306 research outputs found
Trispyrazolylborate Ligands Supported on Vinyl Addition Polynorbornenes and Their Copper Derivatives as Recyclable Catalysts
Polynorbornenes prepared by vinyl addition poly- merization and bearing pendant alkenyl groups serve as skeletons to support trispyrazolylborate ligands (Tpx) built at those alkenyl sites. Reaction with CuI in acetonitrile led to VA-PNB–TpxCu(NCMe) (VA-PBN = vinyl addition polynorbor- nene) with a 0.8–1.4 mmol incorporation of Cu per gram of polymer. The presence of tetracoordinated copper(I) ions was been assessed by FTIR studies on the corresponding VA-PNB-TpxCu(CO) adducts, in agreement with those on discrete TpxCu(CO). The new materials were employed as heteroge- neous catalysts in several carbene- and nitrene-transfer reac- tions, showing a behavior similar to that of the homogene- ous counterparts but also being recycled several times main- taining a high degree of activity and selectivity. This is the first example of supported Tpx ligands onto polymeric sup- ports with catalytic applications.MINECO (CTQ2017-82893-C2-1-R, CTQ2016-80913-P and Red Intecat CTQ2016-81923-REDC)Junta de Castilla y León (VA051P17, VA062G18)European Union (CHAOS COST ACTION CA-15106)
Photo-assisted ozonation of cefuroxime with solar radiation in a CPC pilot plant. kinetic parameters determination
The combination of ozone and solar radiation can be considered an effective technology as advanced oxidation process, AOP, for addressing the removal of harmful contaminants of emerging concern in water. Cefuroxime is an example of an antibiotic whose presence may result in a problem if not conveniently removed from the water. Cefuroxime oxidation has been performed employing photolytic ozonation in an autonomous pilot plant, consisting of a solar collector photo-reactor with ozone feeding, solar panel cells, and batteries for energy demands. Firstly, the kinetics of cefuroxime ozonation has been deeply studied in an agitation cell reactor. The stoichiometric ozonation ratio was estimated as zO3 = 1.00 ± 0.06 (O3 mol per cefuroxime mol) and the second-order rate constant in the range 1.50 × 106 – 4.69 × 106 M−1 s−1 for the non-dissociated and dissociated, respectively, cefuroxime molecule. The oxidation intermediates identified included hydroxylation of the initial molecule, attack to the secondary amide group and oxidation of the bi-substituted sulfide position. Secondly, the simultaneous application of ozone and solar radiation in the CPC pilot plant enhanced the degradation of cefuroxime. The kinetics in the CPC reactor was simulated and the importance of the hydroxyl radical over ozonation and photolysis was confirmed, 55% of HO• contribution. Also, over 55% of mineralization was observed during photolytic ozonation in wastewater matrix whereas single ozonation only was able to partially oxidize the initial organic content to short organic acids (formic, acetic, and oxalic) that were accumulated in the wate
Estudio del comportamiento a la combustión de diferentes tejidos como ropas protectoras.
Se realizó el Análisis Térmico Diferencial (ATD) y Termogravimétrico (TG) en atmósfera de aire a muestras de tejidos utilizadas como prendas protectoras para la extinción de incendios. Las muestras utilizadas son las siguientes:
-Muestras de tejido de algodón con tratamiento retardante a la combustión con resina ureafutfural con distintos tipos de condensación.
-Muestras de tejido de algodón blanqueadas sin tratamiento de acabado.
-Muestras de tejido Nomex.
-Muestra de tejido de algodón con tratamiento retardante a la combustión importada.
Se caracterizaron las muestras por medio de análisis físico-mecánicos y se determinó el comportamiento a la combustión por medio de la determinación de la superficie quemada.
Se pudo constatar que las muestras de tejido Nomex y las que presentan el tratamiento urea-urfural son las que más retardan el proceso de combustión.
Se estudió además la influencia del tiempo de condensación en las propiedades térmicas del tejido con el tratamiento urea-futfural llegándose a la conclusión de que a mayor tiempo de condensación de la resina se obtienen los mejores resultados.Differential Thermal Analysis and Differential Thermogravimetric Analysis were carried out in samples of fabrics, air exposed, as protecthe wear in fire extinction. Samples used were:
-Cotton fabric with a retarding treatment to combustion with urea-furfural resin and different condensation times.
-Cotton fabric bleached but without finishing treatment.
-Nomex fabric.
-Cotton fabric with a retarding agent to combustion.
Samples were characterized by physico-mechanical analysis and the behaviour to combustion was examined by determining the burnt sutface.
Nomex samples as well as samples treated with urea-furfural retard most the combustion process.
The influence of the condensation time on the thermal properties of the fabric with the urea-futfural treatment was studied, the conclusion found being that the best results are achieved with the largest condensation time.Nous avons réalisé l'Analyse Thermique Différentielle (ATD) et Thermogravimétrique (TG) atmosphere d'air sur des échantillons de tissus utilisés comme vetements protecteurs pour l'extinction d'incendies. Les échantillons utilisés sont les suivants:
-Échantillons de tissu en coton traités avec un produit qui retarde la combustion, à base de résine urée-futfural a différents taux de condensation.
-Échantillons de tissu Nomex.
-Échantillon de tissu en coton traité avec un produit qui retarde la combustion importée.
