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Sample records for charge sensitive amplifier

  1. High sensitivity charge amplifier for ion beam uniformity monitor

    DOEpatents

    Johnson, Gary W.

    2001-01-01

    An ion beam uniformity monitor for very low beam currents using a high-sensitivity charge amplifier with bias compensation. The ion beam monitor is used to assess the uniformity of a raster-scanned ion beam, such as used in an ion implanter, and utilizes four Faraday cups placed in the geometric corners of the target area. Current from each cup is integrated with respect to time, thus measuring accumulated dose, or charge, in Coulombs. By comparing the dose at each corner, a qualitative assessment of ion beam uniformity is made possible. With knowledge of the relative area of the Faraday cups, the ion flux and areal dose can also be obtained.

  2. Reset charge sensitive amplifier for NaI(Tl) gamma-ray spectrometer.

    PubMed

    Zeng, Guoqiang; Tan, Chengjun; Li, Qiang; Ge, Liangquan; Liu, Xiyao; Luo, Qun

    2015-03-01

    The time constant of the output signal of the front-end readout circuit of a traditional gamma-ray spectrometer with a NaI(Tl)+PMT structure is affected by temperature, measurement environment and the signal transmission cable, so it is difficult to get a good resolution spectrum, especially at higher counting rates. In this paper, a reset charge sensitive amplifier (RCSA) is designed for the gamma-ray spectrometer with a NaI(Tl)+PMT structure. The designed RCSA outputs a step signal, thus enabling the acquisition of double-exponential signals with a stable time constant by using the next stage of a CR differentiating circuit. The designed RCSA is mainly composed of a basic amplifying circuit, a reset circuit and a dark current compensation circuit. It provides the output step signal through the integration of the PMT output charge signal. When the amplitude of the step signal exceeds a preset voltage threshold, it triggers the reset circuit to generate a reset pulse (about 5µs pulse width) to reset the output signal. Experimental results demonstrated that the designed RCSA achieves a charge sensitivity of 4.26×10(10)V/C, with a zero capacitance noise of 51.09fC and a noise slope of 1.98fC/pF. Supported by the digital shaping algorithm of the digital multi-channel analyzer (DMCA), it can maintain good energy resolution with high counting rates up to 150kcps and with a temperature range from -19°C to 50°C. PMID:25544664

  3. Charge amplifier with bias compensation

    DOEpatents

    Johnson, Gary W.

    2002-01-01

    An ion beam uniformity monitor for very low beam currents using a high-sensitivity charge amplifier with bias compensation. The ion beam monitor is used to assess the uniformity of a raster-scanned ion beam, such as used in an ion implanter, and utilizes four Faraday cups placed in the geometric corners of the target area. Current from each cup is integrated with respect to time, thus measuring accumulated dose, or charge, in Coulombs. By comparing the dose at each corner, a qualitative assessment of ion beam uniformity is made possible. With knowledge of the relative area of the Faraday cups, the ion flux and areal dose can also be obtained.

  4. A charge-sensitive amplifier associated with APD or PMT for 511 keV, photon-pair detection

    NASA Astrophysics Data System (ADS)

    Mathez, Hervé; Lu, Guo-Neng; Pittet, Patrick; Quiquerez, Laurent; Russo, Patrice; Lecoq, Jacques; Bohner, Gérard

    2010-01-01

    For positron emission tomography scanners requiring 511 keV two-photon detection, we present a charge-sensitive amplifier (CSA) to be associated with an avalanche photodiode (APD) or photo-multiplier tube (PMT). It is a two-stage structure. The input stage consists of a folded-cascode fully differential circuit and a common-mode feedback (CMFB) circuit. Feedforward technique is implemented to enhance frequency performance. The output stage employs complementary source followers. The amplifier has been designed in a 0.35-μm BiCMOS process with analysis and optimization of noise and speed performances. Testing of fabricated prototypes has given results in good agreement with post-layout simulated ones. The evaluated characteristics of the circuit are: 26 ns peaking time for pulsed stimulus, 2000 electron equivalent input noise charge (ENC) for a detector capacitance up to 80 pF and 136 mW power consumption from a 3.5-V supply.

  5. Improved charge amplifier using hybrid hysteresis compensation

    NASA Astrophysics Data System (ADS)

    Amin-Shahidi, Darya; Trumper, David L.

    2013-08-01

    We present a novel charge amplifier, with a robust feedback circuit and a method for compensating piezoelectric actuator's hysteresis at low frequencies. The amplifier uses a modified feedback circuit which improves robustness to the addition of series load impedance such as in cabling. We also describe a hybrid hysteresis compensation method for enabling the charge amplifier to reduce hysteresis at low frequencies. Experimental results demonstrate the utility of the new amplifier design.

  6. High temperature charge amplifier for geothermal applications

    DOEpatents

    Lindblom, Scott C.; Maldonado, Frank J.; Henfling, Joseph A.

    2015-12-08

    An amplifier circuit in a multi-chip module includes a charge to voltage converter circuit, a voltage amplifier a low pass filter and a voltage to current converter. The charge to voltage converter receives a signal representing an electrical charge and generates a voltage signal proportional to the input signal. The voltage amplifier receives the voltage signal from the charge to voltage converter, then amplifies the voltage signal by the gain factor to output an amplified voltage signal. The lowpass filter passes low frequency components of the amplified voltage signal and attenuates frequency components greater than a cutoff frequency. The voltage to current converter receives the output signal of the lowpass filter and converts the output signal to a current output signal; wherein an amplifier circuit output is selectable between the output signal of the lowpass filter and the current output signal.

  7. Method and apparatus for linear low-frequency feedback in monolithic low-noise charge amplifiers

    DOEpatents

    DeGeronimo, Gianluigi

    2006-02-14

    A charge amplifier includes an amplifier, feedback circuit, and cancellation circuit. The feedback circuit includes a capacitor, inverter, and current mirror. The capacitor is coupled across the signal amplifier, the inverter is coupled to the output of the signal amplifier, and the current mirror is coupled to the input of the signal amplifier. The cancellation circuit is coupled to the output of the signal amplifier. A method of charge amplification includes providing a signal amplifier; coupling a first capacitor across the signal amplifier; coupling an inverter to the output of the signal amplifier; coupling a current mirror to the input of the signal amplifier; and coupling a cancellation circuit to the output of the signal amplifier. A front-end system for use with radiation sensors includes a charge amplifier and a current amplifier, shaping amplifier, baseline stabilizer, discriminator, peak detector, timing detector, and logic circuit coupled to the charge amplifier.

  8. Bolometers - Ultimate sensitivity, optimization, and amplifier coupling

    NASA Technical Reports Server (NTRS)

    Mather, J. C.

    1984-01-01

    Theoretical expressions for Johnson noise and thermal noise in bolometers are considered, and optimization with respect to thermal conductivity and bias power is performed. Numerical approximations are given for the ultimate NEP of bolometers as a function of material parameters and compared with photon noise including photon correlations. A resonating capacitor is shown to improve the coupling to an amplifier, so that the amplifier need not limit performance even for very low temperature bolometers.

  9. Monolithic integrated circuit charge amplifier and comparator for MAMA readout

    NASA Technical Reports Server (NTRS)

    Cole, Edward H.; Smeins, Larry G.

    1991-01-01

    Prototype ICs for the Solar Heliospheric Observatory's Multi-Anode Microchannel Array (MAMA) have been developed; these ICs' charge-amplifier and comparator components were then tested with a view to pulse response and noise performance. All model performance predictions have been exceeded. Electrostatic discharge protection has been included on all IC connections; device operation over temperature has been consistent with model predictions.

  10. Amplified effect of surface charge on cell adhesion by nanostructures

    NASA Astrophysics Data System (ADS)

    Xu, Li-Ping; Meng, Jingxin; Zhang, Shuaitao; Ma, Xinlei; Wang, Shutao

    2016-06-01

    Nano-biointerfaces with varied surface charge can be readily fabricated by integrating a template-based process with maleimide-thiol coupling chemistry. Significantly, nanostructures are employed for amplifying the effect of surface charge on cell adhesion, as revealed by the cell-adhesion performance, cell morphology and corresponding cytoskeletal organization. This study may provide a promising strategy for developing new biomedical materials with tailored cell adhesion for tissue implantation and regeneration.Nano-biointerfaces with varied surface charge can be readily fabricated by integrating a template-based process with maleimide-thiol coupling chemistry. Significantly, nanostructures are employed for amplifying the effect of surface charge on cell adhesion, as revealed by the cell-adhesion performance, cell morphology and corresponding cytoskeletal organization. This study may provide a promising strategy for developing new biomedical materials with tailored cell adhesion for tissue implantation and regeneration. Electronic supplementary information (ESI) available: Experimental details, SEM, KFM AFM, chemical modification and characterization. See DOI: 10.1039/c6nr00649c

  11. Fast Charge Sensing of a Cavity-Coupled Double Quantum Dot Using a Josephson Parametric Amplifier

    NASA Astrophysics Data System (ADS)

    Stehlik, J.; Liu, Y.-Y.; Quintana, C. M.; Eichler, C.; Hartke, T. R.; Petta, J. R.

    2015-07-01

    We demonstrate fast readout of a double quantum dot (DQD) that is coupled to a superconducting resonator. Utilizing a parametric amplifier beyond its range of linear amplification, we improve the signal-to-noise ratio (SNR) by a factor of 2000 compared to the situation with the parametric amplifier turned off. With an integration time of 400 ns comparable to the inverse effective bandwidth, we achieve a SNR of 76. By measuring the SNR as a function of the integration time, we extract an equivalent charge sensitivity of 8 ×10-5 e /√{Hz } . The high SNR allows us to acquire a DQD charge-stability diagram in just 20 ms. At such a high data rate, it is possible to acquire charge-stability diagrams in a live "video mode," enabling real-time tuning of the DQD confinement potential.

  12. Light pulse propagation and charge carrier scattering in semiconductor amplifiers

    SciTech Connect

    Binder, R.; Knorr, A.; Koch, S.W.

    1994-12-31

    The carrier dynamics in inverted semiconductors (optical amplifiers) and light pulse propagations in optical amplifiers have been studied extensively both theoretically and experimentally. Light induced carrier heating processes, which are caused, for example, by two-photon absorption and free carrier absorption, have been studied mainly on the basis of phenomenological models. The full microscopic theory of these processes and their influence on light pulse propagation is still an unsolved problem. Here, the authors present theoretical results on light pulse propagation in inverted semiconductors and semiconductor laser diodes. The theory is based on the semiconductor Maxwell Bloch equations and includes incoherent phenomena due to charge-carrier scattering based on the solution of the appropriate Boltzman equation.

  13. Modelling nanofluidic field amplified sample stacking with inhomogeneous surface charge

    NASA Astrophysics Data System (ADS)

    McCallum, Christopher; Pennathur, Sumita

    2015-11-01

    Nanofluidic technology has exceptional applications as a platform for biological sample preconcentration, which will allow for an effective electronic detection method of low concentration analytes. One such preconcentration method is field amplified sample stacking, a capillary electrophoresis technique that utilizes large concentration differences to generate high electric field gradients, causing the sample of interest to form a narrow, concentrated band. Field amplified sample stacking has been shown to work well at the microscale, with models and experiments confirming expected behavior. However, nanofluidics allows for further concentration enhancement due to focusing of the sample ions toward the channel center by the electric double layer. We have developed a two-dimensional model that can be used for both micro- and nanofluidics, fully accounting for the electric double layer. This model has been used to investigate even more complex physics such as the role of inhomogeneous surface charge.

  14. Raman-Enhanced Phase-Sensitive Fibre Optical Parametric Amplifier

    NASA Astrophysics Data System (ADS)

    Fu, Xuelei; Guo, Xiaojie; Shu, Chester

    2016-02-01

    Phase-sensitive amplification is of great research interest owing to its potential in noiseless amplification. One key feature in a phase-sensitive amplifier is the gain extinction ratio defined as the ratio of the maximum to the minimum gains. It quantifies the capability of the amplifier in performing low-noise amplification for high phase-sensitive gain. Considering a phase-sensitive fibre optical parametric amplifier for linear amplification, the gain extinction ratio increases with the phase-insensitive parametric gain achieved from the same pump. In this work, we use backward Raman amplification to increase the phase-insensitive parametric gain, which in turn improves the phase-sensitive operation. Using a 955 mW Raman pump, the gain extinction ratio is increased by 9.2 dB. The improvement in the maximum phase-sensitive gain is 18.7 dB. This scheme can significantly boost the performance of phase-sensitive amplification in a spectral range where the parametric pump is not sufficiently strong but broadband Raman amplification is available.

  15. Raman-Enhanced Phase-Sensitive Fibre Optical Parametric Amplifier

    PubMed Central

    Fu, Xuelei; Guo, Xiaojie; Shu, Chester

    2016-01-01

    Phase-sensitive amplification is of great research interest owing to its potential in noiseless amplification. One key feature in a phase-sensitive amplifier is the gain extinction ratio defined as the ratio of the maximum to the minimum gains. It quantifies the capability of the amplifier in performing low-noise amplification for high phase-sensitive gain. Considering a phase-sensitive fibre optical parametric amplifier for linear amplification, the gain extinction ratio increases with the phase-insensitive parametric gain achieved from the same pump. In this work, we use backward Raman amplification to increase the phase-insensitive parametric gain, which in turn improves the phase-sensitive operation. Using a 955 mW Raman pump, the gain extinction ratio is increased by 9.2 dB. The improvement in the maximum phase-sensitive gain is 18.7 dB. This scheme can significantly boost the performance of phase-sensitive amplification in a spectral range where the parametric pump is not sufficiently strong but broadband Raman amplification is available. PMID:26830136

  16. Implementation and analysis of an innovative digital charge amplifier for hysteresis reduction in piezoelectric stack actuators

    SciTech Connect

    Bazghaleh, Mohsen Grainger, Steven; Cazzolato, Ben; Lu, Tien-Fu; Oskouei, Reza

    2014-04-15

    Smart actuators are the key components in a variety of nanopositioning applications, such as scanning probe microscopes and atomic force microscopes. Piezoelectric actuators are the most common smart actuators due to their high resolution, low power consumption, and wide operating frequency but they suffer hysteresis which affects linearity. In this paper, an innovative digital charge amplifier is presented to reduce hysteresis in piezoelectric stack actuators. Compared to traditional analog charge drives, experimental results show that the piezoelectric stack actuator driven by the digital charge amplifier has less hysteresis. It is also shown that the voltage drop of the digital charge amplifier is significantly less than the voltage drop of conventional analog charge amplifiers.

  17. Wide bandwidth transimpedance amplifier for extremely high sensitivity continuous measurements

    NASA Astrophysics Data System (ADS)

    Ferrari, Giorgio; Sampietro, Marco

    2007-09-01

    This article presents a wide bandwidth transimpedance amplifier based on the series of an integrator and a differentiator stage, having an additional feedback loop to discharge the standing current from the device under test (DUT) to ensure an unlimited measuring time opportunity when compared to switched discharge configurations while maintaining a large signal amplification over the full bandwidth. The amplifier shows a flat response from 0.6Hzto1.4MHz, the capability to operate with leakage currents from the DUT as high as tens of nanoamperes, and rail-to-rail dynamic range for sinusoidal current signals independent of the DUT leakage current. Also available is a monitor output of the stationary current to track experimental slow drifts. The circuit is ideal for noise spectral and impedance measurements of nanodevices and biomolecules when in the presence of a physiological medium and in all cases where high sensitivity current measurements are requested such as in scanning probe microscopy systems.

  18. Digital filter design with zero shift on charge amplifiers for low shock calibration

    NASA Astrophysics Data System (ADS)

    Nozato, H.; Bruns, T.; Volkers, H.; Oota, A.

    2014-03-01

    Zero shift caused by the low frequency response of charge amplifiers is one of the most significant factors in shock measurements with long duration, such as low shock calibration of accelerometers. In order to reproduce the same zero shift as the charge amplifier, infinite impulse response (IIR) filters were developed by applying a second order transfer function to the high pass characteristic in the low frequency part of the measured frequency response of charge amplifiers. For the experimental verification of the zero shift using the IIR filter, input/output signals of the charge amplifier were investigated by using rectangular waveforms with a peak voltage of 2 V and pulse width of 10 ms and 5 ms, respectively. As indicated by the results, the IIR filter succeeds in following the same zero shift as the charge amplifier.

  19. Privacy-Sensitive Congestion Charging

    NASA Astrophysics Data System (ADS)

    Beresford, Alastair R.; Davies, Jonathan J.; Harle, Robert K.

    National-scale congestion charging schemes are increasingly viewed as the most viable long-term strategy for controlling congestion and maintaining the viability of the road network. In this paper we challenge the widely held belief that enforceable and economically viable congestion charging schemes require drivers to give up their location privacy to the government. Instead we explore an alternative scheme where privately-owned cars enforce congestion charge payments by using an on-board vehicle unit containing a camera and wireless communications. Our solution prevents centralised tracking of vehicle movements but raises an important issue: should we trust our neighbours with a little personal information in preference to entrusting it all to the government?

  20. An Introduction to Phase-Sensitive Amplifiers: An Inexpensive Student Instrument

    ERIC Educational Resources Information Center

    Temple, Paul A.

    1975-01-01

    Discusses the principle of operation of phase-sensitive amplifiers. Gives three examples, suitable for undergraduate laboratory use, of the use of phase-sensitive, or "lock-in" amplifiers. Concludes with a description of an inexpensive lock-in amplifier which has an overall voltage gain of 1000. (Author/MLH)

  1. Wide bandwidth transimpedance amplifier for extremely high sensitivity continuous measurements.

    PubMed

    Ferrari, Giorgio; Sampietro, Marco

    2007-09-01

    This article presents a wide bandwidth transimpedance amplifier based on the series of an integrator and a differentiator stage, having an additional feedback loop to discharge the standing current from the device under test (DUT) to ensure an unlimited measuring time opportunity when compared to switched discharge configurations while maintaining a large signal amplification over the full bandwidth. The amplifier shows a flat response from 0.6 Hz to 1.4 MHz, the capability to operate with leakage currents from the DUT as high as tens of nanoamperes, and rail-to-rail dynamic range for sinusoidal current signals independent of the DUT leakage current. Also available is a monitor output of the stationary current to track experimental slow drifts. The circuit is ideal for noise spectral and impedance measurements of nanodevices and biomolecules when in the presence of a physiological medium and in all cases where high sensitivity current measurements are requested such as in scanning probe microscopy systems. PMID:17902966

  2. An HEMT-Based Cryogenic Charge Amplifier for Sub-kelvin Semiconductor Radiation Detectors

    NASA Astrophysics Data System (ADS)

    Phipps, A.; Sadoulet, B.; Juillard, A.; Jin, Y.

    2016-07-01

    We present the design and noise performance of a fully cryogenic (T=4 K) high-electron mobility transistor (HEMT)-based charge amplifier for readout of sub-kelvin semiconductor radiation detectors. The amplifier is being developed for use in direct detection dark matter searches such as the cryogenic dark matter search and will allow these experiments to probe weakly interacting massive particle masses below 10 GeV/c^2 while retaining background discrimination. The amplifier dissipates ≈ 1 mW of power and provides an open loop voltage gain of several hundreds. The measured noise performance is better than that of JFET-based charge amplifiers and is dominated by the noise of the input HEMT. An optimal filter calculation using the measured closed loop noise and typical detector characteristics predicts a charge resolution of σ _q=106 eV (35 electrons) for leakage currents below 4 × 10^{-15} A.

  3. Active rc filter permits easy trade-off of amplifier gain and sensitivity to gain

    NASA Technical Reports Server (NTRS)

    Kerwin, W. J.; Shaffer, C. V.

    1968-01-01

    Passive RC network was designed with zeros of transmission in the right half of the complex frequency plane in the feedback loop of a simple negative-gain amplifier. The proper positioning provides any desired trade-off between amplifier gain and sensitivity to amplifier gain.

  4. Spacecraft Charging Sensitivity to Material Properties

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Edwards, David L.

    2015-01-01

    Evaluating spacecraft charging behavior of a vehicle in the space environment requires knowledge of the material properties relevant to the charging process. Implementing surface and internal charging models requires a user to specify a number of material electrical properties including electrical resistivity parameters (dark and radiation induced), dielectric constant, secondary electron yields, photoemission yields, and breakdown strength in order to correctly evaluate the electric discharge threat posed by the increasing electric fields generated by the accumulating charge density. In addition, bulk material mass density and/or chemical composition must be known in order to analyze radiation shielding properties when evaluating internal charging. We will first describe the physics of spacecraft charging and show how uncertainties in material properties propagate through spacecraft charging algorithms to impact the results obtained from charging models. We then provide examples using spacecraft charging codes to demonstrate their sensitivity to material properties. The goal of this presentation is to emphasize the importance in having good information on relevant material properties in order to best characterize on orbit charging threats.

  5. Low threshold amplified spontaneous emission and ambipolar charge transport in non-volatile liquid fluorene derivatives.

    PubMed

    Ribierre, Jean-Charles; Zhao, Li; Inoue, Munetomo; Schwartz, Pierre-Olivier; Kim, Ju-Hyung; Yoshida, Kou; Sandanayaka, Atula S D; Nakanotani, Hajime; Mager, Loic; Méry, Stéphane; Adachi, Chihaya

    2016-02-21

    Highly fluorescent non-volatile fluidic fluorene derivatives functionalized with siloxane chains were synthesized and used in monolithic solvent-free liquid organic semiconductor distributed feedback lasers. The photoluminescence quantum yield values, the amplified spontaneous emission thresholds and the ambipolar charge carrier mobilities demonstrate that this class of materials is extremely promising for organic fluidic light-emitting and lasing devices. PMID:26734693

  6. Position Sensitive Detection System for Charged Particles

    SciTech Connect

    Coello, E. A.; Favela, F.; Curiel, Q.; Chavez, E; Huerta, A.; Varela, A.; Shapira, Dan

    2012-01-01

    The position sensitive detection system presented in this work employs the Anger logic algorithm to determine the position of the light spark produced by the passage of charged particles on a 170 x 170 x 10 mm3 scintillator material (PILOT-U). The detection system consists of a matrix of nine photomultipliers, covering a fraction of the back area of the scintillators. Tests made with a non-collimated alpha particle source together with a Monte Carlo simulation that reproduces the data, suggest an intrinsic position resolution of up to 6 mm is achieved.

  7. Wiggler taper optimization for free-electron-laser amplifiers with moderate space-charge effects

    SciTech Connect

    Jong, R.A.; Scharlemann, E.T.; Fawley, W.M.

    1987-01-01

    The standard synchronous tapering method used to design the wiggler magnetic field for free-electron-laser (FEL) amplifiers operating in the Compton regime will not work for amplifier systems where space-charge effects are important. The space-charge effects lower the overall gain in the amplifier system and, even more importantly, shift the peak in the gain curve to magnetic field values that are significantly less than the synchronous magnetic field value. As a result, the overall predicted gain using the synchronous tapering method is too low. Moreover, the synchronous magnetic field corresponds to the peak in the gain curve for a frequency below the fundamental frequency. Consequently, shot noise at frequencies below the fundamental frequency can grow to levels that may prevent amplification of the fundamental. We have developed a new tapering strategy that improves the predicted amplifier gain and circumvents the shot-noise growth for systems with moderate space-charge effects. For this new strategy, we hold the wiggler magnetic field constant at a value below the synchronous value but near the peak of the gain curve for the fundamental frequency, for some optimized length at the front end of the wiggler. Beyond this constant wiggler section, the field is tapered using the standrd synchronous tapering algorithm. This new tapering scheme results in significant improvement in predicted amplifier gains and limits the growth of shot noise to insignificant levels. We demonstrate the effectiveness of this new tapering algorithm using the tapered wiggler design for the proposed microwave heating experiment (MTX) at the Lawrence Livermore National Laboratory (LLNL). 4 refs., 8 figs.

  8. Simulation of Cascaded Longitudinal-Space-Charge Amplifier at the Fermilab Accelerator Science & Technology (Fast) Facility

    SciTech Connect

    Halavanau, A.; Piot, P.

    2015-12-01

    Cascaded Longitudinal Space Charge Amplifiers (LSCA) have been proposed as a mechanism to generate density modulation over a board spectral range. The scheme has been recently demonstrated in the optical regime and has confirmed the production of broadband optical radiation. In this paper we investigate, via numerical simulations, the performance of a cascaded LSCA beamline at the Fermilab Accelerator Science & Technology (FAST) facility to produce broadband ultraviolet radiation. Our studies are carried out using elegant with included tree-based grid-less space charge algorithm.

  9. Simulation of a cascaded longitudinal space charge amplifier for broadband radiation production using a superconducting linac

    SciTech Connect

    Halavanau, A.; Piot, P.

    2015-10-02

    Longitudinal space charge (LSC) effects are generally considered as harmful in free-electron lasers as they can seed unfavorable energy modulations that can result in density modulations with associated emittance dilution. It was pointed out, however, that such \\micro-bunching instabilities" could be potentially useful to support the generation of broadband coherent radiation. Therefore there has been an increasing interest in devising accelerator beam lines capable of controlling LSC induced density modulations. In the present paper we augment these previous investigations by combining a grid-less space charge algorithm with the popular particle-tracking program elegant. This high-fidelity model of the space charge is used to benchmark conventional LSC models. We then employ the developed model to optimize the performance of a cascaded longitudinal space charge amplifier using beam parameters comparable to the ones achievable at Fermilab Accelerator Science & Technology (FAST) facility currently under commissioning at Fermilab

  10. Simulation of a cascaded longitudinal space charge amplifier for coherent radiation generation

    DOE PAGESBeta

    Halavanau, A.; Piot, P.

    2016-03-03

    Longitudinal space charge (LSC) effects are generally considered as harmful in free-electron lasers as they can seed unfavorable energy modulations that can result in density modulations with associated emittance dilution. It was pointed out, however, that such \\micro-bunching instabilities" could be potentially useful to support the generation of broadband coherent radiation. Therefore there has been an increasing interest in devising accelerator beam lines capable of controlling LSC induced density modulations. In the present paper we augment these previous investigations by combining a grid-less space charge algorithm with the popular particle-tracking program elegant. This high-fidelity model of the space charge ismore » used to benchmark conventional LSC models. We then employ the developed model to optimize the performance of a cascaded longitudinal space charge amplifier using beam parameters comparable to the ones achievable at Fermilab Accelerator Science & Technology (FAST) facility currently under commissioning at Fermilab.« less

  11. Mass amplifying probe for sensitive fluorescence anisotropy detection of small molecules in complex biological samples.

    PubMed

    Cui, Liang; Zou, Yuan; Lin, Ninghang; Zhu, Zhi; Jenkins, Gareth; Yang, Chaoyong James

    2012-07-01

    Fluorescence anisotropy (FA) is a reliable and excellent choice for fluorescence sensing. One of the key factors influencing the FA value for any molecule is the molar mass of the molecule being measured. As a result, the FA method with functional nucleic acid aptamers has been limited to macromolecules such as proteins and is generally not applicable for the analysis of small molecules because their molecular masses are relatively too small to produce observable FA value changes. We report here a molecular mass amplifying strategy to construct anisotropy aptamer probes for small molecules. The probe is designed in such a way that only when a target molecule binds to the probe does it activate its binding ability to an anisotropy amplifier (a high molecular mass molecule such as protein), thus significantly increasing the molecular mass and FA value of the probe/target complex. Specifically, a mass amplifying probe (MAP) consists of a targeting aptamer domain against a target molecule and molecular mass amplifying aptamer domain for the amplifier protein. The probe is initially rendered inactive by a small blocking strand partially complementary to both target aptamer and amplifier protein aptamer so that the mass amplifying aptamer domain would not bind to the amplifier protein unless the probe has been activated by the target. In this way, we prepared two probes that constitute a target (ATP and cocaine respectively) aptamer, a thrombin (as the mass amplifier) aptamer, and a fluorophore. Both probes worked well against their corresponding small molecule targets, and the detection limits for ATP and cocaine were 0.5 μM and 0.8 μM, respectively. More importantly, because FA is less affected by environmental interferences, ATP in cell media and cocaine in urine were directly detected without any tedious sample pretreatment. Our results established that our molecular mass amplifying strategy can be used to design aptamer probes for rapid, sensitive, and selective

  12. Investigation of Charge Gain in Diamond Electron Beam Amplifiers Via 3D Simulations

    SciTech Connect

    Busby,R.; Rao,T.; D.A. Dimitrov, J.R. Cary, I. Ben-Zvi, X. Chang, J. Keister, E. Muller, J. Smedley, Q. Wu

    2009-05-04

    A promising new concept of a diamond amplified photocathode for generation of high-current, high-brightness, and low thermal emittance electron beams was recently proposed and is currently under active development. To better understand the different effects involved in the generation ofelectron beams from diamond, we have been developing models (within the VORPAL computational framework) to simulate secondary electron generation and charge transport. The currently implemented models include inelastic scattering of electrons and holes for generation of electron-hole pairs, elastic, phonon, and charge impurity scattering. We will present results from 3D VORPAL simulations with these capabilities on charge gain as a function of primary electron energy and applied electric field. Moreover, we consider effects of electron and hole cloud expansion (initiated by primary electrons) and separation in a surface domain of diamond.

  13. Simulation of a cascaded longitudinal space charge amplifier for coherent radiation generation

    NASA Astrophysics Data System (ADS)

    Halavanau, A.; Piot, P.

    2016-05-01

    Longitudinal space charge (LSC) effects are generally considered as harmful in free-electron lasers as they can seed unfavorable energy modulations that can result in density modulations with associated emittance dilution. This "micro-bunching instabilities" is naturally broadband and could possibly support the generation of coherent radiation over a broad region of the spectrum. Therefore there has been an increasing interest in devising accelerator beam lines capable of controlling LSC induced density modulations. In the present paper we refine these previous investigations by combining a grid-less space charge algorithm with the popular particle-tracking program ELEGANT. This high-fidelity model of the space charge is used to benchmark conventional LSC models. We finally employ the developed model to investigate the performance of a cascaded LSC amplifier using beam parameters comparable to the ones achievable at Fermilab Accelerator Science & Technology (FAST) facility currently under commissioning at Fermilab.

  14. Improvement in the sensitivity of microfluidic ELISA through field amplified stacking of the enzyme reaction product.

    PubMed

    Giri, Basant; Dutta, Debashis

    2014-01-31

    In this article, we demonstrate a novel approach to enhancing the sensitivity of enzyme-linked immunosorbent assays (ELISA) through pre-concentration of the enzyme reaction product (resorufin/4-methylumbelliferone) in free solution. The reported pre-concentration was accomplished by transporting the resorufin/4-methylumbelliferone molecules produced in the ELISA process towards a high ionic-strength buffer stream in a microfluidic channel while applying a voltage drop across this merging region. A sharp change in the electric field around the junction of the two liquid streams was observed to abruptly slow down the negatively charged resorufin/4-methylumbelliferone species leading to the reported pre-concentration effect based on the field amplified stacking (FAS) technique. It has been shown that the resulting enhancement in the detectability of the enzyme reaction product significantly improves the signal-to-noise ratio in the system thereby reducing the smallest detectable analyte concentration in the ELISA method. Applying the above-described approach, we were able to detect mouse anti-BSA and human TNF-α at concentrations nearly 60-fold smaller than that possible on commercial microwell plates. For the human TNF-α sample, this improvement in assay sensitivity corresponded to a limit of detection (LOD) of 0.102pg mL(-1) using the FAS based microfluidic ELISA method as compared to 7.03pg mL(-1) obtained with the traditional microwell plate based approach. Moreover, because our ELISAs were performed in micrometer sized channels, they required sample volumes about two orders of magnitude smaller than that consumed in the latter case (1μL versus 100μL). PMID:24439502

  15. Nonlinear phase noise mitigation in phase-sensitive amplified transmission systems.

    PubMed

    Olsson, Samuel L I; Karlsson, Magnus; Andrekson, Peter A

    2015-05-01

    We investigate the impact of in-line amplifier noise in transmission systems amplified by two-mode phase-sensitive amplifiers (PSAs) and present the first experimental demonstration of nonlinear phase noise (NLPN) mitigation in a modulation format independent PSA-amplified transmission system. The NLPN mitigation capability is attributed to the correlated noise on the signal and idler waves at the input of the transmission span. We study a single-span system with noise loading in the transmitter but the results are expected to be applicable also in multi-span systems. The experimental investigation is supported by numerical simulations showing excellent agreement with the experiments. In addition to demonstrating NLPN mitigation we also present a record high sensitivity receiver, enabled by low-noise PSA-amplification, requiring only 4.1 photons per bit to obtain a bit error ratio (BER) of 1 × 10(-3) with 10 GBd quadrature phase-shift keying (QPSK) data. PMID:25969263

  16. A dual mode charge pump with adaptive output used in a class G audio power amplifier

    NASA Astrophysics Data System (ADS)

    Yong, Feng; Zhenfei, Peng; Shanshan, Yang; Zhiliang, Hong; Yang, Liu

    2011-04-01

    A dual mode charge pump to produce an adaptive power supply for a class G audio power amplifier is presented. According to the amplitude of the input signals, the charge pump has two level output voltage rails available to save power. It operates both in current mode at high output load and in pulse frequency modulation (PFM) at light load to reduce the power dissipation. Also, dynamic adjustment of the power stage transistor size based on load current at the PFM mode is introduced to reduce the output voltage ripple and prevent the switching frequency from audio range. The prototype is implemented in 0.18 μm 3.3 V CMOS technology. Experimental results show that the maximum power efficiency of the charge pump is 79.5% @ 0.5x mode and 83.6% @ 1x mode. The output voltage ripple is less than 15 mV while providing 120 mA of the load current at PFM control and less than 18 mV while providing 300 mA of the load current at current mode control. An analytical model for ripple voltage and efficiency calculation of the proposed PFM control demonstrates reasonable agreement with measured results.

  17. Injection locking-based pump recovery for phase-sensitive amplified links.

    PubMed

    Olsson, Samuel L I; Corcoran, Bill; Lundström, Carl; Tipsuwannakul, Ekawit; Sygletos, Stylianos; Ellis, Andrew D; Tong, Zhi; Karlsson, Magnus; Andrekson, Peter A

    2013-06-17

    An injection locking-based pump recovery system for phase-sensitive amplified links, capable of handling 40 dB effective span loss, is demonstrated. Measurements with 10 GBd DQPSK signals show penalty-free recovery of a pump wave, phase modulated with two sinusoidal RF-tones at 0.1 GHz and 0.3 GHz, with 64 dB amplification. The operating power limit for the pump recovery system is experimentally investigated and is governed by the noise transfer and phase modulation transfer characteristics of the injection-locked laser. The corresponding link penalties are explained and quantified. This system enables, for the first time, WDM compatible phase-sensitive amplified links over significant lengths. PMID:23787639

  18. Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers.

    PubMed

    Sorokina, Mariia; Sygletos, Stylianos; Ellis, Andrew D; Turitsyn, Sergei

    2013-12-16

    We investigate the transmission performance of advanced modulation formats in nonlinear regenerative channels based on cascaded phase sensitive amplifiers. We identify the impact of amplitude and phase noise dynamics along the transmission line and show that after a cascade of regenerators, densely packed single ring PSK constellations outperform multi-ring constellations. The results of this study will greatly simplify the design of future nonlinear regenerative channels for ultra-high capacity transmission. PMID:24514694

  19. Frequency-resolved noise figure measurements of phase (in)sensitive fiber optical parametric amplifiers.

    PubMed

    Malik, R; Kumpera, A; Lorences-Riesgo, A; Andrekson, P A; Karlsson, M

    2014-11-17

    We measure the frequency-resolved noise figure of fiber optical parametric amplifiers both in phase-insensitive and phase-sensitive modes in the frequency range from 0.03 to 3 GHz. We also measure the variation in noise figure due to the degradation in pump optical signal to noise ratio and also as a function of the input signal powers. Noise figure degradation due to stimulated Brillouin scattering is observed. PMID:25402025

  20. Stability of pulses on optical fibers with phase-sensitive amplifiers

    NASA Astrophysics Data System (ADS)

    Alexander, J. C.; Grillakis, M. G.; Jones, C. K. R. T.; Sandstede, B.

    Pulse stability is crucial to the effective propagation of information in a soliton-based optical communication system. It is shown in this paper that pulses in optical fibers, for which attenuation is compensated by phase-sensitive amplifiers, are stable over a large range of parameter values. A fourth-order nonlinear diffusion model due to Kutz and co-workers is used. The stability proof invokes a number of mathematical techniques, including the Evans function and Grillakis' functional analytic approach.

  1. Shot noise limit of sensitivity of chemically amplified resists used for extreme ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Fujii, Shinya; Kozawa, Takahiro; Okamoto, Kazumasa; Santillan, Julius Joseph; Itani, Toshiro

    2015-11-01

    With the improvement of resolution, the shot noise effect becomes a serious concern in the lithography used for high-volume production of semiconductor devices. In this study, the shot noise limit of the sensitivity of chemically amplified resists was investigated from the viewpoint of sensitivity enhancement, assuming extreme ultraviolet lithography. The latent images of line-and-space patterns with 11 nm half-pitch were calculated using a Monte Carlo method. The effect of secondary electron blur was eliminated to clarify the shot noise limit of line edge roughness (LER). When the requirement for line width roughness (LWR) was assumed to be 10% critical dimension (CD), the shot noise limit of sensitivity was >100 mJ cm-2. For the 20% CD LWR, the shot noise limits of sensitivity for the 10, 20, and 30 wt % acid generator concentrations were 20, 9, and 7 mJ cm-2, respectively.

  2. Mitigation of nonlinear distortion in hybrid Raman/phase-sensitive amplifier links.

    PubMed

    Eliasson, Henrik; Olsson, Samuel L I; Karlsson, Magnus; Andrekson, Peter A

    2016-01-25

    Hybrid systems combining distributed Raman amplification and phase-sensitive amplifiers (PSAs) are investigated in numerical simulations. We focus on the mitigation of fiber nonlinearities and the impact of the span power map which is also important in systems employing optical phase conjugation or phase-conjugated twin waves. We simulate multi-span PSA links with and without distributed Raman amplification and show that by including distributed Raman amplification, the transmission distance increases more at optimum launch power than in the linear regime. For a 5-channel WDM QPSK PSA-amplified system, we observe a transmission reach increase by a factor of 8.1 by including ideal distributed Raman amplification. PMID:26832472

  3. Experimental implementation of a nonlinear beamsplitter based on a phase-sensitive parametric amplifier

    NASA Astrophysics Data System (ADS)

    Fang, Yami; Feng, Jingliang; Cao, Leiming; Wang, Yaxian; Jing, Jietai

    2016-03-01

    Beamsplitters have played an important role in quantum optics experiments. They are often used to split and combine two beams, especially in the construct of an interferometer. In this letter, we experimentally implement a nonlinear beamsplitter using a phase-sensitive parametric amplifier, which is based on four-wave mixing in hot rubidium vapor. Here we show that, despite the different frequencies of the two input beams, the output ports of the nonlinear beamsplitter exhibit interference phenomena. We make measurements of the interference fringe visibility and study how various parameters, such as the intensity gain of the amplifier, the intensity ratio of the two input beams, and the one and two photon detunings, affect the behavior of the nonlinear beamsplitter. It may find potential applications in quantum metrology and quantum information processing.

  4. Numerical Investigation of a Cascaded Longitudinal Space-Charge Amplifier at the Fermilab's Advanced Superconducting Test Accelerator

    SciTech Connect

    Halavanau, A.; Piot, P.

    2015-06-01

    In a cascaded longitudinal space-charge amplifier (LSCA), initial density noise in a relativistic e-beam is amplified via the interplay of longitudinal space charge forces and properly located dispersive sections. This type of amplification process was shown to potentially result in large final density modulations [1] compatible with the production of broadband electromagnetic radiation. The technique was recently demonstrated in the optical domain [2]. In this paper we investigate, via numerical simulations, the performances of a cascaded LSCA beamline at the Fermilab’s Advanced Superconducting Test Accelerator (ASTA). We especially explore the properties of the produced broadband radiation. Our studies have been conducted with a grid-less three-dimensional space-charge algorithm.

  5. Sensitive electrochemical assaying of DNA methyltransferase activity based on mimic-hybridization chain reaction amplified strategy.

    PubMed

    Zhang, Linqun; Liu, Yuanjian; Li, Ying; Zhao, Yuewu; Wei, Wei; Liu, Songqin

    2016-08-24

    A mimic-hybridization chain reaction (mimic-HCR) amplified strategy was proposed for sensitive electrochemically detection of DNA methylation and methyltransferase (MTase) activity In the presence of methylated DNA, DNA-gold nanoparticles (DNA-AuNPs) were captured on the electrode by sandwich-type assembly. It then triggered mimic-HCR of two hairpin probes to produce many long double-helix chains for numerous hexaammineruthenium (III) chloride ([Ru(NH3)6](3+), RuHex) inserting. As a result, the signal for electrochemically detection of DNA MTase activity could be amplified. If DNA was non-methylated, however, the sandwich-type assembly would not form because the short double-stranded DNAs (dsDNA) on the Au electrode could be cleaved and digested by restriction endonuclease HpaII (HapII) and exonuclease III (Exo III), resulting in the signal decrement. Based on this, an electrochemical approach for detection of M.SssI MTase activity with high sensitivity was developed. The linear range for M.SssI MTase activity was from 0.05 U mL(-1) to 10 U mL(-1), with a detection limit down to 0.03 U mL(-1). Moreover, this detecting strategy held great promise as an easy-to-use and highly sensitive method for other MTase activity and inhibition detection by exchanging the corresponding DNA sequence. PMID:27496999

  6. Decoherence of odd compass states in the phase-sensitive amplifying/dissipating environment

    NASA Astrophysics Data System (ADS)

    Dodonov, V. V.; Valverde, C.; Souza, L. S.; Baseia, B.

    2016-08-01

    We study the evolution of odd compass states (specific superpositions of four coherent states), governed by the standard master equation with phase-sensitive amplifying/attenuating terms, in the presence of a Hamiltonian describing a parametric degenerate linear amplifier. Explicit expressions for the time-dependent Wigner function are obtained. The time of disappearance of the so called "sub-Planck structures" is calculated using the negative value of the Wigner function at the origin of phase space. It is shown that this value rapidly decreases during a short "conventional interference degradation time" (CIDT), which is inversely proportional to the size of quantum superposition, provided the anti-Hermitian terms in the master equation are of the same order (or stronger) as the Hermitian ones (governing the parametric amplification). The CIDT is compared with the final positivization time (FPT), when the Wigner function becomes positive. It appears that the FPT does not depend on the size of superpositions, moreover, it can be much bigger in the amplifying media than in the attenuating ones. Paradoxically, strengthening the Hamiltonian part results in decreasing the CIDT, so that the CIDT almost does not depend on the size of superpositions in the asymptotical case of very weak reservoir coupling. We also analyze the evolution of the Mandel factor, showing that for some sets of parameters this factor remains significantly negative, even when the Wigner function becomes positive.

  7. Highly sensitive beam quality measurements on large-mode-area fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Weßels, Peter; Fallnich, Carsten

    2003-12-01

    The beam quality of large-mode-area fiber amplifiers was investigated at the 10 W power level using a tunable ring cavity, that is also used in the laboratory system of GEO600 as a pre-mode-cleaner for mode filtering. More than 98% of the overall output power were contained within the polarized (200:1) TEM00 mode with an appropriate choice of coiling diameter. With the high sensitivity ring cavity analysis, the beam quality improvement caused by decreasing the coiling diameter was verified, while this could not be seen within conventional M2-measurements. The results are compared with the properties of single-mode fibers.

  8. Highly sensitive beam quality measurements on large-mode-area fiber amplifiers.

    PubMed

    Weßels, Peter; Fallnich, Carsten

    2003-12-15

    The beam quality of large-mode-area fiber amplifiers was investigated at the 10 W power level using a tunable ring cavity, that is also used in the laboratory system of GEO600 as a pre-mode-cleaner for mode filtering. More than 98% of the overall output power were contained within the polarized (200:1) TEM00 mode with an appropriate choice of coiling diameter. With the high sensitivity ring cavity analysis, the beam quality improvement caused by decreasing the coiling diameter was verified, while this could not be seen within conventional M2-measurements. The results are compared with the properties of single-mode fibers. PMID:19471464

  9. Fast and sensitive detection of an oscillating charge

    SciTech Connect

    Bian, X.; Hasko, D. G.; Milne, W. I.

    2015-07-13

    We investigate the high-frequency operation of a percolation field effect transistor to monitor microwave excited single trapped charge. Readout is accomplished by measuring the effect of the polarization field associated with the oscillating charge on the AC signal generated in the channel due to charge pumping. This approach is sensitive to the relative phase between the polarization field and the pumped current, which is different from the conventional approach relying on the amplitude only. Therefore, despite the very small influence of the single oscillating trapped electron, a large signal can be detected. Experimental results show large improvement in both signal-to-noise ratio and measurement bandwidth.

  10. Optimization of the alignment sensitivity and energy stability of the NIF regenerative amplifier cavity/011

    SciTech Connect

    Hopps, N. W., Atomic Weapons Research Establishment, Aldermaston, Great Britain

    1998-06-24

    The work to improve the energy stability of the regenerative amplifier (`regen`) for the National Ignition Facility is described. This includes a fast feed-forward system, designed to regulate the output energy of the regen by monitoring how quickly a pulse builds up over many round trips. Shot-to-shot energy fluctuations of all elements prior to (and including) the regen may be compensated for in this way, at the expense of a loss of approximately 50%. Also included is a detailed study into the alignment sensitivity of the regen cavity, with the goal of quantifying the effect of misalignment on the output energy. This is done by calculating the displacement of the eigenmode by augmenting the cavity ABCD matrix with the misalignment matrix elements, E, F. In this way, cavity misalignment issues due to thermal loading of the gain medium are investigated. Alternative cavity designs, which reduce the alignment sensitivity and therefore the energy drift over periods of continuous operation, are considered. Alterations to the amplifier head design are also considered.

  11. Optimization of the alignment sensitivity and energy stability of the NIF regenerative amplifier cavity

    NASA Astrophysics Data System (ADS)

    Hopps, N. W.; Wilcox, Russell B.; Hermann, Mark R.; Martinez, Mikael D.; Padilla, Ernesto H.; Crane, John K.

    1999-07-01

    The work to improve the energy stability of the regenerative amplifier for the NIF is described. This includes a fast feed-forward system, designed to regulate the output energy of the regen by monitoring how quickly a pulse builds up over many round trips. Shot-to-shot energy fluctuations of all elements prior to the regen may be compensated for in this way, at the expense of a loss of approximately 50 percent. Also included is a detailed study into the alignment sensitivity of the regen cavity, with the goal of quantifying the effect of misalignment on the output energy. This is done by calculating the displacement of the eigenmode by augmenting the cavity ABCD matrix with the misalignment matrix elements, E, F. In this way, cavity misalignment issues due to thermal loading of the gain medium are investigated. Alternative cavity designs, which reduce the alignment sensitivity and therefore the energy drift over periods of continuous operation, are considered. Alterations to the amplifier head design are also considered.

  12. Dual amplified electrochemical immunosensor for highly sensitive detection of Pantoea stewartii sbusp. stewartii.

    PubMed

    Zhao, Yuan; Liu, Liqiang; Kong, Dezhao; Kuang, Hua; Wang, Libing; Xu, Chuanlai

    2014-12-10

    Accurate and highly sensitive detection of Pantoea stewartii sbusp. stewartii-NCPPB 449 (PSS) is urgently required for international shipments due to tremendous agricultural economic losses. Herein, a dual amplified electrochemical sandwich immunosensor for PSS detection was developed, utilizing the good specificity and low cost of electrochemical immunoassay, the favorable conductivity and large specific surface area of gold nanoparticles (Au NPs), and the excellent catalytic ability of and horseradish peroxidase (HRP). A linear curve between current response and PSS concentration was established, and the limit of detection (LOD) was 7.8 × 10(3) cfu/mL, which is 20 times lower than that for conventional enzyme-linked immunosorbent assay (ELISA). This strategy is a useful approach for the highly sensitive detection of plant pathogenic bacterium. PMID:25384268

  13. Effect of input phase modulation to a phase-sensitive optical amplifier.

    PubMed

    Li, Tian; Anderson, Brian E; Horrom, Travis; Jones, Kevin M; Lett, Paul D

    2016-08-22

    Many optical applications depend on amplitude modulating optical beams using devices such as acousto-optical modulators (AOMs) or optical choppers. Methods to add amplitude modulation (AM) often inadvertently impart phase modulation (PM) onto the light as well. While this PM is of no consequence to many phase-insensitive applications, phase-sensitive processes can be affected. Here we study the effects of input phase and amplitude modulation on the output of a quantum-noise limited phase-sensitive optical amplifier (PSA) realized in hot 85Rb vapor. We investigate the dependence of PM on AOM alignment and demonstrate a novel approach to quantifying PM by using the PSA as a diagnostic tool. We then use this method to measure the alignment-dependent PM of an optical chopper which arises due to diffraction effects as the chopper blade passes through the optical beam. PMID:27557263

  14. Sensitivity enhancement in swept-source optical coherence tomography by parametric balanced detector and amplifier

    PubMed Central

    Kang, Jiqiang; Wei, Xiaoming; Li, Bowen; Wang, Xie; Yu, Luoqin; Tan, Sisi; Jinata, Chandra; Wong, Kenneth K. Y.

    2016-01-01

    We proposed a sensitivity enhancement method of the interference-based signal detection approach and applied it on a swept-source optical coherence tomography (SS-OCT) system through all-fiber optical parametric amplifier (FOPA) and parametric balanced detector (BD). The parametric BD was realized by combining the signal and phase conjugated idler band that was newly-generated through FOPA, and specifically by superimposing these two bands at a photodetector. The sensitivity enhancement by FOPA and parametric BD in SS-OCT were demonstrated experimentally. The results show that SS-OCT with FOPA and SS-OCT with parametric BD can provide more than 9 dB and 12 dB sensitivity improvement, respectively, when compared with the conventional SS-OCT in a spectral bandwidth spanning over 76 nm. To further verify and elaborate their sensitivity enhancement, a bio-sample imaging experiment was conducted on loach eyes by conventional SS-OCT setup, SS-OCT with FOPA and parametric BD at different illumination power levels. All these results proved that using FOPA and parametric BD could improve the sensitivity significantly in SS-OCT systems. PMID:27446655

  15. Sensitivity enhancement in swept-source optical coherence tomography by parametric balanced detector and amplifier.

    PubMed

    Kang, Jiqiang; Wei, Xiaoming; Li, Bowen; Wang, Xie; Yu, Luoqin; Tan, Sisi; Jinata, Chandra; Wong, Kenneth K Y

    2016-04-01

    We proposed a sensitivity enhancement method of the interference-based signal detection approach and applied it on a swept-source optical coherence tomography (SS-OCT) system through all-fiber optical parametric amplifier (FOPA) and parametric balanced detector (BD). The parametric BD was realized by combining the signal and phase conjugated idler band that was newly-generated through FOPA, and specifically by superimposing these two bands at a photodetector. The sensitivity enhancement by FOPA and parametric BD in SS-OCT were demonstrated experimentally. The results show that SS-OCT with FOPA and SS-OCT with parametric BD can provide more than 9 dB and 12 dB sensitivity improvement, respectively, when compared with the conventional SS-OCT in a spectral bandwidth spanning over 76 nm. To further verify and elaborate their sensitivity enhancement, a bio-sample imaging experiment was conducted on loach eyes by conventional SS-OCT setup, SS-OCT with FOPA and parametric BD at different illumination power levels. All these results proved that using FOPA and parametric BD could improve the sensitivity significantly in SS-OCT systems. PMID:27446655

  16. Charge integration successive approximation analog-to-digital converter for focal plane applications using a single amplifier

    NASA Technical Reports Server (NTRS)

    Zhou, Zhimin (Inventor); Pain, Bedabrata (Inventor)

    1999-01-01

    An analog-to-digital converter for on-chip focal-plane image sensor applications. The analog-to-digital converter utilizes a single charge integrating amplifier in a charge balancing architecture to implement successive approximation analog-to-digital conversion. This design requires minimal chip area and has high speed and low power dissipation for operation in the 2-10 bit range. The invention is particularly well suited to CMOS on-chip applications requiring many analog-to-digital converters, such as column-parallel focal-plane architectures.

  17. Quantum correlations of an entangled state propagating through a phase-sensitive amplifier

    NASA Astrophysics Data System (ADS)

    Li, Tian; Anderson, Brian; Horrom, Travis; Glasser, Ryan; Jones, Kevin; Lett, Paul

    2015-05-01

    We investigate the advance and delay of information transmitted through an optical phase-sensitive amplifier (PSA). We start with a two-mode entangled state created by four-wave mixing in hot 85Rb vapor and measure the mutual information shared by the two modes. We then pass one of these two modes through a PSA and investigate the shift of the mutual information as a function of the PSA phase. The cross-correlation between the two modes of a bipartite EPR state can be advanced by propagation through a fast-light medium and, the extra noise added by a phase-insensitive amplifier has been shown to limit the advance of entanglement, preventing the mutual information from traveling superluminally. In the case of a PSA, however, it is well known that no extra noise will be added for the correct PSA phase (e.g. at the maximal amplification and the maximal deamplification). It is therefore of interest to examine the behavior of the dispersion and the mutual information when passing a signal through a PSA operated at different phases. The behavior of other correlation measures like the quantum discord will be presented as well. Based upon work supported by AFOSR and NSF (PFC at JQI).

  18. Sensitivity enhancement of chemically amplified resists and performance study using EUV interference lithography

    NASA Astrophysics Data System (ADS)

    Buitrago, Elizabeth; Nagahara, Seiji; Yildirim, Oktay; Nakagawa, Hisashi; Tagawa, Seiichi; Meeuwissen, Marieke; Nagai, Tomoki; Naruoka, Takehiko; Verspaget, Coen; Hoefnagels, Rik; Rispens, Gijsbert; Shiraishi, Gosuke; Terashita, Yuichi; Minekawa, Yukie; Yoshihara, Kosuke; Oshima, Akihiro; Vockenhuber, Michaela; Ekinci, Yasin

    2016-03-01

    Extreme ultraviolet lithography (EUVL, λ = 13.5 nm) is the most promising candidate to manufacture electronic devices for future technology nodes in the semiconductor industry. Nonetheless, EUVL still faces many technological challenges as it moves toward high-volume manufacturing (HVM). A key bottleneck from the tool design and performance point of view has been the development of an efficient, high power EUV light source for high throughput production. Consequently, there has been extensive research on different methodologies to enhance EUV resist sensitivity. Resist performance is measured in terms of its ultimate printing resolution, line width roughness (LWR), sensitivity (S or best energy BE) and exposure latitude (EL). However, there are well-known fundamental trade-off relationships (LRS trade-off) among these parameters for chemically amplified resists (CARs). Here we present early proof-of-principle results for a multi-exposure lithography process that has the potential for high sensitivity enhancement without compromising other important performance characteristics by the use of a Photosensitized Chemically Amplified Resist (PSCAR). With this method, we seek to increase the sensitivity by combining a first EUV pattern exposure with a second UV flood exposure (λ = 365 nm) and the use of a PSCAR. In addition, we have evaluated over 50 different state-of-the-art EUV CARs. Among these, we have identified several promising candidates that simultaneously meet sensitivity, LWR and EL high performance requirements with the aim of resolving line space (L/S) features for the 7 and 5 nm logic node (16 nm and 13 nm half-pitch HP, respectively) for HVM. Several CARs were additionally found to be well resolved down to 12 nm and 11 nm HP with minimal pattern collapse and bridging, a remarkable feat for CARs. Finally, the performance of two negative tone state-of-the-art alternative resist platforms previously investigated was compared to the CAR performance at and

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Existence and stability of N-pulses on optical fibers with phase-sensitive amplifiers

    NASA Astrophysics Data System (ADS)

    Sandstede, B.; Jones, C. K. R. T.; Alexander, J. C.

    1997-02-01

    The propagation of pulses in optical communication systems in which attenuation is compensated by phase-sensitive amplifiers is investigated. A central issue is whether optical fibers are capable of carrying several pieces of information at the same time. In this paper, multiple pulses are shown to exist for a fourth-order nonlinear diffusion model due to Kutz and co-workers (1994). Moreover, criteria are derived for determining which of these pulses are stable. The pulses arise in a reversible orbit-flip, a homoclinic bifurcation investigated here for the first time. Numerical simulations are used to study multiple pulses far away from the actual bifurcation point. They confirm that properties of the multiple pulses including their stability are surprisingly well-predicted by the analysis carried out near the bifurcation.

  1. Asymmetric MQW semiconductor optical amplifier with low-polarization sensitivity of over 90-nm bandwidth

    NASA Astrophysics Data System (ADS)

    Nkanta, Julie E.; Maldonado-Basilio, Ramón; Abdul-Majid, Sawsan; Zhang, Jessica; Hall, Trevor J.

    2013-12-01

    An exhausted capacity of current Passive Optical Networks has been anticipated as bandwidth-hungry applications such as HDTV and 3D video become available to end-users. To enhance their performance, the next generation optical access networks have been proposed, using optical carriers allocated within the E-band (1360-1460 nm). It is partly motivated by the low-water peak fiber being manufactured by Corning. At these wavelengths, choices for low cost optical amplifiers, with compact size, low energy consumption and feasibility for integration with other optoelectronic components are limited, making the semiconductor optical amplifiers (SOA) a realistic solution. An experimental characterization of a broadband and low polarization sensitive asymmetric multi quantum well (MQW) SOA operating in the E-band is reported. The SOA device is composed of nine 6 nm In1-xGaxAsyP1-y 0.2% tensile strained asymmetric MQW layers sandwiched between nine latticed matched 6 nm InGaAsP barrier layers. The active region is grown on an n-doped InP substrate and buried by p-doped InGaAsP layers. The SOA devices have 7-degrees tilt anti-reflected coated facets, with 2 μm ridge width, and a cavity length of 900 μm. For input powers of -10 dBm and -20 dBm, a maximum gain of 20 dB at 1360 nm with a polarization insensitivity under 3 dB for over 90 nm bandwidth is measured. Polarization sensitivity of less than 0.5 dB is observed for some wavelengths. Obtained results indicate a promising SOA with broadband amplification, polarization insensitivity and high gain. These SOAs were designed and characterized at the Photonics Technology Laboratory, University of Ottawa, Canada.

  2. Space-charge limits of ion sensitive probes

    NASA Astrophysics Data System (ADS)

    Brunner, D.; LaBombard, B.; Ochoukov, R.; Sullivan, R.; Whyte, D.

    2013-12-01

    Ion sensitive probes (ISPs) are used to measure ion temperature and plasma potential in magnetized plasmas. Their operation relies on the difference in electron and ion Larmor radii to preferentially collect the ion species on a recessed electrode. Because of their simple two-electrode construction and optimal geometry for heat flux handling they are an attractive probe to use in the high heat flux boundary of magnetic confinement fusion experiments. However, the integrity of its measurements is rarely, if ever, checked under such conditions. Recent measurements with an ISP in the Alcator C-Mod tokamak have shown that its ion current is space-charge limited and thus its current-voltage (I-V) response does not contain information on the ion temperature. We numerically solve a 1D Vlasov-Poisson model of ion collection to determine how much bias is needed to overcome space-charge effects and regain the classic I-V characteristic with an exponential decay. Prompted by the observations of space charge in C-Mod, we have performed a survey of ISP measurements reported in the literature. Evidence of space-charge limited current collection is found on many probes, with few authors noting its presence. Some probes are able to apparently exceed the classic 1D space-charge limit because electrons can E × B drift into the probe volume, partially reducing the net ion charge; it is argued that this does not, however, change the basic problem that space charge compromises the measurement of ion temperature. Guidance is given for design of ISPs to minimize the effects of space charge.

  3. Progress in resolution, sensitivity, and critical dimensional uniformity of EUV chemically amplified resists

    NASA Astrophysics Data System (ADS)

    Thackeray, James; Cameron, James; Jain, Vipul; LaBeaume, Paul; Coley, Suzanne; Ongayi, Owendi; Wagner, Mike; Rachford, Aaron; Biafore, John

    2013-03-01

    This paper will discuss further progress obtained at Dow for the improvement of the Resolution, Contact critical dimension uniformity(CDU), and Sensitivity of EUV chemically amplified resists. For resolution, we have employed the use of polymer-bound photoacid generator (PBP) concept to reduce the intrinsic acid diffusion that limits the ultimate resolving capability of CA resists. For CDU, we have focused on intrinsic dissolution contrast and have found that the photo-decomposable base (PDB) concept can be successfully employed. With the use of a PDB, we can reduce CDU variation at a lower exposure energy. For sensitivity, we have focused on more efficient EUV photon capture through increased EUV absorption, as well as more highly efficient PAGs for greater acid generating efficiency. The formulation concepts will be confirmed using Prolith stochastic resist modeling. For the 26nm hp contact holes, we get excellent overall process window with over 280nm depth of focus for a 10% exposure latitude Process window. The 1sigma Critical dimension uniformity [CDU] is 1.1 nm. We also obtain 20nm hp contact resolution in one of our new EUV resists.

  4. An enhanced primary shock calibration procedure to reduce the zero shift effect of piezoelectric transducers by using a virtual amplifier

    NASA Astrophysics Data System (ADS)

    Nozato, Hideaki; Ota, Akihiro; Kokuyama, Wataru; Volkers, Henrik; Bruns, Thomas

    2016-09-01

    The low-frequency response of a charge amplifier induces an accelerometer (a combination of a piezoelectric transducer and a charge amplifier) output voltage with zero shift. Hence, a virtual amplifier with same input–output characteristics as the charge amplifier was designed to reduce the zero shift effect. The charge shock sensitivities of a piezoelectric transducer were evaluated by applying the input acceleration to the virtual amplifier. The results of the study indicated that the charge shock sensitivities were comparable to the vibration calibration results.

  5. An ultralow noise current amplifier based on superconducting quantum interference device for high sensitivity applications.

