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Sample records for process related impurities

  1. Strategies for the investigation and control of process-related impurities in drug substances.

    PubMed

    Argentine, Mark D; Owens, Paul K; Olsen, Bernard A

    2007-01-10

    The understanding, identification, quantification and control of impurities in drug substances are essential as new molecular entities are evaluated in clinical development. As chemical processes used to produce drug substances mature from the early phases of development through registration, a concomitant maturing of process-related impurity understanding and control is required. This paper outlines strategies available to pharmaceutical scientists to aid in that understanding. Methodology aspects for impurity investigations are discussed along with an emphasis on understanding the origin and fate of impurities to guide decisions on process controls and specifications. Orthogonal analytical approaches for impurity investigations to provide a complete understanding of a drug substance impurity profile and to aid chemical process development are described. Special considerations necessary for stereochemical impurity investigations are also discussed. Considerations for control of toxic impurities include sensitive and selective analytical methodology and determination of the process capability for removing the impurity. A case study is given where routine analytical testing for a toxic impurity was not required because a high impurity rejection efficiency of the synthetic process was demonstrated. Quality assessment of starting materials from multiple sources and the impact of starting material impurities on the impurity profile of the drug substance are discussed with illustrative examples. Knowledge gained from these investigations provides a sound basis for setting specifications for impurities in key starting materials. PMID:17189658

  2. Isolation and characterization of process-related impurities and degradation products in larotaxel.

    PubMed

    Che, Xin; Shen, Li; Xu, Hui; Liu, Ke

    2011-07-15

    The isolation and characterization of the process related impurities and degradation products of larotaxel drug substance were described. Forced degradation of larotaxel was carried out under acidic, basic, oxidation, light and thermal conditions to assess the nature of the impurities. The pure impurities were obtained by semi-preparative LC isolation and analyzed by NMR and MS. The structures of impurities were confirmed as 7,8-cyclopropyl baccatin III, 10-deacetyl larotaxel, 10-deacetyl-7, 8-cyclopropyl baccatin III, 7-acetyl-8-methyl larotaxel and 2',13-bissidechain larotaxel.

  3. Synthesis and Characterization of Process-Related Impurities of Antidiabetic Drug Linagliptin.

    PubMed

    Huang, Yiwen; He, Xiaoqing; Wu, Taizhi; Zhang, Fuli

    2016-01-01

    Linagliptin, a xanthine derivative, is a highly potent, selective, long-acting and orally bioavailable DPP-4 inhibitor for the treatment of type 2 diabetes. During the process development of linagliptin, five new process-related impurities were detected by high performance liquid chromatography (HPLC). All these impurities were identified, synthesized, and subsequently characterized by their respective spectral data (MS, HRMS, ¹H-NMR, (13)C-NMR and IR) as described in this article. The identification of these impurities should be useful for quality control and the validation of the analytical method in the manufacture of linagliptin. PMID:27517889

  4. Heparins: process-related physico-chemical and compositional characteristics, fingerprints and impurities.

    PubMed

    Liverani, Lino; Mascellani, Giuseppe; Spelta, Franco

    2009-11-01

    During the past 25 years, heparin extraction and purification processes have changed. The results of these changes are reflected by the continuous increase in potency of the International Standard for heparin. This increase is due not only to a higher purity, but also to a number of changes in the physico-chemical characteristics of heparin. For long time, all these changes have been disregarded as non-critical by regulatory authorities. Heparin marketing authorisation was reviewed only two years ago and Pharmacopoeia monographs were reviewed just for the addition of new tests, mainly aimed at tackling the oversulfated chondroitin sulfate (OSCS) crisis. Currently, heparin monographs are again under revision. Such changes, different for each manufacturer, have caused a further increase in the heterogeneity of individual batches of heparin. This review aims at showing that chemical, physical and biological characteristics of heparin (such as disaccharide composition, amount of low sulfated and high sulfated sequences, molecular weight profiles [MW], activities, structural artifacts, fingerprints and glycosaminoglycans impurities) are all process-dependent and may significantly vary when different processes are used to minimise the content of dermatan sulfate. The wide heterogeneity of the physico-chemical characteristics of currently marketed heparin and the lack of suitable and shareable reference standards for the identification/quantification of process-related impurities caused, and are still causing, heated debates among scientific institutions, companies and authorities. PMID:19888518

  5. Identification, characterization, and high-performance liquid chromatography quantification of process-related impurities in vonoprazan fumarate.

    PubMed

    Liu, Lei; Cao, Na; Ma, Xingling; Xiong, Kaihe; Sun, Lili; Zou, Qiaogen

    2016-04-01

    High-performance liquid chromatography analysis of vonoprazan fumarate, a novel proton pump inhibitor drug revealed six impurities. These were identified by liquid chromatography with mass spectrometry. Further, the structures of the impurities were confirmed by synthesis followed by characterization by mass spectrometry, NMR spectroscopy, and infrared spectroscopy. On the basis of these data and knowledge of the synthetic scheme of vonoprazan fumarate, the previously unknown impurity was identified as 1-[5-(2-fluorophenyl)-1-(pyridin-3-ylsulfonyl)-1H-pyrrol-3-yl]-N-methyldimethylamine, which is a new compound. The possible mechanisms by which these impurities were formed were also discussed. A high-performance liquid chromatography method was optimized in order to separate, selectively detect, and quantify all process-related impurities of vonoprazan fumarate. The presented method has been validated in terms of linearity, limits of detection, and quantification, and response factors and, therefore, is highly suitable for routine analysis of vonoprazan fumarate related substances as well as stability studies. PMID:26843471

  6. Identification, characterization, and high-performance liquid chromatography quantification of process-related impurities in vonoprazan fumarate.

    PubMed

    Liu, Lei; Cao, Na; Ma, Xingling; Xiong, Kaihe; Sun, Lili; Zou, Qiaogen

    2016-04-01

    High-performance liquid chromatography analysis of vonoprazan fumarate, a novel proton pump inhibitor drug revealed six impurities. These were identified by liquid chromatography with mass spectrometry. Further, the structures of the impurities were confirmed by synthesis followed by characterization by mass spectrometry, NMR spectroscopy, and infrared spectroscopy. On the basis of these data and knowledge of the synthetic scheme of vonoprazan fumarate, the previously unknown impurity was identified as 1-[5-(2-fluorophenyl)-1-(pyridin-3-ylsulfonyl)-1H-pyrrol-3-yl]-N-methyldimethylamine, which is a new compound. The possible mechanisms by which these impurities were formed were also discussed. A high-performance liquid chromatography method was optimized in order to separate, selectively detect, and quantify all process-related impurities of vonoprazan fumarate. The presented method has been validated in terms of linearity, limits of detection, and quantification, and response factors and, therefore, is highly suitable for routine analysis of vonoprazan fumarate related substances as well as stability studies.

  7. Isolation and characterization of degradation products of citalopram and process-related impurities using RP-HPLC.

    PubMed

    Rao, Ramisetti Nageswara; Raju, Ale Narasa; Narsimha, Ramaram

    2008-06-01

    A reversed-phase high-performance liquid chromatographic method for simultaneous separation and determination of citalopram hydrobromide and its process impurities in bulk drugs and pharmaceutical formulations was developed. The separation was accomplished on an Inertsil ODS 3V (250x4.6 mm; particle size 5 mum) column using 0.3% diethylamine (pH = 4.70) and methanol/acetonitrile (55:45 v/v) as mobile phase in a gradient elution mode. The eluents were monitored by a photodiode array detector set at 225 nm. The chromatographic behavior of all the related substances was examined under variable conditions of different solvents, buffer concentrations, and pH. The method was validated in terms of accuracy, precision, and linearity. The method could be of use not only for rapid and routine evaluation of the quality of citalopram in bulk drug manufacturing units but also for the detection of its impurities in pharmaceutical formulations. Three unknown impurities were consistently observed during the analysis of different batches of citalopram. Forced degradation of citalopram was carried out under thermal, photo, acidic, alkaline, and peroxide conditions. The degradation products and unknown impurities were isolated and characterized by ESI-MS/MS, (1)H NMR, and FT-IR spectroscopy.

  8. Isolation and characterization of degradation products of citalopram and process-related impurities using RP-HPLC.

    PubMed

    Rao, Ramisetti Nageswara; Raju, Ale Narasa; Narsimha, Ramaram

    2008-06-01

    A reversed-phase high-performance liquid chromatographic method for simultaneous separation and determination of citalopram hydrobromide and its process impurities in bulk drugs and pharmaceutical formulations was developed. The separation was accomplished on an Inertsil ODS 3V (250x4.6 mm; particle size 5 mum) column using 0.3% diethylamine (pH = 4.70) and methanol/acetonitrile (55:45 v/v) as mobile phase in a gradient elution mode. The eluents were monitored by a photodiode array detector set at 225 nm. The chromatographic behavior of all the related substances was examined under variable conditions of different solvents, buffer concentrations, and pH. The method was validated in terms of accuracy, precision, and linearity. The method could be of use not only for rapid and routine evaluation of the quality of citalopram in bulk drug manufacturing units but also for the detection of its impurities in pharmaceutical formulations. Three unknown impurities were consistently observed during the analysis of different batches of citalopram. Forced degradation of citalopram was carried out under thermal, photo, acidic, alkaline, and peroxide conditions. The degradation products and unknown impurities were isolated and characterized by ESI-MS/MS, (1)H NMR, and FT-IR spectroscopy. PMID:18481321

  9. Isolation and characterization of a potential process related impurity of phenazopyridine HCl by preparative HPLC followed by MS-MS and 2D-NMR spectroscopy.

    PubMed

    Rao, R Nageswara; Maurya, Pawan K; Raju, A Narasa

    2009-07-12

    During the process development of phenazopyridine HCl bulk drug, a potential impurity was detected in the routine impurity profiles by HPLC. Using MS-MS and multidimensional NMR techniques, the trace level impurity was unambiguously identified to be 3-phenyl-5-phenylazo-pyridine-2,6-diamine after its isolation from phenazopyridine HCl by semi-preparative HPLC. The formation of the impurity was discussed. To our knowledge, it is a novel impurity not reported elsewhere.

  10. Development and validation of a selective, sensitive and stability indicating UPLC-MS/MS method for rapid, simultaneous determination of six process related impurities in darunavir drug substance.

    PubMed

    A, Vijaya Bhaskar Reddy; Yusop, Zulkifli; Jaafar, Jafariah; Aris, Azmi B; Majid, Zaiton A; Umar, Khalid; Talib, Juhaizah

    2016-09-01

    In this study a sensitive and selective gradient reverse phase UPLC-MS/MS method was developed for the simultaneous determination of six process related impurities viz., Imp-I, Imp-II, Imp-III, Imp-IV, Imp-V and Imp-VI in darunavir. The chromatographic separation was performed on Acquity UPLC BEH C18 (50 mm×2.1mm, 1.7μm) column using gradient elution of acetonitrile-methanol (80:20, v/v) and 5.0mM ammonium acetate containing 0.01% formic acid at a flow rate of 0.4mL/min. Both negative and positive electrospray ionization (ESI) modes were operated simultaneously using multiple reaction monitoring (MRM) for the quantification of all six impurities in darunavir. The developed method was fully validated following ICH guidelines with respect to specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, robustness and sample solution stability. The method was able to quantitate Imp-I, Imp-IV, Imp-V at 0.3ppm and Imp-II, Imp-III, and Imp-VI at 0.2ppm with respect to 5.0mg/mL of darunavir. The calibration curves showed good linearity over the concentration range of LOQ to 250% for all six impurities. The correlation coefficient obtained was >0.9989 in all the cases. The accuracy of the method lies between 89.90% and 104.60% for all six impurities. Finally, the method has been successfully applied for three formulation batches of darunavir to determine the above mentioned impurities, however no impurity was found beyond the LOQ. This method is a good quality control tool for the trace level quantification of six process related impurities in darunavir during its synthesis.

  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. Development and validation of a liquid chromatographic method for monitoring of process-related synthetic organic impurities of profenofos in technical products.

    PubMed

    Nageswara Rao, R; Naga Raju, D; Venkateswarlu, N; Vittal Rao, B; Parvathi, N; Manjula, A; Reddy, G N; Gawali, P B; Sreekanth, M; Nageswara Rao, P

    2003-09-01

    A simple and rapid reversed-phase high-performance liquid chromatographic method for the monitoring of process-related synthetic organic impurities of profenofos (PFS) is developed. Impurities are separated and determined on a reversed-phase Hypersil C(18) column using gradient elution of 50 mM ammonium formate buffer-acetonitrile as a mobile phase and detection at 230 nm at ambient temperature. The method is validated with respect to accuracy, precision, linearity, and limits of detection and quantitation. The method is found to be suitable not only for monitoring the reactions involved in the process development of PFS, but also quality assurance, as it can detect impurities at the level of 1.5 x 10(-8) g. PMID:14558934

  13. A validated stability-indicative UPLC method for nilotinib hydrochloride for the determination of process-related and degradation impurities.

    PubMed

    Kondra, Sudhakar Babu; Madireddy, Venkataramanna; Chilukuri, Mohanareddy; Papadasu, Narayanareddy; Jonnalagadda, Latha

    2014-09-01

    A novel stability-indicating ultra performance liquid chromatographic (UPLC) method has been developed for quantitative determination of nilotinib hydrochloride in active pharmaceutical ingredients along with four impurities (imp-1, imp-2, imp-3 and imp-4). The method is applicable to the quantification of related compounds and assay of nilotinib hydrochloride drug. Efficient chromatographic separation was achieved on a Shim-pack XR-ODS II, 75 × 3.0 mm, 1.8-µm column with a gradient mobile phase combination. Quantification was carried at 260 nm at a flow rate of 0.6 mL min(-1). Stress degradation conditions were established for nilotinib hydrochloride by subjecting it to acid, base, oxidation, humidity, thermal and photolysis. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 97.0%. The developed UPLC method was validated according to the present International Conference on Harmonisation guidelines for specificity, detection limit, quantitation limit, linearity, accuracy, precision, intermediate precision and robustness. The resolution between nilotinib hydrochloride and four potential impurities is found to be >2.0. Regression analysis shows as r value (correlation coefficient) of >0.999 for nilotinib hydrochloride and four potential impurities.

  14. Development of a Validated LC Method for Separation of Process-Related Impurities Including the R-Enantiomer of S-Pramipexole on Polysaccharide Chiral Stationary Phases.

    PubMed

    Ramisetti, Nageswara Rao; Kuntamukkala, Ramakrishna; Arnipalli, Manikanta Swamy

    2015-07-01

    Despite the availability of a few methods for individual separation of S-pramipexole from its process-related impurities, no common liquid chromatography (LC) method is reported so far in the literature. The present article describes the development of a single-run LC method for simultaneous determination of S-pramipexole and its enantiomeric and process-related impurities on a Chiralpak AD-H (150 x 4.6 mm, 5μm) column using n-hexane/ethanol/n-butylamine (75:25:0.1 v/v/v) as a mobile phase in an isocratic mode of elution at a flow rate of 1.2 ml/min at 30°C. The chromatographic eluents were monitored at a wavelength of 260 nm using a photodiode array detector. Excellent enantioseparation with good resolutions (Rs ≥ 2.88) and peak shapes (As ≤ 1.21) for all analytes was achieved. The proposed method was validated according to International Conference Harmonization (ICH) guidelines in terms of accuracy, precision, sensitivity, and linearity. Limits of quantification of impurities (0.25-0.55 μg/ml) indicate the highest sensitivity achievable by the proposed method. The method has an advantage of selectivity and suitability for routine determination of not only chiral impurity but also all possible related substances in active pharmaceutical ingredients of S-pramipexole.

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

    PubMed

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

    2015-08-01

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

  16. A validated stability-indicating RP-HPLC method for levofloxacin in the presence of degradation products, its process related impurities and identification of oxidative degradant.

    PubMed

    Lalitha Devi, M; Chandrasekhar, K B

    2009-12-01

    The objective of current study was to develop a validated specific stability indicating reversed-phase liquid chromatographic method for the quantitative determination of levofloxacin as well as its related substances determination in bulk samples, pharmaceutical dosage forms in the presence of degradation products and its process related impurities. Forced degradation studies were performed on bulk sample of levofloxacin as per ICH prescribed stress conditions using acid, base, oxidative, water hydrolysis, thermal stress and photolytic degradation to show the stability indicating power of the method. Significant degradation was observed during oxidative stress and the degradation product formed was identified by LCMS/MS, slight degradation in acidic stress and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from forced degradation studies and the impurity spiked solution. Good resolution between the peaks corresponds to process related impurities and degradation products from the analyte were achieved on ACE C18 column using the mobile phase consists a mixture of 0.5% (v/v) triethyl amine in sodium dihydrogen orthophosphate dihydrate (25 mM; pH 6.0) and methanol using a simple linear gradient. The detection was carried out at 294 nm. The limit of detection and the limit of quantitation for the levofloxacin and its process related impurities were established. The stressed test solutions were assayed against the qualified working standard of levofloxacin and the mass balance in each case was in between 99.4 and 99.8% indicating that the developed LC method was stability indicating. Validation of the developed LC method was carried out as per ICH requirements. The developed LC method was found to be suitable to check the quality of bulk samples of levofloxacin at the time of batch release and also during its stability studies (long term and accelerated stability).

  17. A validated stability-indicating LC method for acetazolamide in the presence of degradation products and its process-related impurities.

    PubMed

    Srinivasu, Prabha; Subbarao, Devarakonda V; Vegesna, Raju V K; Sudhakar Babu, K

    2010-05-01

    The objective of the current study was to develop a validated, specific and stability-indicating reverse phase liquid chromatographic method for the quantitative determination of acetazolamide and its related substances. The determination was done for an active pharmaceutical ingredient, its pharmaceutical dosage form in the presence of degradation products, and its process-related impurities. The drug was subjected to stress conditions of hydrolysis (acid and base), oxidation, photolysis and thermal degradation as per International Conference on Harmonization (ICH) prescribed stress conditions to show the stability-indicating power of the method. Significant degradation was observed during acid and base hydrolysis, and the major degradant was identified by LC-MS, FTIR and (1)H/(13)C NMR spectral analysis. The chromatographic conditions were optimized using an impurity-spiked solution and the generated samples were used for forced degradation studies. In the developed HPLC method, the resolution between acetazolamide and, its process-related impurities (namely imp-1, imp-2, imp-3, imp-4 and its degradation products) was found to be greater than 2. The chromatographic separation was achieved on a C18, 250mmx4.6mm, 5microm column. The LC method employed a linear gradient elution, and the detection wavelength was set at 254nm. The stress samples were assayed against a qualified reference standard and the mass balance was found to be close to 99.6%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.

  18. Four process-related potential new impurities in ticagrelor: Identification, isolation, characterization using HPLC, LC/ESI-MS(n), NMR and their synthesis.

    PubMed

    Kumar, Neeraj; Devineni, Subba Rao; Gajjala, Prasad Reddy; Gupta, Dharmendra Kumar; Bhat, Sandesh; Kumar, Rajesh; Dubey, Shailendra Kumar; Kumar, Pramod

    2016-02-20

    Five process-related impurities were detected in the range of 0.08-0.22% in ticagrelor laboratory batches by HPLC and LC-MS methods. These impurities were named as TIC Imp-I, -II, -III, -IV and -V. Four of these impurities, TIC Imp-I to -IV were unknown and have not been reported previously. Based on LC-ESI/MS(n) study, the chemical structures of new impurities were presumed as (1S,2S,3S,5S)-3-(2-hydroxyethoxy)-5-(7-amino-5-(propylthio)-3H-[1,2,3]triazolo[4,5-d] pyrimidin-3-yl)cyclopentane-1,2-diol (TIC Imp-I), (1S,2S,3S,5S)-3-(7-((1R,2S)-2-(3,4-difluorophenyl)cyclopropylamino)-5-(propylsulfinyl)-3H-[1,2,3]triazolo [4,5-d]pyrimidin-3-yl)-5-(2-hydroxyethoxy)cyclopentane-1,2-diol (TIC Imp-II), (1S,2R,3S,4S)-4-(7-((1R,2S)-2-(3,4-difluorophenyl)cyclopropylamino)-5-(propylthio)-3H-[1,2,3]triazolo[4,5-d]pyrimidin-3-yl)cyclopentane-1,2,3-triol (TIC Imp-III) and (3S,5S)-3-(7-((1R,2S)-2-(3,4-difluorophenyl)cyclopropylamino)-5-(propylthio)-3H-[1,2,3]triazolo[4,5-d]pyrimidin-3-yl)-5-(2-hydroxyethoxy)cyclopentane-1,2-diol (TIC Imp-IV). The unknown impurities were isolated from enriched crude sample by column chromatography and preparative HPLC. The complete spectral analysis, MS, 1D NMR ((1)H, (13)C and DEPT), 2D NMR (HSQC and HMBC) and IR confirmed the proposed chemical structures of impurities. Identification, isolation, structural characterization, prospects for the formation of impurities and their synthesis were first reported in this paper. PMID:26760243

  19. Automated statistical experimental design approach for rapid separation of coenzyme Q10 and identification of its biotechnological process related impurities using UHPLC and UHPLC-APCI-MS.

    PubMed

    Talluri, Murali V N Kumar; Kalariya, Pradipbhai D; Dharavath, Shireesha; Shaikh, Naeem; Garg, Prabha; Ramisetti, Nageswara Rao; Ragampeta, Srinivas

    2016-09-01

    A novel ultra high performance liquid chromatography method development strategy was ameliorated by applying quality by design approach. The developed systematic approach was divided into five steps (i) Analytical Target Profile, (ii) Critical Quality Attributes, (iii) Risk Assessments of Critical parameters using design of experiments (screening and optimization phases), (iv) Generation of design space, and (v) Process Capability Analysis (Cp) for robustness study using Monte Carlo simulation. The complete quality-by-design-based method development was made automated and expedited by employing sub-2 μm particles column with an ultra high performance liquid chromatography system. Successful chromatographic separation of the Coenzyme Q10 from its biotechnological process related impurities was achieved on a Waters Acquity phenyl hexyl (100 mm × 2.1 mm, 1.7 μm) column with gradient elution of 10 mM ammonium acetate buffer (pH 4.0) and a mixture of acetonitrile/2-propanol (1:1) as the mobile phase. Through this study, fast and organized method development workflow was developed and robustness of the method was also demonstrated. The method was validated for specificity, linearity, accuracy, precision, and robustness in compliance to the International Conference on Harmonization, Q2 (R1) guidelines. The impurities were identified by atmospheric pressure chemical ionization-mass spectrometry technique. Further, the in silico toxicity of impurities was analyzed using TOPKAT and DEREK software. PMID:27488256

  20. Automated statistical experimental design approach for rapid separation of coenzyme Q10 and identification of its biotechnological process related impurities using UHPLC and UHPLC-APCI-MS.

    PubMed

    Talluri, Murali V N Kumar; Kalariya, Pradipbhai D; Dharavath, Shireesha; Shaikh, Naeem; Garg, Prabha; Ramisetti, Nageswara Rao; Ragampeta, Srinivas

    2016-09-01

    A novel ultra high performance liquid chromatography method development strategy was ameliorated by applying quality by design approach. The developed systematic approach was divided into five steps (i) Analytical Target Profile, (ii) Critical Quality Attributes, (iii) Risk Assessments of Critical parameters using design of experiments (screening and optimization phases), (iv) Generation of design space, and (v) Process Capability Analysis (Cp) for robustness study using Monte Carlo simulation. The complete quality-by-design-based method development was made automated and expedited by employing sub-2 μm particles column with an ultra high performance liquid chromatography system. Successful chromatographic separation of the Coenzyme Q10 from its biotechnological process related impurities was achieved on a Waters Acquity phenyl hexyl (100 mm × 2.1 mm, 1.7 μm) column with gradient elution of 10 mM ammonium acetate buffer (pH 4.0) and a mixture of acetonitrile/2-propanol (1:1) as the mobile phase. Through this study, fast and organized method development workflow was developed and robustness of the method was also demonstrated. The method was validated for specificity, linearity, accuracy, precision, and robustness in compliance to the International Conference on Harmonization, Q2 (R1) guidelines. The impurities were identified by atmospheric pressure chemical ionization-mass spectrometry technique. Further, the in silico toxicity of impurities was analyzed using TOPKAT and DEREK software.

  1. Analytical control of process impurities in Pazopanib hydrochloride by impurity fate mapping.

    PubMed

    Li, Yan; Liu, David Q; Yang, Shawn; Sudini, Ravinder; McGuire, Michael A; Bhanushali, Dharmesh S; Kord, Alireza S

    2010-08-01

    Understanding the origin and fate of organic impurities within the manufacturing process along with a good control strategy is an integral part of the quality control of drug substance. Following the underlying principles of quality by design (QbD), a systematic approach to analytical control of process impurities by impurity fate mapping (IFM) has been developed and applied to the investigation and control of impurities in the manufacturing process of Pazopanib hydrochloride, an anticancer drug approved recently by the U.S. FDA. This approach requires an aggressive chemical and analytical search for potential impurities in the starting materials, intermediates and drug substance, and experimental studies to track their fate through the manufacturing process in order to understand the process capability for rejecting such impurities. Comprehensive IFM can provide elements of control strategies for impurities. This paper highlights the critical roles that analytical sciences play in the IFM process and impurity control. The application of various analytical techniques (HPLC, LC-MS, NMR, etc.) and development of sensitive and selective methods for impurity detection, identification, separation and quantification are highlighted with illustrative examples. As an essential part of the entire control strategy for Pazopanib hydrochloride, analytical control of impurities with 'meaningful' specifications and the 'right' analytical methods is addressed. In particular, IFM provides scientific justification that can allow for control of process impurities up-stream at the starting materials or intermediates whenever possible.

  2. A validated stability-indicating ultra performance liquid chromatography method for the determination of potential process-related impurities in eplerenone.

    PubMed

    Du, Mingluo; Pan, Chunyan; Chen, Jing; Song, Min; Zhu, Tingting; Hang, Taijun

    2016-08-01

    A simple, sensitive, and accurate stability-indicating analytical method has been developed and validated using ultra high performance liquid chromatography. The developed method is used to evaluate the related substances of eplerenone (EP). The degradation behavior of EP under stress conditions was determined, and the major degradants were identified by ultra high performance liquid chromatography with tandem mass spectrometry. The chromatographic conditions were optimized using an impurity-spiked solution, and the samples, generated from forced degradation studies. The resolution of EP, its potential impurities, and its degradation products was performed on a Waters UPLC BEH C18 column (50 × 2.1 mm, 1.7 μm) by linear gradient elution using a mobile phase consisting of 10 mmol/L ammonium acetate adjusted to pH 4.5, methanol and acetonitrile. A photo-diode array detector set at 245 nm was used for detection. The flow rate was set at 0.3 mL/min. The procedure had good specificity, linearity (0.02-3.14 μg/mL), recovery (96.1-103.9%), limit of detection (0.01-0.02 μg/mL), limit of quantitation (0.03-0.05 μg/mL), and robustness. The correction factors of the process-related substances were calculated.

  3. Process and system for removing impurities from a gas

    DOEpatents

    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.

  4. Metal impurities provide useful tracers for identifying exposures to airborne single-wall carbon nanotubes released from work-related processes

    NASA Astrophysics Data System (ADS)

    Rasmussen, Pat E.; Jayawardene, Innocent; Gardner, H. David; Chénier, Marc; Levesque, Christine; Niu, Jianjun

    2013-04-01

    This study investigated the use of metal impurities in single-wall carbon nanotubes (SWCNT) as potential tracers to distinguish engineered nanomaterials from background aerosols. TEM and SEM were used to characterize parent material and aerosolized agglomerates collected on PTFE filters using a cascade impactor. SEM image analysis indicated that the SWCNT agglomerates contained about 45% amorphous carbon and backscatter electron analysis indicated that metal impurities were concentrated within the amorphous carbon component. Two elements present as impurities (Y and Ni) were selected as appropriate tracers in this case as their concentrations were found to be highly elevated in the SWCNT parent material (% range) compared to ambient air particles (μg/g range), and background air concentrations were below detection limits for both elements. Bioaccessibility was also determined using physiologically-based extractions at pH conditions relevant to both ingestion and inhalation pathways. A portable wet electrostatic precipitation system effectively captured airborne Y and Ni released during sieving processes, in proportions similar to the bulk sample. These observations support the potential for catalysts and other metal impurities in carbon nanotubes to serve as tracers that uniquely identify emissions at source, after an initial analysis to select appropriate tracers.

  5. Hybrid functional calculations of Copper impurities and related complexes in Silicon

    NASA Astrophysics Data System (ADS)

    Sharan, Abhishek; Gui, Zhigang; Janotti, Anderson

    Copper impurities affect electronic and optical properties of semiconductors. Cu is an ubiquitous impurity and can be introduced unintentionally during various processing step. In silicon, the fast-diffusing interstitial Cu donor often passivates shallow-acceptor dopants, affecting the electronic characteristics of devices, while deep levels associated with other forms of the Cu impurity degrade device performance. Here we revisit the problem of the Cu impurity in Si using first principles calculation based on a hybrid functional. We discuss the relative stability of the substitutional and interstitial forms, as well as the formation of complexes with hydrogen and oxygen impurities. The results of our calculations will be compared with recent experiments on the electrical activity of Cu impurities in Si.

  6. Extraction process for removing metallic impurities from alkalide metals

    SciTech Connect

    Royer, Lamar T.

    1988-01-01

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

  7. Extraction process for removing metallic impurities from alkalide metals

    SciTech Connect

    Royer, L.T.

    1987-03-20

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

  8. Process for the removal of impurities from combustion fullerenes

    DOEpatents

    Alford, J. Michael; Bolskar, Robert

    2005-08-02

    The invention generally relates to purification of carbon nanomaterials, particularly fullerenes, by removal of PAHs and other hydrocarbon impurities. The inventive process involves extracting a sample containing carbon nanomaterials with a solvent in which the PAHs are substantially soluble but in which the carbon nanomaterials are not substantially soluble. The sample can be repeatedly or continuously extracted with one or more solvents to remove a greater amount of impurities. Preferred solvents include ethanol, diethyl ether, and acetone. The invention also provides a process for efficiently separating solvent extractable fullerenes from samples containing fullerenes and PAHs wherein the sample is extracted with a solvent in which both fullerenes and PAHs are substantially soluble and the sample extract then undergoes selective extraction to remove PAHs. Suitable solvents in which both fullerenes and PAHs are soluble include o-xylene, toluene, and o-dichlorobenzene. The purification process is capable of treating quantities of combustion soot in excess of one kilogram and can produce fullerenes or fullerenic soot of suitable purity for many applications.

  9. 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.

  10. PROCESS FOR RECOVERY OF URANIUM VALUES FROM IMPURE SOLUTIONS THEREOF

    DOEpatents

    Kilner, S.B.

    1959-11-01

    A process is presented for the recovery of uraninm values from impure solutions which are obtained, for example, by washing residual uranium salt or uranium metal deposits from stainless steel surfaces using an aqueous or certain acidic aqueous solutions. The solutions include uranyl and oxidized iron, chromium, nickel, and copper ions and may contain manganese, zinc, and silver ions. In accordance with one procedure. the uranyl ions are reduced to the uranous state, and the impurity ions are complexed with cyanide under acidic conditions. The solution is then treated with ammonium hydroxide or alkali metal hydroxide to precipitate uranous hydroxide away from the complexed impurity ions in the solution. Alternatively, an excess of alkali metal cyanide is added to the reduced solution until the solution becomes sufficiently alkaline for the uranons hydroxide to precipitate. An essential feature in operating the process is in maintaining the pH of the solution sufficiently acid during the complexing operation to prevent the precipitation of the impurity metal hydroxides.

  11. Impurity trapped exciton states related to rare earth ions in crystals under high hydrostatic pressure

    SciTech Connect

    Grinberg, M. Mahlik, S.

    2013-01-15

    Emission related to rare earth ions in solids takes place usually due to 4f{sup n} {yields} 4f{sup n} and 4f{sup n-1}5d{sup 1} {yields} 4f{sup n} internal transitions. In the case of band to band excitation the effective energy transfer from the host to optically active impurity is required. Among other processes one of the possibilities is capturing of the electron at excited state and hole at the ground state of impurity. Localization of electron or hole at the dopand site creates a long range Coulomb potential that attracts the second carrier which then occupies the localized Rydberg-like states. Such a system can be considered as impurity trapped exciton. Usually impurity trapped exciton is a short living phenomenon which decays non-radiatively leaving the impurity ion in the excited state. However, in several compounds doped with Eu{sup 2+} the impurity trapped exciton states become stable and contribute to the radiative processes though anomalous luminescence that appears apart of the 4f{sup 7} {yields} 4f{sup 7} and 4f{sup 7}5d{sup 1} {yields} 5f{sup 7} emission. In this contribution pressure effect on energies of the 4f{sup n-1}5d{sup 1}{yields}5f{sup n} transitions in Ln doped oxides and fluorides as well as influence of pressure on the energy of impurity trapped exciton states is discussed. The latest results on high pressure investigations of luminescence related to Pr{sup 3+}, and Eu{sup 2+} in different lattices are reviewed.

  12. Development and validation of a stability-indicating RP-HPLC method for the simultaneous estimation of process related impurities and degradation products of rasagiline mesylate in pharmaceutical formulation.

    PubMed

    Reddy, P Sunil; Sudhakar Babu, K; Kumar, Navneet

    2013-03-01

    A sensitive, stability-indicating gradient reverse phase high-performance liquid chromatography-ultraviolet method has been developed for the quantitative determination of process-related impurities and forced degradation products of rasagiline mesylate in pharmaceutical formulation. Efficient chromatographic separation was achieved on an ACE C8, 150 × 4.6 mm, 3 µm column with mobile phase containing a gradient mixture of solvents A and B. The flow rate of the mobile phase was 0.8 mL/min with column temperature of 30°C and detection wavelength at 210 nm. Rasagiline was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Rasagiline was found to degrade significantly in acid and thermal stress conditions. The degradation products were well resolved from rasagiline and its impurities. The peak purity test results confirmed that the rasagiline peak was homogenous and pure in all stress samples and the mass balance was found to be more than 97%, thus proving the stability-indicating power of the method. The developed method was validated according to the guidelines of the International Conference on Harmonization with respect to specificity, linearity, limits of detection and quantification, accuracy, precision and robustness.

  13. Effects of Impurities and Processing on Silicon Solar Cells, Phase 3

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    Results of the 14th quarterly report are presented for a program designed to assess the effects of impurities, thermochemical processes and any impurity process interactions on the performance of terrestrial silicon solar cells. The Phase 3 effort encompasses: (1) potential interactions between impurities and thermochemical processing of silicon; (2) impurity-cell performance relationships in n-base silicon; (3) effect of contaminants introduced during silicon production, refining or crystal growth on cell performance; (4) effects of nonuniform impurity distributions in large area silicon wafers; and (5) a preliminary study of the permanence of impurity effects in silicon solar cells.

  14. Oxygen and carbon impurities and related defects in silicon

    NASA Technical Reports Server (NTRS)

    Pearce, C. W.

    1985-01-01

    Oxygen and carbon are the predominant impurities in Czochralski-grown silicon. The incorporation of oxygen and carbon during crystal growth is reviewed and device effects are discussed. Methods for controlling oxygen and carbon incorporation during crystal growth are discussed and results supporting a segregation coefficient of k=0.5 for oxygen are presented. The nucleation and precipitation behavior of oxygen is complex. Temperature and doping level effects which add insight into the role of point defects in the nucleation process are highlighted. In general, precipitation is found to be retarded in N+ and P+ silicon. The types and quantities of defects resulting from the oxygen precipitates is of interest as they are technologically useful in the process called intrinsic gettering. A comparison is made between the available defect sites and the quantities of metallic impurities present in a typical wafer which need to be gettered. Finally, a discussion of the denuded-zone, intrinsic-gettered (DZ-IG) structure on device properties is presented.

  15. The Effect of Impurities on the Processing of Aluminum Alloys

    SciTech Connect

    Zi-Kui Liu; Shengjun Zhang; Qingyou Han; Vinod Sikka

    2007-04-23

    For this Aluminum Industry of the Future (IOF) project, the effect of impurities on the processing of aluminum alloys was systematically investigated. The work was carried out as a collaborative effort between the Pennsylvania State University and Oak Ridge National Laboratory. Industrial support was provided by ALCOA and ThermoCalc, Inc. The achievements described below were made. A method that combines first-principles calculation and calculation of phase diagrams (CALPHAD) was used to develop the multicomponent database Al-Ca-K-Li-Mg-Na. This method was extensively used in this project for the development of a thermodynamic database. The first-principles approach provided some thermodynamic property data that are not available in the open literature. These calculated results were used in the thermodynamic modeling as experimental data. Some of the thermodynamic property data are difficult, if not impossible, to measure. The method developed and used in this project allows the estimation of these data for thermodynamic database development. The multicomponent database Al-Ca-K-Li-Mg-Na was developed. Elements such as Ca, Li, Na, and K are impurities that strongly affect the formability and corrosion behavior of aluminum alloys. However, these impurity elements are not included in the commercial aluminum alloy database. The process of thermodynamic modeling began from Al-Na, Ca-Li, Li-Na, K-Na, and Li-K sub-binary systems. Then ternary and higher systems were extrapolated because of the lack of experimental information. Databases for five binary alloy systems and two ternary systems were developed. Along with other existing binary and ternary databases, the full database of the multicomponent Al-Ca-K-Li-Mg-Na system was completed in this project. The methodology in integrating with commercial or other aluminum alloy databases can be developed. The mechanism of sodium-induced high-temperature embrittlement (HTE) of Al-Mg is now understood. Using the thermodynamic

  16. Development and validation of a stability indicating assay of doxofylline by RP-HPLC: ESI-MS/MS, ¹H and ¹³C NMR spectroscopic characterization of degradation products and process related impurities.

    PubMed

    Rao, R Nageswara; Naidu, Ch Gangu; Prasad, K Guru; Santhakumar, B; Saida, Shaik

    2013-05-01

    A validated stability indicating RP-HPLC assay of doxofylline was developed by separating its related substances and degradants on LichrocartC18 (250 mm × 4.6 mm; 5 μm) column using 10 mM ammonium acetate and acetonitrile as a mobile phase in a gradient mode of elution at a flow rate of 1.0 mL/min at 30 °C. The column effluents were monitored by a photo diode array detector set at 274 nm. The method was validated in terms of accuracy, precision and linearity as per ICH guidelines. The limits of quantification of doxofylline and impurities were obtained in the range of 0.19-0.36 μg/mL. Forced degradation of doxofylline was carried out under acidic, basic, thermal, photo, peroxide conditions and the degradation products were isolated and characterized by ESI-MS/MS, (1)H and (13)C spectroscopy. The method was successfully applied not only to quantify related substances and degradation products but also assay of doxofylline in bulk drugs. The recoveries of doxofylline and impurities were in the range of 99.00-100.05% and 97.83-99.86% respectively.

  17. Relationships among impurity components, sucrose, and sugarbeet processing quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sodium, potassium, amino-nitrogen, and invert sugar are naturally-occurring constituents of the sugarbeet (Beta vulgaris L.) root, referred to as impurities, which impede sucrose extraction during routine factory operations. Three germplasm lines selected for low sodium, potassium, or amino-nitrogen...

  18. 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.

  19. NMR and mass spectrometric characterization of vinblastine, vincristine and some new related impurities - part I.

    PubMed

    Dubrovay, Zsófia; Háda, Viktor; Béni, Zoltán; Szántay, Csaba

    2013-10-01

    In the course of exploring the possibilities of developing a new, improved process at Gedeon Richter for the production of the "bisindole" alkaloids vinblastine (VLB) and vincristine (VCR), some novel VLB/VCR-related trace impurities were detected by analytical HPLC. Following isolation by preparative HPLC, a combination of 1D and 2D ultra high-field NMR and high-resolution (HR) (LC-)MS/MS studies allowed the structural identification and complete spectral characterization of several hitherto unpublished VLB/VCR-analogue impurities. Since the impurities could not be isolated in entirely pure forms and were available only in minute, mass-limited quantities, accessing the spectral information needed for their ab initio structure determination was met with various practical difficulties. Successful structure determination therefore relied heavily on the availability and use of detailed and definitive spectral data for both VLB and VCR. In particular, the utilization of detailed (1)H, (13)C, and (15)N NMR assignments as well as (1)H-(1)H, (1)H-(13)C and (1)H-(15)N spin-spin connectivities pertaining to different solvents for VLB/VCR base and sulphate salt was required. Although NMR studies on VLB base and other bisindoles were reported earlier in the literature, an NMR characterization of VLB and VCR under the above-mentioned circumstances and using ultra-high field instrumentation is either scarcely available or entirely lacking, therefore the necessary data had to be obtained in-house. Likewise, a modern tandem HR-ESI-MS/MS(n) fragmentation study of VLB and VCR has not been published yet. In the present paper we therefore give a thorough NMR and MS characterization of VLB and VCR specifically with a view to filling this void and to provide sufficiently extensive and solid reference data for the structural investigation of the aforementioned VLB/VCR impurities. Besides being scientifically relevant in its own right, the disclosed data should be useful for anyone

  20. 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.

  1. Stability-indicating LC method for the estimation of bendamustine hydrochloride and its related impurities.

    PubMed

    Kasa, Srinivasulu; Raja Sekhar Reddy, M; Kadaboina, Raja Sekhar; Murki, Veerender; Mulukutla, Venkata Suryanarayana

    2014-08-01

    A novel, simple, sensitive and stability-indicating high-performance liquid chromatography method was developed and validated for the quantification of impurities (process related and degradants) and the assay determination of Bendamustine hydrochloride. A chromatographic separation of Bendamustine and its impurities was achieved with an Inertsil ODS-2 analytical column, 250 × 4.6 mm, 5 µm, using gradient elution with mobile phase A consisting of a mixture of water and trifluoroacetic acid (1000:1, v/v) and mobile phase B consisting of acetonitrile. The instrumental settings included a flow rate of 1.0 mL/min, column temperature of 27°C and a detector wavelength of 233 nm, using a photodiode array detector. The tailing factor for Bendamustine was 1.10. Bendamustine hydrochloride was exposed to thermal, photolytic, hydrolytic and oxidative stress conditions and the stressed samples were analyzed by the proposed method. Peak homogeneity data of Bendamustine were obtained by using a photodiode array detector in the stressed sample chromatograms, which demonstrated the specificity of the method for estimation in the presence of degradants. The developed method was validated for parameters such as precision, accuracy, linearity, limit of detection, limit of quantification, ruggedness and robustness. The stability tests were also performed on drug substances as per International Conference on Harmonization guidelines. PMID:23825351

  2. Role of impurity molecules in radiation-initiated processes in solid carbohydrates

    SciTech Connect

    Kavetskii, V.G.; Yudin, I.V.

    1992-09-01

    Extension of the use of ionizing radiation for sterilization of medicinal preparations is stimulating the study of radiation-initiated processes in solid polyhydroxyl matrixes containing impurities of various organic substances. Such investigations make it possible to establish common characteristics of the effect of impurity molecules on the radiolysis of organic crystals. The materials of the investigation were lactose and rhamnose, precipitated by slow evaporation of the solvent from saturated aqueous solutions with different dihydroxyacetone contents. 4 refs., 1 fig.

  3. Identification of process related trace level impurities in the actinide decorporation agent 3,4,3-LI(1,2-HOPO): Nozzle–skimmer fragmentation via ESI LC–QTOFMS

    DOE PAGES

    Panyala, Nagender R.; Sturzbecher-Hoehne, Manuel; Abergel, Rebecca J.

    2014-08-12

    We report that 3,4,3-LI(1,2-HOPO) is a chelating ligand and decorporation agent that can remove radioactive lanthanides and actinides from the body. Identification of trace impurities in drug samples is gaining much interest due to their significant influence on drug activity. In this study, trace impurities were detected in manufactured lots of 3,4,3-LI(1,2-HOPO) by a developed method of Liquid Chromatography coupled with photo-diode array UV detection and Electrospray Ionization-Quadrupole Time of Flight Mass spectrometry (LC-QTOFMS), via induced-in-source or collision-induced mass fragmentation (Nozzle-Skimmer Fragmentation). Molecular ions were fragmented within the nozzle-skimmer region of electrospray ionization (ESI) mass spectrometer equipped with a Timemore » of Flight detector. Eight major (detected at levels higher than a 0.1% threshold) and seven minor trace impurities were identified. The respective structures of these impurities were elucidated via analysis of the generated fragment ions using mass fragmentation and elemental composition software. Proposed structures of impurities were further confirmed via isotopic modeling.« less

  4. Identification of process related trace level impurities in the actinide decorporation agent 3,4,3-LI(1,2-HOPO): Nozzle-skimmer fragmentation via ESI LC-QTOFMS.

    PubMed

    Panyala, Nagender R; Sturzbecher-Hoehne, Manuel; Abergel, Rebecca J

    2014-11-01

    3,4,3-LI(1,2-HOPO) is a chelating ligand and decorporation agent that can remove radioactive lanthanides and actinides from the body. Identification of trace impurities in drug samples is gaining much interest due to their significant influence on drug activity. In this study, trace impurities were detected in manufactured lots of 3,4,3-LI(1,2-HOPO) by a developed method of liquid chromatography coupled with photo-diode array UV detection and electrospray ionization-quadrupole time of flight mass spectrometry (LC-QTOFMS), via induced-in-source or collision-induced mass fragmentation (nozzle-skimmer fragmentation). Molecular ions were fragmented within the nozzle-skimmer region of electrospray ionization (ESI) mass spectrometer equipped with a Time of Flight detector. Eight major (detected at levels higher than a 0.1% threshold) and seven minor trace impurities were identified. The respective structures of these impurities were elucidated via analysis of the generated fragment ions using mass fragmentation and elemental composition software. Proposed structures of impurities were further confirmed via isotopic modeling.

  5. Identification of process related trace level impurities in the actinide decorporation agent 3,4,3-LI(1,2-HOPO): Nozzle–skimmer fragmentation via ESI LC–QTOFMS

    SciTech Connect

    Panyala, Nagender R.; Sturzbecher-Hoehne, Manuel; Abergel, Rebecca J.

    2014-08-12

    We report that 3,4,3-LI(1,2-HOPO) is a chelating ligand and decorporation agent that can remove radioactive lanthanides and actinides from the body. Identification of trace impurities in drug samples is gaining much interest due to their significant influence on drug activity. In this study, trace impurities were detected in manufactured lots of 3,4,3-LI(1,2-HOPO) by a developed method of Liquid Chromatography coupled with photo-diode array UV detection and Electrospray Ionization-Quadrupole Time of Flight Mass spectrometry (LC-QTOFMS), via induced-in-source or collision-induced mass fragmentation (Nozzle-Skimmer Fragmentation). Molecular ions were fragmented within the nozzle-skimmer region of electrospray ionization (ESI) mass spectrometer equipped with a Time of Flight detector. Eight major (detected at levels higher than a 0.1% threshold) and seven minor trace impurities were identified. The respective structures of these impurities were elucidated via analysis of the generated fragment ions using mass fragmentation and elemental composition software. Proposed structures of impurities were further confirmed via isotopic modeling.

  6. Identification of process related trace level impurities in the actinide decorpration agent 3,4,3-LI(1,2-HOPO): Nozzle-Skimmer fragmentation via ESI LC-QTOFMS

    PubMed Central

    Panyala, Nagender R.; Sturzbecher-Hoehne, Manuel; Abergel, Rebecca J.

    2014-01-01

    3,4,3-LI(1,2-HOPO) is a chelating ligand and decorporation agent that can remove radioactive lanthanides and actinides from the body. Identification of trace impurities in drug samples is gaining much interest due to their significant influence on drug activity. In this study, trace impurities were detected in manufactured lots of 3,4,3-LI(1,2-HOPO) by a developed method of Liquid Chromatography coupled with photo-diode array UV detection and Electrospray Ionization-Quadrupole Time of Flight Mass spectrometry (LC-QTOFMS), via induced-in-source or collision-induced mass fragmentation (Nozzle-Skimmer Fragmentation). Molecular ions were fragmented within the nozzle-skimmer region of electrospray ionization (ESI) mass spectrometer equipped with a Time of Flight detector. Eight major (detected at levels higher than a 0.1% threshold) and seven minor trace impurities were identified. The respective structures of these impurities were elucidated via analysis of the generated fragment ions using mass fragmentation and elemental composition software. Proposed structures of impurities were further confirmed via isotopic modeling. PMID:25165012

  7. Fused salt processing of impure plutonium dioxide to high-purity plutonium metal

    SciTech Connect

    Mullins, L.J.; Christensen, D.C.; Babcock, B.R.

    1982-01-01

    A process for converting impure plutonium dioxide (approx. 96% pure) to high-purity plutonium metal (>99.9%) was developed. The process consists of reducing the oxide to an impure plutonium metal intermediate with calcium metal in molten calcium chloride. The impure intermediate metal is cast into an anode and electrorefined to produce high-purity plutonium metal. The oxide reduction step is being done now on a 0.6-kg scale with the resulting yield being >99.5%. The electrorefining is being done on a 4.0-kg scale with the resulting yield being 80 to 85%. The purity of the product, which averages 99.98%, is essentially insensitive to the purity of the feed metal. The yield, however, is directly dependent on the chemical composition of the feed. To date, approximately 250 kg of impure oxide has been converted to pure metal by this processing sequence. The availability of impure plutonium dioxide, together with the need for pure plutonium metal, makes this sequence a valuable plutonium processing tool.

  8. Towards quantum information processing with impurity spins insilicon

    SciTech Connect

    Schenkel, T.; Liddle, J.A.; Bokor, J.; Rangelow, I.W.; Park,S.J.; Persaud, A.

    2004-03-01

    The finding of algorithms for factoring and data base search that promise substantially increased computational power, as well as the expectation for efficient simulation of quantum systems have spawned an intense interest in the realization of quantum information processors [1]. Solid state implementations of quantum computers scaled to >1000 quantum bits ('qubits') promise to revolutionize information technology, but requirements with regard to sources of decoherence in solid state environments are sobering. Here, we briefly review basic approaches to impurity spin based qubits and present progress in our effort to form prototype qubit test structures. Since Kane's bold silicon based spin qubit proposal was first published in 1998 [2], several groups have taken up the challenge of fabricating elementary building blocks [3-5], and several exciting variations of single donor qubit schemes have emerged [6]. Single donor atoms, e. g. {sup 31}P, are 'natural quantum dots' in a silicon matrix, and the spins of electrons and nuclei of individual donor atoms are attractive two level systems for encoding of quantum information. The coupling to the solid state environment is weak, so that decoherence times are long (hours for nuclear spins, and {approx}60 ms for electron spins of isolated P atoms in silicon [7]), while control over individual spins for one qubit operations becomes possible when individual qubits are aligned to electrodes that allow shifting of electron spin resonances in global magnetic fields by application of control voltages. Two qubit operations require an interaction that couples, and entangles qubits. The exchange interaction, J, is a prime candidate for mediation of two qubit operations, since it can be turned on and off by variation of the wave function overlap between neighboring qubits, and coherent manipulation of quantum information with the exchange interaction alone has been shown to be universal [8]. However, detailed band structure

  9. Influence of radiative processes on the ignition of deuterium-tritium plasma containing inactive impurities

    NASA Astrophysics Data System (ADS)

    Gus'kov, S. Yu.; Sherman, V. E.

