Sample records for charge sensitive amplifier

  1. Low-power Charge Sensitive Amplifier for Semiconductor Scintillator

    E-print Network

    Stanacevic, Milutin

    was implemented in 0.5µm CMOS process with a 5 V power supply. I. INTRODUCTION There is a great needLow-power Charge Sensitive Amplifier for Semiconductor Scintillator Xiao Yun, Milutin Stana) for measurement of optical response of photo-detector reg- istering light produced by semiconductor scintillator

  2. High sensitivity charge amplifier for ion beam uniformity monitor

    SciTech Connect

    Johnson, Gary W. (Livermore, CA)

    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.

  3. A Low Noise and High Dynamic Charge Sensitive Amplifier-Shaper associated with Silicon Strip

    E-print Network

    Paris-Sud XI, Université de

    A Low Noise and High Dynamic Charge Sensitive Amplifier-Shaper associated with Silicon Strip (Equivalent Noise Charge) of 412 electrons rms. 75% of the total noise is generated by the small value of the feedback resistor chosen to avoid pile up phenomenon due to the 1E5 hits/s occupancy rate. A cross

  4. A low-power low-noise CMOS charge-sensitive amplifier for capacitive detectors

    Microsoft Academic Search

    Mohammad Beikahmadi; Shahriar Mirabbasi

    2011-01-01

    In this paper, the design of a new low-power low- noise charge-sensitive amplifier (CSA) is presented. The proposed CSA is intended for capacitive sensor readout circuits such as interface circuits for solid-state detectors used in medical imaging and X-ray spectroscopy. A comprehensive noise analysis of read- out systems that consist of a CSA followed by an RC-CR pulse shaper is

  5. 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

  6. Charge amplifier with bias compensation

    SciTech Connect

    Johnson, Gary W. (Livermore, CA)

    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.

  7. Improvement of spectroscopic performance using a charge-sensitive amplifier circuit for an X-ray astronomical SOI pixel detector

    NASA Astrophysics Data System (ADS)

    Takeda, A.; Tsuru, T. G.; Tanaka, T.; Uchida, H.; Matsumura, H.; Arai, Y.; Mori, K.; Nishioka, Y.; Takenaka, R.; Kohmura, T.; Nakashima, S.; Kawahito, S.; Kagawa, K.; Yasutomi, K.; Kamehama, H.; Shrestha, S.

    2015-06-01

    We have been developing monolithic active pixel sensors series, named ``XRPIX'', based on the silicon-on-insulator (SOI) pixel technology, for future X-ray astronomical satellites. The XRPIX series offers high coincidence time resolution (~ 1 ?s), superior readout time (~ 10 ?s), and a wide energy range (0.5–40 keV) . In the previous study, we successfully demonstrated X-ray detection by event-driven readout of XRPIX2b. We here report recent improvements in spectroscopic performance. We successfully increased the gain and reduced the readout noise in XRPIX2b by decreasing the parasitic capacitance of the sense-node originated in the buried p-well (BPW) . On the other hand, we found significant tail structures in the spectral response due to the loss of the charge collection efficiency when a small BPW is employed. Thus, we increased the gain in XRPIX3b by introducing in-pixel charge sensitive amplifiers instead of having even smaller BPW . We finally achieved the readout noise of 35 e? (rms) and the energy resolution of 320 eV (FWHM) at 6 keV without significant loss of the charge collection efficiency.

  8. High sensitivity amplifier/discriminator for PWC's

    SciTech Connect

    Hansen, S.

    1983-01-01

    The facility support group at Fermilab is designing and building a general purpose beam chamber for use in several locations at the laboratory. This pwc has 128 wires per plane spaced 1 mm apart. An initial production of 25 signal planes is anticipated. In proportional chambers, the size of the signal depends exponentially on the charge stored per unit of length along the anode wire. As the wire spacing decreases, the capacitance per unit length decreases, thereby requiring increased applied voltage to restore the necessary charge per unit length. In practical terms, this phenomenon is responsible for difficulties in constructing chambers with less than 2 mm wire spacing. 1 mm chambers, therefore, are frequently operated very near to their breakdown point and/or a high gain gas containing organic compounds such as magic gas is used. This argon/iso-butane mixture has three drawbacks: it is explosive when exposed to the air, it leaves a residue on the wires after extended use and is costly. An amplifier with higher sensitivity would reduce the problems associated with operating chambers with small wire spacings and allow them to be run a safe margin below their breakdown voltage even with an inorganic gas mixture such as argon/CO2, this eliminating the need to use magic gas. Described here is a low cost amplifier with a usable threshold of less than 0.5 ..mu..A. Data on the performance of this amplifier/discriminator in operation on a prototype beam chamber are given. This data shows the advantages of the high sensitivity of this design.

  9. Noise beating in hybrid phase-sensitive amplifier systems.

    PubMed

    Corcoran, B; Malik, R; Olsson, S L I; Lundström, C; Karlsson, M; Andrekson, P A

    2014-03-10

    We investigate the effect of noise loading in a hybrid phase-sensitive amplifier system, analyzing the effect of noise beating between the signal and idler waves coupled in a parametric amplifier. Through analyzing input and output optical signal to noise ratios, we find that system performance of a phase-sensitive amplifier is 3 to 6 dB improved over a phase-insensitive amplifier, depending on the ratio of loaded noise power to that of vacuum fluctuations. PMID:24663914

  10. Simulations of Charge Gain and Collection Efficiency from Diamond Amplifiers

    SciTech Connect

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

    2010-03-15

    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, we have been developing models, within the VORPAL computational framework, to simulate secondary electron generation and charge transport in diamond. The implemented models include inelastic scattering of electrons and holes for generation of electron-hole pairs, elastic, phonon, and charge impurity scattering. We will discuss these models and present results from 3D VORPAL simulations on charge gain and collection efficiency as a function of primary electron energy and applied electric field. The implemented modeling capabilities already allow us to investigate specific effects and compare simulation results with experimental data.

  11. A grounded-load charge amplifier for reducing hysteresis in piezoelectric tube scanners

    Microsoft Academic Search

    A. J. Fleming; S. O. R. Moheimani

    2005-01-01

    In this paper, a charge amplifier adapted for piezoelectric tube scanners is presented. Previous problems involved with the implementation of such amplifiers are resolved to provide dc accurate performance with zero voltage drift. In our experiment, hysteresis was reduced by 89% when compared to a voltage amplifier.

  12. Privacy-Sensitive Congestion Charging

    Microsoft Academic Search

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

    2006-01-01

    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 chal- lenge 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

  13. Privacy-Sensitive Congestion Charging

    Microsoft Academic Search

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

    2009-01-01

    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

  14. A grounded-load charge amplifier for reducing hysteresis in piezoelectric tube scanners

    E-print Network

    Fleming, Andrew J.

    A grounded-load charge amplifier for reducing hysteresis in piezoelectric tube scanners A. J 2005 In this paper, a charge amplifier adapted for piezoelectric tube scanners is presented. Previous Piezoelectric tube scanners were reported by Binnig and Smith1 for use in scanning tunneling microscopes.2

  15. An InSb charge amplifier for use in a spectrometer array

    Microsoft Academic Search

    Don Hartill; Franco Lisi; Andrea Bettarini

    1986-01-01

    An eight-channel, low-noise charge amplifier system developed for an InSb photodiode array is described. The InSb charge amplifier is composed of: eight FET-input integrating preamplifiers inside the cold Dewar, a set of correlated double samples, and a sequence controller. The functions of the components are discussed and block and circuit diagrams of the system are presented. The amplifier's rest switch

  16. 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?

  17. 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.

  18. How to interpret Methylation Sensitive Amplified Polymorphism (MSAP) profiles?

    PubMed Central

    2014-01-01

    Background DNA methylation plays a key role in development, contributes to genome stability, and may also respond to external factors supporting adaptation and evolution. To connect different types of stimuli with particular biological processes, identifying genome regions with altered 5-methylcytosine distribution at a genome-wide scale is important. Many researchers are using the simple, reliable, and relatively inexpensive Methylation Sensitive Amplified Polymorphism (MSAP) method that is particularly useful in studies of epigenetic variation. However, electrophoretic patterns produced by the method are rather difficult to interpret, particularly when MspI and HpaII isoschizomers are used because these enzymes are methylation-sensitive, and any C within the CCGG recognition motif can be methylated in plant DNA. Results Here, we evaluate MSAP patterns with respect to current knowledge of the enzyme activities and the level and distribution of 5-methylcytosine in plant and vertebrate genomes. We discuss potential caveats related to complex MSAP patterns and provide clues regarding how to interpret them. We further show that addition of combined HpaII?+?MspI digestion would assist in the interpretation of the most controversial MSAP pattern represented by the signal in the HpaII but not in the MspI profile. Conclusions We recommend modification of the MSAP protocol that definitely discerns between putative hemimethylated mCCGG and internal CmCGG sites. We believe that our view and the simple improvement will assist in correct MSAP data interpretation. PMID:24393618

  19. Modeling of Yb3+-sensitized Er3+-doped silica waveguide amplifiers

    Microsoft Academic Search

    Christian Lester; Anders Bjarklev; Thomas Rasmussen; Palle Geltzer Dinesen

    1995-01-01

    A model for Yb3+-sensitized Er3+-doped silica waveguide amplifiers is described and numerically investigated in the small-signal regime. The amplified spontaneous emission in the ytterbium-band and the quenching process between excited erbium ions are included in the model. For pump wavelengths between 860 and 995 nm, the amplified spontaneous emission in the ytterbium-band is found to reduce both the gain and

  20. A charge-transfer amplifier and an encoded-bus architecture for low-power SRAM's

    Microsoft Academic Search

    Shoichiro Kawashima; Toshihiko Mori; Ryuhei Sasagawa; Makoto Hamaminato; Shigetoshi Wakayama; Kazuo Sukegawa; Isao Fukushi

    1998-01-01

    This paper proposes and reports a low-power SRAM using a charge-transfer (CT) pre-sense amplifier and a bus signal encoding scheme. The CT amplifier overcomes the Vth relative difference between the pair MOS transistors, and thus reduces the input offset voltage. The encoded-bus scheme reduces the number of signals being switched to cut the capacitive load. These read-path dynamic circuits have

  1. Position Sensitive Detection System for Charged Particles

    SciTech Connect

    Coello, E. A. [Instituto de Fisica, Univ. Nacional Autonoma de Mexico; Favela, F. [Instituto de Fisica, Univ. Nacional Autonoma de Mexico; Curiel, Q. [Instituto de Fisica, Univ. Nacional Autonoma de Mexico; Chavez, E [Instituto de Fisica, Univ. Nacional Autonoma de Mexico; Huerta, A. [Instituto de Fisica, Univ. Nacional Autonoma de Mexico; Varela, A. [Instituto Nacional de Investigaciones Nucleares, Ocoyoacac, Mexico; Shapira, Dan [ORNL

    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.

  2. Wide-Band Low-Noise Charge Sensitive Preamplifier

    Microsoft Academic Search

    T. V. Blalock

    1966-01-01

    This paper presents the design considerations and experimental characteristics of a transistorized charge-sensitive preamplifier that has a noise line-width significantly lower than that of the best vacuum-tube preamplifiers, and a high gain-bandwidth product which allows stabilization of the charge gain against detector capacitance fluctuations over a wide range of pulse-shaping time-constants. The open-loop gain of both the input charge-sensitive section

  3. 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.

  4. 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

  5. Influence of momentum and charge conservation on azimuthally sensitive correlations

    E-print Network

    Zuzana Fecková; Boris Tomášik

    2012-12-13

    Charge neutralisation procedure based on a Markov chain Monte Carlo algorithm is applied to a system of generated hadrons. The algorithm changes the charge of a randomly picked particle by shifting it within its isomultiplet. For baryons changes in both electric charge and baryon number are applied and the algorithm leads to charge and baryon number neutralisation. The procedure can thus be used to study the effects of the local charge and baryon number conservation. We attempt to study these together with the local momentum conservation and their effect on azimuthal correlator observable sensitive to local C and CP violation in quark-gluon plasma.

  6. Theory and modeling of a relativistic klystron amplifier with high space charge for microsecond applications

    SciTech Connect

    Carlsten, B.E.; Fazio, M.V.; Faehl, R.J.; Kwan, T.J.; Rickel, D.G.; Stringfield, R.M.

    1992-01-01

    We discuss basic Relativistic Klystron Amplifier physics. We show that in the intense space-charge regime the maximum power extraction does not coincide with the maximum harmonic bunching. In addition, we show that as the beam is bunched, the additional power stored in the Coulomb fields does not add significantly to the overall power extraction. Because of these effects, the power extraction at 1.3 GHz for a 500 kV, 5 kA beam with reasonable beam-to-wall spacing is limited to around 35%. 3 refs., 17 figs.

  7. Calibration of bridge-, charge- and voltage amplifiers for dynamic measurement applications

    NASA Astrophysics Data System (ADS)

    Klaus, Leonard; Bruns, Thomas; Volkers, Henrik

    2015-02-01

    Measuring amplifiers are used for transducer output signal conditioning in many dynamic measurement applications. For a traceable measurement, a calibration of all components of the measuring chain—and therefore of the conditioning amplifiers, too—is mandatory. In this paper methods for a dynamic calibration of different types of conditioning amplifiers are presented. Measurement uncertainties and calibration results for typical amplifiers are discussed.

  8. 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.

  9. 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 ?m ridge width, and a cavity length of 900 ?m. 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.

  10. A novel charge sensitive preamplifier without the feedback resistor

    Microsoft Academic Search

    Giuseppe Bertuccio; Pavel Rehak; Deming Xi

    1993-01-01

    A novel charge sensitive preamplifier#1#1 U.S. patent pending. which has no resistor in parallel with the feedback capacitor is presented. No external device or circuit is required to discharge the feedback capacitor. The detector leakage and signal current flows away through the gate of the input JFET which works with its gate to source junction slightly forward biased. The DC

  11. Cortical-striatal gene expression in neonatal hippocampal lesion (NVHL)-amplified cocaine sensitization.

    PubMed

    Chambers, R A; McClintick, J N; Sentir, A M; Berg, S A; Runyan, M; Choi, K H; Edenberg, H J

    2013-07-01

    Cortical-striatal circuit dysfunction in mental illness may enhance addiction vulnerability. Neonatal ventral hippocampal lesions (NVHL) model this dual diagnosis causality by producing a schizophrenia syndrome with enhanced responsiveness to addictive drugs. Rat genome-wide microarrays containing >24?000 probesets were used to examine separate and co-occurring effects of NVHLs and cocaine sensitization (15?mg/kg/day?×?5?days) on gene expression within medial prefrontal cortex (MPFC), nucleus accumbens (NAC), and caudate-putamen (CAPU). Two weeks after NVHLs robustly amplified cocaine behavioral sensitization, brains were harvested for genes of interest defined as those altered at P?sensitization, including 11 downregulated by NVHL in MPFC/NAC, and 10 upregulated by NVHL or cocaine in CAPU. These findings suggest that structural and functional impoverishment of prefrontal-cortical-accumbens circuits in mental illness is associated with abnormal striatal plasticity compounding with that in addictive disease. Polygenetic interactions impacting neuronal signaling and morphology within these networks likely contribute to addiction vulnerability in mental illness. PMID:23682998

  12. PRC2 loss amplifies Ras-driven transcription and confers sensitivity to BRD4-based therapies.

    PubMed

    De Raedt, Thomas; Beert, Eline; Pasmant, Eric; Luscan, Armelle; Brems, Hilde; Ortonne, Nicolas; Helin, Kristian; Hornick, Jason L; Mautner, Victor; Kehrer-Sawatzki, Hildegard; Clapp, Wade; Bradner, James; Vidaud, Michel; Upadhyaya, Meena; Legius, Eric; Cichowski, Karen

    2014-10-01

    The polycomb repressive complex 2 (PRC2) exerts oncogenic effects in many tumour types. However, loss-of-function mutations in PRC2 components occur in a subset of haematopoietic malignancies, suggesting that this complex plays a dichotomous and poorly understood role in cancer. Here we provide genomic, cellular, and mouse modelling data demonstrating that the polycomb group gene SUZ12 functions as tumour suppressor in PNS tumours, high-grade gliomas and melanomas by cooperating with mutations in NF1. NF1 encodes a Ras GTPase-activating protein (RasGAP) and its loss drives cancer by activating Ras. We show that SUZ12 loss potentiates the effects of NF1 mutations by amplifying Ras-driven transcription through effects on chromatin. Importantly, however, SUZ12 inactivation also triggers an epigenetic switch that sensitizes these cancers to bromodomain inhibitors. Collectively, these studies not only reveal an unexpected connection between the PRC2 complex, NF1 and Ras, but also identify a promising epigenetic-based therapeutic strategy that may be exploited for a variety of cancers. PMID:25119042

  13. Sensitive profiling of biogenic amines in human urine by capillary electrophoresis with field amplified sample injection.

    PubMed

    Bacaloni, A; Insogna, S; Sancini, A; Ciarrocca, M; Sinibaldi, F

    2013-08-01

    In order to monitor biogenic amines in human urine, a method based on field-amplified sample injection combined with capillary electrophoresis and direct UV absorption detection was developed. Dopamine, tyramine, tryptamine, serotonin and epinephrine were effectively separated and identified in human urine samples, and detection limits were 0.072, 0.010, 0.027, 0.010 and 0.120 µmol/L, respectively. Detection limits comparable to laser-induced fluorescence detection or solid phase extraction combined with capillary electrophoresis were achieved. Parameters affecting electrophoretic system detection sensitivity were investigated. Optimal separation conditions were obtained using as background electrolyte a pH 6.5 mixture of 2-(morpholino)ethanesulfonic acid 20 mmol/L and 30 mmol/L phosphate buffer, containing 0.05% hydroxypropylcellulose and 10% v/v methanol. Injections of the sample solution were performed by applying a voltage of 12 kV for 50 s. Recovery and accuracy ranged between 89.4 and 94.9%, and 89 and 112%, respectively. The method was successfully applied on actual urine samples (from a healthy volunteer): target bioamine content was consistent with endogenous levels reported in the literature. The proposed method is simple, fast and inexpensive and can be conveniently employed in work-related stress studies. The affordability and noninvasive sampling of the method allow epidemiological studies on large number of exposed persons to be performed. PMID:23529872

  14. A low noise small area self switched CMOS charge sensitive readout chain

    SciTech Connect

    Kapnistis, C.; Misiakos, K.; Haralabidis, N. [N.C.S.R. Demokritos, Athens (Greece). Inst. of Microelectronics] [N.C.S.R. Demokritos, Athens (Greece). Inst. of Microelectronics

    1999-06-01

    A CMOS charge sensitive readout chain with self switched output and small layout area, suitable for pixel applications, has been developed. The system is capable of simultaneous position sensing and energy measurement on a real time basis. Each pixel circuit incorporates both analog and digital features to perform the dual task. The performance of several charge amplifiers was tested. The impact of type and channel length of the input transistor on the system noise was investigated. The read out electronics have been designed and fabricated in CMOS 0.8 {micro}m technology. The overall gain of the chain is 620 mV/fC, while the ENC is 58 e{sup {minus}} rms at a 140 nsec shaping time and a 105 fF detector capacitance. With a power consumption of 1.8 mW per pixel at 3.3V, it is a promising solution for X-ray pixel detectors. The paper describes the system architecture and reports experimental measurements.

  15. A high-performance cryogenic amplifier based on a radio-frequency single electron transistor

    E-print Network

    Segall, Ken

    amplifier based on a radio-frequency single-electron- transistor rf-SET . The high charge sensitivity impedance sources. In this letter we present a demonstration of a high- performance amplifier based on a rfA high-performance cryogenic amplifier based on a radio-frequency single electron transistor K

  16. Surface charge sensitivity of silicon nanowires: size dependence.

    PubMed

    Elfström, Niklas; Juhasz, Robert; Sychugov, Ilya; Engfeldt, Torun; Karlström, Amelie Eriksson; Linnros, Jan

    2007-09-01

    Silicon nanowires of different widths were fabricated in silicon on insulator (SOI) material using conventional process technology combined with electron-beam lithography. The aim was to analyze the size dependence of the sensitivity of such nanowires for biomolecule detection and for other sensor applications. Results from electrical characterization of the nanowires show a threshold voltage increasing with decreasing width. When immersed in an acidic buffer solution, smaller nanowires exhibit large conductance changes while larger wires remain unaffected. This behavior is also reflected in detected threshold shifts between buffer solutions of different pH, and we find that nanowires of width >150 nm are virtually insensitive to the buffer pH. The increased sensitivity for smaller sizes is ascribed to the larger surface/volume ratio for smaller wires exposing the channel to a more effective control by the local environment, similar to a surrounded gate transistor structure. Computer simulations confirm this behavior and show that sensing can be extended even down to the single charge level. PMID:17691849

  17. Charge transport in dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Yanagida, Masatoshi

    2015-03-01

    The effect of charge transport on the photovoltaic properties of dye-sensitized solar cells (DSCs) was investigated by the experimental results and the ion transport. The short current photocurrent density (Jsc) is determined by the electron transport in porous TiO2 when the diffusion limited current (Jdif) due to the {{I}3}- transport is larger than the photo-generated electron flux (Jg) estimated from the light harvesting efficiency of dye-sensitized porous TiO2 and the solar spectrum. However, the Jsc value is determined by the ion transport in the electrolyte solution at Jdif < Jg. The J value becomes constant against light intensity, and is expressed as the saturated current (Jscs). The {{J}s} value depends on the thickness (d) of the TiO2 layer, the initial concentration (COX0), and the diffusion coefficient (DOXb) of {{I}3}-. These suitable parameters were determined by using the ion transport. Invited talk at the 7th International Workshop on Advanced Materials Science and Nanotechnology IWAMSN2014, 2-6 November, 2014, Ha Long, Vietnam.

  18. Modeling and measurement of the noise figure of a cascaded non-degenerate phase-sensitive parametric amplifier.

    PubMed

    Tong, Zhi; Bogris, Adonis; Lundström, Carl; McKinstrie, C J; Vasilyev, Michael; Karlsson, Magnus; Andrekson, Peter A

    2010-07-01

    Semi-classical noise characteristics are derived for the cascade of a non-degenerate phase-insensitive (PI) and a phase-sensitive (PS) fiber optical parametric amplifier (FOPA). The analysis is proved to be consistent with the quantum theory under the large-photon number assumption. Based on this, we show that the noise figure (NF) of the PS-FOPA at the second stage can be obtained via relative-intensity-noise (RIN) subtraction method after averaging the signal and idler NFs. Negative signal and idler NFs are measured, and <2 dB NF at >16 dB PS gain is estimated when considering the combined signal and idler input, which is believed to be the lowest measured NF of a non-degenerate PS amplifier to this date. The limitation of the RIN subtraction method attributed to pump transferred noise and Raman phonon induced noise is also discussed. PMID:20639969

  19. Low-Power Amplifier for Readout Interface of Semiconductor Scintillator

    E-print Network

    Stanacevic, Milutin

    by scintillating semiconductor wafer in event of ionizing radiation event. Presented optimization procedure of the amplifier implemented in 0.5 µm CMOS technology, verify gain of 71 mV/fC, with the linearity measured at 1- /pF. Index Terms--Radiation detection, scintillator, readout IC, charged sensitive amplifier, pulse

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

    PubMed

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

    2015-05-10

    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 correlates with aggressive neuroblastoma and chemotherapy-based treatment failure, co-treatment with cathepsin inhibitors might be a better avenue for disease management. PMID:25883214

  1. 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 correlates with aggressive neuroblastoma and chemotherapy-based treatment failure, co-treatment with cathepsin inhibitors might be a better avenue for disease management. PMID:25883214

  2. Determination of Charge Sensitivity of a Tunnel Diode Voltage Threshold Discriminator Used in Time Difference Measurements

    Microsoft Academic Search

    P. D. Compton; W. A. Johnson

    1967-01-01

    The results of an investigation of the delay time variation of a tunnel diode (TD) threshold sensing discriminator are presented. These variations are a function of the square root of the input signal risetime and are accountable in terms of a charge sensitivity of the tunnel diode. A distinction is made between the charge sensitivity due to continuously rising signals

  3. Voltage Sensitivity and Gating Charge in Shaker and Shab Family Potassium Channels

    Microsoft Academic Search

    Leon D. Islas; Fred J. Sigworth

    1999-01-01

    The members of the voltage-dependent potassium channel family subserve a variety of functions and are expected to have voltage sensors with different sensitivities. The Shaker channel of Drosophila , which underlies a transient potassium current, has a high voltage sensitivity that is conferred by a large gating charge movement, z 13 elementary charges. A Shaker subunit's primary voltage-sensing (S4) region

  4. Sensitivity and open-loop control of stochastic response in a noise amplifier flow: the backward-facing step

    E-print Network

    Boujo, Edouard

    2014-01-01

    The two-dimensional backward-facing step flow is a canonical example of noise amplifier flow: global linear stability analysis predicts that it is stable, but perturbations can undergo large amplification in space and time as a result of non-normal effects. This amplification potential is best captured by optimal transient growth analysis, optimal harmonic forcing, or the response to sustained noise. In view of reducing disturbance amplification in these globally stable open flows, a variational technique is proposed to evaluate the sensitivity of stochastic amplification to steady control. Existing sensitivity methods are extended in two ways to achieve a realistic representation of incoming noise: (i) perturbations are time-stochastic rather than time-harmonic, (ii) perturbations are localised at the inlet rather than distributed in space. This allows for the identification of regions where small-amplitude control is the most effective, without actually computing any controlled flows. In particular, passive...

  5. Faradaic impedance to analyze charge recombination in photoelectrode of dye-sensitized solar cell

    Microsoft Academic Search

    Masayuki Itagaki; Yuya Nakano; Isao Shitanda; Kunihiro Watanabe

    2011-01-01

    Charge transfer on the photoelectrode of dye sensitized solar cell (DSC) is composed of the various processes as follows: photoexcitation of electron in the dye; electron injection from the excited dye into the conduction band of oxide semiconductor; electron diffusion in the oxide semiconductor, reaction between oxidized dye and iodide ions (I?); and charge recombination. The charge recombination is one

  6. Charge Recycling Sense Amplifier Based Logic: Securing Low Power Security IC's against

    E-print Network

    `side channels', such as time delay and power consumption, as an extra source of information to find and the internal nodes to an intermediate voltage in the precharge phase. This technique achieves a reduction inverter, (2) de- sign rules for cascading charge recycling dynamic gates, (3) the energy-delay performance

  7. Design of low-noise output amplifiers for P-channel charge-coupled devices fabricated on high-resistivity silicon

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

    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 highresistivity, 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+ 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+ polysilicon gate that connects directly to the p+ sense node. Output structures with buried-contact areas as small as 2 ?m × 2 ?m 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- rms at 70 kpixels/sec.

  8. Charge-sensitive fluorescent nanosensors created from nanodiamonds.

    PubMed

    Petrakova, V; Rehor, I; Stursa, J; Ledvina, M; Nesladek, M; Cigler, P

    2015-08-01

    We show that fluorescent nanodiamonds (FNDs) are among the few types of nanosensors that enable direct optical reading of noncovalent molecular events. The unique sensing mechanism is based on switching between the negatively charged and neutral states of NV centers which is induced by the interaction of the FND surface with charged molecules. PMID:26138745

  9. Development of CdTe hybrid detector with CMOS charge integration amplifier

    Microsoft Academic Search

    K. Fujita; K. Matsue; M. Ichikawa; K. Yamamoto

    2011-01-01

    A pixelated CdTe detector module is being developed for use in X-ray imaging application. The CdTe is expected to allow higher energy detection capability because of the high atomic number. And also, high resolution imaging becomes possible with a direct conversion method in which an incident X-ray photon is directly converted to electric charges. This paper reports the first results

  10. Phase-and-amplitude regeneration of differential phase-shift keyed signals using a phase-sensitive amplifier

    NASA Astrophysics Data System (ADS)

    Croussore, Kevin; Kim, Inwoong; Kim, Cheolhwan; Han, Yan; Li, Guifang

    2006-03-01

    DPSK phase-and-amplitude regeneration with a NOLM-based phase-sensitive amplifier is demonstrated experimentally. For a highly degraded input signal, maximum differential phase errors were reduced from 82° to 41°, while the SNR was improved by more than 5-dB. Differential phase Q-factor improvement was better than 6-dB. The PSA was operated free of excess noise due to stimulated Brillouin scattering by using a binary phase modulated pulse train as the pump. The impact of pump fluctuations on regeneration performance is clarified. The regenerated signal was characterized by measurement of the constellation diagram by linear optical sampling, giving the first directly measured evidence of DPSK phase regeneration.

  11. Sensitivity of Carbon Nanotube Transistors to a Charged Dielectric Coating

    Microsoft Academic Search

    Gary Pennington; Matthew H. Ervin; Alma E. Wickenden

    2008-01-01

    This paper investigates the electronic properties of single-walled carbon nanotube field-effect transistors (SWCNT-FETs) in which the SWCNT element is coated with a charged dielectric. The presence of remote charge on the surface of the dielectric is considered to effect carrier transport in the nanotube as a result of both carrier-scattering and gate screening. Nanotube device characteristics are simulated using the

  12. Charge and current-sensitive preamplifiers for pulse shape discrimination techniques with silicon detectors

    E-print Network

    H. Hamrita; E. Rauly; Y. Blumenfeld; B. Borderie; M. Chabot; P. Edelbruck; L. Lavergne; Th. Legou; J. Le Bris; N. Le Neindre; A. Richard; M. F. Rivet; J. A. Scarpaci; J. Tillier

    2004-07-13

    New charge and current-sensitive preamplifiers coupled to silicon detectors and devoted to studies in nuclear structure and dynamics have been developed and tested. For the first time shapes of current pulses from light charged particles and carbon ions are presented. Capabilities for pulse shape discrimination techniques are demonstrated.

  13. Charge structure and lightning sensitivity in a simulated multicell thunderstorm

    E-print Network

    Mansell, Edward "Ted"

    for rebounding graupel-droplet collisions. Each noninductive graupel-ice parameterization is combined; Saunders et al., 1991; Saunders and Peck, 1998] have confirmed that rebounding collisions between small incorporated laboratory results for charging due to ice rebounding particle collisions [Takahashi, 1978]. His

  14. Click chemistry-mediated catalytic hairpin self-assembly for amplified and sensitive fluorescence detection of Cu(2+) in human serum.

    PubMed

    Li, Daxiu; Zhou, Wenjiao; Chai, Yaqin; Yuan, Ruo; Xiang, Yun

    2015-07-23

    Chemically reduced Cu(2+) triggers the ligation of alkynyl- and azido-modified DNA via click chemistry. Subsequently, the ligated DNA initiates cyclic assembly of two fluorescently quenched hairpin DNAs and generates significantly amplified fluorescence signals for highly sensitive detection of Cu(2+) in human serum samples. PMID:26160681

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

    SciTech Connect

    Fuerstenau, Stephen Douglas (3938 Park Pl., Montrose, CA 91020); Soli, George Arthur (4003 Wanna Vista Dr., Vancouver, WA 98661)

    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.

  16. 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

  17. Charge Transport Limitations in Self-Assembled TiO2 Photoanodes for Dye-Sensitized Solar Cells

    E-print Network

    Steiner, Ullrich

    Charge Transport Limitations in Self-Assembled TiO2 Photoanodes for Dye-Sensitized Solar Cells and Storage; Energy and Charge Transport The dye-sensitized solar cell (DSC) has attracted wide- spread-sensitized solar cells offer the possibility of high-power conversion efficiencies due to theoretically lower

  18. Charge Transport Properties in TiO2 Network with Different Particle Sizes for Dye Sensitized Solar Cells

    E-print Network

    Cao, Guozhong

    the large improvement in performance of dye sensitized solar cells (DSCs) achieved in 1991, mesoporousCharge Transport Properties in TiO2 Network with Different Particle Sizes for Dye Sensitized Solar sensitized solar cells, nanoparticle size, impedance, charge transport properties INTRODUCTION Since

  19. Radio-Frequency Single-Electron Transistor as Readout Device for Qubits: Charge Sensitivity and Backaction

    Microsoft Academic Search

    A. Aassime; G. Johansson; G. Wendin; R. J. Schoelkopf; P. Delsing

    2001-01-01

    We study the radio-frequency single-electron transistor (rf-SET) as a readout device for charge qubits. We measure the charge sensitivity of an rf-SET to be 6.3mue\\/Hz and evaluate the backaction of the rf-SET on a single Cooper-pair box. This allows us to compare the needed measurement time with the mixing time of the qubit imposed by the measurement. We find that

  20. Space-charge-dominated mass spectrometry ion sources: Modeling and sensitivity

    Microsoft Academic Search

    Mark Busman; Jan Sunner; Curtis R. Vogel

    1991-01-01

    The factors determining the sensitivity of space-charge-dominated (SCD) unipolar ion sources, such as electrospray (ESP) and\\u000a corona atmospheric pressure ionization (API) have been studied theoretically. The most important parameters are the ion density\\u000a and ion drift time in the vicinity of the sampling orifice. These are obtained by solving a system of differential equations,\\u000a “the space-charge problem.” For some simple

  1. Non-coalescence of oppositely charged droplets in pH-sensitive emulsions

    PubMed Central

    Liu, Tingting; Seiffert, Sebastian; Thiele, Julian; Abate, Adam R.; Weitz, David A.; Richtering, Walter

    2012-01-01

    Like charges stabilize emulsions, whereas opposite charges break emulsions. This is the fundamental principle for many industrial and practical processes. Using micrometer-sized pH-sensitive polymeric hydrogel particles as emulsion stabilizers, we prepare emulsions that consist of oppositely charged droplets, which do not coalesce. We observe noncoalescence of oppositely charged droplets in bulk emulsification as well as in microfluidic devices, where oppositely charged droplets are forced to collide within channel junctions. The results demonstrate that electrostatic interactions between droplets do not determine their stability and reveal the unique pH-dependent properties of emulsions stabilized by soft microgel particles. The noncoalescence can be switched to coalescence by neutralizing the microgels, and the emulsion can be broken on demand. This unusual feature of the microgel-stabilized emulsions offers fascinating opportunities for future applications of these systems. PMID:22203968

  2. High sensitivity sensor for continuous direct measurement of bipolar charged aerosols

    NASA Astrophysics Data System (ADS)

    Baxter, Karen; Jones, Chris; Fletcher-Wood, Guy

    2008-12-01

    The disruptive generation of aerosols is known to cause particles to carry electrostatic charges. Anthropogenic aerosol may have a standard deviation of charges when generated that is different to other sources or equilibrated aerosols. A simple, low cost 'Bipolar Charged Aerosol Sensor' (BCAS) has been developed to continuously measure charged aerosol in the ambient environment in real-time. Direct measurement of the current released from the charged aerosol particles when they deposit onto an electrode in a DC field is achieved using custom designed, sensitive electrometers. The mobility range of particles collected is defined by the DC field strength, air flow rate through the instrument and the electrode geometry. The mobility range of interest has been selected based on measurements made previously with a complex Laser Doppler Velocimetry (LDV) based instrument. The BCAS has been assessed in laboratory. The sensor design and initial measurement data will be discussed.

  3. An advanced model for determining charge recombination kinetic parameters in dye-sensitized solar cells

    Microsoft Academic Search

    Po-Tsung Hsiao; Hsi-Sheng Teng

    2010-01-01

    Charge recombination between dye-sensitized TiO2 electrodes and I3? in the electrolytes governs the performance of dye-sensitized solar cells. The present work features a theoretical model constructed to explore the discrepancy of the recombination kinetics in light and dark. This study yielded two modified equations describing recombination behaviors in light and dark. These two equations simulated the photocurrent–voltage characteristics of a

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

    Microsoft Academic Search

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

    2009-01-01

    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

  5. Studies of coupled charge transport in dye-sensitized solar cells using a numerical simulation tool

    Microsoft Academic Search

    Kristofer Fredin; Sven Rühle; Catelijne Grasso; Anders Hagfeldt

    2006-01-01

    In this paper, we present a simulation platform designed to study coupled charge transport in dye-sensitized solar cell (DSC) devices. The platform, SLICE, is used to study the influence of ions in the electrolyte on electron transport in the nanoporous medium. The simulations indicate that both cationic and anionic properties should be considered when modelling DSCs and similar systems. Additionally,

  6. Enhanced laboratory sensitivity to variation of the fine-structure constant using highly charged ions.

    PubMed

    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 ?. 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 ? sensitivities seen in atomic systems. PMID:20867622

  7. 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. [School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia)

    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.

