Understanding the kinetic behavior of a Mo-V-Te-Nb mixed oxide in the oxydehydrogenation of ethane

Two kinetic models based on Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms were developed to describe the oxydehydrogenation of ethane to yield ethylene over a Mo-V-Te-Nb catalyst. Obtained in a lab-scale fixed-bed reactor, experimental data at the steady-state were used to estimate the kinetic models parameters via a nonisothermal regression. Experiments were performed using an ethane, oxygen and nitrogen mixture as feedstock, spanning temperatures from 673 to 753 K, inlet partial pressures of oxygen and ethane between 5.0 and 22.0 kPa, and space-time from 10 to 70 g(cat) h(molethane)- (1). Ethylene, CO and CO2 were the only detected products, the selectivity for ethylene ranged from 76% to 96% for an ethane conversion interval 4-85%. A series of tests feeding ethylene instead of ethane were also performed at 713 K, varying inlet partial pressures and space-time in the same ranges as was done for ethane. Ethylene conversion was relatively low, 3-14%, the dominant product being CO with CO/CO2 ratios from 0.73 to 0.79. The LH mechanism was found to represent better the experimental data. The oxydehydrogenation of ethane was the reaction with the lowest activation energy, 108-115 kJ mol (1). Except for the conversion of ethane into CO2, deep oxidations were detected as very energetically demanding steps, 156-193 kJ mol (1). Competitive adsorption between reagents and products occurred in the two mechanisms particularly at relatively high reaction severity, water re-adsorption being weaker in comparison with COx re-adsorption. (C) 2014 Elsevier Ltd. All rights reserved.This work was financially supported by the Instituto Mexicano del Petroleo.Quintana-Solorzano, R.; Barragan-Rodriguez, G.; Armendariz-Herrera, H.; López Nieto, JM.; Valente, JS. (2014). Understanding the kinetic behavior of a Mo-V-Te-Nb mixed oxide in the oxydehydrogenation of ethane. Fuel. 138:15-26. doi:10.1016/j.fuel.2014.07.051152613

Metal solution precursors: their role during the synthesis of MoVTeNb mixed oxide catalysts

