A framework for automatic creation of gold-standard rigid 3D-2D registration datasets.

Science.gov (United States)

Madan, Hennadii; Pernuš, Franjo; Likar, Boštjan; Špiclin, Žiga

2017-02-01

Advanced image-guided medical procedures incorporate 2D intra-interventional information into pre-interventional 3D image and plan of the procedure through 3D/2D image registration (32R). To enter clinical use, and even for publication purposes, novel and existing 32R methods have to be rigorously validated. The performance of a 32R method can be estimated by comparing it to an accurate reference or gold standard method (usually based on fiducial markers) on the same set of images (gold standard dataset). Objective validation and comparison of methods are possible only if evaluation methodology is standardized, and the gold standard  dataset is made publicly available. Currently, very few such datasets exist and only one contains images of multiple patients acquired during a procedure. To encourage the creation of gold standard 32R datasets, we propose an automatic framework. The framework is based on rigid registration of fiducial markers. The main novelty is spatial grouping of fiducial markers on the carrier device, which enables automatic marker localization and identification across the 3D and 2D images. The proposed framework was demonstrated on clinical angiograms of 20 patients. Rigid 32R computed by the framework was more accurate than that obtained manually, with the respective target registration error below 0.027 mm compared to 0.040 mm. The framework is applicable for gold standard setup on any rigid anatomy, provided that the acquired images contain spatially grouped fiducial markers. The gold standard datasets and software will be made publicly available.

Low friction arthroplasty and dual mobility cup: a new gold standard.

Science.gov (United States)

Prudhon, Jean Louis; Verdier, Régis; Caton, Jacques H

2017-03-01

Low friction arthroplasty (LFA) introduced by Sir John Charnley was the gold standard for many years. Dislocation and infection are the first causes for early revision. Late failures are polyethylene (PE) wear and loosening. Due to dislocation risk we slowly switched to the use of LFA with dual mobility cups (DMC). The purposes of this study are (1) to assess whether our changes have improved outcomes and (2) what is the new gold standard? We selected from an observational registry of 1,091 cases of hybrid Charnley total hip arthroplasty (THA). The acetabular component was either DMC in 455 cases or fixed cup (FC) in 636 cases. Three dislocations (0.6%) occurred in the DMC group (none revised). In the FC group 54 dislocated (8.49%) and 20 were recurrent and underwent revision (revision rate 3.14%). In the DMC group, five acetabular and three femoral revisions were performed (revision rate for loosening 1.7%). In the FC group 19 cases underwent acetabular revision, and five cases had femoral component revised (revision rate for loosening 3.7%). Charnley's LFA has proven over 50 years of excellent survivorship. To decrease dislocation risk, one suggested increasing femoral head diameter. Gilles Bousquet proposed another way, namely, the DMC concept. Dislocation is no longer a critical issue with DMC as demonstrated in our series and main series. DMC in primary THA is still a subject of debate. Mid-term results do not demonstrate a higher rate of wear than LFA. What is the current gold standard? LFA was and is our current gold standard in association with a DMC.

Democratic Constraints and Adherence to the Classical Gold Standard

NARCIS (Netherlands)

Kramer, Bert S.; Milionis, Petros

We study how domestic politics affected the decisions of countries to adhere to the classical gold standard. Using a variety of econometric techniques and controlling for a wide range of economic factors, we demonstrate that political constraints were important in the decision of countries to adopt

The gold standard: gold nanoparticle libraries to understand the nano-bio interface.

Science.gov (United States)

Alkilany, Alaaldin M; Lohse, Samuel E; Murphy, Catherine J

2013-03-19

Since the late 1980s, researchers have prepared inorganic nanoparticles of many types--including elemental metals, metal oxides, metal sulfides, metal selenides, and metal tellurides--with excellent control over size and shape. Originally many researchers were primarily interested in exploring the quantum size effects predicted for such materials. Applications of inorganic nanomaterials initially centered on physics, optics, and engineering but have expanded to include biology. Many current nanomaterials can serve as biochemical sensors, contrast agents in cellular or tissue imaging, drug delivery vehicles, or even as therapeutics. In this Account we emphasize that the understanding of how nanomaterials will function in a biological system relies on the knowledge of the interface between biological systems and nanomaterials, the nano-bio interface. Gold nanoparticles can serve as excellent standards to understand more general features of the nano-bio interface because of its many advantages over other inorganic materials. The bulk material is chemically inert, and well-established synthetic methods allow researchers to control its size, shape, and surface chemistry. Gold's background concentration in biological systems is low, which makes it relatively easy to measure it at the part-per-billion level or lower in water. In addition, the large electron density of gold enables relatively simple electron microscopic experiments to localize it within thin sections of cells or tissue. Finally, gold's brilliant optical properties at the nanoscale are tunable with size, shape, and aggregation state and enable many of the promising chemical sensing, imaging, and therapeutic applications. Basic experiments with gold nanoparticles and cells include measuring the toxicity of the particles to cells in in vitro experiments. The species other than gold in the nanoparticle solution can be responsible for the apparent toxicity at a particular dose. Once the identity of the toxic

Effectiveness of the Gold Standard Programme compared with other smoking cessation interventions in Denmark

DEFF Research Database (Denmark)

Rasmussen, Mette; Fernández, Esteve; Tønnesen, Hanne

2017-01-01

Objectives: We compared the effectiveness of the Gold Standard Programme (a comprehensive smoking cessation intervention commonly used in Denmark) with other face-to-face smoking cessation programmes in Denmark after implementation in real life, and we identified factors associated with successful...... did not want further contact, who intentionally were not followed up or who lacked information about the intervention they received were excluded. A total of 46 287 smokers were included. Interventions: Various real-life smoking cessation interventions were identified and compared: The Gold Standard...... smokers. The follow-up rate was 74%. Women were less likely to remain abstinent, OR 0.83 (CI 0.79 to 0.87). Short interventions were more effective among men. After adjusting for confounders, the Gold Standard Programme was the only intervention with significant results across sex, increasing the odds...

Gold-standard for computer-assisted morphological sperm analysis.

Science.gov (United States)

Chang, Violeta; Garcia, Alejandra; Hitschfeld, Nancy; Härtel, Steffen

2017-04-01

Published algorithms for classification of human sperm heads are based on relatively small image databases that are not open to the public, and thus no direct comparison is available for competing methods. We describe a gold-standard for morphological sperm analysis (SCIAN-MorphoSpermGS), a dataset of sperm head images with expert-classification labels in one of the following classes: normal, tapered, pyriform, small or amorphous. This gold-standard is for evaluating and comparing known techniques and future improvements to present approaches for classification of human sperm heads for semen analysis. Although this paper does not provide a computational tool for morphological sperm analysis, we present a set of experiments for comparing sperm head description and classification common techniques. This classification base-line is aimed to be used as a reference for future improvements to present approaches for human sperm head classification. The gold-standard provides a label for each sperm head, which is achieved by majority voting among experts. The classification base-line compares four supervised learning methods (1- Nearest Neighbor, naive Bayes, decision trees and Support Vector Machine (SVM)) and three shape-based descriptors (Hu moments, Zernike moments and Fourier descriptors), reporting the accuracy and the true positive rate for each experiment. We used Fleiss' Kappa Coefficient to evaluate the inter-expert agreement and Fisher's exact test for inter-expert variability and statistical significant differences between descriptors and learning techniques. Our results confirm the high degree of inter-expert variability in the morphological sperm analysis. Regarding the classification base line, we show that none of the standard descriptors or classification approaches is best suitable for tackling the problem of sperm head classification. We discovered that the correct classification rate was highly variable when trying to discriminate among non-normal sperm

The Trouble with the Gold Standard: School Libraries & Research

Science.gov (United States)

Gordon, Carol

2007-01-01

Although science has provided empirical evidence for centuries, it's only as recently as the 1940s that a scientific method called randomized controlled trials (RCT) emerged as a technique to test the efficacy of drugs and medical procedures. Since RCT is unique in that it can claim causality, it's considered the "gold standard" of research…

Postcholecystectomy benign biliary stricture: Surgery is the gold standard

Directory of Open Access Journals (Sweden)

Sadiq S Sikora

2012-01-01

Full Text Available Post cholecystectomy bile duct strictures present a challenge to the treating physicians. Advancement in skills and technology offers alternative treatment modalities to the standard surgical repair. Contemporary series of surgical repair by experienced surgeons report excellent long-term results with <5% restricture rates. Endoscopic therapy is conceptually flawed, is not applicable to all patients, requires prolonged duration of treatment with multiple interventions. Surgical repair by an experienced surgeon is the "Gold Standard" of care in management of postcholecystectomy bile duct strictures.

Building a gold standard to construct search filters: a case study with biomarkers for oral cancer.

Science.gov (United States)

Frazier, John J; Stein, Corey D; Tseytlin, Eugene; Bekhuis, Tanja

2015-01-01

To support clinical researchers, librarians and informationists may need search filters for particular tasks. Development of filters typically depends on a "gold standard" dataset. This paper describes generalizable methods for creating a gold standard to support future filter development and evaluation using oral squamous cell carcinoma (OSCC) as a case study. OSCC is the most common malignancy affecting the oral cavity. Investigation of biomarkers with potential prognostic utility is an active area of research in OSCC. The methods discussed here should be useful for designing quality search filters in similar domains. The authors searched MEDLINE for prognostic studies of OSCC, developed annotation guidelines for screeners, ran three calibration trials before annotating the remaining body of citations, and measured inter-annotator agreement (IAA). We retrieved 1,818 citations. After calibration, we screened the remaining citations (n = 1,767; 97.2%); IAA was substantial (kappa = 0.76). The dataset has 497 (27.3%) citations representing OSCC studies of potential prognostic biomarkers. The gold standard dataset is likely to be high quality and useful for future development and evaluation of filters for OSCC studies of potential prognostic biomarkers. The methodology we used is generalizable to other domains requiring a reference standard to evaluate the performance of search filters. A gold standard is essential because the labels regarding relevance enable computation of diagnostic metrics, such as sensitivity and specificity. Librarians and informationists with data analysis skills could contribute to developing gold standard datasets and subsequent filters tuned for their patrons' domains of interest.

Partial verification bias and incorporation bias affected accuracy estimates of diagnostic studies for biomarkers that were part of an existing composite gold standard.

Science.gov (United States)

Karch, Annika; Koch, Armin; Zapf, Antonia; Zerr, Inga; Karch, André

2016-10-01

To investigate how choice of gold standard biases estimates of sensitivity and specificity in studies reassessing the diagnostic accuracy of biomarkers that are already part of a lifetime composite gold standard (CGS). We performed a simulation study based on the real-life example of the biomarker "protein 14-3-3" used for diagnosing Creutzfeldt-Jakob disease. Three different types of gold standard were compared: perfect gold standard "autopsy" (available in a small fraction only; prone to partial verification bias), lifetime CGS (including the biomarker under investigation; prone to incorporation bias), and "best available" gold standard (autopsy if available, otherwise CGS). Sensitivity was unbiased when comparing 14-3-3 with autopsy but overestimated when using CGS or "best available" gold standard. Specificity of 14-3-3 was underestimated in scenarios comparing 14-3-3 with autopsy (up to 24%). In contrast, overestimation (up to 20%) was observed for specificity compared with CGS; this could be reduced to 0-10% when using the "best available" gold standard. Choice of gold standard affects considerably estimates of diagnostic accuracy. Using the "best available" gold standard (autopsy where available, otherwise CGS) leads to valid estimates of specificity, whereas sensitivity is estimated best when tested against autopsy alone. Copyright © 2016 Elsevier Inc. All rights reserved.

Determination of gold and silver in geological standard samples MGI by instrument neutron activation analysis

International Nuclear Information System (INIS)

Lu Huijiuan; Zhou; Yunlu

1987-01-01

Gold and silver in geological standard samples MGI were determined by instrument neutron activation analysis. The various interferences of nuclides were considered. Corrected factors of the geometry in different positions have been determined. Using the geological standard sample MGM and radiochemical separation neutron activation method as reference, the reliability of this method is proved. Gold content in samples is 0.4-0.009 g/t, silver content is 9-0.3 g/t. Standard deviation is less than 3.5%, the precision of the measurement is 4.8-11.6%

A multilingual gold-standard corpus for biomedical concept recognition: the Mantra GSC.

Science.gov (United States)

Kors, Jan A; Clematide, Simon; Akhondi, Saber A; van Mulligen, Erik M; Rebholz-Schuhmann, Dietrich

2015-09-01

To create a multilingual gold-standard corpus for biomedical concept recognition. We selected text units from different parallel corpora (Medline abstract titles, drug labels, biomedical patent claims) in English, French, German, Spanish, and Dutch. Three annotators per language independently annotated the biomedical concepts, based on a subset of the Unified Medical Language System and covering a wide range of semantic groups. To reduce the annotation workload, automatically generated preannotations were provided. Individual annotations were automatically harmonized and then adjudicated, and cross-language consistency checks were carried out to arrive at the final annotations. The number of final annotations was 5530. Inter-annotator agreement scores indicate good agreement (median F-score 0.79), and are similar to those between individual annotators and the gold standard. The automatically generated harmonized annotation set for each language performed equally well as the best annotator for that language. The use of automatic preannotations, harmonized annotations, and parallel corpora helped to keep the manual annotation efforts manageable. The inter-annotator agreement scores provide a reference standard for gauging the performance of automatic annotation techniques. To our knowledge, this is the first gold-standard corpus for biomedical concept recognition in languages other than English. Other distinguishing features are the wide variety of semantic groups that are being covered, and the diversity of text genres that were annotated. © The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association.

Assessing validity of a depression screening instrument in the absence of a gold standard.

Science.gov (United States)

Gelaye, Bizu; Tadesse, Mahlet G; Williams, Michelle A; Fann, Jesse R; Vander Stoep, Ann; Andrew Zhou, Xiao-Hua

2014-07-01

We evaluated the extent to which use of a hypothesized imperfect gold standard, the Composite International Diagnostic Interview (CIDI), biases the estimates of diagnostic accuracy of the Patient Health Questionnaire-9 (PHQ-9). We also evaluate how statistical correction can be used to address this bias. The study was conducted among 926 adults where structured interviews were conducted to collect information about participants' current major depressive disorder using PHQ-9 and CIDI instruments. First, we evaluated the relative psychometric properties of PHQ-9 using CIDI as a gold standard. Next, we used a Bayesian latent class model to correct for the bias. In comparison with CIDI, the relative sensitivity and specificity of the PHQ-9 for detecting major depressive disorder at a cut point of 10 or more were 53.1% (95% confidence interval: 45.4%-60.8%) and 77.5% (95% confidence interval, 74.5%-80.5%), respectively. Using a Bayesian latent class model to correct for the bias arising from the use of an imperfect gold standard increased the sensitivity and specificity of PHQ-9 to 79.8% (95% Bayesian credible interval, 64.9%-90.8%) and 79.1% (95% Bayesian credible interval, 74.7%-83.7%), respectively. Our results provided evidence that assessing diagnostic validity of mental health screening instrument, where application of a gold standard might not be available, can be accomplished by using appropriate statistical methods. Copyright © 2014 Elsevier Inc. All rights reserved.

Comparison of EHR-based diagnosis documentation locations to a gold standard for risk stratification in patients with multiple chronic conditions.

Science.gov (United States)

Martin, Shelby; Wagner, Jesse; Lupulescu-Mann, Nicoleta; Ramsey, Katrina; Cohen, Aaron; Graven, Peter; Weiskopf, Nicole G; Dorr, David A

2017-08-02

To measure variation among four different Electronic Health Record (EHR) system documentation locations versus 'gold standard' manual chart review for risk stratification in patients with multiple chronic illnesses. Adults seen in primary care with EHR evidence of at least one of 13 conditions were included. EHRs were manually reviewed to determine presence of active diagnoses, and risk scores were calculated using three different methodologies and five EHR documentation locations. Claims data were used to assess cost and utilization for the following year. Descriptive and diagnostic statistics were calculated for each EHR location. Criterion validity testing compared the gold standard verified diagnoses versus other EHR locations and risk scores in predicting future cost and utilization. Nine hundred patients had 2,179 probable diagnoses. About 70% of the diagnoses from the EHR were verified by gold standard. For a subset of patients having baseline and prediction year data (n=750), modeling showed that the gold standard was the best predictor of outcomes on average for a subset of patients that had these data. However, combining all data sources together had nearly equivalent performance for prediction as the gold standard. EHR data locations were inaccurate 30% of the time, leading to improvement in overall modeling from a gold standard from chart review for individual diagnoses. However, the impact on identification of the highest risk patients was minor, and combining data from different EHR locations was equivalent to gold standard performance. The reviewer's ability to identify a diagnosis as correct was influenced by a variety of factors, including completeness, temporality, and perceived accuracy of chart data.

75 FR 28227 - National Emission Standards for Hazardous Air Pollutants: Gold Mine Ore Processing and Production...

Science.gov (United States)

2010-05-20

...-AP48 National Emission Standards for Hazardous Air Pollutants: Gold Mine Ore Processing and Production... published a proposed rule for mercury emissions from the gold mine ore processing and production area source... Environmental protection, Air pollution control, Hazardous substances, Incorporations by reference, Reporting...

Does the Gold Standard label hold its promise in delivering higher Sustainable Development benefits? A multi-criteria comparison of CDM projects

International Nuclear Information System (INIS)

Drupp, Moritz A.

2011-01-01

The Clean Development Mechanism (CDM) has a twin objective: to help developed countries reduce GHG emissions, and to support developing countries in achieving Sustainable Development (SD). As a response to the widespread criticism of the CDM's unsatisfactory SD record, initiatives have developed premium labels like the Gold Standard, which applies two additional 'screens' to filter CDM projects for higher SD benefits. In order to determine whether Gold Standard projects can be associated with higher local SD benefits, this paper evaluates the potential benefits of 48 CDM projects using a multi-criteria method and building on existing work. The 18 evaluated Gold Standard projects are compared to a 'representative portfolio' of 30 unlabeled CDM projects in order to capture the 'full' effect of the additional Gold Standard requirements, which is further decomposed into the two 'screen' effects. The results suggest that Gold Standard Certified Emission Reductions can be associated with higher potential local SD benefits when compared to the 'representative portfolio' of unlabeled CDM projects, while the comparison of projects of the same type remains inconclusive. The results support previous findings showing that renewable energy projects may deliver comparatively high SD benefits. - Research highlights: → This study evaluates and compares the potential contribution of unlabeled- and Gold Standard labeled CDM projects to Sustainable Development (SD), extending the previously assessed projects as well as the methodological approach. → Gold Standard labeled Certified Emission Reductions (CER) can be associated with higher potential SD benefits compared to unlabeled projects. → A decomposition analysis shows that the Gold Standard s SD surplus must be primarily attributed to the favorable contribution of renewable energy projects to SD. → Policy makers might thus shift incentives towards renewable energy projects and buyers of CERs may shift their offset

Gold-195m for studies on regional pulmonary circulation

International Nuclear Information System (INIS)

Eriksson, L.; Andersson, L.; Jonson, B.; Westling, H.; White, T.; Wollmer, P.

1985-01-01

Six healthy controls, seven patients with coronary heart disease (CHD), and five patients with exercise-induced asthma (EIA) were studied in the sitting position at rest and during maximum exercise. The radionuclide gold-195m was used in the studies. A redistribution of activity toward the lung apex was found during exercise, the change being more pronounced in the healthy controls than in the patients with CHD. In two of the three patients in which exercise induced an asthmatic attack, gross reductions in the activity were seen in different areas of the lung. The authors conclude that gold-195m can be used for studies of rapid changes in regional pulmonary circulation

Usage of Latent Class Analysis in Diagnostic Microbiology in the Absence of Gold Standard Test

Directory of Open Access Journals (Sweden)

Gul Bayram Abiha

2016-12-01

Full Text Available The evaluation of performance of various tests diagnostic tests in the absence of gold standard is an important problem. Latent class analysis (LCA is a statistical analysis method known for many years, especially in the absence of a gold standard for evaluation of diagnostic tests so that LCA has found its wide application area. During the last decade, LCA method has widely used in for determining sensivity and specifity of different microbiological tests. It has investigated in the diagnosis of mycobacterium tuberculosis, mycobacterium bovis, human papilloma virus, bordetella pertussis, influenza viruses, hepatitis E virus (HEV, hepatitis C virus (HCV and other various viral infections. Researchers have compared several diagnostic tests for the diagnosis of different pathogens with LCA. We aimed to evaluate performance of latent class analysis method used microbiological diagnosis in various diseases in several researches. When we took into account all of these tests' results, we suppose that LCA is a good statistical analysis method to assess different test performances in the absence of gold standard. [Archives Medical Review Journal 2016; 25(4.000: 467-488

Validating Automated Essay Scoring: A (Modest) Refinement of the "Gold Standard"

Science.gov (United States)

Powers, Donald E.; Escoffery, David S.; Duchnowski, Matthew P.

2015-01-01

By far, the most frequently used method of validating (the interpretation and use of) automated essay scores has been to compare them with scores awarded by human raters. Although this practice is questionable, human-machine agreement is still often regarded as the "gold standard." Our objective was to refine this model and apply it to…

Carbon finance and pro-poor co-benefits: The Gold Standard and Climate, Community and Biodiversity Standards

Energy Technology Data Exchange (ETDEWEB)

Wood, Rachel

2011-04-15

This paper assesses the practical contribution of the Gold Standard (GS) and Climate Community and Biodiversity (CCB) Standards to local development through the identification of high quality carbon offset projects and ensuring high standards of consultation with local communities during project development and implementation. It is based on desk research, involving analysis of the GS and CCB Standards' project databases, project design documents, and secondary literature. In addition, over 20 representatives of the two standards systems, project developers, NGO representatives, and researchers were interviewed. The paper concludes that both standard systems successfully reward high quality projects which have a demonstrated commitment to local consultations and sustainable development benefits. Moreover, they serve to give well-meaning project developers frameworks with which to ensure that a wide range of criteria are considered in planning and implementing projects. As voluntary standards, it is unrealistic to expect either the GS or CCB Standards to improve poor-quality or unsustainable projects.

Carbon finance and pro-poor co-benefits: The Gold Standard and Climate, Community and Biodiversity Standards

Energy Technology Data Exchange (ETDEWEB)

Wood, Rachel

2011-04-15

This paper assesses the practical contribution of the Gold Standard (GS) and Climate Community and Biodiversity (CCB) Standards to local development through the identification of high quality carbon offset projects and ensuring high standards of consultation with local communities during project development and implementation. It is based on desk research, involving analysis of the GS and CCB Standards' project databases, project design documents, and secondary literature. In addition, over 20 representatives of the two standards systems, project developers, NGO representatives, and researchers were interviewed. The paper concludes that both standard systems successfully reward high quality projects which have a demonstrated commitment to local consultations and sustainable development benefits. Moreover, they serve to give well-meaning project developers frameworks with which to ensure that a wide range of criteria are considered in planning and implementing projects. As voluntary standards, it is unrealistic to expect either the GS or CCB Standards to improve poor-quality or unsustainable projects.

International Reserves Crises, Monetary Integration and the Payments System during the International Gold Standard

OpenAIRE

Paula Hernandez-Verme

2009-01-01

I model an international payments system with a financial center and periphery to reproduce various aspects of the International Gold Standard. This period was characterized by frequent crises associated with scarce stocks of reserves, high short-term interest rates with subsequent gold inflows and transmission of output contractions across countries. I find that a common international currency and no legal restrictions on exchange help the periphery share reserves with the financial center, ...

Region-selective electroless gold plating on polycarbonate sheets by UV-patterning in combination with silver activating

Energy Technology Data Exchange (ETDEWEB)

Zhou Qinghua [Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Zijin' gang Campus, Hangzhou 310058 (China); Chen Hengwu, E-mail: hwchen@zju.edu.c [Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Zijin' gang Campus, Hangzhou 310058 (China); Wang Yi [Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Zijin' gang Campus, Hangzhou 310058 (China)

2010-02-28

A simple, time- and cost-effective approach for region-selective metalization of polycarbonate (PC) surface has been established by combining photoresist-free UV-patterning with tin- and amine-free silver activating and electroless gold plating. The surface of PC sheets was exposed to the UV lights emitted from a low-pressure mercury lamp through a photomask, the micro pattern on the mask being transferred to the PC surface due to the photochemical generation of carboxyl groups on the UV-exposed region. The UV-exposed PC sheets were then treated with an ammoniacal AgNO{sub 3} solution, so that the silver ions were chemisorbed by the photochemically generated carboxyl groups. When the Ag{sup +}-adsorbed PC sheet was immersed into an electroless gold plating bath, shiny gold film quickly deposited on the UV-exposed region, resulting in the formation of a micro gold devices on the PC surface. The whole plating process including UV-exposure, surface activating and gold plating can be completed in about 3-4 h. Attenuated total reflection Fourier transformation infrared spectrometer (ATR-FT-IR), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and scanning electron microscope (SEM) were employed to trace the surface change during the plating process. Cyclic voltammetry (CV) and Scotch-tape test were employed to characterize the electrochemical properties and adhesion strength of the prepared micro gold devices, respectively. The prepared micro gold electrodes were demonstrated for amperometric detection of hydrogen peroxide.

Use of gold and silver standards based on phenol-formalde-hyde resin in assay-activation analysis of geological samples

International Nuclear Information System (INIS)

Aliev, A.I.; Drynkin, V.I.; Lejpunskaya, D.I.; Nedostup, T.V.

1976-01-01

Using standards on phenol-formaldehyde resin base for assaying-activation analysis of geological specimens for gold and silver has bee the advantage of uniformly distributing Au and Ag in spesimens and possible preparing tablets of practically any form or size. The validity and accuracy of these standards have been studied for the cases of short irradiation. Conventional point standards were used as reference standards. The experiments carried out have shown that tablet resol standards are suitable for a mass assaying-activation analysis for gold and silver at practically any concentrations

Seeking a Valid Gold Standard for an Innovative, Dialect-Neutral Language Test

Science.gov (United States)

Pearson, Barbara Zurer; Jackson, Janice E.; Wu, Haotian

2014-01-01

Purpose: In this study, the authors explored alternative gold standards to validate an innovative, dialect-neutral language assessment. Method: Participants were 78 African American children, ages 5;0 (years;months) to 6;11. Twenty participants had previously been identified as having language impairment. The Diagnostic Evaluation of Language…

Population Health Metrics Research Consortium gold standard verbal autopsy validation study: design, implementation, and development of analysis datasets

Directory of Open Access Journals (Sweden)

Ohno Summer

2011-08-01

Full Text Available Abstract Background Verbal autopsy methods are critically important for evaluating the leading causes of death in populations without adequate vital registration systems. With a myriad of analytical and data collection approaches, it is essential to create a high quality validation dataset from different populations to evaluate comparative method performance and make recommendations for future verbal autopsy implementation. This study was undertaken to compile a set of strictly defined gold standard deaths for which verbal autopsies were collected to validate the accuracy of different methods of verbal autopsy cause of death assignment. Methods Data collection was implemented in six sites in four countries: Andhra Pradesh, India; Bohol, Philippines; Dar es Salaam, Tanzania; Mexico City, Mexico; Pemba Island, Tanzania; and Uttar Pradesh, India. The Population Health Metrics Research Consortium (PHMRC developed stringent diagnostic criteria including laboratory, pathology, and medical imaging findings to identify gold standard deaths in health facilities as well as an enhanced verbal autopsy instrument based on World Health Organization (WHO standards. A cause list was constructed based on the WHO Global Burden of Disease estimates of the leading causes of death, potential to identify unique signs and symptoms, and the likely existence of sufficient medical technology to ascertain gold standard cases. Blinded verbal autopsies were collected on all gold standard deaths. Results Over 12,000 verbal autopsies on deaths with gold standard diagnoses were collected (7,836 adults, 2,075 children, 1,629 neonates, and 1,002 stillbirths. Difficulties in finding sufficient cases to meet gold standard criteria as well as problems with misclassification for certain causes meant that the target list of causes for analysis was reduced to 34 for adults, 21 for children, and 10 for neonates, excluding stillbirths. To ensure strict independence for the validation of

Human papillomavirus testing as a cytology gold standard : comparing Surinam with the Netherlands

NARCIS (Netherlands)

Wachtel, MS; Boon, ME; Korporaal, H; Kok, LP

Polymerase chain reaction to detect high- risk human papillomavirus has been suggested as a gold standard for cytology. The Netherlands and Surinam were prospectively compared in regard to the proportions of Negative, Atypical Squamous Cells of Undetermined Significance, and Squamous Intraepithelial

Reassessing RCTs as the "Gold Standard": Synergy Not Separatism in Evaluation Designs

Science.gov (United States)

Hanley, Pam; Chambers, Bette; Haslam, Jonathan

2016-01-01

Randomised controlled trials (RCTs) are increasingly used to evaluate educational interventions in the UK. However, RCTs remain controversial for some elements of the research community. This paper argues that the widespread use of the term "gold standard" to describe RCTs is problematic, as it implies that other research methods are…

De-identifying Swedish clinical text - refinement of a gold standard and experiments with Conditional random fields

Directory of Open Access Journals (Sweden)

Dalianis Hercules

2010-04-01

Full Text Available Abstract Background In order to perform research on the information contained in Electronic Patient Records (EPRs, access to the data itself is needed. This is often very difficult due to confidentiality regulations. The data sets need to be fully de-identified before they can be distributed to researchers. De-identification is a difficult task where the definitions of annotation classes are not self-evident. Results We present work on the creation of two refined variants of a manually annotated Gold standard for de-identification, one created automatically, and one created through discussions among the annotators. The data is a subset from the Stockholm EPR Corpus, a data set available within our research group. These are used for the training and evaluation of an automatic system based on the Conditional Random Fields algorithm. Evaluating with four-fold cross-validation on sets of around 4-6 000 annotation instances, we obtained very promising results for both Gold Standards: F-score around 0.80 for a number of experiments, with higher results for certain annotation classes. Moreover, 49 false positives that were verified true positives were found by the system but missed by the annotators. Conclusions Our intention is to make this Gold standard, The Stockholm EPR PHI Corpus, available to other research groups in the future. Despite being slightly more time-consuming we believe the manual consensus gold standard is the most valuable for further research. We also propose a set of annotation classes to be used for similar de-identification tasks.

After the Gold Rush: Questioning the "Gold Standard" and Reappraising the Status of Experiment and Randomized Controlled Trials in Education

Science.gov (United States)

Thomas, Gary

2016-01-01

The past few years have seen a resurgence of faith in experimentation in education inquiry, and particularly in randomized controlled trials (RCTs). Proponents of such research have succeeded in bringing into common parlance the term "gold standard," which suggests that research emerging from any other design frame fails to achieve the…

Gold Returns

OpenAIRE

Robert J. Barro; Sanjay P. Misra

2013-01-01

From 1836 to 2011, the average real rate of price change for gold in the United States is 1.1% per year and the standard deviation is 13.1%, implying a one-standard-deviation confidence band for the mean of (0.1%, 2.1%). The covariances of gold's real rate of price change with consumption and GDP growth rates are small and statistically insignificantly different from zero. These negligible covariances suggest that gold's expected real rate of return--which includes an unobserved dividend yiel...

PIXE studies on gold standards by protons of energy 3.3 Me V

International Nuclear Information System (INIS)

Joseph, Daisy; Saxena, A.; Gupta, S.K.; Kailas, S.

2005-01-01

Proton Induced X-ray Emission Technique (PIXE) has been used in analysing Gold standards of 22, 20, 18, and 14 karats with a proton beam of energy 3.3 MeV at the newly commissioned Folded Tandem Ion Accelerator (FOTIA). Well resolved Au and Ag X-rays were detected at a current of 3 nA. Percentage values of gold and silver were calculated and were checked with those obtained by Energy Dispersive X-ray Fluorescence Method and were found to be in agreement with the certified values as well as those obtained by XRF. (author)

Gold monetization and gold discipline

OpenAIRE

Robert P. Flood; Peter M. Garber

1981-01-01

The paper is a study of the price level and relative price effects of a policy to monetize gold and fix its price at a given future time and at the then prevailing nominal price. Price movements are analyzed both during the transition to the gold standard and during the post-monetization period. The paper also explores the adjustments to fiat money which are necessary to ensure that this type of gold monetization is non-inflationary. Finally, some conditions which produce a run on the governm...

A studentized permutation test for three-arm trials in the 'gold standard' design.

Science.gov (United States)

Mütze, Tobias; Konietschke, Frank; Munk, Axel; Friede, Tim

2017-03-15

The 'gold standard' design for three-arm trials refers to trials with an active control and a placebo control in addition to the experimental treatment group. This trial design is recommended when being ethically justifiable and it allows the simultaneous comparison of experimental treatment, active control, and placebo. Parametric testing methods have been studied plentifully over the past years. However, these methods often tend to be liberal or conservative when distributional assumptions are not met particularly with small sample sizes. In this article, we introduce a studentized permutation test for testing non-inferiority and superiority of the experimental treatment compared with the active control in three-arm trials in the 'gold standard' design. The performance of the studentized permutation test for finite sample sizes is assessed in a Monte Carlo simulation study under various parameter constellations. Emphasis is put on whether the studentized permutation test meets the target significance level. For comparison purposes, commonly used Wald-type tests, which do not make any distributional assumptions, are included in the simulation study. The simulation study shows that the presented studentized permutation test for assessing non-inferiority in three-arm trials in the 'gold standard' design outperforms its competitors, for instance the test based on a quasi-Poisson model, for count data. The methods discussed in this paper are implemented in the R package ThreeArmedTrials which is available on the comprehensive R archive network (CRAN). Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Evaluation of the accuracy of diagnostic scales for a syndrome in Chinese medicine in the absence of a gold standard.

Science.gov (United States)

Wang, Xiao Nan; Zhou, Vanessa; Liu, Qiang; Gao, Ying; Zhou, Xiao-Hua

2016-01-01

The concept of syndromes (zhengs) is unique to Chinese medicine (CM) and difficult to measure. Expert consensus is used as a gold standard to identify zhengs and evaluate the accuracy of existing diagnostic scales for zhengs. But, the use of expert consensus as a gold standard is problematic because the diagnosis of zhengs by expert consensus is not 100 % accurate. This study aimed to evaluate the accuracy of standardized diagnostic scales for a syndrome zhengs in the absence of a gold standard, with application to internal wind (nei feng) syndrome in ischemic stroke patients. A total of 204 participants (age 41-84 years) with ischemic stroke were assessed by the stroke syndrome differentiation diagnostic criterion (SSDC), ischemic stroke TCM syndrome diagnostic scale (ISDS), and expert syndrome differentiation (ESD). The diagnostic tests and data collection process were conducted over a 10-month period (February 2008 to November 2008) in 10 hospitals across nine cities in China. The Bayesian method was used to estimate the accuracy of the SSDC, ISDS, and ESD. For internal wind syndrome, the estimated sensitivities and specificities of the SSDC, ISDS, and ESD without use of a gold standard were respectively: [Formula: see text], [Formula: see text]; [Formula: see text], [Formula: see text]; and [Formula: see text], [Formula: see text]. After adjusting for imperfect gold standard bias, we found that both the sensitivity and specificity of the ISDS were higher than those of the SSDC for diagnosis of internal wind syndrome in ischemic stroke patients.

A study of prostate delineation referenced against a gold standard created from the visible human data

International Nuclear Information System (INIS)

Gao Zhanrong; Wilkins, David; Eapen, Libni; Morash, Christopher; Wassef, Youssef; Gerig, Lee

2007-01-01

Purpose: To measure inter- and intra-observer variation and systematic error in CT based prostate delineation, where individual delineations are referenced against a gold standard produced from photographic anatomical images from the Visible Human Project (VHP). Materials and methods: The CT and anatomical images of the VHP male form the basic data set for this study. The gold standard was established based on 1 mm thick anatomical photographic images. These were registered against the 3 mm thick CT images that were used for target delineation. A total of 120 organ delineations were performed by six radiation oncologists. Results: The physician delineated prostate volume was on average 30% larger than the 'true' prostate volume, but on average included only 84% of the gold standard volume. Our study found a systematic delineation error such that posterior portions of the prostate were always missed while anteriorly some normal tissue was always defined as target. Conclusions: Our data suggest that radiation oncologists are more concerned with the unintentional inclusion of rectal tissue than they are in missing prostate volume. In contrast, they are likely to overextend the anterior boundary of the prostate to encompass normal tissue such as the bladder

No-gold-standard evaluation of image-acquisition methods using patient data.

Science.gov (United States)

Jha, Abhinav K; Frey, Eric

2017-02-11

Several new and improved modalities, scanners, and protocols, together referred to as image-acquisition methods (IAMs), are being developed to provide reliable quantitative imaging. Objective evaluation of these IAMs on the clinically relevant quantitative tasks is highly desirable. Such evaluation is most reliable and clinically decisive when performed with patient data, but that requires the availability of a gold standard, which is often rare. While no-gold-standard (NGS) techniques have been developed to clinically evaluate quantitative imaging methods, these techniques require that each of the patients be scanned using all the IAMs, which is expensive, time consuming, and could lead to increased radiation dose. A more clinically practical scenario is where different set of patients are scanned using different IAMs. We have developed an NGS technique that uses patient data where different patient sets are imaged using different IAMs to compare the different IAMs. The technique posits a linear relationship, characterized by a slope, bias, and noise standard-deviation term, between the true and measured quantitative values. Under the assumption that the true quantitative values have been sampled from a unimodal distribution, a maximum-likelihood procedure was developed that estimates these linear relationship parameters for the different IAMs. Figures of merit can be estimated using these linear relationship parameters to evaluate the IAMs on the basis of accuracy, precision, and overall reliability. The proposed technique has several potential applications such as in protocol optimization, quantifying difference in system performance, and system harmonization using patient data.

Voluntary pulmonary function screening with GOLD standard: an effective and simple approach to detect lung obstruction.

Science.gov (United States)

Wang, Shengyu; Gong, Wei; Tian, Yao; Yang, Min

2015-11-01

The prevalence of lung obstruction is probably underestimated. Early detection and screening may alter the course and prognosis associated with lung disease. We investigated the effectiveness of voluntary lung function screening program and the agreement between the Global Initiative for Chronic Obstructive Lung Disease (GOLD) and the lower limit of normal (LLN) standard for public screening in Xi'an China. Pulmonary function testing was conducted on volunteers recruited from eight community centers in Xi'an, China between July and August 2012. Participants underwent three forced vital capacity (FVC) maneuvers. The maneuver with the best FEV1 was retained. Participants filled out a medical history survey before undergoing pulmonary function testing. Patients that self-reported lung disease on the health survey were excluded from the analysis. A total of 803 volunteers participated in this study. And 722 participants (93.8%) did not self-report chronic lung disease and were analyzed. Of these participants, 143 subjects (19.8%) were diagnosed by GOLD standard and 134 subjects (18.6%) had obstruction with LLN definition. GOLD definition can identify more asymptomatic subjects (19.1%) with respect to LLN. GOLD definition can detect more lung obstruction in elder subjects compared with young people, the difference is significant (P=0.0007). The overall agreement between the 2 methods was good: the kappa estimate was 0.822. The agreement in subjects aged 40-49, 50-59 and 60-69 years was good: the kappa estimate was 0.82, 0.936 and 0.907 respectively and the agreement in subjects aged 18-29 was inferior: the kappa estimate was only 0.555. Voluntary lung function screening program with GOLD standard may be a simple and effective approach to ensuring high yield detection of lung obstruction in subjects aged 40-69.

Median sternotomy - gold standard incision for cardiac surgeons

Directory of Open Access Journals (Sweden)

Radu Matache

2016-05-01

Full Text Available Sternotomy is the gold standard incision for cardiac surgeons but it is also used in thoracic surgery especially for mediastinal, tracheal and main stem bronchus surgery. The surgical technique is well established and identification of the correct anatomic landmarks, midline tissue preparation, osteotomy and bleeding control are important steps of the procedure. Correct sternal closure is vital for avoiding short- and long-term morbidity and mortality. The two sternal halves have to be well approximated to facilitate healing of the bone and to avoid instability, which is a risk factor for wound infection. New suture materials and techniques would be expected to be developed to further improve the patients evolution, in respect to both immediate postoperative period and long-term morbidity and mortality

Endoscopic ultrasound, endoscopic sonoelastography, and strain ratio evaluation of lymph nodes with histology as gold standard

DEFF Research Database (Denmark)

Larsen, Michael Hareskov; Fristrup, Claus Wilki; Hansen, Tine Plato

2012-01-01

. Endoscopic sonoelastography (ESE) assesses the elasticity of lymph nodes and has been used to differentiate lymph nodes with promising results. The aim of this study was to evaluate the use of EUS, EUS - FNA, ESE, and ESE-strain ratio using histology as the gold standard. PATIENTS AND METHODS: Patients......, EUS - FNA and EUS - FNM were performed. The marked lymph node was isolated during surgery for histological examination. RESULTS: The marked lymph node was isolated for separate histological examination in 56 patients, of whom 22 (39 %) had malignant lymph nodes and 34 (61 %) had benign lymph nodes...... - FNM technique enabled the identification of a specific lymph node and thereby the use of histology as gold standard. ESE and ESE-strain ratio were no better than standard EUS in differentiating between malignant and benign lymph nodes in patients with resectable upper gastrointestinal cancer....

Evaluation of diagnostic tests when there is no gold standard. A review of methods

NARCIS (Netherlands)

Rutjes, A. W. S.; Reitsma, J. B.; Coomarasamy, A.; Khan, K. S.; Bossuyt, P. M. M.

2007-01-01

OBJECTIVE: To generate a classification of methods to evaluate medical tests when there is no gold standard. METHODS: Multiple search strategies were employed to obtain an overview of the different methods described in the literature, including searches of electronic databases, contacting experts

Gold-Mining

DEFF Research Database (Denmark)

Raaballe, J.; Grundy, B.D.

2002-01-01

  Based on standard option pricing arguments and assumptions (including no convenience yield and sustainable property rights), we will not observe operating gold mines. We find that asymmetric information on the reserves in the gold mine is a necessary and sufficient condition for the existence...... 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...

Underestimation of Self-Reported Smoking Prevalence in Korean Adolescents: Evidence from Gold Standard by Combined Method.

Science.gov (United States)

Hwang, Jun Hyun; Kim, Jong Yeon; Lee, Do Hoon; Jung, Hye Gyoun; Park, Soon-Woo

2018-04-05

The objective of this study was to evaluate the validity of self-reported smoking prevalence in Korean adolescents by using an improved gold standard by a combined method. Using a stratified sampling method, we selected 13 schools from among 397 high schools that participated in the 2015 Korean Youth Health Risk Behavior Web-Based Survey (KYRBS). A second survey (repeated self-reporting questionnaire and urinary cotinine test) was conducted on 1058 students who completed the KYRBS. The gold standard of current smoker was defined as those either self-reporting as a smoker in the second survey or having a urinary cotinine concentration ≥50 ng/mL. The current smoking prevalence in the first survey (KYRBS) was 7.9% (boys 16.5% and girls 1.8%), which was lower than the results based on gold standard (11.3% total, boys 21.9% and girls 3.7%). The sensitivity and specificity of self-reported smoking status was 62.5% and 99.0%, respectively. In particular, the sensitivity of girls (43.5%) was lower than that of boys (67.0%). The self-reported smoking prevalence in Korean adolescents was underestimated, particularly among girls. Careful attention should be paid to interpreting adolescents' smoking prevalence, and supplementary surveys or periodic validity tests need to be considered in Asian countries.

Fungus-mediated synthesis of gold nanoparticles and standardization of parameters for its biosynthesis.

Science.gov (United States)

Tidke, Pritish R; Gupta, Indarchand; Gade, Aniket K; Rai, Mahendra

2014-12-01

We report the extracellular biosynthesis of gold nanoparticles (AuNPs) using a fungus Fusarium acuminatum. Mycosynthesis of Au-NPs was carried out by challenging the fungal cells filtrate with HAuCl 4 solution (1 mM), as nanoparticles synthesizing enzyme secrete extracellularly by the fungi. The AuNPs were characterized with the help of UV-Visible spectrophotometer, Fourier Transform Infrared spectroscopy, Zeta Potential, X-ray diffraction (XRD) and Transmission electron microscopy (TEM). We observed absorbance peak in between 520 nm-550 nm corresponding to the surface plasmon absorbance of the gold nanoparticles. The nanoparticles synthesized in the present investigation were found to be capped by proteins. XRD results showed that the distinctive formation of crystalline gold nanoparticles in the solution. The spherical and polydispersed AuNPs in the range 8 to 28 nm with average size of 17 nm were observed by TEM analysis. We also standardized the parameters like the effect of pH, temperature and salt concentration on the biosynthesis of gold nanoparticles. It was found that acidic pH, 1 mM salt concentration and 37 (°)C temperature were found to be optimum for the synthesis of Au-NPs. Therefore, the present study introduces the easy, better and cheaper method for biosynthesis of AuNPs.

Assessing operating characteristics of CAD algorithms in the absence of a gold standard

International Nuclear Information System (INIS)

Roy Choudhury, Kingshuk; Paik, David S.; Yi, Chin A.; Napel, Sandy; Roos, Justus; Rubin, Geoffrey D.

2010-01-01

Purpose: The authors examine potential bias when using a reference reader panel as ''gold standard'' for estimating operating characteristics of CAD algorithms for detecting lesions. As an alternative, the authors propose latent class analysis (LCA), which does not require an external gold standard to evaluate diagnostic accuracy. Methods: A binomial model for multiple reader detections using different diagnostic protocols was constructed, assuming conditional independence of readings given true lesion status. Operating characteristics of all protocols were estimated by maximum likelihood LCA. Reader panel and LCA based estimates were compared using data simulated from the binomial model for a range of operating characteristics. LCA was applied to 36 thin section thoracic computed tomography data sets from the Lung Image Database Consortium (LIDC): Free search markings of four radiologists were compared to markings from four different CAD assisted radiologists. For real data, bootstrap-based resampling methods, which accommodate dependence in reader detections, are proposed to test of hypotheses of differences between detection protocols. Results: In simulation studies, reader panel based sensitivity estimates had an average relative bias (ARB) of -23% to -27%, significantly higher (p-value <0.0001) than LCA (ARB -2% to -6%). Specificity was well estimated by both reader panel (ARB -0.6% to -0.5%) and LCA (ARB 1.4%-0.5%). Among 1145 lesion candidates LIDC considered, LCA estimated sensitivity of reference readers (55%) was significantly lower (p-value 0.006) than CAD assisted readers' (68%). Average false positives per patient for reference readers (0.95) was not significantly lower (p-value 0.28) than CAD assisted readers' (1.27). Conclusions: Whereas a gold standard based on a consensus of readers may substantially bias sensitivity estimates, LCA may be a significantly more accurate and consistent means for evaluating diagnostic accuracy.

Gold standards and expert panels: a pulmonary nodule case study with challenges and solutions

Science.gov (United States)

Miller, Dave P.; O'Shaughnessy, Kathryn F.; Wood, Susan A.; Castellino, Ronald A.

2004-05-01

Comparative evaluations of reader performance using different modalities, e.g. CT with computer-aided detection (CAD) vs. CT without CAD, generally require a "truth" definition based on a gold standard. There are many situations in which a true invariant gold standard is impractical or impossible to obtain. For instance, small pulmonary nodules are generally not assessed by biopsy or resection. In such cases, it is common to use a unanimous consensus or majority agreement from an expert panel as a reference standard for actionability in lieu of the unknown gold standard for disease. Nonetheless, there are three major concerns about expert panel reference standards: (1) actionability is not synonymous with disease (2) it may be possible to obtain different conclusions about which modality is better using different rules (e.g. majority vs. unanimous consensus), and (3) the variability associated with the panelists is not formally captured in the p-values or confidence intervals that are generally produced for estimating the extent to which one modality is superior to the other. A multi-reader-multi-case (MRMC) receiver operating characteristic (ROC) study was performed using 90 cases, 15 readers, and a reference truth based on 3 experienced panelists. The primary analyses were conducted using a reference truth of unanimous consensus regarding actionability (3 out of 3 panelists). To assess the three concerns noted above: (1) additional data from the original radiology reports were compared to the panel (2) the complete analysis was repeated using different definitions of truth, and (3) bootstrap analyses were conducted in which new truth panels were constructed by picking 1, 2, or 3 panelists at random. The definition of the reference truth affected the results for each modality (CT with CAD and CT without CAD) considered by itself, but the effects were similar, so the primary analysis comparing the modalities was robust to the choice of the reference truth.

Paleozoic–early Mesozoic gold deposits of the Xinjiang Autonomous Region, northwestern China

Science.gov (United States)

Rui, Zongyao; Goldfarb, Richard J.; Qiu, Yumin; Zhou, T.; Chen, R.; Pirajno, Franco; Yun, Grace

2002-01-01

The late Paleozoic–early Mesozoic tectonic evolution of Xinjiang Autonomous Region, northwestern China provided a favorable geological setting for the formation of lode gold deposits along the sutures between a number of the major Eastern Asia cratonic blocks. These sutures are now represented by the Altay Shan, Tian Shan, and Kunlun Shan ranges, with the former two separated by the Junggar basin and the latter two by the immense Tarim basin. In northernmost Xinjiang, final growth of the Altaid orogen, southward from the Angara craton, is now recorded in the remote mid- to late Paleozoic Altay Shan. Accreted Early to Middle Devonian oceanic rock sequences contain typically small, precious-metal bearing Fe–Cu–Zn VMS deposits (e.g. Ashele). Orogenic gold deposits are widespread along the major Irtysh (e.g. Duyolanasayi, Saidi, Taerde, Kabenbulake, Akexike, Shaerbulake) and Tuergen–Hongshanzui (e.g. Hongshanzui) fault systems, as well as in structurally displaced terrane slivers of the western Junggar (e.g. Hatu) and eastern Junggar areas. Geological and geochronological constraints indicate a generally Late Carboniferous to Early Permian episode of gold deposition, which was coeval with the final stages of Altaid magmatism and large-scale, right-lateral translation along older terrane-bounding faults. The Tian Shan, an exceptionally gold-rich mountain range to the west in the Central Asian republics, is only beginning to be recognized for its gold potential in Xinjiang. In this easternmost part to the range, northerly- and southerly-directed subduction/accretion of early to mid-Paleozoic and mid- to late Paleozoic oceanic terranes, respectively, to the Precambrian Yili block (central Tian Shan) was associated with 400 to 250 Ma arc magmatism and Carboniferous through Early Permian gold-forming hydrothermal events. The more significant resulting deposits in the terranes of the southern Tian Shan include the Sawayaerdun orogenic deposit along the Kyrgyzstan

Gold deposits in the Xiaoqinling-Xiong'ershan region, Qinling mountains, central China

Science.gov (United States)

Mao, J.; Goldfarb, R.J.; Zhang, Z.; Xu, W.; Qiu, Yumin; Deng, J.

2002-01-01

The gold-rich Xiaoqinling-Xiong'ershan region in eastern Shaanxi and western Henan provinces, central China, lies about 30-50 km inland of the southern margin of the North China craton. More than 100 gold deposits and occurrences are concentrated in the Xiaoqinling (west), Xiaoshan (middle), and Xiong'ershan (east) areas. Late Archean gneiss of the Taihua Group, and Middle Proterozoic metavolcanic rocks of the Xiong'er Group are the main host rocks for the deposits. Mesozoic granitoids (ca. 178-104 Ma) are present in most gold districts, but deposits are typically hosted in the Precambrian basement rocks hundreds of meters to as far as 10 km from the intrusions and related hornfels zones. Deposits in the Xiaoqinling and Xiaoshan areas are best classified as orogenic gold deposits, with ores occurring in a number of distinct belts both in quartz veins and disseminated in altered metamorphic rocks. Alteration assemblages are dominated by quartz, sericite, pyrite, and carbonate minerals. The ore-forming fluids were low salinity, CO2-rich, and characterized by isotopically heavy ??18O. Four deposits (Dongchuang, Wenyu, Yangzhaiyu, and Dahu) in the Xiaoqinling area each contain resources of about 1 Moz Au. Some of the gold deposits in the Xiong'ershan area represent more shallowly emplaced tellurium-enriched orogenic systems, which include resources of approximately 1-1.5 Moz Au at Shanggong and Beiling (or Tantou). Others are epithermal deposits (e.g., Qiyugou and Dianfang) that are hosted in volcanic breccia pipes. Isotopic dates for all gold deposits, although often contradictory, generally cluster between 172-99 Ma and are coeval with emplacement of the post-kinematic granitoids. The gold deposits formed during a period of relaxation of far-field compressional stresses, clearly subsequent to the extensive Paleozoic-early Mesozoic accretion of are terranes and the Yangtze craton onto the southern margin of the North China craton. Hydrothermal and magmatic events

From plastic to gold: a unified classification scheme for reference standards in medical image processing

Science.gov (United States)

Lehmann, Thomas M.

2002-05-01

Reliable evaluation of medical image processing is of major importance for routine applications. Nonetheless, evaluation is often omitted or methodically defective when novel approaches or algorithms are introduced. Adopted from medical diagnosis, we define the following criteria to classify reference standards: 1. Reliance, if the generation or capturing of test images for evaluation follows an exactly determined and reproducible protocol. 2. Equivalence, if the image material or relationships considered within an algorithmic reference standard equal real-life data with respect to structure, noise, or other parameters of importance. 3. Independence, if any reference standard relies on a different procedure than that to be evaluated, or on other images or image modalities than that used routinely. This criterion bans the simultaneous use of one image for both, training and test phase. 4. Relevance, if the algorithm to be evaluated is self-reproducible. If random parameters or optimization strategies are applied, reliability of the algorithm must be shown before the reference standard is applied for evaluation. 5. Significance, if the number of reference standard images that are used for evaluation is sufficient large to enable statistically founded analysis. We demand that a true gold standard must satisfy the Criteria 1 to 3. Any standard only satisfying two criteria, i.e., Criterion 1 and Criterion 2 or Criterion 1 and Criterion 3, is referred to as silver standard. Other standards are termed to be from plastic. Before exhaustive evaluation based on gold or silver standards is performed, its relevance must be shown (Criterion 4) and sufficient tests must be carried out to found statistical analysis (Criterion 5). In this paper, examples are given for each class of reference standards.

