The formation of the Alleghenian Isthmus triggered the Bashkirian glaciation: Constraints from warm-water benthic foraminifera

© 2017 Elsevier B.V. The timing of the final collision of Laurentia and Gondwana as well as the disappearance of the gateway between the Rheic and Tethyan oceans are quite controversial and poorly established. Accurate constraints on the gateway closure are vitally important for the understanding of global sea-level fluctuations, ocean circulation, regional and global environments, salinity and reorganization of the thermohaline circulation in the western Tethys, the Bashkirian glacial episode and the overall decline of atmospheric CO 2 concentrations. Here we present a new approach by applying warm-water benthic foraminifera (WWBF) data to precisely constrain the Rheic-Tethys gateway (RTG) closure, utilizing taxonomic and statistical methods. The link to the RTG closure and the profound biotic transformations in the oceans, sea-level, and expansion of the Gondwana ice sheet are discussed herein. The WWBF records in the studied regions constrain the timing of the RTG disappearance and support a linkage between the appearance of the Alleghenian Isthmus and the onset of the Bashkirian glaciation

Mississippian reef development in the Cracoe Limestone Formation of the southern Askrigg Block, North Yorkshire, UK

The southern margin of the Askrigg Block around Cracoe, North Yorkshire, shows a transition from carbonate ramp to reef-rimmed shelf margin, which, based on new foraminiferal/algal data, is now constrained to have initiated during the late Asbian. A late Holkerian to early Asbian ramp facies that included small mudmounds developed in comparatively deeper waters, in a transition zone between the proximal ramp, mudmound-free carbonates of the Scaleber Quarry Limestone Member (Kilnsey Formation) and the distal Hodderense Limestone and lower Pendleside Limestone formations of the adjacent Craven Basin. The ramp is envisaged as structurally fragmented, associated with sudden thickness and facies changes. The late Asbian to early Brigantian apron reefs and isolated reef knolls of the Cracoe Limestone Formation include massive reef core and marginal reef flank facies, the latter also including development of small mudmounds on the deeper water toes of back-reef flanks. The position of the apron/knoll reefs is constrained to the south (hangingwall) of the North Craven Fault, but it is syn-depositional displacement on the Middle Craven Fault that accounts for the thick reefal development. Subsequent inversion of this structure during the early Brigantian caused uplift and abandonment of the reefs and consequent burial by the Bowland Shale Formation