[EN] Synthesized via the slurry method and activated at high temperature (873 K), MoVTeNb multimetallic mixed oxides are applied to catalyze the oxidative dehydrogenation of ethane to ethylene (ODHE). Mixed oxides typically contain M1 and M2 crystalline phases, the relative contribution of these phases and the respective catalytic behaviour being notably influenced by the preparation conditions of the metallic aqueous solution precursor, given the complexity of the chemical interactions of metal species in solution. Thus, detailed in situ UV-vis and Raman studies of the chemical species formed in solution during each step of the synthetic procedure are presented herein. The main role of vanadium is to form decavanadate ions, which interact with Mo species to generate an Anderson-type structure. When niobium oxalate solution is added into the MoVTe solution, a yellow-coloured gel is immediately formed due to a common ion effect. When liquid and gel phases are separated, the M1 crystalline phase is produced solely from the gel phase. Attention is also devoted to the influence and role of each metal cation (Mo, V, Te and Nb) on the formation of the active M1 crystalline phase and the catalytic behaviour in the ODHE. The catalyst constituted mostly of M1 crystalline phase is able to convert 45% of the fed ethane, with a selectivity to ethylene of around 90%.This work was financially supported by the Instituto Mexicano del Petroleo (IMP) Project D.61010. EMF thanks CONACyT Mexico and IMP. JMLN thanks DGICYT in Spain (Project CTQ2015-68951-C3-1-R).Sánchez-Valente, J.; Maya-Flores, E.; Armendariz-Herrera, H.; Quintana-Solorzano, R.; López Nieto, JM. (2018). Metal solution precursors: their role during the synthesis of MoVTeNb mixed oxide catalysts. Catalysis Science & Technology. 8(12):3123-3132. https://doi.org/10.1039/c8cy00750kS31233132812Ushikubo, T., Oshima, K., Kayou, A., Vaarkamp, M., & Hatano, M. (1997). Ammoxidation of Propane over Catalysts Comprising Mixed Oxides of Mo and V. Journal of Catalysis, 169(1), 394-396. doi:10.1006/jcat.1997.1692Ushikubo, T., Oshima, K., Kayou, A., & Hatano, M. (1997). Ammoxidation of propane over Mo-V-Nb-Te mixed oxide catalysts. Spillover and Migration of Surface Species on Catalysts, Proceedings of the 4th International Conference on Spillover, 473-480. doi:10.1016/s0167-2991(97)80871-3Ushikubo, T. (2000). Recent topics of research and development of catalysis by niobium and tantalum oxides. Catalysis Today, 57(3-4), 331-338. doi:10.1016/s0920-5861(99)00344-2Ueda, W., & Oshihara, K. (2000). Selective oxidation of light alkanes over hydrothermally synthesized Mo-V-M-O (M=Al, Ga, Bi, Sb, and Te) oxide catalysts. Applied Catalysis A: General, 200(1-2), 135-143. doi:10.1016/s0926-860x(00)00627-xWatanabe, H., & Koyasu, Y. (2000). New synthesis route for Mo–V–Nb–Te mixed oxides catalyst for propane ammoxidation. Applied Catalysis A: General, 194-195, 479-485. doi:10.1016/s0926-860x(99)00394-4Botella, P., Solsona, B., Martinez-Arias, A., & López Nieto, J. M. (2001). Catalysis Letters, 74(3/4), 149-154. doi:10.1023/a:1016614132694Oshihara, K., Hisano, T., & Ueda, W. (2001). Topics in Catalysis, 15(2/4), 153-160. doi:10.1023/a:1016630307377Botella, P., López Nieto, J. M., Solsona, B., Mifsud, A., & Márquez, F. (2002). The Preparation, Characterization, and Catalytic Behavior of MoVTeNbO Catalysts Prepared by Hydrothermal Synthesis. Journal of Catalysis, 209(2), 445-455. doi:10.1006/jcat.2002.3648Millet, J. M. M., Roussel, H., Pigamo, A., Dubois, J. L., & Jumas, J. C. (2002). Characterization of tellurium in MoVTeNbO catalysts for propane oxidation or ammoxidation. Applied Catalysis A: General, 232(1-2), 77-92. doi:10.1016/s0926-860x(02)00078-9DeSanto Jr., P., Buttrey, D. J., Grasselli, R. K., Lugmair, C. G., Volpe, A. F., Toby, B. H., & Vogt, T. (2003). Topics in Catalysis, 23(1/4), 23-38. doi:10.1023/a:1024812101856Millet, J. M. ., Baca, M., Pigamo, A., Vitry, D., Ueda, W., & Dubois, J. . (2003). Study of the valence state and coordination of antimony in MoVSbO catalysts determined by XANES and EXAFS. Applied Catalysis A: General, 244(2), 359-370. doi:10.1016/s0926-860x(02)00614-2BOTELLA, P. (2004). Selective oxidative dehydrogenation of ethane on MoVTeNbO mixed metal oxide catalysts. Journal of Catalysis, 225(2), 428-438. doi:10.1016/j.jcat.2004.04.024Holmberg, J., Grasselli, R. K., & Andersson, A. (2004). Catalytic behaviour of M1, M2, and M1/M2 physical mixtures of the Mo–V–Nb–Te–oxide system in propane and propene ammoxidation. Applied