Cosmogenic radionuclide production in NaI(Tl) crystals

arXiv:1411.0106v2.-- et al.The production of long-lived radioactive isotopes in materials due to the exposure to cosmic rays on Earth surface can be an hazard for experiments demanding ultra-low background conditions, typically performed deep underground. Production rates of cosmogenic isotopes in all the materials present in the experimental set-up, as well as the corresponding cosmic rays exposure history, must be both well known in order to assess the relevance of this effect in the achievable sensitivity of a given experiment. Although NaI(Tl) scintillators are being used in experiments aiming at the direct detection of dark matter since the first nineties of the last century, very few data about cosmogenic isotopes production rates have been published up to date. In this work we present data from two 12.5 kg NaI(Tl) detectors, developed in the frame of the ANAIS project, which were installed inside a convenient shielding at the Canfranc Underground Laboratory just after finishing surface exposure to cosmic rays. The very fast start of data taking allowed to identify and quantify isotopes with half-lives of the order of tens of days. Initial activities underground have been measured and then production rates at sea level have been estimated following the history of detectors; values of about a few tens of nuclei per kg and day for Te isotopes and 22Na and of a few hundreds for I isotopes have been found. These are the first direct estimates of production rates of cosmogenic nuclides in NaI crystals. A comparison of the so deduced rates with calculations using typical cosmic neutron flux at sea level and a carefully selected description of excitation functions will be also presented together with an estimate of the corresponding contribution to the background at low and high energies, which can be relevant for experiments aiming at rare events searches.This work has been supported by the Spanish Ministerio de Economía y Competitividad and the European Regional Development Fund (MINECO-FEDER) (FPA2011-23749), the Consolider-Ingenio 2010 Programme under grants MULTIDARK CSD2009-00064 and CPAN CSD2007-00042, and the Gobierno de Aragón (Group in Nuclear and Astroparticle Physics, ARAID Foundation and C. Cuesta predoctoral grant). C. Ginestra and P. Villar are supported by the MINECO Subprograma de Formación de Personal Investigador.Peer Reviewe

