WorldWideScience

Sample records for century colorado silver

  1. A Defense of the Late Nineteenth Century White Suffrage Activists of Australia, New Zealand and Colorado

    OpenAIRE

    Theodora-Eliza Vacarescu

    2003-01-01

    This paper addresses the history of late nineteenth century women’s suffrage and the history of the women involved in the struggle for female enfranchisement of Australia, New Zealand, and Colorado, which have recently been the target of fervent postcolonial criticism. The paper will attempt to defend the efforts of white suffragists by deconstructing the groundlessness and, occasion- ally, the falseness of postcolonial criticism.

  2. Isotopic Ag–Cu–Pb record of silver circulation through 16th–18th century Spain

    Science.gov (United States)

    Desaulty, Anne-Marie; Telouk, Philippe; Albalat, Emmanuelle; Albarède, Francis

    2011-01-01

    Estimating global fluxes of precious metals is key to understanding early monetary systems. This work adds silver (Ag) to the metals (Pb and Cu) used so far to trace the provenance of coinage through variations in isotopic abundances. Silver, copper, and lead isotopes were measured in 91 coins from the East Mediterranean Antiquity and Roman world, medieval western Europe, 16th–18th century Spain, Mexico, and the Andes and show a great potential for provenance studies. Pre-1492 European silver can be distinguished from Mexican and Andean metal. European silver dominated Spanish coinage until Philip III, but had, 80 y later after the reign of Philip V, been flushed from the monetary mass and replaced by Mexican silver. PMID:21606351

  3. Epilepsy on the silver screen in the 21st century.

    Science.gov (United States)

    Baxendale, Sallie

    2016-04-01

    Epilepsy remains an attractive vehicle for filmmakers in the twenty-first century. This review examines the themes of twenty-one films, released between 2000 and 2014, that feature a character with epilepsy or a pivotal scene involving a seizure. Epilepsy continues to be associated with the supernatural in modern cinematic output. Demonic possession and epilepsy now share a similar cinematic lexicon. Unfortunately, the overlap is more than just visual. Supernatural treatments of narratives that claim to be 'based on a true story' of someone with epilepsy continue to blur the lines between medical and spiritual realms. Although there has been a steady progression away from concealment of the condition, epilepsy continues to signal 'otherness' in movie characters and seldom in a good way. All too often, a character has epilepsy to maximize the unease of the audience with them; it is a device that is used to signal 'this character is not like you'. However, amongst the hackneyed negative stereotypes, accurate portrayals of the condition are beginning to emerge, not least due to active collaborations between filmmakers and epilepsy advocacy groups. Far from being worthy, it is heartening that these films are also those that are the most absorbing and thought-provoking of the cinematic output thus far this century. This article is part of a Special Issue entitled "Epilepsy, Art, and Creativity". PMID:26907968

  4. Colorado

    Directory of Open Access Journals (Sweden)

    Gerardo Rodríguez Quiroz

    2008-01-01

    Full Text Available La conservación de la biodiversidad cuenta, entre sus principales mecanismos de intervención, con las áreas naturales protegidas. En el alto Golfo de California (AGC se ubica la Reser-va de la Biosfera del Alto Golfo de California y Delta del Río Colorado, en la que subsisten especies de alto valor económico, así como especies en peligro de extinción. Este último factor justificó el establecimiento de la reserva. El estudio analiza la efectividad de la Reserva del Alto Golfo como mecanismo de protección de los recursos naturales, en particular de las que están en riesgo de desaparecer, así como de comprobar si los pescadores han mejorado sus condiciones de vida tras la operación de esa área natural. La exploración se llevó a cabo mediante la aplicación de una encuesta a los pescadores. Se sugiere que es indispensable un gran esfuerzo, de autoridades y grupos organizados, para encontrar soluciones al manejo de la Reserva, a fin fijar un programa que permita la recuperación de las especies en peligro de extinción, elevar la calidad de vida de los pescadores y con ello garantizar un equilibrio entre la conservación y la sustentabilidad de la pesca y de los pescadores en el Alto Golfo de California.

  5. Compositional study of IIIrd century BC silver coins from Kreshpan hoard (Albania) using EDXRF spectrometry

    International Nuclear Information System (INIS)

    The elemental composition of 122 silver coins from a hoard of the 3rd century BC, minted by the Illyrian king Monounios and the ancient cities of Dyrrachion and Korkyra was determined by EDXRF. The results showed that the different groups of coins were made of a similar Ag-Cu alloy with Ag concentration in the range 94-98%. The examination of the contents of minor elements Pb, Au and Bi showed that the coins minted by the Illyrian king Monounios have similar composition with the largest part of Dyrrachion coins and those from Korkyra. On the other side, two subgroups containing different amounts of Au and Bi can be observed within the general group of coins minted in Dyrrachion

  6. The distribution of silver specimens from the Kongsberg Silver Mines, Norway, 17th and 18th centuries

    NARCIS (Netherlands)

    Berg, B.I.; Nordrum, F.S.

    2004-01-01

    Specimens of native silver from the Kongsberg mines in Norway are world famous and have been distributed through sales and gifts during the whole period of mining from 1623 to 1958. Names of customers, the number of sold specimens and their silver content are documented in accounts which are preserv

  7. Study of a 9th century silver earrings set from Mikulčice: corrosion, conservation and maintenance

    OpenAIRE

    Cardoso, Mariana Oliveira

    2010-01-01

    The presented study deal with the degradation processes of the silver objects, buried for a long time in human graves and with their appropriate methods of conservation and restoration after excavation during archaeological research. It was used for this study a set of earrings from the 9th century A.D. found in Mikulčice, in the southeast of Czech Republic. To understand the mechanisms and process of corrosion and the manufacture and decoration techniques of the earrings was perform...

  8. Greek silver drachmae of the roman civil war period, (first century BC) as reflected in external beam PIXE analysis

    International Nuclear Information System (INIS)

    The great number of Greek silver coins from the first century BC found in the Balkan - Carpathian region have aroused a sharp interest among numismatic researchers. The problem is to classify these coins - tetradrachmae of Thasos and drachmae of Apollonia and Dyrrachium into originals, copies and imitations, in relation to their provenance. Well known are Celtic Thasos tetradrachmae copies (good quality coins), and also Barbarian imitations (absence or misspelling of the legend, disproportionate and simplified figures). Thracians, Dacians and Celts used to produce the same type of coins. The dies used for coining were bought or stolen from the Greeks, while some local engravers manufactured their own dies. Visual examination, the first step of a numismatist's work, is insufficient to classify the coins. This is the reason why elemental analysis is required (X-Ray Fluorescence and Proton Induced X-ray Emission methods). 36 Thasos tetradrachmae and 145 Apollonia and Dyrrachium drachmae, struck between 60 and 48 BC, a very intense period of civil Roman wars, belonging to Tarii Crisurilor Museum in Oradea and to Budapest National Museum were analyzed. The fingerprint of the third group of Thasian tetradrachmae is the bromine. The presence of this element in silver coins is mentioned in the literature, where bromine is linked to marine spray (the hoard was found near the seacoast). In our case, the coins were found in a region far away from the Black Sea coast. Taking into account the presence of bromine in silver ore from the Transylvania mine Rodna and supposing an imperfect procedure of refinement , these coins could be attributed to local workshops. As for the Apollonia and Dyrrachium drachmae, a similar situation can be retraced. Because of the high silver content and refined aspect of the coins belonging to the first group, one can assume that these drachmae are the original ones, minted of Macedonian silver. The percentage of copper in the second group of coins

  9. Changes in the relationships between climate and silver fir (Abies alba Mill.) growth during the 20th century in the Tuscan Apennine Alps (Middle Italy)

    Science.gov (United States)

    D'Aprile, F.; Tapper, N.; Baker, P.; Bartolozzi, L.; Bottacci, A.

    2012-04-01

    In the Tuscan Apennine Alps, recent research has shown that similarity in trends of monthly climate variables (i.e., temperature and rainfall) is non-stationary amongst sites during the 20th century even between sites that differ little in elevation and at a relatively short distance from each other (D'Aprile et al., 2010; D'Aprile et al., 2011). Moreover, the level of correlation between series of monthly climate variables varies irregularly from highly positive to negative over time. We hypothesised that those changing climate conditions, even at the local level, could cause different tree-ring growth responses in silver fir amongst sites. The hypothesis was tested by dendroclimatological analysis, which was applied to study stands in silver fir forests close to the meteorological stations where climate analysis has been made. Results show that the influences of both monthly mean temperature and monthly rainfall on silver fir growth vary greatly during the 20th century in the Tuscan Apennine Alps, and the ways that they change differ with month and amongst sites. Within sites, differences in the relationships between climate variables and silver fir tree-ring growth appear small in spite of different elevation of the study stands. These results contribute a changing point in forest planning and management especially in consideration of the need to adapt forest management and interventions to changing climate conditions and mitigate the impacts on silver fir forests. Moreover, they introduce climate variability as a key parameter in sustainable forest management for biodiversity conservation, socially responsible uses, nature conservation, and survival of the only conifer tree species typical of mountain mixed forest ecosystems in the Apennine Alps.

  10. Adulterations in first century BC: the case of Greek silver drachmae analyzed by X-ray methods

    International Nuclear Information System (INIS)

    For coins, chemical differences that occur during preparation affect the elemental composition and can be used to identify the producing technologies and workshops and to distinguish between originals and counterfeits. In this study, we focus our attention on some Thassos silver tetradrachmae and on an important number of Apollonia-Dyrrhachium silver drachmae emitted by these Greek cities under Pompejus authority during the First Roman Civil War. All the analyzed coins were found on the territory of present Romania (ancient Dacia). The important presence of Apollonia-Dyrrhachium drachmae here can be explained by the hypothesis that these coins were probably used by Pompejus as payment for Dacian mercenaries. To analyze the elemental composition we used: 241Am gamma source based X-ray fluorescence and in vacuum 3 MeV protons particle induced X-ray emission. The following main categories were found: original coins, local (Barbarian) imitations, debased coins with silver content down to 70%, official (original dies) counterfeits of bronze, official counterfeits of tin, and plated coins--a bronze core covered by a 0.2-0.5 mm silver layer

  11. An estimate of the minting method of three silver coins of the 3rd century B.C. through their microstructural study

    Energy Technology Data Exchange (ETDEWEB)

    Pistofidis, N.; Vourlias, G. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki (Greece); Dilo, T. [Department of Physics, FNSc, University of Tirana, Tirana (Albania); Civici, N. [Department of Spectroscopy, Institute of Nuclear Physics, Tirana (Albania); Gjongecaj, Sh. [Department of Antiquity, Institute of Archaeology, Tirana (Albania); Skolianos, S. [Physical Metallurgy Laboratory, Department of mechanical Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki (Greece); Polychroniadis, E.K., E-mail: polychr@auth.g [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki (Greece)

    2010-05-01

    The microstructure of three silver coins of the 3rd century B.C. from the Illyrian King Monounios and the ancient Greek cities of Dyrrachion and Corcyra, belonging to the Kreshpan hoard, was determined with X-ray diffraction and transmission electron microscopy in order to investigate their minting method. It is deduced that the coins are characterized by a large number of structural defects, mainly dislocations, twins and microtwins, which in some cases were bent. These crystal defects are common in each of the coins examined. This information allowed the formulation of a possible minting method. Since twins in FCC metals are formed with thermal treatment, and mechanical twinning is rather improbable, it seems that the coins were initially hot-worked. Bent twins indicate that working continued during cooling. Especially for the Corcyra coin it was deduced that it was treated at higher temperature or its cooling rate was lower.

  12. Silver Sulfadiazine

    Science.gov (United States)

    Silver sulfadiazine, a sulfa drug, is used to prevent and treat infections of second- and third-degree burns. It ... Silver sulfadiazine comes in a cream. Silver sulfadiazine usually is applied once or twice a day. Follow the directions ...

  13. Analysis of medieval Serbian silver coins from XIV and XV century by means of wavelength-dispersive X-ray spectrometry

    Science.gov (United States)

    Gržetić, Ivan; Orlić, Jovana; Radić, Vesna; Radić, Milica; Ilijević, Konstantin

    2016-01-01

    X-ray fluorescence (XRF) spectrometry is known as excellent nondestructive technique for analysis of artifacts, in our case, medieval numismatic coins. Collections of 30 silver coins, owned by National Museum in Belgrade, were investigated during our research. Coins from the historical period from 1389 to 1458 belong to the reign of two Serbian rulers, Stefan Lazarević and Đurđe Branković. The aim of this study was to determine elemental composition of silver coins and to characterize alloys from which the coins were minted. The dominant elements detected in all coins were Ag, Cu, Zn and Pb. In some coins Fe, Si and S were detected as well. Results from quantitative analysis shows that the content of Ag in all investigated silver coins exceed 90%, except in two coins that were assumed to be forged. The concentration of Cu ranged from 3% to 5%, and the contents of Zn and Pb varied around 1%. Characterization of coins provided us information about raw materials and employed metallurgical processes.

  14. Gold and Silver as Monetary Metals

    OpenAIRE

    John Cooper

    2006-01-01

    Commodity money systems, based upon gold or silver, provided relative economic stability for centuries. On the other hand, our modern paper money system, based upon unbacked government liabilities, is particularly vulnerable to abuse. The various financial crises during the twentieth century bear witness to that. This paper seeks to explain the mechanics of the former Gold and Silver Standards and provides an overview of America’s experience with its bimetallic system.

  15. The instrumental climate history of southwestern Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Doesken, N.J.; McKee, T.B. [Colorado State Univ., Fort Collins, CO (United States)

    1995-09-01

    Instrumental observations of the climate of southwestern Colorado date back to about 1880. Climatic conditions since the late 19th century will be described with emphasis on temperatures, temperature ranges and observed precipitation. Typical seasonal patterns of temperature and precipitation will be shown, and variations and apparent trends over time will be discussed. Drought characteristics will be described based on a standardized precipitation index developed for Colorado. Finally, brief comments on the challenge of collecting accurate and consistent long-term data will be given.

  16. NOAA-CIRES 20th Century Reanalysis (V2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 20th Century Reanalysis version 2 (20CRV2)is an effort led by PSD and the CIRES at the University of Colorado to produce a reanalysis dataset spanning the...

  17. Colorado Library Program Assessment

    Science.gov (United States)

    Russell, Becky

    2012-01-01

    Colorado school librarians are in the midst of a crisis. According to a 2009-2010 survey of public schools in Colorado, just 23% of elementary schools have an endorsed librarian, while 37% of middle schools and 32% of high schools report having an endorsed librarian. This report also shows how these percentages have dropped in just a two-year…

  18. Census Snapshot: Colorado

    OpenAIRE

    Romero, Adam P; Rosky, Clifford J; Badgett, M. V. Lee; Gates, Gary J.

    2008-01-01

    Using data from the U.S. Census Bureau, this report provides demographic and economic information about same-sex couples and same-sex couples raising children in Colorado. We compare same-sex “unmarried partners,” which the Census Bureau defines as an unmarried couple who “shares living quarters and has a close personal relationship,” to different-sex married couples in Colorado. In many ways, the almost 16,000 same-sex couples living in Colorado are similar to married couples. According t...

  19. Microscopical Examination of Ancient Silver Coins

    International Nuclear Information System (INIS)

    The microstructure of three silver coins of the IIId century B.C. from the Illyrian king Monounios, the ancient Greek city of Dyrrachion and of Korkyra was studied with XRF and microscopy. From this investigation it turned out that these coins have different chemical composition and microstructure that imply different minting method

  20. Analysis of metals with luster: Roman brass and silver

    Science.gov (United States)

    Fajfar, H.; Rupnik, Z.; Šmit, Ž.

    2015-11-01

    Non-destructive PIXE analysis using in-air proton beam was used for the studies of earliest brass coins issued during the 1st century BC by Greek cities in Asia Minor, Romans and Celts, and for the studies of plated low grade silver coins of the 3rd century AD. The analysis determined the levels of zinc and important trace elements, notably selenium, which confirms spread of selenium-marked copper from the east. For plating, combined tinning and silvering was identified by the mapping technique for the mid 3rd century AD, which evolved into mere plating by 270 AD.

  1. BUFFALO PEAKS WILDERNESS STUDY AREA, COLORADO.

    Science.gov (United States)

    Hedlund, D.C.; Wood, R.H.

    1984-01-01

    Field investigations were conducted to evaluate the mineral-resource potential of the Buffalo Peaks Wilderness Study Area, Colorado. On the basis of this study there is a probable mineral-resource potential for silver vein and bedding replacement deposits along the Weston Pass fault zone, for hydrothermal vein-type uranium deposits in the vicinity of the Parkdale iron pit, and for gold vein deposits in the parts of the Granite and Four Mile districts that are within the wilderness study area. A probable barite resource potential occurs at Rough and Tumbling Creek and near Spring Creek on the east side of the study area. There is little promise for the occurrence of energy resources.

  2. Final Years of the Silver Standard in Mexico: Evidence of Purchasing Power Parity with The United States

    OpenAIRE

    Antonio N. Bojanic

    2011-01-01

    This paper focuses on the use of silver as a monetary standard in Mexico during approximately the last three decades of the nineteenth century and the first decade of the twentieth century. During this period, several events occurred in the market for silver that affected those countries attached to this metal. These events caused some of these countries to abandon silver for good and adopt other types of monetary arrangements. Mexico and a few others chose to stay with it. The reasons behind...

  3. Asbestos in Colorado Schools.

    Science.gov (United States)

    Baldwin, Cynthia A.

    This study determined, by means of a random sample, how many of Colorado's public schools have asbestos materials and estimated the potential risk of exposure presented by these materials. Forty-one schools were surveyed. Bulk samples of possible asbestos materials were collected and analyzed using the K-squared Asbestos Screening Test to…

  4. The Silver Halides

    Science.gov (United States)

    Sahyun, M. R. V.

    1977-01-01

    Illustrates the type of fractional bonding for solid silver halides. Treats the silver halides as electron excess compounds, and develops a model of a localized bonding unit that may be iterated in three dimensions to describe the bulk phase. (MLH)

  5. Colorado Geothermal Commercialization Program

    Energy Technology Data Exchange (ETDEWEB)

    Healy, F.C.

    1980-04-01

    Chaffee County, located in central Colorado, has immense potential for geothermal development. This report has been prepared to assist residents and developers in and outside the area to develop the hydrothermal resources of the county. Data has been collected and interpreted from numerous sources in order to introduce a general description of the area, estimate energy requirements, describe the resources and postulate a development plan. Electric power generation and direct heat application potential for the region are described.

  6. Einstein's Century

    Institute of Scientific and Technical Information of China (English)

    Jeremy Laurance; 贾庆文

    2005-01-01

    Albert Einstein began working at the patent office in Bern, Switzerland, a little more than a century ago. He had flunked the entrance exam for the Swiss Federal Insitute of Technology and took the job evaluating inventions because it paid a regular salary.

  7. MYCOSYNTHESIS OF SILVER NANOPARTICLES AND ANTIBACTERAL EFFECTS IN WOUND DRESSING

    Directory of Open Access Journals (Sweden)

    A. Avila Jerley* and A. Anita Margret

    2012-06-01

    Full Text Available Bionanotechnology has emerged up as integration between biotechnology and nanotechnology for developing biosynthetic and environmental friendly technology for synthesis of nano materials. Silver has been known to have effective bactericidal properties for centuries. Nowadays, silver based topical dressings have been widely used as a treatment for infection in burns, open wounds, and chronic ulcer. As the pathogenic organisms are getting evolved day by day due to mutation and gaining antibiotic resistance, an important industrial sector of nanosciene deals with the preparation and study of nanoparticles in antibacterial clothings, burn ointments and coating for medical device. The size of nanomaterials is much smaller than that of most biological molecules and structures, therefore nanomaterials can be useful in both in vivo and in vitro biomedical research application. The purpose of the study is to synthesis and characterizes the fungal silver nanoparticles using F.oxysporum. Further investigation of the shape and size of fungal nanoparticle was done by X-ray diffraction and Scanning electron microscopic studies. A silver nanoparticle at different concentration was assessed for its antibacterial effect, against various bacteria.Further Silver based topical dressing incorporated with fungal nanoparticle was prepared and integrated into cotton band aid gauze. This study revealed the enhancement of the synthesis of silver nanoparticles by the reduction of aqueous silver ions by simultaneous release of extracellular metabolites from the culture of F. oxysporum. It also focuses on the potential application of silver nanoparticles in the medical field as a topical dressing against various wound pathogens.

  8. NOAA-CIRES 20th Century Reanalysis (V2c)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 20th Century Reanalysis version 2c (20CRV2c)is an effort led by PSD and the CIRES at the University of Colorado to produce a reanalysis dataset spanning the...

  9. Color and dichroism of silver-stained glasses

    International Nuclear Information System (INIS)

    Yellow decorations in glasses have been produced since the beginning of the fourteenth century by incorporating metallic silver nanoparticles into the glass (from a few to some tens of nanometers). The optical response of the glass-particles composite is determined by the surface plasmon resonance absorption and scattering of the nanometric metallic particles. Generally, the same color is perceived in reflection and in transmission although dichroic effects are occasionally observed. As silver-stained glasses were designed to be observed in transmission, tuning the transmission color from yellow to red was of technological interest. The relationship between the color observed both in transmission and reflection and the composition and nanostructure of regular (yellow) and dichroic (yellow and red) silver stains from the Renaissance (late fifteenth and sixteenth century, respectively) is related to the presence of a layer (of about 10–20 μm thick) of metallic silver nanoparticles (from few to 100 nm in size). The correlation between the colors observed and the silver stain nanostructure is studied with particular emphasis on the origin of the dichroic behavior. The optical response is computed and compared to the experimental data. Differences in the synthesis parameters responsible for the colors and for the dichroic behavior of the silver stain glasses are proposed. This is essential for the replication of the glass pieces which are required as replacements in the restoration/conservation of the windows but is also of broader interest

  10. Color and dichroism of silver-stained glasses

    Energy Technology Data Exchange (ETDEWEB)

    Molina, Gloria [Universitat Politecnica de Catalunya, Center for Research in NanoEngineering (Spain); Murcia, Sonia [Universidad de Valencia, Instituto de Ciencia de los Materiales (Spain); Molera, Judit [Universitat de Vic, GRTD, Escola Politecnica Superior (Spain); Roldan, Clodoaldo [Universidad de Valencia, Instituto de Ciencia de los Materiales (Spain); Crespo, Daniel; Pradell, Trinitat, E-mail: Trinitat.Pradell@upc.edu [Universitat Politecnica de Catalunya, Center for Research in NanoEngineering (Spain)

    2013-09-15

    Yellow decorations in glasses have been produced since the beginning of the fourteenth century by incorporating metallic silver nanoparticles into the glass (from a few to some tens of nanometers). The optical response of the glass-particles composite is determined by the surface plasmon resonance absorption and scattering of the nanometric metallic particles. Generally, the same color is perceived in reflection and in transmission although dichroic effects are occasionally observed. As silver-stained glasses were designed to be observed in transmission, tuning the transmission color from yellow to red was of technological interest. The relationship between the color observed both in transmission and reflection and the composition and nanostructure of regular (yellow) and dichroic (yellow and red) silver stains from the Renaissance (late fifteenth and sixteenth century, respectively) is related to the presence of a layer (of about 10-20 {mu}m thick) of metallic silver nanoparticles (from few to 100 nm in size). The correlation between the colors observed and the silver stain nanostructure is studied with particular emphasis on the origin of the dichroic behavior. The optical response is computed and compared to the experimental data. Differences in the synthesis parameters responsible for the colors and for the dichroic behavior of the silver stain glasses are proposed. This is essential for the replication of the glass pieces which are required as replacements in the restoration/conservation of the windows but is also of broader interest.

  11. Colorado State Capitol Geothermal project

    Energy Technology Data Exchange (ETDEWEB)

    Shepherd, Lance [Colorado Department of Personnel and Adminstration, Denver, CO (United States)

    2016-04-29

    Colorado State Capitol Geothermal Project - Final report is redacted due to space constraints. This project was an innovative large-scale ground-source heat pump (GSHP) project at the Colorado State Capitol in Denver, Colorado. The project employed two large wells on the property. One for pulling water from the aquifer, and another for returning the water to the aquifer, after performing the heat exchange. The two wells can work in either direction. Heat extracted/added to the water via a heat exchanger is used to perform space conditioning in the building.

  12. Colorado wetlands initiative : 1997-2000 : Protecting Colorado's wetlands resource

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Colorado Wetlands Initiative is an endeavor to protect wetlands and wetland-dependent wildlife through the use of voluntary, incentive-based mechanisms. It is a...

  13. century drying

    Science.gov (United States)

    Cook, Benjamin I.; Smerdon, Jason E.; Seager, Richard; Coats, Sloan

    2014-11-01

    Global warming is expected to increase the frequency and intensity of droughts in the twenty-first century, but the relative contributions from changes in moisture supply (precipitation) versus evaporative demand (potential evapotranspiration; PET) have not been comprehensively assessed. Using output from a suite of general circulation model (GCM) simulations from phase 5 of the Coupled Model Intercomparison Project, projected twenty-first century drying and wetting trends are investigated using two offline indices of surface moisture balance: the Palmer Drought Severity Index (PDSI) and the Standardized Precipitation Evapotranspiration Index (SPEI). PDSI and SPEI projections using precipitation and Penman-Monteith based PET changes from the GCMs generally agree, showing robust cross-model drying in western North America, Central America, the Mediterranean, southern Africa, and the Amazon and robust wetting occurring in the Northern Hemisphere high latitudes and east Africa (PDSI only). The SPEI is more sensitive to PET changes than the PDSI, especially in arid regions such as the Sahara and Middle East. Regional drying and wetting patterns largely mirror the spatially heterogeneous response of precipitation in the models, although drying in the PDSI and SPEI calculations extends beyond the regions of reduced precipitation. This expansion of drying areas is attributed to globally widespread increases in PET, caused by increases in surface net radiation and the vapor pressure deficit. Increased PET not only intensifies drying in areas where precipitation is already reduced, it also drives areas into drought that would otherwise experience little drying or even wetting from precipitation trends alone. This PET amplification effect is largest in the Northern Hemisphere mid-latitudes, and is especially pronounced in western North America, Europe, and southeast China. Compared to PDSI projections using precipitation changes only, the projections incorporating both

  14. PIXE analysis of medieval silver coins

    International Nuclear Information System (INIS)

    We applied the proton-induced X-ray emission (PIXE) analytical technique to twenty-eight medieval silver coins, selected from the Tunisian treasury. The purpose is to study the fineness evolution from the beginning of the 7th to the 15th centuries AD. Each silver coin was cleaned with a diluted acid solution and then exposed to a 3 MeV proton beam from a 1.7 MV tandem accelerator. To allow the simultaneous detection of light and heavy elements, a funny aluminum filter was positioned in front of the Si(Li) detector entrance which is placed at 135o to the beam direction. The elements Cu, Pb, and Au were observed in the studied coins along with the major component silver. The concentration of Ag, presumably the main constituent of the coins, varies from 55% to 99%. This significant variation in the concentration of the major constituent reveals the economical difficulties encountered by each dynasty. It could be also attributed to differences in the composition of the silver mines used to strike the coins in different locations. That fineness evolution also reflects the poor quality of the control practices during this medieval period. In order to verify the ability of PIXE analytical method to distinguish between apparently similar coins, we applied hierarchical cluster analysis to our results to classify them into different subgroups of similar elemental composition.

  15. Copper and silver halates

    CERN Document Server

    Woolley, EM; Salomon, M

    2013-01-01

    Copper and Silver Halates is the third in a series of four volumes on inorganic metal halates. This volume presents critical evaluations and compilations for halate solubilities of the Group II metals. The solubility data included in this volume are those for the five compounds, copper chlorate and iodate, and silver chlorate, bromate and iodate.

  16. Evaluation of Silver Distribution within the Silver Doped Hydroxyapatite

    OpenAIRE

    Dubņika, A; Loča, D; Jakovļevs, D; Bērziņa-Cimdiņa, L.

    2013-01-01

    Various researches of silver doped hydroxyapatite (HAp/Ag) synthesis and evaluation can be found, but scarce information can be found on evaluation of silver distribution within powders and pallets depending on the material preparation method. Silver distribution is essential parameter responsible for silver release and material in vitro properties.

  17. The colour and golden shine of early silver Islamic lustre

    OpenAIRE

    Gutierrez Neira, Carolina; Pradell Cara, Trinitat; Molera Marimon, Judit; Smith, Andrew D; Climent Font, Aurelio; Tite, Michael S.

    2014-01-01

    A selection of lustres including 9th century AD polychrome and 10th century AD monochrome Abbasid lustres from Iraq, and 10th to 12th centuries AD Fatimid lustres from Egypt and Syria is studied in the present paper. The selection is based on previous studies that demonstrated that all of them contain metal silver nanoparticles and copper, which, when present, appears either as Cuþ or Cu2þ dissolved in the glaze. They show different colours, green, yellow, amber, and brown, and...

  18. Colorados asutati rohelise ehituse toetusprogramm

    Index Scriptorium Estoniae

    2002-01-01

    USA Colorado osariigi rohelised arhitektid ja projekteerijad asutasid koos ehitusfirmadega programmi "Ehita rohelist Coloradot", mille raames pakutakse rohelise maja või korteri ehitamise väljaõpet

  19. The 21st Century as Whose Century?

    Directory of Open Access Journals (Sweden)

    David Scott

    2015-08-01

    Full Text Available Macro-analysis and East-West encounter are shown through consideration of objective yet subjective constructed concepts for the international system and international economy in the 21st century. Three paradigms are considered, namely the 21st century as the ‘Pacific Century’, as ‘China’s Century’ and as the ‘Asian Century’. Overlaps are shown between these three paradigms, as also developments in time, and gradually shift in geographical location. The ‘Pacific Century’, and its associated Rimspeak, was the paradigm emerging in the late 1970s, knitting together America’s West Coast and the Japanese economy. By the late 1980s this was already shifting to talk of the 21st century likely to be an ‘Asian Century’ model, mark-1, based on the Pacific Asia dynamism shown by the ‘Asian Tigers’ and Japan. However, the Asian financial crash of 1997-8, and the economic downturn in Japan, meant that such an ‘Asian Century’ seemed premature as the 21st century arrived. Instead, it was China’s economic growth that seemed most evident, and with it the concept of the 21st century as ‘China’s Century’. However, in turn that has already been modified during the first decade of the century by India’s arrival as a rapidly growing economy. Consequently the 21st century as ‘China’s Century’ and as ‘India’s Century’ has been combined into talk of an ‘Asian Century’, mark-2.

  20. Debris Flow Occurrence and Sediment Persistence, Upper Colorado River Valley, CO

    Science.gov (United States)

    Grimsley, K. J.; Rathburn, S. L.; Friedman, J. M.; Mangano, J. F.

    2016-07-01

    Debris flow magnitudes and frequencies are compared across the Upper Colorado River valley to assess influences on debris flow occurrence and to evaluate valley geometry effects on sediment persistence. Dendrochronology, field mapping, and aerial photographic analysis are used to evaluate whether a 19th century earthen, water-conveyance ditch has altered the regime of debris flow occurrence in the Colorado River headwaters. Identifying any shifts in disturbance processes or changes in magnitudes and frequencies of occurrence is fundamental to establishing the historical range of variability (HRV) at the site. We found no substantial difference in frequency of debris flows cataloged at eleven sites of deposition between the east (8) and west (11) sides of the Colorado River valley over the last century, but four of the five largest debris flows originated on the west side of the valley in association with the earthen ditch, while the fifth is on a steep hillslope of hydrothermally altered rock on the east side. These results suggest that the ditch has altered the regime of debris flow activity in the Colorado River headwaters as compared to HRV by increasing the frequency of debris flows large enough to reach the Colorado River valley. Valley confinement is a dominant control on response to debris flows, influencing volumes of aggradation and persistence of debris flow deposits. Large, frequent debris flows, exceeding HRV, create persistent effects due to valley geometry and geomorphic setting conducive to sediment storage that are easily delineated by valley confinement ratios which are useful to land managers.

  1. Survey for bats in Jackson County, Colorado

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report covers a targeted bat survey of Jackson County in north-central Colorado to better understand the abundance and distribution of bats in Colorado. The...

  2. CRevolution 2—Origin and evolution of the Colorado River system, workshop abstracts

    Science.gov (United States)

    : Beard, L. Sue, (Edited By); Karlstrom, Karl E.; Young, Richard A.; Billingsley, George H.

    2011-01-01

    A 2010 Colorado River symposium, held in Flagstaff, Arizona, involved 70 participants who engaged in intense debate about the origin and evolution of the Colorado River system. This symposium, built upon two previous decadal scientific meetings, focused on forging scientific consensus, where possible, while articulating continued controversies regarding the Cenozoic evolution of the Colorado River System and the landscapes of the Colorado Plateau-Rocky Mountain region that it drains. New developments involved hypotheses that Neogene mantle flow is driving plateau tilting and differential uplift and new and controversial hypotheses for the pre-6 Ma presence and evolution of ancestral rivers that may be important in the history and birth of the present Colorado River. There is a consensus that plateau tilt and uplift models must be tested with multidisciplinary studies involving differential incision studies and additional geochronology and thermochronology to determine the relative importance of tectonic and geomorphic forces that shape the spectacular landscapes of the Colorado Plateau, Arizona and region. In addition to the scientific goals, the meeting participants emphasized the iconic status of Grand Canyon for geosciences and the importance of good communication between the research community, the geoscience education/interpretation community, the public, and the media. Building on a century-long tradition, this region still provides a globally important natural laboratory for studies of the interactions of erosion and tectonism in shaping the landscape of elevated plateaus.

  3. Silver ion release from antimicrobial polyamide/silver composites

    OpenAIRE

    Kumar, Radhesh; Münstedt, Helmut

    2005-01-01

    Silver ion (Ag+) the versatile antimicrobial species was released in a steady and prolonged manner from a silver-filled polyamide composite system. Metallic silver powder having varying specific surface area (SSA) has been used as a resource of biocide in polyamide. Strong evidences are found showing the release of the antimicrobial species from the resulting composite upon soaking it in water due to the interaction of the diffused water molecules with the dispersed silver powder wit...

  4. Silver Nanoparticles as Potential Antibacterial Agents

    Directory of Open Access Journals (Sweden)

    Gianluigi Franci

    2015-05-01

    Full Text Available Multi-drug resistance is a growing problem in the treatment of infectious diseases and the widespread use of broad-spectrum antibiotics has produced antibiotic resistance for many human bacterial pathogens. Advances in nanotechnology have opened new horizons in nanomedicine, allowing the synthesis of nanoparticles that can be assembled into complex architectures. Novel studies and technologies are devoted to understanding the mechanisms of disease for the design of new drugs, but unfortunately infectious diseases continue to be a major health burden worldwide. Since ancient times, silver was known for its anti-bacterial effects and for centuries it has been used for prevention and control of disparate infections. Currently nanotechnology and nanomaterials are fully integrated in common applications and objects that we use every day. In addition, the silver nanoparticles are attracting much interest because of their potent antibacterial activity. Many studies have also shown an important activity of silver nanoparticles against bacterial biofilms. This review aims to summarize the emerging efforts to address current challenges and solutions in the treatment of infectious diseases, particularly the use of nanosilver antimicrobials.

  5. Silver nanoparticles as potential antibacterial agents.

    Science.gov (United States)

    Franci, Gianluigi; Falanga, Annarita; Galdiero, Stefania; Palomba, Luciana; Rai, Mahendra; Morelli, Giancarlo; Galdiero, Massimiliano

    2015-01-01

    Multi-drug resistance is a growing problem in the treatment of infectious diseases and the widespread use of broad-spectrum antibiotics has produced antibiotic resistance for many human bacterial pathogens. Advances in nanotechnology have opened new horizons in nanomedicine, allowing the synthesis of nanoparticles that can be assembled into complex architectures. Novel studies and technologies are devoted to understanding the mechanisms of disease for the design of new drugs, but unfortunately infectious diseases continue to be a major health burden worldwide. Since ancient times, silver was known for its anti-bacterial effects and for centuries it has been used for prevention and control of disparate infections. Currently nanotechnology and nanomaterials are fully integrated in common applications and objects that we use every day. In addition, the silver nanoparticles are attracting much interest because of their potent antibacterial activity. Many studies have also shown an important activity of silver nanoparticles against bacterial biofilms. This review aims to summarize the emerging efforts to address current challenges and solutions in the treatment of infectious diseases, particularly the use of nanosilver antimicrobials. PMID:25993417

  6. Leaching of Silver from Silver-Impregnated Food Storage Containers

    Science.gov (United States)

    Hauri, James F.; Niece, Brian K.

    2011-01-01

    The use of silver in commercial products has proliferated in recent years owing to its antibacterial properties. Food containers impregnated with micro-sized silver promise long food life, but there is some concern because silver can leach out of the plastic and into the stored food. This laboratory experiment gives students the opportunity to…

  7. Roman lead silver smelting at Rio Tinto: the case study of Corta Lago

    OpenAIRE

    Anguilano, L

    2012-01-01

    The Rio Tinto area is famous for the presence there of a rich concentration of several metals, in particular copper, silver and manganese, which were exploited from the Bronze Age up to few decades ago. The modern mining industry has been responsible for both bringing to light and destroying signs of past exploitation of the mines and metal production there. The Corta Lago site owes its discovery to the open cast exploitation that reduced the whole mount of Cerro Colorado to an artificial ...

  8. Dendroclimatic reconstructions for the southern Colorado plateau

    Energy Technology Data Exchange (ETDEWEB)

    Dean, J.S.; Funkhouser, G.S. [Univ. of Arizona, Tucson, AZ (United States)

    1995-09-01

    A geographical network of climate sensitive tree-ring chronologies consisting of 25 archaeological sequences and two bristlecone pine series provides the basis for high resolution reconstructions of low and high frequency climatic variability on the southern Colorado Plateau over the last 1,500 years. Qualitative and quantitative dendroclimatic analyses of these data produce annual retrodictions of yearly and seasonal precipitation and summer Palmer Drought Severity Indices for each station and reconstructions of regional scale patterns in climatic variability. These reconstructions provide detailed information on climatic fluctuations that affected biotic and human populations as well as long-term baseline data for evaluating present-day climate and estimating future climatic trends. When integrated with other measures of past environmental variability, these reconstructions specify periods of favorable and unfavorable environmental conditions that would have affected past human populations of the region. The severest degradation, which occurred between A.D. 1250 and 1450, probably was causally related to numerous cultural changes that occurred at the end of the l3th century including the Anasazi abandonment of the Four Comers area. Projecting environmental patterns that characterized the last two millennia into the future indicates potential hazards to long term uranium mill waste disposal and containment and the potential and limitations of environmental restoration.

  9. Silver accumulation in macrofungi

    Czech Academy of Sciences Publication Activity Database

    Borovička, Jan; Kotrba, P.; Gryndler, Milan

    Elsevier. Roč. 72, č. 12 (2008), A99-A99. ISSN 0016-7037. [8th Annual V M Goldschmidt Conference. xx.07.2008, Vancouver] R&D Projects: GA AV ČR(CZ) IAA600480801 Institutional research plan: CEZ:AV0Z10480505; CEZ:AV0Z50200510 Keywords : silver * macrofungi Subject RIV: CH - Nuclear ; Quantum Chemistry

  10. Potted Silver Carp

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Ingredients: 4 silver carp of about 200 grams each, mushrooms, winter bamboo shoots, minced ginger root and scallions, cooking wine, broth, salt and MSG (optional). Method: 1. After cleaning the carp place them in a pot; add in all other ingredients and some broth, Seal the opening of the pot with kraft paper

  11. Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

    Energy Technology Data Exchange (ETDEWEB)

    Kvitek, L; Panacek, A; Prucek, R; Soukupova, J; Vanickova, M; Zboril, R [Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17. Listopadu 12, 77146 Olomouc (Czech Republic); Kolar, M, E-mail: ales.panacek@upol.cz [Department of Microbiology, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 77520 Olomouc (Czech Republic)

    2011-07-06

    The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.

  12. Climate change and changes in sediment transport capacity in the Colorado Plateau, USA

    Science.gov (United States)

    Milhous, R.T.

    2005-01-01

    Information is presented on changes in the sediment transport capacity of streams of the Colorado Plateau region of the United States. The changes in transport capacity may be due to changes in climate. Changes in the ability of three rivers in the Colorado Plateau to transport sediment were investigated (Paria River at Lees Ferry, Arizona; Sevier River at Hatch, Utah; and Little Colorado at Woodruff, Arizona) using an index to sediment transport potential (or capacity) of the rivers. The index is called a Sediment Transport Capacity Index (STCI). The parameters in the index are calibrated to measured sediment concentrations. Other investigators have postulated that there have been three climate regimes in the Colorado Plateau during the 20th century: 1905-1941, 1942-1977 and 1978-1998. Time series analyses of the STCI showed reasonably clearly that there was a change in the climate about 1941 and a high probability of a change about 1923-1929. The STCI time series for the Sevier River had the expected pattern because the STCI increased in the years following 1997 nearly to the pre-1942 values from lower 1942-1977 values. The Little Colorado River showed a similar pattern, but not nearly to the magnitude suggested by the change in precipitation. The STCI for the Paria River essentially did not change. Changes in sediment transport also are investigated in the lower San Juan River where alterations in the sediment balance of the river may be due to variations in the character of summer precipitation.

  13. Mineral resources of the Holy Cross Wilderness Area, Eagle, Pitkin, and Lake Counties, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, A.R.; Lee, G.K.; Campbell, D.L.; Lundby, W.; Brown, S.D.

    1989-01-01

    The Holy Cross Wilderness Area is in the northern Sawatch Range of central Colorado. This area is underlain principally by Proterozoic metamorphic and igneous rocks, which are unconformably overlain by Paleozoic sedimentary rocks along the flanks of the range. Numerous Late Cretaceous and Tertiary plutons were emplaced into the older rocks, and all rocks are cut by numerous faults. Identified resources in this wilderness area include high-purity limestone and gold-silver ore. Parts of this wilderness area have a high or a moderate resource potential for deposits of base and precious metals and molybdenum, for sand and gravel, and for high-purity limestone.

  14. Mining the Colorado Plateau: the Story of Calamity Mesa 1910-19

    OpenAIRE

    Godfrey, Lisa Pitcher

    1991-01-01

    This thesis was written to outline the history of five stone houses, which have survived almost a century of mining activity. The houses are located on a barren mesa, called Calamity, in southwestern Colorado. This work was funded by the Bureau of Land Management, Department of the Interior, in order to explore the possibility of designating this site as a National Historic Site. Men and women lived and worked on this and the surrounding mesas for most of the twentieth century. The lives o...

  15. 78 FR 29321 - Colorado Recreation Resource Advisory Committee Meeting

    Science.gov (United States)

    2013-05-20

    ... Forest Service Colorado Recreation Resource Advisory Committee Meeting AGENCY: Rocky Mountain Region, Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Colorado Recreation Resource Advisory... National Forest. Proposals, updates, and other information can be found on the Colorado Recreation...

  16. 2011 Kids Count in Colorado! The Impact of the Great Recession on Colorado's Children

    Science.gov (United States)

    Colorado Children's Campaign, 2011

    2011-01-01

    "Kids Count in Colorado!" is an annual publication of the Colorado Children's Campaign, which provides the best available state- and county-level data to measure and track the education, health and general well-being of the state's children. "Kids Count in Colorado!" informs policy debates and community discussions, serving as a valuable resource…

  17. 78 FR 9629 - Irish Potatoes Grown in Colorado; Reestablishment of Membership on the Colorado Potato...

    Science.gov (United States)

    2013-02-11

    ...; ] DEPARTMENT OF AGRICULTURE Agricultural Marketing Service 7 CFR Part 948 Irish Potatoes Grown in Colorado; Reestablishment of Membership on the Colorado Potato Administrative Committee, Area No. 2 AGENCY: Agricultural... membership on the Colorado Potato Administrative Committee, Area No. 2 (Committee). The Committee...

  18. 77 FR 32980 - Notice of Correction to Filing of Plats, Colorado

    Science.gov (United States)

    2012-06-04

    ... Management (BLM) published a Notice of Filing of Plats by the Colorado State Office, Lakewood, Colorado . The... Surveyor for Colorado, BLM, Colorado State Office, 2850 Youngfield Street, Lakewood, Colorado...

  19. Silver against Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Kirketerp-Møller, K.; Kristiansen, S.;

    2007-01-01

    bacteria in both the planktonic and biofilm modes of growth. The action of silver on mature in vitro biofilms of Pseudomonas aeruginosa, a primary pathogen of chronic infected wounds, was investigated. The results show that silver is very effective against mature biofilms of P. aeruginosa, but that the...... silver concentration is important. A concentration of 5-10 ig/mL silver sulfadiazine eradicated the biofilm whereas a lower concentration (1 ig/mL) had no effect. The bactericidal concentration of silver required to eradicate the bacterial biofilm was 10-100 times higher than that used to eradicate...... planktonic bacteria. These observations strongly indicate that the concentration of silver in currently available wound dressings is much too low for treatment of chronic biofilm wounds. It is suggested that clinicians and manufacturers of the said wound dressings consider whether they are treating wounds...

  20. Extraction of Silver by Glucose.

    Science.gov (United States)

    Baksi, Ananya; Gandi, Mounika; Chaudhari, Swathi; Bag, Soumabha; Gupta, Soujit Sen; Pradeep, Thalappil

    2016-06-27

    Unprecedented silver ion leaching, in the range of 0.7 ppm was seen when metallic silver was heated in water at 70 °C in presence of simple carbohydrates, such as glucose, making it a green method of silver extraction. Extraction was facilitated by the presence of anions, such as carbonate and phosphate. Studies confirm a two-step mechanism of silver release, first forming silver ions at the metal surface and later complexation of ionic silver with glucose; such complexes have been detected by mass spectrometry. Extraction leads to microscopic roughening of the surface making it Raman active with an enhancement factor of 5×10(8) . PMID:27119514

  1. Investigation of Silver Doped Hydroxyapatite

    OpenAIRE

    Dubņika, A; Loča, D; Mālniece, L

    2012-01-01

    Biomaterials based on calcium phosphate ceramics are used as implants in human/animal body due to their excellent biocompatibility. Silver containing materials have a very broad spectrum of antibacterial activity; therefore silver doped hydroxyapatite can be used in medicine as antibacterial implant material. The aim of this work was to synthesize monophasic and biphasic silver doped hydroxyapatite and evaluate the differences in their physical and antibacterial properties.

  2. Silver Ink For Jet Printing

    Science.gov (United States)

    Vest, R. W.; Singaram, Saraswathi

    1989-01-01

    Metallo-organic ink containing silver (with some bismuth as adhesion agent) applied to printed-circuit boards and pyrolized in air to form electrically conductive patterns. Ink contains no particles of silver, does not have to be mixed during use to maintain homogeneity, and applied to boards by ink-jet printing heads. Consists of silver neodecanoate and bismuth 2-ethylhexanoate dissolved in xylene and/or toluene.

  3. Polyaniline - silver composites

    Czech Academy of Sciences Publication Activity Database

    Bober, Patrycja; Stejskal, Jaroslav; Trchová, Miroslava; Prokeš, J.

    Atlanta : Center for Organic Photonics and Electronics - Georgia Institute of Technology, 2012. s. 345. [International Conference on Science and Technology of Synthetic Metals 2012 - ICSM 2012. 08.07.2012-13.07.2012, Atlanta] R&D Projects: GA ČR GA202/09/1626 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : polyaniline * silver * composites Subject RIV: BK - Fluid Dynamics

  4. Daniel Silver: Openings

    OpenAIRE

    Williams, Gilda

    2008-01-01

    MUCH OF LONDON-BASED SCULPTOR Daniel Silver’s work occupies an in-between state—between complete and incomplete, between handmade and mass-produced, between artistic object and castoff. For an exhibition at Ibid Projects in London this past winter, for example, Silver acquired several discarded marble copies of Roman and Greek statuary, recently carved in Carrara, Italy, that had been tossed aside by local artisans because the sculptures were cracked, chipped, or rendered crooked during their...

  5. Silver Studio textile project.

    OpenAIRE

    Hendon, Zoë

    2007-01-01

    This talk outlined the phased process by which the Museum of Domestic Design & Architecture improved the storage and documentation of its Silver Studio textile collection. Several small allocations of external funding were used to lever in a larger AHRB award. This talk outlined both the problem and the solution to museum professionals as part of a training day aimed at encouraging museums to achieve Accreditation.

  6. Characterization of Electrochemically Generated Silver

    Science.gov (United States)

    Adam, Niklas; Martinez, James; Carrier, Chris

    2014-01-01

    Silver biocide offers a potential advantage over iodine, the current state of the art in US spacecraft disinfection technology, in that silver can be safely consumed by the crew. Low concentrations of silver (Russian segment of the International Space Station has utilized an electrochemically generated silver solution, which is colloidal in nature. To be able to reliably provide a silver biocide to drinking water by electrochemical means would reduce mass required for removing another biocide such as iodine from the water. This would also aid in crew time required to replace iodine removal cartridges. Future long term missions would benefit from electrochemically produced silver as the biocide could be produced on demand and requires only a small concentration to be effective. Since it can also be consumed safely, there is less mass in removal hardware and little consumables required for production. The goal of this project initially is to understand the nature of the electrochemically produced silver, the particle sizes produced by the electrochemical cell and the effect that voltage adjustment has on the particle size. In literature, it has been documented that dissolved oxygen and pH have an effect on the ionization of the electrochemical silver so those parameters would be measured and possibly adjusted to understand their effect on the silver.

  7. Studies on ancient silver metallurgy using SR XRF and micro-PIXE

    Science.gov (United States)

    Vasilescu, Angela; Constantinescu, Bogdan; Stan, Daniela; Radtke, Martin; Reinholz, Uwe; Buzanich, Guenter; Ceccato, Daniele

    2015-12-01

    This work presents a complex evaluation of a series of Geto-Thracian silver adornments found on Romanian territory, part of the 4th century BC Agighiol (Northern Dobruja) hoard and of an ingot from the 1st century BC Geto-Dacian Surcea (Transylvania) hoard, using Synchrotron Radiation X-Ray Fluorescence and micro- Proton Induced X-ray Emission analysis and mapping in order to investigate aspects related to the elemental composition of the metal and the metallurgy implied in their manufacture. One of the samples can be linked to Laurion as the source of metal, and several items contain silver probably originated in Macedonia. The set of silver items was found to be heteregenous as composition and microstructure, and corrosion-related elements could be also identified in the X-Ray maps.

  8. Neutron activation analysis of ancient silver coins

    International Nuclear Information System (INIS)

    The amounts of gold and copper present as impurities in 500 Creek silver coins of the fifth century B.C. have been determined with a gamma-ray spectrometer, following neutron activation. The coinage from eight cities and kingdoms was studied; the average gold-content for different groups of coins varies between 0.02% and 0.3%, and the copper content between 0.1% and 10%. Evidence about trading connexions and of deliberate debasements of the coinage has been obtained, and several unsuspected plated coins were detected. The gold content was determined by measuring the intensity of the 0.411 MeV gamma-ray from Au198 (2.69 d); for the copper content the 0.511 MeV positron annihilation radiation from Cu64 (12.8 h) was used, and for silver the 0.884 MeV gamma-ray from Ag110m (253 d). Decay measurements were used as a check of identity. The technique of using total gamma-activity decay curves by themselves is insufficiently sensitive. For accurate work, the importance of approximate facsimile standards is stressed. (author)

  9. 2013 Kids Count in Colorado! Community Matters

    Science.gov (United States)

    Colorado Children's Campaign, 2013

    2013-01-01

    "Kids Count in Colorado!" is an annual publication of the Children's Campaign, providing state and county level data on child well-being factors including child health, education, and economic status. Since its first release 20 years ago, "Kids Count in Colorado!" has become the most trusted source for data and information on…

  10. [Ag25(SR)18]¯: The ‘Golden’ Silver Nanoparticle

    KAUST Repository

    Joshi, Chakra P

    2015-08-31

    Silver nanoparticles with an atomically precise molecular formula [Ag25(SR)18]¯ (‒SR: thiolate) are synthesized and their single-crystal structure is determined. This synthesized nanocluster is the only silver nanoparticle that has a virtually identical analogue in gold, i.e., [Au25(SR)18]¯, in terms of number of metal atoms, ligand count, super-atom electronic configuration, and atomic arrangement. Furthermore, both [Ag25(SR)18]¯ and its gold analogue share a number of features in their optical absorption spectra. This unprecedented molecular synthesis in silver to mimic gold offers the first model nanoparticle platform to investigate the centuries-old problem of understanding the fundamental differences between silver and gold in terms of nobility, catalytic activity, and optical property.