    PubMed

    Granata, C; Vettoliere, A; Russo, M

    2011-01-01

    An integrated ultrahigh sensitive current amplifier based on a niobium dc superconducting quantum interference device (SQUID) has been developed. The sensor design is based on a multiturn signal coil coupled to a suitable SQUID magnetometer. The signal coil consists of 60 square niobium turns tightly coupled to a superconducting flux transformer of a SQUID magnetometer. The primary coil (pick-up coil) of the flux transformer has been suitably designed in order to accommodate the multiturn input coil. It has a side length of 10 mm and a width of 2.4 mm. In such a way we have obtained a signal current to magnetic flux transfer coefficient (current sensitivity) as low as 62 nA∕Φ(0). The sensor has been characterized in liquid helium by using a direct coupling low noise readout electronic and a standard modulated electronic in flux locked loop configuration for the noise measurements. Beside the circuit complexity, the sensor has exhibited a smooth and free resonance voltage-flux characteristic guaranteeing a reliable and a stable working operation. Considering a SQUID magnetic flux noise of S(Φ)(1∕2) = 1.8 μΦ(0)∕Hz(1∕2) at T = 4.2 K, a current noise as low as 110 fA∕Hz(1∕2) is obtained. Such a value is about a factor two less than the noise of other SQUIDs of the same category. As an application, Nyquist noise measurements of integrated test resistors using the current sensing noise thermometer technique are reported. Due to its high performance such a sensor can be employed in all applications requiring an extremely current sensitivity like the readout of the gravitational wave detectors and the current sensing noise thermometry. PMID:21280839

  6. Two-color detection with charge sensitive infrared phototransistors

    SciTech Connect

    Kim, Sunmi Kajihara, Yusuke; Komiyama, Susumu; Ueda, Takeji; Satoh, Takashi

    2015-11-02

    Highly sensitive two-color detection is demonstrated at wavelengths of 9 μm and 14.5 μm by using a charge sensitive infrared phototransistor fabricated in a triple GaAs/AlGaAs quantum well (QW) crystal. Two differently thick QWs (7 nm- and 9 nm-thicknesses) serve as photosensitive floating gates for the respective wavelengths via intersubband excitation: The excitation in the QWs is sensed by a third QW, which works as a conducting source-drain channel in the photosensitive transistor. The two spectral bands of detection are shown to be controlled by front-gate biasing, providing a hint for implementing voltage tunable ultra-highly sensitive detectors.

  7. Chemically amplified soft-x-ray resists: sensitivity, resolution, and molecular photodesorption.

    PubMed

    Kubiak, G D; Hwang, R Q; Schulberg, M T; Tichenor, D A; Early, K

    1993-12-01

    The sensitivity, ion photodesorption, and lithographic performance of selected novolac-based chemically amplified resists have been studied at an exposure wavelength of 140 Å. Flood exposures of the resits AZ PF514, AZ PN114, and SAL 601 yield D(0.9) values of 2.5-3.5 mJ/cm(2) for 0.25-µm-thick films. Contrast values range from 3 for AZ PN114 to 5 for SAL 601. Photodesorption of fragment ions induced by 140-Å radiation has been examined in AZ PN114 by using time-of-flight mass spectrometry and compared with poly(methylmethacrylate) (PMMA). Mass-integrated ion desorption yields from AZ PN114 are found to be ∼ 90 times less per exposure than from PMMA. Soft-x-ray projection imaging in AZ PF514 and SAL 601 has been characterized by use of a multilayer-coated 20 × Schwarzschild objective and a transmissive Ge/Si mask illuminated by a laser plasma source. PMID:20856564

  8. LOGARITHMIC AMPLIFIER

    DOEpatents

    De Shong, J.A. Jr.

    1957-12-31

    A logarithmic current amplifier circuit having a high sensitivity and fast response is described. The inventor discovered the time constant of the input circuit of a system utilizing a feedback amplifier, ionization chamber, and a diode, is inversely proportional to the input current, and that the amplifier becomes unstable in amplifying signals in the upper frequency range when the amplifier's forward gain time constant equals the input circuit time constant. The described device incorporates impedance networks having low frequency response characteristic at various points in the circuit to change the forward gain of the amplifler at a rate of 0.7 of the gain magnitude for every two times increased in frequency. As a result of this improvement, the time constant of the input circuit is greatly reduced at high frequencies, and the amplifier response is increased.

  9. Adaptive Epigenetic Differentiation between Upland and Lowland Rice Ecotypes Revealed by Methylation-Sensitive Amplified Polymorphism

    PubMed Central

    Xiong, Jie; Tao, Tao; Zheng, Xiaoguo; Wei, Haibin; Yue, Yunxia; Chen, Liang; Luo, Lijun

    2016-01-01

    The stress-induced epimutations could be inherited over generations and play important roles in plant adaption to stressful environments. Upland rice has been domesticated in water-limited environments for thousands of years and accumulated drought-induced epimutations of DNA methylation, making it epigenetically differentiated from lowland rice. To study the epigenetic differentiation between upland and lowland rice ecotypes on their drought-resistances, the epigenetic variation was investigated in 180 rice landraces under both normal and osmotic conditions via methylation-sensitive amplified polymorphism (MSAP) technique. Great alterations (52.9~54.3% of total individual-locus combinations) of DNA methylation are recorded when rice encountering the osmotic stress. Although the general level of epigenetic differentiation was very low, considerable level of ΦST (0.134~0.187) was detected on the highly divergent epiloci (HDE). The HDE detected in normal condition tended to stay at low levels in upland rice, particularly the ones de-methylated in responses to osmotic stress. Three out of four selected HDE genes differentially expressed between upland and lowland rice under normal or stressed conditions. Moreover, once a gene at HDE was up-/down-regulated in responses to the osmotic stress, its expression under the normal condition was higher/lower in upland rice. This result suggested expressions of genes at the HDE in upland rice might be more adaptive to the osmotic stress. The epigenetic divergence and its influence on the gene expression should contribute to the higher drought-resistance in upland rice as it is domesticated in the water-limited environment. PMID:27380174

  10. Photogeneration of charge carrier correlated with amplified spontaneous emission in single crystals of a thiophene/phenylene co-oligomer.

    PubMed

    Saeki, Akinori; Seki, Shu; Shimizu, Yasuhiro; Yamao, Takeshi; Hotta, Shu

    2010-04-01

    Thiophene/phenylene co-oligomers have substantial promise for the use of not only organic electronics but also organic optical devices. However, considerably less is known about the correlation between their optical and optoelectronic properties. We have investigated the charge carrier generation in 1,4-bis(5-phenylthiophen-2-yl)benzene (AC5) single crystals by flash-photolysis time-resolved microwave conductivity (TRMC) and transient absorption spectroscopy (TAS). It was found that the dependence of photocarrier generation efficiency on excitation photon density differed from that of emission efficiency once amplified spontaneous emission (ASE) and resultant spectrally narrowed emission occur upon exposure to 355 nm. In contrast, the dependences of emission and photocarrier generation efficiencies were identical when ASE was not involved at a different excitation wavelength (193 nm). An approximated analytical solution of rate equation considering ASE or singlet-singlet annihilation was applied to the experiments, exhibiting good agreement. On the basis of TRMC, TAS, and extinction coefficient of radical cation assessed by pulse radiolysis, the minimum charge carrier mobility was estimated, without electrodes, to be 0.12 cm(2) V(-1) s(-1). The dynamics of charge carrier and triplet excited state is discussed, accompanying with examination by time-dependent density functional theory. The present work would open the way to a deeper understanding of the fate of excited state in optically robust organic semiconducting crystals. PMID:20387943

  11. Evaluation of charge-integrating amplifier with silicon MOSFETs for cryogenic readout

    NASA Astrophysics Data System (ADS)

    Noda, Manabu; Shibai, Hiroshi; Watabe, Toyoki; Hirao, Takanori; Yoda, Hiroyuki; Nagata, Hirohisa; Nakagawa, Takao; Kawada, Mitsunobu

    1998-08-01

    Low-noise and low-power cryogenic readout electronics are developed for a focal plane instrument of the IR Imaging Surveyor. We measured the static characteristics and the noise spectra of several types of silicon MOSFETs at the cryogenic temperature where silicon JFETs do not work well due to the carrier freeze-out. The 'kink' behavior of n- channel MOSFETs was observed below the carrier freeze-out temperature, but it was not obvious for the p-channel MOSFET. It was demonstrated the p-channel MOSFETs can be used for the cryogenic readout electronics of the IRIS's far-IR array with an acceptable performance. The amplifier integrated with these MOSFETs showed low-noise at 2K under a low power consumption of 1 (mu) W per MOSFET. We now design and evaluate several circuits that are fabricated by the CMOS process for cryogenic readout.

  12. Design of Low-Noise Output Amplifiers for P-channel Charge-Coupled Devices Fabricated on High-Resistivity Silicon

    SciTech Connect

    Haque, S; Frost, F Dion R.; Groulx, R; Holland, S E; Karcher, A; Kolbe, W F; Roe, N A; Wang, G; Yu, Y

    2011-12-22

    We describe the design and optimization of low-noise, single-stage output amplifiers for p-channel charge-coupled devices (CCDs) used for scientific applications in astronomy and other fields. The CCDs are fabricated on high-resistivity, 4000–5000 -cm, n-type silicon substrates. Single-stage amplifiers with different output structure designs and technologies have been characterized. The standard output amplifier is designed with an n{sup +} polysilicon gate that has a metal connection to the sense node. In an effort to lower the output amplifier readout noise by minimizing the capacitance seen at the sense node, buried-contact technology has been investigated. In this case, the output transistor has a p{sup +} polysilicon gate that connects directly to the p{sup +} sense node. Output structures with buried-contact areas as small as 2 μm × 2 μm are characterized. In addition, the geometry of the source-follower transistor was varied, and we report test results on the conversion gain and noise of the various amplifier structures. By use of buried-contact technology, better amplifier geometry, optimization of the amplifier biases and improvements in the test electronics design, we obtain a 45% reduction in noise, corresponding to 1.7 e{sup -} rms at 70 kpixels/sec.

  13. A Stimulated Raman Scattering CMOS Pixel Using a High-Speed Charge Modulator and Lock-in Amplifier.

    PubMed

    Lioe, De Xing; Mars, Kamel; Kawahito, Shoji; Yasutomi, Keita; Kagawa, Keiichiro; Yamada, Takahiro; Hashimoto, Mamoru

    2016-01-01

    A complementary metal-oxide semiconductor (CMOS) lock-in pixel to observe stimulated Raman scattering (SRS) using a high speed lateral electric field modulator (LEFM) for photo-generated charges and in-pixel readout circuits is presented. An effective SRS signal generated after the SRS process is very small and needs to be extracted from an extremely large offset due to a probing laser signal. In order to suppress the offset components while amplifying high-frequency modulated small SRS signal components, the lock-in pixel uses a high-speed LEFM for demodulating the SRS signal, resistor-capacitor low-pass filter (RC-LPF) and switched-capacitor (SC) integrator with a fully CMOS differential amplifier. AC (modulated) components remained in the RC-LPF outputs are eliminated by the phase-adjusted sampling with the SC integrator and the demodulated DC (unmodulated) components due to the SRS signal are integrated over many samples in the SC integrator. In order to suppress further the residual offset and the low frequency noise (1/f noise) components, a double modulation technique is introduced in the SRS signal measurements, where the phase of high-frequency modulated laser beam before irradiation of a specimen is modulated at an intermediate frequency and the demodulation is done at the lock-in pixel output. A prototype chip for characterizing the SRS lock-in pixel is implemented and a successful operation is demonstrated. The reduction effects of residual offset and 1/f noise components are confirmed by the measurements. A ratio of the detected small SRS to offset a signal of less than 10(-)⁵ is experimentally demonstrated, and the SRS spectrum of a Benzonitrile sample is successfully observed. PMID:27089339

  14. A Stimulated Raman Scattering CMOS Pixel Using a High-Speed Charge Modulator and Lock-in Amplifier

    PubMed Central

    Lioe, De Xing; Mars, Kamel; Kawahito, Shoji; Yasutomi, Keita; Kagawa, Keiichiro; Yamada, Takahiro; Hashimoto, Mamoru

    2016-01-01

    A complementary metal-oxide semiconductor (CMOS) lock-in pixel to observe stimulated Raman scattering (SRS) using a high speed lateral electric field modulator (LEFM) for photo-generated charges and in-pixel readout circuits is presented. An effective SRS signal generated after the SRS process is very small and needs to be extracted from an extremely large offset due to a probing laser signal. In order to suppress the offset components while amplifying high-frequency modulated small SRS signal components, the lock-in pixel uses a high-speed LEFM for demodulating the SRS signal, resistor-capacitor low-pass filter (RC-LPF) and switched-capacitor (SC) integrator with a fully CMOS differential amplifier. AC (modulated) components remained in the RC-LPF outputs are eliminated by the phase-adjusted sampling with the SC integrator and the demodulated DC (unmodulated) components due to the SRS signal are integrated over many samples in the SC integrator. In order to suppress further the residual offset and the low frequency noise (1/f noise) components, a double modulation technique is introduced in the SRS signal measurements, where the phase of high-frequency modulated laser beam before irradiation of a specimen is modulated at an intermediate frequency and the demodulation is done at the lock-in pixel output. A prototype chip for characterizing the SRS lock-in pixel is implemented and a successful operation is demonstrated. The reduction effects of residual offset and 1/f noise components are confirmed by the measurements. A ratio of the detected small SRS to offset a signal of less than 10−5 is experimentally demonstrated, and the SRS spectrum of a Benzonitrile sample is successfully observed. PMID:27089339

  15. Classicalization times of parametrically amplified “Schrödinger cat” states coupled to phase-sensitive reservoirs

    NASA Astrophysics Data System (ADS)

    Dodonov, V. V.; Valverde, C.; Souza, L. S.; Baseia, B.

    2011-10-01

    The exact Wigner function of a parametrically excited quantum oscillator in a phase-sensitive amplifying/attenuating reservoir is found for initial even/odd coherent states. Studying the evolution of negativity of the Wigner function we show the difference between the “initial positivization time” (IPT), which is inversely proportional to the square of the initial size of the superposition, and the “final positivization time” (FPT), which does not depend on this size. Both these times can be made arbitrarily long in maximally squeezed high-temperature reservoirs. Besides, we find the conditions when some (small) squeezing can exist even after the Wigner function becomes totally positive.

  16. Inhibition of cathepsin proteases attenuates migration and sensitizes aggressive N-Myc amplified human neuroblastoma cells to doxorubicin

    PubMed Central

    Gangoda, Lahiru; Keerthikumar, Shivakumar; Fonseka, Pamali; Edgington, Laura E.; Ang, Ching-Seng; Ozcitti, Cemil; Bogyo, Matthew; Parker, Belinda S.; Mathivanan, Suresh

    2015-01-01

    Neuroblastoma arises from the sympathetic nervous system and accounts for 15% of childhood cancer mortality. Amplification of the oncogene N-Myc is reported to occur in more than 20% of patients. While N-Myc amplification status strongly correlates with higher tumour aggression and resistance to treatment, the role of N-Myc in the aggressive progression of the disease is poorly understood. N-Myc being a transcription factor can modulate the secretion of key proteins that may play a pivotal role in tumorigenesis. Characterising the soluble secreted proteins or secretome will aid in understanding their role in the tumour microenvironment, such as promoting cancer cell invasion and resistance to treatment. The aim of this study is to characterise the secretome of human malignant neuroblastoma SK-N-BE2 (N-Myc amplified, more aggressive) and SH-SY5Y (N-Myc non-amplified, less aggressive) cells. Conditioned media from SK-N-BE2 and SH-SY5Y cell lines were subjected to proteomics analysis. We report a catalogue of 894 proteins identified in the secretome isolated from the two neuroblastoma cell lines, SK-N-BE2 and SH-SY5Y. Functional enrichment analysis using FunRich software identified enhanced secretion of proteins implicated in cysteine peptidase activity in the aggressive N-Myc amplified SK-N-BE2 secretome compared to the less tumorigenic SH-SY5Y cells. Protein-protein interaction-based network analysis highlighted the enrichment of cathepsin and epithelial-to-mesenchymal transition sub-networks. For the first time, inhibition of cathepsins by inhibitors sensitized the resistant SK-N-BE2 cells to doxorubicin as well as decreased its migratory potential. The dataset of secretome proteins of N-Myc amplified (more aggressive) and non-amplified (less aggressive) neuroblastoma cells represent the first inventory of neuroblastoma secretome. The study also highlights the prominent role of cathepsins in the N-Myc amplified neuroblastoma pathogenesis. As N-Myc amplification

  17. Analysis of DNA methylation of maize in response to osmotic and salt stress based on methylation-sensitive amplified polymorphism.

    PubMed

    Tan, Ming-pu

    2010-01-01

    Water stress is known to alter cytosine methylation, which generally represses transcription. However, little is known about the role of methylation alteration in maize under osmotic stress. Here, methylation-sensitive amplified polymorphism (MSAP) was used to screen PEG- or NaCl-induced methylation alteration in maize seedlings. The sequences of 25 differentially amplified fragments relevant to stress were successfully obtained. Two stress-specific fragments from leaves, LP166 and LPS911, shown to be homologous to retrotransposon Gag-Pol protein genes, suggested that osmotic stress-induced methylation of retrotransposons. Three MSAP fragments, representing drought-induced or salt-induced methylation in leaves, were homologous to a maize aluminum-induced transporter. Besides these, heat shock protein HSP82, Poly [ADP-ribose] polymerase 2, Lipoxygenase, casein kinase (CK2), and dehydration-responsive element-binding (DREB) factor were also homologs of MSAP sequences from salt-treated roots. One MSAP fragment amplified from salt-treated roots, designated RS39, was homologous to the first intron of maize protein phosphatase 2C (zmPP2C), whereas - LS103, absent from salt-treated leaves, was homologous to maize glutathione S-transferases (zmGST). Expression analysis showed that salt-induced intron methylation of root zmPP2C significantly downregulated its expression, while salt-induced demethylation of leaf zmGST weakly upregulated its expression. The results suggested that salinity-induced methylation downregulated zmPP2C expression, a negative regulator of the stress response, while salinity-induced demethylation upregulated zmGST expression, a positive effecter of the stress response. Altered methylation, in response to stress, might also be involved in stress acclimation. PMID:19889550

  18. A self-amplified transistor immunosensor under dual gate operation: highly sensitive detection of hepatitis B surface antigen

    NASA Astrophysics Data System (ADS)

    Lee, I.-K.; Jeun, M.; Jang, H.-J.; Cho, W.-J.; Lee, K. H.

    2015-10-01

    Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor based on a self-amplified transistor under dual gate operation (immuno-DG ISFET) for the detection of hepatitis B surface antigen. To address the challenges in current ISFET-based immunosensors, we have enhanced the sensitivity of an immunosensor by precisely tailoring the nanostructure of the transistor. In the pH sensing test, the immuno-DG ISFET showed superior sensitivity (2085.53 mV per pH) to both standard ISFET under single gate operation (58.88 mV per pH) and DG ISFET with a non-tailored transistor (381.14 mV per pH). Moreover, concerning the detection of hepatitis B surface antigens (HBsAg) using the immuno-DG ISFET, we have successfully detected trace amounts of HBsAg (22.5 fg mL-1) in a non-diluted 1× PBS medium with a high sensitivity of 690 mV. Our results demonstrate that the proposed immuno-DG ISFET can be a biosensor platform for practical use in the diagnosis of various diseases.Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor

  19. Sand and sandbar willow: a feedback loop amplifies environmental sensitivity at the riparian interface.

    PubMed

    Rood, Stewart B; Goater, Lori A; Gill, Karen M; Braatne, Jeffrey H

    2011-01-01

    Riparian or streamside zones support dynamic ecosystems with three interacting components: flowing water, alluvia (river-transported sediments), and vegetation. River damming influences all three, and subsequent responses can provide insight into underlying processes. We investigated these components along the 315-km Hells Canyon corridor of the Snake River that included reaches upstream, along, and downstream from three large dams and reservoirs, and along the Salmon River, a free-flowing tributary. Sandbar willow was generally the woody plant at the lowest bank position and was abundant along upstream reaches (53, 45, 67% of transects), sparse along reservoirs (11, 12, 0%), and sparse along the Snake River downstream (11%). It was prolific along the undammed Salmon River (83%) and intermediate along the Snake River below the Salmon inflow (27%), indicating partial recovery with the contribution of water and sediments. Along these rivers, it commonly occurred on sandy substrates, especially on shallow-sloped surfaces, and emerged from interstitial sands between cobbles on steeper surfaces. However, along the Snake River below the dams, sandbars have eroded and willows were sparse on remnant, degrading sand surfaces. We conclude that a feedback loop exists between sands and sandbar willow. Sand favors willow colonization and clonal expansion, and reciprocally the extensively branched willows create slack-water zones that protect and trap sands. This feedback may sustain surface sands and sandbar willows along free-flowing river systems and it amplifies their mutual vulnerability to river damming. Following damming, sediment-depleted water is released downstream, eroding surface sands and reducing willow colonization and expansion. With willow decline, sands are further exposed and eroded, compounding these impacts. From this feedback, we predict the coordinated depletion of surface sands and riparian willows along dammed rivers throughout the Northern Hemisphere

  20. TRPA1 mediates amplified sympathetic responsiveness to activation of metabolically sensitive muscle afferents in rats with femoral artery occlusion

    PubMed Central

    Xing, Jihong; Lu, Jian; Li, Jianhua

    2015-01-01

    Autonomic responses to activation of mechanically and metabolically sensitive muscle afferent nerves during static contraction are augmented in rats with femoral artery occlusion. Moreover, metabolically sensitive transient receptor potential cation channel subfamily A, member 1 (TRPA1) has been reported to contribute to sympathetic nerve activity (SNA) and arterial blood pressure (BP) responses evoked by static muscle contraction. Thus, in the present study, we examined the mechanisms by which afferent nerves' TRPA1 plays a role in regulating amplified sympathetic responsiveness due to a restriction of blood flow directed to the hindlimb muscles. Our data show that 24–72 h of femoral artery occlusion (1) upregulates the protein levels of TRPA1 in dorsal root ganglion (DRG) tissues; (2) selectively increases expression of TRPA1 in DRG neurons supplying metabolically sensitive afferent nerves of C-fiber (group IV); and (3) enhances renal SNA and BP responses to AITC (a TRPA1 agonist) injected into the hindlimb muscles. In addition, our data demonstrate that blocking TRPA1 attenuates SNA and BP responses during muscle contraction to a greater degree in ligated rats than those responses in control rats. In contrast, blocking TRPA1 fails to attenuate SNA and BP responses during passive tendon stretch in both groups. Overall, results of this study indicate that alternations in muscle afferent nerves' TRPA1 likely contribute to enhanced sympathetically mediated autonomic responses via the metabolic component of the muscle reflex under circumstances of chronic muscle ischemia. PMID:26441669

  1. Amplifying the sensitivity of zinc(II) responsive MRI contrast agents by altering water exchange rates.

    PubMed

    Yu, Jing; Martins, André F; Preihs, Christian; Clavijo Jordan, Veronica; Chirayil, Sara; Zhao, Piyu; Wu, Yunkou; Nasr, Khaled; Kiefer, Garry E; Sherry, A Dean

    2015-11-11

    Given the known water exchange rate limitations of a previously reported Zn(II)-sensitive MRI contrast agent, GdDOTA-diBPEN, new structural targets were rationally designed to increase the rate of water exchange to improve MRI detection sensitivity. These new sensors exhibit fine-tuned water exchange properties and, depending on the individual structure, demonstrate significantly improved longitudinal relaxivities (r1). Two sensors in particular demonstrate optimized parameters and, therefore, show exceptionally high longitudinal relaxivities of about 50 mM(-1) s(-1) upon binding to Zn(II) and human serum albumin (HSA). This value demonstrates a 3-fold increase in r1 compared to that displayed by the original sensor, GdDOTA-diBPEN. In addition, this study provides important insights into the interplay between structural modifications, water exchange rate, and kinetic stability properties of the sensors. The new high relaxivity agents were used to successfully image Zn(II) release from the mouse pancreas in vivo during glucose stimulated insulin secretion. PMID:26462412

  2. A label-free and cascaded dual-signaling amplified electrochemical aptasensing platform for sensitive prion assay.

    PubMed

    Yu, Peng; Zhang, Xiaohua; Xiong, Erhu; Zhou, Jiawan; Li, Xiaoyu; Chen, Jinhua

    2016-11-15

    Prion proteins, as an important biomarker of prion disease, are responsible for the transmissible spongiform encephalopathies (a group of fatal neurodegenerative diseases). Hence, the sensitive detection of prion protein is very essential for biological studies and medical diagnostics. In this paper, a novel label-free and cascaded dual-signaling amplified electrochemical strategy was developed for sensitive and selective analysis of cellular prion protein (PrP(C)). The recognition elements included double-stranded DNA consisted of PrP(C)-binding aptamer (DNA1) and its partially complementary DNA (DNA2), and ordered mesoporous carbon probe (OMCP) fabricated by sealing the electroactive ferrocenecarboxylic acid (Fc) into its inner pores and then using single-stranded DNA (DNA3) as the gatekeeper. In the presence of PrP(C), DNA1 could bind the target protein and free DNA2. More importantly, DNA2 could hybridize with DNA3 to form a rigid duplex DNA and thus triggered the exonuclease III (Exo III) cleavage process to realize the DNA2 recycling, accompanied by opening more biogates and releasing more Fc. The released Fc could be further used as a competitive guest of β-cyclodextrin (β-CD) to displace the Rhodamine B (RhB) on the electrode. As a result, an amplified oxidation peak current of Fc (RhB) increased (decreased) with the increase of PrP(C) concentration. When "ΔI=ΔIFc+|ΔIRhB|" (ΔIFc and ΔIRhB were the change values of the oxidation peak currents of Fc and RhB, respectively.) was used as the response signal for quantitative determination of PrP(C), the detection limit was 7.6fM (3σ), which was much lower than that of the most reported methods for PrP(C) assay. This strategy provided a simple and sensitive approach for the detection of PrP(C) and has a great potential for bioanalysis, disease diagnostics, and clinical biomedicine applications. PMID:27208480

  3. Amplified photoacoustic performance and enhanced photothermal stability of reduced graphene oxide coated gold nanorods for sensitive photoacoustic imaging.

    PubMed

    Moon, Hyungwon; Kumar, Dinesh; Kim, Haemin; Sim, Changbeom; Chang, Jin-Ho; Kim, Jung-Mu; Kim, Hyuncheol; Lim, Dong-Kwon

    2015-03-24

    We report a strongly amplified photoacoustic (PA) performance of the new functional hybrid material composed of reduced graphene oxide and gold nanorods. Due to the excellent NIR light absorption properties of the reduced graphene oxide coated gold nanorods (r-GO-AuNRs) and highly efficient heat transfer process through the reduced graphene oxide layer, r-GO-AuNRs exhibit excellent photothermal stability and significantly higher photoacoustic amplitudes than those of bare-AuNRs, nonreduced graphene oxide coated AuNRs (GO-AuNRs), or silica-coated AuNR, as demonstrated in both in vitro and in vivo systems. The linear response of PA amplitude from reduced state controlled GO on AuNR indicates the critical role of GO for a strong photothermal effect of r-GO-AuNRs. Theoretical studies with finite-element-method lab-based simulation reveal that a 4 times higher magnitude of the enhanced electromagnetic field around r-GO-AuNRs can be generated compared with bare AuNRs or GO-AuNRs. Furthermore, the r-GO-AuNRs are expected to be a promising deep-tissue imaging probe because of extraordinarily high PA amplitudes in the 4-11 MHz operating frequency of an ultrasound transducer. Therefore, the r-GO-AuNRs can be a useful imaging probe for highly sensitive photoacoustic images and NIR sensitive therapeutics based on a strong photothermal effect. PMID:25751167

  4. Free fatty acids sensitize dendritic cells to amplify TH1/TH17-immune responses.

    PubMed

    Stelzner, Kristin; Herbert, Diana; Popkova, Yulia; Lorz, Axel; Schiller, Jürgen; Gericke, Martin; Klöting, Nora; Blüher, Matthias; Franz, Sandra; Simon, Jan C; Saalbach, Anja

    2016-08-01

    Obesity is associated with body fat gain and impaired glucose metabolism. Here, we identified both body fat gain in obesity and impaired glucose metabolism as two independent risk factors for increased serum levels of free fatty acids (FFAs). Since obesity is associated with increased and/or delayed resolution of inflammation observed in various chronic inflammatory diseases such as psoriasis, we investigated the impact of FFAs on human monocyte-derived and mouse bone marrow-derived dendritic cell (DCs) functions relevant for the pathogenesis of chronic inflammation. FFAs such as palmitic acid (PA) and oleic acid (OA) did not affect the pro-inflammatory immune response of DCs. In contrast, PA and OA sensitize DCs resulting in augmented secretion of TH1/TH17-instructive cytokines upon pro-inflammatory stimulation. Interestingly, obesity in mice worsened a TH1/TH17-driven psoriasis-like skin inflammation. Strong correlation of the amount of total FFA, PA, and OA in serum with the severity of skin inflammation points to a critical role of FFA in obesity-mediated exacerbation of skin inflammation. Our data suggest that increased levels of FFAs might be a predisposing factor promoting a TH1/TH17-mediated inflammation such as psoriasis in response to an inflammatory danger signal. PMID:27214608

  5. Temperature sensitivity analysis of dopingless charge-plasma transistor

    NASA Astrophysics Data System (ADS)

    Shrivastava, Vishwas; Kumar, Anup; Sahu, Chitrakant; Singh, Jawar

    2016-03-01

    The junctionless field-effect transistors (JLFETs) have shown potential to scale down in sub-10 nm regime due to simplified fabrication process and less short-channel effects (SCEs), however, sensitivity towards process parameter variation is a major concern. Therefore, in this paper, sensitivity towards temperature variation of recently proposed dopingless (DL) double-gate field-effect transistor (DGFET) and JL-DGFET is reported. Different digital and analog performance metrics were considered and compared for both devices of similar geometries. We observed that the drive current of DL-DGFET decreases with temperature, while, it increases in JL-DGFET because both devices are affected by different scattering mechanisms at higher temperature. The variation in ION and IOFF in DL-DGFET are only 0.095 μ A/K and 0.2 nA /K , respectively, while, in JL-DGFET the changes are 0.25 μ A/K and 0.34 nA /K , respectively, above room temperature. Below room temperature, it was found that the incomplete ionization effect in JL-DGFET severely affects the drive current, however, DL-DGFET remains unaffected. Hence, the proposed DL-DGFET is less sensitive towards temperature variation and can be employed for cryogenics to high temperature applications.

  6. Space charge instabilities in gyrotron beams and theory of gyro-traveling-wave-amplifiers at cyclotron harmonics

    SciTech Connect

    Li, H.

    1993-01-01

    This dissertation concerns itself with two important issues in the study of gyrotrons. In Part I, the authors study the space charge instabilities in gyrotron electron beams via both solution of the linear dispersion equation and the nonlinear particle simulation. The linear analysis addressed the stabilizing effects of energy spread in the beams and the gradient of the external magnetic field. The nonlinear multi-frequency simulation demonstrates that the energy spread induced by multiple unstable waves in the nonlinear saturation stage is more significant than the corresponding spread induced by a single unstable wave. This indicates that the deleterious effect on the quality of the beam will be greater than previously expected, and emphasizes the need to design electron guns which are stable to this wave mode. In Part II, the authors develop a generalized theory of gyro-traveling-wave tubes (gyro-TWTs) operating at arbitrary cyclotron harmonics. In the framework of small signal theory, the authors obtain and analyze the dispersion equation and discuss a problem of spurious counterpropagating waves excitation. In the large-signal study, the authors predict the possibility of achieving high efficiency of operation at the first four cyclotron harmonics and show that the orbital efficiency of the relativistic gyro-TWT operating at the second cyclotron harmonic with large frequency up-conversion may exceed 60%. The results obtained also demonstrate that the sensitivity of the harmonic gyro-TWT efficiency with respect to the electron velocity spread strongly depends on axial wavenumbers of the travelling waves.

  7. Reduced Sensitivity to Charge Noise in Semiconductor Spin Qubits via Symmetric Operation

    NASA Astrophysics Data System (ADS)

    Reed, M. D.; Maune, B. M.; Andrews, R. W.; Borselli, M. G.; Eng, K.; Jura, M. P.; Kiselev, A. A.; Ladd, T. D.; Merkel, S. T.; Milosavljevic, I.; Pritchett, E. J.; Rakher, M. T.; Ross, R. S.; Schmitz, A. E.; Smith, A.; Wright, J. A.; Gyure, M. F.; Hunter, A. T.

    2016-03-01

    We demonstrate improved operation of exchange-coupled semiconductor quantum dots by substantially reducing the sensitivity of exchange operations to charge noise. The method involves biasing a double dot symmetrically between the charge-state anticrossings, where the derivative of the exchange energy with respect to gate voltages is minimized. Exchange remains highly tunable by adjusting the tunnel coupling. We find that this method reduces the dephasing effect of charge noise by more than a factor of 5 in comparison to operation near a charge-state anticrossing, increasing the number of observable exchange oscillations in our qubit by a similar factor. Performance also improves with exchange rate, favoring fast quantum operations.

  8. Frequency range selection method of trans-impedance amplifier for high sensitivity lock-in amplifier used in the optical sensors

    NASA Astrophysics Data System (ADS)

    Park, Chang-In; Jeon, Su-Jin; Hong, Nam-Pyo; Choi, Young-Wan

    2016-03-01

    Lock-in amplifier (LIA) has been proposed as a detection technique for optical sensors because it can measure low signal in high noise level. LIA uses synchronous method, so the input signal frequency is locked to a reference frequency that is used to carry out the measurements. Generally, input signal frequency of LIA used in optical sensors is determined by modulation frequency of optical signal. It is important to understand the noise characteristics of the trans-impedance amplifier (TIA) to determine the modulation frequency. The TIA has a frequency range in which noise is minimized by the capacitance of photo diode (PD) and the passive component of TIA feedback network. When the modulation frequency is determined in this range, it is possible to design a robust system to noise. In this paper, we propose a method for the determination of optical signal modulation frequency selection by using the noise characteristics of TIA. Frequency response of noise in TIA is measured by spectrum analyzer and minimum noise region is confirmed. The LIA and TIA circuit have been designed as a hybrid circuit. The optical sensor is modeled by the laser diode (LD) and photo diode (PD) and the modulation frequency was used as the input to the signal generator. The experiments were performed to compare the signal to noise ratio (SNR) of the minimum noise region and the others. The results clearly show that the SNR is enhanced in the minimum noise region of TIA.

  9. Sensitive and specific detection of Xanthomonas campestris pv. pelargonii with DNA primers and probes identified by random amplified polymorphic DNA analysis.

    PubMed Central

    Manulis, S; Valinsky, L; Lichter, A; Gabriel, D W

    1994-01-01

    The random amplified polymorphic DNA method was used to distinguish strains of Xanthomonas campestris pv. pelargonii from 21 other Xanthomonas species and/or pathovars. Among the 42 arbitrarily chosen primers evaluated, 3 were found to reveal diagnostic polymorphisms when purified DNAs from compared strains were amplified by the PCR. The three primers revealed DNA amplification patterns which were conserved among all 53 strains tested of X. campestris pv. pelargonii isolated from various locations worldwide. The distinctive X. compestris pv. pelargonii patterns were clearly different from those obtained with any of 46 other Xanthomonas strains tested. An amplified 1.2-kb DNA fragment, apparently unique to X. campestris pv. pelargonii by these random amplified polymorphic DNA tests, was cloned and evaluated as a diagnostic DNA probe. It hybridized with total DNA from all 53 X. campestris pv. pelargonii strains tested and not with any of the 46 other Xanthomonas strains tested. The DNA sequence of the terminal ends of this 1.2-kb fragment was obtained and used to design a pair of 18-mer oligonucleotide primers specific for X. campestris pv. pelargonii. The custom-synthesized primers amplified the same 1.2-kb DNA fragment from all 53 X. campestris pv. pelargonii strains tested and failed to amplify DNA from any of the 46 other Xanthomonas strains tested. DNA isolated from saprophytes associated with the geranium plant also did not produce amplified DNA with these primers. The sensitivity of the PCR assay using the custom-synthesized primers was between 10 and 50 cells.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:7993095

  10. Method and apparatus for detection of charge on ions and particles

    DOEpatents

    Fuerstenau, Stephen Douglas; Soli, George Arthur

    2002-01-01

    The present invention provides a tessellated array detector with charge collecting plate (or cup) electrode pixels and amplifying circuitry integrated into each pixel making it sensitive to external electrostatic charge; a micro collector/amplifier pixel design possessing a small capacitance to ensure a high charge to voltage signal conversion for low noise/high sensitivity operation; a micro-fabricated array of such pixels to create a useful macroscopic target area for ion and charged particle collection.

  11. A sensitive charge scanning probe based on silicon single electron transistor

    NASA Astrophysics Data System (ADS)

    Lina, Su; Xinxing, Li; Hua, Qin; Xiaofeng, Gu

    2016-04-01

    Single electron transistors (SETs) are known to be extremely sensitive electrometers owing to their high charge sensitivity. In this work, we report the design, fabrication, and characterization of a silicon-on-insulator-based SET scanning probe. The fabricated SET is located about 10 μm away from the probe tip. The SET with a quantum dot of about 70 nm in diameter exhibits an obvious Coulomb blockade effect measured at 4.1 K. The Coulomb blockade energy is about 18 meV, and the charge sensitivity is in the order of 10‑5‑10‑3 e/Hz1/2. This SET scanning probe can be used to map charge distribution and sense dynamic charge fluctuation in nanodevices or circuits under test, realizing high sensitivity and high spatial resolution charge detection. Project supported by the Instrument Developing Project of the Chinese Academy of Sciences (No. YZ201152), the National Natural Science Foundation of China (No. 11403084), the Fundamental Research Funds for Central Universities (Nos. JUSRP51510, JUDCF12032), and the Graduate Student Innovation Program for Universities of Jiangsu Province (No. CXLX12_0724).

  12. New light-amplifier-based detector designs for high spatial resolution and high sensitivity CBCT mammography and fluoroscopy

    PubMed Central

    Rudin, Stephen; Kuhls, Andrew T.; Yadava, Girijesh K.; Josan, Gaurav C.; Wu, Ye; Chityala, Ravishankar N.; Rangwala, Hussain S.; Ciprian Ionita, N.; Hoffmann, Kenneth R.; Bednarek, Daniel R.

    2011-01-01

    New cone-beam computed tomographic (CBCT) mammography system designs are presented where the detectors provide high spatial resolution, high sensitivity, low noise, wide dynamic range, negligible lag and high frame rates similar to features required for high performance fluoroscopy detectors. The x-ray detectors consist of a phosphor coupled by a fiber-optic taper to either a high gain image light amplifier (LA) then CCD camera or to an electron multiplying CCD. When a square-array of such detectors is used, a field-of-view (FOV) to 20 × 20 cm can be obtained where the images have pixel-resolution of 100 µm or better. To achieve practical CBCT mammography scan-times, 30 fps may be acquired with quantum limited (noise free) performance below 0.2 µR detector exposure per frame. Because of the flexible voltage controlled gain of the LA’s and EMCCDs, large detector dynamic range is also achievable. Features of such detector systems with arrays of either generation 2 (Gen 2) or 3 (Gen 3) LAs optically coupled to CCD cameras or arrays of EMCCDs coupled directly are compared. Quantum accounting analysis is done for a variety of such designs where either the lowest number of information carriers off the LA photo-cathode or electrons released in the EMCCDs per x-ray absorbed in the phosphor are large enough to imply no quantum sink for the design. These new LA- or EMCCD-based systems could lead to vastly improved CBCT mammography, ROI-CT, or fluoroscopy performance compared to systems using flat panels. PMID:21297904

  13. SEU critical charge and sensitive area in a submicron CMOS technology

    SciTech Connect

    Detcheverry, C.; Dachs, C.; Lorfevre, E.; Sudre, C.; Bruguier, G.; Palau, J.M.; Gasiot, J.; Ecoffet, R.

    1997-12-01

    This work presents SEU phenomena in advanced SRAM memory cells. Using mixed-mode simulation, the effects of scaling on the notions of sensitive area and critical charge is shown. Specifically, the authors quantify the influence of parasitic bipolar action in cells fabricated in a submicron technology.

  14. Enhanced Laboratory Sensitivity to Variation of the Fine-Structure Constant using Highly Charged Ions

    SciTech Connect

    Berengut, J. C.; Dzuba, V. A.; Flambaum, V. V.

    2010-09-17

    We study atomic systems that are in the frequency range of optical atomic clocks and have enhanced sensitivity to potential time variation of the fine-structure constant {alpha}. The high sensitivity is due to coherent contributions from three factors: high nuclear charge Z, high ionization degree, and significant differences in the configuration composition of the states involved. Configuration crossing keeps the frequencies in the optical range despite the large ionization energies. We discuss a few promising examples that have the largest {alpha} sensitivities seen in atomic systems.

  15. Gated charged-particle trap

    DOEpatents

    Benner, W. Henry

    1999-01-01

    The design and operation of a new type of charged-particle trap provides simultaneous measurements of mass, charge, and velocity of large electrospray ions. The trap consists of a detector tube mounted between two sets of center-bored trapping plates. Voltages applied to the trapping plates define symmetrically-opposing potential valleys which guide axially-injected ions to cycle back and forth through the charge-detection tube. A low noise charge-sensitive amplifier, connected to the tube, reproduces the image charge of individual ions as they pass through the detector tube. Ion mass is calculated from measurement of ion charge and velocity following each passage through the detector.

  16. Real-space observation of unbalanced charge distribution inside a perovskite-sensitized solar cell.

    PubMed

    Bergmann, Victor W; Weber, Stefan A L; Javier Ramos, F; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Li, Dan; Domanski, Anna L; Lieberwirth, Ingo; Ahmad, Shahzada; Berger, Rüdiger

    2014-01-01

    Perovskite-sensitized solar cells have reached power conversion efficiencies comparable to commercially available solar cells used for example in solar farms. In contrast to silicon solar cells, perovskite-sensitized solar cells can be made by solution processes from inexpensive materials. The power conversion efficiency of these cells depends substantially on the charge transfer at interfaces. Here we use Kelvin probe force microscopy to study the real-space cross-sectional distribution of the internal potential within high efficiency mesoscopic methylammonium lead tri-iodide solar cells. We show that the electric field is homogeneous through these devices, similar to that of a p-i-n type junction. On illumination under short-circuit conditions, holes accumulate in front of the hole-transport layer as a consequence of unbalanced charge transport in the device. After light illumination, we find that trapped charges remain inside the active device layers. Removing these traps and the unbalanced charge injection could enable further improvements in performance of perovskite-sensitized solar cells. PMID:25242041

  17. Low noise charge sensitive preamplifier DC stabilized without a physical resistor

    DOEpatents

    Bertuccio, G.; Rehak, P.; Xi, D.

    1994-09-13

    The invention is a novel charge sensitive preamplifier (CSP) which has no resistor in parallel with the feedback capacitor. No resetting circuit is required to discharge the feedback capacitor. The DC stabilization of the preamplifier is obtained by means of a second feedback loop between the preamplifier output and the common base transistor of the input cascode. The input transistor of the preamplifier is a Junction Field Transistor (JFET) with the gate-source junction forward biased. The detector leakage current flows into this junction. This invention is concerned with a new circuit configuration for a charge sensitive preamplifier and a novel use of the input Field Effect Transistor of the CSP itself. In particular this invention, in addition to eliminating the feedback resistor, eliminates the need for external devices between the detector and the preamplifier, and it eliminates the need for external circuitry to sense the output voltage and reset the CSP. Furthermore, the noise level of the novel CSP is very low, comparable with the performance achieved with other solutions. Experimental tests prove that this configuration for the charge sensitive preamplifier permits an excellent noise performance at temperatures including room temperature. An equivalent noise charge of less than 20 electrons r.m.s. has been measured at room temperature by using a commercial JFET as input device of the preamplifier. 6 figs.

  18. Low noise charge sensitive preamplifier DC stabilized without a physical resistor

    DOEpatents

    Bertuccio, Giuseppe; Rehak, Pavel; Xi, Deming

    1994-09-13

    The invention is a novel charge sensitive preamplifier (CSP) which has no resistor in parallel with the feedback capacitor. No resetting circuit is required to discharge the feedback capacitor. The DC stabilization of the preamplifier is obtained by means of a second feedback loop between the preamplifier output and the common base transistor of the input cascode. The input transistor of the preamplifier is a Junction Field Transistor (JFET) with the gate-source junction forward biased. The detector leakage current flows into this junction. This invention is concerned with a new circuit configuration for a charge sensitive preamplifier and a novel use of the input Field Effect Transistor of the CSP itself. In particular this invention, in addition to eliminating the feedback resistor, eliminates the need for external devices between the detector and the preamplifier, and it eliminates the need for external circuitry to sense the output voltage and reset the CSP. Furthermore, the noise level of the novel CSP is very low, comparable with the performance achieved with other solutions. Experimental tests prove that this configuration for the charge sensitive preamplifier permits an excellent noise performance at temperatures including room temperature. An equivalent noise charge of less than 20 electrons r.m.s. has been measured at room temperature by using a commercial JFET as input device of the preamplifier.

  19. Room-temperature single charge sensitivity in carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Peng, H. B.; Hughes, M. E.; Golovchenko, J. A.

    2006-12-01

    Electrical current fluctuation studies are reported for coaxial p-type and n-type single-wall carbon nanotube field-effect transistors (FETs). Abrupt discrete switching of the source-drain current is observed at room temperature. The authors attribute these random telegraph signals to charge fluctuating electron traps near the FET conduction channels. Evolution of the current-switching behavior associated with the occupancy of individual electron traps is demonstrated and analyzed statistically. The result strongly indicates room temperature single charge sensitivity in carbon nanotube FETs, which may offer potential applications for single molecule sensors based on suitably prepared FET devices.

  20. PULSE AMPLIFIER

    DOEpatents

    Johnstone, C.W.

    1958-06-17

    The improvement of pulse amplifiers used with scintillation detectors is described. The pulse amplifier circuit has the advantage of reducing the harmful effects of overloading cause by large signal inputs. In general the pulse amplifier circuit comprises two amplifier tubes with the input pulses applied to one amplifier grid and coupled to the second amplifier tube through a common cathode load. The output of the second amplifier is coupled from the plate circuit to a cathode follower tube grid and a diode tube in connected from grid to cathode of the cathode follower tube. Degenerative feedback is provided in the second amplifier by coupling a signal from the cathode follower cathode to the second amplifier grid. The circuit proqides moderate gain stability, and overload protection for subsequent pulse circuits.

  1. Intercellular Communication Amplifies Stressful Effects in High-Charge, High-Energy (HZE) Particle-Irradiated Human Cells

    PubMed Central

    AUTSAVAPROMPORN, Narongchai; DE TOLEDO, Sonia M.; BUONANNO, Manuela; JAY-GERIN, Jean-Paul; HARRIS, Andrew L.; AZZAM, Edouard I.

    2014-01-01

    Understanding the mechanisms that underlay the biological effects of particulate radiations is essential for space exploration and for radiotherapy. Here, we investigated the role of gap junction intercellular communication (GJIC) in modulating harmful effects induced in confluent cultures wherein most cells are traversed by one or more radiation tracks. We focused on the effect of radiation quality (linear energy transfer; LET) on junctional propagation of DNA damage and cell death among the irradiated cells. Confluent normal human fibroblasts were exposed to graded doses of 1 GeV protons (LET ~0.2 keV/μm) or 1 GeV/u iron ions (LET ~151 keV/μm) and were assayed for clonogenic survival and for micronucleus formation, a reflection of DNA damage, shortly after irradiation and following longer incubation periods. Iron ions were ~2.7 fold more effective than protons at killing 90% of the cells in the exposed cultures when assayed within 5–10 minutes after irradiation. When cells were held in the confluent state for several hours after irradiation, substantial repair of potentially lethal damage (PLDR), coupled with a reduction in micronucleus formation, occurred in cells exposed to protons, but not in those exposed to iron ions. In fact, such confluent holding after exposure to a similarly toxic dose of iron ions enhanced the induced toxic effect. However, following iron ion irradiation, inhibition of GJIC by 18-α-glycyrrhetinic acid eliminated the enhanced toxicity and reduced micronucleus formation to levels below those detected in cells assayed shortly after irradiation. The data show that low LET radiation induces strong PLDR within hours, but that high LET radiation with similar immediate toxicity does not induce PLDR and its toxicity increases with time following irradiation. The results also show that GJIC among irradiated cells amplifies stressful effects following exposure to high, but not LET radiation, and that GJIC has only minimal effect on cellular

  2. Parallel multilayer magnetoelectric composite based on (1-x)Pb(Mg1/3Nb2/3)-xPbTiO3 and Terfenol-D coupled with charge mode amplifier

    NASA Astrophysics Data System (ADS)

    Jiao, Jie; Li, Lingying; Ren, Bo; Guo, Hao; Deng, Hao; Di, Wenning; Zhao, Xiangyong; Jing, Weiping; Luo, Haosu

    2012-02-01

    In this paper, the sources and categories of noise regarding a charge mode magnetoelectric (ME) sensor are analyzed and simulated. A series of parallel multilayer magnetoelectric composites of Terfenol-D and (1-x)Pb(Mg1/3Nb2/3)-xPbTiO3 with different numbers of layers have been developed. The high magnetoelectric charge coefficients of these composites have been measured. By coupling different parallel multilayer magnetoelectric composites with a low noise-level charge amplifier, we found that the noise equivalent magnetic induction (NEB) of the ME sensor based on the charge mode is in accordance with the theoretical prediction, and multilayers can reduce the NEB at low frequency and hardly at high frequency. At last we have established a new method of using high g31 piezoelectric material that can effectively reduce the influence of the operational amplifier voltage noise component and enhance resolution.

  3. Charge generation by heavy ions in power MOSFETs, burnout space predictions, and dynamic SEB sensitivity

    NASA Astrophysics Data System (ADS)

    Stassinopoulos, E. G.; Brucker, G. J.; Calvel, P.; Baiget, A.; Peyrotte, C.; Gaillard, R.

    1992-12-01

    The transport, energy loss, and charge production of heavy ions in the sensitive regions of IRF 150 power MOSFETs are described. The dependence and variation of transport parameters with ion type and energy relative to the requirements for single event burnout in this part type are discussed. Test data taken with this power MOSFET are used together with analyses by means of a computer code of the ion energy loss and charge production in the device to establish criteria for burnout and parameters for space predictions. These parameters are then used in an application to predict burnout rates in a geostationary orbit for power converters operating in a dynamic mode. Comparisons of rates for different geometries in simulating SEU (single event upset) sensitive volumes are presented.

  4. Charge generation by heavy ions in power MOSFETs, burnout space predictions, and dynamic SEB sensitivity

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.; Brucker, G. J.; Calvel, P.; Baiget, A.; Peyrotte, C.; Gaillard, R.

    1992-01-01

    The transport, energy loss, and charge production of heavy ions in the sensitive regions of IRF 150 power MOSFETs are described. The dependence and variation of transport parameters with ion type and energy relative to the requirements for single event burnout in this part type are discussed. Test data taken with this power MOSFET are used together with analyses by means of a computer code of the ion energy loss and charge production in the device to establish criteria for burnout and parameters for space predictions. These parameters are then used in an application to predict burnout rates in a geostationary orbit for power converters operating in a dynamic mode. Comparisons of rates for different geometries in simulating SEU (single event upset) sensitive volumes are presented.

  5. Enhanced charge carrier generation in dye sensitized solar cells by nanoparticle plasmons

    NASA Astrophysics Data System (ADS)

    Hägglund, Carl; Zäch, Michael; Kasemo, Bengt

    2008-01-01

    An interesting possibility to improve the conversion and cost efficiencies of photovoltaic solar cells is to exploit the large optical cross sections of localized (nanoparticle) surface plasmon resonances (LSPRs). We have investigated this prospect for dye sensitized solar cells. Photoconductivity measurements were performed on flat TiO2 films, sensitized by a combination of dye molecules and arrays of nanofabricated elliptical gold disks. An enhanced dye charge carrier generation rate was found and shown to derive from the LSPR contribution by means of the polarization dependent resonance frequency in the anisotropic, aligned gold disks.

  6. Development of Charge Sensitive Infrared Phototransistors for the Far-Infrared Wavelength

    NASA Astrophysics Data System (ADS)

    Nihei, R.; Komiyama, S.; Kawada, M.; Matsuura, S.; Doi, Y.; Satoh, T.; Nakagawa, T.

    2014-08-01

    Ultra-highly-sensitive far-infrared detectors are developed for potential application to astronomy. The detectors exploit a novel mechanism called Charge Sensitive Infrared Phototransistors (CSIPs), in which an upper quantum well (QW) in GaAs/AlGaAs double QW structures is positively charged up by photo-excitation via inter-subband transition. This causes the conductance of the lower QW channel to increase. The device is effectively a phototransistor, in which the upper QW serves as a photo-sensitive gate to the source-drain channel provided by the lower QW. Resultant extraordinary high photoconductive gain makes CSIPs so sensitive as to detect single photons. CSIPs are well established in the mid-infrared ( = 12-20 m), achieving noise equivalent power around 1.9 10 W/Hz with a quantum efficiency of 7 %. CSIPs have been demonstrated to work in longer wavelengths up to 45 m, but the sensitivity was not as high as in the shorter wavelengths, probably due to lower quantum efficiency. Reported here is a remarkable improvement in the performance of longer wavelength CSIPs (45 m), achieved primarily by optimizing the doping concentration in the upper QW. This work indicates that longer wavelength CSIPs are promising detectors for the astronomical application.

  7. Ultrafast interfacial charge transfer dynamics in dye-sensitized and quantum dot solar cell

    NASA Astrophysics Data System (ADS)

    Ghosh, Hirendra N.

    2013-02-01

    Dye sensitized solar cell (DSSC) appeared to be one of the good discovery for the solution of energy problem. We have been involved in studying ultrafast interfacial electron transfer dynamics in DSSC using femtosecond laser spectroscopy. However it has been realized that it is very difficult to design and develop higher efficient one, due to thermodynamic limitation. Again in DSSC most of the absorbed photon energy is lost as heat within the cell, which apart from decreasing the efficiency also destabilizes the device. It has been realized that quantum dot solar cell (QDSC) are the best bet where the sensitizer dye molecules can be replaced by suitable quantum dot (QD) materials in solar cell. The quantum-confinement effect in semiconductors modifies their electronic structure, which is a very important aspect of these materials. For photovoltaic applications, a long-lived charge separation remains one of the most essential criteria. One of the problems in using QDs for photovoltaic applications is their fast charge recombination caused by nonradiative Auger processes, which occur predominantly at lower particle sizes due to an increase in the Coulomb interaction between electrons and holes. Various approaches, such as the use of metal-semiconductor composites, semiconductor-polymer composite, and semiconductor core-shell heterostructures, have been attempted to minimize the fast recombination between electrons and holes. To make higher efficient solar devices it has been realised that it is very important to understand charge carrier and electron transfer dynamics in QD and QD sensitized semiconductor nanostructured materials. In the present talk, we are going to discuss on recent works on ultrafast electron transfer dynamics in dye-sensitized TiO2 nanoparticles/film [1-12] and charge (electron/hole) transfer dynamics in quantum dot core-shell nano-structured materials [13-17].

  8. Sensitivity of Battery Electric Vehicle Economics to Drive Patterns, Vehicle Range, and Charge Strategies

    SciTech Connect

    Neubauer, J.; Brooker, A.; Wood, E.

    2012-07-01

    Battery electric vehicles (BEVs) offer the potential to reduce both oil imports and greenhouse gas emissions, but high upfront costs discourage many potential purchasers. Making an economic comparison with conventional alternatives is complicated in part by strong sensitivity to drive patterns, vehicle range, and charge strategies that affect vehicle utilization and battery wear. Identifying justifiable battery replacement schedules and sufficiently accounting for the limited range of a BEV add further complexity to the issue. The National Renewable Energy Laboratory developed the Battery Ownership Model to address these and related questions. The Battery Ownership Model is applied here to examine the sensitivity of BEV economics to drive patterns, vehicle range, and charge strategies when a high-fidelity battery degradation model, financially justified battery replacement schedules, and two different means of accounting for a BEV's unachievable vehicle miles traveled (VMT) are employed. We find that the value of unachievable VMT with a BEV has a strong impact on the cost-optimal range, charge strategy, and battery replacement schedule; that the overall cost competitiveness of a BEV is highly sensitive to vehicle-specific drive patterns; and that common cross-sectional drive patterns do not provide consistent representation of the relative cost of a BEV.

  9. Dual-Sensitive Charge-Conversional Polymeric Prodrug for Efficient Codelivery of Demethylcantharidin and Doxorubicin.

    PubMed

    Wu, Yanjuan; Zhou, Dongfang; Zhang, Qingfei; Xie, Zhigang; Chen, Xuesi; Jing, Xiabin; Huang, Yubin

    2016-08-01

    A tumor is a complicated system, and tumor cells are typically heterogeneous in many aspects. Polymeric drug delivery nanocarriers sensitive to a single type of biosignals may not release cargos effectively in all tumor cells, leading to low therapeutic efficacy. To address the challenges, here, we demonstrated a pH/reduction dual-sensitive charge-conversional polymeric prodrug strategy for efficient codelivery. Reduction-sensitive disulfide group and acid-labile anticancer drug (demethylcantharidin, DMC)-conjugated β-carboxylic amide group were repeatedly and regularly introduced into copolymer chain simultaneously via facile CuAAC click polymerization. The obtained multifunctional polymeric prodrug P(DMC), mPEG-b-poly(disulfide-alt-demethylcantharidin)-b-mPEG was further utilized for DOX encapsulation. Under tumor tissue/cell microenvironments (pH 6.5 and 10 mM GSH), the DOX-loaded polymeric prodrug nanoparticles (P(DMC)@DOX NPs) performed surface negative-to-positive charge conversion and accelerated/sufficient release of DMC and DOX. The remarkably enhanced cellular internalization and cytotoxicity in vitro, especially against DOX-resistant SMMC-7721 cells, were demonstrated. P(DMC)@DOX NPs in vivo also exhibited higher tumor accumulation and improved antitumor efficiency compared to P(SA)@DOX NPs with one drug and without charge-conversion ability. The desired multifunctional polymeric prodrug strategy brings a new opportunity for cancer chemotherapy. PMID:27384255

  10. Quantum squeezing and entanglement from a two-mode phase-sensitive amplifier via four-wave mixing in rubidium vapor

    NASA Astrophysics Data System (ADS)

    Fang, Yami; Jing, Jietai

    2015-02-01

    Phase-sensitive amplifiers (PSAs) have been widely studied in fiber amplifiers, with remarkable recent advances. They have also been implemented in an SU(1,1) interferometer. In this paper, we study an experimental scheme for the implementation of a two-mode PSA based on a four-wave mixing process in rubidium vapor. With the process seeded by coherent probe and conjugate beams, quantum correlation including intensity difference/sum squeezing and quadrature entanglement between the output probe and conjugate fields are theoretically analyzed. Compared to previous related research, several new and interesting results are reported here. The maximal degree of intensity difference squeezing can be enhanced by nearly 3 dB compared to a phase-insensitive amplifier with the same gain. It is also possible to generate intensity sum squeezing between the probe and conjugate fields by choosing the specific phase of the input beams. Moreover, quadrature entanglement between the probe and conjugate beams, which can be manipulated by the phase of the input beams, is predicted. Our scheme may find a variety of applications in quantum metrology and quantum information processing owing to its ability of quantum squeezing and entanglement manipulation.

  11. Factors limiting the sensitivity and dynamic range of a seismic system employing analog magnetic tape recording and a seismic amplifier with adjustable gain settings and several output levels

    USGS Publications Warehouse

    Eaton, Jerry P.; Van Schaack, John R.

    1977-01-01

    In the course of modernizing the low-speed-tape-recorder portable seismic systems and considering the possibilities for the design of a cassette-tape-recorder seismic refraction system, the factors that limit the sensitivity and dynamic range of such systems have been reviewed. These factors will first be stated briefly, and then their influence on systems such as the new 5-day-tape seismic system will be examined in more detail. To fix ideas, we shall assume that the system consists of the following elements: 1. A seismic sensor: usually a moving coil inertial seismometer with a period of about 1 second, a coil resistance of about 5000 ohms, and an effective motor constant of 1.0 V/cm/sec (across a 10K load terminating the seismometer sensitivity-and-damping-adjustment resistive network). 2. A seismic amplifier/voltage controlled oscillator unit made up of the following components: a) A fixed gain preamplifier with an input resistance of 10K and an internal noise level of 0.5 muVpp referred to the preamp input (0.1 Hz <= freq. <= 30 hz). b) An adjustable gain (0 to 42 db in 6 db steps) intermediate amplifier c) One or more fixed gain output amplifiers. d) Two sections of 6 db/octave bandpass filter serving to couple the 3 amplifier stages together. e) Voltage controlled oscillators for each output amplifier to produce modulated FM carriers for recording on separate tape tracks or modulated FM subcarriers for subsequent multiplexing and direct recording on tape in the California Network format. 3. An analog magnetic tape recorder: e.g. the PI 5100 (15/80 ips recording in the FM mode or in the direct mode with the 'broad-band' variant-of the Cal Net multiplex system, or 15/16 ips recording in the direct mode with the standard Cal Net multiplex system), or the Sony TC-126 cassette recorder operating in the direct record mode with the standard Cal Net multiplex system. 4. Appropriate magnetic tape playback equipment: e.g., the Bell and Howell 3700-B for the PI-5100 or

  12. High Speed Multichannel Charge Sensitive Data Acquisition System with Self-Triggered Event Timing

    PubMed Central

    Tremsin, Anton S.; Siegmund, Oswald H.W.; Vallerga, John V.; Raffanti, Rick; Weiss, Shimon; Michalet, Xavier

    2010-01-01

    A number of modern experiments require simultaneous measurement of charges on multiple channels at > MHz event rates with an accuracy of 100-1000 e− rms. One widely used data processing scheme relies on application of specific integrated circuits enabling multichannel analog peak detection asserted by an external trigger followed by a serial/sparsified readout. Although this configuration minimizes the back end electronics, its counting rate capability is limited by the speed of the serial readout. Recent advances in analog to digital converters and FPGA devices enable fully parallel high speed multichannel data processing with digital peak detection enhanced by finite impulse response filtering. Not only can accurate charge values be obtained at high event rates, but the timing of the event on each channel can also be determined with high accuracy. We present the concept and first experimental tests of fully parallel 128-channel charge sensitive data processing electronics capable of measuring charges with accuracy of ~1000 e- rms. Our system does not require an external trigger and, in addition to charge values, it provides the event timing with an accuracy of ~1 ns FWHM. One of the possible applications of this system is high resolution position sensitive event counting detectors with microchannel plates combined with cross strip readout. Implementation of fast data acquisition electronics increases the counting rates of those detectors to multi-MHz level, preserving their unique capability of virtually noiseless detection of both position (with accuracy of ~10 μm FWHM) and timing (~1 ns FWHM) of individual particles, including photons, electrons, ions, neutrals, and neutrons. PMID:20174482

  13. Charge transport through split photoelectrodes in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Fakharuddin, Azhar; Ahmed, Irfan; Khalidin, Zulkeflee; Yusoff, Mashitah M.; Jose, Rajan

    2014-04-01

    Charge transport and recombination are relatively ignored parameters while upscaling dye-sensitized solar cells (DSCs). Enhanced photovoltaic parameters are anticipated by merely widening the devices physical dimensions, viz., thickness and area as evident from the device design adopted in reported large area DSCs. These strip designs lead to ≤50% loss in photocurrent compared to the high efficiency lab scale devices. Herein, we report that the key to achieving higher current density (JSC) is optimized diffusion volume rather than the increased photoelectrode area because kinetics of the devices is strongly influenced by the varied choices of diffusion pathways upon increasing the electrode area. For a given electrode area and thickness, we altered the photoelectrode design by splitting the electrode into multiple fractions to restrict the electron diffusion pathways. We observed a correlation between the device physical dimensions and its charge collection efficiency via current-voltage and impedance spectroscopy measurements. The modified electrode designs showed >50% increased JSC due to shorter transport time, higher recombination resistance and enhanced charge collection efficiency compared to the conventional ones despite their similar active volume (˜3.36 × 10-4 cm3). A detailed charge transport characteristic of the split devices and their comparison with single electrode configuration is described in this article.

