive comparison of divertors and limiters for impurity control purposes requires longer beam pulses or higher power levels than available on present machines.

  6. Deuterium permeation through copper with trapping impurities

    NASA Astrophysics Data System (ADS)

    Mitchell, D. J.; Harris, J. M.; Patrick, R. C.; Boespflug, E. P.; Beavis, L. C.

    1982-02-01

    The time dependence of the deuterium permeation rate through impurity-doped copper membranes was measured in the temperature range 300-700 °C. Copper membranes that were doped with Er, Zr, and Ti all exhibited permeabilities that were nearly equal to pure copper, but the apparent diffusivities were smaller than those for pure copper by factors of 10-100 over the experimental temperature range. The permeation characteristics of these alloys appear to be altered from those for pure copper due to trapping of deuterium at sites that are associated with the impurity atoms. It is shown that the deuterium permeation rate through the copper alloys can be expressed in an analytical form that is analogous to that for pure copper, except that the apparent diffusivity takes on a value which depends on the trap concentration and binding energy for deuterium. The binding energies that are calculated for the alloys are used to determine the lag time which is required for deuterium or hydrogen to permeate through initially evacuated membranes. The lag times for copper alloys containing about 1% Er, Zr, or Ti are many orders of magnitude longer than for pure copper at room temperature. Copper alloys containing Cr do not appear to exhibit deuterium trapping. Nuclear reaction and backscattering analyses were used to help determine the effect or surface oxides on the permeation measurements.

  7. Quantification of active pharmaceutical ingredient and impurities in sildenafil citrate obtained from the Internet

    PubMed Central

    Nutan, Mohammad T.; Dodla, Uday Krishna Reddy

    2014-01-01

    Background: The accessibility of prescription drugs produced outside of the United States, most notably sildenafil citrate (innovator product, Viagra®), has been made much easier by the Internet. Of greatest concern to clinicians and policymakers is product quality and patient safety. The US Food and Drug Administration (FDA) has issued warnings to potential buyers that the safety of drugs purchased from the Internet cannot be guaranteed, and may present a health risk to consumers from substandard products. Objective: The objective of this study was to determine whether generic sildenafil citrate tablets from international markets obtained via the Internet are equivalent to the US innovator product regarding major aspects of pharmaceutical quality: potency, accuracy of labeling, and presence and level of impurities. This will help identify aspects of drug quality that may impact public health risks. Methods: A total of 15 sildenafil citrate tablets were obtained for pharmaceutical analysis: 14 generic samples from international Internet pharmacy websites and the US innovator product. According to US Pharmacopeial guidelines, tablet samples were tested using high-performance liquid chromatography for potency of active pharmaceutical ingredient (API) and levels of impurities (impurities A, B, C, and D). Impurity levels were compared with International Conference on Harmonisation (ICH) limits. Results: Among the 15 samples, 4 samples possessed higher impurity B levels than the ICH qualification threshold, 8 samples possessed higher impurity C levels than the ICH qualification threshold, and 4 samples possessed more than 1% impurity quantity of maximum daily dose (MDD). For API, 6 of the samples failed to fall within the 5% assay limit. Conclusions: Quality assurance tests are often used to detect formulation defects of drug products during the manufacturing and/or storage process. Results suggest that manufacturing standards for sildenafil citrate generic drug

  8. Development of RP UPLC-TOF/MS, stability indicating method for omeprazole and its related substances by applying two level factorial design; and identification and synthesis of non-pharmacopoeial impurities.