  11. Colorado's prospectus on uranium milling

    International Nuclear Information System (INIS)

    The first part of this paper will discuss Colorado's control of uranium mill tailings under Titles I and II of the Uranium Mill Tailings Radiation Control Act of 1978. Colorado has a legacy of nine inactive mill sites requiring reclamation under Title I, and two presently active plus a number of new mill proposals which must be regulated in accordance with Title II. Past failures in siting and control on the part of federal jurisdictions have left the state with a heavy legacy requiring extensive effort to address impacts to the state's environment and population. The second part of this paper will discuss the remedial action programme authorized under Public Law 92-314 for Mesa Country, where lack of federal control led to the dispersal of several hundred thousand tons of uranium mill tailings on thousands of properties, including hundreds of homes, schools and other structures. Successful completion of the State efforts under both programmes will depend on a high level of funding and on the maintenance of adequate regulatory standards. (author)

  12. Energy Smart Colorado, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Gitchell, John M. [Program Administrator; Palmer, Adam L. [Program Manager

    2014-03-31

    Energy Smart Colorado is an energy efficiency program established in 2011 in the central mountain region of Colorado. The program was funded through a grant of $4.9 million, awarded in August 2010 by the U.S. Department of Energy’s Better Buildings Program. As primary grant recipient, Eagle County coordinated program activities, managed the budget, and reported results. Eagle County staff worked closely with local community education and outreach partner Eagle Valley Alliance for Sustainability (now Walking Mountains Science Center) to engage residents in the program. Sub-recipients Pitkin County and Gunnison County assigned local implementation of the program in their regions to their respective community efficiency organizations, Community Office for Resource Efficiency (CORE) in Pitkin County, and Office for Resource Efficiency (ORE) in Gunnison County. Utility partners contributed $166,600 to support Home Energy Assessments for their customers. Program staff opened Energy Resource Centers, engaged a network of qualified contractors, developed a work-flow, an enrollment website, a loan program, and a data management system to track results.

  13. Corrosion protection for silver reflectors

    Energy Technology Data Exchange (ETDEWEB)

    Arendt, Paul N. (Los Alamos, NM); Scott, Marion L. (Los Alamos, NM)

    1991-12-31

    A method of protecting silver reflectors from damage caused by contact with gaseous substances which are often present in the atmosphere and a silver reflector which is so protected. The inventive method comprises at least partially coating a reflector with a metal oxide such as aluminum oxide to a thickness of 15 .ANG. or less.

  14. 7 CFR 948.51 - Colorado Potato Committee.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Colorado Potato Committee. 948.51 Section 948.51... Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Committees § 948.51 Colorado Potato Committee. The Colorado Potato...

  15. 7 CFR 948.151 - Colorado Potato Committee membership.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Colorado Potato Committee membership. 948.151 Section... POTATOES GROWN IN COLORADO Rules and Regulations Modification of Inspection Requirements § 948.151 Colorado Potato Committee membership. The Colorado Potato Committee shall be comprised of six members...

  16. Vacancies in silver

    International Nuclear Information System (INIS)

    Resistivity and positron lifetime measurements were performed to follow the annealing of the vacancy defects in quenched or irradiated high purity silver. For quench temperatures in the range 4000C to 5000C, the quenched-in resistivity is restored in one single stage centered at 400C. An activation energy of 0.64 +- 0.06 eV is inferred for the migration of the single vacancies. This result together with the information derived from the evolution of positron lifetime spectra leads to the conclusion that stage III is to be assigned to monovacancy migration. Further results obtained in α-AgZn solid solutions support this view. (author)

  17. Nineteenth-Century English

    DEFF Research Database (Denmark)

    Fabricius, Anne

    2009-01-01

    The article reviews the book "Nineteenth-Century English: Stability and Change," by Merja Kytö, Mats Rydèn and Erik Smitterberg......The article reviews the book "Nineteenth-Century English: Stability and Change," by Merja Kytö, Mats Rydèn and Erik Smitterberg...

  18. Oral toxicity of silver ions, silver nanoparticles and colloidal silver – a review

    DEFF Research Database (Denmark)

    Hadrup, Niels; Lam, Henrik Rye

    2014-01-01

    Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin...

  19. Thermal stability of PLD grown silver nanoparticles

    Science.gov (United States)

    Shokeen, Poonam; Jain, Amit; Kapoor, Avinashi

    2016-05-01

    Present work discusses the stability of silver nanoparticles at different annealing temperatures. Air muffle furnace annealing is performed to study the thermal stability of pulsed laser deposited silver nanoparticles. Silver reacts with atmospheric oxygen to form silver oxide at annealing temperatures below 473K and thermal decomposition of silver oxide takes place at temperatures above 473K. Oxide formation results in core shrinkage of silver, which in turn affects the surface plasmon resonance of silver nanoparticles. With increase in annealing temperature, the surface plasmon effect of nanoparticles starts to fade. SEM, XRD and UV-vis spectroscopy have been performed to analysis various structural and optical properties.

  20. A Silver DNAzyme.

    Science.gov (United States)

    Saran, Runjhun; Liu, Juewen

    2016-04-01

    Silver is a very common heavy metal, and its detection is of significant analytical importance. DNAzymes are DNA-based catalysts; they typically recruit divalent and trivalent metal ions for catalysis. Herein, we report a silver-specific RNA-cleaving DNAzyme named Ag10c obtained after six rounds of in vitro selection. Ag10c displays a catalytic rate of 0.41 min(-1) with 10 μM Ag(+) at pH 7.5 with 200 mM NaNO3, while its activity is completely inhibited with the same concentration of NaCl. Ag10c is highly specific for Ag(+) among all the tested metals. A catalytic beacon biosensor is designed by labeling a fluorophore and a quencher on the DNAzyme. Fluorescence enhancement is observed in the presence of Ag(+) with a detection limit of 24.9 nM Ag(+). The sensor shows a similar analytical performance in Lake Huron water. This is the first monovalent transition metal dependent RNA-cleaving DNAzyme. Apart from its biosensor application, this study strengthens the idea of exploring beyond the traditional understanding of multivalent ion dependent DNAzyme catalysis. PMID:26977895

  1. Biosynthesis of Silver Nanoparticles Using Marine Sponge

    OpenAIRE

    Mahta Rezazaeh Hamed; Mohammad Hadi Givianrad; Ali Mashinchian Moradi

    2015-01-01

    Biosynthesis of silver nanoparticles using marine sponge extract Haliclona was carried out. Marine sponges' extracts are responsible for the reduction of silver nitrate solution. Silver nanoparticles synthesized using fresh and dry marine sponge. Experimental factors including, time duration, pH, temperature were optimized. Silver nanoparticles were characterized by UV-Visible spectrophotometry. The sizes of synthesis silver nanoparticles were 27-46 nm and confirmed by scanning electron micro...

  2. MOD silver metallization for photovoltaics

    Science.gov (United States)

    Vest, G. M.; Vest, R. W.

    1985-01-01

    The feasibility of utilizing metallo-organic decomposition (MOD) silver inks were investigated for front contact metallization of solar cells. Generic synthesis procedures were developed for all metallo-organic compounds investigated. Silver neodecanoate was found to be the most suitable silver metallo-organic compound for use in thick film inks, but the quality of the inks was found to be highly dependent on its purity. Although neither the process nor inks were completely optimized for solar cell front contact metallization, they show great promise for this application.

  3. Colorado Plateau Rapid Ecoregion Assessment Data Catalog

    Data.gov (United States)

    Bureau of Land Management, Department of the Interior — Datasets used in the analysis of the Colorado Plateau (COP) Rapid Ecoregion Assessment (REA).They can be downloaded via a layer package (lpk, similar to a zip file...

  4. Notes and comments on Colorado Refuges

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report is a summary of actual management actions, and plant community responses on Colorado refuges during 1992. It is part of the moist-soil expert system...

  5. Silver matrix composites reinforced with galvanically silvered particles

    Directory of Open Access Journals (Sweden)

    J. Śleziona

    2007-08-01

    Full Text Available Purpose: The paper presents the possibility of the application of metalic layers drifted with the use of the galvanic methods on the ceramic particles surface. The application of the layers was aimed at obtaining the rewetting of the reinforcing particles with the liquid silver in the course of the producing of silver matrix composites with the use of mechanical stirring method. To enable introducing of the iron powder and glass carbon powder to liquid silver the solution of covering the powder layer with the silver or copper coats was proposed.Design/methodology/approach: For silver coating the method of non-current deposition from the solution was used.Findings: Conducted investigations allowed such a selection of non-current coating parameters that durable and qualitatively satisfactory coats on the iron particles surface could be obtained.Research limitations/implications: In the course of the researches it was stated that the temperature of the bath, the time of the spread and the intensity of the stirring were the most important parameters of the deposition method itself that guaranteed the obtaining of the coat. The conducted investigations allow to state that the most favourably from the quality of the obtained composite point of view were the applications of the silver coat on the surface of the iron particles and copper coat for glass carbon covering.Originality/value: Selection of the deposited galvanic coats allows to obtain the good quality of the connection on the reinforcing particle sliver matrix interface.

  6. Antimicrobial effects of silver zeolite, silver zirconium phosphate silicate and silver zirconium phosphate against oral microorganisms

    Institute of Scientific and Technical Information of China (English)

    Sirikamon Saengmee-anupharb; Toemsak Srikhirin; Boonyanit Thaweboon; Sroisiri Thaweboon; Taweechai Amornsakchai; Surachai Dechkunakorn; Theeralaksna Suddhasthira

    2013-01-01

    Objective: To evaluate the antimicrobial activities of silver inorganic materials, including silver zeolite (AgZ), silver zirconium phosphate silicate (AgZrPSi) and silver zirconium phosphate (AgZrP), against oral microorganisms. In line with this objective, the morphology and structure of each type of silver based powders were also investigated. Methods: The antimicrobial activities of AgZ, AgZrPSi and AgZrP were tested against Streptococcus mutans, Lactobacillus casei, Candidaalbicans and Staphylococcus aureus using disk diffusion assay as a screening test. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined using the modified membrane method. Scanning electron microscope and X-ray diffraction were used to investigate the morphology and structure of these silver materials. Results: All forms of silver inorganic materials could inhibit the growth of all test microorganisms. The MIC of AgZ, AgZrPSi and AgZrP was 10.0 g/L whereas MLC ranged between 10.0-60.0 g/L. In terms of morphology and structure, AgZrPSi and AgZrP had smaller sized particles (1.5-3.0 µm) and more uniformly shaped than AgZ. Conclusions: Silver inorganic materials in the form of AgZ, AgZrPSi and AgZrP had antimicrobial effects against all test oral microorganisms and those activities may be influenced by the crystal structure of carriers. These results suggest that these silver materials may be useful metals applied to oral hygiene products to provide antimicrobial activity against oral infection.

  7. DRDO Silver Jubilee Celebrations

    Directory of Open Access Journals (Sweden)

    Director DESIDOC

    2002-01-01

    Full Text Available DESIDOC actively participated in the DRDO Silver Jubilee Celebrations and made valuable contributions through the publicity programmes of the celebrations. as the Centre was entrusted with the responsibility . A colour-documentary film on the role of DRDO for Defence was arranged with Delhi Doordarshan. The TV documentary on DRDO was telecast on 14 Jan 1984 in the National Programme. The film was highly appreciated by the Scientific Adviser to Raksha Mantri, the Chief Controllers of R&D and several Directors of DR DO Labs/ Estts. A number of articles were prepared by DESIDOC on the achievements of DRDO in various fields, for publication in Sainik Samachar, R&D Digest and for circulation to the media. Other publicity materials like calendars, stickers, exhibition posters were also designed , printed and distributed by DESIDOC. It also participated in 'DRDO Exposition' held at Pragati Maida n, New Delhi from 13-29 Jan 1984.

  8. Electrodeposition of silver nanodendrites

    Energy Technology Data Exchange (ETDEWEB)

    Kaniyankandy, Sreejith [Chemistry Division, Bhabha Atomic Research Centre, Mumbai (India); Nuwad, J [Chemistry Division, Bhabha Atomic Research Centre, Mumbai (India); Thinaharan, C [Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai (India); Dey, G K [Materials Science Division, Bhabha Atomic Research Centre, Mumbai (India); Pillai, C G S [Chemistry Division, Bhabha Atomic Research Centre, Mumbai (India)

    2007-03-28

    Nanodendrites of silver were synthesized by electrodeposition using AgNO{sub 3} as the source in ammoniacal solution. The method was remarkably fast, simple and scalable. X-ray diffraction (XRD) studies confirmed the formation of a cubic phase of silver. Scanning electron microscopy (SEM) revealed the formation of well-shaped dendrites. The nanodendrites were hyperbranched with lengths of the order of a few micrometres. The concentration of NH{sub 3} in the electrolyte solution was found to have remarkable influence on the morphology, crystallite size and formation of branched nanodendrites. The branchings were found to occur at regular intervals of {approx}50 nm along the main stem. Transmission electron microscopy (TEM) studies confirmed the SEM observation and revealed the 2D nature of the dendrites. Selected area electron diffraction (SAED) revealed that the dendrites were single crystalline in nature and the branching could have a crystalline origin. The direction of growth as inferred from SAED was <110>. UV-vis spectra showed a single broad band centred on {approx}380 nm indicating the spherical shape of the individual crystallites. The intrinsic size effect of the metal surface plasmon was used to explain the increase in the broadening on addition of NH{sub 3}. The asymmetry of the band was explained on the basis of agglomeration of crystallites. The nanodendrites prepared by this method showed extension of the plasmon band through the entire visible region, indicating potential use in detection of single molecules based on enhanced Raman scattering. The deposition mechanism is described using the diffusion-limited aggregation model.

  9. Silver metallization stability and reliability

    CERN Document Server

    Adams, Daniel; Mayer, James W

    2007-01-01

    Anyone involved in circuit technology will find this an absolute must-read. It's the first book to discuss the current understanding of silver metallization and its potential as a future interconnect material for integrated circuit technology.

  10. Discovery of the Silver Isotopes

    OpenAIRE

    Schuh, A.; A. Fritsch; Ginepro, J. Q.; Heim, M.; SHORE, A.; Thoennessen, M

    2009-01-01

    Thirty-eight silver isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  11. Long-term landscape patterns of past fire events in a montane ponderosa pine forest of central Colorado

    OpenAIRE

    Brown, P. M.; Kaufmann, M. R.; Sheppard, W. D.

    1999-01-01

    Parameters of fire regimes, including fire frequency, spatial extent of burned areas, fire severity, and season of fire occurrence, influence vegetation patterns over multiple scales. In this study, centuries-long patterns of fire events in a montane ponderosa pine – Douglas-fir forest landscape surrounding Cheesman Lake in central Colorado were reconstructed from fire-scarred trees and inferences from forest stand ages. We crossdated 153 fire-scarred trees from an approximately 4000 ha study...

  12. 78 FR 19296 - Notice of Inventory Completion: History Colorado, formerly Colorado Historical Society, Denver, CO

    Science.gov (United States)

    2013-03-29

    ... Society, Denver, CO AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: History Colorado, formerly Colorado Historical Society, has completed an inventory of human remains, in consultation with the... time of the excavation and removal of these human remains, the land from which the remains and...

  13. 78 FR 30737 - Irish Potatoes Grown in Colorado; Reestablishment of Membership on the Colorado Potato...

    Science.gov (United States)

    2013-05-23

    ... action was published in the Federal Register on February 11, 2013 (78 FR 9629). An internet link to the... Service 7 CFR Part 948 Irish Potatoes Grown in Colorado; Reestablishment of Membership on the Colorado Potato Administrative Committee, Area No. 2 AGENCY: Agricultural Marketing Service, USDA. ACTION:...

  14. PIXE analysis of medieval Romanian silver coins

    International Nuclear Information System (INIS)

    The proton induced X-ray emission (PIXE) method is well suited for quick quantitative analysis of surface layers of thick metal alloys, like the silver coins (Romanian, XIVth century) reported here. No measurement with calibration standards is necessary since the elemental composition is deduced directly from known X-ray production cross sections, by correcting for proton energy loss, X-ray attenuation in the sample and detector efficiency; the correction for the secondary X-ray fluorescence was also included. A 3 MeV proton beam delivered by the tandem accelerator in Bucharest struck the silver coin oriented at 45 angle to the beam direction and the X-ray spectra have been taken with a Si(Li) detector at 90 angle relative to the beam direction. The correction scheme developed in this paper can be applied to the quantitative analysis of major constituents assuming that all elements could be detected in the spectra (in our conditions, having an atomic number Z≥15) and they have a homogeneous distribution over the projectile range. The primary X-ray yield of an element dependent on its abundance has been described considering the X-ray production cross sections for the decreasing energy of the projectile and the attenuation of the X-rays leaving the sample in the direction of the detector. The enhancement of the X-rays of those elements having absorption edges just below the emission energies of dominant elements was taken into account, although it gave only a small contribution in our case. Apart from Ag, other analyzed major elements were Cu, Pb, Au, Fe and Pt. The analysis procedure was checked with some thick Cu-Ag samples of known composition. (authors)

  15. Changes in Colorado Subalpine Fen Peat Stratigraphy and Humification During the Holocene

    Science.gov (United States)

    Sullivan, D. G.

    2013-12-01

    depositional environments, only returning to peat accumulation when cooler/moister conditions reestablished. This stratigraphic change is similar to that found by other researchers working in the Sierra Nevada, California. Higher elevation fens in Colorado persisted as peatlands throughout the Holocene, but warmer periods produced higher rates of peat accumulation and greater humification during these intervals. Peat humifiation and stratigraphic analyses indicate that the subalpine fens in Colorado preserve a sensitive record of Holocene climate change and ecohydrological conditions. Our results suggest that warmer summers over the next century will likely result in earlier snowmelt and the potential loss of lower elevation fens, and changes in peat accumulation in higher elevation fens in the subalpine zone. These changes will have significant impacts on water quality and hydrology in Colorado.

  16. Cycles of Silver

    OpenAIRE

    Dennis O. Flynn; Arturo Giráldez

    2002-01-01

    Absent a workable definition of the term ‘globalization’, debates today lack intellectual rigor. Most consider globalization a 20th-century (even post-1945) phenomenon. In fact, globalization was born when Manila was founded as a Spanish entrepôt in 1571. Connections across the Pacific Ocean (one third of Earth’s surface area) finally linked Asia with the Americas (about another third of the globe); American linkages with the Afro-Eurasian ‘Old World’ (approximately one third of Earth’s surfa...

  17. Distribution of silver in rats following 28 days of repeated oral exposure to silver nanoparticles or silver acetate

    OpenAIRE

    Mortensen Alicja; Vogel Ulla; Gao Xueyun; Larsen Agnete; Qvortrup Klaus; Hadrup Niels; Loeschner Katrin; Lam Henrik; Larsen Erik H

    2011-01-01

    Abstract Background The study investigated the distribution of silver after 28 days repeated oral administration of silver nanoparticles (AgNPs) and silver acetate (AgAc) to rats. Oral administration is a relevant route of exposure because of the use of silver nanoparticles in products related to food and food contact materials. Results AgNPs were synthesized with a size distribution of 14 ± 4 nm in diameter (90% of the nanoparticle volume) and stabilized in aqueous suspension by the polymer ...

  18. Thermally induced morphological transition of silver fractals

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Solov'yov, Andrey; Kébaili, Nouari;

    2014-01-01

    We present both experimental and theoretical study of thermally induced morphological transition of silver nanofractals. Experimentally, those nanofractals formed from deposition and diffusion of preformed silver clusters on cleaved graphite surfaces exhibit dendritic morphologies that are highly...

  19. Silver(I) imidazole perchlorate

    International Nuclear Information System (INIS)

    The crystal structure of silver(I) imidazole perchlorate reveals the presence of a planar (Ag+)6 cluster, in which three radiating pairs of Ag+ ions 3.051(1) A apart are disposed on the corners of an equilateral triangle, the inner Ag+ ions being 3.493(1) A apart. Each silver ion carries two linearly co-ordinated imidazole ligands, the whole unit has 32 (D3) symmetry. Exposure to 60Co γ-rays at 77 K results in electron addition to a group of three equivalent silver atoms. The 109Ag, 107Ag, and 14N hyperfine coupling constants show that the total 5s character of the unpaired electron is only ca. 0.55, and delocalisation onto six equivalent nitrogen ligands accounts for ca. 0.25. Low g values suggest that the remaining spin density is in 5p orbitals on silver. There is no indication of delocalisation onto the remaining three Ag+ ions in the cluster. Possible reasons for this selectivity are discussed. The electron-loss centre appears to be a normal Ag2+ complex. It is suggested that marked distortion results in the hole being trapped on one silver rather than being delocalised. (author)

  20. 21 CFR 73.2500 - Silver.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... agglomeration of crystals and the formation of amorphous silver. (2) Color additive mixtures of silver...

  1. Fluorescent silver nanoclusters stabilized by DNA scaffolds.

    Science.gov (United States)

    Yuan, Zhiqin; Chen, Ying-Chieh; Li, Hung-Wen; Chang, Huan-Tsung

    2014-09-01

    Fluorescent silver nanoclusters, in particular DNA stabilized (templated) silver nanoclusters, have attracted much attention because of their molecule-like optical properties, strong fluorescence and good biocompatibility. In this feature article, we summarize the DNA stabilized silver nanoclusters from the viewpoints of synthesis, optical properties, as well as recent applications in biological detection and imaging. PMID:24901353

  2. Mechanisms of Silver Nanoparticle Toxicity

    DEFF Research Database (Denmark)

    Foldbjerg, Rasmus

    rendering them potentially more reactive than larger particles. Accordingly, there are strong indications that particle surface area and surface chemistry are responsible for observed responses in cell cultures and animals. Silver nanoparticles (Ag NPs) are among the most commonly utilized nanomaterials due...... environment. Specific concerns have been raised about the possible toxicity of engineered nanoparticles (NPs) supported by studies which indicated that NPs are more toxic than larger particles on a mass for mass basis. As a consequence of their small size, NPs have a very high surface to volume ratio...... profiling and 32P postlabeling. Several lines of evidence indicated that both Ag NPs and silver ions from silver nitrate were able to induce cell death by apoptosis in correlation to increased levels of reactive oxygen species (ROS). The mechanism of cell death was related to loss of mitochondrial membrane...

  3. Some metallurgical aspects of ancient silver coins discovered in Romania - originals and imitations

    International Nuclear Information System (INIS)

    The paper presents an extensive archaeometrical study of two categories of ancient silver coins - Apollonia and Dyrrachium silver drachmae and Dacian drachamae. The coins of the former type were emitted by the-above mentioned Greek colonies which were under Pompejus authority during Ist Century B.C., while the latter type were Dacian imitations of the coins emitted by the Macedonian king Phillip II. All analyzed coins circulated in Dacia during the Ist Century B.C.; they were found on the territory of present Romania. As an explanation for the presence of a large number of Apollonia and Dyrrachium drachmae on the Dacian territory, it was speculated that these coins were used by Pompejus as a payment for the Dacian mercenaries fighting in the civil war on his side. To determine the elemental composition of the coins, two analytical methods were employed: Energy Dispersive X-Ray Fluorescence (ED-XRF) based on radioactive source excitation (241Am and 238Pu) and in-vacuum 3 MeV Proton Induced X-ray Emission (PIXE). For Apollonia and Dyrrachium drachmae, the following types of coins were found: original coins, debased coins (silver content down to 70%), official counterfeits - coins minted with the original dies - made out of bronze, official counterfeits of tin, and plated coins - bronze core covered with a 0.2-0.5 mm silver layer. For the Dacian drachmae, an interesting evolution of the tin content was put in evidence.. (Author)

  4. An analysis of silver candlesticks from a casting point of view: originals,copies, forgeries

    Directory of Open Access Journals (Sweden)

    Jaromir Audy

    2010-02-01

    Full Text Available Collecting silver artefacts has traditionally been a very popular hobby. Silver is addictive, therefore the number of potential collectors and investors appears to grow each year. Unfortunately, increases in the interest and buying potentials resulted in a number of forgeries manufactured and introduced to the open antique market. The items such as early silver candlesticks dictate a very high price, for many high quality fakes show very good appearances and matching similarities with originals. Such copies are traditionally manufactured by casting using the original items as patterns. Small details and variances in design features, position and shape of hallmarks, including the final surface quality are usual features to distinguish the fakes from the originals. This paper presents results of a study conducted on several silver candlesticks, including two artefacts bearing features of those produced in the mid 18th century, one original Italian candelabrum from Fascist era, and small candlesticks made in the early 20th century. Also, the paper presents some interesting contemporary coins ?replicas of many those produced in different countries. The coins were offered for sale by unscrupulous dealers via auctions and e-bays. Finally the main results and findings from this study are discussed from a manufacturing point of view, such as fabrication technology, surface quality and hallmarks, which will help the collectors, dealers and investors to detect and avoid forgeries.

  5. Regional geophysical investigations in central Colorado Plateau

    International Nuclear Information System (INIS)

    Gravity and aeromagnetic surveys covering about 15,000 square miles in the central Colorado Plateau in Utah, Colorado, Arizona, and New Mexico were conducted to assist in determining the regional subsurface geology as it may relate to uranium, oil, and potash exploration. The dominant gravity anomalies are conspicuous gravity lows over the salt anticlines. Both broad regional highs, which occur over the monoclinal uplifts where denser rocks are close to the surface, and regional lows, which occur over the basin and platform areas, are caused by lateral density contrasts related to structural relief. Most of the magnetic anomalies arise from contrasts in magnetization of the Precambrian basement

  6. Migration of photogenerated charge carriers in silver halides: small polaron transport

    OpenAIRE

    Georgiev, Mladen

    2009-01-01

    Nearly half a century ago, I joined an ambitious research project aimed at establishing the mechanism of photodecomposition of ionic salts. We measured the mobilities and lifetimes of photoelectrons and photoholes in silver bromide in order to get an early-stage knowledge of the process. The last pairs of quantities to study were the diffusion coefficients for which we got results, highly controversial at that time. Now we show that the diffusion data suggest the formation of itinerant Jahn T...

  7. Using pixel and object based IKONOS image analysis for studying decay in silver fir stands

    OpenAIRE

    Ionut Barnoaiea; Ovidiu Iacobescu

    2009-01-01

    The problem of old silver fir stands decay has appeared in the last decades of the last century with symptoms such as defoliation, wood decay and parasites attacks. The problems in monitoring this phenomenon is that the defoliation and mistletoe attack appear on the crown top, triggering the coronation process - tree develop branches on their lower stem part in order to resist to the defoliation. This reaction makes the attack difficult to notice on aerial or satellite images, due to the refl...

  8. Formation of Professional Identity at the New Silver Street Kindergarten, 1883

    OpenAIRE

    Adams, Kathleen

    2006-01-01

    This study focuses on the linguistic strategies utilized by women of the 19th century kindergarten movement in the United States to establish a professional identity within a dominant discourse of separate spheres based on gender. This project takes the form of a case study of the Silver Street Kindergarten in San Francisco and is based on an annual report that records a transitional moment where practitioners took control of the organization by introducing their emerging professional identit...

  9. No silver bullet in international development

    Directory of Open Access Journals (Sweden)

    Fabio Daneri

    2016-07-01

    Full Text Available Development economics has started to propose solutions to the problem of development in underdeveloped countries since the 17th century. Over time, various solutions have been proposed by many different development researchers and economists. Most of these solutions have the common characteristic of looking for a so-called “silver bullet” to the problem of development, that is to say a single solution to be applied to all underdeveloped countries, which over time might be freedom, foreign aid, good governance or other single approach. The purpose of this paper is to argue that, being development generally intended as a sort of “adequate level of production of goods and services by public and private subjects in a given country”, the solution to the problem of development cannot be a single one, given that the basic theory of production in economics in based on 4 factors of production (entrepreneurship, labor, capital and land, so that the level and quality of these 4 factors and all the sub-factors influencing them (such as the climate in the case of land or the culture in the case of entrepreneurship will be the real responsible for the development process in a country.

  10. Antituberculous effect of silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kreytsberg, G N; Gracheva, I E [Limited Liability Company ' Scientific and Production Association (NPO)' Likom' , 150049, Yaroslavl, Magistralnaya str., 32 (Russian Federation); Kibrik, B S [Yaroslavl State Medical Academy Russia, 150000, Yaroslavl, Revolutsionnaya str., 5 (Russian Federation); Golikov, I V, E-mail: likomm@yaroslavl.ru [Yaroslavl State Technical University Russia, 150023, Yaroslavl, Moskovskiy avenue, 88 (Russian Federation)

    2011-04-01

    The in vitro experiment, involving 1164 strains of the tuberculosis mycobacteria, exhibited a potentiating effect of silver nanoparticles on known antituberculous preparations in respect of overcoming drug-resistance of the causative agent. The in vitro experiment, based on the model of resistant tuberculosis, was performed on 65 white mice. An evident antituberculous effect of the nanocomposite on the basis of silver nanoparticles and isoniazid was proved. Toxicological assessment of the of nanopreparations was carried out. The performed research scientifically establishes efficacy and safety of the nanocomposite application in combination therapy of patients suffering from drug-resistant tuberculosis.

  11. Prevalence of neutralizing antibodies to rabies virus in serum of seven species of insectivorous bats from Colorado and New Mexico, United States

    Science.gov (United States)

    Bowen, Richard A.; O'Shea, Thomas J.; Shankar, Vidya; Neubaum, Melissa A.; Neubaum, Daniel J.; Rupprecht, Charles E.

    2013-01-01

    We determined the presence of rabies-virus-neutralizing antibodies (RVNA) in serum of 721 insectivorous bats of seven species captured, sampled, and released in Colorado and New Mexico, United States in 2003-2005. A subsample of 160 bats was tested for rabies-virus RNA in saliva. We sampled little brown bats (Myotis lucifugus) at two maternity roosts in Larimer County, Colorado; big brown bats (Eptesicus fuscus) at three maternity roosts in Morgan County, Colorado; and big brown bats at five maternity roosts in Larimer County. We also sampled hoary bats (Lasiurus cinereus) and silver-haired bats (Lasionycteris noctivagans) captured while drinking or foraging over water in Bernalillo County, New Mexico and at various locations in Larimer County. Big brown bats, little brown bats, long-legged myotis (Myotis volans), long-eared myotis (Myotis evotis), and fringed myotis (Myotis thysanodes) were also sampled over water in Larimer County. All species except long-eared myotis included individuals with RVNA, with prevalences ranging from 7% in adult female silver-haired bats to 32% in adult female hoary bats. None of the bats had detectable rabies-virus RNA in oropharyngeal swabs, including 51 bats of 5 species that had RVNA in serum. Antibody-positive bats were present in nine of the 10 maternity colonies sampled. These data suggest that wild bats are commonly exposed to rabies virus and develop a humoral immune response suggesting some degree of viral replication, but many infections fail to progress to clinical disease.

  12. The Colorado Lightning Mapping Array

    Science.gov (United States)

    Rison, W.; Krehbiel, P. R.; Thomas, R. J.; Rodeheffer, D.; Fuchs, B.

    2012-12-01

    A fifteen station Lightning Mapping Array (LMA) was installed in northern Colorado in the spring of 2012. While the driving force for the array was to produce 3-dimensional lightning data to support the Deep Convective Clouds and Chemistry (DC3) Experiment (Barth, this conference), data from the array are being used for several other projects. These include: electrification studies in conjunction with the CSU CHILL radar (Lang et al, this conference); observations of the parent lightning discharges of sprites (Lyons et al, this conference); trying to detect upward discharges triggered by wind turbines, characterizing conditions in which aircraft flying through clouds produce discharges which can be detected by the LMA, and other opportunities, such as observations of lightning in pyrocumulus clouds produced by the High Park Fire west of Fort Collins, CO. All the COLMA stations are solar-powered, and use broadband cellular modems for data communications. This makes the stations completely self-contained and autonomous, allowing a station to be installed anywhere a cellular signal is available. Because most of the stations were installed well away from anthropogenic noise sources, the COLMA is very sensitive. This is evidenced by the numerous plane tracks detected in its the vicinity. The diameter, D, of the COLMA is about 100 km, significantly larger than other LMAs. Because the error in the radial distance r is proportional to (r/D)2, and the error in the altitude z is proportional to (z/D)2, the larger array diameter greatly expands the usable range of the COLMA. The COLMA is able to detect and characterize lighting flashes to a distance of about 350 km from the array center. In addition to a web-based display (lightning.nmt.edu/colma), geo-referenced images are produced and updated at one-minute intervals. These geo-referenced images can be used to overlay the real-time lightning data on Google Earth and other mapping software. These displays were used by the DC3

  13. Silver-Palladium Surfaces Inhibit Biofilm Formation

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Schroll, Casper; Hilbert, Lisbeth Rischel;

    2009-01-01

    Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition...... efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver...

  14. A Century of Acoustic Metrology

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect.......The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect....

  15. Molybdenite in the Montezuma District of central Colorado

    Science.gov (United States)

    Neuerburg, George J.; Botinelly, Theodore; Watterson, John R.

    1974-01-01

    The Montezuma mining district, in the Colorado mineral belt, is defined by an assemblage of porphyry, ore, and altered rocks that originated in the venting of a Tertiary batholith through weak structures in Precambrian rocks. The ore consists of silver-lead-zinc veins clustered on the propylitic fringe of a geometrically complex system of altered rocks, which is centered on the intersection of the Oligocene Montezuma stock with the Montezuma shear zone of Precambrian ancestry. Alteration chemistry conforms to the standard porphyry-metal model but is developed around several small intrusives strung out along the shear zone and is expressed as a mottled pattern, rather than as the usual thick concentric zones centered on one large plug. The distribution of trace amounts of molybdenite is consistent with the postulate of molybdenite deposits in the district, but the mottled alteration pattern may signify small and scattered, possibly very deep, deposits. Disseminated molybdenite is essentially coextensive with altered rock and increases slightly in quantity toward the inner alteration zones. Two groups of molybdenite veins, associated with phyllic and potassic alteration, represent possible diffuse halos of molybdenite deposits. One group of veins resembles the Climax and Henderson deposits but was seen only in a small and isolated area of outcrops. The second group of molybdenite veins is in a bismuth-rich part of the Montezuma stock and underlies an area of bismuth veins; this group records the passage of contact metasomatic ore fluids. Another bismuth-rich area is in the southeast corner of the stock in a region of bismuth veins and may indicate a third group of molybdenite veins.

  16. Gravimetric and volumetric determination of the purity of electrolytically refined silver and the produced silver nitrate

    Directory of Open Access Journals (Sweden)

    Ačanski Marijana M.

    2007-01-01

    Full Text Available Silver is, along with gold and the platinum-group metals, one of the so called precious metals. Because of its comparative scarcity, brilliant white color, malleability and resistance to atmospheric oxidation, silver has been used in the manufacture of coins and jewelry for a long time. Silver has the highest known electrical and thermal conductivity of all metals and is used in fabricating printed electrical circuits, and also as a coating for electronic conductors. It is also alloyed with other elements such as nickel or palladium for use in electrical contacts. The most useful silver salt is silver nitrate, a caustic chemical reagent, significant as an antiseptic and as a reagent in analytical chemistry. Pure silver nitrate is an intermediate in the industrial preparation of other silver salts, including the colloidal silver compounds used in medicine and the silver halides incorporated into photographic emulsions. Silver halides become increasingly insoluble in the series: AgCl, AgBr, AgI. All silver salts are sensitive to light and are used in photographic coatings on film and paper. The ZORKA-PHARMA company (Sabac, Serbia specializes in the production of pharmaceutical remedies and lab chemicals. One of its products is chemical silver nitrate (argentum-nitricum (l. Silver nitrate is generally produced by dissolving pure electrolytically refined silver in hot 48% nitric acid. Since the purity of silver nitrate, produced in 2002, was not in compliance with the p.a. level of purity, there was doubt that the electrolytically refined silver was pure. The aim of this research was the gravimetric and volumetric determination of the purity of electrolytically refined silver and silver nitrate, produced industrially and in a laboratory. The purity determination was carried out gravimetrically, by the sedimentation of silver(I ions in the form of insoluble silver salts: AgCl, AgBr and Agi, and volumetrically, according to Mohr and Volhardt. The

  17. Influence of injected silver content on synthesis of silver coated nickel particles by DC thermal plasma

    Science.gov (United States)

    Park, Si Taek; Kim, Tae-Hee; Park, Dong-Wha

    2016-06-01

    Silver nanoparticle-coated spherical nickel particles were prepared from a mixture of micro-sized silver and nickel as raw materials by DC thermal plasma treatment. The mixture of micro-sized silver and nickel powders was injected into the high-temperature region of an argon thermal plasma jet. Although the silver, with its very high thermal conductivity and relatively low boiling point, was thoroughly evaporated by this process, nickel was not evaporated perfectly because of its comparatively low thermal conductivity and high boiling point. The rough nickel powder was spheroidized as it melted. Finally, silver evaporated by the thermal plasma quickly condensed into nanoparticles on the surfaces of the micro-sized spherical nickel particles, aided by the sharp temperature gradient of the thermal plasma jet. With varying the ratios of silver to nickel feedstock from 1:10 to 5:1, the products synthesized in each condition were examined by XRD, XPS, FE-SEM, and FE-TEM. More silver nanoparticles were attached on the nickel by increasing the injected feedstock to 9.8 at% silver. Meanwhile, a decrease of silver in the products was observed when larger amounts of silver were introduced to the thermal plasma jet. The exposed silver components decreased with greater proportions of silver feedstock because of the metal's dendritic structure and the formation of silver-coated silver particles.

  18. Statisticians of the centuries

    CERN Document Server

    Seneta, E; Crépel, P; Fienberg, S; Gani, J

    2001-01-01

    Statisticians of the Centuries aims to demonstrate the achievements of statistics to a broad audience, and to commemorate the work of celebrated statisticians. This is done through short biographies that put the statistical work in its historical and sociological context, emphasizing contributions to science and society in the broadest terms rather than narrow technical achievement. The discipline is treated from its earliest times and only individuals born prior to the 20th Century are included. The volume arose through the initiative of the International Statistical Institute (ISI), the principal representative association for international statistics (founded in 1885). Extensive consultations within the statistical community, and with prominent members of ISI in particular, led to the names of the 104 individuals who are included in the volume. The biographies were contributed by 73 authors from across the world. The editors are the well-known statisticians Chris Heyde and Eugene Seneta. Chris Heyde is Pro...

  19. Hospital Based Paternity Establishment in Colorado.

    Science.gov (United States)

    Pearson, Jessica; Thoennes, Nancy

    1997-01-01

    Describes the impact of the Colorado's Child Support Improvement Project on voluntary paternity acknowledgment rate, which increased almost 24% from 1991 to 1994. Program activities include simplifying voluntary acknowledgment procedures and training hospital personnel on paternity. Voluntary paternity acknowledgment is associated with the…

  20. Besnoitiosis in rodents from Colorado. [Parasitic infestations

    Energy Technology Data Exchange (ETDEWEB)

    Dagle, G E; Winsor, T F; Adee, R R

    1976-01-01

    Parasitic cysts of Besnoitia jellisoni (coccidia) were found in rodents (Peromyscus maniculatus and Spermophilus tridecemlineatus) trapped in Eastern Colorado. The parasite was associated with a granulomatous inflammatory reaction in the lungs of each rodent and was disseminated in several organs from one Peromyscus. The ultrastructural appearance of the merozoites and the cyst wall formed by the host cell were studied.

  1. Bats of the Colorado oil shale region

    Energy Technology Data Exchange (ETDEWEB)

    Finley, R.B. Jr.; Caire, W.; Wilhelm, D.E.

    1984-10-31

    New records for Myotis californicus, M. evotis, M. leibii, M. lucifugus, M. thysanodes, M. volans, M. yumanensis, Lasionycteris noctivagans, Pipistrellus hesperus, Eptesicus fuscus, Lasiurus cinereus, Plecotus townsendii, and Antrozous pallidus and their habitat occurrence in northwestern Colorado are reported. Mortality of 27 bats of six species trapped in an oil sludge pit is described. 7 references.

  2. Denver, Colorado: Solar in Action (Brochure)

    Energy Technology Data Exchange (ETDEWEB)

    2011-10-01

    This brochure provides an overview of the challenges and successes of Denver, Colorado, a 2008 Solar America City awardee, on the path toward becoming a solar-powered community. Accomplishments, case studies, key lessons learned, and local resource information are given.

  3. 78 FR 57923 - Colorado Disaster #CO-00065

    Science.gov (United States)

    2013-09-20

    ... ADMINISTRATION Colorado Disaster CO-00065 AGENCY: Small Business Administration. ACTION: Notice. SUMMARY: This is... applications to: U.S. Small Business Administration, Processing and Disbursement Center, 14925 Kingsport Road.... Small Business Administration, 409 3rd Street SW., Suite 6050, Washington, DC 20416....

  4. Air quality management in Denver, Colorado

    International Nuclear Information System (INIS)

    The state of Colorado is addressing a number of air quality problems. In addition to carbon monoxide, ozone, particulates, nitrogen dioxide, sulfur dioxide, and lead, they are also designing programs to deal with visibility, acid deposition, ozone depletion, and global warming. Programs for controlling carbon monoxide, particulates, vehicle emissions, and programs for achieving lifestyle changes are discussed in particular

  5. Colorado Academic Library Master Plan. Revised Edition.

    Science.gov (United States)

    Johns, Claude, Jr., Ed.; Moore, Beverly, Ed.

    This master plan for Colorado academic libraries assesses current strengths and weaknesses of public and private academic libraries in the state and forecasts the role of academic libraries in support of higher education. The plan consists of a series of recommendations divided into six related and overlapping sections: access, collection…

  6. A Century of Antivenom

    OpenAIRE

    Lovreček, Dijana; Tomić, Siniša

    2011-01-01

    Because it primarily affects the poor in undeveloped parts of the world where medical care is often inadequate and insufficient, envenomation is considered a neglected public health issue, despite the existence of antivenom therapy for more than a century. This article provides an overview of the epidemiological situation for important venomous animals, together with achievements in the production, control, technological progress and safety of antivenoms since their discovery.

  7. WHEELING THROUGH THE CENTURIES

    Institute of Scientific and Technical Information of China (English)

    HUO; JIANYING

    2002-01-01

    IN an excavated pit at the side of an expressway in Shandong’s Linzi are visible 2,000-year-old remains of horses and wooden carriages. The horse skeletons are on their side, in an attitude of motion. The pit was discovered in the late 20th century, when the expressway was being built. These early ancestors of modern transport, no longer "road-worthy," are now protected historic artifacts.

  8. Identifying 21st Century Capabilities

    Science.gov (United States)

    Stevens, Robert

    2012-01-01

    What are the capabilities necessary to meet 21st century challenges? Much of the literature on 21st century skills focuses on skills necessary to meet those challenges associated with future work in a globalised world. The result is a limited characterisation of those capabilities necessary to address 21st century social, health and particularly…

  9. Conducting polymer-silver composites

    Czech Academy of Sciences Publication Activity Database

    Stejskal, Jaroslav

    2013-01-01

    Roč. 67, č. 8 (2013), s. 814-848. ISSN 0366-6352 R&D Projects: GA TA ČR TE01020022 Institutional support: RVO:61389013 Keywords : polyaniline * polypyrrole * silver Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.193, year: 2013

  10. Antimicrobial Properties of a Novel Silver-Silica Nanocomposite Material▿

    Science.gov (United States)

    Egger, Salome; Lehmann, Rainer P.; Height, Murray J.; Loessner, Martin J.; Schuppler, Markus

    2009-01-01

    Nanotechnology enables development and production of novel silver-based composite materials. We used in vitro tests to demonstrate the antimicrobial activity of a silver-silica nanocomposite compared to the activities of conventional materials, such as silver nitrate and silver zeolite. A silver-silica-containing polystyrene material was manufactured and shown to possess strong antimicrobial properties. PMID:19270121

  11. Plasmon enhanced silver quantum cluster fluorescence for biochemical applications

    DEFF Research Database (Denmark)

    Bernard, S.; Kutter, Jörg P.; Mogensen, K. B.

    2014-01-01

    Fluorescence microscopy of individual silver quantum clusters on the surface of silver nanoparticles reveals strong photoactivated emission under blue light excitation [1-4]. In this work, silver nanoparticles are produced by annealing silver thin films deposited on a glass substrate and silver q...

  12. Antimicrobial Properties of a Novel Silver-Silica Nanocomposite Material▿

    OpenAIRE

    Egger, Salome; Lehmann, Rainer P.; Height, Murray J.; Loessner, Martin J; Schuppler, Markus

    2009-01-01

    Nanotechnology enables development and production of novel silver-based composite materials. We used in vitro tests to demonstrate the antimicrobial activity of a silver-silica nanocomposite compared to the activities of conventional materials, such as silver nitrate and silver zeolite. A silver-silica-containing polystyrene material was manufactured and shown to possess strong antimicrobial properties.

  13. Conductive silver patterns via ethylene glycol vapor reduction of ink-jet printed silver nitrate tracks on a polyimide substrate

    International Nuclear Information System (INIS)

    In this paper, we report using ethylene glycol vapor reduction approach to fabricate conductive silver tracks directly from silver nitrate solution by ink-jet printing. The silver nitrate precursor can be reduced in ethylene glycol vapor to form silver at low temperatures. X-ray diffraction, thermogravimetric analysis, and energy dispersive spectrometric analysis results indicate that the silver nitrate has been converted to silver completely. Using a high concentration silver nitrate solution, continuous silver conductive lines with a resistivity of 7.314 x 10-5 Ω cm have been produced, which is relatively close to the resistivity of bulk silver.

  14. Facile Preparation of Silver Nanoparticles and Application to Silver Coating Using Latent Reductant from a Silver Carbamate Complex

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyunga; Cha, Jaeryung; Gong, Myoungseon [Dankook Univ. Graduate School, Chungnam (Korea, Republic of)

    2013-02-15

    A low temperature (65 .deg. C) thermal deposition process was developed for depositing a silver coating on thermally sensitive polymeric substrates. This low temperature deposition was achieved by chemical reduction of a silver alkylcarbamate complex with latent reducing agent. The effects of acetol as a latent reducing agent for the silver 2-ethylhexylcarbamate (Ag-EHCB) complex and their blend solutions were investigated in terms of reducing mechanism, and the size and shape of silver nanoparticles (Ag-NPs) as a function of reduced temperature and time, and PVP stabilizer concentration were determined. Low temperature deposition was achieved by combining chemical reduction with thermal heating at 65 .deg. C. A range of polymer film, sheet and molding product was coated with silver at thicknesses of 100 nm. The effect of process parameters and heat treatment on the properties of silver coatings was investigated.

  15. The quantum century

    International Nuclear Information System (INIS)

    Physicists often complain that the phrase quantum leap'' is used erroneously, if harmlessly, by people to describe a large jump or change. Yet this month the physics community is celebrating the 100th anniversary of what must count as the beginning of the biggest quantum leap in the history of science, whichever way you define the phrase. On 14 December 1900 Max Planck presented a paper on the radiation emitted by a black body at a meeting of the German Physical Society in Berlin. This event is generally taken to mark the start of the quantum century, though few people realized it at the time - not even Planck himself. (U.K.)

  16. New Century, New Prospects

    Institute of Scientific and Technical Information of China (English)

    CHEN XULONG

    2010-01-01

    @@ Nuclear weapons changed the world of the 20th century. Their powerful force rewrote history. Nuclear bombs dropped on Japan by the United States accelerated the collapse of Japanese militarism and hastened the end of World War Ⅱ. The West led by the United States and the East bloc led by the Soviet Union started a bitter nuclear arms race that mutually assured destruction. The balance of terror between the two blocs stabilized in the Cold War and prevented the world from actual armed conflict, thus maintaining a long-term but occasionally uneasy peace in Europe and the world.

  17. A Century Apart

    OpenAIRE

    Birgir Hrannar Stefánsson 1982

    2014-01-01

    Iceland and China are two nations situated almost at the opposite side of the globe. In this thesis, I am taking two examples of media coverage on China; the writings of Ólafur Ólafsson are compared with the discussion in Akureyri Vikublað regarding Huang Nubo. Ólafur Ólafsson was a pioneer of intercultural communication between Iceland and China in the early 20th century. Working as a missionary in China he sent home letters published through the magazine Ljósberinn and later on these wr...

  18. Polyamide/silver antimicrobials: Effect of filler types on the silver ion release

    OpenAIRE

    Kumar, Radhesh; Howdle, Steve; Münstedt, Helmut

    2005-01-01

    Abstract: The efficiency of various silver-based antimicrobial fillers (elementary silver and silver substituted materials) in polyamide (PA) toward their silver ion (Ag�) release characteristics in an aqueous medium was investigated and discussed. Anode stripping voltammetry (ASV) was used for the quantitative estimation of Ag� release from these composites. The biocidal (Ag�) release from the composites was found to be dependent on the time of soaking in water and the nature ...

  19. Application of Silver and Silver Oxide Nanoparticles Impregnated on Activated Carbon to the Degradation of Bromate.

    Science.gov (United States)

    Choi, J S; Lee, H; Park, Y K; Kim, S J; Kim, B J; An, K H; Kim, B H; Jung, S C

    2016-05-01

    Silver and silver oxide nanoparticles were impregnated on the surface of powdered activated carbon (PAC) using a single-step liquid phase plasma (LPP) method. Spherical silver and silver oxide nanoparticles of 20 to 100 nm size were dipersed evenly on the surface of PAC. The impregnated PAC exhibited a higher activity for the decomposition of bromate than bare PAC. The XPS, Raman and EDX analyses showed that the Ag/PAC composites synthesized by the LPP process. PMID:27483780

  20. Silver nanocluster catalytic microreactors for water purification

    Science.gov (United States)

    Da Silva, B.; Habibi, M.; Ognier, S.; Schelcher, G.; Mostafavi-Amjad, J.; Khalesifard, H. R. M.; Tatoulian, M.; Bonn, D.

    2016-07-01

    A new method for the elaboration of a novel type of catalytic microsystem with a high specific area catalyst is developed. A silver nanocluster catalytic microreactor was elaborated by doping a soda-lime glass with a silver salt. By applying a high power laser beam to the glass, silver nanoclusters are obtained at one of the surfaces which were characterized by BET measurements and AFM. A microfluidic chip was obtained by sealing the silver coated glass with a NOA 81 microchannel. The catalytic activity of the silver nanoclusters was then tested for the efficiency of water purification by using catalytic ozonation to oxidize an organic pollutant. The silver nanoclusters were found to be very stable in the microreactor and efficiently oxidized the pollutant, in spite of the very short residence times in the microchannel. This opens the way to study catalytic reactions in microchannels without the need of introducing the catalyst as a powder or manufacturing complex packed bed microreactors.

  1. Laser-induced breakdown spectroscopy study of silversmith pieces: the case of a Spanish canopy of the nineteenth century

    Science.gov (United States)

    Gómez-Morón, M. A.; Ortiz, P.; Ortiz, R.; Martín, J. M.; Mateo, M. P.; Nicolás, G.

    2016-05-01

    Canopies of needlework velvet or silversmith pieces placed on twelve or more battens are widely employed in Spanish catholic ceremonies to cover the image of the virgin. In this paper, we focus our interest on those pieces made of silver. These silver crafts suffered a revolution in the nineteenth century with the development of an electrolyte system that can be applied over carved metal pieces, in order to obtain a silver layer by electrodeposition similar in appearance to the original sterling silver and cheaper. The aim of this research was the application of laser-induced breakdown spectroscopy (LIBS) to the study of a canopy of the nineteenth century in order to assess the techniques used for its manufacturing and the identification of replacement and restoration of original pieces. The LIBS depth profiles show the presence of a micron silver layer over an alloy of copper and zinc in most of the surfaces. Corrosion products, alloy missing, and the restoration with copper layers were detected. These results are consistent with those obtained by scanning electron microscopy with energy-dispersive of X-ray with the advantage that LIBS is a methodology that allows analysing metal pieces without sampling or preparation. In summary, LIBS is a technique that allows the study of silversmith pieces with electrochemical preparation according to the Ruolz technique, and it is also possible to detect subsequent restoration or corrosion zones.