    2016-08-01

    The degree of influence of radiative processes on the ignition of deuterium-tritium (DT) plasma has been theoretically studied as dependent on the content of inactive impurities in plasma. The analytic criterion of plasma ignition in inertial confinement fusion (ICF) targets is modified taking into account the absorption of intrinsic radiation from plasma in the ignition region. The influence of radiative processes on the DT plasma ignition has been analytically and numerically studied for plasma that contains a significant fraction of inactive impurities either as a result of DT fuel mixing with ICF target ablator material or as a result of using light metal DT-hydrides as solid noncryogenic fuel. It has been shown that the effect of the absorption of intrinsic radiation leads to lower impurity-induced increase in the ignition energy as compared to that calculated in the approximation of optically transparent ignition region.

  10. Process for purifying and cooling partial oxidation gases containing dust-like impurities

    SciTech Connect

    Geidies, U.; Wilmer, G.

    1982-05-04

    The hot partial oxidation gases which are formed in a gasifier for solid or liquid fuel are passed first into a dust separator under conditions where 70 to 95% of the impurities are eliminated , whereupon the gases then are washed in a wet washer with an amount of water not higher than necessary to remove the residual dust impurities. The process has the particular advantage of a very low amount of drainage water and has a high safety factor and adaptability for different conditions.

  11. Evaluation of helium impurity impacts on Spent Nuclear Fuel project processes (OCRWM)

    SciTech Connect

    SHERRELL, D.L.

    1999-09-21

    This document identifies the types and quantities of impurities that may be present within helium that is introduced into multi-canister overpacks (MCO)s by various SNF Project facilities, including, but not limited to the Cold Vacuum Drying (CVD) Facility (CVDF). It then evaluates possible impacts of worst case impurity inventories on MCO drying, transportation, and storage processes. Based on the evaluation results, this document: (1) concludes that the SNF Project helium procurement specification can be a factor-of-ten less restrictive than a typical vendor's standard offering (99.96% pure versus the vendor's 99.997% pure standard offering); (2) concludes that the CVDF's current 99.5% purity requirement is adequate to control the quality of the helium that is delivered to the MCO by the plant's helium distribution system; and (3) recommends specific impurity limits for both of the above cases.

  12. JET Carbon Screening Experiments Using Methane Gas Puffing and its Relation to Intrinsic Carbon Impurities

    NASA Astrophysics Data System (ADS)

    Strachan, Jim

    2002-11-01

    Impurity depletion results from three impurity processes: 1) generation at the plasma facing materials, 2) penetration through the SOL to the core, and 3) confinement in the plasma core. Carbon screening experiments using methane gas injection [1] quantify the second process, and elucidate some features of the first process. JET L-Mode experiments scanned those parameters influencing the JET SOL and/or intrinsic impurity level. An empirical scaling was derived for carbon penetration into L-Mode JET plasmas. L-Mode screening was 3-20 times better for plasmas connected to the divertor than for similar limited plasmas. The screening was worse for methane injection from the mid-plane and best for injection from the divertor. The screening was worse for H-Mode than L-Mode. Both ELM-averaged and inter-ELM H-Mode screening was documented. The screening results were used to understand the intrinsic impurity levels which decreased at higher density partly due to better carbon screening. Diverted L-Mode intrinsic carbon arose from both the main chamber and the divertor. At higher power, and therefore in H-Mode, the carbon originated primarily from the divertor. DIVIMP and EDGE2D were used to model the observed screening. The modelling indicated carbon removal to the divertor required lower SOL temperatures in order for Coulomb collisions to couple the impurity ions to the deuterium SOL flows. Consequently, carbon removal occurred primarily in the outer SOL regions. [1]G.M. McCracken, et al, Nuclear Fusion 33, 1409 (1993)

  13. Silicon materials task of the Low Cost Solar Array Project: Effect of impurities and processing on silicon solar cells

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.; Davis, J. R.; Rohatgi, A.; Hanes, M. H.; Rai-Choudhury, P.; Mollenkopf, H. C.

    1982-01-01

    The effects of impurities and processing on the characteristics of silicon and terrestrial silicon solar cells were defined in order to develop cost benefit relationships for the use of cheaper, less pure solar grades of silicon. The amount of concentrations of commonly encountered impurities that can be tolerated in typical p or n base solar cells was established, then a preliminary analytical model from which the cell performance could be projected depending on the kinds and amounts of contaminants in the silicon base material was developed. The impurity data base was expanded to include construction materials, and the impurity performace model was refined to account for additional effects such as base resistivity, grain boundary interactions, thermal processing, synergic behavior, and nonuniform impurity distributions. A preliminary assessment of long term (aging) behavior of impurities was also undertaken.

  14. Sixth workshop on the role of impurities and defects in silicon device processing

    SciTech Connect

    Tan, T.; Swanson, R.; Sopori, B.

    1996-09-01

    The Sixth Workshop on the Role of Impurities and Defects in Silicon Device Processing was held in Snowmass Village, August 12-14, 1996. The workshop was attended by 87 participants from academic institutions and photovoltaic industry representatives, from the United States, Australia, Belgium, Canada, France, Germany, Italy, Japan, Belgium, and The Netherlands. The workshop consisted of nine sessions that addressed different aspects of impurities and defects in silicon and applications to solar-cell processing. Each session opened with some review talks summarizing recent advances in this field and introduced important issues for further discussions during a subsequent panel discussion session. In addition, the latest research results were presented in two poster sessions.

  15. Thermionic performance of a cesium diminiode with relatively impure 110-tungsten electrodes

    NASA Technical Reports Server (NTRS)

    Smith, A. L.; Manista, E. J.; Morris, J. F.

    1974-01-01

    Thermionic performance data from a miniature plane cesium diode (diminiode) with 110-tungsten electrodes are presented. The diminiode has a guard-ringed collector and a spacing of 0.23 mm. The data were obtained by using a computerized acquisition system. The diode was tested at increments between 1700 and 1900 K for the emitter, 694 and 1101 K for the collector, and 519 and 650 K for the reservoir. A maximum power density of 4.5 W/sq cm was obtained at an emitter temperature of 1900 K. This relatively low output probably results from high carbon and sodium impurities in the electrode materials.

  16. Effects of the impurity-host interactions on the nonradiative processes in ZnS:Cr

    NASA Astrophysics Data System (ADS)

    Tablero, C.

    2010-11-01

    There is a great deal of controversy about whether the behavior of an intermediate band in the gap of semiconductors is similar or not to the deep-gap levels. It can have significant consequences, for example, on the nonradiative recombination. In order to analyze the behavior of an intermediate band, we have considered the effect of the inward and outward displacements corresponding to breathing and longitudinal modes of Cr-doped ZnS and on the charge density for different processes involved in the nonradiative recombination using first-principles. This metal-doped zinc chalcogenide has a partially filled band within the host semiconductor gap. In contrast to the properties exhibited by deep-gap levels in other systems, we find small variations in the equilibrium configurations, forces, and electronic density around the Cr when the nonradiative recombination mechanisms modify the intermediate band charge. The charge density around the impurity is equilibrated in response to the perturbations in the equilibrium nuclear configuration and the charge of the intermediate band. The equilibration follows a Le Chatelier principle through the modification of the contribution from the impurity to the intermediate band and to the valence band. The intermediate band introduced by Cr in ZnS for the concentrations analyzed makes the electronic capture difficult and later multiphonon emission in the charge-transfer processes, in accordance with experimental results.

  17. Chromatographic resolution of closely related species in pharmaceutical chemistry: dehalogenation impurities and mixtures of halogen isomers.

    PubMed

    Regalado, Erik L; Zhuang, Ping; Chen, Yadan; Makarov, Alexey A; Schafer, Wes A; McGachy, Neil; Welch, Christopher J

    2014-01-01

    In recent years, the use of halogen-containing molecules has proliferated in the pharmaceutical industry, where the incorporation of halogens, especially fluorine, has become vitally important for blocking metabolism and enhancing the biological activity of pharmaceuticals. The chromatographic separation of halogen-containing pharmaceuticals from associated isomers or dehalogenation impurities can sometimes be quite difficult. In an attempt to identify the best current tools available for addressing this important problem, a survey of the suitability of four chromatographic method development platforms (ultra high-performance liquid chromatography (UHPLC), core shell HPLC, achiral supercritical fluid chromatography (SFC) and chiral SFC) for separating closely related mixtures of halogen-containing pharmaceuticals and their dehalogenated isosteres is described. Of the 132 column and mobile phase combinations examined for each mixture, a small subset of conditions were found to afford the best overall performance, with a single UHPLC method (2.1 × 50 mm, 1.9 μm Hypersil Gold PFP, acetonitrile/methanol based aqueous eluents containing either phosphoric or perchloric acid with 150 mM sodium perchlorate) affording excellent separation for all samples. Similarly, a survey of several families of closely related halogen-containing small molecules representing the diversity of impurities that can sometimes be found in purchased starting materials for synthesis revealed chiral SFC (Chiralcel OJ-3 and Chiralpak IB, isopropanol or ethanol with 25 mM isobutylamine/carbon dioxide) as well as the UHPLC (2.1 × 50 mm, 1.8 μm ZORBAX RRHD Eclipse Plus C18 and the Gold PFP, acetonitrile/methanol based aqueous eluents containing phosphoric acid) as preferred methods.

  18. Performance of a palladium membrane reactor using a Ni catalyst for fusion fuel impurities processing

    SciTech Connect

    Willms, R.S.; Wilhelm, R.; Okuno, K.

    1994-07-01

    The palladium membrane reactor (PNM) provides a means to recover hydrogen isotopes from impurities expected to be present in fusion reactor exhaust. This recovery is based on reactions such as water-gas shift and steam reforming for which conversion is equilibrium limited. By including a selectively permeable membrane such as Pd/Ag in the catalyst bed, hydrogen isotopes can be removed from the reacting environment, thus promoting the reaction to complete conversion. Such a device has been built and operated at the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory (LANL). For the reactions listed above, earlier study with this unit has shown that hydrogen single-pass recoveries approaching 100% can be achieved. It was also determined that a nickel catalyst is a feasible choice for use with a PMR appropriate for fusion fuel impurities processing. The purpose of this study was to systematically assess the performance of the PMR using a nickel catalyst over a range of temperatures, feed compositions and flowrates. Reactions which were studied are the water-gas shift reaction and steam reforming.

  19. Few-boson processes in the presence of an attractive impurity under one-dimensional confinement

    NASA Astrophysics Data System (ADS)

    Mehta, Nirav; Morehead, Connor

    2016-05-01

    We consider the universal few-body physics of a single light impurity atom (L) interacting with a few heavier atoms (H) under strict one-dimensional confinement with zero-range interactions. Due to the mass imbalance, the system is non-integrable. All universal properties are specified by the mass ratio β =mL /mH and the coupling ratio λ =gHH /gHL , enabling the calculation of few-body ``phase diagrams'' on the λ- β plane. Because the three-body and four-body eigenenergies determine the energy thresholds for inelastic scattering processes involving HL , HHL and HHHL collision partners, we are able to partition the λ- β phase space into regions according to whether or not particular inelastic processes are energetically allowed.

  20. Relational Processing Following Stroke

    ERIC Educational Resources Information Center

    Andrews, Glenda; Halford, Graeme S.; Shum, David; Maujean, Annick; Chappell, Mark; Birney, Damian

    2013-01-01

    The research examined relational processing following stroke. Stroke patients (14 with frontal, 30 with non-frontal lesions) and 41 matched controls completed four relational processing tasks: sentence comprehension, Latin square matrix completion, modified Dimensional Change Card Sorting, and n-back. Each task included items at two or three…

  1. Silicon materials task of the low-cost solar array project. Phase 4: Effects of impurities and processing on silicon solar cells

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.; Hanes, M. H.; Davis, J. R.; Rohatgi, A.; Rai-Choudhury, P.; Mollenkopf, H. C.

    1981-01-01

    The effects of impurities, various thermochemical processes, and any impurity-process interactions upon the performance of terrestrial solar cells are defined. The results form a basis for silicon producers, wafer manufacturers, and cell fabricators to develop appropriate cost benefit relationships for the use of less pure, less costly solar grade silicon.

  2. 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)

  3. Silicon materials task of the low cost solar array project. Phase 3: Effect of impurities and processing on silicon solar cells

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    The 13th quarterly report of a study entitled an Investigation of the Effects of Impurities and Processing on Silicon Solar Cells is given. The objective of the program is to define the effects of impurities, various thermochemical processes and any impurity-process interactions on the performance of terrestrial silicon solar cells. The Phase 3 program effort falls in five areas: (1) cell processing studies; (2) completion of the data base and impurity-performance modeling for n-base cells; (3) extension of p-base studies to include contaminants likely to be introduced during silicon production, refining or crystal growth; (4) anisotropy effects; and (5) a preliminary study of the permanence of impurity effects in silicon solar cells. The quarterly activities for this report focus on tasks (1), (3) and (4).

  4. Effect of variable valence impurities on the formation of bismuth-related optical centres in a silicate glass

    SciTech Connect

    Galagan, B I; Denker, B I; Lili Hu; Sverchkov, S E; Shulman, I L; Dianov, Evgenii M

    2012-10-31

    We have studied the effect of variable valence impurities (cerium and iron) on the formation of bismuth-related IR luminescence centres and the optical loss between 1000 and 1300 nm in a magnesium aluminosilicate glass. The results demonstrate that additional doping of the glass with ceria leads to effective bleaching in a wide spectral range, including the luminescence range of the bismuth centres. At the same time, ceria reduces the concentration of luminescence centres. Gamma irradiation of the glass bleached by cerium restores the luminescence centres but leads to a background loss in a wide spectral range. Iron is shown to be a very harmful impurity in bismuth-doped active media: even trace levels of iron prevent the formation of bismuth-related active centres in the glass and produce a strong, broad absorption band centred near 1 {mu}m. (luminescence of glasses)

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

    PubMed

    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 -ϵ1(ω)ω(2)); 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

  6. The role of impurities, LIF, and processing on the sintering, microstructure, and optical properties of transparent polycrystalline magnesium aluminate (MgAl2O4) spinel

    NASA Astrophysics Data System (ADS)

    Rubat du Merac, Marc

    shielding. Hot-press experiments with Al2O3, lithium, and fluorine additives, along with thermodynamic simulations and spectrophotometry indicated that aluminum oxy-carbides were likely partly responsible for absorption and that lithium was likely responsible for counteracting absorption. Dilatometry was conducted to study the effect of processing variables, and for the first time of neutron irradiation of starting powders, on the sintering behavior of cold-pressed powder compacts. Green-body density, stoichiometry, and impurities had the greatest effect on densification, whereas powder neutron irradiation and reducing atmosphere had small, but non-negligible effects. Dilatometry in combination with sintering experiments demonstrated that LiF coarsens crystallites by vapor and likely surface transport. Although these mechanisms do not contribute to densification, when combined with high grain-boundary transport and pressure, enhanced densification takes place. Dilatometry also demonstrated that transparent compacts could be fabricated by pressureless sintering. Pressureless field-assisted sintering of spinel was also demonstrated for the first time, producing translucent compacts with fine grain size. Electrochemical impedance spectroscopy, secondary-ion mass spectroscopy, and Raman spectroscopy, in combination with characterization by electron microscopy, were used to relate the dielectric properties of hot-pressed spinel compacts to microstructure. This was the first study to characterize the conductivity of fully-dense, transparent polycrystalline spinel compacts. The higher conductivity of polycrystalline spinel compacts compared to single crystals was attributed to increased conductance from impurities at grain boundaries parallel to the applied field. The lower conductivity of compacts with LiF addition compared to those without LiF addition was attributed to larger grain size and lower impurity content. Compacts with LiF addition exhibited distinct bulk and grain

  7. The role of impurities, LIF, and processing on the sintering, microstructure, and optical properties of transparent polycrystalline magnesium aluminate (MgAl2O4) spinel

    NASA Astrophysics Data System (ADS)

    Rubat du Merac, Marc

    shielding. Hot-press experiments with Al2O3, lithium, and fluorine additives, along with thermodynamic simulations and spectrophotometry indicated that aluminum oxy-carbides were likely partly responsible for absorption and that lithium was likely responsible for counteracting absorption. Dilatometry was conducted to study the effect of processing variables, and for the first time of neutron irradiation of starting powders, on the sintering behavior of cold-pressed powder compacts. Green-body density, stoichiometry, and impurities had the greatest effect on densification, whereas powder neutron irradiation and reducing atmosphere had small, but non-negligible effects. Dilatometry in combination with sintering experiments demonstrated that LiF coarsens crystallites by vapor and likely surface transport. Although these mechanisms do not contribute to densification, when combined with high grain-boundary transport and pressure, enhanced densification takes place. Dilatometry also demonstrated that transparent compacts could be fabricated by pressureless sintering. Pressureless field-assisted sintering of spinel was also demonstrated for the first time, producing translucent compacts with fine grain size. Electrochemical impedance spectroscopy, secondary-ion mass spectroscopy, and Raman spectroscopy, in combination with characterization by electron microscopy, were used to relate the dielectric properties of hot-pressed spinel compacts to microstructure. This was the first study to characterize the conductivity of fully-dense, transparent polycrystalline spinel compacts. The higher conductivity of polycrystalline spinel compacts compared to single crystals was attributed to increased conductance from impurities at grain boundaries parallel to the applied field. The lower conductivity of compacts with LiF addition compared to those without LiF addition was attributed to larger grain size and lower impurity content. Compacts with LiF addition exhibited distinct bulk and grain

  8. Fifth workshop on the role of impurities and defects in silicon device processing. Extended abstracts

    SciTech Connect

    Sopori, B.L.; Luque, A.; Sopori, B.; Swanson, D.; Gee, J.; Kalejs, J.; Jastrzebski, L.; Tan, T.

    1995-08-01

    This workshop dealt with engineering aspects and material properties of silicon electronic devices. Crystalline silicon growth, modeling, and properties are discussed in general and as applied to solar cells. Topics considered in discussions of silicon growth include: casting, string ribbons, Al backside contacts, ion implantation, gettering, passivation, and ultrasound treatments. Properties studies include: Electronic properties of defects and impurities, dopant and carrier concentrations, structure and bonding, nitrogen effects, degradation of bulk diffusion length, and recombination parameters. Individual papers from the workshop are indexed separately on the Energy Data Bases.

  9. Impact of structural defect density on gettering of transition metal impurities during phosphorus emitter diffusion in multi-crystalline silicon solar cell processing

    NASA Astrophysics Data System (ADS)

    Park, Yongkook; Lu, Jinggang; Park, Jin-Hong; Rozgonyi, George

    2015-07-01

    The impact of structural defect density on gettering of transition metal impurities during phosphorous emitter diffusion has been investigated using a pair of multi-crystalline silicon (mc-Si) wafers. Chromium (Cr) impurities incorporated during growth were identified by deep level transient spectroscopy (DLTS) and used to evaluate the gettering efficiency. The Cr impurity concentration in the low defect density region of mc-Si wafers was reduced from ~3.5 × 1013 cm-3 to ~1.7 × 1012 cm-3 after phosphorous diffusion gettering (PDG), while for the high defect density region, there is no appreciable variation in the Cr concentration which only changed from ~3.0 to ~2.2 × 1012 cm-3 following PDG. It was concluded that the gettering process is not effective for highly defective regions of mc-Si wafers due to the ineffective impurity release from structural defects during the PDG process. [Figure not available: see fulltext.

  10. Chemometrics applications in biotechnology processes: predicting column integrity and impurity clearance during reuse of chromatography resin.

    PubMed

    Rathore, Anurag S; Mittal, Shachi; Lute, Scott; Brorson, Kurt

    2012-01-01

    Separation media, in particular chromatography media, is typically one of the major contributors to the cost of goods for production of a biotechnology therapeutic. To be cost-effective, it is industry practice that media be reused over several cycles before being discarded. The traditional approach for estimating the number of cycles a particular media can be reused for involves performing laboratory scale experiments that monitor column performance and carryover. This dataset is then used to predict the number of cycles the media can be used at manufacturing scale (concurrent validation). Although, well accepted and widely practiced, there are challenges associated with extrapolating the laboratory scale data to manufacturing scale due to differences that may exist across scales. Factors that may be different include: level of impurities in the feed material, lot to lot variability in feedstock impurities, design of the column housing unit with respect to cleanability, and homogeneity of the column packing. In view of these challenges, there is a need for approaches that may be able to predict column underperformance at the manufacturing scale over the product lifecycle. In case such an underperformance is predicted, the operators can unpack and repack the chromatography column beforehand and thus avoid batch loss. Chemometrics offers one such solution. In this article, we present an application of chemometrics toward the analysis of a set of chromatography profiles with the intention of predicting the various events of column underperformance including the backpressure buildup and inefficient deoxyribonucleic acid clearance.

  11. 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

  12. 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.

  13. 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).

  14. 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.

  15. Silicon Materials Task of the Low Cost Solar Array Project, Phase 3. Effect of Impurities and Processing on Silicon Solar Cells

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    The effects of impurities, various thermochemical processes, and any impurity process interactions on the performance of terrestrial silicon solar cells are defined. Determinations of the segregation coefficients of tungsten, tantalum, and cobalt for the Czochralski pulling of silicon single crystals are reported. Sensitive neutron activation analysis was used to determine the metal impurity content of the silicon while atomic absorption was used to measure the metal content of the residual liquid from which the doped crystals were grown. Gettering of Ti doped silicon wafers improved cell performance by one to two percent for the highest temperatures and longest times. The HCl is more effective than POCl3 treatments for deactivating Ti but POCl3 and HCl produced essentially identical results for Mo or Fe.

  16. Determination of residual acetone and acetone related impurities in drug product intermediates prepared as Spray Dried Dispersions (SDD) using gas chromatography with headspace autosampling (GCHS).

    PubMed

    Quirk, Emma; Doggett, Adrian; Bretnall, Alison

    2014-08-01

    Spray Dried Dispersions (SDD) are uniform mixtures of a specific ratio of amorphous active pharmaceutical ingredient (API) and polymer prepared via a spray drying process. Volatile solvents are employed during spray drying to facilitate the formation of the SDD material. Following manufacture, analytical methodology is required to determine residual levels of the spray drying solvent and its associated impurities. Due to the high level of polymer in the SDD samples, direct liquid injection with Gas Chromatography (GC) is not a viable option for analysis. This work describes the development and validation of an analytical approach to determine residual levels of acetone and acetone related impurities, mesityl oxide (MO) and diacetone alcohol (DAA), in drug product intermediates prepared as SDDs using GC with headspace (HS) autosampling. The method development for these analytes presented a number of analytical challenges which had to be overcome before the levels of the volatiles of interest could be accurately quantified. GCHS could be used after two critical factors were implemented; (1) calculation and application of conversion factors to 'correct' for the reactions occurring between acetone, MO and DAA during generation of the headspace volume for analysis, and the addition of an equivalent amount of polymer into all reference solutions used for quantitation to ensure comparability between the headspace volumes generated for both samples and external standards. This work describes the method development and optimisation of the standard preparation, the headspace autosampler operating parameters and the chromatographic conditions, together with a summary of the validation of the methodology. The approach has been demonstrated to be robust and suitable to accurately determine levels of acetone, MO and DAA in SDD materials over the linear concentration range 0.008-0.4μL/mL, with minimum quantitation limits of 20ppm for acetone and MO, and 80ppm for DAA.

  17. Phase Transition of Two-Dimensional Ising Models on the Honeycomb and Related Lattices with Striped Random Impurities

    NASA Astrophysics Data System (ADS)

    Morita, Satoshi; Suzuki, Sei

    2016-01-01

    Two-dimensional Ising models on the honeycomb lattice and the square lattice with striped random impurities are studied to obtain their phase diagrams. Assuming bimodal distributions of the random impurities where all the non-zero couplings have the same magnitude, exact critical values for the fraction p of ferromagnetic bonds at the zero-temperature (T=0) are obtained. The critical lines in the p-T plane are drawn by numerically evaluating the Lyapunov exponent of random matrix products.

  18. Impurities in Kevlar 49 fibers

    SciTech Connect

    Pruneda, C.O.; Morgan, R.J.; Lim, R.; Gregory, L.J.; Fischer, J.W.

    1984-12-11

    The impurities in Kevlar 49 fibers (poly(p-phenylene terephthalamide)PPTA) are reported and discussed in terms of the fiber fabrication processes. These impurities were monitored by inductively coupled plasma emission and optical emission spectroscopy. The principal impurities Na/sub 2/SO/sub 4/ and total S were analyzed chemically. From these chemical analyses together with C, N, H elemental analyses we show that there are 1.5 wt % impurities present in Kevlar 49 fibers of which approx. 50% are in the form of Na/sub 2/SO/sub 4/ and the remainder probably in the form of benzene sulfonic -SO/sub 3/H PPTA side groups. There are 3 of these acid groups per each PPTA macromolecule. Organic impurities, such as terephthalic acid are discussed in the light of degradation studies of PPTA-H/sub 2/SO/sub 4/ spinning dopes. Electron microprobe x-ray spectroscopy and laser-induced damage studies were utilized to investigate the distribution of impurities through the fiber cross-section. The distribution of impurities throughout the fiber are determined by the fiber fabrication processes and are discussed at the microscopic and molecular level. The defects caused by these impurities and their effect on the deformation and failure modes are also considered. 22 references, 3 tables.

  19. Identification of iron oxide impurities in earliest industrial-scale processed platinum

    SciTech Connect

    Weerd, Jaap van der; Rehren, Thilo . E-mail: th.rehren@ucl.ac.uk; Firth, Steven; Clark, Robin J.H. . E-mail: r.j.h.clark@ucl.ac.uk

    2004-09-15

    A detailed investigation of iron oxide inclusions in a 19th century Russian platinum coin is presented. Such coins represent the products of the first industrial-scale purification of platinum metal. The processed metal is far from pure, however, and two types of iron oxide inclusions are identified by electron microprobe and Raman microscopy. The results show that the inclusions mainly consist of magnetite and haematite. The Raman band of magnetite at 668 cm{sup -1} was found to shift to about 680 cm{sup -1} with an increase in the average oxidation state of the iron. It is concluded that the iron oxides are formed during the heating of the platinum metal powder in the manufacturing process.

  20. Seventh workshop on the role of impurities and defects in silicon device processing

    SciTech Connect

    1997-08-01

    This workshop is the latest in a series which has looked at technological issues related to the commercial development and success of silicon based photovoltaic (PV) modules. PV modules based on silicon are the most common at present, but face pressure from other technologies in terms of cell performance and cell cost. This workshop addresses a problem which is a factor in the production costs of silicon based PV modules.

  1. Determination of elemental impurities in pharmaceutical products and related matrices by ICP-based methods: a review.

    PubMed

    Barin, Juliano S; Mello, Paola A; Mesko, Marcia F; Duarte, Fabio A; Flores, Erico M M

    2016-07-01

    Interest in the determination of elemental impurities in pharmaceuticals has increased in recent years because of changes in regulatory requirements and the need for changing or updating the current limit tests recommended in pharmacopeias. Inductively coupled plasma (ICP) optical emission spectrometry and ICP mass spectrometry are suitable alternatives to perform multielemental analysis for this purpose. The main advantages and limitations of these techniques are described, covering the applications reported in the literature in the last 10 years mainly for active pharmaceutical ingredients, raw materials, and pharmaceutical dosage forms. Strategies used for sample preparation, including dissolution in aqueous or organic solvents, extraction, wet digestion and combustion methods are described, as well as direct solid analysis and ICP-based systems applied for speciation analysis. Interferences observed during the analysis of pharmaceutical products using ICP-based methods are discussed. Methods currently recommended by pharmacopeias for elemental impurities are also covered, showing that the use of ICP-based methods could be considered as a trend in the determination of these impurities in pharmaceuticals. However, the development of a general method that is accurate for all elemental impurities and the establishment of an official method are still challenges. In this regard, the main drawbacks and suitable alternatives are discussed.

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

    SciTech Connect

    McHugo, S.A.; Hieslmair, H.; Weber, E.R.; Rosenblum, M.D.; Kalejs, J.P.

    1996-11-01

    Interactions between structural defects and metallic impurities were studied in multicrystalline silicon for solar cells applications. The objective was to gain insight into the relationship between solar cell processing, metallic impurity behavior and the resultant effect on material/device performance. With an intense synchrotron x-ray source, high sensitivity x-ray fluorescence measurements were utilized to determine impurity distributions with a spatial resolution of {approx} 1{micro}m. Diffusion length mapping and final solar cell characteristics gauged material/device performance. The materials were tested in both the as-grown state and after full solar cell processing. Iron and nickel metal impurities were located at structural defects in as-grown material, while after solar cell processing, both impurities were still observed in low performance regions. These results indicate that multicrystalline silicon solar cell performance is directly related to metal impurities which are not completely removed during typical processing treatments. A discussion of possible mechanisms for this incomplete removal is presented.

  3. Caprylic acid-induced impurity precipitation from protein A capture column elution pool to enable a two-chromatography-step process for monoclonal antibody purification.

    PubMed

    Zheng, Ji; Wang, Lu; Twarowska, Barbara; Laino, Sarah; Sparks, Colleen; Smith, Timothy; Russell, Reb; Wang, Michelle

    2015-01-01

    This article presents the use of caprylic acid (CA) to precipitate impurities from the protein A capture column elution pool for the purification of monoclonal antibodies (mAbs) with the objective of developing a two chromatography step antibody purification process. A CA-induced impurity precipitation in the protein A column elution pool was evaluated as an alternative method to polishing chromatography techniques for use in the purification of mAbs. Parameters including pH, CA concentrations, mixing time, mAb concentrations, buffer systems, and incubation temperatures were evaluated on their impacts on the impurity removal, high-molecular weight (HMW) formation and precipitation step yield. Both pH and CA concentration, but not mAb concentrations and buffer systems, are key parameters that can affect host-cell proteins (HCPs) clearance, HMW species, and yield. CA precipitation removes HCPs and some HMW species to the acceptable levels under the optimal conditions. The CA precipitation process is robust at 15-25°C. For all five mAbs tested in this study, the optimal CA concentration range is 0.5-1.0%, while the pH range is from 5.0 to 6.0. A purification process using two chromatography steps (protein A capture column and ion exchange polishing column) in combination with CA-based impurity precipitation step can be used as a robust downstream process for mAb molecules with a broad range of isoelectric points. Residual CA can be effectively removed by the subsequent polishing cation exchange chromatography.

  4. Improved Performance of the Alkaline-Side CSEX Process for Cesium Extraction from Alkaline High-Level Waste Obtained by Characterization of the Effect of Surfactant Impurities

    SciTech Connect

    Delmau, L.H.

    1999-11-04

    Improved understanding and performance of the alkaline-side CSEX process has been obtained through the characterization of impurity effects that hinder complete stripping of cesium from the solvent. It is shown in this report that tests of the alkaline-side CSEX process conducted in the summer and fall of 1998 were complicated by the presence of common surfactant anions, undecyl- and dodecylsulfonate, as trace impurities in the two simulants tested. This conclusion was drawn from the results of a series of systematic extraction tests followed by a definitive identification by electrospray mass spectrometry (ES-MS). Based on this understanding, a straightforward preventative measure involving the addition of a lipophilic tertiary amine extractant at a small concentration to the solvent is proposed and demonstrated. As part of the task ''Fission Product Solvent Extraction'' supported by the Efficient Separations and Processing Crosscutting Program within the USDOE Office of Environmental Management, the alkaline-side CSEX process has been developed for removal of radio-cesium ({sup 137}Cs) from alkaline high-level wastes stored in underground tanks at the Hanford Site and Savannah River Site (SRS). As described in a previous report, tests conducted in Fiscal Year 1998 generally demonstrated performance meeting the requirements for cesium removal from the waste to be treated at the SRS. However, discrepancies in stripping behavior were shown to arise from unidentified differences ''in the batches of waste simulant employed for testing. Various effects such as solvent impurities, kinetics, contacting method, and counting method were eliminated as possible causes of the observed discrepancies. Tests in Fiscal Year 1999 reported herein confirmed the earlier suspicion that the simulants contained lipophilic anionic impurities. Extraction tests demonstrated that the impurities could be concentrated in the solvent, and by ES-MS in the negative-ion mode it was possible to

  5. Unified planar process for fabricating heterojunction bipolar transistors and buried-heterostructure lasers utilizing impurity-induced disordering

    SciTech Connect

    Thornton, R.L.; Mosby, W.J.; Chung, H.F.

    1988-12-26

    We describe results on a novel geometry of heterojunction bipolar transistor that has been realized by impurity-induced disordering. This structure is fabricated by a method that is compatible with techniques for the fabrication of low threshold current buried-heterostructure lasers. We have demonstrated this compatibility by fabricating a hybrid laser/transistor structure that operates as a laser with a threshold current of 6 mA at room temperature, and as a transistor with a current gain of 5.

  6. Unified planar process for fabricating heterojunction bipolar transistors and buried-heterostructure lasers utilizing impurity-induced disordering

    NASA Astrophysics Data System (ADS)

    Thornton, R. L.; Mosby, W. J.; Chung, H. F.

    1988-12-01

    We describe results on a novel geometry of heterojunction bipolar transistor that has been realized by impurity-induced disordering. This structure is fabricated by a method that is compatible with techniques for the fabrication of low threshold current buried-heterostructure lasers. We have demonstrated this compatibility by fabricating a hybrid laser/transistor structure that operates as a laser with a threshold current of 6 mA at room temperature, and as a transistor with a current gain of 5.

  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. Impurity-induced divertor plasma oscillations

    DOE PAGES

    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

  9. Influence of crystallization front direction on the Mg-related impurity centers incorporation in bulk GaN:Mg grown by HNPS method

    NASA Astrophysics Data System (ADS)

    Sadovyi, B.; Amilusik, M.; Litwin-Staszewska, E.; Bockowski, M.; Grzegory, I.; Porowski, S.; Fijalkowski, M.; Rudyk, V.; Tsybulskyi, V.; Panasyuk, M.; Karbovnyk, I.; Kapustianyk, V.

    2016-08-01

    We studied the incorporation of Mg-related impurity centers in GaN crystals depending on the direction of the crystallization front. Two series of GaN crystals - (i) undoped and (ii) Mg-doped - were grown by High Nitrogen Pressure Solution (HNPS) method under otherwise identical conditions. Each series contained four samples with (10 1 bar 0) , (11 2 bar 0) , (20 2 bar 1 bar) and (20 2 bar 1) orientations. The low-temperature photoluminescence (PL) spectroscopy was used for characterization of the obtained crystals. The observed differences in the PL spectra of GaN:Mg crystals suggested that Mg incorporation in GaN grown by HNPS method depends considerably on the orientation of crystallization front. The concentration of Mg impurity incorporated into the GaN crystals subsequently increases for the following sequence of planes: (10 1 bar 0) , (11 2 bar 0) , (20 2 bar 1 bar) and (20 2 bar 1) . For (10 1 bar 0) , (11 2 bar 0) and (20 2 bar 1 bar) planes the blue band is related only to ON - MgGa donor-acceptor pair (DAP) transitions, while for (20 2 bar 1) plane the incorporation of Mg-H complexes occurs additionally to the formation ON - MgGa DAP.

  10. Development and validation of a stability-indicating RP-HPL C-CAD method for gabapentin and its related impurities in presence of degradation products.

    PubMed

    Ragham, Pramod Kumar; Chandrasekhar, Kothapalli B

    2016-06-01

    The objective of the current study was to develop and validate a sensitive and specific LC-MS compatible stability indicating reversed phase liquid chromatographic method for the quantitative determination of Gabapentin and its related substances using Corona charged aerosol detection (CAD). The chromatographic conditions were optimized using a Kinetix Biphenyl column with gradient elution using a mobile phase composed of pH 4.2 ammonium acetate, acetonitrile, and methanol. Forced degradation was observed in basic and peroxide conditions and the major degradants were identified by LC-MS/MS analysis. The developed RP-HPLC CAD method was validated according to ICH guidelines. The LOD and LOQ values for Gabapentin and all its related impurities ranged from 0.075μg/mL to 0.18μg/mL and 0.25μg/mL to 0.60μg/mL, respectively. The recovery for all impurities ranged from 91.0 to 105.6%w/w. Solutions were stable for 7days at room temperature. The validated method produced acceptable precision, linearity, accuracy, robustness and ruggedness. PMID:27018505

  11. Effect of self-organization, defects, impurities, and autocatalytic processes on the parameters of ZnO films and nanorods

    SciTech Connect

    Mezdrogina, M. M. Eremenko, M. V.; Levitskii, V. S.; Petrov, V. N.; Terukov, E. I.; Kaidashev, E. M.; Langusov, N. V.

    2015-11-15

    The effects of the parameters of ZnO-film deposition onto different substrates using the method of ac magnetron sputtering in a gas mixture of argon and oxygen hare studied. The phenomenon of self-organization is observed, which leads to invariability of the surface morphology of the ZnO films upon a variation in the substrate materials and deposition parameters. The parameters of the macro- and micro-photoluminescence spectra of the films differ insignificantly from the parameters of the photoluminescence spectra of bulk ZnO crystals obtained by the method of hydrothermal growth. The presence of intense emission with a narrow full-width at half-maximum (FWHM) in different regions of the spectrum allows ZnO films obtained by magnetron sputtering doped with rare-earth metal impurities (REIs) to be considered as a promising material for the creation of optoelectronic devices working in a broad spectral range. The possibility of the implementation of magnetic ordering upon legierung with REIs significantly broadens the functional possibilities of ZnO films. The parameters of the photoluminescence spectra of ZnO nanorods are determined by their geometrical parameters and by the concentration and type of the impurities introduced.

  12. 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.

  13. Substitutional impurity in the graphene quantum dots

    NASA Astrophysics Data System (ADS)

    Sierański, K.; Szatkowski, J.

    2015-09-01

    The process of formation of the localized defect states due to substitutional impurity in sp2-bonded graphene quantum dot is considered using a simple tight-binding-type calculation. We took into account the interaction of the quantum dot atoms surrounding the substitutional impurity from the second row of elements. To saturate the external dangling sp2 orbitals of the carbon additionally 18 hydrogen atoms were introduced. The chemical formula of the quantum dot is H18C51X, where X is the symbol of substitutional atom. The position of the localized levels is determined relative to the host-atoms (C) εp energies. We focused on the effect of substitutional doping by the B, N and O on the eigenstate energies and on the total energy change of the graphene dots including for O the effect of lattice distorsion. We conclude that B, N, and O can form stable substitutional defects in graphene quantum dot.

  14. The Effect of Hydrogen Annealing on the Impurity Content of Alumina-Forming Alloys

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2000-01-01

    Previously, the effect of hydrogen annealing on increasing the adhesion of Al2O3 scales had been related to the effective desulfurization that occurred during this process. The simultaneous reduction of other impurities has now been re-examined for up to 20 impurity elements in the case of five different alloys (NiCrAl, FeCrAl, PWA 1480, Rene'142, and Rene'N5). Hydrogen annealing produced measurable reductions in elemental concentration for B, C, Na, Mg, P, K, Sr, or Sn in varying degrees for at least one and up to three of these alloys. No single element was reduced by hydrogen annealing for all the alloys except sulfur. In many cases spalling occurred at low levels of these other impurities, while in other cases the scales were adherent at high levels of the impurities. No impurity besides sulfur was strongly correlated with adhesion.

  15. 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.

  16. 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

  17. Elemental Impurities in Pharmaceutical Excipients.

    PubMed

    Li, Gang; Schoneker, Dave; Ulman, Katherine L; Sturm, Jason J; Thackery, Lisa M; Kauffman, John F

    2015-12-01

    Control of elemental impurities in pharmaceutical materials is currently undergoing a transition from control based on concentrations in components of drug products to control based on permitted daily exposures in drug products. Within the pharmaceutical community, there is uncertainty regarding the impact of these changes on manufactures of drug products. This uncertainty is fueled in part by a lack of publically available information on elemental impurity levels in common pharmaceutical excipients. This paper summarizes a recent survey of elemental impurity levels in common pharmaceutical excipients as well as some drug substances. A widely applicable analytical procedure was developed and was shown to be suitable for analysis of elements that are subject to United States Pharmacopoeia Chapter <232> and International Conference on Harmonization's Q3D Guideline on Elemental Impurities. The procedure utilizes microwave-assisted digestion of pharmaceutical materials and inductively coupled plasma mass spectrometry for quantitative analysis of these elements. The procedure was applied to 190 samples from 31 different excipients and 15 samples from eight drug substances provided through the International Pharmaceutical Excipient Council of the Americas. The results of the survey indicate that, for the materials included in the study, relatively low levels of elemental impurities are present. PMID:26398581

  18. Elemental Impurities in Pharmaceutical Excipients.

    PubMed

    Li, Gang; Schoneker, Dave; Ulman, Katherine L; Sturm, Jason J; Thackery, Lisa M; Kauffman, John F

    2015-12-01

    Control of elemental impurities in pharmaceutical materials is currently undergoing a transition from control based on concentrations in components of drug products to control based on permitted daily exposures in drug products. Within the pharmaceutical community, there is uncertainty regarding the impact of these changes on manufactures of drug products. This uncertainty is fueled in part by a lack of publically available information on elemental impurity levels in common pharmaceutical excipients. This paper summarizes a recent survey of elemental impurity levels in common pharmaceutical excipients as well as some drug substances. A widely applicable analytical procedure was developed and was shown to be suitable for analysis of elements that are subject to United States Pharmacopoeia Chapter <232> and International Conference on Harmonization's Q3D Guideline on Elemental Impurities. The procedure utilizes microwave-assisted digestion of pharmaceutical materials and inductively coupled plasma mass spectrometry for quantitative analysis of these elements. The procedure was applied to 190 samples from 31 different excipients and 15 samples from eight drug substances provided through the International Pharmaceutical Excipient Council of the Americas. The results of the survey indicate that, for the materials included in the study, relatively low levels of elemental impurities are present.

  19. 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.

  20. 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.

  1. Detection of acetylene impurities in ethylene and polyethylene manufacturing processes using tunable diode laser spectroscopy in the 3-μm range

    NASA Astrophysics Data System (ADS)

    Kluczynski, P.; Jahjah, M.; Nähle, L.; Axner, O.; Belahsene, S.; Fischer, M.; Koeth, J.; Rouillard, Y.; Westberg, J.; Vicet, A.; Lundqvist, S.

    2011-11-01

    Using recently developed GaInAsSb/AlGaInAsSb DFB lasers, tunable diode laser spectroscopy (TDLS) has been extended into the 3-μm wavelength region for the detection of acetylene impurities in hydrocarbon compounds encountered in ethylene manufacturing. Measurements of acetylene in pure polymer grade ethylene and in a gas mixture of ethylene and ethane typical of the process stream around a hydrogenation reactor have been performed. Using a procedure incorporating subtraction of a hydrocarbon background spectrum a detection limit of 5 ppb m was achieved under ordinary laboratory conditions. Under forced temperature cycling conditions, the detection limit deteriorated to 180 ppb m, due to temperature drift caused by optical interferences generated by reflections in the laser TO8 can.

  2. In-situ impurity measurements in PDX Edge plasma

    SciTech Connect

    Staib, P.; Dylla, H.F.; Rossnagel, S.M.

    1980-07-01

    The surface analysis station of PDX combines several surface analysis techniques (AES, XPS, SIMS) for in-situ measurement of impurity fluxes in the edge-plasma. The major impurities deposited on a sample surface during nondiverted PDX discharges are oxygen, titanium (limiter material) and chlorine. The impurity fluxes measured at different radial positions decreased by a factor of ten from the plasma edge to the wall. The sample surface collecting the impurity ions is located behind a circular aperture. The observed broadening of the deposition profile of Ti relative to the aperture diameter enables an estimate to be made of the ratio of charge state/energy of Ti ions in the edge plasma. Time-resolved analyses of the deposited impurities are presented which indicate that the time behavior for various impurities may be quite different for different impurity species. This aspect is discussed in relation to probable impurity release mechanisms.

  3. Application of LC-MS(n) in conjunction with mechanism-based stress studies in the elucidation of drug impurity structure: rapid identification of a process impurity in betamethasone 17-valerate drug substance.

    PubMed

    Li, Min; Lin, Mingxiang; Rustum, Abu

    2008-12-15

    Through a case study, the use of LC-MS(n) technique in conjunction with a mechanism-based stress study is shown to be a very effective way in the rapid elucidation of unknown drug impurities. In this case, the drug substance sample was first analyzed using LC-MS(n) through which the unknown species was found to be a valeryl-containing, isomeric impurity of the active pharmaceutical ingredient (API), betamethasone 17-valerate, based on its molecular ion and major fragments. Since a substantial knowledge regarding a large number of isomeric impurities of betamethasone has been accumulated in the literature as well as in our laboratory, a hydrolytic stress study (forced degradation) of the isolated unknown species was then designed and carried out accordingly in order to remove the valeryl group from the unknown species. During the stress study, a betamethasone isomer was generated as expected. However, a new unknown species isomeric to betamethasone 17-valerate was also formed unexpectedly. By comparing the UV spectra and more importantly MS(n) fragmentation patterns of the two newly formed species with those of betamethasone, dexamethasone, betamethasone 17-valerate, and betamethasone 21-valerate, these two unknown species generated in the stress study were identified as dexamethasone and dexamethasone 21-valerate, respectively. Based on the plausible reaction mechanism of the forced degradation, the original impurity present in betamethasone 17-valerate drug substance was then identified as dexamethasone 17-valerate; the structure assignment was later confirmed by various 1D and 2D NMR experiments. The efficient conversion from dexamethasone 17-valerate to dexamethasone 21-valerate was also observed during a 2D NMR acquisition of the isolated dexamethasone 17-valerate sample.

  4. Isolation and Structural Elucidation of an Unknown Impurity in Prasugrel by Semi-Preparative Liquid Chromatography.

    PubMed

    Liu, Chao; Yu, Zhangxin; Wang, Fujun; Zhong, Xing; Jiang, Li; Zhang, Feifei; Tang, Yinxia; Yan, Zhaohua; Zeng, Su; Pu, Tong

    2015-08-01

    A brand-new impurity was detected by RP-HPLC in the prasugrel. The impurity was named as Impurity X. Impurity X was isolated by using semi-preparative HPLC followed by characterization using nuclear magnetic resonance spectroscopy and liquid chromatography-mass spectrometry. The functional mechanism of Impurity X was speculated. Impurity X could be controlled in the manufacture process of the prasugrel active pharmaceutical ingredient effectively. PMID:25644811

  5. Impurity transport in Tokamaks

    NASA Astrophysics Data System (ADS)

    Amano, T.

    1983-12-01

    Theoretical and experimental efforts directed towards gaining an understanding of impurity behavior in Tokamaks are reviewed. In the Alcator Tokamak experiments, a laser blow-off technique was used to introduce trace amounts of impurities into ohmically heated plasmas. After a series of experiments in which they injected Si, Al, Fe, Mo impurities, an equation representing empirical impurity confinement time was derived. The scaling of this equation was compared with the results of impurity injection experiments on other Tokamaks, FT-I, PDX, TFR, ISX-B. Impurity confinement times in all these cases agree remarkably well, except for the TFR confinement times, which were about a factor of two larger than predicted. In the presence of intense neutral beam injection impurity ions behave differently. Specifically, in the ISX-B experiments, a marked accumulation of impurity ions toward the center of the plasma was observed in the case of counter neutral beam injection. This was interpreted semi-quantitatively by the neoclassical effect of the rotation of the plasma driven by the neutral beam.

  6. Quantum impurity in a Luttinger liquid: Exact solution of the Kane-Fisher model

    NASA Astrophysics Data System (ADS)

    Rylands, Colin; Andrei, Natan

    2016-09-01

    A Luttinger liquid coupled to a quantum impurity describes a large number of physical systems. The Hamiltonian consists of left- and right-moving fermions interacting among themselves via a density-density coupling and scattering off a localized transmitting and reflecting impurity. We solve exactly the Hamiltonian by means of an incoming-outgoing scattering Bethe basis which properly incorporates all scattering processes. A related model, the weak-tunneling model, wherein the impurity is replaced by a tunnel junction, is solved by the same method. The consistency of the construction is established through a generalized Yang-Baxter relation. Periodic boundary conditions are imposed and the resulting Bethe ansatz equations are derived by means of the off-diagonal Bethe ansatz approach. We derive the spectrum of the model for all coupling constant regimes and calculate the impurity free energy. We discuss the low energy behavior of the systems for both repulsive and attractive interactions.

  7. Effect of temperature and potassium chloride impurity on the relative ⟨101̅0⟩ tilt grain boundary and surface free energies in ice.

    PubMed

    Di Prinzio, Carlos L; Druetta, Esteban; Nasello, Olga B

    2014-11-26

    The ratio of the grain boundary free energies relative to the surface free energies γgb/γs can be determined by measuring the root angles of the grooves formed at the intersection of the grain boundary with the free surface. The grooves were copied by plastic replicas, and the topographic details were revealed with a laser confocal 3D microscope. Values of γgb/γs were determined for high purity and potassium chloride doped ice bicrystals annealed at -5 and -18 °C. The studied samples were ⟨101̅0⟩/ψ tilt grain boundaries with ψ between 10 and 180°. The used KCl concentrations were 1 and 10 μmol/l, and the conductivity of the pure ice was 0.3 μS. ⟨101̅0⟩/60° grain boundary relative energies were also determined for different grain boundary inclinations. All the γgb/γs obtained values were analyzed and compared using the CSL (coincidence site lattice) theory. For pure samples annealed at -18 °C, an important variation of γgb/γs with the grain boundary inclination was found. In general, a remarkable correspondence between CSL planar density Γ and γgb/γs was observed. Results also showed that the increase of temperature and the impurity changes significantly γgb/γs.