  8. Gated charged-particle trap

    DOEpatents

    Benner, W. Henry (Danville, CA)

    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.

  9. 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

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

    NASA Astrophysics Data System (ADS)

    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

    2014-09-01

    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.

  11. Sensitive gas sensor embedded in a vertical polymer space-charge-limited transistor

    NASA Astrophysics Data System (ADS)

    Zan, Hsiao-Wen; Li, Chang-Hung; Yu, Chih-Kuan; Meng, Hsin-Fei

    2012-07-01

    We report a very sensitive gas sensor embedded in a vertical polymer space-charge-limited transistor. The oxidizing and reducing gases act as electron dedoping and electron doping agents on the transistor active layer to change the potential distribution in the vertical channel and hence to change the output current density. With a 30-ppb detection limit to ammonia, the sensor can be used for non-invasive breath monitor in point-of-care applications. The integration of a sensitive gas sensor and a low-operation-voltage transistor in one single device also facilitates the development of low-cost and low-power-consumption sensor array.

  12. 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.

  13. Charge sensitive and incentive compatible end-to-end window-based control for selfish users

    Microsoft Academic Search

    Youngmi Jin; George Kesidis

    2006-01-01

    This paper considers the problem of finding a tamper-resistant and charge-sensitive end-to-end window flow-control mechanism for greedy users. Using a mathematical model of resource distribution, we propose a distributed window flow-control mechanism leading to a flow-rate vector which achieves maximum total utility. Desirable features of the proposed window control algorithm and properties of the equilibrium points are explored. We also

  14. A Sensitive Dissolved Oxygen Sensor Based on a Charge-Transfer Complex Modified Electrode

    Microsoft Academic Search

    TU Yifeng

    2006-01-01

    A charge-transfer complex was modified on the graphite paste electrode for making a sensitive dissolved oxygen sensor. It was composed of copper with two ligands of phenanthroline and 1,2-dicyano-1,2-dithiol- ethane. Because of the low redox potential of the core ion and the pull and repulsive effect from the ligands, the redox of modified complex toke place under lower potential and

  15. Polyanions Decelerate the Kinetics of Positively Charged Gramicidin Channels as Shown by Sensitized Photoinactivation

    Microsoft Academic Search

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

    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

  16. Polylysine decelerates kinetics of negatively charged gramicidin channels as shown by sensitized photoinactivation

    Microsoft Academic Search

    Andrey V Krylov; Yuri N Antonenko; Elena A Kotova; Tatiana I Rokitskaya; Alexander A Yaroslavov

    1998-01-01

    Effect of a cationic polymer, poly(l-lysine), on the kinetic properties of ionic channels formed by neutral gramicidin A (gA) and its negatively charged analogue O-pyromellitylgramicidin (OPg) in a bilayer lipid membrane is studied using a method of sensitized photoinactivation. This newly developed method is based on the analysis of transmembrane current transients induced by a flash in the presence of

  17. Sensitive analysis of amino acids and vitamin B3 in functional drinks via field-amplified stacking with reversed-field stacking in microchip electrophoresis.

    PubMed

    Wu, Minglei; Gao, Fan; Zhang, Yi; Wang, Qingjiang; Li, Hui

    2015-01-01

    An on-line preconcentration strategy combining field-amplified stacking and reversed-field stacking was developed for efficient and sensitive analysis of amino acids and vitamin B3 including lysine (Lys), taurine (Tau), and niacinamide (NA) by microchip electrophoresis with LIF detection. In this technique, the addition of a reversed-polarity step termed reversed-field stacking could enhance the preconcentration effect of field-amplified stacking and push most of the sample matrix out of the separation channel, thus greatly improving the sensitivity enhancement by 1-2 orders of magnitude over the classical MCE-LIF methods. The related mechanism as well as important parameters governing preconcentration and separation have been investigated in order to obtain strongest sensitivity amplification and maximum resolution. Under optimal conditions, all analytes were successfully focused and completely separated within 4 min. The limits of detection for Lys, Tau, and NA were 0.25, 0.50, and 0.20 nM (S/N=3), respectively, and enhancement factors of 165-, 285-, and 236-fold were obtained for Lys, Tau, and NA as compared to using the no concentration step. Other validation parameters such as linearity and precision were considered as satisfactory. The proposed method also gave accurate and reliable results in the analysis of these functional ingredients in eight functional drink samples. PMID:25281150

  18. Relationship between Resolution, Line Edge Roughness, and Sensitivity in Chemically Amplified Resist of Post-Optical Lithography Revealed by Monte Carlo and Dissolution Simulations

    NASA Astrophysics Data System (ADS)

    Saeki, Akinori; Kozawa, Takahiro; Tagawa, Seiichi

    2009-07-01

    The simultaneous achievement of high resolution and low line width (edge) roughness (LWR, LER) at acceptable sensitivity (RLS) in chemically-amplified resist (CAR) is in strong demand to realize the mass production of ultra-small electric circuit using extreme ultraviolet. We performed Monte Carlo and dissolution simulations of positive-tone CAR of electron beam lithography to clarify this RLS formation. The trade-off RLS relationship was successfully reproduced and discussed in terms of non-scaling law of exposed line width. It was demonstrated that LER follows the inverse of square root of exposure dose at moderate acid diffusion length.

  19. Success of the PCR-based replication assay depends on the number of methylation sensitive restriction sites in the PCR amplifying region.

    PubMed

    Metta, M K; Tantravahi, S; Kunaparaju, R

    2015-01-01

    The PCR—based replication assay is one of the most simple, quick and economical methods for the analysis of episomal replication. However, in spite of its advantages the method has not been able to replace the southern—based replication assay, the latter of which is a tedious and time—consuming process. This is due to the generation of spurious amplification products in the PCR—based replication assay. The replication assay is based on the use of methylation—sensitive restriction endonucleases (eg. DpnI, MboI) to distinguish bacterial replicated (adenosine methylated) and mammalian replicated plasmids (adenosine non—methylated). In this work we addressed the problem by evaluating (a) restriction enzyme digestion and (b) the minimum number of restriction sites that are required in the amplifying region. The efficiency of restriction digestion was tested by subjecting the plasmid to one and two rounds of digestion. Multiple rounds of digestions were found to be inefficient in preventing false positives when the number of DpnI sites in the amplifying region is less than 8. However, use of a minimum of 15 DpnI sites in the amplifying region was found to overcome the false positives. PMID:26068910

  20. Evaluation of different micro/nanobeads used as amplifiers in QCM immunosensor for more sensitive detection of E. coli O157:H7.

    PubMed

    Jiang, Xuesong; Wang, Ronghui; Wang, Yun; Su, Xiaoli; Ying, Yibin; Wang, Jianping; Li, Yanbin

    2011-11-15

    Micro/nanobeads with different materials (magnetic, silica and polymer) and different sizes (diameters from 30nm to 970nm) were investigated for their use as amplifiers in a quartz crystal microbalance (QCM) immunosensor for more sensitive detection of Escherichia coli O157:H7. The micro/nanobeads were conjugated with anti-E. coli antibodies. E. coli O157:H7 cells were first captured by the first antibody immobilized on the electrode surface, and then micro/nanobeads labeled secondary antibodies attached to the cells, and finally the complexes of antibody-E. coli-antibody modified beads were formed. The results showed that antibody-labeled beads lead to signal amplification in both the change in frequency (?F) and the change in resistance (?R). Since the penetration depth of the oscillation-induced shear-waves for a ?8MHz crystal is limited to 200nm, the interpretation of how the signal is amplified by the adsorbed particles was represented in terms of the coupled-oscillator theory. The amplification is not sensed in terms of increase in mass on the sensor surface. Amplification is sensed as a change in bacterial resonance frequency when the spheres adsorb to the bacteria. The change in the values of ?F caused by different micro/nanobeads (amplifiers) attaching on target bacterial cells is indicative of the ratio between the resonance frequency of the absorbed bacterial-particle complex (?(s)), and the resonance frequency of the crystal (?). PMID:21862307

  1. Dynamics of charge transport and recombination in ZnO nanorod array dye-sensitized solar cells

    E-print Network

    Dynamics of charge transport and recombination in ZnO nanorod array dye-sensitized solar cells Alex nanoparticles. Introduction Dye-Sensitized Solar Cells (DSSCs) comprise an increasingly attractive alternative photovoltaic technology.1,2 These photo- electrochemical cells use molecular dyes to sensitize high-area, wide

  2. A low-noise, wide-band CMOS charge-sensitive preamplifier for use with APD/LSO PET detectors

    SciTech Connect

    Paulus, M.J.; Andreaco, M.S.; Binkley, D.M. [CTI, Inc., Knoxville, TN (United States)] [CTI, Inc., Knoxville, TN (United States); Rochelle, J.M. [Univ. of Tennessee, Knoxville, TN (United States). Electrical and Computing Engineering Dept.] [Univ. of Tennessee, Knoxville, TN (United States). Electrical and Computing Engineering Dept.

    1996-06-01

    The recent emergence of LSO as a potential scintillator for positron emission tomography (PET) and recent improvements in avalanche photodiode (APD) technology offer encouragement that an APD/LSO based PET detector may be commercially viable in the near future. An important component of any APD/LSO based PET detector will be the preamplifier used to read out the low-level detector signals. Due to the large number of detectors (>18,000) in a high-resolution PET scanner, the preamplifier must be implemented as a monolithic integrated circuit. Additionally, in order to achieve the timing resolution required for high resolution PET, the preamplifier must have a large band-width and a low equivalent input noise voltage. This paper presents a CMOS charge-sensitive preamplifier design which uses local feedback to improve the performance of the common gate transistor. The modified cascode circuit is analyzed and compared with a previously reported simple folded cascode circuit. A prototype circuit was fabricated in a 2 {micro}m NWELL CMOS process. The prototype amplifier has a measured 10--90% rise-time of 7 ns with an external input capacitance of {approximately}6 pF and has an equivalent input noise voltage of {approximately}1.1 nV/rt-Hz above the flicker noise corner. A pulse height resolution of 14.3% FWHM and a timing resolution of 1.57 ns FWHM (vs. plastic) were obtained with the preamplifier, an Advanced Photonix 5 mm diameter beveled-edge APD and a 3.5 x 3.5 x 22 mm{sup 3} Teflon wrapped LSO crystal.

  3. Critique of charge collection efficiencies calculated through small perturbation measurements of dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Sivaram, Varun; Kirkpatrick, James; Snaith, Henry

    2013-02-01

    Through experiment and simulation, we critically examine the conventional method of extracting the charge collection efficiency, ?c, of dye-sensitized solar cells (DSSCs). We demonstrate that the collection efficiency extracted by measuring transient decay rates at short circuit deviates considerably from the true value as ?c decreases. This discrepancy arises from two sources of error: first, transient voltage decay rates are especially sensitive to perturbation size near short circuit, and second, the decay rates are influenced by transient equilibration between trapped and free charge during the measurement. Only if the collection efficiency is high (>90%) do the true and measured values coincide well. This finding finally elucidates the disparity between steady-state and transient measurements of the collection efficiency; the former is more accurate for devices with a low ?c, and the latter for devices with a high ?c. For the first time, we present a fully nondimensional model of the DSSC, allowing us to fit device parameters without extensive material knowledge. The resulting simulations and fitting of solid-state dye sensitized solar cells additionally enable us to quantify the inaccuracy of small perturbation measurements of the collection efficiency when ?c is below 90%.

  4. 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. (X-Ray Science Division); (Southern Federal Univ.); (Lund Univ.); (Northwestern Univ.)

    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.

  5. 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

  6. 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

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

    PubMed

    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

  8. Depth-charge static and time-dependence perturbation/sensitivity system for nuclear reactor core analysis. [LMFBR

    SciTech Connect

    White, J.R.

    1981-09-01

    This report provides the background theory, user input, and sample problems required for the efficient application of the DEPTH-CHARGE system - a code block for both static and time-dependence 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 Labortary. The DEPTH-CHARGE system provides, for the first time, a complete generalized first-order perturbation/sensitivity theory capability for both static and time-dependent analysis of realistic multidimensional reactor models.

  9. Evaluation of sensitivity for positive tone non-chemically and chemically amplified resists using ionized radiation: EUV, x-ray, electron and ion induced reactions

    NASA Astrophysics Data System (ADS)

    Oshima, Akihiro; Oyama, Tomoko Gowa; Washio, Masakazu; Tagawa, Seiichi

    2013-03-01

    The different exposure sources induce a different energy deposition in resist materials. Linear energy transfer (LET) effect for resist sensitivity is very important issue from the viewpoint of radiation induced chemical reactions for high-volume nanofabrication. The sensitivities of positive tone non-chemically (non-CA, ZEP) and chemically amplified (CA, UV-3) resist materials are evaluated using various ionized radiation such as EUV, soft X-rays, EB and various ion beams. Since the notations of sensitivity of resist vary with exposure sources, in order to evaluate systematically, the resist sensitivity were estimated in terms of absorbed dose in resist materials. Highly-monochromated EUV and soft X-rays (6.7 nm - 3.1 nm) from the BL27SU of the SPring-8, high energy ion beams (C6+, Ne10+, Mg12+, Si14+ , Ar18+, Kr36+ and Xe54+) with 6 MeV/u from MEXP of HIMAC, EB from low energy EB accelerator (Hamamatsu Photonics, EB-engine®, 100 kV) and EB lithography system (30 keV and 75keV) were used for the exposure. For non-CA and CA resist materials, it was found that LET effects for sensitivity would be hardly observed except for heavier ion beams. Especially, in the case of the high energy ion beam less than Si14+ with 6 MeV/u, it is suggested that the radiation induced chemical reaction would be equivalent to EUV, soft X-ray and EB exposure. Hence, it indicates that the resist sensitivity could be systematically evaluated by absorbed dose in resist materials.

  10. 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.

  11. An Amplifier Concept for Spintronics

    SciTech Connect

    Acremann, Y.; Yu, X.W.; Tulapurkar, A.A.; Scherz, A.; Chembrolu, V.; Katine, J.A.; Carey, M.J.; Siegmann, H.C.; Stohr, J.

    2009-05-11

    Typical spin-dependent devices proposed for information processing lack one of the most important features provided by charge based logic: they do not provide gain. In this letter we show the basic concept of a spin amplifier and propose ways to amplify a spin current at room temperature.

  12. 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.

  13. Design and noise analysis of charge sensitive amplifier for readout of pixelized thin film amorphous silicon sensors

    Microsoft Academic Search

    K. Poltorak; W. Dabrowski; P. Jarron; J. Kaplon

    2008-01-01

    Future high-energy physics experiments entail the need to improve the existing detection technologies, as well as develop new ones. Larger luminosities of the new accelerators require greater granularity of tracking detectors, which will be exposed to much higher doses of radiation. One of the newly-investigated solutions for tracking detectors is the Thin Film on ASIC (TFA) technology, which allows combining

  14. Overexpression of the Adiponectin Receptor AdipoR1 in Rat Skeletal Muscle Amplifies Local Insulin Sensitivity

    PubMed Central

    Patel, S. A.; Hoehn, K. L.; Lawrence, R. T.; Sawbridge, L.; Talbot, N. A.; Tomsig, J. L.; Turner, N.; Cooney, G. J.; Whitehead, J. P.; Kraegen, E. W.

    2012-01-01

    Adiponectin is an adipokine whose plasma levels are inversely related to degrees of insulin resistance (IR) or obesity. It enhances glucose disposal and mitochondrial substrate oxidation in skeletal muscle and its actions are mediated through binding to receptors, especially adiponectin receptor 1 (AdipoR1). However, the in vivo significance of adiponectin sensitivity and the molecular mechanisms of muscle insulin sensitization by adiponectin have not been fully established. We used in vivo electrotransfer to overexpress AdipoR1 in single muscles of rats, some of which were fed for 6 wk with chow or high-fat diet (HFD) and then subjected to hyperinsulinemic-euglycemic clamp. After 1 wk, the effects on glucose disposal, signaling, and sphingolipid metabolism were investigated in test vs. contralateral control muscles. AdipoR1 overexpression (OE) increased glucose uptake and glycogen accumulation in the basal and insulin-treated rat muscle and also in the HFD-fed rats, locally ameliorating muscle IR. These effects were associated with increased phosphorylation of insulin receptor substrate-1, Akt, and glycogen synthase kinase-3?. AdipoR1 OE also caused increased phosphorylation of p70S6 kinase, AMP-activated protein kinase, and acetyl-coA carboxylase as well as increased protein levels of adaptor protein containing pleckstrin homology domain, phosphotyrosine binding domain, and leucine zipper motif-1 and adiponectin, peroxisome proliferator activated receptor-? coactivator-1?, and uncoupling protein-3, indicative of increased mitochondrial biogenesis. Although neither HFD feeding nor AdipoR1 OE caused generalized changes in sphingolipids, AdipoR1 OE did reduce levels of sphingosine 1-phosphate, ceramide 18:1, ceramide 20:2, and dihydroceramide 20:0, plus mRNA levels of the ceramide synthetic enzymes serine palmitoyl transferase and sphingolipid ?-4 desaturase, changes that are associated with increased insulin sensitivity. These data demonstrate that enhancement of local adiponectin sensitivity is sufficient to improve skeletal muscle IR. PMID:22989629

  15. Extreme chemical sensitivity of nonlinear conductivity in charge-ordered LuFe2O4

    PubMed Central

    Cao, Shi; Li, Jun; Wang, Zhen; Tian, Huanfang; Qin, Yuanbin; Zeng, Lunjie; Ma, Chao; Yang, Huaixin; Li, Jianqi

    2012-01-01

    Nonlinear transport behaviors are crucial for applications in electronic technology. At the nonlinear critical turning point, the nonequilibrium states cause rich physics responses to environment. The corresponding study in this field is crucial for physics and industry application. Here nonlinear conductivity in charge-ordered (CO) LuFe2O4 has been demonstrated. Remarkable resistivity switching behavior was observed and the gas-sensing property can be reversibly tuned by a small alternation of partial pressure and/or chemical components of the environment. These facts allow us to use LuFe2O4 materials as a sensitive chemical gas sensor in technological applications. Careful analysis of the gas sensing process in LuFe2O4 suggests a novel sensing mechanism in sharp contrast with that discussed for the conventional gas sensors which depend fundamentally on surface chemical reactions. PMID:22448317

  16. 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.

  17. Amplified electrochemiluminescence of luminol based on hybridization chain reaction and in situ generate co-reactant for highly sensitive immunoassay.

    PubMed

    Xiao, Lijuan; Chai, Yaqin; Yuan, Ruo; Cao, Yaling; Wang, Haijun; Bai, Lijuan

    2013-10-15

    In this work, we described a simple and highly sensitive electrochemiluminescence (ECL) strategy for IgG detection. Firstly, L-cysteine functionalized reduced graphene oxide composite (L-cys-rGO) was decorated on the glassy carbon electrode (GCE) surface. Then anti-IgG was immobilized on the modified electrode surface through the interaction between the carboxylic groups of the L-cys-rGO and the amine groups in anti-IgG. And then biotinylated anti-IgG (bio-anti-IgG) was assembled onto the electrode surface based on the sandwich-type immunoreactions. By the conjunction of biotin and streptavidin (SA), SA was immobilized, which in turn, combined with the biotin labeled initiator strand (S1). In the presence of two single DNA strands of glucose oxidase labeled S2 (GOD-S2) and complementary strand (S3), S1 could trigger the hybridization chain reaction (HCR) among S1, GOD-S2 and S3. Herein, due to HCR, numerous GOD was efficiently immobilizated on the sensing surface and exhibited excellent catalysis towards glucose to in situ generate amounts of hydrogen peroxide (H2O2), which acted as luminol's co-reactant to significantly enhance the ECL signal. The proposed ECL immunosensor presented predominate stability and high sensibility for determination of IgG in the range from 0.1 pg mL(-1) to 100 ng mL(-1) with a detection limit of 33 fg mL(-1) (S/N=3). Additionally, the designed ECL immunosensor exhibited a promising application for other protein detection. PMID:24054635

  18. Calculation of rate constants for asymmetric charge transfer, and their effect on relative sensitivity factors in glow discharge mass spectrometry

    Microsoft Academic Search

    Annemie Bogaerts; Krassimir A. Temelkov; Nikolay K. Vuchkov; Renaat Gijbels

    2007-01-01

    For this paper, we have calculated the rate coefficients for asymmetric charge transfer between Ar+ ions and all elements of interest in analytical glow discharges, based on a semi-classical approach. These values were then used to make predictions on the relative sensitivity factors (RSFs) in glow discharge mass spectrometry (GDMS) (VG9000 discharge cell) for various elements. The RSFs were calculated

  19. 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 ?=2.0 ?s. 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 (?=0.5 ?s) standard deviations of ?L=0.072 mm at ~5.5 MeV and ?L=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.

  20. Why not only electric discharge but even a minimum charge on the surface of highly sensitive explosives can catalyze their gradual exothermic decomposition and how a cloud of unipolar charged explosive particles turns into ball lightning

    E-print Network

    Oleg Meshcheryakov

    2013-07-17

    Even a single excess electron or ion migrating on the surface of sensitive explosives can catalyze their gradual exothermic decomposition. Mechanisms underlying such a charge-induced gradual thermal decomposition of highly sensitive explosives can be different. If sensitive explosive is a polar liquid, intense charge-dipole attraction between excess surface charges and surrounding explosive molecules can result in repetitive attempts of solvation of these charges by polar explosive molecules. Every attempt of such uncompleted nonequilibrium solvation causes local exothermic decomposition of thermolabile polar molecules accompanied by further thermal jumping unsolvated excess charges to new surface sites. Thus, ionized mobile hot spots emerge on charged explosive surface. Stochastic migration of ionized hot spots on explosive surface causes gradual exothermic decomposition of the whole mass of the polar explosive. The similar gradual charge-catalyzed exothermic decomposition of both polar and nonpolar highly sensitive explosives can be also caused by intense charge-dipole attacks of surrounding water vapor molecules electrostatically attracted from ambient humid air and strongly accelerated towards charged sites on explosive surfaces. Emission of electrons, photons and heat from ionized hot spots randomly migrating on charged surface of highly sensitive explosive aerosol nanoparticles converts such particles into the form of short-circuited thermionic nanobatteries.

  1. Gated charged-particle trap

    DOEpatents

    Benner, W.H.

    1999-03-09

    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. 5 figs.

  2. Codelivery of antitumor drug and gene by a pH-sensitive charge-conversion system.

    PubMed

    Guan, Xiuwen; Li, Yanhui; Jiao, Zixue; Lin, Lin; Chen, Jie; Guo, Zhaopei; Tian, Huayu; Chen, Xuesi

    2015-02-11

    In the present study, a gene and drug codelivery system was developed by electrostatic binding of polyethylenimine-poly(l-lysine)-poly(l-glutamic acid) (PELG), polyethylenimine (PEI), cis-aconityl-doxorubicin (CAD), and DNA. Zeta potential and drug release analysis confirmed the pH-responsive charge conversion and acid-sensitive drug release functional properties of the PELG/PEI/(DNA+CAD) system. Gel retardation assay and transfection experiment showed the codelivery system had effective DNA binding ability and good transfection efficiency on HepG2 cells. The therapeutic gene p53 was further employed to study its combinational effects with CAD. Cytotoxicity assay showed the half inhibitory concentration (IC50) of the PELG/PEI/(p53+CAD) codelivery system was lower than that of the gene or the drug delivery system. Confocal laser scanning microscopy (CLSM) showed that the drug and gene could be delivered into the cells simultaneously. A significant increase of p53 gene expression was achieved after HepG2 cells treated by PELG/PEI/(p53+CAD) codelivery system. The apoptosis experiment indicated clearly that the codelivery system could lead an effective apoptosis on tumor cells, which was beneficial for the treatment of cancer. The biodistribution and tumor accumulation of the codelivery system was explored via in vivo imaging in subcutaneous xenograft and in situ tumor models. The tumor and some major organs were excised and imaged, and the results showed that the codelivery system can accumulate efficiently in tumor for both tumor models. It can be suggested from the above results that the PELG/PEI/(DNA+CAD) codelivery system will have great potential applications in cancer therapy. PMID:25581567

  3. Differential transimpedance amplifier circuit for correlated differential amplification

    DOEpatents

    Gresham, Christopher A. (Albuquerque, NM); Denton, M. Bonner (Tucson, AZ); Sperline, Roger P. (Tucson, AZ)

    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.

  4. 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.

  5. 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

  6. Bidirectional amplifier

    DOEpatents

    Wright, James T. (Cedarcrest, NM)

    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.

  7. Dual-pH Sensitive Charge-Reversal Polypeptide Micelles for Tumor-Triggered Targeting Uptake and Nuclear Drug Delivery.

    PubMed

    Han, Shi-Song; Li, Ze-Yong; Zhu, Jing-Yi; Han, Kai; Zeng, Zheng-Yang; Hong, Wei; Li, Wen-Xin; Jia, Hui-Zhen; Liu, Yun; Zhuo, Ren-Xi; Zhang, Xian-Zheng

    2015-06-01

    A novel dual-pH sensitive charge-reversal strategy is designed to deliver antitumor drugs targeting to tumor cells and to further promote the nuclei internalization by a stepwise response to the mildly acidic extracellular pH (?6.5) of a tumor and endo/lysosome pH (?5.0). Poly(l-lysine)-block-poly(l-leucine) diblock copolymer is synthesized and the lysine amino residues are amidated by 2,3-dimethylmaleic anhydride to form ?-carboxylic amide, making the polypeptides self-assemble into negatively charged micelles. The amide can be hydrolyzed when exposed to the mildly acidic tumor extracellular environment, which makes the micelles switch to positively charged and they are then readily internalized by tumor cells. A nuclear targeting Tat peptide is further conjugated to the polypeptide via a click reaction. The Tat is amidated by succinyl chloride to mask its positive charge and cell-penetrating function and thus to inhibit nonspecific cellular uptake. After the nanoparticles are internalized into the more acidic intracellular endo/lysosomes, the Tat succinyl amide is hydrolyzed to reactivate the Tat nuclear targeting function, promoting nanoparticle delivery into cell nuclei. This polypeptide nanocarrier facilitates tumor targeting and nuclear delivery simultaneously by simply modifying the lysine amino residues of polylysine and Tat into two different pH-sensitive ?-carboxylic amides. PMID:25626995

  8. 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.…

  9. Chicago Amplified

    NSDL National Science Digital Library

    From the Chicago Public Library to the Lyric Opera, the Chicago Amplified program based at Chicago Public Radio brings the best and the brightest from the Chicago region to anyone with an Internet connection. The program was started in 2006, and visitors can browse past programs all the way back to that year. Clicking on each program will allow users to read a description of the show's content and listen to audio online.

  10. Integrating a redox-coupled dye-sensitized photoelectrode into a lithium-oxygen battery for photoassisted charging.

    PubMed

    Yu, Mingzhe; Ren, Xiaodi; Ma, Lu; Wu, Yiying

    2014-01-01

    With a high theoretical specific energy, the non-aqueous rechargeable lithium-oxygen battery is a promising next-generation energy storage technique. However, the large charging overpotential remains a challenge due to the difficulty in electrochemically oxidizing the insulating lithium peroxide. Recently, a redox shuttle has been introduced into the electrolyte to chemically oxidize lithium peroxide. Here, we report the use of a triiodide/iodide redox shuttle to couple a built-in dye-sensitized titanium dioxide photoelectrode with the oxygen electrode for the photoassisted charging of a lithium-oxygen battery. On charging under illumination, triiodide ions are generated on the photoelectrode, and subsequently oxidize lithium peroxide. Due to the contribution of the photovoltage, the charging overpotential is greatly reduced. The use of a redox shuttle to couple a photoelectrode and an oxygen electrode offers a unique strategy to address the overpotential issue of non-aqueous lithium-oxygen batteries and also a distinct approach for integrating solar cells and batteries. PMID:25277368

  11. Reactions in microemulsions. V. Effect of surface charge and reaction products on a chlorin-sensitized photoreaction

    SciTech Connect

    Jones, C.A.; Weaner, L.E.; Mackay, R.A.

    1980-06-12

    The kinetics of the chlorin-(chlorophyll a and pheophytin a) sensitized photoreduction of methyl red by ascorbate has been examined in oil-in-water microemulsions of three surfactant charge types: anionic, neutral, and cationic. In all cases, the reaction remains zero order in oxidant and exhibits saturation (limiting quantum yield) at high reductant concentration. When a pH 7 buffer is employed as the aqueous phase, the limiting quantum yield decreases in the order anionic > neutral > cationic. However, the reverse order obtains for the initial increase of quantum yield with ascorbate concentration. In both cases, the results are ascribed primarily to the effect of surface charge on local concentrations of ionic species (hydrogen ion and ascorbate monoanion), although there does appear to be some contribution from nonelectrostatic effects. One of the products of the chemical reduction of methyl red, N,N-dimethyl-p-phenylenediamine, has been found to increase quantum yield two- to threefold.

  12. Three dimensional indium-tin-oxide nanorod array for charge collection in dye-sensitized solar cells.

    PubMed

    Lee, Byunghong; Guo, Peijun; Li, Shi-Qiang; Buchholz, D Bruce; Chang, Robert P H

    2014-10-22

    In this article, we report the design, fabrication, characterization, and simulation of three-dimensional (3D) dye-sensitized solar cells (DSSCs), using ordered indium-tin-oxide (ITO) nanorod (NR) arrays as the photoanode, and compare them with conventional planar (2D) DSSCs. The ITO NR array used in the 3D cell greatly improves its performance by providing shorter electron pathways and reducing the recombination rate of the photogenerated electrons. We observed a 10-20% enhancement of the energy conversion efficiency, primarily due to an increased short circuit current. This finding supports the concept of using 3D photoanodes with optically transparent and conducting nanorods for the enhancement of the energy-harvesting devices that require short charge collection distance without sacrificing the optical thickness. Thus, unlike the conventional solar cell structure, the functions for photon collection and charge transport are decoupled to allow for improved cell designs. PMID:25147966

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

    E-print Network

    Golovchenko, Jene A.

    ­5 The inherent noise of such devices is important yet few studies have addressed noise issues,6­9 and these have 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

  14. Charge Transfer Induced Multifunctional Transitions with Sensitive Pressure Manipulation in a Metal-Organic Framework.

    PubMed

    Yang, Junye; Zhou, Long; Cheng, Jinguang; Hu, Zhiwei; Kuo, Changyang; Pao, Chih-Wen; Jang, Lingyun; Lee, Jyh-Fu; Dai, Jianhong; Zhang, Sijia; Feng, Shaomin; Kong, Panpan; Yuan, Zhen; Yuan, Jie; Uwatoko, Yoshiya; Liu, Tao; Jin, Changqing; Long, Youwen

    2015-07-01

    The metal-organic framework {[Fe(2,2'-bipyridine)(CN)4]2Co(4,4'-bipyridine)}·4H2O (Fe2Co-MOF) with single-chain magnetism undergoes an intermetallic charge transfer that converts the Fe2Co charge/spin configurations from Fe(3+)LS-Co(2+)HS-Fe(3+)LS to Fe(2+)LS-Co(3+)LS-Fe(3+)LS (LS = low spin, HS = high spin) around 220 K under ambient pressure. A series of coherent phase transitions in structure, magnetism, permittivity and ferroelectricity are found to take place accompanying with the charge transfer, making Fe2Co-MOF a unique ferroelectric single-chain magnet at low temperature. Moreover, our detailed measurements of magnetization, dielectric constant, and Raman scattering under high pressures illustrate that the charge transfer as well as the resulting multifunctional transitions can be readily induced to occur at room temperature by applying a tiny external pressure of about 0.5 kbar. The present study thus provides a pressure well-controllable multifunctional material with potential applications in a broad temperature region across room temperature. PMID:26083272

  15. High Speed Multichannel Charge Sensitive Data Acquisition System With Self-Triggered Event Timing

    Microsoft Academic Search

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

    2009-01-01

    A number of modern experiments require simultaneous measurement of charges on multiple channels at > MHz event rates with an accuracy of 100-1000 e- mis. 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

  16. Micrometre resolution of a charge integrating microstrip detector with single photon sensitivity.

    PubMed

    Schubert, A; Bergamaschi, A; David, C; Dinapoli, R; Elbracht-Leong, S; Gorelick, S; Graafsma, H; Henrich, B; Johnson, I; Lohmann, M; Mozzanica, A; Radicci, V; Rassool, R; Schädler, L; Schmitt, B; Shi, X; Sobott, B

    2012-05-01

    A synchrotron beam has been used to test the spatial resolution of a single-photon-resolving integrating readout-chip coupled to a 320?µm-thick silicon strip sensor with a dedicated readout system. Charge interpolation methods have yielded a spatial resolution of ?(x) ? 1.8?µm for a 20?µm-pitch strip. PMID:22514170

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

    SciTech Connect

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

  18. How well can Charge Transfer Inefficiency be corrected? A parameter sensitivity study for iterative correction

    E-print Network

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

    2015-01-01

    Radiation damage to space-based Charge-Coupled Device (CCD) 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 degrade measurements of photometry and morphology. As a concrete application, we simulate $1.5\\times10^{9}$ "worst case" galaxy and $1.5\\times10^{8}$ 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, $99.68$ % of spurious ellipticity is corrected in our setup. This is because readout noise is not subject to CTI,...

  19. High-surface-area architectures for improved charge transfer kinetics at the dark electrode in dye-sensitized solar cells.

    PubMed

    Hoffeditz, William L; Katz, Michael J; Deria, Pravas; Martinson, Alex B F; Pellin, Michael J; Farha, Omar K; Hupp, Joseph T

    2014-06-11

    Dye-sensitized solar cell (DSC) redox shuttles other than triiodide/iodide have exhibited significantly higher charge transfer resistances at the dark electrode. This often results in poor fill factor, a severe detriment to device performance. Rather than moving to dark electrodes of untested materials that may have higher catalytic activity for specific shuttles, the surface area of platinum dark electrodes could be increased, improving the catalytic activity by simply presenting more catalyst to the shuttle solution. A new copper-based redox shuttle that experiences extremely high charge-transfer resistance at conventional Pt dark electrodes yields cells having fill-factors of less than 0.3. By replacing the standard Pt dark electrode with an inverse opal Pt electrode fabricated via atomic layer deposition, the dark electrode surface area is boosted by ca. 50-fold. The resulting increase in interfacial electron transfer rate (decrease in charge-transfer resistance) nearly doubles the fill factor and therefore the overall energy conversion efficiency, illustrating the utility of this high-area electrode for DSCs. PMID:24828106

  20. Charge dynamics in new architectures for dye-sensitized solar cells

    Microsoft Academic Search

    Alex Brandon Fletcher Martinson

    2008-01-01

    The promise of a clean, renewable, and abundant energy supply make the efficient conversion of solar energy to electricity a compelling scientific and societal goal. In the following chapters, I will describe my efforts to advance one class of photovoltaic technology, dye-sensitized solar cells, by demonstration and characterization of unexplored device architectures. Chapter 1 provides an introduction to the origin

  1. Is the charge transport in dye-sensitized solar cells really understood?

    PubMed

    Marlow, Frank; Hullermann, Abigail; Messmer, Lisanne

    2015-04-17

    Electrical transients following laser excitation of dye-sensitized solar cells, thus far described by a complex model in the literature, are not consistent with this model. In particular, there are always delays of the electrical signal after the laser pulse. Although the correct theory has not yet been found, the present article is a step toward an improved understanding. PMID:25735542

  2. Charge collection and pore filling in solid-state dye-sensitized solar cells

    Microsoft Academic Search

    Henry J. Snaith; Robin Humphry-Baker; Peter Chen; Ilkay Cesar; Shaik M. Zakeeruddin; Michael Grätzel

    2008-01-01

    The solar to electrical power conversion efficiency for dye-sensitized solar cells (DSCs) incorporating a solid-state organic hole-transporter can be over 5%. However, this is for devices significantly thinner than the optical depth of the active composites and by comparison to the liquid electrolyte based DSCs, which exhibit efficiencies in excess of 10%, more than doubling of this efficiency is clearly

  3. High-speed high-voltage amplifier

    Microsoft Academic Search

    A. N. Dyachko; V. N. Ilyushenko; V. I. Tuyev

    1986-01-01

    A high speed amplifier of high voltage pulse signals coming from remote sources over long transmission lines is now available, specifically designed for increasing the sensitivity of 6 LOR-02 oscillographs. It includes a line attenuation compensator, besides the amplifier stage with a main output and an output for oscillograph synchronization. Each component can be used independently for any particular other

  4. Position and time sensitive photon counting detector with image charge delay-line readout

    NASA Astrophysics Data System (ADS)

    Czasch, Achim; Dangendorf, Volker; Milnes, James; Schössler, Sven; Lauck, Ronald; Spillmann, Uwe; Howorth, Jon; Jagutzki, Ottmar

    2007-09-01

    We have developed single photon counting image intensifier tubes combining position and time information read-out with at least 500x500 pixels and sub-nanosecond time resolution. This image intensifier type uses a resistive screen instead of a phosphor screen and the image charge pickup anode is placed outside the sealed tube. We present a novel delay-line anode design which allows for instance detecting simultaneously arriving pairs of photons. Due to the very low background this technique is suited for applications with very low light intensity and especially if a precise time tagging for each photon is required. We show results obtained with several anode types on a 25 mm image intensifier tube and a 40 mm open-face MCP detector and discuss the performance in neutron radiography, e.g. for homeland security, and the prospects for applications like Fluorescence Life-time Imaging Microscopy (FLIM), astronomy and X-ray polarimetry.