  14. Highly stable biased amplifier and stretcher system

    NASA Technical Reports Server (NTRS)

    Roddick, R. G.

    1970-01-01

    Amplifier and stretcher system, which minimizes thermal effects and compensates for repetition-rate effects, maintains resolution levels in spectrum analysis. An additional inverting amplifier is used in the system to provide a noiseless charge restorer.

  15. Visualizing interfacial charge transfer in dye sensitized nanoparticles using x-ray transient absorption spectroscopy.

    SciTech Connect

    Zhang, X. Y.; Smolentsev, G.; Guo, J.; Attenkofer, K.; Kurtz, C.; Jennings, G.; Lockard, J. V.; Stickrath, A. B.; Chen, L. X.

    2011-01-01

    A molecular level understanding of the structural reorganization accompanying interfacial electron transfer is important for rational design of solar cells. Here we have applied XTA (X-ray transient absorption) spectroscopy to study transient structures in a heterogeneous interfacial system mimicking the charge separation process in dye-sensitized solar cell (DSSC) with Ru(dcbpy){sub 2}(NCS){sub 2} (RuN3) dye adsorbed to TiO{sub 2} nanoparticle surfaces. The results show that the average Ru-NCS bond length reduces by 0.06 {angstrom}, whereas the average Ru-N(dcbpy) bond length remains nearly unchanged after the electron injection. The differences in bond-order change and steric hindrance between two types of ligands are attributed to their structural response in the charge separation. This study extends the application of XTA into optically opaque hybrid interfacial systems relevant to the solar energy conversion.

  16. Reduced sensitivity to charge noise in semiconductor spin qubits via symmetric operation

    NASA Astrophysics Data System (ADS)

    Reed, Matthew

    Gated semiconductor quantum dots controlled with the exchange interaction are attractive candidates for quantum information processing because of their long coherence time and electrical controllability. Exchange is conventionally modulated by detuning the chemical potentials of neighboring dots over a fixed tunnel barrier, an approach whose precision is limited by charge noise. In this talk we demonstrate a ''symmetric'' mode of operation which substantially reduces the sensitivity of exchange operations to gate fluctuations. The method involves biasing a double-dot symmetrically between the charge-state anti-crossings, where the derivative of the exchange energy with respect to gate voltages is minimized. Exchange remains highly tunable by adjusting the tunnel coupling. We propose a metric, insensitivity, to quantify the technique's improvement and find that it increases by at least a factor of five between operating regimes. We also demonstrate a substantial increase in the number of Rabi fringes observed.

  17. Ion induced charge collection and SEU sensitivity of emitter coupled logic (ECL) devices

    SciTech Connect

    Koga, R.; Crain, W.R.; Hansel, S.J.; Crawford, K.B.; Kirshman, J.F.; Pinkerton, S.D.; Penzin, S.H.; Moss, S.C.; Maher, M.

    1995-12-01

    This paper presents single event upset (SEU) and latchup test results for selected Emitter Coupled Logic (ECL) microcircuits, including several types of low capacity SRAMs and other memory devices. The high speed of ECL memory devices makes them attractive for use in space applications. However, the emitter coupled transistor design increases susceptibility to radiation induced functional errors, especially SEU, because the transistors are not saturated, unlike the transistors in a CMOS device. Charge collection at the sensitive nodes in ECL memory elements differs accordingly. These differences are responsible, in part, for the heightened SEU vulnerability of ECL memory devices relative to their CMOS counterparts.

  18. Enhanced response and sensitivity of self-corrugated graphene sensors with anisotropic charge distribution

    PubMed Central

    Yol Jeong, Seung; Jeong, Sooyeon; Won Lee, Sang; Tae Kim, Sung; Kim, Daeho; Jin Jeong, Hee; Tark Han, Joong; Baeg, Kang-Jun; Yang, Sunhye; Seok Jeong, Mun; Lee, Geon-Woong

    2015-01-01

    We introduce a high-performance molecular sensor using self-corrugated chemically modified graphene as a three dimensional (3D) structure that indicates anisotropic charge distribution. This is capable of room-temperature operation, and, in particular, exhibiting high sensitivity and reversible fast response with equilibrium region. The morphology consists of periodic, “cratered” arrays that can be formed by condensation and evaporation of graphene oxide (GO) solution on interdigitated electrodes. Subsequent hydrazine reduction, the corrugated edge area of the graphene layers have a high electric potential compared with flat graphene films. This local accumulation of electrons interacts with a large number of gas molecules. The sensitivity of 3D-graphene sensors significantly increases in the atmosphere of NO2 gas. The intriguing structures have several advantages for straightforward fabrication on patterned substrates, high-performance graphene sensors without post-annealing process. PMID:26053892

  19. Photoinduced charge transfer and acetone sensitivity of single-walled carbon nanotube-titanium dioxide hybrids.

    PubMed

    Ding, Mengning; Sorescu, Dan C; Star, Alexander

    2013-06-19

    The unique physical and chemical properties of single-walled carbon nanotubes (SWNTs) make them ideal building blocks for the construction of hybrid nanostructures. In addition to increasing the material complexity and functionality, SWNTs can probe the interfacial processes in the hybrid system. In this work, SWNT-TiO2 core/shell hybrid nanostructures were found to exhibit unique electrical behavior in response to UV illumination and acetone vapors. By experimental and theoretical studies of UV and acetone sensitivities of different SWNT-TiO2 hybrid systems, we established a fundamental understanding on the interfacial charge transfer between photoexcited TiO2 and SWNTs as well as the mechanism of acetone sensing. We further demonstrated a practical application of photoinduced acetone sensitivity by fabricating a microsized room temperature acetone sensor that showed fast, linear, and reversible detection of acetone vapors with concentrations in few parts per million range. PMID:23734594

  20. Enhanced response and sensitivity of self-corrugated graphene sensors with anisotropic charge distribution

    NASA Astrophysics Data System (ADS)

    Yol Jeong, Seung; Jeong, Sooyeon; Won Lee, Sang; Tae Kim, Sung; Kim, Daeho; Jin Jeong, Hee; Tark Han, Joong; Baeg, Kang-Jun; Yang, Sunhye; Seok Jeong, Mun; Lee, Geon-Woong

    2015-06-01

    We introduce a high-performance molecular sensor using self-corrugated chemically modified graphene as a three dimensional (3D) structure that indicates anisotropic charge distribution. This is capable of room-temperature operation, and, in particular, exhibiting high sensitivity and reversible fast response with equilibrium region. The morphology consists of periodic, “cratered” arrays that can be formed by condensation and evaporation of graphene oxide (GO) solution on interdigitated electrodes. Subsequent hydrazine reduction, the corrugated edge area of the graphene layers have a high electric potential compared with flat graphene films. This local accumulation of electrons interacts with a large number of gas molecules. The sensitivity of 3D-graphene sensors significantly increases in the atmosphere of NO2 gas. The intriguing structures have several advantages for straightforward fabrication on patterned substrates, high-performance graphene sensors without post-annealing process.

  1. Sensitivity evaluation of fiber optic OC-48 p-i-n transimpedance amplifier receivers using sweep-frequency modulation and intermixing diagnostics

    NASA Astrophysics Data System (ADS)

    Lin, Gong-Ru; Liao, Yu-Sheng

    2005-04-01

    The sensitivity of SONET p-i-n photodiode receivers with transimpedance amplifiers (PIN-TIA) from OC-3 to OC-48 data rates, measured by using a standard bit-error-rate tester (BERT) and a novel sweep-frequency-modulation/intermixing (SMIM) technique, are compared. A threshold intermixed voltage below 15.8 mV obtained by the SMIM method corresponding to the sensitivity of the PIN-TIA receiver beyond -32 dBm determined by BERT for the SONET OC-48 PIN-TIA receivers with a required BER of better than 10-10 is reported. The analysis interprets that the intermixed voltage for improving the PIN-TIA receiver sensitivity from -31 to -33 dBm has to be increased from 12.5 to 20.4 mV. As compared to the BERT, the SMIM is a relatively simplified, fast, and low-cost technique for on-line mass-production diagnostics for measuring the sensitivity and evaluating the BER performances of PIN-TIA receivers.

  2. Polyanions decelerate the kinetics of positively charged gramicidin channels as shown by sensitized photoinactivation.

    PubMed Central

    Antonenko, Yuri N; Borisenko, Vitali; Melik-Nubarov, Nikolay S; Kotova, Elena A; Woolley, G Andrew

    2002-01-01

    The effects of different anionic polymers on the kinetic properties of ionic channels formed by neutral gramicidin A (gA) and its positively charged analogs gramicidin-tris(2-aminoethyl)amine (gram-TAEA) and gramicidin-ethylenediamine (gram-EDA) in a bilayer lipid membrane were studied using a method of sensitized photoinactivation. The addition of Konig's polyanion caused substantial deceleration of the photoinactivation kinetics of gram-TAEA channels, which expose three positive charges to the aqueous phase at both sides of the membrane. In contrast, channels formed of gram-EDA, which exposes one positive charge, and neutral gA channels were insensitive to Konig's polyanion. The effect strongly depended on the nature of the polyanion added, namely: DNA, RNA, polyacrylic acid, and polyglutamic acid were inactive, whereas modified polyacrylic acid induced deceleration of the channel kinetics at high concentrations. In addition, DNA was able to prevent the action of Konig's polyanion. In single-channel experiments, the addition of Konig's polyanion resulted in the appearance of long-lived gram-TAEA channels. The deceleration of the gram-TAEA channel kinetics was ascribed to electrostatic interaction of the polyanion with gram-TAEA that reduces the mobility of gram-TAEA monomers and dimers in the membrane via clustering of channels. PMID:11867447

  3. DNA methylation levels analysis in four tissues of sea cucumber Apostichopus japonicus based on fluorescence-labeled methylation-sensitive amplified polymorphism (F-MSAP) during aestivation.

    PubMed

    Zhao, Ye; Chen, Muyan; Storey, Kenneth B; Sun, Lina; Yang, Hongsheng

    2015-03-01

    DNA methylation plays an important role in regulating transcriptional change in response to environmental stimuli. In the present study, DNA methylation levels of tissues of the sea cucumber Apostichopus japonicus were analyzed by the fluorescence-labeled methylation-sensitive amplified polymorphism (F-MSAP) technique over three stages of the aestivation cycle. Overall, a total of 26,963 fragments were amplified including 9112 methylated fragments among four sea cucumber tissues using 18 pairs of selective primers. Results indicated an average DNA methylation level of 33.79% for A. japonicus. The incidence of DNA methylation was different across tissue types in the non-aestivation stage: intestine (30.16%), respiratory tree (27.61%), muscle (27.94%) and body wall (56.25%). Our results show that hypermethylation accompanied deep-aestivation in A. japonicus, which suggests that DNA methylation may have an important role in regulating global transcriptional suppression during aestivation. Further analysis indicated that the main DNA modification sites were focused on intestine and respiratory tree tissues and that full-methylation but not hemi-methylation levels exhibited significant increases in the deep-aestivation stage. PMID:25461675

  4. Operational Amplifiers.

    ERIC Educational Resources Information Center

    Foxcroft, G. E.

    1986-01-01

    Addresses the introduction of low cost equipment into high school and college physical science classes. Examines the properties of an "ideal" operational amplifier and discusses how it might be used under saturated and non-saturated conditions. Notes the action of a "real" operational amplifier. (TW)

  5. Amplifier Distortion

    NASA Astrophysics Data System (ADS)

    Keeports, David

    2006-12-01

    By definition, a high fidelity amplifier's instantaneous output voltage is directly proportional to its instantaneous input voltage. While high fidelity is generally valued in the amplification of recorded music, nonlinearity, also known as distortion, is desirable in the amplification of some musical instruments. In particular, guitar amplifiers exploit nonlinearity to increase both the harmonic content and sustain of a guitar's sound. I will discuss how both modifications in sound result from saturation of triode tubes and transistors. Additionally, I will describe the difference in the symmetry of saturation curves for transistors and tubes and the reason why tube guitar amplifiers are generally considered to be superior to solid-state amplifiers. Finally, I will discuss attempts to use solid-state electronics to replicate the sound of tube amplifiers.

  6. Charge separation in solid-state dye-sensitized heterojunction solar cells

    SciTech Connect

    Bach, U.; Tachibana, Yasuhiro; Moser, J.E.; Haque, S.A.; Durrant, J.R.; Graetzel, M.; Klug, D.R.

    1999-08-18

    Dye-sensitized nanocrystalline solar cells are presently under intensive investigation, as they offer an attractive alternative to conventional p--n junction devices. Solid-state versions have been described where the electrolyte present in the pores of the malodorous oxide film is replaced by a large band gap p-type semiconductor. In this way, a solid-state heterojunction of very large contact area is formed. Light is absorbed by the dye that is located at the interface. Upon excitation, the dye injects electrons into the conduction band of the oxide and is regenerated by hole injection into the p-type conductor. High incident photon-to-electric current conversion efficiencies have been achieved recently with a cell consisting of a dye-derivatized mesoporous TiO{sub 2} film contacted by a new organic hole conductor. The great advantage of such systems with regard to conventional p--n junctions is that only majority carriers are involved in the photoelectric conversion process. Moreover, these are generated by the dye precisely at the site of the junction where the electric field is maximal, enhancing charge separation. Photoelectric conversion by conventional solar cells involves minority carriers whose lifetime is restricted due to recombination. As they are generated throughout the semiconductor and away from the junction, expensive high-purity materials are required in order to maintain the minority carrier diffusion length at a level where current losses are avoided. While the dynamics of photoinduced redo processes in photoelectrochemical systems have been studied in great detail, little is known about the electron-transfer dynamics in solid-state sensitized junctions. Here the authors report for the first time on the direct observation of photoinduced, interfacial charge separation across a dye-sensitized solid-state heterojunction by means of picosecond transient absorption laser spectroscopy.

  7. Physical inactivity amplifies the sensitivity of skeletal muscle to the lipid-induced downregulation of lipoprotein lipase activity.

    PubMed

    Zderic, Theodore W; Hamilton, Marc T

    2006-01-01

    Physical inactivity is a risk factor for lipoprotein disorders and the metabolic syndrome. Physical inactivity has a powerful effect on suppressing lipoprotein lipase (LPL) activity in skeletal muscle, the rate-limiting enzyme for hydrolysis of triglyceride (TG)-rich lipoproteins. We tested the ability of several compounds to prevent the decrease in LPL. The present study minimized standing and ordinary light nonexercise movements in rats to compare the effects of inactivity and nonexercise activity thermogenesis (NEAT) on LPL activity. The key new insight was that the typically quick decrease in LPL activity of oxidative muscle caused by physical inactivity was prevented by nicotinic acid (NA), whereas inhibitors of TNF-alpha, inducible nitric oxide synthase, and NF-kappaB had no such effect. NA was administered at a dose known to acutely impede the appearance of plasma TG from the liver and free fatty acids from adipose tissue, and it was effective at intentionally lowering plasma lipid concentrations to the same level in active and inactive groups. As measured from heparin-releasable LPL activity, LPL in the microvasculature of the most oxidative muscles was approximately 90% lower in the inactive group compared with controls, and this suppression was completely blocked by NA. In contrast to inactivity, NA did not raise muscle LPL in ambulatory controls, whereas a large exogenous fat delivery did decrease LPL activity. In vitro control studies revealed that NA did not have a direct effect on skeletal muscle LPL activity. In conclusion, physical inactivity amplifies the ability of plasma lipids to suppress muscle LPL activity. The light ambulatory contractions responsible for NEAT are sufficient for mitigating these deleterious effects. PMID:16195388

  8. Some characteristic features of the construction of the amplifying channel for working with semiconductor detectors in the charged particle energy spectrometer. [noise minimization at preamplifier input

    NASA Technical Reports Server (NTRS)

    Kuzyuta, E. I.

    1974-01-01

    A transistorized spectrometric amplifier with a shaper is reported that selects the shape of the frequency characteristic of the amplifying channel for which the primary frequency spectrum of the signal will pass, but where the noise spectrum is limited to the maximum. A procedure is presented for selecting the shaping circuits and their inclusion principles.

  9. DEPTH-CHARGE static and time-dependent perturbation/sensitivity system for nuclear reactor core analysis. Revision I. [DEPTH-CHARGE code

    SciTech Connect

    White, J.R.

    1985-04-01

    This report provides the background theory, user input, and sample problems required for the efficient application of the DEPTH-CHARGE system - a code black for both static and time-dependent perturbation theory and data sensitivity analyses. The DEPTH-CHARGE system is of modular construction and has been implemented within the VENTURE-BURNER computational system at Oak Ridge National Laboratory. The DEPTH module (coupled with VENTURE) solves for the three adjoint functions of Depletion Perturbation Theory and calculates the desired time-dependent derivatives of the response with respect to the nuclide concentrations and nuclear data utilized in the reference model. The CHARGE code is a collection of utility routines for general data manipulation and input preparation and considerably extends the usefulness of the system through the automatic generation of adjoint sources, estimated perturbed responses, and relative data sensitivity coefficients. Combined, the DEPTH-CHARGE system provides, for the first time, a complete generalized first-order perturbation/sensitivity theory capability for both static and time-dependent analyses of realistic multidimensional reactor models. This current documentation incorporates minor revisions to the original DEPTH-CHARGE documentation (ORNL/CSD-78) to reflect some new capabilities within the individual codes.

  10. Constant pressure-assisted head-column field-amplified sample injection in combination with in-capillary derivatization for enhancing the sensitivity of capillary electrophoresis.

    PubMed

    Yan, Na; Zhou, Lei; Zhu, Zaifang; Zhang, Huige; Zhou, Ximin; Chen, Xingguo

    2009-05-15

    In this work, a novel method combining constant pressure-assisted head-column field-amplified sample injection (PA-HC-FASI) with in-capillary derivatization was developed for enhancing the sensitivity of capillary electrophoresis. PA-HC-FASI uses an appropriate positive pressure to counterbalance the electroosmotic flow in the capillary column during electrokinetic injection, while taking advantage of the field amplification in the sample matrix and the water of the "head column". Accordingly, the analytes were stacked at the stationary boundary between water and background electrolyte. After 600s PA-HC-FASI, 4-fluoro-7-nitro-2,1,3-benzoxadiazole as derivatization reagent was injected, followed by an electrokinetic step (5kV, 45s) to enhance the mixing efficiency of analytes and reagent plugs. Standing a specified time of 10min for derivatization reaction under 35 degrees C, then the capillary temperature was cooled to 25 degrees C and the derivatives were immediately separated and determined under 25 degrees C. By investigating the variables of the presented approach in detail, on-line preconcentration, derivatization and separation could be automatically operated in one run and required no modification of current CE commercial instrument. Moreover, the sensitivity enhancement factor of 520 and 800 together with the detection limits of 16.32 and 6.34pg/mL was achieved for model compounds: glufosinate and aminomethylphosphonic acid, demonstrating the high detection sensitivity of the presented method. PMID:19342058

  11. A highly sensitive and selective fluorescent probe for fluoride anions based on intramolecular charge transfer.

    PubMed

    Liu, Jingkai; Xu, Zhenghe; Liu, Caiyun; Xu, Lirong; Wang, Zhongpeng; Zhu, Baocun

    2016-08-01

    Currently, there is a great need to develop methods for the selective detection of fluoride anions (F(-) ) owing to their toxicity in the environment and biological function in living systems. In this study, we developed a new fluorescent probe (probe 1) employing a Si-O bond as a highly selective recognition receptor for detecting F(-) via intramolecular charge transfer. Probe 1 could detect F(-) quantitatively using the turn-on fluorescence spectroscopy method with excellent sensitivity in the range of 4-38 μM and a detection limit of 0.26 μM; the detection time was < 17 min. We anticipate that probe 1 would be used widely to monitor F(-) in the environment. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26467672

  12. Ultra-low noise charge sensitive preamplifier for scintillation detection with avalanche photodiodes in PET applications

    SciTech Connect

    Schmitt, D.; Lecomte, R.; Lapointe, M.; Martel, G.; Carrier, C.; Karuta, B.; Duval, F.

    1987-02-01

    The need for compact, fast, low-noise front-end electronics in high resolution positron emission tomography (PET) has prompted this effort to design a preamplifier suitable for avalanche photodiode-based scintillation detectors. Due to the small signals from the detectors (< .03 rhoC/meV), a preamplifier with ultra-low noise performance in the 5 to 20 MHz range is essential to achieve the timing resolution required by the PET application. Out of many available technologies, a new third generation MOSFET was selected and implemented as input transistor in an original charge sensitive (CSP) design. Performance among the best reported to date are obtained. The new design was implemented as a dual-channel preamplifier in high density hybrid (thick film) technology.

  13. Isotope-Resolved and Charge-Sensitive Force Imaging Using Scanned Single Molecules

    NASA Astrophysics Data System (ADS)

    Sun, Yan; Rastawicki, Dominik; Liu, Yang; Mar, Warren; Manoharan, Hari; Miglio, Anna; Melinte, Sorin; Charlier, Jean-Christophe; Rignanese, Gian-Marco; He, Lianhua; Liu, Fang; Zhou, Aihui

    Originally conceived as surface imaging instruments, the scanning tunnelling microscope (STM) and the atomic force microscope (AFM) were recently used to probe molecular chemical bonds with exquisite sensitivity. Remarkably, molecule-functionalized scanning tips can also provide direct access to the inelastic electron tunneling spectrum (IETS) of the terminal molecule. Here we report atomic manipulation experiments addressing carbon monoxide (CO) isotopes at low temperatures. The unique and quantifiable dependence of the CO vibrational modes offers insight into tip-controlled force and charge sensing of surface adsorbates, subsurface defects, and quantum nanostructures. The specific behavior of the monitored vibrational modes originates from the interplay of interaction forces between the top electrode--a scanned tip functionalized with a single molecule--and the atomic scale force field surrounding the target atomically-assembled nanostructure. We also present density functional theory (DFT) computations that have been performed in order to scrutinize and visualize the vibrational spectroscopic fingerprints and local force fields.

  14. Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole-NiO dye sensitized solar cells.

    PubMed

    Zhang, Lei; Favereau, Ludovic; Farré, Yoann; Mijangos, Edgar; Pellegrin, Yann; Blart, Errol; Odobel, Fabrice; Hammarström, Leif

    2016-07-21

    In a photophysical study, two diketopyrrolopyrrole (DPP)-based sensitizers functionalized with 4-thiophenecarboxylic acid as an anchoring group and a bromo (DPPBr) or dicyanovinyl (DPPCN2) group, and a dyad consisting of a DPP unit linked to a naphthalenediimide group (DPP-NDI), were investigated both in solution and grafted on mesoporous NiO films. Femtosecond transient absorption measurements indicate that ultrafast hole injection occurred predominantly on a timescale of ∼200 fs, whereas the subsequent charge recombination occurred on a surprisingly wide range of timescales, from tens of ps to tens of μs; this kinetic heterogeneity is much greater than is typically observed for dye-sensitized TiO2 or ZnO. Also, in contrast to what is typically observed for dye-sensitized TiO2, there was no significant dependence on the excitation power of the recombination kinetics, which can be explained by the hole density being comparatively higher near the valence band of NiO before excitation. The additional acceptor group in DPP-NDI provided a rapid electron shift and stabilized charge separation up to the μs timescale. This enabled efficient (∼95%) regeneration of NDI by a Co(III)(dtb)3 electrolyte (dtb = 4,4'-di-tert-butyl-2,2'-bipyridine), according to transient absorption measurements. The regeneration of DPPBr and DPPCN2 by Co(III)(dtb)3 was instead inefficient, as most recombination for these dyes occurred on the sub-ns timescale. The transient spectroscopy data thus corroborated the trend of the published photovoltaic properties of dye-sensitized solar cells (DSSCs) based on these dyes on mesoporous NiO, and show the potential of a design strategy with a secondary acceptor bound to the dye. The study identifies rapid initial recombination between the dye and NiO as the main obstacle to obtaining high efficiencies in NiO-based DSSCs; these recombination components may be overlooked when studies are conducted using only methods with ns resolution or slower. PMID

  15. Gyromagnetron amplifier

    SciTech Connect

    Lau, Y.-Y.; Barnett, L. R.

    1985-10-29

    A gyromagnetron amplifier for radiation at millimeter wavelengths comprising a tapered waveguide tube with longitudinally running vanes in the walls of the tube with the number of vanes chosen to coincide with a desired cyclotron harmonic frequency to be amplified. A beam of spiralling mildly relativistic electrons with an energy of 100 keV or less is directed into the small end of the tapered waveguide tube. A tapered axial magnetic field is set up within the waveguide tube with a low value appropriate to the amplification of a cyclotron harmonic frequency. An electromagnetic wave to be amplified is launched into the waveguide tube to co-propagate and be amplified by the spiralling electron beam. This device is characterized by a wide bandwidth, a low operating magnetic field, a relatively low operating beam voltage, with high power, and the capability of continuous wave operation.

  16. Enhanced performance CCD output amplifier

    DOEpatents

    Dunham, Mark E.; Morley, David W.

    1996-01-01

    A low-noise FET amplifier is connected to amplify output charge from a che coupled device (CCD). The FET has its gate connected to the CCD in common source configuration for receiving the output charge signal from the CCD and output an intermediate signal at a drain of the FET. An intermediate amplifier is connected to the drain of the FET for receiving the intermediate signal and outputting a low-noise signal functionally related to the output charge signal from the CCD. The amplifier is preferably connected as a virtual ground to the FET drain. The inherent shunt capacitance of the FET is selected to be at least equal to the sum of the remaining capacitances.

  17. Sensitive detection of acetylcholine based on a novel boronate intramolecular charge transfer fluorescence probe.

    PubMed

    Liu, Chang; Shen, Youming; Yin, Peng; Li, Lidong; Liu, Meiling; Zhang, Youyu; Li, Haitao; Yao, Shouzhuo

    2014-11-15

    A highly sensitive and selective fluorescence method for the detection of acetylcholine (ACh) based on enzyme-generated hydrogen peroxide (H2O2) and a new boronate intramolecular charge transfer (ICT) fluorescence probe, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-N-butyl-1,8-naphthalimide (BN), was developed. This strategy involves the reaction of ACh with acetylcholinesterase (AChE) to produce choline, which is further oxidized by choline oxidase (ChOx) to obtain betaine and H2O2. The enzyme-generated H2O2 reacts with BN and results in hydrolytic deprotection of BN to generate fluorescent product (4-hydroxyl-N-butyl-1,8-naphthalimide, ON). Two consecutive linear response ranges allow determining ACh in a wide concentration range with a low detection limit of 2.7 nM (signal/noise=3). Compared with other fluorescent probes based on the mechanism of nonspecific oxidation, this reported boronate probe has the advantage of no interference from other biologically relevant reactive oxygen species (ROS) on the detection of ACh. This study provides a new method for the detection of ACh with high selectivity and sensitivity. PMID:25132563

  18. Enhanced charge collection in dye-sensitized solar cells utilizing collector-shell electrodes

    NASA Astrophysics Data System (ADS)

    Xiao, Manda; Huang, Fuzhi; Xiang, Wanchun; Cheng, Yi-Bing; Spiccia, Leone

    2015-03-01

    Nanostructured porous tin-doped indium oxide (ITO) films were prepared by screen printing of an ITO nanoparticle paste onto conducting fluorine-doped tin oxide (FTO) substrates. The ITO films were subsequently coated with thin layers of TiO2 by the hydrolysis of TiCl4 to form the collector-shell photoelectrodes. The morphology of films was analysed by scanning electron microscope (SEM). It was found that a uniform coating of TiO2 was achieved when three or more deposition cycles were applied. Dye-sensitized solar cells were constructed with the collector-shell photoelectrodes using an electrolyte containing the [Co(bpy)3]2+/3+ (bpy = 2,2‧-bipyridine) redox couple and MK-2, an organic sensitizer and efficiencies of 3.3% achieved. Charge transport in cells utilizing the collector-shell electrodes was found to be 2-6 times faster than those utilizing P25-based TiO2 electrodes.

  19. Sensitive fiber optics-based system for real-time detection of PCR-amplified DNA using molecular beacons

    NASA Astrophysics Data System (ADS)

    Reid, Taylor A.; Cayouette, Michelle; Brown, Larry; Mousavi, Ali R.; Slaney, John; Moores, Jane

    1999-05-01

    Molecular Beacon hairpin shaped fluorescent oligonucleotide probes are powerful tools for quantifying specific nucleic acid sequences. Stratagene is developing a sensitive system, using these probes, for detecting and quantifying initial template copy number of nucleic acid sequences in real time during PCR amplification. The system allows parallel multiple fluorophore detection for many applications including allele discrimination and quantitative gene expression analysis. This instrument, combined with Stratagene's Sentinel Molecular Beacon kits, provides an effective system for molecular biology research. We report here the design and utility of an instrument that combines the capabilities of a microplate fluorescence reader with a PCR thermocycler into a low cost real time detection system. The instrument integrates a multiple fluorophore parallel fiber optic excitation and emission detection system, a precision X-Y translation stage, and a high performance thermoelectric temperature cycler with a computer controlled data collection and analysis system. The system uses standard PCR tubes, tube strips, and 96 well plates as the sample format. The result is a low cost, reliable, and easy to use system with premium performance for nucleic acid quantification in real time. 10

  20. Optical Transitions in Highly Charged Californium Ions with High Sensitivity to Variation of the Fine-Structure Constant

    NASA Astrophysics Data System (ADS)

    Berengut, J. C.; Dzuba, V. A.; Flambaum, V. V.; Ong, A.

    2012-08-01

    We study electronic transitions in highly charged Cf ions that are within the frequency range of optical lasers and have very high sensitivity to potential variations in the fine-structure constant, α. The transitions are in the optical range despite the large ionization energies because they lie on the level crossing of the 5f and 6p valence orbitals in the thallium isoelectronic sequence. Cf16+ is a particularly rich ion, having several narrow lines with properties that minimize certain systematic effects. Cf16+ has very large nuclear charge and large ionization energy, resulting in the largest α sensitivity seen in atomic systems. The lines include positive and negative shifters.

  1. LOGARITHMIC AMPLIFIER

    DOEpatents

    Wade, E.J.; Stone, R.S.

    1959-03-10

    Electronic,amplifier circuits, especially a logai-ithmic amplifier characterizxed by its greatly improved strability are discussed. According to the in ention, means are provided to feed bach the output valtagee to a diode in the amplifier input circuit, the diode being utilized to produce the logarithmic characteristics. The diode is tics, The diode isition therewith and having its filament operated from thc same source s the filament of the logarithmic diode. A bias current of relatively large value compareii with the signal current is continuously passed through the compiting dioie to render the diode insensitivy to variations in the signal current. by this odes kdu to variaelled, so that the stability of the amlifier will be unimpaired.

  2. Bidirectional amplifier

    DOEpatents

    Wright, James T.

    1986-01-01

    A bilateral circuit is operable for transmitting signals in two directions without generation of ringing due to feedback caused by the insertion of the circuit. The circuit may include gain for each of the signals to provide a bidirectional amplifier. The signals are passed through two separate paths, with a unidirectional amplifier in each path. A controlled sampling device is provided in each path for sampling the two signals. Any feedback loop between the two signals is disrupted by providing a phase displacement between the control signals for the two sampling devices.

  3. Bidirectional amplifier

    DOEpatents

    Wright, J.T.

    1984-02-02

    A bilateral circuit is operable for transmitting signals in two directions without generation of ringing due to feedback caused by the insertion of the circuit. The circuit may include gain for each of the signals to provide a bidirectional amplifier. The signals are passed through two separate paths, with a unidirectional amplifier in each path. A controlled sampling device is provided in each path for sampling the two signals. Any feedback loop between the two signals is disrupted by providing a phase displacement between the control signals for the two sampling devices.

  4. Ce-based metal-organic frameworks and DNAzyme-assisted recycling as dual signal amplifiers for sensitive electrochemical detection of lipopolysaccharide.

    PubMed

    Shen, Wen-Jun; Zhuo, Ying; Chai, Ya-Qin; Yuan, Ruo

    2016-09-15

    In this work, a sensitive electrochemical aptasensor was designed for lipopolysaccharide (LPS) detection based on Ce-based metal-organic frameworks (Ce-MOFs) and Zn(2+) dependent DNAzyme-assisted recycling as dual signal amplifiers. Herein, Ce-MOFs were decorated with gold nanoparticles (AuNPs) to obtain AuNPs/Ce-MOFs, and the resultant AuNPs/Ce-MOFs not only acted as nanocarriers to capture -SH terminated hairpin probes 2 (HP2) for acquiring HP2/AuNPs/Ce-MOFs signal probes, but also as catalysts to catalyze the oxidation of ascorbic acid (AA). In the presence of target LPS, report DNA was released from the prepared duplex DNA and then hybridized with hairpin probes 1 (HP1, which were immobilized on the electrode). With the help of Zn(2+), report DNA could act as Zn(2+) dependent DNAzyme to cleave HP1 circularly. Then a large amount of capture probes were produced on the electrode to combine with HP2/AuNPs/Ce-MOFs signal probes. When the detection solution contained electrochemical substrate of AA, AuNPs/Ce-MOFs could oxide AA to obtain enhanced signal. Under the optimized conditions, this proposed aptasensor for LPS exhibited a low detection limit of 3.3 fg/mL with a wide linear range from 10fg/mL to 100ng/mL. PMID:27132003

  5. Amplified Policymaking

    ERIC Educational Resources Information Center

    Prince, Katherine; Woempner, Carolyn

    2010-01-01

    This brief examines the policy implications of two drivers of change presented in the "2020 Forecast: Creating the Future of Learning"-- Pattern Recognition and Amplified Organization. These drivers point toward a series of cultural shifts and illuminate how we are developing new ways of organizing, constructing, and managing knowledge.…

  6. Performance of resistive-charge position sensitive detectors for RBS/Channeling applications

    NASA Astrophysics Data System (ADS)

    Miranda, P. A.; Wahl, U.; Catarino, N.; Ribeiro da Silva, M.; Alves, E.

    2014-10-01

    The performance of two types of 1×1 cm2 photodiode position sensitive detectors (PSDs) based on resistive charge division was evaluated for their use in Rutherford Backscattering/Channeling (RBS/C) experiments in blocking geometry. Their energy resolution was first determined for ~ 5.5 MeV alpha particles from a radioactive sources, and values of full width half maximum (FWHM) of 22 keV and 33 keV were achieved using a shaping time constant of τ = 2.0 μs. Additional tests were performed using backscattered 4He particles from the 2.0 MeV beam of a Van de Graaff accelerator. While the 22 keV FWHM detector failed after exposure to less than 5×106 cm-24He particles, the other did not show any noticeable deterioration due to radiation damage for a fluence of 4×108 cm-2. For this type of PSD position resolution (τ = 0.5 μs) standard deviations of ΔL = 0.072 mm at ~ 5.5 MeV and ΔL = 0.247 mm at 1.1 MeV were achieved. RBS/Channeling experiments using PSD were performed on several crystalline samples, showing that this setup seems suitable for lattice location studies, particularly for heavy ions implantation (D ≳1015 at /cm2) on light substrates like Si, SiC, and AlN.

  7. Transient 2D IR spectroscopy of charge injection in dye-sensitized nanocrystalline thin films.

    PubMed

    Xiong, Wei; Laaser, Jennifer E; Paoprasert, Peerasak; Franking, Ryan A; Hamers, Robert J; Gopalan, Padma; Zanni, Martin T

    2009-12-23

    We use nonlinear 2D IR spectroscopy to study TiO(2) nanocrystalline thin films sensitized with a Re dye. We find that the free electron signal, which often obscures the vibrational features in the transient absorption spectrum, is not observed in the 2D IR spectra. Its absence allows the vibrational features of the dye to be much better resolved than with the typical IR absorption probe. We observe multiple absorption bands but no cross peaks in the 2D IR spectra, which indicates that the dyes have at least three conformations. Furthermore, by using a pulse sequence in which we initiate electron transfer in the middle of the infrared pulse train, we are able to assign the excited state features by correlating them to the ground state vibrational modes and determine that the three conformations have different time scales and cross sections for electron injection. 2D IR spectroscopy is proving to be very useful in disentangling overlapping structural distributions in biological and chemical physics processes. These experiments demonstrate that nonlinear infrared probes are also a powerful new tool for studying charge transfer at interfaces. PMID:19947603

  8. Highly selective and sensitive adenosine aptasensor based on platinum nanoparticles as catalytical label for amplified detection of biorecognition events through H2O2 reduction.

    PubMed

    Shahdost-fard, Faezeh; Salimi, Abdollah; Khezrian, Somayeh

    2014-03-15

    Based on a combination of aptamer and platinum nanoparticles a new sensitive and selective adenosine aptasensor was fabricated. Functionalized thiol-terminated adenosine aptamer (5'-AGAGAACCTGGGGGAGTATTGCGGAGGAAGGT-SH-3') with Pt Nanoparticles (Pt-NPs) was employed as highly catalytic label for electrochemical detection of adenosine based on electrocatalytic activity of Pt-NPs toward H2O2 reduction. Multiwalled carbon nanotubes/ionic liquid/chitosan (MWCNTs/IL/CHIT) nanocomposite was applied as the interface for covalent attachment of 3'-amine-terminated capture probe (3'-NH2-(CH2)6-TCTCTTGGACCC-5'). The presence of Pt nanoparticles improvement the conductivity and performance characteristics of the biosensor as well as incensement in the loading amount of the aptamer DNA sequence. The interaction of adenosine with the aptamer causes the releasing of aptamer with PtNPs into solution which resulted in a decreasing of hydrogen peroxide reduction peak current. Sensitive quantitative detection of adenosine was achieved by monitoring the decrease of voltammetric responses of H2O2 peak current. The peak current of H2O2 decreased with increase in the concentration of adenosine over a range of 1-750 nM with detection limit 1 nM. In addition the proposed aptasensor showed excellent selectivity toward adenosine in compared to some other nucleosides such as guanosine, cytidine and uridine. The proposed aptasensor was successfully used to detect adenosine in human serum samples. The elimination of enzymes or antibodies for the amplified detection of adenosine and the use of platinum nanoparticles as inorganic catalytic label, are the advantage of the proposed aptasensor. PMID:24176972

  9. A nonconjugated bridge in dimer-sensitized solar cells retards charge recombination without decreasing charge injection efficiency.

    PubMed

    Sunahara, Kenji; Griffith, Matthew J; Uchiyama, Takayuki; Wagner, Pawel; Officer, David L; Wallace, Gordon G; Mozer, Attila J; Mori, Shogo

    2013-11-13

    Dye sensitized solar cells (DSSCs) employing a dimer porphyrin, which was synthesised with two porphyrin units connected without conjugation, have shown that both porphyrin components can contribute to photocurrent generation, that is, more than 50 % internal quantum efficiency. In addition, the open-circuit voltage (Voc) of the DSSCs was higher than that of DSSCs using monomer porphyrins. In this paper, we first optimized cell structure and fabrication conditions. We obtained more than 80% incident photon to current conversion efficiency from the dimer porphyrin sensitized DSSCs and higher Voc and energy conversion efficiency than monomer porphyrin sensitized solar cells. To examine the origin of the higher Voc, we measured electron lifetime in the DSSCs with various conditions, and found that the dimer system increased the electron lifetime by improving the steric blocking effect of the dye layer, whilst the lack of a conjugated linker prevents an increase in the attractive force between conjugated sensitizers and the acceptor species in the electrolyte. The results support a hypothesis; dispersion force is one of the factors influencing the electron lifetime in DSSCs. PMID:24188005

  10. Angular sensitivity of modeled scientific silicon charge-coupled devices to initial electron direction

    NASA Astrophysics Data System (ADS)

    Plimley, Brian; Coffer, Amy; Zhang, Yigong; Vetter, Kai

    2016-08-01

    Previously, scientific silicon charge-coupled devices (CCDs) with 10.5-μm pixel pitch and a thick (650 μm), fully depleted bulk have been used to measure gamma-ray-induced fast electrons and demonstrate electron track Compton imaging. A model of the response of this CCD was also developed and benchmarked to experiment using Monte Carlo electron tracks. We now examine the trade-off in pixel pitch and electronic noise. We extend our CCD response model to different pixel pitch and readout noise per pixel, including pixel pitch of 2.5 μm, 5 μm, 10.5 μm, 20 μm, and 40 μm, and readout noise from 0 eV/pixel to 2 keV/pixel for 10.5 μm pixel pitch. The CCD images generated by this model using simulated electron tracks are processed by our trajectory reconstruction algorithm. The performance of the reconstruction algorithm defines the expected angular sensitivity as a function of electron energy, CCD pixel pitch, and readout noise per pixel. Results show that our existing pixel pitch of 10.5 μm is near optimal for our approach, because smaller pixels add little new information but are subject to greater statistical noise. In addition, we measured the readout noise per pixel for two different device temperatures in order to estimate the effect of temperature on the reconstruction algorithm performance, although the readout is not optimized for higher temperatures. The noise in our device at 240 K increases the FWHM of angular measurement error by no more than a factor of 2, from 26° to 49° FWHM for electrons between 425 keV and 480 keV. Therefore, a CCD could be used for electron-track-based imaging in a Peltier-cooled device.

  11. Differential transimpedance amplifier circuit for correlated differential amplification

    DOEpatents

    Gresham, Christopher A.; Denton, M. Bonner; Sperline, Roger P.

    2008-07-22

    A differential transimpedance amplifier circuit for correlated differential amplification. The amplifier circuit increase electronic signal-to-noise ratios in charge detection circuits designed for the detection of very small quantities of electrical charge and/or very weak electromagnetic waves. A differential, integrating capacitive transimpedance amplifier integrated circuit comprising capacitor feedback loops performs time-correlated subtraction of noise.

  12. Determination of DNA methylation associated with Acer rubrum (red maple) adaptation to metals: analysis of global DNA modifications and methylation-sensitive amplified polymorphism.

    PubMed

    Kim, Nam-Soo; Im, Min-Ji; Nkongolo, Kabwe

    2016-08-01

    Red maple (Acer rubum), a common deciduous tree species in Northern Ontario, has shown resistance to soil metal contamination. Previous reports have indicated that this plant does not accumulate metals in its tissue. However, low level of nickel and copper corresponding to the bioavailable levels in contaminated soils in Northern Ontario causes severe physiological damages. No differentiation between metal-contaminated and uncontaminated populations has been reported based on genetic analyses. The main objective of this study was to assess whether DNA methylation is involved in A. rubrum adaptation to soil metal contamination. Global cytosine and methylation-sensitive amplified polymorphism (MSAP) analyses were carried out in A. rubrum populations from metal-contaminated and uncontaminated sites. The global modified cytosine ratios in genomic DNA revealed a significant decrease in cytosine methylation in genotypes from a metal-contaminated site compared to uncontaminated populations. Other genotypes from a different metal-contaminated site within the same region appear to be recalcitrant to metal-induced DNA alterations even ≥30 years of tree life exposure to nickel and copper. MSAP analysis showed a high level of polymorphisms in both uncontaminated (77%) and metal-contaminated (72%) populations. Overall, 205 CCGG loci were identified in which 127 were methylated in either outer or inner cytosine. No differentiation among populations was established based on several genetic parameters tested. The variations for nonmethylated and methylated loci were compared by analysis of molecular variance (AMOVA). For methylated loci, molecular variance among and within populations was 1.5% and 13.2%, respectively. These values were low (0.6% for among populations and 5.8% for within populations) for unmethylated loci. Metal contamination is seen to affect methylation of cytosine residues in CCGG motifs in the A. rubrum populations that were analyzed. PMID:27547351

  13. An FET-type charge sensor for highly sensitive detection of DNA sequence.

    PubMed

    Kim, Dong-Sun; Jeong, Yong-Taek; Park, Hey-Jung; Shin, Jang-Kyoo; Choi, Pyung; Lee, Jong-Hyun; Lim, Geunbae

    2004-07-30

    We have fabricated an field effect transistor (FET)-type DNA charge sensor based on 0.5 microm standard complementary metal oxide semiconductor (CMOS) technology which can detect the deoxyribonucleic acid (DNA) probe's immobilization and information on hybridization by sensing the variation of drain current due to DNA charge and investigated its electrical characteristics. FET-type charge sensor for detecting DNA sequence is a semiconductor sensor measuring the change of electric charge caused by DNA probe's immobilization on the gate metal, based on the field effect mechanism of MOSFET. It was fabricated in p-channel (P) MOSFET-type because the phosphate groups present in DNA have a negative charge and this charge determines the effective gate potential of PMOSFET. Gold (Au) which has a chemical affinity with thiol was used as the gate metal in order to immobilize DNA. The gate potential is determined by the electric charge which DNA possesses. Variation of the drain current versus time was measured. The drain current increased when thiol DNA and target DNA were injected into the solution, because of the field effect due to the electrical charge of DNA molecules. The experimental validity was verified by the results of mass changes detected using quartz crystal microbalance (QCM) under the same measurement condition. Therefore it is confirmed that DNA sequence can be detected by measuring the variation of the drain current due to the variation of DNA charge and the proposed FET-type DNA charge sensor might be useful in the development for DNA chips. PMID:15142578

  14. Injectable Hydrogel: Amplifying the pH Sensitivity of a Triblock Copolypeptide by Conjugating the N-Termini via Dynamic Covalent Bonding.

    PubMed

    Popescu, Maria-Teodora; Liontos, George; Avgeropoulos, Apostolos; Voulgari, Efstathia; Avgoustakis, Konstantinos; Tsitsilianis, Constantinos

    2016-07-13

    We explore the self-assembly behavior of aqueous solutions of an amphiphilic, pH-sensitive poly(l-alanine)-b-poly(l-glutamic acid)-b-poly(l-alanine), (A5E11A5) triblock copolypeptide, end-capped by benzaldehyde through Schiff base reaction. At elevated concentrations and under physiological pH (7.4) and ionic strength (0.15M), the bare copolypeptide aqueous solutions underwent a sol-gel transition after heating and slow cooling thermal treatment, forming opaque stiff gels due to a hierarchical self-assembly that led to the formation of β-sheet-based twisted super fibers (Popescu et al. Soft Matter 2015, 11, 331-342). The conjugation of the N-termini with benzaldehyde (Bz) through a Schiff base reaction amplifies the copolypeptide pH-sensitivity within a narrow pH window relevant for in vivo applications. Specifically, the dynamic character of the imine bond allowed coupling/decoupling of the Bz upon switching pH. The presence of Bz conjugates to the N-termini of the copolypeptide resulted in enhanced packing of the elementary superfibers into thick and short piles, which inhibited the ability of the system for gelation. However, partial cleavage of Bz upon lowering pH to 6.5 prompted recovery of the hydrogel. The sol-gel transition triggered by pH was reversible, due to the coupling/decoupling of the benzoic-imine dynamic covalent bonding, endowing thus the gelling system with injectability. Undesirably, the gelation temperature window was significantly reduced, which however can be regulated at physiological temperatures by using a suitable mixture of the bare and the Bz-conjugated coplypeptide. This triblock copolypeptide gelator was investigated as a scaffold for the encapsulation of polymersome nanocarriers, loaded with a hydrophilic model drug, calcein. The polymersome/polypeptide complex system showed prolonged probe release in pH 6.5, which is relevant to extracellular tumor environment, rendering the system potentially useful for sustained delivery of

  15. Charge-conversional and pH-sensitive PEGylated polymeric micelles as efficient nanocarriers for drug delivery.

    PubMed

    Liu, Gong-Yan; Li, Min; Zhu, Cong-Shan; Jin, Qiao; Zhang, Zong-Cai; Ji, Jian

    2014-09-01

    A novel amphiphilic copolymer, poly (ethylene glycol)-graft-polyethyleneimine/amide (PEG-g-PEI/amide), is synthesized by grafting PEG and1,2-cis-Cyclohexanedicarboxylic anhydride onto the PEI. PEGylated polymeric micelles can be assembled from the amphiphilic copolymers with well-defined nano-sizes, and anti-cancer drugs are successfully loaded into micelle core formed by the amide. The amides with neighboring carboxylic acid groups exhibit pH-dependent hydrolysis and can reversibly shield the cationic charge of amine groups on the PEI, giving the micelles a charge-conversion property from negative to positive in acidic tumor tissue environment. Meanwhile, the cleavage of amide bonds at acidic pH also results in the disassembly of the micelle and pH-responsive drug release. These micelles are promising drug delivery systems due to their smart properties: PEGylation, suitable size, charge-conversion, and simultaneous pH-sensitive drug release. PMID:24866398

  16. Optical transitions in highly charged californium ions with high sensitivity to variation of the fine-structure constant.

    PubMed

    Berengut, J C; Dzuba, V A; Flambaum, V V; Ong, A

    2012-08-17

    We study electronic transitions in highly charged Cf ions that are within the frequency range of optical lasers and have very high sensitivity to potential variations in the fine-structure constant, α. The transitions are in the optical range despite the large ionization energies because they lie on the level crossing of the 5f and 6p valence orbitals in the thallium isoelectronic sequence. Cf(16+) is a particularly rich ion, having several narrow lines with properties that minimize certain systematic effects. Cf(16+) has very large nuclear charge and large ionization energy, resulting in the largest α sensitivity seen in atomic systems. The lines include positive and negative shifters. PMID:23006353

  17. Carboxymethyl Chitosan-Modified Polyamidoamine Dendrimer Enables Progressive Drug Targeting of Tumors via pH-Sensitive Charge Inversion.

    PubMed

    Qi, Xiaole; Qin, Jiayi; Fan, Yuchao; Qin, Xiaoxue; Jiang, Yujie; Wu, Zhenghong

    2016-04-01

    Polyamidoamine dendrimers are potential candidates for drug delivery systems due to their remarkable cell-penetrating power that results from their strong positive surface charge. However, the positively charged surfaces always lead to serious cytotoxicity and the rapid clearance of polyamidoamine in vivo, which limit the application of these dendrimers. To overcome these drawbacks, we developed a carboxymethyl chitosan-modified polyamidoamine dendrimer to achieve progressive drug targeting of tumors via pH-sensitive charge inversion. With the shielding of carboxymethyl chitosan, the complex was negatively charged at physiological conditions (pH 7.4) and prone to enrich at tumor sites due to the enhanced permeation and retention effect; however, it regained a positive charge via the removal of the carboxymethyl chitosan coating under tumor-acidic conditions (pH 6.5) and achieved high intracellular uptake in tumor cells through electrostatic adsorptive endocytosis. In this study, these dendrimers exhibited 1.99- and 1.76-times higher cellular uptake efficiencies at pH 7.4 in MCF-7 or A549 cells, respectively, compared with efficiencies at pH 6.5, indicating an effective pH-dependent accumulation; the fluorescence intensities of these cells exposed to the dendrimers at pH 6.5 were also 16.45- and 9.27-fold greater, respectively, than those of free doxorubicin. After intravenous administration in mice bearing H22 tumors, doxorubicin-loaded dendrimers exhibited a 1.50-fold greater antitumor activity and presented no obvious systematic toxicity based on histological analysis compared with free drugs. Overall, a simple decoration of carboxymethyl chitosan demonstrated to be a promising way for cationic nanocarriers to achieve pH-sensitive drug release and charge conversion response to tumor microenvironment pH and enhance the antitumor therapy efficiency of anticancer drugs. PMID:27301193

  18. Phase properties of multicomponent superposition states in various amplifiers

    NASA Technical Reports Server (NTRS)

    Lee, Kang-Soo; Kim, M. S.

    1994-01-01

    There have been theoretical studies for generation of optical coherent superposition states. Once the superposition state is generated it is natural to ask if it is possible to amplify it without losing the nonclassical properties of the field state. We consider amplification of the superposition state in various amplifiers such as a sub-Poissonian amplifier, a phase-sensitive amplifier and a classical amplifier. We show the evolution of phase probability distribution functions in the amplifier.

  19. Improvement of Charge Transportation in Si Quantum Dot-Sensitized Solar Cells Using Vanadium Doped TiO2.

    PubMed

    Seo, Hyunwoong; Ichida, Daiki; Hashimoto, Shinji; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu; Nam, Sang-Hun; Boo, Jin-Hyo

    2016-05-01

    The multiple exciton generation characteristics of quantum dots have been expected to enhance the performance of photochemical solar cells. In previous work, we first introduced Si quantum dot for sensitized solar cells. The Si quantum dots were fabricated by multi-hollow discharge plasma chemical vapor deposition, and were characterized optically and morphologically. The Si quantum dot-sensitized solar cells had poor performance due to significant electron loss by charge recombination. Although the large Si particle size resulted in the exposure of a large TiO2 surface area, there was a limit to ho much the particle size could be decreased due to the reduced absorbance of small particles. Therefore, this work focused on decreasing the internal impedance to improve charge transfer. TiO2 was electronically modified by doping with vanadium, which can improve electron transfer in the TiO2 network, and which is stable in the redox electrolyte. Photogenerated electrons can more easily arrive at the conductive electrode due to the decreased internal impedance. The dark photovoltaic properties confirmed the reduction of charge recombination, and the photon-to-current conversion efficiency reflected the improved electron transfer. Impedance analysis confirmed a decrease in internal impedance and an increased electron lifetime. Consequently, these improvements by vanadium doping enhanced the overall performance of Si quantum dot-sensitized solar cells. PMID:27483838

  20. Sensitivity of ion induced charge pulses to the electrical and crystallographic properties of 60° dislocations

    NASA Astrophysics Data System (ADS)

    Breese, M. B. H.; King, P. J. C.; Grime, G. W.

    1994-12-01

    This letter reports evidence that the size of MeV ion induced charge pulses measured from epitaxial Si0.875Ge0.125/Si depends on both the crystallographic and electrical properties of the 60° misfit dislocations present. The results are correlated with both backscattered and transmission ion channeling analysis. With the sample in nonchanneled alignment the measured ion induced charge pulses depend on the number of charge carriers which recombine at the dislocations. With the sample in channeled alignment the rotated (110) and (11¯0) planes around the 60° dislocations affect the local rate of carrier generation and so alter the size of the measured ion induced charge pulses.

  1. Analysis of the Dynamic Sensitivity of Hemisphere-Shaped Electrostatic Sensors' Circular Array for Charged Particle Monitoring.

    PubMed

    Tang, Xin; Chen, Zhong-Sheng; Li, Yue; Hu, Zheng; Yang, Yong-Min

    2016-01-01

    Electrostatic sensor arrays (ESAs) are promising in industrial applications related to charged particle monitoring. Sensitivity is a fundamental and commonly-used sensing characteristic of an ESA. However, the usually used spatial sensitivity, which is called static sensitivity here, is not proper for moving particles or capable of reflecting array signal processing algorithms integrated in an ESA. Besides, reports on ESAs for intermittent particles are scarce yet, especially lacking suitable array signal processing algorithms. To solve the problems, the dynamic sensitivity of ESA is proposed, and a hemisphere-shaped electrostatic sensors' circular array (HSESCA) along with its application in intermittent particle monitoring are taken as an example. In detail, a sensing model of the HSESCA is built. On this basis, its array signals are analyzed; the dynamic sensitivity is thereupon defined by analyzing the processing of the array signals. Besides, a component extraction-based array signal processing algorithm for intermittent particles is proposed, and the corresponding dynamic sensitivity is analyzed quantitatively. Moreover, simulated and experimental results are discussed, which validate the accuracy of the models and the effectiveness of the relevant approaches. The proposed dynamic sensitivity of ESA, as well as the array signal processing algorithm are expected to provide references in modeling, designing and using ESAs. PMID:27589767

  2. Interfacial charge transfer dynamics in TiO2-sensitizer-Ru4POM photocatalytic systems for water oxidation

    NASA Astrophysics Data System (ADS)

    Huang, Zhuangqun; Geletii, Yurii V.; Wu, David; Anfuso, Chantelle L.; Musaev, Djamaladdin G.; Hill, Craig L.; Lian, Tianquan

    2011-10-01

    Efficient solar-driven catalytic water oxidation is one of the main challenges in solar-to-fuel conversion. In this proceeding, we investigate three approaches for constructing electron acceptor -sensitizer - catalysts systems for photocatalytic water oxidation and our current understanding of the relevant fundamental processes involved. We demonstrated that an all-inorganic molecular water oxidation catalyst (WOC), [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2]10- (or Ru4POM), catalyzed a homogenous O2 evolution system with 27% quantum efficiency in homogeneous solution in the presence of sensitizer (Ru(bpy)3) and sacrificial electron donor.1 This suggests the feasibility of a heterogeneous photoelectrochemical system in which the photoanode integrates all three components: electron acceptor, photosensitizer, and WOC. We prepare a photocatalytic electrode based on Ru4POM and a dye-sensitized nanoporous TiO2 film for efficient light-harvesting and charge separation. Ultrafast spectroscopic studies of this triadic nanocomposite indicate efficient charge separation from the excited sensitizer to TiO2 and efficient regeneration of the ground state of the dye. The latter can be attributed to Ru4POM oxidation by the photogenerated dye cation and has a yield of > 80% within 1 ns.

  3. High-sensitivity single NV magnetometry by spin-to-charge state mapping

    NASA Astrophysics Data System (ADS)

    Jaskula, Jean-Christophe; Shields, Brendan; Bauch, Erik; Lukin, Mikhail; Walsworth, Ronald; Trifonov, Alexei

    2015-05-01

    Nitrogen-Vacancy (NV) centers in diamond are atom-like quantum system in a solid state matrix whom its structure allows optical readout of the electronic spin. However, the optimal duration of optical readout is limited by a singlet state lifetime making single shot spin readout out of reach. On the other side, the NV center charge state readout can be extremely efficient (up to 99% fidelity) by using excitation at 594 nm. We will present a new method of spin readout utilizing a spin-depending photoionization process to map the electronic spin state of the NV onto the its charge state. Moreover, pre-selection on the charged state allows to minimize data acquisition time. This scheme improves single NV AC magnetometry by a factor of 5 and will benefit other single NV center experiments as well.

  4. Selective Acylation Enhances Membrane Charge Sensitivity of the Antimicrobial Peptide Mastoparan-X

    PubMed Central

    Etzerodt, Thomas; Henriksen, Jonas R.; Rasmussen, Palle; Clausen, Mads H.; Andresen, Thomas L.

    2011-01-01

    The partitioning of the wasp venom peptide mastoparan-X (MPX) into neutral and negatively charged lipid membranes has been compared with two new synthetic analogs of MPX where the Nα-terminal of MPX was acylated with propanoic acid (PA) and octanoic acid (OA). The acylation caused a considerable change in the membrane partitioning properties of MPX and it was found that the shorter acylation with PA gave improved affinity and selectivity toward negatively charged membranes, whereas OA decreased the selectivity. Based on these findings, we hypothesize that minor differences in the embedding and positioning of the peptide in the membrane caused by either PA or OA acylation play a critical role in the fine-tuning of the effective charge of the peptide and thereby the fine-tuning of the peptide's selectivity between neutral and negatively charged lipid membranes. This finding is unique compared to previous reports where peptide acylation enhanced membrane affinity but also resulted in impaired selectivity. Our result may provide a method of enhancing selectivity of antimicrobial peptides toward bacterial membranes due to their high negative charge—a finding that should be investigated for other, more potent antimicrobial peptides in future studies. PMID:21244836

  5. How well can charge transfer inefficiency be corrected? A parameter sensitivity study for iterative correction

    NASA Astrophysics Data System (ADS)

    Israel, Holger; Massey, Richard; Prod'homme, Thibaut; Cropper, Mark; Cordes, Oliver; Gow, Jason; Kohley, Ralf; Marggraf, Ole; Niemi, Sami; Rhodes, Jason; Short, Alex; Verhoeve, Peter

    2015-10-01

    Radiation damage to space-based charge-coupled device detectors creates defects which result in an increasing charge transfer inefficiency (CTI) that causes spurious image trailing. Most of the trailing can be corrected during post-processing, by modelling the charge trapping and moving electrons back to where they belong. However, such correction is not perfect - and damage is continuing to accumulate in orbit. To aid future development, we quantify the limitations of current approaches, and determine where imperfect knowledge of model parameters most degrades measurements of photometry and morphology. As a concrete application, we simulate 1.5 × 109 `worst-case' galaxy and 1.5 × 108 star images to test the performance of the Euclid visual instrument detectors. There are two separable challenges. If the model used to correct CTI is perfectly the same as that used to add CTI, 99.68 per cent of spurious ellipticity is corrected in our setup. This is because readout noise is not subject to CTI, but gets overcorrected during correction. Secondly, if we assume the first issue to be solved, knowledge of the charge trap density within Δρ/ρ = (0.0272 ± 0.0005) per cent and the characteristic release time of the dominant species to be known within Δτ/τ = (0.0400 ± 0.0004) per cent will be required. This work presents the next level of definition of in-orbit CTI calibration procedures for Euclid.

  6. Photogeneration and transport of charge carriers in hybrid materials of conjugated polymers and dye-sensitized TiO2

    NASA Astrophysics Data System (ADS)

    Däubler, T. K.; Glowacki, I.; Scherf, U.; Ulanski, J.; Hörhold, H.-H.; Neher, D.

    1999-12-01

    Steady state photoconductivity and current-voltage (I-V) experiments are performed on solid films of organic/inorganic composites of dye-sensitized TiO2 in combination with poly(N-vinylcarbazole) (PVK), a ladder-type PPP and a soluble PPV derivative. The I-V characteristics of the composites in the dark are explained by the formation of percolation networks of nanoparticles between the electrodes. Photoaction spectra of the devices prove that the photogeneration of charge carriers is significantly enhanced and spectrally broadened only if electron transfer from the polymer to the dye is possible. Increasing the concentration of the nanoparticles in the hybrid materials changes the spectral shape of the photoresponse. For high TiO2 contents signatures due to the absorption of the Ruthenium dye can be observed. The different electronic properties of anatase/brookite TiO2 and rutile TiO2 have only minor effects on the generation of charge carriers and on the shape of the photoaction spectra. Indeed, photocurrents are more related to the Brunauer—Emmett-Teller surface area of the nanoparticles and thus, to the amount of dye adsorbed. Charge collection efficiencies exceeding 100%, observed for both bias directions, can be explained by photoconductivity gain. It is proposed that recombination is reduced by transport of the oppositely charged carriers in two different phases.