  2. A century of physics

    CERN Document Server

    Bromley, D Allan

    2002-01-01

    In this amazing tour d'horizon, D. Allan Bromley uses the occasion of the centenary of the American Physical Society to reflect upon the growth of physics over the past 100 years, its fragmentation into numerous subdisciplines, the impact physics has had upon modern technology, and the re-emergence of the fundamental unity of the discipline in recent years. Hundreds of historical illustrations accompany the text. Bromley conveys much of the excitement and wonder that research in physics generated in the 20th century and asks what new things are in store in the next century. He covers such topics as relativity and quantum mechanics, the Manhattan project, superconductivity, transistors and the revolution brought about by solid-state electronics, protein folding, the uses of nuclear and atomic physics in biology and medicine, plate tectonics, the expansion of the universe and the Big Bang, and gravitational radiation. Bromley, the Sterling Professor of the Sciences and Dean of Yale University, served as Assista...

  3. The management century.

    Science.gov (United States)

    Kiechel, Walter

    2012-11-01

    In 1886, addressing the nascent American Society of Mechanical Engineers, Henry R. Towne proposed that "the management of works" be considered a modern art--thereby heralding the Management Century, when management as we know it came into being and shaped the world in which we work. Kiechel, a past editorial director of Harvard Business Publishing, elucidates the three eras that punctuate this period: the years leading up to World War II, during which scientific exactitude gave wings to a new managerial elite; the early postwar decades, managerialism's apogee of self-confidence and a time when wartime principles of strategy were adapted, sometimes ruthlessly, to the running of companies; and the 1980s to the present, years that saw fast-moving changes, disequilibrium, and a servitude to market forces but also ushered in globalism, unprecedented innovation, and heightened expectations about how workers are to be treated. Along the way he examines the contributions of thinkers such as Frederick Taylor, Elton Mayo, Peter Drucker, and Michael Porter. What lies ahead? Perhaps the biggest challenge facing the 21st-century company, Kiechel posits, is to truly free the spark of human imagination from the organization's tidal pull toward the status quo. There's almost always a better way, he concludes--and management will continue to seek it. PMID:23155998

  4. Gunnison, Colorado subpile study report. Revision 1

    International Nuclear Information System (INIS)

    To protect human health and the environment, the Uranium Mill Tailings Remedial Action (UMTRA) Project will remediate the uranium mill tailings site at Gunnison Colorado. There are explicit requirements (i.e., 40 CFR Part 192) for the surface remediation of radiologically contaminated soils on UMTRA sites. The removal of subpile sediment to the depth required by 40 CFR Part 192 will leave in place deeper foundation sediment that is contaminated with hazardous constituents other than radium-226 and thorium-230. The Department of Energy and the Colorado Department of Health have questioned whether this contaminated soil could potentially act as a continuing source of ground water contamination even after surface remediation based on 40 CFR Part 192 is complete. To evaluate the subpile sediments as a potential source of ground water contamination, the Gunnison Subpile study was initiated. This report summarizes the results and findings of this study

  5. Risk assessment of silver nanoparticles

    Science.gov (United States)

    Shipelin, V. A.; Gmoshinski, I. V.; Khotimchenko, S. A.

    2015-11-01

    Nanoparticles of metallic silver (Ag) are among the most widely used products of nanotechnology. Nanosized colloidal silver (NCS) is presented in many kinds of production as solutions of particles with diameter less than 100 nm. NCS is used in a variety of fields, including food supplements, medicines, cosmetics, packaging materials, disinfectants, water filters, and many others. Problems of toxicity and related safety of NCS for humans and environmental systems are recently overestimated basing on data of numerous toxicological studies in vitro and in vivo. The article discusses the results of current studies in recent years and the data of author's own experiments on studying the safety of NCS, that allows to move on to risk assessment of this nanomaterial presented in consumer products and environmental samples.

  6. 'Magnetic' phase transition in silver

    International Nuclear Information System (INIS)

    Experimental and theoretical investigations of the magnetic susceptibility near the phase transition into the Condon domain state in silver are presented. We report about the precursor of the Condon instability of an electron gas by using data of the measurement of the magnetic field-dependence of the susceptibility. Experimental results are explained theoretically within the framework of the Lifshitz-Kosevich-Shoenberg theory. A good agreement between the theory and the experiment is obtained when de Haas-van Alphen oscillations are only originated from 'belly' oscillations, and as a result of this, the spherical modelling of the Fermi surface in silver is justified. It is shown that the phase transition into the Condon domain state is the critical point of the liquid-gas type at which the isothermal susceptibility does not diverge but possesses a finite value due to the nonzero demagnetization factor

  7. Aligned Layers of Silver Nano-Fibers

    OpenAIRE

    Golovin, Andrii B.; Liubov Kreminska; Jeremy Stromer

    2012-01-01

    We describe a new dichroic polarizers made by ordering silver nano-fibers to aligned layers. The aligned layers consist of nano-fibers and self-assembled molecular aggregates of lyotropic liquid crystals. Unidirectional alignment of the layers is achieved by means of mechanical shearing. Aligned layers of silver nano-fibers are partially transparent to a linearly polarized electromagnetic radiation. The unidirectional alignment and density of the silver nano-fibers determine degree of polariz...

  8. Recycle silver metal from radiographic film waste

    International Nuclear Information System (INIS)

    The laboratory techniques described herein refer to the possible recovery of silver metal from used photographic films. Recovery of silver from x-ray film involves two steps: the separation of metallic component from the processed radiographic films (organic component), and the recovery of silver. The present paper reports a method for separating the inorganic component by treating the processed radiographic film with heated sodium hydroxide solution. (Author)

  9. Fluorescent silver nanoclusters as DNA probes

    Science.gov (United States)

    Obliosca, Judy M.; Liu, Cong; Yeh, Hsin-Chih

    2013-08-01

    Fluorescent silver nanoclusters (few atoms, quantum sized) have attracted much attention as promising substitutes for conventional fluorophores. Due to their unique environmental sensitivities, new fluorescent probes have been developed based on silver nanoclusters for the sensitive and specific detection of DNA. In this review we present the recent discoveries of activatable and color-switchable properties of DNA-templated silver nanoclusters and discuss the strategies to use these new properties in DNA sensing.

  10. Atomistic Potentials for Palladium-Silver Hydrides

    OpenAIRE

    Hale, L. M.; Wong, B. M.; Zimmerman, J. A.; Zhou, X.

    2013-01-01

    New EAM potentials for the ternary palladium-silver-hydrogen system are developed by extending a previously developed palladium-hydrogen potential. The ternary potentials accurately capture the heat of mixing and structural properties associated with solid solution alloys of palladium-silver. Stable hydrides are produced with properties that smoothly transition across the compositions. Additions of silver to palladium are predicted to alter the properties of the hydrides by decreasing the mis...

  11. Immobilization of silver nanoparticles on polyethylene terephthalate

    OpenAIRE

    Reznickova, Alena; Novotna, Zdenka; Kolska, Zdenka; Svorcik, Vaclav

    2014-01-01

    Two different procedures of grafting with silver nanoparticles (AgNP) of polyethylene terephthalate (PET), activated by plasma treatment, are studied. In the first procedure, the PET foil was grafted with biphenyl-4,4′-dithiol and subsequently with silver nanoparticles. In the second one, the PET foil was grafted with silver nanoparticles previously coated with the same dithiol. X-ray photoelectron spectroscopy and electrokinetic analysis were used for characterization of the polymer surface ...

  12. Silver staining of proteins in polyacrylamide gels

    OpenAIRE

    Chevallet, Mireille; Luche, Sylvie; Rabilloud, Thierry

    2006-01-01

    International audience Silver staining is used to detect proteins after electrophoretic separation on polyacrylamide gels. It combines excellent sensitivity (in the low nanogram range) with the use of very simple and cheap equipment and chemicals. It is compatible with downstream processing, such as mass spectrometry analysis after protein digestion. The sequential phases of silver staining are protein fixation, then sensitization, then silver impregnation and finally image development. Se...

  13. BENEFITS OF CONTROLLING SALINE WATER IN COLORADO

    OpenAIRE

    Ellingson, Lindsey; Houk, Eric E.; Schuck, Eric C.; Frasier, W. Marshall

    2004-01-01

    The Arkansas River in Colorado is confronted with a salinity issue; the majority of this salinity problem is due to agricultural runoff caused by irrigation. Reducing applications of irrigation water through adoption of more technically efficient irrigation systems is one means of improving water quality in the Arkansas River basin. This research uses positive mathematical programming to model the cropping practices of the farms along the Arkansas River. It examines the affect of acreage and ...

  14. Green pricing: A Colorado case study

    Energy Technology Data Exchange (ETDEWEB)

    Blank, E.; Udall, J.R.

    1996-12-31

    A model program for green pricing targeted primarily at large customers is proposed in this paper. The program would create a partnership between a local community group, a renewables advocacy group, and several Colorado utilities. The first part of the paper summarizes pertinent background issues, including utility experience with green pricing programs. The rest of the paper outlines the program proposal, focusing primarily on organizational structure.

  15. Microwave assisted template synthesis of silver nanoparticles

    Indian Academy of Sciences (India)

    K J Sreeram; M Nidhin; B U Nair

    2008-12-01

    Easier, less time consuming, green processes, which yield silver nanoparticles of uniform size, shape and morphology are of interest. Various methods for synthesis, such as conventional temperature assisted process, controlled reaction at elevated temperatures, and microwave assisted process have been evaluated for the kind of silver nanoparticles synthesized. Starch has been employed as a template and reducing agent. Electron microscopy, photon correlation spectroscopy and surface plasmon resonance have been employed to characterize the silver nanoparticles synthesized. Compared to conventional methods, microwave assisted synthesis was faster and provided particles with an average particle size of 12 nm. Further, the starch functions as template, preventing the aggregation of silver nanoparticles.

  16. Silver sources of archaic Greek coinage

    International Nuclear Information System (INIS)

    The authors report on new chemical and lead isotopic results and interpretations of archaic Greek silver coins from the Asyut hoard which was buried around 475 B.C. Aeginetan coins were of central interest in this study. Possible ancient silver mines were explored in the Aegean region in the course of several geologic expeditions, and chemically and isotopically investigated. Some of the silver sources in Greece were traced by combination of the analytical methods and questions of provenance were solved. In addition, processes of silver smelting and refining were studied. Results and implications of this work are summarized in the final section on Conclusions. (orig.)

  17. XPS and XRF depth patina profiles of ancient silver coins

    International Nuclear Information System (INIS)

    Ancient silver coins of different historical periods going from IV cent. B.C. up to recent XIX century, coming from different Mediterranean countries have been investigated with different surface physical analyses. X-ray photoelectron spectroscopy (XPS) analysis has been performed by using electron emission induced by 1.4 keV X-rays. X-ray fluorescence (XRF) analysis has been devoted by using 30 keV electron beam. Scanning electron microscopy (SEM) has been employed to analyze the surface morphology and the X-ray map distribution by using a 30 keV microbeam. Techniques were used to investigate about the patina composition and trace elements as a function of the sample depth obtained coupling XPS to 3 keV argon ion sputtering technique.

  18. XPS and XRF depth patina profiles of ancient silver coins

    Energy Technology Data Exchange (ETDEWEB)

    Caridi, F., E-mail: fcaridi@unime.it [Facoltà di Scienze MM. FF. NN., Università di Messina, V.le F. Stagno D’Alcontres 31, Messina (Italy); INFN-Sez. CT, Gr. coll. di Messina, V.le F. Stagno D’Alcontres 31, Messina (Italy); Torrisi, L. [Dip.to di Fisica, Università di Messina, V.le F. Stagno D’Alcontres 31, Messina (Italy); INFN-Laboratori Nazionali del Sud, V. S. Sofia 62, 95123 Catania (Italy); Cutroneo, M. [Dip.to di Fisica, Università di Messina, V.le F. Stagno D’Alcontres 31, Messina (Italy); Barreca, F. [Advanced and Nanomaterials Research S.r.l., V.le F. Stagno D’Alcontres 31, Messina (Italy); Gentile, C. [Dip.to di Fisica, Università di Messina, V.le F. Stagno D’Alcontres 31, Messina (Italy); Serafino, T. [Dip.to di Fisica della materia e ingegneria elettronica, V.le F. Stagno D’Alcontres 31, Messina (Italy); Castrizio, D. [Dip.to di Scienze dell’Antichità, Università di Messina (Italy)

    2013-05-01

    Ancient silver coins of different historical periods going from IV cent. B.C. up to recent XIX century, coming from different Mediterranean countries have been investigated with different surface physical analyses. X-ray photoelectron spectroscopy (XPS) analysis has been performed by using electron emission induced by 1.4 keV X-rays. X-ray fluorescence (XRF) analysis has been devoted by using 30 keV electron beam. Scanning electron microscopy (SEM) has been employed to analyze the surface morphology and the X-ray map distribution by using a 30 keV microbeam. Techniques were used to investigate about the patina composition and trace elements as a function of the sample depth obtained coupling XPS to 3 keV argon ion sputtering technique.

  19. Silver behenate and silver stearate powders for calibration of SAS instruments

    International Nuclear Information System (INIS)

    The possibilities of calibrations by silver behenate [CH3(CH2)20COOAg] and silver stearate [CH3 (CH2)16CO2Ag] for the small angle scattering (SAS) technique are considered. It was shown that the long-period spacing of the silver compounds allow us to check the parameters of time-of-flight (TOF) method. Results of the data obtained from small angle neutron scattering (SANS) measurements performed with the silver behenate and the silver stearate powders are presented and compared with small angle X-ray scattering (SAXS) measurements.

  20. Synthesis and antimicrobial effects of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    S kheybari

    2010-09-01

    Full Text Available "n  "n "nBackground and the purpose of the study:The most prominent nanoparticles for medical uses are nanosilver particles which are famous for their high anti-microbial activity. Silver ion has been known as a metal ion that exhibit anti-mold, anti-microbial and anti-algal properties for a long time. In particular, it is widely used as silver nitrate aqueous solution which has disinfecting and sterilizing actions. The purpose of this study was to evaluate the antimicrobial activity as well as physical properties of the silver nanoparticles prepared by chemical reduction method. "nMethods:Silver nanoparticles (NPs were prepared by reduction of silver nitrate in the presence of a reducing agent and also poly [N-vinylpyrolidone] (PVP as a stabilizer. Two kinds of NPs were synthesized by ethylene glycol (EG and glucose as reducing agent. The nanostructure and particle size of silver NPs were confirmed by scanning electron microscopy (SEM and laser particle analyzer (LPA. The formations of the silver NPs were monitored using ultraviolet-visible spectroscopy. The anti-bacterial activity of silver NPs were assessed by determination of their minimum inhibitory concentrations (MIC against the Gram positive (Staphylococcus aureus and Staphylococcus epidermidis as well as Gram-negative (Escherichia coli and Pseudomonas aeruginosa bacteria. "nResults and Conclusion:The silver nanoparticles were spherical with particle size between 10 to 250 nm. Analysis of the theoretical (Mie light scattering theory and experimental results showed that the silver NPs in colloidal solution had a diameter of approximately 50 nm. "nBoth colloidal silver NPs showed high anti-bacterial activity against Gram positive and Gram negative bacteria. Glucose nanosilver colloids showed a shorter killing time against most of the tested bacteria which could be due to their nanostructures and uniform size distribution patterns.

  1. Analysis of ancient Indian silver punch-marked coins by external PIXE

    Energy Technology Data Exchange (ETDEWEB)

    Rautray, Tapash R., E-mail: tapash.rautray@gmail.com [Department of Dental Biomaterials, School of Dentistry, Kyungpook National University, Daegu (Korea, Republic of); Institute of Physics, Bhubaneswar 751005, Orissa (India); Nayak, Suman S. [Department of Computer Science, College of Engineering, University of Illinois at Urbana Champaign, 201 North Goodwin Avenue, Urbana, IL 61801-2302 (United States); Tripathy, Bipin B. [Department of Physics, Silicon Institute of Technology, Patia, Bhubaneswar 751024 (India); Das, Saubhagyalaxmi [Institute of Physics, Bhubaneswar 751005, Orissa (India); Das, Manas R. [Department of Civil Engineering, Institute of Technical education and Research, SOA University, Jagmohan Nagar, Bhubaneswar 751030 (India); Das, Satya R. [Department of Computer Science, Institute of Technical education and Research, SOA University, Jagmohan Nagar, Bhubaneswar 751030 (India); Chattopadhyay, Pranab K. [Centre for Archaeological Studies and Training, Eastern India, 4 Camac Street (1st Floor), Kolkata 700016 (India)

    2011-10-15

    Seven silver punch-marked coins were analysed using external particle induced X-ray emission technique. The main group of elements like Ag, Cu, Au, Pb and Fe were estimated along with a number of trace/minor elements such as K, Ca, Ti, V, Cr, Mn, Co, Ni and Rb in the analysed silver coins. Gold was found in all the coins and varied between 0.7% and 6.2% indicating the better economic condition of that civilisation. - Highlights: > The silver punch-marked coins, in the current study, were in use in India between 6th century BC to 6th century AD and have been analysed by in-air PIXE. > These sets of coins have immense archaeological importance because of their very rare availability. > These coins are distinguished from other coins because of the presence of gold as major element. > While the British period coins were fabricated using modern technologies, the punch-marked coins were shaped manually with developed metal technology. > The analysis of punch-marked coins using external PIXE beam has been done for the first time, which is unique of its kind.

  2. Distribution of silver in rats following 28 days of repeated oral exposure to silver nanoparticles or silver acetate

    Directory of Open Access Journals (Sweden)

    Mortensen Alicja

    2011-06-01

    Full Text Available Abstract Background The study investigated the distribution of silver after 28 days repeated oral administration of silver nanoparticles (AgNPs and silver acetate (AgAc to rats. Oral administration is a relevant route of exposure because of the use of silver nanoparticles in products related to food and food contact materials. Results AgNPs were synthesized with a size distribution of 14 ± 4 nm in diameter (90% of the nanoparticle volume and stabilized in aqueous suspension by the polymer polyvinylpyrrolidone (PVP. The AgNPs remained stable throughout the duration of the 28-day oral toxicity study in rats. The organ distribution pattern of silver following administration of AgNPs and AgAc was similar. However the absolute silver concentrations in tissues were lower following oral exposure to AgNPs. This was in agreement with an indication of a higher fecal excretion following administration of AgNPs. Besides the intestinal system, the largest silver concentrations were detected in the liver and kidneys. Silver was also found in the lungs and brain. Autometallographic (AMG staining revealed a similar cellular localization of silver in ileum, liver, and kidney tissue in rats exposed to AgNPs or AgAc. Using transmission electron microscopy (TEM, nanosized granules were detected in the ileum of animals exposed to AgNPs or AgAc and were mainly located in the basal lamina of the ileal epithelium and in lysosomes of macrophages within the lamina propria. Using energy dispersive x-ray spectroscopy it was shown that the granules in lysosomes consisted of silver, selenium, and sulfur for both AgNP and AgAc exposed rats. The diameter of the deposited granules was in the same size range as that of the administered AgNPs. No silver granules were detected by TEM in the liver. Conclusions The results of the present study demonstrate that the organ distribution of silver was similar when AgNPs or AgAc were administered orally to rats. The presence of silver

  3. Toxicity of various silver nanoparticles compared to silver ions in Daphnia magna

    Directory of Open Access Journals (Sweden)

    Asghari Saba

    2012-04-01

    Full Text Available Abstract Background To better understand the potential ecotoxicological impacts of silver nanoparticles released into freshwater environments, the Daphnia magna 48-hour immobilization test was used. Methods The toxicities of silver nitrate, two types of colloidal silver nanoparticles, and a suspension of silver nanoparticles were assessed and compared using standard OECD guidelines. Also, the swimming behavior and visible uptake of the nanoparticles by Daphnia were investigated and compared. The particle suspension and colloids used in the toxicity tests were well-characterized. Results The results obtained from the exposure studies showed that the toxicity of all the silver species tested was dose and composition dependent. Plus, the silver nanoparticle powders subsequently suspended in the exposure water were much less toxic than the previously prepared silver nanoparticle colloids, whereas the colloidal silver nanoparticles and AgNO3 were almost similar in terms of mortality. The silver nanoparticles were ingested by the Daphnia and accumulated under the carapace, on the external body surface, and connected to the appendages. All the silver species in this study caused abnormal swimming by the D. magna. Conclusion According to the present results, silver nanoparticles should be classified according to GHS (Globally Harmonized System of classification and labeling of chemicals as "category acute 1" to Daphnia neonates, suggesting that the release of nanosilver into the environment should be carefully considered.

  4. Room temperature synthesis of silver nanowires from tabular silver bromide crystals in the presence of gelatin

    International Nuclear Information System (INIS)

    Long silver nanowires were synthesized at room temperature by a simple and fast process derived from the development of photographic films. A film consisting of an emulsion of tabular silver bromide grains in gelatin was treated with a photographic developer (4-(methylamino)phenol sulfate (metol), citric acid) in the presence of additional aqueous silver nitrate. The silver nanowires have lengths of more than 50 μm, some even more than 100 μm, and average diameters of about 80 nm. Approximately, 70% of the metallic silver formed in the reduction consists of silver nanowires. Selected area electron diffraction (SAED) results indicate that the silver nanowires grow along the [111] direction. It was found that the presence of gelatin, tabular silver bromide crystals and silver ions in solution are essential for the formation of the silver nanowires. The nanowires appear to originate from the edges of the silver bromide crystals. They were characterized by transmission electron microscopy (TEM), SAED, scanning electron microscopy (SEM), and powder X-ray diffraction (XRD)

  5. Glass frits coated with silver nanoparticles for silicon solar cells

    Science.gov (United States)

    Li, Yingfen; Gan, Weiping; Zhou, Jian; Li, Biyuan

    2015-06-01

    Glass frits coated with silver nanoparticles were prepared by electroless plating. Gum Arabic (GA) was used as the activating agent of glass frits without the assistance of stannous chloride or palladium chloride. The silver-coated glass frits prepared with different GA dosages were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The characterization results indicated that silver-coated glass frits had the structures of both glass and silver. Spherical silver nanoparticles were distributed on the glass frits evenly. The density and particle size of silver nanoparticles on the glass frits can be controlled by adjusting the GA dosage. The silver-coated glass frits were applied to silver pastes to act as both the densification promoter and silver crystallite formation aid in the silver electrodes. The prepared silver-coated glass frits can improve the photovoltaic performances of solar cells.

  6. Economic impact study of the Uranium Mill Tailings Remedial Action Project in Colorado: Colorado state fiscal year 1993

    International Nuclear Information System (INIS)

    The Colorado economic impact study summarizes employment and economic benefits to the state from activities associated with the Uranium Mill Tailings Remedial Action (UMTRA) Project during Colorado state fiscal year 1993 (July 1, 1992, through June 30, 1993). To capture employment benefits, a questionnaire was distributed to subcontractor employees at the active UMTRA Project sites of Grand Junction, Rifle, and Gunnison, Colorado. An estimated 52 percent of the employees working on the UMTRA Project responded to this information request. Economic data were requested from each site prime subcontractor, as well as from the Remedial Action Contractor. The most significant benefits associated with the UMTRA Project in Colorado are summarized

  7. Economic impact study of the Uranium Mill Tailings Remedial Action project in Colorado: Colorado state fiscal year 1995

    International Nuclear Information System (INIS)

    This Colorado economic impact study summarizes employment and economic benefits to the state from activities associated with the Uranium Mill Tailings Remedial Action (UMTRA) Project during Colorado state fiscal year (FY) 1995 (1 July 1994 through 30 June 1995). To capture employment information, a questionnaire was distributed to subcontractor employees at the active UMTRA Project sites of Grand Junction, Gunnison, Maybell, Naturita, Rifle, and Slick Rock, Colorado. Economic data were requested from the Remedial Action Contractor (RAC), the Technical Assistance Contractor (TAC) and the US Department of Energy (DOE). The most significant benefits associated with the UMTRA Project in Colorado are summarized

  8. Development of nanostructured silver vanadates decorated with silver nanoparticles as a novel antibacterial agent

    Science.gov (United States)

    Holtz, R. D.; Souza Filho, A. G.; Brocchi, M.; Martins, D.; Durán, N.; Alves, O. L.

    2010-05-01

    In this work we report the synthesis, characterization and application of silver vanadate nanowires decorated with silver nanoparticles as a novel antibacterial agent. These hybrid materials were synthesized by a precipitation reaction of ammonium vanadate and silver nitrate followed by hydrothermal treatment. The silver vanadate nanowires have lengths of the order of microns and diameters around 60 nm. The silver nanoparticles decorating the nanowires present a diameter distribution varying from 1 to 20 nm. The influence of the pH of the reaction medium on the chemical structure and morphology of silver vanadates was studied and we found that synthesis performed at pH 5.5-6.0 led to silver vanadate nanowires with a higher morphological yield. The antimicrobial activity of these materials was evaluated against three strains of Staphylococcus aureus and very promising results were found. The minimum growth inhibiting concentration value against a MRSA strain was found to be ten folds lower than for the antibiotic oxacillin.

  9. Reaction Diffusion in the Silver-Zinc and Silver-Aluminum Systems

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Japnell D.; Powell, Gordon W.

    1971-10-01

    Multiphase diffusion was investigated in the silver-zinc and silver-aluminum binary systems using metallographic and electron microprobe techniques. Diffusion couples in the silver-zinc system were prepared by electroplating silver onto coupons of a AgZn alloy (62.2% Ag), and diffusion behavior was studied at 600 and 650 degrees C. Couples in the silver-aluminum system were prepared by electroplating silver onto coupons of a AgAl alloy (87.7% Ag) and diffusion measurements were made between 400-600 degrees C. Significant deviations from equilibrium compositions were observed at the moving interphase boundary in each couple. The nucleation of a non-equilibrium silver-rich phase was observed at the location of the initial interface in many of the couples.

  10. Development of nanostructured silver vanadates decorated with silver nanoparticles as a novel antibacterial agent

    Energy Technology Data Exchange (ETDEWEB)

    Holtz, R D; Souza Filho, A G; Alves, O L [Laboratorio de Quimica do Estado Solido (LQES), Instituto de Quimica, Universidade Estadual de Campinas, CP 6154, 13081-970, Campinas-SP (Brazil); Brocchi, M; Martins, D [Departamento de Genetica, Evolucao and Bioagentes, Instituto de Biologia, Universidade Estadual de Campinas, Campinas-SP (Brazil); Duran, N, E-mail: rholtz@iqm.unicamp.br, E-mail: agsf@fisica.ufc.br, E-mail: oalves@iqm.unicamp.br [Laboratorio de Quimica Biologica, Instituto de Quimica, Universidade Estadual de Campinas, Campinas-SP (Brazil)

    2010-05-07

    In this work we report the synthesis, characterization and application of silver vanadate nanowires decorated with silver nanoparticles as a novel antibacterial agent. These hybrid materials were synthesized by a precipitation reaction of ammonium vanadate and silver nitrate followed by hydrothermal treatment. The silver vanadate nanowires have lengths of the order of microns and diameters around 60 nm. The silver nanoparticles decorating the nanowires present a diameter distribution varying from 1 to 20 nm. The influence of the pH of the reaction medium on the chemical structure and morphology of silver vanadates was studied and we found that synthesis performed at pH 5.5-6.0 led to silver vanadate nanowires with a higher morphological yield. The antimicrobial activity of these materials was evaluated against three strains of Staphylococcus aureus and very promising results were found. The minimum growth inhibiting concentration value against a MRSA strain was found to be ten folds lower than for the antibiotic oxacillin.

  11. Development of nanostructured silver vanadates decorated with silver nanoparticles as a novel antibacterial agent

    International Nuclear Information System (INIS)

    In this work we report the synthesis, characterization and application of silver vanadate nanowires decorated with silver nanoparticles as a novel antibacterial agent. These hybrid materials were synthesized by a precipitation reaction of ammonium vanadate and silver nitrate followed by hydrothermal treatment. The silver vanadate nanowires have lengths of the order of microns and diameters around 60 nm. The silver nanoparticles decorating the nanowires present a diameter distribution varying from 1 to 20 nm. The influence of the pH of the reaction medium on the chemical structure and morphology of silver vanadates was studied and we found that synthesis performed at pH 5.5-6.0 led to silver vanadate nanowires with a higher morphological yield. The antimicrobial activity of these materials was evaluated against three strains of Staphylococcus aureus and very promising results were found. The minimum growth inhibiting concentration value against a MRSA strain was found to be ten folds lower than for the antibiotic oxacillin.

  12. Human lead exposure in a late 19th century mental asylum population

    International Nuclear Information System (INIS)

    Lead isotope ratios and lead (Pb) levels were analyzed in 33 individuals from a forgotten cemetery at the Colorado Mental Health Institute at Pueblo, Colorado dating to 1879-1899. Isotopic ratios from healing bone fractures, cortical bone, and tooth dentine provide information about sources of Pb exposures over a range of time that illuminates individual's life histories and migration patterns. Historical records and Pb production data from the 19th century were used to create a database for interpreting Pb exposures for these African, Hispanic and European Americans. The analysis of these individuals suggests that Pb exposure noticeably impacted the mental health of 5-10% of the asylum patients in this frontier population, a high number by standards today, and that differences exist in the three ancestral groups' exposure histories

  13. Human lead exposure in a late 19th century mental asylum population.

    Science.gov (United States)

    Bower, Nathan W; McCants, Sarah A; Custodio, Joseph M; Ketterer, Michael E; Getty, Stephen R; Hoffman, J Michael

    2007-01-01

    Lead isotope ratios and lead (Pb) levels were analyzed in 33 individuals from a forgotten cemetery at the Colorado Mental Health Institute at Pueblo, Colorado dating to 1879-1899. Isotopic ratios from healing bone fractures, cortical bone, and tooth dentine provide information about sources of Pb exposures over a range of time that illuminates individual's life histories and migration patterns. Historical records and Pb production data from the 19th century were used to create a database for interpreting Pb exposures for these African, Hispanic and European Americans. The analysis of these individuals suggests that Pb exposure noticeably impacted the mental health of 5-10% of the asylum patients in this frontier population, a high number by standards today, and that differences exist in the three ancestral groups' exposure histories. PMID:17126382

  14. Human lead exposure in a late 19th century mental asylum population

    Energy Technology Data Exchange (ETDEWEB)

    Bower, Nathan W. [Department of Chemistry, Colorado College, Colorado Springs, CO 80903-3294 (United States)]. E-mail: nbower@coloradocollege.edu; McCants, Sarah A. [Department of Chemistry, Colorado College, Colorado Springs, CO 80903-3294 (United States); Custodio, Joseph M. [Department of Chemistry, Colorado College, Colorado Springs, CO 80903-3294 (United States); Ketterer, Michael E. [Departments of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, AZ 86011-5698 (United States); Getty, Stephen R. [Biological Sciences Curriculum Study, Colorado Springs, CO 80918 (United States); Hoffman, J. Michael [Department of Anthropology, Colorado College, Colorado Springs, CO 8090-3294 (United States)

    2007-01-01

    Lead isotope ratios and lead (Pb) levels were analyzed in 33 individuals from a forgotten cemetery at the Colorado Mental Health Institute at Pueblo, Colorado dating to 1879-1899. Isotopic ratios from healing bone fractures, cortical bone, and tooth dentine provide information about sources of Pb exposures over a range of time that illuminates individual's life histories and migration patterns. Historical records and Pb production data from the 19th century were used to create a database for interpreting Pb exposures for these African, Hispanic and European Americans. The analysis of these individuals suggests that Pb exposure noticeably impacted the mental health of 5-10% of the asylum patients in this frontier population, a high number by standards today, and that differences exist in the three ancestral groups' exposure histories.

  15. The 8th Century Megadrought Across North America

    Science.gov (United States)

    Stahle, D. W.; Therrell, M. D.; Cleaveland, M. K.; Fye, F. K.; Cook, E. R.; Grissino-Mayer, H. D.; Acuna-Soto, R.

    2002-12-01

    Tree-ring data suggest that the 8th and 16th century megadroughts may have been the most severe and sustained droughts to impact North America in the past 1500 years. The 16th century megadrought may have persisted for up to 40 years, and extended from the tropics to the boreal forest and from the Pacific to Atlantic coasts. Evidence for the 8th century drought is sparse, but tree-ring and lake sediment data indicate that this drought extended from the northern Great Plains, across the southwestern United States, and into central Mexico and the Yucatan peninsula. Tree-ring data from Colorado and New Mexico document severe drought from A.D. 735-765, and may provide accurate and precise dating for the onset of the epic droughts reconstructed during the late first millennium A.D. with sedimentary data from Elk Lake, Minnesota; Moon Lake, South Dakota; La Piscina de Yuriria, Guanajuato; and Lake Chichancanab, Yucatan. If these chronological refinements are correct, then the sedimentary records suggest much greater persistence to the 8th century megadrought than indicated by the very high resolution tree-ring data, and a strong second pulse of prolonged drought late in the first millennium. Analyses of instrumental precipitation and drought indices during the 20th century, along with tree-ring reconstructions of climate in Mexico and the Southwest, indicate that annual and decadal droughts can both simultaneously impact the entire region from New Mexico and Texas down into central Mexico. The intensity and large-scale impact of drought across this region seem to be greatest when La Nina conditions and the low phase of the North Pacific oscillation prevail. The tree-ring dated 8th century megadrought occurred near the decline of the Classic Period civilizations at Teotihuacan in central Mexico and in the Mayan region of the Yucatan. The 8th century megadrought may have interacted with anthropogenic environmental degradation, epidemic disease, and social upheaval to

  16. Archaeometrical studies on medieval silver coins at the Bucharest TANDEM Accelerator

    International Nuclear Information System (INIS)

    An extensive study on Medieval Moldavian (XIVth - XVIth Centuries) silver coins (Groschen) using 3 MeV protons PIXE (Proton Induced X-ray Emission) and '241 Am source based XRF (X-Ray Fluorescence) was performed in order to determine the evolution of the coinage (debasement, metal sources, minting technologies). XRF was used to determine heavier elements concentrations. Comparing the trace elements results (Bi, Pb, Zn, Au) obtained on these samples with the ones on coins from Hungary, Poland, Tatar Khanate, Bohemia we bring support to the curator hypothesis that a lot of Moldavian emissions were made by melting foreign coins, possibly obtained as customs taxes or from trade with these neighbouring countries. For the late medieval silver coins, the high Hg content may be an indication of an imperfect metallurgical processing of the local silver ores. The relationship between the silver content of the coins and the military conflicts corresponding to the minting periods is discussed, taking into account the fact that crisis times are characterized by a decrease in the precious metal concentration. (authors)

  17. A Roman bronze statuette with gilded silver mask from Sardinia: an EDXRF study

    Science.gov (United States)

    Cesareo, Roberto; Brunetti, Antonio; D'Oriano, Rubens; Canu, Alba; Demontis, Gonaria Mattia; Celauro, Angela

    2013-12-01

    A Roman bronze statuette from the 2nd Century BC was recovered from a nuragic sanctuary close to Florinas, in the north of Sardinia. The facial portion of the statuette is covered by a silver mask, partially gilded and attached to the bronze by tin-lead welding. The silver mask was carefully analyzed by portable energy-dispersive X-ray fluorescence (EDXRF), a non-destructive and non-invasive method. The aim of the analysis was to reconstruct the layered structure of the silver gilt mask, and to determine homogeneity and thickness of the gold, silver and lead-tin sheets. This is possible by using the internal ratio of the X-ray lines, i.e. starting from the surface, Au (L α/L β), Ag (K α/K β), Au-L α/Ag-K α and Pb (L α/L β).The results were compared with those obtained with simulated X-ray spectra, obtained both experimentally and by using the Monte Carlo simulation technique.

  18. Radiation stimulated photochromism in glasses containing silver

    International Nuclear Information System (INIS)

    New type of photochromous transformations, occuring without halogen but with preliminary radiation stimulation, are detected in silver-activated glasses. Reversible variation of γ-irradiated glass color under the effect of UV exposure is shown to be linked with electron phototransfer between Ag2+ silver molecular ion and PO42- ion radical

  19. Topical silver for preventing wound infection

    NARCIS (Netherlands)

    M.N. Storm-Versloot; C.G. Vos; D.T. Ubbink; H. Vermeulen

    2010-01-01

    BACKGROUND: Silver-containing treatments are popular and used in wound treatments to combat a broad spectrum of pathogens, but evidence of their effectiveness in preventing wound infection or promoting healing is lacking. OBJECTIVES: To establish the effects of silver-containing wound dressings and

  20. Properties of silver chloride track detectors

    International Nuclear Information System (INIS)

    The experiments on preparation of silver chloride track detectors and their properties are described. The results of X-ray structural analysis and data on sensitivity to charged particles and actinic light of silver chloride crystals, doped with several elements, are presented. (orig.)

  1. Movie Director Bags a Silver Bear

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Chinese director and film writer Wang Xiaoshuai has walked away with the Silver Bear award at the 58th Berlin International Film Festival for best script of Zuo You, or In Love We Trust. Back in 2001, Wang won his first Silver Bear award for directing Beijing

  2. 21st Century Skills Map

    Science.gov (United States)

    Partnership for 21st Century Skills, 2011

    2011-01-01

    The Partnership for 21st Century Skills (P21) has forged alliances with key national organizations representing the core academic subjects, including Social Studies, English, Math, Science, Geography, World Languages and the Arts. These collaborations have resulted in the development of 21st Century Skills Maps that illustrate the essential…

  3. A century of antenna development

    Science.gov (United States)

    Olver, A. D.

    The paper describes a century of antenna development as part of a century of radio communications. This historical review examines, chronologically, the pre-Hertz period, Hertz antennas, the microwave optics period, the Marconi era, short waves, theoretical design before and after computers, and radar. Consideration is also given to mobile antennas, microwave comunications, radio astronomy, and satellite comunications.

  4. Physiological response to acute silver exposure in the freshwater crayfish (Cambarus diogenes diogenes) - a model invertebrate?

    DEFF Research Database (Denmark)

    Grosell, Martin Hautopp; Brauner, C.J.; Kelly, S.P.; McGeer, J.C.; Bianchini, A.; Wood, C. M.

    Crayfish, Silver toxicity, Osmoregulatory disturbance, Silver accumulation, Unidirectional Na+ flux......Crayfish, Silver toxicity, Osmoregulatory disturbance, Silver accumulation, Unidirectional Na+ flux...

  5. Analytical Results for Agricultural Soils Samples from a Monitoring Program Near Deer Trail, Colorado (USA)

    Science.gov (United States)

    Crock, J.G.; Smith, D.B.; Yager, T.J.B.

    2009-01-01

    alpha and beta activity (Colorado Department of Public Health and Environment, Hazardous Materials and Waste Management Division, 1997; Colorado Department of Public Health and Environment,1998; U.S. Environmental Protection Agency, 1993). Since these were the identified priority parameters for the biosolids, the soils have the same set of priority parameters. Although the composite soils' priority analytes have been reported earlier to Metro District, the remaining elemental datasets for both the composite soils samples and selected fields' individual subsamples' data are presented here for the first time. More information about the other monitoring components is presented elsewhere in the literature (http://co.water.usgs.gov/projects/CO406/CO406.html). In general, the objective of each component of the study was to determine whether concentrations of priority parameters (1) were higher than regulatory limits, (2) were increasing with time, and(or) (3) were significantly higher in biosolids-applied areas than in a similar farmed area where biosolids were not applied. The method chosen for sampling the soils proved to be an efficient and reliable representation of the average composition of each field. This was shown by analyzing individual subsamples, averaging the resulting values, and then comparing the values to the composited samples' values. The soil chemistry shows distinct differences between the two sites, most likely due to the different underlying parent material. Biosolids data were used to compile an inorganic-chemical biosolids signature that can be contrasted with the geochemical signature of the agricultural soils for this site. The biosolids signature and an understanding of the geology and hydrology of the site can be used to separate biosolids effects from natural geochemical effects. Elements of particular interest for a biosolids signature after application in the soils include bismuth, copper, silver, mercury, and phosphorus. This signat

  6. Colorado Fathers' Resource Guide = Guia de Recursos para los Padres en Colorado.

    Science.gov (United States)

    Colorado Foundation for Families and Children, Denver.

    Developed through the Colorado Fatherhood Connection, this guide, in English- and Spanish-language versions, provides suggestions and resources for fathers as well as tips on discipline, communication, and activities fathers can do with their children. Topics addressed in the guide include characteristics of responsible fatherhood, characteristics…

  7. One-Pot Silver Nanoring Synthesis

    Directory of Open Access Journals (Sweden)

    Drogat Nicolas

    2009-01-01

    Full Text Available Abstract Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH4 in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV–vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings depended on AgNO3/NaBH4 ratio, pH and reaction temperature. Particles were analysed by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. A reaction pathway is proposed to explain silver nanoring formation.

  8. Fluorescent silver nanoparticles via exploding wire technique

    Indian Academy of Sciences (India)

    Alqudami Abdullah; S Annapoorni

    2005-11-01

    Aqueous solution containing spherical silver nanoparticles of 20–80 nm size have been generated using a newly developed novel electro-exploding wire (EEW) technique where thin silver wires have been exploded in double distilled water. Structural properties of the resulted nanoparticles have been studied by means of X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The absorption spectrum of the aqueous solution of silver nanoparticles showed the appearance of a broad surface plasmon resonance (SPR) peak centered at a wavelength of 390 nm. The theoretically generated SPR peak seems to be in good agreement with the experimental one. Strong green fluorescence emission was observed from the water-suspended silver nanoparticles excited with light of wavelengths 340, 360 and 390 nm. The fluorescence of silver nanoparticles could be due to the excitation of the surface plasmon coherent electronic motion with the small size effect and the surface effect considerations.

  9. Effect of silver nitrate concentration of silver nanowires synthesized using a polyol method and their application as transparent conductive films

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jian-Yang [Department of Electronic Engineering, National Yunlin University of Science and Technology, Yunlin 640, Taiwan (China); Hsueh, Yu-Lee [Graduate School of Engineering Science and Technology, National Yunlin University of Science and Technology, Yunlin 640, Taiwan (China); Huang, Jung-Jie, E-mail: jjhuang@mail.dyu.edu.tw [Department of Industrial Engineering and Management, DaYeh University, Changhua 51591, Taiwan (China); Wu, Jia-Rung [Department of Computer Science and Information Engineering, Asia University, Taichung 413, Taiwan (China)

    2015-06-01

    Silver nanowires were synthesized using a polyol process by employing ethylene glycol, poly(N-vinylpyrrolidone), and silver nitrate as precursors. The concentration of silver nitrate was varied to study the resulting changes in aspect ratios of silver nanowires. The experimental results indicated that the growth characteristics of silver nanowires were affected by the synthesis temperature, the concentration of silver nitrate, and the rate at which silver nitrate was added. Field-emission scanning electron microscopy, UV–visible spectrophotometry, and X-ray diffractometry were employed to characterize the silver nanowires. As the concentration of silver nitrate was reduced, the diameters of the silver nanowires decreased, increasing the aspect ratio. The optimal diameter and length of the silver nanowires were 100 nm and 20 μm, respectively. A thin film composed of silver nanowires exhibited average transmittance of 92.15% at visible wavelengths and a sheet resistance of 20 Ω/sq; such a film could be used as a transparent conductive film in commercial applications. - Highlights: • Using a polyol method to synthesize of silver nanowire • Concentration effect of silver nitrate on the synthesis was discussed. • Seed precursors are not used during the silver nanowire synthesizing. • The silver nanowire diameter and length were 100 nm and 20 μm, respectively. • High transmittance and low sheet resistance of silver nanowire film can be obtained.

  10. Effect of silver nitrate concentration of silver nanowires synthesized using a polyol method and their application as transparent conductive films

    International Nuclear Information System (INIS)

    Silver nanowires were synthesized using a polyol process by employing ethylene glycol, poly(N-vinylpyrrolidone), and silver nitrate as precursors. The concentration of silver nitrate was varied to study the resulting changes in aspect ratios of silver nanowires. The experimental results indicated that the growth characteristics of silver nanowires were affected by the synthesis temperature, the concentration of silver nitrate, and the rate at which silver nitrate was added. Field-emission scanning electron microscopy, UV–visible spectrophotometry, and X-ray diffractometry were employed to characterize the silver nanowires. As the concentration of silver nitrate was reduced, the diameters of the silver nanowires decreased, increasing the aspect ratio. The optimal diameter and length of the silver nanowires were 100 nm and 20 μm, respectively. A thin film composed of silver nanowires exhibited average transmittance of 92.15% at visible wavelengths and a sheet resistance of 20 Ω/sq; such a film could be used as a transparent conductive film in commercial applications. - Highlights: • Using a polyol method to synthesize of silver nanowire • Concentration effect of silver nitrate on the synthesis was discussed. • Seed precursors are not used during the silver nanowire synthesizing. • The silver nanowire diameter and length were 100 nm and 20 μm, respectively. • High transmittance and low sheet resistance of silver nanowire film can be obtained

  11. Corrosion processes of triangular silver nanoparticles compared to bulk silver

    Energy Technology Data Exchange (ETDEWEB)

    Keast, V. J., E-mail: vicki.keast@newcastle.edu.au; Myles, T. A. [University of Newcastle, School of Mathematical and Physical Sciences (Australia); Shahcheraghi, N.; Cortie, M. B. [University of Technology Sydney, Institute for Nanoscale Technology (Australia)

    2016-02-15

    Excessive corrosion of silver nanoparticles is a significant impediment to their use in a variety of potential applications in the biosensing, plasmonic and antimicrobial fields. Here we examine the environmental degradation of triangular silver nanoparticles (AgNP) in laboratory air. In the early stages of corrosion, transmission electron microscopy shows that dissolution of the single-crystal, triangular, AgNP (side lengths 50–120 nm) is observed with the accompanying formation of smaller, polycrystalline Ag particles nearby. The new particles are then observed to corrode to Ag{sub 2}S and after 21 days nearly full corrosion has occurred, but some with minor Ag inclusions remaining. In contrast, a bulk Ag sheet, studied in cross section, showed an adherent corrosion layer of only around 20–50 nm in thickness after over a decade of being exposed to ambient air. The results have implications for antibacterial properties and ecotoxicology of AgNP during corrosion as the dissolution and reformation of Ag particles during corrosion will likely be accompanied by the release of Ag{sup +} ions.

  12. Corrosion processes of triangular silver nanoparticles compared to bulk silver

    International Nuclear Information System (INIS)

    Excessive corrosion of silver nanoparticles is a significant impediment to their use in a variety of potential applications in the biosensing, plasmonic and antimicrobial fields. Here we examine the environmental degradation of triangular silver nanoparticles (AgNP) in laboratory air. In the early stages of corrosion, transmission electron microscopy shows that dissolution of the single-crystal, triangular, AgNP (side lengths 50–120 nm) is observed with the accompanying formation of smaller, polycrystalline Ag particles nearby. The new particles are then observed to corrode to Ag2S and after 21 days nearly full corrosion has occurred, but some with minor Ag inclusions remaining. In contrast, a bulk Ag sheet, studied in cross section, showed an adherent corrosion layer of only around 20–50 nm in thickness after over a decade of being exposed to ambient air. The results have implications for antibacterial properties and ecotoxicology of AgNP during corrosion as the dissolution and reformation of Ag particles during corrosion will likely be accompanied by the release of Ag+ ions

  13. Ferroelectricity in Silver Perovskite Oxides

    OpenAIRE

    Fu, Desheng; Itoh, Mitsuru

    2011-01-01

    There are two silver perovskite oxides: AgNbO3 and AgTaO3. AgNbO3 has a noncentrosymmetric group of Pmc21 at room temperature with a ferri-electric ordering of polarization. Such a ferri-electric state with small polarization can be changed into a ferroelectric state with very large polarization by a high electric field or by a chemical modification. The induced ferroelectric phase shows promising electromechanical response for applications in piezoelectric devices. In contrast, AgTaO3 is a q...

  14. Plasma Catalytic Synthesis of Silver Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu-Tao; GUO Ying; MA Teng-Cai

    2011-01-01

    We present the experimental results of plasma catalytic synthesis of colloidal silver nanoparticles, using AgNO3 as the precursor, ethanol as the solvent and reducing agent, and poly vinyl pyrrolidone (PVP) as the macromolecular surfactant. The plasma is generated by an atmospheric argon dielectric barrier discharge jet. Silver nanoparticles are produced instantly once the plasma is ignited. The system is not heated so it is necessary to use traditional chemical methods. The samples are characterized by UV-visible absorbance and transmission electron microscopy. For glow discharge mode no obvious silver nanoparticles are observed. For low voltage filamentary streamer discharge mode a lot of silver nanoparticles with the mean diameter of ~3.5nm are generated and a further increase of the voltage causes the occurrence of agglomeration.%We present the experimental results of plasma catalytic synthesis of colloidal silver nanoparticles,using AgNO3 as the precursor,ethanol as the solvent and reducing agent,and poly vinyl pyrrolidone (PVP) as the macromolecular surfactant.The plasma is generated by an atmospheric argon dielectric barrier discharge jet.Silver nanoparticles are produced instantly once the plasma is ignited.The system is not heated so it is necessary to use traditional chemical methods.The samples are characterized by UV-visible absorbance and transmission electron microscopy.For glow discharge mode no obvious silver nanoparticles are observed.For low voltage filamentary streamer discharge mode a lot of silver nanoparticles with the mean diameter of ~3.5nm are generated and a further increase of the voltage causes the occurrence of agglomeration.The study of silver nanoparticles has been an extremely active area in recent years because of their important physical and chemical properties as a catalyst and antimicrobial reagent,for example.A number of methods for silver nanoparticle preparation have been developed,[1-3] among them chemical reduction is

  15. Evaluation of a silver-ion based purification system for rainwater harvesting at a small-scale community level

    OpenAIRE

    Adler, I; Hudson-Edwards, K.A.; Campos, L C

    2013-01-01

    Silver has been known for centuries to be a powerful disinfectant, with no known harmful effects to humans if applied in adequate doses. Although its use was partially discontinued with the advent of chlorination and modern antibiotics, the discovery of bacterial resistance and disinfection by-products has enabled its re-emergence as a viable water purification option. On the other hand, implementation in small-scale rainwater harvesting (RWH) systems has received little attention, possibly d...

  16. Cancer incidence study in Mesa County, Colorado

    International Nuclear Information System (INIS)

    In November of 1982 the Colorado Department of Health completed an epidemiologic investigation of leukemia, multiple myeloma, and cancers of the lung, stomach, pancreas and colon in Mesa County, Colorado for the years 1970 to 1979. This investigation was performed in response to a concern that the presence of uranium mill tailings in some Mesa County homes presents a potential cancer hazard. The results of the investigation show that the incidence of multiple myeloma, colon, stomach and pancreatic cancer are not above expected rates. The incidence of leukemia is not above expected rates for the entire study period, 1970 to 1979. The incidence of lung cancer appears elevated when compared to the The Third National Cancer Survey data for Colorado but lower than expected when compared to Surveillance, Epidemiology and End Results data. To further examine the leukemia and lung cancer incidence findings, a case/control study was conducted. The controls consisted of colon, stomach and pancreatic cancer cases. The results of the leukemia case/control analysis show no association with the radiation exposure variables: occupational radiation exposure; uranium mining exposure; having ever lived in a type A home (uranium tailings home); and radiation therapy. The lung cancer case/control analysis shows a significant association with only the radiation exposure variable, uranium mining history, indicating cases were more likely to have been uranium miners than were controls. As with leukemia, the study found no association between lung cancer and living in a uranium mill tailings home. The relatively low radiation exposures typical of type A homes and the small number of persons exposed make it very difficult to establish, by epidemiologic methods, that a risk exists

  17. Development of industrial minerals in Colorado

    Science.gov (United States)

    Arbogast, Belinda F.; Knepper, Daniel H.; Langer, William H.; Cappa, James A.; Keller, John W.; Widmann, Beth L.; Ellefsen, Karl J.; Klein, Terry L.; Lucius, Jeffrey E.; Dersch, John S.

    2011-01-01

    Technology and engineering have helped make mining safer and cleaner for both humans and the environment. Inevitably, mineral development entails costs as well as benefits. Developing a mine is an environmental, engineering, and planning challenge that must conform to many Federal, State, and local regulations. Community collaboration, creative design, and best management practices of sustainability and biodiversity can be positive indicators for the mining industry. A better understanding of aesthetics, culture, economics, geology, climate, vegetation and wildlife, topography, historical significance, and regional land planning is important in resolving land-use issues and managing mineral resources wisely. Ultimately, the consuming public makes choices about product use (including water, food, highways, housing, and thousands of other items) that influence operations of the mineral industry. Land planners, resource managers, earth scientists, designers, and public groups have a responsibility to consider sound scientific information, society's needs, and community appeals in making smart decisions concerning resource use and how complex landscapes should change. An effort to provide comprehensive geosciences data for land management agencies in central Colorado was undertaken in 2003 by scientists of the U.S. Geological Survey and the Colorado Geological Survey. This effort, the Central Colorado Assessment Project, addressed a variety of land-use issues: an understanding of the availability of industrial and metallic rocks and minerals, the geochemical and environmental effects of historic mining activity on surface water and groundwater, and the geologic controls on the availability and quality of groundwater. The USDA Forest Service and other land management agencies have the opportunity to contribute to the sustainable management of natural aggregate and other mineral resources through the identification and selective development of mineral resources and the

  18. 77 FR 15093 - Public Service Company of Colorado;

    Science.gov (United States)

    2012-03-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Public Service Company of Colorado; Notice of Application Tendered for... Public Service Company of Colorado. e. Name of Project: Cabin Creek Pumped Storage Project. f....