Google Scholar Metrics evolution: an analysis according to languages

The final publication is available at Springer via http://dx.doi.org/10.1007/s11192-013-1164-8In November 2012 the Google Scholar Metrics (GSM) journal rankings were updated, making it possible to compare bibliometric indicators in the ten languages indexed—and their stability—with the April 2012 version. The h-index and h-5 median of 1,000 journals were analysed, comparing their averages, maximum and minimum values and the correlation coefficient within rankings. The bibliometric figures grew significantly. In just seven and a half months the h-index of the journals increased by 15 % and the median h-index by 17 %. This growth was observed for all the bibliometric indicators analysed and for practically every journal. However, we found significant differences in growth rates depending on the language in which the journal is published. Moreover, the journal rankings seem to be stable between April and November, reinforcing the credibility of the data held by Google Scholar and the reliability of the GSM journal rankings, despite the uncontrolled growth of Google Scholar. Based on the findings of this study we suggest, firstly, that Google should upgrade its rankings at least semi-annually and, secondly, that the results should be displayed in each ranking proportionally to the number of journals indexed by language.Orduña Malea, E.; Delgado López-Cózar, E. (2014). Google Scholar Metrics evolution: an analysis according to languages. Scientometrics. 98(3):2353-2367. doi:10.1007/s11192-013-1164-8S23532367983Aguillo, & Isidro, F. (2012). Is Google Scholar useful for bibliometrics? A webometric analysis. Scientometrics, 91(2), 343–351.Brewington, B. E., & Cybenko, G. (2000). How dynamic is the Web? Computer Networks, 33(1–6), 257–276.Chen, X. (2010). Google Scholar’s dramatic coverage improvement five years after debut. Serials Review, 36(4), 221–226.Cho, Y. & Garcia-Molina, H. (2000). The evolution of the web and implications for an incremental crawler. Proceedings of the 26th International Conference on very large data bases, 200–209.Costas, R., & Bordons, M. (2007). The h-index: advantages, limitations and its relation with other bibliometric indicators at the micro level. Journal of Informetrics, 1(3), 193–203.de Winter, J. C. F., Zadpoor, A. A., & Dodou, D. (2013). The expansion of Google Scholar versus Web of Science: a longitudinal study. Scientometrics. doi: 10.1007/s11192-013-1089-2 .Delgado López-Cózar, E., & Cabezas-Clavijo, A. (2012). Google Scholar Metrics: an unreliable tool for assessing scientific journals. El profesional de la información, 21(4), 419–427.Delgado López-Cózar, E., & Cabezas-Clavijo, A. (2013). Ranking journals: could Google Scholar metrics be an alternative to journal citation reports and Scimago journal ranks. Learned publishing, 26(2), 101–114.Fetterly, D., Manasse, M., Najork, M. & Wiener, J. (2003). A large scale study of the evolution of web pages. Proceedings of the Twelfth International Conference on World Wide Web, 669–678.Harzing, A.-W. (2013). A preliminary test of Google Scholar as a source for citation data: a longitudinal study of Nobel prize winners. Scientometrics, 94(3), 1057–1075.Jacsó, P. (2012). Google Scholar Metrics for Publications—The software and content feature of a new open access bibliometric service. Online Information Review, 36(4), 604–619.Koehler, W. (2002). Web page change and persistence-4-year longitudinal web study. Journal of the American Society for Information Science and Technology, 53(2), 162–171.Koehler, W (2004). A longitudinal study of Web pages continued a consideration of document persistence. Information Research, 9(2). http://informationr.net/ir/9-2/paper174.html . Accessed 1 Sep 2013.Kousha, K., & Thelwall, M. (2007). Google Scholar Citations and Google Web/URL citations: a multidiscipline exploratory analysis. Journal of the American Society for Information Science and Technology, 58(7), 1055–1065.Leydesdorff, L. (2012). World shares of publications of the USA, EU-27, and China compared and predicted using the new Web of Science interface versus Scopus. El profesional de la información, 21(1), 43–49.Neuhaus, C., Neuhaus, E., Asher, A., & Wrede, C. (2006). The depth and breadth of Google Scholar: An empirical study. Libraries and the Academy, 6(2), 127–141.Orduña-Malea, E., Serrano-Cobos, J., & Lloret-Romero, N. (2009). Las universidades públicas españolas en Google Scholar: presencia y evolución de su publicación académica web. El profesional de la información, 18(5), 493–500.Orduña-Malea, E., Serrano-Cobos, J., Ontalba-Ruipérez, J.-A., & Lloret-Romero, N. (2010). Presencia y visibilidad web de las universidades públicas españolas. Revista española de documentación científica, 33(2), 246–278.Ortega, J. L., Aguillo, I. F., & Prieto, J. A. (2006). Longitudinal study of contents and elements in the scientific Web environment. Journal of Information Science, 32(4), 344–351.Payne, N., & Thelwall, M. (2007). A longitudinal study of academic webs: growth and stabilization. Scientometrics, 71(3), 523–539

Role of imine isomerization in the stereocontrol of the Staudinger reaction between ketenes and imines

Computational–experimental analysis has allowed determining that the stereochemistry of the Staudinger reaction between ketenes and imines is strongly associated with the nature of the imine, which affects the two steps of the reaction. The first step, namely the nucleophilic attack of the sp2-hybridized nitrogen atom of the imine on the sp-hybridized carbon atom of the ketene, is affected by the energetically accessible in situ isomerization patterns of the imine. The second step consists of a conrotatory electrocyclization of the zwitterionic intermediate formed in the previous step. This latter pericyclic step depends on the inward/outward torquoelectronic effects generated by the substituents of the imine. The impact of these factors on the stereochemistry of this reaction has been analyzed kinetically by numerical methods. The results of these simulations are compatible with the experimental results and support these conclusions

Proton Conduction Properties of Metal phosphonates and Application as Fillers in PEMFCs

