Can optical spectroscopy directly elucidate the ground state of C20?

The optical response of the lowest energy members of the C20 family is calculated using time-dependent density functional theory within a real-space, real-time scheme. Significant differences are found among the spectra of the different isomers, and thus we propose optical spectroscopy as a tool for experimental investigation of the structure of these important clusters.Comment: 11 pages, 2 figures. To be published in J. Chem. Phy

Driving the Crystallization of Zeolites

[EN] The synthesis of zeolites with new structures and/or improved properties heavily relies on trial and error efforts that are not entirely blind, as the large empirical background accumulated for the last 7 decades can be, to some extent, rationalized and purposefully used to make new materials. The so-called structure-directing factors may be combined to promote (or frustrate) the crystallization of a particular structure. This personal account opens with the concept of geoinspiration, as suggested by Prof. Ruiz-Hitzky, and its application to zeolite synthesis. We then provide a concise overview of structure-direction in the synthesis of zeolites and detail examples, both new and from the literature, on how they can be combined to drive the crystallization towards (or away from) structures displaying particular features.Financial support by the Spanish Ministry of Economy and Competitiveness (MAT2015-71117-R and AGL2015-70235-C2-R) is acknowledged. P. L. is grateful to the China Scholarship Council (CSC) for a fellowship and to the Dalian Institute of Chemical Physics for permission to leave. Thanks are also due to Wikimedia Commons and Mr. A. T. Chang for the picture of the hot springs included in the frontispiece.Lu, P.; Villaescusa Alonso, LA.; Camblor, MA. (2018). Driving the Crystallization of Zeolites. The Chemical Record. 18(7-8):713-723. https://doi.org/10.1002/tcr.201700092S713723187-8Porous Materials 2011Cundy, C. S., & Cox, P. A. (2003). The Hydrothermal Synthesis of Zeolites:  History and Development from the Earliest Days to the Present Time. Chemical Reviews, 103(3), 663-702. doi:10.1021/cr020060iBarrer, R. M. (1948). 33. Synthesis of a zeolitic mineral with chabazite-like sorptive properties. Journal of the Chemical Society (Resumed), 127. doi:10.1039/jr9480000127Rees, L. V. C. (1998). Richard Maling Barrer. 16 June 1910–12 September 1996. Biographical Memoirs of Fellows of the Royal Society, 44, 37-49. doi:10.1098/rsbm.1998.0003Breck, D. W., Eversole, W. G., & Milton, R. M. (1956). NEW SYNTHETIC CRYSTALLINE ZEOLITES. Journal of the American Chemical Society, 78(10), 2338-2339. doi:10.1021/ja01591a082Rabo, J. A., & Schoonover, M. W. (2001). Early discoveries in zeolite chemistry and catalysis at Union Carbide, and follow-up in industrial catalysis. Applied Catalysis A: General, 222(1-2), 261-275. doi:10.1016/s0926-860x(01)00840-7Piccione, P. M., Laberty, C., Yang, S., Camblor, M. A., Navrotsky, A., & Davis, M. E. (2000). Thermochemistry of Pure-Silica Zeolites. The Journal of Physical Chemistry B, 104(43), 10001-10011. doi:10.1021/jp002148aBarrer, R. M., & Denny, P. J. (1961). 201. Hydrothermal chemistry of the silicates. Part IX. Nitrogenous aluminosilicates. Journal of the Chemical Society (Resumed), 971. doi:10.1039/jr9610000971Kerr, G. T., & Kokotailo, G. T. (1961). SODIUM ZEOLITE ZK-4, A NEW SYNTHETIC CRYSTALLINE ALUMINOSILICATE. Journal of the American Chemical Society, 83(22), 4675-4675. doi:10.1021/ja01483a052Kerr, G. T. (1966). Chemistry of Crystalline Aluminosilicates. II. The Synthesis and Properties of Zeolite ZK-4. Inorganic Chemistry, 5(9), 1537-1539. doi:10.1021/ic50043a015Lawton, S. L., & Rohrbaugh, W. J. (1990). The Framework Topology of ZSM-18, a Novel Zeolite Containing Rings of Three (Si,Al)-O Species. Science, 247(4948), 1319-1322. doi:10.1126/science.247.4948.1319Koelmel, C. M., Li, Y. S., Freeman, C. M., Levine, S. M., Hwang, M.