A Bayesian method for comparing and combining binary classifiers in the absence of a gold standard

Directory of Open Access Journals (Sweden)

Keith Jonathan M

2012-07-01

Full Text Available Abstract Background Many problems in bioinformatics involve classification based on features such as sequence, structure or morphology. Given multiple classifiers, two crucial questions arise: how does their performance compare, and how can they best be combined to produce a better classifier? A classifier can be evaluated in terms of sensitivity and specificity using benchmark, or gold standard, data, that is, data for which the true classification is known. However, a gold standard is not always available. Here we demonstrate that a Bayesian model for comparing medical diagnostics without a gold standard can be successfully applied in the bioinformatics domain, to genomic scale data sets. We present a new implementation, which unlike previous implementations is applicable to any number of classifiers. We apply this model, for the first time, to the problem of finding the globally optimal logical combination of classifiers. Results We compared three classifiers of protein subcellular localisation, and evaluated our estimates of sensitivity and specificity against estimates obtained using a gold standard. The method overestimated sensitivity and specificity with only a small discrepancy, and correctly ranked the classifiers. Diagnostic tests for swine flu were then compared on a small data set. Lastly, classifiers for a genome-wide association study of macular degeneration with 541094 SNPs were analysed. In all cases, run times were feasible, and results precise. The optimal logical combination of classifiers was also determined for all three data sets. Code and data are available from http://bioinformatics.monash.edu.au/downloads/. Conclusions The examples demonstrate the methods are suitable for both small and large data sets, applicable to the wide range of bioinformatics classification problems, and robust to dependence between classifiers. In all three test cases, the globally optimal logical combination of the classifiers was found to be

Neutron activation analysis of geological samples for gold and accessory elements power reactor

International Nuclear Information System (INIS)

Burmistrenko, Yu.N.; Medvedev, A.A.; Kovalenko, V.V.; Markov, A.V.

1986-01-01

Possibility of using a power reactor for neutron activation analysis to detect gold and accompanying elements in geological samples of a region was investigated. Specimens (gold-containing samples and standards) were irradiated in a spare channel for ionization chambers located outside the core in graphite reflector. Spectrometry was conducted with the help of a semiconducting detector with LP 4900 multichannel analizer. Sensitivity threshold for gold was (1-3)10 -6 % - (1-2)10 -5 %. It is shown that this method can be used not only for gold detection but for high-sensitive multielement analysis of geological samples

Environmental stewardship for gold mining in tropical regions

Directory of Open Access Journals (Sweden)

A Isahak

2013-10-01

Full Text Available Mining has gained strong popularity in recent years due to the increase in global demand for metals and other industrial raw material derived from the ground. However, information and good governance regarding activities related to mining is still very much lacking especially in underdeveloped and developing countries in the tropics. In Malaysia, the importance of environmental stewardship in mining is a new phenomenon. The new National Mineral Policy 2 calls for compliance with existing standards and guidelines, stresses on progressive and post mining rehabilitation as well as promotes the gathering and dissemination of information, best mining practices, public disclosure and corporate social responsibility. Our preliminary studies however have shown that its implementation may have been hampered by inadequate legal and administrative structures, lack of freedom of information, physical inaccessibility, lack of information and public participation. In this presentation, the above issues and measures to reduce the impact of mining, particularly that of gold on the environment with a special focus on Malaysia is discussed. These measures include alternative gold extraction methods, appropriate tailing dam construction and management, health risk assessment and risk management, compliance with the Cyanide Code and liberalization of access to information, facilitation of access to justice, the strengthening of legal and administrative structures as well as corporate accountability to the public as part of corporate social responsibility.

Still no single gold standard for using cementless femoral stems routinely in total hip arthroplasty

Directory of Open Access Journals (Sweden)

Joseph T. Moskal, MD

2016-12-01

Conclusions: Using evidence-based data should be better guidance in selecting the most reliable implants for THA. Although cementless femoral fixation for THA has evolved to the “new standard,” it has not been proven to be the “gold standard” for all patients.

Regional radiation standards for population of Chelyabinsk region

International Nuclear Information System (INIS)

Kravtsova, Eh.M.; Zajtseva, Yh.A.; Panteleev, V.V.; Gavrilov, A.P.; Kolotygina, N.V.; Pudovkina, L.V.; Kravtsova, O.S.

1996-01-01

Regional radiation regulations for population exposures in Chelyabinsk region are developed which are to play the role of standard limits. The priority goal of setting standard level is to consolidate the achieved radioecological balance on the contaminated territories and to establish a mechanism of control over the activities of the facility and over the use of lands in restriction zone by the population

Effectiveness of the gold standard programmes (GSP) for smoking cessation in pregnant and non-pregnant women

DEFF Research Database (Denmark)

Rasmussen, Mette; Heitmann, Berit Lilienthal; Tønnesen, Hanne

2013-01-01

Smoking is considered the most important preventable risk factor in relation to the development of complications during pregnancy and delivery. The aim of this study was to evaluate the effectiveness of an intensive 6-week gold standard programme (GSP) on pregnant women in real life....

Diagnostic accuracy of tuberculous lymphadenitis fine needle aspiration biopsy confirmed by PCR as gold standard

Science.gov (United States)

DSuryadi; Delyuzar; Soekimin

2018-03-01

Indonesia is the second country with the TB (tuberculosis) burden in the world. Improvement in controlling TB and reducing the complications can accelerate early diagnosis and correct treatment. PCR test is a gold standard. However, it is quite expensive for routine diagnosis. Therefore, an accurate and cheaper diagnostic method such as fine needle aspiration biopsy is needed. The study aimsto determine the accuracy of fine needle aspiration biopsy cytology in the diagnosis of tuberculous lymphadenitis. A cross-sectional analytic study was conducted to the samples from patients suspected with tuberculous lymphadenitis. The fine needle aspiration biopsy (FNAB)test was performed and confirmed by PCR test.There is a comparison to the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of both methods. Sensitivity (92.50%), specificity (96.49%), accuracy (94.85%), positive predictive value (94.87%) and negative predictive value (94.83%) were in FNAB test compared to gold standard. We concluded that fine needle aspiration biopsy is a recommendation for a cheaper and accurate diagnostic test for tuberculous lymphadenitis diagnosis.

Twenty years after Erich Muhe: Persisting controversies with the gold standard of laparoscopic cholecystectomy

Directory of Open Access Journals (Sweden)

Jani Kalpesh

2006-01-01

Full Text Available This review article is a tribute to the genius of Professor Erich Muhe, a man ahead of his times. We trace the development of laparoscopic cholecystectomy and detail the tribulations faced by Muhe. On the occasion of the twentieth anniversary of the first laparoscopic cholecystectomy, we take another look at some of the controversies surrounding this gold standard in the management of gallbladder disease

Twenty years after Erich Muhe: Persisting controversies with the gold standard of laparoscopic cholecystectomy.

Science.gov (United States)

Jani, Kalpesh; Rajan, P S; Sendhilkumar, K; Palanivelu, C

2006-06-01

This review article is a tribute to the genius of Professor Erich Muhe, a man ahead of his times. We trace the development of laparoscopic cholecystectomy and detail the tribulations faced by Muhe. On the occasion of the twentieth anniversary of the first laparoscopic cholecystectomy, we take another look at some of the controversies surrounding this gold standard in the management of gallbladder disease.

Twenty years after Erich Muhe: Persisting controversies with the gold standard of laparoscopic cholecystectomy

OpenAIRE

Jani, Kalpesh; Rajan, P S; Sendhilkumar, K; Palanivelu, C

2006-01-01

This review article is a tribute to the genius of Professor Erich Muhe, a man ahead of his times. We trace the development of laparoscopic cholecystectomy and detail the tribulations faced by Muhe. On the occasion of the twentieth anniversary of the first laparoscopic cholecystectomy, we take another look at some of the controversies surrounding this gold standard in the management of gallbladder disease

Practical no-gold-standard evaluation framework for quantitative imaging methods: application to lesion segmentation in positron emission tomography.

Science.gov (United States)

Jha, Abhinav K; Mena, Esther; Caffo, Brian; Ashrafinia, Saeed; Rahmim, Arman; Frey, Eric; Subramaniam, Rathan M

2017-01-01

Recently, a class of no-gold-standard (NGS) techniques have been proposed to evaluate quantitative imaging methods using patient data. These techniques provide figures of merit (FoMs) quantifying the precision of the estimated quantitative value without requiring repeated measurements and without requiring a gold standard. However, applying these techniques to patient data presents several practical difficulties including assessing the underlying assumptions, accounting for patient-sampling-related uncertainty, and assessing the reliability of the estimated FoMs. To address these issues, we propose statistical tests that provide confidence in the underlying assumptions and in the reliability of the estimated FoMs. Furthermore, the NGS technique is integrated within a bootstrap-based methodology to account for patient-sampling-related uncertainty. The developed NGS framework was applied to evaluate four methods for segmenting lesions from F-Fluoro-2-deoxyglucose positron emission tomography images of patients with head-and-neck cancer on the task of precisely measuring the metabolic tumor volume. The NGS technique consistently predicted the same segmentation method as the most precise method. The proposed framework provided confidence in these results, even when gold-standard data were not available. The bootstrap-based methodology indicated improved performance of the NGS technique with larger numbers of patient studies, as was expected, and yielded consistent results as long as data from more than 80 lesions were available for the analysis.

The Gold Standard Program for Smoking Cessation is Effective for Participants Over 60 Years of Age

DEFF Research Database (Denmark)

Flamand, Mette Kehlet; Schroeder, Torben V; Tønnesen, Hanne

2015-01-01

BACKGROUND: Tobacco smoking is more prevalent among the elderly than among the young, and the elderly also have the most frequent contact with the health care system. The aim of this study was to evaluate the effectiveness of the Gold Standard Program, which is an intensive six-week smoking...

Efficiency of a solid-phase chemiluminescence immunoassay for detection of antinuclear and cytoplasmic autoantibodies compared with gold standard immunoprecipitation.

Science.gov (United States)

Gelpí, Carmen; Pérez, Elena; Roldan, Cristina

2014-09-01

The aim of this study was to compare the degree of agreement of a novel Zenit RA chemiluminescent immunoassay (CLIA) from A. Menarini Diagnostics (Florence, Italy) and the gold standard immunoprecipitation assay to screen for the presence of specific anti-U1snRNP, anti-Sm, anti-Ro/SS-A, anti-La/SS-B, anti-Jo-1((his)tRNA-Synthetase) and anti-Scl-70(Topo I) antibodies. We studied 114 sera, 98 from patients with well-defined autoimmune connective tissue diseases and 16 from blood donor volunteers. All samples were fully characterized using the new chemiluminescent immunoassay and immunoprecipitation. In addition, all the samples were analyzed by indirect immunofluorescence (IIF) and anti-Scl-70(Topo I) antibodies were analyzed by immunoblot (IB) assay. Discrepant samples were analyzed using a commercial dot blot technique (Recomline from Mikrogen). The simple Kappa coefficient was used to measure the level of agreement between the results of Zenit RA CLIA and the gold standard. The Kappa agreement between Zenit RA CLIA and gold standard immunoprecipitation, as well as IB and IIFassays for the presence of anti-Scl-70(Topo I)(0.948) was excellent. The concordance between Zenit RA CLIA and gold standard immunoprecipitation for the presence of anti-U1snRNP (0.883), anti-Ro/SS-A (0.878), anti-Jo-1((his)tRNA-Synthetase) (0.791) and anti-Sm (0.786) was good, and excellent when the cut-off was raised to 14 U/ml (arbitrary units/ml). Between Zenit RA CLIA and gold standard immunoprecipitation for the presence of anti-La/SS-B, the Kappa agreement had a value of 0.689, but this improved to 0.775 when the cut-off was raised to14 U/ml. Precision was good based on the evaluation of replicate samples. Inter-assay coefficient variation was lower than 3.4 % (CV in %) in all the kits and <1.2 % (CV in  %) for intra-assay measurements. Our findings show that Zenit RA CLIA was specific and sensitive to detect anti-U1snRNP, anti-Sm, anti-Ro/SS-A, anti-La/SS-B, anti-Jo-1((his

Gold-standard evaluation of a folksonomy-based ontology learning model

Science.gov (United States)

Djuana, E.

2018-03-01

Folksonomy, as one result of collaborative tagging process, has been acknowledged for its potential in improving categorization and searching of web resources. However, folksonomy contains ambiguities such as synonymy and polysemy as well as different abstractions or generality problem. To maximize its potential, some methods for associating tags of folksonomy with semantics and structural relationships have been proposed such as using ontology learning method. This paper evaluates our previous work in ontology learning according to gold-standard evaluation approach in comparison to a notable state-of-the-art work and several baselines. The results show that our method is comparable to the state-of the art work which further validate our approach as has been previously validated using task-based evaluation approach.

Building gold standard corpora for medical natural language processing tasks.

Science.gov (United States)

Deleger, Louise; Li, Qi; Lingren, Todd; Kaiser, Megan; Molnar, Katalin; Stoutenborough, Laura; Kouril, Michal; Marsolo, Keith; Solti, Imre

2012-01-01

We present the construction of three annotated corpora to serve as gold standards for medical natural language processing (NLP) tasks. Clinical notes from the medical record, clinical trial announcements, and FDA drug labels are annotated. We report high inter-annotator agreements (overall F-measures between 0.8467 and 0.9176) for the annotation of Personal Health Information (PHI) elements for a de-identification task and of medications, diseases/disorders, and signs/symptoms for information extraction (IE) task. The annotated corpora of clinical trials and FDA labels will be publicly released and to facilitate translational NLP tasks that require cross-corpora interoperability (e.g. clinical trial eligibility screening) their annotation schemas are aligned with a large scale, NIH-funded clinical text annotation project.

Effectiveness of the Gold Standard Programme compared with other smoking cessation interventions in Denmark: a cohort study.

Science.gov (United States)

Rasmussen, Mette; Fernández, Esteve; Tønnesen, Hanne

2017-02-27

We compared the effectiveness of the Gold Standard Programme (a comprehensive smoking cessation intervention commonly used in Denmark) with other face-to-face smoking cessation programmes in Denmark after implementation in real life, and we identified factors associated with successful quitting. Prospective cohort study. A total of 423 smoking cessation clinics from different settings reported data from 2001 to 2013. In total, 82 515 patients were registered. Smokers ≥15 years old and attending a programme with planned follow-up were included. Smokers who did not want further contact, who intentionally were not followed up or who lacked information about the intervention they received were excluded. A total of 46 287 smokers were included. Various real-life smoking cessation interventions were identified and compared: The Gold Standard Programme, Come & Quit, crash courses, health promotion counselling (brief intervention) and other interventions. Self-reported continuous abstinence for 6 months. Overall, 33% (11 184) were continuously abstinent after 6 months; this value was 24% when non-respondents were considered smokers. The follow-up rate was 74%. Women were less likely to remain abstinent, OR 0.83 (CI 0.79 to 0.87). Short interventions were more effective among men. After adjusting for confounders, the Gold Standard Programme was the only intervention with significant results across sex, increasing the odds of abstinence by 69% for men and 31% for women. In particular, compliance, and to a lesser degree, mild smoking, older age and not being disadvantaged were associated with positive outcomes for both sexes. Compliance increased the odds of abstinence more than 3.5-fold. Over time, Danish smoking cessation interventions have been effective in real life. Compliance is the main predictor of successful quitting. Interestingly, short programmes seem to have relatively strong effects among men, but the absolute numbers are very small. Only the

Evaluating the Gold Standard: A Review and Meta-Analysis of the Structured Interview of Reported Symptoms

Science.gov (United States)

Green, Debbie; Rosenfeld, Barry

2011-01-01

The Structured Interview of Reported Symptoms (SIRS; Rogers, Bagby, & Dickens, 1992) is often touted as the gold standard of measures of feigning. This label likely arises in part out of the impressive accuracy rates reported in the extensive validation research that preceded its publication. However, since its publication, researchers not only…

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.

Biomonitoring of trace-element air pollution in a gold mining area in Ghana using the generalized k0-standardization NAA method

International Nuclear Information System (INIS)

Nyarko, B.J.B.; Kyere, A.W.K.; Serfor-Armah, Y.; Akaho, E.H.K.

2003-01-01

Full text: Mining activities contribute immensely to trace element atmospheric pollution. In Ghana, air pollution due to gold mining is the least investigated. In order to obtain preliminary information on air quality in the mining areas, the generalized k o- Standardization neutron activation analysis (NAA) method for nuclides following '1/v' and non-'1/v' (n,γ) reactions was used to analyse lichen samples from Prestea, a gold mining area in Ghana. Using the computed EPI values of both the Hogdahl-convention and the modified Westcott-formalism with gold as comparator standard, the IAEA lichen 336 certified reference material (CRM) and the lichen samples were irradiated in the inner irradiation site of the Ghana Research Reactor-1 (GHARR-1) operating at a thermal neutron flux of 5.0x10 11 ns -1 cm -2 . Comparison of the results with samples obtained from a non-mining (control) area, indicates that values of some metal pollutants such as As, Cr, Sb, and V were found to be higher in the lichens from the mining area than those in the non-mining area (control area); signifying accumulation of these metal pollutant due to gold - mining activities. (author)

Moessbauer study of the chemical state of gold in gold ores

International Nuclear Information System (INIS)

Wagner, F.E.; Marion, P.H.; Regnard, J.-R.

1986-01-01

Information on the chemical state of gold in gold ores has been obtained by 197 Au Moessbauer spectroscopy in cases where the state of this element cannot be determined by such standard methods as optical or electron microscopy. Ore concentrates consisting mainly of pyrite or arsenopyrite and roasted ore and matte samples were studied. The results yielded directly the respective amounts of metallic and chemically bound gold. Unless the gold is metallic, its chemical state in the ores turns out to be different from that in the minerals studied so far as reference materials. The chemical processes taking place during various treatments of the ores, such as roasting or leaching, can also be followed by Moessbauer spectroscopy. It is hoped that Moessbauer spectroscopy will eventually facilitate the development of more efficient methods of gold extraction

Scattering resonances in bimolecular collisions between NO radicals and H2 challenge the theoretical gold standard

Science.gov (United States)

Vogels, Sjoerd N.; Karman, Tijs; Kłos, Jacek; Besemer, Matthieu; Onvlee, Jolijn; van der Avoird, Ad; Groenenboom, Gerrit C.; van de Meerakker, Sebastiaan Y. T.

2018-02-01

Over the last 25 years, the formalism known as coupled-cluster (CC) theory has emerged as the method of choice for the ab initio calculation of intermolecular interaction potentials. The implementation known as CCSD(T) is often referred to as the gold standard in quantum chemistry. It gives excellent agreement with experimental observations for a variety of energy-transfer processes in molecular collisions, and it is used to calibrate density functional theory. Here, we present measurements of low-energy collisions between NO radicals and H2 molecules with a resolution that challenges the most sophisticated quantum chemistry calculations at the CCSD(T) level. Using hitherto-unexplored anti-seeding techniques to reduce the collision energy in a crossed-beam inelastic-scattering experiment, a resonance structure near 14 cm-1 is clearly resolved in the state-to-state integral cross-section, and a unique resonance fingerprint is observed in the corresponding differential cross-section. This resonance structure discriminates between two NO-H2 potentials calculated at the CCSD(T) level and pushes the required accuracy beyond the gold standard.

The accuracy of k1-standardized INAA applied to a gold-lined well-type detector

International Nuclear Information System (INIS)

Blaauw, M.

2000-01-01

The k 1 -method for standardization in INAA specifically tackles the problem of the interpretation of gamma-ray spectra as obtained with highly efficient detectors, as opposed to the k 0 -method. Results obtained from three NIST reference materials, measured after neutron activation with a gold-lined well-type detector, are presented. It is concluded that the accuracy of the method is better than 1%. (author)

The euro and the recent European crisis vis-à-vis the gold standard and the great depression: institutionalities, specificities and interfaces

Directory of Open Access Journals (Sweden)

GIULIANO CONTENTO DE OLIVEIRA

Full Text Available ABSTRACT The paper aims to establish interfaces between the Great Depression of the 1930s under the Gold Standard and the recent European Crisis under the Euro. It is argued that, despite their specificities, both crises revealed the potentially harmful effects, in economic and social terms, of institutional arrangements that considerably reduce the autonomy of monetary, fiscal and exchange rate policies of participating countries, without being accompanied by increased cooperation between them, which should be led by a global (in the case of the Great Depression or regional (in the case of the European Crisis hegemonic power, which is not only capable of, but is also willing to act as a buyer and lender of last resort, especially in circumstances characterized by increased uncertainty, the deterioration of the general state of expectations and increased liquidity preference. In fact, central European countries in the past and peripheral European countries nowadays were effectively pushed toward deflationary adjustments in which a reduction of prices and wages was accompanied by a reduction of output and employment levels. Thus, in the absence of the possibility of restoring the autonomy of economic policy, the overcome of the crisis necessarily requires, both before - under the Gold Standard - and nowadays - under the Euro -, joint actions aimed to assure that the responsibility for the adjustment will be equally distributed among all the economies, in order to avoid that some of them benefit at the expense of the others in this process.

Nondestructive analysis of the gold quarter liras

International Nuclear Information System (INIS)

Cakir, C.; Guerol, A.; Demir, L.; Sahin, Y.

2009-01-01

In this study, we have prepared seven Au-Cu standards in the concentration range of 18-24 (as carat) for nondestructive control of gold quarter liras. Some calibration curves for quantitative analysis of Au in the gold quarter liras that commercially present in Turkey have been plotted using these standard samples. The characteristic X-rays of Au and Cu emitted from these standard samples and the test sample with known composition are recorded by using a Ge(Li) detector. These calibration curves provide a nondestructive analysis of gold quarter liras with the uncertainties about 1.18%. (author)

Electrodeposition of gold nanoparticles on mesoporous TiO{sub 2} photoelectrode to enhance visible region photocurrent

Energy Technology Data Exchange (ETDEWEB)

Supriyono,; Krisnandi, Yuni Krisyuningsih; Gunlazuardi, Jarnuzi, E-mail: jarnuzi@ui.ac.id [Department of Chemistry, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia)

2016-04-19

Electrodeposition of gold nanoparticles (Au NPs) on the mesoporous TiO{sub 2} photoelectrode to enchance visible region photocurrent have been investigated. Mesoporous TiO{sub 2} was prepared by a sol gel method and immobilized to the fluorine doped tin oxide (FTO) substrate by dip coating technique. Gold nanoparticles were electrodeposited on the TiO{sub 2} surface and the result FTO/TiO{sub 2}/Au was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), UV-Vis diffuse reflectance spectroscopy (DRS), and X-ray diffraction (XRD). The generated photocurrent was evaluated with an electrochemical workstation (e-DAQ/e-recorder 401) using 60 W wolfram lamp as visible light source. The photoelectrochemical evaluation indicated that the presence of gold nanoparticles on TiO{sub 2} photoelectrode shall enhance the photocurrent up to 50%.

Role of hydrogen ions in standard and activation heap leaching of gold

Science.gov (United States)

Rubtsov, YuI

2017-02-01

The role of hydrogen ions in activation heap leaching of gold from rebellious ore has been studied, which has allowed enhancing gold recovery. The author puts forward a gold leaching circuit with the use of activated oxygen-saturated solutions acidified to pH = 6-9.

Distribution and mobility of mercury in soils of a gold mining region, Cuyuni river basin, Venezuela.

Science.gov (United States)

Santos-Francés, F; García-Sánchez, A; Alonso-Rojo, P; Contreras, F; Adams, M

2011-04-01

An extensive and remote gold mining region located in the East of Venezuela has been studied with the aim of assessing the distribution and mobility of mercury in soil and the level of Hg pollution at artisanal gold mining sites. To do so, soils and pond sediments were sampled at sites not subject to anthropological influence, as well as in areas affected by gold mining activities. Total Hg in regionally distributed soils ranged between 0.02 mg kg(-1) and 0.40 mg kg(-1), with a median value of 0.11 mg kg(-1), which is slightly higher than soil Hg worldwide, possibly indicating long-term atmospheric input or more recent local atmospheric input, in addition to minor lithogenic sources. A reference Hg concentration of 0.33 mg kg(-1) is proposed for the detection of mining affected soils in this region. Critical total Hg concentrations were found in the surrounding soils of pollutant sources, such as milling-amalgamation sites, where soil Hg contents ranged from 0.16 mg kg(-1) to 542 mg kg(-1) with an average of 26.89 mg kg(-1), which also showed high levels of elemental Hg, but quite low soluble+exchangeable Hg fraction (0.02-4.90 mg kg(-1)), suggesting low Hg soil mobility and bioavailability, as confirmed by soil column leaching tests. The vertical distribution of Hg through the soil profiles, as well as variations in soil Hg contents with distance from the pollution source, and Hg in pond mining sediments were also analysed. Copyright © 2010 Elsevier Ltd. All rights reserved.

Grading School Choice: Evaluating School Choice Programs by the Friedman Gold Standard. School Choice Issues in Depth

Science.gov (United States)

Enlow, Robert C.

2008-01-01

In 2004, The Friedman Foundation for Educational Choice published a report titled "Grading Vouchers: Ranking America's School Choice Programs." Its purpose was to measure every existing school choice program against the gold standard set by Milton and Rose Friedman: that the most effective way to improve K-12 education and thus ensure a stable…

GOFC-GOLD/LCLUC/START Regional Networking: building capacity for science and decision-making.

Science.gov (United States)

Justice, C. O.; Vadrevu, K.; Gutman, G.

2016-12-01

Over the past 20 years, the international GOFC-GOLD Program and START, with core funding from the NASA LCLUC program and ESA have been developing regional networks of scientists and data users for scientific capacity building and sharing experience in the use and application of Earth Observation data. Regional networks connect scientists from countries with similar environmental and social issues and often with shared water and airsheds. Through periodic regional workshops, regional and national projects are showcased and national priorities and policy drivers are articulated. The workshops encourage both north-south and south-south exchange and collaboration. The workshops are multi-sponsored and each include a training component, targeting early career scientists and data users from the region. The workshops provide an opportunity for regional scientists to publish in peer-reviewed special editions focused on regional issues. Currently, the NASA LCLUC program funded "South and Southeast Asia Regional Initiative (SARI)" team is working closely with the USAID/NASA SERVIR program to implement some capacity building and training activities jointly in south/southeast Asian countries to achieve maximum benefit.

A Gold Standards Approach to Training Instructors to Evaluate Crew Performance

Science.gov (United States)

Baker, David P.; Dismukes, R. Key

2003-01-01

The Advanced Qualification Program requires that airlines evaluate crew performance in Line Oriented Simulation. For this evaluation to be meaningful, instructors must observe relevant crew behaviors and evaluate those behaviors consistently and accurately against standards established by the airline. The airline industry has largely settled on an approach in which instructors evaluate crew performance on a series of event sets, using standardized grade sheets on which behaviors specific to event set are listed. Typically, new instructors are given a class in which they learn to use the grade sheets and practice evaluating crew performance observed on videotapes. These classes emphasize reliability, providing detailed instruction and practice in scoring so that all instructors within a given class will give similar scores to similar performance. This approach has value but also has important limitations; (1) ratings within one class of new instructors may differ from those of other classes; (2) ratings may not be driven primarily by the specific behaviors on which the company wanted the crews to be scored; and (3) ratings may not be calibrated to company standards for level of performance skill required. In this paper we provide a method to extend the existing method of training instructors to address these three limitations. We call this method the "gold standards" approach because it uses ratings from the company's most experienced instructors as the basis for training rater accuracy. This approach ties the training to the specific behaviors on which the experienced instructors based their ratings.

“Gold Standards,” Plurality and Monocultures: The Need for Diversity in Psychotherapy

Directory of Open Access Journals (Sweden)

Falk Leichsenring

2018-04-01

Full Text Available For psychotherapy of mental disorders, presently several approaches are available, such as interpersonal, humanistic, systemic, psychodynamic or cognitive behavior therapy (CBT. Pointing to the available evidence, proponents of CBT claim that CBT is the gold standard. Some authors even argue for an integrated CBT-based form of psychotherapy as the only form of psychotherapy. CBT undoubtedly has its strengths and CBT researchers have to be credited for developing and testing treatments for many mental disorders. A critical review, however, shows that the available evidence for the theoretical foundations of CBT, assumed mechanisms of change, quality of studies, and efficacy is not as robust as some researchers claim. Most important, there is no consistent evidence that CBT is more efficacious than other evidence-based approaches. These findings do not justify regarding CBT as the gold standard psychotherapy. They even provide less justification for the idea that the future of psychotherapy lies in one integrated CBT-based form of psychotherapy as the only type of psychotherapy. For the different psychotherapeutic approaches a growing body of evidence is available. These approaches have their strengths because of differences in their respective focus on interpersonal relationships, affects, cognitions, systemic perspectives, experiential, or unconscious processes. Different approaches may be suitable to different patients and therapists. As generally assumed, progress in research results from openness to new ideas and learning from diverse perspectives. Thus, different forms of evidence-based psychotherapy are required. Plurality is the future of psychotherapy, not a uniform “one fits all” approach.

“Gold Standards,” Plurality and Monocultures: The Need for Diversity in Psychotherapy

Science.gov (United States)

Leichsenring, Falk; Abbass, Allan; Hilsenroth, Mark J.; Luyten, Patrick; Munder, Thomas; Rabung, Sven; Steinert, Christiane

2018-01-01

For psychotherapy of mental disorders, presently several approaches are available, such as interpersonal, humanistic, systemic, psychodynamic or cognitive behavior therapy (CBT). Pointing to the available evidence, proponents of CBT claim that CBT is the gold standard. Some authors even argue for an integrated CBT-based form of psychotherapy as the only form of psychotherapy. CBT undoubtedly has its strengths and CBT researchers have to be credited for developing and testing treatments for many mental disorders. A critical review, however, shows that the available evidence for the theoretical foundations of CBT, assumed mechanisms of change, quality of studies, and efficacy is not as robust as some researchers claim. Most important, there is no consistent evidence that CBT is more efficacious than other evidence-based approaches. These findings do not justify regarding CBT as the gold standard psychotherapy. They even provide less justification for the idea that the future of psychotherapy lies in one integrated CBT-based form of psychotherapy as the only type of psychotherapy. For the different psychotherapeutic approaches a growing body of evidence is available. These approaches have their strengths because of differences in their respective focus on interpersonal relationships, affects, cognitions, systemic perspectives, experiential, or unconscious processes. Different approaches may be suitable to different patients and therapists. As generally assumed, progress in research results from openness to new ideas and learning from diverse perspectives. Thus, different forms of evidence-based psychotherapy are required. Plurality is the future of psychotherapy, not a uniform “one fits all” approach. PMID:29740361

An investigation into the validity of cervical spine motion palpation using subjects with congenital block vertebrae as a 'gold standard'

Directory of Open Access Journals (Sweden)

Peterson Cynthia K

2004-06-01

Full Text Available Abstract Background Although the effectiveness of manipulative therapy for treating back and neck pain has been demonstrated, the validity of many of the procedures used to detect joint dysfunction has not been confirmed. Practitioners of manual medicine frequently employ motion palpation as a diagnostic tool, despite conflicting evidence regarding its utility and reliability. The introduction of various spinal models with artificially introduced 'fixations' as an attempt to introduce a 'gold standard' has met with frustration and frequent mechanical failure. Because direct comparison against a 'gold standard' allows the validity, specificity and sensitivity of a test to be calculated, the identification of a realistic 'gold standard' against which motion palpation can be evaluated is essential. The objective of this study was to introduce a new, realistic, 'gold standard', the congenital block vertebra (CBV to assess the validity of motion palpation in detecting a true fixation. Methods Twenty fourth year chiropractic students examined the cervical spines of three subjects with single level congenital block vertebrae, using two commonly employed motion palpation tests. The examiners, who were blinded to the presence of congenital block vertebrae, were asked to identify the most hypomobile segment(s. The congenital block segments included two subjects with fusion at the C2–3 level and one with fusion at C5-6. Exclusion criteria included subjects who were frankly symptomatic, had moderate or severe degenerative changes in their cervical spines, or displayed signs of cervical instability. Spinal levels were marked on the subject's skin overlying the facet joints from C1 to C7 bilaterally and the motion segments were then marked alphabetically with 'A' corresponding to C1-2. Kappa coefficients (K were calculated to determine the validity of motion palpation to detect the congenitally fused segments as the 'most hypomobile' segments. Sensitivity

Detection of Echinococcus multilocularis by MC-PCR: evaluation of diagnostic sensitivity and specificity without gold standard

Directory of Open Access Journals (Sweden)

Helene Wahlström

2016-03-01

Full Text Available Introduction: A semi-automated magnetic capture probe-based DNA extraction and real-time PCR method (MC-PCR, allowing for a more efficient large-scale surveillance of Echinococcus multilocularis occurrence, has been developed. The test sensitivity has previously been evaluated using the sedimentation and counting technique (SCT as a gold standard. However, as the sensitivity of the SCT is not 1, test characteristics of the MC-PCR was also evaluated using latent class analysis, a methodology not requiring a gold standard. Materials and methods: Test results, MC-PCR and SCT, from a previous evaluation of the MC-PCR using 177 foxes shot in the spring (n=108 and autumn 2012 (n=69 in high prevalence areas in Switzerland were used. Latent class analysis was used to estimate the test characteristics of the MC-PCR. Although it is not the primary aim of this study, estimates of the test characteristics of the SCT were also obtained. Results and discussion: This study showed that the sensitivity of the MC-PCR was 0.88 [95% posterior credible interval (PCI 0.80–0.93], which was not significantly different than the SCT, 0.83 (95% PCI 0.76–0.88, which is currently considered as the gold standard. The specificity of both tests was high, 0.98 (95% PCI 0.94–0.99 for the MC-PCR and 0.99 (95% PCI 0.99–1 for the SCT. In a previous study, using fox scats from a low prevalence area, the specificity of the MC-PCR was higher, 0.999% (95% PCI 0.997–1. One reason for the lower estimate of the specificity in this study could be that the MC-PCR detects DNA from infected but non-infectious rodents eaten by foxes. When using MC-PCR in low prevalence areas or areas free from the parasite, a positive result in the MC-PCR should be regarded as a true positive. Conclusion: The sensitivity of the MC-PCR (0.88 was comparable to the sensitivity of SCT (0.83.

Quantitative Rapid Assessment of Leukoaraiosis in CT : Comparison to Gold Standard MRI.

Science.gov (United States)

Hanning, Uta; Sporns, Peter Bernhard; Schmidt, Rene; Niederstadt, Thomas; Minnerup, Jens; Bier, Georg; Knecht, Stefan; Kemmling, André

2017-10-20

The severity of white matter lesions (WML) is a risk factor of hemorrhage and predictor of clinical outcome after ischemic stroke; however, in contrast to magnetic resonance imaging (MRI) reliable quantification for this surrogate marker is limited for computed tomography (CT), the leading stroke imaging technique. We aimed to present and evaluate a CT-based automated rater-independent method for quantification of microangiopathic white matter changes. Patients with suspected minor stroke (National Institutes of Health Stroke scale, NIHSS < 4) were screened for the analysis of non-contrast computerized tomography (NCCT) at admission and compared to follow-up MRI. The MRI-based WML volume and visual Fazekas scores were assessed as the gold standard reference. We employed a recently published probabilistic brain segmentation algorithm for CT images to determine the tissue-specific density of WM space. All voxel-wise densities were quantified in WM space and weighted according to partial probabilistic WM content. The resulting mean weighted density of WM space in NCCT, the surrogate of WML, was correlated with reference to MRI-based WML parameters. The process of CT-based tissue-specific segmentation was reliable in 79 cases with varying severity of microangiopathy. Voxel-wise weighted density within WM spaces showed a noticeable correlation (r = -0.65) with MRI-based WML volume. Particularly in patients with moderate or severe lesion load according to the visual Fazekas score the algorithm provided reliable prediction of MRI-based WML volume. Automated observer-independent quantification of voxel-wise WM density in CT significantly correlates with microangiopathic WM disease in gold standard MRI. This rapid surrogate of white matter lesion load in CT may support objective WML assessment and therapeutic decision-making during acute stroke triage.

Web 2.0-based crowdsourcing for high-quality gold standard development in clinical natural language processing.

Science.gov (United States)

Zhai, Haijun; Lingren, Todd; Deleger, Louise; Li, Qi; Kaiser, Megan; Stoutenborough, Laura; Solti, Imre

2013-04-02

A high-quality gold standard is vital for supervised, machine learning-based, clinical natural language processing (NLP) systems. In clinical NLP projects, expert annotators traditionally create the gold standard. However, traditional annotation is expensive and time-consuming. To reduce the cost of annotation, general NLP projects have turned to crowdsourcing based on Web 2.0 technology, which involves submitting smaller subtasks to a coordinated marketplace of workers on the Internet. Many studies have been conducted in the area of crowdsourcing, but only a few have focused on tasks in the general NLP field and only a handful in the biomedical domain, usually based upon very small pilot sample sizes. In addition, the quality of the crowdsourced biomedical NLP corpora were never exceptional when compared to traditionally-developed gold standards. The previously reported results on medical named entity annotation task showed a 0.68 F-measure based agreement between crowdsourced and traditionally-developed corpora. Building upon previous work from the general crowdsourcing research, this study investigated the usability of crowdsourcing in the clinical NLP domain with special emphasis on achieving high agreement between crowdsourced and traditionally-developed corpora. To build the gold standard for evaluating the crowdsourcing workers' performance, 1042 clinical trial announcements (CTAs) from the ClinicalTrials.gov website were randomly selected and double annotated for medication names, medication types, and linked attributes. For the experiments, we used CrowdFlower, an Amazon Mechanical Turk-based crowdsourcing platform. We calculated sensitivity, precision, and F-measure to evaluate the quality of the crowd's work and tested the statistical significance (Pcrowdsourced and traditionally-developed annotations. The agreement between the crowd's annotations and the traditionally-generated corpora was high for: (1) annotations (0.87, F-measure for medication names

A no-gold-standard technique for objective assessment of quantitative nuclear-medicine imaging methods.

Science.gov (United States)

Jha, Abhinav K; Caffo, Brian; Frey, Eric C

2016-04-07

The objective optimization and evaluation of nuclear-medicine quantitative imaging methods using patient data is highly desirable but often hindered by the lack of a gold standard. Previously, a regression-without-truth (RWT) approach has been proposed for evaluating quantitative imaging methods in the absence of a gold standard, but this approach implicitly assumes that bounds on the distribution of true values are known. Several quantitative imaging methods in nuclear-medicine imaging measure parameters where these bounds are not known, such as the activity concentration in an organ or the volume of a tumor. We extended upon the RWT approach to develop a no-gold-standard (NGS) technique for objectively evaluating such quantitative nuclear-medicine imaging methods with patient data in the absence of any ground truth. Using the parameters estimated with the NGS technique, a figure of merit, the noise-to-slope ratio (NSR), can be computed, which can rank the methods on the basis of precision. An issue with NGS evaluation techniques is the requirement of a large number of patient studies. To reduce this requirement, the proposed method explored the use of multiple quantitative measurements from the same patient, such as the activity concentration values from different organs in the same patient. The proposed technique was evaluated using rigorous numerical experiments and using data from realistic simulation studies. The numerical experiments demonstrated that the NSR was estimated accurately using the proposed NGS technique when the bounds on the distribution of true values were not precisely known, thus serving as a very reliable metric for ranking the methods on the basis of precision. In the realistic simulation study, the NGS technique was used to rank reconstruction methods for quantitative single-photon emission computed tomography (SPECT) based on their performance on the task of estimating the mean activity concentration within a known volume of interest

A no-gold-standard technique for objective assessment of quantitative nuclear-medicine imaging methods

International Nuclear Information System (INIS)

Jha, Abhinav K; Frey, Eric C; Caffo, Brian

2016-01-01

The objective optimization and evaluation of nuclear-medicine quantitative imaging methods using patient data is highly desirable but often hindered by the lack of a gold standard. Previously, a regression-without-truth (RWT) approach has been proposed for evaluating quantitative imaging methods in the absence of a gold standard, but this approach implicitly assumes that bounds on the distribution of true values are known. Several quantitative imaging methods in nuclear-medicine imaging measure parameters where these bounds are not known, such as the activity concentration in an organ or the volume of a tumor. We extended upon the RWT approach to develop a no-gold-standard (NGS) technique for objectively evaluating such quantitative nuclear-medicine imaging methods with patient data in the absence of any ground truth. Using the parameters estimated with the NGS technique, a figure of merit, the noise-to-slope ratio (NSR), can be computed, which can rank the methods on the basis of precision. An issue with NGS evaluation techniques is the requirement of a large number of patient studies. To reduce this requirement, the proposed method explored the use of multiple quantitative measurements from the same patient, such as the activity concentration values from different organs in the same patient. The proposed technique was evaluated using rigorous numerical experiments and using data from realistic simulation studies. The numerical experiments demonstrated that the NSR was estimated accurately using the proposed NGS technique when the bounds on the distribution of true values were not precisely known, thus serving as a very reliable metric for ranking the methods on the basis of precision. In the realistic simulation study, the NGS technique was used to rank reconstruction methods for quantitative single-photon emission computed tomography (SPECT) based on their performance on the task of estimating the mean activity concentration within a known volume of interest

A Preliminary Study on Detecting Fake Gold Bars Using Prompt Gamma Activation Analysis: Simulation of Neutron Transmission in Gold Bar

Energy Technology Data Exchange (ETDEWEB)

Lee, K. M.; Sun, G. M. [KAERI, Daejeon (Korea, Republic of)

2016-05-15

The purpose of this study is to develop fake gold bar detecting method by using Prompt-gamma activation analysis (PGAA) facility at the Korea Atomic Energy Research Institute (KAERI). PGAA is an established nuclear analytical technique for non-destructive determination of elemental and isotopic compositions. For a preliminary study on detecting fake gold bar, Monte Carlo simulation of neutron transmission in gold bar was conducted and the possibility for detecting fake gold bar was confirmed. Under the gold bullion standard, it guaranteed the government would redeem any amount of currency for its value in gold. After the gold bullion standard ended, gold bars have been the target for investment as ever. But it is well known that fake gold bar exist in the gold market. This cannot be identified easily without performing a testing as it has the same appearance as the pure gold bar. In order to avoid the trading of fake gold bar in the market, they should be monitored thoroughly. Although the transmissivity of cold neutrons are low comparing that of thermal neutrons, the slower neutrons are more apt to be absorbed in a target, and can increase the prompt gamma emission rate. Also the flux of both thermal and cold neutron beam is high enough to activate thick target. If the neutron beam is irradiated on the front and the reverse side of gold bar, all insides of it can be detected.

A Preliminary Study on Detecting Fake Gold Bars Using Prompt Gamma Activation Analysis: Simulation of Neutron Transmission in Gold Bar

International Nuclear Information System (INIS)

Lee, K. M.; Sun, G. M.

2016-01-01

The purpose of this study is to develop fake gold bar detecting method by using Prompt-gamma activation analysis (PGAA) facility at the Korea Atomic Energy Research Institute (KAERI). PGAA is an established nuclear analytical technique for non-destructive determination of elemental and isotopic compositions. For a preliminary study on detecting fake gold bar, Monte Carlo simulation of neutron transmission in gold bar was conducted and the possibility for detecting fake gold bar was confirmed. Under the gold bullion standard, it guaranteed the government would redeem any amount of currency for its value in gold. After the gold bullion standard ended, gold bars have been the target for investment as ever. But it is well known that fake gold bar exist in the gold market. This cannot be identified easily without performing a testing as it has the same appearance as the pure gold bar. In order to avoid the trading of fake gold bar in the market, they should be monitored thoroughly. Although the transmissivity of cold neutrons are low comparing that of thermal neutrons, the slower neutrons are more apt to be absorbed in a target, and can increase the prompt gamma emission rate. Also the flux of both thermal and cold neutron beam is high enough to activate thick target. If the neutron beam is irradiated on the front and the reverse side of gold bar, all insides of it can be detected

Extraction of gold (Au) particles from sea water by Delftia Acidovorans microbes

Science.gov (United States)

Yusoff, A. H. M.; Nading, M. E.; Salimi, M. N.

2017-10-01

Gold-mining activities have been an issue, especially when it involves in contamination of chemicals, for example arsenic and mercury. However, despite of these hazards, gold-mining activities are still being conducted. This is because the gold is worth, regardless of the problems. Gold-mining, as known needs a very large area of land, or site plant. Vast amount of labor force, mechanical force and fund are a must in order for the mining process to be continued. High demand of gold, made gold-mining industries as ones of the most profitable industries in the world. Thus, this has encouraged another alternative way to extract gold. At the mining site, researchers found that biomineralization of gold by Delftia acidovorans can be conducted. How it is done still cannot be understood. It is said that the bacteria secretes secondary metabolites, Delftibactin as a defensive mechanism against the toxicity of the soluble gold. Researchers try to find another source of elemental gold besides of the earth’s core. The options are either lava of a volcano or ocean. Here, the focus is seawater. The problem of seawater is that its composition still not yet to be proved. Dissolve gold existed as gold chloride in seawater, but in a very small amount. So, the gold separation should be focused, in order to make this process to be a successful one. Factors such as depth, climate, region, temperature need to be considered. If this difference affecting the separating process, standardized seawater composition have to be proposed.

Gold-coated copper cone detector as a new standard detector for F2 laser radiation at 157 nm

International Nuclear Information System (INIS)

Kueck, Stefan; Brandt, Friedhelm; Taddeo, Mario

2005-01-01

A new standard detector for high-accuracy measurements of F2 laser radiation at 157 nm is presented. This gold-coated copper cone detector permits the measurement of average powers up to 2 W with an uncertainty of ∼1%. To the best of our knowledge, this is the first highly accurate standard detector for F2 laser radiation for this power level. It is fully characterized according to Guide to the Expression of Uncertainty in Measurement of the International Organization for Standardization and is connected to the calibration chain for laser radiation established by the German National Metrology Institute

Real-time PCR versus viral culture on urine as a gold standard in the diagnosis of congenital cytomegalovirus infection

NARCIS (Netherlands)

de Vries, Jutte J. C.; van der Eijk, Annemiek A.; Wolthers, Katja C.; Rusman, Lisette G.; Pas, Suzan D.; Molenkamp, Richard; Claas, Eric C.; Kroes, Aloys C. M.; Vossen, Ann C. T. M.

2012-01-01

Background: Cytomegalovirus (CMV) infection is the most common cause of congenital infection. Whereas CMV PCR has replaced viral culture and antigen detection in immunocompromised patients because of higher sensitivity, viral culture of neonatal urine is still referred to as the gold standard in the

Estimation of Sensitivity and Specificity of Three Conditionally Dependent Diagnostic Tests in the Absence of a Gold Standard

NARCIS (Netherlands)

Engel, B.; Swildens, B.; Stegeman, J.A.; Buist, W.G.; Jong, de M.

2006-01-01

This article presents a model to evaluate the accuracy of diagnostic tests. Data from three tests for the detection of EF-positive Streptococcus suis serotype 2 strains in sows were analyzed. The data were collected in a field study in the absence of a gold standard, that is, the true disease status

Low-energy ED-XRF spectrometry application in gold assaying

International Nuclear Information System (INIS)

Marucco, Alessandra

2004-01-01

The performances of a low-energy dispersive XRF spectrometer in gold assaying are evaluated by a series of analysis on international standards and other certified gold alloys with. Results of standard-free analysis based on fundamental parameters method compared to results of multi-standard method, demonstrate a large gain of accuracy by drawing appropriate calibration curves with use of 1 to 16 matrix-specific standards. The accuracy of gold assaying has improved by a factor of 10, as compared to the conventional touchstone test. This rather economical technique satisfies then numerous precious alloys analyst needs, representing an excellent alternative to the traditional method for quick anti-fraud controls

SHORT- AND LONG-TERM BOND STRENGTHS OF A GOLD STANDARD

Directory of Open Access Journals (Sweden)

Safa TUNCER

2015-04-01

Full Text Available Purpose: The aim of this study was to investigate the micro tensile bond strength of a self-etch adhesive system following 1 year storage in water. Materials and Methods: 10 sound human molar teeth were used for micro tensile bond strength test. Twostep self-etch dentin adhesive (Clearfil SE Bond® was applied to the flat dentin surfaces according to the manufacturer’s instructions. Composite blocks (Z- 250; 3M ESPE of 5 mm in height have been prepared by using layering technique. Teeth were stored in water for 24 hours at 37°C and longitudinally sectioned to obtain dentin sticks of 1 mm2.Randomly selected samples from half of the teeth were immediately subjected to micro tensile test and. Remaining specimens were tested after 1 year storage in water. Bond strengths were calculated in megapascal (MPa. Results: Means and standard deviations of the Clearfil SE Bond® micro tensile bond strength values were, respectively, 37.31 ± 13.77 MPa and 24.78 ± 2.99 MPa after 24 h and 1 year of storage in water. The difference was statistically significant (p=0.031. Conclusion: Long-term storage in water decreased the micro tensile bond strength values of the twostep self-etch adhesive which has been accepted as the gold standard in bond strength tests.

Thrombelastography detects dabigatran at therapeutic concentrations in vitro to the same extent as gold-standard tests

DEFF Research Database (Denmark)

Solbeck, Sacha; Ostrowski, Sisse R; Stensballe, Jakob

2016-01-01

BACKGROUND/OBJECTIVES: Dabigatran is an oral anticoagulant approved for treatment of non-valvular atrial fibrillation, deep venous thrombosis (DVT), pulmonary embolism and prevention of DVT following orthopedic surgery. Monitoring of the dabigatran level is essential in trauma and bleeding patien...... to the current gold-standard tests Hemoclot and ECT, for assessing dabigatran. TEG R is applicable as a rapid and precise whole blood monitoring test for dabigatran treated patients in the emergency setting....

Substoichiometric neutron activation determination of gold

International Nuclear Information System (INIS)

Mitchell, J.W.; Riley, J.E. Jr.; Payne, V.

1978-01-01

A highly precise and selective method is described for the determination of traces of gold by substoichiometric extraction from hydrochloric acid with tri-n-octylphosphine sulfide in cyclohexane following thermal neutron activation. Fundamental aspects of the extraction system are discussed and results are reported for the determination of gold in an effluent from a recovery process containing a complexed species of gold and unknown amounts of cyanide, citrate, phosphate, potassium and sodium. Other constituents of the effluent stream include traces of the transition elements Co, Ni, Fe, Cu, Zn, Pb and Sn at concentrations less than 50 ppm. One hour was allowed for the Au 3+ carrier and the 198 Au complexed species in samples and standards to oxidize, exchange, and reach chemical equilibrium. Samples were then equilibrated by shaking with the organic phase for thirty min. The percentage extractions (%E) for the substoichiometric separation of gold from the effluent and from the corresponding comparison standards were monitored. The mean percentage extractions for the substoichiometric separations of carrier from the effluent, and its corresponding standard were 75.3 and 59.3, respectively. These data are estimated to be accurate within +-2.0%. (T.G.)

Mercury and arsenic in the gold mining regions of the Ankobra River basin in Ghana

Science.gov (United States)

Bannerman, W.; Potin-Gautier, M.; Amoureux, D.; Tellier, S.; Rambaud, A.; Babut, M.; Adimado, A.; Beinhoff, C.

2003-05-01

The river Ankobra flows through the principal gold mining centres in Western Ghana, draining a total area of 8272 km^2 to join the Atlantic ocean. Mercury is used by thousands of small-scale miners in the region to amalgamate gold. Ores mined in some deep shafts and surface mines are arsenopyrites and the region is marked by the presence of heaps of arsenic - rich mine tailings from both past and recent activities. This study was conducted to assess the impact of mining activities on the distribution and speciation of arsenic and mercury in the aquatic environment of the Ankobra River. In all, water (filtered and non-filtered) and bed sediments were collected from various locations within the watershed. Principal parameters investigated include total mercury, arsenic (III), arsenic (V), monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA). Seasonal and spatial variations of these parameters were investigated. Quality control systems were adopted at both the environmental and analytical stages of the study. ln general, areas close to the mining centres are the most pollilited. As (V)/As (III) ratios in water are reversed after the first 100-km of the river length with the onset of industrial influence downstream.

Imatinib mesylate--gold standards and silver linings.

Science.gov (United States)

Peggs, K

2004-09-01

Imatinib mesylate represents the first of a new generation of molecularly targeted therapies engineered to disrupt signal transduction pathways. It is a tyrosine kinase inhibitor with relatively selective activity against the Abelson (ABL) proto-oncogene, platelet-derived growth factor receptor, and c-KIT receptor. Deregulated tyrosine kinase activity has been implicated as a central pathogenic event in a number of human malignancies, most notably chronic myeloid leukemia. In this myeloproliferative disorder the t(9;22) reciprocal translocation results in the generation of a novel fusion oncoprotein, BCR-ABL, with constitutive tyrosine kinase activity. Imatinib inhibits this activity, inducing remarkable rates of hematological and cytogenetic remission in excess of those seen with alternative medical therapies. Following a large phase III study comparing its efficacy with the combination of interferon alpha and low-dose cytarabine, it has emerged as the current gold standard therapy for patients with chronic-phase disease without a potential bone marrow donor and those considered unsuitable for bone marrow transplantation. Its integration into the management of those patients who might be considered for transplantation, which has historically been considered the only potentially curative approach, remains a major challenge. The increasing recognition and subsequent molecular characterization of resistance mechanisms has reinforced the need to exercise caution against deferring a proven curative therapy in favor of a treatment approach that is still investigational, with the spectre of increased numbers of patients progressing to sudden-onset blast crisis remaining the potential dark cloud in the silver lining for imatinib.

Gold standard program for heavy smokers in a real-life setting

DEFF Research Database (Denmark)

Neumann, Tim; Rasmussen, Mette; Heitmann, Berit L

2013-01-01

Background: High-intensity smoking cessation programs generally lead to more continuous abstinence, however, lower rates of success have been reported among heavy smokers. The aim was to evaluate continuous abstinence among heavy smokers during the intensive 6-week Gold Standard Program (GSP......) and to identify modifiable factors associated with continuous abstinence. Methods: In this nationwide clinical study based on 36,550 smokers attending an intensive cessation program in Denmark. Heavy smoking was defined as ≥7 points in the Fagerström Nicotine Dependency Test, smoking ≥20 cigarettes daily or ≥20...... pack-years. Results: Overall, 28% had a Fagerström score ≥7 points, 58% smoked ≥20 cigarettes daily and 68% smoked ≥20 pack-years. Continuous abstinence was 33% in responders (6-months response rate: 78%); however, abstinence was approximately 1-6% lower in the heavy smokers than the overall population...

