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Sample records for aurates

  1. Synthesis of tetra- and octa-aurated heteroaryl complexes towards probing aromatic indoliums.

    Science.gov (United States)

    Yuan, Jun; Sun, Tingting; He, Xin; An, Ke; Zhu, Jun; Zhao, Liang

    2016-01-01

    Polymetalated aromatic compounds are particularly challenging synthetic goals because of the limited thermodynamic stability of polyanionic species arising from strong electrostatic repulsion between adjacent carbanionic sites. Here we describe a facile synthesis of two polyaurated complexes including a tetra-aurated indole and an octa-aurated benzodipyrrole. The imido trinuclear gold(I) moiety exhibits nucleophilicity and undergoes an intramolecular attack on a gold(I)-activated ethynyl to generate polyanionic heteroaryl species. Their computed magnetic properties reveal the aromatic character in the five-membered ring. The incorporation of the aurated substituents at the nitrogen atom can convert non-aromaticity in the parent indolium into aromaticity in the aurated one because of hyperconjugation. Thus, the concept of hyperconjugative aromaticity is extended to heterocycles with transition metal substituents. More importantly, further analysis indicates that the aurated substituents can perform better than traditional main-group substituents. This work highlights the difference in aromaticity between polymetalated aryls and their organic prototypes. PMID:27186982

  2. Aria de pixel: riprodutibilità aurática digitale Ar de pixel: reprodutibilidade aurática digital Pixel air: digital auratic reprodutibility

    Directory of Open Access Journals (Sweden)

    Mássimo Canevacci

    2010-04-01

    . The challenge toward a university based not only on territorial Faculty is open. Different forms of communication are digitally mixing and syncretizing the Benjamin visions on aura and reproducibility. My final perspective is the Digital Auratic Reproducibility.

  3. Extending the satellite data record of tropospheric ozone profiles from Aura-TES to MetOp-IASI

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    H. Oetjen

    2014-07-01

    Full Text Available We apply the Tropospheric Emission Spectrometer (TES ozone retrieval algorithm to Infrared Atmospheric Sounding Instrument (IASI radiances and characterise the uncertainties and information content of the retrieved ozone profiles. This study focuses on mid-latitudes for the year 2008. We validate our results by comparing the IASI ozone profiles to ozone sondes. In the sonde comparisons, we find a positive bias in the IASI ozone profiles in the UTLS region of up to 14% on average. For the described cases, the degrees of freedom for signal are on average 3.2, 0.3, 0.8, and 0.9 for the columns 0 km–top of atmosphere, (0–6 km, (0–11 km, and (8–16 km, respectively. We find that our biases with respect to sondes and our degrees of freedom for signal for ozone are comparable to previously published results from other IASI ozone algorithms. In addition to evaluating biases, we validate the retrieval errors by comparing predicted errors to the sample covariance matrix of the IASI observations themselves. For the predicted vs. empirical error comparison, we find that these errors are consistent and that the measurement noise and the interference of temperature and water vapour on the retrieval together mostly explain the empirically derived random errors. In general, the precision of the IASI ozone profiles is better than 20%.

  4. Regioselectivities in alkyne activation: synthesis of 2-(bicyclo[3.1.0]hexan-1-yl)furan derivatives by Au-catalyzed cyclization and cyclopropanation.

    Science.gov (United States)

    Oh, Chang Ho; Lee, Su Jin; Lee, Ji Ho; Na, Yoon Jung

    2008-11-30

    2-Alkynyl-1-cycloalkenecarbaldehydes, in the presence of gold catalysts, undergo aurative cyclization via the 5-exo-dig mode to form Au-carbene intermediates which react with a double bond to form the corresponding cyclopropanes. PMID:19009084

  5. Four steps in the history of museum technologies and visitors' digital participation

    DEFF Research Database (Denmark)

    Christensen, Jørgen Riber

    2011-01-01

    The hypothesis of this article is that the authentic and auratic exhibited objects in museums enter into a dialogue with surrounding paratexts. The paratexts anchor and change the meaning of the exhibited object in the museum context. Recent years have indicated a tendency for museum paratexts to...... the historical context of the object and towards the contemporary world of the visitor. The article connects this change in cultural discourse with Karin Sander's archaeological imagination and in a wider sense with the concept of negotiation from new historicism....

