39 research outputs found
Wolbachia Age-Sex-Specific Density in Aedes albopictus: A Host Evolutionary Response to Cytoplasmic Incompatibility?
Wolbachia bacteria have invaded many arthropod species by inducing Cytoplasmic Incompatibility (CI). These symbionts represent fascinating objects of study for evolutionary biologists, but also powerful potential biocontrol agents. Here, we assess the density dynamics of Wolbachia infections in males and females of the mosquito Aedes albopitcus, an important vector of human pathogens, and interpret the results within an evolutionary framework.Wolbachia densities were measured in natural populations and in age controlled mosquitoes using quantitative PCR. We show that the density dynamics of the wAlbA Wolbachia strain infecting Aedes albopictus drastically differ between males and females, with a very rapid decay of infection in males only.Theory predicts that Wolbachia and its hosts should cooperate to improve the transmission of infection to offspring, because only infected eggs are protected from the effects of CI. However, incompatible matings effectively lower the fertility of infected males, so that selection acting on the host genome should tend to reduce the expression of CI in males, for example, by reducing infection density in males before sexual maturation. The rapid decay of one Wolbachia infection in Aedes albopictus males, but not in females, is consistent with this prediction. We suggest that the commonly observed reduction in CI intensity with male age reflects a similar evolutionary process. Our results also highlight the importance of monitoring infection density dynamics in both males and females to assess the efficiency of Wolbachia-based control strategies
Resistive switching and charge transport mechanisms in ITO/ZnO/p-Si devices
[EN] The resistive switching properties of ITO/ZnO/p-Si devices have been studied, which present well-defined resistance states with more than five orders of magnitude difference in current. Both the high resistance state (HRS) and the low resistance state (LRS) were induced by either sweeping or pulsing the voltage, observing some differences in the HRS. Finally, the charge transport mechanisms dominating the pristine, HRS, and LRS states have been analyzed in depth, and the obtained structural parameters suggest a partial re-oxidation of the conductive nanofilaments and a reduction of the effective conductive area.This work was financially supported by the Spanish Ministry of Economy and Competitiveness (Project Nos. TEC2012-38540-C02-01 and TEC2016-76849-C2-1-R). O.B. also acknowledges the subprogram "Ayudas para Contratos Predoctorales para la Formacion de Doctores" of the Spanish Ministry of Economy and Competitiveness for economical support. X.P., C.L., and C.G. are grateful to C. Frilay for his expertise in the maintenance of the sputtering kit used for the growth of the ZnO films.BlĂĄzquez, O.; Frieiro, J.; LĂłpez-Vidrier, J.; Guillaume, C.; Portier, X.; LabbĂ©, C.; Sanchis Kilders, P.... (2018). Resistive switching and charge transport mechanisms in ITO/ZnO/p-Si devices. Applied Physics Letters. 