  5. 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.

  6. 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 [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

    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.

  7. Semiconductor hierarchically structured flower-like clusters for dye-sensitized solar cells with nearly 100% charge collection efficiency

    NASA Astrophysics Data System (ADS)

    Xin, Xukai; Liu, Hsiang-Yu; Ye, Meidan; Lin, Zhiqun

    2013-10-01

    By combining the ease of producing ZnO nanoflowers with the advantageous chemical stability of TiO2, hierarchically structured hollow TiO2 flower-like clusters were yielded via chemical bath deposition (CBD) of ZnO nanoflowers, followed by their conversion into TiO2 flower-like clusters in the presence of TiO2 precursors. The effects of ZnO precursor concentration, precursor amount, and reaction time on the formation of ZnO nanoflowers were systematically explored. Dye-sensitized solar cells fabricated by utilizing these hierarchically structured ZnO and TiO2 flower clusters exhibited a power conversion efficiency of 1.16% and 2.73%, respectively, under 100 mW cm-2 illumination. The intensity modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) studies suggested that flower-like structures had a fast electron transit time and their charge collection efficiency was nearly 100%.

  8. A Highly Sensitive Potentiometric Strip-Test for Detecting High Charge Density Impurities in Heparin

    PubMed Central

    Kang, Youngjea; Gwon, Kihak; Shin, Jae Ho; Nam, Hakhyun; Meyerhoff, Mark E.; Cha, Geun Sig

    2015-01-01

    Contamination of heparin with oversulfated chondroitin sulfate (OSCS) became a matter of grave concern in the medical field after many fatal responses to OSCS tainted heparin products occurred during the 2007 – 2008 period. Even though standard lab-based analytical techniques such as nuclear magnetic resonance (NMR) and strong anion-exchange high performance liquid chromatography (SAX-HPLC) have proven useful for monitoring the OSCS content in heparin products, an easy-to-use, quick, portable, and cost-efficient method is still needed for on-site monitoring during and after the heparin production. In this report, a disposable strip-type electrochemical polyion sensor is described for detection of low levels of OSCS contamination in heparin. A magnetic actuator is incorporated into this simple electrode-based microfluidic device in order to create the mixing effect necessary to achieve equilibrium potential changes of the sensor within a microfluidic channel. The planar membrane electrode detector within the sample channel is prepared with a tridodecylmethylammonium chloride (TDMAC)-doped PVC membrane essentially equivalent to previously reported polyanion-sensitive electrodes. When the concentration of heparin applied to the single-use strip device is 57 mg/mL (in only 20 ?l of sample), the same concentration recommended in the NMR analysis protocol for detecting OSCS in heparin, the detection limit is 0.005 wt% of OSCS, which is ca. 20 times lower than the reported detection limit of the NMR method. PMID:21500820

  9. Simulation and modelling of charge transport in dye-sensitized solar cells based on carbon nano-tube electrodes

    NASA Astrophysics Data System (ADS)

    Gacemi, Yahia; Cheknane, Ali; Hilal, Hikmat S.

    2013-03-01

    For a better understanding of the mechanisms of dye-sensitized solar cells (DSSCs), based on carbon nano-tube (CNT) electrodes, a phenomenological model is proposed. For modelling purposes, the meso-scopic porous CNT electrode is considered as a homogeneous nano-crystalline structure with thickness L. The CNT electrode is covered with light-absorbing dye molecules, and interpenetrated by the tri-iodide (I-/I3-) redox couple. A simulation platform, designed to study coupled charge transport in such cells, is presented here. The work aims at formulating a mathematical model that describes charge transfer and charge transport within the porous CNT window electrode. The model is based on a pseudo-homogeneous active layer using drift-diffusion transport equations for free electron and ion transport. Based on solving the continuity equation for electrons, the model uses the numerical finite difference method. The numerical solution of the continuity equation produces current-voltage curves that fit the diode equation with an ideality factor of unity. The calculated current-voltage (J-V) characteristics of the illuminated idealized DSSCs (100 mW cm-2, AM1.5), and the different series resistances of the transparent conductor oxide (TCO) layer were introduced into the idealized simulated photo J-V characteristics. The results obtained are presented and discussed in this paper. Thus, for a series resistance of 4 ? of the TCO layer, the conversion efficiency (?) was 7.49% for the CNT-based cell, compared with 6.11% for the TiO2-based cell. Two recombination kinetic models are used, the electron transport kinetics within the nano-structured CNT film, or the electron transfer rate across the CNT-electrolyte interface. The simulations indicate that both electron and ion transport properties should be considered when modelling CNT-based DSSCs and other similar systems. Unlike conventional polycrystalline solar cells which exhibit carrier recombination, which limits their efficiency, the CNT matrix (in CNT-based cells) serves as the conductor for majority carriers and prevents recombination. This is because of special conductivity and visible-near-infrared transparency of the CNT. Charge transfer mechanisms within the porous CNT matrix and at the semiconductor-dye-electrolyte interfaces are described in this paper.

  10. Sensitivity of HCN channel deactivation to cAMP is amplified by an S4 mutation combined with activation mode shift

    Microsoft Academic Search

    Nadine L. Wicks; Kerry S. C. Chan; Zarina Madden; Bina Santoro; Edgar C. Young

    2009-01-01

    Hyperpolarisation–activation of HCN ion channels relies on the movement of a charged S4 transmembrane helix, preferentially\\u000a stabilising the open conformation of the ion pore gate. The open state is additionally stabilised, (a) when cyclic AMP (cAMP)\\u000a is bound to a cytoplasmic C-terminal domain or (b) when the “mode I” open state formed initially by gate opening undergoes\\u000a a “mode shift”

  11. Charge collection and absorption-limited sensitivity of x-ray photoconductors: Applications to a-Se and HgI2

    NASA Astrophysics Data System (ADS)

    Kabir, M. Zahangir; Kasap, S. O.

    2002-03-01

    A generalized expression for charge carrier transport and absorption-limited sensitivity of x-ray photoconductors is derived by analytically solving the continuity equation for both holes and electrons considering the drift of electrons and holes in the presence of deep traps. The normalized sensitivity equation is applied to stabilized a-Se and HgI2. In the latter case, the sensitivity model is fitted to published data to determine the electron and hole ranges (6.4×10-6 cm2/V and 7×10-8 cm2/V, respectively) in screen-printed polycrystalline HgI2.

  12. Modulated charge injection in p-type dye-sensitized solar cells using fluorene-based light absorbers.

    PubMed

    Liu, Zonghao; Xiong, Dehua; Xu, Xiaobao; Arooj, Qudsia; Wang, Huan; Yin, Liyuan; Li, Wenhui; Wu, Huaizhi; Zhao, Zhixin; Chen, Wei; Wang, Mingkui; Wang, Feng; Cheng, Yi-Bing; He, Hongshan

    2014-03-12

    In this study, new pull-push arylamine-fluorene based organic dyes zzx-op1, zzx-op2, and zzx-op3 have been designed and synthesized for p-type dye-sensitized solar cells (p-DSCs). In zzx-op1, a di(p-carboxyphenyl)amine (DCPA) was used as an electron donor, a perylenemonoimide (PMID) as an electron acceptor, and a fluorene (FLU) unit with two aliphatic hexyl chains as a ?-conjugated linker. In zzx-op2 and zzx-op3, a 3,4-ethylenedioxythiophene (EDOT) and a thiophene were inserted consecutively between PMID and FLU to tune the energy levels of the frontier molecular orbitals of the dyes. The structural modification broadened the spectral coverage from an onset of 700 nm for zzx-op1 to 750 nm for zzx-op3. The electron-rich EDOT and thiophene lifted up the HOMO (highest occupied molecular orbital) levels of zzx-op2 and zzx-op3, making their potential more negative than zzx-op1. When three dyes were employed in p-type DSCs with I(-)/I3(-) as a redox couple and NiO nanoparticles as hole materials, zzx-op1 exhibited impressive energy conversion efficiency of 0.184% with the open-circuit voltage (VOC) of 112 mV and the short-circuit current density (JSC) of 4.36 mA cm(-2) under AM 1.5G condition. Density functional theory calculations, transient photovoltage decay measurements, and electrochemical impedance spectroscopic studies revealed that zzx-op1 sensitized solar cell exhibited much higher charge injection efficiency (90.3%) than zzx-op2 (53.9%) and zzx-op3 (39.0%), indicating a trade-off between spectral broadening and electron injection driving force in p-type DSCs. PMID:24521135

  13. 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.

  14. Efficient triarylamine-perylene dye-sensitized solar cells: influence of triple-bond insertion on charge recombination.

    PubMed

    Yan, Cancan; Ma, Wentao; Ren, Yameng; Zhang, Min; Wang, Peng

    2015-01-14

    We synthesize two new metal-free donor-acceptor organic dyes (C266 and C267) featuring a N-annulated perylene block. Owing to the improved coplanarity of conjugated units as well as the prolonged conjugation upon inserting a triple bond between the triarylamine and perylene segments, the C267 dye exhibits a slightly red-shifted absorption peak and an enhanced maximum molar absorption coefficient with respect to its reference dye C266, leading to an improved photocurrent output in dye-sensitized solar cells. However, the triple-bond introduction also brings forth an over 100 mV reduced open-circuit photovoltage owing to faster interfacial charge recombination, which presents a clear correlation with a reduced mean thickness of self-assembled dye layer on titania as revealed by X-ray reflectivity measurements. The C266 dye, albeit with a relatively weaker light-harvesting capacity, displays a higher power conversion efficiency of 9.0% under the 100 mW cm(-2), simulated AM1.5G sunlight. PMID:25493711

  15. Semiconductor hierarchically structured flower-like clusters for dye-sensitized solar cells with nearly 100% charge collection efficiency.

    PubMed

    Xin, Xukai; Liu, Hsiang-Yu; Ye, Meidan; Lin, Zhiqun

    2013-11-21

    By combining the ease of producing ZnO nanoflowers with the advantageous chemical stability of TiO2, hierarchically structured hollow TiO2 flower-like clusters were yielded via chemical bath deposition (CBD) of ZnO nanoflowers, followed by their conversion into TiO2 flower-like clusters in the presence of TiO2 precursors. The effects of ZnO precursor concentration, precursor amount, and reaction time on the formation of ZnO nanoflowers were systematically explored. Dye-sensitized solar cells fabricated by utilizing these hierarchically structured ZnO and TiO2 flower clusters exhibited a power conversion efficiency of 1.16% and 2.73%, respectively, under 100 mW cm(-2) illumination. The intensity modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) studies suggested that flower-like structures had a fast electron transit time and their charge collection efficiency was nearly 100%. PMID:24081015

  16. Charge integrating type position-sensitive proportional chamber for time-resolved measurements using intense X-ray sources

    NASA Astrophysics Data System (ADS)

    Mochiki, Koh-ichi; Hasegawa, Ken-ichi

    1985-02-01

    A position-sensitive detecting system for time-resolved diffraction measurements with very intensive X-ray sources has been developed. It consists of a charge integrating type gas-filled detector, multichannel analog multiplexers, a signal processor and a memory (120 ch.×128 phases×24 bits). The detector is 120 mm long in effective length by 10 mm×10 mm in cross section with a single anode of 20 ?m diameter. One of the cathode planes consists of 120 cathode strips with a pitch of 1 mm. The spatial resolution is equal to the pitch under a certain detector current limit. The gas gain is adjustable to an appropriate value according to the X-ray intensity range of interest. For experiments with 8 keV X-ray sources, maximum absorption rates of 9×10 7 photons/s·mm with low applied voltage and minimum absorption rates of about 3 photons/s·mm with high applied voltage can be achieved. This system was applied to a time-resolved X-ray diffraction study on frog muscle using a synchrotron radiation source at the Photon Factory and we could collect diffraction patterns with a time resolution of 10 ms and only 10 stimulations.

  17. Development of a Highly Sensitive Genus-Specific Quantitative Reverse Transcriptase Real-Time PCR Assay for Detection and Quantitation of Plasmodium by Amplifying RNA and DNA of the 18S rRNA Genes?

    PubMed Central

    Kamau, Edwin; Tolbert, LaDonna S.; Kortepeter, Luke; Pratt, Michael; Nyakoe, Nancy; Muringo, Linda; Ogutu, Bernard; Waitumbi, John N.; Ockenhouse, Christian F.

    2011-01-01

    A highly sensitive genus-specific quantitative reverse transcriptase real-time PCR (qRT-PCR) assay for detection of Plasmodium has been developed. The assay amplifies total nucleic acids (RNA and DNA) of the 18S rRNA genes with a limit of detection of 0.002 parasite/?l using cultured synchronized ring stage 3D7 parasites. Parasite densities as low as 0.000362 parasite/?l were detected when analyzing clinical samples. Analysis of clinical samples showed that detection of 18S rRNA genes from total nucleic acids increased the analytical sensitivity of the assay by more than 1 log unit compared to DNA only. When clinical samples with no parasites present by microscopy were analyzed by qRT-PCR, 90% (117 of 130) were positive for the presence of Plasmodium nucleic acids. Quantification of clinical samples by qRT-PCR using total nucleic acid versus DNA was compared to microscopy. There was a significantly greater correlation of parasite density to microscopy when DNA alone was used than with total nucleic acid. We conclude that analysis of total nucleic acids by qRT-PCR is a suitable assay for detection of low parasite levels in patients with early-stage malaria and/or submicroscopic infections and could greatly benefit malaria diagnosis, intervention trials, and malaria control and elimination efforts. PMID:21653767

  18. 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

  19. A low noise FET with integrated charge restoration for radiation detectors

    Microsoft Academic Search

    T. Nashoishibi; G. White

    1990-01-01

    A novel pulsed, nonoptical, reset technique for use in charge-sensitive amplifiers and radiation detectors is described. The first-stage FET and charge restoration are integrated into one five-terminal device called the Pentafet. A pulse of minority carriers is injected directly into the channel of the FET. The technique is fast, and there are no aftereffects on the operation of the FET.

  20. 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 ?-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.

  1. Power Amplifier Linearization Techniques

    E-print Network

    Dawson, Joel

    Power Amplifier Linearization Techniques: An Overview Workshop on RF Circuits for 2.5G and 3G(x))) is a linear function of the input variable x. x (Power amplifier) #12;Technique II estimation. · Depends on having a good power amplifier model. · Complexity: incurs power overhead of a DSP

  2. Diode amplifier of modulated optical beam power

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  3. Measurement of Electric Charge of Dust Particles in a Plasma

    NASA Astrophysics Data System (ADS)

    Itoh, Masataka; Nakamura, Yoshiharu

    2000-10-01

    The electric charge of dust particles immersed in a plasma, whose diameters are 5 to 20 microns, were measured. The electric charge of a dust particle was detected by a charge sensitive amplifier, and analyzed with a spectroscopy system. The experimental device was made of Pyrex glass tubes of 15 cm in diameter and was composed of three parts, a dropping system of dust particles, plasma generation part, and measuring part of electric charge. An ultrasonic vibrator drops dust particles from the top part of this device and then they pass through the plasma. The plasma was generated by DC discharge between tungsten filaments and the grounded cage of multi-dipole magnets.The working gas was Argon. The dust particles are found to be negatively charged and their electric charge is about a few ten thousands, and those values are almost in proportion to the diameters of dust particles.

  4. Charge transport properties in dye-sensitized nanostructured TiO{sub 2} thin film electrodes studied by photoinduced current transients

    SciTech Connect

    Solbrand, A.; Henningsson, A.; Soedergren, S.; Lindstroem, H.; Hagfeldt, A.; Lindquist, S.E. [Uppsala Univ. (Sweden)] [Uppsala Univ. (Sweden)

    1999-02-18

    Dye-sensitized nanostructured TiO{sub 2} is a promising material for solar cell applications since it is expected to be produced at a relatively low cost and can give efficiencies of up to 10%. The charge transport in dye-sensitized nanostructured TiO{sub 2} was studied by laser pulse induced photocurrent transients. The experimental curves were compared to simulations using a diffusion model with an initial electron distribution of an exponential decay. The simulations were optimized with respect to the experimental curves giving an apparent diffusion coefficient of 6 {times} 10{sup {minus}6} cm{sup 2}/s for the electrons with an electrolyte of 0.1 M KI in propylene carbonate, the potential being +300 mV vs Ag/AgCl in ethanol. The charge transport was highly dependent on electrolyte composition and light intensity.

  5. High-Surface-Area Architectures for Improved Charge Transfer Kinetics at the Dark Electrode in Dye-Sensitized Solar Cells

    E-print Network

    ABSTRACT: Dye-sensitized solar cell (DSC) redox shuttles other than triiodide/iodide have exhibited: dark electrode, inverse opal, dye cell, fill factor INTRODUCTION Dye-sensitized solar cells (DSCs-Sensitized Solar Cells William L. Hoffeditz,, Michael J. Katz, Pravas Deria, Alex B.F. Martinson,,§ Michael J

  6. Wireless Josephson Amplifier

    E-print Network

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

    2014-07-21

    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 new 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.

  7. Integrated CMOS RF amplifier

    NASA Technical Reports Server (NTRS)

    Charity, C.; Whitaker, S.; Purviance, J.; Canaris, M.

    1990-01-01

    This paper reports an integrated 2.0 micron CMOS RF amplifier designed for amplification in the 420-450 MHz frequency band. Design techniques are shown for the test amplifier configuration. Problems of decreased amplifier bandwidth, gain element instability, and low Q values for the inductors were encountered. Techniques used to overcome these problems are discussed. Layouts of the various elements are described and a summary of the simulation results are included. Test circuits have been submitted to MOSIS for fabrication.

  8. Josephson bifurcation amplifier: Amplifying quantum signals using a dynamical bifurcation

    NASA Astrophysics Data System (ADS)

    Vijayaraghavan, Rajamani

    Quantum measurements of solid-state systems, such as the readout of superconducting quantum bits challenge conventional low-noise amplification techniques. Ideally, the amplifier for a quantum measurement should minimally perturb the measured system while maintaining sufficient sensitivity to overcome the noise of subsequent elements in the amplification chain. Additionally, the drift of materials properties in solid-state systems mandates a fast acquisition rate to permit measurements in rapid succession. In this thesis, we describe the Josephson Bifurcation Amplifier (JBA) which was developed to meet these requirements. The JBA exploits the sensitivity of a dynamical system - a non-linear oscillator tuned near a bifurcation point. In this new scheme, all available degrees of freedom in the dynamical system participate in information transfer and none contribute to unnecessary dissipation resulting in excess noise. We have used a superconducting tunnel junction, also known as a Josephson junction to construct our non-linear oscillator. The Josephson junction is the only electronic circuit element which remains non-linear and non-dissipative at arbitrarily low temperatures. This thesis will describe the theory and experiments demonstrating bifurcation amplification in the JBA and its application to the measurement of superconducting quantum bits. By describing the JBA as a parametrically driven oscillator, we will demonstrate that the ultimate sensitivity of the JBA is limited only by quantum fluctuations. Using this treatment, we will identify the connection between the four main aspects of working with a dynamical bifurcation: parametric amplification, squeezing, quantum activation and the Dynamical Casimir Effect.

  9. Noiseless Optical Amplifier Operating on Hundreds of Spatial Modes

    NASA Astrophysics Data System (ADS)

    Corzo, N. V.; Marino, A. M.; Jones, K. M.; Lett, P. D.

    2012-07-01

    We implement a noiseless optical amplifier using a phase-sensitive four-wave mixing process in rubidium vapor. We observe performance near the quantum limit for this type of amplifier over a range of experimental parameters and show that the noise figure is always better than would be obtained with a phase-insensitive amplifier with the same gain. Additionally, we observe that the amplifier supports hundreds of spatial modes, making it possible to amplify complex two-dimensional spatial patterns with less than a 10% degradation of the input signal-to-noise ratio for gains up to 4.6. To confirm the multimode character of the amplifier, we study the noise figure as a function of spatially-varying losses. Additionally, we investigate the spatial resolution of the amplifier and show that it supports a range of spatial frequencies from 1.3 to more than 35 line pairs per millimeter.

  10. Double conjugate laser amplifier

    SciTech Connect

    Chandra, S.; Daunt, G.H.

    1991-01-29

    This paper describes a double conjugate laser amplifier system for producing a stable output laser beam in line with a laser oscillator input beam. It comprises: a laser oscillator which produces a low energy oscillator laser beam therefrom directly along a laser beam axis of the system; an amplification means comprised of double conjugate laser amplifiers further comprised of a first and a second singly phase conjugate amplifiers laterally opposite each other about the laser beam axis; polarizers with one of the polarizers positioned between each of the first and second singly phase conjugate amplifiers on the laser beam axis; Pockels cells with on of the Pockels cells positioned on the laser beam axis immediately prior to one of the polarizers; and a means for selectively switching the amplifier means comprised of applying a half-wave voltage at each of the Pockels cells to provide a polarization rotation of the input beam through 90{degrees} for routing of the oscillator laser beam directly through or reflected off the polarizes as an input beam to the amplification means wherein the amplification means amplifies the input beam twice in each of the first and second singly phase conjugate amplifiers and reflects the amplified laser beam off the polarizers as an amplified laser output beam in exactly the same direction as the input laser beam.

  11. Sensitive determination of four tetracycline antibiotics in pig plasma by field-amplified sample stacking open-tubular capillary electrochromatography with dimethylethanolamine aminated polychloromethyl styrene nano-latex coated capillary column.

    PubMed

    Guo, Yaxiao; Meng, Lei; Zhang, Yanhao; Tang, Wei; Zhang, Wenfen; Xia, Yan; Ban, Fuguo; Wu, Ningpeng; Zhang, Shusheng

    2013-12-30

    This paper described the preparation and application of a new dimethylethanolamine aminated polychloromethyl styrene nano-latex (DMEAPL) coated capillary column (ccc-DMEAPL) in the determination of four tetracycline antibiotics (TCA) including tetracycline (TC), oxytetracycline (OTC), doxycycline (DC) and chlorotetracycline (CTC) in pig plasma. The ccc-DMEAPL column was characterized with steady EOF values of ca. 1.5-5.2×10(-5)cm(2)/Vs at pH 1.8-6.3. The optimized conditions for field-amplified sample stacking open-tubular capillary electrochromatography (FASS-OT-CEC) were as following: background electrolyte, 10mmol/L Na2HPO4+15mmol/L citric acid (pH 3.2); ccc-DMEAPL, 50?m i.d.×50cm (effective length 41.5cm), separation voltage, 18kV; column temperature, 25°C; UV detection wavelength, 270nm; water-plug injection: 30mbar×10s; sample electrokinetic injection, 10kV×20s. The four TCA were extracted with the solution of 10mmol/L Na2HPO4+15mmol/L citric acid+4g/L EDTA-2Na (pH 3.2). The FASS-OT-CEC method was validated in terms of linearity, sensitivity, selectivity, precision and accuracy. The LODs ranged from 3 to 7ng/mL, the recoveries for the four TCA were all more than 80%. The developed method was successfully applied for the determination of TCs in the actual pig plasma samples. PMID:24269909

  12. Structure-property relationships for three indoline dyes used in dye-sensitized solar cells: TDDFT study of visible absorption and photoinduced charge-transfer processes.

    PubMed

    Li, Huixing; Chen, Maodu

    2013-12-01

    The electronic structures of three D-A-?-A indoline dyes (WS-2, WS-6, and WS-11) used in dye-sensitized solar cells (DSSCs) were studied by performing quantum chemistry calculations. The coplanarity of the A-?-A segment and distinct noncoplanarity of the indoline donor part of each dye were confirmed by checking the calculated geometric parameters. The relationships between molecular modifications and the optical properties of the dyes were derived in terms of the partial density of states, absorption spectrum, frontier molecular orbital, and excited-state charge transfer. 3D real-space analysis of the transition density (TD) and charge difference density (CDD) was also performed to further investigate the excited-state features of the molecular systems, as they provide visualized physical pictures of the charge separation and transfer. It was found that modifying the alkyl chain of the bridge unit near the acceptor unit is an efficient way to decrease dye aggregation and improve DSSC efficiency. Inserting a hexylthiophene group next to the donor unit leads to a complicated molecular structure and a decrease in the charge-transfer ability of the system, which has an unfavorable impact on DSSC performance. PMID:24154611

  13. CMOS distributed amplifiers

    Microsoft Academic Search

    Juan C. Ranuárez; Yogesh K. Ramadass; M. Jamal Deen

    2004-01-01

    This paper reviews the characteristics of broadband distributed amplifiers (DA) and traveling wave amplifiers (TWA) implemented in CMOS technology. The basic equations that govern the performance and design of DAs in terms of gain, bandwidth, matching and noise are summarized, as well as the implications of the use of transmission lines to replace on-chip inductors. The difficulties that arise for

  14. Receiver Video Transistor Amplifiers

    Microsoft Academic Search

    R. G. Salaman

    1958-01-01

    The development of the transistor has progressed to the point where practical video amplifiers of quality comparable to those of vacuum tubes can be designed. Limitations such as collector-emitter voltage, power, and alpha cut-off frequency continue to pose problems in designing a one stage video amplifier.

  15. 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.

  16. Optoelectronic Microwave Power Amplifiers

    Microsoft Academic Search

    Robert O'Connell; Chih-Jung Huang; Armin Karabegovic; William Nunnally

    2007-01-01

    The power amplifiers used in the transmit\\/receive (TR) modules of future X-band radar systems will be required to be more efficient and compact than currently used circuits. This paper describes a simulation study of optoelectronic (OE) Class AB and Class E microwave power amplifiers based on a novel photoconductive semiconductor switch (PCSS). The simulations show that as the width of

  17. Electron transport in dye-sensitized solar cells based on ZnO nanotubes : evidence for highy efficient charge collection and exceptionally rapiod dynamics.

    SciTech Connect

    Martinson, A. B. F.; Goes, M. S.; Fabregat-Santiago, F.; Bisquert, J.; Pellin, M. J.; Hupp, J. T. (Materials Science Division); (Northwestern Univ.); (Univ. Jaume); (Univ. Estadual Paulista)

    2009-02-01

    Dye-sensitized solar cells based on ordered arrays of polycrystalline ZnO nanotubes, 64 {micro}m in length, are shown to exhibit efficient electron collection over the entire photoanode array length. Electrochemical impedance spectroscopy, open-circuit photovoltage decay analysis, and incident-photon-to-current efficiency spectra are used to quantify charge transport and lifetimes. Despite the relatively thick photoanode, the charge extraction time is found to be faster than observed in traditional TiO{sub 2} nanoparticle photoanodes. If the extraction dynamics are interpreted as diffusive, effective electron diffusion coefficients of up to 0.4 cm{sup 2} s{sup -1} are obtained, making these pseudo-1D photoanodes the fastest reported for an operating DSC to date. Rapid electron collection is of practical significance because it should enable alternative redox shuttles, which display relatively fast electron-interception dynamics, to be employed without significant loss of photocurrent.

  18. 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. (Chemical Sciences and Engineering Division); ( XSD); (Southern Federal Univ.); (Lund Univ.); (Northwestern Univ.)

    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.

  19. Charge and Energy Transfer in the Metal-free Indoline Dyes for Dye-sensitized Solar Cells

    Microsoft Academic Search

    Li-ying Diao; Wen-xiang Gu; Yue-hui Chen; Feng-cai Ma

    2006-01-01

    Metal-free indoline dyes for dye-sensitized solar cells were studied by employing quantum chemistry methods. Comparative study of the properties of both ground and excited states of metal-free indoline dyes for dye- sensitized solar cells revealed: (i) as the number of rhodanine rings increases, the energy difference between HOMO and LUMO decreases and there is a red shift in the absorption

  20. 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.

  1. Noise in chi (3) and photorefractive amplifiers

    NASA Astrophysics Data System (ADS)

    Sternklar, Shmuel; Glick, Yaakov

    1995-12-01

    A comparison of the noise characteristics of chi (3) and photorefractive coherent amplifiers reveals basic differences in their dependence on operating parameters. Unlike all types of chi (3) amplifiers, which are shown to have a well-defined optimum working point in the region of the self-stimulated scattering threshold, the photorefractive amplifier can be made increasingly quieter by lowering the pump power. This is demonstrated by use of highly doped Co:BaTiO3 in a tight-focus reflection grating geometry. It is shown that scattering from inhomogeneities in the crystal is the major limiting noise source and is significantly higher than predictions resulting from fundamental considerations such as random space-charge noise. An extremely high small-signal gain of 107 was measured with this crystal and geometry. To our knowledge this is the highest photorefractive gain reported to date.

  2. Optimizing low-light microscopy with back-illuminated electron multiplying charge-coupled device: enhanced sensitivity, speed, and resolution

    Microsoft Academic Search

    Colin G. Coates; Donal J. Denvir; Noel G. McHale; Keith D. Thornbury; Mark A. Hollywood

    2004-01-01

    Abstract. The back-illuminated electron multiplying charge-coupled device (EMCCD) camera,is having a profound influence on the field of low-light dynamic cellular microscopy, combining highest possible photon,collection efficiency with the ability to virtually eliminate the readout noise detection limit. We report here the use of this camera, in 5123512 frame-transfer chip format at 10-MHz pixel readout speed, in optimizing a demanding ultra-low-light

  3. Anion-correlated conduction band edge shifts and charge transfer kinetics in dye-sensitized solar cells with ionic liquid electrolytes.

    PubMed

    Zhang, Min; Zhang, Jing; Bai, Yu; Wang, Yinghui; Su, Mei; Wang, Peng

    2011-03-01

    In solvent-free ionic liquid electrolytes for efficient dye-sensitized solar cells, iodide and non-iodide melts are ordinarily blended in order to attain a high dynamic fluidity and thereby meet a fast mass transport of electroactive species. This common tactic could bring forth a prominent impact of various anions on cell efficiency by altering photocurrent and/or photovoltage. Herein we report evident effects of the dicyanamide versus tetracyanoborate anion on the energetics of titania conduction band edge and the kinetics of multi-channel charge-transfer reactions in cells employing a high absorption coefficient ruthenium sensitizer C106. A slightly shorter photoluminescence lifetime of C106 grafted on alumina is probed for the tetracyanoborate-based reference cell with respect to the dicyanamide counterpart. However, owing to a more favourable thermodynamic driving force of ?90 meV, the tetracyanoborate anion prompts an almost 3-fold faster electron injection from the excited-state dye to titania than dicyanamide, leading to a higher charge separation yield, which is in good agreement with an almost indistinguishable ratio of external quantum efficiency enhancement in the whole spectral response region. Compared to tetracyanoborate, the presence of dicyanamide at the titania/electrolyte interface evokes a 27-fold smaller interfacial electron exchange rate (K) with triiodide, accounting for the open-circuit photovoltage variation observed in current-voltage measurements. PMID:21184000

  4. Super sensitization: grand charge (hole/electron) separation in ATC dye sensitized CdSe, CdSe/ZnS type-I, and CdSe/CdTe type-II core-shell quantum dots.

    PubMed

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

    2014-10-01

    Ultrafast charge-transfer dynamics has been demonstrated in CdSe quantum dots (QD), CdSe/ZnS type-I core-shell, and CdSe/CdTe type-II core-shell nanocrystals after sensitizing the QD materials by aurin tricarboxylic acid (ATC), in which CdSe QD and ATC form a charge-transfer complex. Energy level diagrams suggest that the conduction and valence band of CdSe lies below the LUMO and the HOMO level of ATC, respectively, thus signifying that the photoexcited hole in CdSe can be transferred to ATC and that photoexcited ATC can inject electrons into CdSe QD, which has been confirmed by steady state and time-resolved luminescence studies and also by femtosecond time-resolved absorption measurements. The effect of shell materials (for both type-I and type-II) on charge-transfer processes has been demonstrated. Electron injection in all the systems were measured to be <150?fs. However, the hole transfer time varied from 900?fs to 6?ps depending on the type of materials. The hole-transfer process was found to be most efficient in CdSe QD. On the other hand, it has been found to be facilitated in CdSe/CdTe type-II and retarded in CdSe/ZnS type-I core-shell materials. Interestingly, electron injection from photoexcited ATC to both CdSe/CdTe type-II and CdSe/ZnS type-I core-shell has been found to be more efficient as compared to pure CdSe QD. Our observation suggests the potential of quantum dot core-shell super sensitizers for developing more efficient quantum dot solar cells. PMID:25179856

  5. Time-Domain ab Initio Study of Charge Relaxation and Recombination in Dye-Sensitized TiO2

    E-print Network

    understanding of these processes is crucial for improving solar cell design and optimizing photovoltaic current with surface hopping in the Kohn-Sham basis. Representing the dye-sensitized semiconductor Gra¨tzel cell with the I- /I3 - mediator, the system addresses the problems of an organic/inorganic, molecule

  6. High performance charge transfer device detectors

    SciTech Connect

    Sweedler, J.V.; Bilhorn, R.B.; Epperson, P.M.; Sims, G.R.; Denton, M.B.

    1988-02-15

    There is great interest in replacing single-channel photomultiplier tubes (PMTs) with multichannel devices (1,2). Multichannel detectors such as vidicons, intensified target vidicons, image dissectors, and photodiode arrays (PDAs) do not offer the sensitivity, dynamic range, and noise performance necessary to be competitive with the PMT in many situations. Successful application of these multichannel detectors is limited to experimental conditions in which the multichannel advantage outweighs the noise, cross talk, and dynamic-range disadvantages. New multichannel alternatives to PMT detection are now capable of superior sensitivity and dynamic range when compared on a detector element by detector element basis. In fact, some of these devices exceed the sensitivity and dynamic range of all other available detectors. The performance of charge transfer devices (CTDs) has advanced to the point where the application of this technology to the field of analytical chemistry is appropriate. In the first of this two-part series, the theory, design, operation, and performance of CTD detectors are described. CTDs are solid-state multichannel detectors. These detectors integrate signal information as light strikes them, much like photographic film. The amount of charge generated in a CTD detector is measured either by moving the charge form the detector element where it is collected to a charge-sensing amplifier, or by moving it within the detector element and measuring the voltage change induced by this movement.