-J., Maple, J. R., & Newsam, J. M. (1994). Quantum and Molecular Mechanics Study of the Tris(Quaternary Ammonium) Cation Used as the Zeolite ZSM-18 Synthesis Template. The Journal of Physical Chemistry, 98(49), 12911-12918. doi:10.1021/j100100a017Gies, H., & Marker, B. (1992). The structure-controlling role of organic templates for the synthesis of porosils in the systems SiO2/template/H2O. Zeolites, 12(1), 42-49. doi:10.1016/0144-2449(92)90008-dMoini, A., Schmitt, K. D., Valyocsik, E. W., & Polomski, R. F. (1994). The role of diquaternary cations as directing agents in zeolite synthesis. Zeolites, 14(7), 504-511. doi:10.1016/0144-2449(94)90182-1Struct. BondLee, S.-H., Shin, C.-H., Yang, D.-K., Ahn, S.-D., Nam, I.-S., & Hong, S. B. (2004). Reinvestigation into the synthesis of zeolites using diquaternary alkylammonium ions (CH3)3N+(CH2)nN+(CH3)3 with n=3–10 as structure-directing agents. Microporous and Mesoporous Materials, 68(1-3), 97-104. doi:10.1016/j.micromeso.2003.12.011Hong, S. B., Min, H.-K., Shin, C.-H., Cox, P. A., Warrender, S. J., & Wright, P. A. (2007). Synthesis, Crystal Structure, Characterization, and Catalytic Properties of TNU-9. Journal of the American Chemical Society, 129(35), 10870-10885. doi:10.1021/ja073109gHydrothermal Chemistry of Zeolites 1982Hay, R. L., & Sheppard, R. A. (2001). Occurrence of Zeolites in Sedimentary Rocks: An Overview. Reviews in Mineralogy and Geochemistry, 45(1), 217-234. doi:10.2138/rmg.2001.45.6Camblor, M. A., Villaescusa, L. A., & Díaz‐Cabañas, M. J. (1999). Topics in Catalysis, 9(1/2), 59-76. doi:10.1023/a:1019154304344Caullet, P., Paillaud, J.-L., Simon-Masseron, A., Soulard, M., & Patarin, J. (2005). The fluoride route: a strategy to crystalline porous materials. Comptes Rendus Chimie, 8(3-4), 245-266. doi:10.1016/j.crci.2005.02.001Koller, H., Lobo, R. F., Burkett, S. L., & Davis, M. E. (1995). SiO-.cntdot. .cntdot. .cntdot.HOSi Hydrogen Bonds in As-Synthesized High-Silica Zeolites. The Journal of Physical Chemistry, 99(33), 12588-12596. doi:10.1021/j100033a036Chézeau, J.-M., Delmotte, L., Guth, J.-L., & Soulard, M. (1989). High-resolution solid-state 29Si and 13C n.m.r. on highly siliceous MFI-type zeolites synthesized in nonalkaline fluoride medium. Zeolites, 9(1), 78-80. doi:10.1016/0144-2449(89)90013-4Blasco, T., Camblor, M. A., Corma, A., Esteve, P., Guil, J. M., Martínez, A., … Valencia, S. (1998). Direct Synthesis and Characterization of Hydrophobic Aluminum-Free Ti−Beta Zeolite. The Journal of Physical Chemistry B, 102(1), 75-88. doi:10.1021/jp973288wGUTH, J. L., KESSLER, H., CAULLET, P., HAZM, J., MERROUCHE, A., & PATARIN, J. (1993). F-: A MULTIFUNCTIONAL TOOL FOR MICROPOROUS SOLIDS a) MINERALIZING, STRUCTURE DIRECTING AND TEMPLATING EFFECTS IN THE SYNTHESIS. Proceedings from the Ninth International Zeolite Conference, 215-222. doi:10.1016/b978-1-4832-8383-8.50024-6Zicovich-Wilson, C. M., San-Román, M. L., Camblor, M. A., Pascale, F., & Durand-Niconoff, J. S. (2007). Structure, Vibrational Analysis, and Insights into Host−Guest Interactions in As-Synthesized Pure Silica ITQ-12 Zeolite by Periodic B3LYP Calculations. Journal of the American Chemical Society, 129(37), 11512-11523. doi:10.1021/ja0730361Zicovich-Wilson, C. M., Gándara, F., Monge, A., & Camblor, M. A. (2010). In SituTransformation of TON Silica Zeolite into the Less Dense ITW: Structure-Direction Overcoming Framework Instability in the Synthesis of SiO2Zeolites. Journal of the American Chemical