31,924 research outputs found
Transient outward K+ current (ITO) reduction prolongs action potentials and promotes afterdepolarisations: a dynamic-clamp study in human and rabbit cardiac atrial myocytes
No full textBackground and aim: Human atrial transient outward K+ current (ITO) is decreased in a variety of cardiac pathologies, but how ITO reduction alters action potentials (AP) and arrhythmia mechanisms is poorly understood, owing to non-selectivity of ITO blockers.<p></p>
Aim: to investigate effects of selective ITO changes on AP shape and duration (APD), and on afterdepolarisations or abnormal automaticity with beta-adrenergic-stimulation, using the dynamic-clamp technique in atrial cells.<p></p>
Methods and Results: Human and rabbit atrial cells were isolated by enzymatic dissociation, and electrical activity recorded by whole-cell-patch clamp (35-37oC). Dynamic-clamp-simulated ITO reduction or block slowed AP phase 1 and elevated the plateau, significantly prolonging APD, in both species. In human atrial cells, ITO block (100% ITO subtraction) increased APD50 by 31%, APD90 by 17%, and APD-61mV (reflecting cellular effective refractory period) by 22% (P<0.05 for each). Interrupting ITO block at various time points during repolarisation revealed that the APD90 increase resulted mainly from plateau-elevation, rather than from phase 1-slowing or any residual ITO. In rabbit atrial cells, partial ITO block (~40% ITO subtraction) reversibly increased the incidence of cellular arrhythmic depolarisations (CADs; afterdepolarisations and/or abnormal automaticity) in the presence of the beta-agonist isoproterenol (0.1 μM; ISO), from 0% to 64% (P<0.05). ISO-induced CADs were significantly suppressed by dynamic-clamp increase in ITO (~40% ITO addition). ISO+ITO decrease-induced CADs were abolished by beta1-antagonism with atenolol at therapeutic concentration (1 μM).<p></p>
Conclusion. Atrial cell action potential changes from selective ITO modulation, shown for the first time using dynamic-clamp, have the potential to influence reentrant and non-reentrant arrhythmia mechanisms, with implications for both the development and treatment of atrial fibrillation
Bonding InGaAsP/ITO/Si Hybrid Laser With ITO as Cathode and Light-Coupling Material
No full textA 1.5-mu m InGaAsP/ITO/Si hybrid laser with indium tin oxide (ITO) as both a cathode and a light-coupling material is presented. The InGaAsP gain structure with a transparent ITO cathode is flip-chip bonded onto a patterned silicon-on-insulator wafer. The light generated in the InGaAsP multiquantum wells is coupled through the ITO cathode into the Si waveguide to form an InGaAsP/ITO/Si hybrid laser. The threshold current density of this hybrid laser is 20 kA/cm(2) at 210 K. Due to the advantages of post-bonding and simplicity of the fabrication process, such a hybrid laser may be a promising Si light source.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000302534300023&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Engineering, Electrical & ElectronicOpticsPhysics, AppliedSCI(E)EI14ARTICLE8712-7142
Método potenciodinâmico aplicado ao estudo da difusão iônica limitada por camada porosa em substratos de ITO
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Física, Florianópolis, 2013.Esta dissertação tem como objetivo estudar o comportamento do substrato transparente condutor composto por óxido de índio dopado com estanho (ITO) durante tratamento catódico em eletrólitos inertes de NaCl, KCl, KI e AlCl3, em diferentes concentrações possuindo a mesma força iônica e em seu pH natural. Após o tratamento é observada a formação de partículas esféricas metálicas de In-Sn, decorrentes da redução do ITO. A morfologia dos depósitos varia com o eletrólito usado e com a velocidade do processo de redução. Os resultados obtidos através dos estudos potenciodinâmicos dos eletrodos indicam um processo controlado por resistência ôhmica. O comportamento resistivo observado durante a formação da camada porosa metálica sugere a aplicação do modelo de resistência de camada porosa LPRM (do inglês Layer-Pore Resistance Model) para análise do processo. No entanto, o modelo LPRM, na forma como foi originalmente desenvolvido, não descreve bem o processo. Uma modificação ao modelo é proposta, a partir da qual, logra-se obter bons ajustes do modelo às curvas potenciodinâmicas. O conjunto de parâmetros extraído do ajuste de curvas obtidas com diferentes taxas de varredura mostra boa correlação com o crescimento da camada porosa e pode ser interpretado como uma medida do caminho difusivo que os íons do eletrólito necessitam percorrer para atingir a camada de ITO subjacente. A modificação da morfologia do substrato durante o processo de redução catódica foi caracterizada por microscopia eletrônica de varredura (MEV) e microscopia de força atômica (AFM). Da análise da rugosidade superficial, obtida das micrografias de AFM, extraiu-se o comprimento