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Sample records for quantiferon-tb gold in-tube

  1. Incidence of tuberculosis among children living in contact with smear-positive tuberculosis: Advantages and limits of the Quantiferon TB gold in tube test.

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    Hannoun, Djohar; Boulahbal, Fadila

    2016-12-01

    Children living in contact with smear-positive pulmonary tuberculosis (TB) patients are highly exposed to TB infection. Our objective was to estimate the incidence of TB in children living in contact with a Smear Positive (M+) pulmonary tuberculosis (PTM+) index case during 2years following exposure. This was a descriptive, cohort, prospective, multicenter study of children aged from 6months to 15years in contact with a PTM+ case. The recruitment of children has been based on the diagnosed PTM+ index case and taken in charge by the Services of Control of Tuberculosis and Respiratory Diseases located in Algiers during 2014. Seven centers were selected. All children were tested using the Quantiferon TB gold in tube (QTR) test and the tuberculin skin test (TST). For TST, an induration diameter ⩾10mm was considered positive. We included 456 children living in contact with a PTM+ patient. The results for TST and QFT were available for 319 children. The mean age of the children was 6.7years (standard deviation=3.9). The sex ratio (Male/Female) was 1.26, and 15.8% (50) did not have a Bacilli of Calmette & Guerin (BCG) vaccination scar. Among the children, 46.1% (147) and 43.4% (138) were positive for QFT and TST, respectively, and 6.1% (19) have received isoniazid preventive therapy. Fifty-one children progressed to TB and received antitubercular treatment. We analyzed and compared our results between children who progressed to TB and those who did not progress to TB. Finally, we discuss our methodology and results in relation to the literature. Copyright © 2016.

  2. Negative effect of smoking on the performance of the QuantiFERON TB gold in tube test

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    Aabye Martine G

    2012-12-01

    Full Text Available Abstract Background False negative and indeterminate Interferon Gamma Release Assay (IGRA results are a well documented problem. Cigarette smoking is known to increase the risk of tuberculosis (TB and to impair Interferon-gamma (IFN-γ responses to antigenic challenge, but the impact of smoking on IGRA performance is not known. The aim of this study was to evaluate the effect of smoking on IGRA performance in TB patients in a low and high TB prevalence setting respectively. Methods Patients with confirmed TB from Denmark (DK, n = 34; 20 smokers and Tanzania (TZ, n = 172; 23 smokers were tested with the QuantiFERON-TB Gold In tube (QFT. Median IFN-γ level in smokers and non smokers were compared and smoking was analysed as a risk factor for false negative and indeterminate QFT results. Results Smokers from both DK and TZ had lower IFN-γ antigen responses (median 0.9 vs. 4.2 IU/ml, p = 0.04 and 0.4 vs. 1.6, p  Conclusions Cigarette smoking was associated with false negative and indeterminate IGRA results in both a high and a low TB endemic setting independent of HIV status.

  3. Comparison of tuberculin skin test and quantiferon-TB gold in tube test for diagnosis of latent tuberculosis infection in health care workers: A cross sectional study.

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    Bozkanat, Erkan; Kaya, Hatice; Sezer, Ogun; Caliskan, Tayfun; Kilic, Erol; Ciftci, Faruk; Gumus, Seyfettin; Kartaloglu, Zafer

    2016-03-01

    To compare the diagnostic efficacy and agreement of the traditional tuberculin skin test with QuantiFERON-Tuberculosis Gold In-Tube test for latent tuberculosis infection in healthcare workers. The cross-sectional analytical study was conducted between March 1 and 31, 2008, at a specialist tuberculosis hospital in Istanbul, Turkey, and comprised healthcare workers who had been employed for at least one year at the hospital and volunteered to take part. Tuberculin skin test and QuantiFERON-Tuberculosis Gold In-Tube test were both performed simultaneously and their results were compared Using SPSS 12. Out of 34 subjects, 20(58.8%) had a positive tuberculin skin test, and 7(20.6%) had a positive QuantiFERON-Tuberculosis Gold In-Tube test. The two tests agreed in only 15(44.1%) cases and disagreed in 19(55.9%). In 16(47.1%) subjects, the QuantiFERON-Tuberculosis Gold In-Tube test was negative and tuberculin skin testwas positive, while in 3(8.8%) participants QuantiFERON-Tuberculosis Gold In-Tube test was positive and tuberculin skin test was negative. Kappa test revealed discordance between the two tests (k=-0.13; p=0.92). Latent tuberculosis infection prevalence was higher based on tuberculin skin test than QuantiFERON-Tuberculosis Gold In-Tube test. The results of the two tests were discordant.

  4. The Tuberculin Skin Test versus QuantiFERON TB Gold (R) in Predicting Tuberculosis Disease in an Adolescent Cohort Study in South Africa

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    Mahomed, H.; Hawkridge, T.; Verver, S.; Abrahams, D.; Geiter, L.; Hatherill, M.; Ehrlich, R.; Hanekom, W.A.; Hussey, G.D.

    2011-01-01

    Setting: This study was conducted in a high tuberculosis (TB) burden area in Worcester, South Africa, with a notified all TB incidence rate of 1,400/100,000. Main Objective: To compare the predictive value of a baseline tuberculin skin test (TST) with that of the QuantiFERON TB Gold (In-tube) assay

  5. Comparison of Interferon gamma inducible protein-10 and Interferon gamma based QuantiFERON TB Gold assays with tuberculin skin test in HIV infected subjects

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    Basirudeen, S; Rajasekaran, S; Alamelu, R

    2011-01-01

    We aimed to compare the positivity of the QuantiFERON TB gold in-tube (QFT-IT antigens) specific Interferon gamma (IFN-γ/QFT-IT) and IFN-γ nducible protein-10 (IP-10/QFT-IT) assays with tuberculin skin test (TST) among human immunodeficiency virus (HIV) infected individuals in a TB endemic setting. A total of 180 HIV infected subjects, with no evidence of active TB were recruited. IFN-γ nd IP-10 levels specific to QFT-IT antigens were measured in plasma from QFT-IT tubes. The overall positivity of TST at 5mm cut-off point (19%) was significantly lower when compared to IFN-γ/QFT-IT (38%) and IP-10/QFT-IT (45%) assays. The positivity of IP-10/QFT-IT was significantly higher than IFN-γ/QFT-IT (p=0.038). Indeterminate results for IFN-γ/QFT-IT and IP-10/QFT-IT were more frequent in subjects with CD4 count 100 cells/µl. IFN-γ/QFT-IT (9%) yielded significantly higher number of indeterminate results than IP-10/QFT-IT (5%). The frequency of these responses is higher than the proportion of individuals with positive TST results. However, 6 IFN-γ/QFT-IT or IP-10/QFT-IT negative subjects were positive for TST at 5mm cut-off point. Prospective and prognostic studies are required to clarify the significance of these data. PMID:21996360

  6. [The utility of QuantiFERON TB Gold for diagnosing tuberculous meningitis in children].

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    Căliman-Sturdza, Olga Adriana; Mihalache, Doina; Luca, Catalina Mihaela; Petrovici, Cristina; Dorobăţ, Carmen Mihaela

    2010-01-01

    We performed QuantiFERON-TB Gold in Tube (QFT-G) in blood and CSF at 40 children diagnosed with TB meningitis and at 39 children with non TB meningitis, admitted between October 2006 and December 2009. The CSF analyses were suggestive for TB at 27 patients and only 14 had positive culture. The sensitivity of QFT-G in CSF was 72.72% and 69.44% in blood; specificity 96.96% in CSF and 89.18% in blood; the positive predictive value was 96% in CSF and 86.2% in blood; negative predictive value was 78.04% in CSF and 75% in blood. The sensitivity of TST was 61.76% and specificity 82.05%. The sensitivity of the culture from CSF was only 35%. The sensitivity and specificity of QFT-G was higher than TST and culture and better in CSF than in blood. The determination of alpha-interferon in serum and CSF is useful diagnostic marker of tuberculosis who could improve the management of TB meningitis.

  7. Prevalencia de tuberculosis latente mediante la realización de prueba de QuantiFERON TB Gold In Tube en una muestra de pacientes con cáncer de dos Hospitales Universitarios de Bogotá-Colombia, entre abril y octubre de 2015. Estudio de corte transversal

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    Callejas Gutiérrez, Ana Milena

    2015-01-01

    El presente estudio es un estudio de corte transversal que tiene como objetivo evaluar la prevalencia de tuberculosis latente mediante la realización de prueba de QuantiFERON – TB Gold In Tube en una muestra de pacientes con diagnóstico de cáncer de 2 hospitales de referencia de la ciudad de Santa Fé de Bogotá durante el período abril - octubre del 2015. El estudio se llevó a cabo con pacientes de la consulta de neumología de la Universidad Nacional de Colombia y en la Fundació...

  8. Performance of QuantiFERON TB Gold test in detecting latent tuberculosis infection in brain-dead organ donors in Iran: a brief report.

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    Tabarsi, Payam; Yousefzadeh, Amir; Najafizadeh, Katayoun; Droudinia, Atousa; Bayati, Rouzbeh; Marjani, Majid; Shafaghi, Shadi; Farokhzad, Banafsheh; Javanmard, Pedram; Velayati, Ali Akbar

    2014-11-01

    With regard to the significant morbidity and mortality due to tuberculosis in lung transplant recipients, the identification of brain-dead organ donors with latent tuberculosis by use of the QuantiFERON TB Gold (QFT-G) test may be of help to reduce the risk of TB reactivation and mortality in lung recipients. This study was conducted in the National Research Institute of Tuber-culosis and Lung Diseases (NRITLD) in Iran, from January to March 2013. A total of 38 conse-cutive brain-dead donors, not currently infected with active tuberculosis, were recruited. The medi-cal records of all the study enrollees were reviewed. A whole-blood IFN- release assay (IGRA) in reaction to early secreted antigenic target 6 (ESAT-6), culture filtrate protein 10 (CFP-10), and TB7.7 antigens, was performed and the released Interferon- was measured via enzyme-linked immunosorbent assay (ELISA). The data was analyzed with QFT-G software which was provided by the company. The demographic, characteristics and other variables were entered into SPSS version 11.5. The QFT-G test results of three donors (7.9%) turned out to be positive, negative for 24 donors (63.1%), and indeterminate for 11 cases (28.9%). Our study revealed the potential advantages of QFT-G in lowering the incidence of donor-derived post-transplant tuberculosis among lung recipients. However, a high rate of indeterminate results restricted the performance of QFT-G in this study.

  9. Performance of QuantiFERON TB Gold test in detecting latent tuberculosis infection in brain-dead organ donors in Iran: A brief report

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    Payam Tabarsi

    2014-01-01

    Full Text Available With regard to the significant morbidity and mortality due to tuberculosis in lung transplant recipients, the identification of brain-dead organ donors with latent tuberculosis by use of the QuantiFERON TB Gold (QFT-G test may be of help to reduce the risk of TB reactivation and mortality in lung recipients. This study was conducted in the National Research Institute of Tuber-culosis and Lung Diseases (NRITLD in Iran, from January to March 2013. A total of 38 conse-cutive brain-dead donors, not currently infected with active tuberculosis, were recruited. The medi-cal records of all the study enrollees were reviewed. A whole-blood IFN- release assay (IGRA in reaction to early secreted antigenic target 6 (ESAT-6, culture filtrate protein 10 (CFP-10, and TB7.7 antigens, was performed and the released Interferon- was measured via enzyme-linked immunosorbent assay (ELISA. The data was analyzed with QFT-G software which was provided by the company. The demographic, characteristics and other variables were entered into SPSS version 11.5. The QFT-G test results of three donors (7.9% turned out to be positive, negative for 24 donors (63.1%, and indeterminate for 11 cases (28.9%. Our study revealed the potential advantages of QFT-G in lowering the incidence of donor-derived post-transplant tuberculosis among lung recipients. However, a high rate of indeterminate results restricted the performance of QFT-G in this study.

  10. Performance of QuantiFERON TB gold test compared with the tuberculin skin test for detecting latent tuberculosis infection in lung and heart transplant candidates.

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    Mardani, Masoud; Farshidpour, Maham; Nekoonam, Mohsen; Varahram, Fatemeh; Najafizadeh, Katayoon; Mohammadi, Nazila; Sharifkashani, Babak; Gachkar, Latif; Farokhzad, Banafsheh; Droudinia, Atousa; Javanmard, Pedram; Tabarsi, Payam

    2014-04-01

    Evaluation for latent tuberculosis infection is advised before organ transplant. The interferon-gamma release assay has been shown to be more specific than the tuberculin skin test for screening for latent tuberculosis infection. We compared the tuberculin skin test and QuantiFERON-TB Gold In-Tube test for screening for latent tuberculosis infection and agreement between the tests in heart and lung transplant recipients before transplant. Fifty-five adult patients who had been evaluated for heart and lung transplant between September 2011 and September 2012 at Masih Daneshvari Hospital in Iran were prospectively enrolled. We performed the tuberculin skin test and QuantiFERON-TB Gold In-Tube test. Of the 55 patients, 3 (5%) had positive tuberculin skin test results, and 11 (20%) had positive QuantiFERON-TB Gold In-Tube test results. Agreement between the tuberculin skin test and QuantiFERON-TB Gold In-Tube test was fair (Kappa=0.061; 95% CI: - 0.185-0.307) (P = .56). The positivity for QuantiFERON-TB Gold In-Tube test was greater than the positivity for the tuberculin skin test, and QuantiFERON-TB Gold In-Tube test more accurately determined the risk for latent tuberculosis infection. However, a further longitudinal study is necessary to verify that the QFT-G test would predict developing tuberculosis after heart and lung transplant.

  11. Quantiferon-TB Gold: performance for ruling out active tuberculosis in HIV-infected adults with high CD4 count in Cote d'Ivoire, West Africa.

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    Christine Danel

    Full Text Available OBJECTIVE: To assess the performance of QuantiFERON-TB Gold In-Tube (QFT-GIT test for active tuberculosis (TB in HIV adults, and its variation over time in patients on antiretroviral therapy (ART and/or isoniazide preventive therapy (IPT. METHODS: Transversal study and cohort nested in the Temprano ANRS 12136 randomized controlled trial assessing benefits of initiating ART earlier than currently recommended by World Health Organization, with or without a 6-month IPT. Performance of QFT-GIT for detecting active TB at baseline in the first 50% participants, and 12-month incidence of conversion/reversion in the first 25% participants were assessed. QFT-GIT threshold for positivity was 0.35 IU/ml. RESULTS: Among the 975 first participants (median baseline CD4 count 383/mm3, positive QFT-GIT test 35%, 2.7% had active TB at baseline. QFT-GIT sensitivity, specificity, positive and negative predictive value for active TB were 88.0%, 66.6%, 6.5% and 99.5%. For the 444 patients with a second test at 12 months, rates for conversion and reversion were 9.3% and 14%. Reversion was more frequent in patients without ART and younger patients. IPT and early ART were not associated with reversion/conversion. CONCLUSION: A negative QFT-GIT could rule out active TB in HIV-infected adults not severely immunosuppressed, thus avoiding repeated TB testing and accelerating diagnosis and care for other diseases. TRIAL REGISTRATION: ClinicalTrials.gov NCT00495651.

  12. Clinical evaluation of QuantiFERON TB-2G test for immunocompromised patients.

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    Kobashi, Y; Mouri, K; Obase, Y; Fukuda, M; Miyashita, N; Oka, M

    2007-11-01

    The usefulness of the tuberculin skin test (TST) and the QuantiFERON TB-2G (QFT-TB) test were compared in immunocompromised patients. The subjects consisted of 252 immunocompromised patients who were clinically suspected of tuberculosis (TB) infection between April 2005 and December 2006. Regarding the underlying diseases, 74 subjects had malignant diseases, 72 were undergoing immunosuppressive treatment, 52 had diabetes mellitus, 50 had chronic renal failure and four had HIV infection. While the positive rate of the QFT-TB test for the diagnosis of TB infection (TB disease or latent TB infection) was 78.1%, that of TST for TB infection was 50.0%. The QFT-TB test was significantly better than TST. However, 32 (13%) patients had an indeterminate QFT-TB result. Indeterminate findings were significantly more frequent in patients receiving immunosuppressive treatment (28%), especially with lymphocytopaenia in the peripheral blood, than in those who had other underlying diseases. While TST-positive and QFT-TB test-negative results were recognised in immunocompromised patients with bacille Calmette-Guérin vaccination or nontuberculous mycobacterial disease, TST-negative and QFT-TB test-positive results were recognised in immunocompromised patients with a past history of TB infection. It was concluded that the QuantiFERON TB-2G test is a more useful diagnostic method for tuberculosis infection than tuberculin skin test for immunocompromised patients suspected of tuberculosis disease. However, because the results of the QuantiFERON TB-2G test show an indeterminate response for patients receiving immunosuppressive treatment, especially for those with lymphocytopaenia due to severe underlying diseases, care must be taken in the interpretation of the QuantiFERON TB-2G test for these patients.

  13. Diagnosis of latent tuberculosis infection before initiation of anti-tumor necrosis factor therapy using both tuberculin skin test and QuantiFERON-TB Gold In Tube assay.

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    Kim, Ho-Cheol; Jo, Kyung-Wook; Jung, Young Ju; Yoo, Bin; Lee, Chang-Keun; Kim, Yong-Gil; Yang, Suk-Kyun; Byeon, Jeong-Sik; Kim, Kyung-Jo; Ye, Byong Duk; Shim, Tae Sun

    2014-11-01

    Reactivation of latent tuberculosis infection (LTBI) is an important complication in patients treated with tumor necrosis factor-alpha (TNF-α) blocking agents. However, the best method for LTBI detection before initiation of anti-TNF therapy remains to be determined. From January 2010 to August 2013, anti-TNF therapy was initiated in 426 patients with immune-mediated inflammatory diseases (IMIDs). Tuberculin skin test (TST) and Quantiferon-TB Gold In Tube (QFT-GIT) assay were performed before starting anti-TNF treatment. LTBI was defined as a positive TST (induration ≥ 10 mm) or as a positive QFT-GIT result. Patients were followed up until December 2013. The positive TST and QFT-GIT rates were 22.3% (95/426) and 16.0% (68/426), respectively, yielding a total of 27.0% (115/426) of positive LTBI results. LTBI treatment was initiated in 25.1% (107/426) and was completed in 100% (107/107) of patients. During a median 294 days of follow-up, active TB occurred in 1.4% (6/426) of the patients with negative TST and QFT-GIT results at baseline. The either test positive strategy, using both TST and QFT-GIT assay, is acceptable for LTBI screening before commencing anti-TNF therapy in patients with IMIDs.

  14. Role of Quantiferon TB gold assays in monitoring the efficacy of antituberculosis therapy

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    N. Helmy

    2012-10-01

    Conclusion: The analysis of QFT-G assay results showed that in the majority of our TB patients there was a correlation between clinical treatment outcome and changes of IFN-γ response to M. tuberculosis-specific antigens.

  15. A toolbox for tuberculosis (TB diagnosis: an Indian multicentric study (2006-2008. Evaluation of QuantiFERON-TB gold in tube for TB diagnosis.

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    Philippe H Lagrange

    Full Text Available BACKGROUND: The aim of this multicentric prospective study in India was to assess the performance of the QuantiFERON TB-Gold in tube (QFT-GIT, Tuberculin Skin Test (TST and microbiological results as additional tools for diagnosing active tuberculosis (TB and latent infection (LTBI according to Human Immunodeficiency Virus (HIV status. METHODS: Individuals with and without active TB and HIV infection were enrolled between 2006-2008. QFT-GIT and TST results were analyzed per se and in combination with microbiological data. RESULTS: Among the 276 individuals (96 active pulmonary TB and 180 no active TB tested by QFT-GIT, 18 indeterminate results (6.5% were found, more significantly numerous in the HIV-infected (15/92; 16.3% than the HIV-uninfected (3/184; 1.6%(p<0.0001. QFT-GIT sensitivity for active TB was 82.3% and 92.9% respectively after including or excluding indeterminate results. Clinical sensitivity was significantly lower in the HIV-infected (68.4% than the HIV-uninfected (91.4% patients (p = 0.0059. LTBI was detected in 49.3% of subjects without active TB but varied according to TB exposure. When the TST and QFT-GIT were concomitantly performed, the respective sensitivity for active TB diagnosis was 95.0% and 85.0% in the HIV-uninfected (p = 0.60, and 66.7% and 51.5% in the HIV-infected patients (p = 0.32. QFT-GIT and TST respective specificity for active TB in the HIV-uninfected was 25.0% and 57.1% (p = 0.028, and 64.8% and 83.3% in the HIV-infected (p = 0.047. In those with active TB, QFT-GIT results were not associated with microbiological parameters (smear grade, liquid culture status, time-to-positivity of culture or clinical suspicion of active TB score (provided by the clinicians at enrollment. Combining microbiological tests with both immunological tests significantly increased sensitivity for active TB diagnosis (p = 0.0002, especially in the HIV-infected individuals (p = 0.0016. CONCLUSION: QFT

  16. Update on Immunological Test (Quantiferon-TB Gold) Contribution in the Management of Tuberculosis-Related Ocular Inflammation.

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    Trad, S; Bodaghi, B; Saadoun, D

    2017-07-12

    To clarify interferon-gamma release assay (IGRA) contributions to intraocular tuberculosis management, according to related TB endemic prevalence. Despite extensive investigations, including IGRA, the diagnosis of intraocular tuberculosis (TB) is still challenging and remains mostly presumptive. According to the literature, it appears that management of suspected ocular TB differs significantly based on whether patients are from areas of high TB prevalence or from non-TB-endemic countries. The accuracy and final contribution of chest X-rays, tuberculin skin test and IGRA differ significantly according to low or high endemic TB areas. This work aims to review IGRA test outcomes in the light of these clinical and epidemiological settings. We therefore focused our analysis and its subsequent guidelines proposal based on the TB prevalence where the patient lives. We believe that distinct guidelines should be determined for managing patients with suspected ocular TB, first taking into consideration the relative TB prevalence.

  17. Comparison of interferon-γ release assays, QuantiFERON TB-GIT and T-Spot.TB, in renal transplantation.

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    Ishikawa, Satoru; Igari, Hidetoshi; Akutsu, Naotake; Tsuyuzaki, Mizue; Aoyama, Hiromichi; Hasegawa, Masayuki; Otsuki, Kazunori; Maruyama, Michihiro; Saigo, Kenichi; Suzuki, Kiminori; Yamagishi, Fumio

    2017-07-01

    Renal transplant recipients are at increased risk of reactivating latent tuberculosis infection (LTBI) and progressing to active tuberculosis (TB). This study was conducted in National hospital for tuberculosis and renal transplantation (RT) in Japan. The purpose is to compare two interferon-γ release assays (IGRAs), QuantiFERON(®)-TB Gold in Tube (QFT) and T-SPOT(®).TB (TSPOT), in patients after renal transplantation for detecting latent TB infection (LTBI). Total 92 renal transplant recipients (median age 46 years, range 17-75) were prospectively enrolled, and QFT and TSPOT were concurrently examined. Total subjects were 92 patients (median age 46 years, range 17-75). The positive rate in QFT and TSPOT were 6.5% (95% confidence interval (CI) 3.0-13.5) and 2.2% (95% CI 1.0-7.6), respectively. There was a significant difference in IGRAs positivity (P TB during median follow-up of 994 days. Neither QFT nor TSPOT reaches estimated TB infection rate in Japan, especially elderly recipients aged 60 year-old or more. Therefore, both IGRAs might underestimate LTBI owing to immune suppressive therapy and aging. Physicians for renal transplantation need to understand the characteristics of both IGRAs and pay attention to the possibility of developing active TB even in patients of negative IGRAs results. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  18. QuantiFERON–TB Gold In-Tube test performance in Denmark

    DEFF Research Database (Denmark)

    Hermansen, Thomas; Lillebaek, Troels; Hansen, Ann-Brit E;

    2014-01-01

    BACKGROUND: Little is known about the QuantiFERON-TB Gold In-Tube Test (QFT) in extreme age groups. The test performance has been reported to be impaired in children and elderly, but reports are diverging. The aim of this study was to evaluate QFT performance in patients with and without Tubercul...... in children ≥ 1 years in low endemic regions but that the test should be used with care among the elderly.......BACKGROUND: Little is known about the QuantiFERON-TB Gold In-Tube Test (QFT) in extreme age groups. The test performance has been reported to be impaired in children and elderly, but reports are diverging. The aim of this study was to evaluate QFT performance in patients with and without...

  19. Within-Subject Interlaboratory Variability of QuantiFERON-TB Gold In-Tube Tests

    Science.gov (United States)

    2012-09-06

    Jaffar3,5¤c, Wanzer Drane7, David Maserang8¤d, Gerald H. Mazurek1 1 Division of Tuberculosis Elimination, Centers for Disease Control and Prevention, Atlanta...Georgia, United States of America, 2 Department of Medicine, Tripler Army Medical Center, Honolulu, Hawaii, United States of America, 3 Epidemiology ...QuantiFERONH-TB Gold In-Tube test (QFT-GIT) is a viable alternative to the tuberculin skin test (TST) for detecting Mycobacterium tuberculosis infection

  20. Quality control in QuantiFERON-TB gold in-tube for screening latent tuberculosis infection in health care workers.

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    Igari, Hidetoshi; Watanabe, Akira; Ichimura, Yasunori; Sakurai, Takayuki; Taniguchi, Toshibumi; Ishiwada, Naruhiko

    2017-04-01

    QuantiFERON-TB gold in-tube has been used for screening latent tuberculosis infection in newly employed health care workers in Japan. There have been a few studies concerning quality control. We retrospectively analysed QuantiFERON-TB gold in-tube results in a hospital in Japan. Interferon-γ values in three blood collection tubes for QuantiFERON-TB gold in-tube were analysed in association with the positivity rate. The data set consisted of health care workers aged 20-29 years during the 7 years between 2010 and 2016. The yearly QuantiFERON-TB gold in-tube positivity rate was 0.9%, 16.4%, 3.0%, 39.3%, 2.8%, 0.9% and 1.5%, and was extremely high in 2011 and 2013. The interferon-γ values in the tuberculosis antigen tube were elevated in these two years, as indicated by higher median and wider interquartile range. The interferon-γ value in the negative control tube was also higher in 2011. The higher interferon-γ values in collection tubes (tuberculosis antigen tube and/or negative control tube) resulted in higher QuantiFERON-TB gold in-tube positivity rate. The distribution of interferon-γ in tuberculosis antigen tube and negative control tube, as evaluated by median and interquartile range, proved to be an effective index for the quality control of QuantiFERON-TB gold in-tube. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  1. The impact of HIV infection and CD4 cell count on the performance of an interferon gamma release assay in patients with pulmonary tuberculosis

    DEFF Research Database (Denmark)

    Aabye, Martine G.; Ravn, Pernille; PrayGod, George;

    2009-01-01

    BACKGROUND: The performance of the tuberculosis specific Interferon Gamma Release Assays (IGRAs) has not been sufficiently documented in tuberculosis- and HIV-endemic settings. This study evaluated the sensitivity of the QuantiFERON TB-Gold In-Tube (QFT-IT) in patients with culture confirmed...

  2. The QuantiFERON-TB Gold In-Tube Assay in Neuro-Ophthalmology.

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    Little, Leanne M; Rigi, Mohammed; Suleiman, Ayman; Smith, Stacy V; Graviss, Edward A; Foroozan, Rod; Lee, Andrew G

    2017-09-01

    Although QuantiFERON-TB Gold In-Tube (QFT-GIT) testing is regularly used to detect infection with Mycobacterium tuberculosis, its utility in a patient population with a low risk for tuberculosis (TB) has been questioned. The following is a cohort study analyzing the efficacy of QFT-GIT testing as a method for detection of active TB disease in low-risk individuals in a neuro-ophthalmologic setting. Ninety-nine patients from 2 neuro-ophthalmology centers were identified as having undergone QFT-GIT testing between January 2012 and February 2016. Patients were divided into groups of negative, indeterminate, and positive QFT-GIT results. Records of patients with positive QFT-GIT results were reviewed for development of latent or active TB, as determined by clinical, bacteriologic, and/or radiographic evidence. Of the 99 cases reviewed, 18 patients had positive QFT-GIT tests. Of these 18 cases, 12 had documentation of chest radiographs or computed tomography which showed no evidence for either active TB or pulmonary latent TB infection (LTBI). Four had chest imaging which was indicative of possible LTBI. None of these 18 patients had symptoms of active TB and none developed active TB within the follow-up period. Based on our results, we conclude that routine testing with QFT-GIT in a low-risk cohort did not diagnose active TB infection. We do not recommend routine QFT-GIT testing for TB low-risk individuals, as discerned through patient and exposure history, ocular examination, and clinical judgment, in neuro-ophthalmology practice.

  3. Within-subject interlaboratory variability of QuantiFERON-TB gold in-tube tests.

    Directory of Open Access Journals (Sweden)

    William C Whitworth

    Full Text Available BACKGROUND: The QuantiFERON®-TB Gold In-Tube test (QFT-GIT is a viable alternative to the tuberculin skin test (TST for detecting Mycobacterium tuberculosis infection. However, within-subject variability may limit test utility. To assess variability, we compared results from the same subjects when QFT-GIT enzyme-linked immunosorbent assays (ELISAs were performed in different laboratories. METHODS: Subjects were recruited at two sites and blood was tested in three labs. Two labs used the same type of automated ELISA workstation, 8-point calibration curves, and electronic data transfer. The third lab used a different automated ELISA workstation, 4-point calibration curves, and manual data entry. Variability was assessed by interpretation agreement and comparison of interferon-γ (IFN-γ measurements. Data for subjects with discordant interpretations or discrepancies in TB Response >0.05 IU/mL were verified or corrected, and variability was reassessed using a reconciled dataset. RESULTS: Ninety-seven subjects had results from three labs. Eleven (11.3% had discordant interpretations and 72 (74.2% had discrepancies >0.05 IU/mL using unreconciled results. After correction of manual data entry errors for 9 subjects, and exclusion of 6 subjects due to methodological errors, 7 (7.7% subjects were discordant. Of these, 6 (85.7% had all TB Responses within 0.25 IU/mL of the manufacturer's recommended cutoff. Non-uniform error of measurement was observed, with greater variation in higher IFN-γ measurements. Within-subject standard deviation for TB Response was as high as 0.16 IU/mL, and limits of agreement ranged from -0.46 to 0.43 IU/mL for subjects with mean TB Response within 0.25 IU/mL of the cutoff. CONCLUSION: Greater interlaboratory variability was associated with manual data entry and higher IFN-γ measurements. Manual data entry should be avoided. Because variability in measuring TB Response may affect interpretation, especially near the cutoff

  4. QuantiFERON(R)-TB Gold In-Tube assay vs. tuberculin skin test in Indonesian children living with a tuberculosis case.

    NARCIS (Netherlands)

    Rutherford, M.E.; Nataprawira, M.; Yulita, I.; Apriani, L.; Maharani, W.; Crevel, R. van; Hill, P.C.; Alisjahbana, B.

    2012-01-01

    SETTING AND OBJECTIVES: The tuberculin skin test (TST) has limitations in diagnosing latent tuberculosis (TB) infection (LTBI). Interferon-gamma release assays may improve diagnostic accuracy. We compared QuantiFERON(R)-TB Gold In-Tube (QFT-GIT) and TST in Indonesian children. DESIGN: Children aged

  5. QuantiFERON®-TB gold in-tube performance for diagnosing active tuberculosis in children and adults in a high burden setting

    DEFF Research Database (Denmark)

    Rose, Michala Vaaben; Kimaro, Godfather; Nissen, Thomas N

    2012-01-01

    To determine whether QuantiFERON®-TB Gold In-Tube (QFT) can contribute to the diagnosis of active tuberculosis (TB) in children in a high-burden setting and to assess the performance of QFT and tuberculin skin test (TST) in a prospective cohort of TB suspect children compared to adults...

  6. Prevalence and risk factors of latent tuberculosis infection among health care workers in Malaysia

    OpenAIRE

    Rampal Krishna; Rafiza Shaharudin; Tahir Aris

    2011-01-01

    Abstract Background Health care workers are exposed to patients with tuberculosis and are at risk of nosocomial infection. The aim of this study was to determine the prevalence and factors associated with latent tuberculosis infection among health care workers in Malaysia and also to evaluate the agreement between Quantiferon TB Gold in tube test with Tuberculin Skin Test. Methods A cross sectional study was conducted at four randomly selected hospitals in the Klang Valley from December 2008 ...

  7. [Tuberculosis screening program for undocumented immigrant teenagers using the QuantiFERON(®)-TB Gold In-Tube test].

    Science.gov (United States)

    Salinas, Carlos; Ballaz, Aitor; Díez, Rosa; Aguirre, Urko; Antón, Ane; Altube, Lander

    2015-07-06

    The aim of this study was to determine the prevalence of tuberculosis infection in undocumented immigrant teenagers using a tuberculin skin test (TST) for initial screening and QuantiFERON(®)-TB Gold In-Tube (QFT-GIT) as a confirmatory test. From 2007 to 2012, under 19 year-old immigrant teenagers from 2 accommodation centers of the Basque Country (Spain) were included in the study. The TST was done in all of them and the QFT-GIT was done in selected patients with a TST≥5mm. Eight hundred and forty-five immigrants were included, most of them from Africa (99.5%). Fifty-one percent of immigrants with TST ≥ 5 mm has a positive QFT-GIT. We found 2 cases of active tuberculosis (2/845: 0.24%). The concordance between TST (≥ 10 mm) and QFT-GIT was 63%, with 57% of positive concordance cases and 96% of negative concordances. There were 246 cases with TST ≥ 10 mm (29%), with significant differences between Magrebis (21.5%) and Subsaharians (67%) (Pimmigrants, we recommend implementing screening programs in this population. Using QFT-GIT, the number of candidates for chemoprophylaxis was reduced to 43% compared with TST alone (≥ 10 mm). Copyright © 2013 Elsevier España, S.L.U. All rights reserved.

  8. QuantiFERON®-TB Gold In-Tube for contact screening in BCG-vaccinated adults: A longitudinal cohort study.

    Science.gov (United States)

    Muñoz, Laura; Gonzalez, Lucia; Soldevila, Laura; Dorca, Jordi; Alcaide, Fernando; Santin, Miguel

    2017-01-01

    To assess the utility of QuantiFERON®-TB Gold In-tube (QFT-GIT) for targeting preventive therapy in BCG-vaccinated contacts of tuberculosis (TB), based on its high specificity and negative predictive value for development of TB. We compared two screening strategies for TB contact tracing in two consecutive periods: the tuberculin skin test (TST) period, when all contacts were screened with the TST alone; and the QFT-GIT period, when BCG-vaccinated contacts underwent TST and QFT-GIT. Diagnosis of TB infection among BCG-vaccinated contacts relied on TST ≥5 mm in the TST period, while in the QFT-GIT period either a positive QFT-GIT or a TST ≥15 mm was required. Six hundred and sixty-one contacts were compared. In the QFT-GIT period there was a reduction in diagnoses of TB infection (77.4% vs. 51.2%; p TB were 0.62 and 0.29 in the TST and QFT-GIT periods respectively (p = 0.59). In BCG-vaccinated TB contacts, the addition of QFT-GIT safely reduced TB diagnosis and treatment rates without increasing the risk of subsequent active TB.

  9. Serial testing for latent tuberculosis using QuantiFERON-TB Gold In-Tube: A Markov model

    Science.gov (United States)

    Moses, Mark W.; Zwerling, Alice; Cattamanchi, Adithya; Denkinger, Claudia M.; Banaei, Niaz; Kik, Sandra V.; Metcalfe, John; Pai, Madhukar; Dowdy, David

    2016-01-01

    Healthcare workers (HCWs) in low-incidence settings are often serially tested for latent TB infection (LTBI) with the QuantiFERON-TB Gold In-Tube (QFT) assay, which exhibits frequent conversions and reversions. The clinical impact of such variability on serial testing remains unknown. We used a microsimulation Markov model that accounts for major sources of variability to project diagnostic outcomes in a simulated North American HCW cohort. Serial testing using a single QFT with the recommended conversion cutoff (IFN-g > 0.35 IU/mL) resulted in 24.6% (95% uncertainty range, UR: 23.8–25.5) of the entire population testing false-positive over ten years. Raising the cutoff to >1.0 IU/mL or confirming initial positive results with a (presumed independent) second test reduced this false-positive percentage to 2.3% (95%UR: 2.0–2.6%) or 4.1% (95%UR: 3.7–4.5%), but also reduced the proportion of true incident infections detected within the first year of infection from 76.5% (95%UR: 66.3–84.6%) to 54.8% (95%UR: 44.6–64.5%) or 61.5% (95%UR: 51.6–70.9%), respectively. Serial QFT testing of HCWs in North America may result in tremendous over-diagnosis and over-treatment of LTBI, with nearly thirty false-positives for every true infection diagnosed. Using higher cutoffs for conversion or confirmatory tests (for initial positives) can mitigate these effects, but will also diagnose fewer true infections. PMID:27469388

  10. Prevalence and risk factors of latent tuberculosis infection among health care workers in Malaysia

    Directory of Open Access Journals (Sweden)

    Rampal Krishna

    2011-01-01

    Full Text Available Abstract Background Health care workers are exposed to patients with tuberculosis and are at risk of nosocomial infection. The aim of this study was to determine the prevalence and factors associated with latent tuberculosis infection among health care workers in Malaysia and also to evaluate the agreement between Quantiferon TB Gold in tube test with Tuberculin Skin Test. Methods A cross sectional study was conducted at four randomly selected hospitals in the Klang Valley from December 2008 to May 2009. Self administered questionnaire was used to obtain information on health care workers and possible risk factors. The response rate for this study was 90.8% with 954 respondents completed the questionnaire and were tested with Quantiferon TB Gold in tube for latent tuberculosis infection. Agreement between Quantiferon TB Gold in tube and Tuberculin Skin Test was assessed among 95 health care workers who consented to undergo both tests. Results The overall prevalence of latent tuberculosis infection among health care workers was 10.6% (CI: 8.6%; 12.6%. Factors significantly associated with latent tuberculosis infection were aged 35 years and older [9.49 (CI: 2.22; 40.50], history of living in the same house with close family members or friends who had active tuberculosis [8.69 (CI: 3.00; 25.18], worked as a nurse [4.65 (CI: 1.10; 19.65] and being male [3.70 (CI: 1.36; 10.02]. Agreement between Quantiferon TB Gold in tube test and tuberculin skin test at cut-off points of 10 mm and 15 mm was 50.5% and 82.1% respectively. However, Kappa-agreement was poor for both cut-off points. Conclusion The prevalence of latent tuberculosis infection in Malaysia was relatively low for an intermediate TB burden country. We could not comment on the occupational risk of latent tuberculosis infection among health care worker compared to the general population as there were no prevalence data available for latent tuberculosis infection in the general population

  11. Comparison of tuberculin skin test and QuantiFERON®-TB Gold In-Tube for the diagnosis of childhood tuberculosis.

    Science.gov (United States)

    Uzunhan, Ozan; Törün, Selda Hançerli; Somer, Ayper; Salman, Nuran; Köksalan, Kaya

    2015-10-01

    Tuberculosis (TB) is an important worldwide ongoing health issue. To be able to control TB, one should not only cure active TB but also identify childhood TB patients who have the possibility to develop active disease in the future. The aim of this study was to compare a century-old tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube (QFT-GIT) test, developed as an alternative to TST and which has been claimed to be superior to TST in several ways, in the diagnosis of childhood TB. Fifty-three children with TB between 5 months and 17.5 years of age and 92 healthy children from the same age group with no risk factors for TB were recruited into the study. All children underwent TST and QFT-GIT test and their demographic, clinic and laboratory data were recorded. Data were analyzed using SPSS 14. A total of 53 patients were diagnosed with TB. Mean patient age was 8.5 ± 4.3 years (range, 5 months-17.5 years). A total of 41.7% of the patients were female. Sixteen of 53 patients had confirmation on culture. QFT-GIT test was positive in 16 and TST was positive in 15 among 16 children with culture-confirmed TB. The sensitivity of TST and QFT-GIT were 93.8% and 100.0%, and the specificity of TST and QFT-GIT were 100.0% and 97.8%, respectively. With regard to the 53 TB children including those without bacteriological confirmation, QFT-GIT was positive in 33 children, and TST was positive in 44 children. The sensitivity of TST and QFT-GIT was then 83.0% and 62.3%, and the specificity, 100.0% and 97.8%, respectively. Although positive QFT-GIT test is very significant for TB, negative results will not exclude TB infection. TST and QFT-GIT used together may provide more efficient results. © 2015 Japan Pediatric Society.

  12. Accuracy of the QuantiFERON-TB Gold in Tube for diagnosing tuberculosis in a young pediatric population previously vaccinated with Bacille Calmette-Guerin

    Directory of Open Access Journals (Sweden)

    Marcelo Genofre Vallada

    2014-03-01

    Full Text Available Objective: To evaluate the accuracy of an interferongamma release assay (QuantiFERON-TB Gold in Tube for diagnosing Mycobacterium tuberculosis infection in a young pediatric population. Methods: 195 children previously vaccinated with BCG were evaluated, being 184 healthy individuals with no clinical or epidemiological evidence of mycobacterial infection, and 11 with Mycobacterium tuberculosis infection, according to clinical, radiological, and laboratory parameters. A blood sample was obtained from each child and processed according to the manufacturer's instructions. The assay performance was evaluated by a Receiver Operating Characteristic (ROC curve. Results: In the group of 184 non-infected children, 130 (70.6% were under the age of four years (mean age of 35 months. In this group, 177 children (96.2% had negative test results, six (3.2% had indeterminate results, and one (0.5% had a positive result. In the group of 11 infected children, the mean age was 58.5 months, and two of them (18% had negative results. The ROC curve had an area under the curve of 0.88 (95%CI 0.82-0.92; p<0.001, disclosing a predictive positive value of 81.8% for the test (95%CI 46.3-97.4. The assay sensitivity was 81.8% (95%CI 48.2-97.2 and the specificity was 98.8% (95%CI 96-99.8. Conclusions: In the present study, the QuantiFERON-TB Gold in Tube performance for diagnosing M. tuberculosis infection was appropriate in a young pediatric population.

  13. Kinetics of the QuantiFERON-TB Gold In-Tube test during treatment of patients with sputum smear-positive tuberculosis in relation to initial TST result and severity of disease

    DEFF Research Database (Denmark)

    Idh, Jonna; Abate, Ebba; Westman, Anna

    2010-01-01

    The QuantiFERON-TB Gold In-Tube test (QFN) measures interferon-gamma production in response to Mycobacterium tuberculosis antigens. Our aim was to assess the kinetics of the QFN and initial tuberculin skin test (TST) result in relation to severity of disease in a tuberculosis (TB) endemic area...

  14. Tuberculin Skin Test and QuantiFERON(®)-TB Gold In-Tube Test for Diagnosing Latent Tuberculosis Infection among Thai Healthcare Workers.

    Science.gov (United States)

    Khawcharoenporn, Thana; Apisarnthanarak, Anucha; Sangkitporn, Somchai; Rudeeaneksin, Janisara; Srisungngam, Sopa; Bunchoo, Supranee; Phetsuksiri, Benjawan

    2016-05-20

    A cross-sectional study was conducted on the performance of the tuberculin skin test (TST) and QuantiFERON(®)-TB Gold In-Tube test (QFT-IT) for detecting latent tuberculosis infection among Thai healthcare workers (HCWs). Each HCW underwent both the TST and QFT-IT during the annual health screening. Among the 260 HCWs enrolled, the median age was 30 years (range 19-60 years), 92% were women, 64% were nurses and nurse assistants, 78% were Bacillus Calmette Guérin vaccinated, and 37% had previously taken the TST. Correlation between TST reaction size and the interferon-γ level was weak (r = 0.29; P tuberculosis diagnosis, the cut-off for TST reactivity with the best performance was ≥13 mm with a sensitivity, specificity, false positivity, and false negativity of 71%, 70%, 30%, and 29%, respectively (area under the curve 0.73; P < 0.001). The independent factor associated with a false reactive TST was a previous TST (adjusted odds ratio 1.83; P = 0.04). Our findings suggest that the QFT-IT may be the preferred test among HCWs with previous TST. In settings where the QFT-IT is not available, appropriate cut-offs for TST reactivity should be evaluated for use among HCWs.

  15. Assessing the Prevalence of Latent Tuberculosis among Health Care Providers in Zagazig City, Egypt Using Tuberculin Skin Test and QuantiFERON-TB Gold In-Tube Test.

    Science.gov (United States)

    El-Sokkary, Rehab H; Abu-Taleb, Ashwak M; El-Seifi, Omnia S; Zidan, Haidy E; Mortada, Eman M; El-Hossary, Dalia; Farag, Salama E

    2015-12-01

    Early detection of latent tuberculosis infection (LTBI) will prevent development of active TB among health care providers. The aim of the study was to assess the prevalence of LTBI among health care providers and compare the QuantiFERON-TB Gold In-Tube Test (QFT-GIT) and Tuberculin skin test in efforts to detect LTBI and to investigate possible associated risk factors of infection. A cross sectional study was carried out during the period of 6 months in the Chest Hospital in Zagazig city and the Nephrology Unit at Zagazig University Hospitals in 132 randomly selected health care providers who were examined for LTBI by QFT-GIT and Tuberculin skin test and for the associated risk factors as well. The prevalence of LTBI identified by QFT-GIT and by Tuberculin skin test was 28.8% and 59.1%, respectively. Poor agreement was observed between the two tests (kappa=0.10). Working more than 10 years, being nurse, diabetic and smoker were risk factors significantly associated with LTBI (p<0.05). QFT-GIT is considered a useful tool in detecting LTBI cases, especially in a country where BCG vaccination is a national policy (as in Egypt). Duration of work, profession, diabetes and smoking are the risk factors for LTBI. Active surveillance and infection control measures are recommended to reduce the risk of LTBI. Copyright© by the National Institute of Public Health, Prague 2015.

  16. The impact of HIV infection and CD4 cell count on the performance of an interferon gamma release assay in patients with pulmonary tuberculosis

    DEFF Research Database (Denmark)

    Aabye, Martine G.; Ravn, Pernille; PrayGod, George

    2009-01-01

    BACKGROUND: The performance of the tuberculosis specific Interferon Gamma Release Assays (IGRAs) has not been sufficiently documented in tuberculosis- and HIV-endemic settings. This study evaluated the sensitivity of the QuantiFERON TB-Gold In-Tube (QFT-IT) in patients with culture confirmed...... pulmonary tuberculosis (PTB) in a TB- and HIV-endemic population and the effect of HIV-infection and CD4 cell count on test performance. METHODOLOGY/PRINCIPAL FINDINGS: 161 patients with sputum culture confirmed PTB were subjected to HIV- and QFT-IT testing and measurement of CD4 cell count. The QFT...

  17. Interferon gamma release assays for the diagnosis of latent TB infection in HIV-infected individuals in a low TB burden country.

    LENUS (Irish Health Repository)

    Cheallaigh, Clíona Ní

    2013-01-01

    Interferon gamma release assays (IGRAs) are used to diagnose latent tuberculosis infection. Two IGRAs are commercially available: the Quantiferon TB Gold In Tube (QFT-IT) and the T-SPOT.TB. There is debate as to which test to use in HIV+ individuals. Previous publications from high TB burden countries have raised concerns that the sensitivity of the QFT-IT assay, but not the T-SPOT.TB, may be impaired in HIV+ individuals with low CD4+ T-cell counts. We sought to compare the tests in a low TB burden setting.

  18. QuantiFERON-TB Gold In-Tube assay for screening arthritis patients for latent tuberculosis infection before starting anti-tumor necrosis factor treatment.

    Directory of Open Access Journals (Sweden)

    Hyun Lee

    Full Text Available Patients undergoing anti-tumor necrosis factor (TNF treatment are at an increased risk of reactivating a latent tuberculosis infection (LTBI. This study evaluated the effectiveness of the QuantiFERON-TB Gold In-Tube (QFT assay for diagnosing LTBI in arthritis patients undergoing anti-TNF treatment.We enrolled 342 consecutive patients from August 2007 to October 2013: 176 (51.5% patients with ankylosing spondylitis and 166 (48.5% with rheumatoid arthritis. Screening tests included tuberculin skin test (TST and QFT assay. Positive QFT results, regardless of TST results, were considered an indicator for LTBI treatment.Bacillus Calmette-Guérin scars were found in 236 (69.0% patients. Of 342 patients, TST and QFT were positive in 122 (35.7% and 103 (30.1% patients, respectively, and discordant in 101 (29.5% patients. During a median follow-up duration of 41.7 months, five patients (1.5% developed TB in a median of 20.8 months after initiation of anti-TNF treatment (428/100,000 person-years. TB did not occur in 62 TST+/QFT+ patients who received LTBI treatment. Of 41 TST-/QFT+ patients who received LTBI treatment, one (2.4% developed TB 20.5 months after starting anti-TNF treatment (705/100,000 person-years. Of 60 TST+/QFT- patients who did not receive LTBI treatment, two (3.3% developed TB 20.8 and 22.0 months after starting anti-TNF treatment (871/100,000 person-years. Of 179 TST-/QFT- patients, two (1.1% developed TB 7.2 and 22.7 months, respectively, after initiating anti-TNF treatment (341/100,000 person-years. TB incidence rate during the follow-up period did not differ among TST-/QFT+, TST+/QFT-, and TST-/QFT- patients (P = 0.661.QFT might be used instead of TST for diagnosing LTBI in patients before starting anti-TNF therapy in countries, such as Korea, where the TB prevalence is intermediate and the BCG vaccination is mandatory at birth. In the absence of a true gold standard test for LTBI, however, there is still a risk of TB development

  19. Cost analysis of tuberculin skin test and the QuantiFERON-TB Gold In-tube test for tuberculosis screening in a correctional setting in Dallas, Texas, USA.

    Science.gov (United States)

    Nijhawan, Ank E; Iroh, Princess A; Brown, Larry S; Winetsky, Daniel; Porsa, Esmaeil

    2016-10-12

    Tuberculosis (TB) disproportionately affects immigrants, HIV-infected individuals, and those living in crowded settings such as homeless shelters and correctional facilities. Although the majority of jails and prisons use a tuberculin skin test (TST) for latent tuberculosis infection (LTBI) screening, limited data exist on the clinical performance and costs of the TST compared to interferon gamma release assays (IGRAs) in this setting. A prospective pilot study comparing cost between TST and an IGRA (QuantiFERON Gold In-tube, QFT-GIT) for the detection of LTBI in a convenience sample of inmates entering the Dallas County Jail (DCJ) was conducted June-October 2014. Participants completed a risk questionnaire, TST placement, QFT-GIT testing, and were offered opt-out HIV-Ab testing. LTBI prevalence based on TST and QFT-GIT results, an evaluation of discordant results and a cost analysis are presented. A total of 529 subjects were enrolled. The majority were male (75 %), and 46 % were Black, 29 % White, and 24 % Hispanic. Most (85 %) had been previously incarcerated. Over 28 % of participants were released prior to TST reading, with paired QFT-GIT and TST results available for 351 subjects. Of these, nine (2.6 %) tested positive by TST and 47 (13.4 %) tested positive by QFT-GIT. It costs $23.27 more per inmate per year to screen with QFT-GIT than TST in this population, though the cost per LTBI case detected was nearly three times higher for TST than QFT-GIT ($1247 v $460). We found a substantially higher rate of QFT-GIT positivity compared to TST in this sample of individuals entering the Dallas County Jail. Although no gold standard exists, this finding may indicate under-recognized LTBI in this setting. QFT-GIT as an initial screening tool was more time-efficient, had four-fold fewer labor costs and provided results on more individuals when compared with the TST. The overall cost of QFT-GIT was $23.27 more per inmate per year, though the cost per LTBI case

  20. A combination of the QuantiFERON-TB Gold In-Tube assay and the detection of adenosine deaminase improves the diagnosis of tuberculous pleural effusion.

    Science.gov (United States)

    Liu, Yuanyuan; Ou, Qinfang; Zheng, Jian; Shen, Lei; Zhang, Bingyan; Weng, Xinhua; Shao, Lingyun; Gao, Yan; Zhang, Wenhong

    2016-08-03

    The differential diagnosis of tuberculous pleural effusion (TPE) and malignant pleural effusion (MPE) remains difficult despite the availability of numerous diagnostic tools. The current study aimed to evaluate the performance of the whole blood QuantiFERON-TB Gold In-Tube (QFT-GIT) assay and conventional laboratory biomarkers in differential diagnosis of TPE and MPE in high tuberculosis prevalence areas. A total of 117 patients with pleural effusions were recruited, including 91 with TPE and 26 with MPE. All of the patients were tested with QFT-GIT, and the conventional biomarkers in both blood and pleural effusion were detected. The level of antigen-stimulated QFT-GIT in the whole blood of TPE patients was significantly higher than that of MPE (2.89 vs 0.33 IU/mL, Pdiagnosis of TPE were 93.0% and 60.0%, respectively. Among the biomarkers in blood and pleural effusion, pleural adenosine deaminase (ADA) was the most prominent biomarker, with a cutoff value of 15.35 IU/L. The sensitivity and specificity for the diagnosis of TPE were 93.4% and 96.2%, respectively. The diagnostic classification tree from the combination of these two biomarkers was 97.8% sensitive and 92.3% specific. Ultimately, the combination of whole blood QFT-GIT with pleural ADA improved both the specificity and positive predictive value to 100%. Thus, QFT-GIT is not superior to pleural ADA in the differential diagnosis of TPE and MPE. Combined whole blood QFT-GIT and pleural ADA detection can improve the diagnosis of TPE.

  1. Factors that Predict Negative Results of QuantiFERON-TB Gold In-Tube Test in Patients with Culture-Confirmed Tuberculosis: A Multicenter Retrospective Cohort Study.

    Directory of Open Access Journals (Sweden)

    Yong-Soo Kwon

    Full Text Available Interferon-γ release assays such as the QuantiFERON-TB Gold In-Tube Test (QFT-GIT are designed to detect Mycobacterium tuberculosis infections, whether latent or manifesting as disease. However, a substantial number of persons with culture-confirmed tuberculosis (TB have negative QFT-GITs. Information on host factors contributing to false-negative and indeterminate results are limited.A multicenter retrospective cohort study was performed with 1,264 culture-confirmed TB patients older than 18 years who were subjected to the QFT-GIT at one of the six hospitals between May 2007 and February 2014. Patients with human immunodeficiency virus infection were excluded. Clinical and laboratory data were collected in South Korea.Of all patients, 87.6% (1,107/1,264 were diagnosed with pulmonary TB and 12.4% (157/1,264 with extrapulmonary TB. The rate of negative results was 14.4% (182/1,264. The following factors were highly correlated with false-negative results in the QFT-GIT: advanced age (age ≥ 65 years, odds ratio [OR] 1.57, 95% confidence interval [CI] 1.03-2.39, bilateral disease as determined by chest radiography (OR 1.75, 95% CI 1.13-2.72, malignancy (OR 2.42, 95% CI 1.30-4.49, and lymphocytopenia (total lymphocyte count < 1.0 × 109/L, OR 1.86, 95% CI 1.21-2.87.Consequently, QFT-GIT results need to be interpreted with caution in patients with these host risk factors such as the elderly, bilateral disease on chest radiography, or malignancy, or lymphocytopenia.

  2. Tuberculin skin test and QuantiFERON-TB Gold In-tube Test for latent tuberculosis in Thai HIV-infected adults.

    Science.gov (United States)

    Khawcharoenporn, Thana; Apisarnthanarak, Anucha; Phetsuksiri, Benjawan; Rudeeaneksin, Janisara; Srisungngam, Sopa; Mundy, Linda M

    2015-02-01

    Limited data exist for the performance of QuantiFERON-TB Gold In-tube Test (QFT-IT) in comparison to tuberculin skin test (TST) for detecting latent tuberculosis (LTB) in patients with human immunodeficiency virus (HIV) infection from tuberculosis (TB)-endemic Asia-Pacific countries. A cohort study of Thai HIV-infected patients without history of TB or LTB treatment was conducted from March 2012 through March 2013. Each patient underwent simultaneous TST and QFT-IT. Among the 150 enrolled subjects, the median age was 40 years (range 17-65), 53% were male, and the median CD4 count was 367 cells/μL (range 8-1290). Reactive TST and positive QFT-IT were 16% and 13%, respectively, with low concordance between tests (kappa = 0.26); correlation between TST reaction size and level of interferon-γ was moderate (r = 0.34). Independent factors associated with discordant results were long-term smoking (adjusted odds ratio (aOR) 5.74; P = 0.002) for TST-reactive, QFT-IT-negative subjects, and age greater than 52 years (aOR 5.56; P = 0.02) and female gender (aOR 4.40; P = 0.04) for TST non-reactive, QFT-IT-positive subjects. The level of agreement between both tests improved when using a TST cut-off of ≥ 10 mm (kappa = 0.39). In our setting where QFT-IT is available but has limited use due to cost, TST with a cut-off of 10 mm for reactivity should be the initial LTB test. HIV-infected women and persons older than 52 years with non-reactive TST and long-term smokers with reactive TST may benefit from subsequent QFT-IT. © 2014 Asian Pacific Society of Respirology.

  3. Evaluation of the QuantiFERON?-TB Gold In-Tube assay and tuberculin skin test for the diagnosis of Mycobacterium tuberculosis infection in northeastern Thailand.

    Science.gov (United States)

    Reechaipichitkul, Wipa; Pimrin, Wilailuk; Bourpoern, Janpen; Prompinij, Supapim; Faksri, Kiatichai

    2015-09-01

    The diagnosis of latent Mycobacterium tuberculosis infection (LTBI) is currently based on the immunological response of T-cells to M. tuberculosis (MTB) antigens. However, the QuantiFERON®-TB Gold In-Tube assay (QFT) has not yet been evaluated in the Thai adult population. To evaluate the diagnostic performance and determine predictors of discordant results between the QFT and tuberculin skin test (TST). Active tuberculosis (ATB) patients (n=54), close contacts (CCs) living in the same household as a TB patient (n=100) and healthy controls (HCs) (n=60) were interviewed and underwent the QFT and TST at Srinagarind Hospital in Thailand. Various cut-off values for the QFT (0.25-0.35 IU/mL) and TST (5-15 mm) were applied. The maximum agreement rate between the tests was 71.5% (κ=0.41) with cut-offs of 0.35 IU/mL and 10 mm or 0.25 IU/mL and 10 mm. Based on standard cut-off values (0.35 IU/mL and 10 mm) and using ATB patients and HCs as positive and negative controls, the TST was more sensitive than the QFT (87.0% vs. 66.7%, respectively), whereas the QFT was more specific than the TST (83.3% vs. 70.0%, respectively). Being underweight (OR 3.86, 95%CI 1.3-11.48) or overweight (OR 5.9, 95%CI 1.24-28.16) was significantly associated with TST+/QFT- results. Diabetes (OR 32.56, 95%CI 1.73-613.49) and poor or fair nutrition (OR 7.4, 95%CI 1.23-44.57) were significantly associated with TST-/QFT+ results. The TST should be used as a screening test based on its higher sensitivity, whereas the QFT should be used as a confirmatory test because of its higher specificity.

  4. Effect of micronutrient deficiency on QuantiFERON-TB Gold In-Tube test and tuberculin skin test in diagnosis of childhood intrathoracic tuberculosis.

    Science.gov (United States)

    Mukherjee, A; Saini, S; Kabra, S K; Gupta, N; Singh, V; Singh, S; Bhatnagar, S; Saini, D; Grewal, H M S; Lodha, R

    2014-01-01

    Data on performance of QuantiFERON-TB Gold In-Tube test (QFT) and tuberculin skin test (TST) in children with active tuberculosis from high burden countries in the context of micronutrient deficiency are scarce. The objective of this study was to evaluate the effect of micronutrient deficiency on the performance of TST and QFT in children with intrathoracic tuberculosis. Children with probable intrathoracic tuberculosis underwent TST, QFT, gastric lavages and induced sputum examination for AFB (Acid-Fast Bacilli) smear and culture. Zinc, copper, ferritin and vitamin D were measured on stored serum samples. The study used cross-sectional data at initiation of anti-tubercular therapy. Three hundred and sixty-two children (median age 115.5 months (interquartile range: 73, 144), 200 (55.3%) girls) were enrolled in the study. Microbiological confirmation of tuberculosis could be obtained in 128 patients. TST and QFT were positive in 337 (93%) and 297 (82%) children, respectively. Performance of both the tests was unaffected by weight-for-age and height-for-age 'z-scores' or by serum copper levels. TST was not affected by serum zinc and ferritin levels. Children with negative QFT results had lower mean serum zinc level (P=0.01) and higher ferritin levels (P=0.007) as compared to those with positive test. Higher proportion of children with positive TST were vitamin D deficient/insufficient (P=0.003). Micronutrient status, especially serum levels of zinc, may influence the performance of QFT in children with intrathoracic tuberculosis. Considering the high prevalence of zinc deficiency in developing countries, QFT should be used cautiously for diagnosing tuberculosis.

