Dynamic Kinetic Resolution of Hetero biaryl Ketones by Zinc- Catalyzed Asymmetr ic Hydrosil ylation

Adiastereo- and highly enantioselective dynamic kinetic resolution (DKR) of configurationally labile hetero- biaryl ketones is described. The DKR proceeds by zinc- catalyze dhydrosilylation of the carbonyl group ,thus leading to secondary alcohols bearing axial and central chirality .The strategy relies on the labilization of the stereogenic axis that takes place thanks to aLewis acid–base interaction between anitrogen atom in the heterocycle and the ketone carbonyl group .The synthetic utility of the methodology is demonstrated through stereospecific transformations into either N,N-ligands or appealing axially chiral, bifunctional thiourea organocata- lysts.Ministerio de Ciencia e Innovación (Grants CTQ2016-76908-C2-1-P, CTQ2016-76908-C2-2-P, contract RYC-2013-12585)European FEDER FundsJunta de Andalucía (Grant 2012/FQM 10787)European Union - Marie Skłodowska-Curie (COFUND—Grant Agreement n 8 8 291780

The history of a quiet-Sun magnetic element revealed by IMaX/SUNRISE

Isolated flux tubes are considered to be fundamental magnetic building blocks of the solar photosphere. Their formation is usually attributed to the concentration of magnetic field to kG strengths by the convective collapse mechanism. However, the small size of the magnetic elements in quiet-Sun areas has prevented this scenario from being studied in fully resolved structures. Here we report on the formation and subsequent evolution of one such photospheric magnetic flux tube, observed in the quiet Sun with unprecedented spatial resolution (0\farcs 15 - 0\farcs 18) and high temporal cadence (33 s). The observations were acquired by the Imaging Magnetograph Experiment (IMaX) aboard the \textsc{Sunrise} balloon-borne solar observatory. The equipartition field strength magnetic element is the result of the merging of several same polarity magnetic flux patches, including a footpoint of a previously emerged loop. The magnetic structure is then further intensified to kG field strengths by convective collapse. The fine structure found within the flux concentration reveals that the scenario is more complex than can be described by a thin flux tube model with bright points and downflow plumes being established near the edges of the kG magnetic feature. We also observe a daisy-like alignment of surrounding granules and a long-lived inflow towards the magnetic feature. After a subsequent weakening process, the field is again intensified to kG strengths. The area of the magnetic feature is seen to change in anti-phase with the field strength, while the brightness of the bright points and the speed of the downflows varies in phase. We also find a relation between the brightness of the bright point and the presence of upflows within it.Comment: 13 pages. Accepted in ApJ. Animation 1 can be viewed and downloaded from: http://spg.iaa.es/downloads.as

A Dynamic Kinetic Asymmetric Heck Reaction for the Simultaneous Generation of Central and Axial Chirality

A highly diastereo- and enantioselective, scalable Pd-catalyzed dynamic kinetic asymmetric Heck reaction of heterobiaryl sulfonates with electron-rich olefins is described. The coupling of 2,3-dihydrofuran or N-boc protected 2,3-dihydropyrrole with a variety of quinoline, quinazoline, phthalazine, and picoline derivatives takes place with simultaneous installation of central and axial chirality, reaching excellent diastereo- and enantiomeric excesses when in situ formed [Pd0/DM-BINAP] was used as the catalyst, with loadings reduced down to 2 mol % in large scale reactions. The coupling of acyclic, electron-rich alkenes can also be performed using a [Pd0/Josiphos ligand] to obtain axially chiral heterobiaryl α-substituted alkenes in high yields and enantioselectivities. Products from Boc-protected 2,3-dihydropyrrole can be easily transformed into N,N ligands or appealing axially chiral, bifunctional proline-type organocatalysts. Computational studies suggest that a β-hydride elimination is the stereocontrolling step, in agreement with the observed stereochemical outcome of the reaction.Ministerio de Ciencia e Innovación (Grants CTQ2016-76908-C2-1-P; CTQ2016-76908-C2-2-P; CTQ2016-78083-P; RYC-2013-12585)European Commission (FEDER Programme)Junta de Andalucía (Grant 2012/FQM 10787)Universidad de Sevilla (Grant No. 1800511201)European Union - Marie Skłodowska-Curie (COFUND—Grant Agreement nº 291780

