WorldWideScience

Sample records for century colorado silver

  1. 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

  2. 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".

  3. State policy and monetary circulation in the Seventeenth Century Crown of Aragon: The depreciation of silver currency

    Directory of Open Access Journals (Sweden)

    José Antonio Mateos Royo

    2011-12-01

    Full Text Available This paper looks at the state policy applied to silver in the Spanish territories of the Crown of Aragon in the seventeenth century, where increasing demand for silver coins with a lower intrinsic than market value opened up debate on the depreciation of the domestic silver coinage. The monarchy was weaker in the Crown of Aragon than in Castile, and it was therefore obliged to negotiate these measures with the elites and institutionsof each kingdom. The paper examines the fiscal and monetary reasons forreforms, as well as the extent of political support achieved in each kingdom.

  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. Nondestructive Analysis of Silver Coins Minted in Taras (South Italy between the V and the III Centuries BC

    Directory of Open Access Journals (Sweden)

    Alessandro Buccolieri

    2014-01-01

    Full Text Available This work enters in an interdisciplinary research project involving the archaeometrical analysis of ancient silver coins minted in the Greek colony of Taras (the modern south Italian town of Taranto between the V century BC and the III century BC. In this work, by comparing the results obtained from X-ray microanalysis data acquired from the least corroded surface areas and the cross-section of coins from SEM-EDX and from XRF analysis, we have demonstrated that analysed coins exhibited a corrosion layer no more than 25 μm and that surface silver enrichment was less than 1 wt%. Thus, the data obtained by using X-ray microanalysis from surface may not significantly differ from the original bulk composition. Our results demonstrate that the silver content in the coins decreases considerably ranging from about 97% for the older down to 80% for the ones of 3rd Evans period (300–270 BC, corresponding to the significant social change in the period.

  9. Mid-21st century projections in temperature extremes in the southern Colorado Rocky Mountains from regional climate models

    Energy Technology Data Exchange (ETDEWEB)

    Rangwala, Imtiaz [NOAA Earth System Research Laboratory, Physical Sciences Division, Boulder, CO (United States); Rutgers University, Department of Marine and Coastal Sciences, New Brunswick, NJ (United States); Barsugli, Joseph [NOAA Earth System Research Laboratory, Physical Sciences Division, Boulder, CO (United States); Cozzetto, Karen; Neff, Jason [University of Colorado, Geological Sciences Department and Environmental Studies Program, Boulder, CO (United States); Prairie, James [University of Colorado, Bureau of Reclamation, Boulder, CO (United States)

    2012-10-15

    This study analyzes mid-21st century projections of daily surface air minimum (T{sub min}) and maximum (T{sub max}) temperatures, by season and elevation, over the southern range of the Colorado Rocky Mountains. The projections are from four regional climate models (RCMs) that are part of the North American Regional Climate Change Assessment Program (NARCCAP). All four RCMs project 2 C or higher increases in T{sub min} and T{sub max} for all seasons. However, there are much greater (>3 C) increases in T{sub max} during summer at higher elevations and in T{sub min} during winter at lower elevations. T{sub max} increases during summer are associated with drying conditions. The models simulate large reductions in latent heat fluxes and increases in sensible heat fluxes that are, in part, caused by decreases in precipitation and soil moisture. T{sub min} increases during winter are found to be associated with decreases in surface snow cover, and increases in soil moisture and atmospheric water vapor. The increased moistening of the soil and atmosphere facilitates a greater diurnal retention of the daytime solar energy in the land surface and amplifies the longwave heating of the land surface at night. We hypothesize that the presence of significant surface moisture fluxes can modify the effects of snow-albedo feedback and results in greater wintertime warming at night than during the day. (orig.)

  10. 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.

  11. 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

  12. 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.

  13. Mineral resource of the month: silver

    Science.gov (United States)

    Brooks, William E.

    2007-01-01

    Silver has been used for thousands of years as ornaments and utensils, for trade and as the basis of many monetary systems. The metal has played an important part in world history. Silver from the mines at Laurion, Greece, for example, financed the Greek victory over the Persians in 480 B.C. Silver from Potosi, Bolivia, helped Spain become a world power in the 16th and 17th centuries. And silver from the gold-silver ores at the Comstock Lode in Virginia City, Nev., helped keep the Union solvent during the Civil War.

  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. Silver Sulfadiazine

    Science.gov (United States)

    ... degree burns. It kills a wide variety of bacteria.This medication is sometimes prescribed for other uses; ... or burned skin. Always wear a sterile, disposable glove when you apply silver sulfadiazine. Cover the cleaned ...

  17. 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...

  18. 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

  19. Mineral resource of the month: silver

    Science.gov (United States)

    Katrivanos, Florence C.

    2015-01-01

    Silver, one of the eight precious or noble metals, has been used extensively throughout recorded history for various medical purposes, ornaments and utensils, and for its intrinsic value as the basis for trade and monetary systems. Silver has played a significant role in world history, financing a Greek victory over the Persians in 480 B.C., helping Spain become a world power in the 16th and 17th centuries, and helping fund the Union forces during the U.S. Civil War, to give a few examples.

  20. 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.

  1. 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)

  2. 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…

  3. The use of silver-based dressings in wound care.

    Science.gov (United States)

    Dowsett, Caroline

    Chronic wounds such as leg ulcers and pressure ulcers are often slow to heal. One of the causes of delayed wound healing is the presence of micro-organisms in the wound. A strategy for the prevention and treatment of wound colonisation or infection, which is receiving renewed attention, is the use of silver-based dressings. Silver has been used as an antimicrobial agent for centuries. It is effective against a broad range of bacteria (including methicillin and vancomycin-resistant strains), yeast, fungi and viruses. A number of new silver-based dressings, some of which act by the sustained release of silver ions to the wound bed, have recently become available, but there are wide variations in the amount of data supporting the use of individual products. This article reviews the evidence base for silver-containing dressings to help practitioners select the most appropriate product for the type of wound being treated. PMID:15551918

  4. Updated streamflow reconstructions for the Upper Colorado River Basin

    Science.gov (United States)

    Woodhouse, C.A.; Gray, S.T.; Meko, D.M.

    2006-01-01

    Updated proxy reconstructions of water year (October-September) streamflow for four key gauges in the Upper Colorado River Basin were generated using an expanded tree ring network and longer calibration records than in previous efforts. Reconstructed gauges include the Green River at Green River, Utah; Colorado near Cisco, Utah; San Juan near Bluff, Utah; and Colorado at Lees Ferry, Arizona. The reconstructions explain 72-81% of the variance in the gauge records, and results are robust across several reconstruction approaches. Time series plots as well as results of cross-spectral analysis indicate strong spatial coherence in runoff variations across the subbasins. The Lees Ferry reconstruction suggests a higher long-term mean than previous reconstructions but strongly supports earlier findings that Colorado River allocations were based on one of the wettest periods in the past 5 centuries and that droughts more severe than any 20th to 21st century event occurred in the past. Copyright 2006 by the American Geophysical Union.

  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. 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...

  8. 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.

  9. 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.

  10. 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.

  11. Mineral commodity profiles: Silver

    Science.gov (United States)

    Butterman, W.C.; Hilliard, Henry E.

    2005-01-01

    Overview -- Silver is one of the eight precious, or noble, metals; the others are gold and the six platinum-group metals (PGM). World mine production in 2001 was 18,700 metric tons (t) and came from mines in 60 countries; the 10 leading producing countries accounted for 86 percent of the total. The largest producer was Mexico, followed by Peru, Australia, and the United States. About 25 percent of the silver mined in the world in 2001 came from silver ores; 15 percent, from gold ores and the remaining 60 percent, from copper, lead, and zinc ores. In the United States, 14 percent of the silver mined in 2001 came from silver ores; 39 percent, from gold ores; 10 percent, from copper and copper-molybdenum ores; and 37 percent, from lead, zinc, and lead-zinc ores. The precious metal ores (gold and silver) came from 30 lode mines and 10 placer mines; the base-metal ores (copper, lead, molybdenum, and zinc) came from 24 lode mines. Placer mines yielded less than 1 percent of the national silver production. Silver was mined in 12 States, of which Nevada was by far the largest producer; it accounted for nearly one-third of the national total. The production of silver at domestic mines generated employment for about 1,100 mine and mill workers. The value of mined domestic silver was estimated to be $290 million. Of the nearly 27,000 t of world silver that was fabricated in 2001, about one-third went into jewelry and silverware, one-fourth into the light-sensitive compounds used in photography, and nearly all the remainder went for industrial uses, of which there were 7 substantial uses and many other small-volume uses. By comparison, 85 percent of the silver used in the United States went to photography and industrial uses, 8 percent to jewelry and silverware, and 7 percent to coins and medals. The United States was the largest consumer of silver followed by India, Japan, and Italy; the 13 largest consuming countries accounted for nearly 90 percent of the world total. In the

  12. 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.

  13. 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...

  14. The Colorado Adoption Project.

    Science.gov (United States)

    Plomin, R; DeFries, J C

    1983-04-01

    This report provides an overview of the Colorado Adoption Project (CAP), a longitudinal, prospective, multivariate adoption study of behavioral development. Examples of the types of analyses that can be conducted using this design are presented. The examples are based on general cognitive-ability data for adoptive, biological, and control parents; assessments of their home environment; and Bayley Mental Development Index scores for 152 adopted children and 120 matched control children tested at both 1 and 2 years of age. The illustrative analyses include matched control children tested at both 1 and 2 years of age. The illustrative analyses include examination of genetic and environmental sources of variance, identification of environmental influence devoid of genetic bias, assessment of genotype-environment interaction and correlation, and analyses of the etiology of change and continuity in development.

  15. Pikes Peak, Colorado

    Science.gov (United States)

    Brunstein, Craig; Quesenberry, Carol; Davis, John; Jackson, Gene; Scott, Glenn R.; D'Erchia, Terry D.; Swibas, Ed; Carter, Lorna; McKinney, Kevin; Cole, Jim

    2006-01-01

    For 200 years, Pikes Peak has been a symbol of America's Western Frontier--a beacon that drew prospectors during the great 1859-60 Gold Rush to the 'Pikes Peak country,' the scenic destination for hundreds of thousands of visitors each year, and an enduring source of pride for cities in the region, the State of Colorado, and the Nation. November 2006 marks the 200th anniversary of the Zebulon M. Pike expedition's first sighting of what has become one of the world's most famous mountains--Pikes Peak. In the decades following that sighting, Pikes Peak became symbolic of America's Western Frontier, embodying the spirit of Native Americans, early explorers, trappers, and traders who traversed the vast uncharted wilderness of the Western Great Plains and the Southern Rocky Mountains. High-quality printed paper copies of this poster are available at no cost from Information Services, U.S. Geological Survey (1-888-ASK-USGS).

  16. 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

  17. 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.

  18. Debris flow occurrence and sediment persistence, Upper Colorado River Valley, CO

    Science.gov (United States)

    Grimsley, Kyle J; Rathburn, Sara L.; Friedman, Jonathan M.; Mangano, Joseph F.

    2016-01-01

    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.

  19. 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.

  20. 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...

  1. 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...

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

    Science.gov (United States)

    : Beard, L. Sue; 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. 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…

  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. 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

  6. Silver Bear for Screenplay

    Institute of Scientific and Technical Information of China (English)

    LIU YUNYUN

    2010-01-01

    @@ Chinese director Wang Quan'an won the Silver Bear Prize at the 60th Berlin International Film Festival that lasted during February 11 to 21 tor the best screenplay for his movie Apart Together.The film also opened the festival.

  7. 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.

  8. 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.

  9. 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.

  10. Introduction: CRevolution 2: origin and evolution of the Colorado River System II

    Science.gov (United States)

    Karlstrom, Karl E.; Beard, L. Sue; House, Kyle; Young, Richard A.; Aslan, Andres; Billingsley, George; Pederson, Joel

    2012-01-01

    A 2010 Colorado River symposium held in Flagstaff, Arizona, in May 2010, had 70 participants who engaged in intense debate about the origin and evolution of the Colorado River system. This symposium, built on two previous decadal scientific meetings, focused on forging scientific consensus where possible, while also 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, with consensus that multidisciplinary studies involving differential incision studies and additional geochronology and thermochronology are needed to test the relative importance of tectonic and geomorphic forcings in shaping the spectacular landscapes of the Colorado Plateau 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 the shaping landscape of elevated plateaus.

  11. 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.

  12. Hydrometallurgical recovery of silver from waste silver oxide button cells

    Energy Technology Data Exchange (ETDEWEB)

    Sathaiyan, N.; Nandakumar, V.; Ramachandran, P. [Central Electrochemical Research Institute, Karaikudi 630 006 (India)

    2006-10-27

    In recent years, recycling of household batteries has attracted much attention mainly with respect to environmental aspects in addition to the savings. Small silver oxide primary cells used in electric watches become a waste after their life is over. Recycling procedures are needed to prevent any environmental impact from these wastes and to recover the value inherent in the scrap. Smelting and electrolytic methods are discussed for silver recovery from this battery waste. Acid leaching of waste batteries and precipitation of silver as silver chloride followed by smelting at 1000{sup o}C yields a silver recovery of about 83%. An electrolytic route is studied as an alternative to the smelting operation and involves the electrodeposition of silver with higher purity from a silver thiosulfate complex prepared from silver chloride. The electrolysis is potentiostatically controlled at a potential of -0.400 to -0.600V (SCE) for avoiding side-reactions such as the sulfiding of silver. Although recovery methods have been identified in principle, their suitability for mixed small battery waste and economic factors have yet to be demonstrated. (author)

  13. 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...

  14. Los 'Colorados': Etnohistoria y Toponimia

    NARCIS (Netherlands)

    J. Gómez-Rendón

    2015-01-01

    Los "colorados" comprendían varios grupos étnicos emparentados etnolingüísticamente que ocupaban el piedemonte andino occidental desde El Carchi hasta Bolívar así como las tierras bajas del Pacífico en los sistemas hidrográficos de los ríos Esmeraldas y Guayas. Aunque la ocupación "colorada" de esta

  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. 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.

  17. 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...

  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. 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.

  20. [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.

  1. 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.

  2. 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…

  3. 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)

  4. Ocular argyrosis secondary to long-term ingestion of silver nitrate salts

    Directory of Open Access Journals (Sweden)

    Olson JL

    2012-12-01

    Full Text Available Kesenia Stafeeva, Michael Erlanger, Raul Velez-Montoya, Jeffrey L OlsonDepartment of Ophthalmology, University of Colorado School of Medicine, Rocky Mountain Lions Eye Institute, Colorado, CO, USAAbstract: This case report describes the clinical, autofluorescence, and optical coherent tomography findings in a patient with panocular argyrosis secondary to chronic intake of diluted silver nitrate salts in his water supply. An 86-year-old Caucasian male with a distinctive gray-bluish hue of the skin presented to our clinic, having developed a slow decrease in visual acuity in both eyes and nyctalopia for the past 2 years. Based on the patient's history of chronic intake of silver nitrate salts and a positive skin biopsy (performed by the dermatology department, data not shown, a diagnosis of panocular argyrosis was made. Fluorescein angiography showed choroidal blockage with a completely dark choroid. Fundus autofluorescence was within normal limits. Optical coherent tomography showed multiple excrescences of retinal pigment epithelium in both eyes. Although the drusen-like changes on fundus examination and retinal pigment epithelium changes may account for the diminished vision, the presence of concomitant nyctalopia suggests underlying damage of the photoreceptors.Keywords: silver nitrate, argyria, ocular argyrosis, fundus autofluorescence, optical coherent tomography

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

    Directory of Open Access Journals (Sweden)

    Sirikamon Saengmee-anupharb

    2013-01-01

    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.

  6. 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...

  7. Silver-Palladium Surfaces Inhibit Biofilm Formation

    DEFF Research Database (Denmark)

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

    2009-01-01

    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...

  8. Increasing influence of air temperature on upper Colorado River streamflow

    Science.gov (United States)

    Woodhouse, Connie A.; Pederson, Gregory T.; Morino, Kiyomi; McAfee, Stephanie A.; McCabe, Gregory

    2016-01-01

    This empirical study examines the influence of precipitation, temperature, and antecedent soil moisture on upper Colorado River basin (UCRB) water year streamflow over the past century. While cool season precipitation explains most of the variability in annual flows, temperature appears to be highly influential under certain conditions, with the role of antecedent fall soil moisture less clear. In both wet and dry years, when flow is substantially different than expected given precipitation, these factors can modulate the dominant precipitation influence on streamflow. Different combinations of temperature, precipitation, and soil moisture can result in flow deficits of similar magnitude, but recent droughts have been amplified by warmer temperatures that exacerbate the effects of relatively modest precipitation deficits. Since 1988, a marked increase in the frequency of warm years with lower flows than expected, given precipitation, suggests continued warming temperatures will be an increasingly important influence in reducing future UCRB water supplies.

  9. 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

  10. 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.

  11. 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...

  12. 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...

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Silver Nafion for Thermogalvanic Applications

    Science.gov (United States)

    Chang, William; Popere, Bhooshan; Evans, Chris; Russ, Boris; Segalman, Rachel

    2015-03-01

    Thermogalvanics convert a temperature gradient, typically from waste heat, into electrical power using a reversible electrochemical reaction. The conversion efficiency in thermogalvanics, like with thermoelectrics, are governed by the Seebeck coefficient, the carrier conductivity and the thermal conductivity of the material. We demonstrate that the material systems silver Nafion and silver poly-styrenesulfonate are air-stable, water processable materials that demonstrate extremely high Seebeck coefficients and moderate carrier conductivities. These power factors, when coupled with the low thermal conductivities inherent in polymers, results in materials with excellent thermogalvanic figure of merits. We show the dependence of these three material properties to material composition and processing. In this talk, we show how the Seebeck coefficient in silver Nafion and silver polystyrene-sulfonate are opposite in sign, allowing construction of a thermogalvanic device. With these ion conductors, we hope to open up a flexible pathway to waste heat recovery using materials typically studied for electrochemical applications.

  19. 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.

  20. 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...

  1. Professional Orientation of Colorado PR Practitioners

    Science.gov (United States)

    Lattimore, Dan L.; And Others

    1974-01-01

    Findings indicate that a majority of public relations practitioners are highly educated, have professional media backgrounds as part of their professional experience, and are paid better than newspaper personnel in Colorado. (RB)

  2. 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...

  3. Comet of the Century

    Science.gov (United States)

    Schaaf, Fred; Ottewell, G.

    The present century has been a disappointing one for comets, but past centuries often featured spectacular, unforgettable comet shows that dominated the night (and even daytime) sky for months: comets that outshone Venus or even the Moon, whose spectacular tails stretched more than halfway across the sky or were weirdly split, and whose apparition was held responsible for everything from wars to unusually good wine vintages. Published to coincide with the first naked-eye appearance of Comet Hale-Bopp, perhaps our own comet of the century, this book is an irresistible guide to comet facts and lore throughout history.

  4. 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)

  5. 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 ...

  6. 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...

  7. 1976 Big Thompson flood, Colorado

    Science.gov (United States)

    Jarrett, R. D.; Vandas, S.J.

    2006-01-01

    In the early evening of July 31, 1976, a large stationary thunderstorm released as much as 7.5 inches of rainfall in about an hour (about 12 inches in a few hours) in the upper reaches of the Big Thompson River drainage. This large amount of rainfall in such a short period of time produced a flash flood that caught residents and tourists by surprise. The immense volume of water that churned down the narrow Big Thompson Canyon scoured the river channel and destroyed everything in its path, including 418 homes, 52 businesses, numerous bridges, paved and unpaved roads, power and telephone lines, and many other structures. The tragedy claimed the lives of 144 people. Scores of other people narrowly escaped with their lives. The Big Thompson flood ranks among the deadliest of Colorado's recorded floods. It is one of several destructive floods in the United States that has shown the necessity of conducting research to determine the causes and effects of floods. The U.S. Geological Survey (USGS) conducts research and operates a Nationwide streamgage network to help understand and predict the magnitude and likelihood of large streamflow events such as the Big Thompson Flood. Such research and streamgage information are part of an ongoing USGS effort to reduce flood hazards and to increase public awareness.

  8. 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.

  9. Paleomagnetism of clastic dikes along the Front Range, Colorado

    Science.gov (United States)

    Dulin, S. A.; Elmore, R. D.

    2011-12-01

    Numerous clastic dikes occur within the Proterozoic basement along nearly 75km of the Front Range of Colorado. These dikes are composed predominately of well-rounded, non-metamorphosed quartz and are red in color due to the abundance of authigenic hematite. The Cambrian Sawatch sandstone is assumed by most studies to be the source of dike sediments due to its similar composition. Despite over a century of study, the origins, age, and emplacement mechanisms of these dikes remain enigmatic. A preliminary paleomagnetic study of the clastic dikes using standard demagnetization techniques indicates the presence of a complex multicomponent magnetization with at least three components. An easterly and moderately steep component residing in hematite was resolved from several dikes and corresponds to an early Cambrian pole position when compared to the apparent polar wander path of North America. An east-southeasterly and shallow magnetization, also residing in hematite, yields a pole of early Paleozoic age. The third component is northwesterly and steep down and is Mesozoic or Cenozoic in age. These results are similar to a previous paleomagnetic study (Kost, MS thesis, Univ. Colorado) in 1984 of different dikes which found poorly defined early and late Paleozoic, as well as Mesozoic-Cenozoic components. Many researchers suggest emplacement occurred during faulting that was associated with either the Ancestral Rockies uplift of the late Paleozoic or the Laramide orogeny of the late Mesozoic/early Cenozoic. The presence of magnetizations of Cambrian age, with subsequent younger remagnetizations, indicates that the emplacement of many of the dikes preceded both of these tectonic events.

  10. Characterisation of decorations on Iranian (10th-13th century) lustreware

    Science.gov (United States)

    Borgia, I.; Brunetti, B.; Giulivi, A.; Sgamellotti, A.; Shokouhi, F.; Oliaiy, P.; Rahighi, J.; Lamehi-Rachti, M.; Mellini, M.; Viti, C.

    It has been recently shown that lustre decoration of Medieval and Renaissance pottery consists of silver and copper nanoparticles, dispersed within the glassy matrix of the ceramic glaze. Lustre surfaces show peculiar optical effects, such as metallic reflection and iridescence. Here we report the findings of a study on lustred glazes of several shards belonging to Iranian pottery of the 10th and 13th centuries, decorated on both sides. Two different glazes, depending on the side of the sample, have been identified. Different lustre chromatic effects are characterised by the relative presence of silver- and copper-metal nanoparticles dispersed in the glassy matrix.

  11. 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.

  12. 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.

  13. 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...

  14. 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...

  15. Century Tide Nicotine Patch

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Century Tide Nicotine Patch, a hi-tech smoking control therapy, is designed in accordance with the scientific principle of nicotine replacement. The therapy is promoted by the World Health Organization. Meanwhile, it also integrates traditional Chinese medical therapy and adopts advanced TTS technology.

  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. 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.

  18. 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.