  19. Extensive Green Roof Research Program at Colorado State University

    Science.gov (United States)

    In the high elevation, semi-arid climate of Colorado, green roofs have not been scientifically tested. This research examined alternative plant species, media blends, and plant interactions on an existing modular extensive green roof in Denver, Colorado. Six plant species were ev...

  20. 77 FR 21803 - Notice of Competitive Coal Lease Sale, Colorado

    Science.gov (United States)

    2012-04-11

    ... Bureau of Land Management Notice of Competitive Coal Lease Sale, Colorado AGENCY: Bureau of Land... Creek East Tract described below in Gunnison County, Colorado, will be offered for competitive lease by... lease sale will be held at 10 a.m., May 15, 2012. The sealed bid must be submitted on or before 10...

  1. Morphosynthesis of cubic silver cages on monolithic activated carbon.

    Science.gov (United States)

    Wang, Fei; Zhao, Hong; Lai, Yijian; Liu, Siyu; Zhao, Binyuan; Ning, Yuesheng; Hu, Xiaobin

    2013-11-14

    Cubic silver cages were prepared on monolithic activated carbon (MAC) pre-absorbed with Cl(-), SO4(2-), or PO4(3-) anions. Silver insoluble salts served as templates for the morphosynthesis of silver cages. The silver ions were reduced by reductive functional groups on MAC micropores through a galvanic cell reaction mechanism. PMID:24080952

  2. Suitsetamisega võitlemisel ei aita inimeste kiusamine / Silver Meikar

    Index Scriptorium Estoniae

    Meikar, Silver, 1978-

    2004-01-01

    Suitsetamise vastu võitlemisel ei tohiks kasutada rangelt seadusi vaid võimaldada soodsalt osta suitsetamisvastaseid vahendeid, leiab autor. Vt. ka: Silver Meikar: Olen valmis hoidma Eesti edu; Silver Meikar saatis lugejakirja Saksamaa päevalehtedele; Arvamusi Silver Meikarist; Silver Meikar loobus paberkandjale trükitud seaduseelnõudest

  3. Electrospun polyacrylonitrile nanofibers loaded with silver nanoparticles by silver mirror reaction

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yongzheng; Li, Yajing; Zhang, Jianfeng; Yu, Zhongzhen; Yang, Dongzhi, E-mail: yangdz@mail.buct.edu.cn

    2015-06-01

    The silver mirror reaction (SMR) method was selected in this paper to modify electrospun polyacrylonitrile (PAN) nanofibers, and these nanofibers loaded with silver nanoparticles showed excellent antibacterial properties. PAN nanofibers were first pretreated in AgNO{sub 3} aqueous solution before the SMR process so that the silver nanoparticles were distributed evenly on the outer surface of the nanofibers. The final PAN nanofibers were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), TEM-selected area electron diffraction (SAED), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). SEM, TEM micrographs and SAED patterns confirmed homogeneous dispersion of the silver nanoparticles which were composed of monocrystals with diameters 20–30 nm. EDS and XRD results showed that these monocrystals tended to form face-centered cubic single silver. TGA test indicated that the nanoparticles loaded on the nanofibers reached above 50 wt.%. This material was also evaluated by the viable cell-counting method. The results indicated that PAN nanofibers loaded with silver nanoparticles exhibited excellent antimicrobial activities against gram-negative Escherichia coli (E. coli), gram-positive Staphylococcus aureus (S. aureus) and the fungus Monilia albicans. Thus, this material had many potential applications in biomedical fields. - Highlights: • Silver mirror reaction was used to prepare nanofibers loaded with silver nanoparticles. • The SAED patterns demonstrated the monocrystallinity of silver nanocrystals. • The XRD results showed nanoparticles tended to be face-centered cubic single silver. • The material showed excellent antimicrobial activities against bacteria and fungi.

  4. Antimicrobial effects of silver zeolite,silver zirconium phosphate silicate and silver zirconium phosphate against oral microorganisms

    Institute of Scientific and Technical Information of China (English)

    Sirikamon; Saengmee-anupharb; Toemsak; Srikhirin; Boonyanit; Thaweboon; Sroisiri; Thaweboon; Taweechai; Amornsakchai; Surachai; Dechkunakorn; Theeralaksna; Suddhasthira

    2013-01-01

    Objective:To evaluate the antimicrobial activities of silver inorganic materials,including silver zeolite(AgZ),silver zirconium phosphate silicate(AgZrPSi)and silver zirconium phosphate(AgZrp),against oral microorganisms.In line with this objective,the morphology and structure of each type of silver based powders were also investigated.Methods:The antimicrobial activities of AgZ,AgZrPSi and AgZrP were tested against Streptococcus mutans,Lactobacillus casei,Candida albicans and Staphylococcus aureus using disk diffusion assay as a screening test.The minimum inhibitory concentration(MIC)and minimum lethal concentration(MLC)were determined using the modified membrane method.Scanning electron microscope and X-ray diffraction were used to investigate the morphology and structure of these silver materials.Results:All forms of silver inorganic materials could inhibit the growth of all test microorganisms.The MIC of AgZ,AgZrPSi and AgZrP was 10.0 g/L whereas MLC ranged between 10.0-60.0 g/L.In terms of morphology and structure.AgZrPSi and AgZrP had smaller sized particles(1.5-3.0μm)and more uniformly shaped than AgZ.Conclusions:Silver inorganic materials in the form of AgZ,AgZrPSi and AgZrP had antimicrobial effects against all test oral microorganisms and those activities may be influenced by the crystal structure of carriers.These results suggest that these silver materials may be useful metals applied to oral hygiene products to provide antimicrobial activity against oral infection.

  5. Characterization of the silver coins of the Hoard of Beçin by X-ray based methods

    Science.gov (United States)

    Rodrigues, M.; Schreiner, M.; Melcher, M.; Guerra, M.; Salomon, J.; Radtke, M.; Alram, M.; Schindel, N.

    2011-12-01

    Four hundred sixteen silver coins stemming from the Ottoman Empire (16th and 17th centuries) were analyzed in order to confirm the fineness of the coinage as well as to study the provenance of the alloy used for the coins. As most of the coins showed the typical green patina on their surfaces due to corrosion processes which have led to the depletion of copper in the near-surface domains of the silver coins in comparison to their core composition, small samples by cutting splinters from the coins had to be taken, embedded in synthetic resin and cross-sectioned in order to investigate the true-heart metal composition. The type of the alloy was investigated as well as if coins minted in different locations demonstrated homogeneous traits concerning the predominant impurities which could suggest a common ore. Several X-ray based techniques (μ-XRF, μ-SRXRF and μ-PIXE) could be applied in order to determine the silver contents as well as the minor and trace elements. Finally, SEM/EDX was applied in order to study the homogeneity/heterogeneity of the coins and the presence of surface enrichments. In general, the silver content of the analyzed specimen varies between 90% and 95%. These outcomes have not supported the historical interpretations, which predict that during the period studied a debasement of approximately 44% of the silver content of the coins should have occurred.

  6. Characterization of the silver coins of the Hoard of Beçin by X-ray based methods

    International Nuclear Information System (INIS)

    Four hundred sixteen silver coins stemming from the Ottoman Empire (16th and 17th centuries) were analyzed in order to confirm the fineness of the coinage as well as to study the provenance of the alloy used for the coins. As most of the coins showed the typical green patina on their surfaces due to corrosion processes which have led to the depletion of copper in the near-surface domains of the silver coins in comparison to their core composition, small samples by cutting splinters from the coins had to be taken, embedded in synthetic resin and cross-sectioned in order to investigate the true-heart metal composition. The type of the alloy was investigated as well as if coins minted in different locations demonstrated homogeneous traits concerning the predominant impurities which could suggest a common ore. Several X-ray based techniques (μ-XRF, μ-SRXRF and μ-PIXE) could be applied in order to determine the silver contents as well as the minor and trace elements. Finally, SEM/EDX was applied in order to study the homogeneity/heterogeneity of the coins and the presence of surface enrichments. In general, the silver content of the analyzed specimen varies between 90% and 95%. These outcomes have not supported the historical interpretations, which predict that during the period studied a debasement of approximately 44% of the silver content of the coins should have occurred.

  7. Polystyrene Based Silver Selective Electrodes

    Directory of Open Access Journals (Sweden)

    Shiva Agarwal

    2002-06-01

    Full Text Available Silver(I selective sensors have been fabricated from polystyrene matrix membranes containing macrocycle, Me6(14 diene.2HClO4 as ionophore. Best performance was exhibited by the membrane having a composition macrocycle : Polystyrene in the ratio 15:1. This membrane worked well over a wide concentration range 5.0×10-6–1.0×10-1M of Ag+ with a near-Nernstian slope of 53.0 ± 1.0 mV per decade of Ag+ activity. The response time of the sensor is <15 s and the membrane can be used over a period of four months with good reproducibility. The proposed electrode works well in a wide pH range 2.5-9.0 and demonstrates good discriminating power over a number of mono-, di-, and trivalent cations. The sensor has also been used as an indicator electrode in the potentiometric titration of silver(II ions against NaCl solution. The sensor can also be used in non-aqueous medium with no significant change in the value of slope or working concentration range for the estimation of Ag+ in solution having up to 25% (v/v nonaqueous fraction.

  8. Comparative Assessment of Antimicrobial Efficiency of Ionic Silver, Silver Monoxide, and Metallic Silver Incorporated onto an Aluminum Oxide Nanopowder Carrier

    OpenAIRE

    Agnieszka Maria Jastrzębska; Ewa Karwowska; Andrzej R. Olszyna; Antoni R. Kunicki

    2013-01-01

    The present paper provides comparative assessment of antimicrobial efficiency of ionic silver (Ag+), silver monoxide (Ag2O), and metallic silver (Ag) incorporated onto an aluminum oxide nanopowder carrier (Al2O3). The deposition of Ag+ ions, Ag2O nanoparticles, and Ag nanoparticles on an different phases of aluminum oxide nanopowder carrier was realized using consecutive stages of dry sol-gel method. The Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders were widely characterized qualitatively a...

  9. Parasitism and body condition in humpback chub from the Colorado and Little Colorado Rivers, Grand Canyon, Arizona

    Science.gov (United States)

    Hoffnagle, T.; Choudhury, Anindo; Cole, R.A.

    2006-01-01

    Glen Canyon Dam has greatly altered the Colorado River in Grand Canyon. The Little Colorado River (LCR) provides a small refuge of seasonally warm and turbid water that is thought to be more suitable than the Colorado River for endangered humpback chub Gila cypha. However, the LCR has low productivity and contains nonnative fishes and parasites, which pose a threat to humpback chub. The Colorado River hosts a different suite of nonnative fishes and is cold and clear but more productive. We compared condition factor (K), abdominal fat index (AFI), and presence and number of two introduced pathogenic parasites (Lernaea cyprinacea and Bothriocephalus acheilognathi) between juvenile (parasitism and poorer body condition in humpback chub from the LCR challenge the paradigm that warmer LCR waters are more suitable for humpback chub than the colder Colorado River and indicate the need to consider the importance and benefits of all available habitats, as well as biotic and abiotic factors, when managing endangered species and their environment.

  10. Epidemiologic characterization of Colorado backyard bird flocks.

    Science.gov (United States)

    Smith, Emily I; Reif, John S; Hill, Ashley E; Slota, Katharine E; Miller, Ryan S; Bjork, Kathe E; Pabilonia, Kristy L

    2012-06-01

    Backyard gallinaceous bird flocks may play an important role in the spread of infectious diseases within poultry populations as well as the transmission of zoonotic diseases to humans. An epidemiologic characterization was conducted of Colorado backyard flocks to gather information on general flock characteristics, human movement of birds, human-bird interaction, biosecurity practices, and flock health. Our results suggest that backyard poultry flocks in Colorado are small-sized flocks (68.6% of flocks had production for the family (86.44%) or as pet or hobby birds (42.27%). The backyard flock environment may promote bird-to-bird transmission as well as bird-to-human transmission of infectious disease. Birds are primarily housed with free access to the outside (96.85%), and many are moved from the home premises (46.06% within 1 yr). Human contact with backyard flocks is high, biosecurity practices are minimal, and bird health is negatively impacted by increased movement events. Increased knowledge of backyard bird characteristics and associated management practices can provide guidelines for the development of measures to decrease disease transmission between bird populations, decrease disease transmission from birds to humans, and increase the overall health of backyard birds. PMID:22856180

  11. Silver Nanoparticles and Graphitic Carbon Through Thermal Decomposition of a Silver/Acetylenedicarboxylic Salt

    Directory of Open Access Journals (Sweden)

    Komninou Philomela

    2009-01-01

    Full Text Available Abstract Spherically shaped silver nanoparticles embedded in a carbon matrix were synthesized by thermal decomposition of a Ag(I/acetylenedicarboxylic acid salt. The silver nanoparticles, which are formed either by pyrolysis at 300 °C in an autoclave or thermolysis in xylene suspension at reflux temperature, are acting catalytically for the formation of graphite layers. Both reactions proceed through in situ reduction of the silver cations and polymerization of the central acetylene triple bonds and the exact temperature of the reaction can be monitored through DTA analysis. Interestingly, the thermal decomposition of this silver salt in xylene partly leads to a minor fraction of quasicrystalline silver, as established by HR-TEM analysis. The graphitic layers covering the silver nanoparticles are clearly seen in HR-TEM images and, furthermore, established by the presence of sp2carbon at the Raman spectrum of both samples.

  12. Evaluation of optimal silver amount for the removal of methyl iodide on silver-impregnated adsorbents

    International Nuclear Information System (INIS)

    The adsorption characteristics of methyl iodide generated from the simulated off-gas stream on various adsorbents such as silver-impregnated zeolite (AgX), zeocarbon and activated carbon were investigated. An extensive evaluation was made on the optimal silver impregnation amount for the removal of methyl iodide at temperatures up to 300 deg. C. The degree of adsorption efficiency of methyl iodide on silver-impregnated adsorbent is strongly dependent on impregnation amount and process temperature. A quantitative comparison of adsorption efficiencies on three adsorbents in a fixed bed was investigated. The influence of temperature, methyl iodide concentration and silver impregnation amount on the adsorption efficiency is closely related to the pore characteristics of adsorbents. It shows that the effective impregnation ratio was about 10wt%, based on the degree of silver utilization for the removal of methyl iodide. The practical applicability of silver-impregnated zeolite for the removal of radioiodine generated from the DUPIC process was consequently proposed. (author)

  13. Fire Severity Controlled Susceptibility to a 1940s Spruce Beetle Outbreak in Colorado, USA

    Science.gov (United States)

    Kulakowski, Dominik; Veblen, Thomas T.; Bebi, Peter

    2016-01-01

    The frequency, magnitude, and size of forest disturbances are increasing globally. Much recent research has focused on how the occurrence of one disturbance may affect susceptibility to subsequent disturbances. While much has been learned about such linked disturbances, the strength of the interactions is likely to be contingent on the severity of disturbances as well as climatic conditions, both of which can affect disturbance intensity and tree resistance to disturbances. Subalpine forests in western Colorado were affected by extensive and severe wildfires in the late 19th century and an extensive and severe outbreak of spruce beetle (Dendroctonus rufipennis) in the 1940s. Previous research found that most, but not all, of the stands that burned and established following the late 19th century fires were not susceptible to the 1940s outbreak as beetles preferentially attack larger trees and stands in advanced stages of development. However, previous research also left open the possibility that some stands that burned and established following the 19th century fires may have been attacked during the 1940s outbreak. Understanding how strongly stand structure, as shaped by disturbances of varying severity, affected susceptibility to past outbreaks is important to provide a baseline for assessing the degree to which recent climate change may be relaxing the preferences of beetles for larger trees and for stands in latter stages of structural development and thereby changing the nature of linked disturbances. Here, dendroecological methods were used to study disturbance history and tree age of stands in the White River National Forest in Western Colorado that were identified in historical documents or remotely-sensed images as having burned in the 19th century and having been attacked by spruce beetle in the 1940s. Dendroecological reconstructions indicate that in young post-fire stands only old remnant trees that survived the otherwise stand-replacing fires were

  14. FROM THE SIGNIFICANT ST. JOACHIMSTAL SILVER AND URANIUM PIT, JÁCHYMOV, TO RADON SPA IN SAXON CZECH „RUDNA GORA“

    Directory of Open Access Journals (Sweden)

    Branislav Šebečić

    2006-12-01

    Full Text Available At he beginning of the 16th century Saxon miners discovered silver ore in the small settlement Konnradsgrűn at south-west slopes of Erzgebirge in the valley Joachimsthal named after the patron saint St. Joachim. The silver coin was named Jochymst(haler. The mine and the settlement became a free royal mining city where, thanks to the mint, one of the richest noble families von Schlick arose. 554,44 tons of silver were produced from 1517 till 1900. Together with silver ore cobalt and lead ore were exploited ( in significant quantities from 18th till 19th century and after that period nickel, bismuth and arsenic ore (19th century. From the listed ores cobalt was produced in largest quantities for enamel production; 1824,23 tons in the period from 1775 till 1851. Next to these ores uranite ore (urani/ni/t was discovered in the mine. The ore was first used to produce uranium colours used for ceramics, glass and paintings and later to obtain uranium; 8500 tons since 1853 till 1964, a part of which was worked up into radium, to obtain 100gr Ra-. Thanks to the discovery of radioactive- radon water the mine is still active because 20 miners are employed to maintain the part of it from which the radon water is exploited. Jachymov and its surroundigs have become a famous radioactive thermal sanatorium in Europe (the paper is published in Croatian.

  15. Preparation of silver powder through glycerol process

    Indian Academy of Sciences (India)

    Amit Sinha; B P Sharma

    2005-06-01

    High purity fine silver powder with uniform particle morphology was prepared through glycerol process. The process involves reduction of silver nitrate by glycerol under atmospheric conditions at a temperature below 175°C. Glycerol, in this process, acts as a solvent as well as a reducing agent. The powders prepared through this process were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and chemical analysis. The powders were well crystalline and contained oxygen, carbon and hydrogen as impurities. Overall purity was better than 99.9%. The yield of silver powder was better than 99%.

  16. Synthesis and characterization of nanophased silver tungstate

    Indian Academy of Sciences (India)

    Thresiamma George; Sunny Joseph; Suresh Mathew

    2005-11-01

    Silver tungstate (Ag2WO4) nanoparticles in two different morphologies are prepared by controlling the reaction kinetics of aqueous precipitation. X-ray diffraction studies reveal that the silver tungstate nanoparticles are in the -phase. SEM images show the rod-like and fiber-like morphologies of the nanoparticles with high aspect ratios. The TGA and DTA studies show the high thermal stability of the nanorods. The average crystallite sizes (20–30 nm) of the rod-like silver tungstate estimated from TEM is consistent with the XRD results.

  17. Interaction of (-)-epigallocatechin gallate with silver nanoparticles

    CERN Document Server

    Chandra, Goutam Kumar; Dasgupta, Swagata; Roy, Anushree

    2010-01-01

    Interactions between silver nanoparticles and (-)-epigallocatechin gallate (EGCG) have been investigated. Prior to the addition of EGCG molecules the silver particles are stabilized by borate ions. Studies on the surface plasmon resonance band of silver particles suggest that the EGCG molecules remove the borate ions from the surface of the metal particles due to the chelating property of the ions. The complex formation by EGCG and borate ions has been confirmed by NMR studies and pH titration. A possible scheme of interaction between the two has been proposed.

  18. Preparation of Silver Nanostructures from Bicontinuous Microemulsions

    OpenAIRE

    Pedroza-Toscano, M. A.; Rabelero-Velasco, M.; Díaz de León, R.; H. Saade; R. G. López; E. Mendizábal; Puig, J. E.

    2012-01-01

    Precipitation of silver nanoparticles at 70°C was carried out by dosing a 1.3 M sodium borohydride aqueous solution over bicontinuous microemulsions formed with a mixture of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) and sodium dodecylsulfate (SDS) as surfactants, a 0.5 M silver nitrate aqueous solution, and toluene. Weight ratios of 2.5/1 and 3/1 AOT/SDS were used in the precipitation reactions. Silver nanoparticles were characterized by transmission electronic microscopy, X-ray diffracti...

  19. Polyamide/silver antimicrobials: effect of crystallinity on the silver ion release

    OpenAIRE

    Kumar, Radhesh; Münstedt, Helmut

    2005-01-01

    Abstract: Polyamide/silver (PA/Ag) compositematerials are regarded as potential antimicrobials by virtue of their efficacy to release the Ag+ ions in an aqueous medium. The effects of the matrix crystallinity on the Ag+ ion release characteristics of PA/Ag composites are discussed. It is found that matrix crystallinity is very decisive for the silver ion releasing properties and hence the antimicrobial efficacy of silver-based antimicrobial polyamides. The crystallinities of the c...

  20. Synthesis of silver nanoparticles and antibacterial property of silk fabrics treated by silver nanoparticles

    OpenAIRE

    ZHANG, GUANGYU; Liu, Yan; Gao, Xiaoliang; Chen, Yuyue

    2014-01-01

    A silver nanoparticle solution was prepared in one step by mixing AgNO3 and a multi-amino compound (RSD-NH2) solution under ambient condition. RSD-NH2 was in-house synthesized by methacrylate and polyethylene polyamine in methanol, which has abundant amino and imino groups. However, the characterization of silver nanoparticles indicated that these nanoparticles are easy to agglomerate in solution. Therefore, an in situ synthesis method of silver nanoparticles on the silk fabrics was developed...

  1. Irradiation of silver and agar/silver nanoparticles with argon, oxygen glow discharge plasma, and mercury lamp

    OpenAIRE

    Ahmad, Mahmoud M; Abdel-Wahab, Essam A; El-Maaref, A A; Rawway, Mohammed; Shaaban, Essam R

    2014-01-01

    The irradiation effect of argon, oxygen glow discharge plasma, and mercury lamp on silver and agar/silver nanoparticle samples is studied. The irradiation time dependence of the synthesized silver and agar/silver nanoparticle absorption spectra and their antibacterial effect are studied and compared. In the agar/silver nanoparticle sample, as the irradiation time of argon glow discharge plasma or mercury lamp increases, the peak intensity and the full width at half maximum, FWHM, of the surfa...

  2. Comparison of bioconcentration of ionic silver and silver nanoparticles in zebrafish eleutheroembryos

    International Nuclear Information System (INIS)

    The production of silver nanoparticles has reached nowadays high levels. Bioconcentration studies, information on persistence and toxicity are fundamental to assess their global risk and thus necessary to establish legislations regarding their use. Previous studies on silver nanoparticle toxicity have determined a clear correlation between their chemical stability and toxicity. In this work, experimental conditions able to assure silver nanoparticles stability have been optimized. Then, zebrafish (Danio rerio) eleutheroembryos were exposed to ionic silver and to Ag NPs for comparison purposes. A protocol alternative to the OECD 305 technical guideline was used. To determine silver concentration in both the eleutheroembryos and the exposure media, an analytical method consisting in ultrasound assisted extraction, followed by inductively coupled plasma mass spectrometry and graphite furnace atomic absorption spectrometry, was developed. Then, bioconcentration factors were calculated. The results revealed that ionic silver was more accumulative for zebrafish eleutheroembryos than nanoparticles at the levels tested. - Highlights: • Silver nanoparticles stability study in aqueous media. • Evidence of the high divergence in the bioaccumulation studies already published. • Possible alternative to the Bioconcentration Test OECD 305. - Different patterns on accumulation by zebrafish eleutheroembryos of ionic silver and silver nanoparticles have been observed following OECD 305 technical guidelines

  3. Ultrastructural localization of silver in rat testis and organ distribution of radioactive silver in the rat

    DEFF Research Database (Denmark)

    Ernst, E; Rungby, J; Baatrup, E

    1992-01-01

    , concentrations in organs remained almost stable throughout the experimental period. Silver was especially abundant in interstitial macrophages and in the basement membrane. Deposits of silver were found in all cell types of spermatogenesis and in the lysosomes of the Sertoli cells. Udgivelsesdato: 1991-Oct......The deposition of silver after a single intravenous injection (2 micrograms Ag g-1 body weight) was studied in the testes of Wistar rats 24 h and 1 and 2 weeks after dosing with radiolabelled 110AgNo3 (2 micrograms Ag and 1.2 kBq g-1 body weight). Also, the temporal accumulation of silver during...

  4. Preparations and characterization of alginate/silver composite films: Effect of types of silver particles.

    Science.gov (United States)

    Shankar, Shiv; Wang, Long-Feng; Rhim, Jong-Whan

    2016-08-01

    Alginate-based films reinforced with different types of silver particles such as metallic silver (AgM), silver zeolite (AgZ), citrate reduced silver nanoparticles (AgNP(C)), laser ablated silver nanoparticles (AgNP(LA)), and silver nitrate (AgNO3) were prepared using a solvent casting method and the effect of silver particles on the optical, mechanical, water vapor barrier, and antimicrobial properties the composite films was evaluated. Size and shape of the silver particles were varied depending on the types of silver source and the preparation method. The alginate films incorporated with AgNP(C), AgNP(LA), and AgNO3 showed a characteristic surface plasmon resonance absorption peaks of AgNPs around 420nm. Film properties such as mechanical, optical, and water vapor barrier properties were greatly influenced by the types of AgNPs used. Alginate/AgNPs composite films except AgM and AgNP(LA) incorporated ones exhibited strong antimicrobial activity against two food-borne pathogenic bacteria, Escherichia coli and Listeria monocytogenes. The developed films have a high potential for the application as antimicrobial food packaging films. PMID:27112867

  5. Tuning Properties in Silver Clusters

    KAUST Repository

    Joshi, Chakra P

    2015-07-09

    The properties of Ag nanoclusters are not as well understood as those of their more precious Au cousins. However, a recent surge in the exploration of strategies to tune the physicochemical characteristics of Ag clusters addresses this imbalance, leading to new insights into their optical, luminescence, crystal habit, metal-core, ligand-shell and environmental properties. In this Perspective, we provide an overview of the latest strategies along with a brief introduction of the theoretical framework necessary to understand the properties of silver nanoclusters and the basis for their tuning. The advances in cluster research and the future prospects presented in this Perspective will eventually guide the next large systematic study of nanoclusters, resulting in a single collection of data similar to the periodic table of elements.

  6. Tuning Properties in Silver Clusters.

    Science.gov (United States)

    Joshi, Chakra P; Bootharaju, Megalamane S; Bakr, Osman M

    2015-08-01

    The properties of Ag nanoclusters are not as well understood as those of their more precious Au cousins. However, a recent surge in the exploration of strategies to tune the physicochemical characteristics of Ag clusters addresses this imbalance, leading to new insights into their optical, luminescence, crystal habit, metal-core, ligand-shell, and environmental properties. In this Perspective, we provide an overview of the latest strategies along with a brief introduction of the theoretical framework necessary to understand the properties of silver nanoclusters and the basis for their tuning. The advances in cluster research and the future prospects presented in this Perspective will eventually guide the next large systematic study of nanoclusters, resulting in a single collection of data similar to the periodic table of elements. PMID:26267198

  7. Shaped gold and silver nanoparticles

    Science.gov (United States)

    Sun, Yugang; An, Changhua

    2011-03-01

    Advance in the synthesis of shaped nanoparticles made of gold and silver is reviewed in this article. This review starts with a new angle by analyzing the relationship between the geometrical symmetry of a nanoparticle shape and its internal crystalline structures. According to the relationship, the nanoparticles with well-defined shapes are classified into three categories: nanoparticles with single crystallinity, nanoparticles with angular twins, and nanoparticles with parallel twins. Discussion and analysis on the classical methods for the synthesis of shaped nanoparticles in each category are also included and personal perspectives on the future research directions in the synthesis of shaped metal nanoparticles are briefly summarized. This review is expected to provide a guideline in designing the strategy for the synthesis of shaped nanoparticles and analyzing the corresponding growth mechanism.

  8. Neutron scattering and models: Silver

    International Nuclear Information System (INIS)

    Differential neutron elastic-scattering cross sections of elemental silver were measured from 1.5 → 10 MeV at ∼ 100 keV intervals up to 3 MeV, at ∼ 200 keV intervals from 3 → 4 MeV, and at ∼ 500 keV intervals above 4 MeV. At ≤ 4 MeV the angular range of the measurements was ∼ 200 → 1600 with 10 measured values below 3 MeV and 20 from 3 → 4 MeV at each incident energy. Above 4 MeV ≥ 40 scattering angles were used distributed between ∼ 170 and 160 All of the measured elastic distributions included some contributions due to inelastic scattering. Below 4 MeV the measurements determined cross sections for ten inelastically-scattered neutron groups corresponding to observed excitations of 328 ± 13, 419 ± 50, 748 ± 25, 908 ± 26, 115 ± 38, 1286 ± 25, 1507 ± 20, 1632 ± 30, 1835 ± 20 and 1944 ± 26 keV. All of these inelastic groups probably were composites of contributions from the two isotopes 107Ag and 109Ag. The experimental results were interpreted in terms of the spherical optical model and of rotational and vibrational coupled-channels models, and physical implications are discussed. In particular, the neutron-scattering results are consistent with a ground-state rotational band with a quadrupole deformation Β2 = 0.20 ± ∼ 10% for both of the naturally-occurring silver isotopes

  9. Green synthesis of silver nanoparticles using tannins

    Science.gov (United States)

    Raja, Pandian Bothi; Rahim, Afidah Abdul; Qureshi, Ahmad Kaleem; Awang, Khalijah

    2014-09-01

    Colloidal silver nanoparticles were prepared by rapid green synthesis using different tannin sources as reducing agent viz. chestnut (CN), mangrove (MG) and quebracho (QB). The aqueous silver ions when exposed to CN, MG and QB tannins were reduced which resulted in formation of silver nanoparticles. The resultant silver nanoparticles were characterized using UV-Visible, X-ray diffraction (XRD), scanning electron microscopy (SEM/EDX), and transmission electron microscopy (TEM) techniques. Furthermore, the possible mechanism of nanoparticles synthesis was also derived using FT-IR analysis. Spectroscopy analysis revealed that the synthesized nanoparticles were within 30 to 75 nm in size, while XRD results showed that nanoparticles formed were crystalline with face centered cubic geometry.

  10. Ellipsometric Studies on Silver Telluride Thin Films

    Directory of Open Access Journals (Sweden)

    M. Pandiaraman

    2011-01-01

    Full Text Available Silver telluride thin films of thickness between 45 nm and 145 nm were thermally evaporated on well cleaned glass substrates at high vacuum better than 10 – 5 mbar. Silver telluride thin films are polycrystalline with monoclinic structure was confirmed by X-ray diffractogram studies. AFM and SEM images of these films are also recorded. The phase ratio and amplitude ratio of these films were recorded in the wavelength range between 300 nm and 700 nm using spectroscopic ellipsometry and analysed to determine its optical band gap, refractive index, extinction coefficient, and dielectric functions. High absorption coefficient determined from the analysis of recorded spectra indicates the presence of direct band transition. The optical band gap of silver telluride thin films is thickness dependent and proportional to square of reciprocal of thickness. The dependence of optical band gap of silver telluride thin films on film thickness has been explained through quantum size effect.

  11. Sealed Cylindrical Silver/Zinc Batteries Project

    Data.gov (United States)

    National Aeronautics and Space Administration — RBC Technologies has significanly improved the cycle life and wet life of silver/zinc battery technology through novel separator and anode formulations. This...

  12. Tartu on Eesti Boston / Silver Meikar

    Index Scriptorium Estoniae

    Meikar, Silver, 1978-

    2007-01-01

    Tartu eeldustest kujuneda hariduse, innovaatilise tootmise, pärimuskultuuri ja linnaruumi tasakaalustatud kasutamise südameks. Ettevõtluse, transpordi ja turismi arengust. Lisa: Silver Meikari Lõuna-Eesti edu top 10

  13. Realistic Silver Optical Constants for Plasmonics.

    Science.gov (United States)

    Jiang, Yajie; Pillai, Supriya; Green, Martin A

    2016-01-01

    Silver remains the preferred conductor for optical and near-infrared plasmonics. Many high-profile studies focus exclusively on performance simulation in such applications. Almost invariably, these use silver optical data either from Palik's 1985 handbook or, more frequently, an earlier Johnson and Christy (J&C) tabulation. These data are inconsistent, making it difficult to ascertain the reliability of the simulations. The inconsistency stems from challenges in measuring representative properties of pristine silver, due to tarnishing on air exposure. We demonstrate techniques, including use of silicon-nitride membranes, to access the full capabilities of multiple-angle, spectrometric-ellipsometry to generate an improved data set, representative of overlayer-protected, freshly-deposited silver films on silicon-nitride and glass. PMID:27470307

  14. Alternative Plasmonic Materials: Beyond Gold and Silver

    DEFF Research Database (Denmark)

    Naik, Gururaj V.; Shalaev, Vladimir M.; Boltasseva, Alexandra

    2013-01-01

    as gold and silver, that exhibit metallic properties and provide advantages in device performance, design flexibility, fabrication, integration, and tunability. This review explores different material classes for plasmonic and metamaterial applications, such as conventional semiconductors...

  15. 'Chrysanthemum petal' arrangements of silver nano wires.

    Science.gov (United States)

    Cui, Hui-Wang; Jiu, Jin-Ting; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki; Uchida, Hiroshi

    2014-12-01

    Highly ordered 'Chrysanthemum petal' arrangements of silver nano wires were fabricated in a biodegradable polymer of polyvinyl alcohol using a simple one-step blending method without any template. The degree of the arrangement increased with the decreasing content of polyvinyl alcohol. The mechanism for the formation of these 'Chrysanthemum petal' arrangements was discussed specifically. These 'Chrysanthemum petal' arrangements will be helpful to increase the electrical conductivity of silver nano wires films. PMID:25397618

  16. Electrocatalytic activity of bismuth doped silver electrodes

    CERN Document Server

    Amjad, M

    2002-01-01

    Investigation of redox reactions on silver, and bismuth doped silver electrodes in aqueous KOH solutions, by using potentiostatic steady-state polarization technique, has been carried out. The redox wave potential and current displacements along with multiplicity of the latter have been examined. These electrodes were employed for the oxidation of organic molecules such as ethylamine in alkaline media. Subsequently, these electrodes were ranked with respect to their activity for the redox reactions. (author)

  17. Selective Electroless Silver Deposition on Graphene Edges

    DEFF Research Database (Denmark)

    Durhuus, D.; Larsen, M. V.; Andryieuski, Andrei;

    2015-01-01

    We demonstrate a method of electroless selective silver deposition on graphene edges or between graphene islands without covering the surface of graphene. Modifications of the deposition recipe allow for decoration of graphene edges with silver nanoparticles or filling holes in damaged graphene...... on silica substrate and thus potentially restoring electric connectivity with minimal influence on the overall graphene electrical and optical properties. The presented technique could find applications in graphene based transparent conductors as well as selective edge functionalization and can be extended...

  18. Fluorescent DNA-templated silver nanoclusters

    Science.gov (United States)

    Lin, Ruoqian

    Because of the ultra-small size and biocompatibility of silver nanoclusters, they have attracted much research interest for their applications in biolabeling. Among the many ways of synthesizing silver nanoclusters, DNA templated method is particularly attractive---the high tunability of DNA sequences provides another degree of freedom for controlling the chemical and photophysical properties. However, systematic studies about how DNA sequences and concentrations are controlling the photophysical properties are still lacking. The aim of this thesis is to investigate the binding mechanisms of silver clusters binding and single stranded DNAs. Here in this thesis, we report synthesis and characterization of DNA-templated silver nanoclusters and provide a systematic interrogation of the effects of DNA concentrations and sequences, including lengths and secondary structures. We performed a series of syntheses utilizing five different sequences to explore the optimal synthesis condition. By characterizing samples with UV-vis and fluorescence spectroscopy, we achieved the most proper reactants ratio and synthesis conditions. Two of them were chosen for further concentration dependence studies and sequence dependence studies. We found that cytosine-rich sequences are more likely to produce silver nanoclusters with stronger fluorescence signals; however, sequences with hairpin secondary structures are more capable in stabilizing silver nanoclusters. In addition, the fluorescence peak emission intensities and wavelengths of the DNA templated silver clusters have sequence dependent fingerprints. This potentially can be applied to sequence sensing in the future. However all the current conclusions are not warranted; there is still difficulty in formulating general rules in DNA strand design and silver nanocluster production. Further investigation of more sequences could solve these questions in the future.

  19. Characterisations of collagen-silver-hydroxyapatite nanocomposites

    Science.gov (United States)

    Ciobanu, C. S.; Popa, C. L.; Petre, C. C.; Jiga, G.; Trusca, R.; Predoi, D.

    2016-05-01

    The XRD analysis were performed to confirm the formation of hydroxyapatite structure in collagen-silver-hydroxyapatite nanocomposites. The molecular interaction in collagen-hydroxyapatite nanocomposites was highlighted by Fourier transform infrared spectroscopy (FTIR) analysis. The SEM showed a nanostructure of collagen-silverhydroxyapatite nanocomposites composed of nano needle-like particles in a veil with collagen texture. The presence of vibrational groups characteristics to the hydroxyapatite structure in collagen-silver-hydroxyapatite (AgHApColl) nanocomposites was investigated by FTIR.

  20. 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.

  1. Ponnequin Wind Energy Project Weld County, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-08-01

    The purpose of this environmental assessment (EA) is to provide the U.S. Department of Energy (DOE) and the public with information on potential environmental impacts associated with the development of the Ponnequin Wind Energy Project in Colorado. This EA and public comments received on it will be used in DOE`s deliberations on whether to release funding for the project. This document provides a detailed description of the proposed project and an assessment of potential impacts associated with its construction and operations. Resources and conditions considered in the analysis include streams; wetlands; floodplains; water quality; soils; vegetation; air quality; socioeconomic conditions; energy resources; noise; transportation; cultural resources; visual and land use resources; public health and safety; wildlife; threatened, endangered, and candidate species; and cumulative impacts. The analysis found that the project would have minimal impacts on these resources and conditions, and would not create impacts that exceed the significance criteria defined in this document. 90 refs., 5 figs.

  2. Environmental geology of the Summitville mine, Colorado

    Science.gov (United States)

    Gray, John E.; Coolbaugh, Mark F.; Plumlee, Geoffrey S.; Atkinson, William W.

    1994-01-01

    Although altered and mineralized rocks at Summitville mine in Colorado contain minimal amount of sulfide minerals, acid mine problems existed primarily because of the pervasive alteration of the surrounding rocks, through hydrothermal process, to highly siliceous and argillized rocks that are incapable of buffering acidic waters during weathering. The problems are compounded by the continued exposure of altered and mineralized rocks in open pit, heap leach pad and waste piles to oxygenated waters. Inadequate subsurface structural control and underground mine workings also greatly affect water quality and the location of acid mine drainage output. It is expected that with these initial results, geological studies on constrained acid-generation from ore and altered rocks will be pursued.

  3. Dike rocks of the Apishapa Quadrangle, Colorado

    Science.gov (United States)

    Cross, Whitman

    1915-01-01

    The Apishapa quadrangle, the geographic relations of which are shown by Plate IV, is situated on the plains south of Arkansas River, in Colorado, about 24 miles east of the mountain front. The geology of the Pueblo, Walsenburg, Spanish Peaks, and Elmoro quadrangles, adjoining it on the northwest, west, southwest, and south, respectively, has been described in folios of the Geologic Atlas. G. K. Gilbert, assisted by F. P. Gulliver and G. W. Stose, took up the survey of the Apishapa area in 1894. The Apishapa folio was completed by Stose and was issued in 1913. The rocks to be described in this paper were collected by Gilbert and his assistants, the present writer never having visited the area. The following description of the occurrence of the has been kindly furnished by Mr. Stose.

  4. Pulsed EPR for studying silver clusters

    Science.gov (United States)

    Michalik, J.; Wasowicz, T.; Sadlo, J.; Reijerse, E. J.; Kevan, L.

    1996-01-01

    The cationic silver clusters of different nuclearity have been produced by radiolysis of zeolite A and SAPO molecular sieves containing Ag + as exchangeable cations. The pulsed EPR spectroscopy has been applied for studying the local environment of silver cluster in order to understand the mechanism of cluster formation and stabilization. The electron spin echo modulation (ESEM) results on Ag 6n+ cluster in dehydration zeolite A indicate that the hexameric silver is stabilized only in sodalite cages which are surrounded by α-cages containing no water molecules. Trimeric silver clusters formed in hydrated A zeolites strongly interact with water, thus the paramagnetic center can be considered as a cluster-water adduct. In SAPO-molecular sieves, silver clusters are formed only in the presence of adsorbed alcohol molecules. From ESEM it is determined that Ag 4n+ in SAPO-42 is stabilized in α-cages, where it is directly coordinated by two methanol molecules. Dimeric silver, Ag 2+ in SAPO-5 and SAPO-11 is located in 6-ring channels and interacts with three CH 3OH molecules, each in different 10-ring or 12-ring channels. The differences of Ag 2+ stability in SAPO-5 and SAPO-11 are also discussed.

  5. Pulsed EPR for studying silver clusters

    International Nuclear Information System (INIS)

    The cationic silver clusters of different nuclearity have been produced by radiolysis of zeolite A and SAPO molecular sieves containing Ag+ as exchangeable cations. The pulsed EPR spectroscopy has been applied for studying the local environment of silver cluster in order to understand the mechanism of cluster formation and stabilization. the electron spin echo modulation (ESEM) results on Ag6n+ cluster in dehydration zeolite A indicate that the hexameric silver is stabilized only in sodalite cages which are surrounded by α-cages containing no water molecules. Trimeric silver clusters formed in hydrated A zeolites strongly interact with water, thus the paramagnetic center can be considered as a cluster-water adduct. In SAPO-molecular sieves, silver clusters are formed only in the presence of adsorbed alcohol molecules. From ESEM it is determined that Ag4n+ in SAPO-42 is stabilized in α cages, where it is directly coordinated by two methanol molecules. Dimeric silver, Ag2+ in SAPO-5 and SAPO-11 is located in 6-ring channels and interacts with three CH3OH molecules, each in different 10 ring or 12 ring channels. The differences of Ag2+ stability in SAPO-5 and SAPO-11 are also discussed. (Author)

  6. Adsorption of iodine on silver wire

    International Nuclear Information System (INIS)

    It is an important process in which iodine is adsorbed on silver wire during the preparation of 125I seed sources. In this paper, a technique of adsorption of iodine on silver wire was studied. The influence of several factors, such as the type of reagent for halogenation, the time for halogenation, the time for adsorption, pH value, ion concentration, carrier iodine and so on, on the utilization rate of 131I was investigated, and the effectiveness of our proposed technique for adsorption of iodine on silver wire was confirmed. The procedure is summarized as follows: silver wire acidification: using 4 mol/L HNO3 as halogenation agent, stirring acidified for 20 min; silver wire halogenation: used 2 mol/L NaClO3 as halogenated agent, halogenation for 3 h; adsorption of iodine on silver wire: room temperature, pH value for the reaction is about 3, the time for adsorption is 30 min, carrier iodine is 27.5 μg. Original radioactivity of reaction solution was determined based on radioactivity of source-core that user required. (authors)

  7. Activity of Antimicrobial Silver Polystyrene Nanocomposites

    Directory of Open Access Journals (Sweden)

    M. Palomba

    2012-01-01

    Full Text Available A simple technique based on doping polymers with in situ generated silver nanoparticles (Ag/PS films has been developed. In particular, an antiseptic material has been prepared by dissolving silver 1,5-cyclooctadiene-hexafluoroacetylacetonate in amorphous polystyrene, and the obtained solid solution has been heated for ca. 10 s at a convenient temperature (180°C. Under such conditions the metal precursor decomposes producing silver atoms that diffuse into the polymer and clusterize. The antimicrobial characteristics of the resulting polystyrene-based material have been accurately evaluated toward Escherichia coli (E. coli comparing the cytotoxicity effect of 10 wt.% and 30 wt.% (drastic and mild annealing silver-doped polystyrene to the corresponding pure micrometric silver powder. Two different bacterial viability assays were performed in order to demonstrate the cytotoxic effect of Ag/PS films on cultured E. coli: (1 turbidimetric determination of optical density; (2 BacLight fluorescence-based test. Both methods have shown that silver-doped polystyrene (30 wt.% provides higher antibacterial activity than pure Ag powder, under similar concentration and incubation conditions.

  8. Towards conducting inks: Polypyrrole–silver colloids

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Composite colloidal particles combining conducting polymer and metal have been prepared. • Conducting colloids are suitable for printing applications. • Polypyrrole/silver colloids are prepared in a single reaction step. • The conductivity control is discussed and still needs improvement. - Abstract: The oxidation of pyrrole with silver nitrate in the presence of suitable water-soluble polymers yields composite polypyrrole–silver colloids. The polypyrrole–silver nanoparticles stabilized with poly(N-vinylpyrrolidone) have a typical size around 350 nm and polydispersity index 0.20, i.e. a moderate polydispersity in size. Similar results have been obtained with poly(vinyl alcohol) as stabilizer. The effect of stabilizer concentration on the particle size is marginal. In the present study, several types of stabilizers have been tested in addition to currently used poly(N-vinylpyrrolidone). Transmission electron microscopy and optical microscopy revealed the gemini morphology of polypyrrole and silver colloidal nanoparticles and confirmed their size and size-distribution determined by dynamic light scattering. The use of colloidal dispersions provides an efficient tool for the UV–vis and FT Raman spectroscopic characterization of polypyrrole, including the transition between polypyrrole salt and corresponding polypyrrole base. The dispersions were used for the preparation of coatings on polyethylene terephthalate foils, and the properties for polypyrrole–silver composites have been compared with those produced from polypyrrole colloids alone

  9. Final Critical Habitat for the Colorado pikeminnow (Ptychocheilus lucius)

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — To provide the user with a general idea of areas where final critical habitat for Colorado pikeminnow (Ptychocheilus lucius) occur based on the description provided...

  10. Saturated thickness of the High Plains Aquifer, Colorado, 2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data are in support of report DS 472 (Arnold and others, 2009). This data set represents the saturated thickness of the High Plains aquifer within Colorado....

  11. Final Critical Habitat for the Little Colorado spinedace (Lepidomeda vittata)

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — provide the user with a general idea of areas where final critical habitat for Little Colorado spinedace (Lepidomeda vittata) occur based on the description...

  12. Excellence in Veterinary Medicine at Colorado State University

    Science.gov (United States)

    Tietz, William J.

    1977-01-01

    Colorado State University has developed a strong interdisciplinary faculty that provides the entire university with graduate and undergraduate instruction in the basic biomedical sciences--anatomy, physiology, and microbiology--in addition to instruction in the professional curriculum. (LBH)

  13. Corbiculae fluminea as a bioindicator on the Lower Colorado River

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Tissue samples from Asiatic clam (Corbimla fluminea) from the lower Colorado River were analyzed for trace element concentrations. Selenium and arsenic were...

  14. Mean-annual erosion potential for Colorado and New Mexico

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey Data Series provides raster data representing an estimate of the mean-annual erosion potential of a 30-meter raster cell in Colorado and...

  15. Colorado's hydrothermal resource base: an assessment

    Energy Technology Data Exchange (ETDEWEB)

    Pearl, R.H.

    1981-01-01

    As part of its effort to more accurately describe the nations geothrmal resource potential, the US Department of Energy/Division of Geothermal Energy contracted with the Colorado Geological survey to appraise the hydrothermal (hot water) geothermal resources of Colorado. Part of this effort required that the amount of energy that could possibly be contained in the various hydrothermal systems in Colorado be estimated. The findings of that assessment are presented. To make these estimates the geothermometer reservoir temperatures estimated by Barrett and Pearl (1978) were used. In addition, the possible reservoir size and extent were estimated and used. This assessment shows that the total energy content of the thermal systems in Colorado could range from 4.872 x 10{sup 15} BTU's to 13.2386 x 10{sup 15} BTU's.

  16. The Colorado Plateau coal assessment study area, 2000 (cpstdyg)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This is a coverage of the Colorado Plateau coal assessment study area. The study area outline was drawn on the county lines that most closely outline the...

  17. Photographs of historical mining operations in Colorado and Utah

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A collection of photographs of mine sites, mining operations, and tailings taken prior to 1980 at a variety of sites throughout Colorado and Utah. A database of...

  18. US Forest Service Roadless Areas: Colorado Roadless Rule

    Data.gov (United States)

    US Forest Service, Department of Agriculture — A map service, available on the www that depicts the boundaries of Roadless Areas designated by the Colorado Roadless Rule of 2012 and managed by the US Forest...

  19. Host plant preference in Colorado potato beetle (Coleoptera: Chrysomelidae)

    Science.gov (United States)

    Field and laboratory-choice tests were conducted to better understand host plant preference by the Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), in Virginia. In laboratory olfactometer studies, L. decemlineata preferred potato over both tomato and eggplant foli...

  20. Relaxation of the Silver/Silver Iodide Electrode in Aqueous Solution

    NARCIS (Netherlands)

    Peverelli, K.J.

    1979-01-01

    The aim of this study is to detect and characterize relaxation processes on silver/silver iodide electrodes in aqueous electrolyte solution. The information obtained is to be used for an estimation of the consequences of similar processes on colloidal AgI particles during encounter.In chapter 1 a ge

  1. Preparation of silver nanoparticles in solution from a silver salt by laser irradiation.

    Science.gov (United States)

    Abid, J P; Wark, A W; Brevet, P F; Girault, H H

    2002-04-01

    A new method is proposed for the fabrication of a well-defined size and shape distribution of silver nanoparticles in solution; the method employs direct laser irradiation of an aqueous solution containing a silver salt and a surfactant in the absence of reducing agents. PMID:12119726

  2. Preparation of sintered silver nanosheets by coating technique using silver carbamate complex

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Hee-Yong; Cha, Jae-Ryung; Gong, Myoung-Seon, E-mail: msgong@dankook.ac.kr

    2015-03-01

    This study describes a coating technique approach for large-scale preparation of sintered silver nanosheets whose lateral dimensions were controlled in the thickness range of 50–65 nm. These procedures involved coating water-soluble poly (vinyl alcohol) (PVA) and silver 2-ethylhexylcarbamate (Ag-EHC), as well as thermal reduction of a silver precursor by heating at 150 °C, followed by dissolving away the PVA layer with alcoholic water. When the silver carbamate layer on the PVA layer was heated to 150 °C, the silver carbamate layer was thermally reduced and directed to grow into uniform sintered nanosheets with aspect ratios as high as 1000. The multi-stacked PVA/Ag structures and sintered silver nanosheets were confirmed by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Measurements of the conductive property at room temperature indicated that these nanosheets were electrically continuous with a resistivity of approximately 7.3 × 10{sup −6} Ω cm. - Highlights: • A coating technique is used to make sintered Ag nanosheets. • PVA and silver carbamate act as a separation layer and a silver precursor. • The Ag nanosheets have thickness width 50–60 nm and width up to hundred μm. • The Ag nanosheets showed a resistivity of ca. 7.3 × 10{sup −6} Ω cm.

  3. Uranium hydrogeochemical and stream sediment reconnaissance in the San Juan Mountains, Southwest Colorado

    International Nuclear Information System (INIS)

    From 1995 sites in the San Juan Mountains area, 1706 water and 1982 sediment samples were collected during June--July 1976 and analyzed for uranium. The area includes the southern third of the Colorado mineral belt which has yielded rich ores of gold, silver, copper, lead, zinc, and molybdenum. The broadly domed mountains are capped by 2500 m of Tertiary volcanics, deeply eroded to expose a Precambrian crystalline core. Adjacent plateaus underlain by Mesozoic sedimentary rocks were included in the reconnaissance. Average value of uranium in water samples from mountains was less than 0.5 ppB, from plateaus was 1 to 2 ppB, from Mancos shale areas exceeded 2 ppB. Anomalous sediment samples, 40 ppM uranium, came from near Storm King Mountain and upper Vallecito Creek. Other anomalous areas, including the Lake City mining district, were well defined by 4 to 30 ppM uranium in sediment and 3 to 30 ppB uranium in water. Anomalous areas not previously reported indicate favorable areas for future exploration

  4. Uranium hydrogeochemical and stream sediment reconnaissance in the San Juan Mountains, Southwest Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, J.C.