  6. La obra de arte en la época de la retuiteabilidad

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    Paulo Antonio Gatica Cote

    2014-11-01

    Full Text Available In this paper I will study the artistic status and circulation of cultural products in the social network Twitter. To this end, I will take the ideas of Walter Benjamin on the loss of “aura” and the José Luis Brea’s approaches about the electronic cultural capitalism, a new stage of culture characterized by the passage of an auratic monumental logic to an “era of electronic distribution” and its new possibilities of distribution and access.

  7. Engineering of poly(ethylene glycol) chain-tethered surfaces to obtain high-performance bionanoparticles

    OpenAIRE

    Yukio Nagasaki

    2010-01-01

    A poly(ethylene glycol)-b-poly[2-(N,N-dimethylamino)ethyl methacrylate] block copolymer possessing a reactive acetal group at the end of the poly(ethylene glycol) (PEG) chain, that is, acetal-PEG-b-PAMA, was synthesized by a proprietary polymerization technique. Gold nanoparticles (GNPs) were prepared using the thus-synthesized acetal-PEG-b-PAMA block copolymer. The PEG-b-PAMA not only acted as a reducing agent of aurate ions but also attached to the nanoparticle surface. The GNPs obtained ha...

  8. Rapid colorimetric sensing of tetracycline antibiotics with in situ growth of gold nanoparticles

    International Nuclear Information System (INIS)

    Highlights: • Tetracyclines directly reduce aurate into gold nanoparticles. • Gold nanoparticles showed characteristic plamson absorbance at 526 nm. • Quantitative detection of tetracyclines with the colorimetric assay. • Tetracyclines spiked urine samples can be detected with the assay. - Abstract: A colorimetric assay utilizing the formation of gold nanoparticles was developed to detect tetracycline antibiotics in fluidic samples. Tetracycline antibiotics showed the capability of directly reducing aurate salts into atomic gold which form gold nanoparticles spontaneously under proper conditions. The resulted gold nanoparticles showed characteristic plasmon absorbance at 526 nm, which can be visualized by naked eyes or with a spectrophotometer. UV–vis absorbance of the resulted gold nanoparticles is correlated directly with the concentrations of tetracycline antibiotics in the solution, allowing for quantitative colorimetric detection of tetracycline antibiotics. Reaction conditions, such as pH, temperature, reaction time, and ionic strength were optimized. Sensitivity of the colorimetric assay can be enhanced by the addition of gold nanoparticle seeds, a LOD as low as 20 ng mL−1 can be achieved with the help of seed particles. The colorimetric assay showed minimum interference from ethanol, methanol, urea, glucose, and other antibiotics such as sulfonamides, amino glycosides etc. Validity of the method was also evaluated on urine samples spiked with tetracycline antibiotics. The method provides a broad spectrum detection method for rapid and sensitive detection of reductive substances such as tetracycline antibiotics in liquid and biological samples

  9. Rapid colorimetric sensing of tetracycline antibiotics with in situ growth of gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Li, E-mail: lishen97@163.com [Logistics School, Beijing Wuzi University, Beijing 101149 (China); Chen, Jing; Li, Na [Logistics School, Beijing Wuzi University, Beijing 101149 (China); He, Pingli [State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing 100094 (China); Li, Zhen [State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193 (China)

    2014-08-11

    Highlights: • Tetracyclines directly reduce aurate into gold nanoparticles. • Gold nanoparticles showed characteristic plamson absorbance at 526 nm. • Quantitative detection of tetracyclines with the colorimetric assay. • Tetracyclines spiked urine samples can be detected with the assay. - Abstract: A colorimetric assay utilizing the formation of gold nanoparticles was developed to detect tetracycline antibiotics in fluidic samples. Tetracycline antibiotics showed the capability of directly reducing aurate salts into atomic gold which form gold nanoparticles spontaneously under proper conditions. The resulted gold nanoparticles showed characteristic plasmon absorbance at 526 nm, which can be visualized by naked eyes or with a spectrophotometer. UV–vis absorbance of the resulted gold nanoparticles is correlated directly with the concentrations of tetracycline antibiotics in the solution, allowing for quantitative colorimetric detection of tetracycline antibiotics. Reaction conditions, such as pH, temperature, reaction time, and ionic strength were optimized. Sensitivity of the colorimetric assay can be enhanced by the addition of gold nanoparticle seeds, a LOD as low as 20 ng mL{sup −1} can be achieved with the help of seed particles. The colorimetric assay showed minimum interference from ethanol, methanol, urea, glucose, and other antibiotics such as sulfonamides, amino glycosides etc. Validity of the method was also evaluated on urine samples spiked with tetracycline antibiotics. The method provides a broad spectrum detection method for rapid and sensitive detection of reductive substances such as tetracycline antibiotics in liquid and biological samples.