  7. Sensitivity and alternative operating point studies on a high charge CW FEL injector test stand at CEBAF

    SciTech Connect

    Liu, H.; Kehne, D.; Benson, S.

    1995-12-31

    A high charge CW FEL injector test stand is being built at CEBAF based on a 500 kV DC laser gun, a 1500 MHz room-temperature buncher, and a high-gradient ({approx}10 MV/m) CEBAF cryounit containing two 1500 MHz CEBAF SRF cavities. Space-charge-dominated beam dynamics simulations show that this injector should be an excellent high-brightness electron beam source for CW UV FELs if the nominal parameters assigned to each component of the system are experimentally achieved. Extensive sensitivity and alternative operating point studies have been conducted numerically to establish tolerances on the parameters of various injector system components. The consequences of degraded injector performance, due to failure to establish and/or maintain the nominal system design parameters, on the performance of the main accelerator and the FEL itself are discussed.

  8. High dynamic range charge measurements

    DOEpatents

    De Geronimo, Gianluigi

    2012-09-04

    A charge amplifier for use in radiation sensing includes an amplifier, at least one switch, and at least one capacitor. The switch selectively couples the input of the switch to one of at least two voltages. The capacitor is electrically coupled in series between the input of the amplifier and the input of the switch. The capacitor is electrically coupled to the input of the amplifier without a switch coupled therebetween. A method of measuring charge in radiation sensing includes selectively diverting charge from an input of an amplifier to an input of at least one capacitor by selectively coupling an output of the at least one capacitor to one of at least two voltages. The input of the at least one capacitor is operatively coupled to the input of the amplifier without a switch coupled therebetween. The method also includes calculating a total charge based on a sum of the amplified charge and the diverted charge.

  9. KPiX, An Array of Self Triggered Charge Sensitive Cells Generating Digital Time and Amplitude Information

    SciTech Connect

    Freytag, D.; Herbst, R.; Brau, J.; Breidenbach, M.; Frey, R.; Haller, G.; Holbrook, B.; Lander, R.; Nelson, T.; Radeka, V.; Strom, D.; Tripathi, M.; /UC, Davis

    2008-12-11

    The Silicon Detector proposed for the International Linear Collider (ILC) requires electronic read-out that can be tightly coupled to the silicon detectors envisioned for the tracker and the electromagnetic calorimeter. The KPiX is a 1024-channel read-out chip that bump-bonds to the detector and communicates through a few digital signals, power, and detector bias. The KPiX front-end is a low-noise dual-range charge-amplifier with a dynamic range of 17 bit, achieved by autonomous switching of the feedback capacitor. The device takes advantage of the ILC duty cycle of 1 ms trains at 5 Hz rate by lowering the supply current after the data acquisition cycle for an average power consumption of <20 {micro}W/channel. During the 1 ms train, up to four events exceeding a programmable threshold can be stored, the amplitude as a voltage on a capacitor for subsequent digitization, the event time in digital format. The chip can be configured for other than ILC applications.

  10. Low cost instrumentation amplifier

    NASA Technical Reports Server (NTRS)

    Sturman, J. C.

    1974-01-01

    Amplifier can be used for many applications requiring high input impedance and common mode rejection, low drift, and gain accuracy on order of one percent. Performance of inexpensive amplifier approaches that of some commercial instrumentation amplifiers in many specifications.

  11. Co-delivery of erlotinib and doxorubicin by pH-sensitive charge conversion nanocarrier for synergistic therapy.

    PubMed

    He, Yongju; Su, Zhigui; Xue, Lingjing; Xu, Hui; Zhang, Can

    2016-05-10

    Pretreatment of lung cancer cells with epidermal growth factor receptor (EGFR) inhibitor erlotinib has been recently reported that could dramatically synergize their apoptotic response to DNA damage agent doxorubicin (DOX). To translate this synergistic therapy into in vivo anticancer therapy and clinical practice, we designed a novel pH-sensitive charge conversion nanocarrier (M-HHG2C18-L) that contained erlotinib/DOX combination and produced a sequential staggered drug release for synergistic lung cancer therapy. In this study, a synthetic zwitterionic oligopeptide lipid (1,5-dioctadecyl-l-glutamyl2-histidyl-hexahydrobenzoic acid, HHG2C18) was used to construct a pH-sensitive lipid bilayer (HHG2C18-L), which was subsequently applied to coat amino-functionalized mesoporous silica nanoparticles (MSN-NH2). Erlotinib and DOX were separately incorporated into HHG2C18-L and MSN-NH2 respectively to obtain pH-sensitive charge conversion erlotinib/DOX co-delivery nanoparticles (M-HHG2C18-L(E+D)). We confirmed that M-HHG2C18-L(E+D) were able to reverse surface zeta potential from negative to positive at tumor extracellular pH, thus facilitating the targeted cancer cell internalization. Furthermore, as erlotinib was sequestered in the exterior lipid bilayer and the controlled release ability of MSN-NH2, erlotinib released faster than DOX during the cellular transport. Additionally, HHG2C18-L became more positive at tumor intracellular pH and enhanced Coulombic repulsion with MSN-NH2, leading to increased sequential staggered release of erlotinib and DOX. Due to the pretreatment and time-staggered inhibition of EGFR with erlotinib and the enhanced intracellular release of DOX to the nucleus, the maximized synergistic cell killing effect was achieved. Compared to non-sensitive erlotinib/DOX co-delivery nanoparticles (M-SPC-L(E+D)) and simultaneous DRUG coadministration. M-HHG2C18-L(E+D) with sequential staggered drug release and pH-sensitive charge conversional properties

  12. An Acoustic Charge Transport Imager for High Definition Television Applications: Low-Voltage SAW Amplifiers on Multilayer GaAs/ZnO Substrates

    NASA Technical Reports Server (NTRS)

    Hunt, W. D.; Brennan, K. F.; Summers, C. J.; Cameron, Thomas P.

    1996-01-01

    This thesis addresses the acoustoelectric issues concerning the amplification of surface acoustic waves (SAWs) and the reflection of SAWs from slanted reflector gratings on GaAs, with application to a novel acoustic charge transport (ACT) device architecture. First a simple model of the SAWAMP was developed, which was subsequently used to define the epitaxially grown material structure necessary to provide simultaneously high resistance and high electron mobility. In addition, a segmented SAWAMP structure was explored with line widths on the order of an acoustic wavelength. This resulted in the demonstration of SAWAMPS with an order of magnitude less voltage and power requirements than previously reported devices. A two-dimensional model was developed to explain the performance of devices with charge confinement layers less then 0.5 mm, which was experimentally verified. This model was extended to predict a greatly increased gain from the addition of a ZnO overlay. These overlays were experimentally attempted, but no working devices were reported due to process incompatibilities. In addition to the SAWAMP research, the reflection of SAWs from slanted gratings on GaAs was also studied and experimentally determined reflection coefficients for both 45 deg grooves and Al stripes on GaAs have been reported for the first time. The SAWAMp and reflector gratings were combined to investigate the integrated ring oscillator for application to the proposed ACT device and design parameters for this device have been provided.

  13. Solvent dipole modulation of conduction band edge shift and charge recombination in robust dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Hao, Feng; Jiao, Xingjian; Li, Jianbao; Lin, Hong

    2012-12-01

    Molecular modification is certified as a powerful strategy to adjust the energy alignment and electron transfer dynamics of dye-sensitized solar cells (DSCs). Herein, devices are assembled with three robust solvent (3-methoxypropionitrile, N,N-dimethylformamide and γ-butyrolactone) based electrolytes to elucidate the solvent dipole effects at the semiconductor-dye-electrolyte interface. Photovoltaic results demonstrate that open-circuit photovoltages of the devices vary linearly with the dipole moment of the solvents, along with an adverse dependence of the short-circuit photocurrent density under simulated irradiation. Impedance analysis reveals an apparent dipole moment-modulated conduction band edge shift of the nanocrystalline TiO2 electrodes with respect to the redox potential of the electrolyte. Furthermore, the adverse shifts of the short-circuit photocurrent are explained by a dipole dependence of the driving force for electron injection and the interfacial charge recombination, together with a notably changed charge collection efficiency. Therefore, this study draws attention to the feasibility of tuning the electron transfer dynamics and energy alignment in photoelectrochemical devices by judiciously selecting the electrolyte solvents for further efficiency improvement, especially for those alternative organic sensitizers or quantum dots with inadequate electron injection driven forces.

  14. Charge, mass and heat transfer interactions in solid oxide fuel cells operated with different fuel gases-A sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Nagel, Florian P.; Schildhauer, Tilman J.; Biollaz, Serge M. A.; Stucki, Samuel

    The interaction between charge, heat and mass transfer occurring in SOFCs is investigated applying a finite-volume-based SOFC model. The strong interactions are the consequence of the high degree of integration of different processes (chemical/electrochemical reactions, diffusion, heat and mass transfer) within SOFCs. The understanding of these interactions is a key for the future development and application of SOFCs. The investigation was conducted by means of a sensitivity analysis for two different fuel gases, where one gas features a considerable amount of methane inducing steam reforming reactions as additional disturbance factor in the energy and mass balance system of SOFCs. In order to isolate the impact of the varied model parameters and the according changes in the interactions of charge, mass and heat transfer from side effects, the sensitivity analysis was conducted at constant fuel utilization. It was found that the impact of different fuel gases on the operational conditions of SOFCs dominates geometrical and material-induced phenomena. The power output was most affected by the fuel, followed by the values for the activation polarization activation energy that reflects the employed electrode catalysts activity.

  15. Nanocomposite semi-solid redox ionic liquid electrolytes with enhanced charge-transport capabilities for dye-sensitized solar cells.

    PubMed

    Rutkowska, Iwona A; Marszalek, Magdalena; Orlowska, Justyna; Ozimek, Weronika; Zakeeruddin, Shaik M; Kulesza, Pawel J; Grätzel, Michael

    2015-08-10

    The ability of Pt nanostructures to induce the splitting of the II bond in iodine (triiodide) molecules is explored here to enhance electron transfer in the iodine/iodide redox couple. Following the dispersal of Pt nanoparticles at 2 % (weight) level, charge transport was accelerated in triiodide/iodide-containing 1,3-dialkylimidazolium room-temperature ionic liquid. If both Pt nanoparticles and multi-walled carbon nanotubes were introduced into the ionic-liquid-based system, a solid-type (nonfluid) electrolyte was obtained. By using solid-state voltammetric (both sandwich-type and microelectrode-based) methodology, the apparent diffusion coefficients for charge transport increased to approximately 1×10(-6)  cm(2)  s(-1) upon the incorporation of the carbon-nanotube-supported iodine-modified Pt nanostructures. A dye-sensitized solar cell comprising TiO2 covered with a heteroleptic Ru(II) -type sensitizer (dye) and the semisolid triiodide/iodide ionic liquid electrolyte admixed with carbon-nanotube-supported Pt nanostructures yielded somewhat higher power conversion efficiencies (up to 7.9 % under standard reporting conditions) than those of the analogous Pt-free system. PMID:26119519

  16. Improvement in light harvesting in a dye sensitized solar cell based on cascade charge transfer.

    PubMed

    Yang, Lijun; Leung, Wallace Woon-Fong; Wang, Jingchuan

    2013-08-21

    Dye sensitized solar cells (DSSCs) offer the potential of being low-cost, high-efficiency photovoltaic devices. However, the power conversion efficiency is limited as they cannot utilize all photons of the visible solar spectrum. A novel design of a core-shell photoanode is presented herein where a thin shell of infrared dye is deposited over the core of a sensitized TiO2 nanofiber. Specifically, a ruthenium based dye (N719) sensitized TiO2 nanofiber is wrapped by a thin shell of copper phthalocyanine (CuPc). In addition to broadening the absorption spectrum, this core-shell configuration further suppresses the electron-hole recombination process. Instead of adopting the typical Förster resonance energy transfer, upon photons being absorbed by the infrared dye, electrons are transferred efficiently through a cascade process from the CuPc to the N719 dye, the conduction band of TiO2, the FTO electrode and finally the external circuit. Concurrently, photons are also absorbed by the N719 dye with electrons being transferred in the cell. These additive effects result in a high power conversion efficiency of 9.48% for the device. The proposed strategy provides an alternative method for enhancing the performance of DSSCs for low-cost renewable energy in the future. PMID:23831867

  17. Understanding sensitization behavior of lead selenide photoconductive detectors by charge separation model

    SciTech Connect

    Zhao, Lihua E-mail: shi@ou.edu; Qiu, Jijun; Weng, Binbin; Chang, Caleb; Yuan, Zijian; Shi, Zhisheng E-mail: shi@ou.edu

    2014-02-28

    We introduce a charge separation model in this work to explain the mechanism of enhanced photoconductivity of polycrystalline lead salt photoconductors. Our results show that this model could clarify the heuristic fabrication processes of such lead salt detectors that were not well understood and often considered mysterious for nearly a century. The improved lifetime and performance of the device, e.g., responsivity, are attributed to the spatial separation of holes and electrons, hence less possibility of carrier recombination. This model shows that in addition to crystal quality the size of crystallites, the depth of outer conversion layer, and doping concentration could all affect detector performance. The simulation results agree well with experimental results and thus offer a very useful tool for further improvement of lead salt detectors. The model was developed with lead salt family of photoconductors in mind, but may well be applicable to a wider class of semiconducting films.

  18. Transient photocurrent and photovoltage studies on charge transport in dye sensitized solar cells made from the composites of TiO2 nanofibers and nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoxu; Karanjit, Sudeep; Zhang, Lifeng; Fong, Hao; Qiao, Qiquan; Zhu, Zhengtao

    2011-02-01

    Herein, we report the transient photocurrent and photovoltage studies on the charge transport in dye sensitized solar cells (DSSCs) made from the composites of electrospun titanium oxide (TiO2) nanofibers, and conventional TiO2 nanoparticles. The results on charge transport parameters (including the charge recombination lifetime, the electron transport lifetime, and the diffusion length) indicated that the addition of TiO2 nanofibers into composite photoanodes led to substantial improvement on the efficiency of charge collection, suggesting that the composites of nanoparticles and one-dimensional nanostructures are promising materials for the development of DSSCs with high efficiency.

  19. Linear signal-compensated amplifier for reactor power measuring channels

    SciTech Connect

    Khaleeq, M. Tahir; Atique-ur-Rahman,; Ahmed, Eijaz

    2006-07-15

    A linear amplifier with automatic signal compensation has been developed for nuclear channels. The amplifier controls its sensitivity automatically according to the reference input within the desired settings and has automatic signal compensation capability for use in the nuclear channels. The amplifier will be used in the existing safety channel of Pakistan Research Reactor-1, where the system has an independent sensitivity control unit for manual compensation of xenon effect. The new amplifier will improve the safety of the system. The amplifier is tested and the results found are in very good agreement with the designed specifications. This article presents design and construction of the amplifier and test results.

  20. Linear signal-compensated amplifier for reactor power measuring channels

    NASA Astrophysics Data System (ADS)

    Khaleeq, M. Tahir; Atique-ur-Rahman, Ahmed, Eijaz

    2006-07-01

    A linear amplifier with automatic signal compensation has been developed for nuclear channels. The amplifier controls its sensitivity automatically according to the reference input within the desired settings and has automatic signal compensation capability for use in the nuclear channels. The amplifier will be used in the existing safety channel of Pakistan Research Reactor-1, where the system has an independent sensitivity control unit for manual compensation of xenon effect. The new amplifier will improve the safety of the system. The amplifier is tested and the results found are in very good agreement with the designed specifications. This article presents design and construction of the amplifier and test results.

  1. SQUARE WAVE AMPLIFIER

    DOEpatents

    Leavitt, M.A.; Lutz, I.C.

    1958-08-01

    An amplifier circuit is described for amplifying sigmals having an alternating current component superimposed upon a direct current component, without loss of any segnnent of the alternating current component. The general circuit arrangement includes a vibrator, two square wave amplifiers, and recombination means. The amplifier input is connected to the vibrating element of the vibrator and is thereby alternately applied to the input of each square wave amplifier. The detailed circuitry of the recombination means constitutes the novelty of the annplifier and consists of a separate, dual triode amplifier coupled to the output of each square wave amplifier with a recombination connection from the plate of one amplifier section to a grid of one section of the other amplifier. The recombination circuit has provisions for correcting distortion caused by overlapping of the two square wave voltages from the square wave amplifiers.

  2. Holographic modification of TiO2 nanostructure for enhanced charge transport in dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Lee, Jinsoo; Yoon, Junghwan; Jin, Minhea; Lee, Myeongkyu

    2012-08-01

    We show that the photocurrent and energy conversion efficiency of dye-sensitized solar cells can be greatly enhanced with holographic modification to the morphology of TiO2 electrode. The nanoporous electrode coated onto conducting glass was irradiated by three interfering laser beams at 1064 nm incident from the backside of the substrate. This generated two-dimensional periodic pillars of higher density in the electrode, through which the photoexcited electrons could be extracted more effectively. The cells fabricated with modified electrodes exhibited average photocurrent and efficiency of 17.14 mA/cm2 and 9.03%, while 14.91 mA/cm2 and 7.83% were obtained from the reference cells. It was attributed to the enhanced charge transport accompanied by the reduction of internal resistance of the electrode.

  3. Holographic modification of TiO{sub 2} nanostructure for enhanced charge transport in dye-sensitized solar cell

    SciTech Connect

    Lee, Jinsoo; Yoon, Junghwan; Jin, Minhea; Lee, Myeongkyu

    2012-08-15

    We show that the photocurrent and energy conversion efficiency of dye-sensitized solar cells can be greatly enhanced with holographic modification to the morphology of TiO{sub 2} electrode. The nanoporous electrode coated onto conducting glass was irradiated by three interfering laser beams at 1064 nm incident from the backside of the substrate. This generated two-dimensional periodic pillars of higher density in the electrode, through which the photoexcited electrons could be extracted more effectively. The cells fabricated with modified electrodes exhibited average photocurrent and efficiency of 17.14 mA/cm{sup 2} and 9.03%, while 14.91 mA/cm{sup 2} and 7.83% were obtained from the reference cells. It was attributed to the enhanced charge transport accompanied by the reduction of internal resistance of the electrode.

  4. Segmented amplifier configurations for laser amplifier

    DOEpatents

    Hagen, Wilhelm F.

    1979-01-01

    An amplifier system for high power lasers, the system comprising a compact array of segments which (1) preserves high, large signal gain with improved pumping efficiency and (2) allows the total amplifier length to be shortened by as much as one order of magnitude. The system uses a three dimensional array of segments, with the plane of each segment being oriented at substantially the amplifier medium Brewster angle relative to the incident laser beam and with one or more linear arrays of flashlamps positioned between adjacent rows of amplifier segments, with the plane of the linear array of flashlamps being substantially parallel to the beam propagation direction.

  5. Ultrafast charge separation dynamics in opaque, operational dye-sensitized solar cells revealed by femtosecond diffuse reflectance spectroscopy

    PubMed Central

    Ghadiri, Elham; Zakeeruddin, Shaik M.; Hagfeldt, Anders; Grätzel, Michael; Moser, Jacques-E.

    2016-01-01

    Efficient dye-sensitized solar cells are based on highly diffusive mesoscopic layers that render these devices opaque and unsuitable for ultrafast transient absorption spectroscopy measurements in transmission mode. We developed a novel sub-200 femtosecond time-resolved diffuse reflectance spectroscopy scheme combined with potentiostatic control to study various solar cells in fully operational condition. We studied performance optimized devices based on liquid redox electrolytes and opaque TiO2 films, as well as other morphologies, such as TiO2 fibers and nanotubes. Charge injection from the Z907 dye in all TiO2 morphologies was observed to take place in the sub-200 fs time scale. The kinetics of electron-hole back recombination has features in the picosecond to nanosecond time scale. This observation is significantly different from what was reported in the literature where the electron-hole back recombination for transparent films of small particles is generally accepted to occur on a longer time scale of microseconds. The kinetics of the ultrafast electron injection remained unchanged for voltages between +500 mV and –690 mV, where the injection yield eventually drops steeply. The primary charge separation in Y123 organic dye based devices was clearly slower occurring in two picoseconds and no kinetic component on the shorter femtosecond time scale was recorded. PMID:27095505

  6. Arginine side chain interactions and the role of arginine as a gating charge carrier in voltage sensitive ion channels

    PubMed Central

    Armstrong, Craig T.; Mason, Philip E.; Anderson, J. L. Ross; Dempsey, Christopher E.

    2016-01-01

    Gating charges in voltage-sensing domains (VSD) of voltage-sensitive ion channels and enzymes are carried on arginine side chains rather than lysine. This arginine preference may result from the unique hydration properties of the side chain guanidinium group which facilitates its movement through a hydrophobic plug that seals the center of the VSD, as suggested by molecular dynamics simulations. To test for side chain interactions implicit in this model we inspected interactions of the side chains of arginine and lysine with each of the 19 non-glycine amino acids in proteins in the protein data bank. The arginine guanidinium interacts with non-polar aromatic and aliphatic side chains above and below the guanidinium plane while hydrogen bonding with polar side chains is restricted to in-plane positions. In contrast, non-polar side chains interact largely with the aliphatic part of the lysine side chain. The hydration properties of arginine and lysine are strongly reflected in their respective interactions with non-polar and polar side chains as observed in protein structures and in molecular dynamics simulations, and likely underlie the preference for arginine as a mobile charge carrier in VSD. PMID:26899474

  7. Arginine side chain interactions and the role of arginine as a gating charge carrier in voltage sensitive ion channels

    NASA Astrophysics Data System (ADS)

    Armstrong, Craig T.; Mason, Philip E.; Anderson, J. L. Ross; Dempsey, Christopher E.

    2016-02-01

    Gating charges in voltage-sensing domains (VSD) of voltage-sensitive ion channels and enzymes are carried on arginine side chains rather than lysine. This arginine preference may result from the unique hydration properties of the side chain guanidinium group which facilitates its movement through a hydrophobic plug that seals the center of the VSD, as suggested by molecular dynamics simulations. To test for side chain interactions implicit in this model we inspected interactions of the side chains of arginine and lysine with each of the 19 non-glycine amino acids in proteins in the protein data bank. The arginine guanidinium interacts with non-polar aromatic and aliphatic side chains above and below the guanidinium plane while hydrogen bonding with polar side chains is restricted to in-plane positions. In contrast, non-polar side chains interact largely with the aliphatic part of the lysine side chain. The hydration properties of arginine and lysine are strongly reflected in their respective interactions with non-polar and polar side chains as observed in protein structures and in molecular dynamics simulations, and likely underlie the preference for arginine as a mobile charge carrier in VSD.

  8. Ultrafast charge separation dynamics in opaque, operational dye-sensitized solar cells revealed by femtosecond diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Ghadiri, Elham; Zakeeruddin, Shaik M.; Hagfeldt, Anders; Grätzel, Michael; Moser, Jacques-E.

    2016-04-01

    Efficient dye-sensitized solar cells are based on highly diffusive mesoscopic layers that render these devices opaque and unsuitable for ultrafast transient absorption spectroscopy measurements in transmission mode. We developed a novel sub-200 femtosecond time-resolved diffuse reflectance spectroscopy scheme combined with potentiostatic control to study various solar cells in fully operational condition. We studied performance optimized devices based on liquid redox electrolytes and opaque TiO2 films, as well as other morphologies, such as TiO2 fibers and nanotubes. Charge injection from the Z907 dye in all TiO2 morphologies was observed to take place in the sub-200 fs time scale. The kinetics of electron-hole back recombination has features in the picosecond to nanosecond time scale. This observation is significantly different from what was reported in the literature where the electron-hole back recombination for transparent films of small particles is generally accepted to occur on a longer time scale of microseconds. The kinetics of the ultrafast electron injection remained unchanged for voltages between +500 mV and –690 mV, where the injection yield eventually drops steeply. The primary charge separation in Y123 organic dye based devices was clearly slower occurring in two picoseconds and no kinetic component on the shorter femtosecond time scale was recorded.

  9. Ultrafast charge separation dynamics in opaque, operational dye-sensitized solar cells revealed by femtosecond diffuse reflectance spectroscopy.

    PubMed

    Ghadiri, Elham; Zakeeruddin, Shaik M; Hagfeldt, Anders; Grätzel, Michael; Moser, Jacques-E

    2016-01-01

    Efficient dye-sensitized solar cells are based on highly diffusive mesoscopic layers that render these devices opaque and unsuitable for ultrafast transient absorption spectroscopy measurements in transmission mode. We developed a novel sub-200 femtosecond time-resolved diffuse reflectance spectroscopy scheme combined with potentiostatic control to study various solar cells in fully operational condition. We studied performance optimized devices based on liquid redox electrolytes and opaque TiO2 films, as well as other morphologies, such as TiO2 fibers and nanotubes. Charge injection from the Z907 dye in all TiO2 morphologies was observed to take place in the sub-200 fs time scale. The kinetics of electron-hole back recombination has features in the picosecond to nanosecond time scale. This observation is significantly different from what was reported in the literature where the electron-hole back recombination for transparent films of small particles is generally accepted to occur on a longer time scale of microseconds. The kinetics of the ultrafast electron injection remained unchanged for voltages between +500 mV and -690 mV, where the injection yield eventually drops steeply. The primary charge separation in Y123 organic dye based devices was clearly slower occurring in two picoseconds and no kinetic component on the shorter femtosecond time scale was recorded. PMID:27095505

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

    NASA Astrophysics Data System (ADS)

    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).

  11. Sensitivity of nanostructure in charged cubosomes to phase changes triggered by ionic species in solution.

    PubMed

    Liu, Qingtao; Dong, Yao-Da; Hanley, Tracey L; Boyd, Ben J

    2013-11-19

    The phase behavior of dispersions comprising mixed ionic surfactant and phytantriol was precisely controlled by varying the ionic surfactant content in the mixed lipid and the ionic strength in the system. Two important trends in the phase transition of the mixed lipid systems were identified: (1) An increase in the ionic surfactant content increased the curvature of the self-assembled system toward the hydrophobic region, resulting in the phase transition from cubic phase to lamellar phase. (2) An increase in ionic strength decreased repulsion between the headgroups of the ionic surfactant, resulting in a phase transition from lamellar phase to cubic phase. The phase transitions were confirmed using small-angle X-ray scattering and cryo-TEM and were strongly correlated with the visual turbidity of the dispersions. The lipid mixture with anionic surfactant showed high sensitivity to multivalent cations for triggering the phase transition, which may be a potential strategy to develop a detection/treatment system for toxic multivalent metallic cations such as chromium. PMID:24111826

  12. Signal and noise analysis of a-Si:H radiation detector-amplifier system

    SciTech Connect

    Cho, Gyuseong

    1992-03-01

    Hydrogenated amorphous silicon (a-Si:H) has potential advantages in making radiation detectors for many applications because of its deposition capability on a large-area substrate and its high radiation resistance. Position-sensitive radiation detectors can be made out of a 1d strip or a 2-d pixel array of a Si:H pin diodes. In addition, signal processing electronics can be made by thin-film transistors on the same substrate. The calculated radiation signal, based on a simple charge collection model agreed well with results from various wave length light sources and 1 MeV beta particles on sample diodes. The total noise of the detection system was analyzed into (a) shot noise and (b) 1/f noise from a detector diode, and (c) thermal noise and (d) 1/f noise from the frontend TFT of a charge-sensitive preamplifier. the effective noise charge calculated by convoluting these noise power spectra with the transfer function of a CR-RC shaping amplifier showed a good agreement with the direct measurements of noise charge. The derived equations of signal and noise charge can be used to design an a-Si:H pixel detector amplifier system optimally. Signals from a pixel can be readout using switching TFTs, or diodes. Prototype tests of a double-diode readout scheme showed that the storage time and the readout time are limited by the resistances of the reverse-biased pixel diode and the forward biased switching diodes respectively. A prototype charge-sensitive amplifier was made using poly-Si TFTs to test the feasibility of making pixel-level amplifiers which would be required in small-signal detection. The measured overall gain-bandwidth product was {approximately}400 MHz and the noise charge {approximately}1000 electrons at a 1 {mu}sec shaping time. When the amplifier is connected to a pixel detector of capacitance 0.2 pF, it would give a charge-to-voltage gain of {approximately}0.02 mV/electron with a pulse rise time less than 100 nsec and a dynamic range of 48 dB.

  13. Amplified OTDR Systems for Multipoint Corrosion Monitoring

    PubMed Central

    Nascimento, Jehan F.; Silva, Marcionilo J.; Coêlho, Isnaldo J. S.; Cipriano, Eliel; Martins-Filho, Joaquim F.

    2012-01-01

    We present two configurations of an amplified fiber-optic-based corrosion sensor using the optical time domain reflectometry (OTDR) technique as the interrogation method. The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment. The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration. The other amplified monitoring system uses an EDFA in booster configuration and we perform corrosion measurements and evaluations of system sensitivity to amplifier gain variations. Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations. PMID:22737017

  14. Modulation on charge recombination and light harvesting toward high-performance benzothiadiazole-based sensitizers in dye-sensitized solar cells: A theoretical investigation

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Zhao; Zhang, Ji; Li, Hai-Bin; Wu, Yong; Xu, Hong-Liang; Zhang, Min; Geng, Yun; Su, Zhong-Min

    2014-12-01

    Factors associated with short circuit current density (Jsc) and open circuit photovoltage (Voc) of dye sensitized solar cells (DSSCs) have been analyzed through DFT and TDDFT calculations to explore the origin of the significant performance differences with only tiny structure difference (1.24% for 1 and 8.21% for 2) (Advanced Functional Materials 2012, 22, 1291-1302). Our results reveal that the insertion of phenyl ring in 2 enlarges the distance between the dye cation hole and the semiconductor surface and makes the benzothiadiazole (BTDA) unit, which has strong interaction with the electrolyte, far away from the semiconductor, resulting in a decreased charge recombination rate compared with that of 1. However, the insertion of phenyl ring also results in a distortion of the molecular structure, leading to a decreased light harvesting ability. Hence, two dyes (6 and 7) derived from 2 with better conjugation degree, farther position of BTDA unit and longer molecular length have been designed to keep the advantages and overcome the disadvantages of 2 simultaneously. The results demonstrate that we get the desired properties of dyes through reasonable molecular design, and these two dyes could be promising candidates in DSSC field and further improve the performance of the cell.

  15. A label-free and enzyme-free ultra-sensitive transcription factors biosensor using DNA-templated copper nanoparticles as fluorescent indicator and hairpin DNA cascade reaction as signal amplifier.

    PubMed

    Sha, Liang; Zhang, Xiaojun; Wang, Guangfeng

    2016-08-15

    Detection and quantification of specific protein with ultralow concentration play a crucial role in biotechnological applications and biomedical diagnostics. In this paper, a label-free and enzyme-free amplified fluorescent biosensor has been developed for transcription factors detection based on AT-rich double-stranded DNA-templated copper nanoparticles (ds DNA/Cu NPs) and hairpin DNA cascade reaction. This strategy was demonstrated by using nuclear factor-kappa B p50 (NF-κB p50) and specific recognition sequences as a model case. In this assay, a triplex consists of double-stranded DNA containing NF-κB p50 specifically binding sequences and a special design single-stranded DNA (Trigger) which is able to activate the hairpin DNA cascade amplifier (HDCA). In the presence of NF-κB p50, the triplex became unstable since the target bound to the recognition sequences with strong affinity. The selective binding event confirmed that the Trigger was successfully released from the triplex and initiated HDCA to yield the product which could effectively template the formation of fluorescent Cu NPs. The experimental results revealed that the advanced strategy was ultra-sensitive for detecting NF-κB p50 in the concentration range from 0.1 to 1000 pM with a detection limit of 0.096 pM. In addition, the relative standard deviation was 4.08% in 3 repetitive assays of 500 pM NF-κB p50, which indicated that the reproducibility of this strategy was acceptable. Besides desirable sensitivity, the developed biosensor also showed high selectivity, cost-effective, and simplified operations. In addition, the proposed biosensing platform is versatile. By conjugating with various specific recognition units, it could hold considerable potential to sensitive and selective detect various DNA-binding proteins and might find wide applications in biomedical fields. PMID:27045526

  16. Cross-differential amplifier

    NASA Technical Reports Server (NTRS)

    Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

    2008-01-01

    A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

  17. Hybrid matrix amplifier

    DOEpatents

    Martens, J.S.; Hietala, V.M.; Plut, T.A.

    1995-01-03

    The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N[times]M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise. 6 figures.

  18. Cross-differential amplifier

    NASA Technical Reports Server (NTRS)

    Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

    2011-01-01

    A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

  19. Hybrid matrix amplifier

    DOEpatents

    Martens, Jon S.; Hietala, Vincent M.; Plut, Thomas A.

    1995-01-01

    The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N.times.M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise.

  20. Cross-differential amplifier

    NASA Technical Reports Server (NTRS)

    Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

    2013-01-01

    A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

  1. Cross-differential amplifier

    NASA Technical Reports Server (NTRS)

    Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

    2010-01-01

    A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

  2. Progress on diamond amplified photo-cathode

    SciTech Connect

    Wang, E.; Ben-Zvi, I.; Burrill, A.; Kewisch, J.; Chang, X.; Rao, T.; Smedley, J.; Wu, Q.; Muller, E.; Xin, T.

    2011-03-28

    Two years ago, we obtained an emission gain of 40 from the Diamond Amplifier Cathode (DAC) in our test system. In our current systematic study of hydrogenation, the highest gain we registered in emission scanning was 178. We proved that our treatments for improving the diamond amplifiers are reproducible. Upcoming tests planned include testing DAC in a RF cavity. Already, we have designed a system for these tests using our 112 MHz superconducting cavity, wherein we will measure DAC parameters, such as the limit, if any, on emission current density, the bunch charge, and the bunch length. The diamond-amplified photocathode, that promises to support a high average current, low emittance, and a highly stable electron beam with a long lifetime, is under development for an electron source. The diamond, functioning as a secondary emitter amplifies the primary current, with a few KeV energy, that comes from the traditional cathode. Earlier, our group recorded a maximum gain of 40 in the secondary electron emission from a diamond amplifier. In this article, we detail our optimization of the hydrogenation process for a diamond amplifier that resulted in a stable emission gain of 140. We proved that these characteristics are reproducible. We now are designing a system to test the diamond amplifier cathode using an 112MHz SRF gun to measure the limits of the emission current's density, and on the bunch charge and bunch length.

  3. Portable musical instrument amplifier

    DOEpatents

    Christian, David E.

    1990-07-24

    The present invention relates to a musical instrument amplifier which is particularly useful for electric guitars. The amplifier has a rigid body for housing both the electronic system for amplifying and processing signals from the guitar and the system's power supply. An input plug connected to and projecting from the body is electrically coupled to the signal amplifying and processing system. When the plug is inserted into an output jack for an electric guitar, the body is rigidly carried by the guitar, and the guitar is operatively connected to the electrical amplifying and signal processing system without use of a loose interconnection cable. The amplifier is provided with an output jack, into which headphones are plugged to receive amplified signals from the guitar. By eliminating the conventional interconnection cable, the amplifier of the present invention can be used by musicians with increased flexibility and greater freedom of movement.

  4. High voltage distributed amplifier

    NASA Astrophysics Data System (ADS)

    Willems, D.; Bahl, I.; Wirsing, K.

    1991-12-01

    A high-voltage distributed amplifier implemented in GaAs MMIC technology has demonstrated good circuit performance over at least two octave bandwidth. This technique allows for very broadband amplifier operation with good efficiency in satellite, active-aperture radar, and battery-powered systems. Also, by increasing the number of FETs, the amplifier can be designed to match different voltage rails. The circuit does require a small amount of additional chip size over conventional distributed amplifiers but does not require power dividers or additional matching networks. This circuit configuration should find great use in broadband power amplifier design.

  5. Laser amplifier chain

    DOEpatents

    Hackel, R.P.

    1992-10-20

    A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain. 6 figs.

  6. Laser amplifier chain

    DOEpatents

    Hackel, Richard P.

    1992-01-01

    A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain.

  7. Structure and charging of hydrophobic material/water interfaces studied by phase-sensitive sum-frequency vibrational spectroscopy

    PubMed Central

    Tian, C. S.; Shen, Y. R.

    2009-01-01

    We have studied the hydrophobic water/octadecyltrichlorosilane (OTS) interface by using the phase-sensitive sum-frequency vibrational spectroscopy (PS-SFVS), and we obtained detailed structural information of the interface at the molecular level. Excess ions emerging at the interface were detected by changes of the surface vibrational spectrum induced by the surface field created by the excess ions. Both hydronium (H3O+) and hydroxide (OH−) ions were found to adsorb at the interface, and so did other negative ions such as Cl−. By varying the ion concentrations in the bulk water, their adsorption isotherms were measured. It was seen that among the three, OH− has the highest adsorption energy, and H3O+ has the lowest; OH− also has the highest saturation coverage, and Cl− has the lowest. The result shows that even the neat water/OTS interface is not neutral, but charged with OH− ions. The result also explains the surprising observation that the isoelectric point appeared at ∼3.0 when HCl was used to decrease the pH starting from neat water. PMID:19706483

  8. Highly luminescent Sm(III) complexes with intraligand charge-transfer sensitization and the effect of solvent polarity on their luminescent properties.

    PubMed

    Lo, Wai-Sum; Zhang, Junhui; Wong, Wing-Tak; Law, Ga-Lai

    2015-04-20

    Samarium complexes with the highest quantum yields to date have been synthesized, and their luminescence properties were studied in 12 solvents. Sensitization via a nontriplet intraligand charge-transfer pathway was also successfully demonstrated in solution states with good quantum yields. PMID:25835302

  9. Rapid Charge Transport in Dye-Sensitized Solar Cells Made from Vertically Aligned Single-Crystal Rutile TiO2 Nanowires

    SciTech Connect

    Feng, X.; Zhu, K.; Frank, A. J.; Grimes, C. A.; Mallouk, T. E.

    2012-03-12

    A rapid solvothermal approach was used to synthesize aligned 1D single-crystal rutile TiO2 nanowire (NW) arrays on transparent conducting substrates as electrodes for dye-sensitized solar cells. The NW arrays showed a more than 200 times faster charge transport (see picture) and a factor four lower defect state density than conventional rutile nanoparticle films.

  10. Low noise tuned amplifier

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L. (Inventor)

    1984-01-01

    A bandpass amplifier employing a field effect transistor amplifier first stage is described with a resistive load either a.c. or directly coupled to the non-inverting input of an operational amplifier second stage which is loaded in a Wien Bridge configuration. The bandpass amplifier may be operated with a signal injected into the gate terminal of the field effect transistor and the signal output taken from the output terminal of the operational amplifier. The operational amplifier stage appears as an inductive reactance, capacitive reactance and negative resistance at the non-inverting input of the operational amplifier, all of which appear in parallel with the resistive load of the field effect transistor.

  11. The Rotor Electrometer: a New Instrument for Fractional Charge Searches

    NASA Astrophysics Data System (ADS)

    Price, John C.

    A very sensitive electrometer with a charge resolution of less than the charge of one electron is described. The instrument has been developed in hopes that it will allow fractional charge search experiments with very large samples. The method employed is electronic, in contrast to other fractional charge search techniques which involve the measurement of a small force. Pairs of conducting pads are placed around the perimeter of a high speed magnetically levitated rotor, with one member of each pair grounded, and the other capacitively coupled to a low noise JFET amplifier. As the pads move past the stationary sample, which hangs from a quartz glass fiber, a periodic voltage proportional to the charge appears at the amplifier input. Amplifier noise limited resolution of better than one electron per root hertz may be achieved in principle, and in practice a resolution of about one third of an elementary charge has been demonstrated. Photoemission of electrons from the sample is used to calibrate the instrument directly in terms of the electron's charge.

  12. pH-, sugar-, and temperature-sensitive electrochemical switch amplified by enzymatic reaction and controlled by logic gates based on semi-interpenetrating polymer networks.

    PubMed

    Liu, Dan; Liu, Hongyun; Hu, Naifei

    2012-02-01

    Phenylboronic acid (PBA) moieties are grafted onto the backbone of poly(acrylic acid) (PAA), forming the PAA-PBA polyelectrolyte. The semi-interpenetrating polymer network (semi-IPN) films composed of PAA-PBA and poly(N,N-diethylacrylamide) (PDEA) were then synthesized on electrode surface with entrapped horseradish peroxidase (HRP), designated as PDEA-(PAA-PBA)-HRP. The films demonstrated reversible pH-, fructose-, and thermo-responsive on-off behavior toward electroactive probe K(3)Fe(CN)(6) in its cyclic voltammetric (CV) response. This multiswitchable CV behavior of the system could be further employed to control and modulate the electrochemical reduction of H(2)O(2) catalyzed by HRP immobilized in the films with K(3)Fe(CN)(6) as the mediator in solution. The responsive mechanism of the system was also explored and discussed. The pH-sensitive property was attributed to the electrostatic interaction between the PAA component of the films and the probe at different pH; the thermo-responsive behavior originated from the structure change of PDEA hydrogel component of the films with temperature; the fructose-sensitive property was ascribed to the structure change of the films induced by the complexation between the PBA constituent and the sugar. This smart system could be used as a 3-input logic network composed of enabled OR (EnOR) gates in chemical or biomolecular computing by combining the multiresponsive property of the films and the amplification effect of bioelectrocatalysis and demonstrated the potential perspective for fabricating novel multiswitchable electrochemical biosensors and bioelectronic devices. PMID:22239642

  13. Highly selective and sensitive electrochemical biosensor for ATP based on the dual strategy integrating the cofactor-dependent enzymatic ligation reaction with self-cleaving DNAzyme-amplified electrochemical detection.

    PubMed

    Lu, Lu; Si, Jing Cao; Gao, Zhong Feng; Zhang, Yu; Lei, Jing Lei; Luo, Hong Qun; Li, Nian Bing

    2015-01-15

    A dual strategy that combines the adenosine triphosphate (ATP)-dependent enzymatic ligation reaction with self-cleaving DNAzyme-amplified electrochemical detection is employed to construct the biosensor. In this design, the methylene blue-labeled hairpin-structured DNA was self-assembled onto a gold electrode surface to prepare the modified electrode through the interaction of Au-S bond. In the procedure of ATP-dependent ligation reaction, when the specific cofactor ATP was added, the two split oligonucleotide fragments of 8-17 DNAzyme were linked by T4 DNA ligase and then released to hybridize with the labeled hairpin-structured DNA substrate. The linked 8-17 DNAzyme catalyzes the cleavage of the hairpin-structured substrate by the addition of Zn(2+), causing the methylene blue which contains high electrochemical activity to leave the surface of the gold electrode, therefore generating a dramatic decrease of electrochemical signal. The decrease of peak current was readily measured by square wave voltammetry and a relatively low detection limit (0.05 nM) was obtained with a linear response range from 0.1 to 1000 nM. By taking advantage of the highly specific cofactor dependence of the DNA ligation reaction, the proposed ligation-induced DNAzyme cascades demonstrate ultrahigh selectivity toward the target cofactor ATP. A catalytic and molecular beacons strategy is further adopted to amplify the electrochemical signal detection achieved by cycling and regenerating the 8-17 DNAzyme to realize enzymatic multiple turnover, thus one DNAzyme can catalyze the cleavage of several hairpin-structured substrates, which improves the sensitivity of the newly designed electrochemical sensing system. PMID:25048448

  14. Charge-conversional and reduction-sensitive poly(vinyl alcohol) nanogels for enhanced cell uptake and efficient intracellular doxorubicin release.

    PubMed

    Chen, Wei; Achazi, Katharina; Schade, Boris; Haag, Rainer

    2015-05-10

    Charge-conversional and reduction-sensitive polyvinyl alcohol (PVA) nanogels were developed for efficient cancer treatment by enhanced cell uptake and intracellular triggered doxorubicin (DOX) release. These PVA nanogels were prepared in a straightforward manner by inverse nanoprecipitation via "click" reaction with an average diameter of 118nm. The introduction of COOH into the PVA nanogels efficiently improved the DOX encapsulation due to the electrostatic interaction. The in vitro release result showed that the decrease of electrostatic interaction between COOH and DOX under a mimicking endosomal pH, in combination with the cleavage of the intervening disulfide bonds in response to a high glutathione (GSH) concentration led to a fast and complete release of DOX. Furthermore, confocal laser scanning microscopy (CLSM) revealed that the ultra pH-sensitive terminal groups allowed nanogels to reverse their surface charge from negative to positive under a tumor extracellular pH (6.5-6.8) which facilitated cell internalization. MTT assays and real time cell analysis (RTCA) showed that these DOX-loaded charge-conversional and reducible PVA nanogels had much better cell toxicity than DOX-loaded non-charge-conversional or reduction-insensitive PVA nanogels following 48h of incubation. These novel charge-conversional and stimuli-responsive PVA nanogels are highly promising for targeted intracellular anticancer drug release. PMID:25445693

  15. Effect of Molecular Coupling on Ultrafast Electron-Transfer and Charge-Recombination Dynamics in a Wide-Gap ZnS Nanoaggregate Sensitized by Triphenyl Methane Dyes.

    PubMed

    Debnath, Tushar; Maity, Partha; Dana, Jayanta; Ghosh, Hirendra N

    2016-03-01

    Wide-band-gap ZnS nanocrystals (NCs) were synthesized, and after sensitizing the NCs with series of triphenyl methane (TPM) dyes, ultrafast charge-transfer dynamics was demonstrated. HRTEM images of ZnS NCs show the formation of aggregate crystals with a flower-like structure. Exciton absorption and lumimescence, due to quantum confinement of the ZnS NCs, appear at approximately 310 and 340 nm, respectively. Interestingly, all the TPM dyes (pyrogallol red, bromopyrogallol red, and aurin tricarboxylic acid) form charge-transfer complexes with the ZnS NCs, with the appearance of a red-shifted band. Electron injection from the photoexcited TPM dyes into the conduction band of the ZnS NCs is shown to be a thermodynamically viable process, as confirmed by steady-state and time-resolved emission studies. To unravel charge-transfer (both electron injection and charge recombination) dynamics and the effect of molecular coupling, femtosecond transient absorption studies were carried out in TPM-sensitized ZnS NCs. The electron-injection dynamics is pulse-width-limited in all the ZnS/TPM dye systems, however, the back electron transfer differs, depending on the molecular coupling of the sensitizers (TPM dyes). The detailed mechanisms for the above-mentioned processes are discussed. PMID:26548569

  16. Wireless Josephson amplifier

    SciTech Connect

    Narla, A.; Sliwa, K. M.; Hatridge, M.; Shankar, S.; Frunzio, L.; Schoelkopf, R. J.; Devoret, M. H.

    2014-06-09

    Josephson junction parametric amplifiers are playing a crucial role in the readout chain in superconducting quantum information experiments. However, their integration with current 3D cavity implementations poses the problem of transitioning between waveguide, coax cables, and planar circuits. Moreover, Josephson amplifiers require auxiliary microwave components, like directional couplers and/or hybrids, that are sources of spurious losses and impedance mismatches that limit measurement efficiency and amplifier tunability. We have developed a wireless architecture for these parametric amplifiers that eliminates superfluous microwave components and interconnects. This greatly simplifies their assembly and integration into experiments. We present an experimental realization of such a device operating in the 9–11 GHz band with about 100 MHz of amplitude gain-bandwidth product, on par with devices mounted in conventional sample holders. The simpler impedance environment presented to the amplifier also results in increased amplifier tunability.

  17. Diode amplifier of modulated optical beam power

    SciTech Connect

    D'yachkov, N V; Bogatov, A P; Gushchik, T I; Drakin, A E

    2014-11-30

    Analytical relations are obtained between characteristics of modulated light at the output and input of an optical diode power amplifier operating in the highly saturated gain regime. It is shown that a diode amplifier may act as an amplitude-to-phase modulation converter with a rather large bandwidth (∼10 GHz). The low sensitivity of the output power of the amplifier to the input beam power and its high energy efficiency allow it to be used as a building block of a high-power multielement laser system with coherent summation of a large number of optical beams. (lasers)

  18. Compact laser amplifier system

    DOEpatents

    Carr, R.B.

    1974-02-26

    A compact laser amplifier system is described in which a plurality of face-pumped annular disks, aligned along a common axis, independently radially amplify a stimulating light pulse. Partially reflective or lasing means, coaxially positioned at the center of each annualar disk, radially deflects a stimulating light directed down the common axis uniformly into each disk for amplification, such that the light is amplified by the disks in a parallel manner. Circumferential reflecting means coaxially disposed around each disk directs amplified light emission, either toward a common point or in a common direction. (Official Gazette)

  19. Strong sensitivity of x-ray emission lines following charge exchange between highly charged ions and H (1 s ) in weakly screened media

    NASA Astrophysics Data System (ADS)

    Cariatore, N. D.; Otranto, S.

    2015-11-01

    We use the classical trajectory Monte Carlo method to analyze charge exchange processes between fully stripped projectiles with H (1 s ) in a screened environment at impact energies in the range 18 eV/amu to 10 keV/amu. For Fe+26 projectiles, (n ,l )-state selective charge exchange and line emission cross sections are presented for Debye screening lengths from 15 a.u. up to the unscreened case limit. At low-impact energies, a strong dependence of the hardness ratio on the Debye screening length is found. We show that such strong dependence also evidences itself for Ne+10,P+15,Ar+18, and Kr+36 projectiles. Clear indications of this dependence are noticeable in the photonic spectra even for large screening lengths (˜100 a.u.).

  20. Enhanced Photoelectrochemical Immunosensing Platform Based on CdSeTe@CdS:Mn Core-Shell Quantum Dots-Sensitized TiO2 Amplified by CuS Nanocrystals Conjugated Signal Antibodies.

    PubMed

    Fan, Gao-Chao; Zhu, Hua; Du, Dan; Zhang, Jian-Rong; Zhu, Jun-Jie; Lin, Yuehe

    2016-03-15

    A new, ultrasensitive photoelectrochemical immunosensing platform was established on the basis of CdSeTe@CdS:Mn core-shell quantum dots-sensitized TiO2 coupled with signal amplification of CuS nanocrystals conjugated signal antibodies. In this proposal, carcinoembryonic antigen (CEA, Ag) was selected as an example of target analyte to show the analytical performances of the platform. Specifically, TiO2-modified electrode was first assembled with CdSeTe alloyed quantum dots (AQDs) via electrostatic adsorption assisted by oppositely charged polyelectrolyte, and then further deposited with CdS:Mn shells on the surface of CdSeTe AQDs via successive ionic layer adsorption and reaction strategy, forming TiO2/CdSeTe@CdS:Mn sensitization structure, which was used as photoelectrochemical matrix to immobilize capture CEA antibodies (Ab1); signal CEA antibodies (Ab2) were labeled with CuS nanocrystals (NCs) to form Ab2-CuS conjugates, which were employed as signal amplification elements when specific immunoreaction occurred. The ultrahigh sensitivity of this immunoassay resulted from the following two aspects. Before detection of target Ag, the TiO2/CdSeTe@CdS:Mn sensitization structure could adequately harvest the exciting light with different bands, evidently expedite the electron transfer, and effectively depress the charge recombination, resulting in noticeably increased photocurrent. When target Ag existed, the Ab2-CuS conjugates could dramatically decrease the photocurrent due to competitive absorption of exciting light and consumption of electron donor for CuS NCs coupled with steric hindrance of Ab2 molecules. The fabricated photoelectrochemical immunosensor showed a low limit of detection of 0.16 pg/mL and a wide linear range from 0.5 pg/mL to 100 ng/mL for CEA detection, and it also exhibited good specificity, reproducibility, and stability. PMID:26910366

  1. Simulation of intramolecular hydrogen bond dynamics in manzamine A as a sensitive test for charge distribution quality.

    PubMed

    Shulga, Dmitry A; Osolodkin, Dmitry I; Palyulin, Vladimir A; Zefirov, Nikolay S

    2012-03-01

    Subtle balance of inter- and intramolecular hydrogen bond strength in aqueous solutions often governs the structure and dynamics of molecular species used as potential drugs and in supramolecular applications. In silico molecular dynamics study of water solution of manzamine A has been performed with different atomic charges in order to investigate the influence of charge distribution choice on predicting qualitative and quantitative features of the simulated systems. Various well known charge schemes (MK-ESP, RESP, Mulliken, AMI-BCC, Gasteiger-Hückel, Gasteiger-Marsili, MMFF94, and Dynamic Electronegativity Relaxation - DENR) led to qualitatively different pictures of dynamic behavior of the intramolecular hydrogen bond. The reported calculation framework represents a relatively rare case where differences in charge distributions lead to noticeable differences in simulated properties, thus providing a useful test case for force field and charge distribution development, provided high quality experiments are conducted to use as references. PMID:22545399

  2. DIAMOND AMPLIFIER FOR PHOTOCATHODES.

    SciTech Connect

    RAO,T.; BEN-ZVI,I.; BURRILL,A.; CHANG,X.; HULBERT,S.; JOHNSON,P.D.; KEWISCH,J.

    2004-06-21

    We report a new approach to the generation of high-current, high-brightness electron beams. Primary electrons are produced by a photocathode (or other means) and are accelerated to a few thousand electron-volts, then strike a specially prepared diamond window. The large Secondary Electron Yield (SEY) provides a multiplication of the number of electrons by about two orders of magnitude. The secondary electrons drift through the diamond under an electric field and emerge into the accelerating proper of the ''gun'' through a Negative Electron Affinity surface of the diamond. The advantages of the new approach include the following: (1) Reduction of the number of primary electrons by the large SEY, i.e. a very low laser power in a photocathode producing the primaries. (2) Low thermal emittance due to the NEA surface and the rapid thermalization of the electrons. (3) Protection of the cathode from possible contamination from the gun, allowing the use of large quantum efficiency but sensitive cathodes. (4) Protection of the gun from possible contamination by the cathode, allowing the use of superconducting gun cavities. (5) Production of high average currents, up to ampere class. (6) Encapsulated design, making the ''load-lock'' systems unnecessary. This paper presents the criteria that need to be taken into account in designing the amplifier.

  3. Integrating amplifiers using cooled JFETs

    NASA Astrophysics Data System (ADS)

    Low, F. J.

    1984-05-01

    It is shown how a simple integrating amplifier based on commercially available JFET and MOSFET switches can be used to measure photocurrents from detectors with noise levels as low as 1.6 x 10 to the -18th A/root Hz (10 electrons/sec). A figure shows the basic circuit, along with the waveform at the output. The readout is completely nondestructive; the reset noise does not contribute since sampling of the accumulated charge occurs between resets which are required only when the stored charge has reached a very high level. The storage capacity ranges from 10 to the 6th to 10 to the 9th electrons, depending on detector parameters and linearity requirements. Data taken with an Si:Sb detector operated at 24 microns are presented. The responsivity agrees well with the value obtained by Young et al. (1981) in the transimpedance amplifier circuit. The data are seen as indicating that extremely low values of NEP can be obtained for integration times of 1 sec and that longer integrations continue to improve the SNR at a rate faster than the square root of time when background noise is not present.

  4. Dye laser amplifier

    DOEpatents

    Moses, Edward I.

    1992-01-01

    An improved dye laser amplifier is disclosed. The efficiency of the dye lr amplifier is increased significantly by increasing the power of a dye beam as it passes from an input window to an output window within the dye chamber, while maintaining the intensity of the dye beam constant.

  5. Dye laser amplifier

    DOEpatents

    Moses, E.I.

    1992-12-01

    An improved dye laser amplifier is disclosed. The efficiency of the dye laser amplifier is increased significantly by increasing the power of a dye beam as it passes from an input window to an output window within the dye chamber, while maintaining the intensity of the dye beam constant. 3 figs.

  6. DIRECT COUPLED AMPLIFIER

    DOEpatents

    Dandl, R.A.

    1961-09-19

    A transistor amplifier is designed for vyery small currents below 10/sup -8/ amperes. The filrst and second amplifier stages use unusual selected transistors in which the current amplification increases markedly for values of base current below 10/sup -6/ amperes.

  7. Amplifier improvement circuit

    NASA Technical Reports Server (NTRS)

    Sturman, J.

    1968-01-01

    Stable input stage was designed for the use with a integrated circuit operational amplifier to provide improved performance as an instrumentation-type amplifier. The circuit provides high input impedance, stable gain, good common mode rejection, very low drift, and low output impedance.

  8. Linearly polarized fiber amplifier

    DOEpatents

    Kliner, Dahv A.; Koplow, Jeffery P.

    2004-11-30

    Optically pumped rare-earth-doped polarizing fibers exhibit significantly higher gain for one linear polarization state than for the orthogonal state. Such a fiber can be used to construct a single-polarization fiber laser, amplifier, or amplified-spontaneous-emission (ASE) source without the need for additional optical components to obtain stable, linearly polarized operation.

  9. Sensitivity of combustion and ignition characteristics of the solid-fuel charge of the microelectromechanical system of a microthruster to macrokinetic and design parameters

    NASA Astrophysics Data System (ADS)

    Futko, S. I.; Ermolaeva, E. M.; Dobrego, K. V.; Bondarenko, V. P.; Dolgii, L. N.

    2012-07-01

    We have developed a sensitivity analysis permitting effective estimation of the change in the impulse responses of a microthrusters and in the ignition characteristics of the solid-fuel charge caused by the variation of the basic macrokinetic parameters of the mixed fuel and the design parameters of the microthruster's combustion chamber. On the basis of the proposed sensitivity analysis, we have estimated the spread of both the propulsive force and impulse and the induction period and self-ignition temperature depending on the macrokinetic parameters of combustion (pre-exponential factor, activation energy, density, and heat content) of the solid-fuel charge of the microthruster. The obtained results can be used for rapid and effective estimation of the spread of goal functions to provide stable physicochemical characteristics and impulse responses of solid-fuel mixtures in making and using microthrusters.

  10. DISTRIBUTED AMPLIFIER INCORPORATING FEEDBACK

    DOEpatents

    Bell, P.R. Jr.

    1958-10-21

    An improved distributed amplifier system employing feedback for stabilization is presented. In accordance with the disclosed invention, a signal to be amplified is applled to one end of a suitable terminated grid transmission line. At intervals along the transmission line, the signal is fed to stable, resistance-capacitance coupled amplifiers incorporating feedback loops therein. The output current from each amplifier is passed through an additional tube to minimize the electrostatic capacitance between the tube elements of the last stage of the amplifier, and fed to appropriate points on an output transmission line, similar to the grid line, but terminated at the opposite (input) end. The output taken from the unterminated end of the plate transmission line is proportional to the input voltage impressed upon the grid line.

  11. Versatile composite amplifier configuration

    NASA Astrophysics Data System (ADS)

    Gift, Stephan J. G.; Maundy, Brent

    2015-06-01

    This paper describes a versatile composite amplifier in which a current feedback amplifier (CFA) drives an operational amplifier (OPA). In the conventional OPA-CFA composite amplifier, an OPA drives a CFA resulting in a composite structure that combines the DC input stability of the OPA and the high speed capability of the CFA. The proposed composite configuration combines different features of the CFA and OPA, specifically the constant bandwidth property of the CFA and the high power and high current output capacity of the OPA. The new circuit is easily implemented in the standard inverting and non-inverting configurations using commercially available devices, and the accuracy and constant bandwidth features were experimentally verified. Local feedback around the associated CFA ensures that the proposed composite amplifier possesses a higher level of bandwidth constancy than a single CFA.

  12. Optimization of a cold preamplifier for infrared detectors of the highest sensitivity

    NASA Astrophysics Data System (ADS)

    Frick, D.

    1985-07-01

    The cold preamplifier needed for the infrared camera in the German Infrared Laboratory (GIRL) is theoretically examined. An expression for the theoretically attainable lower noise level and for the SNR is derived which demonstrates the dependence of the SNR on the shunt capacity. A transimpedance amplifier (TIA) with GaAs FET prestep whose operation has some advantages over that of a TIA with operational amplifier is studied. This TIA is suitable for signal processing in IR detectors of highest sensitivity. First test results for a charge-dependent amplifier are also reported.

  13. Ultrafast polarisation spectroscopy of photoinduced charges in a conjugated polymer

    SciTech Connect

    Bakulin, A A; Loosdrecht, P van; Pshenichnikov, M S; Parashchuk, D Yu

    2009-07-31

    Tunable optical parametric generators and amplifiers (OPA), proposed and developed by Akhmanov and his colleagues, have become the working horses in exploration of dynamical processes in physics, chemistry, and biology. In this paper, we demonstrate the possibility of using ultrafast polarisation-sensitive two-colour spectroscopy, performed with a set of two OPAs, to study charge photogeneration and transport in conjugated polymers and their donor-acceptor blends. (special issue devoted to the 80th birthday of S.A. Akhmanov)

  14. Tuning Broadband Microwave Amplifiers

    SciTech Connect

    Alaniz, Gabriel

    2003-09-05

    The PEP-II/DA {Phi} NE/ALS longitudinal feedback systems are complex wide bandwidth systems requiring analog, digital and microwave circuits. The solid-state amplifier is one of the components in the microwave circuit that is required to suppress the coupled bunch instabilities that exist in the PEP-II accelerator. The suppression is achieved by using an antenna as a kicker structure that provides an electric field in order to increase or decrease the energy of particles passing through the structure. The amplifier is made up of sixteen 30 to 35W microstrip GaAs FET modules that are combined to obtain 500W over a bandwidth of 850MHz to 1850MHz. The amplifier malfunctioned causing a reduction in the functionality and power output of the individual GaAs FET modules. The amplifier must be repaired. After repair, the amplifier must be tuned to optimize the gain while maintaining proper power output. The amplifier is tuned using microstrip circuit techniques. A variety of microstrip methods are used to obtain the proper line impedance. The result is a working amplifier that operates efficiently.

  15. Universal signal conditioning amplifier

    NASA Technical Reports Server (NTRS)

    Medelius, Pedro J.; Hallberg, Carl; Cecil, Jim

    1994-01-01

    A state-of-the-art instrumentation amplifier capable of being used with most types of transducers has been developed at the Kennedy Space Center. This Universal Signal Conditioning Amplifier (USCA) can eliminate costly measurement setup item and troubleshooting, improve system reliability and provide more accurate data than conventional amplifiers. The USCA can configure itself for maximum resolution and accuracy based on information read from a RAM chip attached to each transducer. Excitation voltages or current are also automatically configured. The amplifier uses both analog and digital state-of-the-art technology with analog-to-digital conversion performed in the early stages in order to minimize errors introduced by offset and gain drifts in the analog components. A dynamic temperature compensation scheme has been designed to achieve and maintain 12-bit accuracy of the amplifier from 0 to 70 C. The digital signal processing section allows the implementation of digital filters up to 511th order. The amplifier can also perform real-time linearizations up to fourth order while processing data at a rate of 23.438 kS/s. Both digital and analog outputs are available from the amplifier.