Progression-free survival: gaining on overall survival as a gold standard and accelerating drug development.

Science.gov (United States)

Lebwohl, David; Kay, Andrea; Berg, William; Baladi, Jean Francois; Zheng, Ji

2009-01-01

In clinical trials of oncology drugs, overall survival (OS) is a direct measure of clinical efficacy and is considered the gold standard primary efficacy end point. The purpose of this study was to discuss the difficulties in using OS as a primary efficacy end point in the setting of evolving cancer therapies. We suggest that progression-free survival is an appropriate efficacy end point in many types of cancer, specifically those for which OS is expected to be prolonged and for which subsequent treatments are expected to affect OS.

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.

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.

Study of gold-platinum and platinum-gold surface modification and its influence on hydrogen evolution and oxygen reduction

Directory of Open Access Journals (Sweden)

BRANIMIR N. GRGUR

2005-02-01

Full Text Available Surface modification of the electrodes was conducted from sulfuric acid solutions containing the corresponding metal–chloride complexes using cyclic voltammetry. Comparing the charges of the hydrogen underpotential deposition region, and the corresponding oxide reduction regions, it is concluded that a platinum overlayer on gold forms 3D islands, while gold on platinum forms 2D islands. Foreign metals present in an amount of up to one monolayer exert an influence on the change in reaction rate with respect to both hydrogen evolution (HER and oxygen reduction (ORR reactions. Aplatinum overlayer on a gold substrate increases the activity forHER and for ORR, compared with pure gold. These results can be understood in terms of a simple model, in which the change in the H and OH binding energies are directly proportional to the shift of the d-bond center of the overlayer. On the contrary, a gold layer on platinum slightly decreases the activity for both reactions compared with pure platinum.

When do latent class models overstate accuracy for diagnostic and other classifiers in the absence of a gold standard?

Science.gov (United States)

Spencer, Bruce D

2012-06-01

Latent class models are increasingly used to assess the accuracy of medical diagnostic tests and other classifications when no gold standard is available and the true state is unknown. When the latent class is treated as the true class, the latent class models provide measures of components of accuracy including specificity and sensitivity and their complements, type I and type II error rates. The error rates according to the latent class model differ from the true error rates, however, and empirical comparisons with a gold standard suggest the true error rates often are larger. We investigate conditions under which the true type I and type II error rates are larger than those provided by the latent class models. Results from Uebersax (1988, Psychological Bulletin 104, 405-416) are extended to accommodate random effects and covariates affecting the responses. The results are important for interpreting the results of latent class analyses. An error decomposition is presented that incorporates an error component from invalidity of the latent class model. © 2011, The International Biometric Society.

Diagnostic tests for Helicobacter pylori : A prospective evaluation of their accuracy, without selecting a single test as the gold standard

NARCIS (Netherlands)

Thijs, J C; van Zwet, A A; Thijs, W J; Oey, H B; Karrenbeld, A; Stellaard, F; Luijt, D S; Meyer, B C; Kleibeuker, J H

1996-01-01

OBJECTIVE: To assess the accuracy of six commonly used diagnostic tests for Helicobacter pylori in a prospective study without using any specific test as the gold standard (the patient was regarded as H. pylori-infected if two or more tests, whatever their nature, were positive). METHODS: In 105

Investigation on cold-drawn gold bonding wire with serial and reverse-direction drawing

International Nuclear Information System (INIS)

Cho, Jae-Hyung; Rollett, A.D.; Cho, J.-S.; Park, Y.-J.; Park, S.-H.; Oh, K.H.

2006-01-01

Gold bonding wires have been manufactured through multiple drawing steps with serial and reverse-direction drawing. The texture and microstructure of the gold bonding wires were characterized with X-ray diffraction and EBSD and compared with the predictions of finite element (FE) simulation. Initial fiber decreases during drawing and is replaced by fiber. The oriented grains are concentrated in the center and surface regions, whereas the oriented grains are located throughout the cross-section of the wire. Regions near the surface often exhibit the complex textures. A simplified forward and backward drawing process was modeled by FE analysis with ABAQUS/Standard TM . The simple two-step drawing process results in severe variation in shear strain under the surface and displays the opposite behavior in the shear components of the deformation gradient. The texture evolution was predicted using the deformation gradient calculated in the FE simulations together with a model of polycrystal plasticity. The and fibers are predicted to develop in the center part of the wire where homogeneous deformation occurs. The regions near the surface that experience repeated shear strain exhibit complex textures that deviate from the standard and fibers. The {1 1 2} and {1 1 1} components are prevalent in the higher shear strain regions. The variations of the anisotropic elastic directional moduli with position were also calculated

Reverse translated and gold standard continuous performance tests predict global cognitive performance in schizophrenia.

Science.gov (United States)

Bismark, Andrew W; Thomas, Michael L; Tarasenko, Melissa; Shiluk, Alexandra L; Rackelmann, Sonia Y; Young, Jared W; Light, Gregory A

2018-04-12

Attentional dysfunction contributes to functional impairments in schizophrenia (SZ). Sustained attention is typically assessed via continuous performance tasks (CPTs), though many CPTs have limited cross-species translational validity and place demands on additional cognitive domains. A reverse-translated 5-Choice Continuous Performance Task (5C-CPT) for human testing-originally developed for use in rodents-was designed to minimize demands on perceptual, visual learning, processing speed, or working memory functions. To-date, no studies have validated the 5C-CPT against gold standard attentional measures nor evaluated how 5C-CPT scores relate to cognition in SZ. Here we examined the relationship between the 5C-CPT and the CPT-Identical Pairs (CPT-IP), an established and psychometrically robust measure of vigilance from the MATRICS Consensus Cognitive Battery (MCCB) in a sample of SZ patients (n = 35). Relationships to global and individual subdomains of cognition were also assessed. 5C-CPT and CPT-IP measures of performance (d-prime) were strongly correlated (r = 0.60). In a regression model, the 5C-CPT and CPT-IP collectively accounted for 54% of the total variance in MCCB total scores, and 27.6% of overall cognitive variance was shared between the 5C-CPT and CPT-IP. These results indicate that the reverse translated 5C-CPT and the gold standard CPT-IP index a common attentional construct that also significantly overlaps with variance in general cognitive performance. The use of simple, cross-species validated behavioral indices of attentional/cognitive functioning such as the 5C-CPT could accelerate the development of novel generalized pro-cognitive therapeutics for SZ and related neuropsychiatric disorders.

Automated selection of trabecular bone regions in knee radiographs

International Nuclear Information System (INIS)

Podsiadlo, P.; Wolski, M.; Stachowiak, G. W.

2008-01-01

Osteoarthritic (OA) changes in knee joints can be assessed by analyzing the structure of trabecular bone (TB) in the tibia. This analysis is performed on TB regions selected manually by a human operator on x-ray images. Manual selection is time-consuming, tedious, and expensive. Even if a radiologist expert or highly trained person is available to select regions, high inter- and intraobserver variabilities are still possible. A fully automated image segmentation method was, therefore, developed to select the bone regions for numerical analyses of changes in bone structures. The newly developed method consists of image preprocessing, delineation of cortical bone plates (active shape model), and location of regions of interest (ROI). The method was trained on an independent set of 40 x-ray images. Automatically selected regions were compared to the ''gold standard'' that contains ROIs selected manually by a radiologist expert on 132 x-ray images. All images were acquired from subjects locked in a standardized standing position using a radiography rig. The size of each ROI is 12.8x12.8 mm. The automated method results showed a good agreement with the gold standard [similarity index (SI)=0.83 (medial) and 0.81 (lateral) and the offset=[-1.78, 1.27]x[-0.65,0.26] mm (medial) and [-2.15, 1.59]x[-0.58, 0.52] mm (lateral)]. Bland and Altman plots were constructed for fractal signatures, and changes of fractal dimensions (FD) to region offsets calculated between the gold standard and automatically selected regions were calculated. The plots showed a random scatter and the 95% confidence intervals were (-0.006, 0.008) and (-0.001, 0.011). The changes of FDs to region offsets were less than 0.035. Previous studies showed that differences in FDs between non-OA and OA bone regions were greater than 0.05. ROIs were also selected by a second radiologist and then evaluated. Results indicated that the newly developed method could replace a human operator and produces bone regions

Outpatient laparoscopic cholecystectomy: A new gold standard for cholecystectomy?

Directory of Open Access Journals (Sweden)

J. Bueno Lledó

Full Text Available Objective: to contribute our experience for five years in the implemetation of outpatient laparoscopic cholecystectomy (LC. Patients: between January 1999 and March 2004 we performed 504 outpatient LCs. We applied both exclusion and inclusion criteria, an anesthetic and surgical protocol, and discharge-specific criteria. Postoperative management in "fast track" regime. Postoperative period controlled by protocol, including phone calls after cholecystectomy. Results: the ambulatory percentage in the global series was 88.8%, and mean hospital stay was 6.1 hours. Fifty-one patients required overnight stays (10.1%, most of them for "social" causes. Five patients required admission (between 24 and 48 hours for different causes (conversion to laparotomy, intraoperative neumothorax, and postoperative medical complications. Six patients (1.1% were readmitted, and we observed 11.6% postoperative complications in the global series, with abdominal parietal pain being most frequent. Phone localization by 22.00 p.m. in the same day of surgery was 100% complete for outpatient cases. Postoperative surveillance within the first month after surgery was completed in 93.9%, and within th first year in 86.7% of patients. Conclusions: outpatient LC is safe and feasible, and probably represents a new "gold standard" in the treatment of symptomatic cholelithiasis.

Decision Making in the Management of Extracapsular Fractures of the Proximal Femur - is the Dynamic Hip Screw the Prevailing Gold Standard?

Science.gov (United States)

Jacob, Joshua; Desai, Ankit; Trompeter, Alex

2017-01-01

Currently, approximately half of all hip fractures are extracapsular, with an incidence as high as 50 in 100,000 in some countries. The common classification systems fail to explain the logistics of fracture classification and whether they all behave in the same manner. The Muller AO classification system is a useful platform to delineate stable and unstable fractures. The Dynamic hip screw (DHS) however, has remained the 'gold standard' implant of choice for application in all extracapsular fractures. The DHS relies on the integrity and strength of the lateral femoral wall as well as the postero-medial fragment. An analysis of several studies indicates significant improvements in design and techniques to ensure a better outcome with intramedullary nails. This article reviews the historical trends that helped to evolve the DHS implant as well as discussing if the surgeon should remain content with this implant. We suggest that the gold standard surgical management of extracapsular fractures can, and should, evolve.

Can We Create a "Gold Standard of Education" for Our Children through the "Advancement via Independent Determination (AVID) Program"?

Science.gov (United States)

Gaskins, Darlene

2014-01-01

We need to come together as a team and become one system of total quality improvement regarding the education of our nation's children. In order to achieve a gold standard in the education of our nation's children, leadership has to be willing to go against the status quo and build bridges for long-term sustainable change. In order to survive,…

76 FR 23470 - Version One Regional Reliability Standard for Transmission Operations

Science.gov (United States)

2011-04-27

...; Order No. 752] Version One Regional Reliability Standard for Transmission Operations AGENCY: Federal... Power Act, the Federal Energy Regulatory Commission approves regional Reliability Standard TOP-007-WECC... purpose of this regional Reliability Standard is to ensure that actual flows and associated scheduled...

A radiochemical study of gold electrodeposition kinetics in alkaline cyanide solutions

International Nuclear Information System (INIS)

Poshkus, D.; Agafonovas, G.; Zhebrauskas, A.

1995-01-01

Kinetics of gold electrodeposition from alkaline cyanide solutions was investigated by the use of labelled gold 195 atoms. The absorption of cyanide containing species from alkaline cyanide and dicyanoaurate solutions on a gold electrode by the use of labelled carbon atoms was investigated. Polarization curves of anodic dissolution and cathodic deposition of gold in alkaline cyanide solutions were obtained. The values of standard potential, exchange current density, transfer coefficient and standard polarization rate were determined from polarization curves. The errors in current density caused by the nuclear disintegration statistics were evaluated. 28 refs., 1 tab., 4 figs

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

Abstract. 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. PMID:25069006

Some developments in the extraction of gold from Witwatersrand ores

International Nuclear Information System (INIS)

Laxen, P.A.

1975-01-01

The extraction of gold from most ores of the Witwatersrand has been consistently high - approximately 95 per cent - for many years. The present high price of gold has stimulated research and development into potential improvements of the standard procedures. The occurrence of the gold and its association with other minerals is described briefly. The Witwatersrand reefs also contain uranium and pyrite, and some of the improvements to the standard gold-extraction process are associated with the recovery or concentration of one or both of these valuable constituents. For instance, the 'reverse-leach' process, in which acid treatment for the extraction of uranium precedes cyanidation, results in improved gold extraction. Some concentration techniques used on the present residues from cyanidation offer promise in improving the overall gold recoveries. Thucholite is an important carrier of residual gold, and its recovery from some residues by flotation appears to be economically justifiable. Wet high-intensity magnetic separation has given promising results, in the laboratory and on the pilot plant, for the recovery of both uranium and gold from a number of cyanide tailings. The benefits of gravity concentration and of the application of empirical modelling to the gold-extraction process have been demonstrated by a mining group. Some developments in instrumentation for control during cyanidation are discussed briefly [af

Realism and Imagination in Child Foreign-Language Productions: Three Reasons for an Early Exit from the "Gold Standard" of Personal Experience

Science.gov (United States)

Hong, Seongeun; Kellogg, David

2016-01-01

Teachers often assume that personal experience is a rich resource for classroom chat and a gold standard for meaningful exchange of information. But in this paper, we first present three kinds of reasons for suspecting that primary intersubjectivity--the "me and you" relationship in which personal experiences are directly exchanged…

Study on the determination of ore-formation age of primary gold ore

International Nuclear Information System (INIS)

Ying Junlong; Zhao Puyun; Guo Hong

1997-01-01

The accurate determination of gold ore-formation age and ore-source isotope composition are of important significance in the research on gold geology and prospecting. According to the summary of three year indoor and field work, the ore-formation ages and isotope compositions of some typical gold deposits were obtained: The age of gold ore of the Wuhuaaobao deposit in geo-syncline region north to the north margin of North-China paleo-land is 130-120 Ma corresponding to the Late-orogenic stage. The ore-formation age of the Saiwusu gold deposit in the southern platform region is 211 +- 15 Ma, recycling reworking of the old-land. The Hougou-Huangtuliang gold deposit located in the middle of the platform region is 243 +- 7 Ma old attributed to the regeneration ore-formation on the old-land. the age of Jiaojia-Rushan gold deposit in Eastern Shandong is 122.7 +- 3.4 Ma and 128 +- 23 Ma belonging to Yanshanian stage. The Babaoshan gold-silver deposit in Cathaysian old-land is 140 +- 5 Ma old originated from volcanic hydrothermal ore-formation

The determination, by x-ray-fluorescence spectrometry, of gold in activated charcoal

International Nuclear Information System (INIS)

Austen, C.E.

1977-01-01

A rapid method is described for the determination of gold in activated charcoal by X-ray-fluorescence spectrometry. Compensation for matrix effects is achieved by means of platinum that is added for use as an internal standard. Calibration is achieved by use of a series of synthetic standards that are made by the spiking of barren charcoal with gold and platinum. The limit of determination is about 8 p.p.m. of gold, and the relative standard deviation is 1,2 per cent at a concentration level of 2300 p.p.m

VALIDATION OF MITRAL VALVE ANNULUS DIMENSIONS MEASURED BY 2D TRANS-THORACIC ECHOCARDIOGRAPHY WITH GOLD STANDARD DIRECT INTRA-OPERATIVE MEASUREMENT

OpenAIRE

Praveen; Yadav; Ankur; Saket; Kaushal

2014-01-01

CONTEXT: Precise estimation of Mitral valve annulus dimensions preoperatively through Echocardiography is of paramount importance in replacement/repair surgeries. However a frequent disagreement was experienced between anticipated size of prosthetic valve based on echocardiography and actual valve size. This fact encouraged the authors to validate the measurements through echocardiography with gold-standard direct intra operative measurement. AIM: To compare the mitral val...

Determination of Commercial Karats on Gold Alloys for Jewellery

International Nuclear Information System (INIS)

Morales, S.E.A.

1986-12-01

An XRF method for the gold content determination in gold alloys was proposed and tested. Gold coins and ingot samples were analyzed. Monoelemental standards and two pint regression curves calculated with the NBSGSC program, Cd-109 annular source, Si-Li detector, 4096 channels analyzer and AXIL deconvolution software were employed. Good precision better than 1.5% and accuracy better than 2% were obtained. (author)

Regional analgesia for video-assisted thoracic surgery – a systematic review

DEFF Research Database (Denmark)

Julia Steinthorsdottir, Kristin; Wildgaard, Lorna; Jessen Hansen, Henrik

2013-01-01

there is no gold standard for regional analgesia for VATS. This systematic review aimed to assess different regional techniques in regards to effect on acute post-operative pain following VATS, with emphasis on VATS lobectomy. The systematic review of the PubMed, Cochrane Library and Embase databases yielded...... be demonstrated, but a guide of factors to include in future studies on regional analgesia for VATS is presented....

Gold film with gold nitride - A conductor but harder than gold

International Nuclear Information System (INIS)

Siller, L.; Peltekis, N.; Krishnamurthy, S.; Chao, Y.; Bull, S.J.; Hunt, M.R.C.

2005-01-01

The formation of surface nitrides on gold films is a particularly attractive proposition, addressing the need to produce harder, but still conductive, gold coatings which reduce wear but avoid the pollution associated with conventional additives. Here we report production of large area gold nitride films on silicon substrates, using reactive ion sputtering and plasma etching, without the need for ultrahigh vacuum. Nanoindentation data show that gold nitride films have a hardness ∼50% greater than that of pure gold. These results are important for large-scale applications of gold nitride in coatings and electronics

Neutron capture cross section standards for BNL-325

International Nuclear Information System (INIS)

Holden, N.E.

1980-01-01

The most common cross section standards for capture reactions in the thermal neutron energy region are gold, cobalt, and manganese. In preparation for the fourth edition of BNL-325, data on the thermal cross section and resonance integral were evaluated for these three standards. For gold, only measurements below the Bragg scattering cutoff were used and extrapolated to a neutron velocity of 2200 meters/second. A non 1/v correction due to the 4.9 eV resonance was made. The resonance integral is based on Jirlow's integral measurement and Tellier's parameters. The resonance integrals for cobalt and manganese are based solely on integral measurements because the capture widths of the first major resonance either vary by 20% in various measurements (cobalt), or have never been measured (manganese). Recommended thermal cross sections and resonance integrals are respectively gold: 98.65/plus or minus/0.9 barns, 1550/plus or minus/28 barns; cobalt: 37.18/plus or minus/0.06 barns, 74.2/plus or minus/2.0 barns and manganese: 13.3/plus or minus/0.2 barns, and 14.0/plus or minus/0.3 barns. 72 refs

A brief comparison of existing regional green building design standards in China

Science.gov (United States)

Wang, J.; Liu, Y.; Ren, J.; Cho, S.

2017-03-01

A large country with a variety of regional natural, cultural and economic conditions, China has established a number of green building design (GBD) standards both at national and regional (provincial and municipal) levels. Some researches have been conducted to review and compare such standards. The main aim was to provide valuable references for the establishment of new regionally specific GBD standards in different regions of the country. This paper introduces the preliminary results of the researches. The distribution, frameworks and content of the existing regional GBD standards are introduced and compared in relating to the regionally specific climate, resource, economic and cultural conditions. Conclusions are provided and further researches are recommended.

Determination of gold coating thickness measurement by using EDXRF

International Nuclear Information System (INIS)

Meor Yusoff Meor Sulaian; Masliana Muslimin; Fadlullah Jili Fursani

2005-01-01

The paper relates a study on the development of an analysis procedure for measuring the gold coating thickness using EDXRF technique. Gold coating thickness was measured by relating the counts under the Au L? peak its thickness value. In order to get a reasonably accurate result, a calibration graph was plotted using five gold-coated reference standards of different thickness. The calibration graph shows a straight line for thin coating measurement until 0.9 μm. Beyond this the relationship was not linear and this may be resulted from the self-absorption effect. Quantitative analysis was also performed on two different samples of gold coated jewelry and a phone connector. Result from the phone connector analysis seems to agree with the manufacturer gold coating value. From the analysis of gold-coated jewelry it had been able to differentiate the two articles as gold wash and gold electroplated. (Author)

Sedentary nestlings of Wood Stork as monitors of mercury contamination in the gold mining region of the Brazilian Pantanal

Energy Technology Data Exchange (ETDEWEB)

Nassif Del Lama, Silvia, E-mail: dsdl@ufscar.br [Laboratorio Genetica de Aves, Departamento de Genetica e Evolucao, Universidade Federal de Sao Carlos, Rodovia Washington Luis km 235, 13565-905 Sao Carlos, Sao Paulo (Brazil); Dosualdo Rocha, Cristiano [Laboratorio Genetica de Aves, Departamento de Genetica e Evolucao, Universidade Federal de Sao Carlos, Rodovia Washington Luis km 235, 13565-905 Sao Carlos, Sao Paulo (Brazil); Figueiredo Jardim, Wilson [Institute of Chemistry, State University of Campinas, P.O. Box 6154, 13083-970 Sao Paulo (Brazil); Tsai, Jo-Szu; Frederick, Peter Crawford [Department of Wildlife Ecology and Conservation, P.O. Box 110430, University of Florida, Gainesville, FL 32611 (United States)

2011-11-15

Sedentary organisms that are at top trophic levels allow inference about the level of local mercury contamination. We evaluated mercury contamination in feather tissue of nestling Wood Storks (Mycteria americana), sampled in different parts of the Brazilian Pantanal that were variably polluted by mercury releases from gold mining activities. Levels of mercury in feathers sampled in seven breeding colonies were determined by atomic absorption spectroscopy, and the mean value of mercury concentration was 0.557 {mu}g/g, dry weight (n=124), range 0.024-4.423 {mu}g/g. From this total sample, 21 feathers that represent 30% of nestlings collected in Porto da Fazenda and Tucum colonies, in the northern region, ranged from 1.0 to 4.43 {mu}g/g, dry weight (median value=1.87 {mu}g/g). We found significant differences among regions (H=57.342; p=0<0.05). Results suggest that permanently flooded areas, or along mainstream rivers are more contaminated by mercury than dry areas, regardless of the distance from the gold mining center, which is located in the northern Pantanal. Highest values found in nestlings feathers were similar to those found in feathers of adult birds and in tissues of adult mammals that are less sedentary and were captured in the same region of Pantanal. These findings indicate that mercury released has been biomagnified and it is present in high concentrations in tissues of top consumers. We suggest a program to monitor mercury availability in this ecosystem using sedentary life forms of top predators like Wood Storks or other piscivorous birds. - Highlights: Black-Right-Pointing-Pointer Sedentary stork nestlings were used for the first time to show local mercury contamination of Pantanal. Black-Right-Pointing-Pointer Differences were found among regions but they are not explained only by distance from the gold mining. Black-Right-Pointing-Pointer Permanently flooded areas and areas along mainstream rivers are more contaminated than dry areas. Black

Sedentary nestlings of Wood Stork as monitors of mercury contamination in the gold mining region of the Brazilian Pantanal

International Nuclear Information System (INIS)

Nassif Del Lama, Silvia; Dosualdo Rocha, Cristiano; Figueiredo Jardim, Wilson; Tsai, Jo-Szu; Frederick, Peter Crawford

2011-01-01

Sedentary organisms that are at top trophic levels allow inference about the level of local mercury contamination. We evaluated mercury contamination in feather tissue of nestling Wood Storks (Mycteria americana), sampled in different parts of the Brazilian Pantanal that were variably polluted by mercury releases from gold mining activities. Levels of mercury in feathers sampled in seven breeding colonies were determined by atomic absorption spectroscopy, and the mean value of mercury concentration was 0.557 μg/g, dry weight (n=124), range 0.024–4.423 μg/g. From this total sample, 21 feathers that represent 30% of nestlings collected in Porto da Fazenda and Tucum colonies, in the northern region, ranged from 1.0 to 4.43 μg/g, dry weight (median value=1.87 μg/g). We found significant differences among regions (H=57.342; p=0<0.05). Results suggest that permanently flooded areas, or along mainstream rivers are more contaminated by mercury than dry areas, regardless of the distance from the gold mining center, which is located in the northern Pantanal. Highest values found in nestlings feathers were similar to those found in feathers of adult birds and in tissues of adult mammals that are less sedentary and were captured in the same region of Pantanal. These findings indicate that mercury released has been biomagnified and it is present in high concentrations in tissues of top consumers. We suggest a program to monitor mercury availability in this ecosystem using sedentary life forms of top predators like Wood Storks or other piscivorous birds. - Highlights: ► Sedentary stork nestlings were used for the first time to show local mercury contamination of Pantanal. ► Differences were found among regions but they are not explained only by distance from the gold mining. ► Permanently flooded areas and areas along mainstream rivers are more contaminated than dry areas. ► Mercury has been biomagnified in Pantanal and it is found in high concentrations in top

Consent for routine neonatal procedures: A study of practices in Irish neonatal units. How do we compare with the gold standard BAPM guidelines?

Science.gov (United States)

Ryan, M A; Ryan, C A; Dempsey, E; O'Connell, R

2017-06-09

The Irish National Consent Policy (NCP) proposes that the legal requirement for consent extends to all forms of interventions, investigations and treatment, carried out on or behalf of the Health Service Executive (HSE). This study employs a quantitative descriptive approach to investigate the practices for obtaining consent for an identified group of routine neonatal procedures in neonatal facilities throughout Ireland. The BAPM (British Association of Perinatal Medicine) guidelines were identified as 'gold standard' for the purposes of this study. The results indicated a lack of consistency between participating units pertaining to the modes of consent utilised and notable variances from 'gold standard' guidelines. Unanimity was evident for 3 procedures only (administering BCG, 6-in-1, and donor breast milk to infant). Significant findings related to EEG with video recordings, MRI/CT and gastro intestinal imaging, screening of an infant with suspected substance abuse or retinopathy of prematurity screening (ROP), administration of Vitamin K, and the carrying out of a lumbar puncture.

Determination of gold in gold ores

International Nuclear Information System (INIS)

Keedy, C.R.; Parson, L.; Shen, J.

1989-01-01

The gold content of placer gold flakes and gold bearing ores was determined by instrumental and radiochemical neutron activation analysis, respectively. It was discovered that significant errors result in the instrumental method for gold flakes as small as 10 mg due to sample self-absorption of neutrons during irradiation. Reliable results were obtained for both ore samples and gold flakes by dissolving the samples in aqua regia prior to irradiation. (author) 7 refs.; 3 tabs

Phonon assisted thermophoretic motion of gold nanoparticles inside carbon nanotubes

DEFF Research Database (Denmark)

Schoen, Philipp A.E.; Walther, Jens Honore; Poulikakos, Dimos

2007-01-01

The authors investigate the thermally driven mass transport of gold nanoparticles confined inside carbon nanotubes using molecular dynamics simulations. The observed thermophoretic motion of the gold nanoparticles correlates with the phonon dispersion exhibited by a standard carbon nanotube and...

Analysis of gold in jewellery articles by energy dispersive XRF

International Nuclear Information System (INIS)

Meor Yusoff Meor Sulaiman; Latifah Amin

2001-01-01

The value of a precious metal article is much related to its fineness. For gold assay, conventional fire assay technique has been used as the standard technique for more than 500 years. Alternative modern techniques like energy dispersive x-ray fluorescence can also be used in the determination of gold purity. Advantages of this technique compared to the conventional method including non-destructive analysis, does not use any toxic or hazardous chemicals, automatic computer control and is user friendly, requires minimum number of personnel, shorter analysis time and able to determine associated elements in the metal. Analysis was performed on different sizes and purity of gold. Comparison results for the analysis using different reference standards show small differences between technique and its certified value. The technique also gives small standard deviation value in its repeatability test. (Author)

Heavy metal pollution in soil associated with a large-scale cyanidation gold mining region in southeast of Jilin, China.

Science.gov (United States)

Chen, Mo; Lu, Wenxi; Hou, Zeyu; Zhang, Yu; Jiang, Xue; Wu, Jichun

2017-01-01

Different gold mining and smelting processes can lead to distinctive heavy metal contamination patterns and results. This work examined heavy metal pollution from a large-scale cyanidation gold mining operation, which is distinguished from artisanal and small-scale amalgamation gold mining, in Jilin Province, China. A total of 20 samples including one background sample were collected from the surface of the mining area and the tailings pond in June 2013. These samples were analyzed for heavy metal concentrations and degree of pollution as well as sources of Cr, Cu, Zn, Pb, Ni, Cd, As, and Hg. The mean concentrations of Pb, Hg, and Cu (819.67, 0.12, and 46.92 mg kg -1 , respectively) in soil samples from the gold mine area exceeded local background values. The mean Hg content was less than the first-class standard of the Environmental Quality for Soils, which suggested that the cyanidation method is helpful for reducing Hg pollution. The geochemical accumulation index and enrichment factor results indicated clear signs that enrichment was present for Pb, Cu, and Hg, with the presence of serious Pb pollution and moderate presence to none of Hg and Cu pollution. Multivariate statistical analysis showed that there were three metal sources: (1) Pb, Cd, Cu, and As came from anthropogenic sources; (2) Cr and Zn were naturally occurring; whereas (3) Hg and Ni had a mix of anthropogenic and natural sources. Moreover, the tailings dam plays an important role in intercepting the tailings. Furthermore, the potential ecological risk assessment results showed that the study area poses a potentially strong risk to the ecological health. Furthermore, Pb and Hg (due to high concentration and high toxicity, respectively) are major pollutants on the risk index, and both Pb and Hg pollution should be of great concern at the Haigou gold mines in Jilin, China.

40 CFR 440.140 - Applicability; description of the gold placer mine subcategory.

Science.gov (United States)

2010-07-01

... separation methods for recovering gold from placer deposits. (b) The provisions of this subpart M are not... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Applicability; description of the gold... AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Gold...

Chinese Gold Miners of the Mid-Columbia Region; TOPICAL

International Nuclear Information System (INIS)

J. J. Sharpe

1999-01-01

This report was compiled to provide historical information to assist cultural resources personnel to identify features and artifacts that might relate to Chinese placer mining along the Hanford Reach of the Columbia River. Historical information indicates that Chinese miners pursued placer gold along the Hanford Reach

Imaging of the optic disk in caring for patients with glaucoma: ophthalmoscopy and photography remain the gold standard.

Science.gov (United States)

Spaeth, George L; Reddy, Swathi C

2014-01-01

Optic disk imaging is integral to the diagnosis and treatment of patients with glaucoma. We discuss the various forms of imaging the optic nerve, including ophthalmoscopy, photography, and newer imaging modalities, including optical coherence tomography (OCT), confocal scanning laser ophthalmoscopy (HRT), and scanning laser polarimetry (GDx), specifically highlighting their benefits and disadvantages. We argue that ophthalmoscopy and photography remain the gold standard of imaging due to portability, ease of interpretation, and the presence of a large database of images for comparison. Copyright © 2014 Elsevier Inc. All rights reserved.

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.

Absorption Spectra of Gold Nanoparticle Suspensions

Science.gov (United States)

Anan'eva, M. V.; Nurmukhametov, D. R.; Zverev, A. S.; Nelyubina, N. V.; Zvekov, A. A.; Russakov, D. M.; Kalenskii, A. V.; Eremenko, A. N.

2018-02-01

Three gold nanoparticle suspensions are obtained, and mean radii in distributions - (6.1 ± 0.2), (11.9 ± 0.3), and (17.3 ± 0.7) nm - are determined by the transmission electron microscopy method. The optical absorption spectra of suspensions are obtained and studied. Calculation of spectral dependences of the absorption index of suspensions at values of the gold complex refractive index taken from the literature showed a significant deviation of experimental and calculated data in the region of 450-800 nm. Spectral dependences of the absorption of suspensions are simulated within the framework of the Mie-Drude theory taking into account the interband absorption in the form of an additional term in the imaginary part of the dielectric permittivity of the Gaussian type. It is shown that to quantify the spectral dependences in the region of the plasmon absorption band of nanoparticles, correction of the parameters of the interband absorption is necessary in addition to the increase of the relaxation parameter of the Drude theory. Spectral dependences of the dielectric permittivity of gold in nanodimensional state are refined from the solution of the inverse problem. The results of the present work are important for predicting the special features of operation of photonic devices and optical detonators based on gold nanoparticles.

Characterisation of a thiosulphate-sulphite gold electrodeposition process

International Nuclear Information System (INIS)

J-Liew, M.; Sobri, S.; Roy, S.

2005-01-01

Electrodeposition of soft gold is an important process in the fabrication of micro devices for electronics, optics etc. Traditional gold electroplating is based on a gold cyanide process which is not applicable for the stringent requirements in state of the art micro device manufacture. Newcastle University has been involved in the development of an industrial process based on a mixed ligand electrolyte-the gold thiosulphate-sulphite system. Here we present methods for the formulation of this electrolyte in the laboratory which ensure bath stability and process compatibility. In addition, we have carried out spectrophotometry to elucidate the possible reasons of its chemical stability. Standard rotating disk and cyclic voltammetry has been carried out to determine the electrochemical behaviour of the gold thiosulphate-sulphite system. The changes in electrochemical behaviour as the bath ages are also discussed

Elevated rates of gold mining in the Amazon revealed through high-resolution monitoring.

Science.gov (United States)

Asner, Gregory P; Llactayo, William; Tupayachi, Raul; Luna, Ernesto Ráez

2013-11-12

Gold mining has rapidly increased in western Amazonia, but the rates and ecological impacts of mining remain poorly known and potentially underestimated. We combined field surveys, airborne mapping, and high-resolution satellite imaging to assess road- and river-based gold mining in the Madre de Dios region of the Peruvian Amazon from 1999 to 2012. In this period, the geographic extent of gold mining increased 400%. The average annual rate of forest loss as a result of gold mining tripled in 2008 following the global economic recession, closely associated with increased gold prices. Small clandestine operations now comprise more than half of all gold mining activities throughout the region. These rates of gold mining are far higher than previous estimates that were based on traditional satellite mapping techniques. Our results prove that gold mining is growing more rapidly than previously thought, and that high-resolution monitoring approaches are required to accurately quantify human impacts on tropical forests.

The 'Thin film of gold': monetary rules and policy credibility

OpenAIRE

Niall Ferguson; Moritz Schularick

2012-01-01

This paper asks whether developing countries can reap credibility gains from submitting policy to a strict monetary rule. Following earlier work, we look at the gold standard era (1880-1914) as a "natural experiment" to test whether adoption of a rule-based monetary framework such as the gold standard increased policy credibility. On the basis of the largest possible dataset covering almost sixty independent and colonial borrowers in the London market, we challenge the traditional view that g...

SU-E-I-59: Investigation of the Usefulness of a Standard Deviation and Mammary Gland Density as Indexes for Mammogram Classification.

Science.gov (United States)

Takarabe, S; Yabuuchi, H; Morishita, J

2012-06-01

To investigate the usefulness of the standard deviation of pixel values in a whole mammary glands region and the percentage of a high- density mammary glands region to a whole mammary glands region as features for classification of mammograms into four categories based on the ACR BI-RADS breast composition. We used 36 digital mediolateral oblique view mammograms (18 patients) approved by our IRB. These images were classified into the four categories of breast compositions by an experienced breast radiologist and the results of the classification were regarded as a gold standard. First, a whole mammary region in a breast was divided into two regions such as a high-density mammary glands region and a low/iso-density mammary glands region by using a threshold value that was obtained from the pixel values corresponding to a pectoral muscle region. Then the percentage of a high-density mammary glands region to a whole mammary glands region was calculated. In addition, as a new method, the standard deviation of pixel values in a whole mammary glands region was calculated as an index based on the intermingling of mammary glands and fats. Finally, all mammograms were classified by using the combination of the percentage of a high-density mammary glands region and the standard deviation of each image. The agreement rates of the classification between our proposed method and gold standard was 86% (31/36). This result signified that our method has the potential to classify mammograms. The combination of the standard deviation of pixel values in a whole mammary glands region and the percentage of a high-density mammary glands region to a whole mammary glands region was available as features to classify mammograms based on the ACR BI- RADS breast composition. © 2012 American Association of Physicists in Medicine.

Biosynthesis of gold nanoparticles using diatoms-silica-gold and EPS-gold bionanocomposite formation

OpenAIRE

Schröfel, Adam; Kratošová, Gabriela; Bohunická, Markéta; Dobročka, Edmund; Vávra, Ivo

2011-01-01

Novel synthesis of gold nanoparticles, EPS-gold, and silica-gold bionanocomposites by biologically driven processes employing two diatom strains (Navicula atomus, Diadesmis gallica) is described. Transmission electron microscopy (TEM) and electron diffraction analysis (SAED) revealed a presence of gold nanoparticles in the experimental solutions of the diatom culture mixed with tetrachloroaureate. Nature of the gold nanoparticles was confirmed by X-ray diffraction studies. Scanning electron m...

Relation of Market Where Gold Supply And Demand is Intensive With Finance Sector and Analyze Of Present Market Structure in Terms Of Socio-Economic: A Study Based On Survey in Şanlıurfa and in the Region

Directory of Open Access Journals (Sweden)

Mehmet Cihangir

2010-03-01

Full Text Available One of the provinces where gold is purchased and sold mostly is Şanlıurfa. Especially trading of gold mostly in some special days following İstanbul and Ankara has made necessary that jewelry sector in this province where gold is purchased and sold is put under the scope and thereby examination of the contribution of gold to region economy as well as its other aspects. Within this scope a detailed questionnaire study to search gold and jewelry sector in Şanlıurfa in point of social, cultural and economical effects have been carried out and it has been aimed to explain these effectsdirectly from explanations of parties of incident. Considering the inevitability of emergence of some problems in a region where such extensive sale and purchase is made, the problems seen mostly have been determined and proposals regarding the solution of these have been made. In addition it has also been aimed to observe perception manner of gold and its contribution to region economy as a investment vehicle in the region. Especially the damage of misleading of credit card in sector has been tried to determine and made solution recommendations to the problem. It has been pointed out on the benefits in case the gold called mattress and considered its effect to economy is little is gained to Şanlıurfa economy.

Principal types of precambrian uranium-gold deposits and their metallogenetic characteristics in China

International Nuclear Information System (INIS)

Liang Liang; Zhong Zhiyun.

1988-01-01

Principal types of Precambrian uranium-gold deposits are follows: paleo-conglomerate uranium-deposit, stratified or strata-bound uranium-gold deposit, unconformity-related uranium deposit (no or seldem gold) and greenstone gold deposit. The main types of gold deposits in China is greenstone one which is characterized by later age, high grade metamorphism and a large time difference between diagenesis of host rocks and gold metallogenesis. Gold deposits are spatially distributed in the uplift area, whereas uranium deposits are distributed in the downfaulted belt. Furthermore, both uranium and gold deposits are controlled by regional fractures

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.

Features of Inner Structure of Placer Gold of the North-Eastern Part Siberian Platform

Science.gov (United States)

Gerasimov, Boris; Zhuravlev, Anatolii; Ivanov, Alexey

2017-12-01

Mineral and raw material base of placer and ore gold is based on prognosis evaluation, which allows to define promising areas regarding gold-bearing deposit prospecting. But there are some difficulties in gold primary source predicting and prospecting at the North-east Siberian platform, because the studied area is overlapped by thick cover of the Cenozoic deposits, where traditional methods of gold deposit prospecting are ineffective. In this connection, detailed study of typomorphic features of placer gold is important, because it contains key genetic information, necessary for development of mineralogical criteria of prognosis evaluation of ore gold content. Authors studied mineralogical-geochemical features of placer gold of the Anabar placer area for 15 years, with a view to identify indicators of gold, typical for different formation types of primary sources. This article presents results of these works. In placer regions, where primary sources of gold are not identified, there is need to study typomorphic features of placer gold, because it contains important genetic information, necessary for the development of mineralogical criteria of prognosis evaluation of ore gold content. Inner structures of gold from the Anabar placer region are studied, as one of the diagnostic typomorphic criteria as described in prominent method, developed by N.V. Petrovskaya [1980]. Etching of gold was carried out using reagent: HCl + HNO3 + FeCl3 × 6H2O + CrO3 +thioureat + water. Identified inner structures wer studied in details by means of scanning electron microscope JEOL JSM-6480LV. Two types of gold are identified according to the features of inner structure of placer gold of the Anabar region. First type - medium-high karat fine, well processed gold with significantly changed inner structure. This gold is allochthonous, which was redeposited many times from ancient intermediate reservoirs to younger deposits. Second type - low-medium karat, poorly rounded gold with

Green Gold

International Nuclear Information System (INIS)

Salamandra Martinez, Carlos

2004-01-01

The main purpose of this work is to offer a general panoramic of the processes or experiences pilot that are carried out in the Project Green Gold, as strategy of environmental sustainability and organizational invigoration in Choco, especially in the 12 communities of the municipalities of Tado and Condoto. It is also sought to offer a minimum of information on the techniques of handmade production and to show the possibilities to carry out in a rational way the use and use of the natural resources. The Project Green Gold is carried out by the Corporation Green Gold (COV) and co-financed with resources of international and national character, the intervention of the financial resources it achievement mainly for the use of clean processes in the extraction stages and metals benefit. The project is centered primarily in the absence of use of products or toxic substances as the mercury, fair trade, organizational invigoration, execution of 11 approaches and certification of the metals Gold and Platinum. The COV, it has come executing the proposal from the year 2001 with the premise of contributing to the balance between the rational exploitation of the natural resources and the conservation of the environment in the Choco. In the project they are used technical handmade characteristic of the region framed inside the mining activity and production activities are diversified in the productive family units. Those producing with the support of entities of juridical character, specify the necessary game rules for the extraction and products commercialization

A locking compression plate versus the gold-standard non-locking plate with lag screw for first metatarsophalangeal fusion: A biomechanical comparison.

Science.gov (United States)

Mandell, Daniel; Karbassi, John; Zhou, Hanbing; Burroughs, Brian; Aurigemma, Philip; Patel, Abhay R

2018-03-01

The treatment of end-stage first metatarso-phalangeal joint (MTP) arthritis has been arthrodesis. A dorsal non-locking plate with a lag screw has been the standard traditional fixation method. This study compares the biomechanical strength of a locking compression plate (LCP) with and without internal compression versus this known gold standard. In group 1, six matched pairs of cadaver great toes were used to compare the standard non-locking dorsal plate and 3.5mm lag screw to an anatomic locking compression plate in which a lag screw was utilized rather than the internal compression features of the plate. In group 2, another six matched pairs of cadaver great toes were used to compare the gold standard to the locking compression plate, utilizing the plate's internal compression feature instead of a lag screw. A material testing system (MTS) machine applied loads to the MTP joints and measured displacement and stiffness of the constructs. The stiffness of the constructs (Young's modulus) was calculated from the force-displacement curves, and the displacement was measured. The locking compression plate group that used the compression features of the plate, without the lag screw, had less joint displacement and higher stiffness than control (p<0.05). The same plating construct in which a lag screw was used rather than internal compression of the plate was found to be stiffer than the control (p<0.05), but displacement was not statistically significant. The results suggest that a locking compression plate alone provides the stiffest construct for a first MTP joint fusion. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hallmarking as an essential need of gold industry

International Nuclear Information System (INIS)

Mahmood, K.; Alam, S.; Ahmed, T.

2006-01-01

As gold is a soft metal, for Jewellery making it is alloyed with Silver or Copper so that its strength may increase. Other main alloying elements include; Zinc, Cadmium and Nickel. These alloying elements help to reduce cost, improve appearance and to improve chemical properties of gold. The percentage of alloying elements determines the caratages of gold. The gold Jewellery sold in local market is often under-carated. In order to improve the quality of product sold, complete quality assessment of gold should be done. A complete quality assessment includes both Assaying and Hallmarking. Assaying is the analysis of an individual sample of gold from a customer to find out it's composition and Hallmarking refers to physically marking: a piece of Jewellery according to specific laws to certify the purity of metal. In this paper we have assessed and compared the quality of locally manufactured gold ornaments and its alloying components with international market as well as standards of gold and its alloys. And as Hallmarking is one of the main strategic initiatives to improve the quality of product sold for domestic and export consumption, this paper discusses the necessary steps leading to Hallmarking. We have used micro-XRF spectrometer for assaying and Laser Engraving machine for the purpose of Hallmarking. (author)

Lamellar multilayer hexadecylaniline-modified gold nanoparticle ...

Indian Academy of Sciences (India)

standard Wilhelmy plate was used for surface pressure sensing. Multilayer ... carried out on a JEOL model 1200EX instrument operated at an accelerating voltage of ... the gold nanoparticles within domains (and reorganization of the domains ...

Testing Pneumonia Vaccines in the Elderly: Determining a Case Definition for Pneumococcal Pneumonia in the Absence of a Gold Standard.

Science.gov (United States)

Jokinen, Jukka; Snellman, Marja; Palmu, Arto A; Saukkoriipi, Annika; Verlant, Vincent; Pascal, Thierry; Devaster, Jeanne-Marie; Hausdorff, William P; Kilpi, Terhi M

2017-12-15

Clinical assessments of vaccines to prevent pneumococcal (Pnc) community-acquired pneumonia (CAP) require sensitive and specific case definitions, but there is no gold standard diagnostic test. To develop a new case definition suitable for vaccine efficacy studies, we applied latent class analysis (LCA) to the results from seven diagnostic tests for Pnc etiology on clinical specimens from 323 elderly radiologically-confirmed pneumonia cases enrolled in The Finnish Community-Acquired Pneumonia Epidemiology study during 2005-2007. Compared to the conventional use of LCA, which is mainly to determine sensitivities and specificities of different tests, we instead used LCA as an appropriate instrument to predict the probability of Pnc etiology for each CAP case based on their test profiles, and utilized the predictions to minimize the sample size that would be needed for a vaccine efficacy trial. When compared to the conventional laboratory criteria of encapsulated Pnc in blood culture or in high-quality sputum culture or urine antigen positivity, our optimized case definition for PncCAP resulted in a trial sample size which was almost 20,000 subjects smaller. We believe that our novel application of LCA detailed here to determine a case definition for PncCAP could also be similarly applied to other diseases without a gold standard. © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health.

Annotated chemical patent corpus: a gold standard for text mining.

Directory of Open Access Journals (Sweden)

Saber A Akhondi

Full Text Available Exploring the chemical and biological space covered by patent applications is crucial in early-stage medicinal chemistry activities. Patent analysis can provide understanding of compound prior art, novelty checking, validation of biological assays, and identification of new starting points for chemical exploration. Extracting chemical and biological entities from patents through manual extraction by expert curators can take substantial amount of time and resources. Text mining methods can help to ease this process. To validate the performance of such methods, a manually annotated patent corpus is essential. In this study we have produced a large gold standard chemical patent corpus. We developed annotation guidelines and selected 200 full patents from the World Intellectual Property Organization, United States Patent and Trademark Office, and European Patent Office. The patents were pre-annotated automatically and made available to four independent annotator groups each consisting of two to ten annotators. The annotators marked chemicals in different subclasses, diseases, targets, and modes of action. Spelling mistakes and spurious line break due to optical character recognition errors were also annotated. A subset of 47 patents was annotated by at least three annotator groups, from which harmonized annotations and inter-annotator agreement scores were derived. One group annotated the full set. The patent corpus includes 400,125 annotations for the full set and 36,537 annotations for the harmonized set. All patents and annotated entities are publicly available at www.biosemantics.org.

Nuclear orientation experiments concerning odd-A gold isotopes

International Nuclear Information System (INIS)

Ligthart, H.J.

1982-01-01

This thesis describes nuclear spectroscopy aspects of nuclear orientation in the odd-A gold isotopes 191 Au, 193 Au, 195 Au and 197 Au. These isotopes lie in a transitional region between the spherical nuclei in the lead region and the strongly deformed rare earth isotopes. Following a general introduction to nuclear orientation, the experimental arrangement is described. A new technique is presented that applies in-beam recoil implantation inside the refrigerator itself and this was applied to the case of 191 Au. The three other gold isotopes were oriented using a conventional dilution refrigerator. The nuclear orientation experiments concerning 11/2 - isomers of the isotopes are described. The long-lived isomeric states were oriented using the large hyperfine field of gold in iron. Higher lying levels were studied by nuclear orientation of the Hg parent states. (Auth./C.F.)

South African gold and uranium ore mining in 1976

International Nuclear Information System (INIS)

Hentrich, W.

1977-01-01

1976 was a difficult year for the South African gold and uranium ore mining industry, the region of Witwatersrand (Transvaal province) producing some 75% of all the gold mined in the western world besides being an important producer of uranium oxide. Despite the gold production, declining since 1971, not showing a downward tendency anymore as far as the quantity was concerned, the economic result, however, deteriorated as a consequence of continuously falling gold prices, but also on account of the inflationary rise in wages and the prices for energy and materials. Much higher prices for uranium oxide, which some mines produce as interim products from the 'degolded' slurries of their gold ore leaching plants, improved the economic overall result only to a small degree. (orig.) [de

Reconsidering the H&E stain as the gold standard in assessing the depth of burn wounds.

Science.gov (United States)

Rosenberg, Arlene S

2017-12-01

While histological examination is considered by most as the gold standard for burn depth assessment, it has no practical use in the clinical setting. It has, however, been used in the research setting, as a mean for evaluating emerging techniques of depth measurement. Due to the limitations of the H&E stain, other stains have also been explored, such as lactate dehydrogenase (LDH), as presented in this issue, in "Improving the Histologic Characterization of Burn Depth." As the determination of burn depth is not a typical subject in dermatopathology, a summary of selected techniques and the possible role for the LDH stain in future research, is described herein. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Assessment of modified gold surfaced titanium implants on skeletal fixation

DEFF Research Database (Denmark)

Zainali, Kasra; Danscher, Gorm; Jakobsen, Thomas

2013-01-01

shown to liberate gold ions through the process termed dissolucytosis. Furthermore, gold ions are known to act in an anti-inflammatory manner by inhibiting cellular NF-κB-DNA binding. The present study investigated whether partial coating of titanium implants could augment early osseointegration...... and increase mechanical fixation. Cylindrical porous coated Ti-6Al4V implants partially coated with metallic gold were inserted in the proximal region of the humerus in ten canines and control implants without gold were inserted in contralateral humerus. Observation time was 4 weeks. Biomechanical push out...

Gold processing residue from Jacobina Basin: chemical and physical properties

OpenAIRE

Lima, Luiz Rogério Pinho de Andrade; Bernardez, Letícia Alonso; Barbosa, Luís Alberto Dantas

2007-01-01

p. 848-852 Gold processing residues or tailings are found in several areas in the Itapicuru River region (Bahia, Brazil), and previous studies indicated significant heavy metals content in the river sediments. The present work focused on an artisanal gold processing residue found in a site from this region. Samples were taken from the processing residue heaps and used to perform a physical and chemical characterization study using X-ray diffraction, scanning electron microscopy, neutron...

Cripple Creek and other alkaline-related gold deposits in the Southern Rocky Mountains, USA: Influence of regional tectonics

Science.gov (United States)

Kelley, K.D.; Ludington, S.

2002-01-01

opposed to deposits to the south. Deep-seated structures of regional extent that formed during the Proterozoic allowed the magmas to rise to shallow crustal levels. Proterozoic sites of intrusions at 1.65, 1.4, and 1.1 Ga were also important precursors to alkaline-related gold deposits. Many of the larger gold deposits are located at sites of Proterozoic intrusions, and are localized at the intersection of northeast-trending ductile shear zones formed during Mesoproterozoic deformation, and an important north-trending fault formed during 1.1 Ga rifting.

Elemental analysis of gold coins by particle induced X-ray emission (PIXE)

International Nuclear Information System (INIS)

Ferreira, G.P.; Gil, F.B.

1981-01-01

A Van de Graaff accelerator of 2 MeV energy was used for quantitative analysis of gold coins of the eighteenth and nineteenth centuries by the PIXE method. The results reproduce well the known legal title of the coins. However, for confirmation, a small set of Au-Ag-Cu and Au-Cu standards was also analysed. Again, the known composition of the standards was reasonably reproduced. In this way the authors think that the PIXE method is quite adequate for absolutely non-destructive analysis of gold alloy artifacts with no need of standards. (author)

Outpatient laparoscopic cholecystectomy: A new gold standard for cholecystectomy? Colecistectomía laparoscópica ambulatoria: ¿El nuevo "gold standard" de la colecistectomía?

