X-ray absorption study of the ferromagnetic Cu moment at the YBa_(2)Cu_(3)O_(7)/La_(2/3)Ca_(1/3)MnO_(3) interface and variation of its exchange interaction with the Mn moment

With x-ray absorption spectroscopy and polarized neutron reflectometry we studied how the magnetic proximity effect at the interface between the cuprate high-TC superconductor YBa_(2)Cu_(3)O_(7) (YBCO) and the ferromagnet La_(2/3)Ca_(1/3)MnO_(3) (LCMO) is related to the electronic and magnetic properties of the LCMO layers. In particular, we explored how the magnitude of the ferromagnetic Cu moment on the YBCO side depends on the strength of the antiferromagnetic (AF) exchange coupling with the Mn moment on the LCMO side. We found that the Cu moment remains sizable if the AF coupling with the Mn moments is strongly reduced or even entirely suppressed. The ferromagnetic order of the Cu moments thus seems to be intrinsic to the interfacial CuO_(2) planes and related to a weakly ferromagnetic intraplanar exchange interaction. The latter is discussed in terms of the partial occupation of the Cu 3d_(3z^(2)−r^(2)) orbitals, which occurs in the context of the so-called orbital reconstruction of the interfacial Cu ions.

Sistemas y Procesos en Publicidad y Relaciones Públicas. Tema 3, parte 1 (curso 2011-2012)

Resumen del Tema 3 (parte 1), para los grupos 1,2,3 y 4.

Screen-printed electrode-based electrochemical detector coupled with in-situ ionic-liquid-assisted dispersive liquid–liquid microextraction for determination of 2,4,6-trinitrotoluene

A novel method is reported, whereby screen-printed electrodes (SPELs) are combined with dispersive liquid–liquid microextraction. In-situ ionic liquid (IL) formation was used as an extractant phase in the microextraction technique and proved to be a simple, fast and inexpensive analytical method. This approach uses miniaturized systems both in sample preparation and in the detection stage, helping to develop environmentally friendly analytical methods and portable devices to enable rapid and onsite measurement. The microextraction method is based on a simple metathesis reaction, in which a water-immiscible IL (1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, [Hmim][NTf2]) is formed from a water-miscible IL (1-hexyl-3-methylimidazolium chloride, [Hmim][Cl]) and an ion-exchange reagent (lithium bis[(trifluoromethyl)sulfonyl]imide, LiNTf2) in sample solutions. The explosive 2,4,6-trinitrotoluene (TNT) was used as a model analyte to develop the method. The electrochemical behavior of TNT in [Hmim][NTf2] has been studied in SPELs. The extraction method was first optimized by use of a two-step multivariate optimization strategy, using Plackett–Burman and central composite designs. The method was then evaluated under optimum conditions and a good level of linearity was obtained, with a correlation coefficient of 0.9990. Limits of detection and quantification were 7 μg L−1 and 9 μg L−1, respectively. The repeatability of the proposed method was evaluated at two different spiking levels (20 and 50 μg L−1), and coefficients of variation of 7 % and 5 % (n = 5) were obtained. Tap water and industrial wastewater were selected as real-world water samples to assess the applicability of the method.

1,2-Functionalized Imidazoles as Palladium Ligands: An Efficient and Robust Catalytic System for the Fluorine-Free Hiyama Reaction

A variety of hydroxy- and amino-functionalized imidazoles were prepared from 1-methyl- and 1-(diethoxymethyl)imidazole by means of isoprene-mediated lithiation followed by reaction with an electrophile. These compounds in combination with palladium acetate were screened as catalyst systems for the Hiyama reaction under fluorine-free conditions using microwave irradiation. The systematic study of the catalytic system showed 1-methyl-2-aminoalkylimidazole derivative L1 to be the best ligand, which was employed under solvent-free conditions with a 1:2 Pd/ligand ratio and TBAB (20 mol-%) as additive. The study has revealed an interaction between the Pd/ligand ratio and the amount of TBAB. The established catalytic system presented a certain degree of robustness, and it has been successfully employed in the coupling of a range of aryl bromides and chlorides with different aryl siloxanes. Furthermore, both reagents were employed in an equimolecular amount, without an excess of organosilane.

Enantioselective addition of aryl ketones and acetone to nitroalkenes organocatalyzed by carbamate-monoprotected cyclohexa-1,2-diamines

Enantiomerically pure carbamate-monoprotected trans-cyclohexane-1,2-diamines are used as chiral organocatalysts for the addition of aryl ketones and acetone to nitroalkenes to give enantioenriched β-substituted γ-nitroketones. The reaction was performed in the presence of 3,4-dimethoxybenzoic acid as an additive, in chloroform as the solvent at room temperature, achieving enantioselectivities up to 96%. Theoretical calculations are used to justify the observed sense of the stereoinduction.

