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Sample records for ag rwe dea

  1. AMA- and RWE- Based Adaptive Kalman Filter for Denoising Fiber Optic Gyroscope Drift Signal

    PubMed Central

    Yang, Gongliu; Liu, Yuanyuan; Li, Ming; Song, Shunguang

    2015-01-01

    An improved double-factor adaptive Kalman filter called AMA-RWE-DFAKF is proposed to denoise fiber optic gyroscope (FOG) drift signal in both static and dynamic conditions. The first factor is Kalman gain updated by random weighting estimation (RWE) of the covariance matrix of innovation sequence at any time to ensure the lowest noise level of output, but the inertia of KF response increases in dynamic condition. To decrease the inertia, the second factor is the covariance matrix of predicted state vector adjusted by RWE only when discontinuities are detected by adaptive moving average (AMA).The AMA-RWE-DFAKF is applied for denoising FOG static and dynamic signals, its performance is compared with conventional KF (CKF), RWE-based adaptive KF with gain correction (RWE-AKFG), AMA- and RWE- based dual mode adaptive KF (AMA-RWE-DMAKF). Results of Allan variance on static signal and root mean square error (RMSE) on dynamic signal show that this proposed algorithm outperforms all the considered methods in denoising FOG signal. PMID:26512665

  2. AMA- and RWE- Based Adaptive Kalman Filter for Denoising Fiber Optic Gyroscope Drift Signal.

    PubMed

    Yang, Gongliu; Liu, Yuanyuan; Li, Ming; Song, Shunguang

    2015-10-23

    An improved double-factor adaptive Kalman filter called AMA-RWE-DFAKF is proposed to denoise fiber optic gyroscope (FOG) drift signal in both static and dynamic conditions. The first factor is Kalman gain updated by random weighting estimation (RWE) of the covariance matrix of innovation sequence at any time to ensure the lowest noise level of output, but the inertia of KF response increases in dynamic condition. To decrease the inertia, the second factor is the covariance matrix of predicted state vector adjusted by RWE only when discontinuities are detected by adaptive moving average (AMA).The AMA-RWE-DFAKF is applied for denoising FOG static and dynamic signals, its performance is compared with conventional KF (CKF), RWE-based adaptive KF with gain correction (RWE-AKFG), AMA- and RWE- based dual mode adaptive KF (AMA-RWE-DMAKF). Results of Allan variance on static signal and root mean square error (RMSE) on dynamic signal show that this proposed algorithm outperforms all the considered methods in denoising FOG signal.

  3. DEA degradation mechanism

    SciTech Connect

    Meisen, A.; Kennard, M.L.

    1982-10-01

    Examines factors that increase diethanolamine (DEA) degradation, which reportedly depends on temperature, pressure, gas composition, amine concentration, pH of the amine solution and the presence of metal ions. Plant operators have tried to solve the problem by changing operating conditions and/or installing activated carbon filters. DEA degradation is frequently experienced in gas plants used for removing acidic gases such as carbon dioxide and hydrogen sulfide from light hydrocarbons. Experimental results reveal that degradation is governed by: solubility of CO/sub 2/ in the DEA solution; degree of dissociation of the DEA molecules in solution; interaction of DEA and CO/sub 2/ molecules and/or ionic complexes. Most, or all, these phenomena are affected by temperature, pressure, DEA concentration and pH. A series of tests to determine whether activated carbon is capable of removing impurities from partially degraded DEA solutions showed that this treatment did not remove any major degradation compounds from the solutions.

  4. EMS & the DEA.

    PubMed

    Beeson, Jeff; Ayres, Chris

    2010-01-01

    It's clear that EMS medical directors and management staff must be vigilant in their oversight of implementation, administration and monitoring of controlled substances within their agencies to best serve the public and avoid running afoul of investigation and incurring significant penalties. Those potentially affected by the need for individual registrations of both emergency vehicles and central inventory systems should carefully monitor upcoming developments in the interpretation od DEA regulations.

  5. DEA Multimedia Drug Library: Marijuana

    MedlinePlus

    ... DEA Press Room » Multi-Media Library » Image Gallery » Marijuana MARIJUANA To Save Images: First click on the thumbnail ... Save in directory and then click Save. Indoor Marijuana Grow Indoor Marijuana Grow Loose Marijuana Marinol 10mg ...

  6. Biomimetic control for DEA arrays

    NASA Astrophysics Data System (ADS)

    O'Brien, Benjamin; Gisby, Todd; Xie, Sheng Q.; Calius, Emilio; Anderson, Iain

    2010-04-01

    Arrays of actuators are ubiquitous in nature for manipulation, pumping and propulsion. Often these arrays are coordinated in a multi-level fashion with distributed sensing and feedback manipulated by higher level controllers. In this paper we present a biologically inspired multi-level control strategy and apply it to control an array of Dielectric Elastomer Actuators (DEA). A test array was designed consisting of three DEA arranged to tilt a set of rails on which a ball rolls. At the local level the DEA were controlled using capacitive self-sensing state machines that switched the actuator off and on when capacitive thresholds were exceeded, resulting in the steady rolling of the ball around the rails. By varying the voltage of the actuators in the on state, it was possible to control the speed of the ball to match a set point. A simple integral derivative controller was used to do this and an observer law was formulated to track the speed of the ball. The array demonstrated the ability to self start, roll the ball in either direction, and run at a range of speeds determined by the maximum applied voltage. The integral derivative controller successfully tracked a square wave set point. Whilst the test application could have been controlled with a classic centralised controller, the real benefit of the multi-level strategy becomes apparent when applied to larger arrays and biomimetic applications that are ideal for DEA. Three such applications are discussed; a robotic heart, a peristaltic pump and a ctenophore inspired propulsion array.

  7. 21 CFR 1305.17 - Preservation of DEA Forms 222.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Preservation of DEA Forms 222. 1305.17 Section 1305.17 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE ORDERS FOR SCHEDULE I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.17 Preservation of DEA Forms 222. (a) The purchaser...

  8. 21 CFR 1305.17 - Preservation of DEA Forms 222.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Preservation of DEA Forms 222. 1305.17 Section 1305.17 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE ORDERS FOR SCHEDULE I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.17 Preservation of DEA Forms 222. (a) The purchaser...

  9. 21 CFR 1305.17 - Preservation of DEA Forms 222.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Preservation of DEA Forms 222. 1305.17 Section 1305.17 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE ORDERS FOR SCHEDULE I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.17 Preservation of DEA Forms 222. (a) The purchaser...

  10. 21 CFR 1305.17 - Preservation of DEA Forms 222.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Preservation of DEA Forms 222. 1305.17 Section 1305.17 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE ORDERS FOR SCHEDULE I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.17 Preservation of DEA Forms 222. (a) The purchaser...

  11. 21 CFR 1305.17 - Preservation of DEA Forms 222.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Preservation of DEA Forms 222. 1305.17 Section 1305.17 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE ORDERS FOR SCHEDULE I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.17 Preservation of DEA Forms 222. (a) The purchaser...

  12. Evaluation of Digital Libraries: A DEA Approach.

    ERIC Educational Resources Information Center

    Shim, Wonsik; Kantor, Paul B.

    1999-01-01

    A complex tool, data envelopment analysis (DEA) was used to evaluate the relative efficiency of major academic research libraries that are members of the Association of Research Libraries (ARL). Results of a two-year base line study using traditional measures taken from 1995-96 ARL statistics are reported. (AEF)

  13. DEA Multi-Media Drug Library

    MedlinePlus

    ... Marijuana Use Among Youth & Young Adults (2017) Diversion Publications FEATURED VIDEOS DEA Fentanyl Roll Call Video Chasing the Dragon: The Life of an Opiate Addict Prescription Drug Abuse: Keeping Your Family Safe Text Messaging: Lost in Translation? Explore the Resources on Get Smart About Drugs ...

  14. 21 CFR 1305.11 - Procedure for obtaining DEA Forms 222.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Procedure for obtaining DEA Forms 222. 1305.11... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.11 Procedure for obtaining DEA Forms 222. (a) DEA..., which is based on the business activity of the registrant, will be imposed on the number of DEA...

  15. 21 CFR 1305.11 - Procedure for obtaining DEA Forms 222.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Procedure for obtaining DEA Forms 222. 1305.11... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.11 Procedure for obtaining DEA Forms 222. (a) DEA..., which is based on the business activity of the registrant, will be imposed on the number of DEA...

  16. 21 CFR 1305.11 - Procedure for obtaining DEA Forms 222.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Procedure for obtaining DEA Forms 222. 1305.11... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.11 Procedure for obtaining DEA Forms 222. (a) DEA..., which is based on the business activity of the registrant, will be imposed on the number of DEA...

  17. 21 CFR 1305.11 - Procedure for obtaining DEA Forms 222.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Procedure for obtaining DEA Forms 222. 1305.11... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.11 Procedure for obtaining DEA Forms 222. (a) DEA..., which is based on the business activity of the registrant, will be imposed on the number of DEA...

  18. 21 CFR 1305.11 - Procedure for obtaining DEA Forms 222.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Procedure for obtaining DEA Forms 222. 1305.11... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.11 Procedure for obtaining DEA Forms 222. (a) DEA..., which is based on the business activity of the registrant, will be imposed on the number of DEA...

  19. Degradation of aqueous DEA solutions in heat transfer tubes

    SciTech Connect

    Meisen, A.; Chakma, A.

    1985-01-01

    Experiments were performed on the degradation of aqueous diethanolamine (DEA) solutions passing through a coiled heat transfer tube (2.0032 mm ID, 3.175 mm OD, 4.8 m long) immersed in a constant temperature bath. The operating conditions were: DEA flow rate 0.011 to 0.0172 L/s, DEA concentration 20 to 40 wt%, DEA temperature 60 to 200/sup 0/C, CO/sub 2/ partial pressure 1.38 to 4.18 MPa. The degradation rate was found to increase with temperature, DEA concentration and CO/sub 2/ partial pressure; it decreased with solution flow rate. The degradation was accompanied by the formation of a fouling deposit. A simple mathematical model is presented for predicting DEA degradation.

  20. Ranking efficient DMUs using minimizing distance in DEA

    NASA Astrophysics Data System (ADS)

    Ziari, Shokrollah; Raissi, Sadigh

    2016-01-01

    In many applications, ranking of decision making units (DMUs) is a problematic technical task procedure to decision makers in data envelopment analysis (DEA), especially when there are extremely efficient DMUs. In such cases, many DEA models may usually get the same efficiency score for different DMUs. Hence, there is a growing interest in ranking techniques yet. The main purpose of this paper is to overcome the lack of infeasibility and unboundedness in some DEA ranking methods. The proposed method is for ranking extreme efficient DMUs in DEA based on exploiting the leave-one out and minimizing distance between DMU under evaluation and virtual DMU.

  1. Applying DEA Technique to Library Evaluation in Academic Research Libraries.

    ERIC Educational Resources Information Center

    Shim, Wonsik

    2003-01-01

    This study applied an analytical technique called Data Envelopment Analysis (DEA) to calculate the relative technical efficiency of 95 academic research libraries, all members of the Association of Research Libraries. DEA, with the proper model of library inputs and outputs, can reveal best practices in the peer groups, as well as the technical…

  2. 21 CFR 1305.29 - Reporting to DEA.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Reporting to DEA. 1305.29 Section 1305.29 Food and... SUBSTANCES Electronic Orders § 1305.29 Reporting to DEA. A supplier must, for each electronic order filled, forward either a copy of the electronic order or an electronic report of the order in a format that...

  3. 21 CFR 1305.29 - Reporting to DEA.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Reporting to DEA. 1305.29 Section 1305.29 Food and... SUBSTANCES Electronic Orders § 1305.29 Reporting to DEA. A supplier must, for each electronic order filled, forward either a copy of the electronic order or an electronic report of the order in a format that...

  4. 21 CFR 1305.29 - Reporting to DEA.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Reporting to DEA. 1305.29 Section 1305.29 Food and... SUBSTANCES Electronic Orders § 1305.29 Reporting to DEA. A supplier must, for each electronic order filled, forward either a copy of the electronic order or an electronic report of the order in a format that...

  5. 21 CFR 1305.29 - Reporting to DEA.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Reporting to DEA. 1305.29 Section 1305.29 Food and... SUBSTANCES Electronic Orders § 1305.29 Reporting to DEA. A supplier must, for each electronic order filled, forward either a copy of the electronic order or an electronic report of the order in a format that...

  6. 21 CFR 1305.29 - Reporting to DEA.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Reporting to DEA. 1305.29 Section 1305.29 Food and... SUBSTANCES Electronic Orders § 1305.29 Reporting to DEA. A supplier must, for each electronic order filled, forward either a copy of the electronic order or an electronic report of the order in a format that...

  7. 21 CFR 1305.12 - Procedure for executing DEA Forms 222.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Procedure for executing DEA Forms 222. 1305.12... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.12 Procedure for executing DEA Forms 222. (a) A purchaser must prepare and execute a DEA Form 222 simultaneously in triplicate by means of...

  8. 21 CFR 1305.19 - Cancellation and voiding of DEA Forms 222.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Cancellation and voiding of DEA Forms 222. 1305.19... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.19 Cancellation and voiding of DEA Forms 222. (a) A purchaser may cancel part or all of an order on a DEA Form 222 by notifying the supplier...

  9. 21 CFR 1305.16 - Lost and stolen DEA Forms 222.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Lost and stolen DEA Forms 222. 1305.16 Section... II CONTROLLED SUBSTANCES DEA Form 222 § 1305.16 Lost and stolen DEA Forms 222. (a) If a purchaser ascertains that an unfilled DEA Form 222 has been lost, he or she must execute another in triplicate...

  10. 21 CFR 1305.16 - Lost and stolen DEA Forms 222.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Lost and stolen DEA Forms 222. 1305.16 Section... II CONTROLLED SUBSTANCES DEA Form 222 § 1305.16 Lost and stolen DEA Forms 222. (a) If a purchaser ascertains that an unfilled DEA Form 222 has been lost, he or she must execute another in triplicate...

  11. 21 CFR 1305.18 - Return of unused DEA Forms 222.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Return of unused DEA Forms 222. 1305.18 Section... II CONTROLLED SUBSTANCES DEA Form 222 § 1305.18 Return of unused DEA Forms 222. If the registration... substances for which the purchaser is registered, the purchaser must return all unused DEA Forms 222 to...

  12. 21 CFR 1305.16 - Lost and stolen DEA Forms 222.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Lost and stolen DEA Forms 222. 1305.16 Section... II CONTROLLED SUBSTANCES DEA Form 222 § 1305.16 Lost and stolen DEA Forms 222. (a) If a purchaser ascertains that an unfilled DEA Form 222 has been lost, he or she must execute another in triplicate...

  13. 21 CFR 1305.16 - Lost and stolen DEA Forms 222.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Lost and stolen DEA Forms 222. 1305.16 Section... II CONTROLLED SUBSTANCES DEA Form 222 § 1305.16 Lost and stolen DEA Forms 222. (a) If a purchaser ascertains that an unfilled DEA Form 222 has been lost, he or she must execute another in triplicate...

  14. 21 CFR 1305.14 - Procedure for endorsing DEA Forms 222.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Procedure for endorsing DEA Forms 222. 1305.14... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.14 Procedure for endorsing DEA Forms 222. (a) A DEA Form 222, made out to any supplier who cannot fill all or a part of the order within the...

  15. 21 CFR 1305.19 - Cancellation and voiding of DEA Forms 222.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Cancellation and voiding of DEA Forms 222. 1305.19... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.19 Cancellation and voiding of DEA Forms 222. (a) A purchaser may cancel part or all of an order on a DEA Form 222 by notifying the supplier...

  16. 21 CFR 1305.18 - Return of unused DEA Forms 222.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Return of unused DEA Forms 222. 1305.18 Section... II CONTROLLED SUBSTANCES DEA Form 222 § 1305.18 Return of unused DEA Forms 222. If the registration... substances for which the purchaser is registered, the purchaser must return all unused DEA Forms 222 to...

  17. 21 CFR 1305.15 - Unaccepted and defective DEA Forms 222.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Unaccepted and defective DEA Forms 222. 1305.15... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.15 Unaccepted and defective DEA Forms 222. (a) A DEA Form 222 must not be filled if either of the following apply: (1) The order is not...

  18. 21 CFR 1305.14 - Procedure for endorsing DEA Forms 222.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Procedure for endorsing DEA Forms 222. 1305.14... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.14 Procedure for endorsing DEA Forms 222. (a) A DEA Form 222, made out to any supplier who cannot fill all or a part of the order within the...

  19. 21 CFR 1305.15 - Unaccepted and defective DEA Forms 222.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Unaccepted and defective DEA Forms 222. 1305.15... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.15 Unaccepted and defective DEA Forms 222. (a) A DEA Form 222 must not be filled if either of the following apply: (1) The order is not...

  20. 21 CFR 1305.13 - Procedure for filling DEA Forms 222.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Procedure for filling DEA Forms 222. 1305.13... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.13 Procedure for filling DEA Forms 222. (a) A purchaser must submit Copy 1 and Copy 2 of the DEA Form 222 to the supplier and retain Copy 3 in...

  1. 21 CFR 1305.13 - Procedure for filling DEA Forms 222.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Procedure for filling DEA Forms 222. 1305.13... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.13 Procedure for filling DEA Forms 222. (a) A purchaser must submit Copy 1 and Copy 2 of the DEA Form 222 to the supplier and retain Copy 3 in...

  2. 21 CFR 1305.12 - Procedure for executing DEA Forms 222.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Procedure for executing DEA Forms 222. 1305.12... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.12 Procedure for executing DEA Forms 222. (a) A purchaser must prepare and execute a DEA Form 222 simultaneously in triplicate by means of...

  3. 21 CFR 1305.18 - Return of unused DEA Forms 222.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Return of unused DEA Forms 222. 1305.18 Section... II CONTROLLED SUBSTANCES DEA Form 222 § 1305.18 Return of unused DEA Forms 222. If the registration... substances for which the purchaser is registered, the purchaser must return all unused DEA Forms 222 to...

  4. 21 CFR 1305.14 - Procedure for endorsing DEA Forms 222.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Procedure for endorsing DEA Forms 222. 1305.14... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.14 Procedure for endorsing DEA Forms 222. (a) A DEA Form 222, made out to any supplier who cannot fill all or a part of the order within the...

  5. 21 CFR 1305.13 - Procedure for filling DEA Forms 222.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Procedure for filling DEA Forms 222. 1305.13... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.13 Procedure for filling DEA Forms 222. (a) A purchaser must submit Copy 1 and Copy 2 of the DEA Form 222 to the supplier and retain Copy 3 in...

  6. 21 CFR 1305.19 - Cancellation and voiding of DEA Forms 222.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Cancellation and voiding of DEA Forms 222. 1305.19... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.19 Cancellation and voiding of DEA Forms 222. (a) A purchaser may cancel part or all of an order on a DEA Form 222 by notifying the supplier...

  7. 21 CFR 1305.12 - Procedure for executing DEA Forms 222.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Procedure for executing DEA Forms 222. 1305.12... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.12 Procedure for executing DEA Forms 222. (a) A purchaser must prepare and execute a DEA Form 222 simultaneously in triplicate by means of...

  8. 21 CFR 1305.19 - Cancellation and voiding of DEA Forms 222.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Cancellation and voiding of DEA Forms 222. 1305.19... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.19 Cancellation and voiding of DEA Forms 222. (a) A purchaser may cancel part or all of an order on a DEA Form 222 by notifying the supplier...

  9. 21 CFR 1305.14 - Procedure for endorsing DEA Forms 222.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Procedure for endorsing DEA Forms 222. 1305.14... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.14 Procedure for endorsing DEA Forms 222. (a) A DEA Form 222, made out to any supplier who cannot fill all or a part of the order within the...

  10. 21 CFR 1305.15 - Unaccepted and defective DEA Forms 222.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Unaccepted and defective DEA Forms 222. 1305.15... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.15 Unaccepted and defective DEA Forms 222. (a) A DEA Form 222 must not be filled if either of the following apply: (1) The order is not...

  11. 21 CFR 1305.12 - Procedure for executing DEA Forms 222.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Procedure for executing DEA Forms 222. 1305.12... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.12 Procedure for executing DEA Forms 222. (a) A purchaser must prepare and execute a DEA Form 222 simultaneously in triplicate by means of...

  12. 21 CFR 1305.15 - Unaccepted and defective DEA Forms 222.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Unaccepted and defective DEA Forms 222. 1305.15... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.15 Unaccepted and defective DEA Forms 222. (a) A DEA Form 222 must not be filled if either of the following apply: (1) The order is not...

  13. 21 CFR 1305.13 - Procedure for filling DEA Forms 222.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Procedure for filling DEA Forms 222. 1305.13... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.13 Procedure for filling DEA Forms 222. (a) A purchaser must submit Copy 1 and Copy 2 of the DEA Form 222 to the supplier and retain Copy 3 in...

  14. 21 CFR 1305.13 - Procedure for filling DEA Forms 222.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Procedure for filling DEA Forms 222. 1305.13... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.13 Procedure for filling DEA Forms 222. (a) A purchaser must submit Copy 1 and Copy 2 of the DEA Form 222 to the supplier and retain Copy 3 in...

  15. 21 CFR 1305.12 - Procedure for executing DEA Forms 222.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Procedure for executing DEA Forms 222. 1305.12... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.12 Procedure for executing DEA Forms 222. (a) A purchaser must prepare and execute a DEA Form 222 simultaneously in triplicate by means of...

  16. 21 CFR 1305.18 - Return of unused DEA Forms 222.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Return of unused DEA Forms 222. 1305.18 Section... II CONTROLLED SUBSTANCES DEA Form 222 § 1305.18 Return of unused DEA Forms 222. If the registration... substances for which the purchaser is registered, the purchaser must return all unused DEA Forms 222 to...

  17. 21 CFR 1305.15 - Unaccepted and defective DEA Forms 222.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Unaccepted and defective DEA Forms 222. 1305.15... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.15 Unaccepted and defective DEA Forms 222. (a) A DEA Form 222 must not be filled if either of the following apply: (1) The order is not...

  18. 21 CFR 1305.14 - Procedure for endorsing DEA Forms 222.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Procedure for endorsing DEA Forms 222. 1305.14... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.14 Procedure for endorsing DEA Forms 222. (a) A DEA Form 222, made out to any supplier who cannot fill all or a part of the order within the...

  19. 21 CFR 1305.19 - Cancellation and voiding of DEA Forms 222.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Cancellation and voiding of DEA Forms 222. 1305.19... I AND II CONTROLLED SUBSTANCES DEA Form 222 § 1305.19 Cancellation and voiding of DEA Forms 222. (a) A purchaser may cancel part or all of an order on a DEA Form 222 by notifying the supplier...

  20. 21 CFR 1305.16 - Lost and stolen DEA Forms 222.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Lost and stolen DEA Forms 222. 1305.16 Section... II CONTROLLED SUBSTANCES DEA Form 222 § 1305.16 Lost and stolen DEA Forms 222. (a) If a purchaser ascertains that an unfilled DEA Form 222 has been lost, he or she must execute another in triplicate...

  1. 21 CFR 1305.18 - Return of unused DEA Forms 222.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Return of unused DEA Forms 222. 1305.18 Section... II CONTROLLED SUBSTANCES DEA Form 222 § 1305.18 Return of unused DEA Forms 222. If the registration... substances for which the purchaser is registered, the purchaser must return all unused DEA Forms 222 to...

  2. Pharmacists correcting schedule II prescriptions: DEA flip-flops continue.

    PubMed

    Abood, Richard R

    2010-12-01

    The Drug Enforcement Administration (DEA) has in recent years engaged in flip-flopping over important policy decisions. The most recent example involved whether a pharmacist can correct a written schedule II prescription upon verification with the prescriber. For several years the DEA's policy permitted this practice. Then the DEA issued a conflicting policy statement in 2007 in the preamble to the multiple schedule II prescription regulation, causing a series of subsequent contradictory statements ending with the policy that pharmacists should follow state law or policy until the Agency issues a regulation. It is doubtful that the DEA's opinion in the preamble would in itself constitute legal authority, or that the Agency would try to enforce the opinion. Nonetheless, these flip-flop opinions have confused pharmacists, caused some pharmacies to have claims rejected by third party payors, and most likely have inconvenienced patients.

  3. DEA issues proposed rule on e-prescribing.

    PubMed

    Ball, Frederick R

    2009-01-01

    On June 27, 2008, the Drug Enforcement Administration (DEA) released a Notice of Proposed Rulemaking. In an effort to modernize the regulation of controlled substances, the DEA is proposing an amendment to its regulations that would permit practitioners to write and pharmacies to dispense and archive prescriptions of controlled substances electronically. The new regulations aim to promote accuracy and efficiency. This article discusses that proposed rule.

  4. Importance of Statistical Evidence in Estimating Valid DEA Scores.

    PubMed

    Barnum, Darold T; Johnson, Matthew; Gleason, John M

    2016-03-01

    Data Envelopment Analysis (DEA) allows healthcare scholars to measure productivity in a holistic manner. It combines a production unit's multiple outputs and multiple inputs into a single measure of its overall performance relative to other units in the sample being analyzed. It accomplishes this task by aggregating a unit's weighted outputs and dividing the output sum by the unit's aggregated weighted inputs, choosing output and input weights that maximize its output/input ratio when the same weights are applied to other units in the sample. Conventional DEA assumes that inputs and outputs are used in different proportions by the units in the sample. So, for the sample as a whole, inputs have been substituted for each other and outputs have been transformed into each other. Variables are assigned different weights based on their marginal rates of substitution and marginal rates of transformation. If in truth inputs have not been substituted nor outputs transformed, then there will be no marginal rates and therefore no valid basis for differential weights. This paper explains how to statistically test for the presence of substitutions among inputs and transformations among outputs. Then, it applies these tests to the input and output data from three healthcare DEA articles, in order to identify the effects on DEA scores when input substitutions and output transformations are absent in the sample data. It finds that DEA scores are badly biased when substitution and transformation are absent and conventional DEA models are used.

  5. DEA best practice assesses relative efficiency, profitability

    SciTech Connect

    Taylor, D.T.; Thompson, R.G.

    1995-11-13

    The US Federal Energy Regulatory Commission (FERC), in its Order 636 of Apr. 8, 1992, stated, ``All natural gas suppliers, including pipelines, will compete for gas purchases on an equal footing.`` This FERC order changed the economic environment in the natural gas pipeline industry. Now, gas pipeline companies must know their market position, since rate of return regulation is no longer relevant. They must be managed more than before as companies have been in less-regulated parts of the oil and gas business. How they adapt to the new environment, therefore, can be instructive to companies throughout the energy industry. In this article, DEA best-practice methods measure relative efficiency and profitability potential. This measurement reflects fundamental economic relationships. The operational efficiency model analyzed is as follows: Y{sub 1} = f(x{sub 1}, x{sub 2}), where Y{sub 1} is gross profits, x{sub 1} is total assets (capital employed), and x{sub 2} is total employees (labor employed). Y{sub 1} is a comprehensive indicator of a pipeline`s output, whereas x{sub 1} represents the pipeline`s total capital employed, and x{sub 2} represents the pipeline`s total labor employed. This model reflects principles long studied in economics.

  6. Tactile feedback to the palm using arbitrarily shaped DEA

    NASA Astrophysics Data System (ADS)

    Mößinger, Holger; Haus, Henry; Kauer, Michaela; Schlaak, Helmut F.

    2014-03-01

    Tactile stimulation enhances user experience and efficiency in human machine interaction by providing information via another sensory channel to the human brain. DEA as tactile interfaces have been in the focus of research in recent years. Examples are (vibro-) tactile keyboards or Braille displays. These applications of DEA focus mainly on interfacing with the user's fingers or fingertips only - demonstrating the high spatial resolution achievable with DEA. Besides providing a high resolution, the flexibility of DEA also allows designing free form surfaces equipped with single actuators or actuator matrices which can be fitted to the surface of the human skin. The actuators can then be used to provide tactile stimuli to different areas of the body, not to the fingertips only. Utilizing and demonstrating this flexibility we designed a free form DEA pad shaped to fit into the inside of the human palm. This pad consists of four single actuators which can provide e.g. directional information such as left, right, up and down. To demonstrate the value of such free form actuators we manufactured a PC-mouse using 3d printing processes. The actuator pad is mounted on the back of the mouse, resting against the palm while operating it. Software on the PC allows control of the vibration patterns displayed by the actuators. This allows helping the user by raising attention to certain directions or by discriminating between different modes like "pick" or "manipulate". Results of first tests of the device show an improved user experience while operating the PC mouse.

  7. Converting to DEA/MDEA mix ups sweetening capacity

    SciTech Connect

    Spears, M.L.; Hagan, K.M.; Bullin, J.A.; Michalik, C.J.

    1996-08-12

    Mixing amines can be the best method for increasing capacity or improving efficiency in an amine sweetening unit. In many cases, it may be possible simply to add a second amine to the existing solution on the fly, or as the unit is running. Union Pacific Resources` Bryan, Tex., gas plant provides one example. The plant was converted from diethanolamine (DEA) to a DEA/MDEA (methyl DEA) mixture after analysis by TSWEET, a process-simulation program. After conversion, CO{sub 2} levels in the sales gas fell to less than pipeline specifications. Data were taken for the absorber at a constant amine circulation of 120 gpm. A comparison of the performance data to the values calculated by the program proved the accuracy of TSWEET. The conversion and performance of the plant are described.

  8. 78 FR 17778 - Proposed Information Collection (Dependents' Educational Assistance (DEA) Election Request...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-22

    ... forms of information technology. Title: Dependents' Educational Assistance (DEA) Election Request, VA... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF VETERANS AFFAIRS Proposed Information Collection (Dependents' Educational Assistance (DEA) Election...

  9. Analysis of Organizational Learning Efficiency in Enterprises Based on DEA

    NASA Astrophysics Data System (ADS)

    Jiang, Tianying; Bai, Zhixin

    The study assesses the organizational learning efficiency in 30 large-scale enterprises of Zhejiang Province, making use of DEA assessment method. The results show that the entire organizational learning efficiency of zhejiang province's large-scale enterprises is in need; only part of the enterprises are DEA valid, and the results of the study basically fit in with the enterprises' practical situation. It is thus clear that the new way to assess the efficiency of organizational learning in enterprises is rational and accessible, which provides an important instrument to enterprises' management decision making.

  10. DoDEA 2010-11 Customer Satisfaction Survey. Executive Summary

    ERIC Educational Resources Information Center

    Department of Defense Education Activity, 2011

    2011-01-01

    Every two years the Department of Defense Education Activity (DoDEA) administers the DoDEA Customer Satisfaction Survey (CSS) to all parents with children attending DoDEA schools and all 4th-12th grade students enrolled in a DoDEA school. Parents were asked to complete one survey for each school in which they had a child enrolled. The purpose of…

  11. Dependents' Educational Assistance Program (DEA), Chapter 25 of Title 38, U.S. Code

    ERIC Educational Resources Information Center

    US Department of Veterans Affairs, 2005

    2005-01-01

    This pamphlet provides a general description of the Dependents' Educational Assistance program, or DEA (chapter 35 of title 38, U. S. Code). The DEA program provides education and training opportunities to eligible dependents and survivors of certain veterans. It covers the main questions prospective participants may have about DEA benefits,…

  12. 75 FR 56661 - Agency Information Collection (Dependents' Educational Assistance (DEA) Election Request...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-16

    ... AFFAIRS Agency Information Collection (Dependents' Educational Assistance (DEA) Election Request) Activity...: Dependents' Educational Assistance (DEA) Election Request, VA Form Letter 22-909. OMB Control Number: 2900... dependents of veterans receiving DEA benefits of their option to elect a beginning date to start their...

  13. 75 FR 39620 - Proposed Information Collection (Dependents' Educational Assistance (DEA) Election Request...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-09

    ... AFFAIRS Proposed Information Collection (Dependents' Educational Assistance (DEA) Election Request... information needed to determine dependents of veterans beginning date to start their DEA benefits. DATES... (DEA) Election Request, VA Form Letter 22-909. OMB Control Number: 2900-0703. Type of Review:...

  14. SY 2008-09 Customer Satisfaction Survey Results (Full Report). DoDEA Results

    ERIC Educational Resources Information Center

    Department of Defense Education Activity, 2009

    2009-01-01

    The Department of Defense Education Activity (DoDEA) Customer Satisfaction Survey is a biennial survey administered by DoDEA to parents and students to monitor DoDEA's success in meeting students' needs. The survey is administered every other year to sponsors with children in pre-kindergarten--12th grade and to students in grades 4-12. For the…

  15. SY 2010-11 Customer Satisfaction Survey Results (Full Report). DoDEA Results

    ERIC Educational Resources Information Center

    Department of Defense Education Activity, 2011

    2011-01-01

    The Department of Defense Education Activity (DoDEA) Customer Satisfaction Survey is a biennial survey administered by DoDEA to parents and students to monitor DoDEA's success in meeting students' needs. The survey is administered every other year to sponsors with children in pre-kindergarten-12th grade and to students in grades 4-12. For the…

  16. 21 CFR 1321.01 - DEA mailing addresses.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... cancellation1307.03—Exception request filing. 1307.22—Disposal of controlled substances by the Administration... machines refused, rejected, or returned. 1312.12(a)—Application for import permit (DEA Form 357). 1312.16(b... refused, rejected or undeliverable. 1313.31(b)—Advanced notice of importation for transshipment...

  17. 21 CFR 1321.01 - DEA mailing addresses.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... cancellation1307.03—Exception request filing. 1307.22—Disposal of controlled substances by the Administration... machines refused, rejected, or returned. 1312.12(a)—Application for import permit (DEA Form 357). 1312.16(b... refused, rejected or undeliverable. 1313.31(b)—Advanced notice of importation for transshipment...

  18. DoDEA Seniors' Postsecondary Plans and Scholarships, 2009

    ERIC Educational Resources Information Center

    Embler, Sandra; Graves, Stacy

    2009-01-01

    This report summarizes the postsecondary intentions and scholarship monies earned by high school graduates of the Department of Defense Education Activity (DoDEA) in SY08-09. As part of the process for planning for postsecondary life, seniors indicate whether they are planning to attend a 4-year college/university, junior/community college, or…

  19. DoDEA Seniors' Postsecondary Plans and Scholarships, 2010

    ERIC Educational Resources Information Center

    Embler, Sandra

    2010-01-01

    During their senior year students in the Department of Defense Education Activity (DoDEA) schools develop a postsecondary plan. This plan outlines what students intend to do after graduating from high school; whether they are planning to attend a 4-year college/university, junior/community college, or vocational/technical school; seek employment…

  20. DoDEA 2007 Postsecondary Plans and Scholarships Report

    ERIC Educational Resources Information Center

    Department of Defense Education Activity, 2007

    2007-01-01

    This report presents a summary of postsecondary plans and scholarship monies of graduates of Department of Defense Education Activity (DoDEA) high school seniors in SY06-07. Postsecondary plans represent the intentions of seniors the year after graduation; students indicate whether they are planning on attending a 4-year College/University,…

  1. DoDEA Seniors' Postsecondary Plans and Scholarships, 2008

    ERIC Educational Resources Information Center

    Department of Defense Education Activity, 2008

    2008-01-01

    This report summarizes the postsecondary plans and scholarship monies of graduates of Department of Defense Education Activity (DoDEA) high school seniors in SY07-08. Postsecondary plans represent the intentions of seniors the year after graduation. Students indicate whether they plan to attend a 4-year college/university, junior/community…

  2. DoDEA 2006 Postsecondary Plans and Scholarships Report

    ERIC Educational Resources Information Center

    Department of Defense Education Activity, 2006

    2006-01-01

    At the end of every school year, each high school in the Department of Defense Education Activity (DoDEA) is required to document the postsecondary plans and scholarships of twelfth grade students. This report provides a summary of these data, including the postsecondary plans of students and the monies offered and accepted by these students for…

  3. Amiodarone increases the accumulation of DEA in a human alveolar epithelium-derived cell line.

    PubMed

    Seki, Satoru; Itagaki, Shirou; Kobayashi, Masaki; Hirano, Takeshi; Iseki, Ken

    2008-07-01

    Amiodarone (AMD)-induced pulmonary toxicity (AIPT) is the most life-threatening side-effect of AMD treatment. N-Monodesethylamiodarone (DEA), an active metabolite of AMD, also exhibits cytotoxicity and tends to accumulate in the lung more intensively than AMD. In this study, we characterized the mechanism of DEA accumulation using A549 cells as a model of the alveolar epithelium. Typical ATP-depletion compounds caused an approximately 30% increase in the accumulation of DEA in A549 cells, although these effects were less than those in Caco-2 cells. Triiodothyronine (T(3)), which exhibited an inhibitory effect on DEA efflux in Caco-2 cells, did not affect the accumulation of DEA in A549 cells. On the other hand, 100 microM AMD caused an approximately 200% increase in DEA content in A549 cells, although AMD accumulation was not affected by 100 microM DEA. Since the reducing effect of AMD on cellular ATP levels and that of FCCP were similar, the mechanism by which DEA accumulation is increased by AMD might be different from the ATP-dependent DEA efflux mechanism. The decrease in cell viability by DEA in the presence of AMD (IC(50) value of DEA for A549 cell viability: 25.4+/-2.4 microM) was more pronounced than that by DEA alone (IC(50) value: 11.5+/-3.0 microM). This further DEA accumulation by AMD might be a factor responsible for the greater accumulation of DEA than that of AMD in the lung in long-term AMD-treated patients.

  4. Thermal analysis of optical polymers; DMA, MDSC and DEA

    SciTech Connect

    Harmon, J.P.; Bertolucci, P.; Gao, Hang

    1995-12-01

    A series of high refractive index, alkylated styrene polymers used in optical fibers cores is characterized along with a transparent, fluorinated alkyl methacrylate cladding polymer. The polymers were characterized by dynamic mechanical analysis (DMA), dielectric analysis (DEA) and modulated differential scanning calorimetry(MDSC). Poly(2,2,2-trifluoroethyl methacrylate) exhibited alpha, beta, and gamma transitions in the DMA and DEA spectra. These were shifted to higher temperatures than those observed in poly(ethyl methacrylate) over most of the frequencies. MDSC was used to generate reversible and irreversible heat flow versus temperature curves. These curves were used to separate the enthalpic relaxation from the glass transition for a series of these optical polymers aged at different times and temperatures.

  5. A smart experimental technique for the optimization of dielectric elastomer actuator (DEA) systems

    NASA Astrophysics Data System (ADS)

    Hodgins, M.; Rizzello, G.; York, A.; Naso, D.; Seelecke, S.

    2015-09-01

    In order to aid in moving dielectric elastomer actuator (DEA) technology from the laboratory into a commercial product DEA prototypes should be tested against a variety of loading conditions and eventually in the end user conditions. An experimental test setup to seamlessly perform mechanical characterization and loading of the DEA would be a great asset toward this end. Therefore, this work presents the design, control and systematic validation of a benchtop testing station for miniature silicon based circular DEAs. A versatile benchtop tester is able to characterize and apply programmable loading forces to the DEA while measuring actuator performance. The tester successfully applied mechanical loads to the DEA (including positive, constant and negative stiffness loads) simulating biasing systems via an electromagnetic linear motor operating in closed loop with a force/mechanical impedance control scheme. The tester expedites mechanical testing of the DEA by eliminating the need to build intricate pre-load mechanisms or use multiple testing jigs for characterizing the DEA response. The results show that proper mechanical loading of the DEA increases the overall electromechanical sensitivity of the system and thereby the actuator output. This approach to characterize and apply variable loading forces to DEAs in a single test system will enable faster realization of higher performance actuators.

  6. Activity, specificity, and titer of naturally occurring canine anti-DEA 7 antibodies.

    PubMed

    Spada, Eva; Proverbio, Daniela; Baggiani, Luciana; Canzi, Ilaria; Perego, Roberta

    2016-11-01

    The reported prevalence of naturally occurring anti-dog erythrocyte antigen (DEA) 7 antibodies in DEA 7-negative dogs is as high as 50%. Characterization of these antibodies may better define their importance in canine transfusion medicine. We determined in vitro activity, specificity, and titer of anti-DEA 7 antibodies in DEA 7-negative dogs. Plasma samples from 317 DEA 7-negative dogs were cross-matched with DEA 7-positive red blood cells (RBCs) using gel column technology. Agglutination occurred with DEA 7-positive RBCs but not with DEA 7-negative RBCs in 73 samples (23%), which were hence classified as containing anti-DEA 7 antibodies. These samples were evaluated for hemolytic and agglutinating activity, strength of agglutination, and antibody specificity and titers. All samples showed agglutination but none showed hemolysis. Gel agglutination was graded as 1+ for 20 samples (27%), 2+ for 49 samples (67%), 3+ for 4 samples (6%); no samples were graded 4+. The agglutination titer was <1:2 for 51 samples (73%), 1:2 for 13 samples (19%), 1:4 for 4 samples (5%), and 1:8 for 2 samples (3%). Of 16 samples treated with 2-mercaptoethanol, 11 samples (69%) contained only IgM, 4 samples (25%) exhibited only IgG activity, and 1 sample (6%) had both IgG and IgM activity. Low titers of warm, weakly agglutinating, mostly naturally occurring IgM anti-DEA 7 antibodies were found in 23% of DEA 7-negative dogs. The presence of naturally occurring anti-DEA 7 antibodies suggests that cross-matching of canine blood recipients is advisable, even at first transfusion, to minimize delayed transfusion reactions.

  7. Measurement of returns to scale in radial DEA models

    NASA Astrophysics Data System (ADS)

    Krivonozhko, V. E.; Lychev, A. V.; Førsund, F. R.

    2017-01-01

    A general approach is proposed in order to measure returns to scale and scale elasticity at projections points in the radial data envelopment analysis (DEA) models. In the first stage, a relative interior point belonging to the optimal face is found using a special, elaborated method. In previous work it was proved that any relative interior point of a face has the same returns to scale as any other interior point of this face. In the second stage, we propose to determine the returns to scale at the relative interior point found in the first stage.

  8. 28 CFR 16.98 - Exemption of the Drug Enforcement Administration (DEA)-limited access.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... investigations and impede the development of criminal intelligence necessary for effective law enforcement. (8...)(1): (1) Air Intelligence Program (Justice/DEA-001) (2) Clandestine Laboratory Seizure System (CLSS... Intelligence Program (Justice/DEA-001); Clandestine Laboratory Seizure System (CLSS)...

  9. 28 CFR 16.98 - Exemption of the Drug Enforcement Administration (DEA)-limited access.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... investigations and impede the development of criminal intelligence necessary for effective law enforcement. (8...)(1): (1) Air Intelligence Program (Justice/DEA-001) (2) Clandestine Laboratory Seizure System (CLSS... Intelligence Program (Justice/DEA-001); Clandestine Laboratory Seizure System (CLSS)...

  10. 75 FR 10671 - Changes to and Consolidation of DEA Mailing Addresses

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-09

    ...DEA is amending Title 21 of the Code of Federal Regulations (CFR) to update and consolidate existing mailing addresses. Mailing addresses are being removed from the individual sections in which they currently appear and are being consolidated into one table in a new part 1321. DEA is making this change to the CFR to ensure registrants have the most current and accurate information, reduce......

  11. DEA material enhancement with dipole grafted PDMS networks

    NASA Astrophysics Data System (ADS)

    Risse, Sebastian; Kussmaul, Björn; Krüger, Hartmut; Waché, Rémi; Kofod, Guggi

    2011-04-01

    Silicone elastomers are highly suitable for application in the field of dielectric elastomer actuators (DEA) due to their unique material properties (e.g. low glass temperature, thermal stability, large capability of chemical tailoring). The elastomer forming Polydimethysiloxane (PDMS) employed for this study consists of chains with vinyl termination and is cross linked via hydrosilylation to a cross linking molecule in the presence of platinum catalyst. Here, dipole molecules (N-Allyl-N-methyl-4-nitroaniline) were specifically synthesized such that they could chemically graft to the silicone network. The most prominent advantage of this approach is the achievement of a homogeneous distribution of dipoles in the PDMS matrix and a suppression of phase separation due to the grafting to the junction points of the rubber network. Several films with dipole contents ν ranging from 0 %wt up to 10.9 %wt were prepared. The films were investigated to determine their mechanical (tensile testing), dielectric (dielectric relaxation spectroscopy) and electrical (electrical breakdown) properties. This new approach for composites on the molecular level leads to homogeneous films with enhanced material properties for DEA applications. An increase in permittivity from 3.3 to 6.0, a decrease in electrical breakdown from 130 V/μm to 50 V/μm and a lowering of the mechanical stiffness from 1700 kPa to 300 kPa was observed.

  12. Relative performance of academic departments using DEA with sensitivity analysis.

    PubMed

    Tyagi, Preeti; Yadav, Shiv Prasad; Singh, S P

    2009-05-01

    The process of liberalization and globalization of Indian economy has brought new opportunities and challenges in all areas of human endeavor including education. Educational institutions have to adopt new strategies to make best use of the opportunities and counter the challenges. One of these challenges is how to assess the performance of academic programs based on multiple criteria. Keeping this in view, this paper attempts to evaluate the performance efficiencies of 19 academic departments of IIT Roorkee (India) through data envelopment analysis (DEA) technique. The technique has been used to assess the performance of academic institutions in a number of countries like USA, UK, Australia, etc. But we are using it first time in Indian context to the best of our knowledge. Applying DEA models, we calculate technical, pure technical and scale efficiencies and identify the reference sets for inefficient departments. Input and output projections are also suggested for inefficient departments to reach the frontier. Overall performance, research performance and teaching performance are assessed separately using sensitivity analysis.

  13. The application of DEA model in enterprise environmental performance auditing

    NASA Astrophysics Data System (ADS)

    Li, F.; Zhu, L. Y.; Zhang, J. D.; Liu, C. Y.; Qu, Z. G.; Xiao, M. S.

    2017-01-01

    As a part of society, enterprises have an inescapable responsibility for environmental protection and governance. This article discusses the feasibility and necessity of enterprises environmental performance auditing and uses DEA model calculate the environmental performance of Haier for example. The most of reference data are selected and sorted from Haier’s environmental reportspublished in 2008, 2009, 2011 and 2015, and some of the data from some published articles and fieldwork. All the calculation results are calculated by DEAP software andhave a high credibility. The analysis results of this article can give corporate managements an idea about using environmental performance auditing to adjust their corporate environmental investments capital quota and change their company’s environmental strategies.

  14. Mathematics Audit of the DoDEA Schools: 2014-2015

    DTIC Science & Technology

    2016-01-01

    Mathematics Audit of the DoDEA Schools 2014–2015 Rita Karam, Brian M. Stecher, Tiffany Tsai, Geoffrey Grimm, Jonathan Schweig C O R P O R A T I O N...the Common Core State Standards in mathematics (to which DoDEA refers as the College and Career Readiness [CCR] standards). Efforts to change from...the 2009 DoDEA mathematics standards to the CCR standards began in earnest during the 2014–2015 school year, with the CCR mathematics standards to be

  15. Modeling and notation of DEA with strong and weak disposable outputs.

    PubMed

    Kuntz, Ludwig; Sülz, Sandra

    2011-12-01

    Recent articles published in Health Care Management Science have described DEA applications under the assumption of strong and weak disposable outputs. As we confidently assume that these papers include some methodical deficiencies, we aim to illustrate a revised approach.

  16. Novel DEA with organically modified silicone elastomer for permittivity enhancement

    NASA Astrophysics Data System (ADS)

    Böse, Holger; Uhl, Detlev; Rabindranath, Raman

    2012-04-01

    Dielectric elastomer actuators (DEA) based on an organically modified silicone elastomer are introduced. The elastomer carries fluorinated sidegroups in the polysiloxane molecular chain and is synthesized from precursors which all are fluorinated. A fluorinated silicone oil is added in consecutive concentration steps as a softening agent. The electric properties of the modified silicone elastomers in terms of the permittivity, specific conductivity and electric breakdown field strength were investigated and compared with those of the unmodified silicone elastomer as the reference material. Moreover, the mechanical characteristics like Young's modulus in tensile and compressional load as well as the storage and loss modulus in shear load were studied. The permittivity of the modified silicone is enhanced by 80 % compared to the unmodified silicone elastomer. No strong alteration of the specific conductivity occurs. The electric breakdown field strength is comparable to that of the reference material. Simultaneously, the Young's modulus is decreased by the softening agent. Actuation measurements on model actuators show, that the actuation strain of the best materials surmounts that of the unmodified reference material by a factor of up to 5. The modified silicone elastomer materials can also be used for dielectric elastomer sensors and generators.

  17. Facile method to prepare poly(S-co-HEA)/Ag nanocomposite particles with high efficient catalytic activity and surface enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Chao, Zhiyin; Wang, Lan; Song, Linyong; Zhou, Yifeng; Nie, Wangyan; Chen, Pengpeng

    2015-02-01

    Surface hydroxyl-functionalized poly(styrene-co-hydroxyethyl acrylate) [P(S-co-HEA)] microsphere were used to prepare P(S-co-HEA)/silver composite particles. Based on the weak interaction between silver ions and hydroxyl, silver ions were adsorbed onto the polymer surface and reduced by diethanolamine (DEA). The morphology of P(S-co-HEA)/Ag was easily controlled by the molar ratio of DEA/AgNO3. The composite particles were characterized by SEM, XRD, and UV-vis spectroscopy. The obtained P(S-co-HEA)/Ag particles with small and denser silver nanoparticles showed a high efficient activity to catalyze reduction of methylene blue (MB). While the P(S-co-HEA)/Ag particles with big and denser silver nanoparticles showed highly sensitive Raman enhanced performance.

  18. Software for Automated Reading of STEP Files by I-DEAS(trademark)

    NASA Technical Reports Server (NTRS)

    Pinedo, John

    2003-01-01

    A program called "readstep" enables the I-DEAS(tm) computer-aided-design (CAD) software to automatically read Standard for the Exchange of Product Model Data (STEP) files. (The STEP format is one of several used to transfer data between dissimilar CAD programs.) Prior to the development of "readstep," it was necessary to read STEP files into I-DEAS(tm) one at a time in a slow process that required repeated intervention by the user. In operation, "readstep" prompts the user for the location of the desired STEP files and the names of the I-DEAS(tm) project and model file, then generates an I-DEAS(tm) program file called "readstep.prg" and two Unix shell programs called "runner" and "controller." The program "runner" runs I-DEAS(tm) sessions that execute readstep.prg, while "controller" controls the execution of "runner" and edits readstep.prg if necessary. The user sets "runner" and "controller" into execution simultaneously, and then no further intervention by the user is required. When "runner" has finished, the user should see only parts from successfully read STEP files present in the model file. STEP files that could not be read successfully (e.g., because of format errors) should be regenerated before attempting to read them again.

  19. Effects of the nitric oxide donor, DEA/NO on cortical spreading depression.

    PubMed

    Wang, M; Obrenovitch, T P; Urenjak, J

    2003-06-01

    Cortical spreading depression (CSD) is a transient disruption of local ionic homeostasis that may promote migraine attacks and the progression of stroke lesions. We reported previously that the local inhibition of nitric oxide (NO) synthesis with Nomega-nitro-L-arginine methyl ester (L-NAME) delayed markedly the initiation of the recovery of ionic homeostasis from CSD. Here we describe a novel method for selective, controlled generation of exogenous NO in a functioning brain region. It is based on microdialysis perfusion of the NO donor, 2-(N,N-diethylamino)-diazenolate-2-oxide (DEA/NO). As DEA/NO does not generate NO at alkaline pH, and as the brain has a strong acid-base buffering capacity, DEA/NO was perfused in a medium adjusted at alkaline (but unbuffered) pH. Without DEA/NO, such a microdialysis perfusion medium did not alter CSD. DEA/NO (1, 10 and 100 microM) had little effect on CSD by itself, but it reversed in a concentration-dependent manner the effects of NOS inhibition by 1 mM L-NAME. These data demonstrate that increased formation of endogenous NO associated with CSD is critical for subsequent, rapid recovery of cellular ionic homeostasis. In this case, the molecular targets for NO may be located either on brain cells to suppress mechanisms directly involved in CSD genesis, or on local blood vessels to couple flow to the increased energy demand associated with CSD.

  20. Technical and scale efficiency in public and private Irish nursing homes - a bootstrap DEA approach.

    PubMed

    Ni Luasa, Shiovan; Dineen, Declan; Zieba, Marta

    2016-10-27

    This article provides methodological and empirical insights into the estimation of technical efficiency in the nursing home sector. Focusing on long-stay care and using primary data, we examine technical and scale efficiency in 39 public and 73 private Irish nursing homes by applying an input-oriented data envelopment analysis (DEA). We employ robust bootstrap methods to validate our nonparametric DEA scores and to integrate the effects of potential determinants in estimating the efficiencies. Both the homogenous and two-stage double bootstrap procedures are used to obtain confidence intervals for the bias-corrected DEA scores. Importantly, the application of the double bootstrap approach affords true DEA technical efficiency scores after adjusting for the effects of ownership, size, case-mix, and other determinants such as location, and quality. Based on our DEA results for variable returns to scale technology, the average technical efficiency score is 62 %, and the mean scale efficiency is 88 %, with nearly all units operating on the increasing returns to scale part of the production frontier. Moreover, based on the double bootstrap results, Irish nursing homes are less technically efficient, and more scale efficient than the conventional DEA estimates suggest. Regarding the efficiency determinants, in terms of ownership, we find that private facilities are less efficient than the public units. Furthermore, the size of the nursing home has a positive effect, and this reinforces our finding that Irish homes produce at increasing returns to scale. Also, notably, we find that a tendency towards quality improvements can lead to poorer technical efficiency performance.

  1. Review of life-cycle approaches coupled with data envelopment analysis: launching the CFP + DEA method for energy policy making.

    PubMed

    Vázquez-Rowe, Ian; Iribarren, Diego

    2015-01-01

    Life-cycle (LC) approaches play a significant role in energy policy making to determine the environmental impacts associated with the choice of energy source. Data envelopment analysis (DEA) can be combined with LC approaches to provide quantitative benchmarks that orientate the performance of energy systems towards environmental sustainability, with different implications depending on the selected LC + DEA method. The present paper examines currently available LC + DEA methods and develops a novel method combining carbon footprinting (CFP) and DEA. Thus, the CFP + DEA method is proposed, a five-step structure including data collection for multiple homogenous entities, calculation of target operating points, evaluation of current and target carbon footprints, and result interpretation. As the current context for energy policy implies an anthropocentric perspective with focus on the global warming impact of energy systems, the CFP + DEA method is foreseen to be the most consistent LC + DEA approach to provide benchmarks for energy policy making. The fact that this method relies on the definition of operating points with optimised resource intensity helps to moderate the concerns about the omission of other environmental impacts. Moreover, the CFP + DEA method benefits from CFP specifications in terms of flexibility, understanding, and reporting.

  2. The Impact of Size and Specialisation on Universities' Department Performance: A DEA Analysis Applied to Austrian Universities

    ERIC Educational Resources Information Center

    Leitner, Karl-Heinz; Prikoszovits, Julia; Schaffhauser-Linzatti, Michaela; Stowasser, Rainer; Wagner, Karin

    2007-01-01

    This paper explores the performance efficiency of natural and technical science departments at Austrian universities using Data Envelopment Analysis (DEA). We present DEA as an alternative tool for benchmarking and ranking the assignment of decision-making units (organisations and organisational units). The method applies a multiple input and…

  3. Review of Life-Cycle Approaches Coupled with Data Envelopment Analysis: Launching the CFP + DEA Method for Energy Policy Making

    PubMed Central

    Vázquez-Rowe, Ian

    2015-01-01

    Life-cycle (LC) approaches play a significant role in energy policy making to determine the environmental impacts associated with the choice of energy source. Data envelopment analysis (DEA) can be combined with LC approaches to provide quantitative benchmarks that orientate the performance of energy systems towards environmental sustainability, with different implications depending on the selected LC + DEA method. The present paper examines currently available LC + DEA methods and develops a novel method combining carbon footprinting (CFP) and DEA. Thus, the CFP + DEA method is proposed, a five-step structure including data collection for multiple homogenous entities, calculation of target operating points, evaluation of current and target carbon footprints, and result interpretation. As the current context for energy policy implies an anthropocentric perspective with focus on the global warming impact of energy systems, the CFP + DEA method is foreseen to be the most consistent LC + DEA approach to provide benchmarks for energy policy making. The fact that this method relies on the definition of operating points with optimised resource intensity helps to moderate the concerns about the omission of other environmental impacts. Moreover, the CFP + DEA method benefits from CFP specifications in terms of flexibility, understanding, and reporting. PMID:25654136

  4. The impact of non-discretionary factors on DEA and SFA technical efficiency differences.

    PubMed

    Kontodimopoulos, Nick; Papathanasiou, Nikolaos D; Flokou, Angeliki; Tountas, Yannis; Niakas, Dimitris

    2011-10-01

    The purpose of this study was to examine if factors of the external operating environment can explain differences in technical efficiency derived from Data Envelopment Analysis (DEA) and Stochastic Frontier Analysis (SFA). In a sample of 124 dialysis facilities, technical efficiency was compared according to ownership, region, years in operation and size. With second-stage Tobit regression, DEA and SFA efficiency was regressed against these environmental factors to determine their potential for predicting technical efficiency, as well as the efficiency differences between the two frontier methods. DEA expectedly generated lower mean efficiency scores than SFA (68.2% vs. 79.4%, P < 0.001), due to the "random effects" term computed by the latter, in addition to "true" inefficiency. This finding was consistent for the subgroups formed on the basis of the environmental factors. Half the variation in the DEA-SFA efficiency differences was explained by environmental factors. This suggests that in addition to market instabilities, luck, and other related phenomena, decision-makers in their effort to determine optimal resource allocation, should point their attention to the potentially useful insight provided by environmental factors.

  5. Selected Private Higher Educational Institutions in Metro Manila: A DEA Efficiency Measurement

    ERIC Educational Resources Information Center

    de Guzman, Maria Corazon Gwendolyn N.; Cabana, Emilyn

    2009-01-01

    This paper measures the technical efficiency of 16 selected colleges and universities in Metro Manila, Philippines, using academic data for the SY 2001-2005. Using the data envelopment analysis (DEA), on average, schools posted 0.807 index score and need additional 19.3% efficiency growth to be efficient. Overall, there are top four efficient…

  6. Challenging an immediate suspension of a DEA registration: is it time for a new tact?

    PubMed

    Behr, Douglas J

    2014-01-01

    A Drug Enforcement Administration ("DEA") registration is not only a necessity, but also an invaluable commodity for doctors, pharmacists, hospitals and drug wholesalers who prescribe, stock, and distribute controlled substances. While the DEA may only suspend a registration by issuing an immediate suspension order ("ISO) after an ex parte finding of "imminent danger to the public health or safety," the law fails to explicitly protect the registrant by way of a post-suspension hearing on the ISO, despite the registrant's constitutionally protected property interest in the registration. A registrant has only two procedural options--which are often unsuccessful--to challenge the ISO: endure a long and arduous administrative review proceeding or petition the court for a "not-so-easily proven" injunction, all the while the suspension remains in effect and the controlled substance business operations cease. Accordingly, a suspension of the registration may be certain death to doctors and pharmacists without the financial means to operate the business in the absence of the registration. Because the DEA registration is a constitutionally-protected interest, there is a better way to challenge the suspension. The Supreme Court has held that once a license is issued, the continued possession of it is essential to the registrant's livelihood. Therefore suspension or revocation of such a protected interest requires due process. Due-process hearings, while varied, will provide the necessary avenues of review to provide a fair review of the justification of the suspension and its continuance, i.e., whether there truly is imminent danger to public health or safety and whether the suspension is overbroad and should be limited. To date, this thesis remains to be tested and awaits a petitioner with a justiciable claim and the financial resources to challenge the DEA in court. But in the field of DEA ISO challenges, it is time for a new tact!

  7. EpiDEA: extracting structured epilepsy and seizure information from patient discharge summaries for cohort identification.

    PubMed

    Cui, Licong; Bozorgi, Alireza; Lhatoo, Samden D; Zhang, Guo-Qiang; Sahoo, Satya S

    2012-01-01

    Sudden Unexpected Death in Epilepsy (SUDEP) is a poorly understood phenomenon. Patient cohorts to power statistical studies in SUDEP need to be drawn from multiple centers due to the low rate of reported SUDEP incidences. But the current practice of manual chart review of Epilepsy Monitoring Units (EMU) patient discharge summaries is time-consuming, tedious, and not scalable for large studies. To address this challenge in the multi-center NIH-funded Prevention and Risk Identification of SUDEP Mortality (PRISM) Project, we have developed the Epilepsy Data Extraction and Annotation (EpiDEA) system for effective processing of discharge summaries. EpiDEA uses a novel Epilepsy and Seizure Ontology (EpSO), which has been developed based on the International League Against Epilepsy (ILAE) classification system, as the core knowledge resource. By extending the cTAKES natural language processing tool developed at the Mayo Clinic, EpiDEA implements specialized functions to address the unique challenges of processing epilepsy and seizure-related clinical free text in discharge summaries. The EpiDEA system was evaluated on a corpus of 104 discharge summaries from the University Hospitals Case Medical Center EMU and achieved an overall precision of 93.59% and recall of 84.01% with an F-measure of 88.53%. The results were compared against a gold standard created by two epileptologists. We demonstrate the use of EpiDEA for cohort identification through use of an intuitive visual query interface that can be directly used by clinical researchers.

  8. 6000 tpd SRC-I Demonstration Plant gas systems. Design baseline package, Volume 8. [DEA process

    SciTech Connect

    Not Available

    1983-01-27

    Volume 8 contains the design of the fuel gas desulfurization process (DEA) and of the liquefied petroleum gases (LPG) section of the plant. The removal of acid gases is accomplished by intimately contacting the feed stream with the descending DEA solution. A partially regenerated semi-lean DEA solution is fed to an intermediate tray of the column for the bulk removal of H/sub 2/S and CO/sub 2/ while a fully regenerated lean DEA solution is fed at the top tray for the removal of the remaining acid gases in the top section of the absorber. The lean solution stream temperature is maintained at 10 to 15/sup 0/F above the absorber feed gas temperature to prevent hydrocarbon condensation in the column with consequent foaming and flooding of the column. The overhead gas (Stream 6305) leaving the H.P. DEA absorber is cooled and passed through the Sweet Gas K.O. Drum (bottom section of V-15305) to separate any condensate. The gas leaving the drum is further contacted with a 3 weight percent caustic solution in the bottom section of the Treated Gas Wash Column (T-15303) for removal of residual acid gases in order to comply with the sweet gas specifications of 1 ppMv H/sub 2/S and 10 ppMv CO/sub 2/. The LPG Recovery Unit is designed to process 15.95 MMSCFD of low pressure fuel reject gas from the HPU to recover approximately 60 percent of the propane and most of the heavier hydrocarbons. The recovered hydrocarbons are produced as liquefied petroleum gas (LPG) product. Specifications for the LPG product are: (1) Ethane/Propane (Vol/Vol) 0.02; and (2) LPG product should meet GPA Publication 2140-77 Commercial B-P mixture specifications.

  9. Second-Site Suppression of RNase E Essentiality by Mutation of the deaD RNA Helicase in Escherichia coli

    PubMed Central

    Tamura, Masaru; Kers, Johan A.

    2012-01-01

    Escherichia coli cells normally require RNase E activity to propagate and form colonies. Using random Tn10 insertion mutagenesis, we screened for second-site suppressor mutations that restore colony-forming ability (CFA) to E. coli cells lacking RNase E function and found mutations in three separate chromosomal loci that had this phenotype. Restoration of CFA by mutations in two of the genes identified was observed only in nutrient-poor medium, whereas the effects of mutation of the ATP-dependent RNA helicase DeaD were medium independent. Suppression of the rne mutant phenotype by inactivation of deaD was partial, as rne deaD doubly mutant bacteria had a greatly prolonged generation time and grew as filamentous chains in liquid medium. Moreover, we found that CFA restoration by deaD inactivation requires normal expression of the endogenous rng gene in doubly mutant rne deaD cells. Second-site suppression by deaD mutation was attributable specifically to ablation of the helicase activity of DeaD and was reversed by adventitious expression of RhlE or RNase R, both of which can unwind double-stranded RNA. Our results suggest a previously unsuspected role for RNA secondary structure as a determinant of RNase E essentiality. PMID:22328678

  10. Downeast anemia (dea), a new mouse model of severe nonspherocytic hemolytic anemia caused by hexokinase (HK(1)) deficiency.