Les échantillons ont été caractérisés par des analyses physico-mécaniques et le comportement a la combustion a été mesuré en déterminant la superficie brúlée.
Nous avons pu constater que les échantillons de tissu Nomex et les échantillons soumis a un traitement urée-furfural sont ceux qui retardent le plus la combustion.
Nous avons également étudié l'influence du temps de condensaiion sur les propriétés thermiques du tissu soumis à un traitement urée-furfural et en avons conclu que plus le temps de condensation de la résine est important meilleurs sont les résultats.Peer Reviewe
Experimental and Theoretical Study of SbPO4 under Compression
This document is the Accepted Manuscript version of a Published Work that appeared in final form in
Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.inorgchem.9b02268.[EN] SbPO4 is a complex monoclinic layered material characterized by a strong activity of the nonbonding lone electron pair (LEP) of Sb. The strong cation LEP leads to the formation of layers piled up along the a axis and linked by weak SbO electrostatic interactions. In fact, Sb has 4-fold coordination with O similarly to what occurs with the P-O coordination, despite the large difference in ionic radii and electronegativity between both elements. Here we report a joint experimental and theoretical study of the structural and vibrational properties of SbPO4 at high pressure. We show that SbPO4 is not only one of the most compressible phosphates but also one of the most compressible compounds of the ABO(4) family. Moreover, it has a considerable anisotropic compression behavior, with the largest compression occurring along a direction close to the a axis and governed by the compression of the LEP and the weak interlayer Sb-O bonds. The strong compression along the a axis leads to a subtle modification of the monoclinic crystal structure above 3 GPa, leading from a 2D to a 3D material. Moreover, the onset of a reversible pressure-induced phase transition is observed above 9 GPa, which is completed above 20 GPa. We propose that the high-pressure phase is a triclinic distortion of the original monoclinic phase. The understanding of the compression mechanism of SbPO4 can aid to improve the ion intercalation and catalytic properties of this layered compound.The authors acknowledge financial support from the Brazilian Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq - 159754/2018-6, 307199/2018-5, 422250/20163, 201050/2012-9), FAPESP (2013/07793-6), Spanish Ministerio de Economia y Competitividad (MINECO) under projects MALTA Consolider Ingenio 2010 network (MAT2015-71070-REDC and RED2018-102612-T), MAT2016-75586-C4-1/2/3-P, PGC2018-097520-A-I00, FIS2017-83295-P, and PGC2018-094417-B-I00 from Generalitat Valenciana under project PROMETEO/2018/123, and the European Comission under project COMEX. D.S.-P., JA.S., and A.O.d.l.R. acknowledge "Ramim y Cajal" Fellowships for financial support (RyC-2014-15643, RYC-2015-17482, and RyC-2016-20301, respectively). E.L.d. S., A.M., A.B., and P.R-.H. acknowledge computing time provided by Red Espanola de SupercomputaciOn (RES) and MALTA-Cluster.Pereira, ALDJ.; Santamaria-Pérez, D.; Vilaplana Cerda, RI.; Errandonea, D.; Popescu, C.; Da Silva, EL.; Sans-Tresserras, JÁ.... (2020). Experimental and Theoretical Study of SbPO4 under Compression. Inorganic Chemistry. 59(1):287-307. https://doi.org/10.1021/acs.inorgchem.9b02268S287307591Falcão Filho, E. L., Bosco, C. A. C., Maciel, G. S., de Araújo, C. B., Acioli, L. H., Nalin, M., & Messaddeq, Y. (2003). Ultrafast nonlinearity of antimony polyphosphate glasses. Applied Physics Letters, 83(7), 1292-1294. doi:10.1063/1.1601679Nalin, M., Poulain, M., Poulain, M., Ribeiro, S. J. ., & Messaddeq, Y. (2001). Antimony oxide based glasses. Journal of Non-Crystalline Solids, 284(1-3), 110-116. doi:10.1016/s0022-3093(01)00388-xNalin, M., Messaddeq, Y., Ribeiro, S. J. L., Poulain, M., Briois, V., Brunklaus, G., … Eckert, H. (2004). Structural organization and thermal properties of the Sb2O3–SbPO4glass system. J. Mater. Chem., 14(23), 3398-3405. doi:10.1039/b406075jMontesso, M., Manzani, D., Donoso, J. P., Magon, C. J., Silva, I. D. A., Chiesa, M., … Nalin, M. (2018). Synthesis and structural characterization of a new SbPO4-GeO2 glass system. Journal of Non-Crystalline Solids, 500, 133-140. doi:10.1016/j.jnoncrysol.2018.07.005Wang, Y., li, L., & Li, G. (2012). One-step synthesis of SbPO4 hollow spheres by a self-sacrificed template method. RSC Advances, 2(33), 12999. doi:10.1039/c2ra21434bChen, S., Di, Y., Li, T., Li, F., & Cao, W. (2018). Impacts of ionic liquid capping on the morphology and photocatalytic performance of SbPO4 crystals. CrystEngComm, 20(30), 4305-4312. doi:10.1039/c8ce00790jSaadaoui, H., Boukhari, A., Flandrois, S., & Aride, J. (1994). Intercalation of Hydrazine and Amines in Antimony Phosphate. Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 244(1), 173-178. doi:10.1080/10587259408050100Biswal, J. B., Garje, S. S., & Revaprasadu, N. (2014). A convenient synthesis of antimony sulfide and antimony phosphate nanorods using single source dithiolatoantimony(III) dialkyldithiophosphate precursors. Polyhedron, 80, 216-222. doi:10.1016/j.poly.2014.04.017Ou, M., Ling, Y., Ma, L., Liu, Z., Luo, D., & Xu, L. (2018). Synthesis and Li-storage property of flower-like SbPO4 microspheres. Materials Letters, 224, 100-104. doi:10.1016/j.matlet.2018.04.059Jones, P. G., Sheldrick, G. M., & Schwarzmann, E. (1980). Antimony(III) arsenic(V) oxide. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 36(8), 1923-1925. doi:10.1107/s0567740880007492Kinberger, B., Danielsen, J., Haaland, A., Jerslev, B., Schäffer, C. E., Sunde, E., & Sørensen, N. A. (1970). The Crystal Structure of SbPO4. Acta Chemica Scandinavica, 24, 320-328. doi:10.3891/acta.chem.scand.24-0320Achary, S. N., Errandonea, D., Muñoz, A., Rodríguez-Hernández, P., Manjón, F. J., Krishna, P. S. R., … Tyagi, A. K. (2013). Experimental and theoretical investigations on the polymorphism and metastability of BiPO4. Dalton Transactions, 42(42), 14999. doi:10.1039/c3dt51823jAlonzo, G., Bertazzi, N., Galli, P., Marci, G., Massucci, M. A., Palmisano, L., … Saiano, F. (1998). In search of layered antimony(III) materials: synthesis and characterization of oxo-antimony(III) catecholate and further studies on antimony(III) phosphate. Materials Research Bulletin, 33(8), 1233-1240. doi:10.1016/s0025-5408(98)00095-6Alonzo, G., Bertazzi, N., Galli, P., Massucci, M. A., Patrono, P., & Saiano, F. (1998). On the synthesis and characterization of layered antimony(III) phosphate and its interaction with moist ammonia and amines. Materials Research Bulletin, 33(8), 1221-1231. doi:10.1016/s0025-5408(98)00094-4Brockner, W., & Hoyer, L. P. (2002). Synthesis and vibrational spectrum of antimony phosphate, SbPO4. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 58(9), 1911-1914. doi:10.1016/s1386-1425(01)00639-4Sudarsan, V., Muthe, K. ., Vyas, J. ., & Kulshreshtha, S. . (2002). PO43− tetrahedra in SbPO4 and SbOPO4: a 31P NMR and XPS study. Journal of Alloys and Compounds, 336(1-2), 119-123. doi:10.1016/s0925-8388(01)01888-6Errandonea, D., Gomis, O., Santamaría-Perez, D., García-Domene, B., Muñoz, A., Rodríguez-Hernández, P., … Popescu, C. (2015). Exploring the high-pressure behavior of the three known polymorphs of BiPO4: Discovery of a new polymorph. Journal of Applied Physics, 117(10), 105902. doi:10.1063/1.4914407Lacomba-Perales, R., Errandonea, D., Meng, Y., & Bettinelli, M. (2010). High-pressure stability and compressibility ofAPO4(A=La, Nd, Eu, Gd, Er, and Y) orthophosphates: An x-ray diffraction study using synchrotron radiation. Physical Review B, 81(6). doi:10.1103/physrevb.81.064113Errandonea, D., Gomis, O., Rodríguez-Hernández, P., Muñoz, A., Ruiz-Fuertes, J., Gupta, M., … Bettinelli, M. (2018). High-pressure structural and vibrational properties of monazite-type BiPO4, LaPO4, CePO4, and PrPO4. Journal of Physics: Condensed Matter, 30(6), 065401. doi:10.1088/1361-648x/aaa20dLópez-Solano, J., Rodríguez-Hernández, P., Muñoz, A., Gomis, O., Santamaría-Perez, D., Errandonea, D., … Raptis, C. (2010). Theoretical and experimental study of the structural stability ofTbPO4at high pressures. Physical Review B, 81(14). doi:10.1103/physrevb.81.144126Musselman, M. A., Wilkinson, T. M., Haberl, B., & Packard, C. E. (2018). In situ Raman spectroscopy of pressure‐induced phase transformations in polycrystalline Tb
PO
4
, Dy
PO
4
, and Gd
x
Dy
(1−
x
)
PO
4. Journal of the American Ceramic Society, 101(6), 2562-2570. doi:10.1111/jace.15374Muñoz, A., & Rodríguez-Hernández, P. (2018). High-Pressure Elastic, Vibrational and Structural Study of Monazite-Type GdPO4 from Ab Initio Simulations. Crystals, 8(5), 209. doi:10.3390/cryst8050209Ghosh, P. S., Ali, K., & Arya, A. (2018). A computational study of high pressure polymorphic transformations in monazite-type LaPO4. Physical Chemistry Chemical Physics, 20(11), 7621-7634. doi:10.1039/c7cp05587kGomis, O., Lavina, B., Rodríguez-Hernández, P., Muñoz, A., Errandonea, R., Errandonea, D., & Bettinelli, M. (2017). High-pressure structural, elastic, and thermodynamic properties of zircon-type HoPO4and TmPO4. Journal of Physics: Condensed Matter, 29(9), 095401. doi:10.1088/1361-648x/aa516aRuiz-Fuertes, J., Hirsch, A., Friedrich, A., Winkler, B., Bayarjargal, L., Morgenroth, W., … Milman, V. (2016). High-pressure phase of
LaPO4