  5. Predictive value of the tuberculin skin test and QuantiFERON-tuberculosis Gold In-Tube test for development of active tuberculosis in hemodialysis patients

    Science.gov (United States)

    Seyhan, Ekrem Cengiz; Gunluoglu, Gulşah; Gunluoglu, Mehmet Zeki; Tural, Seda; Sökücü, Sinem

    2016-01-01

    BACKGROUND: Hemodialysis (HD) patients are at increased risk of reactivation of latent tuberculosis infection (LTBI) compared with the general population. QuantiFERON-TB Gold (QFT-G) for LTBI detection is more promising than tuberculin skin test (TST) in HD patients. AIM: In our study, we evaluated the value of the TST and QFT-G In-Tube (QFG-IT) test in the development of active tuberculosis (TB), in the HD patients, and in healthy controls. METHODS: The study enrolled 95 HD patients and ninety age-matched, healthy controls. The TST and QFG-IT were performed. All the subjects were followed up 5 years for active TB disease. RESULTS: Compared to the healthy controls, a high prevalence of LTBI was found in the HD patients by QFG-IT (41% vs. 25%). However, no significant difference was detected by TST (32% vs. 31%). Four HD patients and one healthy control progressed to active TB disease within the 5-year follow-up. For active TB discovered subjects, QFG-IT was positive in all, but TST was positive in two (one patient and one healthy control). In HD patients; sensitivity, specificity, positive and negative predictive values of QFG-IT, and TST for active TB was 100% and 25%, 62% and 67%, 10%, and 3%, and 100% and 95%, respectively. Receiver operating curve analysis revealed that the results are significantly different (P = 0.04). CONCLUSION: QFG-IT test is a more useful diagnostic method than TST for detecting those who will progress to active TB in HD patients. PMID:27168859

  6. QuantiFERON®-TB gold in-tube performance for diagnosing active tuberculosis in children and adults in a high burden setting.

    Directory of Open Access Journals (Sweden)

    Michala V Rose

    Full Text Available AIM: To determine whether QuantiFERON®-TB Gold In-Tube (QFT can contribute to the diagnosis of active tuberculosis (TB in children in a high-burden setting and to assess the performance of QFT and tuberculin skin test (TST in a prospective cohort of TB suspect children compared to adults with confirmed TB in Tanzania. METHODS: Sensitivity and specificity of QFT and TST for diagnosing active TB as well as indeterminate QFT rates and IFN-γ levels were assessed in 211 TB suspect children in a Tanzanian district hospital and contrasted in 90 adults with confirmed pulmonary TB. RESULTS: Sensitivity of QFT and TST in children with confirmed TB was 19% (5/27 and 6% (2/31 respectively. In adults sensitivity of QFT and TST was 84% (73/87 and 85% (63/74. The QFT indeterminate rate in children and adults was 27% and 3%. Median levels of IFN-γ were lower in children than adults, particularly children <2 years and HIV infected. An indeterminate result was associated with age <2 years but not malnutrition or HIV status. Overall childhood mortality was 19% and associated with an indeterminate QFT result at baseline. CONCLUSION: QFT and TST showed poor performance and a surprisingly low sensitivity in children. In contrast the performance in Tanzanian adults was good and comparable to performance in high-income countries. Indeterminate results in children were associated with young age and increased mortality. Neither test can be recommended for diagnosing active TB in children with immature or impaired immunity in a high-burden setting.

  7. Agreement between QuantiFERON®-TB Gold In-Tube and the tuberculin skin test and predictors of positive test results in Warao Amerindian pediatric tuberculosis contacts.

    Science.gov (United States)

    Verhagen, Lilly M; Maes, Mailis; Villalba, Julian A; d'Alessandro, Adriana; Rodriguez, Lazaro Perez; España, Mercedes F; Hermans, Peter W M; de Waard, Jacobus H

    2014-07-11

    Interferon-gamma release assays have emerged as a more specific alternative to the tuberculin skin test (TST) for detection of tuberculosis (TB) infection, especially in Bacille Calmette-Guérin (BCG) vaccinated people. We determined the prevalence of Mycobacterium tuberculosis infection by TST and QuantiFERON®-TB Gold In-Tube (QFT-GIT) and assessed agreement between the two test methods and factors associated with positivity in either test in Warao Amerindian children in Venezuela. Furthermore, progression to active TB disease was evaluated for up to 12 months. 163 HIV-negative childhood household contacts under 16 years of age were enrolled for TST, QFT-GIT and chest X-ray (CXR). Follow-up was performed at six and 12 months. Factors associated with TST and QFT-GIT positivity were studied using generalized estimation equations logistic regression models. At baseline, the proportion of TST positive children was similar to the proportion of children with a positive QFT-GIT (47% vs. 42%, p = 0.12). Overall concordance between QFT-GIT and TST was substantial (kappa 0.76, 95% CI 0.46-1.06). Previous BCG vaccination was not associated with significantly increased positivity in either test (OR 0.68, 95% CI 0.32-1.5 for TST and OR 0.51, 95% CI 0.14-1.9 for QFT-GIT). Eleven children were diagnosed with active TB at baseline. QFT-GIT had a higher sensitivity for active TB (88%, 95% CI 47-98%) than TST (55%, 95% CI 24-83%) while specificities were similar (respectively 58% and 55%). Five initially asymptomatic childhood contacts progressed to active TB disease during follow-up. Replacement of TST by the QFT-GIT for detection of M. tuberculosis infection is not recommended in this resource-constrained setting as test results showed substantial concordance and TST positivity was not affected by previous BCG vaccination. The QFT-GIT had a higher sensitivity than the TST for the detection of TB disease. However, the value of the QFT-GIT as an adjunct in diagnosing TB disease is

  8. Comparison of two interferon-gamma release assays (QuantiFERON-TB Gold In-Tube and T-SPOT.TB) in testing for latent tuberculosis infection among HIV-infected adults.

    Science.gov (United States)

    Sultan, B; Benn, P; Mahungu, T; Young, M; Mercey, D; Morris-Jones, S; Miller, R F

    2013-10-01

    There is currently no 'gold standard' for diagnosis of latent tuberculosis infection (LTBI), and both the tuberculin skin test and interferon-gamma release assays (IGRAs) are used for diagnosis; the latter have a higher sensitivity than tuberculin skin tests for diagnosis of LTBI in HIV-infected individuals with lower CD4 counts. No evidence base exists for selection of IGRA methodology to identify LTBI among human immunodeficiency virus-infected patients in the UK. We prospectively evaluated two commercially available IGRA methods (QuantiFERON-TB Gold In Tube [QFG] and T-SPOT.TB) for testing LTBI among HIV-infected patients potentially nosocomially exposed to an HIV-infected patient with 'smear-positive' pulmonary tuberculosis. Among the exposed patients median CD4 count was 550 cells/µL; 105 (90%) of 117 were receiving antiretroviral therapy, of who 104 (99%) had an undetectable plasma HIV load. IGRAs were positive in 12 patients (10.3%); QFG positive in 11 (9.4%) and T-SPOT.TB positive in six (5.1%); both IGRAs were positive in five patients (4.3%). There was one indeterminate QFG and one borderline T-SPOT.TB result. Concordance between the two IGRAs was moderate (κ = 0.56, 95% confidence interval = 0.27-0.85). IGRAs were positive in only 4 (29%) of 14 patients with previous culture-proven tuberculosis. No patient developed tuberculosis during 20 months of follow-up.

  9. Contribution of a heparin-binding haemagglutinin interferon-gamma release assay to the detection of Mycobacterium tuberculosis infection in HIV-infected patients: comparison with the tuberculin skin test and the QuantiFERON-TB Gold In-tube.

    Science.gov (United States)

    Wyndham-Thomas, Chloé; Dirix, Violette; Schepers, Kinda; Martin, Charlotte; Hildebrand, Marc; Goffard, Jean-Christophe; Domont, Fanny; Libin, Myriam; Loyens, Marc; Locht, Camille; Van Vooren, Jean-Paul; Mascart, Françoise

    2015-02-14

    The screening and treatment of latent tuberculosis (TB) infection reduces the risk of progression to active disease and is currently recommended for HIV-infected patients. The aim of this study is to evaluate, in a low TB incidence setting, the potential contribution of an interferon-gamma release assay in response to the mycobacterial latency antigen Heparin-Binding Haemagglutinin (HBHA-IGRA), to the detection of Mycobacterium tuberculosis infection in HIV-infected patients. Treatment-naïve HIV-infected adults were recruited from 4 Brussels-based hospitals. Subjects underwent screening for latent TB using the HBHA-IGRA in parallel to a classical method consisting of medical history, chest X-ray, tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube (QFT-GIT). Prospective clinical and biological follow-up ensued, with repeated testing with HBHA-IGRA. A group of HIV-infected patients with clinical suspicion of active TB was also recruited and tested with the HBHA-IGRA. Multiplex analysis was performed on the culture supernatants of this in-house assay to identify test read-outs alternative to interferon-gamma that could increase the sensitivity of the test. Among 48 candidates enrolled for screening, 9 were identified with latent TB by TST and/or QFT-GIT results. Four of these 9 patients and an additional 3 screened positive with the HBHA-IGRA. This in-house assay identified all the patients that were positive for the TST and showed the best concordance with the presence of a M. tuberculosis exposure risk. During follow-up (median 14 months) no case of active TB was reported and HBHA-IGRA results remained globally constant. Fourteen HIV-infected patients with clinical suspicion of active TB were recruited. Active TB was confirmed for 6 of them among which 3 were HBHA-IGRA positive, each with very high interferon-gamma concentrations. All patients for whom active TB was finally excluded, including 2 non-tubercular mycobacterial infections, had negative HBHA

  10. QTF-Gold assay for monitoring of anti-tuberculosis therapy in subjects with active TB

    Directory of Open Access Journals (Sweden)

    Ilaria Sauzullo

    2008-09-01

    Full Text Available Introduction: The identification and characterization of two M. tuberculosis-specific antigens (ESAT-6 and CFP- 10 has led to the development of a whole blood new generation of M. tuberculosis specific diagnostic tests, that have several advantages over tuberculin skin test (TST, in terms of higher specificity, better correlation with surrogate measures of exposure to M. tuberculosis in low-incidence setting, and less cross-reactivity with M. bovis (BCG vaccine and environmental mycobacteria.The role of these new tests in evaluating post-therapy tuberculosis eradication has not been investigated yet. Aim of this longitudinal study was to determinate changes of response to M. tuberculosis-specific antigens in patients during the standard tuberculosis treatment and to investigate the in vitro effects of tuberculosis drugs on the IFN-γ release. Methods: 23 individuals with active tuberculosis were enrolled and followed over time.They were tested with QuantiFERON TB-Gold (QFT-Gold at four time points: at diagnosis (t0, after 3 and 6 months of treatment (t1- t2 and at the end of the specific treatment (t3. Results: At baseline all patients were positive by QFT-Gold.At second time-point 17 out of 23 (74% were positive, at third time-point 11 of 23 (47% were positive, at treatment completion 3/23 (13% were positive.The conversion to negative response to M. tuberculosis-specific antigens was found in 87% patients analyzed after successful therapy. Longitudinal QFT-Gold testing shown a significant decrease (p<0.001 of IFN-γ response during the therapy. No inhibitory effect on IFN-γ release was noted in vitro for chemotherapy using at concentrations compatible with those achieved in serum of treated patients.We have revealed an inhibitory effect only at concentrations 2-3 times greater than those previously tested. Conclusion: A successful therapy for tuberculosis causes a significant decrease of the ESAT-6 and CFP-10 response and this data suggest

  11. Prednisolone treatment affects the performance of the QuantiFERON gold in-tube test and the tuberculin skin test in patients with autoimmune disorders screened for latent tuberculosis infection

    DEFF Research Database (Denmark)

    Bélard, Erika; Semb, Synne; Ruhwald, Morten

    2011-01-01

    BACKGROUND: During screening for latent tuberculosis infection (LTBI), before anti-tumor-necrosis-factor-a treatment, most patients are already receiving immunosuppressive therapy. The objective was to evaluate the performance of the QuantiFERON Gold In-Tube (QFT-IT) and the Tuberculin Skin Test....../238 (23%) patients. Chest x-ray was suspect for tuberculosis in 5/236 (2%), and 35/167 (21%) had =1 risk-factors for infection with Mycobacterium tuberculosis. The main finding was a pronounced negative effect on QFT-IT and TST performance associated with prednisolone treatment. During prednisolone...... treatment interferon gamma (IFN-¿) response to mitogen stimulation was impaired (median IFN-¿ response 4.9 IU/mL; interquartile range [IQR] 0.8 to =10.0) compared to patients 1) not receiving corticosteroids (median =10.0; IQR 5.0 to =10.0; P = 0.0015) or 2) receiving long-acting corticosteroids (median >10...

  12. Influence of age and nutritional status on the performance of the tuberculin skin test and QuantiFERON-TB gold in-tube in young children evaluated for tuberculosis in Southern India.

    Science.gov (United States)

    Jenum, Synne; Selvam, Sumithra; Mahelai, Diana; Jesuraj, Nelson; Cárdenas, Vicky; Kenneth, John; Hesseling, Anneke C; Doherty, Timothy Mark; Vaz, Mario; Grewal, Harleen M S

    2014-10-01

    Reliable identification of Mycobacterium tuberculosis infection or tuberculosis (TB) disease in young children is vital to assure adequate preventive and curative treatment. The tuberculin skin test (TST) and IFNγ-release assays may supplement the diagnosis of pediatric TB as cases are typically bacteriologically unconfirmed. However, it is unclear to what extent the performance of TST and QuantiFERON-TB Gold In-Tube (QFT; Cellestis' IFNγ-release assay test) depends on the demographic, clinical and nutritional characteristics of children in whom they are tested. During a 2-year prospective observational study of 4382 neonates in Southern India, children with suspected TB were investigated and classified by a standard TB diagnostic algorithm. Clinical TB was diagnosed in 13 of 705 children referred for case verification with suspected TB. TST and QFT had a susceptibility for clinical TB of 31% and 23%, respectively, in this group. Children tuberculosis infection and more prone to indeterminate QFT results. TST was less reliable in children with wasting.

  13. Diagnosis and follow-up of treatment of latent tuberculosis; the utility of the QuantiFERON-TB Gold In-tube assay in outpatients from a tuberculosis low-endemic country

    Directory of Open Access Journals (Sweden)

    Blomberg Bjørn

    2010-03-01

    Full Text Available Abstract Background Interferon-gamma (IFN-γ Release Assays (IGRA are more specific than the tuberculosis skin test (TST in the diagnosis of latent tuberculosis (TB infection (LTBI. We present the performance of the QuantiFERON®-TB Gold In-tube (QFT-TB assay as diagnostic test and during follow-up of preventive TB therapy in outpatients from a TB low-endemic country. Methods 481 persons with suspected TB infection were tested with QFT-TB. Thoracic X-ray and sputum samples were performed and a questionnaire concerning risk factors for TB was filled. Three months of isoniazid and rifampicin were given to patients with LTBI and QFT-TB tests were performed after three and 15 months. Results The QFT-TB test was positive in 30.8% (148/481 of the total, in 66.9% (111/166 of persons with origin from a TB endemic country, in 71.4% (20/28 previously treated for TB and in 100% (15/15 of those diagnosed with active TB with no inconclusive results. The QFT-TB test was more frequently positive in those with TST ≥ 15 mm (47.5% compared to TST 11-14 mm (21.3% and TST 6-10 mm (10.5%, (p 0.05. Conclusion Only one third of those with suspected TB infection had a positive QFT-TB test. Recent immigration from TB endemic countries and long duration of exposure are risk factors for a positive QFT-TB test and these groups should be targeted through screening. Since most patients remained QFT-TB positive after therapy, the test should not be used to monitor the effect of preventive therapy. Prospective studies are needed in order to determine the usefulness of IGRA tests during therapy.

  14. Impact of tuberculosis treatment and antiretroviral therapy on serial RD-1-specific quantitative T-cell readouts (QuantiFERON-TB Gold In-Tube), and relationship to treatment-related outcomes and bacterial burden.

    Science.gov (United States)

    Mthiyane, Thuli; Rustomjee, Roxana; Pym, Alex; Connolly, Cathy; Onyebujoh, Philip; Theron, Grant; Dheda, Keertan

    2015-07-01

    The impact of anti-tuberculosis treatment with and without antiretroviral therapy (ART) on standardized interferon gamma release assay (IGRA) readouts has been studied inadequately in high-burden countries. The QuantiFERON-TB Gold In-Tube (QFT-GIT) test was used to evaluate interferon gamma (IFN-γ) responses longitudinally (0, 3, 6, and 12 months post initiation of tuberculosis (TB)-HIV co-treatment or ART alone) in 82 HIV-infected patients. Of the 65 evaluable participants, 30 were co-infected on ART, 17 were co-infected but not on ART, and 18 were HIV-infected alone and on ART. In HIV-infected and HIV-TB-infected patients on ART, IFN-γ responses increased, whilst they decreased in those not on ART. However, baseline, month 3, and month 6 IFN-γ responses, irrespective of ART, did not differ in TB-HIV co-infected patients who culture-converted compared to those who did not (1.25 vs. 1.05, p=0.5 at baseline; 3.76 vs. 1.15, p=0.2 for month 3; 0.06 vs. 0.7, p=0.3 for month 6). IFN-γ levels did not correlate with the magnitude of sputum bacillary load, smear status, or liquid culture time-to-positivity. As IGRAs do not correlate with 2- or 6-month culture conversion or with markers of bacillary burden, they are unlikely to be useful for the prognostication of treatment outcome in co-infected patients. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. [Comparative study of concordance and costs between tuberculin skin test and QuantiFERON(®)-TB Gold In-Tube in the diagnosis of latent tuberculosis infection among contacts of patients with pulmonary tuberculosis].

    Science.gov (United States)

    Martinez Lacasa, Xavier; Canals Font, Roser; Jaen Manzanera, Angels; Cuchi Burgos, Eva; Lite Lite, Josep

    2015-11-20

    Recently diagnosis of latent tuberculosis infection (LTBI) can be made using the tuberculin skin test (TST) or by techniques known as interferon-γ release assays (IGRAS), being QuantiFERON(®)-TB Gold In-Tube (QF-G-IT) the most used. The IGRAS avoid some drawbacks of the TST, especially cross-reaction with bacillus Calmette-Guérin (BCG) vaccine, but also present some problems such as those arising from cost and the need of having an adequate infrastructure and experience. There is no clear consensus on which technique should be preferentially used for the diagnosis of LTBI. This is a comparative study between the TST and QT-G-IT in a cohort of contacts of patients with pulmonary tuberculosis during the study period. An analysis of global agreement and groups was performed according to whether the contacts were vaccinated with BCG or not. A study of costs of both techniques and diagnostic strategies based on these techniques was performed. The agreement between TST and QF-G-IT was acceptable in the whole sample yet it was very good in the unvaccinated group. Few cases of indeterminate values were recorded. The cost study showed that TST was cheaper than QF-G-IT; however when we analyzed the cost of the strategies according to each technique, the QF-G-IT showed a better cost-benefit. We suggest considering QF-G-IT as the only preferred technique for the diagnosis of LTBI in household contacts, based on good overall agreement between the 2 techniques (even if we eliminate the effect of the vaccine) and a cost analysis favorable to QF-G-IT. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.

  16. Mycobacterium Tuberculosis Infection, Immigration Status, and Diagnostic Discordance: A Comparison of Tuberculin Skin Test and QuantiFERON-TB Gold In-Tube Test Among Immigrants to the U.S.

    Science.gov (United States)

    Wilson, Fernando A; Miller, Thaddeus L; Stimpson, Jim P

    2016-01-01

    We used a recent source of nationally representative population data on tuberculosis (TB) infection to characterize concordance between the tuberculin skin test (TST) and the QuantiFERON-TB Gold In-Tube (QFT-GIT) blood test for immigrants in the United States. We used TB screening data from the 2011-2012 National Health and Nutrition Examination Survey to examine concordance between the TST and QFT-GIT--an interferon-gamma release assay (IGRA) blood test--for 7,097 U.S. natives, naturalized citizens, and noncitizens. Consistent with prior findings, one in five immigrants in the survey was identified with latent TB infection (LTBI), a rate 14 times higher than for U.S. natives. We also found higher rates of discordant TST/IGRA results among immigrants than among U.S. natives. Unadjusted discordance between TST and IGRA was 3% among U.S. natives (weighted N=5,684,274 of 191,179,213) but ranged up to 19% for noncitizens (weighted N=3,722,960 of 19,377,147). Adjusting for age, sex, and race/ethnicity, noncitizens had more than nine times the odds of having a positive TST result but negative QFT-GIT result compared with U.S. natives. Our findings suggest that whether and how either of these tests should be deployed is highly context sensitive. Significant discordance in test results when used among immigrants raises the possibility of missed opportunities for harm reduction in this already at-risk population. However, we found little distinction between the tests in terms of diagnostic outcome when used in a U.S. native population, suggesting little benefit to the adoption and use of the QFT-GIT test in place of TST on the basis of test performance alone for this population.

  17. Tuberculosis screening by tuberculosis skin test or QuantiFERON-TB Gold In-Tube Assay among an immigrant population with a high prevalence of tuberculosis and BCG vaccination.

    Science.gov (United States)

    Painter, John A; Graviss, Edward A; Hai, Hoang Hoa; Nhung, Duong Thi Cam; Nga, Tran Thi Thanh; Ha, Ngan P; Wall, Kirsten; Loan, Le Thien Huong; Parker, Matt; Manangan, Lilia; O'Brien, Rick; Maloney, Susan A; Hoekstra, R M; Reves, Randall

    2013-01-01

    Each year 1 million persons acquire permanent U.S. residency visas after tuberculosis (TB) screening. Most applicants undergo a 2-stage screening with tuberculin skin test (TST) followed by CXR only if TST-positive at > 5 mm. Due to cross reaction with bacillus Calmette-Guérin (BCG), TST may yield false positive results in BCG-vaccinated persons. Interferon gamma release assays exclude antigens found in BCG. In Vietnam, like most high TB-prevalence countries, there is universal BCG vaccination at birth. 1. Compare the sensitivity of QuantiFERON-TB Gold In-Tube Assay (QFT) and TST for culture-positive pulmonary TB. 2. Compare the age-specific and overall prevalence of positive TST and QFT among applicants with normal and abnormal CXR. We obtained TST and QFT results on 996 applicants with abnormal CXR, of whom 132 had TB, and 479 with normal CXR. The sensitivity for tuberculosis was 86.4% for QFT; 89.4%, 81.1%, and 52.3% for TST at 5, 10, and 15 mm. The estimated prevalence of positive results at age 15-19 years was 22% and 42% for QFT and TST at 10 mm, respectively. The prevalence increased thereafter by 0.7% year of age for TST and 2.1% for QFT, the latter being more consistent with the increase in TB among applicants. During 2-stage screening, QFT is as sensitive as TST in detecting TB with fewer requiring CXR and being diagnosed with LTBI. These data support the use of QFT over TST in this population.

  18. The frequencies of IFNγ+IL2+TNFα+ PPD-specific CD4+CD45RO+ T-cells correlate with the magnitude of the QuantiFERON® gold in-tube response in a prospective study of healthy indian adolescents.

    Directory of Open Access Journals (Sweden)

    Synne Jenum

    Full Text Available BACKGROUND: QuantiFERON-TB Gold In-Tube (QFT is an IFNγ-release assay used in the diagnosis of Mycobacterium tuberculosis (MTB infection. The risk of TB progression increases with the magnitude of the MTB-specific IFNγ-response. QFT reversion, also associated with low Tuberculin Skin Test responses, may therefore represent a transient immune response with control of M. tuberculosis infection. However, studies at the single cell level have suggested that the quality (polyfunctionality of the T-cell response is more important than the quantity of cytokines produced. OBJECTIVE: To explore the quality and/or magnitude of mycobacteria-specific T-cell responses associated with QFT reversion and persistent QFT-positivity. METHODS: Multi-color flowcytometry on prospectively collected peripheral blood mononuclear cells was applied to assess mycobacteria-specific T-cell responses in 42 QFT positive Indian adolescents of whom 21 became QFT negative (reverters within one year. Ten QFT consistent negatives were also included as controls. RESULTS: There was no difference in the qualitative PPD-specific CD4+ T-cell response between QFT consistent positives and reverters. However, compared with QFT consistent positives, reverters displayed lower absolute frequencies of polyfunctional (IFNγ+IL2+TNFα+ CD4+ T-cells at baseline, which were further reduced to the point where they were not different to QFT negative controls one year later. Moreover, absolute frequencies of these cells correlated well with the magnitude of the QFT-response. CONCLUSION: Whereas specific polyfunctional CD4+ T-cells have been suggested to protect against TB progression, our data do not support that higher relative or absolute frequencies of PPD-specific polyfunctional CD4+ T-cells in peripheral blood can explain the reduced risk of TB progression observed in QFT reverters. On the contrary, absolute frequencies of these cells correlated with the QFT-response, suggesting that this

  19. Tuberculosis Infection in Zambia: The Association with Relative Wealth

    OpenAIRE

    2009-01-01

    This study aimed to assess the association between household socioeconomic position and tuberculosis (TB) infection in two communities of Zambia. For this purpose we implemented a cross-sectional investigation, nested within a larger case control study. Infection was assessed using Quantiferon-TB Gold. A socioeconomic position index was constructed through principal component analysis combining data on human resources, food availability, housing quality, and access to services and infrastruct...

  20. Gold Rush!

    Science.gov (United States)

    Brahier, Daniel J.

    1997-01-01

    Describes a mathematical investigation of gold--how it is weighed, stored, used, and valued. For grades 3-4, children estimate the value of treasure chests filled with gold coins and explore the size and weight of gold bars. Children in grades 5-6 explore how gold is mined and used, and how the value of gold changes over time. (PVD)

  1. Interferon Gamma-Based Detection of Latent Tuberculosis Infection in the Border States of Nuevo Leon and Tamaulipas, Mexico.

    Science.gov (United States)

    Oren, Eyal; Alatorre-Izaguirre, Gabriela; Vargas-Villarreal, Javier; Moreno-Treviño, Maria Guadalupe; Garcialuna-Martinez, Javier; Gonzalez-Salazar, Francisco

    2015-01-01

    Nearly one-third of the world's population is infected with latent tuberculosis (LTBI). Tuberculosis (TB) rates in the border states are higher than national rates in both the US and Mexico, with the border accounting for 30% of total registered TB cases in both countries. However, LTBI rates in the general population in Mexican border states are unknown. In this region, LTBI is diagnosed using the tuberculin skin test (TST). New methods of detection more specific than TST have been developed, although there is currently no gold standard for LTBI detection. Our objective is to demonstrate utility of the Quantiferon TB gold In-Tube (QFT-GIT) test compared with the TST to detect LTBI among border populations. This is an observational, cross-sectional study carried out in border areas of the states of Nuevo Leon and Tamaulipas, Mexico. Participants (n = 210) provided a TST and blood sample for the QFT-GIT. Kappa coefficients assessed the agreement between TST and QFT-GIT. Participant characteristics were compared using Fisher exact tests. Thirty-eight percent of participants were diagnosed with LTBI by QFT-GIT. The proportion of LTBI detected using QFT-GIT was almost double [38% (79/210)] that found by TST [19% (39/210)] (P < 0.001). Concordance between TST and QFT-GIT was low (kappa = 0.37). We recommend further studies utilizing the QFT-GIT test to detect LTBI among border populations.

  2. Effect of Pregnancy on Interferon Gamma Release Assay and Tuberculin Skin Test Detection of Latent TB Infection Among HIV-Infected Women in a High Burden Setting.

    Science.gov (United States)

    LaCourse, Sylvia M; Cranmer, Lisa M; Matemo, Daniel; Kinuthia, John; Richardson, Barbra A; Horne, David J; John-Stewart, Grace

    2017-05-01

    Peripartum immunologic changes may affect latent tuberculosis infection (LTBI) diagnostic performance among HIV-infected women. HIV-infected women were serially tested with tuberculin skin test (TST) and interferon gamma release assay [QuantiFERON TB Gold In-tube (QFT)] in pregnancy and 6 weeks postpartum in Kenya. Prevalence, sensitivity and agreement, and correlates of QFT/TST positivity were assessed. Quantitative QFT mitogen and Mycobacterium tuberculosis antigen (Mtb-Ag) responses were compared by peripartum stage. Incidence of test conversion at 6 weeks postpartum was evaluated in baseline TST-/QFT- women. Among 100 HIV-infected women, median age was 26 years, median CD4 was 555 cells per cubic millimeter, and 88% were on antiretrovirals. More women were QFT+ than TST+ in both pregnancy (35.4% vs. 13.5%, P = 0.001) and postpartum (29.6% vs. 14.8%, P 2-fold more women with LTBI compared with TST in pregnancy and postpartum. Lower QFT Mtb-Ag and mitogen responses in pregnancy compared with postpartum suggest that pregnancy-associated immunologic changes may influence LTBI test performance.

  3. Impairment of IFN-gamma response to synthetic peptides of Mycobacterium tuberculosis in a 7-day whole blood assay.

    Directory of Open Access Journals (Sweden)

    Hannah Priyadarshini Gideon

    Full Text Available Studies on Mycobacterium tuberculosis (MTB antigens are of interest in order to improve vaccine efficacy and to define biomarkers for diagnosis and treatment monitoring. The methodologies used for these investigations differ greatly between laboratories and discordant results are common. The IFN-gamma response to two well characterized MTB antigens ESAT-6 and CFP-10, in the form of recombinant proteins and synthetic peptides, was evaluated in HIV-1 uninfected persons in both long-term (7 day and 24 hour, commercially available QuantiFERON TB Gold in Tube (QFT-GIT, whole blood assays. Our findings showed differences in the IFN-gamma response between 24 hour and 7 day cultures, with recombinant proteins inducing a significantly higher response than the peptide pools in 7 day whole blood assays. The activity of peptides and recombinant proteins did not differ in 24 hour whole blood or peripheral blood mononuclear cell (PBMC based assays, nor in the ELISpot assay. Further analysis by SELDI-TOF mass spectrometry showed that the peptides are degraded over the course of 7 days of incubation in whole blood whilst the recombinant proteins remain intact. This study therefore demonstrates that screening antigenic candidates as synthetic peptides in long-term whole blood assays may underestimate immunogenicity.

  4. Strong boundedness of analytic functions in tubes

    Directory of Open Access Journals (Sweden)

    Richard D. Carmichael

    1979-01-01

    Full Text Available Certain classes of analytic functions in tube domains TC=ℝn+iC in n-dimensional complex space, where C is an open connected cone in ℝn, are studied. We show that the functions have a boundedness property in the strong topology of the space of tempered distributions g′. We further give a direct proof that each analytic function attains the Fourier transform of its spectral function as distributional boundary value in the strong (and weak topology of g′.

  5. Comparing interferon-gamma release assays to tuberculin skin test in Thai children with tuberculosis exposure.

    Directory of Open Access Journals (Sweden)

    Hong-Van Tieu

    Full Text Available Data on the performance of interferon-gamma release assays (IGRAs, QuantiFERON TB Gold In-tube (QFNGIT and T-Spot.TB, in diagnosing tuberculosis (TB are limited in Southeast Asia. This study aims to compare the performances of the two IGRAs and TST in Thai children with recent TB exposure.This multicenter, prospective study enrolled children with recent exposure to active TB adults. Children were investigated for active TB. TST was performed and blood collected for T-Spot.TB and QFNGIT.158 children were enrolled (87% TB-exposed and 13% active TB, mean age 7.2 years. Only 3 children had HIV infection. 66.7% had TST≥10 mm, while 38.6% had TST≥15 mm. 32.5% had positive QFNGIT; 29.9% had positive T-Spot.TB. QFNGIT and T-Spot.TB positivity was higher among children with active TB compared with TB-exposed children. No indeterminate IGRA results were detected. No statistically significant differences between the performances of the IGRAs and TST at the two cut-offs with increasing TB exposure were detected. Concordance for positive IGRAs and TST ranged from 42-46% for TST≥10 mm and 62-67% for TST≥15 mm. On multivariable analyses, exposure to household primary/secondary caregiver with TB was associated with positive QFNGIT. Higher TB contact score and active TB were associated with positive T-Spot.TB.Both QFNGIT and T-Spot.TB performed well in our Thai pediatric study population. No differences in the performances between tests with increasing TB exposure were found. Due to accessibility and low cost, using TST may more ideal than IGRAs in diagnosing latent and active TB in healthy children in Thailand and other similar settings.

  6. Predictors of low prevalence of latent tuberculosis infection among Egyptian health care workers at intensive care and bronchoscopy units

    Science.gov (United States)

    Hefzy, Enas Mamdouh; Wegdan, Ahmed Ashraf; Elhefny, Radwa Ahmed; Nasser, Samar Hassan

    2016-01-01

    Aim: Latent tuberculosis infections (LTBI) contain a significant reservoir for future epidemics. Screening of health care workers (HCWs) in a high-risk tuberculosis (TB) environment is an important strategy in TB control. The study aimed to assess the prevalence of LTBI among high risk Egyptian HCWs and to assess infection associated risk factors. Methods: Fifty-two HCWs who work at intensive care unit (ICU), bronchoscopy unit, and chest diseases department were tested for LTBI using both tuberculin skin test (TST) and Quantiferon TB Gold in-tube test (QFT). Risk factors for infection, knowledge of HCWs towards different aspects of TB infection and agreement between TST and QFT were also evaluated. Results: Prevalence of LTBI in this study was 13.5% by QFT and TST. It was 13.6% by TST alone and 10.3% by QFT alone. There was good concordance between both tests (Kappa=0.713). There was a statistically significant association between prevalence of LTBI and age of staff ≥30 yr (p=0.002), period of working experience (p=0.006) and working at the Bronchoscopy Unit (p=0.001). The total knowledge of HCWs towards different aspects of TB infection was generally good. Conclusion: Although the participants in the current study were among high risk HCWs, the prevalence of LTBI was low. Bacille Calmette-Guerin (BCG) vaccination, young age, short employment duration, good knowledge and a good infection control were the predictors of low risk of contracting TB at our hospitals. The risk of TB infection in resource-limited countries can be reduced with simple continuous educational and administrative infection control programmes. PMID:27777875

  7. The microbiological diagnosis of tuberculous meningitis: results of Haydarpasa-1 study.

    Science.gov (United States)

    Erdem, H; Ozturk-Engin, D; Elaldi, N; Gulsun, S; Sengoz, G; Crisan, A; Johansen, I S; Inan, A; Nechifor, M; Al-Mahdawi, A; Civljak, R; Ozguler, M; Savic, B; Ceran, N; Cacopardo, B; Inal, A S; Namiduru, M; Dayan, S; Kayabas, U; Parlak, E; Khalifa, A; Kursun, E; Sipahi, O R; Yemisen, M; Akbulut, A; Bitirgen, M; Dulovic, O; Kandemir, B; Luca, C; Parlak, M; Stahl, J P; Pehlivanoglu, F; Simeon, S; Ulu-Kilic, A; Yasar, K; Yilmaz, G; Yilmaz, E; Beovic, B; Catroux, M; Lakatos, B; Sunbul, M; Oncul, O; Alabay, S; Sahin-Horasan, E; Kose, S; Shehata, G; Andre, K; Alp, A; Cosić, G; Cem Gul, H; Karakas, A; Chadapaud, S; Hansmann, Y; Harxhi, A; Kirova, V; Masse-Chabredier, I; Oncu, S; Sener, A; Tekin, R; Deveci, O; Karabay, O; Agalar, C

    2014-10-01

    We aimed to provide data on the diagnosis of tuberculous meningitis (TBM) in this largest case series ever reported. The Haydarpasa-1 study involved patients with microbiologically confirmed TBM in Albania, Croatia, Denmark, Egypt, France, Hungary, Iraq, Italy, Macedonia, Romania, Serbia, Slovenia, Syria and Turkey between 2000 and 2012. A positive culture, PCR or Ehrlich-Ziehl-Neelsen staining (EZNs) from the cerebrospinal fluid (CSF) was mandatory for inclusion of meningitis patients. A total of 506 TBM patients were included. The sensitivities of the tests were as follows: interferon-γ release assay (Quantiferon TB gold in tube) 90.2%, automated culture systems (ACS) 81.8%, Löwenstein Jensen medium (L-J) 72.7%, adenosine deaminase (ADA) 29.9% and EZNs 27.3%. CSF-ACS was superior to CSF L-J culture and CSF-PCR (p <0.05 for both). Accordingly, CSF L-J culture was superior to CSF-PCR (p <0.05). Combination of L-J and ACS was superior to using these tests alone (p <0.05). There were poor and inverse agreements between EZNs and L-J culture (κ = -0.189); ACS and L-J culture (κ = -0.172) (p <0.05 for both). Fair and inverse agreement was detected for CSF-ADA and CSF-PCR (κ = -0.299, p <0.05). Diagnostic accuracy of TBM was increased when both ACS and L-J cultures were used together. Non-culture tests contributed to TBM diagnosis to a degree. However, due to the delays in the diagnosis with any of the cultures, combined use of non-culture tests appears to contribute early diagnosis. Hence, the diagnostic approach to TBM should be individualized according to the technical capacities of medical institutions particularly in those with poor resources.

  8. Interferon Gamma Release Assay versus Tuberculin Skin Testing among Healthcare Workers of Highly Diverse Origin in a Moderate Tuberculosis Burden Country.

    Science.gov (United States)

    Al Hajoj, Sahal; Varghese, Bright; Datijan, Alria; Shoukri, Mohammed; Alzahrani, Ali; Alkhenizan, Abdallah; AlSaif, Abdulaziz; Althawadi, Sahar; Fernandez, Grace; Alrajhi, Abdulrahman

    2016-01-01

    Health care workers (HCW's) are always at an increased risk of contracting tuberculosis (TB) infection. In Saudi Arabia, Interferon Gamma Release Assay (IGRA) has not been evaluated as a screening tool for latent TB infection (LTBI) among HCW's considering their high demographic diversity. During February 2012 to January 2015 a cross sectional study has been conducted in a tertiary care center with maximum demographically diverse staff population in the capital city-Riyadh. After a short interview and consenting, all the candidates were subjected to tuberculin skin test (TST) and QuantiFERON TB gold In-tube test (QFT). A logistic regression analysis was carried out for establishing the associations between putative risk factors and the diagnostic tests. The candidates were classified according to geographical origin and a detailed analysis was conducted on the impact of their origin towards the results of TST and QFT. Of the 1595 candidates enrolled, 90.6% were BCG vaccinated, female (67.9%) and mainly nurses (53.2%). Candidates with high risk of suspected or confirmed TB patient exposure were 56.1% and 76.5% of them had origin were associated with TST positivity while Occupational TB exposure and geographical origin of the candidates were associated with QFT positivity. A regular follow up on recently TST converted candidates showed no progression to active TB. The putative factors associated with the discordance were origin of the candidate (p value Origin of the candidates has strong association with the results of TST and QFT. The discordant results particularly TST negative and QFT positive needs more detailed analysis.

  9. Black gold

    CERN Document Server

    Fletcher, MW

    2016-01-01

    Following the Yom Kippur war of October 1973, OPEC raises the price of oil by 70% along with a 5% reduction in oil production. Len Saunders a highly skilled and knowledgeable British engineer for Jaguar motors, is approached by the UK energy commission in the January of 1974 to create a new propulsion system; using a secret document from a German WW2 scientist, that they have come into possession of. Len Saunders sets to work on creating the holy grail of energy. Seven years later 1981, Haidar Farooq the Kuwait oil minister working at OPEC and head of a secret organisation named Black Gold bec

  10. Going for Gold

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    While the international gold price in February hit the highest point in 25 years at $541.20 per ounce for futures delivery, a new gold rush is sweeping across China. According to the World Gold Council, the London-based gold marketing organization funded by leading global gold mining firms, the purchase of gold products in China grew by 9 percent in the first nine

  11. Gold in Modern Economy

    Directory of Open Access Journals (Sweden)

    Boryshkevych Olena V.

    2014-01-01

    Full Text Available The article studies the role of gold in modern economy. It analyses dynamics and modern state of the gold market. It studies volumes of contracts in exchange and off-exchange markets. In order to reveal changes of key features of the gold market, it focuses on the study of gold demand volumes, studies volumes and geographical changes in the world gold mining, and analyses volumes of monetary gold of central banks and its share in gold and currency reserves. It analyses price fluctuations in the gold market during 1968 – 2013 and identifies main factors that determine the gold price. It identifies interconnection between the state of the gold market and financial markets of countries. The study showed that namely geopolitical and economic instability restricts the spectrum of financial assets for investing and gold is not only a safe investment object but also a profitable one.

  12. Novel drive mechanism for in-tube micro robots

    Institute of Scientific and Technical Information of China (English)

    CHEN Yangzhi; XING Guangquan; PENG Xuefei; LIU Wenguang; YAO Huaping

    2007-01-01

    The volume of an in-tube micro robot is small and its interior space is very limited. However, conventional transmission methods are unfit to drive in-tube micro robots. A novel micro drive mechanism called the micro-elastic- meshing-wheel is presented in this paper. It can be used for transmitting power and locomotion between two shafts, which are upright and cross in a micro space. The mechanical model of the novel drive mechanism is built, and the maximal trans- mission force is deduced. Then, sufficient experiments are carried out to test maximal transmission force produced by the novel drive mechanism. The calculation and experiment results show that the novel drive mechanism can transmit sufficient power to in-tube micro robots.

  13. Gold induced apoptsis study

    DEFF Research Database (Denmark)

    Laustsen, Christoffer

    2008-01-01

    Introduction   Cancer cells are highly thermo sensitive. On the basis of an article in Nature the idea arose, for a new non-invasive thermotherapy technique, based on radio frequency inductive heating of nano gold particles in an MR-scanner. Thermotherapy is getting considerably attention...... at the moment, especially in the fields of lasers, they though have some problems concerning the placement of the tumor in the human body. Local heating by MR has tremendous advance in comparison too lasers. The first step is to validate the hypothesis of the inductive heating of the gold nano particles trough...... in silico methods are here proposed for apoptosis studies and for AMG studies.   Methods   MR - heating of high concentration micrometer gold and low concentration nano gold.   CSLM of ethidum bromide stained cell lines, with and witout gold and automated image processing.   AMG gold uptake study...

  14. Gold in the Books

    Institute of Scientific and Technical Information of China (English)

    江河

    2002-01-01

    In the present Chinese market, more and more businessmen turn to the profit-making trade. Even some counters in the bookstores are selling gold rings, necklaces, bracelets, etc. One day a school teacher asked a store assistant,“Why are you selling gold in your bookstore?”

  15. Gold-Mining

    DEFF Research Database (Denmark)

    Raaballe, J.; Grundy, B.D.

    2002-01-01

    of operating gold mines. Asymmetric information on the reserves in the mine implies that, at a high enough price of gold, the manager of high type finds the extraction value of the company to be higher than the current market value of the non-operating gold mine. Due to this under valuation the maxim of market...... value maximization forces the manager of high type to extract the gold.The implications are three-fold. First, all managers (except the lowest type) extract the gold too soon compared to the first-best policy of leaving the gold in the mine forever. Second, a manager of high type extracts the gold...... sooner than a manager of lower type. Third, a non-operating gold mine is valued as being of the lowest type in the pool and all else equal, high-asymmetri mines are valued lower than low-asymmetri mines. In a qualitative sense these results are robust with respect to different assumptions (re cost...

  16. 16 CFR Appendix to Part 23 - Exemptions Recognized in the Assay for Quality of Gold Alloy, Gold Filled, Gold Overlay, Rolled...

    Science.gov (United States)

    2010-01-01

    ... Quality of Gold Alloy, Gold Filled, Gold Overlay, Rolled Gold Plate, Silver, and Platinum Industry...—Exemptions Recognized in the Assay for Quality of Gold Alloy, Gold Filled, Gold Overlay, Rolled Gold Plate... be considered in any assay for quality of a gold filled, gold overlay and rolled gold plate industry...

  17. Hydraulic drag at the condensing steam flow in tubes

    Science.gov (United States)

    Leontiev, A. I.; Milman, O. O.

    2014-12-01

    The dependency of condensing steam flow parameters in tubes and channels was studied as a function of different flow modes for the coolant: counter-flow, co-flow, cross-flow. The drop for the total pressure of steam is higher for the counter-flow than for the co-flow or cross-flow modes. The pressure drop was estimated with different computation models as a function flow mode. Calculation results were compared with experimental data.

  18. Prelude to Gold

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    FEMALE Chinese athletes Fu Mingxia and Wang Junxia recorded outstanding performances at 1996 Atlanta Olympic Games. Fu Mingxia won gold medals in both platform and springboard diving, and in so doing became the first double medal winner in Olympic diving since 1960. Wang Junxia, the holder of several world records in women’s long distance events, struggled against the odds and captured gold in the 5,000-meter event,

  19. Gold nanoprobes for theranostics

    Science.gov (United States)

    Panchapakesan, Balaji; Book-Newell, Brittany; Sethu, Palaniappan; Rao, Madhusudhana; Irudayaraj, Joseph

    2011-01-01

    Gold nanoprobes have become attractive diagnostic and therapeutic agents in medicine and life sciences research owing to their reproducible synthesis with atomic level precision, unique physical and chemical properties, versatility of their morphologies, flexibility in functionalization, ease of targeting, efficiency in drug delivery and opportunities for multimodal therapy. This review highlights some of the recent advances and the potential for gold nanoprobes in theranostics. PMID:22122586

  20. The Gold Standard Programme

    DEFF Research Database (Denmark)

    Neumann, Tim; Rasmussen, Mette; Ghith, Nermin

    2013-01-01

    To evaluate the real-life effect of an evidence-based Gold Standard Programme (GSP) for smoking cessation interventions in disadvantaged patients and to identify modifiable factors that consistently produce the highest abstinence rates.......To evaluate the real-life effect of an evidence-based Gold Standard Programme (GSP) for smoking cessation interventions in disadvantaged patients and to identify modifiable factors that consistently produce the highest abstinence rates....

  1. Joining the Gold Rush

    Institute of Scientific and Technical Information of China (English)

    LIU BO

    2006-01-01

    @@ Flush with advanced technology and large amounts of capital, overseas mining firms are carving a place in the Chinese gold industry Dozens of Western mining companies, particularly those from Canada, are making the journey into the kind of remote corners in China that other overseas investors shy away from. What are they looking for? The answer is one of the most precious substances on the planet: gold.

  2. Propagation of Quasi-plane Nonlinear Waves in Tubes

    Directory of Open Access Journals (Sweden)

    P. Koníček

    2002-01-01

    Full Text Available This paper deals with possibilities of using the generalized Burgers equation and the KZK equation to describe nonlinear waves in circular ducts. A new method for calculating of diffraction effects taking into account boundary layer effects is described. The results of numerical solutions of the model equations are compared. Finally, the limits of validity of the used model equations are discussed with respect to boundary conditions and the radius of the circular duct. The limits of applicability of the KZK equation and the GBE equation for describing nonlinear waves in tubes are discussed.

  3. Frictional Characteristics and Heat Transfer of Antimisting Fuels in Tubes.

    Science.gov (United States)

    1982-08-01

    m l innl il mmlliillmp i 3 For turbulent flow: Nu = Nu f (Re, Pr, 1b/11w) * Sieder and Tate (reference 7) suggested empirical equations to...Hence, values of hw obtained using equation A.5 are confirmed by this result. Figure 28 shows that data of 0.3 percent FM-9 ANK collapse onto Sieder ...34, Transaction of ASME, June 1972. 7. Sieder , E. N. and Tate, G. E., "Heat Transfer and Pressure Drop of Liquids in Tube", Industrial and Engineering Chemistry, V

  4. GOLD IS EARNED FROM THE PRODUCTION OF THAI GOLD LEAF

    Directory of Open Access Journals (Sweden)

    Dirk Bax

    2010-06-01

    Full Text Available Thai people like to cover sacred objects or things dear to them with gold leaf.. Statues of Buddha are sometimes covered with so many layers of gold leaf that they become formless figures, that can hardly be recognized. Portraits of beloved ancestors, statues of elephants and grave tombs are often covered with gold leaf. If one considers the number of Thai people and the popularity of the habit, the amount of gold involved could be considerable.

  5. The impact of HIV infection and CD4 cell count on the performance of an interferon gamma release assay in patients with pulmonary tuberculosis.

    Directory of Open Access Journals (Sweden)

    Martine G Aabye

    Full Text Available BACKGROUND: The performance of the tuberculosis specific Interferon Gamma Release Assays (IGRAs has not been sufficiently documented in tuberculosis- and HIV-endemic settings. This study evaluated the sensitivity of the QuantiFERON TB-Gold In-Tube (QFT-IT in patients with culture confirmed pulmonary tuberculosis (PTB in a TB- and HIV-endemic population and the effect of HIV-infection and CD4 cell count on test performance. METHODOLOGY/PRINCIPAL FINDINGS: 161 patients with sputum culture confirmed PTB were subjected to HIV- and QFT-IT testing and measurement of CD4 cell count. The QFT-IT was positive in 74% (119/161; 95% CI: 67-81%. Sensitivity was higher in HIV-negative (75/93 than in HIV-positive (44/68 patients (81% vs. 65%, p = 0.02 and increased with CD4 cell count in HIV-positive patients (test for trend p = 0.03. 23 patients (14% had an indeterminate result and this proportion decreased with increasing CD4 cell count in HIV-positive patients (test for trend p = 0.03. Low CD4 cell count (<300 cells/microl did not account for all QFT-IT indeterminate nor all negative results. Sensitivity when excluding indeterminate results was 86% (95% CI: 81-92% and did not differ between HIV-negative and HIV-positive patients (88 vs. 83%, p = 0.39. CONCLUSIONS/SIGNIFICANCE: Sensitivity of the QFT-IT for diagnosing active PTB infection was reasonable when excluding indeterminate results and in HIV-negative patients. However, since the test missed more than 10% of patients, its potential as a rule-out test for active TB disease is limited. Furthermore, test performance is impaired by low CD4 cell count in HIV-positive patients and possibly by other factors as well in both HIV-positive and HIV-negative patients. This might limit the potential of the test in populations where HIV-infection is prevalent.

  6. Methylated HBHA produced in M. smegmatis discriminates between active and non-active tuberculosis disease among RD1-responders.

    Directory of Open Access Journals (Sweden)

    Giovanni Delogu

    Full Text Available BACKGROUND: A challenge in tuberculosis (TB research is to develop a new immunological test that can help distinguish, among subjects responsive to QuantiFERON TB Gold In tube (QFT-IT, those who are able to control Mtb replication (remote LTBI, recent infection and past TB from those who cannot (active TB disease. IFN-γ response to the Heparin-binding-hemagglutinin (HBHA of Mtb has been associated with LTBI, but the cumbersome procedures of purifying the methylated and immunological active form of the protein from Mtb or M. bovis Bacillus Calmette et Guerin (BCG have prevented its implementation in a diagnostic test. Therefore, the aim of the present study was to evaluate the IFN-γ response to methylated HBHA of Mtb produced in M. smegmatis (rHBHAms in individuals at different stages of TB who scored positive to QFT-IT. METHODOLOGY/PRINCIPAL FINDINGS: 87 individuals at different stages of TB who scored positive to QFT-IT were selected. IFN-γ response to in vitro whole blood stimulation with rHBHAms was evaluated by short-term and long-term tests and detected by ELISA or flow cytometry. We demonstrated that the IFN-γ response to rHBHAms is mediated by CD4(+ T-cells with an effector-memory phenotype. This response, evaluated by short-term-tests, is significantly lower in active TB than in remote LTBI (p = 0.0010 and past TB (p = 0.0152. These results were confirmed by long-term tests. The qualitative data confirmed that IFN-γ responses higher than the cut-off point identified by ROC analysis are associated with the status of non-active disease. CONCLUSIONS: In this study we show that the T-cell response to a recombinant and methylated HBHA of Mtb produced in M. smegmatis is useful to discriminate between active and non-active TB disease among those responsive to QFT-IT in a whole blood system. Further studies are needed to improve the accuracy of the assay.

  7. Higher frequency of T-cell response to M. tuberculosis latency antigen Rv2628 at the site of active tuberculosis disease than in peripheral blood.

    Directory of Open Access Journals (Sweden)

    Teresa Chiacchio

    Full Text Available RATIONALE: Due to the invasive nature of the procedures involved, most studies of Mycobacterium tuberculosis (Mtb-specific immunity in humans have focused on the periphery rather than the site of active infection, the lung. Recently, antigens associated with Mtb-latency and -dormancy have been described using peripheral blood (PB cells; however their response in the lung is unknown. The objective of this report was to evaluate, in patients prospectively enrolled with suspected active tuberculosis (TB, whether the latency antigen Rv2628 induces local-specific immune response in bronchoalveolar lavage (BAL cells compared to PB cells. MATERIAL/METHODS: Among the 41 subjects enrolled, 20 resulted with active TB. Among the 21 without active disease, 9 were defined as subjects with latent TB-infection (LTBI [Quantiferon TB Gold In-tube positive]. Cytokine responses to Rv2628 were evaluated by enzyme linked immunospot (ELISPOT assay and flow cytometric (FACS analysis. RD1-secreted antigen stimulation was used as control. RESULTS: There was a significantly higher frequency of Rv2628- and RD1-specific CD4+ T-cells in the BAL of active TB patients than in PB. However the trend of the response to Rv2628 in subjects with LTBI was higher than in active TB in both PB and BAL, although this difference was not significant. In active TB, Rv2628 and RD1 induced a cytokine-response profile mainly consisting of interferon (IFN-γ-single-positive over double-IFN-γ/interleukin (IL-2 T-cells in both PB and BAL. Finally, BAL-specific CD4+ T-cells were mostly effector memory (EM, while peripheral T-cell phenotypes were distributed among naïve, central memory and terminally differentiated effector memory T-cells. CONCLUSIONS: In this observational study, we show that there is a high frequency of specific T-cells for Mtb-latency and RD1-secreted antigens (mostly IFN-γ-single-positive specific T-cells with an EM phenotype in the BAL of active TB patients. These data may

  8. Different screening strategies (single or dual for the diagnosis of suspected latent tuberculosis: a cost effectiveness analysis

    Directory of Open Access Journals (Sweden)

    Rook Graham

    2010-02-01

    Full Text Available Abstract Background Previous health economic studies recommend either a dual screening strategy [tuberculin skin test (TST followed by interferon-γ-release assay (IGRA] or a single one [IGRA only] for latent tuberculosis infection (LTBI, the former largely based on claims that it is more cost-effective. We sought to examine that conclusion through the use of a model that accounts for the additional costs of adverse drug reactions and directly compares two commercially available versions of the IGRA: the Quantiferon-TB-Gold-In-Tube (QFT-GIT and T-SPOT.TB. Methods A LTBI screening model directed at screening contacts was used to perform a cost-effectiveness analysis, from a UK healthcare perspective, taking into account the risk of isoniazid-related hepatotoxicity and post-exposure TB (2 years post contact using the TST, QFT-GIT and T-SPOT.TB IGRAs. Results Examining costs alone, the TST/IGRA dual screening strategies (TST/T-SPOT.TB and TST/QFT-GIT; £162,387 and £157,048 per 1000 contacts, respectively cost less than their single strategy counterparts (T-SPOT.TB and QFT-GIT; £203,983 and £202,921 per 1000 contacts which have higher IGRA test costs and greater numbers of persons undergoing LTBI treatment. However, IGRA alone strategies direct healthcare interventions and costs more accurately to those that are truly infected. Subsequently, less contacts need to be treated to prevent an active case of TB (T-SPOT.TB and QFT-GIT; 61.7 and 69.7 contacts in IGRA alone strategies. IGRA single strategies also prevent more cases of post-exposure TB. However, this greater effectiveness does not outweigh the lower incremental costs associated with the dual strategies. Consequently, when these costs are combined with effectiveness, the IGRA dual strategies are more cost-effective than their single strategy counterparts. Comparing between the IGRAs, T-SPOT.TB-based strategies (single and dual; £39,712 and £37,206 per active TB case prevented

  9. Chemistry for oncotheranostic gold nanoparticles.

    Science.gov (United States)

    Trouiller, Anne Juliette; Hebié, Seydou; El Bahhaj, Fatima; Napporn, Teko W; Bertrand, Philippe

    2015-06-24

    This review presents in a comprehensive ways the chemical methods used to functionalize gold nanoparticles with focus on anti-cancer applications. The review covers the parameters required for the synthesis gold nanoparticles with defined shapes and sizes, method for targeted delivery in tumours, and selected examples of anti-cancers compounds delivered with gold nanoparticles. A short survey of bioassays for oncology based on gold nanoparticles is also presented.

  10. ['Gold standard', not 'golden standard'

    NARCIS (Netherlands)

    Claassen, J.A.H.R.

    2005-01-01

    In medical literature, both 'gold standard' and 'golden standard' are employed to describe a reference test used for comparison with a novel method. The term 'gold standard' in its current sense in medical research was coined by Rudd in 1979, in reference to the monetary gold standard. In the same w

  11. ['Gold standard', not 'golden standard'

    NARCIS (Netherlands)

    Claassen, J.A.H.R.

    2005-01-01

    In medical literature, both 'gold standard' and 'golden standard' are employed to describe a reference test used for comparison with a novel method. The term 'gold standard' in its current sense in medical research was coined by Rudd in 1979, in reference to the monetary gold standard. In the same

  12. Comparison of screening procedures for Mycobacterium tuberculosis infection among patients with inflammatory diseases

    DEFF Research Database (Denmark)

    Soborg, Bolette; Ruhwald, Morten; Hetland, Merete Lund;

    2009-01-01

    OBJECTIVE: To test if Mycobacterium tuberculosis screening results differ among patients with inflammatory disease depending on whether the QuantiFeron TB-Gold test (QFT) or tuberculin skin test (TST) is used; and to evaluate if a possible difference is influenced by the presence of risk factors...... or immunosuppression. METHODS: The interferon-gamma response to in vitro stimulation of M. tuberculosis-specific antigens was measured with QFT and results were compared with TST. Associations to bacillus Calmette-Guerin (BCG) vaccination, risk factors, and immunosuppression were analyzed for both tests. RESULTS: QFT...... and TST results were available for 294/302 and 241/302 patients, respectively; 234 had results from both tests. Twenty-one (7%) tested positive with QFT and 45 (19%) with TST. A positive QFT was associated with risk factors for M. tuberculosis infection: i.e., birth or upbringing in a TB-endemic area...

  13. Tuberculosis Infection in Zambia: The Association with Relative Wealth

    Science.gov (United States)

    Boccia, Delia; Hargreaves, James; Ayles, Helen; Fielding, Katherine; Simwinga, Musonda; Godfrey-Faussett, Peter

    2013-01-01

    This study aimed to assess the association between household socioeconomic position and tuberculosis (TB) infection in two communities of Zambia. For this purpose we implemented a cross-sectional investigation, nested within a larger case control study. Infection was assessed using Quantiferon-TB Gold. A socioeconomic position index was constructed through principal component analysis combining data on human resources, food availability, housing quality, and access to services and infrastructures. In this study, higher socioeconomic position, rather than lower, was associated with significantly higher risk of TB infection. None of the traditional risk factors for TB infection mediated this association, suggesting that in these two communities TB transmission may occur through exposure to as yet undefined risk factors that are associated with higher socioeconomic position. Although further studies are needed, these results suggest emerging new patterns of TB transmission and a role of socioeconomic position on the risk of TB infection opposite to that expected. PMID:19478266

  14. Detecting a low prevalence of latent tuberculosis among health care workers in Denmark detected by M. tuberculosis specific IFN-gamma whole-blood test

    DEFF Research Database (Denmark)

    Soborg, Bolette; Andersen, Aase B; Larsen, Helle K;

    2007-01-01

    The study was designed to estimate prevalence of tuberculosis infection among health care workers, using the tuberculin skin test (TST) and the new M. tuberculosis specific diagnostic whole-blood test and to identify possible risk factors. Employees at 2 departments of infectious diseases...... TST whereas only 2 of 139 (1%) had a positive QuantiFERON TB-Gold test (QFT-TB). 42 of 106 (40%) BCG vaccinated had positive TST (> or =12 mm) compared with 2 of 27 (7%) unvaccinated persons. Among 47 persons with positive TST, 42 (89%) were BCG- vaccinated. The 2 QFT-TB positive participants as well...... and not to infection with M. tuberculosis. The overall transmission rate determined by QFT-TB was found to be very low. The QFT-TB may be useful in distinguishing persons with latent TB infection from persons with positive TST due to BCG vaccination and its use may reduce anxiety....