    PubMed

    Peters, L L; Lane, P W; Andersen, S G; Gwynn, B; Barker, J E; Beutler, E

    2001-01-01

    A new spontaneous mutation in the A/J inbred mouse strain, downeast anemia (dea), causes severe hemolytic anemia with extensive tissue iron deposition and marked reticulocytosis. The anemia is present at birth and persists throughout life. The defect is inherited as an autosomal recessive and is transferable through bone marrow stem cells. The red cell morphology is consistent with a nonspherocytic hemolytic anemia, suggestive of a red cell enzymopathy. In linkage analysis, dea is nonrecombinant with the hexokinase-1 gene (Hk1) on mouse Chromosome 10. Expression of Hk1 is markedly decreased in dea erythroid tissues, and the transcript produced is larger than normal. Hexokinase enzyme activity is significantly decreased in dea tissues, including red cells, spleen, and kidney. Southern blot analyses revealed approximately 5.5 kb of additional sequence in the 5' portion of the dea Hk1 gene, which was identified by direct sequencing as an early transposon (ETn) insertion in intron 4. ETn insertions disrupt genes in several mouse models by a variety of mechanisms, including aberrant splicing of ETn sequences into the mRNA. We conclude that the primary gene defect in the dea mutation is in Hk1 and that dea is a model of generalized hexokinase deficiency, the first such model identified to date.

  11. Evolution of Yield Stress during Structural Relaxation for the Epoxy 828DEA

    NASA Astrophysics Data System (ADS)

    Arechederra, Gabriel; McCoy, John; Kropka, Jamie

    The evolution of yield stress from structural relaxation of diethanolamine cured diglycidyl ether of bisphenol-A, 828DEA, was tracked using uniaxial compression experiments. Samples were aged isothermally for up to 3 months at 5 temperatures ranging from deep in the glass to above Tg. Since 828DEA has remaining reactive potential, it is anticipated that the Tg will continue to evolve throughout the course of the study as new chemical crosslinks are formed. Consequently, it is important to track the evolution of Tg as well as the progression of the fictive temperature in order to interpret the evolution of yield stress. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE.

  12. Multi Laser Pulse Investigation of the DEAS Concept in Hypersonic Flow

    NASA Astrophysics Data System (ADS)

    Minucci, M. A. S.; Toro, P. G. P.; Oliveira, A. C.; Chanes, J. B.; Ramos, A. G.; Nagamatsu, H. T.; Myrabo, L. N.

    2004-03-01

    The present paper presents recent experimental results on the Laser-Supported Directed Energy ``Air Spike'' - DEAS in hypersonic flow achieved by the Laboratory of Aerothermodynamics and Hypersonics - LAH, Brazil. Two CO2 TEA lasers, sharing the same optical cavity, have been used in conjunction with the IEAv 0.3m Hypersonic Shock Tunnel - HST to demonstrate the Laser-Supported DEAS concept. A single and double laser pulse, generated during the tunnel useful test time, were focused through a NaCl lens upstream of a Double Apollo Disc model fitted with seven piezoelectric pressure transducers and six platinum thin film heat transfer gauges. The objective being to corroborate previous results as well as to obtain additional pressure and heat flux distributions information when two laser pulses are used.

  13. Improved actuation strain of PDMS-based DEA materials chemically modified with softening agents

    NASA Astrophysics Data System (ADS)

    Biedermann, Miriam; Blümke, Martin; Wegener, Michael; Krüger, Hartmut

    2015-04-01

    Dielectric elastomer actuators (DEAs) are smart materials that gained much in interest particularly in recent years. One active field of research is the improvement of their properties by modification of their structural framework. The object of this work is to improve the actuation properties of polydimethylsiloxane (PDMS)-based DEAs by covalent incorporation of mono-vinyl-terminated low-molecular PDMS chains into the PDMS network. These low-molecular units act as a kind of softener within the PDMS network. The loose chain ends interfere with the network formation and lower the network's density. PDMS films with up to 50wt% of low-molecular PDMS additives were manufactured and the chemical, mechanical, electrical, and electromechanical properties of these novel materials were investigated.

  14. Measuring health indicators and allocating health resources: a DEA-based approach.

    PubMed

    Yang, Chih-Ching

    2016-02-03

    This paper suggests new empirical DEA models for the measurement of health indicators and the allocation of health resources. The proposed models were developed by first suggesting a population-based health indicator. By introducing the suggested indicator into DEA models, a new approach that solves the problem of health resource allocation has been developed. The proposed models are applied to an empirical study of Taiwan's health system. Empirical findings show that the suggested indicator can successfully accommodate the differences in health resource demands between populations, providing more reliable performance information than traditional indicators such as physician density. Using our models and a commonly used allocation mechanism, capitation, to allocate medical expenditures, it is found that the proposed model always obtains higher performance than those derived from capitation, and the superiority increases as allocated expenditures rise.

  15. Magnetic field observations on DE-A and -B. [Dynamics Explorer A and B satellites

    NASA Technical Reports Server (NTRS)

    Farthing, W. H.; Sugiura, M.; Ledley, B. G.; Cahill, L. J., Jr.

    1981-01-01

    Magnetic field observations are conducted on each of the DE-A and -B satellites by a triaxial fluxgate magnetometer. In the basic mode the instrumental resolution is + or - 1.5 nT; in addition, the DE-A magnetometer has two modes of higher resolution: + or - 0.25 nT and + or - 20 pT. The sampling rate is 16 vector samples per second in all modes. The experiment objectives include observations of field-aligned currents, magnetospheric equatorial currents, and ULF waves. These observations, taking full advantage of the specifically selected orbits of the two spacecraft and of the unique combination of instruments, are performed to achieve a better understanding of the electrodynamic coupling within the atmosphere-ionosphere-magnetosphere system and of wave-particle interactions which contribute to the coupling processes.

  16. A framework for performance measurement in university using extended network data envelopment analysis (DEA) structures

    NASA Astrophysics Data System (ADS)

    Kashim, Rosmaini; Kasim, Maznah Mat; Rahman, Rosshairy Abd

    2015-12-01

    Measuring university performance is essential for efficient allocation and utilization of educational resources. In most of the previous studies, performance measurement in universities emphasized the operational efficiency and resource utilization without investigating the university's ability to fulfill the needs of its stakeholders and society. Therefore, assessment of the performance of university should be separated into two stages namely efficiency and effectiveness. In conventional DEA analysis, a decision making unit (DMU) or in this context, a university is generally treated as a black-box which ignores the operation and interdependence of the internal processes. When this happens, the results obtained would be misleading. Thus, this paper suggest an alternative framework for measuring the overall performance of a university by incorporating both efficiency and effectiveness and applies network DEA model. The network DEA models are recommended because this approach takes into account the interrelationship between the processes of efficiency and effectiveness in the system. This framework also focuses on the university structure which is expanded from the hierarchical to form a series of horizontal relationship between subordinate units by assuming both intermediate unit and its subordinate units can generate output(s). Three conceptual models are proposed to evaluate the performance of a university. An efficiency model is developed at the first stage by using hierarchical network model. It is followed by an effectiveness model which take output(s) from the hierarchical structure at the first stage as a input(s) at the second stage. As a result, a new overall performance model is proposed by combining both efficiency and effectiveness models. Thus, once this overall model is realized and utilized, the university's top management can determine the overall performance of each unit more accurately and systematically. Besides that, the result from the network

  17. A mixed integer bi-level DEA model for bank branch performance evaluation by Stackelberg approach

    NASA Astrophysics Data System (ADS)

    Shafiee, Morteza; Lotfi, Farhad Hosseinzadeh; Saleh, Hilda; Ghaderi, Mehdi

    2016-11-01

    One of the most complicated decision making problems for managers is the evaluation of bank performance, which involves various criteria. There are many studies about bank efficiency evaluation by network DEA in the literature review. These studies do not focus on multi-level network. Wu (Eur J Oper Res 207:856-864, 2010) proposed a bi-level structure for cost efficiency at the first time. In this model, multi-level programming and cost efficiency were used. He used a nonlinear programming to solve the model. In this paper, we have focused on multi-level structure and proposed a bi-level DEA model. We then used a liner programming to solve our model. In other hand, we significantly improved the way to achieve the optimum solution in comparison with the work by Wu (2010) by converting the NP-hard nonlinear programing into a mixed integer linear programming. This study uses a bi-level programming data envelopment analysis model that embodies internal structure with Stackelberg-game relationships to evaluate the performance of banking chain. The perspective of decentralized decisions is taken in this paper to cope with complex interactions in banking chain. The results derived from bi-level programming DEA can provide valuable insights and detailed information for managers to help them evaluate the performance of the banking chain as a whole using Stackelberg-game relationships. Finally, this model was applied in the Iranian bank to evaluate cost efficiency.

  18. Derivation of a No-Significant-Risk-Level (NSRL) for diethanolamine (DEA).

    PubMed

    Wang, Bingxuan; Amacher, David E; Whittaker, Margaret H

    2014-02-01

    Diethanolamine (DEA) has been listed on the State of California's Proposition 65 List. This listing is based in part on tumors reported in a National Toxicology Program (NTP) 2-year dermal carcinogenicity study in mice which found clear evidence of carcinogenic activity in B6C3F₁ mice based on increased incidences of liver neoplasms in both sexes, and increased incidences of renal tubule neoplasms in males. Although considerable controversy exists on the relevance of the NTP study to humans, industries are obligated to comply with the Proposition 65 labeling requirement and drinking water discharge prohibition, unless they are able to demonstrate that DEA levels in their products are below a specific No Significant Risk Level (NSRL). The State of California has not published an NSRL for DEA. In this article, a NSRL of 5.6 μg/day and a life-stage-adjusted NSRL(adj) of 1.4 μg/day are derived from the NTP carcinogenicity study using a benchmark dose modeling method based on the incidence of hepatocellular carcinomas in female mice, in accordance with the guidelines of California EPA.

  19. Curing kinetics of visible light curing dental resin composites investigated by dielectric analysis (DEA).

    PubMed

    Steinhaus, Johannes; Hausnerova, Berenika; Haenel, Thomas; Großgarten, Mandy; Möginger, Bernhard

    2014-03-01

    During the curing process of light curing dental composites the mobility of molecules and molecule segments is reduced leading to a significant increase of the viscosity as well as the ion viscosity. Thus, the kinetics of the curing behavior of 6 different composites was derived from dielectric analysis (DEA) using especially redesigned flat sensors with interdigit comb electrodes allowing for irradiation at the top side and measuring the ion viscosity at the bottom side. As the ion viscosities of dental composites change 1-3 orders of magnitude during the curing process, DEA provides a sensitive approach to evaluate their curing behavior, especially in the phase of undisturbed chain growth. In order to determine quantitative kinetic parameters a kinetic model is presented and examined for the evaluation of the ion viscosity curves. From the obtained results it is seen that DEA might be employed in the investigation of the primary curing process, the quality assurance of ingredients as well as the control of processing stability of the light curing dental composites.

  20. Benchmarking road safety of U.S. states: a DEA-based Malmquist productivity index approach.

    PubMed

    Egilmez, Gokhan; McAvoy, Deborah

    2013-04-01

    In this study, a DEA based Malmquist index model was developed to assess the relative efficiency and productivity of U.S. states in decreasing the number of road fatalities. Even though the national trend in fatal crashes has reached to the lowest level since 1949 (Traffic Safety Annual Assessment Highlights, 2010), a state-by-state analysis and comparison has not been studied considering other characteristics of the holistic national road safety assessment problem in any work in the literature or organizational reports. In this study, a DEA based Malmquist index model was developed to assess the relative efficiency and productivity of 50 U.S. states in reducing the number of fatal crashes. The single output, fatal crashes, and five inputs were aggregated into single road safety score and utilized in the DEA-based Malmquist index mathematical model. The period of 2002-2008 was considered due to data availability for the inputs and the output considered. According to the results, there is a slight negative productivity (an average of -0.2 percent productivity) observed in the U.S. on minimizing the number of fatal crashes along with an average of 2.1 percent efficiency decline and 1.8 percent technological improvement. The productivity in reducing the fatal crashes can only be attributed to the technological growth since there is a negative efficiency growth is occurred. It can be concluded that even though there is a declining trend observed in the fatality rates, the efficiency of states in utilizing societal and economical resources towards the goal of zero fatality is not still efficient. More effective policy making towards increasing safety belt usage and better utilization of safety expenditures to improve road condition are derived as the key areas to focus on for state highway safety agencies from the scope of current research.

  1. I-deas TMG to NX Space Systems Thermal Model Conversion and Computational Performance Comparison

    NASA Technical Reports Server (NTRS)

    Somawardhana, Ruwan

    2011-01-01

    CAD/CAE packages change on a continuous basis as the power of the tools increase to meet demands. End -users must adapt to new products as they come to market and replace legacy packages. CAE modeling has continued to evolve and is constantly becoming more detailed and complex. Though this comes at the cost of increased computing requirements Parallel processing coupled with appropriate hardware can minimize computation time. Users of Maya Thermal Model Generator (TMG) are faced with transitioning from NX I -deas to NX Space Systems Thermal (SST). It is important to understand what differences there are when changing software packages We are looking for consistency in results.

  2. Evaluating the efficiency of municipalities in collecting and processing municipal solid waste: a shared input DEA-model.

    PubMed

    Rogge, Nicky; De Jaeger, Simon

    2012-10-01

    This paper proposed an adjusted "shared-input" version of the popular efficiency measurement technique Data Envelopment Analysis (DEA) that enables evaluating municipality waste collection and processing performances in settings in which one input (waste costs) is shared among treatment efforts of multiple municipal solid waste fractions. The main advantage of this version of DEA is that it not only provides an estimate of the municipalities overall cost efficiency but also estimates of the municipalities' cost efficiency in the treatment of the different fractions of municipal solid waste (MSW). To illustrate the practical usefulness of the shared input DEA-model, we apply the model to data on 293 municipalities in Flanders, Belgium, for the year 2008.

  3. Equilibrium solubilities of CO/sub 2/ and H/sub 2/S in diethanolamine (DEA) and methyldiethanolamine (MDEA) solutions

    SciTech Connect

    Ho, A.S.; Equren, P.R. )

    1988-01-01

    The ability to predict equilibrium phase behavior in systems containing CO/sub 2/ and/or H/sub 2/S in alkanolamine solutions such as diethanolamine (DEA) and methyldiethanolamine (MDEA) is of vital importance for proper design and operation of acid gases treating systems. Literature data for the solubilities of CO/sub 2/ and/or H/sub 2/S in DEA and MDEA systems have been compiled and evaluated. Experimental measurements have also been made to confirm literature data and to expand the data base. A vapor-liquid equilibrium (VLE) model similar to the one developed by Kent and Eisenberg has been developed to correlate the data. The model gives the most accurate predictions when compared to other VLE models available for predicting equilibrium acid gas partial pressures over DEA and MDEA solutions.

  4. AGS experiments - 1994, 1995, 1996

    SciTech Connect

    Depken, J.C.

    1997-01-01

    This report contains the following information on the Brookhaven AGS Accelerator complex: FY 1996 AGS schedule as run; FY 1997 AGS schedule (working copy); AGS beams 1997; AGS experimental area FY 1994 physics program; AGS experimental area FY 1995 physics program; AGS experimental area FY 1996 physics program; AGS experimental area FY 1997 physics program (in progress); a listing of experiments by number; two-phage summaries of each experiment begin here, also ordered by number; listing of publications of AGS experiments begins here; and listing of AGS experimenters begins here.

  5. Non-ionic, thermo-responsive DEA/DMA nanogels: synthesis, characterization, and use for DNA separations by microchip electrophoresis.

    PubMed

    Lu, Xihua; Sun, Mingyun; Barron, Annelise E

    2011-05-15

    Thermo-responsive polymer "nanogels" (crosslinked hydrogel particles with sub-100 nm diameters) are intriguing for many potential applications in biotechnology and medicine. There have been relatively few reports of electrostatically neutral, thermosensitive nanogels comprising a high fraction of hydrophilic co-monomer. Here we demonstrate the syntheses and characterization of novel, non-ionic nanogels based on random N,N-diethylacrylamide (DEA)/N,N-dimethylacrylamide (DMA) copolymers, made by free-radical, surfactant-free dispersion polymerization. The volume-phase transition temperatures of these DEA/DMA nanogels are strongly affected by co-monomer composition, providing a way to "tune" the phase transition temperature of these non-ionic nanogels. While DEA nanogels (comprising no DMA) can be obtained at 70 °C by standard emulsion precipitation, DEA/DMA random co-polymer nanogels can be obtained only in a particular range of temperatures, above the initial phase transition temperature and below the critical precipitation temperature of the DEA/DMA copolymer, controlled by co-monomer composition. Increasing percentages of DMA in the nanogels raises the phase transition temperature, and attenuates and broadens it as well. We find that concentrated DEA/DMA nanogel dispersions are optically clear at room temperature. This good optical clarity was exploited for their use in a novel DNA sieving matrix for microfluidic chip electrophoresis. An ultrafast, high-efficiency dsDNA separation was achieved in less than 120 s for dsDNA ranging from 75 bp to 15,000 bp.

  6. Brazilian Activities On The Laser-Supported DEAS In Hypersonic Flow

    NASA Astrophysics Data System (ADS)

    Minucci, M. A. S.; Toro, P. G. P.; Chanes, J. B.; Ramos, A. G.; Pereira, A. L.; Nagamatsu, H. T.; Myrabo, L. N.

    2003-05-01

    The present paper presents recent (original) and previous experimental results on the Laser-Supported Directed Energy ``Air Spike'' - DEAS in hypersonic flow achieved by the Laboratory of Aerothermodynamics and Hypersonics - LAH, Brazil. A CO2 TEA laser has been used in conjunction with the IEAv 0.3m Hypersonic Shock Tunnel - HST to demonstrate the Laser-Supported DEAS concept. A single laser pulse generated during the tunnel useful test time was focused through a NaCl lens ahead of an aluminum hemisphere-cylinder model fitted with a piezoelectric pressure transducer at the stagnation point. In the more recent experiments, the simple hemisphere-cylinder model was substituted by a Double Apollo Disc model fitted with seven piezoelectric pressure transducers and six platinum thin film heat transfer gauges. The objective being to corroborate the past results as well as to obtain additional pressure distribution information and new heat transfer data.

  7. Method for selection of optimal road safety composite index with examples from DEA and TOPSIS method.

    PubMed

    Rosić, Miroslav; Pešić, Dalibor; Kukić, Dragoslav; Antić, Boris; Božović, Milan

    2017-01-01

    Concept of composite road safety index is a popular and relatively new concept among road safety experts around the world. As there is a constant need for comparison among different units (countries, municipalities, roads, etc.) there is need to choose an adequate method which will make comparison fair to all compared units. Usually comparisons using one specific indicator (parameter which describes safety or unsafety) can end up with totally different ranking of compared units which is quite complicated for decision maker to determine "real best performers". Need for composite road safety index is becoming dominant since road safety presents a complex system where more and more indicators are constantly being developed to describe it. Among wide variety of models and developed composite indexes, a decision maker can come to even bigger dilemma than choosing one adequate risk measure. As DEA and TOPSIS are well-known mathematical models and have recently been increasingly used for risk evaluation in road safety, we used efficiencies (composite indexes) obtained by different models, based on DEA and TOPSIS, to present PROMETHEE-RS model for selection of optimal method for composite index. Method for selection of optimal composite index is based on three parameters (average correlation, average rank variation and average cluster variation) inserted into a PROMETHEE MCDM method in order to choose the optimal one. The model is tested by comparing 27 police departments in Serbia.

  8. New DEA materials by organic modification of silicone and polyurethane networks

    NASA Astrophysics Data System (ADS)

    Kussmaul, Björn; Risse, Sebastian; Wegener, Michael; Bluemke, Martin; Krause, Jens; Wagner, Joachim; Feller, Torsten; Clauberg, Karin; Hitzbleck, Julia; Gerhard, Reimund; Krueger, Hartmut

    2013-04-01

    Dielectric elastomer actuators (DEAs) can be optimized by modifying the dielectric or mechanical properties of the electroactive polymer. In this work both properties were improved simultaneously by a simple process, the one-step film formation for polyurethane and silicone films. The silicone network contains polydimethylsiloxane (PDMS) chains, as well as cross-linker and grafted molecular dipoles in varying amounts. The process leads to films, which are homogenous down to the molecular level and show higher permittivities as well as reduced stiffnesses. The dipole modification of a new silicone leads to 40 times higher sensitivities, compared to the unmodified films. This new material reaches the sensitivity of the widely used acrylate elatomer VHB4905. A similar silicone modification was obtained by using smart fillers consisting of organic dipoles and additional groups realizing a high compatibility to the silicon network. Polyurethanes are alternative elastomers for DEAs which are compared with the silicones in important properties. Polyurethanes have an intrinsically high dielectric constant (above 7), which is based on the polar nature of the polyurethane fragments. Polyurethanes can be made in roll-to-roll process giving constant mechanical and electrical properties on a high level.

  9. Eco-efficiency analysis of Spanish WWTPs using the LCA + DEA method.

    PubMed

    Lorenzo-Toja, Yago; Vázquez-Rowe, Ian; Chenel, Sergio; Marín-Navarro, Desirée; Moreira, María Teresa; Feijoo, Gumersindo

    2015-01-01

    Wastewater treatment plants (WWTPs) are regarded as units designed for the efficient removal of organic matter and nutrients from polluted wastewaters, avoiding their discharge into the environment. Despite these benefits, they have also been found to be highly energy intensive, with consequent increased emissions in terms of greenhouse gases and other environmental impacts. Therefore, it has become imperative to monitor thoroughly the overall functioning of WWTPs from an integrated perspective with the aim of understanding how these can improve their eco-efficiency. In this case study, a group of 113 WWTPs located in regions across Spain were analysed using the methodology that combines life cycle assessment (LCA) and data envelopment analysis (DEA). The aim of this work was to determine the operational efficiency of each unit in order to obtain environmental benchmarks for inefficient plants. Thereafter, the environmental gains linked with the inputs reduction proposed for the DEA model for each unit were computed in order to verify eco-efficiency criteria. The operational complexity of WWTPs resulted in several identified factors affecting their efficiency which are discussed in depth, including the size of the facility, the climatic influence, the influent load and the over- or underuse of the plant.

  10. DEA for soft robotics: 1-gram actuator picks up a 60-gram egg

    NASA Astrophysics Data System (ADS)

    Shintake, Jun; Rosset, Samuel; Schubert, Bryan; Mintchev, Stefano; Floreano, Dario; Shea, Herbert

    2015-04-01

    We introduce a soft actuator for grippers using DEA capable of bending actuation. The actuator is also able to generate the electro-adhesion by the fringe field formed at the edges of the electrodes. The adhesion improves the holding force and ensures the conformation of the structure to the object. After the characterization of the actuator, we develop a 2-finger soft gripper capable of holding various objects. The gripper has a mass of around 1 g, and consists of a few cm long actuation parts, realizing simple open-close movement. The compliance of the gripper leads to conformation of the structure against the object surface, which is proven by successful handling of objects with different geometries such as a toothbrush, a flat paper, and a ping pong ball. The effect of the electro-adhesion is visible when the paper is held with its flat shape meaning that an adhesion force against gravity exists. Also, by the fact that the conformed structure increases the contact area, the holding force is improved while avoiding damaging the object, which is highlighted by the ability to hold a raw egg weighing around 60 g. This soft gripper, combining both actuation and electro-adhesion, illustrates the potential use of DEA for soft robotics.

  11. Technology Efficiency Study on Nuclear Power and Coal Power in Guangdong Province Based on DEA

    SciTech Connect

    Yinong Li; Dong Wang

    2006-07-01

    Guangdong Province has taken the lead in embarking on nuclear power development to resolve its dire lack of primary resources. With the deepening of the on-going structural reform in the electric power sector in China, the market competition scheme is putting electricity generation enterprises under severe strain. Consequently, it is incumbent upon the nuclear power producers to steadily upgrade management, enhance technical capabilities, reduce cost and improve efficiency. At present, gradual application of such efficiency evaluation methodology has already commenced in some sectors in China including the electric power industry. The purpose of this paper is to use the Data Envelopment Analysis (DEA), which is a cutting-edge approach in the efficiency evaluation field - to study the technological efficiency between nuclear power and coal power in Guangdong Province. The DEA results demonstrate that, as far as Guangdong Province is concerned, the technological efficiency of nuclear power is higher than that of coal power in terms of Technological Efficiency (TE), Pure Technology Efficiency (PTE) and Scale Efficiency (SE). The reason is that nuclear power technology is advanced with a much higher equipment availability factor. Under the same scale, the generation output of nuclear power is far higher than that of equivalent coal power generation. With the environmental protection and sustainable development requirements taken into full account, nuclear power constitutes a clean, safe and highly-efficient energy form which should be extensively harnessed in Guangdong Province to fuel its future continuing economic growth. (authors)

  12. The assessment of vulnerability to natural disasters in China by using the DEA method

    SciTech Connect

    Wei Yiming; Fan Ying; Lu Cong; Tsai, H.-T

    2004-05-01

    China has been greatly affected by natural disasters, so that it is of great importance to analyze the impact of natural disasters on national economy. Usually, the frequency of disasters or absolute loss inflicted by disasters is the first priority to be considered, while the capability of regions to overcome disasters is ignored. The concept of vulnerability is used to measure the capability to overcome disasters in different regions with distinctive economies. Traditional methods for vulnerability analysis calculate sub-indices based on disaster frequency, loss, the economic impact and the population of each region, and then add the sub-indices to get a composite index for regional vulnerability. But those methods are sensitive to the weights selected for sub-indices when multi-indexes are added up to get an index of total vulnerability. The analytic results are less convincing because of the subjectivity of different weighting methods. A data envelopment analysis (DEA)-based model for analysis of regional vulnerability to natural disasters is presented here to improve upon the traditional method. This paper systematically describes the DEA method to evaluate the relative severity of disasters in each region. A model for regional vulnerability analysis is developed, based on the annual governmental statistics from 1989 to 2000. The regional vulnerabilities in China's mainland are illustrated as a case study, and a new method for the classification of regional vulnerability to natural disasters in China is proposed.

  13. Technical evaluation of hybrid membrane/DEA modeling. Topical report, January 1990-August 1990

    SciTech Connect

    Changela, M.K.; McKee, R.L.; Reading, G.J.

    1991-08-01

    The report examines the potential for cost and/or performance advantages of a hybrid system, the integration of membranes and amines, over a single-stage membrane or amine system for producing pipeline quality gas on a small scale from high carbon dioxide subquality natural gas. The hybrid configuration evaluated is a membrane system in series with a conventional diethanolamine (DEA) system. Comparison of the established costs shows that each system has a region of operability. Membranes offer higher cost savings at low feed flow rates and high carbon dioxide feed contents. The hybrid system offers cost savings over moderate to high feed flow rates and for moderate to high carbon dioxide feed contents. The DEA system offers cost savings for moderate to high feed flow rates at low to moderate carbon dioxide feed contents. Membranes do not exhibit economies of scale which works to their advantage for removing carbon dioxide on a small scale. Processing costs for amine systems are more sensitive to economies of scale, and thus decrease more rapidly than for membranes at higher feed flow rates. The hybrid system offers cost savings in regions that have been perceived as exclusively amine treating applications, thus increasing the area of operability for membranes.

  14. Enhanced DEA model with undesirable output and interval data for rice growing farmers performance assessment

    NASA Astrophysics Data System (ADS)

    Khan, Sahubar Ali Mohd. Nadhar; Ramli, Razamin; Baten, M. D. Azizul

    2015-12-01

    Agricultural production process typically produces two types of outputs which are economic desirable as well as environmentally undesirable outputs (such as greenhouse gas emission, nitrate leaching, effects to human and organisms and water pollution). In efficiency analysis, this undesirable outputs cannot be ignored and need to be included in order to obtain the actual estimation of firms efficiency. Additionally, climatic factors as well as data uncertainty can significantly affect the efficiency analysis. There are a number of approaches that has been proposed in DEA literature to account for undesirable outputs. Many researchers has pointed that directional distance function (DDF) approach is the best as it allows for simultaneous increase in desirable outputs and reduction of undesirable outputs. Additionally, it has been found that interval data approach is the most suitable to account for data uncertainty as it is much simpler to model and need less information regarding its distribution and membership function. In this paper, an enhanced DEA model based on DDF approach that considers undesirable outputs as well as climatic factors and interval data is proposed. This model will be used to determine the efficiency of rice farmers who produces undesirable outputs and operates under uncertainty. It is hoped that the proposed model will provide a better estimate of rice farmers' efficiency.

  15. Enhanced DEA model with undesirable output and interval data for rice growing farmers performance assessment

    SciTech Connect

    Khan, Sahubar Ali Mohd. Nadhar Ramli, Razamin Baten, M. D. Azizul

    2015-12-11

    Agricultural production process typically produces two types of outputs which are economic desirable as well as environmentally undesirable outputs (such as greenhouse gas emission, nitrate leaching, effects to human and organisms and water pollution). In efficiency analysis, this undesirable outputs cannot be ignored and need to be included in order to obtain the actual estimation of firms efficiency. Additionally, climatic factors as well as data uncertainty can significantly affect the efficiency analysis. There are a number of approaches that has been proposed in DEA literature to account for undesirable outputs. Many researchers has pointed that directional distance function (DDF) approach is the best as it allows for simultaneous increase in desirable outputs and reduction of undesirable outputs. Additionally, it has been found that interval data approach is the most suitable to account for data uncertainty as it is much simpler to model and need less information regarding its distribution and membership function. In this paper, an enhanced DEA model based on DDF approach that considers undesirable outputs as well as climatic factors and interval data is proposed. This model will be used to determine the efficiency of rice farmers who produces undesirable outputs and operates under uncertainty. It is hoped that the proposed model will provide a better estimate of rice farmers’ efficiency.

  16. Using a DEA Management Tool through a Nonparametric Approach: An Examination of Urban-Rural Effects on Thai School Efficiency

    ERIC Educational Resources Information Center

    Kantabutra, Sangchan

    2009-01-01

    This paper examines urban-rural effects on public upper-secondary school efficiency in northern Thailand. In the study, efficiency was measured by a nonparametric technique, data envelopment analysis (DEA). Urban-rural effects were examined through a Mann-Whitney nonparametric statistical test. Results indicate that urban schools appear to have…

  17. Measuring the Efficiency of Public Universities: Using Data Envelopment Analysis (DEA) to Examine Public Universities in Saudi Arabia

    ERIC Educational Resources Information Center

    Alabdulmenem, Fahad Mohammed

    2017-01-01

    Saudi Arabia is one of the countries that allot substantial amount of government resources for education. Thus, it is important to measure how these resources are used to generate favorable academic outcomes for its nationals. In this study, data envelopment analysis (DEA) is used to measure the relative efficiency of 25 public universities in…

  18. Employing post-DEA cross-evaluation and cluster analysis in a sample of Greek NHS hospitals.

    PubMed

    Flokou, Angeliki; Kontodimopoulos, Nick; Niakas, Dimitris

    2011-10-01

    To increase Data Envelopment Analysis (DEA) discrimination of efficient Decision Making Units (DMUs), by complementing "self-evaluated" efficiencies with "peer-evaluated" cross-efficiencies and, based on these results, to classify the DMUs using cluster analysis. Healthcare, which is deprived of such studies, was chosen as the study area. The sample consisted of 27 small- to medium-sized (70-500 beds) NHS general hospitals distributed throughout Greece, in areas where they are the sole NHS representatives. DEA was performed on 2005 data collected from the Ministry of Health and the General Secretariat of the National Statistical Service. Three inputs -hospital beds, physicians and other health professionals- and three outputs -case-mix adjusted hospitalized cases, surgeries and outpatient visits- were included in input-oriented, constant-returns-to-scale (CRS) and variable-returns-to-scale (VRS) models. In a second stage (post-DEA), aggressive and benevolent cross-efficiency formulations and clustering were employed, to validate (or not) the initial DEA scores. The "maverick index" was used to sort the peer-appraised hospitals. All analyses were performed using custom-made software. Ten benchmark hospitals were identified by DEA, but using the aggressive and benevolent formulations showed that two and four of them respectively were at the lower end of the maverick index list. On the other hand, only one 100% efficient (self-appraised) hospital was at the higher end of the list, using either formulation. Cluster analysis produced a hierarchical "tree" structure which dichotomized the hospitals in accordance to the cross-evaluation results, and provided insight on the two-dimensional path to improving efficiency. This is, to our awareness, the first study in the healthcare domain to employ both of these post-DEA techniques (cross efficiency and clustering) at the hospital (i.e. micro) level. The potential benefit for decision-makers is the capability to examine high

  19. Residual internal stress optimization for EPON 828/DEA thermoset resin using fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Rohr, Garth D.; Rasberry, Roger D.; Kaczmarowski, Amy K.; Stavig, Mark E.; Gibson, Cory S.; Udd, Eric; Roach, Allen R.; Nation, Brendan

    2015-05-01

    Internal residual stresses and overall mechanical properties of thermoset resins are largely dictated by the curing process. It is well understood that fiber Bragg grating (FBG) sensors can be used to evaluate temperature and cure induced strain while embedded during curing. Herein, is an extension of this work whereby we use FBGs as a probe for minimizing the internal residual stress of an unfilled and filled Epon 828/DEA resin. Variables affecting stress including cure cycle, mold (release), and adhesion promoting additives will be discussed and stress measurements from a strain gauge pop-off test will be used as comparison. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  20. Kinetic study of carbon dioxide absorption into glycine promoted diethanolamine (DEA)

    NASA Astrophysics Data System (ADS)

    Pudjiastuti, Lily; Susianto, Altway, Ali; IC, Maria Hestia; Arsi, Kartika

    2015-12-01

    In industry, especially petrochemical, oil and natural gas industry, required separation process of CO2 gas which is a corrosive gas (acid gas). This characteristic can damage the plant utility and piping systems as well as reducing the caloric value of natural gas. Corrosive characteristic of CO2 will appear in areas where there is a decrease in temperature and pressure, such as at the elbow pipe, tubing, cooler and injector turbine. From disadvantages as described above, then it is important to do separation process in the CO2 gas stream, one of the method for remove CO2 from the gas stream is reactive absorption using alkanolamine based solution with promotor. Therefore, this study is done to determine the kinetics constant of CO2 absorption in diethanolamine (DEA) solution using a glycine promoter. Glycine is chosen as a promoter because glycine is a primary amine compound which is reactive, moreover, glycine has resistance to high temperatures so it will not easy to degradable and suitable for application in industry. The method used in this study is absorption using laboratory scale wetted wall column equipment at atmospheric of pressure. This study will to provide the reaction kinetics data information in order to optimize the separation process of CO2 in the industrialized world. The experimental results show that rising temperatures from 303,15 - 328,15 K and the increase of concentration of glycine from 1% - 3% weight will increase the absorption rate of carbon dioxide in DEA promoted with glycine by 24,2% and 59,764% respectively, also the reaction kinetic constant is 1.419 × 1012 exp (-3634/T) (m3/kmol.s). This result show that the addition of glycine as a promoter can increase absorption rate of carbon dioxide in diethanolamine solution and cover the weaknesses of diethanolamine solution.

  1. AgRISTARS

    NASA Technical Reports Server (NTRS)

    1984-01-01

    An introduction to the overall AgRISTARS program, a general statement on progress, and separate summaries of the activities of each project, with emphasis on the technical highlights are presented. Organizational and management information on AgRISTARS is included in the appendices, as is a complete bibliography of publication and reports.

  2. AGS experiments: 1993 - 1994 - 1995

    SciTech Connect

    Depken, J.C.

    1996-04-01

    This report contains: FY 1995 AGS Schedule as Run; FY 1996-97 AGE Schedule (working copy); AGS Beams 1995; AGS Experimental Area FY 1993 Physics Program; AGS Experimental Area FY 1994 Physics Program; AGS Experimental Area FY 1995 Physics Program; AGS Experimental Area FY 1996 Physics Program (In progress); A listing of experiments by number; Two-page summaries of each experiment begin here, also ordered by number; Listing of publications of AGS experiments begins here; and Listing of AGS experimenters begins here. This is the twelfth edition.

  3. @AuAg nanostructures

    NASA Astrophysics Data System (ADS)

    Singh, Rina; Soni, R. K.

    2014-09-01

    Bimetallic and trimetallic nanoparticles have attracted significant attention in recent times due to their enhanced electrochemical and catalytic properties compared to monometallic nanoparticles. The numerical calculations using Mie theory has been carried out for three-layered metal nanoshell dielectric-metal-metal (DMM) system consisting of a particle with a dielectric core (Al@Al2O3), a middle metal Ag (Au) layer and an outer metal Au (Ag) shell. The results have been interpreted using plasmon hybridization theory. We have also prepared Al@Al2O3@Ag@Au and Al@Al2O3@AgAu triple-layered core-shell or alloy nanostructure by two-step laser ablation method and compared with calculated results. The synthesis involves temporal separations of Al, Ag, and Au deposition for step-by-step formation of triple-layered core-shell structure. To form Al@Ag nanoparticles, we ablated silver for 40 min in aluminium nanoparticle colloidal solution. As aluminium oxidizes easily in water to form alumina, the resulting structure is core-shell Al@Al2O3. The Al@Al2O3 particle acts as a seed for the incoming energetic silver particles for multilayered Al@Al2O3@Ag nanoparticles is formed. The silver target was then replaced by gold target and ablation was carried out for different ablation time using different laser energy for generation of Al@Al2O3@Ag@Au core-shell or Al@Al2O3@AgAu alloy. The formation of core-shell and alloy nanostructure was confirmed by UV-visible spectroscopy. The absorption spectra show shift in plasmon resonance peak of silver to gold in the range 400-520 nm with increasing ablation time suggesting formation of Ag-Au alloy in the presence of alumina particles in the solution.

  4. FEM/SINDA: Combining the strengths of NASTRAN, SINDA, I-DEAS, and PATRAN for thermal and structural analysis

    NASA Technical Reports Server (NTRS)

    Zarda, P. Richard; Anderson, Ted; Baum, Fred

    1993-01-01

    This paper describes the interface/integration between FEM/SINDA, a general purpose geometry driven thermal analysis code, and the FEM software: I-DEAS, PATRAN, and NASTRAN. FEM/SINDA brings together the advantages of the finite element method to model arbitrary geometry and anisotropic materials and SINDA's finite difference capability to model thermal properties, loads, and boundary conditions that vary with time or temperature. I-DEAS and PATRAN thermal entities are directly supported since FEM/SINDA uses the nodes of the FEM model as the point at which the temperature is determined. Output from FEM/SINDA (as well as the FEM/SINDA input deck) can be used directly by NASTRAN for structural analysis.

  5. AgSTAR Partners

    EPA Pesticide Factsheets

    AgSTAR’s Partner Program builds stronger relationships with state and non-governmental stakeholders to support all phases of anaerobic digester projects: planning, deployment, and long-term success.

  6. Effectiveness of maritime safety control in different navigation zones using a spatial sequential DEA model: Yangtze River case.

    PubMed

    Wu, Bing; Wang, Yang; Zhang, Jinfen; Savan, Emanuel Emil; Yan, Xinping

    2015-08-01

    This paper aims to analyze the effectiveness of maritime safety control from the perspective of safety level along the Yangtze River with special considerations for navigational environments. The influencing variables of maritime safety are reviewed, including ship condition, maritime regulatory system, human reliability and navigational environment. Because the former three variables are generally assumed to be of the same level of safety, this paper focuses on studying the impact of navigational environments on the level of safety in different waterways. An improved data envelopment analysis (DEA) model is proposed by treating the navigational environment factors as inputs and ship accident data as outputs. Moreover, because the traditional DEA model cannot provide an overall ranking of different decision making units (DMUs), the spatial sequential frontiers and grey relational analysis are incorporated into the DEA model to facilitate a refined assessment. Based on the empirical study results, the proposed model is able to solve the problem of information missing in the prior models and evaluate the level of safety with a better accuracy. The results of the proposed DEA model are further compared with an evidential reasoning (ER) method, which has been widely used for level of safety evaluations. A sensitivity analysis is also conducted to better understand the relationship between the variation of navigational environments and level of safety. The sensitivity analysis shows that the level of safety varies in terms of traffic flow. It indicates that appropriate traffic control measures should be adopted for different waterways to improve their safety. This paper presents a practical method of conducting maritime level of safety assessments under dynamic navigational environment.

  7. Ag-Al-Ca

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 1 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Ag-Al-Ca' with the content:

  8. Evaluating the efficiency of municipalities in collecting and processing municipal solid waste: A shared input DEA-model

    SciTech Connect

    Rogge, Nicky; De Jaeger, Simon

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Complexity in local waste management calls for more in depth efficiency analysis. Black-Right-Pointing-Pointer Shared-input Data Envelopment Analysis can provide solution. Black-Right-Pointing-Pointer Considerable room for the Flemish municipalities to improve their cost efficiency. - Abstract: This paper proposed an adjusted 'shared-input' version of the popular efficiency measurement technique Data Envelopment Analysis (DEA) that enables evaluating municipality waste collection and processing performances in settings in which one input (waste costs) is shared among treatment efforts of multiple municipal solid waste fractions. The main advantage of this version of DEA is that it not only provides an estimate of the municipalities overall cost efficiency but also estimates of the municipalities' cost efficiency in the treatment of the different fractions of municipal solid waste (MSW). To illustrate the practical usefulness of the shared input DEA-model, we apply the model to data on 293 municipalities in Flanders, Belgium, for the year 2008.

  9. Energy efficiency in Spanish wastewater treatment plants: a non-radial DEA approach.

    PubMed

    Hernández-Sancho, F; Molinos-Senante, M; Sala-Garrido, R

    2011-06-15

    Wastewater treatment plants (WWTPs) are energy-intensive facilities. Thus, reducing their carbon footprint is particularly important, both economically and environmentally. Knowing the real operating energy efficiency of WWTPs is the starting point for any energy-saving initiative. In this article, we applied a non-radial Data Envelopment Analysis (DEA) methodology to calculate energy efficiency indices for sampling of WWTPs located in Spain. In a second stage analysis, we examined the operating variables contributing to differences in energy efficiency among plants. It is verified that energy efficiencies of the analyzed WWTPs were quite low, with only 10% of them being efficient. We found that plant size, quantity of organic matter removed, and type of bioreactor aeration were significant variables in explaining energy efficiency differences. In contrast, age of the plant was not a determining factor in energy consumption. Lastly, we quantified the potential savings, both in economic terms and in terms of CO(2) emissions, that could be expected from an improvement in energy efficiency of WWTPs.

  10. Zipping it up: DEAs independent of the elastomer's electric breakdown field

    NASA Astrophysics Data System (ADS)

    Gebbers, Pit; Grätzel, Chauncey; Maffli, Luc; Stamm, Christoph; Shea, Herbert

    2012-04-01

    We demonstrate here an alternative dielectric elastomer actuator (DEA) structure, which relies on the compliant nature of elastomer membranes but does not require any electric field in the elastomer. Our elastomer zipping device is a macroscopic version of the electrostatic zipping actuators common in silicon MEMS. It consists of a cm-sized metallic bottom electrode, covered by a thin insulator, on which the elastomer membrane is bonded, enclosing a tapered air gap. A compliant electrode is patterned on the lower face of the elastomer membrane. Applying a voltage between solid bottom electrode and compliant electrode leads to controlled pull-in in movement, comparable to the closing of a zipper, thus giving large strokes and forces with no electrical requirements on the elastomer since no voltage is applied across the membrane. The compliant electrodes (20 mm diameter) are produced by metal ion-implantation into the elastomer membranes. The bottom metal electrodes are coated with 10 to 30 μm of Al2O3. We report on our experimental study of membrane deflection and dynamics and discuss the effect of design parameters such as elastomer mechanical properties and actuator geometry. Membrane deflection of up to 1.4 mm was reached at only 200 V actuation voltage. The large membrane deformation achieved with this zipping actuation can be applied to applications such as pumps or tunable liquid lenses. The out-of plane movement of the membrane can be used for linear actuation.

  11. Surface Heat Flux and Pressure Distribution on a Hypersonic Blunt Body With DEAS

    NASA Astrophysics Data System (ADS)

    Salvador, I. I.; Minucci, M. A. S.; Toro, P. G. P.; Oliveira, A. C.; Channes, J. B.

    2008-04-01

    With the currently growing interest for advanced technologies to enable hypersonic flight comes the Direct Energy Air Spike concept, where pulsed beamed laser energy is focused upstream of a blunt flight vehicle to disrupt the flow structure creating a virtual, slender body geometry. This allies in the vehicle both advantages of a blunt body (lower thermal stresses) to that of a slender geometry (lower wave drag). The research conducted at the Henry T. Nagamatsu Laboratory for Aerodynamics and Hypersonics focused on the measurement of the surface pressure and heat transfer rates on a blunt model. The hypersonic flight conditions were simulated at the HTN Laboratory's 0.3 m T2 Hypersonic Shock Tunnel. During the tests, the laser energy was focused upstream the model by an infrared telescope to create the DEAS effect, which was supplied by a TEA CO2 laser. Piezoelectric pressure transducers were used for the pressure measurements and fast response coaxial thermocouples were used for the measurement of surface temperature, which was later used for the estimation of the wall heat transfer using the inverse heat conduction theory.

  12. How efficient are Greek hospitals? A case study using a double bootstrap DEA approach.

    PubMed

    Kounetas, Kostas; Papathanassopoulos, Fotis

    2013-12-01

    The purpose of this study was to measure Greek hospital performance using different input-output combinations, and to identify the factors that influence their efficiency thus providing policy makers with valuable input for the decision-making process. Using a unique dataset, we estimated the productive efficiency of each hospital through a bootstrapped data envelopment analysis (DEA) approach. In a second stage, we explored, using a bootstrapped truncated regression, the impact of environmental factors on hospitals' technical and scale efficiency. Our results reveal that over 80% of the examined hospitals appear to have a technical efficiency lower than 0.8, while the majority appear to be scale efficient. Moreover, efficiency performance differed with inclusion of medical examinations as an additional variable. On the other hand, bed occupancy ratio appeared to affect both technical and scale efficiency in a rather interesting way, while the adoption of advanced medical equipment and the type of hospital improves scale and technical efficiency, correspondingly. The findings of this study on Greek hospitals' performance are not encouraging. Furthermore, our results raise questions regarding the number of hospitals that should operate, and which type of hospital is more efficient. Finally, the results indicate the role of medical equipment in performance, confirming its misallocation in healthcare expenditure.

  13. The RNA Helicase DeaD Stimulates ExsA Translation To Promote Expression of the Pseudomonas aeruginosa Type III Secretion System

    PubMed Central

    Intile, Peter J.; Balzer, Grant J.; Wolfgang, Matthew C.

    2015-01-01

    ABSTRACT The Pseudomonas aeruginosa type III secretion system (T3SS) is a primary virulence factor important for phagocytic avoidance, disruption of host cell signaling, and host cell cytotoxicity. ExsA is the master regulator of T3SS transcription. The expression, synthesis, and activity of ExsA is tightly regulated by both intrinsic and extrinsic factors. Intrinsic regulation consists of the well-characterized ExsECDA partner-switching cascade, while extrinsic factors include global regulators that alter exsA transcription and/or translation. To identify novel extrinsic regulators of ExsA, we conducted a transposon mutagenesis screen in the absence of intrinsic control. Transposon disruptions within gene PA2840, which encodes a homolog of the Escherichia coli RNA-helicase DeaD, significantly reduced T3SS gene expression. Recent studies indicate that E. coli DeaD can promote translation by relieving inhibitory secondary structures within target mRNAs. We report here that PA2840, renamed DeaD, stimulates ExsA synthesis at the posttranscriptional level. Genetic experiments demonstrate that the activity of an exsA translational fusion is reduced in a deaD mutant. In addition, exsA expression in trans fails to restore T3SS gene expression in a deaD mutant. We hypothesized that DeaD relaxes mRNA secondary structure to promote exsA translation and found that altering the mRNA sequence of exsA or the native exsA Shine-Dalgarno sequence relieved the requirement for DeaD in vivo. Finally, we show that purified DeaD promotes ExsA synthesis using in vitro translation assays. Together, these data reveal a novel regulatory mechanism for P. aeruginosa DeaD and add to the complexity of global regulation of T3SS. IMPORTANCE Although members of the DEAD box family of RNA helicases are appreciated for their roles in mRNA degradation and ribosome biogenesis, an additional role in gene regulation is now emerging in bacteria. By relaxing secondary structures in mRNAs, DEAD box

  14. Heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst with enhanced photocatalytic activity and stability under visible light

    NASA Astrophysics Data System (ADS)

    Wang, Wan-Sheng; Du, Hong; Wang, Rui-Xia; Wen, Tao; Xu, An-Wu

    2013-03-01

    A heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst was prepared by a rational in situ ion exchange reaction between Ag3PO4 micro-cubes and Br- in aqueous solution followed by photoreduction. The photocatalytic activities of obtained photocatalysts were measured by the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation (λ >= 400 nm). Compared to AgBr/Ag, Ag3PO4/AgBr heterocrystals and pure Ag3PO4 crystals, the heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts exhibit much higher photocatalytic activity and stability. This enhanced photocatalytic activity suggests that the synergetic effects of the heterostructured Ag3PO4/AgBr/Ag and the strong SPR of Ag NPs on the surface result in the high efficiencies of the photocatalytic activity and the improved stability. With the assistance of Ag3PO4/AgBr/Ag heterostructures, only 8 min and 12 min are taken to completely decompose MO and MB molecules under visible-light irradiation, respectively. Furthermore, the photodegradation rate does not show an obvious decrease during ten successive cycles, indicating that our heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts are extremely stable under visible-light irradiation.A heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst was prepared by a rational in situ ion exchange reaction between Ag3PO4 micro-cubes and Br- in aqueous solution followed by photoreduction. The photocatalytic activities of obtained photocatalysts were measured by the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation (λ >= 400 nm). Compared to AgBr/Ag, Ag3PO4/AgBr heterocrystals and pure Ag3PO4 crystals, the heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts exhibit much higher photocatalytic activity and stability. This enhanced photocatalytic activity suggests that the synergetic effects of the heterostructured Ag3PO4/AgBr/Ag and the strong SPR of Ag NPs on the surface result in the high

  15. Technical efficiency of peripheral health units in Pujehun district of Sierra Leone: a DEA application

    PubMed Central

    Renner, Ade; Kirigia, Joses M; Zere, Eyob A; Barry, Saidou P; Kirigia, Doris G; Kamara, Clifford; Muthuri, Lenity HK

    2005-01-01

    Background The Data Envelopment Analysis (DEA) method has been fruitfully used in many countries in Asia, Europe and North America to shed light on the efficiency of health facilities and programmes. There is, however, a dearth of such studies in countries in sub-Saharan Africa. Since hospitals and health centres are important instruments in the efforts to scale up pro-poor cost-effective interventions aimed at achieving the United Nations Millennium Development Goals, decision-makers need to ensure that these health facilities provide efficient services. The objective of this study was to measure the technical efficiency (TE) and scale efficiency (SE) of a sample of public peripheral health units (PHUs) in Sierra Leone. Methods This study applied the Data Envelopment Analysis approach to investigate the TE and SE among a sample of 37 PHUs in Sierra Leone. Results Twenty-two (59%) of the 37 health units analysed were found to be technically inefficient, with an average score of 63% (standard deviation = 18%). On the other hand, 24 (65%) health units were found to be scale inefficient, with an average scale efficiency score of 72% (standard deviation = 17%). Conclusion It is concluded that with the existing high levels of pure technical and scale inefficiency, scaling up of interventions to achieve both global and regional targets such as the MDG and Abuja health targets becomes far-fetched. In a country with per capita expenditure on health of about US$7, and with only 30% of its population having access to health services, it is demonstrated that efficiency savings can significantly augment the government's initiatives to cater for the unmet health care needs of the population. Therefore, we strongly recommend that Sierra Leone and all other countries in the Region should institutionalise health facility efficiency monitoring at the Ministry of Health headquarter (MoH/HQ) and at each health district headquarter. PMID:16354299

  16. AGS experiments -- 1991, 1992, 1993. Tenth edition

    SciTech Connect

    Depken, J.C.

    1994-04-01

    This report contains: (1) FY 1993 AGS schedule as run; (2) FY 1994--95 AGS schedule; (3) AGS experiments {ge} FY 1993 (as of 30 March 1994); (4) AGS beams 1993; (5) AGS experimental area FY 1991 physics program; (6) AGS experimental area FY 1992 physics program; (7) AGS experimental area FY 1993 physics program; (8) AGS experimental area FY 1994 physics program (planned); (9) a listing of experiments by number; (10) two-page summaries of each experiment; (11) listing of publications of AGS experiments; and (12) listing of AGS experiments.

  17. AGS experiments -- 1995, 1996 and 1997

    SciTech Connect

    Depken, J.C.; Presti, P.L.

    1997-12-01

    This report contains (1) FY 1995 AGS schedule as run; (2) FY 1996 AGS schedule as run; (3) FY 1997 AGS schedule as run; (4) FY 1998--1999 AGS schedule (proposed); (5) AGS beams 1997; (6) AGS experimental area FY 1995 physics program; (7) AGS experimental area FY 1996 physics program; (8) AGS experimental area FY 1997 physics program; (9) AGS experimental area FY 1998--1999 physics program (proposed); (10) a listing of experiments by number; (11) two-page summaries of each experiment, in order by number; and (12) listing of publications of AGS experiments.

  18. Global effects of the DEAD-box RNA helicase DeaD (CsdA) on gene expression over a broad range of temperatures

    PubMed Central

    Vakulskas, Christopher A.; Pannuri, Archana; Cortés-Selva, Diana; Zere, Tesfalem R.; Ahmer, Brian M.; Babitzke, Paul; Romeo, Tony

    2014-01-01

    Summary In Escherichia coli, activity of the global regulatory RNA binding protein CsrA is antagonized by two noncoding sRNAs, CsrB and CsrC, which sequester it away from its lower affinity mRNA targets. Transcription of csrB/C requires the BarA-UvrY two component signal transduction system, which responds to short chain carboxylates. We show that two DEAD-box RNA helicases, DeaD and SrmB, activate csrB/C expression by different pathways. DeaD facilitates uvrY translation by counteracting the inhibitory effect of long distance basepairing between the uvrY mRNA leader and coding region, while SrmB does not affect UvrY or UvrY-phosphate levels. Contrary to the prevailing notion that these helicases act primarily at low temperatures, DeaD and SrmB activated csrB expression over a wide temperature range. High-throughput sequencing of RNA isolated by crosslinking immunoprecipitation (HITS-CLIP) revealed in vivo interactions of DeaD with 39 mRNAs, including those of uvrY and 9 other regulatory genes. Studies on the expression of several of the identified genes revealed regulatory effects of DeaD in all cases and diverse temperature response patterns. Our findings uncover an expanded regulatory role for DeaD, which is mediated through novel mRNA targets, important global regulators and under physiological conditions that were considered to be incompatible with its function. PMID:24708042

  19. Long-term pretreatment with desethylamiodarone (DEA) or amiodarone (AMIO) protects against coronary artery occlusion induced ventricular arrhythmias in conscious rats.

    PubMed

    Morvay, Nikolett; Baczkó, István; Sztojkov-Ivanov, Anita; Falkay, György; Papp, Julius Gy; Varró, András; Leprán, István

    2015-09-01

    The aim of this investigation was to compare the effectiveness of long-term pretreatment with amiodarone (AMIO) and its active metabolite desethylamiodarone (DEA) on arrhythmias induced by acute myocardial infarction in rats. Acute myocardial infarction was induced in conscious, male, Sprague-Dawley rats by pulling a previously inserted loose silk loop around the left main coronary artery. Long-term oral pretreatment with AMIO (30 or 100 mg·(kg body mass)(-1)·day(-1), loading dose 100 or 300 mg·kg(-1) for 3 days) or DEA (15 or 50 mg·kg(-1)·day(-1), loading dose 100 or 300 mg·kg(-1) for 3 days), was applied for 1 month before the coronary artery occlusion. Chronic oral treatment with DEA (50 mg·kg(-1)·day(-1)) resulted in a similar myocardial DEA concentration as chronic AMIO treatment (100 mg·kg(-1)·day(-1)) in rats (7.4 ± 0.7 μg·g(-1) and 8.9 ± 2.2 μg·g(-1)). Both pretreatments in the larger doses significantly improved the survival rate during the acute phase of experimental myocardial infarction (82% and 64% by AMIO and DEA, respectively, vs. 31% in controls). Our results demonstrate that chronic oral treatment with DEA resulted in similar cardiac tissue levels to that of chronic AMIO treatment, and offered an equivalent degree of antiarrhythmic effect against acute coronary artery ligation induced ventricular arrhythmias in conscious rats.

  20. Preparation and antibacterial activities of Ag/Ag+/Ag3+ nanoparticle composites made by pomegranate (Punica granatum) rind extract

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Ren, Yan-yu; Wang, Tao; Wang, Chuang

    Nano-silver and its composite materials are widely used in medicine, food and other industries due to their strong conductivity, size effect and other special performances. So far, more microbial researches have been applied, but a plant method is rarely reported. In order to open up a new way to prepare AgNP composites, pomegranate peel extract was used in this work to reduce Ag+ to prepare Ag/Ag+/Ag3+ nanoparticle composites. UV-Vis was employed to detect and track the reduction of Ag+ and the forming process of AgNPs. The composition, structure and size of the crystal were analyzed by XRD and TEM. Results showed that, under mild conditions, pomegranate peel extract reacted with dilute AgNO3 solution to produce Ag/Ag+/Ag3+ nanoparticle composites. At pH = 8 and 10 mmol/L of AgNO3 concentration, the size of the achieved composites ranged between 15 and 35 nm with spherical shapes and good crystallinity. The bactericidal experiment indicated that the prepared Ag/Ag+/Ag3+ nanoparticles had strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the newly synthesized Ag/Ag+/Ag3+ nanoparticles. This provided a useful clue to further study the AgNP biosynthesis mechanism.

  1. Ag/AgCl reference electrode in thionyl chloride electrolytes

    NASA Astrophysics Data System (ADS)

    Delnick, F. M.; Cieslak, W. R.

    1985-07-01

    Thionyl chloride is the active cathode and electrolyte solvent in Li/SOCl2 primary battery systems. To evaluate charge-transfer reactions in this solvent system, a reference electrode is required. This report describes the fabrication and characterization of Ag/AgCl microreference electrodes that can be used in SOCl2 battery electrolytes.

  2. Ag-Air Service

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Econ, Inc.'s agricultural aerial application, "ag-air," involves more than 10,000 aircraft spreading insecticides, herbicides, fertilizer, seed and other materials over millions of acres of farmland. Difficult for an operator to estimate costs accurately and decide what to charge or which airplane can handle which assignment most efficiently. Computerized service was designed to improve business efficiency in choice of aircraft and determination of charge rates based on realistic operating cost data. Each subscriber fills out a detailed form which pertains to his needs and then receives a custom-tailored computer printout best suited to his particular business mix.

  3. Construction of Ag/AgCl nanostructures from Ag nanoparticles as high-performance visible-light photocatalysts

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Liu, Dongzhi; Wang, Tianyang; Li, Wei; Hu, Wenping; Zhou, Xueqin

    2016-11-01

    A combined strategy of in situ oxidation and assembly is developed to prepare Ag/AgCl nanospheres and nanocubes from Ag nanoparticles under room temperature. It is a new facile way to fabricate Ag/AgCl with small sizes and defined morphologies. Ag/AgCl nanospheres with an average size of 80 nm were achieved without any surfactants, while Ag/AgCl nanocubes with a mean edge length of 150 nm were obtained by introduction of N-dodecyl- N, N-dimethyl-2-ammonio-acetate. The possible formation mechanism involves the self-assembly of AgCl nanoparticles, Ostwald ripening and photoreduction of Ag+ into Ag0 by the room light. The as-prepared Ag/AgCl nanospheres and nanocubes exhibit excellent photocatalytic activity and stability toward degradation of organic pollutants under visible-light irradiation. It is demonstrated that Ag/AgCl nanocubes display enhanced photocatalytic activity in comparison with Ag/AgCl nanospheres due to the more efficient charge transfer. This work may pave an avenue to construct various functional materials via the assembly strategy using nanoparticles as versatile building blocks.

  4. Communication: Structure, formation, and equilibration of ensembles of Ag-S complexes on an Ag surface

    SciTech Connect

    Russell, Selena M.; Kim, Yousoo; Liu, Da-Jiang; Evans, J. W.; Thiel, P. A.

    2013-02-15

    We have utilized conditions of very low temperature (4.7 K) and very low sulfur coverage to isolate and identify Ag-S complexes that exist on the Ag(111) surface. The experimental conditions are such that the complexes form at temperatures above the temperature of observation. These complexes can be regarded as polymeric chains of varying length, with an Ag4S pyramid at the core of each monomeric unit. Steps may catalyze the formation of the chains and this mechanism may be reflected in the chain length distribution.

  5. A study of the strategic alliance for EMS industry: the application of a hybrid DEA and GM (1, 1) approach.

    PubMed

    Wang, Chia Nan; Nguyen, Nhu Ty; Tran, Thanh Tuyen; Huong, Bui Bich

    2015-01-01

    Choosing a partner is a critical factor for success in international strategic alliances, although criteria for partner selection vary between developed and transitional markets. This study aims to develop effective methods to assist enterprise to measure the firms' operation efficiency, find out the candidate priority under several different inputs and outputs, and forecast the values of those variables in the future. The methodologies are constructed by the concepts of Data Envelopment Analysis (DEA) and grey model (GM). Realistic data in four consecutive years (2009-2012) a total of 20 companies of the Electronic Manufacturing Service (EMS) industry that went public are completely collected. This paper tries to help target company-DMU1-to find the right alliance partners. By our proposed approach, the results show the priority in the recent years. The research study is hopefully of interest to managers who are in manufacturing industry in general and EMS enterprises in particular.

  6. Measuring Efficiency of Knowledge Production in Health Research Centers Using Data Envelopment Analysis (DEA): A Case Study in Iran

    PubMed Central

    Amiri, Mohammad Meskarpour; Nasiri, Taha; Saadat, Seyed Hassan; Anabad, Hosein Amini; Ardakan, Payman Mahboobi

    2016-01-01

    Introduction Efficiency analysis is necessary in order to avoid waste of materials, energy, effort, money, and time during scientific research. Therefore, analyzing efficiency of knowledge production in health areas is necessary, especially for developing and in-transition countries. As the first step in this field, the aim of this study was the analysis of selected health research center efficiency using data envelopment analysis (DEA). Methods This retrospective and applied study was conducted in 2015 using input and output data of 16 health research centers affiliated with a health sciences university in Iran during 2010–2014. The technical efficiency of health research centers was evaluated based on three basic data envelopment analysis (DEA) models: input-oriented, output-oriented, and hyperbolic-oriented. The input and output data of each health research center for years 2010–2014 were collected from the Iran Ministry of Health and Medical Education (MOHE) profile and analyzed by R software. Results The mean efficiency score in input-oriented, output-oriented, and hyperbolic-oriented models was 0.781, 0.671, and 0.798, respectively. Based on results of the study, half of the health research centers are operating below full efficiency, and about one-third of them are operating under the average efficiency level. There is also a large gap between health research center efficiency relative to each other. Conclusion It is necessary for health research centers to improve their efficiency in knowledge production through better management of available resources. The higher level of efficiency in a significant number of health research centers is achievable through more efficient management of human resources and capital. Further research is needed to measure and follow the efficiency of knowledge production by health research centers around the world and over a period of time. PMID:28344756

  7. AGS Experiments: 1989, 1990, 1991

    SciTech Connect

    Depken, J.C.

    1992-02-01

    This report contains: Experimental areas layout; table of beam parameters and fluxes; experiment schedule as run''; proposed 1992 schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS Experiments begin here; and list of AGS Experimenters begins here.

  8. AGS Experiments: 1989, 1990, 1991

    SciTech Connect

    Depken, J.C.

    1992-02-01

    This report contains: Experimental areas layout; table of beam parameters and fluxes; experiment schedule ``as run``; proposed 1992 schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS Experiments begin here; and list of AGS Experimenters begins here.

  9. What Is Ag-Ed?

    ERIC Educational Resources Information Center

    Lindley, Judy

    Ag-Ed is an agricultural education project aimed at upper primary students, held in conjunction with the Toowoomba Show (similar to a county fair) in Queensland, Australia. The program achieves its purpose of helping children understand the impact and relevance that agriculture has on their everyday lives through two components, an Ag-Ed day and a…

  10. Plasmonic Ag2MoO4/AgBr/Ag composite: Excellent photocatalytic performance and possible photocatalytic mechanism

    NASA Astrophysics Data System (ADS)

    Wang, Zhongliao; Zhang, Jinfeng; Lv, Jiali; Dai, Kai; Liang, Changhao

    2017-02-01

    Plasmonic Ag2MoO4/AgBr/Ag composite is fabricated by in-situ ion exchange and reduction methods at room temperature. The samples are characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance (DRS), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM) and photoluminescence (PL) measurements. The results show that butterfly-like Ag2MoO4 nanosheets served as the precursor, and Ag2MoO4/AgBr/Ag is formed in phase transformation with MoO42- displaced by Br-. The ternary Ag2MoO4/AgBr/Ag composite photocatalysts show greatly enhanced photocatalytic activity in photodegrading methylene blue (MB) under visible light irradiation compared with AgBr and Ag2MoO4. The pseudo-first-order rate constant kapp of Ag2MoO4/AgBr/Ag is 0.602 min-1, which is 11.6 and 18.3 times as high as that of AgBr and Ag2MoO4, respectively. Meanwhile, the efficiency of degradation still kept 90% after ten times cyclic experiments. Eventually, possible photocatalytic mechanism was proposed.