  10. Optimizing growth conditions for electroless deposition of Au films on Si(111) substrates

    Indian Academy of Sciences (India)

    Bhuvana; G U Kulkarni

    2006-10-01

    Electroless deposition of Au films on Si(111) substrates from fluorinated-aurate plating solutions has been carried out at varying concentrations, deposition durations as well as bath temperatures, and the resulting films were characterized by X-ray diffraction, optical profilometry, atomic force microscopy and scanning electron microscopy. Depositions carried out with dilute plating solutions (< 0.1 mM) at 28°C for 30 min produce epitaxial films exhibiting a prominent Au(111) peak in the diffraction patterns, while higher concentrations or temperatures, or longer durations yield polycrystalline films. In both epitaxial and polycrystalline growth regimes, the film thickness increases linearly with time, however, in the latter case, at a rate an order of magnitude higher. Interestingly, the surface roughness measured using atomic force microscopy shows a similar trend. On subjecting to annealing at 250°C, the roughness of the film decreases gradually. Addition of poly (vinylpyrrolidone) to the plating solution is shown to produce a X-ray amorphous film with nanoparticulates capped with the polymer as evidenced by the core-level photoelectron spectrum. Nanoindentation using AFM has shown the hardness of the films to be much higher (∼ 2.19 GPa) than the bulk value.

  11. TECHNOLOGY FOR THE PREPARATION OF LIVESTOCK WASTEWATER FOR IRRIGATION OF AGRICULTURAL CROPS

    Directory of Open Access Journals (Sweden)

    Domashenko Y. E.

    2015-02-01

    Full Text Available In the article the authors propose various techniques for the preparation of livestock waste for agricultural use, particularly for irrigation. We have considered resource-saving environmentally safe technology for processing livestock waste pig farms based on the use of the reagent preparation phosphogypsum – residuals of phosphoric acid and fertilizers. The technology was tested and endorsed at the operating company LLC "Aksai field" of the Rostov region. Also based on this technology, we have offered the following technical solution: livestock wastewater is exposed to the vortex field with movable ferromagnetic particles, which contributes to more complete disinfecting effect. Further improvement of the technological scheme of training for livestock waste allowed to get more modern technical solution, including sewage treatment acidifying reagent is a suspension of phosphogypsum and slightly basic by oxychloride brand Aqua-Aurat. With the aim of reducing the cost and simplifying the technology of training we offered using a reagent, obtained from natural raw materials - silica-coagulant on the basis of nepheline instead of the low-base oxychloride brand Aqua-AuraTM. Aluminosilicate coagulant on the basis of nepheline may be used at high values of COD up to 2000 mg O/l and TBOD to 1500 mg O/l, which is a limitation for the use of such coagulants in the preparation of livestock wastewater pig farms. All the proposed technologies are based on the positions of resource and energy efficiency and environmental safety

  12. Engineering of poly(ethylene glycol) chain-tethered surfaces to obtain high-performance bionanoparticles

    International Nuclear Information System (INIS)

    A poly(ethylene glycol)-b-poly[2-(N,N-dimethylamino)ethyl methacrylate] block copolymer possessing a reactive acetal group at the end of the poly(ethylene glycol) (PEG) chain, that is, acetal-PEG-b-PAMA, was synthesized by a proprietary polymerization technique. Gold nanoparticles (GNPs) were prepared using the thus-synthesized acetal-PEG-b-PAMA block copolymer. The PEG-b-PAMA not only acted as a reducing agent of aurate ions but also attached to the nanoparticle surface. The GNPs obtained had controlled sizes and narrow size distributions. They also showed high dispersion stability owing to the presence of PEG tethering chains on the surface. The same strategy should also be applicable to the fabrication of semiconductor quantum dots and inorganic porous nanoparticles. The preparation of nanoparticles in situ, i.e. in the presence of acetal-PEG-b-PAMA, gave the most densely packed polymer layer on the nanoparticle surface; this was not observed when coating preformed nanoparticles. PEG/polyamine block copolymer was more functional on the metal surface than PEG/polyamine graft copolymer, as confirmed by angle-dependent x-ray photoelectron spectroscopy. We successfully solubilized the C60 fullerene into aqueous media using acetal-PEG-b-PAMA. A C60/acetal-PEG-b-PAMA complex with a size below 5 nm was obtained by dialysis. The preparation and characterization of these materials are described in this review. (topical review)

