WorldWideScience

Sample records for capacitive charge division

  1. Calculating and optimizing inter-electrode capacitances of charge division microchannel plate detectors

    Science.gov (United States)

    Xing, Yan; Chen, Bo; Zhang, Hong-Ji; Wang, Hai-Feng; He, Ling-Ping; Jin, Fang-Yuan

    2016-04-01

    Based on the principle of charge division microchannel plate detectors, the inter-electrode capacitances of charge division anodes which are related to electronic noise of the charge sensitive amplifier and crosstalk effect of the anode are presented. Under all the requirements of charge division microchannel plate detectors such as the imaging linearity and spatial resolution, decreasing the inter-electrode capacitances is one way to improve the imaging performance. In this paper, we illustrate the simulation process of calculating the inter-electrode capacitances. Moreover, a Wedge and Strip (WSZ) anode is fabricated with the picosecond laser micromachining process. Comparing the simulated capacitances and measured capacitances, the three-dimensional finite element method is proved to be valid. Furthermore, by adjusting the design parameters of the anode, the effects of the substrate permittivity, insulation width and the size of pitch on the inter-electrode capacitances have been analysed. The structure of the charge division anode has been optimized based on the simulation data.

  2. Induced Charge Capacitive Deionization

    OpenAIRE

    Rubin, S.; Suss, M. E.; Biesheuvel, P. M.; Bercovici, M.

    2016-01-01

    We demonstrate the phenomenon of induced-charge capacitive deionization (ICCDI) that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electrostatic field. The external electric field induces an electric dipole in the porous particle, leading to capacitive charging of its volume by both cations and anions at opposite poles. This regime is characterized both by a large RC charging time and a small electrochemical charge relaxation time, ...

  3. Induced Charge Capacitive Deionization

    CERN Document Server

    Rubin, S; Biesheuvel, P M; Bercovici, M

    2016-01-01

    We demonstrate the phenomenon of induced-charge capacitive deionization (ICCDI) that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electrostatic field. The external electric field induces an electric dipole in the porous particle, leading to capacitive charging of its volume by both cations and anions at opposite poles. This regime is characterized both by a large RC charging time and a small electrochemical charge relaxation time, which leads to rapid and significant deionization of ionic species from a volume which is on the scale of the particle. We show by theory and experiment that the transient response around a cylindrical particle results in spatially non-uniform charging and non-steady growth of depletion regions which emerge around the particle's poles. Potentially, ICCDI can be useful in applications where fast concentration changes of ionic species are required over large volumes.

  4. Complementary surface charge for enhanced capacitive deionization

    NARCIS (Netherlands)

    Gao, X.; Porada, S.; Omosebi, A.; Liu, K.L.; Biesheuvel, P.M.; Landon, J.

    2016-01-01

    Commercially available activated carbon cloth electrodes are treated using nitric acid and ethylenediamine solutions, resulting in chemical surface charge enhanced carbon electrodes for capacitive deionization (CDI) applications. Surface charge enhanced electrodes are then configured in a CDI cel

  5. Complementary surface charge for enhanced capacitive deionization.

    Science.gov (United States)

    Gao, X; Porada, S; Omosebi, A; Liu, K-L; Biesheuvel, P M; Landon, J

    2016-04-01

    Commercially available activated carbon cloth electrodes are treated using nitric acid and ethylenediamine solutions, resulting in chemical surface charge enhanced carbon electrodes for capacitive deionization (CDI) applications. Surface charge enhanced electrodes are then configured in a CDI cell to examine their salt removal at a fixed charging voltage and both reduced and opposite polarity discharge voltages, and subsequently compared to the salt removal of untreated electrodes. Substantially improved salt removal due to chemical surface charge and the use of a discharge voltage of opposite sign to the charging voltage is clearly demonstrated in these CDI cycling tests, an observation which for the first time validates both enhanced CDI and extended-voltage CDI effects predicted by the Donnan model [Biesheuvel et al., Colloids Interf. Sci. Comm., 10.1016/j.colcom.2015.12.001 (2016)]. Our experimental and theoretical results demonstrate that the use of carbon electrodes with optimized chemical surface charge can extend the CDI working voltage window through discharge voltages of opposite sign to the charging voltage, which can significantly enhance the salt adsorption capacity of CDI electrodes. Thus, in addition to carbon pore size distribution, chemical surface charge in carbon micropores is considered foundational for salt removal in CDI cells. PMID:26878361

  6. Large Capacitance Measurement by Multiple Uses of MBL Charge Sensor

    Science.gov (United States)

    Lee, Jung Sook; Chae, Min; Kim, Jung Bog

    2010-01-01

    A recent article by Morse described interesting electrostatics experiments using an MBL charge sensor. In this application, the charge sensor has a large capacitance compared to the charged test object, so nearly all charges can be transferred to the sensor capacitor from the capacitor to be measured. However, the typical capacitance of commercial…

  7. Nanoscale capacitance: A classical charge-dipole approximation

    OpenAIRE

    Jun-Qiang Lu; Jonathan Gonzalez; Carlos Sierra; Yang Li

    2013-01-01

    Modeling nanoscale capacitance presents particular challenge because of dynamic contribution from electrodes, which can usually be neglected in modeling macroscopic capacitance and nanoscale conductance. We present a model to calculate capacitances of nano-gap configurations and define effective capacitances of nanoscale structures. The model is implemented by using a classical atomic charge-dipole approximation and applied to calculate capacitance of a carbon nanotube nano-gap and effective ...

  8. Nonlinear dynamics of capacitive charging and desalination by porous electrodes

    OpenAIRE

    Biesheuvel, P. M.; Bazant, M.Z.

    2010-01-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by super-capacitors, water desalination and purification by capacitive deionization (or desalination), and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or spec...

  9. Nonlinear Dynamics of Capacitive Charging and Desalination by Porous Electrodes

    CERN Document Server

    Biesheuvel, P M

    2009-01-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by super-capacitors, water desalination and purification by capacitive deionization (or desalination), and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory in the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes wi...

  10. Switchless charge-discharge circuit for electrical capacitance tomography

    International Nuclear Information System (INIS)

    The main factor limiting the performance of electrical capacitance tomography (ECT) is an extremely low value of inter-electrode capacitances. The charge-discharge circuit is a well suited circuit for a small capacitance measurement due to its immunity to noise and stray capacitance, although it has a problem associated with a charge injected by the analogue switches, which results in a dc offset. This paper presents a new diode-based circuit for capacitance measurement in which a charge transfer method is realized without switches. The circuit was built and tested in one channel configuration with 16 multiplexed electrodes. The performance of the elaborated circuit and a comparison with a classic charge-discharge circuit are presented. The elaborated circuit can be used for sensors with inter-electrode capacitances not lower than 10 fF. The presented approach allows us to obtain a similar performance to the classic charge-discharge circuit, but has a simplified design. A lack of the need to synchronize the analogue switches in the transmitter and the receiver part of this circuit could be a desirable feature in the design of measurement systems integrated with electrodes. (paper)

  11. Quantum superposition of charge states on capacitively coupled superconducting islands

    NARCIS (Netherlands)

    Heij, C.P.; Dixon, D.C.; Wal, C.H. van der; Hadley, P.; Mooij, J.E.

    2003-01-01

    We investigate the ground state properties of a system containing two superconducting islands coupled capacitively by a wire. The ground state is a macroscopic superposition of charge states, even though the islands cannot exchange charge carriers. The ground state of the system is probed by measuri

  12. Quantum superposition of charge states on capacitively coupled superconducting islands

    OpenAIRE

    Heij, C. P.; Dixon, D C; van der Wal, C H; Hadley, P.; Mooij, J.E.

    2003-01-01

    We investigate the ground state properties of a system containing two superconducting islands coupled capacitively by a wire. The ground state is a macroscopic superposition of charge states, even though the islands cannot exchange charge carriers. The ground state of the system is probed by measuring the switching current of a Bloch transistor containing one of the islands. Calculations based on superpositions of charge states on both islands show good agreement with the experiments. The abi...

  13. Nonlinear dynamics of capacitive charging and desalination by porous electrodes.

    Science.gov (United States)

    Biesheuvel, P M; Bazant, M Z

    2010-03-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by supercapacitors, water desalination and purification by capacitive deionization, and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) valid in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory for the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes with different time scales: (i) in the "supercapacitor regime" of small voltages and/or early times, the porous electrode acts like a transmission line, governed by a linear diffusion equation for the electrostatic potential, scaled to the RC time of a single pore, and (ii) in the "desalination regime" of large voltages and long times, the porous electrode slowly absorbs counterions, governed by coupled, nonlinear diffusion equations for the pore-averaged potential and salt concentration. PMID:20365735

  14. MOS Capacitance-Voltage Characteristics Ⅲ.Trapping Capacitance from 2-Charge-State Impurities

    Institute of Scientific and Technical Information of China (English)

    Jie Binbin; Sah Chihtang

    2011-01-01

    Low-frequency and high-frequency capacitance-voltage curves of Metal-Oxide-Semiconductor Capacitors are presented to illustrate giant electron and hole trapping capacitances at many simultaneously present two-charge-state and one-trapped-carrier,or one-energy-level impurity species.Models described include a donor electron trap and an acceptor hole trap,both donors,both acceptors,both shallow energy levels,both deep,one shallow and one deep,and the identical donor and acceptor.Device and material parameters are selected to simulate chemically and physically realizable capacitors for fundamental trapping parameter characterizations and for electrical and optical signal processing applications.

  15. Analytical Charge Voltage Model in MOS Inversion Layer Based on Space Charge Capacitance

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The concept of Space Charge Capacitance (SCC) is proposed and used to make a novel analytical charge model of quantized inversion layer in MOS structures. Based on SCC,continuous expressions of surface potential and inversion layer carrier density are derived.Quantum mechanical effects on both inversion layer carrier density and surface potential are extensively included. The accuracy of the model is verified by the numerical solution to Schrodinger and Poisson equation and the model is demonstrated,too.

  16. An Analytical Model for Fringing Capacitance in Double gate Hetero Tunnel FET and Analysis of effect of Traps and Oxide charges on Fringing Capacitance

    Directory of Open Access Journals (Sweden)

    Brinda Bhowmick

    2012-03-01

    Full Text Available In this paper fringe capacitance of double hetero gate Tunnel FET has been studied. The physical modelfor fringe capacitance is derived considering source gate overlap and gate drain non overlap. Inerface trap charge and oxide charges are also introduced under positive bias stress and hot carrier stress and their effect on fringe capacitance is also studied. The fringe capacitance is significant speed limiter in Double gate technology. The model is tested by comparing with simulation results obtained from Sentauras TCADsimulations.

  17. An Analytical Model for Fringing Capacitance in Double gate Hetero Tunnel FET and Analysis of effect of Traps and Oxide charges on Fringing Capacitance

    OpenAIRE

    Brinda Bhowmick; Srimanta Baishya

    2012-01-01

    In this paper fringe capacitance of double hetero gate Tunnel FET has been studied. The physical model for fringe capacitance is derived considering source gate overlap and gate drain non overlap. Inerface trap charge and oxide charges are also introduced under positive bias stress and hot carrier stress and their effect on fringe capacitance is also studied. The fringe capacitance is significant speed limiter in Double gate technology. The model is tested by comparing with simulation results...

  18. Nonlinear dynamics of capacitive charging and desalination by porous electrodes

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Bazant, M.Z.

    2010-01-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by supercapacitors, water desalination and purification by capacitive deionization, and capacitive extraction of renewable energy from a salin

  19. Time-dependent ion selectivity in capacitive charging of porous electrodes

    NARCIS (Netherlands)

    Zhao, R.; Soestbergen, M.; Rijnaarts, H.H.M.; Wal, van der A.F.; Bazant, M.Z.; Biesheuvel, P.M.

    2012-01-01

    In a combined experimental and theoretical study, we show that capacitive charging of porous electrodes in multicomponent electrolytes may lead to the phenomenon of time-dependent ion selectivity of the electrical double layers (EDLs) in the electrodes. This effect is found in experiments on capacit

  20. An Analytical Model for Fringing Capacitance in Double gate Hetero Tunnel FET and Analysis of effect of Traps and Oxide charges on Fringing Capacitance

    Directory of Open Access Journals (Sweden)

    Brinda Bhowmick

    2012-02-01

    Full Text Available In this paper fringe capacitance of double hetero gate Tunnel FET has been studied. The physical model for fringe capacitance is derived considering source gate overlap and gate drain non overlap. Inerface trap charge and oxide charges are also introduced under positive bias stress and hot carrier stress and their effect on fringe capacitance is also studied. The fringe capacitance is significant speed limiter in Double gate technology. The model is tested by comparing with simulation results obtained from Sentauras TCAD simulations.

  1. Time and voltage dependence of dielectric charging in RF MEMS capacitive switches

    NARCIS (Netherlands)

    Herfst, R.W.; Steeneken, P.G.; Schmitz, J.

    2007-01-01

    A major issue in the reliability of RF MEMS capacitive switches is charge injection in the dielectric. In this study we try to establish the time and voltage dependence of dielectric charging in RF MEMS with silicon nitride as a dielectric. It is shown that the voltage shift of the CV-curve due to i

  2. Mapping Local Quantum Capacitance and Charged Impurities in Graphene via Plasmonic Impedance Imaging.

    Science.gov (United States)

    Shan, Xiaonan; Chen, Shan; Wang, Hui; Chen, Zixuan; Guan, Yan; Wang, Yixian; Wang, Shaopeng; Chen, Hong-Yuan; Tao, Nongjian

    2015-10-28

    Local quantum capacitance of graphene is imaged with plasmonics-based electrical impedance microscopy, from which the local density and polarity of charged impurities, electron and hole puddles associated with the charged impurities, and the density of the impurity states are determined. PMID:26356349

  3. Time-dependent ion selectivity in capacitive charging of porous electrodes

    OpenAIRE

    Zhao, R.; Van Soestbergen, M.; Rijnaarts, H. H. M.; Wal, van der, A.C.; Bazant, M.Z.; Biesheuvel, P. M.

    2012-01-01

    In a combined experimental and theoretical study, we show that capacitive charging of porous electrodes in multicomponent electrolytes may lead to the phenomenon of time-dependent ion selectivity of the electrical double layers (EDLs) in the electrodes. This effect is found in experiments on capacitive deionization of water containing NaCl/CaCl[subscript 2] mixtures, when the concentration of Na[superscript +] ions in the water is five times the Ca[superscript 2+]-ion concentration. In this e...

  4. The effect of surface transport on water desalination by porous electrodes undergoing capacitive charging

    OpenAIRE

    Shocron, Amit N.; Suss, Matthew E.

    2016-01-01

    Capacitive deionization (CDI) is a technology in which water is desalinated by ion electrosorption into the electric double layers (EDLs) of charging porous electrodes. In recent years significant advances have been made in modeling the charge and salt dynamics in a CDI cell, but the possible effect of surface transport within diffuse EDLs on these dynamics has not been investigated. We here present theory which includes surface transport in describing the dynamics of a charging CDI cell. Thr...

  5. Generic Microstrip R&D Topics at SCIPP: Longitudinal Charge Division and Length Limitations for Long Strips

    CERN Document Server

    Carman, Jerome K; Mistry, Khilesh; Schumm, Bruce A; Spencer, Edwin; Taylor, Aaron; Wilder, Max

    2011-01-01

    We discuss results on the use of charge division to estimate the longitudinal position of charge deposition in silicon microstrip sensors, and on the intrinsic noise limitation of microstrip sensors in the limit of long, narrow strips. We find a resolution of \\pm6% of the length of the sensor for a 10cm-long sensor. We also find that network effects significantly reduce sensor readout noise relative to naive expectations that arise from treating the detector resistance and capacitance as single discrete electronic components.

  6. Tunable capacitive coupling between two semiconductor charge qubits

    Science.gov (United States)

    Yu, Guo-Dong; Li, Hai-Ou; Cao, Gang; Xiao, Ming; Jiang, Hong-Wen; Guo, Guo-Ping

    2016-08-01

    Strong coupling between two qubits is one of the main requirements for high fidelity two-qubit logic operations. Here we experimentally investigate the capacitive coupling between two double quantum dots. A pair of open slot confinement gates is used to enhance the coupling. We find that the coupling energy J can be conveniently tuned in a broad range. Through numerical simulations, we study the effect of J on two-qubit operations. The analysis shows that our experimentally obtained J is adequate to achieve high fidelity two-qubit entanglement and logic gates.

  7. Compensation of the detector capacitance presented to charge-sensitive preamplifiers using the Miller effect

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Inyong, E-mail: iykwon@umich.edu [University of Michigan, Ann Arbor, MI (United States); Kang, Taehoon, E-mail: thnkang@umich.edu [University of Michigan, Ann Arbor, MI (United States); Wells, Byron T., E-mail: wells@galtresearch.com [Galt LLC, Ypsilanti, MI (United States); D’Aries, Lawrence J., E-mail: lawrence.j.daries.civ@mail.mil [Picatinny Arsenal, Rockaway Township, NJ (United States); Hammig, Mark D., E-mail: hammig@umich.edu [University of Michigan, Ann Arbor, MI (United States)

    2015-06-01

    This paper describes an integrated circuit design for a modified charge-sensitive amplifier (CSA) that compensates for the effect of capacitance presented by nuclear radiation detectors and other sensors. For applications that require large area semiconductor detectors or for those semiconductor sensors derived from high permittivity materials such as PbSe, the detector capacitance can degrade the system gain and bandwidth of a front-end preamplifier, resulting in extended rise times and attenuated output voltage signals during pulse formation. In order to suppress the effect of sensor capacitance, we applied a bootstrap technique into a traditional CSA. The technique exploits the Miller effect by reducing the effective voltage difference between the two sides of a radiation detector which minimizes the capacitance presented to the differential common-source amplifier. This new configuration is successfully designed to produce effective gain even at high detector capacitance. The entire circuit, including a core CSA with feedback components and a bootstrap amplifier, are implemented in a 0.18 μm CMOS process with a 3.3 V supply voltage. - Highlights: • A modified CSA was implemented for detector capacitance compensation. • Increasing detector capacitance degrades gain and rise time. • A bootstrap amplifier exploiting the Miller effect is described. • It allows using large area radiation sensors for high radiation-interaction rates. • Intensive noise analyses show that SNR is much better with the technique.

  8. On the interfacial capacitance of an electrolyte at a metallic electrode around zero surface charge

    Science.gov (United States)

    Bari Bhuiyan, Lutful; Lamperski, Stanisław

    2013-03-01

    The behaviour of the capacitance of a planar double layer containing a restricted primitive model electrolyte (equi-sized rigid ions moving in a continuum dielectric) at and around zero surface charge is examined for a polarizable electrode with particular emphasis on a metallic surface. Capacitance results are reported for symmetric valency (1:1) salts encompassing a range of concentrations and temperatures covering both electrolyte solution and ionic liquid regimes. Although the modified Poisson-Boltzmann theory is principally employed, at higher concentrations the theoretical calculations have been supplemented by Monte Carlo simulations. Capacitance anomaly, that is, increase of capacitance with temperature at low temperatures, is seen to occur when the electrode is an insulator with a low dielectric constant or when it is unpolarized. No capacitance anomaly is, however, seen for a metallic electrode with an infinite dielectric constant and in this situation the capacitance increases (a) dramatically at low temperatures (strong coupling) at a given concentration, and (b) as concentration increases at a given temperature. These capacitance trends are consistent with earlier works in the presence or absence of surface polarization and, in particular, the results for a conducting electrode at ionic liquid concentrations are consistent with that recently reported by Loth et al. [Phys. Rev. E, 82, 056102 (2010)]. Overall the theoretical predictions are qualitative to semi-quantitative with the simulations.

  9. Compensation of the detector capacitance presented to charge-sensitive preamplifiers using the Miller effect

    International Nuclear Information System (INIS)

    This paper describes an integrated circuit design for a modified charge-sensitive amplifier (CSA) that compensates for the effect of capacitance presented by nuclear radiation detectors and other sensors. For applications that require large area semiconductor detectors or for those semiconductor sensors derived from high permittivity materials such as PbSe, the detector capacitance can degrade the system gain and bandwidth of a front-end preamplifier, resulting in extended rise times and attenuated output voltage signals during pulse formation. In order to suppress the effect of sensor capacitance, we applied a bootstrap technique into a traditional CSA. The technique exploits the Miller effect by reducing the effective voltage difference between the two sides of a radiation detector which minimizes the capacitance presented to the differential common-source amplifier. This new configuration is successfully designed to produce effective gain even at high detector capacitance. The entire circuit, including a core CSA with feedback components and a bootstrap amplifier, are implemented in a 0.18 μm CMOS process with a 3.3 V supply voltage. - Highlights: • A modified CSA was implemented for detector capacitance compensation. • Increasing detector capacitance degrades gain and rise time. • A bootstrap amplifier exploiting the Miller effect is described. • It allows using large area radiation sensors for high radiation-interaction rates. • Intensive noise analyses show that SNR is much better with the technique

  10. Influence of self-affine interface roughness on the charge capacitance between two dielectric media

    NARCIS (Netherlands)

    Palasantzas, G.

    2005-01-01

    In this paper we investigate the influence of the interface roughness on the charge capacitance between two different dielectric media. Assuming the roughness fluctuations to be self-affine, it is shown that the roughness exponent H. which characterizes short wavelength roughness fluctuations, plays

  11. Gating capacitive field-effect sensors by the charge of nanoparticle/molecule hybrids.

    Science.gov (United States)

    Poghossian, Arshak; Bäcker, Matthias; Mayer, Dirk; Schöning, Michael J

    2015-01-21

    The semiconductor field-effect platform is a powerful tool for chemical and biological sensing with direct electrical readout. In this work, the field-effect capacitive electrolyte-insulator-semiconductor (EIS) structure - the simplest field-effect (bio-)chemical sensor - modified with citrate-capped gold nanoparticles (AuNPs) has been applied for a label-free electrostatic detection of charged molecules by their intrinsic molecular charge. The EIS sensor detects the charge changes in AuNP/molecule inorganic/organic hybrids induced by the molecular adsorption or binding events. The feasibility of the proposed detection scheme has been exemplarily demonstrated by realizing capacitive EIS sensors consisting of an Al-p-Si-SiO2-silane-AuNP structure for the label-free detection of positively charged cytochrome c and poly-d-lysine molecules as well as for monitoring the layer-by-layer formation of polyelectrolyte multilayers of poly(allylamine hydrochloride)/poly(sodium 4-styrene sulfonate), representing typical model examples of detecting small proteins and macromolecules and the consecutive adsorption of positively/negatively charged polyelectrolytes, respectively. For comparison, EIS sensors without AuNPs have been investigated, too. The adsorption of molecules on the surface of AuNPs has been verified via the X-ray photoelectron spectroscopy method. In addition, a theoretical model of the functioning of the capacitive field-effect EIS sensor functionalized with AuNP/charged-molecule hybrids has been discussed. PMID:25470772

  12. Improved capacitance characteristics during electrochemical charging of carbon nanotubes modified with polyoxometallate monolayers

    International Nuclear Information System (INIS)

    By modification of surfaces of multi-walled carbon nanotubes with ultra-thin monolayer-type films of phosphododecamolybdic acid, H3PMo12O40, an electrode material with improved capacitance properties is produced. It is apparent from three distinct test experiments (based on cyclic voltammetry, galavanostatic charging-discharging and AC impedance) that capacitors utilizing H3PMo12O40-modified carbon nanotubes are characterized by specific capacitances and energy densities on the levels of 40 F g-1 and 1.3 Wh kg-1, whereas the respective values for the systems built from bare carbon nanotubes are lower, 22 F g-1 and 0.7 Wh kg-1. It is reasonable to expect that fast and reversible multi-electron transfers of the Keggin-type H3PMo12O40 account for the pseudocapacitance effect and significantly contribute to the observed overall capacitance

  13. Compensation of the detector capacitance presented to charge-sensitive preamplifiers using the Miller effect

    Science.gov (United States)

    Kwon, Inyong; Kang, Taehoon; Wells, Byron T.; D'Aries, Lawrence J.; Hammig, Mark D.

    2015-06-01

    This paper describes an integrated circuit design for a modified charge-sensitive amplifier (CSA) that compensates for the effect of capacitance presented by nuclear radiation detectors and other sensors. For applications that require large area semiconductor detectors or for those semiconductor sensors derived from high permittivity materials such as PbSe, the detector capacitance can degrade the system gain and bandwidth of a front-end preamplifier, resulting in extended rise times and attenuated output voltage signals during pulse formation. In order to suppress the effect of sensor capacitance, we applied a bootstrap technique into a traditional CSA. The technique exploits the Miller effect by reducing the effective voltage difference between the two sides of a radiation detector which minimizes the capacitance presented to the differential common-source amplifier. This new configuration is successfully designed to produce effective gain even at high detector capacitance. The entire circuit, including a core CSA with feedback components and a bootstrap amplifier, are implemented in a 0.18 μm CMOS process with a 3.3 V supply voltage.

  14. Charging and discharging in ion implanted dielectric films used for capacitive radio frequency microelectromechanical systems switch

    International Nuclear Information System (INIS)

    In this work, metal-insulator-semiconductor (MIS) capacitor structure was used to investigate the dielectric charging and discharging in the capacitive radio frequency microelectromechanical switches. The insulator in MIS structure is silicon nitride films (SiN), which were deposited by either low pressure chemical vapor deposition (LPCVD) or plasma enhanced chemical vapor deposition (PECVD) processes. Phosphorus or boron ions were implanted into dielectric layer in order to introduce impurity energy levels into the band gap of SiN. The relaxation processes of the injected charges in SiN were changed due to the ion implantation, which led to the change in relaxation time of the trapped charges. In our experiments, the space charges were introduced by stressing the sample electrically with dc biasing. The effects of implantation process on charge accumulation and dissipation in the dielectric are studied by capacitance-voltage (C-V) measurement qualitatively and quantitatively. The experimental results show that the charging and discharging behavior of the ion implanted silicon nitride films deposited by LPCVD is quite different from the one deposited by PECVD. The charge accumulation in the dielectric film can be reduced by ion implantation with proper dielectric deposition method.

  15. The effect of surface transport on water desalination by porous electrodes undergoing capacitive charging

    CERN Document Server

    Shocron, Amit N

    2016-01-01

    Capacitive deionization (CDI) is a technology in which water is desalinated by ion electrosorption into the electric double layers (EDLs) of charging porous electrodes. In recent years significant advances have been made in modeling the charge and salt dynamics in a CDI cell, but the possible effect of surface transport within diffuse EDLs on these dynamics has not been investigated. We here present theory which includes surface transport in describing the dynamics of a charging CDI cell. Through our numerical solution to the presented models, the possible effect of surface transport on the CDI process is elucidated. While at some model conditions surface transport enhances the rate of CDI cell charging, counter-intuitively this additional transport pathway is found to slow down cell charging at other model conditions.

  16. Scanning capacitance microscope study of a SiO2/Si interface modified by charge injection

    Science.gov (United States)

    Tomiye, H.; Yao, T.

    We have investigated the local electrical properties of an SiO2/Si structure using a scanning capacitance microscope (SCaM) combined with an atomic force and a scanning tunneling microscope (AFM and STM). The electrical properties of the Si substrate and the SiO2/Si interface vary with position. In this experiment we have injected charge into the SiO2 and investigated the nature of charge storage at the SiO2/Si interface. We have used the combined microscope to apply a pulse to the SiO2/Si sample, causing charge to be trapped in the SiO2/Si interface. We could clearly detect the local variation of interface charge in a non-destructive manner using the SCaM and simultaneously by capacitance-voltage (C-V) characterization. The volume of the C-V curve shift along the voltage axis due to trapped charges is dependent upon the density of the trapped charges. In doing this experiment we show one of the many possible applications of the combined SCaM/AFM/STM.

  17. Effects of dielectric charging on the output voltage of a capacitive accelerometer

    Science.gov (United States)

    Qu, Hao; Yu, Huijun; Zhou, Wu; Peng, Bei; Peng, Peng; He, Xiaoping

    2016-11-01

    Output voltage drifting observed in one typical capacitive microelectromechanical system (MEMS) accelerometer is discussed in this paper. Dielectric charging effect is located as one of the major determinants of this phenomenon through a combination of experimental and theoretical studies. A theoretical model for the electromechanical effects of the dielectric surface charges within the electrode gap is established to analyze the dielectric charge effect on the output voltage. Observations of output voltage drift against time are fitted to this model in order to estimate the possible dielectric layer thickness. Meanwhile, Auger electron spectroscopy is carried out to analyze the electrode surface material composition and confirms a mixture layer of dielectric SiO2 and Si with a thickness about 5 nm, which is very close to the model estimation. In addition, observation of time-varing output drift in the variable bias voltage experiment indicates the movement of dielectric charge can be controlled by the applied electric field.

  18. Transient performance estimation of charge plasma based negative capacitance junctionless tunnel FET

    Science.gov (United States)

    Singh, Sangeeta; Kondekar, P. N.; Pal, Pawan

    2016-02-01

    We investigate the transient behavior of an n-type double gate negative capacitance junctionless tunnel field effect transistor (NC-JLTFET). The structure is realized by using the work-function engineering of metal electrodes over a heavily doped n+ silicon channel and a ferroelectric gate stack to get negative capacitance behavior. The positive feedback in the electric dipoles of ferroelectric materials results in applied gate bias boosting. Various device transient parameters viz. transconductance, output resistance, output conductance, intrinsic gain, intrinsic gate delay, transconductance generation factor and unity gain frequency are analyzed using ac analysis of the device. To study the impact of the work-function variation of control and source gate on device performance, sensitivity analysis of the device has been carried out by varying these parameters. Simulation study reveals that it preserves inherent advantages of charge-plasma junctionless structure and exhibits improved transient behavior as well.

  19. 3D capacitive vibrational micro harvester using isotropic charging of electrets deposited on vertical sidewalls

    Science.gov (United States)

    Nimo, Antwi; Mescheder, Ulrich; Müller, Bernhard; Saad Abou Elkeir, Awad

    2011-06-01

    In this paper the design and fabrication of an integrated micro energy harvester capable of harvesting electrical energy from low amplitude mechanical vibrations is presented. A specific feature of the presented energy harvester is its capability to harvest vibrational energy from different directions (3D). This is done through an innovative approach for electrets placed on vertical sidewalls and thereby allowing for miniaturization of 3D capacitive energy harvester on monolithic CMOS substrates. A new simple electret charging method using ionic hair-dryers/hair ionizers is reported and shown that it can be effectively used for electrets-based micro energy harvesters.

  20. Scanning capacitance microscopy and spectroscopy applied to local charge modifications and characterization of nitride-oxide-silicon heterostructures

    Science.gov (United States)

    Dreyer, M.; Wiesendanger, R.

    1995-10-01

    We have combined a home-built capacitance sensor with a commercial scanning force microscope to obtain a Scanning Capacitance Microscope (SCM). The SCM has been used to study Nitride-Oxide-Silicon (NOS) heterostructures which offer potential applications in charge storage technology. Charge writing and reading on a submicrometer scale is demonstrated with our SCM setup. In addition, SCM appears to be very useful for the characterization of subsurface defects in semiconductor devices which are inaccessible by most of the other scanning probe microscopies. Finally, we introduce a novel spectroscopic mode of SCM operation which offers combined voltage-dependent and spatially resolved information about inhomogeneous charge distributions in semiconductor devices.

  1. Evidence of double layer/capacitive charging in carbon nanomaterial-based solid contact polymeric ion-selective electrodes.

    Science.gov (United States)

    Cuartero, Maria; Bishop, Josiah; Walker, Raymart; Acres, Robert G; Bakker, Eric; De Marco, Roland; Crespo, Gaston A

    2016-08-11

    This paper presents the first direct spectroscopic evidence for double layer or capacitive charging of carbon nanomaterial-based solid contacts in all-solid-state polymeric ion-selective electrodes (ISEs). Here, we used synchrotron radiation-X-ray photoelectron spectroscopy (SR-XPS) and SR valence band (VB) spectroscopy in the elucidation of the charging mechanism of the SCs.

  2. Evidence of double layer/capacitive charging in carbon nanomaterial-based solid contact polymeric ion-selective electrodes.

    Science.gov (United States)

    Cuartero, Maria; Bishop, Josiah; Walker, Raymart; Acres, Robert G; Bakker, Eric; De Marco, Roland; Crespo, Gaston A

    2016-08-11

    This paper presents the first direct spectroscopic evidence for double layer or capacitive charging of carbon nanomaterial-based solid contacts in all-solid-state polymeric ion-selective electrodes (ISEs). Here, we used synchrotron radiation-X-ray photoelectron spectroscopy (SR-XPS) and SR valence band (VB) spectroscopy in the elucidation of the charging mechanism of the SCs. PMID:27405722

  3. Time-dependent ion selectivity in capacitive charging of porous electrodes.

    Science.gov (United States)

    Zhao, R; van Soestbergen, M; Rijnaarts, H H M; van der Wal, A; Bazant, M Z; Biesheuvel, P M

    2012-10-15

    In a combined experimental and theoretical study, we show that capacitive charging of porous electrodes in multicomponent electrolytes may lead to the phenomenon of time-dependent ion selectivity of the electrical double layers (EDLs) in the electrodes. This effect is found in experiments on capacitive deionization of water containing NaCl/CaCl(2) mixtures, when the concentration of Na(+) ions in the water is five times the Ca(2+)-ion concentration. In this experiment, after applying a voltage difference between two porous carbon electrodes, first the majority monovalent Na(+) cations are preferentially adsorbed in the EDLs, and later, they are gradually replaced by the minority, divalent Ca(2+) cations. In a process where this ion adsorption step is followed by washing the electrode with freshwater under open-circuit conditions, and subsequent release of the ions while the cell is short-circuited, a product stream is obtained which is significantly enriched in divalent ions. Repeating this process three times by taking the product concentrations of one run as the feed concentrations for the next, a final increase in the Ca(2+)/Na(+)-ratio of a factor of 300 is achieved. The phenomenon of time-dependent ion selectivity of EDLs cannot be explained by linear response theory. Therefore, a nonlinear time-dependent analysis of capacitive charging is performed for both porous and flat electrodes. Both models attribute time-dependent ion selectivity to the interplay between the transport resistance for the ions in the aqueous solution outside the EDL, and the voltage-dependent ion adsorption capacity of the EDLs. Exact analytical expressions are presented for the excess ion adsorption in planar EDLs (Gouy-Chapman theory) for mixtures containing both monovalent and divalent cations. PMID:22819395

  4. Enhanced charge efficiency and reduced energy use in capacitive deionization by increasing the discharge voltage.

    Science.gov (United States)

    Kim, T; Dykstra, J E; Porada, S; van der Wal, A; Yoon, J; Biesheuvel, P M

    2015-05-15

    Capacitive deionization (CDI) is an electrochemical method for water desalination using porous carbon electrodes. A key parameter in CDI is the charge efficiency, Λ, which is the ratio of salt adsorption over charge in a CDI-cycle. Values for Λ in CDI are typically around 0.5-0.8, significantly less than the theoretical maximum of unity, due to the fact that not only counterions are adsorbed into the pores of the carbon electrodes, but at the same time coions are released. To enhance Λ, ion-exchange membranes (IEMs) can be implemented. With membranes, Λ can be close to unity because the membranes only allow passage for the counterions. Enhancing the value of Λ is advantageous as this implies a lower electrical current and (at a fixed charging voltage) a reduced energy use. We demonstrate how, without the need to include IEMs, the charge efficiency can be increased to values close to the theoretical maximum of unity, by increasing the cell voltage during discharge, with only a small loss of salt adsorption capacity per cycle. In separate constant-current CDI experiments, where after some time the effluent salt concentration reaches a stable value, this value is reached earlier with increased discharge voltage. We compare the experimental results with predictions of porous electrode theory which includes an equilibrium Donnan electrical double layer model for salt adsorption in carbon micropores. Our results highlight the potential of modified operational schemes in CDI to increase charge efficiency and reduce energy use of water desalination. PMID:25278271

  5. Variation of Charge Distribution and Capacitance on Thin Wire Using the Method of Moments

    Directory of Open Access Journals (Sweden)

    Mohamed Louzazni

    2013-09-01

    Full Text Available In this paper, we attempting to determine the linear charge density and capacitance on a finite straight segment of thin charged conducting wire of length L=1 m and radius r. we assume that the charge density piecewise constant over the length and the electric potential are is one volt. If the radius are very small compared to the length r<charge density are piecewise constant onto each segment. The integral equation will be transformed to linear equation in N equation with N unknown system. We use the method of moments for solving this system and we obtained a Toeplitz matrix, the results shows the charge density for N=100 is represented on the low levels of discretisation, and the decreasing of the radius increaser the fidelity of the results.

  6. Capacitive RF MEMS switch dielectric charging and reliability: a critical review with recommendations

    International Nuclear Information System (INIS)

    This paper presents a comprehensive review of the reliability issues hampering capacitive RF MEMS switches in their development toward commercialization. Dielectric charging and its effects on device behavior are extensively addressed, as well as the application of different dielectric materials, improvements in the mechanical design and the use of advanced actuation waveforms. It is concluded that viable capacitive RF MEMS switches with a great chance of market acceptance preferably have no actuation voltage across a dielectric at all, contrary to the ‘standard’ geometry. This is substantiated by the reliability data of a number of dielectric-less MEMS switch designs. However, a dielectric can be used for the signal itself, resulting in a higher Con/Coff ratio than that one would be able to achieve in a switch without any dielectric. The other reliability issues of these devices are also covered, such as creep, RF-power-related failures and packaging reliability. This paper concludes with a recipe for a conceptual ‘ideal’ switch from a reliability point of view, based on the lessons learned. (paper)

  7. Bidirectional Flyback Converter with Multiple Series Connected Outputs for High Voltage Capacitive Charge and Discharge Applications

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe;

    2015-01-01

    by lower voltage rating MOSFETs driven by a gate drive transformer. Simulation results to compare the operation of conventional and proposed converters are provided. The advantages of proposed implementation are improved energy efficiency and lower cost. Experimental results with two series connected......This paper evaluates two different implementations of a bidirectional flyback converter for driving a capacitive electro active actuator, which must be charged and discharged from 0 V to 2.5 kV DC and vice versa, supplied from a 24 V battery. In one implementation, a high voltage MOSFET (4 k......V) in series with a high voltage blocking diode is added, in parallel with a high voltage freewheeling diode of a conventional flyback topology, to enable bidirectional operation. Experimental result from a digitally controlled bidirectional flyback converter shows that the discharge energy efficiency...

  8. Surface-treated carbon electrodes with modified potential of zero charge for capacitive deionization.

    Science.gov (United States)

    Wu, Tingting; Wang, Gang; Zhan, Fei; Dong, Qiang; Ren, Qidi; Wang, Jianren; Qiu, Jieshan

    2016-04-15

    The potential of zero charge (Epzc) of electrodes can greatly influence the salt removal capacity, charge efficiency and cyclic stability of capacitive deionization (CDI). Thus optimizing the Epzc of CDI electrodes is of great importance. A simple strategy to negatively shift the Epzc of CDI electrodes by modifying commercial activated carbon with quaternized poly (4-vinylpyridine) (AC-QPVP) is reported in this work. The Epzc of the prepared AC-QPVP composite electrode is as negative as -0.745 V vs. Ag/AgCl. Benefiting from the optimized Epzc of electrodes, the asymmetric CDI cell which consists of the AC-QPVP electrode and a nitric acid treated activated carbon (AC-HNO3) electrode exhibits excellent CDI performance. For inverted CDI, the working potential window of the asymmetric CDI cell can reach 1.4 V, and its salt removal capacity can be as high as 9.6 mg/g. For extended voltage CDI, the salt removal capacity of the asymmetric CDI cell at 1.2/-1.2 V is 20.6 mg/g, which is comparable to that of membrane CDI using pristine activated carbon as the electrodes (19.5 mg/g). The present work provides a simple method to prepare highly positively charged CDI electrodes and may pave the way for the development of high-performance CDI cells. PMID:26878480

  9. In Situ Spatially and Temporally Resolved Measurements of Salt Concentration between Charging Porous Electrodes for Desalination by Capacitive Deionization

    NARCIS (Netherlands)

    Suss, M.E.; Biesheuvel, P.M.; Baumann, T.E.; Stadermann, M.; Santiago, J.G.

    2014-01-01

    Capacitive deionization (CDI) is an emerging water desalination technique. In CDI, pairs of porous electrode capacitors are electrically charged to remove salt from brackish water present between the electrodes. We here present a novel experimental technique allowing measurement of spatially and tem

  10. Electrode Polarization in Glassy Electrolytes: Large Interfacial Capacitance Values and Indication for Pseudocapacitive Charge Storage

    OpenAIRE

    Mariappan, C. R.; Heins, T. P.; Roling, B.

    2009-01-01

    We study the electrode polarization behaviour of different Na-Ca-phosphosilicate glasses by measuring the differential capacitance between blocking Pt electrodes. At low applied dc bias voltages, we detect a linear capacitance regime with interfacial capacitance values considerably larger than expected from double layer theories and also considerably larger than found for ionic liquids with similar ion concentrations. With increasing bias voltages, the differential capacitance of interfacial ...

  11. The study of capacitive deionization behavior of a carbon nanotube electrode from the perspective of charge efficiency.

    Science.gov (United States)

    Li, Haibo; Liang, Sen; Gao, Mangmang; Li, Guolong; Li, Jin; He, Lijun

    2015-01-01

    In this work, the capacitive deionization (CDI) performance of a single-walled carbon nanotube (CNT) electrode has been studied from the point view of charge efficiency theory. It is revealed here that the charge efficiency of a CNT electrode is strongly dependent upon the cell voltage and solution concentration. Either the high cell voltage or the low ionic strength results in a high charge efficiency, implying that CDI is expected to be a promising technique for an aqueous solution with low ionic strength. Additionally, it is found that the high decay constant and high electrical double-layer capacity are beneficial to enhance electrosorption performance. PMID:25607673

  12. Continuous operation of membrane capacitive deionization cells assembled with dissimilar potential of zero charge electrode pairs.

    Science.gov (United States)

    Omosebi, Ayokunle; Gao, Xin; Rentschler, Jeffery; Landon, James; Liu, Kunlei

    2015-05-15

    The performance of single stack membrane assisted capacitive deionization cells configured with pristine and nitric acid oxidized Zorflex (ZX) electrode pairs was evaluated. The potentials of zero charge for the pristine and oxidized electrodes were respectively -0.2V and 0.2V vs. SCE. Four cell combinations of the electrodes including a pristine anode-pristine cathode, oxidized anode-pristine cathode, pristine anode-oxidized cathode, and oxidized anode-oxidized cathode were investigated. When the PZC was located within the polarization window of the electrode, diminished performance was observed. The cells were operated at 1.2 V and based on potential distribution results, the effective working potentials were ∼0.9, 0.8, 1.2, and 1.1 V for the pristine anode-pristine cathode, oxidized anode-pristine cathode, pristine anode-oxidized cathode, and oxidized anode-oxidized cathode cells, respectively. The highest electrosorption capacity of 17 mg NaCl/g ZX was observed for the pristine anode-oxidized cathode cell, where both PZCs were outside of the polarization window. PMID:25432447

  13. Two-dimensional fluid modelling of charged particle transport in radio-frequency capacitively coupled discharges

    International Nuclear Information System (INIS)

    This paper reviews the formulation and updates some numerical procedures usually adopted in two-dimensional, time-dependent fluid models to study the transport of charged particles in radio-frequency capacitively coupled discharges. The description of charged particle transport is made by solving the continuity and momentum transfer equations for electrons and ions, coupled with Poisson's equation and the electron mean energy transport equations. Inertia terms are considered in the ion momentum transfer equations, by generalizing the earlier definition of effective electric field. The electron mean energy equations are written using specific energy transport parameters, deduced from integration over the electron energy distribution function (EEDF). The model adopts the local mean energy approximation, i.e. it computes the electron transport parameters as a function of the electron mean energy, using either a homogeneous, two-term Boltzmann equation solver or a Maxwellian EEDF. More appropriate boundary conditions for the electron and ion fluxes are used successfully. The model is solved for a GEC Cell reactor type (with 6.4 cm radius and 3.2 cm interelectrode distance) operating at frequency 13.56 MHz, pressures between 10 mTorr and 10 Torr and applied voltages from 100 to 500 V, in electropositive (helium) and electronegative (silane-hydrogen) gases or gas mixtures. The ion kinetics in silane and hydrogen is updated with respect to previous works, by further considering SiH2+, H+ and H3+ ions. In general, simulation results for some typical electrical parameters are closer to experimental measurements available than calculations reported in previous works

  14. In situ spatially and temporally resolved measurements of salt concentration between charging porous electrodes for desalination by capacitive deionization.

    Science.gov (United States)

    Suss, Matthew E; Biesheuvel, P M; Baumann, Theodore F; Stadermann, Michael; Santiago, Juan G

    2014-01-01

    Capacitive deionization (CDI) is an emerging water desalination technique. In CDI, pairs of porous electrode capacitors are electrically charged to remove salt from brackish water present between the electrodes. We here present a novel experimental technique allowing measurement of spatially and temporally resolved salt concentration between the CDI electrodes. Our technique measures the local fluorescence intensity of a neutrally charged fluorescent probe which is collisionally quenched by chloride ions. To our knowledge, our system is the first to measure in situ and spatially resolved chloride concentration in a laboratory CDI cell. We here demonstrate good agreement between our dynamic measurements of salt concentration in a charging, millimeter-scale CDI system to the results of a modified Donnan porous electrode transport model. Further, we utilize our dynamic measurements to demonstrate that salt removal between our charging CDI electrodes occurs on a longer time scale than the capacitive charging time scales of our CDI cell. Compared to typical measurements of CDI system performance (namely, measurements of outflow ionic conductivity), our technique can enable more advanced and better-controlled studies of ion transport in CDI systems, which can potentially catalyze future performance improvements. PMID:24433022

  15. DNA Immobilization and Hybridization Detection by the Intrinsic Molecular Charge Using Capacitive Field-Effect Sensors Modified with a Charged Weak Polyelectrolyte Layer.

    Science.gov (United States)

    Bronder, Thomas S; Poghossian, Arshak; Scheja, Sabrina; Wu, Chunsheng; Keusgen, Michael; Mewes, Dieter; Schöning, Michael J

    2015-09-16

    Miniaturized setup, compatibility with advanced micro- and nanotechnologies, and ability to detect biomolecules by their intrinsic molecular charge favor the semiconductor field-effect platform as one of the most attractive approaches for the development of label-free DNA chips. In this work, a capacitive field-effect EIS (electrolyte-insulator-semiconductor) sensor covered with a layer-by-layer prepared, positively charged weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was used for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization. The negatively charged probe single-stranded DNA (ssDNA) molecules were electrostatically adsorbed onto the positively charged PAH layer, resulting in a preferentially flat orientation of the ssDNA molecules within the Debye length, thus yielding a reduced charge-screening effect and a higher sensor signal. Each sensor-surface modification step (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), reducing an unspecific adsorption by a blocking agent, incubation with noncomplementary DNA (ncDNA) solution) was monitored by means of capacitance-voltage and constant-capacitance measurements. In addition, the surface morphology of the PAH layer was studied by atomic force microscopy and contact-angle measurements. High hybridization signals of 34 and 43 mV were recorded in low-ionic strength solutions of 10 and 1 mM, respectively. In contrast, a small signal of 4 mV was recorded in the case of unspecific adsorption of fully mismatched ncDNA. The density of probe ssDNA and dsDNA molecules as well as the hybridization efficiency was estimated using the experimentally measured DNA immobilization and hybridization signals and a simplified double-layer capacitor model. The results of field-effect experiments were supported by fluorescence measurements, verifying the DNA-immobilization and hybridization event. PMID:26327272

  16. Effect of pH waves on capacitive charging in microfluidic flow channels

    NARCIS (Netherlands)

    Roelofs, Susan H.; Soestbergen, van Michiel; Odijk, Mathieu; Eijkel, Jan C.T.; Berg, van den Albert

    2014-01-01

    Novel energy-efficient desalination techniques, such as capacitive deionization (CDI), are a key element for the future of the fresh water supply, which is increasingly under stress due to the ever-growing world population and ongoing climate changes. CDI is a desalination technique where salt ions

  17. Current, charge, and capacitance during scanning probe oxidation of silicon. II. Electrostatic and meniscus forces acting on cantilever bending

    Science.gov (United States)

    Dagata, J. A.; Perez-Murano, F.; Martin, C.; Kuramochi, H.; Yokoyama, H.

    2004-08-01

    A comprehensive analysis of the electrical current passing through the tip-substrate junction during oxidation of silicon by scanning probe microscopy (SPM) is presented. This analysis identifies the electronic and ionic contributions to the total current, especially at the initial stages of the reaction, determines the effective contact area of the tip-substrate junction, and unifies the roles of space charge and meniscus formation. In this work, we concentrate on noncontact SPM oxidation. We analyze simultaneous force-distance and current-distance curves to demonstrate that total current flow during noncontact oxidation is significantly less for noncontact mode than for contact oxidation, although the resulting oxide volume is nearly identical. Ionization of water layers and mobile charge reorganization prior to and following meniscus formation is also shown to alter the tip-substrate capacitance and, therefore, the bending of the SPM cantilever.

  18. Charge recombination mechanism to explain the negative capacitance in dye-sensitized solar cells

    Science.gov (United States)

    Lie-Feng, Feng; Kun, Zhao; Hai-Tao, Dai; Shu-Guo, Wang; Xiao-Wei, Sun

    2016-03-01

    Negative capacitance (NC) in dye-sensitized solar cells (DSCs) has been confirmed experimentally. In this work, the recombination behavior of carriers in DSC with semiconductor interface as a carrier’s transport layer is explored theoretically in detail. Analytical results indicate that the recombination behavior of carriers could contribute to the NC of DSCs under small signal perturbation. Using this recombination capacitance we propose a novel equivalent circuit to completely explain the negative terminal capacitance. Further analysis based on the recombination complex impedance show that the NC is inversely proportional to frequency. In addition, analytical recombination resistance is composed by the alternating current (AC) recombination resistance (Rrac) and the direct current (DC) recombination resistance (Rrdc), which are caused by small-signal perturbation and the DC bias voltage, respectively. Both of two parts will decrease with increasing bias voltage. Project supported by the National Natural Science Foundation of China (Grant Nos. 11204209 and 60876035) and the Natural Science Foundation of Tianjin City, China (Grant No. 13JCZDJC32800).

  19. Capacitive Control of Spontaneously Induced Electrical Charge of Droplet by Electric Field-Assisted Pipetting

    Institute of Scientific and Technical Information of China (English)

    Horim Lee; Dongwhi Choi; Dong Sung Kim; Geunbae Lim

    2015-01-01

    The spontaneously generated electrical charge of a droplet dispensed from conventional pipetting is undesirable and unpredictable for most experiments that use pipetting. Hence, a method for controlling and removing the electrical charge needs to be developed. In this study, by using the electrode-deposited pipet tip (E-pipet tip), the charge-controlling system is newly developed and the electrical charge of a droplet is precisely controlled. The effect of electrolyte concentration and volume of the transferred solution to the electrical charge of a dispensed droplet is theoretically and experimentally investigated by using the equivalent capacitor model. Furthermore, a proof-of-concept example of the self-alignment and self-assembly of sequentially dispensed multiple droplets is demonstrated as one of the potential applications. Given that the electrical charge of the various aqueous droplets can be precisely and simply controlled, the fabricated E-pipet tip can be broadly utilized not only as a general charge-controlling platform of aqueous droplets but also as a powerful tool to explore fundamental scientific research regarding electrical charge of a droplet, such as the surface oscillation and evaporation of charged droplets.

  20. The influence of electron energy quantization in a space-charge region on the accumulation capacitance of InAs metal-oxide-semiconductor capacitors

    International Nuclear Information System (INIS)

    The influence of electron energy quantization in a space-charge region on the accumulation capacitance of the InAs-based metal-oxide-semiconductor capacitors (MOSCAPs) has been investigated by modeling and comparison with the experimental data from Au/anodic layer(4-20 nm)/n-InAs(111)A MOSCAPs. The accumulation capacitance for MOSCAPs has been calculated by the solution of Poisson equation with different assumptions and the self-consistent solution of Schrödinger and Poisson equations with quantization taken into account. It was shown that the quantization during the MOSCAPs accumulation capacitance calculations should be taken into consideration for the correct interface states density determination by Terman method and the evaluation of gate dielectric thickness from capacitance-voltage measurements

  1. A linear gate and transmitter for improving localization using the charge division method

    CERN Document Server

    Busso, L; Marcello, S; Morra, O; Panzarasa, A

    2002-01-01

    We developed an electronic system which, used with drift chambers, allows to perform a precise charge division measurement of the longitudinal coordinate, even if the sense wire is held at high voltage and a decoupling capacitor is needed. The idea is to create a temporal gate at the arrival of the signal and transmit to the ADC only this part of the signal. The gate remains open for a short period (120 ns), corresponding to the duration of the anode pulse and delivers, at its output, a pulse of amplitude linearly dependent from the input value. In this way the systematic error is better than 1% of the wire length. It introduces a considerable improvement in comparison with previously used software corrections, mainly from the linearity and simplicity point of view.

  2. Capacitive DNA Detection Driven by Electronic Charge Fluctuations in a Graphene Nanopore

    Science.gov (United States)

    Feliciano, Gustavo T.; Sanz-Navarro, Carlos; Coutinho-Neto, Mauricio Domingues; Ordejón, Pablo; Scheicher, Ralph H.; Rocha, Alexandre Reily

    2015-03-01

    The advent of parallelized automated methods for rapid whole-genome analysis has led to an exponential drop in costs, thus greatly accelerating biomedical research and discovery. Third-generation sequencing techniques, which would utilize the characteristic electrical conductance of the four different nucleotides, could facilitate longer base read lengths and an even lower price per genome. In this work, we propose and apply a quantum-classical hybrid methodology to quantitatively determine the influence of the solvent on the dynamics of DNA and the resulting electron transport properties of a prototypic sequencing device utilizing a graphene nanopore through which the nucleic-acid chain is threaded. Our results show that charge fluctuations in the nucleotides are responsible for characteristic conductance modulations in this system, which can be regarded as a field-effect transistor tuned by the dynamic aqueous environment.

  3. The chloride-channel blocker 9-anthracenecarboxylic acid reduces the nonlinear capacitance of prestin-associated charge movement.