  19. Characterization of the silver coins of the Hoard of Becin by X-ray based methods

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, M., E-mail: m.rodrigues@akbild.ac.at [Institute of Science and Technology in Art, Academy of Fine Arts, Schillerplatz 3, A-1010 Vienna (Austria); Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna (Austria); Schreiner, M., E-mail: m.schreiner@akbild.ac.at [Institute of Science and Technology in Art, Academy of Fine Arts, Schillerplatz 3, A-1010 Vienna (Austria); Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna (Austria); Melcher, M., E-mail: m.melcher@akbild.ac.at [Institute of Science and Technology in Art, Academy of Fine Arts, Schillerplatz 3, A-1010 Vienna (Austria); Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna (Austria); Guerra, M.; Salomon, J., E-mail: maria.guerra@culture.gouv.fr [Centre de Recherche et de Restauration des Musees de France (C2RMF) - UMR 171, Palais du Louvre - Porte des Lions, 14 quai Francois Mitterrand, 75001 Paris (France); Radtke, M., E-mail: martin.radtke@bam.de [Federal Institute for Materials Research and Testing (BAM), Richard Willstaetter-Strasse 11, 12489 Berlin (Germany); Alram, M., E-mail: michael.alram@khm.at [Coincabinet, Kunsthistorisches Museum, Burgring 5, A-1010 Vienna (Austria); Numismatic Commission, Academy of Sciences, Ignaz-Seipl-Platz 1, A-1010 Vienna (Austria); Schindel, N., E-mail: mikolans.schindel@olaw.oz.at [Numismatic Commission, Academy of Sciences, Ignaz-Seipl-Platz 1, A-1010 Vienna (Austria)

    2011-12-15

    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 ({mu}-XRF, {mu}-SRXRF and {mu}-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.

  20. Plasmonic characterization of photo-induced silver nanoparticles extracted from silver halide based TEM film

    Science.gov (United States)

    Sudheer, Tiwari, P.; Varshney, G. K.; Rai, V. N.; Srivastava, A. K.

    2016-05-01

    The plasmonic responses of silver nanoparticles extracted from silver halide based electron microscope film are investigated. Photo-reduction process is carried out to convert the silver halide grains into the metallic silver. The centrifuge technique is used for separating the silver nanoparticles from the residual solution. Morphological study performed by field emission scanning electron microscope (FESEM) shows that all the nanoparticles have an average diameter of ~120 nm with a high degree of mono dispersion in size. The localized surface plasmon resonance (LSPR) absorption peak at ~537 nm confirms the presence of large size silver nanoparticles.

  1. 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.

  2. 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...

  3. 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.

  4. 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.

  5. 78 FR 47815 - Colorado Disaster # CO-00060

    Science.gov (United States)

    2013-08-06

    ... ADMINISTRATION Colorado Disaster CO-00060 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the... Disaster Assistance, U.S. Small Business Administration, 409 3rd Street SW., Suite 6050, Washington,...

  6. 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....

  7. Is Colorado's Voucher System Worth Vouching for?

    Science.gov (United States)

    Prescott, Brian T.

    2010-01-01

    In 2004 Colorado passed legislation enacting the nation's first voucher-based approach to financing higher education, known as the College Opportunity Fund (COF). The work of an unusual coalition that included higher education leaders, generally conservative policymakers, and others, COF completely replaced the traditional approach of subsidizing…

  8. 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.

  9. The Colorado Plateau: High, Wide, and Windswept.

    Science.gov (United States)

    Booth, Bibi; Brook, Richard; Fischman, Shelly; Jacobson, LouAnn; Smith, Shelley; Tisdale, Mary

    1999-01-01

    Explores the natural forces that created the Colorado Plateau, examines a few of the myriad plants and animals inhabiting the six life zones on the plateau, and provides an overview of the challenges faced by land managers seeking to care for the plateau's extraordinary life and land forms. Contains 17 references. (WRM)

  10. 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…

  11. A Century of Acoustic Metrology

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1998-01-01

    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....

  12. 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...

  13. 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.

  14. 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.

  15. 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.

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

    DEFF Research Database (Denmark)

    Löschner, Katrin; Hadrup, Niels; Qvortrup, Klaus;

    2011-01-01

    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 Ag......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...

  17. 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…

  18. Aquatic Toxicity Comparison of Silver Nanoparticles and Silver Nanowires.

    Science.gov (United States)

    Sohn, Eun Kyung; Johari, Seyed Ali; Kim, Tae Gyu; Kim, Jin Kwon; Kim, Ellen; Lee, Ji Hyun; Chung, Young Shin; Yu, Il Je

    2015-01-01

    To better understand the potential ecotoxicological impact of silver nanoparticles (AgNPs) and silver nanowires (AgNWs) released into freshwater environments, the toxicities of these nanomaterials were assessed and compared using Organization for Economic Cooperation and Development (OECD) test guidelines, including a "Daphnia sp., acute immobilization test," "Fish, acute toxicity test," and "freshwater alga and cyanobacteria, growth inhibition test." Based on the estimated median lethal/effective concentrations of AgNPs and AgNWs, the susceptibility to the nanomaterials was different among test organisms (daphnia > algae > fish), suggesting that the AgNPs are classified as "category acute 1" for Daphnia magna, "category acute 2" for Oryzias latipes, and "category acute 1" for Raphidocelis subcapitata, while the AgNWs are classified as "category acute 1" for Daphnia magna, "category acute 2" for Oryzias latipes, and "category acute 2" for Raphidocelis subcapitata, according to the GHS (Globally Harmonized System of Classification and Labelling of Chemicals). In conclusion, the present results suggest that more attention should be paid to prevent the accidental or intentional release of silver nanomaterials into freshwater aquatic environments. PMID:26125025

  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. 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 ...

  1. 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.

  2. Preparation of silver nanoparticles at low temperature

    Science.gov (United States)

    Mishra, Mini; Chauhan, Pratima

    2016-04-01

    Silver from ancient time is used as antimicrobial agent in the bulk form but now with the advancement in nanotechnology silver in the form of nanoparticles shown potential effect against microbes which make us easy to fight with many diseases plants and animals. In this work silver nanoparticles were synthesized by chemical routes using sodium borohydride as reducing agent at low temperature. The particles were characterized through UV-Visible spectroscopy as well as X-Ray Diffraction. The UV-visible spectra of silver nanoparticles exhibited absorption at 425 cm; the crystallite size of the particles is between 19nm to 39nm. EDAX graph shows two peaks of silver and oxygen. Water absorbed by silver nanoparticles was removed by the calcinations.

  3. 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.

  4. 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...

  5. 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...

  6. Synthesis and optical properties of silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jaiveer [Department of Physics, ISLE, IPS Academy, Rajendra Nagar, Indore 452012, MP (India); Kaurav, Netram, E-mail: netramkaurav@yahoo.co.uk [Department of Physics, Holkar Science College, A-B Road, Indore 452001 (India); Choudhary, K. K. [Department of Physics, National Defence Academy, Khadakwasala, Pune -411023 (India); Okram, Gunadhor S. [Electrical Transport Laboratory, UGC-DAR Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001 (India)

    2015-07-31

    The preparation of stable, uniform silver nanoparticles by reduction of silver acetate by ethylene glycol (EG) is reported in the present paper. It is a simple process of recent interest for obtaining silver nanoparticles. The samples were characterized by X-Ray diffraction (XRD), which reveals an average particle size (D) of 38 nm. The UV/Vis spectra show that an absorption peak, occurring due to surface plasmon resonance (SPR), exists at 319 nm.

  7. 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.

  8. Morphology of a silver/polyacrylonitrile nanocomposite

    Science.gov (United States)

    Kudryashov, M. A.; Mashin, A. I.; Tyurin, A. S.; Fedosov, A. E.; Chidichimo, G.; De Filpo, G.

    2011-01-01

    Silver/polyacrylonitrile (Ag/PAN) nanocomposites are synthesized at the stage of simultaneous acrylonitrile polymerization and the reduction of silver ions from a mixture of silver nitrate AgNO3, acrylonitrile, and a photoinitiator. The synthesized films are transparent in the visible region and are characterized by a uniform dispersion of silver nanoparticles in a PAN matrix without any macroscopic agglomeration. The effects of the metal salt and photoinitiator concentrations on the size and density of metal nanoparticles in a composite are revealed.

  9. 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.

  10. Salinity in the Colorado River in the Grand Valley, western Colorado, 1994-95

    Science.gov (United States)

    Butler, David L.; von Guerard, Paul B.

    1996-01-01

    Salinity, or the dissolved-solids concentration, is the measure of salts such as sodium chloride, calcium bicarbonate, and calcium sulfate that are dissolved in water. About one-half of the salinity in the Colorado River Basin is from natural sources (U.S. Department of the Interior, 1995), such as thermal springs in the Glenwood-Dotsero area, located about 90 miles upstream from Grand Junction (fig. 1). Effects of human activities, such as irrigation, reservoir evaporation, and transbasin diversions, have increased the levels of salinity in the Colorado River. High salinity can affect industrial and municipal water users by causing increased water-treatment costs, increased deterioration of plumbing and appliances, increased soap needs, and undesirable taste of drinking water. High salinity also can cause lower crop yields by reducing water and nutrient uptake by plants and can increase agricultural production costs because of higher leaching and drainage requirements. Agricultural losses might occur when salinity reaches about 700?850 milligrams per liter (U.S Department of the Interior, 1994). Figure 1. Irrigated area in the Grand Valley and locations of sampling sites for the 1994?95 salinity study of the Colorado River. The Colorado River is the major source of irrigation water to the Grand Valley (fig. 1) and also is one source of water for the Clifton Water District, which supplies domestic water to part of the eastern Grand Valley. During spring and early summer in 1994, the Colorado River in the Grand Valley had lower than average streamflow. There was concern by water users about the effect of this low streamflow on salinity in the river. In 1994, the U.S. Geological Survey (USGS), in cooperation with the Colorado River Water Conservation District, began a study to evaluate salinity in the Colorado River. This fact sheet describes results of that study. The specific objectives of the fact sheet are to (1) compare salinity in the Colorado River among

  11. 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.

  12. 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

  13. 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

  14. 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...

  15. 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.

  16. 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 ...

  17. 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.

  18. 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

  19. Antibacterial activities of silver nanoparticles and antibiotic-adsorbed silver nanoparticles against biorecycling microbes.

    Science.gov (United States)

    Khurana, Chandni; Vala, Anjana K; Andhariya, Nidhi; Pandey, O P; Chudasama, Bhupendra

    2014-09-20

    Silver nanoparticles have a huge share in nanotechnology based products used in clinical and hygiene products. Silver nanoparticles leaching from these medical and domestic products will eventually enter terrestrial ecosystems and will interact with the microbes present in the land and water. These interactions could be a threat to biorecycling microbes present in the Earth's crust. The antimicrobial action towards biorecycling microbes by leached silver nanoparticles from medical waste could be many times greater compared to that of silver nanoparticles leached from other domestic products, since medical products may contain traditional antibiotics along with silver nanoparticles. In the present article, we have evaluated the antimicrobial activities of as-synthesized silver nanoparticles, antibiotics - tetracycline and kanamycin, and antibiotic-adsorbed silver nanoparticles. The antimicrobial action of silver nanoparticles with adsorbed antibiotics is 33-100% more profound against the biorecycling microbes B. subtilis and Pseudomonas compared to the antibacterial action of silver nanoparticles of the same concentration. This study indicates that there is an immediate and urgent need for well-defined protocols for environmental exposure to silver nanoparticles, as the use of silver nanoparticles in nanotechnology based products is poorly restricted.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. The Silver Export Quota for 2005

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    <正>China’s Ministry of Commerce recently announced the first lot of silver export quota for 2005. According to report, the first lot of silver export quota amounts to 2,443 tons which is 252 tons more on 2004 basis. There are 37 en-

  7. Intravesical silver nitrate for refractory hemorrhagic cystitis

    Science.gov (United States)

    Montgomery, Brian D.; Boorjian, Stephen A.; Ziegelmann, Matthew J.; Joyce, Daniel D.; Linder, Brian J.

    2016-01-01

    Objective Hemorrhagic cystitis is a challenging clinical entity with limited evidence available to guide treatment. The use of intravesical silver nitrate has been reported, though supporting literature is sparse. Here, we sought to assess outcomes of patients treated with intravesical silver nitrate for refractory hemorrhagic cystitis. Material and methods We identified nine patients with refractory hemorrhagic cystitis treated at our institution with intravesical silver nitrate between 2000–2015. All patients had failed previous continuous bladder irrigation with normal saline and clot evacuation. Treatment success was defined as requiring no additional therapy beyond normal saline irrigation after silver nitrate instillation prior to hospital discharge. Results Median patient age was 80 years (IQR 73, 82). Radiation was the most common etiology for hemorrhagic cystitis 89% (8/9). Two patients underwent high dose (0.1%–0.4%) silver nitrate under anesthesia, while the remaining seven were treated with doses from 0.01% to 0.1% via continuous bladder irrigation for a median of 3 days (range 2–4). All nine patients (100%) had persistent hematuria despite intravesical silver nitrate therapy, requiring additional interventions and red blood cell transfusion during the hospitalization. There were no identified complications related to intravesical silver nitrate instillation. Conclusion Although well tolerated, we found that intravesical silver nitrate was ineffective for bleeding control, suggesting a limited role for this agent in the management of patients with hemorrhagic cystitis. PMID:27635296

  8. 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

  9. 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

  10. 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)

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    Dominik Kulakowski

    Full Text Available 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

  4. 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

  5. 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.

  6. 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...

  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. 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…

  9. 78 FR 19296 - Notice of Inventory Completion: History Colorado, formerly Colorado Historical Society, Denver, CO

    Science.gov (United States)

    2013-03-29

    ... of History Colorado, Denver, CO. The human remains were removed from Suncor Energy USA Pipeline... individual were removed from Suncor Energy USA Pipeline Company property in Adams County, CO. The human remains were discovered while Suncor was excavating a trench as part of mitigation efforts concerning...

  10. 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…

  11. 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...

  12. 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...

  13. 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...

  14. 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

  15. 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

  16. 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.

  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. Anti-bacterial Studies of Silver Nanoparticles

    CERN Document Server

    Theivasanthi, T

    2011-01-01

    We discuss about the antibacterial activities of Silver nanoparticles and compare them on both Gram negative and Gram positive bacteria in this investigation. The activities of Silver nanoparticles synthesized by electrolysis method are more in Gram (-) than Gram (+) bacteria. First time, we increase its antibacterial activities by using electrical power while on electrolysis synthesis and it is confirmed from its more antibacterial activities (For Escherichia coli bacteria). We investigate the changes of inner unit cell Lattice constant of Silver nanoparticles prepared in two different methods and its effects on antibacterial activities. We note that slight change of the lattice constant results in the enhancement of its antibacterial activities.

  19. 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%.

  20. 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.

  1. 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...

  2. 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...

  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. Two Possible Configurations for Silver-C60-Silver Molecular Devices and Their Conductance Characteristics

    Institute of Scientific and Technical Information of China (English)

    TIAN Guang-Jun; SU Wen-Yong

    2009-01-01

    Coherent electronic transport properties of silver-C60-silver molecular junctions in different configurations are studied using hybrid density function theory.The experimentally measured current flows of C60 molecules adsorbed on the diver surface are well reproduced by theoretical calculations.It is found that the current-voltage characteristics of the molecular junctions depend strongly on the configurations of the junctions.Transmission spectra combined with density of states can help us to understand in depth the transport properties.Different kinds of electrode construction are also discussed.With the help of the calculation,two possible configurations of silver-C60-silver molecular junctions are suggested.

  6. Sixteenth Century Astronomical Telescopy

    Science.gov (United States)

    Usher, P. D.

    2001-12-01

    Ophelia in Shakespeare's Hamlet is named for the ``moist star" which in mythology is the partner of Hamlet's royal Sun. Together the couple seem destined to rule on earth just as their celestial counterparts rule the heavens, but the tragedy is that they are afflicted, just as the Sun and Moon are blemished. In 1.3 Laertes lectures Ophelia on love and chastity, describing first Cytherean phases (crescent to gibbous) and then Lunar craters. Spots mar the Sun (1.1, 3.1). Also reported are Jupiter's Red Spot (3.4) and the resolution of the Milky Way into stars (2.2). These interpretations are well-founded and support the cosmic allegory. Observations must have been made with optical aid, probably the perspective glass of Leonard Digges, father of Thomas Digges. Notably absent from Hamlet is mention of the Galilean moons, owing perhaps to the narrow field-of-view of the telescope. That discovery is later celebrated in Cymbeline, published soon after Galileo's Siderius Nuncius in 1610. In 5.4 of Cymbeline the four ghosts dance ``in imitation of planetary motions" and at Jupiter's behest place a book on the chest of Posthumus Leonatus. His name identifies the Digges father and son as the source of data in Hamlet since Jupiter's moons were discovered after the deaths of Leonard (``leon+hart") and Thomas (the ``lion's whelp"). Lines in 5.4 urge us not to read more into the book than is contained between its covers; this is understandable because Hamlet had already reported the other data in support of heliocentricism and the cosmic model discussed and depicted by Thomas Digges in 1576. I conclude therefore that astronomical telescopy began in England before the last quarter of the sixteenth century.

  7. 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.

  8. 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.

  9. Mechanisms of Silver Nanoparticle Toxicity

    DEFF Research Database (Denmark)

    Foldbjerg, Rasmus

    The rapidly growing field of nanotechnology holds great promise for scientific advancement in many sectors such as medicine, consumer products, energy, and materials. In general terms, nanotechnology covers engineered structures, devices, and systems that have a length scale between 1 and 100...... nanometers. At this size, materials begin to exhibit unique properties that affect physical, chemical, and biological behavior. However, the same characteristics which make nanomaterials attractive for exploitation in new products have led to concerns that nanomaterials may pose a risk for humans...... related to the response caused by Ag NPs, our findings suggested that Ag NPs, due to their particulate form, affect exposed cells in a more complex way than silver ions....

  10. 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.

  11. 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.

  12. 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.

  13. 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...

  14. 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

  15. 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.

  16. In situ SU-8 silver nanocomposites

    DEFF Research Database (Denmark)

    Fischer, Søren Vang; Uthuppu, Basil; Jakobsen, Mogens Havsteen

    2015-01-01

    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...... silver nanocomposite materials can be spin coated as homogeneous thin films and structured by using UV lithography. A resolution of 5 mu m is achieved in the lithographic process. The UV exposure time is found to be independent of the nanoparticle concentration. The fabricated silver nanocomposites...

  17. 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

  18. Electrolytic silver ion cell sterilizes water supply

    Science.gov (United States)

    Albright, C. F.; Gillerman, J. B.

    1968-01-01

    Electrolytic water sterilizer controls microbial contamination in manned spacecraft. Individual sterilizer cells are self-contained and require no external power or control. The sterilizer generates silver ions which do not impart an unpleasant taste to water.

  19. 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

  20. 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

  1. 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)

  2. Gold and Silver Extraction from Leach Solutions

    Directory of Open Access Journals (Sweden)

    Bagdaulet K. Kenzhaliyev

    2014-03-01

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

  3. 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.

  4. '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

  5. 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 nanomate......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...

  6. 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...... sensitive to any perturbation, particularly caused by temperature. We analyze and characterize the morphological transition both in time and temperature using the recently developed Monte Carlo simulation approach for the description of nanofractal dynamics and compare the obtained results...

  7. 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...

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

    Science.gov (United States)

    Bianco, Carlotta; Kezic, Sanja; Crosera, Matteo; Svetličić, Vesna; Šegota, Suzana; Maina, Giovanni; Romano, Canzio; Larese, Francesca; Adami, Gianpiero

    2015-01-01

    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/cm(2)), fitting the bactericidal range. Silver and silver chloride aggregates at sizes of up to 1 μm were identified both in the epidermis and dermis. The large size of these particles suggests that the aggregation occurred in the skin. The formation of these aggregates likely slowed down the systemic absorption of silver. Conversely, these aggregates may form a reservoir enabling prolonged release of silver ions, which might lead to local effects.

  9. Pulsed EPR for studying silver clusters

    Energy Technology Data Exchange (ETDEWEB)

    Michalik, J.; Wasowicz, T.; Sadlo, J. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland); Reijerse, E.J. [Katholieke Univ., Nijmegen (Netherlands). Dept. of Molecular Spectroscopy; Kevan, L. [Texas Univ., Houston, TX (United States). Dept. of Chemistry

    1996-01-01

    The cationic silver clusters of different nuclearity have been produced by radiolysis of zeolite A and SAPO molecular sieves containing Ag{sup +} 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{sub 6}{sup n+} cluster in dehydration zeolite A indicate that the hexameric silver is stabilized only in sodalite cages which are surrounded by {alpha}-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{sub 4}{sup n+} in SAPO-42 is stabilized in {alpha} cages, where it is directly coordinated by two methanol molecules. Dimeric silver, Ag{sub 2}{sup +} in SAPO-5 and SAPO-11 is located in 6-ring channels and interacts with three CH{sub 3}OH molecules, each in different 10 ring or 12 ring channels. The differences of Ag{sub 2}{sup +} stability in SAPO-5 and SAPO-11 are also discussed. (Author).

  10. 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.

  11. 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.

  12. 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)

  13. [In vitro percutaneous absorption of silver nanoparticles].

    Science.gov (United States)

    Filon, F Larese; D'Agostin, F; Crosera, M; Adami, G; Rosani, R; Romano, C; Bovenzi, M; Maina, G

    2007-01-01

    There is a growing interest in the debate on nanoparticle safety for topical use. The benefits of nanoparticles have been shown in several scientific fields, but little is known about their potential to penetrate the skin lies. This study aims at evaluating in vitro silver nanoparticles skin penetration. Experiments were performed using the Franz diffusion cell method with intact and damaged human skin. Physiological solution was used as receiving phase and 70 microg/cm2 of silver nanoparticles dispersed in synthetic sweat were applied as donor phase to the outer surface of the skin for 24h. The receptor fluid measurements were performed by Electro Thermal Atomic Absorption Spectroscopy (ETAAS). Silver concentration of 0.2 microg/L was found in the receiving solutions of two cells, in which damaged skin membranes were set up. In the other tests, we obtained a silver concentration below the limit of detection in the receiving cells. Our experimental data show that silver nanoparticles permeation through intact and damaged skin is negligible. These findings are consistent with previously published results. Further researches are necessary to explore skin absorption of silver nanoparticles.

  14. Conifer health classification for Colorado, 2008

    Science.gov (United States)

    Cole, Christopher J.; Noble, Suzanne M.; Blauer, Steven L.; Friesen, Beverly A.; Curry, Stacy E.; Bauer, Mark A.