  7. Amplified spontaneous Raman scattering in fiber Raman amplifiers

    Microsoft Academic Search

    Kiyofumi Mochizuki; Noboru Edagawa; Yoshinao Iwamoto

    1986-01-01

    Amplified spontaneous Raman scattered light power in forward and backward Raman amplifiers is theoretically and experimentally studied under the assumption of the constant Raman gain coefficient in the bandwidth of an optical filter. On the basis of the results, the power ratio of the amplified signal to amplified spontaneous scattering is discussed. As a result, it is clarified that the

  8. Amplified spontaneous emission in pulse-pumped Raman amplifiers

    Microsoft Academic Search

    Jake Bromage; P. J. Winzer; L. E. Nelson; M. D. Mermelstein; C. Horn; C. H. Headley

    2003-01-01

    We discuss amplified spontaneous emission (ASE) generated in Raman amplifiers that are counter-pumped with trains of pulses. Our experimental and theoretical results show that if the peak power of the pump pulses is too high, the ASE output from the amplifier can be significantly higher than that from a continuous-wave pumped amplifier providing the same gain. This effect places a

  9. Semiconductor laser amplifier optimization

    SciTech Connect

    Gillner, L.; Goobar, E.; Thylen, L.; Gustavsson, M.

    1989-08-01

    Long-wavelength semiconductor laser amplifiers are investigated with respect to spectral gain properties such as peak gain wavelength shift and width of gain curve, employing different structural parameters such as thickness of the active layer and amplifier length. The model used takes into account Auger recombination, thermal effects, and spontaneous emission. It is shown that there exists an optimum thickness of the active layer with respect to current density for a given gain and that increased length of the amplifier allows higher gains and reduced variation of peak gain wavelength with respect to variation of peak gain at the expense of increased saturation by amplified spontaneous emission and increased excess noise. Finally, an experimental verification of the theoretical model is made.

  10. Amplified DNA Biosensors

    Microsoft Academic Search

    Itamar Willner; Bella Shlyahovsky; Bilha Willner; Maya Zayats

    2009-01-01

    \\u000a Amplified detection of DNA is a central research topic in modern bioanalytical science. Electronic or optical transduction\\u000a of DNA recognition events provides readout signals for DNA biosensors. Amplification of the DNA analysis is accomplished by\\u000a the coupling of nucleic acid-functionalized enzymes or nucleic acid-functionalized nanoparticles (NP) as labels for the DNA\\u000a duplex formation. This chapter discusses the amplified amperometric analysis

  11. Superfunctions for amplifiers

    NASA Astrophysics Data System (ADS)

    Kouznetsov, Dmitrii

    2013-07-01

    An amplifier is characterized by its transfer function T, which expresses the dependence of the output signal on the input signal. This signal may be related to power, intensity, energy of a pulse, or its fluence, or any similar physical quantity. The internal structure of the amplified signal (e.g., its spectral content, polarization, temporal behavior, and spatial distribution) is not taken into account. The amplifier is considered to be spatially homogeneous and uniformly pumped. The transfer function is supposed to be known (measured in an experiment). The problem of reconstruction of the behavior of the signal inside the amplifier is formulated. For a given transfer function T, the evolution of the signal inside is interpreted as the superfunction F, satisfying the transfer equation F( z + 1) T(F(z)), where z is of coordinate along the propagation direction, while the length of the amplifier is used as a unit of measurement. (For simplicity, distances are measured in units of the length of the amplifier.) Two examples of realistic transfer function T are considered; they correspond to amplification of continuous wave and to amplification of pulses. In these examples, the transfer function and the distribution of the signal along the amplifier can be expressed in terms of special functions. The iterative procedure is suggested as a general method of reconstructing the signal along the amplifier, if neither the transfer function T, nor the superfunction F can be expressed with a simple combination of special functions. The examples show that the iterations converge to a physically meaningful solution. This method is expected to be useful for the characterization of laser materials from the measurement of the transfer function of a bulk sample.

  12. A grid amplifier

    Microsoft Academic Search

    M. Kim; J. J. Rosenberg; R. P. Smith; J. B. Hacker; M. P. DeLisio; D. B. Rutledge

    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

  13. Transistorized Distributed Amplifier

    Microsoft Academic Search

    Charles W. McMullen

    1959-01-01

    Some analytical and experimental results are given for a transistorized distributed amplifier using the common emitter configuration. The characteristic impedances of the base and collector transmission lines are both 43.4?. A 4-section amplifier stage yields a mid-frequency gain of 5.1 db and an upper half-power frequency of 290 Mc. The low-frequency response is reasonably constant down to 10 cps.

  14. Transistorized Distributed Amplifier

    Microsoft Academic Search

    Charles W. McMullen

    1959-01-01

    Some analytical and experimental results are given for a transistorized ; distributed amplifier using the common emitter configuration. The characteristic ; impedances of the base and collector transmission lines are both 43.4 OMEGA . A ; 4-section amplifier stage yields a mid-frequency gain of 5.1 db and an upper half-; power frequency of 290 Mc. The low-frequency response is reasonably

  15. Raman amplifiers for telecommunications

    Microsoft Academic Search

    Mohammed N. Islam

    2002-01-01

    Raman amplifiers are being deployed in almost every new long-haul and ultralong-haul fiber-optic transmission systems, making them one of the first widely commercialized nonlinear optical devices in telecommunications. This paper reviews some of the technical reasons behind the wide-spread acceptance of Raman technology. Distributed Raman amplifiers improve the noise figure and reduce the nonlinear penalty of fiber systems, allowing for

  16. Phagocytosis of aged human neutrophils by macrophages is mediated by a novel "charge-sensitive" recognition mechanism.

    PubMed Central

    Savill, J S; Henson, P M; Haslett, C

    1989-01-01

    The removal of neutrophils and their histotoxic contents from the inflamed site is a prerequisite for resolution of tissue injury, and a point at which factors critical to the pathogenesis of chronic inflammation may act. Engulfment of intact, senescent neutrophils by macrophages represents an important neutrophil disposal process. In this study the mechanism by which human monocyte-derived macrophages (M phi) recognized and ingested human neutrophils that had been aged in culture was studied using an in vitro phagocytic assay. Inhibition of M phi receptors for Ig Fc and the opsonic complement fragments C3b and iC3b with MAbs to M phi FcR, CR1, CR3, and CR4 had no effect on recognition, and the pattern of inhibition observed when polyanions were included in the medium at 1 mg/ml was different from that reported for the M phi receptor for protein advanced glycosylation end products (AGE), indicating a recognition mechanism different from those proposed for M phi phagocytosis of senescent erythrocytes. Furthermore, although aging neutrophils undergo programmed cell death (or apoptosis), which is directly related to recognition by M phi, the pattern of inhibition observed with monosaccharides was different from that reported to inhibit the binding of apoptotic mouse thymocytes to isologous M phi. By contrast, evidence was obtained for a novel recognition mechanism inhibitable by cationic sugars and amino acids in a charge-dependent fashion, and directly modulated by pH but not affected by inhibitors of the mannose-6-phosphate, sheep erythrocyte, mannosyl-fucosyl, asialoglycoprotein, and scavenger receptors of the macrophage. These observations suggest that hydrogen ions and charged molecules may modulate M phi uptake of senescent neutrophils at inflamed sites, and that recognition itself may involve charged structures on the cells. Images PMID:2553775

  17. High stability amplifier

    NASA Technical Reports Server (NTRS)

    Adams, W. A.; Reinhardt, V. S. (inventors)

    1983-01-01

    An electrical RF signal amplifier for providing high temperature stability and RF isolation and comprised of an integrated circuit voltage regulator, a single transistor, and an integrated circuit operational amplifier mounted on a circuit board such that passive circuit elements are located on side of the circuit board while the active circuit elements are located on the other side is described. The active circuit elements are embedded in a common heat sink so that a common temperature reference is provided for changes in ambient temperature. The single transistor and operational amplifier are connected together to form a feedback amplifier powered from the voltage regulator with transistor implementing primarily the desired signal gain while the operational amplifier implements signal isolation. Further RF isolation is provided by the voltage regulator which inhibits cross-talk from other like amplifiers powered from a common power supply. Input and output terminals consisting of coaxial connectors are located on the sides of a housing in which all the circuit components and heat sink are located.

  18. Luminescence of charge-sensitive oxygen centers in high-temperature superconductors - The effect of superconducting transition

    Microsoft Academic Search

    I. Ia. Fugol; V. N. Samovarov; Iu. I. Rybalko; V. M. Zhuravlev

    1990-01-01

    Principal results are presented of cathodoluminescence spectra of YBaCu and LaBaCu ceramics, textured YBaCu films, as well as of a number of classical metals and dielectrics. Two characteristic spectral groups of wide bands and narrow lines are revealed in the high-Tc superconducting spectrum which are sensitive to the superconducting phase. The emission components are assigned to oxygen radiation centers both

  19. Novel sulfur-doped niobium pentoxide nanoparticles: fabrication, characterization, visible light sensitization and redox charge transfer study

    Microsoft Academic Search

    Mohammad Hossein Habibi; Reza Mokhtari

    Novel sulfur-modified niobium(V) oxide nanoparticles (SNON) that firstly exhibited good visible light sensitization were fabricated\\u000a by a modified sol–gel technique using a very stable sol containing niobium(V) chloride, oxalic acid, isopropanol as chelating\\u000a agent and thiourea as sulfur source. The resulting S-doped Nb2O5 nanomaterials were characterized by cyclic voltammetry (CV), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy\\u000a (EDAX), scanning electron microscope

  20. Charge-Transfer Complexation at Carminic Acid–CdS Interface and Its Impact on the Efficiency of Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Shahzad, Naila; Shah, Syed Mujtaba; Munir, Shamsa; Hana, Amina; Jabeen, Uzma; Nosheen, Erum; Habib, Banafsha; Khan, Arif Ullah; Hassan, Zubair; Siddiq, Muhammad; Hussain, Hazrat

    2015-04-01

    We report for the first time charge-transfer complex formation at the interface of carminic acid and cadmium sulfide (CdS) nanoparticles. The complex formation was confirmed by ultraviolet-visible (UV-vis) and fluorescence emission spectroscopy. Cadmium sulfide nanoparticles were synthesized by the wet chemical method and characterized by UV-vis spectroscopy, x-ray diffraction and transmission electron microscopy. Carminic acid, in different concentrations, was chemisorbed on the surface of CdS nanoparticles. Grafting of carminic acid on CdS was confirmed by Fourier transform infrared spectroscopy. Energy levels of the highest occupied molecular orbitals and lowest unoccupied molecular orbitals (LUMO) of both carminic acid and CdS nanoparticles matched well for the injection of electron from LUMO of carminic acid to the conduction band of cadmium sulfide. The photoactive nanohybrid material was used in dye-sensitized solar cells. The efficiency of carminic acid functionalized CdS nanoparticles was found to be double the value obtained for the reference device and remained constant over a certain concentration range owing to the complex formation at the interface. However, raising the concentration of carminic acid beyond 2.5 × 10-5 M resulted in a decrease in efficiency. This was ascribed to charge recombination due to the presence of ungrafted carminic acid molecules.

  1. Highly efficient ZnO/Au Schottky barrier dye-sensitized solar cells: Role of gold nanoparticles on the charge-transfer process

    PubMed Central

    Bora, Tanujjal; Kyaw, Htet H; Sarkar, Soumik; Pal, Samir K

    2011-01-01

    Summary Zinc oxide (ZnO) nanorods decorated with gold (Au) nanoparticles have been synthesized and used to fabricate dye-sensitized solar cells (DSSC). The picosecond-resolved, time-correlated single-photon-count (TCSPC) spectroscopy technique was used to explore the charge-transfer mechanism in the ZnO/Au-nanocomposite DSSC. Due to the formation of the Schottky barrier at the ZnO/Au interface and the higher optical absorptions of the ZnO/Au photoelectrodes arising from the surface plasmon absorption of the Au nanoparticles, enhanced power-conversion efficiency (PCE) of 6.49% for small-area (0.1 cm2) ZnO/Au-nanocomposite DSSC was achieved compared to the 5.34% efficiency of the bare ZnO nanorod DSSC. The TCSPC studies revealed similar dynamics for the charge transfer from dye molecules to ZnO both in the presence and absence of Au nanoparticles. A slower fluorescence decay associated with the electron recombination process, observed in the presence of Au nanoparticles, confirmed the blocking of the electron transfer from ZnO back to the dye or electrolyte by the Schottky barrier formed at the ZnO/Au interface. For large area DSSC (1 cm2), ~130% enhancement in PCE (from 0.50% to 1.16%) was achieved after incorporation of the Au nanoparticles into the ZnO nanorods. PMID:22043457

  2. Comparison of TiO? and ZnO solar cells sensitized with an indoline dye: time-resolved laser spectroscopy studies of partial charge separation processes.

    PubMed

    Sobu?, Jan; Burdzi?ski, Gotard; Karolczak, Jerzy; Idígoras, Jesús; Anta, Juan A; Zió?ek, Marcin

    2014-03-11

    Time-resolved laser spectroscopy techniques in the time range from femtoseconds to seconds were applied to investigate the charge separation processes in complete dye-sensitized solar cells (DSC) made with iodide/iodine liquid electrolyte and indoline dye D149 interacting with TiO2 or ZnO nanoparticles. The aim of the studies was to explain the differences in the photocurrents of the cells (3-4 times higher for TiO2 than for ZnO ones). Electrochemical impedance spectroscopy and nanosecond flash photolysis studies revealed that the better performance of TiO2 samples is not due to the charge collection and dye regeneration processes. Femtosecond transient absorption results indicated that after first 100 ps the number of photoinduced electrons in the semiconductor is 3 times higher for TiO2 than for ZnO solar cells. Picosecond emission studies showed that the lifetime of the D149 excited state is about 3 times longer for ZnO than for TiO2 samples. Therefore, the results indicate that lower performance of ZnO solar cells is likely due to slower electron injection. The studies show how to correlate the laser spectroscopy methodology with global parameters of the solar cells and should help in better understanding of the behavior of alternative materials for porous electrodes for DSC and related devices. PMID:24568536

  3. Self-amplified piezoelectric nanogenerator with enhanced output performance: The synergistic effect of micropatterned polymer film and interweaved silver nanowires

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Hua, Bo; You, Sujian; Bu, Chenghao; Yu, Xiaolei; Yu, Zhenhua; Cheng, Nian; Cai, Bo; Liu, Huiqin; Li, Shasha; Zhang, Lingling; Wang, Shengxiang; Liu, Kan; Zhang, Nangang; Liu, Wei; Guo, Shishang; Zhao, Xing-Zhong

    2015-04-01

    A piezoelectric nanogenerator with self-amplified output is prepared with a polydimethylsiloxane (PDMS)/silver nanowire (Ag NW)/poly(vinylidene fluoride-trifluoroethylene) sandwich structure. The Ag NWs facilitate the collection of induced charge generated by the piezoelectric film, and the micro-patterned PDMS films multiply the devices sensitivity under external compression. The nanogenerator exhibits good performance, with a peak open circuit voltage of 1.2 V, and a peak short circuit current of 82 nA. These findings highlight the potential of the nanogenerator in self-powered devices and wearable energy harvesters.

  4. 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.

  5. 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.

  6. 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.

  7. CMOS low-noise switched charge sensitive preamplifier for CdTe and CdZnTe X-ray detectors

    SciTech Connect

    Jakobson, C.G.; Nemirovsky, Y. [Technion-Israel Inst. of Tech., Haifa (Israel)] [Technion-Israel Inst. of Tech., Haifa (Israel)

    1997-02-01

    CdTe and CdZnTe X-ray detector arrays for imaging and spectroscopy provide low capacitance current sources with low leakage currents. The optimal shaping time for low-noise operation is relatively high in CMOS analog channels that provide the readout for these detectors. The shaper is centered at lower frequencies, and thus the l/f noise from the electronics is the main noise source that limits the resolution of the channel. The optimal dimensions of the input stage MOSFET are determined by this noise. In this paper a design criterion for the optimization of the resolution and the power consumption in a l/f noise dominated readout is introduced. A readout based on CMOS switched charge sensitive preamplifier without feedback resistor has been designed and fabricated in the CMOS 2-{mu} low-noise analog process provided by MOSIS. This design provides high sensitivity and the possibility to integrate a large number of channels with low power consumption. Measurements of the performance of a first prototype chip are presented.

  8. Multipass amplifiers of POLARIS

    NASA Astrophysics Data System (ADS)

    Keppler, S.; Wandt, C.; Hornung, M.; Bödefeld, R.; Kessler, A.; Sävert, A.; Hellwing, M.; Schorcht, F.; Hein, J.; Kaluza, M. C.

    2013-05-01

    Advanced high intensity laser matter interaction experiments always call for optimized laser performance. In order to further enhance the POLARIS laser system, operational at the University of Jena and the Helmholtz-Institute Jena, in particular its energy, bandwidth and focusability, new amplifier technologies have been developed and are reported here. Additionally, existing sections were considerably improved. A new multi-pass amplification stage, which is able to replace two currently used ones, was developed in close collaboration with the MPQ (Garching). The new basic elements of this amplifier are well homogenized pump modules and the application of a successive imaging principle. By operating the amplifier under vacuum conditions a top hat beam profile with an output energy of up to 1.5 J per pulse is foreseen. The already implemented POLARIS amplifier A4 was further improved by adapting an advanced method for the homogenization of the multi-spot composed pump profile. The new method comprises a computer-based evolutionary algorithm which optimizes the position of the different spots regarding its individual size, shape and intensity. The latter allowed a better homogenization of the POLARIS near field profile.

  9. Magnetodynamic Mode Ferrite Amplifier

    Microsoft Academic Search

    Roy W. Roberts; Bert A. Auld; Robert R. Schell

    1962-01-01

    A longitudinally pumped ferrite amplifier has been operated using two magnetodynamic modes for the signal and idler resonant circuits. This is in contrast to the more usual electromagnetic cavity-type resonance or the ferrite magnetostatic modes. These magnetodynamic modes result from the coupling of a cavity-type resonance with a magnetostatic resonance. The coupling or mixing is strongest when the two unperturbed

  10. Active-RC variable equalizers with minimum number of operational amplifiers

    Microsoft Academic Search

    H. Malvar

    1983-01-01

    This paper describes some new active equalizers that are based on the Bode principle, but using shaping transfer functions instead of shaping immittances. It is shown that bump equalizers may be realized by circuits containing only one operational amplifier and only one variable element, with sensitivities somewhat higher than previous two-OA approaches. A low-sensitivity configuration using two operational amplifiers (OA's)

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

    DOEpatents

    Britton, Jr., Charles L. (Alcoa, TN); Wintenberg, Alan L. (Knoxville, TN)

    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.

  12. 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.

  13. Analysis of SSB Power Amplifiers

    Microsoft Academic Search

    FRED ASSADOURIAN

    1959-01-01

    It is well known that one of the critical items in a single sideband (SSB) transmitter is the power amplifier with which are associated the basic problems of distortion, output power and plate dissipation. Tubes are available which may be used either as quasi-linear RF amplifiers operated class AB or B or as gridmodulated amplifiers operated class C. In the

  14. The properties of amplified spontaneous emission noise in saturated fiber Raman amplifiers operating with CW signals

    E-print Network

    Eisenstein, Gadi

    The properties of amplified spontaneous emission noise in saturated fiber Raman amplifiers emission (ASE) noise in forward and backward pumped saturated Raman amplifiers operating with CW signals: Fiber Raman amplifier; Amplified spontaneous emission noise; Saturation 1. Introduction The noise

  15. The PreAmplifier ShAper for the ALICE TPC-Detector

    E-print Network

    Soltveit, H K; Braun-Munzinger, P; Musa, L; Gustafsson, H A; Bonnes, U; Oeschler, H; Osterman, L; Lang, S

    2012-01-01

    In this paper the PreAmplifier ShAper (PASA) for the Time Projection Chamber (TPC) of the ALICE experiment at LHC is presented. The ALICE TPC PASA is an ASIC that integrates 16 identical channels, each consisting of Charge Sensitive Amplifiers (CSA) followed by a Pole-Zero network, self-adaptive bias network, two second-order bridged-T filters, two non-inverting level shifters and a start-up circuit. The circuit is optimized for a detector capacitance of 18-25 pF. For an input capacitance of 25 pF, the PASA features a conversion gain of 12.74 mV/fC, a peaking time of 160 ns, a FWHM of 190 ns, a power consumption of 11.65 mW/ch and an equivalent noise charge of 244e + 17e/pF. The circuit recovers smoothly to the baseline in about 600 ns. An integral non-linearity of 0.19% with an output swing of about 2.1 V is also achieved. The total area of the chip is 18 mm$^2$ and is implemented in AMS's C35B3C1 0.35 micron CMOS technology. Detailed characterization test were performed on about 48000 PASA circuits before m...

  16. 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.

  17. Monolithic dye laser amplifier

    DOEpatents

    Kuklo, Thomas C. (Ripon, CA)

    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.

  18. 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.

  19. Invited review article: The Josephson bifurcation amplifier.

    PubMed

    Vijay, R; Devoret, M H; Siddiqi, I

    2009-11-01

    We review the theory, fabrication, and implementation of the Josephson bifurcation amplifier (JBA). At the core of the JBA is a nonlinear oscillator based on a reactively shunted Josephson junction. A weak input signal to the amplifier couples to the junction critical current I(0) and results in a dispersive shift in the resonator plasma frequency omega(p). This shift is enhanced by biasing the junction with a sufficiently strong microwave current I(rf) to access the nonlinear regime where omega(p) varies with I(rf). For a drive frequency omega(d) such that Omega=2Q(1-omega(d)/omega(p))>3, the oscillator enters the bistable regime where two nondissipative dynamical states O(L) and O(H), which differ in amplitude and phase, can exist. The sharp I(0) dependent transition from O(L) to O(H) forms the basis for a sensitive digital threshold amplifier. In the vicinity of the bistable regime (Omega<3), analog amplification of continuous signals is also possible. We present experimental data characterizing amplifier performance and discuss two specific applications--the readout of superconducting qubits (digital mode) and dispersive microwave magnetometry (analog mode). PMID:19947710

  20. High-speed high-voltage amplifier

    NASA Astrophysics Data System (ADS)

    Dyachko, A. N.; Ilyushenko, V. N.; Tuyev, V. I.

    1986-02-01

    A high speed amplifier of high voltage pulse signals coming from remote sources over long transmission lines is now available, specifically designed for increasing the sensitivity of 6 LOR-02 oscillographs. It includes a line attenuation compensator, besides the amplifier stage with a main output and an output for oscillograph synchronization. Each component can be used independently for any particular other application. The amplifier delivers negative voltage pulses of 300 V or higher amplitidue and 200 ns duration at a repetition rate of 10 kHz or higher to a 75 ohm load, with rise and fall times not exceeding 3 ns and with the pulse top flat within 10%. Its gain is 66 dB with manual regulation over a 40 dB range, its dynamic range is 40 dB at the input, and its amplitude characteristic is linear within 15% over the 30 to 300 V range. The amplifier stage uses a 60 V power supply and draws 0.9 A, the attenuation compensator uses a 15 V power supply and draws 0.15 A.

  1. Sensitive gas sensor embedded in a vertical polymer space-charge-limited Hsiao-Wen Zan, Chang-Hung Li, Chih-Kuan Yu, and Hsin-Fei Meng

    E-print Network

    detection limit to ammonia, the sensor can be used for non-invasive breath monitor in pointSensitive gas sensor embedded in a vertical polymer space-charge-limited transistor Hsiao-Wen Zan-domain correction of sensor dynamic error for step response Rev. Sci. Instrum. 83, 115002 (2012) Application of in

  2. Behavior of microfluidic amplifiers

    Microsoft Academic Search

    Rogério Furlan; Jay N. Zemel

    1995-01-01

    Two types of microfluidic amplifiers (wall-attachment and jet-deflection) have been implemented in silicon using standard micromachining methods and anodic sealing with a glass cap. The devices have areas of approximately 1 mm×0.5 mm and the complete structures with interconnection channels have areas of 12 or 18 mm×6 mm. Flow control and flow gain are demonstrated with supply pressures ranging up

  3. Saturated Operational Amplifier

    NSDL National Science Digital Library

    This animated gif illustrates the changing voltages when an operational amplifier (op-amp) becomes saturated. This animation would be useful for visually respresenting Finley's law. Voltages and parts of the circuit of this 3-D animated gif are highlighted with different colors. Current is displayed by green arrows indicating directional flow. The animation requires a Web browser or other video player software capable of displaying gif animations.Other 3-D Circuit Animations can be seen here.

  4. 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

  5. The influence of electron injection and charge recombination kinetics on the performance of porphyrin-sensitized solar cells: effects of the 4-tert-butylpyridine additive.

    PubMed

    Chang, Yu-Cheng; Wu, Hui-Ping; Reddy, Nagannagari Masi; Lee, Hsuan-Wei; Lu, Hsueh-Pei; Yeh, Chen-Yu; Diau, Eric Wei-Guang

    2013-04-01

    The effects of the 4-tert-butylpyridine (TBP) additive in the electrolyte on photovoltaic performance of two push-pull porphyrin sensitizers (YD12 and YD12CN) were examined. Addition of TBP significantly increased the open-circuit voltage (VOC) for YD12 (from 550 to 729 mV) but it was to a lesser extent for YD12CN (from 544 to 636 mV); adding TBP also had the effect of reducing the short-circuit current density (JSC) slightly for YD12 (from 17.65 to 17.19 mA cm(-2)) but it led to a significant reduction for YD12CN (from 16.45 to 9.78 mA cm(-2)). The resulting power conversion efficiencies of the YD12 devices increase from 6.2% to 8.5% whereas those of the YD12CN devices decrease from 5.8% to 4.5%. Based on measurements of temporally resolved photoelectric transients of the devices and femtosecond fluorescence decays of thin-film samples, the poor performance of the YD12CN device in the presence of TBP can be understood as being due to the enhanced charge recombination, decreased electron injection, and a lesser extent of inhibition of the intermolecular energy transfer. PMID:23423579

  6. 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

  7. Numerical Simulation of a Gridded Inductive Output Amplifier

    Microsoft Academic Search

    IOA MODEL

    A set of codes for the numerical simulation of a gridded Inductive Output Amplifier has been developed in close collaboration between BINP and Philips RHW. The following problems are investigated: nonstationary gridded gun simulation, self-consistent solution for beam-cavity interaction and passband calculations. The Finite Element Method is used for the field calculation in the electron gun. Space charge forces are

  8. 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.

  9. New low-noise output amplifier for high-definition CCD image sensor

    Microsoft Academic Search

    Nobuhiko Mutoh; Michihiro Morimoto; Miyo Nishimura; Nobukazu Teranishi; Eiji Oda

    1991-01-01

    A new low-noise charge-coupled-device (CCD) output amplifier, the RJG detector, has been developed. The RJG detector incorporates a JFET which has an electrically floating ring-junction gate (RJG). The operating principle of the amplifier is that signal charges, transferred from the CCD into the RJG, directly modulate the drain current in the detection JFET. The performance of the detector was evaluated

  10. Terahertz generation in optical amplifiers

    NASA Astrophysics Data System (ADS)

    Donkor, Eric

    2010-04-01

    We describe a fiber-optics based system for the generation of optical frequency comb using amplified spontaneous emissions from a semiconductor optical amplifier as signal source. The continuous wave spectrum from the semiconductor optical amplifier range from 1480nm to 1680nm. A Solc-Sagnac birefringent interferometer filtered the continuous wave into a comb of descrete spectral lines with line spacing of 600GHz, producing comb signals than span 182 to 230 terahertz.

  11. The cross-coupled amplifier 

    E-print Network

    Robinson, George Clyde

    1951-01-01

    . . . . . . . . ~ ~ ~ ~ 51 Bibliography Appendix ~ ~ ~ ~ ~ 54 THE CROSS COUPLED AMPLIFIER IHTRODUCTION In recent years electronic devices have found an increasing number of applications in many fields. Eost electronic devices make use of a vacuum-tube amplifier... as to be of practically no use to the designer. However, a few pertinent obser- vations regarding frequency response have been made. Reference to the schematic diagram of the cross- coupled amplifier reveals that the imput tubes Vl and V4 are connected as cathode...

  12. 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.

  13. An integrated CMOS dual lock-in amplifier for optoelectronic antigens detection

    NASA Astrophysics Data System (ADS)

    Hong, Nam-Pyo; Kim, Do-Gyun; Jung, In-Il; Son, Ho-Hyun; Chung, Tae-Kyung; Choi, Young-ki; Choi, Young-Wan

    2010-02-01

    We have designed dual lock-in amplifier (LIA) circuits in 0.18 ?m CMOS technology for antibody-antigens (IgG) detection using optoelectronics. The purpose of this work is to develop a lock-in amplifier integrated circuit (IC) using the dual phase scheme that detect the phase difference between the input signal and the reference signal although a phase shifter is absent. Our LIA consist of high gain amplifier, signal amplifier, and phase sensitive detection. Amplifier structure is based on two-stage differential operational amplifier (op-amp) with RC Miller compensation technique. By using the RC Miller compensation technique, we obtain 60° the phase margin of the op-amp. Here, the resistor works for increasing the unit gain bandwidth and the capacitor works for increasing the phase margin. The lock-in amplifier consume 8.6 mA from a 1.8 V supply.

  14. Reflex ring laser amplifier system

    DOEpatents

    Summers, Mark A. (Livermore, CA)

    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.

  15. Annealing behavior of radiation damage in JFET-input operational amplifiers

    NASA Astrophysics Data System (ADS)

    Yuzhan, Zheng; Wu, Lu; Diyuan, Ren; Yiyuan, Wang; Qi, Guo; Xuefeng, Yu

    2009-05-01

    The elevated and room temperature annealing behavior of radiation damage in JFET-input operational amplifiers (op-amps) were investigated. High- and low-dose-rate irradiation results show that one of the JFET-input op-amps studied in this paper exhibits enhanced low-dose-rate sensitivity and the other shows time-dependent effect. The offset voltage of both op-amps increases during long-term annealing at room temperature. However, the offset voltage decreases at elevated temperature. The dramatic difference in annealing behavior at room and elevated temperatures indicates the migration behavior of radiation-induced species at elevated and room temperatures. This provides useful information to understand the degradation and annealing mechanisms in JFET-input op-amps under total ionizing radiation. Moreover, the annealing of oxide trapped charges should be taken into consideration, when using elevated temperature methods to evaluate low-dose-rate damage.

  16. Properties of fiber Raman amplifiers and their applicability to digital optical communication systems

    Microsoft Academic Search

    Yasuhiro Aoki

    1988-01-01

    Bit error rate performances of fiber Raman amplifiers both as booster amplifiers and as detection preamplifiers are studied in intensity modulation\\/direct detection optical communication systems. It is theoretically shown that, in the booster amplifier application, receiver sensitivity degradation due to amplification can be made less than 0.2 dB for signal-to-noise power ratio larger than 20 dB, and thus an allowable

  17. 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

  18. Measuring momentum for charged particle tomography

    DOEpatents

    Morris, Christopher (Los Alamos, NM); Fraser, Andrew Mcleod (Los Alamos, NM); Schultz, Larry Joe (Los Alamos, NM); Borozdin, Konstantin N. (Los Alamos, NM); Klimenko, Alexei Vasilievich (Maynard, MA); Sossong, Michael James (Los Alamos, NM); Blanpied, Gary (Lexington, SC)

    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.

  19. Microstrip SQUID amplifiers for quantum information science

    NASA Astrophysics Data System (ADS)

    Defeo, M. P.; Plourde, B. L. T.

    2012-02-01

    Recent progress in SQUID amplifiers suggests that these devices might approach quantum-limited sensitivity in the microwave range, thus making them a viable option for measurement of superconducting quantum systems. In the microstrip SQUID amplifier configuration, gains of around 20dB are possible at frequencies of several hundred MHz, and the gain is limited by the maximum voltage modulation available from the SQUID. One route for increasing the voltage modulation involves using larger resistive shunts, however maintaining non-hysteretic device operation requires smaller junction capacitances than is possible with conventional photolithographically patterned junctions. Operating at higher frequencies requires a shorter input coil which reduces mutual inductance between the coil and washer and therefore gain. We have fabricated microstrip SQUID amplifiers using submicron Al-AlOx-Al junctions and large shunts. The input coil and SQUID washer are optimized for producing high gain at frequencies in the gigahertz range. Recent measurements of gain and noise temperature will be discussed as well as demonstrations of these devices as a first stage of amplification for a superconducting system

  20. Digital linearizer for RF amplifiers

    Microsoft Academic Search

    Sante Andreoli; Howard G. McClure; Paolo Banelli; Saverio Cacopardi

    1997-01-01

    Broadcast technology is at the beginning of a new era. It is characterized by the intensive use of the most advanced digital modulation formats (8VSB, QAM, OFDM) in combination with high power RF amplifiers. To date the linearity required for these digital formats has only been accomplished in cumbersome low efficiency class A amplifier or even more cumbersome feed-forward systems.

  1. Broadband fiber optical parametric amplifiers

    Microsoft Academic Search

    M. E. Marhic; N. Kagi; T.-K. Chiang; L. G. Kazovsky

    1996-01-01

    The bandwidth of a single-pump fiber optical parametric amplifier is governed by the even orders of f iber dispersion at the pump wavelength. The amplifier can exhibit gain over a wide wavelength range when operated near the fiber's zero-dispersion wavelength. It can also be used for broadband wavelength conversion, with gain. We have experimentally obtained gain of 10 - 18

  2. Brightness Amplifiers In Optical Systems

    NASA Astrophysics Data System (ADS)

    Zemskov, Konstantin I.; Kazarjan, Mishik A.; Petrash, Gueorgii G.

    1989-06-01

    Brief review of the last results on laser brightness amplifiers for different optical systems is given. Nonlinear properties of these systems and some new effects connected with the saturation of active medium of amplifiers are discussed. Some possible applica-tions (processing of microobjects, projection on large screen, TV-projection ...) are described.

  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. Effects of Iodine Content in the Electrolyte on the Charge Transfer and Power Conversion Efficiency of Dye-Sensitized Solar Cells under

    E-print Network

    Cao, Guozhong

    of Dye-Sensitized Solar Cells under Low Light Intensities Jo-Lin Lan, Tzu-Chien Wei,*, Shien-Ping Feng of dye-sensitized solar cells under lower light intensities. By analyzing the current-voltage behavior results in an exclusive application for indoor use. 1. INTRODUCTION Dye-sensitized solar cell (DSSC) has

  5. 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.

  6. Rayleigh scattering limitations in distributed Raman pre-amplifiers

    Microsoft Academic Search

    P. B. Hansen; L. Eskildsen; J. Stentz; T. A. Strasser; J. Judkins; J. J. Demarco; R. Pedrazzani; D. J. DiGiovanni

    1998-01-01

    The properties and fiber dependence of distributed Raman pre-amplifiers and, in particular, the effects of Rayleigh backscattering, which limits the sensitivity improvements that can be realized, is discussed. Bit-error-rate (BER) measurements show improvements In the effective receiver sensitivity of 6.2 and 7.0 dB for dispersion shifted fiber (DSF) and silica-core fiber (SCF), respectively. Theoretical predictions of the effective noise figure

  7. Glucose-sensitive ion-sensitive field-effect transistor-based biosensor with additional positively charged membrane. Dynamic range extension and reduction of buffer concentration influence on the sensor response

    Microsoft Academic Search

    Vjacheslav Volotovsky; Alexey P. Soldatkin; Alexander A. Shul'ga; Victor K. Rossokhaty; Vitaliy I. Strikha; Anna V. El'skaya

    1996-01-01

    Glucose-sensitive sensors based on ion-sensitive field-effect transistors were prepared by cross-linking a mixture of glucose oxidase and bovine serum albumin in saturated glutaraldehyde vapour on the sensitive area of the transducer. After this procedure, 4-vinylpyridine-styrene copolymer membranes were deposited on top of the sensors by drop-coating of 0.5% polymer solution in ethanol. The use of this additional membrane resulted in

  8. 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)

  9. Spontaneous separation of charged grains.

    PubMed

    Mehrotra, Amit; Muzzio, Fernando J; Shinbrot, Troy

    2007-08-01

    In 1867, Lord Kelvin described an experiment in which two streams of water droplets were connected so that each stream amplified the charge on the second stream [W. Thomson, Proc. R. Soc. London 16, 67 (1867)]. We present here a complementary effect in flowing grains that spontaneously separates similar and well-mixed grains into two charged streams of demixed grains. This effect has important consequences for industrial and natural processes. PMID:17930794

  10. Spontaneous Separation of Charged Grains

    NASA Astrophysics Data System (ADS)

    Mehrotra, Amit; Muzzio, Fernando J.; Shinbrot, Troy

    2007-08-01

    In 1867, Lord Kelvin described an experiment in which two streams of water droplets were connected so that each stream amplified the charge on the second stream [W. Thomson, Proc. R. Soc. LondonPRSLAZ0370-1662 16, 67 (1867).10.1098/rspl.1867.0019]. We present here a complementary effect in flowing grains that spontaneously separates similar and well-mixed grains into two charged streams of demixed grains. This effect has important consequences for industrial and natural processes.