Society, 132(10), 3461-3471. doi:10.1021/ja9094318Rojas, A., Martínez-Morales, E., Zicovich-Wilson, C. M., & Camblor, M. A. (2012). Zeolite Synthesis in Fluoride Media: Structure Direction toward ITW by Small Methylimidazolium Cations. Journal of the American Chemical Society, 134(4), 2255-2263. doi:10.1021/ja209832yRojas, A., San-Roman, M. L., Zicovich-Wilson, C. M., & Camblor, M. A. (2013). Host–Guest Stabilization of a Zeolite Strained Framework: In Situ Transformation of Zeolite MTW into the Less Dense and More Strained ITW. Chemistry of Materials, 25(5), 729-738. doi:10.1021/cm303709eVillaescusa, L. A., Barrett, P. A., & Camblor, M. A. (1998). Calcination of Octadecasil:  Fluoride Removal and Symmetry of the Pure SiO2Host. Chemistry of Materials, 10(12), 3966-3973. doi:10.1021/cm9804113Camblor, M. A., Corma, A., & Valencia, S. (1996). Spontaneous nucleation and growth of pure silica zeolite-? free of connectivity defects. Chemical Communications, (20), 2365. doi:10.1039/cc9960002365Camblor, M. A., Corma, A., Lightfoot, P., Villaescusa, L. A., & Wright, P. A. (1997). Synthesis and Structure of ITQ-3, the First Pure Silica Polymorph with a Two-Dimensional System of Straight Eight-Ring Channels. Angewandte Chemie International Edition in English, 36(23), 2659-2661. doi:10.1002/anie.199726591Barrett, P. A., Camblor, M. A., Corma, A., Jones, R. H., & Villaescusa, L. A. (1997). Structure of ITQ-4, a New Pure Silica Polymorph Containing Large Pores and a Large Void Volume. Chemistry of Materials, 9(8), 1713-1715. doi:10.1021/cm970173wBarrer, R. M., & Baynham, J. W. (1956). 562. The hydrothermal chemistry of the silicates. Part VII. Synthetic potassium aluminosilicates. Journal of the Chemical Society (Resumed), 2882. doi:10.1039/jr9560002882Díaz-Cabañas, M.-J., & Barrett, P. A. (1998). Synthesis and structure of pure SiO2 chabazite: the SiO2 polymorph with the lowest framework density. Chemical Communications, (17), 1881-1882. doi:10.1039/a804800bVillaescusa, L. A., Barrett, P. A., & Camblor, M. A. (1998). Synthesis and structure of ITQ-9: a new microporous SiO2 polymorph. Chemical Communications, (21), 2329-2330. doi:10.1039/a806696eVillaescusa, L. A., Barrett, P. A., & Camblor, M. A. (1999). ITQ-7: A New Pure Silica Polymorph with a Three-Dimensional System of Large Pore Channels. Angewandte Chemie International Edition, 38(13-14), 1997-2000. doi:10.1002/(sici)1521-3773(19990712)38:13/143.0.co;2-uBarrett, P. A., Boix, T., Puche, M., Olson, D. H., Jordan, E., Koller, H., & Camblor, M. A. (2003). ITQ-12: a new microporous silica polymorph potentially useful for light hydrocarbon separationsElectronic supplementary information (ESI) available: details of the structure solution, Rietveld refinements in space groups C2/m and Cm and energy minimisation calculations in C2/m, Cm and C2. See http://www.rsc.org/suppdata/cc/b3/b306440a/. Chemical Communications, (17), 2114. doi:10.1039/b306440aBarrett, P. A., Díaz-Cabañas, M.-J., & Camblor, M. A. (1999). Crystal Structure of Zeolite MCM-35 (MTF). Chemistry of Materials, 11(10), 2919-2927. doi:10.1021/cm9910660PhD Thesis 1997Liu, Z., Ohsuna, T., Terasaki, O., Camblor, M. A., Diaz-Cabañas, M.-J., & Hiraga, K. (2001). The First Zeolite with Three-Dimensional Intersecting Straight-Channel System of 12-Membered Rings. Journal of the American Chemical Society, 123(22), 5370-5371. doi:10.1021/ja0107778Tang, L., Shi, L., Bonneau, C., Sun, J., Yue, H., Ojuva, A., … Zou, X. (2008). A zeolite family with chiral and achiral structures built from the same building layer. Nature Materials, 7(5), 381-385. doi:10.1038/nmat2169Rojas, A., & Camblor, M. A. (2012). A Pure Silica Chiral Polymorph with Helical Pores. Angewandte Chemie International Edition, 51(16), 3854-3856. doi:10.1002/anie.201108753Smith, J. V., Pluth, J. J., & Andries, K. J. (1993). The framework topology of magnesiumaluminophosphate structure type 36. Zeolites, 13(3), 166-169. doi:10.1016/s0144-2449(05)80273-8Burton, A., Darton, R. J., Davis, M. E., Hwang, S.