    Science.gov (United States)

    Harasztosi, Csaba; Gummer, Anthony W

    2016-04-01

    The basis of the extraordinary sensitivity and frequency selectivity of the cochlea is a chloride-sensitive protein called prestin which can produce an electromechanical response and which resides in the basolateral plasma membrane of outer hair cells (OHCs). The compound 9-anthracenecarboxylic acid (9-AC), an inhibitor of chloride channels, has been found to reduce the electromechanical response of the cochlea and the OHC mechanical impedance. To elucidate these 9-AC effects, the functional electromechanical status of prestin was assayed by measuring the nonlinear capacitance of OHCs from the guinea-pig cochlea and of prestin-transfected human embryonic kidney 293 (HEK 293) cells. Extracellular application of 9-AC caused reversible, dose-dependent and chloride-sensitive reduction in OHC nonlinear charge transfer, Qmax . Prestin-transfected cells also showed reversible reduction in Qmax . For OHCs, intracellular 9-AC application as well as reduced intracellular pH had no detectable effect on the reduction in Qmax by extracellularly applied 9-AC. In the prestin-transfected cells, cytosolic application of 9-AC approximately halved the blocking efficacy of extracellularly applied 9-AC. OHC inside-out patches presented the whole-cell blocking characteristics. Disruption of the cytoskeleton by preventing actin polymerization with latrunculin A or by decoupling of spectrin from actin with diamide did not affect the 9-AC-evoked reduction in Qmax . We conclude that 9-AC acts on the electromechanical transducer principally by interaction with prestin rather than acting via the cytoskeleton, chloride channels or pH. The 9-AC block presents characteristics in common with salicylate, but is almost an order of magnitude faster. 9-AC provides a new tool for elucidating the molecular dynamics of prestin function. PMID:26869218

  4. A simple method of extracting the polarization charge density in the AlGaN/GaN heterostructure from current-voltage and capacitance-voltage characteristics

    Institute of Scientific and Technical Information of China (English)

    Lü Yuan-Jie; Lin Zhao-Jun; Yu Ying-Xia; Meng Ling-Guo; Cao Zhi-Fang; Luan Chong-Biao; Wang Zhan-Guo

    2012-01-01

    An Ni Schottky contact on the AlGaN/GaN heterostructure is fabricated.The flat-band voltage for the Schottky contact on the AlGaN/GaN heterostructure is obtained from the forward current-voltage characteristics.With the measured capacitance-voltage curve and the flat-band voltage,the polarization charge density in the AlGaN/GaN heterostructure is investigated,and a simple formula for calculating the polarization charge density is obtained and analyzed.With the approach described in this paper,the obtained polarization charge density agrees well with the one calculated by self-consistently solving Schrodinger's and Poisson's equations.

  5. Effect of additional charging and current density on the performance of Capacitive energy extraction based on Donnan Potential

    NARCIS (Netherlands)

    Liu, F.; Schaetzle, O.; Sales, B.B.; Saakes, M.; Buisman, C.J.N.; Hamelers, H.V.M.

    2012-01-01

    The difference in the salt concentrations of river and seawater implies that wherever they mix, energy could be extracted from the salinity gradient. This is a renewable and clean means of generating energy that makes use of a natural process. Capacitive energy extraction based on the Donnan potenti

  6. Novel Approach to Evaluation of Charging on Semiconductor Surface by Noncontact, Electrode-Free Capacitance/Voltage Measurement

    Science.gov (United States)

    Hirae, Sadao; Kohno, Motohiro; Okada, Hiroshi; Matsubara, Hideaki; Nakatani, Ikuyoshi; Kusuda, Tatsufumi; Sakai, Takamasa

    1994-04-01

    This paper describes a novel approach to the quantitative characterization of semiconductor surface charging caused by plasma exposures and ion implantations. The problems in conventional evaluation of charging are also discussed. Following the discussions above, the necessity of unified criteria is suggested for efficient development of systems or processes without charging damage. Hence, the charging saturation voltage between a top oxide surface and substrate, V s, and the charging density per unit area per second, ρ0, should be taken as criteria of charging behavior, which effectively represent the charging characteristics of both processes. The unified criteria can be obtained from the exposure time dependence of a net charging density on the thick field oxide. In order to determine V s and ρ0, the analysis using the C-V curve measured in a noncontact method with the metal-air-insulator-semiconductor (MAIS) technique is employed. The total space-charge density in oxide and its centroid can be determined at the same time by analyzing the flat-band voltage (V fb) of the MAIS capacitor as a function of the air gap. The net charge density can be obtained by analyzing the difference between the total space-charge density in oxide before and after charging. Finally, it is shown that charge damage of the large area metal-oxide-semiconductor (MOS) capacitor can be estimated from both V s and ρ0 which are obtained from results for a thick field oxide implanted with As+ and exposed to oxygen plasma.

  7. Molecular Aspects of Capacitation

    OpenAIRE

    Gulfidan Zulfikaroglu; Hulya Ozgur; Sait Polaturkey

    2010-01-01

    Male and female gamets are derived from the primordial germ cells, which migrate from the wall of the yolk sac toward the developing gonads. Following a series of mitotic divisions these cells increase in number at the gonads. The primordial germ cells differentiate into spermatogonia and take the form of mature spermatozoa after spermotogensis and spermotogenesis at puberty. Capacitation is the reaction, which includes all of the molecular and physiological events of mature sperm to gain the...

  8. Water desalination via capacitive deionization

    NARCIS (Netherlands)

    Suss, M.E.; Porada, S.; Sun, X.; Biesheuvel, P.M.; Yoon, J.; Presser, V.

    2015-01-01

    Capacitive deionization (CDI) is an emerging technology for the facile removal of charged ionic species from aqueous solutions, and is currently being widely explored for water desalination applications. The technology is based on ion electrosorption at the surface of a pair of electrically charg

  9. Efficiency of Capacitively Loaded Converters

    DEFF Research Database (Denmark)

    Andersen, Thomas; Huang, Lina; Andersen, Michael A. E.;

    2012-01-01

    is introduced as a definition of efficiency. The calculated and measured efficiency curves for charging DEAP actuator, polypropylene film capacitor and X7R MLCC are provided and compared. The attention has to be paid for the voltage dependent capacitive load, like X7R MLCC, when evaluating the charging......This paper explores the characteristic of capacitance versus voltage for dielectric electro active polymer (DEAP) actuator, 2kV polypropylene film capacitor as well as 3kV X7R multi layer ceramic capacitor (MLCC) at the beginning. An energy efficiency for capacitively loaded converters...... efficiency of converter. Based on the capacitancevoltage curve, the correct capacitance should be chosen when calculating the stored energy; otherwise misleading optimistic efficiency can always be obtained. Actually, when DEAP actuator is not available at the early developing stage, the voltage independent...

  10. Improved base-collector depletion charge and capacitance model for SiGe HBT on thin-film SOI%薄膜SOI上SiGe HBT集电结耗尽电荷和电容改进模型

    Institute of Scientific and Technical Information of China (English)

    徐小波; 张鹤鸣; 胡辉勇

    2011-01-01

    文章研究了SOI衬底上SiGe npn异质结晶体管集电结耗尽电荷和电容.根据器件实际工作情况,基于课题组前面的工作,对耗尽电荷和电容模型进行扩展和优化.研究结果表明,耗尽电荷模型具有更好的光滑性;耗尽电容模型为纵向耗尽与横向耗尽电容的串联,考虑了不同电流流动面积,与常规器件相比,SOI器件全耗尽工作模式下表现出更小的集电结耗尽电容,因此更大的正向Early电压;在纵向工作模式到横向工作模式转变的电压偏置点,耗尽电荷和电容的变化趋势发生改变.SOI薄膜上纵向SiGe HBT集电结耗尽电荷和电容模型的建立和扩展为毫米波SOI BiCMOS工艺中双极器件核心参数如Early电压、特征频率等的设计提供了有价值的参考.%The SiGe heterojunction bipolar transistor (HBT) on thin film SOI is successfully integrated with SOI CMOS by "folded collector".This paper deals with the collector depletion charge and the capacitance of this structure.An optimized model is presented based on our previous research.The results show that the charge model is smoother,and that the capacitance model with considering different current flow areas,is vertical and horizontal depletion capacitances in series,showing that the depletion capacitance is smaller than that of a bulk HBT.The charge and capacitance vary with the increase of reverse collector-base bias.This collector depletion charge and capacitance model provides valuable reference to the SOI SiGe HBT electrical parameters design and simulation such as Early voltage and transit frequency in the latest 0.13μm SOI BiCMOS technology.

  11. Tiny Change Capacitance Measuring Circuit Based on the Principl of Charging and Discharging%基于充放电原理的小电容测量电路

    Institute of Scientific and Technical Information of China (English)

    李新娥; 马铁华; 祖静; 徐鹏

    2012-01-01

    针对目前的小电容测量电路采样频率低,不能满足瞬态变化的膛压信号测量要求,提出一种基于充放电原理的小电容检测电路.该电路以基于恒流源充放电原理的信号调理电路取代了以小电容检测芯片PS021为主的信号调理电路.测试表明:该小电容检测电路的采样频率达到100 kHz,优于国内外现有水平,是一种高采样频率、高精度、低功耗、传感器壳体电容接公共地的小电容测量电路.%The present little capacitance measurement circuit sampling frequency is low,which can not meet the transient changing measurement requirements of bore pressure signal. A small capacitance detection circuit based on charge and discharge principle was proposed in this paper. The signal conditioning circuit with PS021 chips for small capacitance detection was replaced by signal conditioning circuit based on the principle of constant current source charging and discharging. Testing results showed that the sampling frequency of the little capacitance measuring circuit was up to 100 KHz, which was better than the current level inside and outside countries. It was a new capacitance measurement circuit with high sampling rate, low power consumption, and public end grounding.

  12. Voltage Dependence of Supercapacitor Capacitance

    Directory of Open Access Journals (Sweden)

    Szewczyk Arkadiusz

    2016-09-01

    Full Text Available Electronic Double-Layer Capacitors (EDLC, called Supercapacitors (SC, are electronic devices that are capable to store a relatively high amount of energy in a small volume comparing to other types of capacitors. They are composed of an activated carbon layer and electrolyte solution. The charge is stored on electrodes, forming the Helmholtz layer, and in electrolyte. The capacitance of supercapacitor is voltage- dependent. We propose an experimental method, based on monitoring of charging and discharging a supercapacitor, which enables to evaluate the charge in an SC structure as well as the Capacitance-Voltage (C-V dependence. The measurement setup, method and experimental results of charging/discharging commercially available supercapacitors in various voltage and current conditions are presented. The total charge stored in an SC structure is proportional to the square of voltage at SC electrodes while the charge on electrodes increases linearly with the voltage on SC electrodes. The Helmholtz capacitance increases linearly with the voltage bias while a sublinear increase of total capacitance was found. The voltage on SC increases after the discharge of electrodes due to diffusion of charges from the electrolyte to the electrodes. We have found that the recovery voltage value is linearly proportional to the initial bias voltage value.

  13. Reliability Capacitated Fixed-charge Location Problem%有容量限制的可靠性固定费用选址问题

    Institute of Scientific and Technical Information of China (English)

    周愉峰; 马祖军; 王恪铭

    2015-01-01

    设施网络可能面临各种失灵风险,而设施选址属于战略决策问题,短期内难以改变,因而在选址设计时需要充分考虑设施的非完全可靠性。本文针对无容量限制的可靠性固定费用选址问题进行扩展,进一步考虑设施的容量约束,基于非线性混合整数规划方法建立了一个有容量限制的可靠性固定费用选址问题优化模型。针对该模型的特点,应用线性化技术进行模型转化,并设计了一种拉格朗日松弛算法予以求解。通过多组算例分析,验证了算法的性能。算例分析结果表明设施失灵风险和设施容量对于选址决策有显著影响,因而在实际的选址决策过程中有必要充分考虑设施的失灵风险及容量约束。%Infrastructure networks have the risk of disruptions.Because facility location is a strategic decision that can not be changed in a short time, it is critical to account for the non-complete reliability of facility in designing the network.The classical reliability uncapacitated fixed-charge location problem is extended by considering the capacity constraint.And the reliability capacitated fixed-charge location problem under the risk of disruptions is formulated as a mixed integer nonlinear programming model.Considering the characteristics of the model, a lin-earization technique is applied to convert the model and a lagrangian relaxation algorithm is developed to solve the problem.A numerical example is given to verify the model and algorithm performance.The results show that facility capacity has a notable impact on location decision, and the unexpected failures of facility and capacity constraint of facility should be fully considered in real-life location decision process.

  14. Performance relations in Capacitive Deionization systems

    OpenAIRE

    Limpt, van, C.

    2010-01-01

    Capacitive Deionization (CDI) is a relatively new deionization technology based on the temporary storage of ions on an electrically charged surface. By directing a flow between two oppositely charged surfaces, negatively charged ions will adsorb onto the positively charged surface, and positively charged ions will adsorb onto the negatively charged surface. To optimize CDI design for various applications, performance relations in CDI systems have to be understood. CDI performance is determine...

  15. Characterization of space charge layer deep defects in n+-CdS/p-CdTe solar cells by temperature dependent capacitance spectroscopy

    Science.gov (United States)

    Kharangarh, P. R.; Misra, D.; Georgiou, G. E.; Chin, K. K.

    2013-04-01

    Temperature Dependent Capacitance Spectroscopy (TDCS) was used to identify carrier trapping defects in thin film n+-CdS/p-CdTe solar cells, made with evaporated Cu as a primary back contact. By investigating the reverse bias junction capacitance, TDCS allows to identify the energy levels of depletion layer defects. The trap energy levels and trap concentrations were derived from temperature-dependent capacitance spectra. Three distinct deep level traps were observed from the high-temperature (T > 300 K) TDCS due to the ionization of impurity centers located in the depletion region of n+-CdS/p-CdTe junction. The observed levels were also reported by other characterization techniques. TDCS seems to be a much simpler characterization technique for accurate evaluation of deep defects in n+-CdS/p-CdTe solar cells.

  16. Impact of GaN cap on charges in Al₂O₃/(GaN/)AlGaN/GaN metal-oxide-semiconductor heterostructures analyzed by means of capacitance measurements and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Ťapajna, M., E-mail: milan.tapajna@savba.sk; Jurkovič, M.; Válik, L.; Haščík, Š.; Gregušová, D.; Kuzmík, J. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Brunner, F.; Cho, E.-M. [Ferdinand-Braun-Institut, Leibniz Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489 Berlin (Germany); Hashizume, T. [Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, 060-0814 Sapporo, Japan and JST-CREST, 102-0075 Tokyo (Japan)

    2014-09-14

    Oxide/semiconductor interface trap density (D{sub it}) and net charge of Al₂O₃/(GaN)/AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistor (MOS-HEMT) structures with and without GaN cap were comparatively analyzed using comprehensive capacitance measurements and simulations. D{sub it} distribution was determined in full band gap of the barrier using combination of three complementary capacitance techniques. A remarkably higher D{sub it} (∼5–8 × 10¹²eV⁻¹ cm⁻²) was found at trap energies ranging from EC-0.5 to 1 eV for structure with GaN cap compared to that (D{sub it} ∼ 2–3 × 10¹²eV⁻¹ cm⁻²) where the GaN cap was selectively etched away. D{sub it} distributions were then used for simulation of capacitance-voltage characteristics. A good agreement between experimental and simulated capacitance-voltage characteristics affected by interface traps suggests (i) that very high D{sub it} (>10¹³eV⁻¹ cm⁻²) close to the barrier conduction band edge hampers accumulation of free electron in the barrier layer and (ii) the higher D{sub it} centered about EC-0.6 eV can solely account for the increased C-V hysteresis observed for MOS-HEMT structure with GaN cap. Analysis of the threshold voltage dependence on Al₂O₃ thickness for both MOS-HEMT structures suggests that (i) positive charge, which compensates the surface polarization, is not necessarily formed during the growth of III-N heterostructure, and (ii) its density is similar to the total surface polarization charge of the GaN/AlGaN barrier, rather than surface polarization of the top GaN layer only. Some constraints for the positive surface compensating charge are discussed.

  17. Water desalination via capacitive deionization

    OpenAIRE

    Suss, M. E.; Porada, S.; Sun, X.; Biesheuvel, P. M.; Yoon, J.; Presser, V.

    2015-01-01

    Capacitive deionization (CDI) is an emerging technology for the facile removal of charged ionic species from aqueous solutions, and is currently being widely explored for water desalination applications. The technology is based on ion electrosorption at the surface of a pair of electrically charged electrodes, commonly composed of highly porous carbon materials. The CDI community has grown exponentially over the past decade, driving tremendous advances via new cell architectures and system de...

  18. Charge Efficiency: A Functional Tool to Probe the Double-Layer Structure Inside of Porous Electrodes and Application in the Modeling of Capacitive Deionization

    NARCIS (Netherlands)

    Zhao, R.; Biesheuvel, P.M.; Miedema, H.; Bruning, H.; Wal, van der A.

    2010-01-01

    Porous electrodes are important in many physical-chemical processes including capacitive deionization (CDI), a desalination technology where ions are adsorbed from solution into the electrostatic double layers formed at the electrode/solution interface inside of two juxtaposed porous electrodes. A k

  19. False capacitance of supercapacitors

    OpenAIRE

    Ragoisha, G. A.; Aniskevich, Y. M.

    2016-01-01

    Capacitance measurements from cyclic voltammetry, galvanostatic chronopotentiometry and calculation of capacitance from imaginary part of impedance are widely used in investigations of supercapacitors. The methods assume the supercapacitor is a capacitor, while real objects correspond to different equivalent electric circuits and show various contributions of non-capacitive currents to the current which is used for calculation of capacitance. Specific capacitances which are presented in F g-1...

  20. Capacitance enhancement via electrode patterning.

    Science.gov (United States)

    Ho, Tuan A; Striolo, Alberto

    2013-11-28

    The necessity of increasing the energy density in electric double layer capacitors to meet current demand is fueling fundamental and applied research alike. We report here molecular dynamics simulation results for aqueous electrolytes near model electrodes. Particular focus is on the effect of electrode patterning on the structure of interfacial electrolytes, and on the potential drop between the solid electrodes and the bulk electrolytes. The latter is estimated by numerically integrating the Poisson equation using the charge densities due to water and ions accumulated near the interface as input. We considered uniform and patterned electrodes, both positively and negatively charged. The uniformly charged electrodes are modeled as graphite. The patterned ones are obtained by removing carbon atoms from the top-most graphene layer, yielding nanoscopic squares and stripes patterns. For simplicity, the patterned electrodes are effectively simulated as insulators (the charge remains localized on the top-most layer of carbon atoms). Our simulations show that the patterns alter the structure of water and the accumulation of ions at the liquid-solid interfaces. Using aqueous NaCl solutions, we found that while the capacitance calculated for three positively charged electrodes did not change much, that calculated for the negatively charged electrodes significantly increased upon patterning. We find that both water structure and orientation, as well as ion accumulation affect the capacitance. As electrode patterning affects differently water structure and ion accumulation, it might be possible to observe ion-specific effects. These results could be useful for advancing our understanding of electric double layer capacitors, capacitive desalination processes, as well as of fundamental interfacial electrolytes properties. PMID:24289370

  1. Dissecting graphene capacitance in electrochemical cell

    International Nuclear Information System (INIS)

    Quantum capacitance of graphene plays a significant role for graphene's applications in electrochemical devices and sensors, while the determination of these basic characters of Dirac point, Fermi energy, quantum capacitance, etc is still a subject of considerable debate in both experiments and simulations. Here, we report joint first-principles/continuum calculations (JFPCCs) on a monolayer graphene electrode immersed in an electrolyte coupled with a reference electrode under an applied potential. The JFPCCs gave the Fermi level, charge density on graphene, Dirac point energy, electrostatic potential, electric double layer etc as a function of the applied potential with respect to the reference electrode. These results revealed the strongly coupled relationship between Fermi level change and Dirac point shift in electrochemical cell. The total capacitance of the electrochemical cell was dissected into the quantum capacitance of the graphene electrode and the capacitance of the electric double layer. Furthermore, simple and analytic formulas were proposed for the three capacitances, which predicted, in sufficient accuracy, the behavior of capacitance versus potential. These findings deepen the understanding of quantum capacitance of graphene, which will stimulate novel experimental and theoretical studies and boost the applications of graphene in electrochemical and energy areas

  2. Mesoscopic Capacitance Oscillations

    OpenAIRE

    Buttiker, Markus; Nigg, Simon

    2006-01-01

    We examine oscillations as a function of Fermi energy in the capacitance of a mesoscopic cavity connected via a single quantum channel to a metallic contact and capacitively coupled to a back gate. The oscillations depend on the distribution of single levels in the cavity, the interaction strength and the transmission probability through the quantum channel. We use a Hartree-Fock approach to exclude self-interaction. The sample specific capacitance oscillations are in marked contrast to the c...

  3. Human body capacitance: static or dynamic concept? [ESD

    DEFF Research Database (Denmark)

    Jonassen, Niels M

    1998-01-01

    A standing human body insulated from ground by footwear and/or floor covering is in principle an insulated conductor and has, as such, a capacitance, i.e. the ability to store a charge and possibly discharge the stored energy in a spark discharge. In the human body, the human body capacitance (HBC......) is traditionally chosen as 100 pF. However, a simple geometric model seems to suggest considerably higher values. A series of experiments, where the capacitance of standing persons were determined for various combinations of footwear and floor coverings, gave values in the order of 100-150 pF when the capacitance...

  4. Quantum capacitance of graphene in contact with metal

    International Nuclear Information System (INIS)

    We report a versatile computation method to quantitatively determine the quantum capacitance of graphene when it is in contact with metal. Our results bridge the longstanding gap between the theoretically predicted and experimentally measured quantum capacitance of graphene. Contrary to popular assumptions, the presence of charged impurities or structural distortions of graphene are not the only sources of the asymmetric capacitance with respect to the polarity of the bias potential and the higher-than-expected capacitance at the Dirac point. They also originate from the field-induced electronic interactions between graphene and metal. We also provide an improved model representation of a metal–graphene junction

  5. Fringe Capacitance of a Parallel-Plate Capacitor.

    Science.gov (United States)

    Hale, D. P.

    1978-01-01

    Describes an experiment designed to measure the forces between charged parallel plates, and determines the relationship among the effective electrode area, the measured capacitance values, and the electrode spacing of a parallel plate capacitor. (GA)

  6. Variable Synthetic Capacitance

    Science.gov (United States)

    Kleinberg, L. L.

    1986-01-01

    Feedback amplifier circuit synthesizes electronically variable capacitance. Variable Synthetic Capacitor is amplifier circuit with follower/feedback configuration. Effective input capacitance depends on input set current. If synthetic capacitor is connected across resonant element of oscillator, oscillator frequency controlled via input set current. Circuit especially suitable for fine frequency adjustments of piezoelectric-crystal or inductor/capacitor resonant oscillators.

  7. Characterization and Modeling of Subfemtofarad Nanowire Capacitance Using the CBCM Technique

    OpenAIRE

    Zhao, Hui; Kim, Raseong; Paul, Abhijeet; Luisier, Mathieu; Klimeck, Gerhard; Ma, Fa-Jun; Rustagi, Subhash; Ganesh S. Samudra; Singh, Navab; Lo, Guo-Qiang; Kwong, Dim-Lee

    2009-01-01

    The experimental characterization of gate capacitance in nanoscale devices is challenging. We report an application of the charge-based capacitance measurement (CBCM) technique to measure the gate capacitance of a single-channel nanowire transistor. The measurement results are validated by 3-D electrostatic computations for parasitic estimation and 2-D self-consistent sp(3)s*d5 tight-binding computations for intrinsic gate capacitance calculations. The device simulation domains were construct...

  8. Characterization and Modeling of Subfemotofarad Nanowire Capacitance Using the CBCM Technique

    OpenAIRE

    Zhao, Hui; Kim, Raseong; Paul, Abhijeet; Luisier, Mathieu; Klimeck, Gerhard; Ma, Fa-Jun; Rustagi, Subhash C.; Ganesh S. Samudra; Singh, Navab; Lo, Guo-Qiang; Kwong, Dim-Lee

    2009-01-01

    The experimental characterization of gate capacitance in nanoscale devices is challenging. We report an application of the charge-based capacitance measurement (CBCM) technique to measure the gate capacitance of a single-channel nanowire transistor. The measurement results are validated by 3-D electrostatic computations for parasitic estimation and 2-D self-consistent sp3s∗d5 tight-binding computations for intrinsic gate capacitance calculations. The device simulation domains were constructed...

  9. Capacitance-Power-Hysteresis Trilemma in Nanoporous Supercapacitors

    Science.gov (United States)

    Lee, Alpha A.; Vella, Dominic; Goriely, Alain; Kondrat, Svyatoslav

    2016-04-01

    Nanoporous supercapacitors are an important player in the field of energy storage that fill the gap between dielectric capacitors and batteries. The key challenge in the development of supercapacitors is the perceived trade-off between capacitance and power delivery. Current efforts to boost the capacitance of nanoporous supercapacitors focus on reducing the pore size so that they can only accommodate a single layer of ions. However, this tight packing compromises the charging dynamics and hence power density. We show via an analytical theory and Monte Carlo simulations that charging is sensitively dependent on the affinity of ions to the pores, and that high capacitances can be obtained for ionophobic pores of widths significantly larger than the ion diameter. Our theory also predicts that charging can be hysteretic with a significant energy loss per cycle for intermediate ionophilicities. We use these observations to explore the parameter regimes in which a capacitance-power-hysteresis trilemma may be avoided.

  10. High Voltage Bi-directional Flyback Converter for Capacitive Actuator

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    This paper presents a high voltage DC-DC converter topology for bi-directional energy transfer between a low voltage DC source and a high voltage capacitive load. The topology is a bi-directional flyback converter with variable switching frequency control during the charge mode, and constant...... switching frequency control during the discharge mode. The converter is capable of charging the capacitive load from 24 V DC source to 2.5 kV, and discharges it to 0 V. The flyback converter has been analyzed in detail during both charge and discharge modes, by considering all the parasitic elements...... in the converter, including the most dominating parameters of the high voltage transformer viz., self-capacitance and leakage inductance. The specific capacitive load for this converter is a dielectric electro active polymer (DEAP) actuator, which can be used as an effective replacement for conventional actuators...

  11. Improved capacitance sensor with variable operating frequency for scanning capacitance microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Joonhyung [PSIA Corporation, Induspia 5F, Sang-Daewon-Dong 517-13, Sungnam 462-120 (Korea, Republic of); Kim, Joonhui [PSIA Corporation, Induspia 5F, Sang-Daewon-Dong 517-13, Sungnam 462-120 (Korea, Republic of); Jeong, Jong-Hwa [PSIA Corporation, Induspia 5F, Sang-Daewon-Dong 517-13, Sungnam 462-120 (Korea, Republic of); Lee, Euy-Kyu [Department of Physics, Myongji University, Yongin, Kyunggido 449-728 (Korea, Republic of); Seok Kim, Yong [PSIA Corporation, Induspia 5F, Sang-Daewon-Dong 517-13, Sungnam 462-120 (Korea, Republic of); Kang, Chi Jung [Department of Physics, Myongji University, Yongin, Kyunggido 449-728 (Korea, Republic of); Park, Sang-il [PSIA Corporation, Induspia 5F, Sang-Daewon-Dong 517-13, Sungnam 462-120 (Korea, Republic of)]. E-mail: park@psia.co.kr

    2005-11-15

    Scanning capacitance microscopy (SCM) has been gaining attention for its capability to measure local electrical properties in doping profile, oxide thickness, trapped charges and charge dynamics. In many cases, stray capacitance produced by different samples and measurement conditions affects the resonance frequency of a capacitance sensor. The applications of conventional SCM are critically limited by the fixed operating frequency and lack of tunability in its SCM sensor. In order to widen SCM application to various samples, we have developed a novel SCM sensor with variable operating frequency. By performing variable frequency sweep over the band of 160 MHz, the SCM sensor is tuned to select the best and optimized resonance frequency and quality factor for each sample measurement. The fundamental advantage of the new variable frequency SCM sensor was demonstrated in the SCM imaging of silicon oxide nano-crystals. Typical sensitivity of the variable frequency SCM sensor was found to be 10{sup -19} F/V.

  12. Improved capacitance sensor with variable operating frequency for scanning capacitance microscopy

    International Nuclear Information System (INIS)

    Scanning capacitance microscopy (SCM) has been gaining attention for its capability to measure local electrical properties in doping profile, oxide thickness, trapped charges and charge dynamics. In many cases, stray capacitance produced by different samples and measurement conditions affects the resonance frequency of a capacitance sensor. The applications of conventional SCM are critically limited by the fixed operating frequency and lack of tunability in its SCM sensor. In order to widen SCM application to various samples, we have developed a novel SCM sensor with variable operating frequency. By performing variable frequency sweep over the band of 160 MHz, the SCM sensor is tuned to select the best and optimized resonance frequency and quality factor for each sample measurement. The fundamental advantage of the new variable frequency SCM sensor was demonstrated in the SCM imaging of silicon oxide nano-crystals. Typical sensitivity of the variable frequency SCM sensor was found to be 10-19 F/V

  13. Capacitive chemical sensor

    Science.gov (United States)

    Manginell, Ronald P; Moorman, Matthew W; Wheeler, David R

    2014-05-27

    A microfabricated capacitive chemical sensor can be used as an autonomous chemical sensor or as an analyte-sensitive chemical preconcentrator in a larger microanalytical system. The capacitive chemical sensor detects changes in sensing film dielectric properties, such as the dielectric constant, conductivity, or dimensionality. These changes result from the interaction of a target analyte with the sensing film. This capability provides a low-power, self-heating chemical sensor suitable for remote and unattended sensing applications. The capacitive chemical sensor also enables a smart, analyte-sensitive chemical preconcentrator. After sorption of the sample by the sensing film, the film can be rapidly heated to release the sample for further analysis. Therefore, the capacitive chemical sensor can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

  14. System for Measuring Capacitance

    Science.gov (United States)

    McNichol, Randal S. (Inventor)

    2001-01-01

    A system has been developed for detecting the level of a liquid in a tank wherein a capacitor positioned in the tank has spaced plates which are positioned such that the dielectric between the plates will be either air or the liquid, depending on the depth of the liquid in the tank. An oscillator supplies a sine wave current to the capacitor and a coaxial cable connects the capacitor to a measuring circuit outside the tank. If the cable is very long or the capacitance to be measured is low, the capacitance inherent in the coaxial cable will prevent an accurate reading. To avoid this problem, an inductor is connected across the cable to form with the capacitance of the cable a parallel resonant circuit. The impedance of the parallel resonant circuit is infinite, so that attenuation of the measurement signal by the stray cable capacitance is avoided.

  15. Capacitance pressure sensor

    Science.gov (United States)

    Eaton, William P.; Staple, Bevan D.; Smith, James H.

    2000-01-01

    A microelectromechanical (MEM) capacitance pressure sensor integrated with electronic circuitry on a common substrate and a method for forming such a device are disclosed. The MEM capacitance pressure sensor includes a capacitance pressure sensor formed at least partially in a cavity etched below the surface of a silicon substrate and adjacent circuitry (CMOS, BiCMOS, or bipolar circuitry) formed on the substrate. By forming the capacitance pressure sensor in the cavity, the substrate can be planarized (e.g. by chemical-mechanical polishing) so that a standard set of integrated circuit processing steps can be used to form the electronic circuitry (e.g. using an aluminum or aluminum-alloy interconnect metallization).

  16. Nonlinear Quantum Capacitance

    OpenAIRE

    Wang, B; Zhao, X; Guo, H; Wang, J.

    1999-01-01

    We analyze the nonlinear voltage dependence of electrochemical capacitance for nanoscale conductors. This voltage dependence is due to the finite density of states of the conductors. Within Hartree theory we derive an exact expression for the electrochemical capacitance–voltage curve for a parallel plate system. The result suggests a quantum scanning capacitance microscopy at the nanoscale: by inverting the capacitance–voltage expression one is able to deduce the local spectral function of th...

  17. Quantum capacitance: a microscopic derivation

    OpenAIRE

    Mukherjee, Sreemoyee; MANNINEN, M; Deo, P. Singha

    2010-01-01

    We start from microscopic approach to many body physics and show the analytical steps and approximations required to arrive at the concept of quantum capacitance. These approximations are valid only in the semi-classical limit and the quantum capacitance in that case is determined by Lindhard function. The effective capacitance is the geometrical capacitance and the quantum capacitance in series, and this too is established starting from a microscopic theory.

  18. Correcting For Capacitance In Tests Of Solar Cells

    Science.gov (United States)

    Mueller, Robert L.

    1995-01-01

    Modified procedure for testing solar photovoltaic cells and modified software for processing test data provide corrections for effects of cell capacitance. Procedure and software needed because (a) some photovoltaic devices (for example, silicon solar cells with back-surface field region) store minority charge carriers in cell junction and thus exhibit significant capacitance, (b) capacitance affects current-vs.-voltage (I-V) measurements made when transient load connected to cell, and (c) transient load used in unmodified version of test procedure. Corrected I-V curve obtained in test of solar cell according to modified procedure approximates true cell voltage vs. cell current more closely.

  19. Quantum inductance and negative electrochemical capacitance at finite frequency

    OpenAIRE

    Wang, J.; Wang, B. G.; Guo, H

    2007-01-01

    We report on theoretical investigations of frequency dependent quantum capacitance. It is found that at finite frequency a quantum capacitor can be characterized by a classical RLC circuit with three parameters: a static electrochemical capacitance, a charge relaxation resistance, and a quantum inductance. The quantum inductance is proportional to the characteristic time scale of electron dynamics and due to its existence, the time dependent current can accumulate a phase delay and becomes la...

  20. Capacitive Coupling in Double-Circuit Transmission Lines

    Directory of Open Access Journals (Sweden)

    Zdenka Benesova

    2004-01-01

    Full Text Available The paper describes an algorithm for calculation of capacitances and charges on conductors in systems with earth wires and in double-circuit overhead lines with respect to phase arrangement. A balanced voltage system is considered. A suitable transposition of individual conductors enables to reduce the electric and magnetic fields in vicinity of overhead lines and to limit the inductive and capacitive linkage. The procedure is illustrated on examples the results of which lead to particular recommendations for designers.

  1. Comprehensive characterization of interface and oxide states in metal/oxide/semiconductor capacitors by pulsed mode capacitance and differential isothermal capacitance spectroscopy

    OpenAIRE

    Muret, Pierre

    2014-01-01

    In metal/insulator/semi-conductor structures, capacitance-voltage characteristics and capacitance or voltage transients can be measured in different conditions, which are described and implemented. Each method contains information about charges which are accommodated, captured or emitted by energy levels or bands at interface and inside the oxide. Pulsed capacitance measurements and differential isothermal procedures are analysed and performed. Calibration of the energy scale from the interfa...

  2. Membrane capacitive deionization

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Wal, van der A.

    2010-01-01

    Membrane capacitive deionization (MCDI) is an ion-removal process based on applying an electrical potential difference across an aqueous solution which flows in between oppositely placed porous electrodes, in front of which ion-exchange membranes are positioned. Due to the applied potential, ions ar

  3. Steerable Capacitive Proximity Sensor

    Science.gov (United States)

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Steerable capacitive proximity sensor of "capaciflector" type based partly on sensing units described in GSC-13377 and GSC-13475. Position of maximum sensitivity adjusted without moving sensor. Voltage of each driven shield adjusted separately to concentrate sensing electric field more toward one side or other.

  4. Digital capacitance measuring system

    Science.gov (United States)

    1973-01-01

    The hardware phase of a digital capacitance measuring system is presented with the major emphasis placed on the electrical design and operation. Test results are included of the three units fabricated. The system's interface is applicable to existing requirements for the space shuttle vehicle.

  5. A robust parasitic-insensitive successive approximation capacitance-to-digital converter

    KAUST Repository

    Omran, Hesham

    2014-09-01

    In this paper, we present a capacitive sensor digital interface circuit using true capacitance-domain successive approximation that is independent of supply voltage. Robust operation is achieved by using a charge amplifier stage and multiple comparison technique. The interface circuit is insensitive to parasitic capacitances, offset voltages, and charge injection, and is not prone to noise coupling. The proposed design achieves very low temperature sensitivity of 25ppm/oC. A coarse-fine programmable capacitance array allows digitizing a wide capacitance range of 16pF with 12.5-bit quantization limited resolution in a compact area of 0.07mm2. The fabricated prototype is experimentally verified using on-chip sensor and off-chip MEMS capacitive pressure sensor. © 2014 IEEE.

  6. Design of Capacitance to Voltage Converter for Capacitive Sensor Transducer

    Directory of Open Access Journals (Sweden)

    A. H.M.Z. Alam

    2010-01-01

    Full Text Available Problem statement: The design of Capacitance to Voltage Converter (CVC for capacitive sensor transducer was presented. The proposed design will reduce the size, power consumption and supply voltage of the circuit and can be used in high frequency band transducer. Approach: The design was implemented using the Operational amplifier (Op amp and capacitive network. The circuit was simulated using the PSPICE model parameters based on standard 0.13 μm CMOS process. Results: The design was able to measure a wide range of capacitance variations for the capacitive transducer. The performance analysis of the design showed desirable performance parameters in terms of response, low power consumption and a linear output voltage within the wide range of capacitive transducer capacitance variation for the power supply voltage of 1.2 V was achieved. Conclusion/Recommendations: The output voltage of the circuit varied linearly with the variation of capacitive transducer capacitance variation. The improved converter was compact and robust for integration into capacitive measuring systems and suitable for use in environment that making use of higher frequency band.

  7. Winding Capacitance Dividing Method for Powerformer

    Institute of Scientific and Technical Information of China (English)

    TIAN Qing; LIN Xiang-ning; LI Jian-jian; TAO Yong-hong

    2008-01-01

    It presents a method which can equivalently arrange the capacitance distribution along with the winding ofthe generator on the terminal and neutral respectively in a reasonable partition, particularly for a type of high-voltagegraded insulated cable wound generator, Powerformer. The winding of the Powerformer adopts graded insulation,which leads to the various cable thicknesses in different portion of the winding, and thus, the uneven capacitancedistribution. The large capacitive currents and large transient outrush currents resulting from the cable consisting ofthe stator winding of Powerformer may cause problems to the generator differential protection. Most of literatures a-vailable in the field of compensated differential protection focus on the charging current compensation for long trans-mission line, instead of for generator. The authors give a method which can be used to compensate the capacitivecurrent wholly to improve the reliability of the differential protection of Powerformer. It is proved that the distribu-ted capacitance can be equivalent as the lump circuit with a capacitance partition coefficient p, and p is proved as aconstant no matter whether the generator experiences the normal operation, external phase(s) fault or internal phase(s) fault. The formula of the partition coefficient is provided and the corresponding equivalent circuit of the Power-former cable to calculate capacitance currents is given. An analysis programming resolving the minimum value of thecoefficient p is written in MATLAB 7. 0/m according to this formula, using the function fmincon() which can workin any type of constraint condition. The program always gets the same global minimum points under the different in-itial values condition which proves our point by mathematical test. With this new approach to winding capacitancedividing method, the protection scheme used for Powerformer can be validated and improved accordingly.

  8. Electrical capacitance clearanceometer

    Science.gov (United States)

    Hester, Norbert J. (Inventor); Hornbeck, Charles E. (Inventor); Young, Joseph C. (Inventor)

    1992-01-01

    A hot gas turbine engine capacitive probe clearanceometer is employed to measure the clearance gap or distance between blade tips on a rotor wheel and its confining casing under operating conditions. A braze sealed tip of the probe carries a capacitor electrode which is electrically connected to an electrical inductor within the probe which is inserted into a turbine casing to position its electrode at the inner surface of the casing. Electrical power is supplied through a voltage controlled variable frequency oscillator having a tuned circuit in which the probe is a component. The oscillator signal is modulated by a change in electrical capacitance between the probe electrode and a passing blade tip surface while an automatic feedback correction circuit corrects oscillator signal drift. A change in distance between a blade tip and the probe electrode is a change in capacitance therebetween which frequency modulates the oscillator signal. The modulated oscillator signal which is then processed through a phase detector and related circuitry to provide an electrical signal is proportional to the clearance gap.

  9. Effect of stress on the membrane capacitance of the auditory outer hair cell.

    OpenAIRE

    Iwasa, K H

    1993-01-01

    The membrane capacitance of the outer hair cell, which has unique membrane potential-dependent motility, was monitored during application of membrane tension. It was found that the membrane capacitance of the cell decreased when stress was applied to the membrane. This result is the opposite of stretching the lipid bilayer in the plasma membrane. It thus indicates the importance of some other capacitance component that decreases on stretching. It has been known that charge movement across the...

  10. The noise analysis and optimum filtering techniques for a two-dimensional position sensitive orthogonal strip gamma ray detector employing resistive charge division

    International Nuclear Information System (INIS)

    The analysis of an orthogonal strip, two-dimensional position sensitive high purity germanium gamma ray detector is discussed. Position sensitivity is obtained by connecting each electrode strip on the detector to a resistor network. Charge, entering the network, divides in relation to the resistance between its entry point and the virtual earth points of the charge sensitive preamplifiers located at the end of each resistor network. The difference of the voltage pulses at the output of each preamplifier is proportional to the position at which the charge entered the resistor network and the sum of the pulse is proportional to the energy of the detected gamma ray. The analysis and spatial noise resolution is presented for this type of position sensitive detector. The results of the analysis show that the position resolution is proportional to the square root of the filter amplifier's output pulse time constant and that for energy measurement the resolution is maximized at the filter amplifier's noise corner time constant. The design of the electronic noise filtering system for the prototype gamma ray camera was based on the mathematical energy and spatial resolution equations. For the spatial channel a Gaussian trapezoidal filtering system was developed. Gaussian filtering was used for the energy channel. The detector noise model was verified by taking rms noise measurements of the filtered energy and spatial pulses from resistive readout charge dividing detectors. These measurements were within 10% of theory. (Auth.)

  11. The polarizability and the capacitance change of a bounded object in a parallel plate capacitor

    Science.gov (United States)

    Kristensson, Gerhard

    2012-09-01

    A method for solving the change in capacitance (or charge) if an object is introduced in a parallel plate capacitor is developed. The integral representation of the potential is exploited in a systematic way to solve the potential everywhere inside the capacitor. In particular, the change in capacitance is extracted. The method shows similarities with the null field approach for solving dynamic problems.

  12. Last-passage Monte Carlo algorithm for mutual capacitance.

    Science.gov (United States)

    Hwang, Chi-Ok; Given, James A

    2006-08-01

    We develop and test the last-passage diffusion algorithm, a charge-based Monte Carlo algorithm, for the mutual capacitance of a system of conductors. The first-passage algorithm is highly efficient because it is charge based and incorporates importance sampling; it averages over the properties of Brownian paths that initiate outside the conductor and terminate on its surface. However, this algorithm does not seem to generalize to mutual capacitance problems. The last-passage algorithm, in a sense, is the time reversal of the first-passage algorithm; it involves averages over particles that initiate on an absorbing surface, leave that surface, and diffuse away to infinity. To validate this algorithm, we calculate the mutual capacitance matrix of the circular-disk parallel-plate capacitor and compare with the known numerical results. Good agreement is obtained.

  13. Capacitance of circular patch resonator

    Energy Technology Data Exchange (ETDEWEB)

    Miano, G.; Verolino, L. [Dip. di Ingegneria Elettrica, Ist. Nazionale di Fisica Nucleare, Naples (Italy); Panariello, G. [Dip. di Ingegneria Elettronica, Naples (Italy); Vaccaro, V.G. [Ist. Nazionale di Fisica Nucleare, Naples (Italy). Dipt. di Scienze Fisiche

    1995-11-01

    In this paper the capacitance of the circular microstrip patch resonator is computed. It is shown that the electrostatic problem can be formulated as a system of dual integral equations, and the most interesting techniques of solutions of these systems are reviewed. Some useful approximated formulas for the capacitance are derived and plots of the capacitance are finally given in a wide range of dielectric constants.

  14. Improved Capacitive Liquid Sensor

    Science.gov (United States)

    Waldman, Francis A.

    1992-01-01

    Improved capacitive sensor used to detect presence and/or measure thickness of layer of liquid. Electrical impedance or admittance of sensor measured at prescribed frequency, and thickness of liquid inferred from predetermined theoretical or experimental relationship between impedance and thickness. Sensor is basically a three-terminal device. Features interdigitated driving and sensing electrodes and peripheral coplanar ground electrode that reduces parasitic effects. Patent-pending because first to utilize ground plane as "shunting" electrode. System less expensive than infrared, microwave, or refractive-index systems. Sensor successfully evaluated in commercial production plants to characterize emulsions, slurries, and solutions.

  15. RF-MEMS capacitive switches with high reliability

    Science.gov (United States)

    Goldsmith, Charles L.; Auciello, Orlando H.; Carlisle, John A.; Sampath, Suresh; Sumant, Anirudha V.; Carpick, Robert W.; Hwang, James; Mancini, Derrick C.; Gudeman, Chris

    2013-09-03

    A reliable long life RF-MEMS capacitive switch is provided with a dielectric layer comprising a "fast discharge diamond dielectric layer" and enabling rapid switch recovery, dielectric layer charging and discharging that is efficient and effective to enable RF-MEMS switch operation to greater than or equal to 100 billion cycles.

  16. Carbon nanotube yarns as strong flexible conductive capacitive electrodes

    NARCIS (Netherlands)

    Liu, F.; Wagterveld, R.M.; Gebben, B.; Otto, M.J.; Biesheuvel, P.M.; Hamelers, H.V.M.

    2015-01-01

    Carbon nanotube (CNT) yarn, consisting of 23 µm diameter CNT filaments, can be used as capacitive electrodes that are long, flexible, conductive and strong, for applications in energy and electrochemical water treatment. We measure the charge storage capacity as function of salt concentration, and u

  17. Programmable electronic synthesized capacitance

    Science.gov (United States)

    Kleinberg, Leonard L. (Inventor)

    1987-01-01

    A predetermined and variable synthesized capacitance which may be incorporated into the resonant portion of an electronic oscillator for the purpose of tuning the oscillator comprises a programmable operational amplifier circuit. The operational amplifier circuit has its output connected to its inverting input, in a follower configuration, by a network which is low impedance at the operational frequency of the circuit. The output of the operational amplifier is also connected to the noninverting input by a capacitor. The noninverting input appears as a synthesized capacitance which may be varied with a variation in gain-bandwidth product of the operational amplifier circuit. The gain-bandwidth product may, in turn, be varied with a variation in input set current with a digital to analog converter whose output is varied with a command word. The output impedance of the circuit may also be varied by the output set current. This circuit may provide very small ranges in oscillator frequency with relatively large control voltages unaffected by noise.

  18. A novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances

    Institute of Scientific and Technical Information of China (English)

    Dong Linxi; Chen Jindan; Yan Haixia; Huo Weihong; Li Yongjie; Sun Lingling

    2009-01-01

    The comb capacitances fabricated by deep reactive ion etching (RIE) process have high aspect ratio which is usually smaller than 30 : 1 for the complicated process factors, and the combs are usually not parallel due to the well-known micro-loading effect and other process factors, which restricts the increase of the seismic mass by increasing the thickness of comb to reduce the thermal mechanical noise and the decrease of the gap of the comb capacitances for increasing the sensitive capacitance to reduce the electrical noise. Aiming at the disadvantage of the deep RIE, a novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances is developed. One part of sensing of inertial signal of the micro-accelerometer is by the grid strip capacitances whose overlapping area is variable and which do not have the non-parallel plate's effect caused by the deep RIE process. Another part is by the sensing gap alterable capacitances whose gap between combs can be reduced by the actuators. The designed initial gap of the alterable comb capacitances is relatively large to depress the effect of the maximum aspect ratio (30 : 1) of deep RIE process. The initial gap of the capacitance of the actuator is smaller than the one of the comb capacitances. The difference between the two gaps is the initial gap of the sensitive capacitor. The designed structure depresses greatly the requirement of deep RIE process. The effects of non-parallel combs on the accelerometer are also analyzed. The characteristics of the micro-accelerometer are discussed by field emission microscopy (FEM) tool ANSYS. The tested devices based on slide-film damping effect are fabricated, and the tested quality factor is 514, which shows that grid strip capacitance design can partly improve the resolution and also prove the feasibility of the designed silicon-glass anodically bonding process.

  19. Capacitance switching in SiO 2 thin film embedded with Ge nanocrystals caused by ultraviolet illumination

    OpenAIRE

    Fung, S.; Yang, M; Chen, TP; Ding, L.; Liu, Y.; Zhu, FR

    2009-01-01

    A structure of indium tin oxide/ SiO 2 embedded with Ge nanocrystal (nc-Ge) /p-Si substrate was fabricated. The capacitance of the structure can be switched to a high-capacitance or low-capacitance state by an ultraviolet (UV) illumination. The increase (or decrease) in the capacitance is accompanied with the decrease (or increase) in the oxide resistance. The capacitance switching is explained in terms of the UV illumination-induced charging and discharging in the nc-Ge. © 2009 American Inst...

  20. Recent advances in understanding the capacitive storage in microporous carbons

    Energy Technology Data Exchange (ETDEWEB)

    Daffos, B.; Taberna, P.L. [Universite de Toulouse, CIRIMAT, UMR-CNRS 5085, Toulouse (France); Gogotsi, Y. [Department of Materials Science and Engineering, A.J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, PA (United States); Simon, P.

    2010-10-15

    This paper presents a review of our recent work on capacitance of carbide-derived carbons (CDCs). Specific capacitance as high as 14 {mu}F cm{sup -2} or 160 F g{sup -1} was achieved using CDCs with tailored subnanometer pore size, which is significantly higher than 6 {mu}F cm{sup -2} or 100 F g{sup -1} for conventional activated carbons. Such high capacitance was obtained in several types of organic electrolytes with or without solvent. A maximum is obtained for the carbons with the mean pore size close to the bare ion size, ruling out the traditional point of view that mesoporosity is highly required for maximum capacitance. Surprisingly, carbons with subnanometer porosity exhibit high capacitance retention, since only a 10% loss is measured when 6 A g{sup -1} discharge is drawn. These findings show the importance of fitting the ion size with the mean pore size. The double layer theory falls short to explain such charge storage mechanisms at the nanometer scale; thus atomistic modelling is required to find out an alternative charge storage model. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  1. Low-Temperature Scanning Capacitance Probe for Imaging Electron Motion

    International Nuclear Information System (INIS)

    Novel techniques to probe electronic properties at the nanoscale can shed light on the physics of nanoscale devices. In particular, studying the scattering of electrons from edges and apertures at the nanoscale and imaging the electron profile in a quantum dot, have been of interest [1]. In this paper, we present the design and implementation of a cooled scanning capacitance probe that operates at liquid He temperatures to image electron waves in nanodevices. The conducting tip of a scanned probe microscope is held above the nanoscale structure, and an applied sample-to-tip voltage creates an image charge that is measured by a cooled charge amplifier [2] adjacent to the tip. The circuit is based on a low-capacitance, high- electron-mobility transistor (Fujitsu FHX35X). The input is a capacitance bridge formed by a low capacitance pinched-off HEMT transistor and tip-sample capacitance. We have achieved low noise level (0.13 e/VHz) and high spatial resolution (100 nm) for this technique, which promises to be a useful tool to study electronic behavior in nanoscale devices

  2. Optimal pricing of capacitated networks

    NARCIS (Netherlands)

    Grigoriev, Alexander; Loon, van Joyce; Sitters, René; Uetz, Marc

    2009-01-01

    We address the algorithmic complexity of a profit maximization problem in capacitated, undirected networks. We are asked to price a set of $m$ capacitated network links to serve a set of $n$ potential customers. Each customer is interested in purchasing a network connection that is specified by a si

  3. Concentric Coplanar Capacitive Sensor System with Quantitative Model

    Science.gov (United States)

    Bowler, Nicola (Inventor); Chen, Tianming (Inventor)

    2014-01-01

    A concentric coplanar capacitive sensor includes a charged central disc forming a first electrode, an outer annular ring coplanar with and outer to the charged central disc, the outer annular ring forming a second electrode, and a gap between the charged central disc and the outer annular ring. The first electrode and the second electrode may be attached to an insulative film. A method provides for determining transcapacitance between the first electrode and the second electrode and using the transcapacitance in a model that accounts for a dielectric test piece to determine inversely the properties of the dielectric test piece.

  4. Negative capacitance for ultra-low power computing

    Science.gov (United States)

    Khan, Asif Islam

    Owing to the fundamental physics of the Boltzmann distribution, the ever-increasing power dissipation in nanoscale transistors threatens an end to the almost-four-decade-old cadence of continued performance improvement in complementary metal-oxide-semiconductor (CMOS) technology. It is now agreed that the introduction of new physics into the operation of field-effect transistors---in other words, "reinventing the transistor'"--- is required to avert such a bottleneck. In this dissertation, we present the experimental demonstration of a novel physical phenomenon, called the negative capacitance effect in ferroelectric oxides, which could dramatically reduce power dissipation in nanoscale transistors. It was theoretically proposed in 2008 that by introducing a ferroelectric negative capacitance material into the gate oxide of a metal-oxide-semiconductor field-effect transistor (MOSFET), the subthreshold slope could be reduced below the fundamental Boltzmann limit of 60 mV/dec, which, in turn, could arbitrarily lower the power supply voltage and the power dissipation. The research presented in this dissertation establishes the theoretical concept of ferroelectric negative capacitance as an experimentally verified fact. The main results presented in this dissertation are threefold. To start, we present the first direct measurement of negative capacitance in isolated, single crystalline, epitaxially grown thin film capacitors of ferroelectric Pb(Zr0.2Ti0.8)O3. By constructing a simple resistor-ferroelectric capacitor series circuit, we show that, during ferroelectric switching, the ferroelectric voltage decreases, while the stored charge in it increases, which directly shows a negative slope in the charge-voltage characteristics of a ferroelectric capacitor. Such a situation is completely opposite to what would be observed in a regular resistor-positive capacitor series circuit. This measurement could serve as a canonical test for negative capacitance in any novel

  5. Capacitive deionization system

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, J. H., LLNL

    1996-10-01

    The new capacitive deionization system (CDI) removes ions, contaminants impurities from water and other aqueous process streams, and further selectively places the removed ions back into solution during regeneration. It provides a separation process that does not utilize chemical regeneration processes, and thus significantly reduces or completely eliminates secondary wastes associated with the operation of ion exchange resins. In the CDI, electrolyte flows in open channels formed between adjacent electrodes, and consequently the pressure drop is much lower than conventional separation processes. The fluid flow can be gravity fed through these open channels, and does not require membranes. This feature represents a significant advantage over the conventional reverse osmosis systems which include water permeable cellulose acetate membranes, and over the electrodialysis systems which require expensive and exotic ion exchange membranes. The CDI is adaptable for use in a wide variety of commercial applications, including domestic water softening, industrial water softening, waste water purification, sea water desalination, treatment of nuclear and aqueous wastes, treatment of boiler water in nuclear and fossil power plants, production of high-purity water for semiconductor processing, and removal of salt from water for agricultural irrigation. CDI accomplishes this removal of impurities by a variety of mechanisms, but predominantly by electrostatic removal of organic and inorganic ions from water or any other dielectric solvent.

  6. Influence of Interface Traps and Electron-Hole Puddles on Quantum Capacitance and Conductivity in Graphene Field-Effect Transistors

    OpenAIRE

    Zebrev, G. I.; Melnik, E. V.; Tselykovskiy, A. A.

    2010-01-01

    We study theoretically an influence of the near-interfacial insulator traps and electron-hole puddles on the small-signal capacitance and conductance characteristics of the gated graphene structures. Based on the self-consistent electrostatic consideration and taking into account the interface trap capacitance the explicit analytic expressions for charge carrier density and the quantum capacitance as functions of the gate voltage were obtained. This allows to extract the interface trap capaci...

  7. Capacitive Position Sensor For Accelerometer

    Science.gov (United States)

    Vanzandt, Thomas R.; Kaiser, William J.; Kenny, Thomas W.

    1995-01-01

    Capacitive position sensor measures displacement of proof mass in prototype accelerometer described in "Single-Crystal Springs for Accelerometers" (NPO-18795). Sensor is ultrasensitive, miniature device operating at ultra-high frequency and described in more detail in "Ultra-High-Frequency Capacitive Displacement Sensor," (NPO-18675). Advances in design and fabrication of prototype accelerometer also applicable to magnetometers and other sensors in which sensed quantities measured in terms of deflections of small springs.