studied by x-ray diffraction and second harmonic generation. Physical Review B, 94(13). doi:10.1103/physrevb.94.134109Stavrou, E., Tatsi, A., Raptis, C., Efthimiopoulos, I., Syassen, K., Muñoz, A., … Hanfland, M. (2012). Effects of pressure on the structure and lattice dynamics of TmPO4: Experiments and calculations. Physical Review B, 85(2). doi:10.1103/physrevb.85.024117Errandonea, D., & Garg, A. B. (2018). Recent progress on the characterization of the high-pressure behaviour of AVO4 orthovanadates. Progress in Materials Science, 97, 123-169. doi:10.1016/j.pmatsci.2018.04.004Bandiello, E., Errandonea, D., Pellicer-Porres, J., Garg, A. B., Rodriguez-Hernandez, P., Muñoz, A., … Popescu, C. (2018). Effect of High Pressure on the Crystal Structure and Vibrational Properties of Olivine-Type LiNiPO4. Inorganic Chemistry, 57(16), 10265-10276. doi:10.1021/acs.inorgchem.8b01495Achary, S. N., Bevara, S., & Tyagi, A. K. (2017). Recent progress on synthesis and structural aspects of rare-earth phosphates. Coordination Chemistry Reviews, 340, 266-297. doi:10.1016/j.ccr.2017.03.006Bykov, M., Bykova, E., Hanfland, M., Liermann, H.-P., Kremer, R. K., Glaum, R., … van Smaalen, S. (2016). High-Pressure Phase Transformations in TiPO4: A Route to Pentacoordinated Phosphorus. Angewandte Chemie International Edition, 55(48), 15053-15057. doi:10.1002/anie.201608530López-Moreno, S., & Errandonea, D. (2012). Ab initioprediction of pressure-induced structural phase transitions of CrVO4-type orthophosphates. Physical Review B, 86(10). doi:10.1103/physrevb.86.104112Errandonea, D., & Manjón, F. J. (2008). Pressure effects on the structural and electronic properties of ABX4 scintillating crystals. Progress in Materials Science, 53(4), 711-773. doi:10.1016/j.pmatsci.2008.02.001Merrill, L., & Bassett, W. A. (1974). Miniature diamond anvil pressure cell for single crystal x‐ray diffraction studies. Review of Scientific Instruments, 45(2), 290-294. doi:10.1063/1.1686607Fauth, F., Peral, I., Popescu, C., & Knapp, M. (2013). The new Material Science Powder Diffraction beamline at ALBA Synchrotron. Powder Diffraction, 28(S2), S360-S370. doi:10.1017/s0885715613000900Mao, H. K., Xu, J., & Bell, P. M. (1986). Calibration of the ruby pressure gauge to 800 kbar under quasi-hydrostatic conditions. Journal of Geophysical Research, 91(B5), 4673. doi:10.1029/jb091ib05p04673Dewaele, A., Loubeyre, P., & Mezouar, M. (2004). Equations of state of six metals above94GPa. Physical Review B, 70(9). doi:10.1103/physrevb.70.094112Prescher, C., & Prakapenka, V. B. (2015). DIOPTAS: a program for reduction of two-dimensional X-ray diffraction data and data exploration. High Pressure Research, 35(3), 223-230. doi:10.1080/08957959.2015.1059835Rodríguez-Carvajal, J. (1993). Recent advances in magnetic structure determination by neutron powder diffraction. Physica B: Condensed Matter, 192(1-2), 55-69. doi:10.1016/0921-4526(93)90108-iErrandonea, D., Muñoz, A., & Gonzalez-Platas, J. (2014). Comment on «High-pressure x-ray diffraction study of YBO3/Eu3+, GdBO3, and EuBO3: Pressure-induced amorphization in GdBO3» [J. Appl. Phys. 115, 043507 (2014)]. Journal of Applied Physics, 115(21), 216101. doi:10.1063/1.4881057Hohenberg, P., & Kohn, W. (1964). Inhomogeneous Electron Gas. Physical Review, 136(3B), B864-B871. doi:10.1103/physrev.136.b864Kresse, G., & Hafner, J. (1993). Ab initiomolecular dynamics for liquid metals. Physical Review B, 47(1), 558-561. doi:10.1103/physrevb.47.558Blöchl, P. E. (1994). Projector augmented-wave method. Physical Review B, 50(24), 17953-17979. doi:10.1103/physrevb.50.17953Perdew, J. P., Ruzsinszky, A., Csonka, G. I., Vydrov, O. A., Scuseria, G. E., Constantin, L. A., … Burke, K. (2008). Restoring the Density-Gradient Expansion for Exchange in Solids and Surfaces. Physical Review Letters, 100(13). doi:10.1103/physrevlett.100.136406Monkhorst, H. J., & Pack, J. D. (1976). Special points for Brillouin-zone integrations. Physical Review B, 13(12), 5188-5192. doi:10.1103/physrevb.13.5188Parlinski, K. Computer Code PHONON; http://wolf.ifj.edu.pl/phonon.Nielsen, O. H., & Martin, R. M. (1985). Quantum-mechanical theory of stress and force. Physical Review B, 32(6), 3780-3791. doi:10.1103/physrevb.32.3780Le Page, Y., & Saxe, P. (2002). Symmetry-general least-squares extraction of elastic data for strained materials fromab initiocalculations of stress. Physical Review B, 65(10). doi:10.1103/physrevb.65.104104Otero-de-la-Roza, A., Johnson, E. R., & Luaña, V. (2014). Critic2: A program for real-space analysis of quantum chemical interactions in solids. Computer Physics Communications, 185(3), 1007-1018. doi:10.1016/j.cpc.2013.10.026Dewhurst, K.; Sharma, S.; Nordström, L.; Cricchio, F.; Grånäs, O.; Gross, H.; Ambrosch-Draxl, C.; Persson, C.; Bultmark, F.; Brouder, C., The Elk FP-LAPW code; http://elk.sourceforge.net/ (accessed Oct 31, 2019).Manjón, F. J., Vilaplana, R., Gomis, O., Pérez-González, E., Santamaría-Pérez, D., Marín-Borrás, V., … Muñoz-Sanjosé, V. (2013). High-pressure studies of topological insulators Bi2Se3, Bi2Te3, and Sb2Te3. physica status solidi (b), 250(4), 