de correlação, que mede a granularidade da camada porosa. Usando conceitos simples de passeio aleatório, foi possível estabelecer uma relação entre o caminho difusivo iônico determinado eletroquimicamente, e a morfologia da camada porosa, para os diferentes eletrólitos utilizados.Abstract : This work investigates the behavior of transparent conducting substrates composed of indium tin oxide (ITO) during cathodic treatment in inert aqueous electrolytes (NaCl, KCl, KI e AlCl3), using different concentrations with same ionic force. The treatment causes the formation of spherical metallic particles of In-Sn, resulting from ITO reduction. It is possible to observe that the morphology of deposits is affected by the electrolyte composition and sweep rate. Potentiodynamic studies indicate a process controlled by Ohmic resistance. The resistive behavior observed during growth of the porous metallic layer suggests the application of the Layer-Pore Resistance Model (LPRM) to analyze the results. However, the LPRM model, in its original form, does not give a good description of the process. A modified version of the LPRM is proposed, which yields very good fits to the potentiodynamic curves. The set of fit parameters extracted from the curves, obtained at different scan rates, shows a good correlation with the growth of the porous layer, and could be interpreted as a measure of diffusion paths that ions must travel to reach the underlying ITO layer. The changes on morphology of the substrates during the cathodic reduction was characterized by scanning electron microscope (SEM) and atomic force microscope (AFM). From the roughness analysis obtained from the AFM micrographs, a correlation length was determined that describes the granularity of the porous layer. Using simple concepts of random walk, it was possible to establish a relationship between the ionic diffusion path determined electrochemically, and the morphology of porous layer, for the different electrolytes used
Letter from Kazuo Ito to Lea Perry, July 15, 1942
No full textTranscript of a letter from Kazuo Ito to Lea Perry. The original letters are housed with the Sonoma County Japanese American Citizens League (JACL), and were borrowed for digitization courtesy of the JACL, December 2014. Digital reproduction of the original item is found in item: ssu_nbea_0010.The North Bay Ethnic Archive features material related to the forced relocation of northern San Francisco Bay Area residents to the Granada (Amache) incarceration camp, Colorado. It includes correspondence, photographs, and reports. Some of the original items are housed with the Sonoma County Japanese American Citizens League (JACL), and were borrowed for digitization courtesy of the JACL. The remainder are housed in Special Collections
Letter from Kazuo Ito to Lea Perry, August 13 1942
No full textTranscript of a letter from Kazuo Ito to Lea Perry. The original letters are housed with the Sonoma County Japanese American Citizens League (JACL), and were borrowed for digitization courtesy of the JACL, December 2014. Digital reproduction of the original item is found in item: ssu_nbea_0012.The North Bay Ethnic Archive features material related to the forced relocation of northern San Francisco Bay Area residents to the Granada (Amache) incarceration camp, Colorado. It includes correspondence, photographs, and reports. Some of the original items are housed with the Sonoma County Japanese American Citizens League (JACL), and were borrowed for digitization courtesy of the JACL. The remainder are housed in Special Collections
Indium tin oxide overlayered waveguides for sensor applications
No full textThe use of indium tin oxide (ITO) thin films as electrodes for integrated optical electrochemical sensor devices is discussed. The effect of various thicknesses of ITO overlayers exhibiting low resistivity and high transparency on potassium ion-exchanged waveguides fabricated in glass substrates is investigated over the wavelength range 500-900 nm. ITO overlayers are formed by reactive thermal evaporation in oxygen, followed by annealing in air to a maximum temperature of 320°C. With air as superstrate, losses in the waveguides were found to increase dramatically above 30nm ITO thickness for TE polarization, and above 50nm thickness for TM. Losses were increased over the whole wavelength range for a superstrate index close to that of water. A one-dimensional multilayer waveguide model is used in the interpretation of the experimental results
ITO-Free Solution-Processed Flexible Electrochromic Devices Based on PEDOT:PSS as Transparent Conducting Electrode
No full textElectrochromic devices (ECDs) are
emerging as novel technology for various applications ranging from
commercialized smart window glasses, goggles, and autodimming rear
view mirrors to uncommon yet more sophisticated applications such
as infrared camouflage in military and thermal control in space satellites.