  16. Multipass optical parametric amplifier

    SciTech Connect

    Jeys, T.H.

    1996-08-01

    A compact, low-threshold, multipass optical parametric amplifier has been developed for the conversion of short-pulse (360-ps) 1064-nm Nd:YAG laser radiation into eye-safe 1572-nm radiation for laser ranging and radar applications. The amplifier had a threshold pump power of as low as 45{mu}J, and at three to four times this threshold pump power the amplifier converted 30{percent} of the input 1064-nm radiation into 1572-nm output radiation. {copyright} {ital 1996 Optical Society of America.}

  17. Determination of {sup 16}O and {sup 18}O sensitivity factors and charge-exchange processes in low-energy ion scattering

    SciTech Connect

    Tellez, H.; Chater, R. J.; Fearn, S.; Symianakis, E.; Kilner, J. A.; Brongersma, H. H.

    2012-10-08

    Quantitative analysis in low-energy ion scattering (LEIS) requires an understanding of the charge-exchange processes to estimate the elemental sensitivity factors. In this work, the neutralization of He{sup +} scattered by {sup 18}O-exchanged silica at energies between 0.6 and 7 keV was studied. The process is dominated by Auger neutralization for E{sub i} < 0.8 keV. An additional mechanism starts above the reionization threshold. This collision-induced neutralization becomes the dominant mechanism for E{sub i} > 2 keV. The ion fractions P{sup +} were determined for Si and O using the characteristic velocity method to quantify the surface density. The {sup 18}O/{sup 16}O sensitivity ratio indicates an 18% higher sensitivity for the heavier O isotope.

  18. Amplify Interest in STS.

    ERIC Educational Resources Information Center

    Chiappetta, Eugene L; Mays, John D.

    1992-01-01

    Presents activities in which students construct simple crystal radio sets and amplifiers out of diodes, transistors, and integrated circuits. Provides conceptual background, materials needed, instructions, diagrams, and classroom applications. (MDH)

  19. Fully relayed regenerative amplifier

    DOEpatents

    Glass, Alexander J.

    1981-01-01

    A regenerative laser apparatus and method using the optical relay concept to maintain high fill factors, to suppress diffraction effects, and to minimize phase distortions in a regenerative amplifier.

  20. Sensitive detection of miRNA by using hybridization chain reaction coupled with positively charged gold nanoparticles.

    PubMed

    Miao, Xiangmin; Ning, Xue; Li, Zongbing; Cheng, Zhiyuan

    2016-01-01

    Positively charged gold nanoparticles (+)AuNPs can adsorb onto the negatively charged surface of single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA). Herein, long-range dsDNA polymers could form based on the hybridization chain reaction (HCR) of two hairpin probes (H1 and H2) by using miRNA-21 as an initiator. (+)AuNPs could adsorb onto the negatively charged surface of such long-range dsDNA polymers based on the electrostatic adsorption, which directly resulted in the precipitation of (+)AuNPs and the decrease of (+)AuNPs absorption spectra. Under optimal conditions, miRNA-21 detection could be realized in the range of 20 pM-10 nM with a detection limit of 6.8 pM. In addition, (+)AuNPs used here are much more stable than commonly used negatively charged gold nanoparticles ((-)AuNPs) in mixed solution that contained salt, protein or other metal ions. Importantly, the assay could realize the detection of miRNA in human serum samples. PMID:27576601

  1. Sensitive detection of miRNA by using hybridization chain reaction coupled with positively charged gold nanoparticles

    PubMed Central

    Miao, Xiangmin; Ning, Xue; Li, Zongbing; Cheng, Zhiyuan

    2016-01-01

    Positively charged gold nanoparticles (+)AuNPs can adsorb onto the negatively charged surface of single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA). Herein, long-range dsDNA polymers could form based on the hybridization chain reaction (HCR) of two hairpin probes (H1 and H2) by using miRNA-21 as an initiator. (+)AuNPs could adsorb onto the negatively charged surface of such long-range dsDNA polymers based on the electrostatic adsorption, which directly resulted in the precipitation of (+)AuNPs and the decrease of (+)AuNPs absorption spectra. Under optimal conditions, miRNA-21 detection could be realized in the range of 20 pM-10 nM with a detection limit of 6.8 pM. In addition, (+)AuNPs used here are much more stable than commonly used negatively charged gold nanoparticles ((−)AuNPs) in mixed solution that contained salt, protein or other metal ions. Importantly, the assay could realize the detection of miRNA in human serum samples. PMID:27576601

  2. Ab Initio Simulation of Charge Transfer at the Semiconductor Quantum Dot/TiO 2 Interface in Quantum Dot-Sensitized Solar Cells

    DOE PAGESBeta

    Xin, Xukai; Li, Bo; Jung, Jaehan; Yoon, Young Jun; Biswas, Rana; Lin, Zhiqun

    2014-07-24

    Quantum dot-sensitized solar cells (QDSSCs) have emerged as a promising solar architecture for next-generation solar cells. The QDSSCs exhibit a remarkably fast electron transfer from the quantum dot (QD) donor to the TiO2 acceptor with size quantization properties of QDs that allows for the modulation of band energies to control photoresponse and photoconversion efficiency of solar cells. In order to understand the mechanisms that underpin this rapid charge transfer, the electronic properties of CdSe and PbSe QDs with different sizes on the TiO2 substrate are simulated using a rigorous ab initio density functional method. Our method capitalizes on localized orbitalmore » basis set, which is computationally less intensive. Quite intriguingly, a remarkable set of electron bridging states between QDs and TiO2 occurring via the strong bonding between the conduction bands of QDs and TiO2 is revealed. Such bridging states account for the fast adiabatic charge transfer from the QD donor to the TiO2 acceptor, and may be a general feature for strongly coupled donor/acceptor systems. All the QDs/TiO2 systems exhibit type II band alignments, with conduction band offsets that increase with the decrease in QD size. This facilitates the charge transfer from QDs donors to TiO2 acceptors and explains the dependence of the increased charge transfer rate with the decreased QD size.« less

  3. Charge transport in zirconium doped anatase nanowires dye-sensitized solar cells: Trade-off between lattice strain and photovoltaic parameters

    SciTech Connect

    Archana, P. S.; Gupta, Arunava; Yusoff, Mashitah M.; Jose, Rajan

    2014-10-13

    Zirconium (Zr) is doped up to 5 at. % in anatase TiO{sub 2} nanowires by electrospinning and used as working electrode in dye-sensitized solar cells. Variations observed in the photovoltaic parameters were correlated by electrochemical impedance spectroscopy, open circuit voltage decay, and X-ray diffraction measurements. Results show that homovalent substitution of Zr in TiO{sub 2} increased the chemical capacitance and electron diffusion coefficient which in turn decreased charge transport resistance and charge transit time. However, lattice strain due to size mismatch between the Zr{sup 4+} and Ti{sup 4+} ions decreased open circuit voltage and fill factor thereby setting a trade-off between doping concentration and photovoltaic properties.

  4. Interfacial charge recombination via the triplet state? Mimicry of photoprotection in the photosynthetic process with a dye-sensitized TiO 2 solar cell reaction

    NASA Astrophysics Data System (ADS)

    Weng, Yu-Xiang; Li, Long; Liu, Yin; Wang, Li; Yang, Guo-Zhen; Sheng, Jian-Qun

    2002-04-01

    Evidence for the photoinduced charge recombination to the excited-triplet state has been observed in chemical solar cell reaction consisting of dye-sensitized TiO 2 colloidal ethanol solution, which mimicks the photoprotection function in the photosynthetic units. The dye is all -trans-retinoic acid, a structural analog of β-carotenoid. Two channels of charge recombination, i.e., through triplet and ground states were observed by nano-second flash photolysis. The possibility of applying the function of photoprotection to the synthetic solar cell is discussed, which provides a potential entry of molecular engineering of the dye to improve the long term stability of the synthetic solar cell.

  5. Visualizing interfacial charge transfer in Ru-dye sensitized TiO{sub 2} nanoparticles using x-ray transient absorption spectroscopy.

    SciTech Connect

    Zhang, X.; Smolentsev, G.; Guo, J.; Attenkofer, K.; Kurtz, C.; Jennings, G.; Lockard, J. V.; Stickrath, A. B.; Chen, L. X.

    2011-03-01

    A molecular level understanding of the structural reorganization accompanying interfacial electron transfer is important for rational design of solar cells. Here we have applied XTA (X-ray transient absorption) spectroscopy to study transient structures in a heterogeneous interfacial system mimicking the charge separation process in dye-sensitized solar cell (DSSC) with Ru(dcbpy){sub 2}(NCS){sub 2} (RuN3) dye adsorbed to TiO{sub 2} nanoparticle surfaces. The results show that the average Ru-NCS bond length reduces by 0.06 {angstrom}, whereas the average Ru?N(dcbpy) bond length remains nearly unchanged after the electron injection. The differences in bond-order change and steric hindrance between two types of ligands are attributed to their structural response in the charge separation. This study extends the application of XTA into optically opaque hybrid interfacial systems relevant to the solar energy conversion.

  6. LOW-LEVEL DIRECT CURRENT AMPLIFIER

    DOEpatents

    Kerns, Q.A.

    1959-05-01

    A d-c amplifier is described. Modulation is provided between a d-c signal and an alternating current to give an output signal proportional to the d- c signal. The circuit has high sensitivity and accuracy. (T.R.H.)

  7. Solid state radiographic image amplifiers, part C

    NASA Technical Reports Server (NTRS)

    Szepesi, Z.

    1971-01-01

    The contrast sensitivity of the radiographic amplifiers, both the storage type and nonstorage type, their absolute sensitivity, and the reproducibility of fabrication were investigated. The required 2-2T quality level was reached with the radiographic storage screen. The sensitivity threshold was 100 to 200 mR with 45 to 100 kV filtered X-rays. The quality level of the radiographic amplifier screen (without storage) was 4-4T; for a 6 mm (0.25 in.) thick aluminum specimen, a 1 mm (0.040 in.) diameter hole in a 0.25 mm (0.010 in.) thick penetrameter was detected. Its sensitivity threshold was 2 to 6 mR/min. The developed radiographic screens are applicable for uses in nondestructive testing.

  8. Laser amplifier and method

    DOEpatents

    Backus, S.; Kapteyn, H.C.; Murnane, M.M.

    1997-07-01

    Laser amplifiers and methods for amplifying a laser beam are disclosed. A representative embodiment of the amplifier comprises first and second curved mirrors, a gain medium, a third mirror, and a mask. The gain medium is situated between the first and second curved mirrors at the focal point of each curved mirror. The first curved mirror directs and focuses a laser beam to pass through the gain medium to the second curved mirror which reflects and recollimates the laser beam. The gain medium amplifies and shapes the laser beam as the laser beam passes therethrough. The third mirror reflects the laser beam, reflected from the second curved mirror, so that the laser beam bypasses the gain medium and return to the first curved mirror, thereby completing a cycle of a ring traversed by the laser beam. The mask defines at least one beam-clipping aperture through which the laser beam passes during a cycle. The gain medium is pumped, preferably using a suitable pumping laser. The laser amplifier can be used to increase the energy of continuous-wave or, especially, pulsed laser beams including pulses of femtosecond duration and relatively high pulse rate. 7 figs.

  9. Laser amplifier and method

    DOEpatents

    Backus, Sterling; Kapteyn, Henry C.; Murnane, Margaret M.

    1997-01-01

    Laser amplifiers and methods for amplifying a laser beam are disclosed. A representative embodiment of the amplifier comprises first and second curved mirrors, a gain medium, a third mirror, and a mask. The gain medium is situated between the first and second curved mirrors at the focal point of each curved mirror. The first curved mirror directs and focuses a laser beam to pass through the gain medium to the second curved mirror which reflects and recollimates the laser beam. The gain medium amplifies and shapes the laser beam as the laser beam passes therethough. The third mirror reflects the laser beam, reflected from the second curved mirror, so that the laser beam bypasses the gain medium and return to the first curved mirror, thereby completing a cycle of a ring traversed by the laser beam. The mask defines at least one beam-clipping aperture through which the laser beam passes during a cycle. The gain medium is pumped, preferably using a suitable pumping laser. The laser amplifier can be used to increase the energy of continuous-wave or, especially, pulsed laser beams including pulses of femtosecond duration and relatively high pulse rate.

  10. Electrospun Amplified Fiber Optics

    PubMed Central

    2015-01-01

    All-optical signal processing is the focus of much research aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for efficient signal transmission. However, the complex fabrication methods involving high-temperature processes performed in a highly pure environment slow the fabrication process and make amplified components expensive with respect to an ideal, high-throughput, room temperature production. Here, we report on near-infrared polymer fiber amplifiers working over a band of ∼20 nm. The fibers are cheap, spun with a process entirely carried out at room temperature, and shown to have amplified spontaneous emission with good gain coefficients and low levels of optical losses (a few cm–1). The amplification process is favored by high fiber quality and low self-absorption. The found performance metrics appear to be suitable for short-distance operations, and the large variety of commercially available doping dyes might allow for effective multiwavelength operations by electrospun amplified fiber optics. PMID:25710188

  11. High input impedance amplifier

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard L.

    1995-01-01

    High input impedance amplifiers are provided which reduce the input impedance solely to a capacitive reactance, or, in a somewhat more complex design, provide an extremely high essentially infinite, capacitive reactance. In one embodiment, where the input impedance is reduced in essence, to solely a capacitive reactance, an operational amplifier in a follower configuration is driven at its non-inverting input and a resistor with a predetermined magnitude is connected between the inverting and non-inverting inputs. A second embodiment eliminates the capacitance from the input by adding a second stage to the first embodiment. The second stage is a second operational amplifier in a non-inverting gain-stage configuration where the output of the first follower stage drives the non-inverting input of the second stage and the output of the second stage is fed back to the non-inverting input of the first stage through a capacitor of a predetermined magnitude. These amplifiers, while generally useful, are very useful as sensor buffer amplifiers that may eliminate significant sources of error.

  12. Radiation and particle detector and amplifier

    NASA Technical Reports Server (NTRS)

    Schmidt, K. C. (Inventor)

    1973-01-01

    A radiation or charged particle detector is described which incorporates a channel multiplier structure to amplify the detected rays or particles. The channel multiplier structure has a support multiplying element with a longitudinal slot along one side. The element supports a pair of plates positioned contiguous with the slot. The plates funnel the particles or rays to be detected into the slotted aperture and the element, thus creating an effectively wide aperture detector of the windowless type.

  13. A micropower electrocardiogram amplifier.

    PubMed

    Fay, L; Misra, V; Sarpeshkar, R

    2009-10-01

    We introduce an electrocardiogram (EKG) preamplifier with a power consumption of 2.8 muW, 8.1 muVrms input-referred noise, and a common-mode rejection ratio of 90 dB. Compared to previously reported work, this amplifier represents a significant reduction in power with little compromise in signal quality. The improvement in performance may be attributed to many optimizations throughout the design including the use of subthreshold transistor operation to improve noise efficiency, gain-setting capacitors versus resistors, half-rail operation wherever possible, optimal power allocations among amplifier blocks, and the sizing of devices to improve matching and reduce noise. We envision that the micropower amplifier can be used as part of a wireless EKG monitoring system powered by rectified radio-frequency energy or other forms of energy harvesting like body vibration and body heat. PMID:23853270

  14. STABILIZED FEEDBACK AMPLIFIER

    DOEpatents

    Fishbine, H.L.; Sewell, C. Jr.

    1957-08-01

    Negative feedback amplifiers, and particularly a negative feedback circuit which is economical on amode power consumption, are described. Basically, the disclosed circuit comprises two tetrode tubes where the output of the first tube is capacitamce coupled to the grid of the second tube, which in turn has its plate coupled to the cathode of the first tube to form a degenerative feedback circuit. Operating potential for screen of the second tube is supplied by connecting the cathode resistor of the first tube to the screen, while the screen is by-passed to the cathode of its tube for the amplified frequencies. Also, the amplifier incorporates a circuit to stabilize the transconductance of the tubes by making the grid potential of each tube interdependent on anode currents of both lubes by voltage divider circuitry.

  15. Spatial Light Amplifier Modulators

    NASA Technical Reports Server (NTRS)

    Eng, Sverre T.; Olsson, N. Anders

    1992-01-01

    Spatial light amplifier modulators (SLAM's) are conceptual devices that effect two-dimensional spatial modulation in optical computing and communication systems. Unlike current spatial light modulators, these provide gain. Optical processors incorporating SLAM's designed to operate in reflection or transmission mode. Each element of planar SLAM array is optical amplifier - surface-emitting diode laser. Array addressed electrically with ac modulating signals superimposed on dc bias currents supplied to lasers. SLAM device provides both desired modulation and enough optical gain to enable splitting of output signal into many optical fibers without excessive loss of power.

  16. A grid amplifier

    NASA Technical Reports Server (NTRS)

    Kim, Moonil; Weikle, Robert M., II; Hacker, Jonathan B.; Delisio, Michael P.; Rutledge, David B.; Rosenberg, James J.; Smith, R. P.

    1991-01-01

    A 50-MESFET grid amplifier is reported that has a gain of 11 dB at 3.3 GHz. The grid isolates the input from the output by using vertical polarization for the input beam and horizontal polarization for the transmitted output beam. The grid unit cell is a two-MESFET differential amplifier. A simple calibration procedure allows the gain to be calculated from a relative power measurement. This grid is a hybrid circuit, but the structure is suitable for fabrication as a monolithic wafer-scale integrated circuit, particularly at millimeter wavelengths.

  17. Universal signal conditioning amplifier

    NASA Technical Reports Server (NTRS)

    Larson, William E.; Hallberg, Carl; Medelius, Pedro J.

    1994-01-01

    Engineers at NASA's Kennedy Space Center have designed a signal conditioning amplifier which automatically matches itself to almost any kind of transducer. The product, called Universal Signal Conditioning Amplifier (USCA), uses state-of-the-art technologies to deliver high accuracy measurements. USCA's features which can be either programmable or automated include: voltage, current, or pulsed excitation, unlimited resolution gain, digital filtering and both analog and digital output. USCA will be used at Kennedy Space Center's launch pads for environmental measurements such as vibrations, strains, temperatures and overpressures. USCA is presently being commercialized through a co-funded agreement between NASA, the State of Florida, and Loral Test and Information Systems, Inc.

  18. Molecular charge contact biosensing based on the interaction of biologically modified magnetic beads with an ion-sensitive field effect transistor.

    PubMed

    Miyazawa, Yuuya; Sakata, Toshiya

    2014-05-01

    In this article, we report a novel method of biomolecular recognition based on the molecular charge contact (MCC). As one of the MCC biosensing method, the interaction between DNA-coated magnetic beads and a silicon-based semiconductor, an ion-sensitive field effect transistor (ISFET) could be detected for DNA molecular recognition events using the principle of the field effect, which enables detecting ionic or molecular charges. After DNA-coated magnetic beads had been introduced and brought in contact with the gate surface by a magnet, the threshold voltage of the ISFET was shifted in the positive direction by immobilization, hybridization and extension reaction of DNA molecules on magnetic beads. This positive shift was based on the increase in negative charges of the phosphate groups in them. Then, the ISFET device could be reused a couple of dozen times continuously and cost-effectively because the oligonucleotide probes were tethered to the magnetic beads, but this was not done directly on the gate surface of the ISFET. Moreover, the MCC biosensing method enabled discrimination of a single nucleotide polymorphism. By creating an interaction of magnetic beads with the semiconductor, we can expect enhancement of the reaction efficiency in a solution and reuse of the device by separating the reaction field from the sensing substrate. PMID:24595376

  19. Interfacial Charge Transfer in Dye-Sensitized Solar Cells Using SCN-Free Terpyridine-Coordinated Ru Complex Dye and Co Complex Redox Couples.

    PubMed

    Kono, Takahiro; Masaki, Naruhiko; Nishikawa, Masahiro; Tamura, Rei; Matsuzaki, Hiroyuki; Kimura, Mutsumi; Mori, Shogo

    2016-07-01

    The efficiency of dye-sensitized solar cells (DSSCs) using Ru complex dyes and Co complex redox couples has been increased with a strategy to prevent charge recombination via the addition of bulky or lengthy peripheral units to the dyes. However, despite the efforts, most of the DSSCs are still suffering from nonunity quantum efficiency and fast recombination. We examine the effect of SCN ligand, which has been used for many Ru complex dyes and could attract positively charged Co complexes. We find that replacing the ligands with 2,6-bis(2'-(4'-trifluoromethyl)pyrazolyl)pyridine increases the quantum efficiency and electron lifetime. With the combination of the replacement of SCN ligands and the addition of bulky moiety, ∼80% external quantum efficiency is achieved. These suggest that not only the addition of a blocking effect but also the reduction of electrostatic and dispersion forces between dyes and Co complexes are essential to control the charge separation and recombination processes. PMID:27328462

  20. Influence of TiO2 nanotube morphology and TiCl4 treatment on the charge transfer in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Lee, Sun Hong; Chae, Sang Youn; Hwang, Yun Jeong; Koo, Kee-Kahb; Joo, Oh-Shim

    2013-09-01

    Dye-sensitized solar cells (DSSCs) were fabricated using TiO2 nanoparticles (NPs), TiO2 nanotube arrays (NTAs), and surface-modified NTAs with a TiCl4 treatment. The photovoltaic efficiencies of the DSSCs using TiO2 NP, NTA, and TiCl4-treated NTA electrodes are 4.25, 4.74, and 7.47 %, respectively. The highest performance was observed with a TiCl4-treated TiO2 NTA photoanode, although in the case of the latter two electrodes, the amounts of N719 dye adsorbed were similar and 68 % of that of the NP electrode. Electrochemical impedance measurements show that the overall resistance, including the charge-transfer resistance, was smaller with NTA morphologies than with NP morphologies. We suggest that a different electron transfer mechanism along the one-dimensional nanostructure of the TiO2 NTAs contributes to the smaller charge-transfer resistance, resulting in a higher short circuit current ( J sc), even at lower dye adsorption. Furthermore, the TiCl4-treated NTAs showed even smaller charge-transfer resistance, resulting in the highest J sc value, because the downward shift in the conduction band edge improves the electron injection efficiency from the excited dye into the TiCl4-treated TiO2 electrodes.

  1. Negative electrospray ionization on porous supporting tips for mass spectrometric analysis: electrostatic charging effect on detection sensitivity and its application to explosive detection.

    PubMed

    Wong, Melody Yee-Man; Man, Sin-Heng; Che, Chi-Ming; Lau, Kai-Chung; Ng, Kwan-Ming

    2014-03-21

    The simplicity and easy manipulation of a porous substrate-based ESI-MS technique have been widely applied to the direct analysis of different types of samples in positive ion mode. However, the study and application of this technique in negative ion mode are sparse. A key challenge could be due to the ease of electrical discharge on supporting tips upon the application of negative voltage. The aim of this study is to investigate the effect of supporting materials, including polyester, polyethylene and wood, on the detection sensitivity of a porous substrate-based negative ESI-MS technique. By using nitrobenzene derivatives and nitrophenol derivatives as the target analytes, it was found that the hydrophobic materials (i.e., polyethylene and polyester) with a higher tendency to accumulate negative charge could enhance the detection sensitivity towards nitrobenzene derivatives via electron-capture ionization; whereas, compounds with electron affinities lower than the cut-off value (1.13 eV) were not detected. Nitrophenol derivatives with pKa smaller than 9.0 could be detected in the form of deprotonated ions; whereas polar materials (i.e., wood), which might undergo competitive deprotonation with the analytes, could suppress the detection sensitivity. With the investigation of the material effects on the detection sensitivity, the porous substrate-based negative ESI-MS method was developed and applied to the direct detection of two commonly encountered explosives in complex samples. PMID:24492411

  2. IonCCD™ for direct position-sensitive charged-particle detection: from electrons and keV ions to hyperthermal biomolecular ions

    SciTech Connect

    Hadjar, Omar; Johnson, Grant E.; Laskin, Julia; Kibelka, Gottfried; Shill, Scott M.; Kuhn, Ken; Cameron, Chad; Kassan, Scott

    2011-04-01

    A novel charged-particle sensitive, pixel based detector array is described and its usage is demonstrated for a variety of applications, from detection of elemental particles (electrons) to hyper-thermal large biomolecular positive and negative ions including keV light atomic and molecular ions. The array detector is a modified light-sensitive charged coupled device (CCD). The IonCCDTM was engineered for direct charged particle detection by replacing the semi-conductor part of the CCD pixel by a conductor1. In contrast with the CCD, where the semi-conductive pixel is responsible for electron-hole pair formation upon photon bombardment, the IonCCD uses a capacitor coupled to the conductive electrode for direct charge integration. The detector can be operated from atmospheric pressure to high vacuum since no high voltages are needed. The IonCCD, presented in this work is an array of 2126 active pixels with 21 um pixel width and 3 um pixel gap. The detection area is 1.5x51mm2 where 1.5 mm and 51 mm are pixel and detector array length, respectively. The result is a one-dimensional position-sensitive detector with 24 um spatial resolution and 88 % pixel area ratio (PAR). In this work we demonstrate the capabilities and the performance of the detector. For the first time we show the direct detection of 250 eV electrons providing linearity response and detection efficiency of the IonCCD as function of electron beam current. Using positive ions from and electron impact source (E-I), we demonstrate that the detection efficiency of the IonCCD is virtually independent of particle energy [250 eV, 1250 eV], particle impact angle [45o, 90o] and particle flux. By combining the IonCCD with a double focusing sector field of Mattauch-Herzog geometry (M-H), we demonstrate fast acquisition of mass spectra in direct air sniffing mode. A first step towards fast in vivo breath analysis is presented. Detection of hyper-thermal biomolecular ions produced using an electrospray ionization

  3. Fourier plane image amplifier

    DOEpatents

    Hackel, L.A.; Hermann, M.R.; Dane, C.B.; Tiszauer, D.H.

    1995-12-12

    A solid state laser is frequency tripled to 0.3 {micro}m. A small portion of the laser is split off and generates a Stokes seed in a low power oscillator. The low power output passes through a mask with the appropriate hole pattern. Meanwhile, the bulk of the laser output is focused into a larger stimulated Brillouin scattering (SBS) amplifier. The low power beam is directed through the same cell in the opposite direction. The majority of the amplification takes place at the focus which is the fourier transform plane of the mask image. The small holes occupy large area at the focus and thus are preferentially amplified. The amplified output is now imaged onto the multichip module where the holes are drilled. Because of the fourier plane amplifier, only about 1/10th the power of a competitive system is needed. This concept allows less expensive masks to be used in the process and requires much less laser power. 1 fig.

  4. Improved RF Isolation Amplifier

    NASA Technical Reports Server (NTRS)

    Stevens, G. L.; Macconnell, J.

    1985-01-01

    Circuit has high reverse isolation and wide bandwidth. Wideband isolation amplifier has low intermodulation distortion and high reverse isolation. Circuit does not require selected or matched components or directional coupling device. Circuit used in applications requiring high reverse isolation such as receiver intermediate-frequency (IF) strips and frequency distribution systems. Also applicable in RF and video signaling.

  5. Fourier plane image amplifier

    DOEpatents

    Hackel, Lloyd A.; Hermann, Mark R.; Dane, C. Brent; Tiszauer, Detlev H.

    1995-01-01

    A solid state laser is frequency tripled to 0.3 .mu.m. A small portion of the laser is split off and generates a Stokes seed in a low power oscillator. The low power output passes through a mask with the appropriate hole pattern. Meanwhile, the bulk of the laser output is focused into a larger stimulated Brillouin scattering (SBS) amplifier. The low power beam is directed through the same cell in the opposite direction. The majority of the amplification takes place at the focus which is the fourier transform plane of the mask image. The small holes occupy large area at the focus and thus are preferentially amplified. The amplified output is now imaged onto the multichip module where the holes are drilled. Because of the fourier plane amplifier, only .about.1/10th the power of a competitive system is needed. This concept allows less expensive masks to be used in the process and requires much less laser power.

  6. Ab Initio Simulation of Charge Transfer at the Semiconductor Quantum Dot/TiO 2 Interface in Quantum Dot-Sensitized Solar Cells

    SciTech Connect

    Xin, Xukai; Li, Bo; Jung, Jaehan; Yoon, Young Jun; Biswas, Rana; Lin, Zhiqun

    2014-07-24

    Quantum dot-sensitized solar cells (QDSSCs) have emerged as a promising solar architecture for next-generation solar cells. The QDSSCs exhibit a remarkably fast electron transfer from the quantum dot (QD) donor to the TiO2 acceptor with size quantization properties of QDs that allows for the modulation of band energies to control photoresponse and photoconversion efficiency of solar cells. In order to understand the mechanisms that underpin this rapid charge transfer, the electronic properties of CdSe and PbSe QDs with different sizes on the TiO2 substrate are simulated using a rigorous ab initio density functional method. Our method capitalizes on localized orbital basis set, which is computationally less intensive. Quite intriguingly, a remarkable set of electron bridging states between QDs and TiO2 occurring via the strong bonding between the conduction bands of QDs and TiO2 is revealed. Such bridging states account for the fast adiabatic charge transfer from the QD donor to the TiO2 acceptor, and may be a general feature for strongly coupled donor/acceptor systems. All the QDs/TiO2 systems exhibit type II band alignments, with conduction band offsets that increase with the decrease in QD size. This facilitates the charge transfer from QDs donors to TiO2 acceptors and explains the dependence of the increased charge transfer rate with the decreased QD size.

  7. Ultraflexible organic amplifier with biocompatible gel electrodes.

    PubMed

    Sekitani, Tsuyoshi; Yokota, Tomoyuki; Kuribara, Kazunori; Kaltenbrunner, Martin; Fukushima, Takanori; Inoue, Yusuke; Sekino, Masaki; Isoyama, Takashi; Abe, Yusuke; Onodera, Hiroshi; Someya, Takao

    2016-01-01

    In vivo electronic monitoring systems are promising technology to obtain biosignals with high spatiotemporal resolution and sensitivity. Here we demonstrate the fabrication of a biocompatible highly conductive gel composite comprising multi-walled carbon nanotube-dispersed sheet with an aqueous hydrogel. This gel composite exhibits admittance of 100 mS cm(-2) and maintains high admittance even in a low-frequency range. On implantation into a living hypodermal tissue for 4 weeks, it showed a small foreign-body reaction compared with widely used metal electrodes. Capitalizing on the multi-functional gel composite, we fabricated an ultrathin and mechanically flexible organic active matrix amplifier on a 1.2-μm-thick polyethylene-naphthalate film to amplify (amplification factor: ∼200) weak biosignals. The composite was integrated to the amplifier to realize a direct lead epicardial electrocardiography that is easily spread over an uneven heart tissue. PMID:27125910

  8. Ultraflexible organic amplifier with biocompatible gel electrodes

    NASA Astrophysics Data System (ADS)

    Sekitani, Tsuyoshi; Yokota, Tomoyuki; Kuribara, Kazunori; Kaltenbrunner, Martin; Fukushima, Takanori; Inoue, Yusuke; Sekino, Masaki; Isoyama, Takashi; Abe, Yusuke; Onodera, Hiroshi; Someya, Takao

    2016-04-01

    In vivo electronic monitoring systems are promising technology to obtain biosignals with high spatiotemporal resolution and sensitivity. Here we demonstrate the fabrication of a biocompatible highly conductive gel composite comprising multi-walled carbon nanotube-dispersed sheet with an aqueous hydrogel. This gel composite exhibits admittance of 100 mS cm-2 and maintains high admittance even in a low-frequency range. On implantation into a living hypodermal tissue for 4 weeks, it showed a small foreign-body reaction compared with widely used metal electrodes. Capitalizing on the multi-functional gel composite, we fabricated an ultrathin and mechanically flexible organic active matrix amplifier on a 1.2-μm-thick polyethylene-naphthalate film to amplify (amplification factor: ~200) weak biosignals. The composite was integrated to the amplifier to realize a direct lead epicardial electrocardiography that is easily spread over an uneven heart tissue.

  9. Real-time tuning of a double quantum dot using a Josephson parametric amplifier

    NASA Astrophysics Data System (ADS)

    Stehlik, J.; Liu, Y.-Y.; Quintana, C. M.; Eichler, C.; Hartke, T. R.; Petta, J. R.

    Josephson parametric amplifiers (JPAs) have enabled advances in readout of quantum systems. Here we demonstrate JPA-assisted readout of a cavity-coupled double quantum dot (DQD). Utilizing a JPA we improve the signal-to-noise ratio (SNR) by a factor of 2000 compared to the situation with the parametric amplifier turned off. At an interdot charge transition we achieve a SNR of 76 (19 dB) with an integration time τ = 400 ns, which is limited by the linewidth of our cavity. By measuring the SNR as a function of τ we extract an equivalent charge sensitivity of 8 ×10-5 e /√{ Hz} . We develop a dual-gate-voltage rastering scheme that allows us to acquire a DQD charge stability diagram in just 20 ms. Such rapid data acquisition rates enable device tuning in live ``video-mode,'' where the results of parameter changes are immediately displayed. Live tuning allows the DQD confinement potential to be rapidly tuned, a capability that will become increasingly important as semiconductor spin qubits are scaled to a larger number of dots. Research is supported by the Packard Foundation, ARO Grant No. W911NF-15-1-0149, DARPA QuEST Grant No. HR0011-09-1-0007, and the NSF (Grants No. DMR-1409556 and DMR-1420541).

  10. Nanoscale femtosecond imaging of transient hot solid density plasmas with elemental and charge state sensitivity using resonant coherent diffraction

    NASA Astrophysics Data System (ADS)

    Kluge, T.; Bussmann, M.; Chung, H.-K.; Gutt, C.; Huang, L. G.; Zacharias, M.; Schramm, U.; Cowan, T. E.

    2016-03-01

    Here, we propose to exploit the low energy bandwidth, small wavelength, and penetration power of ultrashort pulses from XFELs for resonant Small Angle Scattering (SAXS) on plasma structures in laser excited plasmas. Small angle scattering allows to detect nanoscale density fluctuations in forward scattering direction. Typically, the SAXS signal from laser excited plasmas is expected to be dominated by the free electron distribution. We propose that the ionic scattering signal becomes visible when the X-ray energy is in resonance with an electron transition between two bound states (resonant coherent X-ray diffraction). In this case, the scattering cross-section dramatically increases so that the signal of X-ray scattering from ions silhouettes against the free electron scattering background which allows to measure the opacity and derived quantities with high spatial and temporal resolution, being fundamentally limited only by the X-ray wavelength and timing. Deriving quantities such as ion spatial distribution, charge state distribution, and plasma temperature with such high spatial and temporal resolution will make a vast number of processes in shortpulse laser-solid interaction accessible for direct experimental observation, e.g., hole-boring and shock propagation, filamentation and instability dynamics, electron transport, heating, and ultrafast ionization dynamics.

  11. Probing sensitivity to charged scalars through partial differential widths: τ →K π π ντ decays

    NASA Astrophysics Data System (ADS)

    Mileo, Nicolas; Kiers, Ken; Szynkman, Alejandro

    2015-04-01

    We define and test C P -even and C P -odd partial differential widths for the process τ →K π π ντ assuming that an intermediate heavy charged scalar contributes to the decay amplitude. Adopting a model-independent approach, we use a Monte Carlo simulation in order to study the number of events needed to recover information on the new physics from these observables. Our analysis of the C P -odd observables indicates that the magnitude of fHηP , which is related to the new-physics contribution, can be recovered with an uncertainty smaller than 3% for 3 ×1 06 events. This number of events would also allow one to retrieve certain parameters appearing in the Standard Model amplitude at the percent level. In addition, we discuss the possibility of using the proposed observables to study specific models involving two Higgs doublets, such as the aligned two-Higgs-doublet model. This analysis is undertaken within the context of the upcoming super B-factories, which are expected to provide a considerably larger number of events than that which was supplied by the B-factories. Moreover, a similar set of observables could be employed to study other decay modes such as τ →π π π ντ , τ →K K π ντ and τ →K K K ντ.

  12. Tapered fiber amplifier

    NASA Astrophysics Data System (ADS)

    Russell, Stephen D.; Stamnitz, Timothy C.

    1990-07-01

    A tapered optical fiber amplifier is designed to provide for long-distance, un-repeatered fiber optic communications. Two single-mode fiber portions are tapered to efficiently intensify and couple an information signal from a laser diode and a pump signal at a shorter wavelength into a fused, tapered single-mode fiber optic coupler. The concentrated information signal and concentrated pump signal are combined via the coupler which is coupled to a several-kilometer length of a relatively small core diametered single-mode fiber to create nonlinear optical effect (stimulated Raman scattering) (SRS). The SRS causes Raman shift of the pump light into the small core diametered single-mode fiber length, thereby generating SRS to result in a signal amplification and an efficient extraction of the amplified signal via the tapered output fiber portion or pigtail.

  13. Monolithic dye laser amplifier

    DOEpatents

    Kuklo, Thomas C.

    1993-01-01

    A fluid dye laser amplifier for amplifying a dye beam by pump beams has a channel structure defining a channel through which a laseable fluid flows and the dye and pump beams pass transversely to one another through a lasing region. The channel structure is formed with two pairs of mutually spaced-apart and mutually confronting glass windows, which are interlocked and make surface-contacts with one another and surround the lasing region. One of the glass window pairs passes the dye beam and the other passes the pump beams therethrough and through the lasing region. Where these glass window pieces make surface-contacts, glue is used to join the pieces together to form a monolithic structure so as to prevent the dye in the fluid passing through the channel from entering the space between the mutually contacting glass window pieces.

  14. Monolithic dye laser amplifier

    DOEpatents

    Kuklo, T.C.

    1993-03-30

    A fluid dye laser amplifier for amplifying a dye beam by pump beams has a channel structure defining a channel through which a laseable fluid flows and the dye and pump beams pass transversely to one another through a lasing region. The channel structure is formed with two pairs of mutually spaced-apart and mutually confronting glass windows, which are interlocked and make surface-contacts with one another and surround the lasing region. One of the glass window pairs passes the dye beam and the other passes the pump beams therethrough and through the lasing region. Where these glass window pieces make surface-contacts, glue is used to join the pieces together to form a monolithic structure so as to prevent the dye in the fluid passing through the channel from entering the space between the mutually contacting glass window pieces.

  15. STABILIZED TRANSISTOR AMPLIFIER

    DOEpatents

    Noe, J.B.

    1963-05-01

    A temperature stabilized transistor amplifier having a pair of transistors coupled in cascade relation that are capable of providing amplification through a temperature range of - 100 un. Concent 85% F to 400 un. Concent 85% F described. The stabilization of the amplifier is attained by coupling a feedback signal taken from the emitter of second transistor at a junction between two serially arranged biasing resistances in the circuit of the emitter of the second transistor to the base of the first transistor. Thus, a change in the emitter current of the second transistor is automatically corrected by the feedback adjustment of the base-emitter potential of the first transistor and by a corresponding change in the base-emitter potential of the second transistor. (AEC)

  16. Man-Amplifying Exoskeleton

    NASA Astrophysics Data System (ADS)

    Rosheim, Mark E.

    1990-03-01

    This paper describes a design for a man-amplifying exoskeleton, an electrically powered, articulated frame worn by an operator. The design features modular construction and employ anthropomorphic pitch-yaw joints for arms and legs. These singularity-free designs offer a significant advancement over simple pivot-type joints used in older designs. Twenty-six degrees-of-freedom excluding the hands gives the Man-Amplifier its unique dexterity. A five hundred-pound load capacity is engineered for a diverse range of tasks. Potential applications in emergency rescue work, restoring functionality to the handicapped, and military applications ranging from material handling to an elite fighting core are discussed. A bibliography concludes this paper.

  17. PEAK LIMITING AMPLIFIER

    DOEpatents

    Goldsworthy, W.W.; Robinson, J.B.

    1959-03-31

    A peak voltage amplitude limiting system adapted for use with a cascade type amplifier is described. In its detailed aspects, the invention includes an amplifier having at least a first triode tube and a second triode tube, the cathode of the second tube being connected to the anode of the first tube. A peak limiter triode tube has its control grid coupled to thc anode of the second tube and its anode connected to the cathode of the second tube. The operation of the limiter is controlled by a bias voltage source connected to the control grid of the limiter tube and the output of the system is taken from the anode of the second tube.

  18. Helical Fiber Amplifier

    DOEpatents

    Koplow, Jeffrey P.; Kliner, Dahy; Goldberg, Lew

    2002-12-17

    A multi-mode gain fiber is provided which affords substantial improvements in the maximum pulse energy, peak power handling capabilities, average output power, and/or pumping efficiency of fiber amplifier and laser sources while maintaining good beam quality (comparable to that of a conventional single-mode fiber source). These benefits are realized by coiling the multimode gain fiber to induce significant bend loss for all but the lowest-order mode(s).

  19. Solvent sensitive intramolecular charge transfer dynamics in the excited states of 4-N,N-dimethylamino-4'-nitrobiphenyl.

    PubMed

    Ghosh, Rajib; Nandi, Amitabha; Palit, Dipak K

    2016-03-21

    Organic molecules substituted with the nitro group show efficient nonlinear optical (NLO) properties, which are a consequence of the strong intramolecular charge transfer (ICT) character of the molecules because of the strong electron withdrawing nature of the nitro group and rapid responsiveness because of highly movable π-electrons. Dynamics of the ICT process in the excited states of a push-pull biphenyl derivative, namely, 4-N,N-dimethylamino-4'-nitrobiphenyl (DNBP), an efficient NLO material, has been investigated using ultrafast transient absorption spectroscopy. The experimental results have been corroborated with DFT and TDDFT calculations. In solvents of large polarity, e.g. acetonitrile, the ultrafast ICT process of DNBP is associated with the barrierless twisting of the N,N-dimethylaniline (DMA) group with respect to the nitrobenzene moiety to populate the twisted ICT (or TICT) state, and the rate of this process is solely governed by the viscosity of the medium. In solvents of moderate polarity, e.g. ethyl acetate, the rate of the twisting process is significantly slowed down and the LE and TICT states remain in equilibrium because of a low energy barrier for interconversion between these two states. By further lowering the polarity of the solvent, e.g. in dioxane, the twisting process is completely retarded. In nonpolar solvents, e.g. cyclohexane, a reverse twisting motion towards the planar geometry (i.e. the PICT process) has been evident in the excited state dynamics. In this solvent, the S1 state undergoes an ultrafast intersystem crossing to the triplet state because of its close proximity with the T2 state. PMID:26907751

  20. Improved-Bandwidth Transimpedance Amplifier

    NASA Technical Reports Server (NTRS)

    Chapsky, Jacob

    2009-01-01

    The widest available operational amplifier, with the best voltage and current noise characteristics, is considered for transimpedance amplifier (TIA) applications where wide bandwidth is required to handle fast rising input signals (as for time-of-flight measurement cases). The added amplifier inside the TIA feedback loop can be configured to have slightly lower voltage gain than the bandwidth reduction factor.

  1. Multiple pass laser amplifier system

    DOEpatents

    Brueckner, Keith A.; Jorna, Siebe; Moncur, N. Kent

    1977-01-01

    A laser amplification method for increasing the energy extraction efficiency from laser amplifiers while reducing the energy flux that passes through a flux limited system which includes apparatus for decomposing a linearly polarized light beam into multiple components, passing the components through an amplifier in delayed time sequence and recombining the amplified components into an in phase linearly polarized beam.

  2. Response of an environment-sensitive intramolecular charge transfer probe towards solubilization of liposome membranes by a non-ionic detergent: Association and dissociation kinetics

    NASA Astrophysics Data System (ADS)

    Paul, Bijan Kumar; Guchhait, Nikhil

    2012-10-01

    The present report describes an endeavor to follow the solubilization of DMPC and DMPG liposome membranes by a non-ionic detergent Triton X-100 on the lexicon of environment-sensitive intramolecular charge transfer (ICT) photophysics of an extrinsic molecular probe 5-(4-dimethylamino-phenyl)-penta-2, 4-dienoic acid methyl ester (DPDAME). The prospective applicability of the probe to function as a reporter for detergent-sequestered solubilization of liposome membranes is argued on the basis of comparison of the spectral properties of the probe in various environments. Fluorescence anisotropy study delineates the degree of motional restriction imposed on the probe in different microheterogeneous assemblies. The kinetics of association of the probe with the liposome membranes and the dissociation kinetics of TX-100-sequestered solubilization process of the liposomes have been monitored by the stopped-flow fluorescence technique and the results are rationalized in relevance to fluorescence anisotropy study.

  3. Gas amplified ionization detector for gas chromatography

    DOEpatents

    Huston, Gregg C.

    1992-01-01

    A gas-amplified ionization detector for gas chromatrography which possesses increased sensitivity and a very fast response time. Solutes eluding from a gas chromatographic column are ionized by UV photoionization of matter eluting therefrom. The detector is capable of generating easily measured voltage signals by gas amplification/multiplication of electron products resulting from the UV photoionization of at least a portion of each solute passing through the detector.

  4. Highly Efficient Visible-to-NIR Luminescence of Lanthanide(III) Complexes with Zwitterionic Ligands Bearing Charge-Transfer Character: Beyond Triplet Sensitization.

    PubMed

    Pan, Mei; Du, Bin-Bin; Zhu, Yi-Xuan; Yue, Mei-Qin; Wei, Zhang-Wen; Su, Cheng-Yong

    2016-02-01

    Two zwitterionic-type ligands featuring π-π* and intraligand charge-transfer (ILCT) excited states, namely 1,1'-(2,3,5,6-tetramethyl-1,4-phenylene)bis(methylene)dipyridinium-4-olate (TMPBPO) and 1-dodecylpyridin-4(1 H)-one (DOPO), have been prepared and applied to the assembly of lanthanide coordination complexes in an effort to understand the ligand-direction effect on the structure of the Ln complexes and the ligand sensitization effect on the luminescence of the Ln complexes. Due to the wide-band triplet states plus additional ILCT excitation states extending into lower energy levels, broadly and strongly sensitized photoluminescence of f→f transitions from various Ln(3+) ions were observed to cover the visible to near-infrared (NIR) regions. Among which, the Pr, Sm, Dy, and Tm complexes simultaneously display both strong visible and NIR emissions. Based on the isostructural feature of the Ln complexes, color tuning and single-component white light was achieved by preparation of solid solutions of the ternary systems Gd-Eu-Tb (for TMPBPO) and La-Eu-Tb and La-Dy-Sm (for DOPO). Moreover, the visible and NIR luminescence lifetimes of the Ln complexes with the TMPBPO ligand were investigated from 77 to 298 K, revealing a strong temperature dependence of the Tm(3+) ((3) H4 ) and Yb(3+) ((2) F5/2 ) decay dynamics, which has not been explored before for their coordination complexes. PMID:26784018

  5. Amplifying Electrochemical Indicators

    NASA Technical Reports Server (NTRS)

    Fan, Wenhong; Li, Jun; Han, Jie

    2004-01-01

    Dendrimeric reporter compounds have been invented for use in sensing and amplifying electrochemical signals from molecular recognition events that involve many chemical and biological entities. These reporter compounds can be formulated to target specific molecules or molecular recognition events. They can also be formulated to be, variously, hydrophilic or amphiphilic so that they are suitable for use at interfaces between (1) aqueous solutions and (2) electrodes connected to external signal-processing electronic circuits. The invention of these reporter compounds is expected to enable the development of highly miniaturized, low-power-consumption, relatively inexpensive, mass-producible sensor units for diverse applications.

  6. REGENERATIVE TRANSISTOR AMPLIFIER

    DOEpatents

    Kabell, L.J.

    1958-11-25

    Electrical circults for use in computers and the like are described. particularly a regenerative bistable transistor amplifler which is iurned on by a clock signal when an information signal permits and is turned off by the clock signal. The amplifier porforms the above function with reduced power requirements for the clock signal and circuit operation. The power requirements are reduced in one way by employing transformer coupling which increases the collector circuit efficiency by eliminating the loss of power in the collector load resistor.

  7. Effective amplifier noise for an optical receiver based on linear mode avalanche photodiodes

    NASA Technical Reports Server (NTRS)

    Chen, C.-C.

    1989-01-01

    The rms noise charge induced by the amplifier for an optical receiver based on the linear-mode avalanche photodiode (APD) was analyzed. It is shown that for an amplifier with a 1-pF capacitor and a noise temperature of 100 K, the rms noise charge due to the amplifier is about 300. Since the noise charge must be small compared to the signal gain, APD gains on the order of 1000 will be required to operate the receiver in the linear mode.

  8. In-situ experimental investigations of electron space-charge instabilities and noise mechanisms in a reentrant crossed-field amplifier via distributed-cathode emission and gated-beam injection

    SciTech Connect

    Ye, J.Z.; MacGregor, R.; Chan, C.; Ruden, T.E.

    1995-12-31

    Experimental investigations of the true physical conditions inside the crossed-field devices are of fundamental importance for the understanding of the operation of these devices and may lead to eventual improvement of the present tubes. At Northeastern University, tube research has taken up a combined approach of in situ plasma diagnostics and computer simulation using two frequency scaled CFA`s as test vehicles. A collection of temporal and time-averaged diagnostic techniques have been developed through the research. Probe measurements as well as device performance of the linear CFA and the beam-injected, reentrant CFA have been directly compared with computer simulation results from MASK and NEAMP codes. The authors have recently incorporated in their reentrant CFA a secondary emission cathode for the purpose of gaining insight on improving the noise performance of both military and commercial devices. It has long been speculated, and appears more so as a result of the improved diagnostic techniques, that the instabilities in the space charge cloud are the major source of noise in crossed-field devices. Long electron transit time facilitates large-scale energy exchanges between hub electrons and eliminates the condition for the classical Brillouin flow. Their time-averaged density measurements confirmed that electron cloud extends beyond that predicted by the classical theory; preliminary observations showed organized space charge oscillations for static operating regimes. These oscillations can interact with the applied RF drive signal at different levels resulting in noise on the RF circuit. Other instabilities associated with the cathode secondary emission and due to reentrant electrons are, among other factors, evaluated in terms of their contribution to the turbulent behavior via spatial probes that monitor the anode current, back bombardment current and space charge fluctuation.

  9. DIAMOND AMPLIFIED PHOTOCATHODES.

    SciTech Connect

    SMEDLEY,J.; BEN-ZVI, I.; BOHON, J.; CHANG, X.; GROVER, R.; ISAKOVIC, A.; RAO, T.; WU, Q.

    2007-11-26

    High-average-current linear electron accelerators require photoinjectors capable of delivering tens to hundreds of mA average current, with peak currents of hundreds of amps. Standard photocathodes face significant challenges in meeting these requirements, and often have short operational lifetimes in an accelerator environment. We report on recent progress toward development of secondary emission amplifiers for photocathodes, which are intended to increase the achievable average current while protecting the cathode from the accelerator. The amplifier is a thin diamond wafer which converts energetic (few keV) primary electrons into hundreds of electron-hole pairs via secondary electron emission. The electrons drift through the diamond under an external bias and are emitted into vacuum via a hydrogen-terminated surface with negative electron affinity (NEA). Secondary emission gain of over 200 has been achieved. Two methods of patterning diamond, laser ablation and reactive-ion etching (RIE), are being developed to produce the required geometry. A variety of diagnostic techniques, including FTIR, SEM and AFM, have been used to characterize the diamonds.

  10. Universal Signal Conditioning Amplifier

    NASA Technical Reports Server (NTRS)

    Kinney, Frank

    1997-01-01

    The Technological Research and Development Authority (TRDA) and NASA-KSC entered into a cooperative agreement in March of 1994 to achieve the utilization and commercialization of a technology development for benefiting both the Space Program and U.S. industry on a "dual-use basis". The technology involved in this transfer is a new, unique Universal Conditioning Amplifier (USCA) used in connection with various types of transducers. The project was initiated in partnership with I-Net Corporation, Lockheed Martin Telemetry & Instrumentation (formerly Loral Test and Information Systems) and Brevard Community College. The project consists of designing, miniaturizing, manufacturing, and testing an existing prototype of USCA that was developed for NASA-KSC by the I-Net Corporation. The USCA is a rugged and field-installable self (or remotely)- programmable amplifier that works in combination with a tag random access memory (RAM) attached to various types of transducers. This summary report comprises performance evaluations, TRDA partnership tasks, a project summary, project milestones and results.

  11. Stereoscopy Amplifies Emotions Elicited by Facial Expressions

    PubMed Central

    Kätsyri, Jari; Häkkinen, Jukka

    2015-01-01

    Mediated facial expressions do not elicit emotions as strongly as real-life facial expressions, possibly due to the low fidelity of pictorial presentations in typical mediation technologies. In the present study, we investigated the extent to which stereoscopy amplifies emotions elicited by images of neutral, angry, and happy facial expressions. The emotional self-reports of positive and negative valence (which were evaluated separately) and arousal of 40 participants were recorded. The magnitude of perceived depth in the stereoscopic images was manipulated by varying the camera base at 15, 40, 65, 90, and 115 mm. The analyses controlled for participants’ gender, gender match, emotional empathy, and trait alexithymia. The results indicated that stereoscopy significantly amplified the negative valence and arousal elicited by angry expressions at the most natural (65 mm) camera base, whereas stereoscopy amplified the positive valence elicited by happy expressions in both the narrowed and most natural (15–65 mm) base conditions. Overall, the results indicate that stereoscopy amplifies the emotions elicited by mediated emotional facial expressions when the depth geometry is close to natural. The findings highlight the sensitivity of the visual system to depth and its effect on emotions. PMID:27551358

  12. Stereoscopy Amplifies Emotions Elicited by Facial Expressions.

    PubMed

    Hakala, Jussi; Kätsyri, Jari; Häkkinen, Jukka

    2015-12-01

    Mediated facial expressions do not elicit emotions as strongly as real-life facial expressions, possibly due to the low fidelity of pictorial presentations in typical mediation technologies. In the present study, we investigated the extent to which stereoscopy amplifies emotions elicited by images of neutral, angry, and happy facial expressions. The emotional self-reports of positive and negative valence (which were evaluated separately) and arousal of 40 participants were recorded. The magnitude of perceived depth in the stereoscopic images was manipulated by varying the camera base at 15, 40, 65, 90, and 115 mm. The analyses controlled for participants' gender, gender match, emotional empathy, and trait alexithymia. The results indicated that stereoscopy significantly amplified the negative valence and arousal elicited by angry expressions at the most natural (65 mm) camera base, whereas stereoscopy amplified the positive valence elicited by happy expressions in both the narrowed and most natural (15-65 mm) base conditions. Overall, the results indicate that stereoscopy amplifies the emotions elicited by mediated emotional facial expressions when the depth geometry is close to natural. The findings highlight the sensitivity of the visual system to depth and its effect on emotions. PMID:27551358

  13. Ways to suppress click and pop for class D amplifiers

    NASA Astrophysics Data System (ADS)

    Haishi, Wang; Bo, Zhang; Jiang, Sun

    2012-08-01

    Undesirable audio click and pop may be generated in a speaker or headphone. Compared to linear (class A/B/AB) amplifiers, class D amplifiers that comprise of an input stage and a modulation stage are more prone to producing click and pop. This article analyzes sources that generate click and pop in class D amplifiers, and corresponding ways to suppress them. For a class D amplifier with a single-ended input, click and pop is likely to be due to two factors. One is from a voltage difference (VDIF) between the voltage of an input capacitance (VCIN) and a reference voltage (VREF) of the input stage, and the other one is from the non-linear switching during the setting up of the bias and feedback voltages/currents (BFVC) of the modulation stage. In this article, a fast charging loop is introduced into the input stage to charge VCIN to roughly near VREF. Then a correction loop further charges or discharges VCIN, substantially equalizing it with VREF. Dummy switches are introduced into the modulation stage to provide switching signals for setting up BFVC, and the power switches are disabled until the BFVC are set up successfully. A two channel single-ended class D amplifier with the above features is fabricated with 0.5 μm Bi-CMOS process. Road test and fast Fourier transform analysis indicate that there is no noticeable click and pop.

  14. Method and apparatus for providing pulse pile-up correction in charge quantizing radiation detection systems

    DOEpatents

    Britton, Jr., Charles L.; Wintenberg, Alan L.

    1993-01-01

    A radiation detection method and system for continuously correcting the quantization of detected charge during pulse pile-up conditions. Charge pulses from a radiation detector responsive to the energy of detected radiation events are converted to voltage pulses of predetermined shape whose peak amplitudes are proportional to the quantity of charge of each corresponding detected event by means of a charge-sensitive preamplifier. These peak amplitudes are sampled and stored sequentially in accordance with their respective times of occurrence. Based on the stored peak amplitudes and times of occurrence, a correction factor is generated which represents the fraction of a previous pulses influence on a preceding pulse peak amplitude. This correction factor is subtracted from the following pulse amplitude in a summing amplifier whose output then represents the corrected charge quantity measurement.

  15. Optical Amplifier for Space Applications

    NASA Technical Reports Server (NTRS)

    Fork, Richard L.; Cole, Spencer T.; Diffey, William M.; Gamble, Lisa J.

    1999-01-01

    We describe an open multipass optical amplifier designed to amplify a sampled region of an optical wavefront to kilowatt average power with low optical phase distortion. The overall goal is to amplify optical fields in a segmented, but phase coherent manner, so as to achieve high average power optical fields with high quality phase coherence over the large apertures needed for transmission of space solar power.

  16. Wavelength tunable alexandrite regenerative amplifier

    SciTech Connect

    Harter, D.J.; Bado, P.

    1988-11-01

    We describe a wavelength tunable alexandrite regenerative amplifier which is used to amplify nanosecond slices from a single-frequency cw dye laser or 50-ps pulses emitted by a diode laser to energies in the 10-mJ range. The amplified 5-ns slices generated by the cw-pumped line narrowed dye laser are Fourier transform limited. The 50-ps pulses emitted by a gain-switched diode laser are amplified by more than 10 orders of magnitude in a single stage.

  17. Reflex ring laser amplifier system

    DOEpatents

    Summers, Mark A.

    1985-01-01

    A laser pulse is injected into an unstable ring resonator-amplifier structure. Inside this resonator the laser pulse is amplified, spatially filtered and magnified. The laser pulse is recirculated in the resonator, being amplified, filtered and magnified on each pass. The magnification is chosen so that the beam passes through the amplifier in concentric non-overlapping regions similar to a single pass MOPA. After a number of passes around the ring resonator the laser pulse is spatially large enough to exit the ring resonator system by passing around an output mirror.

  18. Optical Amplifier for Space Applications

    NASA Technical Reports Server (NTRS)

    Fork, Richard L.; Cole, Spencer T.; Gamble, Lisa J.; Diffey, William M.; Keys, Andrew S.

    1999-01-01

    We describe an optical amplifier designed to amplify a spatially sampled component of an optical wavefront to kilowatt average power. The goal is means for implementing a strategy of spatially segmenting a large aperture wavefront, amplifying the individual segments, maintaining the phase coherence of the segments by active means, and imaging the resultant amplified coherent field. Applications of interest are the transmission of space solar power over multi-megameter distances, as to distant spacecraft, or to remote sites with no preexisting power grid.

  19. Charge transport improvement employing TiO2 nanotube arrays as front-side illuminated dye-sensitized solar cell photoanodes.

    PubMed

    Lamberti, Andrea; Sacco, Adriano; Bianco, Stefano; Manfredi, Diego; Cappelluti, Federica; Hernandez, Simelys; Quaglio, Marzia; Pirri, Candido Fabrizio

    2013-02-21

    TiO(2) nanotube (NT) arrays with different lengths were fabricated by anodic oxidation of Ti foil and free-standing NT membranes were detached by the metal substrate and bonded on the fluorine-doped tin oxide surface implementing an easy procedure. Morphology of the as-grown material and of the prepared photoanode was investigated by means of electron microscopy, deepening the investigation on the thermal treatment effect. Crystalline orientation and exposed surface area were studied by X-ray diffraction and Brunauer-Emmett-Teller measurements, showing suitable characteristics for the application in dye-sensitized solar cells (DSCs). DSCs were assembled employing a microfluidic housing system. The cell performances and the electron transport properties as a function of the tube length, before and after a TiCl(4) treatment, were characterized by I-V electrical measurements, incident photon-to-electron conversion efficiency, electrochemical impedance spectroscopy and open circuit voltage decay. Fitting the impedance spectra with an equivalent circuit, it was possible to obtain information on the electron diffusion properties into the TiO(2) nanotubes. A comparison with the charge transport properties evaluated in nanoparticle-based photoanodes witnesses a noteworthy increase of electron lifetime and diffusion length, yielding an overall power conversion efficiency up to 7.56%. PMID:22918400

  20. Enhanced charge-collection efficiencies and light scattering in dye-sensitized solar cells using oriented TiO2 nanotubes arrays.

    PubMed

    Zhu, Kai; Neale, Nathan R; Miedaner, Alexander; Frank, Arthur J

    2007-01-01

    We report on the microstructure and dynamics of electron transport and recombination in dye-sensitized solar cells (DSSCs) incorporating oriented TiO2 nanotube (NT) arrays. The morphology of the NT arrays, which were prepared from electrochemically anodized Ti foils, were characterized by scanning and transmission electron microscopies. The arrays were found to consist of closely packed NTs, several micrometers in length, with typical wall thicknesses and intertube spacings of 8-10 nm and pore diameters of about 30 nm. The calcined material was fully crystalline with individual NTs consisting of about 30 nm sized crystallites. The transport and recombination properties of the NT and nanoparticle (NP) films used in DSSCs were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopies. While both morphologies display comparable transport times, recombination was much slower in the NT films, indicating that the NT-based DSSCs have significantly higher charge-collection efficiencies than their NP-based counterparts. Dye molecules were shown to cover both the interior and exterior walls of the NTs. Analysis of photocurrent measurements indicates that the light-harvesting efficiencies of NT-based DSSCs were higher than those found for DSSCs incorporating NPs owing to stronger internal light-scattering effects. PMID:17212442

  1. Pulsed laser deposited porous nano-carpets of indium tin oxide and their use as charge collectors in core-shell structures for dye sensitized solar cells.

