Search results for "gold"
showing 10 items of 1320 documents
PRIME NUMBERS, QUANTUM FIELD THEORY AND THE GOLDBACH CONJECTURE
2012
Motivated by the Goldbach conjecture in Number Theory and the abelian bosonization mechanism on a cylindrical two-dimensional spacetime we study the reconstruction of a real scalar field as a product of two real fermion (so-called \textit{prime}) fields whose Fourier expansion exclusively contains prime modes. We undertake the canonical quantization of such prime fields and construct the corresponding Fock space by introducing creation operators $b_{p}^{\dag}$ --labeled by prime numbers $p$-- acting on the vacuum. The analysis of our model, based on the standard rules of quantum field theory and the assumption of the Riemann hypothesis, allow us to prove that the theory is not renormalizabl…
GOLD MINING AND JULA INFLUENCE IN PRECOLONIAL SOUTHERN BURKINA FASO
2007
ABSTRACTThe ‘Lobi’ region in what is today southern Burkina Faso is frequently mentioned in historical accounts of gold mining in West Africa. However, little is known about the actual location of the gold mines or about the way gold mining and trade were organized in precolonial times. This article points out that some previous hypotheses about precolonial gold mining, trade and the sociopolitical organization of this region are flawed, partly because ‘Lobi’, as the name for both the region and its inhabitants, is misleading. In fact, the references to ‘Lobi’ merge two distinct gold-producing zones along the Mouhoun river, about 200 km from each other. The present-day populations of southe…
Some data on the transmission of the lives of saints between the Middle Ages and the modern era in the Crown of Aragon
2019
En l’edat mitjana les vides de sants eren models a seguir, exemples en els sermonaris i en els textos didacticodoctrinals. La popularitat d’aquestes vides es reflecteix en les arts plàstiques i visuals, en la literatura i en la cultura popular. A través de l’exemple de la transmissió escrita de tres vides de sants incloses en la traducció catalana de la Legenda aurea, presentem en aquest treball una aproximació a la manera en què es difonien aquelles vides, que circulaven de manera individual o integrades en compilacions i que podien oferir versions diferents en cada cas. La repercussió d’aquelles vides perviu en l’època moderna, que les recull en forma de composicions en vers, obres de tea…
The Lady Half-Devoured by a Dragon and the Iconography of Saint Margaret of Antioch : Interpreting an Anonymous Invención in the Cancionero general (…
2018
Following in the footsteps of Ian Macpherson, I offer an interpretation of an anonymous invención found in the Cancionero general (11CG-517) and the British Library Cancionero (LB1-251). I maintain that the image displayed by the jouster was inspired by the iconography of the virgin-martyr Saint Margaret of Antioch, and I propose a theory about the identity of the lady addressed and, with less certainty, about the identity of the jouster and the occasion when the invención was displayed, using Pinar’s Juego trobado as a tool of research and invoking a passage on the sinfulness of the fashion among ladies and damsels for wearing hooped petticoats in a treatise by Hernando de Talavera.
A Tale of Two Re-branded Cities: Riga, Latvia and Aarhus, Denmark
2016
Abstract This study shows how Riga and Arhus identified, formulated and communicated city re-branding. Our analysis concentrates on resident responses to city re-branding and how such responses could force the municipalities to withdraw their re-branding. A city loses its identity if it is globalized. In the Riga and Aarhus cases, the municipalities tried to find a global voice, which contradicted local traditions; and in both cases, the redefinition of city image took place top-down and not bottom-up. The two cases may not prove to be a golden rule, but should be a warning against rash city re-branding decisions made by municipalities.
Gold-Catalyzed Intramolecular Hydroamination of o-Alkynylbenzyl Carbamates: A Route to Chiral Fluorinated Isoindoline and Isoquinoline Derivatives
2013
Enantiomerically pure fluorinated isoindoline and dihydroisoquinoline scaffolds have been prepared through a diastereoselective addition of fluorinated nucleophiles to Ellman’s N-(tert-butanesulfinyl)imines followed by a sequence of Sonogashira cross-coupling/gold(I)-catalyzed cycloisomerization of the corresponding carbamate. A more favored 5-exo-dig mechanism was observed mainly due to an electronic effect of the fluorinated group.
Au/TiO2-CeO2 Catalysts for Photocatalytic Water Splitting and VOCs Oxidation Reactions
2016
Photocatalytic water splitting for H2 production and photocatalytic oxidation of 2-propanol, an example of volatile organic compounds, were investigated over TiO2 catalysts loaded with gold and/or ceria. In the water splitting reaction the presence of gold only slightly affected the performance of TiO2 whereas the presence of CeO2 had a more remarkable positive effect. In the 2-propanol oxidation Au/TiO2 was the most active sample in terms of alcohol conversion whereas Au/TiO2-CeO2 exhibited the highest CO2 yield. On the basis of characterization experiments (X-Ray Diffraction (XRD), Energy Dispersive X-ray Analysis EDX, surface area measurements, Diffuse Reflectance Spectroscopy (DRS) and …
Near-Infrared Light Responsive Folate Targeted Gold Nanorods for Combined Photothermal-Chemotherapy of Osteosarcoma.
2017
Folate-targeted gold nanorods (GNRs) are proposed as selective theranostic agents for osteosarcoma treatment. An amphiphilic polysaccharide based graft-copolymer (INU-LA-PEG-FA) and an amino derivative of the α,β-poly(N-2-hydroxyethyl)-d,l-aspartamide functionalized with folic acid (PHEA-EDA-FA), have been synthesized to act as coating agents for GNRs. The obtained polymer-coated GNRs were characterized in terms of size, shape, zeta potential, chemical composition, and aqueous stability. They protected the anticancer drug nutlin-3 and were able to deliver it efficiently in different physiological media. The ability of the proposed systems to selectively kill tumor cells was tested on U2OS…
Exploring the atomic structure of 1.8 nm monolayer-protected gold clusters with aberration-corrected STEM
2017
Abstract Monolayer-protected (MP) Au clusters present attractive quantum systems with a range of potential applications e.g. in catalysis. Knowledge of the atomic structure is needed to obtain a full understanding of their intriguing physical and chemical properties. Here we employed aberration-corrected scanning transmission electron microscopy (ac-STEM), combined with multislice simulations, to make a round-robin investigation of the atomic structure of chemically synthesised clusters with nominal composition Au 144 (SCH 2 CH 2 Ph) 60 provided by two different research groups. The MP Au clusters were “weighed” by the atom counting method, based on their integrated intensities in the high …
Polymer/metal hybrid multilayers modified Schottky devices
2013
Insulating, polymethylmethacrylate (PMMA), and semiconducting, poly(3-hexylthiophene) (P3HT), nanometer thick polymers/Au nanoparticles based hybrid multilayers (HyMLs) were fabricated on p-Si single-crystal substrate. An iterative method, which involves, respectively, spin-coating (PMMA and P3HT deposition) and sputtering (Au nanoparticles deposition) techniques to prepare Au/HyMLs/p-Si Schottky device, was used. The barrier height and the ideality factor of the Au/HyMLs/p-Si Schottky devices were investigated by current-voltage measurements in the thickness range of 1-5 bilayers. It was observed that the barrier height of such hybrid layered systems can be tuned as a function of bilayers …