Effect of pore generator on microstructure and resistivity of Sb2O3 and CuO doped SnO2 electrodes

[EN] Sb(2)O(3)and CuO doped SnO(2)ceramic electrodes could be an alternative to the ones currently used ones in the electrooxidation process of water pollutants. The rise of electrode surface by introducing a porogen agent on the composition was analysed in order to increase the electrochemical active surface. For this reason, several substances were tested. Although the densification and total pore volume had similar values, the microstructures and the pore size distributions generated were strongly dependent on porogen nature. A total of five porogens were tested, but petroleum coke turned out to be the best option for these electrodes. It was found that the electrical resistivity depends on the nature of pore generator. Furthermore, its relation to the porosity can be modelled with Archie's or Pabst's equations.The authors are very grateful to the Ministerio de Economia y Competitividad (Projects: CTQ2015-65202-C2-1-R and CTQ2015-65202-C2-2-R) and to the European Regional Development Fund (FEDER), for their economic support.Sánchez-Rivera, M.; Gozalbo, A.; Pérez-Herranz, V.; Mestre, S. (2020). Effect of pore generator on microstructure and resistivity of Sb2O3 and CuO doped SnO2 electrodes. Journal of Porous Materials. 27(6):1801-1808. https://doi.org/10.1007/s10934-020-00959-0S18011808276C.A. Martínez-Huitle, S. Ferro, Electrochemical oxidation of organic pollutants for the wastewater treatment: direct and indirect processes. Chem. Soc. Rev. 35, 1324–1340 (2006). https://doi.org/10.1039/B517632HC.A. Kent, J.J. Concepcion, C.J. Dares, D.A. Torelli, A.J. Rieth, A.S. Miller, P.G. Hoertz, T.J. Meyer, Water oxidation and oxygen monitoring by cobalt-modified fluorine-doped tin oxide electrodes. J. Am. 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Salvadó, M. Vendrell-Saz, Evidence of tin oxide recrystallization in opacified lead glazes. J. Am. Ceram. Soc. 82, 2871–2875 (2004). https://doi.org/10.1111/j.1151-2916.1999.tb02170.xP.P. Tsai, I.-C. Chen, M.H. Tzeng, Tin oxide (SnOX) carbon monoxide sensor fabricated by thick-film methods. Sensors Actuators B 25, 537–539 (1995). https://doi.org/10.1016/0925-4005(95)85116-XF. Li, J. Xu, X. Yu, L. Chen, J. Zhu, Z. Yang, X. Xin, One-step solid-state reaction synthesis and gas sensing property of tin oxide nanoparticles. Sensors Actuators B 165–169. http://www.sciencedirect.com/science/article/pii/S0925400501009479S. Zuca, M. Terzi, M. Zaharescu, K. Matiasovsky, Contribution to the study of SnO2-based ceramics. J. Mater. Sci. 26, 1673–1676 (1991). https://doi.org/10.1007/BF00544681M. BATZILL, U. DIEBOLD, The surface and materials science of tin oxide. Prog. Surf. Sci. 79, 47–154 (2005). https://doi.org/10.1016/j.progsurf.2005.09.002G. Monrós. El color de la cerámica: nuevos mecanismos en pigmentos para los nuevos procesados de la