  8. Selective determination of dimenhydrinate in presence of six of its related substances and potential impurities using a direct GC/MS method

    PubMed Central

    Belal, Tarek S.; Abdel-Hay, Karim M.; Clark, C. Randall

    2015-01-01

    A novel simple, direct and selective gas chromatography–mass spectrometry (GC/MS) procedure was developed for the determination of the antihistamine drug dimenhydrinate (DMH) in presence of six of its related substances and potential impurities, namely, diphenylmethane, diphenylmethanol, benzophenone, orphenadrine, caffeine and 8-chlorocaffeine. The method involved resolution of the underivatized compounds using a trifluoropropylmethyl polysiloxane (Rtx-200) capillary column and the mass spectrometric detection was carried out in the electron-impact (EI) mode. Excellent baseline separation of DMH and the cited related substances was achieved in less than 15 min. Quantification of the parent drug DMH was based on measuring its peak area. The reliability and analytical performance of the proposed method were validated with respect to linearity, range, precision, accuracy, specificity, robustness, detection and quantification limits. Calibration curve of DMH was linear over the range 50–500 μg/mL with determination coefficient (R2) = 0.9982. The proposed method was successfully applied for the assay of DMH in tablets dosage form with recoveries >96.80%. PMID:26843970

  9. Relative Humidity and the Susceptibility of Austenitic Stainless Steel to Stress Corrosion Cracking in an impure Plutonium Oxide Environment

    SciTech Connect

    Zapp, P.; Duffey, J.; Lam, P.; Dunn, K.

    2010-05-05

    Laboratory tests to investigate the corrosivity of moist plutonium oxide/chloride salt mixtures on 304L and 316L stainless steel coupons showed that corrosion occurred in selected samples. The tests exposed flat coupons for pitting evaluation and 'teardrop' stressed coupons for stress corrosion cracking (SCC) evaluation at room temperature to various mixtures of PuO{sub 2} and chloride-bearing salts for periods up to 500 days. The exposures were conducted in sealed containers in which the oxide-salt mixtures were loaded with about 0.6 wt % water from a humidified helium atmosphere. Observations of corrosion ranged from superficial staining to pitting and SCC. The extent of corrosion depended on the total salt concentration, the composition of the salt and the moisture present in the test environment. The most significant corrosion was found in coupons that were exposed to 98 wt % PuO{sub 2}, 2 wt % chloride salt mixtures that contained calcium chloride and 0.6 wt% water. SCC was observed in two 304L stainless steel teardrop coupons exposed in solid contact to a mixture of 98 wt % PuO{sub 2}, 0.9 wt % NaCl, 0.9 wt % KCl, and 0.2 wt % CaCl{sub 2}. The cracking was associated with the heat-affected zone of an autogenous weld that ran across the center of the coupon. Cracking was not observed in coupons exposed to the headspace gas above the solid mixture, or in coupons exposed to other mixtures with either no CaCl{sub 2} or 0.92 wt% CaCl{sub 2}. SCC was present where the 0.6 wt % water content exceeded the value needed to fully hydrate the available CaCl{sub 2}, but was absent where the water content was insufficient. These results reveal the significance of the relative humidity in the austenitic stainless steels environment to their susceptibility to corrosion. The relative humidity in the test environment was controlled by the water loading and the concentration of the hydrating salts such as CaCl{sub 2}. For each salt or salt mixture there is a threshold relative

  10. Relational Knowledge in Higher Cognitive Processes.

    ERIC Educational Resources Information Center

    Halford, Graeme S.

    Explicit representation of relations plays some role in virtually all higher cognitive processes, but relational knowledge has seldom been investigated systematically. This paper considers how relational knowledge is involved in some tasks that have been important to cognitive development, including transitivity, the balance scale, classification…

  11. An overview of laboratory studies on the energetic processes in water-rich ices containing organic impurities at outer Solar System temperatures.

    NASA Astrophysics Data System (ADS)

    Gudipati, M. S.; Allamandola, L. J.

    2006-12-01

    Solid water-rich ice is an important constituent in our Solar System. Planets such as Earth and Mars, Moons such as Europa and Enceladus, Comets, rings of Saturn, and KBOs are covered with solid water ices. Thus, understanding the intricate physics and chemistry of these ices is a non-trivial and non-negligible task that needs both laboratory and in-situ observational work to make advances in this field. Over the past several years, we have been systematically studying VUV-radiation processing of organic impurities embedded in water-ices in the temperature range between 20 K and 180 K. Since PAHs are abundant extraterrestrial species and their optical strong absorption occurs in the UV-VIS-NIR region (0.2 -- 0.9 μ m) where water-ice is transparent, we have focused on water rich ices containing PAHs. During these in-situ studies we discovered several counter-intuitive phenomena (see for example: Gudipati {&} Allamandola, 2006, Astrophys. J. 638, 286 {&} J. Phys. Chem. A 110, 9020 and references therein): \\begin{itemize} PAHs embedded in cryogenic water-ice are easily and efficiently ionized (>80{%}, i.e., near quantitative ion yields) to the cation form by VUV photons. In water ice, PAH ionization energy is lowered by up to 2 eV compared to the gas-phase, in agreement with recent theoretical predictions. PAH cations are stabilized in water ice to temperatures as high as 120 K. Sequential photoionization leading to the formation and stabilization of doubly positively charged organic (PAH) species in water ice has also been found. Electrons are stored in these energy processed water-ices doped with organic impurities. These findings have a range of applications to understanding the geology, chemistry, and physics of icy bodies in the outer Solar System such as coloration, energy budget, outbursts and atmospheres. These and other applications to outer Solar System will be discussed. Acknowledgments: This work was supported by grants from NASA's Exobiology

  12. Existence of zero-energy impurity states in different classes of topological insulators and superconductors and their relation to topological phase transitions

    NASA Astrophysics Data System (ADS)

    Kimme, Lukas; Hyart, Timo

    2016-01-01

    We consider the effects of impurities on topological insulators and superconductors. We start by identifying the general conditions under which the eigenenergies of an arbitrary Hamiltonian H belonging to one of the Altland-Zirnbauer symmetry classes undergo a robust zero energy crossing as a function of an external parameter which can be, for example, the impurity strength. We define a generalized root of detH and use it to predict or rule out robust zero-energy crossings in all symmetry classes. We complement this result with an analysis based on almost degenerate perturbation theory, which allows a derivation of the asymptotic low-energy behavior of the ensemble averaged density of states ρ ˜Eα for all symmetry classes and makes it transparent that the exponent α does not depend on the choice of the random matrix ensemble. Finally, we show that a lattice of impurities can drive a topologically trivial system into a nontrivial phase, and in particular we demonstrate that impurity bands carrying extremely large Chern numbers can appear in different symmetry classes of two-dimensional topological insulators and superconductors. We use the generalized root of detH (k ) to reveal a spiderweblike momentum space structure of the energy gap closings that separate the topologically distinct phases in px+i py superconductors in the presence of an impurity lattice.

  13. The influence of a homologous protein impurity on lysozyme crystal growth

    NASA Astrophysics Data System (ADS)

    Bhamidi, V.; Hanson, B. L.; Edmundson, A.; Skrzypczak-Jankun, E.; Schall, C.

    1999-08-01

    The effect of a structurally similar protein impurity, turkey ( Meleagris gallopavo) egg-white lysozyme (TEWL) on crystallization of the host protein, hen-egg-white lysozyme (HEWL) from chicken ( Gallus gallus) was studied under varying impurity and host solution concentrations. A change in morphology is observed when crystals of HEWL are grown in the presence of TEWL. As the relative amount of TEWL increases, HEWL crystals become more elongated in the [0 0 1] direction. Elongation is more pronounced in samples with lower initial concentrations of HEWL than in samples with higher initial concentrations. This behavior is consistent with that of impurities in small molecule crystal growth and with predictions based on the Kubota-Mullin model. The observed effect on the growth process can be attributed to the apparent inhibition in the [1 1 0] crystal growth direction of HEWL by TEWL since slowly growing faces become dominant faces in crystal growth. Incorporation of TEWL into HEWL crystals grown in a sitting drop batch method was measured using cation exchange chromatography. The results indicate that impurity incorporation is associated with increasing supersaturation. This conclusion is consistent with a kinetically controlled process of impurity incorporation. The observed impurity effects are most probably associated with the interchange of glutamine in position 41 of HEWL by histidine in TEWL.

  14. 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.

  15. Carbon-Impurity Affected Depth Elemental Distribution in Solution-Processed Inorganic Thin Films for Solar Cell Application.

    PubMed

    Rehan, Shanza; Kim, Ka Young; Han, Jeonghyeob; Eo, Young-Joo; Gwak, Jihye; Ahn, Seung Kyu; Yun, Jae Ho; Yoon, KyungHoon; Cho, Ara; Ahn, SeJin

    2016-03-01

    A common feature of the inorganic thin films including Cu(In,Ga)(S,Se)2 fabricated by nonvacuum solution-based approaches is the doubled-layered structure, with a top dense inorganic film and a bottom carbon-containing residual layer. Although the latter has been considered to be the main efficiency limiting factor, (as a source of high series resistance), the exact influence of this layer is still not clear, and contradictory views are present. In this study, using a CISe as a model system, we report experimental evidence indicating that the carbon residual layer itself is electrically benign to the device performance. Conversely, carbon was found to play a significant role in determining the depth elemental distribution of final film, in which carbon selectively hinders the diffusion of Cu during selenization, resulting in significantly Cu-deficient top CISe layer while improving the film morphology. This carbon-affected compositional and morphological impact on the top CISe films is a determining factor for the device efficiency, which was supported by the finding that CISe solar cells processed from the precursor film containing intermediate amount of carbon demonstrated high efficiencies of up to 9.15% whereas the performances of the devices prepared from the precursor films with very high and very low carbon were notably poor. PMID:26817680

  16. 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.

  17. 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.

  18. Effect of inactive impurities on the burning of ICF targets

    SciTech Connect

    Gus'kov, S. Yu.; Il'in, D. V.; Sherman, V. E.

    2011-12-15

    The efficiency of thermonuclear burning of the spherical deuterium-tritium (DT) plasma of inertial confinement fusion (ICF) targets in the presence of low-Z impurities (such as lithium, carbon, or beryllium) with arbitrary concentrations is investigated. The effect of impurities produced due to the mixing of the thermonuclear fuel with the material of the structural elements of the target during its compression on the process of target burning is studied, and the possibility of using solid noncryogenic thermonuclear fuels in ICF targets is analyzed. Analytical dependences of the ignition energy and target thermonuclear gain on the impurity concentration are obtained. The models are constructed for homogeneous and inhomogeneous plasmas for the case in which the burning is initiated in the central heated region of the target and then propagates into the surrounding relatively cold fuel. Two possible configurations of an inhomogeneous plasma, namely, an isobaric configuration formed in the case of spark ignition of the target and an isochoric configuration formed in the case of fast ignition, are considered. The results of numerical simulations of the burning of the DT plasma of ICF targets in a wide range of impurity concentrations are presented. The simulations were performed using the TEPA one-dimensional code, in which the thermonuclear burning kinetics is calculated by the Monte Carlo method. It is shown that the strongest negative effect related to the presence of impurities is an increase in the energy of target ignition. It is substantiated that the most promising solid noncryogenic fuel is DT hydride of beryllium (BeDT). The requirements to the plasma parameters at which BeDT can be used as a fuel in noncryogenic ICF targets are determined. Variants of using noncryogenic targets with a solid thermonuclear fuel are proposed.

  19. Relating Hippocampus to Relational Memory Processing across Domains and Delays

    PubMed Central

    Monti, Jim M.; Cooke, Gillian E.; Watson, Patrick D.; Voss, Michelle W.; Kramer, Arthur F.; Cohen, Neal J.

    2015-01-01

    The hippocampus has been implicated in a diverse set of cognitive domains and paradigms, including cognitive mapping, long-term memory, and relational memory, at long or short study–test intervals. Despite the diversity of these areas, their association with the hippocampus may rely on an underlying commonality of relational memory processing shared among them. Most studies assess hippocampal memory within just one of these domains, making it difficult to know whether these paradigms all assess a similar underlying cognitive construct tied to the hippocampus. Here we directly tested the commonality among disparate tasks linked to the hippocampus by using PCA on performance from a battery of 12 cognitive tasks that included two traditional, long-delay neuropsychological tests of memory and two laboratory tests of relational memory (one of spatial and one of visual object associations) that imposed only short delays between study and test. Also included were different tests of memory, executive function, and processing speed. Structural MRI scans from a subset of participants were used to quantify the volume of the hippocampus and other subcortical regions. Results revealed that the 12 tasks clustered into four components; critically, the two neuropsychological tasks of long-term verbal memory and the two laboratory tests of relational memory loaded onto one component. Moreover, bilateral hippocampal volume was strongly tied to performance on this component. Taken together, these data emphasize the important contribution the hippocampus makes to relational memory processing across a broad range of tasks that span multiple domains. PMID:25203273

  20. Cleaning air from multicomponent impurities of volatile organic compounds by pulsed corona discharge

    NASA Astrophysics Data System (ADS)

    Filatov, I. E.; Uvarin, V. V.; Kuznetsov, D. L.

    2016-09-01

    The relative efficiency of the removal of impurities from airflow under the action of pulsed corona discharge has been studied by processing model mixtures of air with volatile organic compounds (VOCs). A method is proposed that allows the influence of the VOC structure on its reactivity to be directly determined. For this purpose, it is suggested to calculate a relative energy parameter characterizing the reactivity of a given impurity component in the framework of the method employed. This approach significantly intensifies the process of determination of the energy parameters of impurity removal and can be used as a criterion for comparative estimation of the efficiency of various methods employing nonequilibrium plasma for cleaning air from VOCs.

  1. Rearrangements of organic peroxides and related processes

    PubMed Central

    Yaremenko, Ivan A; Vil’, Vera A; Demchuk, Dmitry V

    2016-01-01

    Summary This review is the first to collate and summarize main data on named and unnamed rearrangement reactions of peroxides. It should be noted, that in the chemistry of peroxides two types of processes are considered under the term rearrangements. These are conventional rearrangements occurring with the retention of the molecular weight and transformations of one of the peroxide moieties after O–O-bond cleavage. Detailed information about the Baeyer−Villiger, Criegee, Hock, Kornblum−DeLaMare, Dakin, Elbs, Schenck, Smith, Wieland, and Story reactions is given. Unnamed rearrangements of organic peroxides and related processes are also analyzed. The rearrangements and related processes of important natural and synthetic peroxides are discussed separately. PMID:27559418

  2. A feasible approach to evaluate the relative reactivity of NHS-ester activated group with primary amine-derivatized DNA analogue and non-derivatized impurity.

    PubMed

    Dou, Shuping; Virostko, John; Greiner, Dale L; Powers, Alvin C; Liu, Guozheng

    2015-01-01

    Synthetic DNA analogues with improved stability are widely used in life science. The 3'and/or 5' equivalent terminuses are often derivatized by attaching an active group for further modification, but a certain amount of non-derivatized impurity often remains. It is important to know to what extent the impurity would influence further modification. The reaction of an NHS ester with primary amine is one of the most widely used options to modify DNA analogues. In this short communication, a 3'-(NH2-biotin)-derivatized morpholino DNA analogue (MORF) was utilized as the model derivatized DNA analogue. Inclusion of a biotin concomitant with the primary amine at the 3'-terminus allows for the use of streptavidin to discriminate between the products from the derivatized MORF and non-derivatized MORF impurity. To detect the MORF reaction with NHS ester, S-acetyl NHS-MAG3 was conjugated to the DNA analogue for labeling with (99m)Tc, a widely used nuclide in the clinic. It was found that the non-derivatized MORF also reacted with the S-acetyl NHS-MAG3. Radiolabeling of the product yielded an equally high labeling efficiency. Nevertheless, streptavidin binding indicated that under the conditions of this investigation, the non-derivatized MORF was five times less reactive than the amine-derivatized MORF. PMID:25621701

  3. A FEASIBLE APPROACH TO EVALUATE THE RELATIVE REACTIVITY OF NHS-ESTER ACTIVATED GROUP WITH PRIMARY AMINE-DERIVATIZED DNA ANALOGUE AND NON-DERIVATIZED IMPURITY

    PubMed Central

    Dou, Shuping; Virostko, John; Greiner, Dale L.; Powers, Alvin C.; Liu, Guozheng

    2015-01-01

    Synthetic DNA analogues with improved stability are widely used in life science. The 3′ and/or 5′ equivalent terminuses are often derivatized by attaching an active group for further modification, but a certain amount of non-derivatized impurity often remains. It is important to know to what extent the impurity would influence further modification. The reaction of an NHS ester with primary amine is one of the most widely used options to modify DNA analogues. In this short communication, a 3′-(NH2-biotin)-derivatized morpholino DNA analogue (MORF) was utilized as the model derivatized DNA analogue. Inclusion of a biotin concomitant with the primary amine at the 3′-terminus allows for the use of streptavidin to discriminate between the products from the derivatized MORF and non-derivatized MORF impurity. To detect the MORF reaction with NHS ester, S-acetyl NHS-MAG3 was conjugated to the DNA analogue for labeling with 99mTc, a widely used nuclide in the clinic. It was found that the non-derivatized MORF also reacted with the S-acetyl NHS-MAG3. Radiolabeling of the product yielded an equally high labeling efficiency. Nevertheless, streptavidin binding indicated that under the conditions of this investigation, the non-derivatized MORF was five times less reactive than the amine-derivatized MORF. PMID:25621701

  4. 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.

  5. Copper thiocyanate: polytypes, defects, impurities, and surfaces.

    PubMed

    Tsetseris, Leonidas

    2016-07-27

    Copper thiocyanate (CuSCN) is an established solid state dye in solar cells and has emerged as a key material for applications in transparent conductors and solution-processed thin film transistors. Here we report the results of density-functional theory calculations on several fundamental properties related to the performance of CuSCN in the above-mentioned systems. We describe the structural and electronic properties of CuSCN phases and show that the material is prone to polytypism. We also perform a systematic study on various defects and hydrogen impurities and determine their effect on the electronic properties of the host system, particularly with respect to doping. Finally, we show that non-polar surfaces have low formation energies, suggesting easy cleavage along certain directions. PMID:27248787

  6. Analysis of the effects of impurities in silicon

    NASA Technical Reports Server (NTRS)

    Wohlgemuth, J.; Giuliano, M. N.

    1980-01-01

    A solar cell fabrication and analysis program was conducted to determine the effects on the resultant solar cell efficiency of impurities intentionally incorporated into silicon. It was found that certain impurities such as titanium, tantalum, and vanadium were bad, even in very small concentrations. Cell performance appeared relatively tolerable to impurities such as copper, carbon, calcium, chromium, iron and nickel (in the concentration levels which were considered).

  7. 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.

  8. Silicon materials task of the low-cost solar array project. Phase 4: Effects of impurities and processing on silicon solar cells

    NASA Astrophysics Data System (ADS)

    Hopkins, R. H.; Hanes, M. H.; Davis, J. R.; Rohatgi, A.; Raichoudhury, P.; Mollenkopf, H. C.

    1981-01-01

    The results of the study form a basis for silicon producers, wafer manufacturers, and cell fabricators to develop appropriate cost-benefit relationships for the use of less pure, less costly solar grade silicon. Cr is highly mobile in silicon even at temperatures as low as 600 C. Contrasting with earlier data for Mo, Ti, and V, Cr concentrations vary from place to place in polycrystalline silicon wafers and the electrically-active Cr concentration in the polysilicon is more than an order of magnitude smaller than would be projected from single crystal impurity data. We hypothesize that Cr diffuses during ingot cooldown after growth, preferentially segregates to grain and becomes electrically deactivated. Accelerated aging data from Ni-contaminated silicon imply that no significant impurity-induced cell performance reduction should be expected over a twenty year device lifetime.

  9. Mineral impurities in coal combustion

    SciTech Connect

    Raask, E.

    1985-01-01

    This article discusses the many and varied problems associated with coal combustion and suggests remedial measures to assist in producing electrical energy from coal more efficiently. Contents include: influence of coal mineral matter on boiler design; mineral impurities in coal; quality of coal utilized in power stations; coal grinding, abrasive fuel minerals and plant wear; particulates silicate minerals in boiler flame; reactions of nonsilicate impurities in coal flame; creation, capture and coalescence of particulate ash in boiler flame; slag viscosity; sintering, fusion and slagging propensities of coal ashes, adhesion of ash deposit on boiler tubes and refractory materials; deposition mechanisms, rate measurements and the mode of formation of boiler deposits; thermal radiation and heat transfer properties of boiler deposits; measures to combat boiler fouling and slagging; some specific ash-related problems with US Coals; use of additives in coal fired boilers; high temperature corrosion in coal-fired plants; ash impaction erosion wear; low temeprature fouling and corrosion; comparison of ash-related problems in pulverized fuel and other coal-fired systems.

  10. Resolving unfinished business: relating process to outcome.

    PubMed

    Greenberg, Leslie S; Malcolm, Wanda

    2002-04-01

    This study related the process of the resolution of unfinished business with a significant other to therapeutic outcome in a population of 26 clients who suffered from various forms of interpersonal problems and childhood maltreatment. Clients were treated in emotion-focused, experiential therapy with gestalt empty-chair dialogues. Those clients who expressed previously unmet interpersonal needs to the significant other, and manifested a shift in their view of the other, had significantly better treatment outcomes. The presence of the specific process of resolution in the clients' empty-chair dialogues was also found to be a better predictor of outcome than the working alliance. Degree of emotional arousal was found to discriminate between resolvers and nonresolvers. PMID:11952199

  11. Donor impurity-related linear and nonlinear intraband optical absorption coefficients in quantum ring: effects of applied electric field and hydrostatic pressure.

    PubMed

    Barseghyan, Manuk G; Restrepo, Ricardo L; Mora-Ramos, Miguel E; Kirakosyan, Albert A; Duque, Carlos A

    2012-01-01

    : The linear and nonlinear intraband optical absorption coefficients in GaAs three-dimensional single quantum rings are investigated. Taking into account the combined effects of hydrostatic pressure and electric field, applied along the growth direction of the heterostructure, the energies of the ground and first excited states of a donor impurity have been found using the effective mass approximation and a variational method. The energies of these states are examined as functions of the dimensions of the structure, electric field, and hydrostatic pressure. We have also investigated the dependencies of the linear, nonlinear, and total optical absorption coefficients as a function of incident photon energy for several configurations of the system. It is found that the variation of distinct sizes of the structure leads to either a redshift and/or a blueshift of the resonant peaks of the intraband optical spectrum. In addition, we have found that the application of an electric field leads to a redshift, whereas the influence of hydrostatic pressure leads to a blueshift (in the case of on-ring-center donor impurity position) of the resonant peaks of the intraband optical spectrum. PMID:23021497

  12. Removal of polar impurities from diesel and jet fuel

    SciTech Connect

    Diaz, Z.; Miller, J.H.

    1990-04-03

    This patent describes a process for the removal of polar impurities in diesel or jet fuel. It comprises: treating the diesel or jet fuel with a non-ionic macroreticular cross-linked acrylic aliphatic ester resin to effect removal of the polar impurities.

  13. 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

  14. 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.

  15. Impurity effects of transverse Ising model with multi-impurity

    NASA Astrophysics Data System (ADS)

    Huang, Xuchu; Yang, Zhihua

    2015-02-01

    We study the transverse Ising spin model with multi-impurity under the exact solution. The influence mechanisms of the concentration, configuration, impurity-inducing-interaction are investigated through the deformation energy, long-range order and the specific heat. It reveals a way that the impurities have crucial effects on the magnetic order of the system, which can be used to scale the order-disorder transition. In particular, the change of the exchange coupling interaction or magnetic field can lead to the deviation of the phase point. Moreover, the impurity excitation cannot be neglected in thermodynamic properties even though the concentration is only a few percent.

  16. Anticipating Explanations in Relative Clause Processing

    PubMed Central

    Rohde, H.; Levy, R.; Kehler, A.

    2011-01-01

    We show that comprehenders’ expectations about upcoming discourse coherence relations influence the resolution of local structural ambiguity. We employ cases in which two clauses share both a syntactic relationship and a discourse relationship, and hence in which syntactic and discourse processing might be expected to interact. An off-line sentence-completion study and an on-line self-paced reading study examined readers’ expectations for high/low relative clause attachments following implicit-causality and non-implicit-causality verbs (John detests/babysits the children of the musician who…). In the off-line study, the widely reported low-attachment preference for English is observed in the non-implicit causality condition, but this preference gives way to more high attachments in the implicit causality condition in cases in which (i) the verb’s causally implicated referent occupies the high-attachment position and (ii) the relative clause provides an explanation for the event described by the matrix clause (e.g., …who are arrogant and rude). In the on-line study, a similar preference for high attachment emerges in the implicit causality context—crucially, before the occurrence of any linguistic evidence that the RC does in fact provide an explanation—whereas the low-attachment preference is consistent elsewhere. These findings constitute the first demonstration that expectations about ensuing discourse coherence relationships can elicit full reversals in syntactic attachment preferences, and that these discourse-level expectations can affect on-line disambiguation as rapidly as lexical and morphosyntactic cues. PMID:21216396

  17. Processing and post-processing issues related to polymer films

    NASA Astrophysics Data System (ADS)

    Mueller, Chad David

    1998-12-01

    In Chapter 1, the effect of heat sealing variables on seal strength of a linear low density polyethylene (LLDPE) was examined. Blown films were heat sealed for various times and temperatures so that the films ranged from partially to fully melted. A temperature of 115sp°C or higher was required to form a good seal and was related to the heterogeneous composition of the LLDPE studied. At 115sp°C, the lower molecular weight, more highly branched chains easily diffused across the interface. However, because these chains represented a small fraction of the crystallinity and the molecular weight was low, they contributed much less than the full peel strength. Conversely, chains with less branching represented the main fraction of crystallinity (anchors for tie chains) and the highest molecular weights (more entanglements). Only at temperatures where the higher molecular weight, less branched chains began to melt and diffuse across the interface could high peel strengths be achieved. In Chapter 2, a novel coextrusion process used to create microlayered hierarchically structured films is described. With this technology, two or three polymers can be multiplied into tens or thousands of alternating layers. This unique coextrusion process can be used to combine polymers of widely dissimilar solid state morphologies and properties into unique layered and gradient structures. In addition, the effect of the viscosity ratio of the component materials and the effect of the layer multiplier geometry on the layer structure and uniformity was investigated. In Chapter 3, the development of a breathable film produced by the microlayer process is described. Two systems were produced: one with poly(ethylene oxide) (PEO) and CaCOsb3-filled LLDPE and the other with PEO and CaCOsb3-filled polypropylene. The water vapor transport (WVT) behavior of these films was measured and related to the tortuousity of the path through the PEO and filled polyolefin domains. PEO is water soluble and has

  18. Impurity sources in TEXTOR

    NASA Astrophysics Data System (ADS)

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

    1987-02-01

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

  19. 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.

  20. Relating rock avalanche morphology to emplacement processes

    NASA Astrophysics Data System (ADS)

    Dufresne, Anja; Prager, Christoph; Bösmeier, Annette

    2015-04-01

    The morphology, structure and sedimentological characteristics of rock avalanche deposits reflect both internal emplacement processes and external influences, such as runout path characteristics. The latter is mainly predisposed by topography, substrate types, and hydrogeological conditions. Additionally, the geological setting at the source slope controls, e.g. the spatial distribution of accumulated lithologies and hence material property-related changes in morphology, or the maximum clast size and amount of fines of different lithological units. The Holocene Tschirgant rock avalanche (Tyrol, Austria) resulted from failure of an intensely deformed carbonate rock mass on the southeast face of a 2,370-m-high mountain ridge. The initially sliding rock mass rapidly fragmented as it moved towards the floor of the Inn River valley. Part of the 200-250 x 106 m3 (Patzelt 2012) rock avalanche debris collided with and moved around an opposing bedrock ridge and flowed into the Ötz valley, reaching up to 6.3 km from source. Where the Tschirgant rock avalanche spread freely it formed longitudinal ridges aligned along motion direction as well as smaller hummocks. Encountering high topography, it left runup ridges, fallback patterns (i.e. secondary collapse), and compressional morphology (successively elevated, transverse ridges). Further evidence for the mechanical landslide behaviour is given by large volumes of mobilized valley-fill sediments (polymict gravels and sands). These sediments indicate both shearing and compressional faulting within the rock avalanche mass (forming their own morphological units through, e.g. in situ bulldozing or as distinctly different hummocky terrain), but also indicate extension of the spreading landslide mass (i.e. intercalated/injected gravels encountered mainly in morphological depressions between hummocks). Further influences on its morphology are given by the different lithological units. E.g. the transition from massive dolomite

  1. Impurity transport through a strongly interacting bosonic quantum gas

    SciTech Connect

    Johnson, T. H.; Clark, S. R.; Bruderer, M.; Jaksch, D.

    2011-08-15

    Using near-exact numerical simulations, we study the propagation of an impurity through a one-dimensional Bose lattice gas for varying bosonic interaction strengths and filling factors at zero temperature. The impurity is coupled to the Bose gas and confined to a separate tilted lattice. The precise nature of the transport of the impurity is specific to the excitation spectrum of the Bose gas, which allows one to measure properties of the Bose gas nondestructively, in principle, by observing the impurity; here we focus on the spatial and momentum distributions of the impurity as well as its reduced density matrix. For instance, we show it is possible to determine whether the Bose gas is commensurately filled as well as the bandwidth and gap in its excitation spectrum. Moreover, we show that the impurity acts as a witness to the crossover of its environment from the weakly to the strongly interacting regime, i.e., from a superfluid to a Mott insulator or Tonks-Girardeau lattice gas, and the effects on the impurity in both of these strongly interacting regimes are clearly distinguishable. Finally, we find that the spatial coherence of the impurity is related to its propagation through the Bose gas.

  2. Light-absorbing impurities in Arctic snow

    NASA Astrophysics Data System (ADS)

    Doherty, S. J.; Warren, S. G.; Grenfell, T. C.; Clarke, A. D.; Brandt, R. E.

    2010-12-01

    Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983-1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean during 1998 and 2005-2009, on tundra, glaciers, ice caps, sea ice, frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack is accessible for sampling. Sampling was carried out in summer on the Greenland Ice Sheet and on the Arctic Ocean, of melting glacier snow and sea ice as well as cold snow. About 1200 snow samples have been analyzed for this study. The snow is melted and filtered; the filters are analyzed in a specially designed spectrophotometer system to infer the concentration of black carbon (BC), the fraction of absorption due to non-BC light-absorbing constituents and the absorption Ångstrom exponent of all particles. This is done using BC calibration standards having a mass absorption efficiency of 6.0 m2 g-1 at 550 nm and by making an assumption that the absorption Angstrom exponent for BC is 1.0 and for non-BC light-absorbing aerosol is 5.0. The reduction of snow albedo is primarily due to BC, but other impurities, principally brown (organic) carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. The meltwater from selected snow samples was saved for chemical analysis to identify sources of the impurities. Median BC amounts in surface snow are as follows (nanograms of carbon per gram of snow): Greenland 3, Arctic Ocean snow 7, melting sea ice 8, Arctic Canada 8, subarctic Canada 14

  3. Theoretical Study of Radiation from a Broad Range of Impurity Ions for Magnetic Fusion Diagnostics

    SciTech Connect

    Safronova, Alla

    2014-03-14

    Spectroscopy of radiation emitted by impurities plays an important role in the study of magnetically confined fusion plasmas. The measurements of these impurities are crucial for the control of the general machine conditions, for the monitoring of the impurity levels, and for the detection of various possible fault conditions. Low-Z impurities, typically present in concentrations of 1%, are lithium, beryllium, boron, carbon, and oxygen. Some of the common medium-Z impurities are metals such as iron, nickel, and copper, and high-Z impurities, such as tungsten, are present in smaller concentrations of 0.1% or less. Despite the relatively small concentration numbers, the aforementioned impurities might make a substantial contribution to radiated power, and also influence both plasma conditions and instruments. A detailed theoretical study of line radiation from impurities that covers a very broad spectral range from less than 1 Å to more than 1000 Å has been accomplished and the results were applied to the LLNL Electron Beam Ion Trap (EBIT) and the Sustained Spheromak Physics Experiment (SSPX) and to the National Spherical Torus Experiment (NSTX) at Princeton. Though low- and medium-Z impurities were also studied, the main emphasis was made on the comprehensive theoretical study of radiation from tungsten using different state-of-the-art atomic structure codes such as Relativistic Many-Body Perturbation Theory (RMBPT). The important component of this research was a comparison of the results from the RMBPT code with other codes such as the Multiconfigurational Hartree–Fock developed by Cowan (COWAN code) and the Multiconfiguration Relativistic Hebrew University Lawrence Atomic Code (HULLAC code), and estimation of accuracy of calculations. We also have studied dielectronic recombination, an important recombination process for fusion plasma, for variety of highly and low charged tungsten ions using COWAN and HULLAC codes. Accurate DR rate coefficients are needed for

  4. Is Visual Information Processing Related to Reading?

    ERIC Educational Resources Information Center

    Palmer, John C.; And Others

    A large stratified sample of university undergraduate students differing in reading ability performed a diverse set of psychometric and information processing tasks in a study exploring the role of visual information processing skill as a component in reading ability. Using a correlation analysis of individual differences, the interrelationships…

  5. Processing Relative Clauses in Supportive Contexts

    ERIC Educational Resources Information Center

    Fedorenko, Evelina; Piantadosi, Steve; Gibson, Edward

    2012-01-01

    Results from two self-paced reading experiments in English are reported in which subject- and object-extracted relative clauses (SRCs and ORCs, respectively) were presented in contexts that support both types of relative clauses (RCs). Object-extracted versions were read more slowly than subject-extracted versions across both experiments. These…

  6. Disruption of Relational Processing Underlies Poor Memory for Order

    ERIC Educational Resources Information Center

    Jonker, Tanya R.; MacLeod, Colin M.

    2015-01-01

    McDaniel and Bugg (2008) proposed that relatively uncommon stimuli and encoding tasks encourage elaborative encoding of individual items (item-specific processing), whereas relatively typical or common encoding tasks encourage encoding of associations among list items (relational processing). It is this relational processing that is thought to…

  7. Non-Debye relaxation in the dielectric response of nematic liquid crystals: Surface and memory effects in the adsorption-desorption process of ionic impurities

    NASA Astrophysics Data System (ADS)

    de Paula, J. L.; Santoro, P. A.; Zola, R. S.; Lenzi, E. K.; Evangelista, L. R.; Ciuchi, F.; Mazzulla, A.; Scaramuzza, N.

    2012-11-01

    We demonstrate theoretically that the presence of ions in insulating materials such as nematic liquid crystals may be responsible for the dielectric spectroscopy behavior observed experimentally. It is shown that, at low frequencies, an essentially non-Debye relaxation process takes place due to surface effects. This is accomplished by investigating the effects of the adsorption-desorption process on the electrical response of an electrolytic cell when the generation and recombination of ions is present. The adsorption-desorption is governed by a non-usual kinetic equation in order to incorporate memory effects related to a non-Debye relaxation and the roughness of the surface. The analysis is carried out by searching for solutions to the drift-diffusion equation that satisfy the Poisson equation relating the effective electric field to the net charge density. We also discuss the effect of the mobility of the ions, i.e., situations with equal and different diffusion coefficients for positive and negative ions, on the impedance and obtain an exact expression for the admittance. The model is compared with experimental results measured for the impedance of a nematic liquid crystal sample and a very good agreement is obtained.

  8. 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.

  9. Influence of grain boundary silica impurity on alumina toughness

    SciTech Connect

    Moya, J.S.; Kriven, W.M.; Pask, J.A.

    1980-08-01

    In a series of previous reports the effect of silica impurity on aggregation state and on electropheretic, pressing, filtering and sintering behavior on alumina powders was presented. The results obtained showed that the silica surface impurity plays an important role in the ceramic processing of powders by (a) decreasing the pH values of the isoelectric point (i.e.p.), which affects the aggregation state of the powder, and (b) decreasing the compactability and the activation energy for the initial stage of sintering. In the phase of the studies emphasis was given to the effect of the presence of silica impurity on the toughness and fracture behavior of alumina samples.

  10. 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.

  11. Precipitation of impurities in 9-32-0 grade fluid fertilizers

    SciTech Connect

    Dillard, E.F.; Scheib, R.M.; Greenwell, B.E.

    1986-01-01

    For several years TVA has been studying production of 9-32-0 ammonium polyphosphate suspension produced from ammoniated merchant-grade wet-process orthophosphoric acid. Suspensions containing polyphosphate have an advantage over those that contain only orthophosphate in that they can be stored satisfactorily at much lower temperature. However, the introduction of polyphosphate (pyrophosphate anion) complicates the precipitation of impurities and has yielded inconsistent storage characteristics in 9-32-0 fluid fertilizers. Fluorine also has been shown to affect suspension fertilizer properties. The viscosity of 13-38-0 orthophosphate suspension fertilizers is affected by the atomic ratios F:(Al + Fe + Mg). Addition of fluorine prevents sludges and precipitates in ammonium polyphosphate fertilizer solutions - the proper amount of fluorine is related to the amount of each of the metallic impurities present and also to the fraction of the phosphate present as pyrophosphate. Incorporation of polyphosphate or fluorine or both has been shown to have positive effects on ammoniated wet-process phosphoric acid (WPPA), but they do not report the solubility relationships of the cation impurities (Fe, Al, Mg, and Ca) with respect to the anion constituents (PO/sub 4/, P/sub 2/O/sub 7/, and F). Therefore, a factorial study was developed to determine the solubility relationships of the precipitated metal impurities encountered in 9-32-0 fluid fertilizers. 10 refs., 1 fig., 20 tabs.

  12. Impurity Effects on Momentum Transport and Residual Stress

    NASA Astrophysics Data System (ADS)

    Ko, Sehoon; Jhang, Hogun; Singh, R.

    2015-11-01

    Impurities are inevitable during tokamak plasma operation because of strong interaction of plasma and plasma facing component and helium ash as a byproduct of fusion process. They cause problems such as radiation power loss and fusion fuel dilution. On the other hands, they are used to diagnosis plasma parameters (CES, XICS etc) and to suppress edge-localized mode by wall-coating. In this research, 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.

  13. Localized states of a semi-infinite zigzag graphene sheet with impurity lines

    SciTech Connect

    Cunha, A. M. C.; Ahmed, Maher Z.; Cottam, M. G.; Filho, R. N. Costa

    2014-07-07

    The localized states of a semi-infinite zigzag graphene sheet are studied using a tight-binding model that allows for the inclusion of either one or two lines of impurities. These impurity lines of atoms are placed in rows labeled as n (n=1, 2, 3, …), where n=1 is the free edge. The localized defect modes associated with these impurities are studied analytically and numerically within a tridiagonal matrix formalism. For one impurity line, the modes are analyzed according to the position of that line on the sheet, whereas the modes for two impurities are studied also according to their separation and their positions relative to the edge. When an impurity line is located at the edge (n=1), it is found that the edge states are modified. When the impurities are positioned away from an edge (n>1), additional localized modes are found to occur that may be relatively flat in their dispersion.

  14. Thermodynamic Uncertainty Relation for Biomolecular Processes

    NASA Astrophysics Data System (ADS)

    Barato, Andre C.; Seifert, Udo

    2015-04-01

    Biomolecular systems like molecular motors or pumps, transcription and translation machinery, and other enzymatic reactions, can be described as Markov processes on a suitable network. We show quite generally that, in a steady state, the dispersion of observables, like the number of consumed or produced molecules or the number of steps of a motor, is constrained by the thermodynamic cost of generating it. An uncertainty ɛ requires at least a cost of 2 kBT /ɛ2 independent of the time required to generate the output.

  15. 12 CFR 618.8010 - Related services authorization process.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Related services authorization process. 618... PROVISIONS Related Services § 618.8010 Related services authorization process. (a) Authorities. System banks... to review and evaluation during the examination and enforcement process. (2) The FCA shall...

  16. Public relations and the radiation processing industry

    NASA Astrophysics Data System (ADS)

    Coates, T. Donna

    The world's uneasiness and mistrust regarding anything nuclear has heightened in recent years due to events such as Chernobyl and Three Mile Island. Opinion polls and attitude surveys document the public's growing concern about issues such as the depletion of the ozone layer, the resulting greenhouse effect and exposure of our planet to cosmic radiation. Ultimately, such research reveals an underlying fear regarding the unseen impacts of modern technology on the environment and on human health. These concerns have obvious implications for the radiation processing industry, whose technology is nuclear based and not easily understood by the public. We have already seen organized nuclear opponents mobilize public anxiety, fear and misunderstanding in order to oppose the installation of radiation processing facilities and applications such as food irradiation. These opponents will no doubt try to strengthen resistance to our technology in the future. Opponents will attempt to convince the public that the risks to public and personal health and safety outweigh the benefits of our technology. We in the industry must head off any tendency for the public to see us as the "enemy". Our challenge is to counter public uneasiness and misunderstanding by effectively communicating the human benefits of our technology. Clearly it is a challenge we cannot afford to ignore.

  17. 12 CFR 618.8010 - Related services authorization process.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 6 2011-01-01 2011-01-01 false Related services authorization process. 618.8010 Section 618.8010 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM GENERAL PROVISIONS Related Services § 618.8010 Related services authorization process. (a) Authorities. System banks and associations may only offer related...

  18. Characterization of PMR polyimides: Correlation of ester impurities with composite properties

    NASA Technical Reports Server (NTRS)

    Lauver, R. W.; Vannucci, R. D.

    1979-01-01

    The presumed relationship of chemical impurities to final composite properties was investigated for PMR-polyimide resin. Ester/acid solutions of one monomer were aged at selected temperatures and chemical changes were monitored spectroscopically. At selected intervals, graphite fiber reinforced composite panels were fabricated. Changes in resin processing characteristics and composite properties were determined. The correlation of these data are discussed as are related characterization studies of PMR-polyimide resin.

  19. Characterization of PMR polyimides - Correlation of ester impurities with composite properties

    NASA Technical Reports Server (NTRS)

    Lauver, R. W.; Vannucci, R. D.

    1979-01-01

    The presumed relationship of chemical impurities to final composite properties is the rationale for most chemical characterization studies. This study examines this relationship for PMR-polyimide resin. Ester/acid solutions of one monomer were aged at selected temperatures and chemical changes were monitored spectroscopically. At selected intervals, graphite fiber reinforced composite panels were fabricated. Changes in resin processing characteristics and composite properties were determined. The correlation of these data are discussed as are related characterization studies of PMR-polyimide resin.

  20. The influence of finite impurity size on heterogeneous nucleation

    NASA Technical Reports Server (NTRS)

    Weinberg, Michael C.

    1992-01-01

    The effects of the finite size of impurities upon the heterogeneous nucleation rate is examined. Simple arguments based upon probability theory are used to find the relative nucleation rate, p(j), on particles containing j nuclei. The expression for p(j) is used in turn to compute the overall nucleation rate and average number of nuclei on an impurity as a function of time.

  1. 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.

  2. 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

  3. The effects of the electric and intense laser field on the binding energies of donor impurity states (1s and 2p±) and optical absorption between the related states in an asymmetric parabolic quantum well

    NASA Astrophysics Data System (ADS)

    Kasapoglu, E.; Sakiroglu, S.; Sökmen, I.; Restrepo, R. L.; Mora-Ramos, M. E.; Duque, C. A.

    2016-10-01

    We have calculated the effects of electric and intense laser fields on the binding energies of the ground and some excited states of conduction electrons coupled to shallow donor impurities as well as the total optical absorption coefficient for transitions between 1s and 2p± electron-impurity states in a asymmetric parabolic GaAs/Ga1-x AlxAs quantum well. The binding energies were obtained using the effective-mass approximation within a variational scheme. Total absorption coefficient (linear and nonlinear absorption coefficient) for the transitions between any two impurity states were calculated from first- and third-order dielectric susceptibilities derived within a perturbation expansion for the density matrix formalism. Our results show that the effects of the electric field, intense laser field, and the impurity location on the binding energy of 1s-impurity state are more pronounced compared with other impurity states. If the well center is changed to be Lc<0 (Lc>0), the effective well width decreases (increases), and thus we can obtain the red or blue shift in the resonant peak position of the absorption coefficient by changing the intensities of the electric and non-resonant intense laser field as well as dimensions of the well and impurity positions.

  4. Analytical Dependence of the Ignition Dynamics Parameters on the Low-Z Impurity Concentration

    NASA Astrophysics Data System (ADS)

    Mahdavi, Mohammad; Abedi, Sayed Ebrahim

    2014-12-01

    In this paper, thermonuclear burning of the deuterium-tritium (D/T) plasma of an inertial confinement fusion (ICF) target is studied in the presence of low-Z impurities (lithium, beryllium, and carbon) with arbitrary concentrations. The effect of impurities produced due to the mixing of the thermonuclear fuel with the material of the structural elements of the target during its compression on the process of target burning is studied. Also, the effect of impurity concentration on the plasma ignition parameters such as ignition temperature, confinement parameter ρR, and ignition energy are discussed. The models are constructed for an isobaric and an isochoric plasma for the case in which the burning is initiated in the central heated region of the target and then propagated into the surrounding relatively cold fuel. In ICF spherical implosions of the D/T fuel, the ignition parameters as ignition temperature and parameter ρR in the hot spot are approximately 7 - 10 keV and 0.2 - 0.4 g cm-2 respectively, and these values are increased by the presence of impurities.

  5. Force on a slow moving impurity due to thermal and quantum fluctuations in a 1D Bose-Einstein condensate

    SciTech Connect

    Roberts, David; Sykes, Andrew

    2009-01-01

    We study the drag force acting on an impurity moving through a 1D Bose-Einstein condensate in the presence of both quantum and thermal fluctuations. We are able to find exact analytical solutions of the partial differential equations to the level of the Bogoliubov approximation. At zero temperature, we find a nonzero force is exerted on the impurity at subcritical velocities, due to the scattering of quantum fluctuations. We make the following explicit assumptions: far from the impurity the system is in a quantum state given by that of a zero (or finite) temperature Bose-Einstein condensate, and the scattering process generates only causally related reflection/transmission. The results raise unanswered questions in the quantum dynamics associated with the formation of persistent currents.

  6. Impurity-assisted tunneling magnetoresistance under a weak magnetic field.

    PubMed

    Txoperena, Oihana; Song, Yang; Qing, Lan; Gobbi, Marco; Hueso, Luis E; Dery, Hanan; Casanova, Fèlix

    2014-10-01

    Injection of spins into semiconductors is essential for the integration of the spin functionality into conventional electronics. Insulating layers are often inserted between ferromagnetic metals and semiconductors for obtaining an efficient spin injection, and it is therefore crucial to distinguish between signatures of electrical spin injection and impurity-driven effects in the tunnel barrier. Here we demonstrate an impurity-assisted tunneling magnetoresistance effect in nonmagnetic-insulator-nonmagnetic and ferromagnetic-insulator-nonmagnetic tunnel barriers. In both cases, the effect reflects on-off switching of the tunneling current through impurity channels by the external magnetic field. The reported effect is universal for any impurity-assisted tunneling process and provides an alternative interpretation to a widely used technique that employs the same ferromagnetic electrode to inject and detect spin accumulation. PMID:25325651

  7. 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.

  8. Classical impurities and boundary Majorana zero modes in quantum chains

    NASA Astrophysics Data System (ADS)

    Müller, Markus; Nersesyan, Alexander A.

    2016-09-01

    We study the response of classical impurities in quantum Ising chains. The Z2 degeneracy they entail renders the existence of two decoupled Majorana modes at zero energy, an exact property of a finite system at arbitrary values of its bulk parameters. We trace the evolution of these modes across the transition from the disordered phase to the ordered one and analyze the concomitant qualitative changes of local magnetic properties of an isolated impurity. In the disordered phase, the two ground states differ only close to the impurity, and they are related by the action of an explicitly constructed quasi-local operator. In this phase the local transverse spin susceptibility follows a Curie law. The critical response of a boundary impurity is logarithmically divergent and maps to the two-channel Kondo problem, while it saturates for critical bulk impurities, as well as in the ordered phase. The results for the Ising chain translate to the related problem of a resonant level coupled to a 1d p-wave superconductor or a Peierls chain, whereby the magnetic order is mapped to topological order. We find that the topological phase always exhibits a continuous impurity response to local fields as a result of the level repulsion of local levels from the boundary Majorana zero mode. In contrast, the disordered phase generically features a discontinuous magnetization or charging response. This difference constitutes a general thermodynamic fingerprint of topological order in phases with a bulk gap.

  9. Slowing Down: Age-Related Neurobiological Predictors of Processing Speed

    PubMed Central

    Eckert, Mark A.

    2011-01-01

    Processing speed, or the rate at which tasks can be performed, is a robust predictor of age-related cognitive decline and an indicator of independence among older adults. This review examines evidence for neurobiological predictors of age-related changes in processing speed, which is guided in part by our source based morphometry findings that unique patterns of frontal and cerebellar gray matter predict age-related variation in processing speed. These results, together with the extant literature on morphological predictors of age-related changes in processing speed, suggest that specific neural systems undergo declines and as a result slow processing speed. Future studies of processing speed – dependent neural systems will be important for identifying the etiologies for processing speed change and the development of interventions that mitigate gradual age-related declines in cognitive functioning and enhance healthy cognitive aging. PMID:21441995

  10. Simultaneous separation and determination of process-related substances and degradation products of venlafaxine by reversed-phase HPLC.

    PubMed

    Nageswara Rao, R; Narasa Raju, A

    2006-12-01

    A simple and rapid gradient RP HPLC method for simultaneous separation and determination of venlafaxine and its related substances in bulk drugs and pharmaceutical formulations has been developed. As many as four process impurities and one degradation product of venlafaxine have been separated on a Kromasil KR100-5C18 (4.6 mm x 250 mm; particle size 5 microm) column with gradient elution using 0.3% diethylamine buffer (pH 3.0) and ACN/methanol (90:10 v/v) as a mobile phase. The column was maintained at 40 degrees C and the eluents were monitored with photo diode array detection at 225 nm. The chromatographic behaviour of all the compounds was examined under variable compositions of different solvents, temperatures, buffer concentrations and pH. The method was validated in terms of accuracy, precision and linearity as per ICH guidelines. The inter- and intraday assay precision was < 4.02% (%RSD) and the recoveries were in the range of 96.19-101.14% with %RSD < 1.15%. The correlation coefficients (r2) for calibration curves of venlafaxine as well as impurities were in the range of 0.9942-0.9999. The proposed RP-LC method was successfully applied to the analysis of commercial formulations and the recoveries of venlafaxine were in the range of 99.32-100.67 with %RSD <0.58%. The method could be of use not only for rapid and routine evaluation of the quality of venlafaxine in bulk drug manufacturing units but also for the detection of its impurities in pharmaceutical formulations. Forced degradation of venlafaxine was carried out under thermal, photo, acidic, basic and peroxide conditions and the acid degradation products were characterized by ESI-MS/MS, 1H NMR and FT-IR spectral data.

  11. Transverse Ising model with multi-impurity

    NASA Astrophysics Data System (ADS)

    Huang, Xuchu; Yang, Zhihua

    2015-05-01

    We study the transverse Ising spin model with spin-1 impurities under the exact solution. We develop a universal method to deal with the multi-impurity problem by introducing a displacement quantity in the wave function and get a recursive formula to simplify the calculation of the partition function. This allows us to rigorously determine the impurity effects for a specific distribution of impurity in the thermodynamic limit. The low temperature behaviors are governed by the interplay between host and impurity excitations, and the quantum critical fluctuations around the critical point of the transverse Ising model are tuned by the transverse field and the concentration of impurity. However the impurity effects are limited, which depends on the host-impurity exchange interaction and the coupling strength of impurities.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Effects of Zr impurity on microscopic behavior of Hf metal

    NASA Astrophysics Data System (ADS)

    Dey, S. K.; Dey, C. C.; Saha, S.