  15. Digging for Gold

    Science.gov (United States)

    Waters, John K.

    2012-01-01

    In the case of higher education, the hills are more like mountains of data that "we're accumulating at a ferocious rate," according to Gerry McCartney, CIO of Purdue University (Indiana). "Every higher education institution has this data, but it just sits there like gold in the ground," complains McCartney. Big Data and the new tools people are…

  16. GOLD PRESSURE VESSEL SEAL

    Science.gov (United States)

    Smith, A.E.

    1963-11-26

    An improved seal between the piston and die member of a piston-cylinder type pressure vessel is presented. A layer of gold, of sufficient thickness to provide an interference fit between the piston and die member, is plated on the contacting surface of at least one of the members. (AEC)

  17. Gold Nanoparticle Microwave Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, Kelsie E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Christian, Jonathan H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Coopersmith, Kaitlin [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Washington, II, Aaron L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Murph, Simona H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-07-27

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however, polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, and a reduction in reaction time from 10 minutes to 1 minute; this maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  18. Digging for Gold

    Science.gov (United States)

    Waters, John K.

    2012-01-01

    In the case of higher education, the hills are more like mountains of data that "we're accumulating at a ferocious rate," according to Gerry McCartney, CIO of Purdue University (Indiana). "Every higher education institution has this data, but it just sits there like gold in the ground," complains McCartney. Big Data and the new tools people are…

  19. Gold Nanoparticle Microwave Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, Kelsie E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Christian, Jonathan H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Coopersmith, Kaitlin [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Washington, II, Aaron L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Murph, Simona H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-07-27

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, a reduction in reaction time from 10 minutes to 1 minute, maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  20. Aiming for Gold

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Twenty-three years ago he claimed China’s first Olympic gold medal,with a win in the 50-meter pistol shooting competition.Now Xu Haifeng is leading the country’s modern pentathlon team in its bid for success at the Beijing Games

  1. Gold and gold working in Late Bronze Age Northern Greece

    Science.gov (United States)

    Vavelidis, M.; Andreou, S.

    2008-04-01

    Numerous objects of gold displaying an impressive variety of types and manufacturing techniques are known from the Late Bronze Age (LBA) contexts of Mycenaean Greece, but very little is known about the origin and processing of gold during the second millennium b.c. Ancient literature and recent research indicate that northern Greece is probably the richest gold-bearing region in Greece, and yet, very little evidence exists regarding the exploitation of its deposits and the production as well as use of gold in the area during prehistory. The unusual find of a group of small stone crucibles at the prehistoric settlement of Thessaloniki Toumba, one with visible traces of gold melting, proves local production and offers a rare opportunity to examine the process of on-site gold working. Furthermore, the comparison of the chemical composition of prehistoric artefacts from two settlements with those of gold deposits in their immediate areas supports the local extraction of gold and opens up the prospect for some of the Mycenaean gold to have originated in northern Greece. The scarcity of gold items in northern Greek LBA contexts may not represent the actual amount of gold produced and consumed, but could be a result of the local social attitudes towards the circulation and deposition of artefacts from precious metals.

  2. Flow in Tubes of Non-Circular Cross-Sections

    Science.gov (United States)

    Quadir, Raushan Ara

    In this thesis steady, laminar, viscous, incompressible flow in tubes of non-circular cross sections is investigated. The specific aims of the investigation are (a) to look at the problems of both developing flow and fully developed flow, (b) to consider non-circular cross sections in a more systematic manner than has been done in the past, and (c) to develop a relatively simple finite element technique for producing accurate numerical solutions of flow in tubes of fairly arbitrary cross sections. Fully developed flow in tubes is governed by a Poisson type equation for the mainstream velocity. Both analytical and numerical solutions are considered. The cross sections studied include elliptic and rectangular cross sections of different aspect ratios, some triangular cross sections, and a series of crescent-shaped cross sections. The physical characteristics of the flow are examined in a systematic manner in order to determine how these characteristics are affected by certain geometrical features of the cross section. Solutions fall into three basic categories depending on the shape of the cross section. In the first category, which includes circular and elliptic cross sections, solutions are possible in closed form. In the second, including rectangular and some triangular cross sections, solutions are in the form of infinite series. In the third, including cross sections of more complicated or irregular shapes, only numerical solutions are possible. Results of calculations of velocity profiles, flow rate, pumping power, and friction factor are presented in a way which can be useful for engineering applications. In numerical studies of both developing and fully developed flow finite element techniques are used. Results are obtained for tubes of rectangular and elliptic cross sections of different aspect ratios, for tubes of crescent -shaped cross sections and a tube whose cross section is an oval of Cassini. For fully developed flow, results are compared with the

  3. Developments in the flow of complex fluids in tubes

    CERN Document Server

    Siginer, Dennis A

    2015-01-01

    This book is dedicated to the tube flow of viscoelastic fluids and Newtonian single and multi-phase particle-laden fluids. This succinct volume collects the most recent analytical developments and experimental findings, in particular in predicting the secondary field, highlighting the historical developments which led to the progress made. This book brings a fresh and unique perspective and covers and interprets efforts to model laminar flow of viscoelastic fluids in tubes and laminar and turbulent flow of single and multi-phase particle-laden flow of linear fluids in light of the latest findings. This book also: Presents a thorough account of successes and failures in modeling and predicting tube flow of viscoelastic fluids and concentrated particle-laden flow of Newtonian fluids with specific explanations throughout Emphasizes the most up-to-date challenges in the field without requiring the reader to wade through detailed treatment of various theories Bridges the latest research results and established kno...

  4. Spiky gold nanoshells.

    Science.gov (United States)

    Sanchez-Gaytan, Brenda L; Park, So-Jung

    2010-12-21

    We report a high-yield synthetic method for a new type of metal nanostructure, spiky gold nanoshells, which combine the morphological characteristics of hollow metal nanoshells and nanorods. Our method utilizes block copolymer assemblies and polymer beads as templates for the growth of spiky nanoshells. Various shapes of spiky metal nanoshells were prepared in addition to spherical nanoshells by using block copolymer assemblies such as rod-like micelles, vesicles, and bilayers as templates. Furthermore, spiky gold shells encapsulating magnetic nanoparticles or quantum dots were prepared based on the ability of block copolymers to self-assemble with various types of nanoparticles and molecules. The capability to encapsulate other materials in the core, the shape tunability, and the highly structured surface of spiky nanoshells should benefit a range of imaging, sensing, and medical applications of metal nanostructures.

  5. Gold induced apoptsis study

    DEFF Research Database (Denmark)

    Laustsen, Christoffer

    2008-01-01

    at the moment, especially in the fields of lasers, they though have some problems concerning the placement of the tumor in the human body. Local heating by MR has tremendous advance in comparison too lasers. The first step is to validate the hypothesis of the inductive heating of the gold nano particles trough......Introduction   Cancer cells are highly thermo sensitive. On the basis of an article in Nature the idea arose, for a new non-invasive thermotherapy technique, based on radio frequency inductive heating of nano gold particles in an MR-scanner. Thermotherapy is getting considerably attention...... the low energy radio frequencies. If the method is demonstrated to be feasible, next step is testing in cell line trials.   Confocal microscopy experiments on cells are very hard to do reliable and reproducible statistic on, due to the fact that that it’s user counting which makes the data. Automatic...

  6. The RHIC gold rush

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, T. [Department of Physics, North Carolina State University (United States)

    2003-06-01

    Physicists are colliding gold nuclei to recreate the fireball that existed in the very early universe, and they may have found evidence for quark-gluon plasma. What happens to ordinary matter as you heat it to higher and higher temperatures, or compress it to greater and greater densities? This simple question underpins a major effort to create extreme conditions in the lab, which has recently taken the shape of the Relativistic Heavy Ion Collider (RHIC). This machine has been colliding gold nuclei since 2000, and has produced tantalizing hints that a new state of matter - the quark-gluon plasma - is created in the reactions. But it has also sparked surprises that are sending researchers back to the drawing board. (U.K.)

  7. The RHIC gold rush

    CERN Document Server

    Schäfer, T

    2003-01-01

    Physicists are colliding gold nuclei to recreate the fireball that existed in the very early universe, and they may have found evidence for quark-gluon plasma. What happens to ordinary matter as you heat it to higher and higher temperatures, or compress it to greater and greater densities? This simple question underpins a major effort to create extreme conditions in the lab, which has recently taken the shape of the Relativistic Heavy Ion Collider (RHIC). This machine has been colliding gold nuclei since 2000, and has produced tantalizing hints that a new state of matter - the quark-gluon plasma - is created in the reactions. But it has also sparked surprises that are sending researchers back to the drawing board. (U.K.)

  8. Diagnostic utility of QuantiFERON–TB Gold In-Tube test in pediatric tuberculosis disease in Taiwanese children

    Directory of Open Access Journals (Sweden)

    Kin-Sun Wong

    2017-06-01

    Conclusion: QFG-IT assay was more sensitive for the diagnosis of TB disease than TST in an intermediate burden population with universal neonatal BCG vaccination. The increased recognition of BCG induced osteitis in recent years has alerted physicians that BCG induced lesions should be suspected when TST is positive but QFG-IT is negative. Despite higher costs for QFG-IT than TST, they have additional value for the diagnosis of active TB and should be performed when a diagnosis of TB remains in doubt.

  9. Serial QuantiFERON-TB Gold In-Tube testing for psoriatic patients receiving antitumor necrosis factor-alpha therapy

    Directory of Open Access Journals (Sweden)

    Chun-Yu Cheng

    2015-09-01

    Conclusion: This study demonstrated that 14.29% of psoriatic patients undergoing long-term TNF-α antagonist therapy had a QFT-GIT conversion. Although a decreased IFN-γ level and QFT-GIT reversion were observed in most cases following prophylactic therapy, the value of QFT-GIT for evaluating the effect of LTBI prophylaxis remains controversial.

  10. Film Ace Takes Gold

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    "Really, I never, never expected to win this," said Chinese director Jia Zhangke on hearing he had taken the top award for his movie Still Life (Sanxia Haoren) at the Venice Film Festival, on September 9. A surprise late entry, Still Life quickly emerged as the favorite and the Gold Lion was again hugged by Chinese. The well-known Chinese director Zhang Yimou won the same award back in 1999, for Not One Less-also a

  11. JUNK: rubbish to gold

    OpenAIRE

    Hanson, Maria

    2015-01-01

    JUNK: rubbish to gold is a playful exploration of community economies (exchange, giving, bartering, gathering, earning, harvesting); putting on display the process of creating the ‘work of art’. Co-created and co-curated by Jivan Astfalck, Laura Bradshaw-Heap and Rachel Darbourne and partnered with charities, who supplied JUNK jewellery. During a public performance 31 jewellers ‘gifted’ their skills, (re)constructing pieces selected from a mountain of JUNK creating reimagined artworks for the...

  12. Rushing for gold

    DEFF Research Database (Denmark)

    Jønsson, Jesper Bosse; Bryceson, Deborah Fahy

    2009-01-01

    African rural dwellers have faced depressed economic prospects for several decades. Now, in a number of mineral-rich countries, multiple discoveries of gold and precious stones have attracted large numbers of prospective small-scale miners. While their 'rush' to, and activities within, mining sit...... affluent than the others, suggesting that movement can be rewarding for those willing to 'try their luck' with the hard work and social networking demands of mining another site....

  13. Gold-gold junction electrodes:the disconnection method.

    Science.gov (United States)

    Dale, Sara E C; Vuorema, Anne; Ashmore, Ellen M Y; Kasprzyk-Horden, Barbara; Sillanpää, Mika; Denuault, Guy; Marken, Frank

    2012-02-01

    The formation of gold-gold junction electrodes for application in electroanalysis is described here based on electro-deposition from a non-cyanide gold plating bath. Converging growth of two hemispherical gold deposits on two adjacent platinum microelectrodes (both 100 µm diameter in glass, ca. 45 µm gap) followed by careful etching in aqueous chloride solution was employed. During growth both gold hemispheres "connect" and during etching "disconnection" is evident in a drop in current. Gold-gold junctions with sub-micron gaps are formed and applied for the electroanalytical detection of sub-micromolar concentrations of hydroquinone in 0.1 M phosphate buffer pH 7 (E(rev) = 0.04 V vs. SCE) and sub-micromolar concentration of dopamine in 0.1 M phosphate buffer pH 7 (E(rev) = 0.14 V vs. SCE). The potential future uses in analysis and limitations of gold-gold junction electrodes are discussed.

  14. Green Synthesis of Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Hamid Reza Ghorbani

    2015-03-01

    Full Text Available There is an increased interest in understanding the toxicity and rational design of gold nanoparticles for biomedical applications in recent years. In this study gold nanoparticles were synthesized using dextrose as a reducing agent. The gold nanoparticles displayed characteristic Surface Plasmon Resonance peak at around 550 nm having a mean particle size of 75±30 nm. In order to identify and analyze nanoparticles, UV–Vis spectroscopy, Scanning electron microscopy (SEM, and dynamic light scattering (DLS were used.

  15. The extractive metallurgy of gold

    Science.gov (United States)

    Kongolo, K.; Mwema, M. D.

    1998-12-01

    Mössbauer spectroscopy has been successfully used in investigation of the gold compounds present in ores and the gold species which occur during the process metallurgy of this metal. This paper is a survey of the basic recovery methods and techniques used in extractive metallurgy of gold. Process fundamentals on mineral processing, ore leaching, zinc dust cementation, adsorption on activated carbon, electrowinning and refining are examined. The recovery of gold as a by-product of the copper industry is also described. Alternative processing methods are indicated in order to shed light on new interesting research topics where Mössbauer spectroscopy could be applied.

  16. Social Determinants of Pulmonary Tuberculosis in Families of Migrants participating in Mexico-Canada Seasonal Agricultural Workers Program: A Study in Guadalupe Zaragoza

    Directory of Open Access Journals (Sweden)

    Rodolfo Gines Martínez Fernández

    2010-04-01

    Full Text Available Objective: To analyze the social determinants of pulmonary tuberculosis in the families of migrant laborers registered in the Seasonal Agricultural Workers Program (SAWP and residing in Guadalupe Zaragoza Tlahuapan, Puebla, México. Methods: An exploratory cross-sectional study of the interaction between migration, social determinants, and pulmonary tuberculosis. Results: In this poor and patriarchal community, the SAWP offers financial opportunities for the men of Guadalupe Zaragoza. The remittances of these migrant workers have enabled their families to live in adequate housing, but their health situation is still vulnerable. Only half of the families have access to public health services or the special health programs for migrant worker families. 13% of migrant family members were infected with pulmonary tuberculosis as measured by the Quantiferon-TB test. The female partners of migrants typically do not study past elementary school, become housewives with no pay, are forced to take on added work in the household, and experience subjective symptoms of stress and fatigue. The children of Guadalupe Zaragoza are also vulnerable; the number of children in this community who can regularly attend school is below the national average because many children have to work. These families end up paying more for education, housing, and health services than the average Mexican family. Conclusions: In the families of SAWP migrant workers, the prevalence of latent pulmonary tuberculosis was found to be lower than the national average based on studies using the tuberculin test; this may be due to the greater specificity of the Quantiferon-TB Gold test. There is a significant risk of reactivation tuberculosis in these families due to the inequity in the social determinants of health.

  17. Turning lead into gold

    DEFF Research Database (Denmark)

    Jensen, Steffen Moltrup Ernø

    For years the field of entrepreneurship has been blinded by the alchemical promise of turning lead into gold, of finding the ones most likely to become the next Branson, Zuckerberg or Gates. The promise has been created in the midst of political and scientific agendas where certain individuals...... is not to accumulate state or market wealth, but for entrepreneurial skills to become tools towards the liberation of the individual from oppressive systems of control – essentially to add public value rather than economic value. In this presentation I will sketch an anarchist perspective on entrepreneurship, looking...

  18. Gold electrodes from recordable CDs

    Science.gov (United States)

    Angnes; Richter; Augelli; Kume

    2000-11-01

    Gold electrodes are widely used in electrochemistry and electroanalytical chemistry. The notable performance when used in stripping analysis of many ionic species and the extraordinary affinity of thio compounds for its surface make these electrodes very suitable for many applications. This paper reports a simple and novel way to construct gold electrodes (CDtrodes) using recordable CDs as the gold source. The nanometer thickness of the gold layer of recordable disks (50-100 nm) favors the construction of band nanoelectrodes with areas as small as 10(-6) cm2. The plane surface can be easily used for the construction of conventional-sized gold electrodes for batch or flow injection analysis or even to obtain electrodes as large as 100 cm2. The low price of commercial recordable CDs allows a "one way use". The evaluation and applicability of these electrodes in the form of nanoelectrodes, in batch and associated with flow cells, are illustrated in this paper.

  19. Directed Assembly of Gold Nanoparticles

    DEFF Research Database (Denmark)

    Westerlund, Axel Rune Fredrik; Bjørnholm, Thomas

    2009-01-01

    As a complement to common "top-down" lithography techniques, "bottom-up" assembly techniques are emerging as promising tools to build nanoscale structures in a predictable way. Gold nanoparticles that are stable and relatively easy to synthesize are important building blocks in many such structures...... due to their useful optical and electronic properties. Programmed assembly of gold nanoparticles in one, two, and three dimensions is therefore of large interest. This review focuses on the progress from the last three years in the field of directed gold nanoparticle and nanorod assembly using...

  20. GOLD and the fixed ratio

    Directory of Open Access Journals (Sweden)

    Vestbo J

    2012-09-01

    Full Text Available Jørgen VestboUniversity of Manchester, Manchester, UKI read with interest the paper entitled "Diagnosis of airway obstruction in the elderly: contribution of the SARA study" by Sorino et al in a recent issue of this journal.1 Being involved in the Global Initiative for Obstructive Lung Diseases (GOLD, it is nice to see the interest sparked by the GOLD strategy document. However, in the paper by Sorino et al, there are a few misunderstandings around GOLD and the fixed ratio (forced expiratory volume in 1 second/forced volume vital capacity < 0.70 that need clarification.View original paper by Sorino and colleagues.

  1. 41 CFR 101-45.002 - Gold.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Gold. 101-45.002 Section... PERSONAL PROPERTY § 101-45.002 Gold. (a) Gold will be sold in accordance with this section and part 102-38 of the Federal Management Regulation. (b) Sales of gold shall be processed to— (1) Use the sealed bid...

  2. 20th-Century Gold Rush.

    Science.gov (United States)

    Wargo, Joseph G.

    1992-01-01

    Presents Nevada's gold rush activities spurred by technological advancements in search methods. Describes the events that led to the twentieth-century gold rush, the techniques for finding deposits and the geological formation process of disseminated gold deposits. Vignettes present the gold extraction process, cross-section, and profile of a…

  3. Protein-mediated autoreduction of gold salts to gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Nivedita; Bhattacharya, Resham; Mukherjee, Priyabrata [Department of Biochemistry and Molecular Biology, College of Medicine, Mayo Clinic, Rochester, MN 55905 (United States)], E-mail: Mukherjee.Priyabrata@mayo.edu

    2008-09-01

    Here we report for the first time that proteins can function as unique reducing agents to produce gold nanoparticles from gold salts. We demonstrate that three different proteins, namely, bovine serum albumin (BSA), Rituximab (RIT-an anti-CD20 antibody) and Cetuximab (C225-anti-EGFR antibody), reduce gold salts to gold nanoparticles (GNP). Interestingly, among all the three proteins tested, only BSA can reduce gold salts to gold nanotriangles (GNT). BSA-induced formation of GNT can be controlled by carefully selecting the reaction condition. Heating or using excess of ascorbic acid (AA) as additional reducing agent shifts the reaction towards the formation of GNP with flower-like morphology, whereas slowing down the reaction either by cooling or by adding small amount of AA directs the synthesis towards GNT formation. GNT is formed only at pH 3; higher pHs (pH 7 and pH 10) did not produce any nanoparticles, suggesting the involvement of specific protein conformation in GNT formation. The nanomaterials formed by this method were characterized using UV-visible (UV-vis) spectroscopy and transmission electron microscopy (TEM). This is an important finding that will have uses in various nanotechnological applications, particularly in the green synthesis of novel nanomaterials based on protein structure.

  4. Metallic gold beads in hyaluronic acid

    DEFF Research Database (Denmark)

    Pedersen, Dan Sonne; Tran, Thao Phuong; Smidt, Kamille;

    2013-01-01

    by exploiting macrophage-induced liberation of gold ions (dissolucytosis) from gold surfaces. Injecting gold beads in hyaluronic acid (HA) as a vehicle into the cavities of the brain can delay clinical signs of disease progression in the MS model, experimental autoimmune encephalitis (EAE). This study....... In conclusion, our findings support that bio-liberation of gold from metallic gold surfaces have anti-inflammatory properties similar to classic gold compounds, warranting further studies into the pharmacological potential of this novel gold-treatment and the possible synergistic effects of hyaluronic acid....

  5. Gold-Catalyzed Synthesis of Heterocycles

    Science.gov (United States)

    Arcadi, Antonio

    2014-04-01

    The following sections are included: * Introduction * Synthesis of Heterocycles via Gold-Catalyzed Heteroatom Addition to Unsaturated C-C Bonds * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Cyclization of Polyunsaturated Compounds * Synthesis of Heterocyclic Compounds via α-Oxo Gold Carbenoid * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Cycloaddition Reactions * Synthesis of Heterocyclic Derivatives through Gold-Catalyzed Activation of Carbonyl Groups and Alcohols * Synthesis of Heterocyclic Compounds through Gold-Mediated C-H Bond Functionalization * Gold-Catalyzed Domino Cyclization/Oxidative Coupling Reactions * Conclusions * References

  6. Gold island fiber optic sensor

    Science.gov (United States)

    Meriaudeau, Fabrice; Wig, A. G.; Passian, A.; Downey, Todd R.; Buncick, Milan; Ferrell, Trinidad L.

    1999-12-01

    A fiber optic chemical sensor based on gold-island surface plasmon excitation is presented. The sensing part of the fiber is the end of the fiber onto which a thin layer of gold has been deposited to form a particulate surface. Annealing the gold reshapes the particles and produces an optical absorbance near 535 nm with the fiber in air. The optical absorption resonance of the gold particles is shifted if the fiber is immersed in a medium other than air. These resonance shifts are examined by transmission spectroscopy through the fiber. Experimental results for the sensitivity and dynamic range in the measurement of liquid solutions are in agreement with a basic theoretical model which characterizes the surface plasmon using nonretarded electrodynamics.

  7. Biomass processing over gold catalysts

    CERN Document Server

    Simakova, Olga A; Murzin, Dmitry Yu

    2014-01-01

    The book describes the valorization of biomass-derived compounds over gold catalysts. Since biomass is a rich renewable feedstock for diverse platform molecules, including those currently derived from petroleum, the interest in various transformation routes has become intense. Catalytic conversion of biomass is one of the main approaches to improving the economic viability of biorefineries.  In addition, Gold catalysts were found to have outstanding activity and selectivity in many key reactions. This book collects information about transformations of the most promising and important compounds derived from cellulose, hemicelluloses, and woody biomass extractives. Since gold catalysts possess high stability under oxidative conditions, selective oxidation reactions were discussed more thoroughly than other critical reactions such as partial hydrogenation, acetalization, and isomerization. The influence of reaction conditions, the role of the catalyst, and the advantages and disadvantages of using gold are pre...

  8. Gold, currencies and market efficiency

    Science.gov (United States)

    Kristoufek, Ladislav; Vosvrda, Miloslav

    2016-05-01

    Gold and currency markets form a unique pair with specific interactions and dynamics. We focus on the efficiency ranking of gold markets with respect to the currency of purchase. By utilizing the Efficiency Index (EI) based on fractal dimension, approximate entropy and long-term memory on a wide portfolio of 142 gold price series for different currencies, we construct the efficiency ranking based on the extended EI methodology we provide. Rather unexpected results are uncovered as the gold prices in major currencies lay among the least efficient ones whereas very minor currencies are among the most efficient ones. We argue that such counterintuitive results can be partly attributed to a unique period of examination (2011-2014) characteristic by quantitative easing and rather unorthodox monetary policies together with the investigated illegal collusion of major foreign exchange market participants, as well as some other factors discussed in some detail.

  9. Gold, coal and oil.

    Science.gov (United States)

    Dani, Sergio U

    2010-03-01

    Jared Diamond has hypothesized that guns, germs and steel account for the fate of human societies. Here I propose an extension of Diamond's hypothesis and put it in other terms and dimensions: gold, coal and oil account not only for the fate of human societies but also for the fate of mankind through the bodily accumulation of anthropogenic arsenic, an invisible weapon of mass extinction and evolutionary change. The background is clear; arsenic species fulfill seven criteria for a weapon of mass extinction and evolutionary change: (i) bioavailability to all living organisms; (ii) imperceptibility; (iii) acute toxicity; (iv) bioaccumulation and chronic toxicity; (v) adverse impact on reproductive fitness and reproductive outcomes and early-age development and growth in a wide range of microbial, plant and animal species including man; (vi) widespread geographical distribution, mobility and ecological persistence on a centennial to millennial basis and (vii) availability in necessary and sufficient amounts to exert evolutionarily meaningful effects. The proof is becoming increasingly feasible as human exploitation of gold, coal and oil deposits cause sustainable rises of arsenic concentrations in the biosphere. Paradoxically, humans are among the least arsenic-resistant organisms because humans are long-lived, encephalized and complex social metazoans. An arsenic accumulation model is presented here to describe how arsenic accumulates in the human body with increasing age and at different provisionally safe exposure levels. Arsenic accumulates in the human body even at daily exposure levels which are within the lowest possible WHO provisional tolerance limits, yielding bodily arsenic concentrations which are above WHO provisional limits. Ongoing consequences of global scale arsenic poisoning of mankind include age-specific rises in morbidity and mortality followed by adaptive changes. The potential rise of successful forms of inborn resistance to arsenic in humans

  10. Gold-catalyzed domino reactions.

    Science.gov (United States)

    Michelet, Véronique

    2015-01-01

    Gold-catalyzed reactions have appeared to be highly attractive tools for chemists to promote novel transformations to prepare elaborated structures from simple starting materials. This chapter presents selected and original examples of domino processes in the presence of gold catalysts, highlighting reports implying hydration, hydroxylation, and hydroamination as key starting point for cascade transformations. Domino processes implying 1,n-enynes, asymmetric domino transformations, and applications of all the presented processes in total synthesis are presented.

  11. Gold nanoparticle (AuNPs) and gold nanopore (AuNPore) catalysts in organic synthesis.

    Science.gov (United States)

    Takale, Balaram S; Bao, Ming; Yamamoto, Yoshinori

    2014-04-07

    Organic synthesis using gold has gained tremendous attention in last few years, especially heterogeneous gold catalysis based on gold nanoparticles has made its place in almost all organic reactions, because of the robust and green nature of gold catalysts. In this context, gold nanopore (AuNPore) with a 3D metal framework is giving a new dimension to heterogeneous gold catalysts. Interestingly, AuNPore chemistry is proving better than gold nanoparticles based chemistry. In this review, along with recent advances, major discoveries in heterogeneous gold catalysis are discussed.

  12. Modeling of gold production in Malaysia

    Science.gov (United States)

    Muda, Nora; Ainuddeen, Nasihah Rasyiqah; Ismail, Hamizun; Umor, Mohd Rozi

    2013-04-01

    This study was conducted to identify the main factors that contribute to the gold production and hence determine the factors that affect to the development of the mining industry in Malaysia. An econometric approach was used by performing the cointegration analysis among the factors to determine the existence of long term relationship between the gold prices, the number of gold mines, the number of workers in gold mines and the gold production. The study continued with the Granger analysis to determine the relationship between factors and gold production. Results have found that there are long term relationship between price, gold production and number of employees. Granger causality analysis shows that there is only one way relationship between the number of employees with gold production in Malaysia and the number of gold mines in Malaysia.

  13. Monoclonal antibody "gold rush".

    Science.gov (United States)

    Maggon, Krishan

    2007-01-01

    The market, sales and regulatory approval of new human medicines, during the past few years, indicates increasing number and share of new biologics and emergence of new multibillion dollar molecules. The global sale of monoclonal antibodies in 2006 were $20.6 billion. Remicade had annual sales gain of $1 billion during the past 3 years and five brands had similar increase in 2006. Rituxan with 2006 sales of $4.7 billion was the best selling monoclonal antibody and biological product and the 6th among the top selling medicinal brand. It may be the first biologic and monoclonal antibody to reach $10 billion annual sales in the near future. The strong demand from cancer and arthritis patients has surpassed almost all commercial market research reports and sales forecast. Seven monoclonal antibody brands in 2006 had sales exceeding $1 billion. Humanized or fully human monoclonal antibodies with low immunogenicity, enhanced antigen binding and reduced cellular toxicity provide better clinical efficacy. The higher technical and clinical success rate, overcoming of technical hurdles in large scale manufacturing, low cost of market entry and IND filing, use of fully human and humanized monoclonal antibodies has attracted funds and resources towards R&D. Review of industry research pipeline and sales data during the past 3 years indicate a real paradigm shift in industrial R&D from pharmaceutical to biologics and monoclonal antibodies. The antibody bandwagon has been joined by 200 companies with hundreds of new projects and targets and has attracted billions of dollars in R&D investment, acquisitions and licensing deals leading to the current Monoclonal Antibody Gold Rush.

  14. Gold process mineralogy: Objectives, techniques, and applications

    Science.gov (United States)

    Zhou, Joe Y.; Cabri, Louis J.

    2004-07-01

    The extractive metallurgy of gold is largely driven by mineralogical factors such as gold particle size; association with other minerals; coatings; presence of cyanicides, oxygen consumers, and preg-robbers; presence of refractory gold minerals; and locking of submicroscopic gold in sulfide and sulfarsenide mineral structures. Gold process mineralogy addresses all issues related to gold ore processing by the detailed study of an ore or a mill product. The methodology is widely used as a predictive tool in feasibility studies and during the process development stage, and as a trouble-shooting tool for mineral processing and hydrometallurgical operations.

  15. Serum gold concentrations during treatment with auranofin.

    Science.gov (United States)

    Van Riel, P L; Gribnau, F W; Van de Putte, L B; Arts, C W; Van Aernsbergen, A

    1987-03-01

    Serum gold concentrations were measured in rheumatoid arthritis patients during chronic treatment with the orally adsorbable gold compound auranofin. In agreement with data in the literature, the highest serum gold concentration was reached after 16 weeks of treatment with 6 mg auranofin daily. A striking finding in this study was that thereafter the serum gold concentrations did not appear to plateau but declined gradually. Statistically this resulted in a significantly lower concentration after one year as compared with week 16 (p less than 0.05, paired t-test). It is suggested that a shift from protein bound gold to cell-bound gold might be the explanation.

  16. Phage based green chemistry for gold ion reduction and gold retrieval.

    Science.gov (United States)

    Setyawati, Magdiel I; Xie, Jianping; Leong, David T

    2014-01-22

    The gold mining industry has taken its toll on the environment, triggering the development of more environmentally benign processes to alleviate the waste load release. Here, we demonstrate the use of bacteriophages (phages) for biosorption and bioreduction of gold ions from aqueous solution, which potentially can be applied to remediate gold ions from gold mining waste effluent. Phage has shown a remarkably efficient sorption of gold ions with a maximum gold adsorption capacity of 571 mg gold/g dry weight phage. The product of this phage mediated process is gold nanocrystals with the size of 30-630 nm. Biosorption and bioreduction processes are mediated by the ionic and covalent interaction between gold ions and the reducing groups on the phage protein coat. The strategy offers a simple, ecofriendly and feasible option to recover of gold ions to form readily recoverable products of gold nanoparticles within 24 h.

  17. New Trends in Gold Catalysts

    Directory of Open Access Journals (Sweden)

    Leonarda F. Liotta

    2014-07-01

    Full Text Available Gold is an element that has fascinated mankind for millennia. The catalytic properties of gold have been a source of debate, due to its complete chemical inertness when in a bulk form, while it can oxidize CO at temperatures as low as ~200 K when in a nanocrystalline state, as discovered by Haruta in the late 1980s [1]. Since then, extensive activity in both applied and fundamental research on gold has been initiated. The importance of the catalysis by gold represents one of the fasted growing fields in science and is proven by the promising applications in several fields, such as green chemistry and environmental catalysis, in the synthesis of single-walled carbon nanotubes, as modifiers of Ni catalysts for methane steam and dry reforming reactions and in biological and electrochemistry applications. The range of reactions catalyzed by gold, as well as the suitability of different supports and the influence of the preparation conditions have been widely explored and optimized in applied research [2]. Gold catalysts appeared to be very different from the other noble metal-based catalysts, due to their marked dependence on the preparation method, which is crucial for the genesis of the catalytic activity. Several methods, including deposition-precipitation, chemical vapor deposition and cation adsorption, have been applied for the preparation of gold catalysts over reducible oxides, like TiO2. Among these methods, deposition-precipitation has been the most frequently employed method for Au loading, and it involves the use of tetrachloroauric (III acid as a precursor. On the other hand, the number of articles dealing with Au-loaded acidic supports is smaller than that on basic supports, possibly because the deposition of [AuCl4]− or [AuOHxCl4−x]− species on acidic supports is difficult, due to their very low point of zero charge. Despite this challenge, several groups have reported the use of acidic zeolites as supports for gold. Zeolites

  18. Nanobubble trouble on gold surfaces

    DEFF Research Database (Denmark)

    Holmberg, Maria; Kuhle, A.; Garnaes, J.

    2003-01-01

    When analyzing surfaces related to biosensors with in situ atomic force microscopy (AFM), the existence of nanobubbles called for our attention. The bubbles seem to form spontaneously when gold surfaces are immersed in clean water and are probably a general phenomenon at water-solid interfaces....... Besides from giving rise to undesired effects in, for example, biosensors, nanobubbles can also cause artifacts in AFM imaging. We have observed nanobubbles on unmodified gold surfaces, immersed in clean water, using standard silicon AFM probes. Nanobubbles can be made to disappear from contact mode AFM...

  19. Economic geology: Gold buried by oxygen

    OpenAIRE

    Gaillard, Fabrice; Copard, Y.

    2015-01-01

    International audience; he Witwatersrand Basin in South Africa contains extraordinary amounts of gold. Thermodynamic calculations suggest that the gold may have accumulated there in response to a perfect storm of conditions available only during the Archaean.

  20. Economic geology: Gold buried by oxygen

    OpenAIRE

    Gaillard, Fabrice; Copard, Y.

    2015-01-01

    International audience; he Witwatersrand Basin in South Africa contains extraordinary amounts of gold. Thermodynamic calculations suggest that the gold may have accumulated there in response to a perfect storm of conditions available only during the Archaean.

  1. 31 CFR 100.4 - Gold coin and gold certificates in general.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Gold coin and gold certificates in general. 100.4 Section 100.4 Money and Finance: Treasury Regulations Relating to Money and Finance EXCHANGE OF PAPER CURRENCY AND COIN In General § 100.4 Gold coin and gold certificates in general....

  2. Single-crystalline gold nanoplates from a commercial gold plating solution.

    Science.gov (United States)

    Li, Zhonghao; Lapeyre, Véronique; Ravaine, Valérie; Ravaine, Serge; Kuhn, Alexander

    2009-03-01

    A novel route was proposed to synthesize gold nanoplates using a commercial gold plating solution as the reactant. Single-crystalline gold nanoplates can be successfully synthesized by reacting gold plating solution with HCl. The as-prepared nanoplates are from several micrometers to tens of micrometers in size. The effects of reactant concentration and temperature on the morphology of the gold products were investigated. The size of the gold nanoplate increases with the decrease of the amount of gold plating solution, while irregular gold nanoparticles are formed as the HCl concentration becomes low. When the reaction temperature is as low as room temperature, nanoplates with a concavity form. Specifically, it is found that the Cl- plays an important role for the formation of these gold nanoplates. The formation mechanism of the gold nanoplates is studied in detail.

  3. Gold and Silver Extraction from Leach Solutions

    OpenAIRE

    Bagdaulet K. Kenzhaliyev; Renata R. Iskhakova; Zamzagul D. Dosymbaeva; Esen N. Sulejmenov

    2014-01-01

    There has been carried out an investigation on the extraction of gold and silver from thiosulfate solutions: standard test and technological solutions of chemical and electrochemical leaching. The influence of related metals on the process of extracting gold from solution was studied. There has been conducted a comparative study of the IR spectra of solutions after the sorption of gold, silver and related metals.

  4. Highly active thermally stable nanoporous gold catalyst

    Science.gov (United States)

    Biener, Juergen; Wittstock, Arne; Biener, Monika M.; Bagge-Hansen, Michael; Baeumer, Marcus; Wichmann, Andre; Neuman, Bjoern

    2016-12-20

    In one embodiment, a system includes a nanoporous gold structure and a plurality of oxide particles deposited on the nanoporous gold structure; the oxide particles are characterized by a crystalline phase. In another embodiment, a method includes depositing oxide nanoparticles on a nanoporous gold support to form an active structure and functionalizing the deposited oxide nanoparticles.

  5. CO oxidation on gold nanoparticles: Theoretical studies

    DEFF Research Database (Denmark)

    Remediakis, Ioannis; Lopez, Nuria; Nørskov, Jens Kehlet

    2005-01-01

    We present a summary of our theoretical results regarding CO oxidation on both oxide-supported and isolated gold nanoparticles. Using Density Functional Theory we have studied the adsorption of molecules and the oxidation reaction of CO on gold clusters. Low-coordinated sites on the gold...

  6. Highly active thermally stable nanoporous gold catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Biener, Juergen; Wittstock, Arne; Biener, Monika M.; Bagge-Hansen, Michael; Baeumer, Marcus; Wichmann, Andre; Neuman, Bjoern

    2016-12-20

    In one embodiment, a system includes a nanoporous gold structure and a plurality of oxide particles deposited on the nanoporous gold structure; the oxide particles are characterized by a crystalline phase. In another embodiment, a method includes depositing oxide nanoparticles on a nanoporous gold support to form an active structure and functionalizing the deposited oxide nanoparticles.

  7. Gold color in dental alloys.

    Science.gov (United States)

    Cameron, T

    1997-01-01

    This article will help the dental laboratory with alloy selection by exploring how the relationship among color, ductility and strength applies to gold and how color can be quantified. Because higher quality materials translate into higher profits, upselling to the dentist and patient is also discussed.

  8. Ultrafast vibrations of gold nanorings

    DEFF Research Database (Denmark)

    Kelf, T; Tanaka, Y; Matsuda, O

    2011-01-01

    We investigate the vibrational modes of gold nanorings on a silica substrate with an ultrafast optical technique. By comparison with numerical simulations, we identify several resonances in the gigahertz range associated with axially symmetric deformations of the nanoring and substrate. We...

  9. Gold, Silver and Bronze Citations.

    Science.gov (United States)

    American School & University, 2003

    2003-01-01

    Presents the gold, silver, and bronze winners of a competition, which judged the most outstanding learning environments at educational institutions nationwide. Jurors spent two days reviewing projects, focusing on concepts and ideas that made them exceptional. For each citation, the article offers information on the firm, client, total area, total…

  10. Optical trapping of gold aerosols

    DEFF Research Database (Denmark)

    Schmitt, Regina K.; Pedersen, Liselotte Jauffred; Taheri, S. M.

    2015-01-01

    Aerosol trapping has proven challenging and was only recently demonstrated.1 This was accomplished by utilizing an air chamber designed to have a minimum of turbulence and a laser beam with a minimum of aberration. Individual gold nano-particles with diameters between 80 nm and 200 nm were trappe...

  11. Powder-in-Tube (PIT) Nb3Sn conductors for high-field magnets

    NARCIS (Netherlands)

    Lindenhovius, J.H.; Hornsveld, E.M.; den Ouden, A.; Wessel, Wilhelm A.J.; ten Kate, Herman H.J.

    2000-01-01

    New Nb3Sn conductors, based on the powder-in-tube (PIT) process, have been developed for application in accelerator magnets and high-field solenoids. For application in accelerator magnets, SMI has developed a binary 504 filament PIT conductor by optimizing the manufacturing process and adjustment o

  12. PROGRESS IN PROCESS INTENSIFICATION: SYNTHESIS OF IMINES USING A SPINNING TUBE-IN-TUBE REACTOR

    Science.gov (United States)

    The high purity, high throughput synthesis of a number of imines (Schiff bases) using a spinning tube-in-tube reactor (STT, Kreido Laboratories, Camarillo, CA) has been carried out. The STT reactor allows the high throughput production of high purity imines from a wide variety of...

  13. EPOXIDATION OF SMALL ORGANIC MOLECULES USING A SPINNING TUBE-IN-TUBE REACTOR

    Science.gov (United States)

    The commodity-scale epoxidation of several organic molecules has been carried out using a Spinning Tube-in-Tube (STTr) reactor (manufactured by Kreido Laboratories). This reactor, which embodies and facilitates the use of Green Chemistry principles and Process Intensification, a...

  14. PROGRESS IN PROCESS INTENSIFICATION: SYNTHESIS OF IMIDAZOLE DERIVATIVES USING A SPINNING TUBE-IN-TUBE REACTOR

    Science.gov (United States)

    The high purity, high throughput synthesis of a number of imidazole derivatives using a spinning tube-in-tube reactor (STT®, Kreido Laboratories, Camarillo California) has been carried out. The STT® reactor allows the high throughput production of high purity imidazole derivativ...

  15. PROGRESS IN PROCESS INTENSIFICATION: SYNTHESIS OF IMIDAZOLE DERIVATIVES USING A SPINNING TUBE-IN-TUBE REACTOR

    Science.gov (United States)

    The high purity, high throughput synthesis of a number of imidazole derivatives using a spinning tube-in-tube reactor (STT®, Kreido Laboratories, Camarillo California) has been carried out. The STT® reactor allows the high throughput production of high purity imidazole derivativ...

  16. PROGRESS IN PROCESS INTENSIFICATION: SYNTHESIS OF IMINES USING A SPINNING TUBE-IN-TUBE REACTOR

    Science.gov (United States)

    The high purity, high throughput synthesis of a number of imines (Schiff bases) using a spinning tube-in-tube reactor (STT, Kreido Laboratories, Camarillo, CA) has been carried out. The STT reactor allows the high throughput production of high purity imines from a wide variety of...

  17. EPOXIDATION OF SMALL ORGANIC MOLECULES USING A SPINNING TUBE-IN-TUBE REACTOR

    Science.gov (United States)

    The commodity-scale epoxidation of several organic molecules has been carried out using a Spinning Tube-in-Tube (STTr) reactor (manufactured by Kreido Laboratories). This reactor, which embodies and facilitates the use of Green Chemistry principles and Process Intensification, a...

  18. Powder-in-Tube (PIT) Nb3Sn conductors for high-field magnets

    NARCIS (Netherlands)

    Lindenhovius, J.H.; Hornsveld, E.M.; den Ouden, A.; Wessel, Wilhelm A.J.; ten Kate, Herman H.J.

    2000-01-01

    New Nb3Sn conductors, based on the powder-in-tube (PIT) process, have been developed for application in accelerator magnets and high-field solenoids. For application in accelerator magnets, SMI has developed a binary 504 filament PIT conductor by optimizing the manufacturing process and adjustment

  19. Gold nephropathy in juvenile rheumatoid arthritis.

    Science.gov (United States)

    Husserl, F E; Shuler, S E

    1979-01-01

    A 2-year-old girl was treated with gold salts for juvenile rheumatoid arthritis. Treatment had to be discontinued when persistent proteinuria was detected. As this case report indicates, close monitoring of the urine is mandatory during treatment with gold salts to detect early signs of toxicity: hematuria followed by casts and then proteinuria as therapy is continued. Histologic examination with electron microscopy will help to differentiate the different forms of gold toxicity. When the findings are consistent with gold-induced renal involvement, therapy should be discontinued. The gold nephropathy usually resolves in time, with no permanent renal damage.

  20. Hydrofluorination of Alkynes Catalysed by Gold Bifluorides

    OpenAIRE

    Nahra, Fady; Patrick, Scott R.; Bello, Davide; Brill, Marcel; Obled, Alan; Cordes, David B.; Slawin, Alexandra M. Z.; O'Hagan, David; Steven P. Nolan

    2014-01-01

    We report the synthesis of nine new N-heterocyclic carbene gold bifluoride complexes starting from the corresponding N-heterocyclic carbene gold hydroxides. A new methodology to access N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene gold(I) fluoride starting from N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene gold(I) hydroxide and readily available potassium bifluoride is also reported. These gold bifluorides were shown to be efficient catalysts in the hydrofluorination of symmetrical an...

  1. I. Unbound serum gold: procedure for quantitation.

    Science.gov (United States)

    Lorber, A; Vibert, G J; Harralson, A F; Simon, T M

    1983-08-01

    The unbound fraction of many drugs appears to be the therapeutically active component. However, the major problem encountered in following unbound serum gold (UBSG) concentration during chrysotherapy has been the ability to quantitate such a small quantity of gold reliably without matrix interference. The methodology detailed here overcomes these difficulties and provides an effective means of monitoring the UBSG fraction during chrysotherapy. We have observed that the unbound fraction of gold dissipates quickly after gold sodium thiomalate administration and constitutes less than 2% of the total serum gold concentration.

  2. Gold recycling; a materials flow study

    Science.gov (United States)

    Amey, Earle B.

    2000-01-01

    This materials flow study includes a description of trends in consumption, loss, and recycling of gold-containing materials in the United States in 1998 in order to illustrate the extent to which gold is presently being recycled and to identify recycling trends. The quantity of gold recycled, as a percent of the apparent supply of gold, was estimated to be about 30 percent. Of the approximately 446 metric tons of gold refined in the United States in 1998, the fabricating and industrial use losses were 3 percent.

  3. New approach to fabricate nanoporous gold film

    Institute of Scientific and Technical Information of China (English)

    Hui Zhou; Lan Jin; Wei Xu

    2007-01-01

    A simple preparation of ultrathin nanoporous gold film was described. Copper and gold were used to fabricate Cu-Au alloy films through vacuum deposition. The formation of nanoporous gold films from the alloy films involved thermal process and chemical etch by hydrochloric acid or by nitric acid. The free-standing nanoporous gold films have been analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS) and surface-enhanced Raman scattering (SERS). It was noted that the nanoporous gold film etched by hydrochloric acid is uniform with a cover of fog-like moieties.

  4. [Biosynthesis of gold nanoparticles by Azospirillum brasilense].

    Science.gov (United States)

    Kupriashina, M A; Vetchinkina, E P; Burov, A M; Ponomareva, E G; Nikitina, V E

    2014-01-01

    Plant-associated nitrogen-fixing soil bacteria Azospirillum brasilense were shown to reduce the gold of chloroauric acid to elemental gold, resulting in formation of gold nanoparicles. Extracellular phenoloxidizing enzymes (laccases and Mn peroxidases) were shown to participate in reduction of Au+3 (HAuCl4) to Au(0). Transmission electron microscopy revealed accumulation of colloidal gold nanoparticles of diverse shape in the culture liquid of A. brasilense strains Sp245 and Sp7. The size of the electron-dense nanospheres was 5 to 50 nm, and the size of nanoprisms varied from 5 to 300 nm. The tentative mechanism responsible for formation of gold nanoparticles is discussed.

  5. Relativistic effects in homogeneous gold catalysis.

    Science.gov (United States)

    Gorin, David J; Toste, F Dean

    2007-03-22

    Transition-metal catalysts containing gold present new opportunities for chemical synthesis, and it is therefore not surprising that these complexes are beginning to capture the attention of the chemical community. Cationic phosphine-gold(i) complexes are especially versatile and selective catalysts for a growing number of synthetic transformations. The reactivity of these species can be understood in the context of theoretical studies on gold; relativistic effects are especially helpful in rationalizing the reaction manifolds available to gold catalysts. This Review draws on experimental and computational data to present our current understanding of homogeneous gold catalysis, focusing on previously unexplored reactivity and its application to the development of new methodology.

  6. Mammalian sensitivity to elemental gold (Au?)

    Science.gov (United States)

    Eisler, R.

    2004-01-01

    There is increasing documentation of allergic contact dermatitis and other effects from gold jewelry, gold dental restorations, and gold implants. These effects were especially pronounced among females wearing body-piercing gold objects. One estimate of the prevalence of gold allergy worldwide is 13%, as judged by patch tests with monovalent organogold salts. Eczema of the head and neck was the most common response of individuals hypersensitive to gold, and sensitivity can last for at least several years. Ingestion of beverages containing flake gold can result in allergic-type reactions similar to those seen in gold-allergic individuals exposed to gold through dermal contact and other routes. Studies with small laboratory mammals and injected doses of colloidal gold showed increased body temperatures, accumulations in reticular cells, and dose enhancement in tumor therapy; gold implants were associated with tissue injuries. It is proposed that Au? toxicity to mammals is associated, in part, with formation of the more reactive Au+ and Au3+ species.

  7. Leaching behavior of butanedionedioxime as gold ligand

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Butanedionedioxime, a small organic compound with low-toxicity and good chemical stability, has been proposed as an effective gold ligand in gold extraction. The result of experiment shows that: 1) highly effective gold lixiviantcan be composed of butanedionedioxime (BDM) with many oxidants, especially potassium permanganate; 2)in the leaching system of BD M- K M nO4 the suitable Ox/Lig(ratio of oxidants to gold ligands) tange is 0.20 ~ 0. 50, optimally 0.25 ~0.45 at the pH range of 7 ~ 11; 3) BDM-KMnO4 extraction of gold from an oxide ore is similar to cyanide(cyanide-O2)extraction, but the leaching rate of gold by BDM-KMnO4 is faster than that by cyanide-O2; 4) gold may readily be recov-ered by carbon adsorption and zinc precipitation

  8. [Contact allergy to gold and its alloys. Pertinence of gold salt patch tests].

    Science.gov (United States)

    Collet, E; Lacroix, M; Dalac, S; Ponnelle, C; Lambert, D

    1994-01-01

    Allergic contact dermatitis to gold and its alloys is a rare affection and it is difficult to interpret gold salts patch tests. We report two cases of patients with positive patch tests to 0.5% sodium aurothiosulfate discovered during a dermatology exploration of an occupational contact eczema (for the first patient) and an intolerance to gold jewelry (for the second). There is much confusion in the literature concerning the allergologic exploration of contact dermatitis to gold: no standardized test, possible cross reactions between different gold salts, the tests often irritate. The mechanism of sensitization to gold salts is unknown since pure gold is inalterable and does not contain any salts. The pertinence of a positive test to one or more gold salts must therefore be examined carefully and the diagnosis of gold allergy must not be made without sufficient evidence.

  9. Enhanced photo-catalytic activity of gold ion and gold modified

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The gold ion modified TiO2 was prepared by means of sol- gelwhereas gold deposited TiO2 was prepared by means of photo- reduction. The physical properties were influenced significantly by the presence of gold ion or gold. The enhanced photo-activity of gold modified TiO2 was quantified in terms of methylene blue degradation. The presence of gold ion in TiO2 lattices or gold on TiO2 surface enhanced their photo-activity. The optimum molar content of gold ion doping and gold deposition all was 0.5%. The first-order rates constants of gold modified TiO2 was more than that of pure TiO2, and decreased by increasing the content of gold ion and gold when their contents were more than 0.5%. Gold iondoped in TiO2 lattices was more effective to enhance the photo-activity than gold on TiO2 surface. Moreover, the relationship between physical properties, chemical properties and photo-activityhas been discussed.

  10. Gold concentration in blood in relation to the number of gold restorations and contact allergy to gold.

    Science.gov (United States)

    Ahnlide, Ingela; Ahlgren, Camilla; Björkner, Bert; Bruze, Magnus; Lundh, Thomas; Möller, Halvor; Nilner, Krister; Schütz, Andrejs

    2002-10-01

    Previous studies have demonstrated an association between gold allergy and the presence of dental gold restorations. The aim of the present study was to investigate the relationship between the concentration of gold in blood (B-Au) and the number of tooth surfaces with gold alloys in subjects with and without contact allergy to gold. In 80 patients referred for patch testing because of eczematous disease, blood samples were taken and analyzed for B-Au using inductively coupled plasma mass spectrometry. The detection limit for the Au determination was 0.04 microg/L. In addition, a dentist made a clinical and radiological examination of the patients and registered the number of dental gold surfaces. Patients with dental gold restorations had a statistically significantly higher B-Au in Mann-Whitney U test (P = 0.025), (range < 0.04-1.07 microg/L) than patients without (range < 0.04-0.15 microg/L). Furthermore, a positive correlation was found between B-Au and the number of dental gold surfaces (P < 0.01). There was no statistically significant difference in B-Au between persons with and without contact allergy to gold. The study thus indicates that gold is released from dental restorations and taken tip into the circulation.

  11. CMS Industries awarded gold, crystal

    CERN Multimedia

    2006-01-01

    The CMS collaboration honoured 10 of its top suppliers in the seventh annual awards ceremony The representatives of the firms that recieved the CMS Gold and Crystal Awards stand with their awards after the ceremony. The seventh annual CMS Awards ceremony was held on Monday 13 March to recognize the industries that have made substantial contributions to the construction of the collaboration's detector. Nine international firms received Gold Awards, and General Tecnica of Italy received the prestigious Crystal Award. Representatives from the companies attended the ceremony during the plenary session of CMS week. 'The role of CERN, its machines and experiments, beyond particle physics is to push the development of equipment technologies related to high-energy physics,'said CMS Awards Coordinator Domenico Campi. 'All of these industries must go beyond the technologies that are currently available.' Without the involvement of good companies over the years, the construction of the CMS detector wouldn't be possible...

  12. Nanobubble trouble on gold surfaces

    DEFF Research Database (Denmark)

    Holmberg, Maria; Kuhle, A.; Garnaes, J.

    2003-01-01

    When analyzing surfaces related to biosensors with in situ atomic force microscopy (AFM), the existence of nanobubbles called for our attention. The bubbles seem to form spontaneously when gold surfaces are immersed in clean water and are probably a general phenomenon at water-solid interfaces....... Besides from giving rise to undesired effects in, for example, biosensors, nanobubbles can also cause artifacts in AFM imaging. We have observed nanobubbles on unmodified gold surfaces, immersed in clean water, using standard silicon AFM probes. Nanobubbles can be made to disappear from contact mode AFM...... tip and the nanobubble indicates that a small tip cone angle and a relatively hydrophilic tip surface makes it possible to image nanobubbles with contact mode AFM even though the tip has penetrated the surface of the bubble....

  13. Switchable Imbibition in Nanoporous Gold

    CERN Document Server

    Xue, Yahui; Duan, Huiling; Weissmueller, Joerg; Huber, Patrick

    2014-01-01

    Spontaneous imbibition enables the elegant propelling of nano-flows because of the dominance of capillarity at small length scales. The imbibition kinetics are, however, solely determined by the static geometry of the porous host, the capillarity, and the fluidity of the imbibed liquid. This makes active control particularly challenging. Here, we show for aqueous electrolyte imbibition in nanoporous gold that the fluid flow can be reversibly switched on and off through electric potential control of the solid-liquid interfacial tension, i.e. we can accelerate the imbibition front, stop it, and have it proceed at will. Simultaneous measurements of the mass flux and the electrical current allow us to document simple scaling laws for the imbibition kinetics, and to explore the charge flow dynamics in the metallic nanopores. Our findings demonstrate that the high electric conductivity along with the pathways for ionic and/or fluid transport render nanoporous elemental gold a versatile, accurately controllable elec...

  14. Biomolecular Assembly of Gold Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Micheel, Christine Marya [Univ. of California, Berkeley, CA (United States)

    2005-05-20

    Over the past ten years, methods have been developed to construct discrete nanostructures using nanocrystals and biomolecules. While these frequently consist of gold nanocrystals and DNA, semiconductor nanocrystals as well as antibodies and enzymes have also been used. One example of discrete nanostructures is dimers of gold nanocrystals linked together with complementary DNA. This type of nanostructure is also known as a nanocrystal molecule. Discrete nanostructures of this kind have a number of potential applications, from highly parallel self-assembly of electronics components and rapid read-out of DNA computations to biological imaging and a variety of bioassays. My research focused in three main areas. The first area, the refinement of electrophoresis as a purification and characterization method, included application of agarose gel electrophoresis to the purification of discrete gold nanocrystal/DNA conjugates and nanocrystal molecules, as well as development of a more detailed understanding of the hydrodynamic behavior of these materials in gels. The second area, the development of methods for quantitative analysis of transmission electron microscope data, used computer programs written to find pair correlations as well as higher order correlations. With these programs, it is possible to reliably locate and measure nanocrystal molecules in TEM images. The final area of research explored the use of DNA ligase in the formation of nanocrystal molecules. Synthesis of dimers of gold particles linked with a single strand of DNA possible through the use of DNA ligase opens the possibility for amplification of nanostructures in a manner similar to polymerase chain reaction. These three areas are discussed in the context of the work in the Alivisatos group, as well as the field as a whole.

  15. Gemballa Mirage GT Gold Edition

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    前不久,保时捷的专业改装厂Gembaila推出了一款Mirage GT Gold Edition,这款车以Carrera GT为基础,并且使用了大量的碳纤维材料,而且在车身内外配备了一些黄金色的涂装。

  16. CO extrusion in homogeneous gold catalysis: reactivity of gold acyl species generated through water addition to gold vinylidenes.

    Science.gov (United States)

    Bucher, Janina; Stößer, Tim; Rudolph, Matthias; Rominger, Frank; Hashmi, A Stephen K

    2015-01-26

    Herein, we describe a new gold-catalyzed decarbonylative indene synthesis. Synergistic σ,π-activation of diyne substrates leads to gold vinylidene intermediates, which upon addition of water are transformed into gold acyl species, a type of organogold compound hitherto only scarcely reported. The latter are shown to undergo extrusion of CO, an elementary step completely unknown for homogeneous gold catalysis. By tuning the electronic and steric properties of the starting diyne systems, this new reactivity could be exploited for the synthesis of indene derivatives in high yields.

  17. Feasibilty of electroplated gold for hybrid microcircuits

    Energy Technology Data Exchange (ETDEWEB)

    Blessner, P.L.

    1978-01-01

    Electroplating was investigated as a method of providing thick gold films. Because electroplated gold has never been used for hybrid microcircuit (HMC) substrate metallization, this feasibility study was also designed to determine the characteristics of electroplated gold and its compatibility with present HMC fabrication processes. Ceramic substrates 95 by 114 mm (3.75 by 4.5 in.) were electroplated with 6, 10, and 25 ..mu..m of gold after 0.02 ..mu..m of chromium and 0.5 ..mu..m of gold had been either sputtered or vacuum evaporated onto the substrate surfaces. Substrates vacuum evaporated with 6 ..mu..m of gold were used as a control group. The substrates were evaluated for via resistance, RF electrical characteristics, conductor definition and resolution, solder wettability, thermocompression bondability, and environmental stability.

  18. Linear Optical Properties of Gold Colloid

    Directory of Open Access Journals (Sweden)

    Jingmin XIA

    2015-11-01

    Full Text Available Gold colloid was prepared by reducing HAuCl4·4H2O with Na3C6H5O7·2H2O. The morphology, size of gold nanoparticles and the optical property of colloid were characterized by transmission electron microscope and UV-Vis spectrophotometer, respectively. It shows that the gold nanoparticles are in the shape of spheres with diameters less than 8 nm, and the surface plasmon resonance absorption peak is located at about 438 nm. As the volume fraction of gold particles increases, the intensity of absorption peak strengthens. The optical property of gold colloid was analyzed by Maxwell-Garnett (MG effective medium theory in the company of Drude dispersion model. The results show that the matrix dielectric constant is a main factor, which influences the optical property of gold colloid.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9558

  19. Nonlinear seismic response analysis of reinforced concrete tube in tube structure

    Institute of Scientific and Technical Information of China (English)

    WANG Hai-bo; SHEN Pu-sheng

    2005-01-01

    Super-highly reinforced concrete tube in tube structure is a developing structure system of high-rise building. The more reasonable derivation process of the multi-vertical-line-element model stiffness matrix is given.On the premise of pointing out the problems of present multi-spring element model, combined with present multivertical-line-element model for analyzing on shear wall, the model is expanded to spatial one, and the stiffness matrix of which is derived. Combined with hysteretic axial model and hysteretic shear model, it is suitable for columns,wall limbs and beams with all kinds of section form. Some examples are calculated and compared with test results,which shows that the models have relatively good accuracy. On the base of the experimental phenomenon and failure mechanism for tube in tube structure specimen, nonlinear seismic responses analysis program on the basis of the advantaged element model for tube in tube structure is developed. Calculation results are in good agreement with those of the pseudo-dynamic tests and the failure mechanism can be well reflected.