Metal phosphonate (MP)-based coordination polymers (CPs) are structurally versatile multifunctional compounds containing different acidic groups such as P-OH; SO3H, COOH, N+-H, etc. These features result in the formation of extended H-bond networks and confer a wide range of proton conduction properties to be used as components of membrane electrode assemblies (MEAs).In this work, the focus is placed on the proton conduction properties of coordination polymers derived from the combination of lanthanide ions with different multifunctional phosphonic ligands, such as phosphonotaurine (2-[bis(phosphonomethyl)amino]-ethanesulfonic acid) or nitrilo-tris (methylenephosphonic acid). High-throughput hydrothermal screening has been used to reach optimal synthesis conditions. Their crystal structures were solved ab initio from X-ray powder or single-crystal diffraction data. Proton conductivities of the MPs and Nafion-mixed membranes were determined by electrochemical impedance spectroscopy (EIS). We report the synthesis and structural features of several members of both families of MPs. The presence of the different functional groups in these ligands such us free sulfonic groups or the incorporating sulphate species into the framework of CPs, lead to a wide variety of metal ligand coordination modes and frameworks, which determine their proton conductivity properties, ranged between 10−3 and 10−2 S·cm−1 at 90 °C and 95% RH. Selected materials were studied as fillers for the preparation of Nafion-mixed membranes, and their responses in proton exchange membrane fuel cells (PEMFCs) were established under operating conditions. The structural role and orientation of the acid groups of the ligand contribute to tune the H-bonding networks and, hence, the proton transfer processes. Preliminary results indicate that these solids perform satisfactorily as fillers of Nafion-based membranes, showing power and current densities higher than those of the pristine Nafion in short times.Esta invetigación fue financiada por los proyectos de investigación PID2019−110249RB-I00 (MICIU/AEI, España) y PY20−00416 (Junta de Andalucía, España/FEDER). M.B.G. agradece la ayuda a los contratatos PAIDI2020 DOC_00272 Junta de Andalucía, España) y R.M.P.C.agradece a la Universidad de Málaga con el Plan Propio de Investigación por la financiación prestada

Cobalt phosphinates as precursors of cobalt phosphide electrocatalysts

https://qies22.icms.us-csic.es/The scarcity and high cost of Pt and Ru/Ir-based noble metal electrocatalysts forces to design alternative low-cost and efficient materials for sustainable energy storage and conversion technologies. Among them, phosphorus-containing coordination polymers, such as phosphinates, have emerged as potential precursors of transition-metal phosphide (TMP) electrocatalysts. The possibility of incorporating two funtionalized organic moieties into the phosphinate ligands makes metal phosphinates highly attractive precursors to obtain core-shell carbon/TMP electrocatalysts. In this research-work, we report the synthesis and crystal structure of two Co2+-phosphinates derived from the (2-carboxyethyl)(phenyl)phosphinic acid (CEPPA), Co2[(O2P(CH2CH2COO)(C6H5)(H2O)]2·2H2O (CoCEPPA-1D) and Co3[O2P(CH2CH2COO)(C6H5)]2(OH)2 (CoCEPPA-2D), synthesized by microwave-assisted method. These solids were used as precursor of cobalt phosphides (Co2P/CoP) by thermal reduction under 5%H2-Ar atmosphere at different temperatures and their electrocatalytic performances were investigated toward Oxygen Evolution Reaction (OER), Oxygen Reduction Reaction (ORR) and Hydrogen Evolution Reaction (HER). The relationship between Co/P molar ratios and/or the Co2+ coordination environment in the precursor structures and the electrocatalytic activity of the prepared cobalt phosphides will be discussed.Proyectos de investigación PID2019-110249RB-I00 (MICIU/AEI, Ministerio de España) y PY20-00416 (Junta de Andalucia, Spain/FEDER). Ayudas para Doctores PAIDI2020 (DOC_00272 Junta de Andalucia, España) y Plan Propio de Investigación de la Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Coverage of highly-cited documents in Google Scholar, Web of Science, and Scopus: a multidisciplinary comparison