    2010-01-01

    Colorado has undergone substantial changes in forests due to urbanization, wildfires, insect-caused tree mortality, and other human and environmental factors. The U.S. Geological Survey Rocky Mountain Geographic Science Center evaluated and developed a methodology for applying remotely-sensed imagery for assessing conifer health in Colorado. Two classes were identified for the purposes of this study: healthy and unhealthy (for example, an area the size of a 30- x 30-m pixel with 20 percent or greater visibly dead trees was defined as ?unhealthy?). Medium-resolution Landsat 5 Thematic Mapper imagery were collected. The normalized, reflectance-converted, cloud-filled Landsat scenes were merged to form a statewide image mosaic, and a Normalized Difference Vegetation Index (NDVI) and Renormalized Difference Infrared Index (RDII) were derived. A supervised maximum likelihood classification was done using the Landsat multispectral bands, the NDVI, the RDII, and 30-m U.S. Geological Survey National Elevation Dataset (NED). The classification was constrained to pixels identified in the updated landcover dataset as coniferous or mixed coniferous/deciduous vegetation. The statewide results were merged with a separate health assessment of Grand County, Colo., produced in late 2008. Sampling and validation was done by collecting field data and high-resolution imagery. The 86 percent overall classification accuracy attained in this study suggests that the data and methods used successfully characterized conifer conditions within Colorado. Although forest conditions for Lodgepole Pine (Pinus contorta) are easily characterized, classification uncertainty exists between healthy/unhealthy Ponderosa Pine (Pinus ponderosa), Pi?on (Pinus edulis), and Juniper (Juniperus sp.) vegetation. Some underestimation of conifer mortality in Summit County is likely, where recent (2008) cloud-free imagery was unavailable. These classification uncertainties are primarily due to the spatial and

  15. Controlled growth of large-scale silver nanowires

    Institute of Scientific and Technical Information of China (English)

    Xiao Cong-Wen; Yang Hai-Tao; Shen Cheng-Min; Li Zi-An; Zhang Huai-Ruo; Liu Fei; Yang Tian-Zhong; Chen Shu-Tang; Gao Hong-Jun

    2005-01-01

    Large-scale silver nanowires with controlled aspect ratio were synthesized via reducing silver nitrate with 1, 2-propanediol in the presence of poly (vinyl pyrrolidone) (PVP). Scanning electron microscopy, transmission electron microscopy and x-ray powder diffraction were employed to characterize these silver nanowires. The diameter of the silver nanowires can be readily controlled in the range of 100 to 400 nm by varying the experimental conditions. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy results show that there exists no chemical bond between the silver and the nitrogen atoms. The interaction between PVP and silver nanowires is mainly through the oxygen atom in the carbonyl group.

  16. 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.

  17. 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

  18. Environmental Setting and Implications on Water Quality, Upper Colorado River Basin, Colorado and Utah

    Science.gov (United States)

    Apodaca, Lori E.; Driver, Nancy E.; Stephens, Verlin C.; Spahr, Norman E.

    1995-01-01

    The Upper Colorado River Basin in Colorado and Utah is 1 of 60 study units selected for water-quality assessment as part of the U.S. Geological Survey's National Water-Quality Assessment program, which began full implementation in 1991. Understanding the environmental setting of the Upper Colorado River Basin study unit is important in evaluating water-quality issues in the basin. Natural and human factors that affect water quality in the basin are presented, including an overview of the physiography, climatic conditions, general geology and soils, ecoregions, population, land use, water management and use, hydrologic characteristics, and to the extent possible aquatic biology. These factors have substantial implications on water-quality conditions in the basin. For example, high concentrations of dissolved solids and selenium are present in the natural background water conditions of surface and ground water in parts ofthe basin. In addition, mining, urban, and agricultural land and water uses result in the presence of certain constituents in the surface and ground water of the basin that can detrimentally affect water quality. The environmental setting of the study unit provides a framework of the basin characteristics, which is important in the design of integrated studies of surface water, ground water, and biology.

  19. 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...

  20. 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.

  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. US hydropower resource assessment for Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Francfort, J.E.

    1994-05-01

    The US Department of Energy is developing an estimate of the hydropower development potential in this country. Hydropower Evaluation Software (HES) is a computer model that was developed by the Idaho National Engineering Laboratory for this purpose. HES measures the potential hydropower resources available in the United States, using uniform criteria for measurement. The software was developed and tested using hydropower information and data provided by the Southwestern Power Administration. It is a dBASE, menu-driven software application. HES allows the personal computer user to assign environmental attributes to potential hydropower sites, calculate development suitability factors for each site based on the environmental attributes present, and generate reports based on these suitability factors. This report details the resource assessment results for the State of Colorado.

  3. Silver nanoparticles incorporated onto ordered mesoporous silica from Tollen's reagent

    Science.gov (United States)

    Zienkiewicz-Strzałka, M.; Pasieczna-Patkowska, S.; Kozak, M.; Pikus, S.

    2013-02-01

    Noble metal nanostructures supported on mesoporous silica are bridge between traditional silica adsorbents and modern catalysts. In this work the Ag/SBA-15 mesoporous materials were synthesized and characterized. Various forms of nanosilver supported on ordered mesoporous template have been successfully obtained via proposed procedures. In all synthesized materials, Tollen's reagent (diammine silver complex [Ag(NH3)2]+) was used as a silver source. Silver nanoparticles were prepared by reduction of ammoniacal silver complex by formaldehyde in the solution of stabilizer. After reduction, Ag nanoparticles could be deposited on SBA-15, or added during traditional synthesis of SBA-15 giving silver or silver chloride nanoparticles in the combination with porous silica. Silver nanostructures as nanoparticles or nanowires were also embedded onto the SBA-15 by incipient wetness impregnation of silver ions. Absorbed silver ions were next reduced under hydrogen at high temperature. There are many advantages of utilized ammoniacal silver complex as a silver source. Proposed method is capable to synthesis of various metal nanostructures with controlled composition and morphology. The silver ammonia complex is composed of two ions surrounding and protecting the central silver ion, so it is possible to obtain very small nanoparticles using simple approach without any functionalization of external and internal surface of SBA-15. This approach allows obtaining greatly small silver nanoparticles on SBA-15 (4 nm) or nanowires depending on the metal loading amount. Moreover, the colloidal silver solution prepared from Tollen's reagent, in the presence of triblock copolymer, remains stable for a long time. Reduction of Tollen's reagent to silver colloidal solution seems to be efficient, fast and interesting approach for the preparation of supported silver nanostructures Obtained samples were characterized by powder X-ray diffraction, small angle X-ray scattering (SAXS), UV

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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....

  12. Colorado cultural resource survey: Management data form [5JA784

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document includes the survey forms necessary to assess cultural resources in Colorado. This document assesses the Allard Ranch (site # 5JA784, temporary #...

  13. 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...

  14. 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.

  15. 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...

  16. Mahogany Ledge Digital Line Outcrop of the Piceance Basin, Colorado

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Mahogany ledge outcrop was needed to limit resource calculations in the Piceance Basin, Colorado as part of a 2009 National Oil Shale Assessment.

  17. 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

  18. 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)

  19. 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.

  20. Silver nanowire decorated heatable textiles.

    Science.gov (United States)

    Doganay, Doga; Coskun, Sahin; Genlik, Sevim Polat; Unalan, Husnu Emrah

    2016-10-28

    The modification of insulating fabrics with electrically conductive nanomaterials has opened up a novel application field. With the help of Joule heating mechanism, conductive fabrics can be used as mobile heaters. In this work, heatable textiles are fabricated using silver nanowires (Ag NWs). Cotton fabrics are decorated with polyol synthesized Ag NWs via a simple dip-and-dry method. The time-dependent thermal response of the fabrics under different applied voltages is investigated. It is found that the fabrics can be heated to 50 °C under an applied power density of as low as 0.05 W cm(-2). Uniform deposition of Ag NWs resulted in the homogeneous generation of heat. In addition, the stability of the fabrics with time and under different bending and washing conditions is examined. Moreover, a simple control circuit is fabricated and integrated in order to demonstrate the high potential of the fabrics for mobile applications. This work provides a roadmap for researchers who would like to work on heatable textiles with metallic NWs. PMID:27651222

  1. 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.

  2. 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...

  3. 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

  4. 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...

  5. Use of ferricyanide for gold and silver cyanidation

    Institute of Scientific and Technical Information of China (English)

    F. XIE; D. B. DREISINGER

    2009-01-01

    Low gold and silver leaching kinetics has been commonly observed in traditional gold-silver cyanidation process, especially in heap leaching and in situ leaching operations. The different mineralogy of gold and silver in the ores is suspected to be the main reason, e.g., the occurrence of low solubility acanthite (Ag2S) typically results in low overall silver extraction. Due to the low solubility of oxygen in cyanide solution, the reactivity and availability of oxidant is believed to be the critical limitation for gold and silver dissolution. The use of ferricyanide as the auxiliary oxidant for gold and silver cyanidation has been examined. The rotating disc test results prove the assistant effect of ferricyanide on increasing the dissolution rate of gold and silver. The potential use of ferricyanide in gold/silver cyanidation process is proposed based on the leaching results of actual ores.

  6. 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.

  7. Ink composition for making a conductive silver structure

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Steven B.; Lewis, Jennifer A.

    2016-10-18

    An ink composition for making a conductive silver structure comprises a silver salt and a complex of (a) a complexing agent and a short chain carboxylic acid or (b) a complexing agent and a salt of a short chain carboxylic acid, according to one embodiment. A method for making a silver structure entails combining a silver salt and a complexing agent, and then adding a short chain carboxylic acid or a salt of the short chain carboxylic acid to the combined silver salt and a complexing agent to form an ink composition. A concentration of the complexing agent in the ink composition is reduced to form a concentrated formulation, and the silver salt is reduced to form a conductive silver structure, where the concentrated formulation and the conductive silver structure are formed at a temperature of about 120.degree. C. or less.

  8. Alzheimer’s disease:the silver tsunami of the 21st century

    Institute of Scientific and Technical Information of China (English)

    Ankita Sarkar; Madison Irwin; Aditi Singh; Matthew Riccetti; Amit Singh

    2016-01-01

    Alzheimer’s disease (AD), a fatal progressive neurodegenerative disorder, has no cure to date. One of the causes of AD is the accumulation of amyloid-beta 42 (Aβ42) plaques, which result in the onset of neuro-degeneration. It is not known how these plaques trigger the onset of neurodegeneration. There are several animal models developed to (i) study etiology of disease, (ii) look for genetic modiifers, and (iii) identify chemical inhibitors that can block neurodegeneration and help to find cure for this disease. An insect model ofDrosophila melanogasterhas also provided new insights into the disease. Here we will discuss the utility of theDrosophila eye model to study Alzheimer’s disease.

  9. 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.

  10. 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

  11. 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.

  12. 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 ...

  13. 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...

  14. 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...

  15. 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...

  16. 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

  17. 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.

  18. Ground-based Investigations of Atomic Oxygen Erosion Behaviors of Silver and Ion-implanted Silver

    Institute of Scientific and Technical Information of China (English)

    DUO Shu-wang; LI Mei-shuan; YIN Xiao-hui; LI Wen-kui; LI Ming-sheng

    2006-01-01

    Silver foils and ion-implanted silver foils exposed to atomic oxygen (AO) generated in a ground simulation facility were investigated by the quartz crystal microbalance (QCM), the scanning electron microscopy (SEM) and the X-ray photoelectron spectroscopy (XPS). The experimental results show the presence of Ag2O and AgO in an oxidation process of the silver foil having exposure to AO. As soon as silver comes under the bombardment of atomic oxygen, the oxidation process starts with a thick film forming on the silver surface. Because of the development of stresses, the oxide layer gets cracked and spalled, which leads to appearance of a new silver surface intensifying further oxidation. At last, AgO begins to form on the outer surface of the oxide film. The analytical results of the XPS and the AES attest to formation of a continuous high-quality protective oxide-based layer on the surface of ion-implanted silver films after exposure to AO. This layer can well protect materials in question from erosion.

  19. [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

  20. 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...

  1. Propagation of plasmons in designed single crystalline silver nanostructures

    DEFF Research Database (Denmark)

    Kumar, Shailesh; Lu, Ying-Wei; Huck, Alexander;

    2012-01-01

    We demonstrate propagation of plasmons in single crystalline silver nanostructures fabricated using a combination of a bottom-up and a top-down approach. Silver nanoplates of thickness around 65 nm and a surface area of about 100 μm2 are made using a wet chemical method. Silver nanotips and nanow...

  2. 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.

  3. 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…

  4. 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

  5. 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...

  6. Nanosecond laser ablation of silver nanoparticle film

    Science.gov (United States)

    Chung, Jaewon; Han, Sewoon; Lee, Daeho; Ahn, Sanghoon; Grigoropoulos, Costas P.; Moon, Jooho; Ko, Seung H.

    2013-02-01

    Nanosecond laser ablation of polyvinylpyrrolidone (PVP) protected silver nanoparticle (20 nm diameter) film is studied using a frequency doubled Nd:YAG nanosecond laser (532 nm wavelength, 6 ns full width half maximum pulse width). In the sintered silver nanoparticle film, absorbed light energy conducts well through the sintered porous structure, resulting in ablation craters of a porous dome shape or crown shape depending on the irradiation fluence due to the sudden vaporization of the PVP. In the unsintered silver nanoparticle film, the ablation crater with a clean edge profile is formed and many coalesced nanoparticles of 50 to 100 nm in size are observed inside the ablation crater. These results and an order of magnitude analysis indicate that the absorbed thermal energy is confined within the nanoparticles, causing melting of nanoparticles and their coalescence to larger agglomerates, which are removed following melting and subsequent partial vaporization.

  7. 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.

  8. 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.

  9. 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

  10. Geologic map of Colorado National Monument and adjacent areas, Mesa County, Colorado

    Science.gov (United States)

    Scott, Robert B.; Harding, Anne E.; Hood, William C.; Cole, Rex D.; Livaccari, Richard F.; Johnson, James B.; Shroba, Ralph R.; Dickerson, Robert P.

    2001-01-01

    New 1:24,000-scale geologic mapping in the Colorado National Monument Quadrangle and adjacent areas, in support of the USGS Western Colorado I-70 Corridor Cooperative Geologic Mapping Project, provides new interpretations of and data for the stratigraphy, structure, geologic hazards in the area from the Colorado River in Grand Valley onto the Uncompahgre Plateau. The plateau drops abruptly along northwest-trending structures toward the northeast 800 m to the Redlands area and the Colorado River in Grand Valley. In addition to common alluvial and colluvial deposits, surficial deposits include Holocene and late Pleistocene charcoal-bearing valley-fill deposits, late to middle Pleistocene river-gravel terrace deposits, Holocene to middle Pleistocene younger, intermediate, and old fan-alluvium deposits, late to middle Pleistocene local gravel deposits, Holocene to late Pleistocene rock-fall deposits, Holocene to middle Pleistocene young and old landslide deposits, Holocene to late Pleistocene sheetwash deposits and eolian deposits, and Holocene Cienga-type deposits. Only the lowest part of the Upper Cretaceous Mancos Shale is exposed in the map area near the Colorado River. The Upper and Lower? Cretaceous Dakota Formation and the Lower Cretaceous Burro Canyon Formation form resistant dipslopes in the Grand Valley and a prominent ridge on the plateau. Less resistant strata of the Upper Jurassic Morrison Formation consisting of the Brushy Basin, Salt Wash, and Tidwell Members form slopes on the plateau and low areas below the mountain front of the plateau. The Middle Jurassic Wanakah Formation nomenclature replaces the previously used Summerville Formation. Because an upper part of the Middle Jurassic Entrada Formation is not obviously correlated with strata found elsewhere, it is therefore not formally named; however, the lower rounded cliff former Slickrock Member is clearly present. The Lower Jurassic silica-cemented Kayenta Formation forms the cap rock for the Lower

  11. 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...

  12. 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

  13. 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.

  14. Summary of the mineralogy of the Colorado Plateau uranium ores

    Science.gov (United States)

    Weeks, Alice D.; Coleman, Robert Griffin; Thompson, Mary E.

    1956-01-01

    In the Colorado Plateau uranium has been produced chiefly from very shallow mines in carnotite ores (oxidized vanadiferous uranium ores) until recent deeper mining penetrated black unoxidized ores in water-saturated rocks and extensive exploration has discovered many deposits of low to nonvanadiferous ores. The uranium ores include a wide range from highly vanadiferous and from as much as one percent to a trace of copper, and contain a small amount of iron and traces of lead, zinc, molybdenum, cobalt, nickel, silver, manganese, and other metals. Recent investigation indicates that the carnotite ores have been derived by progressive oxidation of primary (unoxidized) black ores that contain low-valent uranium and vanadium oxides and silicates. The uranium minerals, uraninite and coffinite, are associated with coalified wood or other carbonaceous material. The vanadium minerals, chiefly montroseite, roscoelite, and other vanadium silicates, occur in the interstices of the sandstone and in siltstone and clay pellets as well as associated with fossil wood. Calcite, dolomite, barite and minor amounts of sulfides, arsenides, and selenides occur in the unoxidized ore. Partially oxidized vanadiferous ore is blue black, purplish brown, or greenish black in contrast to the black or dark gray unoxidized ore. Vanadium combines with uranium to form rauvite. The excess vanadium is present in corvusite, fernandinite, melanovanadite and many other quadrivalent and quinquevalent vanadium minerals as well as in vanadium silicates. Pyrite and part or all of the calcite are replaced by iron oxides and gypsum. In oxidized vanadiferous uranium ores the uranium is fixed in the relatively insoluble minerals carnotite and tyuyamunite, and the excess vanadium commonly combines with one or more of the following: calcium, sodium, potassium, magnesium, aluminum, iron, copper, manganese, or barium, or rarely it forms the hydrated pentoxide. The relatively stable vanadium silicates are little

  15. 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...

  16. 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...

  17. 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.

  18. 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

  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. Manufacturing of superconductive silver/ceramic composites

    DEFF Research Database (Denmark)

    Seifi, Behrouz; Bech, Jakob Ilsted; Eriksen, Morten;

    2000-01-01

    Manufacturing of superconducting metal/ceramic composites is a rather new discipline within materials forming processes. High Temperature SuperConductors, HTSC, are manufactured applying the Oxide-Powder-In-Tube process, OPIT. A ceramic powder containing lead, calcium, bismuth, strontium......, and 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...

  1. 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.

  2. 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

  3. 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'...

  4. Talladega College: The First Century.

    Science.gov (United States)

    Jones, Maxine D.; Richardson, Joe M.

    The book presents the history of the growth, development, and significance of Alabama's Talladega College, a black liberal arts college, from its inception in the 1860s through the student protest movement more than a century later. The historical account emphasizes such college issues as finance, enrollment, students, educational policy, and the…

  5. 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.

  6. Effects of surface applications of biosolids on soil, crops, ground water, and streambed sediment near Deer Trail, Colorado, 1999-2003

    Science.gov (United States)

    Yager, Tracy J.B.; Smith, David B.; Crock, James G.

    2004-01-01

    The U.S. Geological Survey, in cooperation with Metro Wastewater Reclamation District and North Kiowa Bijou Groundwater Management District, studied natural geochemical effects and the effects of biosolids applications to the Metro Wastewater Reclamation District properties near Deer Trail, Colorado, during 1999 through 2003 because of public concern about potential contamination of soil, crops, ground water, and surface water from biosolids applications. Parameters analyzed for each monitoring component included arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium, and zinc (the nine trace elements regulated by Colorado for biosolids), gross alpha and gross beta radioactivity, and plutonium, as well as other parameters. Concentrations of the nine regulated trace elements in biosolids were relatively uniform and did not exceed applicable regulatory standards. All plutonium concentrations in biosolids were below the minimum detectable level and were near zero. The most soluble elements in biosolids were arsenic, molybdenum, nickel, phosphorus, and selenium. Elevated concentrations of bismuth, mercury, phosphorus, and silver would be the most likely inorganic biosolids signature to indicate that soil or streambed sediment has been affected by biosolids. Molybdenum and tungsten, and to a lesser degree antimony, cadmium, cobalt, copper, mercury, nickel, phosphorus, and selenium, would be the most likely inorganic 'biosolids signature' to indicate ground water or surface water has been affected by biosolids. Soil data indicate that biosolids have had no measurable effect on the concentration of the constituents monitored. Arsenic concentrations in soil of both Arapahoe and Elbert County monitoring sites (like soil from all parts of Colorado) exceed the Colorado soil remediation objectives and soil cleanup standards, which were determined by back-calculating a soil concentration equivalent to a one-in-a-million cumulative cancer risk. Lead concentrations

  7. Geology of the Gypsum Gap quadrangle, Colorado

    Science.gov (United States)

    Cater, Fred W.

    1953-01-01

    The Gypsum Gap quadrangle is one eighteen 7 1/2-minute quadrangles covering the principal carnotite-producing area of southwestern Colorado. The geology of these quadrangles was mapped by the U.S. Geological Survey for the Atomic Energy Commission as part of a comparative study of carnotite deposits. The rocks exposed in the eighteen quadrangles consist of crystalline rocks of pre-Cambrian age and sedimentary rocks that range in age from late Paleozoic to Quaternary. Over much of the area the sedimentary rocks are flat lying, but in places the rocks are disrupted by high-angle faults, and northwest-trending folds. Conspicuous among the folds are large anticlines having cores of intrusive salt and gypsum. Most of the carnotite deposits are confined to the Salt Wash sandstone member of the Jurassic Morrison formation. Within this sandstone, most of the deposits are spottily distributed through a arcuate zone known as the "Uravan Mineral Belt". Individual deposits range in size from irregular masses containing only a few tons of ore to large, tabular masses containing many thousands of tons. The core consists largely of sandstone selectively impregnated and in part replaced by uranium and vanadium minerals. Most of the deposits appear to be related to certain sedimentary structures in sandstones of favorable composition.

  8. Geology of the Davis Mesa quadrangle, Colorado

    Science.gov (United States)

    Cater, Fred W.; Bryner, Leonid

    1953-01-01

    The Davis Mesa quadrangle is one of eighteen 7 1/2-minute quadrangles covering the principal carnotite-producing area of southwestern Colorado. The geology of these quadrangles was mapped by the U.S. Geological Survey for the Atomic Energy Commission as part of a comprehensive study of carnotite deposits. The rocks exposed in the eighteen quadrangles consist of crystalline rocks of pre-Cambrian age and sedimentary rocks that range in age from late Paleozoic to Quaternary. Over much of the area the sedimentary rocks are flat lying, but in places the rocks are disrupted by hih-angle faults, and northwest-trending folds. Conspicuous among the folds are large anticlines having cores of intrusive salt and gypsum. Most of the carnotite deposits are confined to the Salt Wash sandstone member of Jurassic Morrison formation. Within this sandstone, most of the deposits are spottily distributed through an arcuate zone known as "Uruvan Mineral Belt". Individual deposits range in size from irregular masses containing only a few tons of ore to large, tabular masses containing many thousands of tons. The ore consists largely of sandstone selectively impregnated and in part replaced by uranium and vanadium minerals. Most of the deposits appear to be related to certain sedimentary structures in sandstones of favorable composition.

  9. Geology of the Anderson Mesa quadrangle, Colorado

    Science.gov (United States)

    Cater, Fred W.; Withington, C.F.

    1953-01-01

    The Anderson Mesa quadrangle is one of the eighteen 7 1/2-minute quadrangles covering the principal carnotite-producing area of the southwestern Colorado. The geology of these quadrangles was mapped by the U.S. Geological Survey for the Atomic Energy Commission as part of a comprehensive study of carnotite deposits. The rocks exposed in the eighteenth quadrangles consist of crystalline rocks of pre-Cambrian age and sedimentary rocks that range in age from late Paleozoic to Quarternary. Over much of the area the sedimentary rocks are flat lying, but in places the rocks are disrupted by high-angle faults, and northwest-tending folds. Conspicuous among the folds are large anticlines having cores of intrusive slat and gypsum. Most of the carnotite deposits are confined to the Salt Wash sandstone member of the Jurassic Morrison formation. Within this sandstone, most of the deposits are spottily distributed through an arcuate zone known as the "Uravan Mineral Belt". Individual deposits range in size from irregular masses containing many thousands of tons. The ore consists of largely of sandstone selectively impregnated and in part replaced by uranium and vanadium minerals. Most of the deposits appear to be related to certain sedimentary structures in sandstones of favorable composition.