Catalysis A: General, 270(1-2), 121-134. doi:10.1016/j.apcata.2004.04.029Grasselli, R. K., Buttrey, D. J., DeSanto, P., Burrington, J. D., Lugmair, C. G., Volpe, A. F., & Weingand, T. (2004). Active centers in Mo–V–Nb–Te–O (amm)oxidation catalysts. Catalysis Today, 91-92, 251-258. doi:10.1016/j.cattod.2004.03.060Ueda, W., Vitry, D., & Katou, T. (2005). Crystalline MoVO based complex oxides as selective oxidation catalysts of propane. Catalysis Today, 99(1-2), 43-49. doi:10.1016/j.cattod.2004.09.022Murayama, H., Vitry, D., Ueda, W., Fuchs, G., Anne, M., & Dubois, J. L. (2007). Structure characterization of orthorhombic phase in MoVTeNbO catalyst by powder X-ray diffraction and XANES. Applied Catalysis A: General, 318, 137-142. doi:10.1016/j.apcata.2006.10.050Guliants, V. V., Bhandari, R., Swaminathan, B., Vasudevan, V. K., Brongersma, H. H., Knoester, A., … Han, S. (2005). Roles of Surface Te, Nb, and Sb Oxides in Propane Oxidation to Acrylic Acid over Bulk Orthorhombic Mo−V−O Phase. The Journal of Physical Chemistry B, 109(50), 24046-24055. doi:10.1021/jp054641yGrasselli, R. K., Buttrey, D. J., Burrington, J. D., Andersson, A., Holmberg, J., Ueda, W., … Volpe, A. F. (2006). Active centers, catalytic behavior, symbiosis and redox properties of MoV(Nb,Ta)TeO ammoxidation catalysts. Topics in Catalysis, 38(1-3), 7-16. doi:10.1007/s11244-006-0066-xSafonova, O. V., Deniau, B., & Millet, J.-M. M. (2006). Mechanism of the Oxidation−Reduction of the MoVSbNbO Catalyst:  In Operando X-ray Absorption Spectroscopy and Electrical Conductivity Measurements. The Journal of Physical Chemistry B, 110(47), 23962-23967. doi:10.1021/jp064347lWagner, J. B., Timpe, O., Hamid, F. A., Trunschke, A., Wild, U., Su, D. S., … Schlögl, R. (2006). Surface texturing of Mo–V–Te–Nb–O x selective oxidation catalysts. Topics in Catalysis, 38(1-3), 51-58. doi:10.1007/s11244-006-0070-1Kolen’ko, Y. V., Zhang, W., d’ Alnoncourt, R. N., Girgsdies, F., Hansen, T. W., Wolfram, T., … Trunschke, A. (2011). Synthesis of MoVTeNb Oxide Catalysts with Tunable Particle Dimensions. ChemCatChem, 3(10), 1597-1606. doi:10.1002/cctc.201100089Hävecker, M., Wrabetz, S., Kröhnert, J., Csepei, L.-I., Naumann d’Alnoncourt, R., Kolen’ko, Y. V., … Trunschke, A. (2012). Surface chemistry of phase-pure M1 MoVTeNb oxide during operation in selective oxidation of propane to acrylic acid. Journal of Catalysis, 285(1), 48-60. doi:10.1016/j.jcat.2011.09.012Ishikawa, S., Tashiro, M., Murayama, T., & Ueda, W. (2014). Seed-Assisted Synthesis of Crystalline Mo3VOx Oxides and Their Crystal Formation Mechanism. Crystal Growth & Design, 14(9), 4553-4561. doi:10.1021/cg500661pNieto, J. M. L., Botella, P., Vázquez, M. I., & Dejoz, A. (2002). The selective oxidative dehydrogenation of ethane over hydrothermally synthesised MoVTeNb catalysts. Chem. Commun., (17), 1906-1907. doi:10.1039/b204037aLópez Nieto, J. ., Botella, P., Concepción, P., Dejoz, A., & Vázquez, M. . (2004). Oxidative dehydrogenation of ethane on Te-containing MoVNbO catalysts. Catalysis Today, 91-92, 241-245. doi:10.1016/j.cattod.2004.03.040Ivars, F., Botella, P., Dejoz, A., Nieto, J. M. L., Concepción, P., & Vázquez, M. I. (2006). Selective oxidation of short-chain alkanes over hydrothermally prepared MoVTeNbO catalysts. Topics in Catalysis, 38(1-3), 59-67. doi:10.1007/s11244-006-0071-0Botella, P., Dejoz, A., Abello, M. C., Vázquez, M. I., Arrúa, L., & López Nieto, J. M. (2009). Selective oxidation of ethane: Developing an orthorhombic phase in Mo–V–X (X=Nb, Sb, Te) mixed oxides. Catalysis Today, 142(3-4), 272-277. doi:10.1016/j.cattod.2008.09.016Deniau, B., Millet, J. M. M., Loridant, S., Christin, N., & Dubois, J. L. (2008). Effect of several cationic substitutions in the M1 active phase of the MoVTeNbO catalysts used for the oxidation of propane to acrylic acid. Journal of Catalysis, 260(1), 30-36. doi:10.1016/j.jcat.2008.08.020SOLSONA, B., VAZQUEZ, M., IVARS, F., DEJOZ, A., CONCEPCION, P., & LOPEZNIETO, J. (2007). Selective oxidation of propane and ethane on diluted Mo–V–Nb–Te mixed-oxide catalysts. Journal of Catalysis, 252(2), 271-280. doi:10.1016/j.jcat.2007.09.019Nguyen, T. T., Burel, L., Nguyen, D. L., Pham-Huu, C., & Millet, J. M. M. (2012). Catalytic performance of MoVTeNbO catalyst supported on SiC foam in oxidative dehydrogenation of ethane and ammoxidation of propane. Applied Catalysis A: General, 433-434, 41-48. doi:10.1016/j.apcata.2012.04.038Nguyen, T. T., Aouine, M., & Millet, J. M. M. (2012). Optimizing the efficiency of MoVTeNbO catalysts for ethane oxidative