  8. Fully integrated low-noise readout circuit with automatic offset cancellation loop for capacitive microsensors.

    Science.gov (United States)

    Song, Haryong; Park, Yunjong; Kim, Hyungseup; Cho, Dong-Il Dan; Ko, Hyoungho

    2015-10-14

    Capacitive sensing schemes are widely used for various microsensors; however, such microsensors suffer from severe parasitic capacitance problems. This paper presents a fully integrated low-noise readout circuit with automatic offset cancellation loop (AOCL) for capacitive microsensors. The output offsets of the capacitive sensing chain due to the parasitic capacitances and process variations are automatically removed using AOCL. The AOCL generates electrically equivalent offset capacitance and enables charge-domain fine calibration using a 10-bit R-2R digital-to-analog converter, charge-transfer switches, and a charge-storing capacitor. The AOCL cancels the unwanted offset by binary-search algorithm based on 10-bit successive approximation register (SAR) logic. The chip is implemented using 0.18 μm complementary metal-oxide-semiconductor (CMOS) process with an active area of 1.76 mm². The power consumption is 220 μW with 3.3 V supply. The input parasitic capacitances within the range of -250 fF to 250 fF can be cancelled out automatically, and the required calibration time is lower than 10 ms.

  9. Fully Integrated Low-Noise Readout Circuit with Automatic Offset Cancellation Loop for Capacitive Microsensors

    Directory of Open Access Journals (Sweden)

    Haryong Song

    2015-10-01

    Full Text Available Capacitive sensing schemes are widely used for various microsensors; however, such microsensors suffer from severe parasitic capacitance problems. This paper presents a fully integrated low-noise readout circuit with automatic offset cancellation loop (AOCL for capacitive microsensors. The output offsets of the capacitive sensing chain due to the parasitic capacitances and process variations are automatically removed using AOCL. The AOCL generates electrically equivalent offset capacitance and enables charge-domain fine calibration using a 10-bit R-2R digital-to-analog converter, charge-transfer switches, and a charge-storing capacitor. The AOCL cancels the unwanted offset by binary-search algorithm based on 10-bit successive approximation register (SAR logic. The chip is implemented using 0.18 μm complementary metal-oxide-semiconductor (CMOS process with an active area of 1.76 mm2. The power consumption is 220 μW with 3.3 V supply. The input parasitic capacitances within the range of −250 fF to 250 fF can be cancelled out automatically, and the required calibration time is lower than 10 ms.

  10. Thermodynamic cycle analysis for capacitive deionization.

    Science.gov (United States)

    Biesheuvel, P M

    2009-04-01

    Capacitive deionization (CDI) is an ion removal technology based on temporarily storing ions in the polarization layers of two oppositely positioned electrodes. Here we present a thermodynamic model for the minimum work required for ion separation in the fully reversible case by describing the ionic solution as an ideal gas of pointlike particles. The work input is fully utilized to decrease the entropy of the outflowing streams compared to that of the inflow. Based on the Gouy-Chapman-Stern (GCS) model for planar diffuse polarization layers-with and without including additional ion volume constraints in the diffuse part of the double layer-we analyze the electric work input during charging and the work output during discharging, for a reversible charging-discharging cycle. We present a graphical thermodynamic cycle analysis for the reversible net work input during one full cycle of batchwise operation of CDI based on the charge-voltage relations for different ionic strengths. For the GCS model, an analytical solution is derived for the charge efficiency Lambda, which is the number of salt molecules removed per electron transferred from one electrode to the other. Only in the high voltage limit and for an infinite Stern layer capacity does Lambda approach unity. PMID:19167009

  11. Tracking cancer cell proliferation on a CMOS capacitance sensor chip.

    Science.gov (United States)

    Prakash, Somashekar Bangalore; Abshire, Pamela

    2008-05-15

    We report a novel technique for assessing cell proliferation that employs integrated capacitance sensors for monitoring the growth of anchorage-dependent living cells. The sensors measure substrate coupling capacitances of cells cultured on-chip in a standard in vitro environment. The biophysical phenomenon underlying the capacitive behavior of cells is the counterionic polarization around the insulating cell bodies when exposed to weak, low frequency electric fields. The sensors employ charge sharing for mapping sensed capacitance values in the fF range to output voltage signals. The sensor chip has been fabricated in a commercially available 0.5microm, 2-poly 3-metal CMOS technology. We report experimental results demonstrating sensor response to the adhesion of MDA-MB-231 breast cancer cells followed by their proliferation on the chip surface. On-chip capacitance sensing offers a non-invasive, label-free, easy-to-use, miniaturized technique with real-time monitoring capability for tracking cell proliferation in vitro. PMID:18281207

  12. The concept of chemical capacitance, A critique.

    OpenAIRE

    Trissl, H. W.

    1981-01-01

    The concept of chemical capacitance as introduced by Hong and Mauzerall (Proc. Natl. Acad. Sci. U.S.A. 1974. 71:1564) is critically reexamined. This novel capacitance was introduced to explain the time-course of flash-induced photocurrents observed in lipid bilayer membranes containing porphyrins. According to Hong and Mauzerall, the chemical capacitance results from a combination of three fundamental capacitances: the geometric membrane capacitance and the two interfacial double layer capaci...

  13. New testing procedures of a capacitive deionization reactor.

    Science.gov (United States)

    García-Quismondo, Enrique; Gómez, Roberto; Vaquero, Fernando; Cudero, Ana López; Palma, Jesús; Anderson, Marc

    2013-05-28

    Currently, according to conventional charge-discharge profiles, energy consumed in charging Capacitive Deionization (CDI) systems is always a function of different parameters (current used for charging, capacitance and current employed for discharging) making it difficult to separate the effect of these parameters on CDI performance and energy efficiency. Thus, energy efficiencies are strongly influenced by the current in the preceding charge or discharge stage of the process. We find consistently that this phenomenon, which to our knowledge has not been addressed in previous CDI communications, is much more intense when different currents are applied for each of the charging and discharging cycles. The investigation reported here provides a mechanistic analysis of the operational aspects of CDI and develops a new procedure that allows for a precise evaluation of performance and energy efficiency. Furthermore, the model developed here allows one to separate charge and discharge cycles, and therefore contributes to the possibility of defining an operational mode for real-world devices in which effective separation of deionization and regeneration steps needs to be implemented. This method of analysis could be useful not only for CDI but also for other electrochemical systems such as in secondary batteries and supercapacitors where charge and discharge are typically employed. PMID:23591701

  14. Mesoporous carbon microspheres with high capacitive performances for supercapacitors

    International Nuclear Information System (INIS)

    Highlights: • Small mesopores-enriched porous carbon microspheres were easily synthesized. • Small mesopores offer high ion-accessible surface area and facilitated ion diffusion. • The porous carbon exhibited a high specific capacitance and a good power property. - Abstract: Novel small-mesopores-enriched porous carbon microspheres have been synthesized from carbonaceous polysaccharide microspheres, by using the associated lithium acetate treating and heat treating strategies. X-ray diffraction, scanning electron microscope, transmission electron microscopy and nitrogen adsorption-desorption techniques have been employed to investigate the as-prepared samples. The analysis results indicate that the porous carbon microspheres has a high specific surface area of 1163 m2 g−1 and a satisfactory small mesoporous texture (2∼5 nm), with the mean pore size of 3.24 nm and the pore volume ratio of 2∼5 nm pores up to 92%. The capacitive performances of the samples in 6 mol L−1 KOH aqueous electrolyte, have been tested by cyclic voltammetry, electrochemical impedance spectroscopy and charge-discharge techniques. A specific capacitance of 171.5 F/g is obtained for the porous carbon microspheres via charge-discharge at a current density of 1000 mA/g. It also displayed a very high cycle stability of 97.8%, compared with the initial capacitance, after 1000 cycles at the high current density of 1000 mA/g

  15. An integrated energy-efficient capacitive sensor digital interface circuit

    KAUST Repository

    Omran, Hesham

    2014-06-19

    In this paper, we propose an energy-efficient 13-bit capacitive sensor interface circuit. The proposed design fully relies on successive approximation algorithm, which eliminates the need for oversampling and digital decimation filtering, and thus low-power consumption is achieved. The proposed architecture employs a charge amplifier stage to acheive parasitic insensitive operation and fine absolute resolution. Moreover, the output code is not affected by offset voltages or charge injection. The successive approximation algorithm is implemented in the capacitance-domain using a coarse-fine programmable capacitor array, which allows digitizing wide capacitance range in compact area. Analysis for the maximum achievable resolution due to mismatch is provided. The proposed design is insensitive to any reference voltage or current which translates to low temperature sensitivity. The operation of a prototype fabricated in a standard CMOS technology is experimentally verified using both on-chip and off-chip capacitive sensors. Compared to similar prior work, the fabricated prototype achieves and excellent energy efficiency of 34 pJ/step.

  16. Energy consumption in membrane capacitive deionization for different water recoveries and flow rates, and comparison with reverse osmosis

    NARCIS (Netherlands)

    Zhao, R.; Porada, S.; Biesheuvel, P.M.; Wal, van der A.

    2013-01-01

    Membrane capacitive deionization (MCDI) is a non-faradaic, capacitive technique for desalinating brackish water by adsorbing ions in charged porous electrodes. To compete with reverse osmosis, the specific energy consumption of MCDI needs to be reduced to less than 1 kWh per m3 of freshwater produce

  17. Coexistence of magneto-resistance and -capacitance tunability in Sm2Ga2Fe2O9

    OpenAIRE

    Wu, Ye

    2016-01-01

    We propose that charge gradient resulting in the coexisting magneto-resistance and-capacitance tunability in material systems. We have experimentally observed coexisting of tunable magneto-resistance and -capacitance in Sm2Ga2Fe2O9. Our model fits well with the experimental result.

  18. Proportional microvolume capacitive liquid level sensor array.

    Science.gov (United States)

    Seliskar, D; Waterbury, R; Kearney, R

    2005-01-01

    A sensor array has been developed for use with laboratory automation to permit closed-loop control of liquid levels in a multiwell microplate geometry. We extended a simple electrical model for non-contact capacitance-based fluid sensors to describe a fluid-level dependency. The new model shows that a charge-transfer based capacitance transducer, employing a liquid-specific calibration, can be used to obtain an output signal that varies linearly with the liquid level. The calibration also compensates for liquid-to-liquid conductivity and permittivity differences. A prototype 3×3 sensor array was built and tested using NaCl and ethanol solutions to simulate the range of conductivity and permittivity typical in biological and chemical research. Calibrated output signals were linear with liquid volume for all tested solutions (R2>0.92). Measurement error averaged 1.3 % (2.0 μl) with a standard deviation of 6.0% (9.0 μl). These results demonstrate the feasibility of developing a microvolume sensor array in essentially any M×N microplate geometry. PMID:17281955

  19. A capacitive electrode with fast recovery feature

    International Nuclear Information System (INIS)

    Capacitive electrodes (CEs) allow for acquiring biopotentials without galvanic contact, avoiding skin preparation and the use of electrolytic gel. The signal quality provided by present CEs is similar to that of standard wet electrodes, but they are more sensitive to electrostatic charge interference and motion artifacts, mainly when biopotentials are picked up through clothing and coupling capacitances are reduced to tens of picofarads. When artifacts are large enough to saturate the preamplifier, several seconds (up to tens) are needed to recover a proper baseline level, and during this period biopotential signals are irremediably lost. To reduce this problem, a CE that includes a fast-recovery (FR) circuit is proposed. It works directly on the coupling capacitor, recovering the amplifier from saturation while preserving ultra-high input impedance, as a CE requires. A prototype was built and tested acquiring ECG signals. Several experimental data are presented, which show that the proposed circuit significantly reduces record segment losses due to amplifier saturation when working in real environments. (paper)

  20. PERSONNEL DIVISION BECOMES HUMAN RESOURCES DIVISION

    CERN Multimedia

    Division des ressources humaines

    2000-01-01

    In the years to come, CERN faces big challenges in the planning and use of human resources. At this moment, Personnel (PE) Division is being reorganised to prepare for new tasks and priorities. In order to accentuate the purposes of the operation, the name of the division has been changed into Human Resources (HR) Division, with effect from 1st January 2000. Human Resources DivisionTel.73222

  1. A New Fully Differential CMOS Capacitance to Digital Converter for Lab-on-Chip Applications.

    Science.gov (United States)

    Nabovati, Ghazal; Ghafar-Zadeh, Ebrahim; Mirzaei, Maryam; Ayala-Charca, Giancarlo; Awwad, Falah; Sawan, Mohamad

    2015-06-01

    In this paper, we present a new differential CMOS capacitive sensor for Lab-on-Chip applications. The proposed integrated sensor features a DC-input ΣΔ capacitance to digital converter (CDC) and two reference and sensing microelectrodes integrated on the top most metal layer in 0.35 μm CMOS process. Herein, we describe a readout circuitry with a programmable clocking strategy using a Charge Based Capacitance Measurement technique. The simulation and experimental results demonstrate a high capacitive dynamic range of 100 fF-110 fF, the sensitivity of 350 mV/fF and the minimum detectable capacitance variation of as low as 10 aF. We also demonstrate and discuss the use of this device for environmental applications through various chemical solvents. PMID:25134090

  2. Anomalous capacitance characteristics of TFTs with LDD structures in the saturation region

    Science.gov (United States)

    Kim, Miryeon; Sun, Wookyung; Shin, Minho; Kim, Kiwoo; Kang, Jongseuk; Shin, Hyungsoon

    2016-05-01

    The effect of lightly doped drain (LDD) doping concentration on the capacitance of a low-temperature polycrystalline silicon (LTPS) thin-film transistor (TFT) is investigated. An anomalous gate-to-source capacitance phenomenon is observed: first, the capacitance decreases, and then it increases according to the gate voltage in the saturation region. This phenomenon is not affected by the subgap density-of-states and arises as the doping concentration of the LDD region is reduced. To investigate the effects of each source and the drain LDD dose on the gate-to-source capacitance, two-dimensional device simulations were conducted in which each dose of the source and drain LDD was changed individually. The reduced controllability of the source voltage to the gate charge in the saturation region due to the increased resistance of the source LDD region with low LDD dose is identified as the reason for this anomalous capacitance phenomenon.

  3. Anomalous capacitance characteristics of TFTs with LDD structures in the saturation region

    International Nuclear Information System (INIS)

    The effect of lightly doped drain (LDD) doping concentration on the capacitance of a low-temperature polycrystalline silicon (LTPS) thin-film transistor (TFT) is investigated. An anomalous gate-to-source capacitance phenomenon is observed: first, the capacitance decreases, and then it increases according to the gate voltage in the saturation region. This phenomenon is not affected by the subgap density-of-states and arises as the doping concentration of the LDD region is reduced. To investigate the effects of each source and the drain LDD dose on the gate-to-source capacitance, two-dimensional device simulations were conducted in which each dose of the source and drain LDD was changed individually. The reduced controllability of the source voltage to the gate charge in the saturation region due to the increased resistance of the source LDD region with low LDD dose is identified as the reason for this anomalous capacitance phenomenon. (paper)

  4. Slow and fast capacitive process taking place at the ionic liquid/electrode interface.

    Science.gov (United States)

    Roling, Bernhard; Drüschler, Marcel; Huber, Benediki

    2012-01-01

    Electrochemical impedance spectroscopy was used to characterise the interface between the ultrapure room temperature ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate and a Au(111) working electrode at electrode potentials more positive than the open circuit potential (-0.14 V vs. Pt pseudo-reference). Plots of the potential-dependent data in the complex capacitance plane reveal the existence of a fast and a slow capacitive process. In order to derive the contribution of both processes to the overall capacitance, the complex capacitance data were fitted using an empirical Cole-Cole equation. The differential capacitance of the fast process is almost constant between -0.14 V and +0.2 V (vs. Pt pseudo-reference) and decreases at more positive potentials, while the differential capacitance of the slower process exhibits a maximum at +0.2 V. This maximum leads to a maximum in the overall differential capacitance. We attribute the slow process to charge redistributions in the innermost ion layer, which require an activation energy in excess of that for ion transport in the room temperature ionic liquid. The differential capacitance maximum of the slow process at +0.2 V is most likely caused by reorientations of the 1-butyl-1l-methylpyrrolidinium cations in the innermost layer with the positively charged ring moving away from the Au(111) surface and leaving behind voids which are then occupied by anions. In a recent Monte Carlo simulation by Federov, Georgi and Kornyshev (Electrochem. Commun. 2010, 12, 296), such a process was identified as the origin of a differential capacitance maximum in the anodic regime. Our results suggest that the time scales of capacitive processes at the ionic liquid/metal interface are an important piece of information and should be considered in more detail in future experimental and theoretical studies.

  5. Voltage dependence of the differential capacitance of a p+-n junction

    International Nuclear Information System (INIS)

    The dependences of the differential capacitance and current of a p+-n junction with a uniformly doped n region on the voltage in the junction region are calculated. The p+-n junction capacitance controls the charge change in the junction region taking into account a change in the electric field of the quasi-neutral n region and a change in its bipolar drift mobility with increasing excess charge-carrier concentration. It is shown that the change in the sign of the p+-n junction capacitance with increasing injection level is caused by a decrease in the bipolar drift mobility as the electron-hole pair concentration in the n region increases. It is shown that the p+-n junction capacitance decreases with increasing reverse voltage and tends to a constant positive value.

  6. Preparation and electrochemical capacitance of cobalt oxide (Co3O4) nanotubes as supercapacitor material

    International Nuclear Information System (INIS)

    Cobalt oxide (Co3O4) nanotubes have been successfully synthesized by chemically depositing cobalt hydroxide in anodic aluminum oxide (AAO) templates and thermally annealing at 500 oC. The synthesized nanotubes have been characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The electrochemical capacitance behavior of the Co3O4 nanotubes electrode was investigated by cyclic voltammetry, galvanostatic charge-discharge studies and electrochemical impedance spectroscopy in 6 mol L-1 KOH solution. The electrochemical data demonstrate that the Co3O4 nanotubes display good capacitive behavior with a specific capacitance of 574 F g-1 at a current density of 0.1 A g-1 and a good specific capacitance retention of ca. 95% after 1000 continuous charge-discharge cycles, indicating that the Co3O4 nanotubes can be promising electroactive materials for supercapacitor.

  7. Electrode design and cell operation of a capacitive deionization system

    OpenAIRE

    Sans Palacios, Gerard

    2013-01-01

    Capacitive deionization (CDI) is a promising technology for desalination in a more energy-efficiency way than conventional techniques such as membrane separation and thermal distillation. However, a rational designed structure of the electrode materials and a proper system assembling is essentially required for achieving high CDI performance. Here, carbon electrodes are studied and tested in a deionization system which is operated at and optimized for high salt adsorption and charge efficienc...

  8. What we talk about when we talk about capacitance measured with the voltage-clamp step method

    OpenAIRE

    Taylor, Adam L.

    2011-01-01

    Capacitance is a fundamental neuronal property. One common way to measure capacitance is to deliver a small voltage-clamp step that is long enough for the clamp current to come to steady state, and then to divide the integrated transient charge by the voltage-clamp step size. In an isopotential neuron, this method is known to measure the total cell capacitance. However, in a cell that is not isopotential, this measures only a fraction of the total capacitance. This has generally been thought ...

  9. Bioenergetics of Mammalian Sperm Capacitation

    Directory of Open Access Journals (Sweden)

    Alessandra Ferramosca

    2014-01-01

    Full Text Available After ejaculation, the mammalian male gamete must undergo the capacitation process, which is a prerequisite for egg fertilization. The bioenergetics of sperm capacitation is poorly understood despite its fundamental role in sustaining the biochemical and molecular events occurring during gamete activation. Glycolysis and mitochondrial oxidative phosphorylation (OXPHOS are the two major metabolic pathways producing ATP which is the primary source of energy for spermatozoa. Since recent data suggest that spermatozoa have the ability to use different metabolic substrates, the main aim of this work is to present a broad overview of the current knowledge on the energy-producing metabolic pathways operating inside sperm mitochondria during capacitation in different mammalian species. Metabolism of glucose and of other energetic substrates, such as pyruvate, lactate, and citrate, is critically analyzed. Such knowledge, besides its obvious importance for basic science, could eventually translate into the development of novel strategies for treatment of male infertility, artificial reproduction, and sperm selection methods.

  10. An Enhanced Sensing Application Based on a Flexible Projected Capacitive-Sensing Mattress

    OpenAIRE

    Wen-Ying Chang; Chi-Chun Chen; Chih-Cheng Chang; Chin-Lung Yang

    2014-01-01

    This paper presents a cost-effective sensor system for mattresses that can classify the sleeping posture of an individual and prevent pressure ulcers. This system applies projected capacitive sensing to the field of health care. The charge time (CT) method was used to sensitively and accurately measure the capacitance of the projected electrodes. The required characteristics of the projected capacitor were identified to develop large-area applications for sensory mattresses. The area of the e...

  11. Ultrananocrystalline diamond films with optimized dielectric properties for advanced RF MEMS capacitive switches

    Science.gov (United States)

    Sumant, Anirudha V.; Auciello, Orlando H.; Mancini, Derrick C.

    2013-01-15

    An efficient deposition process is provided for fabricating reliable RF MEMS capacitive switches with multilayer ultrananocrystalline (UNCD) films for more rapid recovery, charging and discharging that is effective for more than a billion cycles of operation. Significantly, the deposition process is compatible for integration with CMOS electronics and thereby can provide monolithically integrated RF MEMS capacitive switches for use with CMOS electronic devices, such as for insertion into phase array antennas for radars and other RF communication systems.

  12. Remarkably high value of Capacitance in BiFeO3 Nanorod

    OpenAIRE

    Dutta, Nabanita; Bandyopadhyay, S K; Rana, Subhasis; Sen, Pintu; Himanshu, A. K.

    2013-01-01

    A remarkably high value of specific capacitance of 450 F/g has been observed through electrochemical measurements in the electrode made of multiferroic Bismuth Ferrite (BFO) in the form of nanorods protruding out. These BFO nanorods were developed on porous Anodised Alumina (AAO) templates using wet chemical technique. Diameters of nanorods were in the range of 20-100 nm. The high capacitance is attributed to the nanostructure. The active surface charge has been evaluated electrochemically by...

  13. Improving capacitance/damping ratio in a capacitive MEMS transducer

    International Nuclear Information System (INIS)

    Damping forces play an important role in capacitive MEMS (microelectromechanical systems) behavior, and typical damper design (parallel-plates) cannot address the design conflict between increase in electrical capacitance and damping reduction. Squeeze-film damping in in-plane parallel-plate MEMS is discussed here and a novel damper geometry for gap-varying parallel-plates is introduced and used to increase the capacitance/damping ratio. The new geometry is compared with a typical parallel-plate design for an silicon-on-insulator process (25 µm thick) and experimental data shows an approximate 25% to 50% reduction for the damping coefficient in structures with 500 µm long dampers (for a gap variation between 0.75 and 3.75 µm), in agreement with computational fluid dynamics simulations, without significantly affecting the capacitance value (∼4% reduction). Preliminary simulations to study the role of the different geometric parameters involved in the improved geometry are also performed and reveal that the channel width is the most critical value for effective damping reduction. (paper)

  14. Large capacitance enhancement induced by metal-doping in graphene-based supercapacitors: a first-principles-based assessment.

    Science.gov (United States)

    Paek, Eunsu; Pak, Alexander J; Hwang, Gyeong S

    2014-08-13

    Chemically doped graphene-based materials have recently been explored as a means to improve the performance of supercapacitors. In this work, we investigate the effects of 3d transition metals bound to vacancy sites in graphene with [BMIM][PF6] ionic liquid on the interfacial capacitance; these results are compared to the pristine graphene case with particular attention to the relative contributions of the quantum and electric double layer capacitances. Our study highlights that the presence of metal-vacancy complexes significantly increases the availability of electronic states near the charge neutrality point, thereby enhancing the quantum capacitance drastically. In addition, the use of metal-doped graphene electrodes is found to only marginally influence the microstructure and capacitance of the electric double layer. Our findings indicate that metal-doping of graphene-like electrodes can be a promising route toward increasing the interfacial capacitance of electrochemical double layer capacitors, primarily by enhancing the quantum capacitance. PMID:24983127

  15. Driven shielding capacitive proximity sensor

    Science.gov (United States)

    Vranish, John M. (Inventor); McConnell, Robert L. (Inventor)

    2000-01-01

    A capacitive proximity sensing element, backed by a reflector driven at the same voltage as and in phase with the sensor, is used to reflect the field lines away from a grounded robot arm towards an intruding object, thus dramatically increasing the sensor's range and sensitivity.

  16. Capacitive Proximity Sensor Has Longer Range

    Science.gov (United States)

    Vranish, John M.

    1992-01-01

    Capacitive proximity sensor on robot arm detects nearby object via capacitive effect of object on frequency of oscillator. Sensing element part of oscillator circuit operating at about 20 kHz. Total capacitance between sensing element and ground constitutes tuning capacitance of oscillator. Sensor circuit includes shield driven by replica of alternating voltage applied to sensing element. Driven shield concentrates sensing electrostatic field in exterior region to enhance sensitivity to object. Sensitivity and dynamic range has corresponding 12-to-1 improvement.

  17. Active Targets For Capacitive Proximity Sensors

    Science.gov (United States)

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Lightweight, low-power active targets devised for use with improved capacitive proximity sensors described in "Capacitive Proximity Sensor Has Longer Range" (GSC-13377), and "Capacitive Proximity Sensors With Additional Driven Shields" (GSC-13475). Active targets are short-distance electrostatic beacons; they generate known alternating electro-static fields used for alignment and/or to measure distances.

  18. Biology and Medicine Division: Annual report 1986

    Energy Technology Data Exchange (ETDEWEB)

    1987-04-01

    The Biology and Medicine Division continues to make important contributions in scientific areas in which it has a long-established leadership role. For 50 years the Division has pioneered in the application of radioisotopes and charged particles to biology and medicine. There is a growing emphasis on cellular and molecular applications in the work of all the Division's research groups. The powerful tools of genetic engineering, the use of recombinant products, the analytical application of DNA probes, and the use of restriction fragment length polymorphic DNA are described and proposed for increasing use in the future.

  19. Biology and Medicine Division: Annual report 1986

    International Nuclear Information System (INIS)

    The Biology and Medicine Division continues to make important contributions in scientific areas in which it has a long-established leadership role. For 50 years the Division has pioneered in the application of radioisotopes and charged particles to biology and medicine. There is a growing emphasis on cellular and molecular applications in the work of all the Division's research groups. The powerful tools of genetic engineering, the use of recombinant products, the analytical application of DNA probes, and the use of restriction fragment length polymorphic DNA are described and proposed for increasing use in the future

  20. Effects of stray capacitance to ground in bipolar water impedance measurements based on capacitive electrodes

    OpenAIRE

    Pallàs Areny, Ramon; Aliau Bonet, Carles

    2015-01-01

    Liquid impedance measurements based on capacitive (or contactless) electrodes Overcome electrode polarization problems but are affected by stray capacitance from the material being measured to ground, the same as measurements with direct-contact electrodes. This study shows that the effects of that capacitance depend on the impedance being measured and for bipolar impedance measurements they increase when the ratio between that stray capacitance and lectrode capacitance increases.

  1. Energy recovery in membrane capacitive deionization.

    Science.gov (United States)

    Długołęcki, Piotr; van der Wal, Albert

    2013-05-01

    Membrane capacitive deionization (MCDI) is a water desalination technology based on applying a cell voltage between two oppositely placed porous carbon electrodes. In front of each electrode, an ion-exchange membrane is positioned, and between them, a spacer is situated, which transports the water to be desalinated. In this work, we demonstrate for the first time that up to 83% of the energy used for charging the electrodes during desalination can be recovered in the regeneration step. This can be achieved by charging and discharging the electrodes in a controlled manner by using constant current conditions. By implementing energy recovery as an integral part of the MCDI operation, the overall energy consumption can be as low as 0.26 (kW·h)/m(3) of produced water to reduce the salinity by 10 mM, which means that MCDI is more energy efficient for treatment of brackish water than reverse osmosis. Nevertheless, the measured energy consumption is much higher than the thermodynamically calculated values for desalinating the water, and therefore, a further improvement in thermodynamic efficiency will be needed in the future. PMID:23477563

  2. Mechano-capacitive properties of polarized membranes.

    Science.gov (United States)

    Mosgaard, Lars D; Zecchi, Karis A; Heimburg, Thomas

    2015-10-28

    Biological membranes are capacitors that can be charged by applying a field across the membrane. The charges on the capacitor exert a force on the membrane that leads to electrostriction, i.e. a thinning of the membrane. Since the force is quadratic in voltage, negative and positive voltage have an identical influence on the physics of symmetric membranes. However, this is not the case for a membrane with an asymmetry leading to a permanent electric polarization. Positive and negative voltages of identical magnitude lead to different properties. Such an asymmetry can originate from a lipid composition that is different on the two monolayers of the membrane, or from membrane curvature. The latter effect is called 'flexoelectricity'. As a consequence of permanent polarization, the membrane capacitor is discharged at a voltage different from zero. This leads to interesting electrical phenomena such as outward or inward rectification of membrane permeability. Here, we introduce a generalized theoretical framework, that treats capacitance, polarization, flexoelectricity, piezoelectricity and thermoelectricity in the same language. We show applications to electrostriction, membrane permeability and piezoelectricity and thermoelectricity close to melting transitions, where such effects are especially pronounced. PMID:26324950

  3. Instabilities in a capacitively coupled oxygen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Küllig, C., E-mail: kuellig@physik.uni-greifswald.de; Wegner, Th., E-mail: physics@thwegner.com; Meichsner, J., E-mail: meichsner@physik.uni-greifswald.de [Institute of Physics, University of Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany)

    2015-04-15

    Periodic fluctuations in the frequency range from 0.3 to 3 kHz were experimentally investigated in capacitively coupled radio frequency (13.56 MHz) oxygen plasma. The Gaussian beam microwave interferometry directly provides the line integrated electron density fluctuations. A system of two Langmuir probes measured the floating potential spatially (axial, radial) and temporally resolved. Hence, the floating potential fluctuation development is mapped within the discharge volume and provides a kind of discharge breathing and no wave propagation. Finally, it was measured the optical emission pattern of atomic oxygen during the fluctuation as well as the RF phase resolved optical emission intensity at selected phase position of the fluctuation by an intensified charge-coupled device camera. The deduced excitation rate pattern reveals the RF sheath dynamics and electron heating mechanisms, which is changing between low and high electronegativity during a fluctuation cycle. A perturbation calculation was taken into account using a global model with 15 elementary collision processes in the balance equations for the charged plasma species (O{sub 2}{sup +}, e, O{sup −}, O{sub 2}{sup −}) and a harmonic perturbation. The calculated frequencies agree with the experimentally observed frequencies. Whereby, the electron attachment/detachment processes are important for the generation of this instability.

  4. Asymmetric electrode configuration for enhanced membrane capacitive deionization.

    Science.gov (United States)

    Omosebi, Ayokunle; Gao, Xin; Landon, James; Liu, Kunlei

    2014-08-13

    Long-term performance of capacitive deionization (CDI) and membrane-assisted capacitive deionization (MCDI) single cells equipped with the same pristine carbon xerogel (CX) electrodes configured as the anode and cathode was investigated. Unlike CDI, which was subject to performance degradation in a short period of time, MCDI showed performance preservation during the 50 h of operation due to its ability to mitigate charge leakage from parasitic electrochemical reactions that result in carbon oxidation. Differential capacitance measurements of the used CDI and MCDI electrodes revealed shifting of the potential of zero charge (EPZC) of the CDI anode from -0.1 to 0.4 V but only to 0.1 V for the MCDI anode. CDI and MCDI cells tested with electrodes having EPZCs at -0.1 and 0.5 V showed strongly contrasting results depending on the anode-cathode EPZC configuration. The MCDI cell configured with a 0.5 V EPZC cathode and -0.1 V EPZC anode displayed the best performance of all the tested cells, benefiting from increased counterion excess within the potential window, and the membrane was in-place to reject expelled co-ions from accessing the bulk. PMID:24985047

  5. DNA Nucleotides Detection via capacitance properties of Graphene

    Science.gov (United States)

    Khadempar, Nahid; Berahman, Masoud; Yazdanpanah, Arash

    2016-05-01

    In the present paper a new method is suggested to detect the DNA nucleotides on a first-principles calculation of the electronic features of DNA bases which chemisorbed to a graphene sheet placed between two gold electrodes in a contact-channel-contact system. The capacitance properties of graphene in the channel are surveyed using non-equilibrium Green's function coupled with the Density Functional Theory. Thus, the capacitance properties of graphene are theoretically investigated in a biological environment, and, using a novel method, the effect of the chemisorbed DNA nucleotides on electrical charges on the surface of graphene is deciphered. Several parameters in this method are also extracted including Electrostatic energy, Induced density, induced electrostatic potential, Electron difference potential and Electron difference density. The qualitative and quantitative differences among these parameters can be used to identify DNA nucleotides. Some of the advantages of this approach include its ease and high accuracy. What distinguishes the current research is that it is the first experiment to investigate the capacitance properties of gaphene changes in the biological environment and the effect of chemisorbed DNA nucleotides on the surface of graphene on the charge.

  6. Quantum capacitance in topological insulators under strain in a tilted magnetic field

    KAUST Repository

    Tahir, M.

    2012-12-06

    Topological insulators exhibit unique properties due to surface states of massless Dirac fermions with conserved time reversal symmetry. We consider the quantum capacitance under strain in an external tilted magnetic field and demonstrate a minimum at the charge neutrality point due to splitting of the zeroth Landau level. We also find beating in the Shubnikov de Haas oscillations due to strain, which originate from the topological helical states. Varying the tilting angle from perpendicular to parallel washes out these oscillations with a strain induced gap at the charge neutrality point. Our results explain recent quantum capacitance and transport experiments.

  7. Full-bridge capacitive extensometer

    Science.gov (United States)

    Peters, Randall D.

    1993-08-01

    Capacitive transducers have proven to be very effective sensors of small displacements, because of inherent stability and noninvasive high resolution. The most versatile ones have been those of a differential type, in which two elements are altered in opposite directions in response to change of the system parameter being monitored. Oftentimes, this differential pair has been incorporated into a bridge circuit, which is a useful means for employing synchronous detection to improve signal to noise ratios. Unlike previous differential capacitive dilatometers which used only two active capacitors, the present sensor is a full-bridge type, which is well suited to measuring low-level thermal expansions. This analog sensor is capable of 0.1 μm resolution anywhere within a range of several centimeters, with a linearity of 0.1%. Its user friendly output can be put on a strip chart recorder or directed to a computer for sophisticated data analysis.

  8. Quantum capacitance in topological insulators.

    Science.gov (United States)

    Xiu, Faxian; Meyer, Nicholas; Kou, Xufeng; He, Liang; Lang, Murong; Wang, Yong; Yu, Xinxin; Fedorov, Alexei V; Zou, Jin; Wang, Kang L

    2012-01-01

    Topological insulators show unique properties resulting from massless, Dirac-like surface states that are protected by time-reversal symmetry. Theory predicts that the surface states exhibit a quantum spin Hall effect with counter-propagating electrons carrying opposite spins in the absence of an external magnetic field. However, to date, the revelation of these states through conventional transport measurements remains a significant challenge owing to the predominance of bulk carriers. Here, we report on an experimental observation of Shubnikov-de Haas oscillations in quantum capacitance measurements, which originate from topological helical states. Unlike the traditional transport approach, the quantum capacitance measurements are remarkably alleviated from bulk interference at high excitation frequencies, thus enabling a distinction between the surface and bulk. We also demonstrate easy access to the surface states at relatively high temperatures up to 60 K. Our approach may eventually facilitate an exciting exploration of exotic topological properties at room temperature.

  9. An Enhanced Sensing Application Based on a Flexible Projected Capacitive-Sensing Mattress

    Directory of Open Access Journals (Sweden)

    Wen-Ying Chang

    2014-04-01

    Full Text Available This paper presents a cost-effective sensor system for mattresses that can classify the sleeping posture of an individual and prevent pressure ulcers. This system applies projected capacitive sensing to the field of health care. The charge time (CT method was used to sensitively and accurately measure the capacitance of the projected electrodes. The required characteristics of the projected capacitor were identified to develop large-area applications for sensory mattresses. The area of the electrodes, the use of shielding, and the increased length of the transmission line were calibrated to more accurately measure the capacitance of the electrodes in large-size applications. To offer the users comfort in the prone position, a flexible substrate was selected and covered with 16 × 20 electrodes. Compared with the static charge sensitive bed (SCSB, our proposed system-flexible projected capacitive-sensing mattress (FPCSM comes with more electrodes to increase the resolution of posture identification. As for the body pressure system (BPS, the FPCSM has advantages such as lower cost, higher aging-resistance capability, and the ability to sense the capacitance of the covered regions without physical contact. The proposed guard ring design effectively absorbs the noise and interrupts leakage paths. The projected capacitive electrode is suitable for proximity-sensing applications and succeeds at quickly recognizing the sleeping pattern of the user.

  10. Capacitive de-ionization electrode

    Energy Technology Data Exchange (ETDEWEB)

    Daily, III, William D.

    2013-03-19

    An electrode "cell" for use in a capacitive deionization (CDI) reactor consists of the electrode support structure, a non-reactive conductive material, the electrode accompaniment or substrate and a flow through screen/separator. These "layers" are repeated and the electrodes are sealed together with gaskets between two end plates to create stacked sets of alternating anode and cathode electrodes in the CDI reactor.

  11. High resolution capacitance detection circuit for rotor micro-gyroscope

    Directory of Open Access Journals (Sweden)

    Ming-Yuan Ren

    2014-03-01

    Full Text Available Conventional methods for rotor position detection of micro-gyroscopes include common exciting electrodes (single frequency and common sensing electrodes (frequency multiplex, but they have encountered some problems. So we present a high resolution and low noise pick-off circuit for micro-gyroscopes which utilizes the time multiplex method. The detecting circuit adopts a continuous-time current sensing circuit for capacitance measurement, and its noise analysis of the charge amplifier is introduced. The equivalent output noise power spectral density of phase-sensitive demodulation is 120 nV/Hz1/2. Tests revealed that the whole circuitry has a relative capacitance resolution of 1 × 10−8.

  12. Concentration Fluctuations and Capacitive Response in Dense Ionic Solutions

    CERN Document Server

    Uralcan, Betul; Debenedetti, Pablo G; Limmer, David T

    2016-01-01

    We use molecular dynamics simulations in a constant potential ensemble to study the effects of solution composition on the electrochemical response of a double layer capacitor. We find that the capacitance first increases with ion concentration following its expected ideal solution behavior but decreases upon approaching a pure ionic liquid. The non-monotonic behavior of the capacitance as a function of ion concentration results from the competition between the independent motion of solvated ions in the dilute regime and solvation fluctuations in the concentrated regime. When charge fluctuations induced by correlated ion-solvent fluctuations are large relative to those induced by the pure ionic liquid, such non-monotonic behavior is expected to be generic.

  13. Study of Liquid Mixtures Electrical Properties as a Function of Electrical Conductivity using Capacitive Sensor

    Directory of Open Access Journals (Sweden)

    P. Azimi Anaraki

    2014-01-01

    Full Text Available In this study design and operation of a capacitive cell sensor for liquid mixture monitoring is reported. Operation of the capacitance measurement module for such probe is based on the charge and discharge method. The capacitive effect of small drop of different liquids in tap water was studied using this capacitive sensor. A small percentage of contaminating agents such as oil in tap water is determined with a good sensitivity. Comparison of the measured resistances for different liquid mixtures shows a decrease by increasing Total Dissolved Solids (TDS. In another study the electrical capacitance of different solutions, mixture of ethanol and water, mixture of methanol and water, mixture of petroleum and water and other liquid mixtures were studied. It must be pointed out that the measuring capacitance of the sensor is different from that of the liquid capacitance, but the samples electrical characteristics can be compared relatively with each other. The effects of the electrical conductivity on the permittivity and conductance of different liquid mixtures are also investigated. The experimental results are promising concerning water liquids and verify the successful operation of such device as a liquid sensor and are a useful method for checking the electrical quality of the water mixture that is required for different applications.

  14. Facile fabrication of cobalt oxalate nanostructures with superior specific capacitance and super-long cycling stability

    Science.gov (United States)

    Cheng, Guanhua; Si, Conghui; Zhang, Jie; Wang, Ying; Yang, Wanfeng; Dong, Chaoqun; Zhang, Zhonghua

    2016-04-01

    Transition metal oxalate materials have shown huge competitive advantages for applications in supercapacitors. Herein, nanostructured cobalt oxalate supported on cobalt foils has been facilely fabricated by anodization, and could directly serve as additive/binder-free electrodes for supercapacitors. The as-prepared cobalt oxalate electrodes present superior specific capacitance of 1269 F g-1 at the current density of 6 A g-1 in the galvanostatic charge/discharge test. Moreover, the retained capacitance is as high as 87.2% as the current density increases from 6 A g-1 to 30 A g-1. More importantly, the specific capacitance of cobalt oxalate retains 91.9% even after super-long cycling of 100,000 cycles. In addition, an asymmetric supercapacitor assembled with cobalt oxalate (positive electrode) and activated carbon (negative electrode) demonstrates excellent capacitive performance with high energy density and power density.

  15. Molecular Insights into Carbon Nanotube Supercapacitors: Capacitance Independent of Voltage and Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Guang [Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemical and Biomolecular Engineering; Li, Song [Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemical and Biomolecular Engineering; Atchison, Jennifer S. [Leibniz Inst. for New Materials (INM), Saarbrücken (Germany); Presser, Volker [Leibniz Inst. for New Materials (INM), Saarbrücken (Germany); Cummings, Peter T. [Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemical and Biomolecular Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science

    2013-04-12

    Molecular dynamics (MD) simulations of supercapacitors with single-walled carbon nanotube (SWCNT) electrodes in room-temperature ionic liquids were performed to investigate the influences of the applied electrical potential, the radius/curvature of SWCNTs, and temperature on their capacitive behavior. It is found that (1) SWCNTs-based supercapacitors exhibit a near-flat capacitance–potential curve, (2) the capacitance increases as the tube radius decreases, and (3) the capacitance depends little on the temperature. We report the first MD study showing the influence of the electrode curvature on the capacitance–potential curve and negligible dependence of temperature on capacitance of tubular electrode. The latter is in good agreement with recent experimental findings and is attributed to the similarity of the electrical double layer (EDL) microstructure with temperature varying from 260 to 400 K. The electrode curvature effect is explained by the dominance of charge overscreening and increased ion density per unit area of electrode surface.

  16. High Resolution Differential Capacitance Detection Scheme for Micro Levitated Rotor Gyroscope

    Institute of Scientific and Technical Information of China (English)

    Huang Xiaogang; Chen Wenyuan; Liu Wu; Zhang Weiping; Wu Xiaosheng

    2007-01-01

    A differential capacitance detection circuit aiming at detection of rotating angle in a novel levitation structure is presented. To ensure the low non-linearity and high resolution, noise analysis and non-linearity simulation are conducted. In the capacitance interface, an integral charge amplifier is adopted as a front end amplifier to reduce the parasitic capacitance caused by connecting wire. For the novel differential capacitance bridge with a coupling capacitor, the noise floor and non-linearity of the detection circuit are analyzed, and the results show that the detecting circuit is capable of realizing angle detection with high angular resolution and relative low non-linearity.With a specially designed printed circuit board, the circuit is simulated by PSpice. The practical experiment shows that the detection board can achieve angular resolution as high as 0.04° with a non-linearity error 2.3%.

  17. Redox regulation of mammalian sperm capacitation

    Directory of Open Access Journals (Sweden)

    Cristian O′Flaherty

    2015-01-01

    Full Text Available Capacitation is a series of morphological and metabolic changes necessary for the spermatozoon to achieve fertilizing ability. One of the earlier happenings during mammalian sperm capacitation is the production of reactive oxygen species (ROS that will trigger and regulate a series of events including protein phosphorylation, in a time-dependent fashion. The identity of the sperm oxidase responsible for the production of ROS involved in capacitation is still elusive, and several candidates are discussed in this review. Interestingly, ROS-induced ROS formation has been described during human sperm capacitation. Redox signaling during capacitation is associated with changes in thiol groups of proteins located on the plasma membrane and subcellular compartments of the spermatozoon. Both, oxidation of thiols forming disulfide bridges and the increase on thiol content are necessary to regulate different sperm proteins associated with capacitation. Reducing equivalents such as NADH and NADPH are necessary to support capacitation in many species including humans. Lactate dehydrogenase, glucose-6-phospohate dehydrogenase, and isocitrate dehydrogenase are responsible in supplying NAD (P H for sperm capacitation. Peroxiredoxins (PRDXs are newly described enzymes with antioxidant properties that can protect mammalian spermatozoa; however, they are also candidates for assuring the regulation of redox signaling required for sperm capacitation. The dysregulation of PRDXs and of enzymes needed for their reactivation such as thioredoxin/thioredoxin reductase system and glutathione-S-transferases impairs sperm motility, capacitation, and promotes DNA damage in spermatozoa leading to male infertility.

  18. An approach to evaluate capacitance, capacitive reactance and resistance of pivoted pads of a thrust bearing

    Science.gov (United States)

    Prashad, Har

    1992-07-01

    A theoretical approach is developed for determining the capacitance and active resistance between the interacting surfaces of pivoted pads and thrust collar, under different conditions of operation. It is shown that resistance and capacitive reactance of a thrust bearing decrease with the number of pads times the values of these parameters for an individual pad, and that capacitance increases with the number of pads times the capacitance of an individual pad. The analysis presented has a potential to diagnose the behavior of pivoted pad thrust bearings with the angle of tilt and the ratio of film thickness at the leading to trailing edge, by determining the variation of capacitance, resistance, and capacitive reactance.

  19. Physics division annual report 2000

    International Nuclear Information System (INIS)

    This report summarizes the research performed in 2000 in the Physics Division of Argonne National Laboratory. The Division's programs include operation of ATLAS as a national user facility, nuclear structure and reaction research, nuclear theory and medium energy physics research, and accelerator research and development. As the Nuclear Science Advisory Committee and the nuclear science community create a new long range plan for the field in 2001, it is clear that the research of the Division is closely aligned with and continues to help define the national goals of our field. The NSAC 2001 Long Range Plan recommends as the highest priority for major new construction the Rare Isotope Accelerator (RIA), a bold step forward for nuclear structure and nuclear astrophysics. The accelerator R and D in the Physics Division has made major contributions to almost all aspects of the RIA design concept and the community was convinced that this project is ready to move forward. 2000 saw the end of the first Gammasphere epoch at ATLAS, One hundred Gammasphere experiments were completed between January 1998 and March 2000, 60% of which used the Fragment Mass Analyzer to provide mass identification in the reaction. The experimental program at ATLAS then shifted to other important research avenues including proton radioactivity, mass measurements with the Canadian Penning Trap and measurements of high energy gamma-rays in nuclear reactions with the MSU/ORNL/Texas A and M BaF2 array. ATLAS provided 5460 beam-research hours for user experiments and maintained an operational reliability of 95%. Radioactive beams accounted for 7% of the beam time. ATLAS also provided a crucial test of a key RIA concept, the ability to accelerate multiple charge states in a superconducting heavy-ion linac. This new capability was immediately used to increase the performance for a scheduled experiment. The medium energy program continued to make strides in examining how the quark-gluon structure of

  20. Boosting capacitive blue-energy and desalination devices with waste heat.

    Science.gov (United States)

    Janssen, Mathijs; Härtel, Andreas; van Roij, René

    2014-12-31

    We show that sustainably harvesting "blue" energy from the spontaneous mixing process of fresh and salty water can be boosted by varying the water temperature during a capacitive mixing process. Our modified Poisson-Boltzmann calculations predict a strong temperature dependence of the electrostatic potential of a charged electrode in contact with an adjacent aqueous 1:1 electrolyte. We propose to exploit this dependence to boost the efficiency of capacitive blue engines, which are based on cyclically charging and discharging nanoporous supercapacitors immersed in salty and fresh water, respectively [D. Brogioli, Phys. Rev. Lett. 103, 058501 (2009)]. We show that the energy output of blue engines can be increased by a factor of order 2 if warm (waste-heated) fresh water is mixed with cold sea water. Moreover, the underlying physics can also be used to optimize the reverse process of capacitive desalination of water.

  1. Electrochemical activation of carbon cloth in aqueous inorganic salt solution for superior capacitive performance

    Science.gov (United States)

    Ye, Dong; Yu, Yao; Tang, Jie; Liu, Lin; Wu, Yue

    2016-05-01

    Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as an electrode material for flexible supercapacitors. However, pristine CC has such a low surface area and poor electrochemical activity that the energy storage capability is usually very poor. Herein, we report a green method, two-step electrochemical activation in an aqueous solution of inorganic salts, to significantly enhance the capacitance of CC for supercapacitor application. Micro-cracks, exfoliated carbon fiber shells, and oxygen-containing functional groups (OFGs) were introduced onto the surface of the carbon filament. This resulted in an enhancement of over two orders of magnitude in capacitance compared to that of the bare CC electrode, reaching up to a maximum areal capacitance of 505.5 mF cm-2 at the current density of 6 mA cm-2 in aqueous H2SO4 electrolyte. Electrochemical reduction of CC electrodes led to the removal of most electrochemically unstable surface OFGs, resulting in superior charging/discharging rate capability and excellent cycling stability. Although the activated CC electrode contained a high-level of surface oxygen functional groups (~15 at%), it still exhibited a remarkable charging-discharging rate capability, retaining ~88% of the capacitance when the charging rate increased from 6 to 48 mA cm-2. Moreover, the activated CC electrode exhibited excellent cycling stability with ~97% capacitance remaining after 10 000 cycles at a current density of 24 mA cm-2. A symmetrical supercapacitor based on the activated CC exhibited an ideal capacitive behavior and fast charge-discharge properties. Such a simple, environment-friendly, and cost-effective strategy to activate CC shows great potential in the fabrication of high-performance flexible supercapacitors.Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as

  2. Flexible PVDF ferroelectric capacitive temperature sensor

    KAUST Repository

    Khan, Naveed

    2015-08-02

    In this paper, a capacitive temperature sensor based on polyvinylidene fluoride (PVDF) capacitor is explored. The PVDF capacitor is characterized below its Curie temperature. The capacitance of the PVDF capacitor changes vs temperature with a sensitivity of 16pF/°C. The linearity measurement of the capacitance-temperature relation shows less than 0.7°C error from a best fit straight line. An LC oscillator based temperature sensor is demonstrated based on this capacitor.

  3. Nucleotide Capacitance Calculation for DNA Sequencing

    OpenAIRE

    Lu, Jun-Qiang; Zhang, X.-G.

    2008-01-01

    Using a first-principles linear response theory, the capacitance of the DNA nucleotides, adenine, cytosine, guanine, and thymine, are calculated. The difference in the capacitance between the nucleotides is studied with respect to conformational distortion. The result suggests that although an alternate current capacitance measurement of a single-stranded DNA chain threaded through a nanogap electrode may not be sufficient to be used as a standalone method for rapid DNA sequencing, the capaci...

  4. Electrical Capacitance Volume Tomography: Design and Applications

    OpenAIRE

    Warsito Warsito; Liang-Shih Fan; Qussai Marashdeh; Fei Wang

    2010-01-01

    This article reports recent advances and progress in the field of electrical capacitance volume tomography (ECVT). ECVT, developed from the two-dimensional electrical capacitance tomography (ECT), is a promising non-intrusive imaging technology that can provide real-time three-dimensional images of the sensing domain. Images are reconstructed from capacitance measurements acquired by electrodes placed on the outside boundary of the testing vessel. In this article, a review of progress on capa...

  5. Electrochemical capacitance of a leaky nanocapacitor

    OpenAIRE

    Zhao, X; Guo, H; Wang, J.

    1999-01-01

    We report a detailed theoretical investigation on electrochemical capacitance of a nanoscale capacitor where there is a DC coupling between the two conductors. For this ``leaky'' quantum capacitor, we have derived general analytic expressions of the linear and second order nonlinear electrochemical capacitance within a first principles quantum theory in the discrete potential approximation. Linear and nonlinear capacitance coefficients are also derived in a self-consistent manner without the ...

  6. Dual Cryogenic Capacitive Density Sensor

    Science.gov (United States)

    Youngquist, Robert; Mata, Carlos; Vokrot, Peter; Cox, Robert

    2009-01-01

    A dual cryogenic capacitive density sensor has been developed. The device contains capacitive sensors that monitor two-phase cryogenic flow density to within 1% accuracy, which, if temperature were known, could be used to determine the ratio of liquid to gas in the line. Two of these density sensors, located a known distance apart, comprise the sensor, providing some information on the velocity of the flow. This sensor was constructed as a proposed mass flowmeter with high data acquisition rates. Without moving parts, this device is capable of detecting the density change within a two-phase cryogenic flow more than 100 times a second. Detection is enabled by a series of two sets of five parallel plates with stainless steel, cryogenically rated tubing. The parallel plates form the two capacitive sensors, which are measured by electrically isolated digital electronics. These capacitors monitor the dielectric of the flow essentially the density of the flow and can be used to determine (along with temperature) the ratio of cryogenic liquid to gas. Combining this information with the velocity of the flow can, with care, be used to approximate the total two-phase mass flow. The sensor can be operated at moderately high pressures and can be lowered into a cryogenic bath. The electronics have been substantially improved over the older sensors, incorporating a better microprocessor, elaborate ground loop protection and noise limiting circuitry, and reduced temperature sensitivity. At the time of this writing, this design has been bench tested at room temperature, but actual cryogenic tests are pending

  7. Detection of Telomerase Activity Using Capacitance Measurements

    Science.gov (United States)

    Kang, Bong Keun; Lee, Ri Mi; Choi, Ahmi; Jung, Hyo-Il; Yoo, Kyung-Hwa

    2007-03-01

    Telomerase activity has been found in about 85% cancer cells, while no activity observed in normal cells, so that telomerase has been proposed as a marker for cancer detection. Here, we describe electrical detection of telomerase activity using capacitance measurements. We have investigated the length dependence of capacitance on DNA solutions and found that the capacitance of DNA solutions were dependent on the DNA length. In addition, upon adding telomerase into the solution of telomeric substrate primer, the capacitance was observed to change as a function of time due to the telomeric elongation. These results suggest that this novel nanosensor may be used for rapid detection of telomerase activity.

  8. Capacitance Probe Resonator for Multichannel Electrometer

    Science.gov (United States)

    Blaes, Brent R.; Schaefer, Rembrandt T> Glaser, Robert J.

    2012-01-01

    A multichannel electrometer voltmeter has been developed that employs a mechanical resonator with voltage-sensing capacitance-probe electrodes that enable high-impedance, high-voltage, radiation-hardened measurement of an Internal Electrostatic Discharge Monitor (IESDM) sensor. The IESDM is new sensor technology targeted for integration into a Space Environmental Monitor (SEM) subsystem used for the characterization and monitoring of deep dielectric charging on spacecraft. The resonator solution relies on a non-contact, voltage-sensing, sinusoidal-varying capacitor to achieve input impedances as high as 10 petaohms as determined by the resonator materials, geometries, cleanliness, and construction. The resonator is designed with one dominant mechanical degree of freedom, so it resonates as a simple harmonic oscillator and because of the linearity of the variable sense capacitor to displacement, generates a pure sinusoidal current signal for a fixed input voltage under measurement. This enables the use of an idealized phase-lock sensing scheme for optimal signal detection in the presence of noise.