    1977-02-01

    From 1995 sites in the San Juan Mountains area, 1706 water and 1982 sediment samples were collected during June--July 1976 and analyzed for uranium. The area includes the southern third of the Colorado mineral belt which has yielded rich ores of gold, silver, copper, lead, zinc, and molybdenum. The broadly domed mountains are capped by 2500 m of Tertiary volcanics, deeply eroded to expose a Precambrian crystalline core. Adjacent plateaus underlain by Mesozoic sedimentary rocks were included in the reconnaissance. Average value of uranium in water samples from mountains was less than 0.5 ppB, from plateaus was 1 to 2 ppB, from Mancos shale areas exceeded 2 ppB. Anomalous sediment samples, 40 ppM uranium, came from near Storm King Mountain and upper Vallecito Creek. Other anomalous areas, including the Lake City mining district, were well defined by 4 to 30 ppM uranium in sediment and 3 to 30 ppB uranium in water. Anomalous areas not previously reported indicate favorable areas for future exploration.

  5. Colorado's Voucher Law:Examining the Claim of Fiscal Neutrality

    OpenAIRE

    Kevin G. Welner

    2004-01-01

    Colorado's voucher law was declared unconstitutional by the Colorado Supreme Court on June 28, 2004. Voucher supporters have begun drafting revised legislation designed to address the legal problem. This article calls into question the key financial claim of revenue neutrality'a claim that was central to the promotion and passage of the departing voucher law. The author concludes that the voucher law was not revenue neutral, even though it attempts to exclude from eligibility those children a...

  6. Raton basin coalbed methane production picking up in Colorado

    Science.gov (United States)

    Hemborg, H. Thomas

    1996-01-01

    Coalbed methane production in the Raton basin of south-central Colorado and northeast New Mexico has gone over pilot testing and entered the development stage which is expected to last several years. The development work is restricted to roughly a 25 mile by 15 mile wide `fairway' centered about 20 miles west of Trinidad, Colorado. At last count, 85 wells were producing nearly 17.5 MMcfd of coalbed methane from the basin's Raton and Vermejo formation coals.

  7. The Colorado Plateau II : Biophysical, Socioeconomic, and Cultural Research

    OpenAIRE

    Riper, Charles Van; Mattson, David J.

    2005-01-01

    Abstract from GoogleBooks: The publication of The Colorado Plateau: Cultural, Biological, and Physical Research in 2004 marked a timely summation of current research in the Four Corners states. This new volume, derived from the seventh Biennial Conference on the Colorado Plateau in 2003, complements the previous book by again focusing on the integration of science into resource management issues. The 32 chapters range in content from measuring human impacts on cultural resources, through graz...

  8. Colorado River cutthroat habitat resistance and resilience to climate change

    OpenAIRE

    Olsen, Kate

    2013-01-01

    Colorado River cutthroat trout, Oncorhyncus clarki pleuriticus , occupy less than 12% of their historic range. Restoration and conservation of this species are currently under way across the upper Colorado River basin, but guidance to inform management decisions related to the impacts of climate change on cutthroat is lacking. Shifts in the thermal distribution of freshwater fish have been documented, and will continue to occur as cold water habitat is threatened by warming water temperatures...

  9. Technique and palette of XIIIth century painting in the monastery of Mileseva

    Science.gov (United States)

    Zorba, T.; Pavlidou, E.; Stanojlovic, M.; Bikiaris, D.; Paraskevopoulos, K. M.; Nikolic, V.; Nikolic, P. M.

    2006-06-01

    The monastery of Mileseva is one of the most important Serbian spiritual centers, and being a Romanesque type building, is nowadays mainly known for its frescoes. The first group of frescoes were produced in the 1230s. In the second half of the sixteenth century, the church was repainted with a new layer of frescoes of which only fragments have survived. These frescoes were damaged in a fire, but they happened to save (acting as a protective layer) the earlier and more valuable paintings from the thirteenth century. The fresco examined in the present study is in the southern part of the area under the dome and belongs to the XIII century fresco. The materials and techniques used for church iconography were determined by means of several micro-analytical techniques. The strong presence of the characteristic peaks of calcite (1407, 872 cm-1), in all FTIR spectra obtained from the substrate, as well as from painted layers confirms the use of the fresco technique for the construction of the wall painting. The combination of FTIR micro-spectroscopy and SEM-EDS elemental microanalysis revealed the existence of lapis lazuli in blue colours and green earth (celadonite) in green colours. In a sample taken from an angel halo, three different layers were found. With SEM-EDS elemental microanalysis it was verified that the first is a metallic layer of thickness 10 12 μm containing pure silver, while the third (2 3 μm) is gold. As was found by FTIR spectra animal glue was used to stick gold on the silver surface. The method of occurrence of the first and thicker silver sheets is still a puzzle, and we believe that it was applied from the beginning in the hagiography and then covered by the gold sheet for aesthetic reasons.

  10. Silver nanoparticles from silver halide photography to plasmonics

    CERN Document Server

    Tani, Tadaaki

    2015-01-01

    This book provides systematic knowledge and ideas on nanoparticles of Ag and related materials. While Ag and metal nanoparticles are essential for plasmonics, silver halide (AgX) photography relies to a great extent on nanoparticles of Ag and AgX which have the same crystal structure and have been studied extensively for many years. This book has been written to combine the knowledge of nanoparticles of Ag and related materials in plasmonics and AgX photography in order to provide new ideas for metal nanoparticles in plasmonics. Chapters 1–3 of this book describe the structure and formation of nanoparticles of Ag and related materials. Systematic descriptions of the structure and preparation of Ag, Au, and noble-metal nanoparticles for plasmonics are followed by and related to those of nanoparticles of Ag and AgX in AgX photography. Knowledge of the structure and preparation of Ag and AgX nanoparticles in photography covers nanoparticles with widely varying sizes, shapes, and structures, and formation proce...

  11. Silver diffusion and isotope effect in silver rubidium iodide

    International Nuclear Information System (INIS)

    The diffusion coefficient of silver in RbAg4I5 was measured in both superionic phases using radiotracer Ag-110m and serial sectioning with a low temperature sectioning apparatus. The activation energies for diffusion in alpha-RbAg4I5 and beta-RbAg4I5, respectively, are 0.11 +- 0.01 eV and 0.20 +- 0.04 eV. An isotope effect for diffusion was also measured in both superionic phases. Ag-105 and Ag-110m radioisotopes were used with gamma spectroscopy and energy discrimination. The effect is small, with no significant temperature variation, with the value at 3330K being 0.12 +- 0.01. The second-order phase transition at 2080K has a small effect, if any, on the magnitude of the effect. The data suggest that a highly cooperative transport mechanism is responsible for the unusually high values of both the conductivity and diffusion coefficient. Although it is not possible to deduce the particular mechanism involved, theories inolving ionic polarons, or cooperative motion, such as crowdions or solitons, seem consistent with the observed results

  12. Separation of silver from silver-manganese ore with cellulose as reductant

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-yun; TIAN Xue-da; ZHANG Dong-fang

    2006-01-01

    The silver in some silver-manganese ore with a grade of 3.15 × 10-4 was concentrated by a combined beneficiation technique including magnetic separation, flotation, reducing leaching and gravity desliming. The major silver contained in manganese ore as isomorphism was concentrated by magnetic separation, while around 8.50% of the silver individual minerals were separated by flotation. The manganese in the mixed concentrate of both magnetic separation and flotation was dissolved in a reducing leaching, in which some cellulose reductant named CMK was used. Part of the slime contained in leach residue was removed by a laboratory desliming equipment. A silver concentrate with a grade of 4.96 × 10-3 Ag and a recovery of 84.25% were obtained.

  13. Silver-plated carbon nanotubes for silver/conducting polymer composites

    Science.gov (United States)

    Oh, Youngseok; Suh, Daewoo; Kim, Youngjin; Lee, Eungsuek; Mok, Jee Soo; Choi, Jaeboong; Baik, Seunghyun

    2008-12-01

    Carbon nanotubes (CNTs) have advantages as conductive fillers due to their large aspect ratio and excellent conductivity. In this study, a novel silver/conducting polymer composite was developed by the incorporation of silver-plated CNTs. It is important to achieve a homogeneous dispersion of nanotubes and to improve the interfacial bonding to utilize the excellent properties of reinforcements in the matrix material. The homogeneous dispersion of nanotubes was achieved by an acid treatment process, and the interfacial contact was improved by electroless silver plating around nanotubes. The resistivity of the silver/conducting polymer composite was decreased by 83% by the addition of silver-plated single-walled carbon nanotubes. Conductive bumps were also screen-printed to demonstrate the capability of the composite as electrical interconnects for multi-layer printed circuit boards.

  14. Silver-plated carbon nanotubes for silver/conducting polymer composites

    International Nuclear Information System (INIS)

    Carbon nanotubes (CNTs) have advantages as conductive fillers due to their large aspect ratio and excellent conductivity. In this study, a novel silver/conducting polymer composite was developed by the incorporation of silver-plated CNTs. It is important to achieve a homogeneous dispersion of nanotubes and to improve the interfacial bonding to utilize the excellent properties of reinforcements in the matrix material. The homogeneous dispersion of nanotubes was achieved by an acid treatment process, and the interfacial contact was improved by electroless silver plating around nanotubes. The resistivity of the silver/conducting polymer composite was decreased by 83% by the addition of silver-plated single-walled carbon nanotubes. Conductive bumps were also screen-printed to demonstrate the capability of the composite as electrical interconnects for multi-layer printed circuit boards.

  15. Update of the Accounting Surface Along the Lower Colorado River

    Science.gov (United States)

    Wiele, Stephen M.; Leake, Stanley A.; Owen-Joyce, Sandra J.; McGuire, Emmet H.

    2008-01-01

    The accounting-surface method was developed in the 1990s by the U.S. Geological Survey, in cooperation with the Bureau of Reclamation, to identify wells outside the flood plain of the lower Colorado River that yield water that will be replaced by water from the river. This method was needed to identify which wells require an entitlement for diversion of water from the Colorado River and need to be included in accounting for consumptive use of Colorado River water as outlined in the Consolidated Decree of the United States Supreme Court in Arizona v. California. The method is based on the concept of a river aquifer and an accounting surface within the river aquifer. The study area includes the valley adjacent to the lower Colorado River and parts of some adjacent valleys in Arizona, California, Nevada, and Utah and extends from the east end of Lake Mead south to the southerly international boundary with Mexico. Contours for the original accounting surface were hand drawn based on the shape of the aquifer, water-surface elevations in the Colorado River and drainage ditches, and hydrologic judgment. This report documents an update of the original accounting surface based on updated water-surface elevations in the Colorado River and drainage ditches and the use of simple, physically based ground-water flow models to calculate the accounting surface in four areas adjacent to the free-flowing river.

  16. The Anti-American Century?*

    OpenAIRE

    Krastev, Ivan

    2013-01-01

    The twentieth century was “the American century.” championing democracy and capitalism, the United States won the cold War and emerged as the only global superpower— not only in military, but also in economic, technological, and even cultural terms. The widening currency of the English language and the continued desire of millions around the world to emigrate to the united States underlined the reality of U.S. predominance. The future, it was said, looked like a country, and that country was ...

  17. Four Centuries of Return Predictability

    OpenAIRE

    Benjamin Golez; Peter Koudijs

    2014-01-01

    We analyze four centuries of stock prices and dividends in the Dutch, English, and U.S. market. With the exception of the post-1945 period, the dividend-to-price ratio is stationary and predicts returns throughout all four centuries. “Excess volatility” is thus a pervasive feature of financial markets. The dividend-to-price ratio also predicts dividend growth rates in all but the most recent period. Cash-flows were therefore much more important for price movements before 1945, and the dominan...

  18. A Century of Environmental Legislation

    DEFF Research Database (Denmark)

    Kaiser, Brooks; Cain, Louis

    2014-01-01

    We examine federal intervention in natural resource use by analyzing roll-call votes over the past century. These votes involved decisions regarding public land that reallocated the returns to users by changing the asset’s physical character or its usage rights. We suggest that long term conseque......We examine federal intervention in natural resource use by analyzing roll-call votes over the past century. These votes involved decisions regarding public land that reallocated the returns to users by changing the asset’s physical character or its usage rights. We suggest that long term...

  19. Glass frits coated with silver nanoparticles for silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yingfen, E-mail: lyf350857423@163.com; Gan, Weiping; Zhou, Jian; Li, Biyuan

    2015-06-30

    Graphical abstract: - Highlights: • Silver-coated glass frits for solar cells were prepared by electroless plating. • Gum Arabic was used as the activating agent of glass frits. • Silver-coated glass frits can improve the photovoltaic performances of solar cells. - Abstract: Glass frits coated with silver nanoparticles were prepared by electroless plating. Gum Arabic (GA) was used as the activating agent of glass frits without the assistance of stannous chloride or palladium chloride. The silver-coated glass frits prepared with different GA dosages were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The characterization results indicated that silver-coated glass frits had the structures of both glass and silver. Spherical silver nanoparticles were distributed on the glass frits evenly. The density and particle size of silver nanoparticles on the glass frits can be controlled by adjusting the GA dosage. The silver-coated glass frits were applied to silver pastes to act as both the densification promoter and silver crystallite formation aid in the silver electrodes. The prepared silver-coated glass frits can improve the photovoltaic performances of solar cells.

  20. Glass frits coated with silver nanoparticles for silicon solar cells

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Silver-coated glass frits for solar cells were prepared by electroless plating. • Gum Arabic was used as the activating agent of glass frits. • Silver-coated glass frits can improve the photovoltaic performances of solar cells. - Abstract: Glass frits coated with silver nanoparticles were prepared by electroless plating. Gum Arabic (GA) was used as the activating agent of glass frits without the assistance of stannous chloride or palladium chloride. The silver-coated glass frits prepared with different GA dosages were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The characterization results indicated that silver-coated glass frits had the structures of both glass and silver. Spherical silver nanoparticles were distributed on the glass frits evenly. The density and particle size of silver nanoparticles on the glass frits can be controlled by adjusting the GA dosage. The silver-coated glass frits were applied to silver pastes to act as both the densification promoter and silver crystallite formation aid in the silver electrodes. The prepared silver-coated glass frits can improve the photovoltaic performances of solar cells

  1. Silver nanoclusters emitting weak NIR fluorescence biomineralized by BSA

    Science.gov (United States)

    Li, Baoshun; Li, Jianjun; Zhao, Junwu

    2015-01-01

    Noble metal (e.g., gold and silver) nanomaterials possess unique physical and chemical properties. In present work, silver nanoclusters (also known as silver quantum clusters or silver quantum dots) were synthesized by bovine serum albumin (BSA) biomineralization. The synthesized silver nanoclusters were characterized by UV-VIS absorption spectroscopy, fluorescence spectroscopy, upconversion emission spectroscopy, TEM, HRTEM and FTIR spectroscopy. TEM results showed that the average size of the silver nanoclusters was 2.23 nm. Fluorescence results showed that these silver nanoclusters could emit weak near-infrared (NIR) fluorescence (the central emission wavelength being about 765 nm). And the central excitation wavelength was about 395 nm, in the UV spectral region. These silver nanoclusters showed an extraordinarily large gap (about 370 nm) between the central excitation wavelength and central emission wavelength. In addition, it was found that these silver nanoclusters possess upconversion emission property. Upconversion emission results showed that the upconversion emission spectrum of the silver nanoclusters agreed well with their normal fluorescence emission spectrum. The synthesized silver nanoclusters showed high stability in aqueous solution and it was considered that they might be confined in BSA molecules. It was found that silver nanoclusters might enhance and broaden the absorption of proteins, and the protein absorption peak showed an obvious red shift (being 7 nm) after the formation of silver nanoclusters.

  2. 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.

  3. Economic impact study of the Uranium Mill Tailings Remedial Action Project in Colorado: Colorado State fiscal year 1994. Revision 1

    International Nuclear Information System (INIS)

    The Colorado economic impact study summarizes employment and economic benefits to the state from activities associated with the Uranium Mill Tailings Remedial Action (UMTRA) Project during Colorado state fiscal year 1994 (1 July 1993 through 30 June 1994). To capture employment information, a questionnaire was distributed to subcontractor employees at the active UMTRA Project sites of Grand Junction, Naturita, Gunnison, and Rifle, Colorado. Economic data were requested from each site prime subcontractor, as well as from the Remedial Action Contractor. Information on wages, taxes, and subcontract expenditures in combination with estimates and economic multipliers is used to estimate the dollar economic benefits to Colorado during the state fiscal year. Finally, the fiscal year 1994 estimates are compared to fiscal year 1993 employment and economic information

  4. Economic impact study of the Uranium Mill Tailings Remedial Action Project in Colorado: Colorado State fiscal year 1994. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    1994-12-01

    The Colorado economic impact study summarizes employment and economic benefits to the state from activities associated with the Uranium Mill Tailings Remedial Action (UMTRA) Project during Colorado state fiscal year 1994 (1 July 1993 through 30 June 1994). To capture employment information, a questionnaire was distributed to subcontractor employees at the active UMTRA Project sites of Grand Junction, Naturita, Gunnison, and Rifle, Colorado. Economic data were requested from each site prime subcontractor, as well as from the Remedial Action Contractor. Information on wages, taxes, and subcontract expenditures in combination with estimates and economic multipliers is used to estimate the dollar economic benefits to Colorado during the state fiscal year. Finally, the fiscal year 1994 estimates are compared to fiscal year 1993 employment and economic information.

  5. Colorado River Wildlife Management Area (Colorado and Gunnison River Easements) [Land Status Map: Sheet 2 of 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This map was produced by the Division of Realty to depict landownership at Colorado River Wildlife Management Area. It was generated from rectified aerial...

  6. Archaeometrical studies on medieval silver coins at the Bucharest Tandem Accelerator

    International Nuclear Information System (INIS)

    The analysis of archaeological objects requires simultaneously, non-destructive, fast, versatile, sensitive and multielemental methods. The purpose of our work is to help Romanian curators to identify objects' provenance (workshops, technologies, mines) and to establish commercial, military and political connections. Medieval Moldavian (XIV-XVI Centuries) silver coins (groschen) were studied to determine the evolution of the coinage (debasement, metal sources, minting technologies). For these coins, two methods were used: 3 MeV protons PIXE (Proton Induced X-ray Emission) and 241 Am source based XRF (X-Ray Fluorescence). XRF was used to determine the heavier elements concentrations. Comparing the trace elements results (Bi, Pb, Zn, Au, Sb) obtained on these samples with the ones on coins from the neighboring countries (Hungary, Poland, Tatar Khanate, Bohemia) we concluded that a lot of Moldavian emissions were made by melting foreign coins, probably obtained as customs taxes. For some coins, the Hg presence is an indication of the use of local silver ores to manufacture local money. The relationship between the silver content of the coins and the military conflicts during various periods is discussed. (authors)

  7. X-Ray Fluorescence and Laser-Induced Breakdown Spectroscopy analysis of Roman silver denarii

    Energy Technology Data Exchange (ETDEWEB)

    Pardini, L. [Istituto di Chimica dei Composti Organometallici del CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); El Hassan, A. [National Institute for Laser- Enhanced Sciences (NILES), Cairo University Giza (Egypt); Ferretti, M. [Istituto per le Tecnologie Applicate ai Beni Culturali, Area della Ricerca del CNR di Montelibretti Roma (Italy); Foresta, A.; Legnaioli, S.; Lorenzetti, G. [Istituto di Chimica dei Composti Organometallici del CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Nebbia, E. [Universita degli Studi di Torino (Italy); Catalli, F. [Monetiere di Firenze, Museo Archeologico Nazionale Firenze (Italy); Harith, M.A. [National Institute for Laser- Enhanced Sciences (NILES), Cairo University Giza (Egypt); Diaz Pace, D. [Institute of Physics ' Arroyo Seco' , Faculty of Science, Tandil (Argentina); Anabitarte Garcia, F. [Photonics Engineering Group, University of Cantabria, Santander (Spain); Scuotto, M. [Dipartimento di Scienze Archeologiche, Via Galvani 1, 56126 Pisa (Italy); Palleschi, V., E-mail: vincenzo.palleschi@cnr.it [Istituto di Chimica dei Composti Organometallici del CNR, Research Area of Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Dipartimento di Scienze Archeologiche, Via Galvani 1, 56126 Pisa (Italy)

    2012-08-15

    In this paper we present the results of a study performed on a large collection of silver Roman republican denarii, encompassing about two centuries of history. The joint use of Laser-Induced Breakdown Spectroscopy (LIBS) and X-Ray Fluorescence (XRF) spectroscopy allowed for an accurate determination of the coins' elemental composition; the measurements, performed mostly in situ at the 'Monetiere' in Florence, revealed a striking connection between the 'quality' of the silver alloy and some crucial contemporary events. This finding was used to classify a group of denarii whose dating was otherwise impossible. The comparison with other contemporary denarii disproves a recent theory on the origin of the so called 'serrated' denarii (denarii showing notched chisel marks on the edge of the coin). - Highlights: Black-Right-Pointing-Pointer We studied a large collection of Roman republican silver denarii. Black-Right-Pointing-Pointer XRF and LIBS allowed to determine the precious metal content of the coins. Black-Right-Pointing-Pointer A correlation of the 'quality' of the alloy with some contemporary events was found. Black-Right-Pointing-Pointer The study allowed to controvert a recent theory on the so called 'serrated' denarii.

  8. [The dilatation of auditive tube (Bougirage tubaire) by dilators in XIX century].

    Science.gov (United States)

    Kierzek, Andrzej

    2006-01-01

    The treatment of auditiory tube chronic catarrh in XIX century by pharmagological drugs, by special apparatuses of surprising technical sophistication, by electrisation and faradisation is discussed first of all. The dilatation of auditory tube by dilators was the diagnostical and therapeutical methods, especially preferenced by Victor Urbantschitsch, Hermann Schwartze, Jean P. Bonnafonte, Albert Calmettes and Bronisław Taczanowski, Teodor Heiman and Samuel Meyerson. The dilators were building of celluloid, whale-bone, silver and were absorbed by argentum nitrate, vaseline. The technique, difficulties and effects of dilatation are described in more detail. The complications of this operation is presented finally. PMID:17131853

  9. Silver and Co-Ni sulphoarsenides from the Kongsberg silver deposit, Norway

    Science.gov (United States)

    Kullerud, Kåre; Kotková, Jana; Škoda, Radek

    2015-04-01

    The historical silver mines at Kongsberg, Norway, are world-famous for spectacular samples of thread silver exhibited at numerous mineralogical museums. More than 100 minerals have been reported from the deposit, including native elements (Ag, Au, As, Cu, S, C), sulphides, sulphosalts, selenides, arsenides, carbonates, sulphates, arsenates and halides, in addition to a range of silicate minerals (Neumann, 1944; Johnsen, 1986, 1987; Bancroft et al., 2001). However, documentation of the minerals using state-of-the-art methods such as electron microprobe, with implications for the genesis of the deposit, is largely missing. In our contribution, we present new data on the compositional variations of silver and sulphoarsenides from the silver deposit. Most of the ore minerals studied here occur in calcite veins in the hosting gneiss. For some samples, however, fluorite is the dominating vein mineral associated with the ore minerals. Mineral textures show that native silver formed during at least two separate stages. The earliest generation of native silver is typically represented by euhedral to subhedral crystals, up to 1 mm long. These crystals frequently contain rounded inclusions of acanthite, chalcopyrite and polybasite, and they are commonly rimmed by a zone consisting of Co-Ni-Fe bearing sulphoarsenides. The later generation of native silver occurs as fracture fillings, often enclosing the earlier Ag generation with its rim of sulphoarsenides. Native silver shows significant variations in Hg, Au and Sb contents. Concentrations of up to 20 wt% Hg and up to 2.7 wt% Sb in silver have been measured during the present study. Dyscrasite and allargentum have also been observed in association with native silver. Neumann (1944) reported auriferous silver with up to 50 % Au. The sulphoarsenides rimming the crystals of the first silver generation vary in composition along the cobaltite-gersdorffite series with approximate limiting compositions Ni0.8Fe0.2AsS and Co0.51Ni0

  10. Colorado Better Buildings Project Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Strife, Susie; Yancey, Lea

    2013-12-30

    The Colorado Better Buildings project intended to bring new and existing energy efficiency model programs to market with regional collaboration and funding partnerships. The goals for Boulder County and its program partners were to advance energy efficiency investments, stimulate economic growth in Colorado and advance the state’s energy independence. Collectively, three counties set out to complete 9,025 energy efficiency upgrades in 2.5 years and they succeeded in doing so. Energy efficiency upgrades have been completed in more than 11,000 homes and businesses in these communities. Boulder County and its partners received a $25 million BetterBuildings grant from the U.S. Department of Energy under the American Recovery and Reinvestment Act in the summer of 2010. This was also known as the Energy Efficiency and Conservation Block Grants program. With this funding, Boulder County, the City and County of Denver, and Garfield County set out to design programs for the residential and commercial sectors to overcome key barriers in the energy upgrade process. Since January 2011, these communities have paired homeowners and business owners with an Energy Advisor – an expert to help move from assessment to upgrade with minimal hassle. Pairing this step-by-step assistance with financing incentives has effectively addressed many key barriers, resulting in energy efficiency improvements and happy customers. An expert energy advisor guides the building owner through every step of the process, coordinating the energy assessment, interpreting results for a customized action plan, providing a list of contractors, and finding and applying for all available rebates and low-interest loans. In addition to the expert advising and financial incentives, the programs also included elements of social marketing, technical assistance, workforce development and contractor trainings, project monitoring and verification, and a cloud-based customer data system to coordinate among field

  11. Transparent conducting silver nanowire networks

    CERN Document Server

    van de Groep, Jorik; Polman, Albert; 10.1021/nl301045a

    2013-01-01

    We present a transparent conducting electrode composed of a periodic two-dimensional network of silver nanowires. Networks of Ag nanowires are made with wire diameters of 45-110 nm and pitch of 500, 700 and 1000 nm. Anomalous optical transmission is observed, with an averaged transmission up to 91% for the best transmitting network and sheet resistances as low as 6.5 {\\Omega}/sq for the best conducting network. Our most dilute networks show lower sheet resistance and higher optical transmittance than an 80 nm thick layer of ITO sputtered on glass. By comparing measurements and simulations we identify four distinct physical phenomena that govern the transmission of light through the networks: all related to the excitation of localized surface plasmons and surface plasmon polaritons on the wires. The insights given in this paper provide the key guidelines for designing high-transmittance and low-resistance nanowire electrodes for optoelectronic devices, including thin-film solar cells. For these latter, we disc...

  12. Silver Nanoparticles and Mitochondrial Interaction

    Directory of Open Access Journals (Sweden)

    Eriberto Bressan

    2013-01-01

    Full Text Available Nanotechnology has gone through a period of rapid growth, thus leading to the constant increase in the application of engineered nanomaterials in daily life. Several different types of nanoparticles have been engineered to be employed in a wide array of applications due to their high surface to volume ratio that leads to unique physical and chemical properties. So far, silver nanoparticles (AgNps have been used in many more different medical devices than any other nanomaterial, mainly due to their antimicrobial properties. Despite the promising advantages posed by using AgNps in medical applications, the possible health effects associated with the inevitable human exposure to AgNps have raised concerns as to their use since a clear understanding of their specific interaction with biological systems has not been attained yet. In light of such consideration, aim of the present work is the morphological analysis of the intracellular behavior of AgNps with a diameter of 10 nm, with a special attention to their interaction with mitochondria.

  13. In vitro percutaneous penetration and characterization of silver from silver-containing textiles

    Directory of Open Access Journals (Sweden)

    Bianco C

    2015-03-01

    Full Text Available Carlotta Bianco,1 Sanja Kezic,2 Matteo Crosera,1 Vesna Svetličić,3 Suzana Šegota,3 Giovanni Maina,4 Canzio Romano,5 Francesca Larese,6,7 Gianpiero Adami11Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy; 2Academic Medical Center, Coronel Institute, University of Amsterdam, Amsterdam, the Netherlands; 3Laboratory for Bioelectrochemistry and Surface Imaging, Division for Marine and Environmental Research, Ruder Boškovic Institute, Zagreb, Croatia; 4Department of Clinical and Biological Sciences, University of Turin, Turin, Italy; 5Department of Public and Pediatric Health Sciences, University of Turin, Turin, Italy; 6Unit of Occupational Medicine, University of Trieste, Trieste, Italy; 7Department of Medical Sciences, University of Trieste, Trieste, ItalyAbstract: The objective of this study was to determine the in vitro percutaneous penetration of silver and characterize the silver species released from textiles in different layers of full thickness human skin. For this purpose, two different wound dressings and a garment soaked in artificial sweat were placed in the donor compartments of Franz cells for 24 hours. The concentration of silver in the donor phase and in the skin was determined by an electrothermal atomic absorption spectrometer (ET-AAS and by inductively coupled plasma mass spectrometer (ICP-MS. The characterization of silver species in the textiles and in the skin layers was made by scanning electron microscopy with integrated energy dispersive X-ray spectroscopy (SEM-EDX. Additionally, the size distribution of silver nanoparticles in the textiles was performed by atomic force microscopy (AFM. On the surface of all investigated materials, silver nanoparticles of different size and morphology were found. Released silver concentrations in the soaking solutions (ie, exposure concentration ranged from 0.7 to 4.7 µg/mL (0.6–4.0 µg/cm2, fitting the bactericidal range. Silver and silver

  14. Sintered silver joints via controlled topography of electronic packaging subcomponents

    Science.gov (United States)

    Wereszczak, Andrew A.

    2014-09-02

    Disclosed are sintered silver bonded electronic package subcomponents and methods for making the same. Embodiments of the sintered silver bonded EPSs include topography modification of one or more metal surfaces of semiconductor devices bonded together by the sintered silver joint. The sintered silver bonded EPSs include a first semiconductor device having a first metal surface, the first metal surface having a modified topography that has been chemically etched, grit blasted, uniaxial ground and/or grid sliced connected to a second semiconductor device which may also include a first metal surface with a modified topography, a silver plating layer on the first metal surface of the first semiconductor device and a silver plating layer on the first metal surface of the second semiconductor device and a sintered silver joint between the silver plating layers of the first and second semiconductor devices which bonds the first semiconductor device to the second semiconductor device.

  15. Puente Río Colorado - Costa Rica

    Directory of Open Access Journals (Sweden)

    Kulka, F.

    1973-03-01

    Full Text Available The Colorado River bridge is located in a 95 m deep canyon, with a 122 m span. To choose the type of bridge, it has been endeavoured to use the largest possible number of national building materials which, together with the difficulty of reaching the site, meant that a series of classical solutions had to be rejected. That of an arch bridge was adopted, with a reversed support on prestressed cables, on which the road passes. The system is based on the hanging bridge principle, but with the rolling track resting on the cables, instead of hanging from them. There is a first cover, made up of prefabricated components, on the cables, which strengthens the bridge's stability. This cover supports three portal-columns, the pillars of the final roadway. The cables were prestressed from the heads of the two sloping pillars. The two side spans were designed with prefabricated T girders.El puente Río Colorado está situado en un cañón de 95 m de profundidad, salvando una luz de 122 m. Para la elección del tipo de puente se ha procurado emplear el mayor número posible de materiales de construcción nacionales, lo que, unido a la dificultad de acceso a la obra, hizo que se rechazaran una serie de soluciones clásicas. Se adoptó la de un puente-arco con un soporte invertido sobre cables pretensados, encima del cual descansa la calzada. El sistema está basado en los principios del puente colgante, pero apoyando el camino de rodadura en los cables, en lugar de colgarlo de ellos. Sobre los cables existe una primera cubierta, integrada por elementos prefabricados, que refuerza la estabilidad del puente. Esta cubierta soporta tres pórticos-columna, pilares de la calzada definitiva. El pretensado de los cables se realizó desde las cabezas de dos pilares inclinados. Los dos vanos laterales se proyectaron con vigas en T prefabricadas.

  16. Approaches to local climate action in Colorado

    Science.gov (United States)

    Huang, Y. D.

    2011-12-01

    Though climate change is a global problem, the impacts are felt on the local scale; it follows that the solutions must come at the local level. Fortunately, many cities and municipalities are implementing climate mitigation (or climate action) policies and programs. However, they face many procedural and institutional barriers to their efforts, such of lack of expertise or data, limited human and financial resources, and lack of community engagement (Krause 2011). To address the first obstacle, thirteen in-depth case studies were done of successful model practices ("best practices") of climate action programs carried out by various cities, counties, and organizations in Colorado, and one outside Colorado, and developed into "how-to guides" for other municipalities to use. Research was conducted by reading documents (e.g. annual reports, community guides, city websites), email correspondence with program managers and city officials, and via phone interviews. The information gathered was then compiled into a series of reports containing a narrative description of the initiative; an overview of the plan elements (target audience and goals); implementation strategies and any indicators of success to date (e.g. GHG emissions reductions, cost savings); and the adoption or approval process, as well as community engagement efforts and marketing or messaging strategies. The types of programs covered were energy action plans, energy efficiency programs, renewable energy programs, and transportation and land use programs. Between the thirteen case studies, there was a range of approaches to implementing local climate action programs, examined along two dimensions: focus on climate change (whether it was direct/explicit or indirect/implicit) and extent of government authority. This benchmarking exercise affirmed the conventional wisdom propounded by Pitt (2010), that peer pressure (that is, the presence of neighboring jurisdictions with climate initiatives), the level of

  17. A Century of Environmental Legislation

    DEFF Research Database (Denmark)

    Kaiser, Brooks; Cain, Louis P.

    2016-01-01

    natural resource use by analyzing roll call votes over the past century with a Random Utility Model (Manski, 1977) and conclude that economics mattered. So did ideology, but not uniformly. After World War II, the pro-environment vote which had been conservative shifted to being liberal. All these votes...

  18. A century of oil exploration

    International Nuclear Information System (INIS)

    The paper speech of the events and decisions that marked the history of the petroleum in Colombia and of Ecopetrol, from the adventure undertaken by some visionary at the beginning of the century X X, until the changes introduced in 1999

  19. Elementary particle physics and high energy phenomena. [Dept. of Physics, Univ. of Colorado, Boulder, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Barker, A.R.; Cumalat, J.P.; De Alwis, S.P.; DeGrand, T.A.; Ford, W.T.; Mahanthappa, K.T.; Nauenberg, U.; Rankin, P.; Smith, J.G.

    1992-06-01

    Experimental and theoretical high-energy physics programs at the University of Colorado are reported. Areas of concentration include the following: study of the properties of the Z[sup 0] with the SLD detector; fixed-target K-decay experiments; the R D program for the muon system: the SDC detector; high-energy photoproduction of states containing heavy quarks; electron--positron physics with the CLEO II detector at CESR; lattice QCD; and spin models and dynamically triangulated random surfaces. 24 figs., 2 tabs., 117 refs.

  20. 75 FR 66786 - Notice of Invitation To Participate; Exploration for Coal in Colorado License Application COC-74447

    Science.gov (United States)

    2010-10-29

    ... State Office, 2850 Youngfield Street, Lakewood, Colorado 80215, and the BLM, Little Snake Field Office... Director, in writing, at the BLM Colorado State Office, 2850 Youngfield Street, Lakewood, Colorado...

  1. 75 FR 44983 - Notice of Invitation To Participate; Exploration for Coal in Colorado; License Application COC-74235

    Science.gov (United States)

    2010-07-30

    ... Office, 2850 Youngfield Street, Lakewood, Colorado 80215 and the BLM, Uncompahgre Field Office, 2505 S..., in writing, at the BLM Colorado State Office, 2850 Youngfield Street, Lakewood, Colorado 80215...

  2. In situ SU-8 silver nanocomposites

    Directory of Open Access Journals (Sweden)

    Søren V. Fischer

    2015-07-01

    Full Text Available Nanocomposite materials containing metal nanoparticles are of considerable interest in photonics and optoelectronics applications. However, device fabrication of such materials always encounters the challenge of incorporation of preformed nanoparticles into photoresist materials. As a solution to this problem, an easy new method of fabricating silver nanocomposites by an in situ reduction of precursors within the epoxy-based photoresist SU-8 has been developed. AgNO3 dissolved in acetonitrile and mixed with the epoxy-based photoresist SU-8 forms silver nanoparticles primarily during the pre- and post-exposure soft bake steps at 95 °C. A further high-temperature treatment at 300 °C resulted in the formation of densely homogeneously distributed silver nanoparticles in the photoresist matrix. No particle growth or agglomeration of nanoparticles is observed at this point. The reported new in situ silver nanocomposite materials can be spin coated as homogeneous thin films and structured by using UV lithography. A resolution of 5 µm is achieved in the lithographic process. The UV exposure time is found to be independent of the nanoparticle concentration. The fabricated silver nanocomposites exhibit high plasmonic responses suitable for the development of new optoelectronic and optical sensing devices.

  3. Cytotoxicity and genotoxicity of biogenic silver nanoparticles

    Science.gov (United States)

    Lima, R.; Feitosa, L. O.; Ballottin, D.; Marcato, P. D.; Tasic, L.; Durán, N.

    2013-04-01

    Biogenic silver nanoparticles with 40.3 ± 3.5 nm size and negative surface charge (- 40 mV) were prepared with Fusarium oxysporum. The cytotoxicity of 3T3 cell and human lymphocyte were studied by a TaliTM image-based cytometer and the genotoxicity through Allium cepa and comet assay. The results of BioAg-w (washed) and BioAg-nw (unwashed) biogenic silver nanoparticles showed cytotoxicity exceeding 50 μg/mL with no significant differences of response in 5 and 10 μg/mL regarding viability. Results of genotoxicity at concentrations 5.0 and 10.0 ug/mL show some response, but at concentrations 0.5 and 1.0 μg/mL the washed and unwashed silver nanoparticles did not present any effect. This in an important result since in tests with different bacteria species and strains, including resistant, MIC (minimal inhibitory concentration) had good answers at concentrations less than 1.9 μg/mL. This work concludes that biogenic silver nanoparticles may be a promising option for antimicrobial use in the range where no cyto or genotoxic effect were observed. Furthermore, human cells were found to have a greater resistance to the toxic effects of silver nanoparticles in comparison with other cells.

  4. Silver superlens using antisymmetric surface plasmon modes.

    Science.gov (United States)

    Lee, Wook-Jae; Kim, Jae-Eun; Park, Hae Yong; Lee, Myung-Hyun

    2010-03-15

    Silver lenses having super-resolution are analyzed in terms of antisymmetric modes of surface plasmon which have the ability to amplify evanescent waves in UV region. Antisymmetric surface plasmon modes excited by subwavelength grating enhances the resolution and contrast of silver superlens. By using a 20 nm-thick silver superlens, the half-pitch resolution of approximately lambda(0)/8 can be achieved with good contrast at a free space wavelength of 435 nm. The resolution of silver superlens can also be improved using shorter illumination wavelength. We show that the thinner the lens, the better the imaging ability of the silver superlens due to the excitation of antisymmetric surface plasmon modes of higher propagation wave vectors. The thickness of lens is varied from 20 to 40 nm in a three layer system, SiO(2)-Ag-SiO(2). Obtained results illustrate that practical application for patterning periodic structures with good contrast and penetration depth can be achieved by using antisymmetric surface plasmon modes. PMID:20389562

  5. Characterization of antibacterial silver coated yarns.

    Science.gov (United States)

    Pollini, M; Russo, M; Licciulli, A; Sannino, A; Maffezzoli, A

    2009-11-01

    Surface treatments of textile fibers and fabrics significantly increase their performances for specific biomedical applications. Nowadays, silver is the most used antibacterial agent with a number of advantages. Among them, it is worth to note the high degree of biocompatibility, an excellent resistance to sterilization conditions, antibacterial properties with respect to different bacteria associated with a long-term of antibacterial efficiency. However, there are only a few antibacterial fibres available, mainly synthetic with high production cost and limited effectiveness. Cotton yarns with antimicrobial properties are most suitable for wound healing applications and other medical treatments thanks to their excellent moisture absorbance while synthetic based fibres are most suitable for industrial applications such as automotive tapestry and air filters. The silver-coated fibers were developed applying an innovative and low cost silver deposition technique for natural and synthetic fibers or yarns. The structure and morphology of the silver nanoclusters on the fibers was observed by scanning electron microscopy (SEM), atomic force microscopy analysis (AFM) and XRD analysis, and quantitatively confirmed by thermogravimetric analysis (TGA) measurements. Good silver coating stability has been confirmed performing several industrial washing. Antimicrobial tests with Escherichia coli were performed. PMID:19526328

  6. The Antimicrobial Action of Silver Halides in Calcium Phosphate

    OpenAIRE

    Kalniņa, D; Gross, K; Onufrijevs, P.; Daukšta, E; Nikolajeva, V; Stankeviciute, Z; Kareiva, A.

    2015-01-01

    Silver halides represent a yet unexplored avenue for imparting antimicrobial activity to calcium phosphates. Negtively charged silver halide colloids (AgI, AgBr and AgCl) were added to synthesized amorphous calcium phosphate. Concurrent melting of silver halides and crystallization to carbonated apatite at 700 oC increased the silver halide surface area available to bacteria and formed a lower solubility apatite. The effect of the matrix solubility on antimicrobial response could ...

  7. SURFACE ENHANCED RAMAN SPECTRA FROM OXYGEN ON SILVER

    OpenAIRE

    Pettenkofer, C.; Pockrand, I.; Otto, A.

    1983-01-01

    Silver is an important catalyst for the epoxidation of ethylene and the production of formaldehyd from methanol. It is not yet known with certainty which form of adsorbed oxygen on silver is the catalytically active one. Therefore we have started to study the adsorption of oxygen on silver films by Raman spectroscopy. From previous investigations, especially from UPS work /1/, we know that at low exposures of ground state molecular oxygen, oxygen sticks on evaporated silver films only at defe...

  8. Nanoscale characterization of thin immersion silver coatings on copper substrates

    OpenAIRE

    Török, T. I.; Csik, A.; Hakl, J.; Vad, K.; KÖvÉr, L.; Tóth, J.; Mészáros, S.; Kun, É.; Sós, D.

    2015-01-01

    Microelectronic-grade copper foils were immersion silver plated in a home-made non-cyanide alkaline silver nitrate - thiosulfate solution and in two commercially available industrial baths via contact reductive precipitation. The concentration depth profiles of the freshly deposited silver layers were afterwards analyzed at nanoscale resolution by means of Secondary Neutral Mass Spectrometry (SNMS) and Glow Discharge Optical Emission Spectroscopy (GDOES). The thickness of deposited silver lay...

  9. Morphology and mechanical properties of antimicrobial polyamide/silver composites

    OpenAIRE

    Radheshkumar, C.; Münstedt, Helmut

    2005-01-01

    Silver filled antimicrobial polymers were produced from composites comprising polyamide and elementary silver powder possessing various specific surface area (SSA) by melt compounding. Different concentrations (2%, 4% and 8%) of the silver powder were incorporated in the polyamide to investigate the effect of silver loading on the mechanical properties. As the water uptake imparts antimicrobial properties, the influence of the diffused water on the mechanical properties of the compos...

  10. Comparison of in vitro toxicity of silver ions and silver nanoparticles on human hepatoma cells.

    Science.gov (United States)

    Vrček, Ivana Vinković; Žuntar, Irena; Petlevski, Roberta; Pavičić, Ivan; Dutour Sikirić, Maja; Ćurlin, Marija; Goessler, Walter

    2016-06-01

    Scientific information on the potential harmful effects of silver nanoparticles (AgNPs) on human health severely lags behind their exponentially growing applications in consumer products. In assessing the toxic risk of AgNP usage, liver, as a detoxifying organ, is particularly important. The aim of this study was to explore the toxicity mechanisms of nano and ionic forms of silver on human hepatoblastoma (HepG2) cells. The results showed that silver ions and citrate-coated AgNPs reduced cell viability in a dose-dependent manner. The IC50 values of silver ions and citrate-coated AgNPs were 0.5 and 50 mg L(-1) , respectively. The LDH leakage and inhibition of albumin synthesis, along with decreased ALT activity, indicated that treatment with either AgNP or Ag ions resulted in membrane damage and reduced the cell function of human liver cells. Evaluation of oxidative stress markers demonstrating depletion of GSH, increased ROS production, and increased SOD activity, indicated that oxidative stress might contribute to the toxicity effects of nano and ionic forms of silver. The observed toxic effect of AgNP on HepG2 cells was substantially weaker than that caused by ionic silver, while the uptake of nano and ionic forms of silver by HepG2 cells was nearly the same. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 679-692, 2016. PMID:25448069

  11. Inkjet-printed silver conductors using silver nitrate ink and their electrical contacts with conducting polymers

    International Nuclear Information System (INIS)

    This paper presents a low-cost and direct-writing silver metallization process based on drop-on-demand inkjet printing technique. Silver nitrate dissolved in the mixture of water and dimethyl sulfoxide (DMSO) was used as a metal precursor for metallization. The fabricated silver films on polyimide substrate were characterized by means of scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), and electrical measurements. The experimental results show that the inkjet-printed silver tracks have well-defined shapes. The resistivity of the printed silver tracks is around 1.5x10-5 Ω.cm, one order of magnitude larger than that of bulk silver, which is attributed to the porosities as well as the residual impurities. Two conducting polymers (CP), sulfonated polyaniline (SPANi) and poly(ethylene dioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS), were inkjet-printed on the surface of the silver tracks to study electrical properties of the Ag-polymer contacts. The current-voltage measurement results show that the printed Ag-PEDOT/PSS and Ag-SPANi contacts exhibit 'ohmic' behavior

  12. Plasmon enhanced silver quantum cluster fluorescence for biochemical applications

    DEFF Research Database (Denmark)

    Bernard, S.; Kutter, J.P.; Mogensen, Klaus Bo

    2014-01-01

    Fluorescence microscopy of individual silver quantum clusters on the surface of silver nanoparticles reveals strong photoactivated emission under blue light excitation [1-4]. In this work, silver nanoparticles are produced by annealing silver thin films deposited on a glass substrate and silver q...... purposes. It was found, that in presence of a strong nucleophile (such as CN-), silver quantum clusters are dissolved into non-fluorescing AgCN complexes, resulting in a fast and observable decrease of the fluorescent signal.......Fluorescence microscopy of individual silver quantum clusters on the surface of silver nanoparticles reveals strong photoactivated emission under blue light excitation [1-4]. In this work, silver nanoparticles are produced by annealing silver thin films deposited on a glass substrate and silver...... quantum clusters are subsequently synthesized at the surface of the nanoparticles by photoactivation in presence of Ag+ cations in solution. The photogeneration of these silver quantum clusters leads to a great increase in the fluorescent signal. This photoactivated surface can then be used for sensing...

  13. Silver-functionalized carbon nanofiber composite electrodes for ibuprofen detection

    NARCIS (Netherlands)

    Manea, F.; Motoc, S.; Pop, A.; Remes, A.; Schoonman, J.

    2012-01-01

    The aim of this study is to prepare and characterize two types of silver-functionalized carbon nanofiber (CNF) composite electrodes, i.e., silver-decorated CNF-epoxy and silver-modified natural zeolite-CNF-epoxy composite electrodes suitable for ibuprofen detection in aqueous solution. Ag carbon nan

  14. Autocatalytic Patterning with Silver Using Tin(II) Chloride Sensitizer

    Science.gov (United States)

    Mbindyo, Jeremiah K. N.; Anna, Laura J.; Fell, B. Andrew; Patton, David A.

    2011-01-01

    A silver mirror can be deposited on many types of surfaces from the reduction of the silver-diammine complex by a reducing sugar as proposed by Kemp in this "Journal". Three extensions of Kemp's demonstration that highlight the role of SnCl[subscript 2] sensitizer in the deposition of a silver mirror on surfaces are presented. The demonstration…

  15. A New Silver Complex with Ofloxacin – Preliminary Study

    Directory of Open Access Journals (Sweden)

    Rusu Aura

    2016-06-01

    Full Text Available Objective: Silver complexes of antibacterial quinolones have the potential advantage of combining the antibacterial activity of silver and fluoroquinolones. The objective of our study was the preparation and the preliminary physico-chemical characterization of a silver complex with ofloxacin.

  16. Fabrication, characterization, and thermal property evaluation of silver nanofluids

    OpenAIRE

    Noroozi, Monir; Radiman, Shahidan; Zakaria, Azmi; Soltaninejad, Sepideh

    2014-01-01

    Silver nanoparticles were successfully prepared in two different solvents using a microwave heating technique, with various irradiation times. The silver nanoparticles were dispersed in polar liquids (distilled water and ethylene glycol) without any other reducing agent, in the presence of the stabilizer polyvinylpyrrolidone (PVP). The optical properties, thermal properties, and morphology of the synthesized silver particles were characterized using ultraviolet-visible spectroscopy, photopyro...

  17. Preliminary Site Characterization Report, Rulsion Site, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-08-01

    This report is a summary of environmental information gathered during a review of the documents pertaining to Project Rulison and interviews with personnel who worked on the project. Project Rulison was part of Operation Plowshare (a program designed to explore peaceful uses for nuclear devices). The project consisted of detonating a 43-kiloton nuclear device on September 10, 1969, in western Colorado to stimulate natural gas production. Following the detonation, a reentry well was drilled and several gas production tests were conducted. The reentry well was shut-in after the last gas production test and was held in standby condition until the general cleanup was undertaken in 1972. A final cleanup was conducted after the emplacement and testing wells were plugged in 1976. However, some surface radiologic contamination resulted from decontamination of the drilling equipment and fallout from the gas flaring during drilling operations. With the exception of the drilling effluent pond, all surface contamination at the Rulison Site was removed during the cleanup operations. All mudpits and other excavations were backfilled, and both upper and lower drilling pads were leveled and dressed. This report provides information regarding known or suspected areas of contamination, previous cleanup activities, analytical results, a review of the regulatory status, the site`s physical environment, and future recommendations for Project Ruhson. Based on this research, several potential areas of contamination have been identified. These include the drilling effluent pond and mudpits used during drilling operations. In addition, contamination could migrate in the gas horizon.

  18. Colorado longitudinal twin study of reading disability.

    Science.gov (United States)

    Wadsworth, Sally J; DeFries, John C; Olson, Richard K; Willcutt, Erik G

    2007-12-01

    The primary objectives of the present study are to introduce the Colorado Longitudinal Twin Study of Reading Disability, the first longitudinal twin study in which subjects have been specifically selected for having a history of reading difficulties, and to present some initial assessments of the stability of reading performance and cognitive abilities in this sample. Preliminary examination of the test scores of 124 twins with a history of reading difficulties and 154 twins with no history of reading difficulties indicates that over the 5- to 6-year interval between assessments, cognitive and reading performance are highly stable. As a group, those subjects with a history of reading difficulties had substantial deficits relative to control subjects on all measures at initial assessment, and significant deficits remained at follow-up. The stability noted for all cognitive and achievement measures was highest for a composite measure of reading, whose average stability correlation across groups was 0.80. Results of preliminary behavior genetic analyses for this measure indicated that shared genetic influences accounted for 86% and 49% of the phenotypic correlations between the two assessments for twin pairs with and without reading difficulties, respectively. In addition, genetic correlations reached unity for both groups, suggesting that the same genetic influences are manifested at both time points. PMID:18060583

  19. Energy dispersive X-ray fluorescence analysis of ancient coins: The case of Greek silver drachmae from the Emporion site in Spain

    International Nuclear Information System (INIS)

    Greek colonizers arrived at the Iberian Peninsula at the beginning of the sixth century B.C. and founded a small colony known as Emporion in north-east Spain. By the fifth century B.C., this colony became a small polis with a well-organized administrative structure. In this context, the necessity of coinage was a fact and the first coins were minted. Some of these coins were characterized by using energy dispersive X-ray fluorescence equipment. The analytical study focused on the elemental characterization of the coins minted from the fourth century to the first century B.C. and their compositional evolution during this period. The investigation has pointed out a very high fineness of the alloys throughout the time, with an average silver content around 98.32%, and the feasibility of energy dispersive X-ray fluorescence as a screening tool for the characterization of the alloys.