-J., Morris, R. E., Ogino, I., & Zones, S. I. (2006). Structure-Directing Agent Location and Non-Centrosymmetric Structure of Fluoride-Containing Zeolite SSZ-55. The Journal of Physical Chemistry B, 110(11), 5273-5278. doi:10.1021/jp054950oMoliner, M., González, J., Portilla, M. T., Willhammar, T., Rey, F., Llopis, F. J., … Corma, A. (2011). A New Aluminosilicate Molecular Sieve with a System of Pores between Those of ZSM-5 and Beta Zeolite. Journal of the American Chemical Society, 133(24), 9497-9505. doi:10.1021/ja2015394Corma, A., Rey, F., Rius, J., Sabater, M. J., & Valencia, S. (2004). Supramolecular self-assembled molecules as organic directing agent for synthesis of zeolites. Nature, 431(7006), 287-290. doi:10.1038/nature02909Vortmann, S., Marler, B., Gies, H., & Daniels, P. (1995). Synthesis and crystal structure of the new borosilicate zeolite RUB-13. Microporous Materials, 4(2-3), 111-121. doi:10.1016/0927-6513(94)00090-iLee, G. (2002). Polymethylated [4.1.1] Octanes Leading to Zeolite SSZ-50. Journal of Solid State Chemistry, 167(2), 289-298. doi:10.1016/s0022-4596(02)99549-6Shannon, M. D., Casci, J. L., Cox, P. A., & Andrews, S. J. (1991). Structure of the two-dimensional medium-pore high-silica zeolite NU-87. Nature, 353(6343), 417-420. doi:10.1038/353417a0Zones, S. I., Hwang, S.-J., Elomari, S., Ogino, I., Davis, M. E., & Burton, A. W. (2005). The fluoride-based route to all-silica molecular sieves; a strategy for synthesis of new materials based upon close-packing of guest–host products. Comptes Rendus Chimie, 8(3-4), 267-282. doi:10.1016/j.crci.2004.12.009Briscoe, N. A., Johnson, D. W., Shannon, M. D., Kokotailo, G. T., & McCusker, L. B. (1988). The framework topology of zeolite EU-1. Zeolites, 8(1), 74-76. doi:10.1016/s0144-2449(88)80033-2PhD Thesis 1999Arranz, M., Pérez-Pariente, J., Wright, P. A., Slawin, A. M. Z., Blasco, T., Gómez-Hortigüela, L., & Corà, F. (2005). Cooperative Structure-Directing Effect of Fluorine-Containing Organic Molecules and Fluoride Anions in the Synthesis of Zeolites. Chemistry of Materials, 17(17), 4374-4385. doi:10.1021/cm050971jLobo, R. F., Pan, M., Chan, I., Li, H.-X., Medrud, R. C., Zones, S. I., … Davis, M. E. (1993). SSZ-26 and SSZ-33: Two Molecular Sieves with Intersecting 10- and 12-Ring Pores. Science, 262(5139), 1543-1546. doi:10.1126/science.262.5139.1543Patinec, V., Wright, P. A., Lightfoot, P., Aitken, R. A., & Cox, P. A. (1999). Synthesis of a novel microporous magnesioaluminophosphate, STA-6, containing an unbound azamacrocycle †. Journal of the Chemical Society, Dalton Transactions, (22), 3909-3911. doi:10.1039/a907259dWragg, D. S., Morris, R., Burton, A. W., Zones, S. I., Ong, K., & Lee, G. (2007). The Synthesis and Structure of SSZ-73:  an All-Silica Zeolite with an Unusual Framework Topology. Chemistry of Materials, 19(16), 3924-3932. doi:10.1021/cm0705284Cantín, A., Corma, A., Leiva, S., Rey, F., Rius, J., & Valencia, S. (2005). Synthesis and Structure of the Bidimensional Zeolite ITQ-32 with Small and Large Pores. Journal of the American Chemical Society, 127(33), 11560-11561. doi:10.1021/ja053040hBaerlocher, C., Xie, D., McCusker, L. B., Hwang, S.