113(18):1-6. https://doi.org/10.1063/1.50469111611318I. G. Baek , M. S. Lee , S. Sco , M. J. Lee , D. H. Seo , D.S. Suh , J. C. Park , S. O. Park , H. S. Kim , I. K. Yoo , U.I. Chung , and J. T. Moon , in IEDM Technical Digest. IEEE International Electron Devices Meeting, 2004 ( IEEE, 2004), pp. 587â590.Waser, R., & Aono, M. (2007). Nanoionics-based resistive switching memories. Nature Materials, 6(11), 833-840. doi:10.1038/nmat2023Kaeriyama, S., Sakamoto, T., Sunamura, H., Mizuno, M., Kawaura, H., Hasegawa, T., ⊠Aono, M. (2005). A nonvolatile programmable solid-electrolyte nanometer switch. IEEE Journal of Solid-State Circuits, 40(1), 168-176. doi:10.1109/jssc.2004.837244Strukov, D. B., & Likharev, K. K. (2005). CMOL FPGA: a reconfigurable architecture for hybrid digital circuits with two-terminal nanodevices. Nanotechnology, 16(6), 888-900. doi:10.1088/0957-4484/16/6/045Mehonic, A., Cueff, S., Wojdak, M., Hudziak, S., Jambois, O., LabbĂ©, C., ⊠Kenyon, A. J. (2012). Resistive switching in silicon suboxide films. Journal of Applied Physics, 111(7), 074507. doi:10.1063/1.3701581Mehonic, A., Vrajitoarea, A., Cueff, S., Hudziak, S., Howe, H., LabbĂ©, C., ⊠Kenyon, A. J. (2013). Quantum Conductance in Silicon Oxide Resistive Memory Devices. Scientific Reports, 3(1). doi:10.1038/srep02708Pickett, M. D., Medeiros-Ribeiro, G., & Williams, R. S. (2012). A scalable neuristor built with Mott memristors. Nature Materials, 12(2), 114-117. doi:10.1038/nmat3510Jo, S. H., Chang, T., Ebong, I., Bhadviya, B. B., Mazumder, P., & Lu, W. (2010). Nanoscale Memristor Device as Synapse in Neuromorphic Systems. Nano Letters, 10(4), 1297-1301. doi:10.1021/nl904092hVescio, G., Crespo-Yepes, A., Alonso, D., Claramunt, S., Porti, M., Rodriguez, R., ⊠Aymerich, X. (2017). Inkjet Printed HfO2-Based ReRAMs: First Demonstration and Performance Characterization. IEEE Electron Device Letters, 38(4), 457-460. doi:10.1109/led.2017.2668599Valov, I. (2013). Redox-Based Resistive Switching Memories (ReRAMs): Electrochemical Systems at the Atomic Scale. ChemElectroChem, 1(1), 26-36. doi:10.1002/celc.201300165MartĂn, G., GonzĂĄlez, M. B., Campabadal, F., PeirĂł, F., Cornet, A., & EstradĂ©, S. (2017). Transmission electron microscopy assessment of conductive-filament formation in NiâHfO2âSi resistive-switching operational devices. Applied Physics Express, 11(1), 014101. doi:10.7567/apex.11.014101Simanjuntak, F. M., Panda, D., Wei, K.-H., & Tseng, T.-Y. (2016). Status and Prospects of ZnO-Based Resistive Switching Memory Devices. Nanoscale Research Letters, 11(1). doi:10.1186/s11671-016-1570-yKim, J., & Yong, K. (2011). Mechanism Study of ZnO Nanorod-Bundle Sensors for H2S Gas Sensing. The Journal of Physical Chemistry C, 115(15), 7218-7224. doi:10.1021/jp110129fYuan, Q., Zhao, Y.-P., Li, L., & Wang, T. (2009). Ab Initio Study of ZnO-Based Gas-Sensing Mechanisms: Surface Reconstruction and Charge Transfer. The Journal of Physical Chemistry C, 113(15), 6107-6113. doi:10.1021/jp810161jSeo, J. W., Park, J.-W., Lim, K. S., Yang, J.-H., & Kang, S. J. (2008). Transparent resistive random access memory and its characteristics for nonvolatile resistive switching. Applied Physics Letters, 93(22), 223505. doi:10.1063/1.3041643Rahaman, S. Z., Maikap, S., Chiu, H.-C., Lin, C.-H., Wu, T.-Y., Chen, Y.-S., ⊠Tsai, M.-J. (2010). Bipolar Resistive Switching Memory Using Cu Metallic Filament in Ge[sub 0.4]Se[sub 0.6] Solid Electrolyte. Electrochemical and Solid-State Letters, 13(5), H159. doi:10.1149/1.3339449Simanjuntak, F. M., Panda, D., Tsai, T.-L., Lin, C.-A., Wei, K.-H., & Tseng, T.-Y. (2015). Enhancing the memory window of AZO/ZnO/ITO transparent resistive switching devices by modulating the oxygen vacancy concentration of the top electrode. Journal of Materials Science, 50(21), 6961-6969. doi:10.1007/s10853-015-9247-ySimanjuntak, F. M., Prasad, O. K., Panda, D., Lin, C.-A., Tsai, T.-L., Wei, K.-H., & Tseng, T.-Y. (2016). Impacts of Co doping on ZnO transparent switching memory device characteristics. Applied Physics Letters, 108(18), 183506. doi:10.1063/1.4948598Simanjuntak, F. M., Panda, D., Tsai, T.-L., Lin, C.-A., Wei, K.-H., & Tseng, T.