    2016-08-01

    Hf metal with ∼ 3 wt% Zr impurity has been reinvestigated by perturbed angular correlation (PAC) spectroscopy using a LaBr3(Ce)-BaF2 detector set up to understand the microscopic behavior of this metal with temperature. From present measurements, five quadrupole interaction frequencies have been found at room temperature where both pure hcp fraction (∼33%) with 12 nearest neighbor Hf surrounding the probe 181Hf atom and the probe-impurity fraction (∼33%) corresponding to 11 nearest neighbor Hf plus one dissimilar Zr atom are clearly distinguished. At room temperature, the results for quadrupole frequency and asymmetry parameter are found to be ωQ=51.6(4) Mrad/s, η=0.20(4) for the impurity fraction and ωQ=46.8(2) Mrad/s, η=0 for the pure fraction with values of frequency distribution width δ=0 for both components. At 77 K, only 1 NN Zr impurity (∼93%) and pure hcp (∼7%) components have been found with a value of δ ∼ 10% for the impurity fraction. A drastic change in microstructural configuration of Hf metal is observed at 473 K where the impurity fraction increases to ∼ 50% and the pure hcp fraction reduces to ∼ 15% with abrupt changes in quadrupole frequencies for both components. The pure fraction then increases with temperature and enhances to ∼50% at 973 K. In the temperature range 473-973 K, quadrupole frequencies for both components are found to decrease slowly with temperature. Using the Arrhenius relation, binding energy (B) for the probe-impurity pair and the entropy of formation are measured from temperature dependent fractions of probe-impurity and pure hcp in the temperature range 473-773 K. The three other minor components found at different temperatures are attributed to crystalline defects.

  17. Processing Relative Clauses by Hungarian Typically Developing Children

    ERIC Educational Resources Information Center

    Kas, Bence; Lukacs, Agnes

    2012-01-01

    Hungarian is a language with morphological case marking and relatively free word order. These typological characteristics make it a good ground for testing the crosslinguistic validity of theories on processing sentences with relative clauses. Our study focused on effects of structural factors and processing capacity. We tested 43 typically…

  18. Attentional Processes in Children's Overt and Relational Aggression

    ERIC Educational Resources Information Center

    Arsenault, Darin J.; Foster, Sharon L.

    2012-01-01

    This study examined attention and memory processes assumed by the social information-processing model to be biased in aggressive children. We also explored whether similar biases were associated with overt and relational aggression. A total of 96 fourth through sixth graders saw videos of overtly and relationally aggressive child actors and…

  19. Relative Clause Processing in Mandarin: Evidence from the Maze Task

    ERIC Educational Resources Information Center

    Qiao, Xiaomei; Shen, Liyao; Forster, Kenneth

    2012-01-01

    Contradictory results have been found in Chinese as to whether subject relative clauses are easier to process than object relative clauses. One major disagreement concerns the region where the difficulty arises. In this study, a "maze" task was used to localise processing difficulty by requiring participants to make a choice between two…

  20. 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.

  1. 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.

  2. Density of states in gapped superconductors with pairing-potential impurities

    NASA Astrophysics Data System (ADS)

    Bespalov, Anton; Houzet, Manuel; Meyer, Julia S.; Nazarov, Yuli V.

    2016-03-01

    We study the density of states in disordered s -wave superconductors with a small gap anisotropy. We consider disorder in the form of common nonmagnetic scatterers and pairing-potential impurities, which interact with electrons via an electric potential and a local distortion of the superconducting gap. Using quasiclassical Green functions, we determine the bound-state spectrum at a single impurity and the density of states at a finite concentration of impurities. We show that, if the gap is isotropic, an isolated impurity with suppressed pairing supports an infinite number of Andreev states. With growing impurity concentration, the energy-dependent density of states evolves from a sharp gap edge with an impurity band below it to a smeared BCS singularity in the so-called universal limit. Within one spin sector, pairing-potential impurities and weak spin-polarized magnetic impurities have essentially the same effect on the density of states. We note that, if a gap anisotropy is present, the density of states becomes sensitive to ordinary potential disorder, and the existence of Andreev states localized at pairing-potential impurities requires special conditions. An unusual feature related to the anisotropy is a nonmonotonic dependence of the gap edge smearing on impurity concentration.

  3. The Effects of Impurities on Protein Crystal Growth and Nucleation: A Preliminary Study

    NASA Technical Reports Server (NTRS)

    Schall, Constance A.

    1998-01-01

    Kubota and Mullin (1995) devised a simple model to account for the effects of impurities on crystal growth of small inorganic and organic molecules in aqueous solutions. Experimentally, the relative step velocity and crystal growth of these molecules asymptotically approach zero or non-zero values with increasing concentrations of impurities. Alternatively, the step velocity and crystal growth can linearly approach zero as the impurity concentration increases. The Kubota-Mullin model assumes that the impurity exhibits Langmuirian adsorption onto the crystal surface. Decreases in step velocities and subsequent growth rates are related to the fractional coverage (theta) of the crystal surface by adsorbed impurities; theta = Kx / (I +Kx), x = mole fraction of impurity in solution. In the presence of impurities, the relative step velocity, V/Vo, and the relative growth rate of a crystal face, G/Go, are proposed to conform to the following equations: V/Vo approx. = G/Go = 1 - (alpha)(theta). The adsorption of impurity is assumed to be rapid and in quasi-equilibrium with the crystal surface sites available. When the value of alpha, an effectiveness factor, is one the growth will asymptotically approach zero with increasing concentrations of impurity. At values less than one, growth approaches a non-zero value asymptotically. When alpha is much greater than one, there will be a linear relationship between impurity concentration and growth rates. Kubota and Mullin expect alpha to decrease with increasing supersaturation and shrinking size of a two dimensional nucleus. It is expected that impurity effects on protein crystal growth will exhibit behavior similar to that of impurities in small molecule growth. A number of proteins were added to purified chicken egg white lysozyme, the effect on crystal nucleation and growth assessed.

  4. Prelinguistic Relational Concepts: Investigating Analogical Processing in Infants

    ERIC Educational Resources Information Center

    Ferry, Alissa L.; Hespos, Susan J.; Gentner, Dedre

    2015-01-01

    This research asks whether analogical processing ability is present in human infants, using the simplest and most basic relation--the "same-different" relation. Experiment 1 (N = 26) tested whether 7- and 9-month-olds spontaneously detect and generalize these relations from a single example, as previous research has suggested. The…

  5. PROCESS FOR THE RECOVERY OF URANIUM

    DOEpatents

    Morris, G.O.

    1955-06-21

    This patent relates to a process for the recovery of uranium from impure uranium tetrafluoride. The process consists essentially of the steps of dissolving the impure uranium tetrafluoride in excess dilute sulfuric acid in the presence of excess hydrogen peroxide, precipitating ammonium uranate from the solution so formed by adding an excess of aqueous ammonia, dissolving the precipitate in sulfuric acid and adding hydrogen peroxide to precipitate uranium peroxdde.

  6. Impurity gettering in silicon using cavities formed by helium implantation and annealing

    DOEpatents

    Myers, S.M. Jr.; Bishop, D.M.; Follstaedt, D.M.

    1998-11-24

    Impurity gettering in silicon wafers is achieved by a new process consisting of helium ion implantation followed by annealing. This treatment creates cavities whose internal surfaces are highly chemically reactive due to the presence of numerous silicon dangling bonds. For two representative transition-metal impurities, copper and nickel, the binding energies at cavities were demonstrated to be larger than the binding energies in precipitates of metal silicide, which constitutes the basis of most current impurity gettering. As a result the residual concentration of such impurities after cavity gettering is smaller by several orders of magnitude than after precipitation gettering. Additionally, cavity gettering is effective regardless of the starting impurity concentration in the wafer, whereas precipitation gettering ceases when the impurity concentration reaches a characteristic solubility determined by the equilibrium phase diagram of the silicon-metal system. The strong cavity gettering was shown to induce dissolution of metal-silicide particles from the opposite side of a wafer. 4 figs.

  7. Impurity gettering in silicon using cavities formed by helium implantation and annealing

    DOEpatents

    Myers, Jr., Samuel M.; Bishop, Dawn M.; Follstaedt, David M.

    1998-01-01

    Impurity gettering in silicon wafers is achieved by a new process consisting of helium ion implantation followed by annealing. This treatment creates cavities whose internal surfaces are highly chemically reactive due to the presence of numerous silicon dangling bonds. For two representative transition-metal impurities, copper and nickel, the binding energies at cavities were demonstrated to be larger than the binding energies in precipitates of metal silicide, which constitutes the basis of most current impurity gettering. As a result the residual concentration of such impurities after cavity gettering is smaller by several orders of magnitude than after precipitation gettering. Additionally, cavity gettering is effective regardless of the starting impurity concentration in the wafer, whereas precipitation gettering ceases when the impurity concentration reaches a characteristic solubility determined by the equilibrium phase diagram of the silicon-metal system. The strong cavity gettering was shown to induce dissolution of metal-silicide particles from the opposite side of a wafer.

  8. 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.

  9. Rapid separation and determination of process-related substances of paracetamol using reversed-phase HPLC with photo diode array as a detector.

    PubMed

    Rao, R Nageswara; Narasaraju, A

    2006-02-01

    A simple and rapid gradient reversed-phase high-performance liquid chromatographic method for simultaneous separation and determination of paracetamol and its related compounds in bulk drugs and pharmaceutical formulations has been developed. As many as nine process impurities and one degradation product of paracetamol have been separated on a Symmetry C18 column (4.6 x 250 mm i.d., particle size 5 microm) with gradient elution using 0.01 M potassium dihydrogen phosphate buffer (pH 3.0) and acetonitrile as mobile phase and photo diode array detection at 215 nm. The chromatographic behavior of all the compounds was examined under variable compositions of different solvents, temperatures, buffer concentrations and pH values. The correlation coefficients for calibration curves for paracetamol as well as impurities were in the range of 0.9951 - 0.9994. The proposed RP-LC method was successfully applied to the analysis of commercial formulations; the recoveries of paracetamol were in the range of 99-101%. The method could be of use not only for rapid and routine evaluation of the quality of paracetamol in bulk drug manufacturing units but also for detection of its impurities in pharmaceutical formulations.

  10. 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.

  11. Polymeric efficiency in remove impurities during cottonseed biodiesel production

    NASA Astrophysics Data System (ADS)

    Lin, H. L.; Liang, Y. H.; Yan, J.; Lin, H. D.; Espinosa, A. R.

    2016-07-01

    This paper describes a new process for developing biodiesel by polymer from crude cottonseed oil. The study was conducted to examine the effectiveness of the alkali transesterification-flocculation-sedimentation process on fast glycerol and other impurities in the separation from biodiesel by using quaternary polyamine-based cationic polymers SL2700 and polyacylamide cationic polymer SAL1100. The settling velocity of glycerol and other impurities in biodiesel was investigated through settling test experiments; the quality of the biodiesel was investigated by evaluating the viscosity and density. The results revealed that SL2700, SAL1100 and their combination dramatically improved the settling velocity of glycerol and other impurities materials than traditional method. SL 2700 with molecular weight of 0.2 million Da and charge density of 50% then plus SAL1100 with molecular weight of 11 million Da and charge density of 10% induced observable particle aggregation with the best settling performance.

  12. Impurity flows and plateau-regime poloidal density variation in a tokamak pedestal

    SciTech Connect

    Landreman, M.; Fueloep, T.; Guszejnov, D.

    2011-09-15

    In the pedestal of a tokamak, the sharp radial gradients of density and temperature can give rise to poloidal variation in the density of impurities. At the same time, the flow of the impurity species is modified relative to the conventional neoclassical result. In this paper, these changes to the density and flow of a collisional impurity species are calculated for the case when the main ions are in the plateau regime. In this regime, it is found that the impurity density can be higher at either the inboard or outboard side. This finding differs from earlier results for banana- or Pfirsch-Schlueter-regime main ions, in which case the impurity density is always higher at the inboard side in the absence of rotation. Finally, the modifications to the impurity flow are also given for the other regimes of main-ion collisionality.

  13. Greater efficiency in attentional processing related to mindfulness meditation.

    PubMed

    van den Hurk, Paul A M; Giommi, Fabio; Gielen, Stan C; Speckens, Anne E M; Barendregt, Henk P

    2010-06-01

    In this study, attentional processing in relation to mindfulness meditation was investigated. Since recent studies have suggested that mindfulness meditation may induce improvements in attentional processing, we have tested 20 expert mindfulness meditators in the attention network test. Their performance was compared to that of 20 age- and gender-matched controls. In addition to attentional network analyses, overall attentional processing was analysed by means of efficiency scores (i.e., accuracy controlled for reaction time). Better orienting and executive attention (reflected by smaller differences in either reaction time or error score, respectively) were observed in the mindfulness meditation group. Furthermore, extensive mindfulness meditation appeared to be related to a reduction of the fraction of errors for responses with the same reaction time. These results provide new insights into differences in attentional processing related to mindfulness meditation and suggest the possibility of increasing the efficiency in attentional processing by extensive mental training.

  14. Dynamic Neural Processing of Linguistic Cues Related to Death

    PubMed Central

    Ma, Yina; Qin, Jungang; Han, Shihui

    2013-01-01

    Behavioral studies suggest that humans evolve the capacity to cope with anxiety induced by the awareness of death’s inevitability. However, the neurocognitive processes that underlie online death-related thoughts remain unclear. Our recent functional MRI study found that the processing of linguistic cues related to death was characterized by decreased neural activity in human insular cortex. The current study further investigated the time course of neural processing of death-related linguistic cues. We recorded event-related potentials (ERP) to death-related, life-related, negative-valence, and neutral-valence words in a modified Stroop task that required color naming of words. We found that the amplitude of an early frontal/central negativity at 84–120 ms (N1) decreased to death-related words but increased to life-related words relative to neutral-valence words. The N1 effect associated with death-related and life-related words was correlated respectively with individuals’ pessimistic and optimistic attitudes toward life. Death-related words also increased the amplitude of a frontal/central positivity at 124–300 ms (P2) and of a frontal/central positivity at 300–500 ms (P3). However, the P2 and P3 modulations were observed for both death-related and negative-valence words but not for life-related words. The ERP results suggest an early inverse coding of linguistic cues related to life and death, which is followed by negative emotional responses to death-related information. PMID:23840787

  15. Control of impurity concentration in liquid metals by neutron scattering

    SciTech Connect

    Morozov, V. A.; Novikov, A. G.; Savostin, V. V.

    2011-12-15

    A technique is proposed for determining the impurity concentration in liquid metal-impurity systems. This technique does not require special measurements or geometry: information about the impurity concentration can be obtained directly from the data collected during the diffraction experiment. The impurity concentrations in a lead melt with a potassium impurity and in a sodium melt with a lead impurity are determined.

  16. 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.

  17. Screening for impurities in butoprozine.

    PubMed

    Drenth, B F; Jagersma, T; Wormeester, A J; de Zeeuw, R A

    1983-08-26

    The purity analysis of butoprozine is described. Both gas chromatography-mass spectrometry (GC-MS) and high pressure liquid chromatography (HPLC) with UV-vis detection (conventional and multichannel) were used. In the butoprozine example disadvantages for both techniques became apparent: incorrect conclusions with regard to the purity of the drug would have been drawn if only one of these chromatographic techniques had been used. GC-MS allowed the identification of an impurity not found by HPLC. PMID:6622208

  18. Impurities in Silicon Nanocrystals: The intentional and the inherent

    NASA Astrophysics Data System (ADS)

    Rowe, David J.

    Silicon nanocrystals (SiNCs) have become an important class of materials in the fields of photovoltaics, thermoelectrics, lighting, and medicine. Impurities within SiNCs dramatically alter the electrical and optical properties of the host material, whether the impurity is intentionally added in an attempt to manipulate properties, or is inherent to the material and its natural state. Despite such remarkable changes, impurity incorporation within SiNCs remains poorly understood, since concepts applied to understanding impurities in bulk materials may not completely translate to nanomaterials. Understanding the effect of SiNC impurities requires new technologies to produce materials suitable for study combined with new insights to expound the differences in the nanoscale physics. Nonthermal plasma-assisted gas-phase synthesis provides an excellent route to producing and investigating impurities within SiNCs due to the unique chemical reaction environment of the plasma. The robustness of such a technique allows for the production of very pure SiNCs or SiNCs with added impurities simply by adding different chemicals to the plasma. The chapters in this document focus on the effect that different impurities have on the properties of SiNCs. Chapter 2 focuses on heavily P-doped SiNCs exhibiting the first known observation of a unique electrical and optical property known as localized surface plasmon resonance (LSPR) within free-standing SiNCs. Chapter 3 explains the synthesis of B- and P-doped SiGeNC alloys and their deposition into thin films for thermoelectric applications. Chapter 4 highlights research which uses P-doped SiNCs to form emitter layers for pn-junction type solar cells, including device fabrication and optical characterization. Chapter 5 examines inherent impurities in the form of dangling bond defects which may be responsible for the quenching of SiNC photoluminescence, and their evolution during the process of air-ambient oxidation. Several appendices at

  19. The Reciprocal Relations between Morphological Processes and Reading

    ERIC Educational Resources Information Center

    Kruk, Richard S.; Bergman, Krista

    2013-01-01

    Reciprocal relations between emerging morphological processes and reading skills were examined in a longitudinal study tracking children from Grade 1 through Grade 3. The aim was to examine predictive relationships between productive morphological processing involving composing and decomposing of inflections and derivations, reading ability for…

  20. 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.

  1. 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.

  2. Invisible gold distribution on pyrite and ore-forming fluid process of the Huangshan orogenic-type gold deposit of Zhejiang, SE China: implications from mineralogy, trace elements, impurity and fluid inclusion studies

    NASA Astrophysics Data System (ADS)

    Sundarrajan, Vijay Anand; Li, Zilong; Hu, Yizhou; Fu, Xuheng; Zhu, Yuhuo

    2016-07-01

    The Huangshan orogenic-type gold deposit in Zhejiang of SE China occurred in quartz-pyrite veins. It is hosted by phyllonite that underwent greenschist-facies metamorphism along a large Jiangshan-Shaoxing tectonic belt with a NE-SW direction. Trace elemental characteristics, ore-forming process and invisible gold on different forms of pyrite and quartz are studied. The Au associated pyrite can be classified into two categories; recrystallized pyrite and euhedral pyrite. The precipitation of invisible Au on pyrite is mainly derived by Co and Ni with AuHS2 - complex in the mineralizing fluids in different events. The XPS results revealed that valence states of Au3+ replaced 2Fe2+ in the pyrite and Au0 replaced Si4+ in the quartz structure. The electron paramagnetic resonance and trace elemental results suggested that the element pairs of Ge-Li-Al in quartz and Mn-Co-Ni in pyrite have distinct impurities as identified. A fluid inclusion study showed that the auriferous quartz is characterized by low-saline and CO2-rich fluids. Coexistence of the type I-type III inclusions and same range of homogenization temperature with different mode are evidences of immiscible fluid process. The temperature-pressure values of ca. 250 °C/1250 bar and ca. 220 °C/780 bar for gold precipitation have been calculated by intersection of coexisting fluids during the entrapment. The Huangshan orogenic-type gold deposit may be associated with the Wuyi-Yunkai orogeny during the early Paleozoic, including an upper-mid greenschist-facies metamorphism (450-420 Ma). All the features suggest that the Huangshan gold deposit is probably a product linking with the early Paleozoic orogeny in South China.

  3. Methodology of Diagnostics of Interethnic Relations and Ethnosocial Processes

    ERIC Educational Resources Information Center

    Maximova, Svetlana G.; Noyanzina, Oksana Ye.; Omelchenko, Daria A.; Maximov, Maxim B.; Avdeeva, Galina C.

    2016-01-01

    The purpose of this study was to research the methodological approaches to the study of interethnic relations and ethno-social processes. The analysis of the literature was conducted in three main areas: 1) the theoretical and methodological issues of organizing the research of inter-ethnic relations, allowing to highlight the current…

  4. Event-Related Brain Potential Correlates of Emotional Face Processing

    ERIC Educational Resources Information Center

    Eimer, Martin; Holmes, Amanda

    2007-01-01

    Results from recent event-related brain potential (ERP) studies investigating brain processes involved in the detection and analysis of emotional facial expression are reviewed. In all experiments, emotional faces were found to trigger an increased ERP positivity relative to neutral faces. The onset of this emotional expression effect was…

  5. Computational Models of Relational Processes in Cognitive Development

    ERIC Educational Resources Information Center

    Halford, Graeme S.; Andrews, Glenda; Wilson, William H.; Phillips, Steven

    2012-01-01

    Acquisition of relational knowledge is a core process in cognitive development. Relational knowledge is dynamic and flexible, entails structure-consistent mappings between representations, has properties of compositionality and systematicity, and depends on binding in working memory. We review three types of computational models relevant to…

  6. Relational Processes in Career Transition: Extending Theory, Research, and Practice

    ERIC Educational Resources Information Center

    Motulsky, Sue L.

    2010-01-01

    A growing body of work in relational theory and career decision making explores how relational processes, not just people's relationships but more broadly their connections to self, others, and society, inform career development and counseling. This article presents the results of a qualitative research study of midlife women in career transition…

  7. On the entanglement of electronic states of impurity atoms in nanoparticles

    SciTech Connect

    Basharov, Askhat M; Znamenskiy, Nikolay V; Gorbachev, Valery N

    2006-08-31

    By using the derived master equations, it is shown that the decay of electronic impurities in a nanocrystal can be described as a collective relaxation of particles. A set of entangled states of impurity atoms is found, which have immunity to this relaxation. These states can be used for decoherence-free quantum processing. (quantum optics and information)

  8. Fairness influences early signatures of reward-related neural processing.

    PubMed

    Massi, Bart; Luhmann, Christian C

    2015-12-01

    Many humans exhibit a strong preference for fairness during decision-making. Although there is evidence that social factors influence reward-related and affective neural processing, it is unclear if this effect is mediated by compulsory outcome evaluation processes or results from slower deliberate cognition. Here we show that the feedback-related negativity (FRN) and late positive potential (LPP), two signatures of early hedonic processing, are modulated by the fairness of rewards during a passive rating task. We find that unfair payouts elicit larger FRNs than fair payouts, whereas fair payouts elicit larger LPPs than unfair payouts. This is true both in the time-domain, where the FRN and LPP are related, and in the time-frequency domain, where the two signals are largely independent. Ultimately, this work demonstrates that fairness affects the early stages of reward and affective processing, suggesting a common biological mechanism for social and personal reward evaluation.

  9. Methods for Dissecting Motivation and Related Psychological Processes in Rodents.

    PubMed

    Ward, Ryan D

    2016-01-01

    Motivational impairments are increasingly recognized as being critical to functional deficits and decreased quality of life in patients diagnosed with psychiatric disease. Accordingly, much preclinical research has focused on identifying psychological and neurobiological processes which underlie motivation . Inferring motivation from changes in overt behavioural responding in animal models, however, is complicated, and care must be taken to ensure that the observed change is accurately characterized as a change in motivation , and not due to some other, task-related process. This chapter discusses current methods for assessing motivation and related psychological processes in rodents. Using an example from work characterizing the motivational impairments in an animal model of the negative symptoms of schizophrenia, we highlight the importance of careful and rigorous experimental dissection of motivation and the related psychological processes when characterizing motivational deficits in rodent models . We suggest that such work is critical to the successful translation of preclinical findings to therapeutic benefits for patients.

  10. The reciprocal relations between morphological processes and reading.

    PubMed

    Kruk, Richard S; Bergman, Krista

    2013-01-01

    Reciprocal relations between emerging morphological processes and reading skills were examined in a longitudinal study tracking children from Grade 1 through Grade 3. The aim was to examine predictive relationships between productive morphological processing involving composing and decomposing of inflections and derivations, reading ability for pseudoword and word decoding, and word and passage reading comprehension after controlling for initial abilities in reading, morphological processing, phonological awareness, and vocabulary. Reciprocal influences were indicated by predictive relations among initial morphological processes and later reading abilities co-occurring with relationships between initial reading abilities and later morphological processes. Using multilevel modeling, decomposing and composing were found to predict emerging word decoding and word and passage comprehension but not pseudoword decoding. Reading comprehension predicted growth in decomposing. Subsequent regression analyses of model-estimated early linear growth in predictors and later linear growth in outcomes showed that early growth in morphological processes predicted later growth in word decoding and passage comprehension. Although reciprocal relations between emerging morphological processes and reading skills were observed, the different patterns on each side of the reciprocal "coin" indicated that the mechanisms underlying predictive influences are likely different but related to quality of lexical representations.

  11. Impurity studies in fusion devices using laser-fluorescence-spectroscopy

    SciTech Connect

    Husinsky, W.R.

    1980-08-01

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

  12. Deep impurity trapping concepts for power semiconductor devices

    NASA Technical Reports Server (NTRS)

    Sundberg, G. R.

    1982-01-01

    High voltage semiconductor switches using deep impurity doped silicon now appear feasible for high voltage (1-100 kV), high power (10 Kw) switching and protection functions for future space power applications. Recent discoveries have demonstrated several practical ways of gating deep impurity doped silicon devices in planar configurations and of electrically controlling their characteristics, leading to a vast array of possible circuit applications. A new family of semiconductor switching devices and transducers are possible based on this technology. New deep impurity devices could be simpler than conventional p-n junction devices and yet use the same basic materials and processing techniques. In addition, multiple functions may be possible on a single device as well as increased ratings.

  13. PROCESS FOR SEPARATING PLUTONIUM FROM IMPURITIES

    DOEpatents

    Wahl, A.C.

    1957-11-12

    A method is described for separating plutonium from aqueous solutions containing uranium. It has been found that if the plutonium is reduced to its 3+ valence state, and the uranium present is left in its higher valence state, then the differences in solubility between certain salts (e.g., oxalates) of the trivalent plutonium and the hexavalent uranium can be used to separate the metals. This selective reduction of plutonium is accomplished by adding iodide ion to the solution, since iodide possesses an oxidation potential sufficient to reduce plutonium but not sufficient to reduce uranium.

  14. Interstitial iron impurities at cores of dissociated dislocations in silicon

    NASA Astrophysics Data System (ADS)

    Ziebarth, Benedikt; Mrovec, Matous; Elsässer, Christian; Gumbsch, Peter

    2015-11-01

    Dislocations play an important role in semiconductor devices made of crystalline silicon (Si). They are known to be strongly performance-limiting defects in solar cell applications, since they act as preferred segregation sites for metallic impurities. In this work we investigate the segregation of iron (Fe) to the cores of the 30° and 90° partial dislocations in Si using atomistic calculations based on first-principles density functional theory. Our simulations show that interstitial Fe impurities segregate readily to all investigated cores and the driving force for the segregation increases with impurity concentration. Moreover, our analysis of the electronic structure reveals the existence of deep defect levels within the band gap that can be related to experimental observations by deep-level transient spectroscopy.

  15. 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.

  16. Spectroscopic studies of carbon impurities in PISCES-A

    SciTech Connect

    Ra, Y.; Hirooka, Y.; Leung, W.K.; Conn, R.W. . Inst. of Plasma and Fusion Research); Pospieszczyk, A. . Inst. fuer Plasmaphysik)

    1989-08-01

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

  17. Chemical modifications and stability of phosphorene with impurities: a first principles study.

    PubMed

    Boukhvalov, D W; Rudenko, A N; Prishchenko, D A; Mazurenko, V G; Katsnelson, M I

    2015-06-21

    We perform a systematic first-principles study of phosphorene in the presence of typical monovalent (hydrogen and fluorine) and divalent (oxygen) impurities. The results of our modeling suggest a decomposition of phosphorene into weakly bonded one-dimensional (1D) chains upon single- and double-side hydrogenation and fluorination. In spite of a sizable quasiparticle band gap (2.29 eV), fully hydrogenated phosphorene was found to be dynamically unstable. In contrast, complete fluorination of phosphorene gives rise to a stable structure, which is an indirect gap semiconductor with a band gap of 2.27 eV. We also show that fluorination of phosphorene from the gas phase is significantly more likely than hydrogenation due to the relatively low energy barrier for the dissociative adsorption of F2 (0.19 eV) compared to H2 (2.54 eV). At low concentrations, monovalent impurities tend to form regular atomic rows of phosphorene, though such patterns do not seem to be easily achievable due to high migration barriers (1.09 and 2.81 eV for H2 and F2, respectively). Oxidation of phosphorene is shown to be a qualitatively different process. Particularly, we observe instability of phosphorene upon oxidation, leading to the formation of disordered amorphous-like structures at high concentrations of impurities.

  18. 40 CFR 161.167 - Discussion of formation of impurities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... reactions and side reactions which may occur in the production of the product, and the relative amounts of byproduct impurities produced by such reactions. (iv) The possible degradation of the ingredients in the product after its production but prior to its use. (v) Post-production reactions between the...

  19. 40 CFR 161.167 - Discussion of formation of impurities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... reactions and side reactions which may occur in the production of the product, and the relative amounts of byproduct impurities produced by such reactions. (iv) The possible degradation of the ingredients in the product after its production but prior to its use. (v) Post-production reactions between the...

  20. 40 CFR 161.167 - Discussion of formation of impurities.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... reactions and side reactions which may occur in the production of the product, and the relative amounts of byproduct impurities produced by such reactions. (iv) The possible degradation of the ingredients in the product after its production but prior to its use. (v) Post-production reactions between the...

  1. 40 CFR 161.167 - Discussion of formation of impurities.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... reactions and side reactions which may occur in the production of the product, and the relative amounts of byproduct impurities produced by such reactions. (iv) The possible degradation of the ingredients in the product after its production but prior to its use. (v) Post-production reactions between the...

  2. Modeling of multi-dimensional impurity transport in a realistic tokamak geometry

    NASA Astrophysics Data System (ADS)

    Fukano, A.; Noritake, M.; Hoshino, K.; Yamazaki, R.; Hatayama, A.

    2007-06-01

    A 3D Monte Carlo transport code of heavy metal impurities is developed. The code includes most of important processes of heavy metal impurities, such as Larmor gyration, friction force, Coulomb collision, multi-step ionization and recombination process. The code outputs the 2D density profiles of tungsten impurity on realistic tokamak geometry. Calculations are made for given background plasma profiles for attached and detached plasma, which are the typical conditions in front of the divertor plate. In the attached plasma state, impurity tungsten particles are ionized to higher charge states near the divertor plate due to high background plasma electron temperature. On the other hand, in the detached plasma state, ions in higher charge states exist in the upstream of the divertor region mainly due to low background plasma electron temperature in front of the target plate. Although the code is still under development, it well describes the qualitative feature of impurity transport in the realistic tokamak geometry.

  3. Engineering aspects of rate-related processes in food manufacturing.

    PubMed

    Adachi, Shuji

    2015-01-01

    Many rate-related phenomena occur in food manufacturing processes. This review addresses four of them, all of which are topics that the author has studied in order to design food manufacturing processes that are favorable from the standpoint of food engineering. They include chromatographic separation through continuous separation with a simulated moving adsorber, lipid oxidation kinetics in emulsions and microencapsulated systems, kinetic analysis and extraction in subcritical water, and water migration in pasta.

  4. Selecting public relations personnel of hospitals by analytic network process.

    PubMed

    Liao, Sen-Kuei; Chang, Kuei-Lun

    2009-01-01

    This study describes the use of analytic network process (ANP) in the Taiwanese hospital public relations personnel selection process. Starting with interviewing 48 practitioners and executives in north Taiwan, we collected selection criteria. Then, we retained the 12 critical criteria that were mentioned above 40 times by theses respondents, including: interpersonal skill, experience, negotiation, language, ability to follow orders, cognitive ability, adaptation to environment, adaptation to company, emotion, loyalty, attitude, and Response. Finally, we discussed with the 20 executives to take these important criteria into three perspectives to structure the hierarchy for hospital public relations personnel selection. After discussing with practitioners and executives, we find that selecting criteria are interrelated. The ANP, which incorporates interdependence relationships, is a new approach for multi-criteria decision-making. Thus, we apply ANP to select the most optimal public relations personnel of hospitals. An empirical study of public relations personnel selection problems in Taiwan hospitals is conducted to illustrate how the selection procedure works.

  5. Processing relative clauses by Hungarian typically developing children

    PubMed Central

    Kas, Bence; Lukács, Ágnes

    2011-01-01

    Hungarian is a language with morphological case marking and relatively free word order. These typological characteristics make it a good ground for testing the crosslinguistic validity of theories on processing sentences with relative clauses. Our study focussed on effects of structural factors and processing capacity. We tested 43 typically developing children in two age groups (ages of 4;11–7;2 and 8;2–11;4) in an act-out task. Differences in comprehension difficulty between different word order patterns and different head function relations were observed independently of each other. The structural properties causing difficulties in comprehension were interruption of main clauses, greater distance between the verb and its arguments, accusative case of relative pronouns, and SO head function relations. Importantly, analyses of associations between working memory and sentence comprehension revealed that structural factors made processing difficult by burdening components of working memory. These results support processing accounts of sentence comprehension in a language typologically different from English. PMID:22888179

  6. Anisotropic inflation from vector impurity

    SciTech Connect

    Kanno, Sugumi; Kimura, Masashi; Soda, Jiro; Yokoyama, Shuichiro E-mail: mkimura@sci.osaka-cu.ac.jp E-mail: shu@a.phys.nagoya-u.ac.jp

    2008-08-15

    We study an inflationary scenario with a vector impurity. We show that the universe undergoes anisotropic inflationary expansion due to a preferred direction determined by the vector. Using the slow roll approximation, we find a formula for determining the anisotropy of the inflationary universe. We discuss possible observable predictions of this scenario. In particular, it is stressed that primordial gravitational waves can be induced from curvature perturbations. Hence, even in low scale inflation, a sizable amount of primordial gravitational waves may be produced during inflation.

  7. 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}

  8. Event-Related Potentials and Emotion Processing in Child Psychopathology

    PubMed Central

    Chronaki, Georgia

    2016-01-01

    In recent years there has been increasing interest in the neural mechanisms underlying altered emotional processes in children and adolescents with psychopathology. This review provides a brief overview of the most up-to-date findings in the field of event-related potentials (ERPs) to facial and vocal emotional expressions in the most common child psychopathological conditions. In regards to externalizing behavior (i.e., ADHD, CD), ERP studies show enhanced early components to anger, reflecting enhanced sensory processing, followed by reductions in later components to anger, reflecting reduced cognitive-evaluative processing. In regards to internalizing behavior, research supports models of increased processing of threat stimuli especially at later more elaborate and effortful stages. Finally, in autism spectrum disorders abnormalities have been observed at early visual-perceptual stages of processing. An affective neuroscience framework for understanding child psychopathology can be valuable in elucidating underlying mechanisms and inform preventive intervention. PMID:27199803

  9. Event-Related Potentials and Emotion Processing in Child Psychopathology.

    PubMed

    Chronaki, Georgia

    2016-01-01

    In recent years there has been increasing interest in the neural mechanisms underlying altered emotional processes in children and adolescents with psychopathology. This review provides a brief overview of the most up-to-date findings in the field of event-related potentials (ERPs) to facial and vocal emotional expressions in the most common child psychopathological conditions. In regards to externalizing behavior (i.e., ADHD, CD), ERP studies show enhanced early components to anger, reflecting enhanced sensory processing, followed by reductions in later components to anger, reflecting reduced cognitive-evaluative processing. In regards to internalizing behavior, research supports models of increased processing of threat stimuli especially at later more elaborate and effortful stages. Finally, in autism spectrum disorders abnormalities have been observed at early visual-perceptual stages of processing. An affective neuroscience framework for understanding child psychopathology can be valuable in elucidating underlying mechanisms and inform preventive intervention. PMID:27199803

  10. Impurities in pretreated biowaste for co-digestion: A determination approach.

    PubMed

    Jank, Anna; Müller, Wolfgang; Waldhuber, Sebastian; Gerke, Frédéric; Ebner, Christian; Bockreis, Anke

    2016-06-01

    Although the mechanical treatment of source separated organic waste typically includes processing steps to remove impurities like plastic bags, smaller particles like glass, stones or sand are often not sufficiently removed. These particles lead to plant malfunctions, increased equipment abrasion and accumulation in the digester. It is possible to remove these small impurities before or during the fermentation process but this requires additional equipment at the waste treatment facilities. For pretreated biowaste with fairly low concentrations of impurities and small particle sizes no appropriate method was found in literature to determine these particles. Therefore various approaches to develop an appropriate method were tested and finally one method was selected. Sample mass calculation showed that for the determination of impurities >2mm a sample mass of about 6kg is required to receive statistically sound result. Firstly an elutriation step is used to concentrate the impurities in a sinking fraction, still containing some organic material. The elutriated material is then dried. After drying the elutriated material, impurities can be fairly easily sorted manually. The elutriation process is applicable for the determination of impurities >1mm. Due to the difficult manual sorting of particles <2mm and the reduced sample mass required for the determination of particles <2mm, these particles are determined by a different procedure: A sample mass of about 1kg is dried and combusted in a muffle furnace. The remaining ashes are sieved from 2 to 0.06mm. Particles <0.06mm were not considered as impurities. The data regarding the impurities content and particle size distribution in food- and biowaste are required for assessing separation options as well as the behavior of stones or sand in the digester. This allows describing the quality of the pretreated biowaste. Furthermore the need to adopt or improve the existing pretreatment can be identified and the impact to the

  11. Relation between Phonological Processing, Auditory Processing and Speech Perception among Bilingual Poor Readers

    PubMed Central

    2015-01-01

    Background and Objectives A deficit in phonological processing abilities has been hypothesized as a cause of reading deficits among poor readers, but the precise etiology of this deficit is still unknown. Many studies have investigated the relation of auditory processing and speech perception with phonological processing, while the relation between these are not well understood. Thus, the present study was carried out to investigate the relation between these abilities among poor readers. Subjects and Methods A total of 20 children between 7-12 years of age participated in the study. Among these 10 were typically developing children and 10 were poor readers. Auditory processing, speech perception in noise and phonological processing skills were assessed in both the groups. Results Auditory processing was not significantly different between children in both the groups. In contrast, phonological awareness, verbal short-term memory and rapid automatized naming, which reflect phonological processing, and speech perception in noise were found to be significantly affected in poor readers. In addition, the results showed a significant correlation between phonological processing and speech perception in noise. Conclusions The present study found a significant relationship between speech perception in noise and phonological processing, while there was no relationship between auditory processing and phonological processing. This finding suggests that poor speech perception among poor readers may be one of the contributing factors for phonological processing deficits, which in turn leads to reading difficulties. PMID:26771010

  12. Analysis of delamination related fracture processes in composites

    NASA Technical Reports Server (NTRS)

    Armanios, Erian A.

    1988-01-01

    Delamination related fracture processes in composite materials are discussed. Thermal and moisture influences on the free-edge delamination of laminated composites, fracture analysis of local delaminations in laminated composites, and strain energy release rates in belts are among the topics covered.

  13. Graphic Arts: Book Three. The Press and Related Processes.

    ERIC Educational Resources Information Center

    Farajollahi, Karim; And Others

    The third of a three-volume set of instructional materials for a graphic arts course, this manual consists of nine instructional units dealing with presses and related processes. Covered in the units are basic press fundamentals, offset press systems, offset press operating procedures, offset inks and dampening chemistry, preventive maintenance…

  14. Relational Themes in Counseling Supervision: Broadening and Narrowing Processes

    ERIC Educational Resources Information Center

    Gazzola, Nicola; Theriault, Anne

    2007-01-01

    This study investigated the experiences of broadening (i.e., thinking and acting creatively and being open to exploring new ways of being) and narrowing (i.e., the experience of perceiving one's choices as limited) in the supervisory process with the aim of identifying key relational themes from the perspective of supervisees. We interviewed 10…

  15. Feed Basis for Processing Relatively Low Radioactivity Waste Tanks

    SciTech Connect

    Jones , R.T.

    2003-02-18

    This paper presents the characterization of potential feed for processing relatively low radioactive waste tanks. The feed characterization is based on waste characterization data extracted from the waste characterization system. This data is compared to salt cake sample results from Tanks 37, 38, and 41.

  16. Feed Basis for Processing Relatively Low Radioactivity Waste Tanks

    SciTech Connect

    Pike, J.A.

    2002-07-09

    This paper presents the characterization of potential feed for processing relatively low radioactive waste tanks. The feed characterization is based on waste characterization data extracted from the waste characterization system. This data is compared to salt cake sample results from Tanks 37, 38 and 41.

  17. Processing Relative Clauses in Chinese as a Second Language

    ERIC Educational Resources Information Center

    Xu, Yi

    2014-01-01

    This project investigates second language (L2) learners' processing of four types of Chinese relative clauses crossing extraction types and demonstrative-classifier (DCl) positions. Using a word order judgment task with a whole-sentence reading technique, the study also discusses how psycholinguistic theories bear explanatory power in L2…

  18. Information-Processing Modules and Their Relative Modality Specificity

    ERIC Educational Resources Information Center

    Anderson, John R.; Qin, Yulin; Jung, Kwan-Jin; Carter, Cameron S.

    2007-01-01

    This research uses fMRI to understand the role of eight cortical regions in a relatively complex information-processing task. Modality of input (visual versus auditory) and modality of output (manual versus vocal) are manipulated. Two perceptual regions (auditory cortex and fusiform gyrus) only reflected perceptual encoding. Two motor regions were…

  19. Item and relational processing in young and older adults.

    PubMed

    Fisher, L M; McDowd, J M

    1993-03-01

    The item and relational information framework of memory provided a methodology for an analytical approach to age differences in encoding and retrieval processes. Subjects were given related or unrelated words to sort or rate for pleasantness. Young adults performed better than older adults in free recall, but older adults were able to use both item and relational information as well as young adults. In a second experiment, subjects also sorted or rated a list composed of different numbers of category items. The pattern of free recall and cued recall scores indicated that item and relational information affected the memory performance of both age groups in a similar fashion. By examining memory in terms of item and relational information, it appears that older adults do not have difficulty combining two types of target information during encoding and that the information assists in recall of target items. PMID:8473699

  20. 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.

  1. 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.

  2. Fostering new relational experience: clinical process in couple psychotherapy.

    PubMed

    Marmarosh, Cheri L

    2014-03-01

    One of the most critical goals for couple psychotherapy is to foster a new relational experience in the session where the couple feels safe enough to reveal more vulnerable emotions and to explore their defensive withdrawal, aggressive attacking, or blaming. The lived intimate experience in the session offers the couple an opportunity to gain integrative insight into their feelings, expectations, and behaviors that ultimately hinder intimacy. The clinical processes that are necessary include empathizing with the couple and facilitating safety within the session, looking for opportunities to explore emotions, ruptures, and unconscious motivations that maintain distance in the relationship, and creating a new relational experience in the session that has the potential to engender integrative insight. These clinical processes will be presented with empirical support. Experts from a session will be used to highlight how these processes influence the couple and promote increased intimacy. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24059733

  3. Syntactic processing with aging: an event-related potential study.

    PubMed

    Kemmer, Laura; Coulson, Seana; De Ochoa, Esmeralda; Kutas, Marta

    2004-05-01

    To assess age-related changes in simple syntactic processing with normal aging, event-related brain potentials (ERPs) elicited by grammatical number violations as individuals read sentences for comprehension were analyzed. Violations were found to elicit a P600 of equal amplitude and latency regardless of an individual's age. Instead, advancing age was associated with a change in the scalp distribution of the P600 effect, being less asymmetric and more frontal (though still with a parietal maximum) in older than younger adults. Our results thus show that the brain's response to simple syntactic violations, unlike those reported for simple binary categorizations and simple semantic violations, is neither slowed nor diminished in amplitude by age. At the same time, the brain's processing of these grammatical number violations did engage at least somewhat different brain regions as a function of age, suggesting a qualitative change rather than any simple quantitative change in speed of processing.

  4. Processing Chinese Relative Clauses: Evidence for the Subject-Relative Advantage

    PubMed Central

    Vasishth, Shravan; Chen, Zhong; Li, Qiang; Guo, Gueilan

    2013-01-01

    A general fact about language is that subject relative clauses are easier to process than object relative clauses. Recently, several self-paced reading studies have presented surprising evidence that object relatives in Chinese are easier to process than subject relatives. We carried out three self-paced reading experiments that attempted to replicate these results. Two of our three studies found a subject-relative preference, and the third study found an object-relative advantage. Using a random effects bayesian meta-analysis of fifteen studies (including our own), we show that the overall current evidence for the subject-relative advantage is quite strong (approximate posterior probability of a subject-relative advantage given the data: 78–80%). We argue that retrieval/integration based accounts would have difficulty explaining all three experimental results. These findings are important because they narrow the theoretical space by limiting the role of an important class of explanation—retrieval/integration cost—at least for relative clause processing in Chinese. PMID:24098575

  5. Process-induced defects in terrestrial solar cells

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.; Li, S. S.; Sah, C. T.

    1975-01-01

    Experimental and theoretical work on low resistivity, high efficiency solar cells indicates the dominant role that defects take in determining performance. High doping mechanisms produce gap shrinkage by band tailing, impurity band widening and impurity misfit; altered interband transmission rates result from Auger impact, SRH processes, or from electronic tunneling via defects. Characterizations of cell materials for their defects and their relations to the chosen fabrication processes are proposed.

  6. Reduced-Order Kalman Filtering for Processing Relative Measurements

    NASA Technical Reports Server (NTRS)

    Bayard, David S.

    2008-01-01

    A study in Kalman-filter theory has led to a method of processing relative measurements to estimate the current state of a physical system, using less computation than has previously been thought necessary. As used here, relative measurements signifies measurements that yield information on the relationship between a later and an earlier state of the system. An important example of relative measurements arises in computer vision: Information on relative motion is extracted by comparing images taken at two different times. Relative measurements do not directly fit into standard Kalman filter theory, in which measurements are restricted to those indicative of only the current state of the system. One approach heretofore followed in utilizing relative measurements in Kalman filtering, denoted state augmentation, involves augmenting the state of the system at the earlier of two time instants and then propagating the state to the later time instant.While state augmentation is conceptually simple, it can also be computationally prohibitive because it doubles the number of states in the Kalman filter. When processing a relative measurement, if one were to follow the state-augmentation approach as practiced heretofore, one would find it necessary to propagate the full augmented state Kalman filter from the earlier time to the later time and then select out the reduced-order components. The main result of the study reported here is proof of a property called reduced-order equivalence (ROE). The main consequence of ROE is that it is not necessary to augment with the full state, but, rather, only the portion of the state that is explicitly used in the partial relative measurement. In other words, it suffices to select the reduced-order components first and then propagate the partial augmented state Kalman filter from the earlier time to the later time; the amount of computation needed to do this can be substantially less than that needed for propagating the full augmented

  7. Experimental studies of ionospheric irregularities and related plasma processes

    NASA Technical Reports Server (NTRS)

    Baker, Kay D.

    1992-01-01

    Utah State University (USU) continued its program of measuring and interpreting electron density and its variations in a variety of ionospheric conditions with the Experimental Studies of Ionospheric Irregularities and Related Plasma Processes program. The program represented a nearly ten year effort to provide key measurements of electron density and its fluctuations using sounding rockets. The program also involved the joint interpretation of the results in terms of ionospheric processes. A complete campaign summary and a brief description of the major rocket campaigns are also included.

  8. An inverse relation between event-related and time-frequency violation responses in sentence processing.

    PubMed

    Davidson, D J; Indefrey, P

    2007-07-16

    The relationship between semantic and grammatical processing in sentence comprehension was investigated by examining event-related potential (ERP) and event-related power changes in response to semantic and grammatical violations. Sentences with semantic, phrase structure, or number violations and matched controls were presented serially (1.25 words/s) to 20 participants while EEG was recorded. Semantic violations were associated with an N400 effect and a theta band increase in power, while grammatical violations were associated with a P600 effect and an alpha/beta band decrease in power. A quartile analysis showed that for both types of violations, larger average violation effects were associated with lower relative amplitudes of oscillatory activity, implying an inverse relation between ERP amplitude and event-related power magnitude change in sentence processing.

  9. Quasiparticle states and quantum interference induced by magnetic impurities on a two-dimensional topological superconductor.

    PubMed

    Fu, Zhen-Guo; Zhang, Ping; Wang, Zhigang; Li, Shu-Shen

    2012-04-11

    We theoretically study the effect of localized magnetic impurities on two-dimensional topological superconductor (TSC). We show that the local density of states (LDOS) can be tuned by the effective exchange field m, the chemical potential μ of TSC, and the distance Δr as well as the relative spin angle α between two impurities. The changes in Δr between two impurities alter the interference and result in significant modifications to the bonding and antibonding states. Furthermore, the bound-state spin LDOS induced by single and double magnetic impurity scattering, the quantum corrals and the quantum mirages are also discussed. Finally, we briefly compare the impurities in TSC with those in topological insulators.

  10. Statistics-related and reliability-physics-related failure processes in electronics devices and products

    NASA Astrophysics Data System (ADS)

    Suhir, E.

    2014-05-01

    The well known and widely used experimental reliability "passport" of a mass manufactured electronic or a photonic product — the bathtub curve — reflects the combined contribution of the statistics-related and reliability-physics (physics-of-failure)-related processes. When time progresses, the first process results in a decreasing failure rate, while the second process associated with the material aging and degradation leads to an increased failure rate. An attempt has been made in this analysis to assess the level of the reliability physics-related aging process from the available bathtub curve (diagram). It is assumed that the products of interest underwent the burn-in testing and therefore the obtained bathtub curve does not contain the infant mortality portion. It has been also assumed that the two random processes in question are statistically independent, and that the failure rate of the physical process can be obtained by deducting the theoretically assessed statistical failure rate from the bathtub curve ordinates. In the carried out numerical example, the Raleigh distribution for the statistical failure rate was used, for the sake of a relatively simple illustration. The developed methodology can be used in reliability physics evaluations, when there is a need to better understand the roles of the statistics-related and reliability-physics-related irreversible random processes in reliability evaluations. The future work should include investigations on how powerful and flexible methods and approaches of the statistical mechanics can be effectively employed, in addition to reliability physics techniques, to model the operational reliability of electronic and photonic products.

  11. 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.