  11. 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.

  12. The Resistance-Coupled Amplifier

    Microsoft Academic Search

    Laurence G. Cowles

    1945-01-01

    The routine problems of resistance-coupled amplifier design have been simplified and reduced to a set of graphs and convenient conversion charts. In the first section it is shown that the coupling circuit (Figure 1) can be replaced by a pair of equivalent resistance-capacitance circuits (Figure 3) so that it is easy to calculate an amplifier's phase and amplitude-frequency characteristics. The

  13. Parametric amplifier with thermoelectric refrigeration

    Microsoft Academic Search

    M. Uenohara; R. Wolfe

    1961-01-01

    The noise figure of a variable-capacitance parametric amplifier can be greatly improved by refrigerating the diode. A thermoelectric refrigerator can be used for this purpose without losing the advantage of system simplicity. A two-stage thermoelectric refrigerator has been built into a 6-Gc parametric amplifier. With no load this refrigerator has produced a temperature difference of 101°C below room temperature. In

  14. Amplified Dispersive Optical Tomography

    E-print Network

    Goda, Keisuke; Jalali, Bahram

    2008-01-01

    Optical coherence tomography (OCT) has proven to be a powerful technique for studying tissue morphology in ophthalmology, cardiology, and endomicroscopy. Its performance is limited by the fundamental trade-off between the imaging sensitivity and acquisition speed -- a predicament common in virtually all imaging systems. In this paper, we circumvent this limit by using distributed Raman post-amplification of the reflection from the sample. We combine the amplification with simultaneously performed dispersive Fourier transformation, a process that maps the optical spectrum into an easily measured time-domain waveform. The Raman amplification enables measurement of weak signals which are otherwise buried in noise. It extends the depth range without sacrificing the acquisition speed or causing damage to the sample. As proof of concept, single-shot imaging with 15 dB improvement in sensitivity at an axial scan rate of 36.6 MHz is demonstrated.

  15. LAB 4: OPERATIONAL AMPLIFIER CIRCUITS Introduction

    E-print Network

    Kozick, Richard J.

    . Figure 2 Inverting amplifier circuit (taken from [1]). 1. Derive the input-output relation: vo = f(vs,Rs,Rf = 1 V and Rg = 1 k. Design a noninverting amplifier (choose values of Rs and Rf) with an outputELEC 225 Fall 2011 1 LAB 4: OPERATIONAL AMPLIFIER CIRCUITS Introduction Operational amplifiers (OAs

  16. LAB 4: OPERATIONAL AMPLIFIER CIRCUITS Introduction

    E-print Network

    Kozick, Richard J.

    . Figure 2 Inverting amplifier circuit (taken from [1]). 1. Derive the input-output relation: vo = f(vs,Rs,Rf = 1 V and Rg = 1 k. Design a noninverting amplifier (choose values of Rs and Rf) with an outputELEC 225 Fall 2012 1 LAB 4: OPERATIONAL AMPLIFIER CIRCUITS Introduction Operational amplifiers (OAs

  17. Performance characteristics of an MSDC IOT amplifier

    Microsoft Academic Search

    E. McCune; C. Yates; Yanxia Li

    2000-01-01

    CPI EIMAC has provided inductive output tube (IOT) amplifier systems for the television broadcast market since 1988. The key performance advantage IOT amplifiers achieve over other high power UHF amplifier technologies are superior DC to RF power conversion efficiency. Efforts continue to further improve the power conversion efficiency of IOT amplifiers by employing multi-staged depressed collector (MSDC) technology. EIMAC has

  18. 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.

  19. Development of position sensitive radiation detectors using gas electron multipliers.

    PubMed

    Park, Seongtae; Hahn, Chang Hie

    2009-01-01

    Gas electron multipliers (GEM) were introduced to develop a radiation detector which is applicable to medical imaging or luggage inspection systems at the airport or harbor. Two GEM foils were used in the amplifier, and an Ar/CO(2) mixed gas was inserted into the chamber at a mixing ratio of Ar:CO(2)=80:20. A two-dimensional X-ray image was taken with a 64-channel GEM detector from an Fe-55 radiation source. We also constructed a 256-channel GEM detector in which 4 charge sensitive preamplifiers were used in a daisy chain. With linear array type readout electrodes, we were able to realize a position sensitive radiation detector. PMID:19282195

  20. The PreAmplifier ShAper for the ALICE TPC-Detector

    E-print Network

    H. K. Soltveit; J. Stachel; P. Braun-Munzinger; L. Musa; H. A. Gustafsson; U. Bonnes; H. Oeschler; L. Osterman; S. Lang

    2012-03-15

    In this paper the PreAmplifier ShAper (PASA) for the Time Projection Chamber (TPC) of the ALICE experiment at LHC is presented. The ALICE TPC PASA is an ASIC that integrates 16 identical channels, each consisting of Charge Sensitive Amplifiers (CSA) followed by a Pole-Zero network, self-adaptive bias network, two second-order bridged-T filters, two non-inverting level shifters and a start-up circuit. The circuit is optimized for a detector capacitance of 18-25 pF. For an input capacitance of 25 pF, the PASA features a conversion gain of 12.74 mV/fC, a peaking time of 160 ns, a FWHM of 190 ns, a power consumption of 11.65 mW/ch and an equivalent noise charge of 244e + 17e/pF. The circuit recovers smoothly to the baseline in about 600 ns. An integral non-linearity of 0.19% with an output swing of about 2.1 V is also achieved. The total area of the chip is 18 mm$^2$ and is implemented in AMS's C35B3C1 0.35 micron CMOS technology. Detailed characterization test were performed on about 48000 PASA circuits before mounting them on the ALICE TPC front-end cards. After more than two years of operation of the ALICE TPC with p-p and Pb-Pb collisions, the PASA has demonstrated to fulfill all requirements.

  1. The PreAmplifier ShAper for the ALICE TPC detector

    NASA Astrophysics Data System (ADS)

    Soltveit, H. K.; Stachel, J.; Braun-Munzinger, P.; Musa, L.; Gustafsson, H. A.; Bonnes, U.; Oeschler, H.; Osterman, L.; Lang, S.; ALICE TPC Collaboration

    2012-06-01

    In this paper the PreAmplifier ShAper (PASA) for the Time Projection Chamber (TPC) of the ALICE experiment at LHC is presented. The ALICE TPC PASA is an ASIC that integrates 16 identical channels, each consisting of Charge Sensitive Amplifiers (CSA) followed by a Pole-Zero network, self-adaptive bias network, two second-order bridged-T filters, two non-inverting level shifters and a start-up circuit. The circuit is optimized for a detector capacitance of 18-25 pF. For an input capacitance of 25 pF, the PASA features a conversion gain of 12.74 mV/fC, a peaking time of 160 ns, a FWHM of 190 ns, a power consumption of 11.65 mW/ch and an equivalent noise charge of 244e+17e/pF. The circuit recovers smoothly to the baseline in about 600 ns. An integral non-linearity of 0.19% with an output swing of about 2.1 V is also achieved. The total area of the chip is 18 mm2 and is implemented in AMS's C35B3C1 0.35 ?m CMOS technology. Detailed characterization tests were performed on about 48 000 PASA circuits before mounting them on the ALICE TPC front-end cards. After more than two years of operation of the ALICE TPC with p-p and Pb-Pb collisions, the PASA has demonstrated to fulfill all requirements.

  2. Nanomaterial-based amplified transduction of biomolecular interactions.

    PubMed

    Wang, Joseph

    2005-11-01

    This article reviews progress in the development of nanomaterials for amplified biosensing and discusses different nanomaterial-based bioamplification strategies. Signal amplification has attracted considerable attention for ultrasensitive detection of disease markers and biothreat agents. The emergence of nanotechnology is opening new horizons for highly sensitive bioaffinity and biocatalytic assays and for novel biosensor protocols that employ electronic, optical, or microgravimetric signal transduction. Nucleic acids and antibodies functionalized with metal or semiconductor nanoparticles have been employed as amplifying tags for the detection of DNA and proteins. The coupling of different nanomaterial-based amplification platforms and amplification processes dramatically enhances the intensity of the analytical signal and leads to ultrasensitive bioassays. The successful realization of the new nanoparticle-based signal amplification strategies requires proper attention to nonspecific adsorption issues. The implications of such nanoscale materials on amplified biodetection protocols and on the development of modern biosensors are discussed. PMID:17193390

  3. 500-Watt, 10-GHz Solid State Amplifier

    NASA Technical Reports Server (NTRS)

    Russell, K. J.; Pitzalis, O., Jr.

    1983-01-01

    X-band system amplifies low-duty-cycle pulses. Amplifier chain consists of driver-amplifier section using GaAs FET's with hybrid couplers, and power-amplifier section using IMPATT diodes with circulators for input/output coupling and for isolation between stages. Solid-state X-band amplifier package constitutes reliable, lightweight, compact, RF source. Used for many applications involving low-and variable-duty-cycle operation as well as fixed and high-duty-cycle operation.

  4. 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

  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. Fully differential cryogenic transistor amplifier

    NASA Astrophysics Data System (ADS)

    Beev, Nikolai; Kiviranta, Mikko

    2013-10-01

    We have constructed a dc-coupled differential amplifier capable of operating in the 4.2 K-300 K temperature range. The amplifier can be operated at high-bias setting, where it dissipates 5 mW, has noise temperature TN ? 0.7 K at RS ? 5 k? and >40 MHz bandwidth at 4.2 K bath temperature. The bias setting can be adjusted: at our lowest tested setting the amplifier dissipates <100 ?W, has noise temperature TN ? 2 K at RS ? 25 k? and >2 MHz bandwidth. The 1/f noise corner frequency is a few times 10 kHz. We foresee the amplifier to have an application in the readout of Superconducting Quantum Interference Devices (SQUIDs), Superconducting Tunnel Junction Detectors (STJs) and Transition Edge Sensors (TESes). We have verified the practical use of the amplifier by reading out a 4.2 K 480-SQUID array with 40 MHz bandwidth and <8 × 10-8 ?0/Hz1/2 flux noise.

  7. Data-dependant sense-amplifier flip-flop for low power applications

    Microsoft Academic Search

    Farshad Moradi; Charles Augustine; Ashish Goel; Georgeos Karakonstantis; Tuan Vu Cao; Dag Wisland; Hamid Mahmoodi; Kaushik Roy

    2010-01-01

    In this paper, we present a new sense amplifier based flip-flop that exploits input data activity, to achieve reduced power consumption. The internal nodes of the proposed flip-flop are charged\\/discharged only when the input data changes state. Simulations show that the power consumption of proposed flip-flop is reduced by 20% to 70% compared to standard sense-amplifier flip-flop. An FIR-filter based

  8. A large-signal analysis of the traveling-wave amplifier: Theory and general results

    Microsoft Academic Search

    J. E. Rowe

    1956-01-01

    Equations are derived describing the large-signal operation of the traveling-wave amplifier, including the effects of ac space charge and attenuation along the helical slow-wave structure. The equations constitute a system of nonlinear partial-differential-integral equations valid with reasonable approximations for all values of the parameters which are encountered in typical high-power traveling-wave amplifiers. The parameters which appear in the equations are

  9. Kinetics of photocurrent generation and an efficient charge separation of a dye-sensitized n-Cu2O/p-CuSCN junction photoelectrode in a solid-state photovoltaic cell

    NASA Astrophysics Data System (ADS)

    Fernando, C. A. N.; Kumara, N. T. R. N.; Gamage, T. N.

    2010-11-01

    A Cu/n-Cu2O/dye/p-CuSCN junction photoelectrode is fabricated to produce a solid-state dye-sensitized photovoltaic cell. Samples are characterized by XRD, SEM and surface resistivity measurements. Photocurrent generation is found due to light absorption of n-Cu2O thin film and dye sensitization between p-CuSCN and the dye. Kinetics of the photocurrent generation of the dye sensitization is studied solving the rate equations by the iteration method obtaining a relationship for the photocurrent quantum efficiency (?) depending on the surface concentration (Do) of the dye and the rate constants of the reactions with connection to the dye sensitization process. The solution obtained in the steady state by iteration is found to be of the form ? = ADo-BDo2 (A and B are constants related to the reaction rates of the photocurrent generation process and the concentration of the n-Cu2O film). The variation of the n-Cu2O concentration with photocurrent is presented. A photocurrent enhancement is observed for the Cu/n-Cu2O/dye/p-CuSCN photovoltaic cell compared to that of Cu/n-Cu2O, Cu/p-CuSCN/dye and Cu/n-Cu2O/p-CuSCN photovoltaic cells. Good rectification characteristics are observed for the Cu/n-Cu2O/p-CuSCN photoelectrode compared to that of Cu/n-Cu2O and Cu/p-CuSCN photoelectrodes. Photocurrent enhancement is found due to the efficient charge separation process at the n-p junction. Energy band structures of the n-p junction are proposed according to the onset potentials which are used to discuss the mechanism of the efficient charge separation suppressing the recombination process.

  10. 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

  11. 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

  12. Sensitivity of small-angle correlations of light charged particles to reaction mechanisms in the 16O+27Al reaction at 40 MeV\\/nucleon

    Microsoft Academic Search

    P. A. Deyoung; C. Dykstra; P. Gonthier; C. Mader; G. F. Peaslee; D. Peterson; R. Sedlar; S. Sundbeck; N. Shaw; G. Westfall; D. Craig; R. Lacey; T. Li; T. Reposeur; A. Vandermolen; J. S. Winfield; S. Yennello; A. Nadasen

    1997-01-01

    Small-angle p-p, p-d, d-alpha, and alpha-alpha correlation functions were measured following the reaction 16O+27Al at 40 MeV\\/nucleon 16O. These light charged particles (LCP's) were measured with a closely packed hexagonal array of CsI detectors, located at 35°, with a center to center opening angle of 2.35° for adjacent detectors. Coincident particles were simultaneously detected in the NSCL 4pi detector. This

  13. 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)

  14. 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 amplifiers in well optimized conventional lidar systems offers modest improvements, at best, (2) the practical advantages of optical amplifiers, especially fiber amplifiers, such as ease of alignment, compactness, efficiency, lightweight, etc., warrant further investigation for coherent lidar, (3) the possibility of more fully optical lidar systems should be explored, (4) advantages gained by use of coherent interference of optical fields at the level of one, or a few, signal quanta should be explored, (5) amplification without inversion, population trapping, and use of electromagnetic induced transparency warrant investigation in connection with coherent lidar, (6) these new findings are probably more applicable to earth related NASA work, although applications to deep space should not be excluded, and (7) our own work in the Ultrafast Laboratory at UAH along some of the above lines of investigation, may be useful.

  15. Optical systems with brightness amplifiers

    NASA Astrophysics Data System (ADS)

    Petrash, G. G.

    Papers included in this volume discuss principles involved in the operation of optical systems which use active media of pulsed metal-vapor lasers to amplify the brightness of images. Special attention is given to the problem of transformation of complex spatial intensity distributions in a light beam passing through a saturated active medium. A theoretical analysis is developed for the transformation of an image through a nonlinearly amplifying medium. Consideration is also given to a copper-vapor laser with a nonsteady resonator, and to applications of active optical systems in biology and medicine.

  16. Reactanceless synthesized impedance bandpass amplifier

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L. (inventor)

    1985-01-01

    An active R bandpass filter network is formed by four operational amplifier stages interconnected by discrete resistances. One pair of stages synthesize an equivalent input impedance of an inductance (L sub eq) in parallel with a discrete resistance (R sub o) while the second pair of stages synthesizes an equivalent input impedance of a capacitance (C sub eq) serially coupled to another discrete resistance (R sub i) coupled in parallel with the first two stages. The equivalent input impedances aggregately define a tuned resonant bandpass filter in the roll-off regions of the operational amplifiers.

  17. Amplified spontaneous Raman scattering and gain in fiber Raman amplifiers

    Microsoft Academic Search

    MARK L. DAKSS; Paul Melman

    1985-01-01

    The spectrum of amplified spontaneous Raman scattering and gain in a fiber Raman amplifer has been calculated analytically as a function of distance and pump power. The model used makes no assumptions on the magnitude of the gain and considers the pump nondepletion region. From the results, the on\\/off ratio has been calculated and is found to have a variation

  18. 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.

  19. Charge-transfer-induced suppression of galvanic replacement and synthesis of (Au-Ag)-Au double shell nanoparticles for highly uniform, robust and sensitive bioprobes

    SciTech Connect

    Dao Thi Ngoc Anh; Singh, Prerna; Shankar, Cheshta; Mott, Derrick; Maenosono, Shinya [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan)

    2011-08-15

    The synthesis of double shell (Au-Ag)-Au nanoparticles is accomplished through suppression of the galvanic replacement reaction caused by an electron transfer phenomenon. The resulting nanoparticles are monodisperse with a thin and uniform second Au shell. These particles are ultimately expected to lead to sensitive probes for biomolecular sensing and diagnostics.

  20. A CMOS Integrating Amplifier for the PHENIX Ring Imaging Cherenkov detector

    SciTech Connect

    Wintenberg, A.L.; Jones, J.P. Jr.; Young, G.R. [Oak Ridge National Lab., TN (United States); Moscone, C.G. [Tennessee Univ., Knoxville, TN (United States)

    1997-11-01

    A CMOS integrating amplifier has been developed for use in the PHENIX Ring Imaging Cherenkov (RICH) detector. The amplifier, consisting of a charge-integrating amplifier followed by a variable gain amplifier (VGA), is an element of a photon measurement system comprising a photomultiplier tube, a wideband, gain of 10 amplifier, the integrating amplifier, and an analog memory followed by an ADC and double correlated sampling implemented in software. The integrating amplifier is designed for a nominal full scale input of 160 pC with a gain of 20 mV/pC and a dynamic range of 1000:1. The VGA is used for equalizing gains prior to forming analog sums for trigger purposes. The gain of the VGA is variable over a 3:1 range using a 5 bits digital control, and the risetime is held to approximately 20 ns using switched compensation in the VGA. Details of the design and results from several prototype devices fabricated in 1.2 {micro}m Orbit CMOS are presented. A complete noise analysis of the integrating amplifier and the correlated sampling process is included as well as a comparison of calculated, simulated and measured results.

  1. Image relaying through saturated amplifiers

    Microsoft Academic Search

    Ernst E. Fill

    1984-01-01

    The transverse profile of a laser beam, determined by diffraction, is altered if the beam propagates through a medium with nonlinearity. Specifically, when a saturated amplifier is in the beam path of an image-relaying system, significant changes of the imaging properties occur. In this paper results of an experimental and theoretical study of this phenomenon are reported. It is shown

  2. An improved latching pulse design for dynamic sense amplifiers

    Microsoft Academic Search

    J. S. Yuan; J. J. Liou

    1990-01-01

    A generalized optimal latching pulse for dynamic sense-amplifier design has been derived. The model equations account for threshold-voltage imbalance bit-line capacitance imbalance, current-gain imbalance, gate capacitance and intra-bit-line capacitive coupling effect, channel-length modulation, source-body effect, and temperature sensitivity in a unified manner. Computer simulations of the analytical equations, including those effects, are presented. The analytical results provide physical insight into

  3. 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.

  4. High performance PbS Quantum Dot Sensitized Solar Cells exceeding 4% efficiency: the role of metal precursors in the electron injection and charge separation.

    PubMed

    González-Pedro, Victoria; Sima, Cornelia; Marzari, Gabriela; Boix, Pablo P; Giménez, Sixto; Shen, Qing; Dittrich, Thomas; Mora-Seró, Iván

    2013-09-01

    Here we report the preparation of high performance Quantum Dot Sensitized Solar Cells (QDSCs) based on PbS-CdS co-sensitized nanoporous TiO2 electrodes. QDs were directly grown on the TiO2 mesostructure by the Successive Ionic Layer Absorption and Reaction (SILAR) technique. This method is characterized by a fast deposition rate which involves random crystal growth and poor control of the defect states and lattice mismatch in the QDs limiting the quality of the electrodes for photovoltaic applications. In this work we demonstrate that the nature of the metallic precursor selected for SILAR has an active role in both the QD's deposition rate and the defect's distribution in the material, with important consequences for the final photovoltaic performance of the device. For this purpose, acetate and nitrate salts were selected as metallic precursors for the SILAR deposition and films with similar absorption properties and consequently with similar density of photogenerated carriers were studied. Under these conditions, ultrafast carrier dynamics and surface photovoltage spectroscopy reveal that the use of acetate precursors leads to higher injection efficiency and lower internal recombination due to contribution from defect states. This was corroborated in a complete cell configuration with films sensitized with acetate precursors, achieving unprecedented photocurrents of ~22 mA cm(-2) and high power conversion efficiency exceeding 4%, under full 1 sun illumination. PMID:23677043

  5. Blocking and desensitization in RF amplifiers

    Microsoft Academic Search

    Robert G. Meyer; Alvin K. Wong

    1995-01-01

    Blocking and desensitization in RF amplifiers is analyzed and related to second and third order intermodulation performance. Methods of predicting blocking behavior are described and used to improve the performance of an existing amplifier. Measurements are compared with theoretical predictions

  6. Fundamental noise limits in broadband Raman amplifiers

    Microsoft Academic Search

    C. R. S. Fludger; V. Handerek; R. J. Mears

    2001-01-01

    We show that broadband discrete Raman amplifiers based on silica-germania will have a noise figure significantly greater than the quantum limit. We also present temperature measurements on a broadband distributed Raman amplifier using asymmetrically-spaced pumps.

  7. Phase correlation in a Raman amplifier

    SciTech Connect

    Lombardi, G.G.; Injeyan, H.

    1986-10-01

    The effects of pump-beam temporal structure in a Raman amplifier were studied by using a frequency-doubled Nd:YAG laser. The experiment demonstrated that the Stokes wave becomes correlated with the pump as it is amplified. This leads to the result that, in general, the amplified Stokes wave is not coherent with the incident Stokes wave. The implications of this result for multiple-beam Raman amplifiers are discussed.

  8. A fluidic\\/pneumatic interface amplifier

    Microsoft Academic Search

    D. E. Limbert; T. M. Kegel

    1982-01-01

    The development of a low cost, reliable, linear pressure amplifier to interface Laminar Proportional Amplifiers (LPA) to pneumatic controllers is presented. The amplifier consists of an LPA input stage and an output stage consisting of a venturi in series with a bellows nozzle valve. The LPA output drives the bellows nozzle valve thereby altering the flowrate through the venturi. The

  9. A Fluidic\\/Pneumatic Interface Amplifier

    Microsoft Academic Search

    T. M. Kegel; D. E. Limbert

    1982-01-01

    The development of a low cost, reliable, linear pressure amplifier to interface Laminar Proportional Amplifiers (LPA) to pneumatic controllers is presented. The amplifier consists of an LPA input stage and an output stage consisting of a venturi in series with a bellows nozzle valve. The LPA output drives the bellows nozzle valve thereby altering the flowrate through the venturi. The

  10. 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.

  11. 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.

  12. Optimization of cascaded regenerative links based on phase sensitive amplifiers

    E-print Network

    Turitsyn, Sergei K.

    optimization of the transfer function and the signal alphabet. The model is general and can be applied to any regenerative system. © 2013 Optical Society of America OCIS codes: (060.2330) Fiber optics communications; (060.4370) Nonlinear optics, fibers; (190.4370) Nonlinear optics, fibers; (060.1660) Coherent communications; (000

  13. Radiation hardening techniques for rare-earth-based optical fibers and amplifiers

    NASA Astrophysics Data System (ADS)

    Girard, Sylvain; Vivona, Marilena; Mescia, Luciano; Laurent, Arnaud; Ouerdane, Youcef; Marcandella, Claude; Prudenzano, F.; Boukenter, Aziz; Robin, Thierry; Cadier, Benoît; Pinsard, Emmanuel; Cannas, Marco; Boscaino, Roberto

    2012-02-01

    Er/Yb doped fibers and amplifiers have been shown to be very radiation sensitive, limiting their integration in space. We present an approach including successive hardening techniques to enhance their radiation tolerance. The efficiency of our approach is demonstrated by comparing the radiation responses of optical amplifiers made with same lengths of different rare-earth doped fibers and exposed to gamma-rays. Previous studies indicated that such amplifiers suffered significant degradation for doses exceeding 10 krad. Applying our techniques significantly enhances the amplifier radiation resistance, resulting in a very limited degradation up to 50 krad. Our optimization techniques concern the fiber composition, some possible pre-treatments and the interest of simulation tools used to harden by design the amplifiers. We showed that adding cerium inside the fiber phosphosilicate-based core strongly decreases the fiber radiation sensitivity compared to the standard fiber. For both fibers, a pre-treatment with hydrogen permits to enhance again the fiber resistance. Furthermore, simulations tools can also be used to improve the tolerance of the fiber amplifier by helping identifying the best amplifier configuration for operation in the radiative environment.

  14. Stability Analysis of On-Chip MultiStage RF Power Amplifiers

    Microsoft Academic Search

    Martin Unterweissacher; Koen Mertens; Thomas Brandtner; Wolfgang Pribyl

    2007-01-01

    On-chip multi-stage wideband power amplifiers may show oscillations due to an unwanted feedback loop via the power distribution network. A fully differential CMOS amplifier with a bandwidth from 6 to 9 GHz that was expected to be sensitive to oscillations has been analyzed by utilizing a novel pre-layout method for estimating power grid parasitics including inductance effects. Sweeping the parameters

  15. Slow interfacial charge recombination in solid-state dye-sensitized solar cell using Al 2O 3-coated nanoporous TiO 2 films

    Microsoft Academic Search

    Xin-Tong Zhang; Hong-Wu Liu; Taketo Taguchi; Qing-Bo Meng; Osamu Sato; Akira Fujishima

    2004-01-01

    Al2O3-coated TiO2 porous films were used to fabricate solid-state dye-sensitized solar cells using CuI as hole conductor. Investigation with transient photovoltage measurements showed that the Al2O3 interlayer slowed down the interfacial recombination of electrons in TiO2 with holes in CuI by forming a potential barrier at the TiO2\\/CuI interface. As a consequence, the cell made from Al2O3-coated TiO2 film showed

  16. Particle-Charge Spectrometer

    NASA Technical Reports Server (NTRS)

    Fuerstenau, Stephen; Wilson, Gregory R.

    2008-01-01

    An instrument for rapidly measuring the electric charges and sizes (from approximately 1 to approximately 100 micrometers) of airborne particles is undergoing development. Conceived for monitoring atmospheric dust particles on Mars, instruments like this one could also be used on Earth to monitor natural and artificial aerosols in diverse indoor and outdoor settings for example, volcanic regions, clean rooms, powder-processing machinery, and spray-coating facilities. The instrument incorporates a commercially available, low-noise, ultrasensitive charge-sensing preamplifier circuit. The input terminal of this circuit--the gate of a field-effect transistor--is connected to a Faraday-cage cylindrical electrode. The charged particles of interest are suspended in air or other suitable gas that is made to flow along the axis of the cylindrical electrode without touching the electrode. The flow can be channeled and generated by any of several alternative means; in the prototype of this instrument, the gas is drawn along a glass capillary tube (see upper part of figure) coaxial with the electrode. The size of a particle affects its rate of acceleration in the flow and thus affects the timing and shape of the corresponding signal peak generated by the charge-sensing amplifier. The charge affects the magnitude (and thus also the shape) of the signal peak. Thus, the signal peak (see figure) conveys information on both the size and electric charge of a sensed particle. In experiments thus far, the instrument has been found to be capable of measuring individual aerosol particle charges of magnitude greater than 350 e (where e is the fundamental unit of electric charge) with a precision of +/- 150 e. The instrument can sample particles at a rate as high as several thousand per second.

  17. Decreasing the thresholds for electroporation by sensitizing cells with local cationic anesthetics and substances that decrease the surface negative electric charge.

    PubMed

    Grys, Maciej; Madeja, Zbigniew; Korohoda, W?odzimierz

    2014-03-01

    The recently described method of cell electroporation by flow of cell suspension through localized direct current electric fields (dcEFs) was applied to identify non-toxic substances that could sensitize cells to external electric fields. We found that local cationic anesthetics such as procaine, lidocaine and tetracaine greatly facilitated the electroporation of AT2 rat prostate carcinoma cells and human skin fibroblasts (HSF). This manifested as a 50% reduction in the strength of the electric field required to induce cell death by irreversible electroporation or to introduce fluorescent dyes such as calcein, carboxyfluorescein or Lucifer yellow into the cells. A similar decrease in the electric field thresholds for irreversible and reversible cell electroporation was observed when the cells were exposed to the electric field in the presence of the non-toxic cationic dyes 9-aminoacridine (9-AAA) or toluidine blue. Identifying non-toxic, reversibly acting cell sensitizers may facilitate cancer tissue ablation and help introduce therapeutic or diagnostic substances into the cells and tissues. PMID:24415057

  18. The spectacular human nose: an amplifier of individual quality?

    PubMed Central

    Mikalsen, ?se 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

  19. Log amplifier with pole-zero compensation

    DOEpatents

    Brookshier, William (Downers Grove, IL)

    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.

  20. High power gas laser amplifier

    SciTech Connect

    Leland, W.T.; Stratton, T.F.

    1981-04-28

    A high power output CO/sub 2/ gas laser amplifier is described that has 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.

  1. 64-channel ultrasound transducer amplifier

    Microsoft Academic Search

    James Morizio; S. Guhados; J. Castellucci; O. von Ramm

    2003-01-01

    In this paper we present a 64-channel ultrasound preamplifier device that is used to amplify and filter pulsed echo transducer signals sourced from a real time three dimensional (RT3DU) non-invasive ultrasound system. Schematics, simulation data, and layout for each of the broadband sub-circuit macros are described which include a high gain preamplifier, a linear output buffer, and bias circuits. This

  2. Transistor 70Mc IF amplifier

    Microsoft Academic Search

    V. Saari

    1958-01-01

    A 70-Mc IF amplifier using seven diffused-base germanium transistors is described. The insertion gain is 90 db, with bandwidth greater than 15 mc, flat to within ±0.3 db. The +12-dbm output is stabilized against change in input level or temperature by 35 db of AGC and the noise figure is 5 db. A digital computer was used as a tool

  3. High power gas laser amplifier

    DOEpatents

    Leland, Wallace T. (Los Alamos, NM); Stratton, Thomas F. (Los Alamos, NM)

    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.

  4. High power regenerative laser amplifier

    DOEpatents

    Miller, John L. (Livermore, CA); Hackel, Lloyd A. (Livermore, CA); Dane, Clifford B. (Dublin, CA); Zapata, Luis E. (Livermore, CA)

    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.

  5. High power regenerative laser amplifier

    SciTech Connect

    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.

  6. Influence of electrical potential distribution, charge transport, and recombination on the photopotential and photocurrent conversion efficiency of dye-sensitized nanocrystalline TiO{sub 2} solar cells: A study by electrical impedance and optical modulation techniques

    SciTech Connect

    Lagemaat, J. van de; Park, N.G.; Frank, A.J.

    2000-03-09

    The role of electrical potential, charge transport, and recombination in determining the photopotential and photocurrent conversion efficiency (IPCE) of dye-sensitized nanocrystalline solar cells was studied. Electrostatic arguments and electrical impedance spectroscopy (EIS) are used to obtain information on the electrical and electrochemical potential distribution in the cell. It is shown that on the macroscopic level, no significant electrical potential drop exists within the porous TiO{sub 2} when it contacts the electrolyte and that the electrical potential drop at the transparent conducting oxide substrate (TCO)/TiO{sub 2} interface occurs over a narrow region, one or two layers of TiO{sub 2}. Analyses of EIS and other data indicate that both the photopotential of the cell and the decrease of the electrical potential drop across the TCO/TiO{sub 2} interface are caused by the buildup of photoinjected electrons in the TiO{sub 2} film. The time constants for the recombination and collection of the photoinjected electrons are measured by EIS and intensity-modulated photocurrent spectroscopy (IMPS). As the applied bias is varied from short-circuit to open-circuit conditions at 1 sun light intensity, recombination becomes faster, the collection of electrons becomes slower, and the IPCE decreases. The decrease of IPCE correlates directly with the decline of the charge-collection efficiency {eta}{sub cc}, which is obtained from the time constants for the recombination and collection of the photoinjected electrons. Significantly, at open circuit, {eta}{sub cc} is only 45% of its short-circuit value, indicating that the dye-sensitized nanocrystalline TiO{sub 2} solar cell behaves as a nonideal photodiode.

  7. 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.

  8. 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.

  9. 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.

  10. Highly sensitive Hall sensor in CMOS technology

    Microsoft Academic Search

    H Blanchard; F De Montmollin; J Hubin; R. S Popovic

    2000-01-01

    We present a highly sensitive Hall device fabricated in a standard CMOS technology and combined with integrated flux concentrators acting as magnetic amplifiers. The active area of the Hall plate is in a buried n-well with a shape optimized by removing the parts less sensitive to the magnetic field. The effect of the shape of the concentrators is studied. This

  11. Ping-pong auto-zero amplifier with glitch reduction

    DOEpatents

    Larson, Mark R. (Maple Grove, MN)

    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.

  12. 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.

  13. Inverting Amplifier with Current Input

    NSDL National Science Digital Library

    This animated gif illustrates the changing voltages a conventional inverting amplifier when it receives input from a current source rather than a voltage source. Notice that the input resistor does not offer any impedance. Voltages and parts of the circuit of this 3-D animated gif are highlighted with different colors. Current is displayed by green arrows indicating directional flow. The animation requires a Web browser or other video player software capable of displaying gif animations.Other 3-D Circuit Animations can be seen here.

  14. A Charge-Based Low-Power High-SNR Capacitive Sensing Interface Circuit

    Microsoft Academic Search

    Sheng-Yu Peng; Muhammad S. Qureshi; Paul E. Hasler; Arindam Basu; F. Levent Degertekin

    2008-01-01

    This paper describes a low-power approach to capacitive sensing that achieves a high signal-to-noise ratio (SNR). The circuit is composed of a capacitive feedback charge amplifier and a charge adaptation circuit. Without the adaptation circuit, the charge amplifier only consumes 1 muW to achieve the audio band SNR of 69.34 dB. An adaptation scheme using Fowler-Nordheim tunneling and channel hot-electron

  15. Biosensing: Taking charge of biomolecules

    NASA Astrophysics Data System (ADS)

    Kinsella, Joseph M.; Ivanisevic, Albena

    2007-10-01

    The combination of two scanning probe microscopy techniques has led to a label-free method of detecting charged molecules at the nanoscale and offers a general approach to biosensing with improved resolution, sensitivity and speed.

  16. The high gain 1310nm Raman amplifier

    NASA Astrophysics Data System (ADS)

    Turkiewicz, Jaros?aw Piotr; Czy?ak, Pawe?