dehydrogenation to ethylene. Catalysis Communications, 21, 22-26. doi:10.1016/j.catcom.2012.01.026Valente, J. S., Armendáriz-Herrera, H., Quintana-Solórzano, R., del Ángel, P., Nava, N., Massó, A., & López Nieto, J. M. (2014). Chemical, Structural, and Morphological Changes of a MoVTeNb Catalyst during Oxidative Dehydrogenation of Ethane. ACS Catalysis, 4(5), 1292-1301. doi:10.1021/cs500143jTHORSTEINSON, E. (1978). The oxidative dehydrogenation of ethane over catalysts containing mixed oxides of molybdenum and vanadium. Journal of Catalysis, 52(1), 116-132. doi:10.1016/0021-9517(78)90128-8Ishikawa, S., Yi, X., Murayama, T., & Ueda, W. (2014). Heptagonal channel micropore of orthorhombic Mo3VOx as catalysis field for the selective oxidation of ethane. Applied Catalysis A: General, 474, 10-17. doi:10.1016/j.apcata.2013.07.050Ishikawa, S., Yi, X., Murayama, T., & Ueda, W. (2014). Catalysis field in orthorhombic Mo3VOx oxide catalyst for the selective oxidation of ethane, propane and acrolein. Catalysis Today, 238, 35-40. doi:10.1016/j.cattod.2013.12.054Grasselli, R. K., Burrington, J. D., Buttrey, D. J., DeSanto Jr., P., Lugmair, C. G., Volpe Jr., A. F., & Weingand, T. (2003). Topics in Catalysis, 23(1/4), 5-22. doi:10.1023/a:1024859917786Grasselli, R. K., Lugmair, C. G., Volpe Jr., A. F., Andersson, A., & Burrington, J. D. (2010). Enhancement of acrylic acid yields in propane and propylene oxidation by selective P Doping of MoV(Nb)TeO-based M1 and M2 catalysts. Catalysis Today, 157(1-4), 33-38. doi:10.1016/j.cattod.2010.01.044Grasselli, R. K., Lugmair, C. G., & Volpe, A. F. (2011). Towards an Understanding of the Reaction Pathways in Propane Ammoxidation Based on the Distribution of Elements at the Active Centers of the M1 Phase of the MoV(Nb,Ta)TeO System. Topics in Catalysis, 54(10-12), 595-604. doi:10.1007/s11244-011-9681-2Grasselli, R. K. (2014). Site isolation and phase cooperation: Two important concepts in selective oxidation catalysis: A retrospective. Catalysis Today, 238, 10-27. doi:10.1016/j.cattod.2014.05.036Ramli, I., Botella, P., Ivars, F., Pei Meng, W., Zawawi, S. M. M., Ahangar, H. A., … Nieto, J. M. L. (2011). Reflux method as a novel route for the synthesis of MoVTeNbOx catalysts for selective oxidation of propane to acrylic acid. Journal of Molecular Catalysis A: Chemical, 342-343, 50-57. doi:10.1016/j.molcata.2011.04.009Naraschewski, F. N., Praveen Kumar, C., Jentys, A., & Lercher, J. A. (2011). Phase formation and selective oxidation of propane over MoVTeNbOx catalysts with varying compositions. Applied Catalysis A: General, 391(1-2), 63-69. doi:10.1016/j.apcata.2010.07.005Blasco, T., Botella, P., Concepción, P., López Nieto, J. M., Martinez-Arias, A., & Prieto, C. (2004). Selective oxidation of propane to acrylic acid on K-doped MoVSbO catalysts: catalyst characterization and catalytic performance. Journal of Catalysis, 228(2), 362-373. doi:10.1016/j.jcat.2004.08.036YANG, X., FENG, R., JI, W., & AU, C. (2008). Characterization and evaluation of MoVTeNb mixed metal oxide catalysts fabricated via hydrothermal process with ultrasonic pretreatment for propane partial oxidation. Journal of Catalysis, 253(1), 57-65. doi:10.1016/j.jcat.2007.10.020GAFFNEY, A., CHATURVEDI, S., CLARKJR, M., HAN, S., LE, D., RYKOV, S., & CHEN, J. (2005). Characterization and catalytic studies of PVD synthesized Mo/V/Nb/Te oxide catalysts. Journal of Catalysis, 229(1), 12-23. doi:10.1016/j.jcat.2004.09.013Espinal, L., Malinger, K. A., Espinal, A. E., Gaffney, A. M., & Suib, S. L. (2007). Preparation of Multicomponent Metal Oxides Using Nozzle Spray and Microwaves. Advanced Functional Materials, 17(14), 2572-2579. doi:10.1002/adfm.200600744Kolen’ko, Y. V., Amakawa, K., d’ Alnoncourt, R. N., Girgsdies, F., Weinberg, G., Schlögl, R., & Trunschke, A. (2012). Unusual Phase Evolution in MoVTeNb Oxide Catalysts Prepared by a Novel Acrylamide-Gelation Route. ChemCatChem, 4(4), 495-503. doi:10.1002/cctc.201100451Concepción, P., Hernández, S., & Nieto, J. M. L. (2011). On the nature of active sites in MoVTeO and MoVTeNbO catalysts: The influence of catalyst activation temperature. Applied Catalysis A: General, 391(1-2), 92-101. doi:10.1016/j.apcata.2010.05.011Botella, P., García-González, E., López Nieto, J. M., & González-Calbet, J. M. (2005). MoVTeNbO multifunctional catalysts: Correlation between constituent crystalline phases and catalytic performance. Solid State Sciences, 7(5), 507-519. doi:10.1016/j.solidstatesciences.2005.01.012Beato, P., Blume, A., Girgsdies, F., Jentoft, R. E., Schlögl, R., Timpe, O., … Mohd