    PubMed

    Garvey, Timothy R; Farnum, Byron H; Lopez, Rene

    2015-02-14

    Porous In2O3:Sn (ITO) films resembling from brush carpets to open moss-like discrete nanostructures were grown by pulsed laser deposition under low to high background gas pressures, respectively. The charge transport properties of these mesoporous substrates were probed by pulsed laser photo-current and -voltage transient measurements in N719 dye sensitized devices. Although the cyclic voltammetry and dye adsorption measurements suggest a lower proportion of electro-active dye molecules for films deposited at the high-end background gas pressures, the transient measurements indicate similar electron transport rates within the films. Solar cell operation was achieved by the deposition of a conformal TiO2 shell layer by atomic layer deposition (ALD). Much of the device improvement was shown to be due to the TiO2 shell blocking the recombination of photoelectrons with the electrolyte as recombination lifetimes increased drastically from a few seconds in uncoated ITO to over 50 minutes in the ITO with a TiO2 shell layer. Additionally, an order of magnitude increase in the electron transport rate in ITO/TiO2 (core/shell) films was observed, giving the core-shell structure a superior ratio of recombination/transport times. PMID:25563519

  2. Self-amplifying mRNA vaccines.

    PubMed

    Brito, Luis A; Kommareddy, Sushma; Maione, Domenico; Uematsu, Yasushi; Giovani, Cinzia; Berlanda Scorza, Francesco; Otten, Gillis R; Yu, Dong; Mandl, Christian W; Mason, Peter W; Dormitzer, Philip R; Ulmer, Jeffrey B; Geall, Andrew J

    2015-01-01

    This chapter provides a brief introduction to nucleic acid-based vaccines and recent research in developing self-amplifying mRNA vaccines. These vaccines promise the flexibility of plasmid DNA vaccines with enhanced immunogenicity and safety. The key to realizing the full potential of these vaccines is efficient delivery of nucleic acid to the cytoplasm of a cell, where it can amplify and express the encoded antigenic protein. The hydrophilicity and strong net negative charge of RNA impedes cellular uptake. To overcome this limitation, electrostatic complexation with cationic lipids or polymers and physical delivery using electroporation or ballistic particles to improve cellular uptake has been evaluated. This chapter highlights the rapid progress made in using nonviral delivery systems for RNA-based vaccines. Initial preclinical testing of self-amplifying mRNA vaccines has shown nonviral delivery to be capable of producing potent and robust innate and adaptive immune responses in small animals and nonhuman primates. Historically, the prospect of developing mRNA vaccines was uncertain due to concerns of mRNA instability and the feasibility of large-scale manufacturing. Today, these issues are no longer perceived as barriers in the widespread implementation of the technology. Currently, nonamplifying mRNA vaccines are under investigation in human clinical trials and can be produced at a sufficient quantity and quality to meet regulatory requirements. If the encouraging preclinical data with self-amplifying mRNA vaccines are matched by equivalently positive immunogenicity, potency, and tolerability in human trials, this platform could establish nucleic acid vaccines as a versatile new tool for human immunization. PMID:25620012

  3. Laser amplifier developments at Mercury

    SciTech Connect

    Rose, E.A.; Brucker, J.P.; Honig, E.M.; McCown, A.W.; Romero, V.O.; York, G.W.

    1993-09-01

    Electron-beam pumped laser amplifiers have been modified to address the mission of krypton-fluoride excimer laser technology development. Methods are described for improving the performance and reliability of two pre-existing amplifiers at minimal cost and time. Preliminary performance data are presented to support the credibility of the approach.

  4. Suicide Risk: Amplifiers and Attenuators.

    ERIC Educational Resources Information Center

    Plutchik, Robert; Van Praag, Herman M.

    1994-01-01

    Attempts to integrate findings on correlates of suicide and violent risk in terms of a theory called a two-stage model of countervailing forces, which assumes that the strength of aggressive impulses is modified by amplifiers and attenuators. The vectorial interaction of amplifiers and attenuators creates an unstable equilibrium making prediction…

  5. Hybrid thin-film amplifier

    NASA Technical Reports Server (NTRS)

    Cleveland, G.

    1977-01-01

    Miniature amplifier for bioelectronic instrumentation consumes only about 100 mW and has frequency response flat to within 0.5 dB from 0.14 to 450 Hz. Device consists of five thin film substrates, which contain eight operational amplifiers and seven field-effect transistor dice.

  6. A novel research approach on the dynamic properties of photogenerated charge carriers at Ag{sub 2}S quantum-dots-sensitized TiO{sub 2} films by a frequency-modulated surface photovoltage technology

    SciTech Connect

    Zhang, Yu; Zhang, Wei; Xie, Tengfeng; Wang, Dejun; Song, Xi-Ming

    2013-09-01

    Graphical abstract: The changed SPV with chopping frequencies indicate the separation speeds of photogenerated charge carriers in different films. - Highlights: • Ag{sub 2}S-sensitized TiO{sub 2} films show good photoelectric responses in visible-light region. • Frequency-modulated SPV give dynamic information and evidence of Ag{sub 2}S QDSSCs’ performance. • Frequency-modulated SPV can supply complementary information in the study of Ag{sub 2}S ODSSCs. - Abstract: Ag{sub 2}S quantum-dots-sensitized TiO{sub 2} films with different amount of Ag{sub 2}S were fabricated by a successive ionic layer adsorption and reaction (SILAR) method. The separation and transport of photogenerated charge carriers at different spectral regions were studied by the frequency-modulated surface photovoltage technology. Some novel dynamic information of photogenerated charge carriers in a wide spectral range is found. The results indicate that the rate and direction of separation (diffusion) for photogenerated charge carriers are closely related to the performance of quantum-dots-sensitized solar cells (QDSSCs) based on the Ag{sub 2}S/TiO{sub 2} nano-structure.

  7. MOSFET's for Cryogenic Amplifiers

    NASA Technical Reports Server (NTRS)

    Dehaye, R.; Ventrice, C. A.

    1987-01-01

    Study seeks ways to build transistors that function effectively at liquid-helium temperatures. Report discusses physics of metaloxide/semiconductor field-effect transistors (MOSFET's) and performances of these devices at cryogenic temperatures. MOSFET's useful in highly sensitive cryogenic preamplifiers for infrared astronomy.

  8. Monitoring the intramolecular charge transfer process in the Z907 solar cell sensitizer: a transient Vis and IR spectroscopy and ab initio investigation.

    PubMed

    Azzaroli, Nicolò; Lobello, Maria Grazia; Lapini, Andrea; Iagatti, Alessandro; Bussotti, Laura; Di Donato, Mariangela; Calogero, Giuseppe; Pastore, Mariachiara; De Angelis, Filippo; Foggi, Paolo

    2015-09-01

    We have analyzed the excited state dynamics of the heteroleptic [(NCS)2Ru(bpy-(COOH)2)(bpy-(C6H13)2)] Z907 solar cell sensitizer in solution and when adsorbed onto thin TiO2 films, by combining transient visible and infrared (IR) spectroscopies with ab initio Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) calculations. Upon excitation with ultra-short pulses in ethanol and dimethyl-sulphoxide solutions, the visible spectra show the appearance of a positive signal around 650 nm, within the instrumental time resolution (<100 fs), which in ethanol undergoes a red-shift in about 20 ps. Measurements in the IR indicate that, upon excitation, both the CN and CO marker bands, associated with the NCS and COOH groups, downshift in frequency, in response to intramolecular ligand + metal (Ru-NCS) to ligand' (bpy-COOH2) charge transfer (LML'CT). Vibrational cooling is observed in both solvents; in ethanol it is overtaken by the hydrogen bond dynamics. On the basis of DFT/TDDFT calculations, explicitly modeling the interaction of the NCS and COOH groups with solvent (ethanol) molecules, we rationalize the observed IR and visible spectral evolution as arising from the change in the hydrogen-bond network, which accompanies the transition to the lowest-energy triplet state. This interpretation provides a consistent explanation of what is also observed in the transient visible spectra. Transient IR measurements repeated for molecules adsorbed on TiO2 and ZrO2 films, allow us to identify the structural changes signaling the dye triplet excited state formation and evidence multiexponential electron injection rates into the semiconductor TiO2 film. PMID:26220307

  9. Fast terahertz imaging using a quantum cascade amplifier

    SciTech Connect

    Ren, Yuan Wallis, Robert; Jessop, David Stephen; Degl'Innocenti, Riccardo; Klimont, Adam; Beere, Harvey E.; Ritchie, David A.

    2015-07-06

    A terahertz (THz) imaging scheme based on the effect of self-mixing in a 2.9 THz quantum cascade (QC) amplifier has been demonstrated. By coupling an antireflective-coated silicon lens to the facet of a QC laser, with no external optical feedback, the laser mirror losses are enhanced to fully suppress lasing action, creating a THz QC amplifier. The addition of reflection from an external target to the amplifier creates enough optical feedback to initiate lasing action and the resulting emission enhances photon-assisted transport, which in turn reduces the voltage across the device. At the peak gain point, the maximum photon density coupled back leads to a prominent self-mixing effect in the QC amplifier, leading to a high sensitivity, with a signal to noise ratio up to 55 dB, along with a fast data acquisition speed of 20 000 points per second.

  10. Final amplifier design and mercury

    SciTech Connect

    Rose, E.A.; Hanson, D.E.

    1991-01-01

    The final amplifier for the Mercury KrF excimer facility is being designed. The design exercise involves extensive modeling to predict amplifier performance. Models of the pulsed-power system, including a Child-Langmuir diode with closure, electron-beam energy deposition, KrF laser kinetics, amplified spontaneous emission (ASE), a time-dependent laser extraction in the presence of ASE are presented as a design package. The design exercise indicates that the energy objective of Phase I -- 100 joules -- will be met.

  11. Final amplifier design and mercury

    SciTech Connect

    Rose, E.A.; Hanson, D.E.

    1991-12-31

    The final amplifier for the Mercury KrF excimer facility is being designed. The design exercise involves extensive modeling to predict amplifier performance. Models of the pulsed-power system, including a Child-Langmuir diode with closure, electron-beam energy deposition, KrF laser kinetics, amplified spontaneous emission (ASE), a time-dependent laser extraction in the presence of ASE are presented as a design package. The design exercise indicates that the energy objective of Phase I -- 100 joules -- will be met.

  12. Enhanced charge collection and reduced recombination of CdS /TiO2 quantum-dots sensitized solar cells in the presence of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lee, Wonjoo; Lee, Jungwoo; Lee, Sangjin; Yi, Whikun; Han, Sung-Hwan; Cho, Byung Won

    2008-04-01

    This paper reports the modification of CdS /TiO2 quantum-dot sensitized solar cells by using single-walled carbon nanotubes (SWCNTs) on indium-doped tin oxide (ITO) electrodes. The presence of the SWCNT layers on an ITO electrode increased the short-circuit current under the irradiation condition and also reduced the charge recombination process under the dark condition. The power conversion efficiency of CdS /TiO2 on ITO increased 50.0% in the presence of SWCNTs due to the improved charge-collecting efficiency and reduced recombination.

  13. Measuring momentum for charged particle tomography

    DOEpatents

    Morris, Christopher; Fraser, Andrew Mcleod; Schultz, Larry Joe; Borozdin, Konstantin N.; Klimenko, Alexei Vasilievich; Sossong, Michael James; Blanpied, Gary

    2010-11-23

    Methods, apparatus and systems for detecting charged particles and obtaining tomography of a volume by measuring charged particles including measuring the momentum of a charged particle passing through a charged particle detector. Sets of position sensitive detectors measure scattering of the charged particle. The position sensitive detectors having sufficient mass to cause the charged particle passing through the position sensitive detectors to scatter in the position sensitive detectors. A controller can be adapted and arranged to receive scattering measurements of the charged particle from the charged particle detector, determine at least one trajectory of the charged particle from the measured scattering; and determine at least one momentum measurement of the charged particle from the at least one trajectory. The charged particle can be a cosmic ray-produced charged particle, such as a cosmic ray-produced muon. The position sensitive detectors can be drift cells, such as gas-filled drift tubes.

  14. Rain Drop Charge Sensor

    NASA Astrophysics Data System (ADS)

    S, Sreekanth T.

    begin{center} Large Large Rain Drop Charge Sensor Sreekanth T S*, Suby Symon*, G. Mohan Kumar (1) , S. Murali Das (2) *Atmospheric Sciences Division, Centre for Earth Science Studies, Thiruvananthapuram 695011 (1) D-330, Swathi Nagar, West Fort, Thiruvananthapuram 695023 (2) Kavyam, Manacaud, Thiruvananthapuram 695009 begin{center} ABSTRACT To study the inter-relations with precipitation electricity and precipitation microphysical parameters a rain drop charge sensor was designed and developed at CESS Electronics & Instrumentation Laboratory. Simultaneous measurement of electric charge and fall speed of rain drops could be done using this charge sensor. A cylindrical metal tube (sensor tube) of 30 cm length is placed inside another thick metal cover opened at top and bottom for electromagnetic shielding. Mouth of the sensor tube is exposed and bottom part is covered with metal net in the shielding cover. The instrument is designed in such a way that rain drops can pass only through unhindered inside the sensor tube. When electrically charged rain drops pass through the sensor tube, it is charged to the same magnitude of drop charge but with opposite polarity. The sensor tube is electrically connected the inverted input of a current to voltage converter operational amplifier using op-amp AD549. Since the sensor is electrically connected to the virtual ground of the op-amp, the charge flows to the ground and the generated current is converted to amplified voltage. This output voltage is recorded using a high frequency (1kHz) voltage recorder. From the recorded pulse, charge magnitude, polarity and fall speed of rain drop are calculated. From the fall speed drop diameter also can be calculated. The prototype is now under test running at CESS campus. As the magnitude of charge in rain drops is an indication of accumulated charge in clouds in lightning, this instrument has potential application in the field of risk and disaster management. By knowing the charge

  15. Design and simulation of a gyroklystron amplifier

    SciTech Connect

    Chauhan, M. S. Swati, M. V.; Jain, P. K.

    2015-03-15

    In the present paper, a design methodology of the gyroklystron amplifier has been described and subsequently used for the design of a typically selected 200 kW, Ka-band, four-cavity gyroklystron amplifier. This conceptual device design has been validated through the 3D particle-in-cell (PIC) simulation and nonlinear analysis. Commercially available PIC simulation code “MAGIC” has been used for the electromagnetic study at the different location of the device RF interaction structure for the beam-absent case, i.e., eigenmode study as well as for the electron beam and RF wave interaction behaviour study in the beam present case of the gyroklystron. In addition, a practical problem of misalignment of the RF cavities with drift tubes within the tube has been also investigated and its effect on device performance studied. The analytical and simulation results confirmed the validity of the gyroklystron device design. The PIC simulation results of the present gyroklystron produced a stable RF output power of ∼218 kW for 0% velocity spread at 35 GHz, with ∼45 dB gain, 37% efficiency, and a bandwidth of 0.3% for a 70 kV, 8.2 A gyrating electron beam. The simulated values of RF output power have been found in agreement with the nonlinear analysis results within ∼5%. Further, the PIC simulation has been extended to study a practical problem of misalignment of the cavities axis and drift tube axis of the gyroklystron amplifier and found that the RF output power is more sensitive to misalignments in comparison to the device bandwidth. The present paper, gyroklystron device design, nonlinear analysis, and 3D PIC simulation using commercially available code had been systematically described would be of use to the high-power gyro-amplifier tube designers and research scientists.

  16. Design and simulation of a gyroklystron amplifier

    NASA Astrophysics Data System (ADS)

    Chauhan, M. S.; Swati, M. V.; Jain, P. K.

    2015-03-01

    In the present paper, a design methodology of the gyroklystron amplifier has been described and subsequently used for the design of a typically selected 200 kW, Ka-band, four-cavity gyroklystron amplifier. This conceptual device design has been validated through the 3D particle-in-cell (PIC) simulation and nonlinear analysis. Commercially available PIC simulation code "MAGIC" has been used for the electromagnetic study at the different location of the device RF interaction structure for the beam-absent case, i.e., eigenmode study as well as for the electron beam and RF wave interaction behaviour study in the beam present case of the gyroklystron. In addition, a practical problem of misalignment of the RF cavities with drift tubes within the tube has been also investigated and its effect on device performance studied. The analytical and simulation results confirmed the validity of the gyroklystron device design. The PIC simulation results of the present gyroklystron produced a stable RF output power of ˜218 kW for 0% velocity spread at 35 GHz, with ˜45 dB gain, 37% efficiency, and a bandwidth of 0.3% for a 70 kV, 8.2 A gyrating electron beam. The simulated values of RF output power have been found in agreement with the nonlinear analysis results within ˜5%. Further, the PIC simulation has been extended to study a practical problem of misalignment of the cavities axis and drift tube axis of the gyroklystron amplifier and found that the RF output power is more sensitive to misalignments in comparison to the device bandwidth. The present paper, gyroklystron device design, nonlinear analysis, and 3D PIC simulation using commercially available code had been systematically described would be of use to the high-power gyro-amplifier tube designers and research scientists.

  17. Characterization of SLUG microwave amplifiers

    NASA Astrophysics Data System (ADS)

    Hoi, I.-C.; Zhu, S.; Thorbeck, T.; McDermott, R.; Mutus, J.; Jeffrey, E.; Barends, R.; Chen, Y.; Roushan, P.; Fowler, A.; Sank, D.; White, T.; Campbell, B.; Chen, Z.; Chiaro, B.; Dunsworth, A.; Kelly, J.; Megrant, A.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Vainsencher, A.; Wenner, J.; Martinis, J. M.

    2015-03-01

    With the rapid growth of superconducting circuits quantum technology, a near quantum-limited amplifier at GHz frequency is needed to enable high fidelity measurements. We describe such an amplifier, the SQUID based, superconducting low inductance undulatory galvanometer (SLUG) amplifier. We measure the full scattering matrix of the SLUG. In particular, we measure both forward and reverse gain, as well as reflection. We see 15dB forward gain with added noise from one quanta to several quanta. The -1 dB compression point is around -95 dBm, about two orders of magnitude higher than that of typical Josephson parametric amplifiers. With these properties, SLUG is well suited for the high fidelity, simultaneous multiplexed readout of superconducting qubits.

  18. Amplifier arrays for CMB polarization

    NASA Technical Reports Server (NTRS)

    Gaier, Todd; Lawrence, Charles R.; Seiffert, Michael D.; Wells, Mary M.; Kangaslahti, Pekka; Dawson, Douglas

    2003-01-01

    Cryogenic low noise amplifier technology has been successfully used in the study of the cosmic microwave background (CMB). MMIC (Monolithic Millimeter wave Integrated Circuit) technology makes the mass production of coherent detection receivers feasible.

  19. New Packaging for Amplifier Slabs

    SciTech Connect

    Riley, M.; Thorsness, C.; Suratwala, T.; Steele, R.; Rogowski, G.

    2015-03-18

    The following memo provides a discussion and detailed procedure for a new finished amplifier slab shipping and storage container. The new package is designed to maintain an environment of <5% RH to minimize weathering.

  20. Dye laser traveling wave amplifier

    NASA Technical Reports Server (NTRS)

    Davidson, F.; Hohman, J.

    1984-01-01

    A flashlamp pumped dye laser suitable for use as a single stage amplifier is described. Particular emphasis is placed on the efforts to increase output pulse energy and improve the temporal profile of the injected pulse. By using high power thin film polarizers, output energies reach from 4 to 45 mJ. Various dispersive elements are used to develop an amplified pulse with an extremely clean temporal profile.

  1. Membrane supported liquid-liquid-liquid microextraction combined with field-amplified sample injection CE-UV for high-sensitivity analysis of six cardiovascular drugs in human urine sample.

    PubMed

    Zhou, Xiaoqing; He, Man; Chen, Beibei; Yang, Qing; Hu, Bin

    2016-05-01

    An effective dual preconcentration method involving off-line membrane supported liquid-liquid-liquid microextraction (MS-LLLME) and on-line field-amplified sample injection (FASI) was proposed for the extraction of six cardiovascular drugs, including mexiletine, xylocaine, propafenone, propranolol, metoprolol, and carvedilol from aqueous solution prior to CE-UV. In MS-LLLME, the analytes were extracted from 9 mL sample solution into toluene, and then back extracted into a drop of acceptor phase of 10 μL 20 mmol/L acetic acid. After that, the acceptor phase was directly introduced into CE for FASI without any modification. In FASI process, water plug was hydrodynamically injected (50 mbar, 3 s) into the capillary prior to sample injection (+6 kV, 18 s). Six target analytes were separated in less than 10 min at 25°C with a BGE consisting of 70 mmol/L Tris-H3 PO4 (pH 2.2) containing 10% v/v methanol. Under the optimized conditions, LODs obtained by the proposed MS-LLLME-FASI-CE-UV method were in the range of 0.02-0.82 μg/L (based on S/N = 3) with enrichment factors of 546- to 7300-fold for the target analytes. The RSDs of the developed method were in the range of 6.7-12.9% (n = 7). Good linearity (R(2) = 0.9928-0.9997) was obtained in concentration range of 0.1-100 μg/L for mexiletine and propranolol, 0.2-100 μg/L for xylocaine and metoprolol, 0.5-100 μg/L for propafenone and 2.0-100 μg/L for carvedilol, respectively. The developed method was successfully applied for real-time determination of metoprolol in human urine samples within 26 h after uptake. PMID:26763094

  2. RF Single Electron Transistor Readout Amplifiers for Superconducting Astronomical Detectors for X-Ray to Sub-mm Wavelengths

    NASA Technical Reports Server (NTRS)

    Stevenson, Thomas; Aassime, Abdelhanin; Delsing, Per; Frunzio, Luigi; Li, Li-Qun; Prober, Daniel; Schoelkopf, Robert; Segall, Ken; Wilson, Chris; Stahle, Carl

    2000-01-01

    We report progress on using a new type of amplifier, the Radio-Frequency Single-Electron Transistor (RF-SET), to develop multi-channel sensor readout systems for fast and sensitive readout of high impedance cryogenic photodetectors such as Superconducting Tunnel Junctions and Single Quasiparticle Photon Counters. Although cryogenic, these detectors are desirable because of capabilities not other-wise attainable. However, high impedances and low output levels make low-noise, high-speed readouts challenging, and large format arrays would be facilitated by compact, low-power, on-chip integrated amplifiers. Well-suited for this application are RF-SETs, very high performance electrometers which use an rf readout technique to provide 100 MHz bandwidth. Small size, low power, and cryogenic operation allow direct integration with detectors, and using multiple rf carrier frequencies permits simultaneous readout of 20-50 amplifiers with a common electrical connection. We describe both the first 2-channel demonstration of this wavelength division multiplexing technique for RF-SETs, and Charge-Locked-Loop operation with 100 kHz of closed-loop bandwidth.

  3. Single Ion Quantum Lock-In Amplifier

    NASA Astrophysics Data System (ADS)

    Kotler, Shlomi; Akerman, Nitzan; Glickman, Yinnon; Keselman, Anna; Ozeri, Roee

    2011-05-01

    Invented by Dicke, the lock-in measurement is a phase-sensitive detection scheme that can extract a signal with a known carrier frequency from an extremely noisy environment. Here we report on the implementation of a quantum analog to the classical lock- in amplifier. All the lock-in operations: modulation, detection and mixing, are performed via the application of non-commuting quantum operators on the electronic spin state of a single trapped Sr+ ion. We increase its sensitivity to external fields while extending phase coherence by three orders of magnitude, to more than one second. With this technique we measure magnetic fields with sensitivity of 25 pT /√{ Hz } , and light shifts with an uncertainty below 140 mHz after 1320 seconds of averaging. These sensitivities are limited by quantum projection noise and, to our knowledge, are more than two orders of magnitude better than with other single-spin probe technologies. As a first application we perform light shift spectroscopy of a narrow optical quadruple transition. We remark that the quantum lock-in technique is generic and can potentially enhance the sensitivity of any quantum sensor. (http://arxiv.org/abs/1101.4885)

  4. Low-Noise Band-Pass Amplifier

    NASA Technical Reports Server (NTRS)

    Kleinberg, L.

    1982-01-01

    Circuit uses standard components to overcome common limitation of JFET amplifiers. Low-noise band-pass amplifier employs JFET and operational amplifier. High gain and band-pass characteristics are achieved with suitable choice of resistances and capacitances. Circuit should find use as low-noise amplifier, for example as first stage instrumentation systems.

  5. Reflex ring laser amplifier system

    DOEpatents

    Summers, M.A.

    1983-08-31

    The invention is a method and apparatus for providing a reflex ring laser system for amplifying an input laser pulse. The invention is particularly useful in laser fusion experiments where efficient production of high-energy and high power laser pulses is required. The invention comprises a large aperture laser amplifier in an unstable ring resonator which includes a combination spatial filter and beam expander having a magnification greater than unity. An input pulse is injected into the resonator, e.g., through an aperture in an input mirror. The injected pulse passes through the amplifier and spatial filter/expander components on each pass around the ring. The unstable resonator is designed to permit only a predetermined number of passes before the amplified pulse exits the resonator. On the first pass through the amplifier, the beam fills only a small central region of the gain medium. On each successive pass, the beam has been expanded to fill the next concentric non-overlapping region of the gain medium.

  6. A position sensitive microchannel photomultiplier for ultraviolet space astronomy

    NASA Technical Reports Server (NTRS)

    Lampton, M.; Siegmund, O. H. W.; Bixler, J.; Bowyer, S.

    1986-01-01

    The 25-mm microchannel-plate, position-sensitive UV astronomy photomultiplier tube presented is intended for the EOM-1 Spacelab Mission's FAUST payload and conducts wide-field imaging surveys in the VUV over the 1400-1800-A range. The sealed detector encompasses a CsI photocathode deposited on the inner surface of a MgF2 window, a stack of microchannel plates, and a wedge-and-strip two-dimensional position-sensing anode. Since the wedge-and-strip principle requires only three anode signals, flight electronics can be reduced to three charge amplifiers and three analog-to-digital converters.

  7. Implementation of a preamplifier-amplifier system for radiation detectors used in Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Velásquez, A. A.; Arroyave, M.

    2014-01-01

    We report the assembly and testing of a preamplification and amplification system for pulses produced by gaseous radiation detectors commonly used in Mössbauer spectroscopy. The system is composed by a pair of commercial integrated circuits A203 and A206, which operate as charge sensitive preamplifier-shaping amplifier and linear amplifier-low level discriminator, respectively. The integrated circuits were interconnected in the unipolar output mode and placed inside a metallic shielding, which prevents noise amplification for a suitable signal-noise ratio. The system was tested by irradiating a proportional counter LND-45431 with characteristic X rays of 6.3 keV and gamma rays of 14.4 keV emitted by a Mössbauer radioactive source of 57Co (Rh). Unipolar pulses with Gaussian profile were obtained at the output of the linear amplifier, whose amplitudes were close to 0.4 V for 6.3 keV X rays and 1.4 V for 14.4 keV gamma rays. Pulse height spectra showed that the system allows a satisfactory identification of the X-rays and gamma rays emitted by the 57Co source, giving the possibility to make a good selection of the 14.4 keV peak for having a suitable signal-noise ratio in the Mössbauer spectra. Absorption percentages of 14 % were found by taking the Mössbauer spectra of a natural iron absorber. The assembly and tests of the system are presented through this paper.

  8. Optical amplifiers for coherent lidar

    NASA Technical Reports Server (NTRS)

    Fork, Richard

    1996-01-01

    We examine application of optical amplification to coherent lidar for the case of a weak return signal (a number of quanta of the return optical field close to unity). We consider the option that has been explored to date, namely, incorporation of an optical amplifier operated in a linear manner located after reception of the signal and immediately prior to heterodyning and photodetection. We also consider alternative strategies where the coherent interaction, the nonlinear processes, and the amplification are not necessarily constrained to occur in the manner investigated to date. We include the complications that occur because of mechanisms that occur at the level of a few, or one, quantum excitation. Two factors combine in the work to date that limit the value of the approach. These are: (1) the weak signal tends to require operation of the amplifier in the linear regime where the important advantages of nonlinear optical processing are not accessed, (2) the linear optical amplifier has a -3dB noise figure (SN(out)/SN(in)) that necessarily degrades the signal. Some improvement is gained because the gain provided by the optical amplifier can be used to overcome losses in the heterodyned process and photodetection. The result, however, is that introduction of an optical amplifier in a well optimized coherent lidar system results in, at best, a modest improvement in signal to noise. Some improvement may also be realized on incorporating more optical components in a coherent lidar system for purely practical reasons. For example, more compact, lighter weight, components, more robust alignment, or more rapid processing may be gained. We further find that there remain a number of potentially valuable, but unexplored options offered both by the rapidly expanding base of optical technology and the recent investigation of novel nonlinear coherent interference phenomena occurring at the single quantum excitation level. Key findings are: (1) insertion of linear optical

  9. Laser system using regenerative amplifier

    DOEpatents

    Emmett, J.L.

    1980-03-04

    High energy laser system is disclosed using a regenerative amplifier, which relaxes all constraints on laser components other than the intrinsic damage level of matter, so as to enable use of available laser system components. This can be accomplished by use of segmented components, spatial filters, at least one amplifier using solid state or gaseous media, and separated reflector members providing a long round trip time through the regenerative cavity, thereby allowing slower switching and adequate time to clear the spatial filters, etc. The laser system simplifies component requirements and reduces component cost while providing high energy output. 10 figs.

  10. Laser system using regenerative amplifier

    DOEpatents

    Emmett, John L. [Pleasanton, CA

    1980-03-04

    High energy laser system using a regenerative amplifier, which relaxes all constraints on laser components other than the intrinsic damage level of matter, so as to enable use of available laser system components. This can be accomplished by use of segmented components, spatial filters, at least one amplifier using solid state or gaseous media, and separated reflector members providing a long round trip time through the regenerative cavity, thereby allowing slower switching and adequate time to clear the spatial filters, etc. The laser system simplifies component requirements and reduces component cost while providing high energy output.

  11. Amplifier-Discriminator-Multiplexor card

    SciTech Connect

    Graupman, D.

    1986-02-01

    The Amplifier-Discriminator-Multiplexor (ADM) card described was designed for the External Muon Identifier at the 15 ft Bubble Chamber. The general scheme of the data readout of the External Muon Identifier is based on the use of a master clock. The ADM card serves to amplify the signals from the proportional tubes, discriminate them, latch the signals in parallel into a shift register. The data are then shifted out serially to the Time Digitizing System, using the master clock. The shift registers are loaded, and the latches are reset every sixteen cycles of the master clock. (LEW)

  12. Enzyme-free and sensitive electrochemical determination of the FLT3 gene based on a dual signal amplified strategy: Controlled nanomaterial multilayers and a target-catalyzed hairpin assembly.

    PubMed

    Sun, Yingying; Ren, Qunxiang; Liu, Bo; Qin, Yan; Zhao, Shuang

    2016-04-15

    An isothermal, enzyme-free and sensitive electrochemical DNA sensor was developed for the detection of the FLT3 gene in acute myeloid leukemia (AML). First, aminated multi-walled carbon nanotubes (AMWNTs) and gold nanoparticles (AuNPs) were alternately self-assembled on a gold electrode using a layer-by-layer strategy. Then, the hairpin DNA probe 1 (H1), with a thiol group at the 3' end and a ferrocenyl moiety (Fc) at the 5' end, was immobilized on the AMWNTs/AuNPs multilayer films through Au-S bonding. When the target DNA (TD) appeared, it hybridized with and opened the hairpin structure of H1, and Fc was forced away from the electrode surface, leading to a significant decrease in the current peak of square wave voltammetry. Subsequently, the hairpin DNA probe 2 (H2) bound to H1, freeing the TD to trigger another reaction cycle. The combination of this target-catalyzed hairpin assembly and the LBL assembly of nanomaterials achieved a detection limit of 0.1 pM with a wide linear range of 0.1-1000 pM. The sensor discriminated between mismatched DNA and the target DNA with high selectivity. This dual signal amplification strategy is relatively simple and inexpensive because it does not need any enzymes or sophisticated equipment and successfully assayed the FLT3 gene from real samples. PMID:26584077

  13. The School as an Amplifier.

    ERIC Educational Resources Information Center

    Vincent, William S.

    1966-01-01

    This paper attempts to show that adaptation of mathematics to the input-output model of the school can provide powerful assistance in the measurement and analysis of school quality and its determinants. The mathematical relationship described here relates an educational model to the field of electronics. More specifically, the amplifier, a device…

  14. Dye laser traveling wave amplifier

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1983-01-01

    A flash lamp pumped dye laser suitable for use as an amplifier stage was developed. The desired output laser pulses are of nanosecond duration, tunable in center frequency, and of good optical quality. Its usefulness as a laser oscillator is emphasized, because it constitutes a compact, relatively efficient source of tunable dye laser light.

  15. Electrometer Amplifier With Overload Protection

    NASA Technical Reports Server (NTRS)

    Woeller, F. H.; Alexander, R.

    1986-01-01

    Circuit features low noise, input offset, and high linearity. Input preamplifier includes input-overload protection and nulling circuit to subtract dc offset from output. Prototype dc amplifier designed for use with ion detector has features desirable in general laboratory and field instrumentation.

  16. Stroke amplifier for deformable mirrors

    PubMed Central

    Webb, Robert H.; Albanese, Marc J.; Zhou, Yaopeng; Bifano, Thomas; Burns, Stephen A.

    2010-01-01

    We demonstrate a simple optical configuration that amplifies the usable stroke of a deformable mirror. By arranging for the wavefront to traverse the deformable mirror more than once, we correct it more than once. The experimental implementation of the idea demonstrates a doubling of 2.0 and 2.04 by two different means. PMID:15495423

  17. Cryogenic MMIC Low Noise Amplifiers

    NASA Technical Reports Server (NTRS)

    Weinreb, S.; Gaier, T.; Fernandez, J.; Erickson, N.; Wielgus, J.

    2000-01-01

    Monolithic (MMIC) and discrete transistor (MIC) low noise amplifiers are compared on the basis of performance, cost, and reliability. The need for cryogenic LNA's for future large microwave arrays for radio astronomy is briefly discussed and data is presented on a prototype LNA for the 1 to 10 GZH range along with a very wideband LNA for the 1 to 60 GHz range.

  18. Nuclear magnetic resonance experiments with dc SQUID amplifiers

    SciTech Connect

    Heaney, M.B. . Dept. of Physics Lawrence Berkeley Lab., CA )

    1990-11-01

    The development and fabrication of dc SQUIDs (Superconducting QUantum Interference Devices) with Nb/Al{sub 2}O{sub 3}/Nb Josephson junctions is described. A theory of the dc SQUID as a radio-frequency amplifier is presented, with an optimization strategy that accounts for the loading and noise contributions of the postamplifier and maximizes the signal-to-noise ratio of the total system. The high sensitivity of the dc SQUID is extended to high field NMR. A dc SQUID is used as a tuned radio-frequency amplifier to detect pulsed nuclear magnetic resonance at 32 MHz from a metal film in a 3.5 Tesla static field. A total system noise temperature of 11 K has been achieved, at a bath temperature of 4.2 K. The minimum number of nuclear Bohr magnetons observable from a free precession signal after a single pulse is about 2 {times} 10{sup 17} in a bandwidth of 25 kHz. In a separate experiment, a dc SQUID is used as a rf amplifier in a NQR experiment to observe a new resonance response mechanism. The net electric polarization of a NaClO{sub 3} crystal due to the precessing electric quadrupole moments of the Cl nuclei is detected at 30 MHz. The sensitivity of NMR and NQR spectrometers using dc SQUID amplifiers is compared to the sensitivity of spectrometers using conventional rf amplifiers. A SQUID-based spectrometer has a voltage sensitivity which is comparable to the best achieved by a FET-based spectrometer, at these temperatures and operating frequencies.

  19. Designing nanostructured one-dimensional TiO2 nanotube and TiO2 nanoparticle multilayer composite film as photoanode in dye-sensitized solar cells to increase the charge collection efficiency

    NASA Astrophysics Data System (ADS)

    Akilavasan, Jeganathan; Al-Jassim, Maufick; Bandara, Jayasundera

    2015-01-01

    A photoanode consisting of hydrothermally synthesized TiO2 nanotubes (TNT) and TiO2 nanoparticles (TNP) was designed for efficient charge collection in dye-sensitized solar cells. TNT and TNP films were fabricated on a conductive glass substrate by using electrophoretic deposition and doctor-blade methods, respectively. The TNP, TNT, and TNT/TNP bi-layer electrodes exhibit solar cell efficiencies of 5.3, 7.4, and 9.2%, respectively. Solar cell performance results indicate a higher short-circuit current density (Jsc) for the TNT/TNP bi-layer electrode when compared to a TNT or TNP electrode alone. The open-circuit voltages (Voc) of TNT/TNP and TNT electrodes are comparable while the Voc of TNP electrode is inferior to that of the TNT/TNP electrode. Fill factors of TNT/TNP, TNT, and TNP electrodes also exhibit similar behaviors. The enhanced efficiency of the TNT/TNP bi-layer electrode is found to be mainly due to the enhancement of charge collection efficiency, which is confirmed by the charge transport parameters measured by electrochemical impedance spectroscopy (EIS). EIS analyses also revealed that the TNT/TNP incurs smaller charge transport resistances and longer electron life times when compared to those of TNT or TNP electrodes alone. It was demonstrated that the TNT/TNP bi-layer electrode can possess the advantages of both rapid electron transport rate and a high light scattering effect.

  20. High efficiency x-band TWT amplifiers

    SciTech Connect

    Naqvi, S.; Kerslick, G.S.; Nation, J.A.; Wang, Q.

    1997-12-31

    The authors report on a research program to increase the efficiency of relativistic traveling wave amplifiers to > 50%. The two stage amplifier consists of a bunching periodic structure with phase velocity and a decelerating section with phase velocity significantly lower than the beam velocity. The position of the decelerating stage with respect to the bunching stage is chosen such that the narrowest bunches are sustained in the decelerating field for the longest possible time before significant debunching occurs. Two schemes are under investigation. In the first scheme, a resistive sever is placed between the two stages to suppress temporal phenomena. In the second scheme, the bunching and decelerating stages merge into each other by a gradual change in the iris radius over a wavelength. An absorbing section in this case is placed before the start of the bunching stage. A Coaxial extraction geometry is used in both schemes. Efficiencies obtained from MAGIC simulations are comparable to those obtained in high efficiency klystrons (50--50%) but carry the important advantage of broad-bandwidth, low sensitivity on dimensions, low surface fields, and simplicity of design.

  1. Integrating and amplifying signal from riboswitch biosensors.

    PubMed

    Goodson, Michael S; Harbaugh, Svetlana V; Chushak, Yaroslav G; Kelley-Loughnane, Nancy

    2015-01-01

    Biosensors offer a built-in energy supply and inherent sensing machinery that when exploited correctly may surpass traditional sensors. However, biosensor systems have been hindered by a narrow range of ligand detection capabilities, a relatively low signal output, and their inability to integrate multiple signals. Integration of signals could increase the specificity of the sensor and enable detection of a combination of ligands that may indicate environmental or developmental processes when detected together. Amplifying biosensor signal output will increase detector sensitivity and detection range. Riboswitches offer the potential to widen the diversity of ligands that may be detected, and advances in synthetic biology are illuminating myriad possibilities in signal processing using an orthogonal parts-based engineering approach. In this chapter, we describe the design, building, and testing of a riboswitch-based Boolean logic AND gate in bacteria, where an output requires the activation of two riboswitches, and the biological circuitry required to amplify the output of the AND gate using natural extracellular bacterial communication signals to "wire" cells together. PMID:25605381

  2. Broadband Characterization of a 100 to 180 GHz Amplifier

    NASA Technical Reports Server (NTRS)

    Kangaslahti, Pekka; Deal, W. R.; Mei, X. B.; Lai, R.

    2007-01-01

    Atmospheric science and weather forecasting require measurements of the temperature and humidity vs. altitude. These sounding measurements are obtained at frequencies close to the resonance frequencies of oxygen (118 GHz) and water (183 GHz) molecules. We have characterized a broadband amplifier that will increase the sensitivity of sounding and other instruments at these frequencies. This study demonstrated for the first t1me continuous low noise amplification from 100 to 180 GHz. The measured InP monolithic millimeter-wave Integrated circuit (MMIC) amplifier had more than 18 dB of gain from 100 to 180 GHz and 15 dB of gain up to 220 GHz. This is the widest bandwidth low noise amplifier result at these frequencies to date. The circuit was fabricated in Northrop Grumman Corporation 35 nm InP high electron mobility transistor (HEMT).

  3. Josephson traveling-wave parametric amplifier for superconducting qubit readout

    NASA Astrophysics Data System (ADS)

    Macklin, Chris; Slichter, D. H.; Yaakobi, O.; Friedland, L.; Bolkhovsky, V.; Braje, D. A.; Fitch, G.; Oliver, W. D.; Siddiqi, I.

    2014-03-01

    Superconducting parametric amplifiers (paramps) have successfully demonstrated near quantum limited sensitivity, enabling single-shot qubit readout, feedback, and state tracking. However, these amplifiers are commonly limited to narrow bandwidth and modest dynamic range, and most require microwave circulators to separate input and output modes. These limitations stem from the use of a resonant non-linearity to achieve mixing between a signal and pump mode. Our traveling-wave parametric amplifier (TWPA) is based on a superconducting nonlinear Josephson junction transmission line, thereby inherently sidestepping the limitations associated with a cavity structure. We present theoretical predictions and experimental results, including improved gain and noise performance. We discuss transmon qubit readout in the circuit QED architecture using a TWPA. We also comment on promising architectures for chip-level integration and multiplexing. Work supported by IARPA.

  4. Erbium Doped Fiber Sources and Amplifiers for Optical Fiber Sensors.

    NASA Astrophysics Data System (ADS)

    Wagener, Jefferson L.

    1996-08-01

    sections on the distribution lines, amplifier spacing that maximizes the output signal to noise ratio is found by equating the noise created by the amplifiers with shot noise. The output signal to noise ratio is shown to be weakly sensitive to the amplifier gain on the distribution lines.

  5. Cascading electron and hole transfer dynamics in a CdS/CdTe core-shell sensitized with bromo-pyrogallol red (Br-PGR): slow charge recombination in type II regime.

    PubMed

    Maity, Partha; Debnath, Tushar; Chopra, Uday; Ghosh, Hirendra Nath

    2015-02-14

    Ultrafast cascading hole and electron transfer dynamics have been demonstrated in a CdS/CdTe type II core-shell sensitized with Br-PGR using transient absorption spectroscopy and the charge recombination dynamics have been compared with those of CdS/Br-PGR composite materials. Steady state optical absorption studies suggest that Br-PGR forms strong charge transfer (CT) complexes with both the CdS QD and CdS/CdTe core-shell. Hole transfer from the photo-excited QD and QD core-shell to Br-PGR was confirmed by both steady state and time-resolved emission spectroscopy. Charge separation was also confirmed by detecting electrons in the conduction band of the QD and the cation radical of Br-PGR as measured from femtosecond transient absorption spectroscopy. Charge separation in the CdS/Br-PGR composite materials was found to take place in three different pathways, by transferring the photo-excited hole of CdS to Br-PGR, electron injection from the photo-excited Br-PGR to the CdS QD, and direct electron transfer from the HOMO of Br-PGR to the conduction band of the CdS QD. However, in the CdS/CdTe/Br-PGR system hole transfer from the photo-excited CdS to Br-PGR and electron injection from the photo-excited Br-PGR to CdS take place after cascading through the CdTe shell QD. Charge separation also takes place via direct electron transfer from the Br-PGR HOMO to the conduction band of CdS/CdTe. Charge recombination (CR) dynamics between the electron in the conduction band of the CdS QD and the Br-PGR cation radical were determined by monitoring the bleach recovery kinetics. The CR dynamics were found to be much slower in the CdS/CdTe/Br-PGR system than in the CdS/Br-PGR system. The formation of the strong CT complex and the separation of charges cascading through the CdTe shell help to slow down charge recombination in the type II regime. PMID:25583154

  6. Low voltage charge-balanced capacitance-voltage conversion circuit for one-side-electrode-type fluid-based inclination sensor

    NASA Astrophysics Data System (ADS)

    Manaf, Asrulnizam Bin Abd; Matsumoto, Yoshinori

    2009-01-01

    A low voltage detection circuit for a capacitance sensor is important for connection to a low voltage digital circuit interface. We studied two different charge-balanced capacitance-voltage ( C- V) conversion circuits configurations; the operational amplifier and the inverter amplifier. Both capacitance detection circuits were designed using 0.35 μm CMOS circuitry technology. Both amplifiers used in the detection circuits were not affected by offset voltage. The current consumption for capacitance detection circuit was reduced from 250 μA at V dd 3.3 V to 38 μA at V dd 1.3 V by switching from an operational amplifier to an inverter amplifier. These circuits were packaged with one-side-electrode-type fluid-based inclination sensors on ceramic substrates. The size of the sensor is ∅ 4.0 mm × 1.0 mm and pure propylene carbonate was used as electrolyte. Changes in temperature did not affect the output voltage of the sensor between -10 °C and 50 °C. This results show that the inverter amplifier used in the detection circuit was not affected by offset voltage and the output voltage V m is depends only on capacitor ratio. The capacitance detection circuit using the inverter amplifier shows a high-sensitivity of about 7 mV/deg over the operational amplifier at V dd 1.3 V. The response time, resolution and minimum moving angle of sensor were 0.7 s, 0.86° and 0.4°, respectively, at V dd 1.3 V for the inverter amplifier type of capacitance detection circuit.

  7. Control of oscillator and amplifier flows

    NASA Astrophysics Data System (ADS)

    Schmid, Peter

    2012-11-01

    Flow control aims at the targeted manipulation of inherent flow behavior and is a critical component in efforts to delay instabilities, reduce drag, decrease receptivities or extend the operational parameter range of a fluid device. The design of flow control strategies relies on a model for the fluid system but also a model for the noise environment. For flows that are insensitive to external noise (oscillator flows), effective control strategies have been designed with considerable success; for flows that respond sensitively to environmental noise (amplifier flows), however, the design of effective control schemes is far more challenging, as it crucially depends on the quality of the noise model. We will present and discuss the critical steps in the design of flow control schemes for both types of flow behavior and compare and contrast a model based and data-based approach. This presentation summarizes joint work with Denis Sipp (ONERA-DAFE) and various doctoral students.

  8. CARM-klystron amplifier for accelerator applications

    NASA Astrophysics Data System (ADS)

    Gold, Steven H.; Fliflet, Arne W.

    2001-05-01

    We consider the possibility of a cyclotron-autoresonance-maser (CARM) klystron configuration for accelerator applications as an alternative to the gyroklystron amplifier. The potential advantages, compared to gyroklystrons, include: 1) comparable efficiencies at lower values of the electron beam pitch ratio α, which should improve the beam quality and make the device substantially more stable against the excitation of parasitic mode, 2) operation far from cutoff, which should reduce the fields at cavity walls, allowing higher power operation, and 3) operation at lower magnetic fields for the same cyclotron harmonic number. However, there are two significant issues associated with the design of efficient, high-power CARMs. First, because of the higher value of kZ, compared to gyroklystrons, CARMs are substantially more sensitive to parallel velocity spread (pitch-angle spread). Second, conventional cavities support a variety of near-cutoff modes, which can compete with the CARM interaction. Therefore, one must consider either Bragg resonators or quasioptical cavity configurations.

  9. Isothermal amplified detection of DNA and RNA.

    PubMed

    Yan, Lei; Zhou, Jie; Zheng, Yue; Gamson, Adam S; Roembke, Benjamin T; Nakayama, Shizuka; Sintim, Herman O

    2014-05-01

    This review highlights various methods that can be used for a sensitive detection of nucleic acids without using thermal cycling procedures, as is done in PCR or LCR. Topics included are nucleic acid sequence-based amplification (NASBA), strand displacement amplification (SDA), loop-mediated amplification (LAMP), Invader assay, rolling circle amplification (RCA), signal mediated amplification of RNA technology (SMART), helicase-dependent amplification (HDA), recombinase polymerase amplification (RPA), nicking endonuclease signal amplification (NESA) and nicking endonuclease assisted nanoparticle activation (NENNA), exonuclease-aided target recycling, Junction or Y-probes, split DNAZyme and deoxyribozyme amplification strategies, template-directed chemical reactions that lead to amplified signals, non-covalent DNA catalytic reactions, hybridization chain reactions (HCR) and detection via the self-assembly of DNA probes to give supramolecular structures. The majority of these isothermal amplification methods can detect DNA or RNA in complex biological matrices and have great potential for use at point-of-care. PMID:24643211

  10. Influence of counter-anions during electrochemical deposition of ZnO on the charge transport dynamics in dye-sensitized solar cells.

    PubMed

    Richter, Christoph; Beu, Max; Schlettwein, Derck

    2015-01-21

    Porous ZnO/EosinY films have been electrochemically deposited by oxygen reduction in the presence of a zinc salt from EosinY-containing aqueous solutions, with either chloride or perchlorate as the counter anion. EosinY was removed and the films were sensitised by D149. These electrodes were used for dye-sensitised solar cells (DSCs), and charge transport in the porous network was studied by intensity modulated current/voltage spectroscopy (IMVS/IMPS) and electrochemical impedance spectroscopy (EIS) under illumination. Doping of ZnO during the electrodeposition could be proven by changes in the charge transport in ZnO and could be shown to occur when chloride was used as the counter ion. By using perchlorate as the counter ion, on the other hand, a more reproducible occupation of trap levels was obtained at, however, slightly lower voltages in DSCs whose origin is discussed in detail. PMID:25474267

  11. Low Cost RF Amplifier for Community TV

    NASA Astrophysics Data System (ADS)

    Ch, Syafaruddin; Sasongko, Sudi Mariyanto Al; Made Budi Suksmadana, I.; Mustiko Okta Muvianto, Cahyo; Ariessaputra, Suthami

    2016-01-01

    he capability of television to deliver audio video makes this media become the most effective method to spread information. This paper presents an experiment of RF amplifier design having low-cost design and providing sufficient RF power particularly for community television. The RF amplifier consists of two stages of amplifier. The first stage amplifier was used to leverage output of TV modulator from 11dBm to enable to drive next stage amplifier. CAD simulation and fabrication were run to reach optimum RF amplifier design circuit. The associated circuit was made by determining stability circle, stability gain, and matching impedance. Hence, the average power of first stage RF amplifier was 24.68dBm achieved. The second stage used RF modules which was ready match to 50 ohm for both input and output port. The experiment results show that the RF amplifier may operate at frequency ranging from 174 to 230MHz. The average output power of the 2nd stage amplifier was 33.38 Watt with the overall gain of 20.54dB. The proposed RF amplifier is a cheap way to have a stable RF amplifier for community TV. The total budget for the designed RF amplifier is only a 1/5 compared to local design of final TV amplifier.

  12. Photoinduced Charge-Transfer State of 4-Carbazolyl-3-(trifluoromethyl)benzoic Acid: Photophysical Property and Application to Reduction of Carbon-Halogen Bonds as a Sensitizer.

    PubMed

    Matsubara, Ryosuke; Shimada, Toshiyuki; Kobori, Yasuhiro; Yabuta, Tatsushi; Osakai, Toshiyuki; Hayashi, Masahiko

    2016-07-20

    The photoinduced persistent intramolecular charge-transfer state of 4-carbazolyl-3-(trifluoromethyl)benzoic acid was confirmed. It showed a higher catalytic activity in terms of yield and selectivity in the photochemical reduction of alkyl halides compared to the parent carbazole. Even unactivated primary alkyl bromides could be reduced by this photocatalyst. The high catalytic activity is rationalized by considering the slower backward single-electron transfer owing to the spatial separation of the donor and acceptor subunits. PMID:27305449

  13. Gold Nanoparticle Labels Amplify Ellipsometric Signals

    NASA Technical Reports Server (NTRS)

    Venkatasubbarao, Srivatsa

    2008-01-01

    The ellipsometric method reported in the immediately preceding article was developed in conjunction with a method of using gold nanoparticles as labels on biomolecules that one seeks to detect. The purpose of the labeling is to exploit the optical properties of the gold nanoparticles in order to amplify the measurable ellipsometric effects and thereby to enable ultrasensitive detection of the labeled biomolecules without need to develop more-complex ellipsometric instrumentation. The colorimetric, polarization, light-scattering, and other optical properties of nanoparticles depend on their sizes and shapes. In the present method, these size-and-shape-dependent properties are used to magnify the polarization of scattered light and the diattenuation and retardance of signals derived from ellipsometry. The size-and-shape-dependent optical properties of the nanoparticles make it possible to interrogate the nanoparticles by use of light of various wavelengths, as appropriate, to optimally detect particles of a specific type at high sensitivity. Hence, by incorporating gold nanoparticles bound to biomolecules as primary or secondary labels, the performance of ellipsometry as a means of detecting the biomolecules can be improved. The use of gold nanoparticles as labels in ellipsometry has been found to afford sensitivity that equals or exceeds the sensitivity achieved by use of fluorescence-based methods. Potential applications for ellipsometric detection of gold nanoparticle-labeled biomolecules include monitoring molecules of interest in biological samples, in-vitro diagnostics, process monitoring, general environmental monitoring, and detection of biohazards.

  14. Does surface roughness amplify wetting?

    SciTech Connect

    Malijevský, Alexandr

    2014-11-14

    Any solid surface is intrinsically rough on the microscopic scale. In this paper, we study the effect of this roughness on the wetting properties of hydrophilic substrates. Macroscopic arguments, such as those leading to the well-known Wenzel's law, predict that surface roughness should amplify the wetting properties of such adsorbents. We use a fundamental measure density functional theory to demonstrate the opposite effect from roughness for microscopically corrugated surfaces, i.e., wetting is hindered. Based on three independent analyses we show that microscopic surface corrugation increases the wetting temperature or even makes the surface hydrophobic. Since for macroscopically corrugated surfaces the solid texture does indeed amplify wetting there must exist a crossover between two length-scale regimes that are distinguished by opposite response on surface roughening. This demonstrates how deceptive can be efforts to extend the thermodynamical laws beyond their macroscopic territory.

  15. Quantum Theory of Laser Amplifiers.

    NASA Astrophysics Data System (ADS)

    Mander, Gillian Linda

    Available from UMI in association with The British Library. Requires signed TDF. We calculate the input-output characteristics of a below threshold laser amplifier. Expressions are derived for the output second- and fourth-order spectral and temporal correlation functions in terms of the corresponding input quantities, and for the photocount first and second factorial moments for both homodyne and direct detection. The general results are applied to several cases of practical interest, including specific non-classical input states. We show that a maximum of twofold amplification is permitted if squeezing in the input is to survive at the output. Similarly, for preservation of photon antibunching in amplification we show that only very small gains are allowed. The model treated here provides a detailed example of the amplifier noise limitations imposed by quantum mechanics. In particular, we show that minimum noise occurs in a cavity that is asymmetric with respect to the mirror reflectivities. The latter part of this work treats the above threshold laser amplifier. The laser output is back-scattered from a moving target to provide a weak Doppler-shifted signal which re-enters the laser cavity and is amplified. We show that the three-level atomic lasing medium is equivalent to a two-level medium pumped by an inverted bath. We use the methods of quantum statistical analysis to obtain time -evolution equations for the c-number amplitudes of the laser and signal fields. We show that the results may be applied to the below threshold regime for appropriate values of the pump parameter. By considering the amplitude differential gain we show explicitly that the behaviour of the laser around threshold is characteristic of a second -order phase transition. We calculate the output intensity gain appropriate to a heterodyne detection process, and find good agreement between the predicted gain profiles and measured data for both carbon dioxide and argon-ion lasers.

  16. High temperature current mirror amplifier

    DOEpatents

    Patterson, III, Raymond B.

    1984-05-22

    A high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg.

  17. 338-GHz Semiconductor Amplifier Module

    NASA Technical Reports Server (NTRS)

    Samoska, Lorene A.; Gaier, Todd C.; Soria, Mary M.; Fung, King Man; Rasisic, Vesna; Deal, William; Leong, Kevin; Mei, Xiao Bing; Yoshida, Wayne; Liu, Po-Hsin; Uyeda, Jansen; Lai, Richard

    2010-01-01

    Research findings were reported from an investigation of new gallium nitride (GaN) monolithic millimeter-wave integrated circuit (MMIC) power amplifiers (PAs) targeting the highest output power and the highest efficiency for class-A operation in W-band (75-110 GHz). W-band PAs are a major component of many frequency multiplied submillimeter-wave LO signal sources. For spectrometer arrays, substantial W-band power is required due to the passive lossy frequency multipliers.

  18. High power gas laser amplifier

    DOEpatents

    Leland, Wallace T.; Stratton, Thomas F.

    1981-01-01

    A high power output CO.sub.2 gas laser amplifier having a number of sections, each comprising a plurality of annular pumping chambers spaced around the circumference of a vacuum chamber containing a cold cathode, gridded electron gun. The electron beam from the electron gun ionizes the gas lasing medium in the sections. An input laser beam is split into a plurality of annular beams, each passing through the sections comprising one pumping chamber.

  19. Small and lightweight power amplifiers

    NASA Astrophysics Data System (ADS)

    Shams, Qamar A.; Barnes, Kevin N.; Fox, Robert L.; Moses, Robert W.; Bryant, Robert G.; Robinson, Paul C.; Shirvani, Mir

    2002-07-01

    The control of u wanted structural vibration is implicit in most of NASA's programs. Currently several approaches to control vibrations in large, lightweight, deployable structures and twin tail aircraft at high angles of attack are being evaluated. The Air Force has been examining a vertical tail buffet load alleviation system that can be integrated onboard an F/A-18 and flown. Previous wind tunnel and full-scale ground tests using distributed actuators have shown that the concept works; however, there is insufficient rom available onboard an F/A-18 to store current state-of- the-art system components such as amplifiers, DC-to-DC converter and a computer for performing vibration suppression. Sensor processing, power electronics, DC-to-DC converters, and control electronics that may be collocated with distributed actuators, are particularly desirable. Such electronic system would obviate the need for complex, centralized, control processing and power distribution components that will eliminate the weight associated with lengthy wiring and cabling networks. Several small and lightweight power amplifiers ranging from 300V pp to 650V pp have been designed using off the shelf components for different applications. In this paper, the design and testing of these amplifiers will be presented under various electrical loads.

  20. Compact, harmonic multiplying gyrotron amplifiers

    SciTech Connect

    Guo, H.Z.; Granatstein, V.L.; Antonsen, T.M. Jr.; Levush, B.; Tate, J.; Chen, S.H.

    1995-12-31

    A compact, harmonic multiplying gyrotron traveling wave amplifier is being developed. The device is a three-stage tube with the output section running as a fourth harmonic gyro-TWT, the input section running as a fundamental gyro-TWT, and the middle operating at the second harmonic of the cyclotron frequency. Radiation is suppressed by servers between the sections. The operating beam of the tube is produced by a magnetron injection gun (MIG). A TE{sub 0n} mode selective interaction circuit consisting of mode converters and a filter waveguide is employed for both input and output sections to solve the mode competition problem, which is pervasive in gyro-TWT operation. The input section has an input coupler designed as a TE{sub 0n} mode launcher. It excites a signal at the fundamental cyclotron frequency (17.5 GHz), which is amplified in the first TWT interaction region. So far the device is similar to a two-stage harmonic gyro-TWT. The distinction is that in the three-stage device the second section will be optimized not for output power but for fourth harmonic bunching of the beam. A gyroklystron amplifier has also been designed. The configuration is similar to the gyro-TWT but with the traveling wave interaction structures replaced by mode selective special complex cavities. Cold test results of the wideband input coupler and the TE{sub 0n} mode selective interaction circuit have been obtained.

  1. High power regenerative laser amplifier

    DOEpatents

    Miller, J.L.; Hackel, L.A.; Dane, C.B.; Zapata, L.E.

    1994-02-08

    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse. 7 figures.

  2. High power regenerative laser amplifier

    DOEpatents

    Miller, John L.; Hackel, Lloyd A.; Dane, Clifford B.; Zapata, Luis E.

    1994-01-01

    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse.

  3. Cascading electron and hole transfer dynamics in a CdS/CdTe core-shell sensitized with bromo-pyrogallol red (Br-PGR): slow charge recombination in type II regime

    NASA Astrophysics Data System (ADS)

    Maity, Partha; Debnath, Tushar; Chopra, Uday; Ghosh, Hirendra Nath

    2015-01-01

    Ultrafast cascading hole and electron transfer dynamics have been demonstrated in a CdS/CdTe type II core-shell sensitized with Br-PGR using transient absorption spectroscopy and the charge recombination dynamics have been compared with those of CdS/Br-PGR composite materials. Steady state optical absorption studies suggest that Br-PGR forms strong charge transfer (CT) complexes with both the CdS QD and CdS/CdTe core-shell. Hole transfer from the photo-excited QD and QD core-shell to Br-PGR was confirmed by both steady state and time-resolved emission spectroscopy. Charge separation was also confirmed by detecting electrons in the conduction band of the QD and the cation radical of Br-PGR as measured from femtosecond transient absorption spectroscopy. Charge separation in the CdS/Br-PGR composite materials was found to take place in three different pathways, by transferring the photo-excited hole of CdS to Br-PGR, electron injection from the photo-excited Br-PGR to the CdS QD, and direct electron transfer from the HOMO of Br-PGR to the conduction band of the CdS QD. However, in the CdS/CdTe/Br-PGR system hole transfer from the photo-excited CdS to Br-PGR and electron injection from the photo-excited Br-PGR to CdS take place after cascading through the CdTe shell QD. Charge separation also takes place via direct electron transfer from the Br-PGR HOMO to the conduction band of CdS/CdTe. Charge recombination (CR) dynamics between the electron in the conduction band of the CdS QD and the Br-PGR cation radical were determined by monitoring the bleach recovery kinetics. The CR dynamics were found to be much slower in the CdS/CdTe/Br-PGR system than in the CdS/Br-PGR system. The formation of the strong CT complex and the separation of charges cascading through the CdTe shell help to slow down charge recombination in the type II regime.Ultrafast cascading hole and electron transfer dynamics have been demonstrated in a CdS/CdTe type II core-shell sensitized with Br

  4. Ultra low-noise charge coupled device

    NASA Technical Reports Server (NTRS)

    Janesick, James R. (Inventor)

    1993-01-01

    Special purpose CCD designed for ultra low-noise imaging and spectroscopy applications that require subelectron read noise floors, wherein a non-destructive output circuit operating near its 1/f noise regime is clocked in a special manner to read a single pixel multiple times. Off-chip electronics average the multiple values, reducing the random noise by the square-root of the number of samples taken. Noise floors below 0.5 electrons rms are possible in this manner. In a preferred embodiment of the invention, a three-phase CCD horizontal register is used to bring a pixel charge packet to an input gate adjacent a floating gate amplifier. The charge is then repeatedly clocked back and forth between the input gate and the floating gate. Each time the charge is injected into the potential well of the floating gate, it is sensed non-destructively. The floating gate amplifier is provided with a reference voltage of a fixed value and a pre-charge gate for resetting the amplifier between charge samples to a constant gain. After the charge is repeatedly sampled a selected number of times, it is transferred by means of output gates, back into the horizontal register, where it is clocked in a conventional manner to a diffusion MOSFET amplifier. It can then be either sampled (destructively) one more time or otherwise discarded.