  9. Electrochemical activation of carbon cloth in aqueous inorganic salt solution for superior capacitive performance.

    Science.gov (United States)

    Ye, Dong; Yu, Yao; Tang, Jie; Liu, Lin; Wu, Yue

    2016-05-21

    Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as an electrode material for flexible supercapacitors. However, pristine CC has such a low surface area and poor electrochemical activity that the energy storage capability is usually very poor. Herein, we report a green method, two-step electrochemical activation in an aqueous solution of inorganic salts, to significantly enhance the capacitance of CC for supercapacitor application. Micro-cracks, exfoliated carbon fiber shells, and oxygen-containing functional groups (OFGs) were introduced onto the surface of the carbon filament. This resulted in an enhancement of over two orders of magnitude in capacitance compared to that of the bare CC electrode, reaching up to a maximum areal capacitance of 505.5 mF cm(-2) at the current density of 6 mA cm(-2) in aqueous H2SO4 electrolyte. Electrochemical reduction of CC electrodes led to the removal of most electrochemically unstable surface OFGs, resulting in superior charging/discharging rate capability and excellent cycling stability. Although the activated CC electrode contained a high-level of surface oxygen functional groups (∼15 at%), it still exhibited a remarkable charging-discharging rate capability, retaining ∼88% of the capacitance when the charging rate increased from 6 to 48 mA cm(-2). Moreover, the activated CC electrode exhibited excellent cycling stability with ∼97% capacitance remaining after 10 000 cycles at a current density of 24 mA cm(-2). A symmetrical supercapacitor based on the activated CC exhibited an ideal capacitive behavior and fast charge-discharge properties. Such a simple, environment-friendly, and cost-effective strategy to activate CC shows great potential in the fabrication of high-performance flexible supercapacitors. PMID:27141910

  10. Module Eleven: Capacitance; Basic Electricity and Electronics Individualized Learning System.

    Science.gov (United States)

    Bureau of Naval Personnel, Washington, DC.

    In this module the student will learn about another circuit quantity, capacitance, and discover the effects of this component on circuit current, voltage, and power. The module is divided into seven lessons: the capacitor, theory of capacitance, total capacitance, RC (resistive-capacitive circuit) time constant, capacitive reactance, phase and…

  11. Low capacitance large volume shaped-field germanium detector

    International Nuclear Information System (INIS)

    A large volume (150 cm3) germanium detector with a full- depletion capacitance of only ∼1 pf has been fabricated. The effect of impurity space-charge was utilized to obtain an appropriate electric field distribution in the detector so that carriers are collected on a small area electrode. Detectors based on this principle are capable of very low noise operation and have immediate applications in direct detection dark matter particle experiments. Detector pulse shapes and carrier trapping effects were also examined for possible applications involving higher energy radiations. 9 refs., 10 figs

  12. Capacitance Measurement with a Sigma Delta Converter for 3D Electrical Capacitance Tomography

    Science.gov (United States)

    Nurge, Mark

    2005-01-01

    This paper will explore suitability of a newly available capacitance to digital converter for use in a 3D Electrical Capacitance Tomography system. A switch design is presented along with circuitry needed to extend the range of the capacitance to digital converter. Results are then discussed for a 15+ hour drift and noise test.

  13. Quantum Fluctuation of Mesoscopic Capacitance Coupled Circuit in a Thermal Vacuum State

    Institute of Scientific and Technical Information of China (English)

    朱爱东; 张寿; 金哲; 赵永芳; 井孝功; 千正男; 苏文辉

    2003-01-01

    The quantum fluctuations of mesoscopic capacitance-coupled circuit in thermal vacuum state are investigated by using the theory of thermal field dynamics on the basis of quantization of the mesoscopic circuit. It is shown that under a definite temperature, the fluctuations of electric charges and currents change with temperature. The higher the temperature, the more quantum noise the coupled circuit exhibits.

  14. Direct prediction of the desalination performance of porous carbon electrodes for capacitive deionization

    NARCIS (Netherlands)

    Porada, S.; Borchardt, D.; Oschatz, M.; Bryjak, M.; Atchison, J.S.; Keesman, K.J.; Kaskel, S.; Biesheuvel, P.M.; Presser, V.

    2013-01-01

    Desalination by capacitive deionization (CDI) is an emerging technology for the energy- and cost-efficient removal of ions from water by electrosorption in charged porous carbon electrodes. A variety of carbon materials, including activated carbons, templated carbons, carbon aerogels, and carbon nan

  15. How Much Have Students Learned? Research-Based Teaching on Electrical Capacitance

    Science.gov (United States)

    Guisasola, Jenaro; Zubimendi, Jose L.; Zuza, Kristina

    2010-01-01

    We examine the pedagogical suitability of introducing a teaching sequence for the concept of electrical capacitance within the context of charging a body. This short sequence targets first year university students and was designed following students' common conceptions on this topic. The evaluation is made by comparing the results with a control…

  16. Investigation on the Sensitivity Distribution in Electrical Capacitance Tomography System

    Directory of Open Access Journals (Sweden)

    Pan Jiang

    2013-07-01

    Full Text Available The gas-solid-liquid three-phase flow is a very complicated flow pattern in pipeline transportation. By using electrical capacitance tomography (ETC it can acquire the permittivity distribution of the multi-phase. The sensitivity distribution in ETC may affect the analysis of the permittivity distribution of the multi-phase. However, very limited work has been done in this issue. In order to investigate the sensitivity distribution in ETC, this paper employs the finite element method (FEM to establish the principle and components of ECT. The FEM model of the sensitivity distribution as a function of the inter-electrode capacitance was discussed. Simulation tests were carried out to calculate the charge on the electrode pairs to access the potential distribution of the ETC. The analysis results show that the dielectric have great influence on the capacitance value and small distance between the electrode pair and the sensitivity field will produce high sensitivity value. Hence, the findings of this work can provide reference for the design of ECT in practice.

  17. Direct measurement of specific membrane capacitance in neurons.

    Science.gov (United States)

    Gentet, L J; Stuart, G J; Clements, J D

    2000-07-01

    The specific membrane capacitance (C(m)) of a neuron influences synaptic efficacy and determines the speed with which electrical signals propagate along dendrites and unmyelinated axons. The value of this important parameter remains controversial. In this study, C(m) was estimated for the somatic membrane of cortical pyramidal neurons, spinal cord neurons, and hippocampal neurons. A nucleated patch was pulled and a voltage-clamp step was applied. The exponential decay of the capacitative charging current was analyzed to give the total membrane capacitance, which was then divided by the observed surface area of the patch. C(m) was 0.9 microF/cm(2) for each class of neuron. To test the possibility that membrane proteins may alter C(m), embryonic kidney cells (HEK-293) were studied before and after transfection with a plasmid coding for glycine receptor/channels. The value of C(m) was indistinguishable in untransfected cells and in transfected cells expressing a high level of glycine channels, indicating that differences in transmembrane protein content do not significantly affect C(m). Thus, to a first approximation, C(m) may be treated as a "biological constant" across many classes of neuron. PMID:10866957

  18. Capacitive Feedthroughs for Medical Implants

    Science.gov (United States)

    Grob, Sven; Tass, Peter A.; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging.

  19. Ultrahigh Temperature Capacitive Pressure Sensor

    Science.gov (United States)

    Harsh, Kevin

    2014-01-01

    Robust, miniaturized sensing systems are needed to improve performance, increase efficiency, and track system health status and failure modes of advanced propulsion systems. Because microsensors must operate in extremely harsh environments, there are many technical challenges involved in developing reliable systems. In addition to high temperatures and pressures, sensing systems are exposed to oxidation, corrosion, thermal shock, fatigue, fouling, and abrasive wear. In these harsh conditions, sensors must be able to withstand high flow rates, vibration, jet fuel, and exhaust. In order for existing and future aeropropulsion turbine engines to improve safety and reduce cost and emissions while controlling engine instabilities, more accurate and complete sensor information is necessary. High-temperature (300 to 1,350 C) capacitive pressure sensors are of particular interest due to their high measurement bandwidth and inherent suitability for wireless readout schemes. The objective of this project is to develop a capacitive pressure sensor based on silicon carbon nitride (SiCN), a new class of high-temperature ceramic materials, which possesses excellent mechanical and electric properties at temperatures up to 1,600 C.

  20. QUANTUM FLUCTUATIONS IN MESOSCOPIC RESISTANCE INDUCTANCE-CAPACITANCE ELECTRIC CIRCUITS AT FINITE TEMPERATURE

    Institute of Scientific and Technical Information of China (English)

    LIANG XIAN-TING; FAN HONG-YI

    2001-01-01

    By using the charge and current in a quantization resistance-inductance-capacitance (RLC) electric circuit, we construct a pair of canonical variables. Using this pair of variables and the thermal field dynamics, we obtain the fluctuations of charge and current in the RLC electric circuit at finite temperatures. It is shown that the fluctuations increase with increasing temperature and decrease with prolonging of time.

  1. Computational Fair Division

    DEFF Research Database (Denmark)

    Branzei, Simina

    Fair division is a fundamental problem in economic theory and one of the oldest questions faced through the history of human society. The high level scenario is that of several participants having to divide a collection of resources such that everyone is satisfied with their allocation -- e.g. two...... heirs dividing a car, house, and piece of land inherited. The literature on fair division was developed in the 20th century in mathematics and economics, but computational work on fair division is still sparse. This thesis can be seen as an excursion in computational fair division divided in two parts...... study alternative and richer models, such as externalities in cake cutting, simultaneous cake cutting, and envy-free cake cutting. The second part of the thesis tackles the fair allocation of multiple goods, divisible and indivisible. In the realm of divisible goods, we investigate the well known...

  2. Variational Stabilization of MoM Solution for the Capacitance of a Conducting Plate and Nonuniform Grid Method

    Institute of Scientific and Technical Information of China (English)

    LIANGChanghong; LILong; ZHAIHuiqing; WANGLina

    2003-01-01

    Variational stabilization of the method of moments (MoM) solutions for the capacitance of a conducting plate is proved in this paper. A nonuniform grid method is presented according to a balance of reacting charges, whose solutions converge faster than uniform grid solutions. Based on variational stabilization, we point out that it is the optimal nonuniform grid that can achieve the maximum capacitance value.

  3. Division of atomic physics

    International Nuclear Information System (INIS)

    The Division of Atomic Physics, Lund Institute of Technology (LTH), is responsible for the basic physics teaching in all subjects at LTH and for specialized teaching in Optics, Atomic Physics, Atomic and Molecular Spectroscopy and Laser Physics. The Division has research activities in basic and applied optical spectroscopy, to a large extent based on lasers. It is also part of the Physics Department, Lund University, where it forms one of eight divisions. Since the beginning of 1980 the research activities of our division have been centred around the use of lasers. The activities during the period 1991-1992 is described in this progress reports

  4. Enhanced Capacitive Characteristics of Activated Carbon by Secondary Activation

    Institute of Scientific and Technical Information of China (English)

    YANG Hui; LU Tian-hong; Yoshio Masaki

    2004-01-01

    The effect of the improvement of commercial activated carbon(AC) on its specific capacitance and high rate capability of double layer(dl) charging/discharging process has been studied. The improvement of AC was carried out via a secondary activation under steam in the presence of catalyst NiCl2, and the suitable condition was found to be a heat treatment at about 875 ℃ for 1 h. Under those conditions, the discharge specific capacitance of the improved AC increases up to 53.67 F/g, showing an increase of about 25% as compared with that of as-received AC. The good rectangular-shaped voltammograms and A.C. impedance spectra prove that the high rate capability of the capacitor made of the improved AC is enhanced significantly. The capacitance resistance(RC) time constant of the capacitor containing the improved AC is 1.74 s, which is much lower than that of the one containing as-received AC(an RC value of 4. 73 s). It is noted that both kinds of AC samples show a similar specific surface area and pore size distribution, but some changes have taken place in the carbon surface groups, especially a decrease in the concentration of surface carbonyl groups after the improvement, which have been verified by means of X-photoelectron spectroscopy. Accordingly, it is suggested that the decrease in the concentration of surface carbonyl groups for the improved AC is beneficial to the organic electrolyte ion penetrating into the pores, thus leading to the increase in both the specific capacitance and high rate capability of the supercapacitor.

  5. Emitter space charge layer transit time in bipolar junction transistors

    Science.gov (United States)

    Rustagi, S. C.; Chattopadhyaya, S. K.

    1981-04-01

    The charge defined emitter space charge layer transit times of double diffused transistors have been calculated using a regional approach, and compared with the corresponding base transit times. The results obtained for emitter space-charge layer transit times have been discussed with reference to the capacitance analysis of Morgan and Smit (1960) for graded p-n junctions.

  6. Capacitive mixing power production from salinity gradient energy enhanced through exoelectrogen-generated ionic currents

    KAUST Repository

    Hatzell, Marta C.

    2014-01-01

    Several approaches to generate electrical power directly from salinity gradient energy using capacitive electrodes have recently been developed, but power densities have remained low. By immersing the capacitive electrodes in ionic fields generated by exoelectrogenic microorganisms in bioelectrochemical reactors, we found that energy capture using synthetic river and seawater could be increased ∼65 times, and power generation ∼46 times. Favorable electrochemical reactions due to microbial oxidation of organic matter, coupled to oxygen reduction at the cathode, created an ionic flow field that enabled more effective passive charging of the capacitive electrodes and higher energy capture. This ionic-based approach is not limited to the use of river water-seawater solutions. It can also be applied in industrial settings, as demonstrated using thermolytic solutions that can be used to capture waste heat energy as salinity gradient energy. Forced charging of the capacitive electrodes, using energy generated by the bioelectrochemical system and a thermolytic solution, further increased the maximum power density to 7 W m -2 (capacitive electrode). © 2014 The Royal Society of Chemistry.

  7. Energy-Efficient Capacitive-Sensor Interfaces

    NARCIS (Netherlands)

    Tan, Z.

    2013-01-01

    This thesis describes the theory, design and realization of energy-efficient capacitive-sensor interfaces that are dedicated to energy-constrained applications. The goal of this work is to explore energy-efficient capacitive-sensor interface design techniques both at the system and the circuit level

  8. Quantum capacitance of the monolayer graphene

    OpenAIRE

    Cheremisin, M. V.

    2012-01-01

    The quantum capacitance of the monolayer graphene for arbitrary carrier density, magnetic field and temperature is found. The density dependence of the quantum capacitance is analyzed for magnetic field(temperature) is fixed(varied) and vice versa. The theory is compared with the experimental data.

  9. Capacitance densitometer for flow regime identification

    Science.gov (United States)

    Shipp, Jr., Roy L.

    1978-01-01

    This invention relates to a capacitance densitometer for determining the flow regime of a two-phase flow system. A two-element capacitance densitometer is used in conjunction with a conventional single-beam gamma densitometer to unambiguously identify the prevailing flow regime and the average density of a flowing fluid.

  10. Capacitance-coupled wiper increases potentiometer life

    Science.gov (United States)

    Dimeff, J.

    1968-01-01

    Capacitively-coupled wiper reduces the friction between the sliding contact and the potentiometer element in conventional potentiometers. A small preamplifier employed close to the wiper reduces errors caused by output cable capacitance. The device is friction free with resultant low wear and has high speed and high resolution.

  11. A 45.8fJ/Step, energy-efficient, differential SAR capacitance-to-digital converter for capacitive pressure sensing

    KAUST Repository

    Alhoshany, Abdulaziz

    2016-05-03

    An energy-efficient readout circuit for a capacitive sensor is presented. The capacitive sensor is digitized by a 12-bit energy efficient capacitance-to-digital converter (CDC) that is based on a differential successive-approximation architecture. This CDC meets extremely low power requirements by using an operational transconductance amplifier (OTA) that is based on a current-starved inverter. It uses a charge-redistribution DAC that involves coarse-fine architecture. We split the DAC into a coarse-DAC and a fine-DAC to allow a wide capacitance range in a compact area. It covers a wide range of capacitance of 16.14 pF with a 4.5 fF absolute resolution. An analog comparator is implemented by cross-coupling two 3-input NAND gates to enable power and area efficient operation. The prototype CDC was fabricated using a standard 180 nm CMOS technology. The 12-bit CDC has a measurement time of 42.5 μs, and consumes 3.54 μW and 0.29 μW from analog and digital supplies, respectively. This corresponds to a state-of-the-art figure-of-merit (FoM) of 45.8 fJ/conversion-step. © 2016 Elsevier B.V. All rights reserved.

  12. Conductivity Effect on the Capacitance Measurement of a Parallel-Plate Capacitive Sensor System

    Directory of Open Access Journals (Sweden)

    Peyman Azimi

    2011-01-01

    Full Text Available In this article design and operation of a parallel-plate capacitive sensor based on the dielectric capacitance and conductance change of the gap medium is reported. The designed system was used to determine characteristics of different water liquids as a result of the capacitance variations. The air gap capacitance is measured and then by filling the gap with a liquid the capacitance is monitored for different liquids. Proposed sensor is used for the distilled, tap, boiled, and salt water measurements and the capacitance results are compared. A big difference about 45.5 :F in capacitance values for the salt and distilled water shows a high sensitivity, which can be used to recognize different water liquids. The experimental results are promising for water liquids and verify the successful operation of such a device as a liquid sensor, a useful method for checking the electrical quality of the water that is required for different applications.

  13. Power Dissipation in Division

    DEFF Research Database (Denmark)

    Liu, Wei; Nannarelli, Alberto

    2008-01-01

    A few classes of algorithms to implement division in hardware have been used over the years: division by digit-recurrence, by reciprocal approximation by iterative methods and by polynomial approximation. Due to the differences in the algorithms, a comparison among their implementation in terms...

  14. Division: The Sleeping Dragon

    Science.gov (United States)

    Watson, Anne

    2012-01-01

    Of the four mathematical operators, division seems to not sit easily for many learners. Division is often described as "the odd one out". Pupils develop coping strategies that enable them to "get away with it". So, problems, misunderstandings, and misconceptions go unresolved perhaps for a lifetime. Why is this? Is it a case of "out of sight out…

  15. Pseudo-capacitance of nanoporous carbons in pyrrolidinium-based protic ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Mysyk, R.; Raymundo-Pinero, E.; Beguin, F. [CRMD, CNRS-University, 1B rue de la Ferollerie, 45071 Orleans (France); Anouti, M.; Lemordant, D. [Universite Francois Rabelais, Laboratoire PCMB/CIME, Parc de Grandmont, 37200 Tours (France)

    2010-03-15

    Protic ionic liquids (PILs) were used as novel electrolyte for carbon-based supercapacitors. The cyclic voltammograms in three-electrode cells show reversible redox humps, revealing pseudo-faradaic charge transfer. Oxidative treatment of activated carbon enriches the surface functionality and leads to a higher capacitance owing to a stronger pseudo-faradaic contribution. The capacitors using PILs demonstrate a higher voltage window than with aqueous H{sub 2}SO{sub 4}, while keeping the same values of capacitance, and being able to operate at lower temperature. A combination of activated carbons and PILs holds promise for improving the energy characteristics of supercapacitors. (author)

  16. Thin films of pure vanadium nitride: Evidence for anomalous non-faradaic capacitance

    Science.gov (United States)

    Bondarchuk, Oleksandr; Morel, Alban; Bélanger, Daniel; Goikolea, Eider; Brousse, Thierry; Mysyk, Roman

    2016-08-01

    An impressive gravimetric capacitance of 1300 F g-1 (surface capacitance ∼3.3 mF cm-2) reported by Choi et al., 2006 for nanosized vanadium nitride has stimulated considerable interest in vanadium nitride as a potential electrode material for energy storing systems - supercapacitors. The postulated mechanism of charge storage in vanadium nitride materials involves redox reactions in the thin surface layer of vanadium oxide while the core vanadium nitride serves exclusively as a conducting platform. In this study we have synthesized pure oxygen-free vanadium nitride films and have found that they are capable of delivering a surface capacitance of up to ∼3 mF cm-2 at a potential scan rate of 3 mV s-1 and ∼2 mF cm-2 at a potential scan rate of 1 V s-1 in aqueous electrolytes. Combining electrochemical testing with X-ray photoelectron spectroscopy characterization has revealed that redox reactions play no or little role in the electrochemical response of pure VN, in contrast to the common wisdom stemming from the electrochemical response of oxygen-containing films. An alternative charge storage mechanism - space charge accumulation in a subsurface layer of ∼100 nm - was put forward to explain the experimentally observed capacitance of VN films in aqueous electrolytes.

  17. Capacitance and conductance studies on silicon solar cells subjected to 8 MeV electron irradiations

    Science.gov (United States)

    Sathyanarayana Bhat, P.; Rao, Asha; Sanjeev, Ganesh; Usha, G.; Priya, G. Krishna; Sankaran, M.; Puthanveettil, Suresh E.

    2015-06-01

    The space grade silicon solar cells were irradiated with 8 MeV electrons with doses ranging from 5-100 k Gy. Capacitance and conductance measurements were carried out in order to investigate the anomalous degradation of the cells in the radiation harsh environments and the results are presented in this paper. Detailed and systematic analysis of the frequency-dependent capacitance and conductance measurements were performed to extract the information about the interface trap states. The small increase in density of interface states was observed from the conductance-frequency measurements. The reduction in carrier concentration upon electron irradiation is due to the trapping of charge carriers by the radiation induced trap centres. The Drive Level Capacitance Profiling (DLCP) technique has been applied to study the properties of defects in silicon solar cells. A small variation in responding state densities with measuring frequency was observed and the defect densities are in the range 1015 -1016 cm-3.

  18. Capacitance variation in electrostatic energy harvester with conductive droplet moving on electret film

    International Nuclear Information System (INIS)

    This work addresses numerical finite element calculations on a droplet-based electrostatic energy harvester to reveal additional characteristics that supplement previous test results. Assumptions of 2D electrode and static droplet profile have been applied to make the simulation achievable based on the real prototype. We investigate the consequences of a uniform space charge distribution in the film. Capacitance variation and open-circuit voltage of the simulation model have been determined and display respectively maximum and minimum magnitudes when the droplet is in the middle of finger gap. The sharp variation of capacitance, during which the droplet moves from the gap centre to the finger centre, can explain the narrow peaks of output voltage seen in experiments. Additionally, the influence of droplet size on the capacitance variation is also investigated

  19. Physics division annual report - 1999

    International Nuclear Information System (INIS)

    This report summarizes the research performed in the past year in the Argonne Physics Division. The Division's programs include operation of ATLAS as a national heavy-ion user facility, nuclear structure and reaction research with beams of heavy ions, accelerator research and development especially in superconducting radio frequency technology, nuclear theory and medium energy nuclear physics. The Division took significant strides forward in its science and its initiatives for the future in the past year. Major progress was made in developing the concept and the technology for the future advanced facility of beams of short-lived nuclei, the Rare Isotope Accelerator. The scientific program capitalized on important instrumentation initiatives with key advances in nuclear science. In 1999, the nuclear science community adopted the Argonne concept for a multi-beam superconducting linear accelerator driver as the design of choice for the next major facility in the field a Rare Isotope Accelerator (RIA) as recommended by the Nuclear Science Advisory Committee's 1996 Long Range Plan. Argonne has made significant R and D progress on almost all aspects of the design concept including the fast gas catcher (to allow fast fragmentation beams to be stopped and reaccelerated) that in large part, defined the RIA concept the superconducting rf technology for the driver accelerator, the multiple-charge-state concept (to permit the facility to meet the design intensity goals with existing ion-source technology), and designs and tests of high-power target concepts to effectively deal with the full beam power of the driver linac. An NSAC subcommittee recommended the Argonne concept and set as tie design goal Uranium beams of 100-kwatt power at 400 MeV/u. Argonne demonstrated that this goal can be met with an innovative, but technically in-hand, design

  20. Underwater Sound Reference Division

    Data.gov (United States)

    Federal Laboratory Consortium — The Underwater Sound Reference Division (USRD) serves as the U.S. standardizing activity in the area of underwater acoustic measurements, as the National Institute...

  1. Theoretical physics division

    International Nuclear Information System (INIS)

    Research activities of the theoretical physics division for 1979 are described. Short summaries are given of specific research work in the following fields: nuclear structure, nuclear reactions, intermediate energy physics, elementary particles

  2. Highly sensitive micromachined capacitive pressure sensor with reduced hysteresis and low parasitic capacitance

    DEFF Research Database (Denmark)

    Pedersen, Thomas; Fragiacomo, Giulio; Hansen, Ole;

    2009-01-01

    This paper describes the design and fabrication of a capacitive pressure sensor that has a large capacitance signal and a high sensitivity of 76 pF/bar in touch mode operation. Due to the large signal, problems with parasitic capacitances are avoided and hence it is possible to integrate the sens...... bonding to create vacuum cavities. The exposed part of the sensor is perfectly flat such that it can be coated with corrosion resistant thin films. Hysteresis is an inherent problem in touch mode capacitive pressure sensors and a technique to significantly reduce it is presented....

  3. Automatic Power Factor Correction Using Capacitive Bank

    OpenAIRE

    Mr.Anant Kumar Tiwari,; Mrs. Durga Sharma

    2014-01-01

    The power factor correction of electrical loads is a problem common to all industrial companies. Earlier the power factor correction was done by adjusting the capacitive bank manually [1]. The automated power factor corrector (APFC) using capacitive load bank is helpful in providing the power factor correction. Proposed automated project involves measuring the power factor value from the load using microcontroller. The design of this auto-adjustable power factor correction is ...

  4. Enhanced capacitive performance of TiO₂ nanotubes with molybdenum oxide coating

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Dongsheng; Gao, Xianfeng; Li, Jianyang; Yuan, Chris, E-mail: cyuan@uwm.edu

    2014-05-01

    Highlights: • MoO₃ was firstly deposited on TiO₂ nanotubes for better supercapacitive behaviors. • Coated TiO₂ nanotubes showed much higher capacitance than pure TiO₂ or MoO₃ films. • Deposition cycles were optimized to gain the best capacitance of MoO₃/TiO₂ hybrids. - Abstract: Alpha-phase MoO₃ is electrochemically deposited on well-aligned TiO₂ nanotubes which are synthesized by anodic oxidation. The morphology, composition and electrochemical behaviors of MoO₃-coated and bare TiO₂ nanotubes are studied. The former deliver greatly higher capacitance than the latter and their performance can be readily optimized by varying MoO₃ deposition cycles. The large areal capacitance of 209.6 mF cm⁻² at a scan rate of 5 mV s⁻¹ is firstly achieved for TiO₂ nanotube array electrode. In addition, the coated TiO₂ nanotubes show significantly more capacitance than a dense MoO₃ film. For example, they exhibit a capacitance up to 74.9 F g⁻¹ at 5 mV s⁻¹ in 1 M KCl solution, while the dense film only shows a capacitance of 32.3 F g⁻¹ under same conditions. Such improvement is found ascribed to MoO₃ with high pseudocapacity and TiO₂ nanotubes with large surface area allowing efficient MoO₃ nanoparticle loading and rapid charge transfer. This nanostructured electrode with features of facile synthesis and excellent performance is believed as a potential candidate for supercapacitor applications.

  5. Circuital characterisation of space-charge motion with a time-varying applied bias

    OpenAIRE

    Kim, Chul; Moon, Eun-Yi; Hwang, Jungho; Hong, Hiki

    2015-01-01

    Understanding the behaviour of space-charge between two electrodes is important for a number of applications. The Shockley-Ramo theorem and equivalent circuit models are useful for this; however, fundamental questions of the microscopic nature of the space-charge remain, including the meaning of capacitance and its evolution into a bulk property. Here we show that the microscopic details of the space-charge in terms of resistance and capacitance evolve in a parallel topology to give the macro...

  6. Enhanced Capacitance of Hybrid Layered Graphene/Nickel Nanocomposite for Supercapacitors.

    Science.gov (United States)

    Mohd Zaid, Norsaadatul Akmal; Idris, Nurul Hayati

    2016-01-01

    In this work, Ni nanoparticles were directly decorated on graphene (G) nanosheets via mechanical ball milling. Based on transmission electron microscopy observations, the Ni nanoparticles were well dispersed and attached to the G nanosheet without any agglomerations. Electrochemical results showed that the capacitance of a G/Ni nanocomposite was 275 F g(-1) at a current density of 2 A g(-1), which is higher than the capacitance of bare G (145 F g(-1)) and bare Ni (3 F g(-1)). The G/Ni electrode also showed superior performance at a high current density, exhibiting a capacitance of 190 F g(-1) at a current density of 5 A g(-1) and a capacitance of 144 F g(-1) at a current density of 10 A g(-1). The equivalent series resistance for G/Ni nanocomposites also decreased. The enhanced performance of this hybrid supercapacitor is best described by the synergistic effect, i.e. dual charge-storage mechanism, which is demonstrated by electrical double layer and pseudocapacitance materials. Moreover, a high specific surface area and electrical conductivity of the materials enhanced the capacitance. These results indicate that the G/Ni nanocomposite is a potential supercapacitor. PMID:27553290

  7. Capacitance Sensing and Software-Realized Lock-in Amplifier for the Electromagnetically Levitated Micro Gyroscope

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiao-gang; CHEN Wen-yuan; LIU Wu; ZHANG Wei-ping; WU Xiao-sheng

    2007-01-01

    In the novel prototype of micro-gyroscope structure, the new configured capacitance sensing scheme for the micro gyroscope was analyzed and the virtual instrument based detection scheme was implemented. The digital lock-in amplifier was employed in the capacitance detection to restrain the noise interference. The capacitance analysis shows that 1 fF capacitance variation corresponds to 0.1 degree of the turn angle. The differential capacitance bridge and the charge integral amplifier were used as the front signal input interface. In the implementation of digital lock-in amplifier, a new routine which warranted the exactly matching of the reference phase to signal phase was proposed. The result of the experiment shows that digital lock-in amplifier can greatly eliminate the noise in the output signal. The non linearity of the turn angle output is 2.3 % and the minimum resolution of turn angle is 0.04 degrees. The application of the software demodulation in the signal detection of micro-electro-mechanical-system (MEMS) device is a new attempt, and it shows the prospective for a high-performance application.

  8. Enhanced Capacitance of Hybrid Layered Graphene/Nickel Nanocomposite for Supercapacitors

    Science.gov (United States)

    Mohd Zaid, Norsaadatul Akmal; Idris, Nurul Hayati

    2016-08-01

    In this work, Ni nanoparticles were directly decorated on graphene (G) nanosheets via mechanical ball milling. Based on transmission electron microscopy observations, the Ni nanoparticles were well dispersed and attached to the G nanosheet without any agglomerations. Electrochemical results showed that the capacitance of a G/Ni nanocomposite was 275 F g-1 at a current density of 2 A g-1, which is higher than the capacitance of bare G (145 F g-1) and bare Ni (3 F g-1). The G/Ni electrode also showed superior performance at a high current density, exhibiting a capacitance of 190 F g-1 at a current density of 5 A g-1 and a capacitance of 144 F g-1 at a current density of 10 A g-1. The equivalent series resistance for G/Ni nanocomposites also decreased. The enhanced performance of this hybrid supercapacitor is best described by the synergistic effect, i.e. dual charge-storage mechanism, which is demonstrated by electrical double layer and pseudocapacitance materials. Moreover, a high specific surface area and electrical conductivity of the materials enhanced the capacitance. These results indicate that the G/Ni nanocomposite is a potential supercapacitor.

  9. Position sensitive anodes for MCP read-out using induced charge measurement

    Science.gov (United States)

    Jagutzki, O.; Lapington, J. S.; Worth, L. B. C.; Spillman, U.; Mergel, V.; Schmidt-Böcking, H.

    2002-01-01

    We investigate the method of an indirect detection of a MCP charge avalanche projected onto a resistive layer (G. Battistoni, et al., Nucl. Instr. and Meth., 202 (1982) 459). If the sheet resistance is favourable one can detect the charge cloud by the capacitive coupling to an anode structure a few millimetres behind the layer. The anode structure can be, for example, a wedge-and-strip electrode pattern (M. Unverzagt, Diplomarbeit, Universität Frankfurt 1992, private communication) as it is used for directly collecting the electron avalanche from a MCP. Detection of the induced charge is beneficial in several respects. Firstly, image distortions produced by secondary electron mediated charge redistribution are eliminated. Secondly, the noise component due to quantized charge collection, commonly referred to as partition noise, is not present. In addition, the dielectric substrate can function both as an element of the vacuum enclosure and HV insulator, making the electrical connections easily accessible and the pattern operable at ground potential, independently of detector operating voltages. This technique can be used to simplify the electronic design requirements where varying high voltages are required at the detector input face such as plasma analysers, etc. It also has application in the manufacture of intensifier tubes (J. Barnstedt, M. Grewing, Nucl. Instr. and Meth., these proceedings) where the inclusion of a readout pattern inside the intensifier body with associated electrical feed-throughs can prove problematic. We will present data on the performance of such detection geometries using several types of charge division anode, and discuss the advantages compared with the "traditional" charge collecting method.

  10. Capacitance of Graphene Bilayer as a Which-Layer Probe

    OpenAIRE

    Young, Andrea F.; Levitov, Leonid S.

    2011-01-01

    The unique capabilities of capacitance measurements in bilayer graphene enable probing of layer-specific properties that are normally out of reach in transport measurements. Furthermore, capacitance measurements in the top-gate and penetration field geometries are sensitive to different physical quantities: the penetration field capacitance probes the two layers equally, whereas the top gate capacitance preferentially samples the near layer, resulting in the "near-layer capacitance enhancemen...

  11. Peculiarities of capacitive characteristics of dielectrics with high permittivity

    International Nuclear Information System (INIS)

    The rapid pace of development of microelectronics towards nano miniaturization dictates the inevitable introduction of dielectrics with high permittivity (high-k dielectrics), as alternative materials for replacing conventionally used silicon as insulating oxide. Therefore, studying these materials in terms of their characteristics, especially in terms of reliability, is of great importance for proper design and manufacture of devices that incorporate dielectrics with high permittivity. In this paper, different properties and behavior of a group of samples that contain dielectrics with high permittivity are investigated, by analyzing the characteristics of capacitive curves, which are product of this powerful technique for characterization, reflecting a great number of elements for the overall behavior of the material, especially their behavior in working conditions. Samples investigated here belong to the group of tantalum based metal oxides, whereas here we examine layers of pure Ta2O5, but also layers of Hf and Ti doped tantalum pentoxide, i.e. Ta2O5: Hf and Ta2O5: Ti. All samples are considered as ultrathin oxide layers with thicknesses less than 15 nm, and they are obtained by thermal oxidation or by radio frequency sputtering on p-type silicon substrate. From capacitive characteristics we have obtained the specific parameters that determine the properties of materials (capacitance in accumulation, equivalent oxide thickness of dielectric layer, the thickness and time evolution of the interfacial SiO2 layer, characteristic values of flat band and threshold voltage, density of oxide charges present in the layer, as well as interface and border states), and properties that show the behavior of the materials in working conditions (such as the process of creation of additional charges when voltage is applied, or charge trapping dynamics). Particular attention has been paid to determining the impact of the type of top electrode (the gate), on the overall

  12. Charge Qubit-Atom Hybrid

    CERN Document Server

    Yu, Deshui; Hufnagel, C; Kwek, L C; Amico, Luigi; Dumke, R

    2016-01-01

    We investigate a novel hybrid system of a superconducting charge qubit interacting directly with a single neutral atom via electric dipole coupling. Interfacing of the macroscopic superconducting circuit with the microscopic atomic system is accomplished by varying the gate capacitance of the charge qubit. To achieve strong interaction, we employ two Rydberg states with an electric-dipole-allowed transition, which alters the polarizability of the dielectric medium of the gate capacitor. Sweeping the gate voltage with different rates leads to a precise control of hybrid quantum states. Furthermore, we show a possible implementation of a universal two-qubit gate.

  13. Charge-qubit-atom hybrid

    Science.gov (United States)

    Yu, Deshui; Valado, María Martínez; Hufnagel, Christoph; Kwek, Leong Chuan; Amico, Luigi; Dumke, Rainer

    2016-04-01

    We investigate a hybrid system of a superconducting charge qubit interacting directly with a single neutral atom via electric dipole coupling. Interfacing of the macroscopic superconducting circuit with the microscopic atomic system is accomplished by varying the gate capacitance of the charge qubit. To achieve a strong interaction, we employ two Rydberg states with an electric-dipole-allowed transition, which alters the polarizability of the dielectric medium of the gate capacitor. Sweeping the gate voltage with different rates leads to a precise control of hybrid quantum states. Furthermore, we show a possible implementation of a universal two-qubit gate.

  14. Carbon flow electrodes for continuous operation of capacitive deionization and capacitive mixing energy generation

    NARCIS (Netherlands)

    Porada, S.; Hamelers, H.V.M.; Bryjak, M.; Presser, V.; Biesheuvel, P.M.; Weingarth, D.

    2014-01-01

    Capacitive technologies, such as capacitive deionization and energy harvesting based on mixing energy (“capmix” and “CO2 energy”), are characterized by intermittent operation: phases of ion electrosorption from the water are followed by system regeneration. From a system application point of view, c

  15. Enhanced capacitive deionization of graphene/mesoporous carbon composites.

    Science.gov (United States)

    Zhang, Dengsong; Wen, Xiaoru; Shi, Liyi; Yan, Tingting; Zhang, Jianping

    2012-09-01

    Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are well retained and the composites display improved specific surface area and pore size distribution, as well as pore volume. Well dispersed GE nanosheets are deduced to be beneficial for enhanced electrical conductivity. The electrochemical performance of electrodes in an NaCl aqueous solution was characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The composite electrodes perform better on the capacitance values, conductive behaviour, rate performance and cyclic stability. The desalination capacity of the electrodes was evaluated by a batch mode electrosorptive experiment and the amount of adsorbed ions can reach 731 μg g⁻¹ for the GE/MC composite electrode with a GE content of 5 wt%, which is much higher than that of MC alone (590 μg g⁻¹). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area. PMID:22836788

  16. On the hydrophilicity of electrodes for capacitive energy extraction.

    Science.gov (United States)

    Lian, Cheng; Kong, Xian; Liu, Honglai; Wu, Jianzhong

    2016-11-23

    The so-called Capmix technique for energy extraction is based on the cyclic expansion of electrical double layers to harvest dissipative energy arising from the salinity difference between freshwater and seawater. Its optimal performance requires a careful selection of the electrical potentials for the charging and discharging processes, which must be matched with the pore characteristics of the electrode materials. While a number of recent studies have examined the effects of the electrode pore size and geometry on the capacitive energy extraction processes, there is little knowledge on how the surface properties of the electrodes affect the thermodynamic efficiency. In this work, we investigate the Capmix processes using the classical density functional theory for a realistic model of electrolyte solutions. The theoretical predictions allow us to identify optimal operation parameters for capacitive energy extraction with porous electrodes of different surface hydrophobicity. In agreement with recent experiments, we find that the thermodynamic efficiency can be much improved by using most hydrophilic electrodes. PMID:27624786

  17. High capacitance of coarse-grained carbide derived carbon electrodes

    Science.gov (United States)

    Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; Zozulya, Yuliya; Simon, Patrice; Gogotsi, Yury

    2016-02-01

    We report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. Using a titanium carbide (TiC) precursor, we synthesized 70-250 μm sized particles with high surface area and a narrow pore size distribution. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. The material showcased capacitance above 100 F g-1 at sweep rates as high as 250 mV s-1 in organic electrolyte. 250-1000 micron thick dense CDC films with up to 80 mg cm-2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.

  18. Numerical simulation on coupling performance of steam flow field and electric field in capacitance sensor measuring steam wetness

    International Nuclear Information System (INIS)

    Based on the theory of dielectric polarization and hydrodynamics, using the FLUENT UDF code, the coupling performances of the steam flow field and the electric field in the capacitance sensor were numerically simulated. The standard k-ε model, wall function and SIMPLE way were used. The results show that the voltage decreases gradually from positive plate to negative plate, and the change is even; water molecule is polarized, the polarized charge appears near the plates, and there is no polarized charge in the center of sensor when the dry saturation steam flows through the capacitance sensor; the radial velocity is different from with and without electric field in the capacitance sensor, and the difference is max near the outmost plate; the electric field near the plate is smaller when there is no flow field. The results of numerical simulation match with the results of experiment. The numerical simulation model is feasibility. (authors)

  19. Theoretical Division progress report

    International Nuclear Information System (INIS)

    This report presents highlights of activities in the Theoretical (T) Division from October 1976-January 1979. The report is divided into three parts. Part I presents an overview of the Division: its unique function at the Los Alamos Scientific Laboratory (LASL) and within the scientific community as a whole; the organization of personnel; the main areas of research; and a survey of recent T-Division initiatives. This overview is followed by a survey of the 13 groups within the Division, their main responsibilities, interests, and expertise, consulting activities, and recent scientific accomplisments. The remainder of the report, Parts II and III, is devoted to articles on selected research activities. Recent efforts on topics of immediate interest to energy and weapons programs at LASL and elsewhere are described in Part II, Major National Programs. Separate articles present T-Divison contributions to weapons research, reactor safety and reactor physics research, fusion research, laser isotope separation, and other energy research. Each article is a compilation of independent projects within T Division, all related to but addressing different aspects of the major program. Part III is organized by subject discipline, and describes recent scientific advances of fundamental interest. An introduction, defining the scope and general nature of T-Division efforts within a given discipline, is followed by articles on the research topics selected. The reporting is done by the scientists involved in the research, and an attempt is made to communicate to a general audience. Some data are given incidentally; more technical presentations of the research accomplished may be found among the 47 pages of references. 110 figures, 5 tables

  20. Preconditioning first and second kind integral formulations of the capacitance problem

    Energy Technology Data Exchange (ETDEWEB)

    Tausch, J.; White, J.

    1996-12-31

    Engineering programs which compute electrostatic capacitances for complicated arrangements of conductors commonly set up the electrostatic potential u as a superposition of surface carges {sigma} u(x) = {integral}{sub s}G(x, y){sigma}(y) dS(y). Where G(x, y) = {1/4}{pi}{vert_bar}x - y{vert_bar} is the Green`s function for the Laplacian in the three-space. For a specified potential on the conductor surface(s) S, this approach leads to an integral equation of the first kind on S for the charge density {sigma}. The capacitance is the net-charge on the conductors and is given by the surface integral of {sigma}.

  1. Anomalous increase in carbon capacitance at pore sizes less than 1 nanometer.

    Science.gov (United States)

    Chmiola, J; Yushin, G; Gogotsi, Y; Portet, C; Simon, P; Taberna, P L

    2006-09-22

    Carbon supercapacitors, which are energy storage devices that use ion adsorption on the surface of highly porous materials to store charge, have numerous advantages over other power-source technologies, but could realize further gains if their electrodes were properly optimized. Studying the effect of the pore size on capacitance could potentially improve performance by maximizing the electrode surface area accessible to electrolyte ions, but until recently, no studies had addressed the lower size limit of accessible pores. Using carbide-derived carbon, we generated pores with average sizes from 0.6 to 2.25 nanometer and studied double-layer capacitance in an organic electrolyte. The results challenge the long-held axiom that pores smaller than the size of solvated electrolyte ions are incapable of contributing to charge storage.

  2. Nanocellulose coupled flexible polypyrrole@graphene oxide composite paper electrodes with high volumetric capacitance

    Science.gov (United States)

    Wang, Zhaohui; Tammela, Petter; Strømme, Maria; Nyholm, Leif

    2015-02-01

    A robust and compact freestanding conducting polymer-based electrode material based on nanocellulose coupled polypyrrole@graphene oxide paper is straightforwardly prepared via in situ polymerization for use in high-performance paper-based charge storage devices, exhibiting stable cycling over 16 000 cycles at 5 A g-1 as well as the largest specific volumetric capacitance (198 F cm-3) so far reported for flexible polymer-based electrodes.A robust and compact freestanding conducting polymer-based electrode material based on nanocellulose coupled polypyrrole@graphene oxide paper is straightforwardly prepared via in situ polymerization for use in high-performance paper-based charge storage devices, exhibiting stable cycling over 16 000 cycles at 5 A g-1 as well as the largest specific volumetric capacitance (198 F cm-3) so far reported for flexible polymer-based electrodes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07251k

  3. 07261 Summary -- Fair Division

    OpenAIRE

    Brams, Steven J.; Pruhs, Kirk

    2007-01-01

    The problem of fair division—dividing goods or "bads" (e.g., costs) among entities in an impartial and equitable way—is one of the most important problems that society faces. A Google search on the phrase "fair allocation" returns over 100K links, referring to the division of sports tickets, health resources, computer networking resources, voting power, intellectual property licenses, costs of environmental improvements, etc.

  4. Ion channels, phosphorylation and mammalian sperm capacitation.

    Science.gov (United States)

    Visconti, Pablo E; Krapf, Dario; de la Vega-Beltrán, José Luis; Acevedo, Juan José; Darszon, Alberto

    2011-05-01

    Sexually reproducing animals require an orchestrated communication between spermatozoa and the egg to generate a new individual. Capacitation, a maturational complex phenomenon that occurs in the female reproductive tract, renders spermatozoa capable of binding and fusing with the oocyte, and it is a requirement for mammalian fertilization. Capacitation encompasses plasma membrane reorganization, ion permeability regulation, cholesterol loss and changes in the phosphorylation state of many proteins. Novel tools to study sperm ion channels, image intracellular ionic changes and proteins with better spatial and temporal resolution, are unraveling how modifications in sperm ion transport and phosphorylation states lead to capacitation. Recent evidence indicates that two parallel pathways regulate phosphorylation events leading to capacitation, one of them requiring activation of protein kinase A and the second one involving inactivation of ser/thr phosphatases. This review examines the involvement of ion transporters and phosphorylation signaling processes needed for spermatozoa to achieve capacitation. Understanding the molecular mechanisms leading to fertilization is central for societies to deal with rising male infertility rates, to develop safe male gamete-based contraceptives and to preserve biodiversity through better assisted fertilization strategies.

  5. Ion channels, phosphorylation and mammalian sperm capacitation

    Institute of Scientific and Technical Information of China (English)

    Pablo E Visconti; Dario Krapf; José Luis de la Vega-Beltrán; Juan José Acevedo; Alberto Darszon

    2011-01-01

    Sexually reproducing animals require an orchestrated communication between spermatozoa and the egg to generate a new individual. Capacitation, a maturational complex phenomenon that occurs in the female reproductive tract, renders spermatozoa capable of binding and fusing with the oocyte, and it is a requirement for mammalian fertilization. Capacitation encompasses plasma membrane reorganization, ion permeability regulation, cholesterol loss and changes in the phosphorylation state of many proteins. Novel tools to study sperm ion channels, image intracellular ionic changes and proteins with better spatial and temporal resolution, are unraveling how modifications in sperm ion transport and phosphorylation states lead to capacitation. Recent evidence indicates that two parallel pathways regulate phosphorylation events leading to capacitation, one of them requiring activation of protein kinase A and the second one involving inactivation of ser/thr phosphatases. This review examines the involvement of ion transporters and phosphorylation signaling processes needed for spermatozoa to achieve capacitation. Understanding the molecular mechanisms leading to fertilization is central for societies to deal with rising male infertility rates, to develop safe male gamete-based contraceptives and to preserve biodiversity through better assisted fertilization strategies.

  6. Enhanced capacitive deionization performance of graphene by nitrogen doping.

    Science.gov (United States)

    Xu, Xingtao; Pan, Likun; Liu, Yong; Lu, Ting; Sun, Zhuo

    2015-05-01

    Nitrogen-doped graphene (NG) was fabricated via a simple thermal treatment of graphene oxide in an ammonia atmosphere. The morphology, structure and electrochemical performance of NG were characterized by scanning electron microscopy, Raman spectroscopy, nitrogen adsorption-desorption, X-ray photoelectron spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The electrosorption performance of NG in NaCl solution was studied and compared with pristine graphene (PG). The results show that due to its high specific surface area, increased specific capacitance and low charge transfer resistance, NG exhibits high electrosorption capacity of 4.81 mg g(-1) when the initial solution conductivity is 100 μS cm(-1), which are much higher than those of PG (3.85 mg g(-1)). PMID:25617614

  7. Characterization of active CMOS sensors for capacitively coupled pixel detectors

    Energy Technology Data Exchange (ETDEWEB)

    Hirono, Toko; Gonella, Laura; Janssen, Jens; Hemperek, Tomasz; Huegging, Fabian; Krueger, Hans; Wermes, Norbert [Institute of Physics, University of Bonn (Germany); Peric, Ivan [Institut fuer Prozessdatenverarbeitung und Elektronik, Karlsruher Institut fuer Technologie, Karlsruhe (Germany)

    2015-07-01

    Active CMOS pixel sensor is one of the most attractive candidates for detectors of upcoming particle physics experiments. In contrast to conventional sensors of hybrid detectors, signal processing circuit can be integrated in the active CMOS sensor. The characterization and optimization of the pixel circuit are indispensable to obtain a good performance from the sensors. The prototype chips of the active CMOS sensor were fabricated in the AMS 180nm and L-Foundry 150 nm CMOS processes, respectively a high voltage and high resistivity technology. Both chips have a charge sensitive amplifier and a comparator in each pixel. The chips are designed to be glued to the FEI4 pixel readout chip. The signals from 3 pixels of the prototype chips are capacitively coupled to the FEI4 input pads. We have performed lab tests and test beams to characterize the prototypes. In this presentation, the measurement results of the active CMOS prototype sensors are shown.

  8. Capacitively coupled hybrid pixel assemblies for the CLIC vertex detector

    CERN Document Server

    Alipour Tehrani, Niloufar; Benoit, Mathieu; Dannheim, Dominik; Dette, Karola; Hynds, Daniel; Kulis, Szymon; Peric, Ivan; Petric, Marko; Redford, Sophie; Sicking, Eva; Valerio, Pierpaolo

    2015-01-01

    The vertex detector at the proposed CLIC multi-TeV linear e+e- collider must have minimal material content and high spatial resolution, combined with accurate time-stamping to cope with the expected high rate of beam-induced backgrounds. One of the options being considered is the use of active sensors implemented in a commercial high-voltage CMOS process, capacitively coupled to hybrid pixel ASICs. A prototype of such an assembly, using two custom designed chips (CCPDv3 as active sensor glued to a CLICpix readout chip), has been characterised both in the lab and in beam tests at the CERN SPS using 120 GeV/c positively charged hadrons. Results of these characterisation studies are presented both for single and dual amplification stages in the active sensor. Pixel cross-coupling results are also presented, showing the sensitivity to placement precision and planarity of the glue layer.

  9. Effect of substituent position on electrodeposition, morphology, and capacitance performance of polyindole bearing a carboxylic group

    International Nuclear Information System (INIS)

    Graphical abstract: The effect of carboxylic substituent position on the electrodeposition, morphology, and capacitance performance of substituted polyindole derivative nanowires were investigated for the first time. The results indicated that the position of the carboxylic substitution had remarkable impact on the diameter size and capacitance performance of these polymer nanowires. Furthermore, these polymers with high specific capacitance and excellent stability would be strong candidates as electrode material for supercapacitor. - Highlights: • Three carboxylic group substituted polyindole nanowires were synthesized. • Effect of substituent position on their morphology was firstly reported. • Effect of substituent position on their capacitance performance was reported. • The three polyindole nanowires showed excellent capacitance performance. - Abstract: In this paper, the effects of carboxylic substituent position on their electrodeposition, morphology and capacitance properties were investigated for the first time. The results indicated that three carboxylic group substituted polyindole derivatives nanowires, namely poly(indole-5-carboxylic acid) (5-PICA), poly(indole-6-carboxylic acid) (6-PICA), and poly(indole-7-carboxylic acid) (7-PICA), were successfully electrochemically synthesized in acetonitrile containing 0.1 M LiClO4, whereas poly(indole-4-carboxylic acid) (4-PICA) was difficult to be obtained. For 5-PICA, 6-PICA and 7-PICA nanowires, the diameters of nanowires demonstrated by the scanning electron microscopy were about 100 nm, 50 nm, and 30 nm, respectively. Their specific capacitances and energy densities in 1.0 M H2SO4 solution were measured to be 355 F g−1, 383 F g−1, 430 F g−1 at 2.5 A g−1 and 40.0, 43.1, 48.3 Wh kg−1 at a power density of 1125 W kg−1, respectively, and their specific capacitance retentions after 1000 charge/discharge processes reached 94.5%, 95.1%, and 96%, respectively. These results indicated that the

  10. Capacitive Deionization using Biomass-based Microporous Salt-Templated Heteroatom-Doped Carbons.

    Science.gov (United States)

    Porada, Slawomir; Schipper, Florian; Aslan, Mesut; Antonietti, Markus; Presser, Volker; Fellinger, Tim-Patrick

    2015-06-01

    Invited for this month's cover are the groups of Tim-Patrick Fellinger (MPI Potsdam) and Volker Presser (INM Saarbrücken and Saarland University). The image shows the dynamic process of ion electrosorption: anions are attracted and cations repelled from electrically charged electrodes based on carbons with heteroatoms. This process of capacitive deionization is particularly attractive for facile low-energy water treatment applications. PMID:26039519

  11. Metal-organic framework-derived porous carbon polyhedra for highly efficient capacitive deionization.

    Science.gov (United States)

    Liu, Yong; Xu, Xingtao; Wang, Miao; Lu, Ting; Sun, Zhuo; Pan, Likun

    2015-08-01

    Porous carbon polyhedra (PCP) were prepared through direct carbonization of zeolitic imidazolate framework-8 and used as an electrode material for capacitive deionization. The results show that PCP treated at 1200 °C exhibit the highest electrosorption capacity of 13.86 mg g(-1) when the initial NaCl concentration is 500 mg l(-1), due to their high accessible surface area and low charge transfer resistance. PMID:26121467

  12. Design of a High Voltage Bidirectional DC-DC Converter for Driving Capacitive Incremental Actuators usable in Electric Vehicles (EVs)

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.;

    2014-01-01

    and medical industries. The design of the bidirectional flyback converter to charge and discharge a 400 nF capacitive actuator is presented, when 4 kV and 4.5 kV high voltage MOSFETs are used on the secondary high voltage side. The experimental results and efficiency measurements of the converter...

  13. Carbon nanofiber supercapacitors with large areal capacitances

    KAUST Repository

    McDonough, James R.

    2009-01-01

    We develop supercapacitor (SC) devices with large per-area capacitances by utilizing three-dimensional (3D) porous substrates. Carbon nanofibers (CNFs) functioning as active SC electrodes are grown on 3D nickel foam. The 3D porous substrates facilitate a mass loading of active electrodes and per-area capacitance as large as 60 mg/ cm2 and 1.2 F/ cm2, respectively. We optimize SC performance by developing an annealing-free CNF growth process that minimizes undesirable nickel carbide formation. Superior per-area capacitances described here suggest that 3D porous substrates are useful in various energy storage devices in which per-area performance is critical. © 2009 American Institute of Physics.

  14. A high performance, variable capacitance accelerometer

    Science.gov (United States)

    Wilner, L. Bruce

    1988-12-01

    A variable capacitance acceleration sensor is described. Manufactured using silicon microfabrication techniques, the sensor uses a midplane, flat plate suspension, gas damping, and overrange stops. The sensor is assembled from three silicon wafers, using anodic bonds to inlays of borosilicate glass. Typical sensor properties are 7-pF active capacitance, 3-pF tare capacitance, a response of 0.05 pF/G, a resonance frequency of 3.4 kHz, and damping 0.7 critical. It is concluded that this sensor, with appropriate electronics, forms an accelerometer with an order-of-magnitude greater sensitivity-bandwidth product than a comparable piezoresistive acclerometer, and with extraordinary shock resistance.

  15. Microphonics in biopotential measurements with capacitive electrodes.

    Science.gov (United States)

    Luna-Lozano, Pablo S; Pallas-Areny, Ramon

    2010-01-01

    Biopotential measurements with capacitive electrodes do not need any direct contact between electrode and skin, which saves the time devoted to expose and prepare the contact area when measuring with conductive electrodes. However, mechanical vibrations resulting from physiological functions such as respiration and cardiac contraction can change the capacitance of the electrode and affect the recordings. This transformation of mechanical vibrations into undesired electric signals is termed microphonics. We have evaluated microphonics in capacitive ECG recordings obtained from a dressed subject seated on a common chair with electrodes placed on the front side of the backrest of the chair. Depending on the softness of the backrest, the recordings may be clearly affected by the displacement of the thorax back wall due to the respiration and to the heart's mechanical activity.