  13. Petyarre and Moffat: 'Looking from the Sky'

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    Linnell Secomb

    2013-08-01

    Full Text Available Moffatt’s Up in the Sky series draws attention to the relation between sky and earth, through the content and camera angles of the images. Similarly, Kathleen Petyarre’s Central Desert acrylic dot painting evokes this relation representing country and Dreaming from a celestial perspective—as she says ‘looking from the sky’. Yet here any association between these artists seems to end with the urban artist refusing to engage Aboriginal tradition and the desert artist focused on Dreaming, country and heritage. However, a further connection between these disparate works may also be discerned as each, in differing ways, transforms our conventional perceptions of space and time. Reading these images in relation to Walter Benjamin’s concepts of the auratic and of messianic time, I suggest that each restructures dimension and duration putting in question the (postmodern calibrations of our space/time experience. This paper stages an engagement between these artists’ works and Benjamin’s concepts exploring the variations and modifications of the spatial and the temporal that hybrid cross-cultural exchanges require and facilitate.

  14. Engineering of poly(ethylene glycol chain-tethered surfaces to obtain high-performance bionanoparticles

    Directory of Open Access Journals (Sweden)

    Yukio Nagasaki

    2010-01-01

    Full Text Available A poly(ethylene glycol-b-poly[2-(N,N-dimethylaminoethyl methacrylate] block copolymer possessing a reactive acetal group at the end of the poly(ethylene glycol (PEG chain, that is, acetal-PEG-b-PAMA, was synthesized by a proprietary polymerization technique. Gold nanoparticles (GNPs were prepared using the thus-synthesized acetal-PEG-b-PAMA block copolymer. The PEG-b-PAMA not only acted as a reducing agent of aurate ions but also attached to the nanoparticle surface. The GNPs obtained had controlled sizes and narrow size distributions. They also showed high dispersion stability owing to the presence of PEG tethering chains on the surface. The same strategy should also be applicable to the fabrication of semiconductor quantum dots and inorganic porous nanoparticles. The preparation of nanoparticles in situ, i.e. in the presence of acetal-PEG-b-PAMA, gave the most densely packed polymer layer on the nanoparticle surface; this was not observed when coating preformed nanoparticles. PEG/polyamine block copolymer was more functional on the metal surface than PEG/polyamine graft copolymer, as confirmed by angle-dependent x-ray photoelectron spectroscopy. We successfully solubilized the C60 fullerene into aqueous media using acetal-PEG-b-PAMA. A C60/acetal-PEG-b-PAMA complex with a size below 5 nm was obtained by dialysis. The preparation and characterization of these materials are described in this review.

  15. Algunas reflexiones desde la acuarela de Mario Conde

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    Pamela Romano

    2012-11-01

    Full Text Available This brief reflection on the work of Mario Conde starts paying attention to the special relationship the artist has with the watercolor technique, deploying from that relationship a copy-based ethics. From that materiality Conde builds his response to the postmodern moment in which art in general, and particularly Bolivian art, is been developed given its current social conditions. The ethics of the copy is explored especially in two of his works: "Exterminator Angel" where  copying addresses colonial issues that return to question and challenge the very notion of homeland, and "Drunk with power (Géricault in Los Andes" where the copy,  adapted to Andean latitudes, exudes a desire to restore the sacred and  auratic character of artwork as well as of the Andean imagery.Esta breve reflexión sobre la obra de Mario Conde se inicia poniendo atención en la relación particular que tiene el pintor con la técnica de la acuarela, desplegando desde esa relación una ética basada en la copia. Desde esa materialidad Conde concretiza su respuesta al momento posmoderno en que se desarrolla el arte en general, y el boliviano en particular dadas sus condiciones sociales actuales. La ética de la copia es explorada especialmente en dos de sus obras: “Ángel exterminador” donde la copia aborda temáticas coloniales que retornan para poner en cuestión y entredicho la noción de patria, y “Ebrios de poder (Géricault en Los Andes” donde la copia adaptada a latitudes andinas destila un deseo de restablecer el carácter sagrado y aurático de la obra de arte como del imaginario andino.