669-676. doi:10.1002/pssb.201200672Pereira, A. L. J., Errandonea, D., Beltrán, A., Gracia, L., Gomis, O., Sans, J. A., … Popescu, C. (2013). Structural study of α-Bi2O3under pressure. Journal of Physics: Condensed Matter, 25(47), 475402. doi:10.1088/0953-8984/25/47/475402Pereira, A. L. J., Gomis, O., Sans, J. A., Pellicer-Porres, J., Manjón, F. J., Beltran, A., … Muñoz, A. (2014). Pressure effects on the vibrational properties ofα-Bi2O3: an experimental and theoretical study. Journal of Physics: Condensed Matter, 26(22), 225401. doi:10.1088/0953-8984/26/22/225401Pereira, A. L. J., Sans, J. A., Vilaplana, R., Gomis, O., Manjón, F. J., Rodríguez-Hernández, P., … Beltrán, A. (2014). Isostructural Second-Order Phase Transition of β-Bi2O3 at High Pressures: An Experimental and Theoretical Study. The Journal of Physical Chemistry C, 118(40), 23189-23201. doi:10.1021/jp507826jIbáñez, J., Sans, J. A., Popescu, C., López-Vidrier, J., Elvira-Betanzos, J. J., Cuenca-Gotor, V. P., … Muñoz, A. (2016). Structural, Vibrational, and Electronic Study of Sb2S3 at High Pressure. The Journal of Physical Chemistry C, 120(19), 10547-10558. doi:10.1021/acs.jpcc.6b01276Kroumova, E., Aroyo, M. I., Perez-Mato, J. M., Kirov, A., Capillas, C., Ivantchev, S., & Wondratschek, H. (2003). Bilbao Crystallographic Server : Useful Databases and Tools for Phase-Transition Studies. Phase Transitions, 76(1-2), 155-170. doi:10.1080/0141159031000076110Canepa, P., Hanson, R. M., Ugliengo, P., & Alfredsson, M. (2010). J-ICE: a newJmolinterface for handling and visualizing crystallographic and electronic properties. Journal of Applied Crystallography, 44(1), 225-229. doi:10.1107/s0021889810049411Sans, J. A., Manjón, F. J., Pereira, A. L. J., Vilaplana, R., Gomis, O., Segura, A., … Ruleova, P. (2016). Structural, vibrational, and electrical study of compressed BiTeBr. Physical Review B, 93(2). doi:10.1103/physrevb.93.024110Pereira, A. L. J., Santamaría-Pérez, D., Ruiz-Fuertes, J., Manjón, F. J., Cuenca-Gotor, V. P., Vilaplana, R., … Sans, J. A. (2018). Experimental and Theoretical Study of Bi2O2Se Under Compression. The Journal of Physical Chemistry C, 122(16), 8853-8867. doi:10.1021/acs.jpcc.8b02194Bai, Y., Srikanth, N., Chua, C. K., & Zhou, K. (2017). Density Functional Theory Study of Mn+1AXn Phases: A Review. Critical Reviews in Solid State and Materials Sciences, 44(1), 56-107. doi:10.1080/10408436.2017.1370577An ab initio study on compressibility of Al-containing MAX-phase carbides. (2013). Journal of Applied Physics, 114(17), 173709. doi:10.1063/1.4829282Bai, Y., Qi, X., He, X., Sun, D., Kong, F., Zheng, Y., … Duff, A. I. (2018). Phase stability and weak metallic bonding within ternary‐layered borides CrAlB, Cr
2
AlB
2
, Cr
3
AlB
4
, and Cr
4
AlB
6. Journal of the American Ceramic Society, 102(6), 3715-3727. doi:10.1111/jace.16206Birch, F. (1978). Finite strain isotherm and velocities for single-crystal and polycrystalline NaCl at high pressures and 300°K. Journal of Geophysical Research, 83(B3), 1257. doi:10.1029/jb083ib03p01257Pereira, A. L. J., Gomis, O., Sans, J. A., Contreras-García, J., Manjón, F. J., Rodríguez-Hernández, P., … Beltrán, A. (2016). β−Bi2O3under compression: Optical and elastic properties and electron density topology analysis. Physical Review B, 93(22). doi:10.1103/physrevb.93.224111Cuenca-Gotor, V. P., Sans, J. A., Ibáñez, J., Popescu, C., Gomis, O., Vilaplana, R., … Bergara, A. (2016). Structural, Vibrational, and Electronic Study of α-As2Te3 under Compression. The Journal of Physical Chemistry C, 120(34), 19340-19352. doi:10.1021/acs.jpcc.6b06049Korabel’nikov, D. V., & Zhuravlev, Y. N. (2018). Structural, elastic, electronic and vibrational properties of a series of sulfates from first principles calculations. Journal of Physics and Chemistry of Solids, 119, 114-121. doi:10.1016/j.jpcs.2018.03.037Santamaría-Pérez, D., Gracia, L., Garbarino, G., Beltrán, A., Chuliá-Jordán, R., Gomis, O., … Segura, A. (2011). High-pressure study of the behavior of mineral barite by x-ray diffraction. Physical Review B, 84(5). doi:10.1103/physrevb.84.054102Santamaria-Perez, D., Chulia-Jordan, R., Daisenberger, D., Rodriguez-Hernandez, P., & Muñoz, A. (2019). Dense Post-Barite-type Polymorph of PbSO4 Anglesite at High Pressures. Inorganic Chemistry, 58(4), 2708-2716. doi:10.1021/acs.inorgchem.8b03254Hinrichsen, B., Dinnebier, R. E., Liu, H., & Jansen, M. (2008). The high pressure crystal structures of tin sulphate: a case study for maximal information recovery from 2D powder diffraction data. Zeitschrift für Kristallographie - Crystalline Materials, 223(3), 195-203. doi:10.1524/zkri.2008.0017Knight, K. S. (2010). Analytical expressions to determine the isothermal compressibility tensor and the isobaric thermal expansion tensor for monoclinic crystals: application to determine the direction of maximum compressibility