  20. Electrochemical Assay of Gold-Plating Solutions

    Science.gov (United States)

    Chiodo, R.

    1982-01-01

    Gold content of plating solution is assayed by simple method that required only ordinary electrochemical laboratory equipment and materials. Technique involves electrodeposition of gold from solution onto electrode, the weight gain of which is measured. Suitable fast assay methods are economically and practically necessary in electronics and decorative-plating industries. If gold content in plating bath is too low, poor plating may result, with consequent economic loss to user.

  1. The Gold Standard Since Alec Ford

    OpenAIRE

    Eichengreen, Barry

    1989-01-01

    This paper surveys studies of the operation of the classical gold standard published subsequent to the appearance of Alec Ford's The Gold Standard 1880-1914: Britain and Argentina in 1962. Contributions tend to fall under two headings: those which emphasize stock equilibrium in money markets (examples of the so-called "monetary approach") and those which emphasize instead stockflow interactions in bond markets. The paper then addresses the perennial question of how the gold standard worked. A...

  2. Gold and Silver Extraction from Leach Solutions

    Directory of Open Access Journals (Sweden)

    Bagdaulet K. Kenzhaliyev

    2014-03-01

    Full Text Available There has been carried out an investigation on the extraction of gold and silver from thiosulfate solutions: standard test and technological solutions of chemical and electrochemical leaching. The influence of related metals on the process of extracting gold from solution was studied. There has been conducted a comparative study of the IR spectra of solutions after the sorption of gold, silver and related metals.

  3. Gold Photoluminescence: Wavelength and Polarization Engineering

    DEFF Research Database (Denmark)

    Andersen, Sebastian Kim Hjælm; Pors, Anders Lambertus; Bozhevolnyi, Sergey I.

    2015-01-01

    We demonstrate engineering of the spectral content and polarization of photoluminescence (PL) from arrayed gold nanoparticles atop a subwavelength-thin dielectric spacer and optically-thick gold film, a configuration that supports gap-surface plasmon resonances (GSPRs). Choice of shapes and dimen......We demonstrate engineering of the spectral content and polarization of photoluminescence (PL) from arrayed gold nanoparticles atop a subwavelength-thin dielectric spacer and optically-thick gold film, a configuration that supports gap-surface plasmon resonances (GSPRs). Choice of shapes...

  4. Gold Rushes and mineral property rights allocation

    DEFF Research Database (Denmark)

    Sinding, Knud

    , is to handle the other projects that are generated by the "gold rush" informational externalities created by the initial discovery. At the core of the problems of dealing with a gold rush situation is both the informational externality and an institutional framework which is not designed to deal with large...... influxes of prospectors competing for a very limited area. This paper charts significant gold rush events in the mineral industry in recent decades and uses preliminary data on the areas impacted by these gold rushes to argue that many mineral tenure systems should be modified in order to be better able...

  5. CO oxidation on gold nanoparticles: Theoretical studies

    DEFF Research Database (Denmark)

    Remediakis, Ioannis; Lopez, Nuria; Nørskov, Jens Kehlet

    2005-01-01

    We present a summary of our theoretical results regarding CO oxidation on both oxide-supported and isolated gold nanoparticles. Using Density Functional Theory we have studied the adsorption of molecules and the oxidation reaction of CO on gold clusters. Low-coordinated sites on the gold...... nanoparticles can adsorb small inorganic molecules such as O2 and CO, and the presence of these sites is the key factor for the catalytic properties of supported gold nanoclusters. Other contributions, induced by the presence of the support, can provide parallel channels for the reaction and modulate the final...

  6. The Stabilizing Effects in Gold Carbene Complexes.

    Science.gov (United States)

    Nunes Dos Santos Comprido, Laura; Klein, Johannes E M N; Knizia, Gerald; Kästner, Johannes; Hashmi, A Stephen K

    2015-08-24

    Bonding and stabilizing effects in gold carbene complexes are investigated by using Kohn-Sham density functional theory (DFT) and the intrinsic bond orbital (IBO) approach. The π-stabilizing effects of organic substituents at the carbene carbon atom coordinated to the gold atom are evaluated for a series of recently isolated and characterized complexes, as well as intermediates of prototypical 1,6-enyne cyclization reactions. The results indicate that these effects are of particular importance for gold complexes especially because of the low π-backbonding contribution from the gold atom. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Gold Nanoparticle Mediated Phototherapy for Cancer

    Directory of Open Access Journals (Sweden)

    Cuiping Yao

    2016-01-01

    Full Text Available Gold nanoparticles exhibit very unique physiochemical and optical properties, which now are extensively studied in range of medical diagnostic and therapeutic applications. In particular, gold nanoparticles show promise in the advancement of cancer treatments. This review will provide insights into the four different cancer treatments such as photothermal therapy, gold nanoparticle-aided photodynamic therapy, gold nanoparticle-aided radiation therapy, and their use as drug carrier. We also discuss the mechanism of every method and the adverse effects and its limitations.

  8. [Intracellular gold content of circulating blood cells using various gold compounds].

    Science.gov (United States)

    Herrlinger, J D; Beress, R; Hecker, U

    1984-01-01

    Evidence on the action mechanisms of gold salts in the treatment of rheumatoid arthritis is still inconclusive. The intracellular localization of the place of action is likely. Therefore not only the serum gold levels but also the intracellular concentration of gold are of special interest. We measured the gold concentration in the serum and in the blood cells after in vitro application of aurothiomalate (Tauredon), gold keratinate (Auro-Detoxin) and triethylphosphine-gold (Ridaura) and in blood samples of patients undergoing these gold salts treatments. Cell-bound concentrations were found to vary extensively as a function of the gold compound used. While no or very little gold was present intracellularly after administration of the 2 parenteral drugs, up to 40% of the circulating gold was found to bind to the cells after administration of the triethylphosphine compound for gastro-intestinal absorption. The red cell concentration was more or less the same as that in the extracellular compartment. Gold apparently accumulated in the white cells, because the cell-bound concentration relative to unit volume was up to 20 times higher than the plasma level. The method used did not offer any information on the actual binding site of gold in white cells, i.e. cytoplasm versus nucleus versus cell membrane.

  9. Gold Fever! Seattle Outfits the Klondike Gold Rush. Teaching with Historic Places.

    Science.gov (United States)

    Blackburn, Marc K.

    This lesson is based on the National Register of Historic Places registration file, "Pioneer Square Historic District," and other sources about Seattle (Washington) and the Klondike Gold Rush. The lesson helps students understand how Seattle exemplified the prosperity of the Klondike Gold Rush after 1897 when news of a gold strike in…

  10. Ultrafast vibrations of gold nanorings

    DEFF Research Database (Denmark)

    Kelf, T; Tanaka, Y; Matsuda, O;

    2011-01-01

    elucidate the corresponding mode shapes and find that the substrate plays an important role in determining the mode damping. This study demonstrates the need for a plasmonic nano-optics approach to understand the optical excitation and detection mechanisms for the vibrations of plasmonic nanostructures.......We investigate the vibrational modes of gold nanorings on a silica substrate with an ultrafast optical technique. By comparison with numerical simulations, we identify several resonances in the gigahertz range associated with axially symmetric deformations of the nanoring and substrate. We...

  11. Sorption Recovery of Gold Thiosulphate Complexes

    Institute of Scientific and Technical Information of China (English)

    A.G.Kholmogorov; O.N.Kononova; 等

    2002-01-01

    The gold sorption from thiosulphate solutions on carbon sorbents and on anion exchangers was studied. It was shown that the anion exchangers AV-17-10P and AP-100 are the most effective and selective at pH=5-8. These anion exchangers can be recommended for the gold recovery from the industrial solutions.

  12. 2008: Golden Time in Gold Market

    Institute of Scientific and Technical Information of China (English)

    Guo; Yan

    2008-01-01

      Pushed by increased demand from both jewelers and investors, China has become the drivin, g force behind the world's gold market in 2007. Chinas gold market this year has maintained its growing momentum with booming demand, not only in the domestic market but also in the international market.……

  13. 2008: Golden Time in Gold Market

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Pushed by increased demand from both jewelers and investors, China has become the drivin, g force behind the world's gold market in 2007. Chinas gold market this year has maintained its growing momentum with booming demand, not only in the domestic market but also in the international market.

  14. Gold-Collar Workers. ERIC Digest.

    Science.gov (United States)

    Wonacott, Michael E.

    The gold-collar worker has problem-solving abilities, creativity, talent, and intelligence; performs non-repetitive and complex work difficult to evaluate; and prefers self management. Gold-collar information technology workers learn continually from experience; recognize the synergy of teams; can demonstrate leadership; and are strategic thinkers…

  15. Galvanic Synthesis of Hollow Gold Nanoshells

    Science.gov (United States)

    2015-02-01

    pulses in the NIR.2 The advantage of hollow nanoshells over solid gold (Au) or silver (Ag) nanoparticles , or alloys thereof,3 is that the...Karna SP. Synthesis of gold and silver nanoparticles and characterization of structural, optical, and electronic properties. Aberdeen Proving Ground...

  16. Goudafzettingen in Suriname (Gold deposits in Surinam)

    NARCIS (Netherlands)

    Brinck, J.W.

    1956-01-01

    THE GOLD DEPOSITS IN SURINAM AND THE DISTRIBUTION OF CONCESSIONS THROUGH THE COUNTRY The fieldwork on the occurrence of primary and secondary gold deposits in Surinam on which this thesis is based was carried out by order of the Welfare Fund Surinam (Welvaarts Fonds Suriname) during the periods

  17. Nonlinear optical studies of single gold nanoparticles

    NARCIS (Netherlands)

    Dijk, Meindert Alexander van

    2007-01-01

    Gold nanoparticles are spherical clusters of gold atoms, with diameters typically between 1 and 100 nanometers. The applications of these particles are rather diverse, from optical labels for biological experiments to data carrier for optical data storage. The goal of my project was to develop new

  18. Numerical simulations of nanostructured gold films

    DEFF Research Database (Denmark)

    Repän, Taavi; Frydendahl, Christian; Novikov, Sergey M.

    2017-01-01

    We present an approach to analyse near-field effects on nanostructured gold films by finite element simulations. The studied samples are formed by fabricating gold films near the percolation threshold and then applying laser damage. Resulting samples have complicated structures, which...

  19. Goudafzettingen in Suriname (Gold deposits in Surinam)

    NARCIS (Netherlands)

    Brinck, J.W.

    1956-01-01

    THE GOLD DEPOSITS IN SURINAM AND THE DISTRIBUTION OF CONCESSIONS THROUGH THE COUNTRY The fieldwork on the occurrence of primary and secondary gold deposits in Surinam on which this thesis is based was carried out by order of the Welfare Fund Surinam (Welvaarts Fonds Suriname) during the periods Dece

  20. Goudafzettingen in Suriname (Gold deposits in Surinam)

    NARCIS (Netherlands)

    Brinck, J.W.

    1956-01-01

    THE GOLD DEPOSITS IN SURINAM AND THE DISTRIBUTION OF CONCESSIONS THROUGH THE COUNTRY The fieldwork on the occurrence of primary and secondary gold deposits in Surinam on which this thesis is based was carried out by order of the Welfare Fund Surinam (Welvaarts Fonds Suriname) during the periods Dece

  1. RF Sputtering of Gold Contacts On Niobium

    Science.gov (United States)

    Barr, D. W.

    1983-01-01

    Reliable gold contacts are deposited on niobium by combination of RF sputtering and photolithography. Process results in structures having gold only where desired for electrical contact. Contacts are stable under repeated cycling from room temperature to 4.2 K and show room-temperature contact resistance as much as 40 percent below indium contacts made by thermalcompression bonding.

  2. Sesquicentennial: Gold Rush to Golden Statehood.

    Science.gov (United States)

    Sabato, George

    1998-01-01

    Provides an annotated bibliography of educational resources that can be used to support instructional units on the Gold Rush or the sesquicentennial of California's statehood. The materials include workbooks, videos, teacher's guides, monographs, and magazines. Offers a brief history of the Gold Rush and a set of relevant discussion questions.…

  3. Computational approaches to homogeneous gold catalysis.

    Science.gov (United States)

    Faza, Olalla Nieto; López, Carlos Silva

    2015-01-01

    Homogenous gold catalysis has been exploding for the last decade at an outstanding pace. The best described reactivity of Au(I) and Au(III) species is based on gold's properties as a soft Lewis acid, but new reactivity patterns have recently emerged which further expand the range of transformations achievable using gold catalysis, with examples of dual gold activation, hydrogenation reactions, or Au(I)/Au(III) catalytic cycles.In this scenario, to develop fully all these new possibilities, the use of computational tools to understand at an atomistic level of detail the complete role of gold as a catalyst is unavoidable. In this work we aim to provide a comprehensive review of the available benchmark works on methodological options to study homogenous gold catalysis in the hope that this effort can help guide the choice of method in future mechanistic studies involving gold complexes. This is relevant because a representative number of current mechanistic studies still use methods which have been reported as inappropriate and dangerously inaccurate for this chemistry.Together with this, we describe a number of recent mechanistic studies where computational chemistry has provided relevant insights into non-conventional reaction paths, unexpected selectivities or novel reactivity, which illustrate the complexity behind gold-mediated organic chemistry.

  4. Preparation of conductive gold nanowires in confined environment of gold-filled polymer nanotubes.

    Science.gov (United States)

    Mitschang, Fabian; Langner, Markus; Vieker, Henning; Beyer, André; Greiner, Andreas

    2015-02-01

    Continuous conductive gold nanofibers are prepared via the "tubes by fiber templates" process. First, poly(l-lactide) (PLLA)-stabilized gold nanoparticles (AuNP) with over 60 wt% gold are synthesized and characterized, including gel permeation chromatography coupled with a diode array detector. Subsequent electrospinning of these AuNP with template PLLA results in composite nanofibers featuring a high gold content of 57 wt%. Highly homogeneous gold nanowires are obtained after chemical vapor deposition of 345 nm of poly(p-xylylene) (PPX) onto the composite fibers followed by pyrolysis of the polymers at 1050 °C. The corresponding heat-induced transition from continuous gold-loaded polymer tubes to smooth gold nanofibers is studied by transmission electron microscopy and helium ion microscopy using both secondary electrons and Rutherford backscattered ions.

  5. Gold Liquid Crystals in the XXI Century

    Directory of Open Access Journals (Sweden)

    Manuel Bardají

    2014-08-01

    Full Text Available Since the first gold liquid crystal was described in 1986, much effort has been done to prepare new compounds bearing this property. The review deals with the last results obtained in this new century. Gold(I has a strong affinity to give linear co-ordination and metal-metal interactions, which produce a rich supramolecular chemistry, and can promote the behavior as liquid crystal. Therefore, most liquid crystals are based on rod-like gold(I compounds, while gold(III liquid crystals are scarce. Calamitic and discotic mesogens have been reported, as well as chiral liquid crystals. Weak interactions such as H-bonds have also been used to obtain gold mesogens. Some of them exhibit additional properties, such as color, luminescence, and chirality. Luminescence has been reported, not only in the solid state or in solution, but also in the mesophase. This is relevant for applications in LEDs (Light Emitting Diodes, information storage, and sensors.

  6. Magnetically mediated vortexlike assembly of gold nanoshells.

    Science.gov (United States)

    Sun, Jianfei; Dong, Jian; Sun, Dongke; Guo, Zhirui; Gu, Ning

    2012-04-24

    Gold nanoshells currently attract increasing research interests due to the important role in many subjects. For practical applications, random arrangement of the nanoparticles is often unfavored so that the assembly of gold nanoshells is becoming a central issue. We here proposed to utilize time-variant magnetic field to direct the assembly of gold nanoshells. It was discovered that the alternating magnetic field can mediate the vortex-like assembly of gold nanoshells. The mechanism was explored and thought to be relative with the electric field of induction which caused the thermal gradient on the substrate and the electric force. The vortexlike structure as well as the assembly mechanism will play an important role in research and application of gold nanomaterials.

  7. Tailored nanoporous gold for ultrahigh fluorescence enhancement.

    Science.gov (United States)

    Lang, X Y; Guan, P F; Fujita, T; Chen, M W

    2011-03-07

    We report molecular fluorescence enhancement of free-standing nanoporous gold in which the nanoporosity can be arbitrarily tailored by the combination of dealloying and electroless gold plating. The nanoporous gold fabricated by this facile method possesses unique porous structures with large gold ligaments and very small pores, and exhibits significant improvements in surface enhanced fluorescence as well as structure rigidity. It demonstrates that the confluence effect of improved quantum yield and excitation of fluorophores is responsible for the large fluorescence enhancement due to the near-field enhancement of nanoporous gold, which arises from the strong electromagnetic coupling between neighboring ligaments and the weakening of plasmon damping of the large ligaments because of the small pore size and large ligament size, respectively.

  8. Ordering Gold Nanoparticles with DNA Origami Nanoflowers.

    Science.gov (United States)

    Schreiber, Robert; Santiago, Ibon; Ardavan, Arzhang; Turberfield, Andrew J

    2016-08-23

    Nanostructured materials, including plasmonic metamaterials made from gold and silver nanoparticles, provide access to new materials properties. The assembly of nanoparticles into extended arrays can be controlled through surface functionalization and the use of increasingly sophisticated linkers. We present a versatile way to control the bonding symmetry of gold nanoparticles by wrapping them in flower-shaped DNA origami structures. These "nanoflowers" assemble into two-dimensonal gold nanoparticle lattices with symmetries that can be controlled through auxiliary DNA linker strands. Nanoflower lattices are true composites: interactions between the gold nanoparticles are mediated entirely by DNA, and the DNA origami will fold into its designed form only in the presence of the gold nanoparticles.

  9. Molecular Beam Optical Study of Gold Sulfide and Gold Oxide

    Science.gov (United States)

    Zhang, Ruohan; Yu, Yuanqin; Steimle, Timothy

    2016-06-01

    Gold-sulfur and gold-oxygen bonds are key components to numerous established and emerging technologies that have applications as far ranging as medical imaging, catalysis, electronics, and material science. A major theoretical challenge for describing this bonding is correctly accounting for the large relativistic and electron correlation effects. Such effects are best studied in diatomic, AuX, molecules. Recently, the observed AuS electronic state energy ordering was measured and compared to a simple molecular orbital diagram prediction. Here we more thoroughly investigate the nature of the electronic states of both AuS and AuO from the analysis of high-resolution (FWHM\\cong35MHz) optical Zeeman spectroscopy of the (0,0){B}2Σ--{X}2Π3/2 bands. The determined fine and hyperfine parameters for the {B}2Σ- state of AuO differ from those extracted from the analysis of a hot, Doppler-limited, spectrum. It is demonstrated that the nature of the {B}2Σ- states of AuO and AuS are radically different. The magnetic tuning of AuO and AuS indicates that the {B}2Σ- states are heavily contaminated. Supported by the National Science Foundation under Grant No.1265885. D. L. Kokkin, R. Zhang, T. C. Steimle, I. A. Wyse, B. W. Pearlman and T. D. Varberg, J. Phys. Chem. A., 119(48), 4412, 2015. L. C. O'Brien, B. A. Borchert, A. Farquhar, S. Shaji, J. J. O'Brien and R. W. Field, J. Mol. Spectrosc., 252(2), 136, 2008

  10. Pressure losses during steam flow and condensation in tubes and channels

    Science.gov (United States)

    Leontiev, A. I.; Milman, O. O.

    2014-12-01

    Theoretical and experimental investigations have revealed the dependence of parameters of the process of steam condensation in tubes and channels on the scheme of heat-exchange fluid flow, including counter, forward, and cross flow systems. The total pressure losses in the case of counter flow are greater than those in the case of forward and cross flow. This dependence is valid for the flow of gases and plasma in channels with significant density variation (e.g., due to heating and cooling). Pressure losses have been evaluated using various computational models, and the results are compared to experimental data.

  11. Agreement between QuantiFERON(R)-TB Gold In-Tube and the tuberculin skin test and predictors of positive test results in Warao Amerindian pediatric tuberculosis contacts

    NARCIS (Netherlands)

    Verhagen, L.M.; Maes, M.; Villalba, J.A.; d'Alessandro, A.; Rodriguez, L.P.; Espana, M.F.; Hermans, P.W.M.; Waard, J.H. de

    2014-01-01

    BACKGROUND: Interferon-gamma release assays have emerged as a more specific alternative to the tuberculin skin test (TST) for detection of tuberculosis (TB) infection, especially in Bacille Calmette-Guerin (BCG) vaccinated people. We determined the prevalence of Mycobacterium tuberculosis infection

  12. Fluctuating Behavior and Influential Factors in the Performance of the QuantiFERON-TB Gold In-Tube Assay in the Diagnosis of Tuberculosis: e0103763

    National Research Council Canada - National Science Library

    Lei Bao; Tao Li; Ni Diao; Yaojie Shen; Lingyun Shao; Ying Zhang; Shuihua Lu; Wenhong Zhang

    2015-01-01

    ...] release assay for diagnosing tuberculosis (TB). However, research has not determined whether age or the use of an immune suppressive or anti-TB treatment influences this assay's ability to detect TB...

  13. Fluctuating Behavior and Influential Factors in the Performance of the QuantiFERON-TB Gold In-Tube Assay in the Diagnosis of Tuberculosis

    National Research Council Canada - National Science Library

    Bao, Lei; Li, Tao; Diao, Ni; Shen, Yaojie; Shao, Lingyun; Zhang, Ying; Lu, Shuihua; Zhang, Wenhong

    2015-01-01

    ... release assay for diagnosing tuberculosis (TB). However, research has not determined whether age or the use of an immune suppressive or anti-TB treatment influences this assay's ability to detect TB...

  14. Comparison of the 2-step tuberculin skin test and QuantiFERON-TB Gold in-Tube test in the screening of latent tuberculosis infection in cancer patients

    Directory of Open Access Journals (Sweden)

    Hala A. Mohammad

    2015-07-01

    Hematological malignancy group (HMgroup had significantly more positive TSTII results followed by the breast cancer group (p = 0.01. Similarly, QFT-GIT positive values were significantly more frequent in the HM group. This study suggests that the QFT-GIT test maintains its sensitivity and performance in immunocompromised cancer patients, identifying a large number of truly infected patients being anergy to the tuberculin skin test.

  15. The 'price' of Olympic Gold.

    Science.gov (United States)

    Hogan, K; Norton, K

    2000-06-01

    In 1981 the Commonwealth Government established the Australian Institute of Sport (AIS). The Australian Sports Commission (ASC) which administers the AIS has 2 objectives: (1) excellence in sports performances; and (2) increased participation in sports and sports activities. State-based institutes of sport have also been established with the same or very similar objectives. Federal policy directs the bulk of the ASC budget to elite athlete programs. A smaller proportion goes towards community participation. The official reason is based on the notion of the 'trickle-down' or 'demonstration' effect. That is, a flow-on of benefits to the broader community in the form of increased participation as a direct result of elite sports success. The aims of this study were to determine the (1) spending pattern to elite sports programs for the 5 Olympics 1976/77 to 1995/96, (2) evidence for the two ASC objectives having been met, and (3) expected medal tally at the 2000 Olympic Games. Results show funding (in 1998 dollars), has accelerated from about $1.2 million (1976/77) to $106 million in (1997/98), particularly since the Games were awarded to Sydney. The total amount spent on elite athletes was $0.918 billion. In the period 1980-96 Australia won 25 gold and 115 total Olympic medals. This equates to approximately $37 million per gold and $8 million per medal in general. There was a significant linear relationship between money spent and total medals won. This was also found when all medal types were analysed independently. The predicted medal tally in 2000 (based on the cost per medal and the expenditure towards Sydney) indicates the medal count will be about 14+/-1 gold, 15+/-2 silver and 33+/-4 bronze. Based on our nation's record of international sporting achievement, there is little doubt we have fulfilled the ASC's first objective. Current data on physical activity patterns of Australians suggest the second objective has not been met. Focusing attention on and achieving

  16. Cancer theranostics with gold nanoshells.

    Science.gov (United States)

    Zhao, Jun; Wallace, Michael; Melancon, Marites P

    2014-09-01

    Gold nanoshells (AuNSs) present a vivid example of integrating nanoscience in order to solve a biomedical problem. AuNSs exhibit tunable surface plasmon resonance, which can be tuned to the near-infrared region in order to realize optimal tissue penetration. The highly efficient light-to-heat transformation by AuNSs during laser irradiation causes thermal damage to the tumor without damaging healthy organs. Transient nanobubbles can form around AuNSs during laser treatment and induce mechanical stress specifically in tumor cells. AuNSs also serve as a versatile platform for the delivery of various diagnostic and therapeutic agents. In this article, we describe the physicochemical properties of AuNSs in the context of their design, preparation and application in cancer theranostics. Ultimately, we look beyond the current research on AuNSs and discussed future challenges to their successful translation into clinical use.

  17. Gold-catalyzed naphthalene functionalization

    Directory of Open Access Journals (Sweden)

    Iván Rivilla

    2011-05-01

    Full Text Available The complexes IPrMCl (IPr = 1,3-bis(diisopropylphenylimidazol-2-ylidene, M = Cu, 1a; M = Au, 1b, in the presence of one equiv of NaBAr'4 (Ar' = 3,5-bis(trifluoromethylphenyl, catalyze the transfer of carbene groups: C(RCO2Et (R = H, Me from N2C(RCO2Et to afford products that depend on the nature of the metal center. The copper-based catalyst yields exclusively a cycloheptatriene derivative from the Buchner reaction, whereas the gold analog affords a mixture of products derived either from the formal insertion of the carbene unit into the aromatic C–H bond or from its addition to a double bond. In addition, no byproducts derived from carbene coupling were observed.

  18. Gold film resistor bolometric array

    Energy Technology Data Exchange (ETDEWEB)

    Yin Fuxian [Academia Sinica, Hefei, AH (China). Inst. of Plasma Physics

    1997-03-01

    A new type of bolometric array diagnostic system has been developed for HT-6M tokamak and HT-7 superconductor tokamak plasma physics experimental research. This system is composed of temperature-sensitive detectors of gold film resistor and phase-sensitive rectifiers of the bridge excited by square waves. With this system, a radiation detection limit of 192.0 {mu}W cm{sup -2} at a spatial resolution of 2.0 cm and a temporal resolution of 1.0 mS. The system features a high temperature baking resistance, ultra high vacuum endurance, sufficient insensitivity to radiation damage, sufficient suppression of electromagnetic interference, good long-term stability, high radiation sensitivity and measurement data reliability. Absolute calibration of the detectors is performed simultaneously and in situ by means of a built-in electronic power pulse. (orig.) 9 refs.

  19. Origin of the transition voltage in gold-vacuum-gold atomic junctions.

    Science.gov (United States)

    Wu, Kunlin; Bai, Meilin; Sanvito, Stefano; Hou, Shimin

    2013-01-18

    The origin and the distance dependence of the transition voltage of gold-vacuum-gold junctions are investigated by employing first-principles quantum transport simulations. Our calculations show that atomic protrusions always exist on the electrode surface of gold-vacuum-gold junctions fabricated using the mechanically controllable break junction (MCBJ) method. The transition voltage of these gold-vacuum-gold junctions with atomically sharp electrodes is determined by the local density of states (LDOS) of the apex gold atom on the electrode surface rather than by the vacuum barrier shape. More specifically, the absolute value of the transition voltage roughly equals the rising edge of the LDOS peak contributed by the 6p atomic orbitals of the gold atoms protruding from the electrode surface, whose local Fermi level is shifted downwards when a bias voltage is applied. Since the LDOS of the apex gold atom depends strongly on the exact shape of the electrode, the transition voltage is sensitive to the variation of the atomic configuration of the junction. For asymmetric junctions, the transition voltage may also change significantly depending on the bias polarity. Considering that the occurrence of the transition voltage requires the electrode distance to be larger than a critical value, the interaction between the two electrodes is actually rather weak. Consequently, the LDOS of the apex gold atom is mainly determined by its local atomic configuration and the transition voltage only depends weakly on the electrode distance as observed in the MCBJ experiments.

  20. The giant Jiaodong gold province: The key to a unified model for orogenic gold deposits?

    Directory of Open Access Journals (Sweden)

    David I. Groves

    2016-05-01

    Full Text Available Although the term orogenic gold deposit has been widely accepted for all gold-only lode-gold deposits, with the exception of Carlin-type deposits and rare intrusion-related gold systems, there has been continuing debate on their genesis. Early syngenetic models and hydrothermal models dominated by meteoric fluids are now clearly unacceptable. Magmatic-hydrothermal models fail to explain the genesis of orogenic gold deposits because of the lack of consistent spatially – associated granitic intrusions and inconsistent temporal relationships. The most plausible, and widely accepted, models involve metamorphic fluids, but the source of these fluids is hotly debated. Sources within deeper segments of the supracrustal successions hosting the deposits, the underlying continental crust, and subducted oceanic lithosphere and its overlying sediment wedge all have their proponents. The orogenic gold deposits of the giant Jiaodong gold province of China, in the delaminated North China Craton, contain ca. 120 Ma gold deposits in Precambrian crust that was metamorphosed over 2000 million years prior to gold mineralization. The only realistic source of fluid and gold is a subducted oceanic slab with its overlying sulfide-rich sedimentary package, or the associated mantle wedge. This could be viewed as an exception to a general metamorphic model where orogenic gold has been derived during greenschist- to amphibolite-facies metamorphism of supracrustal rocks: basaltic rocks in the Precambrian and sedimentary rocks in the Phanerozoic. Alternatively, if a holistic view is taken, Jiaodong can be considered the key orogenic gold province for a unified model in which gold is derived from late-orogenic metamorphic devolatilization of stalled subduction slabs and oceanic sediments throughout Earth history. The latter model satisfies all geological, geochronological, isotopic and geochemical constraints but the precise mechanisms of auriferous fluid release, like many

  1. The giant Jiaodong gold province:The key to a unified model for orogenic gold deposits?

    Institute of Scientific and Technical Information of China (English)

    David I. Groves; M. Santosh

    2016-01-01

    Although the term orogenic gold deposit has been widely accepted for all gold-only lode-gold deposits, with the exception of Carlin-type deposits and rare intrusion-related gold systems, there has been continuing debate on their genesis. Early syngenetic models and hydrothermal models dominated by meteoric fluids are now clearly unacceptable. Magmatic-hydrothermal models fail to explain the genesis of orogenic gold deposits because of the lack of consistent spatially e associated granitic intrusions and inconsistent temporal relationships. The most plausible, and widely accepted, models involve meta-morphic fluids, but the source of these fluids is hotly debated. Sources within deeper segments of the supracrustal successions hosting the deposits, the underlying continental crust, and subducted oceanic lithosphere and its overlying sediment wedge all have their proponents. The orogenic gold deposits of the giant Jiaodong gold province of China, in the delaminated North China Craton, contain ca. 120 Ma gold deposits in Precambrian crust that was metamorphosed over 2000 million years prior to gold mineralization. The only realistic source of fluid and gold is a subducted oceanic slab with its overlying sulfide-rich sedimentary package, or the associated mantle wedge. This could be viewed as an exception to a general metamorphic model where orogenic gold has been derived during greenschist- to amphibolite-facies metamorphism of supracrustal rocks: basaltic rocks in the Precambrian and sedi-mentary rocks in the Phanerozoic. Alternatively, if a holistic view is taken, Jiaodong can be considered the key orogenic gold province for a unified model in which gold is derived from late-orogenic metamorphic devolatilization of stalled subduction slabs and oceanic sediments throughout Earth history. The latter model satisfies all geological, geochronological, isotopic and geochemical constraints but the precise mechanisms of auriferous fluid release, like many other subduction

  2. Magnetic Ordering in Gold Nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Agrachev, Mikhail; Antonello, Sabrina; Dainese, Tiziano; Ruzzi, Marco; Zoleo, Alfonso; Aprà, Edoardo; Govind, Niranjan; Fortunelli, Alessandro; Sementa, Luca; Maran, Flavio

    2017-06-12

    Several research groups have observed magnetism in monolayer-protected gold-cluster samples, but the results were often contradictory and thus a clear understanding of this phenomenon is still missing. We used Au25(SCH2CH2Ph)180, which is a paramagnetic cluster that can be prepared with atomic precision and whose structure is known precisely. Previous magnetometry studies only detected paramagnetism. We used samples representing a range of crystallographic orders and studied their magnetic behaviors by electron paramagnetic resonance (EPR). As a film, Au25(SCH2CH2Ph)180 displays paramagnetic behavior but, at low temperature, ferromagnetic interactions are detectable. One or few single crystals undergo physical reorientation with the applied field and display ferromagnetism, as detected through hysteresis experiments. A large collection of microcrystals is magnetic even at room temperature and shows distinct paramagnetic, superparamagnetic, and ferromagnetic behaviors. Simulation of the EPR spectra shows that both spin-orbit coupling and crystal distortion are important to determine the observed magnetic behaviors. DFT calculations carried out on single cluster and periodic models predict values of spin6orbit coupling and crystal6splitting effects in agreement with the EPR derived quantities. Magnetism in gold nanoclusters is thus demonstrated to be the outcome of a very delicate balance of factors. To obtain reproducible results, the samples must be (i) controlled for composition and thus be monodispersed with atomic precision, (ii) of known charge state, and (iii) well defined also in terms of crystallinity and experimental conditions. This study highlights the efficacy of EPR spectroscopy to provide a molecular understanding of these phenomena

  3. Alkanetelluroxide-protected gold nanoparticles.

    Science.gov (United States)

    Li, Ying; Silverton, Latoya C; Haasch, Richard; Tong, Yu Ye

    2008-07-15

    The synthesis and characterization of the first air-stable tellurium-containing ligand-protected gold nanoparticles (NPs) are reported. Although the synthesis largely followed the well-known Brust two-phase approach, the starting ligand was dioctyl ditelluride rather than alkanetellurol, which is an analogue of the widely used alkanethiol. Dioctyl ditelluride was used because alkanetellurol is unstable. The 1H and 13C NMR spectra, as well as infrared spectra (IR) of the formed Au NPs, indicated that the Te-Te bond in the starting ligand was broken but the octyl group was intact. This was further corroborated by the solid-state 125Te NMR spectrum that displayed a very broad and significantly downfield-shifted peak, indicating that tellurium was directly bound to the Au core. Furthermore, the O 1s and Te 3d XPS spectra of the Au NPs indicated that the capping ligands were octanetelluroxide. An average particle size of 2.7 nm diameter as measured by transmission electron microscopy (TEM) corresponded to an Au607 core. A two-step weight loss of approximately 22.2% in total was observed in the thermogravimetric analysis, which indicated about 53% ligand monolayer coverage (i.e., Au607(Te(=O)C8H17)133). Additionally, dioctyl ditelluride demonstrated an intriguing reductive power that led to a more sophisticated chemistry of forming the air-stable octanetelluroxide-protected gold NPs. It has been found that (1) when the ratio of Au to Te was about 1.5 a colorless intermediate state similar to Au(I)-SR (the intermediate state widely accepted in the synthesis of thiolate-protected Au NPs) could be obtained and (2) this kind of intermediate state played a key role in the formation of stable Au NPs.

  4. NUCLEATION STUDIES OF GOLD ON CARBON ELECTRODES

    Directory of Open Access Journals (Sweden)

    S. SOBRI

    2008-04-01

    Full Text Available Interest has grown in developing non-toxic electrolytes for gold electrodeposition to replace the conventional cyanide-based bath for long term sustainability of gold electroplating. A solution containing thiosulphate and sulphite has been developed specially for microelectronics applications. However, at the end of the electrodeposition process, the spent electrolyte can contain a significant amount of gold in solution. This study has been initiated to investigate the feasibility of gold recovery from a spent thiosulphate-sulphite electrolyte. We have used flat-plate glassy carbon and graphite electrodes to study the mechanism of nucleation and crystal growth of gold deposition from the spent electrolyte. It was found that at the early stages of reduction process, the deposition of gold on glassy carbon exhibits an instantaneous nucleation of non-overlapping particles. At longer times, the particles begin to overlap and the deposition follows a classic progressive nucleation phenomenon. On the other hand, deposition of gold on graphite does not follow the classical nucleation phenomena.

  5. Nature vs. nurture: gold perpetuates "stemness".

    Science.gov (United States)

    Paul, Willi; Sharma, Chandra P; Deb, Kaushik Dilip

    2011-01-01

    Adult tissues contain quiescent reservoirs of multipotent somatic stem cells and pluripotent embryonic-like stem cells (ELSCs). Credited with regenerative properties gold is used across both -contemporary and -ancient medicines. Here, we show that gold exerted these effects by enhancing the pool of pluripotent ELSC while improving their stemness. We used hESCs as an in-vitro model to understand if gold could enhance self-renewal and pluripotency. Swarna-bhasma (SB), an ancient Indian gold microparticulate (41.1 nm), preparation, reduced spontaneous-differentiation, improved self-renewal, pluripotency and proliferation of hESCs. Colloidal gold-nanoparticles (GNP) (15.59 nm) were tested to confirm that the observations were attributable to nanoparticulate-gold. SB and GNP exposure: maintained -stemness, -karyotypic stability, enhanced pluripotency till day-12, increased average colony-sizes, and reduced the number of autonomously-derived differentiated FGFR1 positive fibroblast-niche-cells/colony. Particulate-gold induced upregulation of FGFR1 and IGF2 expression, and decrease in IGF1 secretion indicates IGF1/2 mediated support for enhanced pluripotency and self-renewal in hESCs.

  6. Accumulation of Gold Nanoparticles in Brassic Juncea

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, A.T.; Haverkamp, R.G.; Davies, C.E.; Parsons, J.G.; Gardea-Torresdey, J.L.; Agterveld, D.van

    2009-06-03

    Enzymatic digestion is proposed as a method for concentrating gold nanoparticles produced in plants. The mild conditions of digestion are used in order to avoid an increase in the gold particle size, which would occur with a high-temperature process, so that material suitable for catalysis may be produced. Gold nanoparticles of a 5-50-nm diameter, as revealed by transmission electron microscopy (TEM), at concentrations 760 and 1120 ppm Au, were produced within Brassica juncea grown on soil with 22-48 mg Au kg{sup -1}. X-ray absorption near edge spectroscopy (XANES) reveals that the plant contained approximately equal quantities of Au in the metallic (Au{sup 0}) and oxidized (Au{sup +1}) states. Enzymatic digestion dissolved 55-60 wt% of the plant matter. Due to the loss of the soluble gold fraction, no significant increase in the total concentration of gold in the samples was observed. However, it is likely that the concentration of the gold nanoparticles increased by a factor of two. To obtain a gold concentration suitable for catalytic reactions, around 95 wt% of the starting dry biomass would need to be solubilized or removed, which has not yet been achieved.

  7. Accumulation of gold nanoparticles in Brassic juncea.

    Science.gov (United States)

    Marshall, Aaron T; Haverkamp, Richard G; Davies, Clive E; Parsons, Jason G; Gardea-Torresdey, Jorge L; van Agterveld, Dimitri

    2007-01-01

    Enzymatic digestion is proposed as a method for concentrating gold nanoparticles produced in plants. The mild conditions of digestion are used in order to avoid an increase in the gold particle size, which would occur with a high-temperature process, so that material suitable for catalysis may be produced. Gold nanoparticles of a 5-50-nm diameter, as revealed by transmission electron microscopy (TEM), at concentrations 760 and 1120 ppm Au, were produced within Brassica juncea grown on soil with 22-48 mg Au kg(-1). X-ray absorption near edge spectroscopy (XANES) reveals that the plant contained approximately equal quantities of Au in the metallic (Au0) and oxidized (Au+1) states. Enzymatic digestion dissolved 55-60 wt% of the plant matter. Due to the loss of the soluble gold fraction, no significant increase in the total concentration of gold in the samples was observed. However, it is likely that the concentration of the gold nanoparticles increased by a factor of two. To obtain a gold concentration suitable for catalytic reactions, around 95 wt% of the starting dry biomass would need to be solubilized or removed, which has not yet been achieved.

  8. Gold nanoparticles produced in a microalga

    Science.gov (United States)

    Luangpipat, Tiyaporn; Beattie, Isabel R.; Chisti, Yusuf; Haverkamp, Richard G.

    2011-12-01

    An efficient biological route to production of gold nanoparticles which allows the nanoparticles to be easily recovered remains elusive. Live cells of the green microalga Chlorella vulgaris were incubated with a solution of gold chloride and harvested by centrifugation. Nanoparticles inside intact cells were identified by transmission electron microscopy and confirmed to be metallic gold by synchrotron based X-ray powder diffraction and X-ray absorption spectroscopy. These intracellular gold nanoparticles were 40-60 nm in diameter. At a concentration of 1.4% Au in the alga, a better than 97% recovery of the gold from solution was achieved. A maximum of 4.2% Au in the alga was obtained. Exposure of C. vulgaris to solutions containing dissolved salts of palladium, ruthenium, and rhodium also resulted in the production of the corresponding nanoparticles within the cells. These were surmised to be also metallic, but were produced at a much lower intracellular concentration than achieved with gold. Iridium was apparently toxic to the alga. No nanoparticles were observed using platinum solutions. C. vulgaris provides a possible route to large scale production of gold nanoparticles.

  9. Gel Electrophoresis of Gold-DNA Nanoconjugates

    Directory of Open Access Journals (Sweden)

    T. Pellegrino

    2007-01-01

    Full Text Available Gold-DNA conjugates were investigated in detail by a comprehensive gel electrophoresis study based on 1200 gels. A controlled number of single-stranded DNA of different length was attached specifically via thiol-Au bonds to phosphine-stabilized colloidal gold nanoparticles. Alternatively, the surface of the gold particles was saturated with single stranded DNA of different length either specifically via thiol-Au bonds or by nonspecific adsorption. From the experimentally determined electrophoretic mobilities, estimates for the effective diameters of the gold-DNA conjugates were derived by applying two different data treatment approaches. The first method is based on making a calibration curve for the relation between effective diameters and mobilities with gold nanoparticles of known diameter. The second method is based on Ferguson analysis which uses gold nanoparticles of known diameter as reference database. Our study shows that effective diameters derived from gel electrophoresis measurements are affected with a high error bar as the determined values strongly depend on the method of evaluation, though relative changes in size upon binding of molecules can be detected with high precision. Furthermore, in this study, the specific attachment of DNA via gold-thiol bonds to Au nanoparticles is compared to nonspecific adsorption of DNA. Also, the maximum number of DNA molecules that can be bound per particle was determined.

  10. Phytomining for Artisanal Gold Mine Tailings Management

    Directory of Open Access Journals (Sweden)

    Baiq Dewi Krisnayanti

    2016-08-01

    Full Text Available Mine tailings are generally disposed of by artisanal and small scale gold miners in poorly constructed containment areas and this leads to environmental risk. Gold phytomining could be a possible option for tailings management at artisanal and small-scale gold mining (ASGM locations where plants accumulate residual gold in their above ground biomass. The value of metal recovered from plants could offset some of the costs of environmental management. Getting gold into plants has been repeatedly demonstrated by many research groups; however, a simple working technology to get gold out of plants is less well described. A field experiment to assess the relevance of the technology to artisanal miners was conducted in Central Lombok, Indonesia between April and June 2015. Tobacco was planted in cyanidation tailings (1 mg/kg gold and grown for 2.5 months before the entire plot area was irrigated with NaCN to induce metal uptake. Biomass was then harvested (100 kg, air dried, and ashed by miners in equipment currently used to ash activated carbon at the end of a cyanide leach circuit. Borax and silver as a collector metal were added to the tobacco ash and smelted at high temperature to extract metals from the ash. The mass of the final bullion (39 g was greater than the mass of silver used as a collector (31 g, indicating recovery of metals from the biomass through the smelt process. The gold yield of this trial was low (1.2 mg/kg dry weight biomass concentration, indicating that considerable work must still be done to optimise valuable metal recovery by plants at the field scale. However, the described method to process the biomass was technically feasible, and represents a valid technique that artisanal and small-scale gold miners are willing to adopt if the economic case is good.

  11. The giant Kalgoorlie Gold Field revisited

    Directory of Open Access Journals (Sweden)

    Noreen Mary Vielreicher

    2016-05-01

    Direct timing constraints on gold mineralization indicate that Fimiston- and Mt Charlotte-style mineralization formed within a relative short period of time around 2.64 Ga, and, as such, support a model of progressive deformation of a rheologically heterogeneous rock package late in the structural history. Fluid characteristics, combined with the structural, metamorphic and absolute timing, support description of gold mineralization at the Golden Mile as orogenic and mesozonal, and this allows direct correlation with orogenic gold deposits worldwide, which classically formed during accretion along convergent margins throughout Earth history.

  12. Gold Photoluminescence Wavelength and Polarization Engineering

    CERN Document Server

    Andersen, Sebastian K H; Bozhevolnyi, Sergey I

    2016-01-01

    We demonstrate engineering of the spectral content and polarization of photoluminescence (PL) from arrayed gold nanoparticles atop a subwavelength-thin dielectric spacer and optically-thick gold film, a configuration that supports gap-surface plasmon resonances (GSPRs). Choice of shapes and dimensions of gold nanoparticles influences the GSPR wavelength and polarization characteristics, thereby allowing us to enhance and spectrally mold the plasmon-assisted PL while simultaneously controlling its polarization. In order to understand the underlying physics behind the plasmon-enhanced PL, we develop a simple model that faithfully reproduces all features observed in our experiments showing also good quantitative agreement for the PL enhancement

  13. Gold versus stock investment: An econometric analysis

    Directory of Open Access Journals (Sweden)

    Martin Surya Mulyadi

    2012-06-01

    Full Text Available It is important to have a portfolio in investment to diversify the investment to different kinds of instruments. Based on previous research, it is concluded that gold is a good portfolio diversifier, a hedge against stock and safe haven in extreme stock market condition. As an investment instrument, stock is exposed to macroeconomic risks and global stock market risks. In this research, we conduct a comparison between the stock investment and gold investment by using the probit econometric model and data from 1997 to 2011. The final result obtained from the model shows that the gold investment is more advantageous than the stock investment.

  14. Resonance scattering spectroscopy of gold nanoparticle

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The gold nanoparticles in diameter of 10-95 nm have been prepared by Frens procedure, all of which exhibit a resonance scattering peak at 580 nm. The mechanism of resonance scattering for gold nanoparticle has been considered according to the wave motion theory of nanoparticle in liquid. The principle of superamolecular interface energy band(SIEB) has been set up and utilized to explain the relationship between the diameter and colors for gold nanoparticle in liquid. A novel spectrophotometric ruler for the determination of the diameter has been proposed according to the relationship of the maximum absorption wavelength and diameter.

  15. Mechanical characterization of a single gold nanowire.

    Science.gov (United States)

    Chang, Ming; Liu, Xiaojun; Chang, Feng-Cheng; Deka, Juti R

    2013-08-01

    Mechanical properties of gold nanowires were individually determined in this investigation using a multifunctional nanomanipulator inside a scanning electron microscope (SEM). Gold nanowires were synthesized by an electrochemical deposition technique. Three different characterization techniques including tensile, buckling and bending tests were adapted to quantitatively determine Young's modulus, yield stress and failure stress of the gold nanowires. The mechanical characterizations show that the nanowires were highly flexible in nature. The excellent resilience and the ability to store elastic energy in these nanowires confirm their potential applications in nano electromechanical devices.

  16. Designing hollow nano gold golf balls.

    Science.gov (United States)

    Landon, Preston B; Mo, Alexander H; Zhang, Chen; Emerson, Chris D; Printz, Adam D; Gomez, Alan F; DeLaTorre, Christopher J; Colburn, David A M; Anzenberg, Paula; Eliceiri, Matthew; O'Connell, Connor; Lal, Ratnesh

    2014-07-09

    Hollow/porous nanoparticles, including nanocarriers, nanoshells, and mesoporous materials have applications in catalysis, photonics, biosensing, and delivery of theranostic agents. Using a hierarchical template synthesis scheme, we have synthesized a nanocarrier mimicking a golf ball, consisting of (i) solid silica core with a pitted gold surface and (ii) a hollow/porous gold shell without silica. The template consisted of 100 nm polystyrene beads attached to a larger silica core. Selective gold plating of the core followed by removal of the polystyrene beads produced a golf ball-like nanostructure with 100 nm pits. Dissolution of the silica core produced a hollow/porous golf ball-like nanostructure.

  17. Gold in the past, today and future

    OpenAIRE

    Rudolf, R; Anžel, M.; Marković, E.; M. Čolić; D. Stamenković

    2012-01-01

    This paper deals with gold, which is described as a chemical element. Special attention is paid to its physical-chemical properties and, furthermore, where or in what form it can be found in nature. We discuss the role it has played through history and we inform how gold has been developed to the level it has reached today’s value. Still more, when gold is broken into nanoparticles, this form could be highly useful for a wide range of processes, including general nanotechnology, electronics m...

  18. 33 CFR 13.01-10 - Gold and silver bars.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Gold and silver bars. 13.01-10... DECORATIONS, MEDALS, RIBBONS AND SIMILAR DEVICES Gold and Silver Lifesaving Medals, Bars, and Miniatures § 13.01-10 Gold and silver bars. No person shall receive more than one Gold Lifesaving Medal and...

  19. Gold deposit styles and placer gold characterisation in northern and east-central Madagascar

    Science.gov (United States)

    Pitfield, Peter E. J; Styles, Michael T.; Taylor, Cliff D.; Key, Roger M.; Bauer,; Ralison, A

    2009-01-01

    Microchemical characterisation of bedrock and placer gold grains from six gold districts within the Archaean domains and intervening Neoproterozoic Anaboriana-Manampotsy belt of northern and east-central Madagascar show few opaque inclusions (e.g pyrrhotite, Bi tellurides) but wide range of Ag contents (40wt%). Some districts exhibit multiple source populations of grains. The ‘greenstone belt’ terranes have an orogenic gold signature locally with an intrusion-related to epithermal overprint. Proterozoic metasediments with felsic to ultramafic bodies yield dominantly intrusion-related gold. A high proportion of secondary gold (<0.5wt% Ag) is related to recycling of paleoplacers and erosion of post-Gondwana planation surfaces and indicates that some mesothermal gold systems were already partially to wholly removed by erosion by the PermoTriassic.

  20. Uptake and recovery of gold by immobilized persimmon tannin.

    Science.gov (United States)

    Nakajima, A; Sakaguchi, T

    1993-01-01

    Some attempts were made to recover gold from aqueous systems using immobilized persimmon tannin. This adsorbent adsorbed gold from solutions containing hydrogen tetrachloroaurate (III) with high efficiency, whereas there was minimal adsorption from solutions containing gold(I) sodium thiomalate and sodium dicyanoaurate(I). The adsorption of gold was rapid, and was affected by the pH of the solution, temperature, external gold concentration and amount of adsorbent. Adsorbed gold was easily desorbed with 1 mol dm-3 thiourea solution, indicating that immobilized persimmon tannin can be repeatedly re-used for the recovery of gold using adsorption-desorption cycles.

  1. Gold nanodumbbell-seeded growth of silver nanobars and nanobipyramids

    Science.gov (United States)

    Deng, Jin-Pei; Chen, Chih-Wei; Hsieh, Wei-Chi; Wang, Chao-Hsien; Hsu, Cheng-Yung; Lin, Jyun-Hao

    2014-03-01

    Gold nanodumbbells (NDs) are prepared by the reduction of gold ions in the presence of gold nanorods. Gold NDs are then employed for the synthesis of gold-silver core-shell nanoparticles (Au@Ag NPs). The quasi-ellipsoidal NPs could be found at room temperature, but Au@Ag bar and triangular bipyramid (TBP) NPs were obtained at 75 °C. Our results show that the long ends of gold NDs are in the position of the bar center and closely paralleled the shorter edge of TBP. Mechanisms in the growth of silver on gold NDs are proposed for the formations of these Au@Ag NPs.

  2. Source Strata of Gold in Western Guangdong—Their Identification and Significance in Gold Mineralization

    Institute of Scientific and Technical Information of China (English)

    陆建军; 吴劲薇; 等

    1995-01-01

    Strata of different geological periods extensively outcrop in western Guang-dong Province, but most gold deposits are restricted to the Middle-Late Proterozoic Yunkai Group and the Cambrian Bacun Group,showing obvious strata-boun character-istics .Gold abundance and trace element geochemistry of the Yunkai and Bacun Groups are compared with those of the Ordovician and Silurian strta.The Yunkai Group is considered to be the source strata for gold mineralization in the region.

  3. Gold revolution--gold nanoparticles for modern medicine and surgery.

    Science.gov (United States)

    Rippel, Radoslaw A; Seifalian, Alexander M

    2011-05-01

    Nanotechnology is a new and exciting branch of science which offers enormous potential for development of medicine and surgery. Gold nanoparticles (GNP) is just one of a variety of nano products which will be available for physician of the future. GNP will give us more effective treatments and diagnosis. We are able to conjugate GNP with peptides, drugs, and other molecules to gain astonishing effects. High quality, non-invasive imaging will inevitably lead to astonishing accuracy diagnostic tools with effective use during surgery. The same principles may be used in the future for drug delivery and thermal treatment of cancer. Detailed DNA detection and regulation may become everyday use technology, in medicine with support from GNP based tools. Bacterial diagnostics and nerve repair are relatively poorly researched areas of application of GNP with possibly astonishing therapeutic effects. Non-invasive clearance of arteriosclerotic plagues with GNP shows a great prospect for further development of minimally invasive surgery. However, before all of those tools will become available for clinicians, in depth toxicology research as well as transitional research and design have to be done to ensure safe clinical practice with maximal benefit for patients.

  4. [Determination of alkyl-phenols in textiles by in-tube capillary solid-phase extraction-gas chromatography].

    Science.gov (United States)

    Zhang, Luohong; Du, Ting; Zhong, Jiayu

    2015-10-01

    An in-tube capillary solid-phase extraction (SPE) -gas chromatography (GC) method was developed for confirmation and quantitative determination of octylphenol (OP) and nonylphenol (NP) in textiles. To make the in-tube capillary SPE column, the best SPE cartridge was chosen from four kinds of SPE cartridges. The adsorbent in the cartridge was used as the filling material to make the in-tube capillary SPE column. The nature, volume used, flow rate and adsorption capacity of the eluent were compared. Finally, the in-tube capillary solid-phase extraction was combined with gas chromatography to detect the alkyl phenols (APs). Abselut NEXUS extraction cartridge was chosen as the best solid phase extractant. The optimal in-tube capillary SPE extraction conditions were as follows: 1.2 μL methanol and 1.2 μL ultra-pure water for activating the extraction column, 1.2 μL methanol for eluting, 0.4 μL/min for solution loading. The method showed a good linear relationship in the low concentration range, and the enrichment ratios for the APs were about 100 times. The detection limits of octylphenol and nonylphenol were 3.7 μg/L and 4.5 μg/L, respectively. The recoveries of octylphenol were 85.6%-98.2%, and those of nonylphenol were 83.8%-95.7%. The experimental results demonstrated that the method is simple, rapid, and useful for detecting APs in textiles.

  5. Structural controls on Carlin-type gold mineralization in the gold bar district, Eureka County, Nevada

    Science.gov (United States)

    Yigit, O.; Nelson, E.P.; Hitzman, M.W.; Hofstra, A.H.

    2003-01-01

    The Gold Bar district in the southern Roberts Mountains, 48 km northwest of Eureka, Nevada, contains one main deposit (Gold Bar), five satellite deposits, and other resources. Approximately 0.5 Moz of gold have been recovered from a resource of 1,639,000 oz of gold in Carlin-type gold deposits in lower plate, miogeoclinal carbonate rocks below the Roberts Mountains thrust. Host rocks are unit 2 of the Upper Member of the Devonian Denay Formation and the Bartine Member of the McColley Canyon Formation. Spatial and temporal relations between structures and gold mineralization indicate that both pre-Tertiary and Tertiary structures were important controls on gold mineralization. Gold mineralization occurs primarily along high-angle Tertiary normal faults, some of which are reactivated reverse faults of Paleozoic or Mesozoic age. Most deposits are localized at the intersection of northwest- and northeast-striking faults. Alteration includes decalcification, and to a lesser extent, silicification along high-angle faults. Jasperoid (pervasive silicification), which formed along most faults and in some strata-bound zones, accounts for a small portion of the ore in every deposit. In the Gold Canyon deposit, a high-grade jasperoid pipe formed along a Tertiary normal fault which was localized along a zone of overturned fault-propagation folds and thrust faults of Paleozoic or Mesozoic age.

  6. Direct formation of gold nanorods on surfaces using polymer-immobilised gold seeds

    OpenAIRE

    Abyaneh, Majid K; Pietro Parisse; Loredana Casalis

    2016-01-01

    Herein, we present the formation of gold nanorods (GNRs) on novel gold–poly(methyl methacrylate) (Au–PMMA) nanocomposite substrates with unprecedented growth control through the polymer molecular weight (Mw) and gold-salt-to-polymer weight ratio. For the first time, GNRs have been produced by seed-mediated direct growth on surfaces that were pre-coated with polymer-immobilised gold seeds. A Au–PMMA nanocomposite formed by UV photoreduction has been used as the gold seed. The influence of poly...

  7. Epithermal Gold Mineralization in Chinese Tianshan Province

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Tianshan is a part of the complex system of orogenic belts of Phanerozoic in Central Asia. In the northwestern Chinese Tianshan, Borohoro range, the major metallogenic belt in this area is situated between the Yili block and Keguqinshan-Sairim uplift. The intra-arc basins resulting from southward subduction of the Junggar plate and accompanying volcanism are the essential factors for the formation of the hydrothermal system that caused gold mineralization. The adularia-sericite-style epithermal Arxi gold deposit formed in an extensional tectonic setting. In the eastern Tianshan, post-orogenic magmatism resulted in a hydrothermai system that produced the epithermai Xitan gold deposit. Both gold deposits are related to local extensional setting, although differences exist in their timing and location.

  8. Adsorption-induced restructuring of gold nanochains

    DEFF Research Database (Denmark)

    Bahn, Sune Rastad; Lopez, Nuria; Nørskov, Jens Kehlet;

    2002-01-01

    The chemical properties of single-atomic chains of gold atoms are investigated using density functional calculations. The nanochains are shown to be unusually chemically active with strong chemisorption of oxygen atoms and carbon monoxide. The chemisorption energies vary significantly...

  9. Preparation of Gold Nanoparticles Protected with Polyelectrolyte

    Institute of Scientific and Technical Information of China (English)

    Xu Ping SUN; Zhe Ling ZHANG; Bai Lin ZHANG; Xian Dui DONG; Shao Jun DONG; Er Kang WANG

    2003-01-01

    Gold nanoparticles were synthesized through the reduction of tetrachlorauric acid (HAuCl4) by NaBH4, with polyethyleneimine(PEI) as stabilizer. The nanoparticles were characterized by UV-vis spectroscopy and atomic force microscopy(AFM).

  10. Gold in the past, today and future

    Directory of Open Access Journals (Sweden)

    R. Rudolf

    2012-04-01

    Full Text Available This paper deals with gold, which is described as a chemical element. Special attention is paid to its physical-chemical properties and, furthermore, where or in what form it can be found in nature. We discuss the role it has played through history and we inform how gold has been developed to the level it has reached today’s value. Still more, when gold is broken into nanoparticles, this form could be highly useful for a wide range of processes, including general nanotechnology, electronics manufacturing and the synthesizing of different functional materials. It is important that we know that gold is also used in industry in many engineering applications (contacts in micro-electronics and medicine (dental alloys, implants.

  11. Stabilizer-free nanosized gold sols.

    Science.gov (United States)

    Andreescu, Daniel; Sau, Tapan Kumar; Goia, Dan V

    2006-06-15

    The paper describes a convenient, rapid, and reproducible method for the synthesis of stable dispersions of uniform gold nanoparticles at ambient temperatures by mixing aqueous solutions of tetrachloroauric acid and iso-ascorbic acid. The influence of the experimental conditions on the size of the gold particles and the stability of the final sols was monitored by dynamic light scattering and UV-vis spectrophotometry. It was found that the size of the resulting nanoparticles is affected by the concentration and the pH of gold solution, while the stability of the electrostatically stabilized final sols is strongly dependent on the excess of reductant in the system, the ionic strength, and the temperature of the precipitation. Since the preparation process does not require the addition of a dispersing agent, the surface of the resulting gold nanoparticles can be easily functionalized to make them suitable for applications in medicine, biology, and catalysis.