  16. Apparence et jeu, valeur cultuelle et valeur d’exposition chez Walter Benjamin

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    Anne Boissière

    2007-05-01

    Full Text Available À travers le couple valeur cultuelle/valeur d’exposition présent dans son essai sur la reproductibilité technique, Walter Benjamin introduit une conception historique et dialectique de l’apparence. La valeur contemplative que l’esthétique philosophique accorde à la perception esthétique est relativisée au bénéfice d’une conception pratique de la perception, anciennement tangible dans l’activité magique mais possiblement redéployée avec la photographie et le cinéma. Ce texte veut rendre justice à la dimension pratique et politique qui sous-tend la réflexion de Benjamin sur la reproduction technique : la perception auratique est envisagée comme un moment historique indissociablement lié au développement de la technique.By way of the couple cult-value/exhibition-value as present in his essay on artwork and technical reproduction, Walter Benjamin introduces a historical as well as dialectical theory of appearance. The contemplative attitude often identified with aesthetic perception in philosophical aesthetics is thus deconstructed in favour of a practical mode of perception, formely tangible in magical activity but possibly recovered with photography and cinema. The present article proposes to do justice to the practical and political thought that buttresses Benjamin’s reflection on technical reproducibility: auratic perception is envisaged as a historical moment ineluctably linked to the development of technology.

  17. Isolation of 1,4-Li(2)-C(6)H(4) and its reaction with [(Ph(3)P)AuCl].

    Science.gov (United States)

    Flower, Kevin R; McGown, A T; Miles, Philip J; Pritchard, Robin G; Warren, John E

    2010-04-14

    The difficulty in generating 1,4-Li2-C6H4 utilising the lithium halogen exchange reaction on 1,4-Br2-C6H4, 1,4-I2-C6H4 and 1-Br-4-I-C6H4 is revisited and only on treatment of 1,4-I2-C6H4 with 2 molar equivalents of n-BuLi can 1,4-Li2-C6H4 1 be isolated in excellent yield. Treatment of 1 with two equivalents of [ClAu(PPh3)] gives [1,4-(Ph3PAu)2-C6H4] 2a in excellent yield. Subsequent treatment of 2a with 2.5 molar equivalents of PPh2Me, PPhMe2 or PMe3 affords the PPh3 substituted compounds [1,4-(LAu)2-C6H4] (L = PPh2Me 2b, PPhMe2 2c, PMe3 2d) in essentially quantitative yields. On treatment of 1,4-Br2-C6H4 or 1-Br-4-I-C6H4 with 2 molar equivalents of n-BuLi only mono-lithiation takes place to give 1-Br-4-Li-C6H4 3 as shown through the isolation of essentially 1:1 molar equivalents of Ph2PC6H4-4-Br and Ph2PBu on treatment with 2 molar equivalents of ClPPh2. Treatment of 3, prepared by lithium/iodine exchange on 1-Br-4-I-C6H4, with [ClAu(PPh3)] affords [(Ph3P)Au(C6H4-4-Br)] 4 as expected and in addition [(Ph3P)Au(n-Bu)(C6H4-4-Br)2] 5, indicating the straightforward chloride/aryl exchange at gold may proceed in competition with oxidative addition of the n-BuI, generated in the initial lithium/iodine exchange reaction, to some aurate complex Li[Au(C6H4-4-Br)2] 6 formed in situ followed by reductive elimination of Br-C6H4-4-n-Bu in a manner that mimics lithium diorganocuprate chemistry. All of the gold-containing compounds have been spectroscopically characterised by 1H and 31P-{1H} NMR and in addition compounds 2a-d and 5 by single crystal X-ray diffraction studies. The solid state structures observed for 2a-d are dictated by non-conventional hydrogen bonding and the packing requirements of the phosphine ligands. For 2a and 2b there is no close Au...Au approach, however for 2c and 2d the reduction in the number of phenyl rings allows the formation of Au...Au contacts. For 2c and 2d the extended structures appear to be helical chains with Au...Au contact parameters of 3