    PubMed

    Jadhav, Sushant Bhimrao; Kumar, C Kiran; Bandichhor, Rakeshwar; Bhosale, P N

    2016-01-25

    A new UPLC-TOF/MS compatible, reverse phase-stability indicating method was developed for determination of Omeprazole (OMP) and its related substances in pharmaceutical dosage forms by implementing Design of Experiment (DoE) i.e. two level full factorial Design (2(3)+3 center points=11 experiments) to understand the Critical Method Parameters (CMP) and its relation with Critical Method Attribute (CMA); to ensure robustness of the method. The separation of eleven specified impurities including conversion product of OMP related compound F (13) and G (14) i.e. Impurity-I (1), OMP related compound-I (11) and OMP 4-chloro analog (12) was achieved in a single method on Acquity BEH shield RP18 100 × 2.1 mm, 1.7 μm column, with inlet filter (0.2 μm) using gradient elution and detector wavelength at 305 nm and validated in accordance with ICH guidelines and found to be accurate, precise, reproducible, robust and specific. The drug was found to degrade extensively in heat, humidity and acidic conditions and forms unknown degradation products during stability studies. The same method was used for LC-MS analysis to identify m/z and fragmentation of maximum unknown impurities (Non-Pharmacopoeial) i.e. Impurity-I (1), Impurity-III (3), Impurity-V (5) and Impurity-VIII (9) formed during stability studies. Based on the results, degradation pathway for the drug has been proposed and synthesis of identified impurities i.e. impurities (Impurity-I (1), Impurity-III (3), Impurity-V (5) and Impurity-VIII (9)) are discussed in detail to ensure in-depth understanding of OMP and its related impurities and optimum performance during lifetime of the product. PMID:26600119

  9. Twin Roll Casting of Al-Mg Alloy with High Added Impurity Content

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Hari Babu, N.; Scamans, G. M.; Fan, Z.; O'Reilly, K. A. Q.

    2014-06-01

    The microstructural evolution during twin roll casting (TRC) and downstream processing of AA5754 Al alloy with high added impurity content have been investigated. Strip casts with a high impurity content resulted in coarse α-Al grains and complex secondary phases. The grain size and centerline segregation reduced significantly on the addition of Al-Ti-B grain refiner (GR). Coarse-dendrite arm spacing (DAS) "floating" grains are observed in the impure alloy (IA) with higher volume in the GR strips. Two-dimensional (2D) metallographic analysis of the as-cast strip suggests that secondary phases (Fe-bearing intermetallics and Mg2Si) are discrete and located at the α-Al cell/grain boundaries, while three-dimensional (3D) analysis of extracted particles revealed that they were intact, well interconnected, and located in interdendritic regions. Homogenizing heat treatment of the cast strip breaks the interconnective networks and modifies the secondary phases to a more equiaxed morphology. During rolling, the equiaxed secondary phases align along the rolling direction. X-ray diffraction (XRD) analysis suggests that α-Al(FeMn)Si and Mg2Si are the predominant secondary phases that are formed during casting and remain throughout the downstream processing of the GR-IA. The high-impurity sheet processed from TRC resulted in superior strength and ductility over the sheet processed from small book mold ingot casting. The current study has shown that the TRC process can tolerate higher impurity levels and produce formable sheets from the recycled aluminum for structural applications.

  10. Systematic Study of Trace Radioactive Impurities in Candidate Construction Materials for EXO-200

    SciTech Connect

    Leonard, D.S.; Grinberg, P.; Weber, P.; Baussan, E.; Djurcic, Z.; Keefer, G.; Piepke, A.; Pocar, A.; Vuilleumier, J.-L.; Vuilleumier, J.-M.; Akimov, D.; Bellerive, A.; Bowcock, M.; Breidenbach, M.; Burenkov, A.; Conley, R.; Craddock, W.; Danilov, M.; DeVoe, R.; Dixit, M.; Dolgolenko, A.; /Alabama U. /NRC-INMS /Neuchatel U. /Stanford U., Phys. Dept. /SLAC /Colorado State U. /Laurentian U. /Maryland U. /UC, Irvine

    2007-10-24

    The Enriched Xenon Observatory (EXO) will search for double beta decays of 136Xe. We report the results of a systematic study of trace concentrations of radioactive impurities in a wide range of raw materials and finished parts considered for use in the construction of EXO-200, the first stage of the EXO experimental program. Analysis techniques employed, and described here, include direct gamma counting, alpha counting, neutron activation analysis, and high-sensitivity mass spectrometry.