  20. Nanostructural Features of Silver Nanoparticles Powder Synthesized through Concurrent Formation of the Nanosized Particles of Both Starch and Silver

    OpenAIRE

    A. Hebeish; El-Rafie, M. H.; El-Sheikh, M. A.; Mehrez E. El-Naggar

    2013-01-01

    Green innovative strategy was developed to accomplish silver nanoparticles formation of starch-silver nanoparticles (St-AgNPs) in the powder form. Thus, St-AgNPs were synthesized through concurrent formation of the nanosized particles of both starch and silver. The alkali dissolved starch acts as reducing agent for silver ions and as stabilizing agent for the formed AgNPs. The chemical reduction process occurred in water bath under high-speed homogenizer. After completion of the reaction, the...

  1. Silver nanoparticle containing silk fibroin bionanotextiles

    Energy Technology Data Exchange (ETDEWEB)

    Calamak, Semih; Aksoy, Eda Ayse [Hacettepe University, Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy (Turkey); Erdogdu, Ceren; Sagıroglu, Meral [Hacettepe University, Department of Pharmaceutical Microbiology, Faculty of Pharmacy (Turkey); Ulubayram, Kezban, E-mail: ukezban@hacettepe.edu.tr [Hacettepe University, Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy (Turkey)

    2015-02-15

    Development of new generation bionanotextiles is an important growing field, and they have found applications as wound dressings, bandages, tissue scaffolds, etc. In this study, silver nanoparticle (AgNP) containing silk-based bionanotextiles were fabricated by electrospinning, and processing parameters were optimized and discussed in detail. AgNPs were in situ synthesized within fibroin nanofibers by UV reduction of silver ions to metallic silver. The influence of post-treatments via methanol treatment and glutaraldehyde (GA) vapor exhibited changes in the secondary structure of silk. Methanol treatment increased the tensile properties of fibers due to supported crystalline silk structure, while GA vapor promoted amorphous secondary structure. AgNP containing silk fibroin bionanotextiles had strong antibacterial activity against gram-positive Staphylococcus aureus and gram-negative Pseudomonas aeruginosa.

  2. Silver nanoparticle containing silk fibroin bionanotextiles

    International Nuclear Information System (INIS)

    Development of new generation bionanotextiles is an important growing field, and they have found applications as wound dressings, bandages, tissue scaffolds, etc. In this study, silver nanoparticle (AgNP) containing silk-based bionanotextiles were fabricated by electrospinning, and processing parameters were optimized and discussed in detail. AgNPs were in situ synthesized within fibroin nanofibers by UV reduction of silver ions to metallic silver. The influence of post-treatments via methanol treatment and glutaraldehyde (GA) vapor exhibited changes in the secondary structure of silk. Methanol treatment increased the tensile properties of fibers due to supported crystalline silk structure, while GA vapor promoted amorphous secondary structure. AgNP containing silk fibroin bionanotextiles had strong antibacterial activity against gram-positive Staphylococcus aureus and gram-negative Pseudomonas aeruginosa

  3. Hydrogels made from chitosan and silver nitrate.

    Science.gov (United States)

    Kozicki, Marek; Kołodziejczyk, Marek; Szynkowska, Małgorzata; Pawlaczyk, Aleksandra; Leśniewska, Ewa; Matusiak, Aleksandra; Adamus, Agnieszka; Karolczak, Aleksandra

    2016-04-20

    This work describes a gelation of chitosan solution with silver nitrate. Above the critical concentration of chitosan (c*), continuous hydrogels of chitosan-silver can be formed. At lower concentrations, the formation of nano- and micro-hydrogels is discussed. The sol-gel analysis was performed to characterise the hydrogels' swelling properties. Moreover, the following were employed: (i) mechanical testing of hydrogels, (ii) inductively coupled plasma-optical emission spectroscopy (ICP-OES) for the measurement of silver concentration, (iii) scanning electron microscopy (SEM) to examine the morphology of products obtained, and (iv) dynamic light scattering (DLS) and UV-vis spectrophotometry to examine products formed at low concentration of chitosan (c

  4. Roasting of refractory gold and silver concentrate

    International Nuclear Information System (INIS)

    In processing of precious metal ores with high pyrite content, refractory concentrates are obtained, which are difficult to process. A refractory gold and silver concentrate was leached with sodium cyanide. Results show low extraction percentages, being 34 % of gold and 40 % of silver. A roasting method to oxidize the concentrate was used, making it more susceptible to cyanidation, hence a more efficient way to extract precious metals. The variables include roasting temperature and roasting and cyanidation time. In addition, the hot calcine was added to the leaching solution at room temperature to analyze the effect on particle size and recovery. The best results, although not entirely satisfactory (50 % of gold and 61 % of silver) were obtained by roasting the concentrate for 4 h at 600 degree centigrade, followed by cyanidation for 20 h. The lime consumption to raise the pH to about 11.3 was increased markedly to 25 kg/m3. (Author) 11 refs.

  5. Deposition of silver layer on different substrates

    Science.gov (United States)

    Krzemiński, J.; Kiełbasiński, K.; Szałapak, J.; Jakubowska, M.; MłoŻniak, A.; Zwierkowska, E.

    2015-09-01

    The hole process of producing continuous layer with silver nanoparticles is presented in this paper. First the ink preparation and then the spray process is shown and discussed. The silver layers were obtained on sodium glass substrate. Three different ink carriers were considered and the best one has been chosen. Spray coating process was carried out using special spray can. After obtaining sprayed layers the samples were sintered in several temperatures to investigate the lowest suitable sintering temperature. After that layers resistivity were measured. Then the silver layers were cracked to produce breakthrough fracture that was investigated by a scanning electron microscope. In this paper, the authors investigated the spray coating technique as an alternative to electroplating and other techniques, considering layer resistivity, thickness and production process.

  6. In-Situ Silver Acetylide Silver Nitrate Explosive Deposition Measurements Using X-Ray Fluorescence.

    Energy Technology Data Exchange (ETDEWEB)

    Covert, Timothy T.

    2014-09-01

    The Light Initiated High Explosive facility utilized a spray deposited coating of silver acetylide - silver nitrate explosive to impart a mechanical shock into targets of interest. A diagnostic was required to measure the explosive deposition in - situ. An X - ray fluorescence spectrometer was deployed at the facility. A measurement methodology was developed to measure the explosive quantity with sufficient accuracy. Through the use of a tin reference material under the silver based explosive, a field calibration relationship has been developed with a standard deviation of 3.2 % . The effect of the inserted tin material into the experiment configuration has been explored.

  7. Title: Flushed Away: Linking Carbon Storage and Log Jams in Colorado's Front Range

    Science.gov (United States)

    Beckman, N. D.; Wohl, E. E.

    2011-12-01

    Historical documents and recent field studies suggest that resource use within the Colorado Rockies during the past two centuries has reduced the wood loads and frequency of wood jams along most forested streams. Recent research has also shown that streams play a significant role in the sequestration and transport of organic carbon, and wood jams are a key component of storage and biological processing in mountain headwater streams. Log jams tend to slow the transport of carbon and encourage its uptake in the riverine environment and therefore may have effects which extend beyond streams and into the global carbon cycle. The paper aims to quantify the effects of past and present resource management on instream wood loads and logjam frequency along Colorado's Front Range. We hypothesize that more highly impacted reaches (as measured by recent fire, logging, and high flow regulation) will demonstrate lower wood loads, lower jam densities and lower overall volume of stored sediment. In addition, we hypothesize that soils stored behind log jams will have a higher OM and TC content. If these hypothesis hold true, then by implication areas with younger forests and higher impacts will have higher carbon flux and lower return of carbon and nutrients to the surrounding ecosystem. Wood loads and jam frequency are compared based on stream characteristics, forest age, and flow alteration. In addition, sediment samples from reaches with and without log jams are compared based on organic matter (OM) content and Total Carbon (TC) content. Samples taken from behind log jams are compared to samples taken from other backwater areas along a river reach. Preliminary results of the 2010/2011 field seasons indicate that sediment samples taken from log jams (regardless of forest age) have an overall average of 5% OM, as compared to an average of 1% OM in samples taken from non-jam areas. Samples taken from log jams on streams draining old growth forests (more than 250 years since last

  8. Lithium Resources for the 21st Century

    Science.gov (United States)

    Kesler, S.; Gruber, P.; Medina, P.; Keolian, G.; Everson, M. P.; Wallington, T.

    2011-12-01

    Lithium is an important industrial compound and the principal component of high energy-density batteries. Because it is the lightest solid element, these batteries are widely used in consumer electronics and are expected to be the basis for battery electric vehicles (BEVs), hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) for the 21st century. In view of the large incremental demand for lithium that will result from expanded use of various types of EVs, long-term estimates of lithium demand and supply are advisable. For GDP growth rates of 2 to 3% and battery recycling rates of 90 to 100%, total demand for lithium for all markets is expected to be a maximum of 19.6 million tonnes through 2100. This includes 3.2 million tonnes for industrial compounds, 3.6 million tonnes for consumer electronics, and 12.8 million tonnes for EVs. Lithium-bearing mineral deposits that might supply this demand contain an estimated resource of approximately 39 million tonnes, although many of these deposits have not been adequately evaluated. These lithium-bearing mineral deposits are of two main types, non-marine playa-brine deposits and igneous deposits. Playa-brine deposits have the greatest immediate resource potential (estimated at 66% of global resources) and include the Salar de Atacama (Chile), the source of almost half of current world lithium production, as well as Zabuye (China/Tibet) and Hombre Muerto (Argentina). Additional important playa-brine lithium resources include Rincon (Argentina), Qaidam (China), Silver Peak (USA) and Uyuni (Bolivia), which together account for about 35% of the estimated global lithium resource. Information on the size and continuity of brine-bearing aquifers in many of these deposits is limited, and differences in chemical composition of brines from deposit to deposit require different extraction processes and yield different product mixes of lithium, boron, potassium and other elements. Numerous other brines in playas

  9. Silver nanoparticles - Wolves in sheep's clothing?

    DEFF Research Database (Denmark)

    Foldbjerg, Rasmus Bruno; Jiang, Xiumei; Micləuş, Teodora;

    2015-01-01

    Silver nanoparticles (Ag NPs) are one of the most widely utilized engineered nanomaterials (ENMs) in commercial products due to their effective antibacterial activity, high electrical conductivity, and optical properties. Therefore, they have been one of the most intensively investigated...... effects following exposure to Ag NPs, information about the mechanisms for their cytotoxicity and genotoxicity is necessary. The present paper attempts to review the cellular and molecular mechanisms behind Ag NP toxicity. In addition, the role of silver ions in the toxicity of Ag NPs is discussed....

  10. Fluorescent DNA Stabilized Silver Nanoclusters as Biosensors

    Directory of Open Access Journals (Sweden)

    Alfonso Latorre

    2013-01-01

    Full Text Available DNA stabilized fluorescent silver nanoclusters are promising materials, of which fluorescent properties can be exploited to develop sensors. Particularly, the presence of a DNA strand in the structure has promoted the development of gene sensors where one part of the sensor is able to recognize the target gene sequence. Moreover, since oligonucleotides can be designed to have binding properties (aptamers a variety of sensors for proteins and cells have been developed using silver nanoclusters. In this review the applications of this material as sensors of different biomolecules are summarized.

  11. Manufacturing of superconductive silver/ceramic composites

    DEFF Research Database (Denmark)

    Seifi, Behrouz; Bech, Jakob Ilsted; Eriksen, Morten; Skov-Hansen, P; Wang, W.G.; Bay, Niels

    2000-01-01

    copper oxides is inserted into a silver tube and reduced by multi-step drawing. These single-filaments are packed in a new silver tube thus forming a multi-filament containing e.g. 37 single-filaments, which is subsequently reduced by drawing and rolling to tapes approximately 0.2 mm thick by 3 mm wide...... current leading properties of the final superconducting fibres. The present work describes studies on alternative packing geometries and process parameters in the flat rolling operations. The aim is to obtain homogenous filaments with advantageous geometry and good texture while avoiding potential defects...... such as cracks, shear band formation and sausaging....

  12. Gold and Silver Inlaid Bronze Sheep

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

  13. Silver release from coated particle fuel

    International Nuclear Information System (INIS)

    The fission product Ag-110 m released from coated particles can be the dominant source of radioactivity from the core of a high temperature reactor in the early stages of the reactor life and possibly limits the accessability of primary circuit components. It can be shown that silver is retained in oxide fuel by a diffusion process (but not in carbide or carbon-diluted fuel) and that silver is released through all types of pyrocarbon layers. The retention in TRISO particles is variable and seems to be mainly connected with operating temperature and silicon carbide quality. (orig.)

  14. Rockteemaillan suunnittelu ja toteutus Silver Music Barissa

    OpenAIRE

    Hiltunen, Anne

    2006-01-01

    Opinnäytetyön aiheena oli suunnitella ja toteuttaa teemailta nimeltään "Rock'n Roll Forever" Hyvinkään ravintola Hopealyhdyn, Silver Music Bariin Tärkeimpinä osina työhön kuuluivat musiikin valinta, kilpailujen ja juomasekoitusten suunnittelu, teemaillan markkinointi ja sponsorointihankkeet, sekä muut asiakokonaisuudet tehden tapahtumasta kokonaisen. Idea työhön lähti kilpailutilanteen muutoksesta Hyvinkäällä, joka johti hiljaisempiin iltoihin ravintolassa ja vaikutti huomattavasti Silver Mus...

  15. Recovery of silver from CEPOD anolyte solutions

    International Nuclear Information System (INIS)

    The process known as Catalyzed Electrochemical Plutonium Oxide Dissolution (CEPOD) has been shown effective for removing plutonium from a variety of residues and solids. This process involves the electrochemical oxidation of PuO2 (and other Pu species) to (PuO2)2+, and dissolution of the latter species in the anode solution (anolyte). Silver is used to transfer charge from the electrodes to the solid Pu oxide. Ag (1) is oxidized at the anode to Ag(II) and carried by the solution to the plutonium oxide solids, where the silver and oxide undergo a redox reaction that converts Pu(IV) to Pu(VI), and Ag(II) to Ag(I). Other metal ions [such as Ce(IV) and Co(III)] may also be used for this charge transfer, but have been found to be less effective than silver. The same process may be used to destroy various organic materials (such as paper and wood, oil and fuels, and synthetic polymer materials) by complete oxidation to CO2 or H2O, for example. Upon completion of a CEPOD dissolver run, the anolyte may be processed to remove solution species of interest (i.e., Pu), or the anolyte may be recycled, or disposed. Because silver is a Resource Conservation and Recovery Act (RCRA) land ban material, it must be removed from waste streams. Preliminary experiments, completed in FY 1991, demonstrated a simple, effective technique for silver removal from solutions. Ascorbic acid (C6H8O6) Was Used to reduce silver ion to metallic silver, which precipitates from solution. The process was demonstrated effective on a bench scale using samples of actual CEPOD anolyte. Further experiments, in FY 1993, optimized these parameters and demonstrated the effectiveness of the technique on CEPOD anolyte on a larger, process scale (liters of solution). This report describes both the preliminary bench-scale experiments and the more recent process-scale experiments. The results are also compared to electro-deposition, another method of silver ion removal

  16. Revealing text in a complexly rolled silver scroll from Jerash with computed tomography and advanced imaging software

    Science.gov (United States)

    Hoffmann Barfod, Gry; Larsen, John Møller; Lichtenberger, Achim; Raja, Rubina

    2015-12-01

    Throughout Antiquity magical amulets written on papyri, lead and silver were used for apotropaic reasons. While papyri often can be unrolled and deciphered, metal scrolls, usually very thin and tightly rolled up, cannot easily be unrolled without damaging the metal. This leaves us with unreadable results due to the damage done or with the decision not to unroll the scroll. The texts vary greatly and tell us about the cultural environment and local as well as individual practices at a variety of locations across the Mediterranean. Here we present the methodology and the results of the digital unfolding of a silver sheet from Jerash in Jordan from the mid-8th century CE. The scroll was inscribed with 17 lines in presumed pseudo-Arabic as well as some magical signs. The successful unfolding shows that it is possible to digitally unfold complexly folded scrolls, but that it requires a combination of the know-how of the software and linguistic knowledge.

  17. Seventeenth-century indivisibles revisited

    CERN Document Server

    2015-01-01

    The tremendous success of indivisibles methods in geometry in the seventeenth century, responds to a vast project: installation of infinity in mathematics. The pathways by the authors are very diverse, as are the characterizations of indivisibles, but there are significant factors of unity between the various doctrines of indivisible; the permanence of the language used by all authors is the strongest sign. These efforts do not lead to the stabilization of a mathematical theory (with principles or axioms, theorems respecting these first statements, followed by applications to a set of geometric situations), one must nevertheless admire the magnitude of the results obtained by these methods and highlights the rich relationships between them and integral calculus. The present book aims to be exhaustive since it analyzes the works of all major inventors of methods of indivisibles during the seventeenth century, from Kepler to Leibniz. It takes into account the rich existing literature usually devoted to a singl...

  18. PHYTOSYNTHESIS OF SILVER NANOPARTICLES USING MEDICINAL AND DYE YIELDING PLANT OF BIXA ORELLANA L. LEAF EXTRACT

    OpenAIRE

    M. Thilagam; A. Tamilselvi; B. Chandrasekeran; Rose, C.

    2013-01-01

    Here in, we report an environmentally friendly approach to synthesize silver nanoparticles. The bio active compounds found in plants induce the reduction of silver ions from silver nitrate to silver nanoparticles. We report the synthesis of silver nanoparticles and also phytochemical analysis of the leaf extract using dye yielding plant Bixa orellana. The synthesis of silver nanoparticles was detected by changing colour from yellowish green to brown after treatment with silver nitrate (1mM). ...

  19. 75 FR 38768 - Ashley National Forest, UT, High Uintas Wilderness-Colorado River Cutthroat Trout Habitat...

    Science.gov (United States)

    2010-07-06

    ... Forest Service Ashley National Forest, UT, High Uintas Wilderness--Colorado River Cutthroat Trout Habitat...) proposes to restore genetically pure Colorado River cutthroat trout (CRCT; Onchorhynchus clarki pleuriticus... District. Nonnative fish species to be removed are primarily brook trout (Salvelinus...

  20. Monodisperse Silver Nanoparticles Synthesized by a Microwave-Assisted Method

    Institute of Scientific and Technical Information of China (English)

    ZHU Shao-Peng; TANG Shao-Chun; MENG Xiang-Kang

    2009-01-01

    Silver nanoparticles with an average size of about 2Onto are synthesized in a colloidal solution with the aid of microwave irradiation. Neither additional reductant nor stabilizer is required in this microwave-assisted method.The color of the colloidal solution is found to be dark green, different from the characteristic yellow of silver colloidal solutions. The silver nanoparticles in the colloidal solution have a narrow size distribution and large yield quantity. UV-visible absorption spectroscopy analysis reveals that the as-synthesized monodisperse silver nanoparticles have exceptional optical properties. Raman spectroscopy measurements demonstrate that these silver nanoparticles exhibit a notable surface-enhanced Raman scattering ability.

  1. Silver and Cyanine Staining of Oligonucleotides in Polyacrylamide Gel

    OpenAIRE

    Tang, Weizhong; Zhou, Huafu; Li, Wei

    2015-01-01

    To explore why some oligonucleotides in denaturing polyacrylamide gel could not be silver-stained, 134 different oligonucleotides were analyzed using denaturing polyacrylamide gel electrophoresis stained with silver and asymmetric cyanine. As a result, we found that the sensitivity of oligos (dA), (dC), (dG) and (dT) to silver staining could be ranged as (dA) > (dG) > (dC) > (dT) from high to low. It was unexpected that oligo (dT) was hard to be silver-stained. Moreover, the silver staining o...

  2. Radiolytic reduction reaction of colloidal silver bromide solution

    International Nuclear Information System (INIS)

    The reduction reaction of colloidal silver bromide (AgBr3)2- in nitrous oxide gas saturated solution of some alcohols: methanol, ethanol, 2-propanol and 2-methyl-2-propanol by γ-irradiation was studied spectrophotometrically in order to elucidate the mechanism of the formation of colloidal silver bromide (AgBr3)3- at ambient temperature. The amount of colloidal silver bromide formed increases in the order: i-PrOH, EtOH, MeOH. In t-BuOH, colloidal silver bromide did not form. The relative reactivities of alcohols for colloidal silver bromide was also studied kinetically. (author)

  3. A century of poultry genetics

    OpenAIRE

    Tixier-Boichard, M.; Leenstra, F.R.; Flock, D.; Hocking, A D; Weigend, S

    2012-01-01

    The 20th Century saw an astonishing advance in our understanding of genetics and the scientific basis of the genetic improvement of farm animals. The application of genetic principles to chickens in the 1950s and 1960s led to a rapid change in the productivity and efficiency of laying hens and broiler chickens, turkeys and ducks. Subsequently, the application of increasingly powerful computers and sophisticated mathematical algorithms has increased the range of traits that could be successful...

  4. Determination of the silver content of ancient silver coins by neutron activation analysis

    International Nuclear Information System (INIS)

    A reactor neutron activation analysis procedure for the determination of the silver content of silver coins is described. The samples are irradiated for 1 s, cooled for 85 s and measured for 60 s with a Ge-detector. The analysis is based on the measurement of sup(110)Ag and sup(108)Ag. Aluminium is used for flux monitoring and pulse pile-up correction. A calibration curve is prepared by irradiating and measuring a series of discs with known silver contents. An average precision of +-2.1% is obtained. The analysis of coins with known silver contents shows good agreement with the given values. The analysis time is 2.5 minutes per sample. (author)

  5. PVDF nanofibers with silver nanoparticles and silver/titanium dioxide for antimicrobial applications

    International Nuclear Information System (INIS)

    PVDF nanofibers with and without nanoparticles were produced by the method of electro spinning using dimethylformamide (DMF). Silver nitrate nanoparticles (0,5 and 2 wt %) and silver/titanium dioxide nanoparticles obtained by the reduction method (2 wt %) were synthesized and added to the PVDF solution to prepared nanofibers. The processes of electrospinning and film preparation using PVDF with the nanoparticles were compared. Silver/titanium dioxide nanoparticles were characterized with X-ray diffraction (XRD), Scanning electron microscopy (SEM) with EDX and x-ray photoelectron spectroscopy (XPS) to show silver/titanium dioxide nanoparticles. Nanofibers mats were characterized with SEM to study the effects of the addition of the nanoparticles on the morphology behavior and spectroscopy by Fourier transform infrared (FTIR) to analyze the crystalline phase of PVDF films. (author)

  6. SRTM Anaglyph: Pinon Canyon region, Colorado

    Science.gov (United States)

    2001-01-01

    Erosional features are prominent in this view of southern Colorado taken by the Shuttle Radar Topography Mission (SRTM). The area covers about 20,000square kilometers and is located about 50 kilometers south of Pueblo, Colorado. The prominent mountains near the left edge of the image are the Spanish Peaks, remnants of a 20 million year old volcano. Rising 2,100 meters (7,000 feet) above the plains to the east, these igneous rock formations with intrusions of eroded sedimentary rock historically served as guiding landmarks for travelers on the Mountain Branch of the Santa Fe Trail.Near the center of the image is the Pinon Canyon Maneuver Site, a training area for soldiers of the U.S. Army from nearby Fort Carson. The site supports a diverse ecosystem with large numbers of big and small game, fisheries, non-game wildlife, forest, range land and mineral resources. It is bounded on the east by the dramatic topography of the Purgatoire River Canyon, a 100 meter (328 feet) deep scenic red canyon with flowing streams, sandstone formations and exposed geologic processes.This anaglyph was produced by first shading a preliminary SRTM elevation model. The stereoscopic effect was then created by generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter.Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR)that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed

  7. The 21st Century Skills Movement

    Science.gov (United States)

    Johnson, Paige

    2009-01-01

    Since 2002, the Partnership for 21st Century Skills has been the leading advocacy organization in the United States focused on infusing 21st century skills into education. Its "Framework for 21st Century Learning," the result of a consensus among hundreds of stakeholders, describes the skills, knowledge, and expertise students need to succeed in…

  8. Denitrification in marine shales in northeastern Colorado

    Science.gov (United States)

    McMahon, P.B.; Böhlke, J.K.; Bruce, B.W.

    1999-01-01

    Parts of the South Platte River alluvial aquifer in northeastern Colorado are underlain by the Pierre Shale, a marine deposit of Late Cretaceous age that is denitrification in the forms of organic carbon and sulfide minerals. Nested piezometers were sampled, pore water was squeezed from cores of shale, and an injection test was conducted to determine if denitrification in the shale was a sink for alluvial NO3/- and to measure denitrification rates in the shale. Measured values of NO3/-, N2, NH4/+, ??15[NO3/-], ??15N[N2], and ??15N[NH4/+] in the alluvial and shale pore water indicated that denitrification in the shale was a sink for alluvial NO3/-. Chemical gradients, reaction rate constants, and hydraulic head data indicated that denitrification in the shale was limited by the slow rate of NO3/- transport (possibly by diffusion) into the shale. The apparent in situ first-order rate constant for denitrification in the shale based on diffusion calculations was of the order of 0.04-0.4 yr-1, whereas the potential rate constant in the shale based on injection tests was of the order of 60 yr-1. Chemical data and mass balance calculations indicate that organic carbon was the primary electron donor for denitrification in the shale during the injection test, and ferrous iron was a minor electron donor in the process. Flux calculations for the conditions encountered at the site indicate that denitrification in the shale could remove only a small fraction of the annual agricultural NO3/- input to the alluvial aquifer. However, the relatively large potential first-order rate constant for denitrification in the shale indicated that the percentage of NO3/- uptake by the shale could be considerably larger in areas where NO3/- is transported more rapidly into the shale by advection.

  9. Uranium deposits: northern Denver Julesburg basin, Colorado

    International Nuclear Information System (INIS)

    The Fox Hills Sandstone and the Laramie Formation (Upper Cretaceous) are the host rocks for uranium deposits in Weld County, northern Denver Julesburg basin, Colorado. The uranium deposits discovered in the Grover and Sand Creek areas occur in well-defined north--south trending channel sandstones of the Laramie Formation whereas the sandstone channel in the upper part of the Fox Hills Sandstone trends east--west. Mineralization was localized where the lithology was favorable for uranium accumulation. Exploration was guided by log interpretation methods similar to those proposed by Bruce Rubin for the Powder River basin, Wyoming, because alteration could not be readily identified in drilling samples. The uranium host rocks consist of medium- to fine-grained carbonaceous, feldspathic fluvial channel sandstones. The uranium deposits consist of simple to stacked roll fronts. Reserve estimates for the deposits are: (1) Grover 1,007,000 lbs with an average grade of 0.14 percent eU3O8,2) Sand Creek 154,000 lbs with an average grade of 0.08 percent eU3O8, and 3) The Pawnee deposit 1,060,000 lbs with an average grade of 0.07 percent eU3O8. The configuration of the geochemical cells in the Grover and Sand Creek sandstones indicate that uraniferous fluids moved northward whereas in the Pawnee sandstone of the Fox Hills uraniferous fluids moved southward. Precipitation of uranium in the frontal zone probably was caused by downdip migration of oxygcnated groundwater high in uranium content moving through a favorable highly carbonaceous and pyritic host sandstone

  10. Interaction between silver and Zircaloy-4 at high temperatures

    International Nuclear Information System (INIS)

    Interaction between silver-indium-cadmium control rod alloy and Zircaloy-4 is an important reaction in the analysis of a severe accident of a PWR, since it has a great influence on the fuel bundle degradation. The authors have reported the results of the experiments on the interaction between silver-indium-cadmium alloy and Zircaloy-4. To examine the mechanism of this complex reaction system, reaction couples of silver, the main component of silver-indium-cadmium alloy, and Zircaloy-4 were isothermally heated in argon at the temperatures ranging from 1273 to 1473 K. The dissolution behavior of Zircaloy-4 in silver/Zircaloy-4 reaction was compared with that in silver-indium-cadmium alloy/Zircaloy-4 reaction and the role of indium was discussed. The reaction rate of silver/Zircaloy-4 reaction increased with the temperature increase and was low compared to that of silver-indium-cadmium alloy/Zircaloy-4 reaction. This difference is larger at lower test temperatures and is believed to be caused by the difference of melting points between silver-indium-cadmium alloy and silver. Two reactions show comparable reaction rate at 1473K. Silver/Zircaloy-4 reaction approximately obeyed the parabolic rate law, thereby reaction rate constants and an apparent activation energy, 580.8kJ/mol, were determined. (author)

  11. Reprotoxicity of gold, silver, and gold-silver alloy nanoparticles on mammalian gametes.

    Science.gov (United States)

    Tiedemann, Daniela; Taylor, Ulrike; Rehbock, Christoph; Jakobi, Jurij; Klein, Sabine; Kues, Wilfried A; Barcikowski, Stephan; Rath, Detlef

    2014-03-01

    Metal and alloy nanoparticles are increasingly developed for biomedical applications, while a firm understanding of their biocompatibility is still missing. Various properties have been reported to influence the toxic potential of nanoparticles. This study aimed to assess the impact of nanoparticle size, surface ligands and chemical composition of gold, silver or gold-silver alloy nanoparticles on mammalian gametes. An in vitro assay for porcine gametes was developed, since these are delicate primary cells, for which well-established culture systems exist and functional parameters are defined. During coincubation with oocytes for 46 h neither any of the tested gold nanoparticles nor the gold-silver alloy particles with a silver molar fraction of up to 50% showed any impact on oocyte maturation. Alloy nanoparticles with 80% silver molar fraction and pure silver nanoparticles inhibited cumulus-oocyte maturation. Confocal microscopy revealed a selective uptake of gold nanoparticles by oocytes, while silver and alloy particles mainly accumulated in the cumulus cell layer surrounding the oocyte. Interestingly sperm vitality parameters (motility, membrane integrity and morphology) were not affected by any of the tested nanoparticles. Only sporadic association of nanoparticles with the sperm plasma membrane was found by transmission electron microscopy. In conclusion, mammalian oocytes were sensitive to silver containing nanoparticles. Likely, the delicate process of completing meiosis in maternal gametes features high vulnerability towards nanomaterial derived toxicity. The results imply that released Ag(+)-ions are responsible for the observed toxicity, but the compounding into an alloy seemed to alleviate the toxic effects to a certain extent. PMID:24171189

  12. Highly efficient silver patterning without photo-resist using simple silver precursors

    International Nuclear Information System (INIS)

    Highly efficient method for silver patterning without photo-resist was developed by using high photosensitive organo-silver precursors, which were prepared by a simple reaction of silver salts and excess of amines. The FT-IR and GC-MS spectra were recorded depending on UV exposure time, for (n-PrNH2)Ag(NO3).0.5MeCN and (n-PrNH2)Ag(NO2).0.5MeCN, to understand the photolysis mechanism. The results indicate not only dissociation of coordinated amine and acetonitrile, but also decomposition of corresponding anion upon UV irradiation. When a precursor thin film was exposed to broadband UV irradiation, a partially reduced and insoluble silver species were formed within several minutes. After development, the irradiated areas were treated with a reducing agent to obtain pure metallic patterns. Subsequently, annealing step was followed at 100-350 deg. C to increase the adhesion of interface and cohesion of silver particles. The line resolution of 5 μm was obtained by the present silver precursors. Film thickness was also controllable from 50 to 250 nm by repetition of the above procedure. The average electrical conductivity was in the range of 3-43 Ω cm, measured by four-point probe technique. AES depth profile of the silver pattern thus obtained showed carbon and oxygen contents are less than 1% through the whole range. Even though sulfur contaminant exists on the surface, it was believed that nearly pure silver pattern was generated

  13. Metal-Enhanced Fluorescence of Silver Island Associated with Silver Nanoparticle

    OpenAIRE

    Liaw, Jiunn-Woei; Wu, Hsin-Yu; Huang, Chu-Chuan; Kuo, Mao-Kuen

    2016-01-01

    The coupling plasmon of a hybrid nanostructure, silver island (SI) associated with silver nanoparticle (SNP), on metal-enhanced fluorescence (MEF) was studied theoretically. We used the multiple multipole method to analyze the plasmon-mediated enhancement factor on the fluorescence of a molecule immobilized on SNP and located in the gap zone between SI and SNP; herein, the SI was modeled as an oblate spheroid. Numerical results show that the enhancement factor of the hybrid nanostructure is h...

  14. The molecular orientation of PNBA on silver nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The molecular orientations of p-nitrobenzoic acid (PNBA) on the surface of silver nanoparticles and silver mirror have been investigated by using surface enhanced Raman scattering (SERS) and UV-visible absorption spectroscopy. In the mixed system of silver colloid/PNBA/ethanol, the orientation of PNBA on silver nanoparticles remarkably different from that on silver mirror was observed, and it mainly resulted from the cooperation effect of the adsorption to surface active sites on silver under the pressure of aqueous molecules. This result is of some significance for further studying surface-interfacial structures and properties of silver nanoparticles, and the technique used in this note is feasible to get the SERS spectra of some molecules insoluble in aqueous solution.

  15. Study of the Electroless Silver Seed Formation on Silicon Surface

    Institute of Scientific and Technical Information of China (English)

    TONG Hao; WANG Chun-Ming; YE Wei-Chun; CHANG Yan-Long; LI Hu-Lin

    2007-01-01

    The silver seed on silicon was prepared through aqueous HF and AgNO3 solution at room temperature. In order to explore the formation process of silver seed on silicon, the methods of open circuit potential with time (OCP-t),anodic stripping sweep voltammetry (ASV) and scanning tunneling microscope (STM) were used in this work. The procedure of silver nucleus growing into large particles was explained by electro-negativity. The growth mechanism of silver seed on silicon has been presented: at first, the silver monolayer and multilayer firstly grows onto silicon without fully covering the surface at the expense of silicon etching due to the silver seed attracting the electron from silicon, after that, the monolayer coalesces together, forming continuous grain film with some silver atoms diffusing into the silicon and the multilayer still grows thick simultaneously.

  16. Evaluation of the antimicrobial efficacy of phytogenic silver nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Prasad TNVKV; Elumalai EK; Khateeja S

    2011-01-01

    Objective: To evaluate the antimicrobial activity of silver nanoparticles synthesized fromPsidium guajava (P. guajava) against human pathogens. Methods: Ultraviolet-visible (UV-Vis) spectrophotometry and transmission electron microscopy (TEM) were performed to confirm the formation and stability of silver nanparticles. Antimicrobial activities of the synthesized Ag nanoparticles were determined using the agar well diffusion assay method. Results: UV-Vis spectrum of the aqueous medium containing silver nanoparticles showed absorption peak at around 410 nm. TEM showed the formation of silver nanoparticles with an average size of 59 nm. The formed silver nanoparticles showed good antimicrobial activity against Escherichia coli,Bacillus cereus and Candida tropicalis. Conclusions: P. guajava demonstrated strong potential for synthesis of silver nanoparticles by rapid reduction of silver ions (Ag+ to Ag0). Biological methods are a good competent for the chemical procedures, which are environment friendly and convenient.

  17. Synthesis and characterization of silver nanoparticles by sonoelectrodeposition

    Institute of Scientific and Technical Information of China (English)

    CHENG Jingquan; YAO Suwei

    2005-01-01

    Shaped silver nanoparticles with sphere, wire and dendrite were prepared by sonoelectrochemical deposition from an aqueous solution of AgNO3 in the presence of ethylenediaminetetraacetic acid disodium salt (EDTA) and polyvinylpyrrolidone (PVP). The diameter of spherical silver particles was about 30 nm. The diameter of the silver nanowires was also about 30 nm and the length was 200-900 nm. The dendrites were synthesized with the concentration of silver solution increasing. Silver nanoparticles were characterized by transmission electron microscope (TEM), X-ray powder diffraction (XRD), scanning probe microscope (SPM) and UV-vis absorption spectrum. XRD patterns revealed that silver particles were of face-centered cubic structure. UV-vis absorption spectra indicated that different morphology and size of silver particles could influence the optical properties.

  18. Phytochemical Synthesis and Preliminary Characterization of Silver Nanoparticles Using Hesperidin

    International Nuclear Information System (INIS)

    his paper is the first of its kind for development of rapid and ecofriendly method for synthesis of silver nanoparticles from aqueous solution of silver nitrate using the flavonoid “hesperidin” and optimization of the methodology. There is formation of stable spherical silver nanoparticles in the size range of 20–40nm. Optimization of methodology in terms of concentration of reactants and pH of the reaction mixture reduced the reaction time for silver nanoparticle formation to 2mins. Silver nanoparticles (AgNPs) were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). UV-vis spectroscopy derived spectrum demonstrated a peak of 430nm which corresponds to the plasmon absorbance of silver nanoparticles. Transmission electron microscopy revealed spherical shaped silver nanoparticles in the size range of 20–40nm.

  19. Extracellular biosynthesis of silver nanoparticles using the fungus Fusarium semitectum

    International Nuclear Information System (INIS)

    Development of environmental friendly procedures for the synthesis of metal nanoparticles through biological processes is evolving into an important branch of nanobiotechnology. In this paper, we report on the use of fungus 'Fusarium semitectum' for the extracellular synthesis of silver nanoparticles from silver nitrate solution (i.e. through the reduction of Ag+ to Ag0). Highly stable and crystalline silver nanoparticles are produced in solution by treating the filtrate of the fungus F. semitectum with the aqueous silver nitrate solution. The formations of nanoparticles are understood from the UV-vis and X-ray diffraction studies. Transmission electron microscopy of the silver particles indicated that they ranged in size from 10 to 60 nm and are mostly spherical in shape. Interestingly the colloidal suspensions of silver nanoparticles are stable for many weeks. Possible medicinal applications of these silver nanoparticles are envisaged

  20. Role of Silver-Nano Particles in Drug Discovery Research

    Directory of Open Access Journals (Sweden)

    Richa Khare

    2016-03-01

    Full Text Available is the only precious metal has been used to fight infection for thousands of years. Hippocrates first described its antimicrobial properties in 400 BC but how it works has been a mystery. It has a long history as an antibiotic in human health care and also used for many purposes. Silver compounds are very effective antibacterial agents against both aerobic and anaerobic bacteria. It has been developed for use in water purification, wound care, bone prostheses, reconstructive orthopaedic surgery, cardiac devices, catheters and surgical appliances. Advancing biotechnology has enabled incorporation of ionizable silver into fabrics for clinical use to reduce the risk of infections and for personal hygiene. The antimicrobial action of silver or silver compounds is proportional to the bioactive silver ion (Ag (+ released and its availability to interact with bacterial or fungal cell membranes. Silver metal and inorganic silver compounds ionize in the presence of water, body fluids or tissue exudates

  1. Synthesis of silver nanoparticles in melts of amphiphilic polyesters

    International Nuclear Information System (INIS)

    The current work presents a one-step procedure for the synthesis of amphiphilic silver nanoparticles suitable for production of silver-filled polymeric materials. This solvent free synthesis via reduction of Tollens’ reagent as silver precursor in melts of amphiphilic polyesters consisting of hydrophilic poly(ethylene glycol) blocks and hydrophobic alkyl chains allows the production of silver nanoparticles without any by-product formation. This makes them especially interesting for the production of medical devices with antimicrobial properties. In this article the influences of the chain length of the hydrophobic block in the amphiphilic polyesters and the process temperature on the particle size distribution (PSD) and the stability of the particles against agglomeration are discussed. According to the results of spectroscopic and viscosimetric investigations the silver precursor is reduced to elemental silver nanoparticles by a single electron transfer process from the poly(ethylene glycol) chain to the silver ion. (paper)

  2. Environmental assessment, expanded Ponnequin wind energy project, Weld County, Colorado

    International Nuclear Information System (INIS)

    The US Department of Energy (DOE) has considered a proposal from the State of Colorado, Office of Energy Conservation (OEC), for funding construction of the Expanded Ponnequin Wind Project in Weld County, Colorado. OEC plans to enter into a contracting arrangement with Public Service Company of Colorado (PSCo) for the completion of these activities. PSCo, along with its subcontractors and business partners, are jointly developing the Expanded Ponnequin Wind Project. The purpose of this Final Environmental Assessment (EA) is to provide DOE and the public with information on potential environmental impacts associated with the Expanded Ponnequin Wind Energy Project. This EA, and public comments received on it, were used in DOE's deliberations on whether to release funding for the expanded project under the Commercialization Ventures Program

  3. Environmental assessment, expanded Ponnequin wind energy project, Weld County, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-02-01

    The US Department of Energy (DOE) has considered a proposal from the State of Colorado, Office of Energy Conservation (OEC), for funding construction of the Expanded Ponnequin Wind Project in Weld County, Colorado. OEC plans to enter into a contracting arrangement with Public Service Company of Colorado (PSCo) for the completion of these activities. PSCo, along with its subcontractors and business partners, are jointly developing the Expanded Ponnequin Wind Project. The purpose of this Final Environmental Assessment (EA) is to provide DOE and the public with information on potential environmental impacts associated with the Expanded Ponnequin Wind Energy Project. This EA, and public comments received on it, were used in DOE`s deliberations on whether to release funding for the expanded project under the Commercialization Ventures Program.

  4. Making climate change projections relevant to water management: opportunities and challenges in the Colorado River basin (Invited)

    Science.gov (United States)

    Vano, J. A.

    2013-12-01

    By 2007, motivated by the ongoing drought and release of new climate model projections associated with the IPCC AR4 report, multiple independent studies had made estimates of future Colorado River streamflow. Each study had a unique approach, and unique estimate for the magnitude for mid-21st century streamflow change ranging from declines of only 6% to declines of as much as 45%. The differences among studies provided for interesting scientific debates, but to many practitioners this appeared to be just a tangle of conflicting predictions, leading to the question 'why is there such a wide range of projections of impacts of future climate change on Colorado River streamflow, and how should this uncertainty be interpreted?' In response, a group of scientists from academic and federal agencies, brought together through a NOAA cross-RISA project, set forth to identify the major sources of disparities and provide actionable science and guidance for water managers and decision makers. Through this project, four major sources of disparities among modeling studies were identified that arise from both methodological and model differences. These differences, in order of importance, are: (1) the Global Climate Models (GCMs) and emission scenarios used; (2) the ability of land surface hydrology and atmospheric models to simulate properly the high elevation runoff source areas; (3) the sensitivities of land surface hydrology models to precipitation and temperature changes; and (4) the methods used to statistically downscale GCM scenarios. Additionally, reconstructions of pre-instrumental streamflows provided further insights about the greatest risk to Colorado River streamflow of a multi-decadal drought, like those observed in paleo reconstructions, exacerbated by a steady reduction in flows due to climate change. Within this talk I will provide an overview of these findings and insights into the opportunities and challenges encountered in the process of striving to make

  5. Electrospun polyacrylonitrile nanofibers loaded with silver nanoparticles by silver mirror reaction.

    Science.gov (United States)

    Shi, Yongzheng; Li, Yajing; Zhang, Jianfeng; Yu, Zhongzhen; Yang, Dongzhi

    2015-06-01

    The silver mirror reaction (SMR) method was selected in this paper to modify electrospun polyacrylonitrile (PAN) nanofibers, and these nanofibers loaded with silver nanoparticles showed excellent antibacterial properties. PAN nanofibers were first pretreated in AgNO3 aqueous solution before the SMR process so that the silver nanoparticles were distributed evenly on the outer surface of the nanofibers. The final PAN nanofibers were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), TEM-selected area electron diffraction (SAED), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). SEM, TEM micrographs and SAED patterns confirmed homogeneous dispersion of the silver nanoparticles which were composed of monocrystals with diameters 20-30nm. EDS and XRD results showed that these monocrystals tended to form face-centered cubic single silver. TGA test indicated that the nanoparticles loaded on the nanofibers reached above 50wt.%. This material was also evaluated by the viable cell-counting method. The results indicated that PAN nanofibers loaded with silver nanoparticles exhibited excellent antimicrobial activities against gram-negative Escherichia coli (E. coli), gram-positive Staphylococcus aureus (S. aureus) and the fungus Monilia albicans. Thus, this material had many potential applications in biomedical fields. PMID:25842144

  6. Nanostructuration of starch/silver and starch/silver/montmorillonites nanocomposites films with green process : influence of the silver nanoparticles generation routes on structure and transport properties

    OpenAIRE

    Cheviron, Perrine

    2015-01-01

    The present work reports a strategy involving the preparation of silver nanoparticles in a biodegradable polymer stemming from either an ex situ or an in situ method, using in both cases a completely green chemistry process. The influence of the reducing agent concentration and the silver nanoparticles generation route is investigated on the structure, the morphology and the properties of the nanocomposite films. In both routes, silver nanoparticles with a diameter below 30 nm were highlighte...

  7. 78 FR 69985 - Irish Potatoes Grown in Colorado; Decreased Assessment Rate for Area No. 2

    Science.gov (United States)

    2013-11-22

    ... approved, an assessment rate for Colorado Area No. 2 that would continue in effect from fiscal period to..., 2013, an assessment rate of $0.0033 per hundredweight is established for Colorado Area No. 2 potatoes... Agricultural Marketing Service 7 CFR Part 948 Irish Potatoes Grown in Colorado; Decreased Assessment Rate...

  8. 40 CFR 52.331 - Committal SIP for the Colorado Group II PM10 areas.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Committal SIP for the Colorado Group II... SIP for the Colorado Group II PM10 areas. On April 14, 1989, the Governor submitted a Committal SIP for the Colorado Group II PM10 areas. The SIP commits the State to continue to monitor for...

  9. 76 FR 77549 - Colorado River Indian Tribes-Amendment to Health & Safety Code, Article 2. Liquor

    Science.gov (United States)

    2011-12-13

    ... Bureau of Indian Affairs Colorado River Indian Tribes--Amendment to Health & Safety Code, Article 2... amendment to the Colorado River Tribal Health and Safety Code, Article 2. Liquor, Section 2-403(12). The... Indian Tribal Council adopted this amendment to the Colorado River Tribal Health and Safety Code,...

  10. 78 FR 72706 - Notice of Inventory Completion: Colorado State University, Fort Collins, CO

    Science.gov (United States)

    2013-12-03

    ... National Park Service Notice of Inventory Completion: Colorado State University, Fort Collins, CO AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: Colorado State University (CSU) has completed an... in this notice by January 2, 2014. ADDRESSES: Christopher Green, Colorado State University,...

  11. 75 FR 45657 - Notice of Inventory Completion: University of Colorado Museum, Boulder, CO

    Science.gov (United States)

    2010-08-03

    ... National Park Service Notice of Inventory Completion: University of Colorado Museum, Boulder, CO AGENCY... of human remains in the control of the University of Colorado Museum, Boulder, CO. The human remains... this notice. A detailed assessment of the human remains was made by the University of Colorado...

  12. 75 FR 28647 - Notice of Inventory Completion: University of Colorado Museum, Boulder, CO

    Science.gov (United States)

    2010-05-21

    ... National Park Service Notice of Inventory Completion: University of Colorado Museum, Boulder, CO AGENCY... of human remains in the possession of the University of Colorado Museum, Boulder, CO. The human... this notice. A detailed assessment of the human remains was made by University of Colorado...

  13. 76 FR 62839 - Notice of Inventory Completion: University of Colorado Museum, Boulder, CO

    Science.gov (United States)

    2011-10-11

    ... National Park Service Notice of Inventory Completion: University of Colorado Museum, Boulder, CO AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: The University of Colorado Museum has completed... contact the University of Colorado Museum. Disposition of the human remains to the Indian tribes...

  14. 75 FR 26988 - Notice of Inventory Completion: University of Colorado Museum, Boulder, CO

    Science.gov (United States)

    2010-05-13

    ... National Park Service Notice of Inventory Completion: University of Colorado Museum, Boulder, CO AGENCY... of human remains in the possession of the University of Colorado Museum, Boulder, CO. The human... this notice. A detailed assessment of the human remains was made by University of Colorado...

  15. 75 FR 42771 - Notice of Inventory Completion: University of Colorado Museum, Boulder, CO

    Science.gov (United States)

    2010-07-22

    ... National Park Service Notice of Inventory Completion: University of Colorado Museum, Boulder, CO AGENCY... of human remains and associated funerary objects in the control of the University of Colorado Museum... assessment of the human remains was made by the University of Colorado Museum professional staff...

  16. 75 FR 77898 - Notice of Inventory Completion: University of Colorado Museum, Boulder, CO

    Science.gov (United States)

    2010-12-14

    ... National Park Service Notice of Inventory Completion: University of Colorado Museum, Boulder, CO AGENCY... of human remains in the possession of the ] University of Colorado Museum, Boulder, CO. The human... made by University of Colorado Museum professional staff in consultation with representatives of...

  17. 78 FR 59960 - Notice of Inventory Completion: Colorado State University, Fort Collins, CO

    Science.gov (United States)

    2013-09-30

    ... National Park Service Notice of Inventory Completion: Colorado State University, Fort Collins, CO AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: Colorado State University has completed an... remains should submit a written request to Colorado State University, Department of Anthropology. If...

  18. 78 FR 50103 - Notice of Inventory Completion: Colorado State University, Fort Collins, CO

    Science.gov (United States)

    2013-08-16

    ... National Park Service Notice of Inventory Completion: Colorado State University, Fort Collins, CO AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: Colorado State University has completed an... remains should submit a written request to Colorado State University, Department of Anthropology. If...

  19. 75 FR 45655 - Notice of Inventory Completion: University of Colorado Museum, Boulder, CO

    Science.gov (United States)

    2010-08-03

    ... National Park Service Notice of Inventory Completion: University of Colorado Museum, Boulder, CO AGENCY... of human remains in the control of the University of Colorado Museum, Boulder, CO. The human remains.... A detailed assessment of the human remains was made by the University of Colorado...

  20. 75 FR 57290 - Notice of Inventory Completion: University of Colorado Museum, Boulder, CO

    Science.gov (United States)

    2010-09-20

    ... National Park Service Notice of Inventory Completion: University of Colorado Museum, Boulder, CO AGENCY... of human remains and associated funerary objects in the control of the University of Colorado Museum... assessment of the human remains was made by the University of Colorado Museum professional staff...

  1. 76 FR 62833 - Notice of Inventory Completion: University of Colorado Museum, Boulder, CO

    Science.gov (United States)

    2011-10-11

    ... National Park Service Notice of Inventory Completion: University of Colorado Museum, Boulder, CO AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: The University of Colorado Museum has completed... contact the University of Colorado Museum. Disposition of the human remains and associated funerary...