Directory of Open Access Journals (Sweden)

J. Bueno Lledó

2006-01-01

Full Text Available Objective: to contribute our experience for five years in the implemetation of outpatient laparoscopic cholecystectomy (LC. Patients: between January 1999 and March 2004 we performed 504 outpatient LCs. We applied both exclusion and inclusion criteria, an anesthetic and surgical protocol, and discharge-specific criteria. Postoperative management in "fast track" regime. Postoperative period controlled by protocol, including phone calls after cholecystectomy. Results: the ambulatory percentage in the global series was 88.8%, and mean hospital stay was 6.1 hours. Fifty-one patients required overnight stays (10.1%, most of them for "social" causes. Five patients required admission (between 24 and 48 hours for different causes (conversion to laparotomy, intraoperative neumothorax, and postoperative medical complications. Six patients (1.1% were readmitted, and we observed 11.6% postoperative complications in the global series, with abdominal parietal pain being most frequent. Phone localization by 22.00 p.m. in the same day of surgery was 100% complete for outpatient cases. Postoperative surveillance within the first month after surgery was completed in 93.9%, and within th first year in 86.7% of patients. Conclusions: outpatient LC is safe and feasible, and probably represents a new "gold standard" in the treatment of symptomatic cholelithiasis.Objetivo: aportar nuestra experiencia durante cinco años en la implantación de la colecistectomía laparoscópica (CL en un programa de cirugía mayor ambulatoria (CMA. Pacientes: entre enero de 1999 y marzo de 2004, se realizaron 504 CL consecutivas en régimen ambulatorio. Se aplicaron criterios de exclusión e inclusión, un procedimiento anestésico-quirurgico protocolizado, y criterios específicos al alta hospitalaria. El manejo postoperatorio se realizó en régimen de "fast track" o de recuperación rápida. Seguimiento postoperatorio estricto mediante protocolo de revisiones, incluido localizaci

Leishmania Infection: Laboratory Diagnosing in the Absence of a “Gold Standard”

Science.gov (United States)

Rodríguez-Cortés, Alhelí; Ojeda, Ana; Francino, Olga; López-Fuertes, Laura; Timón, Marcos; Alberola, Jordi

2010-01-01

There is no gold standard for diagnosing leishmaniases. Our aim was to assess the operative validity of tests used in detecting Leishmania infection using samples from experimental infections, a reliable equivalent to the classic definition of gold standard. Without statistical differences, the highest sensitivity was achieved by protein A (ProtA), immunoglobulin (Ig)G2, indirect fluorescenece antibody test (IFAT), lymphocyte proliferation assay, quantitative real-time polymerase chain reaction of bone marrow (qPCR-BM), qPCR-Blood, and IgG; and the highest specificity by IgG1, IgM, IgA, qPCR-Blood, IgG, IgG2, and qPCR-BM. Maximum positive predictive value was obtained simultaneously by IgG2, qPCR-Blood, and IgG; and maximum negative predictive value by qPCR-BM. Best positive and negative likelihood ratios were obtained by IgG2. The test having the greatest, statistically significant, area under the receiver operating characteristics curve was IgG2 enzyme-linked immunosorbent assay (ELISA). Thus, according to the gold standard used, IFAT and qPCR are far from fulfilling the requirements to be considered gold standards, and the test showing the highest potential to detect Leishmania infection is Leishmania-specific ELISA IgG2. PMID:20134001

Basic electrochemical properties of sputtered gold film electrodes

International Nuclear Information System (INIS)

Libansky, Milan; Zima, Jiri; Barek, Jiri; Reznickova, Alena; Svorcik, Vaclav; Dejmkova, Hana

2017-01-01

Gold nanolayers made by sputtering of pure gold (physical vapour deposition) are commonly used for many biophysical and material applications. However, the use of sputtering method for fabrication of working electrodes for electroanalytical purposes is less common. This paper focuses on the testing and characterization of sputtered working roughened gold nanostructured film electrodes, which fall into category of upcoming desirable new generation of nanostructured gold working electrodes. Gold nanostructured films (80 nm thin) were sputtered onto 50 μm thin PTFE substrates with three different types of treatment: pristine, plasma treated, and plasma treated and subsequently spontaneously grafted with biphenyl-4,4′-dithiol. The characterization of gold nanostructured film electrodes was carried out by examination of the electrode reaction of standard redox probes (ferrocyanide/ferricyanide, hydroquinone/benzoquinone) in different types of supporting electrolytes (BR buffers of various pH, KCl, KNO 3 , H 2 SO 4 ), by exploration of the electrode surface by scanning electron microscopy, by atomic force microscopy accompanied by elementary analysis and contact angle measurements. The testing of electrodes was complemented by an attempt to calculate their real surface areas from Randles-Sevcik equation. All results were compared to conventional bulk gold electrode. The practical applicability of the nanostructured gold electrodes as sensors for the determination of environmental pollutants was verified by voltammetric determination of hydroquinone as a model electrochemically oxidisable organic environmental pollutant.

Electronic structure of the gold/Bi2Sr2CaCu2O8 and gold/EuBa2Cu3O7-δ interfaces as studied by photoemission spectroscopy

International Nuclear Information System (INIS)

Dessau, D.S.; Shen, Z.; Wells, B.O.; Spicer, W.E.; List, R.S.; Arko, A.J.; Bartlett, R.J.; Fisk, Z.; Cheong, S.; Mitzi, D.B.; Kapitulnik, A.; Schirber, J.E.

1990-01-01

High-resolution photoemission has been used to probe the electronic structure of the gold/Bi 2 Sr 2 CaCu 2 O 8 and gold/EuBa 2 Cu 3 O 7-δ interface formed by a low-temperature (20 K) gold evaporation on cleaved high quality single crystals. We find that the metallicity of the EuBa 2 Cu 3 O 7-δ substrate in the near surface region (∼5 A) is essentially destroyed by the gold deposition, while the near surface region of Bi 2 Sr 2 CaCu 2 O 8 remains metallic. This has potentially wide ranging consequences for the applicability of the different types of superconductors in real devices

75 FR 14103 - Version One Regional Reliability Standard for Resource and Demand Balancing

Science.gov (United States)

2010-03-24

... current regional Reliability Standard was developed and used under a manual interchange transaction...] Version One Regional Reliability Standard for Resource and Demand Balancing March 18, 2010. AGENCY... section 215 of the Federal Power Act, the Commission proposes to remand a revised regional Reliability...

Changing organizational culture: using the CEO cancer gold standard policy initiatives to promote health and wellness at a school of public health.

Science.gov (United States)

Towne, Samuel D; Anderson, Kelsey E; Smith, Matthew Lee; Dahlke, Deborah Vollmer; Kellstedt, Debra; Purcell, Ninfa Pena; Ory, Marcia G

2015-09-03

Worksite wellness initiatives for health promotion and health education have demonstrated effectiveness in improving employee health and wellness. We examined the effects of a multifaceted health promotion campaign on organizational capacity to meet requirements to become CEO Cancer Gold Standard Accredited. We conducted an online survey to assess perceived organizational values and support for the five CEO Cancer Gold Standard Pillars for cancer prevention: tobacco cessation; physical activity; nutrition; cancer screening and early detection; and accessing information on cancer clinical trials. Baseline and follow-up surveys were sent 6-months apart to faculty, staff, and students at a school of public health to test the impact of a multifaceted health promotion campaign on perceived organizational change. Descriptive analyses were used to characterize percent improvement. Multivariate logistic regression analyses were used to control for participants' university status. The current organizational culture highly supported tobacco cessation at both time points. Significant improvements (p screening, and early detection of cancer' and 'accessing cancer treatment and clinical trials'. Health promotion and education efforts using multiple approaches were effective to improve perceived organizational values and support for cancer prevention and early detection, and increase access to information about cancer clinical trials. Future studies are needed to examine broader impacts of implementing worksite health promotion initiatives.

Chromaticity and Glossiness of Gold, Silver, and Bronze Colors

Directory of Open Access Journals (Sweden)

Tomohisa Matsumoto

2011-05-01

Full Text Available Appearance of metallic colors, such as gold, silver and bronze, depends on chromaticity and glossiness of a surface. We aim to obtain the chromaticity region of gold, silver, and bronze by using CG simulated surfaces with various glossiness. The physical glossiness was defined by the intensity ratio of specular reflectance of the surface stimulus. The observer estimated degree of perceived glossiness, and also degree of gold, silver, or bronze appearance of the stimulus with a physical glossiness and a chromaticity. The results showed that the stimulus began to appear gold, silver or bronze at a certain chromaticity point only when the stimulus had glossiness. The chromaticity range, where gold, silver and bronze colors were observed, expanded as the degree of glossiness increased. Furthermore the ratio of the degree of gold, silver or bronze colors to that of glossiness of the stimulus was found to be different among the chromaticity points of the stimulus. This ratio was highest with highly saturated stimuli for gold and bronze colors, and with achromatic stimuli for silver color.

Radiochemical neutron activation analysis of gold in geochemical samples

International Nuclear Information System (INIS)

Zilliacus, R.

1983-01-01

A fast method for the radiochemical neutron activation analysis of gold in geochemical samples is described. The method is intended for samples having background concentrations of gold. The method is based on the dissolution of samples with hydrofluoric acid and aqua regia followed by the dissolution of the fluorides with boric acid and hydrochloric acid. Gold is then adsorbed on activated carbon by filtrating the solution through a thin carbon layer. The activity measurements are carried out using a Ge(Li)-detector and a multichannel analyzer. The chemical yields of the separation determined by reirradiation vary between 60 and 90%. The detection limit of the method is 0.2 ng/g gold in rock samples. USGS standard rocks and exploration reference materials are analyzed and the results are presented and compared with literature data. (author)

Argument for a non-standard broad-line region

International Nuclear Information System (INIS)

Collin, S.

1987-01-01

The region emitting the broad lines (BLR) in quasars and AGN has a ''Standard Status''. It is shown that this status raises strong problems concerning the energetic budget and the thermal state of the BLR. A possible solution is proposed [fr

Terminalia chebula mediated green and rapid synthesis of gold nanoparticles

Science.gov (United States)

Mohan Kumar, Kesarla; Mandal, Badal Kumar; Sinha, Madhulika; Krishnakumar, Varadhan

2012-02-01

Biologically inspired experimental process in synthesising nanoparticles is of great interest in present scenario. Biosynthesis of nanoparticles is considered to be one of the best green techniques in synthesising metal nanoparticles. Here, an in situ green biogenic synthesis of gold nanoparticles using aqueous extracts of Terminalia chebula as reducing and stabilizing agent is reported. Gold nanoparticles were confirmed by surface plasmon resonance in the range of 535 nm using UV-visible spectrometry. TEM analysis revealed that the morphology of the particles thus formed contains anisotropic gold nanoparticles with size ranging from 6 to 60 nm. Hydrolysable tannins present in the extract of T. chebula are responsible for reductions and stabilization of gold nanoparticles. Antimicrobial activity of gold nanoparticles showed better activity towards gram positive S. aureus compared to gram negative E. coli using standard well diffusion method.

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.

Antifungal activity of gold nanoparticles prepared by solvothermal method

International Nuclear Information System (INIS)

Ahmad, Tokeer; Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna; Manzoor, Nikhat; Ahmad, Aijaz; Ahmed, Jahangeer; Al-Shihri, Ayed S.

2013-01-01

Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m 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 2/ g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl 2 and NaBH 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 2 , however, NaBH 4 produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m 2 /g for 7 nm and 269 m 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 + efflux of the Candida species than 15 nm sized gold nanoparticles.

Biometry and intraocular lens power calculation results with a new optical biometry device: comparison with the gold standard.

Science.gov (United States)

Kaswin, Godefroy; Rousseau, Antoine; Mgarrech, Mohamed; Barreau, Emmanuel; Labetoulle, Marc

2014-04-01

To evaluate the agreement in axial length (AL), keratometry (K), anterior chamber depth (ACD) measurements; intraocular lens (IOL) power calculations; and predictability using a new partial coherence interferometry (PCI) optical biometer (AL-Scan) and a reference (gold standard) PCI optical biometer (IOLMaster 500). Service d'Ophtalmologie, Hopital Bicêtre, APHP Université, Paris, France. Evaluation of a diagnostic device. One eye of consecutive patients scheduled for cataract surgery was measured. Biometry was performed with the new biometer and the reference biometer. Comparisons were performed for AL, average K at 2.4 mm, ACD, IOL power calculations with the Haigis and SRK/T formulas, and postoperative predictability of the devices. A P value less than 0.05 was statistically significant. The study enrolled 50 patients (mean age 72.6 years±4.2 SEM). There was a good correlation between biometers for AL, K, and ACD measurements (r=0.999, r=0.933, and r=0.701, respectively) and between IOL power calculation with the Haigis formula (r=0.972) and the SRK/T formula (r=0.981). The mean absolute error (MAE) in IOL power prediction was 0.42±0.08 diopter (D) with the new biometer and 0.44±0.08 D with the reference biometer. The MAE was 0.20 D with the Haigis formula and 0.19 with the SRK/T formula (P=.36). The new PCI biometer provided valid measurements compared with the current gold standard, indicating that the new device can be used for IOL power calculations for routine cataract surgery. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Ion induced segregation in gold nanostructured thin films on silicon

International Nuclear Information System (INIS)

Ghatak, J.; Satyam, P.V.

2008-01-01

We report a direct observation of segregation of gold atoms to the near surface regime due to 1.5 MeV Au 2+ ion impact on isolated gold nanostructures deposited on silicon. Irradiation at fluences of 6 x 10 13 , 1 x 10 14 and 5 x 10 14 ions cm -2 at a high beam flux of 6.3 x 10 12 ions cm -2 s -1 show a maximum transported distance of gold atoms into the silicon substrate to be 60, 45 and 23 nm, respectively. At a lower fluence (6 x 10 13 ions cm -2 ) transport has been found to be associated with the formation of gold silicide (Au 5 Si 2 ). At a high fluence value of 5 x 10 14 ions cm -2 , disassociation of gold silicide and out-diffusion lead to the segregation of gold to defect - rich surface and interface regions.

Differential uptake of gold nanoparticles by 2 species of tadpole, the wood frog (Lithobates sylvaticus) and the bullfrog (Lithobates catesbeianus).

Science.gov (United States)

Thompson, Lucas B; Carfagno, Gerardo L F; Andresen, Kurt; Sitton, Andrea J; Bury, Taylor; Lee, Laura L; Lerner, Kevin T; Fong, Peter P

2017-12-01

Engineered nanoparticles are aquatic contaminants of emerging concern that exert ecotoxicological effects on a wide variety of organisms. We exposed cetyltrimethylammonium bromide-capped spherical gold nanoparticles to wood frog and bullfrog tadpoles with conspecifics and in combination with the other species continuously for 21 d, then measured uptake and localization of gold. Wood frog tadpoles alone and in combination with bullfrog tadpoles took up significantly more gold than bullfrogs. Bullfrog tadpoles in combination with wood frogs took up significantly more gold than controls. The rank order of weight-normalized gold uptake was wood frogs in combination > wood frogs alone > bullfrogs in combination > bullfrogs alone > controls. In all gold-exposed groups of tadpoles, gold was concentrated in the anterior region compared with the posterior region of the body. The concentration of gold nanoparticles in the anterior region of wood frogs both alone and in combination with bullfrogs was significantly higher than the corresponding posterior regions. We also measured depuration time of gold in wood frogs. After 21 d in a solution of gold nanoparticles, tadpoles lost >83% of internalized gold when placed in gold-free water for 5 d. After 10 d in gold-free water, tadpoles lost 94% of their gold. After 15 d, gold concentrations were below the level of detection. Our finding of differential uptake between closely related species living in similar habitats with overlapping geographical distributions argues against generalizing toxicological effects of nanoparticles for a large group of organisms based on measurements in only one species. Environ Toxicol Chem 2017;36:3351-3358. © 2017 SETAC. © 2017 SETAC.

Decision Making in the Management of Extracapsular Fractures of the Proximal Femur – is the Dynamic Hip Screw the Prevailing Gold Standard?

Science.gov (United States)

Jacob, Joshua; Desai, Ankit; Trompeter, Alex

2017-01-01

Currently, approximately half of all hip fractures are extracapsular, with an incidence as high as 50 in 100,000 in some countries. The common classification systems fail to explain the logistics of fracture classification and whether they all behave in the same manner. The Muller AO classification system is a useful platform to delineate stable and unstable fractures. The Dynamic hip screw (DHS) however, has remained the ‘gold standard’ implant of choice for application in all extracapsular fractures. The DHS relies on the integrity and strength of the lateral femoral wall as well as the postero-medial fragment. An analysis of several studies indicates significant improvements in design and techniques to ensure a better outcome with intramedullary nails. This article reviews the historical trends that helped to evolve the DHS implant as well as discussing if the surgeon should remain content with this implant. We suggest that the gold standard surgical management of extracapsular fractures can, and should, evolve. PMID:29290858

Light-activated microbubbles around gold nanorods for photoacoustic microsurgery

Science.gov (United States)

Cavigli, Lucia; Centi, Sonia; Lai, Sarah; Borri, Claudia; Micheletti, Filippo; Tortoli, Paolo; Panettieri, Ilaria; Streit, Ingolf; Rossi, Francesca; Ratto, Fulvio; Pini, Roberto

2018-02-01

The increasing interest around imaging and microsurgery techniques based on the photoacoustic effect has boosted active research into the development of exogenous contrast agents that may enhance the potential of this innovative approach. In this context, plasmonic particles as gold nanorods are achieving resounding interest, owing to their efficiency of photothermal conversion, intense optical absorbance in the near infrared region, inertness in the body and convenience for conjugation with ligands of molecular targets. On the other hand, the photoinstability of plasmonic particles remains a remarkable obstacle. In particular, gold nanorods easily reshape into nanospheres and so lose their optical absorbance in the near infrared region, under exposure to few-ns-long laser pulses. This issue is attracting much attention and stimulating ad-hoc solutions, such as the addition of rigid shells and the optimization of multiple parameters. In this contribution, we focus on the influence of the shape of gold nanorods on their photothermal behavior and photostability. We describe the photothermal process in the gold nanorods by modeling their optical absorption and consequent temperature dynamics as a function of their aspect ratio (length / diameter). Our results suggest that increasing the aspect ratio does probably not limit the photostability of gold nanorods, while shifting the plasmonic peak towards wavelengths around 1100 nm, which hold more technological interest.

Coal-gold agglomeration: an alternative separation process in gold recovery

Energy Technology Data Exchange (ETDEWEB)

Akcil, A.; Wu, X.Q.; Aksay, E.K. [Suleyman Demirel University, Isparta (Turkey). Dept. of Mining Engineering

2009-07-01

Considering the increasing environmental concerns and the potential for small gold deposits to be exploited in the future, the uses of environmentally friendly processes are essential. Recent developments point to the potential for greatly increased plant performance through a separation process that combines the cyanide and flotation processes. In addition, this kind of alternative treatment processes to the traditional gold recovery processes may reduce the environmental risks of present small-scale gold mining. Gold recovery processes that applied to different types of gold bearing ore deposits show that the type of deposits plays an important role for the selection of mineral processing technologies in the production of gold and other precious metals. In the last 25 years, different alternative processes have been investigated on gold deposits located in areas where environmental issues are a great concern. In 1988, gold particles were first recovered by successful pilot trial of coal-gold agglomeration (CGA) process in Australia. The current paper reviews the importance of CGA in the production of gold ore and identifies areas for further development work.

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.

Linear and Nonlinear Optical Properties of Micrometer-Scale Gold Nanoplates

International Nuclear Information System (INIS)

Liu Xiao-Lan; Peng Xiao-Niu; Yang Zhong-Jian; Li Min; Zhou Li

2011-01-01

Micrometer-scale gold nanoplates have been synthesized in high yield through a polyol process. The morphology, crystal structure and linear optical extinction of the gold nanoplates have been characterized. These gold nanoplates are single-crystalline with triangular, truncated triangular and hexagonal shapes, exhibiting strong surface plasmon resonance (SPR) extinction in the visible and near-infrared (NIR) region. The linear optical properties of gold nanoplates are also investigated by theoretical calculations. We further investigate the nonlinear optical properties of the gold nanoplates in solution by Z-scan technique. The nonlinear absorption (NLA) coefficient and nonlinear refraction (NLR) index are measured to be 1.18×10 2 cm/GW and −1.04×10 −3 cm 2 /GW, respectively. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Silver and gold in the Protein Data Bank.

Science.gov (United States)

Carugo, Oliviero

2017-10-01

The structural features of the silver and gold sites in protein crystal structures extracted from the Protein Data Bank have been investigated. It is observed that both cations have nearly always low oxidations states (+1) and low coordination numbers, adopt standard stereochemistries, and interact preferentially (particularly gold) with sulfur donor atoms of cysteine and methionine side-chains. Interestingly, gold cation have been very often refined with occupancy minor than 1.0 and are very often "naked", in the sense that no donor atoms are sufficiently close to the metal cation. This apparently strange observation points out towards the need to develop specific and efficient validation tools for these elements when they are coordinated to proteins. Copyright © 2017 Elsevier Inc. All rights reserved.

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... EXCHANGE OF PAPER CURRENCY AND COIN In General § 100.4 Gold coin and gold certificates in general. Gold coins, and gold certificates of the type issued before January 30, 1934, are exchangeable, as provided...

Real-time cardiac magnetic resonance cine imaging with sparse sampling and iterative reconstruction for left-ventricular measures: Comparison with gold-standard segmented steady-state free precession.

Science.gov (United States)

Camargo, Gabriel C; Erthal, Fernanda; Sabioni, Leticia; Penna, Filipe; Strecker, Ralph; Schmidt, Michaela; Zenge, Michael O; Lima, Ronaldo de S L; Gottlieb, Ilan

2017-05-01

Segmented cine imaging with a steady-state free-precession sequence (Cine-SSFP) is currently the gold standard technique for measuring ventricular volumes and mass, but due to multi breath-hold (BH) requirements, it is prone to misalignment of consecutive slices, time consuming and dependent on respiratory capacity. Real-time cine avoids those limitations, but poor spatial and temporal resolution of conventional sequences has prevented its routine application. We sought to examine the accuracy and feasibility of a newly developed real-time sequence with aggressive under-sampling of k-space using sparse sampling and iterative reconstruction (Cine-RT). Stacks of short-axis cines were acquired covering both ventricles in a 1.5T system using gold standard Cine-SSFP and Cine-RT. Acquisition parameters for Cine-SSFP were: acquisition matrix of 224×196, temporal resolution of 39ms, retrospective gating, with an average of 8 heartbeats per slice and 1-2 slices/BH. For Cine-RT: acquisition matrix of 224×196, sparse sampling net acceleration factor of 11.3, temporal resolution of 41ms, prospective gating, real-time acquisition of 1 heart-beat/slice and all slices in one BH. LV contours were drawn at end diastole and systole to derive LV volumes and mass. Forty-one consecutive patients (15 male; 41±17years) in sinus rhythm were successfully included. All images from Cine-SSFP and Cine-RT were considered to have excellent quality. Cine-RT-derived LV volumes and mass were slightly underestimated but strongly correlated with gold standard Cine-SSFP. Inter- and intra-observer analysis presented similar results between both sequences. Cine-RT featuring sparse sampling and iterative reconstruction can achieve spatial and temporal resolution equivalent to Cine-SSFP, providing excellent image quality, with similar precision measurements and highly correlated and only slightly underestimated volume and mass values. Copyright © 2017 Elsevier Inc. All rights reserved.

Dissolution ad uptake of cadmium from dental gold solder alloy implants

International Nuclear Information System (INIS)

Bergman, B.; Bergman, M.; Soeremark, R.

1977-01-01

Pure metallic cadmium was irradiated by means of thermal neutrons. The irradiated cadmium ( 115 Cd) was placed in bags of gold foil and the bags were implanted subcutaneously in the neck region of mice. Two and 3 d respectively after implantation the mice were killed, the bags removed and the animals subjected to whole-body autoradiography. The autoradiograms revealed an uptake of 115 Cd in liver and kidney. In another experiment specimens of a cadmium-containing dental gold solder alloy, a cadmium-free dental casting gold alloy and soldered assemblies made of these two alloys were implanted subcutaneously in the neck region of mice. The animals were killed after 6 months; cadmium analysis showed significant increases in the cadmium concentration in liver and kidney of those mice which had been given implants of gold solder alloy. The study clearly shows that due to electrochemical corrosion cadmium can be released from implants and accumulated in the kidneys and the liver. (author)

Dissolution and uptake of cadmium from dental gold solder alloy implants

Energy Technology Data Exchange (ETDEWEB)

Bergman, B; Bergman, M; Soeremark, R [Umeaa Univ. (Sweden); Karolinska Institutet, Stockholm (Sweden))

1977-01-01

Pure metallic cadmium was irradiated by means of thermal neutrons. The irradiated cadmium (/sup 115/Cd) was placed in bags of gold foil and the bags were implanted subcutaneously in the neck region of mice. Two and 3 d respectively after implantation the mice were killed, the bags removed and the animals subjected to whole-body autoradiography. The autoradiograms revealed an uptake of /sup 115/Cd in liver and kidney. In another experiment specimens of a cadmium-containing dental gold solder alloy, a cadmium-free dental casting gold alloy and soldered assemblies made of these two alloys were implanted subcutaneously in the neck region of mice. The animals were killed after 6 months; cadmium analysis showed significant increases in the cadmium concentration in liver and kidney of those mice which had been given implants of gold solder alloy. The study clearly shows that due to electrochemical corrosion cadmium can be released from implants and accumulated in the kidneys and the liver.

Open Partial Nephrectomy in Renal Cancer: A Feasible Gold Standard Technique in All Hospitals

Directory of Open Access Journals (Sweden)

J. M. Cozar

2008-01-01

Full Text Available Introduction. Partial nephrectomy (PN is playing an increasingly important role in localized renal cell carcinoma (RCC as a true alternative to radical nephrectomy. With the greater experience and expertise of surgical teams, it has become an alternative to radical nephrectomy in young patients when the tumor diameter is 4 cm or less in almost all hospitals since cancer-specific survival outcomes are similar to those obtained with radical nephrectomy. Materials and Methods. The authors comment on their own experience and review the literature, reporting current indications and outcomes including complications. The surgical technique of open partial nephrectomy is outlined. Conclusions. Nowadays, open PN is the gold standard technique to treat small renal masses, and all nonablative techniques must pass the test of time to be compared to PN. It is not ethical for patients to undergo radical surgery just because the urologists involved do not have adequate experience with PN. Patients should be involved in the final treatment decision and, when appropriate, referred to specialized centers with experience in open or laparoscopic partial nephrectomies.

Performances of Four Helicobacter pylori Serological Detection Kits Using Stool Antigen Test as Gold Standard.

Science.gov (United States)

Biranjia-Hurdoyal, Susheela D; Seetulsingh-Goorah, Sharmila P

2016-01-01

The aim was to determine the performances of four Helicobacter pylori serological detection kits in different target groups, using Amplified IDEIA™ Hp StAR™ as gold standard. Kits studied were Rapid Immunochromatoghraphic Hexagon, Helicoblot 2.1, an EIA IgG kit and EIA IgA kit. Stool and blood samples were collected from 162 apparently healthy participants (control) and 60 Type 2 diabetes mellitus (T2DM) patients. The performances of the four serological detection kits were found to be affected by gender, age, health status and ethnicity of the participants. In the control group, the Helicoblot 2.1 kit had the best performance (AUC = 0.85; ppoor performances. In the T2DM subgroup, the kits H2.1 and EIA IgG had best performances, with accuracies of 96.5% and 93.1% respectively. The performance of EIA IgG improved with adjustment of its cut-off value. The performances of the detection kits were affected by various factors which should be taken into consideration.

Could Serum Laminin Replace Liver Biopsy as Gold Standard for Predicting Significant Fibrosis in Patients with Chronic Hepatitis B? Clinical and Histopathological Study

OpenAIRE

Abeer M. Hafez; Yasser S. Sheta; Mohamed H. Ibrahim; Shereen A. Elshazly

2013-01-01

Background: The prognosis and clinical treatment of chronic liver disease depends greatly on the progression of liver fibrosis, which has resulted from the loss of normal liver cell function due to disorganized over-accumulation of extra-cellular matrix (ECM) components in the liver. Liver biopsy has been considered the gold standard for staging and grading hepatic fibrosis and inflammation. However, the procedure is associated with complications such as bleeding, infection, damage to liver t...

Modification of high density polyethylene by gold implantation using different ion energies

Energy Technology Data Exchange (ETDEWEB)

Nenadović, M.; Potočnik, J. [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12–14, 11001 Belgrade (Serbia); Mitrić, M. [INS Vinca, Condensed Matter Physics Laboratory, University of Belgrade, Mike Alasa 12–14, 11001 Belgrade (Serbia); Štrbac, S. [ICTM Institute of Electrochemistry, University of Belgrade, Njegoseva 12, 11001 Belgrade (Serbia); Rakočević, Z., E-mail: zlatkora@vinca.rs [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12–14, 11001 Belgrade (Serbia)

2013-11-01

High density polyethylene (HDPE) samples were modified by Au{sup +} ion implantation at a dose of 5 × 10{sup 15} ions cm{sup −2}, using energies of 50, 100, 150 and 200 keV. The existence of implanted gold in the near-surface region of HDPE samples was confirmed by X-ray diffraction analysis. Surface roughness and Power Spectral Density analyses based on Atomic Force Microscopy (AFM) images of the surface topography revealed that the mechanism of HDPE modification during gold ion implantation depended on the energy of gold ions. Histograms obtained from phase AFM images indicated a qualitative change in the chemical composition of the surface during implantation with gold ions with different energies. Depth profiles obtained experimentally from cross-sectional Force Modulation Microscopy images and ones obtained from a theoretical simulation are in agreement for gold ions energies lower than 100 keV. The deviation that was observed for higher energies of the gold ions is explained by carbon precipitation in the near surface region of the HDPE, which prevented the penetration of gold ions further into the depth of the sample. - Highlights: • HDPE was implanted by Au{sup +} ions using energies of 50, 100, 150 and 200 keV. • Surface composition was analyzed from phase AFM images. • FMM depth profiles are in agreement with theoretical ones for energies up to 100 keV. • A deviation is observed for higher gold ion energies.

Modification of high density polyethylene by gold implantation using different ion energies

International Nuclear Information System (INIS)

Nenadović, M.; Potočnik, J.; Mitrić, M.; Štrbac, S.; Rakočević, Z.

2013-01-01

High density polyethylene (HDPE) samples were modified by Au + ion implantation at a dose of 5 × 10 15 ions cm −2 , using energies of 50, 100, 150 and 200 keV. The existence of implanted gold in the near-surface region of HDPE samples was confirmed by X-ray diffraction analysis. Surface roughness and Power Spectral Density analyses based on Atomic Force Microscopy (AFM) images of the surface topography revealed that the mechanism of HDPE modification during gold ion implantation depended on the energy of gold ions. Histograms obtained from phase AFM images indicated a qualitative change in the chemical composition of the surface during implantation with gold ions with different energies. Depth profiles obtained experimentally from cross-sectional Force Modulation Microscopy images and ones obtained from a theoretical simulation are in agreement for gold ions energies lower than 100 keV. The deviation that was observed for higher energies of the gold ions is explained by carbon precipitation in the near surface region of the HDPE, which prevented the penetration of gold ions further into the depth of the sample. - Highlights: • HDPE was implanted by Au + ions using energies of 50, 100, 150 and 200 keV. • Surface composition was analyzed from phase AFM images. • FMM depth profiles are in agreement with theoretical ones for energies up to 100 keV. • A deviation is observed for higher gold ion energies

Artisanal and Small-Scale Gold Mining Without Mercury

Science.gov (United States)

Mercury-free techniques are safer for miners, their families and local communities. They can also help miners qualify for certification under fair-mined standards, potentially allowing them to market their gold at higher prices.

Using ASD data to identify the altered minerals for exploring of gold deposit in the Beishan area, North China

Science.gov (United States)

Ren, G. L.; Yi, H.; Yang, M.; Liang, N.; Li, J. Q.; Yang, J. L.

2016-11-01

Hyperspectral information of altered minerals plays an important role in the identifications of mineralized zones. In this study, the altered minerals of two gold deposits from Fangshankou-Laojinchang regions of Beishan metallogenic belt were measured by ASD field Spectrometer. Many gold deposits would have a close relationship with Variscan magma intrusion, which have been found in study region. The alteration minerals have been divided six types by the spectral results, i.e. sericite, limonite, dolomite, chlorite, epidote and calcite. The distribution characteristics and formations of altered minerals were discussed here. By the ASD, the spectral curve of different geological units in the Jintanzi and Fangshankou gold deposits were analysed and summarized. The results show that the sericite and limonite are mainly related with the gold mineralization and widely occurred in the gold deposits. Therefore, we proposed that the sericite and limonite are the iconic alteration mineral assemblages for gold mineralization and the models of altered minerals for gold deposits could be established in this region.

Jabiluka gold-uranium project

International Nuclear Information System (INIS)

1988-01-01

The Jabiluka gold-uranium deposit, 230km east of Darwin in the Alligator Rivers Region of the Northern Territory, was discovered by Pancontinental Mining Limited in 1971. Jabiluka, with reserves in excess of 200,000 tonnes of contained U 3 O 8 in two deposits 500 metres apart, is the world's largest high grade uranium deposit and also contains nearly 12 tonnes of gold. It is proposed that only the larger deposit, Jabiluka II will be mined - by underground extraction methods, and that 275,000 tonnes of ore per year will be mined and processed to produce 1,500 tonnes of U 3 O 8 and up to 30,000 oz of gold. The revenue from the uranium sales is estimated to be of the order of A$100 million per year at A$30/lb. By the end of 1982 all necessary mining and environmental approvals had been obtained and significant marketing progress made. With the Australian Labor Party winning Commonwealth Government in the 1983 election, Pancontinental's permission to seek sales contracts was withdrawn and development of the Jabiluka deposit ceased. Jabiluka remains undeveloped - awaiting a change in Australian Government policy on uranium. figs., maps

Lithogeochemistry of Carlin-type gold mineralization in the Gold Bar district, Battle Mountain-Eureka trend, Nevada

Science.gov (United States)

Yigit, O.; Hofstra, A.H.

2003-01-01

The Gold Bar district contains five Carlin-type gold deposits and four resources for a combined gold endowment of 1.6 M oz [50 t]. The gold deposits are hosted in Devonian carbonate rocks below parautochthonous and allochthonous Paleozoic siliciclastic rocks emplaced during the Early Mississippian Antler orogeny. The district is in the Battle Mountain-Eureka trend, a long-lived structural feature that localized intrusions and ore deposits of different types and ages. The whole-rock geochemistry of four different mineralized and unmineralized Devonian carbonate rock units (two favorable and two unfavorable) were determined and interpreted in the context of the regional geology. A combination of basic statistics, R-mode factor analysis, isocon plots, and alteration diagrams were utilized to (1) identify favorable geochemical attributes of the host rocks, (2) characterize alteration and associated element enrichments and depletions, and (3) identify the mechanism of gold precipitation. This approach also led to the recognition of other types of alteration and mineralization in host rocks previously thought to be solely affected by Carlin-type mineralization. Unit 2 of the Upper Member of the Denay Formation, with the highest Al2O3, Fe2O3 and SiO2 contents and the lowest CaO content, is the most favorable host rock. Based on the high regression coefficients of data arrays on X-Y plots that project toward the origin, Al2O3 and TiO2 were immobile and K2O and Fe2O3 were relatively immobile during alteration and mineralization. Specific element associations identified by factor analysis are also prominent on isocon diagrams that compare the composition of fresh and altered equivalents of the same rock units. The most prominent associations are: Au, As, Sb, SiO2, TI, -CaO and -LOI, the main gold mineralizing event and related silicification and decalcification; Cd, Zn, Ag, P, Ni and Tl, an early base metal event; and MgO, early dolomitization. Alteration diagrams

Application of the Fundamental Parameter Method for X-ray fluorescence analysis of gold jewellery alloys

International Nuclear Information System (INIS)

Le Hong Khiem

2004-01-01

The Fundamental Parameter Method has been used for the correction of the matrix effects for determination of the fineness of gold in the ternary Au-Ag-Cu yellow jewellery alloys. A computer code GOLDANA based on this algorithm has been developed for both data taking and on-line determining the fineness of gold jewellery. Only one ternary Au-Ag-Cu standard sample is required. The analysis performance has been tested by measurements conducted on certified gold reference materials, with the use of the fundamental method, could be used for quickly determining the gold concentration in gold jewellery alloys with an acceptable accuracy for the gold jewellery producers. (author)

Gold Nanoparticles Obtained by Bio-precipitation from Gold(III) Solutions

International Nuclear Information System (INIS)

Gardea-Torresdey, J.L.; Tiemann, K.J.; Gamez, G.; Dokken, K.; Tehuacanero, S.; Jose-Yacaman, M.

1999-01-01

The use of metal nanoparticles has shown to be very important in recent industrial applications. Currently gold nanoparticles are being produced by physical methods such as evaporation. Biological processes may be an alternative to physical methods for the production of gold nanoparticles. Alfalfa biomass has shown to be effective at passively binding and reducing gold from solutions containing gold(III) ions and resulting in the formation of gold(0) nanoparticles. High resolution microscopy has shown that five different types of gold particles are present after reaction with gold(III) ions with alfalfa biomass. These particles include: fcc tetrahedral, hexagonal platelet, icosahedral multiple twinned, decahedral multiple twinned, and irregular shaped particles. Further analysis on the frequency of distribution has shown that icosahedral and irregular particles are more frequently formed. In addition, the larger particles observed may be formed through the coalescence of smaller particles. Through modification of the chemical parameters, more uniform particle size distribution may be obtained by the alfalfa bio-reduction of gold(III) from solution

Neutron activation for logging the distribution of gold in bore-hole cores

International Nuclear Information System (INIS)

Rahmanian, H.; Watterson, J.I.W.

1992-01-01

A new method for the non-destructive determination of gold in bore-hole cores has been developed using instrumental neutron activation analysis with a 252 Cf source. The procedure obtains the distribution and concentration of gold along the longitudinal axis of the core i.e. a log of the gold concentration. The accuracy of the method is comparable to fire assay at a level of 2 ppm and has a detection limit of 1 ppm under the conditions used. The assay of the gold is carried out by employing a novel variation of the conventional comparator method using gold wires as both standard and flux monitor. A method is described for logging gold in bore-hole cores using neutron activation with a 160 μg 252 Cf neutron source. The method has a limit of detection of about 1 ppm under the described conditions. (author)

Size fraction assaying of gold bearing rocks (for gold extraction) by ...

African Journals Online (AJOL)

A novel method has been developed for processing and extraction of gold from gold bearing rocks for use by small-scale gold miners in Ghana. The methodology involved crushing of gold bearing hard rocks to fine particles to form a composite sample and screening at a range of sizes. Gold distribution in the composite ...

Determination of radon-222 emissions to the environment from gold underground mines of Nova Lima region - MG, Brazil

International Nuclear Information System (INIS)

Binns, D.A.C.; Gouvea, V.A.; Melo, V.P.; Tolentino, J.

1996-01-01

Measurements of Rd-222 concentrations were performed at some points into drift of three gold underground mining companies of Nova Lima region - MG/Br. In the two oldest mines, Mina Grande and Mina Cuiaba, were found the highest concentrations, with a mean of 1911 Bq.m -3 , while a mean of concentration into the other mine, Mina Raposo, was 108 Bq.m -3 . The Mina Raposo correspond to a modern facility with efficient exhaust and ventilation system. The results of this study have demonstrated that ventilation is the most important factor to reduce the occupational radiation exposure of workers in mining operations

Geostatistical Approach to Estimating the Gold Ore Characteristics and Gold Reserves: A Case Study Daksa Area, Quang Nam Province, Viet Nam

Science.gov (United States)

Luan Truong, Xuan; Luong Le, Van; Quang Truong, Xuan

2015-04-01

Daksa gold deposit is the biggest gold deposits in Vietnam. The Daksa geological structure complicated, distributed mainly metamorphosed sedimentary NuiVu formation (PR3-?1nv2). The sulfide gold ore bodies distributed in quartz schist, quartz - biotite related to faut and distribution wing anticline. The gold ore bodies form circuits, network circuits, circuits lenses; fill the cup surface layer of the developing northeast - southwest; is the less than or west longitude north - SE. The results show that, Au and accompanying elements (Ag, Pb and Zn) have correlated pretty closely. All of its consistent with the logarithmic distribution standard, in accordance with the law of distribution of content mineral rare. The structure functions have nugget effect and spherical models with show that Au and accompanying elements special variation are changes. Au contents shown local anisotropy, no clearly anisotropy (K=1,17) and weakly anisotropy (K=1,4). Intensity mineralization of the ore bodies are quite high with demand spherical conversion coefficient ranging from 0.49 to 0.75 and from 0.66 to 0.97 (for other body). With nugget effects, ore bodies shown that it is consistent with mineralization in the ore bodies study, ore erasable, micro vein, infilling fractures in quartz vein. All of variogram presents local anisotropy, indicated gold mineralization at study area has least two-mineralization stages, consistent with the analysis of mineralography samples. By the results of the structure function study, the authors present the system optimization for exploration deposit and used to evaluate gold reserves by Ordinary Kriging. High accuracy of Kriging estimation results are expressed in the minimum Kriging variance, by compare the results calculated by some other methods (such as distance inverse weighting method, ..) and specially compare to the results of a some blocks have been exploited. Key words: Geostat and gold deposits VN. Daksa and gold mineralization. Geostat

Secondary Emission From Synthetic Opal Infiltrated by Colloidal Gold and Glycine

International Nuclear Information System (INIS)

Dovbeshko, G.I.; Fesenko, O.M.; Boyko, V.V.; Romanyuk, V.R.; Gorelik, V.S.; Moiseyenko, V.N.; Sobolev, V.B.; Shvalagin, V.V.

2012-01-01

A comparison of the secondary emission (photoluminescence) and Bragg reflection spectra of photonic crystals (PC), namely, synthetic opals, opals infiltrated by colloidal gold, glycine, and a complex of colloidal gold with glycine is performed. The infiltration of colloidal gold and a complex of colloidal gold with glycine into the pores of PC causes a short-wavelength shift (about 5-15 nm) of the Bragg reflection and increases the intensity of this band by 1.5-3 times. In photoluminescence, the infiltration of PC by colloidal gold and colloidal gold with glycine suppresses the PC emission band near 375-450 nm and enhances the shoulder of the stop-zone band of PC in the region of 470-510 nm. The shape of the observed PC emission band connected with defects in synthetic opal is determined by the type of infiltrates and the excitation wavelength. Possible mechanisms of the effects are discussed.

Self-absorption of neutron capture gamma-rays in gold samples

International Nuclear Information System (INIS)

Wisshak, K.; Walter, G.; Kaeppeler, F.

1983-06-01

The self absorption of neutron capture gamma rays in gold samples has been determined experimentally for two standard setups used in measurements of neutron capture cross sections. One makes use of an artificially collimated neutron beam and two C 6 D 6 detectors, the other of kinematically collimated neutrons and three Moxon-Rae detectors. Correction factors for an actual measurement of a neutron capture cross section using a gold standard of 1 mm thickness up to 12% were found for the first setup while they are only 4% for the second setup. The present data allow to determine the correction in an actual measurement with an accuracy of 0.5-1%. (orig.) [de

Improved Margins Detection of Regions Enriched with Gold Nanoparticles inside Biological Phantom

Directory of Open Access Journals (Sweden)

Yossef Danan

2017-02-01

Full Text Available Utilizing the surface plasmon resonance (SPR effect of gold nanoparticles (GNPs enables their use as contrast agents in a variety of biomedical applications for diagnostics and treatment. These applications use both the very strong scattering and absorption properties of the GNPs due to their SPR effects. Most imaging methods use the light-scattering properties of the GNPs. However, the illumination source is in the same wavelength of the GNPs’ scattering wavelength, leading to background noise caused by light scattering from the tissue. In this paper we present a method to improve border detection of regions enriched with GNPs aiming for the real-time application of complete tumor resection by utilizing the absorption of specially targeted GNPs using photothermal imaging. Phantoms containing different concentrations of GNPs were irradiated with a continuous-wave laser and measured with a thermal imaging camera which detected the temperature field of the irradiated phantoms. By modulating the laser illumination, and use of a simple post processing, the border location was identified at an accuracy of better than 0.5 mm even when the surrounding area got heated. This work is a continuation of our previous research.

The application study on the prospecting for gold by car-borne gamma-ray spectrometric method in northern Hebei and other areas

International Nuclear Information System (INIS)

Ma Zhongxiang; Liu Tengyao; Zhang Peng; Lu Shili; Zhai Yugui; Ma Yanfang

1995-01-01

The prospecting method for gold by car-borne gamma-ray spectrometric survey is a new geophysical and geochemical technique in the search for concealed gold deposits which can be used to effectively predict the regional gold metallogenetic potential area. The method of car-borne gamma-ray spectrometric survey was adopted and 63416 data at gamma-ray spectrometric measuring sites from rock masses (or strata) in northern Hebei and other areas (49100 km 2 ) are obtained. On the basis of the size of geological bodies, the sliding filtering technique was applied to process the gamma-ray spectrometric data from regional geological bodies and maps showing the parameter distribution characteristics were plotted (11 sheets). In accordance with the thorough on the distribution characteristics of gamma-ray spectrometric parameters that reflect the regional geological environment of gold metallogenesis, a set of gamma-ray spectrometric combination parameters in correlation with regional gold metallogenesis has been established and the characteristic information of gamma-ray spectrometric parameters has been extracted. Combined with geological information, the gold metallogenetic geological environment in the working area was studied, and two potential areas were predicted. After verification, gold mineralization was encountered in some areas. The study results show that the car-borne gamma-ray spectrometric method used for regional gold prospecting is a rapid, economical and effective one

Nanomolar Trace Metal Analysis of Copper at Gold Microband Arrays

Science.gov (United States)

Wahl, A.; Dawson, K.; Sassiat, N.; Quinn, A. J.; O'Riordan, A.

2011-08-01

This paper describes the fabrication and electrochemical characterization of gold microband electrode arrays designated as a highly sensitive sensor for trace metal detection of copper in drinking water samples. Gold microband electrodes have been routinely fabricated by standard photolithographic methods. Electrochemical characterization were conducted in 0.1 M H2SO4 and found to display characteristic gold oxide formation and reduction peaks. The advantages of gold microband electrodes as trace metal sensors over currently used methods have been investigated by employing under potential deposition anodic stripping voltammetry (UPD-ASV) in Cu2+ nanomolar concentrations. Linear correlations were observed for increasing Cu2+ concentrations from which the concentration of an unknown sample of drinking water was estimated. The results obtained for the estimation of the unknown trace copper concentration in drinking was in good agreement with expected values.

Nanomolar Trace Metal Analysis of Copper at Gold Microband Arrays

International Nuclear Information System (INIS)

Wahl, A; Dawson, K; Sassiat, N; Quinn, A J; O'Riordan, A

2011-01-01

This paper describes the fabrication and electrochemical characterization of gold microband electrode arrays designated as a highly sensitive sensor for trace metal detection of copper in drinking water samples. Gold microband electrodes have been routinely fabricated by standard photolithographic methods. Electrochemical characterization were conducted in 0.1 M H 2 SO 4 and found to display characteristic gold oxide formation and reduction peaks. The advantages of gold microband electrodes as trace metal sensors over currently used methods have been investigated by employing under potential deposition anodic stripping voltammetry (UPD-ASV) in Cu 2+ nanomolar concentrations. Linear correlations were observed for increasing Cu 2+ concentrations from which the concentration of an unknown sample of drinking water was estimated. The results obtained for the estimation of the unknown trace copper concentration in drinking was in good agreement with expected values.

Patterning of oxide-hardened gold black by photolithography and metal lift-off

Science.gov (United States)

Panjwani, Deep; Yesiltas, Mehmet; Nath, Janardan; Maukonen, D. E.; Rezadad, Imen; Smith, Evan M.; Peale, R. E.; Hirschmugl, Carol; Sedlmair, Julia; Wehlitz, Ralf; Unger, Miriam; Boreman, Glenn

2014-01-01

A method to pattern infrared-absorbing gold black by conventional photolithography and lift-off is described. A photo-resist pattern is developed on a substrate by standard photolithography. Gold black is deposited over the whole by thermal evaporation in an inert gas at ˜1 Torr. SiO2 is then deposited as a protection layer by electron beam evaporation. Lift-off proceeds by dissolving the photoresist in acetone. The resulting sub-millimeter size gold black patterns that remain on the substrate retain high infrared absorption out to ˜5 μm wavelength and exhibit good mechanical stability. This technique allows selective application of gold black coatings to the pixels of thermal infrared imaging array detectors.

Neutron activation determination of gold and palladium using extraction by organic sulfides

International Nuclear Information System (INIS)

Gil'berg, Eh.N.; Torgov, V.G.; Verevkin, G.V.; AN SSSR, Novosibirsk. Inst. Neorganicheskoj Khimii)

1978-01-01

Compared are methods of gold determination in standard rock samples of the USA National Geological Service: a) extraction by solutions of dioctylsulfide and oil sulfides from irradiated samples; b) preliminary extraction by the above solfides with the following extract radiation; c) the method of isotope dilution with substoichiometry extraction. A possibility is studied to determine palladium in the sulfide extract with gold using the NaI(Tl) thin crystal scintillators. It is established that joint palladium and gold extraction permits to determine them in many natural products simultaneously

Gold prices

OpenAIRE

Joseph G. Haubrich

1998-01-01

The price of gold commands attention because it serves as an indicator of general price stability or inflation. But gold is also a commodity, used in jewelry and by industry, so demand and supply affect its pricing and need to be considered when gold is a factor in monetary policy decisions.

Structural geology mapping using PALSAR data in the Bau gold mining district, Sarawak, Malaysia

Science.gov (United States)

Pour, Amin Beiranvand; Hashim, Mazlan

2014-08-01

The application of optical remote sensing data for geological mapping is difficult in the tropical environment. The persistent cloud coverage, dominated vegetation in the landscape and limited bedrock exposures are constraints imposed by the tropical climate. Structural geology investigations that are searching for epithermal or polymetallic vein-type ore deposits can be developed using Synthetic Aperture Radar (SAR) remote sensing data in tropical/sub-tropical regions. The Bau gold mining district in the State of Sarawak, East Malaysia, on the island of Borneo has been selected for this study. The Bau is a gold field similar to Carlin style gold deposits, but gold mineralization at Bau is much more structurally controlled. Geological analyses coupled with the Phased Array type L-band Synthetic Aperture Radar (PALSAR) remote sensing data were used to detect structural elements associated with gold mineralization. The PALSAR data were used to perform lithological-structural mapping of mineralized zones in the study area and surrounding terrain. Structural elements were detected along the SSW to NNE trend of the Tuban fault zone and Tai Parit fault that corresponds to the areas of occurrence of the gold mineralization in the Bau Limestone. Most of quartz-gold bearing veins occur in high-angle faults, fractures and joints within massive units of the Bau Limestone. The results show that four deformation events (D1-D4) in the structures of the Bau district and structurally controlled gold mineralization indicators, including faults, joints and fractures are detectable using PALSAR data at both regional and district scales. The approach used in this study can be more broadly applicable to provide preliminary information for exploration potentially interesting areas of epithermal or polymetallic vein-type mineralization using the PALSAR data in the tropical/sub-tropical regions.

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...... images and then to reappear by changing the scanning force. By combining contact mode AFM imaging and local force measurements, the interaction between the nanobubbles and the probe can be analyzed and give information about the characteristics of nanobubbles. A model of the forces between the AFM probe...

New possibilities for quantitative measurements of regional cerebral blood flow with gold-195m

International Nuclear Information System (INIS)

Lindner, P.; Nickel, O.

1985-01-01

A previously reported theory for quantitative cerebral blood flow measurement for nondiffusible radiotracers has been applied to patients after stroke and to volunteers undergoing a mental stimulation exercise. The energy spectrum of gold-195m shows two strong photon peaks, one at an energy level of 68 keV and a second at an energy-level of 262 keV. The low energy peak is suitable for perfusion studies in lateral views of the hemispheres; no look-through effect is seen. The high energy level is good for studies in posterior-anterior positions. Parametric images for quantitative regional cerebral blood flow can be generated. The area of occluded vessels in the case of stroke can be detected. Quantitative activation patterns of cerebral blood flow during mental stimulation can be generated. The results prove that, not only with freely diffusible indicators like xenon but also with nondiffusible indicators, it is possible to measure quantitatively cerebral blood flow patterns

Determination of trace gold in rocks and minerals by neutron activation analysis

International Nuclear Information System (INIS)

Zhao Yunlong; Zhou Suqing; Liang Yutang

1988-05-01

The determination of trace gold in rocks and minerals by neutron activation analysis is described. Two methods are used for pre-separating and concentrating the trace gold in geological samples. one of the methods is that the samples are dissolved in aqua regia solution; activated carbon paper pulp filter is used for pre-separating and concentrating trace gold by dynamic adsorption method; then the activated carbon containing gold was ashed at 650 ∼ 700 deg c. The other method is that the samples are dissolved in aqua regia solution; the polyurethane foam plastic filled with activated carbon is used for pre-separating and concentrating trace gold by dynamic adsorption method; then the foam plastic containing gold was ashed at 650 deg c. The gold in ashes is determinated by neutron activation analysis. The detection limit is 0.004ng/g. The accuracy of the method is examined by gold in reference standard material. The results of this method are in good agreement with the recommended value. For analysis of the trace gold by the methods of instrumental neutron activation analysis and epithermal neutron activation analysis, the interference of 411.8 keV γ-ray from 153 Sm, 152 Eu and fission products of uranium and the correction methods are discussed

Unreliability and error in the military's "gold standard" measure of sexual harassment by education and gender.

Science.gov (United States)

Murdoch, Maureen; Pryor, John B; Griffin, Joan M; Ripley, Diane Cowper; Gackstetter, Gary D; Polusny, Melissa A; Hodges, James S

2011-01-01

The Department of Defense's "gold standard" sexual harassment measure, the Sexual Harassment Core Measure (SHCore), is based on an earlier measure that was developed primarily in college women. Furthermore, the SHCore requires a reading grade level of 9.1. This may be higher than some troops' reading abilities and could generate unreliable estimates of their sexual harassment experiences. Results from 108 male and 96 female soldiers showed that the SHCore's temporal stability and alternate-forms reliability was significantly worse (a) in soldiers without college experience compared to soldiers with college experience and (b) in men compared to women. For men without college experience, almost 80% of the temporal variance in SHCore scores was attributable to error. A plain language version of the SHCore had mixed effects on temporal stability depending on education and gender. The SHCore may be particularly ill suited for evaluating population trends of sexual harassment in military men without college experience.

Singular value decomposition (SVD for extraction of gravity anomaly associated with gold mineralization in Tongshi gold field, Western Shandong Uplifted Block, Eastern China

Directory of Open Access Journals (Sweden)

B. B. Zhao

2011-02-01

Full Text Available A singular value decomposition (SVD program on MATLAB platform was effectively used to handle gravity signals for the Tongshi gold field. Firstly, the gravity signals were decomposed into different eigenimages with the help of singular value decomposition method (SVD. Secondly, the thresholds between the eigenvalues reflecting different layers of ore-controlling factors were established by multi-fractal method. Finally images reflecting different layers of ore-controlling factors were rebuilt. This yielded two layers of two-dimensional singular value images that depict regional and local ore-controlling factors, respectively.

1. The regional ore-controlling factor is a saddle valley with the gravity anomaly values varying from −55 to 51 μm s⁻² on the NW trending swell with the gravity anomaly values varying from −55 to 567 μm s⁻² on the SW side of the Mesozoic volcanic sedimentary basin with the gravity anomaly values varying from −56 to −974 μm s⁻². The saddle valley might be tectonically an extensional area where the Tongshi complex pluton and all gold deposits are located and thus this area is favorable for gold deposits.