Berlin, Germany, 1748 (Image 1 of 4) (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Plan de la ville de Berlin : levé et dessiné par ordre et privilege privatif du Roy sous la direction du Marchall Comte de Schmettau, par Hildner approuvé par l'Academie Royale de Science â Berlin ; gravé sous la direction de G.F. Schmidt Graveur du Roy. It was published by l'Academie Royale de Science â Berlin in 1748. Scale [ca. 1:6,500]. Covers Berlin, Germany. This layer is image 1 of 4 total images of the four sheet source map, representing the northeast portion of the map. Map in French and German.The image inside the map neatline is georeferenced to the surface of the earth and fit to the Deutsches Hauptdreiecksnetz (DHDN) 3-degree Gauss-Kruger Zone 4 coordinate system. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as roads, drainage, built-up areas and selected buildings, fortification, parks, cemeteries, ground cover, and more. Relief shown by hachures. Includes also view and inset engravings: Prospect du Stadt Berlin von Süden gegen Norden -- 1. Prospect des grossen Platzes von Opera Hausse 2. der Cathol. Kirche St. Hedwig 3. und einer Seite des Marggraff Henrich. Pallais -- Prospect der Neuen Schloss u Dohm Kirche -- Prospect des Neuen Königl. Printz Heinrich. Pallais den Opern Hausse gegen über.This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of originators, ground condition dates, scales, and map purposes.

County Armàgh, Northern Ireland, United Kingdom, 1760 (Image 1 of 4) (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: A topographical map of the county of Armagh to which is anex'd the plans of Newry and Armagh, by John Rocque = Carte topographique de la Province d'Armagh où se trouve les plans des villes d'Armagh et de Newry, par Jean Rocque. It was published by J. Rocque in 1760. Scale [ca. 1:41,000]. This layer is image 1 of 4 total images of the four sheet source map, representing the southeast portion of the map. Covers County Armàgh, Northern Ireland. Map in English and French. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Irish Grid (Transverse Mercator 1965 (TM-65)) coordinate system. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as roads, drainage, built-up areas and selected buildings, selected names of landowners, ground cover, and more. Relief shown by hachures and pictorially. Includes 2 insets: "A Plan of the Town of Newry" -- "A Plan of the City of Armagh".This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of originators, ground condition dates, scales, and map purposes.

Bristol, England, 1743 (Image 1 of 4) (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Plan of the city of Bristol, survey'd and drawn by John Rocque ; engrav'd by John Pine, 1742. It was published by Benjamin Hickey, Bookseller in 1743. Scale [ca. 1:2,074]. This layer is image 1 of 4 total images of the four sheet source map, representing the northwest portion of the map. The image inside the map neatline is georeferenced to the surface of the earth and fit to the 'British National Grid' coordinate system. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as roads, drainage, built-up areas and selected buildings and industries, selected landowner names, churches, cemeteries, parks, docks, wharves, ground cover, and more. Relief shown by hachures. Includes also a brief description of the city and the elevation of the south front of the Exchange building.This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of originators, ground condition dates, scales, and map purposes.

Central America & Caribbean Region, 1803 (Image 1 of 4) (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Chart of the West Indies and Spanish Dominions in North America, by A. Arrowsmith ; Jones, Smith & Co., sc. Beaufort Buildgs., Strand. It was published June 1st, 1803, by A. Arrowsmith, No. 24 Rathbone Place. Scale [ca. 1:2,775,525]. This layer is image 1 of 4 total images of the four sheet source map, representing the northeast portion of the map. Covers primarily Central America and the Caribbean region.The image inside the map neatline is georeferenced to the surface of the earth and fit to the World Miller Cylindrical projected coordinate system. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as drainage, cities and other human settlements, territorial boundaries, shoreline features, roads, mines, and more. Relief shown by hachures, depths shown by soundings. Includes notes.This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of originators, ground condition dates, scales, and map purposes.

Grand Manan Island, New Brunswick, Passamaquoddy Bay, Maine and Saint Croix River, Nautical Chart, 1781 (Image 1 of 4) (Raster Image)

This layer is a georeferenced raster image of the untitled, historic nautical chart: [A chart of the Island of Grand Manan, Passamaquody Bay & River]. The map is [sheet 47] from the Atlantic Neptune atlas Vol. 3 : Charts of the coast and harbors of New England, from surveys taken by Samuel Holland and published by J.F.W. Des Barres, 1781. Scale [ca. 1:50,000]. This layer is image 1 of 4 total images of the four sheet source map, representing the northeast portion of the map. Covers coastline from Blacks Harbour to Haggertys Cove, New Brunswick, Canada and portion of Bay of Fundy. The image is georeferenced to the surface of the earth and fit to the 'World Mercator' (WGS 84) projected coordinate system. All map collar information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, or other information associated with the principal map. This map shows coastal features such as harbors, inlets, rocks, channels, points, coves, shoals, islands, and more. Includes also selected land features such as cities and towns, buildings. Depths shown by soundings. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection. The entire Atlantic Neptune atlas Vol. 3 : Charts of the coast and harbors of New England has been scanned and georeferenced as part of this selection.