in jadeite. Physics and Chemistry of Minerals, 37(8), 529-533. doi:10.1007/s00269-009-0353-8Angel, R. J. Win_Strain; http://www.rossangel.com/text_strain.htm.Errandonea, D., Muñoz, A., Rodríguez-Hernández, P., Gomis, O., Achary, S. N., Popescu, C., … Tyagi, A. K. (2016). High-Pressure Crystal Structure, Lattice Vibrations, and Band Structure of BiSbO4. Inorganic Chemistry, 55(10), 4958-4969. doi:10.1021/acs.inorgchem.6b00503Bodenstein, D., Brehm, A., Jones, P. G., Schwarzmann, E., & Sheldrick, G. M. (1982). Darstellung und Kristallstruktur von Arsen(III)phosplior(V)oxid, AsPO4 / Preparation and Crystal Structure of Arsenic(III) Phosphorus(V) Oxide, AsPO4. Zeitschrift für Naturforschung B, 37(2), 136-137. doi:10.1515/znb-1982-0203Ruiz-Fuertes, J., Friedrich, A., Gomis, O., Errandonea, D., Morgenroth, W., Sans, J. A., & Santamaría-Pérez, D. (2015). High-pressure structural phase transition inMnWO4. Physical Review B, 91(10). doi:10.1103/physrevb.91.104109Garg, A. B., Errandonea, D., Rodríguez-Hernández, P., & Muñoz, A. (2016). ScVO4under non-hydrostatic compression: a new metastable polymorph. Journal of Physics: Condensed Matter, 29(5), 055401. doi:10.1088/1361-648x/29/5/055401Momma, K., & Izumi, F. (2011). VESTA 3for three-dimensional visualization of crystal, volumetric and morphology data. Journal of Applied Crystallography, 44(6), 1272-1276. doi:10.1107/s0021889811038970Hoppe, R. (1970). The Coordination Number– an«Inorganic Chameleon». Angewandte Chemie International Edition in English, 9(1), 25-34. doi:10.1002/anie.197000251Hoppe, R. (1979). Effective coordination numbers (ECoN) and mean fictive ionic radii (MEFIR). Zeitschrift für Kristallographie - Crystalline Materials, 150(1-4), 23-52. doi:10.1524/zkri.1979.150.14.23Baur, W. H. (1974). The geometry of polyhedral distortions. Predictive relationships for the phosphate group. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 30(5), 1195-1215. doi:10.1107/s0567740874004560Guńka, P. A., & Zachara, J. (2019). Towards a quantitative bond valence description of coordination spheres – the concepts of valence entropy and valence diversity coordination numbers. Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials, 75(1), 86-96. doi:10.1107/s2052520618017833Ruiz-Fuertes, J., Segura, A., Rodríguez, F., Errandonea, D., & Sanz-Ortiz, M. N. (2012). An
Financiamiento no formal para el emprendimiento de una pyme (pequeña y mediana empresa)
The aim of the research work is to identify the types of financing different from banking and suitable for a SME. When undertaking a business, it is necessary to collect as much information as possible about the adequate financing, based on the needs and payment capacity of each entrepreneur; he should know that there's not only exist financial support opportunities from bank entities, he can look for other alternatives. It was identified that the most used and reliable type of non-formal financing are the “Juntas” or “Panderos” that allows the entrepreneur to don't depend on banking entities.El objetivo del trabajo de investigación es identificar los tipos de financiamiento diferente al bancario y adecuado para una PYME. Al emprender un negocio es necesario recaudar la mayor información posible acerca del financiamiento adecuado, basado en las necesidades y capacidad de pago de cada emprendedor; éste debe conocer que no solo existen las oportunidades de apoyo financiero de entidades bancarias, puede buscar otras alternativas Se identificó que el tipo de financiamiento no formal más utilizado y confiable es el de las juntas o panderos que permiten al emprendedor no depender de entidades bancarias
Teleconsulta odontológica en tiempo del COVID-19. Revisión literaria
The high transmissibility of the etiological agent SARS-CoV-2, led the dentist to be the health professional with the highest risk of contagion due to the face-to-face consultation where he is in contact with saliva and blood in addition to the use of aerosols. This has led to the use of technology and telecommunications as a tool for a remote consultation, being known as Teleodontology. The search criteria for scientific articles in electronic format have been based on publication time, presence of DOI, no language is excluded; obtained from sources such as PubMed, SciElo, Google Scholar. Carrying out the search in July 2020. In Peru, 70% of infections in dentists were during the face-to-face consultation, the legal and ethical aspect leads to distrust of carrying out a teleconsultation. This research work provides recommendations from the reason for consultation, informed consent, prescription, patient follow-up, as well as the tele-education approach. CONCLUSIONS: Teleodontology is one of the first options to provide consultation in cases that do not require a face-to-face consultation, however, the lack of a