-J., Chan, I. Y., Ong, K., … Zones, S. I. (2008). Ordered silicon vacancies in the framework structure of the zeolite catalyst SSZ-74. Nature Materials, 7(8), 631-635. doi:10.1038/nmat2228Castañeda, R., Corma, A., Fornés, V., Rey, F., & Rius, J. (2003). Synthesis of a New Zeolite Structure ITQ-24, with Intersecting 10- and 12-Membered Ring Pores. Journal of the American Chemical Society, 125(26), 7820-7821. doi:10.1021/ja035534pCantín, A., Corma, A., Diaz-Cabanas, M. J., Jordá, J. L., & Moliner, M. (2006). Rational Design and HT Techniques Allow the Synthesis of New IWR Zeolite Polymorphs. Journal of the American Chemical Society, 128(13), 4216-4217. doi:10.1021/ja0603599Zones, S. I., Darton, R. J., Morris, R., & Hwang, S.-J. (2005). Studies on the Role of Fluoride Ion vs Reaction Concentration in Zeolite Synthesis. The Journal of Physical Chemistry B, 109(1), 652-661. doi:10.1021/jp0402434Zones, S. I., Burton, A. W., Lee, G. S., & Olmstead, M. M. (2007). A Study of Piperidinium Structure-Directing Agents in the Synthesis of Silica Molecular Sieves under Fluoride-Based Conditions. Journal of the American Chemical Society, 129(29), 9066-9079. doi:10.1021/ja0709122Burton, A. W., Lee, G. S., & Zones, S. I. (2006). Phase selectivity in the syntheses of cage-based zeolite structures: An investigation of thermodynamic interactions between zeolite hosts and structure directing agents by molecular modeling. Microporous and Mesoporous Materials, 90(1-3), 129-144. doi:10.1016/j.micromeso.2005.11.022Lopes, C. W., Gómez-Hortigüela, L., Rojas, A., & Pergher, S. B. C. (2017). Fluoride-mediated synthesis of TON and MFI zeolites using 1-butyl-3-methylimidazolium as structure-directing agent. Microporous and Mesoporous Materials, 252, 29-36. doi:10.1016/j.micromeso.2017.06.017Geisinger, K. L., Gibbs, G. V., & Navrotsky, A. (1985). A molecular orbital study of bond length and angle variations in framework structures. Physics and Chemistry of Minerals, 11(6), 266-283. doi:10.1007/bf00307405Hammonds, K. D., Heine, V., & Dove, M. T. (1998). Rigid-Unit Modes and the Quantitative Determination of the Flexibility Possessed by Zeolite Frameworks. The Journal of Physical Chemistry B, 102(10), 1759-1767. doi:10.1021/jp980006zMerlino, S. (1990). Lovdarite, K4Na12(Be8Si28O72) • 18 H2O, a zeolite-like mineral: structural features and OD character. European Journal of Mineralogy, 2(6), 809-818. doi:10.1127/ejm/2/6/0809De Man, A. J. M., Ueda, S., Annen, M. J., Davis, M. E., & van Santen, R. A. (1992). The stability and vibrational spectra of three-ring containing zeolitic silica polymorphs. Zeolites, 12(7), 789-800. doi:10.1016/0144-2449(92)90051-pBnmner, G. O., & Meier, W. M. (1989). Framework density distribution of zeolite-type tetrahedral nets. Nature, 337(6203), 146-147. doi:10.1038/337146a0Annen, M. J., Davis, M. E., Higgins, J. B., & Schlenker, J. L. (1991). VPI-7: the first zincosilicate molecular sieve containing three-membered T-atom rings. Journal of the Chemical Society, Chemical Communications, (17), 1175. doi:10.1039/c39910001175McCusker, L. B., Grosse-Kunstleve, R. W., Baerlocher, C., Yoshikawa, M., & Davis, M. E. (1996). Synthesis optimization and structure analysis of the zincosilicate molecular sieve VPI-9. Microporous Materials, 6(5-6), 295-309. doi:10.1016/0927-6513(96)00015-6Röhrig, C., & Gies, H. (1995). A New Zincosilicate Zeolite with Nine-Ring Channels. Angewandte Chemie International Edition in English, 34(1), 63-65. doi:10.1002/anie.199500631Ro¨hrig, C., Gies, H., & Marler, B. (1994). Rietveld refinement of the crystal structure of the synthetic porous zincosilicate VPI-7. Zeolites, 14(7), 498-503. doi:10.1016/0144-2449(94)90181-3Camblor, M. A., & Davis, M. E. (1994). 29Si MAS NMR Spectroscopy of Tectozincosilicates. The Journal of Physical Chemistry, 98(50), 13151-13156. doi:10.1021/j100101a010Petersen, O. V., Giester, G., Brandstatter, F., & Niedermayr, G. (2002). NABESITE, Na2BeSi4O10{middle dot}4H2O, A NEW MINERAL SPECIES FROM THE ILIMAUSSAQ ALKALINE COMPLEX, SOUTH GREENLAND. The Canadian Mineralogist, 40(1), 173-181. doi:10.2113/gscanmin.40.1.173Cheetham, A. K., Fjellvg, H., Gier, T. E., Kongshaug, K. O., Lillerud, K. P., & Stucky, G. D. (2001). 