industria cerámica, n.d. https://books.google.es/books/about/El_Color_de_la_cerámica.html?id=yfIogcGvdqUC&redir_esc=y . Accessed 29 Aug 2018E.R. Leite, J.A. Cerri, E. Longo, J.A. Varela, C.A. Paskocima, Sintering of ultrafine undoped SnO2 powder. J. Eur. Ceram. Soc. 21, 669–675 (2001). https://doi.org/10.1016/S0955-2219(00)00250-8S. Mihaiu, O. Scarlat, G. Aldica, M. Zaharescu, SnO2 electroceramics with various additives. J. Eur. Ceram. Soc. 21, 1801–1804 (2001). https://doi.org/10.1016/S0955-2219(01)00119-4C.R. Foschini, L. Perazolli, J.A. Varela, Sintering of tin oxide using zinc oxide as a densification aid. J. Mater. Sci. 39, 5825–5830 (2004). https://doi.org/10.1023/B:JMSC.0000040095.03906.61M.S. Castro, C.M. Aldao, Characterization of SnO2-varistors with different additives. J. Eur. Ceram. Soc. 18, 2233–2239 (1998). https://doi.org/10.1016/S0955-2219(97)00130-1A.-M. Popescu, S. Mihaiu, S. Zuca, Microstructure and electrochemical behaviour of some SnO2-based inert electrodes in aluminium electrolysis. Zeitschrift Für Naturforsch. A 57, 71–75 (2002). https://doi.org/10.1515/zna-2002-1-210M.R. Sahar, M. Hasbullah, Properties of SnO2-based ceramics. 30, 5304–5305 (1995)D. Nisiro, G. Fabbri, G.C. Celotti, A. Bellosi, Influence of the additives and processing conditions on the characteristics of dense SnO2-based ceramics. J. Mater. Sci. 38, 2727–2742 (2003). https://doi.org/10.1023/A:1024459307992M.-J. Sánchez-Rivera, CuO improved (Sn,Sb)O2 ceramic anodes for electrochemical advanced oxidation processes. Int. J. Appl. Ceram. Technol. (2018)B. Das, B. Chakrabarty, P. Barkakati, Preparation and characterization of novel ceramic membranes for micro-filtration applications. Ceram. Int. 42, 14326–14333 (2016). https://doi.org/10.1016/j.ceramint.2016.06.125I. Hedfi, N. Hamdi, M.A. Rodriguez, E. Srasra, Development of a low cost micro-porous ceramic membrane from kaolin and Alumina, using the lignite as porogen agent. Ceram. Int. 42, 5089–5093 (2016). https://doi.org/10.1016/j.ceramint.2015.12.023M. García-Gabaldón, V. Pérez-Herranz, E. Sánchez, S. Mestre, Effect of porosity on the effective electrical conductivity of different ceramic membranes used as separators in eletrochemical reactors. J. Memb. Sci. 280, 536–544 (2006). https://doi.org/10.1016/j.memsci.2006.02.007J.-H. Kim, K.-H. Lee, Effect of PEG additive on membrane formation by phase inversion. J. Memb. Sci. 138, 153–163 (1998). https://doi.org/10.1016/S0376-7388(97)00224-XB.K. Nandi, R. Uppaluri, M.K. Purkait, Preparation and characterization of low cost ceramic membranes for micro-filtration applications. Appl. Clay Sci. 42, 102–110 (2008). https://doi.org/10.1016/j.clay.2007.12.001F. Bouzerara, A. Harabi, S. Condom, Porous ceramic membranes prepared from kaolin. Desalin. 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Evaluating the Impact of Broadband Access and Internet Use in a Small Underserved Rural Community