  12. Emotional and movement-related body postures modulate visual processing.

    PubMed

    Borhani, Khatereh; Làdavas, Elisabetta; Maier, Martin E; Avenanti, Alessio; Bertini, Caterina

    2015-08-01

    Human body postures convey useful information for understanding others' emotions and intentions. To investigate at which stage of visual processing emotional and movement-related information conveyed by bodies is discriminated, we examined event-related potentials elicited by laterally presented images of bodies with static postures and implied-motion body images with neutral, fearful or happy expressions. At the early stage of visual structural encoding (N190), we found a difference in the sensitivity of the two hemispheres to observed body postures. Specifically, the right hemisphere showed a N190 modulation both for the motion content (i.e. all the observed postures implying body movements elicited greater N190 amplitudes compared with static postures) and for the emotional content (i.e. fearful postures elicited the largest N190 amplitude), while the left hemisphere showed a modulation only for the motion content. In contrast, at a later stage of perceptual representation, reflecting selective attention to salient stimuli, an increased early posterior negativity was observed for fearful stimuli in both hemispheres, suggesting an enhanced processing of motivationally relevant stimuli. The observed modulations, both at the early stage of structural encoding and at the later processing stage, suggest the existence of a specialized perceptual mechanism tuned to emotion- and action-related information conveyed by human body postures. PMID:25556213

  13. Emotional and movement-related body postures modulate visual processing.

    PubMed

    Borhani, Khatereh; Làdavas, Elisabetta; Maier, Martin E; Avenanti, Alessio; Bertini, Caterina

    2015-08-01

    Human body postures convey useful information for understanding others' emotions and intentions. To investigate at which stage of visual processing emotional and movement-related information conveyed by bodies is discriminated, we examined event-related potentials elicited by laterally presented images of bodies with static postures and implied-motion body images with neutral, fearful or happy expressions. At the early stage of visual structural encoding (N190), we found a difference in the sensitivity of the two hemispheres to observed body postures. Specifically, the right hemisphere showed a N190 modulation both for the motion content (i.e. all the observed postures implying body movements elicited greater N190 amplitudes compared with static postures) and for the emotional content (i.e. fearful postures elicited the largest N190 amplitude), while the left hemisphere showed a modulation only for the motion content. In contrast, at a later stage of perceptual representation, reflecting selective attention to salient stimuli, an increased early posterior negativity was observed for fearful stimuli in both hemispheres, suggesting an enhanced processing of motivationally relevant stimuli. The observed modulations, both at the early stage of structural encoding and at the later processing stage, suggest the existence of a specialized perceptual mechanism tuned to emotion- and action-related information conveyed by human body postures.

  14. Snore related signals processing in a private cloud computing system.

    PubMed

    Qian, Kun; Guo, Jian; Xu, Huijie; Zhu, Zhaomeng; Zhang, Gongxuan

    2014-09-01

    Snore related signals (SRS) have been demonstrated to carry important information about the obstruction site and degree in the upper airway of Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) patients in recent years. To make this acoustic signal analysis method more accurate and robust, big SRS data processing is inevitable. As an emerging concept and technology, cloud computing has motivated numerous researchers and engineers to exploit applications both in academic and industry field, which could have an ability to implement a huge blue print in biomedical engineering. Considering the security and transferring requirement of biomedical data, we designed a system based on private cloud computing to process SRS. Then we set the comparable experiments of processing a 5-hour audio recording of an OSAHS patient by a personal computer, a server and a private cloud computing system to demonstrate the efficiency of the infrastructure we proposed. PMID:25205499

  15. Research of personal decision process using event-related potentials

    NASA Astrophysics Data System (ADS)

    Li, Xiaofeng

    2011-10-01

    To gain insights into the neural basis of such adaptive decision-making processes, we investigated the nature of learning process in humans playing a competitive game with binary choices, using a matching pennies game. As in reinforcement learning, the subject's choice during a competitive game was biased by its choice and reward history, as well as by the strategies of its opponent. Analyses of ERP data focused on the feedback-related negativity (FRN), we found that the magnitude of ERPs after losing to the computer opponent predicted whether subjects would change decision behavior on the subsequent trial. These findings provide novel evidence that humans engage a reinforcement learning process to adjust representations of competing decision options.

  16. Snore related signals processing in a private cloud computing system.

    PubMed

    Qian, Kun; Guo, Jian; Xu, Huijie; Zhu, Zhaomeng; Zhang, Gongxuan

    2014-09-01

    Snore related signals (SRS) have been demonstrated to carry important information about the obstruction site and degree in the upper airway of Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) patients in recent years. To make this acoustic signal analysis method more accurate and robust, big SRS data processing is inevitable. As an emerging concept and technology, cloud computing has motivated numerous researchers and engineers to exploit applications both in academic and industry field, which could have an ability to implement a huge blue print in biomedical engineering. Considering the security and transferring requirement of biomedical data, we designed a system based on private cloud computing to process SRS. Then we set the comparable experiments of processing a 5-hour audio recording of an OSAHS patient by a personal computer, a server and a private cloud computing system to demonstrate the efficiency of the infrastructure we proposed.

  17. Impurity accumulation in plasma regimes with high energy confinement

    NASA Astrophysics Data System (ADS)

    Ran, L. B.; Roberts, D. E.; Yang, H. R.; Dodel, G.; Gentle, K.; Von Goeler, S.; Holzhauer, E.; Hübner, K.; Keilhacker, M.; Korotkov, A.; Luce, T. C.; Miura, Y.; Tsois, N.; Würz, H.; Fussmann, G.; Hofmann, J.; Janeschitz, G.; Krieger, K.; Müller, E. R.; Nolte, R.; Röhr, H.; Steuer, K. H.; Becker, G.; Bomba, B.; Bruhns, H.; Büchl, K.; Carlson, A.; Eberhagen, A.; Fahrbach, H.-U.; Gehre, O.; Gernhardt, J.; Giannone, L.; Von Gierke, G.; Glock, E.; Gruber, O.; Haas, G.; Herrmann, H.; Kaesdorf, S.; Karger, F.; Kaufmann, M.; Klüber, O.; Kornherr, M.; Lackner, K.; Lang, R.; Lee, P.; Lisitano, G.; Mast, F.; Mayer, H. M.; McCormick, K.; Meisel, D.; Mertens, V.; Murmann, H.; Neuhauser, J.; Niedermeyer, H.; Noterdaeme, J. M.; Poschenrieder, W.; Preis, R.; Rapp, H.; Rudyj, A.; Sandmann, W.; Schneider, F.; Schnider, U.; Siller, G.; Simmet, E.; Speth, E.; Söldner, F.; Stäbler, A.; Steinmetz, K.; Stroth, U.; Vollmer, O.; Zasche, D.

    1989-04-01

    Investigations of impurity accumulation phenomena in ASDEX are reviewed. There are four different operating regimes where pronounced accumulation is observed and these regimes are also characterized by improved energy confinement. In particular, medium-Z metallic ions are involved in accumulation processes whereas low-Z ions appear almost unaffected. The rapid accumulation observed in the case of metallic ions may be explained by neoclassical inward drifts if we assume that the anomalous diffusion is sufficiently suppressed, some indication of this being found from laser blow-off studies. The present results, however, can only be partly explained by neoclassical theory, according to which accumulation of low-Z impurities should also occur. The temporal behaviour of accumulation and the retarding effect of proton dilution for collision dominated transport are also discussed. Finally, we conclude that the full benefits of improved energy confinement can be achieved only if the impurity influxes are kept to a sufficiently low level. Expressed in terms of concentrations under low confinement conditions we have to postulate, for ASDEX, concentrations ≲ 10 -4 for metals and ≲ 2% for all light impurities.

  18. Selecting public relations personnel of hospitals by analytic network process.

    PubMed

    Liao, Sen-Kuei; Chang, Kuei-Lun

    2009-01-01

    This study describes the use of analytic network process (ANP) in the Taiwanese hospital public relations personnel selection process. Starting with interviewing 48 practitioners and executives in north Taiwan, we collected selection criteria. Then, we retained the 12 critical criteria that were mentioned above 40 times by theses respondents, including: interpersonal skill, experience, negotiation, language, ability to follow orders, cognitive ability, adaptation to environment, adaptation to company, emotion, loyalty, attitude, and Response. Finally, we discussed with the 20 executives to take these important criteria into three perspectives to structure the hierarchy for hospital public relations personnel selection. After discussing with practitioners and executives, we find that selecting criteria are interrelated. The ANP, which incorporates interdependence relationships, is a new approach for multi-criteria decision-making. Thus, we apply ANP to select the most optimal public relations personnel of hospitals. An empirical study of public relations personnel selection problems in Taiwan hospitals is conducted to illustrate how the selection procedure works. PMID:19197656

  19. Substitutional 4d and 5d impurities in graphene.

    PubMed

    Alonso-Lanza, Tomás; Ayuela, Andrés; Aguilera-Granja, Faustino

    2016-08-21

    We describe the structural and electronic properties of graphene doped with substitutional impurities of 4d and 5d transition metals. The adsorption energies and distances for 4d and 5d metals in graphene show similar trends for the later groups in the periodic table, which are also well-known characteristics of 3d elements. However, along earlier groups the 4d impurities in graphene show very similar adsorption energies, distances and magnetic moments to the 5d ones, which can be related to the influence of the 4d and 5d lanthanide contraction. Surprisingly, within the manganese group, the total magnetic moment of 3 μB for manganese is reduced to 1 μB for technetium and rhenium. We find that compared with 3d elements, the larger size of the 4d and 5d elements causes a high degree of hybridization with the neighbouring carbon atoms, reducing spin splitting in the d levels. It seems that the magnetic adjustment of graphene could be significantly different if 4d or 5d impurities are used instead of 3d impurities.

  20. Substitutional 4d and 5d impurities in graphene.

    PubMed

    Alonso-Lanza, Tomás; Ayuela, Andrés; Aguilera-Granja, Faustino

    2016-08-21

    We describe the structural and electronic properties of graphene doped with substitutional impurities of 4d and 5d transition metals. The adsorption energies and distances for 4d and 5d metals in graphene show similar trends for the later groups in the periodic table, which are also well-known characteristics of 3d elements. However, along earlier groups the 4d impurities in graphene show very similar adsorption energies, distances and magnetic moments to the 5d ones, which can be related to the influence of the 4d and 5d lanthanide contraction. Surprisingly, within the manganese group, the total magnetic moment of 3 μB for manganese is reduced to 1 μB for technetium and rhenium. We find that compared with 3d elements, the larger size of the 4d and 5d elements causes a high degree of hybridization with the neighbouring carbon atoms, reducing spin splitting in the d levels. It seems that the magnetic adjustment of graphene could be significantly different if 4d or 5d impurities are used instead of 3d impurities. PMID:27439363

  1. Immunological processes related to cognitive impairment in MS.

    PubMed

    Berger, T

    2016-09-01

    In this review, the immune-to-brain communication pathways are briefly summarized, with emphasis on the impact of immune cells and their mediators on learning, memory and other cognitive domains. Further, the acute response of the central nervous system to peripherally generated inflammatory stimuli - termed as sickness behaviour - is described, and the central role of microglia in this immune-to-brain crosstalk in physiological and pathological conditions is highlighted. Finally, the role and consequences of immunological processes related to cognitive impairment in multiple sclerosis are discussed. PMID:27580904

  2. Complementary relations in non-equilibrium stochastic processes

    NASA Astrophysics Data System (ADS)

    Kim, Eun-jin; Nicholson, S. B.

    2015-08-01

    We present novel complementary relations in non-equilibrium stochastic processes. Specifically, by utilising path integral formulation, we derive statistical measures (entropy, information, and work) and investigate their dependence on variables (x, v), reference frames, and time. In particular, we show that the equilibrium state maximises the simultaneous information quantified by the product of the Fisher information based on x and v while minimising the simultaneous disorder/uncertainty quantified by the sum of the entropy based on x and v as well as by the product of the variances of the PDFs of x and v. We also elucidate the difference between Eulerian and Lagrangian entropy. Our theory naturally leads to Hamilton-Jacobi relation for forced-dissipative systems.

  3. 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.

  4. Theory of Valence-Fluctuating Tm Impurities. I

    NASA Astrophysics Data System (ADS)

    Saso, Tetsuro

    1989-11-01

    A new formalism is presented for describing mixed valent Tm impurities fluctuating between two magnetic configurations. Based on the self-consistent perturbation scheme, the present formalism incorporates not only the valence fluctuation between 4f12 and 4f13, but also the multiscattering process of 4f13 and a conduction electron, yielding a singlet bound state. Thus the ground state is a Kondo singlet, which however is different from the ordinary Kondo state and conceptually new in that the length of the local moment of the impurity is fluctuating between the two values j{=}6 and J{=}7/2. Numerical calculations are presented for the spectral distribution function of these states. Systematic study of the Kondo temperature TK yields that TK is substantially low when the number of f electrons is close to 12. Contribution of the above scattering processes to the f-electron spectral function and the magnetic susceptibility is also disscussed.

  5. Operation of the Oxide Washer for Water-Washing Solubles out of Impure Pu Oxide

    SciTech Connect

    Dodson, K E; Close, W L; Krikorian, O H; Summers III, H V

    2006-01-30

    An evaluation has been made for using the Oxide Washer to wash water-soluble materials out of impure Pu oxide. It is found that multiple washes are needed to reduce the water-soluble materials to very low levels in the impure Pu oxides. The removal of the wash water from the Oxide Washer is accompanied by particulates of the impure Pu oxide, which subsequently need to be filtered out. In spite of the additional filtration needed, the overall level of manpower required for processing is still only about one third of that for an all-manual operation.

  6. The impact of CO2 impurities (SO2, NOx, O2) on mineral dissolution/precipitation processes in a CO2 storage reservoir - Field-based results from the CO2CRC Otway Project site

    NASA Astrophysics Data System (ADS)

    Vu, H. P.; Black, J. R.; Haese, R. R.

    2015-12-01

    CO2 storage with impurities such as O2, NOx and SO2 is increasingly considered, because the complete removal of impurities is costly. Theoretical and laboratory-based studies have mostly focused on the formation of sulfuric and nitric acid from SO2 and NOx, respectively, while redox reactions induced by the co-injection of O2 have received little attention. Here we present results from the first field-based experiment pointing to an important role of O2. At the CO2CRC Otway Project site, CO2 and CO2 enriched with impurities (54 ppm SO2, 9 ppm NOx and 6150 ppm O2) were mixed at depth with water leading to CO2 saturated water. The CO2 saturated water was then allowed to react with the reservoir at a depth of 1400 m (Paaratte Formation, Otway Basin) over a total of 23 days. Reservoir water at in situ pressure conditions was taken for analyses using the U-tube sampling system. Back-produced water showed no evidence of silica or carbonate mineral dissolution, which can be explained by the level of alkalinity effectively buffering the additional acidity (as the result of the co-injection of SO2 and NOx). Independently, co-injected O2 caused oxidation of pyrite, resulting in rapid increase in SO42- concentration during the first three days of the subsurface incubation. Subsequently, the SO42- concentration dropped in the back-produced water, which may be explained by SO42- adsorption on the surface of minerals like iron (oxyhydr)oxides and kaolinite or by reduced pyrite oxidation at distance from the well bore. Reactive transport modeling is currently underway to better understand the observations.

  7. 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.

  8. 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.

  9. Mineral impurities in coal combustion - behaviour, problems and remedial measures

    SciTech Connect

    Raask, E.

    1985-01-01

    Chapters cover the following topics: influence of coal mineral matter on boiler design; mineral impurities in coal; quality of coal utilized in power stations; coal grinding, abrasive fuel minerals and plant wear; particulate silicate minerals in boiler flame; reactions of nonsilicate impurities in coal flames; creation, capture and coalescence of particulate ash in boiler flame; slag viscosity; sintering, fusion and slagging propensities of coal ashes; adhesion of ash deposit on boiler tubes and refractory materials; deposition mechanisms, rate measurements and the mode of formation of boiler deposits; thermal radiation and heat transfer properties of boiler deposits; measures to combat boiler fouling and slagging; some specific ash-related problems with U.S. coals; use of additives in coal-fired boilers; high temperature corrosion in coal-fired plants; ash impaction erosion wear; low temperature fouling and corrosion; and comparison of ash-related problems in pulverized fuel fired and other coal- fired systems.

  10. The beauty of impurities: Two revivals of Friedel's virtual bound-state concept

    NASA Astrophysics Data System (ADS)

    Georges, Antoine

    2016-03-01

    Jacques Friedel pioneered the theoretical study of impurities and magnetic impurities in metals. He discovered Friedel oscillations, introduced the concept of virtual bound-state, and demonstrated that the charge on the impurity is related to the scattering phase-shift at the Fermi level (Friedel sum-rule). After a brief review of some of these concepts, I describe how they proved useful in two new contexts. The first one concerns the Coulomb blockade in quantum dots, and its suppression by the Kondo effect. The second one is the dynamical mean-field theory of strong electronic correlations. xml:lang="fr"

  11. Calculation of cohesion and changes in electronic structure due to impurity segregation at boundaries in iron

    SciTech Connect

    Rez, P.; Alvarez, J.R.

    1999-11-12

    It is well known that impurities in iron which segregate to grain boundaries can dramatically change physical properties. Carbon and boron tend to increase ductility while phosphorus and sulfur lead to embrittlement. Cohesion at boundaries in iron can be understood by studying changes in the iron d states responsible for bonding. Since the effects are quite localized, relatively small systems can be used to model the electronic structure. Both FLAPW and LKKR calculations show that the average energy of the d band is lower for B and C impurities and higher for P and S impurities. These results are consistent with the macroscopic changes in cohesion.

  12. Separation, characterization, and quantitation of process-related substances of the anti-hypertensive drug doxazosin mesylate by reversed-phase LC with PDA and ESI-MS as detectors.

    PubMed

    Nageswara Rao, R; Nagaraju, D; Das, A K; Jena, Nivedita

    2007-02-01

    A simple and rapid reversed-phase liquid chromatography (LC) method with photodiode array (PDA) and electrospray ionization (ESI)-mass spectrometry (MS) as detectors was developed and validated to separate, identify, and quantitate the related substances of Doxazosin mesylate (DXZN) for monitoring the reactions involved during process development. The high-performance liquid chromatography profiles of related-substances of DXZN are used as fingerprints to follow the procedures used in the manufacturing units. The separation is accomplished on an Inertsil ODS-3 column with acetonitrile-ammonium acetate (10 mM, pH 4.0) as the mobile phase, using a gradient elution mode and monitoring the eluents by a photodiode array detector at 265 nm at ambient temperature. LC-ESI-MS-MS is used to identify the additional impurities formed during the synthesis. The identified impurities were synthesized and characterized by UV, Fourier transform-IR, 1H NMR, and MS data. The detection limits for the impurities are 0.74 - 4.14 x 10(-9) g, and the method is found to be suitable not only for the monitoring of synthetic reactions, but also for quality assurance of DXZN in bulk drugs and formulations.

  13. Albedo Drop on the Greenland Ice Sheet: Relative Impacts of Wet and Dry Snow Processes

    NASA Astrophysics Data System (ADS)

    Chen, J.; Polashenski, C.

    2014-12-01

    The energy balance of the Greenland Ice Sheet (GIS) is strongly impacted by changes in snow albedo. MODIS (Moderate Resolution Imaging Spectroradiometer) observations indicate that the GIS albedo has dropped since the early part of this century. We analyze data from the MODIS products MOD10A1 for broadband snow albedo and MOD09A1 for surface spectral reflectance since 2001 to better explain the physical mechanisms driving these changes. The MODIS products are filtered, and the data is masked using microwave-derived surface melt maps to isolate albedo changes due to dry snow processes from those driven by melt impacts. Results show that the majority of recent changes in the GIS albedo - even at high elevations - are driven by snow wetting rather than dry snow processes such as grain metamorphosis and aerosol impurity deposition. The spectral signature of the smaller changes occurring within dry snow areas suggests that grain metamorphosis dominates the albedo decline in these regions.

  14. EFFECT OF IMPURITIES ON THE PERFORMANCE OF A Pd-Ag DIFFUSER

    SciTech Connect

    Morgan, G.

    2010-12-16

    A commercially fabricated diffuser purchased from Johnson-Matthey, Inc. was evaluated for performance characterization testing at the Savannah River National Laboratory (SRNL). Different impurities are often present in the feed streams of the process diffusers, but the effect of these impurities on the diffuser performance is currently unknown. Various impurities were introduced into the feed stream of the diffuser at various levels ranging from 0.5% to 10% of the total flow in order to determine the effect that these impurities have on the permeation of hydrogen through the palladium-silver membrane. The introduction of various impurities into the feed stream of the diffuser had a minimal effect on the overall permeation of hydrogen through the Pd-Ag membrane. Of the four impurities introduced into the feed stream, carbon monoxide (CO) was the only impurity that showed any evidence of causing a reduction in the amount of hydrogen permeating through the Pd-Ag membrane. The hydrogen permeation returned to its baseline level after the CO was removed from the feed stream. There were no lasting effects of the CO exposure on the ability of the membrane to effectively separate hydrogen from the non-hydrogen species in the gas stream under the conditions tested.

  15. Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities.

    PubMed

    Jung, Han Sae; Tsai, Hsin-Zon; Wong, Dillon; Germany, Chad; Kahn, Salman; Kim, Youngkyou; Aikawa, Andrew S; Desai, Dhruv K; Rodgers, Griffin F; Bradley, Aaron J; Velasco, Jairo; Watanabe, Kenji; Taniguchi, Takashi; Wang, Feng; Zettl, Alex; Crommie, Michael F

    2015-01-01

    Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees of freedom to control electronic devices. In particular, the behavior of graphene's charge carriers in response to potentials from charged Coulomb impurities is predicted to differ significantly from that of most materials. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) can provide detailed information on both the spatial and energy dependence of graphene's electronic structure in the presence of a charged impurity. The design of a hybrid impurity-graphene device, fabricated using controlled deposition of impurities onto a back-gated graphene surface, has enabled several novel methods for controllably tuning graphene's electronic properties. Electrostatic gating enables control of the charge carrier density in graphene and the ability to reversibly tune the charge and/or molecular states of an impurity. This paper outlines the process of fabricating a gate-tunable graphene device decorated with individual Coulomb impurities for combined STM/STS studies. These studies provide valuable insights into the underlying physics, as well as signposts for designing hybrid graphene devices. PMID:26273961

  16. Models for impurity effects in tokamaks

    SciTech Connect

    Hogan, J.T.

    1980-03-01

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

  17. 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)].

  18. 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.

  19. Hydrothermal Reaction of Silica Sand Contains Some Impurities with Lime

    NASA Astrophysics Data System (ADS)

    Watanabe, Osamu; Ishida, E. Hideki

    2006-05-01

    Tobermorite and xonotolite are the representative of calcium silicate materials and many studies have been made in the past regarding the methods of synthesis from relatively highly purified starting materials. From the point of preserving the global environment, procurement of pure raw materials for industrial use is likely to become difficult in the future, and the recycled use of various waste materials cannot be avoided. The hydrothermal reaction of slaked lime and silica sand containing feldspar and clay minerals as impurities have investigated. It was found that the flexural strength of the solidified bodies increased with increasing treatment temperature and treatment time, reaching values of up to 20MPa which was enough for building material and was proportional to the amount of reaction products but independent of their type. Hydrogarnet and C-S-H were formed in the initial stages of reaction and the amount of these phases tended to decrease and 1.1 nm tobermorite formed as the reaction progressed further. This indicates that hydrogarnet and C-S-H are precursors of 1.1 nm tobermorite. In this hydrothermal process, it was clarified that the reaction was controlled by the diffusion of Si fraction from kinetic study.

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

    PubMed

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

    2013-05-01

    The presence of impurities in biodegradable waste (biowaste) causes problems with the management of waste, among which are additional costs derived from the need to improve pre-treatment of biowaste, loss of treatment capacity and the difficulty selling treated biowaste as compost owing to its low quality. When treated biowaste is used for soil conditioning it can also cause soil pollution. Understanding the reasons why impurities are in biowaste and the factors affecting the percentage of impurities present can be used to determine ways to minimise these negative effects. This article attempts to identify the main causes for the presence of impurities in biowaste. In order to do so, it carries out an empirical analysis of the level of impurities in biowaste from municipal waste collection in two steps. First, a bivariate analysis focuses on significant correlations between the presence of impurities and several variables. Second, the construction of an explanatory model based on the significant relations obtained in the first step, and on literature research, are used to check the stated hypothesis. The estimates demonstrate that the collection system, the global levels of separate collection, the urban density of the municipality and the requirement to use compostable bags may be the main drivers of impurity levels in biowaste. PMID:23524997

  1. Perpetual motion and driven dynamics of a mobile impurity in a quantum fluid

    NASA Astrophysics Data System (ADS)

    Lychkovskiy, O.

    2015-04-01

    We study the dynamics of a mobile impurity in a quantum fluid at zero temperature. Two related settings are considered. In the first setting, the impurity is injected in the fluid with some initial velocity v0, and we are interested in its velocity at infinite time, v∞. We derive a rigorous upper bound on | v0-v∞| for initial velocities smaller than the generalized critical velocity. In the limit of vanishing impurity-fluid coupling, this bound amounts to v∞=v0 , which can be regarded as a rigorous proof of the Landau criterion of superfluidity. In the case of a finite coupling, the velocity of the impurity can drop, but not to zero; the bound quantifies the maximal possible drop. In the second setting, a small constant force is exerted upon the impurity. We argue that two distinct dynamical regimes exist—backscattering oscillations of the impurity velocity and saturation of the velocity without oscillations. For fluids with vc L=vs (where vc L and vs are the Landau critical velocity and sound velocity, respectively), the latter regime is realized. For fluids with vc Limpurity, a nonequilibrium quantum phase transition occurring at some critical mass. Our results are equally valid in one, two, and three dimensions.

  2. Characterization of Route Specific Impurities Found in Methamphetamine Synthesized by the Leuckart and Reductive Amination Methods

    PubMed Central

    2009-01-01

    Impurity profiling of seized methamphetamine can provide very useful information in criminal investigations and, specifically, on drug trafficking routes, sources of supply, and relationships between seizures. Particularly important is the identification of “route specific” impurities or those which indicate the synthetic method used for manufacture in illicit laboratories. Previous researchers have suggested impurities which are characteristic of the Leuckart and reductive amination (Al/Hg) methods of preparation. However, to date and importantly, these two synthetic methods have not been compared in a single study utilizing methamphetamine hydrochloride synthesized in-house and, therefore, of known synthetic origin. Using the same starting material, 1-phenyl-2-propanone (P2P), 40 batches of methamphetamine hydrochloride were synthesized by the Leuckart and reductive amination methods (20 batches per method). Both basic and acidic impurities were extracted separately and analyzed by GC/MS. From this controlled study, two route specific impurities for the Leuckart method and one route specific impurity for the reductive amination method are reported. The intra- and inter-batch variation of these route specific impurities was assessed. Also, the variation of the “target impurities” recently recommended for methamphetamine profiling is discussed in relation to their variation within and between production batches synthesized using the Leuckart and reductive amination routes. PMID:19637924

  3. A REVIEW OF RECENT IMPURITY MEASUREMENTS OF LANL MATERIAL

    SciTech Connect

    Edwards, T.

    2012-07-12

    The Applied Computational Engineering and Statistics (ACES) group of the Savannah River National Laboratory (SRNL) was asked to review recent measurements performed by the Los Alamos National Laboratory (LANL) on material from that facility that is being considered for processing through the Mixed Oxide (MOX) Fuel Fabrication Facility (MFFF) at the Savannah River Site (SRS). There are specification limits for impurities in the feed to the MOX facility: a maximum limit and an exceptional limit. The limits for an impurity apply to the population of concentration values for that impurity for a class of material that is to be processed through MOX. For the purposes of this report, these limits were defined as follows. The concentration of an elemental impurity, expressed as micrograms of the element per gram of plutonium ({micro}g/g Pu), is to be no more than the maximum limit for that element for 98% of the material coming through MOX; that is, 98% of the material processed at MOX is to have a concentration of the given element less than the maximum limit. In addition, the concentration for a given element is to be no more than the exceptional limit for that element for 99.9% of the material processed through MOX. The measurements evaluated as part of this study included LANL blend lots 1 through 29 and cover carbon (C), chlorine (Cl), fluorine (F), nitrogen (N), phosphorous (P), and sulfur (S). Note that all of the measurements for each impurity were below their respective maximum (and obviously, therefore, their exceptional) limits. Thus, there is no immediate concern regarding the LANL material being suitable for processing through MOX. Two approaches were used to investigate the quantiles of the impurity populations. The first approach used was a nonparametric approach. While the results from this approach did not indicate any problems for any of the impurities, there was too little data available to lead to confident statements about satisfying the maximum and

  4. Controlling the didactic relation: a case in process engineering education

    NASA Astrophysics Data System (ADS)

    Jaako, Juha

    2014-07-01

    A case study was conducted during 1994-2013 on several groups of process engineering students to see what was needed to transform a single course from a teacher-centred to a student-centred learning environment (SCLE). Development work was done incrementally, using Herbart's didactic triangle as a theoretical framework. The effects of the changes in learning environment were analysed using quantitative (student attendance, pass rate, attrition, grades) and qualitative data (student feedback). Guiding the didactic relation, i.e. the studying done by students, by continuous assessment was found to be very useful. Using SCLEs that emphasise student responsibility and activity in learning has been found in this case to enhance student learning considerably.

  5. Structures and processes: land, families, and gender relations.

    PubMed

    Jacobs, S

    1996-06-01

    The author points to the existence of a striking similarity in some of the effects of land reform upon gender relations and women's family positions. This is so despite the variation in land reform processes and in the cultures in which they occur. Family and kinship patterns both affect, and are affected by, land reform. This two-way relationship is examined, with particular attention given to the author's study of northeastern Zimbabwean Resettlement Areas, conducted during the mid-1980s, and Agarwal's 1994 study of women and land rights in South Asia. Sections discuss the effects of land reform; family formation, family relationships, and land; family and land in South Asia; reforms which disadvantage women; benefits for women of land reform; and the Zimbabwean case study.

  6. Aerial Refueling Process Rescheduling Under Job Related Disruptions

    NASA Technical Reports Server (NTRS)

    Kaplan, Sezgin; Rabadi, Ghaith

    2011-01-01

    The Aerial Refueling Scheduling Problem (ARSP) can be defined as determining the refueling completion times for each fighter aircraft (job) on the multiple tankers (machines) to minimize the total weighted tardiness. ARSP assumes that the jobs have different release times and due dates. The ARSP is dynamic environment and unexpected events may occur. In this paper, rescheduling in the aerial refueling process with a time set of jobs will be studied to deal with job related disruptions such as the arrival of new jobs, the departure of an existing job, high deviations in the release times and changes in job priorities. In order to keep the stability and to avoid excessive computation, partial schedule repair algorithm is developed and its preliminary results are presented.

  7. 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.

  8. 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.

  9. 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.

  10. Influence of surface silica impurities on the sintering behavior of alumina powders

    SciTech Connect

    Moya, J.S.; Pask, J.A.

    1980-02-01

    The filtering, pressing and sintering behavior of an alumina powder with and without silica impurity on surface has been studied. When silica is removed from surface by HF-treatment and compactibility is considerably enhanced due to the different acidity/basicity nature of the OH of the hydroxyl layers. The silica impurity decreases the activation energy of the initial stage of sintering and grain boundary energy, improves the densification process and exerts a moderate inhibitor effect on the grain growth.

  11. Emission of Polychlorinated Naphthalenes during Thermal Related Processes

    NASA Astrophysics Data System (ADS)

    Liu, Guorui; Zheng, Minghui; Du, Bing; Liu, Wenbin; Zhang, Bing; Xiao, Ke

    2010-05-01

    Due to the structural similarity of polychlorinated naphthalenes (PCNs) to those of dioxins, PCNs exhibit toxicological properties similar to dioxins (Olivero-Verbel et al., 2004). Based on their high toxicity, persistence, bioaccumulation, and long-distance transmission, PCNs were also selected as a candidate POP for the UN-ECE (United Nations Economic Commission for Europe) POP protocol (Lerche et al., 2002). In addition, some studies suggested that PCNs contributed a greater proportion of the dioxin-like activity than polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) contributed in some locations (Kannan et al., 1998). However, the identification and quantitation for PCN sources are very scarce compared with PCDD/Fs. Understanding the emission levels and developing the emission inventory of PCNs is important for regulatory and source reduction purposes. In this study, several potential sources were preliminarily investigated for PCN release. Coking process (CP), iron ore sintering (IOS), and electric arc furnace steel making units (AF) were selected due to their huge activity level of industrial production in China. Municipal solid waste incineration (MSWI) and medical waste incineration (MWI) were also investigated because of the possible high concentration of PCNs in stack gas. Two plants were investigated for each thermal related process, except for MWI with one incinerator was investigated. The stack gas samples were collected by automatic isokinetic sampling system (Isostack Basic, TCR TECORA, Milan Italy). Isotope dilution high resolution gas chromatography coupled with high resolution mass spectrometry (HRGC/HRMS) technique was used for the identification and quantitation of PCN congeners. The concentrations of PCNs from the selected thermal processes were determined in this study. The average concentrations of total PCNs were 26 ng Nm-3 for CP, 65 ng Nm-3 for IOS, 720 ng Nm-3 for AF, 443 ng Nm-3 for MSWI, and

  12. 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.

  13. Transport of Impurity Ions in the Wendelstein 7-AS Stellarator Plasma

    SciTech Connect

    Burhenn, Rainer; Baldzuhn, Juergen; Beidler, Craig; Brakel, Rudolf; Ehmler, Hartmut; Giannone, Louis; Grigull, Peter; Hirsch, Matthias; Knauer, Jens; Krychowiak, Maciej; Maassberg, Henning; McCormick, Kent; Pasch, Ekkehard; Weller, Arthur; Ida, Katsumi

    2006-01-15

    The impact of global plasma parameters on impurity transport in the stellarator W7-AS was investigated by laser blow-off technique. Both, density and heating power were identified to have a strong influence on impurity confinement {tau}{sub I} {approx} n{sub e}{sup 1.2}/P{sub ECRH}{sup 0.8}. In spite of stationary conditions at lower densities, an increasing trend for accumulation was observed at plasma densities beyond 5{center_dot}1019 m-3 due to reduction of the diffusion coefficients. Up to densities of at least 9{center_dot}1019 m-3, launching of electron cyclotron resonance heating (ECRH) power of 1.2 MW is able to counteract the impurity accumulation by deterioration of the impurity confinement with heating power according to the scaling law as given above. In neutral beam injection (NBI) heated plasmas at densities higher than 1{center_dot}1020m-3, long confinement times were observed, often accompanied by loss of density control and degradation of plasma energy due to increasing radiation losses. The installation of island divertor allowed a general extension of the range of accessible densities up to 4{center_dot}1020m-3: beyond a certain power-dependent threshold density (1.5-2.1{center_dot}1020m-3), the plasma enters the High Density H-mode (HDH) regime and the impurity confinement time drops to values comparable to the energy confinement time. High density plasmas could be sustained quasi-stationary with a low level of impurity radiation. The favourable impurity behavior goes along with a reduction of the inward impurity convection in the core plasma and possible changes in the edge transport. For the characterization of the general impurity behavior in W7-AS plasmas the usual transport models for axisymmetric devices are not sufficient and additional stellarator specific processes have to be considered.

  14. 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.

  15. Effect of copper impurity on polycrystalline silicon solar cells

    NASA Technical Reports Server (NTRS)

    Daud, T.; Koliwad, K. M.

    1978-01-01

    The presence of copper impurity, up to 10 to the 15th atoms/cc, in single crystal silicon has been shown to have no deleterious effect on the p-n junction solar cell performance. However, in polycrystalline silicon, copper atoms tend to migrate to the defect sites because of the structural sensitive properties of copper. This study was undertaken to investigate the influence of this behavior of copper impurity on the performance of p-n junction solar cells fabricated from structurally imperfect silicon. Two sets of polycrystalline silicon substrates containing copper were examined. In one set of samples, copper was incorporated during growth, whereas in the other, copper was diffused. Solar cells were fabricated on both the sets of substrates by a standard process. Dark and light I-V and spectral response characteristics of the cells were measured and compared with copper-free polycrystalline silicon solar cells. The results and the model are discussed.

  16. 23 CFR 636.109 - How does the NEPA process relate to the design-build procurement process?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... analysis and review process; complying with other related environmental laws and regulations; supporting... process and that the comparative merits of all alternatives presented in the NEPA document, including...

  17. 23 CFR 636.109 - How does the NEPA process relate to the design-build procurement process?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... analysis and review process; complying with other related environmental laws and regulations; supporting... process and that the comparative merits of all alternatives presented in the NEPA document, including...

  18. Isotope effects of trapped electron modes in the presence of impurities in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Shen, Yong; Dong, J. Q.; Sun, A. P.; Qu, H. P.; Lu, G. M.; He, Z. X.; He, H. D.; Wang, L. F.

    2016-04-01

    The trapped electron modes (TEMs) are numerically investigated in toroidal magnetized hydrogen, deuterium and tritium plasmas, taking into account the effects of impurity ions such as carbon, oxygen, helium, tungsten and others with positive and negative density gradients with the rigorous integral eigenmode equation. The effects of impurity ions on TEMs are investigated in detail. It is shown that impurity ions have substantially-destabilizing (stabilizing) effects on TEMs in isotope plasmas for {{L}ez}\\equiv {{L}ne}/{{L}nz}>0 (<0 ), opposite to the case of ion temperature gradient (ITG) driven modes. Detailed analyses of the isotope mass dependence for TEM turbulences in hydrogenic isotope plasmas with and without impurities are performed. The relations between the maximum growth rate of the TEMs with respect to the poloidal wave number and the ion mass number are given in the presence of the impurity ions. The results demonstrate that the maximum growth rates scale as {γ\\max}\\propto Mi-0.5 in pure hydrogenic plasmas. The scale depends on the sign of its density gradient and charge number when there is a second species of (impurity) ions. When impurity ions have density profiles peaking inwardly (i.e. {{L}ez}\\equiv {{L}ne}/{{L}nz}>0 ), the scaling also depends on ITG parameter {ηi} . The maximum growth rates scale as {γ\\max}\\propto M\\text{eff}-0.5 for the case without ITG ({ηi}=0 ) or the ITG parameter is positive ({ηi}>0 ) but the impurity ion charge number is low (Z≤slant 5.0 ). However, when {ηi}>0 and the impurity ion charge number is moderate (Z=6.0-8.0 ), the scaling law is found as {γ\\max}\\propto M\\text{eff}-1.0 . Here, Z is impurity ion charge number, and the effective mass number, {{M}\\text{eff}}=≤ft(1-{{f}z}\\right){{M}i}+{{f}z}{{M}z} , with {{M}i} and {{M}Z} being the mass numbers of the hydrogenic and impurity ions, respectively, and {{f}z}=Z{{n}0z}/{{n}0e} being the charge concentration of impurity ions. In addition, with regard

  19. On the formation of bromhexine impurity E and its chromatographic behaviour.

    PubMed

    Venhuis, B J; Weda, M; de Kaste, D; Lamme, E K

    2012-04-01

    An unknown bromhexine hydrochloride (BRH) degradation product in BRH oral solutions (finished products) was potentially related to the purity of this API. Several degradation experiments were conducted and its identity and formation were investigated using LC-DAD and LC-DAD-MS/MS. Using the LC method described in the Ph.Eur monograph BRH the degradation product was observed at RRTBRH 0.1 and the specified impurities A-D were ruled out as candidates. Impurity E was initially not considered as a candidate as EDQM reported an expected RRTBRH of 1.8. Still, the LC-DAD-MS/MS results were consistent with the M+ ion for impurity E and its expected fragment ions. Therefore, standard addition was carried out using the Ph. Eur. method which confirmed that the degradation product at RRT 0.1 was impurity E. Upon changing the column type to a column described in the knowledge database, impurity E eluted at an RRT of 1.5. Nevertheless, both columns met all of the criteria in the monograph. The formation of impurity E was even observed in BRH solutions without added reagents. As the conversion from BRH to impurity E requires a source of carbon, we suggest that one BRH molecule degrades through a radical mechanism to a reactive species which subsequently is quenched by another BRH molecule producing impurity E. We suggest the transparency list for BRH to be more explicit on the formation of impurity E, its RRT and the permissible LC columns. PMID:23327897

  20. Suppression of Impurity Back Scattering in Double Quantum Wires: Theory Beyond the Born Approximation

    SciTech Connect

    Huang, Danhong; Lyo, S.K.

    1999-08-09

    The effect of higher-order corrections to the Born approximation is studied for the previously obtained giant conductance enhancement in tunnel-coupled double quantum wires in a parallel magnetic field. The relative correction is found to be significant and depends on various effects such as the magnetic field, electron and impurity densities, impurity positions, symmetric and asymmetric doping profiles, and center barrier thickness.

  1. Primary task event-related potentials related to different aspects of information processing

    NASA Technical Reports Server (NTRS)

    Munson, Robert C.; Horst, Richard L.; Mahaffey, David L.

    1988-01-01

    The results of two studies which investigated the relationships between cognitive processing and components of transient event-related potentials (ERPs) are presented in a task in which mental workload was manipulated. The task involved the monitoring of an array of discrete readouts for values that went out of bounds, and was somewhat analogous to tasks performed in cockpits. The ERPs elicited by the changing readouts varied with the number of readouts being monitored, the number of monitored readouts that were close to going out of bounds, and whether or not the change took a monitored readout out of bounds. Moreover, different regions of the waveform differentially reflected these effects. The results confirm the sensitivity of scalp-recorded ERPs to the cognitive processes affected by mental workload and suggest the possibility of extracting useful ERP indices of primary task performance in a wide range of man-machine settings.

  2. Impurity trapped excitons under high hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Grinberg, Marek

    2013-09-01

    Paper summarizes the results on pressure effect on energies of the 4fn → 4fn and 4fn-15d1 → 4fn transitions as well as influence of pressure on anomalous luminescence in Lnα+ doped oxides and fluorides. A model of impurity trapped exciton (ITE) was developed. Two types of ITE were considered. The first where a hole is localized at the Lnα+ ion (creation of Ln(α+1)+) and an electron is attracted by Coulomb potential at Rydberg-like states and the second where an electron captured at the Lnα+ ion (creation of Ln(α-1)+) and a hole is attracted by Coulomb potential at Rydberg-like states. Paper presents detailed analysis of nonlinear changes of energy of anomalous luminescence of BaxSr1-xF2:Eu2+ (x > 0.3) and LiBaF3:Eu2+, and relate them to ITE-4f65d1 states mixing.

  3. Theory of the screened Coulomb field generated by impurity ions in semiconductors

    NASA Astrophysics Data System (ADS)

    Kwon, Young D.

    2006-04-01

    This theory examines the effect of the screened Coulomb field generated by impurity ions on various semiconductor phenomena. The exact equation for the screening length, which is derived for semiconductors, is a function of temperature, doping density and intrinsic carrier density. In silicon the screening length varies from a fraction of a nanometer to thousands of nanometers depending on the temperature and the doping density. The overlap of these impurity fields causes both crystal potential shift and repulsion among impurity ions. The repulsion among the impurity ions gives rise to a pressure build-up, which is attributed to such phenomena as solid solubility and diffusion-induced defect generation. The experimental solubilities of lithium in germanium, and boron, phosphorus, and arsenic in silicon are compared with the theoretical values. Also, the optically enhanced solubility during rapid thermal processing is explained.

  4. Photoluminescence imaging of electronic-impurity-induced exciton quenching in single-walled carbon nanotubes.

    PubMed

    Crochet, Jared J; Duque, Juan G; Werner, James H; Doorn, Stephen K

    2012-02-01

    The electronic properties of single-walled carbon nanotubes can be altered by surface adsorption of electronic impurities or dopants. However, fully understanding the influence of these impurities is difficult because of the inherent complexity of the solution-based colloidal chemistry of nanotubes, and because of a lack of techniques for directly imaging dynamic processes involving these impurities. Here, we show that photoluminescence microscopy can be used to image exciton quenching in semiconducting single-walled carbon nanotubes during the early stages of chemical doping with two different species. The addition of AuCl(3) leads to localized exciton-quenching sites, which are attributed to a mid-gap electronic impurity level, and the adsorbed species are also found sometimes to be mobile on the surface of the nanotubes. The addition of H(2)O(2) leads to delocalized exciton-quenching hole states, which are responsible for long-range photoluminescence blinking, and are also mobile.

  5. Classification of illicit heroin by UPLC-Q-TOF analysis of acidic and neutral manufacturing impurities.

    PubMed

    Liu, Cuimei; Hua, Zhendong; Bai, Yanping

    2015-12-01

    The illicit manufacture of heroin results in the formation of trace levels of acidic and neutral manufacturing impurities that provide valuable information about the manufacturing process used. In this work, a new ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF) method; that features high resolution, mass accuracy and sensitivity for profiling neutral and acidic heroin manufacturing impurities was developed. After the UPLC-Q-TOF analysis, the retention times and m/z data pairs of acidic and neutral manufacturing impurities were detected, and 19 peaks were found to be evidently different between heroin samples from "Golden Triangle" and "Golden Crescent". Based on the data set of these 19 impurities in 150 authentic heroin samples, classification of heroin geographic origins was successfully achieved utilizing partial least squares discriminant analysis (PLS-DA). By analyzing another data set of 267 authentic heroin samples, the developed discrimiant model was validated and proved to be accurate and reliable.

  6. Reduced emotion processing efficiency in healthy males relative to females.

    PubMed

    Weisenbach, Sara L; Rapport, Lisa J; Briceno, Emily M; Haase, Brennan D; Vederman, Aaron C; Bieliauskas, Linas A; Welsh, Robert C; Starkman, Monica N; McInnis, Melvin G; Zubieta, Jon-Kar; Langenecker, Scott A

    2014-03-01

    This study examined sex differences in categorization of facial emotions and activation of brain regions supportive of those classifications. In Experiment 1, performance on the Facial Emotion Perception Test (FEPT) was examined among 75 healthy females and 63 healthy males. Females were more accurate in the categorization of fearful expressions relative to males. In Experiment 2, 3T functional magnetic resonance imaging data were acquired for a separate sample of 21 healthy females and 17 healthy males while performing the FEPT. Activation to neutral facial expressions was subtracted from activation to sad, angry, fearful and happy facial expressions. Although females and males demonstrated activation in some overlapping regions for all emotions, many regions were exclusive to females or males. For anger, sad and happy, males displayed a larger extent of activation than did females, and greater height of activation was detected in diffuse cortical and subcortical regions. For fear, males displayed greater activation than females only in right postcentral gyri. With one exception in females, performance was not associated with activation. Results suggest that females and males process emotions using different neural pathways, and these differences cannot be explained by performance variations.

  7. Reduced emotion processing efficiency in healthy males relative to females

    PubMed Central

    Rapport, Lisa J.; Briceno, Emily M.; Haase, Brennan D.; Vederman, Aaron C.; Bieliauskas, Linas A.; Welsh, Robert C.; Starkman, Monica N.; McInnis, Melvin G.; Zubieta, Jon-Kar; Langenecker, Scott A.

    2014-01-01

    This study examined sex differences in categorization of facial emotions and activation of brain regions supportive of those classifications. In Experiment 1, performance on the Facial Emotion Perception Test (FEPT) was examined among 75 healthy females and 63 healthy males. Females were more accurate in the categorization of fearful expressions relative to males. In Experiment 2, 3T functional magnetic resonance imaging data were acquired for a separate sample of 21 healthy females and 17 healthy males while performing the FEPT. Activation to neutral facial expressions was subtracted from activation to sad, angry, fearful and happy facial expressions. Although females and males demonstrated activation in some overlapping regions for all emotions, many regions were exclusive to females or males. For anger, sad and happy, males displayed a larger extent of activation than did females, and greater height of activation was detected in diffuse cortical and subcortical regions. For fear, males displayed greater activation than females only in right postcentral gyri. With one exception in females, performance was not associated with activation. Results suggest that females and males process emotions using different neural pathways, and these differences cannot be explained by performance variations. PMID:23196633

  8. Gender differences in reward-related decision processing under stress

    PubMed Central

    Sakaki, Michiko; Vasunilashorn, Sarinnapha; Nga, Lin; Somayajula, Sangeetha; Chen, Eric Y.; Samii, Nicole; Mather, Mara

    2012-01-01

    Recent research indicates gender differences in the impact of stress on decision behavior, but little is known about the brain mechanisms involved in these gender-specific stress effects. The current study used functional magnetic resonance imaging (fMRI) to determine whether induced stress resulted in gender-specific patterns of brain activation during a decision task involving monetary reward. Specifically, we manipulated physiological stress levels using a cold pressor task, prior to a risky decision making task. Healthy men (n = 24, 12 stressed) and women (n = 23, 11 stressed) completed the decision task after either cold pressor stress or a control task during the period of cortisol response to the cold pressor. Gender differences in behavior were present in stressed participants but not controls, such that stress led to greater reward collection and faster decision speed in males but less reward collection and slower decision speed in females. A gender-by-stress interaction was observed for the dorsal striatum and anterior insula. With cold stress, activation in these regions was increased in males but decreased in females. The findings of this study indicate that the impact of stress on reward-related decision processing differs depending on gender. PMID:21609968

  9. Impurity Profiling to Match a Nerve Agent to Its Precursor Source for Chemical Forensics Applications

    SciTech Connect

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

    2011-10-31

    Chemical forensics is an emerging field in homeland security that aims to attribute a weaponized toxic chemical or related material to its source. Herein, for the first time, trace impurities originating from a chemical precursor were used to match a synthesized nerve agent to its precursor source. Specifically, multiple batches of sarin and its intermediate were synthesized from two commercial stocks of methylphosphonic dichloride (DC) and were then matched by impurity profiling to their DC stocks from out of five possible stocks. This was possible because each DC stock had a unique impurity profile that, for the tested stocks, persisted through synthesis, decontamination, and sample preparation. This work may form a basis for using impurity profiling to help find and prosecute perpetrators of chemical attacks.

  10. Animacy in Processing Relative Clauses: The Hikers that Rocks Crush

    ERIC Educational Resources Information Center

    Mak, Willem M.; Vonk, Wietske; Schriefers, Herbert

    2006-01-01

    For several languages, a preference for subject relative clauses over object relative clauses has been reported. However, Mak, Vonk, and Schriefers (2002) showed that there is no such preference for relative clauses with an animate subject and an inanimate object. A Dutch object relative clause as...de rots, die de wandelaars beklommen hebben...…

  11. Metal impurity-assisted formation of nanocone arrays on Si by low energy ion-beam irradiation

    NASA Astrophysics Data System (ADS)

    Steeves Lloyd, Kayla; Bolotin, Igor L.; Schmeling, Martina; Hanley, Luke; Veryovkin, Igor V.