2. The local ore-controlling factor is the Tongshi complex pluton with a negative circular gravity anomaly varying from −339 to −11 μm s⁻² and the ring contact metasomatic mineralization zone around the Tongshi complex with the positive gravity anomaly varying from 37 to 345 μm s⁻². The skarn and porphyry types of gold deposits are located within the complex pluton and the Carlin and cryptobreccia types of gold deposits are located within the contact metasomatic mineralization zone. Thus both of them are potential areas for gold deposits.

3. The Tongshi gold field exhibits a typical complexity with multi-layers of ore-controlling factors.

Gold Nanospheres Dispersed Light Responsive Epoxy Vitrimers

Directory of Open Access Journals (Sweden)

Zhenhua Wang

2018-01-01

Full Text Available Vitrimers represent a new class of smart materials. They are covalently crosslinked like thermosets, yet they can be reprocessed like thermoplastics. The underlying mechanism is the rapid exchange reactions which form new bonds while breaking the old ones. So far, heating is the most widely used stimulus to activate the exchange reaction. Compared to heating, light not only is much more convenient to achieve remote and regional control, but can also offer fast healing. Gold nanospheres are excellent photothermal agents, but they are difficult to disperse into vitrimers as they easily aggregate. In this paper, we use polydopamine to prepare gold nanospheres. The resultant polydopamine-coated gold nanospheres (GNS can be well dispersed into epoxy vitrimers, endowing epoxy vitrimers with light responsivity. The composites can be reshaped permanently and temporarily with light at different intensity. Efficient surface patterning and healing are also demonstrated.

Separation of polythionates and the gold thiosulfate complex in gold thiosulfate leach solutions by ion-interaction chromatography.

Science.gov (United States)

O'Reilly, John W; Shaw, Matthew J; Dicinoski, Greg W; Grosse, Andrew C; Miura, Yasuyuki; Haddad, Paul R

2002-07-01

A method for the separation of the polythionates (SxO6(2-), x = 3-5) in gold thiosulfate leach solutions using ion-interaction chromatography with conductivity and ultraviolet (UV) detection is described. Polythionates were eluted within 18 min using an eluent comprising an acetonitrile step gradient at 0.0 min from 15% v/v to 28% v/v, 3 mM TBAOH, and 2.5 mM sodium carbonate, operated using a Dionex NS1-5 micron column with guard. The developed method was capable of separating the gold thiosulfate complex ion in standard solutions, but quantification of this species in realistic leach solutions proved impractical due to a self-elution effect that caused the gold peak to be eluted as a broad band. Detection limits for polythionates using a 10 microL injection volume ranged between 1-6 mg L(-1) (5-23 microM) for conductivity and 0.8-13 mg L(-1) (4-68 microM) for UV detection, based on a signal-to-noise ratio of 2. Calibration was linear over the ranges 5-2000, 10-2000 and 25-2500 mg L(-1) for trithionate, tetrathionate and pentathionate, respectively. The technique was applied successfully to leach liquors containing 0.5 M ammonium thiosulfate, 2 M ammonia, 0.05 M copper sulfate and 20 % m/v gold ore.

Utilization of electrodeposition for electrothermal atomic absorption spectrometry determination of gold

International Nuclear Information System (INIS)

Konecna, Marie; Komarek, Josef

2007-01-01

Gold was determined by electrothermal atomic absorption spectrometry after electrochemical preconcentration on the graphite ridge probe used as a working electrode and sample support. The probe surface was electrochemically modified with Pd, Re and the mixture of both. The electrolysis of gold was performed under galvanostatic control at 0.5 mA. Maximum pyrolysis temperature for the probe surface modified with Pd was 1200 deg. C, with Re 1300 deg. C. The relative standard deviation for the determination of 2 μg l -1 Au was not higher than 5.6% (n = 8) for 2 min electrodeposition. The sensitivity of gold determination was reproducible for 300 electrodeposition and atomization cycles. When the probe surface was modified with a mixture of Pd and Re the detection limit was 31 ng l -1 for 2 min electrodeposition, 3.7 ng l -1 for 30 min, 1.5 ng l -1 for 1 h and 0.4 ng l -1 for 4 h electrodeposition, respectively. The procedure was applied to the determination of gold in river water samples. The relative standard deviation for the determination of 2.5 ng l -1 Au at 4 h electrodeposition time at 0.5 mA was 7.5%

Gold 100: proceedings of the international conference on gold. V. 2

International Nuclear Information System (INIS)

Fivaz, C.E.; King, R.P.

1986-01-01

The proceedings of Gold 100 have been published in three separate volumes. The first deals with the mining of gold, the second with the extractive metallurgy of gold, and the third with industrial uses of gold. In this second volume, the papers on extractive metallurgy presented at the Conference reflect most of the problems that are currently of significant technical interest to the industry. This volume is divided in six main parts covering plant design, carbon-in-pulp technology, refractory gold, new technology, grinding and concentration, and leaching. The part on new technology includes papers on x-ray fluorescence analyzers, Moessbauer spectroscopy and leaching processes for uranium, while the part on grinding and concentration includes papers on nuclear and radiotracer techniques for the recovery of gold as well as various flotation parameters in the flotation behaviour of gold and uranium

A gold standard method for the evaluation of antibody-based materials functionality: Approach to forced degradation studies.

Science.gov (United States)

Coussot, Gaëlle; Le Postollec, Aurélie; Faye, Clément; Dobrijevic, Michel

2018-04-15

The scope of this paper is to present a gold standard method to evaluate functional activity of antibody (Ab)-based materials during the different phases of their development, after their exposure to forced degradations or even during routine quality control. Ab-based materials play a central role in the development of diagnostic devices, for example, for screening or therapeutic target characterization, in formulation development, and in novel micro(nano)technology approaches to develop immunosensors useful for the analysis of trace substances in pharmaceutical and food industries, clinical and environmental fields. A very important aspect in diagnostic device development is the construction of its biofunctional surfaces. These Ab surfaces require biocompatibility, homogeneity, stability, specificity and functionality. Thus, this work describes the validation and applications of a unique ligand binding assay to directly perform the quantitative measurement of functional Ab binding sites immobilized on the solid surfaces. The method called Antibody Anti-HorseRadish Peroxidase (A2HRP) method, uses a covalently coated anti-HRP antibody (anti-HRP Ab) and does not need for a secondary Ab during the detection step. The A2HRP method was validated and gave reliable results over a wide range of absorbance values. Analyzed validation criteria were fulfilled as requested by the food and drug administration (FDA) and European Medicines Agency (EMA) guidance for the validation of bioanalytical methods with 1) an accuracy mean value within +15% of the nominal value; 2) the within-assay precision less than 7.1%, and 3) the inter-day variability under 12.1%. With the A2HRP method, it is then possible to quantify from 0.04 × 10 12 to 2.98 × 10 12 functional Ab binding sites immobilized on the solid surfaces. A2HRP method was validated according to FDA and EMA guidance, allowing the creation of a gold standard method to evaluate Ab surfaces for their resistance under

Low-Impact Exploration for Gold in the Scottish Caledonides.

Science.gov (United States)

Rice, Samuel; Cuthbert, Simon; Hursthouse, Andrew; Broetto, Gabriele

2017-04-01

The Caledonian orogenic belt of the northern British Isles hosts some significant gold deposits. However, gold mineralization in the region is underexplored. Some of the most prospective areas identified by rich alluvial gold anomalies are environmentally and culturally sensitive. Traditional mineral exploration methods can have a range of negative environmental, social and economic impacts. The regional tourism economy is dependent on outdoor activities, landscape quality, wildlife and industrial heritage and has the potential to be disrupted by mineral resource developments. Low-cost, low-impact exploration strategies are therefore, key to sustainably developing the mineral resource potential. Research currently in progress in part of the Scottish Caledonides aims to develop protocols for more sustainable exploration. We are using a range of geoscience techniques to characterize the mineral system, improve exploration targeting and reduce negative impacts. To do this we targeted an area with a large preexisting dataset (e.g. stream sediment geochemistry, geomorphology, structural geology, petrology, geophysics, mine data) that can be synthesized and analyzed in a GIS. Part of the work aims to develop and test a model for gold dispersion in the surface environment that accounts for climatic and anthropogenic influences in order to locate bedrock sources. This multidisciplinary approach aims to reduce the target areas for subsequent exploration activities such as soil sampling, excavation and drilling.

Alteration mineral mapping using ETM+ and hyperion remote sensing data at Bau Gold Field, Sarawak, Malaysia

International Nuclear Information System (INIS)

Pour, A B; Hashim, M

2014-01-01

The area under investigation is the Bau gold mining district in the State of Sarawak, East Malaysia, on the island of Borneo. It has tropical climate with limited bedrock exposures. Bau is a gold field similar to Carlin style gold deposits. Geological analyses coupled with remote sensing data were used to detect hydrothermally altered rocks associated with gold mineralization. The Landsat Enhanced Thematic Mapper + (ETM + ) and Hyperion data were used to carry out mineral mapping of mineralized zones in the study area and surrounding terrain. Directed Principal Components Analysis (DPCA) transformation of four appropriate ETM+ band ratios were applied to produce DPC images, allowing the removal of the effects of vegetation from ETM+ data and the detection of separate mineral images at a regional scale. Linear Spectral Unmixing (LSU) was used to produce image maps of hydroxyl-bearing minerals using Hyperion data at a district scale. Results derived from the visible and near infrared and shortwave infrared bands of Hyperion represented iron oxide/hydroxide and clay minerals rich zones associated with the known gold prospects in the Bau district. The results show that the known gold prospects and potentially interesting areas are recognizable by the methods used, despite limited bedrock exposure in this region and the constraints imposed by the tropical environment. The approach used in this study can be more broadly applicable to provide an opportunity for detecting potentially interesting areas of gold mineralization using the ETM + and Hyperion data in the tropical/sub-tropical regions

Alteration mineral mapping using ETM+ and hyperion remote sensing data at Bau Gold Field, Sarawak, Malaysia

Science.gov (United States)

Pour, A. B.; Hashim, M.

2014-02-01

The area under investigation is the Bau gold mining district in the State of Sarawak, East Malaysia, on the island of Borneo. It has tropical climate with limited bedrock exposures. Bau is a gold field similar to Carlin style gold deposits. Geological analyses coupled with remote sensing data were used to detect hydrothermally altered rocks associated with gold mineralization. The Landsat Enhanced Thematic Mapper+ (ETM+) and Hyperion data were used to carry out mineral mapping of mineralized zones in the study area and surrounding terrain. Directed Principal Components Analysis (DPCA) transformation of four appropriate ETM+ band ratios were applied to produce DPC images, allowing the removal of the effects of vegetation from ETM+ data and the detection of separate mineral images at a regional scale. Linear Spectral Unmixing (LSU) was used to produce image maps of hydroxyl-bearing minerals using Hyperion data at a district scale. Results derived from the visible and near infrared and shortwave infrared bands of Hyperion represented iron oxide/hydroxide and clay minerals rich zones associated with the known gold prospects in the Bau district. The results show that the known gold prospects and potentially interesting areas are recognizable by the methods used, despite limited bedrock exposure in this region and the constraints imposed by the tropical environment. The approach used in this study can be more broadly applicable to provide an opportunity for detecting potentially interesting areas of gold mineralization using the ETM+ and Hyperion data in the tropical/sub-tropical regions.

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.

Indacaterol/glycopyrronium in symptomatic patients with COPD (GOLD B and GOLD D versus salmeterol/fluticasone: ILLUMINATE/LANTERN pooled analysis

Directory of Open Access Journals (Sweden)

Vogelmeier C

2016-12-01

Full Text Available Claus Vogelmeier,1 Nanshan Zhong,2 Michael J Humphries,3 Karen Mezzi,4 Robert Fogel,5 Giovanni Bader,4 Francesco Patalano,4 Donald Banerji5 1Department of Medicine, Pulmonary and Critical Care Medicine, University Medical Center Giessen and Marburg, Philipps-University Marburg, Member of the German Center for Lung Research (DZL, Marburg, Germany; 2State Key Laboratory, Guangzhou Institute of Respiratory Diseases, First Affiliated Hospital, Guangzhou Medical University, Guangzhou, 3Beijing Novartis Pharma Co. Ltd., Shanghai, People’s Republic of China; 4Novartis Pharma AG, Basel, Switzerland; 5Novartis Pharmaceuticals Corporation, East Hanover, NJ, USA Background: Indacaterol/glycopyrronium (IND/GLY is approved for maintenance treatment of adult patients with COPD. This post hoc analysis explored the efficacy and safety of IND/GLY versus salmeterol/fluticasone (SFC in symptomatic (Global Initiative for Chronic Obstructive Lung Disease [GOLD] B and GOLD D patients with moderate-to-severe COPD.Patients and methods: Data from LANTERN and ILLUMINATE studies were pooled and analyzed. In both studies, symptomatic COPD patients were randomized to once-daily IND/GLY 110 µg/50 µg or twice-daily SFC 50 µg/500 µg. End points were pre-dose trough forced expiratory volume in one second (FEV1, standardized area under the curve for FEV1 from 0 to 12 hours (FEV1 AUC0–12 hours, peak FEV1, peak forced vital capacity (FVC, pre-dose trough FVC, Transition Dyspnea Index (TDI total score, St George’s Respiratory Questionnaire total score, rescue medication use and safety.Results: A total of 1,263 patients were classified as either GOLD B (n=809 or GOLD D (n=454. At week 26, IND/GLY demonstrated statistically significant improvement in all lung function parameters versus SFC in patients in both the GOLD B and GOLD D subgroups. TDI total score and rescue medication use were significantly improved with IND/GLY versus SFC in the overall population and in the

Bio-synthesis of gold nanoparticles by human epithelial cells, in vivo

International Nuclear Information System (INIS)

Larios-Rodriguez, E; Rangel-Ayon, C; Herrera-Urbina, R; Castillo, S J; Zavala, G

2011-01-01

Healthy epithelial cells, in vivo, have the ability to synthesize gold nanoparticles when aqueous tetrachloroauric acid is made to react with human skin. Neither a reducing agent nor a protecting chemical is needed for this bio-synthesis method. The first indication of gold nanoparticle formation is the staining of the skin, which turns deep purple. Stereoscopic optical micrographs of human skin tissue in contact with aqueous tetrachloroauric acid clearly show the staining of the epithelial cells. The UV-Vis spectrum of these epithelial cells shows an absorption band with a maximum at 553 nm. This absorption peak is within the wavelength region where the surface plasmon resonance (SPR) band of aqueous colloidal gold exhibits a maximum. Transmission electron micrographs show that gold nanoparticles synthesized by epithelial cells have sizes between 1 and 100 nm. The electron diffraction pattern of these nanoparticles reveals a crystalline structure whose interplanar distances correspond to fcc metallic gold. Transmission electron micrographs of ultra-thin (70 nm thick) slices of epithelial cells clearly and undoubtedly demonstrate that gold nanoparticles are inside the cell. According to high resolution transmission electron micrographs of intracellular single gold nanoparticles, they have the shape of a polyhedron.

Bio-synthesis of gold nanoparticles by human epithelial cells, in vivo

Energy Technology Data Exchange (ETDEWEB)

Larios-Rodriguez, E; Rangel-Ayon, C; Herrera-Urbina, R [Departamento de Ingenieria Quimica y Metalurgia, Universidad de Sonora, Rosales y Luis Encinas S/N, Hermosillo, Sonora, C.P. 83000 (Mexico); Castillo, S J [Departamento de Investigacion en Fisica, Universidad de Sonora, Rosales y Luis Encinas S/N, Hermosillo, Sonora, C.P. 83000 (Mexico); Zavala, G, E-mail: elarios@polimeros.uson.mx [Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos (Mexico)

2011-09-02

Healthy epithelial cells, in vivo, have the ability to synthesize gold nanoparticles when aqueous tetrachloroauric acid is made to react with human skin. Neither a reducing agent nor a protecting chemical is needed for this bio-synthesis method. The first indication of gold nanoparticle formation is the staining of the skin, which turns deep purple. Stereoscopic optical micrographs of human skin tissue in contact with aqueous tetrachloroauric acid clearly show the staining of the epithelial cells. The UV-Vis spectrum of these epithelial cells shows an absorption band with a maximum at 553 nm. This absorption peak is within the wavelength region where the surface plasmon resonance (SPR) band of aqueous colloidal gold exhibits a maximum. Transmission electron micrographs show that gold nanoparticles synthesized by epithelial cells have sizes between 1 and 100 nm. The electron diffraction pattern of these nanoparticles reveals a crystalline structure whose interplanar distances correspond to fcc metallic gold. Transmission electron micrographs of ultra-thin (70 nm thick) slices of epithelial cells clearly and undoubtedly demonstrate that gold nanoparticles are inside the cell. According to high resolution transmission electron micrographs of intracellular single gold nanoparticles, they have the shape of a polyhedron.

Validation for 2D/3D registration II: The comparison of intensity- and gradient-based merit functions using a new gold standard data set

International Nuclear Information System (INIS)

Gendrin, Christelle; Markelj, Primoz; Pawiro, Supriyanto Ardjo; Spoerk, Jakob; Bloch, Christoph; Weber, Christoph; Figl, Michael; Bergmann, Helmar; Birkfellner, Wolfgang; Likar, Bostjan; Pernus, Franjo

2011-01-01

Purpose: A new gold standard data set for validation of 2D/3D registration based on a porcine cadaver head with attached fiducial markers was presented in the first part of this article. The advantage of this new phantom is the large amount of soft tissue, which simulates realistic conditions for registration. This article tests the performance of intensity- and gradient-based algorithms for 2D/3D registration using the new phantom data set. Methods: Intensity-based methods with four merit functions, namely, cross correlation, rank correlation, correlation ratio, and mutual information (MI), and two gradient-based algorithms, the backprojection gradient-based (BGB) registration method and the reconstruction gradient-based (RGB) registration method, were compared. Four volumes consisting of CBCT with two fields of view, 64 slice multidetector CT, and magnetic resonance-T1 weighted images were registered to a pair of kV x-ray images and a pair of MV images. A standardized evaluation methodology was employed. Targets were evenly spread over the volumes and 250 starting positions of the 3D volumes with initial displacements of up to 25 mm from the gold standard position were calculated. After the registration, the displacement from the gold standard was retrieved and the root mean square (RMS), mean, and standard deviation mean target registration errors (mTREs) over 250 registrations were derived. Additionally, the following merit properties were computed: Accuracy, capture range, number of minima, risk of nonconvergence, and distinctiveness of optimum for better comparison of the robustness of each merit. Results: Among the merit functions used for the intensity-based method, MI reached the best accuracy with an RMS mTRE down to 1.30 mm. Furthermore, it was the only merit function that could accurately register the CT to the kV x rays with the presence of tissue deformation. As for the gradient-based methods, BGB and RGB methods achieved subvoxel accuracy (RMS m

The Cox-maze IV procedure in its second decade: still the gold standard?

Science.gov (United States)

Ruaengsri, Chawannuch; Schill, Matthew R; Khiabani, Ali J; Schuessler, Richard B; Melby, Spencer J; Damiano, Ralph J

2018-04-01

Atrial fibrillation (AF) is the most common cardiac arrhythmia and the treatment options include medical treatment and catheter-based or surgical interventions. AF is a major cause of stroke, and its prevalence is increasing. The surgical treatment of AF has been revolutionized over the past 2 decades through surgical innovation and improvements in endoscopic imaging, ablation technology and surgical instrumentation. The Cox-maze (CM) procedure, which was developed by James Cox and introduced clinically in 1987, is a procedure in which multiple incisions are created in both the left and the right atria to eliminate AF while allowing the sinus impulse to reach the atrioventricular node. This procedure became the gold standard for the surgical treatment of AF. Its latest iteration is termed the CM IV and was introduced in 2002. The CM IV replaced the previous cut-and-sew method (CM III) by replacing most of the incisions with a combination of bipolar radiofrequency and cryoablation. The use of ablation technologies, made the CM IV technically easier, faster and more amenable to minimally invasive approaches. The aims of this article are to review the indications and preoperative planning for the CM IV, to describe the operative technique and to review the literature including comparisons of the CM IV with the previous cut-and-sew method. Finally, this review explores future directions for the surgical treatment of patients with AF.

Gold(I)-selenolate complexes: Synthesis, characterization and ...

Indian Academy of Sciences (India)

known that the gold(I) drugs rapidly bind to the most abundant plasma protein serum albumin (Alb-SH) after ... Aldrich. The experiments were carried out under dry and oxygen-free nitrogen using standard Schlenk tech- ... To a deoxygenated aqueous solution of the disele- nide 11 (30.0mg, 0.094mmol) was added sodium.

A special issue devoted to gold deposits in northern Nevada: Part 2. Carlin-type Deposits

Science.gov (United States)

Hofstra, Albert H.; John, David A.; Theodore, Ted G.

2003-01-01

This is the second of two special issues of Economic Geology devoted to gold deposits in northern Nevada. Readers interested in a general overview of these deposits, their economic significance, their context within the tectonic evolution of the region, and synoptic references on each gold deposit type are directed to the preface of the first special issue (John et al., 2003). Volume 98, issue 2, contains five papers that address regional aspects important to the genesis of gold deposits in northern Nevada and five papers that present detailed studies of epithermal deposits and districts. All of the regional papers are pertinent to Carlin-type gold deposits, because they address the age of mineralization (Arehart et al., 2003), origin and evolutionary history of the northwest-striking mineral belts that localize many deposits (Grauch et al., 2003), nature of the middle and lower crust below these mineral belts (Howard, 2003), district- to deposit-scale stream sediment and lithogeochemical anomalies (Theodore et al., 2003), and stratigraphy and structure of a district located along a northeast-striking lineament (Peters et al., 2003).

Standardization of education as essential to the development of regional educational systems

Directory of Open Access Journals (Sweden)

Shevchuk Andrey

2013-01-01

Full Text Available The problematic aspects of the current educational standards in Ukraine as important legal instruments of regional educational systems were viewed. The regulated areas of education standards in Ukraine and the traditional approach based on the identified areas of their innovative changes where described. The main directions of innovation education standards depending on their subject focus where systemised.

Neutron activation analysis of gold and prospectiveness of its application

International Nuclear Information System (INIS)

Tong Chunhan.

1988-01-01

NAA of gold is a method of high sensitivity and high percision, especially when epithermal neutron activation is applied. NAA is particularly emphasized in the process of gold reference standards preparation. In addition to the pure instrumental NAA, the NAA with pre-enrichment before sctivation is developed. This technque has been successfully used in assessment of micro and fine grained Au-Ag-phlymetal ores in Guixian, Guangxi. Through this example, prospectiveness of NAA application in Au-Ag-prospecting, fast assessment and trace element geochemistry investigation is seen

A multiplex microplatform for the detection of multiple DNA methylation events using gold-DNA affinity.

Science.gov (United States)

Sina, Abu Ali Ibn; Foster, Matthew Thomas; Korbie, Darren; Carrascosa, Laura G; Shiddiky, Muhammad J A; Gao, Jing; Dey, Shuvashis; Trau, Matt

2017-10-07

We report a new multiplexed strategy for the electrochemical detection of regional DNA methylation across multiple regions. Using the sequence dependent affinity of bisulfite treated DNA towards gold surfaces, the method integrates the high sensitivity of a micro-fabricated multiplex device comprising a microarray of gold electrodes, with the powerful multiplexing capability of multiplex-PCR. The synergy of this combination enables the monitoring of the methylation changes across several genomic regions simultaneously from as low as 500 pg μl -1 of DNA with no sequencing requirement.

78 FR 71448 - Regional Reliability Standard BAL-002-WECC-2-Contingency Reserve

Science.gov (United States)

2013-11-29

...; Order No. 789] Regional Reliability Standard BAL-002-WECC-2--Contingency Reserve AGENCY: Federal Energy... (Contingency Reserve). The North American Electric Reliability Corporation (NERC) and Western Electricity... Region and is meant to specify the quantity and types of [[Page 71449

Enhancement of gold recovery using bioleaching from gold concentrate

Science.gov (United States)

Choi, S. H.; Cho, K. H.; Kim, B. J.; Choi, N. C.; Park, C. Y.

2012-04-01

The gold in refractory ores is encapsulated as fine particles (sometimes at a molecular level) in the crystal structure of the sulfide (typically pyrite with or without arsenopyrite) matrix. This makes it impossible to extract a significant amount of refractory gold by cyanidation since the cyanide solution cannot penetrate the pyrite/arsenopyrite crystals and dissolve gold particles, even after fine grinding. To effectively extract gold from these ores, an oxidative pretreatment is necessary to break down the sulfide matrix. The most popular methods of pretreatment include nitric acid oxidation, roasting, pressure oxidation and biological oxidation by microorganisms. This study investigated the bioleaching efficiency of Au concentrate under batch experimental conditions (adaptation cycles and chemical composition adaptation) using the indigenous acidophilic bacteria collected from gold mine leachate in Sunsin gold mine, Korea. We conducted the batch experiments at two different chemical composition (CuSO4 and ZnSO4), two different adaptation cycles 1'st (3 weeks) and 2'nd (6 weeks). The results showed that the pH in the bacteria inoculating sample decreased than initial condition and Eh increased. In the chemical composition adaptation case, the leached accumulation content of Fe and Pb was exhibited in CuSO4 adaptation bacteria sample more than in ZnSO4 adaptation bacteria samples, possibly due to pre-adaptation effect on chalcopyrite (CuFeS2) in gold concentrate. And after 21 days on the CuSO4 adaptation cycles case, content of Fe and Pb was appeared at 1'st adaptation bacteria sample(Fe - 1.82 and Pb - 25.81 times per control sample) lower than at 2'nd adaptation bacteria sample(Fe - 2.87 and Pb - 62.05 times per control sample). This study indicates that adaptation chemical composition and adaptation cycles can play an important role in bioleaching of gold concentrate in eco-/economic metallurgy process.

Enrichment of Gold in Antimony Matte by Direct Smelting of Refractory Gold Concentrate

Science.gov (United States)

Yang, Tianzu; Xie, Boyi; Liu, Weifeng; Zhang, Duchao; Chen, Lin

2018-06-01

Conventional cyanidation technology achieves low gold recovery when used to process refractory gold concentrate. Based on the geochemical characteristics of gold deposit mineralization, a new method is proposed herein for gold enrichment in antimony matte by smelting of refractory gold concentrate. The effects of the FeO/SiO2 and CaO/SiO2 ratios, smelting temperature, and smelting time on the gold recovery were investigated in detail. The optimum conditions were determined to be FeO/SiO2 ratio of 1.2, CaO/SiO2 ratio of 0.4, smelting temperature of 1200°C, and smelting time of 45 min. The gold content in antimony matte and smelting slag was 96.68 and 1.13 g/t, respectively. The gold, antimony, and arsenic recovery was 97.72%, 26.89%, and 6.56%, respectively, with most of the antimony and arsenic volatilized into dust. Mineral liberation analyzer results showed that the antimony matte mainly consisted of FeS and FeO, with three phases, viz. FeAs, SbAs, and AuSb, embedded between them, indicating that gold was easily enriched with antimony and arsenic during smelting of refractory gold concentrate.

Enrichment of Gold in Antimony Matte by Direct Smelting of Refractory Gold Concentrate

Science.gov (United States)

Yang, Tianzu; Xie, Boyi; Liu, Weifeng; Zhang, Duchao; Chen, Lin

2018-04-01

Conventional cyanidation technology achieves low gold recovery when used to process refractory gold concentrate. Based on the geochemical characteristics of gold deposit mineralization, a new method is proposed herein for gold enrichment in antimony matte by smelting of refractory gold concentrate. The effects of the FeO/SiO2 and CaO/SiO2 ratios, smelting temperature, and smelting time on the gold recovery were investigated in detail. The optimum conditions were determined to be FeO/SiO2 ratio of 1.2, CaO/SiO2 ratio of 0.4, smelting temperature of 1200°C, and smelting time of 45 min. The gold content in antimony matte and smelting slag was 96.68 and 1.13 g/t, respectively. The gold, antimony, and arsenic recovery was 97.72%, 26.89%, and 6.56%, respectively, with most of the antimony and arsenic volatilized into dust. Mineral liberation analyzer results showed that the antimony matte mainly consisted of FeS and FeO, with three phases, viz. FeAs, SbAs, and AuSb, embedded between them, indicating that gold was easily enriched with antimony and arsenic during smelting of refractory gold concentrate.

The geology of the gold deposits of Prestea gold belt of Ghana ...

African Journals Online (AJOL)

This paper presents the geology of the gold deposits along the Prestea gold belt of Ghana to assist exploration work for new orebodies along the belt. Prestea district is the third largest gold producer in West Africa after Obuasi and Tarkwa districts (over 250 metric tonnes Au during the last century). The gold deposits are ...

Causes and consequences of a tropical forest gold rush in the Guiana Shield, South America.

Science.gov (United States)

Hammond, David S; Gond, Valéry; de Thoisy, Benoit; Forget, Pierre-Michel; DeDijn, Bart P E

2007-12-01

Statistical and spatial analyses of both historical time series and remotely sensed data show a link between the spatial distribution and growth of gold production across the Guiana Shield in northeast Amazonia. Results indicate that an exponential rise in production across an expanding area is primarily a delayed response to the 1971-1978 market flotation of international gold prices. The subsequent 10-fold (2-fold) average nominal (real) price increase has provided a compelling economic incentive to mass exploitation of lower-grade gold deposits. The ground-based and remotely sensed distributions of mining activity are strongly attached to these deposits that dominate the region's gold geology. The presence of these gold-bearing formations in conservation and sustainable timber zones has sparked social conflict and environmental degradation across the region. Left unmanaged, more than a quarter-million square-kilometer area of tropical forest zoned for protection and sustainable management could ultimately be compromised by the price-driven boom in gold mining through poorly integrated resource use planning, lack of reclamation effort, and control of illegal operations. Serious public health issues propagated through the unregulated mining environment further erode the financial benefits achieved through gold extraction. This study demonstrates in part how international economic policies successfully stabilizing more conspicuous centers of the global economy can have unintended but profound environmental and social impacts on remote commodity frontiers.

Spatio-selective surface modification of glass assisted by laser-induced deposition of gold nanoparticles

International Nuclear Information System (INIS)

Takahashi, Hironobu; Niidome, Yasuro; Hisanabe, Hideyuki; Kuroiwa, Keita; Kimizuka, Nobuo; Yamada, Sunao

2006-01-01

Using pulsed laser irradiation (532 nm), dodecanethiol-capped gold nanoparticles (DT-Au) were deposited on the laser-irradiated region of a hydrophobic glass substrate modified with dimethyloctadecylchlorosilane (DMOS). After removal of deposited DT-Au, the laser-deposited region on the substrate was hydrophilic, as verified by static water contact angles. X-ray photoelectron spectroscopy suggested that the naked glass surface was not exposed at the hydrophilic region. Immersion of the substrate into gold nanorod (NR) solution selectively immobilized NRs on the hydrophilic surface via electrostatic interactions, indicating that the hydrophilic region was an anionic surface. From these results, it is expected that some immobilized DMOS groups on the laser-irradiated region of the substrate were oxidized during DT-Au deposition and fragmentation of the deposited DT-Au

Characterization of scale contrast of gold nanoparticles with the use of clinical computed tomography

International Nuclear Information System (INIS)

Badelli, Juliana C.; Miquellin, Charlie A.; Bezerra, Arandi G.; Orsato, Alexandre; Woiski, Thiago D.; Figueiredo, Bonald C.

2015-01-01

Binding nanoparticles with antibodies that have protein with affinity cancer cells, then insert them into a diseased tissue, the antibodies will lead the nanoparticles to the region with malignant cells. Being possible to see the committed region, the size of tissue involvement and if is occurring metastasis with diagnostic imaging methods. This study aimed to evaluate how you distributed the contrast range of a set of concentrations of gold nanoparticles (NP) using existing protocols in clinical computed tomography equipment. For the irradiation of NP was made a support in HDPE . Different concentrations of NP form prepared ranging from 0.01 to 10 mg / ml , and samples of distilled water , and calcium. The standard protocols of cranium and abdomen of a Toshiba equipment Aquillion 64 were used for obtaining the CT numbers (HU). The theoretical HU value of Gold nanoparticles for beam energy used was 47.4 HU calculated and compared with the values found . Of the results was not possible to notice a growing response from the HU NP as a function of increasing concentration, however you can view a range of HU according to these concentrations . Of different concentrations of 5 mg / mL is the one closest to the theoretical value obtained. These results are promising and demonstrate that there is a need for further experiments with the NP and the tomograph. (author)

Characterization of scale contrast of gold nanoparticles with the use of clinical computed tomography

Energy Technology Data Exchange (ETDEWEB)

Badelli, Juliana C.; Miquellin, Charlie A.; Bezerra, Arandi G., E-mail: jubadellin@gmail.com, E-mail: charlie@utfpr.edu.br, E-mail: arandi@utfpr.edu.br [Universidade Tecnologica Federal do Parana (CPGEI/UTFPR), Curitiba, PR (Brazil); Orsato, Alexandre; Woiski, Thiago D.; Figueiredo, Bonald C., E-mail: orsato_ale@yahoo.co.uk, E-mail: Thiagodw@ibest.com.br [Instituto de Pesquisa Pele Pequeno Principe, Curitiba PR (Brazil)

2015-07-01

Binding nanoparticles with antibodies that have protein with affinity cancer cells, then insert them into a diseased tissue, the antibodies will lead the nanoparticles to the region with malignant cells. Being possible to see the committed region, the size of tissue involvement and if is occurring metastasis with diagnostic imaging methods. This study aimed to evaluate how you distributed the contrast range of a set of concentrations of gold nanoparticles (NP) using existing protocols in clinical computed tomography equipment. For the irradiation of NP was made a support in HDPE . Different concentrations of NP form prepared ranging from 0.01 to 10 mg / ml , and samples of distilled water , and calcium. The standard protocols of cranium and abdomen of a Toshiba equipment Aquillion 64 were used for obtaining the CT numbers (HU). The theoretical HU value of Gold nanoparticles for beam energy used was 47.4 HU calculated and compared with the values found . Of the results was not possible to notice a growing response from the HU NP as a function of increasing concentration, however you can view a range of HU according to these concentrations . Of different concentrations of 5 mg / mL is the one closest to the theoretical value obtained. These results are promising and demonstrate that there is a need for further experiments with the NP and the tomograph. (author)

Gold Leaching Characteristics and Intensification of a High S and As-Bearing Gold Concentrate

Science.gov (United States)

Yang, Yong-bin; Liu, Xiao-liang; Jiang, Tao; Li, Qian; Xu, Bin; Zhang, Yan

Some high sulfur and arsenic-bearing gold concentrate has a gold leaching rate less than 80% by oxidation roasting-pickling-cyanidation process. The characteristics and intensification of gold leaching were studied systemically. By combining chemical composition and phase analysis, the low gold leaching rate was found to lie in the capsulation of gold by iron-containing phases including iron oxides, arsenopyrite and pyrite. 96.66% of gold in the industrial leaching residue was capsulated and 95.88% of the capsulated turned out to be in the iron-containing phases. The results of laboratory pickling-cyanidation experiments on the calcine and industrial leaching residue presented further demonstration for the fact that gold capsulated in the iron-containing phases was hard to be leached. However, the gold cyanide leaching rate of calcine could be raised over 95% by a reduction roasting-pickling pretreatment which played such a significant role in exposing the capsulated gold that gold leaching was intensified remarkably.

Mercury exposure in a high fish eating Bolivian Amazonian population with intense small-scale gold-mining activities.

Science.gov (United States)

Barbieri, Flavia Laura; Cournil, Amandine; Gardon, Jacques

2009-08-01

Methylmercury exposure in Amazonian communities through fish consumption has been widely documented in Brazil. There is still a lack of data in other Amazonian countries, which is why we conducted this study in the Bolivian Amazon basin. Simple random sampling was used from a small village located in the lower Beni River, where there is intense gold mining and high fish consumption. All participants were interviewed and hair samples were taken to measure total mercury concentrations. The hair mercury geometric mean in the general population was 3.02 microg/g (CI: 2.69-3.37; range: 0.42-15.65). Age and gender were not directly associated with mercury levels. Fish consumption showed a positive relation and so did occupation, especially small-scale gold mining. Hair mercury levels were lower than those found in Brazilian studies, but still higher than in non-exposed populations. It is necessary to assess mercury exposure in the Amazonian regions where data is still lacking, using a standardized indicator.

Oxidation state of gold and arsenic in gold-bearing arsenian pyrite

Energy Technology Data Exchange (ETDEWEB)

Simon, G.; Huang, H.; Penner-Hahn, J.E.; Kesler, S.E.; Kao, L.S. [Univ. of Michigan, Ann Arbor, MI (United States)

1999-07-01

XANES measurements on gold-bearing arsenian pyrite from the Twin Creeks Carlin-type gold deposits show that gold is present as both Au{sup 0} and Au{sup 1+} and arsenic is present as As{sup 1{minus}}. Au{sup 0} is attributed to sub-micrometer size inclusions of free gold, whereas Au{sup 1+} is attributed to gold in the lattice of the arsenian pyrite. STEM observations suggest that As{sup 1{minus}} is probably concentrated in angstrom-scale, randomly distributed layers with a marcasite or arsenopyrite structure. Ionic gold (Au{sup 1+}) could be concentrated in these layers as well, and is present in both twofold- and fourfold-coordinated forms, with fourfold-coordinated Au{sup 1+} more abundant. Twofold-coordinated Au{sup 1+} is similar to gold in Au{sub 2}S in which it is linearly coordinated to two sulfur atoms. The nature of fourfold-coordinated Au{sup 1+} is not well understood, although it might be present as an Au-As-S compound where gold is bonded in fourfold coordination to sulfur and arsenic atoms, or in vacancy positions on a cation site in the arsenian pyrite. Au{sup 1+} was probably incorporated into arsenian pyrite by adsorption onto pyrite surfaces during crystal growth. The most likely compound in the case of twofold-coordinated Au{sup 1+} was probably a tri-atomic surface complex such as S{sub pyrite}-Au{sup 1+}-S{sub bi-sulfide}H or Au{sup 1+}-S-Au{sup 1+}. The correlation between gold and arsenic might be related to the role of arsenic in enhancing the adsorption of gold complexes of this type on pyrite surfaces, possibly through semiconductor effects.

Gold internal standard correction for elemental imaging of soft tissue sections by LA-ICP-MS: element distribution in eye microstructures.

Science.gov (United States)

Konz, Ioana; Fernández, Beatriz; Fernández, M Luisa; Pereiro, Rosario; González, Héctor; Alvarez, Lydia; Coca-Prados, Miguel; Sanz-Medel, Alfredo

2013-04-01

Laser ablation coupled to inductively coupled plasma mass spectrometry has been developed for the elemental imaging of Mg, Fe and Cu distribution in histological tissue sections of fixed eyes, embedded in paraffin, from human donors (cadavers). This work presents the development of a novel internal standard correction methodology based on the deposition of a homogeneous thin gold film on the tissue surface and the use of the (197)Au(+) signal as internal standard. Sample preparation (tissue section thickness) and laser conditions were carefully optimized, and internal normalisation using (197)Au(+) was compared with (13)C(+) correction for imaging applications. (24)Mg(+), (56)Fe(+) and (63)Cu(+) distributions were investigated in histological sections of the anterior segment of the eye (including the iris, ciliary body, cornea and trabecular meshwork) and were shown to be heterogeneously distributed along those tissue structures. Reproducibility was assessed by imaging different human eye sections from the same donor and from ten different eyes from adult normal donors, which showed that similar spatial maps were obtained and therefore demonstrate the analytical potential of using (197)Au(+) as internal standard. The proposed analytical approach could offer a robust tool with great practical interest for clinical studies, e.g. to investigate trace element distribution of metals and their alterations in ocular diseases.

Bismuth-silver mineralization in the Sergozerskoe gold occurrence

Directory of Open Access Journals (Sweden)

Kalinin A. A.

2017-03-01

Full Text Available Bismuth-silver mineralization attendant to gold mineralization in the Sergozerskoe gold occurrence has been studied in detail. Bi-Ag mineralization is connected with diorite porphyry dykes, which cut volcanic-sedimentary Lopian complexes of the Strel'ninsky greenstone belt – hornblendite and actinolite-chlorite amphibolites, biotite and bi-micaceous gneisses. Distribution of Bi-Ag mineralization similar to gold mineralization is controlled by 80 m thick zone of silicification. Bi minerals are found in brecciated diorite porphyry. Bismuth-silver mineralization includes native metals (bismuth, electrum, silver, tellurides (hedleyite, hessite, selenides (ikunolite, sulfides and sulfosalts of Bi and Ag (matildite, lillianite, eckerite, jalpaite, prustite, acanthite, a few undiagnosed minerals. All Bi and Ag minerals associate with galena. Composition of mineralization evolved from early to late stages of development, depending on intensity of rock alteration. The earliest Bi-Ag minerals were native bismuth and hedleyite formed dissemination in galena, and electrum with 30-45 mass.% Au. Later native bismuth was partly substituted by silver and bismuth sulfosalts and bismuth sulfides. The latest minerals were low-temperature silver sulfides eckerite, jalpaite, and acanthite, which were noted only in the most intensively altered rocks. As soon as the process of formation of Bi-Ag mineralization is the same as formation of gold, findings of bismuth-silver mineralization can serve as a positive exploration sign for gold in the region.

Synthesis and characterization of pHLIP® coated gold nanoparticles.

Science.gov (United States)

Daniels, Jennifer L; Crawford, Troy M; Andreev, Oleg A; Reshetnyak, Yana K

2017-07-01

Novel approaches in synthesis of spherical and multispiked gold nanoparticles coated with polyethylene glycol (PEG) and pH Low Insertion Peptide (pHLIP ® ) were introduced. The presence of a tumor-targeting pHLIP ® peptide in the nanoparticle coating enhances the stability of particles in solution and promotes a pH-dependent cellular uptake. The spherical particles were prepared with sodium citrate as a gold reducing agent to form particles of 7.0±2.5 nm in mean metallic core diameter and ∼43 nm in mean hydrodynamic diameter. The particles that were injected into tumors in mice (21 µg of gold) were homogeneously distributed within a tumor mass with no staining of the muscle tissue adjacent to the tumor. Up to 30% of the injected gold dose remained within the tumor one hour post-injection. The multispiked gold nanoparticles with a mean metallic core diameter of 146.0±50.4 nm and a mean hydrodynamic size of ~161 nm were prepared using ascorbic acid as a reducing agent and disk-like bicelles as a template. Only the presence of a soft template, like bicelles, ensured the appearance of spiked nanoparticles with resonance in the near infrared region. The irradiation of spiked gold nanoparticles by an 805 nm laser led to the time- and concentration-dependent increase of temperature. Both pHLIP ® and PEG coated gold spherical and multispiked nanoparticles might find application in radiation and thermal therapies of tumors.

Synthesis and characterization of pHLIP® coated gold nanoparticles

Directory of Open Access Journals (Sweden)

Jennifer L. Daniels

2017-07-01

Full Text Available Novel approaches in synthesis of spherical and multispiked gold nanoparticles coated with polyethylene glycol (PEG and pH Low Insertion Peptide (pHLIP® were introduced. The presence of a tumor-targeting pHLIP® peptide in the nanoparticle coating enhances the stability of particles in solution and promotes a pH-dependent cellular uptake. The spherical particles were prepared with sodium citrate as a gold reducing agent to form particles of 7.0±2.5 nm in mean metallic core diameter and ∼43 nm in mean hydrodynamic diameter. The particles that were injected into tumors in mice (21 µg of gold were homogeneously distributed within a tumor mass with no staining of the muscle tissue adjacent to the tumor. Up to 30% of the injected gold dose remained within the tumor one hour post-injection. The multispiked gold nanoparticles with a mean metallic core diameter of 146.0±50.4 nm and a mean hydrodynamic size of ~161 nm were prepared using ascorbic acid as a reducing agent and disk-like bicelles as a template. Only the presence of a soft template, like bicelles, ensured the appearance of spiked nanoparticles with resonance in the near infrared region. The irradiation of spiked gold nanoparticles by an 805 nm laser led to the time- and concentration-dependent increase of temperature. Both pHLIP® and PEG coated gold spherical and multispiked nanoparticles might find application in radiation and thermal therapies of tumors.

75 FR 36385 - Reliability Standards Development and NERC and Regional Entity Enforcement Supplemental Notice of...

Science.gov (United States)

2010-06-25

... Standards Development and NERC and Regional Entity Enforcement Supplemental Notice of Technical Conference... development and enforcement of mandatory Reliability Standards for the Bulk-Power System by the North American Electric Reliability Corporation and the Regional Entities. The conference will be held on Tuesday, July 6...

Metallogenesis of Precambrian gold deposits in the Wutai greenstone belt: Constrains on the tectonic evolution of the North China Craton

Directory of Open Access Journals (Sweden)

Ju-Quan Zhang

2018-03-01

Full Text Available The Wutai greenstone belt in central North China Craton (NCC hosts a number of Precambrian gold deposits and ore occurrences. Based on the host rock association, these can be divided into Banded Iron Formation (BIF, meta-volcano-sedimentary and meta-conglomerate types. The two former types formed during ∼2.5–2.3 Ga and the third one at ∼1.85 Ga. The characteristics of these Precambrian gold deposits are broadly similar with those of the orogenic gold deposits. Based on available geochronological data, here we reconstruct the major tectonic events and their relationship with gold mineralization in the Wutai-Hengshan-Fuping region during Neoarchean to Paleoproterozoic as follows. (1 ∼2.6–2.5 Ga: widespread intrusion of tonalite-trondhjemite-granodiorite (TTG magmas in the Hengshan terrane and Fuping continental arc, formation of the Wutai volcanic arc in the southern margin of Hengshan terrane with granitoids emplacement, and the Hengshan-Wutai intra-oceanic arc accretion to the Fuping arc at the end of Neoarchean. (2 ∼2.5–2.3 Ga: the subduction of Hengshan arc from north leading to persistent magmatism and orogenic gold mineralization. (3 ∼2.2–2.1 Ga: extension leading to the formation of graben structure in the Wutai and Fuping region, deposition of the Hutuo and Wanzi Group sediments, formation of placer gold through erosion of the orogenic gold deposits. (4 ∼2.2–2.0 Ga: widespread magmatism in the Wutai-Hengshan-Fuping region. (5 ∼1.95–1.8 Ga: regional metamorphism associated with collision of the Western and Eastern Blocks of the NCC and associated orogenic gold deposits. The multiple subduction-accretion-collision history and subsequent deep erosion has significantly affected most of the Precambrian gold deposits in the Wutai greenstone belt.

Quantification of captopril in urine through surface-assisted laser desorption/ionization mass spectrometry using 4-mercaptobenzoic acid-capped gold nanoparticles as an internal standard.

Science.gov (United States)

Chen, Wen-Tsen; Chiang, Cheng-Kang; Lin, Yang-Wei; Chang, Huan-Tsung

2010-05-01

We have developed a new internal standard method for the determination of the concentration of captopril (CAP) through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using gold nanoparticles (Au NPs). This approach provided linearity for CAP over the concentration range 2.5-25 microM (R(2) = 0.987), with a limit of detection (signal-to-noise ratio = 3) of 1.0 microM. The spot-to-spot variations in the concentration of CAP through SALDI-MS analyses performed in the absence and presence of the internal standard were 26% and 9%, respectively (15 measurements). This approach provides simplicity, accuracy, precision, and great reproducibility to the determination of the levels of CAP in human urine samples. Copyright 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

Coal-oil gold agglomeration assisted flotation to recover gold from refractory ore

Science.gov (United States)

Otsuki, A.; Yue, C.

2017-07-01

This study aimed to investigate the applicability of coal-oil gold agglomeration (CGA) assisted flotation to recover gold from a refractory ore. The ore with the grade of 2-5 g/t was tested with the CGA-flotation process in six different size fractions from 38 to 300 urn using different collector types and dosages. In addition, the flotation without CGA was performed under the same condition for comparison. The results showed that the higher gold grade and recovery were achieved by applying the CGA-flotation, compared with the flotation without CGA. More than 20-60 times grade increase from the head grade was obtained with CGA-flotation. The elemental analysis of gold and sulphur explained their relationship with gold recovery. The results well indicated the applicability of CGA to upgrade the refractory gold ore.

Validity of ultrasonography and measures of adult shoulder function and reliability of ultrasonography in detecting shoulder synovitis in patients with rheumatoid arthritis using magnetic resonance imaging as a gold standard.

LENUS (Irish Health Repository)

Bruyn, G A W

2010-08-01

To assess the intra- and interobserver reproducibility of musculoskeletal ultrasonography (US) in detecting inflammatory shoulder changes in patients with rheumatoid arthritis, and to determine the agreement between US and the Shoulder Pain and Disability Index (SPADI) and the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire, using magnetic resonance imaging (MRI) as a gold standard.

isotopic chronological study on gold-stibium deposits in Bayinbuluke area of Tianshan mountains

International Nuclear Information System (INIS)

Chen Fuwen; Li Huaqin

2003-01-01

Several gold-stibium deposits have recently been found in Bayinbuluke area of Tianshan Mountains, such as the Dashankou gold deposit and Chahansala stibium deposit. isotopic chronological study of mineralization show that the fluid inclusion Rb-Sr isochron age for gold-bearing pyrite-quartz veins and pyrite-limonite-quartz veins from the Dashankou gold mine are 354 ± 8.1 Ma (2 σ) and 344 ± 21 Ma (2 σ), respectively. The two ages are consistent in test errors, indicating the gold deposit was formed in early Carboniferous and related to regional shearing; the fluid inclusion Rb-Sr isochron age for quartz-stibnite veins and quartz-tetrahedrite-bismuthinite-stibnite veins from the Chahansala stibium mine is 257 ± 23 Ma (2 σ), indicating the deposit was formed during the late Hercynian-Early Indosinian Period and related to intracontinental deformation. (authors)

Challenges with minimising mercury pollution in the small-scale gold mining sector: experiences from the Guianas.

Science.gov (United States)

Hilson, Gavin; Vieira, Rickford

2007-12-01

This paper examines the barriers to mitigating mercury pollution at small-scale gold mines in the Guianas (Guyana, French Guiana and Suriname), and prescribes recommendations for overcoming these obstacles. Whilst considerable attention has been paid to analysing the environmental impacts of operations in the region, minimal research has been undertaken to identify appropriate policy and educational initiatives for addressing the mounting mercury problem. Findings from recent fieldwork and selected interviews with operators from Guyanese and Surinamese gold mining regions reveal that legislative incapacity, the region's varied industry policy stances, various technological problems, and low environmental awareness on the part of communities are impeding efforts to facilitate improved mercury management at small-scale gold mines in the Guianas. Marked improvements can be achieved, however, if legislation, particularly that pertaining to mercury, is harmonised in the region; educational seminars continue to be held in important mining districts; and additional outlets for disseminating environmental equipment and mercury-free technologies are provided.

Tectonic setting of synorogenic gold deposits of the Pacific Rim

Science.gov (United States)

Goldfarb, R.J.; Phillips, G.N.; Nokleberg, W.J.

1998-01-01

batholith have yielded more than 100 million oz of gold. Additional significant ore-forming events during the development of North America's Cordilleran orogen included those in the Klamath Mountains region, California in the Late Jurassic and Early Cretaceous; the Klondike district, Yukon by the Early Cretaceous; the Nome and Fairbanks districts, Alaska, and the Bridge River district, British Columbia in the middle Cretaceous; and the Juneau gold belt, Alaska in the Eocene. Gold-bearing veins deposited during the Late Jurassic and Early Cretaceous terrane collision that formed the present-day Russian Far East have been the source for more than 130 million oz of placer gold. The abundance of gold-bearing quartz-carbonate veins throughout the Gondwanan, North American and Eurasian continental margins suggests the migration and concentration of large fluid volumes during continental growth. Such volumes could be released during orogenic heating of hydrous silicate mineral phases within accreted marine strata. The common temporal association between gold veining and magmatism around the Pacific Rim reflects these thermal episodes. Melting of the lower thickened crust during arc formation, slab rollback and extensional tectonism, and subduction of a slab window beneath the seaward part of the forearc region can all provide the required heat for initation of the ore-forming processes.

Gold and gold-copper nanoparticles in 2-propanol: A radiation chemical study

International Nuclear Information System (INIS)

Dey, G.R.

2011-01-01

The studies on the reduction of Au 3+ to gold nanoparticles in presence and absence of Cu 2+ under deoxygenated conditions in 2-propanol by radiolytic method have been carried out. On γ-radiolysis, preliminary yellow colored solution of Au 3+ changed to purple color owing to gold nanoparticles formation, which exhibits an absorption peak at around 540 nm. In the presence of Cu 2+ , absorption of gold-copper nanoparticles, which was also produced during γ-radiolysis, was red shifted in contrast to the system containing no Cu 2+ . Under DLS studies the sizes of gold nanoparticles in the absence and the presence of Cu 2+ were found to be larger (>400 nm). However, in presence of polyethylene glycol, a stabilizer the nanoparticle sizes became smaller, sizes measured for gold and gold-copper nanoparticles are 40 and 140 nm, respectively. Moreover, the change in UV-vis spectra in the Cu 2+ and Au 3+ mixed system highlights the formation of gold-copper nanoparticles in core-shell type arrangement. - Highlights: → Present radiation chemical study highlights high reactivity of Au ·2+ with Cu 2+ . → Absorption of gold-copper nanoparticles is blue shifted as compared to copper nanoparticles. → Change in UV-vis spectra with dose emphasizes core-shell type arrangement of Au-Cu nanoparticles.

Gold in plants

International Nuclear Information System (INIS)

Girling, C.A.; Peterson, P.J.