  11. AgH, Ag/sub 2/, and AgO revisited: Basis set extensions

    SciTech Connect

    Martin, R.L.

    1987-05-01

    An extended basis set has been developed for Ag which significantly improves the agreement between theoretical and experimental spectroscopic parameters for AgH, AgO, and Ag/sub 2/. The major improvement comes about as a result of the improved treatment of electron correlation in the Ag d shell upon the introduction of f functions. Their inclusion produces very slight differences at the SCF level, but significant reductions in r/sub e/ and increases in ..omega../sub e/ and D/sub e/ in the Mo-dash-barller--Plesset perturbation theory expansion. At the MP4(SDTQ) level, typical results are 0.02 A too long for r/sub e/, 4% too low for ..omega../sub e/, and 10 kcal too small for D/sub e/. From a pragmatic standpoint, MP2 give results very similar to this at a much reduced level of effort.

  12. THE AGS ELECTROSTATIC SEPTUM.

    SciTech Connect

    HOCK,J.RUSSO,T.GLEN,J.BROWN,K.

    2003-05-12

    The previous slow beam extraction electro static septum in the AGS was designed in 1981. Research documented at the Fermi Laboratory was used as the base line for this design. The septum consisted of a ground plane of .002 inch diameter wire tungsten-rhenium alloy (75%W 25%Re) with a hollow welded titanium cathode assembly. The vacuum chamber is stationary and the septum is moved with a pair of high vacuum linear feed throughs. After years of beam time, the frequency of failures increased. The vacuum system design was poor by today's standards and resulted in long pump down times after repairs. The failures ranged from broken septum wires to a twisted cathode. In addition to the failures, the mechanical drive system had too much backlash, making the operating position difficult to repeat. The new septum needed to address all of these issues in order to become a more reliable septum.

  13. The AGS-Booster lattice

    SciTech Connect

    Lee, Y.Y.; Barton, D.S.; Claus, J.; Cottingham, J.G.; Courant, E.D.; Danby, G.T.; Dell, G.F.; Forsyth, E.B.; Gupta, R.C.; Kats, J.

    1987-01-01

    The AGS Booster has three objectives. They are to increase the space charge limit of the AGS, to increase the intensity of the polarized proton beam by accumulating many linac pulses (since the intensity is limited by the polarized ion source), and to reaccelerate heavy ions from the BNL Tandem Van de Graaff before injection into the AGS. The machine is capable of accelerating protons at 7.5 Hertz from 200 MeV to 1.5 GeV or to lower final energies at faster repetition rates. The machine will also be able to accelerate heavy ions from as low as 1 MeV/nucleon to a magnetic rigidity as high as 17.6 Tesla-meters with a one second repetition rate. As an accumulator for polarized protons, the Booster should be able to store the protons at 200 MeV for several seconds. We expect that the Booster will increase the AGS proton intensity by a factor of four, polarized proton intensity by a factor of twenty to thirty, and will also enable the AGS to accelerate all species of heavy ions (at present the AGS heavy ion program is limited to the elements lighter than sulfur because it can only accelerate fully stripped ions). The construction project started in FY 1985 and is expected to be completed in 1989. The purpose of this paper is to provide a future reference for the AGS Booster lattice.

  14. Spin dynamics simulations at AGS

    SciTech Connect

    Huang, H.; MacKay, W.W.; Meot, F.; Roser, T.

    2010-05-23

    To preserve proton polarization through acceleration, it is important to have a correct model of the process. It has been known that with the insertion of the two helical partial Siberian snakes in the Alternating Gradient Synchrotron (AGS), the MAD model of AGS can not deal with a field map with offset orbit. The stepwise ray-tracing code Zgoubi provides a tool to represent the real electromagnetic fields in the modeling of the optics and spin dynamics for the AGS. Numerical experiments of resonance crossing, including spin dynamics in presence of the snakes and Q-jump, have been performed in AGS lattice models, using Zgoubi. This contribution reports on various results so obtained.

  15. Ag-Pd-Si (009)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 1 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Ag-Pd-Si (009)' with the content:

  16. Facile synthesis, structure, and properties of Ag2S/Ag heteronanostructure

    NASA Astrophysics Data System (ADS)

    Sadovnikov, S. I.; Gusev, A. I.

    2016-09-01

    Ag2S/Ag heteronanostructure has been produced by a simple one-stage chemical deposition from aqueous solutions of silver nitrate, sodium sulfide, and sodium citrate with the use of monochromatic light irradiation. For simultaneous synthesis of Ag2S and Ag nanoparticles, deposition has been performed from reaction mixtures with reduced sodium sulfide concentration. The size of Ag2S and Ag nanoparticles is 45-50 and 15-20 nm, respectively. It is established that in the contact layer between silver sulfide and silver, nonconducting α-Ag2S acanthite transforms into superionic β-Ag2S argentite under the action of external electric field. The scheme of the operation of a resistive switch based on an Ag2S/Ag heteronanostructure is proposed. The UV-Vis optical absorption spectra of colloidal solutions of Ag2S/Ag heteronanostructures have been studied.

  17. Enhanced photocatalytic activity of Ag-TiO2/Ag heterogeneous films

    NASA Astrophysics Data System (ADS)

    Liang, Ying; Wang, ShaoHua; Guo, PengFeng

    2015-11-01

    Ag-deposited TiO2 and Ag (Ag-TiO2/Ag) films coated on glass substrates were prepared using a simple sol-gel and dip-coating method. The Ag chemical state was investigated through X-ray diffractometry and X-ray photoelectron spectroscopy. Results showed that the Ag mainly exists in metallic state in the Ag-TiO2 film. Ag-TiO2/Ag exhibits higher photocatalytic activity than individual Ag-TiO2 and TiO2/Ag films. This enhanced photocatalytic activity was attributed to high surface plasmon resonance effects and separation rates of photoinduced electron-hole pairs of Ag nanoparticles. Results were verified by photoluminescence and UV-Vis spectroscopy.

  18. Knowledge discovery from data and Monte-Carlo DEA to evaluate technical efficiency of mental health care in small health areas

    PubMed Central

    García-Alonso, Carlos; Pérez-Naranjo, Leonor

    2009-01-01

    Introduction Knowledge management, based on information transfer between experts and analysts, is crucial for the validity and usability of data envelopment analysis (DEA). Aim To design and develop a methodology: i) to assess technical efficiency of small health areas (SHA) in an uncertainty environment, and ii) to transfer information between experts and operational models, in both directions, for improving expert’s knowledge. Method A procedure derived from knowledge discovery from data (KDD) is used to select, interpret and weigh DEA inputs and outputs. Based on KDD results, an expert-driven Monte-Carlo DEA model has been designed to assess the technical efficiency of SHA in Andalusia. Results In terms of probability, SHA 29 is the most efficient being, on the contrary, SHA 22 very inefficient. 73% of analysed SHA have a probability of being efficient (Pe) >0.9 and 18% <0.5. Conclusions Expert knowledge is necessary to design and validate any operational model. KDD techniques make the transfer of information from experts to any operational model easy and results obtained from the latter improve expert’s knowledge.

  19. Comparing and contrasting poverty reduction performance of social welfare programs across jurisdictions in Canada using Data Envelopment Analysis (DEA): an exploratory study of the era of devolution.

    PubMed

    Habibov, Nazim N; Fan, Lida

    2010-11-01

    In the mid-1990s, the responsibilities to design, implement, and evaluate social welfare programs were transferred from federal to local jurisdictions in many countries of North America and Europe through devolution processes. Devolution has caused the need for a technique to measure and compare the performances of social welfare programs across multiple jurisdictions. This paper utilizes Data Envelopment Analysis (DEA) for a comparison of poverty reduction performances of jurisdictional social welfare programs across Canadian provinces. From the theoretical perspective, findings of this paper demonstrates that DEA is a promising method to evaluate, compare, and benchmark poverty reduction performance across multiple jurisdictions using multiple inputs and outputs. This paper demonstrates that DEA generates easy to comprehend composite rankings of provincial performances, identifies appropriate benchmarks for each inefficient province, and estimates sources and amounts of improvement needed to make the provinces efficient. From a practical perspective the empirical results presented in this paper indicate that Newfoundland, Prince Edwards Island, and Alberta achieve better efficiency in poverty reduction than other provinces. Policy makers and social administrators of the ineffective provinces across Canada may find benefit in selecting one of the effective provinces as a benchmark for improving their own performance based on similar size and structure of population, size of the budget for social programs, and traditions with administering particular types of social programs.

  20. Chronic administration of the HNO donor Angeli's salt does not lead to tolerance, cross-tolerance, or endothelial dysfunction: comparison with GTN and DEA/NO.

    PubMed

    Irvine, Jennifer C; Kemp-Harper, Barbara K; Widdop, Robert E

    2011-05-01

    Nitroxyl (HNO) displays distinct pharmacology to its redox congener nitric oxide (NO(•)) with therapeutic potential in the treatment of heart failure. It remains unknown if HNO donors are resistant to tolerance development following chronic in vivo administration. Wistar-Kyoto rats received a 3-day subcutaneous infusion of one of the NO(•) donors, glyceryl trinitrate (GTN) or diethylamine/NONOate (DEA/NO), or the HNO donor Angeli's salt (AS). GTN infusion (10 μg/kg/min) resulted in significantly blunted depressor responses to intravenous bolus doses of GTN, demonstrating tolerance development. By contrast, infusion with AS (20 μg/kg/min) or DEA/NO (2 μg/kg/min) did not alter their subsequent depressor responses. Similarly, ex vivo vasorelaxation responses in isolated aortae revealed that GTN infusion elicited a significant 6-fold decrease in the sensitivity to GTN and reduction in the maximum response to acetylcholine (ACh). Chronic infusion of AS or DEA/NO had no effect on subsequent vasorelaxation responses to themselves or to ACh. No functional cross-tolerance between nitrovasodilators was evident, either in vivo or ex vivo, although an impaired ability of a nitrovasodilator to increase tissue cGMP content was not necessarily indicative of a reduced functional response. In conclusion, HNO donors may represent novel therapies for cardiovascular disease with therapeutic potential over clinically used organic nitrates.

  1. Study of the oxygen transport through Ag (110), Ag (poly), and Ag 2.0 Zr

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.; Wu, D.; Davidson, M. R.; Hoflund, Gar B.

    1992-01-01

    The transport of oxygen through high-purity membranes of Ag (110), Ag (poly), Ag (nano), and Ag 2.0 Zr has been studied by an ultrahigh vacuum permeation method over the temperature range of 400-800 C. The data show that there are substantial deviations from ordinary diffusion-controlled transport. A surface limitation has been confirmed by glow-discharge studies where the upstream O2 supply has been partially converted to atoms, which, for the same temperature and pressure, gave rise to over an order of magnitude increase in transport flux. Further, the addition of 2.0 wt percent Zr to the Ag has provided increased dissociative adsorption rates, which, in turn, increased the transport flux by a factor of 2. It was also observed that below a temperature of 630 C, the diffusivity exhibits an increase in activation energy of over 4 kcal/mol, which has been attributed to trapping of the atomic oxygen and/or kinetic barriers at the surface and subsurface of the vacuum interface. Above 630 C, the activation barrier decreases to the accepted value of about 11 kcal/mol for Ag (poly), consistent with zero concentration at the vacuum interface.

  2. Integrated DEA models and grey system theory to evaluate past-to-future performance: a case of Indian electricity industry.

    PubMed

    Wang, Chia-Nan; Nguyen, Nhu-Ty; Tran, Thanh-Tuyen

    2015-01-01

    The growth of economy and population together with the higher demand in energy has created many concerns for the Indian electricity industry whose capacity is at 211 gigawatts mostly in coal-fired plants. Due to insufficient fuel supply, India suffers from a shortage of electricity generation, leading to rolling blackouts; thus, performance evaluation and ranking the industry turn into significant issues. By this study, we expect to evaluate the rankings of these companies under control of the Ministry of Power. Also, this research would like to test if there are any significant differences between the two DEA models: Malmquist nonradial and Malmquist radial. Then, one advance model of MPI would be chosen to see these companies' performance in recent years and next few years by using forecasting results of Grey system theory. Totally, the realistic data 14 are considered to be in this evaluation after the strict selection from the whole industry. The results found that all companies have not shown many abrupt changes on their scores, and it is always not consistently good or consistently standing out, which demonstrated the high applicable usability of the integrated methods. This integrated numerical research gives a better "past-present-future" insights into performance evaluation in Indian electricity industry.

  3. Curing behavior and reaction kinetics of binder resins for 3D-printing investigated by dielectric analysis (DEA)

    NASA Astrophysics Data System (ADS)

    Möginger, B.; Kehret, L.; Hausnerova, B.; Steinhaus, J.

    2016-05-01

    3D-Printing is an efficient method in the field of additive manufacturing. In order to optimize the properties of manufactured parts it is essential to adapt the curing behavior of the resin systems with respect to the requirements. Thus, effects of resin composition, e.g. due to different additives such as thickener and curing agents, on the curing behavior have to be known. As the resin transfers from a liquid to a solid glass the time dependent ion viscosity was measured using DEA with flat IDEX sensors. This allows for a sensitive measurement of resin changes as the ion viscosity changes two to four decades. The investigated resin systems are based on the monomers styrene and HEMA. To account for the effects of copolymerization in the calculation of the reaction kinetics it was assumed that the reaction can be considered as a homo-polymerization having a reaction order n≠1. Then the measured ion viscosity curves are fitted with the solution of the reactions kinetics - the time dependent degree of conversion (DC-function) - for times exceeding the initiation phase representing the primary curing. The measured ion viscosity curves can nicely be fitted with the DC-function and the determined fit parameters distinguish distinctly between the investigated resin compositions.

  4. Irrigation pricing policies and its impact on agricultural inputs demand in Tunisia: a DEA-based methodology.

    PubMed

    Frija, Aymen; Wossink, Ada; Buysse, Jeroen; Speelman, Stijn; Van Huylenbroeck, Guido

    2011-09-01

    This paper estimates farmers' individual irrigation water demand functions employing the information hidden in individual farmers' technical efficiency. This information is extracted through the development of a new deductive methodology based on inverse Data Envelopment Analysis (DEA) models. The empirical results for Tunisia show that farmers who are more technically efficient have less elastic irrigation water demand functions; these farmers would adjust demand only to a limited extent and they can afford the water price. In contrast, water pricing significantly affects those that are less efficient. These farmers shift towards a different cropping pattern using significantly less water and more land when the price of water increases. Thus, higher water prices would threaten this category's livelihood if their efficiency is not improved. However, if the technical efficiency of these farmers were to improve, then it would be more difficult to reach water saving objectives since their demand will also become highly inelastic. The findings have important implications in view of the objectives of Tunisia water policy which include:full cost recovery, continuity of the irrigation activity, and water saving at the national level.

  5. Modeling CO{sub 2} and H{sub 2}S solubility in MDEA and DEA: Design implications

    SciTech Connect

    Rochelle, G.T.; Posey, M.

    1996-12-31

    The solubility of H{sub 2}S and CO{sub 2} in aqueous alkanolamines affects solution capacity and the required circulation rate for acid gas absorption. These thermodynamics also determine the relationship of steam rate and the lean loading of the solution which in turn sets the leak of acid gas from the top of the absorber. Finally, the mechanisms of mass transfer and the role of kinetics, especially in stripping, depend on the vapor/liquid equilibria. Published measurements of CO{sub 2} and H{sub 2}S solubility in methyldiethanolamine (MDEA) and diethanolamine (DEA) are not in general agreement, especially at low loading of acid gas. The available sets of solubility data have been regressed with the AspenPlus electrolyte/NRTL model. All of the parameters and constants that make up this model have been carefully evaluated. Independent thermodynamic data such as freezing point and heat of mixing have been included in the regression to strengthen the estimates of model parameters. The parameters for each set of solubility data have been evaluated in an attempt to determine which set is correct. Each evaluated model has been used to calculate the acid gas capacity and minimum stripping steam rate for several industrial cases of acid gas absorption/stripping.

  6. Integrated DEA Models and Grey System Theory to Evaluate Past-to-Future Performance: A Case of Indian Electricity Industry

    PubMed Central

    Wang, Chia-Nan; Tran, Thanh-Tuyen

    2015-01-01

    The growth of economy and population together with the higher demand in energy has created many concerns for the Indian electricity industry whose capacity is at 211 gigawatts mostly in coal-fired plants. Due to insufficient fuel supply, India suffers from a shortage of electricity generation, leading to rolling blackouts; thus, performance evaluation and ranking the industry turn into significant issues. By this study, we expect to evaluate the rankings of these companies under control of the Ministry of Power. Also, this research would like to test if there are any significant differences between the two DEA models: Malmquist nonradial and Malmquist radial. Then, one advance model of MPI would be chosen to see these companies' performance in recent years and next few years by using forecasting results of Grey system theory. Totally, the realistic data 14 are considered to be in this evaluation after the strict selection from the whole industry. The results found that all companies have not shown many abrupt changes on their scores, and it is always not consistently good or consistently standing out, which demonstrated the high applicable usability of the integrated methods. This integrated numerical research gives a better “past-present-future” insights into performance evaluation in Indian electricity industry. PMID:25821854

  7. Effect of Ag Templates on the Formation of Au-Ag Hollow/Core-Shell Nanostructures.

    PubMed

    Tsai, Chi-Hang; Chen, Shih-Yun; Song, Jenn-Ming; Haruta, Mitsutaka; Kurata, Hiroki

    2015-12-01

    Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study. By means of galvanic replacement, twined Ag nanoparticles (NPs) and single-crystalline Ag nanowires (NWs) were adopted as templates, respectively, and alloyed with the same amount of Au(+) ions. High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1. The shifts of surface plasmon resonance and chemical composition reveal the evolution of the alloy ring formation. On the other hand, single-crystalline Ag NWs became Ag@AuAg core-shell wires instead of hollow nanostructure through a process of galvanic replacement. It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures.

  8. Probing the rupture of a Ag atomic junction in a Ag-Au mixed electrode

    NASA Astrophysics Data System (ADS)

    Kim, Taekyeong

    2015-09-01

    We probed that the atomic junction in Ag part ruptures during stretching of atomic sized contacts of Ag-Au mixed electrodes, resulting in Ag-Ag electrodes through a scanning tunneling microscope breaking junction (STM-BJ) technique. We observed that the conductance and tunneling decay constant for a series of amine-terminated oligophenyl molecular junctions are essentially the same for the Ag-Au mixed and the Ag-Ag electrodes. We also found the molecular plateau length and the evolution patterns with the Ag-Au mixed electrodes are similar to those with Ag-Ag electrodes rather than the Au-Au electrodes in the molecular junction elongation. This result is attributed to the smaller binding energy of Ag atoms compared to that of Au atoms, so the Ag junction part is more easily broken than that of Au part in stretching of Ag-Au mixed electrodes. Furthermore, we successfully observed that the rupture force of the atomic junction for the Ag-Au mixed electrodes was identical to that for the Ag-Ag electrodes and smaller than that for the Au-Au electrodes. This study may advance the understanding of the electrical and the mechanical properties in molecular devices with Ag and Au electrodes in future.

  9. AG Draconis - a symbiotic mystery

    NASA Astrophysics Data System (ADS)

    Galis, R.; Hric, L.; Smelcer, L.

    2015-02-01

    Symbiotic system AG Draconis regularly undergoes quiescent and active stages which consist of the series of individual outbursts. The period analysis of new and historical photometric data, as well as radial velocities, confirmed the presence of the two periods. The longer one (~550 d) is related to the orbital motion and the shorter one (~355 d) could be due to pulsation of the cool component of AG Dra. In addition, the active stages change distinctively, but the outbursts are repeated with periods from 359 - 375 d.

  10. Studies of induced radioactivity at the AGS

    SciTech Connect

    Brown, K.A.; Tanaka, M.

    1987-01-01

    With the goals of higher proton intensities, along with the many modes the AGS now runs and those being commissioned to run, we have begun detailed studies of the beam induced radioactivity in the AGS.

  11. Assessment of groundwater quality using DEA and AHP: a case study in the Sereflikochisar region in Turkey.

    PubMed

    Kavurmaci, Murat; Üstün, A Korkut

    2016-04-01

    This study investigated the spatial distribution of groundwater quality in Sereflikochisar Basin, in the Central Anatolian region of Turkey using different hydrochemical, statistical, and geostatistical methods. A total of 51 groundwater samples were collected from the observation wells in the study area to evaluate the characteristics of the groundwater quality. As a relatively simple and practical method, a groundwater quality index (GWQI) was developed to evaluate the overall groundwater quality. In this process, complex decision-making techniques such as analytic hierarchy process (AHP) and data envelopment analysis (DEA) were used. Based on these models, two new indices (A-GWQI and D-GWQI) were proposed. According to the D-GWQI score (from 0.6 to 1), water quality was classified in four categories as unsuitable (0.6–0.7), permissible (0.7–0.8), good (0.8–0.9), and excellent (0.9–1). The spatial distribution maps of the groundwater quality were created using the Kriging method. For each map, seven different semivariogram models were tested and the best-fitted model was chosen based on their root mean square standardized error. These maps showed that the areas with high groundwater quality were in the eastern and southern parts of the study area where the D-GWQI scores were greater than 0.8. Depending on the distance from the Salt Lake, the characteristics of groundwater changed from NaCl to NaHCO3 and CaHCO3 facies. This study shows how to determine the spatial distribution of the groundwater quality and identify the impact of salt lakes on the groundwater quality in inland aquifers. The findings of this study can be applied to ensure the quality of groundwater used for drinking and irrigation purposes in the study area.

  12. Ag nanotubes and Ag/AgCl electrodes in nanoporous membranes.

    PubMed

    Davenport, Matthew; Healy, Ken; Siwy, Zuzanna S

    2011-04-15

    Miniaturization of the entire experimental setup is a key requirement for widespread application of nanodevices. For nanopore biosensing, integrating electrodes onto the nanopore membrane and controlling the pore length is important for reducing the complexity and improving the sensitivity of the system. Here we present a method to achieve these goals, which relies on electroless plating to produce Ag nanotubes in track-etched polymer nanopore templates. By plating from one side only, we create a conductive nanotube that does not span the full length of the pore, and thus can act as a nanoelectrode located inside the nanopore. To give optimal electrochemical behavior for sensing, we coat the Ag nanotube with a layer of AgCl. We characterize the behavior of this nanoelectrode by measuring its current-voltage response and find that, in most cases, the response is asymmetric. The plated nanopores have initial diameters between 100 and 300 nm, thus a range suitable for detection of viruses.

  13. Loading effect of Ag/AgO on the photocatalytic performance of ZnO rods

    NASA Astrophysics Data System (ADS)

    Samsuddin, Aida Fitri; Aziz, Siti Nor Qurratu Aini Abd; Pung, Swee-Yong

    2017-01-01

    The photocatalytic performance of ZnO rods in degradation of Rhodamine B dye under UV light was improved by 7.3% via deposition of Ag/AgO using 1.0 × 10-3 g mL-1 of silver nitrate solution. However, its photodegradation efficiency decreased with the increase in silver nitrate concentration which was used to prepare the Ag/AgO-ZnO rods. This result suggests that the loading of Ag/AgO on the surface of ZnO rods affected the photocatalytic performance differently. The scavenger study indicates that the main reactive species responsible for the degradation of Rhodamine B dye by Ag-/AgO-deposited ZnO rods were holes, followed by superoxide anion free radicals, hydroxyl free radicals and electrons. Based on these findings, a refined photodegradation mechanism of Rhodamine B by Ag/AgO-ZnO rods is proposed.

  14. AGS experiments: 1990, 1991, 1992. Ninth edition

    SciTech Connect

    Depken, J.C.

    1993-04-01

    This report contains a description of the following: AGS Experimental Area - High Energy Physics FY 1993 and Heavy Ion Physics FY 1993; Table of Beam Parameters and Fluxes; Experiment Schedule ``as run``; Proposed 1993 Schedule; A listing of experiments by number; Two-page summaries of each experiment begin here, also ordered by number; Publications of AGS Experiments; and List of AGS Experimenters.

  15. Activation properties of Ag+-ion conduction in bulk amorphous AgI: estimation from extrapolation of the AgI composition dependence in AgI Ag2O P2O5 glasses

    NASA Astrophysics Data System (ADS)

    Hanaya, M.; Hatate, A.; Oguni, M.

    2003-06-01

    AgI-based fast-ion conducting glasses with very high AgI compositions from the (AgI)x(AgPO3)1-x, (AgI)x(Ag2PO3.5)1-x, and (AgI)x(Ag3PO4)1-x systems were prepared successfully by using a rapid-press quenching and a twin-roller quenching method. The ac dielectric measurements showed common relaxation properties of Ag+-ion conduction in the glasses independently of the species of the glass network formers of AgPO3, Ag2PO3.5, and Ag3PO4, and the activation energies, Δɛa, for Ag+-ion conduction were observed to converge upon the same magnitude of ~26 kJ mol-1 at the AgI composition limit of x = 1. This indicates the formation of amorphous AgI regions in the glasses, and the value of Δɛa = 26 +/- 1 kJ mol-1 estimated at x = 1 was concluded to correspond to that for bulk amorphous AgI which has never been obtained experimentally.

  16. AGS 20th anniversary celebration

    SciTech Connect

    Baggett, N.V.

    1980-05-22

    On May 22, 1980, a symposium was held at Brookhaven to celebrate the 20th birthday of the AGS, to recall its beginnings, and to review major discoveries that have been made with its beams. The talks at the symposium are recorded in this volume.

  17. AGS experiments, 1988, 1989, 1990

    SciTech Connect

    Depken, J.C.

    1991-04-01

    This report contains: experimental areas layout; table of beam parameters and fluxes; experiment schedule as run''; experiment long range schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS experiments; and list of experimenters.

  18. AGS experiments: 1985, 1986, 1987

    SciTech Connect

    Depken, J.C.

    1987-01-01

    This report contains: Experimental areas layout, table of beam parameters and fluxes, experiment schedule ''as run,'' experiment long range schedule, a listing of experiments by number, two-page summaries of each experiment, also ordered by number, and publications of AGS experiments, 1982-1987.

  19. Antibacterial activity and reusability of CNT-Ag and GO-Ag nanocomposites

    NASA Astrophysics Data System (ADS)

    Kim, Ji Dang; Yun, Hyosuk; Kim, Gwui Cheol; Lee, Chul Won; Choi, Hyun Chul

    2013-10-01

    A facile approach to the synthesis of novel CNT-Ag and GO-Ag antibacterial materials, in which thiol groups are utilized as linkers to secure silver (Ag) nanoparticles to the CNT and GO surfaces without agglomeration, is reported. The resulting CNT-Ag and GO-Ag samples were characterized by performing TEM, XRD, Auger, XPS, and Raman measurements, which revealed that in these antibacterial materials size-similar and quasi-spherical Ag nanoparticles are anchored to the CNT and GO surfaces. The Ag nanoparticles in CNT-Ag and GO-Ag have narrow size distributions with average diameters of 2.6 and 3.5 nm respectively. The antibacterial activities of CNT-Ag and GO-Ag against Escherichia coli were assessed with the paper-disk diffusion method and by determining the minimal inhibitory concentrations (MICs). CNT-Ag was found to have higher antibacterial activity than the reference Ag colloid. Moreover, both CNT-Ag and GO-Ag retain more than 50% of their original antibacterial activities after 20 washes with detergent, which indicates their potential as antibacterial materials for laboratory and medical purposes.

  20. Comparative Study of Antimicrobial Activity of AgBr and Ag Nanoparticles (NPs)

    PubMed Central

    Suchomel, Petr; Kvitek, Libor; Panacek, Ales; Prucek, Robert; Hrbac, Jan; Vecerova, Renata; Zboril, Radek

    2015-01-01

    The diverse mechanism of antimicrobial activity of Ag and AgBr nanoparticles against gram-positive and gram-negative bacteria and also against several strains of candida was explored in this study. The AgBr nanoparticles (NPs) were prepared by simple precipitation of silver nitrate by potassium bromide in the presence of stabilizing polymers. The used polymers (PEG, PVP, PVA, and HEC) influence significantly the size of the prepared AgBr NPs dependently on the mode of interaction of polymer with Ag+ ions. Small NPs (diameter of about 60–70 nm) were formed in the presence of the polymer with low interaction as are PEG and HEC, the polymers which interact with Ag+ strongly produce nearly two times bigger NPs (120–130 nm). The prepared AgBr NPs were transformed to Ag NPs by the reduction using NaBH4. The sizes of the produced Ag NPs followed the same trends – the smallest NPs were produced in the presence of PEG and HEC polymers. Prepared AgBr and Ag NPs dispersions were tested for their biological activity. The obtained results of antimicrobial activity of AgBr and Ag NPs are discussed in terms of possible mechanism of the action of these NPs against tested microbial strains. The AgBr NPs are more effective against gram-negative bacteria and tested yeast strains while Ag NPs show the best antibacterial action against gram-positive bacteria strains. PMID:25781988

  1. Characterization of spark plasma sintered Ag nanopowders.

    PubMed

    Fu, Y Q; Shearwood, C; Xu, B; Yu, L G; Khor, K A

    2010-03-19

    The low temperature sintering behaviour of nanocrystalline Ag powder (with an average size of 70 nm) was characterized. Using spark plasma sintering (SPS), the Ag nanopowders can be successfully sintered at low pressure for only 5 min without external heating, and the sintering density increases and porosity decreases significantly with increase in the sintering temperature. Nanoindentation has been used to characterize the SPS sintered Ag samples. The mechanisms of the low sintering temperature behaviour of the nano-Ag powder and the nanoscale mechanical performance have been discussed. Compression tests were also used to characterize the mechanical properties of the sintered Ag sample with a maximum strain up to 15%.

  2. Synergistic effect of interfacial lattice Ag(+) and Ag(0) clusters in enhancing the photocatalytic performance of TiO2.

    PubMed

    Xu, Liming; Zhang, Dandan; Ming, Lufei; Jiao, Yanchao; Chen, Feng

    2014-09-28

    An interfacial lattice Ag(+) doped on TiO2 (Ag(+)/TiO2) was prepared by eluting Ag(0) clusters from a hydrothermally prepared Ag(0)/Ag(+)/TiO2 composite. An Ag(+)/TiO2@Ag(0) composite photocatalyst was subsequently obtained via a secondary Ag(0) clusters loading process to the Ag(+)/TiO2. The photocatalytic activity of Ag(+)/TiO2@Ag(0) was greatly improved compared to Ag(0)/Ag(+)/TiO2 and Ag(+)/TiO2. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) testing verified that Ag(+) ions occur as an interfacial lattice Ag(+) species in the composites. The enhancement effect of the interfacial lattice Ag(+) species is exhibited by the newly-formed Ag(+)/TiO2@Ag(0) as the interfacial lattice Ag(+) is fully exposed but not overlapped with the re-loaded Ag(0) clusters. The interfacial lattice Ag(+) ions and Ag(0) clusters are both responsible for the photocatalytic performance improvement of the catalyst, in either the photocatalytic degradation of methyl orange or photocurrent measurement.

  3. Enhancing the ag precipitation by surface mechanical attrition treatment on Cu-Ag alloys

    NASA Astrophysics Data System (ADS)

    Liu, Jiabin; Zhang, Lehao; Liu, Jingjing; Huang, Liuyi; Gu, Hao; Fang, Youtong; Meng, Liang; Zhang, Jian

    2016-09-01

    The influence of surface mechanical attrition treatment (SMAT) on Ag precipitation in Cu-Ag alloys was investigated. Cu-6 wt% Ag was melt, cold rolled and solution treated to be Cu-Ag solid solution, which was either aged at 250 and 350 °C for 24 h directly or SMAT-ed before aging. Ag precipitates were hard be found in the directly aged Cu-Ag sample while they were observed clearly in the SMAT-ed counterpart at 250 °C. The Ag precipitates formed in the surface layer by SMAT are much coarser than those in the un-SMAT-ed sample. It is obvious that the precipitating behavior of Ag was promoted significantly by SMAT approach. A large number of defects were generated by SMAT and they were acting as fast atomic diffusion channels that facilitated the atomic diffusion of Ag.

  4. Polymorphism of LiAg

    NASA Astrophysics Data System (ADS)

    Pavlyuk, V. V.; Dmytriv, G. S.; Tarasiuk, I. I.; Chumak, I. V.; Pauly, H.; Ehrenberg, H.

    2010-02-01

    A phase transition from the cubic CsCl-type structure (Pm-3m space group) into a tetragonal UPb-type structure (I4 1/amd) is observed for the LiAg binary compound at ambient conditions. The crystal structure of the tetragonal modification of the LiAg binary compound was solved by direct methods in SHELXS on the base of structure factors which were extracted from a powder diffraction pattern and refined by SHELXL and the Rietveld method ( a = 3.9605(1), c = 8.2825(2) Å, Bragg R-factor = 4.81, Rf-factor = 4.87). Elevated temperatures and/or a small Li-excess versus the equimolar composition favour the cubic structure whereas ambient and lower temperatures and/or a small Li-deficiency stabilize the tetragonal structure. This reconstructive transition is reversible but proceeds slowly.

  5. Capacitive deionization of seawater effected by nano Ag and Ag@C on graphene.

    PubMed

    Cai, P-F; Su, C-J; Chang, W-T; Chang, F-C; Peng, C-Y; Sun, I-W; Wei, Y-L; Jou, C-J; Wang, H Paul

    2014-08-30

    Drinking water shortage has become worse in recent decades. A new capacitive deionization (CDI) method for increasing water supplies through the effective desalination of seawater has been developed. Silver as nano Ag and Ag@C which was prepared by carbonization of the Ag(+)-β-cyclodextrin complex at 573 K for 30 min can add the antimicrobial function into the CDI process. The Ag@C and Ag nanoparticles dispersed on reduced graphene oxide (Ag@C/rGO and nano Ag/rGO) were used as the CDI electrodes. The nano Ag/rGO and Ag@C/rGO electrodes can reduce the charging resistant, and enhance the electrosorption capability. Better CDI efficiencies with the nano Ag/rGO and Ag@C/rGO electrodes can therefore be obtained. When reversed the voltage, the electrodes can be recovered up to 90% within 5 min. This work presents the feasibility for the nano Ag and Ag@C on rGO electrodes applied in CDI process to produce drinking water from seawater or saline water.

  6. Facile synthesis of S-Ag nanocomposites and Ag2S short nanorods by the interaction of sulfur with AgNO3 in PEG400

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Li; Xie, Xin-Yuan; Liang, Ming; Xie, Shu-Ming; Chen, Jie-Mei; Zheng, Wen-Jie

    2016-06-01

    A facile, eco-friendly and inexpensive method to prepare Ag2S short nanorods and S-Ag nanocomposites using sublimed sulfur, AgNO3, PVP and PEG400 was studied. According to x-ray diffraction and scanning electron microscopy of the Ag2S, the products are highly crystalline and pure Ag2S nanorods with diameters of 70-160 nm and lengths of 200-360 nm. X-ray diffraction of the S-Ag nanocomposites shows that we obtained cubic Ag and S nanoparticles. Transmission electron microscopy shows that the molar ratio of PVP to Ag+ plays an important role in controlling the size and morphology of the S-Ag nanocomposites. When the molar ratio of PVP to Ag+ was 10:1, smaller sizes, better dispersibility and narrower distribution of S-Ag nanocomposites with diameters of 10-40 nm were obtained. The formation mechanism of the S-Ag nanocomposites was studied by designing a series of experiments using ultraviolet-visible measurement, and it was found that S nanoparticles are produced first and act as seed crystals; then Ag+ becomes Ag nanocrystals on the surfaces of the S nanoparticles by the reduction of PVP. PEG400 acts as a catalyzer, accelerating the reaction rate, and protects the S-Ag nanocomposites from reacting to produce Ag2S. The antimicrobial experiments show that the S-Ag nanocomposites have greater antimicrobial activity on Staphylococcus aureus, Aspergillus niger and blue mold than Ag nanoparticles.

  7. AgI/Ag{sub 3}PO{sub 4} hybrids with highly efficient visible-light driven photocatalytic activity

    SciTech Connect

    Katsumata, Hideyuki; Hayashi, Takahiro; Taniguchi, Masanao; Suzuki, Tohru; Kaneco, Satoshi

    2015-03-15

    Highlights: • AgI/Ag{sub 3}PO{sub 4} hybrid was prepared via an in situ anion-exchange method. • AgI/Ag{sub 3}PO{sub 4} displays the excellent photocatalytic activity under visible light. • AgI/Ag{sub 3}PO{sub 4} readily transforms to be Ag@AgI/Ag{sub 3}PO{sub 4} system. • h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization over AgI/Ag{sub 3}PO{sub 4}. • The activity enhancement is ascribed to a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI. - Abstract: Highly efficient visible-light-driven AgI/Ag{sub 3}PO{sub 4} hybrid photocatalysts with different mole ratios of AgI were prepared via an in situ anion-exchange method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) technique. Under visible light irradiation (>420 nm), the AgI/Ag{sub 3}PO{sub 4} photocatalysts displayed the higher photocatalytic activity than pure Ag{sub 3}PO{sub 4} and AgI for the decolorization of acid orange 7 (AO 7). Among the hybrid photocatalysts, AgI/Ag{sub 3}PO{sub 4} with 80% of AgI exhibited the highest photocatalytic activity for the decolorization of AO 7. X-ray photoelectron spectroscopy (XPS) results revealed that AgI/Ag{sub 3}PO{sub 4} readily transformed to be Ag@AgI/Ag{sub 3}PO{sub 4} system while the photocatalytic activity of AgI/Ag{sub 3}PO{sub 4} remained after 5 recycling runs. In addition, the quenching effects of different scavengers displayed that the reactive h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization. The photocatalytic activity enhancement of AgI/Ag{sub 3}PO{sub 4} hybrids can be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI, in which Ag nanoparticles act as the charge separation center.

  8. The cardiovascular response to the AGS

    NASA Technical Reports Server (NTRS)

    Cardus, David; Mctaggart, Wesley G.

    1993-01-01

    This paper reports the preliminary results of experiments on human subjects conducted to study the cardiovascular response to various g-levels and exposure times using an artificial gravity simulator (AGS). The AGS is a short arm centrifuge consisting of a turntable, a traction system, a platform and four beds. Data collection hardware is part of the communication system. The AGS provides a steep acceleration gradient in subjects in the supine position.

  9. Multiple Partial Siberian Snakes in the AGS

    NASA Astrophysics Data System (ADS)

    Takano, J.; Ahrens, L. A.; Bai, M.; Brown, K.; Courant, E. D.; Gardner, C. J.; Glenn, J. W.; Hattori, T.; Huang, H.; Lin, F.; Luccio, A. U.; MacKay, W. W.; Okamura, M.; Roser, T.; Tepikian, S.; Tsoupas, N.; Yip, K.; Zelenski, A.; Zeno, K.

    2007-06-01

    Polarized protons are accelerated up to 24.3 GeV in the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). To accelerate the beam with preserving the polarization, two different types of helical dipole partial Siberian snake have been installed to the AGS. One is a superconducting magnet (Cold Snake, CSNK), and the other is a normal conducting one (Warm Snake, WSNK). With these snake magnets, the polarization at the AGS extraction achieved 65%. However, the AGS has spin mismatches at the injection and extraction. This description shows calculated results to have better spin matching with using two or three snakes.

  10. Multiple Partial Siberian Snakes in the AGS

    SciTech Connect

    Takano, J.; Ahrens, L. A.; Bai, M.; Brown, K.; Courant, E. D.; Gardner, C. J.; Glenn, J. W.; Huang, H.; Luccio, A. U.; MacKay, W. W.; Okamura, M.; Roser, T.; Tepikian, S.; Tsoupas, N.; Yip, K.; Zelenski, A.; Zeno, K.; Hattori, T.; Lin, F.

    2007-06-13

    Polarized protons are accelerated up to 24.3 GeV in the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). To accelerate the beam with preserving the polarization, two different types of helical dipole partial Siberian snake have been installed to the AGS. One is a superconducting magnet (Cold Snake, CSNK), and the other is a normal conducting one (Warm Snake, WSNK). With these snake magnets, the polarization at the AGS extraction achieved 65%. However, the AGS has spin mismatches at the injection and extraction. This description shows calculated results to have better spin matching with using two or three snakes.

  11. Transformation from Ag@Ag3PO4 to Ag@Ag2SO4 hybrid at room temperature: preparation and its visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Wei, Ting; Gao, Shanmin; Wang, Qingyao; Xu, Hui; Wang, Zeyan; Huang, Baibiao; Dai, Ying

    2017-02-01

    In the present study, Ag/Ag2SO4 hybrid photocatalysts were obtained via a facile redox-precipitation reaction approach by using Ag@Ag3PO4 nanocomposite as the precursor and KMnO4 as the oxidant. Multiple techniques, such as X-ray diffraction pattern (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and Brunauer-Emmett-Teller (BET), photocurrent and electrochemical impedance spectroscopy (EIS), were applied to investigate the structures, morphologies, optical, and electronic properties of as-prepared samples. The photocatalytic activities were evaluated by photodegradation of organic rhodamine B (RhB) and methyl orange (MO) under visible light irradiation. It was found that pure Ag2SO4 can partially transform into metallic Ag during the photocatalytic degradation of organic pollutants, but the Ag/Ag2SO4 hybrids can maintain its structure stability and show enhanced visible light photocatalytic activity because of the surface plasma resonance effect of the metallic Ag.

  12. Toxicokinetics of Ag in the terrestrial isopod Porcellionides pruinosus exposed to Ag NPs and AgNO₃ via soil and food.

    PubMed

    Tourinho, Paula S; van Gestel, Cornelis A M; Morgan, A John; Kille, Peter; Svendsen, Claus; Jurkschat, Kerstin; Mosselmans, J Fred W; Soares, Amadeu M V M; Loureiro, Susana

    2016-03-01

    Silver nanoparticles (Ag NPs) have been used in numerous consumer products and may enter the soil through the land application of biosolids. However, little is known about the relationship between Ag NP exposure and their bioavailability for soil organisms. This study aims at comparing the uptake and elimination kinetics of Ag upon exposures to different Ag forms (NPs and ionic Ag (as AgNO3)) in the isopod Porcellionides pruinosus. Isopods were exposed to contaminated Lufa 2.2 soil or alder leaves as food. Uptake and elimination rate constants for soil exposure did not significantly differ between Ag NPs and ionic Ag at 30 and 60 mg Ag/kg. For dietary exposure, the uptake rate constant was up to 5 times higher for Ag NPs than for AgNO3, but this was related to feeding activity and exposure concentrations, while no difference in the elimination rate constants was found. When comparing both routes, dietary exposure resulted in lower Ag uptake rate constants but elimination rate constants did not differ. A fast Ag uptake was observed from both routes and most of the Ag taken up seemed not to be eliminated. Synchrotron X-ray fluorescence showed Ag in the S-cells of the hepatopancreas, thus supporting the observations from the kinetic experiment (i.e. low elimination). In addition, our results show that isopods have an extremely high Ag accumulation capacity, suggesting the presence of an efficient Ag storage compartment.

  13. Single step electrochemical synthesis of hydrophilic/hydrophobic Ag5 and Ag6 blue luminescent clusters.

    PubMed

    Santiago González, Beatriz; Blanco, M C; López-Quintela, M Arturo

    2012-12-21

    Well-defined Ag(5) and Ag(6) dodecanethiol/tetrabutyl ammonium-protected clusters were prepared by a one-pot electrochemical method. Ag clusters show bright and photostable emissions. The presence of a dual capping renders the silver clusters soluble in both organic and aqueous solvents.

  14. Synthesis of Cu-Ag@Ag particles using hyperbranched polyester as template

    NASA Astrophysics Data System (ADS)

    Han, Wen-Song

    2015-07-01

    In this manuscript, the third-generation hyperbranched polyester was synthesized with 2, 2-dimethylol propionic acid as AB2 monomer and pentaerythrite as core molecule by using step by step polymerization process at first. Then, the Cu-Ag particles were prepared by co-reduction of silver nitrate and copper nitrate with ascorbic acid in the aqueous solution using hyperbranched polyester as template. Finally, the Cu-Ag@Ag particles were prepared by coating silver on the surface of Cu-Ag particles by reduction of silver nitrate. The synthesized hyperbranched polyester and Cu-Ag@Ag particles were characterized by Fourier transform infrared (FT-IR) spectroscopy, UV-vis spectra, x-ray diffraction, Laser light scattering, thermogravimetric analysis (TGA) and SEM. UV-vis spectra results showed that the Cu-Ag@Ag particles had a strong absorption band at around 420 nm. Laser light scattering and SEM studies confirmed that the most frequent particle sizes of Cu-Ag@Ag particles were 1.2 um. TGA results indicated that the Cu-Ag@Ag particles had good thermal stability. [Figure not available: see fulltext.

  15. An Au/AgBr-Ag heterostructure plasmonic photocatalyst with enhanced catalytic activity under visible light.

    PubMed

    Purbia, Rahul; Paria, Santanu

    2017-01-17

    This study reports an easy synthesis protocol of a novel bimetallic silver halide (Au/AgBr-Ag) plasmonic heterostructure as a visible light induced photocatalyst. In this process, first CTAB capped Au NPs were coated with AgBr, and then Ag nanoparticles were formed on the surface of AgBr by photoreduction, while exposing to daylight at room temperature. The presence of Au and Ag improves the visible absorption ability of NPs and avoids charge recombination of the semiconductor AgBr during photoexcitation, which in turn enhances 16 and 8.9 fold the photocatalytic efficiency of Rhodamine B dye degradation under visible light irradiation compared to that of pure AgBr and AgBr/Ag, respectively. The recycling tests of the photocatalyst show only ∼8.7% decrease in efficiency after the 5(th) cycle of reuse without changing the morphology. During the photocatalytic process, active superoxide radicals (O2˙(-)) play a major role, proved through scavenger trapping and photoluminescence experiments. The presence of two plasmonic metals (Au and Ag) in the heterostructure helps to improve visible light absorption as well as avoid charge recombination of the semiconductor AgBr to act as a better photocatalyst. Since this heteronanostructure can be easily synthesized by a one-step method, this study could provide a new approach for the development of efficient bimetallic/semiconductor halide plasmonic photocatalysts with enhanced visible absorption and better charge separation.

  16. Highly efficient visible light plasmonic photocatalyst Ag@Ag(Br,I).

    PubMed

    Wang, Peng; Huang, Baibiao; Zhang, Qianqian; Zhang, Xiaoyang; Qin, Xiaoyan; Dai, Ying; Zhan, Jie; Yu, Jiaoxian; Liu, Haixia; Lou, Zaizhu

    2010-09-03

    The new plasmonic photocatalyst Ag@Ag(Br,I) was synthesized by the ion-exchange process between the silver bromide and potassium iodide, then by reducing some Ag(+) ions in the surface region of Ag(Br,I) particles to Ag(0) species. Ag nanoparticles are formed from Ag(Br,I) by the light-induced chemical reduction reaction. The Ag@Ag(Br,I) particles have irregular shapes with their sizes varying from 83 nm to 1 mum. The as-grown plasmonic photocatalyst shows strong absorption in the visible light region because of the plasmon resonance of Ag nanoparticles. The ability of this compound to reduce Cr(VI) under visible light was compared with those of other reference photocatalyst. The plasmonic photocatalyst is shown to be highly efficient under visible light. The stability of the photocatalyst was examined by X-ray diffraction and X-ray photoelectron spectroscopy. The XRD pattern and XPS spectra prove the stability of the plasmonic photocatalyst Ag@Ag(Br,I).

  17. Negligible shift of 3Ag- potential in longer-chain carotenoids as revealed by a single persistent peak of 3Ag-→1Ag- stimulated emission followed by 3Ag-←1Ag- transient-absorption

    NASA Astrophysics Data System (ADS)

    Li, Chunyong; Miki, Takeshi; Kakitani, Yoshinori; Koyama, Yasushi; Nagae, Hiroyoshi

    2007-12-01

    Upon excitation of lycopene, anhydrorhodovibrin or spirilloxanthin to the 1Bu+(0) state, stimulated emission followed by transient-absorption was observed as a single peak with the 3Ag-(0) energy that had been determined by measurement of resonance-Raman excitation profiles. This observation was explained in terms of negligible shift of the 3Ag- potential, in reference to the 1Ag- potential, where only the 3Ag-(υ)→1Ag-(υ) emission and the 3Ag-(υ)←1Ag-(υ) absorption become allowed during the vibrational relaxation of υ = 2 → 1 → 0, starting from the 3Ag-(2) level generated by diabatic internal conversion from the 1Bu+(0) level, in anhydrorhodovibrin, for example.

  18. Investigation of the role of the NO-cGMP pathway on YC-1 and DEA/NO effects on thoracic aorta smooth muscle responses in a rat preeclampsia model.

    PubMed

    Turgut, Nergiz Hacer; Temiz, Tijen Kaya; Turgut, Bülent; Karadas, Baris; Parlak, Mesut; Bagcivan, Ihsan

    2013-10-01

    The present study was designed to investigate the effects of YC-1, a nitric oxide (NO)-independent soluble guanylate cyclase (sGC) activator, and DEA/NO, a NO donor, on smooth muscle responses in the preeclampsia model with suramin-treated rats and on the levels of cyclic guanosine monophosphate (cGMP) of thoracic aorta rings isolated from term-pregnant rats. Rats of 2 groups, control group and suramin group, were given intraperitoneal injection of saline or suramin, respectively. Suramin injection caused increased blood pressure, protein in urine, and fetal growth retardation. Thoracic aorta rings were exposed to contractile and relaxant agents. KCl contraction and papaverine relaxation responses were similar. Relaxation responses of YC-1 and DEA/NO decreased in suramin group. In both groups in the presence of ODQ, a sGC inhibitor, the relaxation responses of YC-1 and DEA/NO decreased. The cGMP content was determined by radioimmunoassay technique. The content of cGMP in the suramin group decreased. In the presence of YC-1 and DEA/NO in both groups, cGMP content increased, but in ODQ-added groups, there was a significant decrease. We conclude that in preeclampsia, the decrease of relaxation responses and the decrease of cGMP content could be due to the reduction in stimulation of sGC and the decrease in cGMP levels.

  19. Half-life determination for 108Ag and 110Ag

    NASA Astrophysics Data System (ADS)

    Zahn, Guilherme S.; Genezini, Frederico A.

    2014-11-01

    In this work, the half-life of the short-lived silver radionuclides 108Ag and 110Ag were measured by following the activity of samples after they were irradiated in the IEA-R1 reactor. The results were then fitted using a non-paralizable dead time correction to the regular exponential decay and the individual half-life values obtained were then analyzed using both the Normalized Residuals and the Rajeval techniques, in order to reach the most exact and precise final values. To check the validity of dead-time correction, a second correction method was also employed by means of counting a long-lived 60Co radioactive source together with the samples as a livetime chronometer. The final half-live values obtained using both dead-time correction methods were in good agreement, showing that the correction was properly assessed. The results obtained are partially compatible with the literature values, but with a lower uncertainty, and allow a discussion on the last ENSDF compilations' values.

  20. Progress with the AGS Booster

    SciTech Connect

    Weng, W.T.

    1988-01-01

    Rare K-decay, neutrino and heavy ion physics demands that a rapid- cycling high vacuum and high intensity Booster be built for the AGS at Brookhaven. For each mode of operation there are corresponding accelerator physics and design issues needing special attention. Problems pertinent to any single mode of operation have been encountered and solved before, but putting high intensity proton requirements and high vacuum heavy ion requirements into one machine demands careful design considerations and decisions. The lattice design and magnet characteristics will be briefly reviewed. Major design issues will be discussed and design choices explained. Finally, the construction status and schedule will be presented. 6 refs., 6 figs.

  1. Investigation of the vasorelaxant effects of 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1) and diethylamine/nitric oxide (DEA/NO) on the human radial artery used as coronary bypass graft.

    PubMed

    Berkan, Ocal; Bagcivan, Ihsan; Kaya, Tijen; Yildirim, Kemal; Yildirim, Sahin; Doğan, Kasim

    2007-05-01

    The radial artery (RA) is used as a spastic coronary bypass graft. This study was designed to investigate the mechanism of vasorelaxant effects of YC-1 (3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole), a nitric oxide (NO)-independent soluble guanylate cyclase (sGC) activator, and DEA/NO (diethylamine/nitric oxide), a NO-nucleophile adduct, on the human RA. RA segments (n = 25) were obtained from coronary artery bypass grafting patients and were divided into 3-4 mm vascular rings. Using the isolated tissue bath technique, the endothelium-independent vasodilatation function was tested in vitro by the addition of cumulative concentrations of YC-1 (10-10 to 3 x 10-7 mol/L) and DEA/NO (10-8 to 3 x 10-5 mol/L) following vasocontraction by phenylephrine in the presence or absence of 10-5 mol/L ODQ (1H-(1,2,4)oxadiazole(4,3-a)quinoxalin-1-one), the selective sGC inhibitor, 10-7 mol/L iberiotoxin, a blocker of Ca2+-activated K+ channels, or 10-5 mol/L ODQ plus 10-7 mol/L iberiotoxin. We also evaluated the effect of YC-1 and DEA/NO on the cGMP levels in vascular rings obtained from human radial artery (n = 6 for each drug). YC-1 (10-10 to 3 x 10-7 mol/L) and DEA/NO (10-8 to 3 x 10-5 mol/L) caused the concentration-dependent vasorelaxation in RA rings precontracted with phenylephrine (10-5 mol/L) (n = 20 for each drug). Pre-incubation of RA rings with ODQ, iberiotoxin, or ODQ plus iberiotoxin significantly inhibited the vasorelaxant effect of YC-1, but the inhibitor effect of ODQ plus iberiotoxin was significantly more than that of ODQ and iberiotoxin alone (p < 0.05). The vasorelaxant effect of DEA/NO almost completely abolished in the presence of ODQ and iberiotoxin plus ODQ, but did not significantly change in the presence of iberiotoxin alone (p > 0.05). The pEC50 value of DEA/NO was significantly lower than those for YC-1 (p < 0.01), with no change Emax values in RA rings. In addition, YC-1-stimulated RA rings showed more elevation in cGMP than that of DEA/NO (p < 0

  2. Visible light driven photocatalysis and antibacterial activity of AgVO{sub 3} and Ag/AgVO{sub 3} nanowires

    SciTech Connect

    Singh, Anamika; Dutta, Dimple P.; Ballal, A.; Tyagi, A.K.; Fulekar, M.H.

    2014-03-01

    Graphical abstract: - Highlights: • Ag/AgVO{sub 3} and pure AgVO{sub 3} nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO{sub 3} within 45 min. • Antibacterial activity of Ag/AgVO{sub 3} demonstrated. - Abstract: Ag/AgVO{sub 3} nanowires and AgVO{sub 3} nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed that inert atmosphere promotes the formation of Ag/AgVO{sub 3} nanowires. The photocatalytic studies revealed that the Ag/AgVO{sub 3} nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO{sub 3} nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO{sub 3} nanorods prove that in case of the Ag dispersed Ag/AgVO{sub 3} nanowires, the enhanced antibacterial action is also due to contribution from the AgVO{sub 3} support.

  3. Effects of soil and dietary exposures to Ag nanoparticles and AgNO₃ in the terrestrial isopod Porcellionides pruinosus.

    PubMed

    Tourinho, Paula S; van Gestel, Cornelis A M; Jurkschat, Kerstin; Soares, Amadeu M V M; Loureiro, Susana

    2015-10-01

    The effects of Ag-NPs and AgNO3 on the isopod Porcellionides pruinosus were determined upon soil and dietary exposures. Isopods avoided Ag in soil, with EC50 values of ∼16.0 and 14.0 mg Ag/kg for Ag-NPs and AgNO3, respectively. Feeding inhibition tests in soil showed EC50s for effects on consumption ratio of 127 and 56.7 mg Ag/kg, respectively. Although similar EC50s for effects on biomass were observed for nanoparticulate and ionic Ag (114 and 120 mg Ag/kg dry soil, respectively), at higher concentrations greater biomass loss was found for AgNO3. Upon dietary exposure, AgNO3 was more toxic, with EC50 for effects on biomass change being >1500 and 233 mg Ag/kg for Ag-NPs and AgNO3, respectively. The difference in toxicity between Ag-NPs and AgNO3 could not be explained from Ag body concentrations. This suggests that the relation between toxicity and bioavailability of Ag-NPs differs from that of ionic Ag in soils.

  4. Photocatalytic oxidation removal of Hg0 using ternary Ag/AgI-Ag2CO3 hybrids in wet scrubbing process under fluorescent light

    NASA Astrophysics Data System (ADS)

    Zhang, Anchao; Zhang, Lixiang; Chen, Xiaozhuan; Zhu, Qifeng; Liu, Zhichao; Xiang, Jun

    2017-01-01

    A series of ternary Ag/AgI-Ag2CO3 photocatalysts synthesized using a facile coprecipitation method were employed to investigate their performances of Hg0 removal in a wet scrubbing reactor. The hybrids were characterized by N2 adsorption-desorption, XRD, SEM-EDS, HRTEM, XPS, DRS and ESR. The photocatalytic activities of Hg0 removal were evaluated under fluorescent light. The results showed that AgI content, fluorescent light irradiation, reaction temperature all showed significant influences on Hg0 removal. NO exhibited significant effect on Hg0 removal in comparison to SO2. Among these ternary Ag/AgI-Ag2CO3 hybrids, Ag/AgI(0.1)-Ag2CO3 showed the highest Hg0 removal efficiency, which could be ascribed to the effective separation of photogenerated electron-hole pairs between AgI and Ag2CO3 and the surface plasmon resonance (SPR) effect in the visible region by metallic silver nanoparticles (Ag0 NPs). The trapping studies of reactive radicals showed that the superoxide radicals (rad O2-) may play a key role in Hg0 removal under fluorescent light. According to the experimental and characterization results, a possible photocatalytic oxidation mechanism for enhanced Hg0 removal over Ag/AgI(0.1)-Ag2CO3 hybrid under fluorescent light was proposed.

  5. A Study of the Strategic Alliance for EMS Industry: The Application of a Hybrid DEA and GM (1, 1) Approach

    PubMed Central

    Wang, Chia Nan; Tran, Thanh Tuyen; Huong, Bui Bich

    2015-01-01

    Choosing a partner is a critical factor for success in international strategic alliances, although criteria for partner selection vary between developed and transitional markets. This study aims to develop effective methods to assist enterprise to measure the firms' operation efficiency, find out the candidate priority under several different inputs and outputs, and forecast the values of those variables in the future. The methodologies are constructed by the concepts of Data Envelopment Analysis (DEA) and grey model (GM). Realistic data in four consecutive years (2009–2012) a total of 20 companies of the Electronic Manufacturing Service (EMS) industry that went public are completely collected. This paper tries to help target company—DMU1—to find the right alliance partners. By our proposed approach, the results show the priority in the recent years. The research study is hopefully of interest to managers who are in manufacturing industry in general and EMS enterprises in particular. PMID:25821859

  6. [Efficiency of Brazilian States and the Federal District in the public kidney transplant system based on DEA (Data Envelopment Analysis) and the Malmquist index].

    PubMed

    Costa, Cassia Kely Favoretto; Balbinotto Neto, Giácomo; Sampaio, Luciano Menezes Bezerra

    2014-08-01

    The objective of this study was to evaluate the efficiency of Brazilian States and the Federal District in the public kidney transplant system and their productivity trends from 2006 to 2011. The authors used Data Envelopment Analysis (DEA) with slack and the Malmquist index with slack. Inputs included spending on hospital services and health professionals in the system. The output was the number of kidney transplants performed in each State. The data showed a significant discrepancy between States in the number of kidney transplants. The transplant system's inefficiency may result from inadequate management, failure to comply with national guidelines, inactive hospital transplant committees, and overburdened hospital staff. Institutional changes promoted by the Brazilian Ministry of Health (procedures improvement and standardization) failed to increase productivity in most States during this period.

  7. AgRISTARS documents tracking list report

    NASA Technical Reports Server (NTRS)

    Hawkins, J. L.

    1983-01-01

    A quarterly listing of documents issued and placed in the AgRISTARS tracking system is provided. The technical publications are arranged by type of documents. The reference AgRISTARS document number, title and date of publication, the issuing organization, and the National Technical Information Service reference number is given.

  8. The AGS synchrotron with four helical magnets

    SciTech Connect

    Tsoupas N.; Huang, H.; Roser, T.; MacKay, W.W.; Trbojevic, D.

    2012-05-20

    The idea of using two partial helical magnets was applied successfully to the AGS synchrotron to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. The placement of four helical magnets in the AGS ring provides many advantages over the present setup of the AGS which uses two partial helical magnets. First, the symmetric placement of the four helical magnets allows for a better control of the AGS optics with reduced values of the beta functions especially near beam injection, second, the vertical spin direction during beam injection and extraction is closer to vertical, and third, it provides for a larger 'spin tune gap', which allows the vertical and horizontal tunes to be placed, and prevent the horizontal and vertical intrinsic spin resonances of the AGS to occur during the acceleration cycle. Although the same spin gap can be obtained with a single or two partial helices, the required high field strength of a single helix makes its use impractical, and that of the double helix rather difficult. In this paper we will provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and compare these results with the present setup of the AGS that uses two partial helical magnets.

  9. AgPO2F2 and Ag9(PO2F2)14: the first Ag(i) and Ag(i)/Ag(ii) difluorophosphates with complex crystal structures.

    PubMed

    Malinowski, Przemysław J; Kurzydłowski, Dominik; Grochala, Wojciech

    2015-12-07

    The reaction of AgF2 with P2O3F4 yields a mixed valence Ag(I)/Ag(II) difluorophosphate salt with AgAg(PO2F2)14 stoichiometry - the first Ag(ii)-PO2F2 system known. This highly moisture sensitive brown solid is thermally stable up to 120 °C, which points at further feasible extension of the chemistry of Ag(ii)-PO2F2 systems. The crystal structure shows a very complex bonding pattern, comprising of polymeric Ag(PO2F2)14(4-) anions and two types of Ag(I) cations. One particular Ag(II) site present in the crystal structure of Ag9(PO2F2)14 is the first known example of square pyramidal penta-coordinated Ag(ii) in an oxo-ligand environment. Ag(i)PO2F2 - the product of the thermal decomposition of Ag9(PO2F2)14 - has also been characterized by thermal analysis, IR spectroscopy and X-ray powder diffraction. It has a complicated crystal structure as well, which consists of infinite 1D [Ag(I)O4/2] chains which are linked to more complex 3D structures via OPO bridges. The PO2F2(-) anions bind to cations in both compounds as bidentate oxo-ligands. The terminal F atoms tend to point inside the van der Waals cavities in the crystal structure of both compounds. All important structural details of both title compounds were corroborated by DFT calculations.

  10. Ligand and counterion control of Ag(I) architectures: assembly of a {Ag8} ring cluster mediated by hydrophobic and Ag...Ag interactions.

    PubMed

    Fielden, John; Long, De-liang; Slawin, Alexandra M Z; Kögerler, Paul; Cronin, Leroy

    2007-10-29

    A strategy combining ligand design and counterion variation has been used to investigate the assembly of silver(I) complexes. As a result, dinuclear, octanuclear, and polymeric silver(I) species have been synthesized by complexation of the rigid aliphatic amino ligands cis-3,5-diamino-trans-hydroxycyclohexane (DAHC), cis-3,5-diamino-trans-methoxycyclohexane (DAMC), and cis-3,5-diamino-trans-tert-butyldimethylsilylanyloxycyclohexane (DATC) with silver(I) triflate, nitrate, and perchlorate. The compositions of these aggregates, established by X-ray crystallography and elemental analysis, are [{Ag(DAHC)}2](CF3SO3)2 (1), [{Ag(DAMC)}2](CF3SO3)2 (2), [{Ag(DAMC)}2](NO3)2 (3), [{Ag(DATC)}6{Ag(DAHC)}2](NO3)8 (4), and [{Ag(DATC}n](NO3)n (5), where the DAHC present in 4 is formed by in situ hydrolysis of the acid labile silyl ether group. The type of aggregate formed depends both upon the noncoordinating O-substituent of the ligand and the (also noncoordinating) counterion, with the normal preference of the ligand topology for forming Ag2L2 structures being broken by introduction of the bulky, lipophilic O-tert-butyldimethylsilyl (TBDMS) group. Of particular note is the octanuclear silver ring structure 4, which is isolated only when both the O-TBDMS group and the nitrate counteranion are present and is formed from four Ag2L2 dimers connected by Ag...Ag and hydrogen-bonding interactions. Diffusion rate measurement of this {Ag8} complex by 1H NMR (DOSY) indicates dissociation in CD3OD and CD3CN, showing that this supramolecular ring structure is formed upon crystallization, and establishing a qualitative limit to the strength of Ag...Ag interactions in solution. When solutions of the {Ag8} cluster in methanol are kept for several days though, a new UV-vis absorption is observed at around 430 nm, consistent with the formation of silver nanoparticles.