  16. Water desalination using capacitive deionization with microporous carbon electrodes.

    Science.gov (United States)

    Porada, S; Weinstein, L; Dash, R; van der Wal, A; Bryjak, M; Gogotsi, Y; Biesheuvel, P M

    2012-03-01

    Capacitive deionization (CDI) is a water desalination technology in which salt ions are removed from brackish water by flowing through a spacer channel with porous electrodes on each side. Upon applying a voltage difference between the two electrodes, cations move to and are accumulated in electrostatic double layers inside the negatively charged cathode and the anions are removed by the positively charged anode. One of the key parameters for commercial realization of CDI is the salt adsorption capacity of the electrodes. State-of-the-art electrode materials are based on porous activated carbon particles or carbon aerogels. Here we report the use for CDI of carbide-derived carbon (CDC), a porous material with well-defined and tunable pore sizes in the sub-nanometer range. When comparing electrodes made with CDC with electrodes based on activated carbon, we find a significantly higher salt adsorption capacity in the relevant cell voltage window of 1.2-1.4 V. The measured adsorption capacity for four materials tested negatively correlates with known metrics for pore structure of the carbon powders such as total pore volume and BET-area, but is positively correlated with the volume of pores of sizes <1 nm, suggesting the relevance of these sub-nanometer pores for ion adsorption. The charge efficiency, being the ratio of equilibrium salt adsorption over charge, does not depend much on the type of material, indicating that materials that have been identified for high charge storage capacity can also be highly suitable for CDI. This work shows the potential of materials with well-defined sub-nanometer pore sizes for energy-efficient water desalination. PMID:22329838

  17. | Division of Cancer Prevention

    Science.gov (United States)

    The Division of Cancer Prevention (DCP) conducts and supports research to determine a person's risk of cancer and to find ways to reduce the risk. This knowledge is critical to making progress against cancer because risk varies over the lifespan as genetic and epigenetic changes can transform healthy tissue into invasive cancer.

  18. Encrypted integer division

    NARCIS (Netherlands)

    Veugen, P.J.M.

    2010-01-01

    When processing signals in the encrypted domain, homomorphic encryption can be used to enable linear operations on encrypted data. Integer division of encrypted data however requires an additional protocol with the server and will be relatively expensive. We present new solutions for dividing encryp

  19. The Problem with Division

    Science.gov (United States)

    Pope, Sue

    2012-01-01

    Of the "big four", division is likely to regarded by many learners as "the odd one out", "the difficult one", "the one that is complicated", or "the scary one". It seems to have been that way "for ever", in the perception of many who have trodden the learning pathways through the world of number. But, does it have to be like this? Clearly the…

  20. Talking Division Up

    DEFF Research Database (Denmark)

    Villadsen, Lisa Storm

    introducing concerns of division that were at odds with daily life in the region. I argue that it was driven by motives that were somewhat extraneous to the cause of language priority, based as they were on concerns of expediency with regard to the most effective way to escape the power monopoly...

  1. Solid State Division

    International Nuclear Information System (INIS)

    This report contains brief discussions on work done in the Solid State Division of Oak Ridge National Laboratory. The topics covered are: Theoretical Solid State Physics; Neutron scattering; Physical properties of materials; The synthesis and characterization of materials; Ion beam and laser processing; and Structure of solids and surfaces

  2. Solid State Division

    Energy Technology Data Exchange (ETDEWEB)

    Green, P.H.; Watson, D.M. (eds.)

    1989-08-01

    This report contains brief discussions on work done in the Solid State Division of Oak Ridge National Laboratory. The topics covered are: Theoretical Solid State Physics; Neutron scattering; Physical properties of materials; The synthesis and characterization of materials; Ion beam and laser processing; and Structure of solids and surfaces. (LSP)

  3. Microwave-Assisted Synthesis of Highly-Crumpled, Few-Layered Graphene and Nitrogen-Doped Graphene for Use as High-Performance Electrodes in Capacitive Deionization

    OpenAIRE

    Ahmad Amiri; Goodarz Ahmadi; Mehdi Shanbedi; Maryam Savari; Kazi, S. N.; B. T. Chew

    2015-01-01

    Capacitive deionization (CDI) is a promising procedure for removing various charged ionic species from brackish water. The performance of graphene-based material in capacitive deionization is lower than the expectation of the industry, so highly-crumpled, few-layered graphene (HCG) and highly-crumpled nitrogen-doped graphene (HCNDG) with high surface area have been introduced as promising candidates for CDI electrodes. Thus, HCG and HCNDG were prepared by exfoliation of graphite in the presen...

  4. Novel graphene-like electrodes for capacitive deionization.

    Science.gov (United States)

    Li, Haibo; Zou, Linda; Pan, Likun; Sun, Zhuo

    2010-11-15

    Capacitive deionization (CDI) is a novel technology that has been developed for removal of charged ionic species from salty water, such as salt ions. The basic concept of CDI, as well as electrosorption, is to force charged ions toward oppositely polarized electrodes through imposing a direct electric field to form a strong electrical double layer and hold the ions. Once the electric field disappears, the ions are instantly released back to the bulk solution. CDI is an alternative low-energy consumption desalination technology. Graphene-like nanoflakes (GNFs) with relatively high specific surface area have been prepared and used as electrodes for capacitive deionization. The GNFs were synthesized by a modified Hummers' method using hydrazine for reduction. They were characterized by atomic force microscopy, N2 adsorption at 77 K and electrochemical workstation. It was found that the ratio of nitric acid and sulfuric acid plays a vital role in determining the specific surface area of GNFs. Its electrosorption performance was much better than commercial activated carbon (AC), suggesting a great potential in capacitive deionisation application. Further, the electrosorptive performance of GNFs electrodes with different bias potentials, flow rates and ionic strengths were measured and the electrosorption isotherm and kinetics were investigated. The results showed that GNFs prepared by this process had the specific surface area of 222.01 m²/g. The specific electrosorptive capacity of the GNFs was 23.18 µmol/g for sodium ions (Na+) when the initial concentration was at 25 mg/L, which was higher than that of previously reported data using graphene and AC under the same experimental condition. In addition, the equilibrium electrosorption capacity was determined as 73.47 µmol/g at 2.0 V by fitting data through the Langmuir isotherm, and the rate constant was found to be 1.01 min⁻¹ by fitting data through pseudo first-order adsorption. The results suggested that the

  5. The pyramidal capacitated vehicle routing problem

    DEFF Research Database (Denmark)

    Lysgaard, Jens

    2010-01-01

    This paper introduces the pyramidal capacitated vehicle routing problem (PCVRP) as a restricted version of the capacitated vehicle routing problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the pyramidal traveling salesman problem (PTSP). A pyramidal....... A main feature of the algorithm is that exact pricing over elementary routes are done in pseudo-polynomial time. Computational results suggest that PCVRP solutions are highly useful for obtaining near-optimal solutions to the CVRP. Furthermore, pricing of pyramidal routes may prove to be very useful...

  6. Experimental study of negative capacitance in LEDs

    Institute of Scientific and Technical Information of China (English)

    FENG Lie-feng; WANG Jun; ZHU Chuan-yun; CONG Hong-xia; CHEN Yong; WANG Cun-da

    2005-01-01

    The experimental study on negative capacitance(NC) of various light-emitting diodes(LEDs) is presented.Experimental result shows that all LEDs display the NC phenomenon.The voltage modulated electroluminescence(VMEL) experiment confirms that the reason of negative capacitance is the strong recombination of the injected carriers in the active region of luminescence.The measures also verify that the dependence of NC on voltage and frequency in different LEDs is similar: NC phenomenon is more obvious with higher voltage or lower frequency.

  7. Design and simulation of MEMS capacitive magnetometer

    Science.gov (United States)

    Jyoti, Aditi, Tripathi, C. C.; Gopal, Ram

    2016-04-01

    This paper presents the design and simulation of a MEMS Capacitive Magnetometer using FEM (Finite Element Method) tool COMSOL Multiphysics 4.3b and results from this simulation are closely matched with analytically calculated results. A comb drive structure is used for actuation purpose which operates at resonant frequency of device is 11.791 kHz to achieve maximum displacement. A magnetic field in z-axis can be detected by this comb drive structure. Quality factor of MEMS capacitive magnetometer obtained is 18 and it has good linear response in the magnetic field range of 100 µT.

  8. Effect of Additive Agent on the Electrochemical Capacitance of Activated Carbon

    Institute of Scientific and Technical Information of China (English)

    Wang Gui-Xin; Qu Mei-Zhen; Chen Li; Wang Guo-Ping; Zhang Qing-Tang; Yu Zuo-Long

    2004-01-01

    In order to compare the effect of additive agent on the electrochemical capacitance of activated carbon, three additive agents like carbon nanotubes (CNTs), activated carbon fibre (ACF)and acetylene black (AB) were added to activated carbon by ultrasonic dispersion. Two electrodes including 95wt.% activated carbon, 2wt.% additive agent and 3wt.% PTFE binder were prepared.Ecs were assembled in an argon-filled glove box by sandwiching a microporous separator (Celgard 2400) between two electrodes. 1.0 M LiClO4/ethylene carbonate (EC)-diethyl carbonate (DEC) (1:1in vol.) was used as the electrolyte. The performance of the Ecs was tested with constant current charge-discharge model between 0.0 and 3.0V at 298K using a battery-testing instrument under the same conditions.From the Fig. 1, we can know that the specific capacitance decreases with the current density increasing. As far as the three carbon materials, CNTs show better performance than others. At low current density, the specific capacitance of CNTs is adjacent to that of ACF, while higher than that of AB; At high current density, the specific capacitance of CNTs is higher than that of both ACF and AB. What's more, capacity fading of CNTs is smaller than those of both ACF and AB. At 10 mA/cm2 current density, the specific capacitance of CNTs is 1.33 times of that ACF and 1.58 times of that AB, respectively. From the CVs (Fig. 2), the capacitance of three materials is contributed mainly by double-layer, nonfaradically. The performance difference is ascribed to the structure and electrolyte reservoir: CNTs used have a wide diameter range between 20 and 100nm and hollow tube structure, ACF has a narrow diameter range and many micropores, AB are dots and cannot form good conductive net. All the above reasons lead the different electrochemical properties of three additive agents.

  9. Isolating the effect of pore size distribution on electrochemical double-layer capacitance using activated fluid coke

    Science.gov (United States)

    Zuliani, Jocelyn E.; Tong, Shitang; Kirk, Donald W.; Jia, Charles Q.

    2015-12-01

    Electrochemical double-layer capacitors (EDLCs) use physical ion adsorption in the capacitive electrical double layer of high specific surface area (SSA) materials to store electrical energy. Previous work shows that the SSA-normalized capacitance increases when pore diameters are less than 1 nm. However, there still remains uncertainty about the charge storage mechanism since the enhanced SSA-normalized capacitance is not observed in all microporous materials. In previous studies, the total specific surface area and the chemical composition of the electrode materials were not controlled. The current work is the first reported study that systematically compares the performance of activated carbon prepared from the same raw material, with similar chemical composition and specific surface area, but different pore size distributions. Preparing samples with similar SSAs, but different pores sizes is not straightforward since increasing pore diameters results in decreasing the SSA. This study observes that the microporous activated carbon has a higher SSA-normalized capacitance, 14.1 μF cm-2, compared to the mesoporous material, 12.4 μF cm-2. However, this enhanced SSA-normalized capacitance is only observed above a threshold operating voltage. Therefore, it can be concluded that a minimum applied voltage is required to induce ion adsorption in these sub-nanometer micropores, which increases the capacitance.

  10. Facile preparation of polypyrrole/graphene oxide nanocomposites with large areal capacitance using electrochemical codeposition for supercapacitors

    Science.gov (United States)

    Zhou, Haihan; Han, Gaoyi; Xiao, Yaoming; Chang, Yunzhen; Zhai, Hua-Jin

    2014-10-01

    A simple and low-cost electrochemical codeposition method has been introduced to fabricate polypyrrole/graphene oxide (PPy/GO) nanocomposites and the areal capacitance of conducting polymer/GO composites is reported for the first time. Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) are implemented to determine the PPy/GO nanocomposites are successfully prepared and the interaction between PPy and GO. The as-prepared PPy/GO nanocomposites show the curly sheet-like morphology, superior capacitive behaviors and cyclic stability. Furthermore, the varying deposition time is implemented to investigate the impact of the loading amount on electrochemical behavior of the composites, and a high areal capacitance of 152 mF cm-2 is achieved at 10 mV s-1 CV scan. However, the thicker films caused by the long deposition time would result in larger diffusion resistance of electrolyte ions, consequently exhibit the relatively lower capacitance value at the high current density. The GCD tests indicate moderate deposition time is more suitable for the fast charge/discharge. Considering the very simple and effective synthetic process, the PPy/GO nanocomposites with relatively high areal capacitance are competitive candidate for supercapacitor application, and its capacitive performances can be easily tuned by varying the deposition time.

  11. Identification of the transient stress-induced leakage current in silicon dioxide films for use in microelectromechanical systems capacitive switches

    Science.gov (United States)

    Ryan, C.; Olszewski, Z.; Houlihan, R.; O'Mahony, C.; Blake, A.; Duane, R.

    2015-04-01

    Dielectric charging at low electric fields is characterized on radio-frequency microelectromechanical systems (RF MEMS) capacitive switches. The dielectric under investigation is silicon dioxide deposited by plasma enhanced chemical vapor deposition. The switch membrane is fabricated using a metal alloy which is shown to be mechanically robust. In the absence of mechanical degradation, these capacitive switches are appropriate test structures for the study of dielectric charging in MEMS devices. Monitoring the shift and recovery of device capacitance-voltage characteristics revealed the presence of a charging mechanism which takes place across the bottom metal-dielectric interface. Current measurements on metal-insulator-metal devices confirmed the presence of interfacial charging and discharging transient currents. The field- and temperature-dependence of these currents is the same as the well-known transient stress-induced leakage current (SILC) observed in flash memory devices. A simple model was created based on established transient SILC theory which accurately fits the measured data and reveals that charge exchange at the bottom metal-dielectric interface is responsible for charging currents and pull-in voltage changes in these MEMS devices.

  12. An electrostatic model for biological cell division

    CERN Document Server

    Faraggi, Eshel

    2010-01-01

    Probably the most fundamental processes for biological systems is their ability to create themselves through the use of cell division and cell differentiation. In this work a simple physical model is proposed for biological cell division. The model consists of a positive ionic gradient across the cell membrane, and concentration of charge at the nodes of the spindle and on the chromosomes. A simple calculation, based on Coulomb's Law, shows that under such circumstances a chromosome will tend to break up to its constituent chromatids and that the chromatids will be separated by a distance that is an order of thirty percent of the distance between the spindle nodes. Further repulsion between the nodes will tend to stretch the cell and eventually break the cell membrane between the separated chromatids, leading to cell division. The importance of this work is in continuing the understanding of the electromagnetic basis of cell division and providing it with an analytical model. A central implication of this and...

  13. Development of a 3D capacitive gyroscope with reduced parasitic capacitance

    International Nuclear Information System (INIS)

    We present the development of a technological platform dedicated to 3D capacitive inertial sensors. The proof of concept will be made on a 3D gyroscope. The mobile structure is made within a 30 µm thick Si top layer of a SOI substrate, while poly-Si deposited on top of a sacrificial PSG layer serves as suspended top electrodes and connection wires. This technology enables us to maintain low parasitic capacitance, which is of paramount significance for capacitive detection. After packaging and association with an analogue electronic board, functionality of the sensor is demonstrated. (paper)

  14. Quantum Fluctuations of Mesoscopic Damped Circuit Involving Capacitance-Inductance Coupling at a Finite Temperature

    Science.gov (United States)

    Xu, Xing-Lei; Xu, Shi-Min; Li, Hong-Qi

    2008-06-01

    The quantization of mesoscopic damped circuit involving capacitance-inductance coupling is proposed by the method of thrice linear transformation and damped harmonic oscillator quantization. The quantum fluctuations of the charges and current of each loop are calculated by thermo-field dynamics (TFD) in thermal vacuum state, thermal coherent state and thermal squeezed state, respectively. It is shown that the quantum fluctuations of the charges and current not only depend on circuit inherent parameter and coupled magnitude, but also rely on squeezed coefficients, squeezed angle, environmental temperature and damped resistance. And, because of influence of environmental temperature and damped resistance, the quantum fluctuations increase with increasing temperature and decrease with prolonging time.

  15. Enhanced capacitive deionization of graphene/mesoporous carbon composites

    Science.gov (United States)

    Zhang, Dengsong; Wen, Xiaoru; Shi, Liyi; Yan, Tingting; Zhang, Jianping

    2012-08-01

    Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are well retained and the composites display improved specific surface area and pore size distribution, as well as pore volume. Well dispersed GE nanosheets are deduced to be beneficial for enhanced electrical conductivity. The electrochemical performance of electrodes in an NaCl aqueous solution was characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The composite electrodes perform better on the capacitance values, conductive behaviour, rate performance and cyclic stability. The desalination capacity of the electrodes was evaluated by a batch mode electrosorptive experiment and the amount of adsorbed ions can reach 731 μg g-1 for the GE/MC composite electrode with a GE content of 5 wt%, which is much higher than that of MC alone (590 μg g-1). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area.Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are

  16. Quantum capacitance of the armchair-edge graphene nanoribbon

    Indian Academy of Sciences (India)

    Ling-Feng Mao

    2013-08-01

    The quantum capacitance, an important parameter in the design of nanoscale devices, is derived for armchair-edge single-layer graphene nanoribbon with semiconducting property. The quantum capacitance oscillations are found and these capacitance oscillations originate from the lateral quantum confinement in graphene nanoribbon. Detailed studies of the capacitance oscillations demonstrate that the local channel electrostatic potential at the capacitance peak, the height and the number of the capacitance peak strongly depend on the width, especially a few nanometres, of the armchair-edge graphene nanoribbon. It implies that the capacitance oscillations observed in the experiments can be utilized to measure the width of graphene nanoribbon. The results also show that the capacitance oscillations are not seen when the width is larger than 30 nm.

  17. Analysis of mutual capacitance and inductance of printed circuit

    OpenAIRE

    Ivanov, V. G.

    2014-01-01

    The article analyzes the mutual capacitance and inductance of printed circuit and introduces an evaluation technique for conductor-to-conductor capacitance under electrical connections tracing, the technique based on a multi-layer channel model.

  18. Observation of Quantum Capacitance of individual single walled carbon nanotubes

    OpenAIRE

    Dai, Junfeng; Li, Jun; Zeng, Hualing; Cui, Xiaodong

    2008-01-01

    We report a measurement on quantum capacitance of individual semiconducting and small band gap SWNTs. The observed quantum capacitance is remarkably smaller than that originating from density of states and it implies a strong electron correlation in SWNTs.

  19. 75 FR 16178 - Antitrust Division

    Science.gov (United States)

    2010-03-31

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Antitrust Division Notice Pursuant to the National Cooperative Research and Production Act of 1993--Joint... Director of Operations, Antitrust Division. BILLING CODE 4410-11-M...

  20. 77 FR 38831 - Antitrust Division

    Science.gov (United States)

    2012-06-29

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Antitrust Division Notice Pursuant to the National Cooperative Research and Production Act of 1993... Civil Enforcement, Antitrust Division. BILLING CODE P...

  1. Thermodynamic cycle analysis for capacitive deionization

    NARCIS (Netherlands)

    Biesheuvel, P.M.

    2009-01-01

    Capacitive deionization (CDI) is an ion removal technology based on temporarily storing ions in the polarization layers of two oppositely positioned electrodes. Here we present a thermodynamic model for the minimum work required for ion separation in the fully reversible case by describing the ionic

  2. Capacitive Proximity Sensors With Additional Driven Shields

    Science.gov (United States)

    Mcconnell, Robert L.

    1993-01-01

    Improved capacitive proximity sensors constructed by incorporating one or more additional driven shield(s). Sensitivity and range of sensor altered by adjusting driving signal(s) applied to shield(s). Includes sensing electrode and driven isolating shield that correspond to sensing electrode and driven shield.

  3. Phase-Discriminating Capacitive Sensor System

    Science.gov (United States)

    Vranish, John M.; Rahim, Wadi

    1993-01-01

    Crosstalk eliminated by maintaining voltages on all electrodes at same amplitude, phase, and frequency. Each output feedback-derived control voltage, change of which indicates proximity-induced change in capacitance of associated sensing electrode. Sensors placed close together, enabling imaging of sort. Images and/or output voltages used to guide robots in proximity to various objects.

  4. Capacitive Displacement Sensor With Frequency Readout

    Science.gov (United States)

    Fritsch, Klaus

    1989-01-01

    Simple displacement-measuring circuit senses capacitance between two parallel conducting plates and produces output signal, with frequency proportional to distance between plates. Principle of circuit provides advantages over other methods because of frequency-encoded output and high linearity. Used to measure displacements.

  5. Site Specific Evaluation of Multisensor Capacitance Probes

    Science.gov (United States)

    Multisensor capacitance probes (MCPs) are widely used for measuring soil water content (SWC) at the field scale. Although manufacturers supply a generic MCP calibration, many researchers recognize that MCPs should be calibrated for specific field conditions. MCPs measurements are typically associa...

  6. Capacitors and Resistance-Capacitance Networks.

    Science.gov (United States)

    Balabanian, Norman; Root, Augustin A.

    This programed textbook was developed under a contract with the United States Office of Education as Number 5 in a series of materials for use in an electrical engineering sequence. It is divided into three parts--(1) capacitors, (2) voltage-current relationships, and (3) simple resistance-capacitance networks. (DH)

  7. Negative capacitance in multidomain ferroelectric superlattices

    Science.gov (United States)

    Zubko, Pavlo; Wojdeł, Jacek C.; Hadjimichael, Marios; Fernandez-Pena, Stéphanie; Sené, Anaïs; Luk’Yanchuk, Igor; Triscone, Jean-Marc; Íñiguez, Jorge

    2016-06-01

    The stability of spontaneous electrical polarization in ferroelectrics is fundamental to many of their current applications, which range from the simple electric cigarette lighter to non-volatile random access memories. Research on nanoscale ferroelectrics reveals that their behaviour is profoundly different from that in bulk ferroelectrics, which could lead to new phenomena with potential for future devices. As ferroelectrics become thinner, maintaining a stable polarization becomes increasingly challenging. On the other hand, intentionally destabilizing this polarization can cause the effective electric permittivity of a ferroelectric to become negative, enabling it to behave as a negative capacitance when integrated in a heterostructure. Negative capacitance has been proposed as a way of overcoming fundamental limitations on the power consumption of field-effect transistors. However, experimental demonstrations of this phenomenon remain contentious. The prevalent interpretations based on homogeneous polarization models are difficult to reconcile with the expected strong tendency for domain formation, but the effect of domains on negative capacitance has received little attention. Here we report negative capacitance in a model system of multidomain ferroelectric–dielectric superlattices across a wide range of temperatures, in both the ferroelectric and paraelectric phases. Using a phenomenological model, we show that domain-wall motion not only gives rise to negative permittivity, but can also enhance, rather than limit, its temperature range. Our first-principles-based atomistic simulations provide detailed microscopic insight into the origin of this phenomenon, identifying the dominant contribution of near-interface layers and paving the way for its future exploitation.

  8. Inside-out electrical capacitance tomography

    DEFF Research Database (Denmark)

    Kjærsgaard-Rasmussen, Jimmy; Meyer, Knud Erik

    2011-01-01

    In this work we demonstrate the construction of an ‘inside-out’ sensor geometry for electrical capacitance tomography (ECT). The inside-out geometry has the electrodes placed around a tube, as usual, but measuring ‘outwards’. The flow between the electrodes and an outer tube is reconstructed...

  9. Anisotropic magneto-capacitance in ferromagnetic-plate capacitors

    OpenAIRE

    Haigh, J. A.; Ciccarelli, C; Betz, A. C.; Irvine, A; Novák, V.; Jungwirth, T.; Wunderlich, J.

    2015-01-01

    The capacitance of a parallel plate capacitor can depend on applied magnetic field. Previous studies have identified capacitance changes induced via classical Lorentz force or spin-dependent Zeeman effects. Here we measure a magnetization direction dependent capacitance in parallel-plate capacitors where one plate is a ferromagnetic semiconductor, gallium manganese arsenide. This anisotropic magneto-capacitance is due to the anisotropy in the density of states dependent on the magnetization t...

  10. Membrane capacitance techniques to monitor granule exocytosis in neutrophils.

    OpenAIRE

    Lollike, K; Lindau, M

    1999-01-01

    Cell membranes behave like electrical capacitors and changes in cell capacitance therefore reflect changes in the cell area. Monitoring capacitance can thus be used to study dynamic cellular phenomenon involving rapid changes in cell surface, such as exo- and/or endocytosis. In this review focus is on the use of capacitance techniques to study exocytosis in human neutrophils. We compare the whole-cell and the cell-attached capacitance techniques, and we review the complete literature dealing ...

  11. Negative Quantum Capacitance of Carbon Nanotube Field-Effect Transistors

    OpenAIRE

    Latessa, L.; Pecchia, A.; Di Carlo, A.; P. Lugli

    2004-01-01

    Atomistic density functional theory (DFT) calculations of the capacitance between a metallic cylindric gate and a carbon nanotube (CNT) are reported. Results stressing the predominant effect of quantum capacitance in limiting or even enhancing screening properties of the CNT are shown. Other contributions to the quantum capacitance beyond the electronic density of state (DOS) are pointed out. Negative values of the quantum capacitance are obtained for low-density systems, which correspondingl...

  12. MOS Capacitance-Voltage Characteristics:V.Methods to Enhance the Trapping Capacitance

    Institute of Scientific and Technical Information of China (English)

    揭斌斌; 薩支唐

    2012-01-01

    Low-frequency and High-frequency Capacitance-Voltage (C-V) curves of Silicon Metal-Oxide-Semiconductor Capacitors,showing electron and hole trapping at shallow-level dopant and deep-level generationrecombination-trapping impurities,are presented to illustrate the enhancement of the giant trapping capacitances by physical means via device and circuit designs,in contrast to chemical means via impurity characteristics previously reported.Enhancement is realized by masking the electron or/and hole storage capacitances to make the trapping capacitances dominant at the terminals.Device and materials properties used in the computed CV curves are selected to illustrate experimental realizations for fundamental trapping parameter characterizations and for electrical and optical signal processing applications.

  13. Divisibility of characteristic numbers

    OpenAIRE

    Borghesi, Simone

    2009-01-01

    We use homotopy theory to define certain rational coefficients characteristic numbers with integral values, depending on a given prime number q and positive integer t. We prove the first nontrivial degree formula and use it to show that existence of morphisms between algebraic varieties for which these numbers are not divisible by q give information on the degree of such morphisms or on zero cycles of the target variety.

  14. 3. Theoretical Physics Division

    International Nuclear Information System (INIS)

    For the period September 1980 - Aug 1981, the studies in theoretical physics divisions have been compiled under the following headings: in nuclear physics, nuclear structure, nuclear reactions and intermediate energies; in particle physics, NN and NantiN interactions, dual topological unitarization, quark model and quantum chromodynamics, classical and quantum field theories, non linear integrable equations and topological preons and Grand unified theories. A list of publications, lectures and meetings is included

  15. A 16 × 16 CMOS Capacitive Biosensor Array Towards Detection of Single Bacterial Cell.

    Science.gov (United States)

    Couniot, Numa; Francis, Laurent A; Flandre, Denis

    2016-04-01

    We present a 16 × 16 CMOS biosensor array aiming at impedance detection of whole-cell bacteria. Each 14 μm × 16 μm pixel comprises high-sensitive passivated microelectrodes connected to an innovative readout interface based on charge sharing principle for capacitance-to-voltage conversion and subthreshold gain stage to boost the sensitivity. Fabricated in a 0.25 μm CMOS process, the capacitive array was experimentally shown to perform accurate dielectric measurements of the electrolyte up to electrical conductivities of 0.05 S/m, with maximal sensitivity of 55 mV/fF and signal-to-noise ratio (SNR) of 37 dB. As biosensing proof of concept, real-time detection of Staphylococcus epidermidis binding events was experimentally demonstrated and provides detection limit of ca. 7 bacteria per pixel and sensitivity of 2.18 mV per bacterial cell. Models and simulations show good matching with experimental results and provide a comprehensive analysis of the sensor and circuit system. Advantages, challenges and limits of the proposed capacitive biosensor array are finally described with regards to literature. With its small area and low power consumption, the present capacitive array is particularly suitable for portable point-of-care (PoC) diagnosis tools and lab-on-chip (LoC) systems. PMID:25974947

  16. Comparison of capacitive behavior of activated carbons with different pore structures in aqueous and nonaqueous systems

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shao-yun; LI Xin-hai; WANG Zhi-xing; GUO Hua-jun; PENG Wen-jie

    2008-01-01

    The pore structures of two activated carbons from sawdust with KOH activation and coconut-shell with steam activation for supercapacitor were analyzed by N2 adsorption method. The electrochemical properties of both activated carbons in 6mol/L KOH solution and 1mol/L Et4NPF4/PC were compared, and the effect of pore structure on the capacitance was investigated by cyclic voltammetry, AC impedance and charge-discharge measurements. The results indicate that the capacitance mainly depends on effective surface area, but the power property mainly depends on mesoporosity. At low specific current (1A/g), the maximum specific capacitances of 276.3F/g in aqueous system and 123.9F/g in nonaqueous system can be obtained from sawdust activated carbon with a larger surface area of 1808m2/g, but at a high specific current, the specific capacitance of coconut-shell activated carbon with a higher mesoporosity of 75.1% is more excellent. Activated carbon by KOH activation is fitter for aqueous system and that by steam activation is fitter for nonaqueous system.

  17. One-step electroplating porous graphene oxide electrodes of supercapacitors for ultrahigh capacitance and energy density

    International Nuclear Information System (INIS)

    An electroplating method was used for the first time to synthesize 3D porous graphene oxide (PGO) architectures, exhibiting ultrahigh capacitance and energy density as electrodes of supercapacitors. Scanning electron microscopy illustrated the porous structures which promoted the stability and alleviated the stacking of the graphene oxide layers. As investigated in a three-electrode supercapacitor cell, PGO electrodes exhibited the maximum capacitance and energy of 973 F · g−1 and 98.4 Wh · Kg−1, which are better than current reports and comparable to batteries. At 4 A · g−1 for high-power applications, PGO electrodes reached a capacitance, energy, and power density of 493 F · g−1, 49.9 Wh · Kg−1, and 1700 W · Kg−1, and they retained ∼97.83% of capacitance after 10 000 charge/discharge processes. Furthermore, when the PGO was bent exaggeratedly, it still displayed identical properties, which is of important significance for supporting wearable devices. (paper)

  18. The Capacitive Behaviors of Manganese Dioxide Thin-Film Electrochemical Capacitor Prototypes

    Directory of Open Access Journals (Sweden)

    Suh Cem Pang

    2011-01-01

    Full Text Available We have documented the fabrication of manganese dioxide (MnO2 thin-film electrochemical capacitor (EC prototypes with dual-planar electrode configuration. These EC prototypes exhibited good capacitive behaviors in mild Na2SO4 aqueous electrolyte. Enhanced capacitive behaviors of EC prototypes were observed upon prolonged voltammetric cycling which could be associated with microstructural transformation of MnO2 thin-film electrodes from densely packed plate-like to irregular petal-like surface morphology. Effects of voltammetric scan rates, prolonged voltammetric cycling, electrolyte composition, and electrolyte concentration on the surface morphology of MnO2 thin-film electrodes, and associated capacitive behaviors of MnO2 thin-film EC prototypes were investigated by cyclic voltammetry (CV, electrochemical impedance spectroscopy (EIS, and galvanostatic charge/discharge (GCD techniques. Results of both CV and EIS indicated that thin-film MnO2 EC prototypes exhibited the highest specific capacitance of 327 F/g in 0.2 M Na2SO4 aqueous electrolyte. Being environmentally benign and cheap, MnO2 thin-film electrochemical capacitors have high potential utility as pulsed power sources, as well as load-leveling functions in various consumer electronic devices.

  19. Capacitance and conductance studies on silicon solar cells subjected to 8 MeV electron irradiations

    International Nuclear Information System (INIS)

    The space grade silicon solar cells were irradiated with 8 MeV electrons with doses ranging from 5–100 k Gy. Capacitance and conductance measurements were carried out in order to investigate the anomalous degradation of the cells in the radiation harsh environments and the results are presented in this paper. Detailed and systematic analysis of the frequency-dependent capacitance and conductance measurements were performed to extract the information about the interface trap states. The small increase in density of interface states was observed from the conductance–frequency measurements. The reduction in carrier concentration upon electron irradiation is due to the trapping of charge carriers by the radiation induced trap centres. The Drive Level Capacitance Profiling (DLCP) technique has been applied to study the properties of defects in silicon solar cells. A small variation in responding state densities with measuring frequency was observed and the defect densities are in the range 1015 –1016 cm−3. - Highlights: • Space grade Si solar cells were subjected to 8 MeV electron radiation. • Capacitance and conductance measurements were done before and after irradiation. • Density of interface states and the interface trap time constant is found to increase with increasing electron dose. • The displacement damage formed due to electron is not uniform throughout the active region of c-Si solar cell

  20. Electric field theory and the fallacy of void capacitance

    OpenAIRE

    McAllister, Iain Wilson

    1991-01-01

    The concept of the capacitance of a gaseous void is discussed as applied to electrical insulation science. The most pertinent aspect of the capacitance definition is that of reference to a single-valued potential difference between surfaces. This implies that these surfaces must be surfaces of equipotential. With this essential characteristics the validity of void capacitance is examined

  1. Biorepositories- | Division of Cancer Prevention

    Science.gov (United States)

    Carefully collected and controlled high-quality human biospecimens, annotated with clinical data and properly consented for investigational use, are available through the Division of Cancer Prevention Biorepositories listed in the charts below. Biorepositories Managed by the Division of Cancer Prevention Biorepositories Supported by the Division of Cancer Prevention Related Biorepositories | Information about accessing biospecimens collected from DCP-supported clinical trials and projects.

  2. A simple scheme to generate x-type four-charge entangled states in circuit QED

    Institute of Scientific and Technical Information of China (English)

    Gao Gui-Long; Song Fu-Quan; Huang Shou-Sheng; Wang Hui; Yuan Xian-Zhang; Wang Ming-Feng; Jiang Nian-Quan

    2012-01-01

    We propose a simple scheme to generate x-type four-charge entangled states by using SQUID-based charge qubits capacitively coupled to a transmission line resonator (TLR).The coupling between the superconducting qubit and the TLR can be effectively controlled by properly adjusting the control parameters of the charge qubit.The experimental feasibility of our scheme is also shown.

  3. Design of a High Voltage Bidirectional DC-DC Converter for Driving Capacitive Incremental Actuators usable in Electric Vehicles (EVs)

    OpenAIRE

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.; Maksimovic, Dragan; Sarban, Rahimullah

    2014-01-01

    This paper presents the design of a low input (24 V) and variable high output voltage (0-2.5 kV) bidirectional dc-dc converter for driving a capacitive actuator. The topology is a digitally controlled bidirectional flyback converter with a variable frequency control. The objective is, to design the converter for efficiently charging and discharging the capacitive actuator from 0 V to 2.5 kV and vice versa, respectively. The converter is used to drive a dielectric electro active polymer (DEAP)...

  4. Electrochemical capacitance of iron oxide nanotube (Fe-NT): effect of annealing atmospheres

    Science.gov (United States)

    Sarma, Biplab; Jurovitzki, Abraham L.; Ray, Rupashree S.; Smith, York R.; Mohanty, Swomitra K.; Misra, Mano

    2015-07-01

    The effect of annealing atmosphere on the supercapacitance behavior of iron oxide nanotube (Fe-NT) electrodes has been explored and reported here. Iron oxide nanotubes were synthesized on a pure iron substrate through an electrochemical anodization process in an ethylene glycol solution containing 3% H2O and 0.5 wt.% NH4F. Subsequently, the annealing of the nanotubes was carried out at 500 °C for 2 h in various gas atmospheres such as air, oxygen (O2), nitrogen (N2), and argon (Ar). The morphology and crystal phases evolved after the annealing processes were examined via field emission scanning electron microscopy, x-ray diffraction, Raman spectroscopy, and x-ray photoelectron spectroscopy. The electrochemical capacitance properties of the annealed Fe-NT electrodes were evaluated by conducting cyclic voltammetry (CV), galvanostatic charge-discharge, and electrochemical impedance spectroscopy tests in the Li2SO4 electrolyte. Based on these experiments, it was found that the capacitance of the Fe-NT electrodes annealed in air and O2 atmospheres shows mixed behavior comprising both the electric double layer and pseudocapacitance. However, annealing in N2 and Ar environments resulted in well-defined redox peaks in the CV profiles of the Fe-NT electrodes, which are therefore attributed to the relatively higher pseudonature of the capacitance in these electrodes. Based on the galvanostatic charge-discharge studies, the specific capacitance achieved in the Fe-NT electrode after annealing in Ar was about 300 mF cm-2, which was about twice the value obtained for N2-annealed Fe-NTs and three times higher than those annealed in air and O2. The experiments also demonstrated excellent cycle stability for the Fe-NT electrodes with 83%-85% capacitance retention, even after many charge-discharge cycles, irrespective of the gas atmospheres used during annealing. The increase in the specific capacitance was discussed in terms of increased oxygen vacancies as a result of the

  5. Physics division annual report 2005

    International Nuclear Information System (INIS)

    This report highlights the research performed in 2005 in the Physics Division of Argonne National Laboratory. The Division's programs include operation of ATLAS as a national user facility, nuclear structure and reaction research, nuclear theory, medium energy nuclear research and accelerator research and development. The mission of Nuclear Physics is to understand the origin, evolution and structure of baryonic matter in the universe--the matter that makes up stars, planets and human life itself. The Division's research focuses on innovative new ways to address this mission and 2005 was a year of great progress. One of the most exciting developments is the initiation of the Californium Rare Ion Breeder Upgrade, CARIBU. By combining a Cf-252 fission source, the gas catcher technology developed for rare isotope beams, a high-resolution isobar separator, and charge breeding ECR technology, CARIBU will make hundreds of new neutron-rich isotope beams available for research. The cover illustration shows the anticipated intensities of low-energy beams that become available for low-energy experiments and for injection into ATLAS for reacceleration. CARIBU will be completed in early 2009 and provide us with considerable experience in many of the technologies developed for a future high intensity exotic beam facility. Notable results in research at ATLAS include a measurement of the isomeric states in 252No that helps pin down the single particle structure expected for superheavy elements, and a new low-background measurement of 16N beta-decay to determine the 12C(α, γ)16O reaction rate that is so important in astrophysical environments. Precise mass measurements shed new light on the unitarity of the quark weak-mixing matrix in the search for physics beyond the standard model. ATLAS operated for 4686 hours of research in FY2005 while achieving 95% efficiency of beam delivery for experiments. In Medium-Energy Physics, radium isotopes were trapped in an atom trap for the

  6. Physics division annual report 2005.

    Energy Technology Data Exchange (ETDEWEB)

    Glover, J.; Physics

    2007-03-12

    This report highlights the research performed in 2005 in the Physics Division of Argonne National Laboratory. The Division's programs include operation of ATLAS as a national user facility, nuclear structure and reaction research, nuclear theory, medium energy nuclear research and accelerator research and development. The mission of Nuclear Physics is to understand the origin, evolution and structure of baryonic matter in the universe--the matter that makes up stars, planets and human life itself. The Division's research focuses on innovative new ways to address this mission and 2005 was a year of great progress. One of the most exciting developments is the initiation of the Californium Rare Ion Breeder Upgrade, CARIBU. By combining a Cf-252 fission source, the gas catcher technology developed for rare isotope beams, a high-resolution isobar separator, and charge breeding ECR technology, CARIBU will make hundreds of new neutron-rich isotope beams available for research. The cover illustration shows the anticipated intensities of low-energy beams that become available for low-energy experiments and for injection into ATLAS for reacceleration. CARIBU will be completed in early 2009 and provide us with considerable experience in many of the technologies developed for a future high intensity exotic beam facility. Notable results in research at ATLAS include a measurement of the isomeric states in {sup 252}No that helps pin down the single particle structure expected for superheavy elements, and a new low-background measurement of {sup 16}N beta-decay to determine the {sup 12}C({alpha},{gamma}){sup 16}O reaction rate that is so important in astrophysical environments. Precise mass measurements shed new light on the unitarity of the quark weak-mixing matrix in the search for physics beyond the standard model. ATLAS operated for 4686 hours of research in FY2005 while achieving 95% efficiency of beam delivery for experiments. In Medium-Energy Physics, radium

  7. On the self-excitation mechanisms of Plasma Series Resonance oscillations in single- and multi-frequency capacitive discharges

    CERN Document Server

    Schuengel, Edmund; Korolov, Ihor; Derzsi, Aranka; Donko, Zoltan; Schulze, Julian

    2016-01-01

    The self-excitation of plasma series resonance (PSR) oscillations is a prominent feature in the current of low pressure capacitive radio frequency (RF) discharges. This resonance leads to high frequency oscillations of the charge in the sheaths and enhances electron heating. Up to now, the phenomenon has only been observed in asymmetric discharges. There, the nonlinearity in the voltage balance, which is necessary for the self-excitation of resonance oscillations with frequencies above the applied frequencies, is caused predominantly by the quadratic contribution to the charge-voltage relation of the plasma sheaths. Using PIC/MCC simulations of single- and multi- frequency capacitive discharges and an equivalent circuit model, we demonstrate that other mechanisms such as a cubic contribution to the charge-voltage relation of the plasma sheaths and the time dependent bulk electron plasma frequency can cause the self-excitation of PSR oscillations, as well. These mechanisms have been neglected in previous model...

  8. CAS Academic Divisions in 2001

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ 1.Election of New Members In 2001, 56 scientists were elected new CAS members, including l0 in the Division of Mathematics & Physics, 10 in the Division of Chemistry, 12 in the Division of Biology, nine in the Division of Earth Sciences and 15 in the Division of Engineering Sciences.The average age of the new members is 60.4, and the youngest one is 38 years old. They are now working in nine provinces or municipalities, or governmental departments under the State Council, including 23 outstanding experts working for the CAS.

  9. Polypyrrole/carbon nanotube nanocomposite enhanced the electrochemical capacitance of flexible graphene film for supercapacitors

    Science.gov (United States)

    Lu, Xiangjun; Dou, Hui; Yuan, Changzhou; Yang, Sudong; Hao, Liang; Zhang, Fang; Shen, Laifa; Zhang, Luojiang; Zhang, Xiaogang

    2012-01-01

    The flexible electrodes have important potential applications in energy storage of portable electronic devices for their powerful structural properties. In this work, unique flexible films with polypyrrole/carbon nanotube (PPy/CNT) composite homogeneously distributed between graphene (GN) sheets are successfully prepared by flow-assembly of the mixture dispersion of GN and PPy/CNT. In such layered structure, the coaxial PPy/CNT nanocables can not only enlarge the space between GN sheets but also provide pseudo-capacitance to enhance the total capacitance of electrodes. According to the galvanostatic charge/discharge analysis, the mass and volume specific capacitances of GN-PPy/CNT (52 wt% PPy/CNT) are 211 F g-1 and 122 F cm-3 at a current density of 0.2 A g-1, higher than those of the GN film (73 F g-1 and 79 F cm-3) and PPy/CNT (164 F g-1 and 67 F cm-3). Significantly, the GN-PPy/CNT electrode shows excellent cycling stability (5% capacity loss after 5000 cycles) due to the flexible GN layer and the rigid CNT core synergistical releasing the intrinsic differential strain of PPy chains during long-term charge/discharge cycles.

  10. A Integrated Circuit for a Biomedical Capacitive Pressure Transducer

    Science.gov (United States)

    Smith, Michael John Sebastian

    Medical research has an urgent need for a small, accurate, stable, low-power, biocompatible and inexpensive pressure sensor with a zero to full-scale range of 0-300 mmHg. An integrated circuit (IC) for use with a capacitive pressure transducer was designed, built and tested. The random pressure measurement error due to resolution and non-linearity is (+OR-)0.4 mmHg (at mid-range with a full -scale of 300 mmHg). The long-term systematic error due to falling battery voltage is (+OR-)0.6 mmHg. These figures were calculated from measurements of temperature, supply dependence and non-linearity on completed integrated circuits. The sensor IC allows measurement of temperature to (+OR-)0.1(DEGREES)C to allow for temperature compensation of the transducer. Novel micropower circuit design of the system components enabled these levels of accuracy to be reached. Capacitance is measured by a new ratiometric scheme employing an on -chip reference capacitor. This method greatly reduces the effects of voltage supply, temperature and manufacturing variations on the sensor circuit performance. The limits on performance of the bandgap reference circuit fabricated with a standard bipolar process using ion-implanted resistors were determined. Measurements confirm the limits of temperature stability as approximately (+OR-)300 ppm/(DEGREES)C. An exact analytical expression for the period of the Schmitt trigger oscillator, accounting for non-constant capacitor charging current, was formulated. Experiments to test agreement with theory showed that prediction of the oscillator period was very accurate. The interaction of fundamental and practical limits on the scaling of the transducer size was investigated including a correction to previous theoretical analysis of jitter in an RC oscillator. An areal reduction of 4 times should be achievable.

  11. THE SPRINGBOK SIXTH DIVISION

    Directory of Open Access Journals (Sweden)

    Hertzog Biermann

    2012-02-01

    Full Text Available The Springbok Sixth Division was a mighty armoured force Of men whose ancestors made war in ships, on foot and horse They wrote a stirring chapter in Springbok Martial lore When they went to sunny Italy in Nineteen-Forty-Four.   They were in the Springbok First Team and their modest claim to fame Was their response to the clarion call: "Pay up and play the game!" Their duty they did nobly as their fathers did of old They proudly wore the Sixth Div flash of Springbok green and gold.

  12. Modelling the thermal sterilisation of foods inside packs with two divisions

    OpenAIRE

    Ávila, Isabel M. L. B.; Manso, Maria da Conceição; Silva, Cristina L. M.

    1996-01-01

    A mathematical model was developed to describe the heat transfer during the sterilisation of conduction heating foods inside three dimensional two division rectangular packs. The model uses a standard explicit finite differences method with non-capacitance surface nodes and simulates different pack sizes, food properties and surface heat transfer resistances at the package lid and walls. Taking into account the cooling phase, the sterility value was calculated as a function of positi...

  13. Time-Dependent Negative Capacitance Effects in Al2O3/BaTiO3 Bilayers.

    Science.gov (United States)

    Kim, Yu Jin; Yamada, Hiroyuki; Moon, Taehwan; Kwon, Young Jae; An, Cheol Hyun; Kim, Han Joon; Kim, Keum Do; Lee, Young Hwan; Hyun, Seung Dam; Park, Min Hyuk; Hwang, Cheol Seong

    2016-07-13

    The negative capacitance (NC) effects in ferroelectric materials have emerged as the possible solution to low-power transistor devices and high-charge-density capacitors. Although the steep switching characteristic (subthreshold swing pulse charging. This work revealed that the hysteresis phenomenon in NC devices originated from the dielectric leakage of the dielectric layer. The suppression of charge injection via the dielectric leakage, which usually takes time, inhibits complete ferroelectric polarization switching during a short pulse time. It was demonstrated that a nonhysteretic NC effect can be achieved only within certain limited time and voltage ranges, but that these are sufficient for critical device applications. PMID:27231754

  14. Porous Alumina Based Capacitive MEMS RH Sensor

    CERN Document Server

    Juhasz, L; Timar-Horvath, Veronika; Desmulliez, Marc; Dhariwal, Resh

    2008-01-01

    The aim of a joint research and development project at the BME and HWU is to produce a cheap, reliable, low-power and CMOS-MEMS process compatible capacitive type relative humidity (RH) sensor that can be incorporated into a state-of-the-art, wireless sensor network. In this paper we discuss the preparation of our new capacitive structure based on post-CMOS MEMS processes and the methods which were used to characterize the thin film porous alumina sensing layer. The average sensitivity is approx. 15 pF/RH% which is more than a magnitude higher than the values found in the literature. The sensor is equipped with integrated resistive heating, which can be used for maintenance to reduce drift, or for keeping the sensing layer at elevated temperature, as an alternative method for temperature-dependence cancellation.

  15. The Pyramidal Capacitated Vehicle Routing Problem

    DEFF Research Database (Denmark)

    Lysgaard, Jens

    This paper introduces the Pyramidal Capacitated Vehicle Routing Problem (PCVRP) as a restricted version of the Capacitated Vehicle Routing Problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the Pyramidal Traveling Salesman Problem (PTSP). A pyramidal...... of a pyramidal route is such that its traversal can be divided in two parts, where on the first part of the route, customers are visited in nondecreasing distance from the depot, and on the remaining part of the route, customers are visited in nonincreasing distance from the depot. Such a route shape is indeed...... found in many optimal solutions to CVRP instances. An optimal solution to the PCVRP may therefore be useful in itself as a heuristic solution to the CVRP. Further, an attempt can be made to find an even better CVRP solution by solving a TSP, possibly leading to a non-pyramidal route, for each...

  16. Automatic Power Factor Correction Using Capacitive Bank

    Directory of Open Access Journals (Sweden)

    Mr.Anant Kumar Tiwari,

    2014-02-01

    Full Text Available The power factor correction of electrical loads is a problem common to all industrial companies. Earlier the power factor correction was done by adjusting the capacitive bank manually [1]. The automated power factor corrector (APFC using capacitive load bank is helpful in providing the power factor correction. Proposed automated project involves measuring the power factor value from the load using microcontroller. The design of this auto-adjustable power factor correction is to ensure the entire power system always preserving unity power factor. The software and hardware required to implement the suggested automatic power factor correction scheme are explained and its operation is described. APFC thus helps us to decrease the time taken to correct the power factor which helps to increase the efficiency.

  17. Layer resolved capacitive probing of graphene bilayers

    Science.gov (United States)

    Zibrov, Alexander; Parmentier, François; Li, Jia; Wang, Lei; Hunt, Benjamin; Dean, Cory; Hone, James; Taniguchi, Takashi; Watanabe, Kenji; Young, Andrea

    Compared to single layer graphene, graphene bilayers have an additional ``which-layer'' degree of freedom that can be controlled by an external electric field in a dual-gated device geometry. We describe capacitance measurements capable of directly probing this degree of freedom. By performing top gate, bottom gate, and penetration field capacitance measurements, we directly extract layer polarization of both Bernal and twisted bilayers. We will present measurements of hBN encapsulated bilayers at both zero and high magnetic field, focusing on the physics of the highly degenerate zero-energy Landau level in the high magnetic field limit where spin, valley, and layer degeneracy are all lifted by electronic interactions.

  18. CMOS Integrated Capacitive DC-DC Converters

    CERN Document Server

    Van Breussegem, Tom

    2013-01-01

    This book provides a detailed analysis of all aspects of capacitive DC-DC converter design: topology selection, control loop design and noise mitigation. Readers will benefit from the authors’ systematic overview that starts from the ground up, in-depth circuit analysis and a thorough review of recently proposed techniques and design methodologies.  Not only design techniques are discussed, but also implementation in CMOS is shown, by pinpointing the technological opportunities of CMOS and demonstrating the implementation based on four state-of-the-art prototypes.  Provides a detailed analysis of all aspects of capacitive DC-DC converter design;  Analyzes the potential of this type of DC-DC converter and introduces a number of techniques to unleash their full potential; Combines system theory with practical implementation techniques; Includes unique analysis of CMOS technology for this application; Provides in-depth analysis of four fabricated prototypes.

  19. THERMAL DRIFT CHARACTERISTICS OF CAPACITIVE PRESSURE SENSORS

    OpenAIRE

    ABDELAZIZ BEDDIAF; FOUAD KERROUR; SALAH KEMOUCHE

    2016-01-01

    The capacitive pressure sensors based on silicon are characterized by their very high sensitivities and their low power consumption. Nevertheless, their thermal behavior remains more or less unpredictable because they can indicate very high thermal coefficients. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristics drift. In this study, we modeled the thermal behavior of this sensors, using Finite Element Analysis (FE...

  20. Ultra-High-Frequency Capacitive Displacement Sensor

    Science.gov (United States)

    Vanzandt, Thomas R.; Kenny, Thomas W.; Kaiser, William J.

    1994-01-01

    Improved class of compact, high-resolution capacitive displacement sensors operates at excitation frequency of 915 MHz and measures about 7.5 by 4 by 2 centimeters. Contains commercially available 915-MHz oscillator and transmission-line resonator. Resonator contains stripline inductor in addition to variable capacitor. Ultrahigh excitation frequency offers advantages of resolution and frequency response. Not deleteriously affected by mechanical overdriving, or contact between electrodes.

  1. Capacitive Sensors And Targets Would Measure Alignments

    Science.gov (United States)

    Jenstrom, Del T.

    1994-01-01

    Multiple capacitive sensors and active targets used to measure distance between, and relative orientation of, two objects. Sensed target signals processed and used by control systems to align objects to be joined. Shapes, sizes, and layouts of sensors and targets optimized for specific application. Particular layout of targets and sensors enables determination of relative position and orientation of two objects in all six degrees of freedom.

  2. Development of a capacitive bioimpedance measurement system

    OpenAIRE

    Gómez Abad, Daniel

    2009-01-01

    Bioelectrical impedance spectroscopy (BIS) is a well-established and non-invasive method to determine and monitor body composition. Commercially available bioelectrical impedance systems use coated hydrogel-aluminium electrodes, where the hydrogel acts as an adhesive and as an electrolytic medium. The gel/adhesive is physiologically inert over short periods. However, when used over longer periods, hydrogel-aluminium electrodes present limitations, which capacitive electrodes ma...

  3. The fringe capacitance formula of microstructures

    International Nuclear Information System (INIS)

    This paper presents a fringe capacitance formula of microstructures. The formula is derived by curve fitting on ANSYS simulation results. Compared with the ANSYS and experimental results, the deviation is within ±2%. The application to determine the pull-in voltage of an electrostatic micro-beam is demonstrated, which agrees very well with the experimental data. The formula presented is very accurate, yields explicit physical meanings and is applicable to common dimension ranges for MEMS devices. (paper)

  4. Conductive two-dimensional titanium carbide 'clay' with high volumetric capacitance.

    Science.gov (United States)

    Ghidiu, Michael; Lukatskaya, Maria R; Zhao, Meng-Qiang; Gogotsi, Yury; Barsoum, Michel W

    2014-12-01

    Safe and powerful energy storage devices are becoming increasingly important. Charging times of seconds to minutes, with power densities exceeding those of batteries, can in principle be provided by electrochemical capacitors--in particular, pseudocapacitors. Recent research has focused mainly on improving the gravimetric performance of the electrodes of such systems, but for portable electronics and vehicles volume is at a premium. The best volumetric capacitances of carbon-based electrodes are around 300 farads per cubic centimetre; hydrated ruthenium oxide can reach capacitances of 1,000 to 1,500 farads per cubic centimetre with great cyclability, but only in thin films. Recently, electrodes made of two-dimensional titanium carbide (Ti3C2, a member of the 'MXene' family), produced by etching aluminium from titanium aluminium carbide (Ti3AlC2, a 'MAX' phase) in concentrated hydrofluoric acid, have been shown to have volumetric capacitances of over 300 farads per cubic centimetre. Here we report a method of producing this material using a solution of lithium fluoride and hydrochloric acid. The resulting hydrophilic material swells in volume when hydrated, and can be shaped like clay and dried into a highly conductive solid or rolled into films tens of micrometres thick. Additive-free films of this titanium carbide 'clay' have volumetric capacitances of up to 900 farads per cubic centimetre, with excellent cyclability and rate performances. This capacitance is almost twice that of our previous report, and our synthetic method also offers a much faster route to film production as well as the avoidance of handling hazardous concentrated hydrofluoric acid. PMID:25470044

  5. Conductive two-dimensional titanium carbide `clay' with high volumetric capacitance

    Science.gov (United States)

    Ghidiu, Michael; Lukatskaya, Maria R.; Zhao, Meng-Qiang; Gogotsi, Yury; Barsoum, Michel W.

