Advances in direct methods for small molecules and proteins

La teoría de las representaciones presenta una serie de limitaciones para estimar la fase de los triplets utilizando todo el espacio recíproco. Con una nueva fórmula denominada P13 se produce una mejor estimación que las fórmulas anteriores pero siendo necesario un tiempo computacional mayor. Un nuevo procedimiento de normalización, en el caso de las proteínas, empleando la función de distribución p(A) y usando técnicas de ajustes histográmicos, minimiza los errores en el escalado de los A's y por tanto optimiza el proceso de asignación de fases. Se presentan dos criterios que excluyen reflexiones que no aportan información al mapa de densidades. La información así obtenida podría extenderse a las reflexiones hasta la resolución de la protína nativa mediante la aplicación de una fórmula que hace uso de la información de un modelo parcial. Este método resulta ser bastante efectivo cuando se conoce un 20-40% de la estructura total

Ultrasound-Guided Percutaneous Neuromodulation in Multiple Sclerosis: A Case Report

Multiple sclerosis is a degenerative inflammatory disease that causes different musculoskeletal problems. Its impact has led to the study of treatment alternatives such as the use of invasive physiotherapy. In this study, we analyze the effects of ultrasound-guided percutaneous neuromodulation to a 51-year-old man suffering from multiple sclerosis and an associated hemiparesis in the left upper limb. A dry needling needle was placed in contact with the median nerve under ultrasound guidance and 10 trains of 10 seconds of electrostimulation with a frequency of 10 Hz and an impulse width of 240 µs were applied, with 10 seconds of pause between them. There was a significant improvement in the grip strength immediately after the treatment which increased progressively at 24 hours and at 4 days follow-up. There was also an improvement in the hand function, with a decrease in the time necessary to perform the 9 Hole Peg Test immediately after the treatment, which was maintained at 24 hours and at 4 days follow-up. Future studies with larger samples are needed to further test the effects of this invasive physiotherapy technique as well as its possible applications to other neurological conditions

From conjugated tertiary skipped diynes to chain-functionalized tetrasubstituted pyrroles

A novel and metal-free method for the synthesis of chain-functionalized tetrasubstituted pyrroles from easily accessible tertiary skipped diynes, was reported. The method involved modular synthesis of chain functionalized tetrasubstituted pyrroles from easily available alkyl porpiolates, acid chlorides, and primary amine. The method used a primary amine for the nitrogen source and utilized the reactivity profile of tertiary 1,4-diyne scaffolds. The synthetic manifold in the method operated in the absence of metals and accelerated by the nucleophilic addition of a primary amine on the alkynoate function. Anti-Michael ring-closing hydroamination and a [3,3]-sigmatropic rearrangement helped to complete the process of producing pyrrole. It was observed during the process that the enamine formation is more faster than the enamine cyclization.Authors thank the Spanish Ministerio de Educación y Ciencia and the European Regional Development Fund (CTQ2005-09074-C02-02), the Spanish MSC ISCIII (RETICS RD06/0020/1046), CSIC (Proyecto Intramural Especial 200719) and Fundación Instituto Canario de Investigación del Cáncer (FICI-G.I. No. 08/2007) for financial support. S.L.-T. Thanks MEC for a FPU grant.Peer Reviewe

Tertiary skipped diynes: A pluripotent building block for the modular and diversity-oriented synthesis of nitrogen heterocycles

Dominos! The multivalent reactivity profile of tertiary skipped diynes has been conveniently exploited in the domino and diversity-oriented synthesis of fully substituted pyrazoles and 1, 4-diazepane derivatives (see scheme). The developed manifold is chemically efficient and simple to operate. In addition, the resulting Ncontaining heterocycles are obtained in a regio- and chemoselective manner. (Chemical Equation Presented) © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.This research was supported by the Spanish Ministerio de Ciencia e Innovación, the European Regional Development Fund (CTQ2008-06806-C02-02), the Spanish MSC ISCIII (RETICS RD06/0020/1046), FUNCIS (REDESFAC PI01/06) and the Fundación Instituto Canario de Investigación del Cancer (FICI-G.I.N808/2007). S.L.-T. thanks the Spanish MEC for an FPU grant. The authors thank technician Anna Jurado Varona for her experimental assistance.Peer Reviewe