  11. Fluorescent DNA-bound Ag nanoclusters

    NASA Astrophysics Data System (ADS)

    O'Neill, Patrick; Velazquez, Lourdes; Weirich, Kim; Fygenson, Deborah

    2009-03-01

    Few-atom fluorescent Ag nanoclusters self-assemble on short, synthetic DNA strands, and exhibit sequence and structure dependent fluorescence ranging from the blue to the near infrared. Here we report UV excitation as a ubiquitous feature of these emitters. Each emitter thus has two excitation peaks: a visible peak which is cluster-dependent, and a UV peak which has the same wavelength for all DNA-bound Ag clusters. This UV peak corresponds to resonant absorbance by the DNA bases, and produces the same emission spectra as visible excitation, suggesting energy transfer from the DNA bases to the Ag cluster. We make use of this UV excitation to image the emitters in unstained polyacrylamide gels, and show that electrophoresis can be used to create a pure solution of green DNA:Ag11 clusters from an inhomogeneous red solution of DNA:Ag>12 clusters.

  12. Direct electrospinning of Ag/polyvinylpyrrolidone nanocables

    NASA Astrophysics Data System (ADS)

    Song, Jie; Chen, Menglin; Olesen, Mikkel Buster; Wang, Chenxuan; Havelund, Rasmus; Li, Qiang; Xie, Erqing; Yang, Rong; Bøggild, Peter; Wang, Chen; Besenbacher, Flemming; Dong, Mingdong

    2011-12-01

    Core-sheath silver nanowire/polyvinylpyrrolidone (AgNW/PVP) nanocables have been fabricated via an efficient single-spinneret electrospinning method. The core-sheath structure is revealed by combining several characterization methods. A possible formation mechanism of the AgNW/PVP nanocable involving a strong stretching during the electrospinning process is proposed. Further, electrical measurements were performed on AgNW/PVP nanocables as well as bare AgNWs, which indicated the nanocables became insulating due to the isolation of highly conductive AgNWs by insulating PVP sheath. Therefore, the described fabrication method holds potential for the fabrication of low-cost metal/polymer composite materials for nanoelectronic applications in general.

  13. Antibacterial biodegradable Mg-Ag alloys.

    PubMed

    Tie, D; Feyerabend, F; Müller, W D; Schade, R; Liefeith, K; Kainer, K U; Willumeit, R

    2013-06-16

    The use of magnesium alloys as degradable metals for biomedical applications is a topic of ongoing research and the demand for multifunctional materials is increasing. Hence, binary Mg-Ag alloys were designed as implant materials to combine the favourable properties of magnesium with the well-known antibacterial property of silver. In this study, three Mg-Ag alloys, Mg2Ag, Mg4Ag and Mg6Ag that contain 1.87 %, 3.82 % and 6.00 % silver by weight, respectively, were cast and processed with solution (T4) and aging (T6) heat treatment. The metallurgical analysis and phase identification showed that all alloys contained Mg4Ag as the dominant β phase. After heat treatment, the mechanical properties of all Mg-Ag alloys were significantly improved and the corrosion rate was also significantly reduced, due to presence of silver. Mg(OH)₂ and MgO present the main magnesium corrosion products, while AgCl was found as the corresponding primary silver corrosion product. Immersion tests, under cell culture conditions, demonstrated that the silver content did not significantly shift the pH and magnesium ion release. In vitro tests, with both primary osteoblasts and cell lines (MG63, RAW 264.7), revealed that Mg-Ag alloys show negligible cytotoxicity and sound cytocompatibility. Antibacterial assays, performed in a dynamic bioreactor system, proved that the alloys reduce the viability of two common pathogenic bacteria, Staphylococcus aureus (DSMZ 20231) and Staphylococcus epidermidis (DSMZ 3269), and the results showed that the killing rate of the alloys against tested bacteria exceeded 90%. In summary, biodegradable Mg-Ag alloys are cytocompatible materials with adjustable mechanical and corrosion properties and show promising antibacterial activity, which indicates their potential as antibacterial biodegradable implant materials.

  14. Photo- and thermo-chemical transformation of AgCl and Ag2S in environmental matrices and its implication.

    PubMed

    Yin, Yongguang; Xu, Wei; Tan, Zhiqiang; Li, Yanbin; Wang, Weidong; Guo, Xiaoru; Yu, Sujuan; Liu, Jingfu; Jiang, Guibin

    2017-01-01

    AgCl and Ag2S prevalently exist in the environment as minerals and/or the chlorination and sulfidation products of ionic silver and elemental silver nanoparticles (AgNPs). In this work, we investigated the chemical transformation of AgCl and Ag2S under simulated sunlight (in water) and incineration (in sludge and simulated municipal solid waste, SMSW). In the presence of natural organic matter, AgCl in river water was observed to be transformed into AgNPs under simulated sunlight, while photo-reduction of Ag2S could not take place under the same experimental conditions. During the course of incineration, pure Ag2S was transformed into elemental silver while AgCl remained stable; however, both Ag2S in sludge and AgCl in SMSW can be transformed to elemental silver under incineration, evident by the results of X-ray absorption spectroscopy and scanning electron microscopy measurements. Incineration temperature played an important role in the transformation of Ag2S and AgCl into elemental silver. These results suggest that chemical transformations of Ag2S and AgCl into elemental silver could be a possible source of naturally occurring or unintentionally produced AgNPs, affecting the fate, transport, bioavailability and toxicity of silver. Therefore, it is necessary to include the contributions of this transformation process when assessing the risk of ionic silver/AgNPs and the utilization and management of incineration residues.

  15. Formation of AgGaS2 nano-pyramids from Ag2S nanospheres through intermediate Ag2S-AgGaS2 heterostructures and AgGaS2 sensitized Mn2+ emission.

    PubMed

    Huang, Feng; Zhou, Jiangcong; Xu, Ju; Wang, Yuansheng

    2014-02-21

    A one-pot solution synthesis of monodisperse AgGaS2 nanocrystals with uniform pyramid-like shape is realized for the first time, in which an interesting phase and shape evolution from monodisperse Ag2S nanospheres to pure AgGaS2 nano-pyramids through an intermediate stage of Ag2S-AgGaS2 heterostructures, is revealed. Evidently, upon introducing Mn(2+) ions into the reaction system, they are incorporated into AgGaS2 nano-pyramids which act as efficient sensitization matrixes for the red emission of Mn(2+) d-d transition under blue excitation. Benefiting from their non-toxicity and facile fabrication, Mn:AgGaS2 nanocrystals may find potential applications in some fields such as blue chip excited LEDs and bio-labeling.

  16. AgS2O6CF3: the first trifluoromethylsulfonylsulfate(VI).

    PubMed

    Malinowski, Przemysław J; Derzsi, Mariana; Grochala, Wojciech

    2013-08-07

    We describe the synthetic route towards a novel class of salts, trifluoromethylsulfonylsulfates, as exemplified by the silver(I) derivative (AgS2O6CF3). Formation proceeds via direct reaction between a triflate precursor, AgSO3CF3, and SO3. The title compound crystallizes in the P2(1)/c unit cell with a = 5.15746(14) Å, b = 25.8563(9) Å, c = 5.53970(14) Å and β = 101.1749(19)°. The structure is layered with the puckered [AgS2O6] 2D sheets; the terminal CF3 groups are separated by the van der Waals gap, as seen also for related metal triflates. The compound is very fragile thermally and it decomposes endothermally to AgSO3CF3 with concomitant evolution of SO3 even at 65 °C or upon grinding in an agate mortar; thus it may serve as a solid store of--otherwise volatile and corrosive--SO3. The IR and Raman spectra of AgS2O6CF3 have been tentatively assigned based on similarities to those of related Ag2S2O7 and AgSO3CF3 and phonon calculations. Synthesis and properties of KS2O6CF3 are also briefly described.

  17. On the measurement of /sup 107/Ag//sup 109/Ag ratios in meteorites

    SciTech Connect

    Kutschera, W.; Faestermann, T.; Gillitzer, A.; Fortuna, G.

    1986-01-01

    The detection of stable Ag isotopes in meteorites at the ppB level was attempted in an AMS experiment using the Munich MP tandem accelerator in conjunction with a time-of-flight detection system. The sensitivity of detecting Ag at this level was established by observing a counting rate of 17 ions of /sup 107/Ag per sec from a Au sample, which had been spiked with the radioisotope /sup 105/Ag (T/sub 1/2/ = 41 d) at a concentration of 1.0 ppB. A blank Ta sample gave no /sup 105/Ag counts in 13 min, which corresponds to a detection limit of 7.5 x 10/sup -5/ ppB. Although this sensitivity was clearly sufficient to perform /sup 107/Ag and /sup 109/Ag measurements in the desired concentration range, experiments with these isotopes were hampered by a currently irreducable background of stable Ag in the ppM range, possibly originating from the ion source itself. Indications of extraordinarily high Ag concentrations, far above this background, were observed in some of the investigated meteorites, but conclusions on their actual existence must await a better understanding of the origin of the general Ag background. 10 refs., 4 figs., 3 tabs.

  18. Study of antibacterial activity of Ag and Ag2CO3 nanoparticles stabilized over montmorillonite

    NASA Astrophysics Data System (ADS)

    Sohrabnezhad, Sh.; Pourahmad, A.; Mehdipour Moghaddam, M. J.; Sadeghi, A.

    2015-02-01

    Silver carbonate and silver nanoparticles (NPs) over of stabilizer montmorillonite (MMT) have been synthesized in aqueous and polyol solvent, respectively. Dispersions of silver nanoparticles have been prepared by the reduction of silver nitrate over of MMT in presence and absence of Na2CO3 compound in ethylene glycol. It was observed that montmorillonite was capable of stabilizing formed Ag nanoparticles through the reduction of Ag+ ions in ethylene glycol. Na2CO3 was used as carbonate source in synthesis of Ag2CO3 NPs in water solvent and also for controlling of Ag nanoparticles size in ethylene glycol medium. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and ultraviolet-visible diffuse reflectance spectroscopy (DRS). The TEM images showed that Ag NPs size in presence Na2CO3 salts was smaller than without that. The results indicated intercalation of Ag and Ag2CO3 nanoparticles into the montmorillonite clay layers. The diffuse reflectance spectra exhibited a strong surface plasmon resonance (SPR) adsorption peak in the visible region, resulting from Ag nanoparticles. The antibacterial testing results showed that the Ag2CO3-MMT nanocomposite exhibited an antibacterial activity higher than Ag-MMT sample against Escherichia coli.

  19. Hierarchically plasmonic photocatalysts of Ag/AgCl nanocrystals coupled with single-crystalline WO3 nanoplates

    NASA Astrophysics Data System (ADS)

    Chen, Deliang; Li, Tao; Chen, Qianqian; Gao, Jiabing; Fan, Bingbing; Li, Jian; Li, Xinjian; Zhang, Rui; Sun, Jing; Gao, Lian

    2012-08-01

    The hierarchical photocatalysts of Ag/AgCl@plate-WO3 have been synthesized by anchoring Ag/AgCl nanocrystals on the surfaces of single-crystalline WO3 nanoplates that were obtained via an intercalation and topochemical approach. The heterogeneous precipitation process of the PVP-Ag+-WO3 suspensions with a Cl- solution added drop-wise was developed to synthesize AgCl@WO3 composites, which were then photoreduced to form Ag/AgCl@WO3 nanostructures in situ. WO3 nanocrystals with various shapes (i.e., nanoplates, nanorods, and nanoparticles) were used as the substrates to synthesize Ag/AgCl@WO3 photocatalysts, and the effects of the WO3 contents and photoreduction times on their visible-light-driven photocatalytic performance were investigated. The techniques of TEM, SEM, XPS, EDS, XRD, N2 adsorption-desorption and UV-vis DR spectra were used to characterize the compositions, phases and microstructures of the samples. The RhB aqueous solutions were used as the model system to estimate the photocatalytic performance of the as-obtained Ag/AgCl@WO3 nanostructures under visible light (λ >= 420 nm) and sunlight. The results indicated that the hierarchical Ag/AgCl@plate-WO3 photocatalyst has a higher photodegradation rate than Ag/AgCl, AgCl, AgCl@WO3 and TiO2 (P25). The contents and morphologies of the WO3 substrates in the Ag/AgCl@plate-WO3 photocatalysts have important effects on their photocatalytic performance. The related mechanisms for the enhancement in visible-light-driven photodegradation of RhB molecules were analyzed.The hierarchical photocatalysts of Ag/AgCl@plate-WO3 have been synthesized by anchoring Ag/AgCl nanocrystals on the surfaces of single-crystalline WO3 nanoplates that were obtained via an intercalation and topochemical approach. The heterogeneous precipitation process of the PVP-Ag+-WO3 suspensions with a Cl- solution added drop-wise was developed to synthesize AgCl@WO3 composites, which were then photoreduced to form Ag/AgCl@WO3 nanostructures in

  20. The AGS with four helical magnets

    SciTech Connect

    Tsoupas, N.; Huang, H.; MacKay, W.W.; Roser, T.; Trbojevic, D.

    2010-02-25

    The idea of using multiple partial helical magnets was applied successfully to the AGS synchrotron, to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. This modification provides many advantages over the present setup of the AGS that uses two partial helical magnets. First, it provides a larger 'spin tune gap' for the placement of the vertical betatron tune of the AGS during acceleration, second, the vertical spin direction during the beam injection and extraction is closer to vertical, third, the symmetric placement of the snakes allows for a better control of the AGS optics, and for reduced values of the beta and eta functions, especially near injection, fourth, the optical properties of the helical magnets also favor the placement of the horizontal betatron tune in the 'spin tune gap', thus eliminating the horizontal spin resonances. In this paper we provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and we compare these results with the present setup of the AGS that uses two partial helical magnets.

  1. 78 FR 12407 - Self-Regulatory Organizations; ICE Clear Credit LLC; Order Approving Proposed Rule Change To Add...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-22

    ... Telecom International Finance B.V.; RWE Aktiengesellschaft; TELECOM ITALIA SPA; TELEFONICA, S.A.; Telekom... Aktiebolag; VEOLIA ENVIRONNEMENT; VIVENDI; VODAFONE GROUP PUBLIC LIMITED COMPANY; Deutsche Post AG; European...; Glencore International AG; Henkel AG & Co. KGaA; Koninklijke DSM N.V.; LANXESS Aktiengesellschaft;...

  2. Ion-exchange synthesis of Ag/Ag2S/Ag3CuS2 ternary hollow microspheres with efficient visible-light photocatalytic activity.

    PubMed

    Xing, Chaosheng; Zhang, Yuan; Wu, Zhudong; Jiang, Deli; Chen, Min

    2014-02-21

    Ternary Ag/Ag2S/Ag3CuS2 hollow microspheres were synthesized via an in situ ion-exchange method using Cu7S4 hollow submicrospheres as the template. The as-obtained Ag/Ag2S/Ag3CuS2 composite exhibited a well-defined uniform hollow microsphere morphology with an average diameter of about 1.3 μm. The photocatalytic property of the as-prepared Ag/Ag2S/Ag3CuS2 hollow microsphere composite was investigated by the decomposition of methyl orange (MO) under visible light irradiation (λ > 420 nm). It was shown that the photocatalytic activity of the Ag/Ag2S/Ag3CuS2 hollow microsphere was higher than those of Ag/Ag2S, Cu2O, Cu7S4 and P25 for the photodegradation of MO under visible light irradiation. Radical scavenger experiments demonstrated that superoxide radicals and holes were the main reactive species for MO degradation.

  3. Agent planning in AgScala

    NASA Astrophysics Data System (ADS)

    Tošić, Saša; Mitrović, Dejan; Ivanović, Mirjana

    2013-10-01

    Agent-oriented programming languages are designed to simplify the development of software agents, especially those that exhibit complex, intelligent behavior. This paper presents recent improvements of AgScala, an agent-oriented programming language based on Scala. AgScala includes declarative constructs for managing beliefs, actions and goals of intelligent agents. Combined with object-oriented and functional programming paradigms offered by Scala, it aims to be an efficient framework for developing both purely reactive, and more complex, deliberate agents. Instead of the Prolog back-end used initially, the new version of AgScala relies on Agent Planning Package, a more advanced system for automated planning and reasoning.

  4. SPIN MATCHING FROM AGS TO RHIC.

    SciTech Connect

    MACKAY,W.W.; TSOUPAS,N.

    2002-11-06

    With a partial Siberian snake in the AGS and transport lines with interspersed horizontal and vertical bends, the incoming spin direction at the injection points of both the collider rings is not likely to match the ideal vertical stable spin direction of RHIC which has two full helical Siberian snakes per ring. In this paper we examine the matching of a polarized beam transferred from the AGS into RHIC. The present 5% partial solenoidal snake as well as a proposed 20% superconducting helical are considered for the AGS. Solutions with retuned snakes in RHIC to better match the incoming beam have been found.

  5. Ozone decomposition on Ag/SiO2 and Ag/clinoptilolite catalysts at ambient temperature.

    PubMed

    Nikolov, Penko; Genov, Krassimir; Konova, Petya; Milenova, Katya; Batakliev, Todor; Georgiev, Vladimir; Kumar, Narendra; Sarker, Dipak K; Pishev, Dimitar; Rakovsky, Slavcho

    2010-12-15

    Silver modified zeolite (Bulgarian natural clinoptilolite) and Ag/silica catalysts were synthesized by ion exchange and incipient wet impregnation method respectively and characterized by different techniques. DC arc-AES was used for Ag detection. XRD spectra show that Ag is loaded over the surface of the SiO(2) sample and that after the ion-exchange process the HEU type structure of clinoptilolite is retained. UV-VIS (specific reflection at 310 nm) and IR (band at 695 cm(-1)) spectroscopy analysis proved that silver is loaded as a T-atom into zeolite channels as Ag(+), instead of Na(+), Ca(2+), or K(+) ions, existing in the natural clinoptilolite form. The samples Ag/SiO(2) and Ag-clinoptilolite were tested as catalysts for decomposition of gas phase ozone. Very high catalytic activity (up to 99%) was observed and at the same time the catalysts remained active over time at room temperature.

  6. Control and performance of the AGS and AGS Booster Main Magnet Power Supplies

    SciTech Connect

    Reece, R.K.; Casella, R.; Culwick, B.; Geller, J.; Marneris, I.; Sandberg, J.; Soukas, A.; Zhang, S.Y.

    1993-01-01

    Techniques for precision control of the main magnet power supplies for the AGS and AGS Booster synchrotron will be discussed. Both synchrotrons are designed to operate in a Pulse-to-Pulse Modulation (PPM) environment with a Supercycle Generator defining and distributing global timing events for the AGS Facility. Details of modelling, real-time feedback and feedforward systems, generation and distribution of real time field data, operational parameters and an overview of performance for both machines are included.

  7. Control and performance of the AGS and AGS Booster Main Magnet Power Supplies

    SciTech Connect

    Reece, R.K.; Casella, R.; Culwick, B.; Geller, J.; Marneris, I.; Sandberg, J.; Soukas, A.; Zhang, S.Y.

    1993-06-01

    Techniques for precision control of the main magnet power supplies for the AGS and AGS Booster synchrotron will be discussed. Both synchrotrons are designed to operate in a Pulse-to-Pulse Modulation (PPM) environment with a Supercycle Generator defining and distributing global timing events for the AGS Facility. Details of modelling, real-time feedback and feedforward systems, generation and distribution of real time field data, operational parameters and an overview of performance for both machines are included.

  8. Effects of Ag on the Kirkendall void formation of Sn-xAg/Cu solder joints

    NASA Astrophysics Data System (ADS)

    Kim, Sunghwan; Yu, Jin

    2010-10-01

    Binary Sn-Ag solders with varying amounts of Ag (0.5, 2.0, and 3.5 wt %) were reacted with Cu under bump metallurgy (UBM) which was electroplated with bis-sodium sulfopropyl-disulfide additive, and the characteristics of Kirkendall void formation at the solder joints were investigated. The results indicate that the propensity to form Kirkendall voids at the solder joint decreased with the Ag content. Subsequent Auger electron spectroscopy analyses showed that Ag dissolved in the Cu UBM reduced the segregation of S to the Cu3Sn/Cu interface, which suppressed the nucleation of Kirkendall voids at the interface.

  9. Nanoporous Ag prepared from the melt-spun Cu-Ag alloys

    NASA Astrophysics Data System (ADS)

    Li, Guijing; Song, Xiaoping; Sun, Zhanbo; Yang, Shengchun; Ding, Bingjun; Yang, Sen; Yang, Zhimao; Wang, Fei

    2011-07-01

    Nanoporous Ag ribbons with different morphology and porosity were achieved by the electrochemical corrosion of the melt-spun Cu-Ag alloys. The Cu-rich phase in the alloys was removed, resulting in the formation of the nanopores distributed across the whole ribbon. It is found that the structures, morphology and porosity of the nanoporous Ag ribbons were dependent on the microstructures of the parent alloys. The most of ligaments presented a rod-like shape due to the formation of pseudoeutectic microstructure in the melt-spun Cu 55Ag 45 and Cu 70Ag 30 alloys. For nanoporous Ag prepared from Cu 85Ag 15 alloys, the ligaments were camber-like because of the appearance of the divorced microstructures. Especially, a novel bamboo-grove-like structure could be observed at the cross-section of the nanoporous Ag ribbons. The experiment reveals that nanoporous Ag ribbons exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) effect, but a slight difference existed due to the discrepancy of their morphology.

  10. Lesson 3: Attorney General (AG) Certification

    EPA Pesticide Factsheets

    The AG Certification is a letter confirming legal authority to implement the electronic reporting covered by the application and enforce the affected programs using the electronic documents received under those programs.

  11. AgRISTARS documents tracking list report

    NASA Technical Reports Server (NTRS)

    Hawkins, J. L.

    1982-01-01

    A quarterly listing of those documents and related publications that have been issued and placed in the AgRISTARS tracking system is presented. The Tracking List Report provides a catalog, by project, of technical publications arranged by type of document and gives the reference AgRISTARS document numbers, title and date of publication, the issuing organization, and the National Technical Information Service reference number.

  12. BNL AGS - a context for kaon factories

    SciTech Connect

    Littenberg, L.S.

    1983-05-01

    Figure 1 shows the Brookhaven site with the AGS-CBA complex highlighted. In this photograph the AGS is dwarfed by CBA and indeed during the past few years future plans for particle physics at BNL have been dominated by this enormous project. However, very recently interest in future physics use of the AGS has undergone a strong revival. Indeed, since the beginning of this year, two projects for augmenting the AGS have been proposed. Such projects could keep the AGS viable as a research machine for many years to come. In general such schemes will also improve the performance and increase the versatility of the CBA, and so are doubly valuable. It should be kept in mind that in spite of the fact the AGS has been perhaps the most fruitful machine in the history of high energy physics, its full capacities have never been exploited. Even without improvements at least one generation of rare K decay experiments beyond those currently launched seems feasible. Beyond that a major effort at any of the experiments discussed above could take it to the point where it would be limited by intrinsic physics background. To pursue a full program of physics at this level one would want to increase the intensity of the AGS as described. A ten-fold increase in K flux would remove such experiments from the category of all-out technological assaults and render them manageable by reasonably small groups of physicists. In addition, certain other, cleaner experiments, e.g., K/sub L//sup 0/ ..-->.. e/sup +/e/sup -/ or e/sup +/e/sup -/..pi../sup 0/, could be pushed to limits unobtainable at the present AGS. The increased flux would also be welcomed by the neutrino and hypernuclear physics programs. Even experiments which do not at present require higher fluxes would benefit through the availability of purer beams and cleaner conditions.

  13. 20% PARTIAL SIBERIAN SNAKE IN THE AGS.

    SciTech Connect

    Huang, H; Bai, M; Brown, K A; Glenn, W; Luccio, A U; Mackay, W W; Montag, C; Ptitsyn, V; Roser, T; Tsoupas, N; Zeno, K; Ranjbar, V; Spinka, H; Underwood, D

    2002-11-06

    An 11.4% partial Siberian snake was used to successfully accelerate polarized proton through a strong intrinsic depolarizing spin resonance in the AGS. No noticeable depolarization was observed. This opens up the possibility of using a 20% to 30% partial Siberian snake in the AGS to overcome all weak and strong depolarizing spin resonances. Some design and operation issues of the new partial Siberian snake are discussed.

  14. AGS polarized proton operation in run 8.

    SciTech Connect

    Huang,H.; Ahrens, L.; Bai, M.; Brown, K.A.; Gardner, C.; Glenn, J.W.; Lin, F.; Luccio, A.U.; MacKay, W.W.; Roser, T.; Tepikian, S.; Tsoupas, N.; Yip, K.; Zeno, K.

    2008-06-23

    Dual partial snake scheme has been used for the Brookhaven AGS (Alternating Gradient Synchrotron) polarized proton operation for several years. It has provided polarized proton beams with 1.5 x 10{sup 11} intensity and 65% polarization for RHIC spin program. There is still residual polarization loss. Several schemes such as putting horizontal tune into the spin tune gap, and injection-on-the-fly were tested in the AGS to mitigate the loss. This paper presents the experiment results and analysis.

  15. Dealloying-driven synthesis and characterization of AgCl/Ag/TiO2 nanocomposites with enhanced photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Wang, Tongyang; Wang, Yan; Zhao, Zhengfeng; Zhang, Lanxiang; Huang, Shifeng

    2017-03-01

    The combination of dealloying with acid treatment was used to fabricate mesoporous anatase TiO2 with high specific surface area of 233 m2/g. Using anatase TiO2 as a matrix, a photoreduction strategy was developed to synthesize AgCl/Ag/TiO2 nanocomposites with different Ti/Ag molar ratios. The morphology and properties of AgCl/Ag/TiO2 nanocomposites were investigated by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. The AgCl/Ag/TiO2 nanocomposites showed an enhanced photocatalytic activity for the degradation of methyl orange solution under visible light irradiation. The optimum Ti/Ag molar ratio in the AgCl/Ag/TiO2 nanocomposites was shown to be 6:1, which was attributed to its high specific surface area of 207 m2/g and the surface plasmon resonance effect.

  16. A visible-light-driven core-shell like Ag2S@Ag2CO3 composite photocatalyst with high performance in pollutants degradation.

    PubMed

    Yu, Changlin; Wei, Longfu; Zhou, Wanqin; Dionysiou, Dionysios D; Zhu, Lihua; Shu, Qing; Liu, Hong

    2016-08-01

    A series of Ag2S-Ag2CO3 (4%, 8%, 16%, 32% and 40% Ag2S), Ag2CO3@Ag2S (32%Ag2S) and Ag2S@Ag2CO3 (32%Ag2S) composite photocatalysts were fabricated by coprecipitation or successive precipitation reaction. The obtained catalysts were analyzed by N2 physical adsorption, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and photocurrent test. Under visible light irradiation, the influences of Ag2S content and core-shell property on photocatalytic activity and stability were evaluated in studies focused on the degradation of methyl orange (MO) dye, phenol, and bisphenol A. Results showed that excellent photocatalytic performance was obtained over Ag2S/Ag2CO3 composite photocatalysts with respect to Ag2S and Ag2CO3. With optimal content of Ag2S (32 wt%), the Ag2S-Ag2CO3 showed the highest photocatalytic degradation efficiency. Moreover, the structured property of Ag2S/Ag2CO3 greatly influenced the activity. Compared with Ag2S-Ag2CO3 and Ag2CO3@Ag2S, core-shell like Ag2S@Ag2CO3 demonstrated the highest activity and stability. The main reason for the boosting of photocatalytic performance was due to the formation of Ag2S/Ag2CO3 well contacted interface and unique electron structures. Ag2S/Ag2CO3 interface could significantly increase the separation efficiency of the photo-generated electrons (e(-)) and holes (h(+)), and production of OH radicals. More importantly, the low solubility of Ag2S shell could effectively protect the core of Ag2CO3, which further guarantees the stability of Ag2CO3.

  17. Anaemia and zidovudine-containing antiretroviral therapy in paediatric antiretroviral programmes in the IeDEA Paediatric West African Database to evaluate AIDS

    PubMed Central

    Renner, Lorna A; Dicko, Fatoumata; Kouéta, Fla; Malateste, Karen; Gueye, Ramatoulaye D; Aka, Edmond; Eboua, Tanoh K; Azondékon, Alain; Okomo, Uduok; Touré, Pety; Ekouévi, Didier; Leroy, Valeriane

    2013-01-01

    Introduction There is a risk of anaemia among HIV-infected children on antiretroviral therapy (ART) containing zidovudine (ZDV) recommended in first-line regimens in the WHO guidelines. We estimated the risk of severe anaemia after initiation of a ZDV-containing regimen in HIV-infected children included in the IeDEA West African database. Methods Standardized collection of data from HIV-infected children (positive PCR<18 months or positive serology ≥18 months) followed up in HIV programmes was included in the regional IeDEA West Africa collaboration. Ten clinical centres from seven countries contributed (Benin, Burkina Faso, Côte d'Ivoire, Gambia, Ghana, Mali and Senegal) to this collection. Inclusion criteria were age <16 years and starting ART. We explored the data quality of haemoglobin documentation over time and the incidence and predictors of severe anaemia (Hb<7g/dL) per 100 child-years of follow-up over the duration of first-line antiretroviral therapy. Results As of December 2009, among the 2933 children included in the collaboration, 45% were girls, median age was five years; median CD4 cell percentage was 13%; median weight-for-age z-score was −2.7; and 1772 (60.4%) had a first-line ZDV-containing regimen. At baseline, 70% of the children with a first-line ZDV-containing regimen had a haemoglobin measure available versus 76% in those not on ZDV (p≤0.01): the prevalence of severe anaemia was 3.0% (n=38) in the ZDV group versus 10.2% (n=89) in those without (p<0. 01). Over the first-line follow-up, 58.9% of the children had ≥1 measure of haemoglobin available in those exposed to ZDV versus 60.4% of those not (p=0.45). Severe anaemia occurred in 92 children with an incidence of 2.47 per 100 child-years of follow-up in those on a ZDV-containing regimen versus 4.25 in those not (p≤0.01). Adjusted for age at ART initiation and first-line regimen, a weight-for-age z-score ≤−3 was a strong predictor associated with a 5.59 times risk of severe

  18. High Visible Photoelectrochemical Activity of Ag Nanoparticle-Sandwiched CdS/Ag/ZnO Nanorods.

    PubMed

    Yang, Xu; Li, Hui; Zhang, Wu; Sun, Mingxuan; Li, Lequn; Xu, Ning; Wu, Jiada; Sun, Jian

    2017-01-11

    We report on the sensitizing of CdS-coated ZnO (CdS/ZnO) nanorods (NRs) by Ag nanoparticles (NPs) embedded between the CdS coating and the ZnO nanorod and the improved optical and photoelectrochemical properties of the Ag NP-sandwiched nanostructure CdS/Ag/ZnO NRs. The CdS/Ag/ZnO NRs were fabricated by growing Ag NPs on hydrothermally grown ZnO NRs and subsequently depositing CdS coatings followed by subsequent N2 annealing. The structure of the fabricated CdS/Ag/ZnO NRs was characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman backscattering, revealing that the ZnO NRs and the CdS coatings are both structured with hexagonal wurtzite and the Ag NPs contact well with ZnO and CdS. Optical properties were evaluated by measuring optical absorption and photoluminescence, showing that the Ag NPs behave well as sensitizers for optical property improvement and the CdS/Ag/ZnO NRs exhibit better photoresponse in a wide spectral region than CdS/ZnO because of plasmon-enhanced absorption due to the embedment of Ag NPs. The Ag NPs also serve as electron relays from CdS to ZnO, facilitating electron transfer from the CdS coatings to the ZnO NRs. The excellent photoresponse and efficient electron transfer make the CdS/Ag/ZnO NRs highly photoelectrochemically active. The CdS/Ag/ZnO NRs fabricated on indium-tin oxide present much better photoelectrochemical performance as photoanodes working in the visible region than CdS/ZnO NRs without Ag NPs. Under visible illumination, a maximum optical-to-chemical conversion efficiency of 3.13% is obtained for CdS/Ag/ZnO NR photoanodes against 1.35% for CdS/ZnO NR photoanodes.

  19. Electron and Phonon Dynamics in Hexagonal Pd Nanosheets and Ag/Pd/Ag Sandwich Nanoplates.

    PubMed

    Wang, Li; Sagaguchi, Takuya; Okuhata, Tomoki; Tsuboi, Motohiro; Tamai, Naoto

    2017-02-28

    Pd and its hybrid nanostructures have attracted considerable attention over the past decade, with both catalytic and plasmonic properties. The electron and phonon properties directly govern conversion efficiencies in applications such as energy collectors and photocatalysts. We report the dynamic processes of electron-phonon coupling and coherent acoustic phonon vibration in hexagonal Pd nanosheets and Ag/Pd/Ag sandwich nanoplates using transient absorption spectroscopy. The electron-phonon coupling constant of Pd nanosheets, GPd-nanosheet (8.7 × 10(17) W/(m(3)·K)) is larger than that of the bulk GPd (5.0 × 10(17) W/(m(3)·K)). The effective coupling constant Geff of Ag/Pd/Ag nanoplates decreases with increasing Ag shell thickness, finally approaching the bulk GAg. The variation of Geff is explained in terms of reduced density of states near Fermi level of Pd nanosheets with 1.8 nm ultrathin thickness. Coherent acoustic phonon vibration in Pd nanosheets is assigned to a fundamental breathing mode, similar to the vibration of benzene. The period increases with increasing Ag shell thickness. For Ag/Pd/Ag nanoplates with 20 nm thick Ag shells, the vibrational mode is ascribed to a quasi-extensional mode. The results show that the modes of the coherent acoustic phonon vibration transform with the geometric variation of Pd nanosheets and Ag/Pd/Ag nanoplates. Our results represent an understanding of quantum-confinement related electron dynamics and bulk-like phonon kinetics in the ultrathin Pd nanosheets and their hybrid nanostructures.

  20. An Ab Initio Study of the Low-Lying Doublet States of AgO and AgS

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

    1990-01-01

    Spectroscopic constants (D(sub o), r(sub e), mu(sub e), T(sub e)) are determined for the doublet states of AgO and AgS below approx. = 30000/cm. Large valence basis sets are employed in conjunction with relativistic effective core potentials (RECPs). Electron correlation is included using the modified coupled-pair functional (MCPF) and multireference configuration interaction (MRCI) methods. The A(sup 2)Sigma(sup +) - X(sup 2)Pi band system is found to occur in the near infrared (approx. = 9000/cm) and to be relatively weak with a radiative lifetime of 900 microns for A(sup 2)Sigma(sup +) (upsilon = 0). The weakly bound C(sup 2)Pi state (our notation), the upper state of the blue system, is found to require high levels of theoretical treatment to determine a quantitatively accurate potential. The red system is assigned as a transition from the C(sup 2)Pi state to the previously unobserved A(sup 2)Sigma(sup +) state. Several additional transitions are identified that should be detectable experimentally. A more limited study is performed for the vertical excitation spectrum of AgS. In addition, a detailed all-electron study of the X(sup 2)Pi and A(sup 2)Sigma(sup +) states of AgO is carried out using large atomic natural orbital (ANO) basis sets. Our best calculated D(sub o) value for AgO is significantly less than the experimental value, which suggests that there may be some systematic error in the experimental determination.

  1. Strongly visible-light responsive plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles for reduction of CO2 to methanol

    NASA Astrophysics Data System (ADS)

    An, Changhua; Wang, Jizhuang; Jiang, Wen; Zhang, Meiyu; Ming, Xijuan; Wang, Shutao; Zhang, Qinhui

    2012-08-01

    Plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles have been synthesized by a facile and versatile glycerol-mediated solution route. The as-prepared AgX:Ag nanoparticles exhibit regular shapes, i.e., cube-tetrapod-like AgCl:Ag nanoparticles and AgBr:Ag nanoplates. Compared with the pristine AgX, AgX:Ag nanocomposites display stronger absorption in the visible region due to the surface plasmon resonance of silver nanoparticles. The calculation of bandgaps and band positions indicates the as-achieved AgX:Ag nanoparticles can be used as a class of potential photocatalyst for the reduction of CO2. For example, reduction of CO2 under visible light irradiation with the assistance of the anisotropic AgX:Ag nanoparticles yields as much as 100 μmol methanol in the products. Furthermore, the AgX:Ag nanoparticles can maintain its structure and activity after 3 runs of reactions. Therefore, the present route opens an avenue to acquire plasmonic photocatalysts for conversion of CO2 into useful organic compounds.Plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles have been synthesized by a facile and versatile glycerol-mediated solution route. The as-prepared AgX:Ag nanoparticles exhibit regular shapes, i.e., cube-tetrapod-like AgCl:Ag nanoparticles and AgBr:Ag nanoplates. Compared with the pristine AgX, AgX:Ag nanocomposites display stronger absorption in the visible region due to the surface plasmon resonance of silver nanoparticles. The calculation of bandgaps and band positions indicates the as-achieved AgX:Ag nanoparticles can be used as a class of potential photocatalyst for the reduction of CO2. For example, reduction of CO2 under visible light irradiation with the assistance of the anisotropic AgX:Ag nanoparticles yields as much as 100 μmol methanol in the products. Furthermore, the AgX:Ag nanoparticles can maintain its structure and activity after 3 runs of reactions. Therefore, the present route opens an avenue to acquire plasmonic photocatalysts for conversion of CO2

  2. Calibration of qualitative HBsAg assay results for quantitative HBsAg monitoring.

    PubMed

    Gunning, Hans; Adachi, Dena; Tang, Julian W

    2014-10-01

    Evidence is accumulating that quantitative hepatitis B surface antigen monitoring may be useful in managing patients with chronic HBV infection on certain treatment regimens. Based on these results with the Abbott Architect qualitative and quantitative HBsAg assays, it seems feasible to convert qualitative to quantitative HBsAg values for this purpose.

  3. Ultra-Fast Synthesis for Ag2Se and CuAgSe Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    DUAN, H. Z.; LI, Y. L.; ZHAO, K. P.; QIU, P. F.; SHI, X.; CHEN, L. D.

    2016-10-01

    Ag2Se and CuAgSe have been recently reported as promising thermoelectric materials at room temperature. The traditional melting-annealing-sintering processes are used to grow Ag2Se and CuAgSe materials with the disadvantages of high costs of energy and time. In this work, phase-pure polycrystalline Ag2Se and CuAgSe compounds were synthesized from raw elemental powders directly by manual mixing followed by spark plasma sintering (MM-SPS) in a few minutes. The influence of SPS heating rate on the phase composition, microstructure, and thermoelectric properties, including Seebeck coefficient, electrical conductivity, and thermal conductivity, were investigated. The zTs of 0.8 at 390 K and 0.6 at 450 K are obtained for Ag2Se and CuAgSe, respectively, which is comparable with the values in the materials prepared by the traditional method. Furthermore, this ultrafast sample synthesis can significantly save material synthesis time and thus has the obvious advantage for large-scale production.

  4. Facile synthesis of sunlight-driven AgCI:Ag plasmonic nanophotocatalyst.

    SciTech Connect

    An, C.; Peng, S.; Sun, Y.; Center for Nanoscale Materials; Univ. of Illinois

    2010-06-18

    Highly efficient plasmonic photocatalysts of AgCl:Ag hybrid nanoparticles are successfully synthesized via a one-pot synthetic approach involving a precipitation reaction followed by polyol reduction. The as-synthesized nanoparticles exhibit high catalytic performance under visible light and sunlight for decomposing organics, such as methylene blue.

  5. Beet Juice-Induced Green Fabrication of Plasmonic AgCl/Ag Nanoparticles

    EPA Science Inventory

    A simple, green, and fast approach (complete within 5 min) was explored for the fabrication of hybrid AgCl/Ag plasmonic nanoparticles under microwave (MW) irradiation. In this method, beet juice served as a reducing reagent, which is an abundant sugar-rich agricultural produce. I...

  6. Ag on Si(111) from basic science to application

    SciTech Connect

    Belianinov, Aleksey

    2012-01-01

    In our work we revisit Ag and Au adsorbates on Si(111)-7x7, as well as experiment with a ternary system of Pentacene, Ag and Si(111). Of particular interest to us is the Si(111)-(√3x√3)R30°}–Ag (Ag-Si-√3 hereafter). In this thesis I systematically explore effects of Ag deposition on the Ag-Si-√3 at different temperatures, film thicknesses and deposition fluxes. The generated insight of the Ag system on the Si(111) is then applied to generate novel methods of nanostructuring and nanowire growth. I then extend our expertise to the Au system on the Ag-Si(111) to gain insight into Au-Si eutectic silicide formation. Finally we explore behavior and growth modes of an organic molecule on the Ag-Si interface.

  7. Morphology and mechanical properties of nanocrystalline Cu/Ag alloy

    NASA Astrophysics Data System (ADS)

    Li, Ao; Szlufarska, Izabela

    2017-04-01

    Hybrid Monte Carlo (MC)/molecular dynamics (MD) simulations are conducted to study the microstructures of nanocrystalline (nc) Cu/Ag alloys with various Ag concentrations. When the Ag concentration is below 50 Ag atoms/nm!, an increase in Ag concentration leads to a gradual growth of monolayer grain boundary (GB) complexions into nanolayer complexions. Above the concentration of 50 Ag atoms/nm!, wetting layers with a bulk crystalline phase are observed. The effects of Ag on mechanical properties and deformation mechanisms of nc Cu/Ag alloys are investigated in MD simulations of uniaxial tension. GB sliding resistance is found to first increase and then decrease with an increase in Ag concentration. Surprisingly, we also find that the dislocation density decreases monotonically with an increase in Ag concentration, which suggests that the grain interiors are softened by the introduction of Ag dopants at GBs. In addition, there is a critical Ag concentration that maximizes flow stress of nc Cu/Ag alloys. The flow stress, GB sliding resistance, and the intragranular dislocation densities become less sensitive to Ag dopants when the grain diameter increases from 5nm to 40nm.

  8. Exploring Northwest China's agricultural water-saving strategy: analysis of water use efficiency based on an SE-DEA model conducted in Xi'an, Shaanxi Province.

    PubMed

    Mu, L; Fang, L; Wang, H; Chen, L; Yang, Y; Qu, X J; Wang, C Y; Yuan, Y; Wang, S B; Wang, Y N

    Worldwide, water scarcity threatens delivery of water to urban centers. Increasing water use efficiency (WUE) is often recommended to reduce water demand, especially in water-scarce areas. In this paper, agricultural water use efficiency (AWUE) is examined using the super-efficient data envelopment analysis (DEA) approach in Xi'an in Northwest China at a temporal and spatial level. The grey systems analysis technique was then adopted to identify the factors that influenced the efficiency differentials under the shortage of water resources. From the perspective of temporal scales, the AWUE increased year by year during 2004-2012, and the highest (2.05) was obtained in 2009. Additionally, the AWUE was the best in the urban area at the spatial scale. Moreover, the key influencing factors of the AWUE are the financial situations and agricultural water-saving technology. Finally, we identified several knowledge gaps and proposed water-saving strategies for increasing AWUE and reducing its water demand by: (1) improving irrigation practices (timing and amounts) based on compatible water-saving techniques; (2) maximizing regional WUE by managing water resources and allocation at regional scales as well as enhancing coordination among Chinese water governance institutes.

  9. Solid phase extraction of lead, cadmium and zinc on biodegradable polyhydroxybutyrate diethanol amine (PHB-DEA) polymer and their determination in water and food samples.

    PubMed

    Tuzen, Mustafa; Sahiner, Samet; Hazer, Baki

    2016-11-01

    A new biodegradable polyhydroxybutyrate diethanol amine (PHB-DEA) polymer was used as adsorbent for the sensitive and selective separation, preconcentration and determination of Pb(II), Cd(II) and Zn(II) by using atomic absorption spectrometry. Diethyl dithiocarbamate was used as chelating reagent. Analytical parameters such as pH, eluent type and its volume, flow rates of sample solution, ligand amount, sample volume were optimized. Effects of some cations, anions and transition metal ions were also investigated. Enrichment factor and relative standard deviation were found to be 100 and 3%, respectively. The limits of detection based on three times standard deviation of blanks (N=21) were found 1.05μgL(-1) for Pb(II), 0.42μgL(-1) for Cd(II) and 0.13μgL(-1) for Zn(II). Limits of quantification (10s, N=21) were found 3.47μgL(-1) for Pb(II), 1.39μgL(-1) for Cd(II) and 0.43μgL(-1) for Zn(II). Accuracy evaluation of the method was confirmed with analyses of certified reference materials (NIST SRM 1515 Apple leaves, IAEA 336 Lichen, GBW 07605 Tea). Optimized method was applied to tap water and food samples after microwave digestion method. Cadmium and lead values in some samples were found higher than legal limits.

  10. Oligo(FcDC-co-CholDEA) with ferrocene in the main chain and cholesterol as a pendant group-preparation and unusual properties.

    PubMed

    Yan, Junlin; Liu, Jing; Sun, Yuanhui; Jing, Ping; He, Panli; Gao, Di; Fang, Yu

    2010-10-21

    With ever-increasing need for thin, flexible, and functional materials in electrochemical systems, various techniques have been explored for creating materials used in fuel cells, batteries, electrochromic devices, solar cells, and sensors. In the present study, a novel ferrocene (Fc) and cholesterol (Chol)-containing oligomer, oligo(FcDC-co-CholDEA), was specially designed and prepared by putting Fc in the main chain and Chol as a side group. MALDI-TOF MS and freezing point depression measurements revealed that in average each oligomer contains three Fc units and three Chol units. Cyclic voltammetric measurements revealed that the oligomer displays superior electrochemical stability if compared with other Fc derivatives containing only one Fc unit and one or two Chol unit and with poly(ferrocenylsilane) with Fc in the main chain. In particular, the Fc-containing oligomer possesses an unusual oxidation center, of which the oxidation potential could be as high as 1.81 V. The oligomer is also superior in self-assembly, as demonstrated by forming an LB film of layered structures. Furthermore, supramolecular films with high mechanical strength in the wet state can be prepared by employing a simple solution casting method. This finding demonstrates that self-assembly is a simple but effective way to create films of potential uses in real-life applications provided proper building blocks are designed and employed.

  11. Observation of nonvolatile resistive memory switching characteristics in Ag/graphene-oxide/Ag devices.

    PubMed

    Venugopal, Gunasekaran; Kim, Sang-Jae

    2012-11-01

    In this paper, we report highly stable and bipolar resistive switching effects of Ag/Graphene oxide thinfilm/Ag devices. The graphene-oxide (GO) thinfilms were prepared on Ag/SiO2/Si substrates by spin-coating technique. The Ag/GO/Ag devices showed a steady and bipolar resistive switching characteristic. The resistance switching from low resistance state (LRS) and high resistance state (HRS) with the resistance ratio of HRS to LRS of about 10 which was attained at a voltage bias of 0.1 V. Based on the filamentary conduction model, the dominant conduction mechanism of switching effect was well explained. Our results show GO can be a promising candidate for future development of nonvolatile memory devices.

  12. Noble-metal Ag nanoparticle chains: annealing Ag/Bi superlattice nanowires in vacuum

    NASA Astrophysics Data System (ADS)

    Xu, Shao Hui; Fei, Guang Tao; You, Qiao; Gao, Xu Dong; Huo, Peng Cheng; De Zhang, Li

    2016-09-01

    One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10-5 Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains.

  13. Noble-metal Ag nanoparticle chains: annealing Ag/Bi superlattice nanowires in vacuum.

    PubMed

    Xu, Shao Hui; Fei, Guang Tao; You, Qiao; Gao, Xu Dong; Huo, Peng Cheng; De Zhang, Li

    2016-09-16

    One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10(-5) Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains.

  14. Facile synthesis of AgCl/polydopamine/Ag nanoparticles with in-situ laser improving Raman scattering effect

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Zhang, Wenqi; Wang, Lin; Wang, Feng; Yang, Haifeng

    2017-01-01

    We reported a simple and fast method to prepare a composite material of polydopamine (PDA) adlayer covered cubic AgCl core, which was inlaid with Ag nanoparticles (NPs), shortly named as AgCl/PDA/AgNPs. The resultant AgCl/PDA/AgNPs could be employed as surface-enhanced Raman scattering (SERS) substrate for in-situ detection and the SERS activity could be further greatly improved due to the production of more AgNPs upon laser irradiation. With 4-mercaptopyridine (4-Mpy) as the probe molecule, the enhancement factor could reach 107. Additionally, such SERS substrate shows good reproducibility with relative standard deviation of 7.32% and long term stability (after storage for 100 days under ambient condition, SERS intensity decay is less than 25%). In-situ elevating SERS activity of AgCl/PDA/AgNPs induced by laser may be beneficial to sensitive analysis in practical fields.

  15. Spin coating of Ag nanoparticles: Effect of reduction

    SciTech Connect

    Ansari, A. A. Sartale, S. D.

    2014-04-24

    A surfactant free method for the growth of Ag nanoparticles on glass substrate by spin coating of Ag ions solution followed by chemical reduction in aqueous hydrazine hydrate (HyH) solution has been presented. Appearance of surface plasmon resonance confirms the formation of Ag nanoparticles. Morphology and absorbance spectra of Ag nanoparticles films are used to examine effect of hydrazine concentration on the growth of Ag nanoparticles. SEM images show uniformly distributed Ag nanoparticles. Rate constant was found to be dependent on HyH concentration as a consequence influence particle size.

  16. Synthesis, characterization and antimycobacterial activity of Ag(I)-aspartame, Ag(I)-saccharin and Ag(I)-cyclamate complexes.

    PubMed

    Cavicchioli, Maurício; Leite, Clarice Q F; Sato, Daisy N; Massabni, Antonio C

    2007-10-01

    The present work describes the synthesis and antimycobacterial activity of three Ag(I)-complexes with the sweeteners aspartame, saccharin, and cyclamate as ligands, with the aim of finding new candidate substances for fighting tuberculosis and other mycobacterial infections. The minimal inhibitory concentration of these three complexes was investigated in order to determine their in-vitro antimycobacterial activity against Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium malmoense, and Mycobacterium kansasii. The MIC values were determined using the Microplate Alamar Blue Assay. The best MIC values found for the complexes were 9.75 microM for Ag(I)-aspartame against M. kansasii and 15.7 microM for Ag(I)-cyclamate against M. tuberculosis.

  17. Template synthesis of Ag/AgCl microrods and their efficient visible light-driven photocatalytic performance

    SciTech Connect

    Chen, Hua; Xiao, Liang; Huang, Jianhua

    2014-09-15

    Highlights: • Preparation ofAg/AgCl microrods by reaction of Ag{sub 2}WO{sub 4} microrods with NaCl solution. • Generation of metallic Ag is induced by the ambient light in the synthesis process. • Ag/AgCl shows excellent visible light-driven photodegradation of organic dyes. - Abstract: Ag/AgCl microrods, aggregated by nanoparticles with a diameter ranging from 100 nm to 2 μm, were prepared by an ion-exchange reaction at 80 °C between Ag{sub 2}WO{sub 4} template and NaCl solution. The existence of metallic Ag species was confirmed by XRD, DRS and XPS measurements. Ag/AgCl microrods showed excellent photocatalytic activity for the degradation of rhodamine B and methylene blue under visible light irradiation. The degradation rate constants of rhodamine B and methylene blue are 0.176 and 0.114 min{sup −1}, respectively. The cycling photodegradation experiments suggest that Ag/AgCl microds could be employed as stable plasmonic photocatalysts for the degradation of organic dyes under visible light irradiation.

  18. BiPO4 photocatalyst employing synergistic action of Ag/Ag3PO4 nanostructure and graphene nanosheets

    NASA Astrophysics Data System (ADS)

    Mohaghegh, N.; Rahimi, E.

    2016-06-01

    Graphene-supported BiPO4/Ag/Ag3PO4 photocatalyst has been fabricated by simple hydrothermal and impregnation reaction. In BiPO4/Ag/Ag3PO4 based on Reduced Graphene Oxide (RGO), this network renders numerous pathways for rapid mass transport, strong adsorption and multireflection of incident light; meanwhile, the interface between BiPO4/Ag/Ag3PO4 and RGO increases the active sites and electron transfer rate. BiPO4/Ag/Ag3PO4 based on RGO noticeably exhibited high photocatalytic activity than that of BiPO4/Ag/Ag3PO4 and P25 under visible light irradiation for cationic dye (Rhodamine B), anionic dye (methyl orange) and 4-chlorophenol (4-CP) as a neutral pollutant, which are usually difficult to be degraded over the other catalysts. This enhanced photocatalytic activity of Graphene-supported BiPO4/Ag/Ag3PO4 for all pollutants could be mainly ascribed to the reinforced charge transfer from BiPO4/Ag/Ag3PO4 to RGO, which suppresses the recombination of electron/hole pairs. Besides that, this photocatalyst can be used repetitively with a high photocatalytic activity and no apparent loss of activity occurs. The results reveal that the RGO nanosheets work as a photocatalyst promoter during the photocatalytic reaction, leading to an improved photocatalytic activity.

  19. Preparation of Ag2O/Ag2CO3/MWNTs composite photocatalysts for enhancement of ciprofloxacin degradation

    NASA Astrophysics Data System (ADS)

    Wang, Huiqin; Li, Jinze; Huo, Pengwei; Yan, Yongsheng; Guan, Qingfeng

    2016-03-01

    The Ag2O/Ag2CO3/multi-walled carbon nanotube (MWNTs) composite photocatalysts were prepared by calcination of the obtained precipitate. The structures and morphology of as-prepared composite photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS). The Ag2O/Ag2CO3/MWNTs composite photocatalysts exhibit higher degradation rate of ciprofloxacin (CIP) than the pure Ag2CO3, Ag2O/Ag2CO3 and Ag2CO3/MWNTs under visible light irradiation. The amount of loaded Ag2CO3 onto MWNTs and calcined time for Ag2CO3/MWNTs were systematically investigated, and the optimal amount of loaded Ag2CO3 and calcined time of Ag2CO3/MWNTs are 150 wt% and 10 min, respectively. The highest photocatalytic degradation rate of CIP could reach 76% under optimal conditions. The active species trapping experiments were also analyzed, the results show that the holes are main contributor for the degradation processes of CIP, furthermore the electrons, rad O2- and rad OH are also crucially influenced the photocatalytic degradation processes of CIP. The possible photocatalytic processes of CIP with Ag2O/Ag2CO3/MWNTs composite photocatalyst are also proposed.

  20. Mussel-inspired green synthesis of polydopamine-Ag-AgCl composites with efficient visible-light-driven photocatalytic activity.

    PubMed

    Cai, Aijun; Wang, Xiuping; Guo, Aiying; Chang, Yongfang

    2016-09-01

    Polydopamine-Ag-AgCl composites (PDA-Ag-AgCl) were synthesized using a mussel-inspired method at room temperature, where PDA acts as a reducing agent to obtain the noble Ag nanoparticles from a precursor. The morphologies and structures of the as-prepared PDA-Ag-AgCl were characterized by several techniques including field emission scanning electron microscopy (FESEM), transmission electron microscopy (SEM), Raman spectra, and X-Ray photoelectron spectrum (XPS). The morphological observation depicts formation of nanoparticles with various micrometer size diameters and surface XPS analysis shows presence of various elements including Ag, N, Cl, and O. The enhanced absorbance of the PDA-Ag-AgCl particles in the visible light region is confirmed through UV-Vis diffuse reflectance spectra (DRS), and the charge transfer is demonstrated by photoluminescence (PL) and photocurrent response. The synthesized PDA-Ag-AgCl composites could be used as visible-light-driven photocatalysts for the degradation of Rhodamine B. The elevated photocatalytic activity is ascribed to the effective charge transfer from plasmon-excited Ag to AgCl that can improve the efficiency of the charge separation during the photocatalytic reaction. Furthermore, differences in the photocatalytic performance among the different PDA-Ag-AgCl composites are noticed that could be attributed to the Brunauer-Emmett-Teller (BET) specific surface area, which benefits to capture the visible light efficiently. The PDA-Ag-AgCl exhibits excellent stability without a significant loss in activity after 5cycles. The proposed method is low-cost and environmentally friendly, hence a promising new way to fabricate plasmon photocatalysts.

  1. Effect of cysteine and humic acids on bioavailability of Ag from Ag nanoparticles to a freshwater snail

    USGS Publications Warehouse

    Luoma, Samuel N.; Tasha Stoiber,; Croteau, Marie-Noele; Isabelle Romer,; Ruth Merrifeild,; Lead, Jamie

    2016-01-01

    Metal-based engineered nanoparticles (NPs) will undergo transformations that will affect their bioavailability, toxicity and ecological risk when released to the environment, including interactions with dissolved organic material. The purpose of this paper is to determine how interactions with two different types of organic material affect the bioavailability of silver nanoparticles (AgNPs). Silver uptake rates by the pond snail Lymnaea stagnalis were determined after exposure to 25 nmol l-1 of Ag as PVP AgNPs, PEG AgNPs or AgNO3, in the presence of either Suwannee River humic acid or cysteine, a high-affinity thiol-rich organic ligand. Total uptake rate of Ag from the two NPs was either increased or not strongly affected in the presence of 1 – 10 mg 1-1 humic acid. Humic substances contain relatively few strong ligands for Ag explaining their limited effects on Ag uptake rate. In contrast, Ag uptake rate was substantially reduced by cysteine. Three components of uptake from the AgNPs were quantified in the presence of cysteine using a biodynamic modeling approach: uptake of dissolved Ag released by the AgNPs, uptake of a polymer or large (>3kD) Ag-cysteine complex and uptake of the nanoparticle itself. Addition of 1:1 Ag:cysteine reduced concentrations of dissolved Ag, which contributed to, but did not fully explain the reductions in uptake. A bioavailable Ag-cysteine complex (> 3kD) appeared to be the dominant avenue of uptake from both PVP AgNPs and PEG AgNPs in the presence of cysteine. Quantifying the different avenues of uptake sets the stage for studies to assess toxicity unique to NPs.

  2. One-pot synthesis of ternary Ag₂CO₃/Ag/AgCl photocatalyst in natural geothermal water with enhanced photocatalytic activity under visible light irradiation.

    PubMed

    Yao, Xiaxi; Liu, Xiaoheng

    2014-09-15

    Geothermal water is a clean, cheap and renewable resource and it is widely distributed all over the world. In this work, ternary Ag2CO3/Ag/AgCl photocatalyst has been successfully synthesized via a one-pot precipitation method in natural geothermal water at room temperature, wherein the geothermal water serves as the source of chlorine and carbonate. The results suggest that the Ag/AgCl nanoparticles are anchored on the surface of Ag2CO3 and Ag2CO3/Ag/AgCl composite shows strong absorption ability in the visible light region. The evaluation of the photocatalytic activity indicates that the as-synthesized Ag2CO3/Ag/AgCl photocatalyst exhibits higher photocatalytic performance for the degradation of methylene blue (MB) aqueous solution under visible light irradiation than one-component (Ag2CO3), two-component (Ag/AgCl, Ag2CO3/AgCl) and the mechanical mixture of Ag2CO3 and Ag/AgCl. The trapping experiments confirmed that holes (h(+)) and (•)O2(-) were the two main active species in the photocatalytic process. Finally, a possible Z-scheme photocatalytic mechanism of the charge transfer was proposed for the enhanced photocatalytic performance. This work may open up new insights into the application of cheap geothermal water resources in the word and provide new opportunities for facile fabrication of Ag/AgCl-based photocatalysts.

  3. Ag/ZnO heterostructure nanocrystals: synthesis, characterization, and photocatalysis.

    PubMed

    Zheng, Yuanhui; Zheng, Lirong; Zhan, Yingying; Lin, Xingyi; Zheng, Qi; Wei, Kemei

    2007-08-20

    A high yield of the dimer-type heterostructure of Ag/ZnO nanocrystals with different Ag contents is successfully prepared through a simple solvothermal method in the absence of surfactants. The samples are characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and IR spectroscopy. The results show that all samples are composed of metallic Ag and ZnO; Ag nanoparticles locate on the surface of ZnO nanorods; the binding energy of Ag 3d(5/2) for the Ag/ZnO sample with a Ag content of 5.0 atom % shifts remarkably to the lower binding energy compared with the corresponding value of pure metallic Ag because of the interaction between Ag and ZnO nanocrystals; the concentration of oxygen vacancy for the as-synthesized samples varies with the increasing Ag content, and the Ag/ZnO sample with a Ag content of 5.0 atom % has the largest density of oxygen vacancy. In addition, the relationship between their structure and photocatalytic property is investigated in detail. It is found that the photocatalytic property is closely related to its structure, such as heterostructure, oxygen defect, and crystallinity. The presence of metallic Ag nanoparticles and oxygen vacancy on the surface of ZnO nanorods promotes the separation of photogenerated electron-hole pairs and thus enhances the photocatalytic activity.

  4. 3D [Ag-Mg] polyanionic frameworks in the La 4Ag 10Mg 3 and La 4Ag 10.3Mg 12 new ternary compounds

    NASA Astrophysics Data System (ADS)

    Solokha, Pavlo; De Negri, Serena; Pavlyuk, Volodymyr; Eck, Bernhard; Dronskowski, Richard; Saccone, Adriana

    2010-12-01

    The crystal structures of two new ternary phases, La 4Ag 10Mg 3 and La 4Ag 10.3Mg 12, were refined from X-ray single crystal diffraction data. La 4Ag 10Mg 3 crystallizes in the Ca 4Au 10In 3 structure type, an ordered variant of the binary Zr 7Ni 10 compound: orthorhombic, Cmce, oS68, a=14.173(5), b=10.266(3), c=10.354(3) Å, Z=4, w R2=0.0826, 676 F2 values, 50 variables. La 4Ag 10.3Mg 12 represents a new structure type: orthorhombic, Cmmm, oS116-10.32, a=9.6130(3), b=24.9663(8), c=9.6333(2) Å, Z=4, w R2=0.0403, 1185 F2 values, 101 variables. The structural analysis of both compounds, highlighting a significant contraction of the Ag-Mg distances, suggests the existence of three-dimensional [Ag-Mg] networks hosting La atoms. LMTO calculations applied to La 4Ag 10Mg 3 indicate that the strongest bonds occur for Ag-Ag and Ag-Mg interactions, and confirm the presence of a 3D ∞[Ag 10Mg 3] δ- polyanionic framework balanced by positively charged La atoms.

  5. Bipolar Ag-Zn battery

    NASA Technical Reports Server (NTRS)

    Giltner, L. John

    1994-01-01

    The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected

  6. Bipolar Ag-Zn battery

    NASA Astrophysics Data System (ADS)

    Giltner, L. John

    1994-02-01

    The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected

  7. Spectrophotometry of the shell around AG Carinae

    NASA Technical Reports Server (NTRS)

    Mitra, P. Mila; Dufour, Reginald J.

    1990-01-01

    Spatially-resolved long-slit spectrophotometry are presented for two regions of the shell nebula around the P-Cygni variable star AG Carinae. The spectra cover the 3700-6800 A wavelength range. Emission-line diagnostics are used to derive extinction, electron temperatures, and densities for various positions in the nebula. The chemical abundances and ionization structure are calculated and compared with other types of planetary nebulae and shells around other luminous stars. It is found that the N/O and N/S ratios of Ag Car are high compared to solar neighborhood ISM values. The O/H depletion found for the AG Car shell approaches that found in the condensations of the Eta Car system.

  8. Enhanced chemiluminescence of the luminol-AgNO3 system by Ag nanoparticles.

    PubMed

    Li, Shifeng; Sun, Huimin; Wang, Dong; Hong, Jianguo; Tao, Shanjun; Yu, Haiyin; Wang, Xiuhua; Wei, Xianwen

    2012-01-01

    The oxidation reaction of luminol with AgNO(3) can produce chemiluminescence (CL) in the presence of silver nanoparticles (NPs) in alkaline solution. Based on the studies of UV-vis absorption spectra, photoluminescence (PL) spectra and CL spectra, a CL enhancement mechanism is proposed. The CL emission spectrum of the luminol-AgNO(3)-Ag NPs system indicated that the luminophore was still 3-aminophthalate. On injection of silver nanoparticles into the mixture of luminol and AgNO(3), they catalysed the reduction of AgNO(3) by luminol. The product luminol radicals reacted with the dissolved oxygen, to produce a strong CL emission. As a result, the CL intensity was substantially increased. Moreover, the influences of 18 amino acids, e.g. cystine, tyrosine and asparagine, and 25 organic compounds, including gallic acid, tannic acid and hydroquinone, on the luminol-AgNO(3)-Ag NPs CL system were studied by a flow-injection procedure, which led to an effective method for detecting these compounds.