Salim, L. (2006). Analysis of structural transformations during the synthesis of a MoVTeNb mixed oxide catalyst. Applied Catalysis A: General, 307(1), 137-147. doi:10.1016/j.apcata.2006.03.014Celaya Sanfiz, A., Hansen, T. W., Girgsdies, F., Timpe, O., Rödel, E., Ressler, T., … Schlögl, R. (2008). Preparation of Phase-Pure M1 MoVTeNb Oxide Catalysts by Hydrothermal Synthesis—Influence of Reaction Parameters on Structure and Morphology. Topics in Catalysis, 50(1-4), 19-32. doi:10.1007/s11244-008-9106-zOzeki, T., Kihara, H., & Ikeda, S. (1988). Study of equilibria in 0.03 mM molybdate acidic aqueous solutions by factor analysis applied to ultraviolet spectra. Analytical Chemistry, 60(19), 2055-2059. doi:10.1021/ac00170a014Tytko, K.-H., & Schönfeld, B. (1975). Über Isopolymolybdatfeststoffe und deren Beziehung zu Isopolymolybdationen in wäßriger Lösung / Concerning Solid Isopolymolybdates and their Relation to Isopolymolybdate Ions in Aqueous Solution. Zeitschrift für Naturforschung B, 30(7-8), 471-484. doi:10.1515/znb-1975-7-801Müller, A., Krickemeyer, E., Bögge, H., Schmidtmann, M., & Peters, F. (1998). Organizational Forms of Matter: An Inorganic Super Fullerene and Keplerate Based on Molybdenum Oxide. Angewandte Chemie International Edition, 37(24), 3359-3363. doi:10.1002/(sici)1521-3773(19981231)37:243.0.co;2-jLivage, J. (2010). Hydrothermal Synthesis of Nanostructured Vanadium Oxides. Materials, 3(8), 4175-4195. doi:10.3390/ma3084175C. F. Baes Jr and R. E.Mesmer , in The Hydrolysis of Cations , Wiley N.Y. , 1970Tsuji, H., & Koyasu, Y. (2002). Synthesis of MoVNbTe(Sb)OxComposite Oxide Catalysts via Reduction of Polyoxometalates in an Aqueous Medium. Journal of the American Chemical Society, 124(20), 5608-5609. doi:10.1021/ja0122344Maksimovskaya, R. I., Bondareva, V. M., & Aleshina, G. I. (2008). NMR Spectroscopic Studies of Interactions in Solution during the Synthesis of MoVTeNb Oxide Catalysts. European Journal of Inorganic Chemistry, 2008(31), 4906-4914. doi:10.1002/ejic.200800500Griffith, W. P., & Lesniak, P. J. B. (1969). Raman studies on species in aqueous solutions. Part III. Vanadates, molybdates, and tungstates. Journal of the Chemical Society A: Inorganic, Physical, Theoretical, 1066. doi:10.1039/j19690001066Butler, I. S., El-Sherbeny, H. A. M., Kenawy, I. M., & Mostafa, S. I. (2013). Synthesis and spectroscopic characterization of complexes of Cr(III), Cr(VI), Cu(III), Zn(II), Mo(VI), Pd(II), Ag(III), Au(III) and W(VI) with telluric acid. Journal of Molecular Structure, 1036, 510-520. doi:10.1016/j.molstruc.2012.11.017Müller, A., Kögerler, P., & Dress, A. W. M. (2001). Giant metal-oxide-based spheres and their topology: from pentagonal building blocks to keplerates and unusual spin systems. Coordination Chemistry Reviews, 222(1), 193-218. doi:10.1016/s0010-8545(01)00391-5Botto, I. L., Cabello, C. I., & Thomas, H. J. (1997). (NH4)6[TeMo6O24]·7H2O Anderson phase as precursor of the TeMo5O16 catalytic phase: thermal and spectroscopic studies. Materials Chemistry and Physics, 47(1), 37-45. doi:10.1016/s0254-0584(97)80025-9Sun, Y., Liu, J., & Wang, E. (1986). Preparation and properties of some new 6-heteropoly-tellurate compounds of tungsten and molybdenum containing vanadium. Inorganica Chimica Acta, 117(1), 23-26. doi:10.1016/s0020-1693(00)88061-5Yoshida, H., Tanaka, T., Yoshida, T., Funabiki, T., & Yoshida, S. (1996). Control of the structure of niobium oxide species on silica by the equilibrium adsorption method. Catalysis Today, 28(1-2), 79-89. doi:10.1016/0920-5861(95)00232-4Kubouchi, Y., Hayakawa, S., Namatame, H., & Hirokawa, T. (2012). Direct observation of fractional change of niobium ionic species in a solution by means of X-ray absorption fine structure spectroscopy. X-Ray Spectrometry, 41(4), 259-263. doi:10.1002/xrs.2390Prasetyoko, D., Ramli, Z., Endud, S., & Nur, H. (2005). Preparation and characterization of bifunctional oxidative and acidic catalysts Nb2O5/TS-1 for synthesis of diols. Materials Chemistry and Physics, 93(2-3), 443-449. doi:10.1016/j.matchemphys.2005.03.030Konya, T., Katou, T., Murayama, T., Ishikawa, S., Sadakane, M., Buttrey, D., & Ueda, W. (2013). An orthorhombic Mo3VOxcatalyst most active for oxidative dehydrogenation of ethane among related complex metal oxides. Catal. Sci. Technol., 3(2), 380-387. doi:10.1039/c2cy20444dOliver, J. (2004). The effect of pH on structural and catalytic properties of MoVTeNbO catalysts. Applied Catalysis A: General, 257(1), 67-76. doi:10.1016/s0926-860x(03)00632-