  10. Geology of the Hamm Canyon quadrangle, Colorado

    Science.gov (United States)

    Cater, Fred W.

    1953-01-01

    The Hamm Canyon quadrangle is on eof eighteen 7 1/2-minute quadrangles covering the principal carnotite-producing area of southwestern Colorado. The geology of these quadrangles was mapped by the U.S. Geological Survey for the Atomic Energy Commission as part of a comprehensive study of carnotite deposits. The rocks exposed in the eighteen quadrangles consist of crystalline rocks of pre-Cambrian age and sedimentary rocks that range in age from late Paleozoic to Quaternary. Over much of the area the sedimentary rocks are flat lying, but in places the rocks are disrupted by high-angle faults, and northwest-trending folds. Conspicuous among the folds are large anticlines having cores of intrusive salt and gypsum. Most of the carnotite deposits are confined to the Salt Wash sandstone member of the Jurassic Morrison formation. Within this sandstone, most of the deposits are spottily distributed through an arcuate zone known as the "Uravan Mineral Belt". Individual deposits range in size from irregular masses containing only a few tons of ore to large, tabular masses containing many thousands of tons. The ore consists largely of sandstone selectively impregnated and in part replaced by uranium and vanadium minerals. Most of the deposits appear to be related to certain sedimentary structures in sandstones of favorable composition.

  11. Geology of the Naturita NW quadrangle, Colorado

    Science.gov (United States)

    Cater, Fred W.; Vogel, J.D.

    1953-01-01

    The Naturita NW quadrangle is one of eighteen 7 1/2-minute quadrangles covering the principal carnotite-producing area of southwestern Colorado. The geology of these quadrangles were mapped by the U.S. Geological Survey on behalf of the U.S. Atomic Energy Commission as part of a comprehensive study of carnotite deposits. The rocks exposed in the eighteen quadrangles consist of crystalline rocks of pre-Cambrian age and sedimentary rocks that range in age from late Paleozoic to Quaternary. Over much of the area the sedimentary rocks are flat lying, but in places the rocks are disrupted by high-angle faults, and northwest-trending folds. Conspicuous among the folds are large anticlines having cores of intrusive salt and gypsum. Most of the carnotite deposits are confined to the Salt Wash sandstone member of the Jurassic Morrison formation. Within this sandstone, most of the deposits are spottily distributed through an arcuate zone known as the "Uravan Mineral Belt". Individual deposits range in size from irregular masses containing only a few tons of ore to large, tabular masses containing many thousands of tons. The ore consists largely of sandstone selectively impregnated and in part replaced by uranium and vanadium minerals. Most of the deposits appear ro be related to certain sedimentary structures in sandstones of favorable composition.

  12. 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.

  13. 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)

  14. 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)

  15. Photosensitized synthesis of silver nanoparticles using Withania somnifera leaf powder and silver nitrate.

    Science.gov (United States)

    Raut, Rajesh Warluji; Mendhulkar, Vijay Damodhar; Kashid, Sahebrao Balaso

    2014-03-01

    The metal nanoparticle synthesis is highly explored field of nanotechnology. The biological methods seem to be more effective; however, due to slow reduction rate and polydispersity of the resulting products, they are less preferred. In the present study, we report rapid and facile synthesis of silver nanoparticles at room temperature. The exposure of reaction mixtures containing silver nitrate and dried leaf powder of Withania somnifera Linn to direct sunlight resulted in reduction of metal ions within five minutes whereas, the dark exposure took almost 12h. Further studies using different light filters reveal the role of blue light in reduction of silver ions. The synthesized silver nanoparticles were characterized by UV-Vis, Infrared spectroscopy (IR), Transmission Electron Microscopy (TEM), X-ray Diffraction studies (XRD), Nanoparticle Tracking Analysis (NTA), Energy Dispersive Spectroscopy (EDS), and Cyclic Voltammetry (CV). The Antibacterial and antifungal studies showed significant activity as compared to their respective standards.

  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. 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)

  18. 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...

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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)

  5. 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

  6. Drought characteristics' role in widespread aspen forest mortality across Colorado, USA.

    Science.gov (United States)

    Anderegg, Leander D L; Anderegg, William R L; Abatzoglou, John; Hausladen, Alexandra M; Berry, Joseph A

    2013-05-01

    Globally documented widespread drought-induced forest mortality has important ramifications for plant community structure, ecosystem function, and the ecosystem services provided by forests. Yet the characteristics of drought seasonality, severity, and duration that trigger mortality events have received little attention despite evidence of changing precipitation regimes, shifting snow melt timing, and increasing temperature stress. This study draws upon stand level ecohydrology and statewide climate and spatial analysis to examine the drought characteristics implicated in the recent widespread mortality of trembling aspen (Populus tremuloides Michx.). We used isotopic observations of aspen xylem sap to determine water source use during natural and experimental drought in a region that experienced high tree mortality. We then drew upon multiple sources of climate data to characterize the drought that triggered aspen mortality. Finally, regression analysis was used to examine the drought characteristics most associated with the spatial patterns of aspen mortality across Colorado. Isotopic analysis indicated that aspens generally utilize shallow soil moisture with little plasticity during drought stress. Climate analysis showed that the mortality-inciting drought was unprecedented in the observational record, especially in 2002 growing season temperature and evaporative deficit, resulting in record low shallow soil moisture reserves. High 2002 summer temperature and low shallow soil moisture were most associated with the spatial patterns of aspen mortality. These results suggest that the 2002 drought subjected Colorado aspens to the most extreme growing season water stress of the past century by creating high atmospheric moisture demand and depleting the shallow soil moisture upon which aspens rely. Our findings highlight the important role of drought characteristics in mediating widespread aspen forest mortality, link this aspen die-off to regional climate change

  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. Multiple surface plasmon polaritons modes on thin silver film controlled by a two-dimensional lattice of silver nanodimers

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Ying; Jiang, Yongyuan, E-mail: jiangyy@hit.edu.cn [Harbin Institute of Technology, Department of Physics (China)

    2015-01-15

    We study the optical resonant spectrum of a two-dimensional periodic array of silver nanodimers on a thin silver film using multiple scattering formalism. The excited multiple plasmonic modes on two interfaces of the silver film reveal that the dispersion relationships of surface plasmon polaritons on metallic film are modified by doubly periodic lattice due to the fact that wave vectors matching conditions are satisfied. Moreover, we demonstrate that the plasmonic modes are directly controlled by the thickness of silver film, as well as the gap between nanodimer array and silver film. These effects provide novel high-efficient and steady way for excitation in future plasmonic nanodevices.

  9. 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

  10. 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

  11. 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

  12. Silver oxide sorbent for carbon dioxide

    Science.gov (United States)

    Colombo, G. V.

    1974-01-01

    Material can be regenerated at least 20 times by heating at 250 C. Sorbent is compatible with environment of high humidity; up to 20% by weight of carbon dioxide can be absorbed. Material is prepared from silver carbonate, potassium hydroxide or carbonate, and sodium silicate.

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. Salinization of the Upper Colorado River - Fingerprinting Geologic Salt Sources

    Science.gov (United States)

    Tuttle, Michele L.W.; Grauch, Richard I.

    2009-01-01

    Salt in the upper Colorado River is of concern for a number of political and socioeconomic reasons. Salinity limits in the 1974 U.S. agreement with Mexico require the United States to deliver Colorado River water of a particular quality to the border. Irrigation of crops, protection of wildlife habitat, and treatment for municipal water along the course of the river also place restrictions on the river's salt content. Most of the salt in the upper Colorado River at Cisco, Utah, comes from interactions of water with rock formations, their derived soil, and alluvium. Half of the salt comes from the Mancos Shale and the Eagle Valley Evaporite. Anthropogenic activities in the river basin (for example, mining, farming, petroleum exploration, and urban development) can greatly accelerate the release of constituents from these geologic materials, thus increasing the salt load of nearby streams and rivers. Evaporative concentration further concentrates these salts in several watersheds where agricultural land is extensively irrigated. Sulfur and oxygen isotopes of sulfate show the greatest promise for fingerprinting the geologic sources of salts to the upper Colorado River and its major tributaries and estimating the relative contribution from each geologic formation. Knowing the salt source, its contribution, and whether the salt is released during natural weathering or during anthropogenic activities, such as irrigation and urban development, will facilitate efforts to lower the salt content of the upper Colorado River.

  18. Good Days on the Trail, 1938-1942: Film Footage of the Rocky Mountains, Colorado

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This film documents student hiking trips conducted by the University of Colorado at Boulder in the Rocky Mountains, Colorado, USA during the summers of 1938-1942....

  19. Silver nanoparticle toxicity in Drosophila: size does matter

    Directory of Open Access Journals (Sweden)

    Deborah J Gorth

    2011-02-01

    Full Text Available Deborah J Gorth1, David M Rand2, Thomas J Webster11School of Engineering, 2Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, USABackground: Consumer nanotechnology is a growing industry. Silver nanoparticles are the most common nanomaterial added to commercially available products, so understanding the influence that size has on toxicity is integral to the safe use of these new products. This study examined the influence of silver particle size on Drosophila egg development by comparing the toxicity of both nanoscale and conventional-sized silver particles.Methods: The toxicity assays were conducted by exposing Drosophila eggs to particle concentrations ranging from 10 ppm to 100 ppm of silver. Size, chemistry, and agglomeration of the silver particles were evaluated using transmission electron microscopy, X-ray photoelectron spectroscopy, and dynamic light scattering.Results: This analysis confirmed individual silver particle sizes in the ranges of 20–30 nm, 100 nm, and 500–1200 nm, with similar chemistry. Dynamic light scattering and transmission electron microscope data also indicated agglomeration in water, with the transmission electron microscopic images showing individual particles in the correct size range, but the dynamic light scattering z-average sizes of the silver nanoparticles were 782 ± 379 nm for the 20–30 nm silver nanoparticles, 693 ± 114 nm for the 100 nm silver nanoparticles, and 508 ± 32 nm for the 500–1200 nm silver particles. Most importantly, here we show significantly more Drosophila egg toxicity when exposed to larger, nonnanometer silver particles. Upon exposure to silver nanoparticles sized 20–30 nm, Drosophila eggs did not exhibit a statistically significant (P < 0.05 decrease in their likelihood to pupate, but eggs exposed to larger silver particles (500–1200 nm were 91% ± 18% less likely to pupate. Exposure to silver nanoparticles reduced the percentage of pupae able

  20. 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...

  1. 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...

  2. 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.

  3. 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

  4. 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...

  5. 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...

  6. 76 FR 43715 - Notice of Inventory Completion: University of Colorado Museum, Boulder, CO

    Science.gov (United States)

    2011-07-21

    ... 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... University of Colorado Museum. ] Repatriation of the human remains and associated funerary objects to...

  7. 76 FR 43713 - Notice of Inventory Completion: University of Colorado Museum, Boulder, CO

    Science.gov (United States)

    2011-07-21

    ... 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...

  8. 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...

  9. 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…

  10. 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

  11. 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…

  12. Is the Profile of the Colorado River in the Colorado Plateau in Equilibrium With Bedrock?

    Science.gov (United States)

    Mackley, R. D.; Pederson, J. L.

    2003-12-01

    The Colorado River sets the pace for the erosion of the Colorado Plateau and part of the Rocky Mountains, and the evolution of its long-profile may hold the key to resolving debate over the region's late Cenozoic erosional and tectonic history. Significant reach (10 km) and canyon-scale (100 km) gradient variations occur along the modern profile of this mixed bedrock-alluvial river, and there are multiple hypotheses for the controls on its gradient: 1) knickzones related to active tectonics in western Grand Canyon, 2) coarse bed material from tributary side-canyons, and 3) bedrock resistance as a direct control with respect to channel substrate or an indirect control in terms of hillslope processes in tributary catchments and the production and comminution of bed material. The goal of this study is to test for a spatial relation between hydraulic driving forces and bedrock resisting forces at reach and canyon-scales within and between Glen and Grand canyons. The river encounters diverse rock types that vary in hardness and fracture density. Field and GIS results aimed at testing the bedrock resistance hypothesis for Glen and Grand canyons indicate a spatial relation between rock-mass strength (RMS) and channel gradient. Reach-scale gradients vary as much as a factor of 20 through Grand Canyon, with steep reaches having significantly higher compressive strengths and wide fracture spacings. Glen Canyon, on the other hand, has dramatically lower channel gradient, weaker RMS properties, and reaches with steep gradients that do not correlate to either debris fans or changes in bedrock type but do coincide with geologic structures. The presence of a bedrock or debris-fan frequency correlation to the majority of gradient variations argues against tectonic origins of knickzones and suggests a relation between bedrock resistance and the profile of the Colorado River exists. However, when these results are combined with the distribution of tributary debris fans and their

  13. The Colorado Plateau II: biophysical, socioeconomic, and cultural research

    Science.gov (United States)

    Mattson, David J.; van Riper, Charles

    2005-01-01

    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 focusing on the integration of science into resource management issues. The 32 chapters range in content from measuring human impacts on cultural resources, through grazing and the wildland-urban interface issues, to parameters of climate change on the Plateau. The book also introduces economic perspectives by considering shifting patterns and regional disparities in the Colorado Plateau economy. A series of chapters on mountain lions explores the human-wildland interface. These chapters deal with the entire spectrum of challenges associated with managing this large mammal species in Arizona and on the Colorado Plateau, conveying a wealth of timely information of interest to wildlife managers and enthusiasts. Another provocative set of chapters on biophysical resources explores the management of forest restoration, from the micro scale all the way up to large-scale GIS analyses of ponderosa pine ecosystems on the Colorado Plateau. Given recent concerns for forest health in the wake of fires, severe drought, and bark-beetle infestation, these chapters will prove enlightening for forest service, park service, and land management professionals at both the federal and state level, as well as general readers interested in how forest management practices will ultimately affect their recreation activities. With broad coverage that touches on topics as diverse as movement patterns of rattlesnakes, calculating watersheds, and rescuing looted rockshelters, this volume stands as a compendium of cutting-edge research on the Colorado Plateau that offers a wealth of insights for many scholars.

  14. 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

  15. Evolution of the Creede Caldera and its relation to mineralization in the Creede mining district, Colorado

    Science.gov (United States)

    Barton, Paul B.; Rye, Robert O.; Bethke, Philip M.

    2000-01-01

    At 25 Ma a major epithermal silver and base metal deposit formed in rhyolitic welded tuff near Creede, Colorado. Nearly 24000 metric tons of silver, appreciable lead, and small amounts of zinc, copper, and gold, have been produced from large, crustified veins under Bachelor and Bulldog Mountains north and northwest of Creede. Prior geologic, hydrologic, and stable-isotope studies showed that ore deposition was associated with the mixing and boiling of waters from diverse sources and suggester that a critical part of the ore-forming fluid may have originated within the ancient lake and sediments of the lacustrine Creede Formation that filled the Creede caldera. Two drill holes that sampled the heretofore hidden lower half of the Creede Formation are the focus of this book. The Creede caldera formed at 26.9 Ma within a high constructional plateau of silicic ashflows that covered and were sporadically interlayed with, intermediate lavas and lahars from large stratovolcanoes. The Creede caldera lake had an inflow evaporation balance that did not permit rapid filling to create a brim-full deep lake. Thus salts were evaporatively concentrated; but, with the exception of possible gypsum, no evaporite minerals preserved. Cool springs deposited travertine as mounds and contributed to limestone interlaminations within the sediment. The lake bottom was anoxic, and bacterial reduction of sulfate led to extreme sulfur isotopic fractionation in diagenetic pyrite. The caldera gradually resurged, converting the initial equant lake into an arcuate moat. Resurgent doming, alluvial fans, lacustrine sediments, ashfalls, and lava domes displaced water, lifted the lake so that it overlapped what later became the southern edge of the mineralized are, and eventually filled the basin. At 25.1 Ma an unseen pluton intruded beneath the northen part of the Creede district and created a convecting olume that drew in brine from the Creede caldera fill, meteotic water from highlands to the north

  16. 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.

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

    Science.gov (United States)

    Bilberg, Katrine; Hovgaard, Mads Bruun; Besenbacher, Flemming; Baatrup, Erik

    2012-01-01

    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 (AgNO(3)). The nanosilver and silver ion 48-hour median lethal concentration (LC(50)) 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.

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

    Science.gov (United States)

    Bilberg, Katrine; Hovgaard, Mads Bruun; Besenbacher, Flemming; Baatrup, Erik

    2012-01-01

    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. PMID:22174711

  19. 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.

  20. 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.

  1. 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.

  2. 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...

  3. Increased DNA damage and oxidative stress among silver jewelry workers.

    Science.gov (United States)

    Aktepe, Necmettin; Kocyigit, Abdurrahim; Yukselten, Yunus; Taskin, Abdullah; Keskin, Cumali; Celik, Hakim

    2015-04-01

    Silver has long been valued as a precious metal, and it is used to make ornaments, jewelry, high-value tableware, utensils, and currency coins. Human exposures to silver and silver compounds can occur oral, dermal, or by inhalation. In this study, we investigated genotoxic and oxidative effects of silver exposure among silver jewelry workers. DNA damage in peripheral mononuclear leukocytes was measured by using the comet assay. Serum total antioxidative status (TAS), total oxidative status (TOS), total thiol contents, and ceruloplasmin levels were measured by using colorimetric methods among silver jewelry workers. Moreover, oxidative stress index (OSI) was calculated. Results were compared with non-exposed healthy subjects. The mean values of mononuclear leukocyte DNA damage were significantly higher than control subjects (p jewelry workers caused oxidative stress and accumulation of severe DNA damage.

  4. 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......, 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...... 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...

  5. 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.

  6. 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...

  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. 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

  9. SILVER NANOPARTICLES AS PENICILLIN ACTION ENHANCERS

    Directory of Open Access Journals (Sweden)

    O. A. Vasylchenko

    2013-04-01

    Full Text Available Nowadays, the value of bactericidal nanomaterials research increases at the increasing number of bacteria strains resistant to the most highly potent antibiotics. In the review the characteristic of nanoparticles and methods for their production are done. The scope of nanoparticles application is observed, special attention is focused on silver nanoparticles usage in medicine, in particular, as bactericidal products. It is indicated that nanoparticles may have toxic effects. Much attention is paid to nanoparticles application in the treatment of various diseases, for example, for targeted drug delivery, wound healing, bone regeneration, local heating of tumors in cancer pathology, immune system stimulation, for antibodies, viruses, bacteria detection, for liquids filtration. Penicillins and their producers — Penicillium sp. characteristic is done. The mechanism of penicillin antimicrobial action is estimated. It is revealed that silver nanoparticles usage in combination with antibiotics, particularly penicillin, leads to antibiotics antibacterial activity increasing against gram-positive and gram-negative microorganisms.

  10. 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...

  11. 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)

  12. 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.

  13. 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.

  14. 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...

  15. 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.

  16. Heterolysis of Dihydrogen by Silver Alkoxides and Fluorides.

    Science.gov (United States)

    Tate, Brandon K; Nguyen, Jenna T; Bacsa, John; Sadighi, Joseph P

    2015-07-01

    Alkoxide-bridged disilver cations react with dihydrogen to form hydride-bridged cations, releasing free alcohol. Hydrogenolysis of neutral silver fluorides affords hydride-bridged disilver cations as their bifluoride salts. These reactions proceed most efficiently when the supporting ligands are expanded N-heterocyclic carbenes (NHCs) derived from 6- and 7-membered cyclic amidinium salts. Kinetics studies show that silver fluoride hydrogenolysis is first-order in both silver and dihydrogen.

  17. 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.

  18. 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 ...

  19. 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...

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

    Science.gov (United States)

    Manea, Florica; Motoc, Sorina; Pop, Aniela; Remes, Adriana; Schoonman, Joop

    2012-06-01

    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.

  1. 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...

  2. Silver- and gold-mediated nucleobase bonding.

    Science.gov (United States)

    Acioli, Paulo H; Srinivas, Sudha

    2014-08-01

    We report the results of a density functional theory investigation of the bonding of nucleobases mediated by silver and gold atoms in the gas phase. Our calculations use the Becke exchange and Perdew-Wang correlation functional (BPW91) combined with the Stuttgart effective core potentials to represent the valence electrons of gold, silver, and platinum, and the all-electron DGTZVP basis set for C, H, N, and O. This combination was chosen based on tests on the metal atoms and tautomers of adenine, cytosine, and guanine. To establish a benchmark to understand the metal-mediated bonding, we calculated the binding energy of each of the base pairs in their canonical forms. Our calculations show rather strong bonds between the Watson-Crick base pairs when compared with typical values for N-H-N and N-H-O hydrogen bonds. The neutral metal atoms tend to bond near the nitrogen atoms. The effect of the metal atoms on the bonding of nucleobases differs depending on whether or not the metal atoms bond to one of the hydrogen-bonding sites. When the silver or gold atoms bond to a non-hydrogen-bonding site, the effect is a slight enhancement of the cytosine-guanine bonding, but there is almost no effect on the adenine-thymine pairing. The metal atoms can block one of the hydrogen-bonding sites, thus preventing the normal cytosine-guanine and adenine-thymine pairings. We also find that both silver and gold can bond to consecutive guanines in a similar fashion to platinum, albeit with a significantly lower binding energy.

  3. 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...

  4. 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...

  5. Alternative Plasmonic Materials: Beyond Gold and Silver

    DEFF Research Database (Denmark)

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

    2013-01-01

    in plasmonics and metamaterials lacks good material building blocks in order to realize useful devices. Such devices suffer from many drawbacks arising from the undesirable properties of their material building blocks, especially metals. There are many materials, other than conventional metallic components...... such as gold and silver, that exhibit metallic properties and provide advantages in device performance, design flexibility, fabrication, integration, and tunability. This review explores different material classes for plasmonic and metamaterial applications, such as conventional semiconductors, transparent...

  6. 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

  7. 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)

  8. Evaluation of Colorado Learning Attitudes about Science Survey

    Science.gov (United States)

    Douglas, K. A.; Yale, M. S.; Bennett, D. E.; Haugan, M. P.; Bryan, L. A.

    2014-01-01

    The Colorado Learning Attitudes about Science Survey (CLASS) is a widely used instrument designed to measure student attitudes toward physics and learning physics. Previous research revealed a fairly complex factor structure. In this study, exploratory and confirmatory factor analyses were conducted on data from an undergraduate introductory…

  9. 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…

  10. 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.

  11. 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.

  12. 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...

  13. 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...

  14. 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…

  15. 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)…

  16. 78 FR 60008 - Colorado Disaster Number CO-00065

    Science.gov (United States)

    2013-09-30

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS 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...