  9. Ag/FeCo/Ag core/shell/shell magnetic nanoparticles with plasmonic imaging capability.

    PubMed

    Takahashi, Mari; Mohan, Priyank; Nakade, Akiko; Higashimine, Koichi; Mott, Derrick; Hamada, Tsutomu; Matsumura, Kazuaki; Taguchi, Tomohiko; Maenosono, Shinya

    2015-02-24

    Magnetic nanoparticles (NPs) have been used to separate various species such as bacteria, cells, and proteins. In this study, we synthesized Ag/FeCo/Ag core/shell/shell NPs designed for magnetic separation of subcellular components like intracellular vesicles. A benefit of these NPs is that their silver metal content allows plasmon scattering to be used as a tool to observe detection by the NPs easily and semipermanently. Therefore, these NPs are considered a potential alternative to existing fluorescent probes like dye molecules and colloidal quantum dots. In addition, the Ag core inside the NPs suppresses the oxidation of FeCo because of electron transfer from the Ag core to the FeCo shell, even though FeCo is typically susceptible to oxidation. The surfaces of the Ag/FeCo/Ag NPs were functionalized with ε-poly-L-lysine-based hydrophilic polymers to make them water-soluble and biocompatible. The imaging capability of the polymer-functionalized NPs induced by plasmon scattering from the Ag core was investigated. The response of the NPs to a magnetic field using liposomes as platforms and applying a magnetic field during observation by confocal laser scanning microscopy was assessed. The results of the magnetophoresis experiments of liposomes allowed us to calculate the magnetic force to which each liposome was subjected.

  10. The axisymmetric stellar wind of AG Carinae

    NASA Technical Reports Server (NTRS)

    Schulte-Ladbeck, Regina E.; Clayton, Geoffrey C.; Hillier, D. John; Harries, Tim J.; Howarth, Ian D.

    1994-01-01

    We present optical linear spectropolarimetry of the Luminous Blue Variable AG Carinae obtained after a recent visual brightness increase. The absence of He II lambda 4686 emission, together with the weakening of the He I spectrum and the appearance of Fe lines in the region around 5300 A, confirm that AG Car has started a new excursion across the HR diagram. The H alpha line profile exhibits very extended line wings that are polarized differently in both amount and position angle from either the continuum or the line core. The polarization changes across H alpha, together with variable continuum polarization, indicate the presence of intrinsic polarization. Coexistence of the line-wing polarization with extended flux-line wings evidences that both are formed by electron scattering in a dense wind. The position angle rotates across the line profiles, in a way that presently available models suggest is due to rotation and expansion of the scattering material. AG Car displays very large variations of its linear polarization with time, Delta P approximately 1.2%, indicating significant variations in envelope opacity. We find that the polarization varies along a preferred position angle of approximately 145 deg (with a scatter of +/- 10 deg) which we interpret as a symmetry axis of the stellar wind (with an ambiguity of 90 deg). This position angle is co-aligned with the major axis of the AG Car ring nebula and perpendicular to the AG Car jet. Our observations thus suggest that the axisymmetric geometry seen in the resolved circumstellar environment at various distances already exists within a few stellar radii of AG Car. From the H alpha polarization profile we deduce an interstellar polarization of Q = 0.31%, U = -1.15% at H alpha. The inferred interstellar polarization implies that the intrinsic polarization is not always of the same sign. This indicates either significant temporal changes in the envelope geometry, or it may arise from effects of multiple scattering

  11. Siberian Snake solenoid for the AGS

    SciTech Connect

    Ratner, L. G.

    1991-01-01

    Recent experiments at the Indiana University Cyclotron Facility (IUCF) have demonstrated that Siberian Snakes'' can be used to preserve the polarization of an accelerated polarized beam in a circular accelerator. Retrofitting full snakes into accelerators such as the Alternating Gradient Synchrotron (AGS) at Brookhaven is almost impossible due to space limitations, but a partial snake that can correct depolarization due to imperfection resonances with 1/20 to 1/30 of a full strength snake seems to present a viable option. We describe such a device for the AGS and give the design criteria in terms of simplicity of accelerator operation and level of achievable polarization. 2 refs., 5 figs., 1 tab.

  12. Facile synthesis of novel Ag/AgI/BiOI composites with highly enhanced visible light photocatalytic performances

    SciTech Connect

    Cao, Jing; Zhao, Yijie; Lin, Haili; Xu, Benyan; Chen, Shifu

    2013-10-15

    Novel Ag/AgI/BiOI composites were controllably synthesized via a facile ion-exchange followed by photoreduction strategy by using hierarchical BiOI microflower as substrate. The as-prepared Ag/AgI/BiOI composites were studied by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area analyzer and UV–vis diffuse reflectance spectroscopy (DRS). Under visible light (λ>420 nm), Ag/AgI/BiOI displayed highly enhanced photocatalytic activities for degradation of methyl orange (MO) compared to the pure hierarchical BiOI, which was mainly ascribed to the highly efficient separation of electrons and holes through the closely contacted interfaces in the Ag/AgI/BiOI ternary system. - Graphical abstract: Ag/AgI/BiOI displayed excellent photocatalytic activities for methyl orange degradation under visible light, which was mainly ascribed to the highly efficient separation of electrons and holes through Z-scheme pathway. Display Omitted - Highlights: • Novel Ag/AgI/BiOI composites were successfully synthesized. • Ag/AgI/BiOI displayed higher visible light activities than those of pure BiOI and AgI. • ·O{sub 2}{sup −} and h{sup +}, especially ·O{sub 2}{sup −}, dominated the photodegradation process of MO. • A Z-scheme pattern was adopted for Ag/AgI/BiOI activity enhancement.

  13. Ag@AgHPW as a plasmonic catalyst for visible-light photocatalytic degradation of environmentally harmful organic pollutants

    SciTech Connect

    Zhou, Wenhui; Cao, Minhua Li, Na; Su, Shuangyue; Zhao, Xinyu; Wang, Jiangqiang; Li, Xianghua; Hu, Changwen

    2013-06-01

    Graphical abstract: Ag@Ag{sub x}H{sub 3−x}PW12O40 (Ag@AgHPW) nanoparticles (NPs), a new visible-light driven plasmonic photocatalyst, are prepared by a green photoreduction strategy without the addition of any surfactant, which show a high activity and stability for the degradation of methyl blue (MB) under visible light irradiation. - Highlights: • A new visible-light driven photocatalyst Ag@Ag{sub x}H{sub 3−x}PW{sub 12}O{sub 40} was designed. • The photocatalyst shows a high activity for the degradation of methyl blue. • The high activity can be ascribed to the synergy of photoexcited AgHPW and Ag. - Abstract: Ag@Ag{sub x}H{sub 3−x}PW{sub 12}O{sub 40} (Ag@AgHPW) nanoparticles (NPs), a new visible-light driven plasmonic photocatalyst, are prepared by a green photoreduction strategy without the addition of any surfactant. They show strong absorption in the visible region because of the localized surface plasmon resonance (LSPR) of Ag NPs. This plasmonic photocatalyst shows a high activity and stability for the degradation of methyl blue (MB) under visible light irradiation, which could be attributed to the highly synergy of photoexcited Ag{sub x}H{sub 3−x}PW{sub 12}O{sub 40} (AgHPW) and plasmon-excited Ag NPs and the confinement effects at interfaces between polyoxometalates (POMs) and silver. POM anions have redox ability and high photocatalytic activity, whereas Ag NPs could effectively accelerate the separation of electrons and holes, both of which contribute to their high activity.

  14. Ag Nanowire Based Transparent Conductor for CIGS PV

    SciTech Connect

    Woods, L. M.; Wolk, J.; Smith, M.; Davande, H.; Ribelin, R. M.; Perkins, C. L.

    2011-01-01

    Coated silver nanowires (AgNW) have been considered as a replacement for transparent conducting oxides (TCOs) in CIGS based photovoltaic devices. The advantages of AgNW over TCOs are discussed, and optical and electrical characteristics of AgNWs on glass are presented. Similarly fabricated AgNWs with varying sheet resistance on CIGS devices were tested against ITO transparent conductor controls. The CIGS was produced using a roll-to-roll technique on a flexible polymer substrate. Variations in the ZnO layer resistivity that are adjacent to the AgNW layer in the CIGS device were also tested. Device results indicate similar Jsc, but a reduced FF for cells made with the AgNWs, and Voc dependence on the resistivity of the coated AgNW and ZnO window layers. FF and Voc losses associated with the use of AgNWs are discussed.

  15. Hierarchical Ag mesostructures for single particle SERS substrate

    NASA Astrophysics Data System (ADS)

    Xu, Minwei; Zhang, Yin

    2017-01-01

    Hierarchical Ag mesostructures with highly rough surface morphology have been synthesized at room temperature through a simple seed-mediated approach. Electron microscopy characterizations indicate that the obtained Ag mesostructures exhibit a textured surface morphology with the flower-like architecture. Moreover, the particle size can be tailored easily in the range of 250-500 nm. For the growth process of the hierarchical Ag mesostructures, it is believed that the self-assembly mechanism is more reasonable rather than the epitaxial overgrowth of Ag seed. The oriented attachment of nanoparticles is revealed during the formation of Ag mesostructures. Single particle surface enhanced Raman spectra (sp-SERS) of crystal violet adsorbed on the hierarchical Ag mesostructures were measured. Results reveal that the hierarchical Ag mesostructures can be highly sensitive sp-SERS substrates with good reproducibility. The average enhancement factors for individual Ag mesostructures are estimated to be about 106.

  16. Low implementation of Xpert MTB/RIF among HIV/TB co-infected adults in the International epidemiologic Databases to Evaluate AIDS (IeDEA) program

    PubMed Central

    Blevins, Meridith; Lindegren, Mary Lou; Yotebieng, Marcel; Nguyen, Dung Thi; Omondi, Alfred; Michael, Denna; Zannou, Djimon Marcel; Carriquiry, Gabriela; Pettit, April

    2017-01-01

    Objective Xpert MTB/RIF is recommended by the World Health Organization (WHO) as the initial tuberculosis (TB) diagnostic test in individuals suspected of HIV-associated TB. We sought to evaluate field implementation of Xpert among a cohort of HIV/TB co-infected individuals, including availability, utilization and outcomes. Design Observational cohort study (patient-level data) and cross-sectional study (site-level Xpert availability data). Methods Data were collected at 30 participating International epidemiologic Databases to Evaluate AIDS (IeDEA) sites in 18 countries from January 2012-January 2016. All patients were HIV-infected and diagnosed with TB, either bacteriologically or clinically, and followed until a determination of TB treatment outcome. We used multivariable modified Poisson regression to estimate adjusted relative risk (RR) and 95% confidence intervals for unfavorable TB treatment outcomes. Results Most sites (63%) had access to Xpert, either in the clinic (13%), in the same facility (20%) or offsite (30%). Among 2722 HIV/TB patients included, median age was 35.4 years and 41% were female; BMI and CD4 count were low. Overall, most patients (76%) received at least one TB test; 45% were positive. Only 4% of all patients were tested using Xpert: 64% were Xpert-positive, 13% showed rifampicin (RIF) resistance and 30% were extrapulmonary (EPTB) or both pulmonary-EPTB. Treatment outcomes were mostly favorable (77%) and we found little association between Xpert use and an unfavorable TB treatment outcome (RR 1.25, 95%CI: 0.83, 1.90). Conclusions In this cohort, Xpert utilization was low even though the majority of sites had access to the test. Our findings show the need for expanded implementation and further research exploring barriers to use in low-resource settings. PMID:28182705

  17. Measuring the efficiency of the Greek rural primary health care using a restricted DEA model; the case of southern and western Greece.

    PubMed

    Oikonomou, Nikolaos; Tountas, Yannis; Mariolis, Argiris; Souliotis, Kyriakos; Athanasakis, Kostas; Kyriopoulos, John

    2016-12-01

    This is a study to measure the efficiency of the rural Health Centres (HCs) and their Regional Surgeries (RSs) of the 6th Health Prefecture (HP) of Greece, which covers Southern and Western Greece. Data Envelopment Analysis (DEA) was applied under Constant and Variable Returns to Scale, using a weight-restricted, output-oriented model, to calculate pure technical efficiency (PΤΕ), scale efficiency (SE) and total technical efficiency (TE). The selection of inputs, outputs and their relative weights in the model was based on two consecutive consensus panels of experts on Primary Health Care (PHC). Medical personnel, nursing personnel and technological equipment were chosen as inputs and were attributed appropriate weight restrictions. Acute, chronic and preventive consultations where chosen as outputs; each output was constructed by smaller subcategories of different relative importance. Data were collected through a questionnaire sent to all HCs of the covered area. From the 42 HCs which provided complete data, the study identified 9 as technical efficient, 5 as scale efficient and 2 as total efficient. The mean TE, PTE and SE scores of the HCs of the 6th Health Prefecture were 0.57, 0.67 and 0.87, respectively. The results demonstrate noteworthy variation in efficiency in the productive process of the HCs of Southern and Western Greece. The dominant form of inefficiency was technical inefficiency. The HCs of the 6th HP can theoretically produce 33 % more output on average, using their current production factors. These results indicated potential for considerable efficiency improvement in most rural health care units. Emphasis on prevention and chronic disease management, as well as wider structural and organisational reforms, are discussed from the viewpoint of how to increase efficiency.

  18. Effect of Ag+ and PO43- ratios on the microstructure and photocatalytic activity of Ag3PO4

    NASA Astrophysics Data System (ADS)

    Qin, Jiaqian; Zhang, Xinyu; Yang, Chengwu; Song, Aijun; Zhang, Bing; Rajendran, Saravanan; Ma, Mingzhen; Liu, Riping

    2016-09-01

    In this work, the catalyst silver phosphate (Ag3PO4) with different initial ratios of Ag+ and PO43- in aqueous solution was synthesized by a simple precipitation method from AgNO3 and NH4H2PO4 which were used as the precursor. After that, the prepared samples were characterized by different techniques such as field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (UV-DRS) and decomposition evolution of rhodamine B (RhB) solution. The results indicate that the initial ratios of Ag+/PO43- in aqueous solution can modify the morphology and also it can significantly affect the photocatalytic performance. During photocatalytic process, the rich Ag+ ion Ag3PO4 can form the surface plasmon resonance (SPR) of Ag nanoparticles, which inhibit the reduction of Ag3PO4 resulting in higher photocatalytic activity and stability.

  19. The electron paramagnetic resonance spectrum of Ag2 3

    NASA Astrophysics Data System (ADS)

    van der Pol, A.; Reijersen, E. J.; de Boer, E.; Wasowicz, T.; Michalik, J.

    A highly resolved EPR spectrum of the silver trimer 109Ag2+3, present in 109Ag1-NaA zeolite, has been measured. The spectrum is characterized by an axially symmetric spin Hamiltonian having and for each of the 109Ag nuclei tMPH0037_images.

  20. AGS experiments -- 1996, 1997, 1998, 1999. Fifteenth edition

    SciTech Connect

    Lo Presti, P.

    1999-03-01

    This report is a compilation of two-page summaries for AGS experiments for FY 1996, FY 1997, FY 1998, FY 1999. The bulk of the experiments are for high energy physics and nuclear physics programs. Also included are the run schedules for the AGS for each of those years and a listing of publications of AGS experiments for 1982--1999.

  1. Development of a Rhizoctonia solani AG1-IB Specific Gene Model Enables Comparative Genome Analyses between Phytopathogenic R. solani AG1-IA, AG1-IB, AG3 and AG8 Isolates.

    PubMed

    Wibberg, Daniel; Rupp, Oliver; Blom, Jochen; Jelonek, Lukas; Kröber, Magdalena; Verwaaijen, Bart; Goesmann, Alexander; Albaum, Stefan; Grosch, Rita; Pühler, Alfred; Schlüter, Andreas

    2015-01-01

    Rhizoctonia solani, a soil-born plant pathogenic basidiomycetous fungus, affects various economically important agricultural and horticultural crops. The draft genome sequence for the R. solani AG1-IB isolate 7/3/14 as well as a corresponding transcriptome dataset (Expressed Sequence Tags--ESTs) were established previously. Development of a specific R. solani AG1-IB gene model based on GMAP transcript mapping within the eukaryotic gene prediction platform AUGUSTUS allowed detection of new genes and provided insights into the gene structure of this fungus. In total, 12,616 genes were recognized in the genome of the AG1-IB isolate. Analysis of predicted genes by means of different bioinformatics tools revealed new genes whose products potentially are involved in degradation of plant cell wall components, melanin formation and synthesis of secondary metabolites. Comparative genome analyses between members of different R. solani anastomosis groups, namely AG1-IA, AG3 and AG8 and the newly annotated R. solani AG1-IB genome were performed within the comparative genomics platform EDGAR. It appeared that only 21 to 28% of all genes encoded in the draft genomes of the different strains were identified as core genes. Based on Average Nucleotide Identity (ANI) and Average Amino-acid Identity (AAI) analyses, considerable sequence differences between isolates representing different anastomosis groups were identified. However, R. solani isolates form a distinct cluster in relation to other fungi of the phylum Basidiomycota. The isolate representing AG1-IB encodes significant more genes featuring predictable functions in secondary metabolite production compared to other completely sequenced R. solani strains. The newly established R. solani AG1-IB 7/3/14 gene layout now provides a reliable basis for post-genomics studies.

  2. MeProRisk - Acquisition and Prediction of thermal and hydraulic properties

    NASA Astrophysics Data System (ADS)

    Arnold, J.; Mottaghy, D.; Pechnig, R.

    2009-04-01

    MeProRisk is a joint project of five university institutes at RWTH Aachen University, Free University Berlin, and Kiel University. Two partners, namely Geophysica Beratunggesellschaft mbH (Aachen) and RWE Dea AG (Hamburg) present the industrial side. It is funded by the German Ministry of Education and Science (BMBF). The MeProRisk project aims to improve strategies to reduce the risk for planning geothermal power plants. Within our subproject we estimate geothermal relevant parameters in the laboratory and in the borehole scale. This basis data will be integrated with hydraulic and seismic experiments to provide a 3D reservoir model. Hitherto we focussed on two different type locations in Germany. These are (1) the crystalline basement in South Germany and (2) the Rotliegend formation and volcanic rocks in the Northern German Sedimentary Basin. In the case of the crystalline basement an extensive dataset could be composed from the 9 km deep KTB borehole including logging, core and cutting data. The whole data could be interpreted with respect to lithology, structure and alteration of the formation which mainly consists of alternating sequences of gneiss and metabasite. For the different rock types the data was analyzed statistically to provide specific values for geothermal key parameters. Important key parameters are for example: p-wave velocity, density, thermal conductivity, permeability and porosity. For the second type location we used logging data recovered within one borehole (> 5 km deep) which was drilled in the so called Voelkersen gas field. The data was supplied by the RWE DEA company. The formation comprises volcanic rocks and sandstones. On corresponding cores we measured p-wave velocity, thermal conductivity, density and porosity in the laboratory. In the same way as for type location (1) the complete data set was analyzed statistically to derive specific values which are relevant for the geothermal reservoir model. Finally this study will end up in

  3. Antibacterial Ag/a-C nanocomposite coatings: The influence of nano-galvanic a-C and Ag couples on Ag ionization rates

    NASA Astrophysics Data System (ADS)

    Manninen, N. K.; Calderon, S.; Carvalho, I.; Henriques, M.; Cavaleiro, A.; Carvalho, S.

    2016-07-01

    Biofilm formation has been pointed as a major concern in different industrial applications, namely on biomedical implants and surgical instruments, which has prompted the development of new strategies for production of efficient antimicrobial surfaces. In this work, nano-galvanic couples were created to enhance the antibacterial properties of silver, by embedding it into amorphous carbon (a-C) matrix. The developed Ag/a-C nanocomposite coatings, deposited by magnetron sputtering, revealed an outstanding antibacterial activity against Staphylococcus epidermidis, promoting a total reduction in biofilm formation with no bacteria counts in all dilution. The open circuit potential (OCP) tests in 0.9% NaCl confirmed that a-C shows a positive OCP value, in contrast to Ag coating, thus enhancing the ionization of biocidal Ag+ due to the nano-galvanic couple activation. This result was confirmed by the inductively coupled plasma-optical emission spectroscopy (ICP-OES), which revealed a higher Ag ionization rate in the nanocomposite coating in comparison with the Ag coating. The surface of Ag/a-C and Ag coatings immersed in 0.9% NaCl were monitored by scanning electron microscopy (SEM) over a period of 24 h, being found that the Ag ionization determined by ICP-OES was accompanied by an Ag nanoparticles coalescence and agglomeration in Ag/a-C coating.

  4. Water repellent Ag/Ag2O@bamboo cellulose fiber membrane as bioinspired cargo carriers.

    PubMed

    Wang, Yaru; Zhang, Ximu; Zhang, Xiaofang; Zhao, Jiangqi; Zhang, Wei; Lu, Canhui

    2015-11-20

    Water striders can walk on water. To mimic this function, a porous membrane consisted of bamboo cellulose fiber was hybridized with Ag/Ag2O nanoparticles through a facile in situ method to produce water repellent and well-ventilated materials. Herein, we report the sole surface roughness created by Ag/Ag2O nanoparticles could render the membrane a water contact angle (CA) of 140±3.0°. When floating on water, the hybrid membrane was able to support a heavy load more than 10 times the weight of the membrane itself. Additionally, this membrane demonstrated capabilities for oil sampling under water or oil/water separation and strong antibacterial activity against Escherichia coli. Thus we foresee that this novel hybrid membrane can be potentially utilized as drag-reducing, gas permeable and antibiotic substrates for constructing miniature aquatic devices.

  5. Selectivity control of photosensitivity of Ag-GaP and Ag- AlGaN structures

    NASA Astrophysics Data System (ADS)

    Lamkin, I. A.; Tarasov, S. A.; Solomonov, A. V.; Andreev, M. Y.; Kurin, S. Yu

    2015-12-01

    Design, growth and studies of photosensitive structures based on Ag-GaP and Ag- AlxGa1-xN contacts are reported. Methods for structure selectivity control, which allow changing the sensitivity spectrum half-width in a range of 11-210 nm were worked out. By varying the metal layer thickness, a set of Ag-GaP short-wavelength photodetectors (PD) was fabricated. The set includes PDs from broadband (spectrum half-width Δλ=210 nm, sensitivity SI = 0,19 A/W) to visible-blind (Δλ=15 nm, SI = 0,034 A/W). The use of Ag-AlxGa1-xN structures provided increased sensitivity (SI = 0,071 A/W) and Δλ reduced to 11 nm due to special selection of solid solution composition.

  6. Communication: Kinetics of chemical ordering in Ag-Au and Ag-Ni nanoalloys

    NASA Astrophysics Data System (ADS)

    Calvo, F.; Fortunelli, A.; Negreiros, F.; Wales, D. J.

    2013-09-01

    The energy landscape and kinetics of medium-sized Ag-Au and Ag-Ni nanoalloy particles are explored via a discrete path sampling approach, focusing on rearrangements connecting regions differing in chemical order. The highly miscible Ag27Au28 supports a large number of nearly degenerate icosahedral homotops. The transformation from reverse core-shell to core-shell involves large displacements away from the icosahedron through elementary steps corresponding to surface diffusion and vacancy formation. The immiscible Ag42Ni13 naturally forms an asymmetric core-shell structure, and about 10 eV is required to extrude the nickel core to the surface. The corresponding transformation occurs via a long and smooth sequence of surface displacements. For both systems the rearrangement kinetics exhibit Arrhenius behavior. These results are discussed in the light of experimental observations.

  7. High Resolution PDF Measurements on Ag Nanoparticles

    SciTech Connect

    Rocha, Tulio C. R.; Martin, Chris; Kycia, Stefan; Zanchet, Daniela

    2009-01-29

    The quantitative analysis of structural defects in Ag nanoparticles was addressed in this work. We performed atomic scale structural characterization by a combination of x-ray diffraction (XRD) using the Pair Distribution Function analysis (PDF) and High Resolution Transmission Electron Microscopy (HRTEM). The XRD measurements were performed using an innovative instrumentation setup to provide high resolution PDF patterns.

  8. Accuracy Assessment for AG500, Electromagnetic Articulograph

    ERIC Educational Resources Information Center

    Yunusova, Yana; Green, Jordan R.; Mefferd, Antje

    2009-01-01

    Purpose: The goal of this article was to evaluate the accuracy and reliability of the AG500 (Carstens Medizinelectronik, Lenglern, Germany), an electromagnetic device developed recently to register articulatory movements in three dimensions. This technology seems to have unprecedented capabilities to provide rich information about time-varying…

  9. 77 FR 63905 - Self-Regulatory Organizations; ICE Clear Credit LLC; Notice of Filing of Proposed Rule Change To...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-17

    ... GRID PLC; Portugal Telecom International Finance B.V.; RWE Aktiengesellschaft; TELECOM ITALIA SPA... PLC; Vattenfall Aktiebolag; VEOLIA ENVIRONNEMENT VIVENDI; VODAFONE GROUP PUBLIC LIMITED COMPANY...; ArcelorMittal; BASF SE; Glencore International AG; Henkel AG & Co. KGaA; Koninklijke DSM N.V.;...

  10. 77 FR 76156 - Self-Regulatory Organizations; ICE Clear Credit LLC; Notice of Filing of Proposed Rule Change To...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-26

    ....; Koninklijke KPN N.V.; NATIONAL GRID PLC; Portugal Telecom International Finance B.V.; RWE Aktiengesellschaft... Aktiebolag; UNITED UTILITIES PLC; Vattenfall Aktiebolag; VEOLIA ENVIRONNEMENT; VIVENDI; VODAFONE GROUP PUBLIC....; Anglo American plc; ArcelorMittal; BASF SE; Glencore International AG; Henkel AG & Co. KGaA;...

  11. Energy loss of 107Ag, 109Ag, and 150Sm in Ni and Au

    NASA Astrophysics Data System (ADS)

    Ribas, R. V.; Seale, W. A.; Roney, W. A.; Szanto, E. M.

    1980-04-01

    The stopping pow´er of 107Ag, 109Ag, and 150Sm in nickel and gold was measured as a preliminary test of a new technique for measuring energy loss based on the γ-ray Doppler shift. The analysis of the data was based on the theories of Lindhard, Scharff, and Schiott for nuclear and electronic stopping. The results are compared with the semiempirical predictions of Northcliffe and Schilling and the Lindhard-Scharff-Schiott theory.

  12. A dry method to synthesize dendritic Ag2Se nanostructures utilizing CdSe quantum dots and Ag thin films

    NASA Astrophysics Data System (ADS)

    Hu, Lian; Zhang, Bingpo; Xu, Tianning; Li, Ruifeng; Wu, Huizhen

    2015-01-01

    Dendritic Ag2Se nanostructures are synthesized in a dry environment by UV irradiating the hybrids composed of CdSe quantum dots (QDs) and silver (Ag). UV irradiation on CdSe QDs induces a photooxidation effect on the QD surface and leads to the formation of SeO2 components. Then SeO2 reacts with the Ag atoms in either Ag film or QD layer to produce the Ag2Se. The growth mechanism of Ag2Se dendrites on solid Ag films is explored and explained by a diffusion limited aggregation model in which the QD layer provides enough freedom for Ag2Se motion. Since the oxidation of the CdSe QDs is the critical step for the Ag2Se dendrites formation this dry chemical interaction between QDs and Ag film can be applied in the study of the QD surface chemical properties. With this dry synthesis method, the Ag2Se dendrites can also be facilely formed at the designed area on Ag substrates.

  13. A dry method to synthesize dendritic Ag2Se nanostructures utilizing CdSe quantum dots and Ag thin films.

    PubMed

    Hu, Lian; Zhang, Bingpo; Xu, Tianning; Li, Ruifeng; Wu, Huizhen

    2015-01-09

    Dendritic Ag2Se nanostructures are synthesized in a dry environment by UV irradiating the hybrids composed of CdSe quantum dots (QDs) and silver (Ag). UV irradiation on CdSe QDs induces a photooxidation effect on the QD surface and leads to the formation of SeO2 components. Then SeO2 reacts with the Ag atoms in either Ag film or QD layer to produce the Ag2Se. The growth mechanism of Ag2Se dendrites on solid Ag films is explored and explained by a diffusion limited aggregation model in which the QD layer provides enough freedom for Ag2Se motion. Since the oxidation of the CdSe QDs is the critical step for the Ag2Se dendrites formation this dry chemical interaction between QDs and Ag film can be applied in the study of the QD surface chemical properties. With this dry synthesis method, the Ag2Se dendrites can also be facilely formed at the designed area on Ag substrates.

  14. New insight into daylight photocatalysis of AgBr@Ag: synergistic effect between semiconductor photocatalysis and plasmonic photocatalysis.

    PubMed

    Jiang, Jing; Li, Hao; Zhang, Lizhi

    2012-05-14

    Noble metal nanoparticles (NPs) are often used as electron scavengers in conventional semiconductor photocatalysis to suppress electron-hole (e(-)-h(+) ) recombination and promote interfacial charge transfer, and thus enhance photocatalytic activity of semiconductors. In this contribution, it is demonstrated that noble metal NPs such as Ag NPs function as visible-light harvesting and electron-generating centers during the daylight photocatalysis of AgBr@Ag. Novel Ag plasmonic photocatalysis could cooperate with the conventional AgBr semiconductor photocatalysis to enhance the overall daylight activity of AgBr@Ag greatly because of an interesting synergistic effect. After a systematic investigation of the daylight photocatalysis mechanism of AgBr@Ag, the synergistic effect was attributed to surface plasmon resonance induced local electric field enhancement on Ag, which can accelerate the generation of e(-)-h(+) pairs in AgBr, so that more electrons are produced in the conduction band of AgBr under daylight irradiation. This study provides new insight into the photocatalytic mechanism of noble metal/semiconductor systems as well as the design and fabrication of novel plasmonic photocatalysts.

  15. Advances of Ag, Cu, and Ag-Cu alloy nanoparticles synthesized via chemical reduction route

    NASA Astrophysics Data System (ADS)

    Tan, Kim Seah; Cheong, Kuan Yew

    2013-04-01

    Silver (Ag) and copper (Cu) nanoparticles have shown great potential in variety applications due to their excellent electrical and thermal properties resulting high demand in the market. Decreasing in size to nanometer scale has shown distinct improvement in these inherent properties due to larger surface-to-volume ratio. Ag and Cu nanoparticles are also shown higher surface reactivity, and therefore being used to improve interfacial and catalytic process. Their melting points have also dramatically decreased compared with bulk and thus can be processed at relatively low temperature. Besides, regularly alloying Ag into Cu to create Ag-Cu alloy nanoparticles could be used to improve fast oxidizing property of Cu nanoparticles. There are varieties methods have been reported on the synthesis of Ag, Cu, and Ag-Cu alloy nanoparticles. This review aims to cover chemical reduction means for synthesis of those nanoparticles. Advances of this technique utilizing different reagents namely metal salt precursors, reducing agents, and stabilizers, as well as their effects on respective nanoparticles have been systematically reviewed. Other parameters such as pH and temperature that have been considered as an important factor influencing the quality of those nanoparticles have also been reviewed thoroughly.

  16. A comparative study about electronic structures at rubrene/Ag and Ag/rubrene interfaces

    SciTech Connect

    Sinha, Sumona Mukherjee, M.

    2015-10-15

    The contact between the electrode and the organic semiconductor is one of the most crucial factors in determining the organic device performance. The development and production technology of different organic devices require the understanding of different types of metal/organic semiconducting thin film interfaces. Comparisons about the electronic structures at Rubrene/Ag and Ag/Rubrene interfaces have been studied using photoemission spectroscopy. The Ag on rubrene interfaces is found to show more interesting and complex natures than its counterpart. The vacuum level (VL) was shifted about 0.51 eV from push back effect for deposition of 5 Å rubrene onto Ag film whereas the electronic features of silver was only suppressed and no energy shift was resulted. While the deposition of 5 Å Ag onto rubrene film leads to the diffusion of the Ag atoms, as a cluster with quantum size effect, inside the film. Angle dependent XPS measurement indicates that diffused metal clusters were present at entire probed depth of the film. Moreover these clusters dope the uppermost surface of the rubrene film which consequences a shift of the electronic states of thick organic film towards higher binding energy. The VL was found to shift about 0.31 eV toward higher binding energy whereas the shift was around 0.21 eV for the electronic states of rubrene layer.

  17. Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

    SciTech Connect

    Kumaran, R.; Alagar, M.; Dinesh Kumar, S.; Subramanian, V.; Dinakaran, K.

    2015-09-14

    We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.

  18. The Effect of Ag and Ag+N Ion Implantation on Cell Attachment Properties

    SciTech Connect

    Urkac, Emel Sokullu; Oztarhan, Ahmet; Gurhan, Ismet Deliloglu; Iz, Sultan Gulce; Tihminlioglu, Funda; Oks, Efim; Nikolaev, Alexey; Ila, Daryush

    2009-03-10

    Implanted biomedical prosthetic devices are intended to perform safely, reliably and effectively in the human body thus the materials used for orthopedic devices should have good biocompatibility. Ultra High Molecular Weight Poly Ethylene (UHMWPE) has been commonly used for total hip joint replacement because of its very good properties. In this work, UHMWPE samples were Ag and Ag+N ion implanted by using the Metal-Vapor Vacuum Arc (MEVVA) ion implantation technique. Samples were implanted with a fluency of 1017 ion/cm2 and extraction voltage of 30 kV. Rutherford Backscattering Spectrometry (RBS) was used for surface studies. RBS showed the presence of Ag and N on the surface. Cell attachment properties investigated with model cell lines (L929 mouse fibroblasts) to demonstrate that the effect of Ag and Ag+N ion implantation can favorably influence the surface of UHMWPE for biomedical applications. Scanning electron microscopy (SEM) was used to demonstrate the cell attachment on the surface. Study has shown that Ag+N ion implantation represents more effective cell attachment properties on the UHMWPE surfaces.

  19. Preparation of Ag@Ag₃PO₄@ZnO ternary heterostructures for photocatalytic studies.

    PubMed

    Jin, Chao; Liu, Guanglei; Zu, Lianhai; Qin, Yao; Yang, Jinhu

    2015-09-01

    In this article, we report a novel Ag@Ag3PO4@ZnO ternary heterostructures synthesized through a three-step approach. Firstly, single-crystalline Ag nanorods are fabricated and served as the templates for subsequent Ag3PO4 deposition. Secondly, Ag3PO4 crystals are grown around Ag core nanorods through a solution co-precipitation process, leading to the Ag@Ag3PO4 binary heterostructures. Finally, ZnO nanorod arrays on the surface of the Ag@Ag3PO4 heterostructures are realized via a seeded growth strategy, forming the typical Ag@Ag3PO4@ZnO ternary heterostructures. The photodegradation of rhodamine B under ultraviolet-visible light irradiation indicates that the Ag@Ag3PO4@ZnO ternary heterostructures exhibit much higher activities than pure Ag3PO4 and binary heterostructures of Ag@Ag3PO4. The higher photocatalytic activity of the Ag@Ag3PO4@ZnO composites may be attributed to the effective photogenerated charge separation at heterointerfaces of Ag/Ag3PO4 and Ag3PO4/ZnO, and the rapid electron transport along one-dimensional Ag and ZnO nanorods.

  20. Enhanced thermal stability of Ag nanorods through capping

    SciTech Connect

    Bachenheimer, Lou; Elliott, Paul; Stagon, Stephen; Huang, Hanchen

    2014-11-24

    Ag nanorods may serve as sensors in the detection of trace amounts of chemical agents, even single molecules, through surface enhanced Raman spectroscopy (SERS). However, thermal coarsening of Ag nanorods near room temperature limits their applications. This letter proposes the use of a thin oxide capping layer to enhance the thermal stability of Ag nanorods beyond 100 °C. Using electron microscopy characterization and SERS tests, the authors show that the proposed method is effective in stabilizing both morphology and sensitivity of Ag nanorods. The results of this work extend the applicability of Ag nanorods as chemical sensors to higher temperatures.

  1. Investigating the properties of infrared PCFs based on AgCl-AgBr, AgBr-TlI, AgCl-AgBr-AgI(TlI) crystals theoretically and experimentally

    NASA Astrophysics Data System (ADS)

    Korsakov, A. S.; Zhukova, L. V.; Vrublevsky, D. S.; Korsakova, E. A.

    2014-12-01

    For operating at the CO2 laser wavelength (10.6 μm), we manufactured single- and double-layered infrared (IR) fibers, as well as those with an enlarged mode field diameter, obtained via extrusion from Ag(Cl) x Br1 - x (0 < x < 1), Ag1 - x Tl x Br1 - x I x (0 < x ≤ 0.08), Ag1 - x Tl x Cl y I z Br1 - y - z (0.003 ≤ x ≤ 0.040; 0.066 ≤ y ≤ 0.246; 0.004 ≤ z ≤ 0.048) crystals. We calculated their fundamental characteristics at 10.6 μm and conducted computer simulation of their structure and mode field beforehand. Optical and mechanical characteristics of IR crystals and fibers, such as transmission range, refractive indices, and durability, were also determined, with the dependence of varying monadic thallium iodide content on them being shown as well. In particular, we demonstrated that the increase of thallium iodide content in the initial silver chloride bromide widens the transparency range to 40 μm and improves the rupture strength up to 200 MPa, which is due to the decrease in average fiber grain size up to 95 nm—nanocrystalline size. Using a CCD camera for the far field investigation at 10.6 μm, we showed the single mode of the fibers obtained.

  2. Biotic and abiotic interactions in aquatic microcosms determine fate and toxicity of Ag nanoparticles: part 2-toxicity and Ag speciation.

    PubMed

    Bone, Audrey J; Colman, Benjamin P; Gondikas, Andreas P; Newton, Kim M; Harrold, Katherine H; Cory, Rose M; Unrine, Jason M; Klaine, Stephen J; Matson, Cole W; Di Giulio, Richard T

    2012-07-03

    To study the effects of complex environmental media on silver nanoparticle (AgNP) toxicity, AgNPs were added to microcosms with freshwater sediments and two species of aquatic plants (Potamogeton diversifolius and Egeria densa), followed by toxicity testing with microcosm surface water. Microcosms were designed with four environmental matrices in order to determine the contribution of each environmental compartment to changes in toxicity: water only (W), water + sediment (WS), water + plants (WP), and water + plants + sediment (WPS). Silver treatments included AgNPs with two different coatings, gum arabic (GA-AgNPs) or polyvinylpyrollidone (PVP-AgNPs), as well as AgNO(3). Water samples taken from the microcosms at 24 h postdosing were used in acute toxicity tests with two standard model organisms, early life stage zebrafish (Danio rerio) and Daphnia magna. Speciation of Ag in these samples was analyzed using Ag L3-edge X-ray absorption near edge spectroscopy (XANES). Silver speciation patterns for the nanoparticle treatments varied significantly by coating type. While PVP-AgNPs were quite stable and resisted transformation across all matrices (>92.4% Ag(0)), GA-AgNP speciation patterns suggest significantly higher transformation rates, especially in treatments with plants (<69.2% and <58.8% Ag(0) in WP and WPS, respectively) and moderately increased transformation with sediments (<85.6% Ag(0)). Additionally, the presence of plants in the microcosms (with and without sediments) reduced both the concentration of Ag in the water column and toxicity for all Ag treatments. Reductions in toxicity may have been related to decreased water column concentrations as well as changes in the surface chemistry of the particles induced by organic substances released from the plants.

  3. Ag@Ag8W4O16 nanoroasted rice beads with photocatalytic, antibacterial and anticancer activity.

    PubMed

    Selvamani, Muthamizh; Krishnamoorthy, Giribabu; Ramadoss, Manigandan; Sivakumar, Praveen Kumar; Settu, Munusamy; Ranganathan, Suresh; Vengidusamy, Narayanan

    2016-03-01

    Increasing resistance of pathogens and cancer cell line towards antibiotics and anticancer agents has caused serious health problems in the past decades. Due to these problems in recent years, researchers have tried to combine nanotechnology with material science to have intrinsic antimicrobial and anticancer activity. The metals and metal oxides were investigated with respect to their antimicrobial and anticancer effects towards bacteria and cancer cell line. In the present work metal@metal tungstate (Ag@Ag8W4O16 nanoroasted rice beads) is investigated for antibacterial activity against Escherichia coli and Staphylococcus aureus using Mueller-Hinton broth and the anticancer activity against B16F10 cell line was studied. Silver decorated silver tungstate (Ag@Ag8W4O16) was synthesized by the microwave irradiation method using Cetyl Trimethyl Ammonium Bromide (CTAB). Ag@Ag8W4O16 was characterized by using various spectroscopic techniques. The phase and crystalline nature were analyzed by using XRD. The morphological analysis was carried out using Field Emission Scanning Electron Microscopy (FE-SEM), and High Resolution Transmission Electron Microscopy (HR-TEM). Further, Fourier Transform Infrared Spectroscopy (FT-IR) and Raman spectral analysis were carried out in order to ascertain the presence of functional groups in Ag@Ag8W4O16. The optical property was investigated using Diffuse Reflectance Ultraviolet-Visible Spectroscopy (DRS-UV-Vis) and the band gap was found to be 3.08eV. Surface area of the synthesized Ag@Ag8W4O16 wasanalyzed by BET analysis and Ag@Ag8W4O16 was utilized for the degradation of organic dyes methylene blue and rhodamine B. The morphology of the Ag@Ag8W4O16 resembles roasted rice beads with breath and length in nm range. The oxidation state of tungsten (W) and silver (Ag) was investigated using X-ray photoelectron spectroscopy (XPS).

  4. Nanojoining of crossed Ag nanowires: a molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Cui, Jianlei; Wang, Xuewen; Barayavuga, Theogene; Mei, Xuesong; Wang, Wenjun; He, Xiaoqiao

    2016-07-01

    Ag nanowires are considered to be the promising candidates for future electronic circuit owing to the excellent electrical and thermal properties, with the miniaturization of electronics devices into nanometer scale. Though interconnect technology between Ag nanowires (Ag NWs) is essential for nanofunctional devices, it lacks sufficient experimental data. Besides, the determination of Ag NW interconnection configuration is experimentally difficult to do for lacking the sufficient investigation of atomic configuration evolution during nanojoining process. So the nanojoining between the crossed Ag NWs with the same diameter of 2 nm and different lengths was performed by molecular dynamics simulation to explain the unclear nanojoining mechanism based on thermal effect. As the simulation results present, when the nanojoining temperature is relatively high, though the Ag NWs are connected with the interpenetration effect of Ag atoms at the crossed nanojunction area, the nanostructures of Ag NWs have been seriously deformed with shorter length and larger diameter, showing relatively more obvious melting characteristics based on the chaotic atomic structures. If the temperature is reduced to 300 K as cold welding, the crossed Ag NWs can be partially contacted with the partial mixture of Ag atoms, and the interstices always exist between the Si surface and the upper Ag nanowire. In addition, the obvious dislocation phenomenon will appear and evolve as time goes on. Consequently, the dominant mechanism was revealed for providing a fundamental understanding of how `hot' and `cold' welding technology affects the atomic contact configuration, respectively.

  5. A novel hexanuclear silver(I) cluster containing a regular Ag6 ring with short Ag-Ag distances and an argentophilic interaction.

    PubMed

    Barreiro, Elena; Casas, José S; Couce, María D; Laguna, Antonio; López-de-Luzuriaga, José M; Monge, Miguel; Sánchez, Agustin; Sordo, José; Vázquez López, Ezequiel M

    2013-04-28

    The hexanuclear complex [HQ][Ag(p-mpspa)] (H2-p-mpspa = 3-(4-methoxyphenyl)-2-sulfanylpropenoic acid) was prepared by reacting the precursor [Ag(H-p-mpspa)] with diisopropylamine (Q). The complex was characterized by spectroscopic techniques and the structure was solved by a single crystal X-ray diffraction study. The crystal contains hydrogen-bonded diisopropylammonium cations and [Ag6(p-mpspa)6](6-) anions that are based on a regular Ag6 ring with each S-donor atom of the sulfanylcarboxylate ligand bridging two Ag atoms. The Ag-Ag bond distances, 2.8036(6) Å, are very short and suggest a closed shell d(10)···d(10) argentophilic interaction. To analyze the relative role of this interaction and that of the S-bridging atom the anionic [Ag6(p-mpspa)6](6-) moiety has been studied theoretically at the Hartree-Fock (HF) and 2(nd) order Møller-Plesset perturbation theory (MP2) levels on a very simple [Ag6(SH)6] A model system. A large model system [Ag6(p-mpspa)6](6-)B has also been studied by applying the ONIOM (QM/MM) approach using HF/UFF and MP2/UFF combinations as levels of theory. The six experimentally observed Ag(I)···Ag(I) supported interactions are reproduced when dispersion-type interactions are considered in the theory levels MP2 and ONIOM MP2/UFF for models A and B, respectively. The use of HF and ONIOM HF/UFF levels led to a similar hexanuclear structure but displayed a large hexagonal disposition without argentophilic contacts for both models A and B. The steric hindrance exerted by the ligands did not preclude the formation of argentophilic interactions, as observed experimentally.

  6. RRR and thermal conductivity of Ag and Ag-0.2 wt.%Mg alloy in Ag/Bi-2212 wires

    NASA Astrophysics Data System (ADS)

    Li, P.; Ye, L.; Jiang, J.; Shen, T.

    2015-12-01

    Residual resistivity ratio (RRR) and thermal conductivity of metal matrix in metal/superconductor composite wires are important parameters for designing superconducting magnets. However, the resistivity of silver in reacted Ag/Bi-2212 wires has yet to be determined over temperature range from 4.2 K to 80 K because Bi-2212 filaments have a critical transition temperature Tc of ∼ 80 K, and because it is unknown whether the RRR of Ag/Bi-2212 degrades with Cu diffusing from Bi-2212 filaments into silver sheathes at elevated temperatures and to what degree it varies with heat treatment. We measured the resistivity of stand-alone Ag and AgMg (Ag-0.2 wt.% Mg) wires as well as the resistivity of Ag and Ag-0.2 wt.% Mg in Ag/Bi- 2212 round wires reacted in 1 bar oxygen at 890 °C for 1, 8, 24 and 48 hours and quickly cooled to room temperature. The heat treatment was designed to reduce the critical current Ic of Bi- 2212 wires to nearly zero while allowing Cu loss to fully manifest itself. We determined that pure silver exhibits a RRR of ∼ 220 while the oxide-dispersion strengthened Ag-Mg exhibits a RRR of ∼ 5 in stand-alone samples. A surprising result is that the RRR of silver in the composite round wires doesn't degrade with extended time at 890 °C for up to 48 hours. This surprising result may be explained by our observation that the Cu that diffuses into silver tends to form Cu2O precipitates in oxidizing atmosphere, instead of forming Ag-Cu solution alloy. We also measured the thermal conductivity and the magneto-resistivity of pure Ag and Ag-0.2 wt. % Mg from 4.2 K to 300 K in magnetic fields up to 14.8 T and summarized them using a Kohler plot.

  7. Interfacial Reactions in Sn-Ag/Co Couples

    NASA Astrophysics Data System (ADS)

    Chen, Sinn-wen; Chen, Tung-Kai; Chang, Jui-shen; Hsu, Chia-ming; Chen, Wei-An

    2014-02-01

    Sn-Ag alloys are important solders, and Co and Co alloys are investigated as barrier layers. Interfacial reactions in Sn-Ag/Co couples were examined in this study for Ag contents of 1.0 wt.%, 2.0 wt.%, and 3.5 wt.% and reaction temperatures of 250°C, 200°C, and 150°C. Only CoSn3 formed in Sn-Ag/Co couples reacted at 250°C, but both CoSn3 and Ag3Sn formed in couples reacted at 200°C and 150°C. The reaction layer was 100 μm thick in Sn-3.5 wt.%Ag/Co couples reacted at 200°C for 110 h. The reaction rates were lower if Ag was added, but remained very fast compared with those for Ni and Ni-based substrates.

  8. Photo-catalytic activity of Plasmonic Ag@AgCl nanoparticles (synthesized via a green route) for the effective degradation of Victoria Blue B from aqueous phase.

    PubMed

    Devi, Th Babita; Begum, Shamima; Ahmaruzzaman, M

    2016-07-01

    This study reports a green process for the fabrication of Ag@AgCl (silver@silver chloride) nanoparticles by using Aquilaria agallocha (AA) leaves juice without using any external reagents. The effect of various reaction parameters, such as reaction temperature, reaction time and concentration of Aquilaria agallocha leaves juice in the formation of nanoparticles have also been investigated. From the FTIR spectra of leaves juice and phytochemicals test, it was found that flavonoids present in the leaves are responsible for the reduction of Ag(+) ions to Ag(0) species and leads to the formation of Ag@AgCl NPs. The synthesized Ag@AgCl NPs were utilized for the removal of toxic and hazardous dyes, such as Victoria Blue B from aqueous phase. Approximately, 99.46% degradation of Victoria Blue B dye were observed with Ag@AgCl NPs. Furthermore, the photocatalytic activity of the Ag@AgCl nanoparticles was unchanged after 5cycles of operation.

  9. New frontiers in water purification: highly stable amphopolycarboxyglycinate-stabilized Ag-AgCl nanocomposite and its newly discovered potential

    NASA Astrophysics Data System (ADS)

    Krutyakov, Yurii A.; Zherebin, Pavel M.; Kudrinskiy, Alexey A.; Zubavichus, Yan V.; Presniakov, Mikhail Yu; Yapryntsev, Alexey D.; Karabtseva, Anastasia V.; Mikhaylov, Dmitry M.; Lisichkin, Georgii V.

    2016-09-01

    A simple synthetic procedure for high-stable dispersions of porous composite Ag/AgCl nanoparticles stabilized with amphoteric surfactant sodium tallow amphopolycarboxyglycinate has been proposed for the first time. The prepared samples were characterized by UV-vis spectroscopy, x-ray powder diffraction (XRD), x-ray photoelectron spectroscopy, small area electron diffraction (SAED), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and electron probe micro-analysis. In addition, measurements (carried out at the Kurchatov synchrotron radiation source stations) of the Ag K-edge extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) spectra and XRD of the prepared nanoparticles have been performed. The obtained results suggest that small-sized Ag clusters are homogeneously distributed in the mass of the AgCl nanoparticle (~80 nm) formed during the synthesis. The Ag/AgCl dispersion demonstrates photocatalytic activity (with respect to methyl orange) and high bactericidal activity against E. coli. This activity is superior to the activity of both Ag and AgCl nanoparticles stabilized by the same surfactant. Thus, porous composite Ag/AgCl nanoparticles can be used as a multifunctional agent that is able to remove both pollutants and bacterium from water.

  10. Sequestration of Ag(I) from aqueous solution as Ag(0) nanostructures by nanoscale zero valent iron (nZVI)

    NASA Astrophysics Data System (ADS)

    Zhang, Yalei; Yan, Jing; Dai, Chaomeng; Li, Yuting; Zhu, Yan; Zhou, Xuefei

    2015-11-01

    This study investigates the application of nanoparticle zero valent iron (nZVI) to sequester Ag(I) as Ag(0) nanostructures from aqueous solution. Batch experiments were performed with nZVI exposed to aqueous Ag(I) to investigate the effects of environmental parameters, including nZVI dose, temperature and pH. High temperature facilitates Ag(I) sequestration, and the rate constants are determined to be 0.02, 0.12, and 0.31 mg L/m2 at 30, 50, and 60 °C, respectively. Ag(I) sequestration was adversely affected by adding nitric acid to the solution due to significant acid washing, decreasing the available nZVI active sites. Characterization techniques including TEM, XRD, and HR-XPS revealed that nZVI is oxidized to lepidocrocite and magnetite/maghemite and confirmed the formation of nanocrystalline silver. HR-XPS analysis indicated that Ag2O forms rapidly as an intermediate due to Ag(I) adsorption onto the FeOOH layer. The Ag(0) nanostructures that are formed are fractal, spherical, and dendritic or rod-like, respectively, in morphology by FE-TEM images at different Ag/Fe mass ratios. A general reaction model for the interaction Ag(I) with nZVI is proposed. Our results suggest that nZVI is effective for Ag(I) removal.

  11. Plasmonic Ag@AgCl nanotubes fabricated from copper nanowires as high-performance visible light photocatalyst.

    PubMed

    Sun, Lei; Zhang, Ruizhong; Wang, Yuan; Chen, Wei

    2014-09-10

    In this paper, plasmonic photocatalyst Ag@AgCl nanotubes were prepared by a cost-efficient and template-based method and their photocatalytic properties were studied. In the synthesis, copper nanowires were first synthesized and Ag nanotubes were then obtained through the galvanic reaction between copper and Ag ions. The formation of Ag@AgCl nanotubes was finally achieved by in situ oxidation reaction upon the addition of FeCl3. The crystal structure of the product was characterized by X-ray powder diffraction. The morphology and composition of the composite were studied by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements. All the structure characterizations showed that the tubulate product was produced by the synthetic processes. By using the obtained product as photocatalyst, the photodegradation of methyl orange (MO) was investigated under visible light. The experimental results showed that the as-prepared Ag@AgCl nanotubes exhibit excellent photocatalytic performance and high stability. Under visible light irradiation, more than 92.58% of the MO dye has been decomposed in 10 min on the product with a 1:1 ratio of Fe/Ag. On the basis of the proposed mechanism, the improved photocatalytic activities of the Ag@AgCl hybrids can be ascribed to the enhanced surface area for dye molecule adsorption, enhanced visible light absorbance, and the efficient charge separation of the hybrid nanostructures.

  12. Outcomes of antiretroviral therapy in children in Asia and Africa: a comparative analysis of the IeDEA pediatric multiregional collaboration

    PubMed Central

    Leroy, Valeriane; Malateste, Karen; Rabie, Helena; Lumbiganon, Pagakrong; Ayaya, Samuel; Dicko, Fatoumata; Davies, Mary-Ann; Kariminia, Azar; Wools-Kaloustian, Kara; Aka, Edmond; Phiri, Samuel; Aurpibul, Linda; Yiannoutsos, Constantin; Signaté-Sy, Haby; Mofenson, Lynne; Dabis, François

    2013-01-01

    Background We investigated 18-month incidence and determinants of death and loss-to-follow-up of children after antiretroviral therapy (ART) initiation in a multiregional collaboration in lower-income countries. Methods HIV-infected children (positive PCR <18 months or positive serology ≥18 months) from IeDEA cohorts, <16 years, initiating ART were eligible. A competing risk regression model was used to analyze the independent risk of two failure types: death and loss-to-follow-up (>6 months). Findings Data on 13611 children, from Asia (N=1454), East-Africa (N=3114), Southern-Africa (N=6212) and West-Africa (N=2881) contributed 20,417 person-years of follow-up. At 18 months, the adjusted risk of death was 4.3% in East-Africa, 5.4% in Asia, 5.7% in Southern-Africa and 7.4% in West-Africa (P=0.01). Age<24 months, WHO stage 4, CD4<10%, attending a private sector clinic, larger cohort size and living in West-Africa were independently associated with poorer survival. The adjusted risk of loss-to-follow-up was 4.1% in Asia, 9.0% in Southern-Africa, 14.0% in East-Africa, and 21.8% in West-Africa (P <0.01). Age<12 months, non NNRTI-based ART regimen, WHO stage 4 at ART start, ART initiation after 2005, attending a public sector or a non-urban clinic, having to pay for laboratory tests or antiretroviral drugs, larger cohort size, and living in East or West-Africa were significantly associated with higher loss-to-follow-up. Conclusion Findings differed substantially across regions but raise overall concerns about delayed ART start, low access to free HIV-services for children, and increased workload on program retention in lower-income countries. Universal free access to ART services and innovative approaches are urgently needed to improve pediatric outcomes at program level. PMID:23187940

  13. Mechanisms of Toxicity of Ag Nanoparticles in Comparison to Bulk and Ionic Ag on Mussel Hemocytes and Gill Cells.

    PubMed

    Katsumiti, Alberto; Gilliland, Douglas; Arostegui, Inmaculada; Cajaraville, Miren P

    2015-01-01

    Silver nanoparticles (Ag NPs) are increasingly used in many products and are expected to end up in the aquatic environment. Mussels have been proposed as marine model species to evaluate NP toxicity in vitro. The objective of this work was to assess the mechanisms of toxicity of Ag NPs on mussel hemocytes and gill cells, in comparison to ionic and bulk Ag. Firstly, cytotoxicity of commercial and maltose stabilized Ag NPs was screened in parallel with the ionic and bulk forms at a wide range of concentrations in isolated mussel cells using cell viability assays. Toxicity of maltose alone was also tested. LC50 values were calculated and the most toxic Ag NPs tested were selected for a second step where sublethal concentrations of each Ag form were tested using a wide array of mechanistic tests in both cell types. Maltose-stabilized Ag NPs showed size-dependent cytotoxicity, smaller (20 nm) NPs being more toxic than larger (40 and 100 nm) NPs. Maltose alone provoked minor effects on cell viability. Ionic Ag was the most cytotoxic Ag form tested whereas bulk Ag showed similar cytotoxicity to the commercial Ag NPs. Main mechanisms of action of Ag NPs involved oxidative stress and genotoxicity in the two cell types, activation of lysosomal AcP activity, disruption of actin cytoskeleton and stimulation of phagocytosis in hemocytes and increase of MXR transport activity and inhibition of Na-K-ATPase in gill cells. Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form. In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag.

  14. Mechanisms of Toxicity of Ag Nanoparticles in Comparison to Bulk and Ionic Ag on Mussel Hemocytes and Gill Cells

    PubMed Central

    Katsumiti, Alberto; Gilliland, Douglas; Arostegui, Inmaculada; Cajaraville, Miren P.

    2015-01-01

    Silver nanoparticles (Ag NPs) are increasingly used in many products and are expected to end up in the aquatic environment. Mussels have been proposed as marine model species to evaluate NP toxicity in vitro. The objective of this work was to assess the mechanisms of toxicity of Ag NPs on mussel hemocytes and gill cells, in comparison to ionic and bulk Ag. Firstly, cytotoxicity of commercial and maltose stabilized Ag NPs was screened in parallel with the ionic and bulk forms at a wide range of concentrations in isolated mussel cells using cell viability assays. Toxicity of maltose alone was also tested. LC50 values were calculated and the most toxic Ag NPs tested were selected for a second step where sublethal concentrations of each Ag form were tested using a wide array of mechanistic tests in both cell types. Maltose-stabilized Ag NPs showed size-dependent cytotoxicity, smaller (20 nm) NPs being more toxic than larger (40 and 100 nm) NPs. Maltose alone provoked minor effects on cell viability. Ionic Ag was the most cytotoxic Ag form tested whereas bulk Ag showed similar cytotoxicity to the commercial Ag NPs. Main mechanisms of action of Ag NPs involved oxidative stress and genotoxicity in the two cell types, activation of lysosomal AcP activity, disruption of actin cytoskeleton and stimulation of phagocytosis in hemocytes and increase of MXR transport activity and inhibition of Na-K-ATPase in gill cells. Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form. In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag. PMID:26061169

  15. A variable Ag-Cr-Oxalate channel lattice: [M(x)Ag(0.5)(-)(x)(H(2)O)(3)]@[Ag(2.5)Cr(C(2)O(4))(3)], M = K, Cs, Ag.

    PubMed

    Dean, Philip A W; Craig, Don; Dance, Ian; Russell, Vanessa; Scudder, Marcia

    2004-01-26

    Reaction of aqueous AgNO(3) with aqueous M(3)[Cr(ox)(3)] in >or=3:1 molar ratio causes the rapid growth of large, cherry-black, light-stable crystals which are not Ag(3)[Cr(ox)(3)], but [M(0.5)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)] (ox(2)(-) = oxalate, C(2)O(4)(2)(-); M = Na, K, Cs, Ag, or mixtures of Ag and a group 1 element). The structure of these crystals contains an invariant channeled framework, with composition [[Ag(2.5)Cr(ox)(3)](-)(0.5)]( infinity ), constructed with [Cr(ox)(3)] coordination units linked by Ag atoms through centrosymmetric [Cr-O(2)C(2)O(2)-Ag](2) double bridges. The framework composition [Ag(2.5)Cr(ox)(3)](-)(0.5) occurs because one Ag is located on a 2-fold axis. Within the channels there is a well-defined and ordered set of six water molecules, strongly hydrogen bonded to each other and some of the oxalate O atoms. This invariant channel plus water structure accommodates group 1 cations, and/or Ag cations, in different locations and in variable proportions, but always coordinated by channel water and some oxalate O atoms. The general formulation of these crystals is therefore [M(x)Ag(0.5-x)(H(2)O)(3)]@[Ag(2.5)Cr(ox)(3)]. Five different crystals with this structure are reported, with compositions 1 Ag(0.5)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 2 Cs(0.19)Ag(0.31)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 3 K(0.28)Ag(0.22)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), 4 Cs(0.41)Ag(0.09)[Ag(2.5)Cr(ox)(3)](H(2)O)(3), and 5 Cs(0.43)Ag(0.07) [Ag(2.5)Cr(ox)(3)](H(2)O)(3). All crystallize in space group C2/c, with a approximately 18.4, b approximately 14.6, c approximately 12.3 A, beta approximately 113 degrees. Pure Ag(3)[Cr(ox)(3)](H(2)O)(3), which has the same crystal structure (1), was obtained from water by treating Li(3)[Cr(ox)(3)] with excess AgNO(3). Complete dehydration of all of these compounds occurs between 30 and 100 degrees C, with loss of diffraction, but rehydration by exposure to H(2)O(g) at ambient temperature leads to recovery of the original diffraction pattern. In single

  16. PERFORMANCE OF THE AGS TRANSITION JUMP SYSTEM.

    SciTech Connect

    AHRENS,L.A.; BRENNAN,J.M.; GLENN,J.W.; ROSER,T.; VAN ASSELT,W.K.

    1999-03-29

    The transition jump system has been indispensable to the high intensity proton operation of the AGS complex. Nevertheless, transition crossing remains one of the major hurdles as the accelerator complex intensity is pushed upward. To enhance the performance of the system ''quadrupole pumping'' in the Booster is used to minimize the necessary longitudinal dilution of the beam on the AGS injection porch. During the transition jump sextupole correctors at strategic locations are pulsed to minimize the effects of the chromatic non-linearity of the jump system. The available instrumentation for diagnosing the performance of the system will be described, along with installed hardware to counter the non-linear effects of the transition jump system.

  17. Stability of magic planar Ag clusters

    NASA Astrophysics Data System (ADS)

    Chiu, Y. P.; Ou, Y. S.; Chang, Y. R.; Wei, C. M.; Chang, C. S.; Tsong, Tien T.

    2007-03-01

    The spontaneous assembly of atoms and molecules in a system has attracted many research interests and created numerous potential applications. Utilizing the periodic pattern found on the Pb quantum islands, which are grown on the Si(111) surface, we have recently discovered that self-organized Ag planar clusters formed on these templates exhibit enhanced stability at some particular sizes [1]. Existence of the magic atom numbers in these clusters is mainly attributed to the electronic confinement effect. Here, we further explore the strength of these magic clusters subject to the temperature rise and oxygen exposure. Detailed calculations based on ab initio density functional theory have also been performed. The results help establish the relation between the physical and chemical stability of a magic Ag cluster and its size and shape. Ref:[1] Ya-Ping Chiu, Li-Wei Huang, Ching-Ming Wei, Chia-Seng Chang, and Tien-Tzou Tsong, Phys. Rev. Lett. 97, 165504 (2006).

  18. Spots on AG Virginis - Paradigm or panacea?

    NASA Astrophysics Data System (ADS)

    Bell, S. A.; Rainger, P. P.; Hilditch, R. W.

    1990-12-01

    New photometric and spectroscopic observations of the eclipsing binary AG Vir are presented. Medium-resolution spectroscopy has allowed the measurement of velocities for the secondary component for the first time. The V light curve shows many of the features seen in previous studies of this system. A full analysis of the spectroscopic and photometric data has been made which suggests that the system is either in a marginal state of conatact or a deep-contact configuration depending on the type of spot model invoked. AG Vir constitutes an excellent example of the expected manifestations of spot activity on a light curve. It also demonstrates the ease with which the spot phenomenon can be invoked to explain the appearance of a light curve and to provide conflicting results. This study shows the necessity of a more thorough investigation of this system using Doppler-imaging techniques and simultaneous infrared and optical photometry.