  12. Willingness to Open Islamic Gold Investment Accounts

    National Research Council Canada - National Science Library

    Hanudin Amin

    2016-01-01

    .... This study extends the applicability of the Theory of Reasoned Action (TRA) to Islamic gold investment accounts and includes three additional factors namely perceived financial benefit, consumer religiosity and consumer information...

  13. Alaska gold rush trails study: Preliminary draft

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Preliminary study draft, with maps, of seven gold rush trails in Alaska, to determine suitability for inclusion in the National Scenic Trails system and their...

  14. Deep gold mine fracture zone behaviour

    CSIR Research Space (South Africa)

    Napier, JAL

    1998-12-01

    Full Text Available The investigation of the behaviour of the fracture zone surrounding deep level gold mine stopes is detailed in three main sections of this report. Section 2 outlines the ongoing study of fundamental fracture process and their numerical...

  15. Is Farmland As Good As Gold?

    Directory of Open Access Journals (Sweden)

    Marvin J. Painter

    2011-01-01

    Full Text Available An analysis of Canadian farmland risk and its return on investment shows that a Farmland Real Estate Investment Trust (F-REIT and gold would have significantly enhanced portfolio performance over the past 35 years. Investors who desire low-risk portfolios would not have benefited from an F-REIT or gold investment. However, investors in the medium-risk category could have improved the financial performance of their portfolios by including an F-REIT investment rather than gold. The financial gains from F-REIT result from a level of risk that is lower than gold, REITs, and stocks, an expected yield that is greater than for bonds, and a low correlation with other financial asset returns.

  16. Interaction of Saccharomyces cerevisiae with gold: toxicity and accumulation.

    Science.gov (United States)

    Karamushka, V I; Gadd, G M

    1999-12-01

    This paper examines the effects of ionic gold on Saccharomyces cerevisiae, as determined by long-term (growth in gold-containing media) and short-term interactions (H+ efflux activity). An increasing gold concentration inhibited growth and at gold concentration used. Both Ca and Mg enhanced the inhibitory effect of gold on the yeast cells with Ca showing a stronger inhibitory effect than Mg.

  17. The Modern Monetary System and Gold

    Directory of Open Access Journals (Sweden)

    N N Rubtsov

    2013-12-01

    Full Text Available The article considers the nature of modern money, analyzes the mechanism of its creation, showing that it is basically generated by credit and the principle of partial bank reserve. The article draws comparative parallels between trade money based on gold and contemporary, credit money; the author quotes leading bankers and finance experts on the need for partial return to the principles of functioning of the gold standard as the most effective institute of regulating the monetary system in society.

  18. Silver and gold-catalyzed multicomponent reactions

    Directory of Open Access Journals (Sweden)

    Giorgio Abbiati

    2014-02-01

    Full Text Available Silver and gold salts and complexes mainly act as soft and carbophilic Lewis acids even if their use as σ-activators has been rarely reported. Recently, transformations involving Au(I/Au(III-redox catalytic systems have been reported in the literature. In this review we highlight all these aspects of silver and gold-mediated processes and their application in multicomponent reactions.

  19. PIXE analysis of Trojan gold jewelry

    Science.gov (United States)

    Swann, C. P.; Betancourt, P. P.; Fleming, S.; Floyd, C. R.

    1997-07-01

    Technological advancements in the production of gold jewelry from the Troad in northwest Anatolia in the third millennium BC are investigated by PIXE. Results indicate a higher percentage of Cu at the interface between joined pieces of gold than exists elsewhere on the jewelry, away from joinings. The results indicate the probable use of copper salts as a flux in the manufacture of jewelry with granulation.

  20. Nonlinear photoluminescence spectrum of single gold nanostructures.

    Science.gov (United States)

    Knittel, Vanessa; Fischer, Marco P; de Roo, Tjaard; Mecking, Stefan; Leitenstorfer, Alfred; Brida, Daniele

    2015-01-27

    We investigate the multiphoton photoluminescence characteristics of gold nanoantennas fabricated from single crystals and polycrystalline films. By exciting these nanostructures with ultrashort pulses tunable in the near-infrared range, we observe distinct features in the broadband photoluminescence spectrum. By comparing antennas of different crystallinity and shape, we demonstrate that the nanoscopic geometry of plasmonic devices determines the shape of the emission spectra. Our findings rule out the contribution of the gold band structure in shaping the photoluminescence.

  1. Radiochemical separation of gold by amalgam exchange

    Science.gov (United States)

    Ruch, R.R.

    1970-01-01

    A rapid and simple method for the radiochemical separation of gold after neutron activation. The technique is based on treatment with a dilute indium-gold amalgam, both chemical reduction and isotopic exchange being involved. The counting efficiency for 198Au in small volumes of the amalgam is good. Few interferences occur and the method is applicable to clays, rocks, salts and metals. The possibility of determining silver, platinum and palladium by a similar method is mentioned. ?? 1970.

  2. Optical Epitaxial Growth of Gold Nanoparticle Arrays.

    Science.gov (United States)

    Huang, Ningfeng; Martínez, Luis Javier; Jaquay, Eric; Nakano, Aiichiro; Povinelli, Michelle L

    2015-09-09

    We use an optical analogue of epitaxial growth to assemble gold nanoparticles into 2D arrays. Particles are attracted to a growth template via optical forces and interact through optical binding. Competition between effects determines the final particle arrangements. We use a Monte Carlo model to design a template that favors growth of hexagonal particle arrays. We experimentally demonstrate growth of a highly stable array of 50 gold particles with 200 nm diameter, spaced by 1.1 μm.

  3. Analysis on the Impact of the Fluctuation of the International Gold Prices on the Chinese Gold Stocks

    Directory of Open Access Journals (Sweden)

    Jiankang Jin

    2014-01-01

    Full Text Available Five gold stocks in Chinese Shanghai and Shenzhen A-share and Comex gold futures are chosen to form the sample, for the purpose of analysing the impact of the fluctuation of the international gold prices on the gold stocks in Chinese Shanghai and Shenzhen A-share. Using the methods of unit root test, Granger causality test, VAR model, and impulse response function, this paper has analysed the relationship between the price change of the international gold futures and the price fluctuation of gold stocks in Chinese Shanghai and Shenzhen comprehensively. The results suggest the fluctuation of the international gold futures has a strong influence on the domestic futures.

  4. Functionalization of gold nanoparticles as antidiabetic nanomaterial.

    Science.gov (United States)

    Venkatachalam, M; Govindaraju, K; Mohamed Sadiq, A; Tamilselvan, S; Ganesh Kumar, V; Singaravelu, G

    2013-12-01

    In the present investigation, functionalization of gold nanoparticles synthesized using propanoic acid 2-(3-acetoxy-4,4,14-trimethylandrost-8-en-17-yl) (PAT) an active biocomponent isolated from Cassia auriculata is studied in detail. On reaction of PAT with aqueous HAuCl4, rapid formation of stable gold nanoparticles was achieved. Formation of gold nanoparticles was confirmed by UV-vis spectroscopy, XRD, GC-MS,FTIR, TEM and SEM with EDAX. Gold nanoparticles mostly were monodisperse, spherical in shape and ranged in size 12-41 nm. Gold nanoparticles synthesised using PAT was administered to alloxan (150 mg/kg body weight) induced diabetic male albino rats at different doses (0.25, 0.5, 0.75 and 1.0mg/kg body weight) for 28 days. Plasma glucose level, cholesterol and triglyceride were significantly (pgold nanoparticles at dosage of 0.5mg/kg body weight and plasma insulin increased significantly. The newly genre green gold nanoparticles exhibit remarkable protein tyrosine phosphatase 1B inhibitory activity.

  5. Gold mobility during Palaeoarchaean submarine alteration

    Science.gov (United States)

    Hofmann, Axel; Pitcairn, Iain; Wilson, Allan

    2017-03-01

    Seafloor alteration provides large amounts of solutes to the hydrosphere. In order to investigate gold mobility during water-rock interaction prior to 3-billion-years ago, low detection limit analysis of Au concentrations was carried out on rocks from marine alteration zones. Stratiform zones recording low-temperature (≤150 °C) seafloor alteration are a characteristic feature of greenstone belts older than 3.0 Ga. Hydrothermal processes were operating on, and immediately below, the seafloor, giving rise to extensive silicification of sub-seafloor volcanic rocks and silicification of seafloor sediments. In order to investigate gold mobility during silicification, unaltered and variably silicified volcanic rocks and associated cherts from Palaeoarchaean greenstone successions (c. 3.4 Ga) of South Africa were analyzed. Results show mobility of gold during silicification of mafic/ultramafic rocks and transfer to the Archaean ocean. Some gold was incorporated into carbonaceous marine sediments overlying the alteration zones. A combination of pervasive silicification, rarity of black shales, and low gold content in komatiites can explain the low mineralization potential of Palaeoarchaean greenstone belts for orogenic gold deposits.

  6. The gold rush 1925-35.

    Science.gov (United States)

    Keers, R Y

    1980-12-01

    Although from the time of Koch onwards there had been desultory experiments with a variety of gold preparations in the management of pulmonary tuberculosis, gold as a recognised and accepted treatment did not emerge until 1925. In that year Holger Mollgaard of Copenhagen introduced sanocrysin, a double thiosulphate of gold and sodium, with which he had conducted an extensive series of animal experiments. The results of these were considered to justify its use in clinical practice and two physicians, Secher and Faber, undeterred by its toxicity, reported enthusiastically in its favour. Other Danish physicians followed but, alarmed by violent reactions, modified the dosage, an example followed by British workers. Encouraging results continued to be reported although each series contained a significant proportion of failures, and toxicity remained high. The first properly planned and fully controlled clinical trial took place in the United States and produced a report which was wholly adverse and which sounded the death knell of gold therapy throughout America. Until 1934-35 gold was used extensively in Europe but thereafter there was a sudden and largely universal cessation of interest and within a few years gold, introduced with such éclat and carrying so many high hopes, had vanished from the therapy of tuberculosis even though, at that point, no better alternative was available.

  7. Gold grade distribution within an epithermal quartz vein system, Kestanelik, NW Turkey: implications for gold exploration

    Science.gov (United States)

    Gulyuz, Nilay; Shipton, Zoe; Gulyuz, Erhan; Lord, Richard; Kaymakci, Nuretdin; Kuscu, İlkay

    2017-04-01

    Vein-hosted gold deposits contribute a large part to the global gold production. Discovery of these deposits mainly include drilling of hundreds of holes, collecting thousands of soil and rock samples and some geophysical surveys which are expensive and time consuming. Understanding the structures hosting the veins and the variations in gold concentrations within the veins is crucial to constrain a more economic exploration program. The main aim of this study is to investigate the gold grade distribution in the mineralized quartz veins of a well exposed epithermal gold deposit hosted by Paleozoic schist and Eocene quartz-feldspar-hornblende porphyry in Lapseki, NW Turkey. We have constructed 3D architecture of the vein surfaces by mapping their outcrop geometries using a highly sensitive Trimble GPS, collecting detailed field data, well-logs and geochemistry data from 396 drill holes (255 diamond cut and 141 reverse circulation holes). Modelling was performed in MOVE Structural Modelling and Analysis software granted by Midland Valley's Academic Software Initiative, and GIS application softwares Global Mapper and Esri-ArcGIS. We envisaged that while fluid entering the conduit ascents, a sudden thickness increase in the conduit would lead to a drop in the fluid pressure causing boiling (the most dominant gold precipitation mechanism) and associated gold precipitation. Regression analysis was performed between the orthogonal thickness values and gold grades of each vein, and statistical analyses were performed to see if the gold is concentrated at specific structural positions along dip. Gold grades in the alteration zones were compared to those in the adjacent veins to understand the degree of mineralization in alteration zones. A possible correlation was also examined between the host rock type and the gold grades in the veins. These studies indicated that gold grades are elevated in the adjacent alteration zones where high gold grades exist in the veins. Schist

  8. Crystal structure of gold hydride

    Energy Technology Data Exchange (ETDEWEB)

    Degtyareva, Valentina F., E-mail: degtyar@issp.ac.ru

    2015-10-05

    Highlights: • Volume expansion of metal hydrides is due to the increase in the s-band filling. • AuH structure is similar to that of Hg having one more s electron compared to Au. • Structure stability of both Hg and AuH is governed by the Hume-Rothery rule. - Abstract: A number of transition metal hydrides with close-packed metal sublattices of fcc or hcp structures with hydrogen in octahedral interstitial positions were obtained by the high-pressure-hydrogen technique described by Ponyatovskii et al. (1982). In this paper we consider volume increase of metals by hydrogenation and possible crystal structure of gold hydride in relation with the structure of mercury, the nearest neighbor of Au in the Periodic table. Suggested structure of AuH has a basic tetragonal body-centered cell that is very similar to the mercury structure Hg-t I 2. The reasons of stability for this structure are discussed within the model of Fermi sphere–Brillouin zone interactions.

  9. Curcumin: the Indian solid gold.

    Science.gov (United States)

    Aggarwal, Bharat B; Sundaram, Chitra; Malani, Nikita; Ichikawa, Haruyo

    2007-01-01

    Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

  10. [Sunrise gold foil jacket crown].

    Science.gov (United States)

    Lecardonnel, A

    1989-09-01

    This technique permits the preparation of ceramic jacket crowns made on Sunrise laminated precious metal alloy. The Sunrise foil is gold-colored, made of 99% of precious metals and is 50 microns thick. The die is prepared in order to display a moderate and regular undercut beyond the cervical limit. The margin will be underlined with a red pencil. The Sunrise foil is cut according to predetermined templates. Then the foil is applied without burnishing, according to the technique of jacket crowns on platinum foil only by finger pressure. The double folding on closure is preferably done distally or mesially. Then, the metal base is disinserted, sandblasted with 100 microns aluminum oxide, replaced on its die, and placed in a rubber casing before being placed in the isostatic press, to be subjected to a pressure of 2,000 TSI (14 kg par cm2). Sunrise's orange color reinforces rather subtetly the overall color, making these reconstructions particularly esthetic. The color of the Sunrise metal does not require, therefore a too thick opaque. Any ceramic intended to be fired on a metal base, may be used in respecting its firing protocol. Sunrise, as any other technique of this type, require a careful preparation with a shoulder that has a rounded gingivoaxial line angle. Bridges may be built on the "thimbles" crowns, fitted on Sunrise cores, the pontics being made as a ceramo-metal framework.

  11. A thermally stable gold(III) hydride: synthesis, reactivity, and reductive condensation as a route to gold(II) complexes.

    Science.gov (United States)

    Roşca, Dragoş-Adrian; Smith, Dan A; Hughes, David L; Bochmann, Manfred

    2012-10-15

    Going for gold: The first thermally stable gold(III) hydride [(C N C)*AuH] is presented. It undergoes regioselective insertions with allenes to give gold(III) vinyl complexes, and reductive condensation with [(C N C)*AuOH] to the air-stable Au(II) product, [(C N C)*(2)Au(2)], with a short nonbridged gold-gold bond.

  12. Performance of multi tubes in tube helically coiled as a compact heat exchanger

    Science.gov (United States)

    Nada, S. A.; El Shaer, W. G.; Huzayyin, A. S.

    2014-12-01

    Multi tubes in tube helically coiled heat exchanger is proposed as a compact heat exchanger. Effects of heat exchanger geometric parameters and fluid flow parameters; namely number of inner tubes, annulus hydraulic diameter, Reynolds numbers and input heat flux, on performance of the heat exchanger are experimentally investigated. Different coils with different numbers of inner tubes, namely 1, 3, 4 and 5 tubes, were tested. Results showed that coils with 3 inner tubes have higher values of heat transfer coefficient and compactness parameter (bar{h} Ah ). Pressure drop increases with increasing both of Reynolds number and number of inner tubes. Correlations of average Nusselt number were deduced from experimental data in terms of Reynolds number, Prandtl number, Number of inner coils tubes and coil hydraulic diameter. Correlations prediction was compared with experimental data and the comparison was fair enough.

  13. State of the Art Power-in Tube Niobium-Tin Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Godeke, A.; Ouden, A. Den; Nijhuis, A.; ten Kate, H.H.J.

    2008-06-01

    Powder-in-Tube (PIT) processed Niobium-Tin wires are commercially manufactured for nearly three decades and have demonstrated a combination of very high current density (presently up to 2500 A mm{sup -2} non-Cu at 12 T and 4.2 K) with fine (35 {micro}m), well separated filaments. We review the developments that have led to the present state of the art PIT Niobium-Tin wires, discuss the wire manufacturing and A15 formation processes, and describe typical superconducting performance in relation to magnetic field and strain. We further highlight successful applications of PIT wires and conclude with an outlook on possibilities for further improvements in the performance of PIT Niobium-Tin wires.

  14. State of the Art Power-in Tube Niobium-Tin Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Godeke, A.; Ouden, A. Den; Nijhuis, A.; ten Kate, H.H.J.

    2008-06-01

    Powder-in-Tube (PIT) processed Niobium-Tin wires are commercially manufactured for nearly three decades and have demonstrated a combination of very high current density (presently up to 2500 A mm{sup -2} non-Cu at 12 T and 4.2 K) with fine (35 {micro}m), well separated filaments. We review the developments that have led to the present state of the art PIT Niobium-Tin wires, discuss the wire manufacturing and A15 formation processes, and describe typical superconducting performance in relation to magnetic field and strain. We further highlight successful applications of PIT wires and conclude with an outlook on possibilities for further improvements in the performance of PIT Niobium-Tin wires.

  15. EVALUATION OF SEISMIC BEHAVIOR OF IRREGULAR TUBE BUILDINGS IN TUBE SYSTEMS

    Directory of Open Access Journals (Sweden)

    Hojat Allah Ghasemi

    2016-03-01

    Full Text Available Setbacks in the volume of a building usually arise from the demands of urban design for illumination, proportion, etc. However, in seismic events they are the cause of abrupt changes in stiffness and mass producing a concentration of stresses in the floors near the site of sudden change. In general terms, one should ensure that the transitions are as gradual as possible in order to avoid such concentration of stresses. This study is intended to investigate seismic behavior of irregular building tube in tube systems, for this purpose seismic behavior of 40-story and 60-story reinforced concrete frame building with irregular plan was evaluated, seismic behavior of irregular buildings was assessed by overall building drifts, story drifts and shear lag behavior factors.. Higher irregularities in the overall plan structure of a building increase the phenomena of story drift and shear lag phenomena. Story drift and shear lag are higher for 60-story building than for a 40-story building.

  16. Liquid antisolvent preparation of amorphous cefuroxime axetil nanoparticles in a tube-in-tube microchannel reactor.

    Science.gov (United States)

    Zhu, Wen-Zhen; Wang, Jie-Xin; Shao, Lei; Zhang, Hai-xia; Zhang, Qian-xia; Chen, Jian-Feng

    2010-08-16

    This article presents the preparation of nanoparticles of amorphous cefuroxime axetil (CFA) in a microporous tube-in-tube microchannel reactor (MTMCR). The experimental results indicated that CFA particle with a tunable size of 400-1400 nm could be achieved under a high throughput in the range of 1.5-6L/min. The average particle size decreased with increasing overall volumetric flow rate and decreasing CFA concentration, micropore size, and annular channel width. The produced CFA nanoparticles were characterized by SEM, XRD, FT-IR, DSC and a dissolution test, which indicated that the nanosized CFA was amorphous and exhibited higher dissolution rate compared to the raw CFA. The MTMCR might offer a general and facile pathway for mass production of the nanoparticles of hydrophobic pharmaceuticals thanks to its high throughput capacity and excellent micromixing performance.

  17. Subchronic inhalation toxicity of gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Chung Yong

    2011-05-01

    Full Text Available Abstract Background Gold nanoparticles are widely used in consumer products, including cosmetics, food packaging, beverages, toothpaste, automobiles, and lubricants. With this increase in consumer products containing gold nanoparticles, the potential for worker exposure to gold nanoparticles will also increase. Only a few studies have produced data on the in vivo toxicology of gold nanoparticles, meaning that the absorption, distribution, metabolism, and excretion (ADME of gold nanoparticles remain unclear. Results The toxicity of gold nanoparticles was studied in Sprague Dawley rats by inhalation. Seven-week-old rats, weighing approximately 200 g (males and 145 g (females, were divided into 4 groups (10 rats in each group: fresh-air control, low-dose (2.36 × 104 particle/cm3, 0.04 μg/m3, middle-dose (2.36 × 105 particle/cm3, 0.38 μg/m3, and high-dose (1.85 × 106 particle/cm3, 20.02 μg/m3. The animals were exposed to gold nanoparticles (average diameter 4-5 nm for 6 hours/day, 5 days/week, for 90-days in a whole-body inhalation chamber. In addition to mortality and clinical observations, body weight, food consumption, and lung function were recorded weekly. At the end of the study, the rats were subjected to a full necropsy, blood samples were collected for hematology and clinical chemistry tests, and organ weights were measured. Cellular differential counts and cytotoxicity measurements, such as albumin, lactate dehydrogenase (LDH, and total protein were also monitored in a cellular bronchoalveolar lavage (BAL fluid. Among lung function test measurements, tidal volume and minute volume showed a tendency to decrease comparing control and dose groups during the 90-days of exposure. Although no statistically significant differences were found in cellular differential counts, histopathologic examination showed minimal alveoli, an inflammatory infiltrate with a mixed cell type, and increased macrophages in the high-dose rats. Tissue

  18. Subchronic inhalation toxicity of gold nanoparticles.

    Science.gov (United States)

    Sung, Jae Hyuck; Ji, Jun Ho; Park, Jung Duck; Song, Moon Yong; Song, Kyung Seuk; Ryu, Hyeon Ryol; Yoon, Jin Uk; Jeon, Ki Soo; Jeong, Jayoung; Han, Beom Seok; Chung, Yong Hyun; Chang, Hee Kyung; Lee, Ji Hyun; Kim, Dong Won; Kelman, Bruce J; Yu, Il Je

    2011-05-14

    Gold nanoparticles are widely used in consumer products, including cosmetics, food packaging, beverages, toothpaste, automobiles, and lubricants. With this increase in consumer products containing gold nanoparticles, the potential for worker exposure to gold nanoparticles will also increase. Only a few studies have produced data on the in vivo toxicology of gold nanoparticles, meaning that the absorption, distribution, metabolism, and excretion (ADME) of gold nanoparticles remain unclear. The toxicity of gold nanoparticles was studied in Sprague Dawley rats by inhalation. Seven-week-old rats, weighing approximately 200 g (males) and 145 g (females), were divided into 4 groups (10 rats in each group): fresh-air control, low-dose (2.36 × 104 particle/cm3, 0.04 μg/m3), middle-dose (2.36 × 105 particle/cm3, 0.38 μg/m3), and high-dose (1.85 × 106 particle/cm3, 20.02 μg/m3). The animals were exposed to gold nanoparticles (average diameter 4-5 nm) for 6 hours/day, 5 days/week, for 90-days in a whole-body inhalation chamber. In addition to mortality and clinical observations, body weight, food consumption, and lung function were recorded weekly. At the end of the study, the rats were subjected to a full necropsy, blood samples were collected for hematology and clinical chemistry tests, and organ weights were measured. Cellular differential counts and cytotoxicity measurements, such as albumin, lactate dehydrogenase (LDH), and total protein were also monitored in a cellular bronchoalveolar lavage (BAL) fluid. Among lung function test measurements, tidal volume and minute volume showed a tendency to decrease comparing control and dose groups during the 90-days of exposure. Although no statistically significant differences were found in cellular differential counts, histopathologic examination showed minimal alveoli, an inflammatory infiltrate with a mixed cell type, and increased macrophages in the high-dose rats. Tissue distribution of gold nanoparticles showed a dose

  19. Tectonic setting of Late Cenozoic gold mineralization in the gold belt of Costa Rica

    Energy Technology Data Exchange (ETDEWEB)

    Deruyter, V.D.

    1985-01-01

    The Gold Belt of Costa Rica is a northwest-elongated zone 15 km wide by 120 km long containing numerous auriferous quartz veins and pyritic silicified patterns upon which abundant small mines are developed. Gold veins are related principally to northeast-southwest and north-south striking, steeply dipping faults. Higher grade ore and thicker veins invariably occur at intersections of these fracture orientations, indicating simultaneous opening at the time of gold introduction. Restriction of gold veins to the northwest-trending arc of Miocene Aguacate Group andesite volcanic rocks, a product of Cocos Plate subduction, suggested approximately coeval formation, but recognition by the writer of the important role played by 2-5 m.y. old altered, gold mineralized rhyolite dikes intruded along north-south gold vein structures and intimately involved with high grade ores at the Esperanza Mine and Rio Chiquito prospect, for example, suggest a much younger period of fracturing and gold introduction. The rhyolite intrusions are more brittle and stockwork mineralized than andesite host rocks and form bulk tonnage gold targets. Initiation of right-lateral movement along the north-south Panama Fracture Zone at 5 m.y.a. within the pattern of northeastward Cocos Plate subduction may have tapped rhyolites from subvolcanic magma chambers into new faults.

  20. Well-Defined Dinuclear Gold Complexes for Preorganization-Induced Selective Dual Gold Catalysis

    NARCIS (Netherlands)

    Vreeken, V.; Broere, D.L.J.; Jans, A.C.H.; Lankelma, M.; Reek, J.N.H.; Siegler, M.A.; van der Vlugt, J.I.

    2016-01-01

    The synthesis, reactivity, and potential of well-defined dinuclear gold complexes as precursors for dual gold catalysis are explored. Using the preorganizing abilities of the ditopic (PNPiPr)-P-H (L-H) ligand, dinuclear Au-I-Au-I complex 1 and mixed-valent Au-I-Au-III complex 2 provide access to str

  1. Knowledge-driven GIS modeling technique for gold exploration, Bulghah gold mine area, Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Ahmed A. Madani

    2011-12-01

    Full Text Available This research aims to generate a favorability map for gold exploration at the Bulghah gold mine area using integration of geo-datasets within a GIS environment. Spatial data analyses and integration of different geo-datasets are carried out based on knowledge-driven and weighting technique. The integration process involves the weighting and scoring of different layers affecting the gold mineralization at the study area using the index overlay method within PCI Geomatica environment. Generation of the binary predictor maps for lithology, lineaments, faults and favorable contacts precede the construction of the favorability map. About 100 m buffer zones are generated for favorable contacts, lineaments and major faults layers. Internal weighting is assigned to each layer based on favorability for gold mineralization. The scores for lithology, major faults, lineaments and favorable contacts layers in the constructed favorability map are 50%, 25%, 10% and 15%, respectively. Final favorability map for the Bulghah gold mine area shows the recording of two new sites for gold mineralization located at the northern and southern extensions of tonalite–diorite intrusions. The northern new site is now exploited for gold from the Bulghah North mine. The southern new site is narrow and small; its rocks resemble those of the Bulghah gold mine.

  2. Coupling reaction on gold nanoparticle to yield polythiophene/gold nanoparticle alternate network film.

    Science.gov (United States)

    Tanaka, Manabu; Fujita, Remi; Nishide, Hiroyuki

    2009-01-01

    The novel gold nanoparticle, which was stabilized with pi-conjugated molecules bearing functional groups at the terminals, was prepared via conventional procedure by using 5-bromo-2,2'-bithiophene-5'-thiol as a stabilizer. The gold nanoparticle (ca. 3 nm-diameter) showed good dispersion stability in various organic solvents, and its electrochemical and spectroscopic study revealed peculiar properties originated in the pi-conjugated molecular stabilizer, bithiophene derivative. The Pd-catalyzed coupling reaction on the gold nanoparticle was first achieved by using the gold nanoparticle bearing bromo groups at the particle surface and the model boronic acid molecule, 5-formyl-2-thiopheneboronic acid, to yield the terthiophene derivatives on the gold nanoparticle. The 1H-NMR, UV, and TGA analysis supported the progress of the coupling reaction on the gold nanoparticle. This Pd-catalyzed coupling reaction was applied with the borate-terminated polythiophene to form polythiophene/gold nanoparticle alternate network film. The electron microscopic images supported the formation of the network structure. The high electric conductivity on the network film suggested that the conductive characteristic of the film originated from that of the pi-conjugated polythiophene backbone connected with the gold nanoparticle.

  3. China Gold Group Invested 2.18 billion Yuan to Buy Gold Mine

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Ministry of Finance recently proclaimed that China Gold Group has invested 2.18 billion Yuan to gain the exploration right on the Yang- shan gold mine in Wen County,Gansu Prov- ince.Yangshan is located at the place where

  4. Blood gold concentrations in children with juvenile rheumatoid arthritis undergoing long-term oral gold therapy.

    Science.gov (United States)

    Giannini, E H; Brewer, E J; Person, D A

    1984-04-01

    During an uncontrolled, open-labelled, open-ended clinical trial of auranofin in children with juvenile rheumatoid arthritis (JRA) we obtained serial blood samples for the purpose of assessing gold content. Our objectives were (1) to observe the pattern of blood gold concentrations over a period of time in children undergoing long-term oral gold therapy, and (2) to observe the effect of changing dosage levels on blood gold concentrations. The initial dosage of auranofin was 0.1 mg/kg/day with allowable increases to 0.2 mg/kg/day. A concurrent nonsteroidal anti-inflammatory drug was allowed. Twenty-one patients were enrolled in the study, and we obtained 2 or more serial samples on 13 of the children. At a constant dosage of 0.1 mg/kg/day, steady state blood gold concentrations were attained in 11 to 13 weeks of therapy and, in the absence of a dosage change, remained remarkably constant through extended periods. The blood gold concentration was related to total daily dosage rather than to the cumulative amount of gold received. Increasing or decreasing the dose resulted in a direct effect on concentration. The clinical value of blood gold levels resulting from auranofin therapy in JRA will have to be established through double-blind controlled trials.

  5. Synergistic extraction of gold from the refractory gold ore via ultrasound and chlorination-oxidation.

    Science.gov (United States)

    Fu, Likang; Zhang, Libo; Wang, Shixing; Cui, Wei; Peng, Jinhui

    2017-07-01

    A synergistic extraction method for gold from the refractory gold ores via ultrasound and chlorination-oxidation was developed. The effects of solid-liquid ratio, extraction time, ultrasound power, NaClO concentration and NaOH concentration on the extraction rate of gold from the refractory gold ore were investigated. The optimum conditions were as follows: NaClO concentration of 1.5mol/L, NaOH concentration of 1.5mol/L, solid-liquid ratio of 5, ultrasound power of 200W and ultrasound time of 2h. Under the optimal conditions, 68.55% of gold was extracted. However, only 45.8% of gold was extracted after 6h without the ultrasound-assisted extraction. XRD and SEM were used to analyze the influence of ultrasound on the mineral properties and strengthening mechanism. The results showed that the interface layer was peeled, new surface was exposed, reaction resistance was reduced, the liquid-solid reaction was promoted and reaction speed was greatly improved under ultrasound. According to the results of range and variance analysis, the optimum leaching experiment with orthogonal design was almost identical with the optimum experiment of single factor. Among them, the ultrasound power was the most significant factors affecting leaching rate of gold. Compared with other extraction method, the synergistic extraction process decomposed completely sulfide and improved significantly the extraction rate of gold. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Protracted elimination of gold nanoparticles from mouse liver

    DEFF Research Database (Denmark)

    Sadauskas, Evaldas; Wallin, Håkan; Stoltenberg, Meredin

    2009-01-01

    The present study aims at revealing the fate of 40-nm gold nanoparticles after intravenous injections. The gold nanoparticles were traced histochemically with light and transmission electron microscopy using autometallographic (AMG) staining, and the gold content in the liver was determined...... with inductively coupled plasma mass spectrometry (ICP-MS). Gold nanoparticles were identified in almost all Kupffer cells one day after the injection, but the fraction of gold-loaded cells gradually decreased to about one fifth after 6 months. Transmission electron microscopic analysis showed that the gold......% fall in the gold content over the observed 6 months, the AMG finding of a significant reduction in the stained area of the liver sections and number of macrophages loaded with gold nanoparticles reveals that over time an increasing part of the total amount of gold nanoparticles in the liver...

  7. An econometrics method for estimating gold coin futures prices

    Directory of Open Access Journals (Sweden)

    Fatemeh Pousti

    2011-10-01

    Full Text Available In this paper, we present some regression functions to estimate gold coin future price based on gold coin price, future exchange price, price of gold traded globally and trend of time. The proposed model of this paper is used for price estimation of special gold coin traded in Iran. The proposed model of this paper is applied for historical data of future gold prices and the results are discussed. The preliminary results indicate that an increase on gold coin price could increase gold coin future price. An increase on foreign exchange price has negative impact on gold coin future and present trend on time has positive impact on gold coin future.

  8. Beneficiation of the gold bearing ore by gravity and flotation

    Science.gov (United States)

    Gül, Alim; Kangal, Olgaç; Sirkeci, Ayhan A.; Önal, Güven

    2012-02-01

    Gold concentration usually consists of gravity separation, flotation, cyanidation, or the combination of these processes. The choice among these processes depends on the mineralogical characterization and gold content of the ore. Recently, the recovery of gold using gravity methods has gained attention because of low cost and environmentally friendly operations. In this study, gold pre-concentrates were produced by the stepwise gravity separation and flotation techniques. The Knelson concentrator and conventional flotation were employed for the recovery of gold. Gold bearing ore samples were taken from Gümüşhane Region, northern east part of Turkey. As a result of stepwise Knelson concentration experiments, a gold concentrate assaying around 620 g/t is produced with 41.4wt% recovery. On the other hand, a gold concentrate about 82 g/t is obtained with 89.9wt% recovery from a gold ore assaying 6 g/t Au by direct flotation.

  9. Silver, gold, and alloyed silver-gold nanoparticles: characterization and comparative cell-biologic action

    Science.gov (United States)

    Mahl, Dirk; Diendorf, Jörg; Ristig, Simon; Greulich, Christina; Li, Zi-An; Farle, Michael; Köller, Manfred; Epple, Matthias

    2012-10-01

    Silver, gold, and silver-gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly( N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15-25 nm), gold (5-6 nm), and silver-gold (50:50; 10-12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver-gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver-gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver-gold nanoparticles in the concentration range of 5-20 μg mL-1 induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

  10. Silver, gold, and alloyed silver-gold nanoparticles: characterization and comparative cell-biologic action

    Energy Technology Data Exchange (ETDEWEB)

    Mahl, Dirk; Diendorf, Joerg; Ristig, Simon [University of Duisburg-Essen, Department of Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Greulich, Christina [Ruhr-University of Bochum, Bergmannsheil University Hospital/Surgical Research (Germany); Li Zian; Farle, Michael [University of Duisburg-Essen, Faculty of Physics, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Koeller, Manfred [Ruhr-University of Bochum, Bergmannsheil University Hospital/Surgical Research (Germany); Epple, Matthias, E-mail: matthias.epple@uni-due.de [University of Duisburg-Essen, Department of Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany)

    2012-10-15

    Silver, gold, and silver-gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly(N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15-25 nm), gold (5-6 nm), and silver-gold (50:50; 10-12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver-gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver-gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver-gold nanoparticles in the concentration range of 5-20 {mu}g mL{sup -1} induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

  11. Au与Au合金的微合金化%Microalloying of Gold and Gold Alloys

    Institute of Scientific and Technical Information of China (English)

    宁远涛

    2008-01-01

    Microalloying to pure gold and gold alloys was discussed and summerized. The main effects of microalloying elements in gold alloys are those for strengthening, for regulating electrical resistance, for refining grain-size and for increasing recrystallization temperature. In nearly all applications, the elements with large difference of melting point or atomic size to gold, and those with low solid solubility in gold, such as alkali- and alkali-earth metals, rare earth metals, high melting point metals, metalloids and some simple metals are selected as microalloying elements. Some examples of microalloyed gold alloys are introduced. The effects of many microalloying elements on the properties of gold and gold alloys are often multiple-coincidence. Some selection principles of microalloying elements for gold and gold alloys with various applications are summarized.%讨论和总结了Au与Au合金的微合金化.在Au合金中,微合金化元素的主要作用是强化、调整电阻率、细化晶粒尺寸和提高再结晶温度等. 几乎在所有的应用中,相对于Au具有大的熔点差或原子尺寸差的合金元素,诸如碱和碱土金属、稀土金属、高熔点金属、类金属和某些简单金属被选择作为微合金化元素. 介绍了微合金化Au合金的某些应用.许多微合金化元素对Au和Au合金性能的影响常常是多重和协同的.总结了对于不同应用的Au和Au合金的微合金化元素的某些选择原则.

  12. Precipitation of lamellar gold nanocrystals in molten polymers

    Science.gov (United States)

    Palomba, M.; Carotenuto, G.

    2016-05-01

    Non-aggregated lamellar gold crystals with regular shape (triangles, squares, pentagons, etc.) have been produced by thermal decomposition of gold chloride (AuCl) molecules in molten amorphous polymers (polystyrene and poly(methyl methacrylate)). Such covalent inorganic gold salt is high soluble into non-polar polymers and it thermally decomposes at temperatures compatible with the polymer thermal stability, producing gold atoms and chlorine radicals. At the end of the gold precipitation process, the polymer matrix resulted chemically modified because of the partial cross-linking process due to the gold atom formation reaction.

  13. Application of gold in the field of heterogeneous catalysis

    CERN Document Server

    Luo, Siwei

    2014-01-01

    Gold has been long thought as an inert metal which finds most of its use in jewelry and monetary exchange. However, catalysis by gold has rapidly become a hot topic in chemistry ever since Haruta and Hutchings found gold to be an extraordinary good heterogeneous catalyst in certain reactions. Here in this paper, several model reactions which made gold historically famous as a catalyst and a currently hot topic will be demonstrated, such as oxidation of CO, selective oxidation, and hydrodechlorination. Conclusions on the chemical nature of gold will be made as well as future perspectives of designing gold as a better catalyst.

  14. Gold nanoparticle-based electrochemical biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Pingarron, Jose M.; Yanez-Sedeno, Paloma; Gonzalez-Cortes, Araceli [Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid (Spain)

    2008-08-01

    The unique properties of gold nanoparticles to provide a suitable microenvironment for biomolecules immobilization retaining their biological activity, and to facilitate electron transfer between the immobilized proteins and electrode surfaces, have led to an intensive use of this nanomaterial for the construction of electrochemical biosensors with enhanced analytical performance with respect to other biosensor designs. Recent advances in this field are reviewed in this article. The advantageous operational characteristics of the biosensing devices designed making use of gold nanoparticles are highlighted with respect to non-nanostructured biosensors and some illustrative examples are commented. Electrochemical enzyme biosensors including those using hybrid materials with carbon nanotubes and polymers, sol-gel matrices, and layer-by-layer architectures are considered. Moreover, electrochemical immunosensors in which gold nanoparticles play a crucial role in the electrode transduction enhancement of the affinity reaction as well as in the efficiency of immunoreagents immobilization in a stable mode are reviewed. Similarly, recent advances in the development of DNA biosensors using gold nanoparticles to improve DNA immobilization on electrode surfaces and as suitable labels to improve detection of hybridization events are considered. Finally, other biosensors designed with gold nanoparticles oriented to electrically contact redox enzymes to electrodes by a reconstitution process and to the study of direct electron transfer between redox proteins and electrode surfaces have also been treated. (author)

  15. Gold Nanoparticle Labels Amplify Ellipsometric Signals

    Science.gov (United States)

    Venkatasubbarao, Srivatsa

    2008-01-01

    The ellipsometric method reported in the immediately preceding article was developed in conjunction with a method of using gold nanoparticles as labels on biomolecules that one seeks to detect. The purpose of the labeling is to exploit the optical properties of the gold nanoparticles in order to amplify the measurable ellipsometric effects and thereby to enable ultrasensitive detection of the labeled biomolecules without need to develop more-complex ellipsometric instrumentation. The colorimetric, polarization, light-scattering, and other optical properties of nanoparticles depend on their sizes and shapes. In the present method, these size-and-shape-dependent properties are used to magnify the polarization of scattered light and the diattenuation and retardance of signals derived from ellipsometry. The size-and-shape-dependent optical properties of the nanoparticles make it possible to interrogate the nanoparticles by use of light of various wavelengths, as appropriate, to optimally detect particles of a specific type at high sensitivity. Hence, by incorporating gold nanoparticles bound to biomolecules as primary or secondary labels, the performance of ellipsometry as a means of detecting the biomolecules can be improved. The use of gold nanoparticles as labels in ellipsometry has been found to afford sensitivity that equals or exceeds the sensitivity achieved by use of fluorescence-based methods. Potential applications for ellipsometric detection of gold nanoparticle-labeled biomolecules include monitoring molecules of interest in biological samples, in-vitro diagnostics, process monitoring, general environmental monitoring, and detection of biohazards.

  16. Engineered Gold Nanoparticles and Plant Adaptation Potential

    Science.gov (United States)

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-09-01

    Use of metal nanoparticles in biological system has recently been recognised although little is known about their possible effects on plant growth and development. Nanoparticles accumulation, translocation, growth response and stress modulation in plant system is not well understood. Plants exposed to gold and gold nanoparticles have been demonstrated to exhibit both positive and negative effects. Their growth and yield vary from species to species. Cytoxicity of engineered gold nanoparticles depends on the concentration, particle size and shape. They exhibit increase in vegetative growth and yield of fruit/seed at lower concentration and decrease them at higher concentration. Studies have shown that the gold nanoparticles exposure has improved free radical scavenging potential and antioxidant enzymatic activities and alter micro RNAs expression that regulate different morphological, physiological and metabolic processes in plants. These modulations lead to improved plant growth and yields. Prior to the use of gold nanoparticles, it has been suggested that its cost may be calculated to see if it is economically feasible.

  17. Amplitude enhancement by a gold dimer

    Science.gov (United States)

    Hong, Xin; Wang, Jingxin; Jin, Zheng

    2016-10-01

    The unique optical properties such as brightness, non-bleaching, good bio-compatibility make gold particles ideal label candidates for molecular probes. Due to the strongly enhanced field, aggregation of gold nanoparticles finds themselves plenty of applications in bio-imaging. But limited by its small cross-section associated with nanometer sized particle, it is a big challenge to employ it in a single molecular detection. The field enhancement results from the effect of plasmonic coupling between two closely attached gold nanoparticle under the right excitation condition. With the aim to apply the gold dimer probe to find the molecules in our recently established optical detection method, we compared of the amplitude enhancement by the dimer relative to a single particle. The amplitude distribution under a highly focused illumination objective was calculated, whose results suggest that at the optimized excitation condition, the local field can be enhanced 190 fold. In consequence, experimental detection was carried out. Gold dimers were linked together by the hybridization of two single chain DNAs. Dimer and single particle probes were mixed together in one detection. Overwhelming contrast between these two kinds of probes were clearly exhibited in the experimental detection image. This method can provide a way to a high specific detection in early diagnosis.

  18. Simple fabrication of gold nanobelts and patterns.

    Directory of Open Access Journals (Sweden)

    Renyun Zhang

    Full Text Available Gold nanobelts are of interest in several areas; however, there are only few methods available to produce these belts. We report here on a simple evaporation induced self-assembly (EISA method to produce porous gold nanobelts with dimensions that scale across nanometer (thickness ∼80 nm and micrometer (width ∼20 µm, to decimeter (length ∼0.15 m. The gold nanobelts are well packed on the beaker wall and can be easily made to float on the surface of the solution for depositing onto other substrates. Microscopy showed that gold nanobelts had a different structure on the two sides of the belt; the density of gold nanowires on one side was greater than on the other side. Electrical measurements showed that these nanobelts were sensitive to compressive or tensile forces, indicating a potential use as a strain sensor. The patterned nanobelts were further used as a template to grow ZnO nanowires for potential use in applications such as piezo-electronics.

  19. COMMODITY SCALE SYNTHESIS OF 1-METHYLIMIDAZOLE BASED IONIC LIQUIDS USING A SPINNING TUBE-IN-TUBE REACTOR

    Science.gov (United States)

    The continuous large-scale preparation of several 1-methylimidazole based ionic liquids was carried out using a Spinning Tube-in-Tube (STT) reactor (manufactured by Kreido Laboratories). This reactor, which embodies and facilitates the use of Green Chemistry principles and Proce...

  20. COMMODITY SCALE SYNTHESIS OF 1-METHYLIMIDAZOLE BASED IONIC LIQUIDS USING A SPINNING TUBE-IN-TUBE REACTOR

    Science.gov (United States)

    The continuous large-scale preparation of several 1-methylimidazole based ionic liquids was carried out using a Spinning Tube-in-Tube (STT) reactor (manufactured by Kreido Laboratories). This reactor, which embodies and facilitates the use of Green Chemistry principles and Proce...

  1. TB incidence in an adolescent cohort in South Africa.

    Directory of Open Access Journals (Sweden)

    Hassan Mahomed

    Full Text Available BACKGROUND: Tuberculosis (TB is a major public health problem globally. Little is known about TB incidence in adolescents who are a proposed target group for new TB vaccines. We conducted a study to determine the TB incidence rates and risk factors for TB disease in a cohort of school-going adolescents in a high TB burden area in South Africa. METHODS: We recruited adolescents aged 12 to 18 years from high schools in Worcester, South Africa. Demographic and clinical information was collected, a tuberculin skin test (TST performed and blood drawn for a QuantiFERON TB Gold assay at baseline. Screening for TB cases occurred at follow up visits and by surveillance of registers at public sector TB clinics over a period of up to 3.8 years after enrolment. RESULTS: A total of 6,363 adolescents were enrolled (58% of the school population targeted. During follow up, 67 cases of bacteriologically confirmed TB were detected giving an overall incidence rate of 0.45 per 100 person years (95% confidence interval 0.29-0.72. Black or mixed race, maternal education of primary school or less or unknown, a positive baseline QuantiFERON assay and a positive baseline TST were significant predictors of TB disease on adjusted analysis. CONCLUSION: The adolescent TB incidence found in a high burden setting will help TB vaccine developers plan clinical trials in this population. Latent TB infection and low socio-economic status were predictors of TB disease.

  2. Real time polymerase chain reaction (rt-pcr for mycobacterium tuberculosis in serpiginous choroiditis- A study of 29 cases

    Directory of Open Access Journals (Sweden)

    RadhaAnnamalai, Jyotirmay Biswas, Sudharshan S, Gayathri R, Lily Therese, Viswanathan S, NamithaBhuvaneswari

    2014-07-01

    Full Text Available Purpose: A study of real time Polymerase Chain Reaction for Mycobacterium tuberculosis (M. tuberculosis DNA in 29 cases of active serpiginous choroiditis. Design: Case control study. Methods: DNA extraction from the aqueous humor was carried out using QIAMP DNA extraction kit. Real- time Polymerase Chain reaction (RT-PCR for MTB was carried out using Genosen’s Mtb complex quantitative Real time PCR kit. All patients were also subjected to complete blood count, venereal disease research laboratory test, chest radiograph, QuantiFERON TB Gold test on the blood and polymerase chain reaction on a sample of aqueous humor. Results: Aqueous aspirate showed copies of mycobacterium tuberculosis DNA in one out of twenty nine cases of serpiginous choroiditis. Direct smear and culture for mycobacteria was negative in all cases. Conclusion: RT-PCR identifies MTB DNA in suspected latent tuberculosis in serpiginous choroiditis with high specificity. Serpiginous choroiditis and multifocal choroiditis due to tuberculosis may resemble each other clinically but have distinct clinical features which can be confirmed by real time polymerase chain reaction performed on the aqueous humor The association between serpiginous choroiditis and tuberculosis would be a chance association or if present a rare association.

  3. Clinical and bacteriological correlates of whole blood interferon gamma (IFN-γ) in newly detected cases of pulmonary TB

    Institute of Scientific and Technical Information of China (English)

    Bandyopadhyay M; Bhakta A; Chakrabarty S; Pal M; Bharati P

    2010-01-01

    Objective:To determine the relationship of the capacity to produce interferon gamma (IFN-毭) in whole blood, bacteriological, hematological, radiographic and clinical presentations in new,HIVseronegative cases of pulmonary tuberculosis (TB).Methods: 80 cases and 50 control subjects aged 15 years onwards, representative of Kasturba Hospital and Nursing schools of Wardha district of Maharashtra state in India were examined for their health condition with standard methodology.Results: Among theseTB patients, 73.8% were Quantiferon-TB gold (QFT) positive withIFN-γ concentration as 0.35 IU or more and there was none in healthy controls. The meanIFN-γ concentrations varied between 9.58IU (50-59 yrs) and 2.58IU ≥60 yrs), showing no trend. The differences in positivity and meanIFN-γconcentrations were statistically insignificant. Both the QFT positivity andIFN-γconcentrations were higher in normal lymphocyte percent as compared to below and above normal, but differences were not statistically significant.Conclusions: TheIFN-γconcentrations are not correlated with any of the predictors of disease severity studied, the levels are significantly higher in observation group as compared to healthy group.

  4. Flow chemistry: intelligent processing of gas-liquid transformations using a tube-in-tube reactor.

    Science.gov (United States)

    Brzozowski, Martin; O'Brien, Matthew; Ley, Steven V; Polyzos, Anastasios

    2015-02-17

    reactive gas in a given reaction mixture. We have developed a tube-in-tube reactor device consisting of a pair of concentric capillaries in which pressurized gas permeates through an inner Teflon AF-2400 tube and reacts with dissolved substrate within a liquid phase that flows within a second gas impermeable tube. This Account examines our efforts toward the development of a simple, unified methodology for the processing of gaseous reagents in flow by way of development of a tube-in-tube reactor device and applications to key C-C, C-N, and C-O bond forming and hydrogenation reactions. We further describe the application to multistep reactions using solid-supported reagents and extend the technology to processes utilizing multiple gas reagents. A key feature of our work is the development of computer-aided imaging techniques to allow automated in-line monitoring of gas concentration and stoichiometry in real time. We anticipate that this Account will illustrate the convenience and benefits of membrane tube-in-tube reactor technology to improve and concomitantly broaden the scope of gas/liquid/solid reactions in organic synthesis.

  5. Gold nanocrystals with DNA-directed morphologies

    Science.gov (United States)

    Ma, Xingyi; Huh, June; Park, Wounjhang; Lee, Luke P.; Kwon, Young Jik; Sim, Sang Jun

    2016-09-01

    Precise control over the structure of metal nanomaterials is important for developing advanced nanobiotechnology. Assembly methods of nanoparticles into structured blocks have been widely demonstrated recently. However, synthesis of nanocrystals with controlled, three-dimensional structures remains challenging. Here we show a directed crystallization of gold by a single DNA molecular regulator in a sequence-independent manner and its applications in three-dimensional topological controls of crystalline nanostructures. We anchor DNA onto gold nanoseed with various alignments to form gold nanocrystals with defined topologies. Some topologies are asymmetric including pushpin-, star- and biconcave disk-like structures, as well as more complex jellyfish- and flower-like structures. The approach of employing DNA enables the solution-based synthesis of nanocrystals with controlled, three-dimensional structures in a desired direction, and expands the current tools available for designing and synthesizing feature-rich nanomaterials for future translational biotechnology.

  6. Gold(III) complexes in medicinal chemistry.

    Science.gov (United States)

    Maia, Pedro Ivo da Silva; Deflon, Victor M; Abram, Ulrich

    2014-09-01

    A number of gold(III) compounds has been designed with the objective of overcoming the disadvantages associated with the platinum-based drugs for cancer treatment. Compounds of a remarkable structural manifold show significant antiproliferative effects in vitro against a number of cancer cells, including cisplatin resistant ones. The target of most of them is, unlike that of cisplatin, not the DNA. Although the mechanisms of action displayed by the gold compounds in biological media are still under investigation, many studies show evidence that the cellular targets are mitochondria-based. Recent advances in gold(III) medicinal chemistry also recommend such compounds for other pharmacological applications such as the treatment of viral or parasitic diseases. The radioactive isotopes (198)Au and (199)Au present potential in radiotherapy.

  7. Galvanic gold plating for fixed dental prosthesis.

    Science.gov (United States)

    Ozcelik, Tuncer Burak; Yilmaz, Burak

    2013-07-01

    Metal ceramic partial fixed dental prostheses have been commonly used for the replacement of missing teeth for many years. Because of an increase in the price of gold, base metal alloys have been the choice of alloy for the fabrication of metal ceramic restorations in many dental clinics. Some major disadvantages of base metals are their corrosion and the dark coloration they may cause at the crown margins. This article describes a galvanic gold-plating technique, which is used to minimize corrosion and improve the esthetics of metal ceramic restorations fabricated with Cr-Co base metal alloys. This technique involves the deposition of a 6 μm to 8 μm 24 K gold layer directly onto the Cr-Co cast prosthesis framework. The technique improves metal surface properties, making them more biocompatible and usable, however, requires additional equipment and experienced laboratory technicians. Clinical studies should be performed to corroborate the long term success of this technique.

  8. Hybrid gold single crystals incorporating amino acids

    CERN Document Server

    Chen, Linfeng; Weber, Eva; Fitch, Andy N; Pokroy, Boaz

    2016-01-01

    Composite hybrid gold crystals are of profound interest in various research areas ranging from materials science to biology. Their importance is due to their unique properties and potential implementation, for example in sensing or in bio-nanomedicine. Here we report on the formation of hybrid organic-metal composites via the incorporation of selected amino acids histidine, aspartic acid, serine, glutamine, alanine, cysteine, and selenocystine into the crystal lattice of single crystals of gold. We used electron microscopy, chemical analysis and high-resolution synchrotron powder X ray diffraction to examine these composites. Crystal shape, as well as atomic concentrations of occluded amino acids and their impact on the crystal structure of gold, were determined. Concentration of the incorporated amino acid was highest for cysteine, followed by serine and aspartic acid. Our results indicate that the incorporation process probably occurs through a complex interaction of their individual functional groups with ...

  9. Ultrasonic-aided fabrication of gold nanofluids.

    Science.gov (United States)

    Chen, Hui-Jiuan; Wen, Dongsheng

    2011-03-07

    A novel ultrasonic-aided one-step method for the fabrication of gold nanofluids is proposed in this study. Both spherical- and plate-shaped gold nanoparticles (GNPs) in the size range of 10-300 nm are synthesized. Subsequent purification produces well-controlled nanofluids with known solid and liquid contents. The morphology and properties of the nanoparticle and nanofluids are characterized by transmission electron microscopy, scanning electron microscope, energy dispersive X-ray spectroscope, X-ray diffraction spectroscopy, and dynamic light scattering, as well as effective thermal conductivities. The ultrasonication technique is found to be a very powerful tool in engineering the size and shape of GNPs. Subsequent property measurement shows that both particle size and particle shape play significant roles in determining the effective thermal conductivity. A large increase in effective thermal conductivity can be achieved (approximately 65%) for gold nanofluids using plate-shaped particles under low particle concentrations (i.e.764 μM/L).

  10. Layering-induced Superlubricity: Gold on Graphite

    Science.gov (United States)

    Vanossi, Andrea; Guerra, Roberto; Tosatti, Erio; Nanofriction Group Sissa Team

    2015-03-01

    By means of realistic MD simulations, we explore the static friction trend as a function of the true contact area and the model dimensionality for 2D gold nanoislands and 3D gold nanoclusters deposited on graphite, interesting tribological systems whose slow and fast dynamics have been previously investigated. For increasing island size, because of the relative gold-graphite lattice mismatch, the interface stress energy has the chance to pile up by forming frustrated unmatched (i.e., incommensurate) regions and to develop a continuous solitonic pathway, foreshadowing a possible condition for the occurrence of ultra-low friction regimes. The significant reduction of the depinning threshold, towards superlubricity, with the system dimensionality can be ascribed to a layering-induced effective stiffness of the interface contact, favoring the natural Au-C lattice incommensurability. Partly sponsored under SNSF Sinergia Grant CRSII2 136287/1, EU ERC Grant No. 320796 MODPHYSFRICT, EU COST Action MP1303.

  11. Regional and subcellular distribution of gold in brain of gold thioglucose obese mouse.

    Science.gov (United States)

    Kataoka, K; Danbara, H; Sunayashiki, K; Okuno, S; Sorimachi, M; Tanaka, M; Chikamori, K

    1978-01-01

    By employing neutron activation analysis, endogenous content of gold was estimated quantitatively in discrete brain areas and in subcellular fractions of the hypothalamus of gold thioglucose (GTG) induced obese mice. The highest concentration of gold was obtained in the ventromedial hypothalamus (VMH) reaching approximately 100 ng/mg wet tissue. Significantly higher concentrations were observed in other hypothalamic subareas followed by certain limbic areas and the thalamus, while in the cerebral and the cerebellar cortex the gold concentration was very low. Subcellularly, the hypothalamic gold was principally recovered in the supernatant fraction particularly after a hyposmotic shock treatment of the crude mitochondrial fraction. Contrary to GTG, treatment with gold thiomalate (GTM) did not induce obesity in the mouse, although considerable amount of gold was observed in the VMH, a finding suggesting the existence in the VMH of at least a two step mechanisms for inducing GTG obesity. To identify the satiety neuron transmitter, an analysis of certain enzyme activities involved in the synthesis of known transmitters, such as acetylcholine or gamma-aminobutyric acid (GABA), was made in the GTG-obese mice. There were no significant changes in any of the areas functionally related to the VMH.

  12. Direct formation of gold nanorods on surfaces using polymer-immobilised gold seeds.

    Science.gov (United States)

    Abyaneh, Majid K; Parisse, Pietro; Casalis, Loredana

    2016-01-01

    Herein, we present the formation of gold nanorods (GNRs) on novel gold-poly(methyl methacrylate) (Au-PMMA) nanocomposite substrates with unprecedented growth control through the polymer molecular weight (M w) and gold-salt-to-polymer weight ratio. For the first time, GNRs have been produced by seed-mediated direct growth on surfaces that were pre-coated with polymer-immobilised gold seeds. A Au-PMMA nanocomposite formed by UV photoreduction has been used as the gold seed. The influence of polymer M w and gold concentration on the formation of GNRs has been investigated and discussed. The polymer nanocomposite formed with a lower M w PMMA and 20 wt % gold salt provides a suitable medium for growing well-dispersed GNRs. In this sample, the average dimension of produced GNRs is 200 nm in length with aspect ratios up to 10 and a distribution of GNRs to nanoparticles of nearly 22%. Suitable characterization techniques such as AFM and SEM have been used to support concept of the proposed growth method.

  13. Major Brazilian gold deposits - 1982 to 1999

    Science.gov (United States)

    Thorman, Charles H.; DeWitt, Ed; Maron, Marcos A.; Ladeira, Eduardo A.

    2001-07-01

    Brazil has been a major but intermittent producer of gold since its discovery in 1500. Brazil led the world in gold production during the 18th and early 19th centuries. From the late 19th century to the late 20th century, total mining company and garimpeiro production was small and relatively constant at about 5 to 8 t/year. The discovery of alluvial deposits in the Amazon by garimpeiros in the 1970s and the opening of eight mines by mining companies from 1983 to 1990 fueled a major boom in Brazil's gold production, exceeding 100 t/year in 1988 and 1989. However, garimpeiro alluvial production decreased rapidly in the 1990s, to about 10 t/year by 1999. Company production increased about tenfold from about 4 t/year in 1982 to 40 t in 1992. Production from 1992 to the present remained relatively stable, even though several mines were closed or were in the process of closing and no new major mines were put into production during that period. Based on their production history from 1982-1999, 17 gold mines are ranked as major (>20 t) and minor (3-8 t) mines. From 1982-1999, deposits hosted in Archean rocks produced 66% of the gold in Brazil, whereas deposits in Paleoproterozoic and Neoproterozoic rocks accounted for 19% and 15%, respectively. Deposits in metamorphosed sedimentary rocks, especially carbonate-rich rocks and carbonate iron-formation, yielded the great bulk of the gold. Deposits in igneous rocks were of much less importance. The Archean and Paleoproterozoic terranes of Brazil largely lack base-metal-rich volcanogenic massive sulfide deposits, porphyry deposits, and polymetallic veins and sedimentary exhalative deposits. An exception to this is in the Carajás Mineral Province.

  14. Gold and Silver Inlaid Bronze Sheep

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Gold and silver inlaying is a metal processing technique popular during the Spring and Autumn Period (770-476 B. C.) and the Warring States Period (475-221 B. C.). Patterns on the surface of the bronze figure are chiselled out and gold and silver threads (which can be as thin as hair) are inlaid. Finally the whole figure is filed and polished resulting in a splendid artistic work highlighting the different colours of the three different kinds of metal. The artifact shown here was unearthed from Ningxia'...