-Y. (2015). Enhanced switching uniformity in AZO/ZnO1âx/ITO transparent resistive memory devices by bipolar double forming. Applied Physics Letters, 107(3), 033505. doi:10.1063/1.4927284Liu, Q., Guan, W., Long, S., Jia, R., Liu, M., & Chen, J. (2008). Resistive switching memory effect of ZrO[sub 2] films with Zr[sup +] implanted. Applied Physics Letters, 92(1), 012117. doi:10.1063/1.2832660Shuai, Y., Zhou, S., BĂŒrger, D., Helm, M., & Schmidt, H. (2011). Nonvolatile bipolar resistive switching in Au/BiFeO3/Pt. Journal of Applied Physics, 109(12), 124117. doi:10.1063/1.3601113Chen, J.-Y., Hsin, C.-L., Huang, C.-W., Chiu, C.-H., Huang, Y.-T., Lin, S.-J., ⊠Chen, L.-J. (2013). Dynamic Evolution of Conducting Nanofilament in Resistive Switching Memories. Nano Letters, 13(8), 3671-3677. doi:10.1021/nl4015638Hubbard, W. A., Kerelsky, A., Jasmin, G., White, E. R., Lodico, J., Mecklenburg, M., & Regan, B. C. (2015). Nanofilament Formation and Regeneration During Cu/Al2O3 Resistive Memory Switching. Nano Letters, 15(6), 3983-3987. doi:10.1021/acs.nanolett.5b00901Liu, Q., Sun, J., Lv, H., Long, S., Yin, K., Wan, N., ⊠Liu, M. (2012). Real-Time Observation on Dynamic Growth/Dissolution of Conductive Filaments in Oxide-Electrolyte-Based ReRAM. Advanced Materials, 24(14), 1844-1849. doi:10.1002/adma.201104104Zhu, X., Wu, H.-Z., Qiu, D.-J., Yuan, Z., Jin, G., Kong, J., & Shen, W. (2010). Photoluminescence and resonant Raman scattering in N-doped ZnO thin films. Optics Communications, 283(13), 2695-2699. doi:10.1016/j.optcom.2010.03.006Cerqueira, M. F., Vasilevskiy, M. I., Oliveira, F., Rolo, A. G., Viseu, T., Ayres de Campos, J., ⊠Correia, R. (2011). Resonant Raman scattering in ZnO:Mn and ZnO:Mn:Al thin films grown by RF sputtering. Journal of Physics: Condensed Matter, 23(33), 334205. doi:10.1088/0953-8984/23/33/334205Marchewka, A., Roesgen, B., Skaja, K., Du, H., Jia, C.-L., Mayer, J., ⊠Menzel, S. (2015). Nanoionic Resistive Switching Memories: On the Physical Nature of the Dynamic Reset Process. Advanced Electronic Materials, 2(1), 1500233. doi:10.1002/aelm.201500233Krzywiecki, M., GrzÄ
dziel, L., Sarfraz, A., Iqbal, D., Szwajca, A., & Erbe, A. (2015). Zinc oxide as a defect-dominated material in thin films for photovoltaic applications â experimental determination of defect levels, quantification of composition, and construction of band diagram. Physical Chemistry Chemical Physics, 17(15), 10004-10013. doi:10.1039/c5cp00112aMurgatroyd, P. N. (1970). Theory of space-charge-limited current enhanced by Frenkel effect. Journal of Physics D: Applied Physics, 3(2), 151-156. doi:10.1088/0022-3727/3/2/308Electron emission in intense electric fields. (1928). Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character, 119(781), 173-181. doi:10.1098/rspa.1928.0091ĂzgĂŒr, Ă., Alivov, Y. I., Liu, C., Teke, A., Reshchikov, M. A., DoÄan, S., ⊠Morkoç, H. (2005). A comprehensive review of ZnO materials and devices. Journal of Applied Physics, 98(4), 041301. doi:10.1063/1.1992666Kaidashev, E. M., Lorenz, M., von Wenckstern, H., Rahm, A., Semmelhack, H.-C., Han, K.-H., ⊠Grundmann, M. (2003). High electron mobility of epitaxial ZnO thin films on c-plane sapphire grown by multistep pulsed-laser deposition. Applied Physics Letters, 82(22), 3901-3903. doi:10.1063/1.1578694Gall, D. (2016). Electron mean free path in elemental metals. Journal of Applied Physics, 119(8), 085101. doi:10.1063/1.4942216Lee, W., Park, J., Kim, S., Woo, J., Shin, J., Choi, G., ⊠Hwang, H. (2012). High Current Density and Nonlinearity Combination of Selection Device Based on TaOx/TiO2/TaOx Structure for One SelectorâOne Resistor Arrays. ACS Nano, 6(9), 8166-8172. doi:10.1021/nn3028776Kwon, D.