    2014-05-01

    Due to the growing demand for transmission capacity, it has become essential to utilize multiple wavelength domains in one transmission system. To take full advantage of parallel 1550/1310 nm transmission, efficient 1310 nm amplification techniques are needed, such as the 1310 nm Raman amplifier. In the paper, we present detailed studies regarding the design of the 1310 nm Raman amplifier. Based on numerical simulations, we propose an efficient 1310 nm Raman amplifier design, utilizing the 1240 nm quantum-dot pumping lasers. The designed Raman amplifier is built and characterized. The achieved gain in a QD-laser pumped 1310 nm Raman amplifier was 19.5 dB. The presented results open the way for enhanced utilization of the 1310 nm Raman amplifier in the opto-telecommunication systems.

  17. Integrated ytterbium-Raman fiber amplifier.

    PubMed

    Zhang, Lei; Jiang, Huawei; Cui, Shuzhen; Feng, Yan

    2014-04-01

    An integrated ytterbium-Raman fiber amplifier architecture is proposed for power scaling of a Raman fiber laser. It is an ytterbium (Yb) fiber amplifier seeded with a double or multiple wavelength laser and followed by a passive Raman fiber. The bluest wavelength light gets amplified in the Yb fiber and the power is transferred to redder wavelengths in the following Raman fiber. A proof of principle experiment demonstrates a 300 W all-fiber linearly polarized single mode amplifier at 1120 nm with an optical efficiency of 70%, limited only by available pump power. The amplifier consists of 4 m of Yb-doped fiber and 20 m of germanium-doped fiber, and seeded with a laser emitting at 1070 and 1120 nm. The power evolution of the 1070 and 1120 nm light inside the amplifier is investigated, both numerically and experimentally. The possibility of power scaling to over kilowatt levels is discussed. PMID:24686642

  18. 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.

  19. Fiber amplifiers for coherent space communication

    Microsoft Academic Search

    Etienne Rochat; René Dändliker; Karim Haroud; Reinhard H. Czichy; Ulrich Roth; D. Costantini; Reto Holzner

    2001-01-01

    We report on the application of double-clad doped fiber amplifiers for coherent space communication systems using a master oscillator power amplifier (MOPA) design at 1.06 ?m. The master oscillator is either a single-frequency Nd:YAG solid-state laser or a distributed-feedback fiber laser. The power amplifier is a diode-laser-pumped double-clad Nd doped fiber with polarization control, 20 dB gain, and about 1.3

  20. Raman amplifier with improved system performance

    Microsoft Academic Search

    A. J. Stentz; S. G. Grubb; J. R. Simpson; T. Strasser

    1996-01-01

    Summary form only given. We describe the predominant sources of noise for various amplifier configurations. In addition, we present the results of a successful 2.5 Gbit\\/s systems test of a two-stage Raman amplifier with net small signal gains of 29 dB and output powers exceeding + 15 dBm. Although Raman amplifiers do not suffer from increased noise figure due to

  1. A novel darlington amplifier optimized for wideband

    Microsoft Academic Search

    Oleg V. Stukach

    2008-01-01

    A new design topology and performance for the ultra wideband Darlington amplifier is described. The amplifier configuration consists of a common-emitter transistor pair with low-pass filter. The normalized gain characteristic for the amplifier provides 1.36 multiple expansion of frequency band without degradation of the dynamic range, at VSWR and matching of input-output retaining. Expression for the optimum transfer factor was

  2. A comparative study of state-of-the-art low-power CAM match-line sense amplifier designs

    Microsoft Academic Search

    Anh-Tuan Do; Xiaoliang Tan; Shoushun Chen; Zhi-Hui Kong; Kiat Seng Yeo

    2011-01-01

    Robust, high-performance and low-power match-line sense amplifier designs are urgently required to catch up with the new requirements of large-scale CAMs in nano-scale CMOS technologies. In this paper we evaluate the performance of four state-of-the-art match-line sense amplifier designs in terms of power, delay and robustness against temperature, supply voltage and process variations. Our results show that the pre-charge low

  3. 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.

  4. Electron beam emission from a diamond-amplifier cathode.

    PubMed

    Chang, Xiangyun; Wu, Qiong; Ben-Zvi, Ilan; Burrill, Andrew; Kewisch, Jorg; Rao, Triveni; Smedley, John; Wang, Erdong; Muller, Erik M; Busby, Richard; Dimitrov, Dimitre

    2010-10-15

    The diamond amplifier (DA) is a new device for generating high-current, high-brightness electron beams. Our transmission-mode tests show that, with single-crystal, high-purity diamonds, the peak current density is greater than 400??mA/mm², while its average density can be more than 100??mA/mm². The gain of the primary electrons easily exceeds 200, and is independent of their density within the practical range of DA applications. We observed the electron emission. The maximum emission gain measured was 40, and the bunch charge was 50??pC/0.5??mm². There was a 35% probability of the emission of an electron from the hydrogenated surface in our tests. We identified a mechanism of slow charging of the diamond due to thermal ionization of surface states that cancels the applied field within it. We also demonstrated that a hydrogenated diamond is extremely robust. PMID:21230979

  5. 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.

  6. A high sensitivity ultralow temperature RF conductance and noise measurement setup

    SciTech Connect

    Parmentier, F. D.; Mahe, A.; Denis, A.; Berroir, J.-M.; Glattli, D. C.; Placais, B.; Feve, G. [Laboratoire Pierre Aigrain, Ecole Normale Superieure, CNRS UMR 8551, Universite P. et M. Curie, Universite D. Diderot 24, rue Lhomond, 75231 Paris Cedex 05 (France)

    2011-01-15

    We report on the realization of a high sensitivity RF noise measurement scheme to study small current fluctuations of mesoscopic systems at milli-Kelvin temperatures. The setup relies on the combination of an interferometric amplification scheme and a quarter-wave impedance transformer, allowing the measurement of noise power spectral densities with gigahertz bandwidth up to five orders of magnitude below the amplifier noise floor. We simultaneously measure the high frequency conductance of the sample by derivating a portion of the signal to a microwave homodyne detection. We describe the principle of the setup, as well as its implementation and calibration. Finally, we show that our setup allows to fully characterize a subnanosecond on-demand single electron source. More generally, its sensitivity and bandwidth make it suitable for applications manipulating single charges at GHz frequencies.

  7. A high sensitivity ultralow temperature RF conductance and noise measurement setup.

    PubMed

    Parmentier, F D; Mahé, A; Denis, A; Berroir, J-M; Glattli, D C; Plaçais, B; Fève, G

    2011-01-01

    We report on the realization of a high sensitivity RF noise measurement scheme to study small current fluctuations of mesoscopic systems at milli-Kelvin temperatures. The setup relies on the combination of an interferometric amplification scheme and a quarter-wave impedance transformer, allowing the measurement of noise power spectral densities with gigahertz bandwidth up to five orders of magnitude below the amplifier noise floor. We simultaneously measure the high frequency conductance of the sample by derivating a portion of the signal to a microwave homodyne detection. We describe the principle of the setup, as well as its implementation and calibration. Finally, we show that our setup allows to fully characterize a subnanosecond on-demand single electron source. More generally, its sensitivity and bandwidth make it suitable for applications manipulating single charges at GHz frequencies. PMID:21280842

  8. 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

  9. Noise in buried channel charge-coupled devices

    Microsoft Academic Search

    R. W. Brodersen; S. P. Emmons

    1976-01-01

    A correlated double sampling technique was used to measure noise at the output of a buried channel charge-coupled device (BCCD) linear shift register. Four sources of noise - the electrical insertion of signal charge, the output amplifier, dark current, and bulk state trapping - were analyzed. The output circuit used in the measurements had a noise level equivalent to less

  10. 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.

  11. Wideband Envelope Elimination and Restoration Power Amplifier with High Efficiency Wideband Envelope Amplifier for WLAN

    E-print Network

    Asbeck, Peter M.

    is the product of the envelope amplifier efficiency and RF transistor drain efficiency, i.e: transistorWideband Envelope Elimination and Restoration Power Amplifier with High Efficiency Wideband Envelope Amplifier for WLAN 802.11g Applications Feipeng Wang, Donald Kimball, Jeremy Popp*, Annie Yang

  12. DESIGN OF DIGITAL STEREO AMPLIFIER FOR MOBILE IT DEVICE

    Microsoft Academic Search

    Young-Gyu Choi

    It is well known that digital amplifier is better than analog amplifier from the viewpoint of efficiency. Efficiency of analog amplifier is low and it has disadvantage that do not attach cooling fan by noise of inside. And also, external form size of analog amplifier can¡t but be big because of heat sink. Therefore, analog amplifier is not suitable to

  13. Take Charge!

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    Students come to understand static electricity by learning about the nature of electric charge, and different methods for charging objects. In a hands-on activity, students induce an electrical charge on various objects, and experiment with electrical repulsion and attraction.

  14. Hidden Amplifier for a Galvanometer

    NASA Astrophysics Data System (ADS)

    Weichman, Frank

    2003-10-01

    We often do demonstrations at local schools that require the use of a sensitive galvanometer. For example, we show that a thermocouple responds to warm fingers and will respond with opposite polarity to cool water. In years past we brought along a Pye galvanometer, which had adequate sensitivity for the purpose but which suffered from drift due to ambient temperature changes (cold car to warm classroom) and slow response time. There are of course many digital instruments available with adequate sensitivity, but for a classroom setting with 20 to 30 itchy children, an analogue device is preferable to a fluctuating digital output.

  15. 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.

  16. Free randomness can be amplified

    E-print Network

    Roger Colbeck; Renato Renner

    2013-06-18

    Are there fundamentally random processes in nature? Theoretical predictions, confirmed experimentally, such as the violation of Bell inequalities, point to an affirmative answer. However, these results are based on the assumption that measurement settings can be chosen freely at random, so assume the existence of perfectly free random processes from the outset. Here we consider a scenario in which this assumption is weakened and show that partially free random bits can be amplified to make arbitrarily free ones. More precisely, given a source of random bits whose correlation with other variables is below a certain threshold, we propose a procedure for generating fresh random bits that are virtually uncorrelated with all other variables. We also conjecture that such procedures exist for any non-trivial threshold. Our result is based solely on the no-signalling principle, which is necessary for the existence of free randomness.

  17. 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.

  18. Resonant isolator for maser amplifier

    NASA Technical Reports Server (NTRS)

    Clauss, R. C.; Quinn, R. B. (inventors)

    1983-01-01

    An isolator is described for use in a low noise maser amplifier, which provides low loss across a wide bandwidth and which can be constructed at moderate cost. The isolator includes a train of garnet or ferrite elements extending along the length of a microwave channel parallel to the slow wave structure, with the elements being of staggered height, so that the thin elements which are resonant to the microwaves are separated by much thicker elements. The thick garnet or ferrite elements reduce the magnetic flux passing through the thin elements to permit altering of the shape of the thin elements so as to facilitate their fabrication and to provide better isolation with reduced loss, by increasing the thickness of the thin elements and decreasing their length and width.

  19. 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

  20. CMOS Optoelectronic Lock-In Amplifier With Integrated Phototransistor Array.

    PubMed

    An Hu; Chodavarapu, Vamsy P

    2010-10-01

    We describe the design and development of an optoelectronic lock-in amplifier (LIA) for optical sensing and spectroscopy applications. The prototype amplifier is fabricated using Taiwan Semiconductor Manufacturing Co. complementary metal-oxide semiconductor 0.35-?m technology and uses a phototransistor array (total active area is 400 ?m × 640?m) to convert the incident optical signals into electrical currents. The photocurrents are then converted into voltage signals using a transimpedance amplifier for subsequent convenient signal processing by the LIA circuitry. The LIA is optimized to be operational at 20-kHz modulation frequency but is operational in the frequency range from 13 kHz to 25 kHz. The system is tested with a light-emitting diode (LED) as the light source. The noise and signal distortions are suppressed with filters and a phase-locked loop (PLL) implemented in the LIA. The output dc voltage of the LIA is proportional to the incident optical power. The minimum measured dynamic reserve and sensitivity are 1.31 dB and 34 mV/?W, respectively. The output versus input relationship has shown good linearity. The LIA consumes an average power of 12.79 mW with a 3.3-V dc power supply. PMID:23853373

  1. 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.

  2. Noise in IMPATT Diode Amplifiers and Oscillators

    Microsoft Academic Search

    HANS-JORG THALER; GERHARD ULRICH; GERHARD WEIDMANN

    1971-01-01

    The results of experimental and theoretical investigations of the noise characteristics of lMPATT diode amplifiers and oscillators are presented. The oscillator noise is shown to consist of three different contributions: modulation noise, selectively amplified primary noise, and conversion noise. The influence of the active device nonlinearity and load circuit parameters is discussed in detail. The experimental results are in good

  3. Phase Noise in RF and Microwave Amplifiers

    E-print Network

    Boudot, Rodolphe

    2010-01-01

    Understanding the amplifier phase noise is a critical issue in numerous fields of engineering and physics, like oscillators, frequency synthesis, telecommunications, radars, spectroscopy, in the emerging domain of microwave photonics, and in more exotic domains like radio astronomy, particle accelerators, etc. This article analyzes the two main types of phase noise in amplifiers, white and flicker. White phase noise results from adding white noise to the RF spectrum around the carrier. For a given amount of RF noise added, noise is proportional to the inverse of the carrier power. By contrast, the 1/f coefficient is a constant parameter of the amplifier, in a wide range of carrier power. This fact has amazing consequences on different amplifier topologies. Connecting m equal amplifiers in parallel, flicker is 1/m times that of one device. Cascading m equal amplifiers, flicker 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...

  4. Design of a 250 GHz gyrotron amplifier

    E-print Network

    Nanni, Emilio A. (Emilio Alessandro)

    2010-01-01

    A design is presented of a 250 GHz, 1 kW gyrotron traveling wave tube (gyro-TWT) amplifier with gain exceeding 50 dB. Calculations show that the amplifier will operate at 32 kV, 1 A with a saturated gain of 60 dB, an output ...

  5. The Transistor A New Semiconductor Amplifier

    Microsoft Academic Search

    J. A. Becker; Aiee; J. N. Shive

    1999-01-01

    This article describes the construction, characteristics, and behavior of the newly discovered device, the transistor. Used as a semiconductor amplifier, it works on an entirely different principle and is capable of performing the same tasks now done by the vacuum tube triode. “Transistor” is the name which has been given to the semiconductor amplifier triode recently developed at the Bell

  6. Push-pull audio amplifier theory

    Microsoft Academic Search

    M. Melehy

    1957-01-01

    Assuming nonlinear tube characteristics, this paper presents: 1) a single mathematical analysis of instantaneous relations applicable to all classes of operation of push-pull audio vacuum tube amplifiers; 2) a mathematical derivation, applicable to all classes of operation, of the composite load line equation and a study of the amplifier frequency response both at medium and low frequencies, with third and

  7. Uniplanar microwave balanced mixers and amplifiers 

    E-print Network

    Hsu, Pang-Cheng

    1995-01-01

    are also developed. The first amplifier is designed in the unconditionally stable frequency range with the gain between 3.5 and 5 dB. The measured output 1-dB compression point (P1dB) is 14 dBm at 6 GHz and 19 dBm at 10 GHz. The other amplifier is designed...

  8. 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.

  9. Theoretical proposal for a unidirectional optical amplifier

    Microsoft Academic Search

    Minoru Yamada

    1999-01-01

    The possibility of achieving a unidirectional optical amplifier is theoretically predicted with a model in the vacuum environment. The operation of this amplifier is based on the transfer of the kinetic energy of an electron beam to an optical one where both are propagating in the same direction. The optical beam propagates in a dielectric waveguide where it partly penetrates

  10. Simple, Stable and Reliable Transistorized DC Amplifiers

    Microsoft Academic Search

    L. C. Hale; J. S. Nisbet; C. K. Wilk

    1965-01-01

    A transistor dc feedback voltage amplifier using a differential input stage followed by a single common emitter stage is analyzed to obtain the gain and drift rate dependence on temperature. It is found that under typical restraints on allowable input terminal current, the open loop gain of such an amplifier is restricted to a value only somewhat greater than twenty

  11. Electron beam semiconductor S-band amplifier

    Microsoft Academic Search

    L. A. Roberts

    1976-01-01

    This report discusses results of an investigation leading to the development of a pulsed 1 kilowatt peak power (EBS) RF amplifier operating at 3.2 GHz. The feasibility of building pulsed power (EBS) amplifiers in the 3 GHz frequency range was demonstrated. Techniques have been worked out for designing and constructing semiconductor diodes capable of maintaining their electrical characteristics under high

  12. Parametric amplifiers driven by two pump waves

    Microsoft Academic Search

    C. J. McKinstrie; S. Radic; A. R. Chraplyvy

    2002-01-01

    The theory of parametric amplifiers driven by two pump waves is developed. By choosing the pump wavelengths judiciously, one can design an amplifier that produces uniform exponential gain over a range of wavelengths that extends at least 30 nm on either side of the average pump wavelength

  13. Chemically induced unfolding of bovine serum albumin by urea and sodium dodecyl sulfate: a spectral study with the polarity-sensitive charge-transfer fluorescent probe (E)-3-(4-methylaminophenyl)acrylic acid methyl ester.

    PubMed

    Ghosh, Shalini; Guchhait, Nikhil

    2009-07-13

    Sensitivity of the charge-transfer (CT) band of the fluorescence probe (E)-3-(4-methylaminophenyl)acrylic acid methyl ester (MAPAME) towards the polarity of its immediate environment is employed to investigate the binding interaction of the probe with bovine serum albumin (BSA) and uncoiling of BSA by the denaturants urea and sodium dodecyl sulfate micelles. Binding of the probe with BSA produces a blue shift and enhanced intensity of the CT emission band which clearly point toward a decrease in polarity of the immediate environment of MAPAME. This is expected, since binding with BSA moves the probe from a polar water environment to a much less polar, hydrophobic protein interior, where the CT band is expected to be blue-shifted. Higher intensity arises due to fewer non-radiative decay paths available to the probe in the hydrophobic protein environment. Chemically induced unfolding of BSA by urea and sodium dodecyl sulfate is tracked by monitoring the induced spectral changes of the protein-bound probe MAPAME. Red-edge excitation shift or REES, fluorescence resonance energy transfer (FRET) and anisotropy measurements are used to investigate and monitor these binding and unfolding processes. PMID:19466702

  14. 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.

  15. Front-end electronics for CsI based charged particle array for the study of reaction dynamics

    NASA Astrophysics Data System (ADS)

    Jhingan, Akhil; Sugathan, P.; Kaur, Gurpreet; Kapoor, K.; Saneesh, N.; Banerjee, T.; Singh, Hardev; Kumar, A.; Behera, B. R.; Nayak, B. K.

    2015-06-01

    The characteristics and performance of a new detector system based on CsI(TI) scintillators, and its front-end electronics are presented. The detector system has been developed for the detection of light charged particles to investigate fusion-fission dynamics, and will also serve as ancillary detector for an array of neutron detectors. CsI scintillators are read by photo-diodes. The main feature of the array is its compact and simple high density front-end electronics which includes custom developed low noise charge sensitive preamplifiers (with very low power consumption for operation inside vacuum), NIM differential drivers, and commercially available Mesytec amplifiers with two different time constants for particle identification using a ballistic deficit technique.

  16. Performance of positive-tone chemically amplified resists for next-generation photomask fabrication

    Microsoft Academic Search

    Toshikazu Segawa; Masa-Aki Kurihara; Shiho Sasaki; Hiroyuki Inomata; Naoya Hayashi; Hisatake Sano

    1997-01-01

    Several types of chemically amplified resists (CARs) have been evaluated in comparison with other types of resists. The evaluated CARs were found to have better performance than conventional resists and to satisfy the requirements for next generation reticle fabrication. Especially CARs have high sensitivity and high contrast enough to make photomasks with e-beam writers and have good dry-etch durability. We

  17. Operational amplifier-based micro eddy current sensor and its application in abrasive machining (honing)

    Microsoft Academic Search

    Fengqiang Gu; Xiaoyou Ye; Hongtang Gao; Heyan Wang; Jing Xie

    2010-01-01

    An operational amplifier-based micro eddy current sensor circuit is developed for improvement of sensitivity, reduction of power consumption and application in small mounting space. An eddy current sensor is designed on the optimized parameters in this circuit. Meanwhile, an eddy current sensor static calibration system is built by comparing to the measurement unit of Switzerland TESA Inductance Sensor TT80 of

  18. Polarization Independent Raman-Assisted Fiber Optical Parametric Amplifiers

    E-print Network

    Wai, Ping-kong Alexander

    Polarization Independent Raman-Assisted Fiber Optical Parametric Amplifiers S. H. Wang1 , Dawei, Raman scattering, optical parametric amplifiers. Abstract We propose and demonstrate a polarization independent Raman-assisted fiber optical parametric amplifier using depolarized Raman and parametric pumps

  19. POWER FLOW ANALYSIS OF ELECTROSTRICTIVE ACTUATORS DRIVEN BYSWITCHMODE AMPLIFIERS

    E-print Network

    Lindner, Douglas K.

    POWER FLOW ANALYSIS OF ELECTROSTRICTIVE ACTUATORS DRIVEN BYSWITCHMODE AMPLIFIERS Gregory A. Zvonar: smart structures, smart skin, switchmode amplifiers, power flow analysis, electrostrictive actuators is within the bandwidth of the amplifier. This analysis also reveals that the electrical power flow through

  20. 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.

  1. Improving Precision of Proximity Ligation Assay by Amplified Single Molecule Detection

    PubMed Central

    Fredriksson, Simon; Landegren, Ulf; Nilsson, Mats

    2013-01-01

    Proximity ligation assay (PLA) has been proven to be a robust protein detection method. The technique is characterized by high sensitivity and specificity, but the assay precision is probably limited by the PCR readout. To investigate this potential limitation and to improve precision, we developed a digital proximity ligation assay for protein measurement in fluids based on amplified single molecule detection. The assay showed significant improvements in precision, and thereby also detection sensitivity, over the conventional real-time PCR readout. PMID:23874999

  2. RF drivers for the Bevalac injector final stage RF amplifiers

    Microsoft Academic Search

    D. Howard; J. Calvert; M. Hui; A. Lindner; N. Kellogg; W. Ridgeway; K. Woolfe

    1991-01-01

    A 200-MHz intermediate power amplifier system, comprising of four separate chassis or cavity amplifiers is being developed as a driver stage for the Bevalac injector final RF amplifiers. The initial stage is a 200-W, solid-state, RF amplifier with 44 dB of gain. The two succeeding stages are cavity amplifiers that incorporate vacuum tubes. The first of the tube-type amplifiers is

  3. 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.

  4. 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.

  5. 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.

  6. 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 ?(t) is S?(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 simulation. To conclude, this article is intended as a tutorial, a review, and a systematic treatise on the subject, supported by extensive experiments. PMID:23221210

  7. Single mode terahertz quantum cascade amplifier

    NASA Astrophysics Data System (ADS)

    Ren, Y.; Wallis, R.; Shah, Y. D.; Jessop, D. S.; Degl'Innocenti, R.; Klimont, A.; Kamboj, V.; Beere, H. E.; Ritchie, D. A.

    2014-10-01

    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.

  8. Charge control of electrostatically actuated micromechanical infrared Fabry-Pérot filters

    NASA Astrophysics Data System (ADS)

    Lehmann, Sebastian; Ebermann, Martin; Neumann, Norbert

    2013-10-01

    In this work, the applicability of charge controlled electrostatically tuneable optical filters is investigated. The filters are based on a Fabry-Pérot architecture, fabricated in a bulk micromachining process. Compared to surface micromachined devices, this design opens a path to higher optical performance due to the high planarity and low roughness of substrates but also introduces the drawback of acceleration sensitivity because of a moving mass. The common way of tuning those electrostatic actuators by applying constant voltages decreases the effective stiffness of the system and thus further increases this sensitivity for large deflections. In addition, the tuning range is limited to one third of the initial electrode spacing due to the pull-in effect. Therefore, designing voltage-controlled electrostatic actuators of such optical filters result in tough tradeoffs between initial electrode spacing, spring stiffness, supply voltage and chip area. In order to overcome the limitation of the tuning range and relax these tradeoffs, controlling the charge instead of voltage by using a switched capacitor amplifier is examined. Experiments have shown that it is possible to obtain a stable relative displacement of up to 60% limited by reflector tipping. Measuring gravity impact confirmed the expected reduced deflection dependency. Thus, it is possible to downsize the initial electrode spacing by 45% and the spring stiffness by 40% while achieving the same optical tuning range and acceleration sensitivity as in voltage mode. However, because of reflector tilting and the associated filter bandwidth degradation, a further tradeoff arises when using relative deflections greater 40 %.

  9. Dye-sensitized solar cells

    Microsoft Academic Search

    Michael Grätzel

    2003-01-01

    The dye-sensitized solar cells (DSC) provides a technically and economically credible alternative concept to present day p–n junction photovoltaic devices. In contrast to the conventional systems where the semiconductor assume both the task of light absorption and charge carrier transport the two functions are separated here. Light is absorbed by a sensitizer, which is anchored to the surface of a

  10. A nanoscale DNA-Au dendrimer as a signal amplifier for the universal design of functional DNA-based SERS biosensors.

    PubMed

    Sun, Yun-Hong; Kong, Rong-Mei; Lu, Dan-Qing; Zhang, Xiao-Bing; Meng, Hong-Min; Tan, Weihong; Shen, Guo-Li; Yu, Ru-Qin

    2011-04-01

    The use of a nanoscale DNA-Au dendrimer as a signal amplifier was proposed for the universal design of functional DNA-based ultra-sensitive SERS biosensors. This novel design combines the high specificity of functional DNA with the high sensitivity of surface-enhanced Raman scattering (SERS) spectroscopy, resulting in sensitivity superior to that of previously reported sensors. PMID:21321698

  11. 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.

  12. Enhanced photovoltaic performance utilizing effective charge transfers and light scattering effects by the combination of mesoporous, hollow 3D-ZnO along with 1D-ZnO in CdS quantum dot sensitized solar cells.

    PubMed

    Chetia, Tridip Ranjan; Barpuzary, Dipankar; Qureshi, Mohammad

    2014-05-28

    A combination of 3-dimensional (3D) hollow mesoporous ZnO microspheres (ZnO HMSP) and vertically grown one-dimensional ZnO nanowires (1D ZnO NWs) on a fluorine doped tin oxide (FTO) coated glass substrate has been investigated as a photoanode for a CdS quantum dot-sensitized solar cell (QSSC). A comparative study of the photovoltaic performance of the solar cell with devices fabricated with pristine ZnO HMSPs and ZnO NWs was carried out. The proposed photovoltaic device exhibits an enhancement in power conversion efficiency (PCE) upto ?74% and ?35%, as compared to the 1D ZnO NW and ZnO HMSP based solar cells. The maximum incident photon-to-current conversion efficiency (IPCE) for the solar cell was observed to be ?40%, whereas for the devices fabricated with bare ZnO HMSP and ZnO NW the IPCE were only ?32% and ?19%, respectively. The enhanced photovoltaic performance of the solar cell is attributed to the high Brunauer-Emmett-Teller (BET) surface area, efficient light-scattering effects and facilitated diffusion of the electrolyte for better functioning of the redox couple (S(2-)/Sn(2-)) in the hybrid photoanode. Moreover, a faster electron transport through 1D ZnO NWs provides better charge collection from the photoactive layer, which leads to an increase in the short circuit current density of the device. The present study highlights the design and development of a new hybrid photoanode for solar harvesting. PMID:24730023

  13. Amplified impedimetric aptasensor based on gold nanoparticles covalently bound graphene sheet for the picomolar detection of ochratoxin A.

    PubMed

    Jiang, Ling; Qian, Jing; Yang, Xingwang; Yan, Yuting; Liu, Qian; Wang, Kan; Wang, Kun

    2014-01-01

    An amplified electrochemical impedimetric aptasensor for ochratoxin A (OTA) was developed with picomolar sensitivity. A facile route to fabricate gold nanoparticles covalently bound reduced graphene oxide (AuNPs-rGO) resulted in a large number of well-dispersed AuNPs on graphene sheets with tremendous binding sites for DNA, since the single rGO sheet and each AuNP can be loaded with hundreds of DNA strands. An aptasensor with sandwich model was fabricated which involved thiolated capture DNA immobilized on a gold electrode to capture the aptamer, then the sensing interface was incubated with OTA at a desired concentration, followed by AuNPs-rGO functionalized reporter DNA hybridized with the residual aptamers. By exploiting the AuNPs-rGO as an excellent signal amplified platform, a single hybridization event between aptamer and reporter DNA was translated into more than 10(7) redox events, leading to a substantial increase in charge-transfer resistance (Rct) by 7~ orders of magnitude compared with that of the free aptamer modified electrode. Such designed aptasensor showed a decreased response of Rct to the increase of OTA concentrations over a wide range of 1 pg mL(-1)-50 ng mL(-1) and could detect extremely low OTA concentration, namely, 0.3 pg mL(-1) or 0.74 pM, which was much lower than that of most other existed impedimetric aptasensors. The signal amplification platform presented here would provide a promising model for the aptamer-based detection with a direct impedimetric method. PMID:24331048

  14. A sensitive MNMOS structure for optical storage

    Microsoft Academic Search

    M. S. Shivaraman; O. Engstrom

    1990-01-01

    A sensitive device structure for the storage of optical signals is presented. It is based on an indium tin oxide - silicon nitride - aluminum - silicon dioxide - silicon (MNMOS) combination. The light signal is transformed to electric charge through optical excitation of charge carriers in the two metal layers. The charge is transported in the nitride conduction and

  15. Increasing dynamic range in microwave parametric amplifiers

    NASA Astrophysics Data System (ADS)

    Mutus, J.; Barends, R.; Bochmann, J.; Campbell, B.; Chen, Y.; Chiaro, B.; Jeffrey, E.; Kelly, J.; Mariantoni, M.; Megrant, A.; Neill, C.; O'Malley, P.; Ohya, S.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T.; Cleland, A. N.; Martinis, J. M.

    2013-03-01

    Parametric amplifiers have long been of interest in quantum information due to their high gain and near quantum limited performance. In collaboration with UC Berkeley, we are improving upon their proven parametric amplifier design, which consists of a lumped element LC resonator, with a SQUID providing a tunable nonlinear inductance. In order to improve the dynamic range of these amplifiers, multiple SQUIDs are used in series in order to distribute the non-linearity across many junctions. We report on the design of a single-ended amplifier using our 7-layer fabrication process, combining photo and electron beam lithography. We explore the experimental optimization of such a design, specifically the impact of adding additional SQUIDs on overall device performance.

  16. A novel wideband gyrotron travelling wave amplifier

    E-print Network

    Sirigiri, Jagadishwar R. (Jagadishwar Rao), 1973-

    2003-01-01

    We present the design and the experimental results of a novel wideband quasioptical Gyrotron Traveling Wave Tube (gyro-TWT) amplifier and the first Vacuum Electron Device (VED) with a Photonic Band Gap (PBG) structure. The ...

  17. Microwave diode amplifiers with low intermodulation distortion

    NASA Technical Reports Server (NTRS)

    Cooper, H. W.; Cohn, M.; Buck, D. C.

    1975-01-01

    Distortions can be greatly reduced in narrow-band applications by using the second harmonic. The ac behavior of simplified diode amplifier has negative resistance depending on slope of equivalent I-V curve.

  18. Sensor/amplifier for weak light sources

    NASA Technical Reports Server (NTRS)

    Desmet, D. J.; Jason, A. J.; Parr, A. C.

    1980-01-01

    Light sensor/amplifier circuit detects weak light converts it into strong electrical signal in electrically noisy environment. Circuit is relatively simple and uses inexpensive, readily available components. Device is useful in such applications as fire detection and photographic processing.

  19. 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.

  20. 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.

  1. DSP Modulated Class D Audio Amplifier

    E-print Network

    Klein, Andrew G.

    by: Professor Andrew Klein #12;ii Abstract The goal of this project was to create an 80W, 95-state digital modulator, an H-bridge amplifier, and a passive filter and was capable of accepting both digital

  2. New class of continuous wave parametric amplifiers

    Microsoft Academic Search

    S. Radic; C. J. McKinstrie; A. R. Chraplyvy; G. Raybon; J. C. Centanni; C. G. Jorgensen; K. Brar; C. Headley

    2002-01-01

    A new class of optical fiber parametric amplifier is demonstrated. Modulational instability coupling between optical pumps operating in the anomalous and normal dispersion regimes is used to achieve broad, flat CW parametric gain in excess of 40 dB.

  3. Analysis and characterization of semiconductor optical amplifiers for application in photonic switching networks

    NASA Astrophysics Data System (ADS)

    Rudge Barbosa, F.; Maia, Decio; Moschim, E.

    2013-12-01

    Results and analysis of semiconductor optical amplifiers (SOA) are presented as applied to Photonic switching nodes in OPS/OBS future optical networks. Detailed characterization is provided to investigate physical constraints of optical power, gain and noise figure of SOAs. Two different lasers, one external cavity tunable laser and one DFB laser, verify that although the SOA gain is not significantly sensitive to input source a clear difference on the noise figure (NF) is observed. Another important result is that by limiting the average number of hops in the network accumulated ASE power from the amplifiers should not impair signal quality.

  4. Electron paramagnetic resonance W-band spectrometer with a low-noise amplifier

    Microsoft Academic Search

    M. J. Nilges; A. I. Smirnov; R. B. Clarkson; R. L. Belford

    1999-01-01

    The Mark II W-band (94 GHz) EPR spectrometer with a low-noise millimeter-wave amplifier is described. The microwave bridge\\u000a is of a high-sensitivity homodyne design. Signal-to-noise ratios were measured for a number of detectors with and without\\u000a the low-noise amplifier. The signal-to-noise ratio was determined not only by the type of detector but also how well it was\\u000a matched. Without a

  5. Computer-oriented synthesis of wide-band non-uniform negative resistance amplifiers

    NASA Technical Reports Server (NTRS)

    Branner, G. R.; Chan, S.-P.

    1975-01-01

    This paper presents a synthesis procedure which provides design values for broad-band amplifiers using non-uniform negative resistance devices. Employing a weighted least squares optimization scheme, the technique, based on an extension of procedures for uniform negative resistance devices, is capable of providing designs for a variety of matching network topologies. It also provides, for the first time, quantitative results for predicting the effects of parameter element variations on overall amplifier performance. The technique is also unique in that it employs exact partial derivatives for optimization and sensitivity computation. In comparison with conventional procedures, significantly improved broad-band designs are shown to result.

  6. [Experimental study on harmonic detection of methane by use of a digital lock-in amplifier].

    PubMed

    Dong, Lei; MA, Wei-Guang; Yin, Wang-Bao; Li, Chang-yong; Jia, Suo-tang

    2005-03-01

    The harmonic detection of methane at 6105.3694 cm(-1) was measured by use of a digital lock-in amplifier (SR830) remotely controlled by a computer. The programme was written by Visual Basic 6.0 because it has strong function and a friendly appearance. The experimental results are in agreement with theoretical analysis, which fully confirms that a better signal-to-noise ratio (SNR) can be achieved in the high-harmonics detection of trace gases by the digital lock-in amplifier. The method can be applicable to the highly sensitive detection of pollution gases. PMID:16013337

  7. A Si bipolar monolithic RF bandpass amplifier

    Microsoft Academic Search

    N. M. Nguyen; R. G. Meyer

    1992-01-01

    The application of monolithic inductors to the realization of Si bipolar monolithic RF amplifiers is investigated. As a test vehicle, a bipolar monolithic bandpass amplifier was fabricated and characterized. A 4-nH silicon integrated inductor was used to achieve a peak S 21 gain of 8 dB, a simulated noise figure of 6.4 dB, and a matched input impedance of 50

  8. Thulium-doped tellurite fiber amplifier

    Microsoft Academic Search

    E. R. M. Taylor; L. N. Ng; J. Nilsson; R. Caponi; A. Pagano; M. Potenza; B. Sordo

    2004-01-01

    Gain in the S-band is demonstrated in a thulium-doped tellurite fiber amplifier using dual pump and bidirectional pumping schemes. Two pump schemes were employed: 795\\/1064 and 1047\\/1550 nm. The gain profile is broader than achieved in a fluoride fiber and overlaps with the C-band of the erbium-doped fiber amplifier. We reach a fiber-to-fiber gain of 11 dB and an internal

  9. 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.

