Прямые и косвенные директивные речевые акты в речи учащихся

СТУДЕНТЫШКОЛЬНИКИРЕЧЬречевые акты директивныепрагмалингвистик

Charging a Capacitor from an External Fluctuating Potential using a Single Conical Nanopore

We explore the electrical rectification of large amplitude fluctuating signals by an asymmetric nanostructure operating in aqueous solution. We show experimentally and theoretically that a load capacitor can be charged to voltages close to 1 V within a few minutes by converting zero time-average potentials of amplitudes in the range 0.5–3 V into average net currents using a single conical nanopore. This process suggests that significant energy conversion and storage from an electrically fluctuating environment is feasible with a nanoscale pore immersed in a liquid electrolyte solution, a system characteristic of bioelectronics interfaces, electrochemical cells, and nanoporous membranes.We acknowledge the support from the Ministry of Economic Affairs and Competitiveness and FEDER (project MAT2012-32084) and the Generalitat Valenciana (project Prometeo/GV/0069).Gómez Lozano, V.; Ramirez Hoyos, P.; Cervera Montesinos, J.; Nasir, S.; Ali, M.; Ensinger, W.; Mafé, S. (2015). Charging a Capacitor from an External Fluctuating Potential using a Single Conical Nanopore. Scientific Reports. 5(9501):1-5. https://doi.org/10.1038/srep09501S1559501Astumian, R. D. Stochastic conformational pumping: A mechanism for free-energy transduction by molecules. Annu. Rev. Biophys. 40, 289–313 (2011).Qian, H. Cooperativity in cellular biochemical processes: Noise-enhanced sensitivity, fluctuating enzyme, bistability with nonlinear feedback and other mechanisms for sigmoidal responses. Annu. Rev. Biophys. 41, 179–204 (2012).Hille, B. Ionic Channels of Excitable Membranes (Sinauer Associates Inc., Sunderland, MA, 1992).Levin, M. Molecular bioelectricity in developmental biology: new tools and recent discoveries: control of cell behavior and pattern formation by transmembrane potential gradients. Bioessays 34, 205–217 (2012).Queralt-Martín, M. et al. Electrical pumping of potassium ions against an external concentration gradient in a biological ion channel. Appl. Phys. Lett. 103, 043707 (2013).Hudspeth, A. J., Choe, Y., Mehta, A. D. & Martin, P. Putting ion channels to work: Mechanoelectrical transduction, adaptation and amplification by hair cells. Proc. Nat. Acad. Sci. U.S.A. 97, 11765–11772 (2000).Siwy, Z. & Fuliński, A. Fabrication of a Synthetic Nanopore Ion Pump. Phys. Rev. Lett. 89, 198103 (2002).Siwy, Z. & Fuliński, A. A nanodevice for rectification and pumping ions. Am. J. Phys. 72, 567–574 (2004).Ramirez, P., Gomez, V., Ali, M., Ensinger, W. & Mafe, S. Net currents obtained from zero-average potentials in single amphoteric nanopores. Electrochem. Commun. 31, 137–140 (2013).Ali, M. et al. Current rectification by nanoparticle blocking in single cylindrical nanopores. Appl. Phys. Lett. 104, 043703 (2014).Misra, N. et al. Bioelectronic silicon nanowire devices using functional membrane proteins. Proc. Natl. Acad. Sci. U.S.A. 106, 13780–13784 (2009).Ramirez, P., Ali, M., Ensinger, W. & Mafe, S. Information processing with a single multifunctional nanofluidic diode. Appl. Phys. Lett. 101, 133108 (2012).Hou, Y., Vidu, R. & Stroeve, P. Solar energy storage methods. Ind. Eng. Chem. Res. 50, 8954–8964 (2011).Guo, W. et al. Energy harvesting with single-ion-selective nanopores: A concentration-gradient-driven nanofluidic power source. Adv. Funct. Mater. 20, 1339–1344 (2010).Cervera, J., Ramirez, P., Mafe, S. & Stroeve, P. Asymmetric nanopore rectification for ion pumping, electrical power generation and information processing applications. Electrochim. Acta, 56, 4504–4511 (2011).Tybrandt, K., Forchheimer, R. & Berggren, M. Logic gates based on ion transistors. Nat. Commun., 3, 871 (2012)Apel, P. Track etching technique in membrane technology. Radiat. Meas. 34, 559–566 (2001).Ali, M., Ramirez, P., Mafe, S., Neumann, R. & Ensinger, W. A pH-tunable nanofluidic diode with a broad range of rectifying properties. ACS Nano 3, 603–608 (2009).Albrecht, T. How to Understand and Interpret Current Flow in Nanopore/Electrode Devices. ACS Nano 5, 6714–6725 (2011).Ali, M. et al. Carbohydrate-Mediated Biomolecular Recognition and Gating of Synthetic Ion Channels. J. Phys. Chem. C 117, 18234–18242 (2013)

Morphological changes in electrochemically deposited poly(3,4-ethylenedioxythiophene) films during overoxidation

Electrochemical and morphological properties of thin poly(3,4-ethylenedioxy-thiophene) (PEDOT) films deposited on gold were investigated in aqueous sulfuric acid solutions. X-ray diffraction and electron microscopy were used for monitoring the morphological changes and structure evolution caused by overoxidation. The diffraction peaks of PEDOT became sharper and more intensive during the subsequent oxidation cycles. This indicates that besides the degradation of the PEDOT film, its crystallinity was gradually improved with increasing the number of oxidation cycles. These changes may result in the appearance of novel properties that may be advantageous for specific applications

Ion bipolar junction transistors

Dynamic control of chemical microenvironments is essential for continued development in numerous fields of life sciences. Such control could be achieved with active chemical circuits for delivery of ions and biomolecules. As the basis for such circuitry, we report a solid-state ion bipolar junction transistor (IBJT) based on conducting polymers and thin films of anion- and cation-selective membranes. The IBJT is the ionic analogue to the conventional semiconductor BJT and is manufactured using standard microfabrication techniques. Transistor characteristics along with a model describing the principle of operation, in which an anionic base current amplifies a cationic collector current, are presented. By employing the IBJT as a bioelectronic circuit element for delivery of the neurotransmitter acetylcholine, its efficacy in modulating neuronal cell signaling is demonstrated