-H., Kim, K. M., Jang, J. H., Jeon, J. M., Lee, M. H., Kim, G. H., ⊠Hwang, C. S. (2010). Atomic structure of conducting nanofilaments in TiO2 resistive switching memory. Nature Nanotechnology, 5(2), 148-153. doi:10.1038/nnano.2009.456Choi, B. J., Torrezan, A. C., Strachan, J. P., Kotula, P. G., Lohn, A. J., Marinella, M. J., ⊠Yang, J. J. (2016). HighâSpeed and LowâEnergy Nitride Memristors. Advanced Functional Materials, 26(29), 5290-5296. doi:10.1002/adfm.201600680Sun, X. (2006). Designing efficient field emission into ZnO. SPIE Newsroom. doi:10.1117/2.1200602.0101Hu, C., Wang, Q., Bai, S., Xu, M., He, D., Lyu, D., & Qi, J. (2017). The effect of oxygen vacancy on switching mechanism of ZnO resistive switching memory. Applied Physics Letters, 110(7), 073501. doi:10.1063/1.4976512Gul, F., & Efeoglu, H. (2017). Bipolar resistive switching and conduction mechanism of an Al/ZnO/Al-based memristor. Superlattices and Microstructures, 101, 172-179. doi:10.1016/j.spmi.2016.11.043BlĂĄzquez, O., MartĂn, G., Camps, I., Mariscal, A., LĂłpez-Vidrier, J., RamĂrez, J. M., ⊠Garrido, B. (2018). Memristive behaviour of Si-Al oxynitride thin films: the role of oxygen and nitrogen vacancies in the electroforming process. Nanotechnology, 29(23), 235702. doi:10.1088/1361-6528/aab744Bersuker, G., Gilmer, D. C., Veksler, D., Kirsch, P., Vandelli, L., Padovani, A., ⊠NafrĂa, M. (2011). Metal oxide resistive memory switching mechanism based on conductive filament properties. Journal of Applied Physics, 110(12), 124518. doi:10.1063/1.367156
Concurso Bienal 1975 - 1976
Contenido Casas entre mediaderos Simón Bolivar, Santiago - Conjunto Habitacional Siete Hermanas Viña del Mar - Industria Nacional del Cemento "Inacesa" Antofagasta - Central de Adquisiciones Automotrices Santiago - Estudio preinversional de vivienda y desarrollo urbano para Iquique "Cedur" - Planeamiento del equipo escolar "Centro Metropolitano" de Concepción - Sociedad de stablecimientos Educacionales - Nuede Arquitectura y Urbanismo de la Universidad de Chile - Vivienda popular en Santiago de Chile - Elemento estructural Feria Municipal de la Vega Santiago - Hotel Internacional Rocas de Santo Domingo
Acquisition of Complement Inhibitor Serine Protease Factor I and Its Cofactors C4b-Binding Protein and Factor H by Prevotella intermedia
Infection with the Gram-negative pathogen Prevotella intermedia gives rise to periodontitis and a growing number of studies implies an association of P. intermedia with rheumatoid arthritis. The serine protease Factor I (FI) is the central inhibitor of complement degrading complement components C3b and C4b in the presence of cofactors such as C4b-binding protein (C4BP) and Factor H (FH). Yet, the significance of complement inhibitor acquisition in P. intermedia infection and FI binding by Gram-negative pathogens has not been addressed. Here we show that P. intermedia isolates bound purified FI as well as FI directly from heat-inactivated human serum. FI bound to bacteria retained its serine protease activity as shown in degradation experiments with 125I-labeled C4b. Since FI requires cofactors for its activity we also investigated the binding of purified cofactors C4BP and FH and found acquisition of both proteins, which retained their activity in FI mediated degradation of C3b and C4b. We propose that FI binding by P. intermedia represents a new mechanism contributing to complement evasion by a Gram-negative bacterial pathogen associated with chronic diseases
ApivaŸ : Aquaponie innovation végétale et aquaculture: SystÚme aquaponique d'eau froide "truite" : principaux résultats et problÚmes rencontrés
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