  17. An Evaluation of Colorado's College Opportunity Fund and Related Policies

    Science.gov (United States)

    Western Interstate Commission for Higher Education, 2009

    2009-01-01

    During the spring of 2004, the State of Colorado enacted legislation that fundamentally changed the mechanisms through which it financed its public higher education system, beginning with the 2005-06 academic year. Rather than appropriating funds directly to institutions, the legislation created the College Opportunity Fund (COF), the principal…

  18. The Social Work Research Center at Colorado State University

    Science.gov (United States)

    Winokur, Marc A.; Valentine, Deborah P.; Drendel, James M.

    2009-01-01

    The Social Work Research Center is an innovative university-community partnership within the School of Social Work in the College of Applied Human Sciences at Colorado State University. The center is focused on working with county and state child welfare agencies to generate applied research that translates into evidence-based practice for serving…

  19. 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,...

  20. 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.

  1. 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…

  2. Transgenic resistance of eggplants to the Colorado potato beetle

    NARCIS (Netherlands)

    Arpaia, S.

    1999-01-01

    The subject of this thesis is the use of transgenic plant resistance as a method to control the Colorado potato beetle, Leptinotarsa decemlineata Say in eggplant. The gene conferring resistance is coding for a Cry3B toxin and it is a synthetic version of a wild-type gene originally obtained from the

  3. Building Blocks to Colorado's Content Standards: Mathematics, Reading and Writing.

    Science.gov (United States)

    Allen-Young, Darcy; Amundson, Jane L.; Bowers, Lori Goodwin; Koehn, Jo; Triolo-Moloney, Sharon; Vendegna, Nan; Peterson, Sandra

    The Building Blocks to Colorado's Content Standards were developed to connect early childhood education to the K-12 content standards, to advocate for appropriate teaching strategies for preschool children, and to support awareness and understanding of early childhood foundational skills among parents and teachers. Five sets of building blocks are…

  4. 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. ...

  5. 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.

  6. 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.

  7. 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.

  8. Toxicity of silver nanoparticles in zebrafish models

    Energy Technology Data Exchange (ETDEWEB)

    Asharani, P V; Valiyaveettil, Suresh [Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, 117543 (Singapore); Wu Yilian; Gong Zhiyuan [Department of Biological Sciences, National University of Singapore, Science Drive 4, 117543 (Singapore)], E-mail: chmsv@nus.edu.sg

    2008-06-25

    This study was initiated to enhance our insight on the health and environmental impact of silver nanoparticles (Ag-np). Using starch and bovine serum albumin (BSA) as capping agents, silver nanoparticles were synthesized to study their deleterious effects and distribution pattern in zebrafish embryos (Danio rerio). Toxicological endpoints like mortality, hatching, pericardial edema and heart rate were recorded. A concentration-dependent increase in mortality and hatching delay was observed in Ag-np treated embryos. Additionally, nanoparticle treatments resulted in concentration-dependent toxicity, typified by phenotypes that had abnormal body axes, twisted notochord, slow blood flow, pericardial edema and cardiac arrhythmia. Ag{sup +} ions and stabilizing agents showed no significant defects in developing embryos. Transmission electron microscopy (TEM) of the embryos demonstrated that nanoparticles were distributed in the brain, heart, yolk and blood of embryos as evident from the electron-dispersive x-ray analysis (EDS). Furthermore, the acridine orange staining showed an increased apoptosis in Ag-np treated embryos. These results suggest that silver nanoparticles induce a dose-dependent toxicity in embryos, which hinders normal development.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Synovial fluid over the centuries

    Directory of Open Access Journals (Sweden)

    P. Marson

    2011-09-01

    Full Text Available This review deals with the most meaningful historical topics on the study of synovial fluid, by starting from the Greco- Roman Medicine, up to Paracelsus (1493-1541, who introduced the term “synovia” to name the intra-articular humour. Afterwards, some till now unreported historical sources are recorded, e.g., a short text by the Italian XVIII century physician Giambattista Contoli (“Breve Instruzione sopre il Glutine, ò Colla…, 1699”. Then, in keeping with some recent researches, a brief history of arthrocentesis is outlined, by considering the first procedures, which should have been performed in Mexico, during the precolonial period. Moreover, the first chemical analysis of synovial fluid, as carried out by the French chemist Jean-Louis Margueron (1792, and the first modern study on the synovial membrane by Marie-François-Xavier Bichat (1800 are explained. Finally, some XIX century investigations concerning the synovial pharmacodynamics, in particular an Italian one based on the elimination of certain chemical substances through the synovial membrane, are discussed.

  17. Climate change impacts on streamflow and subbasin-scale hydrology in the Upper Colorado River Basin.

    Science.gov (United States)

    Ficklin, Darren L; Stewart, Iris T; Maurer, Edwin P

    2013-01-01

    In the Upper Colorado River Basin (UCRB), the principal source of water in the southwestern U.S., demand exceeds supply in most years, and will likely continue to rise. While General Circulation Models (GCMs) project surface temperature warming by 3.5 to 5.6°C for the area, precipitation projections are variable, with no wetter or drier consensus. We assess the impacts of projected 21(st) century climatic changes on subbasins in the UCRB using the Soil and Water Assessment Tool, for all hydrologic components (snowmelt, evapotranspiration, surface runoff, subsurface runoff, and streamflow), and for 16 GCMs under the A2 emission scenario. Over the GCM ensemble, our simulations project median Spring streamflow declines of 36% by the end of the 21(st) century, with increases more likely at higher elevations, and an overall range of -100 to +68%. Additionally, our results indicated Summer streamflow declines with median decreases of 46%, and an overall range of -100 to +22%. Analysis of hydrologic components indicates large spatial and temporal changes throughout the UCRB, with large snowmelt declines and temporal shifts in most hydrologic components. Warmer temperatures increase average annual evapotranspiration by ∼23%, with shifting seasonal soil moisture availability driving these increases in late Winter and early Spring. For the high-elevation water-generating regions, modest precipitation decreases result in an even greater water yield decrease with less available snowmelt. Precipitation increases with modest warming do not translate into the same magnitude of water-yield increases due to slight decreases in snowmelt and increases in evapotranspiration. For these basins, whether modest warming is associated with precipitation decreases or increases, continued rising temperatures may make drier futures. Subsequently, many subbasins are projected to turn from semi-arid to arid conditions by the 2080 s. In conclusion, water availability in the UCRB could

  18. Separation of silver ions and starch modified silver nanoparticles using high performance liquid chromatography with ultraviolet and inductively coupled mass spectrometric detection

    Energy Technology Data Exchange (ETDEWEB)

    Hanley, Traci A.; Saadawi, Ryan; Zhang, Peng; Caruso, Joseph A., E-mail: joseph.caruso@uc.edu; 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{sup +}) 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{sup −1} detection limit, and 90% chromatographic recovery for silver solutions containing ions and starch stabilized silver nanoparticles smaller than 100 nm.

  19. Speciation Matters: Bioavailability of Silver and Silver Sulfide Nanoparticles to Alfalfa (Medicago sativa).

    Science.gov (United States)

    Stegemeier, John P; Schwab, Fabienne; Colman, Benjamin P; Webb, Samuel M; Newville, Matthew; Lanzirotti, Antonio; Winkler, Christopher; Wiesner, Mark R; Lowry, Gregory V

    2015-07-21

    Terrestrial crops are directly exposed to silver nanoparticles (Ag-NPs) and their environmentally transformed analog silver sulfide nanoparticles (Ag2S-NPs) when wastewater treatment biosolids are applied as fertilizer to agricultural soils. This leads to a need to understand their bioavailability to plants. In the present study, the mechanisms of uptake and distribution of silver in alfalfa (Medicago sativa) were quantified and visualized upon hydroponic exposure to Ag-NPs, Ag2S-NPs, and AgNO3 at 3 mg total Ag/L. Total silver uptake was measured in dried roots and shoots, and the spatial distribution of elements was investigated using transmission electron microscopy (TEM) and synchrotron-based X-ray imaging techniques. Despite large differences in release of Ag(+) ions from the particles, Ag-NPs, Ag2S-NPs, and Ag(+) became associated with plant roots to a similar degree, and exhibited similarly limited (XRF) mapping revealed differences in the distribution of Ag into roots for each treatment. Silver nanoparticles mainly accumulated in the (columella) border cells and elongation zone, whereas Ag(+) accumulated more uniformly throughout the root. In contrast, Ag2S-NPs remained largely adhered to the root exterior, and the presence of cytoplasmic nano-SixOy aggregates was observed. Exclusively in roots exposed to particulate silver, NPs smaller than the originally dosed NPs were identified by TEM in the cell walls. The apparent accumulation of Ag in the root apoplast determined by XRF, and the presence of small NPs in root cell walls suggests uptake of partially dissolved NPs and translocation along the apoplast. PMID:26106801

  20. Speciation Matters: Bioavailability of Silver and Silver Sulfide Nanoparticles to Alfalfa (Medicago sativa).

    Science.gov (United States)

    Stegemeier, John P; Schwab, Fabienne; Colman, Benjamin P; Webb, Samuel M; Newville, Matthew; Lanzirotti, Antonio; Winkler, Christopher; Wiesner, Mark R; Lowry, Gregory V

    2015-07-21

    Terrestrial crops are directly exposed to silver nanoparticles (Ag-NPs) and their environmentally transformed analog silver sulfide nanoparticles (Ag2S-NPs) when wastewater treatment biosolids are applied as fertilizer to agricultural soils. This leads to a need to understand their bioavailability to plants. In the present study, the mechanisms of uptake and distribution of silver in alfalfa (Medicago sativa) were quantified and visualized upon hydroponic exposure to Ag-NPs, Ag2S-NPs, and AgNO3 at 3 mg total Ag/L. Total silver uptake was measured in dried roots and shoots, and the spatial distribution of elements was investigated using transmission electron microscopy (TEM) and synchrotron-based X-ray imaging techniques. Despite large differences in release of Ag(+) ions from the particles, Ag-NPs, Ag2S-NPs, and Ag(+) became associated with plant roots to a similar degree, and exhibited similarly limited (roots for each treatment. Silver nanoparticles mainly accumulated in the (columella) border cells and elongation zone, whereas Ag(+) accumulated more uniformly throughout the root. In contrast, Ag2S-NPs remained largely adhered to the root exterior, and the presence of cytoplasmic nano-SixOy aggregates was observed. Exclusively in roots exposed to particulate silver, NPs smaller than the originally dosed NPs were identified by TEM in the cell walls. The apparent accumulation of Ag in the root apoplast determined by XRF, and the presence of small NPs in root cell walls suggests uptake of partially dissolved NPs and translocation along the apoplast.

  1. 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.

  2. 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.

  3. 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...

  4. 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.

  5. 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...

  6. 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

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

    OpenAIRE

    Bilberg, Katrine; Hovgaard, Mads Bruun; Besenbacher, Flemming; Baatrup, Erik

    2011-01-01

    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 ...

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

    OpenAIRE

    Katrine Bilberg; Mads Bruun Hovgaard; Flemming Besenbacher; Erik Baatrup

    2012-01-01

    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 ...

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. Nearshore thermal gradients of the Colorado River near the Little Colorado River confluence, Grand Canyon National Park, Arizona, 2010

    Science.gov (United States)

    Ross, Rob; Grams, Paul E.

    2013-01-01

    Construction and operation of Glen Canyon Dam has dramatically impacted the flow of the Colorado River through Glen, Marble, and Grand Canyons. Extremes in both streamflow and water temperature have been suppressed by controlled releases from the dam. Trapping of sediment in Lake Powell, the reservoir formed by Glen Canyon Dam, has also dramatically reduced the supply of suspended sediment entering the system. These changes have altered the riverine ecosystem and the habitat of native species, including fish such as the endangered humpback chub (Gila cypha). Most native fish are adapted to seasonally warm water, and the continuous relatively cold water released by the dam is one of the factors that is believed to limit humpback chub growth and survival. While average mainstem temperatures in the Colorado River are well documented, there is limited understanding of temperatures in the nearshore environments that fish typically occupy. Four nearshore geomorphic unit types were studied between the confluence of the Colorado and Little Colorado Rivers and Lava Canyon in the summer and fall of 2010, for study periods of 10 to 27 days. Five to seven sites were studied during each interval. Persistent thermal gradients greater than the 0.2 °C accuracy of the instruments were not observed in any of the sampled shoreline environments. Temperature gradients between the shoreline and mainstem on the order of 4 °C, believed to be important to the habitat-seeking behavior of native or nonnative fishes, were not detected.

  14. Mechanical, electrical, and thermal expansion properties of carbon nanotube-based silver and silver-palladium alloy composites

    Institute of Scientific and Technical Information of China (English)

    Hemant Pal; Vimal Sharma

    2014-01-01

    The mechanical, electrical, and thermal expansion properties of carbon nanotube (CNT)-based silver and silver–palladium (10:1, w/w) alloy nanocomposites are reported. To tailor the properties of silver, CNTs were incorporated into a silver matrix by a modified mo-lecular level-mixing process. CNTs interact weakly with silver because of their non-reactive nature and lack of mutual solubility. Therefore, palladium was utilized as an alloying element to improve interfacial adhesion. Comparative microstructural characterizations and property evaluations of the nanocomposites were performed. The structural characterizations revealed that decorated type-CNTs were dispersed, em-bedded, and anchored into the silver matrix. The experimental results indicated that the modification of the silver and silver–palladium nanocomposite with CNT resulted in increases in the hardness and Young’s modulus along with concomitant decreases in the electrical con-ductivity and the coefficient of thermal expansion (CTE). The hardness and Young’s modulus of the nanocomposites were increased by 30%-40% whereas the CTE was decreased to 50%-60% of the CTE of silver. The significantly improved CTE and the mechanical proper-ties of the CNT-reinforced silver and silver–palladium nanocomposites are correlated with the intriguing properties of CNTs and with good interfacial adhesion between the CNTs and silver as a result of the fabrication process and the contact action of palladium as an alloying ele-ment.

  15. 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

  16. 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.

  17. 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)

  18. 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.

  19. Capillary electrophoresis coupled with inductively coupled mass spectrometry as an alternative to cloud point extraction based methods for rapid quantification of silver ions and surface coated silver nanoparticles.

    Science.gov (United States)

    Qu, Haiou; Mudalige, Thilak K; Linder, Sean W

    2016-01-15

    Speciation and accurate quantification of ionic silver and metallic silver nanoparticles are critical to investigate silver toxicity and to determine the shelf-life of products that contain nano silver under various storage conditions. We developed a rapid method for quantification of silver ions and silver nanoparticles using capillary electrophoresis (CE) interfaced with inductively-coupled plasma mass spectrometry (ICPMS). The addition of 2-mercaptopropionylglycine (tiopronin) to the background electrolyte was used to facilitate the chromatographic separation of ionic silver and maintain the oxidation state of silver. The obtained limits of detection were 0.05 μg kg(-1) of silver nanoparticles and 0.03 μg kg(-1) of ionic silver. Nanoparticles of varied sizes (10-110 nm) with different surface coating, including citrate acid, lipoic acid, polyvinylpyrrolidone and bovine serum albumin (BSA) were successfully analyzed. Particularly good recoveries (>93%) were obtained for both ionic silver and silver nanoparticle in the presence of excess amount of BSA. The method was further tested with six commercially available dietary supplements which varied in concentration and matrix components. The summed values of silver ions and silver nanoparticles correlated well with the total silver concentration determined by ICPMS after acid digestion. This method can serve as an alternative to cloud point extraction technique when the extraction efficiency for protein coated nanoparticles is low.

  20. Capillary electrophoresis coupled with inductively coupled mass spectrometry as an alternative to cloud point extraction based methods for rapid quantification of silver ions and surface coated silver nanoparticles.

    Science.gov (United States)

    Qu, Haiou; Mudalige, Thilak K; Linder, Sean W

    2016-01-15

    Speciation and accurate quantification of ionic silver and metallic silver nanoparticles are critical to investigate silver toxicity and to determine the shelf-life of products that contain nano silver under various storage conditions. We developed a rapid method for quantification of silver ions and silver nanoparticles using capillary electrophoresis (CE) interfaced with inductively-coupled plasma mass spectrometry (ICPMS). The addition of 2-mercaptopropionylglycine (tiopronin) to the background electrolyte was used to facilitate the chromatographic separation of ionic silver and maintain the oxidation state of silver. The obtained limits of detection were 0.05 μg kg(-1) of silver nanoparticles and 0.03 μg kg(-1) of ionic silver. Nanoparticles of varied sizes (10-110 nm) with different surface coating, including citrate acid, lipoic acid, polyvinylpyrrolidone and bovine serum albumin (BSA) were successfully analyzed. Particularly good recoveries (>93%) were obtained for both ionic silver and silver nanoparticle in the presence of excess amount of BSA. The method was further tested with six commercially available dietary supplements which varied in concentration and matrix components. The summed values of silver ions and silver nanoparticles correlated well with the total silver concentration determined by ICPMS after acid digestion. This method can serve as an alternative to cloud point extraction technique when the extraction efficiency for protein coated nanoparticles is low. PMID:26724893

  1. Geology of Precambrian rocks and isotope geochemistry of shear zones in the Big Narrows area, northern Front Range, Colorado

    Science.gov (United States)

    Abbott, Jeffrey T.

    1970-01-01

    Rocks within the Big Narrows and Poudre Park quadrangles located in the northern Front Range of Colorado are Precambrian metasedimentary and metaigneous schists and gneisses and plutonic igneous rocks. These are locally mantled by extensive late Tertiary and Quaternary fluvial gravels. The southern boundary of the Log Cabin batholith lies within the area studied. A detailed chronology of polyphase deformation, metamorphism and plutonism has been established. Early isoclinal folding (F1) was followed by a major period of plastic deformation (F2), sillimanite-microcline grade regional metamorphism, migmatization and synkinematic Boulder Creek granodiorite plutonism (1.7 b.y.). Macroscopic doubly plunging antiformal and synformal structures were developed. P-T conditions at the peak of metamorphism were probably about 670?C and 4.5 Kb. Water pressures may locally have differed from load pressures. The 1.4 b.y. Silver Plume granite plutonism was post kinematic and on the basis of petrographic and field criteria can be divided into three facies. Emplacement was by forcible injection and assimilation. Microscopic and mesoscopic folds which postdate the formation of the characteristic mineral phases during the 1.7 b.y. metamorphism are correlated with the emplacement of the Silver Plume Log Cabin batholith. Extensive retrograde metamorphism was associated with this event. A major period of mylonitization postdates Silver Plume plutonism and produced large E-W and NE trending shear zones. A detailed study of the Rb/Sr isotope geochemistry of the layered mylonites demonstrated that the mylonitization and associated re- crystallization homogenized the Rb87/Sr 86 ratios. Whole-rock dating techniques applied to the layered mylonites indicate a probable age of 1.2 b.y. Petrographic studies suggest that the mylonitization-recrystallization process produced hornfels facies assemblages in the adjacent metasediments. Minor Laramide faulting, mineralization and igneous activity

  2. 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

  3. 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.

  4. 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.

    2016-02-10

    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.

  5. Computational probes into the basis of silver ion chromatography. II. Silver(I)-olefin complexes

    NARCIS (Netherlands)

    Kaneti, J.; Smet, de L.C.P.M.; Boom, R.M.; Zuilhof, H.; Sudhölter, E.J.R.

    2002-01-01

    Alkene complexes of silver(I) are studied by four computational methodologies: ab initio RHF, MP2, and MP4 computations, and density functional B3LYP computations, with a variety of all-electron and effective core potential basis sets. Methodological studies indicate that MP2/SBK(d) computations can

  6. Otvetshajet Silver Vohu, starshii spetsialist bjuro po svjazam s obshtshestvennostju Eesti Pank / Silver Vohu

    Index Scriptorium Estoniae

    Vohu, Silver, 1980-

    2006-01-01

    17. juulil 2006 korrigeeris reitinguagentuur Standard & Poor's Eesti Vabariigi reitingu väljavaadet, muutes selle võimaliku euroalaga liitumise edasilükkumise tõttu positiivsest stabiilseks. Küsimustele vastab Eesti Panga avalike suhete büroo juhtivspetsialist Silver Vohu

  7. The Effect of Silver Chloride Formation on the Kinetics of Silver Dissolution in Chloride Solution

    Science.gov (United States)

    Ha, Hung; Payer, Joe

    2011-01-01

    The precipitation and growth of AgCl on silver in physiological NaCl solution were investigated. AgCl was found to form at bottom of scratches on the surface which may be the less effective sites for diffusion or the favorable sites for heterogeneous nucleation. Patches of silver chloride expanded laterally on the substrate until a continuous film formed. The ionic transport path through this newly formed continuous film was via spaces between AgCl patches. As the film grew, the spaces between AgCl patches closed and ion transport was primarily via micro-channels running through AgCl patches. The decrease of AgCl layer conductivity during film growth were attributed to the clogging of micro-channels or decrease in charge carrier concentration inside the micro-channels. Under thin AgCl layer, i.e. on the order of a micrometer, the dissolution of silver substrate was under mixed activation-Ohmic control. Under thick AgCl layer, i.e. on the order of tens of micrometers, the dissolution of silver substrate was mediated by the Ohmic resistance of AgCl layer. PMID:21516171

  8. The Effect of Silver Chloride Formation on the Kinetics of Silver Dissolution in Chloride Solution.

    Science.gov (United States)

    Ha, Hung; Payer, Joe

    2011-02-28

    The precipitation and growth of AgCl on silver in physiological NaCl solution were investigated. AgCl was found to form at bottom of scratches on the surface which may be the less effective sites for diffusion or the favorable sites for heterogeneous nucleation. Patches of silver chloride expanded laterally on the substrate until a continuous film formed. The ionic transport path through this newly formed continuous film was via spaces between AgCl patches. As the film grew, the spaces between AgCl patches closed and ion transport was primarily via micro-channels running through AgCl patches. The decrease of AgCl layer conductivity during film growth were attributed to the clogging of micro-channels or decrease in charge carrier concentration inside the micro-channels. Under thin AgCl layer, i.e. on the order of a micrometer, the dissolution of silver substrate was under mixed activation-Ohmic control. Under thick AgCl layer, i.e. on the order of tens of micrometers, the dissolution of silver substrate was mediated by the Ohmic resistance of AgCl layer.

  9. 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

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

    DEFF Research Database (Denmark)

    Miclaus, Teodora

    2015-01-01

    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 compound. Increased...

  11. Laser ablation deposition measurements from silver and nickel

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Ellegaard, Ole; Schou, Jørgen

    1996-01-01

    The deposition rate for laser ablated metals has been studied in a standard geometry for fluences up to 20 J/cm(2). The rate for silver and nickel is a few percent of a monolayer per pulse at the laser wavelengths 532 nm and 355 nm. The rate for nickel is significantly higher than that for silver...

  12. Electrochemical formation and reduction of silver oxides in alkaline media

    NARCIS (Netherlands)

    Droog, J.M.M.; Huisman, F.