  10. A strain amplifying piezoelectric MEMS actuator

    Microsoft Academic Search

    Nicholas J. Conway; Zachary J. Traina; Sang-Gook Kim

    2007-01-01

    A micro-scale, high-force, large displacement and low-voltage piezoelectric actuator has been developed using a compact strain amplifying flextensional mechanism. The device is fabricated using an SU-8 beam structure as an external amplifying mechanism for a thin-film PZT strip (area 11.4 × 10-4 cm2, thickness 0.4 µm) sandwiched between Pt top and bottom electrodes. Each actuator 'cell' can be arrayed in

  11. A strain amplifying piezoelectric MEMS actuator

    Microsoft Academic Search

    Nicholas J Conway; Zachary J Traina; Sang-Gook Kim

    2007-01-01

    A micro-scale, high-force, large displacement and low-voltage piezoelectric actuator has been developed using a compact strain amplifying flextensional mechanism. The device is fabricated using an SU-8 beam structure as an external amplifying mechanism for a thin-film PZT strip (area 11.4 × 10?4 cm2, thickness 0.4 µm) sandwiched between Pt top and bottom electrodes. Each actuator ‘cell’ can be arrayed in

  12. Optoelectronic Class AB Microwave Power Amplifier

    Microsoft Academic Search

    Chih-Jung Huang; R. M. O'Connell

    2006-01-01

    Recent power amplifiers for transmit\\/receive (TR) modules have been configured in the Class AB or push-pull mode with a theoretical efficiency of 78.5% and an operational efficiency of only 20% at X-band (8-12.5 GHz) frequencies. In this paper, we present results of a simulation study of a new scheme of power amplifier, in particular, an optoelectronic (OE) Class AB push-pull

  13. Iterated Solid-State Microwave Power Amplifier

    Microsoft Academic Search

    S. F. Paik

    1972-01-01

    A theoretical analysis is presented of a solid-state power amplifier consisting of a unidirectional transmission line loaded by a series of negative-resistance diodes. Numerical calculations of the large-signal amplifier characteristics are carried out assuming a cubic nonlinear relationship between the diode current and the RF voltage. Diode parameters used in these calculations are chosen to approximate those of available IMPATT

  14. Two-pump fiber parametric amplifiers

    Microsoft Academic Search

    S. Radic; C. J. McKinstrie

    2003-01-01

    The operational features of a two-pump fiber parametric amplifier cannot be matched by a conventional, single-pump device. New degrees of design freedom can be used to construct a gain-equalized amplifier operating over a broad spectral range. The two-pump device is characterized by four parametric bands that can be used for flexible, unimpaired signal conversion. Orthogonal-pump multiplexing in birefringent highly nonlinear fiber is shown to

  15. Design of an auto-zeroed differential organic thin film field-effect transistor amplifier for sensor applications

    NASA Astrophysics Data System (ADS)

    Binkley, David M.; Verma, Nikhil; Crawford, Robert L.; Brandon, Erik J.; Jackson, Thomas N.

    2004-10-01

    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 pentacene 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.

  16. 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.

  17. 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.

  18. TESTING AND VERIFICATION OF A RF POWER AMPLIFIER CONTROL CIRCUIT

    E-print Network

    Trajkovic, Ljiljana

    TESTING AND VERIFICATION OF A RF POWER AMPLIFIER CONTROL CIRCUIT by David Ciampi A thesis submitted and Verification of a RF Power Amplifier Control Circuit Dr. John Jones Director School of Engineering Science, SFU and verification of a digital power amplifier controller (PAC). The power amplifier controller is an instantaneous

  19. Broadband RF feedback amplifier design with simple feedback network

    Microsoft Academic Search

    A. Marzuki; T. Zainal; A. Zulkifli; N. M. Noh; Z. A. A. Aziz

    2004-01-01

    The paper presents a simple and fast design technique for an RF feedback amplifier. The amplifier uses a series resistor and capacitor as the feedback element. An overview of the amplifier impedance analysis and the noise theory of the amplifier is presented. A high frequency passive component model is also presented. With a current consumption of 6 mA, the simulated

  20. 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.

  1. Self-imaging silicon Raman amplifier Varun Raghunathan1

    E-print Network

    Jalali. Bahram

    Self-imaging silicon Raman amplifier Varun Raghunathan1 , Hagen Renner2 , Robert R. Rice3 of Raman amplifiers and oscillators I. Oscillators," Appl. Phys. Lett. 6, 210-212 (1965). 7. P. Lallemand and N. Bloembergen, "Multimode effects in the gain of Raman amplifiers and oscillators II. Amplifiers

  2. Flip chip mountable optical waveguide amplifier for optical backplane systems

    Microsoft Academic Search

    Steffen Uhlig; Mats Robertsson

    2005-01-01

    A concept study of a planar optical waveguide amplifier is presented, where the amplifier is to be used in optical backplane or motherboard systems with planar polymer optical waveguides. The amplification device can be flip chip mounted on the backplane to pre-amplify an incoming signal, compensate optical losses due to signal routing, or post amplify an output signal. The hybrid

  3. Hybrid High Power Amplifiers for L-Band Space Application

    Microsoft Academic Search

    Corrado Florian; Francesco Scappaviva; R. P. Paganelli; I. Melczarsky; R. Cignani; M. Pirazzini; R. Giordani; M. Feudale; G. Vannini; F. Filicori

    2007-01-01

    This paper describes the design and implementation of 2 hybrid high power amplifiers at L band for a space application. Indeed, the amplifiers represent prototype test vehicles for a larger hybrid amplifier to be used as the final power stage in the transmitting chain of a T\\/R module of an L-band SAR antenna for earth observation. The amplifiers described in

  4. 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.

  5. Single-ion quantum lock-in amplifier.

    PubMed

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

    2011-05-01

    Quantum metrology uses tools from quantum information science to improve measurement signal-to-noise ratios. The challenge is to increase sensitivity while reducing susceptibility to noise, tasks that are often in conflict. Lock-in measurement is a detection scheme designed to overcome this difficulty by spectrally separating signal from noise. Here we report on the implementation of a quantum analogue to the classical lock-in amplifier. All the lock-in operations--modulation, detection and mixing--are performed through the application of non-commuting quantum operators to the electronic spin state of a single, trapped Sr(+) ion. We significantly increase its sensitivity to external fields while extending phase coherence by three orders of magnitude, to more than one second. Using this technique, we measure frequency shifts with a sensitivity of 0.42 Hz Hz(-1/2) (corresponding to a magnetic field measurement sensitivity of 15 pT Hz(-1/2)), obtaining an uncertainty of less than 10 mHz (350 fT) after 3,720 seconds of averaging. These sensitivities are limited by quantum projection noise and improve on other single-spin probe technologies by two orders of magnitude. Our reported sensitivity is sufficient for the measurement of parity non-conservation, as well as the detection of the magnetic field of a single electronic spin one micrometre from an ion detector with nanometre resolution. As a first application, we perform light shift spectroscopy of a narrow optical quadrupole transition. Finally, we emphasize that the quantum lock-in technique is generic and can potentially enhance the sensitivity of any quantum sensor. PMID:21544142

  6. Noise analysis for position-sensitive detectors

    Microsoft Academic Search

    Chellappan Narayanan; A. Bruce Buckman; Ilene Busch-Vishniac

    1997-01-01

    A study of the different noise sources in a position sensitive detector (PSD)-transimpedance amplifier (TIA) sensing system is presented and the dominant noise sources are identified. The effect of these noise sources on the position detection capability of the sensing system is analyzed. An expression derived for the position resolution of the phase method of position detection reveals the position

  7. Exponential Gain and Saturation of a Self-Amplified Spontaneous Emission Free-Electron Laser

    Microsoft Academic Search

    S. V. Milton; E. Gluskin; N. D. Arnold; C. Benson; W. Berg; S. G. Biedron; M. Borland; Y.-C. Chae; R. J. Dejus; P. K. Den Hartog; B. Deriy; M. Erdmann; Y. I. Eidelman; M. W. Hahne; Z. Huang; K.-J. Kim; J. W. Lewellen; Y. Li; A. H. Lumpkin; O. Makarov; E. R. Moog; A. Nassiri; V. Sajaev; R. Soliday; B. J. Tieman; E. M. Trakhtenberg; G. Travish; I. B. Vasserman; N. A. Vinokurov; X. J. Wang; G. Wiemerslage; B. X. Yang

    2001-01-01

    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

  8. Periodic Permanent-Magnet Quadrupole Focusing Lattices for Linear Electron-Beam Amplifier Applications

    Microsoft Academic Search

    David K. Abe; Rami A. Kishek; John J. Petillo; David P. Chernin; Baruch Levush

    2009-01-01

    Periodic lattices of permanent-magnet quadrupoles (PMQs) have the potential to provide the strong focusing necessary to transport high-current space-charge-dominated electron beams commonly used in vacuum electronic power amplifiers. We describe a new design methodology and computational tools to produce optimized PMQ lattices, verifying the results with fully 3-D particle simulations of design examples. These examples include a PMQ system with

  9. Cryogenic amplifier for fast real-time detection of single-electron tunneling I. T. Vink,a

    E-print Network

    to the operation of the rf single- electron transistor.15 In theory such a "rf-QPC" allows for single-shot chargeCryogenic amplifier for fast real-time detection of single-electron tunneling I. T. Vink,a T. The authors use this setup to monitor single-electron tunneling to and from an adjacent quantum dot

  10. Implementing an External Charge Injection System into the ILC-SiD KPiX ASIC for Charged-Particle Tracking Characterize

    NASA Astrophysics Data System (ADS)

    Schier, Sheena; Schumm, Bruce

    2012-03-01

    KPiX 9 is a 512 channel ASIC designed by SLAC that is competing to perform detector readout for the International Linear Collider (ILC) and is currently the only readout chip that aims to fulfill both tracking and calorimetry needs for the ILC. To achieve the efficiency standard set for charged-particle tracking in the ILC a 1fC threshold; therefore, we need to understand the gain to 1fC as well. We connected an ECIS to 4 of the 6 bonded out channels in order to inject charges down to 1fC without distortion from internal calibration offsets. During the ILC beam spill, KPiX acquires up to 4 signals; our current analysis is restricted to the first acquisition only. Only 3 of the 4 ECIS channels were observable and displayed charge sensitivity down to around 2.5fC. The expected gain is -75mV/fC and the expected zero offset is at 2500mV; the gains and offsets are inverted by the amplifier. The average gain for the sensitive region is -72.8mV/fC with RMS 1.15mV/fC, with average voltage offset 2587mV with RMS 37.9mV. The gain curves are consistent and flatten out together along the charge axis. The average minimum threshold is 2.5fC with RMS 0.11fC. We conclude that the first acquisition of the KPiX ASIC is not efficient for ILC tracking and are now working to understand the other three acquisitions.

  11. Raman and loss induced quantum noise in depleted fiber optical parametric amplifiers.

    PubMed

    Friis, S M M; Rottwitt, K; McKinstrie, C J

    2013-12-01

    We present a semi-classical approach for predicting the quantum noise properties of fiber optical parametric amplifiers. The unavoidable contributors of noise, vacuum fluctuations, loss-induced noise, and spontaneous Raman scattering, are included in the analysis of both phase-insensitive and phase-sensitive amplifiers. We show that the model agrees with earlier fully quantum approaches in the linear gain regime, whereas in the saturated gain regime, in which the classical equations are valid, we predict that the amplifier increases the signal-to-noise ratio by generating an amplitude-squeezed state of light. Also, in the same process, we analyze the quantum noise properties of the pump, which is difficult using standard quantum approaches, and we discover that the pump displays complicated dynamics in both the linear and the nonlinear gain regimes. PMID:24514485

  12. Measurement of resonant and nonresonant induced refractive index changes in Yb-doped fiber grating amplifier.

    PubMed

    Shapira, Y P; Oscar, D; Spektor, B; Smulakovsky, V; Horowitz, M

    2015-02-15

    We have measured the refractive index change (RIC) induced in a fiber Bragg grating (FBG) written in a Yb-doped fiber amplifier (YB-FBG) because of the amplifier pumping. The measurement was performed by exploiting the high sensitivity of the YD-FBG transmission to the RIC. We have separated between electronic and thermal contributions to the RIC based on the difference between the time-scales of the two effects. Because of high UV-induced loss in FBGs, the thermal contribution to the RIC is increased, in comparison with previously published work, where no grating was written in the fiber amplifier. The measurement method allows us to find the sign of each contribution to the RIC, and it requires only a few centimeters of fiber. Optimal pumping scheme for reducing the RIC in a YB-FBG is studied. PMID:25680141

  13. 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

  14. Demonstration of phase-regeneration of DPSK signals based on phase-sensitive amplification

    Microsoft Academic Search

    Kevin Croussore; Inwoong Kim; Yan Han; Cheolhwan Kim; Guifang Li; Stojan Radic

    2005-01-01

    Amplification and simultaneous phase regeneration of DPSK signals is demonstrated using a phase-sensitive amplifier. Phase-sensitive gain is achieved in a Sagnac fiber interferometer comprised of nonpolarization maintaining, highly nonlinear fiber operating in the un-depleted pump regime. Both the pump and signal are RZ-DPSK pulse trains. The amplifier is capable of producing greater than 13 dB of phase-sensitive gain for an

  15. Ge-on-SOI-Detector\\/Si-CMOS-Amplifier Receivers for High-Performance Optical-Communication Applications

    Microsoft Academic Search

    Steven J. Koester; Clint L. Schow; Laurent Schares; Gabriel Dehlinger; Jeremy D. Schaub; Fuad E. Doany; Richard A. John

    2007-01-01

    In this paper, an overview and assessment of high-performance receivers based upon Ge-on-silicon-on-insulator (Ge-on-SOI) photodiodes and Si CMOS amplifier ICs is provided. Receivers utilizing Ge-on-SOI lateral p-i-n photodiodes paired with high-gain CMOS amplifiers are shown to operate at 15 Gb\\/s with a sensitivity of -7.4 dBm (BER=10-12) while utilizing a single supply voltage of only 2.4 V. The 5-Gb\\/s sensitivity

  16. TRANSISTORIZED PULSE AMPLIFIERS. 3. A TRANSISTOR AMPLIFIER FOR USE WITH METHANE PROPORTIONAL COUNTERS

    Microsoft Academic Search

    Waugh; J. B. S

    1959-01-01

    A transistor pulse amplifier for use with methane proportional counters ; is described. The counter operation and the characteristics of the electrical ; output signals are described. Voltage and current pulse waveforms are related, ; and the use of the short duration current pulse to obtaia a smaller resolving ; time amplifier is pointed out. The practical amplifler uses low

  17. Charge Challenge

    NSDL National Science Digital Library

    University of Kansas

    2006-01-01

    In this activity, learners explore how objects can have positive, negative, or neutral charges, which attract, repel and move between objects. Learners charge various materials and observe their interactions. Winter is an ideal time to perform these experiments (because there is less water vapor in the air); if it is humid, use a hair dryer to dry the objects, surfaces, and air around the work area.

  18. Simulations of Surface Effects and Electron Emission from Diamond-Amplifier Cathodes

    SciTech Connect

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

    2011-09-30

    Emission of electrons in diamond experiments based on the promising diamond-amplifier concept was recently demonstrated. Transmission mode experiments have shown the potential to realize over two orders of magnitude charge amplification. However, the recent emission experiments indicate that surface effects should be understood in detail to build cathodes with optimal properties. We have made progress in understanding secondary electron generation and charge transport in diamond with models we implemented in the VORPAL particle-in-cell computational framework. We introduce models that we have been implementing for surface effects (band bending and electron affinity), charge trapping, and electron emission from diamond. Then, we present results from 3D VORPAL diamond-vacuum simulations with the integrated capabilities on generating electrons and holes, initiated by energetic primary electrons, charge transport, and then emission of electrons from diamond into vacuum. Finally, we discuss simulation results on the dependence of the electron emission on diamond surface properties.

  19. Injection- Seeded Optoplasmonic Amplifier in the Visible

    NASA Astrophysics Data System (ADS)

    Gartia, Manas Ranjan; Seo, Sujin; Kim, Junhwan; Chang, Te-Wei; Bahl, Gaurav; Lu, Meng; Liu, Gang Logan; Eden, J. Gary

    2014-08-01

    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.

  20. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, Lloyd A. (Livermore, CA); Dane, Clifford B. (Livermore, CA)

    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.

  1. 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.

  2. Demonstration of SQUID parametric amplifier. Final report, 1 October 1983-30 June 1988

    SciTech Connect

    Not Available

    1988-10-25

    Superconductive electronics incorporating Josephson junctions and SQUIDs (Superconducting Quantum Interference Devices) offers electronic systems of unrivaled sensitivity, speed, and efficiency which are important for the Navy and other DoD agencies. Under this contract, TRW has developed microwave parametric amplifiers based upon Josephson junction SQUIDs operating at X-band and K-band with noise levels approaching the quantum limit. This development makes possible microwave and millimeter-wave heterodyne receivers with noise temperatures below 10 k beyond 100 GHz. The amplifiers demonstrated here can serve as RF preamplifiers which set the noise figure in advanced of the mixer in receiver systems. As the front-end RF amplifier, this device will have much greater electromagnetic survivability than conventional mixer diodes. The amplifier developed under this contract served as the model for an integrated receiver under development for SDIO/IST. This research has demonstrated a 10-dB gain amplifier operated at X-band with measured noise temperature equal to 6 K.

  3. Tirasemtiv amplifies skeletal muscle response to nerve activation in humans

    PubMed Central

    Hansen, Richard; Saikali, Khalil G; Chou, Willis; Russell, Alan J; Chen, Michael M; Vijayakumar, Vipin; Stoltz, Randall R; Baudry, Stephane; Enoka, Roger M; Morgans, David J; Wolff, Andrew A; Malik, Fady I

    2014-01-01

    Introduction: In this study we tested the hypothesis that tirasemtiv, a selective fast skeletal muscle troponin activator that sensitizes the sarcomere to calcium, could amplify the response of muscle to neuromuscular input in humans. Methods: Healthy men received tirasemtiv and placebo in a randomized, double-blind, 4-period, crossover design. The deep fibular nerve was stimulated transcutaneously to activate the tibialis anterior muscle and produce dorsiflexion of the foot. The force–frequency relationship of tibialis anterior dorsiflexion was assessed after dosing. Results: Tirasemtiv increased force produced by the tibialis anterior in a dose-, concentration-, and frequency-dependent manner with the largest increases [up to 24.5% (SE 3.1), P?amplifies the response of skeletal muscle to nerve input in humans. This outcome provides support for further studies of tirasemtiv as a potential therapy in conditions marked by diminished neuromuscular input. Muscle Nerve 50: 925–931, 2014 PMID:24634285

  4. Short pulse free electron laser amplifier

    DOEpatents

    Schlitt, Leland G. (Livermore, CA); Szoke, Abraham (Fremont, CA)

    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.

  5. Membrane capacitance measurement using patch clamp with integrated self-balancing lock-in amplifier.

    PubMed

    Johnson, Stuart L; Thomas, Martin V; Kros, Corné J

    2002-02-01

    A lock-in amplifier was incorporated directly into the resistance and capacitance compensation circuitry of a patch clamp set-up, to allow exocytosis to be monitored in the whole-cell mode by measuring changes in cell membrane capacitance. The integration of these two systems enabled us to provide a novel operating mode, which we term the "track-in" mode, where the output signals from the lock-in amplifier are used to make compensating electronic adjustments of the resistance and capacitance control settings. The lock-in amplifier outputs remain near zero, and the control voltages generated by the feedback circuits provide linear and calibrated resistance and capacitance measurements. Results obtained from model cells and mouse inner hair cells show that this is achieved without loss of sensitivity or of significant time resolution compared with the conventional lock-in amplifier technique, whereas the sensitivity to switching phase errors is effectively eliminated. An automatic phase tracking system using a low-frequency dithering of the resistance control setting can nevertheless be used to preserve the correct switching phase if required. The track-in approach has considerable advantages over software implementations in terms of economy and convenience, since the resistance and capacitance signals can be recorded directly on any general-purpose data-acquisition system. PMID:11907834

  6. An optically pumped submillimeter wavelength regenerative amplifier

    NASA Technical Reports Server (NTRS)

    Galantowicz, T. A.

    1977-01-01

    An optically pumped regenerative submillimeter laser amplifier is described. The amplifier uses a waveguide cavity resonator, and a Fabry-Perot interferometer composed of two dielectric-coated mirrors serves as input and output port for the submillimeter signal. Use of two mirrors enabled obtaining variations of up to 6:1 in transmission by varying the mirror spacing. When the 373-micron transition in CH3CN is excited in the oscillator by the CO2 laser pump beam, the received signal with amplification is about nine times the unamplified signal.

  7. A analysis of the cathode coupled amplifier 

    E-print Network

    Hetlinger, Forrest James

    1951-01-01

    AN ANALySIS 0 TH CATHODE COOFL D ~iPLIPIER A Thesis by FORREST JACKS RETLING-. . R Approved as to style and content by: Chairman of Committee 'Head of Department August, 1951 AN ANALYSIS OF THE CATHODE COUPLED. AMPLIFIER by FORHEST JAMES... Circuit Introduction and Review of the Literature The cathode-coupled amplifier c1rcuit is shown in Fi~re l. It can be seen that, if the circuit is fed with signal voltages esl and es& of opposite phase, 1t will behave much like the ordinary push...

  8. Transportable setup for amplifier phase fidelity measurements

    NASA Astrophysics Data System (ADS)

    Tröbs, M.; Bogan, C.; Barke, S.; Kühn, G.; Reiche, J.; Heinzel, G.; Danzmann, K.

    2015-05-01

    One possible laser source for the Laser Interferometer Space Antenna (LISA) consists of an Ytterbium-doped fiber amplifier originally developed for inter-satellite communication, seeded by the laser used for the technology demonstrator mission LISA Pathfinder. LISA needs to transmit clock information between its three spacecraft to correct for phase noise between the clocks on the individual spacecraft. For this purpose phase modulation sidebands at GHz frequencies will be imprinted on the laser beams between spacecraft. Differential phase noise between the carrier and a sideband introduced within the optical chain must be very low. We report on a transportable setup to measure the phase fidelity of optical amplifiers.

  9. Membrane Thickness Sensitivity of Prestin Orthologs: The Evolution of a Piezoelectric Protein

    PubMed Central

    Izumi, Chisako; Bird, Jonathan E.; Iwasa, Kuni H.

    2011-01-01

    How proteins evolve new functionality is an important question in biology; prestin (SLC26A5) is a case in point. Prestin drives outer hair cell somatic motility and amplifies mechanical vibrations in the mammalian cochlea. The motility of mammalian prestin is analogous to piezoelectricity, in which charge transfer is coupled to changes in membrane area occupied by the protein. Intriguingly, nonmammalian prestin orthologs function as anion exchangers but are apparently nonmotile. We previously found that mammalian prestin is sensitive to membrane thickness, suggesting that prestin's extended conformation has a thinner hydrophobic height in the lipid bilayer. Because prestin-based motility is a mammalian specialization, we initially hypothesized that nonmotile prestin orthologs, while functioning as anion transporters, should be much less sensitive to membrane thickness. We found the exact opposite to be true. Chicken prestin was the most sensitive to thickness changes, displaying the largest shift in voltage dependence. Platypus prestin displayed an intermediate response to membrane thickness and gerbil prestin was the least sensitive. To explain these observations, we present a theory where force production, rather than displacement, was selected for the evolution of prestin as a piezoelectric membrane motor. PMID:21641306

  10. Robot-amplified manual exploration improves load identification

    PubMed Central

    Huang, F.C.; Patton, J.L.; Mussa-Ivaldi, F.A.

    2015-01-01

    We tested how manual exploration with anisotropic loading (Viscosity-Only (negative), Inertia-Only, or Combined-Load) influenced skill transfer to the isolated inertial load. Intact subjects (N=39) performed manual exploration with an anisotropic load before evaluation with prescribed circular movements. Combined-Load resulted in lower error (6.89±3.25%) compared to Inertia-Only (8.40±4.32%) and Viscosity-Only (8.17±4.13%) according to radial deviation analysis (% of trial mean radius). An analysis of sensitivity to load variation in normal and catch trials reveals performance differences were likely due to changes in feedforward mass compensation. Analysis of exploration movement revealed higher average speeds (12.0%) and endpoint forces (22.9%) with Combined-Load exploration compared to Inertia-Only. Our findings suggest that free movements amplified by negative viscosity can enhance the ability to identify changes in inertial loading.

  11. Electron Beam Emission from a Diamond-Amplifier Cathode

    SciTech Connect

    Chang Xiangyun; Wu Qiong; Ben-Zvi, Ilan; Burrill, Andrew; Kewisch, Jorg; Rao, Triveni; Smedley, John; Wang Erdong [Brookhaven National Laboratory, Upton, New York 11973 (United States); Muller, Erik M. [Stony Brook University, Stony Brook, New York 11794 (United States); Busby, Richard; Dimitrov, Dimitre [Tech-X Corporation, 5621 Arapahoe Avenue Suite A, Boulder, Colorado 80303 (United States)

    2010-10-15

    The diamond amplifier (DA) is a new device for generating high-current, high-brightness electron beams. Our transmission-mode tests show that, with single-crystal, high-purity diamonds, the peak current density is greater than 400 mA/mm{sup 2}, while its average density can be more than 100 mA/mm{sup 2}. The gain of the primary electrons easily exceeds 200, and is independent of their density within the practical range of DA applications. We observed the electron emission. The maximum emission gain measured was 40, and the bunch charge was 50 pC/0.5 mm{sup 2}. There was a 35% probability of the emission of an electron from the hydrogenated surface in our tests. We identified a mechanism of slow charging of the diamond due to thermal ionization of surface states that cancels the applied field within it. We also demonstrated that a hydrogenated diamond is extremely robust.

  12. Electron Beam Emission from a Diamond-Amplifier Cathode

    SciTech Connect

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

    2011-12-31

    The diamond amplifier (DA) is a new device for generating high-current, high-brightness electron beams. Our transmission-mode tests show that, with single-crystal, high-purity diamonds, the peak current density is greater than 400 mA/mm{sup 2}, while its average density can be more than 100 mA/mm{sup 2}. The gain of the primary electrons easily exceeds 200, and is independent of their density within the practical range of DA applications. We observed the electron emission. The maximum emission gain measured was 40, and the bunch charge was 50 pC/0.5 mm{sup 2}. There was a 35% probability of the emission of an electron from the hydrogenated surface in our tests. We identified a mechanism of slow charging of the diamond due to thermal ionization of surface states that cancels the applied field within it. We also demonstrated that a hydrogenated diamond is extremely robust.

  13. Quantum limit on noise in a Raman amplifier

    SciTech Connect

    Battle, P.R.; Swanson, R.C.; Carlsten, J.L. (Physics Department, Montana State University, Bozeman, Montana 59717 (US))

    1991-08-01

    Using Caves's theory on the quantum-noise limit in an amplifier, we consider the quantum limit on noise in a Raman amplifier. We show explicitly that the full quantum equations for the Raman interaction can be transformed into the general form for a quantum amplifier. In addition, we show that in the steady-state limit the Raman amplifier becomes a phase-insensitive amplifier. At this limit we find that the output signal-to-noise ratio is unity when one photon per mode is input. Thus we conclude that the Raman amplifier, in the phase-insensitive limit, will operate at the quantum-noise limit.

  14. Low phase noise oscillator using two parallel connected amplifiers

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard L.

    1987-01-01

    A high frequency oscillator is provided by connecting two amplifier circuits in parallel where each amplifier circuit provides the other amplifier circuit with the conditions necessary for oscillation. The inherent noise present in both amplifier circuits causes the quiescent current, and in turn, the generated frequency, to change. The changes in quiescent current cause the transconductance and the load impedance of each amplifier circuit to vary, and this in turn results in opposing changes in the input susceptance of each amplifier circuit. Because the changes in input susceptance oppose each other, the changes in quiescent current also oppose each other. The net result is that frequency stability is enhanced.

  15. Constraining the climate sensitivity of the global carbon cycle with paleoclimatic data (Invited)

    Microsoft Academic Search

    D. Frank; J. Esper; C. Raible; U. Büntgen; V. Trouet; B. Stocker; F. Joos

    2010-01-01

    The processes controlling the carbon flux and storage of the atmosphere, ocean, and terrestrial biosphere are temperature sensitive and are likely to provide a positive feedback leading to amplified anthropogenic warming. Due to this feedback, at interannual to Milankovitch timescales, warming of the climate system causes a net release of CO2 into the atmosphere; this in turn amplifies warming. But

  16. Large-screen projection displays with laser brightness amplifiers

    NASA Astrophysics Data System (ADS)

    Petrash, Gueorgii G.; Chvykov, Vladimir V.; Zemskov, Konstantin I.

    1997-05-01

    One of the most difficult problems of large-screen projection displays is overloading of a panel to be projected with illuminating light. The problem can be solved by using, on the way from a panel to be projected to a screen, an optical amplifier with high enough amplification. The prospects of using laser amplifiers in projection displays are discussed. Among all laser amplifiers the most suitable for application as optical amplifiers in projection systems are now pulsed metal vapor laser and metal halide laser amplifiers. They have rather high gain enabling amplification in the range from 102 to 104 and high average output power sufficient to illuminate a large screen. The main characteristics of these amplifiers are described. The results of experimental investigations of projection systems with copper, copper bromide, gold and some other metal vapor amplifiers are reported. In all cases good quality amplified images were obtained. Average power at the output of amplifiers was under typical conditions of operation comparable with the output power of a laser with the same amplifying element. Measurement of contrast of amplified images showed that under normal conditions of operation it is close to the contrast of the input picture even at strong saturation of the amplifying medium. The influence of the amplifier saturation is briefly discussed. The results of experiments with TV projection systems using two types of liquid crystal spatial light modulators are presented and prospects of large-screen projection displays development are discussed.

  17. A Wide Range Logarithmic Amplifier for Nerva

    Microsoft Academic Search

    G. A. Gilmour; C. E. Hardies; J. H. Wilson

    1965-01-01

    The design of a logarithmic amplifier with an operating range from 10-12 to 10-2 ampere is presented. A logarithmic characteristic within plus or minus 2 per cent of a decade over the 10 decade operating range of the instrument has been realized in the first model. Design improvements being incorporated in a second model include improved transient characteristics and an

  18. An Analysis of Magnetic Amplifiers with Feedback

    Microsoft Academic Search

    D. W. Ver Planck; M. Fishman; D. C. Beaumariage

    1949-01-01

    Two ways of obtaining feedback in magnetic amplifiers are studied. One, termed external feedback, employs a bridge rectifier and separate feedback coils, while the other, termed self feedback, uses two rectifiers so disposed that separate feedback windings are unnecessary. Commutation of the rectifiers, apparently not considered heretotore, is shown to be of major importance. The calculated currents are confirmed satisfactorily,

  19. FEA cathode experiments for microwave power amplifiers

    Microsoft Academic Search

    M. Garven; M. A. Kodis

    1996-01-01

    Summary form only given, as follows. The investigation of a new class of vacuum microelectronic, microwave power amplifiers based on field emitter array (FEA) technology is currently underway at the Naval Research Laboratory. FEAs offer instant activation, higher transconductance and higher current densities than thermionic cathodes and consequently higher performance gridded microwave power tubes should be possible. FEA microwave power

  20. Low Distortion RF Amplifier Video Pulses

    Microsoft Academic Search

    Lowell J. Fox

    1967-01-01

    Modern high energy particle accelerators require that the high power r.f. amplifiers generate r.f. waveforms which are essentially distortion free. This usually is accomplished through the use of very expensive and complicated high power regulation equipment. This paper will discuss an alternate, relatively simple means of obtaining this regulation through the use of a unique high vacuum switch tube used

  1. Ultra-wide bandwidth Raman amplifiers

    Microsoft Academic Search

    C. R. S. Fludger; V. Handerek

    2002-01-01

    We have discussed the design and noise performance issues for ultra-broadband Raman amplifiers. Superposition may be used to optimise pump wavelengths for flat gain spectra with bandwidths in excess of 100 nm, although numerical simulations are necessary to determine actual pump powers. Shorter wavelength signals suffer greater impairments than those at longer wavelengths due to increased ASE generation as signals

  2. Parametric power amplifiers: Old ideas, new technologies

    Microsoft Academic Search

    J. Stevenson Kenney

    2010-01-01

    This paper discusses the use of parametric circuits to achieve high power, high efficiency power amplification over wide bandwidths. A new architecture is proposed that uses an upconverting parametric amplifier as a polar modulator. In addition, applications of multiferroic materials to achieve wideband parametric amplification are discussed.

  3. Sodium channels amplify spine potentials Roberto Araya*

    E-print Network

    Eisenthal, Kenneth B.

    Sodium channels amplify spine potentials Roberto Araya* , Volodymyr Nikolenko* , Kenneth B for review January 25, 2007) Dendritic spines mediate most excitatory synapses in the brain. Past theoretical work and recent experimental evidence have suggested that spines could contain sodium channels. We

  4. Multiple-scale Analysis of Optical Amplifiers

    Microsoft Academic Search

    Malin Premaratne

    2008-01-01

    Short-pulse propagation in optical amplifiers has been widely studied for applications in optical signal processing and optical communications areas. Even though it is possible to integrate differential equations numerically, such implementations may not provide adequate insight into the device operation. We propose a systematic way to construct analytical solutions under pulsed conditions and show excellent agreement with numerically integrated results.

  5. Multiple scale analysis of semiconductor amplifiers

    Microsoft Academic Search

    Malin Premaratne

    2008-01-01

    Short-pulse propagation in optical amplifiers has been widely studied for applications in optical signal processing and optical communications areas. Even though it is possible to integrate differential equations numerically, such implementations may not provide adequate insight into the device operation. We propose a systematic way to construct analytical solutions under pulsed conditions and show excellent agreement with numerically integrated results.

  6. Fiber lasers and amplifiers by: Khanh Kieu

    E-print Network

    Kieu, Khanh

    Fiber lasers and amplifiers by: Khanh Kieu (02/28/2014) #12;Outlines · Introduction · History · Active fibers · Laser performances · Cladding pump technology · Fiber laser research at the College · 2005: Hänsch an Hall Nobel Prize in Physics awarded for contribution related to laser #12;Laser market

  7. Fiber lasers and amplifiers by: Khanh Kieu

    E-print Network

    Kieu, Khanh

    Fiber lasers and amplifiers by: Khanh Kieu (02/15/2013) #12;Outlines · Introduction · History · Active fibers · Laser performances · Cladding pump technology · Fiber laser research at the College · 2005: Hänsch an Hall Nobel Prize in Physics awarded for contribution related to laser #12;Laser market

  8. A novel wideband 140 GHz gyrotron amplifier

    E-print Network

    Joye, Colin D., 1980-

    2008-01-01

    The theory, design and experimental results of a wideband 140 GHz, 1 kW pulsed gyro-traveling wave amplifier are presented. The gyro- TWA operates in the HE(0,6) mode of a novel cylindrical confocal waveguide using a ...

  9. PCF based optical parametric oscillators and amplifiers

    Microsoft Academic Search

    J. D. Harvey; R. Leonhardt; H. C. Clark; R. Kruhlak; J. C. Knight; W. J. Wadsworth; P.St.J. Russell

    2003-01-01

    This study demonstrates photonic crystal fiber (PCF) based optical parametric oscillators and amplifiers. In the experiment, a wide range of fibres with varying zero GVD points around the visible red pump wavelength are used. The resulting upshifted sideband is in the yellow region of the spectrum of pumping in the normal dispersion regime (low group index mode) in agreement with

  10. Optical amplifier-powered quantum optical amplification

    SciTech Connect

    Jeffers, John [Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG (United Kingdom)

    2011-05-15

    I show that an optical amplifier, when combined with photon subtraction, can be used for quantum state amplification, adding noise at a level below the standard minimum. The device could be used to significantly decrease the probability of incorrectly identifying coherent states chosen from a finite set.