    2014-12-01

    Safe and powerful energy storage devices are becoming increasingly important. Charging times of seconds to minutes, with power densities exceeding those of batteries, can in principle be provided by electrochemical capacitors--in particular, pseudocapacitors. Recent research has focused mainly on improving the gravimetric performance of the electrodes of such systems, but for portable electronics and vehicles volume is at a premium. The best volumetric capacitances of carbon-based electrodes are around 300 farads per cubic centimetre; hydrated ruthenium oxide can reach capacitances of 1,000 to 1,500 farads per cubic centimetre with great cyclability, but only in thin films. Recently, electrodes made of two-dimensional titanium carbide (Ti3C2, a member of the `MXene' family), produced by etching aluminium from titanium aluminium carbide (Ti3AlC2, a `MAX' phase) in concentrated hydrofluoric acid, have been shown to have volumetric capacitances of over 300 farads per cubic centimetre. Here we report a method of producing this material using a solution of lithium fluoride and hydrochloric acid. The resulting hydrophilic material swells in volume when hydrated, and can be shaped like clay and dried into a highly conductive solid or rolled into films tens of micrometres thick. Additive-free films of this titanium carbide `clay' have volumetric capacitances of up to 900 farads per cubic centimetre, with excellent cyclability and rate performances. This capacitance is almost twice that of our previous report, and our synthetic method also offers a much faster route to film production as well as the avoidance of handling hazardous concentrated hydrofluoric acid.

  6. Polyaniline nanowire electrodes with high capacitance synthesized by a simple approach

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Li; Zhao, Guangyu; Wang, Yan, E-mail: wangy_msn@hotmail.com

    2013-01-01

    Polyaniline (PANI) nanowire electrodes were successfully synthesized by electrodeposition using starch as template. The electrodes were characterized with scanning electron microscope (SEM) and X-ray diffraction technique. SEM images showed that the electrodes electrodeposited using the starch template had nanowire morphology, but the PANI electrodeposited in absent solution had agglomerate block morphology. Cyclic voltammograms at different scan rates and charge-discharge tests were performed in 0.5 M H{sub 2}SO{sub 4} aqueous solution. The PANI nanowire electrodes had a high capacitance (882 F g{sup -1}) and a high stability (5% capacity loss after 500 cycles). - Highlights: Black-Right-Pointing-Pointer Polyaniline nanowire electrodes were successfully synthesized by electrodeposition using starch as template. Black-Right-Pointing-Pointer The PANI nanowire electrodes had a high capacitance (882 F g{sup -1}). Black-Right-Pointing-Pointer The PANI nanowire electrodes had a high stability (5% capacity loss after 500 cycles).

  7. Energy from CO2 using capacitive electrodes--theoretical outline and calculation of open circuit voltage.

    Science.gov (United States)

    Paz-Garcia, J M; Schaetzle, O; Biesheuvel, P M; Hamelers, H V M

    2014-03-15

    Recently, a new technology has been proposed for the utilization of energy from CO2 emissions (Hamelers et al., 2014). The principle consists of controlling the dilution process of CO2-concentrated gas (e.g., exhaust gas) into CO2-dilute gas (e.g., air) thereby extracting a fraction of the released mixing energy. In this paper, we describe the theoretical fundamentals of this technology when using a pair of charge-selective capacitive electrodes. We focus on the behavior of the chemical system consisting of CO2 gas dissolved in water or monoethanolamine solution. The maximum voltage given for the capacitive cell is theoretically calculated, based on the membrane potential. The different aspects that affect this theoretical maximum value are discussed.

  8. 116 dB dynamic range CMOS readout circuit for MEMS capacitive accelerometer

    International Nuclear Information System (INIS)

    A high stability in-circuit reprogrammable technique control system for a capacitive MEMS accelerometer is presented. Modulation and demodulation are used to separate the signal from the low frequency noise. A low-noise low-offset charge integrator is employed in this circuit to implement a capacitance-to-voltage converter and minimize the noise and offset. The application-specific integrated circuit (ASIC) is fabricated in a 0.5 μm one-ploy three-metal CMOS process. The measured results of the proposed circuit show that the noise floor of the ASIC is −116 dBV, the sensitivity of the accelerometer is 66 mV/g with a nonlinearity of 0.5%. The chip occupies 3.5 × 2.5 mm2 and the current is 3.5 mA. (semiconductor integrated circuits)

  9. Evaluation of EHD films by electrical capacitance

    Science.gov (United States)

    Jablonka, Karolina; Glovnea, Romeo; Bongaerts, Jeroen

    2012-09-01

    The elastohydrodynamic (EHD) lubrication regime occurs in many machine elements where a combination of hydrodynamic effect, elastic deformation of the loaded surfaces and increase in the viscosity of the lubricant with pressure ensures the formation of a very thin, but continuous film of lubricant separating the contacting surfaces. Electrical methods to determine this film's thickness have preceded optical methods, which are widely used today. Although they generally give more qualitative thickness information, electrical methods have the main advantage that they can be applied to metallic contacts in machines, which makes them useful tools in the study of elastohydrodynamically lubricated contacts. This paper is part of a larger study on the application of electrical capacitance for the evaluation of film formation in EHD contacts. The main focus is on the quantitative measurements of film thickness using electrical capacitance. A new approach allowing the lubricant film thickness to be extracted from the measured capacitance is developed using a chromium-coated glass disc and subsequently applied to a steel-on-steel contact. The results show good agreement with optical measurements and theoretical models over a range of film thickness.

  10. Multi-Channel Capacitive Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Bingnan Wang

    2016-01-01

    Full Text Available In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved.

  11. Carbon Materials for Chemical Capacitive Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Y.; Dou, Y.; Zhao, D.; Fulvio, P. F.; Mayes, R. T.; Dai, S.

    2011-09-26

    Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.

  12. Carbon materials for chemical capacitive energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Yunpu; Zhao, Dongyuan [Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Key Laboratory of Molecular Engineering of Polymers of the Chinese, Ministry of Education, Laboratory of Advanced Materials, Fudan University, Shanghai (China); Dou, Yuqian [Department of Chemistry, Northeastern University, Shenyang (China); Fulvio, Pasquale F.; Mayes, Richard T.; Dai, Sheng [Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2011-11-09

    Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Multi-Channel Capacitive Sensor Arrays.

    Science.gov (United States)

    Wang, Bingnan; Long, Jiang; Teo, Koon Hoo

    2016-01-01

    In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved. PMID:26821023

  14. Effect of astaxanthin on human sperm capacitation.

    Science.gov (United States)

    Donà, Gabriella; Kožuh, Ivana; Brunati, Anna Maria; Andrisani, Alessandra; Ambrosini, Guido; Bonanni, Guglielmo; Ragazzi, Eugenio; Armanini, Decio; Clari, Giulio; Bordin, Luciana

    2013-06-01

    In order to be able to fertilize oocytes, human sperm must undergo a series of morphological and structural alterations, known as capacitation. It has been shown that the production of endogenous sperm reactive oxygen species (ROS) plays a key role in causing cells to undergo a massive acrosome reaction (AR). Astaxanthin (Asta), a photo-protective red pigment belonging to the carotenoid family, is recognized as having anti-oxidant, anti-cancer, anti-diabetic and anti-inflammatory properties and is present in many dietary supplements. This study evaluates the effect of Asta in a capacitating buffer which induces low ROS production and low percentages of acrosome-reacted cells (ARC). Sperm cells were incubated in the presence or absence of increasing concentrations of Asta or diamide (Diam) and analyzed for their ROS production, Tyr-phosphorylation (Tyr-P) pattern and percentages of ARC and non-viable cells (NVC). Results show that Asta ameliorated both sperm head Tyr-P and ARC values without affecting the ROS generation curve, whereas Diam succeeded in enhancing the Tyr-P level but only of the flagellum without increasing ARC values. It is suggested that Asta can be inserted in the membrane and therefore create capacitation-like membrane alteration which allow Tyr-P of the head. Once this has occurred, AR can take place and involves a higher numbers of cells. PMID:23736766

  15. Effect of Astaxanthin on Human Sperm Capacitation

    Directory of Open Access Journals (Sweden)

    Luciana Bordin

    2013-06-01

    Full Text Available In order to be able to fertilize oocytes, human sperm must undergo a series of morphological and structural alterations, known as capacitation. It has been shown that the production of endogenous sperm reactive oxygen species (ROS plays a key role in causing cells to undergo a massive acrosome reaction (AR. Astaxanthin (Asta, a photo-protective red pigment belonging to the carotenoid family, is recognized as having anti-oxidant, anti-cancer, anti-diabetic and anti-inflammatory properties and is present in many dietary supplements. This study evaluates the effect of Asta in a capacitating buffer which induces low ROS production and low percentages of acrosome-reacted cells (ARC. Sperm cells were incubated in the presence or absence of increasing concentrations of Asta or diamide (Diam and analyzed for their ROS production, Tyr-phosphorylation (Tyr-P pattern and percentages of ARC and non-viable cells (NVC. Results show that Asta ameliorated both sperm head Tyr-P and ARC values without affecting the ROS generation curve, whereas Diam succeeded in enhancing the Tyr-P level but only of the flagellum without increasing ARC values. It is suggested that Asta can be inserted in the membrane and therefore create capacitation-like membrane alteration which allow Tyr-P of the head. Once this has occurred, AR can take place and involves a higher numbers of cells.

  16. Capacitive Structures for Gas and Biological Sensing

    KAUST Repository

    Sapsanis, Christos

    2015-04-01

    The semiconductor industry was benefited by the advances in technology in the last decades. This fact has an impact on the sensors field, where the simple transducer was evolved into smart miniaturized multi-functional microsystems. However, commercially available gas and biological sensors are mostly bulky, expensive, and power-hungry, which act as obstacles to mass use. The aim of this work is gas and biological sensing using capacitive structures. Capacitive sensors were selected due to its design simplicity, low fabrication cost, and no DC power consumption. In the first part, the dominant structure among interdigitated electrodes (IDEs), fractal curves (Peano and Hilbert) and Archimedean spiral was investigated from capacitance density perspective. The investigation consists of geometrical formula calculations, COMSOL Multiphysics simulations and cleanroom fabrication of the capacitors on a silicon substrate. Moreover, low-cost fabrication on flexible plastic PET substrate was conducted outside cleanroom with rapid prototyping using a maskless laser etching. The second part contains the humidity, Volatile Organic compounds (VOCs) and Ammonia sensing of polymers, Polyimide and Nafion, and metal-organic framework (MOF), Cu(bdc)2.xH2O using IDEs and tested in an automated gas setup for experiment control and data extraction. The last part includes the biological sensing of C - reactive protein (CRP) quantification, which is considered as a biomarker of being prone to cardiac diseases and Bovine serum albumin (BSA) protein quantification, which is used as a reference for quantifying unknown proteins.

  17. Deconstructing Calculation Methods, Part 4: Division

    Science.gov (United States)

    Thompson, Ian

    2008-01-01

    In the final article of a series of four, the author deconstructs the primary national strategy's approach to written division. The approach to division is divided into five stages: (1) mental division using partition; (2) short division of TU / U; (3) "expanded" method for HTU / U; (4) short division of HTU / U; and (5) long division. [For part…

  18. Graphene Supported Ni-based Nanocomposites as Electrode Materials with High Capacitance

    International Nuclear Information System (INIS)

    Graphical abstract: All the Ni-based graphene materials show a relatively high capacitance at the scan rate of 5 mV s−1. 15%Ni(OH)2/graphene shows the highest specific capacitance of 2077 F g−1 and 15%Ni/graphene by calcined 15%Ni(OH)2/graphene has a low capacitance of 633 F g−1. The cycle-life tests of β-Ni(OH)2 and Ni-based/graphene materials were conducted by 500 cycles between 0.0 and 0.7 V at a scan rate of 50 mV s−1. The capacitance of 15%Ni(OH)2/graphene is 965 F g−1 after 500 cycles. - Highlights: • Ni based/graphene materials are prepared with a facile hydrothermal method. • 15%Ni(OH)2/graphene shows the highest specific capacitance of 2077 Fg-1. • 15%Ni/graphene by calcined 15%Ni(OH)2/graphene has a low capacitance of 633 Fg-1. • The capacitance of 15%Ni(OH)2/graphene is 965 Fg-1 after 500 cycles at 50 mVs-1. - Abstract: The Ni-based/graphene materials were synthesized by a simple hydrothermal method, using the graphene oxide as the support precursor. The textural and structural properties of the as-prepared Ni-based/graphene samples were fully characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermalgravimetric analysis and Fourier transform infrared spectroscopy, respectively. Electrochemical properties were examined by cyclic voltammetry, electrochemical impedance spectroscopy and cyclic charge-discharge tests. The results showed that the 15%-β-Ni(OH)2/graphene had the high specific capacity of 2077 F g−1 at 5 mV s−1 in the range of 0.0–0.7 V (vs. Ag/AgCl) and had a good cycle life with 965 F g−1 after 500 cycles at 50 mV s−1

  19. Distributed Capacitive Sensor for Sample Mass Measurement

    Science.gov (United States)

    Toda, Risaku; McKinney, Colin; Jackson, Shannon P.; Mojarradi, Mohammad; Manohara, Harish; Trebi-Ollennu, Ashitey

    2011-01-01

    Previous robotic sample return missions lacked in situ sample verification/ quantity measurement instruments. Therefore, the outcome of the mission remained unclear until spacecraft return. In situ sample verification systems such as this Distributed Capacitive (DisC) sensor would enable an unmanned spacecraft system to re-attempt the sample acquisition procedures until the capture of desired sample quantity is positively confirmed, thereby maximizing the prospect for scientific reward. The DisC device contains a 10-cm-diameter pressure-sensitive elastic membrane placed at the bottom of a sample canister. The membrane deforms under the weight of accumulating planetary sample. The membrane is positioned in close proximity to an opposing rigid substrate with a narrow gap. The deformation of the membrane makes the gap narrower, resulting in increased capacitance between the two parallel plates (elastic membrane and rigid substrate). C-V conversion circuits on a nearby PCB (printed circuit board) provide capacitance readout via LVDS (low-voltage differential signaling) interface. The capacitance method was chosen over other potential approaches such as the piezoelectric method because of its inherent temperature stability advantage. A reference capacitor and temperature sensor are embedded in the system to compensate for temperature effects. The pressure-sensitive membranes are aluminum 6061, stainless steel (SUS) 403, and metal-coated polyimide plates. The thicknesses of these membranes range from 250 to 500 m. The rigid substrate is made with a 1- to 2-mm-thick wafer of one of the following materials depending on the application requirements glass, silicon, polyimide, PCB substrate. The glass substrate is fabricated by a microelectromechanical systems (MEMS) fabrication approach. Several concentric electrode patterns are printed on the substrate. The initial gap between the two plates, 100 m, is defined by a silicon spacer ring that is anodically bonded to the glass

  20. Physics Division annual report 2004

    International Nuclear Information System (INIS)

    This report highlights the research performed in 2004 in the Physics Division of Argonne National Laboratory. The Division's programs include operation of ATLAS as a national user facility, nuclear structure and reaction research, nuclear theory, medium energy nuclear research and accelerator research and development. The intellectual challenges of this research represent some of the most fundamental challenges in modern science, shaping our understanding of both tiny objects at the center of the atom and some of the largest structures in the universe. A great strength of these efforts is the critical interplay of theory and experiment. Notable results in research at ATLAS include a measurement of the charge radius of He-6 in an atom trap and its explanation in ab-initio calculations of nuclear structure. Precise mass measurements on critical waiting point nuclei in the rapid-proton-capture process set the time scale for this important path in nucleosynthesis. An abrupt fall-off was identified in the subbarrier fusion of several heavy-ion systems. ATLAS operated for 5559 hours of research in FY2004 while achieving 96% efficiency of beam delivery for experiments. In Medium Energy Physics, substantial progress was made on a long-term experiment to search for the violation of time-reversal invariance using trapped Ra atoms. New results from HERMES reveal the influence of quark angular momentum. Experiments at JLAB search for evidence of color transparency in rho-meson production and study the EMC effect in helium isotopes. New theoretical results include a Poincare covariant description of baryons as composites of confined quarks and non-point-like diquarks. Green's function Monte Carlo techniques give accurate descriptions of the excited states of light nuclei and these techniques been extended to scattering states for astrophysics studies. A theoretical description of the phenomena of proton radioactivity has been extended to triaxial nuclei. Argonne continues to

  1. Physics Division annual report 2004.

    Energy Technology Data Exchange (ETDEWEB)

    Glover, J.

    2006-04-06

    This report highlights the research performed in 2004 in the Physics Division of Argonne National Laboratory. The Division's programs include operation of ATLAS as a national user facility, nuclear structure and reaction research, nuclear theory, medium energy nuclear research and accelerator research and development. The intellectual challenges of this research represent some of the most fundamental challenges in modern science, shaping our understanding of both tiny objects at the center of the atom and some of the largest structures in the universe. A great strength of these efforts is the critical interplay of theory and experiment. Notable results in research at ATLAS include a measurement of the charge radius of He-6 in an atom trap and its explanation in ab-initio calculations of nuclear structure. Precise mass measurements on critical waiting point nuclei in the rapid-proton-capture process set the time scale for this important path in nucleosynthesis. An abrupt fall-off was identified in the subbarrier fusion of several heavy-ion systems. ATLAS operated for 5559 hours of research in FY2004 while achieving 96% efficiency of beam delivery for experiments. In Medium Energy Physics, substantial progress was made on a long-term experiment to search for the violation of time-reversal invariance using trapped Ra atoms. New results from HERMES reveal the influence of quark angular momentum. Experiments at JLAB search for evidence of color transparency in rho-meson production and study the EMC effect in helium isotopes. New theoretical results include a Poincare covariant description of baryons as composites of confined quarks and non-point-like diquarks. Green's function Monte Carlo techniques give accurate descriptions of the excited states of light nuclei and these techniques been extended to scattering states for astrophysics studies. A theoretical description of the phenomena of proton radioactivity has been extended to triaxial nuclei. Argonne

  2. Accelerator Technology Division

    Science.gov (United States)

    1992-04-01

    In fiscal year (FY) 1991, the Accelerator Technology (AT) division continued fulfilling its mission to pursue accelerator science and technology and to develop new accelerator concepts for application to research, defense, energy, industry, and other areas of national interest. This report discusses the following programs: The Ground Test Accelerator Program; APLE Free-Electron Laser Program; Accelerator Transmutation of Waste; JAERI, OMEGA Project, and Intense Neutron Source for Materials Testing; Advanced Free-Electron Laser Initiative; Superconducting Super Collider; The High-Power Microwave Program; (Phi) Factory Collaboration; Neutral Particle Beam Power System Highlights; Accelerator Physics and Special Projects; Magnetic Optics and Beam Diagnostics; Accelerator Design and Engineering; Radio-Frequency Technology; Free-Electron Laser Technology; Accelerator Controls and Automation; Very High-Power Microwave Sources and Effects; and GTA Installation, Commissioning, and Operations.

  3. Preparation of highly capacitive polyaniline/black TiO2 nanotubes as supercapacitor electrode by hydrogenation and electrochemical deposition

    International Nuclear Information System (INIS)

    Highlights: • PANI/H-TiO2 NTs is prepared by hydrogenation and electrochemical deposition. • PANI/H-TiO2 NTs exhibits higher capacitance than PANI/TiO2 NTs. • PANI/H-TiO2 NTs achieves the highest capacitance value of 999 F g−1 based on TiO2 NTs. • PANI/H-TiO2 NTs has remarkable cycling stability and great rate capability. - Abstract: A combination method of hydrogenated reduction and electrochemical deposition is employed to prepare highly capacitive polyaniline/black TiO2 nanotubes (PANI/H-TiO2 NTs) for supercapacitor. PANI/H-TiO2 NTs shows capacitance of 999 F g−1 at the current density of 0.6 A g−1. To the best of our knowledge, this result is the highest value based on TiO2 nanotubes (TiO2 NTs) or its composites (PANI/TiO2 NTs) for supercapacitor electrode. Moreover, PANI/H-TiO2 NTs also shows remarkable long-term cycling stability with only 29.8% reduction of the initial capacitance at a current density of 24.0 A g−1 after 2000 charge-discharge cycles, as well as great rate capability. The electrochemical impedance spectroscopy of PANI/H-TiO2 NTs shows that this electrode has low resistance. The solution resistance and charge-transfer resistance is as low as 0.1554 and 2.723 Ω cm−2, respectively, which indicate the better electronic transport ability and high charge-transfer rate of PANI/H-TiO2 NTs

  4. Physics division annual report 1999

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, K., ed.; Physics

    2000-12-06

    This report summarizes the research performed in the past year in the Argonne Physics Division. The Division's programs include operation of ATLAS as a national heavy-ion user facility, nuclear structure and reaction research with beams of heavy ions, accelerator research and development especially in superconducting radio frequency technology, nuclear theory and medium energy nuclear physics. The Division took significant strides forward in its science and its initiatives for the future in the past year. Major progress was made in developing the concept and the technology for the future advanced facility of beams of short-lived nuclei, the Rare Isotope Accelerator. The scientific program capitalized on important instrumentation initiatives with key advances in nuclear science. In 1999, the nuclear science community adopted the Argonne concept for a multi-beam superconducting linear accelerator driver as the design of choice for the next major facility in the field a Rare Isotope Accelerator (WA) as recommended by the Nuclear Science Advisory Committee's 1996 Long Range Plan. Argonne has made significant R&D progress on almost all aspects of the design concept including the fast gas catcher (to allow fast fragmentation beams to be stopped and reaccelerated) that in large part defined the RIA concept the superconducting rf technology for the driver accelerator, the multiple-charge-state concept (to permit the facility to meet the design intensity goals with existing ion-source technology), and designs and tests of high-power target concepts to effectively deal with the full beam power of the driver linac. An NSAC subcommittee recommended the Argonne concept and set as tie design goal Uranium beams of 100-kwatt power at 400 MeV/u. Argonne demonstrated that this goal can be met with an innovative, but technically in-hand, design. The heavy-ion research program focused on GammaSphere, the premier facility for nuclear structure gamma-ray studies. One example

  5. Charge fluctuations in open chaotic cavities

    International Nuclear Information System (INIS)

    We present a discussion of the charge response and the charge fluctuations of mesoscopic chaotic cavities in terms of a generalized Wigner-Smith matrix. The Wigner-Smith matrix is well known in investigations of time-delay of quantum scattering. It is expressed in terms of the scattering matrix and its derivatives with energy. We consider a similar matrix but instead of an energy derivative, we investigate the derivative with regard to the electric potential. The resulting matrix is then the operator of charge. If this charge operator is combined with a self-consistent treatment of Coulomb interaction, the charge operator determines the capacitance of the system, the non-dissipative ac-linear response, the RC-time with a novel charge relaxation resistance, and in the presence of transport a resistance that governs the displacement currents induced into a nearby conductor. In particular, these capacitances and resistances determine the relaxation rate and dephasing rate of a nearby qubit (a double quantum dot). We discuss the role of screening of mesoscopic chaotic detectors. Coulomb interaction effects in quantum pumping and in photon assisted electron-hole shot noise are treated similarly. For the latter, we present novel results for chaotic cavities with non-ideal leads

  6. Modeling of stored charge in metallized biaxially oriented polypropylene film capacitors based on charging current measurement.

    Science.gov (United States)

    Li, Hua; Wang, Bowen; Li, Zhiwei; Liu, De; Lin, Fuchang; Dai, Ling; Zhang, Qin; Chen, Yaohong

    2013-10-01

    Metallized biaxially oriented polypropylene film (BOPP) capacitors are widely used in pulsed power systems. When the capacitor is used as the energy storage equipment under high electric field, more charges should be provided to maintain the voltage of the capacitor. This should be ascribed to the completion of the slow polarization which may take several hours or even longer. This paper focuses on the stored charge in metallized BOPP film capacitors. The modeling of the stored charge by the equivalent conversion of circuits is conducted to analyse the slow polarization in the BOPP film. The 3-RC network is proposed to represent the time-dependent charge stored in the capacitor. A charging current measurement system is established to investigate the charge storage property of the capacitor. The measurement system can measure the long time charging current with a sampling rate of 300 Hz. The total charge calculated by the charging current indicates that the stored charge in the capacitor under the electric field of 400 V/μm is 13.5% larger than the product of the voltage and the capacitance measured by the AC bridge. The nonlinear effect of the electric field on the slow polarization charge is also demonstrated. And the simulation of charge storage based on the 3-RC network can match well with the trend of the stored charge increasing with the time. PMID:24182144

  7. Modeling of stored charge in metallized biaxially oriented polypropylene film capacitors based on charging current measurement

    Science.gov (United States)

    Li, Hua; Wang, Bowen; Li, Zhiwei; Liu, De; Lin, Fuchang; Dai, Ling; Zhang, Qin; Chen, Yaohong

    2013-10-01

    Metallized biaxially oriented polypropylene film (BOPP) capacitors are widely used in pulsed power systems. When the capacitor is used as the energy storage equipment under high electric field, more charges should be provided to maintain the voltage of the capacitor. This should be ascribed to the completion of the slow polarization which may take several hours or even longer. This paper focuses on the stored charge in metallized BOPP film capacitors. The modeling of the stored charge by the equivalent conversion of circuits is conducted to analyse the slow polarization in the BOPP film. The 3-RC network is proposed to represent the time-dependent charge stored in the capacitor. A charging current measurement system is established to investigate the charge storage property of the capacitor. The measurement system can measure the long time charging current with a sampling rate of 300Hz. The total charge calculated by the charging current indicates that the stored charge in the capacitor under the electric field of 400 V/μm is 13.5% larger than the product of the voltage and the capacitance measured by the AC bridge. The nonlinear effect of the electric field on the slow polarization charge is also demonstrated. And the simulation of charge storage based on the 3-RC network can match well with the trend of the stored charge increasing with the time.

  8. Numerical analysis of capacitive pressure micro-sensors

    Institute of Scientific and Technical Information of China (English)

    WANG; Xiaomin; LI; Mingxuan; WANG; Chenghao

    2005-01-01

    Pseudo-spectral method is used to numerically model the diaphragm deflection of capacitive pressure micro-sensor under uniform load. The relationship between the capacitance of the micro-sensor and the load is then analyzed after the description of the computational principle. For normal mode micro-sensor, the tensile force on the diaphragm can be ignored and thereby the capacitance increases linearly with the load increase only when the load is so small that the resultant deflection is less than the diaphragm thickness. The linear relationship between the capacitance and the load turns to be nonlinear thereafter and the capacitance rises dramatically with the constant increase of the load. For touch mode micro-sensor, an algorithm to determine the touch radius of the diaphragm and substrate is presented and the curve of capacitance versus load is shown on the numerical results laying a theoretical foundation for micro-sensor design.

  9. Accurate sizing of supercapacitors storage system considering its capacitance variation.

    OpenAIRE

    Trieste, Sony; Bourguet, Salvy; Olivier, Jean-Christophe; Loron, Luc; Le Claire, Jean-Claude

    2011-01-01

    This paper highlights the energy errors made for the design of supercapacitors used as a main energy source. First of all, the paper presents the two definitions of capacitance of a capacitance-voltage dependent material. The number of supercapacitors is important for the application purchasing cost. That is why the paper introduces an analytical model and an electrical model along with an identification method for the capacitance variation. This variation is presented and compared to the man...

  10. Probing Quantum Capacitance in a 3D Topological Insulator

    OpenAIRE

    Kozlov, D. A.; Bauer, Dominik; Ziegler, Johannes; Fischer, Ralf, 1965-; Savchenko, M. L.; Kvon, Z.D.; Mikhailov, N. N.; Dvoretsky, S. A.; Weiss, Dieter

    2016-01-01

    We measure the quantum capacitance and probe thus directly the electronic density of states of the high mobility, Dirac type of two-dimensional electron system, which forms on the surface of strained HgTe. Here we show that observed magneto-capacitance oscillations probe, in contrast to magnetotransport, primarily the top surface. Capacitance measurements constitute thus a powerful tool to probe only one topological surface and to reconstruct its Landau level spectrum for different positions ...

  11. DEVELOPMENT OF ADAPTED CAPACITANCE MANOMETER FOR  THERMOSPHERIC APPLICATIONS

    OpenAIRE

    Orr, Cameron Scott

    2016-01-01

    An adapted capacitance manometer is a sensor composed of one fixed plate and one movable plate that is able to make accurate pressure measurements in a low pressure environment. Using detection circuitry, a change in capacitance between the two plates can be measured and correlated to a differential pressure. First, a high sensitivity manometer is produced that exhibits a measurable change in capacitance when experiencing a pressure differential in a low pressure space environment. Second,...

  12. Static and Motional Feedthrough Capacitance of Flexural Microresonator

    OpenAIRE

    Wen-Teng Chang

    2011-01-01

    The present paper evaluates the static and motional feedthrough capacitance of a silicon carbide-based flexural-mode microelectromechanical system resonator. The static feedthrough capacitance was measured by a network analyzer under atmospheric pressure. The motional feedthrough was obtained by introducing various values into the modeling circuit in order to fit the Bode plots measured under reduced pressure. The static feedthrough capacitance was 0.02 pF, whereas the motional feedthrough ca...

  13. Capacitive position measurement for high-precision space inertial sensor

    Institute of Scientific and Technical Information of China (English)

    Yan-zheng BAI; Ze-bing ZHOU; Hai-bo TU; Shu-chao WU; Lin CAI; LI LIU; Jun LUO

    2009-01-01

    Low noise position measurement is fundamental for space inertial sensors, and at present the capacitive position sensor is widely employed for space inertial sensors. The design for the possible suppression of the front-end electric noises for a capacitive sensor is presented. A prototype capacitive sensor with 2x 10-6pF/Hzi/2 at frequency above 0.04 Hz is achieved and further improvements are discussed.

  14. Carrier Statistics and Quantum Capacitance Models of Graphene Nanoscroll

    Directory of Open Access Journals (Sweden)

    M. Khaledian

    2014-01-01

    schematic perfect scroll-like Archimedes spiral. The DOS model was derived at first, while it was later applied to compute the carrier concentration and quantum capacitance model. Furthermore, the carrier concentration and quantum capacitance were modeled for both degenerate and nondegenerate regimes, along with examining the effect of structural parameters and chirality number on the density of state and carrier concentration. Latterly, the temperature effect on the quantum capacitance was studied too.

  15. CMOS MEMS capacitive absolute pressure sensor

    International Nuclear Information System (INIS)

    This paper presents the design, fabrication and characterization of a capacitive pressure sensor using a commercial 0.18 µm CMOS (complementary metal–oxide–semiconductor) process and postprocess. The pressure sensor is capacitive and the structure is formed by an Al top electrode enclosed in a suspended SiO2 membrane, which acts as a movable electrode against a bottom or stationary Al electrode fixed on the SiO2 substrate. Both the movable and fixed electrodes form a variable parallel plate capacitor, whose capacitance varies with the applied pressure on the surface. In order to release the membranes the CMOS layers need to be applied postprocess and this mainly consists of four steps: (1) deposition and patterning of PECVD (plasma-enhanced chemical vapor deposition) oxide to protect CMOS pads and to open the pressure sensor top surface, (2) etching of the sacrificial layer to release the suspended membrane, (3) deposition of PECVD oxide to seal the etching holes and creating vacuum inside the gap, and finally (4) etching of the passivation oxide to open the pads and allow electrical connections. This sensor design and fabrication is suitable to obey the design rules of a CMOS foundry and since it only uses low-temperature processes, it allows monolithic integration with other types of CMOS compatible sensors and IC (integrated circuit) interface on a single chip. Experimental results showed that the pressure sensor has a highly linear sensitivity of 0.14 fF kPa−1 in the pressure range of 0–300 kPa. (paper)

  16. CMOS MEMS capacitive absolute pressure sensor

    Science.gov (United States)

    Narducci, M.; Yu-Chia, L.; Fang, W.; Tsai, J.

    2013-05-01

    This paper presents the design, fabrication and characterization of a capacitive pressure sensor using a commercial 0.18 µm CMOS (complementary metal-oxide-semiconductor) process and postprocess. The pressure sensor is capacitive and the structure is formed by an Al top electrode enclosed in a suspended SiO2 membrane, which acts as a movable electrode against a bottom or stationary Al electrode fixed on the SiO2 substrate. Both the movable and fixed electrodes form a variable parallel plate capacitor, whose capacitance varies with the applied pressure on the surface. In order to release the membranes the CMOS layers need to be applied postprocess and this mainly consists of four steps: (1) deposition and patterning of PECVD (plasma-enhanced chemical vapor deposition) oxide to protect CMOS pads and to open the pressure sensor top surface, (2) etching of the sacrificial layer to release the suspended membrane, (3) deposition of PECVD oxide to seal the etching holes and creating vacuum inside the gap, and finally (4) etching of the passivation oxide to open the pads and allow electrical connections. This sensor design and fabrication is suitable to obey the design rules of a CMOS foundry and since it only uses low-temperature processes, it allows monolithic integration with other types of CMOS compatible sensors and IC (integrated circuit) interface on a single chip. Experimental results showed that the pressure sensor has a highly linear sensitivity of 0.14 fF kPa-1 in the pressure range of 0-300 kPa.

  17. Developmental control of cell division

    NARCIS (Netherlands)

    Boxem, M. (Mike)

    2002-01-01

    During development of multicellular organisms, cell divisions need to be coordinated with the developmental program of the entire organism. Although the mechanisms that drive cells through the division cycle are well understood, very little is known about the pathways that link extracellular signals

  18. Lightning Talks 2015: Theoretical Division

    Energy Technology Data Exchange (ETDEWEB)

    Shlachter, Jack S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-25

    This document is a compilation of slides from a number of student presentations given to LANL Theoretical Division members. The subjects cover the range of activities of the Division, including plasma physics, environmental issues, materials research, bacterial resistance to antibiotics, and computational methods.

  19. 75 FR 70031 - Antitrust Division

    Science.gov (United States)

    2010-11-16

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Antitrust Division Notice Pursuant to the National Cooperative Research and Production Act of 1993--Open.... Brink, Deputy Director of Operations, Antitrust Division. BILLING CODE 4410-11-M...

  20. 78 FR 17431 - Antitrust Division

    Science.gov (United States)

    2013-03-21

    ... January 2, 2013 (78 FR 117). Patricia A. Brink, Director of Civil Enforcement, Antitrust Division. BILLING...) of the Act on July 30, 2001 (66 FR 39336). The last notification was filed with the Department on... Antitrust Division Notice Pursuant to the National Cooperative Research and Production Act of...

  1. 77 FR 54611 - Antitrust Division

    Science.gov (United States)

    2012-09-05

    ... on June 8, 2012 (77 FR 34067). Patricia A. Brink, Director of Civil Enforcement, Antitrust Division... Section 6(b) of the Act on June 30, 2000 (65 FR 40693). The last notification was filed with the... Antitrust Division Notice Pursuant to the National Cooperative Research and Production Act of...

  2. Division of Analytical Chemistry, 1998

    DEFF Research Database (Denmark)

    Hansen, Elo Harald

    1999-01-01

    The article recounts the 1998 activities of the Division of Analytical Chemistry (DAC- formerly the Working Party on Analytical Chemistry, WPAC), which body is a division of the Federation of European Chemical Societies (FECS). Elo Harald Hansen is the Danish delegate, representing The Danish...... Chemical Society/The Society for Analytical Chemistry....

  3. Important projects of the Division

    International Nuclear Information System (INIS)

    In this chapter important projects of the Division for Radiation Safety, NPP Decommissioning and Radwaste Management of the VUJE, a. s. are presented. Division for Radiation Safety, NPP Decommissioning and Radwaste Management has successfully carried out variety of significant projects. The most significant projects that were realised, are implemented and possible future projects are introduced in the following part of presentation.

  4. E-Division activities report

    International Nuclear Information System (INIS)

    This report describes some of the activities in E (Experimental Physics) Division during the past year. E-Division carries out research and development in areas related to the missions of the Laboratory. Many of the activities are in pure and applied atomic and nuclear physics. In addition, this report describes work on accelerators, radiation damage, microwaves, and plasma diagnostics

  5. Inversive meadows and divisive meadows

    NARCIS (Netherlands)

    J.A. Bergstra; C.A. Middelburg

    2011-01-01

    Inversive meadows are commutative rings with a multiplicative identity element and a total multiplicative inverse operation satisfying 0−1=0. Divisive meadows are inversive meadows with the multiplicative inverse operation replaced by a division operation. We give finite equational specifications of

  6. Negative capacitance and instability at electrified interfaces: Lessons from the study of membrane capacitors

    Directory of Open Access Journals (Sweden)

    M.B.Partenskii

    2005-01-01

    Full Text Available Various models leading to predictions of negative capacitance, C, are briefly reviewed. Their relation to the nature of electric control is discussed. We reconfirm that the calculated double layer capacitance can be negative under σ-control - an artificial construct that requires uniform distribution of the electrode surface charge density, σ. However, only the total charge C (or the average surface charge density can be experimentally fixed in isolated cell studies (q-control. For those σ where C becomes negative under σ-control, the transition to q-control (i.e. relaxing the lateral change density distribution, fixing its mean value to σ leads to instability of the uniform distribution and a transition to a non-uniform phase. As an illustration, a “membrane capacitor” model is discussed. This exactly solvable model, allowing for both uniform and inhomogeneous relaxation of the electrical double layer, helps to demonstrate both the onset and some important features of the instability. Possibilities for further development are discussed briefly.

  7. Capacitive tool standoff sensor for dismantlement tasks

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, D.J.; Weber, T.M. [Sandia National Labs., Albuquerque, NM (United States); Liu, J.C. [Univ. of Illinois, Urbana, IL (United States)

    1996-12-31

    A capacitive sensing technology has been applied to develop a Standoff Sensor System for control of robotically deployed tools utilized in Decontamination and Dismantlement (D and D) activities. The system combines four individual sensor elements to provide non-contact, multiple degree-of-freedom control of tools at distances up to five inches from a surface. The Standoff Sensor has been successfully integrated to a metal cutting router and a pyrometer, and utilized for real-time control of each of these tools. Experiments demonstrate that the system can locate stationary surfaces with a repeatability of 0.034 millimeters.

  8. Capacitive tool standoff sensor for dismantlement tasks

    International Nuclear Information System (INIS)

    A capacitive sensing technology has been applied to develop a Standoff Sensor System for control of robotically deployed tools utilized in Decontamination and Dismantlement (D and D) activities. The system combines four individual sensor elements to provide non-contact, multiple degree-of-freedom control of tools at distances up to five inches from a surface. The Standoff Sensor has been successfully integrated to a metal cutting router and a pyrometer, and utilized for real-time control of each of these tools. Experiments demonstrate that the system can locate stationary surfaces with a repeatability of 0.034 millimeters

  9. 3-D capacitance density imaging system

    Science.gov (United States)

    Fasching, G.E.

    1988-03-18

    A three-dimensional capacitance density imaging of a gasified bed or the like in a containment vessel is achieved using a plurality of electrodes provided circumferentially about the bed in levels and along the bed in channels. The electrodes are individually and selectively excited electrically at each level to produce a plurality of current flux field patterns generated in the bed at each level. The current flux field patterns are suitably sensed and a density pattern of the bed at each level determined. By combining the determined density patterns at each level, a three-dimensional density image of the bed is achieved. 7 figs.

  10. Calibration of capacitive hydrostatic leveling sensors of NSRL

    International Nuclear Information System (INIS)

    The principle of capacitive hydrostatic leveling sensors was presented. Simulations of sensors with two kinds of materials (metal and distilled water) as target electrode in the situations of calibration and work were carried out by Ansoft Maxwell software. Different values of capacitances in different situations were compared and analyzed. Then some experiments were done with independently developed prototype of capacitive hydrostatic leveling sensors to verify the above simulations. In the situations of calibration and work, the same property (conductivity and dielectric constant) material as target electrode should be chosen for capacitive hydrostatic leveling sensors. Otherwise, there is an error of sensors after calibration, and the main factor is conductivity. (authors)

  11. Variable-capacitance tachometer eliminates troublesome magnetic fields

    Science.gov (United States)

    1966-01-01

    Dual variable-capacitance tachometer measures angular speed and sense of rotation without magnetic components. Thus it eliminates magnetic flux interference with associated instrumentation in an electromechanical system.

  12. Individual and competitive removal of heavy metals using capacitive deionization.

    Science.gov (United States)

    Huang, Zhe; Lu, Lu; Cai, Zhenxiao; Ren, Zhiyong Jason

    2016-01-25

    This study presents the viability and preference of capacitive deionization (CDI) for removing different heavy metal ions in various conditions. The removal performance and mechanisms of three ions, cadmium (Cd(2+)), lead (Pb(2+)) and chromium (Cr(3+)) were investigated individually and as a mixture under different applied voltages and ion concentrations. It was found that CDI could effectively remove these metals, and the performance was positively correlated with the applied voltage. When 1.2 V was applied into solution containing 0.5mM individual ions, the Cd(2+), Pb(2+), and Cr(3+) removal was 32%, 43%, and 52%, respectively, and the electrosorption played a bigger role in Cd(2+) removal than for the other two ions. Interestingly, while the removal of Pb(2+) and Cr(3+) remained at a similar level of 46% in the mixture of three ions, the Cd(2+) removal significantly decreased to 14%. Similar patterns were observed when 0.05 mM was used to simulate natural contaminated water condition, but the removal efficiencies were much higher, with the removal of Pb(2+), Cr(3+), and Cd(2+) increased to 81%, 78%, and 42%, respectively. The low valence charge and lack of physical sorption of Cd(2+) were believed to be the reason for the removal behavior, and advanced microscopic analysis showed clear deposits of metal ions on the cathode surface after operation. PMID:26476320

  13. The feasibility of boron removal from water by capacitive deionization

    Energy Technology Data Exchange (ETDEWEB)

    Avraham, Eran, E-mail: eranchem@gmail.com [Department of Chemistry, Bar Ilan University, Ramat-Gan 52900 (Israel); Noked, Malachi; Soffer, Abraham; Aurbach, Doron [Department of Chemistry, Bar Ilan University, Ramat-Gan 52900 (Israel)

    2011-07-15

    Highlights: > Boron removal by electrochemical means. > Temporary local pH changes developed within the pores were indicated by using MgCl{sub 2} in the solution as a probe. > The process of Boron extraction from water takes place in two stages: 1. dissociation of boric acid on the negatively polarized electrode. 2. Electro-adsorption of borate ion onto the positively polarized electrode. - Abstract: We report on the possibility of removing boron (in the form of boric acid) from water by electrochemical means. We explore capacitive de-ionization (CDI) processes in which local changes in pH near the surface of high-surface-area activated carbon fiber (ACF) electrodes during charging are utilized, in order to dissociate boric acid into borate ions which can be electro-adsorbed onto the positive electrode in the CDI cells. For this purpose, a special flow-through CDI cell was constructed in which the feed solution flows through the electrodes. Local pH changes near the carbon electrode surface were investigated using a MgCl{sub 2} solution probe in three- (with reference) and two-electrode cells, and described qualitatively. We show that, to a certain extent, boron can indeed be removed from water by CDI.

  14. Capacitively coupled hybrid pixel assemblies for the CLIC vertex detector

    Science.gov (United States)

    Tehrani, N. Alipour; Arfaoui, S.; Benoit, M.; Dannheim, D.; Dette, K.; Hynds, D.; Kulis, S.; Perić, I.; Petrič, M.; Redford, S.; Sicking, E.; Valerio, P.

    2016-07-01

    The vertex detector at the proposed CLIC multi-TeV linear e+e- collider must have minimal material content and high spatial resolution, combined with accurate time-stamping to cope with the expected high rate of beam-induced backgrounds. One of the options being considered is the use of active sensors implemented in a commercial high-voltage CMOS process, capacitively coupled to hybrid pixel ASICs. A prototype of such an assembly, using two custom designed chips (CCPDv3 as active sensor glued to a CLICpix readout chip), has been characterised both in the lab and in beam tests at the CERN SPS using 120 GeV/c positively charged hadrons. Results of these characterisation studies are presented both for single and dual amplification stages in the active sensor, where efficiencies of greater than 99% have been achieved at -60 V substrate bias, with a single hit resolution of 6.1 μm . Pixel cross-coupling results are also presented, showing the sensitivity to placement precision and planarity of the glue layer.

  15. Individual and competitive removal of heavy metals using capacitive deionization.

    Science.gov (United States)

    Huang, Zhe; Lu, Lu; Cai, Zhenxiao; Ren, Zhiyong Jason

    2016-01-25

    This study presents the viability and preference of capacitive deionization (CDI) for removing different heavy metal ions in various conditions. The removal performance and mechanisms of three ions, cadmium (Cd(2+)), lead (Pb(2+)) and chromium (Cr(3+)) were investigated individually and as a mixture under different applied voltages and ion concentrations. It was found that CDI could effectively remove these metals, and the performance was positively correlated with the applied voltage. When 1.2 V was applied into solution containing 0.5mM individual ions, the Cd(2+), Pb(2+), and Cr(3+) removal was 32%, 43%, and 52%, respectively, and the electrosorption played a bigger role in Cd(2+) removal than for the other two ions. Interestingly, while the removal of Pb(2+) and Cr(3+) remained at a similar level of 46% in the mixture of three ions, the Cd(2+) removal significantly decreased to 14%. Similar patterns were observed when 0.05 mM was used to simulate natural contaminated water condition, but the removal efficiencies were much higher, with the removal of Pb(2+), Cr(3+), and Cd(2+) increased to 81%, 78%, and 42%, respectively. The low valence charge and lack of physical sorption of Cd(2+) were believed to be the reason for the removal behavior, and advanced microscopic analysis showed clear deposits of metal ions on the cathode surface after operation.

  16. Physics Division computer facilities

    Energy Technology Data Exchange (ETDEWEB)

    Cyborski, D.R.; Teh, K.M.

    1995-08-01

    The Physics Division maintains several computer systems for data analysis, general-purpose computing, and word processing. While the VMS VAX clusters are still used, this past year saw a greater shift to the Unix Cluster with the addition of more RISC-based Unix workstations. The main Divisional VAX cluster which consists of two VAX 3300s configured as a dual-host system serves as boot nodes and disk servers to seven other satellite nodes consisting of two VAXstation 3200s, three VAXstation 3100 machines, a VAX-11/750, and a MicroVAX II. There are three 6250/1600 bpi 9-track tape drives, six 8-mm tapes and about 9.1 GB of disk storage served to the cluster by the various satellites. Also, two of the satellites (the MicroVAX and VAX-11/750) have DAPHNE front-end interfaces for data acquisition. Since the tape drives are accessible cluster-wide via a software package, they are, in addition to replay, used for tape-to-tape copies. There is however, a satellite node outfitted with two 8 mm drives available for this purpose. Although not part of the main cluster, a DEC 3000 Alpha machine obtained for data acquisition is also available for data replay. In one case, users reported a performance increase by a factor of 10 when using this machine.

  17. Hole emission from Ge/Si quantum dots studied by time-resolved capacitance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kapteyn, C.M.A.; Lion, M.; Heitz, R.; Bimberg, D. [Technische Univ. Berlin (Germany). Inst. fuer Festkoerperphysik; Miesner, C.; Asperger, T.; Brunner, K.; Abstreiter, G. [Technische Univ. Muenchen, Garching (Germany). Walter-Schottky-Inst. fuer Physikalische Grundlagen der Halbleiterelektronik

    2001-03-01

    Emission of holes from self-organized Ge quantum dots (QDs) embedded in Si Schottky diodes is studied by time-resolved capacitance spectroscopy (DLTS). The DLTS signal is rather broad and depends strongly on the filling and detection bias conditions. The observed dependence is interpreted in terms of carrier emission from many-hole states of the QDs. The activation energies obtained from the DLTS measurements are a function of the amount of stored charge and the position of the Fermi level in the QDs. (orig.)

  18. Particle-in-Cell/Test-Particle Simulations of Technological Plasmas: Sputtering Transport in Capacitive Radio Frequency Discharges

    OpenAIRE

    Trieschmann, Jan; Schmidt, Frederik; Mussenbrock, Thomas

    2016-01-01

    The paper provides a tutorial to the conceptual layout of a self-consistently coupled Particle-In-Cell/Test-Particle model for the kinetic simulation of sputtering transport in capacitively coupled plasmas at low gas pressures. It explains when a kinetic approach is actually needed and which numerical concepts allow for the inherent nonequilibrium behavior of the charged and neutral particles. At the example of a generic sputtering discharge both the fundamentals of the applied Monte Carlo me...

  19. A new benchmark capacitance for supercapacitor anodes by mixed-valence sulfur-doped V6O(13-x).

    Science.gov (United States)

    Zhai, Teng; Lu, Xihong; Ling, Yichuan; Yu, Minghao; Wang, Gongming; Liu, Tianyu; Liang, Chaolun; Tong, Yexiang; Li, Yat

    2014-09-01

    A new pseudocapacitor anode, sulfur-doped V6O(13-x), is reported. It achieves a benchmark capacitance of 1353 F/g (0.72 F/cm(2)) at a current density of 1.9 A/g (1 mA/cm(2)) in 5 M LiCl solution. The charges are stored chemically in the electrode via reversible redox reactions that involve multiple oxidation states of vanadium (V(3+), V(4+) and V(5+)). PMID:25080307

  20. Differential capacitance of the electric double layer: the interplay between ion finite size and dielectric decrement.

    Science.gov (United States)

    Nakayama, Yasuya; Andelman, David

    2015-01-28

    We study the electric double layer by combining the effects of ion finite size and dielectric decrement. At high surface potential, both mechanisms can cause saturation of the counter-ion concentration near a charged surface. The modified Grahame equation and differential capacitance are derived analytically for a general expression of a permittivity ε(n) that depends on the local ion concentration, n, and under the assumption that the co-ions are fully depleted from the surface. The concentration at counter-ion saturation is found for any ε(n), and a criterion predicting which of the two mechanisms (steric vs. dielectric decrement) is the dominant one is obtained. At low salinity, the differential capacitance as function of surface potential has two peaks (so-called camel-shape). Each of these two peaks is connected to a saturation of counter-ion concentration caused either by dielectric decrement or by their finite size. Because these effects depend mainly on the counter-ion concentration at the surface proximity, for opposite surface-potential polarity either the cations or anions play the role of counter-ions, resulting in an asymmetric camel-shape. At high salinity, we obtain and analyze the crossover in the differential capacitance from a double-peak shape to a uni-modal one. Finally, several nonlinear models of the permittivity decrement are considered, and we predict that the concentration at dielectrophoretic saturation shifts to higher concentration than those obtained by the linear decrement model. PMID:25638002

  1. Studying tantalum-based high-κ dielectrics in terms of capacitance measurements

    Science.gov (United States)

    Stojanovska-Georgievska, L.

    2016-08-01

    The trend of rapid development of microelectronics towards nano-miniaturization dictates the inevitable introduction of dielectrics with high permittivity (high-κ dielectrics), as alternative material for replacing SiO2. Therefore, studying these materials in terms of their characteristics, especially in terms of reliability, is of great importance for proper design and manufacture of devices. In this paper, alteration of capacitance in different frequency regimes is used, in order to determine the overall behavior of the material. Samples investigated here are MOS structures containing nanoscale tantalum based dielectrics. Layers of pure Ta2O5, but also Hf and Ti doped tantalum pentoxide, i.e. Ta2O5:Hf and Ta2O5:Ti are studied here. All samples are considered as ultrathin oxide layers with thicknesses less than 15 nm, obtained by radio frequent sputtering on p-type silicon substrate. Measuring capacitive characteristics enables determination of several specific parameters of the structures. The obtained results for capacitance in accumulation, the thickness and time evolution of the interfacial SiO2 layer, values of flatband and threshold voltage, density of oxide charges, interfacial and border states, and reliability properties favor the possibilities for more intensive use of studied materials in new nanoelectronic technologies.

  2. An associative capacitive network based on nanoscale complementary resistive switches for memory-intensive computing

    Science.gov (United States)

    Kavehei, Omid; Linn, Eike; Nielen, Lutz; Tappertzhofen, Stefan; Skafidas, Efstratios; Valov, Ilia; Waser, Rainer

    2013-05-01

    We report on the implementation of an Associative Capacitive Network (ACN) based on the nondestructive capacitive readout of two Complementary Resistive Switches (2-CRSs). ACNs are capable of performing a fully parallel search for Hamming distances (i.e. similarity) between input and stored templates. Unlike conventional associative memories where charge retention is a key function and hence, they require frequent refresh cycles, in ACNs, information is retained in a nonvolatile resistive state and normal tasks are carried out through capacitive coupling between input and output nodes. Each device consists of two CRS cells and no selective element is needed, therefore, CMOS circuitry is only required in the periphery, for addressing and read-out. Highly parallel processing, nonvolatility, wide interconnectivity and low-energy consumption are significant advantages of ACNs over conventional and emerging associative memories. These characteristics make ACNs one of the promising candidates for applications in memory-intensive and cognitive computing, switches and routers as binary and ternary Content Addressable Memories (CAMs) and intelligent data processing.

  3. Nickel Nanofoam/Different Phases of Ordered Mesoporous Carbon Composite Electrodes for Superior Capacitive Energy Storage.