    1980-01-01

    The anodic oxidation of silver electrodes in NaOH solution and the reduction of the silver oxides formed were studied by potential step chronoamperometry. Oxidation of Ag to Ag2O is a diffusion-controlled reaction, the diffusion control being established in the solid phase. Oxidation of Ag2O to AgO

  13. Synthesis and characterization of fluorophore attached silver nanoparticles

    Indian Academy of Sciences (India)

    S C G Kiruba Daniel; T Anitha Sironmani; V Tharmaraj; K Pitchumani

    2011-07-01

    Silver nanoparticles stabilized by soluble starch were synthesized and characterized. in vivo studies in rats showed no toxicity and revealed their distribution in various tissues and permeability across BBB. This starch stabilized silver nanoparticles have good biological characteristics to act as a potential promising vector for gene/drug delivery.

  14. Silver Cars Are the Safest on the Road

    Institute of Scientific and Technical Information of China (English)

    蒋保平

    2007-01-01

    <正>Silver cars are much less likely to be involved in a serious crash than cars of other colours,suggests a new study of over 1,000 cars.People driving in silver cars were 50 per cent less likely to suffer serious injury in a crash compared with drivers of white cars,the research in New Zealand found.

  15. A Hoard of Silver Currency from Achaemenid Babylon

    DEFF Research Database (Denmark)

    Reade, Julian

    1986-01-01

    Analytical appendix by M.J. Hughes and M.R. Cowell of some 25 silver items, both sheets and coins, from the hoard, includes analysis by x-ray fluorescence and atomic absorption spectroscopy. All items are of fairly good silver, with one or two parts of copper, and substantial traces of gold...

  16. Atmospheric pressure plasma enhanced spatial ALD of silver

    NARCIS (Netherlands)

    Van Den Bruele, F.J.; Smets, M.; Illiberi, A.; Creyghton, Y.; Buskens, P.; Roozeboom, F.; Poodt, P.

    2014-01-01

    The authors have investigated the growth of thin silver films using a unique combination of atmospheric process elements: spatial atomic layer deposition and an atmospheric pressure surface dielectric barrier discharge plasma source. Silver films were grown on top of Si substrates with good purity a

  17. Green Synthesis of Silver Nanoparticles Using Leaf Extracts of Clitoria ternatea and Solanum nigrum and Study of Its Antibacterial Effect against Common Nosocomial Pathogens

    Directory of Open Access Journals (Sweden)

    Narayanaswamy Krithiga

    2015-01-01

    Full Text Available Bionanotechnology has emerged up as integration between biotechnology and nanotechnology for developing biosynthetic and environmental friendly technology for synthesis of nanomaterials. 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 nanoscience deals with the preparation and study of nanoparticles in antibacterial clothing, 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 synthesize and characterize the plant mediated silver nanoparticles using Clitoria ternatea and Solanum nigrum. Further investigation of the shape and size of 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 nosocomial pathogens.

  18. Analytical Results for Municipal Biosolids Samples from a Monitoring Program near Deer Trail, Colorado (U.S.A.), 2007

    Science.gov (United States)

    Crock, J.G.; Smith, D.B.; Yager, T.J.B.; Berry, C.J.; Adams, M.G.

    2008-01-01

    Since late 1993, the Metro Wastewater Reclamation District of Denver (Metro District), a large wastewater treatment plant in Denver, Colorado, has applied Grade I, Class B biosolids to about 52,000 acres of nonirrigated farmland and rangeland near Deer Trail, Colorado (U.S.A.). In cooperation with the Metro District in 1993, the U.S. Geological Survey (USGS) began monitoring ground water at part of this site. In 1999, the USGS began a more comprehensive monitoring study of the entire site to address stakeholder concerns about the potential chemical effects of biosolids applications to water, soil, and vegetation. This more comprehensive monitoring program recently has been extended through 2010. Monitoring components of the more comprehensive study include biosolids collected at the wastewater treatment plant, soil, crops, dust, alluvial and bedrock ground water, and streambed sediment. Streams at the site are dry most of the year, so samples of streambed sediment deposited after rain were used to indicate surface-water effects. This report will present only analytical results for the biosolids samples collected at the Metro District wastewater treatment plant in Denver and analyzed during 2007. We have presented earlier a compilation of analytical results for the biosolids samples collected and analyzed for 1999 through 2006. More information about the other monitoring components is presented elsewhere in the literature. Priority parameters for biosolids identified by the stakeholders and also regulated by Colorado when used as an agricultural soil amendment include the total concentrations of nine trace elements (arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium, and zinc), plutonium isotopes, and gross alpha and beta activity. Nitrogen and chromium also were priority parameters for ground water and sediment components. In general, the objective of each component of the study was to determine whether concentrations of priority parameters (1

  19. The Social Capital of the Silver Ornaments in Northeastern, Thailand

    Directory of Open Access Journals (Sweden)

    Warit Witsrutwait

    2009-01-01

    Full Text Available Problem statement: The silver ornaments is the well known handicraft for Chum Chon Ban Choke, Tambon Khawao Sinrin, Amphoe Khawao Sinrin and Surin province. The study of social capital concerning silver ornaments at Ban Choke community, the Khmer ethnic focused on the low quality of the making the silver ornaments. The silver craftsmen earned less income because the capital productions were higher. Some craftsmen stopped making the silver ornaments to find new jobs for getting more income. That was the problem for the remaining of a silver ornaments handicraft. The purpose of the study was to study the management of social capital of silver ornament making at Chum Chon Ban Choke. Approach: It was qualitative and carried out using documentary studies, surveys, observations, and interviews and focused group discussions, 47 research informants were community and silver market leaders, silver craftsmen, shop owners, buyers, government and private personnel over looking promotion and development of silver ornaments in Surin Province. The analysis of data was done descriptively. Results: The social capital was divided into 2 categories internal and external. The internal social capital included the traditional skills of making silver ornaments and social and cultural coherence of the people. The second one came from capitalism and economic development, such as, roads, vehicles, electricity, mass media and markets. To some extent, Chum Chon Ban Choke changed. People picked up a new habit of buying goods from outside, Spending more with limited income made people go into debt. What made things even worse were low prices of their farm produce and severe droughts. The people who were in the business of silver ornaments came up with a plan bringing government and private entrepreneurs to revitalize social capital by running workshop trainings and using appropriate technology, such as, setting up a village fund, farm machinery and establish community

  20. A nano-silver enzyme electrode for organophosphorus pesticide detection.

    Science.gov (United States)

    Zheng, Qiqi; Yu, Yonghua; Fan, Kai; Ji, Feng; Wu, Jian; Ying, Yibin

    2016-08-01

    A nano-silver electrode immobilizing acetylcholinesterase (AChE) for the detection of organophosphorus (OPPs) pesticides is reported. Scanning electron microscopy (SEM) was used to characterize the surface structure of two kinds of electrodes fabricated with different sizes of silver powders and the interface between chitosan layer and nano-silver powder layer. Cyclic voltammetry was carried out to characterize the response of silver/chitosan electrode in the absence and in the presence of thiocholine (TCh). It was also used to evaluate the insulativity of the chitosan layer. An amperometric method was performed to measure the response of the electrode to TCh, which is the product of the enzymatic reaction for detecting organophosphorus pesticides indirectly. Although there are many kinds of nanoparticles, silver was chosen for its internal advantage in detecting TCh at low potential without further modification. The result shows nano-silver powder has better performance than usual silver powder, and the limit of detection of paraoxon is 4 ppb under optimized conditions. One percent (w/v) chitosan solution was used as binder for the immobilization of nano-silver powder and AChE, which made it possible for independent electrode fabrication at room temperature, whereas 3% (w/v) chitosan solution was used as insulating compound for controlling the electrode area. Unlike traditional organic insulating ink, chitosan is safe and environmentally friendly, and it is used as insulating material for the first time. The flexible nano-silver/AChE/chitosan electrode was evaluated in Chinese chives and cabbage, and the recoveries of standard addition were 105.11 and 96.41%, respectively. Owing to the antibacterial property of nano-silver and the biocompatibility, safety, and biodegradability of chitosan, the proposed method is safe, facile, environmentally friendly, and has great potential in organophosphorus pesticide detection for food safety. Graphical Abstract Current

  1. A nano-silver enzyme electrode for organophosphorus pesticide detection.

    Science.gov (United States)

    Zheng, Qiqi; Yu, Yonghua; Fan, Kai; Ji, Feng; Wu, Jian; Ying, Yibin

    2016-08-01

    A nano-silver electrode immobilizing acetylcholinesterase (AChE) for the detection of organophosphorus (OPPs) pesticides is reported. Scanning electron microscopy (SEM) was used to characterize the surface structure of two kinds of electrodes fabricated with different sizes of silver powders and the interface between chitosan layer and nano-silver powder layer. Cyclic voltammetry was carried out to characterize the response of silver/chitosan electrode in the absence and in the presence of thiocholine (TCh). It was also used to evaluate the insulativity of the chitosan layer. An amperometric method was performed to measure the response of the electrode to TCh, which is the product of the enzymatic reaction for detecting organophosphorus pesticides indirectly. Although there are many kinds of nanoparticles, silver was chosen for its internal advantage in detecting TCh at low potential without further modification. The result shows nano-silver powder has better performance than usual silver powder, and the limit of detection of paraoxon is 4 ppb under optimized conditions. One percent (w/v) chitosan solution was used as binder for the immobilization of nano-silver powder and AChE, which made it possible for independent electrode fabrication at room temperature, whereas 3% (w/v) chitosan solution was used as insulating compound for controlling the electrode area. Unlike traditional organic insulating ink, chitosan is safe and environmentally friendly, and it is used as insulating material for the first time. The flexible nano-silver/AChE/chitosan electrode was evaluated in Chinese chives and cabbage, and the recoveries of standard addition were 105.11 and 96.41%, respectively. Owing to the antibacterial property of nano-silver and the biocompatibility, safety, and biodegradability of chitosan, the proposed method is safe, facile, environmentally friendly, and has great potential in organophosphorus pesticide detection for food safety. Graphical Abstract Current

  2. Assessing Vulnerability under Uncertainty in the Colorado River Basin: The Colorado River Basin Water Supply and Demand Study

    Science.gov (United States)

    Jerla, C.; Adams, P.; Butler, A.; Nowak, K.; Prairie, J. R.

    2013-12-01

    Spanning parts of the seven states, of Arizona, California, Colorado, New Mexico, Nevada, Utah, and Wyoming, the Colorado River is one of the most critical sources of water in the western United States. Colorado River allocations exceed the long-term supply and since the 1950s, there have been a number of years when the annual water use in the Colorado River Basin exceeded the yield. The Basin is entering its second decade of drought conditions which brings challenges that will only be compounded if projections of climate change are realized. It was against this backdrop that the Colorado River Basin Water Supply and Demand Study was conducted. The Study's objectives are to define current and future imbalances in the Basin over the next 50 years and to develop and analyze adaptation and mitigation strategies to resolve those imbalances. Long-term planning in the Basin involves the integration of uncertainty with respect to a changing climate and other uncertainties such as future demand and how policies may be modified to adapt to changing reliability. The Study adopted a scenario planning approach to address this uncertainty in which thousands of scenarios were developed to encompass a wide range of plausible future water supply and demand conditions. Using Reclamation's long-term planning model, the Colorado River Simulation System, the reliability of the system to meet Basin resource needs under these future conditions was projected both with and without additional future adaptation strategies in place. System reliability metrics were developed in order to define system vulnerabilities, the conditions that lead to those vulnerabilities, and sign posts to indicate if the system is approaching a vulnerable state. Options and strategies that reduce these vulnerabilities and improve system reliability were explored through the development of portfolios. Four portfolios, each with different management strategies, were analyzed to assess their effectiveness at

  3. Facile Preparation of Silver Halide Nanoparticles as Visible Light Photocatalysts

    Directory of Open Access Journals (Sweden)

    Linfan Cui

    2015-07-01

    Full Text Available In this study, highly efficient silver halide (AgX-based photocatalysts were successfully fabricated using a facile and template-free direct-precipitation method. AgX nanoparticles, which included silver chloride (AgCl, silver bromide (AgBr and silver iodide (AgI, were synthesized using different potassium halides and silver acetate as reactive sources. The size distribution of the AgX nanopar‐ ticles was determined by the reaction time and ratio of the reagents, which were monitored by UV-vis spectra. The as- prepared AgX nanoparticles exhibited different photoca‐ talytic properties. This shows the differences for the photodegradation of methyl orange and Congo red dyes. In addition, the AgCl nanoparticle-based photocatalyst exhibited the best photocatalytic property among all three types of AgX nanoparticles that are discussed in this study. Therefore, it is a good candidate for removing organic pollutants.

  4. Preparation and characterization of polyimide/silica/silver composite films

    Institute of Scientific and Technical Information of China (English)

    Ning LUO; Zhanpeng WU; Nanxiang MOU; Lizhong JIANG; Dezhen WU

    2008-01-01

    Polyimide/silica/silver hybrid films were pre-pared by the sol-gel method combined with in situ single-stage self-metallization technique.The structure of polyi-mide films in the thermal curing process and the influence of silica content on the migration and aggregation of silver particles to the surface of hybrid films were investigated.The hybrid films were characterized by transmission elec-tron microscopy,dynamic mechanical thermal analysis,Fourier transform infrared spectroscopy,ultraviolet visible spectroscopy and mechanical measurements.The results indicated that there was no degradation of the polyimide matrix after the formation of silica and silver particles.Silica acted as the nucleus for the silver particles.With increasing silica content,more and more silver particles were kept in the hybrid films instead of being migrated onto the surface of the hybrid films and the reflections of hybrid films decreased gradually.

  5. Effects of Surface Coating on Physical Properties of Silver Nanoparticles

    Science.gov (United States)

    Tariq, M.; Hasnain, S. M.

    2015-08-01

    Polymer-coated nanoparticles improve the stability of materials against aggregation and enhance the physical properties, thus making it possible to use different applications in vast fields of science. In this work, silver nanoparticles were synthesized by a chemical reduction method and were further coated with the polymers polyvinyl alcohol (PVA) and polystyrene (PS). The influence of the polymer coating on the optical and electrical properties of the silver nanoparticles were investigated and compared with that of as-prepared silver nanoparticles. The nature of the prepared silver nanoparticles in the face-centered cubic structure is confirmed by peaks in the x-ray diffraction pattern. The temperature dependence of resistivity of the silver nanoparticles exhibit semiconducting behavior in the temperature range 100-300 K.

  6. Sonochemical Synthesis of Silver Nanoparticles Using Starch: A Comparison

    Science.gov (United States)

    Smita, Kumari; Cumbal, Luis; Debut, Alexis; Pathak, Ravinandan Nath

    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 electron diffraction (SAED) confirmed partial crystalline and amorphous nature of silver nanoparticles. Silver nanoparticles synthesized in this manner can be used for synthesis of 2-aryl substituted benzimidazoles which have numerous biomedical applications. The optimized reaction conditions include 10 ml of 1 mM AgNO3, 25 mg starch, 11 pH range, and sonication for 20 min at room temperature. PMID:24587771

  7. Sonochemical Synthesis of Silver Nanoparticles Using Starch: A Comparison

    Directory of Open Access Journals (Sweden)

    Brajesh Kumar

    2014-01-01

    Full Text Available 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 electron diffraction (SAED confirmed partial crystalline and amorphous nature of silver nanoparticles. Silver nanoparticles synthesized in this manner can be used for synthesis of 2-aryl substituted benzimidazoles which have numerous biomedical applications. The optimized reaction conditions include 10 ml of 1 mM AgNO3, 25 mg starch, 11 pH range, and sonication for 20 min at room temperature.

  8. ELLIPSOMETRIC STUDY OF SEMITRANSPARENT SILVER LAYERS DEPOSITED ON GLASS

    Directory of Open Access Journals (Sweden)

    Víctor Toranzos

    2014-12-01

    Full Text Available Using ellipsometry, the film structure is characterized by optical indices n, k (visible region, 450 nm <  < 580 nm and the thickness (15 < d < 35 nm. The optical indices change with the quantity of silver deposited, obtaining effective indices of 1.0 < n < 1.8 and 1.6 < k < 2.6 to the smaller deposits that belong to a volumetric fraction between 0.35 and 0.5 of silver in the air. An effective optical thickness film decrease is observed when the silver volumetric fraction increases, and a thickness increase with close indices to solid silver when the deposited silver increases. Optical and effective medium theory indices are compared.

  9. Decoration of activated carbon nanotubes by assembling nano-silver

    Institute of Scientific and Technical Information of China (English)

    Chen-sha Li; Bin-song Wang; Ying-jie Qiao; Wei-zhe Lu; Ji Liang

    2009-01-01

    A facile solution processed strategy of synthesizing nano silver assembled on carbon nanotubes (CNTs) at room tempera-ture was put forward. Activated carbon nanotubes were used as precursors for preparing silver-decorated nanotubes. The nature of the decorated nanotubes was studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and en-ergy-dispersive X-ray spectroscopy (EDX). The inert surfaces of carbon nanotubes were activated by introducing catalytic nuclei via an oxidation-sensitization-activation approach. Activated carbon nanotubes catalyzed the metal deposition specifically onto their surfaces upon immersion in electroless plating baths. The method produced nanotubes decorated with silver. The extent of silver decoration was found to be dependent on fabrication conditions. Dense nano silver assembled on nanotube surfaces could be ob-tained by keeping a low reaction rate in the solution phase. The results here show that this method is an efficient and simple means of achieving carbon nanotubes being assembled by nano metal.

  10. Visualizing the mobility of silver during catalytic soot oxidation

    DEFF Research Database (Denmark)

    Gardini, Diego; Christensen, Jakob M.; Damsgaard, Christian Danvad;

    2016-01-01

    The catalytic activity and mobility of silver nanoparticles used as catalysts in temperature programmed oxidation of soot:silver (1:5 wt:wt) mixtures have been investigated by means of flow reactor experiments and in situ environmental transmission electron microscopy (ETEM). The carbon oxidation...... temperature was significantly lower compared to uncatalyzed soot oxidation with soot and silver loosely stirred together (loose contact) and lowered further with the two components crushed together (tight contact). The in situ TEM investigations revealed that the silver particles exhibited significant...... mobility during the soot oxidation, and this mobility, which increases the soot/catalyst contact, is expected to be an important factor for the lower oxidation temperature. In the intimate tight contact mixture the initial dispersion of the silver particles is greater,,and the onset of mobility occurs...

  11. Preparation and Storage of Silver Nanoparticles in Aqueons Polymers

    Institute of Scientific and Technical Information of China (English)

    SONG,Weihong; ZHANG,Xiaoxiao; YIN,Hongzong; SA,Panpan; LIU,Xiaoyan

    2009-01-01

    Silver nanoparticles were obtained by a chemical reduction method using aqueous polymers as dispersant and characterized by UV-Vis spectroscopy,transmission electron microscopy (TEM) and light-scattering spectroscopy.Solid polymer films containing the silver nanoparticles were also prepared after evaporating the solvent,and then dried with existing polymer.The stability of the silver nanoparticles was compared between primary fresh silver nanoparticle solution and redissolved solid polymer films by UV-Vis spectroscopy.The particle size ranged from 5 to l0 rim,and no obvious differences were found.Therefore,preparing solid nano-Ag/polymer was a novel and useful method in storage of silver nanoparticles.

  12. Compositional study of Parthian silver coins using PIXE technique

    Energy Technology Data Exchange (ETDEWEB)

    Hajivaliei, M., E-mail: mhaji65@yahoo.com [Department of Physics, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of); Khademi Nadooshan, F. [Department of Archaeology, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2012-10-15

    The study of the elemental composition of silver coins minted in the Ecbatana mint houses during the Parthian period can help to elucidate key questions such as provenance of the silver metal and the socio-economic situation of that period. Commercial activity and population growth increased the demand for silver, forcing the Parthian to look for new sources of this metal. The aim of this work is to study the chemical composition of some Parthian coins to find any relation between the mines used for extraction of silver and the actual silver coins minted at that time. Using PIXE technique, the metallic elements Ti, Fe, Cu, Zn, Ag, Au, and Pb were observed. The results show that Parthian's kings used almost two types of mines for their coins.

  13. Antimicrobial Bacterial Cellulose-Silver Nanoparticles Composite Membranes

    Directory of Open Access Journals (Sweden)

    Hernane S. Barud

    2011-01-01

    Full Text Available 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 together with swelling behavior for water were considered. TEA concentration was observed to be important in order to obtain only Ag particles and not a mixture of silver oxides. It was also observed to control particle size and amount of silver contents in bacterial cellulose. The composite membranes exhibited strong antimicrobial activity against Gram-negative and Gram-positive bacteria.

  14. Silver nanoparticles and silver nitrate induce high toxicity to Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Fabianne, E-mail: ribeiro.f@ua.pt [Department of Biology and CESAM, University of Aveiro. Campus Universitario de Santiago, 3810-193. Aveiro (Portugal); Gallego-Urrea, Julián Alberto [Department of Chemistry and Molecular Biologyx, University of Gothenburg, Kemivägen 4, 41296 Gothenburg (Sweden); Jurkschat, Kerstin; Crossley, Alison [Department of Materials, Oxford University Begbroke Science Park OX5 1PF (United Kingdom); Hassellöv, Martin [Department of Chemistry and Molecular Biologyx, University of Gothenburg, Kemivägen 4, 41296 Gothenburg (Sweden); Taylor, Cameron [Department of Materials, Oxford University Begbroke Science Park OX5 1PF (United Kingdom); Soares, Amadeu M.V.M.; Loureiro, Susana [Department of Biology and CESAM, University of Aveiro. Campus Universitario de Santiago, 3810-193. Aveiro (Portugal)

    2014-01-01

    Silver nanoparticles (AgNP) have gained attention over the years due to the antimicrobial function of silver, which has been exploited industrially to produce consumer goods that vary in type and application. Undoubtedly the increase of production and consumption of these silver-containing products will lead to the entry of silver compounds into the environment. In this study we have used Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio as model organisms to investigate the toxicity of AgNP and AgNO{sub 3} by assessing different biological endpoints and exposure periods. Organisms were exposed following specific and standardized protocols for each species/endpoints, with modifications when necessary. AgNP were characterized in each test-media by Transmission Electron Microscopy (TEM) and experiments were performed by Dynamic Light Scattering (DLS) to investigate the aggregation and agglomeration behavior of AgNP under different media chemical composition and test-period. TEM images of AgNP in the different test-media showed dissimilar patterns of agglomeration, with some agglomerates inside an organic layer, some loosely associated particles and also the presence of some individual particles. The toxicity of both AgNO{sub 3} and AgNP differ significantly based on the test species: we found no differences in toxicity for algae, a small difference for zebrafish and a major difference in toxicity for Daphnia magna. - Highlights: •Effects of silver nanoparticles and nitrate were compared in three aquatic species. •The presence of food on the immobilization assay for Daphnia magna significantly decreased AgNP toxicity. •AgNP and AgNO{sub 3} differ in toxicity according to the test species and endpoint. •AgNP and AgNO{sub 3} induced dissimilar abnormalities on zebrafish embryos' development. •AgNP behavior in the test media will rule its bioavailability and uptake and therefore toxicity.