    2016-10-01

    Fabrication of nanocone arrays on Si surfaces was demonstrated using grazing incidence irradiation with 1 keV Ar+ ions concurrently sputtering the surface and depositing metal impurity atoms on it. Among three materials compared as co-sputtering targets Si, Cu and stainless steel, only steel was found to assist the growth of dense arrays of nanocones at ion fluences between 1018 and 1019 ions/cm2. The structural characterization of samples irradiated with these ion fluences using Scanning Electron Microscopy and Atomic Force Microscopy revealed that regions far away from co-sputtering targets are covered with nanoripples, and that nanocones popped-up out of the rippled surfaces when moving closer to co-sputtering targets, with their density gradually increasing and reaching saturation in the regions close to these targets. The characterization of the samples' chemical composition with Total Reflection X-ray Fluorescence Spectrometry and X-ray Photoelectron Spectroscopy revealed that the concentration of metal impurities originating from stainless steel (Fe, Cr and Ni) was relatively high in the regions with high density of nanocones (Fe reaching a few atomic percent) and much lower (factor of 10 or so) in the region of nanoripples. Total Reflection X-ray Fluorescence Spectrometry measurements showed that higher concentrations of these impurities are accumulated under the surface in both regions. X-ray Photoelectron Spectroscopy experiments showed no direct evidence of metal silicide formation occurring on one region only (nanocones or nanoripples) and thus showed that this process could not be the driver of nanocone array formation. Also, these measurements indicated enhancement in oxide formation on regions covered by nanocones. Overall, the results of this study suggest that the difference in concentration of metal impurities in the thin near-surface layer forming under ion irradiation might be responsible for the differences in surface structures.

  12. Effects of O{sub 3} and H{sub 2}O oxidants on C and N-related impurities in atomic-layer-deposited La{sub 2}O{sub 3} films observed by in situ x-ray photoelectron spectroscopy

    SciTech Connect

    Park, Tae Joo; Sivasubramani, Prasanna; Coss, Brian E.; Kim, Hyun-Chul; Lee, Bongki; Wallace, Robert M.; Kim, Jiyoung; Rousseau, Mike; Liu Xinye; Li Huazhi; Lehn, Jean-Sebastien; Hong, Daewon; Shenai, Deo

    2010-08-30

    The effect of H{sub 2}O and O{sub 3} oxidants on the behavior of residual C and N-related impurities as well as Si out-diffusion and interfacial layer formation in atomic-layer-deposited La{sub 2}O{sub 3} films grown at 250 deg. C were examined using in situ x-ray photoelectron spectroscopy. The silicate formation was suppressed in a La{sub 2}O{sub 3} film grown using O{sub 3} compared to that deposited using H{sub 2}O, but interfacial layer growth was enhanced. The accumulation of C and N-related residues with low binding energy, which originated from incomplete reactions, was suppressed in La{sub 2}O{sub 3} films grown using O{sub 3}. However, the use of O{sub 3} resulted in La-carbonate phase in film.

  13. 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.

  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. Satellite Water Impurity Marker (SWIM) for predicting seasonal cholera outbreaks

    NASA Astrophysics Data System (ADS)

    Jutla, A. S.; Akanda, A. S.; Islam, S.

    2011-12-01

    Prediction of outbreaks of cholera, a deadly water related disease, remains elusive. Since coastal brackish water provides a natural ecological niche for cholera bacteria and because a powerful evidence of new biotypes is emerging, it is highly unlikely that cholera will be fully eradicated. Therefore, it is necessary to develop cholera prediction model with several months' of lead time. Satellite based estimates of chlorophyll, a surrogate for phytoplankton abundance, has been associated with proliferation of cholera bacteria. However, survival of cholera bacteria in a variety of coastal ecological environment put constraints on predictive abilities of chlorophyll algorithm since it only measures greenness in coastal waters. Here, we propose a new remote sensing reflectance based statistical index: Satellite Water Impurity Marker, or SWIM. This statistical index estimates impurity levels in the coastal waters and is based on the variability observed in the difference between the blue (412nm) and green (555nm) wavelengths in coastal waters. The developed index is bounded between clear and impure water and shows the ability to predict cholera outbreaks in the Bengal Delta with a predicted r2 of 78% with two months lead time. We anticipate that a predictive system based on SWIM will provide essential lead time allowing effective intervention and mitigation strategies to be developed for other cholera endemic regions of the world.

  16. Quantum Monte Carlo study of magnetic impurity in bilayer grephene

    NASA Astrophysics Data System (ADS)

    Sun, J. H.; Hu, F. M.; Tang, H. K.; Lin, Hai-Qing

    2012-02-01

    It is expected to observe many different properties in bilayer graphene when compared with single layer graphene due to the differences in crystal structure. Additionally, bilayer system offers a freedom of inducing a gap in the energy band by applying a shift in the electrochemical potential to two graphene layers. In this work, we study the magnetic properties of an Anderson magnetic adatom in Bernal stacking bilayer graphene and compare the results with those of single layer counterpart. Several different cases such as different adatom position and different potential bias of two layers are studied using the quantum Monte Carlo method. In all the cases, we find that the impurity local magnetic moment can be switched between relatively large and small values by tuning the chemical potential. We apply MaxEnT method to compute impurity spectral density and find its behavior to differ from that of an impurity in a single layer graphene. We also calculate various correlation functions and make comparisons.

  17. Scandium resonant impurity level in PbTe

    SciTech Connect

    Skipetrov, E. P. Skipetrova, L. A.; Knotko, A. V.; Slynko, E. I.; Slynko, V. E.

    2014-04-07

    We synthesize a scandium-doped PbTe single-crystal ingot and investigate the phase and the elemental composition as well as galvanomagnetic properties of Pb{sub 1-y}Sc{sub y}Te alloys in weak magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) upon varying the scandium content (y ≤ 0.02). We find that all investigated samples are single-phase and n-type. The distribution of scandium impurities along the axis of the ingot is estimated to be exponential. An increase of scandium impurity content leads to a monotonous growth of the free electron concentration by four orders of magnitude (approximately from 10{sup 16} cm{sup −3} to 10{sup 20} cm{sup −3}). In heavily doped alloys (y > 0.01), the free electron concentration at the liquid-helium temperature tends to saturation, indicating the pinning of the Fermi energy by the scandium resonant impurity level located on the background of the conduction band. Using the two-band Kane and six-band Dimmock dispersion relations for IV-VI semiconductors, dependences of the Fermi energy measured from the bottom of the conduction band E{sub c} on the scandium impurity content are calculated and the energy of the resonant scandium level is estimated to be E{sub Sc} ≈ E{sub c} + 280 meV. Diagrams of electronic structure rearrangement of Pb{sub 1-y}Sc{sub y}Te alloys upon doping are proposed.

  18. Characterization of impurities deposited on the PDX graphite rail limiter

    SciTech Connect

    Doyle, B.L.; Wampler, W.R.; Dylla, H.F.; Owens, D.K.; Ulrickson, M.L.

    1984-05-01

    The surface contamination of a graphite rail limiter recently removed from the PDX tokamak has been characterized using ion-beam, electron-beam and x-ray analyses. The major impurities detected were Ti and Fe, with the Ti present in the form of a carbide. The distribution of these elements indicate that the erosion and deposition processes balance at a distance one cm from the apex of this limiter (the point of contact with the plasma) for Ti and at about two cm for Fe. The importance of TiC formation on the conditioning process is discussed.

  19. Characterization of impurities deposited on the PDX graphite rail limiter

    NASA Astrophysics Data System (ADS)

    Doyle, B. L.; Wampler, W. R.; Dylla, H. F.; Owens, D. K.; Ulrickson, M. L.

    1984-12-01

    The surface contamination of a graphite rail limiter recently removed from the PDX tokamak has been characterized using ion-beam, electron-beam and X-ray analyses. The major impurities detected were Ti and Fe, with the Ti present in the form of a carbide. The distribution of these elements indicate that the erosion and deposition processes balance at a distance one cm from the apex of this limiter (the point of contact with the plasma) for Ti and at about two cm for Fe. The importance of TiC formation on the conditioning process is discussed.

  20. Characterization of impurities deposited on the PDX graphite rail limiter

    SciTech Connect

    Doyle, B.L.; Wampler, W.R.; Dylla, H.F.; Owens, D.K.; Ulrickson, M.L.

    1984-09-01

    The surface contamination of a graphite rail limiter recently removed from the PDX tokamak has been characterized using ion-beam, electron-beam and x-ray analyses. The major impurities detected were Ti and Fe, with the Ti present in the form of a carbide. The distribution of these elements indicate that the erosion and deposition processes balance at a distance one cm from the apex of this limiter (the point of contact with the plasma) for Ti and at about two cm for Fe. The importance of TiC formation on the conditioning process is discussed.

  1. 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

  2. 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.

  3. Interstitial iron impurities at grain boundaries in silicon: A first-principles study

    NASA Astrophysics Data System (ADS)

    Ziebarth, Benedikt; Mrovec, Matous; Elsässer, Christian; Gumbsch, Peter

    2015-01-01

    Iron impurities have a negative effect on the efficiency of silicon-based solar cells because they act as trapping centers for charge carriers. Various processing techniques have been applied to improve the efficiency by passivating the Fe contaminants. For instance, internal gettering exploits the attractive interaction between interfaces and the diffusing Fe atoms. Therefore, it is interesting and important to develop a fundamental understanding of mechanisms for this interaction. In this work, we employ density functional theory to study the electronic structure and the segregation behavior of impurity atoms at grain boundaries (GBs). The investigated set of symmetrical tilt or twist GBs in Si provides a variety of interface orientations and structures at the atomic scale. Our results suggest that segregation of interstitial Fe occurs only at specific sites at some of these GBs, e.g., the Σ 3 (112) GBs and Σ 3 (110) GBs. However, there seems to be no obvious relation between the computed segregation energies and the local coordination and electronic structure at the segregation sites. Hence, the thermodynamics of interstitial Fe at GBs in Si is determined by rather subtle features of structure and bonding.

  4. 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.

  5. 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.

  6. The excited state dynamics of KLa(MoO{sub 4}){sub 2}:Pr{sup 3+}: From a case study to the determination of the energy levels of rare earth impurities relative to the bandgap in oxidising host lattices

    SciTech Connect

    Cavalli, Enrico Boutinaud, Philippe; Bettinelli, Marco; Dorenbos, Pieter

    2008-05-15

    The luminescence properties of KLa(MoO{sub 4}){sub 2} (KLM) single crystals doped with Pr{sup 3+} have been measured in the 10-600 K temperature range in order to investigate the mechanisms involved in the radiationless processes. At variance with previously studied scheelite-like molybdates activated with Pr{sup 3+}, no effects attributed to the formation of intervalence charge transfer states have been observed. The model proposed in order to account for this behaviour allows the determination of the energy of the Pr{sup 3+} levels relative to the valence and conduction bands of the host. This model has firstly been confirmed for Tb{sup 3+}-doped KLM, for which suitable experimental data are available, and then extended to the other rare earth ions on the basis of the systematic nature of the lanthanide energy levels properties. The obtained conclusions are finally supported in the light of the comparison with some other representative cases. - Graphical abstract: The study of the excited state dynamics of KLa(MoO{sub 4}){sub 2} single crystals doped with Pr{sup 3+} allows to determine the energies of the levels of the active ion relative to the valence and conduction bands of the host. This model has then been extended to the other rare earth ions on the basis of the systematic nature of the lanthanide energy levels properties.

  7. Model for the catalytic oxidation of CO, including gas-phase impurities and CO desorption

    NASA Astrophysics Data System (ADS)

    Buendía, G. M.; Rikvold, P. A.

    2013-07-01

    We present results of kinetic Monte Carlo simulations of a modified Ziff-Gulari-Barshad model for the reaction CO+O → CO2 on a catalytic surface. Our model includes impurities in the gas phase, CO desorption, and a modification known to eliminate the unphysical O poisoned phase. The impurities can adsorb and desorb on the surface, but otherwise remain inert. In a previous work that did not include CO desorption [Buendía and Rikvold, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.85.031143 85, 031143 (2012)], we found that the impurities have very distinctive effects on the phase diagram and greatly diminish the reactivity of the system. If the impurities do not desorb, once the system reaches a stationary state, the CO2 production disappears. When the impurities are allowed to desorb, there are regions where the CO2 reaction window reappears, although greatly reduced. Following experimental evidence that indicates that temperature effects are crucial in many catalytic processes, here we further analyze these effects by including a CO desorption rate. We find that the CO desorption has the effect to smooth the transition between the reactive and the CO rich phase, and most importantly it can counteract the negative effects of the presence of impurities by widening the reactive window such that now the system remains catalytically active in the whole range of CO pressures.

  8. Relational operants: processes and implications: a response to Palmer's review of Relational Frame Theory.

    PubMed

    Hayes, Steven C; Barnes-Holmes, Dermot

    2004-09-01

    Palmer has recently criticized Relational Frame Theory (RFT) on the grounds that it has developed data in search of a principle. In this reply, we show that he has done so by attacking fundamental concepts within behavior analysis itself, including the functional nature of an operant and contingencies of reinforcement as a behavioral process. His claim that RFT appeals to new behavioral principles to explain the development of relational operants is shown to be incorrect: As with any operant, RFT appeals to a history of contacted consistencies in contingencies across multiple ex-emplars to explain them. New principles only emerge later as a logically necessary extension of such operants if they exist--a view that Palmer failed to address or appreciate. Palmer's desire to see the use of methods other than matching-to-sample is proper but already largely satisfied in the empirical literature on RFT. We show Palmer's defense of Skinner's definition of verbal behavior to be illogical and unresponsive to the empirical challenge behavior analysis faces. Palmer's alternative common sense mediational associationistic account is another in more than a century of such accounts, all of which have failed empirically. At its root, Palmer's criticism is based on a mechanistic philosophy that is hostile to a traditional functional behavior analytic approach. PMID:15540506

  9. Relational operants: processes and implications: a response to Palmer's review of Relational Frame Theory.

    PubMed

    Hayes, Steven C; Barnes-Holmes, Dermot

    2004-09-01

    Palmer has recently criticized Relational Frame Theory (RFT) on the grounds that it has developed data in search of a principle. In this reply, we show that he has done so by attacking fundamental concepts within behavior analysis itself, including the functional nature of an operant and contingencies of reinforcement as a behavioral process. His claim that RFT appeals to new behavioral principles to explain the development of relational operants is shown to be incorrect: As with any operant, RFT appeals to a history of contacted consistencies in contingencies across multiple ex-emplars to explain them. New principles only emerge later as a logically necessary extension of such operants if they exist--a view that Palmer failed to address or appreciate. Palmer's desire to see the use of methods other than matching-to-sample is proper but already largely satisfied in the empirical literature on RFT. We show Palmer's defense of Skinner's definition of verbal behavior to be illogical and unresponsive to the empirical challenge behavior analysis faces. Palmer's alternative common sense mediational associationistic account is another in more than a century of such accounts, all of which have failed empirically. At its root, Palmer's criticism is based on a mechanistic philosophy that is hostile to a traditional functional behavior analytic approach.

  10. Relational operants: processes and implications: a response to Palmer's review of Relational Frame Theory.

    PubMed Central

    Hayes, Steven C; Barnes-Holmes, Dermot

    2004-01-01

    Palmer has recently criticized Relational Frame Theory (RFT) on the grounds that it has developed data in search of a principle. In this reply, we show that he has done so by attacking fundamental concepts within behavior analysis itself, including the functional nature of an operant and contingencies of reinforcement as a behavioral process. His claim that RFT appeals to new behavioral principles to explain the development of relational operants is shown to be incorrect: As with any operant, RFT appeals to a history of contacted consistencies in contingencies across multiple ex-emplars to explain them. New principles only emerge later as a logically necessary extension of such operants if they exist--a view that Palmer failed to address or appreciate. Palmer's desire to see the use of methods other than matching-to-sample is proper but already largely satisfied in the empirical literature on RFT. We show Palmer's defense of Skinner's definition of verbal behavior to be illogical and unresponsive to the empirical challenge behavior analysis faces. Palmer's alternative common sense mediational associationistic account is another in more than a century of such accounts, all of which have failed empirically. At its root, Palmer's criticism is based on a mechanistic philosophy that is hostile to a traditional functional behavior analytic approach. PMID:15540506

  11. Undercompensated kondo impurity with quantum critical point

    PubMed

    Schlottmann

    2000-02-14

    The low-temperature properties of a magnetic impurity of spin S interacting with an electron gas via anisotropic spin exchange are studied via Bethe's ansatz. For S>1/2 the impurity is only partially compensated at T = 0, leaving an effective spin that is neither integer nor half integer. The entropy has an essential singularity at H = T = 0, and the susceptibility and the specific heat follow power laws of H and T with nonuniversal exponents, which are the consequence of a quantum critical point. The results for the generalization to an arbitrary number of channels are also reported. PMID:11017567

  12. 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.

  13. Are Auditory and Visual Processing Deficits Related to Developmental Dyslexia?

    ERIC Educational Resources Information Center

    Georgiou, George K.; Papadopoulos, Timothy C.; Zarouna, Elena; Parrila, Rauno

    2012-01-01

    The purpose of this study was to examine if children with dyslexia learning to read a consistent orthography (Greek) experience auditory and visual processing deficits and if these deficits are associated with phonological awareness, rapid naming speed and orthographic processing. We administered measures of general cognitive ability, phonological…

  14. Task Related Modulation of the Motor System during Language Processing

    ERIC Educational Resources Information Center

    Sato, Marc; Mengarelli, Marisa; Riggio, Lucia; Gallese, Vittorio; Buccino, Giovanni

    2008-01-01

    Recent neurophysiological and brain imaging studies have shown that the motor system is involved in language processing. However, it is an open question whether this involvement is a necessary requisite to understand language or rather a side effect of distinct cognitive processes underlying it. In order to clarify this issue we carried out three…

  15. On the Law Relating Processing to Storage in Working Memory

    ERIC Educational Resources Information Center

    Barrouillet, Pierre; Portrat, Sophie; Camos, Valerie

    2011-01-01

    "Working memory" is usually defined in cognitive psychology as a system devoted to the simultaneous processing and maintenance of information. However, although many models of working memory have been put forward during the last decades, they often leave underspecified the dynamic interplay between processing and storage. Moreover, the account of…

  16. "Getting the Point" of Literature: Relations between Processing and Interpretation

    ERIC Educational Resources Information Center

    Burkett, Candice; Goldman, Susan R.

    2016-01-01

    Comparisons of literary experts and novices indicate that experts engage in interpretive processes to "get the point" during their reading of literary texts but novices do not. In two studies the reading and interpretive processes of literary novices (undergraduates with no formal training in literature study) were elicited through…

  17. The origin of deep-level impurity transitions in hexagonal boron nitride

    SciTech Connect

    Du, X. Z.; Li, J.; Lin, J. Y.; Jiang, H. X.

    2015-01-12

    Deep ultraviolet photoluminescence (PL) emission spectroscopy has been employed to investigate the origin of the widely observed deep level impurity related donor-acceptor pair (DAP) transition with an emission peak near 4.1 eV in hexagonal boron nitride (h-BN). A set of h-BN epilayers were grown by metal-organic chemical vapor deposition (MOCVD) under different ammonia (NH{sub 3}) flow rates to explore the role of nitrogen vacancies (V{sub N}) in the deep-level transitions. The emission intensity of the DAP transition near 4.1 eV was found to decrease exponentially with an increase of the NH{sub 3} flow rate employed during the MOCVD growth, implying that impurities involved are V{sub N}. The temperature-dependent PL spectra were measured from 10 K up to 800 K, which provided activation energies of ∼0.1 eV for the shallow impurity. Based on the measured energy level of the shallow impurity (∼0.1 eV) and previously estimated bandgap value of about 6.5 eV for h-BN, we deduce a value of ∼2.3 eV for the deep impurity involved in this DAP transition. The measured energy levels together with calculation results and formation energies of the impurities and defects in h-BN suggest that V{sub N} and carbon impurities occupying the nitrogen sites, respectively, are the most probable shallow donor and deep acceptor impurities involved in this DAP transition.

  18. 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.

  19. Some aspects of selection of impurities improving photoelectric characteristics of chalcogenide vitreous semiconductors

    SciTech Connect

    Burdiyan, I. I.; Cosiuc, V. V. Pynzar', R. A.

    2008-02-15

    The effect of low concentrations of two groups of doping impurities (one group includes Sn, Pb, Dy, Ho, Y and the other group includes In, Cs, and Al) on photoelectric properties of As{sub 2}Se{sub 3} and (As{sub 2}S{sub 3}){sub 0.3}(As{sub 2}Se{sub 3}){sub 0.7} was investigated. Studies of spectral distributions of photoconductivity and optical absorption showed that there is a distinct increase in photoconductivity if the level of doping with elements of the first group is as high as 0.015%. Elements of the second group of impurities did not exert any significant effect on photoconductivity. The effect of impurities of the first group is attributed to occupation of vacant sites (formed as a result of removal of highly volatile Se and S atoms) by low concentrations of impurity atoms. The observed effect is related to the fact that substitutional atoms can preserve covalent bonds and to the small difference between atomic sizes and electron affinity for doping impurities and S and Se. Atoms of the second group of impurities lack these features.

  20. Periodic trends governing the interactions between impurity atoms [H-Ar] and (alpha)-U

    SciTech Connect

    Taylor, Christopher David

    2008-01-01

    The binding energies, geometries, charges and electronic structures of a series of impurity atoms [H-Ar] interacting with the {alpha}-U lattice in various configurations were assessed by means of density functional theory calculations. Periodic trends governing the binding energy were highlighted and related to the electronic properties of the impurity atoms, with some consideration given to the band-structure of {alpha}-U. The strongest bound impurity atoms include [C, N, O] and [Si, P, S]. The general trends in the binding energy can be reproduced by a simple parameterisation in terms of the electronegativity (charge-transfer) and covalent radius (elasticity theory) of the impurity atom. The strongest bound atoms deviate from this model, due to their ability to bind with an optimum mixture of covalency and ionicity. This last point is evidenced by the partial overlap of the impurity atom p-band with the hybrid d-/f-band of {alpha}-U. It is expected that the trends and general behaviour reported in this work can be extended to the interactions of impurity atoms with other metallic systems.

  1. Impurity profiling of trinitrotoluene using vacuum-outlet gas chromatography-mass spectrometry.

    PubMed

    Brust, Hanneke; Willemse, Sander; Zeng, Tuoyu; van Asten, Arian; Koeberg, Mattijs; van der Heijden, Antoine; Bolck, Annabel; Schoenmakers, Peter

    2014-12-29

    In this work, a reliable and robust vacuum-outlet gas chromatography-mass spectrometry (GC-MS) method is introduced for the identification and quantification of impurities in trinitrotoluene (TNT). Vacuum-outlet GC-MS allows for short analysis times; the analysis of impurities in TNT was performed in 4min. This study shows that impurity profiling of TNT can be used to investigate relations between TNT samples encountered in forensic casework. A wide variety of TNT samples were analyzed with the developed method. Dinitrobenzene, dinitrotoluene, trinitrotoluene and amino-dinitrotoluene isomers were detected at very low levels (<1wt.%) by applying the MS in selected-ion monitoring (SIM) mode. Limits of detection ranged from 6ng/mL for 2,6-dinitrotoluene to 43ng/mL for 4-amino-2,6-dinitrotoluene. Major impurities in TNT were 2,4-dinitrotoluene and 2,3,4-trinitrotoluene. Impurity profiles based on seven compounds showed to be useful to TNT samples from different sources. Statistical analysis of these impurity profiles using likelihood ratios demonstrated the potential to investigate whether two questioned TNT samples encountered in forensic casework are from the same source.

  2. Impurity Studies of Cd(0.8)Zn(0.2)Te Crystals Using Photoluminescence and Glow Discharge Mass Spectroscopy

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Lehoczky, Sandor L.; Scripa, Rosalie N.

    2005-01-01

    Cd(1-x)Zn(x)Te semiconductor crystal is a highly promising material for room temperature x- and gamma-ray detector applications because of its high resistivity, long carrier lifetime, and relatively high hole and electron mobilities. This paper reports the investigation of the impurities in several Cd(1-x)Zn(x)Te (x = 0.20) crystals grown using the vertical Bridgman method under a Cd overpressure. The impurity concentrations were measured using glow discharge mass spectroscopy (GDMS). The energy states of the impurities were studied using photoluminescence (PL) spectroscopy at liquid helium temperature. The PL spectra showed a series of sharp high energy lines which are associated with free excitons and excitons bound to impurities as donors and acceptors in the crystals. The impurities also contributed to donor-acceptor pair recombination. The correlation between the GDMS and PL results will be reported.

  3. Electronic structure and local magnetism of 3d-5d impurity substituted CeFe2

    NASA Astrophysics Data System (ADS)

    Das, Rakesh; Das, G. P.; Srivastava, S. K.

    2016-04-01

    We present here a systematic first-principles study of electronic structure and local magnetic properties of Ce[Fe0.75M0.25]2 compounds, where M is a 3d, 4d or 5d transition or post-transition element, using the generalized gradient approximation of the density functional theory. The d-f band hybridizations existing in CeFe2 get modified by the impurity M in an orderly manner across a period for each impurity series: the hybridization is strongest for the Mn group impurity in the period and gets diminished on either side of it. The weakening of the d-f hybridization strength is also associated with a relative localization of the Ce 4f states with respect to the delocalized 4f states in CeFe2. The above effects are most prominent for 3d impurity series, while for 4d and 5d impurities, the hybridizations and relocalizations are relatively weak due primarily to the relatively extended nature of 4d and 5d wavefunctions. The Ce local moment is found to decrease from the CeFe2 value in proportion to the strength of relocalization, thus following almost the same orderly trend as obeyed by the d-f hybridization. Further, depending on the way the spin-up and spin-down densities of states of an impurity shift relative to the Fermi energy, the impurity local moments are highest for Mn or Fe group, reduce on either side, become zero for Ni to Ga, and are small but negative for V and Ti. The Ce hyperfine field is found to follow the M local moment in a linear fashion, and vice-versa.

  4. Marital Processes around Depression: A Gendered and Relational Perspective

    PubMed Central

    Thomeer, Mieke Beth; Umberson, Debra; Pudrovska, Tetyanna

    2015-01-01

    Despite extensive evidence of the importance of marriage and marital processes for mental health, little is known about the interpersonal processes around depression within marriage and the extent to which these processes are gendered. We use a mixed methods approach to explore the importance of gender in shaping processes around depression within marriage; we approach this in two ways. First, using quantitative longitudinal analysis of 2,601 couples from the Health and Retirement Study (HRS), we address whether depressive symptoms in one spouse shape the other spouse's depressive symptoms and whether men or women are more influential in this process. We find that a wife's depressive symptoms influence her husband's future depressive symptoms but a husband's depressive symptoms do not influence his wife's future symptoms. Second, we conduct a qualitative analysis of in-depth interviews with 29 couples wherein one or both spouses experienced depression to provide additional insight into how gender impacts depression and reactions to depression within marriage. Our study points to the importance of cultural scripts of masculinity and femininity in shaping depression and emotional processes within marriage and highlights the importance of applying a gendered couple-level approach to better understand the mental health effects of marital processes. PMID:25914855

  5. Isotopic and impurity element probes of mesoscale chemical dynamics at mineral fluid interfaces

    NASA Astrophysics Data System (ADS)

    DePaolo, D. J.

    2012-12-01

    Mesoscale interactions control important Earth processes including the growth of minerals from aqueous solutions and silicate liquids, the diffusion of ions in solids and silicate liquids, and the solid-state deformation and recrystallization that constitutes metamorphism. Most of these processes are typically understood from the classical side in terms of macroscopic physical and thermodynamic properties and classical kinetics, and from the molecular side in terms of single molecule or nearest-neighbor interactions. However, in many cases the controlling processes occur at intermediate scales of both length and time, and involve complex interactions among multiple chemical species. A major limitation has been in characterizing and modeling the dynamic processes that lead to the macroscopic properties and behavior. Advanced microscopy techniques allow phase changes, for example, to be monitored at high resolution, and this capability continues to improve. However, other important information about the phase changes, such as the molecular exchange fluxes between phases and the detailed mechanisms of reaction, are not revealed by microscopy. High-resolution isotopic characterization now allows the molecular exchange fluxes to be quantified, and models suggest that the incorporation of impurity elements is directly tied to these fluxes. One of the main advances is that precise isotopic measurements have recently been extended to include major stoichiometric cations such as Ca, Mg, Fe, and K, as well as key impurity elements such as U, Cd, Mo, and Sr. Isotopic analysis at the nano- to microscale would further clarify the detailed dynamics of mineral chemistry controls but are not yet possible except in a few instances. Impurity element concentrations are more easily measured at these small scales, and they are a key bridge between isotopic measurements and microscopy.Other limitations to advancing our knowledge of the chemical and isotopic effects associated with

  6. A comprehensive strategy in the development of a cyclodextrin-modified microemulsion electrokinetic chromatographic method for the assay of diclofenac and its impurities: Mixture-process variable experiments and quality by design.

    PubMed

    Orlandini, S; Pasquini, B; Caprini, C; Del Bubba, M; Squarcialupi, L; Colotta, V; Furlanetto, S

    2016-09-30

    A comprehensive strategy involving the use of mixture-process variable (MPV) approach and Quality by Design principles has been applied in the development of a capillary electrophoresis method for the simultaneous determination of the anti-inflammatory drug diclofenac and its five related substances. The selected operative mode consisted in microemulsion electrokinetic chromatography with the addition of methyl-β-cyclodextrin. The critical process parameters included both the mixture components (MCs) of the microemulsion and the process variables (PVs). The MPV approach allowed the simultaneous investigation of the effects of MCs and PVs on the critical resolution between diclofenac and its 2-deschloro-2-bromo analogue and on analysis time. MPV experiments were used both in the screening phase and in the Response Surface Methodology, making it possible to draw MCs and PVs contour plots and to find important interactions between MCs and PVs. Robustness testing was carried out by MPV experiments and validation was performed following International Conference on Harmonisation guidelines. The method was applied to a real sample of diclofenac gastro-resistant tablets. PMID:27623066

  7. Time-Driven Effects on Processing Relative Clauses

    ERIC Educational Resources Information Center

    Schremm, Andrea; Horne, Merle; Roll, Mikael

    2016-01-01

    The present response time study investigated how a hypothesized time-based working memory constraint of 2-3 s affects the resolution of grammatical and semantic dependencies. Congruent and incongruent object relative (OR) and subject relative sentences were read at different presentation rates so that the distance between dependent words was…

  8. The Relational-Cultural Model: A Framework for Group Process

    ERIC Educational Resources Information Center

    Comstock, Dana L.; Duffey, Thelma; St. George, Holly

    2002-01-01

    The relational-cultural model of psychotherapy has been evolving for the past 20 years. Within this model, difficult group dynamics are conceptualized as the playing out of the central relational paradox. This paradox recognizes that an individual may yearn for connection but, out of a sense of fear, simultaneously employ strategies that restrict…

  9. Experience and Sentence Processing: Statistical Learning and Relative Clause Comprehension

    ERIC Educational Resources Information Center

    Wells, Justine B.; Christiansen, Morten H.; Race, David S.; Acheson, Daniel J.; MacDonald, Maryellen C.

    2009-01-01

    Many explanations of the difficulties associated with interpreting object relative clauses appeal to the demands that object relatives make on working memory. MacDonald and Christiansen [MacDonald, M. C., & Christiansen, M. H. (2002). "Reassessing working memory: Comment on Just and Carpenter (1992) and Waters and Caplan (1996)." "Psychological…

  10. Relativity Based on Physical Processes Rather Than Space-Time

    NASA Astrophysics Data System (ADS)

    Giese, Albrecht

    2013-09-01

    Physicists' understanding of relativity and the way it is handled is at present dominated by the interpretation of Albert Einstein, who related relativity to specific properties of space and time. The principal alternative to Einstein's interpretation is based on a concept proposed by Hendrik A. Lorentz, which uses knowledge of classical physics to explain relativistic phenomena. In this paper, we will show that on the one hand the Lorentz-based interpretation provides a simpler mathematical way of arriving at the known results for both Special and General Relativity. On the other hand, it is able to solve problems which have remained open to this day. Furthermore, a particle model will be presented, based on Lorentzian relativity, which explains the origin of mass without the use of the Higgs mechanism, based on the finiteness of the speed of light, and which provides the classical results for particle properties that are currently only accessible through quantum mechanics.

  11. Some Examples of the Relations Between Processing and Damage Tolerance

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.

    2012-01-01

    Most structures made of laminated polymer matrix composites (PMCs) must be designed to some damage tolerance requirement that includes foreign object impact damage. Thus from the beginning of a part s life, impact damage is assumed to exist in the material and the part is designed to carry the required load with the prescribed impact damage present. By doing this, some processing defects may automatically be accounted for in the reduced design allowable due to these impacts. This paper will present examples of how a given level of impact damage and certain processing defects affect the compression strength of a laminate that contains both. Knowledge of the impact damage tolerance requirements, before processing begins, can broaden material options and processing techniques since the structure is not being designed to pristine properties.

  12. Electrophysiological CNS-processes related to associative learning in humans.

    PubMed

    Christoffersen, Gert R J; Schachtman, Todd R

    2016-01-01

    The neurophysiology of human associative memory has been studied with electroencephalographic techniques since the 1930s. This research has revealed that different types of electrophysiological processes in the human brain can be modified by conditioning: sensory evoked potentials, sensory induced gamma-band activity, periods of frequency-specific waves (alpha and beta waves, the sensorimotor rhythm and the mu-rhythm) and slow cortical potentials. Conditioning of these processes has been studied in experiments that either use operant conditioning or repeated contingent pairings of conditioned and unconditioned stimuli (classical conditioning). In operant conditioning, the appearance of a specific brain process is paired with an external stimulus (neurofeedback) and the feedback enables subjects to obtain varying degrees of control of the CNS-process. Such acquired self-regulation of brain activity has found practical uses for instance in the amelioration of epileptic seizures, Autism Spectrum Disorders (ASD) and Attention Deficit Hyperactivity Disorder (ADHD). It has also provided communicative means of assistance for tetraplegic patients through the use of brain computer interfaces. Both extra and intracortically recorded signals have been coupled with contingent external feedback. It is the aim for this review to summarize essential results on all types of electromagnetic brain processes that have been modified by classical or operant conditioning. The results are organized according to type of conditioned EEG-process, type of conditioning, and sensory modalities of the conditioning stimuli.

  13. Influence of Bi-related impurity states on the bandgap and spin-orbit splitting energy of dilute III-V-Bi alloys: InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix

    NASA Astrophysics Data System (ADS)

    Samajdar, D. P.; Dhar, S.

    2016-01-01

    Valence Band Anticrossing (VBAC) Model is used to calculate the changes in band structure of Bi containing alloys such as InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix due to the incorporation of dilute concentrations of bismuth. The coupling parameter CBi which gives the magnitude of interaction of Bi impurity states with the LH, HH and SO sub bands in VBAC depends on the increase in the HH/LH related energy level EHH/LH+, location of the Bi related impurity level EBi and valence band offset ΔEVBM between the endpoint compounds in the corresponding III-V-Bi. The reduction in band gap as well as the enhancement of the spin-orbit splitting energy is well explained using this model and the calculated results are compared with the results of Virtual Crystal Approximation (VCA) and Density Functional Theory (DFT) calculations, as well as with the available experimental data and are found to have good agreement. The incorporation of Bi mainly perturbs the valence band due to the interaction of the Bi impurity states with the HH, LH and SO bands. The lowering of the conduction band minimum (CBM) due to VCA is added with the upward movement of the HH/LH bands to get the total reduction in band gap for the bismides. The valence band shifts of 31.9, 32.5, 20.8 and 12.4 meV/at%Bi for InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix respectively constitute 65, 76, 59 and 31% of the total band gap reduction and the rest is the contribution of the conduction band shift. The spin-orbit splitting energy also shows significant increase with the maximum change in InPBi and the minimum in InSbBi. The same is true for Ga containing bismides if we make a comparison with the available values for GaAsBi and GaPBi with that of GaSbBi. It has also been observed that the increase in splitting energy is greater in case of the bismides such as InAsBi, InPBi and GaAsBi than the bismides such as InSbBi and GaSbBi with the parent substrates having higher values of splitting energy. This may

  14. Rapid emotional processing in relation to trauma-related symptoms as revealed by magnetic source imaging

    PubMed Central

    2014-01-01

    Background Traumatic stress leads to functional reorganization in the brain and may trigger an alarm response. However, when the traumatic event produces severe helplessness, the predominant peri-traumatic response may instead be marked by a dissociative shutdown reaction. The neural correlates of this dissociative shutdown were investigated by presenting rapidly presented affective pictures to female participants with posttraumatic stress disorder (PTSD), and comparing responses to a Non-PTSD control group. Methods Event-related-magnetic-fields were recorded during rapid visual serial presentation of emotionally arousing stimuli (unpleasant or pleasant), which alternated with pictures with low affective content (neutral). Neural sources, based on the L2-surface-minimum-norm, correlated with the severity of the symptom clusters: PTSD, depression and shutdown dissociation. Results For the early cortical response (60 to 110 ms), dissociation and PTSD symptom severity show similar spatial distributions of correlates for unpleasant stimuli. Cortical networks that could be involved in the relationships seem to be widespread. Conclusion We conclude that shutdown dissociation, PTSD and depression all have distinct effects on early processing of emotional stimuli. PMID:24997778

  15. Spectral properties of superconductors with ferromagnetically ordered magnetic impurities

    NASA Astrophysics Data System (ADS)

    Persson, Daniel; Shevtsov, Oleksii; Löfwander, Tomas; Fogelström, Mikael

    2015-12-01

    We present a comprehensive theoretical study of thermodynamic properties of superconductors with a dilute concentration of magnetic impurities, with focus on how the properties of the superconducting host change if the magnetic moments of the impurities order ferromagnetically. Scattering off the magnetic impurities leads to the formation of a band of Yu-Shiba-Rusinov states within the superconducting energy gap that drastically influences superconductivity. In the magnetically ordered system, the magnetization displays a sudden drop as a function of the impurity density or magnetic moment amplitude. The drop occurs as the spin-polarized impurity band crosses the Fermi level and is associated with a quantum phase transition first put forward by Sakurai for the single impurity case. Taking into account that the background magnetic field created by the ordered impurity moments enters as a Zeeman shift, we find that the superconducting phase transition changes from second order to first order for high enough impurity concentrations.

  16. 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.

  17. Controlling the Didactic Relation: A Case in Process Engineering Education

    ERIC Educational Resources Information Center

    Jaako, Juha

    2014-01-01

    A case study was conducted during 1994-2013 on several groups of process engineering students to see what was needed to transform a single course from a teacher-centred to a student-centred learning environment (SCLE). Development work was done incrementally, using Herbart's didactic triangle as a theoretical framework. The effects of the…

  18. [Attitudes of nursing staff related to the nursing process].

    PubMed

    Guedes, Erika de Souza; Turrini, Ruth Natália Teresa; de Sousa, Regina Márcia Cardoso; Baltar, Valéria Troncoso; da Cruz, Diná de Almeida Lopes Monteiro

    2012-10-01

    The aims of the study were to describe nurses' positions on nursing process and their perception of power; and to analyse associations between positions on nursing process, power perception and selected variables. One thousand six hundred and five nurses (86.9% female, mean age=44.12 years, SD=9.55) participated in the study. Mean score on the Positions on Nursing Process (PNP) tool was 112.37 (SD=22.28); and on the Power as Knowing Participation in Change Tool - Brazilian Version (PKPCT) was 281.12 (SD=38.72). Baccalaureate nurses had statistically higher scores on PNP and PKPCT than auxiliary nurses. There was positive and moderate correlation between PNP and PKPCT scores. Auxiliary nurses' scores on PNP were associated with sex and post-graduation; auxiliary nurses' scores on PKPCT were associated with sex. For baccalaureate nurses there was association between PKPCT and administrative position. More studies should be developed in order to identify variables potentially associated with the use of nursing process in clinical practice. PMID:23250269

  19. Drugs, Recipes, Babies, Bathwater, and Psychotherapy Process-Outcome Relations.

    ERIC Educational Resources Information Center

    Stiles, William B.

    1994-01-01

    Responds to critiques of Stiles and Shapiro's (1994) discussion of process-outcome correlation problem by Silberschatz (1994) and Sechrest (1994). Contends that, contrary to Silberschatz's and Sechrest's multivariate suggestions, problem is not in measures or analyses but in interpretation of results, particularly in failure to incorporate fully…

  20. Emerging Adulthood: Age-Related Tasks and Underlying Self Processes

    ERIC Educational Resources Information Center

    Shulman, Shmuel; Feldman, Benni; Blatt, Sidney; Cohen, Omri; Mahler, Amalya

    2005-01-01

    Seventy-two Israeli emerging adults were interviewed for descriptions of themselves and accounts of their personal, social, and professional dreams, current life status, romantic relationships, and relationships with their parents. Interviews were transcribed and rated on scales assessing self-processes, attainment of professional and romantic…

  1. Relating Right Brain Studies to the Design Process.

    ERIC Educational Resources Information Center

    Hofland, John

    Intended for teachers of theatrical design who need to describe a design process for their students, this paper begins by giving a brief overview of recent research that has described the different functions of the right and left cerebral hemispheres. It then notes that although the left hemisphere tends to dominate the right hemisphere, it is the…

  2. Considerations in the Educational Process Relative to Native Americans

    ERIC Educational Resources Information Center

    Calsoyas, Kyril

    2005-01-01

    Relationships between the educational process, society, and the individual are explored through an examination of the nature of truth and the sources of knowledge for each of these elements. A utilitarian model of education is explored with regard to the tensions between individual perception and self expression and the needs and constraints of…

  3. Evaluation of Impurity Extremes in a Plutonium-loaded Borosilicate Glass

    SciTech Connect

    Fox, K.M.; Crawford, C.L.; Marra, J.C.; Bibler, N.E.; Hoffman, E.N.; Edwards, T.B.

    2008-07-01

    A vitrification technology utilizing a lanthanide borosilicate (LaBS) glass appears to be a viable option for the disposition of excess weapons-usable plutonium that is not suitable for processing into mixed oxide (MOX) fuel. A significant effort to develop a glass formulation and vitrification process to immobilize plutonium was completed in the mid-1990's. The LaBS glass formulation was found to be capable of immobilizing in excess of 10 wt % Pu and to be tolerant of a range of impurities. To confirm the results of previous testing with surrogate Pu feeds containing impurities, four glass compositions were selected for fabrication with actual plutonium oxide and impurities. The four compositions represented extremes in impurity type and concentration. The homogeneity and durability of these four compositions were measured. The homogeneity of the glasses was evaluated using x-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). The XRD results indicated that the glasses were amorphous with no evidence of crystalline species in the glass. The SEM/EDS analyses did show the presence of some undissolved PuO{sub 2} material. The EDS spectra indicated that some of the PuO{sub 2} crystals also contained hafnium oxide. The SEM/EDS analyses showed that there were no heterogeneities in the glass due to the feed impurities. The durability of the glasses was measured using the Product Consistency Test (PCT). The PCT results indicated that the durability of Pu impurity glasses was comparable with Pu glasses without impurities and significantly more durable than the Environmental Assessment (EA) glass used as the benchmark for repository disposition of high-level waste (HLW) glasses. (authors)

  4. EVALUATION OF IMPURITY EXTREMES IN A PLUTONIUM-LOADED BOROSILICATE GLASS

    SciTech Connect

    Marra, J; Kevin Fox, K; Charles Crawford, C; Ned Bibler, N; Elizabeth Hoffman, E; Tommy Edwards, T

    2007-11-12

    A vitrification technology utilizing a lanthanide borosilicate (LaBS) glass appears to be a viable option for the disposition of excess weapons-useable plutonium that is not suitable for processing into mixed oxide (MOX) fuel. A significant effort to develop a glass formulation and vitrification process to immobilize plutonium was completed in the mid-1990s. The LaBS glass formulation was found to be capable of immobilizing in excess of 10 wt % Pu and to be tolerant of a range of impurities. To confirm the results of previous testing with surrogate Pu feeds containing impurities, four glass compositions were selected for fabrication with actual plutonium oxide and impurities. The four compositions represented extremes in impurity type and concentration. The homogeneity and durability of these four compositions were measured. The homogeneity of the glasses was evaluated using x-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). The XRD results indicated that the glasses were amorphous with no evidence of crystalline species in the glass. The SEM/EDS analyses did show the presence of some undissolved PuO{sub 2} material. The EDS spectra indicated that some of the PuO{sub 2} crystals also contained hafnium oxide. The SEM/EDS analyses showed that there were no heterogeneities in the glass due to the feed impurities. The durability of the glasses was measured using the Product Consistency Test (PCT). The PCT results indicated that the durability of Pu impurity glasses was comparable with Pu glasses without impurities and significantly more durable than the Environmental Assessment (EA) glass used as the benchmark for repository disposition of high-level waste (HLW) glasses.

  5. 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

  6. Ultrafast many-body interferometry of impurities coupled to a Fermi sea

    NASA Astrophysics Data System (ADS)

    Cetina, Marko; Jag, Michael; Lous, Rianne S.; Fritsche, Isabella; Walraven, Jook T. M.; Grimm, Rudolf; Levinsen, Jesper; Parish, Meera M.; Schmidt, Richard; Knap, Michael; Demler, Eugene

    2016-10-01

    The fastest possible collective response of a quantum many-body system is related to its excitations at the highest possible energy. In condensed matter systems, the time scale for such “ultrafast” processes is typically set by the Fermi energy. Taking advantage of fast and precise control of interactions between ultracold atoms, we observed nonequilibrium dynamics of impurities coupled to an atomic Fermi sea. Our interferometric measurements track the nonperturbative quantum evolution of a fermionic many-body system, revealing in real time the formation dynamics of quasi-particles and the quantum interference between attractive and repulsive states throughout the full depth of the Fermi sea. Ultrafast time-domain methods applied to strongly interacting quantum gases enable the study of the dynamics of quantum matter under extreme nonequilibrium conditions.

  7. Effect of impurity doping concentration on solar cell output

    NASA Technical Reports Server (NTRS)

    Iles, P. A.; Soclof, S. I.

    1975-01-01

    Experimental measurements were made of solar cell and related photovoltaic parameters for silicon with high concentrations of dopant impurities. The cell output peaked for doping levels around 10 to the 17th power per cu cm. Independent measurements of diffusion length and open circuit voltage at high doping levels showed severe reductions at concentrations above 10 to the 18th power per cu cm. Theoretical reasons are given to explain these reductions. Indication is given of the problems requiring solution before increased cell output can be achieved at high doping levels.

  8. 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.

  9. Home Visiting Processes: Relations with Family Characteristics and Outcomes

    ERIC Educational Resources Information Center

    Peterson, Carla A.; Roggman, Lori A.; Green, Beth; Chazan-Cohen, Rachel; Korfmacher, Jon; McKelvey, Lorraine; Zhang, Dong; Atwater, Jane B.

    2013-01-01

    Variations in dosage, content, and family engagement with Early Head Start (EHS) home visiting services were examined for families participating in the EHS Research and Evaluation Project. Families were grouped by characteristics of maternal age, maternal ethnicity, and level of family risk. All home visiting variables were related differentially…

  10. Managing the Industrial Labor Relations Process in Higher Education.

    ERIC Educational Resources Information Center

    Julius, Daniel J., Ed.

    This book contains 25 essays on the subject of industrial relations divided into the following parts: Essays and their authors are as follows: "The Context of Collective Bargaining in American Colleges and Universities" (Kenneth P. Mortimer); "Transformation of the U.S. Collective Bargaining System: The Impact on Higher Education" (James P.…

  11. Linking Production and Comprehension Processes: The Case of Relative Clauses

    ERIC Educational Resources Information Center

    Gennari, Silvia P.; MacDonald, Maryellen C.

    2009-01-01

    Six studies investigated the relationship between production and comprehension by examining how relative clause production mechanisms influence the probabilistic information used by comprehenders to understand these structures. Two production experiments show that accessibility-based mechanisms that are influenced by noun animacy and verb type…

  12. Oxidation processes in magneto-optic and related materials

    NASA Technical Reports Server (NTRS)

    Lee, Paul A.; Armstrong, Neal R.; Danzinger, James L.; England, Craig D.

    1992-01-01

    The surface oxidation processes of thin films of magneto-optic materials, such as the rare-earth transition metal alloys have been studied, starting in ultrahigh vacuum environments, using surface analysis techniques, as a way of modeling the oxidation processes which occur at the base of a defect in an overcoated material, at the instant of exposure to ambient environments. Materials examined have included FeTbCo alloys, as well as those same materials with low percentages of added elements, such a Ta, and their reactivities to both O2 and H2O compared with materials such as thin Fe films coated with ultrathin adlayers of Ti. The surface oxidation pathways for these materials is reviewed, and XPS data presented which indicates the type of oxides formed, and a critical region of Ta concentration which provides optimum protection.

  13. Integrative techniques related to positive processes in psychotherapy.

    PubMed

    Cromer, Thomas D

    2013-09-01

    This review compiles and evaluates a number of therapist interventions that have been found to significantly contribute to positive psychotherapy processes (i.e., increased alliance, patient engagement/satisfaction, and symptomatic improvement). Four forms of intervention are presented: Affect-focused, Supportive, Exploratory, and Patient-Therapist Interaction. The intention of this review is to link specific interventions to applied practice so that integrative clinicians can potentially use these techniques to improve their clinical work. To this end, there is the inclusion of theory and empirical studies from a range of orientations including Emotionally Focused, Psychodynamic, Client-Centered, Cognitive-Behavioral, Interpersonal, Eclectic, and Motivational Interviewing. Each of the four sections will include the theoretical basis and proposed mechanism of change for the intervention, research that supports its positive impact on psychotherapy processes, and conclude with examples demonstrating its use in actual practice. Clinical implications and considerations regarding the use of these interventions will also be presented.

  14. Infant Auditory Processing and Event-related Brain Oscillations

    PubMed Central

    Musacchia, Gabriella; Ortiz-Mantilla, Silvia; Realpe-Bonilla, Teresa; Roesler, Cynthia P.; Benasich, April A.