1980-01-01

Many plants have the ability to take up gold from the soil and to accumulate it in their tisssue. Advances have been made in understanding these processes to the point where their exploitation in the field of prospecting for gold appears practically feasible. Neutron activation analysis is used for the determination of the small quantities of gold in plants

Distribution and composition of gold in porphyry gold systems: example from the Biely Vrch deposit, Slovakia

Science.gov (United States)

Koděra, Peter; Kozák, Jaroslav; Brčeková, Jana; Chovan, Martin; Lexa, Jaroslav; Jánošík, Michal; Biroň, Adrián; Uhlík, Peter; Bakos, František

2018-03-01

The Biely Vrch deposit in the Western Carpathians is assigned to the shallow, sulfide-poor porphyry gold deposit type and has an exceptionally low Cu/Au ratio. According to 3-D geochemical models, there is a limited spatial correlation between Au and Cu due to the primary introduction of gold by a salt melt and Cu by low-density vapor. Despite a rough spatial correlation of gold grades with quartz stockwork intensity, gold is hosted mostly by altered rock, exclusively in native form. Three main gold mineral assemblages were recognized here. In the deepest parts of the system, the K- and Ca-Na silicate gold assemblage is associated with minerals of high-temperature alteration (plagioclase, K-feldspar, actinolite), with gold grades and fineness depending on depth and potassium content of the host rock: K-silicate alteration hosts the lowest fineness gold ( 914), whereas Ca-Na silicate alteration has the highest ( 983). The intermediate argillic gold assemblage is the most widespread, with gold hosted mainly by chlorite, illite, smectite, and interstratified illite-chlorite-smectite minerals. The gold fineness is mostly variable (875-990) and inherited from the former gold mineral assemblages. The latest advanced argillic gold assemblage has its gold mostly in kaolinite. The extremely high fineness ( 994) results from gold remobilization by late-stage aqueous magmatic-hydrothermal fluids. Uncommon bonanza-grade appears where the earlier gold mineral assemblages were further enriched by this remobilized gold. Primary precipitation of gold occurred during ascent and cooling of salt melts at 450 to 309 °C, mostly during retrograde quartz solubility.

Composition and genesis of the Konevinsky gold deposit, Eastern Sayan, Russia

Science.gov (United States)

Damdinov, B. B.; Zhmodik, S. M.; Roshchektaev, P. A.; Damdinova, L. B.

2016-03-01

The Konevinsky gold deposit in southeast Eastern Sayan is distinguished from most known deposits in this region (Zun-Kholba, etc.) by the geological setting and composition of mineralization. To elucidate the cause of the peculiar mineralization, we have studied the composition, formation conditions, and origin of this deposit, which is related to the Ordovician granitoid pluton 445-441 Ma in age cut by intermediate and basic dikes spatially associated with metavolcanic rocks of the Devonian-Carboniferous Ilei Sequence. Four mineral assemblages are recognized: (1) quartz-pyrite-molybdenite, (2) quartz-gold-pyrite, (3) gold-polysulfide, and (4) telluride. Certain indications show that the ore was formed as a result of the superposition of two distinct mineral assemblages differing in age. The first stage dated at ~440 Ma is related to intrusions generating Cu-Mo-Au porphyry mineralization and gold-polysulfide veins. The second stage is controlled by dikes pertaining to the Devonian-Carboniferous volcanic-plutonic association. The second stage is characterized by gain of Hg and Te and formation of gold-mercury-telluride paragenesis.

40 CFR 440.104 - New source performance standards (NSPS).

Science.gov (United States)

2010-07-01

... GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Copper, Lead, Zinc, Gold, Silver, and... copper, lead, zinc, gold, silver, or molybdenum bearing ores or any combination of these ores from open... discharge of process wastewater to navigable waters from mills that use the froth-flotation process alone...

Implementing standards for the interoperability among healthcare providers in the public regionalized Healthcare Information System of the Lombardy Region.

Science.gov (United States)

Barbarito, Fulvio; Pinciroli, Francesco; Mason, John; Marceglia, Sara; Mazzola, Luca; Bonacina, Stefano

2012-08-01

Information technologies (ITs) have now entered the everyday workflow in a variety of healthcare providers with a certain degree of independence. This independence may be the cause of difficulty in interoperability between information systems and it can be overcome through the implementation and adoption of standards. Here we present the case of the Lombardy Region, in Italy, that has been able, in the last 10 years, to set up the Regional Social and Healthcare Information System, connecting all the healthcare providers within the region, and providing full access to clinical and health-related documents independently from the healthcare organization that generated the document itself. This goal, in a region with almost 10 millions citizens, was achieved through a twofold approach: first, the political and operative push towards the adoption of the Health Level 7 (HL7) standard within single hospitals and, second, providing a technological infrastructure for data sharing based on interoperability specifications recognized at the regional level for messages transmitted from healthcare providers to the central domain. The adoption of such regional interoperability specifications enabled the communication among heterogeneous systems placed in different hospitals in Lombardy. Integrating the Healthcare Enterprise (IHE) integration profiles which refer to HL7 standards are adopted within hospitals for message exchange and for the definition of integration scenarios. The IHE patient administration management (PAM) profile with its different workflows is adopted for patient management, whereas the Scheduled Workflow (SWF), the Laboratory Testing Workflow (LTW), and the Ambulatory Testing Workflow (ATW) are adopted for order management. At present, the system manages 4,700,000 pharmacological e-prescriptions, and 1,700,000 e-prescriptions for laboratory exams per month. It produces, monthly, 490,000 laboratory medical reports, 180,000 radiology medical reports, 180

Russian and Belorussian firms receive CMS Gold Awards

CERN Multimedia

Maximilien Brice

2003-01-01

On 7 March, CMS handed out its three latest Gold Awards in recognition of outstanding supplier performance. Photos 01,02: Prof. Felicitas Pauss, Deputy Chair of the CMS Collaboration Board, presents a CMS Gold Award to Professor Valery Novikov, Director-General of Myasishchev Design Bureau, Zhukovsky, Moscow Region, Russia. The Myasishchev company was responsible for the carbon fibre structures in which the fragile lead tungstate crystals of the electromagnetic calorimeter end-caps are to be embedded. These lightweight structures must support a weight of 22.9 tonnes in each end-cap! The company produced a very thin-walled modular structure that ensured the calorimeter performance would not be harmed, while remaining stable and strong. Photos 03,04: Prof. Felicitas Pauss, Deputy Chair of the CMS Collaboration Board, presents a CMS Gold Award to Professor Boris Gabaraev, General director of N.A. Dollezhal Research and Development Institute of Power Engineering (NIKIET), Moscow, Russia (a.k.a. ENTEK) for the de...

Determination of the occurrence of gold in an unoxidized Carlin-type ore sample using synchrotron radiation

International Nuclear Information System (INIS)

Chen, J.R.; Chao, E.C.T.; Minkin, J.A.; Back, J.M.; Bagby, W.C.; Rivers, M.L.; Sutton, S.R.; Hanson, A.L.; Jones, K.W.

1986-01-01

The occurrence of the so-called invisible gold in two unoxidized Carlin-type gold samples from Nevada have been determined using synchrotron x-ray fluorescence (SXRF) analysis at the National Sychrotron Light Source, Brookhaven National Laboratory. The samples were a bedded sample from the east ore zone of the Carlin deposit and a breccia sample from Horse Canyon. Preliminary results show that gold is found only in the Horse Canyon breccia sample. Experimental details including other x-ray line and diffraction peak interferences, standards used, and minimum detection limits (MDLs) are discussed. Gold was not detected in euhedral pyrite crystals except in the interior porous portion of one grain with MDLs of 0.8 to 3 ppM. Gold was detected in some parts of the matrix. The phase which contains gold has not yet been identified. The highest content of gold so far analyzed is about 40 ppM. Implications of these new findings are discussed. 2 figs

The restoration of the gold standard after the US Civil War : A volatility analysis

NARCIS (Netherlands)

Meulemann, Max; Uebele, Martin; Wilfling, Bernd

This paper presents a new view on the gold price of greenbacks during and after the American Civil War by analyzing exchange-rate volatility rather than exchange-rate levels. Our empirical investigation detects regimes of high and low volatility alternating in a way that is consistent with a

A Sub-Microanalysis Approach in Chemical Characterisation of Gold Nanorods Formed by a Novel Polymer-Immobilised Gold Seeds Base

Directory of Open Access Journals (Sweden)

Majid Kazemian Abyaneh

2017-10-01

Full Text Available Gold nanorods (GNRs have been fabricated by a novel polymer-immobilised seed mediated method using ultraviolet (UV photoreduced gold-polymethylmethacrylate (Au–PMMA nanocomposites as a seed platform and characterised at sub-micron scale regime with synchrotron-based techniques; near-edge X-ray absorption fine structure (NEXAFS spectroscopy and X-ray fluorescence (XRF mapping. In this report, it is shown that investigating polymer nanocomposites using combination of XRF mapping and NEXAFS spectromicroscopy can help to see the growth phenomenon from different perspective than conventional characterisation techniques. XRF maps are used to explore distribution of the constituent elements and showing how polymer matrix making stripe patterns along with regions where GNRs are formed. NEXAFS carbon (C K-edge spectra have been taken at three different stages of synthesis: (1 on Au–PMMA nanocomposites before UV irradiation, (2 after gold nanoparticles formation, and (3 after GNRs formation. It reveals how polymer matrix has been degraded during GNRs formation and avoiding chemically or physically damage to polymer matrix is crucial to control the formation of GNRs.

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.

Prehospital Emergencies in Illegal Gold Mining Sites in French Guiana.

Science.gov (United States)

Egmann, Gérald; Tattevin, Pierre; Palancade, Renaud; Nacher, Matthieu

2018-03-01

Illegal gold mining is flourishing in French Guiana, existing outside the law due to both the high cost of gold mining permits and the challenges of law enforcement within the Amazon forest. We report the characteristics of, and the medical responses to, medical emergencies in illegal gold mining sites. We performed a retrospective study of all medical emergencies reported from illegal gold mining sites to the centralized call office of SAMU 973 from 1998 through 2000 and from 2008 through 2010. According to the national health care system, any medical emergency within the territory is handled by the prehospital emergency medical service (SAMU 973), irrespective of the patients' legal status. Data were extracted from the SAMU 973 notebook registry (1998-2000) or the SAMU 973 computerized database (2008-2010) and werre collected using a standardized questionnaire. Of 71,932 calls for medical emergencies in French Guiana during the study periods, 340 (0.5%) originated from illegal gold mining sites. Of these, 196 (58%) led to medical evacuation by helicopter, whereas the overall rate of evacuation by helicopter after placing a call to SAMU 973 was only 4% (3020/71,932; PAmazon forest mostly include infectious diseases, followed by trauma, and often require medical evacuation by helicopter. Our study suggests that implementation of preventive medicine within gold mining sites, irrespective of their legal status, could be cost-effective and reduce morbidity. Copyright © 2017 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

Stabilization of sputtered gold and silver nanoparticles in PEG colloid solutions

International Nuclear Information System (INIS)

Slepička, P.; Elashnikov, R.; Ulbrich, P.; Staszek, M.; Kolská, Z.; Švorčík, V.

2015-01-01

In this study, a simple technique for preparation of colloid solution of metal nanoparticles in polyethylene glycol (PEG)/H 2 O is described. By this technique, stable colloidal metal solutions can be prepared ready for use without application of chemical reactions, stabilizers, or reducing agents. The nanoparticles are created by direct sputtering of metal into PEG. The influence of sputter conditions and the concentration of PEG/H 2 O on the properties of nanoparticles was studied. The nanoparticles were characterized by transmission electron microscopy, atomic absorption spectrometry, dynamic light scattering, and UV–Vis spectroscopy. UV–Vis spectra of gold nanoparticle solution exhibit localized surface plasmon resonance characteristic peaks located in the region 513–560 nm (PEG/H 2 O—1/1), 509–535 nm (PEG/H 2 O—1/9), and for silver nanoparticles in the region from 401 to 421 nm. Silver nanoparticles have a broader size distribution compared with gold ones. An appropriate choice of concentration, mixing, and deposition conditions allows preparing the stable solution of gold or silver nanoparticles

Stabilization of sputtered gold and silver nanoparticles in PEG colloid solutions

Energy Technology Data Exchange (ETDEWEB)

Slepička, P., E-mail: petr.slepicka@vscht.cz; Elashnikov, R. [University of Chemistry and Technology Prague, Department of Solid State Engineering (Czech Republic); Ulbrich, P. [University of Chemistry and Technology Prague, Department of Biochemistry and Microbiology (Czech Republic); Staszek, M. [University of Chemistry and Technology Prague, Department of Solid State Engineering (Czech Republic); Kolská, Z. [University of J. E. Purkyně, Faculty of Science (Czech Republic); Švorčík, V. [University of Chemistry and Technology Prague, Department of Solid State Engineering (Czech Republic)

2015-01-15

In this study, a simple technique for preparation of colloid solution of metal nanoparticles in polyethylene glycol (PEG)/H{sub 2}O is described. By this technique, stable colloidal metal solutions can be prepared ready for use without application of chemical reactions, stabilizers, or reducing agents. The nanoparticles are created by direct sputtering of metal into PEG. The influence of sputter conditions and the concentration of PEG/H{sub 2}O on the properties of nanoparticles was studied. The nanoparticles were characterized by transmission electron microscopy, atomic absorption spectrometry, dynamic light scattering, and UV–Vis spectroscopy. UV–Vis spectra of gold nanoparticle solution exhibit localized surface plasmon resonance characteristic peaks located in the region 513–560 nm (PEG/H{sub 2}O—1/1), 509–535 nm (PEG/H{sub 2}O—1/9), and for silver nanoparticles in the region from 401 to 421 nm. Silver nanoparticles have a broader size distribution compared with gold ones. An appropriate choice of concentration, mixing, and deposition conditions allows preparing the stable solution of gold or silver nanoparticles.

Banana peel extract mediated synthesis of gold nanoparticles.

Science.gov (United States)

Bankar, Ashok; Joshi, Bhagyashree; Kumar, Ameeta Ravi; Zinjarde, Smita

2010-10-01

Gold nanoparticles were synthesized by using banana peel extract (BPE) as a simple, non-toxic, eco-friendly 'green material'. The boiled, crushed, acetone precipitated, air-dried peel powder was used to reduce chloroauric acid. A variety of nanoparticles were formed when the reaction conditions were altered with respect to pH, BPE content, chloroauric acid concentration and temperature of incubation. The reaction mixtures displayed vivid colors and UV-vis spectra characteristic of gold nanoparticles. Dynamic light scattering (DLS) studies revealed that the average size of the nanoparticles under standard synthetic conditions was around 300nm. Scanning electron microscopy and energy dispersive spectrometry (EDS) confirmed these results. A coffee ring phenomenon, led to the aggregation of the nanoparticles into microcubes and microwire networks towards the periphery of the air-dried samples. X-ray diffraction studies of the samples revealed spectra that were characteristic for gold. Fourier transform infra red (FTIR) spectroscopy indicated the involvement of carboxyl, amine and hydroxyl groups in the synthetic process. The BPE mediated nanoparticles displayed efficient antimicrobial activity towards most of the tested fungal and bacterial cultures.

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.

Analysis of gold and silver concentration on gold mining tailings by neutron activation analysis

International Nuclear Information System (INIS)

Sadikov, I.I.; Salimov, M.I.; Sadykova, Z.O.

2014-01-01

Full text: Instrumental neutron-activation analysis without radiochemical separation is one of most applicable and often used methods to analyze the concentration of gold, silver and other rare and noble metals in gold ores. This method is not suitable for analyzing low concentration of gold and silver in gold mining tailings due to rather high concentration of some elements. Samples are dissolved by boiling in a mixture of concentrated hydrochloric and nitric acids to extract gold and silver into the solution. Chemical yield of gold and silver after dissolution of the sample and further chromatographic separation is between 92 and 95 percent respectively

Gold nanoparticle formation in diamond-like carbon using two different methods: Gold ion implantation and co-deposition of gold and carbon

International Nuclear Information System (INIS)

Salvadori, M. C.; Teixeira, F. S.; Araújo, W. W. R.; Sgubin, L. G.; Cattani, M.; Spirin, R. E.; Brown, I. G.

2012-01-01

We describe work in which gold nanoparticles were formed in diamond-like carbon (DLC), thereby generating a Au-DLC nanocomposite. A high-quality, hydrogen-free DLC thin film was formed by filtered vacuum arc plasma deposition, into which gold nanoparticles were introduced using two different methods. The first method was gold ion implantation into the DLC film at a number of decreasing ion energies, distributing the gold over a controllable depth range within the DLC. The second method was co-deposition of gold and carbon, using two separate vacuum arc plasma guns with suitably interleaved repetitive pulsing. Transmission electron microscope images show that the size of the gold nanoparticles obtained by ion implantation is 3-5 nm. For the Au-DLC composite obtained by co-deposition, there were two different nanoparticle sizes, most about 2 nm with some 6-7 nm. Raman spectroscopy indicates that the implanted sample contains a smaller fraction of sp 3 bonding for the DLC, demonstrating that some sp 3 bonds are destroyed by the gold implantation.

Fire-assay determination of small amounts of gold in mineral raw materials

International Nuclear Information System (INIS)

Kuligin, V.M.; Zdorova, Eh.P.; Popova, N.N.; Rakovskij, Eh.V.

1976-01-01

Gold is concentrated in 0.1-1.0 g of a lead alloy obtained in fire assay and cupellation and can be used for the analysis of a number of geological samples. The procedure makes it possible to determine gold with a limit of detection of 0.02 g/ton from a representative sample of 50-100 g. The use of lead acetate ensures the limit of detection of 0.002 g/ton, the relative standard deviation being greater than 0.01

Gold grade of epithermal gold ore at Lamuntet, Brang Rea, West Sumbawa District, West Nusa Tenggara Province, Indonesia

Science.gov (United States)

Ernawati, Rika; Idrus, Arifudin; TBMP, Himawan

2017-06-01

Lamuntet is one of gold ore mining area carried out by the Artisanal Small scale Gold Mining (ASGM) located in West Sumbawa, Indonesia. Most of the miners at this area are not the local miners but also those from other regions. Mineralization of this area is strong identified as low sulfidation epithermal system. There are two blocks of this mining location, namely, Ngelampar block with an area of 0.164 km2 and Song block with an area of 0.067 km2. This study was focused on Ngelampar block. The characteristic of epithermal system is the existence of quartz vein with comb, vuggy, and sugary texture. The aim of this research was to analyze the gold grade and other metals, such as Cu, Ag, Pb, As, Zn, and Hg. The research methods included literature study from previous researches, field work, laboratory work, and interpretation. The literature study was performed on previous researches with similar study area. The field work comprised of direct observation and sampling. Fieldwork was done for a week to obtain gold ore/vein. Sixteen samples were analyzed to obtain the grade of ore/metal. The Hg laboratory analysis was then performed on the six samples with the highest gold grade. Laboratory works were conducted at Intertek Jakarta by using Fire Assay (FA) for gold grade and Atomic Absorption Spectrophotometry (AAS) for Cu, Ag, Pb, As, Zn, and Hg. Results of the analysis showed the range of Au was grade (0.1 ppm - 27.8 ppm), Cu was 26 ppm -1740 ppm, Pb was 101 ppm- >4000 ppm, Zn of 73 ppm- >10,000 ppm, Ag of 3 ppm -185 ppm, As was 150 ppm-6530 ppm, and Hg of 0.08 ppm - 1.89 ppm. L1 and L15 had high grade for all values (Au, Ag, Zn, Cu, As, and Hg). Gold mineralization was formed as electrum because of Ag content is higher than 20%. Associated minerals of the samples in the study area were galena, sphalerite, arsenopyrite, and chalcopyrite which showed the characteristic of rich base metal of Pb, Zn, and Cu at LS epithermal.

The Process of People Gold Mining in Paningkaban Village Banyumas Indonesia

Directory of Open Access Journals (Sweden)

Muslihudin Muslihudin

2018-01-01

Full Text Available Gold mining in Paningkaban Banyumas conducted by the community is called the People gold mining. At the beginning, many miners from outside the region have involved and transferred of method, technic and knowledge about gold mining to local people. The aim of the study is to identify the existing process of public gold mining. The method of the study is qualitative by using observation and interview. The result showed that the mining process are: 1. Determining the location of mining well; in this determination there are two references; rational and intuition 2. Mining; at this stage, a deep well is drawn about 50-100 meters that leads vertically and horizontally. It is the most high-risk stage because of work accidents that occurred and potentially environment destruction. 3. Pulverization; this stage is classified as the lowest level of difficulty and risk, therefore in this work many woman included. 4. Rolling; in this stage involves enough technology, electrical mechanic and energy with the dynamo and using mercury that potentially contaminate environment. 5. Filtering; this stage is a quite risky because the workers contact directly with mercury. 6. Burning; is the shortest process to separate mercury with gold grains. 7. Sales to local buyer guided by the international gold market in every Thursday.

The Process of People Gold Mining in Paningkaban Village Banyumas Indonesia

Science.gov (United States)

Muslihudin; Bambang, Azis Nur; Hendarto, Eko; Putranto, Thomas Triadi

2018-02-01

Gold mining in Paningkaban Banyumas conducted by the community is called the People gold mining. At the beginning, many miners from outside the region have involved and transferred of method, technic and knowledge about gold mining to local people. The aim of the study is to identify the existing process of public gold mining. The method of the study is qualitative by using observation and interview. The result showed that the mining process are: 1. Determining the location of mining well; in this determination there are two references; rational and intuition 2. Mining; at this stage, a deep well is drawn about 50-100 meters that leads vertically and horizontally. It is the most high-risk stage because of work accidents that occurred and potentially environment destruction. 3. Pulverization; this stage is classified as the lowest level of difficulty and risk, therefore in this work many woman included. 4. Rolling; in this stage involves enough technology, electrical mechanic and energy with the dynamo and using mercury that potentially contaminate environment. 5. Filtering; this stage is a quite risky because the workers contact directly with mercury. 6. Burning; is the shortest process to separate mercury with gold grains. 7. Sales to local buyer guided by the international gold market in every Thursday.

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.

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

International Nuclear Information System (INIS)

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

2012-01-01

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.

Immense random colocalization, revealed by automated high content image cytometry, seriously questions FISH as gold standard for detecting EML4-ALK fusion.

Science.gov (United States)

Smuk, Gábor; Tornóczky, Tamás; Pajor, László; Chudoba, Ilse; Kajtár, Béla; Sárosi, Veronika; Pajor, Gábor

2018-05-19

EML4-ALK gene fusion (inv2(p21p23)) of non-small cell lung cancer (NSCLC) predisposes to tyrosine kinase inhibitor treatment. One of the gold standard diagnostics is the dual color (DC) break-apart (BA) FISH technique, however, the unusual closeness of the involved genes has been suggested to raise likelihood of random co-localization (RCL) of signals. Although this is suspected to decrease sensitivity (often to as low as 40-70%), the exact level and effect of RCL has not been revealed thus far. Signal distances were analyzed to the 0.1 µm precision in more than 25,000 nuclei, via automated high content-image cytometry. Negative and positive controls were created using conventional DC BA-, and inv2(p21p23) mimicking probe-sets, respectively. Average distance between red and green signals was 9.72 pixels (px) (±5.14px) and 3.28px (±2.44px), in positives and negatives, respectively; overlap in distribution being 41%. Specificity and sensitivity of correctly determining ALK status was 97% and 29%, respectively. When investigating inv2(p21p23) with DC BA FISH, specificity is high, but seven out of ten aberrant nuclei are inevitably falsely classified as negative, due to the extreme level of RCL. Together with genetic heterogeneity and dilution effect of non-tumor cells in NSCLC, this immense analytical false negativity is the primary cause behind the often described low diagnostic sensitivity. These results convincingly suggest that if FISH is to remain a gold standard for detecting the therapy relevant inv(2), either a modified evaluation protocol, or a more reliable probe-design should be considered than the current DC BA one. © 2018 International Society for Advancement of Cytometry. © 2018 International Society for Advancement of Cytometry.

Performances of Four Helicobacter pylori Serological Detection Kits Using Stool Antigen Test as Gold Standard.

Directory of Open Access Journals (Sweden)

Susheela D Biranjia-Hurdoyal

Full Text Available The aim was to determine the performances of four Helicobacter pylori serological detection kits in different target groups, using Amplified IDEIA™ Hp StAR™ as gold standard. Kits studied were Rapid Immunochromatoghraphic Hexagon, Helicoblot 2.1, an EIA IgG kit and EIA IgA kit.Stool and blood samples were collected from 162 apparently healthy participants (control and 60 Type 2 diabetes mellitus (T2DM patients.The performances of the four serological detection kits were found to be affected by gender, age, health status and ethnicity of the participants. In the control group, the Helicoblot 2.1 kit had the best performance (AUC = 0.85; p<0.05, accuracy = 86.4%, followed by EIA IgG (AUC = 0.75; p<0.05, accuracy = 75.2%. The Rapid Hexagon and EIA IgA kits had relatively poor performances. In the T2DM subgroup, the kits H2.1 and EIA IgG had best performances, with accuracies of 96.5% and 93.1% respectively. The performance of EIA IgG improved with adjustment of its cut-off value.The performances of the detection kits were affected by various factors which should be taken into consideration.

The Yatela gold deposit in Mali, West Africa: The final product of a long-lived history of hydrothermal alteration and weathering

Science.gov (United States)

Masurel, Quentin; Miller, John; Hein, Kim A. A.; Hanssen, Eric; Thébaud, Nicolas; Ulrich, Stanislav; Kaisin, Jean; Tessougue, Samuel

2016-01-01

The Yatela gold deposit is located in the Kédougou-Kénieba inlier (KKI), a window of ca. 2200-2050 Ma rocks that are exposed in eastern Senegal and western Mali. The geology of the KKI differs from other Paleoproterozoic granite-greenstone belts and sedimentary basins by the abundance of carbonate rocks. The Yatela deposit occurs within 8 km of the regional-scale Senegal-Mali Shear Zone. Country rocks in the Yatela region have been subjected to polycyclic deformation and regional greenschist-facies metamorphism. A syn-kinematic diorite stock has intruded the metasedimentary sequences in the open pit and is associated with a hornblende-hornfels contact aureole. Field relationships and micro-textural data indicate that the primary gold mineralisation is shear-hosted. The similar relative timing and structural setting between the Yatela primary gold mineralisation and other world-class deposits in the region (e.g., Loulo, Lawrence et al., 2013a; Massawa, Treloar et al., 2014; Sadiola Hill, Masurel et al., in press) suggest that regional orogenic gold mineralisation occurred during a period of transcurrent tectonics, after the cessation of regional compressional deformation. The primary gold mineralisation at Yatela, however, is low-grade and sub-economic. It is hosted by marbles and, to a lesser extent, diorite. The primary ore is pyrite-rich, with abundant chalcopyrite, minor arsenopyrite and accessory Zn-Pb-Sb-Fe-Ag-Co-Ni-bearing mineral species. Post-Birimian surficial dissolution of hydrothermally altered and mineralised host marbles resulted in the creation of troughs, which were draped and infilled with a ferruginous dissolution residue enriched in gold. This auriferous residuum formed the economic resource mined at Yatela until decommissioning in 2013. The Yatela gold deposit is unique with respect to mineralisation types encountered in West Africa because an auriferous residuum of economic interest (>1 Moz) derives from an underlying sub-economic Birimian

Global demand for gold is another threat for tropical forests

International Nuclear Information System (INIS)

Alvarez-Berríos, Nora L; Mitchell Aide, T

2015-01-01

The current global gold rush, driven by increasing consumption in developing countries and uncertainty in financial markets, is an increasing threat for tropical ecosystems. Gold mining causes significant alteration to the environment, yet mining is often overlooked in deforestation analyses because it occupies relatively small areas. As a result, we lack a comprehensive assessment of the spatial extent of gold mining impacts on tropical forests. In this study, we provide a regional assessment of gold mining deforestation in the tropical moist forest biome of South America. Specifically, we analyzed the patterns of forest change in gold mining sites between 2001 and 2013, and evaluated the proximity of gold mining deforestation to protected areas (PAs). The forest cover maps were produced using the Land Mapper web application and images from the MODIS satellite MOD13Q1 vegetation indices 250 m product. Annual maps of forest cover were used to model the incremental change in forest in ∼1600 potential gold mining sites between 2001–2006 and 2007–2013. Approximately 1680 km 2 of tropical moist forest was lost in these mining sites between 2001 and 2013. Deforestation was significantly higher during the 2007–2013 period, and this was associated with the increase in global demand for gold after the international financial crisis. More than 90% of the deforestation occurred in four major hotspots: Guianan moist forest ecoregion (41%), Southwest Amazon moist forest ecoregion (28%), Tapajós–Xingú moist forest ecoregion (11%), and Magdalena Valley montane forest and Magdalena–Urabá moist forest ecoregions (9%). In addition, some of the more active zones of gold mining deforestation occurred inside or within 10 km of ∼32 PAs. There is an urgent need to understand the ecological and social impacts of gold mining because it is an important cause of deforestation in the most remote forests in South America, and the impacts, particularly in aquatic systems

Moving metal artifact reduction in cone-beam CT scans with implanted cylindrical gold markers

International Nuclear Information System (INIS)

Toftegaard, Jakob; Fledelius, Walther; Worm, Esben S.; Poulsen, Per R.; Seghers, Dieter; Huber, Michael; Brehm, Marcus; Elstrøm, Ulrik V.

2014-01-01

Purpose: Implanted gold markers for image-guided radiotherapy lead to streaking artifacts in cone-beam CT (CBCT) scans. Several methods for metal artifact reduction (MAR) have been published, but they all fail in scans with large motion. Here the authors propose and investigate a method for automatic moving metal artifact reduction (MMAR) in CBCT scans with cylindrical gold markers. Methods: The MMAR CBCT reconstruction method has six steps. (1) Automatic segmentation of the cylindrical markers in the CBCT projections. (2) Removal of each marker in the projections by replacing the pixels within a masked area with interpolated values. (3) Reconstruction of a marker-free CBCT volume from the manipulated CBCT projections. (4) Reconstruction of a standard CBCT volume with metal artifacts from the original CBCT projections. (5) Estimation of the three-dimensional (3D) trajectory during CBCT acquisition for each marker based on the segmentation in Step 1, and identification of the smallest ellipsoidal volume that encompasses 95% of the visited 3D positions. (6) Generation of the final MMAR CBCT reconstruction from the marker-free CBCT volume of Step 3 by replacing the voxels in the 95% ellipsoid with the corresponding voxels of the standard CBCT volume of Step 4. The MMAR reconstruction was performed retrospectively using a half-fan CBCT scan for 29 consecutive stereotactic body radiation therapy patients with 2–3 gold markers implanted in the liver. The metal artifacts of the MMAR reconstructions were scored and compared with a standard MAR reconstruction by counting the streaks and by calculating the standard deviation of the Hounsfield units in a region around each marker. Results: The markers were found with the same autosegmentation settings in 27 CBCT scans, while two scans needed slightly changed settings to find all markers automatically in Step 1 of the MMAR method. MMAR resulted in 15 scans with no streaking artifacts, 11 scans with 1–4 streaks, and 3 scans

Phanerozoic continental growth and gold metallogeny of Asia

Science.gov (United States)

Goldfarb, Richard J.; Taylor, Ryan D.; Collins, Gregory S.; Goryachev, Nicolay A.; Orlandini, Omero Felipe

2014-01-01

The Asian continent formed during the past 800 m.y. during late Neoproterozoic through Jurassic closure of the Tethyan ocean basins, followed by late Mesozoic circum-Pacific and Cenozoic Himalayan orogenies. The oldest gold deposits in Asia reflect accretionary events along the margins of the Siberia, Kazakhstan, North China, Tarim–Karakum, South China, and Indochina Precambrian blocks while they were isolated within the Paleotethys and surrounding Panthalassa Oceans. Orogenic gold deposits are associated with large-scale, terrane-bounding fault systems and broad areas of deformation that existed along many of the active margins of the Precambrian blocks. Deposits typically formed during regional transpressional to transtensional events immediately after to as much as 100 m.y. subsequent to the onset of accretion or collision. Major orogenic gold provinces associated with this growth of the Asian continental mass include: (1) the ca. 750 Ma Yenisei Ridge, ca. 500 Ma East Sayan, and ca. 450–350 Ma Patom provinces along the southern margins of the Siberia craton; (2) the 450 Ma Charsk belt of north-central Kazakhstan; (3) the 310–280 Ma Kalba belt of NE Kazakhstan, extending into adjacent NW Xinjiang, along the Siberia–Kazakhstan suture; (4) the ca. 300–280 Ma deposits within the Central Asian southern and middle Tien Shan (e.g., Kumtor, Zarmitan, Muruntau), marking the closure of the Turkestan Ocean between Kazakhstan and the Tarim–Karakum block; (5) the ca. 190–125 Ma Transbaikal deposits along the site of Permian to Late Jurassic diachronous closure of the Mongol–Okhotsk Ocean between Siberia and Mongolia/North China; (6) the probable Late Silurian–Early Devonian Jiagnan belt formed along the margin of Gondwana at the site of collision between the Yangtze and Cathaysia blocks; (7) Triassic deposits of the Paleozoic Qilian Shan and West Qinling orogens along the SW margin of the North China block developed during collision of South China

Determination of gold in natural waters by neutron activation-#betta#-spectrometry after preconcentration on activated charcoal

International Nuclear Information System (INIS)

Hamilton, T.W.; Ellis, J.; Florence, T.M.

1983-01-01

A method for the determination of gold at very low levels in waters is presented. The method involves batchwise pre-concentration of gold from 1 l of water at pH 3-4 onto 0.1 g of activated charcoal by shaking for 5 min and subsequent treatment of the activated charcoal by instrumental neutron activation-#betta#-spectrometry. Activated charcoal quantitatively adsorbs ionic and colloidal gold from solutions prepared with distilled water and also from natural surface waters spiked and equilibrated with these two forms of gold. Three ion-exchange resins were evaluated for pre-concentration purposes; ionic gold removal was quantitative but colloidal gold removal was incomplete. Electrodeposition at a carbon fibre electrode gave similar results. The charcoal pre-concentration technique was tested on solutions containing 198 Au tracer and a total gold concentration of 1 μg l - 1 . The limit of detection of total gold (ionic and colloidal) for the carbon adsorption/neutron activation-#betta#-spectrometry procedure is 0.3 ng l - 1 . The method was used to determine gold in surface waters from auriferous regions. (Auth.)

THE CYANIDE LEACH TECHNOLOGY IN GOLD AND SILVER MINING HARMFUL EFFECTS AND SUGGESTIONS FOR REMEDYING

OpenAIRE

Judit PETRES

2013-01-01

The region named Roşia Montană became famous due to its rich mineral resources. The most precious treasure which has been found is the gold. A state-run gold mine functioned for many years and the continuous pollution due to the gold extraction became very dangerous. All these cyanide-containing waste are hazardous to wildlife, natural resources and human health if not properly managed. The consequences of cyanide hazards may be devastating, sometimes killing everything for several miles down...

For the love of gold

International Nuclear Information System (INIS)

Young, J.E.

1993-01-01

Gold is found in minute quantities and gold mining generates enormous amounts of waste materials and long history of environmental destruction: mercury in tailing, eroded land, and acid mine drainage are legacies of the past. The problem has become worse in recent years in North America, Australia, the Amazon basin, Philippines. This paper describes the economics of gold and the changes in the world economy which has precipitated the new gold rushes. Current technology uses a cyanide solution for leaching small amounts of gold from tons of waste, and mercury remains a toxic waste of gold mining. Both short and long term results of gold mining, on the environment and on indiginous populations are described

THE CYANIDE LEACH TECHNOLOGY IN GOLD AND SILVER MINING HARMFUL EFFECTS AND SUGGESTIONS FOR REMEDYING

Directory of Open Access Journals (Sweden)

Judit PETRES

2013-11-01

Full Text Available The region named Roşia Montană became famous due to its rich mineral resources. The most precious treasure which has been found is the gold. A state-run gold mine functioned for many years and the continuous pollution due to the gold extraction became very dangerous. All these cyanide-containing waste are hazardous to wildlife, natural resources and human health if not properly managed. The consequences of cyanide hazards may be devastating, sometimes killing everything for several miles downstream. It has not yet been found a way of both taking advantages of the economic benefits of gold and maintaining a liveable habitat.

Frontiers in Gold Chemistry

OpenAIRE

Ahmed A. Mohamed

2015-01-01

Basic chemistry of gold tells us that it can bond to sulfur, phosphorous, nitrogen, and oxygen donor ligands. The Frontiers in Gold Chemistry Special Issue covers gold complexes bonded to the different donors and their fascinating applications. This issue covers both basic chemistry studies of gold complexes and their contemporary applications in medicine, materials chemistry, and optical sensors. There is a strong belief that aurophilicity plays a major role in the unending applications of g...

Sediment-hosted gold deposits of the world: database and grade and tonnage models

Science.gov (United States)

Berger, Vladimir I.; Mosier, Dan L.; Bliss, James D.; Moring, Barry C.

2014-01-01

recommend using the appropriate grade and tonnage model presented in this study for mineral resource assessments depending on the geologic and mineralogical data available for a region. Tonnage and contained gold within the general sediment-hosted gold model are analyzed based on major geologic features such as tectonic setting and magmatic (dikes, sills, and stocks) or amagmatic environment. The results show a significant difference in tonnage and contained gold, with higher median values in deposits spatially associated with igneous rocks, regardless of structural style of the deposit. These results suggest that magmatic environments control mineralization intensity—an important consideration in the regional assessment of prospective areas for sediment-hosted gold deposits.

Non-standard patch test

Directory of Open Access Journals (Sweden)

Astri Adelia

2018-06-01

Full Text Available In managing contact dermatitis, identification of the causative agent is essential to prevent recurrent complaints. Patch test is the gold standard to identify the causative agent. Nowadays, there are many patch test standard materials available in the market, but do not include all the materials that potentially cause contact dermatitis. Patch test using patient’s own products or later we refer to as non-standard materials, is very helpful in identifying the causative agents of contact dermatitis. Guidance is needed in producing non-standard patch test materials in order to avoid test results discrepancy.

Gold removal rate by ion sputtering as a function of ion-beam voltage and raster size using Auger electron spectroscopy. Final report

International Nuclear Information System (INIS)

Boehning, C.W.

1983-01-01

Gold removal rate was measured as a function of ion beam voltage and raster size using Auger electron spectroscopy (AES). Three different gold thicknesses were developed as standards. Two sputter rate calibration curves were generated by which gold sputter rate could be determined for variations in ion beam voltage or raster size

Transvaginal duplex ultrasonography appears to be the gold standard investigation for the haemodynamic evaluation of pelvic venous reflux in the ovarian and internal iliac veins in women.

Science.gov (United States)

Whiteley, M S; Dos Santos, S J; Harrison, C C; Holdstock, J M; Lopez, A J

2015-12-01

To assess the suitability of transvaginal duplex ultrasonography to identify pathological reflux in the ovarian and internal iliac veins in women. A retrospective study of patients treated in 2011 and 2012 was performed in a specialised vein clinic. Diagnostic transvaginal duplex ultrasonography in women presenting with symptoms or signs of pelvic vein reflux were compared with the outcomes of treatment from pelvic vein embolisation. A repeat transvaginal duplex ultrasonography was performed 6 weeks later by a blinded observer and any residual reflux was identified. Results from 100 sequential patients were analysed. Mean age 44.2 years (32-69) with mode average parity of 3 (0-5 deliveries). Pre-treatment, 289/400 veins were refluxing (ovarian - 29 right, 81 left; internal iliac - 93 right, 86 left). Coil embolisation was successful in 86/100 patients and failed partially in 14/100 - 5 due to failure to cannulate the target vein. One false-positive diagnosis was made. Currently there is no accepted gold standard for pelvic vein incompetence. Comparing transvaginal duplex ultrasonography with the outcome from selectively treating the veins identified as having pathological reflux with coil embolisation, there were no false-negative diagnoses and only one false-positive. This study suggests that transvaginal duplex ultrasonography could be the gold standard in assessing pelvic vein reflux. © The Author(s) 2014.

Discriminating between absorption and scattering coefficients in optical characterisation measurements on gold nanoparticle based photoacoustic contrast agents

NARCIS (Netherlands)

Ungureanu, C.; Manohar, Srirang; van Leeuwen, Ton; Amelink, A.; Sterenborg, Henricus J.C.M.; Oraevsky, Alexander A.; Wang, Lihong V.

2009-01-01

Plasmon resonant nanoparticles such as gold nanoshells and gold nanorods can be tuned to possess sharp interaction peaks in the near-infrared wavelength regions. These have great importance as contrast agents in photoacoustic imaging and as photothermal agents for therapeutic applications due to

Gold clusters sliding on graphite: a possible quartz crystal microbalance experiment?

International Nuclear Information System (INIS)

Pisov, S; Tosatti, E; Tartaglino, U; Vanossi, A

2007-01-01

A large measured two-dimensional (2D) diffusion coefficient of gold nanoclusters on graphite has been known experimentally and theoretically for about a decade. When subjected to a lateral force, these clusters should slide with an amount of friction that can be measured. We examine the hypothetical possibility of measuring by quartz crystal microbalance (QCM) the phononic sliding friction of gold clusters in the size range around 250 atoms on a graphite substrate between 300 and 600 K. Assuming the validity of Einstein's relations of ordinary Brownian motion and making use of the experimentally available activated behaviour of the diffusion coefficients, we can predict the sliding friction and slip times as a function of temperature. It is found that a prototypical deposited gold cluster could yield slip times at the standard measurable size of 10 -9 s for temperatures around 450-500 K, or 200 0 C. Since gold nanoclusters may also melt at around these temperatures, QCM could offer the additional chance of observing this phenomenon through a frictional change

The Genomes OnLine Database (GOLD) v.5: a metadata management system based on a four level (meta)genome project classification

Science.gov (United States)

Reddy, T.B.K.; Thomas, Alex D.; Stamatis, Dimitri; Bertsch, Jon; Isbandi, Michelle; Jansson, Jakob; Mallajosyula, Jyothi; Pagani, Ioanna; Lobos, Elizabeth A.; Kyrpides, Nikos C.

2015-01-01

The Genomes OnLine Database (GOLD; http://www.genomesonline.org) is a comprehensive online resource to catalog and monitor genetic studies worldwide. GOLD provides up-to-date status on complete and ongoing sequencing projects along with a broad array of curated metadata. Here we report version 5 (v.5) of the database. The newly designed database schema and web user interface supports several new features including the implementation of a four level (meta)genome project classification system and a simplified intuitive web interface to access reports and launch search tools. The database currently hosts information for about 19 200 studies, 56 000 Biosamples, 56 000 sequencing projects and 39 400 analysis projects. More than just a catalog of worldwide genome projects, GOLD is a manually curated, quality-controlled metadata warehouse. The problems encountered in integrating disparate and varying quality data into GOLD are briefly highlighted. GOLD fully supports and follows the Genomic Standards Consortium (GSC) Minimum Information standards. PMID:25348402

The Genomes OnLine Database (GOLD) v.5: a metadata management system based on a four level (meta)genome project classification

Energy Technology Data Exchange (ETDEWEB)

Reddy, Tatiparthi B. K. [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Thomas, Alex D. [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Stamatis, Dimitri [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Bertsch, Jon [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Isbandi, Michelle [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Jansson, Jakob [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Mallajosyula, Jyothi [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Pagani, Ioanna [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Lobos, Elizabeth A. [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Kyrpides, Nikos C. [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); King Abdulaziz Univ., Jeddah (Saudi Arabia)

2014-10-27

The Genomes OnLine Database (GOLD; http://www.genomesonline.org) is a comprehensive online resource to catalog and monitor genetic studies worldwide. GOLD provides up-to-date status on complete and ongoing sequencing projects along with a broad array of curated metadata. Within this paper, we report version 5 (v.5) of the database. The newly designed database schema and web user interface supports several new features including the implementation of a four level (meta)genome project classification system and a simplified intuitive web interface to access reports and launch search tools. The database currently hosts information for about 19 200 studies, 56 000 Biosamples, 56 000 sequencing projects and 39 400 analysis projects. More than just a catalog of worldwide genome projects, GOLD is a manually curated, quality-controlled metadata warehouse. The problems encountered in integrating disparate and varying quality data into GOLD are briefly highlighted. Lastly, GOLD fully supports and follows the Genomic Standards Consortium (GSC) Minimum Information standards.

The NASA GOLD Mission: Exploring the Interface between Earth and Space

Science.gov (United States)

Mason, T.; Costanza, B.

2017-12-01

NASA's Global-scale Observations of the Limb and Disk, or GOLD, mission will explore a little understood area close to home, but historically hard to observe: the interface between Earth and space, a dynamic area of near-Earth space that responds both to space weather above, and the lower atmosphere below. GOLD, scheduled to launch into geostationary orbit in early 2018, will collect observations with a 30-minute cadence, much higher than any mission that has come before it. This will enable GOLD to be the first mission to study the day-to-day weather of a region of space—the thermosphere and ionosphere—rather than its long-term climate. GOLD will explore the near-Earth space environment, which is home to astronauts, radio signals used to guide airplanes and ships, and satellites that provide our communications and GPS systems. GOLD's unprecedented images and data will enable research that can improve situational awareness to help protect astronauts, spacecraft, and humans on the ground. As part of the GOLD communications and outreach program, the Office of Communications & Outreach at the Laboratory for Atmospheric and Space Physics (LASP) is developing a suite of products and programs to introduce the science of the GOLD mission to a broad range of public audiences, including students, teachers, journalists, social media practitioners, and the wider planetary and Earth science communities. We plan to showcase with this poster some of the tools we are developing to achieve this goal.

Delineation of Gold Mineralization Zone using Resistivity and Very Low Frequency Electromagnetic Methods around, North Singhbhum Mobile Belt, India.

Science.gov (United States)

Upadhyay, A.; Panda, K. P.; Singh, A.; Sharma, S. P.

2017-12-01

The results of electrical resistivity and VLF electromagnetic surveys are presented in this study to delineate the suitable geological structure associated with gold mineralization near Lawa Village (Seraikela-Kharsawan, Jharkhand), India. The area under observation lies in North Singhbhum Mobile Belt (NSMB) which is bounded by Chotanagpur Gneiss Complex in north and Archean Singhbhum Craton in the south. Shear zone of the study area, trending E-W, is mainly associated with Cu-U mineralization which is also associated with gold. Previous geological studies have revealed that this region can be a potential site for gold prospects within NSMB. A comprehensive electrical resistivity imaging and very low frequency surveys have been performed around Lawa village to outline appropriate conducting zones, with their lateral extension and depth extent, which may be associated with gold mineralization. Resistivity survey done using Dipole-Dipole multi-electrode array reveals multiple zones of mineralization separated by variable distances. The VLF data in the current study was tainted by non-stationary and non-linear noises which cannot be eliminated by standard filtering techniques. Therefore to restore signals with significant geologic information empirical mode decomposition (EMD) technique was used. The noise free data obtained was then processed using Fast Imaging technique to obtain apparent current density pseudo-sections for interpretation. Interpretation and analysis of results from each investigating survey demonstrate a steeply dipping conductor with E-W strike direction along the shear zone. These conductive zones are characterized by low resistivity and high current density values.

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.

Temperature-dependent surface density of alkylthiol monolayers on gold nanocrystals

Science.gov (United States)

Liu, Xuepeng; Lu, Pin; Zhai, Hua; Wu, Yucheng

2018-03-01

Atomistic molecular dynamics (MD) simulations are performed to study the surface density of passivating monolayers of alkylthiol chains on gold nanocrystals at temperatures ranging from 1 to 800 K. The results show that the surface density of alkylthiol monolayer reaches a maximum value at near room temperature (200-300 K), while significantly decreases with increasing temperature in the higher temperature region (> 300 {{K}}), and slightly decreases with decreasing temperature at low temperature (< 200 {{K}}). We find that the temperature dependence of surface ligand density in the higher temperature region is attributed to the substantial ligand desorption induced by the thermal fluctuation, while that at low temperature results from the reduction in entropy caused by the change in the ordering of passivating monolayer. These results are expected helpful to understand the temperature-dependent surface coverage of gold nanocrystals.

Moessbauerspectroscopy on Gold Ruby Glass

International Nuclear Information System (INIS)

Haslbeck, S.

2005-01-01

In this thesis, the chemical states of gold and the physical mechanisms of the growing process of the particles under the influence of additional ingredients like tin, lead, antimony and selenium before, during and after the colouring process are investigated by using the Moessbauer spectroscopy on 197 Au, 119 Sn and 121 Sb, optical spectroscopy and X-ray-diffraction. Gold in an unnealed, colourless state of the glasses consists of monovalent forming linear bonds to two neighbouring oxygen atoms. The Lamb-Moessbauer factor of these gold oxide bondings is observed as 0.095 at 4.2 K. The gold in it's oxide state transforms to gold particles with a diameter of 3 nm to 60 nm. The size of the gold particles is quite definable within the optical spectra and certain sizes are also discernable within the Moessbauer spectra. One component of the Moessbauer spectra is assigned to the surface layer of the gold particles. By comparing this surface component with the amount of the bulk metallic core, one can calculate the size of the gold particles. In the Moessbauer spectra of the colourless glass one also can find parts of bulk metallic gold. Investigations with X-ray diffraction show that these are gold particles with a diameter of 100 nm to 300 nm and therefore have no additional colouring effect within the visible spectrum. The Moessbauer spectra on gold of the remelt glasses are similar to those which have been measured on the initial colourless glasses

Aluminium-gold reference material for the k0-standardisation of neutron activation analysis

International Nuclear Information System (INIS)

Ingelbrecht, C.; Peetermans, F.; Corte, F. de; Wispelaere, A. de; Vandecasteele, C.; Courtijn, E.; Hondt, P. d'

1991-01-01

Gold is an excellent comparator material for the k 0 -standardisation of neutron activation analysis because of its convenient and well defined nuclear properties. The most suitable form for a reference material is a dilute aluminium-gold alloy, for which the self-shielding effect for neutrons is small. Castings of composition Al-0.1 wt.% Au were prepared by crucible-less levitation melting, which gives close control of ingot composition with minimal contamination of the melt. The alloy composition was checked using induction-coupled plasma source emission spectrometry. The homogeneity of the alloy was measured by neutron activation analysis and a relative standard deviation of the gold content of 0.30% was found (10 mg samples). Metallography revealed a homogeneous distribution of AuAl 2 particles. The alloy was certified as Reference Materials CBNM-530, with certified gold mass fraction 0.100±0.002 wt.%. (orig.)

[Gold salt alveolitis in 3 patients with rheumatoid arthritis].

Science.gov (United States)

Music, E; Tomsic, M; Logar, D

1995-06-01

When the characteristic symptoms for an interstitial pulmonary disease arise in patients with rheumatoid arthritis, a drug-induced alveolitis should be considered in the differential diagnosis. In such cases, the administration of the drug and gold salts should be stopped. The cases of three patients with rheumatoid arthritis (RA) who had been treated with gold salts for 2 months (A), 23 months (B), and 36 months (C) are presented. The total dose of sodium aureothiomalate amounted to 280 mg for patient A, 1150 mg for patient B, and 2190 mg for patient C. Clinical signs, X-rays of the lungs, pulmonary function tests, and laboratory tests were evaluated for the three patients while, for patient A BAL as well as provocation tests were additionally performed before and after therapy. In this case, the histological picture of the lungs is presented; biopsies were taken during the first BAL. The clinical complaints of all 3 patients were similar, with the alveolitis being observed as diffuse in one case and above all in the upper regions in two cases on radiology. This led to differing degrees of diffusion disorders in the lungs. In patient A, the diagnosis was made in the stage of progressive fibrotic alveolitis and was treated with D-penicillamine. All 3 patients received steroids over 3-6 months and the gold salts were stopped. Because of the long duration and doubtful differential diagnosis for patient A with either rheumatoid lung or gold salt alveolitis, a provocation test with sodium aureothiomalate was performed. All 3 patients had blood eosinophilia while, in case A, a thrombopenia was also found. A gold salt alveolitis can occur as a side effect of gold salts in addition to skin vasculitis and hematological disorders. When the gold salt administration is not stopped a fibrotic alveolitis can develop. The provocation test can be diagnostically useful to distinguish between a rheumatoid lung and gold salt alveolitis.

Gold, uranium and thorium in zones of greenschist displacement metamorphism

International Nuclear Information System (INIS)

Gavrilenko, B.V.; Savitskij, A.V.; Titov, V.V.

1987-01-01

Distribution of gold, uranium (bar and mobile) and thorium in 15 zones of greenschist dislocated metamorphism in different structures of the Karelo-Kola region carried out by geologic formations of the Early-Archean-Late-Proterozoic age has been studied. More than 200 samples of well core from 0-200 m depths have been analyzed. The results obtained testify to the increase of gold, uranium and less thorium content in zones of green-schist dislocated metamorphism in comparison with the enclosing rocks 1.4-3.1 times. The variation coefficient of gold, uranium and thorium content in green-schist dislocated tectonites increases 1.5-2.9 times. The correlation coefficient of Au/U mob. pair is +0.69, and Au/U bar pair -+0.87. Essential correlation between concentrations of all three elements in enclosing rocks is absent

Immunological properties of gold nanoparticles.

Science.gov (United States)

Dykman, Lev A; Khlebtsov, Nikolai G

2017-03-01

In the past decade, gold nanoparticles have attracted strong interest from the nanobiotechnological community owing to the significant progress made in robust and easy-to-make synthesis technologies, in surface functionalization, and in promising biomedical applications. These include bioimaging, gene diagnostics, analytical sensing, photothermal treatment of tumors, and targeted delivery of various biomolecular and chemical cargos. For the last-named application, gold nanoparticles should be properly fabricated to deliver the cargo into the targeted cells through effective endocytosis. In this review, we discuss recent progress in understanding the selective penetration of gold nanoparticles into immune cells. The interaction of gold nanoparticles with immune cell receptors is discussed. As distinct from other published reviews, we present a summary of the immunological properties of gold nanoparticles. This review also summarizes what is known about the application of gold nanoparticles as an antigen carrier and adjuvant in immunization for the preparation of antibodies in vivo . For each of the above topics, the basic principles, recent advances, and current challenges are discussed. Thus, this review presents a detailed analysis of data on interaction of gold nanoparticles with immune cells. Emphasis is placed on the systematization of data over production of antibodies by using gold nanoparticles and adjuvant properties of gold nanoparticles. Specifically, we start our discussion with current data on interaction of various gold nanoparticles with immune cells. The next section describes existing technologies to improve production of antibodies in vivo by using gold nanoparticles conjugated with specific ligands. Finally, we describe what is known about adjuvant properties of bare gold or functionalized nanoparticles. In the Conclusion section, we present a short summary of reported data and some challenges and perspectives.