protocol, supporting laws and training has led to distrust in carrying it out. La alta transmisibilidad del agente etiológico SARS-CoV-2, llevo al odontólogo a ser el profesional de la salud en presentar mayor riesgo de contagio debido a la consulta presencial donde se encuentra en contacto con saliva y sangre además del uso de aerosoles. Esto ha llevado al uso de la tecnología y telecomunicaciones como herramienta para una consulta no presencial, siendo conocida como Teleodontología. MÉTODOS: Los criterios de búsqueda para artículos científicos en formato electrónico han sido basados en tiempo de publicación, presencia de DOI, no se excluye ningún idioma; obtenidos de fuentes como PubMed, SciElo, Google Académico. Realizando la búsqueda en julio 2020. DESARROLLO: En el Perú, el 70% de contagios en odontólogos fue durante la consulta presencial, el aspecto legal y ético lleva a la desconfianza de efectuar una teleconsulta. El presente trabajo de investigación brinda recomendaciones desde el motivo de consulta, consentimiento informado, prescripción, seguimiento al paciente además del enfoque de la teleeducación. CONCLUSIONES: La teleodontología es una de las primeras opciones para brindar consulta en casos que no requieran una consulta presencial, sin embargo, la falta de un protocolo, leyes que lo avalen y adiestramiento ha llevado a generar desconfianza en efectuarla.
ANÁLISIS DE LAS VENTAJAS Y DESVENTAJAS DE DOS PAQUETES DE CÓMPUTO, EMPLEANDO COMO CASO DE ESTUDIO UN PROCESO DE FABRICACIÓN DE TABICÓN (ANALYSIS OF THE ADVANTAGES AND DISADVANTAGES OF TWO COMPUTER PACKAGES, USING A TABICON MANUFACTURING PROCESS AS A CASE STUDY)
Resumen
En el presente documento se realiza el análisis comparativo entre dos softwares de simulación, continuo y discreto, de un sistema de producción de tabicón ligero. A partir del tiempo estándar de cada una de las etapas del proceso, se definieron las variables y elementos necesarios para realizar los modelos de simulación. El análisis con el software Vensim (continuo) involucra ecuaciones matemáticas que reflejan el flujo de los materiales durante cada etapa, y con el sofware FlexSim (discreto), se obtuvieron resultados visuales además de gráficos estadísticos del proceso. En ambos modelos se evaluaron indicadores claves del proceso, como capacidad de producción, tiempos de entrega e inventario. Esto permitió demostrar que, al establecer adecuadamente las variables y parámetros, ambos softwares resultan ser una herramienta útil para la representación del proceso. Se pretende que este estudio sirva de apoyo, para comprender las ventajas y desventajas al realizar simulaciones mediante análisis continuo y discreto.
Palabras clave: FlexSim, inventario en proceso, sistema push, Vensim.
Abstract
In this document, the comparative analysis between two simulation software, continuous and discrete, of a light partition production system. Starting from the standard time of each of the stages of the process, the variables and elements necessary to realice the simulation models were defined. The analysis with the Vensim software (continuous) involves mathematical equations that reflect the flow of the materials during each stage, and with the FlexSim software (discrete), visual results were obtained in addition to statistical graphics of the process. In both models, key indicators of the process were evaluated, such as production capacity, delivery times and inventory. This made it possible to demonstrate that, by properly setting the variables and parameters, both softwares turn out to be a useful tool for the representation of the process. This study is intended to provide support in understanding the advantages and disadvantages of performing simulations using continuous and discrete analysis
Keywords: FlexSim, push system, Vensim, work in process
A genome-wide association study follow-up suggests a possible role for PPARG in systemic sclerosis susceptibility
Introduction:
A recent genome-wide association study (GWAS) comprising a French cohort of systemic sclerosis (SSc) reported several non-HLA single-nucleotide polymorphisms (SNPs) showing a nominal association in the discovery phase. We aimed to identify previously overlooked susceptibility variants by using a follow-up strategy.<p></p>
Methods:
Sixty-six non-HLA SNPs showing a P value <10-4 in the discovery phase of the French SSc GWAS were analyzed in the first step of this study, performing a meta-analysis that combined data from the two published SSc GWASs. A total of 2,921 SSc patients and 6,963 healthy controls were included in this first phase. Two SNPs, PPARG rs310746 and CHRNA9 rs6832151, were selected for genotyping in the replication cohort (1,068 SSc patients and 6,762 healthy controls) based on the results of the first step. Genotyping was performed by using TaqMan SNP genotyping assays.