Wireless measurement system for structural health monitoring with high time synchronization accuracy

Structural health monitoring (SHM) systems have excellent potential to improve the regular operation and maintenance of structures. Wireless networks (WNs) have been used to avoid the high cost of traditional generic wired systems. The most important limitation of SHM wireless systems is time-synchronization accuracy, scalability, and reliability. A complete wireless system for structural identification under environmental load is designed, implemented, deployed, and tested on three different real bridges. Our contribution ranges from the hardware to the graphical front end. System goal is to avoid the main limitations of WNs for SHM particularly in regard to reliability, scalability, and synchronization. We reduce spatial jitter to 125 ns, far below the 120 μs required for high-precision acquisition systems and much better than the 10-μs current solutions, without adding complexity. The system is scalable to a large number of nodes to allow for dense sensor coverage of real-world structures, only limited by a compromise between measurement length and mandatory time to obtain the final result. The system addresses a myriad of problems encountered in a real deployment under difficult conditions, rather than a simulation or laboratory test bed

Some advances in extensive bridge monitoring using low cost dynamic characterization

Dynamic measurements will become a standard for bridge monitoring in the near future. This fact will produce an important cost reduction for maintenance. US Administration has a long term intensive research program in order to diminish the estimated current maintenance cost of US$7 billion per year over 20 years. An optimal intervention maintenance program demands a historical dynamical record, as well as an updated mathematical model of the structure to be monitored. In case that a model of the structure is not actually available it is possible to produce it, however this possibility does not exist for missing measurement records from the past. Current acquisition systems to monitor structures can be made more efficient by introducing the following improvements, under development in the Spanish research Project “Low cost bridge health monitoring by ambient vibration tests using wireless sensors”: (a) a complete wireless system to acquire sensor data, (b) a wireless system that permits the localization and the hardware identification of the whole sensor system. The applied localization system has been object of a recent patent, and (c) automatization of the modal identification process, aimed to diminish human intervention. This system is assembled with cheap components and allows the simultaneous use of a large number of sensors at a low placement cost. The engineer’s intervention is limited to the selection of sensor positions, probably based on a preliminary FE analysis. In case of multiple setups, also the position of a number of fixed reference sensors has to be decided. The wireless localization system will obtain the exact coordinates of all these sensors positions. When the selection of optimal positions is difficult, for example because of the lack of a proper FE model, this can be compensated by using a higher number of measuring (also reference) points. The described low cost acquisition system allows the responsible bridge administration to obtain historical dynamic identification records at reasonable costs that will be used in future maintenance programs. Therefore, due to the importance of the baseline monitoring record of a new bridge, a monitoring test just after its construction should be highly recommended, if not compulsory