05-O-05-Very open microporous materials: from concept to reality. Zeolites and Mesoporous Materials at the dawn of the 21st century, Proceedings of the 13th International Zeolite Conference,, 158. doi:10.1016/s0167-2991(01)81268-4Walter, F. (1992). Weinebeneite, CaBe3(PO4)2(OH)2 ∙ 4H2O, a new mineral species: mineral data and crystal structure. European Journal of Mineralogy, 4(6), 1275-1284. doi:10.1127/ejm/4/6/1275Littlefield, B. T. R., & Weller, M. T. (2012). Lightweight nanoporous metal hydroxide-rich zeotypes. Nature Communications, 3(1). doi:10.1038/ncomms2129Sedlmaier, S. J., Döblinger, M., Oeckler, O., Weber, J., Schmedt auf der Günne, J., & Schnick, W. (2011). Unprecedented Zeolite-Like Framework Topology Constructed from Cages with 3-Rings in a Barium Oxonitridophosphate. Journal of the American Chemical Society, 133(31), 12069-12078. doi:10.1021/ja202159ePark, S. H., Daniels, P., & Gies, H. (2000). RUB-23: a new microporous lithosilicate containing spiro-5 building units. Microporous and Mesoporous Materials, 37(1-2), 129-143. doi:10.1016/s1387-1811(99)00260-7Conradsson, T., Dadachov, M. ., & Zou, X. . (2000). Synthesis and structure of (Me3N)6[Ge32O64](H2O)4.5, a thermally stable novel zeotype with 3D interconnected 12-ring channels. Microporous and Mesoporous Materials, 41(1-3), 183-191. doi:10.1016/s1387-1811(00)00288-2Corma, A., Diaz-Cabanas, M. J., Jiang, J., Afeworki, M., Dorset, D. L., Soled, S. L., & Strohmaier, K. G. (2010). Extra-large pore zeolite (ITQ-40) with the lowest framework density containing double four- and double three-rings. Proceedings of the National Academy of Sciences, 107(32), 13997-14002. doi:10.1073/pnas.1003009107Jiang, J., Jorda, J. L., Diaz-Cabanas, M. J., Yu, J., & Corma, A. (2010). The Synthesis of an Extra-Large-Pore Zeolite with Double Three-Ring Building Units and a Low Framework Density. Angewandte Chemie International Edition, 49(29), 4986-4988. doi:10.1002/anie.201001506Blasco, T., Corma, A., Díaz-Cabañas, M. J., Rey, F., Vidal-Moya, J. A., & Zicovich-Wilson, C. M. (2002). Preferential Location of Ge in the Double Four-Membered Ring Units of ITQ-7 Zeolite. The Journal of Physical Chemistry B, 106(10), 2634-2642. doi:10.1021/jp013302bSartbaeva, A., Wells, S. A., Treacy, M. M. J., & Thorpe, M. F. (2006). The flexibility window in zeolites. Nature Materials, 5(12), 962-965. doi:10.1038/nmat1784Medina, M. E., Platero-Prats, A. E., Snejko, N., Rojas, A., Monge, A., Gándara, F., … Camblor, M. A. (2011). Towards Inorganic Porous Materials by Design: Looking for New Architectures. Advanced Materials, 23(44), 5283-5292. doi:10.1002/adma.201101852Kapko, V., Dawson, C., Treacy, M. M. J., & Thorpe, M. F. (2010). Flexibility of ideal zeolite frameworks. Physical Chemistry Chemical Physics, 12(30), 8531. doi:10.1039/c003977bSastre, G., & Corma, A. (2010). Predicting Structural Feasibility of Silica and Germania Zeolites. The Journal of Physical Chemistry C, 114(3), 1667-1673. doi:10.1021/jp909348sRojas, A., Gómez-Hortigüela, L., & Camblor, M. A. (2013). Benzylimidazolium cations as zeolite structure-directing agents. Differences in performance brought about by a small change in size. Dalton Trans., 42(7), 2562-2571. doi:10.1039/c2dt32230gBoal, B. W., Deem, M. W., Xie, D., Kang, J. H., Davis, M. E., & Zones, S. I. (2016). Synthesis of Germanosilicate Molecular Sieves from Mono- and Di-Quaternary Ammonium OSDAs Constructed from Benzyl Imidazolium Derivatives: Stabilization of Large Micropo