This study explores the extent to which bibliometric indicators based on counts of highly-cited documents could be affected by the choice of data source. The initial hypothesis is that databases that rely on journal selection criteria for their document coverage may not necessarily provide an accurate representation of highly-cited documents across all subject areas, while inclusive databases, which give each document the chance to stand on its own merits, might be better suited to identify highly-cited documents. To test this hypothesis, an analysis of 2,515 highly-cited documents published in 2006 that Google Scholar displays in its Classic Papers product is carried out at the level of broad subject categories, checking whether these documents are also covered in Web of Science and Scopus, and whether the citation counts offered by the different sources are similar. The results show that a large fraction of highly-cited documents in the Social Sciences and Humanities (8.6%-28.2%) are invisible to Web of Science and Scopus. In the Natural, Life, and Health Sciences the proportion of missing highly-cited documents in Web of Science and Scopus is much lower. Furthermore, in all areas, Spearman correlation coefficients of citation counts in Google Scholar, as compared to Web of Science and Scopus citation counts, are remarkably strong (.83-.99). The main conclusion is that the data about highly-cited documents available in the inclusive database Google Scholar does indeed reveal significant coverage deficiencies in Web of Science and Scopus in several areas of research. Therefore, using these selective databases to compute bibliometric indicators based on counts of highly-cited documents might produce biased assessments in poorly covered areas.Alberto Martín-Martín enjoys a four-year doctoral fellowship (FPU2013/05863) granted by the Ministerio de Educación, Cultura, y Deportes (Spain)

Exploiting the Multifunctionality of M2+/Imidazole−Etidronates for Proton Conductivity (Zn2+) and Electrocatalysis (Co2+, Ni2+) toward the HER, OER, and ORR

This work deals with the synthesis and characterization of one-dimensional (1D) imidazole-containing etidronates, [M2(ETID)(Im)3]·nH2O (M = Co2+ and Ni2+; n = 0, 1, 3) and Zn2(ETID)2(H2O)2](Im)2, as well as the corresponding Co2+/Ni2+ solid solutions. Depending on the water content, metal ions in the isostructural Co2+ and Ni2+ derivatives are octahedrally coordinated (n = 3) or consist of octahedral together with dimeric trigonal bipyramidal (n = 1) or square pyramidal (n = 0) environments. The imidazole molecule acts as a ligand (Co2+, Ni2+ derivatives) or charge-compensating protonated species (Zn2+ derivative). For the latter, the proton conductivity is determined to be ∼6 × 10−4 S·cm−1 at 80 °C and 95% relative humidity (RH). By pyrolyzing in 5%H2−Ar at 700−850 °C, core−shell electrocatalysts consisting of Co2+-, Ni2+-phosphides or Co2+/Ni2+-phosphide solid solution particles embedded in a N-doped carbon graphitic matrix are obtained, which exhibit improved catalytic performances compared to the non-N-doped carbon materials. Co2+ phosphides consist of CoP and Co2P in variable proportions according to the used precursor and pyrolytic conditions. However, the Ni2+ phosphide is composed of Ni2P exclusively at high temperatures. Exploration of the electrochemical activity of these metal phosphides toward the OER, ORR, and HER reactions reveals that the anhydrous Co2(ETID)(Im)3 pyrolyzed at 800 °C (CoP/Co2P = 80/20 wt %) is the most active trifunctional electrocatalyst, with good integrated capabilities as an anode for overall water splitting (cell voltage of 1.61 V) and potential application in Zn−air batteries. This solid also displays a moderate activity for the HER with an overpotential of 156 mV and a Tafel slope of 79.7 mV·dec−1 in 0.5 M H2SO4. Ni2+- and Co2+/Ni2+-phosphide solid solutions show lower electrochemical performances, which are correlated with the formation of less active crystalline phases.The work at UMA was funded by PID2019-110249RB-I00 (MICIU/AEI, Spain) and PY20-00416 (Junta de Andalucia, Spain/FEDER) research projects. A.V.-C. thanks MICIU for PRE2020-094459 student grant; M.B.-G. thanks PAIDI2020-DOC_00272 research grant (Junta de Andalucia, Spain) and R.M.P.C. thanks University of Malaga under Plan Propio de Investigación for financial support. Funding for open access charge: Universidad de Málaga/CBUA (PMCID# PMC8915163