Results:
We observed nominal associations for both PPARG rs310746 (PMH = 1.90 × 10-6, OR, 1.28) and CHRNA9 rs6832151 (PMH = 4.30 × 10-6, OR, 1.17) genetic variants with SSc in the first step of our study. In the replication phase, we observed a trend of association for PPARG rs310746 (P value = 0.066; OR, 1.17). The combined overall Mantel-Haenszel meta-analysis of all the cohorts included in the present study revealed that PPARG rs310746 remained associated with SSc with a nominal non-genome-wide significant P value (PMH = 5.00 × 10-7; OR, 1.25). No evidence of association was observed for CHRNA9 rs6832151 either in the replication phase or in the overall pooled analysis.<p></p>
Conclusion:
Our results suggest a role of PPARG gene in the development of SSc
Structure and tree diversity of secondary dry tropical forests in the Sierra de Huautla Biosphere Reserve, Morelos
"Se estudió la recuperación en riqueza, composición, estructura y diversidad arbórea en 3 condiciones de bosque tropical caducifolio secundario con diferente tiempo de abandono (C35, C45 y C65 años) en el sureste del estado de Morelos. En cada condición se establecieron 3 unidades de muestreo de 50 × 50 m (2,500 m2) y se midieron a todos los individuos ≥ 2.5 cm de diámetro normal (DN). En total se registraron 2,791 individuos, pertenecientes a 79 especies, 53 géneros y 30 familias. Fabaceae fue la familia con el mayor número de especies e individuos. C45 presentó la mayor riqueza de especies (57), seguida de C35 (48) y C65 (43). Las condiciones fueron diferentes (p < 0.0001) en área basal, altura total, DN y cobertura de copa. Las especies con mayores índices relativos de valor de importancia (IVIR) y de valor forestal (IVFR) fueron Pachycereus grandis (IVIR = 22.6, IVFR = 28.7), Amphipterygium adstringens (IVIR = 20.9, IVFR = 17.0), Lysiloma divaricatum (IVIR = 11.2, IVFR = 18.9) y Quercus glaucoides (IVIR = 10.5, IVFR = 13.1). Se encontraron diferencias altamente significativas (p < 0.001) entre condiciones de abandono para la heterogeneidad (Shannon-Wiener: H´), y valores significativamente (p < 0.05) mayores en C65 para el recíproco de Simpson (1/D), así como en C35 y C45 para los índices de Margalef (DMG) y α de Fisher (S). La semejanza florística (Sorensen: Is) fue máxima entre condiciones con menor tiempo de abandono (72%) y mínima con la condición de mayor tiempo (54%). El procedimiento de permutación de respuesta múltiple indicó diferencias significativas (p
< 0.05) en la composición de especies entre condiciones tempranas (C35 y C45) y tardías (C65). Estos resultados explican el proceso de la sucesión secundaria en los bosques tropicales caducifolios del área de estudio y dan elementos para efectuar una mejor planificación de las actividades conducentes a su conservación.""The recovery in richness, composition, structure and tree diversity was studied in three conditions of secondary
tropical deciduous forest with different time of abandonment (C35, C45 and C65 years) in the southeast of the state
of Morelos. In each condition, three plots of 50 × 50 m (2,500 m2) were established and all individuals ≥ 2.5 cm of
normal diameter (ND) were measured. In total, 2,791 individuals belonging to 79 species, 53 genera and 30 families
were registered. Fabaceae was the family with the largest number of species and individuals. C45 had the highest
species richness (57), followed by C35 (48) and C65 (43). The conditions were different (p < 0.0001) in basal area,
total height, ND and crown coverage. The species with the highest relative value of importance (IVIR) and forest value
(IVFR) were Pachycereus grandis (IVIR = 22.6, IVFR = 28.7), Amphipterygium adstringens (IVIR = 20.9, IVFR =
17.0), Lysiloma divaricatum (IVIR =11.2, IVFR = 18.9) and Quercus glaucoides (IVIR = 10.5, IVFR = 13.1). High
significant differences (p < 0.001) between abandonment conditions were found for heterogeneity (Shannon-Wiener:
H’), and highest significant values (p < 0.05) for Simpson reciprocal index (1/D) in C65, as well as to Margalef (DMG)
and Fisher’s α (S) indexes in C35 and C45. The floristic similarity (Sorensen: Is) was highest among conditions with
less time of abandonment (72%) and minimum with the condition of greater time (54%). The multiple response
permutation procedure indicated significant differences (p < 0.05) in the species composition between early (C35 and
C45) and late (C65) conditions. These results explain the process of secondary succession in the tropical deciduous
forests of the study area and provide elements for improve planning of the activities leading to its conservation.
- …