  15. Silver nanorod arrays for photocathode applications

    Energy Technology Data Exchange (ETDEWEB)

    Vilayurganapathy, Subramanian [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Western Michigan Univ., Kalamazoo MI (United States); Nandasiri, Manjula I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Western Michigan Univ., Kalamazoo MI (United States); Joly, Alan G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); El-Khoury, Patrick Z. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Varga, Tamas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Coffey, Greg W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schwenzer, Birgit [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Pandey, Archana [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kayani, Asghar N. [Western Michigan Univ., Kalamazoo MI (United States); Hess, Wayne P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Thevuthasan, Suntharampillai [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-10-16

    In this study, we explore the possibility of using plasmonic Ag nanorod arrays featuring enhanced photoemission as high-brightness photocathode material. Silver nanorod arrays are synthesized by the DC electrodeposition method and their dimensionality, uniformity, crystallinity and oxide/impurity content are characterized. These Ag nanorod arrays exhibit greatly enhanced two-photon photoemission under 400 nm femtosecond pulsed laser excitation. Plasmonic field enhancement in the array produces photoemission hot spots that are mapped using photoemission electron microscopy (PEEM). The relative photoemission enhancement of nanorod array hot spots relative to that of a flat Ag thin film is found to range between 102 and 3 x 103.

  16. Graphene-protected copper and silver plasmonics

    DEFF Research Database (Denmark)

    Kravets, V. G.; Jalil, R.; Kim, Y. J.;

    2014-01-01

    suitable for plasmonic applications. To this end, there has been a continuous search for alternative plasmonic materials that are also compatible with complementary metal oxide semiconductor technology. Here we show that copper and silver protected by graphene are viable candidates. Copper films covered...... with one to a few graphene layers show excellent plasmonic characteristics. They can be used to fabricate plasmonic devices and survive for at least a year, even in wet and corroding conditions. As a proof of concept, we use the graphene-protected copper to demonstrate dielectric loaded plasmonic...

  17. Engineering Silver Nanoparticles: Towards a Tunable Antimicrobial

    Science.gov (United States)

    Puppala, Hema Lakshmi

    Overwhelming production of commercially available products containing silver nanoparticles (AgNPs) underscores the studies determining their fate in the environment. In order to regulate the use, assess the environmental impact and develop eco-responsible silver products, models that can predict AgNP toxicity based on physicochemical properties are vital. With that vision, this thesis developed well-characterized model libraries of uniform AgNPs stabilized with oleate in the range of 2-45 nm diameter with variable surface coating and investigated the dissolution properties that link AgNP structure to antimicrobial activity. High temperature organic synthesis allowed controlled growth of AgNPs (sigmaOECD medium), thereby increasing the shelf life. In addition, size, surface coating, pH of the medium and grafting density of the polymer mediated the dissolution of AgNPs. For instance, the rate of dissolution was decreased by 40% when the polymer coating possessed a mushroom conformation and increased with reducing core size. Analogous to dissolution, physicochemical properties also influenced the antimicrobial activity which were studied by minimum inhibitory concentration (MIC) and bactericidal efficacy assays. For example, surface passivation with mPEGSH prevented the oxidation of active silver atoms on the surface, and resulted in reduced toxicity against E. coli. Moreover citrate stabilized AgNPs when surface modified with mPEGSH had reduced toxicity, which was correlated with residual Ag+ in AgNP solution. Therefore this study demonstrates that processes in the environment that increase stability of AgNPs could make them more persistent due to low dissolution. Furthermore, the size and surface chemistry effects of AgNPs studied here make the intrinsic antimicrobial property of silver tunable and hence more versatile. This work also served as a material support for research on investigating toxicity of AgNPs to C. elegans, Daphnia Magna, Populus and Arabidopsis

  18. Ab Initio Study on Hypothetical Silver Nitride

    Institute of Scientific and Technical Information of China (English)

    DELIGOZ Engin; COLAKOGLU Kemal; CIFTCI Yasemin Oztekin

    2008-01-01

    We perform the ab initio calculations based on norm-conserving pseudopotentials and density functional theory to investigate the structural, elastic, and thermodynamical properties for silver nitride (AgN) compound that is a member of the 4d transition metal group and has not been synthesized yet. The obtained results are compared with the other available theoretical data, and the agreement is, generally, quite good. We also present the pressure-dependent behaviour of some mechanical and thermodynamical properties for the same compounds.

  19. Green chemical synthesis of silver nanomaterials with maltodextrin.

    Energy Technology Data Exchange (ETDEWEB)

    Tallant, David Robert; Lu, Ping; Lambert, Timothy N.; Bell, Nelson Simmons

    2010-11-01

    Silver nanomaterials have significant application resulting from their optical properties related to surface enhanced Raman spectroscopy, high electrical conductivity, and anti-microbial impact. A 'green chemistry' synthetic approach for silver nanomaterials minimizes the environmental impact of silver synthesis, as well as lowers the toxicity of the reactive agents. Biopolymers have long been used for stabilization of silver nanomaterials during synthesis, and include gum Arabic, heparin, and common starch. Maltodextrin is a processed derivative of starch with lower molecular weight and an increase in the number of reactive reducing aldehyde groups, and serves as a suitable single reactant for the formation of metallic silver. Silver nanomaterials can be formed under either a thermal route at neutral pH in water or by reaction at room temperature under more alkaline conditions. Deposited silver materials are formed on substrates from near neutral pH solutions at low temperatures near 50 C. Experimental conditions based on material concentrations, pH and reaction time are investigated for development of deposited films. Deposit morphology and optical properties are characterized using SEM and UV-vis techniques. Silver nanoparticles are generated under alkaline conditions by a dissolution-reduction method from precipitated silver (II) oxide. Synthesis conditions were explored for the rapid development of stable silver nanoparticle dispersions. UV-vis absorption spectra, powder X-ray diffraction (PXRD), dynamic light scattering (DLS), and transmission electron microscopy (TEM) techniques were used to characterize the nanoparticle formation kinetics and the influence of reaction conditions. The adsorbed content of the maltodextrin was characterized using thermogravimetric analysis (TGA).

  20. Novel, silver-ion-releasing nanofibrous scaffolds exhibit excellent antibacterial efficacy without the use of silver nanoparticles.

    Science.gov (United States)

    Mohiti-Asli, Mahsa; Pourdeyhimi, Behnam; Loboa, Elizabeth G

    2014-05-01

    Nanofibers, with their morphological similarities to the extracellular matrix of skin, hold great potential for skin tissue engineering. Over the last decade, silver nanoparticles have been extensively investigated in wound-healing applications for their ability to provide antimicrobial benefits to nanofibrous scaffolds. However, the use of silver nanoparticles has raised concerns as these particles can penetrate into the stratum corneum of skin, or even diffuse into the cellular plasma membrane. We present and evaluate a new silver ion release polymeric coating that we have found can be applied to biocompatible, biodegradable poly(l-lactic acid) nanofibrous scaffolds. Using this compound, custom antimicrobial silver-ion-releasing nanofibers were created. The presence of a uniform, continuous silver coating on the nanofibrous scaffolds was verified by XPS analysis. The antimicrobial efficacy of the antimicrobial scaffolds against Staphylococcus aureus and Escherichia coli bacteria was determined via industry-standard AATCC protocols. Cytotoxicity analyses of the antimicrobial scaffolds toward human epidermal keratinocytes and human dermal fibroblasts were performed via quantitative analyses of cell viability and proliferation. Our results indicated that the custom antimicrobial scaffolds exhibited excellent antimicrobial properties while also maintaining human skin cell viability and proliferation for silver ion concentrations below 62.5μgml(-1) within the coating solution. This is the first study to show that silver ions can be effectively delivered with nanofibrous scaffolds without the use of silver nanoparticles.

  1. Crustal structure across the Colorado Basin, offshore Argentina

    Science.gov (United States)

    Franke, Dieter; Neben, Soenke; Schreckenberger, Bernd; Schulze, Albrecht; Stiller, Manfred; Krawczyk, Charlotte M.

    2006-06-01

    The geology of the wide shelves surrounding the South Atlantic is closely linked to the kinematics and history of the opening of the ocean. However, several wide sedimentary basins, which developed along the margins show peculiarities that are not yet understood in the context of the evolution of the South Atlantic. The Colorado Basin, a wide sedimentary basin on the broad shelf of Argentina, extends in EW direction. The basin's evolution oblique or orthogonal to the continent-ocean boundary indicates that it is not a product of simple progressive extension and crustal thinning. In addition a basement high, paralleling the continental margin and separating the Colorado Basin from the deep-sea basin is a common interpretation. These findings are hardly in accordance with the idea that the Colorado Basin is an extensional basin that developed in conjunction with the early E-W opening phase of the South Atlantic in the Late Jurassic/Early Cretaceous. The composition, type, and structure of the basement, key points for the evaluation of the basins evolution, are widely speculative. In this context multichannel seismic reflection data from the Argentine Shelf and a 665-km-long onshore-offshore refraction profile, running across the Colorado Basin onto the coast are discussed in combination with gravity data. The stratigraphy for the sedimentary successions was adopted from the literature and the reflection seismic marker horizons formed besides the interval velocities the input for the starting model for refraction seismic traveltime modelling. The modelling strategy was an iterative procedure between refraction seismic traveltime and gravity modelling. The preparation of the density models was coarsely orientated on published velocity-density relations. The modelling results are in favour of a continuation of the main onshore geological features beneath the sedimentary infill of the Colorado Basin. We interpret the basement along the line from west to east as offshore

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

    Directory of Open Access Journals (Sweden)

    Kevin G. Welner

    2004-07-01

    Full Text Available 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 already enrolled in private schools. In fact, this law, as well as any revised law with similar eligibility provisions, would actually cost taxpayers an additional $10 million per year once fully implemented because the eligibility provision provides little more than a short-term damper on the law's long-term fiscal impact.

  3. Capital in the Twenty-First Century

    DEFF Research Database (Denmark)

    Hansen, Per H.

    2014-01-01

    Review essay on: Capital in the Twenty-First Century. By Thomas Piketty . Translated by Arthur Goldhammer . Cambridge, Mass.: The Belknap Press of Harvard University Press, 2014. viii + 685 pp......Review essay on: Capital in the Twenty-First Century. By Thomas Piketty . Translated by Arthur Goldhammer . Cambridge, Mass.: The Belknap Press of Harvard University Press, 2014. viii + 685 pp...

  4. 21st Century Skills Map: Science

    Science.gov (United States)

    Partnership for 21st Century Skills, 2008

    2008-01-01

    This 21st Century Skills Map is the result of hundreds of hours of research, development and feedback from educators and business leaders across the nation. The Partnership for 21st Century Skills has issued this map for the core subject of Science.

  5. 21st Century Skills Map: Geography

    Science.gov (United States)

    Partnership for 21st Century Skills, 2009

    2009-01-01

    This 21st Century Skills Map is the result of hundreds of hours of research, development and feedback from educators and business leaders across the nation. The Partnership for 21st Century Skills has issued this map for the core subject of Geography.

  6. 21st Century Skills Map: The Arts

    Science.gov (United States)

    Dean, Colleen; Ebert, Christie M. Lynch; McGreevy-Nichols, Susan; Quinn, Betsy; Sabol, F. Robert; Schmid, Dale; Shauck, R. Barry; Shuler, Scott C.

    2010-01-01

    This 21st Century Skills Map is the result of hundreds of hours of research, development and feedback from educators and business leaders across the nation. The Partnership for 21st Century Skills has issued this map for the core subject of the Arts.

  7. 21st Century Skills Map: Social Studies

    Science.gov (United States)

    Partnership for 21st Century Skills, 2007

    2007-01-01

    This 21st Century Skills Map is the result of hundreds of hours of research, development and feedback from educators and business leaders across the nation. The Partnership for 21st Century Skills has issued this map for the core subject of Social Studies.

  8. Pedagogical Implementation of 21st Century Skills

    Science.gov (United States)

    Jacobson-Lundeberg, Vera

    2016-01-01

    This paper examines students' perceptions of how intentionally taught 21st century skills have transformed their lives. Personal development education (PDE) encompasses interpersonal and interaction skills that are required for students to function and succeed in global-oriented 21st century colleges and careers. The Common Core State Standards…

  9. 21st Century Skills Map: World Languages

    Science.gov (United States)

    Partnership for 21st Century Skills, 2011

    2011-01-01

    This 21st Century Skills Map is the result of hundreds of hours of research, development and feedback from educators and business leaders across the nation. The Partnership for 21st Century Skills has issued this map for the core subject of World Languages. [Funding for this paper was provided by EF Education.

  10. 21st Century Skills Map: English

    Science.gov (United States)

    Partnership for 21st Century Skills, 2008

    2008-01-01

    This 21st Century Skills Map is the result of hundreds of hours of research, development and feedback from educators and business leaders across the nation. The Partnership for 21st Century Skills has issued this map for the core subject of English.

  11. The Century of Education. CEE DP 109

    Science.gov (United States)

    Morrisson, Christian; Murtin, Fabrice

    2009-01-01

    Global economic transformations have never been as dramatic as in the twentieth century. Most countries have experienced radical changes in the standards of income per capita, technology, fertility, mortality, income inequality and the extent of democracy in the course of the past century. It is the goal of many disciplines--economics, history,…

  12. An Unfashionable Rhetoric in the Fifteenth Century.

    Science.gov (United States)

    Woods, Marjorie Curry

    1989-01-01

    Reveals the continued importance of medieval rhetorical pedagogy throughout the high Middle Ages and early Renaissance by exploring the fifteenth-century popularity, uses of, and references to Geoffrey of Vinsauf's "Poetria nova" (a thirteenth-century verse treatise on the composition of poetry according to rhetorical principles). (SR)

  13. Breeding densities and migration periods of common snipe in Colorado

    Science.gov (United States)

    Johnson, B.R.; Ryder, R.A.

    1977-01-01

    Breeding densities and migration periods of Common Snipe in Colorado were investigated in 1974-75. Sites studied were near Fort Collins and in North Park, both in north central Colorado; in the Yampa Valley in northwestern Colorado; and in the San Luis Valley in south central Colorado....Estimated densities of breeding snipe based on censuses conducted during May 1974 and 1975 were, by region: 1.3-1.7 snipe/ha near Fort Collins; 0.6 snipe/ha in North Park; 0.5-0.7 snipe/ha in the Yampa Valley; and 0.5 snipe/ha in the San Luis Valley. Overall mean densities were 06 and 0.7 snipe/ha in 1974 and 1975 respectively. On individual study sites, densities of snipe ranged from 0.2 to 2.1 snipe/ha. Areas with shallow, stable, discontinuous water levels, sparse, short vegetation, and soft organic soils had the highest densities.....Twenty-eight nests were located having a mean clutch size of 3.9 eggs. Estimated onset of incubation ranged from 2 May through 4 July. Most nests were initiated in May.....Spring migration extended from late March through early May. Highest densities of snipe were recorded in all regions during l&23 April. Fall migration was underway by early September and was completed by mid-October with highest densities occurring about the third week in September. High numbers of snipe noted in early August may have been early migrants or locally produced juveniles concentrating on favorable feeding areas.

  14. Damming Grand Canyon: The 1923 USGS Colorado River Expedition

    OpenAIRE

    Boyer, Diane E.; Webb, Robert H.

    2007-01-01

    In 1923, America paid close attention, via special radio broadcasts, newspaper headlines, and cover stories in popular magazines, as a government party descended the Colorado to survey Grand Canyon. Fifty years after John Wesley Powell's journey, the canyon still had an aura of mystery and extreme danger. At one point, the party was thought lost in a flood. Something important besides adventure was going on. Led by Claude Birdseye and including colorful characters such as early river-runner E...

  15. The historical distribution of Gunnison Sage-Grouse in Colorado

    Science.gov (United States)

    Braun, Clait E.; Oyler-McCance, Sara J.; Nehring, Jennifer A.; Commons, Michelle L.; Young, Jessica R.; Potter, Kim M.

    2014-01-01

    The historical distribution of Gunnison Sage-Grouse (Centrocercus minimus) in Colorado is described based on published literature, observations, museum specimens, and the known distribution of sagebrush (Artemisia spp.). Historically, Gunnison Sage-Grouse were widely but patchily distributed in up to 22 counties in south-central and southwestern Colorado. The historical distribution of this species was south of the Colorado-Eagle river drainages primarily west of the Continental Divide. Potential contact areas with Greater Sage-Grouse (C. urophasianus) were along the Colorado-Eagle river system in Mesa, Garfield, and Eagle counties, west of the Continental Divide. Gunnison Sage-Grouse historically occupied habitats that were naturally highly fragmented by forested mountains and plateaus/mesas, intermountain basins without robust species of sagebrush, and river systems. This species adapted to use areas with more deciduous shrubs (i.e., Quercus spp., Amelanchier spp., Prunus spp.) in conjunction with sagebrush. Most areas historically occupied were small, linear, and patchily distributed within the overall landscape matrix. The exception was the large intermountain basin in Gunnison, Hinsdale, and Saguache counties. The documented distribution east of the Continental Divide within the large expanse of the San Luis Valley (Alamosa, Conejos, Costilla, and Rio Grande counties) was minimal and mostly on the eastern, northern, and southern fringes. Many formerly occupied habitat patches were vacant by the mid 1940s with extirpations continuing to the late 1990s. Counties from which populations were recently extirpated include Archuleta and Pitkin (1960s), and Eagle, Garfield, Montezuma, and Ouray (1990s).

  16. Infant feeding practices of migrant farmlaborers in Northern Colorado

    OpenAIRE

    O'Malley, Beth

    1989-01-01

    The infant feeding practices and associated environment of 49 infants (6-23 months) of migrant farm laborers in Northern Colorado were investigated during the summer of 1987. Information was collected on 1) breastfeeding practices, 2) introduction of foods and liquids, 3) nutrition and health practices and inadequacies, 4) home living environment, 5) health history, and 6) demographics. Data on the sources of food and nutrition information was collected regarding the 1) u...

  17. Cooperative Meat Packing, lessons learned from Sterling Colorado Beef Company

    OpenAIRE

    Ward, Clement E.

    1981-01-01

    Integration into meatpacking is a marketing alternative for livestock producers. For those considering such a step, Sterling Colorado Beef Co. provides a valuable learning experience. Feeders willing to commit capital, cattle, and time established the cooperative. Members said primary benefits were having a guaranteed market outlet and receiving a fair market price, rather than receiving a higher price or obtaining additional returns from meatpacking. Members attributed the cooperative's succ...

  18. Preparation of Phenolic Resin/Silver Nanocomposites via in-situ Reduction

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Resol type phenolic resin/silver nanocomposite was prepared by in-situ reduction method, in which the curing of phenolic resin and the formation of silver nano-particles took place simultaneously. The silver ions were reduced completely to silver nanoparticles, which were dispersed homogeneously in the resin matrix with narrow size distribution.

  19. Bacterial inhibiting surfaces caused by the effects of silver release and/or electrical field

    DEFF Research Database (Denmark)

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

    2008-01-01

    In this study, silver-palladium surfaces and silver-bearing stainless steels were designed and investigated focusing on electrochemical principles to form inhibiting effects on planktonic and/or biofilm bacteria in water systems. Silver-resistant Escherichia coli and silver-sensitive E. coli were...

  20. UV-laser-induced nanoclusters in silver ion-exchanged soda-lime silicate glass

    International Nuclear Information System (INIS)

    Excimer-laser irradiation (ArF: 193 nm) was performed on silver-exchanged commercial soda-lime silicate glass. Silver nanoclusters were obtained with an average size dependent on the irradiation time, without subsequent heating. Laser irradiation induces the reduction of silver ions and promotes the silver atoms aggregation

  1. Preparation of silver nanocrystals in microemulsion by the γ-radiation method

    Science.gov (United States)

    Hongkai, Wu; Xiangling, Xu; Xuewe, Ge; Zhicheng, Zhang

    1997-12-01

    Silver colloids of well-defined shape, size were synthesized by γ-ray irradiating silver salt in reversed microemulsions, and then pure silver dry powders were obtained. The sols were studied by absorption spectroscopy, and the silver powders were characterized by Transmission Electron Micrographs (TEM) and X-ray Diffraction (XRD). The effect of radiation dose and aging time was discussed.

  2. Traveltime characteristics of Gore Creek and Black Gore Creek, upper Colorado River basin, Colorado

    Science.gov (United States)

    Gurdak, Jason J.; Spahr, Norman E.; Szmajter, Richard J.

    2002-01-01

    In the Rocky Mountains of Colorado, major highways are often constructed in stream valleys. In the event of a vehicular accident involving hazardous materials, the close proximity of highways to the streams increases the risk of contamination entering the streams. Recent population growth has contributed to increased traffic volume along Colorado highways and has resulted in increased movement of hazardous materials, particularly along Interstate 70. Gore Creek and its major tributary, Black Gore Creek, are vulnerable to such contamination from vehicular accidents along Interstate 70. Gore Creek, major tributary of the Eagle River, drains approximately 102 square miles, some of which has recently undergone significant urban development. The headwaters of Gore Creek originate in the Gore Range in the eastern part of the Gore Creek watershed. Gore Creek flows west to the Eagle River. Beginning at the watershed boundary on Vail Pass, southeast of Vail Ski Resort, Interstate 70 parallels Black Gore Creek and then closely follows Gore Creek the entire length of the watershed. Interstate 70 crosses Gore Creek and tributaries 20 times in the watershed. In the event of a vehicular accident involving a contaminant spill into Gore Creek or Black Gore Creek, a stepwise procedure has been developed for water-resource managers to estimate traveltimes of the leading edge and peak concentration of a conservative contaminant. An example calculating estimated traveltimes for a hypothetical contaminant release in Black Gore Creek is provided. Traveltime measurements were made during May and September along Black Gore Creek and Gore Creek from just downstream from the Black Lakes to the confluence with the Eagle River to account for seasonal variability in stream discharge. Fluorometric dye injection of rhodamine WT and downstream dye detection by fluorometry were used to measure traveltime characteristics of Gore Creek and Black Gore Creek. During the May traveltime measurements

  3. Cost effectiveness of the 1993 Model Energy Code in Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, R.G.

    1995-06-01

    This report documents an analysis of the cost effectiveness of the Council of American Building Officials` 1993 Model Energy Code (MEC) building thermal-envelope requirements for single-family homes in Colorado. The goal of this analysis was to compare the cost effectiveness of the 1993 MEC to current construction practice in Colorado based on an objective methodology that determined the total life-cycle cost associated with complying with the 1993 MEC. This analysis was performed for the range of Colorado climates. The costs and benefits of complying with the 1993 NIEC were estimated from the consumer`s perspective. The time when the homeowner realizes net cash savings (net positive cash flow) for homes built in accordance with the 1993 MEC was estimated to vary from 0.9 year in Steamboat Springs to 2.4 years in Denver. Compliance with the 1993 MEC was estimated to increase first costs by $1190 to $2274, resulting in an incremental down payment increase of $119 to $227 (at 10% down). The net present value of all costs and benefits to the home buyer, accounting for the mortgage and taxes, varied from a savings of $1772 in Springfield to a savings of $6614 in Steamboat Springs. The ratio of benefits to costs ranged from 2.3 in Denver to 3.8 in Steamboat Springs.

  4. Geothermal resource assessment of western San Luis Valley, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Zacharakis, Ted G.; Pearl, Richard Howard; Ringrose, Charles D.