Diverted domino reactivity in tertiary skipped diynes: A convenient access to polyfunctionalized cyclohexadienones and multivalent aromatic scaffolds

Diverting is the game! A new domino manifold has been implemented for the synthesis of cyclohexadienone-based scaffolds from tertiary skipped diynes and secondary amines. The manifold takes advantage of a new O-enolate-driven reactivity pattern discovered for these diynes. The scaffolds are conveniently transformed into the corresponding multivalent salicylate derivatives (see scheme). © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.This research was supported by the Spanish MICINN and the European RDF (CTQ2008–06806-C02–02), the Spanish MSC ISCIII (RETICS RD06/0020/1046), FUNCIS (PI 43/09). S. L.-T. thanks the Spanish MEC for a FPU grant. The authors thank technician Ms. Anna Jurado Varona for her experimental assistance.Peer Reviewe

Potential energy surface and spectroscopy of clusters of rare-gas atoms with cyclopropane

Analytical empirical potential energy surfaces describing the van der Waals interaction between rare-gas atoms and cyclopropane are presented. The functional form is based on pairwise Lennard-Jones-type potentials which have been widely used to describe rare-gas-benzene complexes, also studied in this work in order to check our theoretical method and for comparison. The parameters have been chosen in order to accurately fit the high resolution microwave spectra recently reported by Xu and Jäger [J. Chem. Phys. 106, 7968 (1997)]. The observed splitting in the microwave spectra of Ne-cyclopropane, associated with rotational tunneling, is well reproduced. Moreover, such tunneling is also important for complexes of Ar and Kr in excited van der Waals states. These phenomena involve a high delocalization of the wave functions and, therefore, intermolecular spectroscopy techniques would provide a good check of the potential energy surface over a broad region of the configuration space. © 1998 American Institute of Physics.This work has been supported by Consejería de Educación, Cultura y Deportes del Gobierno de Canarias under Grant No. PI 2/95, DGYCIT (Spain) under Grant No. PB95- 0071, and by the European TMR network Contract No. ERBFMRX-CT96-0088.Peer Reviewe

Phase stability and dense polymorph of the BaCa(CO3)2 barytocalcite carbonate

The double carbonate BaCa(CO3)2 holds potential as host compound for carbon in the Earth?s crust and mantle. Here, we report the crystal structure determination of a high-pressure BaCa(CO3)2 phase characterized by single-crystal X-ray diffraction. This phase, named post-barytocalcite, was obtained at 5.7 GPa and can be described by a monoclinic Pm space group. The barytocalcite to post-baritocalcite phase transition involves a significant discontinuous 1.4% decrease of the unit-cell volume, and the increase of the coordination number of 1/4 and 1/2 of the Ba and Ca atoms, respectively. High-pressure powder X-ray diffraction measurements at room- and high-temperatures using synchrotron radiation and DFT calculations yield the thermal expansion of barytocalcite and, together with single-crystal data, the compressibility and anisotropy of both the low- and high-pressure phases. The calculated enthalpy differences between different BaCa(CO3)2 polymorphs confirm that barytocalcite is the thermodynamically stable phase at ambient conditions and that it undergoes the phase transition to the experimentally observed post-barytocalcite phase. The double carbonate is significantly less stable than a mixture of the CaCO3 and BaCO3 end-members above 10 GPa. The experimental observation of the high-pressure phase up to 15 GPa and 300 ºC suggests that the decomposition into its single carbonate components is kinetically hindered.Authors thank the fnancial support from the Spanish Ministerio de Ciencia e Innovación (MICINN) and the Agencia Estatal de Investigación under projects MALTA Consolider Ingenio 2010 network (RED2018-102612-T), PID2019-106383GB-C44, FIS2017-83295-P and PGC2018-097520-A-I00 (cofnanced by EU FEDER funds), and from the Generalitat Valenciana under project PROMETEO/2018/123. A.O.R. acknowledges the fnancial support of the Spanish MINECO RyC-2016-20301 Ramon y Cajal Grant. Authors also thank Dr. Nicolescu and the Mineralogy and Meteoritic Department of the Yale Peabody Museum of Natural History for providing the mineral samples, the MALTA Consolider supercomputing centre and Compute Canada for computational resources, the General Services of Research Support (SEGAI) at La Laguna University and ALBA-CELLS synchrotron for providing beamtime under experiments 2020084419 and 2021024988. Tese experiments were performed at the MSPD beamline with the collaboration of ALBA staf