    2015-01-01

    Rapid auditory processing and acoustic change detection abilities play a critical role in allowing human infants to efficiently process the fine spectral and temporal changes that are characteristic of human language. These abilities lay the foundation for effective language acquisition; allowing infants to hone in on the sounds of their native language. Invasive procedures in animals and scalp-recorded potentials from human adults suggest that simultaneous, rhythmic activity (oscillations) between and within brain regions are fundamental to sensory development; determining the resolution with which incoming stimuli are parsed. At this time, little is known about oscillatory dynamics in human infant development. However, animal neurophysiology and adult EEG data provide the basis for a strong hypothesis that rapid auditory processing in infants is mediated by oscillatory synchrony in discrete frequency bands. In order to investigate this, 128-channel, high-density EEG responses of 4-month old infants to frequency change in tone pairs, presented in two rate conditions (Rapid: 70 msec ISI and Control: 300 msec ISI) were examined. To determine the frequency band and magnitude of activity, auditory evoked response averages were first co-registered with age-appropriate brain templates. Next, the principal components of the response were identified and localized using a two-dipole model of brain activity. Single-trial analysis of oscillatory power showed a robust index of frequency change processing in bursts of Theta band (3 - 8 Hz) activity in both right and left auditory cortices, with left activation more prominent in the Rapid condition. These methods have produced data that are not only some of the first reported evoked oscillations analyses in infants, but are also, importantly, the product of a well-established method of recording and analyzing clean, meticulously collected, infant EEG and ERPs. In this article, we describe our method for infant EEG net

  15. Relative efficiency of Gaussian stochastic process sampling procedures

    NASA Astrophysics Data System (ADS)

    Cameron, Chris

    2003-12-01

    Various methods for sampling stationary, Gaussian stochastic processes are investigated and compared with an emphasis on applications to processes with power law energy spectra. Several approaches are considered, including a Riemann summation using left endpoints, the use of random wave numbers to sample a the spectrum in proportion to the energy it contains, and a combination of the two. The Fourier-wavelet method of Elliott et al. is investigated and compared with other methods, all of which are evaluated in terms of their ability to sample the stochastic process over a large number of decades for a given computational cost. The Fourier-wavelet method has accuracy which increases linearly with the computational complexity, while the accuracy of the other methods grows logarithmically. For the Kolmogorov spectrum, a hybrid quadrature method is as efficient as the Fourier-wavelet method, if no more than eight decades of accuracy are required. The effectiveness of this hybrid method wanes when one samples fields whose energy spectrum decays more rapidly near the origin. The Fourier-wavelet method has roughly the same behavior independently of the exponent of the power law. The Fourier-wavelet method returns samples which are Gaussian over the range of values where the structure function is well approximated. By contrast, (multi-point) Gaussianity may be lost at the smaller length scales when one uses methods with random wave numbers.

  16. Metal-based impurities in graphenes: application for electroanalysis.

    PubMed

    Chee, Sze Yin; Pumera, Martin

    2012-05-01

    We show here that metallic impurities presented in graphenes prepared from graphite can be usefully employed for electroanalysis. We demonstrate that cumene hydroperoxide electrochemical reduction on graphene containing iron-based impurities provides significantly larger voltammetric currents than the same experiment using iron oxide nanoparticles. This opens doors for turning metallic impurities into potentially useful components of graphene based electrochemical systems.

  17. Monte Carlo method for magnetic impurities in metals

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  18. Processing of Pheromone Information in Related Species of Heliothine Moths

    PubMed Central

    Berg, Bente G.; Zhao, Xin-Cheng; Wang, Guirong

    2014-01-01

    In heliothine moths, the male-specific olfactory system is activated by a few odor molecules, each of which is associated with an easily identifiable glomerulus in the primary olfactory center of the brain. This arrangement is linked to two well-defined behavioral responses, one ensuring attraction and mating behavior by carrying information about pheromones released by conspecific females and the other inhibition of attraction via signal information emitted from heterospecifics. The chance of comparing the characteristic properties of pheromone receptor proteins, male-specific sensory neurons and macroglomerular complex (MGC)-units in closely-related species is especially intriguing. Here, we review studies on the male-specific olfactory system of heliothine moths with particular emphasis on five closely related species, i.e., Heliothis virescens, Heliothis subflexa, Helicoverpa zea, Helicoverpa assulta and Helicoverpa armigera. PMID:26462937

  19. Empirical relations for cavitation and liquid impingement erosion processes

    NASA Technical Reports Server (NTRS)

    Rao, P. V.; Buckley, D. H.

    1984-01-01

    A unified power-law relationship between average erosion rate and cumulative erosion is presented. Extensive data analyses from venturi, magnetostriction (stationary and oscillating specimens), liquid drop, and jet impact devices appear to conform to this relation. A normalization technique using cavitation and liquid impingement erosion data is also presented to facilitate prediction. Attempts are made to understand the relationship between the coefficients in the power-law relationships and the material properties.

  20. Spray forming process for producing molds, dies and related tooling

    DOEpatents

    McHugh, Kevin M.; Key, James F.

    1998-01-01

    A method for spray forming manufacturing of near-net-shape molds, dies and related toolings, wherein liquid material such as molten metal, metallic alloys, or polymers are atomized into fine droplets by a high temperature, high velocity gas and deposited onto a pattern. Quenching of the atomized droplets provides a heat sink, thereby allowing undercooled and partially solidified droplets to be formed in-flight. Composites can be formed by combining the atomized droplets with solid particles such as whiskers or fibers.

  1. Self-pumping impurity control

    DOEpatents

    Brooks, Jeffrey N.; Mattas, Richard F.

    1991-01-01

    Apparatus for removing the helium ash from a fusion reactor having a D-T plasma comprises a helium trapping site within the reactor plasma confinement device, said trapping site being formed of a trapping material having negligible helium solubility and relatively high hydrogen solubility; and means for depositing said trapping material on said site at a rate sufficient to prevent saturation of helium trapping.

  2. Batch Preheat for glass and related furnace processing operations

    SciTech Connect

    Energy & Environmental Resources, Inc

    2002-08-12

    The objectives that our development work addressed are: (1) Establish through lab tests a salt eutectic with a melting point of about 250 F and a working range of 250 to 1800 F. (2) Establish the most economical material of construction for the screened salt eutectics identified in the first objective. (3) Establish the material of construction for the salt heater liner. Objectives 2 and 3 were determined through corrosion tests using selected metallurgical samples. Successful completion of the above-stated goals will be incorporated in a heat recovery design that can be used in high temperature processes and furnaces, typical of which is the glass melting process. The process design incorporates the following unit operations: a vertical batch heater (whereby the batch flows down through tubes in a shell and tube exchanger; a molten salt eutectic is circulated on the shell side); a molten salt heater utilizing furnace flue gas in a radiation type heater (molten salt is circulated in the annular space between the inner and outer shells of the vertical heater, and flue gas passes from the furnace exhaust through the inner shell of the heater); a cantilever type molten salt circulating pump; and a jacketed mixer/conveyor to drive off moisture from the batch prior to feeding the batch to the vertical batch heater. Historically, radiation heaters, when applied to glass or fiberglass furnace recuperation, have experienced failures due to uneven heat flux rates, which increases internal stresses and spot overheating conditions. Low heat transfer coefficients result in requirements for large heat transfer surface areas in gas to gas or gas to air exchangers. Fouling is another factor that results in lower unit availability and reduced performance. These factors are accommodated in this process by the incorporation of several design features. The salt heater will be a vertical double wall radiation design, similar to radiation air heaters used in high temperature heat

  3. Scattering-induced quantum correlation in electronic waveguides with static magnetic impurities

    NASA Astrophysics Data System (ADS)

    Ghanbari-Adivi, E.; Soltani, M.; Alami, Z.; Sheikhali, M.

    2016-07-01

    Entanglement generation due to low-energy scattering of the transporting electrons in an electronic waveguide by a quantum dot magnetic impurity is theoretically investigated. The transverse confining potential of the waveguide is considered as a two-dimensional harmonic potential, and the interaction of the electron with the impurity is described by a zero-range pseudopotential modulated by an Ising or a Heisenberg spin interaction. Our calculation shows that the scattering process leads to creation of a considerable amount of entanglement in the state of the reflected and transmitted electrons. The situation is extended to the scattering of the electrons by two well-separated magnetic impurities localized on the nanowire axis. It is shown that the scattering process causes the magnetic impurities embedded in the nanowire to share their quantum information; subsequently, they can be entangled by spin interaction with the injected electron. The created entanglement between the impurities is calculated and discussed. It is shown that the exact three-dimensional problem can be approximated as a one-dimensional problem under certain circumstances. The approximate results are compared to exact calculations and discussed.

  4. Scattering-induced quantum correlation in electronic waveguides with static magnetic impurities

    NASA Astrophysics Data System (ADS)

    Ghanbari-Adivi, E.; Soltani, M.; Alami, Z.; Sheikhali, M.

    2016-10-01

    Entanglement generation due to low-energy scattering of the transporting electrons in an electronic waveguide by a quantum dot magnetic impurity is theoretically investigated. The transverse confining potential of the waveguide is considered as a two-dimensional harmonic potential, and the interaction of the electron with the impurity is described by a zero-range pseudopotential modulated by an Ising or a Heisenberg spin interaction. Our calculation shows that the scattering process leads to creation of a considerable amount of entanglement in the state of the reflected and transmitted electrons. The situation is extended to the scattering of the electrons by two well-separated magnetic impurities localized on the nanowire axis. It is shown that the scattering process causes the magnetic impurities embedded in the nanowire to share their quantum information; subsequently, they can be entangled by spin interaction with the injected electron. The created entanglement between the impurities is calculated and discussed. It is shown that the exact three-dimensional problem can be approximated as a one-dimensional problem under certain circumstances. The approximate results are compared to exact calculations and discussed.

  5. The Consultancy Activity on In Silico Models for Genotoxic Prediction of Pharmaceutical Impurities.

    PubMed

    Pavan, Manuela; Kovarich, Simona; Bassan, Arianna; Broccardo, Lorenza; Yang, Chihae; Fioravanzo, Elena

    2016-01-01

    The toxicological assessment of DNA-reactive/mutagenic or clastogenic impurities plays an important role in the regulatory process for pharmaceuticals; in this context, in silico structure-based approaches are applied as primary tools for the evaluation of the mutagenic potential of the drug impurities. The general recommendations regarding such use of in silico methods are provided in the recent ICH M7 guideline stating that computational (in silico) toxicology assessment should be performed using two (Q)SAR prediction methodologies complementing each other: a statistical-based method and an expert rule-based method.Based on our consultant experience, we describe here a framework for in silico assessment of mutagenic potential of drug impurities. Two main applications of in silico methods are presented: (1) support and optimization of drug synthesis processes by providing early indication of potential genotoxic impurities and (2) regulatory evaluation of genotoxic potential of impurities in compliance with the ICH M7 guideline. Some critical case studies are also discussed.

  6. Impurity production and plasma performance in ASDEX discharges with ohmic and auxiliary heating

    NASA Astrophysics Data System (ADS)

    Fussmann, G.; ASDEX Team; NI Team; Icrh Team; Hofmann, J.; Janeschitz, G.; Lenoci, M.; Mast, F.; McCormick, K.; Murmann, H.; Poschenrieder, W.; Roth, J.; Setzensack, C.; Staudenmaier, G.; Steuer, K.-H.; Taglauer, E.; Verbeek, H.; Wagner, F.; Becker, G.; Bosch, H. S.; Brocken, H.; Eberhagen, A.; Gehre, O.; Gernhardt, J.; Gierke, G. V.; Clock, E.; Gruber, O.; Haas, G.; Izvozchikov, A.; Karger, F.; Kaufmann, M.; Keilhacker, M.; Klüber, O.; Kornherr, M.; Lackner, K.; Lisitano, G.; Mayer, H. M.; Meisel, D.; Mertens, V.; Müller, E. R.; Neuhauser, J.; Niedermeyer, H.; Noterdaeme, J.-M.; Pietrzyk, Z. A.; Rapp, H.; Riedler, H.; Röhr, H.; Ryter, F.; Schneider, F.; Siller, G.; Smeulders, P.; Söldner, F. X.; Speth, E.; Steinmetz, K.; Tsois, N.; Ugniewski, S.; Vollmer, O.; Wesner, F.; Zasche, D.

    1987-02-01

    A review is given on investigations in the ASDEX Tokamak on impurities in ohmically, NI and ICRH heated plasmas. For ohmic discharges in H 2 and D 2 it is found that iron release from the wall can be explained by sputtering due to neutral charge exchange (CX) atoms. In the case of He, however, significant contributions caused by ion sputtering are inferred. Comparing discharges with C limiters in He and D 2 suggests that in the case of hydrogen chemical processes are involved in C sputtering. By means of wall carbonization the concentrations of metal ions in the plasma could be substantially reduced. This achievement is of particular importance for NI counter-injection and ICRH, where under non-carbonized conditions severe impurity problems occur. We studied impurity confinement in the case of various heating scenarios by means of the laser injection technique. The poorest confinement is found for the L-phase of NI. Metal injection into the high confinement H-phase generally causes temporary suppression of the edge localized modes (ELM's). With respect to ICRH we conclude that enhanced wall erosion — probably due to the production of high energy ions in the boundary — together with a slightly increased impurity confinement is the dominant reason for the increase of the metallic concentrations. Impurity sputtering as an alternative strong erosion process was experimentally ruled out.

  7. Spray forming process for producing molds, dies and related tooling

    DOEpatents

    McHugh, K.M.; Key, J.F.

    1998-02-17

    A method is disclosed for spray forming manufacturing of near-net-shape molds, dies and related toolings, wherein liquid material such as molten metal, metallic alloys, or polymers are atomized into fine droplets by a high temperature, high velocity gas and deposited onto a pattern. Quenching of the atomized droplets provides a heat sink, thereby allowing undercooled and partially solidified droplets to be formed in-flight. Composites can be formed by combining the atomized droplets with solid particles such as whiskers or fibers. 17 figs.

  8. Optical coefficients in a semiconductor quantum ring: Electric field and donor impurity effects

    NASA Astrophysics Data System (ADS)

    Duque, C. M.; Acosta, Ruben E.; Morales, A. L.; Mora-Ramos, M. E.; Restrepo, R. L.; Ojeda, J. H.; Kasapoglu, E.; Duque, C. A.

    2016-10-01

    The electron states in a two-dimensional quantum dot ring are calculated in the presence of a donor impurity atom under the effective mass and parabolic band approximations. The effect of an externally applied electric field is also taken into account. The wavefunctions are obtained via the exact diagonalization of the problem Hamiltonian using a 2D expansion within the adiabatic approximation. The impurity-related optical response is analyzed via the optical absorption, relative refractive index change and the second harmonics generation. The dependencies of the electron states and these optical coefficients with the changes in the configuration of the quantum ring system are discussed in detail.

  9. Articles which include chevron film cooling holes, and related processes

    SciTech Connect

    Bunker, Ronald Scott; Lacy, Benjamin Paul

    2014-12-09

    An article is described, including an inner surface which can be exposed to a first fluid; an inlet; and an outer surface spaced from the inner surface, which can be exposed to a hotter second fluid. The article further includes at least one row or other pattern of passage holes. Each passage hole includes an inlet bore extending through the substrate from the inlet at the inner surface to a passage hole-exit proximate to the outer surface, with the inlet bore terminating in a chevron outlet adjacent the hole-exit. The chevron outlet includes a pair of wing troughs having a common surface region between them. The common surface region includes a valley which is adjacent the hole-exit; and a plateau adjacent the valley. The article can be an airfoil. Related methods for preparing the passage holes are also described.

  10. Adsorption equilibrium and kinetics for multiple trace impurities in various gas streams on activated carbon

    SciTech Connect

    Golden, T.C.; Kumar, R. )

    1993-01-01

    Equilibrium and kinetic adsorption data for seven trace impurities (propylene, Freon-12 (CF[sub 2]Cl[sub 2]), n-butane, methylene chloride, acetone, n-hexane, toluene, and Freon-22 (CHFCl[sub 2])) from various carrier gases (helium, nitrogen, methane, carbon dioxide, and a mixture of methane and carbon dioxide) are provided. Activated carbon at several temperatures and pressures is used as the adsorbent. Two empirical characteristic curves, one relating equilibrium isotherms of trace impurities with their physical properties and the other relating mass-transfer coefficients with equilibrium properties, are generated. These can be used to predict equilibrium capacities and mass-transfer zone lengths for multiple trace impurities from a carrier gas and design a thermal swing adsorption clean-up system.

  11. Features of impurity photoconductivity in Si:Er/Si epitaxial diodes

    SciTech Connect

    Antonov, A. V.; Kudryavtsev, K. E. Shengurov, D. V.; Shmagin, V. B.; Krasilnik, Z. F.

    2013-11-15

    The photocurrent spectra of Si:Er/Si epitaxial diode structures are studied. It is shown that the nature of the sub-band-gap photoresponse is determined by the epitaxial growth temperature of the Si:Er layer and is not related to the composition of erbium emission centers. It is found that the absorption of light with photon energies lower than the energy-gap of silicon is determined by impurity-defect complexes that appear during the growth of the epitaxial layer and form a quasi-continuous spectrum of states in the energy gap of silicon. It is assumed that these impurity centers are not related to optically active erbium centers and are not involved in excitation-energy transfer to the rare-earth impurity.

  12. 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.

  13. 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.

  14. Power radiated from ITER and CIT by impurities

    SciTech Connect

    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. 22 refs., 16 figs.

  15. CO2-ECBM related coupled physical and mechanical transport processes

    NASA Astrophysics Data System (ADS)

    Gensterblum, Y.; Sartorius, M.; Busch, A.; Krooss, B. M.; Littke, R.

    2012-12-01

    The interrelation of cleat transport processes and mechanical properties was investigated by permeability tests at different stress levels (60% to 130% of in-situ stress) with sorbing (CH4, CO2) and inert gases (N2, Ar, He) on a subbituminous A coal from the Surat Basin, Queensland Australia (figure). From the flow tests under controlled triaxial stress conditions the Klinkenberg-corrected "true" permeability coefficients and the Klinkenberg slip factors were derived. The "true"-, absolute or Klinkenberg-corrected permeability depends on gas type. Following the approach of Seidle et al. (1992) the cleat volume compressibility (cf) was calculated from observed changes in apparent permeability upon variation of external stress (at equal mean gas pressures). The observed effects also show a clear dependence on gas type. Due to pore or cleat compressibility the cleat aperture decreases with increasing effective stress. Vice versa, with increasing mean pore pressure at lower confining pressure an increase in permeability is observed, which is attributed to a widening of cleat aperture. Non-sorbing gases like helium and argon show higher apparent permeabilities than sorbing gases like methane and CO2. Permeability coefficients measured with successively increasing mean gas pressures were consistently lower than those determined at decreasing mean gas pressures. The kinetics of matrix transport processes were studied by sorption tests on different particle sizes at various moisture contents and temperatures (cf. Busch et al., 2006). Methane uptake rates were determined from the pressure decline curves recorded for each particle-size fraction, and "diffusion coefficients" were calculated using several unipore and bidisperse diffusion models. While the CH4 sorption capacity of moisture-equilibrated coals was significantly lower (by 50%) than that of dry coals, no hysteresis was observed between sorption and desorption on dry and moisture-equilibrated samples and the

  16. Biological Processes Related to Serpentinization: Expected vs Observed Patterns

    NASA Astrophysics Data System (ADS)

    Cardace, D.

    2015-12-01

    Serpentinization is a water-rock reaction that drives the evolution of micro- to mega-scale habitability in ultramafic rocks, through the aqueous alteration of olivine and pyroxene in parent rocks, and the production of H2, CH4, and (possibly) biologically useful organic compounds. This process may pervade extensive areas of silicate planetary bodies, in geologic settings as diverse as cratered fracture zones and fault systems in ultramafic rocks, hydrothermal flow systems operating near crust/mantle interfaces, and deep subsurface groundwater flow systems. Serpentinization causes transformations in mineralogy, rock geochemistry, and co-occurring associated water chemistry that together control the feasibilities of prominent microbial metabolisms. Changing activities of aqueous H2, CH4, CO2, CO, organic acids, H+, and other redox-sensitive dissolved species shift the metabolic landscape in serpentinites in predictable ways, providing expected patterns in community metabolic strategies. I discuss emerging patterns in observations from terrestrial sites of serpentinization, marine and continent-hosted, and consider how they may allow testing of some pertinent hypotheses in geomicrobiology in terrestrial and extraterrestrial settings.

  17. Hypoxia-related processes in the Baltic Sea.

    PubMed

    Conley, Daniel J; Björck, Svante; Bonsdorff, Erik; Carstensen, Jacob; Destouni, Georgia; Gustafsson, Bo G; Hietanen, Susanna; Kortekaas, Marloes; Kuosa, Harri; Meier, H E Markus; Müller-Karulis, Baerbel; Nordberg, Kjell; Norkko, Alf; Nürnberg, Gertrud; Pitkänen, Heikki; Rabalais, Nancy N; Rosenberg, Rutger; Savchuk, Oleg P; Slomp, Caroline P; Voss, Maren; Wulff, Fredrik; Zillén, Lovisa

    2009-05-15

    Hypoxia, a growing worldwide problem, has been intermittently present in the modern Baltic Sea since its formation ca. 8000 cal. yr BP. However, both the spatial extent and intensity of hypoxia have increased with anthropogenic eutrophication due to nutrient inputs. Physical processes, which control stratification and the renewal of oxygen in bottom waters, are important constraints on the formation and maintenance of hypoxia. Climate controlled inflows of saline water from the North Sea through the Danish Straits is a critical controlling factor governing the spatial extent and duration of hypoxia. Hypoxia regulates the biogeochemical cycles of both phosphorus (P) and nitrogen (N) in the water column and sediments. Significant amounts of P are currently released from sediments, an order of magnitude larger than anthropogenic inputs. The Baltic Sea is unique for coastal marine ecosystems experiencing N losses in hypoxic waters below the halocline. Although benthic communities in the Baltic Sea are naturally constrained by salinity gradients, hypoxia has resulted in habitat loss over vast areas and the elimination of benthic fauna, and has severely disrupted benthic food webs. Nutrient load reductions are needed to reduce the extent, severity, and effects of hypoxia. PMID:19544833

  18. Spin pumping through magnetic impurity effect

    NASA Astrophysics Data System (ADS)

    Deng, Wei-Yin; Sheng, Li; Xing, Ding-Yu

    2015-08-01

    We propose a simple adiabatic quantum spin pump to generate pure spin current. The spin pump is driven by an ac gate voltage and a time-dependent magnetic impurity potential. It is found that the total pumped spin per cycle exhibits oscillations, whose magnitude decays exponentially with changing strength of the impurity potential. The proposed method may be useful for spintronic applications. Project supported by the State Key Program for Basic Research of China (Grant Nos. 2015CB921202, 2014CB921103, 2011CB922103, and 2010CB923400), the National Natural Science Foundation of China (Grant Nos. 11225420, 11174125, and 91021003), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

  19. DIET Processes on Ruthenium Surfaces Related to Extreme Ultraviolet Lithography (EUVL)

    SciTech Connect

    Yakshinskiy, B.; Wasielewski, R; Loginova, E; Hedhili, M; Madey, T

    2008-01-01

    The aim of this work is to provide insights into desorption induced by electronic transitions (DIET) processes that affect the reflectivity of ruthenium-capped Mo/Si multilayer mirrors working under EUVL (extreme ultraviolet lithography) operating conditions (high vacuum, and 13.5 nm (92 eV) photons). Critical issues are associated with possible oxidation of the 2 nm thick Ru capping layer due to the inevitable background pressure of H{sub 2}O, and carbon build up due to background hydrocarbons. In the present work, we discuss aspects of the radiation-induced surface chemistry of Ru irradiated by 100 eV electrons and 92 eV photons. The cross section for electron-stimulated desorption of oxygen from O-covered Ru is 6 x 10{sup -19} cm{sup 2}. Carbon accumulation several nm thick occurs on the Ru surface during electron irradiation in methyl methacrylate (MMA) vapor, a model background impurity hydrocarbon. Radiation damage by low-energy secondary electrons is believed to dominate over direct photoexcitation of adsorbates under EUVL conditions. The secondary electron yield from Ru varies strongly with photon energy, and is 0.02 electrons/photon at 92 eV.

  20. DIET processes on ruthenium surfaces related to extreme ultraviolet lithography (EUVL)

    NASA Astrophysics Data System (ADS)

    Yakshinskiy, B. V.; Wasielewski, R.; Loginova, E.; Hedhili, M. N.; Madey , T. E.

    2008-10-01

    The aim of this work is to provide insights into desorption induced by electronic transitions (DIET) processes that affect the reflectivity of ruthenium-capped Mo/Si multilayer mirrors working under EUVL (extreme ultraviolet lithography) operating conditions [high vacuum, and 13.5 nm (92 eV) photons]. Critical issues are associated with possible oxidation of the 2 nm thick Ru capping layer due to the inevitable background pressure of H 2O, and carbon build up due to background hydrocarbons. In the present work, we discuss aspects of the radiation-induced surface chemistry of Ru irradiated by 100 eV electrons and 92 eV photons. The cross section for electron-stimulated desorption of oxygen from O-covered Ru is ˜6 × 10 -19 cm 2. Carbon accumulation several nm thick occurs on the Ru surface during electron irradiation in methyl methacrylate (MMA) vapor, a model background impurity hydrocarbon. Radiation damage by low-energy secondary electrons is believed to dominate over direct photoexcitation of adsorbates under EUVL conditions. The secondary electron yield from Ru varies strongly with photon energy, and is ˜0.02 electrons/photon at 92 eV.

  1. 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.

  2. CO2-ECBM related coupled physical and mechanical transport processes

    NASA Astrophysics Data System (ADS)

    Gensterblum, Yves; Satorius, Michael; Busch, Andreas; Krooß, Bernhard

    2013-04-01

    The interrelation of cleat transport processes and mechanical properties was investigated by permeability tests at different stress levels (60% to 130% of in-situ stress) with sorbing (CH4, CO2) and inert gases (N2, Ar, He) on a sub bituminous A coal from the Surat Basin, Queensland Australia. From the flow tests under controlled triaxial stress conditions the Klinkenberg-corrected "true" permeability coefficients and the Klinkenberg slip factors were derived. The "true"-, absolute or Klinkenberg corrected permeability shows a gas type dependence. Following the approach of Seidle et al. (1992) the cleat volume compressibility (cf) was calculated from observed changes in apparent permeability upon variation of external stress (at equal mean gas pressures). The observed effects also show a clear dependence on gas type. Due to pore or cleat compressibility the cleat aperture decreases with increasing effective stress. Vice versa we observe with increasing mean pressure at lower confining pressure an increase in permeability which we attribute to a cleat aperture widening. The cleat volume compressibility (cf) also shows a dependence on the mean pore pressure. Non-sorbing gases like helium and argon show higher apparent permeabilities than sorbing gases like methane. Permeability coefficients measured with successively increasing mean gas pressures were consistently lower than those determined at decreasing mean gas pressures. This permeability hysteresis is in accordance with results reported by Harpalani and McPherson (1985). The kinetics of matrix transport processes were studied by sorption tests on different particle sizes at various moisture contents and temperatures (cf. Busch et al., 2006). Methane uptake rates were determined from the pressure decline curves recorded for each particle-size fraction, and "diffusion coefficients" were calculated using several unipore and bidisperse diffusion models. While the CH4 sorption capacity of moisture-equilibrated coals

  3. CO2-ECBM related coupled physical and mechanical transport processes

    NASA Astrophysics Data System (ADS)

    Gensterblum, Y.; Sartorius, M.; Busch, A.; Cumming, D.; Krooss, B. M.

    2012-04-01

    The interrelation of cleat transport processes and mechanical properties was investigated by permeability tests at different stress levels (60% to 130% of in-situ stress) with sorbing (CH4, CO2) and inert gases (N2, Ar, He) on a sub bituminous A coal from the Surat Basin, Queensland Australia. From the flow tests under controlled triaxial stress conditions the Klinkenberg-corrected "true" permeability coefficients and the Klinkenberg slip factors were derived. The "true"-, absolute or Klinkenberg corrected permeability shows a gas type dependence. Following the approach of Seidle et al. (1992) the cleat volume compressibility (cf) was calculated from observed changes in apparent permeability upon variation of external stress (at equal mean gas pressures). The observed effects also show a clear dependence on gas type. Due to pore or cleat compressibility the cleat aperture decreases with increasing effective stress. Vice versa we observe with increasing mean pressure at lower confining pressure an increase in permeability which we attribute to a cleat aperture widening. The cleat volume compressibility (cf) also shows a dependence on the mean pore pressure. Non-sorbing gases like helium and argon show higher apparent permeabilities than sorbing gases like methane. Permeability coefficients measured with successively increasing mean gas pressures were consistently lower than those determined at decreasing mean gas pressures. This permeability hysteresis is in accordance with results reported by Harpalani and McPherson (1985). The kinetics of matrix transport processes were studied by sorption tests on different particle sizes at various moisture contents and temperatures (cf. Busch et al., 2006). Methane uptake rates were determined from the pressure decline curves recorded for each particle-size fraction, and "diffusion coefficients" were calculated using several unipore and bidisperse diffusion models. While the CH4 sorption capacity of moisture-equilibrated coals

  4. PROCESS FOR TREATING VOLATILE METAL FLUORIDES

    DOEpatents

    Rudge, A.J.; Lowe, A.J.

    1957-10-01

    This patent relates to the purification of uranium hexafluoride, made by reacting the metal or its tetrafluoride with fluorine, from the frequently contained traces of hydrofluoric acid. According to the present process, UF/sub 6/ containing as an impurity a small amount of hydrofluoric acid, is treated to remove such impurity by contact with an anhydrous alkali metal fluoride such as sodium fluoride. In this way a non-volatile complex containing hydrofluoric acid and the alkali metal fluoride is formed, and the volatile UF /sub 6/ may then be removed by distillation.

  5. Cross-type spectrum rearrangement in graphene with weakly bound impurity centres: an impurity band with anomalous dispersion.

    PubMed

    Skrypnyk, Yuriy V; Loktev, Vadim M

    2013-05-15

    It is demonstrated that an anomalous dispersion region appears in the energy spectrum of charge carriers in graphene on increasing the concentration of weakly bound impurity centres. The corresponding spectrum rearrangement evolves in the neighbourhood of the impurity resonance energy and is of the cross type. The opening of the anomalous dispersion region in the impure graphene is accompanied by a doubling of the number of Dirac points in its electron spectrum. The stated spectrum rearrangement unfolds in a threshold manner, i.e. it takes place when the impurity concentration exceeds a certain critical value, which is determined by the mutual spatial overlap of individual impurity states.

  6. Variable Charge State Impurities in Coupled Kinetic Plasma-Kinetic Neutral Transport Simulations

    NASA Astrophysics Data System (ADS)

    Stotler, D. P.; Hager, R.; Kim, K.; Koskela, T.; Park, G.

    2015-11-01

    A previous version of the XGC0 neoclassical particle transport code with two fully stripped impurity species was used to study kinetic neoclassical transport in the DIII-D H-mode pedestal. To properly simulate impurities in the scrape-off layer and divertor and to account for radiative cooling, however, the impurity charge state distributions must evolve as the particles are transported into regions of different electron temperatures and densities. To do this, the charge state of each particle in XGC0 is included as a parameter in the list that represents the particle's location in phase space. Impurity ionizations and recombinations are handled with a dedicated collision routine. The associated radiative cooling is accumulated during the process and applied to the electron population later in the time step. The density profiles of the neutral impurities are simulated with the DEGAS 2 neutral transport code and then used as a background for electron impact ionization in XGC0 via a test particle Monte Carlo method analogous to that used for deuterium. This work supported by US DOE contracts DE-AC02-09CH11466.

  7. Radiated Power and Impurity Concentrations in the EXTRAP-T2R Reversed-Field Pinch

    NASA Astrophysics Data System (ADS)

    Corre, Y.; Rachlew, E.; Cecconello, M.; Gravestijn, R. M.; Hedqvist, A.; Pégourié, B.; Schunke, B.; Stancalie, V.

    2005-01-01

    A numerical and experimental study of the impurity concentration and radiation in the EXTRAP-T2R device is reported. The experimental setup consists of an 8-chord bolometer system providing the plasma radiated power and a vacuum-ultraviolet spectrometer providing information on the plasma impurity content. The plasma emissivity profile as measured by the bolometric system is peaked in the plasma centre. A one dimensional Onion Skin Collisional-Radiative model (OSCR) has been developed to compute the density and radiation distributions of the main impurities. The observed centrally peaked emissivity profile can be reproduced by OSCR simulations only if finite particle confinement time and charge-exchange processes between plasma impurities and neutral hydrogen are taken into account. The neutral hydrogen density profile is computed with a recycling code. Simulations show that recycling on metal first wall such as in EXTRAP-T2R (stainless steel vacuum vessel and molybdenum limiters) is compatible with a rather high neutral hydrogen density in the plasma centre. Assuming an impurity concentration of 10% for oxygen and 3% for carbon compared with the electron density, the OSCR calculation including lines and continuum emission reproduces about 60% of the total radiated power with a similarly centrally peaked emissivity profile. The centrally peaked emissivity profile is due to low ionisation stages and strongly radiating species in the plasma core, mainly O4+ (Be-like) and C3+ Li-like.

  8. 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.

  9. Effect of ion doping with donor and acceptor impurities on intensity and lifetime of photoluminescence from SiO2 films with silicon quantum dots.

    PubMed

    Mikhaylov, A N; Tetelbaum, D I; Burdov, V A; Gorshkov, O N; Belov, A I; Kambarov, D A; Belyakov, V A; Vasiliev, V K; Kovalev, A I; Gaponova, D M

    2008-02-01

    Doping with donor and acceptor impurities is an effective way to control light emission originated from quantum-size effect in Si nanocrystals. Combined measurements of photoluminescence intensity and kinetics give valuable information on mechanisms of the doping influence. Phosphorus, boron, and nitrogen were introduced by ion implantation into Si+ -implanted thermal SiO2 films either before or after synthesis of Si nanocrystals performed at Si excess of about 10 at.% and annealing temperatures of 1000 and 1100 degrees C. After the implantation of the impurity ions the samples were finally annealed at 1000 degrees C. It is found that, independently of ion kind, the ion irradiation (the first stage of the doping process) completely quenches the photoluminescence related to Si nanocrystals (peak at around 750 nm) and modifies visible luminescence of oxygen-deficient centers in the oxide matrix. The doping with phosphorus increases significantly intensity of the 750 nm photoluminescence excited by a pulse 337 nm laser for the annealing temperature of 1000 degrees C, while introduction of boron and nitrogen atoms reduces this emission for all the regimes used. In general, the effective lifetimes (ranging from 4 to 40 micros) of the 750 nm photoluminescence correlate with the photoluminescence intensity. Several factors such as radiation damage, influence of impurities on the nanocrystals formation, carrier-impurity interaction are discussed. The photoluminescence decay is dominated by the non-radiative processes due to formation or passivation of dangling bonds, whereas the intensity of photoluminescence (for excitation pulses much shorter than the photoluminescence decay) is mainly determined by the radiative lifetime. The influence of phosphorus doping on radiative recombination in Si quantum dots is analyzed theoretically.

  10. Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors.

    PubMed

    Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V

    2015-07-03

    The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm(2) cross-section. The impurities suppress superconductivity in a three-dimensional 'Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ∼1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.

  11. Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors

    NASA Astrophysics Data System (ADS)

    Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J.; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F.; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V.

    2015-07-01

    The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm2 cross-section. The impurities suppress superconductivity in a three-dimensional `Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ~1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.

  12. Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors

    PubMed Central

    Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J.; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F.; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V.

    2015-01-01

    The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm2 cross-section. The impurities suppress superconductivity in a three-dimensional ‘Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ∼1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities. PMID:26139568

  13. Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors.

    PubMed

    Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V

    2015-01-01

    The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm(2) cross-section. The impurities suppress superconductivity in a three-dimensional 'Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ∼1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities. PMID:26139568

  14. Impure CO2 geological storage: Preliminary laboratory experiments at ambient conditions

    NASA Astrophysics Data System (ADS)

    Oostrom, M.; Wei, N.; Wang, Y.; Zhang, C.; Bonneville, A.

    2011-12-01

    The cost of carbon capture is related to the purity of the CO2 and subsequent removal of the impurities may be costly. For several sites, it is likely to be more cost effective if impure CO2 is injected, although non-condensable impurities may reduce storage capacity and increase the injection pressure. The feasibility of co-sequestration of CO2 with a certain level of impurity has not been experimentally studied in much detail due to severe limitations associated with visualization and sampling at high pressure and temperature conditions. A series of intermediate-scale experiments has been conducted in a 100-cm-long, 20-cm-high, and 5-cm-wide intermediate-scale flow cell studying the effects of N2 and H2S impurities on CO2 transport in initially brine-saturated porous media. Homogeneous and simple layered heterogeneous systems were used to evaluate pH behavior, measure water and gas pressures, and analyze the gas composition at several locations. A multiphase code was used to compare simulation results for equilibrium dissolution conditions with experimental results. Although these preliminary analogue experiments were conducted at ambient pressure and temperature, the provide insight in the behavior of injected multi-component gas in initially saturated porous media.

  15. 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.

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

    DOE PAGES

    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

  17. 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

  18. Individual Differences in Spatial Relation Processing: Effects of Strategy, Ability, and Gender

    ERIC Educational Resources Information Center

    van der Ham, Ineke J. M.; Borst, Gregoire

    2011-01-01

    Numerous studies have focused on the distinction between categorical and coordinate spatial relations. Categorical relations are propositional and abstract, and often related to a left hemisphere advantage. Coordinate relations specify the metric information of the relative locations of objects, and can be linked to right hemisphere processing.…

  19. Incorporation and redistribution of impurities into silicon nanowires during metal-particle-assisted growth.

    PubMed

    Chen, Wanghua; Yu, Linwei; Misra, Soumyadeep; Fan, Zheng; Pareige, Philippe; Patriarche, Gilles; Bouchoule, Sophie; Roca i Cabarrocas, Pere

    2014-06-12

    The incorporation of metal atoms into silicon nanowires during metal-particle-assisted growth is a critical issue for various nanowire-based applications. Here we have been able to access directly the incorporation and redistribution of metal atoms into silicon nanowires produced by two different processes at growth rates ranging from 3 to 40 nm s(-1), by using laser-assisted atom probe tomography and scanning transmission electron microscopy. We find that the concentration of metal impurities in crystalline silicon nanowires increases with the growth rate and can reach a level of two orders of magnitude higher than that in their equilibrium solubility. Moreover, we demonstrate that the impurities are first incorporated into nanowire volume and then segregate at defects such as the twin planes. A dimer-atom-insertion kinetic model is proposed to account for the impurity incorporation into nanowires.

  20. Detection of subsurface trace impurity in polished fused silica with biological method.

    PubMed

    Wang, Zhuo; Wang, Lin; Yang, Junhong; Peng, Wenqiang; Hu, Hao

    2014-09-01

    Subsurface damage (SSD), especially photoactive impurities, degrades the performance of high energy optics by reduction in the laser induced damage threshold. As the polishing defects are trace content and lie beneath the surface, they are difficult to detect. We herein present a biological method to measure impurities on polished fused silica, based on the intense inhibiting ability about trace level of ceria on enzyme activity. And the enzyme activity is measured in the individual etching solutions of a sequential etching process. Results show that detectability of the biological method satisfies the needs of trace impurity detection with low cost and simple apparatus. Furthermore ceria can be used to tag SSD in lapped and polished optics. PMID:25321508

  1. The role of MHD in causing impurity peaking in JET hybrid plasmas

    NASA Astrophysics Data System (ADS)

    Hender, T. C.; Buratti, P.; Casson, F. J.; Alper, B.; Baranov, Yu. F.; Baruzzo, M.; Challis, C. D.; Koechl, F.; Lawson, K. D.; Marchetto, C.; Nave, M. F. F.; Pütterich, T.; Reyes Cortes, S.; Contributors, JET

    2016-06-01

    In hybrid plasma operation in JET with its ITER-like wall (JET-ILW) it is found that n  >  1 tearing activity can significantly enhance the rate of on-axis peaking of high-Z impurities, which in turn significantly degrades discharge performance. Core n  =  1 instabilities can be beneficial in removing impurities from the plasma core (e.g. sawteeth or fishbones), but can conversely also degrade core confinement (particularly in combination with simultaneous n  =  3 activity). The nature of magnetohydrodynamic instabilities in JET hybrid discharges, with both its previous carbon wall and subsequent JET-ILW, is surveyed statistically and the character of the instabilities is examined. Possible qualitative models for how the n  >  1 islands can enhance the on-axis impurity transport accumulation processes are presented.

  2. Oxide impurities in silicon oxide intermetal dielectrics and their potential to elevate via-resistances.

    PubMed

    Qin, Wentao; Alldredge, Donavan; Heleotes, Douglas; Elkind, Alexander; Theodore, N David; Fejes, Peter; Vadipour, Mostafa; Godek, Bill; Lerner, Norman

    2014-08-01

    Silicon oxide used as an intermetal dielectric (IMD) incorporates oxide impurities during both its formation and subsequent processing to create vias in the IMD. Without a sufficient degassing of the IMD, oxide impurities released from the IMD during the physical vapor deposition (PVD) of the glue layer of the vias had led to an oxidation of the glue layer and eventual increase of the via resistances, which correlated with the O-to-Si atomic ratio of the IMD being ~10% excessive as verified by transmission electron microscopy (TEM) analysis. A vacuum bake of the IMD was subsequently implemented to enhance outgassing of the oxide impurities in the IMD before the glue layer deposition. The implementation successfully reduced the via resistances to an acceptable level.

  3. Phonon sidebands of excitons bound to isoelectronic impurities in semiconductors

    SciTech Connect

    Zhang, Y.; Ge, W.; Sturge, M.D. ); Zheng, J.; Wu, B. )

    1993-03-15

    The configuration coordinate (CC) and momentum conservation (MC) models have been widely used to explain the phonon sidebands of impurity spectra in semiconductors. In this paper, the distinction between the CC and MC models is discussed. We conclude that the MC model only applies to shallow Coulombic impurities; in other cases, such as isoelectronic traps, the CC model is more appropriate. We show that the Huang-Rhys parameters for bulk phonon modes coupling to a bound electron or exciton can be calculated from the bound-state wave function in [ital k] space if the phonon-induced intervalley and intravalley electron scattering processes of the pure crystal are known. We study in detail the phonon sidebands of nitrogen-bound excitons in GaP, giving the selection rules for electron-phonon coupling in the CC model, and showing that their strength can be well accounted for by the CC model. The apparently anomalous [ital X]'' peak of the LO-phonon sideband in GaP:N is shown to be associated with intervalley scattering in the conduction band. The MC model, which has been used in an attempt to explain the phonon sidebands of GaP:N in some previous work, is shown to be inapplicable to this case.

  4. 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

  5. Classroom Terraria: Enhancing Student Understanding of Plant-Related Gas Processes

    ERIC Educational Resources Information Center

    Thompson, Stephen

    2010-01-01

    Despite our best teaching efforts, many students hold misconceptions related to the roles plants play in gas-related processes (Amir and Tamir 1994; Hershey 1992; 2004). In an effort to remedy this problem, the author presents a series of activities that address common plant-related gas-process misconceptions held by middle school students. The…

  6. The impact of multi-walled carbon nanotubes with different amount of metallic impurities on immunometabolic parameters in healthy volunteers.

    PubMed

    Vitkina, T I; Yankova, V I; Gvozdenko, T A; Kuznetsov, V L; Krasnikov, D V; Nazarenko, A V; Chaika, V V; Smagin, S V; Tsatsakis, A Μ; Engin, A B; Karakitsios, S P; Sarigiannis, D A; Golokhvast, K S

    2016-01-01

    The impact of two types of multi-walled carbon nanotubes (MWCNTs) (12-14 nm) with different content of metallic impurities (purified and unpurified nanotubes) on peroxidation processes, the status of immune cells in healthy volunteers and gene expression combined to pathway analysis was studied in vitro. From the study it was shown that the main mechanism of action for both types of MWCNTs is induction of oxidative stress, the intensity of which is directly related to the amount of metallic impurities. Unpurified MWCNTs produced twice as high levels of oxidation than the purified CNTs inducing thus more intense mitochondrial dysfunction. All the above were also verified by gene expression analysis of 2 different human cellular cultures (lung epithelium and keratinoma cells) and the respective pathway analysis; modulation of genes activating the NFkB pathway is associated to inflammatory responses. This may cause a perturbation in the IL-6 signaling pathway in order to regulate inflammatory processes and compensate for apoptotic changes. A plausible hypothesis for the immunological effects observed in vivo, are considered as the result of the synergistic effect of systemic (mediated by cells of the routes of exposure) and local inflammation (blood cells).

  7. The impact of multi-walled carbon nanotubes with different amount of metallic impurities on immunometabolic parameters in healthy volunteers.

    PubMed

    Vitkina, T I; Yankova, V I; Gvozdenko, T A; Kuznetsov, V L; Krasnikov, D V; Nazarenko, A V; Chaika, V V; Smagin, S V; Tsatsakis, A Μ; Engin, A B; Karakitsios, S P; Sarigiannis, D A; Golokhvast, K S

    2016-01-01

    The impact of two types of multi-walled carbon nanotubes (MWCNTs) (12-14 nm) with different content of metallic impurities (purified and unpurified nanotubes) on peroxidation processes, the status of immune cells in healthy volunteers and gene expression combined to pathway analysis was studied in vitro. From the study it was shown that the main mechanism of action for both types of MWCNTs is induction of oxidative stress, the intensity of which is directly related to the amount of metallic impurities. Unpurified MWCNTs produced twice as high levels of oxidation than the purified CNTs inducing thus more intense mitochondrial dysfunction. All the above were also verified by gene expression analysis of 2 different human cellular cultures (lung epithelium and keratinoma cells) and the respective pathway analysis; modulation of genes activating the NFkB pathway is associated to inflammatory responses. This may cause a perturbation in the IL-6 signaling pathway in order to regulate inflammatory processes and compensate for apoptotic changes. A plausible hypothesis for the immunological effects observed in vivo, are considered as the result of the synergistic effect of systemic (mediated by cells of the routes of exposure) and local inflammation (blood cells). PMID:26683310

  8. Isolation, Identification, and Characterization of an Unknown Impurity in Lovastatin EP.

    PubMed

    Belwal, Chandrakant; Goyal, Praveen Kumar; Balte, Anup; Kolhe, Sandeep; Chauhan, Kamlesh; Rawat, Ajay Singh; Vardhan, Anand

    2014-03-01

    An unknown impurity in the fermentation-based drug substance lovastatin at 0.52 RRT was observed invariably in all batches when analyzed by HPLC as per the PhEur monograph. This impurity was isolated from the impurity-enriched sample using reversed-phase preparative HPLC and characterized by using spectroscopic (PMR, CMR, MASS, and UV) techniques as the structurally-related compound Monacolin-X, having the molecular formula C24H34O6 and the chemical name 2-methyl-3-oxobutanoic acid 1,2,3,7,8,8a-hexahydro-3,7-dimethyl-8-[2-(tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl)ethyl]-1-naphthalenyl ester. PMID:24634841

  9. Chemically reduced graphene contains inherent metallic impurities present in parent natural and synthetic graphite

    PubMed Central

    Ambrosi, Adriano; Chua, Chun Kiang; Khezri, Bahareh; Sofer, Zdeněk; Webster, Richard D.; Pumera, Martin

    2012-01-01

    Graphene-related materials are in the forefront of nanomaterial research. One of the most common ways to prepare graphenes is to oxidize graphite (natural or synthetic) to graphite oxide and exfoliate it to graphene oxide with consequent chemical reduction to chemically reduced graphene. Here, we show that both natural and synthetic graphite contain a large amount of metallic impurities that persist in the samples of graphite oxide after the oxidative treatment, and chemically reduced graphene after the chemical reduction. We demonstrate that, despite a substantial elimination during the oxidative treatment of graphite samples, a significant amount of impurities associated to the chemically reduced graphene materials still remain and alter their electrochemical properties dramatically. We propose a method for the purification of graphenes based on thermal treatment at 1,000 °C in chlorine atmosphere to reduce the effect of such impurities on the electrochemical properties. Our findings have important implications on the whole field of graphene research. PMID:22826262

  10. Internal oxidation of sp-Impurities in silver studied by119Sn Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Andreasen, H.; Damgaard, S.; Nielsen, H. L.; Petersen, J. W.; Weyer, G.

    1983-12-01

    The internal oxidation of the ion-implanted radioactive precursors119Cd and119Sb to the Mössbauer isotope119Sn in silver has been investigated. The oxidation is monitored by the intensity of a line in the Mössbauer spectra, which is characteristic of SnO2 (δ=(0 0.23)mm/s relative to CaSnO3, ΔEQ ≈ 0.5 mm/s, ϑ ≈ 220 K). This line is attributed to an internal oxidation of the implanted impurities by interstitially diffusing oxygen pairs. The formation and annealing kinetics of the impurity-oxygen complexes are interpreted in terms of the diffusion coefficients of oxygen and the sp-impurities in silver, respectively, and the reactivity between them. Comparison is made to Mössbauer experiments on SnAg alloys and to PAC measurements on111cd in silver.

  11. Chemically reduced graphene contains inherent metallic impurities present in parent natural and synthetic graphite.

    PubMed

    Ambrosi, Adriano; Chua, Chun Kiang; Khezri, Bahareh; Sofer, Zdeněk; Webster, Richard D; Pumera, Martin

    2012-08-01

    Graphene-related materials are in the forefront of nanomaterial research. One of the most common ways to prepare graphenes is to oxidize graphite (natural or synthetic) to graphite oxide and exfoliate it to graphene oxide with consequent chemical reduction to chemically reduced graphene. Here, we show that both natural and synthetic graphite contain a large amount of metallic impurities that persist in the samples of graphite oxide after the oxidative treatment, and chemically reduced graphene after the chemical reduction. We demonstrate that, despite a substantial elimination during the oxidative treatment of graphite samples, a significant amount of impurities associated to the chemically reduced graphene materials still remain and alter their electrochemical properties dramatically. We propose a method for the purification of graphenes based on thermal treatment at 1,000 °C in chlorine atmosphere to reduce the effect of such impurities on the electrochemical properties. Our findings have important implications on the whole field of graphene research.

  12. Impurity Screening in Ohmic and H-Mode Plasmas in the Alcator C-Mod Tokamak^*

    NASA Astrophysics Data System (ADS)

    McCracken, G. M.

    1996-11-01

    The impurity density in the confined plasma is determined not only by the impurity production rate but also by screening, i.e. the balance between the perpendicular and parallel transport in the SOL. The relative importance of screening has been studied by injecting gaseous recycling (Ne, Ar) and non-recycling impurities (N, C) into various poloidal positions of the SOL and divertor in C-Mod. The density of the non-recycling impurities in the core is a function of the poloidal position of injection, while the screening of recycling impurities is not. In both cases screening is significantly worse ( ~3x) during divertor detachment. For a given injection rate of N2 gas into H-mode discharges, the number of impurities in the core is typically a factor of 3 greater than for ohmic discharges. Optical imaging of low charge states of the injected non-recycling impurities using a camera and spectral filters shows a directed plume, indicating flow of impurities towards the divertor target at all positions studied, even at the inboard midplane. This implies that the friction force due to plasma flow dominates the parallel ion temperature gradient force. The spatial distribution of low charge states in the divertor has been studied using a multichord visible spectrometer, and the distribution of the nitrogen radiation has been been studied using a 20 chord bolometer array. The results show that for attached discharges the nitrogen radiation is predominantly in the SOL below the X-point. The position of the radiation is not strongly dependent on the position of nitrogen injection. The screening has been compared with calculations using the DIVIMP Monte Carlo code [1] and with an analytical model of the impurity transport. Work supported by U.S. DOE Contract No. DE-AC02-78ET51013. În collaboration with B Lipschultz, B LaBombard, J A Goetz, R Granetz, D Jablonski, H Ohkawa, J Terry, MIT, S Lisgo, P C Stangeby, University of Toronto, ^1P.C. Stangeby and D. Elder, J. Nucl. Mater

  13. Experimental observations and model calculations of impurity radiation in a plasma gun compact torus experiment

    SciTech Connect

    Goldenbaum, G.C.; Granneman, E.H.A.; Hartman, C.W.; Prono, D.S.; Taska, J.; Turner, W.C.