  5. Cooled Low-Noise HEMT Microwave Amplifiers

    NASA Technical Reports Server (NTRS)

    Bautista, J. Javier; Ortiz, Gerardo G.; Duh, Kuanghann George

    1992-01-01

    Prototype cooled low-noise microwave amplifiers based on high-electron-mobility transistors (HEMT's) considered as replacements for cooled ruby masers used as low-noise receiver-front-end amplifiers in communications, radio science, radar systems, radio astronomy, and telemetry. HEMT amplifier operates at 12 K, requires less cooling power and operates at lower cost with simpler, more-reliable cooling system.

  6. Bio-isolated DC operational amplifier

    NASA Technical Reports Server (NTRS)

    Lee, R. D.

    1974-01-01

    Possibility of shocks from leakage currents can be reduced by use of isolated preamplifiers. Amplifier consists of battery-powered operational amplifier coupled by means of light-emitting diodes to another amplifier which may be grounded and operated from ac power mains or separate battery supply.

  7. NASA developments in solid state power amplifiers

    NASA Technical Reports Server (NTRS)

    Leonard, Regis F.

    1990-01-01

    Over the last ten years, NASA has undertaken an extensive program aimed at development of solid state power amplifiers for space applications. Historically, the program may be divided into three phases. The first efforts were carried out in support of the advanced communications technology satellite (ACTS) program, which is developing an experimental version of a Ka-band commercial communications system. These first amplifiers attempted to use hybrid technology. The second phase was still targeted at ACTS frequencies, but concentrated on monolithic implementations, while the current, third phase, is a monolithic effort that focusses on frequencies appropriate for other NASA programs and stresses amplifier efficiency. The topics covered include: (1) 20 GHz hybrid amplifiers; (2) 20 GHz monolithic MESFET power amplifiers; (3) Texas Instruments' (TI) 20 GHz variable power amplifier; (4) TI 20 GHz high power amplifier; (5) high efficiency monolithic power amplifiers; (6) GHz high efficiency variable power amplifier; (7) TI 32 GHz monolithic power amplifier performance; (8) design goals for Hughes' 32 GHz variable power amplifier; and (9) performance goals for Hughes' pseudomorphic 60 GHz power amplifier.

  8. Design of hysteresis circuits using differential amplifiers

    NASA Technical Reports Server (NTRS)

    Cooke, W. A.

    1971-01-01

    Design equations for hysteresis circuit are based on the following assumptions: amplifier input impedance is larger than source impedance; amplifier output impedance is less than load impedance; and amplifier switches state when differential input voltage is approximately zero. Circuits are designed to any given specifications.

  9. Solid state ku-band power amplifier

    NASA Technical Reports Server (NTRS)

    Bowers, H. C.; Lockyear, W. H.

    1972-01-01

    The design, fabrication, and testing of two types of IMPATT diode reflection amplifiers and a transmission amplifier are given. The Ku-band IMPATT diode development is discussed. Circuitry and electrical performance of the final version of the Ku-band amplifier is described. Construction details and an outline and mounting drawing are presented.

  10. Solid state, S-band, power amplifier

    NASA Technical Reports Server (NTRS)

    Digrindakis, M.

    1973-01-01

    The final design and specifications for a solid state, S-band, power amplifier is reported. Modifications from a previously proposed design were incorporated to improve efficiency and meet input overdrive and noise floor requirements. Reports on the system design, driver amplifier, power amplifier, and voltage and current limiter are included along with a discussion of the testing program.

  11. Charge Transfer Dynamics at Dye-Sensitized ZnO and TiO2 Interfaces Studied by Ultrafast XUV Photoelectron Spectroscopy

    NASA Astrophysics Data System (ADS)

    Borgwardt, Mario; Wilke, Martin; Kampen, Thorsten; Mähl, Sven; Xiao, Manda; Spiccia, Leone; Lange, Kathrin M.; Kiyan, Igor Yu.; Aziz, Emad F.

    2016-04-01

    Interfacial charge transfer from photoexcited ruthenium-based N3 dye molecules into ZnO thin films received controversial interpretations. To identify the physical origin for the delayed electron transfer in ZnO compared to TiO2, we probe directly the electronic structure at both dye-semiconductor interfaces by applying ultrafast XUV photoemission spectroscopy. In the range of pump-probe time delays between 0.5 to 1.0 ps, the transient signal of the intermediate states was compared, revealing a distinct difference in their electron binding energies of 0.4 eV. This finding strongly indicates the nature of the charge injection at the ZnO interface associated with the formation of an interfacial electron-cation complex. It further highlights that the energetic alignment between the dye donor and semiconductor acceptor states appears to be of minor importance for the injection kinetics and that the injection efficiency is dominated by the electronic coupling.

  12. Charge Transfer Dynamics at Dye-Sensitized ZnO and TiO2 Interfaces Studied by Ultrafast XUV Photoelectron Spectroscopy

    PubMed Central

    Borgwardt, Mario; Wilke, Martin; Kampen, Thorsten; Mähl, Sven; Xiao, Manda; Spiccia, Leone; Lange, Kathrin M.; Kiyan, Igor Yu.; Aziz, Emad F.

    2016-01-01

    Interfacial charge transfer from photoexcited ruthenium-based N3 dye molecules into ZnO thin films received controversial interpretations. To identify the physical origin for the delayed electron transfer in ZnO compared to TiO2, we probe directly the electronic structure at both dye-semiconductor interfaces by applying ultrafast XUV photoemission spectroscopy. In the range of pump-probe time delays between 0.5 to 1.0 ps, the transient signal of the intermediate states was compared, revealing a distinct difference in their electron binding energies of 0.4 eV. This finding strongly indicates the nature of the charge injection at the ZnO interface associated with the formation of an interfacial electron-cation complex. It further highlights that the energetic alignment between the dye donor and semiconductor acceptor states appears to be of minor importance for the injection kinetics and that the injection efficiency is dominated by the electronic coupling. PMID:27073060

  13. Charge Transfer Dynamics at Dye-Sensitized ZnO and TiO2 Interfaces Studied by Ultrafast XUV Photoelectron Spectroscopy.

    PubMed

    Borgwardt, Mario; Wilke, Martin; Kampen, Thorsten; Mähl, Sven; Xiao, Manda; Spiccia, Leone; Lange, Kathrin M; Kiyan, Igor Yu; Aziz, Emad F

    2016-01-01

    Interfacial charge transfer from photoexcited ruthenium-based N3 dye molecules into ZnO thin films received controversial interpretations. To identify the physical origin for the delayed electron transfer in ZnO compared to TiO2, we probe directly the electronic structure at both dye-semiconductor interfaces by applying ultrafast XUV photoemission spectroscopy. In the range of pump-probe time delays between 0.5 to 1.0 ps, the transient signal of the intermediate states was compared, revealing a distinct difference in their electron binding energies of 0.4 eV. This finding strongly indicates the nature of the charge injection at the ZnO interface associated with the formation of an interfacial electron-cation complex. It further highlights that the energetic alignment between the dye donor and semiconductor acceptor states appears to be of minor importance for the injection kinetics and that the injection efficiency is dominated by the electronic coupling. PMID:27073060

  14. Log amplifier with pole-zero compensation

    DOEpatents

    Brookshier, William

    1987-01-01

    A logarithmic amplifier circuit provides pole-zero compensation for improved stability and response time over 6-8 decades of input signal frequency. The amplifier circuit includes a first operational amplifier with a first feedback loop which includes a second, inverting operational amplifier in a second feedback loop. The compensated output signal is provided by the second operational amplifier with the log elements, i.e., resistors, and the compensating capacitors in each of the feedback loops having equal values so that each break point or pole is offset by a compensating break point or zero.

  15. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.

    SciTech Connect

    BEN-ZVI, ILAN, DAYRAN, D.; LITVINENKO, V.

    2005-08-21

    Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department.

  16. ULTRA-STABILIZED D. C. AMPLIFIER

    DOEpatents

    Hartwig, E.C.; Kuenning, R.W.; Acker, R.C.

    1959-02-17

    An improved circuit is described for stabilizing the drift and minimizing the noise and hum level of d-c amplifiers so that the output voltage will be zero when the input is zero. In its detailed aspects, the disclosed circuit incorporates a d-c amplifier having a signal input, a second input, and an output circuit coupled back to the first input of the amplifier through inverse feedback means. An electronically driven chopper having a pair of fixed contacts and a moveable contact alternately connects the two inputs of a difference amplifier to the signal input. The A. E. error signal produced in the difference amplifier is amplified, rectified, and applied to the second input of the amplifier as the d-c stabilizing voltage.

  17. Direct solar-pumped iodine laser amplifier

    NASA Technical Reports Server (NTRS)

    Han, K. S.

    1985-01-01

    This semiannual progress report covers the period from April 1, 1985 to Sept. 30, 1985 under NASA grant NAS1-441 entitled direct solar pumped iodine laser amplifier. During this period the parametric studies of the iodine laser oscillator pumped by a Vortek simulator was carried out before the amplifier studies. The amplifier studies are postponed to the extended period following completion of the parametric studies. In addition, the kinetic modeling of a solar pumped iodine laser amplifier, and the experimental work for a solar pumped dye laser amplifier are in progress. This report contains three parts: (1) the radiation characteristics of solar simulator and the parametric characteristics of photodissociation iodine laser continuously pumped by a Vortek solar simulator; (2) kinetic modeling of a solar pumped iodine laser amplifier; and (3) the study of the dye laser amplifier pumped by a Tamarack solar simulator.

  18. Nondegenerate optical parametric chirped pulse amplifier

    DOEpatents

    Jovanovic, Igor; Ebbers, Christopher A.

    2005-03-22

    A system provides an input pump pulse and a signal pulse. A first dichroic beamsplitter is highly reflective for the input signal pulse and highly transmissive for the input pump pulse. A first optical parametric amplifier nonlinear crystal transfers part of the energy from the input pump pulse to the input signal pulse resulting in a first amplified signal pulse and a first depleted pump pulse. A second dichroic beamsplitter is highly reflective for the first amplified signal pulse and highly transmissive for the first depleted pump pulse. A second optical parametric amplifier nonlinear crystal transfers part of the energy from the first depleted pump pulse to the first amplified signal pulse resulting in a second amplified signal pulse and a second depleted pump pulse. A third dichroic beamsplitter receives the second amplified signal pulse and the second depleted pump pulse. The second depleted pump pulse is discarded.

  19. Investigation of noise and contrast sensitivity of an electron multiplying charge-coupled device (EMCCD) based cone beam micro-CT system

    NASA Astrophysics Data System (ADS)

    Bysani Krishnakumar, Sumukh; Podgorsak, Alexander R.; Setlur Nagesh, S. V.; Jain, Amit; Rudin, Stephen; Bednarek, Daniel R.; Ionita, Ciprian N.

    2016-03-01

    A small animal micro-CT system was built using an EMCCD detectors having complex pre-digitization amplification technology, high-resolution, high-sensitivity and low-noise. Noise in CBCT reconstructed images when using predigitization amplification behaves differently than commonly used detectors and warrants a detailed investigation. In this study, noise power and contrast sensitivity were estimated for the newly built system. Noise analysis was performed by scanning a water phantom. Tube voltage was lowered to minimum delivered by the tube (20 kVp and 0.5 mA) and detector gain was varied. Contrast sensitivity was analyzed by using a phantom containing different iodine contrast solutions (20% to 70%) filled in six different tubes. First, we scanned the phantom using various x-ray exposures at 40 kVp while changing the gain to maintain the background air value of the projection images constant. Next, the exposure was varied while the detector gain was maintained constant. Radial NPS plots show that noise power level increases as gain increases. Contrast sensitivity was analyzed by calculating ratio of signal-to-noise ratios (SNR) for increased gain with those of low constant gain at each exposure. The SNR value at low constant gain was always lower than SNR of high detector gain at all x-ray settings and iodine contrast. The largest increase of SNR approached 1.3 for low contrast feature for an iodine concentration of 20%. Despite an increase in noise level as gain increases, the SNR improvement shows that signal level also increases because of the unique on-chip gain of the detector.

  20. Introduction of Peripheral Carboxylates to Decrease the Charge on Tm(3+) DOTAM-Alkyl Complexes: Implications for Detection Sensitivity and in Vivo Toxicity of PARACEST MRI Contrast Agents.

    PubMed

    Suchý, Mojmír; Milne, Mark; Elmehriki, Adam A H; McVicar, Nevin; Li, Alex X; Bartha, Robert; Hudson, Robert H E

    2015-08-27

    A series of structurally modified Tm(3+) DOTAM-alkyl complexes as potential PARACEST MRI contrast agents has been synthesized with the aim to decrease the overall positive charge associated with these molecules and increase their biocompatibility. Two types of structural modification have been performed, an introduction of terminal carboxylate arms to the alkyl side chains and a conjugation of one of the alkyl side chains with aspartic acid. Detailed evaluation of the magnetic resonance imaging chemical exchange contrast associated with the structurally modified contrast agents has been performed. In contrast to the acutely toxic Tm(3+) DOTAM-alkyl complexes, the structurally modified compounds were found to be tolerated well during in vivo MRI studies in mice; however, only the aspartic acid modified chelates produced an amide proton-based PARACEST signal. PMID:26214576

  1. Efficient Blue-Colored Solid-State Dye-Sensitized Solar Cells: Enhanced Charge Collection by Using an in Situ Photoelectrochemically Generated Conducting Polymer Hole Conductor.

    PubMed

    Zhang, Jinbao; Vlachopoulos, Nick; Hao, Yan; Holcombe, Thomas W; Boschloo, Gerrit; Johansson, Erik M J; Grätzel, Michael; Hagfeldt, Anders

    2016-05-18

    A high power conversion efficiency (PCE) of 5.5 % was achieved by efficiently incorporating a diketopyrrolopyrrole-based dye with a conducting polymer poly(3,4-ethylenediothiophene) (PEDOT) hole-transporting material (HTM) that was formed in situ, compared with a PCE of 2.9 % for small molecular spiro-OMeTAD-based solid-state dye solar cells (sDSCs). The high PCE for PEDOT-based sDSCs is mainly attributed to the significantly enhanced charge-collection efficiency, as a result of the three-order-of-magnitude higher hole conductivity (0.53 S cm(-1) ) compared with that of the widely used low molecular weight HTM spiro-OMeTAD (3.5×10(-4)  S cm(-1) ). PMID:26919196

  2. Bactericidal Dendritic Polycation Cloaked with Stealth Material via Lipase-Sensitive Intersegment Acquires Neutral Surface Charge without Losing Membrane-Disruptive Activity.

    PubMed

    Xu, Lulu; He, Chen; Hui, Liwei; Xie, Yuntao; Li, Jia-Min; He, Wei-Dong; Yang, Lihua

    2015-12-23

    Net cationicity of membrane-disruptive antimicrobials is necessary for their activity but may elicit immune attack when administered intravenously. By cloaking a dendritic polycation (G2) with poly(caprolactone-b-ethylene glycol) (PCL-b-PEG), we obtain a nanoparticle antimicrobial, G2-g-(PCL-b-PEG), which exhibits neutral surface charge but kills >99.9% of inoculated bacterial cells at ≤8 μg/mL. The observed activity may be attributed PCL's responsive degradation by bacterial lipase and the consequent exposure of the membrane-disruptive, bactericidal G2 core. Moreover, G2-g-(PCL-b-PEG) exhibits good colloidal stability in the presence of serum and insignificant hemolytic toxicity even at ≥2048 μg/mL. suggesting good blood compatibility required for intravenous administration. PMID:26632646

  3. Novel photoacid generators for chemically amplified resists

    NASA Astrophysics Data System (ADS)

    Yamato, Hitoshi; Asakura, Toshikage; Matsumoto, Akira; Ohwa, Masaki

    2002-07-01

    Recently we have developed new class of non-ionic oxime sulfonate PAG. The compounds generate various kinds of sulfonic acids, such as n-propane, n-octane, camphor and p-toluene sulfonic acid under Deep-UV exposure and are applicable for chemically amplified (CA) photoresists. The application-relevant properties of the compounds such as solubility in propylene glycol monomethyl ether acetate (PGMEA), ethyl lactate, ethyl 3-ethoxypropionate, and 2-heptanone, UV absorption, thermal stability with or without poly(4-hydroxystyrene) (PHS), storage stability in a neat form or in PGMEA solution with or without additives, sensitivity in a model resist formulation, dissolution inhibition efficiency during the development process and volatility were evaluated. The compounds exhibit good solubility in PGMEA, high sensitivity in positive tone CA resist formulations, with Deep-UV exposure, and no significant volatility. Especially it was found that the compounds are superior in terms of thermal stability and storage stability, i.e., high thermal stability up to 188 degree(s)C in a phenolic matrix, and no change during storage in PGMEA at 60 degree(s)C for 5 months.

  4. Cryogenic CMOS circuits for single charge digital readout.

    SciTech Connect

    Gurrieri, Thomas M.; Longoria, Erin Michelle; Eng, Kevin; Carroll, Malcolm S.; Hamlet, Jason R.; Young, Ralph Watson

    2010-03-01

    The readout of a solid state qubit often relies on single charge sensitive electrometry. However the combination of fast and accurate measurements is non trivial due to large RC time constants due to the electrometers resistance and shunt capacitance from wires between the cold stage and room temperature. Currently fast sensitive measurements are accomplished through rf reflectrometry. I will present an alternative single charge readout technique based on cryogenic CMOS circuits in hopes to improve speed, signal-to-noise, power consumption and simplicity in implementation. The readout circuit is based on a current comparator where changes in current from an electrometer will trigger a digital output. These circuits were fabricated using Sandia's 0.35 {micro}m CMOS foundry process. Initial measurements of comparators with an addition a current amplifier have displayed current sensitivities of < 1nA at 4.2K, switching speeds up to {approx}120ns, while consuming {approx}10 {micro}W. I will also discuss an investigation of noise characterization of our CMOS process in hopes to obtain a better understanding of the ultimate limit in signal to noise performance.

  5. Cryogenic CMOS circuits for single charge digital readout

    NASA Astrophysics Data System (ADS)

    Eng, Kevin; Gurrieri, T. M.; Hamlet, J.; Carroll, M. S.

    2010-03-01

    The readout of a solid state qubit often relies on single charge sensitive electrometry. However the combination of fast and accurate measurements is non trivial due to large RC time constants due to the electrometers resistance and shunt capacitance from wires between the cold stage and room temperature. Currently fast sensitive measurements are accomplished through rf reflectrometry. I will present an alternative single charge readout technique based on cryogenic CMOS circuits in hopes to improve speed, signal-to-noise, power consumption and simplicity in implementation. The readout circuit is based on a current comparator where changes in current from an electrometer will trigger a digital output. These circuits were fabricated using Sandia's 0.35μm CMOS foundry process. Initial measurements of comparators with an addition a current amplifier have displayed current sensitivities of < 1nA at 4.2K, switching speeds up to ˜120ns, while consuming ˜10μW. I will also discuss an investigation of noise characterization of our CMOS process in hopes to obtain a better understanding of the ultimate limit in signal to noise performance.

  6. High temperature current mirror amplifier

    DOEpatents

    Patterson, R.B. III.

    1984-05-22

    Disclosed is a high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg. 2 figs.

  7. High power RF solid state power amplifier system

    NASA Technical Reports Server (NTRS)

    Sims, III, William Herbert (Inventor); Chavers, Donald Gregory (Inventor); Richeson, James J. (Inventor)

    2011-01-01

    A high power, high frequency, solid state power amplifier system includes a plurality of input multiple port splitters for receiving a high-frequency input and for dividing the input into a plurality of outputs and a plurality of solid state amplifier units. Each amplifier unit includes a plurality of amplifiers, and each amplifier is individually connected to one of the outputs of multiport splitters and produces a corresponding amplified output. A plurality of multiport combiners combine the amplified outputs of the amplifiers of each of the amplifier units to a combined output. Automatic level control protection circuitry protects the amplifiers and maintains a substantial constant amplifier power output.

  8. Progress in the development of integrating JFET amplifiers

    NASA Technical Reports Server (NTRS)

    Low, F. J.; Alwardi, M.

    1986-01-01

    A new approach to infrared detector readout has appeared with the development of integrating JFET amplifiers. This brief progress report includes results on the operation of commercially available devices at a temperature of 40 K, on their sensitivity and on an effort to develop a new JFET with properties optimized for cryogenic applications. Even with presently available devices it will be shown that for applications such as the Space Infrared Telescope Facility (SIRTF), the most strigent sensitivity requirements of noise currents as low as 1 electron/sec in less than 100 seconds of integration can be met.

  9. The spectacular human nose: an amplifier of individual quality?

    PubMed Central

    Mikalsen, Åse Kristine Rognmo; Yoccoz, Nigel Gilles; Laeng, Bruno

    2014-01-01

    Amplifiers are signals that improve the perception of underlying differences in quality. They are cost free and advantageous to high quality individuals, but disadvantageous to low quality individuals, as poor quality is easier perceived because of the amplifier. For an amplifier to evolve, the average fitness benefit to the high quality individuals should be higher than the average cost for the low quality individuals. The human nose is, compared to the nose of most other primates, extraordinary large, fragile and easily broken—especially in male–male interactions. May it have evolved as an amplifier among high quality individuals, allowing easy assessment of individual quality and influencing the perception of attractiveness? We tested the latter by manipulating the position of the nose tip or, as a control, the mouth in facial pictures and had the pictures rated for attractiveness. Our results show that facial attractiveness failed to be influenced by mouth manipulations. Yet, facial attractiveness increased when the nose tip was artificially centered according to other facial features. Conversely, attractiveness decreased when the nose tip was displaced away from its central position. Our results suggest that our evaluation of attractiveness is clearly sensitive to the centering of the nose tip, possibly because it affects our perception of the face’s symmetry and/or averageness. However, whether such centering is related to individual quality remains unclear. PMID:24765588

  10. Resonance energy transfer-amplifying fluorescence quenching at the surface of silica nanoparticles toward ultrasensitive detection of TNT.

    PubMed

    Gao, Daming; Wang, Zhenyang; Liu, Bianhua; Ni, Lin; Wu, Minghong; Zhang, Zhongping

    2008-11-15

    This paper reports a resonance energy transfer-amplifying fluorescence quenching at the surface of silica nanoparticles for the ultrasensitive detection of 2,4,6-trinitrotoluene (TNT) in solution and vapor environments. Fluorescence dye and organic amine were covalently modified onto the surface of silica nanoparticles to form a hybrid monolayer of dye fluorophores and amine ligands. The fluorescent silica particles can specifically bind TNT species by the charge-transfer complexing interaction between electron-rich amine ligands and electron-deficient aromatic rings. The resultant TNT-amine complexes bound at the silica surface can strongly suppress the fluorescence emission of the chosen dye by the fluorescence resonance energy transfer (FRET) from dye donor to the irradiative TNT-amine acceptor through intermolecular polar-polar interactions at spatial proximity. The quenching efficiency of the hybrid nanoparticles with TNT is greatly amplified by at least 10-fold that of the corresponding pure dye. The nanoparticle-assembled arrays on silicon wafer can sensitively detect down to approximately 1 nM TNT with the use of only 10 microL of solution (approximately 2 pg TNT) and several ppb of TNT vapor in air. The simple FRET-based nanoparticle sensors reported here exhibit a high and stable fluorescence brightness, strong analyte affinity, and good assembly flexibility and can thus find many applications in the detection of ultratrace analytes. PMID:18847285

  11. Charge sniffer for electrostatics demonstrations

    NASA Astrophysics Data System (ADS)

    Dinca, Mihai P.

    2011-02-01

    An electronic electroscope with a special design for demonstrations and experiments on static electricity is described. It operates as an electric charge sniffer by detecting slightly charged objects when they are brought to the front of its sensing electrode. The sniffer has the advantage of combining high directional sensitivity with a logarithmic bar display. It allows for the identification of electric charge polarity during charge separation by friction, peeling, electrostatic induction, batteries, or secondary coils of power transformers. Other experiments in electrostatics, such as observing the electric field of an oscillating dipole and the distance dependence of the electric field generated by simple charge configurations, are also described.

  12. Effects Of Environmental Electrical Charges On Spacecraft

    NASA Technical Reports Server (NTRS)

    Robinson, Paul A., Jr.

    1993-01-01

    Handbook presents information on three kinds of disruptive effects of environmental electrical charges upon operations of electronic circuits and other sensitive equipment in spacecraft. Addresses surface and internal charging and discharging, single-event upsets, and related design issues.

  13. Multistaged stokes injected Raman capillary waveguide amplifier

    DOEpatents

    Kurnit, Norman A.

    1980-01-01

    A multistaged Stokes injected Raman capillary waveguide amplifier for providing a high gain Stokes output signal. The amplifier uses a plurality of optically coupled capillary waveguide amplifiers and one or more regenerative amplifiers to increase Stokes gain to a level sufficient for power amplification. Power amplification is provided by a multifocused Raman gain cell or a large diameter capillary waveguide. An external source of CO.sub.2 laser radiation can be injected into each of the capillary waveguide amplifier stages to increase Raman gain. Devices for injecting external sources of CO.sub.2 radiation include: dichroic mirrors, prisms, gratings and Ge Brewster plates. Alternatively, the CO.sub.2 input radiation to the first stage can be coupled and amplified between successive stages.

  14. High-efficiency solid state power amplifier

    NASA Technical Reports Server (NTRS)

    Wallis, Robert E. (Inventor); Cheng, Sheng (Inventor)

    2005-01-01

    A high-efficiency solid state power amplifier (SSPA) for specific use in a spacecraft is provided. The SSPA has a mass of less than 850 g and includes two different X-band power amplifier sections, i.e., a lumped power amplifier with a single 11-W output and a distributed power amplifier with eight 2.75-W outputs. These two amplifier sections provide output power that is scalable from 11 to 15 watts without major design changes. Five different hybrid microcircuits, including high-efficiency Heterostructure Field Effect Transistor (HFET) amplifiers and Monolithic Microwave Integrated Circuit (MMIC) phase shifters have been developed for use within the SSPA. A highly efficient packaging approach enables the integration of a large number of hybrid circuits into the SSPA.

  15. Silicon Nanoparticles as Amplifiers of the Ultrasonic Effect in Sonodynamic Therapy.

    PubMed

    Osminkina, L A; Kudryavtsev, A A; Zinovyev, S V; Sviridov, A P; Kargina, Yu V; Tamarov, K P; Nikiforov, V N; Ivanov, A V; Vasilyev, A N; Timoshenko, V Yu

    2016-06-01

    The possibility of using mesoporous silicon nanoparticles as amplifiers (sensitizers) of therapeutic ultrasonic exposure were studied experimentally in vitro and in vivo. The combination of nanoparticles and ultrasound led to a significant inhibition of Hep-2 cancer cell proliferation and Lewis lung carcinoma growth in mice. These results indicated good prospects of using silicon nanoparticles as sensitizers for sonodynamic therapy of tumors. PMID:27388631

  16. Signal-Conditioning Amplifier Recorders

    NASA Technical Reports Server (NTRS)

    Medelius, Pedro J.; Taylor, John

    2003-01-01

    Signal-conditioning amplifier recorders (SCAmpRs) have been proposed as a means of simplifying and upgrading the Kennedy Space Center (KSC) Ground Measurement System (GMS), which is a versatile data-acquisition system that gathers and records a variety of measurement data before and during the launch of a space shuttle. In the present version of the GMS system, signal conditioning amplifiers digitize and transmit data to a VME chassis that multiplexes up to 416 channels. The data is transmitted via a high-speed data bus to a second VME chassis where it is available for snapshots. The data is passed from the second VME chassis to a high-speed data recorder. This process is duplicated for installations at two launch pads and the Vehicle Assembly Building (VAB). Since any failure of equipment in the data path results in loss of data, much of the system is redundant. The architecture of the existing GMS limits expansion or any modification to the system to meet changing requirements because of the cost and time required. A SCAmpR-based system is much more flexible. The basis of the simplification, flexibility, and reliability is the shifting of the recording function to the individual amplifier channels. Each SCAmpR is a self-contained single channel data acquisition system, which in its current implementation, has a data storage capacity of up to 30 minutes when operating at the fastest data sampling rates. The SCAmpR channels are self-configuring and self-calibrating. Multiple SCAmpR channels are ganged on printed circuit boards and mounted in a chassis that provides power, a network hub, and Inter-Range Instrument Group (IRIG) time signals. The SCAmpR channels share nothing except physical mounting on a circuit board. All circuitry is electrically separate for each channel. All that is necessary to complete the data acquisition system is a single master computer tied to the SCAmpR channels by standard network equipment. The size of the data acquisition system

  17. Broadband Microwave Amplifier Design with Lumped Elements

    NASA Astrophysics Data System (ADS)

    Şengül, Metin

    2016-03-01

    This study introduces a broadband microwave amplifier design that utilizes the measured scattering parameters of active devices without assuming an initial topology for the matching networks or an analytic form of the system transfer function. The algorithm can be extended to design multistage broadband microwave amplifiers. An example is given to illustrate the application of the proposed method. It was found that the proposed method provides very good initials for CAD tools to further improve amplifier performance by working on the element values.

  18. Simulation of a regenerative MW FEL amplifier

    SciTech Connect

    Nguyen, R.T.; Colson, W.B.; Wong, R.K.; Sheffield, R.L.

    1997-08-01

    Both oscillator and regenerative amplifier configurations are being studied to optimize the design of a MW class FEL. The regenerative amplifier uses a longer undulator and relies on higher extraction efficiency to achieve high average power, whereas the oscillator is a more compact overall design requiring the transport of the high energy electron beam around bends for energy recovery. Using parameters extrapolated from the 1 kW LANL regenerative amplifier, simulations study the feasibility of achieving 1 MW average power.

  19. A dc amplifier for nuclear particle measurement

    NASA Technical Reports Server (NTRS)

    Macnee, A. B.; Masnari, N. A.

    1978-01-01

    A monolithic preamplifier-postamplifier combination has been developed for use with solid state particle detectors. The direct coupled amplifiers employ interdigitated n-channel JFET's, diodes, and diffused resistors. The circuits developed demonstrate the feasibility of matching the performance of existing discrete component designs. The fabrication procedures for the monolithic amplifier fabrication are presented and the results of measurements on a limited number of sample amplifiers are given.

  20. Class E/F switching power amplifiers

    NASA Technical Reports Server (NTRS)

    Hajimiri, Seyed-Ali (Inventor); Aoki, Ichiro (Inventor); Rutledge, David B. (Inventor); Kee, Scott David (Inventor)

    2004-01-01

    The present invention discloses a new family of switching amplifier classes called class E/F amplifiers. These amplifiers are generally characterized by their use of the zero-voltage-switching (ZVS) phase correction technique to eliminate of the loss normally associated with the inherent capacitance of the switching device as utilized in class-E amplifiers, together with a load network for improved voltage and current wave-shaping by presenting class-F.sup.-1 impedances at selected overtones and class-E impedances at the remaining overtones. The present invention discloses a several topologies and specific circuit implementations for achieving such performance.

  1. Log amplifier with pole-zero compensation

    DOEpatents

    Brookshier, W.

    1985-02-08

    A logarithmic amplifier circuit provides pole-zero compensation for improved stability and response time over 6-8 decades of input signal frequency. The amplifer circuit includes a first operational amplifier with a first feedback loop which includes a second, inverting operational amplifier in a second feedstock loop. The compensated output signal is provided by the second operational amplifier with the log elements, i.e., resistors, and the compensating capacitors in each of the feedback loops having equal values so that each break point is offset by a compensating break point or zero.

  2. Direct nuclear-pumped laser amplifier

    NASA Technical Reports Server (NTRS)

    Jalufka, N. W.

    1981-01-01

    A (He-3)-Xe gas mixture, excited by the He-3(n,p)H-3 reaction, has been employed to amplify the output of a (He-3)Xe direct nuclear-pumped laser. Lasing occurred at the 2.63 micron line of XeI in the oscillator. The oscillator output was reflected through 180 deg and passed through the amplifier system. Power measurements of the oscillator output and the amplifier output show the laser power to be amplified by a factor of 3 for the (He-3)-Xe system. Amplification by a factor of 5 was obtained for a (He-3)-CO system.

  3. Ping-pong auto-zero amplifier with glitch reduction

    SciTech Connect

    Larson, Mark R.

    2008-01-22

    A ping-pong amplifier with reduced glitching is described. The ping-pong amplifier includes a nulling amplifier coupled to a switching network. The switching network is used to auto-zero a ping amplifier within a ping-pong amplifier. The nulling amplifier drives the output of a ping amplifier to a proper output voltage level during auto-zeroing of the ping amplifier. By being at a proper output voltage level, glitches associated with transitioning between a ping amplifier and a pong amplifier are reduced or eliminated.

  4. Fiber networks amplify active stress.

    PubMed

    Ronceray, Pierre; Broedersz, Chase P; Lenz, Martin

    2016-03-15

    Large-scale force generation is essential for biological functions such as cell motility, embryonic development, and muscle contraction. In these processes, forces generated at the molecular level by motor proteins are transmitted by disordered fiber networks, resulting in large-scale active stresses. Although these fiber networks are well characterized macroscopically, this stress generation by microscopic active units is not well understood. Here we theoretically study force transmission in these networks. We find that collective fiber buckling in the vicinity of a local active unit results in a rectification of stress towards strongly amplified isotropic contraction. This stress amplification is reinforced by the networks' disordered nature, but saturates for high densities of active units. Our predictions are quantitatively consistent with experiments on reconstituted tissues and actomyosin networks and shed light on the role of the network microstructure in shaping active stresses in cells and tissue. PMID:26921325

  5. Hydraulically amplified PZT mems actuator

    DOEpatents

    Miles, Robin R.

    2004-11-02

    A hydraulically amplified microelectromechanical systems actuator. A piece of piezoelectric material or stacked piezo bimorph is bonded or deposited as a thin film. The piece is operatively connected to a primary membrane. A reservoir is operatively connected to the primary membrane. The reservoir contains a fluid. A membrane is operatively connected to the reservoir. In operation, energizing the piezoelectric material causing the piezoelectric material to bow. Bowing of the piezoelectric material causes movement of the primary membrane. Movement of the primary membrane results in a force in being transmitted to the liquid in the reservoir. The force in the liquid causes movement of the membrane. Movement of the membrane results in an operating actuator.

  6. Transverse pumped laser amplifier architecture

    DOEpatents

    Bayramian, Andrew James; Manes, Kenneth R.; Deri, Robert; Erlandson, Alvin; Caird, John; Spaeth, Mary L.

    2015-05-19

    An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.

  7. Transverse pumped laser amplifier architecture

    DOEpatents

    Bayramian, Andrew James; Manes, Kenneth; Deri, Robert; Erlandson, Al; Caird, John; Spaeth, Mary

    2013-07-09

    An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.

  8. CHARGE IMBALANCE

    SciTech Connect

    Clarke, John

    1980-09-01

    The purpose of this article is to review the theory of charge imbalance, and to discuss its relevance to a number of experimental situations. We introduce the concepts of quasiparticle charge and charge imbalance, and discuss the generation and detection of charge imbalance by tunneling. We describe the relaxation of the injected charge imbalance by inelastic scattering processes, and show how the Boltzmann equation can be solved to obtain the steady state quasiparticle distribution and the charge relaxation rate. Details are given of experiments to measure charge imbalance and the charge relaxation rate when inelastic scattering is the predominant relaxation mechanism. Experiments on and theories of other charge relaxation mechanisms are discussed, namely relaxation via elastic scattering in the presence of energy gap anisotropy, or in the presence of a pair breaking mechanism such as magnetic impurities or an applied supercurrent or magnetic field. We describe three other situations in which charge imbalance occurs, namely the resistance of the NS interface, phase slip centers, and the flow of a supercurrent in the presence of a temperature gradient.

  9. A high-power 95 GHz gyro-TWT amplifier

    SciTech Connect

    Kreischer, K.E.; Basten, M.; Blank, M.; Danly, B.G.; Guss, W.C.; Temkin, R.J.

    1992-07-01

    The need for radar systems with greater resolution has led to renewed interest in the development of efficient high-power amplifiers at 95 GHz. The gyro-TWT is capable of producing high power with the added attraction of having lower ohmic loading on the smooth fast-wave interaction circuit than conventional slow-wave sources. We have completed a comprehensive desip of a 95 GHz gyro-TWT amplifier that is capable of producing 120 kill of output power with an efficiency of 30%, a saturated gain of 38 dB and an instantaneous bandwidth of over 5 GHz. Our concept uses an annular beam produced by a MIG electron source and operates in the TE{sub 5,1} cylindrical waveguide mode. Realistic beam parameters from gun simulations were, included in our efficiency calculations. In addition, our design includes the use of a compact superconducting magnet, quasi-optical input and output couplers and a sever to supress oscillations. The overall mechanical design shows that a compact, lightweight amplifier with adequate beam clearance is possible. This report also includes a study of a gyro-TWT using a solid on-axis beam from a Pierce-wiggler electron source coupling with a TE{sub 1,n} waveguide mode. Nonlinear models indicated that an efficient interaction with the waveguide mode was possible, however, beam simulations indicated that the high current density beam had large internal space charge forces that caused a substantial degradation of the beam quality.

  10. A high-power 95 GHz gyro-TWT amplifier

    SciTech Connect

    Kreischer, K.E.; Basten, M.; Blank, M.; Danly, B.G.; Guss, W.C.; Temkin, R.J.

    1992-07-01

    The need for radar systems with greater resolution has led to renewed interest in the development of efficient high-power amplifiers at 95 GHz. The gyro-TWT is capable of producing high power with the added attraction of having lower ohmic loading on the smooth fast-wave interaction circuit than conventional slow-wave sources. We have completed a comprehensive desip of a 95 GHz gyro-TWT amplifier that is capable of producing 120 kill of output power with an efficiency of 30%, a saturated gain of 38 dB and an instantaneous bandwidth of over 5 GHz. Our concept uses an annular beam produced by a MIG electron source and operates in the TE[sub 5,1] cylindrical waveguide mode. Realistic beam parameters from gun simulations were, included in our efficiency calculations. In addition, our design includes the use of a compact superconducting magnet, quasi-optical input and output couplers and a sever to supress oscillations. The overall mechanical design shows that a compact, lightweight amplifier with adequate beam clearance is possible. This report also includes a study of a gyro-TWT using a solid on-axis beam from a Pierce-wiggler electron source coupling with a TE[sub 1,n] waveguide mode. Nonlinear models indicated that an efficient interaction with the waveguide mode was possible, however, beam simulations indicated that the high current density beam had large internal space charge forces that caused a substantial degradation of the beam quality.

  11. Self-consistent simulation of cyclotron autoresonance maser amplifiers

    SciTech Connect

    Pendergast, K.D.; Danly, B.G.; Temkin, R.J.; Wurtele, J.S.

    1988-04-01

    A self-consistent, one-dimensional model of the cyclotron autoresonance maser (CARM) amplifier is developed, and numerical simulations based on this model are described. Detailed studies of the CARM gain and efficiency for a wide range of initial energy and velocity spreads are presented. The interaction efficiency is found to be substantially increased when the axial magnetic field is tapered. For example, efficiencies of greater than 41 percent are obtained for a 140-GHz CARM amplifier with a tapered axial magnetic field and a 700-kV 4.5-A electron beam with parallel velocity spreads of less than 1 percent. A discussion of the nonlinear bandwidth and interaction sensitivity to axial field inhomogeneities is presented.

  12. Coulometer battery state-of-charge indicator

    NASA Technical Reports Server (NTRS)

    Birchenough, A. G.; Secunde, R.

    1970-01-01

    Mercury-column electrochemical coulometer is a linear ampere-hour integrating device consisting of a sealed glass tube containing two columns of mercury separated by a gap containing an electrolyte. The drive circuit uses operational amplifier techniques to match nonlinear charge-discharge characteristics of an alkaline battery.

  13. Fishing amplifies forage fish population collapses

    PubMed Central

    Essington, Timothy E.; Moriarty, Pamela E.; Froehlich, Halley E.; Hodgson, Emma E.; Koehn, Laura E.; Oken, Kiva L.; Siple, Margaret C.; Stawitz, Christine C.

    2015-01-01

    Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches. PMID:25848018

  14. Fishing amplifies forage fish population collapses.

    PubMed

    Essington, Timothy E; Moriarty, Pamela E; Froehlich, Halley E; Hodgson, Emma E; Koehn, Laura E; Oken, Kiva L; Siple, Margaret C; Stawitz, Christine C

    2015-05-26

    Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches. PMID:25848018

  15. Internal Charging

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.

    2014-01-01

    (1) High energy (>100keV) electrons penetrate spacecraft walls and accumulate in dielectrics or isolated conductors; (2) Threat environment is energetic electrons with sufficient flux to charge circuit boards, cable insulation, and ungrounded metal faster than charge can dissipate; (3) Accumulating charge density generates electric fields in excess of material breakdown strenght resulting in electrostatic discharge; and (4) System impact is material damage, discharge currents inside of spacecraft Faraday cage on or near critical circuitry, and RF noise.

  16. QIE: Performance Studies of the Next Generation Charge Integrator

    SciTech Connect

    Roy, T.; Yumiceva, F.; Hirschauer, J.; Freeman, J.; Hughes, E.; Hare, D.; Dal Monte, L.; Whitbeck, A.; Zimmerman, T.

    2015-02-06

    The Phase 1 upgrade of the Hadron Calorimeter (HCAL) in the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) will include two new generations (named QIE10 and QIE11) of the radiation-tolerant flash ADC chip known as the Charge Integrator and Encoder or QIE. The QIE integrates charge from a photo sensor over a 25 ns time period and encodes the result in a non-linear digital output while having a good sensitivity in both the higher and the lower energy values. The charge integrator has the advantage of analyzing fast signals coming from the calorimeters as long as the timing and pulse information is available. The calorimeters send fast, negative polarity signals, which the QIE integrates in its non-inverting input amplifier. The input analog signal enters the QIE chip through two points: signal and reference. The chip integrates the difference between these two values. This helps in getting rid of the incoming noise, which is effectively cancelled out in the difference. Over a period of about six months between September, 2013 and April, 2014 about 320 QIE10 and about 20 QIE11 chips were tested in Fermilab using a single-chip test stand where every individual chip was tested for its characteristic features using a clam-shell. The results of those tests performed on the QIE10 and QIE11 are summarized in this document.

  17. QIE: performance studies of the next generation charge integrator

    NASA Astrophysics Data System (ADS)

    Roy, T.; Yumiceva, F.; Hirschauer, J.; Freeman, J.; Hughes, E.; Hare, D.; Dal Monte, L.; Whitbeck, A.; Zimmerman, T.

    2015-02-01

    The Phase 1 upgrade of the Hadron Calorimeter (HCAL) in the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) will include two new generations (named QIE10 and QIE11) of the radiation-tolerant flash ADC chip known as the Charge Integrator and Encoder or QIE. The QIE integrates charge from a photo sensor over a 25 ns time period and encodes the result in a non-linear digital output while having a good sensitivity in both the higher and the lower energy values. The charge integrator has the advantage of analyzing fast signals coming from the calorimeters as long as the timing and pulse information is available. The calorimeters send fast, negative polarity signals, which the QIE integrates in its non-inverting input amplifier. The input analog signal enters the QIE chip through two points: signal and reference. The chip integrates the difference between these two values. This helps in getting rid of the incoming noise, which is effectively cancelled out in the difference. Over a period of about six months between September, 2013 and April, 2014 about 320 QIE10 and about 20 QIE11 chips were tested in Fermilab using a single-chip test stand where every individual chip was tested for its characteristic features using a clam-shell. The results of those tests performed on the QIE10 and QIE11 are summarized in this document.

  18. Method for reducing snap in magnetic amplifiers

    NASA Technical Reports Server (NTRS)

    Fischer, R. L. E.; Word, J. L.

    1968-01-01

    Method of reducing snap in magnetic amplifiers uses a degenerative feedback circuit consisting of a resistor and a separate winding on a magnetic core. The feedback circuit extends amplifier range by allowing it to be used at lower values of output current.

  19. Integrated-circuit balanced parametric amplifier

    NASA Technical Reports Server (NTRS)

    Dickens, L. E.

    1975-01-01

    Amplifier, fabricated on single dielectric substrate, has pair of Schottky barrier varactor diodes mounted on single semiconductor chip. Circuit includes microstrip transmission line and slot line section to conduct signals. Main features of amplifier are reduced noise output and low production cost.

  20. Direct solar-pumped iodine laser amplifier

    NASA Technical Reports Server (NTRS)

    Han, K. S.

    1986-01-01

    During this period the parametric studies of the iodine laser oscillator pumped by a Vortek simulator were carried out before amplifier studies. The amplifier studies are postponed to the extended period after completing the parametric studies. In addition, the kinetic modeling of a solar-pumped iodine laser amplifier, and the experimental work for a solar pumped dye laser amplifier are in progress. This report contains three parts: (1) a 10 W CW iodine laser pumped by a Vortek solar simulator; (2) kinetic modeling to predict the time to lasing threshold, lasing time, and energy output of solar-pumped iodine laser; and (3) the study of the dye laser amplifier pumped by a Tamarack solar simulator.

  1. Design and performance of the beamlet amplifiers

    SciTech Connect

    Erlandson, A.C.; Rotter, M.D.; Frank, M.D.; McCracken, R.W.

    1996-06-01

    In future laser systems, such as the National Ignition Facility (NIF), multi-segment amplifiers (MSAs) will be used to amplify the laser beam to the required levels. As a prototype of such a laser architecture, the authors have designed, built, and tested flash-lamp-pumped, Nd:Glass, Brewster-angle slab MSAs for the Beamlet project. In this article, they review the fundamentals of Nd:Glass amplifiers, describe the MSA geometry, discuss parameters that are important in amplifier design, and present our results on the characterization of the Beamlet MSAs. In particular, gain and beam steering measurements show that the Beamlet amplifiers meet all optical performance specifications and perform close to model predictions.

  2. Dual-range linearized transimpedance amplifier system

    DOEpatents

    Wessendorf, Kurt O.

    2010-11-02

    A transimpedance amplifier system is disclosed which simultaneously generates a low-gain output signal and a high-gain output signal from an input current signal using a single transimpedance amplifier having two different feedback loops with different amplification factors to generate two different output voltage signals. One of the feedback loops includes a resistor, and the other feedback loop includes another resistor in series with one or more diodes. The transimpedance amplifier system includes a signal linearizer to linearize one or both of the low- and high-gain output signals by scaling and adding the two output voltage signals from the transimpedance amplifier. The signal linearizer can be formed either as an analog device using one or two summing amplifiers, or alternately can be formed as a digital device using two analog-to-digital converters and a digital signal processor (e.g. a microprocessor or a computer).

  3. Post pulse shutter for laser amplifier

    DOEpatents

    Bradley, L.P.; Carder, B.M.; Gagnon, W.L.

    1981-03-17

    Disclosed are an apparatus and method for quickly closing off the return path for an amplified laser pulse at the output of an amplifier so as to prevent damage to amplifiers and other optical components appearing earlier in the chain by the return of an amplified pulse. The apparatus consists of a fast retropulse or post pulse shutter to suppress target reflection and/or beam return. This is accomplished by either quickly placing a solid across the light transmitting aperture of a component in the chain, such as a spatial filter pinhole, or generating and directing a plasma with sufficiently high density across the aperture, so as to, in effect, close the aperture to the returning amplified energy pulse. 13 figs.

  4. Post pulse shutter for laser amplifier

    DOEpatents

    Bradley, Laird P. [Livermore, CA; Carder, Bruce M. [Antioch, CA; Gagnon, William L. [Berkeley, CA

    1981-03-17

    Apparatus and method for quickly closing off the return path for an amplified laser pulse at the output of an amplifier so as to prevent damage to amplifiers and other optical components appearing earlier in the chain by the return of an amplified pulse. The apparatus consists of a fast retropulse or post pulse shutter to suppress target reflection and/or beam return. This is accomplished by either quickly placing a solid across the light transmitting aperture of a component in the chain, such as a spatial filter pinhole, or generating and directing a plasma with sufficiently high density across the aperture, so as to, in effect, close the aperture to the returning amplified energy pulse.

  5. Qubit readout with a directional parametric amplifier

    NASA Astrophysics Data System (ADS)

    Sliwa, K. M.; Abdo, B.; Narla, A.; Shankar, S.; Hatridge, M.; Frunzio, L.; Schoelkopf, R. J.; Devoret, M. H.

    2014-03-01

    Josephson junction based quantum limited parametric amplifiers play an essential role in superconducting qubit measurements. These measurements necessitate circulators and isolators between the amplifier and qubit to add directionality and/or isolation. Unfortunately, this extra hardware limits both quantum measurement efficiency and experimental scalability. Here we present a quantum-limited Josephson-junction-based directional amplifier (JDA) based on a novel coupling between two nominally identical Josephson parametric converters (JPCs). The device achieves a forward gain of 11 dB with a 15 MHz dynamical bandwidth, but higher gains are possible at the expense of bandwidth. We also present measurements of a transmon qubit made with the JDA, and show minimal measurement back-action despite the absence of any isolator or circulator before the amplifier. These results provide a first step toward realizing on-chip integration of qubits and parametric amplifiers. Work supported by: IARPA, ARO, and NSF.

  6. mm-wave solid state amplifiers

    NASA Astrophysics Data System (ADS)

    Wolfert, P. H.; Crowley, J. D.; Fank, F. B.

    The development of mm-wave amplifiers using InP Gunn diodes is reviewed including a low-noise eight-stage amplifier for replacement of a Ka-band TWTA and a three-stage amplifier for the 42.5 to 44.5 range with an output power of 100 mW and 20 dB associated gain. A detailed description of a three-stage amplifier for the 54 to 58 GHz range is given with 100 mW output power and 15 dB associated gain, a small signal gain of 30 dB and an N.F. of 15.5 to 16.5 dB. The design of a broad band, low-loss V-band circulator, which was used in the amplifier, is described.

  7. Ultrafast laser and amplifier sources

    NASA Astrophysics Data System (ADS)

    Rundquist, A.; Durfee, C.; Chang, Z.; Taft, G.; Zeek, E.; Backus, S.; Murnane, M. M.; Kapteyn, H. C.; Christov, I.; Stoev, V.

    1997-08-01

    There has been remarkable progress in the development of high peak-power ultrafast lasers in recent years. Lasers capable of generating terawatt peak powers with unprecedented short pulse durations can now be built on a single optical table in a small laboratory. The rapid technological progress has made possible a host of new scientific advances in high-field science, such as the generation of coherent femtosecond X-ray pulses, and the generation of MeV-energy electron beams and high-energy ions. In this paper, we review progress in the development and design of ultrafast high-power lasers based on Ti:sapphire, including the ultrafast laser oscillators that are a very important enabling technology for high-power ultrafast systems, and ultrafast amplified laser systems that generate 20 fs duration pulses with several watts average power at kilohertz repetition-rates. Ultrafast waveform measurements of these pulses demonstrate that such short pulses can be generated with high fidelity. Finally, we discuss applications of ultrafast high-power pulses, including the generation of femtosecond to attosecond X-ray pulses.

  8. Fiber networks amplify active stress

    NASA Astrophysics Data System (ADS)

    Lenz, Martin; Ronceray, Pierre; Broedersz, Chase

    Large-scale force generation is essential for biological functions such as cell motility, embryonic development, and muscle contraction. In these processes, forces generated at the molecular level by motor proteins are transmitted by disordered fiber networks, resulting in large-scale active stresses. While fiber networks are well characterized macroscopically, this stress generation by microscopic active units is not well understood. I will present a comprehensive theoretical study of force transmission in these networks. I will show that the linear, small-force response of the networks is remarkably simple, as the macroscopic active stress depends only on the geometry of the force-exerting unit. In contrast, as non-linear buckling occurs around these units, local active forces are rectified towards isotropic contraction and strongly amplified. This stress amplification is reinforced by the networks' disordered nature, but saturates for high densities of active units. I will show that our predictions are quantitatively consistent with experiments on reconstituted tissues and actomyosin networks, and that they shed light on the role of the network microstructure in shaping active stresses in cells and tissue.

  9. Multi-pass light amplifier

    NASA Technical Reports Server (NTRS)

    Plaessmann, Henry (Inventor); Grossman, William M. (Inventor)

    1997-01-01

    A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A confocal resonator or White Cell resonator is provided, including two or three curvilinearly shaped mirrors facing each other along a resonator axis and an optical gain medium positioned on the resonator axis between the mirrors (confocal resonator) or adjacent to one of the mirrors (White Cell). In a first embodiment, two mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator. The optical gain medium may be solid-state, liquid or gaseous medium and may be pumped longitudinally or transversely. In a second embodiment, first and second mirrors face a third mirror in a White Cell configuration, and the optical gain medium is positioned at or adjacent to one of the mirrors. Defocusing means and optical gain medium cooling means are optionally provided with either embodiment, to controllably defocus the light beam, to cool the optical gain medium and to suppress thermal lensing in the gain medium.

  10. Charging machine

    DOEpatents

    Medlin, John B.

    1976-05-25

    A charging machine for loading fuel slugs into the process tubes of a nuclear reactor includes a tubular housing connected to the process tube, a charging trough connected to the other end of the tubular housing, a device for loading the charging trough with a group of fuel slugs, means for equalizing the coolant pressure in the charging trough with the pressure in the process tubes, means for pushing the group of fuel slugs into the process tube and a latch and a seal engaging the last object in the group of fuel slugs to prevent the fuel slugs from being ejected from the process tube when the pusher is removed and to prevent pressure liquid from entering the charging machine.

  11. On a theory of an FEL amplifier with circular waveguide and guiding magnetic field

    SciTech Connect

    Saldin, E.L.; Schneidmiller, E.A.; Yurkov, M.V.

    1995-12-31

    We consider an FEL amplifier with an axisymmetric electron beam, circular waveguide, helical undulator and guiding magnetic field. The presented nonlinear theory of the FEL amplifier is based on Hamiltonian description of particle motion and radiation field representation with Green function method. The space charge fields, energy spread and diffraction effects are taken into consideration. Such an FEL amplifier configuration possesses some peculiarities when it operates in a regime with the negative longitudinal mass (i.e. when{mu}{sup -1}{proportional_to}dv{sub z}/dE < 0). It is shown that in the presence of strong space charge fields, the so-called {open_quotes}negative mass{close_quotes} instability may influence significantly on the FEL amplifier operation resulting in a significant increase in the FEL amplifier efficiency. It is proposed in the presented paper to use the effect of the {open_quotes}negative mass instability{close_quotes} to achieve an effective bunching of the CERN Linear Collider (LIC) driving beam.

  12. Event-driven charge-coupled device design and applications therefor

    NASA Technical Reports Server (NTRS)

    Doty, John P. (Inventor); Ricker, Jr., George R. (Inventor); Burke, Barry E. (Inventor); Prigozhin, Gregory Y. (Inventor)

    2005-01-01

    An event-driven X-ray CCD imager device uses a floating-gate amplifier or other non-destructive readout device to non-destructively sense a charge level in a charge packet associated with a pixel. The output of the floating-gate amplifier is used to identify each pixel that has a charge level above a predetermined threshold. If the charge level is above a predetermined threshold the charge in the triggering charge packet and in the charge packets from neighboring pixels need to be measured accurately. A charge delay register is included in the event-driven X-ray CCD imager device to enable recovery of the charge packets from neighboring pixels for accurate measurement. When a charge packet reaches the end of the charge delay register, control logic either dumps the charge packet, or steers the charge packet to a charge FIFO to preserve it if the charge packet is determined to be a packet that needs accurate measurement. A floating-diffusion amplifier or other low-noise output stage device, which converts charge level to a voltage level with high precision, provides final measurement of the charge packets. The voltage level is eventually digitized by a high linearity ADC.

  13. Applications of Kinetic Inductance: Parametric Amplifier & Phase Shifter, 2DEG Coupled Co-planar Structures & Microstrip to Slotline Transition at RF Frequencies

    NASA Astrophysics Data System (ADS)

    Surdi, Harshad

    Kinetic inductance springs from the inertia of charged mobile carriers in alternating electric fields and it is fundamentally different from the magnetic inductance which is only a geometry dependent property. The magnetic inductance is proportional to the volume occupied by the electric and magnetic fields and is often limited by the number of turns of the coil. Kinetic inductance on the other hand is inversely proportional to the density of electrons or holes that exert inertia, the unit mass of the charge carriers and the momentum relaxation time of these charge carriers, all of which can be varied merely by modifying the material properties. Highly sensitive and broadband signal amplifiers often broaden the field of study in astrophysics. Quantum-noise limited travelling wave kinetic inductance parametric amplifiers offer a noise figure of around 0.5 K +/- 0.3 K as compared to 20 K in HEMT signal amplifiers and can be designed to operate to cover the entire W-band (75 GHz -- 115 GHz). The research cumulating to this thesis involves applying and exploiting kinetic inductance properties in designing a W-band orthogonal mode transducer, quadratic gain phase shifter with a gain of ~49 dB over a meter of microstrip transmission line. The phase shifter will help in measuring the maximum amount of phase shift Deltaφmax(I) that can be obtained from half a meter transmission line which helps in predicting the gain of a travelling wave parametric amplifier. In another project, a microstrip to slot line transition is designed and optimized to operate at 150 GHz and 220 GHz frequencies, that is used as a part of horn antenna coupled microwave kinetic inductance detector proposed to operate from 138 GHz to 250 GHz. In the final project, kinetic inductance in a 2D electron gas (2DEG) is explored by design, simulation, fabrication and experimentation. A transmission line model of a 2DEG proposed by Burke (1999), is simulated and verified experimentally by fabricating a

  14. Semiconductor optical amplifiers and Raman amplification for 1310-nm dense wavelength division multiplexed transmission

    NASA Astrophysics Data System (ADS)

    Mazurek, Paweł; Czyżak, Paweł; de Waardt, Huug; Turkiewicz, Jarosław Piotr

    2015-11-01

    We investigate the utilization of semiconductor optical amplifiers (SOAs) and quantum-dot laser-based Raman amplifiers in high-capacity dense wavelength division multiplexed (DWDM) 1310-nm transmission systems. Performed simulations showed that in a 10×40 Gbit/s system, the utilization of a single Raman amplifier in a back-propagation scheme can extend the maximum error-free (bit error rate <10-9) transmission distance by approximately 25 km in comparison with the same system utilizing only an SOA used as a preamplifier. We successfully applied a Raman amplifier in an 8×2×40 Gbit/s 1310-nm polarization multiplexed (PolMux) DWDM transmission over 25 km. Conducted experiments showed that the utilization of a Raman amplifier in this system leads to 4-dB improvement of the average channel sensitivity in comparison to the same system utilizing SOAs. This sensitivity improvement can be translated into a higher power budget. Moreover, lower input optical power in a system utilizing a Raman amplifier reduces the four-wave mixing interactions. The obtained results prove that Raman amplification can be successfully applied in 1310-nm high-capacity transmission systems, e.g., to extend the reach of 400G and 1T Ethernet systems.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. High power Ka band TWT amplifier

    SciTech Connect

    Golkowski, C.; Ivers, J.D.; Nation, J.A.; Wang, P.; Schachter, L.

    1999-07-01

    Two high power 35 GHz TWT amplifiers driven by a relativistic pencil, 850 kV, 200A electron beam have been assembled and tested. The first had a dielectric slow wave structure and was primarily used to develop diagnostics, and to gain experience in working with high power systems in Ka band. The source of the input power for the amplifier was a magnetron producing a 30 kW, 200ns long pulse of which 10 kW as delivered to the experiment. The 30 cm long dielectric (Teflon) amplifier produced output power levels of about 1 MW with a gain of about 23 dB. These results are consistent with expectations from PIC code simulations for this arrangement. The second amplifier, which is a single stage disk loaded slow wave structure, has been designed. It consists of one hundred uniform cells with two sets of ten tapered calls at the ends to lower the reflection coefficient. The phase advance per cell is {pi}/2. The amplifier passband extends from 28 to 40 GHz. It is designed to increase the output power to about 20 MW. The amplifier is in construction and will be tested in the near future. Details of the design of both systems will be provided and initial results from the new amplifier presented.

  17. A Low-Noise Semiconductor Optical Amplifier

    SciTech Connect

    Ratowsky, R.P.; Dijaili, S.; Kallman, J.S.; Feit, M.D.; Walker, J.

    1999-03-23

    Optical amplifiers are essential devices for optical networks, optical systems, and computer communications. These amplifiers compensate for the inevitable optical loss in long-distance propagation (>50 km) or splitting (>10x). Fiber amplifiers such as the erbium-doped fiber amplifier have revolutionized the fiber-optics industry and are enjoying widespread use. Semiconductor optical amplifiers (SOAs) are an alternative technology that complements the fiber amplifiers in cost and performance. One obstacle to the widespread use of SOAs is the severity of the inevitable noise output resulting from amplified spontaneous emission (ASE). Spectral filtering is often used to reduce ASE noise, but this constrains the source spectrally, and improvement is typically limited to about 10 dB. The extra components also add cost and complexity to the final assembly. The goal of this project was to analyze, design, and take significant steps toward the realization of an innovative, low-noise SOA based on the concept of ''distributed spatial filtering'' (DSF). In DSF, we alternate active SOA segments with passive free-space diffraction regions. Since spontaneous emission radiates equally in all directions, the free-space region lengthens the amplifier for a given length of gain region, narrowing the solid angle into which the spontaneous emission is amplified [1,2]. Our innovation is to use spatial filtering in a differential manner across many segments, thereby enhancing the effect when wave-optical effects are included [3]. The structure quickly and effectively strips the ASE into the higher-order modes, quenching the ASE gain relative to the signal.

  18. Cascaded transformerless DC-DC voltage amplifier with optically isolated switching devices

    NASA Technical Reports Server (NTRS)

    Sridharan, Govind (Inventor)

    1993-01-01

    A very high voltage amplifier is provided in which plural cascaded banks of capacitors are switched by optically isolated control switches so as to be charged in parallel from the preceding stage or capacitor bank and to discharge in series to the succeeding stage or capacitor bank in alternating control cycles. The optically isolated control switches are controlled by a logic controller whose power supply is virtually immune to interference from the very high voltage output of the amplifier by the optical isolation provided by the switches, so that a very high voltage amplification ratio may be attained using many capacitor banks in cascade.