Selective C–Cl bond oxidative addition of chloroarenes to a POP–rhodium complex

The C–Cl bond cis oxidative addition of 12 chloroarenes, including chlorobenzene, chlorotoluenes, chlorofluorobenzenes, and di- and trichlorobenzenes to RhH{xant(PiPr2)2} (1; xant(PiPr2)2 = 9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene) and the ability of the resulting rhodium(III) species to undergo reductive elimination reactions are reported. Complex 1 reacts with chlorobenzene to give RhHCl(C6H5){xant(PiPr2)2} (2), which eliminates benzene to afford RhCl{xant(PiPr2)2} (3). On the other hand, in the presence of potassium tert-butoxide (KOtBu), it undergoes dehydrodechlorination to yield Rh(C6H5){xant(PiPr2)2} (4). The reactions of 1 with 3- and 4-chlorotoluenes lead to RhHCl(C6H4-3-Me){xant(PiPr2)2} (5) and RhHCl(C6H4-4-Me){xant(PiPr2)2} (6), respectively. Treatment of the acetone solutions of both compounds with KOtBu also results in their dehydrodechlorination to give Rh(C6H4-3-Me){xant(PiPr2)2} (7) and Rh(C6H4-4-Me){xant(PiPr2)2} (8). Chlorofluorobenzenes undergo both C–Cl oxidative addition and C–H bond activation in a competitive manner. The amount of the C–H activation product increases as fluorine and chlorine are separated. Complex 1 reacts with o-chlorofluorobenzene to afford the C–Cl oxidative addition product RhHCl(C6H4-2-F){xant(PiPr2)2} (9). The reaction of 1 with m-chlorofluorobenzene leads to RhHCl(C6H4-3-F){xant(PiPr2)2} (10; 91%) and the C–H bond activation product Rh(C6H3-2-Cl-6-F){xant(PiPr2)2} (12; 9%), whereas p-chlorofluorobenzene gives a mixture of RhHCl(C6H4-4-F){xant(PiPr2)2} (13; 61%) and Rh(C6H3-3-Cl-6-F){xant(PiPr2)2} (15; 39%). The addition of KOtBu to the acetone solutions of 9, 10, and 13 produces the HCl abstraction and the formation of Rh(C6H4-2-F){xant(PiPr2)2} (16), Rh(C6H4-3-F){xant(PiPr2)2} (17), and Rh(C6H4-4-F){xant(PiPr2)2} (18). In contrast to o-chlorofluorobenzene, 1,2-dichlorobenzene reacts with 1 to give RhHCl(C6H4-2-Cl){xant(PiPr2)2} (19; 32%), Rh(C6H4-2-Cl){xant(PiPr2)2} (20; 51%) and Rh(C6H3-2,3-Cl2){xant(PiPr2)2} (22; 17%). The reactions of 1 with 1,3- and 1,4-dichlorobenzene lead to the respective C–Cl bond oxidative addition products RhHCl(C6H4-3-Cl){xant(PiPr2)2} (23) and RhHCl(C6H4-4-Cl){xant(PiPr2)2} (24), which afford Rh(C6H4-3-Cl){xant(PiPr2)2} (25) and Rh(C6H4-4-Cl){xant(PiPr2)2} (26) by dehydrodechlorination with KOtBu in acetone. Treatment of 1 with 1,2,3-, 1,2,4-, and 1,3,5-trichlorobenzenes leads to RhHCl(C6H3-2,3-Cl2){xant(PiPr2)2} (27), RhHCl(C6H3-3,4-Cl2){xant(PiPr2)2} (28), and RhHCl(C6H3-3,5-Cl2){xant(PiPr2)2} (29). The addition of KOtBu to acetone solutions of 27-29 affords 22, Rh(C6H3-3,4-Cl2){xant(PiPr2)2} (30) and Rh(C6H3-3,5-Cl2){xant(PiPr2)2} (31).Financial support from the MINECO of Spain (Projects CTQ2014-52799-P and CTQ2014-51912-REDC), the Diputacion General de Aragon (E-35), FEDER, and the European Social Fund is acknowledged.Peer reviewe

Proyectos internacionales de bibliotecas virtuales en ciencias de la salud: características y buenas prácticas

The characteristics of a representative set of Health Sciences virtual libraries were analyzed with the further aim of identifying good practices that could be to put into practice in the Spanish context. Projects were selected in countries with a decentralized health management system similar the Spanish one. The following variables were analyzed: structure, financing, content, process coordination and interlibrary cooperation bodies. Also, good practices that can be applied to the Spanish national model were identified, of which we highlight the centralization of processes and the presence of organisms or interlibrary cooperation

Reacciones de formación de enlaces C-B y activación de enlaces C-Cl promovidas por complejos de Rodio(I) con un ligando pinza P,O,P