TAT-Mediated Transduction of MafA Protein In Utero Results in Enhanced Pancreatic Insulin Expression and Changes in Islet Morphology

Alongside Pdx1 and Beta2/NeuroD, the transcription factor MafA has been shown to be instrumental in the maintenance of the beta cell phenotype. Indeed, a combination of MafA, Pdx1 and Ngn3 (an upstream regulator of Beta2/NeuroD) was recently reported to lead to the effective reprogramming of acinar cells into insulin-producing beta cells. These experiments set the stage for the development of new strategies to address the impairment of glycemic control in diabetic patients. However, the clinical applicability of reprogramming in this context is deemed to be poor due to the need to use viral vehicles for the delivery of the above factors. Here we describe a recombinant transducible version of the MafA protein (TAT-MafA) that penetrates across cell membranes with an efficiency of 100% and binds to the insulin promoter in vitro. When injected in utero into living mouse embryos, TAT-MafA significantly up-regulates target genes and induces enhanced insulin production as well as cytoarchitectural changes consistent with faster islet maturation. As the latest addition to our armamentarium of transducible proteins (which already includes Pdx1 and Ngn3), the purification and characterization of a functional TAT-MafA protein opens the door to prospective therapeutic uses that circumvent the use of viral delivery. To our knowledge, this is also the first report on the use of protein transduction in utero

Amplified Genes May Be Overexpressed, Unchanged, or Downregulated in Cervical Cancer Cell Lines

Several copy number-altered regions (CNAs) have been identified in the genome of cervical cancer, notably, amplifications of 3q and 5p. However, the contribution of copy-number alterations to cervical carcinogenesis is unresolved because genome-wide there exists a lack of correlation between copy-number alterations and gene expression. In this study, we investigated whether CNAs in the cell lines CaLo, CaSki, HeLa, and SiHa were associated with changes in gene expression. On average, 19.2% of the cell-line genomes had CNAs. However, only 2.4% comprised minimal recurrent regions (MRRs) common to all the cell lines. Whereas 3q had limited common gains (13%), 5p was entirely duplicated recurrently. Genome-wide, only 15.6% of genes located in CNAs changed gene expression; in contrast, the rate in MRRs was up to 3 times this. Chr 5p was confirmed entirely amplified by FISH; however, maximum 33.5% of the explored genes in 5p were deregulated. In 3q, this rate was 13.4%. Even in 3q26, which had 5 MRRs and 38.7% recurrently gained SNPs, the rate was only 15.1%. Interestingly, up to 19% of deregulated genes in 5p and 73% in 3q26 were downregulated, suggesting additional factors were involved in gene repression. The deregulated genes in 3q and 5p occurred in clusters, suggesting local chromatin factors may also influence gene expression. In regions amplified discontinuously, downregulated genes increased steadily as the number of amplified SNPs increased (p<0.01, Spearman's correlation). Therefore, partial gene amplification may function in silencing gene expression. Additional genes in 1q, 3q and 5p could be involved in cervical carcinogenesis, specifically in apoptosis. These include PARP1 in 1q, TNFSF10 and ECT2 in 3q and CLPTM1L, AHRR, PDCD6, and DAP in 5p. Overall, gene expression and copy-number profiles reveal factors other than gene dosage, like epigenetic or chromatin domains, may influence gene expression within the entirely amplified genome segments

Distinct colonization patterns and cDNA-AFLP transcriptome profiles in compatible and incompatible interactions between melon and different races of Fusarium oxysporum f. sp. melonis

Background: Fusarium oxysporum f. sp. melonis Snyd. & Hans. (FOM) causes Fusarium wilt, the most important infectious disease of melon (Cucumis melo L.). The four known races of this pathogen can be distinguished only by infection on appropriate cultivars. No molecular tools are available that can discriminate among the races, and the molecular basis of compatibility and disease progression are poorly understood. Resistance to races 1 and 2 is controlled by a single dominant gene, whereas only partial polygenic resistance to race 1,2 has been described. We carried out a large-scale cDNA-AFLP analysis to identify host genes potentially related to resistance and susceptibility as well as fungal genes associated with the infection process. At the same time, a systematic reisolation procedure on infected stems allowed us to monitor fungal colonization in compatible and incompatible host-pathogen combinations. Results: Melon plants (cv. Charentais Fom-2), which are susceptible to race 1,2 and resistant to race 1, were artificially infected with a race 1 strain of FOM or one of two race 1,2 w strains. Host colonization of stems was assessed at 1, 2, 4, 8, 14, 16, 18 and 21 days post inoculation (dpi), and the fungus was reisolated from infected plants. Markedly different colonization patterns were observed in compatible and incompatible host-pathogen combinations. Five time points from the symptomless early stage (2 dpi) to obvious wilting symptoms (21 dpi) were considered for cDNA-AFLP analysis. After successful sequencing of 627 transcript-derived fragments (TDFs) differentially expressed in infected plants, homology searching retrieved 305 melon transcripts, 195 FOM transcripts expressed in planta and 127 orphan TDFs. RNA samples from FOM colonies of the three strains grown in vitro were also included in the analysis to facilitate the detection of in planta-specific transcripts and to identify TDFs differentially expressed among races/strains. Conclusion: Our data suggest that resistance against FOM in melon involves only limited transcriptional changes, and that wilting symptoms could derive, at least partially, from an active plant response. We discuss the pathogen-derived transcripts expressed in planta during the infection process and potentially related to virulence functions, as well as transcripts that are differentially expressed between the two FOM races grown in vitro. These transcripts provide candidate sequences that can be further tested for their ability to distinguish between races. Sequence data from this article have been deposited in GenBank, Accession Numbers: HO867279-HO867981