    Science.gov (United States)

    Lee, Kangsuk; Song, Haeni; Lee, Kwang Hoon; Choi, Soo Hyung; Jang, Jong Hyun; Char, Kookheon; Son, Jeong Gon

    2016-08-31

    Electrochemical energy storage devices based on electric double layer capacitors (EDLCs) have received considerable attention due to their high power density and potential for obtaining improved energy density in comparison to the lithium ion battery. Ordered mesoporous carbon (OMC) is a promising candidate for use as an EDLC electrode because it has a high specific surface area (SSA), providing a wider charge storage space and size-controllable mesopore structure with a long-range order, suppling high accessibility to the electrolyte ions. However, OMCs fabricated using conventional methods have several drawbacks including low electronic conductivity and long ionic diffusion paths in mesopores. We used nickel nanofoam, which has a relatively small pore (sub-100 nm to subμm) network structure, as a current collector. This provides a significantly shortened electronic/ionic current paths and plentiful surface area, enabling stable and close attachment of OMCs without the use of binders. Thus, we present hierarchical binder-free electrode structures based on OMC/Ni nanofoams. These structures give rise to enhanced specific capacitance and a superior rate capability. We also investigated the mesopore structural effect of OMCs on electrolyte transport by comparing the capacitive performances of collapsed lamellar, cylindrical, and spherical mesopore electrodes. The highly ordered and straightly aligned cylindrical OMCs exhibited the highest specific capacitance and the best rate capability. PMID:27490161

  4. High performance super-capacitive behaviour of deposited manganese oxide/nickel oxide binary electrode system

    International Nuclear Information System (INIS)

    The chrono-potentiometry technique was used to deposit MnO2-NiO binary metal oxide film on a stainless steel substrate at room temperature. During the electrodeposition process, the concentration of nickel acetate is varied in the fixed 0.01 M manganese acetate solution. The products were characterised by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscopy (FESEM). Their capacitive behaviour was studied by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy in two different alkaline electrolytes using a three electrode set-up. The MnO2-NiO binary metal oxide electrode deposited from Ni(CH3COO)2.4H2O:Mn(CH3COO)2.4H2O at a molar ratio of 0.25:0.01 (molar:molar) was found to be the best electrode with the lowest transfer resistance based on the Nyquist plots. The specific capacitance of the best electrode, NiO-25, exhibited a specific capacitance of 435 Fg−1 and 681 Fg−1 with an energy density of 242 Whkg−1 and 213 Whkg−1 in 0.5 M Na2SO4 and 0.5 M KOH electrolyte, respectively

  5. In-situ polymerization of polyaniline on the surface of graphene oxide for high electrochemical capacitance

    International Nuclear Information System (INIS)

    Conducting polymer polyaniline (PANI) was in-situ polymerized on the surface of graphene oxide (GO) to form PANI encapsulating GO nanocomposites. The morphology and microstructure were examined by scanning electron microscopy, X-ray diffraction and N2 absorption/desorption analysis. Electrochemical properties were tested by cyclic voltammetry, galvanostatic charge/discharge cycles and electrochemical impedance spectroscopy. Experimental results showed that ethanol assisted the dispersion of GO in water and facilitated the diffusion of polymer monomers on GO. GO as a support material can provide sufficient reaction sites for the deposition of aniline to form the film-like GO/PANI composites. Capacitive performance illustrated that the in-situ polymerization of PANI on GO was effective in improving the specific capacitance and cycling stability. - Highlights: • GO/PANI nanocomposites were achieved by in-situ polymerization. • PANI was uniformly coated on the surface of GO with addition of ethanol. • GO/PANI show high specific capacitance and cycling stability

  6. Effect of Ni-doping on electrochemical capacitance of MnO2 electrode materials

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Mn/Ni composite oxides as active electrode materials for supercapacitors were prepared by solid-state reaction through the reduction of KMnO4 with manganese acetate and nickel acetate at low temperature. The products were characterized by X-ray dirrractometry(XRD) and transmission electron microscopy(TEM). The electrochemical characterizations were performed by cyclic voltammetry (CV) and constant current charge-discharge in a three-electrode system. The effects of different potential windows, scan rates, and cycle numbers on the capacitance behavior of Mn0.gNi0.2Ox composite oxide were also investigated. The results show that the composite oxides are of nano-size and amorphous structure. With increasing the molar ratio of Ni, the specific capacitance goes through a maximum at molar fraction of Ni of 20%. The specific capacitance of Mn0.8Ni0.2Ox composite oxide is 194.5 F/g at constant current discharge of 5 mA.

  7. In-situ polymerization of polyaniline on the surface of graphene oxide for high electrochemical capacitance

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xinlu, E-mail: lixinlu@cqu.edu.cn; Zhong, Qineng; Zhang, Xinlin; Li, Tongtao; Huang, Jiamu

    2015-06-01

    Conducting polymer polyaniline (PANI) was in-situ polymerized on the surface of graphene oxide (GO) to form PANI encapsulating GO nanocomposites. The morphology and microstructure were examined by scanning electron microscopy, X-ray diffraction and N{sub 2} absorption/desorption analysis. Electrochemical properties were tested by cyclic voltammetry, galvanostatic charge/discharge cycles and electrochemical impedance spectroscopy. Experimental results showed that ethanol assisted the dispersion of GO in water and facilitated the diffusion of polymer monomers on GO. GO as a support material can provide sufficient reaction sites for the deposition of aniline to form the film-like GO/PANI composites. Capacitive performance illustrated that the in-situ polymerization of PANI on GO was effective in improving the specific capacitance and cycling stability. - Highlights: • GO/PANI nanocomposites were achieved by in-situ polymerization. • PANI was uniformly coated on the surface of GO with addition of ethanol. • GO/PANI show high specific capacitance and cycling stability.

  8. Physics division annual report 1999

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, K., ed.; Physics

    2000-12-06

    This report summarizes the research performed in the past year in the Argonne Physics Division. The Division's programs include operation of ATLAS as a national heavy-ion user facility, nuclear structure and reaction research with beams of heavy ions, accelerator research and development especially in superconducting radio frequency technology, nuclear theory and medium energy nuclear physics. The Division took significant strides forward in its science and its initiatives for the future in the past year. Major progress was made in developing the concept and the technology for the future advanced facility of beams of short-lived nuclei, the Rare Isotope Accelerator. The scientific program capitalized on important instrumentation initiatives with key advances in nuclear science. In 1999, the nuclear science community adopted the Argonne concept for a multi-beam superconducting linear accelerator driver as the design of choice for the next major facility in the field a Rare Isotope Accelerator (WA) as recommended by the Nuclear Science Advisory Committee's 1996 Long Range Plan. Argonne has made significant R&D progress on almost all aspects of the design concept including the fast gas catcher (to allow fast fragmentation beams to be stopped and reaccelerated) that in large part defined the RIA concept the superconducting rf technology for the driver accelerator, the multiple-charge-state concept (to permit the facility to meet the design intensity goals with existing ion-source technology), and designs and tests of high-power target concepts to effectively deal with the full beam power of the driver linac. An NSAC subcommittee recommended the Argonne concept and set as tie design goal Uranium beams of 100-kwatt power at 400 MeV/u. Argonne demonstrated that this goal can be met with an innovative, but technically in-hand, design. The heavy-ion research program focused on GammaSphere, the premier facility for nuclear structure gamma-ray studies. One example

  9. Circuital characterisation of space-charge motion with a time-varying applied bias

    Science.gov (United States)

    Kim, Chul; Moon, Eun-Yi; Hwang, Jungho; Hong, Hiki

    2015-07-01

    Understanding the behaviour of space-charge between two electrodes is important for a number of applications. The Shockley-Ramo theorem and equivalent circuit models are useful for this; however, fundamental questions of the microscopic nature of the space-charge remain, including the meaning of capacitance and its evolution into a bulk property. Here we show that the microscopic details of the space-charge in terms of resistance and capacitance evolve in a parallel topology to give the macroscopic behaviour via a charge-based circuit or electric-field-based circuit. We describe two approaches to this problem, both of which are based on energy conservation: the energy-to-current transformation rule, and an energy-equivalence-based definition of capacitance. We identify a significant capacitive current due to the rate of change of the capacitance. Further analysis shows that Shockley-Ramo theorem does not apply with a time-varying applied bias, and an additional electric-field-based current is identified to describe the resulting motion of the space-charge. Our results and approach provide a facile platform for a comprehensive understanding of the behaviour of space-charge between electrodes.

  10. Nanostructured conducting polymer based reagentless capacitive immunosensor.

    Science.gov (United States)

    Bandodkar, Amay Jairaj; Dhand, Chetna; Arya, Sunil K; Pandey, M K; Malhotra, Bansi D

    2010-02-01

    Nanostructured polyaniline (PANI) film electrophoretically fabricated onto indium-tin-oxide (ITO) coated glass plate has been utilized for development of an immunosensor based on capacitance change of a parallel plate capacitor (PPC) by covalently immobilizing anti-human IgG (Anti-HIgG) using N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide chemistry. These fabricated PANI/ITO and Anti-HIgG/PANI/ITO plates have been characterized using scanning electron microscopy, cyclic voltammetry, differential pulse voltammetry and Fourier transform infra-red studies. The capacitance measurements indicate that dielectric medium of this biologically modified PPC (Anti-HIgG/PANI/ITO) is sensitive to HIgG in 5 - 5 x 10(5) ng mL(-1) range and has lower detection limit of 1.87 ng mL(-1). The observed results reveal that this Anti-HIgG modified PPC can be used as a robust, easy-to-use, reagentless, sensitive and selective immunosensor for estimation of human IgG.

  11. THERMAL DRIFT CHARACTERISTICS OF CAPACITIVE PRESSURE SENSORS

    Directory of Open Access Journals (Sweden)

    ABDELAZIZ BEDDIAF

    2016-03-01

    Full Text Available The capacitive pressure sensors based on silicon are characterized by their very high sensitivities and their low power consumption. Nevertheless, their thermal behavior remains more or less unpredictable because they can indicate very high thermal coefficients. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristics drift. In this study, we modeled the thermal behavior of this sensors, using Finite Element Analysis (FEA made in COMSOL. The model solved by COMSOL environment takes into account the entire sensor and thermal effects due to the temperature considering the materials’ properties, the geometric shape and also the heat transfer mechanisms. By COMSOL we determine how the temperature affects the sensor during the manufacturing process. For that end, we calculated the thermal drift of capacitance at rest, the thermal coefficients and we compared them with experimental results to validate our model. Further, we studied the thermal drift of sensor characteristics both at rest and under constant and uniform pressure. Further, our study put emphasis on the geometric influence parameters on these characteristics to optimize the sensor performance. Finally, this study allows us to predict the sensor behavior against temperature and to minimize this effect by optimizing the geometrical parameters.

  12. Impact of the Capacitance of the Dielectric on the Contact Resistance of Organic Thin-Film Transistors

    Science.gov (United States)

    Zojer, K.; Zojer, E.; Fernandez, A. F.; Gruber, M.

    2015-10-01

    As the operation of organic thin-film transistors relies exclusively on injected charge carriers, the gate-induced field assumes a dual role: It is responsible for charge-carrier accumulation and, provided that an injection barrier at the contact-semiconductor interface is present, aids charge-carrier injection across this barrier. Besides the gate-source bias, the thickness of the insulator and its dielectric constant influence the gate field. Here, we explore the impact of the capacitance of the gate dielectric on the performance of organic thin-film transistors utilizing drift-diffusion-based simulations comprising a self-consistent consideration of injection. Upon varying the capacitance of the insulating layer, we observe a conceptually different behavior for top-contact and bottom-contact architectures. Top-contact devices possess a nearly constant contact voltage in the linear regime leading to an apparent mobility lowering. In strong contrast, bottom-contact architectures possess non-Ohmic contact resistances in the linear regime due to a contact voltage whose value depends strongly on both the gate-source bias and the capacitance. Counterintuitively, this is accompanied by a mobility being apparently unaffected by the substantial contact resistance. Additionally, threshold-voltage shifts appear due to gate-limited injection. The latter is particularly dominant in bottom-contact architectures, where the threshold voltages steeply increase with the thickness of the insulating layer.

  13. Scientific Equipment Division - Overview

    International Nuclear Information System (INIS)

    Full text: The Scientific Equipment Division consists of the Design Group and the Mechanical Workshop. The activity of the Division includes the following: - designing of devices and equipment for experiments in physics, their mechanical construction and assembly. In particular, there are vacuum chambers and installations for HV and UHV; - maintenance and upgrading of the existing installations and equipment in our Institute; - participation of our engineers and technicians in design works, equipment assembly and maintenance for experiments in foreign laboratories. The Design Group is equipped with PC-computers and AutoCAD graphic software (release 2000 and Mechanical Desktop 4.0) and a AO plotter, what allows us to make drawings and 2- and 3-dimensional mechanical documentation to the world standards. The Mechanical Workshop can offer a wide range of machining and treatment methods with satisfactory tolerances and surface quality. It offers the following possibilities: - turning - cylindrical elements of a length up to 2000 mm and a diameter up to 400 mm, and also disc-type elements of a diameter up to 600 mm and a length not exceeding 300 mm; - milling - elements of length up to 1000 mm and gear wheels of diameter up to 300 mm; - grinding - flat surfaces of dimensions up to 300 mm x 1000 mm and cylindrical elements of a diameter up to 200 mm and a length up to 800 mm; - drilling - holes of a diameter up to 50 mm; - welding - electrical and gas welding, including TIG vacuum-tight welding; - soft and hard soldering; - mechanical works including precision engineering; - plastics treatment - machining and polishing using diamond milling, modelling, lamination of various shapes and materials, including plexiglas, scintillators and light-guides; - painting - paint spraying with possibility of using furnace-fred drier of internal dimensions of 800 mm x 800 mm x 800 mm. Our workshop posses CNC milling machine which can be used for machining of work-pieces up to 500 kg

  14. Preparation and capacitive properties of lithium manganese oxide intercalation compound

    International Nuclear Information System (INIS)

    Lithium manganese oxide intercalation compound (Li0.7MnO2) supported on titanium nitride nanotube array (TiN NTA) was applied as cathode electrode material for lithium-ion supercapacitor application. Li0.7MnO2/TiN NTA was fabricated through electrochemical deposition and simultaneous intercalation process using TiN NTA as a substrate, Mn(CH3COO)2 as manganese source, and Li2SO4 as lithium source. The morphology and microstructure of the Li0.7MnO2/TiN NTA were characterized by scanning electron microscopy and X-ray diffraction analysis. The electrochemical performance of the Li0.7MnO2/TiN NTA was investigated by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge measurements. Li0.7MnO2/TiN NTA exhibited higher capacitive performance in Li2SO4 electrolyte solution rather than that in Na2SO4 electrolyte solution, which was due to the different intercalation effects of lithium-ion and sodium-ion. The specific capacitance was improved from 503.3 F g−1 for MnO2/TiN NTA to 595.0 F g−1 for Li0.7MnO2/TiN NTA at a current density of 2 A g−1 in 1.0 M Li2SO4 electrolyte solution, which was due to the intercalation of lithium-ion for Li0.7MnO2. Li0.7MnO2/TiN NTA also kept 90.4 % capacity retention after 1000 cycles, presenting a good cycling stability. An all-solid-state lithium-ion supercapacitor was fabricated and showed an energy density of 82.5 Wh kg−1 and a power density of 10.0 kW kg−1

  15. Preparation and capacitive properties of lithium manganese oxide intercalation compound

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Fang; Xie, Yibing, E-mail: ybxie@seu.edu.cn [Southeast University, School of Chemistry and Chemical Engineering (China)

    2015-12-15

    Lithium manganese oxide intercalation compound (Li{sub 0.7}MnO{sub 2}) supported on titanium nitride nanotube array (TiN NTA) was applied as cathode electrode material for lithium-ion supercapacitor application. Li{sub 0.7}MnO{sub 2}/TiN NTA was fabricated through electrochemical deposition and simultaneous intercalation process using TiN NTA as a substrate, Mn(CH{sub 3}COO){sub 2} as manganese source, and Li{sub 2}SO{sub 4} as lithium source. The morphology and microstructure of the Li{sub 0.7}MnO{sub 2}/TiN NTA were characterized by scanning electron microscopy and X-ray diffraction analysis. The electrochemical performance of the Li{sub 0.7}MnO{sub 2}/TiN NTA was investigated by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge measurements. Li{sub 0.7}MnO{sub 2}/TiN NTA exhibited higher capacitive performance in Li{sub 2}SO{sub 4} electrolyte solution rather than that in Na{sub 2}SO{sub 4} electrolyte solution, which was due to the different intercalation effects of lithium-ion and sodium-ion. The specific capacitance was improved from 503.3 F g{sup −1} for MnO{sub 2}/TiN NTA to 595.0 F g{sup −1} for Li{sub 0.7}MnO{sub 2}/TiN NTA at a current density of 2 A g{sup −1} in 1.0 M Li{sub 2}SO{sub 4} electrolyte solution, which was due to the intercalation of lithium-ion for Li{sub 0.7}MnO{sub 2}. Li{sub 0.7}MnO{sub 2}/TiN NTA also kept 90.4 % capacity retention after 1000 cycles, presenting a good cycling stability. An all-solid-state lithium-ion supercapacitor was fabricated and showed an energy density of 82.5 Wh kg{sup −1} and a power density of 10.0 kW kg{sup −1}.

  16. Physics division annual report 2006.

    Energy Technology Data Exchange (ETDEWEB)

    Glover, J.; Physics

    2008-02-28

    This report highlights the activities of the Physics Division of Argonne National Laboratory in 2006. The Division's programs include the operation as a national user facility of ATLAS, the Argonne Tandem Linear Accelerator System, research in nuclear structure and reactions, nuclear astrophysics, nuclear theory, investigations in medium-energy nuclear physics as well as research and development in accelerator technology. The mission of nuclear physics is to understand the origin, evolution and structure of baryonic matter in the universe--the core of matter, the fuel of stars, and the basic constituent of life itself. The Division's research focuses on innovative new ways to address this mission.

  17. Physics division annual report 2006

    International Nuclear Information System (INIS)

    This report highlights the activities of the Physics Division of Argonne National Laboratory in 2006. The Division's programs include the operation as a national user facility of ATLAS, the Argonne Tandem Linear Accelerator System, research in nuclear structure and reactions, nuclear astrophysics, nuclear theory, investigations in medium-energy nuclear physics as well as research and development in accelerator technology. The mission of nuclear physics is to understand the origin, evolution and structure of baryonic matter in the universe--the core of matter, the fuel of stars, and the basic constituent of life itself. The Division's research focuses on innovative new ways to address this mission

  18. ftsZ gene and plastid division

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Plastid is one of the most important cellular organelles, the normal division process of plastid is essential for the differentiation and development of plant cells. For a long time, morphological observations and genetic analyses to special mutants are the major research fields of plastid division, but the molecular mechanisms underlying plastid division are largely unknown. Because of the endosymbiotic origin, plastid division might have mechanisms in common with those involved in bacterial cell division. It has been proved that several prokaryotic cell division genes also participate in the plastid division. Recently, the mechanisms of prokaryotic cell division have been well documented, which provides a valuable paradigm for understanding the plastid division mechanisms. In plants, the functional analyses of ftsZ, a key gene involved both in bacteria and plastid division, have established the solid foundation for people to understand the plastid division in molecular level. In this paper we will make a review for the research history and progress of plastid division.

  19. Clean energy generation using capacitive electrodes in reverse electrodialysis

    NARCIS (Netherlands)

    Vermaas, D.A.; Bajracharya, S.; Bastos Sales, B.; Saakes, Michel; Hamelers, B.; Nijmeijer, D.C.

    2013-01-01

    Capacitive reverse electrodialysis (CRED) is a newly proposed technology to generate electricity from mixing of salt water and fresh water (salinity gradient energy) by using a membrane pile as in reverse electrodialysis (RED) and capacitive electrodes. The salinity difference between salt water and

  20. Electric field theory and the fallacy of void capacitance

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    1991-01-01

    The concept of the capacitance of a gaseous void is discussed as applied to electrical insulation science. The most pertinent aspect of the capacitance definition is that of reference to a single-valued potential difference between surfaces. This implies that these surfaces must be surfaces...

  1. Polycrystalline VO2 film characterization by quantum capacitance measurement

    International Nuclear Information System (INIS)

    Capacitance measurement is performed using a home-built bridge on quasi two-dimensional vanadium dioxide films grown on silicon-dioxide/p-doped silicon substrates. Correlated effects appearing in the quantum capacitance are obtained as a function of temperature at low frequencies. The thermodynamic density of states reveals the opening band gap in the insulating monoclinic phase

  2. Traveling mirror compressor delay line with nonconstant capacitance

    OpenAIRE

    Bellan, P. M.

    1981-01-01

    The scaling relations for a traveling mirror magnetic compressor [P.M. Bellan, Phys. Rev. Lett. 43, 858 (1979)] having nonconstant capacitance are derived. Varying capacitance (rather than inductance) makes possible a lower impedance device, and hence, higher field levels or faster compression times.

  3. Capacitance tuning of nanoscale split-ring resonators

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Mortensen, Asger; Kristensen, Anders

    2009-01-01

    We investigate the capacitance tuning of nanoscale split-ring resonators. Based on a simple inductor-capacitor circuit model, we derive an expression, where the inductance is proportional to the area while the capacitance reflects the aspect ratio of the slit. The resonance frequency may thus...

  4. Capacitance tuning of nanoscale split-ring resonators

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Xiao, Sanshui; Mortensen, Niels Asger;

    2010-01-01

    In this paper, we investigate the capacitance tuning of nanoscale split-ring resonators. Based on a simple LC circuit model (LC-model), we derive an expression where the inductance is proportional to the area while the capacitance reflects the aspect ratio of the slit. The resonance frequency may...

  5. Analysis of polypyrrole-coated stainless steel electrodes - Estimation of specific capacitances and construction of equivalent circuits

    Indian Academy of Sciences (India)

    R Ramya; M V Sangaranarayanan

    2008-01-01

    The galvanostatic polymerization of pyrrole is carried out on stainless steel electrodes using -toluene sulphonic acid. The morphology of the film is studied from Scanning Electron Microscopy (SEM) measurements while the nature of the substrate is analysed using Energy Dispersive X-ray Spectroscopy (EDAX) technique. The electrochemical behaviour is studied using cyclic voltammetry, charge-discharge analysis and impedance spectroscopy. The feasibility of the electrode for supercapacitor applications is investigated. The specific capacitance is estimated as ∼ 102 Farads per gram with 103 charge-discharge cycles. A plausible equivalent circuit for the system is proposed and the circuit parameters are obtained by non-linear regression analysis.

  6. Study of High Capacitance Ratios CPW MEMS Shunt Switches

    Institute of Scientific and Technical Information of China (English)

    Jianhai Sun; Dafu Cui

    2006-01-01

    This paper describes a fixed-fixed beam ohmic switch in series with a fixed capacitor as a replacement for a capacitive switch. In this switch, a metal plate deposited on the dielectric ensures perfectly contact with the dielectric layer in the down state. The area size of the metal plate directly influences the capacitance ratio of the switch, as the area size of the metal cap decreases, the capacitance ratio dramatically rises up. The down/up capacitance ratio can exceed 800 times over the conventional designs using the same materials and the equal size. Measurement results show that high capacitance ratio of the switches has a large effect on the isolation, and can actually improve the performance of the switches.

  7. Electrostatic capacitance and Faraday cage behavior of carbon nanotube forests

    Energy Technology Data Exchange (ETDEWEB)

    Ya' akobovitz, A. [Mechanosynthesis Group, Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Department of Mechanical Engineering, Faculty of Engineering Sciences, Ben-Gurion University, Beer-Sheva (Israel); Bedewy, M. [Mechanosynthesis Group, Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Hart, A. J. [Mechanosynthesis Group, Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Department of Mechanical Engineering and Laboratory for Manufacturing and Productivity, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-02-02

    Understanding of the electrostatic properties of carbon nanotube (CNT) forests is essential to enable their integration in microelectronic and micromechanical devices. In this study, we sought to understand how the hierarchical geometry and morphology of CNT forests determines their capacitance. First, we find that at small gaps, solid micropillars have greater capacitance, yet at larger gaps the capacitance of the CNT forests is greater. The surface area of the CNT forest accessible to the electrostatic field was extracted by analysis of the measured capacitance, and, by relating the capacitance to the average density of CNTs in the forest, we find that the penetration depth of the electrostatic field is on the order of several microns. Therefore, CNT forests can behave as a miniature Faraday cage. The unique electrostatic properties of CNT forests could therefore enable their use as long-range proximity sensors and as shielding elements for miniature electronic devices.

  8. Electrostatic capacitance and Faraday cage behavior of carbon nanotube forests

    International Nuclear Information System (INIS)

    Understanding of the electrostatic properties of carbon nanotube (CNT) forests is essential to enable their integration in microelectronic and micromechanical devices. In this study, we sought to understand how the hierarchical geometry and morphology of CNT forests determines their capacitance. First, we find that at small gaps, solid micropillars have greater capacitance, yet at larger gaps the capacitance of the CNT forests is greater. The surface area of the CNT forest accessible to the electrostatic field was extracted by analysis of the measured capacitance, and, by relating the capacitance to the average density of CNTs in the forest, we find that the penetration depth of the electrostatic field is on the order of several microns. Therefore, CNT forests can behave as a miniature Faraday cage. The unique electrostatic properties of CNT forests could therefore enable their use as long-range proximity sensors and as shielding elements for miniature electronic devices

  9. Study of CMOS integrated signal processing circuit in capacitive sensors

    Institute of Scientific and Technical Information of China (English)

    CAO Yi-jiang; YU Xiang; WANG Lei

    2007-01-01

    A CMOS integrated signal processing circuit based on capacitance resonance principle whose structure is simple in capacitive sensors is designed. The waveform of output voltage is improved by choosing bootstrap reference current mirror with initiate circuit, CMOS analogy switch and positive feedback of double-stage inverter in the circuit. Output voltage of this circuit is a symmetric square wave signal. The variation of sensitive capacitance, which is part of the capacitive sensors, can be denoted by the change of output voltage's frequency. The whole circuit is designed with 1.5 μm P-well CMOS process and simulated by PSpice software.Output frequency varies from 261.05 kHz to 47.93 kHz if capacitance varies in the range of 1PF~15PF. And the variation of frequency can be easily detected using counter or SCU.

  10. Physics division annual report - October 2000.

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, K. [ed.

    2000-10-16

    This report summarizes the research performed in the past year in the Argonne Physics Division. The Division's programs include operation of ATLAS as a national heavy-ion user facility, nuclear structure and reaction research with beams of heavy ions, accelerator research and development especially in superconducting radio frequency technology, nuclear theory and medium energy nuclear physics. The Division took significant strides forward in its science and its initiatives for the future in the past year. Major progress was made in developing the concept and the technology for the future advanced facility of beams of short-lived nuclei, the Rare Isotope Accelerator. The scientific program capitalized on important instrumentation initiatives with key advances in nuclear science. In 1999, the nuclear science community adopted the Argonne concept for a multi-beam superconducting linear accelerator driver as the design of choice for the next major facility in the field a Rare Isotope Accelerator (RIA) as recommended by the Nuclear Science Advisory Committee's 1996 Long Range Plan. Argonne has made significant R&D progress on almost all aspects of the design concept including the fast gas catcher (to allow fast fragmentation beams to be stopped and reaccelerated) that in large part, defined the RIA concept the superconducting rf technology for the driver accelerator, the multiple-charge-state concept (to permit the facility to meet the design intensity goals with existing ion-source technology), and designs and tests of high-power target concepts to effectively deal with the full beam power of the driver linac. An NSAC subcommittee recommended the Argonne concept and set as tie design goal Uranium beams of 100-kwatt power at 400 MeV/u. Argonne demonstrated that this goal can be met with an innovative, but technically in-hand, design.

  11. E-Division activities report

    International Nuclear Information System (INIS)

    E (Experimental Physics) Division carries out basic and applied research in atomic and nuclear physics, in materials science, and in other areas related to the missions of the Laboratory. Some of the activities are cooperative efforts with other divisions of the Laboratory, and, in a few cases, with other laboratories. Many of the experiments are directly applicable to problems in weapons and energy, some have only potential applied uses, and others are in pure physics. This report presents abstracts of papers published by E (Experimental Physics) Division staff members between July 1983 and June 1984. In addition, it lists the members of the scientific staff of the division, including visitors and students, and some of the assignments of staff members on scientific committees. A brief summary of the budget is included

  12. Charge independence and charge symmetry

    CERN Document Server

    Miller, G A; Miller, Gerald A; van Oers, Willem T H

    1994-01-01

    Charge independence and charge symmetry are approximate symmetries of nature, violated by the perturbing effects of the mass difference between up and down quarks and by electromagnetic interactions. The observations of the symmetry breaking effects in nuclear and particle physics and the implications of those effects are reviewed.

  13. Fund allocation using capacitated vehicle routing problem

    Science.gov (United States)

    Mamat, Nur Jumaadzan Zaleha; Jaaman, Saiful Hafizah; Ahmad, Rokiah Rozita; Darus, Maslina

    2014-09-01

    In investment fund allocation, it is unwise for an investor to distribute his fund into several assets simultaneously due to economic reasons. One solution is to allocate the fund into a particular asset at a time in a sequence that will either maximize returns or minimize risks depending on the investor's objective. The vehicle routing problem (VRP) provides an avenue to this issue. VRP answers the question on how to efficiently use the available fleet of vehicles to meet a given service demand, subjected to a set of operational requirements. This paper proposes an idea of using capacitated vehicle routing problem (CVRP) to optimize investment fund allocation by employing data of selected stocks in the FTSE Bursa Malaysia. Results suggest that CRVP can be applied to solve the issue of investment fund allocation and increase the investor's profit.

  14. Further capacitive imaging experiments using modified probes

    Science.gov (United States)

    Yin, Xiaokang; Li, Zhen; Yan, An; Li, Wei; Chen, Guoming; Hutchins, David A.

    2016-02-01

    In recent years, capacitive imaging (CI) is growing in popularity within the NDE communities, as it has the potential to test materials and structures for defects that are not easily tested by other techniques. In previous work, The CI technique has been successfully used on a various types of materials, including concrete, glass/carbon fibre composite, steel, etc. In such CI experiments, the probes are normally with symmetric or concentric electrodes etched onto PCBs. In addition to these conventional coplanar PCB probes, modified geometries can be made and they can lead to different applications. A brief overview of these modified probes, including high resolution surface imaging probe, combined CI/eddy current probe, and CI probe using an oscilloscope probe as the sensing electrode, is presented in this work. The potential applications brought by these probes are also discussed.

  15. Phase discriminating capacitive array sensor system

    Science.gov (United States)

    Vranish, John M. (Inventor); Rahim, Wadi (Inventor)

    1993-01-01

    A phase discriminating capacitive sensor array system which provides multiple sensor elements which are maintained at a phase and amplitude based on a frequency reference provided by a single frequency stabilized oscillator. Sensor signals provided by the multiple sensor elements are controlled by multiple phase control units, which correspond to the multiple sensor elements, to adjust the sensor signals from the multiple sensor elements based on the frequency reference. The adjustment made to the sensor signals is indicated by output signals which indicate the proximity of the object. The output signals may also indicate the closing speed of the object based on the rate of change of the adjustment made, and the edges of the object based on a sudden decrease in the adjustment made.

  16. Capacitance multiplier and filter synthesizing network

    Science.gov (United States)

    Kline, A. J. (Inventor)

    1974-01-01

    A circuit using a differential amplifier multiplies the capacitance of a discrete interating capacitor by (r sub 1 + R sub 2)/R sub 2, where R sub 1 and R sub 2 are values of discrete resistor coupling an input signal e sub 1 of the amplifier inputs. The output e sub 0 of the amplifier is fed back and added to the signal coupled by the resistor R sub 2 to the amplifier through a resistor of value R sub 1. A discrete resistor R sub x may be connected in series for a lag filter, and a discrete resistor may be connected in series with the capacitor for a lead-lag filter. Voltage dividing resistors R sub a and R sub b may be included in the feedback circuit of the amplifier output e sub o to independently adjust the circuit gain e sub i/e sub o.

  17. A capacitive bioelectrode for recording electrophysiological signals

    International Nuclear Information System (INIS)

    In this paper we describe a gel-free sensor with on-board electrode design, which capacitive couples to the skin to detect the electrical activity in the body. The integrated sensor is manufactured on a standard printed circuit board within 2.2 cm diameter enclosure that can operate through fabric or other insulation. The electrode includes amplification (60db gain) and passive band pass filtering (0.5 to 100 Hz). Active shielding surrounding the sensor plate is used to reduce noise pickup. The input referred noise, measured over the electrode bandwidth is 4 μV rms at 0.2 mm sensor distance, and 16 μV rms at 1.2 mm distance trough two cotton cloths. The bioelectrodes were coupled to the scalp trough hair for EEG signals (with 80 db gain), and coupled to the chest through clothing for ECG signals. The recorded signals show well performance of the designed bielectrode. (Author)

  18. [Wireless ECG measurement system with capacitive coupling].

    Science.gov (United States)

    Aleksandrowicz, Adrian; Walter, Marian; Leonhardt, Steffen

    2007-04-01

    This paper describes a measurement system that captures an electrocardiogram (ECG) using capacitively coupled electrodes. The measurement system was integrated into an off-the-shelf office chair (so-called "Aachen SmartChair"). Whereas for classical ECG measurement adhesive is used to attach conductively coupled electrodes to bare skin, the system presented allows ECG measurement through clothing without direct skin contact. Furthermore, a ZigBee communication module was integrated to allow wireless transmission of ECG data to a PC or an ICU patient monitor. For system validation, classical ECG using conductive electrodes was obtained simultaneously. First measurement results, including variations of cloth thickness and material, are presented and some of the system-specific problems of this approach are discussed.

  19. An integrated interface circuit with a capacitance-to-voltage converter as front-end for grounded capacitive sensors

    NARCIS (Netherlands)

    Heidary, A.; Meijer, G.C.M.

    2009-01-01

    This paper presents the analysis and design of an integrated interface for grounded capacitive sensors. To reduce the effects of parasitic cable capacitances, a feedforward technique has been applied. In combination with the use of a special front-end amplifier this yields high immunity for a parasi

  20. The hysteresis-free negative capacitance field effect transistors using non-linear poly capacitance

    Science.gov (United States)

    Fan, S.-T.; Yan, J.-Y.; Lai, D.-C.; Liu, C. W.

    2016-08-01

    A gate structure design for negative capacitance field effect transistors (NCFETs) is proposed. The hysteresis loop in current-voltage performances is eliminated by the nonlinear C-V dependence of polysilicon in the gate dielectrics. Design considerations and optimizations to achieve the low SS and hysteresis-free transfer were elaborated. The effects of gate-to-source/drain overlap, channel length scaling, interface trap states and temperature impact on SS are also investigated.

  1. Effect of different nickel precursors on capacitive behavior of electrodeposited NiO thin films

    Science.gov (United States)

    Kore, R. M.; Ghadge, T. S.; Ambare, R. C.; Lokhande, B. J.

    2016-04-01

    In the present study, the effect of nickel precursors containing different anions like nitrate, chloride and sulphate on the morphology and pseudocapacitance behavior of NiO is investigated. The NiO samples were prepared by using a potentiondynamic electrodeposition technique in the three electrode cell. Cyclic voltammetry technique was exploited for potentiodynamic deposition of the films. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), etc. The XRD reveals the cubic crystal structure for all samples. The SEM micrograph shows nanoflakelike, up grown nanoflakes and honeycomb like nanostructured morphologies for nitrate, chloride and sulphate precursors respectively. The capacitive behavior of these samples was recorded using cyclic voltammetry (CV), charge-discharge and electrochemical impedance spectroscopy (EIS) in 1 M KOH electrolyte. The specific capacitance values of NiO samples obtained using CV for nitrate, chloride and sulphate precursors were 136, 214 and 893 Fg-1 respectively, at the scan rate of 5 mVs-1. The charge discharge study shows high specific energy for the sample obtained from sulphate (23.98 Whkg-1) as compared to chloride (9.67 Whkg-1) and nitrate (4.9 Whkg-1), whereas samples of cholride (13.9 kWkg-1 and nitrate (10.5 kWkg-1) shows comparatively more specific power than samples obtained from sulphate (7.6 kWkg-1). The equivalent series resistance of NiO samples observed from EIS study are 1.34, 1.29 and 1.27 Ω respectively for nitrate, chloride and sulphate precursors. These results emphasizes that the samples obtained from sulphate precursors provides very low impedance through honeycomb like nanostructured morphology which supports good capacitive behavior of NiO.

  2. Screening length and quantum capacitance in graphene by scanning probe microscopy.

    Science.gov (United States)

    Giannazzo, F; Sonde, S; Raineri, V; Rimini, E

    2009-01-01

    A nanoscale investigation on the capacitive behavior of graphene deposited on a SiO2/n(+) Si substrate (with SiO2 thickness of 300 or 100 nm) was carried out by scanning capacitance spectroscopy (SCS). A bias V(g) composed by an AC signal and a slow DC voltage ramp was applied to the macroscopic n(+) Si backgate of the graphene/SiO(2)/Si capacitor, while a nanoscale contact was obtained on graphene by the atomic force microscope tip. This study revealed that the capacitor effective area (A(eff)) responding to the AC bias is much smaller than the geometrical area of the graphene sheet. This area is related to the length scale on which the externally applied potential decays in graphene, that is, the screening length of the graphene 2DEG. The nonstationary charges (electrons/holes) induced by the AC potential spread within this area around the contact. A(eff) increases linearly with the bias and in a symmetric way for bias inversion. For each bias V(g), the value of A(eff) is related to the minimum area necessary to accommodate the not stationary charges, according to the graphene density of states (DOS) at V(g). Interestingly, by decreasing the SiO(2) thickness from 300 to 100 nm, the slope of the A(eff) versus bias curve strongly increases (by a factor of approximately 50). The local quantum capacitance C(q) in the contacted graphene region was calculated starting from the screening length, and the distribution of the values of C(q) for different tip positions was obtained. Finally the lateral variations of the DOS in graphene was determined.

  3. One-Dimensional Fluid Model for Dust Particles in Dual-Frequency Capacitively Coupled Silane Discharges

    Institute of Scientific and Technical Information of China (English)

    LIU Xiang-Mei; SONG Yuan-Hong; WANG You-Nian

    2009-01-01

    A self-consistent fluid model, which incorporates density and flux balances of electrons, ions, neutrals and nanopar ticles, electron energy balance, and Poiaaon 's equation, is employed to investigate the capacitively coupled silane discharge modulated by dual-frequency electric sources. In this discharge process, nanoparticles are formed by a successive chemical reactions of anion with silane. The density distributions of the precursors in the dust particle formation are put forward, and the charging, transport and growth of nanoparticles are simulated. In this work, we focus our main attention on the influences of the high-frequency and low-frequency voltage on nanoparticle densities, nanoparticle charge distributions in both the bulk plasma and sheath region.

  4. Quantum fluctuations of mesoscopic damped mutual capacitance coupled double resonance RLC circuit in thermal excitation state

    Institute of Scientific and Technical Information of China (English)

    XU Xing-Lei

    2007-01-01

    Mesoscopic damped mutual capacitance coupled double resonance circuit is quantized by the method of damped harmonic oscillator quantization. Hamiltonian is diagonalized by the method of unitary transformation. The energy spectra of this circuit are given. The quantum fluctuations of the charge and current of each loop are investigated by the method of thermofield dynamics (TFD) in thermal excitation state,thermal squeezed vacuum state,thermal vacuum state and vacuum state. It is shown that the quantum fluctuations of the charge and current are related to not only circuit inherent parameter and coupled magnitude,but also quantum number of excitation,squeezed coefficients,squeezed angle and environmental temperature. And the quantum fluctuations increase with the increase of temperature and decay with time.

  5. Determination of charge carrier profiles - Problems and limitations of methods at short ranges

    International Nuclear Information System (INIS)

    The determination of charge carrier profiles near the surface produced by low-energy ion implantation is partly possible by the aid of a modified capacitance-voltage method thermally stimulated current (TSC) spectroscopy, and Hall measurements as exemplified by silicon samples. The capacitance spectroscopy by means of Schottky junctions and the effect of deep defects on the first, the spectroscopy of deep levels by the TSC method and differential Hall measurements are presented

  6. Continuous capacitive deionization-electrodialysis reversal through electrostatic shielding for desalination and deionization of water

    Energy Technology Data Exchange (ETDEWEB)

    Dermentzis, Konstantinos [Technological Education Institute, T.E.I. of Kavala, School of Technological Applications, Department of Science, Laboratory of Chemical Technology and Electrochemistry, Agios Loucas, 65404 Kavala (Greece); Ouzounis, Konstantinos [Democritus University of Thrace, School of Engineering, Department of Environmental Engineering, Laboratory of Environmental Chemistry, 67100 Xanthi (Greece)

    2008-10-15

    We report a new concept for capacitive deionization with simple and cheap porous bipolar intermediate graphite electrodes which is operated continuously by constant or alternating polarity without any down time for electrode saturation, regeneration and rinsing steps and certainly without any permselective ion exchange membranes. The proposed process utilizes the advantages of the classical electrodeionization technologies combining them all to a unified continuous capacitive deionization-continuous electrodeionization-electrodialysis-electrodialysis reversal process. Separate and unchanged diluate and concentrate compartments are created in two modes, first by periodical charging/discharging the bipolar intermediate electrodes through a pulsating electric field and second by simultaneous charging/discharging them through a constant or pulsating electric field and electrostatic shielding. Because of coion permeation and the convenience of alternating the polarity without any negative impact on the deionization process, the new technique is less affected by the known membrane associated limitation, such as concentration polarization, limiting current density or scaling. The new electrochemical deionization technique is suitable for regeneration of ion exchange resins and production of high purity deionized water, removal of heavy metal ions from industrial effluents and desalination of brackish or seawater. (author)

  7. Characterization of electrical and mechanical activities of rabbit uterus associated with the presence of capacitated and non-capacitated spermatozoa

    Directory of Open Access Journals (Sweden)

    J.F. Lazcano-Reyes

    2013-12-01

    Full Text Available To investigate the effects capacitated spermatozoa may exert upon motility of the rabbit uterus, both contractility and electrical activity (frequency and intensity were measured in 3 distinctive uterine segments of anaesthetized does: horn (UH, uterotubal junction (UTJ and tube (UT after 1 natural mating, 2 infusion of either seminal plasma or PBS, 3 infusion of either capacitated or non-capacitated spermatozoa. Basal values were: 17.1, 15.7, 16.4 g (contractility, P>0.05; 3.5, 3.5, 3.4 Hz (frequency, P>0.05; 0.49, 0.50, 0.57 μV (intensity, P>0.05 for UH, UTJ, UT, respectively. Seminal plasma caused an increase (P<0.05 in the UH contractility: 26.3 vs. 11.7 (natural mating and 17.0 g (PBS; it also caused a decrease (P<0.05 in electrical intensity at the UTJ: 0.24 vs. 0.67 (natural mating and 0.58 μV (PBS. The presence of either capacitated or non-capacitated spermatozoa caused no changes in contractility and electrical frequency in any of the uterine segments. However, there was a change in electrical intensity at UTJ (0.37 vs. 0.57 μV for non-capacitated and capacitated spermatozoa, respectively; P<0.05. There were also differences between segments by treatment: UTJ (0.37 vs. UT (0.59 μV for non-capacitated; UH (0.46 vs. UT (0.71 μV for capacitated spermatozoa (P<0.05. In conclusion, use of this experimental model showed that uterine electrical activity was slightly modified by the presence of capacitated spermatozoa.

  8. Charged Leptons

    CERN Document Server

    Albrecht, J; Babu, K; Bernstein, R H; Blum, T; Brown, D N; Casey, B C K; Cheng, C -h; Cirigliano, V; Cohen, A; Deshpande, A; Dukes, E C; Echenard, B; Gaponenko, A; Glenzinski, D; Gonzalez-Alonso, M; Grancagnolo, F; Grossman, Y; Harnik, R; Hitlin, D G; Kiburg, B; Knoepfe, K; Kumar, K; Lim, G; Lu, Z -T; McKeen, D; Miller, J P; Ramsey-Musolf, M; Ray, R; Roberts, B L; Rominsky, M; Semertzidis, Y; Stoeckinger, D; Talman, R; Van De Water, R; Winter, P

    2013-01-01

    This is the report of the Intensity Frontier Charged Lepton Working Group of the 2013 Community Summer Study "Snowmass on the Mississippi", summarizing the current status and future experimental opportunities in muon and tau lepton studies and their sensitivity to new physics. These include searches for charged lepton flavor violation, measurements of magnetic and electric dipole moments, and precision measurements of the decay spectrum and parity-violating asymmetries.

  9. Hydraulic Resistance and Capacitance in the Soil—Plant System

    Institute of Scientific and Technical Information of China (English)

    SHAOMING-AN; L.P.SIMMONDS

    1991-01-01

    In this paper,the hydraulic resistances and capacitances were evaluated.based on the development of non-linear model of water flow in the soil-plant system and the simulating experiment work.The results show that the mean hydraulic resistance in the soil-plant system is 6.79×109 MPa·S·m-3;the mean hydraulic capacitance in the system is 5.2×10-7m3·MPa-1.In the components of hydraulic capacitance in the system,the capacitance in soil (81.8×10-6m3·MPa-1)is the biggest and its variability with soil water potential is extremely strong,the capacitance in plant (5.3×10-7m3·MPa-1) is much smaller than that in soil,and the capacitance in shoots (15.5×10-7m3·MPa-1) is bigger than that in roots (8.4×10-7m3·MPa-1).An interesting result is that the capacitance in plant is almost equivalent to that in the soil-plant system.

  10. Electron heating in capacitively coupled RF plasmas: a unified scenario

    Science.gov (United States)

    Brinkmann, Ralf Peter

    2016-02-01

    Electron heating in radio-frequency capacitively coupled plasmas (RF-CCP) is studied from first principles. The starting points are the electron equations of continuity and motion, with ionization neglected but electric and pressure forces and elastic collisions with the neutral background taken into account. Poisson’s equation self-consistently calculates the electric field; the ion density is assumed as a given. Postulating that the Debye length {λ\\text{D}} is small compared to the sheath length scale l and the applied frequency {ω\\text{RF}} is small compared to the electron plasma frequency {ω\\text{pe}} , an asymptotic expansion in the smallness parameter ε ={λ\\text{D}}/l∼ {ω\\text{RF}}/{ω\\text{pe}} is conducted. As has been demonstrated before (Brinkmann 2015 Plasma Sources Sci. Technol. 24 064002), this ansatz gives an expression—the smooth step model (SSM)—which yields (i) the space charge field in the unipolar region, (ii) the generalized Ohmic field in the ambipolar region, and (iii) a smooth interpolation for the rapid transition in between. Using the SSM and formulas for the electron density and the electron flux, expressions for the electric force and the electric power density are established which hold up to O≤ft(ε \\right) . Integrating over the sheath and taking the phase average, a representation for the total dissipated power is found as a sum of four physically distinct contributions. All terms correspond to electron heating mechanisms which are (explicitly or implicitly) already known but were so far discussed only within mutually incompatible frameworks.

  11. Nanoporous activated carbon cloth for capacitive deionization of aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Han-Jun [Department of Materials Science, Hanseo University, Seosan, 352-820 (Korea, Republic of); Lee, Jong-Ho [Department of Chemistry, Hanseo University, Seosan, 352-820 (Korea, Republic of); Ahn, Hong-Joo [Korea Atomic Energy Research Institute, Daejeon, 305-600 (Korea, Republic of); Jeong, Yongsoo [Korea Institute of Machinery and Materials, Changwon, 641-010 (Korea, Republic of); Kim, Young-Jig [Department of Metallurgical Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Chi, Choong-Soo [School of Advanced Materials Engineering, Kookmin University, Seoul, 136-702 (Korea, Republic of)]. E-mail: cschi@kookmin.ac.kr

    2006-09-25

    Activated nanostructured-carbon cloths with a high ratio of surface area to volume are used as electrode for capacitive deionization. The electrochemical properties on capacitive deionization for NaCl solution have been investigated to improve efficiency of capacitive deionization properties from aqueous solution, employing chemical surface-modification by etching in alkaline and acidic solution. The removal efficiency of inorganic salts of activated carbon cloths by chemical modification significantly increased. Specially the carbon cloth surface modified in HNO{sub 3} showed an effect of improvement in the CDI efficiency due to not only ion adsorption by an electric double layer, but also electron transfer by Faradaic reaction.

  12. Bloch inductance in small-capacitance Josephson junctions.

    Science.gov (United States)

    Zorin, A B

    2006-04-28

    We show that the electrical impedance of a small-capacitance Josephson junction also includes, in addition to the capacitive term -i/(omega)CB, an inductive term i(omega)LB. Similar to the known Bloch capacitance CB(q), the Bloch inductance LB(q) also depends periodically on the quasicharge, q, and its maximum value achieved at q=e(mod 2e) always exceeds the value of the Josephson inductance of this junction LJ(phi) at fixed phi=0. The effect of the Bloch inductance on the dynamics of a single junction and a one-dimensional array is described.

  13. Flexible transparent iontronic film for interfacial capacitive pressure sensing.

    Science.gov (United States)

    Nie, Baoqing; Li, Ruya; Cao, Jennifer; Brandt, James D; Pan, Tingrui

    2015-10-21

    A flexible, transparent iontronic film is introduced as a thin-film capacitive sensing material for emerging wearable and health-monitoring applications. Utilizing the capacitive interface at the ionic-electronic contact, the iontronic film sensor offers a large unit-area capacitance (of 5.4 μF cm(-2) ) and an ultrahigh sensitivity (of 3.1 nF kPa(-1) ), which is a thousand times greater than that of traditional solid-state counterparts. PMID:26333011

  14. Electrochemical Capacitance DNA Sensing at Hairpin-Modified Au Electrodes

    OpenAIRE

    Joel Rivera-Gandía; Maria del Mar Maldonado; Yarimar De La Torre-Meléndez; Edwin O. Ortiz-Quiles; Vargas-Barbosa, Nella M.; Cabrera, Carlos R.

    2011-01-01

    An interfacial capacitance measurement electrochemical technique has been used for the sensing of self-assembled DNA hairpin probes (M. tuberculosis and B. anthracis) attached to Au electrodes. The double-layer capacitance (Cdl) was determined with electrochemical perturbations from 0.2 V to 0.5 V versus Ag/AgCl at a Au/M. tuberculosis DNA hairpin probe at surface coverage Au electrodes. The capacitance study was done at pH 7, which was necessary to maintain the M. tuberculosis and B. anthrac...

  15. Building an academic colorectal division.

    Science.gov (United States)

    Koltun, Walter A

    2014-06-01

    Colon and rectal surgery is fully justified as a valid subspecialty within academic university health centers, but such formal recognition at the organizational level is not the norm. Creating a colon and rectal division within a greater department of surgery requires an unfailing commitment to academic concepts while promulgating the improvements that come in patient care, research, and teaching from a specialty service perspective. The creation of divisional identity then opens the door for a strategic process that will grow the division even more as well as provide benefits to the institution within which it resides. The fundamentals of core values, academic commitment, and shared success reinforced by receptive leadership are critical. Attention to culture, commitment, collaboration, control, cost, and compensation leads to a successful academic division of colon and rectal surgery. PMID:25067922

  16. Charging process of polyurethane based composites under electronic irradiation: Effects of cellulose fiber content

    Science.gov (United States)

    Hadjadj, Aomar; Jbara, Omar; Tara, Ahmed; Gilliot, Mickael; Dellis, Jean-Luc

    2013-09-01

    The study deals with the charging effect of polyurethanes-based composites reinforced with cellulose fibers, under electronic beam irradiation in a scanning electron microscope. The results indicate that the leakage current and the trapped charge as well as the kinetics of charging process significantly change beyond a critical concentration of 10% cellulose fibers. These features are correlated with the cellulose concentration-dependence of the electrical properties, specifically resistivity and capacitance, of the composite.

  17. Flexible 3D Nanoporous Graphene for Desalination and Bio-decontamination of Brackish Water via Asymmetric Capacitive Deionization.

    Science.gov (United States)

    El-Deen, Ahmed G; Boom, Remko M; Kim, Hak Yong; Duan, Hongwei; Chan-Park, Mary B; Choi, Jae-Hwan

    2016-09-28

    Nanoporous graphene based materials are a promising nanostructured carbon for energy storage and electrosorption applications. We present a novel and facile strategy for fabrication of asymmetrically functionalized microporous activated graphene electrodes for high performance capacitive desalination and disinfection of brackish water. Briefly, thiocarbohydrazide coated silica nanoparticles intercalated graphene sheets are used as a sacrificial material for creating mesoporous graphene followed by alkaline activation process. This fabrication procedure meets the ideal desalination pore diameter with ultrahigh specific surface area ∼ 2680 m(2) g(-1) of activated 3D graphene based micropores. The obtained activated graphene electrode is modified by carboxymethyl cellulose as negative charge (COO(-2)) and disinfectant quaternary ammonium cellulose with positively charged polyatomic ions of the structure (NR4(+)). Our novel asymmetric coated microporous activated 3D graphene employs nontoxic water-soluble binder which increases the surface wettability and decreases the interfacial resistance and moreover improves the electrode flexibility compared with organic binders. The desalination performance of the fabricated electrodes was evaluated by carrying out single pass mode experiment under various cell potentials with symmetric and asymmetric cells. The asymmetric charge coated microporous activated graphene exhibits exceptional electrosorption capacity of 18.43 mg g(-1) at a flow rate of 20 mL min(-1) upon applied cell potential of 1.4 V with initial NaCl concentration of 300 mg L(-1), high charge efficiency, excellent recyclability, and, moreover, good antibacterial behavior. The present strategy provides a new avenue for producing ultrapure water via green capacitive deionization technology.

  18. Characterization of electrical and mechanical activities of rabbit uterus associated with the presence of capacitated and non-capacitated spermatozoa

    OpenAIRE

    J.F. Lazcano-Reyes; Montiel, J.L.; Medrano, A.

    2013-01-01

    To investigate the effects capacitated spermatozoa may exert upon motility of the rabbit uterus, both contractility and electrical activity (frequency and intensity) were measured in 3 distinctive uterine segments of anaesthetized does: horn (UH), uterotubal junction (UTJ) and tube (UT) after 1) natural mating, 2) infusion of either seminal plasma or PBS, 3) infusion of either capacitated or non-capacitated spermatozoa. Basal values were: 17.1, 15.7, 16.4 g (contractility, P>0.05); 3.5, 3.5, ...

  19. Reactor Engineering Division annual report

    International Nuclear Information System (INIS)

    Research and development activities in the Division of Reactor Engineering in fiscal 1981 are described. The work of the Division is closely related to development of multipurpose Very High Temperature Gas Cooled Reactor and fusion reactor, and development of Liquid Metal Fast Breeder Reactor carried out by Power Reactor and Nuclear Fuel Development Corporation. Contents of the report are achievements in fields such as nuclear data and group constants, theoretical method and code development, integral experiment and analysis, shielding, reactor and nuclear instrumentation, reactor control and diagnosis, and fusion reactor technology, and activities of the Committee on Reactor Physics. (author)

  20. Reactor Engineering Division annual report

    International Nuclear Information System (INIS)

    Research activities in the Division of Reactor Engineering in fiscal 1977 are described. Works of the Division are development of multi-purpose Very High Temperature Gas Cooled Reactor, fusion reactor engineering, and development of Liquid Metal Fast Breeder Reactor for Power Reactor and Nuclear Fuel Development Corporation. Contents of the report are nuclear data and group constants, theoretical method and code development, integral experiment and analysis, shielding, heat transfer and fluid dynamics, reactor and nuclear instrumentation, dynamics analysis and control method development, fusion reactor technology, and Committee on Reactor Physics. (Author)

  1. Reactor Engineering Division annual report

    International Nuclear Information System (INIS)

    Research activities conducted in Reactor Engineering Division in fiscal 1975 are summarized in this report. Works in the division are closely related to the development of multi-purpose High-temperature Gas Cooled Reactor, the development of Liquid Metal Fast Breeder Reactor by Power Reactor and Nuclear Fuel Development Corporation, and engineering research of thermonuclear fusion reactor. Many achievements are described concerning nuclear data and group constants, theoretical method and code development, integral experiment and analysis, shielding, heat transfer and fluid dynamics, reactor and nuclear instrumentation, dynamics analysis and control method development, fusion reactor technology and activities of the Committee on Reactor Physics. (auth.)

  2. Combinatorial Algorithms for Capacitated Network Design

    CERN Document Server

    Hajiaghayi, MohammadTaghi; Kortsarz, Guy; Nutov, Zeev

    2011-01-01

    We focus on designing combinatorial algorithms for the Capacitated Network Design problem (Cap-SNDP). The Cap-SNDP is the problem of satisfying connectivity requirements when edges have costs and hard capacities. We begin by showing that the Group Steiner tree problem (GST) is a special case of Cap-SNDP even when there is connectivity requirement between only one source-sink pair. This implies the first poly-logarithmic lower bound for the Cap-SNDP. We next provide combinatorial algorithms for several special cases of this problem. The Cap-SNDP is equivalent to its special case when every edge has either zero cost or infinite capacity. We consider a special case, called Connected Cap-SNDP, where all infinite-capacity edges in the solution are required to form a connected component containing the sinks. This problem is motivated by its similarity to the Connected Facility Location problem [G+01,SW04]. We solve this problem by reducing it to Submodular tree cover problem, which is a common generalization of Con...