The development of low-power, lightweight, inexpensive, and flexible
devices is the need of the hour. In this respect, utilizing PEDOT:PSS
as transparent conducting electrode (TCE) to replace indium tin oxide
(ITO) and metal based TCEs for ECDs is a promising solution for the
aforementioned requirements. In this work we have demonstrated the
performance of PEDOT:PSS films coated on flexible substrates, treated
with PTSA-DMSO, as TCEs for ECD applications and their comparison
with that of ITO based ECDs. The PEDOT:PSS based flexible TCEs used
in this study have conductivity of 1400–1500 S·cm–1 and figure of merit (FoM) of 70–77. The process
of increasing the conductivity of PEDOT:PSS films also led to the
broadening of the conducting potential window (CPW), which is important
for electrochemical applications of PEDOT:PSS when used as a stand-alone
electrode. More than achieving a comparable electrochromic contrast,
switching time, and coloration efficiency with respect to the ITO
based ECDs, PEDOT:PSS devices also had the added advantage of good
mechanical flexibility. These devices demonstrated superior stability
during electrochemical cycling and multiple mechanical bending tests,
making them an inexpensive alternative to the costly ITO based ECD
technology
Magnetoresistance in triphenyl-diamine derivative blue organic light emitting devices
No full textCopyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Journal of Applied Physics 103, 043706 (2008) and may be found at
S-ROCK METHODS FOR STIFF ITO SDEs
No full textIn this paper, we present a class of explicit numerical methods for stiff Ito stochastic differential equations (SDEs). These methods are a simple to program and to use as the well-known Euler-Maruyama method, but much more efficient for stiff SDEs. For such problems, it is well known that standard explicit methods face step-size reduction. While semi-implicit methods can avoid these problems at the cost of solving (possibly large) nonlinear systems, we show that the step-size reduction phenomena can be reduced significantly for explicit methods by using stabilization techniques. Stabilized explicit numerical methods called S-ROCK (for stochastic orthogonal Runge-Kutta Chebyshev) have been introduced in [C. R. Acad. Sci. Paris, 345(10), 2007] as an alternative to (semi-) implicit methods for the solution of stiff stochastic systems. in this paper we discuss a genuine Ito version of the S-ROCK methods which avoid the use of transformation formulas from Stratonovich to Ito calculus. This is important for many applications. We present two families of methods for one-dimensional and multi-dimensional Wiener processes. We show that for stiff problems, significant improvement over classical explicit methods can be obtained. Convergence and stability properties of the methods are discussed and numerical examples as well as applications to the simulation of stiff chemical Langevin equations are presented.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000262867400003&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Mathematics, AppliedSCI(E)23ARTICLE4845-868
Letter from Frank Ito to Joe and Lea Perry, November 2, 1943
No full textTranscript of a letter from Frank Ito to Joe and Lea Perry. The original letters are housed with the Sonoma County Japanese American Citizens League (JACL), and were borrowed for digitization courtesy of the JACL, December 2014. Digital reproduction of the original item is found in item: ssu_nbea_0130.The North Bay Ethnic Archive features material related to the forced relocation of northern San Francisco Bay Area residents to the Granada (Amache) incarceration camp, Colorado. It includes correspondence, photographs, and reports. Some of the original items are housed with the Sonoma County Japanese American Citizens League (JACL), and were borrowed for digitization courtesy of the JACL. The remainder are housed in Special Collections
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