Socio-demographic characteristics of traditional gold smelters in Makassar, south Sulawesi, Indonesia

Science.gov (United States)

Habo Abbas, Hasriwiani; Sakakibara, Masayuki; Hakim Arma, Lukmanul; Hardi Yanti, Iva

2017-06-01

The traditional gold smelting in Makassar, South Sulawesi, Indonesia, is an informal work with the manufacture of gold jewelry as the core activity. Stages of the gold processing include panning, smelting, and refining with mercury. In the current study, we used a social demography analysis to classify the traditional gold smelter workers in this region. Data (e.g. sex, age, education level, time working, and income) were obtained from a questionnaire survey of 58 smelter workers in the Wajo and Tallo Sub-districts of Makassar. Results showed that 84.5% of the workers were males aged from 21 to 50 years with on the average 15 year of work. The gold smelter were last educated in elementary school (31.0%), junior high school (36.2%), and senior high school (27.6%) levels whereas 5.1% have no education. We found that the monthly income of an un-skilled worker was ∼Rp. 2 million (USD 147.0) whereas that of a skilled worker was between Rp. 2.5 million (USD 183.76) and Rp. 5 million (USD 367.51). An owner could earn over Rp. 5 million (USD 367.51) per month. The result suggested that the traditional gold smelting used rudimentary technique and attracted young people with a low education level. This business continues to exist because the worker earn sufficient income and may higher through mastering gold smelter proficiency.

Measurement of the isotope effect of the diffusion of silver and gold in gold and of silver in silver-gold alloys

International Nuclear Information System (INIS)

Wolter, D.

1974-01-01

The silver isotopes Ag 105 and Agsup(110m) and the gold isotopes Au 195 and Au 199 were used for isotope effect measurements. The isotope effect of the gold self-diffusion was measured on four monocrystals samples at about 850 0 C, that of silver in gold monocrystals at five different temperatures between 731 0 C and 1050 0 C. Furthermore, the isotope effect for silver at 904 0 C was measured on seven silver-gold alloys of varying silver concentration. The correlation factor was determined from the measurements. (HPOE/LH) [de

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

GOLD CLUSTER LABELS AND RELATED TECHNOLOGIES IN MOLECULAR MORPHOLOGY.

Energy Technology Data Exchange (ETDEWEB)

HAINFELD,J.F.; POWELL,R.D.

2004-02-04

Although intensely colored, even the largest colloidal gold particles are not, on their own, sufficiently colored for routine use as a light microscopy stain: only with very abundant antigens or with specialized illumination methods can bound gold be seen. Colloidal gold probes were developed primarily as markers for electron microscopy, for which their very high electron density and selectivity for narrow size distributions when prepared in different ways rendered them highly suited. The widespread use of gold labeling for light microscopy was made possible by the introduction of autometallographic enhancement methods. In these processes, the bound gold particles are exposed to a solution containing metal ions and a reducing agent; they catalyze the reduction of the ions, resulting in the deposition of additional metal selectively onto the particles. On the molecular level, the gold particles are enlarged up to 30-100 nm in diameter; on the macroscale level, this results in the formation of a dark stain in regions containing bound gold particles, greatly increasing visibility and contrast. The applications of colloidal gold have been described elsewhere in this chapter, we will focus on the use of covalently linked cluster complexes of gold and other metals. A gold cluster complex is a discrete molecular coordination compound comprising a central core, or ''cluster'' of electron-dense metal atoms, ligated by a shell of small organic molecules (ligands), which are linked to the metal atoms on the surface of the core. This structure gives clusters several important advantages as labels. The capping of the metal surface by ligands prevents non-specific binding to cell and tissue components, which can occur with colloidal gold. Cluster compounds are more stable and may be used under a wider range of conditions. Unlike colloidal gold, clusters do not require additional macromolecules such as bovine serum albumin or polyethylene glycol for

Targeting of Gold Deposits in Amazonian Exploration Frontiers using Knowledge- and Data-Driven Spatial Modeling of Geophysical, Geochemical, and Geological Data

Science.gov (United States)

Magalhães, Lucíola Alves; Souza Filho, Carlos Roberto

2012-03-01

This paper reports the application of weights-of-evidence, artificial neural networks, and fuzzy logic spatial modeling techniques to generate prospectivity maps for gold mineralization in the neighborhood of the Amapari Au mine, Brazil. The study area comprises one of the last Brazilian mineral exploration frontiers. The Amapari mine is located in the Maroni-Itaicaiúnas Province, which regionally hosts important gold, iron, manganese, chromite, diamond, bauxite, kaolinite, and cassiterite deposits. The Amapari Au mine is characterized as of the orogenic gold deposit type. The highest gold grades are associated with highly deformed rocks and are concentrated in sulfide-rich veins mainly composed of pyrrhotite. The data used for the generation of gold prospectivity models include aerogeophysical and geological maps as well as the gold content of stream sediment samples. The prospectivity maps provided by these three methods showed that the Amapari mine stands out as an area of high potential for gold mineralization. The prospectivity maps also highlight new targets for gold exploration. These new targets were validated by means of detailed maps of gold geochemical anomalies in soil and by fieldwork. The identified target areas exhibit good spatial coincidence with the main soil geochemical anomalies and prospects, thus demonstrating that the delineation of exploration targets by analysis and integration of indirect datasets in a geographic information system (GIS) is consistent with direct prospecting. Considering that work of this nature has never been developed in the Amazonian region, this is an important example of the applicability and functionality of geophysical data and prospectivity analysis in regions where geologic and metallogenetic information is scarce.

Facts and Fantasies about Gold

OpenAIRE

Klement, Joachim

2015-01-01

Due to the increasing popularity of gold as an investment the demand for effective risk management techniques for gold investments has increased as well. In this paper we analyze several drivers of the price of gold that have been proposed in the past. Our analysis indicates that short-term volatility of the price of gold remains rather unpredictable with many of the explanations like the fund flows in physical gold ETF either unreliable or unstable over time. Our analysis suggests that there...

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.

Electrocatalytic glucose oxidation at gold and gold-carbon nanoparticulate film prepared from oppositely charged nanoparticles

International Nuclear Information System (INIS)

Karczmarczyk, Aleksandra; Celebanska, Anna; Nogala, Wojciech; Sashuk, Volodymyr; Chernyaeva, Olga; Opallo, Marcin

2014-01-01

Graphical abstract: - Highlights: • Gold nanoparticulate film electrodes were prepared by layer-by-layer method from oppositely charged nanoparticles. • Positively charged nanoparticles play dominant role in glucose oxidation in alkaline solution. • Gold and gold-carbon nanoparticulate film electrodes exhibit similar glucose oxidation current and onset potential. - Abstract: Electrocatalytic oxidation of glucose was studied at nanoparticulate gold and gold-carbon film electrodes. These electrodes were prepared by a layer-by-layer method without application of any linker molecules. Gold nanoparticles were stabilized by undecane thiols functionalized by trimethyl ammonium or carboxylate groups, whereas the carbon nanoparticles were covered by phenylsulfonate functionalities. The gold nanoparticulate electrodes were characterized by UV-vis and XPS spectroscopy, atomic force microscopy and voltammetry, before and after heat-treatment. Heat-treatment facilitates the aggregation of the nanoparticles and affects the structure of the film. The comparison of the results obtained with film electrodes prepared from gold nanoparticles with the same charge and with gold-carbon nanoparticulate electrodes, proved that positively charged nanoparticles are responsible for the high electrocatalytic activity, whereas negatively charged ones act rather as a linker of the film

Fact Sheet - Final Air Toxics Rule for Gold Mine Ore Processing and Production

Science.gov (United States)

Fact sheet summarizing main points of National Emissions Standards for Hazardous Air Pollutants for gold ore processing and production facilities, the seventh largest source of mercury air emission in the United States.

A non-diazo approach to α-oxo gold carbenes via gold-catalyzed alkyne oxidation.

Science.gov (United States)

Zhang, Liming

2014-03-18

For the past dozen years, homogeneous gold catalysis has evolved from a little known topic in organic synthesis to a fully blown research field of significant importance to synthetic practitioners, due to its novel reactivities and reaction modes. Cationic gold(I) complexes are powerful soft Lewis acids that can activate alkynes and allenes toward efficient attack by nucleophiles, leading to the generation of alkenyl gold intermediates. Some of the most versatile aspects of gold catalysis involve the generation of gold carbene intermediates, which occurs through the approach of an electrophile to the distal end of the alkenyl gold moiety, and their diverse transformations thereafter. On the other hand, α-oxo metal carbene/carbenoids are highly versatile intermediates in organic synthesis and can undergo various synthetically challenging yet highly valuable transformations such as C-H insertion, ylide formation, and cyclopropanation reactions. Metal-catalyzed dediazotizations of diazo carbonyl compounds are the principle and most reliable strategy to access them. Unfortunately, the substrates contain a highly energetic diazo moiety and are potentially explosive. Moreover, chemists need to use energetic reagents to prepare them, putting further constrains on operational safety. In this Account, we show that the unique access to the gold carbene species in homogeneous gold catalysis offers an opportunity to generate α-oxo gold carbenes if both nucleophile and electrophile are oxygen. Hence, this approach would enable readily available and safer alkynes to replace hazardous α-diazo carbonyl compounds as precursors in the realm of gold carbene chemistry. For the past several years, we have demonstrated that alkynes can indeed effectively serve as precursors to versatile α-oxo gold carbenes. In our initial study, we showed that a tethered sulfoxide can be a suitable oxidant, which in some cases leads to the formation of α-oxo gold carbene intermediates. The

A Non-Diazo Approach to α-Oxo Gold Carbenes via Gold-Catalyzed Alkyne Oxidation

Science.gov (United States)

2015-01-01

For the past dozen years, homogeneous gold catalysis has evolved from a little known topic in organic synthesis to a fully blown research field of significant importance to synthetic practitioners, due to its novel reactivities and reaction modes. Cationic gold(I) complexes are powerful soft Lewis acids that can activate alkynes and allenes toward efficient attack by nucleophiles, leading to the generation of alkenyl gold intermediates. Some of the most versatile aspects of gold catalysis involve the generation of gold carbene intermediates, which occurs through the approach of an electrophile to the distal end of the alkenyl gold moiety, and their diverse transformations thereafter. On the other hand, α-oxo metal carbene/carbenoids are highly versatile intermediates in organic synthesis and can undergo various synthetically challenging yet highly valuable transformations such as C–H insertion, ylide formation, and cyclopropanation reactions. Metal-catalyzed dediazotizations of diazo carbonyl compounds are the principle and most reliable strategy to access them. Unfortunately, the substrates contain a highly energetic diazo moiety and are potentially explosive. Moreover, chemists need to use energetic reagents to prepare them, putting further constrains on operational safety. In this Account, we show that the unique access to the gold carbene species in homogeneous gold catalysis offers an opportunity to generate α-oxo gold carbenes if both nucleophile and electrophile are oxygen. Hence, this approach would enable readily available and safer alkynes to replace hazardous α-diazo carbonyl compounds as precursors in the realm of gold carbene chemistry. For the past several years, we have demonstrated that alkynes can indeed effectively serve as precursors to versatile α-oxo gold carbenes. In our initial study, we showed that a tethered sulfoxide can be a suitable oxidant, which in some cases leads to the formation of α-oxo gold carbene intermediates. The

Surface-stabilized gold nanocatalysts

Science.gov (United States)

Dai, Sheng [Knoxville, TN; Yan, Wenfu [Oak Ridge, TN

2009-12-08

A surface-stabilized gold nanocatalyst includes a solid support having stabilizing surfaces for supporting gold nanoparticles, and a plurality of gold nanoparticles having an average particle size of less than 8 nm disposed on the stabilizing surfaces. The surface-stabilized gold nanocatalyst provides enhanced stability, such as at high temperature under oxygen containing environments. In one embodiment, the solid support is a multi-layer support comprising at least a first layer having a second layer providing the stabilizing surfaces disposed thereon, the first and second layer being chemically distinct.

Preparation of gold nanoparticles and determination of their particles size via different methods

International Nuclear Information System (INIS)

Iqbal, Muhammad; Usanase, Gisele; Oulmi, Kafia; Aberkane, Fairouz; Bendaikha, Tahar; Fessi, Hatem; Zine, Nadia; Agusti, Géraldine; Errachid, El-Salhi; Elaissari, Abdelhamid

2016-01-01

Graphical abstract: Preparation of gold nanoparticles via NaBH_4 reduction method, and determination of their particle size, size distribution and morphology by using different techniques. - Highlights: • Gold nanoparticles were synthesized by NaBH_4 reduction method. • Excess of reducing agent leads to tendency of aggregation. • The particle size, size distribution and morphology were investigated. • Particle size was determined both experimentally as well as theoretically. - Abstract: Gold nanoparticles have been used in various applications covering both electronics, biosensors, in vivo biomedical imaging and in vitro biomedical diagnosis. As a general requirement, gold nanoparticles should be prepared in large scale, easy to be functionalized by chemical compound of by specific ligands or biomolecules. In this study, gold nanoparticles were prepared by using different concentrations of reducing agent (NaBH_4) in various formulations and their effect on the particle size, size distribution and morphology was investigated. Moreover, special attention has been dedicated to comparison of particles size measured by various techniques, such as, light scattering, transmission electron microscopy, UV spectrum using standard curve and particles size calculated by using Mie theory and UV spectrum of gold nanoparticles dispersion. Particle size determined by various techniques can be correlated for monodispersed particles and excess of reducing agent leads to increase in the particle size.

A halogen-free synthesis of gold nanoparticles using gold(III) oxide

International Nuclear Information System (INIS)

Sashuk, Volodymyr; Rogaczewski, Konrad

2016-01-01

Gold nanoparticles are one of the most used nanomaterials. They are usually synthesized by the reduction of gold(III) chloride. However, the presence of halide ions in the reaction mixture is not always welcome. In some cases, these ions have detrimental influence on the morphology and structure of resulting nanoparticles. Here, we present a simple and halogen-free procedure to prepare gold nanoparticles by reduction of gold(III) oxide in neat oleylamine. The method provides the particles with an average size below 10 nm and dispersity of tens of percent. The process of nanoparticle formation was monitored using UV–Vis spectroscopy. The structure and chemical composition of the nanoparticles was determined by SEM, XPS and EDX. We also proposed the mechanism of reduction of gold(III) oxide based on MS, IR and NMR data. Importantly, the synthetic protocol is general and applicable for the preparation of other coinage metal nanoparticles from the corresponding metal oxides. For instance, we demonstrated that the absence of halogen enables efficient alloying of metals when preparing gold–silver bimetallic nanoparticles.

Validation of different measures of insulin sensitivity of glucose metabolism in dairy cows using the hyperinsulinemic euglycemic clamp test as the gold standard.

Science.gov (United States)

De Koster, J; Hostens, M; Hermans, K; Van den Broeck, W; Opsomer, G

2016-10-01

The aim of the present research was to compare different measures of insulin sensitivity in dairy cows at the end of the dry period. To do so, 10 clinically healthy dairy cows with a varying body condition score were selected. By performing hyperinsulinemic euglycemic clamp (HEC) tests, we previously demonstrated a negative association between the insulin sensitivity and insulin responsiveness of glucose metabolism and the body condition score of these animals. In the same animals, other measures of insulin sensitivity were determined and the correlation with the HEC test, which is considered as the gold standard, was calculated. Measures derived from the intravenous glucose tolerance test (IVGTT) are based on the disappearance of glucose after an intravenous glucose bolus. Glucose concentrations during the IVGTT were used to calculate the area under the curve of glucose and the clearance rate of glucose. In addition, glucose and insulin data from the IVGTT were fitted in the minimal model to derive the insulin sensitivity parameter, Si. Based on blood samples taken before the start of the IVGTT, basal concentrations of glucose, insulin, NEFA, and β-hydroxybutyrate were determined and used to calculate surrogate indices for insulin sensitivity, such as the homeostasis model of insulin resistance, the quantitative insulin sensitivity check index, the revised quantitative insulin sensitivity check index and the revised quantitative insulin sensitivity check index including β-hydroxybutyrate. Correlation analysis revealed no association between the results obtained by the HEC test and any of the surrogate indices for insulin sensitivity. For the measures derived from the IVGTT, the area under the curve for the first 60 min of the test and the Si derived from the minimal model demonstrated good correlation with the gold standard. Copyright © 2016 Elsevier Inc. All rights reserved.

Factors Affecting Elevated Arsenic and Methyl Mercury Concentrations in Small Shield Lakes Surrounding Gold Mines near the Yellowknife, NT, (Canada Region.

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Adam James Houben

Full Text Available Gold mines in the Yellowknife, NT, region--in particular, the Giant Mine--operated from 1949-99, releasing 237,000 tonnes of waste arsenic trioxide (As2O3 dust, among other compounds, from gold ore extraction and roasting processes. For the first time, we show the geospatial distribution of roaster-derived emissions of several chemical species beyond the mine property on otherwise undisturbed taiga shield lakes within a 25 km radius of the mine, 11 years after its closing. Additionally, we demonstrate that underlying bedrock is not a significant source for the elevated concentrations in overlying surface waters. Aquatic arsenic (As concentrations are well above guidelines for drinking water (10 μg/L and protection for aquatic life (5 μg/L, ranging up to 136 μg/L in lakes within 4 km from the mine, to 2.0 μg/L in lakes 24 km away. High conversion ratios of methyl mercury were shown in lakes near the roaster stack as well, with MeHg concentrations reaching 44% of total mercury. The risk of elevated exposures by these metals is significant, as many lakes used for recreation and fishing near the City of Yellowknife are within this radius of elevated As and methyl Hg concentrations.

Determination of phosphorus in gold or silver brazing alloys

International Nuclear Information System (INIS)

Antepenko, R.J.

1976-01-01

A spectrophotometric method has been devised for measuring microgram levels of phosphorus in brazing alloys of gold or silver alloys is normally measured by solid mass spectrometry, but the high nickel concentration produces a double ionized nickel spectral interference. The described procedures is based upon the formation of molybdovandophosphoric acid when a molybdate solution is added to an acidic solution containing orthophosphate and vanadate ions. The optimum acidity for forming the yellow colored product is 0.5 N hydrochloric acid. The working concentration range is from 0.1 to 1 ppm phosphorus using 100-mm cells and measuring the absorbance at 460 nm. The sample preparation procedure employs aqua regia to dissolve the alloy oxidize the phosphorus to orthophosphate. Cation-exchange chromatography is used to remove nickel ions and anion-exchange and chromatography to remove gold ions as the chloride complex. Excellent recoveries are obtained for standard phosphorus solutions run through the sample procedure. The procedure is applicable to a variety of gold or silver braze alloys requiring phosphorus analysis

Structure and bonding in gold compounds

International Nuclear Information System (INIS)

Parish, R.V.

1988-01-01

Recent developments in chemical applications of 197 Au Moessbauer spectroscopy are reviewed. For gold(I) and gold(III), systematic variations in isomer shift and quadrupole splitting are seen as the ligands are changed; the effects of change in coordination number of the gold atoms are also systematic. Data for gold(II) systems involving gold-gold bonds lie between those for corresponding gold(I) and gold(III) materials, showing a small increase in isomer shift and a larger increase in quadrupole splitting as the oxidation state decreases; these trends are explained in terms of the structures. Data for mixed-metal cluster compounds are much more sensitive to structural effects than in homonuclear clusters. Both sets of data show systematic changes with increase in the number of metal atoms to which the gold atom is bound. The connectivity also influences the recoil-free fraction. (orig.)

Neutron cross section standards for the energy region above 20 MeV

International Nuclear Information System (INIS)

1991-01-01

These proceedings of a specialists' meeting on Neutron cross section standards for the energy region above 20 MeV are divided into 6 sessions bearing on: - session 1: status of the date base for (n-p) scattering (2 conferences) - session 2: status of nucleon-nucleon phase shift calculations (1 conference) - session 3: recent and planned experimental work on n-p cross section measurements and facilities (7 conferences) - session 4: Instruments for utilizing the H (n.n) standard for neutron fluence measurement (4 conferences) - session 5: proposal for other neutron cross-section standards (4 conferences) - session 6: monitor reactions for radiation dosimetry (3 conferences)

75 FR 40819 - Reliability Standards Development and NERC and Regional Entity Enforcement; Notice Soliciting...

Science.gov (United States)

2010-07-14

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. AD10-14-000] Reliability Standards Development and NERC and Regional Entity Enforcement; Notice Soliciting Comments July 7, 2010... technical conference to explore issues pertaining to the development of mandatory Reliability Standards for...

The Challenges of Supply Chain in the Gold Mining Sector of Obuasi Municipality of Ghana

Directory of Open Access Journals (Sweden)

Ernest Kwaku Agyei

2013-10-01

Full Text Available Gold mining industry represents an important source of socio-economic development in most economies. Ghana has had its fair share of the benefits the mining sector brings by way of direct revenue generation and job creation. In spite of this significant contribution from gold mining, the sector appears to be facing various forms of challenges. This study aims at assessing the supply chain challenges facing the gold mining operations in Obuasi and its environs in the Ashanti region of Ghana. A combination of qualitative and quantitative methods with case study strategy was used in the study. Primary data was collected from field survey through questionnaires, semi-structured interviews and observation. The data was analysed using quantitative and qualitative approaches. The major supply chain challenges found to be facing the mining sector in Obuasi include supply of low quality products, unreliable or variable lead times, non-availability of local firms of international standard, fluctuation in Gold prices on the international market, high transportation cost and violence and sporadic attack from the communities. It is recommended that the mining firms should involve their key and strategic suppliers in product designs and development of specifications. Also, improving upon information sharing and building trust and transparency and developing the capacities of their key suppliers to improve the performances of the entire supply chain could also deal with delays and quality related supplies. Finally the Ministry of Energy, the Environmental Protection Agency and other institutions should collaborate with the mining firms to deal with issues of environmental pollution and matters of perceived inadequate compensation to community members whose farm lands get destroyed by the mining activities to address any unhealthy conflicts between the mining firms and the communities.

Utilising magnetic resonance imaging as the gold-standard in management of suspected scaphoid fractures in the emergency department setting

LENUS (Irish Health Repository)

Ramasubbu, B

2017-02-01

Scaphoid fractures are the most common carpal bone fracture. Up to 40% of scaphoid fractures can be missed at initial presentation and investigation. Follow-up plain film radiograph has overall poor sensitivity and reliability. MRI has been shown to have an almost 100% sensitivity and specificity and so is the gold standard in scaphoid fracture diagnosis. Additionally, early specialist involvement is recommended. We proposed that following a designated pathway, there would be no significant increase in MRI requests. Following implementation of a pathway for the management of suspected scaphoid fractures in St James’s Hospital in 2012 re-auditing demonstrated that management changed to either MRI directly after initial x-ray (16\\/145, 11%), MRI after second x-ray (9\\/28, 32%) or orthopaedic follow-up (19\\/28, 68%). The number of MRIs requested was consistent with our predictors of demand. Thus, our new protocol maximises diagnostics, cost effectiveness and quality of patient care.

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.

The Berezitovoe gold-polymetallic deposit (Upper Amur region, Russia: Structure, mineralogy and genetic aspects

Directory of Open Access Journals (Sweden)

Alexandr S. Vakh

2016-05-01

Full Text Available The Berezitovoe deposit in the Sergachi volcano-plutonic and metallogenic belt preserves evidence for polymetallic mineralization of multiple stages. The steeply dipping garnet-tourmaline-muscovite-quartz metasomatites (with K-Ar ages of 132 ± 2.9 and 127 ± 4.4 Ma carry two distinct stages of mineralization developed at different times: (1 polymetallic mineralization and (2 gold-quartz. The deposit is located within Paleozoic gneissose granitoids of the Pikansky complex (dated as 379 ± 1.1 Ma by zircon U-Pb method intruded by early Cretaceous porphyry-like granites of the Haikta pluton (dated as 137 ± 0.67 Ma by zircon U-Pb method and late Cretaceous dikes of porphyrites, porphyries, and lamprophyres. Evidence suggests the action of late gold-bearing hydrothermal fluids on the early polymetallic ores and the selective mobilization of some elements from these lead to redeposition together with complex sulphosalts.

Impacts of surface gold mining on land use systems in Western Ghana.

Science.gov (United States)

Schueler, Vivian; Kuemmerle, Tobias; Schröder, Hilmar

2011-07-01

Land use conflicts are becoming increasingly apparent from local to global scales. Surface gold mining is an extreme source of such a conflict, but mining impacts on local livelihoods often remain unclear. Our goal here was to assess land cover change due to gold surface mining in Western Ghana, one of the world's leading gold mining regions, and to study how these changes affected land use systems. We used Landsat satellite images from 1986-2002 to map land cover change and field interviews with farmers to understand the livelihood implications of mining-related land cover change. Our results showed that surface mining resulted in deforestation (58%), a substantial loss of farmland (45%) within mining concessions, and widespread spill-over effects as relocated farmers expand farmland into forests. This points to rapidly eroding livelihood foundations, suggesting that the environmental and social costs of Ghana's gold boom may be much higher than previously thought.

Dental Hygiene Faculty Calibration Using Two Accepted Standards for Calculus Detection: A Pilot Study.

Science.gov (United States)

Santiago, Lisa J; Freudenthal, Jacqueline J; Peterson, Teri; Bowen, Denise M

2016-08-01

Faculty calibration studies for calculus detection use two different standards for examiner evaluation, yet the only therapeutic modality that can be used for nonsurgical periodontal treatment is scaling/root debridement or planing. In this study, a pretest-posttest design was used to assess the feasibility of faculty calibration for calculus detection using two accepted standards: that established by the Central Regional Dental Testing Service, Inc. (CRDTS; readily detectible calculus) and the gold standard for scaling/root debridement (root roughness). Four clinical dental hygiene faculty members out of five possible participants at Halifax Community College agreed to participate. The participants explored calculus on the 16 assigned teeth (64 surfaces) of four patients. Calculus detection scores were calculated before and after training. Kappa averages using CRDTS criteria were 0.561 at pretest and 0.631 at posttest. Kappa scores using the scaling/root debridement or planing standard were 0.152 at pretest and 0.271 at posttest. The scores indicated improvement from moderate (Kappa=0.41-0.60) to substantial agreement (Kappa=0.61-0.80) following training using the CRDTS standard. Although this result differed qualitatively and Kappas were significantly different from 0, the differences for pre- to post-Kappas for patient-rater dyads using CRDTS were not statistically significant (p=0.778). There was no difference (p=0.913) in Kappa scores pre- to post-training using the scaling/root debridement standard. Despite the small number of participants in this study, the results indicated that training to improve interrater reliability to substantial agreement was feasible using the CRDTS standard but not using the gold standard. The difference may have been due to greater difficulty in attaining agreement regarding root roughness. Future studies should include multiple training sessions with patients using the same standard for scaling/root debridement used for

Metal-organic framework templated electrodeposition of functional gold nanostructures

International Nuclear Information System (INIS)

Worrall, Stephen D.; Bissett, Mark A.; Hill, Patrick I.; Rooney, Aidan P.; Haigh, Sarah J.; Attfield, Martin P.; Dryfe, Robert A.W.

2016-01-01

Highlights: • Electrodeposition of anisotropic Au nanostructures templated by HKUST-1. • Au nanostructures replicate ∼1.4 nm pore spaces of HKUST-1. • Encapsulated Au nanostructures active as SERS substrate for 4-fluorothiophenol. - Abstract: Utilizing a pair of quick, scalable electrochemical processes, the permanently porous MOF HKUST-1 was electrochemically grown on a copper electrode and this HKUST-1-coated electrode was used to template electrodeposition of a gold nanostructure within the pore network of the MOF. Transmission electron microscopy demonstrates that a proportion of the gold nanostructures exhibit structural features replicating the pore space of this ∼1.4 nm maximum pore diameter MOF, as well as regions that are larger in size. Scanning electron microscopy shows that the electrodeposited gold nanostructure, produced under certain conditions of synthesis and template removal, is sufficiently inter-grown and mechanically robust to retain the octahedral morphology of the HKUST-1 template crystals. The functionality of the gold nanostructure within the crystalline HKUST-1 was demonstrated through the surface enhanced Raman spectroscopic (SERS) detection of 4-fluorothiophenol at concentrations as low as 1 μM. The reported process is confirmed as a viable electrodeposition method for obtaining functional, accessible metal nanostructures encapsulated within MOF crystals.

Separation and enrichment of gold(III) from environmental samples prior to its flame atomic absorption spectrometric determination

International Nuclear Information System (INIS)

Senturk, Hasan Basri; Gundogdu, Ali; Bulut, Volkan Numan; Duran, Celal; Soylak, Mustafa; Elci, Latif; Tufekci, Mehmet

2007-01-01

A simple and accurate method was developed for separation and enrichment of trace levels of gold in environmental samples. The method is based on the adsorption of Au(III)-diethyldithiocarbamate complex on Amberlite XAD-2000 resin prior to the analysis of gold by flame atomic absorption spectrometry after elution with 1 mol L -1 HNO 3 in acetone. Some parameters including nitric acid concentration, eluent type, matrix ions, sample volume, sample flow rate and adsorption capacity were investigated on the recovery of gold(III). The recovery values for gold(III) and detection limit of gold were greater than 95% and 16.6 μg L -1 , respectively. The preconcentration factor was 200. The relative standard deviation of the method was -1 . The validation of the presented procedure was checked by the analysis of CRM-SA-C Sandy Soil certified reference material. The presented procedure was applied to the determination of gold in some environmental samples

Novel solid phase extraction procedure for gold(III) on Dowex M 4195 prior to its flame atomic absorption spectrometric determination

International Nuclear Information System (INIS)

Tuzen, Mustafa; Saygi, Kadriye O.; Soylak, Mustafa

2008-01-01

A method for solid phase extraction (SPE) of gold(III) using Dowex M 4195 chelating resin has been developed. The optimum experimental conditions for the quantitative sorption of gold(III), pH, effect of flow rates, eluent types, sorption capacity and the effect of diverse ions on the sorption of gold(III) have been investigated. The chelating resin can be reused for more than 100 cycles of sorption-desorption without any significant change in sorption of gold(III) ions. The recovery values for gold(III) and detection limit (LOD) of gold were greater than 95% and 1.61 μg L -1 , respectively. The preconcentration factor was 31. The relative standard deviation of the method was -1 . The proposed method has been applied for the determination of gold(III) in some real samples including water, soil and sediment samples

National Accreditation and Its Role in Early Education: An Analysis of Florida's Gold Seal Quality Child-Care Program and Licensing Standards

Science.gov (United States)

Winterbottom, Christian; Jones, Ithel

2014-01-01

This article reports on the first Florida statewide assessment of the Gold Seal Quality Care program, accreditation, and the relationship with licensing violations. This study analyzed the differences between the Department of Children and Families Gold Seal-Accredited facilities and nonaccredited facilities by comparing the facilities and the…

Effect of Gold Marker Seeds on Magnetic Resonance Spectroscopy of the Prostate

Energy Technology Data Exchange (ETDEWEB)

Hossain, Murshed, E-mail: Murshed.Hossain@fccc.edu [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Schirmer, Timo [Global MR Applied Science Laboratory, GE Healthcare, Munich (Germany); Richardson, Theresa; Chen, Lili; Buyyounouski, Mark K.; Ma Changming [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States)

2012-05-01

Purpose: Magnetic resonance stereoscopic imaging (MRSI) of the prostate is an emerging technique that may enhance targeting and assessment in radiotherapy. Current practices in radiotherapy invariably involve image guidance. Gold seed fiducial markers are often used to perform daily prostate localization. If MRSI is to be used in targeting prostate cancer and therapy assessment, the impact of gold seeds on MRSI must be investigated. The purpose of this study was to quantify the effects of gold seeds on the quality of MRSI data acquired in phantom experiments. Methods and Materials: A cylindrical plastic phantom with a spherical cavity 10 centimeters in diameter wss filled with water solution containing choline, creatine, and citrate. A gold seed fiducial marker was put near the center of the phantom mounted on a plastic stem. Spectra were acquired at 1.5 Tesla by use of a clinical MRSI sequence. The ratios of choline + creatine to citrate (CC/Ci) were compared in the presence and absence of gold seeds. Spectra in the vicinity of the gold seed were analyzed. Results: The maximum coefficient of variation of CC/Ci induced by the gold seed was found to be 10% in phantom experiments at 1.5 T. Conclusion: MRSI can be used in prostate radiotherapy in the presence of gold seed markers. Gold seeds cause small effects (in the order of the standard deviation) on the ratio of the metabolite's CC/Ci in the phantom study done on a 1.5-T scanner. It is expected that gold seed markers will have similar negligible effect on spectra from prostate patients. The maximum of 10% of variation in CC/Ci found in the phantom study also sets a limit on the threshold accuracy of CC/Ci values for deciding whether the tissue characterized by a local spectrum is considered malignant and whether it is a candidate for local boost in radiotherapy dose.

Effect of Gold Marker Seeds on Magnetic Resonance Spectroscopy of the Prostate

International Nuclear Information System (INIS)

Hossain, Murshed; Schirmer, Timo; Richardson, Theresa; Chen, Lili; Buyyounouski, Mark K.; Ma Changming

2012-01-01

Purpose: Magnetic resonance stereoscopic imaging (MRSI) of the prostate is an emerging technique that may enhance targeting and assessment in radiotherapy. Current practices in radiotherapy invariably involve image guidance. Gold seed fiducial markers are often used to perform daily prostate localization. If MRSI is to be used in targeting prostate cancer and therapy assessment, the impact of gold seeds on MRSI must be investigated. The purpose of this study was to quantify the effects of gold seeds on the quality of MRSI data acquired in phantom experiments. Methods and Materials: A cylindrical plastic phantom with a spherical cavity 10 centimeters in diameter wss filled with water solution containing choline, creatine, and citrate. A gold seed fiducial marker was put near the center of the phantom mounted on a plastic stem. Spectra were acquired at 1.5 Tesla by use of a clinical MRSI sequence. The ratios of choline + creatine to citrate (CC/Ci) were compared in the presence and absence of gold seeds. Spectra in the vicinity of the gold seed were analyzed. Results: The maximum coefficient of variation of CC/Ci induced by the gold seed was found to be 10% in phantom experiments at 1.5 T. Conclusion: MRSI can be used in prostate radiotherapy in the presence of gold seed markers. Gold seeds cause small effects (in the order of the standard deviation) on the ratio of the metabolite's CC/Ci in the phantom study done on a 1.5-T scanner. It is expected that gold seed markers will have similar negligible effect on spectra from prostate patients. The maximum of 10% of variation in CC/Ci found in the phantom study also sets a limit on the threshold accuracy of CC/Ci values for deciding whether the tissue characterized by a local spectrum is considered malignant and whether it is a candidate for local boost in radiotherapy dose.

Building Capacity in Using Earth Observations Under the GOFC-GOLD and TAT Programs

Science.gov (United States)

Gutman, G.

2015-12-01

The Global Observation of Forest and Land Cover Dynamics (GOFC-GOLD) is a coordinated international effort to provide ongoing space-based and in-situ observations of forests and other vegetation cover. The main goal of GOFC/GOLD is to support a forum for international information exchange, observation and data coordination, and a framework for establishing the necessary long-term monitoring systems. GOFC-GOLD has two Implementation Teams: Land Cover Characteristics and Change, and Fire Monitoring and Mapping. Additionally, it includes two working groups: the Working Group on Biomass Monitoring and the Working group on Reducing Emissions from Deforestation and Forest Degradation (REDD), the latter being aligned with the United Nations Framework Convention on Climate Change. Regional networks are an integral part of the GOFC-GOLD program, with some networks fully developed and some still emerging. GOFC-GOLD provides training workshops to build capacity in the regions. Capacity building in using Earth Observation techniques and applications is also promoted by cooperation of NASA and ESA under the Trans-Atlantic Training (TAT) program. The main objective of TAT is training of early career scientists and students in East European and Baltic countries emphasizing outstanding technical issues in remote sensing of land-cover/land-use change and ecosystems processes. TAT promotes data sharing and advanced research methods and technologies through series of training sessions. Three TAT sessions have been held until now, each session consisting of 5-10 tutors and about 30 early career scientists and students from Eastern Europe. The sessions include lectures on remote sensing covering the full solar spectrum and hands-on practice. The experience obtained in capacity building activities under GOFC-GOLD and TAT will be shared with the audience.

New evidence on the composition of mineral grains of native gold

International Nuclear Information System (INIS)

Erasmus, C.S.; Sellschop, J.P.F.; Watterson, J.I.W.

1987-01-01

The nuclear analytical techniques of instrumental neutron activation and radiochemical neutron activation have been applied to the analysis of native gold from the Precambrian Witwatersrand Sequence and from the Archaen deposits in the Barberton Mountain Land, Murchison Range and Pietersburg region in South Africa. A total of 15 elements were determined in the samples of native gold, namely: scandium, iron, cobalt, nickel, copper, zinc, zirconium, silver, antimony, tellurium, cerium, europium, ytterbium, mercury and thorium. Of these the silver and mercury were determined by the instrumental procedure and the copper was determined after extraction with diethyl dithiocarbamate. The other elements were determined from long-lived isotopes after the removal of silver by dissolution of the gold and precipitation of the silver as silver iodide. The most significant result of this work is the discovery that mercury occurs at the percentage level in native gold from the Witwatersrand (between 1 and 5%), demonstrating the power of the nuclear method in comparison with conventional methods such as optical spectroscopy and the electron microprobe, which had failed to make this discovery. (author)

Effect of pH and chloroauric acid concentration on the geometry of gold nanoparticles obtained by photochemical synthesis

Science.gov (United States)

Conde Rodríguez, G. R.; Gauthier, G. H.; Ladeira, L. O.; Sanabria Cala, J. A.; Laverde Cataño, D.

2017-12-01

Due to their excellent surface properties, gold nanoparticles have been used in a wide range of applications from optics and catalysis to biology and cancer treatment by thermal therapy. Gold nanoparticles can absorb a large amount of radiation according to their geometry, such as nanospheres and nanorods. The importance of gold nanoparticles geometry is based on the electromagnetic spectrum wavelength where exists a greater absorption of radiation, which belongs to the visible region for nanospheres and ranges between visible and near infrared regions for nanorods, conferring greater biomedical applicability to the latter. When using photochemical synthesis method, which consists of reducing gold atoms to their metallic state with UV radiation, the geometry of gold nanoparticles depends on different variables such as: 1) pH, 2) concentration of chloroauric acid, 3) the surfactant, 4) concentration of silver nitrate, 5) temperature and 6) irradiation time. Therefore, in this study the geometry of the gold nanoparticles obtained by photochemical synthesis was determined as a function of solution pH and chloroauric acid concentration, using Spectrophotometry in the Ultraviolet Visible region (UV-vis) as characterization technique. From the analysis of the UV-vis spectra, it was determined that at an acidic pH the particles have two absorption bands corresponding to nanorods geometry, while at a basic pH only nanospheres are found and at a neutral pH the lower relative intensity of the second band indicates the simultaneous existence of the two geometries. The increase in the concentration of chloroauric acid produces a decrease in the amount of synthesized nanorods, seen as a decrease of the relative intensity of the second absorption band. Therefore, obtaining gold nanoparticles with nanorods geometry favours fields such as biomedicine, because they are capable of absorbing infrared radiation and can be used as photosensitive agents in localized thermal therapy

75 FR 39244 - Reliability Standards Development and NERC and Regional Entity Enforcement; Further Notice...

Science.gov (United States)

2010-07-08

... Standards Development and NERC and Regional Entity Enforcement; Further Notice Concerning Technical... convene a Commissioner-led technical conference regarding issues pertaining to the development of... Corporation and the Regional Entities as previously announced.\\1\\ \\1\\ Notice of Technical Conference, 75 FR 35...

Determination of Gold from Gold Matrix of North Western Nigeria ...

African Journals Online (AJOL)

The research paper presents analytical results of Au, Mn and V concentrations of some Nigerian gold ores using two techniques: epithermal neutron activation analysis (ENAA) and proton induced X-ray emission (PIXE). Fourteen samples were collected from gold fields of North Western Nigeria, prepared separately to a ...

Sleep apnea detection by a cardiac resynchronization device integrated thoracic impedance sensor: A validation study against the gold standard polysomnography.

Science.gov (United States)

Barbieri, Fabian; Dichtl, Wolfgang; Heidbreder, Anna; Brandauer, Elisabeth; Stefani, Ambra; Adukauskaite, Agne; Senoner, Thomas; Schgör, Wilfried; Hintringer, Florian; Högl, Birgit

2018-01-01

Sleep disordered breathing is a common but often undiagnosed comorbidity in heart failure patients. Cardiac implantable electronic devices used for cardiac resynchronization therapy (CRT) may detect sleep apnea by use of a transthoracic impedance sensor. Validation of the AP scan® algorithm (Boston Scientific®) was performed by using the diagnostic gold standard polysomnography (PSG). Forty-one patients with impaired left ventricular ejection fraction, frequent right ventricular pacing due to atrioventricular block and heart failure symptoms despite optimal medical therapy underwent upgrading to biventricular pacing. Within one month after left ventricular lead implantation, sleep apnea was assessed by single-night PSG and AP scan® measurements. AP scan® measurements were valid in only 21 of 41 (51.2%) patients in the index night of the PSG. The PSG determined apnea-hypopnea index did not correlate statistically significant with the AP scan® measurements (r = 0.41, 95% confidence interval -0.05-0.72, p = 0.07). The degree of overestimation is displayed by using the Bland-Altman method: mean difference -12.4, standard deviation ± 15.8, 95% confidence interval -43.3-18.6. In heart failure patients receiving CRT upgrading, the AP scan® algorithm may need further improvement before it can be recommended for sleep apnea detection.

Interaction between manufactured gold nanoparticles and naturally occurring organic macromolecules

International Nuclear Information System (INIS)

Diegoli, Sara; Manciulea, Adriana L.; Begum, Shakiela; Jones, Ian P.; Lead, Jamie R.; Preece, Jon A.

2008-01-01

The increasing exploitation of nanomaterials into many consumer and other products is raising concerns as these nanomaterials are likely to be released into the environment. Due to our lack of knowledge about the environmental chemistry, transport and ecotoxicology of nanomaterials, it is of paramount importance to study how natural aquatic colloids can interact with manufactured gold nanoparticles as these interactions will determine their environmental fate and behaviour. In this context, our work aims to quantify the effect of naturally occurring riverine macromolecules - International Humic Substances Society (IHSS) Suwannee River Humic Acid Standard (SRHA) - on citrate- and acrylate-stabilized gold nanoparticles. The influence of SRHA on the stability of the gold colloids was studied as a function of pH by UV-visible absorption spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). At high ionic strengths (0.1 M), extensive and rapid aggregation occurred, while more subtle effects were observed at lower ionic strength values. Evidence was found that SRHA enhances particle stability at extreme pH values (ionic strength < 0.01 M) by substituting and/or over-coating the original stabilizer on the gold nanoparticle surface, thus affecting surface charge and chemistry. These findings have important implications for the fate and behaviour of nanoparticles in the environment and their ecotoxicity

Analysis of gold(I/III)-complexes by HPLC-ICP-MS demonstrates gold(III) stability in surface waters.

Science.gov (United States)

Ta, Christine; Reith, Frank; Brugger, Joël; Pring, Allan; Lenehan, Claire E

2014-05-20

Understanding the form in which gold is transported in surface- and groundwaters underpins our understanding of gold dispersion and (bio)geochemical cycling. Yet, to date, there are no direct techniques capable of identifying the oxidation state and complexation of gold in natural waters. We present a reversed phase ion-pairing HPLC-ICP-MS method for the separation and determination of aqueous gold(III)-chloro-hydroxyl, gold(III)-bromo-hydroxyl, gold(I)-thiosulfate, and gold(I)-cyanide complexes. Detection limits for the gold species range from 0.05 to 0.30 μg L(-1). The [Au(CN)2](-) gold cyanide complex was detected in five of six waters from tailings and adjacent monitoring bores of working gold mines. Contrary to thermodynamic predictions, evidence was obtained for the existence of Au(III)-complexes in circumneutral, hypersaline waters of a natural lake overlying a gold deposit in Western Australia. This first direct evidence for the existence and stability of Au(III)-complexes in natural surface waters suggests that Au(III)-complexes may be important for the transport and biogeochemical cycling of gold in surface environments. Overall, these results show that near-μg L(-1) enrichments of Au in environmental waters result from metastable ligands (e.g., CN(-)) as well as kinetically controlled redox processes leading to the stability of highly soluble Au(III)-complexes.

Complexes of DNA bases and Watson-Crick base pairs with small neutral gold clusters.

Science.gov (United States)

Kryachko, E S; Remacle, F

2005-12-08

The nature of the DNA-gold interaction determines and differentiates the affinity of the nucleobases (adenine, thymine, guanine, and cytosine) to gold. Our preliminary computational study [Kryachko, E. S.; Remacle, F. Nano Lett. 2005, 5, 735] demonstrates that two major bonding factors govern this interaction: the anchoring, either of the Au-N or Au-O type, and the nonconventional N-H...Au hydrogen bonding. In this paper, we offer insight into the nature of nucleobase-gold interactions and provide a detailed characterization of their different facets, i.e., geometrical, energetic, and spectroscopic aspects; the gold cluster size and gold coordination effects; proton affinity; and deprotonation energy. We then investigate how the Watson-Crick DNA pairing patterns are modulated by the nucleobase-gold interaction. We do so in terms of the proton affinities and deprotonation energies of those proton acceptors and proton donors which are involved in the interbase hydrogen bondings. A variety of properties of the most stable Watson-Crick [A x T]-Au3 and [G x C]-Au3 hybridized complexes are described and compared with the isolated Watson-Crick A x T and G x C ones. It is shown that enlarging the gold cluster size to Au6 results in a rather short gold-gold bond in the Watson-Crick interbase region of the [G x C]-Au6 complex that bridges the G x C pair and thus leads to a significant strengthening of G x C pairing.

Multidetector CT: a new gold standard in the diagnosis of pulmonary embolism? State of the art and diagnostic algorithms; La TC multitettore: il nuovo gold standard nella diagnosi di embolia polmonare? Stato dell'arte e algoritmi diagnostici

Energy Technology Data Exchange (ETDEWEB)

Russo, Vincenzo; Piva, Tommaso; Lovato, Luigi; Fattori, Rossella; Gavelli, Giampaolo [Policlinico S. Orsola, Bologna (Italy). Dipartimento di Radiologia Radiologia III

2005-02-01

Purpose: From the early 90s, spiral CT technology has considerably changed the diagnostic capability of Pulmonary Embolism (PE), giving a direct vision of intravascular thrombi. Further technological progress has straightened its diagnostic impact leading to an essential role in clinical practice. The advent of Multi-Detector CT (MDCT) has subsequently increased the reliability of this technique to the point of undermining the role of pulmonary angiography as the gold standard and occupying a central position in diagnostic algorithms. The aim of this paper is to appraise this evolution by means of a meta-analysis of the relevant literature from 1995 to 2004. Results: The review of the literature showed the sensitivity and specificity of CT to have increased from 37-94% and 91-100% (single detector CT) to 87-94% and 94-100% (4-channel multidetector CT), especially thanks to the possibility of depicting subsegmental clots, with an interobserver agreement of 0.63-0.94 (k). Conclusions: CT is one of the most reliable and effective methods in the diagnosis is PE, with the advantage of being extremely fast and providing alternative diagnoses. Recent improvements in MDCT technology confers the highest value of diagnostic accuracy with respect to other imaging modalities such as scintigraphy, angiography, MRI, D-dimer essay and Doppler US. [Italian] Scopo: Dall'inizio degli anni '90, la tecnologia TC spirale (TCS) ha cambiato notevolmente la capacita' diagnostica di Embolia Polmonare (EP), fornendo una visione diretta dei trombi endoluminali. Successivi progressi tecnologici hanno fortificato il suo impatto diagnostico a tal punto che questa metodica e' ora essenziale nella pratica clinica. L'avvento della TC Multi-Detettore (TCMD) ha aumentato di conseguenza l'affidabilita' di questa tecnica fino a tal punto da scalzare l'angiopneumografia dal ruolo di Gold Standard ed occupare una posizione cantrale negli algoritmi diagnostici

Gold markers for tumor localization and target volume delineation in radiotherapy for rectal cancer

International Nuclear Information System (INIS)

Vorwerk, Hilke; Christiansen, Hans; Hess, Clemens Friedrich; Hermann, Robert Michael; Liersch, Thorsten; Ghadimi, Michael; Rothe, Hilka

2009-01-01

In locally advanced rectal cancer, neoadjuvant radiochemotherapy is indicated. To improve target volume definition for radiotherapy planning, the potential of implanted gold markers in the tumor region was evaluated. In nine consecutive patients, two to three gold markers were implanted in the tumor region during rigid rectoscopy. Computed tomography scans were performed during treatment planning. All electronic portal imaging devices (EPIDs) recorded during treatment series were analyzed. All patients underwent complete tumor resection with meticulous histopathologic examination. The gold markers could easily be implanted into the mesorectal tissue at the caudal tumor border without any complications. They were helpful in identifying the inferior border of the planning target volume in order to spare normal tissue (in particular anal structures). No significant shift of the markers was found during the course of therapy. Marker matching of the EPIDs did not improve patient positioning in comparison to bone structure matching. The former position of at least one marker could be identified in all patients during histopathologic examination. The use of gold marker enables a more precise definition of the target volume for radiotherapy in patients with rectal cancer. This could eventually allow a better protection of anal structures of patients with a tumor localization = 5 cm cranial of the anal sphincter. The implantation of the gold markers improved communication between the surgeon, the radiooncologist and the pathologist resulting in intensified exchange of relevant informations. (orig.)

Gold cluster carbonyls: saturated adsorption of CO on gold cluster cations, vibrational spectroscopy, and implications for their structures.

Science.gov (United States)

Fielicke, André; von Helden, Gert; Meijer, Gerard; Pedersen, David B; Simard, Benoit; Rayner, David M

2005-06-15

We report on the interaction of carbon monoxide with cationic gold clusters in the gas phase. Successive adsorption of CO molecules on the Au(n)(+) clusters proceeds until a cluster size specific saturation coverage is reached. Structural information for the bare gold clusters is obtained by comparing the saturation stoichiometry with the number of available equivalent sites presented by candidate structures of Au(n)(+). Our findings are in agreement with the planar structures of the Au(n)(+) cluster cations with n < or = 7 that are suggested by ion mobility experiments [Gilb, S.; Weis, P.; Furche, F.; Ahlrichs, R.; Kappes, M. M. J. Chem. Phys. 2001, 116, 4094]. By inference we also establish the structure of the saturated Au(n)(CO)(m)(+) complexes. In certain cases we find evidence suggesting that successive adsorption of CO can distort the metal cluster framework. In addition, the vibrational spectra of the Au(n)(CO)(m)(+) complexes in both the CO stretching region and in the region of the Au-C stretch and the Au-C-O bend are measured using infrared photodepletion spectroscopy. The spectra further aid in the structure determination of Au(n)(+), provide information on the structure of the Au(n)(+)-CO complexes, and can be compared with spectra of CO adsorbates on deposited clusters or surfaces.

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.

Application of geophysical methods to gold prospecting in Minas de Corrales, Uruguay

International Nuclear Information System (INIS)

Costa, Antonio Flavio U.; Dias, Rogerio Aguirre; Barcelos, Andre B.B. de

1993-01-01

Geophysical methods were tested in San Gregorio gold mine, Minas de Corrales, north region of Uruguay. The ores are mainly stockworks, sheeted veinlet zones, ore shoot and disseminated sulfides types, situated in a silicated and carbonated shear zone structure, over granitic mylonites, quartz diorites, quartz-feldspathic breccia, basic rocks and quartz veins. Magnetic and radiometric methods were applied . VLF and EM34-3 detected the high resistivity silicated and carbonated zone and IP detected a weak PFE anomaly associated with pyrite/gold zone. (author)

A multivariate geostatistical methodology to delineate areas of potential interest for future sedimentary gold exploration.

Science.gov (United States)

Goovaerts, P; Albuquerque, Teresa; Antunes, Margarida

2016-11-01

This paper describes a multivariate geostatistical methodology to delineate areas of potential interest for future sedimentary gold exploration, with an application to an abandoned sedimentary gold mining region in Portugal. The main challenge was the existence of only a dozen gold measurements confined to the grounds of the old gold mines, which precluded the application of traditional interpolation techniques, such as cokriging. The analysis could, however, capitalize on 376 stream sediment samples that were analyzed for twenty two elements. Gold (Au) was first predicted at all 376 locations using linear regression (R 2 =0.798) and four metals (Fe, As, Sn and W), which are known to be mostly associated with the local gold's paragenesis. One hundred realizations of the spatial distribution of gold content were generated using sequential indicator simulation and a soft indicator coding of regression estimates, to supplement the hard indicator coding of gold measurements. Each simulated map then underwent a local cluster analysis to identify significant aggregates of low or high values. The one hundred classified maps were processed to derive the most likely classification of each simulated node and the associated probability of occurrence. Examining the distribution of the hot-spots and cold-spots reveals a clear enrichment in Au along the Erges River downstream from the old sedimentary mineralization.

Formation of gold nanorods and gold nanorod films for surface-enhanced Raman scattering spectroscopy

International Nuclear Information System (INIS)

Trotsyuk, L.L.; Kulakovich, O.S.; Shabunya-Klyachkovskaya, E.V.; Gaponenko, S.V.; Vashchenko, S.V.

2016-01-01

The formation of gold nanorods as well as thin films prepared via electrostatic deposition of gold nanorods has been investigated. The obtained gold nanorods films have been used as substrates for the surface-enhanced Raman scattering analysis of sulfur-free organic molecules mitoxantrone and malachite green as well as inorganic malachite microcrystals for the first time. The additional modification of films with L-cysteine allows one to significantly extend the use of gold nanorods for the surface-enhanced Raman scattering analysis. (authors)

Metallic gold beads in hyaluronic acid

DEFF Research Database (Denmark)

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

2013-01-01

. 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....... 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...... investigates the anti-inflammatory properties of metallic gold/HA on the gene expression of tumor necrosis factor (Tnf-α), Interleukin (Il)-1β, Il-6, Il-10, Colony-stimulating factor (Csf)-v2, Metallothionein (Mt)-1/2, Bcl-2 associated X protein (Bax) and B cell lymphoma (Bcl)-2 in cultured J774 macrophages...