  3. An uncooled capacitive sensor for IR detection

    Science.gov (United States)

    Siebke, Georg; Gerngroß, Kathrin; Holik, Peter; Schmitz, Sam; Rohloff, Markus; Tätzner, Simon; Steltenkamp, Siegfried

    2014-06-01

    The beetle Melanophila acuminata detects forest fires from distances as far as 80 miles away. To accomplish this, the beetle uses highly specific IR receptors with a diameter of approximately 15 μm. These receptors are mechanoreceptors that detect deformations induced by the absorption of radiation. Although the detection mechanism is understood in principle, it is still unclear how the beetle reaches such high sensitivity. In this work, we present the biomimetic approach of an uncooled IR sensor based on the beetle's receptors. This sensor is based on a fluid-filled pressure cell and operates at room temperature. Upon absorbing IR radiation, the fluid heats up and expands. The expanding fluid deflects one electrode of a plate capacitor. By measuring the change in capacitance, the volume increase and the absorbed energy can be inferred. To prevent the risk of damage at high energy absorption, a compensation mechanism is presented in this work. The mechanism prevents large but slow volume changes inside the pressure cell by a microfluidic connection of the pressure cell with a compensation chamber. The channel and the compensation chamber act as a microfluidic low-pass filter and do not affect the overall sensitivity above an appropriate cut-off frequency. Using MEMS technology, we are able to incorporate the complete system into a silicon chip with an area of a few mm2. Here, we show a proof-of-concept and first measurements of the sensor.

  4. Design Considerations in Capacitively Coupled Plasmas

    Science.gov (United States)

    Song, Sang-Heon; Ventzek, Peter; Ranjan, Alok

    2015-11-01

    Microelectronics industry has driven transistor feature size scaling from 10-6 m to 10-9 m during the past 50 years, which is often referred to as Moore's law. It cannot be overstated that today's information technology would not have been so successful without plasma material processing. One of the major plasma sources for the microelectronics fabrication is capacitively coupled plasmas (CCPs). The CCP reactor has been intensively studied and developed for the deposition and etching of different films on the silicon wafer. As the feature size gets to around 10 nm, the requirement for the process uniformity is less than 1-2 nm across the wafer (300 mm). In order to achieve the desired uniformity, the hardware design should be as precise as possible before the fine tuning of process condition is applied to make it even better. In doing this procedure, the computer simulation can save a significant amount of resources such as time and money which are critical in the semiconductor business. In this presentation, we compare plasma properties using a 2-dimensional plasma hydrodynamics model for different kinds of design factors that can affect the plasma uniformity. The parameters studied in this presentation include chamber accessing port, pumping port, focus ring around wafer substrate, and the geometry of electrodes of CCP.

  5. Locating Depots for Capacitated Vehicle Routing

    CERN Document Server

    Goertz, Inge Li

    2011-01-01

    We study a location-routing problem in the context of capacitated vehicle routing. The input is a set of demand locations in a metric space and a fleet of k vehicles each of capacity Q. The objective is to locate k depots, one for each vehicle, and compute routes for the vehicles so that all demands are satisfied and the total cost is minimized. Our main result is a constant-factor approximation algorithm for this problem. To achieve this result, we reduce to the k-median-forest problem, which generalizes both k-median and minimum spanning tree, and which might be of independent interest. We give a (3+c)-approximation algorithm for k-median-forest, which leads to a (12+c)-approximation algorithm for the above location-routing problem, for any constant c>0. The algorithm for k-median-forest is just t-swap local search, and we prove that it has locality gap 3+2/t; this generalizes the corresponding result known for k-median. Finally we consider the "non-uniform" k-median-forest problem which has different cost ...

  6. Locating Depots for Capacitated Vehicle Routing

    DEFF Research Database (Denmark)

    Gørtz, Inge Li; Nagarajan, Viswanath

    2011-01-01

    We study a location-routing problem in the context of capacitated vehicle routing. The input to k-LocVRP is a set of demand locations in a metric space and a fleet of k vehicles each of capacity Q. The objective is to locate k depots, one for each vehicle, and compute routes for the vehicles so...... median forest, which leads to a (12+E)-approximation algorithm for k-LocVRP, for any constant E > 0. The algorithm for k median forest is t-swap local search, and we prove that it has locality gap 3 + 2 t ; this generalizes the corresponding result for k median [3]. Finally we consider the k median...... forest problem when there is a different (unrelated) cost function c for the MST part, i.e. the objective is Eu∈V d(u, S) + c(MST(V/S) ). We show that the locality gap for this problem is unbounded even under multi-swaps, which contrasts with the c = d case. Nevertheless, we obtain a constant...

  7. Spatial resolution in electrical capacitance tomography

    CERN Document Server

    Lucas, Jérôme; Oussar, Yacine; Holé, Stéphane

    2015-01-01

    Electrical Capacitance Tomography (ECT) is an imaging technique providing the distribution of permittivity in a medium by the mean of electrodes. As for any imaging systems, the reachable spatial resolution is a key parameter. In this paper the spatial resolution of ECT sensors is analyzed in terms of the accuracy of an object position and of the ability to distinguish between two close objects. Cylindrical geometry sensors are particularly studied and the example of a square geometry sensor is used to show how to study any other geometries. In cylindrical geometries, it is shown that a 50% gap between electrodes is a good compromise and that increasing the number of electrodes improves the spatial resolution near the electrodes but decreases the spatial resolution in the center. The best spatial resolution at the center of the sensor is obtained with 3 or 4 electrodes. In the square geometry studied, it is shown that a better distribution of the spatial resolution is obtained when there are electrodes in the...

  8. Label-free RNA aptamer-based capacitive biosensor for the detection of C-reactive protein.

    Science.gov (United States)

    Qureshi, Anjum; Gurbuz, Yasar; Kallempudi, Saravan; Niazi, Javed H

    2010-08-28

    In this study, we report a novel aptamer-based capacitive label-free biosensor for monitoring transducing aptamer-protein recognition events, based on charge distribution under the applied frequency by non-Faradaic impedance spectroscopy (NFIS). This approach to capacitive biosensors is reported for the first time in this study, is reagent-less in processing and is developed using gold interdigitated (GID) capacitor arrays functionalized with synthetic RNA aptamers. The RNA atpamers served as biorecognition elements for C-reactive protein (CRP), a biomarker for cardiovascular disease risk (CVR). The signal is generated as a result of the change in relative capacitance occurring as a result of the formation of an RNA-CRP complex on GID capacitors with the applied AC electrical frequency (50-350 MHz). The dispersion peak of the capacitance curve was dependent on the CRP concentration and tends to shift toward lower frequencies, accompanied by the increase in relaxation time due to the increased size of the aptamer-CRP complex. The dissociation constant (K(d)) calculated from the non-linear regression analysis of the relative capacitance change with the applied frequency showed that strong binding of CRP occurred at 208 MHz (K(d) = 1.6 microM) followed by 150 MHz (K(d) = 4.2 microM) and 306 MHz (K(d) = 3.4 microM) frequencies. The dynamic detection range for CRP is determined to be within 100-500 pg ml(-1). Our results demonstrates the behavior of an RNA-protein complex on GID capacitors under an applied electric field, which can be extended to other pairs of affinity biomolecules as well as for the development of electrical biosensor systems for different applications, including the early diagnosis of diseases.

  9. Label-free RNA aptamer-based capacitive biosensor for the detection of C-reactive protein.

    Science.gov (United States)

    Qureshi, Anjum; Gurbuz, Yasar; Kallempudi, Saravan; Niazi, Javed H

    2010-08-28

    In this study, we report a novel aptamer-based capacitive label-free biosensor for monitoring transducing aptamer-protein recognition events, based on charge distribution under the applied frequency by non-Faradaic impedance spectroscopy (NFIS). This approach to capacitive biosensors is reported for the first time in this study, is reagent-less in processing and is developed using gold interdigitated (GID) capacitor arrays functionalized with synthetic RNA aptamers. The RNA atpamers served as biorecognition elements for C-reactive protein (CRP), a biomarker for cardiovascular disease risk (CVR). The signal is generated as a result of the change in relative capacitance occurring as a result of the formation of an RNA-CRP complex on GID capacitors with the applied AC electrical frequency (50-350 MHz). The dispersion peak of the capacitance curve was dependent on the CRP concentration and tends to shift toward lower frequencies, accompanied by the increase in relaxation time due to the increased size of the aptamer-CRP complex. The dissociation constant (K(d)) calculated from the non-linear regression analysis of the relative capacitance change with the applied frequency showed that strong binding of CRP occurred at 208 MHz (K(d) = 1.6 microM) followed by 150 MHz (K(d) = 4.2 microM) and 306 MHz (K(d) = 3.4 microM) frequencies. The dynamic detection range for CRP is determined to be within 100-500 pg ml(-1). Our results demonstrates the behavior of an RNA-protein complex on GID capacitors under an applied electric field, which can be extended to other pairs of affinity biomolecules as well as for the development of electrical biosensor systems for different applications, including the early diagnosis of diseases. PMID:20648264

  10. Enhancement of the carbon electrode capacitance by brominated hydroquinones

    Science.gov (United States)

    Gastol, Dominika; Walkowiak, Jedrzej; Fic, Krzysztof; Frackowiak, Elzbieta

    2016-09-01

    This paper presents supercapacitors utilizing new redox-active electrolytes with bromine species. Two sources of Br specimen were investigated, i.e. dibromodihydroxybenzene dissolved in KOH and potassium bromide dissolved in KOH with hydroxybenzene additive. KOH-activated carbon, exhibiting a well-developed porosity, was incorporated as an electrode material. The tested systems revealed a capacitance enhancement explained by Br- and partial BrO3- redox activity. The optimisation of the electrolyte concentration resulted in a capacitance value of 314 F g-1 achieved at 1.1 V voltage range. Good cyclability performance (11% capacitance loss) combined with a high capacitance value (244 F g-1) were obtained for the system operating in 0.2 mol L- 1 C6H4Br2O2 in 2 mol L-1 KOH electrolytic solution.

  11. Segmented Capacitance Sensor with Partially Released Inactive Segments

    Directory of Open Access Journals (Sweden)

    Lev Jakub

    2015-09-01

    Full Text Available Material throughput measurement is important for many applications, for example yield maps creation or control of mass flow in stationary lines. Quite perspective can be the capacitive throughput method. Segmented capacitance sensor (SCS is discussed in this paper. SCS is a compromise between simple capacitive throughput sensors and electrical capacitance tomography sensors. The SCS variant with partially released inactive segments is presented. The mathematical model of SCS was created and verified by measurements. A good correspondence between measured and computed values was found and it can be stated that the proposed mathematical model was verified. During measurement the voltage values on the inactive segments were monitored as well. On the basis of the measurement there was found that these values are significantly influenced by material distribution.

  12. Design of Excitation Capacitance for Self-Excited Induction Generator

    Directory of Open Access Journals (Sweden)

    Swati Devabhaktuni

    2011-12-01

    Full Text Available This paper presents simple and accurate approach to compute the minimum value of capacitance required for initiating the voltage build-up in a three-phase selfexcited induction generator. Based on the steady-state equivalent circuit model different numerical methods for solving frequency are known from previous literature, which are of 6th order polynomial. In this paper the order of the polynomial is reduced to the 4thorder frequency with a new, simple and direct method is developed to find the capacitance requirement. Critical values of the impedance and speed, below which the machine fails to self excite irrespective of the capacitance used, are found to exist. Closed form solutions for capacitance are derived for no-load and RL loads. Experimental results obtained on a 3.5kW induction machine confirm the feasibility and accuracy of the proposed method.

  13. A Review of High Voltage Drive Amplifiers for Capacitive Actuators

    DEFF Research Database (Denmark)

    Huang, Lina; Zhang, Zhe; Andersen, Michael A. E.

    2012-01-01

    This paper gives an overview of the high voltage amplifiers, which are used to drive capacitive actuators. The amplifiers for both piezoelectric and DEAP (dielectric electroactive polymer) actuator are discussed. The suitable topologies for driving capacitive actuators are illustrated in detail, ......, including linear as well as switched mode amplifiers. In the past much attention has been paid on the driver for piezoelectric actuator. As DEAP is a type of new material, there is not much literature reference for it.......This paper gives an overview of the high voltage amplifiers, which are used to drive capacitive actuators. The amplifiers for both piezoelectric and DEAP (dielectric electroactive polymer) actuator are discussed. The suitable topologies for driving capacitive actuators are illustrated in detail...

  14. Composite metal-oxide device has voltage sensitive capacitance

    Science.gov (United States)

    Mattauch, R. J.; Viola, T. J., Jr.

    1970-01-01

    Device with step function variation of the capacitance is useful for voltage-controlled oscillator circuits and as a voltage-sensitive switch. Simplicity of construction makes the device suitable for large-scale integration, microelectronic circuits.

  15. Structure and Capacitance of Electrical Double Layers inside Micropores

    Science.gov (United States)

    Feng, Guang; Qiao, Rui; Huang, Jingsong; Sumpter, Bobby G.; Meunier, Vincent

    2010-03-01

    Recent experiments indicate that the specific capacitance of micropores (diameter less than 2nm) increases anomalously as the pore size decreases^[1]. To understand the physical origin of this discovery, we performed a series of molecular dynamics simulations to study the electrical double layers (EDLs) in micropores with different shapes (tube vs slit) and pore sizes (0.668nm - 3.342nm). Several different aqueous electrolytes (K^+, Na^+, Cl^-, and F^- in water) were used in these micropores. We quantified the structure of EDLs inside the pores, and computed the capacitance of EDLs. The scaling of capacitance shows a qualitative agreement with the experimental observations. We attribute the anomalous enhancement of capacitance in micropores to the short-range ionelectrode and ionsolvent interactions.[1] J. Chmiola, G. Yushin, Y. Gogotsi, C. Portet, P. Simon, and P.L. Taberna, Science 2006, 313, 1760.

  16. Integration of Capacitive Micromachined Ultrasound Transducers to Microfluidic Devices

    KAUST Repository

    Viržonis, Darius

    2013-10-22

    The design and manufacturing flexibility of capacitive micromachined ultrasound transducers (CMUT) makes them attractive option for integration with microfluidic devices both for sensing and fluid manipulation. CMUT concept is introduced here by presentin

  17. Prostaglandin modulation of mouse and human sperm capacitation.

    Science.gov (United States)

    Herrero, M B; Viggiano, J M; Boquet, M; Gimeno, M A

    1997-09-01

    To determine whether prostaglandins produce a capacitation and/or acrosome reaction, the effect of prostaglandins on capacitated mouse spermatozoa and the effect of prostaglandin pre-incubation on human and mouse spermatozoa were studied. Prostaglandins did not induce an acrosome reaction in capacitated mouse sperm. PGE1 pre-incubation in a protein-free medium enhanced acrosome loss of mouse sperm challenged with A-23187 or solubilized mouse zona pellucida. Human sperm were pre-incubated in media containing prostaglandins, and an acrosome reaction was induced with calcium ionophore or human follicular fluid. PGE1 pre-incubation enhanced acrosome loss by human sperm when the action was induced with calcium ionophore, but had no effect on follicular fluid induction. We conclude that PGE1 acts as a capacitating factor in vitro for mouse spermatozoa, and enhances acrosome-reaction induction with calcium ionophore in human spermatozoa.

  18. Voidage measurement based on genetic algorithm and electrical capacitance tomography

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-wei; WANG Bao-liang; HUANG Zhi-yao; LI Hai-qing

    2005-01-01

    A new voidage measurement method based on electrical capacitance tomography (ECT) technique, Genetic Algorithm (GA) and Partial Least Square (PLS) method was proposed. The voidage measurement model, linear capacitance combination, was developed to measure on-line voidage. GA and PLS method were used to determine the coefficients of the voidage measurement model. GA was used to explore the optimal capacitance combination which gave significant contribution to the voidage measurement. PLS method was applied to determine the weight coefficient of the contribution of each capacitance to the voidage measurement. Flow pattern identification result was introduced to improve the voidage measurement accuracy. Experimental results showed that the proposed voidage measurement method is effective and that the measurement accuracy is satisfactory.

  19. Macroscopic fibres of CNTs as electrodes for multifunctional electric double layer capacitors: from quantum capacitance to device performance

    Science.gov (United States)

    Senokos, E.; Reguero, V.; Palma, J.; Vilatela, J. J.; Marcilla, Rebeca

    2016-02-01

    In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through control of the synthetic and assembly processes of the fibres, it is possible to obtain an active material that combines a surface area of 250 m2 g-1, high electrical conductivity (3.5 × 105 S m-1) and mechanical properties in the high-performance range including toughness (35 J g-1) comparable to that of aramid fibre (e.g. Kevlar). These properties are a consequence of the predominant orientation of the CNTs, observed by wide- and small-angle X-ray diffraction, and to the exceptionally long CNT length on the millimetre scale. Cyclic voltammetry measurements in a three-electrode configuration and using 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) ionic liquid electrolyte, show that the CNT fibres have a large quantum capacitance, evidenced by the near linear dependence of geometric capacitance (and conductivity) on potential bias. This reflects the low dimensionality of the CNT building blocks, which were purposely synthesised to have 1-5 layers and a high degree of graphitization. From the charge-discharge measurements of supercapacitor devices with symmetric CNT fibre electrodes we obtain power and energy densities as high as 58 kW kg-1 and 14 Wh kg-1, respectively. These record-high values for CNT fibre-based supercapacitors, are a consequence of the low equivalent series resistance due to the high conductivity of the fibres, the large contribution from quantum capacitance, and the wide stability window of the ionic liquid (3.5 V). Cycle life experiments demonstrate stable capacitance and energy retention over 10 000 cycles of charge-discharge at 3.5 V.In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through

  20. Mechanics and charging of nanoparticle agglomerates

    Science.gov (United States)

    Shin, Weon Gyu

    Precipitator. It has been reported that the particle morphology affects both bipolar and unipolar charging processes. Nevertheless, knowledge about the charging of non-spherical particles such as asbestos fibers and fractal agglomerates is still lacking. From this study it was found that the effect of dielectric constant of materials on unipolar diffusion charging of nanoparticles is very small and the experimental results are in a good agreement with Fuchs (1963)' theory. The effect of agglomerate morphology on unipolar charging characteristic was examined both experimentally and analytically in terms of the mean charge per particle. Both geometric surface area and electrical capacitance are known as two important parameters to determine the mean charge of non-spherical particles. A new model to predict the electrical capacitance of loose agglomerate particles as a function of mobility diameter was developed incorporating electrical mobility and electrostatics theories. This study shows that the electrical capacitance contributes to increase the mean charge per particle of agglomerates more than the geometric surface area, especially in the transition regime. The estimates of geometric surface area and electrical capacitance were used to predict the mean charge from Chang (1981)'s model and the predicted results are reasonably in good agreement with experimental data.

  1. Charge fluctuations in nano-scale capacitors

    CERN Document Server

    Limmer, David T; Salanne, Mathieu; Chandler, David; Madden, Paul A; van Roij, René; Rotenberg, Benjamin

    2013-01-01

    The fluctuations of the charge on an electrode contain information on the microscopic correlations within the adjacent fluid and their effect on the electronic properties of the interface. We investigate these fluctuations using molecular dynamics simulations in a constant-potential ensemble with histogram reweighting techniques. This approach offers an efficient and accurate route to the differential capacitance and is broadly applicable. We demonstrate these methods with three different capacitors: pure water between platinum electrodes, and a pure as well as a solvent-based organic electrolyte each between graphite electrodes. The total charge distributions with the pure solvent and solvent-based electrolytes are remarkably Gaussian, while in the pure ionic liquid the total charge distribution displays distinct non-Gaussian features, suggesting significant potential-driven changes in the organization of the interfacial fluid.

  2. Current Progress of Capacitive Deionization for Removal of Pollutant Ions

    Science.gov (United States)

    Gaikwad, Mahendra S.; Balomajumder, Chandrajit

    2016-08-01

    A mini review of a recently developing water purification technology capacitive deionization (CDI) applied for removal of pollutant ions is provided. The current progress of CDI for removal of different pollutant ions such as arsenic, fluoride, boron, phosphate, lithium, copper, cadmium, ferric, and nitrate ions is presented. This paper aims at motivating new research opportunities in capacitive deionization technology for removal of pollutant ions from polluted water.

  3. Capacitive Sensors for Measuring Masses of Cryogenic Fluids

    Science.gov (United States)

    Nurge, Mark; Youngquist, Robert

    2003-01-01

    An effort is under way to develop capacitive sensors for measuring the masses of cryogenic fluids in tanks. These sensors are intended to function in both microgravitational and normal gravitational settings, and should not be confused with level sensors, including capacitive ones. A sensor of this type is conceptually simple in the sense that (1) it includes only one capacitor and (2) if properly designed, its single capacitance reading should be readily convertible to a close approximation of the mass of the cryogenic fluid in the tank. Consider a pair of electrically insulated electrodes used as a simple capacitive sensor. In general, the capacitance is proportional to the permittivity of the dielectric medium (in this case, a cryogenic fluid) between the electrodes. The success of design and operation of a sensor of the present type depends on the accuracy of the assumption that to a close approximation, the permittivity of the cryogenic fluid varies linearly with the density of the fluid. Data on liquid nitrogen, liquid oxygen, and liquid hydrogen, reported by the National Institute of Standards and Technology, indicate that the permittivities and densities of these fluids are, indeed, linearly related to within a few tenths of a percent over the pressure and temperature regions of interest. Hence, ignoring geometric effects for the moment, the capacitance between two electrodes immersed in the fluid should vary linearly with the density, and, hence, with the mass of the fluid. Of course, it is necessary to take account of the tank geometry. Because most cryogenic tanks do not have uniform cross sections, the readings of level sensors, including capacitive ones, are not linearly correlated with the masses of fluids in the tanks. In a sensor of the present type, the capacitor electrodes are shaped so that at a given height, the capacitance per unit height is approximately proportional to the cross-sectional area of the tank in the horizontal plane at that

  4. Probing Quantum Capacitance in a 3D Topological Insulator

    Science.gov (United States)

    Kozlov, D. A.; Bauer, D.; Ziegler, J.; Fischer, R.; Savchenko, M. L.; Kvon, Z. D.; Mikhailov, N. N.; Dvoretsky, S. A.; Weiss, D.

    2016-04-01

    We measure the quantum capacitance and probe thus directly the electronic density of states of the high mobility, Dirac type two-dimensional electron system, which forms on the surface of strained HgTe. Here we show that observed magnetocapacitance oscillations probe—in contrast to magnetotransport—primarily the top surface. Capacitance measurements constitute thus a powerful tool to probe only one topological surface and to reconstruct its Landau level spectrum for different positions of the Fermi energy.

  5. Direct measurement of specific membrane capacitance in neurons.

    OpenAIRE

    Gentet, L.J.; Stuart, G J; Clements, J D

    2000-01-01

    The specific membrane capacitance (C(m)) of a neuron influences synaptic efficacy and determines the speed with which electrical signals propagate along dendrites and unmyelinated axons. The value of this important parameter remains controversial. In this study, C(m) was estimated for the somatic membrane of cortical pyramidal neurons, spinal cord neurons, and hippocampal neurons. A nucleated patch was pulled and a voltage-clamp step was applied. The exponential decay of the capacitative char...

  6. Simultaneous capacitance and amperometric measurements of exocytosis: a comparison.

    OpenAIRE

    Oberhauser, A F; Robinson, I M; Fernandez, J. M.

    1996-01-01

    We measured the exocytotic response induced by flash photolysis of caged compounds in isolated mast cells and chromaffin cells. Vesicle fusion was measured by monitoring the cell membrane capacitance. The release of vesicular contents was followed by amperometry. In response to a GTP gamma S stimulus we found that the time integral of the amperometric current could be superimposed on the capacitance trace. This shows that the integrated amperometric signal provides an alternative method of me...

  7. Graphene-based quantum capacitance wireless vapor sensors

    OpenAIRE

    Deen, David A.; Olson, Eric J.; Ebrish, Mona A.; Koester, Steven J.

    2013-01-01

    A wireless vapor sensor based upon the quantum capacitance effect in graphene is demonstrated. The sensor consists of a metal-oxide-graphene variable capacitor (varactor) coupled to an inductor, creating a resonant oscillator circuit. The resonant frequency is found to shift in proportion to water vapor concentration for relative humidity (RH) values ranging from 1% to 97% with a linear frequency shift of 5.7 +- 0.3 kHz / RH%. The capacitance values extracted from the wireless measurements ag...

  8. Enhanced Salt Removal in an Inverted Capacitive Deionization Cell Using Amine Modified Microporous Carbon Cathodes.

    Science.gov (United States)

    Gao, Xin; Omosebi, Ayokunle; Landon, James; Liu, Kunlei

    2015-09-15

    Microporous SpectraCarb carbon cloth was treated using nitric acid to enhance negative surface charges of COO(-) in a neutral solution. This acid-treated carbon was further modified by ethylenediamine to attach -NH2 surface functional groups, resulting in positive surface charges of -NH3(+) via pronation in a neutral solution. Through multiple characterizations, in comparison to pristine SpectraCarb carbon, amine-treated SpectraCarb carbon displays a decreased potential of zero charge but an increased point of zero charge, which is opposed to the effect obtained for acid-treated SpectraCarb carbon. An inverted capacitive deionization cell was constructed using amine-treated cathodes and acid-treated anodes, where the cathode is the negatively polarized electrode and the anode is the positively polarized electrode. Constant-voltage switching operation using NaCl solution showed that the salt removal capacity was approximately 5.3 mg g(-1) at a maximum working voltage of 1.1/0 V, which is an expansion in both the salt capacity and potential window from previous i-CDI results demonstrated for carbon xerogel materials. This improved performance is accounted for by the enlarged cathodic working voltage window through ethylenediamine-derived functional groups, and the enhanced microporosity of the SpectraCarb electrodes for salt adsorption. These results expand the use of i-CDI for efficient desalination applications. PMID:26302134

  9. Performance of single carbon granules as perspective for larger scale capacitive bioanodes

    Science.gov (United States)

    Borsje, Casper; Liu, Dandan; Sleutels, Tom H. J. A.; Buisman, Cees J. N.; ter Heijne, Annemiek

    2016-09-01

    The use of high surface area electrodes, like carbon-based felt or granules, in Bioelectrochemical Systems is crucial for high volumetric current production. In case activated carbon granules are used, charge can also be stored in the form of an electric double layer in the pores, which has been shown to improve bioanode performance. So far, it is not known how much current can be generated by a single granule. In this study, we investigate the current production and charge storage behavior of a single carbon granule. Two types of activated carbon granules and one graphite granule are tested to find the untapped potential of granular bioanodes. A single activated carbon granule produces up to 0.6 mA, corresponding to 60 mA cm-3 granule volume at -300 mV vs. Ag/AgCl anode potential. Charge - discharge experiments show that capacitive granules produced 1.3-2.0 times more charge compared to a graphite granule with low surface area. When extrapolated to other granular systems, our study indicates that the current generated by granular bioanodes can be improved with several orders of magnitude, which could form the basis of an economically feasible Microbial Fuel Cell.

  10. Optimizing the energy efficiency of capacitive deionization reactors working under real-world conditions.

    Science.gov (United States)

    García-Quismondo, Enrique; Santos, Cleis; Lado, Julio; Palma, Jesús; Anderson, Marc A

    2013-10-15

    Capacitive deionization (CDI) is a rapidly emerging desalination technology that promises to deliver clean water while storing energy in the electrical double layer (EDL) near a charged surface in a capacitive format. Whereas most research in this subject area has been devoted to using CDI for removing salts, little attention has been paid to the energy storage aspect of the technology. However, it is energy storage that would allow this technology to compete with other desalination processes if this energy could be stored and reused efficiently. This requires that the operational aspects of CDI be optimized with respect to energy used both during the removal of ions as well as during the regeneration cycle. This translates into the fact that currents applied during deionization (charging the EDL) will be different from those used in regeneration (discharge). This paper provides a mechanistic analysis of CDI in terms of energy consumption and energy efficiencies during the charging and discharging of the system under several scenarios. In a previous study, we proposed an operational buffer mode in which an effective separation of deionization and regeneration steps would allow one to better define the energy balance of this CDI process. This paper reports on using this concept, for optimizing energy efficiency, as well as to improve upon the electro-adsorption of ions and system lifetime. Results obtained indicate that real-world operational modes of running CDI systems promote the development of new and unexpected behavior not previously found, mainly associated with the inhomogeneous distribution of ions across the structure of the electrodes. PMID:24015835

  11. Optimizing the energy efficiency of capacitive deionization reactors working under real-world conditions.

    Science.gov (United States)

    García-Quismondo, Enrique; Santos, Cleis; Lado, Julio; Palma, Jesús; Anderson, Marc A

    2013-10-15

    Capacitive deionization (CDI) is a rapidly emerging desalination technology that promises to deliver clean water while storing energy in the electrical double layer (EDL) near a charged surface in a capacitive format. Whereas most research in this subject area has been devoted to using CDI for removing salts, little attention has been paid to the energy storage aspect of the technology. However, it is energy storage that would allow this technology to compete with other desalination processes if this energy could be stored and reused efficiently. This requires that the operational aspects of CDI be optimized with respect to energy used both during the removal of ions as well as during the regeneration cycle. This translates into the fact that currents applied during deionization (charging the EDL) will be different from those used in regeneration (discharge). This paper provides a mechanistic analysis of CDI in terms of energy consumption and energy efficiencies during the charging and discharging of the system under several scenarios. In a previous study, we proposed an operational buffer mode in which an effective separation of deionization and regeneration steps would allow one to better define the energy balance of this CDI process. This paper reports on using this concept, for optimizing energy efficiency, as well as to improve upon the electro-adsorption of ions and system lifetime. Results obtained indicate that real-world operational modes of running CDI systems promote the development of new and unexpected behavior not previously found, mainly associated with the inhomogeneous distribution of ions across the structure of the electrodes.

  12. Optimizing the Materials Response in Humidity Capacitive Sensors

    Directory of Open Access Journals (Sweden)

    Elham Noroozi Afshar

    2015-10-01

    Full Text Available The number of humidity outputs on the cap of a cylindrical capacitance sensor is optimized by designing three different probes with direct and indirect windows. The time interval is measured within which 30-70 % humidity can influence the dielectric constant and conductivity of the capacitance when exposed to a range of relative humidity. It is then compared with a simple set-up including a simplified equivalent circuit. The direct probes had four and double outputs on the window of the cylindrical capacitive sensor while the indirect probe had a thin plastic layer only. We observed that the dielectric constant and its conductivity depend closely to the humidity outgoing pathway and also to the increasing rate of humidity between the capacitance plates. The final variation in the materials properties alters the capacitance of the sensor which is measured simply by a LCR. This technique presents a simple method for tracking the recovery and reliability of the humidity sensors over time and assists in optimizing and controlling the materials response to the relative environment humidity. As a result, by controlling the environment humidity rate (0.02 %/s., we could measure the increment rate of capacitance with accuracy of 0.01 pf/%.

  13. Macroscopic fibres of CNTs as electrodes for multifunctional electric double layer capacitors: from quantum capacitance to device performance.

    Science.gov (United States)

    Senokos, E; Reguero, V; Palma, J; Vilatela, J J; Marcilla, Rebeca

    2016-02-14

    In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through control of the synthetic and assembly processes of the fibres, it is possible to obtain an active material that combines a surface area of 250 m(2) g(-1), high electrical conductivity (3.5 × 10(5) S m(-1)) and mechanical properties in the high-performance range including toughness (35 J g(-1)) comparable to that of aramid fibre (e.g. Kevlar). These properties are a consequence of the predominant orientation of the CNTs, observed by wide- and small-angle X-ray diffraction, and to the exceptionally long CNT length on the millimetre scale. Cyclic voltammetry measurements in a three-electrode configuration and using 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) ionic liquid electrolyte, show that the CNT fibres have a large quantum capacitance, evidenced by the near linear dependence of geometric capacitance (and conductivity) on potential bias. This reflects the low dimensionality of the CNT building blocks, which were purposely synthesised to have 1-5 layers and a high degree of graphitization. From the charge-discharge measurements of supercapacitor devices with symmetric CNT fibre electrodes we obtain power and energy densities as high as 58 kW kg(-1) and 14 Wh kg(-1), respectively. These record-high values for CNT fibre-based supercapacitors, are a consequence of the low equivalent series resistance due to the high conductivity of the fibres, the large contribution from quantum capacitance, and the wide stability window of the ionic liquid (3.5 V). Cycle life experiments demonstrate stable capacitance and energy retention over 10,000 cycles of charge-discharge at 3.5 V. PMID:26809811

  14. Synthesis of Few-Layer MoS2 Nanosheets-Wrapped Polyaniline Hierarchical Nanostructures for Enhanced Electrochemical Capacitance Performance

    International Nuclear Information System (INIS)

    Graphical abstract: The scientific motivation of this work is to synthesize a hierarchical core-sheath PANi@MoS2 nanostructure as an advanced electrode material for high-performance electrochemical capacitor applications. Hierarchical core-sheath PANi@MoS2 nanostructure is prepared in a one-pot synthesis via a hydrothermal redox reaction between ammonium tetrathiomolybdate and polyaniline nanofibers. The obtained PANi@MoS2 electrode displays a good electrochemical capacitance performance with a specific capacity of 450 F g−1 under 0.5 M H2SO4. More importantly, the core-sheath structure of PANi@MoS2 electrode enhances the structural stability during the electrochemical process and thus improves the electrochemical cycling stability of the electrode significantly, which retains 80% in specific capacity after 2000 charge/discharge processes, higher than 47% of that with individual PANi nanofibers electrode. - Abstract: We report a facile strategy to synthesize a hierarchical core-sheath PANi@MoS2 nanocomposite as an advanced electrode material for high-performance electrochemical capacitor applications. Hierarchical core-sheath PANi@MoS2 nanostructure is prepared in a one-pot synthesis via a hydrothermal redox reaction between ammonium tetrathiomolybdate and polyaniline nanofibers. Structural and morphological characterizations of the as-prepared PANi@MoS2 nanocomposite are investigated by Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. The obtained PANi@MoS2 electrode displays a good electrochemical capacitance performance with a specific capacitance of 450 F g−1 under 0.5 M H2SO4. More importantly, the core-sheath structure of PANi@MoS2 electrode enhances the structural stability during the electrochemical process and thus improves the electrochemical cycling stability of the electrode significantly, which retains 80% in

  15. Research and Experiments on a Unipolar Capacitive Voltage Sensor.

    Science.gov (United States)

    Zhou, Qiang; He, Wei; Li, Songnong; Hou, Xingzhe

    2015-01-01

    Voltage sensors are an important part of the electric system. In service, traditional voltage sensors need to directly contact a high-voltage charged body. Sensors involve a large volume, complex insulation structures, and high design costs. Typically an iron core structure is adopted. As a result, ferromagnetic resonance can occur easily during practical application. Moreover, owing to the multilevel capacitor divider, the sensor cannot reflect the changes of measured voltage in time. Based on the electric field coupling principle, this paper designs a new voltage sensor; the unipolar structure design solves many problems of traditional voltage sensors like the great insulation design difficulty and high costs caused by grounding electrodes. A differential signal input structure is adopted for the detection circuit, which effectively restrains the influence of the common-mode interference signal. Through sensor modeling, simulation and calculations, the structural design of the sensor electrode was optimized, miniaturization of the sensor was realized, the voltage division ratio of the sensor was enhanced, and the phase difference of sensor measurement was weakened. The voltage sensor is applied to a single-phase voltage class line of 10 kV for testing. According to the test results, the designed sensor is able to meet the requirements of accurate and real-time measurement for voltage of the charged conductor as well as to provide a new method for electricity larceny prevention and on-line monitoring of the power grid in an electric system. Therefore, it can satisfy the development demands of the smart power grid. PMID:26307992

  16. Research and Experiments on a Unipolar Capacitive Voltage Sensor

    Directory of Open Access Journals (Sweden)

    Qiang Zhou

    2015-08-01

    Full Text Available Voltage sensors are an important part of the electric system. In service, traditional voltage sensors need to directly contact a high-voltage charged body. Sensors involve a large volume, complex insulation structures, and high design costs. Typically an iron core structure is adopted. As a result, ferromagnetic resonance can occur easily during practical application. Moreover, owing to the multilevel capacitor divider, the sensor cannot reflect the changes of measured voltage in time. Based on the electric field coupling principle, this paper designs a new voltage sensor; the unipolar structure design solves many problems of traditional voltage sensors like the great insulation design difficulty and high costs caused by grounding electrodes. A differential signal input structure is adopted for the detection circuit, which effectively restrains the influence of the common-mode interference signal. Through sensor modeling, simulation and calculations, the structural design of the sensor electrode was optimized, miniaturization of the sensor was realized, the voltage division ratio of the sensor was enhanced, and the phase difference of sensor measurement was weakened. The voltage sensor is applied to a single-phase voltage class line of 10 kV for testing. According to the test results, the designed sensor is able to meet the requirements of accurate and real-time measurement for voltage of the charged conductor as well as to provide a new method for electricity larceny prevention and on-line monitoring of the power grid in an electric system. Therefore, it can satisfy the development demands of the smart power grid.

  17. Nuclear Physics Division progress report

    International Nuclear Information System (INIS)

    The 1983 progress report of the Nuclear Physics Division, UKAEA Harwell, is divided into four main topics. These are a) nuclear data and technology for nuclear power; b) nuclear studies; c) applications of nuclear and associated techniques, including ion beam techniques and moessbauer spectroscopy; and d) accelerator operation, maintenance and development. (U.K.)

  18. Nuclear Physics division progress report

    International Nuclear Information System (INIS)

    Work undertaken by the Nuclear Physics Division of AERE, Harwell during 1980 is presented under the headings: (1) Nuclear Data and Technology for Nuclear Power. (2) Nuclear Studies. (3) Applications of Nuclear and Associated Techniques. (4) Accelerator Operation, Maintenance and Development. Reports, publications and conference papers presented during the period are given and members of staff listed. (U.K.)

  19. Environmental Transport Division: 1979 report

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, C.E. Jr.; Schubert, J.F.; Bowman, W.W.; Adams, S.E.

    1980-03-01

    During 1979, the Environmental Transport Division (ETD) of the Savannah River Laboratory conducted atmospheric, terrestrial, aquatic, and marine studies, which are described in a series of articles. Separate abstracts were prepared for each. Publications written about the 1979 research are listed at the end of the report.

  20. Home | Division of Cancer Prevention

    Science.gov (United States)

    Our Research The Division of Cancer Prevention (DCP) conducts and supports research to determine a person's risk of cancer and to find ways to reduce the risk. This knowledge is critical to making progress against cancer because risk varies over the lifespan as genetic and epigenetic changes can transform healthy tissue into cancer. |

  1. 76 FR 63659 - Antitrust Division

    Science.gov (United States)

    2011-10-13

    ... pursuant to Section 6(b) of the Act on February 2, 2005 (70 FR 5486). The last notification was filed with...) of the Act on July 20, 2011 (76 FR 43347). Patricia A. Brink, Director of Civil Enforcement... Antitrust Division Notice Pursuant to the National Cooperative Research and Production Act of 1993;...

  2. 78 FR 17430 - Antitrust Division

    Science.gov (United States)

    2013-03-21

    ... pursuant to Section 6(b) of the Act on April 4, 2003 (68 FR 16552). The last notification was filed with... Section 6(b) of the Act on March 23, 2012 (77 FR 17095). Patricia A. Brink, Director of Civil Enforcement... Antitrust Division Notice Pursuant to the National Cooperative Research and Production Act of...

  3. Manpower Division Looks at CETA

    Science.gov (United States)

    American Vocational Journal, 1977

    1977-01-01

    The Manpower Division at the American Vocational Association (AVA) convention in Houston was concerned about youth unemployment and about the Comprehensive Employment and Training Act (CETA)--its problems and possibilities. The panel discussion reported here reveals some differing perspectives and a general consensus--that to improve their role in…

  4. Inversive meadows and divisive meadows

    NARCIS (Netherlands)

    J.A. Bergstra; C.A. Middelburg

    2009-01-01

    An inversive meadow is a commutative ring with identity and a total multiplicative inverse operation whose value at 0 is 0. Previously, inversive meadows were shortly called meadows. In this paper, we introduce divisive meadows, which are inversive meadows with the multiplicative inverse operation r

  5. Environmental Transport Division: 1979 report

    International Nuclear Information System (INIS)

    During 1979, the Environmental Transport Division (ETD) of the Savannah River Laboratory conducted atmospheric, terrestrial, aquatic, and marine studies, which are described in a series of articles. Separate abstracts were prepared for each. Publications written about the 1979 research are listed at the end of the report

  6. Novel integration of ultrathin Al2O3 with low-k dielectric as bilayer liner for capacitance optimization and stress mitigation in Cu through-silicon-via

    Science.gov (United States)

    Zhang, Lin; Li, Hong Yu; Shang, Yang; Yoo, Woosik; Yu, Hao; Tan, Chuan Seng

    2016-04-01

    Through-silicon-via (TSV) used in three-dimensional (3D) stacked dies must present small electrical parasitic, such as capacitance, to allow for low latency signal transmission. Stable TSV capacitance is desired to overcome the spatial circuit performance variation caused by non-uniform hot-spot heating. In this work, a novel combination of low-k with ultrathin Al2O3 bilayer liner is successfully integrated in the TSV. The TSV capacitance is reduced by ˜26% as compared to plasma-enhanced tetrahydrothosilicate (PETEOS) oxide liner. Stable TSV capacitance within the operating voltage of interest (˜0-5 V) is achieved by operating the TSV in a stable accumulation capacitance region. The positive shift in the flat-band voltage (ΔV FB = +19 V) is achieved by utilizing Al2O3-induced negative fixed charge (|Q f| = 1.3 × 1012 cm-2) at the Si/low-k interface. Leakage current density of the bilayer liner is improved to a level comparable with the PETEOS oxide liner post annealing [forming gas (N2/H2) at 350 °C for 2 h or 400 °C for 0.5 h]. Low-k material with a smaller elastic modulus improves the thermo-mechanical stress exerted on the surrounding Si substrate compared with PETEOS oxide.

  7. A QUALITATIVE ANALYSIS OF BIOMASS FLOW SENSING BEHAVIOR USING CAPACITIVE TECHNIQUE

    OpenAIRE

    Rumana Tasnim; Sheroz Khan; Musse Mohamud; Atika Arshad

    2016-01-01

    Flowsensing technology from today’s application perspective has gained significant research interest over the past few years. Among the existing sensing techniques, electrostatic and capacitive sensing techniques have proven promising although cable capacitance and stray capacitance cause inaccuracy while measuring very small capacitances. The existing measurement circuit model is complicated and has flawed electrode arrangement. By sensing very small capacitive variation, the developed capac...

  8. Operational Characterization of Divisibility of Dynamical Maps

    Science.gov (United States)

    Bae, Joonwoo; Chruściński, Dariusz

    2016-07-01

    In this work, we show the operational characterization to the divisibility of dynamical maps in terms of the distinguishability of quantum channels. It is proven that the distinguishability of any pair of quantum channels does not increase under divisible maps, in which the full hierarchy of divisibility is isomorphic to the structure of entanglement between system and environment. This shows that (i) channel distinguishability is the operational quantity signifying (detecting) divisibility (indivisibility) of dynamical maps and (ii) the decision problem for the divisibility of maps is as hard as the separability problem in entanglement theory. We also provide the information-theoretic characterization to the divisibility of maps with conditional min-entropy.

  9. Surface-charge accumulation effects on open-circuit voltage in organic solar cells based on photoinduced impedance analysis.

    Science.gov (United States)

    Zang, Huidong; Hsiao, Yu-Che; Hu, Bin

    2014-03-14

    The accumulation of dissociated charge carriers plays an important role in reducing the loss occurring in organic solar cells. We find from light-assisted capacitance measurements that the charge accumulation inevitably occurred at the electrode and photovoltaic layer interface for bulk-heterojunction ITO/PEDOT:PSS/P3HT:PCBM/Ca/Al solar cells. Our results indicate, for the first time through impedance measurements, that the charge accumulation exists at the anode side of the device, and more importantly, we successfully identify the type of charge accumulated. Further study shows that the charge accumulation can significantly affect open circuit voltage and short circuit current. As a result, our experimental results from light assisted capacitance measurements provide a new understanding of the loss in open-circuit voltage and short-circuit photocurrent based on charge accumulation. Clearly, controlling charge accumulation presents a new mechanism to improve the photovoltaic performance of organic solar cells.

  10. Morphology-dependent capacitive properties of three nanostructured polyanilines through interfacial polymerization in various acidic media

    International Nuclear Information System (INIS)

    Highlights: • Preparing three PANI nanostructures in HCl, H2SO4, and HNO3 reaction media during a slow interfacial polymerization. • Obtaining nanofibrous, nanogranular and hollow ball–like morphologies in the order of oxidizability of acids. • Demonstrating high specific capacitance, good rate performance and long cycle life of PANI nanofibers. - Abstract: Three nanostructured polyanilines (PANIs) were prepared by interfacial polymerization using different inorganic acids including HCl, H2SO4, and HNO3 as reaction media, respectively. The morphology-dependent structure and properties of as-prepared PANIs were characterized by means of scanning electron microscope, ultraviolet-visible spectra, Fourier transform infrared spectroscopy and X-ray diffraction patterns. Meanwhile, the electrochemical performance of the fabricated electrodes was evaluated by cyclic voltammetry, galvanostatic charge/discharge measurement, and electrochemical impedance spectroscopy. It is found that the reaction medium plays a vital role in deciding the final morphology and structure of product when a slow reaction rate occurred in interfacial polymerization. The as-prepared PANIs exhibited nanofibrous, nanogranular and hollow ball-like morphologies according to the order of the relative oxidizing ability of HCl < H2SO4 < HNO3, respectively. Furthermore, the capacitive properties of these composites as electrode materials highly depended not only on their morphologies but also on the conductivity, crystalline property and the inhibitory role of the lattice during the redox process, as well as the interparticle contact resistance. It is demonstrated that PANI nanofibers prepared in HCl medium exhibited high specific capacitance, good rate performance and long cycle life for the supercapacitor application

  11. Development of a highly pixelated direct charge sensor, Topmetal-I, for ionizing radiation imaging

    CERN Document Server

    Fan, Yan; Huang, Guangming; Li, Xiaoting; Mei, Yuan; Pei, Hua; Sun, Quan; Sun, Xiangming; Wang, Dong; Wang, Zhen; Xiao, Le; Yang, Ping

    2014-01-01

    Using industrial standard 0.35{\\mu}m CMOS Integrated Circuit process, we realized a highly pixelated sensor that directly collects charge via metal nodes placed on the top of each pixel and forms two dimensional images of charge cloud distribution. The first version, Topmetal-I, features a 64x64 pixel array of 80{\\mu}m pitch size. Direct charge calibration reveals an average capacitance of 210fF per pixel. The charge collection noise is near the thermal noise limit. With the readout, individual pixel channels exhibit a most probable equivalent noise charge of 330e-.

  12. Study on capacitance evolving mechanism of polypyrrole during prolonged cycling.

    Science.gov (United States)

    Wang, JingPing; Xu, Youlong; Wang, Jie; Zhu, Jianbo; Bai, Yang; Xiong, Lilong

    2014-02-01

    A simple model on the evolution mechanism of PPy capacitance during prolonged cycling offers a reasonably description on the rapid increase and decay of PPy capacitance in 1 M 1-ethyl-3-methylimidazolium tetrafluoroborate/propylene carbonate (EtMeImBF4/PC). The capacitance of PPy films reached a very high specific capacitance of 420 F·g(-1) after 15 cycles when they worked in 1 M MeEt3ImBF4/PC. However, the capacitance rapidly decreased to 5% after only 400 cycles. The electronic conductivity and protonation level on the nitrogen site of PPy films rapidly decreased with the increase of cyclic number. The salt of EtMeImBF4 was monitored in PPy matrix by FTIR spectra after 400 cycles. The EQCM results indicated that a lot of 1-ethyl-3-methylimidazolium cations (EtMeIm(+)) were inserted during reduction process and retained in PPy matrix. The detained EtMeIm(+) cations bonded with doped p-toluenesulfonate anions (PTS(-)) in PPy matrix or BF4(-) anions from electrolyte and formed salts. Small amount of salts in PPy matrix can open more channels of ion insertion and resulted in a very high capacitance after 15 cycles. The continuous combination of detained EtMeIm(+) cations with doping anions of PTS(-) resulted in the rapid decrease of PPy protonation level on the nitrogen site and formation of compensate semiconductor state in PPy matrix. This should be responsible for the rapid decay of PPy conductivity and capacitance. The continuous accumulation of salts resulted in the great increase of PPy internal resistance. PMID:24428582

  13. Charge collection efficiency of GaAs detectors studied with low-energy heavy charged particles

    CERN Document Server

    Bates, R; Linhart, V; O'Shea, V; Pospísil, S; Raine, C; Smith, K; Sinor, M; Wilhelm, I

    1999-01-01

    Epitaxially grown GaAs layers have recently been produced with sufficient thickness and low enough free carrier concentration to permit their use as radiation detectors. Initial tests have shown that the epi-material behaves as a classical semiconductor as the depletion behaviour follows the square root dependency on the applied bias. This article presents the results of measurements of the growth of the active depletion depth with increasing bias using low-energy protons and alpha particles as probes for various depths and their comparison to values extrapolated from capacitance measurements. From the proton and alpha particle spectroscopic measurements, an active depth of detector material that collects 100% of the charge generated inside it was determined. The consistency of these results with independent capacitance measurements supports the idea that the GaAs epi-material behaves as a classical semiconductor. (author)

  14. Highly porous activated carbons from resource-recovered Leucaena leucocephala wood as capacitive deionization electrodes.

    Science.gov (United States)

    Hou, Chia-Hung; Liu, Nei-Ling; Hsi, Hsing-Cheng

    2015-12-01

    Highly porous activated carbons were resource-recovered from Leucaena leucocephala (Lam.) de Wit. wood through combined chemical and physical activation (i.e., KOH etching followed by CO2 activation). This invasive species, which has severely damaged the ecological economics of Taiwan, was used as the precursor for producing high-quality carbonaceous electrodes for capacitive deionization (CDI). Carbonization and activation conditions strongly influenced the structure of chars and activated carbons. The total surface area and pore volume of activated carbons increased with increasing KOH/char ratio and activation time. Overgasification induced a substantial amount of mesopores in the activated carbons. In addition, the electrochemical properties and CDI electrosorptive performance of the activated carbons were evaluated; cyclic voltammetry and galvanostatic charge/discharge measurements revealed a typical capacitive behavior and electrical double layer formation, confirming ion electrosorption in the porous structure. The activated-carbon electrode, which possessed high surface area and both mesopores and micropores, exhibited improved capacitor characteristics and high electrosorptive performance. Highly porous activated carbons derived from waste L. leucocephala were demonstrated to be suitable CDI electrode materials. PMID:26135977

  15. Substrate dependant capacitive performance of spray pyrolysed titanium oxide (TiO2) thin films

    Science.gov (United States)

    Fugare, B. Y.; Ingole, R. S.; Ambare, R. C.; Lokhande, B. J.

    2016-04-01

    Using 60 ml, 0.06 M aqueous solution of potassium titanium oxalate (pto), thin films of titanium oxide were prepared by using well known spray pyrolysis technique. Depositions of the films carried out at 723° K by maintain the spray rate 12 Cc/min. prepared thin films were characterized structurally, morphologically and electrochemically. Sample shows tetragonal crystal structure with rutile as prominent phase at very low deposition temperature. SEM morphology shows porous, dense, nanorods and nanoplates like morphology. The electrochemical cyclic voltammetery shows mixed capacitive behavior. The specific capacitance values observed from cyclic voltammetery in 1 M NaOH are 2497.19, 29.60, 424.22 F/g. for the electrode deposited on copper, FTO and stainless steel (SS) respectively. Charge discharge behavior was observed for the samples deposited on stainless steel gives specific energy (SE), specific power (SP) and efficiency (η) are 43.25 Wh/kg, 35.25 kW/kg and 98.22 % respectively. Impedance study was carried out in the frequency range 1 mHz to 1 MHz exhibits very less internal resistance 1.066 Ohm for the deposited electrode.

  16. Physiographic divisions of the conterminous U. S.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This is a polygon coverage of Physiographic Divisions in the conterminous United States. It was automated from Fenneman's 1:7,000,000-scale map, "Physical Divisions...

  17. Physics Division Annual Report, April 1, 1994--March 31, 1995

    International Nuclear Information System (INIS)

    This report summarizes the research performed over the past year by the Argonne Physics Division in the areas of nuclear and atomic physics. The Division's programs in nuclear physics include operation of ATLAS as a national heavy-ion user facility and related accelerator development, nuclear structure research and reactions with beams of heavy ions, primarily at ATLAS but also using forefront instrumentation elsewhere, medium energy nuclear physics at SLAC, Fermilab, Novosibirsk, DESY and CEBAF, and nuclear theory. In atomic and molecular physics the research programs are directed towards studies of highly charged ions at ATLAS, and towards studies with synchrotron radiation, currently at the National Synchrotron Light Source at Brookhaven but also in preparation for the future program at the Advanced Photon Source at Argonne. Separate abstracts have been indexed for individual contributions to this report

  18. Health, Safety, and Environment Division

    Energy Technology Data Exchange (ETDEWEB)

    Wade, C [comp.

    1992-01-01

    The primary responsibility of the Health, Safety, and Environmental (HSE) Division at the Los Alamos National Laboratory is to provide comprehensive occupational health and safety programs, waste processing, and environmental protection. These activities are designed to protect the worker, the public, and the environment. Meeting these responsibilities requires expertise in many disciplines, including radiation protection, industrial hygiene, safety, occupational medicine, environmental science and engineering, analytical chemistry, epidemiology, and waste management. New and challenging health, safety, and environmental problems occasionally arise from the diverse research and development work of the Laboratory, and research programs in HSE Division often stem from these applied needs. These programs continue but are also extended, as needed, to study specific problems for the Department of Energy. The results of these programs help develop better practices in occupational health and safety, radiation protection, and environmental science.

  19. Cell division in apicomplexan parasites.

    Science.gov (United States)

    Francia, Maria E; Striepen, Boris

    2014-02-01

    Toxoplasma gondii and Plasmodium falciparum are important human pathogens. These parasites and many of their apicomplexan relatives undergo a complex developmental process in the cells of their hosts, which includes genome replication, cell division and the assembly of new invasive stages. Apicomplexan cell cycle progression is both globally and locally regulated. Global regulation is carried out throughout the cytoplasm by diffusible factors that include cell cycle-specific kinases, cyclins and transcription factors. Local regulation acts on individual nuclei and daughter cells that are developing inside the mother cell. We propose that the centrosome is a master regulator that physically tethers cellular components and that provides spatial and temporal control of apicomplexan cell division.

  20. Division of solid state physics

    International Nuclear Information System (INIS)

    This report gives a survey of the present research projects at the division of solid state physics, Inst. of Technology, Uppsala University. The projects fall within the fields of magnetism, i.e. spin glasses, ordered magnetic structures and itinerant electron magnetism, and optics, i.e. properties of crystalline and amorphous materials for selective transmission and absorption in connection with energy-related research. (author)