  19. Low Noise Amplifiers and Receivers for Remote Sensing

    NASA Technical Reports Server (NTRS)

    Kangaslahti, Pekka; Lim, Boon; Gaier, Todd; Tanner, Alan; Varonen, Mikko; Samoska, Lorene; Brown, Shannon; Lambrigtsen, Bjorn; Reising, Steven; Tanabe, Jordan; Montes, Oliver; Dawson, Douglas; Parashare, Chaitali

    2011-01-01

    The study of atmospheric dynamics and climatology depend on accurate and frequent measurements of temperature and humidity profiles of the atmosphere. These measurements furthermore enable highly accurate measurements of ocean topography by providing total column water vapour data for radar path delay correction. The atmospheric temperature profile is characterised at the oxygen molecule absorption frequencies (60 and 118 GHz) and the humidity profile at the water molecule absorption frequencies (23 and 183 GHz). Total column measurements can be achieved by comparing measured radiometric temperatures at atmospheric window channels, such as 90, 130 and 166 GHz. The standard receiver technology for these frequencies was diode mixers with MMIC LNAs being applied at the lower frequencies. The sensitivity of millimetre wave receivers improved significantly with the introduction of the low noise 35 nm gate length InP MMIC amplifiers. We currently achieve 3 dB noise figure at 180 GHz and 2 dB noise figure at 90 GHz with our MMIC low noise amplifiers (LNAs) in room temperature. These amplifiers and the receivers we have built using them made it possible to conduct highly accurate airborne measurement campaigns from the Global Hawk unmanned aerial vehicle, develop millimeter wave internally calibrated radiometers for altimeter radar path delay correction, and build prototypes of large arrays of millimeter receivers for a geostationary interferometric sounder. We use the developed millimeter wave receivers to measure temperature and humidity profiles in the atmosphere and in hurricanes as well as to characterize the path delay error in ocean topography altimetry.

  20. Low Noise Amplifiers and Receivers for Remote Sensing

    NASA Technical Reports Server (NTRS)

    Kangaslahti, Pekka; Lim, Boon; Gaier, Todd; Tanner, Alan; Varonen, Mikko; Samoska, Lorene; Brown, Shannon; Lambrigsten, Bjorn; Reising, Steven; Tanabe, Jordan; Montes, Oliver; Dawson, Douglas; Parashare, Chaitali

    2012-01-01

    The study of atmospheric dynamics and climatology depend on accurate and frequent measurements of temperature and humidity profiles of the atmosphere. These measurements furthermore enable highly accurate measurements of ocean topography by providing total column water vapour data for radar path delay correction. The atmospheric temperature profile is characterized at the oxygen molecule absorption frequencies (60 and 118 GHz) and the humidity profile at the water molecule absorption frequencies (23 and 183 GHz). Total column measurements can be achieved by comparing measured radiometric temperatures at atmospheric window channels, such as 90, 130, and 166 GHz. The standard receiver technology for these frequencies was diode mixers with MMIC LNAs being applied at the lower frequencies. The sensitivity of millimeter wave receivers improved significantly with the introduction of the low noise 35 nm gate length InP MMIC amplifiers. We currently achieve 3 dB noise figure at 180 GHz and 2 dB noise figure at 90 GHz with our MMIC low noise amplifiers (LNAs) in room temperature. These amplifiers and the receivers we have built using them made it possible to conduct highly accurate airborne measurements campaigns from the Global Hawk unmanned aerial vehicle, develop millimeter wave internally calibrated radiometers for altimeter radar path delay correction, and build prototypes of large arrays of millimeter receivers for a geostationary interferometric sounder. We use the developed millimeter wave receivers to measure temperature and humidity profiles in the atmosphere and in hurricanes as well as to characterize the path delay error in ocean topography alitmetery.

  1. Fiber optical parametric amplifiers in optical communication systems

    PubMed Central

    Marhic (†), Michel E; Andrekson, Peter A; Petropoulos, Periklis; Radic, Stojan; Peucheret, Christophe; Jazayerifar, Mahmoud

    2015-01-01

    The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time-division multiplexed formats. High-quality mid-span spectral inversion has been demonstrated at 0.64 Tb/s, avoiding electronic dispersion compensation. All-optical amplitude regeneration of amplitude-modulated signals has been performed, while PSAs have been used to demonstrate phase regeneration of phase-modulated signals. A PSA with 1.1-dB noise figure has been demonstrated, and preliminary wavelength-division multiplexing experiments have been performed with PSAs. 512 Gb/s have been transmitted over 6,000 km by periodic phase conjugation. Simulations indicate that PIAs could reach data rate x reach products in excess of 14,000 Tb/s × km in realistic wavelength-division multiplexed long-haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long-haul communication networks are discussed. PMID:25866588

  2. Squeezing with a flux-driven Josephson parametric amplifier

    NASA Astrophysics Data System (ADS)

    Menzel, E. P.; Zhong, L.; Eder, P.; Baust, A.; Haeberlein, M.; Hoffmann, E.; Deppe, F.; Marx, A.; Gross, R.; di Candia, R.; Solano, E.; Ihmig, M.; Inomata, K.; Yamamoto, T.; Nakamura, Y.

    2014-03-01

    Josephson parametric amplifiers (JPA) are promising devices for the implementation of continuous-variable quantum communication protocols. Operated in the phase-sensitive mode, they allow for amplifying a single quadrature of the electromagnetic field without adding any noise. While in practice internal losses introduce a finite amount of noise, our device still adds less noise than an ideal phase-insensitive amplifier. This property is a prerequisite for the generation of squeezed states. In this work, we reconstruct the Wigner function of squeezed vacuum, squeezed thermal and squeezed coherent states with our dual-path method [L. Zhong et al. arXiv:1307.7285 (2013); E. P. Menzel et al. Phys. Rev. Lett. 105 100401 (2010)]. In addition, we illuminate the physics of squeezed coherent microwave fields. This work is supported by SFB 631, German Excellence Initiative via NIM, EU projects SOLID, CCQED, PROMISCE and SCALEQIT, MEXT Kakenhi ``Quantum Cybernetics,'' JSPS FIRST Program, the NICT Commissioned Research, Basque Government IT472-10, Spanish MINECO FIS2012-36673-C03-02, and UPV/EHU UFI 11/55.

  3. Very high gain Nd:YLF amplifiers

    SciTech Connect

    Knights, M.G.; Thomas, M.D.; Chicklis, E.P.; Rines, G.A.; Seka, W.

    1988-05-01

    The authors report on high gain Nd:YLF rod amplifiers in which single-pass, small signal gains of over 1700 have been obtained along with stored energy densitiesgreater than or equal to0.4J/cm/sup 3/. The ability of Nd:YLF amplifiers to support such gains is a result of high parasitic oscillation thresholds, due primarily to the low refractive index of the material. These results suggest that Nd:YLF is an excellent candidate for amplifiers where high specific stored energies and/or very high gains are required.

  4. Achieving and maintaining cleanliness in NIF amplifiers

    SciTech Connect

    Burnham, A. K.; Horvath, J. A.; Letts, S. A.; Menapace, J. A.; Stowers, I. F.

    1998-07-28

    Cleanliness measurements made on AMPLAB prototype National Ignition Facility (NIF) laser amplifiers during assembly, cassette transfer, and amplifier operation are summarized. These measurements include particle counts from surface cleanliness assessments using filter swipe techniques and from airborne particle monitoring. Results are compared with similar measurements made on the Beamlet and Nova lasers and in flashlamp test fixtures. Observations of Class 100,000 aerosols after flashlamp firings are discussed. Comparisons are made between typical damage densities on laser amplifier optics from Novette, NOVA, Beamlet, and AMPLAB.

  5. High Efficiency Microwave Power Amplifier (HEMPA) Design

    NASA Technical Reports Server (NTRS)

    Sims, W. Herbert

    2004-01-01

    This paper will focus on developing an exotic switching technique that enhances the DC-to-RF conversion efficiency of microwave power amplifiers. For years, switching techniques implemented in the 10 kHz to 30 MHz region have resulted in DC-to-RF conversion efficiencies of 90-95-percent. Currently amplifier conversion efficiency, in the 2-3 GHz region approaches, 10-20-percent. Using a combination of analytical modeling and hardware testing, a High Efficiency Microwave Power Amplifier was built that demonstrated conversion efficiencies four to five times higher than current state of the art.

  6. The 60 GHz solid state power amplifier

    NASA Technical Reports Server (NTRS)

    Mcclymonds, J.

    1991-01-01

    A new amplifier architecture was developed during this contract that is superior to any other solid state approach. The amplifier produced 6 watts with 4 percent efficiency over a 2 GHz band at 61.5 GHz. The unit was 7 x 9 x 3 inches in size, 5.5 pounds in weight, and the conduction cooling through the baseplate is suitable for use in space. The amplifier used high efficiency GaAs IMPATT diodes which were mounted in 1-diode circuits, called modules. Eighteen modules were used in the design, and power combining was accomplished with a proprietary passive component called a combiner plate.

  7. Phase noise in RF and microwave amplifiers.

    PubMed

    Boudot, Rodolphe; Rubiola, Enrico

    2012-12-01

    Understanding amplifier phase noise is a critical issue in many fields of engineering and physics, such as oscillators, frequency synthesis, telecommunication, radar, and spectroscopy; in the emerging domain of microwave photonics; and in exotic fields, such as radio astronomy, particle accelerators, etc. Focusing on the two main types of base noise in amplifiers, white and flicker, the power spectral density of the random phase φ(t) is Sφ(f) = b(0) + b(-1)/f. White phase noise results from adding white noise to the RF spectrum in the carrier region. For a given RF noise level, b(0) is proportional to the reciprocal of the carrier power P(0). By contrast, flicker results from a near-dc 1/f noise-present in all electronic devices-which modulates the carrier through some parametric effect in the semiconductor. Thus, b(-1) is a parameter of the amplifier, constant in a wide range of P(0). The consequences are the following: Connecting m equal amplifiers in parallel, b(-1) is 1/m times that of one device. Cascading m equal amplifiers, b(-1) is m times that of one amplifier. Recirculating the signal in an amplifier so that the gain increases by a power of m (a factor of m in decibels) as a result of positive feedback (regeneration), we find that b(-1) is m(2) times that of the amplifier alone. The feedforward amplifier exhibits extremely low b(-1) because the carrier is ideally nulled at the input of its internal error amplifier. Starting with an extensive review of the literature, this article introduces a system-oriented model which describes the phase flickering. Several amplifier architectures (cascaded, parallel, etc.) are analyzed systematically, deriving the phase noise from the general model. There follow numerous measurements of amplifiers using different technologies, including some old samples, and in a wide frequency range (HF to microwaves), which validate the theory. In turn, theory and results provide design guidelines and give suggestions for CAD and

  8. Can Like Charges Attract Each Other?

    ERIC Educational Resources Information Center

    Balta, Nuri

    2012-01-01

    Electroscopes are sensitive instruments useful for investigations of static electricity. They are devices that are used for detecting whether an object is charged or uncharged. They also determine the type of charge. Their operation is based on the principle of like sign charge repulsion.

  9. Electrostatics with Computer-Interfaced Charge Sensors

    ERIC Educational Resources Information Center

    Morse, Robert A.

    2006-01-01

    Computer interfaced electrostatic charge sensors allow both qualitative and quantitative measurements of electrostatic charge but are quite sensitive to charges accumulating on modern synthetic materials. They need to be used with care so that students can correctly interpret their measurements. This paper describes the operation of the sensors,…

  10. Noise in phase-preserving linear amplifiers

    SciTech Connect

    Pandey, Shashank; Jiang, Zhang; Combes, Joshua; Caves, Carlton M.

    2014-12-04

    The purpose of a phase-preserving linear amplifier is to make a small signal larger, so that it can be perceived by instruments incapable of resolving the original signal, while sacrificing as little as possible in signal-to-noise. Quantum mechanics limits how well this can be done: the noise added by the amplifier, referred to the input, must be at least half a quantum at the operating frequency. This well-known quantum limit only constrains the second moments of the added noise. Here we provide the quantum constraints on the entire distribution of added noise: any phasepreserving linear amplifier is equivalent to a parametric amplifier with a physical state σ for the ancillary mode; σ determines the properties of the added noise.

  11. Advanced Concepts in Josephson Junction Reflection Amplifiers

    NASA Astrophysics Data System (ADS)

    Lähteenmäki, Pasi; Vesterinen, Visa; Hassel, Juha; Paraoanu, G. S.; Seppä, Heikki; Hakonen, Pertti

    2014-06-01

    Low-noise amplification at microwave frequencies has become increasingly important for the research related to superconducting qubits and nanoelectromechanical systems. The fundamental limit of added noise by a phase-preserving amplifier is the standard quantum limit, often expressed as noise temperature . Towards the goal of the quantum limit, we have developed an amplifier based on intrinsic negative resistance of a selectively damped Josephson junction. Here we present measurement results on previously proposed wide-band microwave amplification and discuss the challenges for improvements on the existing designs. We have also studied flux-pumped metamaterial-based parametric amplifiers, whose operating frequency can be widely tuned by external DC-flux, and demonstrate operation at pumping, in contrast to the typical metamaterial amplifiers pumped via signal lines at.

  12. Ku band low noise parametric amplifier

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A low noise, K sub u-band, parametric amplifier (paramp) was developed. The unit is a spacecraft-qualifiable, prototype, parametric amplifier for eventual application in the shuttle orbiter. The amplifier was required to have a noise temperature of less than 150 K. A noise temperature of less than 120 K at a gain level of 17 db was achieved. A 3-db bandwidth in excess of 350 MHz was attained, while deviation from phase linearity of about + or - 1 degree over 50 MHz was achieved. The paramp operates within specification over an ambient temperature range of -5 C to +50 C. The performance requirements and the operation of the K sub u-band parametric amplifier system are described. The final test results are also given.

  13. High dynamic range Josephson parametric amplifiers

    NASA Astrophysics Data System (ADS)

    Roch, Nicolas; Murch, Kater W.; Vijay, Rajamani

    Josephson parametric amplifiers (JPAs) have become the technology of choice to amplify small amplitude microwave signals since they show noise performances close to the quantum limit of amplification. An important challenge that faces this technology is the low dynamic range of current devices, which limits the number of measurements that can be performed concurrently and the rate of information acquisition for single measurements. We have fabricated and tested novel parametric amplifiers based on arrays of up to 100 SQUIDS. The amplifiers produce gain in excess of 20 dB over a large bandwidth and match the dynamic range achieved with traveling wave devices. Compared to the latter devices they are fabricated in a single lithography step and we will show that their bandwidth performance can be further extended using a recently developed impedance matching technique.

  14. Operational Amplifier Experiments for the Chemistry Laboratory.

    ERIC Educational Resources Information Center

    Braun, Robert D.

    1996-01-01

    Provides details of experiments that deal with the use of operational amplifiers and are part of a course in instrumental analysis. These experiments are performed after the completion of a set of electricity and electronics experiments. (DDR)

  15. Cryogenic Amplifier Based Receivers at Submillimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Goutam; Reck, Theodore and; Schlecht, Erich; Lin, Robert; Deal, William

    2012-01-01

    The operating frequency of InP high electron mobility transistor (HEMT) based amplifiers has moved well in the submillimeter-wave frequencies over the last couple of years. Working amplifiers with usable gain in waveguide packages has been reported beyond 700 GHz. When cooled cryogenically, they have shown substantial improvement in their noise temperature. This has opened up the real possibility of cryogenic amplifier based heterodyne receivers at submillimeter wavelengths for ground-based, air-borne, and space-based instruments for astrophysics, planetary, and Earth science applications. This paper provides an overview of the science applications at submillimeter wavelengths that will benefit from this technology. It also describes the current state of the InP HEMT based cryogenic amplifier receivers at submillimeter wavelengths.

  16. How to characterize the nonlinear amplifier?

    NASA Technical Reports Server (NTRS)

    Kallistratova, Dmitri Kouznetsov; Cotera, Carlos Flores

    1994-01-01

    The conception of the amplification of the coherent field is formulated. The definition of the coefficient of the amplification as the relation between the mean value of the field at the output to the value at the input and the definition of the noise as the difference between the number of photons in the output mode and square of the modulus of the mean value of the output amplitude are considered. Using a simple example it is shown that by these definitions the noise of the nonlinear amplifier may be less than the noise of the ideal linear amplifier of the same amplification coefficient. Proposals to search another definition of basic parameters of the nonlinear amplifiers are discussed. This definition should enable us to formulate the universal fundamental lower limit of the noise which should be valid for linear quantum amplifiers as for nonlinear ones.

  17. Two-stage hybrid microcircuit amplifier

    SciTech Connect

    Pyo, M.L.

    1987-04-01

    This report documents the design, development, and fabrication of a two-stage amplifier operating at 400 to 600 MHz. Included are characterization data, predictions generated during design, and measured performance.

  18. High Bandwidth Differential Amplifier for Shock Experiments

    SciTech Connect

    Ross, P., Tran, V., Chau, R.

    2012-10-01

    We developed a high bandwidth differential amplifier for gas gun shock experiments. The circuit has a bandwidth up to 1 GHz, and is capable of measuring signals of ≤1.5 V with a common mode rejection of 250 V. Conductivity measurements of gas gun targets are measured by flowing high currents through the targets. The voltage is measured across the target using a technique similar to a four-point probe. Because of the design of the current source and load, the target voltage is approximately 250 V relative to ground. Since the expected voltage change in the target is < 1 V, the differential amplifier must have a large common mode rejection. Various amplifying designs are shown, although the increased amplification decreases bandwidth. Bench tests show that the amplifier can withstand significant common mode DC voltage and measure 10 ns, and 50 mV signals.

  19. Noise in phase-preserving linear amplifiers

    NASA Astrophysics Data System (ADS)

    Pandey, Shashank; Jiang, Zhang; Combes, Joshua; Caves, Carlton M.

    2014-12-01

    The purpose of a phase-preserving linear amplifier is to make a small signal larger, so that it can be perceived by instruments incapable of resolving the original signal, while sacrificing as little as possible in signal-to-noise. Quantum mechanics limits how well this can be done: the noise added by the amplifier, referred to the input, must be at least half a quantum at the operating frequency. This well-known quantum limit only constrains the second moments of the added noise. Here we provide the quantum constraints on the entire distribution of added noise: any phasepreserving linear amplifier is equivalent to a parametric amplifier with a physical state σ for the ancillary mode; σ determines the properties of the added noise.

  20. Tester periodically registers dc amplifier characteristics

    NASA Technical Reports Server (NTRS)

    Cree, D.; Wenzel, G. E.

    1966-01-01

    Motor-driven switcher-recorder periodically registers the zero drift and gain drift signals of a dc amplifier subjected to changes in environment. A time coding method is used since several measurements are shared on a single recorder trace.

  1. Multi-pass light amplifier

    NASA Technical Reports Server (NTRS)

    Plaessmann, Henry (Inventor); Grossman, William M. (Inventor); Olson, Todd E. (Inventor)

    1996-01-01

    A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A resonator or a White Cell cavity is provided, including two or more mirrors (planar or curvilinearly shaped) facing each other along a resonator axis and an optical gain medium positioned on a resonator axis between the mirrors or adjacent to one of the mirrors. In a first embodiment, two curvilinear mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator. A second embodiment uses two curvilinear mirrors and one planar mirror, with a gain medium positioned in the optical path between each curvilinear mirror and the planar mirror. A third embodiment uses two curvilinear mirrors and two planar mirrors, with a gain medium positioned adjacent to a planar mirror. A fourth embodiment uses a curvilinear mirror and three planar mirrors, with a gain medium positioned adjacent to a planar mirror. A fourth embodiment uses four planar mirrors and a focusing lens system, with a gain medium positioned between the four mirrors. A fifth embodiment uses first and second planar mirrors, a focusing lens system and a third mirror that may be planar or curvilinear, with a gain medium positioned adjacent to the third mirror. A sixth embodiment uses two planar mirrors and a curvilinear mirror and a fourth mirror that may be planar or curvilinear, with a gain medium positioned adjacent to the fourth mirror. In a seventh embodiment, first and second mirrors face a third

  2. Energy transfer versus charge separation in hybrid systems of semiconductor quantum dots and Ru-dyes as potential co-sensitizers of TiO2-based solar cells

    NASA Astrophysics Data System (ADS)

    Giménez, Sixto; Rogach, Andrey L.; Lutich, Andrey A.; Gross, Dieter; Poeschl, Andreas; Susha, Andrei S.; Mora-Seró, Ivan; Lana-Villarreal, Teresa; Bisquert, Juan

    2011-07-01

    Hybrid structures of colloidal quantum dots (QDs) with Ru-dyes have been studied as candidates for panchromatic sensitizers for TiO2-based solar cells. Steady-state and time resolved photoluminescence spectroscopy and photocurrent measurements have been employed to identify the prevailing transfer mechanisms for photogenerated excitons between CdSe QDs capped with a traditional bulky organic ligand trioctylphosphine and Ru-dyes (N3 or Ru505) deposited onto inert glass or mesoporous TiO2 substrates. The type II energy level alignment between the QDs and both N3 and Ru505 offers a possibility for the directional charge separation, with electrons transferred to the QDs and holes to the dye. This scenario is indeed valid for the QD/Ru505 and TiO2/QD/Ru505 hybrid systems, with the negligible spectral overlap between the emission of the QDs and the absorption of the Ru505 dye. For the QD/N3 and TiO2/QD/N3 hybrid systems, the spectral overlap favors the longer range energy transfer from the QDs to N3, independently of the presence of the electron acceptor TiO2.

  3. MMIC Amplifiers for 90 to 130 GHz

    NASA Technical Reports Server (NTRS)

    Samoska, Lorene; Pukala, David; Peralta, Alejandro; Bryerton, Eric; Morgan, Matt; Boyd, T.; Hu, Ming; Schmitz, Adele

    2007-01-01

    This brief describes two monolithic microwave integrated-circuit (MMIC) amplifier chips optimized to function in the frequency range of 90 to 130 GHz, covering nearly all of F-band (90 - 140 GHz). These amplifiers were designed specifically for local-oscillator units in astronomical radio telescopes such as the Atacama Large Millimeter Array (ALMA). They could also be readily adapted for use in electronic test equipment, automotive radar systems, and communications systems that operate between 90 and 130 GHz.

  4. Direct solar-pumped iodine laser amplifier

    NASA Technical Reports Server (NTRS)

    Han, Kwang S.; Hwang, In Heon; Stock, Larry V.

    1989-01-01

    This semiannual progress report covers the period from September 1, 1988 to February 28, 1989 under NASA grant NAG-1-441 entitled, Direct Solar-Pumped Iodine Laser Amplifier. During this period, the research effort was concentrated on the solar pumped master oscillator power amplifier (MOPA) system using n-C3F7I. In the experimental work, the amplification measurement was conducted to identify the optimum conditions for amplification of the center's Vortek solar simulator pumped iodine laser amplifier. A modeling effort was also pursued to explain the experimental results in the theoretical work. The amplification measurement of the solar simulator pumped iodine laser amplifier is the first amplification experiment on the continuously pumped amplifier. The small signal amplification of 5 was achieved for the triple pass geometry of the 15 cm long solar simulator pumped amplifier at the n-C3F7I pressure of 20 torr, at the flow velocity of 6 m/sec and at the pumping intensity of 1500 solar constants. The XeCl laser pumped iodine laser oscillator, which was developed in the previous research, was employed as the master oscillator for the amplification measurement. In the theoretical work, the rate equations of the amplifier was established and the small signal amplification was calculated for the solar simulator pumped iodine laser amplifier. The amplification calculated from the kinetic equations with the previously measured rate coefficients reveals very large disagreement with experimental measurement. Moreover, the optimum condition predicted by the kinetic equation is quite discrepant with that measured by experiment. This fact indicates the necessity of study in the measurement of rate coefficients of the continuously pumped iodine laser system.

  5. High-Frequency, Conformable Organic Amplifiers.

    PubMed

    Reuveny, Amir; Lee, Sunghoon; Yokota, Tomoyuki; Fuketa, Hiroshi; Siket, Christian M; Lee, Sungwon; Sekitani, Tsuyoshi; Sakurai, Takayasu; Bauer, Siegfried; Someya, Takao

    2016-05-01

    Large-bandwidth, low-operation-voltage, and uniform organic amplifiers are fabricated on ultrathin foils. By the integration of short-channel OTFTs and AlOx capacitors, organic amplifiers with a bandwidth of 25 kHz are realized, demonstrating the highest gain-bandwidth product (GBWP) reported to date. Owing to material and process advancements, closed-loop architectures operate at frequencies of several kilohertz with an area smaller than 30 mm(2) . PMID:26922899

  6. Efficient Power Amplifier for Motor Control

    NASA Technical Reports Server (NTRS)

    Brown, R. J.

    1986-01-01

    Pulse-width-modulated amplifier supplies high current as efficiently as low current needed for starting and running motor. Key to efficiency of motor-control amplifier is V-channel metal-oxide/semiconductor transistor Q1. Device has low saturation resistance. However, has large gate input capacitance and small margin between its turn-on voltage and maximum allowable gate-to-source voltage. Circuits for output stages overcome limitations of VMOS device.

  7. Some Notes on Wideband Feedback Amplifiers

    DOE R&D Accomplishments Database

    Fitch, V.

    1949-03-16

    The extension of the passband of wideband amplifiers is a highly important problem to the designer of electronic circuits. Throughout the electronics industry and in many research programs in physics and allied fields where extensive use is made of video amplifiers, the foremost requirement is a passband of maximum width. This is necessary if it is desired to achieve a more faithful reproduction of transient wave forms, a better time resolution in physical measurements, or perhaps just a wider band gain-frequency response to sine wave signals. The art of electronics is continually faced with this omnipresent amplifier problem. In particular, the instrumentation techniques of nuclear physics require amplifiers with short rise times, a high degree of gain stability, and a linear response to high signal levels. While the distributed amplifier may solve the problems of those seeking only a wide passband, the requirements of stability and linearity necessitate using feedback circuits. This paper considers feedback amplifiers from the standpoint of high-frequency performance. The circuit conditions for optimum steady-state (sinusoidal) and transient response are derived and practical circuits (both interstage and output) are presented which fulfill these conditions. In general, the results obtained may be applied to the low-frequency end.

  8. Multiple excitation regenerative amplifier inertial confinement system

    DOEpatents

    George, Victor E. [Livermore, CA; Haas, Roger A. [Pleasanton, CA; Krupke, William F. [Pleasanton, CA; Schlitt, Leland G. [Livermore, CA

    1980-05-27

    The invention relates to apparatus and methods for producing high intensity laser radiation generation which is achieved through an optical amplifier-storage ring design. One or two synchronized, counterpropagating laser pulses are injected into a regenerative amplifier cavity and amplified by gain media which are pumped repetitively by electrical or optical means. The gain media excitation pulses are tailored to efficiently amplify the laser pulses during each transit. After the laser pulses have been amplified to the desired intensity level, they are either switched out of the cavity by some switch means, as for example an electro-optical device, for any well known laser end uses, or a target means may be injected into the regenerative amplifier cavity in such a way as to intercept simultaneously the counterpropagating laser pulses. One such well known end uses to which this invention is intended is for production of high density and temperature plasmas suitable for generating neutrons, ions and x-rays and for studying matter heated by high intensity laser radiation.

  9. Multiple excitation regenerative amplifier inertial confinement system

    DOEpatents

    George, V.E.; Haas, R.A.; Krupke, W.F.; Schlitt, L.G.

    1980-05-27

    The invention relates to apparatus and methods for producing high intensity laser radiation generation which is achieved through an optical amplifier-storage ring design. One or two synchronized, counterpropagating laser pulses are injected into a regenerative amplifier cavity and amplified by gain media which are pumped repetitively by electrical or optical means. The gain media excitation pulses are tailored to efficiently amplify the laser pulses during each transit. After the laser pulses have been amplified to the desired intensity level, they are either switched out of the cavity by some switch means, as for example an electro-optical device, for any well known laser end uses, or a target means may be injected into the regenerative amplifier cavity in such a way as to intercept simultaneously the counterpropagating laser pulses. One such well known end uses to which this invention is intended is for production of high density and temperature plasmas suitable for generating neutrons, ions and x-rays and for studying matter heated by high intensity laser radiation. 11 figs.

  10. V-band IMPATT power amplifier

    NASA Technical Reports Server (NTRS)

    Schell, S. W.

    1985-01-01

    This program is the result of the continuing demand and future requirement for a high data rate 60-GHz communications link. A reliable solid-state transmitter which delivers the necessary power over a wide bandwidth using the present IMPATT diode technology required the development of combining techniques. The development of a 60-GHz IMPATT power combiner amplifier is detailed. The results form a basis from which future wideband, high-power IMPATT amplifiers may be developed. As a result, several state-of-the-art advancements in millimeter-wave components technology were achieved. Specific achievements for the amplifier integration were: development of a nonresonant divider/combiner circuit; reproducible multiple junction circulator assemblies; and reliable high power 60-GHz IMPATT diodes. The various design approaches and tradeoffs which lead to the final amplifier configuration are discussed. A detailed circuit design is presented for the various amplifier components, and the conical line combiner, radial line combiner, and circulator development are discussed. The performance of the amplifier, the overall achievement of the program, the implications of the results, and an assessment of future development needs and recommendations are examined.

  11. V-band IMPATT power amplifier

    NASA Astrophysics Data System (ADS)

    Schell, S. W.

    1985-09-01

    This program is the result of the continuing demand and future requirement for a high data rate 60-GHz communications link. A reliable solid-state transmitter which delivers the necessary power over a wide bandwidth using the present IMPATT diode technology required the development of combining techniques. The development of a 60-GHz IMPATT power combiner amplifier is detailed. The results form a basis from which future wideband, high-power IMPATT amplifiers may be developed. As a result, several state-of-the-art advancements in millimeter-wave components technology were achieved. Specific achievements for the amplifier integration were: development of a nonresonant divider/combiner circuit; reproducible multiple junction circulator assemblies; and reliable high power 60-GHz IMPATT diodes. The various design approaches and tradeoffs which lead to the final amplifier configuration are discussed. A detailed circuit design is presented for the various amplifier components, and the conical line combiner, radial line combiner, and circulator development are discussed. The performance of the amplifier, the overall achievement of the program, the implications of the results, and an assessment of future development needs and recommendations are examined.

  12. Real Time Calibration Method for Signal Conditioning Amplifiers

    NASA Technical Reports Server (NTRS)

    Medelius, Pedro J. (Inventor); Mata, Carlos T. (Inventor); Eckhoff, Anthony (Inventor); Perotti, Jose (Inventor); Lucena, Angel (Inventor)

    2004-01-01

    A signal conditioning amplifier receives an input signal from an input such as a transducer. The signal is amplified and processed through an analog to digital converter and sent to a processor. The processor estimates the input signal provided by the transducer to the amplifier via a multiplexer. The estimated input signal is provided as a calibration voltage to the amplifier immediately following the receipt of the amplified input signal. The calibration voltage is amplified by the amplifier and provided to the processor as an amplified calibration voltage. The amplified calibration voltage is compared to the amplified input signal, and if a significant error exists, the gain and/or offset of the amplifier may be adjusted as necessary.

  13. Exponential Gain and Saturation of a Self-Amplified Spontaneous Emission Free-Electron Laser

    NASA Astrophysics Data System (ADS)

    Milton, S. V.; Gluskin, E.; Arnold, N. D.; Benson, C.; Berg, W.; Biedron, S. G.; Borland, M.; Chae, Y.-C.; Dejus, R. J.; Den Hartog, P. K.; Deriy, B.; Erdmann, M.; Eidelman, Y. I.; Hahne, M. W.; Huang, Z.; Kim, K.-J.; Lewellen, J. W.; Li, Y.; Lumpkin, A. H.; Makarov, O.; Moog, E. R.; Nassiri, A.; Sajaev, V.; Soliday, R.; Tieman, B. J.; Trakhtenberg, E. M.; Travish, G.; Vasserman, I. B.; Vinokurov, N. A.; Wang, X. J.; Wiemerslage, G.; Yang, B. X.

    2001-06-01

    Self-amplified spontaneous emission in a free-electron laser has been proposed for the generation of very high brightness coherent x-rays. This process involves passing a high-energy, high-charge, short-pulse, low-energy-spread, and low-emittance electron beam through the periodic magnetic field of a long series of high-quality undulator magnets. The radiation produced grows exponentially in intensity until it reaches a saturation point. We report on the demonstration of self-amplified spontaneous emission gain, exponential growth, and saturation at visible (530 nanometers) and ultraviolet (385 nanometers) wavelengths. Good agreement between theory and simulation indicates that scaling to much shorter wavelengths may be possible. These results confirm the physics behind the self-amplified spontaneous emission process and forward the development of an operational x-ray free-electron laser.

  14. Automatic alignment of double optical paths in excimer laser amplifier

    NASA Astrophysics Data System (ADS)

    Wang, Dahui; Zhao, Xueqing; Hua, Hengqi; Zhang, Yongsheng; Hu, Yun; Yi, Aiping; Zhao, Jun

    2013-05-01

    A kind of beam automatic alignment method used for double paths amplification in the electron pumped excimer laser system is demonstrated. In this way, the beams from the amplifiers can be transferred along the designated direction and accordingly irradiate on the target with high stabilization and accuracy. However, owing to nonexistence of natural alignment references in excimer laser amplifiers, two cross-hairs structure is used to align the beams. Here, one crosshair put into the input beam is regarded as the near-field reference while the other put into output beam is regarded as the far-field reference. The two cross-hairs are transmitted onto Charge Coupled Devices (CCD) by image-relaying structures separately. The errors between intersection points of two cross-talk images and centroid coordinates of actual beam are recorded automatically and sent to closed loop feedback control mechanism. Negative feedback keeps running until preset accuracy is reached. On the basis of above-mentioned design, the alignment optical path is built and the software is compiled, whereafter the experiment of double paths automatic alignment in electron pumped excimer laser amplifier is carried through. Meanwhile, the related influencing factors and the alignment precision are analyzed. Experimental results indicate that the alignment system can achieve the aiming direction of automatic aligning beams in short time. The analysis shows that the accuracy of alignment system is 0.63μrad and the beam maximum restoration error is 13.75μm. Furthermore, the bigger distance between the two cross-hairs, the higher precision of the system is. Therefore, the automatic alignment system has been used in angular multiplexing excimer Main Oscillation Power Amplification (MOPA) system and can satisfy the requirement of beam alignment precision on the whole.

  15. High-Efficiency Microwave Power Amplifier

    NASA Technical Reports Server (NTRS)

    Sims, Williams H.

    2005-01-01

    A high-efficiency power amplifier that operates in the S band (frequencies of the order of a few gigahertz) utilizes transistors operating under class-D bias and excitation conditions. Class-D operation has been utilized at lower frequencies, but, until now, has not been exploited in the S band. Nominally, in class D operation, a transistor is switched rapidly between "on" and "off" states so that at any given instant, it sustains either high current or high voltage, but not both at the same time. In the ideal case of zero "on" resistance, infinite "off" resistance, zero inductance and capacitance, and perfect switching, the output signal would be a perfect square wave. Relative to the traditional classes A, B, and C of amplifier operation, class D offers the potential to achieve greater power efficiency. In addition, relative to class-A amplifiers, class-D amplifiers are less likely to go into oscillation. In order to design this amplifier, it was necessary to derive mathematical models of microwave power transistors for incorporation into a larger mathematical model for computational simulation of the operation of a class-D microwave amplifier. The design incorporates state-of-the-art switching techniques applicable only in the microwave frequency range. Another major novel feature is a transmission-line power splitter/combiner designed with the help of phasing techniques to enable an approximation of a square-wave signal (which is inherently a wideband signal) to propagate through what would, if designed in a more traditional manner, behave as a more severely band-limited device (see figure). The amplifier includes an input, a driver, and a final stage. Each stage contains a pair of GaAs-based field-effect transistors biased in class D. The input signal can range from -10 to +10 dBm into a 50-ohm load. The table summarizes the performances of the three stages

  16. Development of a Broadband NbTiN Traveling Wave Parametric Amplifier for MKID Readout

    NASA Astrophysics Data System (ADS)

    Bockstiegel, C.; Gao, J.; Vissers, M. R.; Sandberg, M.; Chaudhuri, S.; Sanders, A.; Vale, L. R.; Irwin, K. D.; Pappas, D. P.

    2014-08-01

    The sensitivity of microwave kinetic inductance detectors (MKIDs) using dissipation readout is limited by the noise temperature of the cryogenic amplifier, usually a HEMT with 5 K. A lower noise amplifier is required to improve NEP and reach the photon noise limit at millimeter wavelengths. Eom et al. have proposed a kinetic inductance traveling wave (KIT) parametric amplifier (also called the dispersion-engineered travelling wave kinetic inductance parametric amplifier) that utilizes the nonlinearity with very low dissipation of NbTiN. This amplifier has the promise to achieve quantum limited noise, broad bandwidth, and high dynamic range, all of which are required for ideal MKID dissipation readout. We have designed a KIT amplifier which consists of a 2.2 m long coplanar waveguide transmission line fabricated in a double spiral format, with periodic loadings and impedance transformers at the input/output ports on a 2 by 2 cm Si chip. The design was fabricated with 20 nm NbTiN films. The device has shown over 10 dB of gain from 4 to 11 GHz. We have found the maximum gain is limited by abrupt breakdown at defects in the transmission line in the devices. By cascading two devices, more than 20 dB of gain was achieved from 4.5 to 12.5 GHz, with a peak of 27 dB.

  17. Neratinib overcomes trastuzumab resistance in HER2 amplified breast cancer.

    PubMed

    Canonici, Alexandra; Gijsen, Merel; Mullooly, Maeve; Bennett, Ruth; Bouguern, Noujoude; Pedersen, Kasper; O'Brien, Neil A; Roxanis, Ioannis; Li, Ji-Liang; Bridge, Esther; Finn, Richard; Siamon, Dennis; McGowan, Patricia; Duffy, Michael J; O'Donovan, Norma; Crown, John; Kong, Anthony

    2013-10-01

    Trastuzumab has been shown to improve the survival outcomes of HER2 positive breast cancer patients. However, a significant proportion of HER2-positive patients are either inherently resistant or develop resistance to trastuzumab. We assessed the effects of neratinib, an irreversible panHER inhibitor, in a panel of 36 breast cancer cell lines. We further assessed its effects with or without trastuzumab in several sensitive and resistant breast cancer cells as well as a BT474 xenograft model. We confirmed that neratinib was significantly more active in HER2-amplified than HER2 non-amplified cell lines. Neratinib decreased the activation of the 4 HER receptors and inhibited downstream pathways. However, HER3 and Akt were reactivated at 24 hours, which was prevented by the combination of trastuzumab and neratinib. Neratinib also decreased pHER2 and pHER3 in acquired trastuzumab resistant cells. Neratinib in combination with trastuzumab had a greater growth inhibitory effect than either drug alone in 4 HER2 positive cell lines. Furthermore, trastuzumab in combination with neratinib was growth inhibitory in SKBR3 and BT474 cells which had acquired resistance to trastuzumab as well as in a BT474 xenograft model. Innately trastuzumab resistant cell lines showed sensitivity to neratinib, but the combination did not enhance response compared to neratinib alone. Levels of HER2 and phospho-HER2 showed a direct correlation with sensitivity to neratinib. Our data indicate that neratinib is an effective anti-HER2 therapy and counteracted both innate and acquired trastuzumab resistance in HER2 positive breast cancer. Our results suggest that combined treatment with trastuzumab and neratinib is likely to be more effective than either treatment alone for both trastuzumab-sensitive breast cancer as well as HER2-positive tumors with acquired resistance to trastuzumab. PMID:24009064

  18. Neratinib overcomes trastuzumab resistance in HER2 amplified breast cancer

    PubMed Central

    Mullooly, Maeve; Bennett, Ruth; Bouguern, Noujoude; Pedersen, Kasper; O'Brien, Neil A; Roxanis, Ioannis; Li, Ji-Liang; Bridge, Esther; Finn, Richard; Slamon, Dennis; McGowan, Patricia; Duffy, Michael J.

    2013-01-01

    Trastuzumab has been shown to improve the survival outcomes of HER2 positive breast cancer patients. However, a significant proportion of HER2-positive patients are either inherently resistant or develop resistance to trastuzumab. We assessed the effects of neratinib, an irreversible panHER inhibitor, in a panel of 36 breast cancer cell lines. We further assessed its effects with or without trastuzumab in several sensitive and resistant breast cancer cells as well as a BT474 xenograft model. We confirmed that neratinib was significantly more active in HER2-amplified than HER2 non-amplified cell lines. Neratinib decreased the activation of the 4 HER receptors and inhibited downstream pathways. However, HER3 and Akt were reactivated at 24 hours, which was prevented by the combination of trastuzumab and neratinib. Neratinib also decreased pHER2 and pHER3 in acquired trastuzumab resistant cells. Neratinib in combination with trastuzumab had a greater growth inhibitory effect than either drug alone in 4 HER2 positive cell lines. Furthermore, trastuzumab in combination with neratinib was growth inhibitory in SKBR3 and BT474 cells which had acquired resistance to trastuzumab as well as in a BT474 xenograft model. Innately trastuzumab resistant cell lines showed sensitivity to neratinib, but the combination did not enhance response compared to neratinib alone. Levels of HER2 and phospho-HER2 showed a direct correlation with sensitivity to neratinib. Our data indicate that neratinib is an effective anti-HER2 therapy and counteracted both innate and acquired trastuzumab resistance in HER2 positive breast cancer. Our results suggest that combined treatment with trastuzumab and neratinib is likely to be more effective than either treatment alone for both trastuzumab-sensitive breast cancer as well as HER2-positive tumors with acquired resistance to trastuzumab. PMID:24009064

  19. Capillary Array Waveguide Amplified Fluorescence Detector for mHealth

    PubMed Central

    Balsam, Joshua; Bruck, Hugh Alan; Rasooly, Avraham

    2013-01-01

    Mobile Health (mHealth) analytical technologies are potentially useful for carrying out modern medical diagnostics in resource-poor settings. Effective mHealth devices for underserved populations need to be simple, low cost, and portable. Although cell phone cameras have been used for biodetection, their sensitivity is a limiting factor because currently it is too low to be effective for many mHealth applications, which depend on detection of weak fluorescent signals. To improve the sensitivity of portable phones, a capillary tube array was developed to amplify fluorescence signals using their waveguide properties. An array configured with 36 capillary tubes was demonstrated to have a ~100X increase in sensitivity, lowering the limit of detection (LOD) of mobile phones from 1000 nM to 10 nM for fluorescein. To confirm that the amplification was due to waveguide behavior, we coated the external surfaces of the capillaries with silver. The silver coating interfered with the waveguide behavior and diminished the fluorescence signal, thereby proving that the waveguide behavior was the main mechanism for enhancing optical sensitivity. The optical configuration described here is novel in several ways. First, the use of capillaries waveguide properties to improve detection of weak florescence signal is new. Second we describe here a three dimensional illumination system, while conventional angular laser waveguide illumination is spot (or line), which is functionally one-dimensional illumination, can illuminate only a single capillary or a single column (when a line generator is used) of capillaries and thus inherently limits the multiplexing capability of detection. The planar illumination demonstrated in this work enables illumination of a two dimensional capillary array (e.g. x columns and y rows of capillaries). In addition, the waveguide light propagation via the capillary wall provides a third dimension for illumination along the axis of the capillaries. Such an

  20. Critical-Dimension Controllability of Chemically Amplified Resists for X-Ray Membrane Mask Fabrication

    NASA Astrophysics Data System (ADS)

    Ezaki, Mizunori; Nakayama, Yoshinori; Kikuchi, Yukiko; Tsuboi, Shinji; Watanabe, Hiroshi; Aoyama, Hajime; Matsui, Yasuji; Morosawa, Tetsuo; Ohki, Shigehisa; Saito, Kenichi; Matsuda, Tadahito

    2000-12-01

    The key issues in highly precise X-ray mask fabrication are the high-performance electron beam writer and the mask process on a thin membrane. By the combination of 100 kV electron beam system EB-X3 and highly sensitive chemically amplified resist, the high resolution and the excellent critical-dimension (CD) uniformity of 50-100 nm line-and-space and isolated-space features were obtained with no proximity correction. Temperature uniformity of various hot plate bakers during the post-exposure bake process and CD controllability of pattern size with chemically amplified resists were studied and the 3σ variation of pattern size written in a membrane using chemically amplified resists was reduced to less than 10 nm with an optimized hot plate baker. As a result, the e-beam sensitivity and writing time for 4G-bit level ULSI patterns of chemically amplified resist were reduced to less than half of those with conventional ZEP-520 resist, while the resolution capability and CD accuracy of the membrane mask with chemically amplified resist UV6-SL were almost equal to those with ZEP-520.

  1. Improved Grid-Array Millimeter-Wave Amplifier

    NASA Technical Reports Server (NTRS)

    Rosenberg, James J.; Rutledge, David B.; Smith, R. Peter; Weikle, Robert

    1993-01-01

    Improved grid-array amplifiers operating at millimeter and submillimeter wavelengths developed for use in communications and radar. Feedback suppressed by making input polarizations orthogonal to output polarizations. Amplifier made to oscillate by introducing some feedback. Several grid-array amplifiers concatenated to form high-gain beam-amplifying unit.

  2. Method to amplify variable sequences without imposing primer sequences

    DOEpatents

    Bradbury, Andrew M.; Zeytun, Ahmet

    2006-11-14

    The present invention provides methods of amplifying target sequences without including regions flanking the target sequence in the amplified product or imposing amplification primer sequences on the amplified product. Also provided are methods of preparing a library from such amplified target sequences.

  3. Injection- Seeded Optoplasmonic Amplifier in the Visible

    PubMed Central

    Gartia, Manas Ranjan; Seo, Sujin; Kim, Junhwan; Chang, Te-Wei; Bahl, Gaurav; Lu, Meng; Liu, Gang Logan; Eden, J. Gary

    2014-01-01

    A hybrid optoplasmonic amplifier, injection-seeded by an internally-generated Raman signal and operating in the visible (563–675 nm), is proposed and evidence for amplification is presented. Comprising a gain medium tethered to a whispering gallery mode (WGM) resonator with a protein, and a plasmonic surface, the optical system described here selectively amplifies a single (or a few) Raman line(s) produced within the WGM resonator and is well-suited for routing narrowband optical power on-a-chip. Over the past five decades, optical oscillators and amplifiers have typically been based on the buildup of the field from the spontaneous emission background. Doing so limits the temporal coherence of the output, lengthens the time required for the optical field intensity to reach saturation, and often is responsible for complex, multiline spectra. In addition to the spectral control afforded by injection-locking, the effective Q of the amplifier can be specified by the bandwidth of the injected Raman signal. This characteristic contrasts with previous WGM-based lasers and amplifiers for which the Q is determined solely by the WGM resonator. PMID:25156810

  4. Thermal recovery of the NIF amplifiers

    NASA Astrophysics Data System (ADS)

    Sutton, Steven B.; Erlandson, A. E.; London, Richard A.; Manes, Kenneth R.; Marshall, Christopher D.; Petty, Charles S.; Pierce, R.; Smith, Larry K.; Zapata, Luis E.; Beullier, J.; Bicrel, B.

    1999-07-01

    With approximately 99 percent of the electrical energy supplied to the NIF appearing as heat in the amplifiers, thermal recovery of the NIF system is a major consideration in the design process. The NIF shot rate is one shot every 8 hours, with a goal of 4 hours between shots. This necessitates that thermal recovery take place in no more than 7 hours, with a goal of 3 hours for the accelerated shot rate. Residual optical distortions, which restrict the shot rate, are grouped into two discrete categories: (1) distortions associated with residual temperature gradients in the laser slabs, and (2) distortions associated with buoyantly driven convective currents in the amplifier cavity and beam-tube regions. Thermal recovery of the amplifiers is achieved by cooling the flashlamps and blastshields with a heat deposited in the slabs and edge claddings. Advanced concepts, such as the use of slightly chilled gas to accelerate some aspects of recovery, are addressed. To quantify recovery rates of the amplifiers, experiments and numerical models are used to measure and calculate the temperatures and optical distortions in NIF-like amplifier elements. The calculation results are benchmarked against AMPLAB temperature measurements, thus allowing a quantitative prediction of NIF thermal recovery. These results indicate that the NIF requirement of 7 hour thermal recovery can be achieved with chilled temperature cooling gas. It is further shown that residual temperature gradient driven distortions in the slabs reach an acceptable level, after 4 hours of thermal recovery.

  5. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, Lloyd A.; Dane, Clifford B.

    1993-01-01

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  6. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, L.A.; Dane, C.B.

    1993-08-24

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  7. Operational amplifier with adjustable frequency response.

    PubMed

    Gulisek, D; Hencek, M

    1978-01-01

    The authors describe an operational amplifier with an adjustable frequency response and its use in membrane physiology, using the voltage clamp and current clamp method. The amplifier eliminates feedback poles causing oscillation. It consists of a follower with a high input resistance in the form of a tube and of an actual amplifier with an adjustable frequency response allowing the abolition of clicks by one pole and of oscillation by two poles in the 500 Hz divided by infinity range. Further properties of the amplifier: a long-term voltage drift of 1 mv, a temperature voltage drift of 0.5 mv/degrees K, input resistance greater than 1 GOhm, amplification greater than 80 dB, output +/- 12 v, 25 ma, noise, measured from the width of the oscilloscope track in the presence of a ray of normal brightness, not exceeding 50 muv in the 0-250 kHz band, f1 = 1 MHz. A short report on the amplifier was published a few years ago (Gulísek and Hencek 1973). PMID:149322

  8. Alkaline Phosphatase Tagged Antibodies on Gold Nanoparticles/TiO2 Nanotubes Electrode: A Plasmonic Strategy for Label-Free and Amplified Photoelectrochemical Immunoassay.

    PubMed

    Zhu, Yuan-Cheng; Zhang, Nan; Ruan, Yi-Fan; Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-06-01

    This work reports a plasmonic strategy capable of label-free yet amplified photoelectrochemical (PEC) immunoassay for the sensitive and specific detection of model protein p53, an important transcription factor that regulates the cell cycle and functions as a tumor suppressor. Specifically, on the basis of Au nanoparticles (NPs) deposited on hierarchically ordered TiO2 nanotubes (NTs), a protein G molecular membrane was used for immobilization of alkaline phosphatase (ALP) conjugated anti-p53 (ALP-a-p53). Due to the immunological recognition between the receptor and target, the plasmonic charge separation from Au NPs to the conduction band of TiO2 NTs could be influenced greatly that originated from multiple factors. The degree of signal suppression is directly associated with the target concentration, so by monitoring the changes of the plasmonic photocurrent responding after the specific binding, a new plasmonic PEC immunoassay could be tailored for label-free and amplified detection. The operating principle of this study could be extended as a general protocol for numerous other targets of interest. PMID:27150939

  9. READOUT ASIC FOR 3D POSITION-SENSITIVE DETECTORS.

    SciTech Connect

    DE GERONIMO,G.; VERNON, E.; ACKLEY, K.; DRAGONE, A.; FRIED, J.; OCONNOR, P.; HE, Z.; HERMAN, C.; ZHANG, F.

    2007-10-27

    We describe an application specific integrated circuit (ASIC) for 3D position-sensitive detectors. It was optimized for pixelated CZT sensors, and it measures, corresponding to an ionizing event, the energy and timing of signals from 121 anodes and one cathode. Each channel provides low-noise charge amplification, high-order shaping, along with peak- and timing-detection. The cathode's timing can be measured in three different ways: the first is based on multiple thresholds on the charge amplifier's voltage output; the second uses the threshold crossing of a fast-shaped signal; and the third measures the peak amplitude and timing from a bipolar shaper. With its power of 2 mW per channel the ASIC measures, on a CZT sensor Connected and biased, charges up to 100 fC with an electronic resolution better than 200 e{sup -} rms. Our preliminary spectral measurements applying a simple cathode/mode ratio correction demonstrated a single-pixel resolution of 4.8 keV (0.72 %) at 662 keV, with the electronics and leakage current contributing in total with 2.1 keV.

  10. Design of an Auto-zeroed, Differential, Organic Thin-film Field-effect Transistor Amplifier for Sensor Applications

    NASA Technical Reports Server (NTRS)

    Binkley, David M.; Verma, Nikhil; Crawford, Robert L.; Brandon, Erik; Jackson, Thomas N.

    2004-01-01

    Organic strain gauge and other sensors require high-gain, precision dc amplification to process their low-level output signals. Ideally, amplifiers would be fabricated using organic thin-film field-effect transistors (OTFT's) adjacent to the sensors. However, OTFT amplifiers exhibit low gain and high input-referred dc offsets that must be effectively managed. This paper presents a four-stage, cascaded differential OTFT amplifier utilizing switched capacitor auto-zeroing. Each stage provides a nominal voltage gain of four through a differential pair driving low-impedance active loads, which provide common-mode output voltage control. p-type pentacence OTFT's are used for the amplifier devices and auto-zero switches. Simulations indicate the amplifier provides a nominal voltage gain of 280 V/V and effectively amplifies a 1-mV dc signal in the presence of 500-mV amplifier input-referred dc offset voltages. Future work could include the addition of digital gain calibration and offset correction of residual offsets associated with charge injection imbalance in the differential circuits.

  11. A Low-Voltage Chopper-Stabilized Amplifier for Fetal ECG Monitoring With a 1.41 Power Efficiency Factor.

    PubMed

    Song, Shuang; Rooijakkers, Michael; Harpe, Pieter; Rabotti, Chiara; Mischi, Massimo; van Roermund, Arthur H M; Cantatore, Eugenio

    2015-04-01

    This paper presents a low-voltage current-reuse chopper-stabilized frontend amplifier for fetal ECG monitoring. The proposed amplifier allows for individual tuning of the noise in each measurement channel, minimizing the total power consumption while satisfying all application requirements. The low-voltage current reuse topology exploits power optimization in both the current and the voltage domain, exploiting multiple supply voltages (0.3, 0.6 and 1.2 V). The power management circuitry providing the different supplies is optimized for high efficiency (peak charge-pump efficiency = 90%).The low-voltage amplifier together with its power management circuitry is implemented in a standard 0.18 μm CMOS process and characterized experimentally. The amplifier core achieves both good noise efficiency factor (NEF=1.74) and power efficiency factor (PEF=1.05). Experiments show that the amplifier core can provide a noise level of 0.34 μVrms in a 0.7 to 182 Hz band, consuming 1.17 μW power. The amplifier together with its power management circuitry consumes 1.56 μW, achieving a PEF of 1.41. The amplifier is also validated with adult ECG and pre-recorded fetal ECG measurements. PMID:25879971

  12. AIDA: A 16-channel amplifier ASIC to read out the advanced implantation detector array for experiments in nuclear decay spectroscopy

    SciTech Connect

    Braga, D.; Coleman-Smith, P. J.; Davinson, T.; Lazarus, I. H.; Page, R. D.; Thomas, S.

    2011-07-01

    We have designed a read-out ASIC for nuclear decay spectroscopy as part of the AIDA project - the Advanced Implantation Detector Array. AIDA will be installed in experiments at the Facility for Antiproton and Ion Research in GSI, Darmstadt. The AIDA ASIC will measure the signals when unstable nuclei are implanted into the detector, followed by the much smaller signals when the nuclei subsequently decay. Implant energies can be as high as 20 GeV; decay products need to be measured down to 25 keV within just a few microseconds of the initial implants. The ASIC uses two amplifiers per detector channel, one covering the 20 GeV dynamic range, the other selectable over a 20 MeV or 1 GeV range. The amplifiers are linked together by bypass transistors which are normally switched off. The arrival of a large signal causes saturation of the low-energy amplifier and a fluctuation of the input voltage, which activates the link to the high-energy amplifier. The bypass transistors switch on and the input charge is integrated by the high-energy amplifier. The signal is shaped and stored by a peak-hold, then read out on a multiplexed output. Control logic resets the amplifiers and bypass circuit, allowing the low-energy amplifier to measure the subsequent decay signal. We present simulations and test results, demonstrating the AIDA ASIC operation over a wide range of input signals. (authors)

  13. Single mode terahertz quantum cascade amplifier

    SciTech Connect

    Ren, Y. Wallis, R.; Shah, Y. D.; Jessop, D. S.; Degl'Innocenti, R.; Klimont, A.; Kamboj, V.; Beere, H. E.; Ritchie, D. A.

    2014-10-06

    A terahertz (THz) optical amplifier based on a 2.9 THz quantum cascade laser (QCL) structure has been demonstrated. By depositing an antireflective coating on the QCL facet, the laser mirror losses are enhanced to fully suppress the lasing action, creating a THz quantum cascade (QC) amplifier. Terahertz radiation amplification has been obtained, by coupling a separate multi-mode THz QCL of the same active region design to the QC amplifier. A bare cavity gain is achieved and shows excellent agreement with the lasing spectrum from the original QCL without the antireflective coating. Furthermore, a maximum optical gain of ∼30 dB with single-mode radiation output is demonstrated.

  14. Ultrashort pulse amplification in cryogenically cooled amplifiers

    DOEpatents

    Backus, Sterling J.; Kapteyn, Henry C.; Murnane, Margaret Mary

    2004-10-12

    A laser amplifier system amplifies pulses in a single "stage" from .about.10.sup.-9 joules to more than 10.sup.-3 joules, with average power of 1-10 watts, and beam quality M.sup.2 <2. The laser medium is cooled substantially below room temperature, as a means to improve the optical and thermal characteristics of the medium. This is done with the medium inside a sealed, evacuated or purged cell to avoid moisture or other materials condensing on the surface. A "seed" pulse from a separate laser is passed through the laser medium, one or more times, in any of a variety of configurations including single-pass, multiple-pass, and regenerative amplifier configurations.

  15. Optical switches based on semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Kalman, Robert F.; Dias, Antonio R.; Chau, Kelvin K.; Goodman, Joseph W.

    1991-12-01

    Fiber-optic switching systems typically exhibit large losses associated with splitting and combining of the optical power, and with excess component losses. These losses increase quickly with switch size. To obtain acceptable signal-to-noise performance through large optical switching, optical amplifiers can be used. In applications requiring optical switching, semiconductor optical amplifiers (SOAs) are preferred over erbium-doped fiber amplifiers due to their fast switching speeds and the possibility of their integration in monolithic structures with passive waveguides and electronics. We present a general analysis of optical switching systems utilizing SOAs. These systems, in which the gain provided by SOAs is distributed throughout the optical system, are referred to as distributed optical gain (DOG) systems. Our model predicts the performance and achievable sizes of switches based on the matrix-vector multiplier crossbar and Benes network. It is found that for realistic SOA parameters optical switches accommodating extremely large numbers of nodes are, in principle, achievable.

  16. High Bandwidth Differential Amplifier for Shock Experiments

    SciTech Connect

    Ross, P. W., Tran, V., Chau, R.

    2012-04-30

    We developed a high bandwidth differential amplifier for gas gun shock experiments/applications. The circuit has a bandwidth > 1 GHz, and is capable of measuring signals of ≤1.5 V with a common mode rejection of 250 V. Conductivity measurements of gas gun targets are measured by flowing high currents through the targets. The voltage is measured across the target using a technique similar to a four-point probe. Because of the design of the current source and load, the target voltage is approximately 250 V relative to ground. Since the expected voltage change in the target is < 1 V, the differential amplifier must have a large common mode rejection. High pass filters suppress internal ringing of operational amplifiers. Results of bench tests are shown.

  17. Short pulse free electron laser amplifier

    DOEpatents

    Schlitt, Leland G.; Szoke, Abraham

    1985-01-01

    Method and apparatus for amplification of a laser pulse in a free electron laser amplifier where the laser pulse duration may be a small fraction of the electron beam pulse duration used for amplification. An electron beam pulse is passed through a first wiggler magnet and a short laser pulse to be amplified is passed through the same wiggler so that only the energy of the last fraction, f, (f<1) of the electron beam pulse is consumed in amplifying the laser pulse. After suitable delay of the electron beam, the process is repeated in a second wiggler magnet, a third, . . . , where substantially the same fraction f of the remainder of the electron beam pulse is consumed in amplification of the given short laser pulse in each wiggler magnet region until the useful electron beam energy is substantially completely consumed by amplification of the laser pulse.

  18. Transverse intensity transformation by laser amplifiers

    NASA Astrophysics Data System (ADS)

    Litvin, Igor A.; King, Gary; Collett, Oliver J. P.; Strauss, Hencharl J.

    2015-03-01

    Lasers beams with a specific intensity profile such as super-Gaussian, Airy or Dougnut-like are desirable in many applications such as laser materials processing, medicine and communications. We propose a new technique for laser beam shaping by amplifying a beam in an end-pumped bulk amplifier that is pumped with a beam that has a modified intensity profile. Advantages of this method are that it is relatively easy to implement, has the ability to reshape multimode beams and is naturally suited to high power/energy beams. Both three and four level gain materials can be used as amplifier media. However, a big advantage of using three level materials is their ability to attenuate of the seed beam, which enhances the contrast of the shaping. We first developed a numerical method to obtain the required pump intensity for an arbitrary beam transformation. This method was subsequently experimentally verified using a three level system. The output of a 2.07 μm seed laser was amplified in a Ho:YLF bulk amplifier which was being pumped by a 1.89 μm Tm:YLF laser which had roughly a TEM10 Hermit Gaussian intensity profile. The seed beam was amplified from 0.3 W to 0.55 W at the full pump power of 35 W. More importantly, the beam profile in one transverse direction was significantly shaped from Gaussian to roughly flat-top, as the model predicted. The concept has therefore been shown to be viable and can be used to optimise the beam profile for a wide range of applications.

  19. Beyond nonlinear saturation of backward Raman amplifiers

    DOE PAGESBeta

    Barth, Ido; Toroker, Zeev; Balakin, Alexey A.; Fisch, Nathaniel J.

    2016-06-27

    Backward Raman amplification is limited by relativistic nonlinear dephasing resulting in saturation of the leading spike of the amplified pulse. We employed pump detuning in order to mitigate the relativistic phase mismatch and to overcome the associated saturation. In an amplified pulse can then be reshaped into a monospike pulse with little precursory power ahead of it, with the maximum intensity increasing by a factor of two. Finally, this detuning can be employed advantageously both in regimes where the group velocity dispersion is unimportant and where the dispersion is important but small.

  20. Beyond nonlinear saturation of backward Raman amplifiers.

    PubMed

    Barth, Ido; Toroker, Zeev; Balakin, Alexey A; Fisch, Nathaniel J

    2016-06-01

    Backward Raman amplification is limited by relativistic nonlinear dephasing resulting in saturation of the leading spike of the amplified pulse. Pump detuning is employed to mitigate the relativistic phase mismatch and to overcome the associated saturation. The amplified pulse can then be reshaped into a monospike pulse with little precursory power ahead of it, with the maximum intensity increasing by a factor of two. This detuning can be employed advantageously both in regimes where the group velocity dispersion is unimportant and where the dispersion is important but small. PMID:27415380