Having adequate access to the internet at home enhances quality-of-life for households and facilitates economic and social opportunities. Despite increased investment in response to the COVID-19 pandemic, millions of households in the rural United States still lack adequate access to high-speed internet. In this study, we evaluate a wireless broadband network deployed in Turney, a small, underserved rural community in northwest Missouri. In addition to collecting survey data before and after this internet intervention, we collected pre-treatment and post-treatment survey data from comparison communities to serve as a control group. Due to technical constraints, some of Turney\u27s interested participants could not connect to the network, creating an additional comparison group. These comparisons suggest two primary findings, (1) changes in using the internet for employment, education, and health could not be directly attributed to the internet intervention, and (2) the internet intervention was associated with benefits stemming from the ability to use multiple devices at once. This study has implications for the design of future broadband evaluation studies, particularly those examining underserved rather than unserved communities. Recommendations for identifying appropriate outcome variables, executing recruitment strategies, and selecting the timing of surveys are made

Evaluating the Impact of Broadband Access and Internet Use in a Small Underserved Rural Community

Having adequate access to the internet at home enhances quality-of-life for households and facilitates economic and social opportunities. Despite increased investment in response to the COVID-19 pandemic, millions of households in the rural United States still lack adequate access to high-speed internet. In this study, we evaluate a wireless broadband network deployed in Turney, a small, underserved rural community in northwest Missouri. In addition to collecting survey data before and after this internet intervention, we collected pre-treatment and post-treatment survey data from comparison communities to serve as a control group. Due to technical constraints, some of Turney\u27s interested participants could not connect to the network, creating an additional comparison group. These comparisons suggest two primary findings, (1) changes in using the internet for employment, education, and health could not be directly attributed to the internet intervention, and (2) the internet intervention was associated with benefits stemming from the ability to use multiple devices at once. This study has implications for the design of future broadband evaluation studies, particularly those examining underserved rather than unserved communities. Recommendations for identifying appropriate outcome variables, executing recruitment strategies, and selecting the timing of surveys are made

Tratamiento de la biodiversidad en los textos escolares de la educación secundaria en España

El presente trabajo estudia el tratamiento del concepto de diversidad biológica, en los libros de texto de la ESO y del Bachillerato de España. Para ello, se define el ámbito conceptual de la biodiversidad atendiendo a la visión que ofrece la comunidad de expertos con el objetivo de servir de referente epistemológico en el proceso de análisis. Los resultados muestran una multiplicidad de definiciones de la biodiversidad, con un fuerte predominio de reducirlo al número de especies, lo que pone en evidencia su des-actualización. A la luz de este estudio, el listado de contenidos del currículo oficial no garantizaría la transposición de una conceptualización de biodiversidad más actual

Executive functioning skills and (low) math achievement in primary and secondary school

Schoolchildren with better executive functioning skills achieve better mathematics results. It is less clear how inhibition, cognitive flexibility, and working memory combine to predict mathematics achievement and difficulty throughout primary and secondary school. This study aimed to find the best combination of executive function measures for predicting mathematical achievement in Grades 2, 6, and 10 and to test whether this combination predicts the probability of having mathematical difficulties across school grades even when fluid intelligence and processing speed were included in the models. A total of 426 students—141 2nd graders (72 girls), 143 6th graders (72 girls), and 142 10th graders (79 girls)—were cross-sectionally assessed with 12 executive tasks, one standardized mathematical task, and a standardized test of intelligence. Bayesian regression analyses found various combinations of executive predictors of mathematical achievement for each school grade spanning Grade 2 to measures of cognitive inhibition (negative priming) and cognitive flexibility (verbal fluency); Grade 6 to measures of inhibition: resistance to distractor interference (receptive attention), cognitive flexibility (local–global), and working memory (counting span); and Grade 10 to measures of inhibition: resistance to distractor interference (receptive attention) and prepotent response inhibition (stop signal) and working memory (reading span). Logistic regression showed that the executive models derived from the Bayesian analyses had a similar ability to classify students with mathematical difficulty and their peers with typical achievement to broader cognitive models that included fluid intelligence and processing speed. Measures of processing speed, cognitive flexibility (local–global), and prepotent response inhibition (stop signal) were the main risk factors in Grades 2, 6, and 10, respectively. Cognitive flexibility (verbal fluency) in Grade 2 and fluid intelligence, which was more stable in all three grades, acted as protective factors against mathematical difficulty. These findings inform practical considerations for establishing preventive and intervention proposals.Ministerio de Ciencia e Innovación | Ref. EDU2011-2269

On the strong discontinuity approach in finite deformation settings

Taking the strong discontinuity approach as a framework for modelling displacement discontinuities and strain localization phenomena, this work extends previous results in infinitesimal strain settings to finite deformation scenarios. By means of the strong discontinuity analysis, and taking isotropic damage models as target continuum (stress–strain) constitutive equation, projected discrete (tractions–displacement jumps) constitutive models are derived, together with the strong discontinuity conditions that restrict the stress states at the discontinuous regime. A variable bandwidth model, to automatically induce those strong discontinuity conditions, and a discontinuous bifurcation procedure, to determine the initiation and propagation of the discontinuity, are briefly sketched. The large strain counterpart of a non-symmetric finite element with embedded discontinuities, frequently considered in the strong discontinuity approach for infinitesimal strains, is then presented. Finally, some numerical experiments display the theoretical issues, and emphasize the role of the large strain kinematics in the obtained result