  15. Current methods for synthesis of gold nanoparticles.

    Science.gov (United States)

    Herizchi, Roya; Abbasi, Elham; Milani, Morteza; Akbarzadeh, Abolfazl

    2016-01-01

    Metal nanoparticles, such as nanoparticles synthesized using gold, have numerous uncommon chemical and physical properties due to the effects of their quantum size and their large surface area, in comparison with other metal atoms or bulk metal. Gold nanoparticles (GNPs), in particular, are very attractive because of their size and shape-dependent properties. Metal nanoparticles have gathered extensive attention due to their uncommon properties and promising applications in photonics, electronics, biochemical sensing, and imaging. This review covers recent advances in the synthesis of GNPs.

  16. Radiation Heat Waves in Gold Plasma

    Institute of Scientific and Technical Information of China (English)

    YANG Jia-Min; XU Yan; DING Yao-Nan; LAI Dong-Xian; DING Yong-Kun; JIANG Shao-En; ZHENG Zhi-Jian; MIAO Wen-Yong

    2003-01-01

    Eight beams 0.35/um laser with pulse duration of about 1.0ns and energy of 260 J per beam was injected into a cylindrical cavity to generate intense x-ray radiation on the "Shengguang I" high power laser facility. Gold foils with a thickness in the range of 0.09-0.52/j,m were attached on the diagnostic hole of the cavity and ablated by the intense x-ray radiation. The propagating radiation heat wave in the high-Z gold plasma was observed clearly. For comparison, we also simulated the experimental results.

  17. Functionalized Gold Nanoparticles and Their Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Shree R. Singh

    2011-06-01

    Full Text Available Metal nanoparticles are being extensively used in various biomedical applications due to their small size to volume ratio and extensive thermal stability. Gold nanoparticles (GNPs are an obvious choice due to their amenability of synthesis and functionalization, less toxicity and ease of detection. The present review focuses on various methods of functionalization of GNPs and their applications in biomedical research. Functionalization facilitates targeted delivery of these nanoparticles to various cell types, bioimaging, gene delivery, drug delivery and other therapeutic and diagnostic applications. This review is an amalgamation of recent advances in the field of functionalization of gold nanoparticles and their potential applications in the field of medicine and biology.

  18. Chirality in Bare and Passivated Gold Nanoclusters

    CERN Document Server

    Garzon, I L; Rodrigues-Hernandez, J I; Sigal, I; Beltran, M R; Michaelian, K

    2002-01-01

    Chiral structures have been found as the lowest-energy isomers of bare (Au$_{28}$ and Au$_{55}) and thiol-passivated (Au$_{28}(SCH$_{3})$_{16}$ and Au$_{38}$(SCH$_{3}$)$_{24}) gold nanoclusters. The degree of chirality existing in the chiral clusters was calculated using the Hausdorff chirality measure. We found that the index of chirality is higher in the passivated clusters and decreases with the cluster size. These results are consistent with the observed chiroptical activity recently reported for glutahione-passivated gold nanoclusters, and provide theoretical support for the existence of chirality in these novel compounds.

  19. Nanoporous Gold: Fabrication, Characterization, and Applications

    Directory of Open Access Journals (Sweden)

    Michael L. Reed

    2009-12-01

    Full Text Available Nanoporous gold (np-Au has intriguing material properties that offer potential benefits for many applications due to its high specific surface area, well-characterized thiol-gold surface chemistry, high electrical conductivity, and reduced stiffness. The research on np-Au has taken place on various fronts, including advanced microfabrication and characterization techniques to probe unusual nanoscale properties and applications spanning from fuel cells to electrochemical sensors. Here, we provide a review of the recent advances in np-Au research, with special emphasis on microfabrication and characterization techniques. We conclude the paper with a brief outline of challenges to overcome in the study of nanoporous metals.

  20. Anisotropic Gold Nanocrystals:. Synthesis and Characterization

    Science.gov (United States)

    Stiufiuc, R.; Toderas, F.; Iosin, M.; Stiufiuc, G.

    In this letter we report on successful preparation and characterization of anisotropic gold nanocrystals bio-synthesized by reduction of aqueous chloroaurate ions in pelargonium plant extract. The nanocrystals have been characterized by means of Transmission Electron Microscopy (TEM), UV-VIS absorption spectroscopy and tapping mode atomic force microscopy (TM-AFM). Using these investigation techniques, the successful formation of anisotropic single nanocrystals with the preferential growth direction along the gold (111) plane has been confirmed. The high detail phase images could give us an explanation concerning the growth mechanism of the nanocrystals.

  1. Ligations of Gold Atoms with Iron Porphyrin

    DEFF Research Database (Denmark)

    Zhang, Ling; Kepp, Kasper Planeta; Ulstrup, Jens

    Gold is an exotic material with d-electrons deciding electronic mappings andconfigurations of adsorbed molecules. The specific interaction of Au atoms and S-, Ncappedmolecules make gold nanoparticles widely applied in the medicine transport andimmunoassay. Density functional theory demonstrates...... that the electronic structure ofAu adatoms is d9s1but not d10s0 in the forms of Au-thiolates. The surrounding Ausurface atoms are passivated leading to both Au-Au and S-S interactions. A wide range of surface phenomena of nanoparticle size-control and break-junctions in surface physics and chemistry including...

  2. Wages in California During the Gold Rush

    OpenAIRE

    Margo, Robert A.

    1997-01-01

    The California Gold Rush was an unexpected shock of tremendous size that prompted the costly re-allocation of labor to a frontier region. Using newly-collected archival data, this paper presents estimates of nominal and real wages in Gold Rush California. Consistent with a simple dynamic model of labor market adjustment, real wages rose sharply during the early years of the Rush (1848-1852), declined abruptly following massive in-migration 1850s. However, although the Rush itself was a transi...

  3. Quantum Chemistry Calculations on the Interaction Between Kaolinite and Gold

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The density function and discrete variation method (DFT-DVM) is used to study the interaction between kaolinite and gold. The correlation among the structure, chemical bond and stability is discussed. Several models are selected without gold and with gold in different directions and sites. The results show that the models with gold on the edge of kaolinite basal layer are more stable than those with gold above or under the layer, the models with gold near to [AlO2(OH)4] octahedra are more stable than those with gold near to the vacancy without aluminium. The interaction between gold and the surface ions of kaolinite is strong enough to form the surface complexes.

  4. Effects of Quebracho Tannin on Recovery of Colloidal Gold from ...

    African Journals Online (AJOL)

    Michael

    2015-06-01

    Jun 1, 2015 ... Gold from Bioleached Wash Liquor”, Ghana Mining Journal, Vol. 15, No ... paper considered effects of Quebracho Tannin (QT) on recovery of gold from the oxidized flotation .... partial precipitation of iron which can help reduce.

  5. Rheumatoid arthritis, gold therapy, contact allergy and blood cytokines

    Science.gov (United States)

    Svensson, Åke; Möller, Halvor; Björkner, Bert; Bruze, Magnus; Leden, Ido; Theander, Jan; Ohlsson, Kjell; Linder, Carina

    2002-01-01

    Objective To study the clinical and biochemical effects of a low starting dose for gold therapy in rheumatoid arthritis patients with a contact allergy to gold. Methods Serum cytokines were assayed before and 24 h after the first injection of gold sodium thiomalate (GSTM). Results Contact allergy to gold was found in 4 of 19 patients. Compared to gold-negative patients (starting dose: 10 mg GSTM), there was a larger increase in serum TNFalpha (p < 0.05), sTNF-R1 (NS), and IL-1 ra (p < 0.05) in gold-allergic patients. Conclusions Cytokines are released in blood by GSTM in RA patients with gold allergy. To minimize the risk of acute adverse reactions the starting dose of GSTM should be lowered to 5 mg. Alternatively, patients should be patch-tested before gold therapy; in test-positive cases, 5 mg is recommended as the first dose. PMID:11860615

  6. Effectiveness of the Primextra Gold in controlling weeds of ...

    African Journals Online (AJOL)

    Effectiveness of the Primextra Gold in controlling weeds of Cucumber ( Cucumis Sativus L. ) ... Journal of Applied Sciences and Environmental Management ... The efficacy of Primextra Gold herbicide in controlling weeds in cucumber was ...

  7. Shape-controlled Synthesis of Gold Nanoparticles from Gold(III)-chelates of β-diketones

    Science.gov (United States)

    Kundu, Subrata; Pal, Anjali; Ghosh, Sujit Kumar; Nath, Sudip; Panigrahi, Sudipa; Praharaj, Snigdhamayee; Basu, Soumen; Pal, Tarasankar

    2005-12-01

    Chelating ligands with β-diketone skeleton have been employed for the first time as reductant to produce ligand stabilized gold nanoparticles of different shapes out of aqueous HAuCl4 solutions. Evolution of stable gold nanoparticles happens to be first order with respect to gold particles having rate constants ˜ ˜10-2 min-1 and subsequent chlorine insertion in the β-diketone skeleton is reported as a general feature. Spherical or triangular or hexagonal particle evolution goes selectively under the influence of different β-diketones in terms of capping and reducing capabilities of the reductants.

  8. Shape-controlled Synthesis of Gold Nanoparticles from Gold(III)-chelates of {beta}-diketones

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Subrata [Indian Institute of Technology, Department of Chemistry (India); Pal, Anjali [Indian Institute of Technology, Department of Civil Engineering (India); Ghosh, Sujit Kumar; Nath, Sudip; Panigrahi, Sudipa; Praharaj, Snigdhamayee; Basu, Soumen; Pal, Tarasankar [Indian Institute of Technology, Department of Chemistry (India)], E-mail: tpal@chem.iitkgp.ernet.in

    2005-12-15

    Chelating ligands with {beta}-diketone skeleton have been employed for the first time as reductant to produce ligand stabilized gold nanoparticles of different shapes out of aqueous HAuCl{sub 4} solutions. Evolution of stable gold nanoparticles happens to be first order with respect to gold particles having rate constants {approx}{approx}10{sup -2} min{sup -1} and subsequent chlorine insertion in the {beta}-diketone skeleton is reported as a general feature. Spherical or triangular or hexagonal particle evolution goes selectively under the influence of different {beta}-diketones in terms of capping and reducing capabilities of the reductants.

  9. Antibacterial Activity and Cytotoxicity of Gold (I) and (III) Ions and Gold Nanoparticles

    OpenAIRE

    Shareena Dasari, TP; Zhang, Y; Yu, H.

    2015-01-01

    Gold nanoparticles (AuNPs) and gold ion complexes have been investigated for their antibacterial activities. However, the majority of the reports failed to disclose the concentration of free Au(I) or Au(III) present in solutions of AuNPs or gold ion complexes. The inconsistency of antibacterial activity of AuNPs may be due to the effect of the presence of Au(III). Here we report the antibacterial activity of Au(I) and Au(III) to four different bacteria: one nonpathogenic bacterium: E. coli an...

  10. Powder-in-tube (PIT) $Nb_{3}Sn$ conductors for high-field magnets

    CERN Document Server

    Lindenhovius, J L H; den Ouden, A; Wessel, W A J; ten Kate, H H J

    2000-01-01

    New Nb/sub 3/Sn conductors, based on the powder-in-tube (PIT) process, have been developed for application in accelerator magnets and high-field solenoids. For application in accelerator magnets, SMI has developed a binary 504 filament PIT conductor by optimizing the manufacturing process and adjustment of the conductor lay-out. It uniquely combines a non-copper current density of 2680 A/mm/sup 2/@10 T with an effective filament diameter of about 20 mu m. This binary conductor may be used in a 10 T, wide bore model separator dipole magnet for the LHC, which is being developed by a collaboration of the University of Twente and CERN. A ternary (Nb/7.5wt%Ta)/sub 3/Sn conductor containing 37 filaments is particularly suited for application in extremely high-field superconducting solenoids. This wire features a copper content of 43%, a non-copper current density of 217 A/mm/sup 2/@20 T and a B/sub c2/ of 25.6 T. The main issues and the experimental results of the development program of PIT Nb/sub 3/Sn conductors a...

  11. Loading and Contact Stress Analysis on the Thread Teeth in Tubing and Casing Premium Threaded Connection

    Directory of Open Access Journals (Sweden)

    Honglin Xu

    2014-01-01

    Full Text Available Loading and contact stress distribution on the thread teeth in tubing and casing premium threaded connections are of great importance for design optimization, pretightening force control, and thread failure prevention. This paper proposes an analytical method based on the elastic mechanics. This is quite different from other papers, which mainly rely on finite element analysis. The differential equation of load distribution on the thread teeth was established according to equal pitch of the engaged thread after deformation and solved by finite difference method. Furthermore, the relation between load acting on each engaged thread and mean contact stress on its load flank is set up based on the geometric description of thread surface. By comparison, this new analytical method with the finite element analysis for a modified API 177.8 mm premium threaded connection is approved. Comparison of the contact stress on the last engaged thread between analytical model and FEM shows that the accuracy of analytical model will decline with the increase of pretightening force after the material enters into plastic deformation. However, the analytical method can meet the needs of engineering to some extent because its relative error is about 6.2%~18.1% for the in-service level of pretightening force.

  12. On the look-up tables for the critical heat flux in tubes (history and problems)

    Energy Technology Data Exchange (ETDEWEB)

    Kirillov, P.L.; Smogalev, I.P. [Institute of Physics and Power Engineering, Kaluga (Russian Federation)

    1995-09-01

    The complication of critical heat flux (CHF) problem for boiling in channels is caused by the large number of variable factors and the variety of two-phase flows. The existence of several hundreds of correlations for the prediction of CHF demonstrates the unsatisfactory state of this problem. The phenomenological CHF models can provide only the qualitative predictions of CHF primarily in annular-dispersed flow. The CHF look-up tables covered the results of numerous experiments received more recognition in the last 15 years. These tables are based on the statistical averaging of CHF values for each range of pressure, mass flux and quality. The CHF values for regions, where no experimental data is available, are obtained by extrapolation. The correction of these tables to account for the diameter effect is a complicated problem. There are ranges of conditions where the simple correlations cannot produce the reliable results. Therefore, diameter effect on CHF needs additional study. The modification of look-up table data for CHF in tubes to predict CHF in rod bundles must include a method which to take into account the nonuniformity of quality in a rod bundle cross section.

  13. Headspace in-tube microextraction coupled with micellar electrokinetic chromatography of neutral aromatic compounds.

    Science.gov (United States)

    Cho, Sung Min; Park, Bum Su; Jung, Woo Sung; Lee, Sang Won; Jung, Yunhwan; Chung, Doo Soo

    2016-02-01

    Headspace (HS) extraction can be carried out easily and aptly via single drop microextraction coupled with capillary electrophoresis (CE). However, one drawback is the difficulty of keeping the single drop stably at the capillary tip. To solve this problem, we have recently demonstrated HS in-tube microextraction (ITME) of acidic compounds such as chlrophenols in an acidic sample using a basic run buffer plug in the separation capillary for CE as an acceptor phase. In this report, an organic acceptor plug in a capillary was used to extract neutral organic volatile pollutants such as BTEX (benzene, toluene, ethylbenzene, and m-xylene). After extraction, the analytes enriched in the organic acceptor plug were analyzed with micellar electrokinetic chromatography (MEKC). The enrichment factors for BTEX in a standard solution were up to 350 under an optimal condition of 25°C for 20 min. As an application, BTEX spiked into bottled water were analyzed with HS-ITME-MEKC, and the enrichment factors for BTEX were up to 320. The limits of detections were 1-4 ppb, which are at least 200 times lower than the US Environmental Protection Agency guidelines for drinking water, except benzene. The entire procedure of HS-ITME-MEKC was carried out automatically using a commercial CE instrument.

  14. Strategies to protect ram accelerator projectiles from in-tube gasdynamic heating

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanoff, D.W. [Eloret, Sunnyvale, CA (United States)

    2000-11-01

    A serious problem in advancing ram accelerator technology is the very high in-tube heat transfer rate to the projectile. Herein, we examine a number of strategies for protecting the projectile from gasdynamic heating. Radiation cooling of the projectile and flying the projectile through alternating regions of fuel-oxidizer-diluent drive gas and pure hydrogen are found to be totally unworkable. The ablative cooling technique has serious problems with a substantial retreat of the projectile surface. A transpiration cooling technique using liquid ammonia is calculated to provide adequate protection of the projectile for ram accelerator missions from 3 to 7 or 8 km/sec. Techniques for flying the projectile in pure hydrogen are also examined. One may have a vortex arrangement with a pure hydrogen core surrounded by a fuel-oxidizer-diluent mixture. The projectile may also fly in pure hydrogen while the driving energy is supplied by a deflagrating or detonating solid coating on the tube wall or by electrical energy input. The techniques for flying the projectile in pure hydrogen are judged to be extremely complex and expensive to implement. The transpiration technique appears to be the most viable way to protect projectiles flying in the 4 - 7 km/sec range. (orig.)

  15. Wrinkling behavior in tube hydroforming coupled with internal and external pressure

    Directory of Open Access Journals (Sweden)

    Cui X.L.

    2015-01-01

    Full Text Available Control and use of wrinkles is a challenge in tube hydroforming because wrinkle was always considered as one of the defects of tubes from the traditional view. In this paper, a dedicated experimental setup was designed and manufactured, using which the investigation of wrinkling behavior coupled with internal and external pressure can be realized. The effect of internal or external pressure on 5A02 aluminum alloy tubes and 0Cr18Ni9 stainless steel tubes were all investigated using this setup. It was found that the number and shape of wrinkles are strongly dependent on the internal or external pressure. More important is that the geometrical configuration of wrinkles can be perfectly characterized using the Gauss function rather than the sine function adopted in the published literature. In addition, the fitted Gauss functions for every wrinkle were integrated in order to compare their area with the corresponding area of die cavity, so as to obtain the appropriate process parameters for the useful wrinkle, which can be formed in advance and then flatted in the calibration stage.

  16. Simulation of Aluminum Powder in Tube Compaction Using Equal Channel Angular Extrusion

    Science.gov (United States)

    Haghighi, Reza Derakhshandeh; Jahromi, Ahmad Jenabali; Jahromi, Behnam Esfandiar

    2012-02-01

    Aluminum powder in tube compaction with a 25 mm front plug through equal channel angular extrusion (ECAE) at room temperature was modeled using the finite element analysis package ABAQUS. The Gurson model was used in modeling this process. 2-D simulations in a 90° angle die showed better consolidation of powder near the inner edge of the die than the outer edge after one pass of ECAE but almost full densification occurs after two passes. The effect of hydrostatic pressure on densification of the powder was investigated by using two plugs varying in length dimension. The results obtained from the simulations were also compared with experiments conducted to compact aluminum powder with mean particle diameter of 45 μm. Optical microscopy, microhardness test, and density measurements confirmed the simulations. The simulations were extended to powder compaction in a 60° and 120° angle die. It was found that one pass of ECAE is sufficient to consolidate the aluminum powder completely and uniformly in a 60° angle die, whereas the material is still porous in a 120° angle die.

  17. Relationship of aging and nutritional status to innate immunity in tube-fed bedridden patients.

    Science.gov (United States)

    Takeuchi, Yoshiaki; Tashiro, Tomoe; Yamamura, Takuya; Takahashi, Seiichiro; Katayose, Kozo; Kohga, Shin; Takase, Mitsunori; Imawari, Michio

    2017-01-01

    Aging and malnutrition are known to influence immune functions. The aim of this study was to investigate the relationship of aging and malnutrition to innate immune functions in tube-fed bedridden patients. A cross-sectional survey was performed in 71 tube-fed bedridden patients aged 50-95 years (mean age±SD, 80.2±8.5 years) with serum albumin concentrations between 2.5 and 3.5 g/dL. We evaluated associations of age and nutritional variables with natural-killer cell activity, neutrophilphagocytic activity, and neutrophil-sterilizing activity. Nutritional variables included body mass index, weightadjusted energy intake, total lymphocyte count, and serum concentrations of albumin, transferrin, prealbumin, total cholesterol, C-reactive protein, and zinc. Natural-killer cell activity, neutrophil-phagocytic activity, and neutrophil-sterilizing activity were normal or increased in 67 (94%), 63 (89%), and 69 (97%) patients, respectively. Multiple linear regression analysis with a backward elimination method showed that natural-killer cell activity correlated negatively with aging and lymphocyte counts (paging, body mass index, transferrin, and lymphocyte counts.

  18. Magnetism-Enhanced Monolith-Based In-Tube Solid Phase Microextraction.

    Science.gov (United States)

    Mei, Meng; Huang, Xiaojia; Luo, Qing; Yuan, Dongxin

    2016-02-02

    Monolith-based in-tube solid phase microextraction (MB/IT-SPME) has received wide attention because of miniaturization, automation, expected loading capacity, and environmental friendliness. However, the unsatisfactory extraction efficiency becomes the main disadvantage of MB/IT-SPME. To overcome this circumstance, magnetism-enhanced MB/IT-SPME (ME-MB/IT-SPME) was developed in the present work, taking advantage of magnetic microfluidic principles. First, modified Fe3O4 nanoparticles were mixed with polymerization solution and in situ polymerized in the capillary to obtain a magnetic monolith extraction phase. After that, the monolithic capillary column was placed inside a magnetic coil that allowed the exertion of a variable magnetic field. The effects of intensity of magnetic field, adsorption and desorption flow rate, volume of sample, and desorption solvent on the performance of ME-MB/IT-SPME were investigated in detail. The analysis of six steroid hormones in water samples by the combination of ME-MB/IT-SPME with high-performance liquid chromatography with diode array detection was selected as a paradigm for the practical evaluation of ME-MB/IT-SPME. The application of a controlled magnetic field resulted in an obvious increase of extraction efficiencies of the target analytes between 70% and 100%. The present work demonstrated that application of different magnetic forces in adsorption and desorption steps can effectively enhance extraction efficiency of MB/IT-SPME systems.

  19. Modeling and testing of a tube-in-tube separation mechanism of bodies in space

    Science.gov (United States)

    Michaels, Dan; Gany, Alon

    2016-12-01

    A tube-in-tube concept for separation of bodies in space was investigated theoretically and experimentally. The separation system is based on generation of high pressure gas by combustion of solid propellant and restricting the expansion of the gas only by ejecting the two bodies in opposite directions, in such a fashion that maximizes generated impulse. An interior ballistics model was developed in order to investigate the potential benefits of the separation system for a large range of space body masses and for different design parameters such as geometry and propellant. The model takes into account solid propellant combustion, heat losses, and gas phase chemical reactions. The model shows that for large bodies (above 100 kg) and typical separation velocities of 5 m/s, the proposed separation mechanism may be characterized by a specific impulse of 25,000 s, two order of magnitude larger than that of conventional solid rockets. It means that the proposed separation system requires only 1% of the propellant mass that would be needed for a conventional rocket for the same mission. Since many existing launch vehicles obtain such separation velocities by using conventional solid rocket motors (retro-rockets), the implementation of the new separation system design can reduce dramatically the mass of the separation system and increase safety. A dedicated experimental setup was built in order to demonstrate the concept and validate the model. The experimental results revealed specific impulse values of up to 27,000 s and showed good correspondence with the model.

  20. Impulse Generation Mechanisms in a Laser-Driven In-Tube Accelerator

    Science.gov (United States)

    Choi, Jeong-Yeol; Kang, Ki-Ha; Sasoh, Akihiro; Jeung, In-Seuck; Urabe, Naohide; Kleine, Harald

    To enhance laser-propulsion thrust performance, a unique Laser-driven In-Tube Accelerator (LITA) has been developed. This paper numerically analyzes the impulse generation mechanisms in LITA. For this purpose, a LITA performance experiment was conducted in atmospheric air with a projectile installed on a ballistic pendulum to calibrate the numerical approximations. We conducted experimental flow visualization by framing shadowgraph and computational fluid dynamics solving the axi-symmetric Euler equation applied to an ideal gas. The results show that a laser-driven blast wave is generated by a spherical hot gas core where the supplied laser energy is absorbed first. The effect of confinement by the tube or shroud wall is confirmed. The impulse production is established not only from the interaction between the incident blast wave and projectile, but also from the following repetitive pressure waves. Assuming that about 30% of the input laser energy is absorbed by the working air, both the impulse and peak pressure agrees quantitatively between the experiment and numerical simulation.

  1. Effects of the difference in tube voltage of the CT scanner on dose calculation

    CERN Document Server

    Rhee, Dong Joo; Moon, Young Min; Kim, Jung Ki; Jeong, Dong Hyeok

    2015-01-01

    Computed Tomography (CT) measures the attenuation coefficient of an object and converts the value assigned to each voxel into a CT number. In radiation therapy, CT number, which is directly proportional to the linear attenuation coefficient, is required to be converted to electron density for radiation dose calculation for cancer treatment. However, if various tube voltages were applied to take the patient CT image without applying the specific CT number to electron density conversion curve, the accuracy of dose calculation would be unassured. In this study, changes in CT numbers for different materials due to change in tube voltage were demonstrated and the dose calculation errors in percentage depth dose (PDD) and a clinical case were analyzed. The maximum dose difference in PDD from TPS dose calculation and Monte Carlo simulation were 1.3 % and 1.1 % respectively when applying the same CT number to electron density conversion curve to the 80 kVp and 140 kVp images. In the clinical case, the different CT nu...

  2. Irradiation stability and cytotoxicity of gold nanoparticles for radiotherapy

    OpenAIRE

    Zhang, Xiao-Dong; Guo, Mei-Li; Wu, Hong-Ying; Sun, Yuan-Ming; Ding, Yan-Qiu; Feng, Xin; Zhang, Liang-An

    2009-01-01

    Gold nanoparticles are promising as a kind of novel radiosensitizer in radiotherapy. If gold nanoparticles are shown to have good irradiation stability and biocompatibility, they would play an important role in radiotherapy. In this work, we investigated irradiation effects of gold nanoparticles under 2–10 kR gamma irradiation and cytotoxicity of gold nanoparticles with human K562 cells by using Cell Titre-Glo™ luminescent cell viability assay. The results revealed that gamma irradiation had ...

  3. Early Yellowstone hotspot magmatism and gold metallogeny

    Science.gov (United States)

    Hames, Willis; Unger, Derick; Saunders, James; Kamenov, George

    2009-11-01

    High-grade epithermal gold deposits in the Northern Great Basin have long been associated with regional Miocene basaltic to rhyolitic volcanism. Previous models for the low-sulfidation epithermal gold ores in this region have generally portrayed the bimodal magmas as a source of heat to drive large-scale convection of meteoritic water that leached gold from crustal sources and deposited it in hydrothermal vein systems, or required that the gold evolve from fractionated silicic magmas. New data of the present study indicate a more direct genetic link to the plume-related basaltic magmas of the region. Laser 40Ar/ 39Ar incremental heating plateau ages for single crystals of adularia from several of these low-sulfidation epithermal gold deposits range from 16.6 Ma to 15.5 Ma. Adularia from the Jumbo deposit yields three concordant plateau ages with a combined statistical result of 16.54 ± 0.04 Ma (95% confidence level, MSWD = 0.23). Plateau ages for adularia from other deposits in the region, and from gold-bearing veins in the Owyhee Mountains of southwestern Idaho, yield similar ages up to ~16.5 Ma, however some veins are as young as ca. 15.5 Ma and the grain-to-grain ages for a given sample can vary by up to ca. 0.5 Ma. Observed variations in age among the adularia crystals of a given rock sample indicate varying amounts of extraneous argon, and also loss of radiogenic 40Ar, among the population of grains for a particular sample. The single-crystal results are interpreted to indicate a 16.5-15.5 Ma interval for formation of gold-bearing adularia veins in the region. The initiation and duration of this gold-forming event appears contemporaneous (within uncertainties) with the basaltic volcanism at the Steens Mountain section and an ensuing one-million-year episode of basaltic volcanism from multiple centers in the region ( Brueseke et al., 2007). Trace amounts of lead are alloyed with gold in the deposits studied. The isotopic compositions of this lead are not

  4. Photoluminescence of hollow gold-silver bimetallic nanoparticles

    OpenAIRE

    Weon-Sik Chae; Hee-Ok Lee; Seung-Lim Oh

    2011-01-01

    Hollow gold nanoparticles including silver were prepared by the galvanic replacement reaction of silver nanoparticles by gold. The resulting hollow gold-silver bimetallic nanoparticles show notable blue-green emissions, which are studied using steady-state and time-resolved spectroscopy.

  5. Controlled synthesis and optical properties of pure gold nanoparticles

    NARCIS (Netherlands)

    Singh, A.K.; Rai, A.K.; Bicanic, D.D.

    2009-01-01

    Gold nanoparticles were synthesized by laser ablation of a gold metallic disc at wavelengths of 532 nm and 355 nm with 7 ns pulse duration in the pure water. The colloidal gold nanoparticles were characterized by ultraviolet-visible absorption spectroscopy, transmission electron microscopy, and

  6. Controlled synthesis and optical properties of pure gold nanoparticles

    NARCIS (Netherlands)

    Singh, A.K.; Rai, A.K.; Bicanic, D.D.

    2009-01-01

    Gold nanoparticles were synthesized by laser ablation of a gold metallic disc at wavelengths of 532 nm and 355 nm with 7 ns pulse duration in the pure water. The colloidal gold nanoparticles were characterized by ultraviolet-visible absorption spectroscopy, transmission electron microscopy, and fluo

  7. Gold nanoparticles: preparation, functionalisation and applications in biochemistry and immunochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Dykman, Lev A; Bogatyrev, Vladimir A [Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences (Russian Federation)

    2007-02-28

    The review summarises data on the synthesis and functionalisation of gold nanoparticles and their applications in biological investigations. Particular attention is given to applications of colloidal gold in solid-phase assays, immunoassay and studies of biologically active compounds by vibrational spectroscopy. A special section deals with the use of gold nanoparticles as antigen carriers in immunisation.

  8. The Largest Gold Mine in Asia was Found in Gansu

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>Recently,at Yangshan,a place bordering with Shaanxi and Sichuan provinces,of Wen County in Gansu Province,the largest gold mine in Asia was found with proved gold reserve of 308 tons,changing the history of having no super large independent gold deposits over 200 tons in China.

  9. Photoluminescence of hollow gold-silver bimetallic nanoparticles

    Directory of Open Access Journals (Sweden)

    Weon-Sik Chae

    2011-12-01

    Full Text Available Hollow gold nanoparticles including silver were prepared by the galvanic replacement reaction of silver nanoparticles by gold. The resulting hollow gold-silver bimetallic nanoparticles show notable blue-green emissions, which are studied using steady-state and time-resolved spectroscopy.

  10. Gold-coated nanoparticles for use in biotechnology applications

    Science.gov (United States)

    Berning, Douglas E.; Kraus, Jr., Robert H.; Atcher, Robert W.; Schmidt, Jurgen G.

    2007-06-05

    A process of preparing gold-coated magnetic nanoparticles is disclosed and includes forming a suspension of magnetic nanoparticles within a suitable liquid, adding an amount of a reducible gold compound and a reducing agent to the suspension, and, maintaining the suspension for time sufficient to form gold-coated magnetic nanoparticles.

  11. 21 CFR 872.3350 - Gold or stainless steel cusp.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gold or stainless steel cusp. 872.3350 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3350 Gold or stainless steel cusp. (a) Identification. A gold or stainless steel cusp is a prefabricated device made of austenitic alloys or...

  12. Gold in meteorites and in the earth's crust

    Science.gov (United States)

    Jones, Robert Sprague

    1968-01-01

    The reported gold contents of meteorites range from 0.0003 to 8.74 parts per million. Gold is siderophilic, and the greatest amounts in meteorites are in the iron phases. Estimates ,of the gold content of the earth's crust are in the range of 0.001 to 0.006 parts per million.

  13. Noble gases, K, U, Th, and Pb in native gold

    Science.gov (United States)

    Engster, O.; Niedermann, S.; Thalmann, C.; Frei, R.; Kramers, J.; KräHenbühl, U.; Liu, Y. Z.; Hofmann, B.; Boer, R. H.; Reimold, W. U.; Bruno, L.

    1995-12-01

    We present determinations of the noble gas and Pb isotopic abundances and of K, Th, and U concentrations of native gold. Our results demonstrate that gold is an excellent carrier for crustal volatiles, but direct dating of gold using the U, Th-4He, 40K-40Ar, and U fission Xe methods was not successful for various reasons. The main significance of this work is the great sensitivity of gold for trapped gases as well as for gases that were produced in situ which gives the prospects of using gold and its fluid and solid inclusions for the study of paleogas composition. Numerous nuclear effects characterize the noble gas inventory of placer gold from Switzerland and Italy, vein gold from Italy, South Africa, and Venezuela, and lode gold from South Africa. The degassing patterns obtained by mass spectrometry show a low-temperature release of volatiles around 500°C from fluid inclusions mainly in vein gold and a high-temperature release from solid inclusions and the gold itself. The low-temperature volatiles represent species that were trapped when the gold crystallized. We investigated the following trapped species: the isotopes of He, Ne, Ar, Kr, Xe, and Pb, and the abundances of K, U, Th, H2O, and CO2. The crustal gases trapped by gold comprise 3He from 6Li(n,α)3H → β- → 3He, 4He and 40Ar from the U, Th, and K decay, and Xe from 238U fission. We observe 4He/40Ar = 3.9 for the radiogenic trapped gases of tertiary gold and a ratio of 1.4 for Archean gold. These ratios are consistent with the production ratios from U and K at the respective times and demonstrate that gold can be used as a sampler of ancient atmospheric gases. The concentrations of U and Th range from a few parts per billion to a few parts per million, and those of K and Pb range up to some tens of parts per million. The antiquity of trapped Pb is indicated by the Pb-Pb model age of about 3000 Ma for the lead extracted from vein gold and quartz of the Lily gold mine (South Africa). Gold also

  14. The Physico-Chemical Conditions for Mobilization of Gold in Mobin Gold Deposit, Southwest Hunan, China

    Institute of Scientific and Technical Information of China (English)

    谷俐; 杨华; 戴塔根; 刘利萍

    2002-01-01

    Experiments on water-rock interaction were carried out on wall-rock samples from the Mobin gold deposit, Southwest Hunan, China, with the aim of determining the optimum physical and chemical conditions for the mobilization of gold in solution. Results indicate that gold is most easily mobilized from the wall rock-tuffaceous slate of the Mobin Deposit. Mobi lization is optimized if fluids are neutral to slightly alkaline and contain both chlorine and sulphur ions at the concentration and composition of about [0.25M (NH4)2S + 1M NaCl]. The amount of gold leached from the tuffaceous slate increases with temperature although the effect decreases above about 200℃ .

  15. Infrared light-absorbing gold/gold sulfide nanoparticles induce cell death in esophageal adenocarcinoma

    Science.gov (United States)

    Li, Yan; Gobin, Andre M; Dryden, Gerald W; Kang, Xinqin; Xiao, Deyi; Li, Su Ping; Zhang, Guandong; Martin, Robert CG

    2013-01-01

    Gold nanoparticles and near infrared-absorbing light are each innocuous to tissue but when combined can destroy malignant tissue while leaving healthy tissue unharmed. This study investigated the feasibility of photothermal ablation therapy for esophageal adenocarcinoma using chitosan-coated gold/gold sulfide (CS-GGS) nanoparticles. A rat esophagoduodenal anastomosis model was used for the in vivo ablation study, and three human esophageal cell lines were used to study the response of cancer cells and benign cells to near infrared light after treatment with CS-GGS. The results indicate that both cancerous tissue and cancer cells took up more gold nanoparticles and were completely ablated after exposure to near infrared light. The benign tissue and noncancerous cells showed less uptake of these nanoparticles, and remained viable after exposure to near infrared light. CS-GGS nanoparticles could provide an optimal endoluminal therapeutic option for near infrared light ablation of esophageal cancer. PMID:23818775

  16. Self-assembled gold nanoparticles on functionalized gold(111) studied by scanning tunneling microscopy

    Institute of Scientific and Technical Information of China (English)

    PENG, Zhang-Quan; WANG, Er-Kang

    2000-01-01

    Nanogold colloidal solutions are prepared by the reduction of HAuClO4 with sodium citrate and sodium borohydride. 4- Aminothiophenol (ATP) self-assembled monolayers (SAMs) are formed on gold(111) surface, on which gold nanoparticles are immobilized and a sub-monolayer of the particles appears. This sub-monolayer of gold nanoparticles is characterized with scanning tunneling microscopy (STM), and a dual energy barrier tunneling model is proposed to explain the imgeability of the gold nanoparticles by STM. This model can also be used to construct multiple energy barrier structure on solid/ liquid interface and to evaluate the electron transport ability of some organic monolayers with the aid of electrochemical method.

  17. Gold-Catalyzed Reactions via Cyclopropyl Gold Carbene-like Intermediates.

    Science.gov (United States)

    Dorel, Ruth; Echavarren, Antonio M

    2015-08-07

    Cycloisomerizations of 1,n-enynes catalyzed by gold(I) proceed via electrophilic species with a highly distorted cyclopropyl gold(I) carbene-like structure, which can react with different nucleophiles to form a wide variety of products by attack at the cyclopropane or the carbene carbons. Particularly important are reactions in which the gold(I) carbene reacts with alkenes to form cyclopropanes either intra- or intermolecularly. In the absence of nucleophiles, 1,n-enynes lead to a variety of cycloisomerized products including those resulting from skeletal rearrangements. Reactions proceeding through cyclopropyl gold(I) carbene-like intermediates are ideally suited for the bioinspired synthesis of terpenoid natural products by the selective activation of the alkyne in highly functionalized enynes or polyenynes.

  18. Plasmonic biocompatible silver-gold alloyed nanoparticles.

    Science.gov (United States)

    Sotiriou, Georgios A; Etterlin, Gion Diego; Spyrogianni, Anastasia; Krumeich, Frank; Leroux, Jean-Christophe; Pratsinis, Sotiris E

    2014-11-14

    The addition of Au during scalable synthesis of nanosilver drastically minimizes its surface oxidation and leaching of toxic Ag(+) ions. These biocompatible and inexpensive silver-gold nanoalloyed particles exhibit superior plasmonic performance than commonly used pure Au nanoparticles, and as such these nanoalloys have great potential in theranostic applications.

  19. CAS expert receives Tribology Gold Medal

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Prof. XUE Qunji, a senior expert in tribology from the CAS Lanzhou Institute of Chemical Physics (L1CP) and member of the Chinese Academy of Engineering, received the Tribology Gold Medalfor 2011 on February 27, 2012 in Beijing. As one of the world's most outstanding and influential tribologists in the last forty years, Prof.

  20. Opposition to gold mining at Bergama, Turkey

    NARCIS (Netherlands)

    M. Arsel (Murat)

    2012-01-01

    textabstractIntroduction For much of the 1990s, the tourist town of Bergama was the epicentre of Turkey's most effective and visible environmental social movement against a multinational mining corporation aiming to establish the first modern gold mine in the country. Bringing

  1. Optical properties of spherical gold mesoparticles

    DEFF Research Database (Denmark)

    Evlyukhin, A. B.; Kuznetsov, A. I.; Novikov, S. M.;

    2012-01-01

    Optical properties of spherical gold particles with diameters of 150-650 nm (mesoparticles) are studied by reflectance spectroscopy. Particles are fabricated by laser-induced transfer of metallic droplets onto metal and dielectric substrates. Contributions of higher multipoles (beyond the quadrup...

  2. Opposition to gold mining at Bergama, Turkey

    NARCIS (Netherlands)

    M. Arsel (Murat)

    2012-01-01

    textabstractIntroduction For much of the 1990s, the tourist town of Bergama was the epicentre of Turkey's most effective and visible environmental social movement against a multinational mining corporation aiming to establish the first modern gold mine in the country. Bringing relatively prosperous

  3. Poly-thiosemicarbazide membrane for gold recovery

    KAUST Repository

    Villalobos, Luis Francisco

    2014-11-01

    A novel polymeric membrane adsorber with a high density of adsorption sites that can selectively capture Au(III) ions, is proposed as an efficient alternative to recover gold from dilute solutions. Poly-thiosemicarbazide (PTSC), a polymer that contains one chelate site per monomeric unit, was used to fabricate the membranes. This polymer can be easily processed into membranes by a phase inversion technique, resulting in an open and interconnected porous structure suitable for high flux liquid phase applications. This method overcomes the usual low capacities of membrane adsorbents by selecting a starting material that contains the adsorption sites within it, therefore avoiding the necessity to add an external agent into the membrane matrix. The resulting mechanically stable PTSC membranes can operate in a pressure driven permeation process, which eliminates the diffusion limitations commonly present in packed column adsorption processes. This process can selectively recover 97% of the gold present in a solution containing a 9-fold higher copper concentration, while operating at a flux as high as 1868 L/m2 h. The maximum gold uptake measured without sacrificing the mechanical stability of the membrane was 5.4 mmol Au/g. Furthermore the gold can be easily eluted from the membrane with a 0.1 M thiourea solution and the membrane can be reused for at least three cycles without any decrease in its performance. Finally, the ability of this membrane for recovering metals from real-life samples, like seawater and tap water, was tested with promising results.

  4. Photosynthetic light reactions at the gold interface

    NARCIS (Netherlands)

    Kamran, Muhammad

    2014-01-01

    In the project described in this thesis we studied a simple bio-electronic device for solar energy conversion by surface-assembly of photosynthetic pigment-protein complexes on a bare gold-electrode. Optical excitation of the photosynthetic pigments gives rise to charge separation in the so-called

  5. Surface interactions between gold nanoparticles and biochar

    Science.gov (United States)

    Engineered nanomaterials are directly applied to agricultural soils as a part of pesticide/fertilize formulations and sludge/manure amendments. Yet, no prior reports are available on the extent and reversibility of gold nanoparticles (nAu) retention by soil components including charcoal black carbo...

  6. Photosynthetic light reactions at the gold interface

    NARCIS (Netherlands)

    Kamran, Muhammad

    2014-01-01

    In the project described in this thesis we studied a simple bio-electronic device for solar energy conversion by surface-assembly of photosynthetic pigment-protein complexes on a bare gold-electrode. Optical excitation of the photosynthetic pigments gives rise to charge separation in the so-called r

  7. Photothermal fluctuation spectroscopy on gold nanoparticle dimers

    Energy Technology Data Exchange (ETDEWEB)

    Waehnert, Miriam; Neubauer, Nils; Raduenz, Romy; Cichos, Frank [Molecular Nanophotonics Group, University of Leipzig, Linnestrasse 5, 04103 Leipzig (Germany)

    2009-07-01

    To measure distance changes on the nanoscale, FRET (Fluorescence resonance energy transfer) is a heavily applied technique in biophysical studies. The upper limit of distance fluctuations being measured with this method is about 10 nm. Furthermore it suffers from photochemical degradation mechanisms like blinking and bleaching of the energy transferring dye molecules. We report on recent experiments using pairs of gold nanoparticles as absorbing markers replacing dye molecules. Gold particles are strongly interacting with light, if they are excited near the plasmon resonance. The resulting dipoles of two closely spaced gold nanoparticles can couple to form a new resonance, which appears in the absorption as a distinct feature. The strength of this absorption depends on the distance of the two particles and is visible up to a few 10 nm, which clearly exceeds the lengthscale of FRET. The gold nanoparticles are detected by photothermal heterodyne detection, using the release of heat from the absorbing particles to create a local refractive index change around them, which can be probed with a confocal laser scanning setup. Due to the plasmon coupling a fluctuating distance will result in a fluctuating photothermal signal. Numerical analyses of the spectra together with first experimental results will be presented.

  8. Unambiguous optical characterization of nanocolloidal gold films

    NARCIS (Netherlands)

    Wormeester, Herbert; Kooij, E. Stefan; Poelsema, Bene

    2003-01-01

    The thin island film theory developed by Bedeaux and Vlieger [Optical Properties of Surface (Imperial College Press (2002)], is used to unambiguously analyze spectroscopic ellipsometry spectra of thin layers of nanocolloidal gold particles on silicon substrates covered by a natural oxide layer, for

  9. High-energy band structure of gold

    DEFF Research Database (Denmark)

    Christensen, N. Egede

    1976-01-01

    The band structure of gold for energies far above the Fermi level has been calculated using the relativistic augmented-plane-wave method. The calculated f-band edge (Γ6-) lies 15.6 eV above the Fermi level is agreement with recent photoemission work. The band model is applied to interpret...

  10. Dynamic breaking of a single gold bond

    DEFF Research Database (Denmark)

    Pobelov, Ilya V.; Lauritzen, Kasper Primdal; Yoshida, Koji

    2017-01-01

    . Conversely, if the force is loaded rapidly it is more likely that the maximum breaking force is measured. Paradoxically, no clear differences in breaking force were observed in experiments on gold nanowires, despite being conducted under very different conditions. Here we explore the breaking behaviour...

  11. GOLD WEIGHTS IN FACIAL PARALYSIS (REVISITED)

    NARCIS (Netherlands)

    ZECHA, PJ; ROBINSON, PH; VANOORT, RP; COENRAADS, PJ

    1994-01-01

    A retrospective study of 11 patients with facial paralysis was undertaken. Correction of lagophthalmos was accomplished by inserting a dental gold weight into the upper eyelid. All weights were assessed and adjusted to fit the patient's individual need. The primary objective was to achieve adequate

  12. GOLD WEIGHTS IN FACIAL PARALYSIS (REVISITED)

    NARCIS (Netherlands)

    ZECHA, PJ; ROBINSON, PH; VANOORT, RP; COENRAADS, PJ

    A retrospective study of 11 patients with facial paralysis was undertaken. Correction of lagophthalmos was accomplished by inserting a dental gold weight into the upper eyelid. All weights were assessed and adjusted to fit the patient's individual need. The primary objective was to achieve adequate

  13. Plasmonic photothermal therapy (PPTT) using gold nanoparticles.

    Science.gov (United States)

    Huang, Xiaohua; Jain, Prashant K; El-Sayed, Ivan H; El-Sayed, Mostafa A

    2008-07-01

    The use of lasers, over the past few decades, has emerged to be highly promising for cancer therapy modalities, most commonly the photothermal therapy method, which employs light absorbing dyes for achieving the photothermal damage of tumors, and the photodynamic therapy, which employs chemical photosensitizers that generate singlet oxygen that is capable of tumor destruction. However, recent advances in the field of nanoscience have seen the emergence of noble metal nanostructures with unique photophysical properties, well suited for applications in cancer phototherapy. Noble metal nanoparticles, on account of the phenomenon of surface plasmon resonance, possess strongly enhanced visible and near-infrared light absorption, several orders of magnitude more intense compared to conventional laser phototherapy agents. The use of plasmonic nanoparticles as highly enhanced photoabsorbing agents has thus introduced a much more selective and efficient cancer therapy strategy, viz. plasmonic photothermal therapy (PPTT). The synthetic tunability of the optothermal properties and the bio-targeting abilities of the plasmonic gold nanostructures make the PPTT method furthermore promising. In this review, we discuss the development of the PPTT method with special emphasis on the recent in vitro and in vivo success using gold nanospheres coupled with visible lasers and gold nanorods and silica-gold nanoshells coupled with near-infrared lasers.

  14. WILLIAM GOLDING'S NOVEL--THE BACKWARD LOOK.

    Science.gov (United States)

    PECK, CAROL FAULKNER

    THE "SURPRISE ENDINGS" IN EACH OF WILLIAM GOLDING'S FIRST FOUR NOVELS OCCUR WHEN THE POINT OF VIEW SHIFTS FROM THE LIMITED WORLD OF THE NOVEL TO THE UNLIMITED WORLD OF REALITY. THE BOYS' RESCUE BY THE UNCOMPREHENDING OFFICER IN "LORD OF THE FLIES," REFOCUSES AND REINFORCES ALL THAT PRECEDES IT, AND THE FABLE, SUPERIMPOSED UPON REAL LIFE, BECOMES…

  15. Gold ratio and a trigonometric identity

    OpenAIRE

    Shevelev, Vladimir

    2009-01-01

    We give two proofs of the identity $$\\sqrt{\\frac{\\cos\\frac{2\\pi}{5}} {\\cos\\frac{\\pi}{5}}}+\\sqrt{\\frac{\\cos\\frac{\\pi}{5}} {\\cos\\frac{2\\pi}{5}} }=\\sqrt{5},$$ using and not using the gold ratio.

  16. Heterodyne holographic microscopy of gold particles

    CERN Document Server

    Atlan, Michael; Desbiolles, Pierre; Absil, Emilie; Tessier, Gilles; Coppey-Moisan, Maité

    2007-01-01

    We report experimental results on heterodyne holographic microscopy of subwavelength-sized gold particles. The apparatus uses continuous green laser illumination of the metal beads in a total internal reflection configuration for dark-field operation. Detection of the scattered light at the illumination wavelength on a charge-coupled device array detector enables 3D localization of brownian particles in water

  17. Hydroquinone Based Synthesis of Gold Nanorods.

    Science.gov (United States)

    Picciolini, Silvia; Mehn, Dora; Ojea-Jiménez, Isaac; Gramatica, Furio; Morasso, Carlo

    2016-08-10

    Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the synthetic methods for the preparation of gold nanorods are still not fully optimized. In this paper we describe a new, highly efficient, two-step protocol based on the use of hydroquinone as a mild reducing agent. Our approach allows the preparation of nanorods with a good control of size and aspect ratio (AR) simply by varying the amount of hexadecyl trimethylammonium bromide (CTAB) and silver ions (Ag(+)) present in the "growth solution". By using this method, it is possible to markedly reduce the amount of CTAB, an expensive and cytotoxic reagent, necessary to obtain the elongated shape. Gold nanorods with an aspect ratio of about 3 can be obtained in the presence of just 50 mM of CTAB (versus 100 mM used in the standard protocol based on the use of ascorbic acid), while shorter gold nanorods are obtained using a concentration as low as 10 mM.

  18. Paleoproterozoic Sediment- hosted Gold Deposits in Eastern Liaoning, Northeast China: Implications for Gold Exploration

    Institute of Scientific and Technical Information of China (English)

    Yang Dejiang

    2001-01-01

    Gold deposits in eastern Liaoning, northeast China are hosted in the middle and upper parts of a Paleoproterozoic volcanic - sedimentary succession, which consists of interlayered carbonates and fine - grained clastics. This paper discusses the geological features of ore - bearing formations, ore- controlling structures and metallogenetic characteristics. Analysis of ore - controlling factors suggested that the schists from the Gaixian formatyion, syngenetic faults and ductile shear zones are principal ore controls over mineralization and thereafter indicators for gold exploration.

  19. A Comparative Study of William Golding'S Four Novels%Comparative Study of William Golding'S Four Novels

    Institute of Scientific and Technical Information of China (English)

    崔晓强

    2008-01-01

    With his keen insight,William Golding becomes very conscious of the human heart and the necessity that we become aware of this darkness we are to save ourselves.All his novels,attempt to deal with the essential human condition.All Golding 's novels, products of his peculiar literary temperament and habit,are reactive experiments.Each of them represents a response to a specific book by an early writer.

  20. Reactivity of Cys4 Zinc Finger Domains with Gold(III) Complexes : Insights into the Formation of "Gold Fingers"

    NARCIS (Netherlands)

    Jacques, Aurélie; Lebrun, Colette; Casini, Angela; Kieffer, Isabelle; Proux, Olivier; Latour, Jean-Marc; Sénèque, Olivier

    2015-01-01

    Gold(I) complexes such as auranofin or aurothiomalate have been used as therapeutic agents for the treatment of rheumatoid arthritis for several decades. Several gold(I) and gold(III) complexes have also shown in vitro anticancer properties against human cancer cell lines, including cell lines resis

  1. Reactivity of Cys4 Zinc Finger Domains with Gold(III) Complexes : Insights into the Formation of "Gold Fingers"

    NARCIS (Netherlands)

    Jacques, Aurélie; Lebrun, Colette; Casini, Angela; Kieffer, Isabelle; Proux, Olivier; Latour, Jean-Marc; Sénèque, Olivier

    2015-01-01

    Gold(I) complexes such as auranofin or aurothiomalate have been used as therapeutic agents for the treatment of rheumatoid arthritis for several decades. Several gold(I) and gold(III) complexes have also shown in vitro anticancer properties against human cancer cell lines, including cell lines

  2. Direct formation of gold nanorods on surfaces using polymer-immobilised gold seeds

    Directory of Open Access Journals (Sweden)

    Majid K. Abyaneh

    2016-06-01

    Full Text Available Herein, we present the formation of gold nanorods (GNRs on novel gold–poly(methyl methacrylate (Au–PMMA nanocomposite substrates with unprecedented growth control through the polymer molecular weight (Mw and gold-salt-to-polymer weight ratio. For the first time, GNRs have been produced by seed-mediated direct growth on surfaces that were pre-coated with polymer-immobilised gold seeds. A Au–PMMA nanocomposite formed by UV photoreduction has been used as the gold seed. The influence of polymer Mw and gold concentration on the formation of GNRs has been investigated and discussed. The polymer nanocomposite formed with a lower Mw PMMA and 20 wt % gold salt provides a suitable medium for growing well-dispersed GNRs. In this sample, the average dimension of produced GNRs is 200 nm in length with aspect ratios up to 10 and a distribution of GNRs to nanoparticles of nearly 22%. Suitable characterization techniques such as AFM and SEM have been used to support concept of the proposed growth method.

  3. Occurrences of dendritic gold at the McLaughlin Mine hot-spring gold deposit

    Science.gov (United States)

    Sherlock, R. L.; Lehrman, N. J.

    1995-06-01

    Two styles of gold dendrites are variably developed at the McLaughlin Mine. The most abundant occurrence is hosted by amber-coloured hydrocarbon-rich opal. Silica likely precipitated from a boiling hydrothermal fluid and complexed with immiscible hydrocarbons forming an amorphous hydrocarbon-silica phase. This phase likely scavenged particulate gold by electrostatic attraction to the hydrocarbon-silica phase. The dendritic nature of the gold is secondary and is the result of dewatering of the amorphous hydrocarbon-silica phase and crystallization of gold into syneresis fractures. The second style of dendritic gold is hosted within vein swarms that focused large volumes of fluid flow. The dendrites occur along with hydrocarbon-rich silica at the upper contact of the vein margins which isolated the dendrites allowing sufficient time for them to grow. In a manner similar to the amber-coloured opal, the dendrites may have formed by scavenging particulate gold by electrostatic attraction to the hydrocarbon-silica phase.

  4. Experimental Study on Gold Dissolution from Hosting Minerals of the Hadamengou Gold Deposit and the Implications

    Institute of Scientific and Technical Information of China (English)

    LI Qiangzhi; YAN Fengzeng; WANG Xinhu

    2008-01-01

    The Hadamengou gold deposit is located in western part of the northern margin of the NorthChina craton. It is a hydrothermai deposit related to alkaline magmatism. Dissolution of Au, Fe frompyrite and iron oxide (including magnetite and hematite) individual minerals in the three main types ofore shows: in iron oxides (magnetite and hematite), Au and Fe were dissolved simultaneously and theirsolubilities are positively correlated, which means Au is mainly chemical-bonded (lattice gold) and/orcolloidal-adsorbed in iron oxides; while in pyrite, on the contrary, Au dissolution obviously lags behindFe and the solubility of Au shows negative relationship with that of Fe, which indicates Au is mainlyhosted as grains of elemental gold (or native gold) within pyrite. Previous studies revealed that theHadamengou gold deposit is characterized by intensive K-feldspathization and holds high content ofiron oxides occasionally replaced by sulfides, which was caused by oxidizing K-enriched alkaline fluidsunder a stretching geodynamic setting. These geological features, together with the high Au-content iniron oxides, comparable with that of the Olympic Dam deposit in South Australia, suggest that thisdeposit is the first example of iron oxide-type gold deposits in China.

  5. Applications of gold nanoparticles in cancer nanotechnology

    Directory of Open Access Journals (Sweden)

    Weibo Cai

    2008-09-01

    Full Text Available Weibo Cai1,2, Ting Gao3, Hao Hong1, Jiangtao Sun11Departments of Radiology and Medical Physics, School of Medicine and Public Health, University of Wisconsin – Madison, Madison, Wisconsin, USA; 2University of Wisconsin Paul P. Carbone Comprehensive Cancer Center, Madison, Wisconsin, USA; 3Tyco Electronics Corporation, 306 Constitution Drive, Menlo Park, California, USAAbstract: It has been almost 4 decades since the “war on cancer” was declared. It is now generally believed that personalized medicine is the future for cancer patient management. Possessing unprecedented potential for early detection, accurate diagnosis, and personalized treatment of cancer, nanoparticles have been extensively studied over the last decade. In this review, we will summarize the current state-of-the-art of gold nanoparticles in biomedical applications targeting cancer. Gold nanospheres, nanorods, nanoshells, nanocages, and surface enhanced Raman scattering nanoparticles will be discussed in detail regarding their uses in in vitro assays, ex vivo and in vivo imaging, cancer therapy, and drug delivery. Multifunctionality is the key feature of nanoparticle-based agents. Targeting ligands, imaging labels, therapeutic drugs, and other functionalities can all be integrated to allow for targeted molecular imaging and molecular therapy of cancer. Big strides have been made and many proof-of-principle studies have been successfully performed. The future looks brighter than ever yet many hurdles remain to be conquered. A multifunctional platform based on gold nanoparticles, with multiple receptor targeting, multimodality imaging, and multiple therapeutic entities, holds the promise for a “magic gold bullet” against cancer.Keywords: gold nanoparticles, cancer, nanotechnology, optical imaging, nanomedicine, molecular therapy

  6. Polymer decorated gold nanoparticles in nanomedicine conjugates.

    Science.gov (United States)

    Capek, Ignác

    2017-02-15

    Noble metal, especially gold nanoparticles and their conjugates with biopolymers have immense potential for disease diagnosis and therapy on account of their surface plasmon resonance (SPR) enhanced light scattering and absorption. Conjugation of noble metal nanoparticles to ligands specifically targeted to biomarkers on diseased cells allows molecular-specific imaging and detection of disease. The development of smart gold nanoparticles (AuNPs) that can deliver therapeutics at a sustained rate directly to cancer cells may provide better efficacy and lower toxicity for treating cancer tumors. We highlight some of the promising classes of targeting systems that are under development for the delivery of gold nanoparticles. Nanoparticles designed for biomedical applications are often coated with polymers containing reactive functional groups to conjugate targeting ligands, cell receptors or drugs. Using targeted nanoparticles to deliver chemotherapeutic agents in cancer therapy offers many advantages to improve drug/gene delivery and to overcome many problems associated with conventional radiotherapy and chemotherapy. The targeted nanoparticles were found to be effective in killing cancer cells which were studied using various anticancer assays. Cell morphological analysis shows the changes occurred in cancer cells during the treatment with AuNPs. The results determine the influence of particle size and concentration of AuNPs on their absorption, accumulation, and cytotoxicity in model normal and cancer cells. As the mean particle diameter of the AuNPs decreased, their rate of absorption by the intestinal epithelium cells increased. These results provide important insights into the relationship between the dimensions of AuNPs and their gastrointestinal uptake and potential cytotoxicity. Furthermore gold nanoparticles efficiently convert the absorbed light into localized heat, which can be exploited for the selective laser photothermal therapy of cancer. We also review

  7. Rheumatoid arthritis, gold therapy, contact allergy and blood cytokines

    OpenAIRE

    Svensson, Ake; Möller, Halvor; Björkner, Bert; Bruze, Magnus; Leden, Ido; Theander, Jan; Ohlsson, Kjell; Linder, Carina

    2002-01-01

    Abstract Objective To study the clinical and biochemical effects of a low starting dose for gold therapy in rheumatoid arthritis patients with a contact allergy to gold. Methods Serum cytokines were assayed before and 24 h after the first injection of gold sodium thiomalate (GSTM). Results Contact allergy to gold was found in 4 of 19 patients. Compared to gold-negative patients (starting dose: 10 mg GSTM), there was a larger increase in serum TNFalpha (p < 0.05), sTNF-R1 (NS), and IL-1 ra (p ...

  8. Formation of gold mineralization in ultramafic alkalic magmatic complexes

    Science.gov (United States)

    Ryabchikov, I. D.; Kogarko, L. N.; Sazonov, A. M.; Kononkova, N. N.