  19. Ag-bridged Ag2O nanowire network/TiO2 nanotube array p-n heterojunction as a highly efficient and stable visible light photocatalyst.

    PubMed

    Liu, Chengbin; Cao, Chenghao; Luo, Xubiao; Luo, Shenglian

    2015-03-21

    A unique Ag-bridged Ag2O nanowire network/TiO2 nanotube array p-n heterojunction (Ag-Ag2O/TiO2 NT) was fabricated by simple electrochemical method. Ag nanoparticles were firstly electrochemically deposited onto the surface of TiO2 NT and then were partly oxidized to Ag2O nanowires while the rest of Ag mother nanoparticles were located at the junctions of Ag2O nanowire network. The Ag-Ag2O/TiO2 NT heterostructure exhibited strong visible-light response, effective separation of photogenerated carriers, and high adsorption capacity. The integration of Ag-Ag2O self-stability structure and p-n heterojunction permitted high and stable photocatalytic activity of Ag-Ag2O/TiO2 NT heterostructure photocatalyst. Under 140-min visible light irradiation, the photocatalytic removal efficiency of both dye acid orange 7 (AO7) and industrial chemical p-nitrophenol (PNP) over Ag-Ag2O/TiO2 NT reached nearly 100% much higher than 17% for AO7 or 13% for PNP over bare TiO2 NT. After 5 successive cycles under 600-min simulated solar light irradiation, Ag-Ag2O/TiO2 NT remained highly stable photocatalytic activity.

  20. A partial snake for the AGS

    SciTech Connect

    Ratner, L.G.

    1990-01-01

    Based on snake experiments at the Indian University Cyclotron Facility and computer simulations at Brookhaven National Laboratory, as well as the conclusions of a BNL mini-workshop, we feel that a partial Siberian snake is a practical device for the AGS. It is anticipated that such a device could reduce the polarized beam tune-up time from 2--3 weeks to 2--3 days.

  1. New beam instrumentation in the AGS Booster

    SciTech Connect

    Witkover, R.L.

    1991-01-01

    The AGS Booster was designed to accelerate beams from 2{times}10{sup 10} polarized protons to 1.5{times}10{sup 13} protons and heavy ions through Au{sup +33}. The range of beam parameters and the high vacuum, and radiation environment presented challenges for the beam instrumentation. Some interesting beam monitors in the Booster and transport lines, will be described. Where available, results will be presented. 21 refs., 7 figs.

  2. Electrochemical detection of aqueous Ag+ based on Ag+-assisted ligation reaction

    NASA Astrophysics Data System (ADS)

    Miao, Peng; Han, Kun; Wang, Bidou; Luo, Gangyin; Wang, Peng; Chen, Mingli; Tang, Yuguo

    2015-03-01

    In this work, a novel strategy to fabricate a highly sensitive and selective biosensor for the detection of Ag+ is proposed. Two DNA probes are designed and modified on a gold electrode surface by gold-sulfur chemistry and hybridization. In the presence of Ag+, cytosine-Ag+-cytosine composite forms and facilitates the ligation event on the electrode surface, which can block the release of electrochemical signals labeled on one of the two DNA probes during denaturation process. Ag+ can be sensitively detected with the detection limit of 0.1 nM, which is much lower than the toxicity level defined by U.S. Environmental Protection Agency. This biosensor can easily distinguish Ag+ from other interfering ions and the performances in real water samples are also satisfactory. Moreover, the two DNA probes are designed to contain the recognition sequences of a nicking endonuclease, and the ligated DNA can thus be cleaved at the original site. Therefore, the electrode can be regenerated, which allows the biosensor to be reused for additional tests.

  3. Electrochemical detection of aqueous Ag+ based on Ag+-assisted ligation reaction.

    PubMed

    Miao, Peng; Han, Kun; Wang, Bidou; Luo, Gangyin; Wang, Peng; Chen, Mingli; Tang, Yuguo

    2015-03-17

    In this work, a novel strategy to fabricate a highly sensitive and selective biosensor for the detection of Ag(+) is proposed. Two DNA probes are designed and modified on a gold electrode surface by gold-sulfur chemistry and hybridization. In the presence of Ag(+), cytosine-Ag(+)-cytosine composite forms and facilitates the ligation event on the electrode surface, which can block the release of electrochemical signals labeled on one of the two DNA probes during denaturation process. Ag(+) can be sensitively detected with the detection limit of 0.1 nM, which is much lower than the toxicity level defined by U.S. Environmental Protection Agency. This biosensor can easily distinguish Ag(+) from other interfering ions and the performances in real water samples are also satisfactory. Moreover, the two DNA probes are designed to contain the recognition sequences of a nicking endonuclease, and the ligated DNA can thus be cleaved at the original site. Therefore, the electrode can be regenerated, which allows the biosensor to be reused for additional tests.

  4. Plasmon resonances of Ag(001) and Ag(111) studied by power density absorption and photoyield

    NASA Astrophysics Data System (ADS)

    Raseev, Georges

    2013-09-01

    This paper models the surface and bulk plasmon resonances in photoabsorption and photoelectron spectra (PES) of the Ag(001) and the Ag(111) surfaces in the region of 2.8-10 eV excited with a p or transverse magnetic linearly polarized laser incident at 45°. Using the recently developed vector potential from electron density-coupled integro-differential equations (VPED-CIDE, [1,2]) model, we calculate the electron escaping probability from the power density absorption, Feibelman's parameter d⊥, the reflectance and the Fermi PE cross section. In the PES experiment the work function is lowered from 4.5 to 2.8 eV by adsorption of sodium. In our model, this lowering is introduced by adding a phenomenological term to the DFT-LDA model potential of Chulkov et al. [3]. For both Ag(001) and Ag(111), the calculated observables display two plasmon resonances, the multipole surface at 3.70 eV and the bulk at 3.90 eV, in fair agreement with the experimental PES of Barman et al. [4,5] and the reflectance. Except for the Fermi PE cross section of Ag(001) which does not display the multipole surface plasmon resonance at 3.70 eV. This poor result is probably due to a poor calculation of the conduction band wave functions obtained from the Schrödinger equation using the modified DFT-LDA model potential of Chulkov et al.

  5. Isomorphism and solid solutions among Ag- and Au-selenides

    NASA Astrophysics Data System (ADS)

    Palyanova, Galina A.; Seryotkin, Yurii V.; Kokh, Konstantin A.; Bakakin, Vladimir V.

    2016-09-01

    Au-Ag selenides were synthesized by heating stoichiometric mixtures of elementary substances of initial compositions Ag2-xAuxSe with a step of x=0.25 (0≤x≤2) to 1050 °C and annealing at 500 °C. Scanning electron microscopy, optical microscopy, electron microprobe analysis and X-ray powder diffraction methods have been applied to study synthesized samples. Results of studies of synthesized products revealed the existence of three solid solutions with limited isomorphism Ag↔Au: naumannite Ag2Se - Ag1.94Au0.06Se, fischesserite Ag3AuSe2 - Ag3.2Au0.8Se2 and gold selenide AuSe - Au0.94Ag0.06Se. Solid solutions and AgAuSe phases were added to the phase diagram of Ag-Au-Se system. Crystal-chemical interpretation of Ag-Au isomorphism in selenides was made on the basis of structural features of fischesserite, naumannite, and AuSe.

  6. HBcrAg Identifies Patients Failing to Achieve HBeAg Seroconversion Treated with Pegylated Interferon Alfa-2b

    PubMed Central

    Ma, Hui; Yang, Rui-Feng; Li, Xiao-He; Jin, Qian; Wei, Lai

    2016-01-01

    Background: We aimed to evaluate the usefulness of serum hepatitis B virus core-related antigens (HBcrAg) for predicting hepatitis B e antigen (HBeAg) seroconversion in HBeAg-positive chronic hepatitis B patients treated with conventional interferon (IFN) alfa-2b or pegylated IFN. Methods: Fifty-eight patients were enrolled: 29 for the training group and 29 for the validating group. HBcrAg was measured at baseline, week 12, end of the treatment, and 12- and 24-week follow-ups. Sixteen patients in the training group were enrolled in the long-term follow-up (LTFU), during which time the dynamics of the HBcrAg was monitored. Results: The serum HBcrAg level gradually declined during treatment among the HBeAg seroconversion patients of the training group (from baseline, week 12, end of the treatment, 12-week follow-up to 24-week follow-up were 110,245 kU/ml, 3760 kU/ml, 7410 kU/ml, 715 kU/ml, 200 kU/ml, respectively). HBcrAg <19,565 kU/ml at week 24, HBcrAg <34,225 kU/ml at 12-week follow-up, and HBcrAg decrease ≥0.565 log10 kU/ml from the baseline to the end of treatment (EOT) had negative predictive values (NPVs) of 100% for HBeAg seroconversion at the end of follow-up, whereas the positive predictive values (PPVs) were 30.77%, 26.67%, and 25.00%, respectively. The patients with HBeAg seroconversion at the end of 24-week follow-up remained in seroconversion during the LTFU, during which time their serum HBcrAg levels steadily declined or even became undetectable, ranging from 0 to 2.1 kU/ml. Conclusions: Effective antiviral treatment can decrease HBcrAg levels in the serum. The NPVs of HBcrAg for predicting HBeAg seroconversion at 24-week follow-up was 100%, but the PPVs were not satisfactory (all <31%). The serum HBcrAg levels of the patients with HBeAg seroconversion at the end of the 24-week follow-up steadily declined or even became undetectable during the LTFU. PMID:27625094

  7. Heterojunction double dumb-bell Ag2Te-Te-Ag2Te nanowires

    NASA Astrophysics Data System (ADS)

    Som, Anirban; Pradeep, T.

    2012-07-01

    Growth of isolated axial heterojunction nanowires by a solution phase growth process is reported. The dumb-bell shaped nanowires contain two silver telluride sections at the extremes joined by a tellurium section. Reaction of silver nitrate with tellurium NWs in aqueous solution at a molar ratio of 1 : 1 leads to the formation of amorphous partially silver reacted Te NWs. Low temperature (75 °C) solution phase annealing of these silver deficient NWs results in phase segregation producing crystalline Ag2Te and Te phases with clear phase boundaries along the wire axis. Structural characterization of these dumb-bell shaped NWs was performed with different microscopic and spectroscopic tools. Solution phase silver concentration over the course of annealing indicated leaching of silver into the solution during the formation of biphasic NWs. Similar Ag : Te ratios were observed in both partially silver reacted Te NWs and phase segregated Ag2Te-Te-Ag2Te NWs and this was attributed to redeposition of leached silver on the amorphous NW tips which eventually resulted in complete phase segregation. Successful integration of different chemical components in single NWs is expected to open up new application possibilities as physical and chemical properties of the heterostructure can be exploited.Growth of isolated axial heterojunction nanowires by a solution phase growth process is reported. The dumb-bell shaped nanowires contain two silver telluride sections at the extremes joined by a tellurium section. Reaction of silver nitrate with tellurium NWs in aqueous solution at a molar ratio of 1 : 1 leads to the formation of amorphous partially silver reacted Te NWs. Low temperature (75 °C) solution phase annealing of these silver deficient NWs results in phase segregation producing crystalline Ag2Te and Te phases with clear phase boundaries along the wire axis. Structural characterization of these dumb-bell shaped NWs was performed with different microscopic and spectroscopic

  8. SPIN TRANSPORT FROM AGS TO RHIC WTIH TWO PARTIAL SNAKES IN AGS.

    SciTech Connect

    MACKAY, W.W.; LUCCIO, A.U.; TSOUPAS, N.; TAKANO, J.

    2006-06-23

    The stable spin direction in the RHIC rings is vertical. With one or two partial helical Siberian snakes in the AGS, the stable spin direction at extraction is not vertical. Interleaved vertical and horizontal bends in the transport line between AGS and the RHIC rings also tend to tip the spin away from the vertical. In order to maximize polarization in RHIC, we examined several options to improve the matching of the stable spin direction during beam transfer from the AGS to each of the RHIC rings. While the matching is not perfect, the most economical method appears to be a lowering of the injection energy by one unit of G{gamma} from 46.5 to 45.5.

  9. Formation of surface oxides and Ag2O thin films with atomic oxygen on Ag(111)

    NASA Astrophysics Data System (ADS)

    Derouin, Jonathan; Farber, Rachael G.; Heslop, Stacy L.; Killelea, Daniel R.

    2015-11-01

    The nature of the oxygen species adsorbed to silver surfaces is a key component of the heterogeneously catalyzed epoxidation of ethylene and partial oxidation of methanol over silver catalysts. We report the formation of two different silver-oxygen species depending on the flux and energy of incident gas-phase oxygen atoms on an Ag(111) surface. A combination of surface science techniques was used to characterize the oxidized surfaces. Atomic oxygen was generated with an Ir filament; lower temperatures created surface oxides previously reported. When O was deposited with a higher filament temperature, the surface became highly corrugated, little subsurface oxygen was observed, and thin layers of Ag2O were likely formed. These results show that the energy and flux of oxygen are important parameters in the chemical identity and abundance of oxygen on silver surfaces and suggest that formation of the Ag2O thin film hinders formation of subsurface oxygen.

  10. Plasmon-assisted site-selective growth of Ag nanotriangles and Ag-Cu2O hybrids.

    PubMed

    Xie, Ying; Ma, Liang; Cheng, Zi-Qiang; Yang, Da-Jie; Zhou, Li; Hao, Zhong-Hua; Wang, Qu-Quan

    2017-03-21

    We report a plasmon-assisted growth of metal and semiconductor onto the tips of Ag nanotriangles (AgNTs) under light irradiation. The site-selective growth of Ag onto AgNTs are firstly demonstrated on the copper grids and amine-coated glass slides. As the irradiation time increases, microscopic images indicate that AgNTs gradually touch with each other and finally "weld" tip-to-tip together into the branched chains. Meanwhile, the redshift of plasmon band is observed in the extinction spectra, which agrees well the growth at the tips of AgNTs and the decrease of the gaps between the adjacent nanotriangles. We also synthesize AgNT-Cu2O nanocomposites by using a photochemical method and find that the Cu2O nanoparticles preferably grow on the tips of AgNTs. The site-selective growth of Ag and Cu2O is interpreted by the local field concentration at the tips of AgNTs induced by surface plasmon resonance under light excitation.

  11. Plasmon-assisted site-selective growth of Ag nanotriangles and Ag-Cu2O hybrids

    NASA Astrophysics Data System (ADS)

    Xie, Ying; Ma, Liang; Cheng, Zi-Qiang; Yang, Da-Jie; Zhou, Li; Hao, Zhong-Hua; Wang, Qu-Quan

    2017-03-01

    We report a plasmon-assisted growth of metal and semiconductor onto the tips of Ag nanotriangles (AgNTs) under light irradiation. The site-selective growth of Ag onto AgNTs are firstly demonstrated on the copper grids and amine-coated glass slides. As the irradiation time increases, microscopic images indicate that AgNTs gradually touch with each other and finally “weld” tip-to-tip together into the branched chains. Meanwhile, the redshift of plasmon band is observed in the extinction spectra, which agrees well the growth at the tips of AgNTs and the decrease of the gaps between the adjacent nanotriangles. We also synthesize AgNT-Cu2O nanocomposites by using a photochemical method and find that the Cu2O nanoparticles preferably grow on the tips of AgNTs. The site-selective growth of Ag and Cu2O is interpreted by the local field concentration at the tips of AgNTs induced by surface plasmon resonance under light excitation.

  12. Conversion of Ag nanowires to AgCI nanowires decorated with Au nanoparticles and their photocatalytic activity.

    SciTech Connect

    Sun, Y.; Center for Nanoscale Materials

    2010-02-11

    A two-step approach has been developed to synthesize AgCl nanowires decorated with Au nanoparticles by using Ag nanowires as chemical templates. In the first step, the Ag nanowires are oxidized with FeCl{sub 3} followed by a simultaneous precipitation reaction between Ag{sup +} and Cl{sup -} ions at room temperature, resulting in conversion of the Ag nanowires to AgCl nanowires as well as reduction of Fe{sup 3+} to Fe{sup 2+} ions. In the second step, the Fe{sup 2+} ions generated in the first step reduce Au precursors (e.g., NaAuCl{sub 4}) to deposit Au nanoparticles on the surfaces of the AgCl nanowires, resulting in the formation of AgCl:Au composite nanowires. Because of strong surface plasmon resonance and chemical inertness of Au nanoparticles, the as-synthesized AgCl:Au nanowires exhibit enhanced absorption coefficient in the visible region and enhanced chemical stability to prevent them from degradation and aggregation. These unique properties enable the AgCl:Au nanowires to be used as a class of promising plasmonic photocatalysts driven by visible light. Preliminary results demonstrate these composite nanowires can efficiently decompose organics, such as methylene blue molecules, under illumination of white light.

  13. A new HBsAg screening assay designed for sensitive detection of HBsAg subtypes and variants.

    PubMed

    van Roosmalen, M H; de Jong, J J; Haenen, W; Jacobs, T; Couwenberg, F; Ahlers-de Boer, G J C M; Hellings, J A

    2006-01-01

    The design of a new HBsAg screening assay, the Hepanostika HBsAg Ultra is based on the use of monoclonal antibodies raised against native wild-type HBsAg and reactive with HBsAg in which the common 'a'-determinant is modified by site-directed mutagenesis of four of the cysteine moieties. The design was checked using the same cysteine variants and samples from patients known to be infected with HBsAg variants. The results found were compared with other state-of-the-art commercial screening assays. The design of the Hepanostika HBsAg Ultra enabled detection of all variant HBsAg-positive samples in contrast to the other commercial assays. An additional 980 samples were tested to assess the specificity and sensitivity of the Hepanostika HBsAg Ultra. Screening of presumed negative serum and plasma samples resulted in a specificity of 100%. This makes the Hepanostika HBsAg Ultra the first screening assay with a design able to detect HBsAg variants with high sensitivity and specificity.

  14. Plasmon-assisted site-selective growth of Ag nanotriangles and Ag-Cu2O hybrids

    PubMed Central

    Xie, Ying; Ma, Liang; Cheng, Zi-Qiang; Yang, Da-Jie; Zhou, Li; Hao, Zhong-Hua; Wang, Qu-Quan

    2017-01-01

    We report a plasmon-assisted growth of metal and semiconductor onto the tips of Ag nanotriangles (AgNTs) under light irradiation. The site-selective growth of Ag onto AgNTs are firstly demonstrated on the copper grids and amine-coated glass slides. As the irradiation time increases, microscopic images indicate that AgNTs gradually touch with each other and finally “weld” tip-to-tip together into the branched chains. Meanwhile, the redshift of plasmon band is observed in the extinction spectra, which agrees well the growth at the tips of AgNTs and the decrease of the gaps between the adjacent nanotriangles. We also synthesize AgNT-Cu2O nanocomposites by using a photochemical method and find that the Cu2O nanoparticles preferably grow on the tips of AgNTs. The site-selective growth of Ag and Cu2O is interpreted by the local field concentration at the tips of AgNTs induced by surface plasmon resonance under light excitation. PMID:28322264

  15. Highly selective and quantitative colorimetric detection of mercury(II) ions by carrageenan-functionalized Ag/AgCl nanoparticles.

    PubMed

    Narayanan, Kannan Badri; Han, Sung Soo

    2017-03-15

    The natural algal polysaccharide carrageenan was used for the greener synthesis of silver/silver chloride nanoparticles (Carr-Ag/AgCl NPs) without any toxic chemicals. We report the robust, highly selective, and sensitive colorimetric sensing of Hg(2+) ions using Carr-Ag/AgCl NPs without any further surface modification. The dark-brown color of a solution of Carr-Ag/AgCl NPs turned to white in a concentration-dependent manner with the addition of Hg(2+) ions, confirming the interaction of Carr-Ag/AgCl NPs with Hg(2+) ions. The plot of the extinction ratio of absorbance at 350nm to 450nm (A350/A450) for Carr-Ag/AgCl NPs against the concentration of [Hg(2+)] ions was linear, and the calibration curve was A350/A450=1.05254+0.00318×CHg with a lower detection limit of 1μM. This portable and cost-effective method for mercury(II) ion sensing is widely applicable in on-field qualitative and quantitative measurements of [Hg(2+)] ions in environmental or biological samples.

  16. Synthesis of biocompatible AuAgS/Ag2S nanoclusters and their applications in photocatalysis and mercury detection

    NASA Astrophysics Data System (ADS)

    Zhao, Qian; Chen, Shenna; Zhang, Lingyang; Huang, Haowen; Liu, Fengping; Liu, Xuanyong

    2014-12-01

    In this paper, a facile approach for preparation of AuAgS/Ag2S nanoclusters was developed. The unique AuAgS/Ag2S nanoclusters capped with biomolecules exhibit interesting excellent optical and catalytic properties. The fluorescent AuAgS/Ag2S nanoclusters show tunable luminescence depending on the nanocluster size. The apoptosis assay demonstrated that the AuAgS/Ag2S nanoclusters showed low cytotoxicity and good biocompatibility. Therefore, the nanoclusters can be used not only as a probe for labeling cells but also for their photocatalytic activity for photodegradation of organic dye. Moreover, a highly selective and sensitive assay for detection of mercury including Hg2+ and undissociated mercury complexes was developed based on the quenching fluorescent AuAgS/Ag2S nanoclusters, which provides a promising approach for determining various forms of Hg in the mercury-based compounds in environment. These unique nanoclusters may have potential applications in biological labeling, sensing mercury, and photodegradation of various organic pollutants in waste water.

  17. Insights into the adsorption and energy transfer of Ag clusters on the AgCl(100) surface.

    PubMed

    Ma, Xiangchao; Dai, Ying; Guo, Meng; Zhu, Yingtao; Huang, Baibiao

    2013-06-14

    It is fundamental to uncover the real adsorption properties of Ag clusters on an AgCl surface and the energy transfer mechanisms at the interface to understand the highly active photocatalytic performance and the stability of the plasmonic photocatalyst Ag@AgCl. Based on density functional theory calculations we provide valuable insights into the binding nature of Ag clusters on AgCl surface, where the binding between Ag atoms in the cluster and on the surface plays a decisive role in determining the most stable adsorption configurations. Our results demonstrate that there is energy transfer from the plasmonic metals to substrate. The hot holes excited by the decay of surface plasmon resonance on the metals can diffuse into the Cl ions in the outermost two layers of the surface producing highly oxidative Cl atoms. The dipole-dipole interaction between the plasmonic metal clusters and substrate Cl ions can also generate electron-hole pairs in the surface layers. It is deduced that the positively charged nature of adsorbed clusters acting as electron trapping centers and reduction sites plays a crucial role in keeping the stability of the Ag@AgCl system during the photocatalytic process. Finally, the validity of the cluster adsorption model for energy transfer is verified with respect to the nucleation and aggregation process of Ag atoms on the AgCl surface and a detailed description of the formation and evolution of Ag nanoparticles on an AgCl surface is provided. The present study may be helpful for understanding and designing this novel plasmonic photocatalyst and can be useful for investigating other relevant photocatalysts as well.

  18. Ag surface diffusion and out-of-bulk segregation in CrN-Ag nano-composite coatings.

    PubMed

    Incerti, L; Rota, A; Ballestrazzi, A; Gualtieri, E; Valeri, S

    2011-10-01

    CrN-Ag nanocomposite coatings are deposited on Si(100) wafers and 20MnCr5 steel disks in a mixed Ar+N2 atmosphere by reactive magnetron sputtering. Structure, composition and morphology were investigated by Scanning Electron Microscopy (SEM), Auger Electron Spectroscopy (AES), X-ray Photoemission Spectroscopy (XPS), X-ray Diffraction (XRD) and Focused Ion Beam (FIB) cross sectional analysis. The as deposited film matrix is mainly composed by CrN phase (78%), but a relevant part (28%) is composed by Cr2N. Ag agglomerates in the CrN matrix forming elongated grains 200-400 nm wide and 50-100 nm high, which extends on the top of CrN columns. At the surface Ag aggregates into two different structures: large tetrahedral crystalline clusters, with typical dimension ranging from 200 to 500 nm, and smaller Ag nanoparticles with diameter of 15-25 nm. The annealing in N2 atmosphere up to 500 degrees C does not affect size and distribution of the Ag grains in the sub-surface region, while it induces a size increase of the bigger Ag clusters on the surface, mainly related to Ag surface diffusion and clusters coalescence. Annealing at higher temperature leads to an evident Ag out-of-bulk segregation, generating Ag depleted voids in the near-surface region, and further increasing of the Ag clusters size at the surface. Tribological tests on as deposited CrN-Ag film reveal a coefficient of friction against a steel ball reduced with respect to CrN film, probably related to the presence of Ag which acts as solid lubricant, but the coating is removed after a very short sliding distance. The poor mechanical properties of the realized Ag-based coatings are confirmed by lower hardness and Young modulus values with respect to pure CrN.

  19. Fabrication and photoconductivity of macroscopically long coaxial structured Ag/Ag2S nanowires with different core-to-shell thickness ratios.

    PubMed

    Sun, Jia-Lin; Zhu, Jia-Lin; Zhao, Xingchen; Bao, Yang

    2011-01-21

    Macroscopically long core/shell structured Ag/Ag(2)S coaxial nanowires and Ag(2)S nanowires have been fabricated using the solid-state ionics method for Ag nanowires, combined with a subsequent gas-solid reaction, and characterized at different spatial scales. The photoconductive properties of such samples are investigated by performing transport measurements with 532 nm laser illumination ON/OFF cycles under different bias. A significant change in the photoconductivity from negative to positive has been observed in the coaxial structured Ag/Ag(2)S nanowires when the Ag(2)S layer thickness increases to a certain level. Such behaviors are ascribed to two photoconductive mechanisms in the Ag core and the Ag(2)S shell, respectively. These results indicate a promising approach to fabricate nanoscale photoswitches with different dark resistances and photoinduced currents based on the Ag/Ag(2)S coaxial nanowires for various optoelectronic applications.

  20. Fabrication and photoconductivity of macroscopically long coaxial structured Ag/Ag2S nanowires with different core-to-shell thickness ratios

    NASA Astrophysics Data System (ADS)

    Sun, Jia-Lin; Zhu, Jia-Lin; Zhao, Xingchen; Bao, Yang

    2011-01-01

    Macroscopically long core/shell structured Ag/Ag2S coaxial nanowires and Ag2S nanowires have been fabricated using the solid-state ionics method for Ag nanowires, combined with a subsequent gas-solid reaction, and characterized at different spatial scales. The photoconductive properties of such samples are investigated by performing transport measurements with 532 nm laser illumination ON/OFF cycles under different bias. A significant change in the photoconductivity from negative to positive has been observed in the coaxial structured Ag/Ag2S nanowires when the Ag2S layer thickness increases to a certain level. Such behaviors are ascribed to two photoconductive mechanisms in the Ag core and the Ag2S shell, respectively. These results indicate a promising approach to fabricate nanoscale photoswitches with different dark resistances and photoinduced currents based on the Ag/Ag2S coaxial nanowires for various optoelectronic applications.

  1. Double dumbbell shaped AgNi alloy by pulsed electrodeposition

    SciTech Connect

    Dhanapal, K.; Vasumathi, M.; Santhi, Kalavathy; Narayanan, V. Stephen, A.

    2014-01-28

    Silver-Nickel is the well-known thermally immiscible system that makes them quite complex for the formation of alloy. This kind of alloy can be attained from electrodeposition method. In the present work, AgNi alloy was synthesized by pulsed electrodeposition in a single bath two electrode system with the use of anodic alumina membrane. The prepared AgNi alloy and pure Ag were characterized with X-ray Diffraction (XRD) for structural confirmation, Scanning Electron Microscopy (SEM) for morphological, and magnetic properties by Vibrating Sample Magnetometer, respectively. The X-ray Diffraction study shows the formation of cubic structure for pure Ag. SEM analysis reveals the double dumbbell morphology for AgNi alloy and spherically agglomeration for pure silver. Hysteresis behaviour from VSM measurement indicates that the AgNi alloy have good ferro-magnetic properties.

  2. Synthesis and Functions of Ag2S Nanostructures

    NASA Astrophysics Data System (ADS)

    Cui, Chunyan; Li, Xiaoru; Liu, Jixian; Hou, Yongchao; Zhao, Yuqing; Zhong, Guocheng

    2015-11-01

    The paper presents a review about synthesis and applications of Ag2S nanostructures. As the modern photoelectric and biological materials, Ag2S nanomaterials are potentially useful for both structure and function purposes. Ag2S is a direction narrow band gap semiconductor with special properties. Ag2S nanostructures have been widely researched in chemistry and biochemistry fields because of their unusual optical, electrical, and mechanical properties. It can also be used in many fields, such as photovoltaic cells and infrared detector. In the past few years, Ag2S nanostructures have been synthesized by various methods. The article mainly discusses the four types of preparation methods. Moreover, this article shows a detailed review on the new properties, fabrication, and applications of Ag2S nanocrystals.

  3. Oxidative Stress Mechanisms Caused by Ag Nanoparticles (NM300K) are Different from Those of AgNO3: Effects in the Soil Invertebrate Enchytraeus crypticus

    PubMed Central

    Ribeiro, Maria J.; Maria, Vera L.; Scott-Fordsmand, Janeck J.; Amorim, Mónica J. B.

    2015-01-01

    The mechanisms of toxicity of Ag nanoparticles (NPs) are unclear, in particular in the terrestrial environment. In this study the effects of AgNP (AgNM300K) were assessed in terms of oxidative stress in the soil worm Enchytraeus crypticus, using a range of biochemical markers [catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR), total glutathione (TG), metallothionein (MT), lipid peroxidation (LPO)]. E. crypticus were exposed during 3 and 7 days (d) to the reproduction EC20, EC50 and EC80 levels of both AgNP and AgNO3. AgNO3 induced oxidative stress earlier (3 d) than AgNP (7 d), both leading to LPO despite the activation of the anti-redox system. MT increased only for AgNP. The Correspondence Analysis showed a clear separation between AgNO3 and AgNP, with e.g., CAT being the main descriptor for AgNP for 7 d. LPO, GST and GPx were for both 3 and 7 d associated with AgNO3, whereas MT and TG were associated with AgNP. These results may reflect a delay in the effects of AgNP compared to AgNO3 due to the slower release of Ag+ ions from the AgNP, although this does not fully explain the observed differences, i.e., we can conclude that there is a nanoparticle effect. PMID:26287225

  4. Strongly visible-light responsive plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles for reduction of CO2 to methanol.

    PubMed

    An, Changhua; Wang, Jizhuang; Jiang, Wen; Zhang, Meiyu; Ming, Xijuan; Wang, Shutao; Zhang, Qinhui

    2012-09-21

    Plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles have been synthesized by a facile and versatile glycerol-mediated solution route. The as-prepared AgX:Ag nanoparticles exhibit regular shapes, i.e., cube-tetrapod-like AgCl:Ag nanoparticles and AgBr:Ag nanoplates. Compared with the pristine AgX, AgX:Ag nanocomposites display stronger absorption in the visible region due to the surface plasmon resonance of silver nanoparticles. The calculation of bandgaps and band positions indicates the as-achieved AgX:Ag nanoparticles can be used as a class of potential photocatalyst for the reduction of CO(2). For example, reduction of CO(2) under visible light irradiation with the assistance of the anisotropic AgX:Ag nanoparticles yields as much as 100 μmol methanol in the products. Furthermore, the AgX:Ag nanoparticles can maintain its structure and activity after 3 runs of reactions. Therefore, the present route opens an avenue to acquire plasmonic photocatalysts for conversion of CO(2) into useful organic compounds.

  5. Rare and forbidden kaon decays at the AGS

    SciTech Connect

    Kettell, S.

    1997-12-09

    An overview of the Rare Kaon Decay program at the AGS is presented, with particular emphasis on the three major experiments currently running and analyzing data. A brief overview of earlier kaon decay experiments and of the AGs performance improvements is also provided. This review concludes with a discussion of proposed and developing experiments planned to run in the year 2000 and beyond (AGS-2000).

  6. The synthesis, activity, stability and the charge transfer identification of Ag:AgBr/γ-Al2O3 photocatalyst for organic pollutant decomposition in water

    NASA Astrophysics Data System (ADS)

    Huang, Shan; Si, Zhichun; Weng, Duan

    2015-12-01

    Highly stable Ag:AgBr/γ-Al2O3 photo-catalyst was obtained by dispersing AgBr sol on hollow γ-Al2O3 microsphere. Metallic Ag nanoparticles were in situ generated on AgBr crystals by a photo-reduction method. The activity of catalyst was characterized by MO and phenol decomposition. The light irradiation response, the life times of the photo-induced charges, and the charge separation and transition were determined by the UV-vis diffuse reflection spectra, open circuit voltage decay spectra and transient photocurrent responses. The as-prepared Ag:AgBr/γ-Al2O3 catalyst can response to visible light irradiation. Charge separation was clarified to correlate with electrons transferring from Ag to AgBr surface and the consequent reaction with ads-O2 to generate rad O2- species. It was found that the rad O2- rather than rad OH played a dominant role in the photocatalytic oxidation of MO and phenol in water. However, the electrons trended to transfer from AgBr to Ag intrinsically without light irradiation. Therefore, the electron transfer between Ag and AgBr reaching the dynamic equilibrium was the key factor for obtaining a high stable Ag/AgBr catalyst which can be obtained by optimizing the Ag:AgBr ratio. Loading amount of Ag:AgBr on γ-Al2O3 was optimized to 30 wt.% and the metallic Ag content was stabilized at 9 wt.% of Ag:AgBr catalyst.

  7. The development of nontoxic Ag-based brazing alloys

    SciTech Connect

    Timmins, P.F. )

    1994-09-01

    An experimental investigation wad conducted to produce nontoxic, Cd-free brazing alloys that possessed similar melting ranges and mechanical properties to those alloys within the Ag-Cu-Zn-Cd system. The investigation consisted of phase equilibria, Zn equivalence, thermal analysis, extrusion, wire drawing and mechanical testing of alloys based in the Ag-Cu-Zn system. Thermal analysis of these new alloys yielded liquidus temperatures in the range 680 to 775 C (1256--1427 F) and solidus temperatures in the range 625 to 675 C (1157--1247 F). These values compared favorably to the Ag-Cu-Zn-Cd alloys, which have liquidus and solidus temperatures in the ranges of 640 to 710 C (1184--1310 F) and 610 to 620 C (1130--1148 F), respectively, for Ag contents in the 20 to 50 wt-% range. Tensile tests revealed the ultimate tensile strengths of the as-cast Ag-Cu-Zn-Sn alloys to be higher than the toxic Cd-containing alloys of higher Ag content and higher than the ternary Ag-Cu-Zn alloys. For example, the alloy at 35Ag-34Cu-30Zn-1Sn exhibited an as-cast tensile strength of 47.6 kg/mm[sup 2] (67.7 ksi) compared to the alloy at 50Ag-15Cu-16Zn-19Cd with an as-cast tensile strength of 45.7 kg/mm[sup 2] (65 ksi).

  8. AG Pegasi - now a classical symbiotic star in outburst?

    NASA Astrophysics Data System (ADS)

    Tomov, T. V.; Stoyanov, K. A.; Zamanov, R. K.

    2016-11-01

    Optical spectroscopy study of the recent AG Pegasi (AG Peg) outburst observed during the second half of 2015 is presented. Considerable variations of the intensity and the shape of the spectral features as well as the changes of the hot component parameters, caused by the outburst, are discussed and certain similarities between the outburst of AG Peg and the outburst of a classical symbiotic stars are shown. It seems that after the end of the symbiotic nova phase, AG Peg became a member of the classical symbiotic stars group.

  9. Molecular dynamics study of nanojoining between axially positioned Ag nanowires

    NASA Astrophysics Data System (ADS)

    Cui, Jianlei; Theogene, Barayavuga; Wang, Xuewen; Mei, Xuesong; Wang, Wenjun; Wang, Kedian

    2016-08-01

    The miniaturization of electronics devices into nanometer scale is indispensable for next-generation semiconductor technology. Ag nanowires (Ag NWs) are considered to be the promising candidates for future electronic circuit owing to the excellent electrical and thermal properties. The nanojoining of axially positioned Ag NWs was performed by molecular dynamics simulation. Through the detailed atomic evolution during the nanojoining, the results indicate that the temperature and the distance between Ag NWs in axial direction have a great impact on nanojoining effect. When the nanojoining temperature is relatively high, the atoms are disordered and the atomic queues become to distort with strong thermodynamic properties and weak effect of metal bonds. At the relatively low temperature, the Ag NWs can be well connected with good junction quality and their own morphology, which is similar to the cold welding without fusion, while the distance between Ag NWs should be controlled for interaction and diffusion of interfacial atoms at nanowires head. When the Ag NWs are placed on Si and SiO2 substrate, because the atomic species and lattice structure of substrate material can differently affect the motions of Ag atoms through the interactive force between the atoms, the nanojoining quality of Ag NWs on Si substrate is better than that on the SiO2 substrate. So, for getting effective and reliable nanojoining without nanosolders and other materials, the temperature, distance and substrate surface should be reasonably controlled and selected, providing helpful theoretical guidance for experiment and application of nanojoining.

  10. Phytotoxicity of Ag nanoparticles prepared by biogenic and chemical methods

    NASA Astrophysics Data System (ADS)

    Choudhury, Rupasree; Majumder, Manna; Roy, Dijendra Nath; Basumallick, Srijita; Misra, Tarun Kumar

    2016-06-01

    Silver nanoparticles (Ag NPs) are now widely used as antibacterial and antifungal materials in different consumer products. We report here the preparation of Ag NPs by neem leaves extract ( Azadirachta) reduction and trisodium citrate-sodium borohydride reduction methods, and study of their phytotoxicity. The nanoparticles were characterized by UV-Vis spectroscopy, FTIR, and atomic force microscopy (AFM) techniques. Both neem-coated and citrate-coated Ag NPs exhibit surface plasmon around 400 nm, and their average sizes measured by AFM are about 100 and 20 nm, respectively. Antibacterial and antifungal activities of these nanomaterials have been studied by simple pea seed germination and disk diffusion methods. It has been observed from the growth of root and shoot, citrate-coated Ag NPs significantly affect seedling growth, but neem-coated Ag NPs exhibit somehow mild toxicity toward germination process due to the nutrient supplements from neem. On the other hand, antifungal activity of neem-coated Ag NPs has been found much higher than that of citrate-coated Ag NPs due to the combined effects of antifungal activity of neem and Ag NPs. Present research primarily indicates a possible application of neem-coated Ag NPs as a potential fungicide.

  11. RHIC FY15 pp Run RHIC and AGS polarization analysis

    SciTech Connect

    Huang, H.; Adams, P.

    2016-02-20

    The polarization information is important for the spin physics program in Relativistic Heavy Ion Collider (RHIC). There are discrepancies between AGS and RHIC polarization measurements. First, the face value of AGS polarization is higher than RHIC ones in general. Second, the measured polarization profile (described by the profile ratio R) is stronger in AGS than in RHIC. This note analyzes the polarization data from FY15 pp run period. The results show that the differences between AGS and RHIC polarization measurements are reasonable, but the R value difference is puzzling. The difference between blue and yellow ring is worth of spin simulation to explain.

  12. Low temperature sintering of Ag nanoparticles for flexible electronics packaging

    NASA Astrophysics Data System (ADS)

    Hu, A.; Guo, J. Y.; Alarifi, H.; Patane, G.; Zhou, Y.; Compagnini, G.; Xu, C. X.

    2010-10-01

    We achieve robust bonding of Cu wires to Cu pads on polyimide with silver nanopaste cured at 373 K. The paste is prepared by simply condensing Ag nanoparticle (NP) solution via centrifuging. The bonding is formed by solid state sintering of Ag NPs through neck growth and direct metallic bonding between clean Ag-Cu interfaces. Both experiment and Monte Carlo simulation confirm that the melting point of joint clusters increases during sintering. This creates improved bonds for use at an elevated operating temperature using Ag NPs.

  13. Cu-Ag sulfides as indicators of pre-porphyritic epithermal Au-Ag deposits in Northeastern Russia

    NASA Astrophysics Data System (ADS)

    Savva, N. E.; Sidorov, A. A.; Volkov, A. V.

    2016-08-01

    Au-Ag mineralization of the Olcha and Teploe epithermal deposits underwent thermal metamorphism due to porphyritic intrusions. The presence of Bi-bearing galena and matildite in the ores (Teploe), Cu-Te-bearing naumannite (Olcha), the occurrence of middle- and high-temperature facies of metasomatic rocks (epidote and actinolite), and temperature formation conditions are related, firstly, to the influence of granitoids on the ore process, which supplied not only Cu and Mo, but also Bi, Te, and, secondly, to the heating of host rocks containing pre-porphyritic epithermal Au-Ag mineralization. The abundance of Cu-Ag sulfides and Cu-acanthite resulted from the enrichment of later mineral phases in Cu and Ag under the substance redistribution with the formation of Ag-acanthite ores. The data considered in the paper are of practical importance for regional forecasting of metallogenic constructions, exploration, and evaluation of the epithermal Au-Ag deposits.

  14. Mechanical properties of dental Ti-Ag alloys with 22.5, 25, 27.5, and 30 mass% Ag.

    PubMed

    Takahashi, Masatoshi; Kikuchi, Masafumi; Takada, Yukyo

    2015-01-01

    The mechanical properties -tensile strength, yield strength, elongation after fracture, Vickers hardness, and Young's modulus-and the phases of Ti-Ag alloys were investigated, as prepared with 22.5, 25, 27.5, and 30 mass% Ag. The tensile strength, yield strength, hardness, and Young's modulus of the alloys increase with their Ag content up to 25 mass%, but their breaking elongation decreases. These changes in the mechanical properties are attributed to solid-solution strengthening of the α-titanium phase, to Ti2Ag precipitation, and to the formation of eutectic structures composed of α+Ti2Ag. The addition of Ag, at 25 mass% in particular, improves the mechanical properties of these alloys, making them suitable for high strength dental prostheses, such as implantretained superstructures and narrow-diameter implants.

  15. Plasmonic enhancements of photocatalytic activity of Pt/n-Si/Ag photodiodes using Au/Ag core/shell nanorods.

    PubMed

    Qu, Yongquan; Cheng, Rui; Su, Qiao; Duan, Xiangfeng

    2011-10-26

    We report the plasmonic enhancement of the photocatalytic properties of Pt/n-Si/Ag photodiode photocatalysts using Au/Ag core/shell nanorods. We show that Au/Ag core/shell nanorods can be synthesized with tunable plasmon resonance frequencies and then conjugated onto Pt/n-Si/Ag photodiodes using well-defined chemistry. Photocatalytic studies showed that the conjugation with Au/Ag core/shell nanorods can significantly enhance the photocatalytic activity by more than a factor of 3. Spectral dependence studies further revealed that the photocatalytic enhancement is strongly correlated with the plasmonic absorption spectra of the Au/Ag core/shell nanorods, unambiguously demonstrating the plasmonic enhancement effect.

  16. Desorption of Ag from Grain Boundaries in Ag Film on Br and H-Passivated Si(111) Surfaces

    SciTech Connect

    Roy, Anupam; Batabyal, R.; Mahato, J. C.; Dev, B. N.; Sundaravel, B.

    2011-07-15

    Growth of Ag film on Br- and H-passivated Si(111) surfaces was examined by Rutherford backscattering spectrometry (RBS), scanning electron microscopy (SEM) and photoemission electron microscopy (PEEM) techniques. The phenomenon of thermal grooving was observed after annealing at higher temperatures. Hierarchical desorption of Ag from the grain boundaries produce a fractal structure of Ag-depleted regions. Hierarchical desorption may be used for nanopatterning of the layer.

  17. Plasmon-assisted degradation of methylene blue with Ag/AgCl/montmorillonite nanocomposite under visible light.

    PubMed

    Sohrabnezhad, Sh; Zanjanchi, M A; Razavi, M

    2014-09-15

    Metal-semiconductor compounds, such as Ag/AgX (X=Cl, Br, I), enable visible light absorption and separation of photogenerated electron-hole through surface plasmon resonance (SPR) effect. However, the electron-hole generated and separated by light are vulnerable in Ag/AgX phase because of the occurrence of secondary recombined. In order to more effectively utilize the SPR photocatalytic effect, nanoparticles are located in a matrix. In this article, Ag/AgCl nanoparticles were synthesized in montmorillonite (MMT) matrix using dispersion method and light irradiation. The structure, composition and optical properties of such material were investigated by transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray diffraction (XRD) and FTIR. Powder X-ray diffraction showed intercalation of Ag/AgCl nanoparticles into the clay layers. The as-prepared plasmonic photocatalyst exhibited an enhanced and stable photoactivity for the degradation of methylene blue (MB) under visible light. The high activity was attributed to the surface plasmon resonance (SPR) exhibited by Ag nanoparticles on the surface of AgCl. The detection of reactive species by radical scavengers displays that O2- and OH- are the main reactive species for the degradation of MB under visible light irradiation. The studies showed that 20 min illumination under visible light can complete degradation of methylene blue (MB), and indicate a high stability of photocatalytic degradation. The mechanism of separation of the photo-generated electrons and holes at the Ag/AgCl-MMT nanocomposite was discussed.

  18. Component conversion from pure Au nanorods to multiblock Ag-Au-Ag nanorods assisted by Pt nanoframe templates

    NASA Astrophysics Data System (ADS)

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Kim, Seong Kyu; Park, Sungho

    2016-06-01

    We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications.We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03484e

  19. METAL MEDIA FILTERS, AG-1 SECTION FI

    SciTech Connect

    Adamson, D.

    2012-05-23

    One application of metal media filters is in various nuclear air cleaning processes including applications for protecting workers, the public and the environment from hazardous and radioactive particles. To support this application the development of the ASME AG-1 FI Standard on Metal Media has been under way for more than ten years. Development of the proposed section has required resolving several difficult issues associated with operating conditions (media velocity, pressure drop, etc.), qualification testing, and quality acceptance testing. Performance characteristics of metal media are dramatically different than the glass fiber media with respect to parameters like differential pressures, operating temperatures, media strength, etc. These differences make existing data for a glass fiber media inadequate for qualifying a metal media filter for AG-1. In the past much work has been conducted on metal media filters at facilities such as Lawrence Livermore National Laboratory (LLNL) and Savannah River National Laboratory (SRNL) to qualify the media as High Efficiency Particulate Air (HEPA) Filters. Particle retention testing has been conducted at Oak Ridge Filter Test Facility and at Air Techniques International (ATI) to prove that the metal media meets or exceeds the 99.97% particle retention required for a HEPA Filter. Even with his testing, data was lacking to complete an AG-1 FI Standard on metal media. With funding secured by Mississippi State University (MSU) from National Nuclear Security Administration (NNSA), a research test stand is being designed and fabricated at MSU's Institute for Clean Energy Technology (ICET) Facility to obtain qualification data on metal media. This in turn will support required data needed for the FI Standard. The paper will discuss in detail how the test stand at MSU will obtain the necessary data to complete the FI Standard.

  20. Ab initio study of edge smoothing, atom attraction, and downward funneling in Ag/Ag(100)

    NASA Astrophysics Data System (ADS)

    Shim, Yunsic; Amar, Jacques G.

    2011-06-01

    The results of density-functional theory (DFT) calculations of the energy barriers for three low-barrier relaxation processes in Ag/Ag(100) growth—edge-zipping, atom attraction, and downward funneling—are presented and compared with embedded atom method (EAM) calculations. In general, we find good agreement between the DFT values for these processes and the values assumed in recent simulations of low-temperature Ag/Ag(100) growth [Shim and Amar, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.81.045416 81, 045416 (2010)]. We also find reasonable agreement between our DFT results and the results of EAM calculations, although in a few specific cases there is a noticeable disagreement. In order to investigate the effects of long-range interactions, we have also carried out additional calculations for more complex configurations. While our EAM results indicate that long-range interactions such as “pinning” can significantly enhance the energy barriers for edge-zipping and atom attraction, these effects can be significantly weaker in our DFT calculations due to the redistribution of the electron density.

  1. Fabrication of antimicrobial bacterial cellulose-Ag/AgCl nanocomposite using bacteria as versatile biofactory

    NASA Astrophysics Data System (ADS)

    Liu, Chuang; Yang, Dong; Wang, Yuangui; Shi, Jiafu; Jiang, Zhongyi

    2012-08-01

    In nature, a number of nanocomposites are formed through biomineralization-relevant processes under mild conditions. In the present study, a total "biologic" route to fabricate nanocomposite is reported. Non-pathogenic bacteria, Gluconacetobacter xylinum, was utilized as a versatile biofactory, which produced biopolymer bacterial cellulose (BC) and induced the formation of Ag/AgCl nanoparticles, yielding BC-Ag/AgCl nanocomposite. Scanning electron microscopy revealed that nanoparticles with average size of 17.4 nm were randomly embedded into the BC network; transmission electron microscopy and X-ray diffraction confirmed that the nanoparticles were mixtures of face-centered cubic silver and silver chloride nanoparticles. Moreover, the content of silver in the BC nanocomposite is around 0.05 wt%, determined by atomic absorption spectrometry and X-ray photoelectron spectroscopy analysis. The entire process of nanocomposite fabrication was conducted at ambient environment without utilizing toxic agents or producing hazardous products, which is not only environmentally friendly but also with less chances to generate harmful products to human bodies as biomedical materials. The resultant nanocomposite displayed the desirable activity in inhibiting bacterial growth of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms on agar plate and in liquid culture, indicating the potential of the material as antimicrobial wound dressing materials. This work demonstrated the feasibility of using microorganism to fabricate nanocomposite, especially for biomedical materials.

  2. Ag@AgI, core@shell structure in agarose matrix as hybrid: synthesis, characterization, and antimicrobial activity.

    PubMed

    Ghosh, Somnath; Saraswathi, A; Indi, S S; Hoti, S L; Vasan, H N

    2012-06-05

    A novel in situ core@shell structure consisting of nanoparticles of Ag (Ag Nps) and AgI in agarose matrix (Ag@AgI/agarose) has been synthesized as a hybrid, in order to have an efficient antibacterial agent for repetitive usage with no toxicity. The synthesized core@shell structure is very well characterized by XRD, UV-visible, photoluminescence, and TEM. A detailed antibacterial studies including repetitive cycles are carried out on Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria in saline water, both in dark and on exposure to visible light. The hybrid could be recycled for the antibacterial activity and is nontoxic toward human cervical cancer cells (HeLa cells). The water insoluble Ag@AgI in agarose matrix forms a good coating on quartz, having good mechanical strength. EPR and TEM studies are carried out on the Ag@AgI/agarose and the bacteria, respectively, to elucidate a possible mechanism for killing of the bacteria.

  3. Growth and evaluation of AgGaS2 and AgGaSe2 for infrared nonlinear applications

    NASA Technical Reports Server (NTRS)

    Byer, R. L.; Feigelson, R. S.

    1986-01-01

    Significant advances were made in the growth technology of silver thiogallate (AgGaS2) and silver selenogallate (AgGaSe2). High efficiency harmonic generation of carbon dioxide laser radiation and tunable infrared parametric oscillation were demonstrated using these materials. Nonliner frequency conversion in the infrared was limited by the optical properties and the size of the available nonlinear materials. The development of these materials has reduced some of the limitations and generated wide interest. The continued development and application of AgGaS2 and AgGaSe2 now appears assured.

  4. In situ growth of Ag nanoparticles on α-Ag2WO4 under electron irradiation: probing the physical principles

    NASA Astrophysics Data System (ADS)

    San-Miguel, Miguel A.; da Silva, Edison Z.; Zannetti, Sonia M.; Cilense, Mario; Fabbro, Maria T.; Gracia, Lourdes; Andrés, Juan; Longo, Elson

    2016-06-01

    Exploiting the plasmonic behavior of Ag nanoparticles grown on α-Ag2WO4 is a widely employed strategy to produce efficient photocatalysts, ozone sensors, and bactericides. However, a description of the atomic and electronic structure of the semiconductor sites irradiated by electrons is still not available. Such a description is of great importance to understand the mechanisms underlying these physical processes and to improve the design of silver nanoparticles to enhance their activities. Motivated by this, we studied the growth of silver nanoparticles to investigate this novel class of phenomena using both transmission electron microscopy and field emission scanning electron microscopy. A theoretical framework based on density functional theory calculations (DFT), together with experimental analysis and measurements, were developed to examine the changes in the local geometrical and electronic structure of the materials. The physical principles for the formation of Ag nanoparticles on α-Ag2WO4 by electron beam irradiation are described. Quantum mechanical calculations based on DFT show that the (001) of α-Ag2WO4 displays Ag atoms with different coordination numbers. Some of them are able to diffuse out of the surface with a very low energy barrier (less than 0.1 eV), thus, initiating the growth of metallic Ag nanostructures and leaving Ag vacancies in the bulk material. These processes increase the structural disorder of α-Ag2WO4 as well as its electrical resistance as observed in the experimental measurements.

  5. Theoretical modeling of optical properties of Ag8 and Ag14 silver clusters embedded in an LTA sodalite zeolite cavity.

    PubMed

    Cuong, Ngo Tuan; Nguyen, Hue Minh Thi; Nguyen, Minh Tho

    2013-10-07

    Optical properties of silver Ag(n) nanoclusters are demonstrated to be dependent on their size, structure and charge state. It is found that when being contained in the sodalite cavity of LTA zeolite the tetradecanuclear hexacation silver cluster Ag14(6+) is stable. Its lower-lying states and optical spectrum are theoretically determined using the quantum chemical TD-DFT method. Its ground state possesses an outer-shell electron configuration of A1g(2)T2g(6) mimicking the s(2)p(6) valence of noble gas atoms. These frontier orbitals are constructed from 5s,5p(Ag)-AOs with contributions from framework oxygen atoms. Light absorption of Ag14(6+) embedded in the sodalite cage which is characterized by strong peaks centered at 331 and 476 nm (transitions 5s,p(Ag) → 5s,p(Ag)) leads to much longer wavelength emission. The sodalite cage, as a container, stabilizes the central Ag14(6+) cluster by electrostatic attraction. The absorption spectrum of the isovalent neutral Ag8 cluster embedded inside the same sodalite cavity is also simulated using TD-DFT and CASPT2 methods. This absorption spectrum which is similar to that of the Ag14(6+) cluster has two absorption bands in the near UV and visible regions.

  6. Micro-PIXE study of Ag in digestive glands of a nano-Ag fed arthropod ( Porcellio scaber, Isopoda, Crustacea)

    NASA Astrophysics Data System (ADS)

    Tkalec, Živa Pipan; Drobne, Damjana; Vogel-Mikuš, Katarina; Pongrac, Paula; Regvar, Marjana; Štrus, Jasna; Pelicon, Primož; Vavpetič, Primož; Grlj, Nataša; Remškar, Maja

    2011-10-01

    Micro-proton induced X-ray emission (micro-PIXE) method was applied to study the micro-localization of silver (Ag) in digestive glands of a terrestrial arthropod (Porcellio scaber) after feeding on silver nanoparticles (nano-Ag) dosed food. The aim of our work was to assess whether feeding on nano-Ag results in the assimilation of silver (Ag) in digestive gland cells. To study micro-localization and elemental distribution of Ag, the animals were fed on food dosed with nanoparticles for 14 days under controlled laboratory conditions. At the end of the feeding exposure, the animals were dissected and digestive glands prepared for micro-PIXE analyses and TEM investigation. The results obtained by micro-PIXE documented high amounts of Ag inside S-cells of the digestive gland epithelium; however, TEM investigation did not show particle aggregates inside digestive gland cells. Also no adverse effect on feeding behavior was recorded what is a measure of toxic effects. We explain the presence of Ag inside the cells as a result of the assimilation of dissoluted Ag ions from ingested nano-Ag particles. Assimilation of excessive amounts of ingested metal ions in S-cells is a well known metal detoxification mechanism in isopods. We discuss the advantages of using micro-PIXE for the micro-localization of elements in biological tissue in studies of interactions between nanoparticles and biological systems.

  7. Effect of Ag nanoparticles deposition on photocatalytic activity of Ag{sub 2}SO{sub 3}

    SciTech Connect

    Zhang, Xuan Wang, Qi; Hu, Jin-Wen; Zou, Lan-Hua; You, Jia-Wen

    2016-03-15

    Highlights: • Ag{sub 2}SO{sub 3} was developed as novel photocatalyst. • The effect of Ag nanoparticles deposition on photocatalytic activity was investigated. • The activation and deactivation mechanism was proposed. - Abstract: A novel photocatalyst Ag{sub 2}SO{sub 3} was prepared and the effect of Ag nanoparticles, photo-deposited on the surface of Ag{sub 2}SO{sub 3}, on its photocatalytic activity was investigated. The as-prepared photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–vis diffuse reflection spectroscopy (DRS). The photocatalytic activity was evaluated by photo-degradation of rhodamine B dye under UV light irradiation. It was found that the photocatalytic activity of Ag{sub 2}SO{sub 3} was initially enhanced with deposition of Ag nanoparticles, but subsequently declined with Ag nanoparticles overloaded. The possible mechanism was proposed based on experimental results. These findings may contribute to developing novel photocatalysts and understanding of fundamentals of Ag-based photocatalytic materials.

  8. Comparison of antibacterial activities of Ag@TiO2 and Ag@SiO2 core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Dhanalekshmi, K. I.; Meena, K. S.

    2014-07-01

    Core-shell type Ag@TiO2 nanoparticles were prepared by one pot simultaneous reduction of AgNO3 and hydrolysis of Ti (IV) isopropoxide and Ag@SiO2 core-shell nanoparticles were prepared by Stober's method. They were characterized by absorption, XRD, and HR-TEM techniques. XRD patterns show the presence of anatase form of TiO2 and amorphous form of SiO2 and the noble metal (Ag). High resolution transmission electron microscopy measurements revealed that their size is below 50 nm. The antibacterial properties of Ag@TiO2 and Ag@SiO2 core-shell nanoparticles against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were examined by the agar diffusion method. As a result E. coli and S. aureus were shown to be substantially inhibited by Ag@TiO2 and Ag@SiO2 core-shell nanoparticles. These results demonstrated that TiO2 and SiO2 supported on the surface of Ag NPs without aggregation was proved to have enhanced antibacterial activity.

  9. Synthesis and characterization of novel plasmonic Ag/AgX-CNTs (X = Cl, Br, I) nanocomposite photocatalysts and synergetic degradation of organic pollutant under visible light.

    PubMed

    Shi, Huixian; Chen, Jiangyao; Li, Guiying; Nie, Xin; Zhao, Huijun; Wong, Po-Keung; An, Taicheng

    2013-08-14

    A series of novel well-defined Ag/AgX (X = Cl, Br, I) loaded carbon nanotubes (CNTs) composite photocatalysts (Ag/AgX-CNTs) were fabricated for the first time via a facile ultrasonic assistant deposition-precipitation method at the room temperature (25 ± 1 °C). X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption analysis, scanning electron microscopy, and ultraviolet-visible light absorption spectra analysis were used to characterize the structure, morphology, and optical properties of the as-prepared photocatalysts. Results confirmed the existence of the direct interfacial contact between Ag/AgX nanoparticles and CNTs, and Ag/AgX-CNTs nanocomposites exhibit superior absorbance in the visible light (VL) region owing to the surface plasmon resonance (SPR) of Ag nanoparticles. The fabricated composite photocatalysts were employed to remove 2,4,6-tribromophenol (TBP) in aqueous phase. A remarkably enhanced VL photocatalytic degradation efficiency of Ag/AgX-CNTs nanocomposites was observed when compared to that of pure AgX or CNTs. The photocatalytic activity enhancement of Ag/AgX-CNTs was due to the effective electron transfer from photoexcited AgX and plasmon-excited Ag(0) nanoparticles to CNTs. This can effectively decrease the recombination of electron-hole pairs, lead to a prolonged lifetime of the photoholes that promotes the degradation efficiency.

  10. Deflection Missions for Asteroid 2011 AG5

    NASA Technical Reports Server (NTRS)

    Grebow, Daniel; Landau, Damon; Bhaskaran, Shyam; Chodas, Paul; Chesley, Steven; Yeomans, Don; Petropoulos, Anastassios; Sims, Jon

    2012-01-01

    The recently discovered asteroid 2011 AG5 currently has a 1-in-500 chance of impacting Earth in 2040. In this paper, we discuss the potential of future observations of the asteroid and their effects on the asteroid's orbital uncertainty. Various kinetic impactor mission scenarios, relying on both conventional chemical as well as solar-electric propulsion, are presented for deflecting the course of the asteroid safely away from Earth. The times for the missions range from pre-keyhole passage (pre-2023), and up to five years prior to the 2040 Earth close approach. We also include a brief discussion on terminal guidance, and contingency options for mission planning.

  11. Analysis of the symbiotic star AG Pegasi

    NASA Technical Reports Server (NTRS)

    Keyes, C. D.; Plavec, M. J.

    1981-01-01

    High and low dispersion IUE data are analyzed in conjunction with coincident ground based spectrophotometric scans and supplementary infrared photometry of the symbiotic object AG Pegasi. The IUE observations yield an improved value of E(B-V) = 0.12. The two stellar components are easily recognized in the spectra. The cool component may be an M1.7 III star and the hot component appears to have T (sub eff) of approximately 30000 K. The emission lines observed in the ultraviolet indicate two or three distince emitting regions. Nebular component ultraviolet intercombination lines suggest an electron density of several times 10 billion/cu cm.

  12. Modelling of the AGS using Zgoubi - Status

    SciTech Connect

    Meot F.; Ahrens, L.; Dutheil, Y.; Glenn, J.; Huang, H.; Roser, T.; Schoefer, V.; Tsoupas, N.

    2012-05-20

    This paper summarizes the progress achieved so far, and discusses various outcomes, regarding the development of a model of the Alternating Gradient Synchrotron at the RHIC collider. The model, based on stepwise ray-tracing methods, includes beam and polarization dynamics. This is an on-going work, and a follow-on of code developments and particle and spin dynamics simulations that have been subject to earlier publications at IPAC and PAC [1, 2, 3]. A companion paper [4] gives additional informations, regarding the use of the measured magnetic field maps of the AGS main magnets.

  13. Fluorescence switch for silver ion detection utilizing dimerization of DNA-Ag nanoclusters.

    PubMed

    Lee, Jihyun; Park, Juhee; Hee Lee, Hong; Park, Hansoo; Kim, Hugh I; Kim, Won Jong

    2015-06-15

    A fluorescence switch that consists of DNA-templated silver nanoclusters (DNA-AgNCs) triggered by silver ion (Ag(+)) is developed to detect Ag(+). The mechanism of the fluorescence switching of DNA-AgNCs is investigated by fluorescence spectroscopy, circular dichroism spectroscopy, DNA hybridization assay and mass spectrometry. Ag(+) induces a dimeric structure of Cyt12-AgNCs by forming a bridge between two Cyt12-AgNCs, where Cyt12 is cytosine 12-mer; this dimer formation causes the fluorescence change of Cyt12-AgNCs from red to green. Using this Ag(+)-triggered fluorescence switch, we successfully detected Ag(+) at concentrations as low as 10nM. Furthermore, we quantitatively detected the Ag(+) in the Silmazin(®), which is dermatological burn ointment having silver sulfadiazine. Ag(+) detection using this fluorescence switch has high selectivity and sensitivity, and short response time, and can be used successfully even in the presence of other metal ions.

  14. Structural Characterization of the Ag/ybco Interface

    NASA Astrophysics Data System (ADS)

    Tidjani, Mohammed Elkhamis

    1990-01-01

    The present research is intended to characterize the interface microstructure and long term stability of the deposited silver metal in contact to the superconducting oxide YBa_2Cu_3O _{rm 7-x} (YBCO). High resolution transmission electron microscopy (HRTEM) observations of the interfacial regions reveal that Ag contacts to YBCO occurred without any intermediate phase formation at the interface. The Ag metal exhibits a preferred orientation relationship with YBCO, in which the densely packed planes and directions of the metal are parallel to those of the superconductor. The formation of (111) interfaces and facets during deposition indicates that these planes are associated with the lowest interfacial energy. The as-deposited Ag film exhibits a granular morphology, and the Ag grains are often twinned along the (111) plane while the surface of YBCO is mostly rough and structurally unstable. Annealing of the Ag/YBCO interface resulted in outdiffusion of yttrium and oxygen at regions where the surface of YBCO was rough. This diffusion, however, did not result in the formation of continuous layers at the Ag/YBCO interface but only to growth of Ag_2 Y and Ag_2O inclusions. Thus it is believed that the stability of the Ag/YBCO depends on the quality of the surface of YBCO, especially its structure. Treatment of the surface of YBCO by ion-bombardment yielded flat surfaces but damaged a layer of about 30A. Such a cleaning process improved the quality of the deposited Ag since the Ag grains were larger and contained low defects concentration. The same orientation relationships between Ag and YBCO were observed after cleaning the surface of YBCO which implied that the destruction of the structure at the surface is only partial. Deposition of Ag in the same chamber where YBCO was initially grown, to minimize the contamination of the surface of YBCO, also was not effective in enhancing the structure of the Ag/YBCO interface. The roughness of the surface of YBCO did not decrease

  15. The role of reduction extent of graphene oxide in the photocatalytic performance of Ag/AgX (X = Cl, Br)/rGO composites and the pseudo-second-order kinetics reaction nature of the Ag/AgBr system.