    1982-08-10

    Several types of radiation measurements were performed on the Beta II compact forms experiment. Among these are time integrated spectra ranging in wavelength from the vuv to the uv, time resolved bolometer measurements of radiation from the x-ray to the infrared, and time and wavelength resolved measurements of certain spectral lines. It is difficult to relate any one of these measurements to plasma parameters of interest such as temperature, density, or impurity content. In this report we compare the results of these, and other measurements with two simple models of the power balance in the plasma in order to estimate the effect of carbon and oxygen impurities on plasma lifetime.

  14. IDENTIFYING IMPURITIES IN SURPLUS NON PIT PLUTONIUM FEEDS FOR MOX OR ALTERNATIVE DISPOSITION

    SciTech Connect

    Allender, J; Moore, E

    2010-07-14

    This report provides a technical basis for estimating the level of corrosion products in materials stored in DOE-STD-3013 containers based on extrapolating available chemical sample results. The primary focus is to estimate the levels of nickel, iron, and chromium impurities in plutonium-bearing materials identified for disposition in the United States Mixed Oxide fuel process.

  15. 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.

  16. Adaptive, maladaptive, mediational, and bidirectional processes of relational and physical aggression, relational and physical victimization, and peer liking.

    PubMed

    Kawabata, Yoshito; Tseng, Wan-Ling; Crick, Nicki R

    2014-01-01

    A three-wave longitudinal study among ethnically diverse preadolescents (N = 597 at Time 1, ages 9-11) was conducted to examine adaptive, maladaptive, mediational, and bidirectional processes of relational and physical aggression, victimization, and peer liking indexed by peer acceptance and friendships. A series of nested structural equation models tested the hypothesized links among these peer-domain factors. It was hypothesized that (1) relational aggression trails both adaptive and maladaptive processes, linking to more peer victimization and more peer liking, whereas physical aggression is maladaptive, resulting in more peer victimization and less peer liking; (2) physical and relational victimization is maladaptive, relating to more aggression and less peer liking; (3) peer liking may be the social context that promotes relational aggression (not physical aggression), whereas peer liking may protect against peer victimization, regardless of its type; and (4) peer liking mediates the link between forms of aggression and forms of peer victimization. Results showed that higher levels of peer liking predicted relative increases in relational aggression (not physical aggression), which in turn led to more peer liking. On the other hand, more peer liking was predictive of relative decreases in relational aggression and relational victimization in transition to the next grade (i.e., fifth grade). In addition, relational victimization predicted relative increases in relational aggression and relative decreases in peer liking. Similarly, physical aggression was consistently and concurrently associated more physical victimization and was marginally predictive of relative increases in physical victimization in transition to the next grade. More peer liking predicted relative decreases in physical victimization, which resulted in lower levels of peer liking. The directionality and magnitude of these paths did not differ between boys and girls.

  17. Far-Infrared Blocked Impurity Band Detector Development

    NASA Technical Reports Server (NTRS)

    Hogue, H. H.; Guptill, M. T.; Monson, J. C.; Stewart, J. W.; Huffman, J. E.; Mlynczak, M. G.; Abedin, M. N.

    2007-01-01

    DRS Sensors & Targeting Systems, supported by detector materials supplier Lawrence Semiconductor Research Laboratory, is developing far-infrared detectors jointly with NASA Langley under the Far-IR Detector Technology Advancement Partnership (FIDTAP). The detectors are intended for spectral characterization of the Earth's energy budget from space. During the first year of this effort we have designed, fabricated, and evaluated pilot Blocked Impurity Band (BIB) detectors in both silicon and germanium, utilizing pre-existing customized detector materials and photolithographic masks. A second-year effort has prepared improved silicon materials, fabricated custom photolithographic masks for detector process, and begun detector processing. We report the characterization results from the pilot detectors and other progress.

  18. Limiter/vacuum system for plasma impurity control and exhaust in tokamaks

    SciTech Connect

    Abdou, M.; Brooks, J.; Mattas, R.

    1980-01-01

    A detailed design of a limiter/vacuum system for plasma impurity control and exhaust has been developed for the STARFIRE tokamak power plant. It is shown that the limiter/vacuum concept is a very attractive option for power reactors. It is relatively simple and inexpensive and deserves serious experimental verification.

  19. Microscopic theory of dipole-dipole interaction in ensembles of impurity atoms in a Fabry-Perot cavity

    NASA Astrophysics Data System (ADS)

    Kuraptsev, A. S.; Sokolov, I. M.

    2016-08-01

    We develop a consistent quantum theory of the collective effects that take place when electromagnetic radiation interacts with a dense ensemble of impurity centers embedded in a transparent dielectric and placed in a Fabry-Perot cavity. We have calculated the spontaneous decay dynamics of an excited impurity atom as a specific example of applying the developed general theory. We analyze the dependence of the decay rate on the density of impurity centers and the sample sizes as well as on the characteristic level shifts of impurity atoms caused by the internal fields of the dielectric. We show that a cavity can affect significantly the pattern of collective processes, in particular, the lifetimes of collective states.

  20. Photoemission spectroscopy of magnetic and nonmagnetic impurities on the surface of the Bi2Se3 topological insulator.

    PubMed

    Valla, T; Pan, Z-H; Gardner, D; Lee, Y S; Chu, S

    2012-03-16

    Dirac-like surface states on surfaces of topological insulators have a chiral spin structure that suppresses backscattering and protects the coherence of these states in the presence of nonmagnetic scatterers. In contrast, magnetic scatterers should open the backscattering channel via the spin-flip processes and degrade the state's coherence. We present angle-resolved photoemission spectroscopy studies of the electronic structure and the scattering rates upon the adsorption of various magnetic and nonmagnetic impurities on the surface of Bi2Se3, a model topological insulator. We reveal a remarkable insensitivity of the topological surface state to both nonmagnetic and magnetic impurities in the low impurity concentration regime. Scattering channels open up with the emergence of hexagonal warping in the high-doping regime, irrespective of the impurity's magnetic moment.

  1. Controlled processes account for age-related decrease in episodic memory.

    PubMed

    Vanderaspoilden, Valérie; Adam, Stéphane; der Linden, Martial Van; Morais, José

    2007-05-01

    A decrease in controlled processes has been proposed to be responsible for age-related episodic memory decline. We used the Process Dissociation Procedure, a method that attempts to estimate the contribution of controlled and automatic processes to cognitive performance, and entered both estimates in regression analyses. Results indicate that only controlled processes explained a great part of the age-related variance in a word recall task, especially when little environmental support was offered. PMID:16860766

  2. Divertor impurity injection using high voltage arcs for impurity transport studies on the Mega Amp Spherical Tokamak

    SciTech Connect

    Leggate, H. J. Turner, M. M.; Lisgo, S. W.; Harrison, J. R.; Elmore, S.; Allan, S. Y.; Gaffka, R. C.; Stephen, R. C.

    2014-12-15

    The operation of next-generation fusion reactors will be significantly affected by impurity transport in the scrape-off layer (SOL). Current modelling efforts are restricted by a lack of detailed data on impurity transport in the SOL. In order to address this, a carbon injector has been designed and installed on the Mega Amp Spherical Tokamak (MAST). The injector creates short lived carbon plumes originating at the MAST divertor lasting less than 50 μs. High voltage capacitor banks are used to create a discharge across concentric carbon electrodes located in a probe mounted on the Divertor Science Facility in the MAST lower divertor. This results in a very short plume duration allowing observation of the evolution of the plume and precise localisation of the plume relative to the X-point on MAST. The emission from the carbon plume was imaged using fast visible cameras filtered in order to isolate the carbon II and carbon III emission lines centered around 514 nm and 465 nm.

  3. Divertor impurity injection using high voltage arcs for impurity transport studies on the Mega Amp Spherical Tokamak

    NASA Astrophysics Data System (ADS)

    Leggate, H. J.; Lisgo, S. W.; Harrison, J. R.; Elmore, S.; Allan, S. Y.; Gaffka, R. C.; Stephen, R. C.; Turner, M. M.

    2014-12-01

    The operation of next-generation fusion reactors will be significantly affected by impurity transport in the scrape-off layer (SOL). Current modelling efforts are restricted by a lack of detailed data on impurity transport in the SOL. In order to address this, a carbon injector has been designed and installed on the Mega Amp Spherical Tokamak (MAST). The injector creates short lived carbon plumes originating at the MAST divertor lasting less than 50 μs. High voltage capacitor banks are used to create a discharge across concentric carbon electrodes located in a probe mounted on the Divertor Science Facility in the MAST lower divertor. This results in a very short plume duration allowing observation of the evolution of the plume and precise localisation of the plume relative to the X-point on MAST. The emission from the carbon plume was imaged using fast visible cameras filtered in order to isolate the carbon II and carbon III emission lines centered around 514 nm and 465 nm.

  4. Divertor impurity injection using high voltage arcs for impurity transport studies on the Mega Amp Spherical Tokamak.

    PubMed

    Leggate, H J; Lisgo, S W; Harrison, J R; Elmore, S; Allan, S Y; Gaffka, R C; Stephen, R C; Turner, M M

    2014-12-01

    The operation of next-generation fusion reactors will be significantly affected by impurity transport in the scrape-off layer (SOL). Current modelling efforts are restricted by a lack of detailed data on impurity transport in the SOL. In order to address this, a carbon injector has been designed and installed on the Mega Amp Spherical Tokamak (MAST). The injector creates short lived carbon plumes originating at the MAST divertor lasting less than 50 μs. High voltage capacitor banks are used to create a discharge across concentric carbon electrodes located in a probe mounted on the Divertor Science Facility in the MAST lower divertor. This results in a very short plume duration allowing observation of the evolution of the plume and precise localisation of the plume relative to the X-point on MAST. The emission from the carbon plume was imaged using fast visible cameras filtered in order to isolate the carbon II and carbon III emission lines centered around 514 nm and 465 nm.

  5. A review of OSHA PSM citations relating to mechanical integrity of process piping

    SciTech Connect

    Casada, M.L.; Remson, A.C.; Yerger, C.M.

    1996-07-01

    OSHA`s process safety management (PSM) regulation has been in effect for more than three years. The regulation poses challenges for facilities in documenting the integrity of process piping systems. This paper summarizes the results of a project sponsored by the Materials Technology Institute (MTI) to compile PSM enforcement information relating to mechanical integrity W and process safety information (PSI) relating to equipment. This paper provides an analysis of how OSHA is citing violations of the PSM regulation as it relates to process piping. This information should be helpful to engineers and maintenance personnel who need guidance on how to ``OSHA-proof`` their mechanical integrity compliance for process piping systems.

  6. Entanglement in quantum impurity problems is nonperturbative

    NASA Astrophysics Data System (ADS)

    Saleur, H.; Schmitteckert, P.; Vasseur, R.

    2013-08-01

    We study the entanglement entropy of a region of length 2L with the remainder of an infinite one-dimensional gapless quantum system in the case where the region is centered on a quantum impurity. The coupling to this impurity is not scale invariant, and the physics involves a crossover between weak- and strong-coupling regimes. While the impurity contribution to the entanglement has been computed numerically in the past, little is known analytically about it, since in particular the methods of conformal invariance cannot be applied because of the presence of a crossover length. We show in this paper that the small coupling expansion of the entanglement entropy in this problem is quite generally plagued by strong infrared divergences, implying a nonperturbative dependence on the coupling. The large coupling expansion turns out to be better behaved, thanks to powerful results from the boundary CFT formulation and, in some cases, the underlying integrability of the problem. However, it is clear that this expansion does not capture well the crossover physics. In the integrable case—which includes problems such as an XXZ chain with a modified link, the interacting resonant level model or the anisotropic Kondo model—a nonperturbative approach is in principle possible using form factors. We adapt in this paper the ideas of Cardy [J. Stat. Phys.JSTPBS0022-471510.1007/s10955-007-9422-x 130, 129 (2008)] and Castro-Alvaredo and Doyon [J. Stat. Phys.JSTPBS0022-471510.1007/s10955-008-9664-2 134, 105 (2009)] to the gapless case and show that, in the rather simple case of the resonant level model, and after some additional renormalizations, the form-factors approach yields remarkably accurate results for the entanglement all the way from short to large distances. This is confirmed by detailed comparison with numerical simulations. Both our form factor and numerical results are compatible with a nonperturbative form at short distance.

  7. 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

  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. 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. Linear response of a one-dimensional conductor coupled to a dynamical impurity with a Fermi edge singularity

    NASA Astrophysics Data System (ADS)

    Snyman, I.

    2014-02-01

    I study the dynamical correlations that a quantum impurity induces in the Fermi sea to which it is coupled. I consider a quantum transport setup in which the impurity can be realized in a double quantum dot. The same Hamiltonian describes tunneling states in metallic glasses, and can be mapped onto the Ohmic spin-boson model. It exhibits a Fermi edge singularity, i.e., many fermion correlations result in an impurity decay rate with a nontrivial power-law energy dependence. I show that there is a simple relation between temporal impurity correlations on the one hand and the linear response of the Fermi sea to external perturbations on the other. This results in a power-law singularity in the space and time dependence of the nonlocal polarizability of the Fermi sea, which can be detected in transport experiments.

  11. Effects of Local and Global Context on Processing Sentences with Subject and Object Relative Clauses

    ERIC Educational Resources Information Center

    Yang, Fang; Mo, Lun; Louwerse, Max M.

    2013-01-01

    An eye tracking study investigated the effects of local and global discourse context on the processing of subject and object relative clauses, whereby the contexts favored either a subject relative clause interpretation or an object relative clause interpretation. The fixation data replicated previous studies showing that object relative clause…

  12. 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.

  13. Impurity and Defect Characterization in Silicon: Final Technical Report, 1 October 1991 - March 1992

    SciTech Connect

    Rohatgi, A.; Chen, Z.; Doolittle, W. A.; Salami, J.; Sana, P.

    1992-01-01

    The main objective of this research was to carry out an in-depth impurity analysis of polycrystalline samples, using techniques such as DLTS, FTIR, and light and dark I-V and correlate their effects on the photovoltaic parameters. The second object of this research was to understand the role of defect and gettering in polycrystalline silicon and develop processes for fabricating high efficiency polycrystalline cells using conventional process sequence and provide silicon solar cells to NREL for optically processed metallization.

  14. Renormalization-group calculation of excitation properties for impurity models

    NASA Astrophysics Data System (ADS)

    Yoshida, M.; Whitaker, M. A.; Oliveira, L. N.

    1990-05-01

    The renormalization-group method developed by Wilson to calculate thermodynamical properties of dilute magnetic alloys is generalized to allow the calculation of dynamical properties of many-body impurity Hamiltonians. As a simple illustration, the impurity spectral density for the resonant-level model (i.e., the U=0 Anderson model) is computed. As a second illustration, for the same model, the longitudinal relaxation rate for a nuclear spin coupled to the impurity is calculated as a function of temperature.

  15. Multichannel Kondo impurity dynamics in a Majorana device.

    PubMed

    Altland, A; Béri, B; Egger, R; Tsvelik, A M

    2014-08-15

    We study the multichannel Kondo impurity dynamics realized in a mesoscopic superconducting island connected to metallic leads. The effective "impurity spin" is nonlocally realized by Majorana bound states and strongly coupled to lead electrons by non-Fermi liquid correlations. We explore the spin dynamics and its observable ramifications near the low-temperature fixed point. The topological protection of the system raises the perspective to observe multichannel Kondo impurity dynamics in experimentally realistic environments.

  16. Local vibrational mode of an impurity in a monatomic linear chain under open and periodic boundary conditions

    NASA Astrophysics Data System (ADS)

    Luo, Qiang

    2016-11-01

    In this paper, we revisit the lattice vibration of a one-dimensional monatomic linear chain under open and periodic boundary conditions, and give the exact conditions for the emergence of the local vibration mode when one of the atoms is replaced by an impurity. Our motivation is twofold. Firstly, in deriving the dispersion relation of the atoms, the periodic boundary condition is overwhelmingly utilized while the open boundary condition is seldom used. Therefore we manage to obtain the dispersion relation under both boundary conditions simultaneously by the Molinari formula. Secondly, in the presence of an impurity, the local vibration mode can emerge as long as the mass of the impurity m\\prime is smaller than the mass of the perfect atom m to a certain degree, which can be measured by the mass ratio δ =\\tfrac{m-m\\prime }{m}. At the periodic boundary condition, the critical mass ratio is 0 or \\tfrac{1}{N}, depending on whether the length N of the chain is even or odd. At the open boundary condition, the critical mass ratio is \\tfrac{N}{2N-1} if the impurity locates at the end of the chain, while it is \\tfrac{N}{(2{N}{{l}}+1)(2{N}{{r}}+1)} with N l and N r the number of atoms at the left- and right-hand sides of the impurity if the impurity locates at the middle.

  17. Bridging intragroup processes and intergroup relations: needing the twain to meet.

    PubMed

    Dovidio, John F

    2013-03-01

    Despite their shared focus on groups, research bridging intragroup processes and intergroup relations is surprisingly rare. The goal of the present article is to highlight how understanding the reciprocal relationship between intragroup processes and intergroup relations offers valuable new insights into both topics and suggests new, productive avenues for research and theory development - particularly for understanding and improving intergroup relations. The article next briefly reviews key findings from three dominant frameworks in the field of intergroup relations: social cognition, social identity, and functional relations. It then discusses the complementary role of intergroup and intragroup dynamics, reviewing how intergroup relations can affect intragroup processes and then discussing how intragroup dynamics can shape intergroup relations. The final section considers the implications, theoretical and practical, of the proposed reciprocal relationships between intragroup and intergroup processes.

  18. Spectroscopic investigation of heavy impurity behaviour during ICRH with the JET ITER-like wall

    SciTech Connect

    Czarnecka, A.; Bobkov, V.; Maggi, C.; Pütterich, T.; Coffey, I. H.; Colas, L.; Jacquet, P.; Lawson, K. D.; Mayoral, M.-L. [Euratom Collaboration: JET-EFDA Contributors

    2014-02-12

    Magnetically confined plasmas, such as those produced in the tokamak JET, contain measurable amounts of impurity ions produced during plasma-wall interactions (PWI) from the plasma-facing components and recessed wall areas. The impurities, including high- and mid-Z elements such as tungsten (W) from first wall tiles and nickel (Ni) from Inconel structure material, need to be controlled within tolerable limits, to ensure they do not significantly affect the performance of the plasma. This contribution focuses on documenting W and Ni impurity behavior during Ion Cyclotron Resonance Heating (ICRH) operation with the new ITER-Like Wall (ILW). Ni- and W-concentration were derived from VUV spectroscopy and the impact of applied power level, relative phasing of the antenna straps, plasma separatrix - antenna strap distance, IC resonance position, edge density and different plasma configuration, on the impurity release during ICRH are presented. For the same ICRH power the Ni and W concentration was lower with dipole phasing than in the case of −π/2 phasing. The Ni concentration was found to increase with ICRH power and for the same NBI power level, ICRH-heated plasmas were characterized by two times higher Ni impurity content. Both W and Ni concentrations increased strongly with decreasing edge density which is equivalent to higher edge electron temperatures and more energetic ions responsible for the sputtering. In either case higher levels were found in ICRH than in NBI heated discharges. When the central plasma temperature was similar, ICRH on-axis heating resulted in higher core Ni impurity concentration in comparison to off-axis ICRH in L-mode. It was also found that the main core radiation during ICRH came from W.

  19. Impurity Gettering Effect of Te Inclusions in Cdznte Single Crystals

    SciTech Connect

    Yang, G.; Bolotnikov, A; Cui, Y; Camarda, G; Hossain, A; James, R

    2009-01-01

    The local impurity distribution in Te inclusions of CdZnTe (CZT) crystal was investigated by the time-of-flight secondary ion mass spectrometry (Tof-SIMS) technique. Direct evidence of impurity gettering in Te inclusions has been observed for the first time. The impurity gettering in Te inclusions originated from the diffusion mechanism during crystal growth and segregation mechanism during crystal cooling. This phenomenon is meaningful, because it reveals how Te inclusions affect CZT properties and provides a possible approach to reduce the impurities in CZT by the way of removing Te inclusions.

  20. Impurity-induced conductance anomaly in zigzag carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chang, Po-Yao; Huang, Wen-Min; Lin, Hsiu-Hau

    2009-02-01

    Impurities in carbon nanotubes give rise to rich physics due to the honeycomb lattice structure. We concentrate on the conductance through a point-like defect in metallic zigzag carbon nanotube via the Landauer-Büttiker approach. At low bias, the conductance is suppressed due to the presence of an additional impurity state existing only on one of the sublattices. In consequence, the suppression is exactly half of the perfect conductance without impurity. Furthermore, there exists a transport resonance at larger bias where the perfect conductance is recovered as if the impurity were absent. Implications of these conductance anomalies are elaborated and experimental detections in realistic carbon nanotubes are also discussed.

  1. 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.

  2. Studies of impurity behavior in TFTR

    SciTech Connect

    Hill, K.W.; Bitter, M.; Bretz, N.L.; Diesso, M.; Efthimion, P.C.; Von Goeler, S.; Kiraly, J.; Ramsey, A.T.; Sauthoff, N.R.; Schivell, J.

    1986-03-01

    Central medium- and low-Z impurity concentrations and Z/sub eff/ have been measured by x-ray spectrometry in Tokamak Fusion Test Reactor discharges during three periods of operation. These were the (1) start-up period, (2) ohmic heating, and (3) ohmic heating portion of the two neutral beam periods, distinguished mainly by different vacuum vessel internal hardware and increasing plasma current and toroidal field capability. Plasma parameters spanned minor radius a = 0.41 - 0.83 m, major radius R = 2.1 - 3.1 m, current I/sub p = 0.25 - 2.0 MA, line-averaged electron density n-bar/sub e/ = 0.9 - 4.0 x 10/sup 19/ m/sup -3/, and toroidal magnetic field B/sub T/ = 1.8 - 4.0 T. The metal impurities came mostly from the limiter. At low densities titanium or nickel approached 1% of n/sub e/ during operation on a TiC-coated graphite or Inconel limiter, respectively. Lower levels of Cr, Fe, and Ni (less than or equal to0.1%) were observed with a graphite limiter at similarly low densities; these elements were removed mainly from stainless steel or Inconel hardware within the vacuum vessel during pulse discharge cleaning or plasma operation on an Inconel limiter and then deposited on the graphite limiter. Hardware closest to the graphite limiter contributed most to the deposits.

  3. 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.

  4. Particle fueling and impurity control in PDX

    NASA Astrophysics Data System (ADS)

    Fonck, R. J.; Bell, M.; Bol, K.; Budny, R.; Couture, P.; Darrow, D.; Dylla, H.; Goldston, R.; Grek, B.; Hawryluk, R.; Ida, K.; Jaehnig, K.; Johnson, D.; Kaita, R.; Kaye, S.; Kugel, H.; Leblanc, B.; Mansfield, D.; Mcbride, T.; Mcguire, K.; Milora, S.; Mueller, D.; Okabayashi, M.; Owens, D.; Post, D.; Reusch, M.; Schmidt, G.; Sesnic, S.; Takahashi, H.; Tenney, F.; Ulrickson, M.

    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 alternative 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 30-40% of the total input power is radiated while ~15% is absorbed by the limiting surface, except in the open divertor case, where 60% flows to the neutralizer plate. In all operating configurations, Zeff usually rises at the onset of neutral beam injection. Both open divertor pl;asmas and those formed on a well conditioned water-cooled limiter have Zeff ⪅ 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.

  5. Examining the Relational Processes of a Highly Successful Teacher of African American Children

    ERIC Educational Resources Information Center

    Cholewa, Blaire; Amatea, Ellen; West-Olatunji, Cirecie A.; Wright, Ashley

    2012-01-01

    Culturally responsive educational practices have arisen as effective means of increasing culturally diverse students' academic achievement and psychological well-being; however, the relational processes involved are not well understood. Using grounded theory, this study examines the relational processes of one culturally responsive teacher and her…

  6. RKKY interaction of magnetic impurities in Dirac and Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Chang, Hao-Ran; Zhou, Jianhui; Wang, Shi-Xiong; Shan, Wen-Yu; Xiao, Di

    2015-12-01

    We theoretically study the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between magnetic impurities in both Dirac and Weyl semimetals (SMs). We find that the internode process, as well as the unique three-dimensional spin-momentum locking, has significant influences on the RKKY interaction, resulting in both a Heisenberg and an Ising term, and an additional Dzyaloshinsky-Moriya term if the inversion symmetry is absent. These interactions can lead to rich spin textures and possible ferromagnetism in Dirac and time-reversal symmetry-invariant Weyl SMs. The effect of anisotropic Dirac and Weyl nodes on the RKKY interaction is also discussed. Our results provide an alternative scheme to engineer topological SMs and shed new light on the application of Dirac and Weyl SMs in spintronics.

  7. Effects of impurities on silicon solar-cell performance

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.

    1986-01-01

    Model analyses indicate that sophisticated solar cell designs (back surface fields, optical reflectors, surface passivation, and double layer antireflective coatings) can produce devices with conversion efficiencies above 20%. To realize this potential, the quality of the silicon from which the cells are made must be improved; and these excellent electrical properties must be maintained during device processing. As the cell efficiency rises, the sensitivity to trace contaminants also increases. For example, the threshold Ti impurity concentraion at which cell performance degrades is more than an order of magnitude lower for an 18% cell than for a 16% cell. Similar behavior occurs for numerous other metal species which introduce deep level traps that stimulate the recombination of photogenerated carriers in silicon. Purification via crystal growth in conjunction with gettering steps to preserve the large diffusion length of the as grown material can lead to the production of devices with efficiencies above 18%, as verified experimentally.

  8. 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

  9. Core disgust and moral disgust are related to distinct spatiotemporal patterns of neural processing: an event-related potential study.

    PubMed

    Luo, Yu; Shen, Weilin; Zhang, Yu; Feng, Ting-yong; Huang, Hao; Li, Hong

    2013-10-01

    Core disgust is thought to rely more on sensory and perceptual processes, whereas moral disgust is thought to rely more on social evaluation processes. However, little is known about the neurocognitive mechanisms underlying these two types of disgust. We recorded event-related potentials (ERPs) from participants while they performed a lexical decision task in which core- and moral-disgust words were intermixed with neutral words and pseudowords. Lexical judgment was faster for coredisgust words and slower for moral-disgust words, relative to the neutral words. Core-disgust words, relative to neutral words, elicited a larger early posterior negative (EPN), a larger N320, a smaller N400, and a larger late positive component (LPC), whereas moral disgust words elicited a smaller N320 and a larger N400 than neutral words. These results suggest that the N320 and N400 components are particularly sensitive to the neurocognitive processes that overlap in processing both core and moral disgust, whereas the EPN and LPC may reflect process that are particularly sensitive to core disgust.

  10. 7 CFR 58.738 - Pasteurized process cheese spread and related products.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Pasteurized process cheese spread and related products... and Grading Service 1 Quality Specifications for Finished Products § 58.738 Pasteurized process cheese... of Identity for Pasteurized Process Cheese Spreads, Food and Drug Administration. The pH...

  11. 7 CFR 58.738 - Pasteurized process cheese spread and related products.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Pasteurized process cheese spread and related products... and Grading Service 1 Quality Specifications for Finished Products § 58.738 Pasteurized process cheese... of Identity for Pasteurized Process Cheese Spreads, Food and Drug Administration. The pH...

  12. 7 CFR 58.738 - Pasteurized process cheese spread and related products.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Pasteurized process cheese spread and related products... and Grading Service 1 Quality Specifications for Finished Products § 58.738 Pasteurized process cheese... of Identity for Pasteurized Process Cheese Spreads, Food and Drug Administration. The pH...

  13. 7 CFR 58.738 - Pasteurized process cheese spread and related products.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Pasteurized process cheese spread and related products... and Grading Service 1 Quality Specifications for Finished Products § 58.738 Pasteurized process cheese... of Identity for Pasteurized Process Cheese Spreads, Food and Drug Administration. The pH...

  14. 7 CFR 58.738 - Pasteurized process cheese spread and related products.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Pasteurized process cheese spread and related products... and Grading Service 1 Quality Specifications for Finished Products § 58.738 Pasteurized process cheese... of Identity for Pasteurized Process Cheese Spreads, Food and Drug Administration. The pH...

  15. Relative Saliency in Change Signals Affects Perceptual Comparison and Decision Processes in Change Detection

    ERIC Educational Resources Information Center

    Yang, Cheng-Ta

    2011-01-01

    Change detection requires perceptual comparison and decision processes on different features of multiattribute objects. How relative salience between two feature-changes influences the processes has not been addressed. This study used the systems factorial technology to investigate the processes when detecting changes in a Gabor patch with visual…

  16. Josephson junction on one edge of a two dimensional topological insulator affected by magnetic impurity.

    PubMed

    Zhang, Shu-Feng; Zhu, Wei; Sun, Qing-Feng

    2013-07-24

    The current-phase relation in a Josephson junction formed by putting two s-wave superconductors on the same edge of a two dimensional topological insulator is investigated. We consider the case in which the junction length is finite and magnetic impurity exists. The similarities and differences with respect to a conventional Josephson junction are discussed. Both the 2π- and 4π-period current-phase relations (I2π(ϕ),I4π(ϕ)) are studied. There is a sharp jump at ϕ = π and ϕ = 2π for I2π and I4π, respectively, in the clean junction. For I2π, the sharp jump is robust against the impurity strength and distribution. However, for I4π, an impurity makes the jump at ϕ = 2π smooth. The critical (maximum) current Ic,2π of I2π is given and we find it will be increased by an asymmetrical distribution of the impurity.

  17. Face Processing in Infancy: Developmental Changes in the Use of Different Kinds of Relational Information

    ERIC Educational Resources Information Center

    Bhatt, Ramesh S.; Bertin, Evelin; Hayden, Angela; Reed, Andrea

    2005-01-01

    Adults use both first-order, or categorical, relations among features (e.g., the nose is above the mouth), and second-order, or fine spatial relations (e.g., the space between eyes), to process faces. Adults' expertise in face processing is thought to be based on the use of second-order relations. In the current study, 5-month-olds detected…

  18. Working Memory, Animacy, and Verb Class in the Processing of Relative Clauses

    ERIC Educational Resources Information Center

    Traxler, M.J.; Williams, R.S.; Blozis, S.A.; Morris, R.K.

    2005-01-01

    In three eye-movement monitoring experiments, participants' working memory capacity was assessed and they read sentences containing subject-extracted and object-extracted relative clauses. In Experiment 1, sentences lacked helpful semantic cues, object-relatives were harder to process than subject relatives, and working memory capacity did not…

  19. An ERP Study of the Processing of Subject and Object Relative Clauses in Japanese

    ERIC Educational Resources Information Center

    Ueno, Mieko; Garnsey, Susan M.

    2008-01-01

    Using reading times and event-related brain potentials (ERPs), we investigated the processing of Japanese subject and object relative clauses (SRs/ORs). Previous research on English relative clauses shows that ORs take longer to read (King & Just, 1991) and elicit anterior negativity between fillers and gaps (King & Kutas, 1995), which is…

  20. Sentence Integration Processes: An ERP Study of Chinese Sentence Comprehension with Relative Clauses

    ERIC Educational Resources Information Center

    Yang, Chin Lung; Perfetti, Charles A.; Liu, Ying

    2010-01-01

    In an event-related potentials (ERPs) study, we examined the comprehension of different types of Chinese (Mandarin) relative clauses (object vs. subject-extracted) to test the universality and language specificity of sentence comprehension processes. Because Chinese lacks morphosyntactic cues to sentence constituent relations, it allows a test of…

  1. The Relevance of the Social Information Processing Model for Understanding Relational Aggression in Girls

    ERIC Educational Resources Information Center

    Crain, Marcelle M.; Finch, Cambra L.; Foster, Sharon L.

    2005-01-01

    Two studies examined whether social information-processing variables predict relational aggression in girls. In Study 1, fourth- through sixth-grade girls reported their intent attributions, social goals, outcome expectancies for relational aggression, and the likelihood that they would choose a relationally aggressive response in response to…

  2. Carbon isotope ratios and impurities in diamonds from Southern Africa

    NASA Astrophysics Data System (ADS)

    Kidane, Abiel; Koch-Müller, Monika; Morales, Luiz; Wiedenbeck, Michael; De Wit, Maarten

    2015-04-01

    yield a constant 13C/12C ratio with RSD of better than 0.5 ‰ . Using the natural diamond as calibratrant, a preliminary result on a selected diamond from the four kimberlitic sample suites yields a δ13C in range between -3 to -7 ‰ . Reference: Howell, D., O'Neill, C. J., Grant, K. J., Griffin, W. L., Pearson, N. J., & O'Reilly, S. Y. (2012). μ-FTIR mapping: Distribution of impurities in different types of diamond growth. Diamond and Related Materials, 29, 29-36. doi:10.1016/j.diamond.2012.06.003.

  3. Activation of the human sensorimotor cortex during error-related processing: a magnetoencephalography study.

    PubMed

    Stemmer, Brigitte; Vihla, Minna; Salmelin, Riitta

    2004-05-13

    We studied error-related processing using magnetoencephalography (MEG). Previous event-related potential studies have documented error negativity or error-related negativity after incorrect responses, with a suggested source in the anterior cingulate cortex or supplementary motor area. We compared activation elicited by correct and incorrect trials using auditory and visual choice-reaction time tasks. Source areas showing different activation patterns in correct and error conditions were mainly located in sensorimotor areas, both ipsi- and contralateral to the response, suggesting that activation of sensorimotor circuits accompanies error processing. Additional activation at various other locations suggests a distributed network of brain regions active during error-related processing. Activation specific to incorrect trials tended to occur later in MEG than EEG data, possibly indicating that EEG and MEG detect different neural networks involved in error-related processes.

  4. Tight-Binding Description of Impurity States in Semiconductors

    ERIC Educational Resources Information Center

    Dominguez-Adame, F.

    2012-01-01

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

  5. 40 CFR 158.340 - Discussion of formation of impurities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... require an expanded discussion of information on impurities: (1) From other possible chemical reactions... why they may be present. The discussion should be based on established chemical theory and on what the... range of levels) of these impurities. (iii) The intended reactions and side reactions which may occur...

  6. Viscoelasticity of colloidal polycrystals doped with impurities

    NASA Astrophysics Data System (ADS)

    Louhichi, Ameur; Tamborini, Elisa; Oberdisse, Julian; Cipelletti, Luca; Ramos, Laurence

    2015-09-01

    We investigate how the microstructure of a colloidal polycrystal influences its linear visco-elasticity. We use thermosensitive copolymer micelles that arrange in water in a cubic crystalline lattice, yielding a colloidal polycrystal. The polycrystal is doped with a small amount of nanoparticles, of size comparable to that of the micelles, which behave as impurities and thus partially segregate in the grain boundaries. We show that the shear elastic modulus only depends on the packing of the micelles and varies neither with the presence of nanoparticles nor with the crystal microstructure. By contrast, we find that the loss modulus is strongly affected by the presence of nanoparticles. A comparison between rheology data and small-angle neutron-scattering data suggests that the loss modulus is dictated by the total amount of nanoparticles in the grain boundaries, which in turn depends on the sample microstructure.

  7. Viscoelasticity of colloidal polycrystals doped with impurities.

    PubMed

    Louhichi, Ameur; Tamborini, Elisa; Oberdisse, Julian; Cipelletti, Luca; Ramos, Laurence

    2015-09-01

    We investigate how the microstructure of a colloidal polycrystal influences its linear visco-elasticity. We use thermosensitive copolymer micelles that arrange in water in a cubic crystalline lattice, yielding a colloidal polycrystal. The polycrystal is doped with a small amount of nanoparticles, of size comparable to that of the micelles, which behave as impurities and thus partially segregate in the grain boundaries. We show that the shear elastic modulus only depends on the packing of the micelles and varies neither with the presence of nanoparticles nor with the crystal microstructure. By contrast, we find that the loss modulus is strongly affected by the presence of nanoparticles. A comparison between rheology data and small-angle neutron-scattering data suggests that the loss modulus is dictated by the total amount of nanoparticles in the grain boundaries, which in turn depends on the sample microstructure. PMID:26465473

  8. The Mg impurity in nitride alloys

    SciTech Connect

    Zvanut, M. E.; Willoughby, W. R.; Sunay, U. R.; Koleske, D. D.; Allerman, A. A.; Wang, Ke; Araki, Tsutomu; Nanishi, Yasushi

    2014-02-21

    Although several magnetic resonance studies address the Mg acceptor in GaN, there are few reports on Mg doping in the alloys, where hole production depends strongly on the Al or In content. Our electron paramagnetic resonance (EPR) measurements of the p-type alloys suggest that the Mg impurity retains the axial symmetry, characteristic of a p-type dopant in both alloys; however, In and Al produce additional, different characteristics of the acceptor. In InGaN, the behavior is consistent with a lowering of the acceptor level and increasing hole density as In concentration increases. For AlGaN, the amount of neutral Mg decreases with increasing Al content, which is attributed to different kinetics of hydrogen diffusion thought to occur in samples with higher Al mole fraction.

  9. Surface impurity removal from DIII-D graphite tiles by boron carbide grit blasting

    SciTech Connect

    Lee, R.L.; Hollerbach, M.A.; Holtrop, K.L.; Kellman, A.G.; Taylor, P.L.; West, W.P.

    1993-11-01

    During the latter half of 1992, the DIII-D tokamak at General Atomics (GA) underwent several modifications of its interior. One of the major tasks involved the removal of accumulated metallic impurities from the surface of the graphite tiles used to line the plasma facing surfaces inside of the tokamak. Approximately 1500 graphite tiles and 100 boron nitride tiles from the tokamak were cleaned to remove the metallic impurities. The cleaning process consisted of several steps: the removed graphite tiles were permanently marked, surface blasted using boron carbide (B{sub 4}C) grit media (approximately 37 {mu}m. diam.), ultrasonically cleaned in ethanol to remove loose dust, and outgassed at 1000{degrees}C. Tests were done using, graphite samples and different grit blaster settings to determine the optimum propellant and abrasive media pressures to remove a graphite layer approximately 40-50 {mu}m deep and yet produce a reasonably smooth finish. EDX measurements revealed that the blasting technique reduced the surface Ni, Cr, and Fe impurity levels to those of virgin graphite. In addition to the surface impurity removal, tritium monitoring was performed throughout the cleaning process. A bubbler system was set up to monitor the tritium level in the exhaust gas from the grit blaster unit. Surface wipes were also performed on over 10% of the tiles. Typical surface tritium concentrations of the tiles were reduced from about 500 dpm/100 cm{sup 2} to less than 80 dpm/100 cm{sup 2} following the cleaning. This tile conditioning, and the installation of additional graphite tiles to cover a high fraction of the metallic plasma facing surfaces, has substantially reduced metallic impurities in the plasma discharges which has allowed rapid recovery from a seven-month machine opening and regimes of enhanced plasma energy confinement to be more readily obtained. Safety issues concerning blaster operator exposure to carcinogenic metals and radioactive tritium will also be addressed.

  10. Tuning oxygen impurities and microstructure of nanocrystalline silicon photovoltaic materials through hydrogen dilution

    PubMed Central

    2014-01-01

    As a great promising material for third-generation thin-film photovoltaic cells, hydrogenated nanocrystalline silicon (nc-Si:H) thin films have a complex mixed-phase structure, which determines its defectful nature and easy residing of oxygen impurities. We have performed a detailed investigation on the microstructure properties and oxygen impurities in the nc-Si:H thin films prepared under different hydrogen dilution ratio treatment by the plasma-enhanced chemical vapor deposition (PECVD) process. X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and optical transmission spectroscopy have been utilized to fully characterize the microstructure properties of the nc-Si:H films. The oxygen and hydrogen contents have been obtained from infrared absorption spectroscopy. And the configuration state of oxygen impurities on the surface of the films has been confirmed by X-ray photoelectron spectroscopy, indicating that the films were well oxidized in the form of SiO2. The correlation between the hydrogen content and the volume fraction of grain boundaries derived from the Raman measurements shows that the majority of the incorporated hydrogen is localized inside the grain boundaries. Furthermore, with the detailed information on the bonding configurations acquired from the infrared absorption spectroscopy, a full explanation has been provided for the mechanism of the varying microstructure evolution and oxygen impurities based on the two models of ion bombardment effect and hydrogen-induced annealing effect. PMID:24994958

  11. Confirming Impurity Effect in Silver-Point Realization from Cell-to-Cell Comparisons

    NASA Astrophysics Data System (ADS)

    Widiatmo, J. V.; Harada, K.; Yamazawa, K.; Tamba, J.; Arai, M.

    2011-12-01

    As a continuation to earlier work on the silver-point realization, already reported at TEMPMEKO 2007, a new silver-point cell has been fabricated using 6N-nominal grade material that was analyzed by means of glow discharge mass spectrometry (GDMS) by the manufacturer. This new cell is evaluated by a direct cell comparison with one of the existing cells, which was also already reported at TEMPMEKO 2007. One of those existing cells was drawn out from its crucible, and its ingot was analyzed by GDMS at four positions, namely, at around the center of the top, of the middle, of the bottom, and around the outer part of middle areas for the purpose of confirming whether or not there has been differences in the content of impurities before and after the cell fabrication, as well as differences in impurity homogeneity within the ingot. As results of the aforementioned measurements, it was found that the homogeneity of impurities in the silver ingot was on average within 50 %. It was also found that cell-to-cell temperature differences change along with the progressing solidification process. As a consequence, it was concluded that, for an accurate cell-to-cell comparison, the location in the freezing plateau, where the comparison is done, should be determined. Also obtained here is that the slope analysis was consistent with both the cell-to-cell comparison and the impurity analysis.

  12. Empirical correlations between the arrhenius' parameters of impurities' diffusion coefficients in CdTe crystals

    DOE PAGES

    Shcherbak, L.; Kopach, O.; Fochuk, P.; James, R. B.; Bolotnikov, A. E.

    2015-01-21

    Understanding of self- and dopant-diffusion in semiconductor devices is essential to our being able to assure the formation of well-defined doped regions. In this paper, we compare obtained in the literature up to date the Arrhenius’ parameters (D=D0exp(–ΔEa/kT)) of point-defect diffusion coefficients and the I-VII groups impurities in CdTe crystals and films. We found that in the diffusion process there was a linear dependence between the pre-exponential factor, D0, and the activation energy, ΔEa, of different species: This was evident in the self-diffusivity and isovalent impurity Hg diffusivity as well as for the dominant IIIA and IVA groups impurities andmore » Chlorine, except for the fast diffusing elements (e.g., Cu and Ag), chalcogens O, S, and Se, halogens I and Br as well as the transit impurities Mn, Co, Fe. As a result, reasons of the lack of correspondence of the data to compensative dependence are discussed.« less

  13. Empirical correlations between the arrhenius' parameters of impurities' diffusion coefficients in CdTe crystals

    SciTech Connect

    Shcherbak, L.; Kopach, O.; Fochuk, P.; James, R. B.; Bolotnikov, A. E.

    2015-01-21

    Understanding of self- and dopant-diffusion in semiconductor devices is essential to our being able to assure the formation of well-defined doped regions. In this paper, we compare obtained in the literature up to date the Arrhenius’ parameters (D=D0exp(–ΔEa/kT)) of point-defect diffusion coefficients and the I-VII groups impurities in CdTe crystals and films. We found that in the diffusion process there was a linear dependence between the pre-exponential factor, D0, and the activation energy, ΔEa, of different species: This was evident in the self-diffusivity and isovalent impurity Hg diffusivity as well as for the dominant IIIA and IVA groups impurities and Chlorine, except for the fast diffusing elements (e.g., Cu and Ag), chalcogens O, S, and Se, halogens I and Br as well as the transit impurities Mn, Co, Fe. As a result, reasons of the lack of correspondence of the data to compensative dependence are discussed.

  14. Classification of illicit heroin by UPLC-Q-TOF analysis of acidic and neutral manufacturing impurities.

    PubMed

    Liu, Cuimei; Hua, Zhendong; Bai, Yanping

    2015-12-01

    The illicit manufacture of heroin results in the formation of trace levels of acidic and neutral manufacturing impurities that provide valuable information about the manufacturing process used. In this work, a new ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF) method; that features high resolution, mass accuracy and sensitivity for profiling neutral and acidic heroin manufacturing impurities was developed. After the UPLC-Q-TOF analysis, the retention times and m/z data pairs of acidic and neutral manufacturing impurities were detected, and 19 peaks were found to be evidently different between heroin samples from "Golden Triangle" and "Golden Crescent". Based on the data set of these 19 impurities in 150 authentic heroin samples, classification of heroin geographic origins was successfully achieved utilizing partial least squares discriminant analysis (PLS-DA). By analyzing another data set of 267 authentic heroin samples, the developed discrimiant model was validated and proved to be accurate and reliable. PMID:26364155

  15. Effects of surface-active impurities on the liquid bridge dynamics

    NASA Astrophysics Data System (ADS)

    Ponce-Torres, A.; Vega, E. J.; Montanero, J. M.

    2016-05-01

    We examine experimentally the effects of surface-active impurities on the small-amplitude free oscillations of axisymmetric liquid bridges. The surface tension, oscillation frequency, and damping rate are measured at different instants from the free surface formation. The experiments with n-hexadecane and n-dodecane show that none of these interfacial quantities is significantly affected by the free surface age. The damping rates exceed by a O(1) quantity their corresponding values for a clean free surface. This extra-damping can be modeled in terms of the monolayer shear viscosity exclusively. Similar values of this quantity are obtained for n-hexadecane and n-dodecane, although the impurity effects on the surface tension are much greater in the first case. We conducted experiments with deionized water liquid bridges to analyze the impurity effects on free surfaces with high elasticity numbers, where Marangoni convection is expected to increase the monolayer dissipation. In this case, the damping rates are up to three times as those of a clean free surface. The monolayer dissipative effects do not increase as the free surface ages, although the surface tension decreases considerably during this process. Similar impurity effects are observed when an anionic surfactant is dissolved in deionized water. For a fixed value of the liquid bridge slenderness, both the oscillation frequency and damping rate are functions of the liquid bridge volume exclusively, independently of the free surface age and the liquid-ambient combination. Extra-dissipation increases sharply as the liquid bridge volume decreases.

  16. Mesoscopic Impurities Expose a Nucleation-Limited Regime of Crystal Growth

    NASA Astrophysics Data System (ADS)

    Sleutel, Mike; Lutsko, James F.; Maes, Dominique; Van Driessche, Alexander E. S.

    2015-06-01

    Nanoscale self-assembly is naturally subject to impediments at the nanoscale. The recently developed ability to follow processes at the molecular level forces us to resolve older, coarse-grained concepts in terms of their molecular mechanisms. In this Letter, we highlight one such example. We present evidence based on experimental and simulation data that one of the cornerstones of crystal growth theory, the Cabrera-Vermilyea model of step advancement in the presence of impurities, is based on incomplete physics. We demonstrate that the piercing of an impurity fence by elementary steps is not solely determined by the Gibbs-Thomson effect, as assumed by Cabrera-Vermilyea. Our data show that for conditions leading up to growth cessation, step retardation is dominated by the formation of critically sized fluctuations. The growth recovery of steps is counter to what is typically assumed, not instantaneous. Our observations on mesoscopic impurities for lysozyme expose a nucleation-dominated regime of growth that has not been hitherto considered, where the system alternates between zero and near-pure velocity. The time spent by the system in arrest is the nucleation induction time required for the step to amass a supercritical fluctuation that pierces the impurity fence.

  17. Single atom impurity in a single molecular transistor

    SciTech Connect

    Ray, S. J.

    2014-10-21

    The influence of an impurity atom on the electrostatic behaviour of a Single Molecular Transistor was investigated through Ab-initio calculations in a double-gated geometry. The charge stability diagram carries unique signature of the position of the impurity atom in such devices which together with the charging energy of the molecule could be utilised as an electronic fingerprint for the detection of such impurity states in a nano-electronic device. The two gated geometry allows additional control over the electrostatics as can be seen from the total energy surfaces (for a specific charge state), which is sensitive to the positions of the impurity. These devices which are operational at room temperature can provide significant advantages over the conventional silicon based single dopant devices functional at low temperature. The present approach could be a very powerful tool for the detection and control of individual impurity atoms in a single molecular device and for applications in future molecular electronics.

  18. Impurity effect on surface states of Bi (111) ultrathin films

    NASA Astrophysics Data System (ADS)

    Zhu, Kai; Tian, Dai; Wu, Lin; Xu, Jianli; Jin, Xiaofeng

    2016-08-01

    The surface impurity effect on the surface-state conductivity and weak antilocalization (WAL) effect has been investigated in epitaxial Bi (111) films by magnetotransport measurements at low temperatures. The surface-state conductivity is significantly reduced by the surface impurities of Cu, Fe, and Co. The magnetotransport data demonstrate that the observed WAL is robust against deposition of nonmagnetic impurities, but it is quenched by the deposition of magnetic impurities which break the time reversal symmetry. Our results help to shed light on the effect of surface impurities on the electron and spin transport properties of a 2D surface electron systems. Project supported by the National Basic Research Program of China (Grants Nos. 2015CB921400 and 2011CB921802) and the National Natural Science Foundation of China (Grants Nos. 11374057, 11434003, and 11421404).

  19. 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.

  20. Impurity transport due to electromagnetic drift wave turbulence

    NASA Astrophysics Data System (ADS)

    Moradi, S.; Pusztai, I.; Mollén, A.; Fülöp, T.

    2012-03-01

    Finite β effects on impurity transport are studied through local linear gyrokinetic simulations with GYRO [J. Candy and E. Belli, General Atomics Report No. GA-A26818, 2011]; in particular, we investigate the parametric dependences of the impurity peaking factor (zero-flux density gradient) and the onset of the kinetic ballooning modes (KBMs). We find that electromagnetic effects even at low β can have significant impact on the impurity transport. The KBM instability threshold depends on the plasma parameters, particularly strongly on plasma shape. We have shown that magnetic geometry significantly influences the results, and the commonly used s-α model overestimates the KBM growth rates and ITG stabilization at high β. In the β range, where the KBM is the dominant instability the impurity peaking factor is strongly reduced, with very little dependence on β and the impurity charge.