El trabajo recogido en esta tesis doctoral muestra que los complejos Rh(Bpin){ĸ3-P,O,P-[xant(PiPr2)2]} y RhH{ĸ3-P,O,P-[xant(PiPr2)2]} son bases de Lewis que promueven la inserción del triple enlace C-C de alquinos internos simétricos en los respectivos enlaces Rh-B y Rh-H y la adición oxidante de enlaces C-Cl y C-H de cloroarenos. Durante estos procesos, el ligando xant(PiPr2)2 demuestra una versatilidad extraordinaria, cambiando su modo de coordinación de mer-ĸ3-P,O,P a fac-ĸ3-P,O,P, cis-ĸ2-P,O,P y trans-ĸ2-P,O,P, adaptándose así a las necesidades electrónicas y estéricas de las nuevas especies generadas. Esta versatilidad es consecuencia de la hemilabilidad del átomo de oxígeno y de la flexibilidad del conector xanteno. Las reacciones de inserción conducen a derivados alquenilo plano-cuadrados, que experimentan isomerización E-Z vía intermedios rodaciclopropeno, y posterior activación de un enlace Cγ(sp3)-H del sustituyente alquilo unido al átomo de carbono Cα del ligando alquenilo o activación de un enlace C(sp2)-H aromático cuando el átomo de carbono Cβ lleva un sustituyente fenilo. Estas reacciones de isomerización y ruptura C-H son competitivas con reacciones de activación B-H y B-B de boranos y diboranos. Dependiendo del alquino, se han desarrollado diferentes procedimientos estequiométricos y catalíticos de borilación de alquinos internos.El estudio de los procesos de activación de enlaces C-Cl y C-H de cloroarenos promovidos por el complejo RhH{κ3-P,O,P-[xant(PiPr2)2]} ha puesto de manifiesto que las activaciones de los enlaces C-Cl están gobernadas por razones estéricas, mientras que las activaciones C-H están cinética y termodinámicamente desfavorecidas. Los productos de la adición del enlace C-Cl son complejos hidruro-cloruro-arilo de rodio(III), que tienen una marcada tendencia a la eliminación reductora de HCl por un mecanismo iónico. Este hecho ha permitido la preparación de una extensa familia de compuestos arilo de rodio(I) plano-cuadrados. El centro metálico de los complejos arilo coordina oxígeno molecular y monóxido de carbono, provocando transformaciones en las que participan estas moléculas y los ligandos de la esfera de coordinación del metal.<br /

Complejos de rodio e iridio con un ligando pinza POP: reacciones de borilación

Estos estudios revelan diferencias de comportamiento entre los fragmentos {xant(PiPr2)2}M de rodio e iridio, debido al mayor carácter reductor del iridio y su preferencia por formar compuestos saturados. Así, en el caso del iridio se aíslan complejos saturados d6 octaédricos, mientras que con rodio se obtienen los derivados insaturados d8 plano-cuadrados y d6 pentacoordinados. La rigidez y robustez proporcionada por la fosfina y la hemilabilidad del átomo de oxígeno permite estabilizar una gran variedad de compuestos insaturados con el fragmento {xant(PiPr2)2}Rh, siendo el complejo de rodio RhH{xant(PiPr3)2} el de mayor relevancia, ya que a partir de este derivado monohidruro hemos desarrollado un procedimiento sencillo para la síntesis de derivados plano-cuadrado insaturados de rodio(I) con ligandos sililo y borilo. Este complejo monohidruro promueve la activación C-H de arenos. Los productos de activación C-H dependen de los sustituyentes del areno. Los grupos metilo mantienen alejado al fragmento metálico, mientras que los sustituyentes flúor lo acercan. Por lo tanto, la selectividad observada sugiere que la activación C-H está controlada termodinámicamente. La activación B-H de boranos y C-H de arenos promovida por el complejo monohidruro hace posible la borilación estequiométrica y catalítica de arenos. El estudio etapa por etapa de la reacción, permite aislar y caracterizar los intermedios clave del proceso. El compuesto catiónico insaturado d6 pentacoordinado [RhH{Si(OH)Ph2}{xant(PiPr2)2}]+ se forma como resultado de la adición de un enlace O-H del agua al doble enlace Rh-Si de un intermedio silileno. De este modo, este derivado catiónico actúa como precursor de un catalizador muy eficiente para la monoalcohólisis selectiva de difenilsilano Durante el estudio experimental el mecanismo de la reacción de borilación por descianación mediada por rodio hemos aislado los intermedios implicados, siendo uno de ellos una especie plano-cuadrada ¿1-iminoacilo N-boril sustituida de rodio(I) sin precedentes en la bibliografía

Patrimonio cultural, películas cinematográficas y Depósito Legal

After an introduction about the present regulations on Legal Deposit in Spain and how it works, it is analised the deposit of films in this country not only as a matter of law but also as a real application. It can be noticed that althoug there have been some changes in this legal subject, there have never ben done films' deposit. It is explained the present situation about the deposit of films in the world and so about the different international references about the subject, making an special interest on the Project of the European Convention about the Protection of the Audiovisual National Heritage made by the Council of Cultural Cooperation in the Council of Europe. Finally, it is explained that for obtaining the preservation of films national heritage it is necessary to include the deposit of films in the legislation about legal deposit