  2. 2010 Kids Count in Colorado! Far from Average: Growing Gaps in Child Well-Being

    Science.gov (United States)

    Colorado Children's Campaign, 2010

    2010-01-01

    "Kids Count in Colorado!" is an annual publication of the Colorado Children's Campaign, which provides the best available state- and county-level data to measure and track the education, health and general well-being of the state's children. "Kids Count in Colorado!" informs policy debates and community discussions, serving as a valuable resource…

  3. Biosynthesis and structural characterization of silver nanoparticles from bacterial isolates

    International Nuclear Information System (INIS)

    Graphical abstract: In this study five bacterial isolates belong to different genera were found to be able to biosynthesize silver nanoparticles. Biosynthesis and spectral characterization are reported here. Highlights: → About 300 bacterial isolates were screened for their ability to produce nanosilvers → Five of them were potential candidates for synthesis of silver nanoparticles → Production of silver nanoparticles was examined using UV-Vis, XRD, SEM and EDS. → The presence of nanoparticles with all five bacterial isolates was confirmed. -- Abstract: This study aimed to develop a green process for biosynthesis of silver nanomaterials by some Egyptian bacterial isolates. This target was achieved by screening an in-house culture collection consists of 300 bacterial isolates for silver nanoparticle formation. Through screening process, it was observed that strains belonging to Escherichia coli (S30, S78), Bacillus megaterium (S52), Acinetobacter sp. (S7) and Stenotrophomonas maltophilia (S54) were potential candidates for synthesis of silver nanoparticles. The extracellular production of silver nanoparticles by positive isolates was investigated by UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results demonstrated that UV-visible spectrum of the aqueous medium containing silver ion showed a peak at 420 nm corresponding to the plasmon absorbance of silver nanoparticles. Scanning electron microscopy micrograph showed formation of silver nanoparticles in the range of 15-50 nm. XRD-spectrum of the silver nanoparticles exhibited 2θ values corresponding to the silver nanocrystal that produce in hexagonal and cubic crystal configurations with different plane of orientation. In addition, the signals of the silver atoms were observed by EDS-spectrum analysis that confirms the presence of silver nanoparticles (AgNPs) in all positive

  4. Biosynthesis and structural characterization of silver nanoparticles from bacterial isolates

    Energy Technology Data Exchange (ETDEWEB)

    Zaki, Sahar, E-mail: saharzaki@yahoo.com [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt); El Kady, M.F. [Fabrication Technology Department, Advanced Technology and New Materials Research Institute (ATNMRI), Mubarak City for Scientific Research and Technology Applications, Alexandria (Egypt); Abd-El-Haleem, Desouky [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt)

    2011-10-15

    Graphical abstract: In this study five bacterial isolates belong to different genera were found to be able to biosynthesize silver nanoparticles. Biosynthesis and spectral characterization are reported here. Highlights: {yields} About 300 bacterial isolates were screened for their ability to produce nanosilvers {yields} Five of them were potential candidates for synthesis of silver nanoparticles {yields} Production of silver nanoparticles was examined using UV-Vis, XRD, SEM and EDS. {yields} The presence of nanoparticles with all five bacterial isolates was confirmed. -- Abstract: This study aimed to develop a green process for biosynthesis of silver nanomaterials by some Egyptian bacterial isolates. This target was achieved by screening an in-house culture collection consists of 300 bacterial isolates for silver nanoparticle formation. Through screening process, it was observed that strains belonging to Escherichia coli (S30, S78), Bacillus megaterium (S52), Acinetobacter sp. (S7) and Stenotrophomonas maltophilia (S54) were potential candidates for synthesis of silver nanoparticles. The extracellular production of silver nanoparticles by positive isolates was investigated by UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results demonstrated that UV-visible spectrum of the aqueous medium containing silver ion showed a peak at 420 nm corresponding to the plasmon absorbance of silver nanoparticles. Scanning electron microscopy micrograph showed formation of silver nanoparticles in the range of 15-50 nm. XRD-spectrum of the silver nanoparticles exhibited 2{theta} values corresponding to the silver nanocrystal that produce in hexagonal and cubic crystal configurations with different plane of orientation. In addition, the signals of the silver atoms were observed by EDS-spectrum analysis that confirms the presence of silver nanoparticles (Ag

  5. Low temperature processable binderless silver inks for flexible electronics

    Science.gov (United States)

    Nayak, Arun

    2013-01-01

    A new class of screen-printable conductive silver inks that can be transformed into conductive traces at temperatures below 120°C is presented. The low transformation temperature required for processing these inks renders them suitable for printing on flexible substrates, such as polyester films to form conductive patterns/devices. The ink composition includes silver flakes (average particle size of 0.45 μm-8 μm), an organometallic silver salt, a free radical initiator and a novel dispersant. This binder-free silver ink can be thermally converted into pure metallic patterns containing no binder or any other organic moieties. The initiator catalyzes the decomposition of organometallic silver compounds to produce reactive silver at a relatively lower temperature. The silver thus generated chemically welds the silver flakes. Conductive silver traces with conductivities approaching within two orders of magnitude of elemental silver have been fabricated using these inks. In addition, a novel dispersant comprising amine-carbamate based gels was also developed. These gels act as suitable transport agents for the ink and completely decompose and vaporize during the thermal transformation process. The ink was formulated after careful optimization of the particle sizes of the silver flakes, weight percentages of the silver organometallic salt, silver flakes and amine carbamate gel and the relative molar ratio of the silver salt to the catalyst. These factors influence the conductivity and the mechanical integrity of the printed patterns fabricated from the ink. The inks have also been characterized for their rheological properties to assess their suitability for being processed using commercial roll to roll manufacturing processes such as screen, flexographic or gravure printing. The inks show shear thinning behavior with a viscosity in the range of 5-6.6 Pa.s at 1000 s-1, which within commercially acceptable ranges. Applications of these inks range from interconnect for

  6. Process for making silver metal filaments

    Energy Technology Data Exchange (ETDEWEB)

    Bamberger, C.E.

    1998-04-01

    This invention relates to a process for making filaments of metal compounds and more particularly to a process for making silver metal filaments. The United States Government has rights to this invention pursuant to Contract No. DE-AC05-8421400 with Lockheed Martin Energy Systems, Inc. awarded by the US Department of Energy.

  7. Radon capture with silver exchanged zeolites

    International Nuclear Information System (INIS)

    To enable laboratory work with larger amounts of 226Ra and its decay products, e.g., 222Rn and its daughters, these need to be captured in order to avoid unnecessary alpha contamination of the laboratory work space and ventilation systems. In this study, radon gas was pumped through a column filled with the silver exchanged zeolite called 'silver exchanged molecular sieves 13X' (Ag84Na2[(AlO2)86(SiO2)106].xH2O). After exposure to radon, the radioactivity of the zeolite was measured repeatedly using high resolution gamma spectrometry. It was shown that radon was captured and retained in the silver exchanged zeolite. The zeolites' ability to retain radon was decreased by formation of metallic silver, caused by ionizing radiation. However, the zeolite was regenerated by heating and its radon capture ability was restored. The daughters of radon are not in gas phase and will hence stay on the column. (orig.)

  8. Regenerating evanescent waves from a silver superlens.

    Science.gov (United States)

    Fang, Nicholas; Liu, Zhaowei; Yen, Ta-Jen; Zhang, Xiang

    2003-04-01

    We investigated a precursor of superlensing: regenerating evanescent waves by excitation of a surface plasmon. Because the permittivity of a silver slab approaches -1, we experimentally observed a broadening of surface-plasmon bandwidth. Our study identifies a means to access deep subwavelength features by use of a metamaterial superlens. PMID:19461779

  9. Regenerating evanescent waves from a silver superlens

    Science.gov (United States)

    Fang, Nicholas; Liu, Zhaowei; Yen, Ta-Jen; Zhang, Xiang

    2003-04-01

    We investigated a precursor of superlensing: regenerating evanescent waves by excitation of a surface plasmon. Because the permittivity of a silver slab approaches -1, we experimentally observed a broadening of surface-plasmon bandwidth. Our study identifies a means to access deep subwavelength features by use of a metamaterial superlens.

  10. Colloidal silver solutions with antimicrobial properties

    Energy Technology Data Exchange (ETDEWEB)

    Petica, A. [INCDIE ICPE-Advanced Research, Bucharest (Romania)], E-mail: petica@icpe-ca.ro; Gavriliu, S.; Lungu, M.; Buruntea, N. [INCDIE ICPE-Advanced Research, Bucharest (Romania); Panzaru, C. [Institute of Medicine and Pharmacy, Iassy (Romania)

    2008-08-25

    Some colloidal silver solutions involving the electrochemical technique with 'sacrificial anode method and different stabilizers and co-stabilizers' have been prepared. A constant current pulse generator with stirrer at different working times has been used. To achieve stable colloidal silver solutions, a mix of different tensioactive agents namely [poly (N-vinylpyrrolidone)], Na-naphthalene sulphonate, Na-lauryl sulfate and Na-dodecyl sulphonate were tested. The effects of these various mixes of polymer and ionic surfactants upon the Ag concentration and UV-vis spectra of silver nanoparticles were determined by spectrophotometer techniques. The nanoparticles sizes have been analyzed through dynamic light scattering technique and the silver nanoparticle morphology has been evidenced by transmission electron microscopy (TEM). Micobiological analysis has been made by determining minimal inhibitorial concentration upon the following germs: Staphylococcus aureus (ATCC) (Gram-positive cocci), Pseudomonas aeruginosa (ATTC), Escherichia coli (ATCC) and Acinetobacter spp. (Gram-negative coccobacillus). To evaluate the antifungal effect, the antibiogram method involving various tests using a fungi mix of Aspergillus, Penicillium and Trichoderma species has been used. The presented method allows obtaining of some stable colloidal solutions containing up to 35 ppm of Ag with very good antimicrobial and antifungal properties.

  11. Colloidal silver solutions with antimicrobial properties

    International Nuclear Information System (INIS)

    Some colloidal silver solutions involving the electrochemical technique with 'sacrificial anode method and different stabilizers and co-stabilizers' have been prepared. A constant current pulse generator with stirrer at different working times has been used. To achieve stable colloidal silver solutions, a mix of different tensioactive agents namely [poly (N-vinylpyrrolidone)], Na-naphthalene sulphonate, Na-lauryl sulfate and Na-dodecyl sulphonate were tested. The effects of these various mixes of polymer and ionic surfactants upon the Ag concentration and UV-vis spectra of silver nanoparticles were determined by spectrophotometer techniques. The nanoparticles sizes have been analyzed through dynamic light scattering technique and the silver nanoparticle morphology has been evidenced by transmission electron microscopy (TEM). Micobiological analysis has been made by determining minimal inhibitorial concentration upon the following germs: Staphylococcus aureus (ATCC) (Gram-positive cocci), Pseudomonas aeruginosa (ATTC), Escherichia coli (ATCC) and Acinetobacter spp. (Gram-negative coccobacillus). To evaluate the antifungal effect, the antibiogram method involving various tests using a fungi mix of Aspergillus, Penicillium and Trichoderma species has been used. The presented method allows obtaining of some stable colloidal solutions containing up to 35 ppm of Ag with very good antimicrobial and antifungal properties

  12. Characterization of silver nanoparticles deposited on montmorillonite

    Czech Academy of Sciences Publication Activity Database

    Praus, P.; Turicová, M.; Machovič, V.; Študentová, S.; Klementová, Mariana

    2010-01-01

    Roč. 49, č. 3 (2010), s. 341-345. ISSN 0169-1317 Institutional research plan: CEZ:AV0Z40320502 Keywords : silver nanoparticles * formaldehyde and borohydride reduction * montmorillonite * surface enhanced Raman scattering Subject RIV: CA - Inorganic Chemistry Impact factor: 2.303, year: 2010

  13. Interaction of Silver Nanopowder with Cooper Substrate

    Czech Academy of Sciences Publication Activity Database

    Sopoušek, J.; Buršík, Jiří; Zálešák, J.; Buršíková, V.; Brož, P.

    2011-01-01

    Roč. 43, - (2011), s. 33-38. ISSN 0350-820X R&D Projects: GA ČR(CZ) GA106/09/0700 Institutional research plan: CEZ:AV0Z20410507 Keywords : silver * copper * sintering Subject RIV: JG - Metallurgy Impact factor: 0.274, year: 2011

  14. Gelatin-stabilized polyaniline-silver colloids

    Czech Academy of Sciences Publication Activity Database

    Bober, Patrycja; Humpolíček, P.; Stejskal, Jaroslav

    Bordeaux: European Colloid and Interface Society, 2015. P11-26. [Conference of the European Colloid and Interface Society /29./ - ECIS 2015. 06.09.2015-11.09.2015, Bordeaux] R&D Projects: GA ČR(CZ) GP14-05568P Institutional support: RVO:61389013 Keywords : polyaniline * colloid * silver nanoparticles Subject RIV: JI - Composite Materials

  15. Reinforcement of Conducting Silver-based Materials

    Directory of Open Access Journals (Sweden)

    Heike JUNG

    2014-09-01

    Full Text Available Silver is a well-known material in the field of contact materials because of its high electrical and thermal conductivity. However, due to its bad mechanical and switching properties, silver alloys or reinforcements of the ductile silver matrix are required. Different reinforcements, e. g. tungsten, tungsten carbide, nickel, cadmium oxide or tin oxide, are used in different sectors of switches. To reach an optimal distribution of these reinforcements, various manufacturing techniques (e. g. powder blending, preform infiltration, wet-chemical methods, internal oxidation are being used for the production of these contact materials. Each of these manufacturing routes offers different advantages and disadvantages. The mechanical alloying process displays a successful and efficient method to produce particle-reinforced metal-matrix composite powders. This contribution presents the obtained fine disperse microstructure of tungsten-particle-reinforced silver composite powders produced by the mechanical alloying process and displays this technique as possible route to provide feedstock powders for subsequent consolidation processes. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4889

  16. Biosynthesis of Silver Nanoparticles Using Chenopodium ambrosioides

    Directory of Open Access Journals (Sweden)

    Luis M. Carrillo-López

    2014-01-01

    Full Text Available Biosynthesis of silver nanoparticles (AgNPs was achieved using extract of Chenopodium ambrosioides as a reducer and coating agent at room temperature (25°C. Two molar solutions of AgNO3 (1 mM and 10 mM and five extract volumes (0.5, 1, 2, 3, and 5 mL were used to assess quantity, shape, and size of the particles. The UV-Vis spectra gave surface plasmon resonance at 434–436 nm of the NPs synthesized with AgNO3 10 mM and all extract volumes tested, showing a direct relationship between extract volumes and quantity of particles formed. In contrast, the concentration of silver ions was related negatively to particle size. The smallest (4.9 ± 3.4 nm particles were obtained with 1 mL of extract in AgNO3 10 mM and the larger amount of particles were obtained with 2 mL and 5 mL of extract. TEM study indicated that the particles were polycrystalline and randomly oriented with a silver structure face centered cubic (fcc and fourier transform infrared spectroscopy (FTIR indicated that disappearance of the –OH group band after bioreduction evidences its role in reducing silver ions.

  17. Antibacterial properties of polyaniline-silver films

    Czech Academy of Sciences Publication Activity Database

    Kuceková, Z.; Kašpárková, V.; Humpolíček, P.; Ševčíková, P.; Stejskal, Jaroslav

    2013-01-01

    Roč. 67, č. 8 (2013), s. 1103-1108. ISSN 0366-6352 R&D Projects: GA ČR(CZ) GA13-08944S Institutional support: RVO:61389013 Keywords : polyaniline * silver * antibacterial properties Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.193, year: 2013

  18. Silver doped catalysts for treatment of exhaust

    Energy Technology Data Exchange (ETDEWEB)

    Park, Paul Worn (Peoria, IL); Hester, Virgil Raymond (Edelstein, IL); Ragle, Christie Susan (Havana, IL); Boyer, Carrie L. (Shiloh, IL)

    2009-06-02

    A method of making an exhaust treatment element includes washcoating a substrate with a slurry that includes a catalyst support material. At least some of the catalyst support material from the slurry may be transferred to the substrate, and silver metal (Ag) is dispersed within the catalyst support material.

  19. Synthesis and Study of Silver Nanoparticles

    Science.gov (United States)

    Soloman, Sally D.; Bahadory, Mozghan; Jeyarajasingam, Aravindan V.; Rutkowsky, Susan A.; Boritz, Charles; Mulfinger, Lorraine

    2007-01-01

    A laboratory experiment was conducted in which the students synthesized yellow colloidal silver, estimate particle size using visible spectroscopy and studied aggregation effects. The students were thus introduced to nanotechnology along with other topics such as redox chemistry, limiting and excess reactants, spectroscopy and atomic size.

  20. Anaerobic Toxicity of Cationic Silver Nanoparticles

    Science.gov (United States)

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag+ under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged p...

  1. Analytical Application of Silver Composite Electrode

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Kopanica, M.

    2002-01-01

    Roč. 32, č. 2 (2002), s. 153-166. ISSN 1040-8347 R&D Projects: GA ČR GA203/98/P239 Institutional research plan: CEZ:AV0Z4040901 Keywords : silver composite electrode * voltammetry * halogenides Subject RIV: CG - Electrochemistry Impact factor: 2.074, year: 2002

  2. Adsorbate-mediated growth of silver nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Šišková, K.; Vlčková, B.; Mojzeš, P.; Šlouf, Miroslav

    Praha : Czech Society for New Materials, Nanoscience and Nanotechnology Section, 2003. s. 19. ISBN 80-214-2486-9. [International Conference 'NANO'. 21.10.2003-23.10.2003, Brno] R&D Projects: GA ČR GA203/01/1013 Institutional research plan: CEZ:AV0Z4050913 Keywords : mediated growth * silver nanoparticles * nanotechnology Subject RIV: CF - Physical ; Theoretical Chemistry

  3. Effect of silver nanoparticles on concentration of silver heavy element and growth indexes in cucumber (Cucumis sativus L. negeen)

    International Nuclear Information System (INIS)

    The tremendous progress on nanoparticle research area has been made significant effects on the economy, society, and the environment. Silver nanoparticle is one of the most important particles in these categories. Silver nanoparticles can be converted to the heavy silver metal in water by oxidation. Moreover, in the high amounts of silver concentration, they will be accumulated in different parts of the plant. However, by changing the morphology of the plant, the production will be harmful for human consumptions. In this study, nano-powders with average 50 nm silver particles are mixed with deionized distilled water in a completely randomized design. Seven treatments with various concentrations of suspension silver nanoparticles were prepared and repeated in four different parts of the plant in a regular program of spraying. Samples were analyzed to study the growth indexes and concentration of silver in different parts of the plant. It was observed that with increasing concentration of silver nanoparticles on cucumber, the growth indexes (except pH fruit), and the concentration of silver heavy metal are increased significantly. The incremental concentration had the linear relationship with correlation coefficient 0.95 and an average of 0.617 PPM by increasing of each unit in one thousand concentration of nanosilver. Although, by increasing concentration of silver nanoparticles as spraying form, the plant morphological characteristics were improved, the concentration of silver heavy metal in various plant organs was increased. These results open a new pathway to consider the effect of nanoparticles on plant’s productions for human consumptions.

  4. Small Wind Turbine Applications: Current Practice in Colorado

    International Nuclear Information System (INIS)

    Numerous small wind turbines are being used by homeowners in Colorado. Some of these installations are quite recent while others date back to the federal tax-credit era of the early 1980s. Through visits with small wind turbine owners in Colorado, I have developed case studies of six small wind energy applications focusing on the wind turbine technology, wind turbine siting, the power systems and electric loads, regulatory issues, and motivations about wind energy. These case studies offer a glimpse into the current state-of-the-art of small-scale wind energy and provide some insight into issues affecting development of a wider market

  5. Preparation of starch-stabilized silver nanoparticles from amylose-sodium palmitate inclusion complexes

    Science.gov (United States)

    Starch-stabilized silver nanoparticles were prepared from amylose-sodium palmitate complexes by first converting sodium palmitate to silver palmitate by reaction with silver nitrate and then reducing the silver ion to metallic silver. This process produced water solutions that could be dried and the...

  6. A Debris Flow Chronology and Analysis of Controls on Debris Flow Occurrence in the Upper Colorado River Valley, Rocky Mountain National Park, CO

    Science.gov (United States)

    Grimsley, K. J.; Rathburn, S. L.; Grosicki, G.

    2011-12-01

    In high gradient environments, debris flows are commonly a dominant source of sediment transport and erosion. The importance of debris flows along the Upper Colorado was recently highlighted when the Grand Ditch, a 19th century water-conveyance ditch, overtopped from snowmelt and triggered a large debris flow along Lulu Creek, a tributary of the Upper Colorado River. Earlier research suggests that multiple debris flows have been triggered from the Grand Ditch over the last century, with higher magnitude and frequency than naturally occurring debris flows. To thoroughly test this hypothesis, debris flows are being mapped, dated using dendrogeomorphic evidence from tree cores and tree scars, and analyzed for relative magnitude. A total of approximately 15-20 mappable debris flows along the Upper Colorado have been located and sampled using a combination of historic aerial photos and field exploration in the basin. Berms observed along these debris flows are up to 1.5 meters high and frequently extend to the Colorado River valley bottom. Where even-aged stands are observed as a result of simultaneous stand germination after a debris flow, tree cores are collected from the oldest trees in the stand to estimate the age of the debris flow. Species of sampled trees include Lodgepole pine, Douglas fir, and Engelmann spruce. Initial core dates from a debris flow that extends along the Colorado River to just north of the Lulu wetland range from 29 to 37 years. Sampling of scarred survivor trees from debris flow berms provides an even better indicator of age because the warped tree rings can be counted to precisely date scarring events. Thus far 40 tree scars have been wedged and will be processed and dated during Fall 2011. Relative flow magnitudes will be compared using the heights of tree scars above the channel thalweg. Debris flow occurrence is related to the distribution of hydrothermally altered rocks in addition to other factors such as the aspect and gradient of the

  7. Nineteenth-century aether theories

    CERN Document Server

    Schaffner, Kenneth F

    2013-01-01

    Nineteenth-Century Aether Theories focuses on aether theories. The selection first offers information on the development of aether theories by taking into consideration the positions of Christiaan Huygens, Thomas Young, and Augustin Fresnel. The text then examines the elastic solid aether. Concerns include Green's aether theory, MacCullagh's aether theory, and Kelvin's aether theory. The text also reviews Lorentz' aether and electron theory. The development of Lorentz' ideas of the stagnant aether and electrons; Lorentz' theorem of corresponding states and its development; and Lorentz' respons

  8. Assessment of surface-water quantity and quality, Eagle River watershed, Colorado, 1947-2007

    Science.gov (United States)

    Williams, Cory A.; Moore, Jennifer L.; Richards, Rodney J.

    2011-01-01

    From the early mining days to the current tourism-based economy, the Eagle River watershed (ERW) in central Colorado has undergone a sequence of land-use changes that has affected the hydrology, habitat, and water quality of the area. In 2000, the USGS, in cooperation with the Colorado River Water Conservation District, Eagle County, Eagle River Water and Sanitation District, Upper Eagle Regional Water Authority, Colorado Department of Transportation, City of Aurora, Town of Eagle, Town of Gypsum, Town of Minturn, Town of Vail, Vail Resorts, City of Colorado Springs, Colorado Springs Utilities, and Denver Water, initiated a retrospective analysis of surface-water quantity and quality in the ERW.

  9. A physiologically based pharmacokinetic model for ionic silver and silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Bachler G

    2013-09-01

    Full Text Available Gerald Bachler, Natalie von Goetz, Konrad Hungerbühler ETH Zurich, Institute for Chemical and Bioengineering, Zurich, Switzerland Abstract: Silver is a strong antibiotic that is increasingly incorporated into consumer products as a bulk, salt, or nanosilver, thus potentially causing side-effects related to human exposure. However, the fate and behavior of (nanosilver in the human body is presently not well understood. In order to aggregate the existing experimental information, a physiologically based pharmacokinetic model (PBPK was developed in this study for ionic silver and nanosilver. The structure of the model was established on the basis of toxicokinetic data from intravenous studies. The number of calibrated parameters was minimized in order to enhance the predictive capability of the model. We validated the model structure for both silver forms by reproducing exposure conditions (dermal, oral, and inhalation of in vivo experiments and comparing simulated and experimentally assessed organ concentrations. Therefore, the percutaneous, intestinal, or pulmonary absorption fraction was estimated based on the blood silver concentration of the respective experimental data set. In all of the cases examined, the model could successfully predict the biodistribution of ionic silver and 15–150 nm silver nanoparticles, which were not coated with substances designed to prolong the circulatory time (eg, polyethylene glycol. Furthermore, the results of our model indicate that: (1 within the application domain of our model, the particle size and coating had a minor influence on the biodistribution; (2 in vivo, it is more likely that silver nanoparticles are directly stored as insoluble salt particles than dissolve into Ag+; and (3 compartments of the mononuclear phagocytic system play a minor role in exposure levels that are relevant for human consumers. We also give an example of how the model can be used in exposure and risk assessments based on five

  10. Promoting Equalization and Local Control in Financing Colorado's Schools.

    Science.gov (United States)

    Mathers, Judith K.; King, Richard A.

    1997-01-01

    Per-pupil property valuation extremes among Colorado school districts are as varied as the landscape. A foundation plan levels funding disparities for school operations, but financing of major capital outlay projects still depends on local property taxation. Funds are needed to finance classroom technologies and Internet connections. (MLH)

  11. Colorado Model Content Standards for Music: Suggested Grade Level Expectations.

    Science.gov (United States)

    Colorado State Dept. of Education, Denver.

    The state of Colorado has set forth five content standards for music education in its public schools: (1) students sing or play on instruments a varied repertoire of music, alone or with others; (2) students will read and notate music; (3) students will create music; (4) students will listen to, analyze, evaluate, and describe music; and (5)…

  12. Problem Based Learning at the University of Colorado at Denver.

    Science.gov (United States)

    Duffield, Judith A.; Grabinger, R. Scott

    This paper provides a brief overview of Problem-Based Learning (PBL) as an instructional methodology. A description of a graduate program for practicing teachers at the University of Colorado at Denver (UCD) is also included. Problem-based learning is a student-centered instructional methodology that teaches content and skills within a knowledge…

  13. Looking Forward: Colorado's Fiscal Prospects Amid a Financial Crisis

    Science.gov (United States)

    Buchanan, Wade, Ed.; Jones, Rich, Ed.; Watt, Joe, Ed

    2009-01-01

    This report projects the amount Colorado would need to spend to maintain state services at 2007 levels through fiscal year 2012-13 and the amount of revenues that will be generated to pay for them. The costs of services were estimated based on factors that drive the budget, such as the number of students in college, inflation rates and the number…

  14. 78 FR 62001 - Colorado Disaster Number CO-00066

    Science.gov (United States)

    2013-10-10

    ... ADMINISTRATION Colorado Disaster Number CO-00066 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1...: 06/24/2014. ADDRESSES: Submit completed loan applications to: U.S. Small Business Administration... CONTACT: A. Escobar, Office of Disaster Assistance, U.S. Small Business Administration, 409 3rd Street...

  15. 78 FR 62001 - Colorado Disaster Number CO-00065

    Science.gov (United States)

    2013-10-10

    ... ADMINISTRATION Colorado Disaster Number CO-00065 AGENCY: U.S. Small Business Administration. ACTION: Amendment 3... loan applications to: U.S. Small Business Administration, Processing and Disbursement Center, 14925... Assistance, U.S. Small Business Administration, 409 3rd Street SW., Suite 6050, Washington, DC...

  16. From Colorado to Guam: Infant Diagnostic Audiological Evaluations by Telepractice

    Science.gov (United States)

    Hayes, Deborah; Eclavea, Elaine; Dreith, Susan; Habte, Bereket

    2012-01-01

    This manuscript describes a pilot project in which infants in Guam who refer on newborn hearing screening receive diagnostic audiological evaluation conducted by audiologists in Colorado over the Internet (telepractice). The evaluation is completed in real time using commercially-available software and personal computers to control the diagnostic…

  17. The Colorado Gambling Boom: An Experiment in Rural Community Development.

    Science.gov (United States)

    Stokowski, Patricia A.

    1992-01-01

    Three small Colorado towns that faced a declining economy as the mining resource ran out used gambling-based tourism as a strategy for community development. Although economic benefits to the towns have far exceeded expectations, negative social, environmental, and political changes, such as crime alcoholism, traffic problems, and conflicts…

  18. 78 FR 60008 - Colorado Disaster Number CO-00065

    Science.gov (United States)

    2013-09-30

    ... ADMINISTRATION Colorado Disaster Number CO-00065 AGENCY: U.S. Small Business Administration. ACTION: Amendment 2... applications to: U.S. Small Business Administration, Processing And Disbursement Center, 14925 Kingsport Road.... Small Business Administration, 409 3rd Street SW., Suite 6050, Washington, DC 20416....

  19. The Colorado Plateau IV: shaping conservation through science and management

    Science.gov (United States)

    Wakeling, Brian F.; Sisk, Thomas D.

    2010-01-01

    Roughly centered on the Four Corners region of the southwestern United States, the Colorado Plateau covers some 130,000 square miles of sparsely vegetated plateaus, mesas, canyons, arches, and cliffs in Arizona, Utah, Colorado, and New Mexico. With elevations ranging from 3,000 to 14,000 feet, the natural systems found within the plateau are dramatically varied, from desert to alpine conditions. This book focuses on the integration of science and resource management issues in this unique and highly varied environment. Broken into three subsections, this volume addresses conservation biology, biophysical resources, and inventory and monitoring concerns. The chapters range in content, addressing conservation issues–past, present, and future–on the Colorado Plateau, measurement of human impacts on resources, grazing and wildland-urban interfaces, and tools and methods for monitoring habitats and species. An informative read for people interested in the conservation and natural history of the region, the book will also serve as a valuable reference for those people engaged in the management of cultural and biological resources of the Colorado Plateau, as well as scientists interested in methods and tools for land and resource management throughout the West.

  20. Telehealth: Families Finding Ways to Connect in Rural Colorado

    Science.gov (United States)

    Kaiser, Kristen

    2011-01-01

    JFK Partners, at the University of Colorado Denver, School of Medicine, is currently implementing a study on the use of telehealth (receiving treatment or services using videoconferencing technology, such as Skype) and youth with autism spectrum disorder (ASD) and anxiety. The study is an exploratory grant from Health Resources and Services…

  1. Small-Scale Spatial Variability of Ozone in Boulder, Colorado

    Science.gov (United States)

    Deanes, L. N.; Sadighi, K.; Casey, J. G.; Collier, A. M.; Hannigan, M.

    2015-12-01

    Surface ozone (O3) can pose several health risks to humans, such as an increased number of and intensity of asthma attacks. Considering this, it is important that ozone levels are monitored. While municipal air quality monitors are present in cities like Boulder, Colorado, these monitors often only consider regional analysis, neglecting the variability of compounds, such as ozone or carbon monoxide, over smaller distances. Small-scale (approximately 1 kilometer) spatial variability in ozone is important because humans experience these small scales on a daily basis. Using low-cost, next-generation air quality monitors ("pods") developed at the University of Colorado-Boulder, we assessed small-scale spatial variability of surface ozone in Boulder, Colorado. This was done by placing clusters of 4-5 pods within approximately 1 kilometer of each other at specific sites in the city of Boulder. We collected data at two sites: one on the University of Colorado-Boulder campus (i.e., an urban site) and one outside of the city (i.e., a rural site). Pods were left in their positions for one to two weeks allowing for observation of ozone trends. As expected the typical diurnal trend was observed; however, further analysis revealed differences between these daily trends. Data collected by the pods allows for better understanding of small-scale spatial variability of surface ozone and how this may be driven by nearby sources.

  2. Colorado Plateau magmatism and uplift by warming of heterogeneous lithosphere.

    Science.gov (United States)

    Roy, Mousumi; Jordan, Thomas H; Pederson, Joel

    2009-06-18

    The forces that drove rock uplift of the low-relief, high-elevation, tectonically stable Colorado Plateau are the subject of long-standing debate. While the adjacent Basin and Range province and Rio Grande rift province underwent Cenozoic shortening followed by extension, the plateau experienced approximately 2 km of rock uplift without significant internal deformation. Here we propose that warming of the thicker, more iron-depleted Colorado Plateau lithosphere over 35-40 Myr following mid-Cenozoic removal of the Farallon plate from beneath North America is the primary mechanism driving rock uplift. In our model, conductive re-equilibration not only explains the rock uplift of the plateau, but also provides a robust geodynamic interpretation of observed contrasts between the Colorado Plateau margins and the plateau interior. In particular, the model matches the encroachment of Cenozoic magmatism from the margins towards the plateau interior at rates of 3-6 km Myr(-1) and is consistent with lower seismic velocities and more negative Bouguer gravity at the margins than in the plateau interior. We suggest that warming of heterogeneous lithosphere is a powerful mechanism for driving epeirogenic rock uplift of the Colorado Plateau and may be of general importance in plate-interior settings. PMID:19536263

  3. 'Pot Tourists' Linked to Surge in Colorado ER Visits

    Science.gov (United States)

    ... pot is so well-known, Hill said, that tourism boards have taken out billboards that say, "Don't let a candy bar ruin your vacation. With edibles, start low and go slow." The Colorado Legislature also has pumped more ...

  4. 77 FR 40630 - Notice of Competitive Coal Lease Sale, Colorado

    Science.gov (United States)

    2012-07-10

    ... Bureau of Land Management Notice of Competitive Coal Lease Sale, Colorado AGENCY: Bureau of Land Management, Interior. ACTION: Notice of competitive coal lease sale. SUMMARY: Notice is hereby given that... competitive lease by sealed bid in accordance with the provisions of the Mineral Leasing Act of 1920,...

  5. A CENTURY OF NEWS DISCOURSE

    Directory of Open Access Journals (Sweden)

    Allan Bell

    2003-05-01

    Full Text Available This paper traces the development of news discourse across the 20th century ihrough a case study ofthe coverage of three expeditions to the South Pole: Captain Scott in 1912, Sir Edmund Hillary in 1958, and Peter Hillary in 1999. The way the news about the three expeditions reached New Zealand media serves as a framework and an illustration to examine three related issues: how technology has changed the time and place dimensions of news delivery; the consequent and concomitant shifts in news presentation; and associated changes in how humans have understood time and place. News values remain the same at a broad level across the century, but different in detail. Nationalism is obtrusive, but its focus shifts. In news practice, the deadline and the scoop drive the news in al1 three periods, but the scooping medium shifts from press to radio to television. The lapse between an event and its reporting shrinks exponentially from months to hours to minutes. The design of newspaper front pages changes radically, and news language compresses. There are social impacts, with newsworthy figures receiving closer exposure and the audience being cast in a more voyeuristic role.

  6. REVIEW: A CENTURY OF PROTESTS

    Directory of Open Access Journals (Sweden)

    Uday Chandra

    2015-03-01

    Full Text Available Review of: Arupjyoti Saikia. 2013. A Century of Protests: Peasant Politics in Assam Since 1900. New Delhi and Abingdon: Routledge. Notwithstanding its somewhat misleading subtitle, A Century of Protests is a painstaking reconstruction of the checkered agrarian history of the Brahmaputra Valley between the passage of the Assam Land Revenue Regulation of 1886 and the repeal of the Assam Tenancy Act of 1971 in 1986. The state of Assam in India today, bordering what is now Bangladesh, lies beneath the watchful eyes of the Eastern Himalayas, through which the mighty Brahmaputra gushes and breathes life into the valley. The landscape of the Brahmaputra Valley, historically speaking, has been as much a patchwork of field and forest as of different ethnolinguistic and religious groups, ever fluid and shifting in response to human and non-human vectors of change. The contested relations of power that yoke together owners and cultivators of this complex, variegated landscape in the late colonial and early postcolonial eras is the subject of the book under review.

  7. Comparative Assessment of Antimicrobial Efficiency of Ionic Silver, Silver Monoxide, and Metallic Silver Incorporated onto an Aluminum Oxide Nanopowder Carrier

    International Nuclear Information System (INIS)

    The present paper provides comparative assessment of antimicrobial efficiency of ionic silver (Ag+), silver monoxide (Ag2O), and metallic silver (Ag) incorporated onto an aluminum oxide nanopowder carrier (Al2O3). The deposition of Ag+ ions, Ag2O nanoparticles, and Ag nanoparticles on an different phases of aluminum oxide nanopowder carrier was realized using consecutive stages of dry sol-gel method. The Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders were widely characterized qualitatively and quantitatively by SEM, physical nitrogen sorption and XRD analyses. Results indicate that the Al2O3 nanopowders added with Ag+, Ag2O, and Ag, apart from phase composition, were not differing considerably from one another in terms of their morphology and physical properties. However, nanopowders of Al2O3-Ag were more agglomerated than Al2O3-Ag2O and Al2O3-Ag+ nanopowders. The antibacterial activity of the nanopowders was examined by the spread plate method using bacterial strains such as Escherichia coli, Sarcina lutea, and Bacillus subtilis. The best antibacterial properties against Sarcina lutea strain were achieved in the amorphous-Al2O3-Ag+ and Al2O3-Ag2O nanopowders, whereas the worst antimicrobial activity against Bacillus subtilis and Escherichia coli was shown by the Al2O3-Ag+ and Al2O3-Ag nanopowders. The observed increase of the antibacterial activity as the silver content was not however significant for Al2O3-Ag nanopowders. The results obtained in the present experiments show that the Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders, possessing good bactericidal properties, can be produced by using consecutive stages of dry sol-gel method, and Al2O3 nanopowder added with Ag2O is considered as the best raw material in the production of antiseptic materials.

  8. Femtosecond laser structuring of silver-containing glass: Silver redistribution, selective etching, and surface topology engineering

    International Nuclear Information System (INIS)

    Femtosecond direct laser writing in silver-containing phosphate glasses allows for the three-dimensional (3D) implementation of complex photonic structures. Sample translation along or perpendicular to the direction of the beam propagation has been performed, which led to the permanent formation of fluorescent structures, either corresponding to a tubular shape or to two parallel planes at the vicinity of the interaction voxel, respectively. These optical features are related to significant modifications of the local material chemistry. Indeed, silver depletion areas with a diameter below 200 nm were evidenced at the center of the photo-produced structures while photo-produced luminescence properties are attributed to the formation of silver clusters around the multiphoton interaction voxel. The laser-triggered oxidation-reduction processes and the associated photo-induced silver redistribution are proposed to be at the origin of the observed original 3D luminescent structures. Thanks to such material structuring, surface engineering has been also demonstrated. Selective surface chemical etching of the glass has been obtained subsequently to laser writing at the location of the photo-produced structures, revealing features with nanometric depth profiles and radial dimensions strongly related to the spatial distributions of the silver clusters

  9. Femtosecond laser structuring of silver-containing glass: Silver redistribution, selective etching, and surface topology engineering

    Energy Technology Data Exchange (ETDEWEB)

    Desmoulin, Jean-Charles; Petit, Yannick; Cardinal, Thierry, E-mail: thierry.cardinal@icmcb.cnrs.fr [CNRS, ICMCB, UPR 9048, F-33600 Pessac, France and Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Canioni, Lionel [Université Bordeaux, Centre Lasers Intenses et Applications–UMR 5107 CNRS, 351 cours de la Libération, 33405 Talence Cedex (France); Dussauze, Marc [Université de Bordeaux, Institut des Sciences Moléculaires, CNRS UMR 5255, 351 cours de la Libération, 33405 Talence Cedex (France); Lahaye, Michel [Université de Bordeaux, Placamat, avenue Docteur Albert Schweitzer, 33608 Pessac Cedex (France); Gonzalez, Hernando Magallanes; Brasselet, Etienne [Université Bordeaux, Laboratoire Ondes et Matière d' Aquitaine–UMR 5798, CNRS, 351 cours de la Libération, 33405 Talence Cedex (France)

    2015-12-07

    Femtosecond direct laser writing in silver-containing phosphate glasses allows for the three-dimensional (3D) implementation of complex photonic structures. Sample translation along or perpendicular to the direction of the beam propagation has been performed, which led to the permanent formation of fluorescent structures, either corresponding to a tubular shape or to two parallel planes at the vicinity of the interaction voxel, respectively. These optical features are related to significant modifications of the local material chemistry. Indeed, silver depletion areas with a diameter below 200 nm were evidenced at the center of the photo-produced structures while photo-produced luminescence properties are attributed to the formation of silver clusters around the multiphoton interaction voxel. The laser-triggered oxidation-reduction processes and the associated photo-induced silver redistribution are proposed to be at the origin of the observed original 3D luminescent structures. Thanks to such material structuring, surface engineering has been also demonstrated. Selective surface chemical etching of the glass has been obtained subsequently to laser writing at the location of the photo-produced structures, revealing features with nanometric depth profiles and radial dimensions strongly related to the spatial distributions of the silver clusters.

  10. Microwave-assisted green synthesis of silver nanoparticles by carboxymethyl cellulose sodium and silver nitrate

    International Nuclear Information System (INIS)

    In the present work, silver nanoparticles are prepared by a simple green method. Carboxymethyl cellulose sodium (CMS) is employed to work as both a reducing and a stabilizing reagent in the reaction. Although the hydrolysis of CMS in aqueous solution without the help of catalyst is nearly impossible using conventional heating method, our experimental results show that it can be achieved when the reactive system is radiated by microwave. Consequently, silver ion can be reduced by the hydrolyzate of CMS to form silver nanoparticles. Further studies reveal that CMS with a high concentration will lead to high reactive speed and big particles, however, the inborn silver nanoparticles will be smaller when the CMS concentration is higher than 0.04% for 0.1 mM AgNO3. Experimental results have also shown that the concentration of CMS has very small effect on the size distribution, whereas the impact of AgNO3 concentration is obvious. AgNO3 with high concentration will result in big particle and broad size distribution in this reaction. The silver nanoparticles prepared in this way are uniform and stable, which can be stored at room temperature for 2 months without any visible change

  11. In Vivo Toxicity of Silver Nanoparticles and Silver Ions in Zebrafish (Danio rerio

    Directory of Open Access Journals (Sweden)

    Katrine Bilberg

    2012-01-01

    Full Text Available The influence of water chemistry on characterised polyvinyl pyrrolidone- (PVP- coated silver nanoparticles (81 nm was investigated. NaCl solution series of 100–800 mg L−1 lead to initial and temporal increase in nanoparticles size, but agglomeration was limited. pH variation (5–8 had only minor influence on the hydrodynamic particle size. Acute toxicity of nanosivler to zebrafish (Danio rerio was investigated in a 48-hour static renewal study and compared with the toxicity of silver ions (AgNO3. The nanosilver and silver ion 48-hour median lethal concentration (LC50 values were 84 μg L−1 and 25 μg L−1, respectively. To investigate exposure-related stress, the fish behaviour was observed visually after 0, 3, 6, 12, 24, 27, 30, and 48 hours of both nanosilver and ionic silver treatments. These observations revealed increased rate of operculum movement and surface respiration after nanosilver exposure, suggesting respiratory toxicity. The present study demonstrates that silver nanoparticles are lethal to zebrafish.

  12. Colorado River Basin Water Supply and Demand Study

    Science.gov (United States)

    Prairie, J. R.; Jerla, C.

    2012-12-01

    The Colorado River Basin Water Supply & Demand Study (Study), part of the Basin Study Program under the Department of the Interior's WaterSMART Program, is being conducted by the Bureau of Reclamation and agencies representing the seven Colorado River Basin States. The purpose of the Study is to assess future water supply and demand imbalances in the Colorado River Basin over the next 50 years and develop and evaluate options and strategies to resolve those imbalances. The Study is being conducted over the period from January 2010 to September 2012 and contains four major phases: Water Supply Assessment, Water Demand Assessment, System Reliability Analysis, and Development and Evaluation of Opportunities for balancing supply and demand. To address the considerable amount of uncertainty in projecting the future state of the Colorado River system, the Study has adopted a scenario planning approach that has resulted in four water supply scenarios and up to six water demand scenarios. The water supply scenarios consider hydrologic futures derived from the observed historical and paleo-reconstructed records as well as downscaled global climate model (GCM) projections. The water demand scenarios contain differing projections of parameters such as population growth, water use efficiency, irrigated acreage, and water use for energy that result in varying projections of future demand. Demand for outdoor municipal uses as well as agricultural uses were adjusted based on changing rates of evapotranspiration derived from downscaled GCM projections. Water supply and demand scenarios are combined through Reclamation's long-term planning model to project the effects of future supply and demand imbalances on Colorado River Basin resources. These projections lend to an assessment of the effectiveness of a broad range of options and strategies to address future imbalances.

  13. Synthesis and characterization of silver molybdate nanowires, nanorods and multipods

    Indian Academy of Sciences (India)

    G Nagaraju; G T Chandrappa; Jacques Livage

    2008-06-01

    Silver molybdate nanowires, nanorods and multipods like structures have been prepared by an organic free hydrothermal process using ammonium molybdate and silver nitrate solutions. The powder X-ray diffraction (PXRD) patterns reveal that the silver molybdate belongs to anorthic structure. The thickness, 200–500 nm, for silver molybdate nanorods/wires and 2–5 m for microrods are identified from SEM images. UV-visible spectrum of silver molybdate nanorods/nanowires shows maximum absorbance at 408 nm. Photoluminescence (PL) spectrum exhibits UV emission at 335 nm, violet emission at 408 nm and a weak green emission at 540 nm. The influence of hydrothermal synthesis conditions on silver molybdate nanowires, nanorods and multipods compositions were established.

  14. Biosynthesis of Silver Nano Particles from Fusarium oxysporum Culture

    Directory of Open Access Journals (Sweden)

    Rita Singh Majumdara

    2015-12-01

    Full Text Available From a very long time inhibitory effect of silver has been recognized and used towards many bacterial strains and microorganisms commonly present in medical and industrial processes. The most useful and important characteristic of silver is its antimicrobial property. In the current study silver nano particles with uniform size distribution of 10-20nm with stability and promising increase in yield were obtained and effect of cultural and physical conditions on biological synthesis of SNPs was studied. SNPs (Silver Nanoparticles synthesis was first analysed out by visual observation of colour change of the fungal filtrate after treatment with silver nitrate (AgNO3 solution within 24hrs. Formation of dark brown colour of fungal cell filtrate indicated the presence of SNPs (Silver Nanoparticles.

  15. Silver nanoparticles-coated glass frits for silicon solar cells

    Science.gov (United States)

    Li, Yingfen; Gan, Weiping; Li, Biyuan

    2016-04-01

    Silver nanoparticles-coated glass frit composite powders for silicon solar cells were prepared by electroless plating. Silver colloids were used as the activating agent of glass frits. The products were characterized by X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. The characterization results indicated that silver nanoparticles with the melting temperature of 838 °C were uniformly deposited on glass frit surface. The particle size of silver nanoparticles could be controlled by adjusting the [Ag(NH3)2]NO3 concentration. The as-prepared composite powders were applied in the front side metallization of silicon solar cells. Compared with those based on pure glass frits, the solar cells containing the composite powders had the denser silver electrodes and the better silver-silicon ohmic contacts. Furthermore, the photovoltaic performances of solar cells were improved after the electroless plating.

  16. Surface Phenomena at Silver Nanoparticles in the Context of Toxicology

    DEFF Research Database (Denmark)

    Miclaus, Teodora

    2015-01-01

    associated with engineered nanomaterials. Among these materials, silver nanoparticles are some of the most widely employed and thus represent a major point of focus in nanotoxicology and the topic of this PhD thesis. While nanoparticles have, upon synthesis, well-defined characteristics, specific for their...... of nanotoxicology. The main aim of this PhD research is to investigate these phenomena at the surface of silver nanoparticles under conditions that are relevant for in vitro studies in order to understand their implications for nano-silver toxicity. Upon contact with biological fluids, particles get...... nanometre size silver sulphide particles in close proximity to the silver nanoparticle surface, as shown in the second study. The identification of spontaneous sulfidation under in vitro settings is a novel finding with important implications for toxicity, as Ag2S traps toxic silver ions into an insoluble...

  17. Toxicity of silver nanoparticles in monocytes and keratinocytes

    DEFF Research Database (Denmark)

    Orłowski, Piotr; Krzyzowska, Malgorzata; Winnicka, Anna;

    2012-01-01

    Silver nanoparticles are of interest to be used as antimicrobial agents in wound dressings and coatings in medical devices, but potential adverse effects have been reported in the literature. The possible local inflammatory response to silver nanoparticles and the role of cell death in determining...... these effects are largely unknown. Effects of the mixture of silver nanoparticles of different sizes were compared in in vitro assays for cytotoxicity, caspase-1 and caspase-9 activity and bax expression. In all tested concentrations, silver nanoparticles were more toxic for RAW 264.7 monocytes than for...... 291.03C keratinocytes and induced significant caspase-1 activity and necrotic cell death. In keratinocytes, more significantly than in macrophages, silver nanoparticles led to increase of caspase-9 activity and apoptosis. These results indicate that effects of silver nanoparticles depend on the type...

  18. Preparation of hollow silver microspheres and their characterization

    International Nuclear Information System (INIS)

    Hollow silver microspheres have been prepared using modified polystyrene microspheres as hard template. The process of preparation is as follows: polystyrene microspheres with a layer of silver coated on their surface by the chemical planting method were dissolved in tetrahydrofuran, then the hollow silver microspheres were prepared. The properties of silver microspheres were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The optical properties of silver microspheres were studied using UV-Vis spectrophotometer. The inside diameter of silver hollow microspheres is 250 nm, the shell thickness is 15 nm, and the absorption peak of nanoparticles can red-shift from 600 nm to 900 nm at the range of UV-Vis spectra. These routes realize a facile method that tuning of the absorption band of Ag nanostructures within the visible-near-infrared region. (authors)

  19. 75 FR 49487 - Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray

    Science.gov (United States)

    2010-08-13

    ... AGENCY Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray AGENCY: Environmental Protection... period for the draft document ``Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray'' (EPA.... ] ADDRESSES: The draft ``Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray'' is...

  20. Ark and Archive: Making a Place for Long-Term Research on Barro Colorado Island, Panama.

    Science.gov (United States)

    Raby, Megan

    2015-12-01

    Barro Colorado Island (BCI), Panama, may be the most studied tropical forest in the world. A 1,560-hectare island created by the flooding of the Panama Canal, BCI became a nature reserve and biological research station in 1923. Contemporaries saw the island as an "ark" preserving a sample of primeval tropical nature for scientific study. BCI was not simply "set aside," however. The project of making it a place for science significantly reshaped the island through the twentieth century. This essay demonstrates that BCI was constructed specifically to allow long-term observation of tropical organisms--their complex behaviors, life histories, population dynamics, and changing species composition. An evolving system of monitoring and information technology transformed the island into a living scientific "archive," in which the landscape became both an object and a repository of scientific knowledge. As a research site, BCI enabled a long-term, place-based form of collective empiricism, focused on the study of the ecology of a single tropical island. This essay articulates tropical ecology as a "science of the archive" in order to examine the origins of practices of environmental surveillance that have become central to debates about global change and conservation. PMID:27024937

  1. Economic impact study of the Uranium Mill Tailings Remedial Action Project in Colorado: Colorado state fiscal year 1994

    Energy Technology Data Exchange (ETDEWEB)

    1994-11-01

    The Colorado economic impact study summarizes employment and economic benefits to the state from activities associated with the Uranium Mill Tailings Remedial Action (UMTRA) Project during Colorado state fiscal year 1994. To capture employment information, a questionnaire was distributed to subcontractor employees at the active UMTRA Project sites of Grand Junction, Naturita, Gunnison, and Rifle, Colorado. Economic data were requested from each site prime subcontractor, as well as from the Remedial Action Contractor. The most significant benefits associated with the UMTRA Project in Colorado are summarized. This study assesses benefits associated with the Grand Junction, Gunnison, Naturita, and Rifle UMTRA Projects sites for the 1-year period under study. Work at the Naturita site was initiated in April 1994 and involved demolition of buildings at the processing site. Actual start-up of remediation of Naturita is planned to begin in the spring of 1995. Work at the Slick Rock and Maybell sites is expected to begin in 1995. The only current economic benefits associated with these sites are related to UMTRA Project support work.

  2. Economic impact study of the Uranium Mill Tailings Remedial Action Project in Colorado: Colorado state fiscal year 1994

    International Nuclear Information System (INIS)

    The Colorado economic impact study summarizes employment and economic benefits to the state from activities associated with the Uranium Mill Tailings Remedial Action (UMTRA) Project during Colorado state fiscal year 1994. To capture employment information, a questionnaire was distributed to subcontractor employees at the active UMTRA Project sites of Grand Junction, Naturita, Gunnison, and Rifle, Colorado. Economic data were requested from each site prime subcontractor, as well as from the Remedial Action Contractor. The most significant benefits associated with the UMTRA Project in Colorado are summarized. This study assesses benefits associated with the Grand Junction, Gunnison, Naturita, and Rifle UMTRA Projects sites for the 1-year period under study. Work at the Naturita site was initiated in April 1994 and involved demolition of buildings at the processing site. Actual start-up of remediation of Naturita is planned to begin in the spring of 1995. Work at the Slick Rock and Maybell sites is expected to begin in 1995. The only current economic benefits associated with these sites are related to UMTRA Project support work

  3. Bioleaching of a manganese and silver Ore

    International Nuclear Information System (INIS)

    The bioleaching with a strain of Thiobacillus thiooxidans of the ore of Farallon Negro (Catamarca, Argentina) was studied in order to estimate its application to the solution and recovery of the manganese, and to improve the silver extraction. The State company which works the mine has not yet found an economical process to extract the manganese and has only reached a 30% efficiency in the recovery of silver by cianuration. The effects of pulp density variations and the addition of different quantities of FeS were analysed looking for the best working conditions. 74 μm (mesh Tyler 200) of ore particles were used because that is the size used in this plant for the cianuration process. (Author)

  4. Standard specification for silvered flat glass mirror

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This specification covers the requirements for silvered flat glass mirrors of rectangular shape supplied as cut sizes, stock sheets or as lehr ends and to which no further processing (such as edgework or other fabrication) has been done. 1.2 This specification covers the quality requirements of silvered annealed monolithic clear and tinted flat glass mirrors up to 6 mm (¼ in.) thick. The mirrors are intended to be used indoors for mirror glazing, for components of decorative accessories or for similar uses. 1.3 This specification does not address safety glazing materials nor requirements for mirror applications. Consult model building codes and other applicable standards for safety glazing applications. 1.4 Mirrors covered in this specification are not intended for use in environments where high humidity or airborne corrosion promoters, or both, are consistently present (such as swimming pool areas, ocean-going vessels, chemical laboratories and other corrosive environments). 1.5 The dimensional val...