GOLD predictivity mapping in French Guiana using an expert-guided data-driven approach based on a regional-scale GIS

Science.gov (United States)

Cassard, Daniel; Billa, Mario; Lambert, Alain; Picot, Jean-Claude; Husson, Yves

2008-05-01

The realistic estimation of gold mining in French Guiana requires including the numerous illegal gold washing activities in predictivity mapping. The combination of a classical approach, based on the algebraic method of Knox-Robinson and Groves, with innovative processing grid-type geochemical and radiometric data, as well as cluster analysis technique provides a better understanding of the structure of studied mineralized areas.

«By Tray, Scraper and Prokhodnushka»: Prospector’s Gold Mining Development in the Magadanskiy Sovnarhoz in 1957–1962s

Directory of Open Access Journals (Sweden)

Виталий Григорьевич Зеляк

2012-12-01

Full Text Available The author analyzes dynamics of prospector’s gold mining in the Magadanskiy sovnarhoz per 1957–1962s. It has taken the important place in regional structure of gold mining. During 1957–1959 years there was an organizational becoming artels of prospectors. The cost price of prospector’s gold was more cheaply, than on the state extraction. Regional committees of Communist party have rendered very essential support in prospector’s activity in the end of 1950 th. However party bodies have begun the company on restriction of earnings and toughening of the control over prospectors work.

Regional Standards for Rangeland Health and Guidelines for Livestock Grazing Management ... A Progress Report

OpenAIRE

1996-01-01

In August 1995, new BLM regulations for rangeland administration went into effect. The new regulations require BLM to establish regional standards for rangeland health and guidelines for grazing management. This publication is a report on the alternatives being considered for the Montana/Dakotas Rangeland Health Standards and Guidelines process.

Mercury use in small scale gold mining in Ghana: an assessment of its impact on miners

International Nuclear Information System (INIS)

Biagya, Robert Yakubu

2002-12-01

Small scale gold mining is responsible for about 5% of Ghana’s annual gold production. It is estimated that between 80,000 and 100,000 people are engaged in small scale gold mining either on part-time or permanent basis. Amalgamation is the preferred method used by small scale gold miners for extracting free gold from its ores. The rate at which mercury, an important input in this method, is discharged into the atmosphere and water bodies is alarming. This research describes the various mining and processing methods in small scale gold mining and the extent of mercury use and releases to the environment. It discusses mercury and its human and environmental effects. It defines the various forms of mercury, routes of exposure, toxic effects. The levels of exposure to mercury by all groups of small scale gold miners are determined, and the impacts on the miners and the environment are assessed. It concludes that: • Mercury is mainly released into the environment as a result of small scale gold mining through spillage of elemental mercury and evaporation of mercury from the amalgam and sponge gold when they are heated on open fire. • Mercury in environmental samples from small scale gold mining areas is well above standard limit values. • Mercury released into the environment through small scale gold mining impacts negatively on the miners themselves and the general environment. Finally, it recommends the need for the adoption of mercury emission reduction strategies for dealing with the mercury problem. (au)

Invisible gold in Colombian auriferous soils

International Nuclear Information System (INIS)

Bustos Rodriguez, H.; Oyola Lozano, D.; Rojas Martinez, Y. A.; Perez Alcazar, G. A.; Balogh, A. G.

2005-01-01

Optic microscopy, X-ray diffraction (XRD), Moessbauer spectroscopy (MS), Electron microprobe analysis (EPMA) and secondary ions mass spectroscopy (SIMS) were used to study Colombian auriferous soils. The auriferous samples, collected from El Diamante mine, located in Guachavez-Narino (Colombia), were prepared by means of polished thin sections and polished sections for EPMA and SIMS. Petrography analysis was made using an optical microscope with a vision camera, registering the presence, in different percentages, of the following phases: pyrite, quartz, arsenopyrite, sphalerite, chalcopyrite and galena. By XRD analysis, the same phases were detected and their respective cell parameters calculated. By MS, the presence of two types of pyrite was detected and the hyperfine parameters are: δ 1 = 0.280 ± 0.01 mm/s and ΔQ 1 = 0.642 ± 0.01 mm/s, δ 2 = 0.379 ± 0.01 mm/s and ΔQ 2 = 0.613 ± 0.01 mm/s. For two of the samples MS detected also the arsenopyrite and chalcopyrite presence. The mean composition of the detected gold regions, established by EPMA, indicated 73% Au and 27% Ag (electrum type). Multiple regions of approximately 200 x 200 μm of area in each mineral sample were analyzed by SIMS registering the presence of 'invisible gold' associated mainly with the pyrite and occasionally with the arsenopyrite.

Invisible gold in Colombian auriferous soils

Energy Technology Data Exchange (ETDEWEB)

Bustos Rodriguez, H., E-mail: hbustos@ut.edu.co; Oyola Lozano, D.; Rojas Martinez, Y. A. [Universidad del Tolima, Departamento de Fisica (Colombia); Perez Alcazar, G. A. [Universidad del Valle, Departamento de Fisica (Colombia); Balogh, A. G. [Darmstadt University of Technology, Institute of Materials Science (Germany)

2005-11-15

Optic microscopy, X-ray diffraction (XRD), Moessbauer spectroscopy (MS), Electron microprobe analysis (EPMA) and secondary ions mass spectroscopy (SIMS) were used to study Colombian auriferous soils. The auriferous samples, collected from El Diamante mine, located in Guachavez-Narino (Colombia), were prepared by means of polished thin sections and polished sections for EPMA and SIMS. Petrography analysis was made using an optical microscope with a vision camera, registering the presence, in different percentages, of the following phases: pyrite, quartz, arsenopyrite, sphalerite, chalcopyrite and galena. By XRD analysis, the same phases were detected and their respective cell parameters calculated. By MS, the presence of two types of pyrite was detected and the hyperfine parameters are: {delta}{sub 1} = 0.280 {+-} 0.01 mm/s and {Delta}Q{sub 1} = 0.642 {+-} 0.01 mm/s, {delta}{sub 2} = 0.379 {+-} 0.01 mm/s and {Delta}Q{sub 2} = 0.613 {+-} 0.01 mm/s. For two of the samples MS detected also the arsenopyrite and chalcopyrite presence. The mean composition of the detected gold regions, established by EPMA, indicated 73% Au and 27% Ag (electrum type). Multiple regions of approximately 200 x 200 {mu}m of area in each mineral sample were analyzed by SIMS registering the presence of 'invisible gold' associated mainly with the pyrite and occasionally with the arsenopyrite.

A study on gold detection in Wenyu gold mine with XRF techniques

International Nuclear Information System (INIS)

Liu Liuchun

1988-01-01

A portable X ray fluorescence analyzer was used for detecting fluorcescent X rays from the elements associated with gold ores. Fe, As and Ni were chosen to be the indicator elements to analyse rock samples in Wenyu gold mine. Optimum indicators were determined, and it had proved to be successful to detect gold indirectly by measuring the yields of characteristic X rays of the elements. The method provided also valuable information on geology mapping and deposits forming environment

Coal gold agglomeration: an innovative approach to the recovery of gold in environmentally sensitive areas

Energy Technology Data Exchange (ETDEWEB)

Wall, N.C.; Hughes-Narborough, C.; Willey, G. [Davy (Stockton) Ltd., Stockton-on-Tees (United Kingdom)

1994-11-01

Coal Gold Agglomeration (CGA) was developed by BP Minerals and involves the selective recovery of oleophilic gold particles from an aqueous slurry into coal-oil agglomerates. These agglomerates are allowed to build up to a high gold loading and are then separated from the slurry. The loaded agglomerates are burned and the gold is finally recovered from the ash residue by dissolution and precipitation or by direct smelting. 6 figs.

Ion beam studies of archaeological gold jewellery items

International Nuclear Information System (INIS)

Demortier, G.

1996-01-01

Analytical work on material of archaeological interest performed at LARN mainly concerns gold jewellery, with an emphasis to solders on the artefacts and to gold plating or copper depletion gilding. PIXE, RBS but also PIGE and NRA have been applied to a large variety of items. On the basis of elemental analysis, we have identified typical workmanship of ancient goldsmiths in various regions of the world: finely decorated Mesopotamian items, Hellenistic and Byzantine craftsmanship, cloisonne of the Merovingian period, depletion gilding on Pre-Colombian tumbaga. This paper is some shortening of the work performed at LARN during the last ten years. Criteria to properly use PIXE for quantitative analysis of non-homogeneous ancient artefacts presented at the 12th IBA conference in 1995 are also shortly discussed. (orig.)

Ion beam studies of archaeological gold jewellery items

Energy Technology Data Exchange (ETDEWEB)

Demortier, G [Facultes Universitaires Notre-Dame de la Paix, Namur (Belgium). Lab. d` Analyses par Reactions Nucleaires

1996-06-01

Analytical work on material of archaeological interest performed at LARN mainly concerns gold jewellery, with an emphasis to solders on the artefacts and to gold plating or copper depletion gilding. PIXE, RBS but also PIGE and NRA have been applied to a large variety of items. On the basis of elemental analysis, we have identified typical workmanship of ancient goldsmiths in various regions of the world: finely decorated Mesopotamian items, Hellenistic and Byzantine craftsmanship, cloisonne of the Merovingian period, depletion gilding on Pre-Colombian tumbaga. This paper is some shortening of the work performed at LARN during the last ten years. Criteria to properly use PIXE for quantitative analysis of non-homogeneous ancient artefacts presented at the 12th IBA conference in 1995 are also shortly discussed. (orig.).

Gold-catalyzed aerobic epoxidation of trans-stilbene in methylcyclohexane. Part I: Design of a reference catalyst

KAUST Repository

Guillois, Kevin

2012-02-01

The kinetics of the heterogeneous gold-catalyzed aerobic epoxidation of stilbene in the liquid phase has been shown to be hindered by diffusion limitations, due to the use of supports which are unsuitable to apolar reaction media. The choice of these supports is generally dictated by the ability of standard methods of preparation to stabilize highly dispersed gold nanoparticles on them. Hence, new methods need to be designed in order to produce catalytically active gold nanoparticles on hydrophobic supports in general and on passivated silicas in particular. By investigating Tsukuda\\'s method to produce colloidal solutions of gold nanoparticles upon reduction of the triphenylphosphine gold chloride complex in solution, we found that direct reduction of AuPPh3Cl in the presence of a commercially available silica support functionalized with dimethylsiloxane, Aerosil R972, leads, in a highly reproducible and potentially scalable way, to the best catalyst ever reported for this reaction. (C) 2011 Elsevier BM. All rights reserved.

Gold-catalyzed aerobic epoxidation of trans-stilbene in methylcyclohexane. Part I: Design of a reference catalyst

KAUST Repository

Guillois, Kevin; Burel, Laurence; Tuel, Alain; Caps, Valerie

2012-01-01

The kinetics of the heterogeneous gold-catalyzed aerobic epoxidation of stilbene in the liquid phase has been shown to be hindered by diffusion limitations, due to the use of supports which are unsuitable to apolar reaction media. The choice of these supports is generally dictated by the ability of standard methods of preparation to stabilize highly dispersed gold nanoparticles on them. Hence, new methods need to be designed in order to produce catalytically active gold nanoparticles on hydrophobic supports in general and on passivated silicas in particular. By investigating Tsukuda's method to produce colloidal solutions of gold nanoparticles upon reduction of the triphenylphosphine gold chloride complex in solution, we found that direct reduction of AuPPh3Cl in the presence of a commercially available silica support functionalized with dimethylsiloxane, Aerosil R972, leads, in a highly reproducible and potentially scalable way, to the best catalyst ever reported for this reaction. (C) 2011 Elsevier BM. All rights reserved.

Preparation of gold nanoparticles and determination of their particles size via different methods

Energy Technology Data Exchange (ETDEWEB)

Iqbal, Muhammad; Usanase, Gisele [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France); Oulmi, Kafia; Aberkane, Fairouz; Bendaikha, Tahar [Laboratory of Chemistry and Environmental Chemistry(LCCE), Faculty of Science, Material Science Department, University of Batna, 05000 (Algeria); Fessi, Hatem [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France); Zine, Nadia [Institut des Sciences Analytiques (ISA), Université Lyon, Université Claude Bernard Lyon-1, UMR-5180, 5 rue de la Doua, F-69100 Villeurbanne (France); Agusti, Géraldine [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France); Errachid, El-Salhi [Institut des Sciences Analytiques (ISA), Université Lyon, Université Claude Bernard Lyon-1, UMR-5180, 5 rue de la Doua, F-69100 Villeurbanne (France); Elaissari, Abdelhamid, E-mail: elaissari@lagep.univ-lyon1.fr [University of Lyon, University Lyon-1, CNRS, UMR-5007, LAGEP, F-69622 Villeurbanne (France)

2016-07-15

Graphical abstract: Preparation of gold nanoparticles via NaBH{sub 4} reduction method, and determination of their particle size, size distribution and morphology by using different techniques. - Highlights: • Gold nanoparticles were synthesized by NaBH{sub 4} reduction method. • Excess of reducing agent leads to tendency of aggregation. • The particle size, size distribution and morphology were investigated. • Particle size was determined both experimentally as well as theoretically. - Abstract: Gold nanoparticles have been used in various applications covering both electronics, biosensors, in vivo biomedical imaging and in vitro biomedical diagnosis. As a general requirement, gold nanoparticles should be prepared in large scale, easy to be functionalized by chemical compound of by specific ligands or biomolecules. In this study, gold nanoparticles were prepared by using different concentrations of reducing agent (NaBH{sub 4}) in various formulations and their effect on the particle size, size distribution and morphology was investigated. Moreover, special attention has been dedicated to comparison of particles size measured by various techniques, such as, light scattering, transmission electron microscopy, UV spectrum using standard curve and particles size calculated by using Mie theory and UV spectrum of gold nanoparticles dispersion. Particle size determined by various techniques can be correlated for monodispersed particles and excess of reducing agent leads to increase in the particle size.

Shape-controlled synthesis of NIR absorbing branched gold nanoparticles and morphology stabilization with alkanethiols

International Nuclear Information System (INIS)

Van de Broek, B; Frederix, F; Bonroy, K; Jans, H; Jans, K; Borghs, G; Maes, G

2011-01-01

Gold nanoparticles are ideal candidates for clinical applications if their plasmon absorption band is situated in the near infrared region (NIR) of the electromagnetic spectrum. Various parameters, including the nanoparticle shape, strongly influence the position of this absorption band. The aim of this study is to produce stabilized NIR absorbing branched gold nanoparticles with potential for biomedical applications. Hereto, the synthesis procedure for branched gold nanoparticles is optimized varying the different synthesis parameters. By subsequent electroless gold plating the plasmon absorption band is shifted to 747.2 nm. The intrinsic unstable nature of the nanoparticles' morphology can be clearly observed by a spectral shift and limits their use in real applications. However, in this article we show how the stabilization of the branched structure can be successfully achieved by exchanging the initial capping agent for different alkanethiols and disulfides. Furthermore, when using alkanethiols/disulfides with poly(ethylene oxide) units incorporated, an increased stability of the gold nanoparticles is achieved in high salt concentrations up to 1 M and in a cell culture medium. These achievements open a plethora of opportunities for these stabilized branched gold nanoparticles in nanomedicine.

Local structures of ionic liquids in the presence of gold under high pressures

Directory of Open Access Journals (Sweden)

Hai-Chou Chang

2013-03-01

Full Text Available The interactions between ionic liquid ([EMI][TFS] and gold surfaces have been investigated via the application of pressures up to ca. 2 GPa. Comparing the spectral features of [EMI][TFS]/gold with those of pure [EMI][TFS], no appreciable changes of C-H bands in the presence of gold powders were observed under ambient pressure. Nevertheless, the imidazolium C-H bands display red shifts in frequency as the [EMI][TFS] / Au mixture was compressed to the pressure above 1.4 GPa and a new alkyl C-H band at ca. 3016 cm−1 was also revealed. These spectral changes, being related to the addition of gold powders and pressure elevation, should be attributed to the local structural changes of C-H groups caused by pressure-enhanced interfacial interactions between [EMI][TFS] and Au. Gold powders tend to induce the changes in hydrogen bonding structures of imidazolium C2-H group under high pressures. The pressure-dependent spectral features in the asymmetric SO3 stretching region display band-narrowing and minor local structural changes induced by the presence of gold particles under high pressures. These observations suggest that Au powders perturb structural equilibrium of C-H groups of cations under high pressures.

Human mercury exposure associated with small-scale gold mining in Burkina Faso.

Science.gov (United States)

Tomicic, Catherine; Vernez, David; Belem, Tounaba; Berode, Michèle

2011-06-01

In Burkina Faso, gold ore is one of the main sources of income for an important part of the active population. Artisan gold miners use mercury in the extraction, a toxic metal whose human health risks are well known. The aim of the present study was to assess mercury exposure as well as to understand the exposure determinants of gold miners in Burkinabe small-scale mines. The examined gold miners' population on the different selected gold mining sites was composed by persons who were directly and indirectly related to gold mining activities. But measurement of urinary mercury was performed on workers most susceptible to be exposed to mercury. Thus, occupational exposure to mercury was evaluated among ninety-three workers belonging to eight different gold mining sites spread in six regions of Burkina Faso. Among others, work-related exposure determinants were taken into account for each person during urine sampling as for example amalgamating or heating mercury. All participants were medically examined by a local medical team in order to identify possible symptoms related to the toxic effect of mercury. Mercury levels were high, showing that 69% of the measurements exceeded the ACGIH (American Conference of Industrial Hygienists) biological exposure indice (BEI) of 35 μg per g of creatinine (μg/g-Cr) (prior to shift) while 16% even exceeded 350 μg/g-Cr. Basically, unspecific but also specific symptoms related to mercury toxicity could be underlined among the persons who were directly related to gold mining activities. Only one-third among the studied subpopulation reported about less than three symptoms possibly associated to mercury exposure and nearly half of them suffered from at least five of these symptoms. Ore washers were more involved in the direct handling of mercury while gold dealers in the final gold recovery activities. These differences may explain the overexposure observed in gold dealers and indicate that the refining process is the major source

Phosphorus-31 NMR (nuclear magnetic resonance) analysis of gold plating baths

Energy Technology Data Exchange (ETDEWEB)

Smith, R.E.

1990-01-01

This report describes the nuclear magnetic resonance (NMR) analysis of the gold plating baths in the Micro-Miniature Electronic Assembly department of Allied-Signal Inc., Kansas City Division (KCD). The baths were analyzed for phosphorylated components. In freshly prepared gold plating baths, a 50-percent aqueous solution of aminotrimethylphosphonate (ATMP) is the principal compound observed. As the bath is used in production, the ATMP breaks down and new materials (phosphate, ADMP, and AMMP) are identified. The NMR method was used to monitor the concentrations of the ATMP and breakdown products for a nine-month period. The 225-liter bath had plated approximately 100 square feet of gold during the nine-month period. These results can be used to predict the performance of baths as they are used in production. The accuracy of the analysis is 96 percent for ATMP and 92 percent for phosphate. The precision (relative standard deviation) is 5.2 percent for ATMP and 4.5 percent for phosphate. 1 ref., 5 figs., 2 tabs.

Annealing relaxation of ultrasmall gold nanostructures

Science.gov (United States)

Chaban, Vitaly

2015-01-01

Except serving as an excellent gift on proper occasions, gold finds applications in life sciences, particularly in diagnostics and therapeutics. These applications were made possible by gold nanoparticles, which differ drastically from macroscopic gold. Versatile surface chemistry of gold nanoparticles allows coating with small molecules, polymers, biological recognition molecules. Theoretical investigation of nanoscale gold is not trivial, because of numerous metastable states in these systems. Unlike elsewhere, this work obtains equilibrium structures using annealing simulations within the recently introduced PM7-MD method. Geometries of the ultrasmall gold nanostructures with chalcogen coverage are described at finite temperature, for the first time.

Fingerprinting ancient gold by measuring Pt with spatially resolved high energy Sy-XRF

International Nuclear Information System (INIS)

Guerra, M.F.; Calligaro, T.; Radtke, M.; Reiche, I.; Riesemeier, H.

2005-01-01

Trace elements of ancient gold such as Pt, give fundamental information on the circulation of the metal in the past. In the case of objects from the cultural heritage, the determination of trace elements requires non-destructive point analysis in general. These conditions and the need of good detection limits restrain the number of applicable analytical techniques. After the development of a PIXE set-up with a selective Cu or Zn filter of 75 μm and of a PIXE-XRF set-up using a primary target of As, we tested the possibilities of spatially resolved Sy-XRF to determine Pt in gold alloys. With a Zn filter, PIXE showed a detection limit of 1000 ppm in gold while PIXE-XRF lowers this detection limit down to 80 ppm. This last value being constrained by the resonant Raman effect produced on gold. In order to improve the detection limit of Pt keeping the non-destructiveness and access to point analysis, we developed an analytical protocol for XRF with synchrotron radiation at BESSY II, using the BAMline set-up. The L-lines of Pt were excited by a beam of energy above and below 11.564 keV and measured using a Si(Li) detector with a 50 μm Cu filter. A μ-beam of 100-250 μm 2 was used according to the size of the sample. The determination of the Pt content in the samples was carried out by Monte-Carlo simulation and subtraction of Au and Pt spectra obtained on pure standards. The limit of detection for Pt of 20 ppm was determined by using certified standards. The detection limits of a small set of other characteristic elements of gold were also measured using an incident energy of 33 keV

Gold grade variation and particle microchemistry in exploration pits of the Batouri gold district, SE Cameroon

Science.gov (United States)

Vishiti, A.; Suh, C. E.; Lehmann, B.; Egbe, J. A.; Shemang, E. M.

2015-11-01

The Batouri area hosts lode-gold mineralization under several-m-thick lateritic cover. Pitting to bed rock on a geochemical Au anomaly defined from previous reconnaissance soil sampling identified five horizons ranging from saprock at the base to laterite at the top. Analysis of bulk samples from each horizon by fire assay shows that most of the horizons are barren although 119 ppb and 48 ppb Au values were obtained from one laterite horizon and one saprolite horizon, respectively, from two separate pits. All the horizons were panned and particulate gold was also recovered only from these two horizons. The gold grains from both horizons are morphologically and compositionally indistinguishable with rare quartz, pyrite and galena inclusions. The grains have irregular, sub-rounded, bean to elongated shapes and they show a remarkable core-rim zonation. Electron microprobe analysis of the grains recorded high gold content in the rims (86.3-100 wt%) and along fissures within the grains (95.1-100 wt%). The cores are relatively Ag rich (11.8-14 wt% Ag) while the rims (0.63-13.7 wt% Ag, most of the values fall within the lower limit of this range) and fissures (0.03-5.02 wt% Ag) are poor in Ag. The low Ag concentration in the rims and along fissures is attributed to preferential leaching of Ag; a process recognized in gold grains and platiniferous alloys from alluvia. The core composition of the grains is similar to that of primary gold composition in the bedrock. These results show that gold in the soil is relic particulate gold derived from the primary source with no evidence of secondary gold precipitation in the weathering cycle. In all the pits no horizon was systematically enriched in gold suggesting there has been no chemical remobilization of gold in this environment. Rather the dispersion of gold here is in the particulate form. Therefore combining particulate gold features with assay data is relevant to exploration in such tropical environments.

Size fraction assaying of gold bearing rocks (for gold extraction) by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Ahmed, K.; Dampare, S.B.; Addo, M.A.; Osae, S.; Adotey, D.K.; Adomako, D.

2005-01-01

A novel method has been developed for processing and extraction of gold from gold bearing rocks for use by small-scale gold miners in Ghana. The methodology involved crushing of gold bearing hard rocks to fine particles to form a composite sample and screening at a range of sizes. Gold distribution in the composite sample was determined as a function of particle size by using Instrumental Neutron Activation Analysis. The concentrations of gold for the corresponding particle sizes were 16.4 ± 0.17mg/kg for sizes <63μm; 161± 0.75 mg/kg for 63 - 125 μm, 0.53 + 0.03 mg/kg for 125 - 250 μm, 4.66± 0.07 mg/kg for 250 - 355 μm, 1.55 ± 0.06 for 355 - 425 μm, 0.80 ± 0.008 mg/kg for 425 -1000 μm, and 1.27 + 0.05 mg/kg for 1000-2000 μm. The average gold content in a 7.127 kg composite sample based on particle size found to be 3.08 mg/kg. (au)

Gold and uranium extraction

International Nuclear Information System (INIS)

James, G.S.; Davidson, R.J.

1977-01-01

A process for extracting gold and uranium from an ore containing them both comprising the steps of pulping the finely comminuted ore with a suitable cyanide solution at an alkaline pH, acidifying the pulp for uranium dissolution, adding carbon activated for gold recovery to the pulp at a suitable stage, separating the loaded activated carbon from the pulp, and recovering gold from the activated carbon and uranium from solution

Free gold recovery by coal-oil agglomeration

Energy Technology Data Exchange (ETDEWEB)

Kotze, W.; Petersen, F.W. [Cape Technikon Cape Town (South Africa). Dept. of Chemical Engineering

2000-02-01

The gold mining industry has mainly relied upon the use of highly polluting chemicals, such as mercury and cyanide to recover gold from its ores. The Coal Gold Agglomeration (CGA) process was developed some years ago and has the advantage in that gold is recovered by a procedure which has little or no negative impact on the environment. A gold ore containing liberated gold particles is contacted with coal-oil agglomerates, whereby the gold is recovered into the coal/oil phase. Laboratory scale batch tests were performed on an artificial mixture gold slurry and gold recoveries of up to 85% were found under optimized conditions. By recycling the coal/oil phase, it was found that the gold loading onto the agglomerates was increased. Tests performed on an industrial ore yielded slightly lower gold recoveries, and X-ray Diffraction (XRD) analysis on the coal/oil phase showed that minerals other than gold were recovered into this phase. A comparative study was conducted whereby the CGA process was compared to mercury amalgamation. Gold recoveries obtained through amalgamation were 15% lower than by the agglomeration process, which indicates that this process can be considered favourably as an alternative to amalgamation. 16 refs., 2 figs., 6 tabs.

75 FR 35021 - Reliability Standards Development and NERC and Regional Entity Enforcement; Notice of Technical...

Science.gov (United States)

2010-06-21

... Standards Development and NERC and Regional Entity Enforcement; Notice of Technical Conference June 15, 2010... Technical Conference to address industry perspectives on certain issues pertaining to the development and... Electric Reliability Organization's (ERO) standards development process; communication and interactions...

Spectroscopic diagnostic of gold plasma

Energy Technology Data Exchange (ETDEWEB)

Busquet, M.

1986-06-01

Results of a simulation of a gold-aluminium alloy target irradiated by laser are presented. FCI code has been used with a processing out of LTE of atomic physics of gold and of multigroup photonics. Emission and reabsorption of gold and aluminium lines are included.

Activation analysis in gold industry

International Nuclear Information System (INIS)

Kist, A. A.

2003-01-01

Nuclear techniques and methods were, are, and will be very important for many fields of science, agriculture, industry, etc. Among other examples one can remember role of the nuclear medicine (radiotherapy and radiodiagnostic methods) or semiconductors (communication, computing, information, etc.) which industrial production has been on initial stage based on activation analysis. One of very illustrative examples is application of nuclear methods in gold industry. This is given by favorable nuclear properties of gold. Uzbekistan is one of the main producers of gold. Open-cast mining and hydro metallurgic extraction (using leaching by cyanide and sorption by ion-exchange resin) is the mostly used technology. The typical gold ores are sulfide and contain elevated concentration of As and Sb. That needs special technology of gold extraction. Importance of gold for Uzbekistan economy is a reason why for many years there are carried out studies concerning to gold production. These studies include also nuclear methods and their results are successfully used in gold industry. The present paper gives a brief overview for period of 25 years. For many reasons most of these studies were not published before completely. Despite some results are obtained decades ago we decided to present the overview as an example how nuclear methods can cover requirements of the whole process. We are trying to sort these studies according to methods and applications

Metamorphic Rock-Hosted Orogenic Gold Deposit Type as a Source of Langkowala Placer Gold, Bombana, Southeast Sulawesi

Directory of Open Access Journals (Sweden)

Arifudin Idrus

2014-06-01

Full Text Available DOI: 10.17014/ijog.v6i1.114In 2008, placer gold was discovered in Langkowala area (Bombana Regency, Southeast Sulawesi, Indonesia, and more than 60,000 traditional gold miners in the early 2009 have been operating by digging vertical pits and panning active stream sediments. The grade of placer gold ranges from 50 to 140 g/t. Local geological framework indicates that the placer gold is not related to volcanic rock-related hydrothermal gold deposit, e.g. epithermal, skarn or porphyry. This paper describes a preliminary study on possible primary deposit type as a source of the Langkowala (Bombana secondary placer gold. A field study indicates that the Langkowala (Bombana placer/paleoplacer gold is possibly related to gold-bearing quartz veins/veinlets hosted by metamorphic rocks particularly mica schist and metasediments in the area. These quartz veins/veinlets are currently recognized in metamorphic rocks at Wumbubangka Mountains, a northern flank of Rumbia Mountain Range. Sheared, segmented quartz veins/veinlets are of 2 cm to 2 m in width and contain gold in a grade varying between 2 and 61 g/t. At least, there are two generations of the quartz veins. The first generation of quartz vein is parallel to foliation of mica schist and metasediments with general orientation of N 300oE/60o; the second quartz vein generation crosscut the first quartz vein and the foliation of the wallrock. The first quartz veins are mostly sheared/deformed, brecciated, and occasionally sigmoidal, whereas the second quartz veins are relatively massive. The similar quartz veins/veinlets types are also probably present in Mendoke Mountain Range, in the northern side of Langkowala area. This primary gold deposit is called as ‘orogenic gold type’. The orogenic gold deposit could be a new target of gold exploration in Indonesia in the future.

Spectrophotometric Evaluation of Polyetheretherketone (PEEK as a Core Material and a Comparison with Gold Standard Core Materials

Directory of Open Access Journals (Sweden)

Bogna Stawarczyk

2016-06-01

Full Text Available This study investigated the colorimetric properties of different veneering materials on core materials. Standardized specimens (10 mm × 10 mm × 1.5 mm reflecting four core (polyetheretherketone (PEEK, zirconia (ZrO2, cobalt–chromium–molybdenum alloy (CoCrMo, and titanium oxide (TiO2; thickness: 1.5 mm and veneering materials (VITA Mark II, IPS e.max CAD, LAVA Ultimate and VITA Enamic, all in shade A3; thickness: 0.5, 1.0, 1.5 and 2 mm, respectively were fabricated. Specimens were superimposed to assemblies, and the color was determined with a spectrophotometer (CieLab-System or a chair-side color measurement device (VITA EasyShade, respectively. Data were analyzed using three-, two-, and one-way ANOVA, a Chi2-test, and a Wilson approach (p < 0.05. The measurements with EasyShade showed A2 for VITA Mark II, A3.5 for VITA Enamic, B2 for LAVA Ultimate, and B3 for IPS e.max CAD. LabE-values showed significant differences between the tested veneering materials (p < 0.001. CieLab-System and VITA EasyShade parameters of the different assemblies showed a significant impact of core (p < 0.001, veneering material (p < 0.001, and thickness of the veneering material (p < 0.001. PEEK as core material showed comparable outcomes as compared to ZrO2 and CoCrMo, with respect to CieLab-System parameters for each veneering material. The relative frequency of the measured VITA EasyShade parameters regarding PEEK cores also showed comparable results as compared to the gold standard CoCrMo, regardless of the veneering material used.

75 FR 65964 - Version One Regional Reliability Standard for Resource and Demand Balancing

Science.gov (United States)

2010-10-27

... this record and, thus, does not persuade us.\\35\\ \\33\\ WECC's analysis shows that, over the past 15... notes that the currently approved regional Reliability Standard was established through negotiations in...

78 FR 35149 - Addresses of Regional Offices

Science.gov (United States)

2013-06-12

..., and Texas), 500 Gold Avenue SW., Room 9018 (P.O. Box 1306), Albuquerque, New Mexico 87102. (c) Midwest... 01035. (f) Mountain-Prairie Regional Office (Region 6--comprising the States of Colorado, Kansas...

Medicinal gold compounds

International Nuclear Information System (INIS)

Parish, R.V.; Cottrill, S.M.

1987-01-01

A major use of gold compounds in the pharmaceutical industry is for anti-arthritic agents. The disease itself is not understood and little is known about the way in which the drugs act, but detailed pictures of the distribution of gold in the body are available, and some of the relevant biochemistry is beginning to emerge. The purpose of this article is to give a survey of the types of compounds presently employed in medicine, of the distribution of gold in the body which results from their use, and of some relevant chemistry. Emphasis is placed on results obtained in the last few years

Spectroscopic diagnostic of gold plasma

International Nuclear Information System (INIS)

Busquet, M.

1986-01-01

Results of a simulation of a gold-aluminium alloy target irradiated by laser are presented. FCI code has been used with a processing out of LTE of atomic physics of gold and of multigroup photonics. Emission and reabsorption of gold and aluminium lines are included [fr

Application of K0-NAA in the Determination of Gold and other Trace Elements in Mineralized Rocks from El-Sid Gold District, Eastern Desert, Egypt

International Nuclear Information System (INIS)

El Abd, A.; Hamdy, M.; Mostafa, M.; El-Amir, M.

2009-01-01

K 0 - neutron activation analysis is an important method for multi-element analysis . The NAA k - 0 was used to determine the concentration of gold and some other trace elements in the mineralized mafic (gabro) and ultramafic (serpentinite) rocks from El-Sid gold district, Central Eastern Desert, Egypt . The samples were properly prepared together with the standards Au, Zr and Ni and simultaneously irradiated in the irradiation position 2, which is characterized with the neutron spectrum parameters a = -0.01 and f =20. After activation, the samples were subjected to gamma-ray spectrometry, using a high-purity germanium detection system and computerized multichannel analyzer. The concentrations of 25 elements, beside gold were determined. The results showed that the concentrations of incompatible elements including rare earth elements, large-ion lithophile elements (Rb, Sr, Th, Ba, Cs and Na) and high field strength elements (Ta, Hf and Zr), and the compatible elements (transition elements Co and Cr) are different from one sample to another. The results were briefly discussed within the text of this research work.

Combined photothermo-chemotherapy using gold nanoshells on drug-loaded micelles for colorectal cancer treatment

Science.gov (United States)

Lee, Shin-Yu; Shieh, Ming-Jium

2018-02-01

Combined photothermo-chemotherapy is a new strategy for cancer treatment which improves the therapeutic outcome by synergistic effects of both therapies. Here, we presented a multifunctional gold nanoshell that exhibited excellent photothermal conversion and delivered the hydrophobic chemotherapy drug, SN-38. The positively charged SN-38-loaded PDMA-PCL micelles were decorated with a gold layer by in situ reduction of chloroauric acid on the surface of micelles. Scanning and transmission electron microscopy images proved micelles were successfully decorated and the resulting gold nanoshells had a spherical morphology with a narrow size distribution. The synthesized gold nanoshells displayed a broad surface plasmon resonance peak in the near-infrared wavelength region and a great photothermal conversion ability. After pegylation, gold nanoshells were stable in biological media and appeared highly biocompatible in the absence of laser irradiation. Upon near-infrared laser irradiation, incident energy was converted into heat by gold nanoshells on SN-38-loaded micelles (SN-38@pGNS), which causes local temperature increase and triggers the release of encapsulated drug. Compared to SN-38, SN-38-loaded micelles, or laser with drug-free gold nanoshells alone, combined photothermo-chemotherapy using SN-38@pGNS with laser irradiation killed colorectal cancer cells with higher efficacy in vitro and demonstrated significant tumor suppression in vivo, suggesting that gold nanoshells on drug-loaded micelles delivered SN-38 and photothermal therapy in synergistic actions and might be a potential candidate for future colorectal cancer therapy.

Separation and enrichment of gold(III) from environmental samples prior to its flame atomic absorption spectrometric determination

Energy Technology Data Exchange (ETDEWEB)

Senturk, Hasan Basri; Gundogdu, Ali [Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Bulut, Volkan Numan [Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 28049 Giresun (Turkey); Duran, Celal [Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey); Soylak, Mustafa [Department of Chemistry, Faculty of Arts and Sciences, Erciyes University, 38039 Kayseri (Turkey)], E-mail: soylak@erciyes.edu.tr; Elci, Latif [Department of Chemistry, Faculty of Arts and Sciences, Pamukkale University, 20020 Denizli (Turkey); Tufekci, Mehmet [Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey)

2007-10-22

A simple and accurate method was developed for separation and enrichment of trace levels of gold in environmental samples. The method is based on the adsorption of Au(III)-diethyldithiocarbamate complex on Amberlite XAD-2000 resin prior to the analysis of gold by flame atomic absorption spectrometry after elution with 1 mol L{sup -1} HNO{sub 3} in acetone. Some parameters including nitric acid concentration, eluent type, matrix ions, sample volume, sample flow rate and adsorption capacity were investigated on the recovery of gold(III). The recovery values for gold(III) and detection limit of gold were greater than 95% and 16.6 {mu}g L{sup -1}, respectively. The preconcentration factor was 200. The relative standard deviation of the method was <6%. The adsorption capacity of the resin was 12.3 mg g{sup -1}. The validation of the presented procedure was checked by the analysis of CRM-SA-C Sandy Soil certified reference material. The presented procedure was applied to the determination of gold in some environmental samples.

Novel solid phase extraction procedure for gold(III) on Dowex M 4195 prior to its flame atomic absorption spectrometric determination

Energy Technology Data Exchange (ETDEWEB)

Tuzen, Mustafa [Gaziosmanpasa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey)], E-mail: mtuzen@gop.edu.tr; Saygi, Kadriye O. [Gaziosmanpasa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey); Soylak, Mustafa [Erciyes University, Faculty of Science and Arts, Chemistry Department, 38039 Kayseri (Turkey)

2008-08-15

A method for solid phase extraction (SPE) of gold(III) using Dowex M 4195 chelating resin has been developed. The optimum experimental conditions for the quantitative sorption of gold(III), pH, effect of flow rates, eluent types, sorption capacity and the effect of diverse ions on the sorption of gold(III) have been investigated. The chelating resin can be reused for more than 100 cycles of sorption-desorption without any significant change in sorption of gold(III) ions. The recovery values for gold(III) and detection limit (LOD) of gold were greater than 95% and 1.61 {mu}g L{sup -1}, respectively. The preconcentration factor was 31. The relative standard deviation of the method was <5%. The adsorption capacity of the resin was 8.1 mg g{sup -1}. The proposed method has been applied for the determination of gold(III) in some real samples including water, soil and sediment samples.

Occupational and environmental mercury exposure among small-scale gold miners in the Talensi-Nabdam District of Ghana's Upper East region.

Science.gov (United States)

Paruchuri, Yasaswi; Siuniak, Amanda; Johnson, Nicole; Levin, Elena; Mitchell, Katherine; Goodrich, Jaclyn M; Renne, Elisha P; Basu, Niladri

2010-11-15

Mercury use in small-scale gold mining is ubiquitous across Ghana but little is known about the extent to which such activities have contaminated community residents and miners. Here, occupational exposures to elemental mercury (via urine sampling) and dietary exposures to methylmercury (via hair sampling) were assessed among 120 participants recruited from a mining community located in the Talensi-Nabdam District of Ghana's Upper East region during summer 2009. More than one-fifth of the participants had moderately high levels of urinary mercury (>10μg/L) and 5% had urine mercury levels that exceeded the WHO guideline value of 50μg/L. When participants were stratified according to occupation, those active in the mining industry had the highest mercury levels. Specifically, individuals that burned amalgam had urine mercury levels (median: 43.8μg/L; mean ± SD: 171.1±296.5μg/L; n=5) significantly higher than median values measured in mechanical operators (11.6μg/L, n=4), concession managers/owners (5.6μg/L, n=11), excavators that blast and chisel ore (4.9μg/L, n=33), individuals that sift and grind crushed ore (2.2μg/L, n=47), support workers (0.5μg/L, n=14), and those with no role in the mining sector (2.5μg/L, n=6). There was a significant positive Spearman correlation between fish consumption and hair mercury levels (r=0.30) but not with urine mercury (r=0.18) though further studies are needed to document which types of fish are consumed as well as portion sizes. Given that 200,000 people in Ghana are involved in the small-scale gold mining industry and that the numbers are expected to grow in Ghana and many other regions of the world, elucidating mercury exposure pathways in such communities is important to help shape policies and behaviors that may minimize health risks. Copyright © 2010 Elsevier B.V. All rights reserved.

Antimicrobial activity of silver and gold in toothpastes: A comparative analysis.

Science.gov (United States)

Junevičius, Jonas; Žilinskas, Juozas; Česaitis, Kęstutis; Česaitienė, Gabrielė; Gleiznys, Darius; Maželienė, Žaneta

2015-01-01

In this study, we compared the antimicrobial activity of identical toothpastes differing only in silver or gold nanoparticles against the activity of one of the common toothpastes containing a chemical active ingredient. We also compared the active concentrations of the toothpastes. For this study, we selected "Royal Denta" toothpastes containing silver and gold particles, and the "Blend-A-Med Complete" toothpaste containing zinc citrate as the active ingredient. We used 8 standard microorganism cultures on the basis of their individual mechanisms of protection. The antimicrobial activity of each studied preparation was evaluated at 9 concentrations. Most effective against gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis) was the "Silver Technology" – MIC was 0.004-0.0015 g/mL. Neither "Silver Technology" nor "Orange and Gold Technology" had any effect on Escherichia coli or Proteus mirabilis. Antimicrobial activity against the motile bacterium Proteus mirabilis was observed in "Silver Technology", "Orange and Gold Technology", and "Blend-A-Med Complete" – the MIC was 0.015 g/mL or lower. No antimicrobial activity against Candida albicans fungus at the studied concentrations was observed in the "Orange and Gold Technology". The toothpaste "Blend-A-Med" demonstrated the most effective antimicrobial activity - the MIC of 0.0015 g/mL and 0.015 g/mL inhibited Staphylococcus aureus and Enterococcus faecalis, respectively, and the MIC of 0.15 g/mL inhibited the growth of the bacteria Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, and fungus Candida albicans. Silver in toothpaste has a greater antimicrobial effect than gold, but its effect is still inferior to that of a chemical antimicrobial agent.

GOLD MINERAL PROSPECTING USING PHASED ARRAY TYPE L-BAND SYNTHETIC APERTURE RADAR (PALSAR SATELLITE REMOTE SENSING DATA, CENTRAL GOLD BELT, MALAYSIA

Directory of Open Access Journals (Sweden)

A. Beiranvand Pour

2016-06-01

Full Text Available The Bentong-Raub Suture Zone (BRSZ of Peninsular Malaysia is one of the significant structural zones in Sundaland, Southeast Asia. It forms the boundary between the Gondwana-derived Sibumasu terrane in the west and Sukhothai arc in the east. The BRSZ is also genetically related to the sediment-hosted/orogenic gold deposits associated with the major lineaments and form-lines in the central gold belt Central Gold Belt of Peninsular Malaysia. In tropical environments, heavy tropical rainforest and intense weathering makes it impossible to map geological structures over long distances. Advances in remote sensing technology allow the application of Synthetic Aperture Radar (SAR data in geological structural analysis for tropical environments. In this investigation, the Phased Array type L-band Synthetic Aperture Radar (PALSAR satellite remote sensing data were used to analyse major geological structures in Peninsular Malaysia and provide detailed characterization of lineaments and form-lines in the BRSZ, as well as its implication for sediment-hosted/orogenic gold exploration in tropical environments. The major geological structure directions of the BRSZ are N-S, NNE-SSW, NE-SW and NW-SE, which derived from directional filtering analysis to PALSAR data. The pervasive array of N-S faults in the study area and surrounding terrain is mainly linked to the N-S trending of the Suture Zone. N-S striking lineaments are often cut by younger NE-SW and NW-SE-trending lineaments. Gold mineralized trends lineaments are associated with the intersection of N-S, NE-SW, NNW-SSE and ESE-WNW faults and curvilinear features in shearing and alteration zones. Lineament analysis on PALSAR satellite remote sensing data is a useful tool for detecting the boundary between the Gondwana-derived terranes and major geological features associated with suture zone especially for large inaccessible regions in tropical environments.

Transient extracellular application of gold nanostars increases hippocampal neuronal activity.

Science.gov (United States)

Salinas, Kirstie; Kereselidze, Zurab; DeLuna, Frank; Peralta, Xomalin G; Santamaria, Fidel

2014-08-20

With the increased use of nanoparticles in biomedical applications there is a growing need to understand the effects that nanoparticles may have on cell function. Identifying these effects and understanding the mechanism through which nanoparticles interfere with the normal functioning of a cell is necessary for any therapeutic or diagnostic application. The aim of this study is to evaluate if gold nanoparticles can affect the normal function of neurons, namely their activity and coding properties. We synthesized star shaped gold nanoparticles of 180 nm average size. We applied the nanoparticles to acute mouse hippocampal slices while recording the action potentials from single neurons in the CA3 region. Our results show that CA3 hippocampal neurons increase their firing rate by 17% after the application of gold nanostars. The increase in excitability lasted for as much as 50 minutes after a transient 5 min application of the nanoparticles. Further analyses of the action potential shape and computational modeling suggest that nanoparticles block potassium channels responsible for the repolarization of the action potentials, thus allowing the cell to increase its firing rate. Our results show that gold nanoparticles can affect the coding properties of neurons by modifying their excitability.

Mercury Distribution in the Processing of Jatiroto Gold Mine Wonogiri Central Java Indonesia

Science.gov (United States)

Fitri Yudiantoro, Dwi; Nurcholis, Muhammad; Sri Sayudi, Dewi; Abdurrachman, Mirzam; Paramita Haty, Intan; Pambudi, Wiryan; Subroborini, Arum

2017-06-01

The research area is one of the Wonogiri gold producer. In this region there are nearly 30 gold processing locations. This area has a steep morphology which is part of Mt. Mas. The work of the gold processing is a part time job besides for the local farmer population. To get the gold bearing rocks, are by digging holes manually around Mt. Mas, while gold processing is carried out in their homes. As a result of these activities, then identified the distribution of mercury in the surrounding settlements. Analytical methods used in this study is the measurement mercury content using Hg meter on altered rocks, soil and using XRF (X-Ray Fluorescence) for plant samples. This results of research shows that there are conducted on mercury contents in the altered rocks, soil and plants showed significant mercury contents in altered rocks, soil and plants. This proves that mercury has polluted the environment surrounding residents, both of people living in the hill down on the lower plain areas. The results of this study are expected to be used as reference to help overcome the pollution of the area.

Spherical aggregates composed of gold nanoparticles

International Nuclear Information System (INIS)

Chen, C-C; Kuo, P-L; Cheng, Y-C

2009-01-01

Alkylated triethylenetetramine (C12E3) was synthesized and used as both a reductant in the preparation of gold nanoparticles by the reduction of HAuCl 4 and a stabilizer in the subsequent self-assembly of the gold nanoparticles. In acidic aqueous solution, spherical aggregates (with a diameter of about 202 ± 22 nm) of gold nanoparticles (with the mean diameter of ∼18.7 nm) were formed. The anion-induced ammonium adsorption of the alkylated amines on the gold nanoparticles was considered to provide the electrostatic repulsion and steric hindrance between the gold nanoparticles, which constituted the barrier that prevented the individual particles from coagulating. However, as the amino groups became deprotonated with increasing pH, the ammonium adsorption was weakened, and the amino groups were desorbed from the gold surface, resulting in discrete gold particles. The results indicate that the morphology of the reduced gold nanoparticles is controllable through pH-'tunable' aggregation under the mediation of the amino groups of alkylated amine to create spherical microstructures.

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...

Omentoplasty in Perforated Peptic Ulcer Surgery: Is it Still the Gold ...

African Journals Online (AJOL)

multiruka1

the stimulus for fibrin formation. Very often surgeons mention „using a Graham patch‟, but what they actually. Omentoplasty in Perforated Peptic Ulcer Surgery: Is it Still the Gold Standard? Paul Ochieng‟ Odula. School of Medicine, University of Nairobi. Correspondence to: Dr. Paul Odula, P.O. Box 19762 – 00202, Nairobi, ...

Chiral supramolecular gold-cysteine nanoparticles: Chiroptical and nonlinear optical properties

Directory of Open Access Journals (Sweden)

Isabelle Russier-Antoine

2016-10-01

Full Text Available Cysteine is a sulfur-containing amino acid that easily coordinates to soft metal ions and grafts to noble metal surfaces. We report a simple synthetic approach for the production of chiral gold-cysteine polymeric nanoparticles soluble in water. Conjugation of cysteine with gold in a polymeric way, leading to ~50 nm diameter nanoparticles, resulted in the generation of new characteristic circular dichroism (CD signals in the region of 250–400 nm, whereas no CD signal changes were found with cysteine alone. We also investigate their nonlinear optical properties after two-photon absorption. Two-photon emission spectra and first hyper-polarizabilities, as obtained by the hyper-Rayleigh scattering technique, of these particles are presented.

The free electron laser: a system capable of determining the gold standard in laser vision correction

International Nuclear Information System (INIS)

Fowler, W. Craig; Rose, John G.; Chang, Daniel H.; Proia, Alan D.

1999-01-01

Introduction. In laser vision correction surgery, lasers are generally utilized based on their beam-tissue interactions and corneal absorption characteristics. Therefore, the free electron laser, with its ability to provide broad wavelength tunability, is a unique research tool for investigating wavelengths of possible corneal ablation. Methods. Mark III free electron laser wavelengths between 2.94 and 6.7 μm were delivered in serial 0.1 μm intervals to corneas of freshly enucleated porcine globes. Collateral damage, ablation depth, and ablation diameter were measured in histologic sections. Results. The least collateral damage (12-13 μm) was demonstrated at three wavelengths: 6.0, 6.1 (amide I), and 6.3 μm. Minimal collateral damage (15 μm) was noted at 2.94 μm (OH-stretch) and at 6.2 μm. Slightly greater collateral damage was noted at 6.45 μm (amide II), as well as at the 5.5-5.7 μm range, but this was still substantially less than the collateral damage noted at the other wavelengths tested. Conclusions. Our results suggest that select mid-infrared wavelengths have potential for keratorefractive surgery and warrant additional study. Further, the free electron laser's ability to allow parameter adjustment in the far-ultraviolet spectrum may provide unprecedented insights toward establishing the gold-standard parameters for laser vision correction surgery

Histopathological examination of nail clippings using PAS staining (HPE-PAS): gold standard in diagnosis of Onychomycosis.

Science.gov (United States)

Jeelani, Shazia; Ahmed, Qazi Masood; Lanker, Audil Mohmad; Hassan, Iffat; Jeelani, Nasir; Fazili, Tawheeda

2015-01-01

Onychomycosis is fungal infection of one or more of the nail units. However, because fungi cause only about half of all nail dystrophies, the use of appropriate diagnostic techniques is important to ensure correct diagnosis and treatment. Aim of the present study was to compare direct microscopy, culture and HPE-PAS for diagnosis of onychomycosis by evaluating their sensitivity and various other relevant statistical parameters. A prospective, hospital-based, cross-sectional study was conducted on 216 patients with a high degree of clinical suspicion of onychomycosis. Nail specimens were evaluated using three diagnostic methods, i.e. direct microscopy using 20% Potassium hydroxide (KOH) & 40% Di-methyl-suphoxide (DMSO), culture and histopathological examination using PAS stain (HPE-PAS). Of 216 patients direct microscopy was positive in 138 (63.9%), culture in 147 (68%) and HPE-PAS in 164 patients (76%). One hundred and seventy-nine patients fitted into the criteria set for confirmed diagnosis of onychomycosis. Using this as a denominator; direct microscopy, culture and HPE-PAS had sensitivities of 77.1%, 70% and 91.6% respectively. Also, HPE-PAS showed the highest sensitivity of 94.7% in 19 cases with prediagnostic antimycotic treatment compared to direct microscopy (42.1%) or culture (57.9%). HPE-PAS shows high sensitivity for diagnosis of onychomycosis and can be considered as a gold standard in the diagnosis of onychomycosis. © 2014 Blackwell Verlag GmbH.

Poly-thiosemicarbazide Membrane for Gold Adsorption and In-situ Growth of Gold Nanoparticles

KAUST Repository

Parra, Luis F.

2012-12-01

In this work the synergy between a polymer containing chelate sites and gold ions was explored by the fabrication of a polymeric membrane with embedded gold nanoparticles inside its matrix and by developing a process to recover gold from acidic solutions. After realizing that the thiosemicarbazide groups present in the monomeric unit of poly-thiosemicarbazide (PTSC) formed strong complexes with Au ions, membrane technology was used to exploit this property to its maximum. The incorporation of metal nanoparticles into polymeric matrices with current technologies involves either expensive and complicated procedures or leads to poor results in terms of agglomeration, loading, dispersion, stability or efficient use of raw materials. The fabrication procedure described in this thesis solves these problems by fabricating a PTSC membrane containing 33.5 wt% in the form of 2.9 nm gold nanoparticles (AuNPs) by a three step simple and scalable procedure. It showed outstanding results in all of the areas mentioned above and demonstrated catalytic activity for the reduction of 4-Nitrophenol (4−NP) to 4-Aminophenol (4−AP). The current exponential demand of gold for electronics has encouraged the development of efficient processes to recycle it. Several adsorbents used to recover gold from acidic solutions can be found in the literature with outstanding maximum uptakes,yet, poor kinetics leading to an overall inefficient process. The method developed in this dissertation consisted in permeating the gold-containing solution through a PTSC membrane that will capture all the Au ions by forming a metal complex with them. Forcing the ions through the pores of the membrane eliminates the diffusion limitations and the adsorption will only depended on the fast complexation kinetics, resulting in a very efficient process. A flux as high as 1868 L/h m2 was enough to capture >90% of the precious metal present in a solution of 100 ppm Au. The maximum uptake achieved without sacrificing

Some Observations on Gold in the Weathering Profile at Garimpo Porquinho, an Artisanal Mine in the Tapajós Region, Brazilian Amazon

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