Procedimiento de deshalogenación e hidrogenación de moléculas aromáticas halogenadas

Procedimiento de deshalogenación e hidrogenación de moléculas aromáticas halogenadas. Procedimiento de deshalogenación e hidrogenación consecutivos de moléculas aromáticas halogenadas en condiciones suaves de temperatura y de presión en presencia de un catalizador de complejos de rodio con ligandos bis (imino)piridina. Además, la invención se refiere a dichos complejos.Peer reviewedConsejo Superior de Investigaciones Científicas (España), Universidad de ZaragozaA1 Solicitud de patente con informe sobre el estado de la técnic

Polyhydrides of platinum group metals: nonclassical interactions and σ-bond activation reactions

This is an open access article published under an ACS AuthorChoice License.The preparation, structure, dynamic behavior in solution, and reactivity of polyhydride complexes of platinum group metals, described during the last three decades, are contextualized from both organometallic and coordination chemistry points of view. These compounds, which contain dihydrogen, elongated dihydrogen, compressed dihydride, and classical dihydride ligands promote the activation of B–H, C–H, Si–H, N–H, O–H, C–C, C–N, and C–F, among other σ-bonds. In this review, it is shown that, unlike other more mature areas, the chemistry of polyhydrides offers new exciting conceptual challenges and at the same time the possibility of interacting with other fields including the conversion and storage of regenerative energy, organic synthetic chemistry, drug design, and material science. This wide range of possible interactions foresees promising advances in the near future.Financial support form the MINECO of Spain (Projects CTQ2014-52799-P and CTQ2014-51912-REDC), the Diputación General de Aragón (E-35), FEDER, and the European Social Fund is acknowledged.Peer reviewe

Multicomponent Synthesis of Pyran-2-ylidene Chromium(0) and Tungsten(0) Fischer Carbene Complexes

A new reaction between chromium(0) and tungsten(0) carbene complexes 1 and alkynyl esters or ketones 2 in the presence of NMO to yield pyran-2-ylidene complexes 3 has been explored. Here, we discuss the scope of the reaction and propose a plausible mechanistic pathway. The method is a new multicomponent approach for the synthesis of pyranylidene carbene complexes.Financial support from theMICINN of Spain (project numbers CTQ2007-67730-C02-01/BQU (to M.A.S.), CTQ2008-00810 (to M.O.), and Consolider Ingenio 2010 CSD2007-00006), the Diputación General de Aragón (E35) (to M.O.), and the CAM (P2009/PPQ1634- AVANCAT) (toM.A.S.) is acknowledged.Peer Reviewe

Preparation, hydrogen bonds, and catalytic activity in metal-promoted addition of arylboronic acids to enones of a rhodium complex containing an NHC ligand with an alcohol function

The complex RhCl(COD){3-benzyl-1-(2-hydroxy-2-phenylethyl)imidazol-2- ylidene} has been prepared by reaction of the dimer [Rh(μ-OMe)(COD)] 2 with 3-benzyl-1-(2-hydroxy-2-phenylethyl)imidazolium chloride and characterized by X-ray diffraction analysis. The structure reveals that 75% of the molecules are associated through intermolecular O-H⋯Cl hydrogen bonds between the OH group of the NHC substituent of one molecule and the chloride ligand of the adjacent molecule. This complex catalyzes the addition of arylboronic acids to cyclic and acyclic enones in anhydrous toluene. The alcohol function of the substituent of the NHC ligand plays the role assigned to water in previous cases. © 2012 American Chemical Society.Financial support from the Ministerio de Ciencia e Innovación (MICINN) of Spain (Projects CTQ2007-65218, CTQ2011- 23459, CTQ2011-24165, Consolider Ingenio 2010 CSD2007- 00006), the Generalitat Valenciana (PROMETEO/2009/0349 and FEDER), the Diputación General de Aragón (E35), and the European Social Fund is acknowledged. I.P. thanks the MICINN for a predoctoral fellowship.Peer Reviewe