Pressure-induced phase transition and band gap decrease in semiconducting β-Cu2V2O7

The understanding of the interplay between crystal structure and electronic structure in semiconductor materials is of great importance due to their potential technological applications. Pressure is an ideal external control parameter to tune the crystal structures of semiconductor materials in order to investigate their emergent piezo-electrical and optical properties. Accordingly, we investigate here the high-pressure behavior of the semiconducting antiferromagnetic material β-Cu2V2O7, finding it undergoes a pressure-induced phase transition to γ-Cu2V2O7 below 4000 atm. The pressure-induced structural and electronic evolutions are investigated by single-crystal X-ray diffraction, absorption spectroscopy and ab initio density functional theory calculations. β-Cu2V2O7 has previously been suggested as a promising photocatalyst for water splitting. Now, these new results suggest that β-Cu2V2O7 could also be of interest with regards to barocaloric effects, due to the low phase -transition pressure, in particular because it is a multiferroic material. Moreover, the phase transition involves an electronic band gap decrease of approximately 0.2 eV (from 1.93 to 1.75 eV) and a large structural volume collapse of approximately 7%.The authors acknowledge financial support from the Spanish Research Agency (AEI) and Spanish Ministry of Science and Investigation (MCIN) under projects PID2019106383GBC41/ C43/C44 (DOI: 10.13039/501100011033), and projects PGC2018-101464−B-I00 and PGC2018-097520-A-I00 (cofinanced by EU FEDER funds). The authors acknowledge financial support from the MALTA Consolider Team network, under project RED2018-102612-T. R.T. acknowledges funding from the Spanish Ministry of economy and competitiveness (MINECO) via the Juan de la Cierva Formación program (FJC2018-036185-I). J.G.P. thanks the Servicios Generales de Apoyo a la Investigación (SEGAI) at the University of La Laguna. A.L. and D.E. would like to thank the Generalitat Valenciana for the Ph.D. fellowship GRISOLIAP/2019/025, and the authors would also like to thank them for funding under the Grant Prometeo/2018/123 (EFIMAT). The authors also thank ALBA synchrotron light source for funded experiment under proposal numbers 2020074389 and 2020074398 at the MSPD-BL04 beamline

Structural, Vibrational, and Elastic Properties of Yttrium Orthoaluminate Nanoperovskite at High Pressures

"This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/page/policy/articlesonrequest/index.html."[EN] The structural and vibrational properties of nanocrystalline yttrium orthoaluminate perovskite (YAlO3) under compression have been experimentally studied. Experimental results have been compared to ab initio simulations of. bulk YAlO3, in the framework of the density functional theory. Furthermore, they have been complemented with an ab initio study of its elastic properties at different pressures. Calculated total and partial phonon density of states have allowed us to understand the contribution of the different atoms and structural units, YO12 dodecahedra and AlO6 octahedra, to the vibrational modes. The calculated infrared-active modes and their pressure dependence are also reported. Finally, the pressure dependences of the, elastic constants and the mechanical stability of the perovskite structure have been analyzed in detail, showing that this phase is mechanically stable until 92 GPa. In fact, experimental results up to 30 GPa show no evidence of any phase transition. A previously proposed possible phase transition in YAlO3 above 80 GPa is also discussed.This research was partially supported by MINECO (MAT2013-46649-C4-2/3/4-P, MAT2015-71070-REDC, and MAT2016-75586-C4-2/3/4-P) and by EU-FEDER funds. M.A.H.-R. thanks MINECO for an FPI grant (BES-2014-068666).Hernández-Rodríguez, M.; Monteseguro, V.; Lozano-Gorrín, A.; Manjón, F.; González-Platas, J.; Rodríguez-Hernández, P.; Muñoz, A.... (2017). Structural, Vibrational, and Elastic Properties of Yttrium Orthoaluminate Nanoperovskite at High Pressures. The Journal of Physical Chemistry C. 121(28):15353-15367. https://doi.org/10.1021/acs.jpcc.7b04245S15353153671212