    2016-06-01

    Study of mineral inclusions within alluvial gold particles of the Guli Complex (East Siberia) and findings of lode gold in rocks of the same intrusion have demonstrated that gold mineralization occurs in interstitions of both early high-magnesium rocks (dunite) and later alkalic and carbonatite rocks. In dunite the native gold occurs in association with Fe-Ni sulfides (monosulfide solid solution, pentlandite, and heazlewoodite). Formation of the gold-bearing alloys took place under a low oxygen potential over a broad range of temperatures: from those close to 600°C down to below 400°C.

  9. Synthesis, capping and binding of colloidal gold nanoparticles to proteins

    Science.gov (United States)

    Nghiem, Thi Ha Lien; Huyen La, Thi; Hoa Vu, Xuan; Chu, Viet Ha; Hai Nguyen, Thanh; Huan Le, Quang; Fort, Emmanuel; Hoa Do, Quang; Nhung Tran, Hong

    2010-06-01

    Bovine serum albumin (BSA) was used as a stabilizing agent and biofunctionalized layer for water-dispersed gold nanoparticles (NPs) synthesized from metal precursor HAuCl4. The BSA binding to gold NPs was characterized qualitatively and quantitatively by transmission electron microscopy, UV-VIS and FTIR spectrophotometers. HER2 (human epidermal growth factor receptor 2) specific phage antibodies were attached to BSA stabilized gold NPs to form a gold-antibody complex. An ELISA (enzyme-linked immunosorbent assay) test was done to confirm the bioactivity of antibodies attached to gold NPs.

  10. Interventions to reduce wrong blood in tube errors in transfusion: a systematic review.

    Science.gov (United States)

    Cottrell, Susan; Watson, Douglas; Eyre, Toby A; Brunskill, Susan J; Dorée, Carolyn; Murphy, Michael F

    2013-10-01

    This systematic review addresses the issue of wrong blood in tube (WBIT). The objective was to identify interventions that have been implemented and the effectiveness of these interventions to reduce WBIT incidence in red blood cell transfusion. Eligible articles were identified through a comprehensive search of The Cochrane Library, MEDLINE, EMBASE, Cinahl, BNID, and the Transfusion Evidence Library to April 2013. Initial search criteria were wide including primary intervention or observational studies, case reports, expert opinion, and guidelines. There was no restriction by study type, language, or status. Publications before 1995, reviews or reports of a secondary nature, studies of sampling errors outwith transfusion, and articles involving animals were excluded. The primary outcome was a reduction in errors. Study characteristics, outcomes measured, and methodological quality were extracted by 2 authors independently. The principal method of analysis was descriptive. A total of 12,703 references were initially identified. Preliminary secondary screening by 2 reviewers reduced articles for detailed screening to 128 articles. Eleven articles were eventually identified as eligible, resulting in 9 independent studies being included in the review. The overall finding was that all the identified interventions reduced WBIT incidence. Five studies measured the effect of a single intervention, for example, changes to blood sample labeling, weekly feedback, handwritten transfusion requests, and an electronic transfusion system. Four studies reported multiple interventions including education, second check of ID at sampling, and confirmatory sampling. It was not clear which intervention was the most effective. Sustainability of the effectiveness of interventions was also unclear. Targeted interventions, either single or multiple, can lead to a reduction in WBIT; but the sustainability of effectiveness is uncertain. Data on the pre- and postimplementation of

  11. Ni(2+) doped glass ceramic fiber fabricated by melt-in-tube method and successive heat treatment.

    Science.gov (United States)

    Fang, Zaijin; Zheng, Shupei; Peng, Wencai; Zhang, Hang; Ma, Zhijun; Dong, Guoping; Zhou, Shifeng; Chen, Danping; Qiu, Jianrong

    2015-11-02

    Glass ceramic fibers containing Ni(2+) doped LiGa(5)O(8) nanocrystals were fabricated by a melt-in-tube method and successive heat treatment. Fiber precursors were prepared by drawing at high temperature where fiber core glass was melted while fiber clad glass was softened. After heat treatment, LiGa(5)O(8) nanocrystals were precipitated in the fiber core. Excited by 980 nm laser, efficient broadband near-infrared emission was observed in the glass ceramic fiber compared to that of precursor fiber. The melt-in-tube method can realize controllable crystallization and is suitable for fabrication of novel glass ceramic fibers. The Ni(2+)-doped glass ceramic fiber is promising for broadband optical amplification.

  12. Evaluation of QuantiFERON-TB Gold Plus for Detection of Mycobacterium tuberculosis infection in Japan

    Science.gov (United States)

    Yi, Lina; Sasaki, Yuka; Nagai, Hideaki; Ishikawa, Satoru; Takamori, Mikio; Sakashita, Kentaro; Saito, Takefumi; Fukushima, Kiyoyasu; Igarashi, Yuriko; Aono, Akio; Chikamatsu, Kinuyo; Yamada, Hiroyuki; Takaki, Akiko; Mori, Toru; Mitarai, Satoshi

    2016-01-01

    Performance of interferon-γ (IFN-γ) release assays still needs to be improved. The data on the performance of QuantiFERON-TB Gold Plus (QFT-Plus), a new-generation of QFT assay are limited. This study evaluated the diagnostic performance of QFT-Plus, and compared to that of QuantiFERON-TB Gold In-Tube (QFT-GIT). Blood samples were collected from 162 bacteriologically confirmed tuberculosis (TB) patients and 212 Mycobacterium tuberculosis-uninfected volunteers; these samples were then tested with QFT-GIT and QFT-Plus. The IFN-γ concentration of QFT-Plus was lower than that of QFT-GIT in TB patients (p < 0.001). Receiver operating characteristic curves were compared between QFT-GIT and QFT-Plus. Both assays showed area under the curve values over 0.99 without significant difference. Using the conventional cut-off (0.35 IU/mL) for QFT-GIT, QFT-Plus had a lower sensitivity of 91.1% compared to 96.2% (p = 0.008) at its optimum cut-off (0.168 IU/mL) with the same specificity. Moreover, IFN-γ values were significantly reduced with age in QFT-GIT (p = 0.035) but not in QFT-Plus. The diagnostic performance of QFT-Plus was as accurate as that of QFT-GIT despite a lack of TB7.7 antigen and despite the decrease in quantitative values. However, the cut-off value for QFT-Plus should be considered independently from that of QFT-GIT to obtain the best sensitivity without compromising specificity. PMID:27470684

  13. Evaluation of QuantiFERON-TB Gold Plus for Detection of Mycobacterium tuberculosis infection in Japan.

    Science.gov (United States)

    Yi, Lina; Sasaki, Yuka; Nagai, Hideaki; Ishikawa, Satoru; Takamori, Mikio; Sakashita, Kentaro; Saito, Takefumi; Fukushima, Kiyoyasu; Igarashi, Yuriko; Aono, Akio; Chikamatsu, Kinuyo; Yamada, Hiroyuki; Takaki, Akiko; Mori, Toru; Mitarai, Satoshi

    2016-07-29

    Performance of interferon-γ (IFN-γ) release assays still needs to be improved. The data on the performance of QuantiFERON-TB Gold Plus (QFT-Plus), a new-generation of QFT assay are limited. This study evaluated the diagnostic performance of QFT-Plus, and compared to that of QuantiFERON-TB Gold In-Tube (QFT-GIT). Blood samples were collected from 162 bacteriologically confirmed tuberculosis (TB) patients and 212 Mycobacterium tuberculosis-uninfected volunteers; these samples were then tested with QFT-GIT and QFT-Plus. The IFN-γ concentration of QFT-Plus was lower than that of QFT-GIT in TB patients (p Plus. Both assays showed area under the curve values over 0.99 without significant difference. Using the conventional cut-off (0.35 IU/mL) for QFT-GIT, QFT-Plus had a lower sensitivity of 91.1% compared to 96.2% (p = 0.008) at its optimum cut-off (0.168 IU/mL) with the same specificity. Moreover, IFN-γ values were significantly reduced with age in QFT-GIT (p = 0.035) but not in QFT-Plus. The diagnostic performance of QFT-Plus was as accurate as that of QFT-GIT despite a lack of TB7.7 antigen and despite the decrease in quantitative values. However, the cut-off value for QFT-Plus should be considered independently from that of QFT-GIT to obtain the best sensitivity without compromising specificity.

  14. Highly effective and inexpensive parasitological technique for diagnosis of intestinal parasites in developing countries: spontaneous sedimentation technique in tube.

    Science.gov (United States)

    Tello, Raúl; Terashima, Angélica; Marcos, Luis A; Machicado, Jorge; Canales, Marco; Gotuzzo, Eduardo

    2012-06-01

    Millions of low-income people in the world are affected by intestinal parasites. Inexpensive, simple, and effective techniques for diagnosis are necessary. The spontaneous sedimentation technique in tube (SSTT), for application in poor healthcare settings and under field-work conditions, was described 25 years ago in Peru by Tello. The advantages of the SSTT are its ability to detect the majority of intestinal parasites, including eggs, larvae, cysts, and trophozoites, and its low cost.

  15. Tube-in-tube reactor as a useful tool for homo- and heterogeneous olefin metathesis under continuous flow mode.

    Science.gov (United States)

    Skowerski, Krzysztof; Czarnocki, Stefan J; Knapkiewicz, Paweł

    2014-02-01

    A tube-in-tube reactor was successfully applied in homo- and heterogeneous olefin metathesis reactions under continuous flow mode. It was shown that the efficient removal of ethylene facilitated by connection of the reactor with a vacuum pump significantly improves the outcome of metathesis reactions. The beneficial aspects of this approach are most apparent in reactions performed at low concentration, such as macrocyclization reactions. The established system allows achievement of both improved yield and selectivity, and is ideal for industrial applications.

  16. Dependence of In-Tube Carbon Chain on the Radius and Helicity of Single-Wall Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    刘红; 董锦明; 万贤纲

    2002-01-01

    Using the Lennard-Jones interaction potential, we have studied the in-tube carbon-chain structure doped into single-wall carbon nanotubes (SWCNTs). Through minimizing the potential energy of the doped system, it is found that the optimal structure of the doping carbon chain is spiral, but not a straight line, when the radius of the SWCNT is larger than about 4.30A.

  17. Interface Characteristics Between Colloidal Gold and Kaolinite Surface by XPS

    Institute of Scientific and Technical Information of China (English)

    HONG Hanlie; TIE Liyun; BIAN Qiujuan; ZHOU Yong

    2006-01-01

    The distribution of gold colloids in kaolinite and the interaction between gold and kaolinite surface were investigated by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). There is strong interaction between the gold particles and the edge surfaces of kaolinite,in low pH solution,the edge surface of kaolinite is positively charged and electrostatic attractive force between colloide gold particles and the positive edge surface of kaolinite would facilitate the adsorption of colloidal gold particles onto the suface. TEM observation shows that the aggregate morphology of gold particles was dominated by particle-particle interaction and gold particles were adsorbed on the edge surface of kaolinite crystals, resulting from the electrostatic attractive force between colloidal gold particles and the positive surfaces of kaolinite. XPS data show that in Au4f electron spectra there are four energy peaks related to gold, 83.8 eV, 85.7 eV, 87.5 eV, and 89.4 eV, respectively, which suggests that in chemical states there are metallic gold and Au bonded to O, similar to the form of Au2O3, and composite Au2O3 is formed between the edge surface of kaolinite and colloidal gold surface.

  18. Biosorption and recycling of gold using various microorganisms.

    Science.gov (United States)

    Tsuruta, Takehiko

    2004-08-01

    In order to obtain basic information on the biosorption and recycling of gold from aqueous systems using microbial cells, the biosorption of gold by various microorganisms was investigated. Of 75 strains of microorganisms tested (25 bacteria, 19 actinomycetes, 17 fungi and 14 yeasts), high abilities of gold biosorption from a solution containing hydrogen tetrachloroaurate (III) were found in some gram-negative bacterial strains, such as Acinetobacter calcoaceticus, Erwinia herbicola, Pseudomonas aeruginosa, and P. maltophilia. Most of the gram-positive bacteria, actinomycetes, fungi and yeasts had a lower ability for gold biosorption than gram-negative bacteria. On the other hand, all of the microorganisms tested adsorbed far smaller amounts of gold from a solution containing gold dicyanoaurate (I). The biosorption of gold from a solution containing hydrogen tetrachloroaurate (III) using P. maltophilia having a high adsorbing ability for gold was very rapid and was affected by the pH of the solution, external gold concentration, and cell amounts. P. maltophilia cells immobilized with polyacrylamide gel also have a high ability for gold biosorption. The gold adsorbed on the immobilized cells is easily desorbed with 0.1 M thiourea solution. The immobilized P. maltophilia cells can be used repeatedly in biosorption-desorption cycles.

  19. Physicochemical Properties of Gold Nanostructures Deposited on Glass

    Directory of Open Access Journals (Sweden)

    Zdenka Novotna

    2014-01-01

    Full Text Available Properties of gold films sputtered onto borosilicate glass substrate were studied. UV-Vis absorption spectra were used to investigate optical parameters. XRD analysis provided information about the gold crystalline nanostructure, the texture, and lattice parameter and biaxial tension was also determined by the XRD method. The surface morphology was examined by atomic force microscopy (AFM; chemical structure of sputtered gold nanostructures was examined by X-ray photoelectron spectroscopy (ARXPS. The gold crystallites are preferentially [111] oriented on the sputtered samples. Gold deposition leads to dramatic changes in the surface morphology in comparison to pristine glass substrate. Oxygen is not incorporated into the gold layer during gold deposition. Experimental data on lattice parameter were also confirmed by theoretical investigations of nanoclusters using tight-binding potentials.

  20. Gold Nanoparticle-Biological Molecule Interactions and Catalysis

    Directory of Open Access Journals (Sweden)

    Jonathan G. Heddle

    2013-09-01

    Full Text Available This review gives a brief summary of the field of gold nanoparticle interactions with biological molecules, particularly those with possible catalytic relevance. Gold nanoparticles are well known as catalysts in organic chemistry but much is unknown regarding their potential as catalysts of reactions involving biological molecules such as protein and nucleic acids. Biological molecules may be the substrate for catalysis or, if they are the ligand coating the gold particle, may be the catalyst itself. In other cases biological molecules may form a template upon which gold nanoparticles can be precisely arrayed. As relatively little is currently known about the catalytic capabilities of gold nanoparticles in this area, this review will consider templating in general (including, but not restricted to, those which result in structures having potential as catalysts before going on to consider firstly catalysis by the gold nanoparticle itself followed by catalysis by ligands attached to gold nanoparticles, all considered with a focus on biological molecules.

  1. Rheumatoid arthritis, gold therapy, contact allergy and blood cytokines

    Directory of Open Access Journals (Sweden)

    Theander Jan

    2002-02-01

    Full Text Available Abstract Objective To study the clinical and biochemical effects of a low starting dose for gold therapy in rheumatoid arthritis patients with a contact allergy to gold. Methods Serum cytokines were assayed before and 24 h after the first injection of gold sodium thiomalate (GSTM. Results Contact allergy to gold was found in 4 of 19 patients. Compared to gold-negative patients (starting dose: 10 mg GSTM, there was a larger increase in serum TNFalpha (p Conclusions Cytokines are released in blood by GSTM in RA patients with gold allergy. To minimize the risk of acute adverse reactions the starting dose of GSTM should be lowered to 5 mg. Alternatively, patients should be patch-tested before gold therapy; in test-positive cases, 5 mg is recommended as the first dose.

  2. Preparation and characterization of gold-decorated graphite nanosheet composites.

    Science.gov (United States)

    Kim, Jungsoo; Nam, Dae Geun; Oh, Weon Tae

    2013-05-01

    Some composites of gold nanoparticles and graphite nanosheets were prepared by electrostatic interaction, and structurally and electrochemically characterized using X-ray diffraction, X-ray photoelectron spectroscopy, UVNis spectroscopy, transmission electron microscopy, and cyclic-voltammetry. Pristine graphite was chemically treated using aqueous acid solution, and dispersed inpoly(diallyldimethylammonium) chloride aqueous solution to prepare positively charged graphite nanosheets. The gold nanoparticles (GNPs) in this work were stabilized by sodium dodecyl sulfate, poly(sodium 4-styrene sulfonate), or poly(vinylpyrrolidone). Gold nanoparticles and graphite nanosheet composites with gold nanoparticles showed the characteristic surface plasmon band at -530 nm. The electrochemical properties of the graphite nanosheet composites with gold nanoparticles were studied by cyclic voltammetry, in which reduction potential and reduction current of gold nanoparticles were strongly dependent on the gold-wrapped stabilizer in the composites.

  3. The use of gold nanoparticles to enhance radiotherapy in mice

    Energy Technology Data Exchange (ETDEWEB)

    Hainfeld, James F [Nanoprobes, Inc., 95 Horse Block Rd., Yaphank, NY 11980 (United States); Slatkin, Daniel N [Nanoprobes, Inc., 95 Horse Block Rd., Yaphank, NY 11980 (United States); Smilowitz, Henry M [Department of Pharmacology, University of Connecticut Health Center, 263 Farmington Ave., Farmington, CT 06030 (United States)

    2004-09-21

    Mice bearing subcutaneous EMT-6 mammary carcinomas received a single intravenous injection of 1.9 nm diameter gold particles (up to 2.7 g Au/kg body weight), which elevated concentrations of gold to 7 mg Au/g in tumours. Tumour-to-normal-tissue gold concentration ratios remained {approx}8:1 during several minutes of 250 kVp x-ray therapy. One-year survival was 86% versus 20% with x-rays alone and 0% with gold alone. The increase in tumours safely ablated was dependent on the amount of gold injected. The gold nanoparticles were apparently non-toxic to mice and were largely cleared from the body through the kidneys. This novel use of small gold nanoparticles permitted achievement of the high metal content in tumours necessary for significant high-Z radioenhancement. (note)

  4. The use of gold nanoparticles to enhance radiotherapy in mice.

    Science.gov (United States)

    Hainfeld, James F; Slatkin, Daniel N; Smilowitz, Henry M

    2004-09-21

    Mice bearing subcutaneous EMT-6 mammary carcinomas received a single intravenous injection of 1.9 nm diameter gold particles (up to 2.7 g Au/kg body weight), which elevated concentrations of gold to 7 mg Au/g in tumours. Tumour-to-normal-tissue gold concentration ratios remained approximately 8:1 during several minutes of 250 kVp x-ray therapy. One-year survival was 86% versus 20% with x-rays alone and 0% with gold alone. The increase in tumours safely ablated was dependent on the amount of gold injected. The gold nanoparticles were apparently non-toxic to mice and were largely cleared from the body through the kidneys. This novel use of small gold nanoparticles permitted achievement of the high metal content in tumours necessary for significant high-Z radioenhancement.

  5. Use of ferricyanide for gold and silver cyanidation

    Institute of Scientific and Technical Information of China (English)

    F. XIE; D. B. DREISINGER

    2009-01-01

    Low gold and silver leaching kinetics has been commonly observed in traditional gold-silver cyanidation process, especially in heap leaching and in situ leaching operations. The different mineralogy of gold and silver in the ores is suspected to be the main reason, e.g., the occurrence of low solubility acanthite (Ag2S) typically results in low overall silver extraction. Due to the low solubility of oxygen in cyanide solution, the reactivity and availability of oxidant is believed to be the critical limitation for gold and silver dissolution. The use of ferricyanide as the auxiliary oxidant for gold and silver cyanidation has been examined. The rotating disc test results prove the assistant effect of ferricyanide on increasing the dissolution rate of gold and silver. The potential use of ferricyanide in gold/silver cyanidation process is proposed based on the leaching results of actual ores.

  6. Chirality in thiolate-protected gold clusters.

    Science.gov (United States)

    Knoppe, Stefan; Bürgi, Thomas

    2014-04-15

    Over recent years, research on thiolate-protected gold clusters Au(m)(SR)n has gained significant interest. Milestones were the successful determination of a series of crystal structures (Au102(SR)44, Au25(SR)18, Au38(SR)24, Au36(SR)24, and Au28(SR)20). For Au102(SR)44, Au38(SR)24, and Au28(SR)20, intrinsic chirality was found. Strong Cotton effects (circular dichroism, CD) of gold clusters protected by chiral ligands have been reported a long time ago, indicating the transfer of chiral information from the ligand into the cluster core. Our lab has done extensive studies on chiral thiolate-protected gold clusters, including those protected with chiral ligands. We demonstrated that vibrational circular dichroism can serve as a useful tool for the determination of conformation of the ligand on the surface of the cluster. The first reports on crystal structures of Au102(SR)44 and Au38(SR)24 revealed the intrinsic chirality of these clusters. Their chirality mainly arises from the arrangement of the ligands on the surface of the cluster cores. As achiral ligands are used to stabilize the clusters, racemic mixtures are obtained. However, the separation of the enantiomers by HPLC was demonstrated which enabled the measurement of their CD spectra. Thermally induced inversion allows determination of the activation parameters for their racemization. The inversion demonstrates that the gold-thiolate interface is anything but fixed; in contrast, it is rather flexible. This result is of fundamental interest and needs to be considered in future applications. A second line of our research is the selective introduction of chiral, bidentate ligands into the ligand layer of intrinsically chiral gold clusters. The ligand exchange reaction is highly diastereoselective. The bidentate ligand connects two of the protecting units on the cluster surface and thus effectively stabilizes the cluster against thermally induced inversion. A minor (but significant) influence of chiral ligands to

  7. Antifungal activity of gold nanoparticles prepared by solvothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Manzoor, Nikhat; Ahmad, Aijaz [Department of Biosciences, Jamia Millia Islamia, New Delhi 110025 (India); Ahmed, Jahangeer [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Al-Shihri, Ayed S. [Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004 (Saudi Arabia)

    2013-01-15

    Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m{sup 2}/g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m{sup 2/}g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl{sub 2} and NaBH{sub 4} as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl{sub 2}, however, NaBH{sub 4} produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m{sup 2}/g for 7 nm and 269 m{sup 2}/g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H{sup +} efflux of the Candida species than 15 nm sized gold nanoparticles.

  8. World-class Xincheng gold deposit:An example from the giant Jiaodong gold province

    Institute of Scientific and Technical Information of China (English)

    Liqiang Yang; Jun Deng; Ruipeng Guo; Lin’nan Guo; Zhongliang Wang; Binghan Chen; Xudong Wang

    2016-01-01

    The Jiaodong gold deposits are currently the most important gold resources (with Au reserves of>4000 t) in China, and the leading gold-producing country globally (with Au production of w428 t in 2013). Jiaodong is also considered as perhaps the only world-class to giant gold accumulation on the planet where relatively young gold ores (ca. 130e120 Ma) were deposited in rocks that are 2 Ga older. The Xincheng world-class high-grade gold deposit, with a proven reserve of >200 t gold, is one of the largest deposits in the giant gold province of the Jiaodong Peninsula. It is located in the northwestern part of the Jiaobei Uplift, and hosted by ca. 132e123 Ma Xincheng quartz monzonites and monzogranites. Ore zones are structurally controlled by the NE-trending and NW-dipping Jiaojia Fault and subsidiary faults, and are mainly restricted to the footwall of the fault. The dominant disseminated-and stockwork-style ores are associated with strong sericitization, silicification, sulfidation and K-feldspathization, and minor carbonate wallrock alteration halos. The four mineralization stages are pyriteequartzesericite (stage 1), quartzepyrite (stage 2), quartzepolysulfide (stage 3) and quartzecarbonate (stage 4). Gold occurs dominantly as electrum, with lesser amounts of sulfide-hosted native gold and rare native silver and argentite, normally associated with pyrite, chalcopyrite, galena and sphalerite:the latter with proven resources of about 105 t Ag, 713 t Cu, and 5100 t S. There are three types of ore-related fluid inclusions: type 1 aqueous-carbonate (H2OeCO2), type 2 aqueous (liquid H2O þ vapor H2O), and type 3 CO2 (liquid CO2 and vapor CO2) inclusions. Homogeni-zation temperatures range from 221 to 304 ?C for type 1 inclusions, with salinities of 2.4e13.3 wt.%NaCl eq., and bulk densities of 0.858e1.022 g/cm3. The d34SCDT values of hydrothermal sulfides are 4.3e10.6&and d18O values of hydrothermal quartz have a median value of 13.0&. dD values of fluid inclusions in

  9. Ore—Search Perspective for Superlarge Gold Deposits in the Jiaolai Basin of the Jiaodong Gold Metallogenetic Domain

    Institute of Scientific and Technical Information of China (English)

    张竹如; 陈世桢; 等

    2000-01-01

    There are three types of gold deposits in the Jiaodong gold metallogenetic domain.The strata-bound gold deposits are a new type,which occur in a hydrocarbon-dled double-source bed enriched in gold(Au 174ng/g) and organic carbon(0.007-4.225%),At diagenetic a d hydrotherrmal stages water and oil were simultaneously activated and the stratabound gold deposits were formed from interactions between water ,oil and rocks.In the late Yanshanian period,gold oreboides were enriched and enlarged in response to tectonmoagmatism and action of complex ore-forming hydrothermal solutions.As a results,it is highly expected to find suparlarge gold deposits and the Yanzi area is expected to be a perspective target area.

  10. Origin of Gold-Bearing Fluid and Its Initiative Localization Mechanism in Xiadian Gold Deposit, Shandong Province

    Institute of Scientific and Technical Information of China (English)

    邓军; 王庆飞; 孙忠实

    2002-01-01

    The composition of quartz inclusions and trace elements in ore indicate that gold bearing fluid in the Xiadian gold deposit, Shandong Province, stemmed from both mantle and magma, belonging to a composite origin. Based on theoretical analysis and high temperature and high pressure experimental studies, gold-bearing fluid initiative localization mechanism and the forming environment of ore-host rocks are discussed in the present paper. The composite fluid extracted gold from rocks because of its expanding and injecting forces and flew through ore-conducive structures, leading to the breakup of rocks. The generation of ore-host faults and the precipitation of gold-bearing fluid occurred almost simultaneously. This study provides further information about the relationships between gold ore veins and basic-ultrabasic vein rocks and intermediate vein rocks, the spatial distribution of gold ore veins and the rules governing the migration of ore fluids.

  11. Laizhou to Build the World’s Largest Gold Industrial Base

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>Shandong Gold Group will invest RMB 35 billion to build a gold industrial base in Laizhou and gear up its 9 major gold industrial chain projects. The group’s gold output value is expected to top RMB 50 billion and reach RMB 100 billion by 2015.Laizhou boasts abundant gold reserves,and is China’s gold mining & dressing and refining base with the highest industrial concentration and the greatest scale. In June 2012,Shandong Gold Group and Laizhou

  12. Gold in erythrocytes, whole blood, and plasma during long-term chrysotherapy.

    OpenAIRE

    Pedersen, S.M.; Graabaek, P M

    1980-01-01

    The concentrations of gold in erythrocytes, whole blood, cell-rich plasma, and cell-free plasma were investigated in 17 patients with rheumatoid arthritis undergoing long-term chrysotherapy. Gold estimations were performed with a graphite tube atomic absorption spectrophotometer. Significant quantities of gold were found in isolated erythrocytes of 12 patients. There was no correlation between erythrocyte gold and therapeutic response, plasma gold, and gold in whole blood. Nor did gold in who...

  13. Ultraviolet imaging detectors for the GOLD mission

    Science.gov (United States)

    Siegmund, O. H. W.; McPhate, J.; Curtis, T.; Jelinsky, S.; Vallerga, J. V.; Hull, J.; Tedesco, J.

    2016-07-01

    The GOLD mission is a NASA Explorer class ultraviolet Earth observing spectroscopy instrument that will be flown on a telecommunications satellite in geostationary orbit in 2018. Microchannel plate detectors operating in the 132 nm to 162 nm FUV bandpass with 2D imaging cross delay line readouts and electronics have been built for each of the two spectrometer channels for GOLD. The detectors are "open face" with CsI photocathodes, providing 30% efficiency at 130.4 nm and 15% efficiency at 160.8 nm. These detectors with their position encoding electronics provide 600 x 500 FWHM resolution elements and are photon counting, with event handling rates of > 200 KHz. The operational details of the detectors and their performance are discussed.

  14. Tamper indicating gold nanocup plasmonic films

    Energy Technology Data Exchange (ETDEWEB)

    DeVetter, Brent M.; Bernacki, Bruce E.; Bennett, Wendy D.; Schemer-Kohrn, Alan; Alvine, Kyle J.

    2017-02-13

    The spectral signature of nanoplasmonic films are both robust and tailorable with optical responses ranging from the visible to the near-infrared. We present the development of flexible, elastomeric nanoplasmonic films consisting of periodic arrays of gold nanocups as tamper indicating films. Gold nanocups have polarization-sensitive optical properties that may be manufactured into films that offer unique advantages for tamper indication. These flexible films can be made quickly and at low-cost using commercially available monodisperse polystyrene nanospheres through self-assembly followed by plasma etching, metal deposition, and lift-off from a sacrificial substrate. Polarization- and angle-dependent optical spectroscopic measurements were performed to characterize the fabricated films. Using polarization-sensitive hyperspectral imaging, we demonstrate how these films can be applied to tamper indication and counterfeit resistance applications.

  15. Reversible peptide oligomerization over nanoscale gold surfaces

    Directory of Open Access Journals (Sweden)

    Kazushige Yokoyama

    2015-11-01

    Full Text Available A selective oligomeric formation of amyloid beta 1-40 (Ab1-40 monomers over a nanogold colloidal surface was investigated. An unfolded Ab1-40 monomer is considered to construct a dimer or trimer based oligomeric form with its hydrophobic segment placing outward under an acidic condition. Under a basic condition, a conformation of Ab is expected to take a folded monomeric form with its hydrophilic segment folded inward, avoiding the networking with residual colloidal particles. The most probable oligomeric form constructed over a 20 nm gold colloidal surface within a 25 ℃ to 65 ℃ temperature range is a dimer based unit and that over 30 or 40 nm gold colloidal surface below 15 ℃ is concluded to be a trimer based unit. However, selective oligomerization was not successfully reproduced under the rest of the conditions. A dipole-induced dipole interaction must cause a flexible structural change between folded and unfolded forms.

  16. Gold resource modeling using pod indicator kriging

    Science.gov (United States)

    Bargawa, Waterman Sulistyana; Rauf, Abdul; Amri, Nur Ali

    2016-02-01

    This paper describes an implementation of the pod indicator kriging method used to gold resource modeling. Method such as ordinary kriging estimate the mean grade of a block that is fairly large. The usual outcome is that large blocks rarely turn out to be all ore or all waste, thus making reserve estimates an incorrect estimate of what will be mined. Pod indicator kriging offers a solution to this problem by estimating the distribution of grade values within a large block, rather than just estimating the mean grade of the block. Knowing the distribution of grade value within the block, it is then easy to calculate the proportion of the block that is above cutoff grade and the grade of the ore above cutoff grade. This research shows that the pod indicator kriging model is quite applicable and reliable in gold resourcemodeling.

  17. GOLD NANOPARTICLES: PROMISING AND POTENTIAL NANOMATERIAL

    Directory of Open Access Journals (Sweden)

    Madhuri Shringirishi*, S.K. Prajapati , Alok Mahor , Shashi Alok , Poonam Yadav and Amita Verma

    2013-11-01

    Full Text Available Gold nanoparticles (AuNPs have appeared as an attractive candidate for delivery of various drug molecules or considered as extraordinary molecular carriers for the targeting, intracellular trafficking and delivery of a huge array of biomolecules including DNA, RNA, proteins, peptides, drugs, genes and other molecules of therapeutic significance. Particularly gold nanoparticles have attracted intensive interest, because they are easily prepared, have low toxicity and can be readily attached to molecules of biological interest. More and more research shows that AuNPs-based technologies are becoming promising approaches in drug and gene delivery, liver targeting, brain targeting, cancer research and AIDS treatment. The present review focuses on synthesis and functionalization methods of GNPs, the past researchs and reviews about GNPs, their emerging applications and uses and their future prospects.

  18. Gold nanodisk array surface plasmon resonance sensor

    Science.gov (United States)

    Tian, Xueli

    Surface plasmon resonances in periodic metal nanostructures have been investigated for sensing applications over the last decade. The resonance wavelengths of the nanostructures are usually measured in the transmission or reflection spectrum for chemical and biological sensing. In this thesis, I introduce a nanoscale gap mediated surface plasmon resonance nanodisk array for displacement sensing and a super-period gold nanodisk grating enabled surface plasmon resonance spectrometer sensor. The super-period gold nanodisk grating has a small subwavelength period and a large diffraction grating period. Surface plasmon resonance spectra are measured in the first order diffraction spatial profiles captured by a charge-coupled device (CCD). A surface plasmon resonance sensor for the bovine serum albumin (BSA) protein nanolayer bonding is demonstrated by measuring the surface plasmon resonance shift in the first order diffraction spatial intensity profiles captured by the CCD.

  19. Ordered arrays of nanoporous gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Dong Wang

    2012-09-01

    Full Text Available A combination of a “top-down” approach (substrate-conformal imprint lithography and two “bottom-up” approaches (dewetting and dealloying enables fabrication of perfectly ordered 2-dimensional arrays of nanoporous gold nanoparticles. The dewetting of Au/Ag bilayers on the periodically prepatterned substrates leads to the interdiffusion of Au and Ag and the formation of an array of Au–Ag alloy nanoparticles. The array of alloy nanoparticles is transformed into an array of nanoporous gold nanoparticles by a following dealloying step. Large areas of this new type of material arrangement can be realized with this technique. In addition, this technique allows for the control of particle size, particle spacing, and ligament size (or pore size by varying the period of the structure, total metal layer thickness, and the thickness ratio of the as-deposited bilayers.

  20. Interconnecting Gold Islands with DNA Origami Nanotubes

    Science.gov (United States)

    Ding, Baoquan; Wu, Hao; Xu, Wei; Zhao, Zhao; Liu, Yan; Yu, Hongbin; Yan, Hao

    2012-01-01

    Scaffolded DNA origami has recently emerged as a versatile, programmable method to fold DNA into arbitrarily shaped nanostructures that are spatially addressable, with sub-10 nm resolution. Toward functional DNA nanotechnology, one of the key challenges is to integrate the bottom up self-assembly of DNA origami with the top-down lithographic methods used to generate surface patterning. In this report we demonstrate that fixed length DNA origami nanotubes, modified with multiple thiol groups near both ends, can be used to connect surface patterned gold islands (tens of nanometers in diameter) fabricated by electron beam lithography (EBL). Atomic force microscopic imaging verified that the DNA origami nanotubes can be efficiently aligned between gold islands with various inter-island distances and relative locations. This development represents progress toward the goal of bridging bottom up and top down assembly approaches. PMID:21070012

  1. Light scattering of interacting gold nanorods

    Energy Technology Data Exchange (ETDEWEB)

    McGuirt, Baxter; Kielbasa, Jerry; Park, Jung-Ho; Zhang, Junping; Peterson, Eric; Williams, Richard; Carroll, David [Center for Nanotechnology and Molecular Materials and Department of Physics, Wake Forest University, Winston-Salem, NC (United States); Sisco, Patrick; Murphy, Catherine; Adams, Richard D. [Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC (United States)

    2009-12-15

    The optical field intensity of light scattering from nanorods of gold has been imaged at distances that are intermediate between the near-field and far-field regimes using a near-field scanning optical microscope (NSOM). For scattering from isolated nanorods the Fraunhofer diffractive behaviour is modified slightly by the dipolar nature of metal nanoantannae as would be expected at these imaging distances. However, when the nanorods are brought into close proximity, interactions between the nanorods alter the scattering behaviour substantially creating large field intensities between the structures. By sampling the field with the near-field microscope tip scanned at different heights, detailed maps of the scattering profile can be generated. The NSOM image of far-field scattered light from an isolated gold nanorod. The nanorod was imaged at a distance of roughly 8 {mu}m above the support substrate using a scanning near-field microscope operated at constant height mode. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  2. Structural and plasmonic properties of gold nanocrystals

    Science.gov (United States)

    Sivapalan, Sean T.

    The design of gold nanoparticles for surface-enhanced Raman scattering (SERS) and plasmonic enhanced fluorescence are more involved than simply maximizing the local field enhancement. The enhancement is a function of the excitation wavelength relative to the plasmon resonance as well as the distance of the reporter molecules from the nanoparticles' surface. For suspension based measurements, additional considerations must also be made regarding absorption and scattering effects as light propagates through the sample. These effects are in addition to the other more commonly observed effects such as nanocrystal shape. With such a wide number of variables in play, a series of studies breaking down each of these components and their contribution to the observed enhancement is warranted. In this thesis, a series of experiments were undertaken using a platform based on polyelectrolyte coating of gold nanoparticles by layer-by-layer deposition. The reporter molecules are bound onto the surface of polyelectrolyte coated nanoparticles before trap coating them with an additional oppositely charged polyelectrolyte layer. By etching away the gold nanoparticle using potassium cyanide, we are then able to quantify the number of reporter molecule per nanoparticle using mass spectrometry. With this quantitative approach, we can the directly compare the effects of the aforementioned enhancement mechanisms on the observed signal intensity. This method overcomes some of the disparities in literature between reported values of enhancement due to assumption in the number of reporter molecules contribution to the signal intensity. Using our group's expertise, we synthesized gold nanoparticle libraries of nanorods, cubes, trisoctahedra and spheres of different sizes. Each geometric configuration was characterized using a recently developed TEM technique---nano-beam coherent area diffraction. The as-synthesized were exposed to a coherent electron beam with probe size similar to that of

  3. Tamper indicating gold nanocup plasmonic films

    Science.gov (United States)

    DeVetter, Brent M.; Bernacki, Bruce E.; Bennett, Wendy D.; Schemer-Kohrn, Alan; Alvine, Kyle J.

    2017-02-01

    The spectral signatures of nanoplasmonic films are both robust and tailorable with optical responses ranging from the visible to the near-infrared. We present the development of flexible, elastomeric nanoplasmonic films consisting of periodic arrays of gold nanocups as tamper indicating films. Gold nanocups have polarization-sensitive optical properties that may be manufactured into films that offer unique advantages for tamper indication. These flexible films can be made quickly and at low-cost using the commercially available monodisperse polystyrene nanospheres through self-assembly followed by plasma etching, metal deposition, and lift-off from a sacrificial substrate. The polarization- and angle-dependent optical spectroscopic measurements were performed to characterize the fabricated films. Using polarization-sensitive hyperspectral imaging, we demonstrate how these films can be applied to tamper indication and counterfeit resistance applications.

  4. A New Genetic Type of Gold Deposits-Meso-Epithermal Carbonate-Type Gold Deposits as Exemplified by the Baguamiao Suprlarge Gold Deposit

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    Gold deposits of the meso-epithermal carbonate type were first proposed based on the study of the Baguamiao gold deposit.This new type of gold deposits has many unique characteristics as follows:(1)Obviously strata-bound.The gold deposits are hosted in Middle Devonian turbidite formations;(2)Structrually controlled.Struc-ture is an important factor leading to metallogenesis of this type of gold deposits.The shape and distribution of orebodies are controlled by byittle-ductile shear zones;(3)Multi-stage wall-rock alteration.According to the characteristics of mineral assemblage,gold mineralization can be classified into three stages in association with various wall-rock al-terations.Wall-rock alterations closely genetically related to the gold mineralization are ankerization ,silicification,pyrrhotization and pyritization ;(4)Mineral compositions of the orebodies are mainly pyrrhotite,pyrite,marcasitolite,chalcopyrite,quartz,ankerite,and sericite.Gold mineralization is associated closely in space and time with iron sulfides;(5)Rare elements and REE in ores are low in contents relative to those of the crust.Au content varies from 1.91g/t to 11.15g/t ,averaging 5.5g/t;(6)Studies of sulfur,hydrogen,oxygen and carbon isotopes in main gangue minerals (quartz and ankerite)indicate that fluids and ore-forming materials came from deep-seated sources;(7)Three types of inclusions are recognized in terms of their composition and the vapor amounts of inclusions.The homogenization temperatures of inclusions range from 210℃to 310℃,averaging 230℃,showing that this type of gold deposits belongs to the meso-epithermal type;(8)Metallogenic age of this type of gold deposits is similar to that of the collision between the Yangtze Plate and the North China Plate,indicating that gold deposits of this type are genetically related to continental-margin plate activity.

  5. NA35: sulphur-gold collision

    CERN Multimedia

    1991-01-01

    In this image the real particles produced by the collision of a 6400 GeV sulphur ion with a gold target can be seen as they pass through a streamer chamber. Streamer chambers consist of a gas chamber through which a strong pulsed electric field is passed, creating sparks as a charged particle passes through it. The NA35 experiment, which was in operation in the 1980s, was part of CERN's ongoing heavy ion project.

  6. Microbial biosynthesis of nontoxic gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Swarup, E-mail: swaruproy@klyuniv.ac.in [Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal (India); Das, Tapan Kumar [Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal (India); Maiti, Guru Prasad [Department of Molecular Biology and Biotechnology, University of Kalyani, Kalyani 741235, West Bengal (India); Department of Anesthesiology, Texas Tech University Health science Center, 3601 4th Street, Lubbock, TX 79430 (United States); Basu, Utpal [Department of Molecular Biology and Biotechnology, University of Kalyani, Kalyani 741235, West Bengal (India)

    2016-01-15

    Graphical abstract: The manuscript deals with the fungus mediated optimized biologically synthesized GNPs using Aspergillus foetidus and characterization of biosynthesized GNPs using various physico-chemical methods. The fairly stable synthesized nanoparticles have size in the range of 10–40 nm. Cytotoxicity study of biosynthesized GNPs on Human lung cancer cell line A549 showed no significant toxicity of GNPs. - Highlights: • A novel biosynthesis process of GNPs using Aspergillus foetidus. • Biosynthesized GNPs are in the range of 10–40 nm as observed from TEM. • This process of synthesis is an optimized biosynthesis process of GNPs. • Biosynthesized GNPs are noncytotoxic against A549 cell line. - Abstract: We study the extracellular biosynthesis of gold nanoparticles (GNPs) using the fungal species Aspergillus foetidus. The formation of GNPs were initially monitored by visual observation and then characterized with the help of various characterization techniques. X-ray diffraction (XRD) results revealed distinctive formation of face centered cubic crystalline GNPs. From field emission scanning electron microscopy (FESEM) the morphology of the nanoparticles were found to be roughly spherical and within the size range of 30–50 nm. The spherical and polydispersed GNPs in the range of 10–40 nm were observed by transmission electron microscopy (TEM) analysis. It was established that alkaline pH, 1 mM gold salt concentration and 75 °C temperature were the respective optimum parameter for biosynthesis of GNPs. Cell cytotoxicity of GNP was compared with that of normal gold salt solution on A549 cell. The A549 cell growth in presence of GNPs was found to be comparatively less toxic than the gold ion.

  7. Broadband Spectroscopy of Nanoporous-Gold Promoter

    Directory of Open Access Journals (Sweden)

    S. K. Nakatani

    2014-02-01

    Full Text Available The efficiency of UV photocatalysis on TiO2 particles was increased by mixing TiO2 particles with nanoporous gold (NPG with pore diameters of 10–40 nm. This means that NPG acts as a promoter in the photocatalytic reaction of TiO2. Broadband spectroscopic results from millimeter wave to ultra violet of NPG membrane are discussed to estimate plasmonic effect on the catalysis.

  8. Alternative Plasmonic Materials: Beyond Gold and Silver

    DEFF Research Database (Denmark)

    Naik, Gururaj V.; Shalaev, Vladimir M.; Boltasseva, Alexandra

    2013-01-01

    such as gold and silver, that exhibit metallic properties and provide advantages in device performance, design flexibility, fabrication, integration, and tunability. This review explores different material classes for plasmonic and metamaterial applications, such as conventional semiconductors, transparent...... in plasmonics and metamaterials lacks good material building blocks in order to realize useful devices. Such devices suffer from many drawbacks arising from the undesirable properties of their material building blocks, especially metals. There are many materials, other than conventional metallic components...

  9. Attachment of Gold Nanoparticles to Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Xi Cheng MA; Ning LUN; Shu Lin WEN

    2005-01-01

    Carbon nanotubes were initially chemically modified with an H2SO4-HNO3 treatment,and subsequently activated with Pd-Sn catalytic nuclei via a one-step activation approach. These activated nanotubes were used as precursors for obtaining gold nanoparticles-attached nanotubes via simple electroless plating. This approach provides an efficient method for attachment of metal nanostructures to carbon nanotubes. Such novel hybrid nanostructures are attractive for many applications.

  10. Trapping atmospheric CO2 with gold.

    Science.gov (United States)

    Collado, Alba; Gómez-Suárez, Adrián; Webb, Paul B; Kruger, Hedi; Bühl, Michael; Cordes, David B; Slawin, Alexandra M Z; Nolan, Steven P

    2014-10-07

    The ability of gold-hydroxides to fix CO2 is reported. [Au(IPr)(OH)] and [{Au(IPr)}2(μ-OH)][BF4] react with atmospheric CO2 to form the trigold carbonate complex [{Au(IPr)}3(μ(3)-CO3)][BF4]. Reactivity studies revealed that this complex behaves as two basic and one cationic Au centres, and that it is catalytically active. DFT calculations and kinetic experiments have been carried out.

  11. Optical Trapping of Gold Nanoparticles in Air.

    Science.gov (United States)

    Jauffred, Liselotte; Taheri, S Mohammad-Reza; Schmitt, Regina; Linke, Heiner; Oddershede, Lene B

    2015-07-08

    Most progress on optical nanoparticle control has been in liquids, while optical control in air has proven more challenging. By utilizing an air chamber designed to have a minimum of turbulence and a single laser beam with a minimum of aberration, we trapped individual 200 to 80 nm gold nanoparticles in air and quantified the corresponding trapping strengths. These results pave the way for construction of metallic nanostructures in air away from surfaces.

  12. Optical Limiting Materials Based on Gold Nanoparticles

    Science.gov (United States)

    2014-04-30

    Murphy, University of Illinois at Urbana-Champaign (formerly University of South Carolina), Department of Chemistry Award Number: FA9550-09-1-0246...of the electromagnetic spectrum. 2. Functionalization of the surface of the gold nanoparticles with selected organic and inorganic materials, with...the thesis work of one Ph.D. student (Sean Sivapalan, Ph.D. in materials science and engineering, graduated in 2013, now employed at Intel

  13. Shape-Controlled Gold Nanoparticle Synthesis

    Science.gov (United States)

    2013-09-01

    prisms (5, 13–17), nanospheres (18, 19), and other platonic (20–22), branched (12), and anisotropic (12, 23, 24) morphologies. Although synthesis...polyol reaction method involving the use of poly(vinylpyrrolidone) as a reducing agent to produce various platonic Au nanoparticles. In a very...6786. 20. Kim, F.; Connor, S.; Song, H.; Kuykendall, T.; Yang, P. Platonic Gold Nanocrystals. Angewandte Chemie International Edition 2004, 43

  14. Comparative Aquatic Toxicity of Gold Nanoparticles and Ionic Gold Using a Species Sensitivity Distribution Approach

    Directory of Open Access Journals (Sweden)

    Tarryn L. Botha

    2015-01-01

    Full Text Available Gold nanoparticles (nAu are used in drug delivery systems allowing for targeted cellular distribution. The effects of increased use and release of nanoparticles into the environment are not well known. A species sensitivity distribution (SSD allows for the ecotoxicological hazard assessment of a chemical based on single species toxicity tests. Aquatic toxicity needs to be related to particle characterization in order to understand the effects. The behaviour of nAu in the medium changed as the concentration increased. The toxic potential of ionic gold and nAu was expressed as a hazardous concentration where 5% of species will be harmed (HC5. The HC5 for nAu was much higher (42.78 mg/L compared to the ionic gold (2.44 mg/L. The differences between the hazard potentials of nAu and ionic gold were attributed to the nAu not releasing any Au ions into solution during the exposures and following an aggregation theory response. Exposures to ionic gold on the other hand followed a clear dose dependent response based on the concentration of the ionic metal. Although SSDs present an indication of the relative hazard potential of nanoparticles, the true worth can only be achieved once other nanoparticle characteristics and their behavior in the environment are also considered.

  15. In Vivo Renal Clearance, Biodistribution, Toxicity of Gold nanoclusters

    CERN Document Server

    Zhang, Xiao-Dong; Shen, Xiu; Liu, Pei-Xun; Fan, Fei-Yue; Fan, Sai-Jun; 10.1016/j.biomaterials.2012.03.020

    2012-01-01

    Gold nanoparticles have shown great prospective in cancer diagnosis and therapy, but they can not be metabolized and prefer to accumulate in liver and spleen due to their large size. The gold nanoclusters with small size can penetrate kidney tissue and have promise to decrease in vivo toxicity by renal clearance. In this work, we explore the in vivo renal clearance, biodistribution, and toxicity responses of the BSA- and GSH-protected gold nanoclusters for 24 hours and 28 days. The BSA-protected gold nanoclusters have low-efficient renal clearance and only 1% of gold can be cleared, but the GSH-protected gold nanoclusters have high-efficient renal clearance and 36 % of gold can be cleared after 24 hours. The biodistribution further reveals that 94% of gold can be metabolized for the GSH-protected nanoclusters, but only less than 5% of gold can be metabolized for the BSA-protected nanoclusters after 28 days. Both of the GSH- and BSA-protected gold nanoclusters cause acute infection, inflammation, and kidney fu...

  16. Role of CO2 in the formation of gold deposits.

    Science.gov (United States)

    Phillips, G N; Evans, K A

    2004-06-24

    Much of global gold production has come from deposits with uneconomic concentrations of base metals, such as copper, lead and zinc. These 'gold-only' deposits are thought to have formed from hot, aqueous fluids rich in carbon dioxide, but only minor significance has been attached to the role of the CO2 in the process of gold transport. This is because chemical bonding between gold ions and CO2 species is not strong, and so it is unlikely that CO2 has a direct role in gold transport. An alternative indirect role for CO2 as a weak acid that buffers pH has also appeared unlikely, because previously inferred pH values for such gold-bearing fluids are variable. Here we show that such calculated pH values are unlikely to record conditions of gold transport, and propose that CO2 may play a critical role during gold transport by buffering the fluid in a pH range where elevated gold concentration can be maintained by complexation with reduced sulphur. Our conclusions, which are supported by geochemical modelling, may provide a platform for new gold exploration methods.

  17. Biosynthesis of gold nanoparticles: A green approach.

    Science.gov (United States)

    Ahmed, Shakeel; Annu; Ikram, Saiqa; Yudha S, Salprima

    2016-08-01

    Nanotechnology is an immensely developing field due to its extensive range of applications in different areas of technology and science. Different types of methods are employed for synthesis of nanoparticles due to their wide applications. The conventional chemical methods have certain limitations with them either in the form of chemical contaminations during their syntheses procedures or in later applications and use of higher energy. During the last decade research have been focussed on developing simple, clean, non-toxic, cost effective and eco-friendly protocols for synthesis of nanoparticles. In order to get this objective, biosynthesis methods have been developed in order to fill this gap. The biosynthesis of nanoparticles is simple, single step, eco-friendly and a green approach. The biochemical processes in biological agents reduce the dissolved metal ions into nano metals. The various biological agents like plant tissues, fungi, bacteria, etc. are used for biosynthesis for metal nanoparticles. In this review article, we summarised recent literature on biosynthesis of gold nanoparticles which have revolutionised technique of synthesis for their applications in different fields. Due to biocompatibility of gold nanoparticles, it has find its applications in biomedical applications. The protocol and mechanism of biosynthesis of gold nanoparticles along with various applications have also been discussed.

  18. Photoswitchable NIR-Emitting Gold Nanoparticles.

    Science.gov (United States)

    Bonacchi, Sara; Cantelli, Andrea; Battistelli, Giulia; Guidetti, Gloria; Calvaresi, Matteo; Manzi, Jeannette; Gabrielli, Luca; Ramadori, Federico; Gambarin, Alessandro; Mancin, Fabrizio; Montalti, Marco

    2016-09-05

    Photo-switching of the NIR emission of gold nanoparticles (GNP) upon photo-isomerization of azobenzene ligands, bound to the surface, is demonstrated. Photophysical results confirm the occurrence of an excitation energy transfer process from the ligands to the GNP that produces sensitized NIR emission. Because of this process, the excitation efficiency of the gold core, upon excitation of the ligands, is much higher for the trans form than for the cis one, and t→c photo-isomerization causes a relevant decrease of the GNP NIR emission. As a consequence, photo-isomerization can be monitored by ratiometric detection of the NIR emission upon dual excitation. The photo-isomerization process was followed in real-time through the simultaneous detection of absorbance and luminescence changes using a dedicated setup. Surprisingly, the photo-isomerization rate of the ligands, bound to the GNP surface, was the same as measured for the chromophores in solution. This outcome demonstrated that excitation energy transfer to gold assists photo-isomerization, rather than competing with it. These results pave the road to the development of new, NIR-emitting, stimuli-responsive nanomaterials for theranostics.

  19. Infrared optical properties of gold nanoantenna arrays

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Daniel; Neubrech, Frank; Pucci, Annemarie [Kirchhoff Institute for Physics, Heidelberg (Germany); Gui, Han; Enders, Dominik; Nagao, Tadaaki [National Institute for Materials Science, Tsukuba (Japan)

    2011-07-01

    Antenna-like gold nanoparticles are proven to be well-suited for spectroscopic applications due to their tuneable plasmonic properties. Excited resonantly by electromagnetic radiation, they are able to strongly enhance the local electromagnetic field. This effect can be exploited for example for surface-enhanced infrared (IR) spectroscopy, making the detection of very small amounts of molecules possible. Although the investigation of single particles is possible, well-arranged arrays of nanoantennas promise to have greater potential for possible sensor applications since the overall sensitivity can be increased if several nanoantennas interact. In this paper, we report on the IR optical properties of gold nanoantenna arrays and show the dependence of characteristic resonance parameters from the geometrical arrangement of the antennas on the substrate. The stripe-like, polycrystalline gold nanoantennas with rectangular cross-sections were produced by electron beam lithography on silicon wafers. The resonance characteristics were extracted from spectroscopic measurements with our IR microscope. Special focus herein is on interaction between nanoantennas in direction perpendicular to the long particle axis. It is shown that beginning from a crucial distance, the optical properties change dramatically if the gap between the nanoantennas is further decreased.

  20. Ion beam analysis of gold jewelry

    Science.gov (United States)

    Demortier, Guy

    1992-02-01

    PIXE milliprobe in a nonvacuum assembly has been proven to be a very rapid and accurate method for the elemental analysis of gold jewelry artefacts. Using protons whose energy is lower than 3 MeV, it is possible to obtain, in a few minutes, the actual composition (copper, iron, gold, silver, etc.) of narrow parts of artefacts, without any sampling, even at microscopic level. Most of the studies of our group in this field concern solders on these jewelry items. Narrow regions of gold artefacts have also been studied with a PIXE microprobe. They were then irradiated in vacuum. Nuclear reaction analyses induced by 2 MeV deuterons are also performed to identify the presence of light elements and, particularly O, N and S. Traces of these elements are of primary importance to characterize the origin of the ores used in various workmanships. Interferences of X-ray lines of Au with those of traces of Cu and Zn are solved using a method of selective excitation of X-rays of these elements. Analytical results have been interpreted in order to understand the workmanship of goldsmiths from the Antiquity. Fakes and repairs (or ornaments added to original artefacts) may also be identified. The ancient recipes are improved to give new soldering procedures at low temperature.

  1. All That Glitters Is Not Gold

    CERN Multimedia

    2001-01-01

    The surface treatment lab team. From left to right, J. Carosone, M. Malabaila, J-P. Malivert (front row), M. Thiebert, and A. Lasserre (back row). Apiece of stainless steel equipment, destined for the LHC, was delivered to building 102 last Friday morning. This past Monday the equipment emerged from the same building in the afternoon, looking very much the same as it did when it arrived... with one small difference. The equipment was no longer steel, but gold. This may sound like medieval alchemy, but not all is as it appears. In fact there is no sorcery involved, just lots of careful chemical engineering. No wizards either, but rather a talented team of individuals... the CERN surface treatment lab group. Copper, silver, and gold are all incredibly important to particle physics projects because of their ability to conduct electricity with very low resistance. Unfortunately, these metals are also expensive and cannot be used frequently in large quantities. So instead of building equipment out of gold, equi...

  2. X-ray optics of gold nanoparticles.

    Science.gov (United States)

    Letfullin, Renat R; Rice, Colin E W; George, Thomas F

    2014-11-01

    Gold nanoparticles have been investigated as contrast agents for traditional x-ray medical procedures, utilizing the strong absorption characteristics of the nanoparticles to enhance the contrast of the detected x-ray image. Here we use the Kramers-Kronig relation for complex atomic scattering factors to find the real and imaginary parts of the index of refraction for the medium composed of single-element materials or compounds in the x-ray range of the spectrum. These complex index of refraction values are then plugged into a Lorenz-Mie theory to calculate the absorption efficiency of various size gold nanoparticles for photon energies in the 1-100 keV range. Since the output from most medical diagnostic x-ray devices follows a wide and filtered spectrum of photon energies, we introduce and compute the effective intensity-absorption-efficiency values for gold nanoparticles of radii varying from 5 to 50 nm, where we use the TASMIP model to integrate over all spectral energies generated by typical tungsten anode x-ray tubes with kilovolt potentials ranging from 50 to 150 kVp.

  3. Electrodeposition of amorphous gold alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Masaru; Senda, Kazutaka [Central Research Laboratory, Kanto Chemical Co., Inc., Saitama 340-0003 (Japan); Advanced Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Musha, Yuta [Department of Applied Chemistry, School of Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Sasano, Junji [Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, Tokyo 169-0051 (Japan); Okinaka, Yutaka [Advanced Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Osaka, Tetsuya [Department of Applied Chemistry, School of Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, Tokyo 169-0051 (Japan); Advanced Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555 (Japan)], E-mail: osakatet@waseda.jp

    2007-11-20

    The process for electroplating amorphous gold-nickel-tungsten alloy that we developed previously based on the addition of a gold salt to a known amorphous Ni-W electroplating solution was investigated further using the X-ray diffraction (XRD) method for the purpose of quickly surveying the effects of various experimental variables on the microstructure of the alloy. In this system the gold concentration in the plating bath was found to be critical; i.e., when it is either very low or very high, the deposit becomes crystalline to XRD. The deposit composition varies linearly with the mole ratio of Au to Ni in solution, and the alloy deposit is amorphous to XRD when the atomic ratio of Au/Ni in the deposit is between 0.5 and 1.5. At suitable concentrations of the metal ions, the deposit contains essentially no tungsten. By extending the work on the Au-Ni-W system, an amorphous Au-Co alloy plating process was also developed.

  4. Amphoteric properties of gold in zinc selenide

    Energy Technology Data Exchange (ETDEWEB)

    Avdonin, A.N. [Department of Physics, State University of Moldova, A. Mateevich Street 60, MD-2009 Kishinev (Moldova, Republic of); Ivanova, G.N. [Department of Physics, State University of Moldova, A. Mateevich Street 60, MD-2009 Kishinev (Moldova, Republic of); Nedeoglo, D.D. [Department of Physics, State University of Moldova, A. Mateevich Street 60, MD-2009 Kishinev (Moldova, Republic of)]. E-mail: nedeoglo@usm.md; Nedeoglo, N.D. [Department of Physics, State University of Moldova, A. Mateevich Street 60, MD-2009 Kishinev (Moldova, Republic of); Sirkeli, V.P. [Department of Physics, State University of Moldova, A. Mateevich Street 60, MD-2009 Kishinev (Moldova, Republic of)

    2005-08-01

    Hall effect, electric conductivity, and charge carriers mobility in n-ZnSe single crystals doped with gold during the process of a long-term high-temperature annealing in Zn+Au melt with various Au contents were investigated in the temperature range from 77 to 300 K. It has been established that, at low gold concentration, Au atoms form mainly donor-type interstitial Au{sub i} defects. The increase of Au concentration in Zn+Au melt leads to the formation of both simple Au{sub Zn} defects and associative acceptors (Au{sub Zn}-Au{sub i}) (Au{sub Zn}-D{sub Zn}), and (Au{sub Zn}-V{sub Se}). These defects determine electrical properties of the crystals and they are responsible for the complex structure of excitonic and impurity radiation spectra. The influence of dopant concentration on both electrical and luminescent properties of n-ZnSe:Zn:Au crystals is investigated. The observed variations of electrical and luminescent properties are due to amphoteric properties of gold impurity in zinc selenide.