Interaction of molecular and atomic hydrogen with (5,5) and (6,6) single-wall carbon nanotubes

Density functional theory has been used to study the interaction of molecular and atomic hydrogen with (5,5) and (6,6) single-wall carbon nanotubes. Static calculations allowing for different degrees of structural relaxation are performed, in addition to dynamical simulations. Molecular physisorption inside and outside the nanotube walls is predicted to be the most stable state of those systems. The binding energies for physisorption of the H2 molecule outside the nanotube are in the range 0.04–0.07 eV. This means that uptake and release of molecular hydrogen from nanotubes is a relatively easy process, as many experiments have proved. A chemisorption state, with the molecule dissociated and the two hydrogen atoms bonded to neighbor carbon atoms, has also been found. However, reaching this dissociative chemisorption state for an incoming molecule, or starting from the physisorbed molecule, is difficult because of the existence of a substantial activation barrier. The dissociative chemisorption deforms the tube and weakens the C-C bond. This effect can catalyze the shattering and scission of the tube by incoming hydrogen molecules with sufficient kinetic energy.This work was supported by DGESIC (Grant No. PB98-0345) and European Community (RTN-COMELCAN). We acknowledge the computational facilities provided by CESCA and CEPBA.Peer reviewe

Molecular clusters of hydrogen, deuterium, and tritium: especially cationic species H3+(H2)m: m=2, 5 and 14

Presentado a la Conferencia "Nanotechnology: Power of Computation for Nanotechnology" celebrada en Gran Canaria (España) el 19 de mayo de 2003.Two recent experimental studies by Zweiback et al. and by Gobet et al. have motivated us to study the ground-state geometry and the consequent electronic structure of the singly-charged cationic hydrogen cluster H3+(H2)m for m=2,5 and 14, using at first the Hartree-Fock approximation. For the H+7 cluster the fully optimized ground-state geometry yeilds an isosceles triangle H3, with charge ~ 0.85(e), and sides 0.852 and 0.884 Å flanked by two H2 molecules lying parallel to each other, wiht bond lengths of 0.740 Å. In contrast, for the H+13 cluster, the central 'building block' is equilateral H3 with bond length 0.861 Å, and with charge ~0.815(e). This configuration of H3 is flanked by three almost-parallel H2 molecules with bond length 0.739 A. MP2 refinements of geometry, charge distribution and normal mode vibrational frequencies of the cationic tritium cluster T+7 and the corresponding deuterium cluster D+13 are also reported. Finally, Hartree-Fock and MP2 results are recorded for H+13.KVA thanks the University of Antwerp for financial support under grant GOA-BOF-UA nr 23. This work received financial support from MCyT of Spain Grants MAT2001-04499 and MAT2001-0946 and the EC-RTN program NANOPHASE (contract HPRN-CT-2000-00167), Basque Country University and Basque Hezkuntza Saila.Peer reviewe

Integración de Cartotecas Virtuales como herramienta de apoyo en la investigación histórica y social

En la actualidad, la casi totalidad de las cartotecas que se encuentran en la Web son colecciones de imágenes provenientes de la digitalización de mapas originalmente en soporte papel. Ese tipo de archivos gráficos proporcionan al investigador la posibilidad de acceder a la información cartográfica histórica y visualizarla, con un grado de calidad que depende de la calidad del proceso de digitalización y de las limitaciones impuestas por el propietario de los mismos. En la mayoría de los casos, el acceso a estas cartotecas sólo sirve para una primera aproximación y no es posible utilizar esos mapas para un trabajo científico debido a las escasas herramientas disponibles para medir, comparar, analizar y/o combinar estos recursos con otro tipo de cartografía. Por ello, el establecimiento de las Cartotecas Virtuales como herramienta de apoyo a los proyectos históricos en los que se involucra a un gran número de investigadores nacionales e internacionales, supone un avance hacia la patente necesidad de los historiadores y documentalistas de poder acceder de manera remota a toda la información existente y que pueda ser ubicable a través de un único sitio que facilite su consulta