    PubMed

    Gao, Weiyin; Ran, Chenxin; Wang, Minqiang; Li, Le; Sun, Zhongwang; Yao, Xi

    2016-07-21

    Although reduced graphene oxide (rGO)-based photocatalyst composites have been intensively developed during the past few years, the influence of reduction extent of rGO on the photocatalytic performance of the rGO-based composite has virtually not been investigated due to some technical limitations, such as the poor water dispersibility of rGO and low reduction selectivity of the hydrothermal method, which make it difficult to control the reduction extent of rGO in these composites. Herein, we used a facile room-temperature method to synthesize Ag/AgX (X = Cl, Br)/rGO photocatalyst composites as a model to study the effect of reduction extent of rGO on the photocatalytic performance of the photocatalyst. It was found that the photocatalytic activities of both Ag/AgCl/PrGO and Ag/AgBr/PrGO systems had an optimized threshold of the reduction extent of photoreduced GO (PrGO). More importantly, due to the different conductive band values of AgCl and AgBr, the optimized thresholds in the two systems were at different PrGO reduction extents, based on which we proposed that the favorable energy band matching between AgX and PrGO in the two systems played a crucial role in obtaining high photocatalysis performance. Besides, the photocatalytic reaction of the Ag/AgBr based system was confirmed to be a pseudo-second-order kinetics reaction rather than pseudo-first-order kinetics reaction. The new insights presented in this work provided useful information on the design and development of a more sophisticated photocatalyst, and can also be applied to many other applications.

  16. Ag/AgBr/g-C{sub 3}N{sub 4}: A highly efficient and stable composite photocatalyst for degradation of organic contaminants under visible light

    SciTech Connect

    Cao, Jing; Zhao, Yijie; Lin, Haili; Xu, Benyan; Chen, Shifu

    2013-10-15

    Graphical abstract: Ag/AgBr/g-C{sub 3}N{sub 4} composite photocatalysts displayed excellent photocatalytic activities on the degradation of methyl orange (MO) under visible light. The improved photocatalytic performance and stability of Ag/AgBr/g-C{sub 3}N{sub 4} originated from the synergetic effects of AgBr/g-C{sub 3}N{sub 4} interface and metallic Ag nanoparticles. ·O{sub 2}−, one of the reactive species, was responsible for the photodegradation of MO compared to H+ and ·OH. - Highlights: • Novel Ag/AgBr/g-C{sub 3}N{sub 4} composite photocatalyst was reported. • Ag/AgBr/g-C{sub 3}N{sub 4} had novel energy band combination between AgBr and g-C{sub 3}N{sub 4}. • Synergetic effects of AgBr/g-C{sub 3}N{sub 4} interface and metallic Ag nanoparticles. • Electron trapping role of metallic Ag dominated the stability of Ag/AgBr/g-C{sub 3}N{sub 4}. - Abstract: Novel Ag/AgBr/g-C{sub 3}N{sub 4} composite photocatalysts were constructed via deposition–precipitation method and extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and UV–vis diffuse reflectance spectroscopy (DRS). Under visible light (λ > 420 nm), Ag/AgBr/g-C{sub 3}N{sub 4} composite photocatalysts displayed much higher photocatalytic activities than those of Ag/AgBr and g-C{sub 3}N{sub 4} for degradation of methyl orange (MO). 50% Ag/AgBr/g-C{sub 3}N{sub 4} presented the best photocatalytic performance, which was mainly attributed to the synergistic effects of AgBr/g-C{sub 3}N{sub 4} interface and the in situ metallic Ag nanoparticles for efficiently separating electron–hole pairs. Furthermore, Ag/AgBr/g-C{sub 3}N{sub 4} remained good photocatalytic activity through 5 times of cycle experiments. Additionally, the radical scavengers experiment indicated that ·O{sub 2}{sup −} was the main reactive species for the MO degradation under visible light.

  17. Molecular structure of (AgPO3)1-x (AgI)x glasses

    NASA Astrophysics Data System (ADS)

    Novita, D.

    2005-03-01

    Melt-quenched AgPO3 glasses were synthesized by dry ( Ag3PO4 + P2O5, prep. 1) and wet (NH4H2PO4 + AgNO3, prep. 2) routes. Glass transitions were examined in MDSC at a scan rate of 3^oC/min. Prep. 1 samples display bimodal glass transition temperatures, with Tg^low = 220^oC and Tg^high = 238^oC and with the Tg^low endotherm higher in strength than the Tg^high one. In contrast, prep. 2 samples show a single Tg = 203^oC that is significantly lower in temperature. These results are consistent with the notion that prep. 2 probably yields samples with bonded water while prep 1 gives pure AgPO3 glasses that are intrinsically phase separated. The nature of the two phases in the latter is less obvious at present, but we note that upon alloying AgI, the additive selectively bonds in the Tg^low phase at low x (<0.20) with Tg^low steadily decreasing, and with the Tg^high phase remaining largely unaffected. At higher x (>0.20) a major structural reorganization occurs, and we observe the opening of a reversibility window in the 0.22 < x < 0.37 range. As in the chalcogenides, we identify the window with the intermediate phase with glasses at x < 0.20 stressed-rigid, while those at x > 0.37 as floppy. A percolation threshold for electrical conduction occurs^1 near x ˜ 0.3 and falls in the reversibility window as expected. 1. M. Mangion and G.P. Johari, Phys. Rev. B36, 8845 (1987) Supported by NSF grant DMR 04-56472

  18. RRR and thermal conductivity of Ag and Ag0.2wt%Mg alloy in Ag/Bi-2212 wires

    SciTech Connect

    Li, Pei; Ye, L.; Jiang. J., Jiang. J.; Shen, T.

    2015-08-19

    The residual resistivity ratio (RRR) and thermal conductivity of metal matrix in metal/superconductor composite wires are important parameters for designing superconducting magnets. However, the resistivity of silver in reacted Ag/Bi-2212 wires has yet to be determined over temperature range from 4.2 K to 80 K because Bi-2212 filaments have a critical transition temperature Tc of ~ 80 K, and because it is unknown whether the RRR of Ag/Bi-2212 degrades with Cu diffusing from Bi-2212 filaments into silver sheathes at elevated temperatures and to what degree it varies with heat treatment. We measured the resistivity of stand-alone Ag and AgMg (Ag-0.2wt%Mg) wires as well as the resistivity of Ag and Ag- 0.2wt%Mg in the state-of-the-art Ag/Bi-2212 round wires reacted in 1 bar oxygen at 890 °C for 1, 8, 24 and 48 hours and quickly cooled to room temperature. The heat treatment was designed to reduce the critical current Ic of Bi-2212 wires to nearly zero while allowing Cu loss to fully manifest itself. We determined that pure silver exhibits a RRR of ~ 220 while the oxide-dispersion strengthened AgMg exhibits a RRR of ~ 5 in stand-alone samples. A surprising result is that the RRR of silver in the composite round wires doesn’t degrade with extended time at 890 °C for up to 48 hours. This surprising result may be explained by our observation that the Cu that diffuses into the silver tends to form Cu2O precipitates in oxidizing atmosphere, instead of forming Ag-Cu solution alloy. We also measured the thermal conductivity and the magneto-resistivity of pure Ag and Ag-0.2 wt%Mg from 4.2 K to 300 K in magnetic fields up to 14.8 T and summarized them using a Kohler plot.

  19. Microwave-assisted solvothermal synthesis of flower-like Ag/AgBr/BiOBr microspheres and their high efficient photocatalytic degradation for p-nitrophenol

    SciTech Connect

    Li, Tingting; Luo, Shenglian; Yang, Lixia

    2013-10-15

    Flower-like Ag/AgBr/BiOBr microspheres were successfully fabricated by the approach of microwave-assisted solvothermal and in situ photo-assisted reduction. A reactive ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C{sub 16}mim]Br) was employed as Br source in the presence of surfactant polyvinylpyrrolidone (PVP). The photocatalytic activity of Ag/AgBr/BiOBr towards the decomposition of p-nitrophenol under visible light irradiation was evaluated. The results indicated that Ag/AgBr/BiOBr showed enhanced photocatalytic activity towards p-nitrophenol, comparing with P25, BiOBr and Ag/AgBr. More than 96% of p-nitrophenol was decomposed in 3.5 h under visible-light irradation. The excellent photocatalytic activity of flower-like Ag/AgBr/BiOBr microspheres can be attributed to the large specific surface area, strong visible-light absorption, suitable energy band structure and surface plasmon resonance effect of Ag nanoparticles. The possible photocatalytic mechanism was proposed based on the active species test and band gap structure analysis. - Graphical abstract: The photocatalytic reaction mechanisms of the as-prepared Ag/AgBr/BiOBr. Display Omitted - Highlights: • Successful synthesis of flower-like Ag/AgBr/BiOBr microspheres. • The Ag/AgBr/BiOBr showed much higher photocatalytic activity towards p-nitrophenol as compared to BiOBr and Ag/AgBr. • The reasons for the excellent photocatalytic activity are the large specific surface area, strong visible-light absorption and surface plasmon resonance effect of Ag nanoparticles. • The O{sub 2}·{sup −}, Br{sup 0} and photogenerated h{sup +} play key roles in the photocatalytic degradation process.

  20. Increased intensity performance of the Brookhaven AGS

    SciTech Connect

    Raka, E.; Ahrens, L.; Frey, W.; Gill, E.; Glenn, J.W.; Sanders, R.; Weng, W.

    1985-05-01

    With the advent of H/sup -/ injection into the Brookhaven AGS, circulating beams of up to 3 x 10/sup 13/ protons at 200 MeV have been obtained. Rf capture of 2.2 x 10/sup 13/ and acceleration of 1.73 x 10/sup 13/ up to the transition energy (approx. = 8 GeV) and 1.64 x 10/sup 13/ to full energy (approx. = 29 GeV) has been achieved. This represents a 50% increase over the best performance obtained with H/sup +/ injection. The increase in circulation beam current is obtained without filling the horizontal aperture. This allows the rf capture process to utilize a larger longitudinal phase space area (approx. = 1 eV sec/bunch vs less than or equal to 0.6 eV sec with H/sup +/ operation). The resulting reduction in relative longitudinal density partially offsets the increase in space charge effects at higher currents. In order to make the capture process independent of injected beam current, a dynamic beam loading compensation loop was installed on the AGS rf system. This is the only addition to the synchrotron itself that was required to reach the new intensity records. A discussion of injection, the rf capture process, and space charge effects is presented. 9 refs., 5 figs.

  1. Thermal Diffusion Dynamic Behavior of Two-Dimensional Ag-SMALL Clusters on Ag(1 1 1) Surface

    NASA Astrophysics Data System (ADS)

    Zakirur-Rehman; Hayat, Sardar Sikandar

    2015-07-01

    In this paper, the thermal diffusion behavior of small two-dimensional Ag-islands on Ag(1 1 1) surface has been explored using molecular dynamics (MD) simulations. The approach is based on semi-empirical potentials. The key microscopic processes responsible for the diffusion of Ag1-5 adislands on Ag(1 1 1) surface are identified. The hopping and zigzag concerted motion along with rotation are observed for Ag one-atom to three-atom islands while single-atom and multi-atom processes are revealed for Ag four-atom and five-atom islands, during the diffusion on Ag(1 1 1) surface. The same increasing/decreasing trend in the diffusion coefficient and effective energy barrier is observed in both the self learning kinetic Monte Carlo (SLKMC) and MD calculations, for the temperature range of 300-700 K. An increase in the value of effective energy barrier is noticed with corresponding increase in the number of atoms in Ag-adislands. A reasonable linear fit is observed for the diffusion coefficient for studied temperatures (300, 500 and 700 K). For the observed diffusion mechanisms, our findings are in good agreement with ab initio density-functional theory (DFT) calculations for Al/Al(1 1 1) while the energy barrier values are in same range as the experimental values for Cu/Ag(1 1 1) and the theoretical values using ab initio DFT supplemented with embedded-atom method for Ag/Ag(1 1 1).

  2. Quantification of HBsAg: basic virology for clinical practice.

    PubMed

    Lee, Jung Min; Ahn, Sang Hoon

    2011-01-21

    Hepatitis B surface antigen (HBsAg) is produced and secreted through a complex mechanism that is still not fully understood. In clinical fields, HBsAg has long served as a qualitative diagnostic marker for hepatitis B virus infection. Notably, advances have been made in the development of quantitative HBsAg assays, which have allowed viral replication monitoring, and there is an opportunity to make maximal use of quantitative HBsAg to elucidate its role in clinical fields. Yet, it needs to be underscored that a further understanding of HBsAg, not only from clinical point of view but also from a virologic point of view, would enable us to deepen our insights, so that we could more widely expand and apply its utility. It is also important to be familiar with HBsAg variants and their clinical consequences in terms of immune escape mutants, issues resulting from overlap with corresponding mutation in the P gene, and detection problems for the HBsAg variants. In this article, we review current concepts and issues on the quantification of HBsAg titers with respect to their biologic nature, method principles, and clinically relevant topics.

  3. AGS vertical beta function measurements for Run 15

    SciTech Connect

    Harper, C.; Ahrens, L.; Huang, H.; Schoefer, V.

    2016-10-07

    One key parameter for running the AGS efficiently is by maintaining a low emittance. To measure emittance, one needs to measure the beta function throughout the cycle. This can be done by measuring the beta function at the ionization profile monitors (IPM) in the AGS. This tech note delves into the motivation, the measurement, and some strides that were made throughout Run15.

  4. EMU Ag-Zn battery wet-life extension test

    NASA Astrophysics Data System (ADS)

    Bragg, Bobby J.; Wooten, Claude M.

    1992-02-01

    The Extravehicular Mobility Unit (EMU) silver/zinc (Ag/Zn) battery is an 11 cell battery of approximately 30 AH. The Ag/Zn battery is comprised of two 4-cell monoblocks and one 3-cell monoblock. A discussion of a wet-life extension test performed on the battery is given in viewgraph form.

  5. Transport of engineered silver (Ag) nanoparticles through partially fractured sandstones

    NASA Astrophysics Data System (ADS)

    Neukum, Christoph; Braun, Anika; Azzam, Rafig

    2014-08-01

    Transport behavior and fate of engineered silver nanoparticles (AgNP) in the subsurface is of major interest concerning soil and groundwater protection in order to avoid groundwater contamination of vital resources. Sandstone aquifers are important groundwater resources which are frequently used for public water supply in many regions of the world. The objective of this study is to get a better understanding of AgNP transport behavior in partially fractured sandstones. We executed AgNP transport studies on partially fissured sandstone drilling cores in laboratory experiments. The AgNP concentration and AgNP size in the effluent were analyzed using flow field-flow fractionation mainly. We employed inverse mathematical models on the measured AgNP breakthrough curves to identify and quantify relevant transport processes. Physicochemical filtration, time-dependent blocking due to filling of favorable attachment sites and colloid-facilitated transport were identified as the major processes for AgNP mobility. Physicochemical filtration was found to depend on solute chemistry, mineralogy, pore size distribution and probably on physical and chemical heterogeneity. Compared to AgNP transport in undisturbed sandstone matrix reported in the literature, their mobility in partially fissured sandstone is enhanced probably due to larger void spaces and higher hydraulic conductivity.

  6. HBsAg sT123N mutation induces stronger antibody responses to HBsAg and HBcAg and accelerates in vivo HBsAg clearance.

    PubMed

    Li, Songxia; Zhao, Kaitao; Liu, Shuhui; Wu, Chunchen; Yao, Yongxuan; Cao, Liang; Hu, Xue; Zhou, Yuan; Wang, Yun; Pei, Rongjuan; Lu, Mengji; Chen, Xinwen

    2015-12-02

    Immune escape mutants with mutations in the hepatitis B surface antigen (HBsAg) major hydrophilic region (MHR) often emerge in association with diagnostic failure or breakthrough of HBV infection in patients with anti-HBs antibodies. Some mutants harboring substitutions to Asn in HBsAg MHR may have an additional potential N-glycosylation site. We have previously showed that sT123N substitution could generate additional N-glycosylated forms of HBsAg. In the present study, 1.3-fold-overlength HBV genomes containing the sT123N substitution were digested from the pHBV1.3-sT123N construct and subcloned into the pAAV vector to generate pAAV1.3-sT123N for hydrodynamic injection (HI) in mice. Viral expression and replication were phenotypically characterized by transient transfection. The results demonstrated that sT123N substitution impaired virion secretion, resulting in intracellular retention of HBcAg. Using the HBV HI mouse model, we found that mice mounted significantly stronger antibody responses to HBsAg and HBcAg, which accelerated HBsAg clearance. Thus, additional N-glycosylation generated by amino acid substitutions in HBsAg MHR may significantly modulate specific host immune responses and influence HBV infection in vivo. Our results help further the understanding of the role of immune escape mutants with N-linked glycosylation in the biology of HBV infection.

  7. EMU Ag-Zn battery wet-life extension test

    NASA Technical Reports Server (NTRS)

    Bragg, Bobby J.; Wooten, Claude M.

    1992-01-01

    The Extravehicular Mobility Unit (EMU) silver/zinc (Ag/Zn) battery is an 11 cell battery of approximately 30 AH. The Ag/Zn battery is comprised of two 4-cell monoblocks and one 3-cell monoblock. A discussion of a wet-life extension test performed on the battery is given in viewgraph form.

  8. Fabrication of graphene oxide enwrapped Z-scheme Ag2SO3/AgBr nanoparticles with enhanced visible-light photocatalysis

    NASA Astrophysics Data System (ADS)

    Wan, Yujuan; Liang, Chunyan; Xia, Yue; Huang, Wei; Li, Zelin

    2017-02-01

    A novel graphene oxide (GO) enwrapped Ag2SO3/AgBr (GO/Ag2SO3/AgBr) composite was fabricated through a facile solution approach via electrostatic interaction and precipitation transformation reaction for the first time. The results of XRD, Raman, SEM, TEM and XPS confirmed the structure, morphology and composition of the GO/Ag2SO3/AgBr composite very well. The Ag2SO3/AgBr nanoparticles were found to be encapsulated by GO sheets. The photocatalytic activity of the composite was investigated by the degradation of methyl orange (MO), rhodamine B (RhB) and methylene blue (MB) in water under visible light. The incorporation of GO sheets not only significantly enhanced the photocatalytic activity but also improved the reusability of Ag2SO3/AgBr nanoparticles. The photocatalytic ability of GO/Ag2SO3/AgBr can be maintained at a high level for 4 times cycle experiments. The trapping experiments confirmed that holes and superoxide ion radicals were the main active species responsible for the degradation reaction. A plasmonic Z-scheme photocatalytic mechanism was proposed to illustrate the possible transferred and separated behavior of electron-hole pairs among Ag, Ag2SO3, AgBr and GO quaternary system under visible light irradiation.

  9. Embedment of nano-sized Ag layer into Ag-doped In2O3 films for use as highly transparent and conductive anode in organic solar cells

    NASA Astrophysics Data System (ADS)

    Cho, Da-Young; Na, Seok-In; Chung, Kwun-Bum; Kim, Han-Ki

    2015-08-01

    By inserting a nano-sized Ag layer between bottom Ag-doped In2O3 (AIO) and a top AIO layer, we were able to control the sheet resistance and optical transmittance of AIO films for application in organic solar cells (OSCs) as a transparent electrode. To optimize the AIO/Ag/AIO multilayer, we investigated the electrical, optical, structural and morphological properties of the AIO/Ag/AIO multilayer as a function of Ag interlayer thickness with a constant bottom and top AIO thickness of 35 nm. The optimized AIO/Ag/AIO multilayer showed a much lower resistivity of 3.988 × 10-5 Ω cm and a higher optical transmittance of 84.79% than the values (4.625 × 10-4 Ω cm and 78.36%) of the single AIO film, due to the high conductivity of the metallic Ag layer and the antireflection effect of the symmetric AIO/Ag/AIO structure. In addition, we investigated the performances of OSCs with AIO/Ag/AIO electrodes as a function of Ag interlayer thickness to determine the optimal Ag thickness to produce a high power conversion efficiency (PCE) of the OSCs. Based on the PCE of the OSCs, we correlated the performance of the OSCs with the Ag interlayer thickness in the AIO/Ag/AIO multilayer and suggested a possible mechanism to explain the dependency of PCE on Ag thickness in AIO/Ag/AIO multilayer electrodes.

  10. A Simple Method for the Preparation of TiO2 /Ag-AgCl@Polypyrrole Composite and Its Enhanced Visible-Light Photocatalytic Activity.

    PubMed

    Yao, Tongjie; Shi, Lei; Wang, Hao; Wang, Fangxiao; Wu, Jie; Zhang, Xiao; Sun, Jianmin; Cui, Tieyu

    2016-01-01

    A novel and facile method was developed to prepare a visible-light driven TiO2 /Ag-AgCl@polypyrrole (PPy) photocatalyst with Ag-AgCl nanoparticles supported on TiO2 nanofibers and covered by a thin PPy shell. During the synthesis, the PPy shell and Ag-AgCl nanoparticles were prepared simultaneously onto TiO2 nanofibers, which simplified the preparation procedure. In addition, because Ag-AgCl aggregates were fabricated via partly etching the Ag nanoparticles, their size was well controlled at the nanoscale, which was beneficial for improvement of the contact surface area. Compared with reference photocatalysts, the TiO2 /Ag-AgCl@PPy composite exhibited an enhanced photodegradation activity towards rhodamine B under visible-light irradiation. The superior photocatalytic property originated from synergistic effects between TiO2 nanofibers, Ag-AgCl nanoparticles and the PPy shell. Furthermore, the TiO2 /Ag-AgCl@PPy composite could be easily separated and recycled without obvious reduction in activity.

  11. Surface-enhanced Raman spectroscopy for DNA detection by the self-assembly of Ag nanoparticles onto Ag nanoparticle-graphene oxide nanocomposites.

    PubMed

    Lin, Tsung-Wu; Wu, Hong-Yi; Tasi, Ting-Ti; Lai, Ying-Huang; Shen, Hsin-Hui

    2015-07-28

    A novel surface-enhanced Raman scattering (SERS) sensing system which operates by the self-assembly of Ag nanoparticles (AgNPs) onto the nanocomposite of AgNPs and graphene oxide (AgNP-GO) in the presence of two complementary DNAs has been developed. In this system, AgNP-GO serves as a SERS-active substrate. The AgNPs with the modification of non-fluorescent 4-mercaptobenzoic acid (4-MBA) act as highly efficient Raman probes for DNA hybridization. When probe DNAs on AgNP-GO are complementary to target DNAs on AgNPs functionalized with 4-MBA, the DNA hybridization occurring directs the self-assembly of AgNPs onto AgNP-GO, leading to the creation of SERS hot spots. Due to the fact that partial 4-MBA molecules are located in the region of the hot spots, their SERS signals are greatly enhanced, indicating successful DNA hybridization. It is noteworthy that the size of AgNPs contributes significantly to the enhancement of SERS activity. The detection limit of the target DNAs at the pM level can be achieved through the self-assembly of large sized AgNPs onto AgNP-GO. More importantly, the AgNP-AgNP-GO system shows reproducible SERS signals in proportion to the logarithm of the target DNA concentrations spanning from 10(-6) to 10(-12) M and the excellent capability for multiplex DNA detection.

  12. Ferromagnetic resonance of ultrathin Co /Ag superlattices on Si(111)

    NASA Astrophysics Data System (ADS)

    Kakazei, G. N.; Martin, P. P.; Ruiz, A.; Varela, M.; Alonso, M.; Paz, E.; Palomares, F. J.; Cebollada, F.; Rubinger, R. M.; Carmo, M. C.; Sobolev, N. A.

    2008-04-01

    Ferromagnetic resonance (FMR) is used to probe the magnetic properties of Co /Ag superlattices (SLs) with ultrathin Co layers (2-6Å). Different series of 5×[Ag/Co] multilayers have been grown by molecular beam epitaxy on Si(111) substrates, monitoring the growth by reflection high energy electron diffraction. Cross-section transmission electron microscopy confirms the growth of local areas with the designed SL periodicity, a sharp compositional modulation, well defined Ag-Co interfaces, and a perfect fcc (111) stacking. FMR spectra have been recorded at various polar angles in the 0°-90° range. A single and extremely broad resonance peak is observed in all cases. While SLs with Ag layers thinner than 10Å exhibit similar values of the perpendicular anisotropy, a clear reduction is observed for samples with Ag layers about 14Å thick. Possible causes for this change are discussed.

  13. Luminescence sensitization of Tb(3+)-DNA complexes by Ag().

    PubMed

    Xu, Lijun; Zhou, Lu; Chen, Xing; Shen, Xiaoqiang; Wang, Jine; Zhang, Jianye; Pei, Renjun

    2017-03-03

    Terbium ions (Tb(3+)) with unique photophysical properties have been utilized to develop biosensors with low background and high sensitivity. In this study, the Ag(+)-sensitized luminescence of Tb(3+)-DNA complexes was uncovered. The luminescence of Tb(3+)-DNA complexes could be enhanced by more than 30 times in the presence of Ag(+), when Tb(3+) was bound with poly(G) and poly(T) whereas not with other homopolymers. This research confirmed that the sensitization resulted from the interaction of Ag(+) with certain bases involved in DNA, not just with the reported certain G-quadruplex sequence. The coordination of Ag(+) to guanine and thymine bases was expected to increase their rigidities, form Tb(3+)-DNA-Ag(+) ternary structures, and thus enhance energy transfer from guanine and thymine to Tb(3+). These findings benefit the development of sensitive luminescence probes for various nucleic acids-related targets.

  14. MULTIPLE SINGLE BUNCH EXTRACTION TO THE AGS SWITCHYARD.

    SciTech Connect

    BROWN,K.A.; AHRENS,L.; GASSNER,D.; GLENN,J.W.; ROSER,T.; SMITH,G.; TSOUPAS,N.; VAN ASSELT,W.; ZENO,K.

    2001-06-18

    In this report we will describe the multiple single bunch extraction system as utilized to deliver beams to the Brookhaven's Alternating Gradient Synchrotron (AGS) switchyard area. We will describe modifications of the AGS switchyard, necessary to allow it to accept bunched beam, and results of the first commissioning of this system. The AGS Switchyard has for many years been used to simultaneously deliver (unbunched) resonant extracted beam to a set of fixed target experiments. In order to accommodate new fixed target experiments which require bunched beams, a method of sending the bunched beams to the AGS Switchyard was required. In addition, by using the AGS switchyard instead of the upstream section of the Brookhaven's Relativistic Heavy Ion Collider (RHIC) injection line the accelerators can be reconfigured quickly and efficiently for filling RHIC. We will present results of the commissioning of this system, which was done in January 2001.

  15. Spin relaxation characteristics in Ag nanowire covered with various oxides

    NASA Astrophysics Data System (ADS)

    Karube, S.; Idzuchi, H.; Kondou, K.; Fukuma, Y.; Otani, Y.

    2015-09-01

    We have studied spin relaxation characteristics in a Ag nanowire covered with various oxide layers of Bi2O3, Al2O3, HfO2, MgO, or AgOx by using non-local spin valve structures. The spin-flip probability, a ratio of momentum relaxation time to spin relaxation time at 10 K, exhibits a gradual increase with an atomic number of the oxide constituent elements, Mg, Al, Ag, and Hf. Surprisingly, the Bi2O3 capping was found to increase the probability by an order of magnitude compared with other oxide layers. This finding suggests the presence of an additional spin relaxation mechanism such as Rashba effect at the Ag/Bi2O3 interface, which cannot be explained by the simple Elliott-Yafet mechanism via phonon, impurity, and surface scatterings. The Ag/Bi2O3 interface may provide functionality as a spin to charge interconversion layer.

  16. Asymmetry-induced resistive switching in Ag-Ag2S-Ag memristors enabling a simplified atomic-scale memory design

    NASA Astrophysics Data System (ADS)

    Gubicza, Agnes; Manrique, Dávid Zs.; Pósa, László; Lambert, Colin J.; Mihály, György; Csontos, Miklós; Halbritter, András

    2016-08-01

    Prevailing models of resistive switching arising from electrochemical formation of conducting filaments across solid state ionic conductors commonly attribute the observed polarity of the voltage-biased switching to the sequence of the active and inert electrodes confining the resistive switching memory cell. Here we demonstrate stable switching behaviour in metallic Ag-Ag2S-Ag nanojunctions at room temperature exhibiting similar characteristics. Our experimental results and numerical simulations reveal that the polarity of the switchings is solely determined by the geometrical asymmetry of the electrode surfaces. By the lithographical design of a proof of principle device we demonstrate the merits of simplified fabrication of atomic-scale, robust planar Ag2S memory cells.

  17. Asymmetry-induced resistive switching in Ag-Ag2S-Ag memristors enabling a simplified atomic-scale memory design

    PubMed Central

    Gubicza, Agnes; Manrique, Dávid Zs.; Pósa, László; Lambert, Colin J.; Mihály, György; Csontos, Miklós; Halbritter, András

    2016-01-01

    Prevailing models of resistive switching arising from electrochemical formation of conducting filaments across solid state ionic conductors commonly attribute the observed polarity of the voltage-biased switching to the sequence of the active and inert electrodes confining the resistive switching memory cell. Here we demonstrate stable switching behaviour in metallic Ag-Ag2S-Ag nanojunctions at room temperature exhibiting similar characteristics. Our experimental results and numerical simulations reveal that the polarity of the switchings is solely determined by the geometrical asymmetry of the electrode surfaces. By the lithographical design of a proof of principle device we demonstrate the merits of simplified fabrication of atomic-scale, robust planar Ag2S memory cells. PMID:27488426

  18. MO degradation by Ag-Ag2O/g-C3N4 composites under visible-light irradation.

    PubMed

    Wang, Xin; Yan, Jia; Ji, Haiyan; Chen, Zhigang; Xu, Yuanguo; Huang, Liying; Zhang, Qi; Song, Yanhua; Xu, Hui; Li, Huaming

    2016-01-01

    The paper demonstrated the synthesis of Ag-Ag2O/g-C3N4 nanoparticles via a simple liquid phase synthesis path and a facile calcination method. The synthesized Ag-Ag2O/g-C3N4 composites were well characterized by various analytical techniques, such as X-ray diffraction, Fourier transform infrared (FT-IR), X-ray photoemission spectroscopy, transmission electron microscopy, scanning electron microscopy, high resolution transmission electron microscopy, the UV-Vis diffuse-reflectance spectra and transient photocurrent. From the structure and surface characterization, it indicated that Ag-Ag2O/g-C3N4 composites were formed by an effective covering of g-C3N4 with Ag-Ag2O. The results revealed that the 50 wt% nanoparticle had a great effection on the degradation of the methyl orange (MO), which was almost 7.5 times as high as that of g-C3N4. Based on the experimental results, the possible photocatalytic mechanism with photogenerated holes as the main active species was presented.

  19. Discrete and Polymeric, Mono- and Dinuclear Silver Complexes of a Macrocyclic Tetraoxime Ligand with AgI–AgI Interactions

    PubMed Central

    Tashiro, Shohei; Tanihira, Jun-ichiro; Yamada, Mihoko; Shionoya, Mitsuhiko

    2013-01-01

    Macrocyclic compounds that can bind cationic species efficiently and selectively with their cyclic cavities have great potential as excellent chemosensors for metal ions. Recently, we have developed a tetraoxime-type tetraazamacrocyclic ligand 1 formed through a facile one-pot cyclization reaction. Aiming to explore and bring out the potential of the tetraoxime macrocycle 1 as a chelating sensor, we report herein the preparation of several kinds of silver complexes of 1 and their unique coordination structures determined by single-crystal X-ray diffraction analyses. As a result, the formation of two kinds of discrete structures, monomeric complexes [Ag(1)X] (X = counter anions) and a dimeric complex [Ag2(1)2]X2, and two kinds of polymeric structures from a mononuclear complex, [Ag(1)]nXn, and from a dinuclear complex, [Ag2(1)X2]n, was demonstrated. In the resulting complexes, the structurally flexible macrocyclic ligand 1 was found to provide several different coordination modes. Notably, in some silver complexes of 1, AgI–AgI interactions were observed with different AgI–AgI distances which depend on the kind of counter anions and the chemical composition. PMID:23645105

  20. Recyclable and visible light sensitive Ag-AgBr/TiO2: Surface adsorption and photodegradation of MO

    NASA Astrophysics Data System (ADS)

    Liu, Xinxin; Zhang, Dong; Guo, Biao; Qu, Yue; Tian, Ge; Yue, Huijuan; Feng, Shouhua

    2015-10-01

    A range of highly efficient nanoheterojunction structured Ag-AgBr/TiO2 photocatalysts have been synthesized by CTAB-assisted method and characterized by X-ray diffraction (XRD), focused ion beam scanning electron microscopy (FIB-SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL). The results demonstrated that Ag-AgBr nanoparticles were successfully deposited on the surface of anatase TiO2 hierarchical spheres. The remarkable adsorptive removal of methyl orange (MO) by the uncalcined samples was investigated before evaluating its photocatalytic ability. All the calcined three-component catalysts possessed excellent photocatalytic activities for degrading MO under visible light, in which, 162.4% Ag-AgBr/TiO2 exhibited highest efficiency. The greatly enhanced activity can be attributed to the well combination of surface plasmons photocatalyst Ag-AgBr and TiO2, which can simultaneously inhibit the photo-generated electrons and holes recombination. The nanoheterojunctions architecture catalyst also showed high stability even after five consecutive cycles. Meanwhile, the possible mechanism and interpretation of the photocatalytic process were also proposed.

  1. Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers prepared by atmospheric plasma treatment and electrospinning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers were prepared by atmospheric plasma treatment and electrospinning. Atmospheric helium plasma treatment was first used to reduce the silver nitrate precursor in pre-electrospinning solutions into metallic silver nanoparticles, foll...

  2. Transmission enhancement of THz pulse through Ag2O-Ag layer detected by THz-TDS

    NASA Astrophysics Data System (ADS)

    Chen, Hua; Li, Wang

    2008-12-01

    We used terahertz time-domain spectroscopy (THz-TDS) to probe the enhancement transmission of Ag2O-Ag compound. Using a 500μm- GaAs substrate attaching to the sample, the evanescent wave is coupled to the far field. And the transmitted amplitude is enhanced, corresponding to the frequent shift and spectra broadening.

  3. 78 FR 13931 - Designation of Iyad ag Ghali, Also Known as Iyad ag Ghaly, as a Specially Designated Global...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Designation of Iyad ag Ghali, Also Known as Iyad ag Ghaly, as a Specially Designated Global Terrorist Pursuant to Section 1(b) of Executive Order 13224, as Amended Acting under the authority of and in accordance with section 1(b) of Executive Order 13224...

  4. Construction of Ag/AgCl Reference Electrode from Used Felt-Tipped Pen Barrel for Undergraduate Laboratory

    ERIC Educational Resources Information Center

    Inamdar, Shaukatali N.; Bhat, Mohsin A.; Haram, Santosh K.

    2009-01-01

    A reference electrode is one of the prerequisites of electrochemical investigations. Many electrodes are commercially available but are expensive and prone to accidental breakage by students. Here we report a simple, easy-to-fabricate, inexpensive, reliable, unbreakable, and reproducible Ag/AgCl reference electrode. The empty barrel of a…

  5. Screening different Brassica spp. germplasm for resistance to Rhizoctonia solani AG-2-1 and AG-8

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poor stands of canola seedlings in Pacific Northwest (PNW) have been associated with Rhizoctonia solani AG-2-1 and AG-8. A total of eighty five genotypes of Brassica napus, B. rapa, B. carinata, B. juncea and Sinapsis alba were evaluated in the growth chamber for their resistance to both R. solani A...

  6. Nano Ag@AgBr surface-sensitized Bi2WO6 photocatalyst: oil-in-water synthesis and enhanced photocatalytic degradation

    NASA Astrophysics Data System (ADS)

    Lin, Shuanglong; Liu, Li; Hu, Jinshan; Liang, Yinghua; Cui, Wenquan

    2015-01-01

    Nano Ag@AgBr decorated on the surface of flower-like Bi2WO6 (hereafter designated Ag@AgBr/Bi2WO6) were prepared via a facile oil-in-water self-assembly method. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), etc. The characterization results indicated that nano Ag@AgBr was observed to be evenly dispersed on the surface of Bi2WO6, and was approximately 20 nm in size. Ag@AgBr/Bi2WO6 composites exhibited excellent UV-vis absorption, due to quantum dimension effect of Ag@AgBr, the surface plasmonic resonance (SPR) of Ag nanoparticles and the special flower-like structure of Bi2WO6. The photoelectrochemical measurement verified that the suitable band potential of Ag@AgBr and Bi2WO6 and the existence of metal Ag resulted in the high efficiency in charge separation of the composite. The photocatalytic activities of the Ag@AgBr/Bi2WO6 samples were examined under visible-light irradiation for the degradation of methylene blue (MB). The composite presented excellent photocatalytic activity due to the synergetic effect of Bi2WO6, AgBr, and Ag nanoparticles. The Ag@AgBr(20 wt.%)/Bi2WO6 sample exhibited the best photocatalytic activity, degrading 95.03% MB after irradiation for 2 h, which was respectively 1.29 times and 1.28 times higher than that of Ag@AgBr and Bi2WO6 photocatalyst. Meanwhile, phenol and salicylic acid were degraded to further prove the degradation ability of Ag@AgBr/Bi2WO6. Additionally, studies performed using radical scavengers indicated that O2-•, •OH and Br0 acted as the main reactive species. Based on above, a photocatalytic mechanism for organics degradation over Ag@AgBr/Bi2WO6 was proposed.

  7. Synthesis and photocatalytic performance of an efficient Ag@AgBr/K{sub 2}Ti{sub 4}O{sub 9} composite photocatalyst under visible light

    SciTech Connect

    Liang, Yinghua; Lin, Shuanglong; Liu, Li; Hu, Jinshan; Cui, Wenquan

    2014-08-15

    Highlights: • The plasmatic Ag@AgBr sensitized K{sub 2}Ti{sub 4}O{sub 9} composite photocatalysts. • Ag@AgBr greatly increased visible light absorption for K{sub 2}Ti{sub 4}O{sub 9}. • The plamonic photocatalysts exhibited enhanced activity for the degradation of RhB. - Abstract: Ag@AgBr nanoparticle-sensitized K{sub 2}Ti{sub 4}O{sub 9} composite photocatalysts (Ag@AgBr/K{sub 2}Ti{sub 4}O{sub 9}) were prepared by a facile precipitation–photoreduction method. The photocatalytic activities of the Ag@AgBr/K{sub 2}Ti{sub 4}O{sub 9} nanocomposites were evaluated for photocatalytic degradation of (RhB) under visible light irradiation. The composites exhibited excellent visible light absorption, which was attributable to the surface plasmon effect of Ag nanoparticles. The Ag@AgBr was uniformly scattered on the surface of K{sub 2}Ti{sub 4}O{sub 9} and possessed sizes in the range of 20–50 nm. The loading amount of Ag@AgBr was also studied, and was found to influence the absorption spectra of the resulting composites. Approximately 95.9% of RhB was degraded by Ag@AgBr (20 wt.%)/K{sub 2}Ti{sub 4}O{sub 9} after irradiation for 1 h. The stability of the material was also investigated by performing consecutive runs. Additionally, studies performed using radical scavengers indicated that ·O{sub 2}{sup −} and Br{sup 0} acted as the main reactive species. Based on the experimental results, a photocatalytic mechanism for organics degradation over Ag@AgBr/K{sub 2}Ti{sub 4}O{sub 9} photocatalysts was proposed.

  8. Fabrication and characterization of extended arrays of Ag{sub 2}S/Ag nanodot resistive switches

    SciTech Connect

    Wang Daoai; Liu Lifeng; Kim, Yunseok; Pantel, Daniel; Hesse, Dietrich; Alexe, Marin; Huang Zhipeng

    2011-06-13

    Well-ordered Ag{sub 2}S/Ag nanodot arrays with a density of >60 Gbit/in.{sup 2} have been fabricated by sputtering Ag on a silicon substrate using ultrathin porous anodic aluminum oxide membranes as shadow masks, followed by sulfurization treatment at room temperature. The morphology, microstructure, and electrical properties of the as-prepared nanodots were characterized by scanning electron microscopy, x-ray diffractometry, transmission electron microscopy, and conductive atomic force microscopy, respectively. Well-defined resistive switching behavior was observed in these nanodots, and the ON/OFF ratio was found to be higher than 10{sup 2}. The Ag{sub 2}S/Ag nanodot arrays hold substantial promise for use as ultrahigh density nonvolatile memory devices.

  9. The Antimicrobial Properties of Silver Nanoparticles in Bacillus subtilis Are Mediated by Released Ag+ Ions

    PubMed Central

    Hsueh, Yi-Huang; Lin, Kuen-Song; Ke, Wan-Ju; Hsieh, Chien-Te; Chiang, Chao-Lung; Tzou, Dong-Ying; Liu, Shih-Tung

    2015-01-01

    The superior antimicrobial properties of silver nanoparticles (Ag NPs) are well-documented, but the exact mechanisms underlying Ag-NP microbial toxicity remain the subject of intense debate. Here, we show that Ag-NP concentrations as low as 10 ppm exert significant toxicity against Bacillus subtilis, a beneficial bacterium ubiquitous in the soil. Growth arrest and chromosomal DNA degradation were observed, and flow cytometric quantification of propidium iodide (PI) staining also revealed that Ag-NP concentrations of 25 ppm and above increased membrane permeability. RedoxSensor content analysis and Phag-GFP expression analysis further indicated that reductase activity and cytosolic protein expression decreased in B. subtilis cells treated with 10–50 ppm of Ag NPs. We conducted X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses to directly clarify the valence and fine structure of Ag atoms in B. subtilis cells placed in contact with Ag NPs. The results confirmed the Ag species in Ag NP-treated B. subtilis cells as Ag2O, indicating that Ag-NP toxicity is likely mediated by released Ag+ ions from Ag NPs, which penetrate bacterial cells and are subsequently oxidized intracellularly to Ag2O. These findings provide conclusive evidence for the role of Ag+ ions in Ag-NP microbial toxicity, and suggest that the impact of inappropriately disposed Ag NPs to soil and water ecosystems may warrant further investigation. PMID:26669836

  10. Rotational spectrum of the AgS radical in the X2Πi state

    NASA Astrophysics Data System (ADS)

    Okabayashi, Toshiaki; Oya, Atsushi; Yamamoto, Takuya; Mizuguchi, Den-ichiro; Tanimoto, Mitsutoshi

    2016-11-01

    The rotational spectrum of the AgS radical in the X2Πi state was observed using a source-modulation microwave spectrometer. This radical was generated in a free-space cell by a DC glow discharge under Ar-diluted H2S. Silver atoms were supplied by sputtering from silver sheets placed on the inner surface of the stainless steel cathode. Rotational transitions from J = 7.5 - 6.5 to 39.5 - 38.5 were measured in the 58-310 GHz region. Rotational, centrifugal distortion, and several fine- and hyperfine-structure constants were determined by least-squares analysis. Other spectroscopic parameters such as the dissociation energy, vibrational wavenumber, and equilibrium bond length were also derived from the determined molecular constants. In addition, some electronic properties were estimated from the fine- and hyperfine-structure constants.

  11. Optical absorption spectra and structures of Ag{6/+} and Ag{8/+}

    NASA Astrophysics Data System (ADS)

    Shayeghi, A.; Götz, D. A.; Johnston, R. L.; Schäfer, R.

    2015-06-01

    This work presents optical photodissociation spectra of the Ag{6/+} and the Ag{8/+} clusters in the photon energy range ħω = 1.9-4.4 eV. Experimental spectra are interpreted by means of range separated TDDFT using the LC- ωPBEh and HSE06 functionals, where putative global minimum structures are obtained by the new pool-based Birmingham Cluster Genetic Algorithm, coupled with density functional theory. Structural assignment is facilitated by additionally taking data from previous ion mobility experiments into account. Both functionals reproduce the measured spectra very well, whereas HSE06 shows an almost quantitative agreement, questioning the importance of Hartree-Fock exchange in the long-range part of the range separated functional.

  12. In situ scanning tunneling microscopy investigation of sulfur oxidative underpotential deposition on Ag(100) and Ag(110).

    PubMed

    Lastraioli, E; Loglio, F; Cavallini, M; Simeone, F C; Innocenti, M; Carlà, F; Foresti, M L

    2010-11-16

    Underpotential (UPD) deposition of sulfur from Na(2)S solution in 0.1 M NaOH was studied on Ag(100) and Ag(110) using in situ scanning tunneling microscopy (STM). The cyclic voltammogram on Ag(100) presents two broad peaks, whereas three partial overlapping peaks and a sharper one are observed on Ag(110). STM measurements carried out during the whole UPD process show that progressively more compact structures are formed as the applied potential is scanned toward more positive potentials. More precisely, p(2×2), c(2×6), and c(2×2) were found on Ag(100) at E = -1.25, -1.0, and -0.9 V, respectively. Less definite conclusions can be drawn for the structures of S overlayers on Ag(110). However, the experimental findings are consistent with an incomplete p(2×1) at potentials preceding the sharp peak, and with a c(2×2) structure at E = -0.9 V vs Ag/AgCl, KCl(sat). The coverage values calculated on the basis of the hypothesized structures have been compared with the values obtained from chronocoulometric measurements at the most positive potentials investigated. Thus, the experimental coverage θ = 0.5 coincides with the coverage calculated for the c(2×2) structure found on Ag(110) at E = -0.9 V by STM, whereas the experimental coverage θ = 0.42 suggests that a mixture of structures c(2×6) and c(2×2) is formed on Ag(100).

  13. Thermoelectric Generators from AgBiTe and AgSbTe Thin Films Modified by High-Energy Beam

    NASA Astrophysics Data System (ADS)

    Budak, S.; Guner, S.; Muntele, C.; Ila, D.

    2015-06-01

    The ternary chalcogenides AgBiTe2 and AgSbTe2 belong to the family of semiconductors with disordered NaCl cubic structure in which Ag and Sb occupy metal sublattices. Both compounds are very interesting due to their thermoelectric properties. We have grown single-layer AgBiTe and AgSbTe thin films on silicon (Si) and fused silica (Suprasil) substrates using electron beam deposition. High-energy (MeV) Si-ion bombardment was performed on the thin-film samples at five different fluences between 5 × 1013 ions/cm2 and 7 × 1015 ions/cm2. We have measured the thermoelectric efficiency (figure of merit, ZT) of the fabricated thermoelectric devices by measuring the cross-plane thermal conductivity using the third-harmonic (3 ω) method, the cross-plane Seebeck coefficient, and the in-plane electrical conductivity using the van der Pauw method before and after MeV Si-ion bombardment. Rutherford backscattering spectrometry and the Rutherford Universal Manipulation Program (RUMP) simulation package were used to analyze the elemental composition and thickness of the deposited materials on the substrates. The RUMP simulation gave thicknesses for the AgBiTe and AgSbTe thin films of 270 nm and 188 nm, respectively. The figure of merit for AgBiTe started to decrease from the value of 0.37 for the virgin sample after bombardment. We saw similar decreasing behavior for the AgSbTe thin-film system. The figure of merit for AgSbTe started to decrease from the value of 0.88 for the virgin sample after bombardment. MeV Si-ion bombardment caused changes in the thermoelectric properties of the thin films.

  14. Incoherent Ag islands growth on Ni(100)

    NASA Astrophysics Data System (ADS)

    Marie, J. B.; Braems, I.; Bellec, A.; Chacon, C.; Creuze, J.; Girard, Y.; Gueddani, S.; Lagoute, J.; Repain, V.; Rousset, S.

    2017-02-01

    Growth of two-dimensional superstructure and island morphologies of silver atoms evaporated on a nickel (100) surface are studied by scanning tunneling microscopy. Near-equilibrium islands form at moderate annealing temperature (lower than 500 K) and present two kinds of morphologies. While they share a common monolayer c(2×8) superstructure, two distinct populations of islands coexist: rounded islands grown on the surface and spindle-shaped islands grown inside the Ni surface. The latter present a clear saturation of their density with increasing coverage. These shapes are mostly dominated by boundary energies as confirmed by a simple two-dimensional Wulff model whose parameters are derived using molecular statics simulations. Further annealing to 700 K leads to long Ag strips decorating the Ni step edges.

  15. Ag-Composites with Antimicrobial Properties

    NASA Astrophysics Data System (ADS)

    Zampino, D.; Ferreri, T.; Puglisi, C.; Mancuso, M.; Zaccone, R.; Scaffaro, R.

    2008-08-01

    Polymer composites with antimicrobial properties were prepared by mixing plasticised poly(vinyl chloride) (PVC) pellets with silver nanoparticles and silver zeolite in the amount of 8 wt% and 10 wt%, respectively. Thermal and mechanical properties of PVC composites were obtained by tensile and calorimetric (TGA and DSC) measurements. Rheological characterization was also performed by a parallel plates rheometer. The results indicate that the thermal and mechanical properties of PVC composites were not affected by the presence of both silver additives, with respect to the pure plasticised PVC. The antibacterial activity of PVC composites was examined on Escherichia coli and Staphylococcus epidermidis in Trypticase Soy Broth and in Trypticase Soy Agar for the direct inhibition. PVC composite with Ag-zeolite exhibited antibacterial activity against S. epidermidis and E. coli in culture broth and direct inhibition in agar plate (inhibition zone: 2-4 mm), for more than 7 days. PVC composites containing silver nanoparticles showed very low antimicrobial activity.

  16. Mobil AG scores with massive frac

    SciTech Connect

    Bleakley, W.B.

    1984-01-01

    Mobil Oil AG, West Germany, added 20 bcf of natural gas to the field reserves and improved well productivity five-fold through a massive fracture of the Mainsand section of the Upper Rotliegendes formation in Soehlingen field. The frac job was the largest ever in Europe and is felt to be the world's largest in terms of sintered bauxite used. The fracture treatment also showed that it is possible to put 9,000 lb/min of bauxite into a hydraulically formed fracture. This is believed to be a record rate for this high-strength proppant. Mobil engineers feel, however, that Ottawa sand could probably be used, and they may try it if another opportunity presents itself.

  17. Surface spin polarization induced ferromagnetic Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Shih, Po-Hsun; Li, Wen-Hsien; Wu, Sheng Yun

    2016-05-01

    We report on the observation of ferromagnetic spin polarized moments in 4.5 nm Ag nanoparticles. Both ferromagnetic and diamagnetic responses to an applied magnetic field were detected. The spin polarized moments shown under non-linear thermoinduced magnetization appeared on the surface atoms, rather than on all the atoms in particles. The saturation magnetization departed substantially from the Bloch T3/2-law, showing the existence of magnetic anisotropy. The Heisenberg ferromagnetic spin wave model for Ha-aligned moments was then employed to identify the magnetic anisotropic energy gap of ~0.12 meV. Our results may be understood by assuming the surface magnetism model, in which the surface atoms give rise to polarized moments while the core atoms produce diamagnetic responses.

  18. Synthesis of AG@AgCl Core-Shell Structure Nanowires and Its Photocatalytic Oxidation of Arsenic (III) Under Visible Light.

    PubMed

    Qin, Yanyan; Cui, Yanping; Tian, Zhen; Wu, Yangling; Li, Yilian

    2017-12-01

    Ag@AgCl core-shell nanowires were synthesized by oxidation of Ag nanowires with moderate FeCl3, which exhibited excellent photocatalytic activity for As(III) oxidation under visible light. It was proved that the photocatalytic oxidation efficiency was significantly dependent on the mole ratio of Ag:AgCl. The oxidation rate of As(III) over Ag@AgCl core-shell nanowires first increased with the decrease of Ag(0) percentage, up until the optimized synthesis mole ratio of Ag nanowires:FeCl3 was 2.32:2.20, with 0.023 mg L(-1) min(-1) As(III) oxidation rate; subsequently, the oxidation rate dropped with the further decrease of Ag(0) percentage. Effects of the pH, ionic strength, and concentration of humic acid on Ag@AgCl photocatalytic ability were also studied. Trapping experiments using radical scavengers confirmed that h(+) and ·O2(-) acted as the main active species during the visible-light-driven photocatalytic process for As(III) oxidation. The recycling experiments validated that Ag@AgCl core-shell nanowires were a kind of efficient and stable photocatalyst for As(III) oxidation under visible-light irradiation.

  19. The A2Σ+-XΠi electronic transition of AgS

    NASA Astrophysics Data System (ADS)

    Gupta, Varun; Mazzotti, Fabio J.; Rice, Corey A.; Nagarajan, Ramya; Maier, John P.

    2013-04-01

    The near-infrared electronic transition of silver monosulfide, AgS was measured for the first time using mass-resolved 1+1' resonance enhanced ionization spectroscopy in the 10 000-11 000 cm-1 region. The observed vibronic bands were analysed to obtain ωe″=331.6(2) cm and ωexe″=1.3(1) cm for the ground state, and Te=10528.3(2) cm, ωe'=318.4(1) cm, ωexe'=1.4(1) cm for the excited state of 107Ag32 S. The transitions are assigned to the A2Σ+-X2Πi system based on the rotational analysis of the Ω″=3/2 spin-orbit component of the 0-0 and 1-0 vibronic bands. The rotational constants for the X2Π state were determined to be B″=0.13126(16) cm , D″=5.5(17)×10-7 cmand A″=-477(8) cm .

  20. β decay of neutron-rich 118Ag and 120Ag isotopes

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Rinta-Antila, S.; Dendooven, P.; Huikari, J.; Jokinen, A.; Kolhinen, V. S.; Lhersonneau, G.; Nieminen, A.; Nummela, S.; Penttilä, H.; Peräjärvi, K.; Szerypo, J.; Wang, J. C.; Äystö, J.

    2003-06-01

    β decays of on-line mass-separated neutron-rich 118Ag and 120Ag isotopes have been studied by using β-γ and γ-γ coincidence spectroscopy. Extended decay schemes to the 118,120Cd daughter nuclei have been constructed. The three-phonon quintuplet in 118Cd is completed by including a new level at 2023.0 keV, which is tentatively assigned the spin and parity of 2+4. The intruder band in 118Cd is proposed up to the 4+ level at 2322.4 keV. The measured β-decay half-life for the high-spin isomer of 120Ag is 0.40±0.03 s. Candidates for the three-phonon states, as well as the lowest members of the intruder band in 120Cd, are also presented. These data support the coexistence of quadrupole anharmonic vibration and proton particle-hole intruder excitations in 118,120Cd.

  1. Rf beam control for the AGS Booster

    SciTech Connect

    Brennan, J.M.

    1994-09-26

    RF beam control systems for hadron synchrotrons have evolved over the past three decades into an essentially standard design. The key difference between hadron and lepton machines is the absence of radiation damping and existence of significant frequency variation in the case of hadrons. Although the motion of the hadron in the potential well of the rf wave is inherently stable it is not strongly damped. Damping must be provided by electronic feedback through the accelerating system. This feedback is typically called the phase loop. The technology of the rf beam control system for the AGS Booster synchrotron is described. First, the overall philosophy of the design is explained in terms of a conventional servo system that regulates the beam horizontal position in the vacuum chamber. The concept of beam transfer functions is fundamental to the mathematics of the design process and is reviewed. The beam transfer functions required for this design are derived from first principles. An overview of the beam signal pick-ups and high level rf equipment is given. The major subsystems, the frequency program, the heterodyne system, and beam feedback loops, are described in detail. Beyond accelerating the beam, the rf system must also synchronize the bunches in the Booster to the buckets in the AGS before transfer. The technical challenge in this process is heightened by the need to accomplish synchronization while the frequency is still changing. Details of the synchronization system are given. This report is intended to serve two purposes. One is to document the hardware and performance of the systems that have been built. The other is to serve as a tutorial vehicle from which the non-expert can not only learn the details of this system but also learn the principles of beam control that have led to the particular design choices made.

  2. Enzyme immobilization on Ag nanoparticles/polyaniline nanocomposites.

    PubMed

    Crespilho, Frank N; Iost, Rodrigo M; Travain, Silmar A; Oliveira, Osvaldo N; Zucolotto, Valtencir

    2009-06-15

    We show a simple strategy to obtain an efficient enzymatic bioelectrochemical device, in which urease was immobilized on electroactive nanostructured membranes (ENMs) made with polyaniline and silver nanoparticles (AgNP) stabilized in polyvinyl alcohol (PAni/PVA-AgNP). Fabrication of the modified electrodes comprised the chemical deposition of polyaniline followed by drop-coating of PVA-AgNP and urease, resulting in a final ITO/PAni/PVA-AgNP/urease electrode configuration. For comparison, the electrochemical performance of ITO/PAni/urease electrodes (without Ag nanoparticles) was also studied. The performance of the modified electrodes toward urea hydrolysis was investigated via amperometric measurements, revealing a fast increase in cathodic current with a well-defined peak upon addition of urea to the electrolytic solution. The cathodic currents for the ITO/PAni/PVA-AgNP/urease electrodes were significantly higher than for the ITO/PAni/urease electrodes. The friendly environment provided by the ITO/PAni/PVA-AgNP electrode to the immobilized enzyme promoted efficient catalytic conversion of urea into ammonium and bicarbonate ions. Using the Michaelis-Menten kinetics equation, a K(M)(app) of 2.7 mmol L(-1) was obtained, indicating that the electrode architecture employed may be advantageous for fabrication of enzymatic devices with improved biocatalytic properties.

  3. Nanosilver on nanostructured silica: Antibacterial activity and Ag surface area

    PubMed Central

    Sotiriou, Georgios A.; Teleki, Alexandra; Camenzind, Adrian; Krumeich, Frank; Meyer, Andreas; Panke, Sven; Pratsinis, Sotiris E.

    2013-01-01

    Nanosilver is one of the first nanomaterials to be closely monitored by regulatory agencies worldwide motivating research to better understand the relationship between Ag characteristics and antibacterial activity. Nanosilver immobilized on nanostructured silica facilitates such investigations as the SiO2 support hinders the growth of nanosilver during its synthesis and, most importantly, its flocculation in bacterial suspensions. Here, such composite Ag/silica nanoparticles were made by flame spray pyrolysis of appropriate solutions of Ag-acetate or Ag-nitrate and hexamethyldisiloxane or tetraethylorthosilicate in ethanol, propanol, diethylene glucolmonobutyl ether, acetonitrile or ethylhexanoic acid. The effect of solution composition on nanosilver characteristics and antibacterial activity against the Gram negative Escherichia coli was investigated by monitoring their recombinantly synthesized green fluorescent protein. Suspensions with identical Ag mass concentration exhibited drastically different antibacterial activity pointing out that the nanosilver surface area concentration rather than its mass or molar or number concentration determine best its antibacterial activity. Nanosilver made from Ag-acetate showed a unimodal size distribution, while that made from inexpensive Ag-nitrate exhibited a bimodal one. Regardless of precursor composition or nanosilver size distribution, the antibacterial activity of nanosilver was correlated best with its surface area concentration in solution. PMID:23730198

  4. Prognostic potential of AgNORs in oral submucous fibrosis

    PubMed Central

    Murgod, Sanjay; Channabasaviah, Girish Hemadal; Shivamurthy, Dyamenahalli Malleshappa; Ashok, Lingappa; Krishnappa, Savita Jangal

    2016-01-01

    Aim and Objective: The role of prognosis cannot be stressed enough, especially when it comes to potentially malignant lesions. The argyrophilic nucleolar organizer regions (AgNORs), which is simple and cost-effective has been used in diagnostic and prognostic pathologies. This study seeks to identify the nucleolar organizer regions (NORs) in oral submucous fibrosis (OSMF), to correlate the AgNOR count with the histologic grade of OSMF, and to evaluate the prognostic potential of AgNOR. Materials and Methods: The sample size consisted of archival paraffin blocks of 35 cases of varying grades of OSMF and 10 cases of squamous cell carcinoma. Normal mucosa samples served as controls for the study. AgNOR staining in accordance with the method of Smith and Crocker was performed and Student's t-test was used for statistical analysis. Results: The results showed an increase in AgNOR counts with corresponding grades of OSMF, the count being least in normal mucosa and also an increase in AgNOR count with corresponding decrease in differentiation of oral squamous cell carcinoma. Conclusion: AgNOR staining is a rapid and inexpensive procedure representing cellular proliferation that can be used to assess the nature of the lesion and therefore, the prognosis. PMID:27114958

  5. Nanosilver on nanostructured silica: Antibacterial activity and Ag surface area.

    PubMed

    Sotiriou, Georgios A; Teleki, Alexandra; Camenzind, Adrian; Krumeich, Frank; Meyer, Andreas; Panke, Sven; Pratsinis, Sotiris E

    2011-06-01

    Nanosilver is one of the first nanomaterials to be closely monitored by regulatory agencies worldwide motivating research to better understand the relationship between Ag characteristics and antibacterial activity. Nanosilver immobilized on nanostructured silica facilitates such investigations as the SiO2 support hinders the growth of nanosilver during its synthesis and, most importantly, its flocculation in bacterial suspensions. Here, such composite Ag/silica nanoparticles were made by flame spray pyrolysis of appropriate solutions of Ag-acetate or Ag-nitrate and hexamethyldisiloxane or tetraethylorthosilicate in ethanol, propanol, diethylene glucolmonobutyl ether, acetonitrile or ethylhexanoic acid. The effect of solution composition on nanosilver characteristics and antibacterial activity against the Gram negative Escherichia coli was investigated by monitoring their recombinantly synthesized green fluorescent protein. Suspensions with identical Ag mass concentration exhibited drastically different antibacterial activity pointing out that the nanosilver surface area concentration rather than its mass or molar or number concentration determine best its antibacterial activity. Nanosilver made from Ag-acetate showed a unimodal size distribution, while that made from inexpensive Ag-nitrate exhibited a bimodal one. Regardless of precursor composition or nanosilver size distribution, the antibacterial activity of nanosilver was correlated best with its surface area concentration in solution.

  6. The Visible-Light Photocatalytic Activity and Antibacterial Performance of Ag/AgBr/TiO2 Immobilized on Activated Carbon.

    PubMed

    Yang, Lu; Ye, Fangyun; Liu, Peng; Wang, Fazhou

    2016-11-01

    Visible-light-driven Ag/AgBr/TiO2 /activated carbon (AC) composite was prepared by solgel method coupled with photoreduction method. For comparison, TiO2 , TiO2 /AC, and Ag/AgBr/TiO2 were also synthesized. Their characteristics were analyzed by XRD, SEM-EDS, TG-DSC and UV-vis techniques. Photocatalytic activity and antibacterial performance under visible-light irradiation were investigated by ICP-AES, ATR-FT-IR and spectrophotometry methods using methylene blue and Escherichia coli as target systems, respectively. The results showed that Ag/AgBr was successfully deposited on anatase TiO2 /AC surface, and exhibited a distinct light absorption in the visible region. Ag/AgBr/TiO2 /AC displayed excellent antibacterial performance both in dark and under visible-light illumination. The growth of E. coli cell was inhibited in the presence of Ag/AgBr/TiO2 /AC in dark. Moreover, upon visible-light illumination, a significant damage of cell membrane was noticed. Ag/AgBr/TiO2 /AC was also shown higher photocatalytic efficiency for methylene blue degradation than those of TiO2 , TiO2 /AC, and Ag/AgBr/TiO2 . This is attributed to the synergetic effect between AC and Ag/AgBr/TiO2 , of which AC acts as the role of increasing reaction areas, continuous enriching, and transferring the adsorbed MB molecules to the surface of supported photocatalysts, and the Ag/AgBr/TiO2 acts as a highly active photocatalyst for degrading MB molecules under visible-light irradiation.

  7. Cyclic voltammetry and near edge X-ray absorption fine structure spectroscopy at the Ag L3-edge on electrochemical halogenation of Ag layers on Au(111)

    NASA Astrophysics Data System (ADS)

    Endo, Osamu; Nakamura, Masashi

    2011-05-01

    One to three layers of Ag grown on a Au(111) electrode were studied by cyclic voltammetry in chloride and bromide solutions and by ex-situ near-edge X-ray absorption fine structure spectroscopy at the Ag L3-edge (Ag L3-NEXAFS). The one and two layers obtained by underpotential deposition exhibited reduced intensity at the absorption edge in the Ag L3-NEXAFS spectra, which suggests the gain of d-electrons in these layers. The cyclic voltammograms and the Ag L3-NEXAFS spectra indicate that the second and third layers of Ag halogenated at positive potentials, whereas the first layer remained in metallic form.