  5. Mycosynthesis of silver nanoparticles bearing antibacterial activity.

    Science.gov (United States)

    Azmath, Pasha; Baker, Syed; Rakshith, Devaraju; Satish, Sreedharamurthy

    2016-03-01

    Mycosynthesis of silver nanoparticles was achieved by endophytic Colletotrichum sp. ALF2-6 inhabiting Andrographis paniculata. Well dispersed nanoparticles were characterized using UV-Visible spectrometry with maximum absorption conferring at 420 nm. FTIR analysis revealed possible biomolecules reducing the metal salt and stabilization of nanoparticles. XRD analysis depicted the diffraction intensities exhibiting between 20 and 80 °C at 2theta angle thus conferring the crystalline nature of nanoparticles. Morphological characteristic using TEM revealed the polydispersity of nanoparticles with size ranging from 20 to 50 nm. Synthesized nanoparticles exhibited bactericidal activity against selected human pathogens. Nanoparticles mode of action was carried out to reveal DNA damage activity. Thus the present investigation reports facile fabrication of silver nanoparticles from endophytic fungi. PMID:27013906

  6. Silver transport in H-451 graphite

    International Nuclear Information System (INIS)

    Diffusion profiles have been measured for silver in hollow and solid cylinders in the temperature range 490 to 8000C. The profiles show two components of diffusion. There is a high concentration, relatively immobile zone near the surface and a low concentration, rapidly moving component deeper into the sample. The rapid component is well fitted by the diffusion equation when irreversible trapping is assumed. The diffusion coefficients determined by least-square analysis of the profiles can be represented by D (m2/sec) = 17.4 exp (-22,100/T). Excessive scatter was seen in the trapping coefficients determined from the profiles. This is believed to be due to varying amounts of impurities in the different samples. A limited number of desorption measurements were performed for silver from H-451 graphite. Evidence of Elovich-type behavior was noted

  7. Silver Nanoparticles in Alveolar Bone Surgery Devices

    Directory of Open Access Journals (Sweden)

    Stefano Sivolella

    2012-01-01

    Full Text Available Silver (Ag ions have well-known antimicrobial properties and have been applied as nanostrategies in many medical and surgical fields, including dentistry. The use of silver nanoparticles (Ag NPs may be an option for reducing bacterial adhesion to dental implant surfaces and preventing biofilm formation, containing the risk of peri-implant infections. Modifying the structure or surface of bone grafts and membranes with Ag NPs may also prevent the risk of contamination and infection that are common when alveolar bone augmentation techniques are used. On the other hand, Ag NPs have revealed some toxic effects on cells in vitro and in vivo in animal studies. In this setting, the aim of the present paper is to summarize the principle behind Ag NP-based devices and their clinical applications in alveolar bone and dental implant surgery.

  8. Effect of Accelerator in Green Synthesis of Silver Nanoparticles

    OpenAIRE

    Kamyar Shameli; Nor Azowa Ibrahim; Abdul Halim Abdullah; Mansor Bin Ahmad; Majid Darroudi

    2010-01-01

    Silver nanoparticles (Ag-NPs) were successfully synthesized in the natural polymeric matrix. Silver nitrate, gelatin, glucose, and sodium hydroxide have been used as silver precursor, stabilizer, reducing agent, and accelerator reagent, respectively. This study investigated the role of NaOH as the accelerator. The resultant products have been confirmed to be Ag-NPs using powder X-ray diffraction (PXRD), UV-vis spectroscopy, and transmission electron microscopy (TEM). The colloidal sols of Ag-...

  9. Self-supported silver nanoparticles containing bacterial cellulose membranes

    International Nuclear Information System (INIS)

    Hydrated bacterial cellulose (BC) membranes obtained from cultures of Acetobacter xylinum were used in the preparation of silver nanoparticles containing cellulose membranes. In situ preparation of Ag nanoparticles was achieved from the hydrolytic decomposition of silver triethanolamine (TEA) complexes. Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns both lead to the observation of spherical metallic silver particles with mean diameter of 8 nm well adsorbed onto the BC fibriles

  10. Self-supported silver nanoparticles containing bacterial cellulose membranes

    Energy Technology Data Exchange (ETDEWEB)

    Barud, Hernane S.; Barrios, Celina; Regiani, Thais; Marques, Rodrigo F.C. [Institute of Chemistry-UNESP, CP 355, Zip 14801-970, Araraquara, SP, 14801-970 (Brazil); Verelst, Marc; Dexpert-Ghys, Jeannette [Centre d' Elaboration de Materiaux et d' Etudes Structurales, CEMES, UPR No. 8011 - Universite Toulouse III, B.P. 94347, 29 rue Jeanne Marvig, 31055 Toulouse Cedex (France); Messaddeq, Younes [Institute of Chemistry-UNESP, CP 355, Zip 14801-970, Araraquara, SP, 14801-970 (Brazil); Ribeiro, Sidney J.L. [Institute of Chemistry-UNESP, CP 355, Zip 14801-970, Araraquara, SP, 14801-970 (Brazil)], E-mail: sidney@iq.unesp.br

    2008-05-01

    Hydrated bacterial cellulose (BC) membranes obtained from cultures of Acetobacter xylinum were used in the preparation of silver nanoparticles containing cellulose membranes. In situ preparation of Ag nanoparticles was achieved from the hydrolytic decomposition of silver triethanolamine (TEA) complexes. Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns both lead to the observation of spherical metallic silver particles with mean diameter of 8 nm well adsorbed onto the BC fibriles.

  11. Silver-functionalized carbon nanofiber composite electrodes for ibuprofen detection

    OpenAIRE

    Manea, F.; Motoc, S.; Pop, A.(National Institute for Physics and Nuclear Engineering, Bucharest, Romania); Remes, A.; Schoonman, J.

    2012-01-01

    The aim of this study is to prepare and characterize two types of silver-functionalized carbon nanofiber (CNF) composite electrodes, i.e., silver-decorated CNF-epoxy and silver-modified natural zeolite-CNF-epoxy composite electrodes suitable for ibuprofen detection in aqueous solution. Ag carbon nanotube composite electrode exhibited the best electroanalytical parameters through applying preconcentration/differential-pulsed voltammetry scheme.

  12. Characterizations of silver alloys used in modern Mexican coins

    International Nuclear Information System (INIS)

    This paper presents a complete methodology for the characterization of silver alloys used in modern coin production. Mexican coins with a nominal silver concentration from 10% to 99.99% were used in this study. Calibrated Glow Discharge Optical Emission Spectrometers were used to determine the chemical composition of the alloys as a function of the depth, while inductively coupled plasma was used to determine the total element composition in bulk. Scanning Electron Microscope was used to study the phase distributions in the different silver coins. According to Glow Discharge Optical Emission Spectrometers and inductively coupled plasma, the silver content found in the studied samples was consistently greater than that of the nominal silver content reported by the Mexican mint. This may lead to a review of the new methods of analysis used nowadays in contemporary coin minting. This result is very important because silver is increasing in value as metal and, considering the volume of production of silver coins, this may increase further as a consequence of a growing popular confidence in silver currency. In the case of silver studies, an advantage of the absence of silver detector in the Glow Discharge Optical Emission Spectrometers system is that it allows for the recalibration to have a better range of detection of other metals present in the alloys. A calibration curve using the copper content obtained by inductively coupled plasma (bulk) and Glow Discharge Optical Emission Spectrometers (depth profile) was performed. The relevance of control in modern silver coin minting was clarified, especially in minimizing the discrepancy between the nominal and the core fineness. The physical and chemical properties of the alloys studied are defined, revealing important variations in silver and copper contents. A new methodology and metrology for the control of coinage are suggested.

  13. Sonochemical Synthesis of Silver Nanoparticles Using Starch: A Comparison

    OpenAIRE

    Brajesh Kumar; Kumari Smita; Luis Cumbal; Alexis Debut; Ravinandan Nath Pathak

    2014-01-01

    A novel approach was applied to synthesize silver nanoparticles using starch under sonication. Colloidal silver nanoparticles solution exhibited an increase of absorption from 420 to 440 nm with increase starch quantity. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of spherical, polydispersed, amorphous, silver nanoparticles of diameter ranging from 23 to 97 nm with mean particle size of 45.6 nm. Selected area electro...

  14. Physicochemical and Atomic Characterization of Silver Powder after Biofield Treatment

    OpenAIRE

    Trivedi, Mahendra Kumar

    2015-01-01

    Silver is widely utilized as antimicrobial agent and wound dressing, where its shape, size, surface area, and surface charge play an important role. The aim of present study was to evaluate the impact of biofield treatment on physicochemical and atomic properties of silver powder. The silver powder was divided into two groups, coded as control and treatment. The treatment group received Mr. Trivedi’s biofield treatment. Subsequently, control and treated samples were characterized using ...

  15. Nanometer Sized Silver Particles Embedded Silica Particles—Spray Method

    OpenAIRE

    Karunagaran B; Nimma Elizabeth R.; Gnana kumar G; Nahm KeeSuk

    2009-01-01

    Abstract Spherical shaped, nanometer to micro meter sized silica particles were prepared in a homogeneous nature by spray technique. Silver nanoparticles were produced over the surface of the silica grains in a harmonized manner. The size of silver and silica particles was effectively controlled by the precursors and catalysts. The electrostatic repulsion among the silica spheres and the electro static attraction between silica spheres and silver particles make the synchronized structure of t...

  16. Glycidyl-methacrylate-based electrospun mats and catalytic silver nanoparticles

    OpenAIRE

    Demir, Mustafa Muammer; Uğur, Gökçe; Ugur, Gokce; Gülgün, Mehmet Ali; Gulgun, Mehmet Ali; Menceloğlu, Yusuf Z.; Menceloglu, Yusuf Z.

    2008-01-01

    P(AN-GMA) and PGMA fibers coated with monodisperse silver nanoparticles have been prepared by a combination of electrospinning and electroless plating. The morphology of the electrospun fibers remains unchanged after surface hydrazination. Oxidation of hydrazine in an ammoniacal solution of AgNO3 reduces and deposits silver atoms along the fiber surface, which then coalesce to Ag particles. The size of the silver nanoparticles is varied between 20-60 nm. Since the density of the active sites ...

  17. Antimicrobial Bacterial Cellulose-Silver Nanoparticles Composite Membranes

    OpenAIRE

    Barud, Hernane S.; Thaís Regiani; Rodrigo F. C. Marques; Wilton R. Lustri; Younes Messaddeq; Ribeiro, Sidney J.L.

    2011-01-01

    Antimicrobial bacterial cellulose-silver nanoparticles composite membranes have been obtained by “in situ” preparation of Ag nanoparticles from hydrolytic decomposition of silver nitrate solution using triethanolamine as reducing and complexing agent. The formation of silver nanoparticles was evidenced by the X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and absorption in the UV-Visible (350 nm to 600 nm). Thermal and mechanical properties toge...

  18. Solar induced growth of silver nanocrystals

    OpenAIRE

    Thøgersen, Annett; Muntingh, Georg

    2012-01-01

    The effect of solar irradiation on plasmonic silver nanocrystals has been investigated using Transmission Electron Microscopy and size distribution analysis, in the context of solar cell applications for light harvesting. Starting from an initial collection of spherical nanocrystals on a carbon film whose sizes are log-normally distributed, solar irradiation causes the nanocrystals to grow, with one particle reaching a diameter of 638 nm after four hours of irradiation. In addition some of th...

  19. Lactobacillus Mediated Synthesis of Silver Oxide Nanoparticles

    OpenAIRE

    Dhoondia, Zuzer H.; Hemlatta Chakraborty

    2012-01-01

    The ability of prokaryotic microorganisms to reduce the inorganic metals has opened up an exciting eco‐friendly approach towards the development of natural ‘nano‐factories’. However, a number of issues have to be addressed from the nanotechnological and microbiological point of view before such a biosynthesis approach can compete with the existing physical and chemical methods. This report investigates the synthesis of silver oxide nanoparticles using Lactobacillus mindensis, isolated using f...

  20. Gap plasmonics of silver nanocube dimers

    Science.gov (United States)

    Knebl, Dario; Hörl, Anton; Trügler, Andreas; Kern, Johannes; Krenn, Joachim R.; Puschnig, Peter; Hohenester, Ulrich

    2016-02-01

    We theoretically investigate gap plasmons for two silver nanocubes coupled through a molecular tunnel junction. In the absence of tunneling, the redshift of the bonding mode saturates with decreasing gap distance. Tunneling at small gap distances leads to a damping and slight blueshift of the bonding mode, but no low-energy charge transfer plasmon mode appears in the spectra. This finding is in stark contrast to recent work of Tan et al. [Science 343, 1496 (2014), 10.1126/science.1248797].

  1. Gap plasmonics of silver nanocube dimers

    OpenAIRE

    Knebl, Dario; Hörl, Anton; Trügler, Andreas; Kern, Johannes; Krenn, Joachim R.; Puschnig, Peter; Hohenester, Ulrich

    2016-01-01

    We theoretically investigate gap plasmons for two silver nanocubes coupled through a molecular tunnel junction. In absence of tunneling, the red-shift of the bonding mode saturates with decreasing gap distance. Tunneling at small gap distances leads to a damping and slight blue-shift of the bonding mode, but no low-energy charge transfer plasmon mode appears in the spectra. This finding is in stark contrast to recent work of Tan et al. [Science 343, 1496 (2014)].

  2. Further Critique of the Silver Film Superlens

    CERN Document Server

    Christou, George

    2013-01-01

    An explanation is offered of why the surface plasmon waves and their vertically bound enhanced evanescent fields have a much shorter wavelength than the wavelength of the illumination light. This is essential for the clarification of what is claimed to be subwavelength imaging of the silver film superlens. Some of the physical limitations of this lens are considered and it is suggested that no useful imaging results are achievable.

  3. Silver doped metal layers for medical applications

    Czech Academy of Sciences Publication Activity Database

    Kocourek, Tomáš; Jelínek, Miroslav; Mikšovský, Jan; Jurek, Karel; Weiserová, Marie

    Vol. 497. Bristol: IOP Publishing Ltd, 2014, "012021-1"-"012021-9". (497). ISSN 1742-6588. [International Laser Physics Workshop /22./ (LPHYS'13). Praha (CZ), 15.07.2013-19.07.2013] R&D Projects: GA MPO(CZ) FR-TI3/088 Institutional support: RVO:68378271 ; RVO:61388971 Keywords : pulsed laser deposition * thin layers * silver-doped layers * medical application Subject RIV: BM - Solid Matter Physics ; Magnetism

  4. Removal of silver nanoparticles by coagulation processes

    International Nuclear Information System (INIS)

    Highlights: • This study investigated the removal of AgNP suspensions by four regular coagulants. • The optimal removal efficiencies for the four coagulants were achieved at pH 7.5. • The removal efficiency of AgNPs was affected by the natural water characteristics. • TEM and XRD showed that AgNPs or silver-containing NPs were adsorbed onto the flocs. -- Abstract: Commercial use of silver nanoparticles (AgNPs) will lead to a potential route for human exposure via potable water. Coagulation followed by sedimentation, as a conventional technique in the drinking water treatment facilities, may become an important barrier to prevent human from AgNP exposures. This study investigated the removal of AgNP suspensions by four regular coagulants. In the aluminum sulfate and ferric chloride coagulation systems, the water parameters slightly affected the AgNP removal. However, in the poly aluminum chloride and polyferric sulfate coagulation systems, the optimal removal efficiencies were achieved at pH 7.5, while higher or lower of pH could reduce the AgNP removal. Besides, the increasing natural organic matter (NOM) would reduce the AgNP removal, while Ca2+ and suspended solids concentrations would also affect the AgNP removal. In addition, results from the transmission electron microscopy and X-ray diffraction showed AgNPs or silver-containing nanoparticles were adsorbed onto the flocs. Finally, natural water samples were used to validate AgNP removal by coagulation. This study suggests that in the case of release of AgNPs into the source water, the traditional water treatment process, coagulation/sedimentation, can remove AgNPs and minimize the silver ion concentration under the well-optimized conditions

  5. Preparation of nanostructured ultrathin silver layer

    Czech Academy of Sciences Publication Activity Database

    Bulíř, Jiří; Novotný, Michal; Lynnyková, Anna; Lančok, Ján

    2011-01-01

    Roč. 5, č. 5 (2011), "051511-1"-"051511-10". ISSN 1934-2608 R&D Projects: GA AV ČR IAA100100718; GA AV ČR KAN400100653; GA ČR GP202/09/P324 Institutional research plan: CEZ:AV0Z10100522 Keywords : ultrathin silver layers * growth monitoring * optical properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.570, year: 2011

  6. Interaction of Silver Nanopowder with Copper Substrate

    OpenAIRE

    Sopoušek J.; Buršík J.; Zálešák J.; Buršíková V.; Brož P.

    2011-01-01

    Addition of lead into tin based solders represents a serious health risk and environmental problem. Lead-free solders represent one of the ways to remove pollution of lead into environment, nevertheless, new advanced joining methods have to be considered. Aggregation effect of nanoparticles studied in this work seems to be an interesting alternative. It was found experimentally that Ag nanopowder annealed at temperatures above silver oxide decomposition forms continuous Ag layer and yie...

  7. Mycosynthesis of silver nanoparticles bearing antibacterial activity

    OpenAIRE

    Azmath, Pasha; Baker, Syed; Rakshith, Devaraju; Satish, Sreedharamurthy

    2015-01-01

    Mycosynthesis of silver nanoparticles was achieved by endophytic Colletotrichum sp. ALF2-6 inhabiting Andrographis paniculata. Well dispersed nanoparticles were characterized using UV–Visible spectrometry with maximum absorption conferring at 420 nm. FTIR analysis revealed possible biomolecules reducing the metal salt and stabilization of nanoparticles. XRD analysis depicted the diffraction intensities exhibiting between 20 and 80 °C at 2theta angle thus conferring the crystalline nature of n...

  8. Silver Consumers and their Shopping Specifics

    OpenAIRE

    Dagmar Lesakova

    2013-01-01

    Seniors constitute large and constantly growing group of consumers. These „silver consumers“ form a potentially significant market segment for the near future. An ageing population has implications for pension policy, healthcare policy, but also market policy. In spite of the scope of senior´s group, little attention was paid to this segment from the retail industry in Slovakia, and more research to identify their shopping behaviour is required in order to suggest relevant actions. Considerin...

  9. Silver nanoparticles cause complications in pregnant mice

    OpenAIRE

    Zhang XF; Park JH; Choi YJ; Kang MH; Gurunathan S; Kim JH

    2015-01-01

    Xi-Feng Zhang,1,2 Jung-Hyun Park,1 Yun-Jung Choi,1 Min-Hee Kang,1 Sangiliyandi Gurunathan,1 Jin-Hoi Kim11Department of Animal Biotechnology, Konkuk University, Seoul, Republic of Korea; 2College of Biological and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, People’s Republic of ChinaBackground: Silver nanoparticles (AgNPs) have attracted much interest and have been used for antibacterial, antifungal, anticancer, and antiangiogenic applications because of their unique...

  10. The silver of the south Iberian El Argar culture: A first look at production and distribution

    OpenAIRE

    Bartelheim, Martin; Contreras Cortés, Francisco; Moreno Onorato, Auxilio; Murillo-Barroso, Mercedes; Pernicka, Ernst

    2012-01-01

    More than 700 silver objects are known from the Middle Bronze Age El Argar culture, which contrasts significantly with the rest of Bronze Age Europe, where silver is mostly rare. This has traditionally been explained by the difficulties of extracting silver from complex ores by cupellation and the relative abundance of easily accessible occurrences of native silver and silver chlorides in the south of the Iberian peninsula. However, until now in the Iberian Bronze Age the use of native silver...

  11. Biosynthesis of Silver Nanoparticles from Desmodium triflorum: A Novel Approach Towards Weed Utilization

    OpenAIRE

    Naheed Ahmad; Seema Sharma; V. N. Singh; Shamsi, S. F.; Anjum Fatma; Mehta, B. R.

    2011-01-01

    A single-step environmental friendly approach is employed to synthesize silver nanoparticles. The biomolecules found in plants induce the reduction of Ag+ ions from silver nitrate to silver nanoparticles (AgNPs). UV-visible spectrum of the aqueous medium containing silver ions demonstrated a peak at 425 nm corresponding to the plasmon absorbance of silver nanoparticles. Transmission electron microscopy (TEM) showed the formation of well-dispersed silver nanoparticles in the range of 5–20 nm. ...

  12. Silver nanoparticles produced by green production method

    Science.gov (United States)

    Bunghez, Ioana-Raluca; Ion, Rodica-Mariana; Velea, Sanda; Ilie, Lucia; Fierascu, Radu-Claudiu; Dumitriu, Irina; Dinu, Angela; Troncea, Simona

    2010-11-01

    Nanomaterials as novel materials with nanometer sizes are involved in higher performance technology. On this context nanobiotechnology is able to create different nanostructures using living organisms.An attractive research area is the application of microorganisms to synthesize nanoparticles from different metals, one of which is silver, an antimicrobial agent. Green production methods have a considerable interest for environmental protection, often based on plant extracts, organic compounds or microorganisms (bacteria, fungi, algae). Marine plants were used as "real factors" for synthesis of nanoparticles of Au and Ag using different processes of biomineralization. This paper deals with a complete study about obtaining silver nanoparticles from AgNO3 using red algae (Porphyridium purpureum). The red algae contain the red pigment-phycobilins, responsible for red color and for the strong absorption in visible spectrum. The properties and structure of silver nanoparticles have been put into evidence by means of: Fourier transform infrared spectroscopy-FTIR, optical microscopy, X-ray fluorescence spectrometry-EDXRF.

  13. Silver nanoparticles with tunable work functions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Pangpang, E-mail: pangpang@molecular-device.kyushu-u.ac.jp [Education Center for Global Leaders in Molecular Systems for Devices, Kyushu University, Fukuoka 819-0395 (Japan); Tanaka, Daisuke [Department of Electrical and Electronic Engineering, National Institute of Technology, Oita College, Oita 870-0152 (Japan); Ryuzaki, Sou; Araki, Shohei; Okamoto, Koichi; Tamada, Kaoru [Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 819-0395 (Japan)

    2015-10-12

    To improve the efficiencies of electronic devices, materials with variable work functions are required to decrease the energy level differences at the interfaces between working layers. Here, we report a method to obtain silver nanoparticles with tunable work functions, which have the same silver core of 5 nm in diameter and are capped by myristates and 1-octanethoilates self-assembled monolayers, respectively. The silver nanoparticles capped by organic molecules can form a uniform two-dimensional sheet at air-water interface, and the sheet can be transferred on various hydrophobic substrates. The surface potential of the two-dimensional nanoparticle sheet was measured in terms of Kelvin probe force microscopy, and the work function of the sheet was then calculated from the surface potential value by comparing with a reference material. The exchange of the capping molecules results in a work function change of approximately 150–250 meV without affecting their hydrophobicity. We systematically discussed the origin of the work function difference and found it should come mainly from the anchor groups of the ligand molecules. The organic molecule capped nanoparticles with tunable work functions have a potential for the applications in organic electronic devices.

  14. Recovery of silver residues from dental amalgam

    Directory of Open Access Journals (Sweden)

    Heloísa Aparecida Barbosa da Silva Pereira

    2010-04-01

    Full Text Available Dental amalgam residues are probably the most important chemical residues generated from clinical dental practice because of the presence of heavy metals among its constituents, mainly mercury and silver. OBJECTIVE: The purpose of this study was to develop an alternative method for the recovery of silver residues from dental amalgam. MATERIAL AND METHODS: The residue generated after vacuum distillation of dental amalgam for the separation of mercury was initially diluted with 32.5% HNO3, followed by precipitation with 20% NaCl. Sequentially, under constant heating and agitation with NaOH and sucrose, the sample was reduced to metallic silver. However, the processing time was too long, which turned this procedure not viable. In another sequence of experiments, the dilution was accomplished with concentrated HNO3 at 90ºC, followed by precipitation with 20% NaCl. After washing, the pellet was diluted with concentrated NH4OH, water and more NaCl in order to facilitate the reaction with the reducer. RESULTS: Ascorbic acid was efficiently used as reducer, allowing a fast reduction, thus making the procedure viable. CONCLUSIONS: The proposed methodology is of easy application and does not require sophisticated equipment or expensive reagents.

  15. Silver nanoparticles with tunable work functions

    International Nuclear Information System (INIS)

    To improve the efficiencies of electronic devices, materials with variable work functions are required to decrease the energy level differences at the interfaces between working layers. Here, we report a method to obtain silver nanoparticles with tunable work functions, which have the same silver core of 5 nm in diameter and are capped by myristates and 1-octanethoilates self-assembled monolayers, respectively. The silver nanoparticles capped by organic molecules can form a uniform two-dimensional sheet at air-water interface, and the sheet can be transferred on various hydrophobic substrates. The surface potential of the two-dimensional nanoparticle sheet was measured in terms of Kelvin probe force microscopy, and the work function of the sheet was then calculated from the surface potential value by comparing with a reference material. The exchange of the capping molecules results in a work function change of approximately 150–250 meV without affecting their hydrophobicity. We systematically discussed the origin of the work function difference and found it should come mainly from the anchor groups of the ligand molecules. The organic molecule capped nanoparticles with tunable work functions have a potential for the applications in organic electronic devices

  16. Silver enhancement of nanogold and undecagold

    Energy Technology Data Exchange (ETDEWEB)

    Hainfield, J.F.; Furuya, F.R.

    1995-07-01

    A recent advance in immunogold technology has been the use of molecular gold instead of colloidal gold. A number of advantages are realized by this approach, such as stable covalent, site-specific attachment, small probe size and absence of aggregates for improved penetration. Silver enhancement has led to improved and unique results for electron and light microscopy, as well as their use with blots and gels. Most previous work with immunogold silver staining has been done with colloidal gold particles. More recently, large gold compounds (``clusters``) having a definite number of gold atoms and defined organic shell, have been used, frequently with improved results. These gold dusters, large compared to simple compounds, are, however, at the small end of the colloidal gold scale in size; undecagold is 0.8 nm and Nanogold is 1.4 nm. They may be used in practically all applications where colloidal gold is used (Light and electron microscopy, dot blots, etc.) and in some unique applications, where at least the larger colloidal golds don`t work, such as running gold labeled proteins on gels (which are later detected by silver enhancement). The main differences between gold clusters and colloidal golds are the small size of the dusters and their covalent attachment to antibodies or other molecules.

  17. Preparation of Silver Nanostructures from Bicontinuous Microemulsions

    Directory of Open Access Journals (Sweden)

    M. A. Pedroza-Toscano

    2012-01-01

    Full Text Available Precipitation of silver nanoparticles at 70°C was carried out by dosing a 1.3 M sodium borohydride aqueous solution over bicontinuous microemulsions formed with a mixture of sodium bis(2-ethylhexyl sulfosuccinate (AOT and sodium dodecylsulfate (SDS as surfactants, a 0.5 M silver nitrate aqueous solution, and toluene. Weight ratios of 2.5/1 and 3/1 AOT/SDS were used in the precipitation reactions. Silver nanoparticles were characterized by transmission electronic microscopy, X-ray diffraction, and atomic absorption spectroscopy. A mixture of isolated spheroidal nanoparticles (≈15 wt.% with an average diameter around 10 nm and wormlike structures (≈85 wt.% with an average length close to 480 nm and an average diameter ca. 40 nm was obtained, regardless of the AOT/SDS ratio. Higher yields were obtained compared with those reported when reverse microemulsions were employed. Formation of wormlike structures was ascribed to one-dimensional aggregation of crystal and particles within the channels of bicontinuous microemulsions, which performed as templates.

  18. Autometallography: tissue metals demonstrated by a silver enhancement kit

    DEFF Research Database (Denmark)

    Danscher, G; Nørgaard, J O; Baatrup, E

    1987-01-01

    In biological tissue, minute accumulations of gold, silver, mercury and zinc can be visualized by a technique whereby metallic silver is precipitated on tiny accumulations of the two noble metals, or on selenites or sulphides of all four metals. In the present study a silver enhancement kit, prim...... methods and for demonstration of gold, silver, and mercury in tissues from animals intravitally exposed to these metals. It can also be used for counterstaining silver treated osmium fixed tissues embedded in plastic. Udgivelsesdato: 1987-null......In biological tissue, minute accumulations of gold, silver, mercury and zinc can be visualized by a technique whereby metallic silver is precipitated on tiny accumulations of the two noble metals, or on selenites or sulphides of all four metals. In the present study a silver enhancement kit......, primarily intended for the amplification of colloidal gold particles, has been used to demonstrate these catalytic tissue metals. Sections from animals exposed intravitally to aurothiomalatate, silver lactate, mercury chloride, sodium selenite or perfused with sodium sulphide were subjected to a commercial...

  19. Manufacturing of nano silver solution using electrochemical technology

    International Nuclear Information System (INIS)

    Nano Silver solution used for killing many types of bacteria has been studied, manufactured and applied extensively. Common chemical, physical methods and mechanism for manufacturing nano silver solution can only produce low degree of purity and limit abilities to kill bacteria and apply in medical and pharmaceutical industries. Electrochemical technology uses the Ag anode dissolving process to produce high purity nano silver solution without using complex equipments. In comparison with other physical and chemical methods, electrochemical technology can produce nano silver solution with the same structure and concentration, but difference in electrochemical properties such as electrical conductivity and the Zeta potential. (author)

  20. Synthesis of silver nanoparticles using medicinal Zizyphus xylopyrus bark extract

    Science.gov (United States)

    Sumi Maria, Babu; Devadiga, Aishwarya; Shetty Kodialbail, Vidya; Saidutta, M. B.

    2015-08-01

    In the present paper, biosynthesis of silver nanoparticles using Zizyphus xylopyrus bark extract is reported. Z. xylopyrus bark extract is efficiently used for the biosynthesis of silver nanoparticles. UV-Visible spectroscopy showed surface plasmon resonance peaks in the range 413-420 nm confirming the formation of silver nanoparticles. Different factors affecting the synthesis of silver nanoparticles like methodology for the preparation of extract, concentration of silver nitrate solution used for biosynthesis and initial pH of the reaction mixture were studied. The extract prepared with 10 mM AgNO3 solution by reflux extraction method at optimum initial pH of 11, resulted in higher conversion of silver ions to silver nanoparticles as compared with those prepared by open heating or ultrasonication. SEM analysis showed that the biosynthesized nanoparticles are spherical in nature and ranged from 60 to 70 nm in size. EDX suggested that the silver nanoparticles must be capped by the organic components present in the plant extract. This simple process for the biosynthesis of silver nanoparticles using aqueous extract of Z. xylopyrus is a green technology without the usage of hazardous and toxic solvents and chemicals and hence is environment friendly. The process has several advantages with reference to cost, compatibility for its application in medical and drug delivery, as well as for large-scale commercial production.

  1. Smoothing of ultrathin silver films by transition metal seeding

    Science.gov (United States)

    Anders, André; Byon, Eungsun; Kim, Dong-Ho; Fukuda, Kentaro; Lim, Sunnie H. N.

    2006-11-01

    The nucleation and coalescence of silver islands on coated glass was investigated by in situ measurements of the sheet resistance. Sub-monolayer amounts of niobium and other transition metals were deposited prior to the deposition of silver. It was found that in some cases, the transition metals lead to coalescence of silver at nominally thinner films with smoother topology. The smoothing or roughening effects by the presence of the transition metal can be explained by kinetically limited transition metal islands growth and oxidation, followed by defect-dominated nucleation of silver.

  2. Carnosine induced formation of silver nanochains: A radiolytic study

    Science.gov (United States)

    Malkar, Vishwabharati V.; Mukherjee, Tulsi; Kapoor, Sudhir

    2015-02-01

    Interaction of carnosine with silver clusters and its nanoparticles is studied at pH 8.2 and 9.2. Using time resolved kinetic measurements we show that carnosine interacts with the charged silver clusters. Using ionizing radiation silver particles are also produced in aqueous solution. In the presence of carnosine distinct differences in the surface plasmon absorption band of Ag nanoparticles is observed with change in pH. The results suggest that silver nanochains get formed through dipole-dipole interaction due to weak interaction with carnosine. UV-Vis spectrophotometry and transmission electron microscopy are used to characterize the nanoparticles.

  3. Formation of silver microbelt structures by laser irradiation of silver nanoparticles in ethanol

    Directory of Open Access Journals (Sweden)

    Zamiri R

    2011-10-01

    Full Text Available Reza Zamiri1, Azmi Zakaria1,2, Mohd Shahril Husin1, Zaidan Abd Wahab1, Forough Kalaei Nazarpour3 1Department of Physics, Faculty of Science, 2Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, 3Institute of Bioscience, Universiti Putra Malaysia, Serdang, Selangor, Malaysia Abstract: In the present work, we prepared silver nanoparticles by laser ablation of pure silver plate in ethanol and then irradiated the silver nanoparticles using a 532 nm Q-switched Nd:YAG pulsed laser. Transmission electron microscopic images of the sample after irradiation clearly showed formation of big structures, such as microrods and microbelts in ethanol. The obtained microbelts had a width of about 0.166 µm and a length of 1.472 µm. The reason for the formation of such a big structure is the tendency of the nanoparticles to aggregate in ethanol before irradiation, which causes fusion of the nanoparticles. Keywords: nanomaterial, laser ablation, nanoparticles

  4. Sponge-like silver obtained by decomposition of silver nitrate hexamethylenetetramine complex

    Science.gov (United States)

    Afanasiev, Pavel

    2016-07-01

    Silver nitrate hexamethylenetetramine [Ag(NO3)·N4(CH2)6] coordination compound has been prepared via aqueous route and characterized by chemical analysis, XRD and electron microscopy. Decomposition of [Ag(NO3)·N4(CH2)6] under hydrogen and under inert has been studied by thermal analysis and mass spectrometry. Thermal decomposition of [Ag(NO3)·N4(CH2)6] proceeds in the range 200-250 °C as a self-propagating rapid redox process accompanied with the release of multiple gases. The decomposition leads to formation of sponge-like silver having hierarchical open pore system with pore size spanning from 10 μm to 10 nm. The as-obtained silver sponges exhibited favorable activity toward H2O2 electrochemical reduction, making them potentially interesting as non-enzyme hydrogen peroxide sensors.

  5. My Quarter Century with Jan

    CERN Document Server

    Lewin, W H G

    2001-01-01

    A quarter century ago, Jan van Paradijs and I started on a scientific journey, our lives became entwined, and a friendship evolved that shaped both our lives scientifically and in personal matters. To tell our story was very difficult for me. I went through 24 years of notes in my calendars and re-lived more than 8000 days of my own and Jan's life, 20 years of slides, 15 years of e-mail. There were times that I had to stop and leave it alone for a week or more as it became too emotional. Few people know (perhaps only two) what we meant for each other. When Jan died, part of me died.

  6. Countering 21st Century Threats

    DEFF Research Database (Denmark)

    Scharling Pedersen, Peter; Pillai, Chad M.; Hun, Lee Jae

    2015-01-01

    The United States and its Allies confront an increasingly volatile world where threats range from traditional state-on-state challenges to non-state transnational networks. To successfully combat these 21st Century problems, in an era of resource and geo-political power constraints, the U.S. and......), Counter-Terrorism (CT), and Security and Stability Operations (SSO). • Establishing a construct that allows a strategic Whole-of-Government capacity for operations coordinated by joint interagency task forces. • Continue to developing the Global SOF network. • Increased intelligence sharing in areas of...... shared interests pre-crisis. • Establish political agreements and/or intentions with partners to address potential threats. • Establishing mutual trust through Building Partnership Capacity with capable SOF and intelligence organizations....

  7. Separation of silver ions and starch modified silver nanoparticles using high performance liquid chromatography with ultraviolet and inductively coupled mass spectrometric detection

    Science.gov (United States)

    Hanley, Traci A.; Saadawi, Ryan; Zhang, Peng; Caruso, Joseph A.; Landero-Figueroa, Julio

    2014-10-01

    The production of commercially available products marketed to contain silver nanoparticles is rapidly increasing. Species-specific toxicity is a phenomenon associated with many elements, including silver, making it imperative to develop a method to identify and quantify the various forms of silver (namely, silver ions vs. silver nanoparticles) possibly present in these products. In this study a method was developed using high performance liquid chromatography (HPLC) with ultraviolet (UV-VIS) and inductively coupled mass spectrometric (ICP-MS) detection to separate starch stabilized silver nanoparticles (AgNPs) and silver ions (Ag+) by cation exchange chromatography with 0.5 M nitric acid mobile phase. The silver nanoparticles and ions were baseline resolved with an ICP-MS response linear over four orders of magnitude, 0.04 mg kg- 1 detection limit, and 90% chromatographic recovery for silver solutions containing ions and starch stabilized silver nanoparticles smaller than 100 nm.

  8. Separation of silver ions and starch modified silver nanoparticles using high performance liquid chromatography with ultraviolet and inductively coupled mass spectrometric detection

    International Nuclear Information System (INIS)

    The production of commercially available products marketed to contain silver nanoparticles is rapidly increasing. Species-specific toxicity is a phenomenon associated with many elements, including silver, making it imperative to develop a method to identify and quantify the various forms of silver (namely, silver ions vs. silver nanoparticles) possibly present in these products. In this study a method was developed using high performance liquid chromatography (HPLC) with ultraviolet (UV–VIS) and inductively coupled mass spectrometric (ICP-MS) detection to separate starch stabilized silver nanoparticles (AgNPs) and silver ions (Ag+) by cation exchange chromatography with 0.5 M nitric acid mobile phase. The silver nanoparticles and ions were baseline resolved with an ICP-MS response linear over four orders of magnitude, 0.04 mg kg−1 detection limit, and 90% chromatographic recovery for silver solutions containing ions and starch stabilized silver nanoparticles smaller than 100 nm

  9. A brief history of the American radium industry and its ties to the scientific community of its early Twentieth Century

    International Nuclear Information System (INIS)

    Federally funded remedial action projects are presently underway in New Jersey and Colorado at sites containing 226Ra and other radionuclides from radium-uranium ore extraction plants that operated during the early twentieth century. They are but the latest chapter in the story of an American industry that emerged and perished in the span of three decades. Major extraction plants were established in or near Denver (CO), Pittsburgh (PA), and New York City (NY) to process radium from ore that came largely from the carnotite deposits of western Colorado and eastern Utah. The staffs of these plants included some of the finest chemists and physicists in the nation, and the highly-refined radium products found a variety of uses in medicine and industry. The discovery of high-grade pitchblende ores in the Belgian Congo and the subsequent opening of an extraction plant near Antwerp, Belgium, in 1992, however, created an economic climate that put an end to the American radium industry. The geologic, chemical, and engineering information gathered during this era formed the basis of the uranium industry of the later part of the century, while the tailings and residues came to be viewed as environmental problems during the same period

  10. Spatially controlled synthesis of silver nanoparticles and nanowires by photosensitized reduction

    Energy Technology Data Exchange (ETDEWEB)

    Jradi, S; Zeng, X H; Plain, J; Royer, P; Bachelot, R; Akil, S [Laboratoire de Nanotechnologie et d' Instrumentation Optique, ICD CNRS FRE 2848, Universite de Technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes (France); Balan, L; Lougnot, D J; Soppera, O; Vidal, L, E-mail: lavinia.balan@uha.fr [Institut de Science des Materiaux de Mulhouse CNRS LRC 7228, 15 rue Jean Starcky, 68057 Mulhouse (France)

    2010-03-05

    The present paper reports on the spatially controlled synthesis of silver nanoparticles (NPs) and silver nanowires by photosensitized reduction. In a first approach, direct photogeneration of silver NPs at the end of an optical fiber was carried out. Control of both size and density of silver NPs was possible by changing the photonic conditions. In a further development, a photochemically assisted procedure allowing silver to be deposited at the surface of a polymer microtip was implemented. Finally, polymer tips terminated by silver nanowires were fabricated by simultaneous photopolymerization and silver photoreduction. The silver NPs were characterized by UV-visible spectroscopy and scanning electron microscopy.

  11. Fine structures in the optical absorption spectra of photochemical silver in silver halides? A call for further research

    OpenAIRE

    Georgiev, Mladen

    2007-01-01

    A survey is presented of the work done so far to check earlier claims that a fine structure may be observed to occur under certain circumstances in the impurity spectral range of the optical absorption spectra of silver halides following photostimulation in the intrinsic range. This structure, associated with the photochemical formation of silver specks, has been questioned over the years. We now weigh carefully the experimental evidence on the silver halides against a background of similar d...

  12. Alkyne-Azide Cycloaddition Catalyzed by Silver Chloride and “Abnormal” Silver N-Heterocyclic Carbene Complex

    Directory of Open Access Journals (Sweden)

    Aldo I. Ortega-Arizmendi

    2013-01-01

    Full Text Available A library of 1,2,3-triazoles was synthesized from diverse alkynes and azides using catalytic amounts of silver chloride instead of copper compounds. In addition, a novel “abnormal” silver N-heterocyclic carbene complex was tested as catalyst in this process. The results suggest that the reaction requires only 0.5% of silver complex, affording 1,2,3-triazoles in good yields.

  13. Concentration Effects of Silver Ions on Ionic Conductivities of Molten Silver Halides

    OpenAIRE

    Okada T.; Kawakita Y.; Tahara S.; Ohno S.; Takeda S

    2011-01-01

    Ionic conductivities of molten (RbX)c(AgX)1-c (X = Cl and I) mixtures were measured to clarify the concentration effects of silver ions on ionic conductivities of molten silver halides. It is found that the addition of RbX to molten AgX rapidly reduces the ionic conductivity with 0 ≤ c ≤ 0.4. It suggests that strong Ag-Ag correlation is necessary to fast conduction of Ag ions in molten state. The absolute values of ionic conductivity for (RbCl)c(AgCl)1-c are larger than those for (R...

  14. Shape transformation of silver nanospheres to silver nanoplates induced by redox reaction of hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Parnklang, Tewarak; Lamlua, Banjongsak; Gatemala, Harnchana; Thammacharoen, Chuchaat [Department of Chemistry, Faculty of Science, Chulalongkorn University, 254 Phyathai Road, Patumwan, Bangkok 10330 (Thailand); Kuimalee, Surasak [Industrial Chemistry and Textile Technology Programme, Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Lohwongwatana, Boonrat [Metallurgical Engineering Department, Faculty of Engineering, Chulalongkorn University, 254 Phyathai Road, Patumwan, Bangkok 10330 (Thailand); Ekgasit, Sanong, E-mail: sanong.e@chula.ac.th [Department of Chemistry, Faculty of Science, Chulalongkorn University, 254 Phyathai Road, Patumwan, Bangkok 10330 (Thailand)

    2015-03-01

    In this paper we demonstrate a simple and rapid shape transformation of silver nanospheres (AgNSs) to silver nanoplates (AgNPls) using the oxidation and reduction capabilities of hydrogen peroxide. AgNPls having tunable surface plasmon resonance across the visible region with average size of 40–100 nm and thickness of 10–15 nm can be fabricated within 2 min simply by adding H{sub 2}O{sub 2} into a colloid of AgNSs with average particle size of 7 nm. The efficiency of H{sub 2}O{sub 2} as a shape-transforming agent depends strongly on its concentration, pH of the AgNS colloid, and the employed stabilizers. H{sub 2}O{sub 2} oxidizes AgNSs to silver ions while concertedly reduces silver ions to silver atom necessary for the growth of AgNPls. The shape transformation reaction was conducted at a relatively low concentration of H{sub 2}O{sub 2} in order to minimize the oxidative dissolution while facilitating kinetically controlled growth of AgNPls under a near neutral pH. Polyvinyl-pyrrolidone is an effective steric stabilizer preventing aggregation while assisting the growth of AgNPls. Trisodium citrate inhibits the formation of AgNPls under the H{sub 2}O{sub 2} reduction as it forms a stable complex with silver ions capable of withstanding the weakly reducing power of H{sub 2}O{sub 2}. After a complete consumption of AgNSs, large nanoplates grows with an expense of smaller nanoplates. The growth continues until H{sub 2}O{sub 2} is exhausted. A high concentration H{sub 2}O{sub 2} promotes catalytic decomposition of H{sub 2}O{sub 2} on the surface of AgNSs and oxidative dissolution of AgNSs without a formation of AgNPls. - Graphical abstract: Proposed mechanism for the shape transformation of AgNSs to AgNPls induced by the oxidation/reduction of H{sub 2}O{sub 2}. - Highlights: • Rapid shape transformation of silver nanospheres to nanoplates by H{sub 2}O{sub 2}. • Structural change completes in 2 min with a yellow-to-blue color change. • Selective fabrication of

  15. Total level and release of silver from a nanoparticles containing dressing used in burns care – a pilot study

    Directory of Open Access Journals (Sweden)

    Rigo C.

    2013-04-01

    Full Text Available For centuries silver and its compounds have been in use to control infection and avoid septicaemia in the care of burns and chronic wounds. Renewed interest has resulted in a number of silver-based dressings exploiting nanotechnology that are now widely employed in burns centers. Despite extensive use, a systematic study of the chemical composition, release kinetics and biochemical action of these products has yet to be published. In this work we have characterized the morphology and elemental composition of a commercial dressings containing Ag by SEM-EDS. The silver content was determined by ICP-MS to be about 1.4 mg cm-2. Release kinetics in ultra pure water, physiological saline solution and human serum substitute were then deeply investigated. The highest release rates were found in serum substitute, with a maximum of 2.6 μg hr-1 cm-2. Our results show that the mean inhibitory concentrations are exceeded for most common pathogens in serum substitute and sterile water, while the presence of high Cllevels inactivates the dressings.

  16. Mercury (not always rising and the social economy of nineteenth-century Peru

    Directory of Open Access Journals (Sweden)

    José R. Deustua

    2010-12-01

    Full Text Available This study focuses on the Peruvian mining industry of mercury or azogue in the nineteenth century.Mercury was a crucial component for Andean and Mexican silver mining during colonialtimes and still in the first century of Republican Peru. However, it was not the booming industrythat occurred at the end of the sixteenth century, in the second half of the seventeenth, and at thesecond half of the eighteenth century with production peaks at 13 000, 8000 and 7000 quintalsper year. During the nineteenth century it was rather a relative modest industry («not always rising» but also had moments of peak and decline. The article discusses production figures from the1950 by engineers Fernandez Concha, Yates, and Kent, with new statistics coming from archivalsources, which shows important regional levels of production and articulation with silver miningcenters such as Cerro de Pasco. The article also shows that mercury production was not limitedto the old colonial Huancavelica mine of Santa Bárbara but to other areas in the Huancavelicaregion, such as Angaraes and Lircay, or beyond Hunacavelica, such as Chonta in Cerro de Pascoor even Chachapoyas. It also focuses on the conflictive dynamics that mining production meantfor criollo business people, the government, merchants, and indigenous workers. There wereseveral business efforts to revitalize the mine of Santa Bárbara as well as to invest in Huancavelicamercury mining in combination with government initiatives and actions, but it is also clear theaction of mercury merchants, rescatires, who many times rather dealt with workers and humachis,independent laborers or small entrepreneurs, many times Andean Quechua peasants, who ratherbenefitted during the down cycles in mercury production. Finally, after analyzing this particularindustry, the author reflects on the meaning of economic development and historical studies tocriticize U.S. economic historians such as Stephen Haber (from Stanford University

  17. Environmental legacy of copper metallurgy and Mongol silver smelting recorded in Yunnan Lake sediments.

    Science.gov (United States)

    Hillman, Aubrey L; Abbott, Mark B; Yu, JunQing; Bain, Daniel J; Chiou-Peng, TzeHuey

    2015-03-17

    Geochemical measurements on well-dated sediment cores from Lake Er (Erhai) are used to determine the timing of changes in metal concentrations over 4500 years in Yunnan, a borderland region in southwestern China noted for rich mineral deposits but with inadequately documented metallurgical history. Our findings add new insight into the impacts and environmental legacy of human exploitation of metal resources in Yunnan history. We observe an increase in copper at 1500 BC resulting from atmospheric emissions associated with metallurgy. These data clarify the chronological issues related to links between the onset of Yunnan metallurgy and the advent of bronze technology in adjacent Southeast Asia, subjects that have been debated for nearly half a century. We also observe an increase from 1100 to 1300 AD in a number of heavy metals including lead, silver, zinc, and cadmium from atmospheric emissions associated with silver smelting. Culminating during the rule of the Mongols, known as the Yuan Dynasty (1271-1368 AD), these metal concentrations approach levels three to four times higher than those from industrialized mining activity occurring within the catchment today. Notably, the concentrations of lead approach levels at which harmful effects may be observed in aquatic organisms. The persistence of this lead pollution over time created an environmental legacy that likely contributes to known issues in modern day sediment quality. We demonstrate that historic metallurgical production in Yunnan can cause substantial impacts on the sediment quality of lake systems, similar to other paleolimnological findings around the globe. PMID:25685905

  18. In-situ XRF and LIBS analysis of roman silver denarii

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, A. El; Harith, M.A. [National Institute for Laser- Enhanced Science (NILES), Cairo University, Giza (Egypt); Ferretti, M. [Istituto per le Tecnologie Applicate ai Beni Culturali, Area della Ricerca del CNR di Montelibretti, Roma (Italy); Foresta, A.; Legnaioli, S.; Lorenzetti, G.; Palleschi, V.; Pardini, L., E-mail: incenzo.palleschi@cnr.it [Istituto di Chimica dei Composti Organometallici del CNR. Area della Ricerca del CNR di Pisa (Italy); Nebbia, E. [Universita degli Studi di Torino (Italy); Catalli, F. [Monetiere di Firenze, Museo Archeologico Nazionale, Firenze (Italy)

    2011-07-01

    Full text: In this paper we present the result of a study performed on a large collection of silver roman republican denarii, encompassing about two centuries of history. The joint use of Laser-Induced Breakdown Spectroscopy (LIBS) and X-Ray Fluorescence (XRF) spectroscopy allowed for an accurate determination of the coins' elemental composition; the measurements, performed mostly in situ at the 'Monetiere' in Florence, revealed a striking correlation of the 'quality' of the silver alloy with some crucial contemporary events. This finding was used for classifying a group of denarii whose dating was otherwise impossible. The results reported demonstrate the possibility of analyzing in short time and in situ a statistically significant number of coins. Useful information can be obtained about the coin composition, both for main components and traces that could be used for classifying the coins in groups, according to different levels of concentrations of the detected elements. The comparison with other contemporary denarii allowed also to controvert a recent theory on the origin of the so called 'serrated' denarii (denarii showing notched chisel marks on the edge of the coin). (author)

  19. Mountains, glaciers, and mines—The geological story of the Blue River valley, Colorado, and its surrounding mountains

    Science.gov (United States)

    Kellogg, Karl; Bryant, Bruce; Shroba, Ralph R.

    2016-01-01

    This report describes, in a nontechnical style, the geologic history and mining activity in the Blue River region of Colorado, which includes all of Summit County. The geologic story begins with the formation of ancient basement rocks, as old as about 1700 million years, and continues with the deposition of sedimentary rocks on a vast erosional surface beginning in the Cambrian Period (about 530 million years ago). This deposition was interrupted by uplift of the Ancestral Rocky Mountains during the late Paleozoic Era (about 300 million years ago). The present Rocky Mountains began to rise at the close of the Mesozoic Era (about 65 million years ago). A few tens of millions years ago, rifting began to form the Blue River valley; a major fault along the east side of the Gore Range dropped the east side down, forming the present valley. The valley once was filled by sediments and volcanic rocks that are now largely eroded. During the last few hundred-thousand years, at least two periods of glaciation sculpted the mountains bordering the valley and glaciers extended down the Blue River valley as far south as present Dillon Reservoir. Discovery of deposits of gold, silver, copper, and zinc in the late 1800s, particularly in the Breckenridge region, brought an influx of early settlers. The world-class molybdenum deposit at Climax, mined since the First World War, reopened in 2012 after a period of closure.

  20. Uranium favorability of precambrian rocks in the Badger Flats - Elkhorn Thrust Area, Park and Teller Counties, Colorado

    International Nuclear Information System (INIS)

    The area is approximately 1,800 square miles and extends from Cripple Creek northward to Fairplay and Bailey. The Precambrian rocks include the metamorphic sequences of the Idaho Springs Formation and the Boulder Creek Granodiorite, Silver Plume Granite, Pikes Peak Granite, and Redskin Granite. The known uranium deposits in the area include six vein deposits, three pegmatite occurrences, and one zone of probable secondary enrichment; they have not yielded any significant production. The vein deposits are probably the result of downward percolation of ground water. The zone of secondary uranium enrichment may have formed above a volcanic pipe, vein, or tuffaceous lake bed. Favorability in the area is considered good for both vein and large, disseminated, low-grade uranium deposits. On the bases of known uranium occurrences, favorable structures and host rocks, and a water-sampling program, recommendations are given for exploration. The occurrences in the area have substantial similarities with the Rossing deposit in South-West Africa and the Wheeler Basin uranium occurrence in Grand County, Colorado. 6 figures, 9 tables