  5. Thermal Stability of Nanoporous Raney Gold Catalyst

    Directory of Open Access Journals (Sweden)

    Matthew C. Tai

    2015-07-01

    Full Text Available Nanoporous “Raney gold” sponge was prepared by de-alloying an Au-Al precursor alloy. Catalytic tests using a micro-reactor confirmed that Raney gold can serve as an active heterogeneous catalyst for CO oxidation, reduction of NO to N2, and oxidation of NO to NO2. In general, the specific surface area of a heterogeneous catalyst has an influence on its catalytic efficacy. Unfortunately, gold sponges coarsen readily, leading to sintering of their structure and reduction in surface area. This potentially places constraints on their upper operating temperature in catalytic reactors. Here we analyzed the behavior of Raney gold when the temperature was raised. We examined the kinetics and mechanism of coarsening of the sponge using a combination of in situ optical measurements and Metropolis Monte Carlo modeling with a Lennard-Jones interatomic potential. Modeling showed that the sponges started with an isotropic “foamy” morphology with negative average “mean curvature” but that subsequent thermally activated coarsening will drive the morphology through a bi-continuous fibrous state and on, eventually, to a sponge consisting of sintered blobs of predominantly positive “mean curvature”.

  6. A luminosity model of RHIC gold runs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.Y.

    2011-11-01

    In this note, we present a luminosity model for RHIC gold runs. The model is applied to the physics fills in 2007 run without cooling, and with the longitudinal cooling applied to one beam only. Having good comparison, the model is used to project a fill with the longitudinal cooling applied to both beams. Further development and possible applications of the model are discussed. To maximize the integrated luminosity, usually the higher beam intensity, smaller longitudinal and transverse emittance, and smaller {beta} are the directions to work on. In past 10 years, the RHIC gold runs have demonstrated a path toward this goal. Most recently, a successful commissioning of the bunched beam stochastic cooling, both longitudinal and transverse, has offered a chance of further RHIC luminosity improvement. With so many factors involved, a luminosity model would be useful to identify and project gains in the machine development. In this article, a preliminary model is proposed. In Section 2, several secondary factors, which are not yet included in the model, are identified based on the RHIC operation condition and experience in current runs. In Section 3, the RHIC beam store parameters used in the model are listed, and validated. In Section 4, the factors included in the model are discussed, and the luminosity model is presented. In Section 5, typical RHIC gold fills without cooling, and with partial cooling are used for comparison with the model. Then a projection of fills with more coolings is shown. In Section 6, further development of the model is discussed.

  7. Titration of gold nanoparticles in phase extraction.

    Science.gov (United States)

    Cheng, Han-Wen; Schadt, Mark J; Zhong, Chuan-Jian

    2015-12-07

    In the organic-aqueous phase transfer process of gold nanoparticles, there are two types of distinctive interfaces involving hydrophilic and hydrophobic ligands, the understanding of which is important for the design of functional nanomaterials for analytical/bioanalytical applications and the control over the nanoparticles' nanoactivity and nanotoxicity in different phases. This report describes new findings of an investigation of the quantitative aspect of ligand ion pairing at the capping monolayer structure that drives the phase extraction of gold nanoparticles. Alkanethiolate-capped gold nanoparticles of 8 nm diameter with high size monodispersity (RSD ∼ 5%) were first derivatized by a ligand place exchange reaction with 11-mercaptoundecanoic acid to form a mixed monolayer shell consisting of both hydrophobic (-CH3) and hydrophilic (-COOH) groups. It was followed by quantitative titration of the resulting nanoparticles with a cationic species (-NR4(+)) in a toluene phase, yielding ion pairing of -NR4(+) and -COO(-) on part of the capping monolayer. Analysis of the phase extraction allowed a quantitative determination of the percentage of ion pairing and structural changes in the capping monolayer on the nanoparticles. The results, along with morphological characterization, are discussed in terms of the interfacial structural changes and their implications on the rational design of surface-functionalized nanoparticles and fine tuning of the interfacial reactivity.

  8. Quantitative gold nanoparticle analysis methods: A review.

    Science.gov (United States)

    Yu, Lei; Andriola, Angelo

    2010-08-15

    Research and development in the area of gold nanoparticles' (AuNPs) preparation, characterization, and applications are burgeoning in recent years. Many of the techniques and protocols are very mature, but two major concerns are with the mass domestic production and the consumption of AuNP based products. First, how many AuNPs exist in a dispersion? Second, where are the AuNPs after digestion by the environment and how many are there? To answer these two questions, reliable and reproducible methods are needed to analyze the existence and the population of AuNP in samples. This review summarized the most recent chemical and particle quantitative analysis methods that have been used to characterize the concentration (in number of moles of gold per liter) or population (in number of particles per mL) of AuNPs. The methods summarized in this review include, mass spectroscopy, electroanalytical methods, spectroscopic methods, and particle counting methods. These methods may count the number of AuNP directly or analyze the total concentration of element gold in an AuNP dispersion.

  9. Biological response of hydrogels embedding gold nanoparticles.

    Science.gov (United States)

    Marsich, Eleonora; Travan, Andrea; Donati, Ivan; Di Luca, Andrea; Benincasa, Monica; Crosera, Matteo; Paoletti, Sergio

    2011-04-01

    A nanocomposite hydrogel based on natural polysaccharides and gold nanoparticles (ACnAu) has been prepared and its biological effects were tested in vitro with both bacteria and eukaryotic cells. Antimicrobial tests showed that AC-nAu gels are effective in killing both gram+ (Staphylococcus aureus) and gram- (Pseudomonas aeruginosa) bacteria. LDH assays pointed at a toxic effect towards eukaryotic cell-lines (HepG2 and MG63), in contrast with the case of silver-based hydrogels; cytofluorimetry studies demonstrated an apoptosis-related mechanism induced by increase of ROS intracellular level which leads to cell death after 24 h of direct contact with AC-nAu gels. In vivo biocompatibility has been evaluated in a rat model, investigating the peri-implant soft tissue reaction after 1 month of implantation. The results show that silver-containing samples induced a fibrotic capsule of the same average thickness of the control sample (devoid of nanoparticles) (∼50 μm), while in the case of gold containing materials the fibrotic capsule was thicker (∼100 μm), confirming a higher biocompatibility for silver-based samples than for gold-based ones.

  10. Ultrafast electron dynamics in gold nanoshells

    Science.gov (United States)

    Westcott, Sarah Linda

    2001-10-01

    In metallic nanostructures, the interaction of excited electrons with the nanostructure surface may result in electron relaxation dynamics that are significantly different than those predicted by electron-lattice coupling. These ultrafast electron dynamics were monitored by pump-probe measurements of the time-resolved change in transmission. Using femtosecond pulses from a cavity-dumped titanium-doped sapphire laser, two types of nanoparticles with a core-shell geometry were studied. Nanoshells are nanoparticles with a dielectric core surrounded by a continuous thin metal shell. For nanoshells, the plasmon resonance wavelength is tunable by changing the core and shell dimensions. For nanoshells with a gold sulfide core and a gold shell, two conditions were observed under which electron relaxation was different than predicted by electron-phonon coupling. First, electron relaxation occurred more rapidly for gold-gold sulfide nanoshells embedded in polymer films than for nanoshells dispersed in water, with lifetimes of 1.6 ps and 3 to 5 ps, respectively. Second, for nanoshells dispersed in water, the electron relaxation lifetime decreased with adsorption of p-aminobenzoic acid (to 1.7 ps) or aniline (to 1.9 ps) on the nanoshells. With adsorbed n-propylamine or p-mercaptobenzoic acid, electron relaxation transpired in 2.8 ps or 2.4 ps, respectively. Density functional theory calculations indicated that the molecules leading to the fastest electron relaxation possessed the largest induced dipole moments near a metal surface. Semicontinuous gold films grown around a silica nanoparticle core exhibited spectral and dynamical optical signatures of the percolation threshold. Compared to continuous shells, the electron dynamics in the semicontinuous shell layer were dramatically different as additional induced bleaching was observed in the first 500 fs. The observed dynamics are consistent with a rate equation model in which the electrons are initially excited in localized

  11. Biosynthesis of Gold Nanoparticles (Green-gold Using Leaf Extract of Terminalia Catappa

    Directory of Open Access Journals (Sweden)

    Balaprasad Ankamwar

    2010-01-01

    Full Text Available The synthesis of eco-friendly nanoparticles is evergreen branch of nanoscience for biomedical application. Low cost of synthesis and non toxicity are main features make it more attractive potential option for biomedical field and elsewhere. Here, we report the synthesis of gold nanoparticles in aqueous medium using Terminalia catappa (Almond leaf extract as the reducing and stabilizing agent. On treating chloroauric acid solutions with Terminalia catappa (TC leaf extract rapid reduction of chloroaurate ions is observed leading to the formation of highly stable gold nanoparticles in solution. TEM analysis of the gold nanoparticles indicated that they ranged in size from 10 to 35 nm with average size of 21.9 nm.

  12. Modification of Gold Surface with Gold Nanoparticles and Cyclohexyl Dithiocarbamate as a Selective Sensor for Cysteine

    Directory of Open Access Journals (Sweden)

    Ehab AlShamaileh

    2013-01-01

    Full Text Available The self-assembly of cyclohexylamine dithiocarbamate (C6DTC on gold (Au and gold nanoparticles (AuNPs was studied electrochemically using cyclic voltammetry (CV. Cyclic voltammetry was used to study the system Fe(CN63-/Fe(CN64- at the electrode surface of (C6DTC/Au and (C6DTC/AuNPs. The application of the resulting chemically modified surface as a selective sensor for cysteine, among other amino acids, was investigated. Linear oxidative desorption technique was used to characterize the modified electrode that consists of the self-assembled monolayer of cyclohexylamine dithiocarbamate on gold nanoparticles deposited on Au electrode (C6DTC/AuNPs/Au. The results showed an enhancement in the oxidation peak of cysteine on the modified electrode and hence a greater sensitivity.

  13. Manganese oxides supported on gold nanoparticles: new findings and current controversies for the role of gold.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Hosseini, Seyedeh Maedeh; Hołyńska, Małgorzata; Tomo, Tatsuya; Allakhverdiev, Suleyman I

    2015-12-01

    We synthesized manganese oxides supported on gold nanoparticles (diameter gold nanoparticles under hydrothermal conditions. In this green method Mn oxide is deposited on the gold nanoparticles. The compounds were characterized by scanning electron microscopy, energy-dispersive spectrometry, high-resolution transmission electron microscopy, X-ray diffraction, UV-Vis spectroscopy, Fourier transform infrared spectroscopy, and atomic absorption spectroscopy. In the next step, the water-oxidizing activities of these compounds in the presence of cerium(IV) ammonium nitrate as a non-oxo transfer oxidant were studied. The results show that these compounds are good catalysts toward water oxidation with a turnover frequency of 1.0 ± 0.1 (mmol O2/(mol Mn·s)). A comparison with other previously reported Mn oxides and important factors influencing the water-oxidizing activities of Mn oxides is also discussed.

  14. An Application of Microwave Pre-oxidation in Improving Gold Recovery of a Refractory Gold Ore

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Microwave radiation was employed as a pretreating technology to oxidise a refractory gold ore. Heating characteristics showed that, in an identical microwave field, the bulk temperature of the sample increased with microwave power, microwave radiation time and particle size. The rate of sulphur removal increased with microwave radiation time. Particle size also had a significant effect on the oxidation rate. Pyrite and marcasite could be oxidised into Fe2O3 with a high porous structure. When microwave radiation was carried out in a rotary bed, the oxidation was more uniformly developed, in comparison with in a fixed bed. Gold extraction by cyanidation could be remarkably improved after the ore was subjected to microwave radiation. The results showed that gold recovery could be improved from 37% to 69%~81.2%.

  15. Plasmonic phototherapy using gold nanospheres and gold nanorods irradiated with light-emitting diodes

    Science.gov (United States)

    Poorani, Gananathan; Rao, Aruna Prakasa; Singaravelu, Ganesan; Manickam, Elanchezhiyan

    2016-04-01

    Gold nanoparticles (GNPs) provide different modes of therapeutic responses in cells depending on their size and shape. We have studied two modifications of GNPs exhibiting surface plasmon resonances (SPRs) with phototherapeutic effects in nonmalignant Vero and malignant HeLa cell lines. The cells were treated with 30-nm-size gold nanospheres (GNSs) (having SPR at a wavelength of 530 nm) and with gold nanorods (GNRs) (having SPR at 630 nm). The plasmonic phototherapy effect in cells was provided by irradiating them with green and red light-emitting diodes (LEDs). The cytotoxicities of GNPs were determined by MTT assay. Both the GNSs and GNRs were found to be biocompatible and have efficient phototherapeutic activity with LEDs.

  16. Gold-alkynyls in catalysis: alkyne activation, gold cumulenes and nuclearity.

    Science.gov (United States)

    Halliday, Connor J V; Lynam, Jason M

    2016-08-09

    The use of cationic gold(i) species in the activation of substrates containing C[triple bond, length as m-dash]C bonds has become a valuable tool for synthetic chemists. Despite the seemingly simple label of 'alkyne activation', numerous patterns of reactivity and product structure are observed in systems employing related substrates and catalysts. The complications of mechanistic determination are compounded as the number of implicated gold(i) centres involved in catalysis increases and debate about the bonding in proposed intermediates clouds the number and importance of potential reaction pathways. This perspective aims to illustrate some of the principles underpinning gold-alkynyl interactions whilst highlighting some of the contentious areas in the field and offering some insight into other, often ignored, mechanistic possibilities based on recent findings.

  17. The giant Kalgoorlie Gold Field revisited

    Institute of Scientific and Technical Information of China (English)

    Noreen Mary Vielreicher; David Ian Groves; Neal Jesse McNaughton

    2016-01-01

    The Neoarchaean Kalgoorlie Gold Field contains the giant Golden Mile and world-class Mt Charlotte deposits, which have been the subject of much research for over 100 years. The Golden Mile deposit is a complex array of ductile to brittle vein and breccia lodes that are predominantly hosted in the highly-fractionated Golden Mile Dolerite sill. The Fimiston lodes comprise an array of narrow lodes that evolved broadly syn- to late-formation of the regional D2 NW-trending foliation. The lodes are charac-terized by pyrite veinlets and disseminations, quartz veinlets and breccias, and banded quartz-carbonate veins with sericite, carbonate, and pyrite-dominated alteration. Bonanza Green-Leader, or Oroya-style, lodes, with grades in excess of 1000 g/t Au, are similar to the Fimiston-style lodes, but are character-ized by abundant visible gold, native tellurium and more abundant telluride minerals within roscoelite-bearing alteration zones. The arguably structurally younger Mt Charlotte-style lodes are characterized by a pipe-shaped, coarse-grained quartz, carbonate and scheelite vein-stockwork with distinct vertically-zoned, carbonate-sericite-albite-pyrite ? pyrrhotite dominant alteration assemblages around veins within Unit 8 of the Golden Mile dolerite and porphyry dykes. The network of steep-and gently-dipping extension and shear fracture-fill veins are associated with NE-trending fault sets that cross cut the regional NW-trend. The deposit area is intruded by swarms of porphyry dykes, including syn-volcanic mafic dykes, early and volumetrically most significant c. 2.67 Ga feldspar-phyric porphyry dykes, as well as later c. 2.66‒2.65 Ga calc-alkaline hornblende-phyric dykes associated with younger c. 2.65‒2.64 Ga lamprophyre dykes. All post-volcanic dykes have similar orientations to the Fimiston lodes. The feldspar dykes are clearly overprinted by all styles of mineralization, although the relationship between hornblende-phyric and lamprophyre dykes and gold

  18. Synthesis of gold nanoparticles using various amino acids.

    Science.gov (United States)

    Maruyama, Tatsuo; Fujimoto, Yuhei; Maekawa, Tetsuya

    2015-06-01

    Gold nanoparticles (4-7nm) were synthesized from tetraauric acid using various amino acids as reducing and capping agents. The gold nanoparticles were produced from the incubation of a AuCl4(-) solution with an amino acid at 80°C for 20min. Among the twenty amino acids tested, several amino acids produced gold nanoparticles. The color of the nanoparticle solutions varied with the amino acids used for the reduction. We adopted l-histidine as a reducing agent and investigated the effects of the synthesis conditions on the gold nanoparticles. The His and AuCl4(-) concentrations affected the size of the gold nanoparticles and their aggregates. The pH of the reaction solution also affected the reaction yields and the shape of the gold nanoparticles.

  19. Microbial synthesis of gold nanoparticles: current status and future prospects.

    Science.gov (United States)

    Shedbalkar, Utkarsha; Singh, Richa; Wadhwani, Sweety; Gaidhani, Sharvari; Chopade, B A

    2014-07-01

    Gold nanoparticles have been employed in biomedicine since the last decade because of their unique optical, electrical and photothermal properties. Present review discusses the microbial synthesis, properties and biomedical applications of gold nanoparticles. Different microbial synthesis strategies used so far for obtaining better yield and stability have been described. It also includes different methods used for the characterization and analysis of gold nanoparticles, viz. UV-visible spectroscopy, Fourier transform infrared spectroscopy, X ray diffraction spectroscopy, scanning electron microscopy, ransmission electron microscopy, atomic force microscopy, electron dispersive X ray, X ray photoelectron spectroscopy and cyclic voltametry. The different mechanisms involved in microbial synthesis of gold nanoparticles have been discussed. The information related to applications of microbially synthesized gold nanoparticles and patents on microbial synthesis of gold nanoparticles has been summarized.

  20. Shape-tailoring and catalytic function of anisotropic gold nanostructures

    Directory of Open Access Journals (Sweden)

    Premkumar Thathan

    2011-01-01

    Full Text Available Abstract We report a facile, one-pot, shape-selective synthesis of gold nanoparticles in high yield by the reaction of an aqueous potassium tetrachloroaurate(III solution with a commercially available detergent. We prove that a commercial detergent can act as a reducing as well as stabilizing agent for the synthesis of differently shaped gold nanoparticles in an aqueous solution at an ambient condition. It is noteworthy that the gold nanoparticles with different shapes can be prepared by simply changing the reaction conditions. It is considered that a slow reduction of the gold ions along with shape-directed effects of the components of the detergent plays a vital function in the formation of the gold nanostructures. Further, the as-prepared gold nanoparticles showed the catalytic activity for the reduction reaction of 4-nitrophenol in the presence of sodium borohydride at room temperature.

  1. SERS decoding of micro gold shells moving in microfluidic systems.

    Science.gov (United States)

    Lee, Saram; Joo, Segyeong; Park, Sejin; Kim, Soyoun; Kim, Hee Chan; Chung, Taek Dong

    2010-05-01

    In this study, in situ surface-enhanced Raman scattering (SERS) decoding was demonstrated in microfluidic chips using novel thin micro gold shells modified with Raman tags. The micro gold shells were fabricated using electroless gold plating on PMMA beads with diameter of 15 microm. These shells were sophisticatedly optimized to produce the maximum SERS intensity, which minimized the exposure time for quick and safe decoding. The shell surfaces produced well-defined SERS spectra even at an extremely short exposure time, 1 ms, for a single micro gold shell combined with Raman tags such as 2-naphthalenethiol and benzenethiol. The consecutive SERS spectra from a variety of combinations of Raman tags were successfully acquired from the micro gold shells moving in 25 microm deep and 75 microm wide channels on a glass microfluidic chip. The proposed functionalized micro gold shells exhibited the potential of an on-chip microfluidic SERS decoding strategy for micro suspension array.

  2. Biodistribution of gold nanoparticles following intratracheal instillation in mouse lung

    DEFF Research Database (Denmark)

    Sadauskas, Evaldas; Jacobsen, Nicklas R.; Danscher, Gorm

    2009-01-01

    repeatedly during 3 weeks, the load was substantial. Ultrastructurally, AMG silver enhanced gold nanoparticles were found in lysosome-/endosome-like organelles of the macrophages and analysis with AMG, ICP-MS and NAA of the liver revealed an almost total lack of translocation of nanoparticles. In mice given......Background The fate of gold nanoparticles, 2, 40 and 100 nm, administered intratracheally to adult female mice was examined. The nanoparticles were traced by autometallography (AMG) at both ultrastructural and light microscopic levels. Also, the gold content was quantified by inductively coupled...... plasma mass spectrometry (ICP-MS) and neutron activation analysis (NAA). The liver is the major site of deposition of circulating gold nanoparticles. Therefore the degree of translocation was determined by the hepatic deposition of gold. Mice were instilled with 5 intratracheal doses of gold...

  3. Detection of squamous carcinoma cells using gold nanoparticles

    Science.gov (United States)

    Dai, Wei-Yun; Lee, Sze-tsen; Hsu, Yih-Chih

    2015-03-01

    The goal of this study is to use gold nanoparticle as a diagnostic agent to detect human squamous carcinoma cells. Gold nanoparticles were synthesized and the gold nanoparticle size was 34.3 ± 6.2 nm. Based on the over-expression of epidermal growth factor receptor (EGFR) biomarkers in squamous carcinoma cells, we hypothesized that EGFR could be a feasible biomarker with a target moiety for detection. We further modified polyclonal antibodies of EGFR on the surface of gold nanoparticles. We found selected squamous carcinoma cells can be selectively detected using EGFR antibody-modified gold nanoparticles via receptor-mediated endocytosis. Cell death was also examined to determine the survival status of squamous carcinoma cells with respect to gold nanoparticle treatment and EGFR polyclonal antibody modification.

  4. Electronic Transport Properties through Gold-Dithiol-Molecule-Gold Junctions in Equilibrium

    Institute of Scientific and Technical Information of China (English)

    NING Zhan-Yu; CHEN Jing-Zhe; HOU Shi-Min; ZHANG Jia-Xing; LIANG Zhen-Yu; ZHANG Jin; HAN Ru-Shan

    2005-01-01

    @@ We consider the electronic transport through gold-dithiol-molecule-gold junctions. We used an atomicallycontacted extended molecule model for the description of such systems. The calculations are based on the matrix Green function method combined with the hybrid tight-binding density functional theory. In order to determine the position of Fermi level, we referenced the experimental results from ultraviolet photoelectron spectroscopy.Our calculation of molecular conductance near the Fermi level qualitatively reproduces the experimental values measured previously [Science 301 (2003) 1221; J. Am. Chem. Soc. 125 (2003) 16164; Nano Lett. 4 (2004) 267].In addition, we discuss the relationship between different molecular electronic structures and transport properties.

  5. Synthesis of porous gold nanoshells by controlled transmetallation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Pattabi, Manjunatha, E-mail: manjupattabi@yahoo.com; M, Krishnaprabha [Department of Materials Science, Mangalore University, Mangalagangothri-574199 (India)

    2015-06-24

    Aqueous synthesis of porous gold nanoshells in one step is carried out through controlled transmetallation (TM) reaction using a naturally available egg shell membrane (ESM) as a barrier between the sacrificial silver particles (AgNPs) and the gold precursor solution (HAuCl{sub 4}). The formation of porous gold nanoshells via TM reaction is inferred from UV-Vis spectroscopy and the scanning electron microscopic (SEM) studies.

  6. Site-Specific Biomolecule Labeling with Gold Clusters

    OpenAIRE

    Ackerson, Christopher J.; Powell, Richard D.; Hainfeld, James F.

    2010-01-01

    Site-specific labeling of biomolecules in vitro with gold clusters can enhance the information content of electron cryomicroscopy experiments. This chapter provides a practical overview of well-established techniques for forming biomolecule/gold cluster conjugates. Three bioconjugation chemistries are covered: Linker-mediated bioconjugation, direct gold–biomolecule bonding, and coordination-mediated bonding of nickel(II) nitrilotriacetic acid (NTA)-derivatized gold clusters to polyhistidine (...

  7. Forecasting the price of gold: An error correction approach

    Directory of Open Access Journals (Sweden)

    Kausik Gangopadhyay

    2016-03-01

    Full Text Available Gold prices in the Indian market may be influenced by a multitude of factors such as the value of gold in investment decisions, as an inflation hedge, and in consumption motives. We develop a model to explain and forecast gold prices in India, using a vector error correction model. We identify investment decision and inflation hedge as prime movers of the data. We also present out-of-sample forecasts of our model and the related properties.

  8. Chitosan-mediated synthesis of carbon nanotube-gold nanohybrids

    Institute of Scientific and Technical Information of China (English)

    GRAVEL; Edmond; FOILLARD; Stéphanie; DORIS; Eric

    2010-01-01

    Metal-nanotube nanohybrids were produced by in situ synthesis and stabilization of gold nanoparticles on chitosan-functionalized carbon nanotubes.The formation of gold nanoparticles from tetrachloroauric acid was observed after only a few minutes of contact with the functionalized nanotubes,at room temperature.These results suggest that adsorption of chitosan at the surface of carbon nanotubes permits smooth reduction of the metallic salt and efficient anchoring of gold nanoparticles to the nanotubes.

  9. Direct evidence for ferromagnetic spin polarization in gold nanoparticles

    OpenAIRE

    Yamamoto, Y; Miura, T; Teranishi, T.; Miyake, M.; Hori, H.; Suzuki, M.; Kawamura, N.; Miyagawa, H; T. Nakamura; Kobayashi, K

    2004-01-01

    We report the first direct observation of ferromagnetic spin polarization of Au nanoparticles with a mean diameter of 1.9 nm using X-ray magnetic circular dichroism (XMCD). Owing to the element selectivity of XMCD, only the gold magnetization is explored. Magnetization of gold atoms estimated by XMCD shows a good agreement with the results obtained by conventional magnetometry. This result is evidence of intrinsic spin polarization in nano-sized gold.

  10. Direct Observation of Ferromagnetic Spin Polarization in Gold Nanoparticles

    OpenAIRE

    Yamamoto, Y; Miura, T; Suzuki, M.; Kawamura, N.; Miyagawa, H; T. Nakamura; Kobayashi, K; Teranishi, T.; Hori, H.

    2004-01-01

    We report the first direct observation of ferromagnetic spin polarization of Au nanoparticles with a mean diameter of 1.9 nm using x-ray magnetic circular dichroism (XMCD). Owing to the element selectivity of XMCD, only the gold magnetization is explored. Magnetization of gold atoms as estimated by XMCD shows a good agreement with results obtained by conventional magnetometry. This evidences intrinsic spin polarization in nanosized gold.

  11. Fungal Biorecovery of Gold From E-waste.

    Science.gov (United States)

    Bindschedler, Saskia; Vu Bouquet, Thi Quynh Trang; Job, Daniel; Joseph, Edith; Junier, Pilar

    2017-01-01

    Waste electric and electronic devices (e-waste) represent a source of valuable raw materials of great interest, and in the case of metals, e-waste might become a prized alternative source. Regarding gold, natural ores are difficult to mine due to their refractory nature and the richest ores have almost all been exploited. Additionally, some gold mining areas are present in geopolitically unstable regions. Finally, the gold mining industry produces toxic compounds, such as cyanides. As a result, the gold present in e-waste represents a nonnegligible resource (urban mining). Extraction methods of gold from natural ores (pyro- and hydrometallurgy) have been adapted to this particular type of matrix. However, to propose novel approaches with a lower environmental footprint, biotechnological methods using microorganisms are being developed (biometallurgy). These processes use the extensive metabolic potential of microbes (algae, bacteria, and fungi) to mobilize and immobilize gold from urban and industrial sources. In this review, we focus on the use of fungi for gold biomining. Fungi interact with gold by mobilizing it through mechanical attack as well as through biochemical leaching by the production of cyanides. Moreover, fungi are also able to release Au through the degradation of cyanide from aurocyanide complexes. Finally, fungi immobilize gold through biosorption, bioaccumulation, and biomineralization, in particular, as gold nanoparticles. Overall, the diversity of mechanisms of gold recycling using fungi combined with their filamentous lifestyle, which allows them to thrive in heterogeneous and solid environments such as e-waste, makes fungi an important bioresource to be harnessed for the biorecovery of gold. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Gold Ion-Angiotensin Peptide Interaction by Mass Spectrometry

    Science.gov (United States)

    Lee, Jenny; Jayathilaka, Lasanthi P.; Gupta, Shalini; Huang, Jin-Sheng; Lee, Bao-Shiang

    2012-05-01

    Stimulated by the interest in developing gold compounds for treating cancer, gold ion-angiotensin peptide interactions are investigated by mass spectrometry. Under the experimental conditions used, the majority of gold ion-angiotensin peptide complexes contain gold in the oxidation states I and III. Both ESI-MS and MALDI-TOF MS detect singly/multiply charged ions for mononuclear/multinuclear gold-attached peptides, which are represented as [peptide + a Au(I) + b Au(III) + (e - a -3b) H]e+, where a,b ≥ 0 and e is charge. ESI-MS data shows singly/multiply charged ions of Au(I)-peptide and Au(III)-peptide complexes. This study reveals that MALDI-TOF MS mainly detects singly charged Au(I)-peptide complexes, presumably due to the ionization process. The electrons in the MALDI plume seem to efficiently reduce Au(III) to Au(I). MALDI also tends to enhance the higher polymeric forms of gold-peptide complexes regardless of the laser power used. Collision-induced dissociation experiments of the mononuclear and dinuclear gold-attached peptide ions for angiotensin peptides show that the gold ion (a soft acid) binding sites are in the vicinity of Cys (a soft ligand), His (a major anchor of peptide for metal ion chelation), and the basic residue Arg. Data also suggests that the abundance of gold-attached peptides increases with higher gold concentration until saturation, after which an increase in gold ion concentration leads to the aggregation and/or precipitation of gold-bound peptides.

  13. Functionalized Gold Nanorods for Tumor Imaging and Targeted Therapy

    OpenAIRE

    Gui, Chen; Cui, Da-Xiang

    2012-01-01

    Gold nanorods, as an emerging noble metal nanomaterial with unique properties, have become the new exciting focus of theoretical and experimental studies in the past few years. The structure and function of gold nanorods, especially their biocompatibility, optical property, and photothermal effects, have been attracting more and more attention. Gold nanorods exhibit great potential in applications such as tumor molecular imaging and photothermal therapy. In this article, we review some of the...

  14. Gold nanoparticles as novel agents for cancer therapy.

    Science.gov (United States)

    Jain, S; Hirst, D G; O'Sullivan, J M

    2012-02-01

    Gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated as drug carriers, photothermal agents, contrast agents and radiosensitisers. This review introduces the field of nanotechnology with a focus on recent gold nanoparticle research which has led to early-phase clinical trials. In particular, the pre-clinical evidence for gold nanoparticles as sensitisers with ionising radiation in vitro and in vivo at kilovoltage and megavoltage energies is discussed.

  15. Deflagration-to-detonation transition in gases in tubes with cavities

    Science.gov (United States)

    Smirnov, N. N.; Nikitin, V. F.; Phylippov, Yu. G.

    2010-12-01

    DDT control in gaseous fuel-air mixtures became very acute. This paper contains results of theoretical and experimental investigations of DDT processes in combustible gaseous mixtures. In particular, the paper investigates the effect of cavities incorporated in detonation tubes at the onset of detonation in gases. Extensive numerical modeling and simulations allowed studying the features of deflagration-to-detonation transition in gases in tubes incorporating cavities of a wider cross section. The presence of cavities substantially affects the combustion modes being established in the device and their dependence on the governing parameters of the problem. The influence of geometrical characteristics of the confinement and flow turbulization on the onset of detonation and the influence of temperature and fuel concentration in the unburned mixture are discussed. It was demonstrated both experimentally and theoretically that the presence of cavities of wider cross section in the ignition part of the tube promotes DDT and shortens the predetonation length. At the same time, cavities incorporated along the whole length or in the far-end section inhibit detonation and bring about the onset of low-velocity galloping detonation or galloping combustion modes. The presence of cavities in the ignition section turns an increase in the initial mixture temperature into a DDT-promoting factor instead of a DDT-inhibiting factor.

  16. Reflectance spectroscopy of gold nanoshells: computational predictions and experimental measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Alex W. H.; Lewinski, Nastassja A.; Lee, Min-Ho; Drezek, Rebekah A. [Rice University, Department of Bioengineering (United States)], E-mail: drezek@rice.edu

    2006-10-15

    Gold nanoshells are concentric spherical constructs that possess highly desirable optical responses in the near infrared. Gold nanoshells consist of a thin outer gold shell and a silica core and can be used for both diagnostic and therapeutic purposes by tuning the optical response through changing the core-shell ratio as well as the overall size. Although optical properties of gold nanoshells have already been well documented, the reflectance characteristics are not well understood and have not yet been elucidated by experimental measurements. Yet, in order to use gold nanoshells as an optical contrast agent for scattering-based optical methods such as reflectance spectroscopy, it is critical to characterize the reflectance behavior. With this in mind, we used a fiber-optic-based spectrometer to measure diffuse reflectance of gold nanoshell suspensions from 500 nm to 900 nm. Experimental results show that gold nanoshells cause a significant increase in the measured reflectance. Spectral features associated with scattering from large angles ({approx}180 deg.) were observed at low nanoshell concentrations. Monte Carlo modeling of gold nanoshells reflectance demonstrated the efficacy of using such methods to predict diffuse reflectance. Our studies suggest that gold nanoshells are an excellent candidate as optical contrast agents and that Monte Carlo methods are a useful tool for optimizing nanoshells best suited for scattering-based optical methods.

  17. Reflectance spectroscopy of gold nanoshells: computational predictions and experimental measurements

    Science.gov (United States)

    Lin, Alex W. H.; Lewinski, Nastassja A.; Lee, Min-Ho; Drezek, Rebekah A.

    2006-10-01

    Gold nanoshells are concentric spherical constructs that possess highly desirable optical responses in the near infrared. Gold nanoshells consist of a thin outer gold shell and a silica core and can be used for both diagnostic and therapeutic purposes by tuning the optical response through changing the core-shell ratio as well as the overall size. Although optical properties of gold nanoshells have already been well documented, the reflectance characteristics are not well understood and have not yet been elucidated by experimental measurements. Yet, in order to use gold nanoshells as an optical contrast agent for scattering-based optical methods such as reflectance spectroscopy, it is critical to characterize the reflectance behavior. With this in mind, we used a fiber-optic-based spectrometer to measure diffuse reflectance of gold nanoshell suspensions from 500 nm to 900 nm. Experimental results show that gold nanoshells cause a significant increase in the measured reflectance. Spectral features associated with scattering from large angles ( 180°) were observed at low nanoshell concentrations. Monte Carlo modeling of gold nanoshells reflectance demonstrated the efficacy of using such methods to predict diffuse reflectance. Our studies suggest that gold nanoshells are an excellent candidate as optical contrast agents and that Monte Carlo methods are a useful tool for optimizing nanoshells best suited for scattering-based optical methods.

  18. GOLD NANOPARTICLES: A REVIVAL IN PRECIOUS METAL ADMINISTRATION TO PATIENTS

    Science.gov (United States)

    Thakor, AS; Jokerst, J; Zaveleta, C; Massoud, TF; Gambhir, SS

    2011-01-01

    Gold has been used as a therapeutic agent to treat a wide variety of rheumatic diseases including psoriatic arthritis, juvenile arthritis and discoid lupus erythematosus. Although the use of gold has been largely superseded by newer drugs, gold nanoparticles are being used effectively in laboratory based clinical diagnostic methods whilst concurrently showing great promise in vivo either as a diagnostic imaging agent or a therapeutic agent. For these reasons, gold nanoparticles are therefore well placed to enter mainstream clinical practice in the near future. Hence, the present review summarizes the chemistry, pharmacokinetics, bio-distribution, metabolism and toxicity of bulk gold in humans based on decades of clinical observation and experiments in which gold was used to treat patients with rheumatoid arthritis. The beneficial attributes of gold nanoparticles, such as their ease of synthesis, functionalization and shape control are also highlighted demonstrating why gold nanoparticles are an attractive target for further development and optimization. The importance of controlling the size and shape of gold nanoparticles to minimize any potential toxic side effects is also discussed. PMID:21846107

  19. Synthesis of anisotropic gold shell on carbon nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Minati, L., E-mail: luminati@fbk.eu [CNR-IFN, CSMFO Lab. (Italy); Torrengo, S. [FBK (Italy); Ischia, G. [University of Trento, Department of Industrial Engineering (Italy); Speranza, G. [FBK (Italy)

    2013-11-15

    This paper reports a simple procedure to synthesize gold-coated carbon nanotubes. The method involves the reduction of gold precursor on oxidized carbon nanotubes. UV–Visible absorption spectroscopy and electron microscopy were used to study the gold precursor reduction on the carbon nanotubes. Scanning and transmission electron microscopy analysis showed the formation of an irregular gold layer around the CNT surface. The resulting nanoparticles show an anisotropic shape with dimensions between 100 and 200 nm. This hybrid material displays an intense absorption in the near infrared range with an absorption maximum at 840 nm.

  20. Colloidal gold and silica in mesothermal vein systems

    Science.gov (United States)

    Herrington, R. J.; Wilkinson, J. J.

    1993-06-01

    Some of the textural features of mesothermal gold-quartz veins may be best explained by the initial precipitation of amorphous silica gel (colloid), which subsequently crystallizes to quartz. This can occur in brittle-ductile shear zones where a significant fluid-pressure drop occurs during stick-slip failure. Such a process rapidly supersaturates the hydrothermal fluid with respect to amorphous silica, which precipitates instead of quartz, owing to favorable kinetics. Depressurization also commonly leads to fluid unmixing and destabilization of soluble gold complexes. However, the presence of colloidal silica can stabilize gold colloid, allowing further transport of particulate gold in suspension in the hydrothermal fluid. Silica gel would be highly unstable under mesothermal conditions and would undergo rapid syneresis and crystallization to form quartz; solid impurities would tend to be expelled toward grain boundaries. This model can account for the primary anhedral aggregate textures typical of mesothermal quartz veins, the concentration of gold along grain boundaries and the formation of discrete gold nuggets, and the rare occurrence of low-order silica polymorphs and relict spheroidal structures. The transport of gold in colloidal form may be one reason for the frequently consistent bulk grade distribution in gold-quartz vein systems over many hundreds of metres (in some cases kilometres) of depth. In addition, the formation of charged colloidal particles may help to explain the attraction of gold grains to specific mineral surfaces.

  1. Multiple gold-dimer detection from large scattering background

    Science.gov (United States)

    Hong, Xin; Jin, Zheng

    2016-10-01

    Gold nanoparticles exhibit unique plasmonic optical properties in visible to near infrared band. Especially the coupling effect existing at the gap between a closely linked particle pair can make the local field strongly enhanced. These properties make gold particles more attractive to be employed as molecular probes in biomedical related fundamental and clinical researches. However in the bio-system exist many large molecules or groups, whose optical signals can strongly depress the gold particles without detectable. In this paper, we proposed a method to extract the targets which are labelled by gold dimer pairs from large scattering background.

  2. Preparation and characterization of graphene oxide encapsulated gold nanoparticles.

    Science.gov (United States)

    Yun, Yong Ju; Song, Ki-Bong

    2013-11-01

    We present a simple approach for the fabrication of graphene oxide-encapsulated gold nanoparticles using graphene oxide sheet-wrapping via electrostatic self-assembly. By mixing bovine serum albumin molecule-functionalized gold nanoparticles with graphene oxide dispersion, positively charged bovine serum albumin/gold nanoparticles easily assembled with negatively charged graphene oxide sheets through electrostatic interaction. Transmittance electron microscopy, scanning electron microscopy, atomic force microscopy, and Raman spectroscopy were used to confirm the encapsulation of graphene oxide on gold nanoparticles. Interestingly, graphene oxide sheets wrapping mainly occurs along the main body of single or a few gold nanoparticles. Additionally, by measuring the ultraviolet-visible spectroscopy spectrum, we found that the surface plasmon resonances band of the graphene oxide-encapsulated gold nanoparticles was found to become red-shifted compared to that of pristine gold nanoparticles, whereas similar to that of bovine serum albumin-coated gold nanoparticles. These results indicating that most of graphene oxide-encapsulated gold nanoparticles have good monodispersity and spherical shape. These resulting materials may potentially serve as a platform for plasmon resonance electron transfer spectroscopy or a probe for low level biosensing.

  3. ECONOMIC EVALUATION OF GOLD-ORE DUMP REPROCESSING EFFICIENCY

    Directory of Open Access Journals (Sweden)

    N. Y. Samsonov

    2010-06-01

    Full Text Available An economic projection is presented in the paper on the heap leaching technology for extracting a residual gold from the gold-ore dumps accumulated at the exploited or closed gold mines. A brief analysis is performed on the legal status of use this source of raw materials, availability and efficiency of the heap leaching method are reviewed, and the potential users of this method are assessed. An investment plan is created for involving anthropogenic dumps of gold-raw materials at one of the ore deposits in Siberia (heap complex of the North-Western flank of the Sovetskoye minefield, Krasnoyarsk region, North-Yenisey area.

  4. Methanobactin-mediated one-step synthesis of gold nanoparticles.

    Science.gov (United States)

    Xin, Jia-ying; Cheng, Dan-dan; Zhang, Lan-xuan; Lin, Kai; Fan, Hong-chen; Wang, Yan; Xia, Chun-gu

    2013-11-01

    Preparation of gold nanoparticles with a narrow size distribution has enormous importance in nanotechnology. Methanobactin (Mb) is a copper-binding small peptide that appears to function as an agent for copper sequestration and uptake in methanotrophs. Mb can also bind and catalytically reduce Au (III) to Au (0). In this study, we demonstrate a facile Mb-mediated one-step synthetic route to prepare monodispersed gold nanoparticles. Continuous reduction of Au (III) by Mb can be achieved by using hydroquinone as the reducing agent. The gold nanoparticles have been characterized by UV-visible spectroscopy. The formation and the surface plasmon resonance properties of the gold nanoparticles are highly dependent on the ratio of Au (III) to Mb in solution. X-ray photoelectron spectroscopy (XPS), fluorescence spectra and Fourier transform-infrared spectroscopy (FT-IR) spectra suggest that Mb molecules catalytically reduce Au (III) to Au (0) with the concomitant production of gold nanoparticles, and then, Mb statically adsorbed onto the surface of gold nanoparticles to form an Mb-gold nanoparticles assembly. This avoids secondary nucleation. The formed gold nanoparticles have been demonstrated to be monodispersed and uniform by transmission electron microscopy (TEM) images. Analysis of these particles shows an average size of 14.9 nm with a standard deviation of 1.1 nm. The gold nanoparticles are extremely stable and can resist aggregation, even after several months.

  5. Longitudinal Plasmonic Detection of Glucose Using Gold Nanorods

    Directory of Open Access Journals (Sweden)

    Ching-An Peng

    2014-04-01

    Full Text Available Gold nanorod-based affinity sensors were developed\tutilizing\tconcanavalin-A/dextran/glucose chemistry to detect glucose. The gold nanorods, synthesized using the seed-mediated method, were first coated with dextran sulfate. The dextran sulfate coating changed the local refractive index, which was observed as a red shift in the longitudinal plasmon band. After the addition of 8 μM concanavalin-A, gold nanorod aggregates were formed as shown by TEM analysis. The corresponding UV-Vis spectrum peak wavelength showed a red shift from 701 nm of dextran sulfate coated gold nanorods to 718 nm of concanavalin-A promoted gold nanorod aggregates. The gold nanorod aggregates were dissociated when 12 mM glucose was introduced, as illustrated by TEM images. The longitudinal plasmon resonance of the UV-Vis spectrum also showed a blue shift from 718 nm of dextran sulfate-coated gold nanorods associated by concanavalin-A to 714 nm of dissociated dextran sulfate-coated gold nanorods. The degree of the spectrum peak wavelength shift of the dextran sulfate-coated gold nanorods associated by concanavalin-A can be modulated using glucose ranging from 1 to 30 mM.

  6. Porous Gold Films Fabricated by Wet-Chemistry Processes

    Directory of Open Access Journals (Sweden)

    Aymeric Pastre

    2016-01-01

    Full Text Available Porous gold films presented in this paper are formed by combining gold electroless deposition and polystyrene beads templating methods. This original approach allows the formation of conductive films (2 × 106 (Ω·cm−1 with tailored and interconnected porosity. The porous gold film was deposited up to 1.2 μm on the silicon substrate without delamination. An original zirconia gel matrix containing gold nanoparticles deposited on the substrate acts both as an adhesion layer through the creation of covalent bonds and as a seed layer for the metallic gold film growth. Dip-coating parameters and gold electroless deposition kinetics have been optimized in order to create a three-dimensional network of 20 nm wide pores separated by 20 nm thick continuous gold layers. The resulting porous gold films were characterized by GIXRD, SEM, krypton adsorption-desorption, and 4-point probes method. The process is adaptable to different pore sizes and based on wet-chemistry. Consequently, the porous gold films presented in this paper can be used in a wide range of applications such as sensing, catalysis, optics, or electronics.

  7. Accelerated atmospheric corrosion testing of electroplated gold mirror coatings

    Science.gov (United States)

    Chu, C.-T.; Alaan, D. R.; Taylor, D. P.

    2010-08-01

    Gold-coated mirrors are widely used in infrared optics for industrial, space, and military applications. These mirrors are often made of aluminum or beryllium substrates with polished nickel plating. Gold is deposited on the nickel layer by either electroplating or vacuum deposition processes. Atmospheric corrosion of gold-coated electrical connectors and contacts was a well-known problem in the electronic industry and studied extensively. However, there is limited literature data that correlates atmospheric corrosion to the optical properties of gold mirror coatings. In this paper, the atmospheric corrosion of different electroplated gold mirror coatings were investigated with an accelerated mixed flowing gas (MFG) test for up to 50 days. The MFG test utilizes a combination of low-level air pollutants, humidity, and temperatures to achieve a simulated indoor environment. Depending on the gold coating thickness, pore corrosion started to appear on samples after about 10 days of the MFG exposure. The corrosion behavior of the gold mirror coatings demonstrated the porous nature of the electroplated gold coatings as well as the variation of porosity to the coating thickness. The changes of optical properties of the gold mirrors were correlated to the morphology of corrosion features on the mirror surface.

  8. Electrical properties of gold at dislocations in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Voss, O.; Kveder, V.V.; Schroeter, W.; Seibt, M. [IV. Physikalisches Institut der Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)

    2005-04-01

    Deep level transient spectroscopy has been used to study deep levels in plastically deformed n-type silicon introduced by gold impurities at concentrations differing by about one order of magnitude. A DLTS-line is observed which shows the signatures of extended localized states and emission characteristics close to that of the gold acceptor level in dislocation-free silicon. It is attributed to gold accumulated in the strain-field of dislocations. The amplitude of the C-line typically found in plastically deformed silicon shows no correlation with the gold concentration. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Thiosulfate leaching of gold from waste mobile phones.

    Science.gov (United States)

    Ha, Vinh Hung; Lee, Jae-chun; Jeong, Jinki; Hai, Huynh Trung; Jha, Manis K

    2010-06-15

    The present communication deals with the leaching of gold from the printed circuit boards (PCBs) of waste mobile phones using an effective and less hazardous system, i.e., a copper-ammonia-thiosulfate solution, as an alternative to the conventional and toxic cyanide leaching of gold. The influence of thiosulfate, ammonia and copper sulfate concentrations on the leaching of gold from PCBs of waste mobile phones was investigated. Gold extraction was found to be enhanced with solutions containing 15-20 mM cupric, 0.1-0.14 M thiosulfate, and 0.2-0.3 M ammonia. Similar trends were obtained for the leaching of gold from two different types of scraps and PCBs of waste mobile phones. From the scrap samples, 98% of the gold was leached out using a solution containing 20 mM copper, 0.12 M thiosulfate and 0.2 M ammonia. Similarly, the leaching of gold from the PCBs samples was also found to be good, but it was lower than that of scrap samples in similar experimental conditions. In this case, only 90% of the gold was leached, even with a contact time of 10h. The obtained data will be useful for the development of processes for the recycling of gold from waste mobile phones.

  10. Methanobactin-Mediated One-Step Synthesis of Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yan Wang

    2013-11-01

    Full Text Available Preparation of gold nanoparticles with a narrow size distribution has enormous importance in nanotechnology. Methanobactin (Mb is a copper-binding small peptide that appears to function as an agent for copper sequestration and uptake in methanotrophs. Mb can also bind and catalytically reduce Au (III to Au (0. In this study, we demonstrate a facile Mb-mediated one-step synthetic route to prepare monodispersed gold nanoparticles. Continuous reduction of Au (III by Mb can be achieved by using hydroquinone as the reducing agent. The gold nanoparticles have been characterized by UV-visible spectroscopy. The formation and the surface plasmon resonance properties of the gold nanoparticles are highly dependent on the ratio of Au (III to Mb in solution. X-ray photoelectron spectroscopy (XPS, fluorescence spectra and Fourier transform-infrared spectroscopy (FT-IR spectra suggest that Mb molecules catalytically reduce Au (III to Au (0 with the concomitant production of gold nanoparticles, and then, Mb statically adsorbed onto the surface of gold nanoparticles to form an Mb-gold nanoparticles assembly. This avoids secondary nucleation. The formed gold nanoparticles have been demonstrated to be monodispersed and uniform by transmission electron microscopy (TEM images. Analysis of these particles shows an average size of 14.9 nm with a standard deviation of 1.1 nm. The gold nanoparticles are extremely stable and can resist aggregation, even after several months.

  11. Dependence of in-tube doping on the radius and helicity of single-wall carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    刘红; 董锦明; 钱湄杶; 万贤纲

    2003-01-01

    Using the Lennard-Jones interaction potential between the impurity atom and carbon atom, we have studied the dependence of in-tube impurity doping on the radius of a single-wall carbon nanotube (SWNT), as well as its helicity.The obtained results show that the radius of the most stably doped SWNT is different for different kinds of impurity atoms. This is useful for producing the required doped SWNT. In addition, it is found that the helicity of tube has a strong effect on the potential energy of the atoms doped in the SWNT.

  12. Immobilization of gold nanoparticles on cell culture surfaces for safe and enhanced gold nanoparticle-mediated laser transfection

    Science.gov (United States)

    Kalies, Stefan; Heinemann, Dag; Schomaker, Markus; Gentemann, Lara; Meyer, Heiko; Ripken, Tammo

    2014-07-01

    In comparison to standard transfection methods, gold nanoparticle-mediated laser transfection has proven to be a versatile alternative. This is based on its minor influence on cell viability and its high efficiency, especially for the delivery of small molecules like small interfering RNA. However, in order to transfer it to routine usage, a safety aspect is of major concern: The avoidance of nanoparticle uptake by the cells is desired. The immobilization of the gold nanoparticles on cell culture surfaces can address this issue. In this study, we achieved this by silanization of the appropriate surfaces and the binding of gold nanoparticles to them. Comparable perforation efficiencies to the previous approaches of gold nanoparticle-mediated laser transfection with free gold nanoparticles are demonstrated. The uptake of the immobilized particles by the cells is unlikely. Consequently, these investigations offer the possibility of bringing gold nanoparticle-mediated laser transfection closer to routine usage.

  13. Immobilization of gold nanoparticles on cell culture surfaces for safe and enhanced gold nanoparticle-mediated laser transfection.

    Science.gov (United States)

    Kalies, Stefan; Heinemann, Dag; Schomaker, Markus; Gentemann, Lara; Meyer, Heiko; Ripken, Tammo

    2014-01-01

    In comparison to standard transfection methods, gold nanoparticle-mediated laser transfection has proven to be a versatile alternative. This is based on its minor influence on cell viability and its high efficiency, especially for the delivery of small molecules like small interfering RNA. However, in order to transfer it to routine usage, a safety aspect is of major concern: The avoidance of nanoparticle uptake by the cells is desired. The immobilization of the gold nanoparticles on cell culture surfaces can address this issue. In this study, we achieved this by silanization of the appropriate surfaces and the binding of gold nanoparticles to them. Comparable perforation efficiencies to the previous approaches of gold nanoparticle-mediated laser transfection with free gold nanoparticles are demonstrated. The uptake of the immobilized particles by the cells is unlikely. Consequently, these investigations offer the possibility of bringing gold nanoparticle-mediated laser transfection closer to routine usage.

  14. Fabrication and characterization of gold nanocrown arrays on a gold film for a high-sensitivity surface plasmon resonance biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Munsik; Kim, Nak-hyeon; Eom, Seyoung [Department of Biomedical Engineering, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Kim, Tae Woo [School of East–West Medical Science, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Byun, Kyung Min, E-mail: kmbyun@khu.ac.kr [Department of Biomedical Engineering, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Park, Hyeong-Ho, E-mail: hyeongho.park@kanc.re.kr [Nano Process Division, Korea Advanced Nano Fab Center, Suwon 443-270 (Korea, Republic of)

    2015-07-31

    We report on a versatile method to fabricate gold nanocrown arrays on a thin gold film based on ultraviolet nanoimprint lithography and tilted evaporation technique. We realize highly ordered 2-dimensional nanocrown arrays and characterize their sizes and morphologies using scanning electron microscopy. To demonstrate an enhanced surface plasmon resonance (SPR) detection by the fabricated gold nanocrown samples, biosensing experiments are performed by measuring SPR angle shift for biotin–streptavidin interaction and bulk refractive index change of dielectric medium. We hope that the suggested plasmonic platform with a high sensitivity could be extended to a variety of biomolecular binding reactions. - Highlights: • Gold nanocrown arrays are produced by nanoimprint lithography and tilted evaporation. • Use of gold nanocrown arrays can improve the sensor sensitivity significantly. • Improved sensitivity is due to enhanced field–matter interaction at gold nanocrowns.

  15. Cysteine-cystine redox cycling in a gold-gold dual-plate generator-collector microtrench sensor.

    Science.gov (United States)

    Hammond, Jules L; Gross, Andrew J; Estrela, Pedro; Iniesta, Jesus; Green, Stephen J; Winlove, C Peter; Winyard, Paul G; Benjamin, Nigel; Marken, Frank

    2014-07-15

    Thiols and disulfides are ubiquitous and important analytical targets. However, their redox properties, in particular on gold sensor electrodes, are complex and obscured by strong adsorption. Here, a gold-gold dual-plate microtrench dual-electrode sensor with feedback signal amplification is demonstrated to give well-defined (but kinetically limited) steady-state voltammetric current responses for the cysteine-cystine redox cycle in nondegassed aqueous buffer media at pH 7 down to micromolar concentration levels.

  16. Gold in the oceans through time

    Science.gov (United States)

    Large, Ross R.; Gregory, Daniel D.; Steadman, Jeffrey A.; Tomkins, Andrew G.; Lounejeva, Elena; Danyushevsky, Leonid V.; Halpin, Jacqueline A.; Maslennikov, Valeriy; Sack, Patrick J.; Mukherjee, Indrani; Berry, Ron; Hickman, Arthur

    2015-10-01

    During sedimentation and diagenesis of carbonaceous shales in marine continental margin settings, Au is adsorbed from seawater and organic matter and becomes incorporated into sedimentary pyrite. LA-ICPMS analysis of over 4000 sedimentary pyrite grains in 308 samples from 33 locations around the world, grouped over 123 determined ages, has enabled us to track, in a first order sense, the Au content of the ocean over the last 3.5 billion years. Gold was enriched in the Meso- and Neoarchean oceans, several times above present values, then dropped by an order of magnitude from the first Great Oxidation Event (GOE1) through the Paleoproterozoic to reach a minimum value around 1600 Ma. Gold content of the oceans then rose, with perturbations, through the Meso- and Neoproterozoic, showing a steady rise at the end of the Proterozoic (800 to 520 Ma), which most likely represents the effects of the second Great Oxidation Event (GOE2). Gold in the oceans was at a maximum at 520 Ma, when oxygen in the oceans rose to match current maximum values. In the Archean and Proterozoic, the Au content of seawater correlates with the time distribution of high-Mg greenstone belts, black shales and banded iron formations, suggesting that increases in atmospheric oxygen and marine bio-productivity, combined with the higher background of Au in komatiitic and Mg-rich basalts were the first order causes of the pattern of Au enrichment in seawater. We suggest the lack of major Au deposits from 1800 to 800 Ma, is explained by the low levels of Au in the oceans during this period.

  17. Amoxicillin functionalized gold nanoparticles reverts MRSA resistance

    Energy Technology Data Exchange (ETDEWEB)

    Kalita, Sanjeeb; Kandimalla, Raghuram; Sharma, Kaustav Kalyan [Drug Discovery Lab, Life Science Division, Institute of Advanced Study in Science and Technology (IASST), Paschim Boragaon, Garchuk, Guwahati 781035, Assam (India); Kataki, Amal Chandra [Dr. B. Borooah Cancer Institute, Guwahati, Assam (India); Department of Applied Sciences, Gopinath Bordoloi Nagar, Jalukbari, Gauhati University, Guwahati 781014, Assam (India); Deka, Manab [Department of Applied Sciences, Gopinath Bordoloi Nagar, Jalukbari, Gauhati University, Guwahati 781014, Assam (India); Kotoky, Jibon, E-mail: jkotoky@gmail.com [Drug Discovery Lab, Life Science Division, Institute of Advanced Study in Science and Technology (IASST), Paschim Boragaon, Garchuk, Guwahati 781035, Assam (India)

    2016-04-01

    In this study, we have described the biosynthesis of biocompatible gold nanoparticles (GNPs) from aqueous extract of the aerial parts of a pteridophyte, “Adiantum philippense” by microwave irradiation and its surface functionalization with broad spectrum beta lactam antibiotic, amoxicillin (Amox). The functionalization of amoxicillin on GNPs (GNP-Amox) was carried out via electrostatic interaction of protonated amino group and thioether moiety mediated attractive forces. The synthesized GNPs and GNP-Amox were physicochemically characterized. UV–Vis spectroscopy, Zeta potential, XRD, FTIR and SERS (surface enhanced raman spectra) results confirmed the loading of Amox into GNPs. Loading of Amox to GNPs reduce amoxicillin cytotoxicity, whereas GNPs were found to be nontoxic to mouse fibroblast cell line (L929) as evident from MTT and acridine orange/ethidium bromide (AO/EtBr) live/dead cell assays. The GNP-Amox conjugates demonstrated enhanced broad-spectrum bactericidal activity against both Gram-positive and Gram-negative bacteria. Furthermore, in-vitro and in-vivo assays of GNP-Amox revealed potent anti-MRSA activity and improved the survival rate. This indicates the subversion of antibiotic resistance mechanism by overcoming the effect of high levels of β-lactamase produced by methicillin resistant Staphylococcus aureus (MRSA). Taken together, this study demonstrates the positive attributes from GNP-Amox conjugates as a promising antibacterial therapeutic agent against MRSA as well as other pathogens. - Highlights: • Aqueous extract of A. phillippens was used as a reducing and capping agent for synthesis of microwave irradiated gold nanoparticles. • GNPs were loaded with amoxicillin for restoration in antibacterial activity of amoxicillin against MRSA strains. • Gold nanoparticles and GNP-Amox were found biocompitable as tested on L929 cell line. • The nanoparticle antibiotic conjugates exhibited restoration of amoxicillin activity against MRSA in

  18. Characterization of primary geochemical haloes for gold exploration at the Huanxiangwa gold deposit, China

    NARCIS (Netherlands)

    Wang, Changming; Carranza, Emmanuel John M.; Zhang, Shouting; Zhang, Jing; Liu, Xiaoji Liu; Zhang, Da; Sun, Xiang; Duan, Cunji

    2013-01-01

    Recognition of primary geochemical haloes is one of the most important tools for exploring undiscovered mineral resources. This tool is being routinely applied in exploration programs at the Huanxiangwa gold deposit, Xiong'er Mountains, China. Sampling of unweathered rock for multi-element analysis

  19. The Asian Games:How Much Gold is in the Gold Medals?

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    DESPITE China’s glorious victoryin Bangkok at the last AsianGames of this century,in whichthe Chinese team topped the list with129 gold medals,the Chinese athletesare asked to keep their fingers crossedfor the Olympic Games.After a briefrest,the Chinese athletes have returnedto their training ground in preparationfor the fiercer competition at the 2000

  20. Bioleaching of refractory gold ore (Ⅲ)--Fluid leaching Jinya refractory gold concentrate by Thiobacillus ferrooxidans

    Institute of Scientific and Technical Information of China (English)

    闵小波; 柴立元; 陈为亮; 于霞; 张传福; 邝中

    2002-01-01

    A novel fluidized-bed reactor was designed and installed for bioleaching in a semi-continuous way,by which a process for bioleaching-cyanidation of Jinya refractory gold arsenical concentrate was studied.The arsenic extraction rate reaches 82.5% after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0,ferric ion concentration 6.5 g/L and pulp concentration 10%.And leached rate of gold in the following cyanidation is over 90%.The parameters of three series fluidized-bed reactors exhibit stability during the semi-continuous bioleaching of the concentrate.Arsenic in the concentrate can be got rid of 91% after 6-day leaching.Even after 4 days,82% of arsenic extraction rate was still obtained.The recovery rates of gold are 92% and 87.5% respectively in cyaniding the above bioleached residues.The results will provide a base for further commercial production of gold development.