    1983-01-01

    The Colorado Geological Survey initiated and carried out a fully integrated assessment program of the geothermal resource potential of the western San Luis Valley during 1979 and 1980. The San Luis Valley is a large intermontane basin located in southcentral Colorado. While thermal springs and wells are found throughout the Valley, the only thermal waters found along the western part of the Valley are found at Shaw Warm Springs which is a relatively unused spring located approximately 6 miles (9.66 km) north of Del Norte, Colorado. The waters at Shaws Warm Spring have a temperature of 86 F (30 C), a discharge of 40 gallons per minute and contain approximately 408 mg/l of total dissolved solids. The assessment program carried out din the western San Luis Valley consisted of: soil mercury geochemical surveys; geothermal gradient drilling; and dipole-dipole electrical resistivity traverses, Schlumberger soundings, Audio-magnetotelluric surveys, telluric surveys, and time-domain electro-magnetic soundings and seismic surveys. Shaw Warm Springs appears to be the only source of thermal waters along the western side of the Valley. From the various investigations conducted the springs appear to be fault controlled and is very limited in extent. Based on best evidence presently available estimates are presented on the size and extent of Shaw Warm Springs thermal system. It is estimated that this could have an areal extent of 0.63 sq. miles (1.62 sq. km) and contain 0.0148 Q's of heat energy.

  5. Deep mantle forces and the uplift of the Colorado Plateau

    Energy Technology Data Exchange (ETDEWEB)

    Moucha, R; Forte, A M; Rowley, D B; Mitrovica, J X; Simmons, N A; Grand, S P

    2009-06-23

    Since the advent of plate tectonics, it has been speculated that the northern extension of the East Pacific Rise, specifically its mantle source, has been over-ridden by the North American Plate in the last 30 Myrs. Consequently, it has also been postulated that the opening of the Gulf of California, the extension in the Basin and Range province, and the uplift of the Colorado Plateau are the resulting continental expressions of the over-ridden mantle source of the East Pacific Rise. However, only qualitative models based solely on surface observations and heuristic, simplified conceptions of mantle convection have been used in support or against this hypothesis. We introduce a quantitative model of mantle convection that reconstructs the detailed motion of a warm mantle upwelling over the last 30 Myrs and its relative advance towards the interior of the southwestern USA. The onset and evolution of the crustal uplift in the central Basin and Range province and the Colorado Plateau is determined by tracking the topographic swell due to this mantle upwelling through time. We show that (1) the extension and magmatism in the central Basin and Range province between 25 and 10 Ma coincides with the reconstructed past position of this focused upwelling, and (2) the southwestern portion of the Colorado Plateau experienced significant uplift between 10 Ma and 5 Ma that progressed towards the northeastern portion of the plateau. These uplift estimates are consistent with a young, ca. 6 Ma, Grand Canyon model and the recent commencement of mafic magmatism.

  6. Medicine in 21st Century

    Institute of Scientific and Technical Information of China (English)

    YangBinghui

    2001-01-01

    An ancient Chinese theme of "Shen Nong tasted hundred herbs and confronted seventy toxicities a day" means generally that medicine was created by the ancient labor people, although there's no trace of the real Shen Nong. Accordingly some animals would take certain herbs for stopping traumatic bleeding just as our ancestors done. Medicine iniated a long time ago but the development of modern medicine is really a little bit more than hundred years, Pasteur discovered bacteria and reported in 1857, not yet 150 years from now. Virchow discovered cell cleavage and thus founded modern basic cellular pathology somewhat a year later than the former. Mendels bean test opened a new era for genetic research and concluded in 1863. Roentgen discovered X-ray in 1895 and We've celebrated the 100th anniversary of the X-ray discovery several years ago. The earliest application of penicillin was in 1940, not yet 60 years ago. The medicine possesses a jumping development during the recent half century in association with the advancement of synthetic chemistry, electronic and bioscientific technolgy.

  7. Magnetic Properties of Iron Clusters in Silver

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M., E-mail: elzain@squ.edu.om; Al Rawas, A.; Yousif, A.; Gismelseed, A.; Rais, A.; Al-Omari, I.; Bouziane, K. [College of Science, Department of Physics (Oman); Widatallah, H. [Khartoum University, Department of Physics, Faculty of Science (Sudan)

    2004-12-15

    The discrete variational method is used to study the effect of interactions of iron impurities on the magnetic moments, hyperfine fields and isomer shifts at iron sites in silver. We study small clusters of iron atoms as they grow to form FCC phase that is coherent with the silver lattice. The effects of the lattice relaxation and the ferromagnetic and antiferromagnetic couplings are also considered. When Fe atoms congregate around a central Fe atom in an FCC arrangement under ferromagnetic coupling, the local magnetic moment and the contact charge density at the central atom hardly change as the cluster builds up, whereas the hyperfine field increases asymptotically as the number of Fe nearest neighbors increases. Introduction of antiferromagnetic coupling has minor effect on the local magnetic moments and isomer shifts, however it produces large reduction in the hyperfine field. The lattice relaxation of the surrounding Fe atoms towards a BCC phase around a central Fe atom leads to reduction in the magnetic moment accompanied by increase in the magnetic hyperfine field.

  8. Optical properties of silver nanoparticles in glass

    Energy Technology Data Exchange (ETDEWEB)

    Matyssek, Christian [MLU Halle, Theoretical Physics Group, Halle (Germany); Max-Planck-Institute for Microstructure Physics, Halle (Germany); Stalmashonak, Andrei; Seifert, Gerhard [MLU Halle, Optics Group, Halle (Germany); Kiriyenko, Oleksiy; Hergert, Wolfram [MLU Halle, Theoretical Physics Group, Halle (Germany)

    2010-07-01

    The optical properties of silver nanoparticles (SNPs) in glass are studied. It is possible to transform initially spherical particles with the help of laser pulses with linear polarisation resulting in a prolate spheroidal shape. The transformation process stops for wavelengths shorter than the plasmon resonance of the SNPs. A model for the explanation of the SNP shape modification based on the electric field enhancement at the particle-glass-interface was developed. In order to confirm this model, the extinction efficiency and the electric field enhancement around the particles are calculated. Though for spherical particles Mie theory can be applied, and in principle it could be extended to spheroidal particles, no implementation of this method exists yet. Therefore the calculations for the spheroidal particles are done using the Finite-Element-Method (FEM). The results are in good agreement with experimental findings. While the calculations were done assuming the bulk permittivity for silver, the application of a non-local permittivity for small particles is discussed.

  9. Silver Matrix Composites - Structure and Properties

    Directory of Open Access Journals (Sweden)

    Wieczorek J.

    2016-03-01

    Full Text Available Phase compositions of composite materials determine their performance as well as physical and mechanical properties. Depending on the type of applied matrix and the kind, amount and morphology of the matrix reinforcement, it is possible to shape the material properties so that they meet specific operational requirements. In the paper, results of investigations on silver alloy matrix composites reinforced with ceramic particles are presented. The investigations enabled evaluation of hardness, tribological and mechanical properties as well as the structure of produced materials. The matrix of composite material was an alloy of silver and aluminium, magnesium and silicon. As the reinforcing phase, 20-60 μm ceramic particles (SiC, SiO2, Al2O3 and Cs were applied. The volume fraction of the reinforcing phase in the composites was 10%. The composites were produced using the liquid phase (casting technology, followed by plastic work (the KOBO method. The mechanical and tribological properties were analysed for plastic work-subjected composites. The mechanical properties were assessed based on a static tensile and hardness tests. The tribological properties were investigated under dry sliding conditions. The analysis of results led to determination of effects of the composite production technology on their performance. Moreover, a relationship between the type of reinforcing phase and the mechanical and tribological properties was established.

  10. Antibacterial activity of silver camphorimine coordination polymers.

    Science.gov (United States)

    Cardoso, João M S; Galvão, Adelino M; Guerreiro, Soraia I; Leitão, Jorge H; Suarez, Ana C; Carvalho, M Fernanda N N

    2016-04-28

    Five new silver camphorimine complexes of general formula [Ag(NO3)(Y)L] were synthesized and fully characterized using spectroscopic and analytical techniques. The structure of [Ag(NO3)(OC10H14NC6H4NC10H14O)] () was analyzed using single crystal X-ray diffraction, showing that it arranges as a coordination polymer formed by sequential Ag(NO3) units bridged by the bi-camphor ligand (). The antimicrobial properties of the new complexes were screened using the disk diffusion method and their Minimal Inhibitory Concentrations (MIC) were assessed against selected bacterial strains of the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli, Pseudomonas aeruginosa, and Burkholderia contaminans. The lowest MICs were observed for , with estimated values of 72, 20, 32 and 19 μg mL(-1) for S. aureus, E. coli, B. contaminans, and P. aeruginosa, respectively. In the case of S. aureus, similar MIC values were obtained for silver nitrate and compound . All five compounds were bactericidal when used in concentrations equal or above the MIC value, as found by enumerating the total colony forming units (CFUs) after incubation in their presence. PMID:27007331

  11. DNA-Protected Silver Clusters for Nanophotonics

    Directory of Open Access Journals (Sweden)

    Elisabeth Gwinn

    2015-02-01

    Full Text Available DNA-protected silver clusters (AgN-DNA possess unique fluorescence properties that depend on the specific DNA template that stabilizes the cluster. They exhibit peak emission wavelengths that range across the visible and near-IR spectrum. This wide color palette, combined with low toxicity, high fluorescence quantum yields of some clusters, low synthesis costs, small cluster sizes and compatibility with DNA are enabling many applications that employ AgN-DNA. Here we review what is known about the underlying composition and structure of AgN-DNA, and how these relate to the optical properties of these fascinating, hybrid biomolecule-metal cluster nanomaterials. We place AgN-DNA in the general context of ligand-stabilized metal clusters and compare their properties to those of other noble metal clusters stabilized by small molecule ligands. The methods used to isolate pure AgN-DNA for analysis of composition and for studies of solution and single-emitter optical properties are discussed. We give a brief overview of structurally sensitive chiroptical studies, both theoretical and experimental, and review experiments on bringing silver clusters of distinct size and color into nanoscale DNA assemblies. Progress towards using DNA scaffolds to assemble multi-cluster arrays is also reviewed.

  12. Assessing the Impacts of Climate and Land Use Change on Streamflow and Nutrient Loading in the Arroyo Colorado Watershed in Southern Texas

    Science.gov (United States)

    Osidele, O.; Sun, A.; Green, R.

    2011-12-01

    Based on results of the Second National Climate Assessment reported in 2009, the U.S. Global Change Research Program projects temperatures in southern Texas will increase 5 to 8° F by the end of the 21st century, with larger changes occurring under scenarios of higher greenhouse gas emissions. Temperature increases in summer are projected to be larger than in winter. Although drier conditions are expected in the region, sea-level rise, extreme rainfall events, and associated storm surges are projected to occur more frequently because of the likely increase in intensity of hurricanes and tropical storms in the Gulf of Mexico. The range of possible responses to climate change is attributable to a combination of characteristics at global, regional, and local scales. The risk of flooding and catastrophic infrastructure damage due to global climate phenomena has been incorporated into local climate adaptation plans for many low-lying areas and communities in the Gulf Coast region of southern Texas. However, because this region is dominated by irrigated agriculture and the population is projected to double by 2050, it is important to examine how climate change will affect water resources and environmental quality. The purpose of this study is to investigate the potential hydrologic and water quality impacts of projected climate change, land use change, and population change scenarios in the headwaters of the Arroyo Colorado. The results of this work will provide content for a web-based, collaborative geospatial decision support system being developed to support environmental management in the Arroyo Colorado Watershed. Presently, land use in the Arroyo Colorado Watershed is more than 50 percent agricultural and almost 25 percent residential with varying levels of urbanization. As a result, flow in the Arroyo Colorado is sustained primarily by discharge from municipal wastewater treatment facilities, irrigation return flows, and urban storm runoff. In this study

  13. The 2014 Greeley, Colorado Earthquakes: Science, Industry, Regulation, and Media

    Science.gov (United States)

    Yeck, W. L.; Sheehan, A. F.; Weingarten, M.; Nakai, J.; Ge, S.

    2014-12-01

    On June 1, 2014 (UTC) a magnitude 3.2 earthquake occurred east of the town of Greeley, Colorado. The earthquake was widely felt, with reports from Boulder and Golden, over 60 miles away from the epicenter. The location of the earthquake in a region long considered aseismic but now the locus of active oil and gas production prompted the question of whether this was a natural or induced earthquake. Several classic induced seismicity cases hail from Colorado, including the Rocky Mountain Arsenal earthquakes in the 1960s and the Paradox Valley earthquakes in western Colorado. In both cases the earthquakes were linked to wastewater injection. The Greeley earthquake epicenter was close to a Class II well that had been injecting waste fluid into the deepest sedimentary formation of the Denver Basin at rates as high as 350,000 barrels/month for less than a year. The closest seismometers to the June 1 event were more than 100 km away, necessitating deployment of a local seismic network for detailed study. IRIS provided six seismometers to the University of Colorado which were deployed starting within 3 days of the mainshock. Telemetry at one site allowed for real time monitoring of the ongoing seismic sequence. Local media interest was extremely high with speculation that the earthquake was linked to the oil and gas industry. The timetable of media demand for information provided some challenges given the time needed for data collection and analysis. We adopted a policy of open data and open communication with all interested parties, and made proactive attempts to provide information to industry and regulators. After 3 weeks of data collection and analysis, the proximity and timing of the mainshock and aftershocks to the C4A injection well, along with a sharp increase in seismicity culminating in an M 2.6 aftershock, led to a decision by the Colorado Oil and Gas Corporation Commission (COGCC) to recommend a temporary halt to injection at the C4A injection well. This was the

  14. Electroless silver coating of rod-like glass particles

    International Nuclear Information System (INIS)

    An electroless silver coating of rod-like glass particles was performed and silver glass composite powders were prepared to impart electrical conductivity to these non-conducting glass particles. The low density Ag-coated glass particles may be utilized for manufacturing conducting inorganic materials for electromagnetic interference (EMI) shielding applications and the techniques for controlling the uniform thickness of silver coating can be employed in preparation of biosensor materials. For the surface pretreatment, Sn sensitization was performed and the coating powders were characterized by scanning electron microscopy (SEM), focused ion beam microscopy (FIB), and atomic force microscopy (AFM) along with the surface resistant measurements. In particular, the use of FIB technique for determining directly the Ag-coating thickness was very effective on obtaining the optimum conditions for coating. The surface sensitization and initial silver loading for electroless silver coating could be found and the uniform and smooth silver-coated layer with thickness of 46 nm was prepared at 2 mol/l of Sn and 20% silver loading

  15. Toxicity of silver nanoparticles against bacteria, yeast, and algae

    Energy Technology Data Exchange (ETDEWEB)

    Dorobantu, Loredana S., E-mail: loredana@ualberta.ca; Fallone, Clara [University of Alberta, Department of Chemical and Materials Engineering (Canada); Noble, Adam J. [Trent University, Department of Biology (Canada); Veinot, Jonathan; Ma, Guibin [University of Alberta, Department of Chemistry (Canada); Goss, Greg G. [University of Alberta, Department of Biological Sciences (Canada); Burrell, Robert E. [University of Alberta, Department of Biomedical Engineering (Canada)

    2015-04-15

    The toxicity mechanism employed by silver nanoparticles against microorganisms has captivated scientists for nearly a decade and remains a debatable issue. The question most frequently asked is whether silver nanoparticles exert specific effects on microorganisms beyond the well-documented antimicrobial activity of Ag{sup +}. Here, we study the effects of citrate- (d = 17.5 ± 9.4 nm) and 11-mercaptoundecanoic acid (d = 38.8 ± 3.6 nm)-capped silver nanoparticles on microorganisms belonging to various genera. The antimicrobial effect of Ag{sup +} was distinguished from that of nanosilver by monitoring microbial growth in the presence and absence of nanoparticles and by careful comparison of the responses of equimolar silver nitrate solution. The results show that when using equimolar silver solutions, silver nitrate has higher toxic potential on all microorganisms than both nanoparticles tested. Furthermore, some microorganisms are more susceptible to silver than others and the choice of capping agent is relevant in the toxicity. Atomic force microscopy disclosed that AgNO{sub 3} had a destructive effect on algae. The antimicrobial activity of nanosilver could be exploited to prevent microbial colonization of medical devices and to determine the fate of nanoparticles in the environment.

  16. Biosynthesis, characterization, and antimicrobial applications of silver nanoparticles.

    Science.gov (United States)

    Singh, Priyanka; Kim, Yeon Ju; Singh, Hina; Wang, Chao; Hwang, Kyu Hyon; Farh, Mohamed El-Agamy; Yang, Deok Chun

    2015-01-01

    In the present study, the strain Brevibacterium frigoritolerans DC2 was explored for the efficient and extracellular synthesis of silver nanoparticles. These biosynthesized silver nanoparticles were characterized by ultraviolet-visible spectrophotometry, which detected the formation of silver nanoparticles in the reaction mixture and showed a maximum absorbance at 420 nm. In addition, field emission transmission electron microscopy revealed the spherical shape of the nanoparticles. The dynamic light scattering results indicated the average particle size of the product was 97 nm with a 0.191 polydispersity index. Furthermore, the product was analyzed by energy dispersive X-ray spectroscopy, X-ray diffraction, and elemental mapping, which displayed the presence of elemental silver in the product. Moreover, on a medical platform, the product was checked against pathogenic microorganisms including Vibrio parahaemolyticus, Salmonella enterica, Bacillus anthracis, Bacillus cereus, Escherichia coli, and Candida albicans. The nanoparticles demonstrated antimicrobial activity against all of these pathogenic microorganisms. Additionally, the silver nanoparticles were evaluated for their combined effects with the commercial antibiotics lincomycin, oleandomycin, vancomycin, novobiocin, penicillin G, and rifampicin against these pathogenic microorganisms. These results indicated that the combination of antibiotics with biosynthesized silver nanoparticles enhanced the antimicrobial effects of antibiotics. Therefore, the current study is a demonstration of an efficient biological synthesis of silver nanoparticles by B. frigoritolerans DC2 and its effect on the enhancement of the antimicrobial efficacy of well-known commercial antibiotics. PMID:25848272

  17. Bioconcentration factors (BCF) of silver in wild Agaricus campestris

    Energy Technology Data Exchange (ETDEWEB)

    Falandysz, J.; Danisiewicz, D. [Univ. of Gdansk (Poland)

    1995-07-01

    Silver is an element naturally occurring in small concentrations in different environmental sites. However, many anthropogenic sources of silver led to contamination of this element in soil surfaces, pastures, and coastal marine areas in different parts of the world. Estimates are that 40% of the 1.15x10{sup 4}t of silver produced annually worldwide, will escape into the environment. Due to municipal waste discharge and/or industrial effluents with high silver concentrations, 100 x above the background level have been reported in invertebrate species from polluted marine areas. The meta-stabile radioisotope, {sup 110m}Ag, is a main component of the liquid effluents from nuclear facilities under normal operating conditions. The presence of {sup 111}Ag and {sup 110m}Ag also has been widely found throughout Europe in the 1986 Chernobyl fallout. Silver ions are environmentally harmful. High toxic effects have been observed at low concentrations, especially in aquatic species. Species of lower fungi as well as the mushroom Agaricus bisporus are know to bioaccumulate high concentrations of silver when grown on an artificially enriched substrate. This study looks at the relationship between the silver content of soil and bioconcentration potential of wild Agaricus campestris from sites under different use and with different concentrations of heavy metals. 28 refs., 2 figs., 2 tabs.

  18. Antiglycating potential of gum arabic capped-silver nanoparticles.

    Science.gov (United States)

    Ashraf, Jalaluddin M; Ansari, Mohammad Azam; Choi, Inho; Khan, Haris M; Alzohairy, Mohammad A

    2014-09-01

    Advanced glycation end products are major contributors to the pathology of diabetes, Alzheimer's disease, and atherosclerosis; accordingly, identification of antiglycation compounds is attracting considerable interest. In the present study, the inhibitory effect of gum arabic capped-silver nanoparticles on advanced glycation end products formation was monitored by several biophysical techniques. Silver nanoparticles were characterized by ultraviolet-visible, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Bovine serum albumin and methylglyoxal mixtures incubated with increasing concentrations of silver nanoparticles showed significant reductions in advanced glycation end product formation that were confirmed by ultraviolet-visible, fluorescence spectrometry, and high-performance liquid chromatography techniques. High-performance liquid chromatography showed decreased adduct formation of glycated protein in the presence of silver nanoparticles. The structural changes induced by silver nanoparticles were further confirmed by circular dichroism and Fourier transform infrared spectroscopy. Strong inhibition of advanced glycation end product formation was observed in the presence of elevated silver nanoparticles. The results of this study suggest that silver nanoparticles are a potent antiglycating agent. PMID:25080376

  19. Adsorption of iodine by silver-impregnated hydrophobic adsorbent

    International Nuclear Information System (INIS)

    Hydrophobic adsorbents, which consist of porous styrene-divinylbenzene copolymer (SDB) impregnated with silver, were developed for the removal of iodine from the dissolver off-gas (DOG). The adsorption of iodine in a simulated off-gas including iodine, NOx and water vapor was examined by use of an adsorption column packed with the hydrophobic adsorbents. Silver impregnation methods using organic solutions were proposed. By use of dioxan and butylamine, which can swell the SDB easily, silver nitrate and metallic silver were uniformly distributed in the SDB particles. The breakthrough of iodine was not influenced by the presence of NOx and water vapor. For a macroporous SDB with the pore volume of 1.59 ml/g-SDB and the average pore diameter of 500A, impregnated with metallic silver at silver content of 28 wt%, a high adsorption capacity of 0.14g-I2/cm3-adsorbent was obtained, compared to that of a commercial adsorbent. AgNO3-impregnated silica gel. The impregnated silver was utilized about 91% for the iodine adsorption. (author)

  20. Pseudomonas deceptionensis DC5-mediated synthesis of extracellular silver nanoparticles.

    Science.gov (United States)

    Jo, Jae H; Singh, Priyanka; Kim, Yeon J; Wang, Chao; Mathiyalagan, Ramya; Jin, Chi-Gyu; Yang, Deok C

    2016-09-01

    The biological synthesis of metal nanoparticles is of great interest in the field of nanotechnology. The present work highlights the extracellular biological synthesis of silver nanoparticles using Pseudomonas deceptionensis DC5. The particles were synthesized in the culture supernatant within 48 h of incubation. Extracellular synthesis of silver nanoparticles in the culture supernatant was confirmed by ultraviolet-visible spectroscopy, which showed the absorption peak at 428 nm, and also under field emission transmission electron microscopy which displayed the spherical shape. In addition, the particles were characterized by X-ray diffraction spectroscopy, which corresponds to the crystalline nature of nanoparticles, and energy-dispersive X-ray analysis which exhibited the intense peak at 3 keV, resembling the silver nanoparticles. Further, the synthesized nanoparticles were examined by elemental mapping which displayed the dominance of the silver element in the synthesized product, and dynamic light scattering which showed the distribution of silver nanoparticles with respect to intensity, volume, and number of particles. Moreover, the silver nanoparticles have been found to be quite active in antimicrobial activity and biofilm inhibition activity against pathogenic microorganisms. Thus, the present work emphasized the prospect of using the P. deceptionensis DC5 to achieve the extracellular synthesis of silver nanoparticles in a facile and environmental manner. PMID:26232081