MALL, a membrane-tetra-spanning proteolipid overexpressed in cancer, is present in membraneless nuclear biomolecular condensates

Proteolipids are proteins with unusual lipid-like properties. It has long been established that PLP and plasmolipin, which are two unrelated membrane-tetra-spanning myelin proteolipids, can be converted in vitro into a water-soluble form with a distinct conformation, raising the question of whether these, or other similar proteolipids, can adopt two different conformations in the cell to adapt their structure to distinct environments. Here, we show that MALL, another proteolipid with a membrane-tetra-spanning structure, distributes in membranes outside the nucleus and, within the nucleus, in membrane-less, liquid-like PML body biomolecular condensates. Detection of MALL in one or other environment was strictly dependent on the method of cell fixation used, suggesting that MALL adopts different conformations depending on its physical environment —lipidic or aqueous— in the cell. The acquisition of the condensate-compatible conformation requires PML expression. Excess MALL perturbed the distribution of the inner nuclear membrane proteins emerin and LAP2β, and that of the DNA-binding protein BAF, leading to the formation of aberrant nuclei. This effect, which is consistent with studies identifying overexpressed MALL as an unfavorable prognostic factor in cancer, could contribute to cell malignancy. Our study establishes a link between proteolipids, membranes and biomolecular condensates, with potential biomedical implication

Mechanical behavior of asphalt mixtures containing silica gels as warm additives

This paper presents the results of a study of some compounds capable of absorbing water into their structure (silica gel), as potential foaming binders. Asphalt mixtures were manufactured at different manufacturing and compaction temperatures, using four different silica gels. Static and dynamic tests were carried out to determine their behavior in asphalt mixtures. The results were compared with those obtained using hot-mix asphalt and warm-mix asphalt manufactured with zeolite. The lab results showed a similar behavior of asphalt mixtures containing either silica gel or zeolite.The research presented herein was sponsored by the Research Office of Universidad de La Frontera (DIUFRO) under the project number DI15-0089

A data-globe and immersive virtual reality environment for upper limb rehabilitation after spinal cord injury

While a number of virtual data-gloves have been used in stroke, there is little evidence about their use in spinal cord injury (SCI). A pilot clinical experience with nine SCI subjects was performed comparing two groups: one carried out a virtual rehabilitation training based on the use of a data glove, CyberTouch combined with traditional rehabilitation, during 30 minutes a day twice a week along two weeks; while the other made only conventional rehabilitation. Furthermore, two functional indexes were developed in order to assess the patient’s performance of the sessions: normalized trajectory lengths and repeatability. While differences between groups were not statistically significant, the data-glove group seemed to obtain better results in the muscle balance and functional parameters, and in the dexterity, coordination and fine grip tests. Related to the indexes that we implemented, normalized trajectory lengths and repeatability, every patient showed an improvement in at least one of the indexes, either along Y-axis trajectory or Z-axis trajectory. This study might be a step in investigating new ways of treatments and objective measures in order to obtain more accurate data about the patient’s evolution, allowing the clinicians to develop rehabilitation treatments, adapted to the abilities and needs of the patients

A video life-world approach to consultation practice: The relevance of a socio-phenomenological approach

This article discusses the [development and] use of a video life-world schema to explore alternative orientations to the shared health consultation. It is anticipated that this schema can be used by practitioners and consumers alike to understand the dynamics of videoed health consultations, the role of the participants within it and the potential to consciously alter the outcome by altering behaviour during the process of interaction. The study examines health consultation participation and develops an interpretative method of analysis that includes image elicitation (via videos), phenomenology (to identify the components of the analytic framework), narrative (to depict the stories of interactions) and a reflexive mode (to develop shared meaning through a conceptual framework for analysis). The analytic framework is derived from a life-world conception of human mutual shared interaction which is presented here as a novel approach to understanding patient-centred care. The video materials used in this study were derived from consultations in a Walk-in Centre (WiC) in East London. The conceptual framework produced through the process of video analysis is comprised of different combinations of movement, knowledge and emotional conversations that are used to classify objective or engaged WiC health care interactions. The videoed interactions organise along an active or passive, facilitative or directive typical situation continuum illustrating different kinds of textual approaches to practice that are in tension or harmony. The schema demonstrates how practitioners and consumers interact to produce these outcomes and indicates the potential for both consumers and practitioners to be educated to develop practice dynamics that support patient-centred care and impact on health outcomes