Employment generation by small firms in Spain

Despite the relevance in terms of policy, we still know little in Spain about where and by whom jobs are created, and how that is affecting the size distribution of firms. The main innovation of this paper is to use a rich database that overcomes the problems encountered by other firm-level studies to shed some light on the employment generation of small firms in Spain. We find that small firms contribute to employment disproportionately across all sectors of the economy although the difference between their employment and job creation share is largest in the manufacturing sector. The job creators in that sector are both new and established firms whereas only new small firms outperform their larger counterparts in the service sector. The large annual job creation of the small firm size class is shifting the firm size distribution towards the very small production units, although not uniformly across industries of different technology intensit

Worldwide trends in diabetes since 1980: a pooled analysis of 751 population-based studies with 4.4 million participants

BACKGROUND: One of the global targets for non-communicable diseases is to halt, by 2025, the rise in the age-standardised adult prevalence of diabetes at its 2010 levels. We aimed to estimate worldwide trends in diabetes, how likely it is for countries to achieve the global target, and how changes in prevalence, together with population growth and ageing, are affecting the number of adults with diabetes. METHODS: We pooled data from population-based studies that had collected data on diabetes through measurement of its biomarkers. We used a Bayesian hierarchical model to estimate trends in diabetes prevalence—defined as fasting plasma glucose of 7·0 mmol/L or higher, or history of diagnosis with diabetes, or use of insulin or oral hypoglycaemic drugs—in 200 countries and territories in 21 regions, by sex and from 1980 to 2014. We also calculated the posterior probability of meeting the global diabetes target if post-2000 trends continue. FINDINGS: We used data from 751 studies including 4 372 000 adults from 146 of the 200 countries we make estimates for. Global age-standardised diabetes prevalence increased from 4·3% (95% credible interval 2·4–7·0) in 1980 to 9·0% (7·2–11·1) in 2014 in men, and from 5·0% (2·9–7·9) to 7·9% (6·4–9·7) in women. The number of adults with diabetes in the world increased from 108 million in 1980 to 422 million in 2014 (28·5% due to the rise in prevalence, 39·7% due to population growth and ageing, and 31·8% due to interaction of these two factors). Age-standardised adult diabetes prevalence in 2014 was lowest in northwestern Europe, and highest in Polynesia and Micronesia, at nearly 25%, followed by Melanesia and the Middle East and north Africa. Between 1980 and 2014 there was little change in age-standardised diabetes prevalence in adult women in continental western Europe, although crude prevalence rose because of ageing of the population. By contrast, age-standardised adult prevalence rose by 15 percentage points in men and women in Polynesia and Micronesia. In 2014, American Samoa had the highest national prevalence of diabetes (>30% in both sexes), with age-standardised adult prevalence also higher than 25% in some other islands in Polynesia and Micronesia. If post-2000 trends continue, the probability of meeting the global target of halting the rise in the prevalence of diabetes by 2025 at the 2010 level worldwide is lower than 1% for men and is 1% for women. Only nine countries for men and 29 countries for women, mostly in western Europe, have a 50% or higher probability of meeting the global target. INTERPRETATION: Since 1980, age-standardised diabetes prevalence in adults has increased, or at best remained unchanged, in every country. Together with population growth and ageing, this rise has led to a near quadrupling of the number of adults with diabetes worldwide. The burden of diabetes, both in terms of prevalence and number of adults affected, has increased faster in low-income and middle-income countries than in high-income countries. FUNDING: Wellcome Trust

Erratum to: Methods for evaluating medical tests and biomarkers

[This corrects the article DOI: 10.1186/s41512-016-0001-y.]