  8. The structure of molten AgCl, AgI and their eutectic mixture as studied by molecular dynamics simulations of polarizable ion model potentials.

    PubMed

    Alcaraz, Olga; Bitrián, Vicente; Trullàs, Joaquim

    2011-01-07

    The structure of molten AgCl, AgI, and their eutectic mixture Ag(Cl(0.43)I(0.57)) is studied by means of molecular dynamics simulations of polarizable ion model potentials. The corresponding static coherent structure factors reproduce quite well the available neutron scattering data. The qualitative behavior of the simulated partial structure factors and radial distribution functions for molten AgCl and AgI is that predicted by the reverse Monte Carlo modeling of the experimental data. The AgI results are also in qualitative agreement with those calculated from ab initio molecular dynamics.

  9. AgCo3PO4(HPO4)2.

    PubMed

    Guesmi, Abderrahmen; Driss, Ahmed

    2002-01-01

    The structure of the hydrothermally synthesized compound AgCo3PO4(HPO4)2, silver tricobalt phosphate bis(hydrogen phosphate), consists of edge-sharing CoO6 chains linked together by the phosphate groups and hydrogen bonds. The three-dimensional framework delimits two types of tunnels which accommodate Ag+ cations and OH groups. The title compound is isostructural with the compounds AM3H2(XO4)3 (A = Na or Ag, M = Co or Mn, and X = P or As) of the alluaudite structure type.

  10. Outburst activity of the symbiiotic binary AG Dra

    NASA Astrophysics Data System (ADS)

    Gális, R.; Hric, L.; Leedjärv, L.; Merc, J.

    2016-03-01

    The outburst activity of the symbiotic system AG Dra has been studied using extensive spectroscopic observational material. High luminosity and temperature of the hot component of AG Dra indicate that quasi-steady thermonuclear shell burning takes place on the surface of the white dwarf. The major (cool) outbursts at the beginning of active phases might occur due to enhanced thermonuclear burning triggered by disk instability. Smaller scale hot outbursts might be explained by the accretion disc instability model like in dwarf novae. We discovered significant similarities in photometric and spectroscopic behaviour of AG Dra and prototypical symbiotic star Z And.

  11. Quasi four-level Tm:LuAG laser

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G. (Inventor); Barnes, Norman P. (Inventor); Hutcheson, Ralph L. (Inventor); Rodriguez, Waldo J. (Inventor)

    1997-01-01

    A quasi four-level solid-state laser is provided. A laser crystal is disposed in a laser cavity. The laser crystal has a LuAG-based host material doped to a final concentration between about 2% and about 7% thulium (Tm) ions. For the more heavily doped final concentrations, the LuAG-based host material is a LuAG seed crystal doped with a small concentration of Tm ions. Laser diode arrays are disposed transversely to the laser crystal for energizing the Tm ions.

  12. Microstructure, mechanical properties, bio-corrosion properties and antibacterial properties of Ti-Ag sintered alloys.

    PubMed

    Chen, Mian; Zhang, Erlin; Zhang, Lan

    2016-05-01

    In this research, Ag element was selected as an antibacterial agent to develop an antibacterial Ti-Ag alloy by a powder metallurgy. The microstructure, phase constitution, mechanical properties, corrosion resistance and antibacterial properties of the Ti-Ag sintered alloys have been systematically studied by X-ray diffraction (XRD), scanning electron microscope (SEM), compressive test, electrochemical measurements and antibacterial test. The effects of the Ag powder size and the Ag content on the antibacterial property and mechanical property as well as the anticorrosion property have been investigated. The microstructure results have shown that Ti-Ag phase, residual pure Ag and Ti were the mainly phases in Ti-Ag(S75) sintered alloy while Ti2Ag was synthesized in Ti-Ag(S10) sintered alloy. The mechanical test indicated that Ti-Ag sintered alloy showed a much higher hardness and the compressive yield strength than cp-Ti but the mechanical properties were slightly reduced with the increase of Ag content. Electrochemical results showed that Ag powder size had a significant effect on the corrosion resistance of Ti-Ag sintered alloy. Ag content increased the corrosion resistance in a dose dependent way under a homogeneous microstructure. Antibacterial tests have demonstrated that antibacterial Ti-Ag alloy was successfully prepared. It was also shown that the Ag powder particle size and the Ag content influenced the antibacterial activity seriously. The reduction in the Ag powder size was benefit to the improvement in the antibacterial property and the Ag content has to be at least 3wt.% in order to obtain a strong and stable antibacterial activity against Staphylococcus aureus bacteria. The bacterial mechanism was thought to be related to the Ti2Ag and its distribution.

  13. Facile synthesis of Ag@Au core-sheath nanowires with greatly improved stability against oxidation.

    PubMed

    Yang, Miaoxin; Hood, Zachary D; Yang, Xuan; Chi, Miaofang; Xia, Younan

    2017-02-07

    We report a facile synthesis of Ag@Au core-sheath nanowires through the conformal deposition of Au atoms onto the surface of pre-synthesized Ag nanowires. The resulting Ag@Au nanowires showed morphology and optical properties almost identical to the pristine Ag nanowires, but with greatly improved stability under different corrosive environments.

  14. Effects of reducing agents on the synthesis of Ag/rGO nanocomposites

    NASA Astrophysics Data System (ADS)

    Li, Yaya; Song, Qiong; Fan, Bingbing; Zhang, Rui

    2017-01-01

    A facile and rapid microwave-assisted green route has been used for the formation of Ag nanoparticles (AgNPs) and the reduction of graphene oxide (GO) simultaneously with five different reducing agents, sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium citrate, urea and ascorbic acid. The experimental results show that the structural properties and phase of Ag/reduced graphene oxide (Ag/rGO) nanocomposites are connected with reducing agent. AgNPs can be uniformly and compactly anchored on reduced GO (rGO) surface in the microwave field for 2 min by the assist of NaOH or KOH as reducing agent. The OH‑ can not only accelerate the ionization of acidic functional groups but also act as the nucleophile for Ag+. By addition of sodium citrate and urea, the GO sample remains its original structure, and Ag+ tends to form Ag2CO3, which then decomposes into Ag2O. While in the urea solution, Ag2O turns into [Ag(NH3)2]+ ions with abundant urea, then [Ag(NH3)2]+ ions are reduced to Ag0 by electrons, which leads to both Ag and Ag2O phase coexisting in the urea treated samples. In addition, it can be found that NaOH shows the best results in terms of the crystallinity and purity of Ag grains anchored on rGO surface.

  15. Ag Nanoparticles (Ag NM300K) in the Terrestrial Environment: Effects at Population and Cellular Level in Folsomia candida (Collembola)

    PubMed Central

    Mendes, Luís André; Maria, Vera L.; Scott-Fordsmand, Janeck J.; Amorim, Mónica J. B.

    2015-01-01

    The effects of nanomaterials have been primarily assessed based on standard ecotoxicity guidelines. However, by adapting alternative measures the information gained could be enhanced considerably, e.g., studies should focus on more mechanistic approaches. Here, the environmental risk posed by the presence of silver nanoparticles (Ag NM300K) in soil was investigated, anchoring population and cellular level effects, i.e., survival, reproduction (28 days) and oxidative stress markers (0, 2, 4, 6, 10 days). The standard species Folsomia candida was used. Measured markers included catalase (CAT), glutathione reductase (GR), glutathione S-transferase (GST), total glutathione (TG), metallothionein (MT) and lipid peroxidation (LPO). Results showed that AgNO3 was more toxic than AgNPs at the population level: reproduction EC20 and EC50 was ca. 2 and 4 times lower, respectively. At the cellular level Correspondence Analysis showed a clear separation between AgNO3 and AgNP throughout time. Results showed differences in the mechanisms, indicating a combined effect of released Ag+ (MT and GST) and of AgNPs (CAT, GR, TG, LPO). Hence, clear advantages from mechanistic approaches are shown, but also that time is of importance when measuring such responses. PMID:26473892

  16. Visible light driven Ag/Ag3PO4/AC photocatalyst with highly enhanced photodegradation of tetracycline antibiotics

    NASA Astrophysics Data System (ADS)

    Wang, Huiqin; Ye, Zhefei; Liu, Chun; Li, Jinze; Zhou, Mingjun; Guan, Qingfeng; Lv, Peng; Huo, Pengwei; Yan, Yongsheng

    2015-10-01

    Ag/Ag3PO4/active carbon (AC) composite photocatalysts were successfully synthesized using the simple deposition and photoinduced methods. The structures, morphology and photocatalytic properties of as-prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS). The Ag/Ag3PO4/AC composite photocatalysts exhibited a conspicuously improved photocatalytic performance for tetracycline (TC) degradation. The optimal conditions of loaded dosage and photoinduced time were investigated, and the results showed that the photoinduced time played an important role in prepared processes, and also that for the loaded dosage of Ag3PO4. The DRS analysis showed that the composite photocatalysts exhibited strong absorption ability in the visible light range. The radicals trap experiments demonstrated that there were multiple active species during the degrading process of TC. The possible mechanism of improved photocatalytic activity of Ag-Ag3PO4/AC composite was also proposed.

  17. Preparation of AgBr Nanoparticles in Microemulsions Via Reaction of AgNO3 with CTAB Counterion

    NASA Astrophysics Data System (ADS)

    Husein, Maen M.; Rodil, Eva; Vera, Juan H.

    2007-10-01

    Nanoparticles of AgBr were prepared by precipitating AgBr in the water pools of microemulsions consisting of CTAB, n-butanol, isooctane and water. An aqueous solution of AgNO3 added to the microemulsion was the source of Ag+ ions. The formation of AgBr nanoparticles in microemulsions through direct reaction with the surfactant counterion is a novel approach aimed at decreasing the role of intermicellar nucleation on nanoparticle formation for rapid reactions. The availability of the surfactant counterion in every reverse micelle and the rapidity of the reaction with the counterion trigger nucleation within individual reverse micelles. The effect of the following variables on the particle size and size distribution was investigated: the surfactant and cosurfactant concentrations, moles of AgNO3 added, and water to surfactant mole ratio, R. High concentration of the surfactant or cosurfactant, or high water content of the microemulsion favored intermicellar nucleation and resulted in the formation of large particles with broad size distribution, while high amounts of AgNO3 favored nucleation within individual micelles and resulted in small nanoparticles with narrow size distribution. A blue shift in the UV absorption threshold corresponding to a decrease in the particle size was generally observed. Notably, the variation of the absorption peak size with the nanoparticle size was opposite to those reported by us in previous studies using different surfactants.

  18. Work Function Reduction by BaO: Growth of Crystalline Barium Oxide on Ag(001) and Ag(111) Surfaces

    SciTech Connect

    Droubay, Timothy C.; Kong, Lingmei; Chambers, Scott A.; Hess, Wayne P.

    2015-02-01

    Ultrathin films of barium oxide were grown on Ag(001) and Ag(111) using the evaporation of Ba metal in an O2 atmosphere by molecular beam epitaxy. Ultraviolet photoemission spectroscopy reveals that films consisting of predominantly BaO or BaO2 result in Ag(001) work function reductions of 1.74 eV and 0.64 eV, respectively. On the Ag(001) surface, Ba oxide growth is initiated by two-dimensional nucleation of epitaxial BaO, followed by a transition to three-dimensional dual-phase nucleation of epitaxial BaO and BaO2. Three-dimensional islands of primarily BaO2(111) nucleate epitaxially on the Ag(111) substrate leaving large patches of Ag uncovered. We find no indication of chemical reaction or charge transfer between the films and the Ag substrates. These data suggest that the origin of the observed work function reduction is largely due to a combination of BaO surface relaxation and an electrostatic compressive effect.

  19. One-step synthesis of Ag/AgCl/GO composite: A photocatalyst of extraordinary photoactivity and stability.

    PubMed

    Liu, Lin; Deng, Jiatao; Niu, Tongjun; Zheng, Gang; Zhang, Pei; Jin, Yong; Jiao, Zhifeng; Sun, Xiaosong

    2017-05-01

    Recently, the photocatalytic applications of silver chloride have been paid closed attention for the excellent ability to photodegrade organic pollutants. Comparing with other catalysts, the silver chloride presents outstanding photocatalytic activity. However, it also suffers from the poor photocatalytic stability. This very paper is focusing on the one-step wet chemical process of preparing Ag/AgCl/GO photocatalyst with high photocatalytic activity and stability. The detailed characterizations were particularly carried out in order to investigate the photo-catalytic activity and stability. Meanwhile the morphology, chemical composition as well as crystalline structure were investigated. It is found that the as-prepared Ag/AgCl/GO composite exhibited an ultrahigh photocatalytic activity and stability in the process of photodegrading RhB. The unique catalytic activity has been discussed based on the SPR effect in Ag nanoparticles on AgCl surface and the separation of photo-generated electron-hole pairs, the primary benefit of the stability owes a great deal to GO which can capture the photo-generated electrons in case they reduce Ag(+) ion or recombine the excited holes.

  20. Silver bioaccumulation dynamics in a freshwater invertebrate after aqueous and dietary exposures to nanosized and ionic Ag

    USGS Publications Warehouse

    le Croteau, Marie-Noe; Misra, Superb K.; Luoma, Samuel N.; Valsami-Jones, Eugenia

    2011-01-01

    We compared silver (Ag) bioavailability and toxicity to a freshwater gastropod after exposure to ionic silver (Ag+) and to Ag nanoparticles (Ag NPs) capped with citrate or with humic acid. Silver form, exposure route, and capping agent influence Ag bioaccumulation dynamics in Lymnaea stagnalis. Snails efficiently accumulated Ag from all forms after either aqueous or dietary exposure. For both exposure routes, uptake rates were faster for Ag+ than for Ag NPs. Snails efficiently assimilated Ag from Ag NPs mixed with diatoms (assimilation efficiency (AE) ranged from 49 to 58%) and from diatoms pre-exposed to Ag+ (AE of 73%). In the diet, Ag NPs damaged digestion. Snails ate less and inefficiently processed the ingested food, which adversely impacted their growth. Loss rates of Ag were faster after waterborne exposure to Ag NPs than after exposure to dissolved Ag+. Once Ag was taken up from diet, whether from Ag+ or Ag NPs, Ag was lost extremely slowly. Large Ag body concentrations are thus expected in L. stagnalis after dietborne exposures, especially to citrate-capped Ag NPs. Ingestion of Ag associated with particulate materials appears as the most important vector of uptake. Nanosilver exposure from food might trigger important environmental risks.

  1. Diffusion and solid state reactions in Fe/Ag/Pt and FePt/Ag thin-film systems

    NASA Astrophysics Data System (ADS)

    Katona, G. L.; Safonova, N. Y.; Ganss, F.; Mitin, D.; Vladymyrskyi, I. A.; Sidorenko, S. I.; Makogon, Iu N.; Beddies, G.; Albrecht, M.; Beke, D. L.

    2015-05-01

    Depth profiles of tri-layered Fe(15 nm)/Ag(10 nm)/Pt(15 nm)/SiO2(100 nm)/Si(1 0 0) and bi-layered Fe50Pt50(15 nm)/Ag(7.5 nm)/SiO2(100 nm)/Si(1 0 0) thin films after different heat treatments were investigated by secondary neutral mass spectrometry. Isotherm annealing of the tri-layered samples was carried out between 245 and 390 °C up to several hours, while isochrone thermal annealing was performed between 600 and 900 °C for 30 s. Composition profiles, obtained after isotherm heat treatment, show that initially there was a strong intermixing between Ag and Pt, resulting most likely in the formation of an AgxPt1-x reaction layer. Furthermore, the intermixing process was much faster in the Ag layer accompanied by the segregation of Ag to the substrate/Pt interface. Later on the Pt, which diffused through the Ag layer, started to penetrate into the Fe grain boundaries. This process led to the formation of the FePt reaction product. At the same time as the Pt diffused into the Fe layer, reducing the amount of Pt in the AgxPt1-x layer, the Ag appeared to ‘move’ towards the substrate. Finally, an almost fully homogeneous FePt alloy layer formed with some FePt present in the grain boundaries of the remaining Ag. This behavior was compared to both types of samples subjected to isochrone thermal annealing. High temperature treatments resulted in similar results and eventually in the formation of a homogeneous L10 ordered FePt alloy with randomly distributed Ag in the grain boundaries and at the free surface.

  2. Pd effect on reliability of Ag bonding wires in microelectronic devices in high-humidity environments

    NASA Astrophysics Data System (ADS)

    Cho, Jong-Soo; Yoo, Kyung-Ah; Moon, Jeong-Tak; Son, Seoung-Bum; Lee, Se-Hee; Oh, Kyu Hwan

    2012-10-01

    We investigated the effect of Pd concentration in Pd-doped Ag wires on the humidity reliability and interfacial corrosion characteristics between Ag wire and Al metallization. Additionally, we confirmed no corrosion problem between Ag wire and noble metal (Pd, Au) metallization, even after a pressure cooker test (PCT). The chemical composition of the tested Ag wires was pure Ag, Ag-1wt% Pd and Ag-3wt% Pd. These wires were bonded to Al and noble metal (Au, Pd) metallization using a thermo-sonic bonder. The interfaces were characterized by focused ion beam (FIB), high resolution transmission electron microscope (HRTEM) and energy dispersive X-ray spectroscopy (EDS). The interface corrosion of Pd doped Ag wires was significantly reduced as the Pd concentration in the Ag wires increased. Furthermore, the Ag wires on the noble metal (Au, Pd) metallization exhibited stable reliability during the PCT.

  3. Thermodynamic properties of the intermediate phases of the Ag-Sb-Se system

    NASA Astrophysics Data System (ADS)

    Moroz, M. V.; Prokhorenko, M. V.

    2014-05-01

    The emf (ɛ) dependence of C|Ag|AgI|glass Ag2GeS3| D|C galvanic elements on temperature is studied in the range of 470 to 575 K (C represents current electrodes, D denotes equilibrium three-phase alloys of individual Ag-Sb-Se systems, and AgI|glass Ag2GeS3 is a bilayer membrane with purely ionic (Ag+) electroconductivity). Analytical equations ɛ = ɛ( T) are used to calculate the thermodynamic functions of saturated solid solutions of the AgSbSe2, Sb2Se3, and Ag2Se phases of the Ag-Sb-Se system in the standard state.

  4. The Ratio of 2-AG to Its Isomer 1-AG as an Intrinsic Fine Tuning Mechanism of CB1 Receptor Activation

    PubMed Central

    Dócs, Klaudia; Mészár, Zoltán; Gonda, Sándor; Kiss-Szikszai, Attila; Holló, Krisztina; Antal, Miklós; Hegyi, Zoltán

    2017-01-01

    Endocannabinoids are pleiotropic lipid messengers that play pro-homeostatic role in cellular physiology by strongly influencing intracellular Ca2+ concentration through the activation of cannabinoid receptors. One of the best-known endocannabinoid ‘2-AG’ is chemically unstable in aqueous solutions, thus its molecular rearrangement, resulting in the formation of 1-AG, may influence 2-AG-mediated signaling depending on the relative concentration and potency of the two isomers. To predict whether this molecular rearrangement may be relevant in physiological processes and in experiments with 2-AG, here we studied if isomerization of 2-AG has an impact on 2-AG-induced, CB1-mediated Ca2+ signaling in vitro. We found that the isomerization-dependent drop in effective 2-AG concentration caused only a weak diminution of Ca2+ signaling in CB1 transfected COS7 cells. We also found that 1-AG induces Ca2+ transients through the activation of CB1, but its working concentration is threefold higher than that of 2-AG. Decreasing the concentration of 2-AG in parallel to the prevention of 1-AG formation by rapid preparation of 2-AG solutions, caused a significant diminution of Ca2+ signals. However, various mixtures of the two isomers in a fix total concentration – mimicking the process of isomerization over time – attenuated the drop in 2-AG potency, resulting in a minor decrease in CB1 mediated Ca2+ transients. Our results indicate that release of 2-AG into aqueous medium is accompanied by its isomerization, resulting in a drop of 2-AG concentration and simultaneous formation of the similarly bioactive isomer 1-AG. Thus, the relative concentration of the two isomers with different potency and efficacy may influence CB1 activation and the consequent biological responses. In addition, our results suggest that 1-AG may play role in stabilizing the strength of cannabinoid signal in case of prolonged 2-AG dependent cannabinoid mechanisms. PMID:28265242

  5. Synergistic photocatalytic inactivation mechanisms of bacteria by graphene sheets grafted plasmonic AgAgX (X = Cl, Br, I) composite photocatalyst under visible light irradiation.

    PubMed

    Xia, Dehua; An, Taicheng; Li, Guiying; Wang, Wanjun; Zhao, Huijun; Wong, Po Keung

    2016-08-01

    By coupling graphene sheet and plasmonic photocatalysis technologies, a series of AgAgX/RGOs (X = Cl, Br, I; RGO = reduced graphene oxide) composites were prepared and found to be efficient antimicrobial agents for water disinfection upon visible light. Attributed to the efficient charge transfer by RGO sheets, the optimum AgAgBr/0.5% RGO could completely inactivate 2 × 10(7) cfu mL(-1) of Escherichia coli within 8 min, much faster than bare AgAgBr within 35 min. The synergistic antimicrobial mechanism of AgAgBr/0.5% RGO was studied by Ag(+) ions release evaluation, radical scavengers study, and radical determination. The enhanced photocatalytic activity of irradiated AgAgBr/0.5% RGO originated from the synergistic activities of its three components including Ag, AgBr and RGO, and the proposed mechanisms contained enhanced attraction by RGO followed by two pathways: primary oxidative stress caused by plasma induced reactive species like H2O2 and bactericidal effect of released Ag(+) ions. Furthermore, characterization of E. coli cells using SEM, fluorescent microscopy, and cytoplasmic substance leakage illustrated that VL irradiated AgAgBr/0.5% RGO could not only cause metabolic dysfunction but also destroy the cell envelope and biomolecular, while irradiated Ag(+) ions play a differential bactericidal action with a limited metabolic injury and no cell-membrane damage. The present work provides an efficient water disinfection technology and also opens a new idea in studying the antimicrobial mechanism of plasmonic photocatalyst.

  6. Investigation of Ag-TiO2 Interfacial Reaction of Highly Stable Ag Nanowire Transparent Conductive Film with Conformal TiO2 Coating by Atomic Layer Deposition.

    PubMed

    Yeh, Ming-Hua; Chen, Po-Hsun; Yang, Yi-Ching; Chen, Guan-Hong; Chen, Hsueh-Shih

    2017-03-29

    The atomic layer deposition (ALD) technique is applied to coat Ag nanowires (NWs) with a highly uniform and conformal TiO2 layer to improve the stability and sustainability of Ag NW transparent conductive films (TCFs) at high temperatures. The TiO2 layer can be directly deposited on Ag NWs with a surface polyvinylpyrrolidone (PVP) coat that acts a bed for TiO2 seeding in the ALD process. The ALD TiO2 layer significantly enhances the thermal stability at least 100 fold when aged between 200-400 °C and also provides an extra function of violet-blue light filtration for Ag NW TCFs. Investigation into the interaction between TiO2 and Ag reveals that the conformal TiO2 shell could effectively prevent Ag from 1D-to-3D ripening. However, Ag could penetrate the conformal TiO2 shell and form nanocrystals on the TiO2 shell surface when it is aged at 400 °C. According to experimental data and thermodynamic evaluation, the Ag penetration leads to an interlayer composed of mixed Ag-Ag2O-amorphous carbon phases and TiO2-x at the Ag-TiO2 interface, which is thought to be caused by extremely high vapor pressure of Ag at the Ag-TiO2 interface at a higher temperature (e.g., 400 °C).

  7. Fabrication of Z-scheme plasmonic photocatalyst Ag@AgBr/g-C₃N₄ with enhanced visible-light photocatalytic activity.

    PubMed

    Yang, Yuxin; Guo, Wan; Guo, Yingna; Zhao, Yahui; Yuan, Xing; Guo, Yihang

    2014-04-30

    A series of Ag@AgBr grafted graphitic carbon nitride (Ag@AgBr/g-C3N4) plasmonic photocatalysts are fabricated through photoreducing AgBr/g-C3N4 hybrids prepared by deposition-precipitation method. The phase and chemical structures, electronic and optical properties as well as morphologies of Ag@AgBr/g-C3N4 heterostructures are well-characterized. Subsequently, the photocatalytic activity of Ag@AgBr/g-C3N4 is evaluated by the degradation of methyl orange (MO) and rhodamin B (RB) under visible-light irradiation. The enhanced photocatalytic activity of Ag@AgBr/g-C3N4 compared with g-C3N4 and Ag@AgBr is obtained and explained in terms of the efficient visible-light utilization efficiency as well as the construction of Z-scheme, which keeps photogenerated electrons and holes with high reduction and oxidation capability, evidenced by photoelectrochemical tests and free radical and hole scavenging experiments. Based on the intermediates identified in the reaction system, the photocatalytic degradation pathway of MO is put forward.

  8. Degradation of microcystin-LR by highly efficient AgBr/Ag3PO4/TiO2 heterojunction photocatalyst under simulated solar light irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Utsumi, Motoo; Yang, Yingnan; Li, Dawei; Zhao, Yingxin; Zhang, Zhenya; Feng, Chuanping; Sugiura, Norio; Cheng, Jay Jiayang

    2015-01-01

    A novel photocatalyst AgBr/Ag3PO4/TiO2 was developed by a simple facile in situ deposition method and used for degradation of mirocystin-LR. TiO2 (P25) as a cost effective chemical was used to improve the stability of AgBr/Ag3PO4 under simulated solar light irradiation. The photocatalytic activity tests for this heterojunction were conducted under simulated solar light irradiation using methyl orange as targeted pollutant. The results indicated that the optimal Ag to Ti molar ratio for the photocatalytic activity of the resulting heterojunction AgBr/Ag3PO4/TiO2 was 1.5 (named as 1.5 BrPTi), which possessed higher photocatalytic capacity than AgBr/Ag3PO4. The 1.5 BrPTi heterojunction was also more stable than AgBr/Ag3PO4 in photocatalysis. This highly efficient and relatively stable photocatalyst was further tested for degradation of the hepatotoxin microcystin-LR (MC-LR). The results suggested that MC-LR was much more easily degraded by 1.5 BrPTi than by AgBr/Ag3PO4. The quenching effects of different scavengers proved that reactive h+ and •OH played important roles for MC-LR degradation.

  9. Influence of the surface properties on bactericidal and fungicidal activity of magnetron sputtered Ti-Ag and Nb-Ag thin films.

    PubMed

    Wojcieszak, D; Mazur, M; Kaczmarek, D; Mazur, P; Szponar, B; Domaradzki, J; Kepinski, L

    2016-05-01

    In this study the comparative investigations of structural, surface and bactericidal properties of Ti-Ag and Nb-Ag thin films have been carried out. Ti-Ag and Nb-Ag coatings were deposited on silicon and fused silica substrates by magnetron co-sputtering method using innovative multi-target apparatus. The physicochemical properties of prepared thin films were examined with the aid of X-ray diffraction, grazing incidence X-ray diffraction, scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy methods. Moreover, the wettability of the surface was determined. It was found that both, Ti-Ag and Nb-Ag thin films were nanocrystalline. In the case of Ag-Ti film presence of AgTi3 and Ag phases was identified, while in the structure of Nb-Ag only silver occurred in a crystal form. In both cases the average size of crystallites was ca. 11 nm. Moreover, according to scanning electron microscopy and atomic force microscopy investigations the surface of Nb-Ag thin films was covered with Ag-agglomerates, while Ti-Ag surface was smooth and devoid of silver particles. Studies of biological activity of deposited coatings in contact with Bacillus subtilis, Pseudomonas aeruginosa, Enterococcus hirae, Klebisiella pneumoniae, Escherichia coli, Staphylococcus aureus and Candida albicans were performed. It was found that prepared coatings were bactericidal and fungicidal even in a short term-contact, i.e. after 2 h.

  10. Global optimization of bimetallic cluster structures. I. Size-mismatched Ag-Cu, Ag-Ni, and Au-Cu systems.

    PubMed

    Rapallo, Arnaldo; Rossi, Giulia; Ferrando, Riccardo; Fortunelli, Alessandro; Curley, Benjamin C; Lloyd, Lesley D; Tarbuck, Gary M; Johnston, Roy L

    2005-05-15

    A genetic algorithm approach is applied to the optimization of the potential energy of a wide range of binary metallic nanoclusters, Ag-Cu, Ag-Ni, Au-Cu, Ag-Pd, Ag-Au, and Pd-Pt, modeled by a semiempirical potential. The aim of this work is to single out the driving forces that make different structural motifs the most favorable at different sizes and chemical compositions. Paper I is devoted to the analysis of size-mismatched systems, namely, Ag-Cu, Ag-Ni, and Au-Cu clusters. In Ag-Cu and Ag-Ni clusters, the large size mismatch and the tendency of Ag to segregate at the surface of Cu and Ni lead to the location of core-shell polyicosahedral minimum structures. Particularly stable polyicosahedral clusters are located at size N = 34 (at the composition with 27 Ag atoms) and N = 38 (at the composition with 32 and 30 Ag atoms). In Ag-Ni clusters, Ag32Ni13 is also shown to be a good energetic configuration. For Au-Cu clusters, these core-shell polyicosahedra are less common, because size mismatch is not reinforced by a strong tendency to segregation of Au at the surface of Cu, and Au atoms are not well accommodated upon the strained polyicosahedral surface.

  11. Synthesis and characterization of cube-like Ag@AgCl-doped TiO2/fly ash cenospheres with enhanced visible-light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Liu, Shaomin; Zhu, Jinglin; Yang, Qing; Xu, Pengpeng; Ge, Jianhua; Guo, Xuetao

    2016-03-01

    A cube-like Ag@AgCl-doped TiO2/fly ash cenosphere composite (denoted Ag@AgCl-TiO2/fly ash cenospheres) was successfully synthesized via a two-step approach. The as-prepared catalysts were characterized by scanning electron microscopy, X-ray diffraction, diffuse reflectance ultraviolet-visible spectroscopy, Brunauer-Emmett-Teller, and X-ray photoelectron spectroscopy. The photocatalytic experiment showed that the rhodamine B degradation rate with Ag@AgCl-TiO2/fly ash cenospheres was 1.56 and 1.33 times higher than that with AgCl-TiO2/fly ash cenospheres and Ag@AgCl, respectively. The degradation ratio of rhodamine B with Ag@AgCl-TiO2/fly ash cenospheres was nearly 100% within 120 min under visible light. Analysis of active species indicated that radO2- and h+ dominated the reaction, and radOH participated in the photocatalytic reactions as an active species. A mechanism for the photocatalytic degradation by the Ag@AgCl-TiO2/fly-ash cenospheres was also proposed based on the experimental results.

  12. In situ ion exchange synthesis of strongly coupled Ag@AgCl/g-C₃N₄ porous nanosheets as plasmonic photocatalyst for highly efficient visible-light photocatalysis.

    PubMed

    Zhang, Shouwei; Li, Jiaxing; Wang, Xiangke; Huang, Yongshun; Zeng, Meiyi; Xu, Jinzhang

    2014-12-24

    A novel efficient Ag@AgCl/g-C3N4 plasmonic photocatalyst was synthesized by a rational in situ ion exchange approach between exfoliated g-C3N4 nanosheets with porous 2D morphology and AgNO3. The as-prepared Ag@AgCl-9/g-C3N4 plasmonic photocatalyst exhibited excellent photocatalytic performance under visible light irradiation for rhodamine B degradation with a rate constant of 0.1954 min(-1), which is ∼41.6 and ∼16.8 times higher than those of the g-C3N4 (∼0.0047 min(-1)) and Ag/AgCl (∼0.0116 min(-1)), respectively. The degradation of methylene blue, methyl orange, and colorless phenol further confirmed the broad spectrum photocatalytic degradation abilities of Ag@AgCl-9/g-C3N4. These results suggested that an integration of the synergetic effect of suitable size plasmonic Ag@AgCl and strong coupling effect between the Ag@AgCl nanoparticles and the exfoliated porous g-C3N4 nanosheets was superior for visible-light-responsive and fast separation of photogenerated electron-hole pairs, thus significantly improving the photocatalytic efficiency. This work may provide a novel concept for the rational design of stable and high performance g-C3N4-based plasmonic photocatalysts for unique photochemical reaction.

  13. Speciation and Lability of Ag-, AgCl- and Ag2S-Nanoparticles in Soil Determined by X-ray Absorption Spectroscopy and Diffusive Gradients in Thin Films

    EPA Science Inventory

    Long-term speciation and lability of silver (Ag-), silver chloride (AgCl-) and silver sulfide nanoparticles (Ag2S-NPs) in soil were studied by X-ray absorption spectroscopy (XAS), and newly developed "nano" Diffusive Gradients in Thin Films (DGT) devices. These nano-D...

  14. Lifetime measurements and magnetic rotation in 107Ag

    NASA Astrophysics Data System (ADS)

    Yao, S. H.; Ma, H. L.; Zhu, L. H.; Wu, X. G.; He, C. Y.; Zheng, Y.; Zhang, B.; Li, G. S.; Li, C. B.; Hu, S. P.; Cao, X. P.; Yu, B. B.; Xu, C.; Cheng, Y. Y.

    2014-01-01

    The excited states in 107Ag were populated through the heavy-ion fusion evaporation reaction 100Mo (11B, 4n) 107Ag at a beam energy of 46 MeV. Lifetimes of high-spin states in 107Ag have been measured through the Doppler shift attenuation method. The deduced B (M1) values, gradually decreasing with increasing spin, clearly demonstrate that both the yrast positive-parity band and the yrast negative-parity band in 107Ag are magnetic rotation bands. Furthermore, experimental deduced B (M1) values for the yrast positive-parity band are compared with the predictions of the particle rotor model. The approximate agreement between theoretical calculations and experimental results further confirms the mechanism of magnetic rotation for the yrast positive-parity band. In addition, a systematic investigation shows the evolution of the magnetic rotation mechanism in the A ≈110 mass region.

  15. Synthesis and characterization of Ag-polymer nanocomposites.

    PubMed

    Mishra, Y K; Mohapatra, S; Chakravadhanula, V S K; Lalla, N P; Zaporojtchenko, V; Avasthi, D K; Faupel, F

    2010-04-01

    We report the synthesis of Ag nanoparticles in polyethylene terephthalate (PET) matrix using atom beam co-sputtering. Metal filling factor was evaluated by Rutherford backscattering spectrometry. Microstructural evolutions of the nanocomposites films were investigated by transmission electron microscopy, which confirmed the formation of irregular shaped Ag nanoparticles. The X-ray photoelectron spectroscopy measurements of the sputter deposited PET film and co-sputtered deposited Ag-PET as well as PET bulk foil (from Goodfellows) were performed to study chemical composition of the nanocomposite films. The optical properties of these nanocomposites were studied by light absorption/transmission, which revealed a narrow transmission of UV light approximately 320 nm and a broad surface plasmon resonance absorption extending up to infrared region (approximately 2400 nm). Swift heavy ion irradiation of Ag-PET nanocomposite resulted in narrowing the full width at half maximum of transmission band.

  16. Metal enhanced fluorescence of Ag-nanoshell dimer

    NASA Astrophysics Data System (ADS)

    Liaw, Jiunn-Woei; Chen, Huang-Chih; Chen, Bae-Renn; Kuo, Mao-Kuen

    2014-04-01

    The plasmon modes of Ag-nanoshell dimer on metal enhanced fluorescence (MEF) are studied theoretically. The amplified excitation rate of a dimer (two identical Ag nanoshells) illuminated by a plane wave for exciting a molecule located at the gap center is calculated. Subsequently, the apparent quantum yield of the emission of the excited molecule affected by the dimer is investigated. The multiple multipole method is used for the both simulations. Finally, the enhancement factor of the dimer on the overall photoluminescence of the molecule in terms of the two parameters is evaluated. Our results show that Ag-nanoshell dimer is a dual-band photoluminescence enhancer for MEF at the bonding dipole and quadrupole modes. The former is broadband, and the latter narrowband. Both bands depend on the gap size. Moreover, the average enhancement factor of Ag-nanoshell dimer for MEF with a Stokes shift is discussed.

  17. Synthesis, characterization and SERS activity of Au-Ag nanorods.

    PubMed

    Philip, Daizy; Gopchandran, K G; Unni, C; Nissamudeen, K M

    2008-09-01

    The formation mechanism and morphology of Au-Ag bimetallic colloidal nanoparticles depend on the composition. Ag coated Au colloidal nanoparticles have been prepared by deposition of Ag through chemical reduction on performed Au colloid. The composition of the Au100-x-Agx particles was varied from x=0 to 50. The obtained colloids were characterized by UV-vis spectroscopy and transmission electron microscopy (TEM). The Au80-Ag20 colloid consists of alloy nanorods with dimension of 25nm x 100nm. The activity of these nanorods in surface enhanced Raman spectroscopy (SERS) was checked by using sodium salicylate as an adsorbate probe. Intense SERS bands are observed indicating its usefulness as a SERS substrate in near infrared (NIR) laser excitation.

  18. Dislocation interactions with characteristic interfaces in AgCu eutectic

    NASA Astrophysics Data System (ADS)

    Eftink, Benjamin P.

    In the AgCu eutectic alloy, the observation of deformation twinning in Cu proposed to be induced by direct transmission of deformation twinning partial dislocations in Ag highlights the question of how interfaces in bi-phase materials respond to deformation. AgCu eutectic alloy was produced by both directional solidification and cast water-quenching. Control over processing variables enabled the synthesis of Ag/Cu eutectic with three predominant interface types: ones with a cube-on-cube orientation relationship with {111} Ag||{111}Cu interface habit planes, twin orientation relationship with {111}Ag||{111}Cu interface habit planes, and twin orientation relationship with near {313}Ag||{ 112}Cu interface habit planes. How dislocations interacted with each of the interfaces was determined using in situ and ex situ TEM straining experiments. It was determined that how strain transfers across Ag/Cu interfaces is consistent with criteria of strain transfer across grain boundaries in single phase materials. Specifically, the magnitude of the Burgers vector of the residual dislocation, |bres |, left in the interface should be small. This criterion was determining enough to drive Cu to twin under conditions where otherwise it would not. When transmission of a dislocation would result in a high |bres|, which is common for most slip systems encountering an incoherent twin interface, the interfaces were observed to block the dislocations. It was found that the increased effectiveness of the incoherent twin interfaces to block dislocations compared to the cube-on-cube interfaces resulted in an increased in the yield strength of the material. Interfaces with the cube-on-cube orientation relationship and mutual {111} interface plane between Ag and Cu results in transfer of twinning defects from Ag into Cu. This was found at length scales in the tens of nano-meters to the micron range. Twinning in both phases was observed after both split-Hopkinson pressure bar ex situ straining

  19. Silver delafossite nitride, AgTaN{sub 2}?

    SciTech Connect

    Miura, Akira; Lowe, Michael; Leonard, Brian M.; Subban, Chinmayee V.; Masubuchi, Yuji; Kikkawa, Shinichi; Dronskowski, Richard; Hennig, Richard G.; Abruna, Hector D.; DiSalvo, Francis J.

    2011-01-15

    A new silver nitride, AgTaN{sub 2}, was synthesized from NaTaN{sub 2} by a cation-exchange reaction, using a AgNO{sub 3}-NH{sub 4}NO{sub 3} flux at 175 {sup o}C. Its crystal structure type is delafossite (R3-bar m) with hexagonal lattice parameters of a=3.141(3) A, c=18.81(2) A, in which silver is linearly coordinated to nitrogen. Energy dispersive X-ray analysis and combustion nitrogen/oxygen analysis gave a composition with atomic ratios of Ag:Ta:N:O as 1.0:1.2(1):2.1(1):0.77(4), which is somewhat Ta rich and indicates some oxide formation. The X-ray photoelectron spectroscopy analysis showed a Ta- and O-rich surface and transmission electron microscope observation exhibited aggregates of ca. 4-5 nm-sized particles on the surface, which are probably related to the composition deviation from a AgTaN{sub 2}. The lattice parameters of stoichiometric AgTaN{sub 2} calculated by density functional theory agree with the experimental ones, but the possibility of some oxygen incorporation and/or silver deficiency is not precluded. -- Graphical abstract: A delafossite silver nitride, AgTaN{sub 2}, was synthesized from NaTaN{sub 2} by a cation-exchange reaction using a AgNO{sub 3}-NH{sub 4}NO{sub 3} flux. It contains N-Ag-N linear bonding. Display Omitted

  20. Outburst Activity of the Symbiotic System AG Dra

    NASA Astrophysics Data System (ADS)

    Gális, R.; Hric, L.; Leedjärv, L.; Kundra, E.

    2015-07-01

    AG Dra is one of the best studied symbiotic systems. A period analysis of new and historical photometric data, as well as radial velocities, confirmed the presence of the two periods — about 550 days, caused by orbital motion, and around 350 days, related to pulsations of the cool component of AG Dra. In addition, the active stages change distinctively, but the outbursts recur with periods from 359 to 375 days.

  1. The Booster to AGS beam transfer fast kicker systems

    SciTech Connect

    Zhang, W.; Bunicci, J.; Soukas, A.V.; Zhang, S.Y.

    1992-08-01

    The Brookhaven AGS Booster has a very successful commissioning period in June 1991. The third phase of that commissioning was a beam extraction test. The Booster extraction fast kicker (F3) deflected a 1.2 GeV proton beam from the Booster circulating orbit into the extraction septum aperture, partially down the extraction line to a temporary beam stop. Now, the Booster is committed to the AGS operations program for both heavy ion and proton beams. Thus, the Booster extraction and the corresponding AGS injection systems must operate routinely up to a pulse repetition frequency of 7.5 Hertz, and up to a beam energy of 1.5 Gev. The injection fast kicker is located in the A5 section of the AGS ring and is used to deflect the proton or heavy ion beam into its final AGS closed orbit. A distinctive feature of the AGS injection fast kicker modulators is the tail-bitting function required for proton beam injection. This enables the system to produce a fast current fall time to go along with the high current pulse amplitude with a fast rise time. The AGS injection fast kicker system has three pulse modulators, and each modulator consists of two thyratrons. The main PFN thyratrons switch on the current, and the tail bitting thyratrons are used to force the magnet current to decrease rapidly. Two digital pulse delay generators are used to align the main thyratrons and the tail bitting thyratrons respectively. The system has been tested and installed. The final commissioning of the Booster to AGS beam transfer line and injection is currently being undertaken. In this article, the system design, realization techniques and performance data will be presented.

  2. POLARIZED PROTON ACCELERATION AT THE BROOKHAVEN AGS - AN UPDATE.

    SciTech Connect

    HUANG,H.; AHRENS,L.; ALESSI,J.; BAI,M.; BEEBE-WANG,J.; BROWN,K.A.; GLENN,W.; LUCCIO,A.U.; MACKAY,W.W.; MONTAG,C.; PTITSYN,V.; ROSER,T.; TSOUPAS,N.; ZELENSKI,A.; ZENO,K.; CADMAN,B.; SPINKA,H.; UNDERWOOD,D.; RANJBAR,V.

    2002-06-02

    The RHIC spin design goal assumes 2 x 10{sup 11} proton/bunch with 70% polarization. As the injector to RHIC, polarized protons have been accelerated at the AGS for years to increase the polarization transmission efficiency. Several novel techniques have been applied in the AGS to overcome the intrinsic and imperfection resonances. The present level of accelerator performance is discussed. Progress on understanding the beam polarization behavior is presented. The outlook and future plan are also discussed.

  3. Polarized proton acceleration program at the AGS and RHIC

    SciTech Connect

    Lee, Y.Y.

    1995-06-01

    Presented is an overview of the program for acceleration of polarized protons in the AGS and their injection into the RHIC collider. The problem of depolarizing resonances in strong focusing circulator accelerators is discussed. The intrinsic resonances are jumped over by the fast tune jump, and a partial Siberian Snake is used to compensate for over forty imperfection resonances in the AGS. Two sets of full Siberian Snake and spin rotators will be employed in RHIC.

  4. Radiochemical synthesis of 105gAg-labelled silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Ichedef, C.; Simonelli, F.; Holzwarth, U.; Bagaria, J. Piella; Puntes, V. F.; Cotogno, G.; Gilliland, D.; Gibson, N.

    2013-11-01

    A method for synthesis of radiolabelled silver nanoparticles is reported. The method is based on proton activation of silver metal powder, enriched in 107Ag, with a 30.7 MeV proton beam. At this proton energy 105gAg is efficiently created, mainly via the 107Ag(p,3n)105Cd → 105gAg reaction. 105gAg has a half-life of 41.29 days and emits easily detectable gamma radiation on decay to 105Pd. This makes it very useful as a tracing radionuclide for experiments over several weeks or months. Following activation and a period to allow short-lived radionuclides to decay, the powder was dissolved in concentrated nitric acid in order to form silver nitrate (AgNO3), which was used to synthesise radiolabelled silver nanoparticles via the process of sodium borohydride reduction. For comparison, non-radioactive silver nanoparticles were synthesised using commercially supplied AgNO3 in order to check if the use of irradiated Ag powder as a starting material would alter in any way the final nanoparticle characteristics. Both nanoparticle types were characterised using dynamic light scattering, zeta-potential and X-ray diffraction measurements, while additionally the non-radioactive samples were analysed by transmission electron microscopy and UV-Vis spectrometry. A hydrodynamic diameter of about 16 nm was determined for both radiolabelled and non-radioactive nanoparticles, while the electron microscopy on the non-radioactive samples indicated that the physical size of the metal NPs was (7.3 ± 1.4) nm.

  5. Melting curve of metals Cu, Ag and Au under pressure

    NASA Astrophysics Data System (ADS)

    Tam, Pham Dinh; Hoc, Nguyen Quang; Tinh, Bui Duc; Tan, Pham Duy

    2016-01-01

    In this paper, the dependence of the melting temperature of metals Cu, Ag and Au under pressure in the interval from 0 kbar to 40 kbar is studied by the statistical moment method (SMM). This dependence has the form of near linearity and the calculated slopes of melting curve are 3.9 for Cu, 5.7 for Ag and 6 for Au. These results are in good agreement with the experimental data.

  6. Enhanced Noble Gas Adsorption in Ag@MOF-74Ni

    SciTech Connect

    Liu, Jian; Strachan, Denis M.; Thallapally, Praveen K.

    2014-01-14

    Various amounts of Ag nanoparticles were successfully deposited in porous MOF-74Ni (or Ni/DOBDC) with an auto-reduction method. An optimized silver-loaded MOF-74Ni was shown to have an improved Xe adsorption capacity (15% more) at STP compared to the MOF without silver nanoparticles. The silver-loaded sample also has a higher Xe/Kr selectivity. These results are explained by the stronger interactions between polarizable Xe molecules and the well-dispersed Ag nanoparticles.

  7. Spectroscopic and lasing properties of Ho:Tm:LuAG

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Filer, Elizabeth D.; Naranjo, Felipe L.; Rodriguez, Waldo J.; Kokta, Milan R.

    1993-01-01

    Ho:Tm:LuAG has been grown, examined spectroscopically, and lased at 2.1 microns. Ho:Tm:LuAG was selected for this experimental investigation when quantum-mechanical modeling predicted that it would be a good laser material for Ho laser operation on one of the 5I7 to 5I8 transitions. Lasing was achieved at 2.100 microns, one of the three wavelengths predicted to be most probable for laser action.

  8. Hepatocellular carcinoma HBsAg positive in pregnancy.

    PubMed

    Gonçalves, C S; Pereira, F E; de Vargas, P R; Ferreira, L S

    1984-01-01

    The authors present a case of hepatocellular carcinoma diagnosed in a pregnant woman (four months pregnancy). The clinical evolution was complicated because of a severe hypoglicemia and the patient died 12 weeks after admission. The fetus died before a tentative of surgical delivery. The patient was HBsAg positive and five out of eight sons (inclusively the fetus), were HBsAg positive. There was not indication that the pregnancy had enhanced the tumor evolution.

  9. Coverage induced structural transformations of tetracene on Ag(110).

    PubMed

    Takasugi, Kazushiro; Yokoyama, Takashi

    2016-03-14

    Self-assembly of tetracene on an anisotropic surface of Ag(110) has been investigated using scanning tunneling microscopy and low-energy electron diffraction. We observe multistage structural transformations of the self-assembled tetracene on Ag(110) as a function of molecular coverages, which are accompanied by the changes in molecular orientations. They are analyzed by a balance between multiple molecule-molecule and anisotropic substrate-molecule interactions.

  10. Phase-dependent corrosion of titanium-to-stainless steel joints brazed by Ag-Cu eutectic alloy filler and Ag interlayer

    NASA Astrophysics Data System (ADS)

    Lee, M. K.; Park, J. J.; Lee, J. G.; Rhee, C. K.

    2013-08-01

    The electrochemical corrosion properties of Ti-STS dissimilar joints brazed by a 72Ag-28Cu alloy filler and an Ag interlayer were studied in a 3.5% NaCl solution using potentiodynamic polarization and ac impedance spectroscopy. For a joint with a layered structure of Ti(base)/TiAg/Ag solid solution/Ag-Cu eutectic/STS(base), galvanic corrosion mostly occurred in the TiAg phase with a severe material loss, indicating that the TiAg layer acted as an anode in the galvanic couple in the layered joint. The Ag-rich solid solution layer was also corroded to a certain extent, but the corrosion in this layer was dominated by the selective pitting corrosion of the eutectic Cu-rich phase. With an increase in the brazing temperature, the Cu-rich phases disappeared owing to the enhanced isothermal solidification effect, leading to an improvement of the corrosion resistance.

  11. The isotopic composition and concentration of Ag in iron meteorites and the origin of exotic silver

    NASA Technical Reports Server (NTRS)

    Kaiser, T.; Wasserburg, G. J.

    1983-01-01

    The isotopic composition of Ag and the concentration of Ag and Pd in Canyon Diablo (IA), Grant (IIIB), Santa Clara, Tlacotepec and Warburton Range (IVB), Pinon and Deep Springs (anom) were analyzed. Troilite from Santa Clara and from Grant was also studied. With the exception of IA, all the meteorites were enriched in Ag-107 by about 2%-212% and the ratio of Ag-107/Ag-109 in the metal phase was found to be greater than the terrestrial value. Ag of anomalous isotopic composition was found to be common in all IVB and anomalous meteorites. A correlation of Ag-107/Ag-109 with Pd/Ag was established except for the iron meteorite of Santa Clara. The excess Ag-107 is thought to result from the decay of Pd-107. The Grant data appear to represent a Pd-107-Ag-107 isochron and indicate that the cooling rate at elevated temperatures was rapid enough to preserve the isotopic differences between metal and troilite. The data suggest that Ag in Santa Clara is made up of almost pure Ag-107 produced from Pd-107 decay and Ag-109 produced by nuclear reactions with only a small amount of 'normal' Ag. This indicates an intense energetic particle bombardment history in the early solar system which occurred after the formation of small planetary bodies.

  12. Adsorption, vibration and diffusion of oxygen on Ag(110)

    NASA Astrophysics Data System (ADS)

    Rawal, Takat; Hong, Sampyo; Pulkkinen, Aki; Alatalo, Matti; Rahman, Talat

    2015-03-01

    We have performed density functional theory calculations for the adsorption, vibration and diffusion of oxygen on Ag(110). At low coverage, O2 adsorbs at the four-fold hollow (FFH) with the molecular axis aligned along the [ 1 1 0 ] direction. The dissociation of O2 is easier along the [001] direction than along the [ 1 1 0 ] direction. For O2 species in FFH aligned along the [001] the O-O intra-molecular stretching mode is coupled with the substrate vibration and thus its dissociation can be induced by surface phonon. In addition, O diffusion barrier from FFH to next FFH along the [ 1 1 0 ] is small (0.07 eV only) but is by far larger (0.4 eV) along [001]. On the other hand, O species in the short-bride (SB) site prefers to diffuse along the [001] (to FFH) rather than along the [ 1 1 0 ] direction (to next SB). Finally, the preference of atomic oxygen to form O-Ag-O complex on Ag(110) is responsible for disordering of the surface by means of substantial lateral and vertical displacements of Ag atoms in the topmost layer. In fact, such disordering phase of Ag(110) may act as a precursor of the reconstructed phase of Ag(110). Work supported in part by NSF under Grant CHE-1310327.

  13. Origin of metallicity in atomic Ag wires on Si(557)

    NASA Astrophysics Data System (ADS)

    Krieg, U.; Lichtenstein, T.; Brand, C.; Tegenkamp, C.; Pfnür, H.

    2015-04-01

    We investigated the metallicity of Ag-\\sqrt{3} ordered atomic wires close to one monolayer (ML) coverage, which are formed on Si(557) via self assembly. For this purpose we combined high resolution electron energy loss spectroscopy with tunneling microscopy. By extending the excess Ag coverage up to 0.6 ML on samples annealed at high temperatures where partial desorption occurs, we demonstrate that one-dimensional metallicity in the Ag-\\sqrt{3}× \\sqrt{3} R30° ordered atomic wires on the (111) mini-terraces originates only from Ag atoms in excess of (local) monolayer coverage, which are adsorbed and localized at the highly stepped parts of the Si(557) surface. Thus these Ag atoms act as extrinsic dopants on the atomic scale, causing coverage dependent subband filling and increasing localization as a function of doping concentration. The second layer lattice gas as well as Ag islands on the (111) terraces turn out not to be relevant as dopants. We simulated the peculiar saturation behavior within a modified lattice gas model and give evidence that the preparation dependent saturation of doping is due to changes of average terrace size and step morphology induced by high temperature treatment.

  14. Quantifying the origin of released Ag+ ions from nanosilver.

    PubMed

    Sotiriou, Georgios A; Meyer, Andreas; Knijnenburg, Jesper T N; Panke, Sven; Pratsinis, Sotiris E

    2012-11-13

    Nanosilver is most attractive for its bactericidal properties in modern textiles, food packaging, and biomedical applications. Concerns, however, about released Ag(+) ions during dispersion of nanosilver in liquids have limited its broad use. Here, nanosilver supported on nanostructured silica is made with closely controlled Ag size both by dry (flame aerosol) and by wet chemistry (impregnation) processes without any surface functionalization that could interfere with its ion release. It is characterized by electron microscopy, atomic absorption spectroscopy, and X-ray diffraction, and its Ag(+) ion release in deionized water is monitored electrochemically. The dispersion method of nanosilver in solutions affects its dissolution rate but not the final Ag(+) ion concentration. By systematically comparing nanosilver size distributions to their equilibrium Ag(+) ion concentrations, it is revealed that the latter correspond precisely to dissolution of one to two surface silver oxide monolayers, depending on particle diameter. When, however, the nanosilver is selectively conditioned by either washing or H(2) reduction, the oxide layers are removed, drastically minimizing Ag(+) ion leaching and its antibacterial activity against E. coli . That way the bactericidal activity of nanosilver is confined to contact with its surface rather than to rampant ions. This leads to silver nanoparticles with antibacterial properties that are essential for medical tools and hospital applications.

  15. Nanocomposite Ag-LSM solid oxide fuel cell electrodes

    NASA Astrophysics Data System (ADS)

    Sholklapper, Tal Z.; Radmilovic, Velimir; Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    Advances in infiltration technology have enabled the creation of innovative electrode architectures that are key to highly effective SOFC anodes and cathodes. In this work, an Ag-infiltrated electrode has been created using a pre-sintered porous scandia-stabilized zirconia (SSZ) electrode backbone. The well-sintered SSZ provides a highly connected ion-conducting pathway throughout the electrode, while the nanometer thickness of the Ag particle layer minimizes the oxygen transport resistance that otherwise limits reaction rates in typical Ag composite electrodes. The new Ag composite electrode had minimal activation polarization by 750 °C. The infiltration technology has allowed for incorporation of additional nanoscale electrocatalysts. Here, an Ag-LSM (strontium-doped lanthanum manganate) composite was produced, that takes advantage of each component catalyst and demonstrates a further enhanced effectiveness of the cathode Ag metal catalyst, producing relatively stable cell power densities of 316 mW cm -2 at 0.7 V (and 467 mW cm -2 peak power at ∼0.4 V) for over 500 h.

  16. β - Ag2Te: A topological insulator with strong anisotropy

    NASA Astrophysics Data System (ADS)

    Wang, Lan; Sulaev, Azat; Ren, Peng; Xia, Bin; Lin, Qinghua; Yu, Ting; Qiu, Caiyu; Zhang, Shuang-Yuan; Han, Ming-Yong; Li, Zhipeng; Zhu, Wei Guang; Wu, Qingyu; Feng, Yuan Ping; Shen, Lei; Shen, Shun-Qing

    2013-03-01

    We present evidence of topological surface states in β-Ag2Te through first-principles calculations, periodic quantum interference effect and ambipolar electric field effect in single crystalline nanoribbon. Our first-principles calculations show that β-Ag2Te is a topological insulator with a gapless Dirac cone with strong anisotropy. To experimentally probe the topological surface state, we synthesized high quality β-Ag2Te nanoribbons and performed electron transport measurements. The coexistence of pronounced Aharonov-Bohm oscillations and weak Altshuler-Aronov-Spivak oscillations clearly demonstrates coherent electron transport around the perimeter of β-Ag2Te nanoribbon and therefore the existence of topological surface states, which is further supported by the ambipolar electric field effect for devices fabricated by β-Ag2Te nanoribbons. The experimentally confirmed topological surface states and the theoretically predicted isotropic Dirac cone of β-Ag2Te suggest that the material may be a promising material for fundamental study and future spintronic devices. RCA-08/018 (Singapore), MOE2010-T2-2-059 (Singapore), HKU705150P (Hong Kong), NTU-SUG M4080513

  17. Biosynthesis of Au, Ag and Au-Ag nanoparticles using edible mushroom extract

    NASA Astrophysics Data System (ADS)

    Philip, Daizy

    2009-07-01

    Integration of green chemistry principles to nanotechnology is one of the key issues in nanoscience research. There is growing need to develop environmentally benign metal nanoparticle synthesis process that do not use toxic chemicals in the synthesis protocols to avoid adverse effects in medical applications. Here, it is a report on extracellular synthesis method for the preparation of Au, Ag and Au-Ag nanoparticles in water, using the extract of Volvariella volvacea, a naturally occurring edible mushroom, as reducing and protecting agents. Gold nanoparticles of different sizes (20-150 nm) and shapes from triangular nanoprisms to nearly spherical and hexagonal are obtained by this novel method. The size and shape of gold nanoparticles are also found to depend on temperature of the extract. The silver nanoparticles are spherical with size ˜15 nm. There is increased productivity of nanoparticles as shown by sharp and intense surface plasmon resonance bands for the nanoparticles prepared using an excess of the extract. The Au-Ag nanoparticles prepared by co-reduction has only one plasmon band due to alloying of the constituents. All the synthesized nanoparticles are found to be photoluminescent and are highly crystalline as shown by SAED and XRD patterns with fcc phase oriented along the (1 1 1) plane. FTIR measurements were carried out to identify the possible biomolecules responsible for capping and efficient stabilization of the nanoparticles. It is found that Au nanoparticles are bound to proteins through free amino groups and silver nanoparticles through the carboxylate group of the amino acid residues. The position and intensity of the emission band is found to depend on composition of the nanoparticles indicating the possible use in therapeutic applications.

  18. Integrated mRNA and micro RNA profiling reveals epigenetic mechanism of differential sensitivity of Jurkat T cells to AgNPs and Ag ions.

    PubMed

    Eom, Hyun-Jeong; Chatterjee, Nivedita; Lee, Jeongsoo; Choi, Jinhee

    2014-08-17

    In our previous in vitro study of the toxicity on silver nanoparticles (AgNPs), we observed a dramatically higher sensitivity of Jurkat T cells to AgNPs than to Ag ions, and DNA damage and apoptosis were found to be involved in that toxicity. In this study, to understand underlying mechanism of different sensitivity of Jurket T cells to AgNPs and Ag ions, mRNA microarray and micro RNA microarray were concomitantly conducted on AgNPs and Ag ions exposed Jurkat T cells. Surprisingly only a small number of genes were differentially expressed by exposure to each of the silver (15 altered mRNA by AgNPs exposure, whereas 4 altered mRNA by Ag ions exposure, as determined 1.5-fold change as the cut-off value). miRNA microarray revealed that the expression of 63 miRNAs was altered by AgNPs exposure, whereas that of 32 miRNAs was altered by Ag ions exposure. An integrated analysis of mRNA and miRNA expression revealed that the expression of hsa-miR-219-5p, was negatively correlated with the expression of metallothionein 1F (MT1F) and tribbles homolog 3 (TRIB3), in cells exposed to AgNPs; whereas, the expression of hsa-miR-654-3p was negatively correlated with the expression of mRNA, endonuclease G-like 1 (EDGL1) in cells exposed to Ag ions. Network analysis were further conducted on mRNA-miRNA pairs, which revealed that miR-219-5p-MT1F and -TRIB3 pairs by AgNPs are being involved in various cellular processes, such as, oxidative stress, cell cycle and apoptosis, whereas, miR-654-3p and ENDOGL1 pair by Ag ions generated a much simpler network. The putative target genes of AgNPs-induced miR-504, miR-33 and miR-302 identified by Tarbase 6.0 are also found to be involved in DNA damage and apoptosis. These results collectively suggest that distinct epigenetic regulation may be an underlying mechanism of different sensitivity of Jurkat T cells to AgNPs and Ag ion. Further identification of putative target genes of DE miRNA by AgNPs and Ag ions may provide additional clues for the

  19. A novel P/Ag/Ag2O/Ag3PO4/TiO2 composite film for water purification and antibacterial application under solar light irradiation.

    PubMed

    Zhu, Qi; Hu, Xiaohong; Stanislaus, Mishma S; Zhang, Nan; Xiao, Ruida; Liu, Na; Yang, Yingnan

    2017-01-15

    TiO2-based thin films have been intensively studied in recent years to develop efficient photocatalyst films to degrade refractory organics and inactivate bacteria for wastewater treatment. In the present work, P/Ag/Ag2O/Ag3PO4/TiO2 composite films on the inner-surface of glass tube were successfully prepared via sol-gel approach. P/Ag/Ag2O/Ag3PO4/TiO2 composite films with 3 coating layers, synthesized at 400°C for 2h, showed the optimal photocatalytic performance for rhodamine B (Rh B) degradation. The results indicated that degradation ratio of Rh B by P/Ag/Ag2O/Ag3PO4/TiO2 composite film reached 99.9% after 60min under simulated solar light, while just 67.9% of Rh B was degraded by pure TiO2 film. Moreover, repeatability experiments indicated that even after five recycling runs, the photodegradation ratio of Rh B over composite film maintained at 99.9%, demonstrating its high stability. Photocatalytic inactivation of E. coli with initial concentration of 10(7)CFU/mL also showed around 100% of sterilization ratio under simulated solar light irradiation in 5min by the composite film. The radical trapping experiments implied that the major active species of P/Ag/Ag2O/Ag3PO4/TiO2 composite films were photo-generated holes and O2(-) radicals. The proposed photocatalytic mechanism shows that the transfer of photo-induced electrons and holes may reduce the recombination efficiency of electron-hole pairs and potential photodecomposition of composite film, resulting in enhanced photocatalytic ability of P/Ag/Ag2O/Ag3PO4/TiO2 composite films.

  20. Antibacterial performance of Ag nanoparticles and AgGO nanocomposites prepared via rapid microwave-assisted synthesis method

    NASA Astrophysics Data System (ADS)

    Chook, Soon Wei; Chia, Chin Hua; Zakaria, Sarani; Ayob, Mohd Khan; Chee, Kah Leong; Huang, Nay Ming; Neoh, Hui Min; Lim, Hong Ngee; Jamal, Rahman; Rahman, Raha Mohd Fadhil Raja Abdul

    2012-09-01

    Silver nanoparticles and silver-graphene oxide nanocomposites were fabricated using a rapid and green microwave irradiation synthesis method. Silver nanoparticles with narrow size distribution were formed under microwave irradiation for both samples. The silver nanoparticles were distributed randomly on the surface of graphene oxide. The Fourier transform infrared and thermogravimetry analysis results showed that the graphene oxide for the AgNP-graphene oxide (AgGO) sample was partially reduced during the in situ synthesis of silver nanoparticles. Both silver nanoparticles and AgGO nanocomposites exhibited stronger antibacterial properties against Gram-negative bacteria ( Salmonella typhi and Escherichia coli) than against Gram-positive bacteria ( Staphyloccocus aureus and Staphyloccocus epidermidis). The AgGO nanocomposites consisting of approximately 40 wt.% silver can achieve antibacterial performance comparable to that of neat silver nanoparticles.