  11. Random Amplified Polymorphic DNA (RAPD) Markers

    Microsoft Academic Search

    Fevzi BARDAKCI

    Due to advances in molecular biology techniques, large numbers of highly informative DNA markers have been developed for the identification of genetic polymorphism. In the last decade, the random amplified polymorphic DNA (RAPD) technique based on the polymerase chain reaction (PCR) has been one of the most commonly used molecular techniques to develop DNA markers. RAPD markers are amplification products

  12. Optimized flashlamp pumping of disc amplifiers

    SciTech Connect

    Murray, J.E.; Powell, H.T.; Woods, B.W.

    1986-01-17

    Disk amplifier design for inertial fusion lasers has evolved with changing fusion-driver requirements from a primary emphasis on gain to a primary emphasis on efficiency. In this paper we compare Shiva and Nova amplifiers to a developmental amplifier (SSA) and show greater than a two-fold improvement in efficiency over past designs under all operating conditions. Experiments to optimize the efficiency of the SSA show that preionization of the flashlamps produces significant benefits and that the packing fraction of lamps is more important than the flashlamp reflector shape. They also show that the optimized flashlamp pulselength and reflector geometry depend on the desired stored energy in the laser medium. We have demonstrated a 7% storage efficiency at a stored fluence per disk of 0.5 J/cm/sup 2/ (stored energy density of 0.06 J/cm/sup 3/) and 4% at 2.0 J/cm/sup 2/ (0.25 J/cm/sup 3/). Comparison of SSA measurements with storage-efficiency calculations show that our flashlamp model accurately predicts the single-pass pumping of disk amplifiers. 24 refs., 22 figs.

  13. Magnetic Hysteresis Loop Tracer Using Operational Amplifiers

    Microsoft Academic Search

    Homer Fay

    1972-01-01

    A magnetic hysteresis loop tracer has been built to measure the magnetic properties of small cylindrical samples of nonconductive ferromagnets. Applied fields of 10 000 Oe peak amplitude are obtained from a water cooled solenoid driven at 60 Hz, and the change in flux is detected with a coil on the sample. Two operational amplifiers convert the input variables to

  14. Holding Charge

    NSDL National Science Digital Library

    Eric Muller

    1995-01-01

    In this trick, learners discover how to stick a straw to the palm of their hand, window door, or anywhere using static electricity. This activity introduces learners to negative and positive charges and shows how opposites attract. Note: this trick works best in low humidity (dry air).

  15. 1.55- micron polarization-insensitive optical amplifier with strain-balanced superlattice active layer

    NASA Astrophysics Data System (ADS)

    Godefroy, A.; Le Corre, A.; Clerot, F.; Salaun, S.; Loualiche, S.; Simon, J. C.; Henry, L.; Vaudry, C.; Keromnes, J. C.; Joulie, G.

    1995-05-01

    A polarization insensitive (sensitivity less than 1 dB) semiconductor optical amplifier has been realized at 1.55 micron. The active layer consists of a strain-balanced superlattice structure. Gain polarization insensitivity on a large bandwidth (60 nm) together with a 22.5-dB signal gain and a 11-dBm polarization-insensitive saturation output power are obtained.

  16. Beam Shaping of Single-Mode and Multimode Fiber Amplifier Arrays for Propagation Through Atmospheric Turbulence

    Microsoft Academic Search

    V. Jolivet; P. Bourdon; B. Bennai; L. Lombard; D. Goular; E. Pourtal; G. Canat; Y. Jaouen; B. Moreau; O. Vasseur

    2009-01-01

    We report experimental results and theoretical analysis of coherent beam combining with active phase control fiber beam shaping. An original optical configuration for target-in-the-loop single-mode fiber amplifier coherent combining through turbulence is presented, with a lambda\\/15 residual phase error. The experimental results and theoretical analysis demonstrate that detection subsystem aperture reduction is paramount to lower sensitivity to backward turbulence when

  17. Charge Pump Circuits: An Overview on Design Strategies and Topologies

    Microsoft Academic Search

    Gaetano Palumbo; Domenico Pappalardo

    2010-01-01

    Due to the continuous power supply reduction, charge pumps circuits are widely used in integrated circuits (ICs) devoted to several kind of applications such as smart power, nonvolatile memories, switched capacitor circuits, operational amplifiers, voltage regulators, SRAMs, LCD drivers, piezoelectric actuators, RF antenna switch controllers, etc. The main focus of this tutorial manuscript is to provide a deep understanding of

  18. Analysis of boron by charged particle bombardment

    Microsoft Academic Search

    N. Moncoffre

    1992-01-01

    The determination of boron concentration in thin films, semiconductors or other materials requires techniques providing good depth resolution and high sensitivities. For this purpose nuclear analysis techniques can be powerful tools and this paper presents a review of the nuclear reactions essentially with charged particles (p, alpha, d) that have been used (including charge particle activation analysis). Irradiation with neutrons

  19. A 250 GHz photonic band gap gyrotron amplifier

    E-print Network

    Nanni, Emilio A. (Emilio Alessandro)

    2013-01-01

    This thesis reports the theoretical and experimental investigation of a novel gyrotron traveling-wave-tube (TWT) amplifier at 250 GHz. The gyrotron amplifier designed and tested in this thesis has achieved a peak small ...

  20. Matched wideband low-noise amplifiers for radio astronomy.

    PubMed

    Weinreb, S; Bardin, J; Mani, H; Jones, G

    2009-04-01

    Two packaged low noise amplifiers for the 0.3-4 GHz frequency range are described. The amplifiers can be operated at temperatures of 300-4 K and achieve noise temperatures in the 5 K range (<0.1 dB noise figure) at 15 K physical temperature. One amplifier utilizes commercially available, plastic-packaged SiGe transistors for first and second stages; the second amplifier is identical except it utilizes an experimental chip transistor as the first stage. Both amplifiers use resistive feedback to provide input reflection coefficient S11<-10 dB over a decade bandwidth with gain over 30 dB. The amplifiers can be used as rf amplifiers in very low noise radio astronomy systems or as i.f. amplifiers following superconducting mixers operating in the millimeter and submillimeter frequency range. PMID:19405681

  1. A high bandwidth, low distortion, fully differential amplifier

    E-print Network

    Signoff, David Michael

    2005-01-01

    An amplifier for use in driving an analog to digital converter in an ultra-wideband test system was designed and simulated. The amplifier has differential inputs and outputs and a bandwidth of greater than 500 MHz. According ...

  2. Method of stabilizing flueric vortex valves and vortex amplifiers

    NASA Technical Reports Server (NTRS)

    Erwin, L. R.; Mc Fall, R. H.

    1970-01-01

    Inducing losses in the vortex chamber of vortex valves and vortex amplifiers resolves the problem of unstable operation caused by a sufficiently large positive feedback. Induced losses also reduce pressure gain and throttling range of vortex pressure amplifier.

  3. Design of a variable gain amplifier for an ultrawideband receiver

    E-print Network

    Krishnanji, Sivasankari

    2005-11-01

    A fully differential CMOS variable gain amplifier (VGA) has been designed for an ultra-wideband receiver. The VGA comprises of two variable gain stages followed by a post amplifier stage. The interface between the digital control block...

  4. Tiny biomedical amplifier combines high performance, low power drain

    NASA Technical Reports Server (NTRS)

    Deboo, G. J.

    1965-01-01

    Transistorized, portable, high performance amplifier with low power drain facilitates biomedical studies on mobile subjects. This device, which utilizes a differential input to obtain a common-mode rejection, is used for amplifying electrocardiogram and electromyogram signals.

  5. Extremely low-distortion multi-carrier amplifier-self-adjusting feed-forward (SAFF) amplifier

    Microsoft Academic Search

    Shoichi NARAHASHI; T. Nojima

    1991-01-01

    A newly developed nonlinear distortion compensation circuit is presented for high-frequency power amplifiers (PAs), the self-adjusting feedforward (SAFF). A self-adjusting function utilizing a microprocessor and pilot signals provides both precise and stable distortion compensation performance. One of the most important SAFF applications is to construct a multicarrier transmitting amplifier for mobile communications. A computer analysis is performed to predict the

  6. Resonant control of structural vibration using charge-driven piezoelectric actuators

    Microsoft Academic Search

    S. O. Reza Moheimani; Benjamin J. G. Vautier

    2005-01-01

    Driving piezoelectric actuators by charge, or current rather than voltage is known to significantly reduce the hysteretic nature of these actuators. Although this feature of piezoelectric transducers has been known to the researchers for some time, still voltage amplifiers are being used as the main driving mechanism for piezoelectric devices. This is due to the perceived difficulty in building charge\\/current

  7. Dynamics of high-power erbium-ytterbium fiber amplifiers

    Microsoft Academic Search

    Guillaume Canat; Jean-Claude Mollier; Jean-Pierre Bouzinac; Glenn M. Williams; Brian Cole; Lew Goldberg; Yves Jaouën; Gabor Kulcsar

    2005-01-01

    Dynamic regimes of high-peak-power erbium-ytterbium (Er3+-Yb3+) codoped fiber amplifiers are analyzed for nanosecond-to-microsecond pulses. High-energy pulse generation requires a large-core fiber amplifier to increase energy storage and the threshold of nonlinear effects. A numerical model of large-core Er3+-Yb3+ fiber amplifiers is described. Dynamics of peak powers, amplified spontaneous emission, and population inversion are presented. Influence of radial dependence and reflections

  8. An Ultra-Low-Distortion Transistorized Power Amplifier

    Microsoft Academic Search

    H. M. Kleinman; C. F. Wheatley

    1961-01-01

    The development of a new type of power transistor has made possible the construction of ultra-high-performance audio-frequency amplifiers which can equal the performance of the finest vacuum-tube amplifiers available. The design, construction, and performance characteristics of such an amplifier, using RCA drift-field power transistors, is discussed. The amplifier is capable of providing a power output of 50 watts at less

  9. An amplifier for use with large-area photodiodes

    SciTech Connect

    Dyer, G.R.; Uckan, T. (Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, TN (USA))

    1990-12-01

    We describe a high-gain ({approximately}10{sup 7}) amplifier for use with large-area silicon photodiodes for monitoring the intensity of plasma light from fusion experiments. To achieve the necessary gain without saturating the output signal, the amplifier design incorporates a bootstrap technique and capacitive coupling between amplifier stages. This design eliminates voltage offset at the amplifier output due to detector leakage, while retaining desirable low-frequency response characteristics.

  10. A 28 GHz, 100 mW FET amplifier

    NASA Astrophysics Data System (ADS)

    Clarke, B.; Bradley, J.; Pelletier, M.

    1989-05-01

    The solid state FET (field effect transistor) amplifier developed to drive a traveling wave tube amplifier in an earth station application is described. Two-stage amplifier modules were developed using small signal FETs on 10 mil Duroid substrate and optimized for output power. An output power of 100 mW with 16 dB gain was achieved over the 28.0 to 28.7 GHz frequency band by combining the outputs of two paralleled amplifiers.

  11. Microwave-Carrier Modulation-Demodulation Amplifiers and Logic Circuits

    Microsoft Academic Search

    W. ECKHARDTt; F. STERZERt

    1962-01-01

    Modulation-demodulation (M-D) amplifiers are four-terminal unidirectional amplifiers in which amplitude modulators with conversion gain are followed by demodulators. This paper describes wideband video M-D amplifiers (voltage-gain-bandwidth product = 1.5 Gc), low-noise RF M-D amplifiers (signal frequency = 1.2 Gc, voltage-gain-bandwidth product = 70 Mc, noise figure < 3 db), and ultra-high-speed M-D logic circuits (possible pulse repetition rates of the

  12. Development of Submillimeter SIS Mixers and Broadband HEMT Amplifiers

    NASA Technical Reports Server (NTRS)

    Zmuidzinas, J.

    2004-01-01

    This is the final technical report for NASA grant NAG5-9493. entitled "Development of Submillimeter SIS Mixers and Broadband HEMT Amplifiers". The goal of this project was to develop and demonstrate a new generation of superconducting tunnel junction (SIS) receivers with extremely wide instantaneous (intermediate-frequency, or IF) bandwidths. of order 12 GHz. along with the wideband low-noise microwave HEMT (high electron mobility transistor) amplifiers which follow the SIS mixer. These wideband SIS/HEMT receivers would allow rapid submillimeter wavelength spectral line surveys to be carried out, for instance with the NASA airborne observatory SOFIA. and could potentially be useful for future submillimeter space missions such as SAFIR. In addition, there are potential NASA earth science applications. such as the monitoring of the distribution of chemical species in the stratosphere and troposphere using the limb-sounding technique. The overall goals of this project have been achieved: a broadband 200-300 SIS receiver was designed and constructed, and was demonstrated in the field through a test run at the Caltech Submillimeter Observatory on Mauna Kea. HI. The technical details are described in the appendices. which are primarily conference publications. but Appendix A also includes an unpublished summary of the latest results. The work on the SIS mixer design are described in the conference publications (appendices B and C). The "Supermix" software package that was developed at Caltech and used for the SIS design is also described in two conference papers, but has been substantially revised, debugged. and extended as part of the work completed for this grant. The Supermix package is made available to the community at no charge. The electromagnetic design of a radial waveguide probe similar to the one used in this work is described in a journal publication. Details of the novel fabrication procedure used for producing the SIS devices at JPL are also given in an upcoming journal article. Finally, details on the wideband HEMT amplifier design and noise characterization techniques are described in two publications.

  13. Technical status of SSC RF amplifier and accelerating cavity systems

    Microsoft Academic Search

    J. Ferrell; J. Rogers; P. Coleman; J. Curbow; J. Mynk

    1993-01-01

    An overview of the design status of each RF amplifier system is presented and potential opportunities for industry involvement are identified. Specifically, brief descriptions of the LINAC, LEB, MEB, HEB, and Collider RF Amplifier systems are presented, as well as the LEB and MEB cavities. Status in the LINAC ranges from an RFQ Amplifier being operational at the SSC to

  14. Amplifier circuit operable over a wide temperature range

    Microsoft Academic Search

    Ronald D. Kelly; William L. Cannon

    1979-01-01

    An amplifier circuit having stable performance characteristics over a wide temperature range from approximately 0.degree. C up to as high as approximately 500.degree. C, such as might be encountered in a geothermal borehole. The amplifier utilizes ceramic vacuum tubes connected in directly coupled differential amplifier pairs having a common power supply and a cathode follower output stage. In an alternate

  15. An electro-optical power amplifier and trigger circuit

    Microsoft Academic Search

    J. F. Vize; C. F. Spitzer

    1956-01-01

    If electroluminescent cells and photoconductor cells are placed in optical vicinity, the combination can be used as a power amplifier for electrical signals. Whereas in vacuum tubes control is exerted by an electric field, and in magnetic amplifiers by a magnetic field, this new amplifier type uses light as a control medium. Static power gains up to 40 db have

  16. A High CMRR Instrumentation Amplifier for Biopotential Signal Acquisition 

    E-print Network

    Muhammad Abdullah, Reza

    2012-07-16

    ??????.?..?...21 2-4 Common Mode Gain vs. Percentage Mismatch in Y4??????.?..?...21 2-5 RC Feedback Amplifier Used for EKG Signal Acquisition .......................... 22 2-6 Common Mode Gain vs. Frequency of an RC Feedback Amplifier... Impedance Parameters ..................................................................... 8 1-4 General Requirements of an EKG Amplifier ...................................................... 11 2-1 Typical Requirements of an EKG Signal...

  17. Theoretical and experimental investigation of semiconductor laser amplifiers

    SciTech Connect

    Huang Dexiu; Liu Deming; Zhang Qichao; Fan Chenjun; Li Longqin

    1988-07-01

    Theoretical and experimental studies of both the Fabry-Perot type and the traveling-wave type semiconductor laser amplifiers were performed. The gain characteristics of the semiconductor laser amplifiers were analyzed and the advantages of the quasi-traveling-wave laser amplifiers were discussed.

  18. Orbital performance of communication satellite microwave power amplifiers (MPAs)

    Microsoft Academic Search

    R. Strauss

    1993-01-01

    This paper presents background data on the performance of microwave power amplifiers (MPAs) used as transmitters in currently operating commercial communication satellites. Specifically aspects of two competing MPA types are discussed. These are well known TWTA (travelling wave tube amplifier) and the SSPA (solid state power amplifier). Extensive in-orbit data has been collected from over 2000 MPAs in 1991 and

  19. Novel 1500 nm-band EDFA with discrete Raman amplifier

    Microsoft Academic Search

    E. Ishikawa; M. Nishihara; Y. Sato; C. Ohshima; Y. Sugaya; J. Kumasako

    2001-01-01

    We first demonstrate amplification in EDFA at wavelengths of 1489-1519 nm using a multi-stage configuration of silica-based EDF (erbium doped fiber) and ASE (amplified spontaneous emission) suppressing filters. The Raman\\/EDFA hybrid amplifier realizes a useful S-band optical amplifier with dispersion compensation and low non-linearity.

  20. Noise Characterization of Raman-assisted Fiber Optical Parametric Amplifiers

    E-print Network

    Wai, Ping-kong Alexander

    Noise Characterization of Raman-assisted Fiber Optical Parametric Amplifiers S. H. Wang,1 Lixin Xu, 230026, China Abstract Raman-assisted fiber optical parametric amplifiers with approaching 3-dB noise parametric amplifiers (FOPAs), parametric fluorescence and spontaneous Raman scattering induced by parametric

  1. Characterization of Raman-assisted Fiber Optical Parametric Amplifiers Gain

    E-print Network

    Wai, Ping-kong Alexander

    Characterization of Raman-assisted Fiber Optical Parametric Amplifiers Gain S. H. Wang,1 Lixin Xu,2 of the gain of Raman-assisted fiber optical parametric amplifiers. The model can be used to design amplifiers and oscillators; (190.4380) Four-wave mixing; (190.5650) Raman effect. 1. Introduction Fiber

  2. Designing Raman amplified transmission systems -what's there and how to

    E-print Network

    Park, Namkyoo

    Designing Raman amplified transmission systems - what's there and how to Namkyoo Park, Jonghan Park@plaza.snu.ac.kr, T : +82-2-880-1820, F : +82-2-885-5284). ABSTRACT Transmission systems employing Raman amplifier building block - a unit of a fiber Raman amplifier (FRA), the designer have to struggle with the problems

  3. Analytical study of pulse amplification in silicon Raman amplifiers

    E-print Network

    Analytical study of pulse amplification in silicon Raman amplifiers Ivan D. Rukhlenko,1, Malin the dynamics of silicon Raman amplifiers (SRAs), a numerical approach is generally employed, even though. Jalali, O. Boyraz, V. Raghunathan, D. Dimitropoulos, and P. Koonath, "Silicon Raman amplifiers, lasers

  4. Noise Figure of Silicon Raman Amplifiers Dimitrios Dimitropoulos, 1

    E-print Network

    Jalali. Bahram

    Noise Figure of Silicon Raman Amplifiers 1 Dimitrios Dimitropoulos, 1 Daniel R. Solli , 2 Ozdal calculations show nonlinear absorption significantly degrades the noise figure of silicon Raman amplifiers amplifier. We develop a quantum mechanical model to determine the minimum noise figure of the silicon Raman

  5. Extreme events in fiber based amplifiers Kamal Hammani 1

    E-print Network

    Paris-Sud XI, Université de

    investigate Raman and parametric amplifiers pumped by a partially incoherent field, and we will outline will propose strategies to isolate the rarest events. 2. EXTREME EVENTS IN RAMAN AMPLIFIERS We first investigate a configuration based on a Raman fiber amplifier pumped by a partially incoherent wave. 2

  6. Recent advances in ultra-wideband Raman amplifiers

    Microsoft Academic Search

    S. Namiki; Y. Emori

    2000-01-01

    This talk will review fundamentals of ultra-wideband Raman amplifiers, recent progress of high power pump lasers, and system applications of Raman amplifiers. Pump wavelength determines the gain spectrum of a Raman amplifier. This implies that the gain created by a multi wavelength pumping can have a wideband gain profile, which is approximately described by a linear superposition of each gain

  7. Spectral hole burning measurement thulium-doped fiber amplifiers

    Microsoft Academic Search

    Fabien Roy; Dominique Bayart; Céline Heerdt; André Le Sauze; Pascal Baniel

    2002-01-01

    An accurate technique was implemented to measure spectral hole burning in rare-earth amplifiers at room temperature, showing that thulium-doped fiber amplifiers exhibit hole depths four times lower than those of C-band erbium-doped fiber amplifiers.

  8. An Information Theoretic Approach to Optimal Amplifier Operation

    E-print Network

    Maryland at College Park, University of

    An Information Theoretic Approach to Optimal Amplifier Operation Nicole M. Nelson and Pamela A Park MD, 20742 USA nmnelson,pabshire@umd.edu Abstract-- Amplifier performance can be severely degraded-range operational transconductance amplifiers (OTAs) using the principles of information theory. Frequency transfer

  9. OPTICAL PARAMETRIC AMPLIFIER TEST FOR OPTICAL STOCHASTIC COOLING OF RHIC

    E-print Network

    Brookhaven National Laboratory

    OPTICAL PARAMETRIC AMPLIFIER TEST FOR OPTICAL STOCHASTIC COOLING OF RHIC I. Pavlishin, D. Stolyarov of Optical Parametric Amplifier (OPA) for OSC was suggested by Max Zolotorev [1, 2]. We have tested, amplified and then sent into the kicker undulator. The cooling occurs when the particle from the beam

  10. Signal Conditioning Amplifier and Recorder (SCAmpR)

    NASA Technical Reports Server (NTRS)

    Medelius, Pedro J.; Voska, Ned (Technical Monitor)

    2002-01-01

    The Signal Conditioning Amplifier and Recorder (SCAmpR) system is presented. The topics include: 1) System Description; 2) Universal Signal Conditioning Amplifier (USCA); 3) Advanced Data Acquisition System (ADAS); and 4) Signal Conditioning Amplifier and Recorder (SCAmpR). This paper is presented in viewgraph form.

  11. A 16-ELEMENT REFLECTION GRID AMPLIFIER Frederic Lecuyer1

    E-print Network

    . The emitter current is set by the common-mode emitter resistor. This resistor is bypassed with a capacitorA 16-ELEMENT REFLECTION GRID AMPLIFIER Frederic Lecuyer1 , Robert Swisher1 , Iok-Fai Frank Chio1, OR ABSTRACT We present a 16-element hybrid grid amplifier. This is the first successful grid amplifier to use

  12. PM and AM noise in common base amplifier

    Microsoft Academic Search

    T. I. Boldyreva; V. N. Kuleshov

    1999-01-01

    Theoretical analysis of PM and AM noise introduced by common base (CB) bipolar transistor amplifier and comparison of CB and common emitter (CE) amplifiers are presented. The analysis is based on the approach and the models developed and used in the papers (1997, 1998). Power spectral densities (PSD) of PM and AM noises of CB amplifier (both wideband and 1\\/f

  13. BJT Single Stage Amplifier Circuits ECE 3050 --Analog Electronics

    E-print Network

    Leach Jr.,W. Marshall

    BJT Single Stage Amplifier Circuits ECE 3050 -- Analog Electronics The Common-Emitter Amplifier The common-emitter amplifier is used to obtain a high voltage gain and a high input resis- tance. The circuit r0 e = Rtb + rx 1 + + re r0 = VA + VCE IC Figure 1: (a) Ac signal circuit of the common-emitter

  14. Evaluation and comparison of three IR detectors and three amplifier designs for a new, high-speed IR pyrometer

    SciTech Connect

    J.A. Young, S. Borrora, A.W. Obst, J.R. Payton, A. Seifter

    2005-01-01

    At Los Alamos National Laboratory (LANL), a high-speed, four-wavelength, infrared (IR) pyrometer has been used for surface temperature measurements in shock-physics experiments for several years. The pyrometer uses solid state detectors and a single fiber-optic cable for transmission of light from the target surface to the detectors. This instrument has recently been redesigned for an upcoming experiment at the Nevada Test Site (NTS). Three different IR detectors (two HgCdTe variants as well as the existing InSb chip) were compared for sensitivity, signal-to-noise ratio, and bandwidth. Of major concern was detector amplifier recovery time from overload saturation. In shock physics experiments, a short but very bright precursor frequently accompanies shock breakout (often from trapped air). This precursor can saturate the amplifier and may ''swamp-out'' the signal of interest before the amplifier recovers. With this in mind, we evaluated two new amplifier designs by the Perry Amplifier Company for linearity, signal-to-noise characteristics, gain, and saturation recovery time. This paper describes experimental setup for detector comparison and results obtained. Furthermore, we discuss new amplifier design and suitability for highspeed infrared pyrometry in shock physics experiments.

  15. A Charge-Based Low-Power High-SNR Capacitive Sensing Interface Circuit

    PubMed Central

    Peng, Sheng-Yu; Qureshi, Muhammad S.; Hasler, Paul E.; Basu, Arindam; Degertekin, F. L.

    2008-01-01

    This paper describes a low-power approach to capacitive sensing that achieves a high signal-to-noise ratio. The circuit is composed of a capacitive feedback charge amplifier and a charge adaptation circuit. Without the adaptation circuit, the charge amplifier only consumes 1 ?W to achieve the audio band SNR of 69.34dB. An adaptation scheme using Fowler-Nordheim tunneling and channel hot electron injection mechanisms to stabilize the DC output voltage is demonstrated. This scheme provides a very low frequency pole at 0.2Hz. The measured noise spectrums show that this slow-time scale adaptation does not degrade the circuit performance. The DC path can also be provided by a large feedback resistance without causing extra power consumption. A charge amplifier with a MOS-bipolar pseudo-resistor feedback scheme is interfaced with a capacitive micromachined ultrasonic transducer to demonstrate the feasibility of this approach for ultrasound applications. PMID:18787650

  16. Quantum enhancement of a coherent ladar receiver using phase-sensitive amplification

    E-print Network

    Shapiro, Jeffrey H.

    We demonstrate a balanced-homodyne LADAR receiver employing a phase-sensitive amplifier (PSA) to raise the effective photon detection efficiency (PDE) to nearly 100%. Since typical LADAR receivers suffer from losses in the ...

  17. Direct solar-pumped iodine laser amplifier

    NASA Technical Reports Server (NTRS)

    Han, Kwang S.; Kim, K. H.; Stock, L. V.

    1986-01-01

    In order to evaluate the feasibility of the solar pumped dye laser, the parametric study of a dye laser amplifier pumped by a solar simulator and flashlamp was carried out, and the amplifier gains were measured at various pump beam irradiances on the dye cell. Rhodamine 6G was considered as a candidate for the solar pumped laser because of its good utilization of the solar spectrum and high quantum efficiency. The measurement shows that a solar concentration of 20,000 is required to reach the threshold of the dye. The work to construct a kinetic model algorithm which predicts the output parameter of laser was progressed. The kinetic model was improved such that there is good agreement between the theoretical model and experimental data for the systems defined previously as flashlamp pumped laser oscillator, and the long path length solar pumped laser.

  18. Self-imaging silicon Raman amplifier

    E-print Network

    Raghunathan, V; Renner, H; Rice, R R; Jalali, Bahram; Raghunathan, Varun; Renner, Hagen; Rice, Robert R.

    2006-01-01

    We propose a new type of waveguide optical amplifier. The device consists of collinearly propagating pump and amplified Stokes beams with periodic imaging of the Stokes beam due to the Talbot effect. The application of this device as an Image preamplifier for Mid Wave Infrared (MWIR) remote sensing is discussed and its performance is described. Silicon is the preferred material for this application in MWIR due to its excellent transmission properties, high thermal conductivity, high damage threshold and the mature fabrication technology. In these devices, the Raman amplification process also includes four-wave-mixing between various spatial modes of pump and Stokes signals. This phenomenon is unique to nonlinear interactions in multimode waveguides and places a limit on the maximum achievable gain, beyond which the image begins to distort. Another source of image distortion is the preferential amplification of Stokes modes that have the highest overlap with the pump. These effects introduce a tradeoff between...

  19. Magnetic Amplifier for Power Flow Control

    SciTech Connect

    None

    2012-02-24

    GENI Project: ORNL is developing an electromagnet-based, amplifier-like device that will allow for complete control over the flow of power within the electric grid. To date, complete control of power flow within the grid has been prohibitively expensive. ORNL’s controller could provide a reliable, cost-effective solution to this problem. The team is combining two types of pre-existing technologies to assist in flow control, culminating in a prototype iron-based magnetic amplifier. Ordinarily, such a device would require expensive superconductive wire, but the magnetic iron core of ORNL’s device could serve as a low-cost alternative that is equally adept at regulating power flow.

  20. Theory of amplified dispersive Fourier transformation

    SciTech Connect

    Goda, Keisuke; Solli, Daniel R.; Jalali, Bahram [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Tsia, Kevin K. [Deparment of Electrical and Electronic Engineering, University of Hong Kong, Pokfulam Road (Hong Kong)

    2009-10-15

    Amplified dispersive Fourier transformation (ADFT) is a powerful technique that maps the spectrum of an optical pulse into a time-domain waveform using group-velocity dispersion (GVD) and simultaneously amplifies it in the optical domain. It replaces a diffraction grating and detector array with a dispersive fiber and single photodetector, greatly simplifying the system and, more importantly, enabling ultrafast real-time spectroscopic measurements. Here we present a theory of ADFT by deriving the general equation and spectral resolution for ADFT and studying the evolution of the pulse spectrum into time, the effect of GVD coefficients on ADFT, and the requirement for dispersion. This theory is expected to lend valuable insights into the process and implementation of ADFT.

  1. The impact of nonlinearity on degenerate parametric amplifiers

    NASA Astrophysics Data System (ADS)

    Rhoads, Jeffrey F.; Shaw, Steven W.

    2010-06-01

    This work investigates the effects of system nonlinearities on degenerate parametric amplifiers. A simple, Duffing-type nonlinearity is appended to a representative equation of motion for a mechanical or electromechanical parametric amplifier, and classical perturbation methods are used to characterize the resulting effects on the amplifier's frequency response and performance. Ultimately, the work demonstrates that parametric amplification can be realized in nonlinear, dynamic-range limited systems, such as resonant micro- or nanosystems, but at the expense of performance degradation. Additionally, it is shown that nonlinear amplifiers can be operated above their linear instability threshold but that doing so results in bistable amplified responses.

  2. Enhanced propagation of photon density waves in random amplifying media

    NASA Astrophysics Data System (ADS)

    Renthlei, Lalruatfela; Wanare, Harshawardhan; Ramakrishna, S. Anantha

    2015-04-01

    We demonstrate enhanced wavelike character of diffuse photon density waves (DPDW) in an amplifying random medium. The amplifying nature makes it necessary to choose the wave solution that grows inside the amplifying medium, and has a propagation vector pointing opposite to the growth direction. This results in negative refraction of the DPDW at an absorbing-amplifying random medium interface as well as the possibility of supporting "anti"-surface-like modes at the interface. A slab of an amplifying random medium sandwiched between two absorbing random media supports waveguide resonances that can be utilized to extend the imaging capabilities of DPDW.

  3. Analysis of multipass laser amplifier systems for storage laser media

    SciTech Connect

    Harvey, J.F.

    1980-03-25

    The performance characteristics of single pass and multipass storage laser amplifiers are presented and compared. The effects of the multipass amplifier parameters on the extraction characteristics are examined. For a wide range of conditions the multipass amplifier is found to provide high energy gain and high efficiency simultaneously. This is a significant advantage over the single pass laser amplifier. Finally, three specific storage laser amplifier systems, flashlamp pumped V:MgF/sub 2/, XeF laser pumped Tm:Glass, and photolytically pumped Selenium, are examined. The performance characteristics for each of the three systems are calculated and compared.

  4. Characterization of a Common-Source Amplifier Using Ferroelectric Transistors

    NASA Technical Reports Server (NTRS)

    Hunt, Mitchell; Sayyah, Rana; MacLeond, Todd C.; Ho, Pat D.

    2010-01-01

    This paper presents empirical data that was collected through experiments using a FeFET in the established common-source amplifier circuit. The unique behavior of the FeFET lends itself to interesting and useful operation in this widely used common-source amplifier. The paper examines the effect of using a ferroelectric transistor for the amplifier. It also examines the effects of varying load resistance, biasing, and input voltages on the output signal and gives several examples of the output of the amplifier for a given input. The difference between a commonsource amplifier using a ferroelectric transistor and that using a MOSFET is addressed.

  5. Characterization of a Common-Gate Amplifier Using Ferroelectric Transistors

    NASA Technical Reports Server (NTRS)

    Hunt, Mitchell; Sayyah, Rana; MacLeod, Todd C.; Ho, Fat D.

    2011-01-01

    In this paper, the empirical data collected through experiments performed using a FeFET in the common-gate amplifier circuit is presented. The FeFET common-gate amplifier was characterized by varying all parameters in the circuit, such as load resistance, biasing of the transistor, and input voltages. Due to the polarization of the ferroelectric layer, the particular behavior of the FeFET common-gate amplifier presents interesting results. Furthermore, the differences between a FeFET common-gate amplifier and a MOSFET common-gate amplifier are examined.

  6. Quantifying memory effects in RF power amplifiers

    Microsoft Academic Search

    Hyunchul Ku; Michael D. McKinley; J. Stevenson Kenney

    2002-01-01

    This paper proposes a system-level behavioral model for RF power amplifiers (PAs), which exhibit memory effects, that is based on the parallel Wiener system. The model extraction is performed using two-tone intermodulation distortion (IMD) measurements with different tone frequency spacings and power levels. It is found that by using such a model, more accurate adjacent-channel power-ratio levels may be predicted

  7. RF power amplifier integration in CMOS technology

    Microsoft Academic Search

    Y. J. E. Chen; M. Hamai; D. Heo; A. Sutono; S. Yoo; J. Laskar

    2000-01-01

    This paper explores different levels of integration for CMOS RF power amplifiers, including integration fully on chip, integration with LTCC passive components, and integration with off-chip components. At 1.9 GHz, the fully on-chip integrated CMOS PA can deliver 20 dBm output power with 16% efficiency. Because the LTCC inductors have much higher Q than the on-chip inductors, the CMOS PA

  8. Electrically Tuned RC Oscillator or Amplifier

    Microsoft Academic Search

    Oswald Villard; Frank Holman

    1953-01-01

    Two RC circuits based upon all-pass phase-shift networks are described. They are useful as electronically tunable audio oscillators, selective amplifiers, or bridges. Change of resonant frequency is accomplished by varying amplitude of transmission in one or more circuit branches by means of vacuum-tube modulators. In theory, both circuits may be electronically tuned from zero to infinite frequency, and their feedback-loop

  9. Class-AB\\/F Doherty Power Amplifiers

    Microsoft Academic Search

    Daehyun Kang; Daekyu Yu; Kyoungjoon Min; Jinsung Choi; Myoungsu Jun; Dongsu Kim; Bumman Kim

    2008-01-01

    The class-AB\\/F Doherty power amplifier (PA) adopts the concept of the class-AB\\/F PA to enhance efficiency while satisfying linearity. The third harmonic control circuits of the PA improve the efficiency without deteriorating the linearity, and the Doherty PA improves the linearity further by IM3 cancelation. The class-AB\\/F chips are fabricated by an InGaP\\/GaAs HBT process and combined on a PCB

  10. Fuel supply system with pneumatic amplifier

    SciTech Connect

    Staerzl, R.E.

    1990-02-27

    This patent describes a fuel control system for an internal combustion engine. It comprises: air intake means supplying combustion air to the engine, and fuel supply means supplying fuel to the engine, a venturi in the air intake means producing a pressure drop, a first pressure sensor sensing pressure outside of the venturi, a second pressure sensor sensing the reduced pressure in the venturi, and means pneumatically amplifying the sensed pressure differential.

  11. Modeling of photonic crystal fiber Raman amplifiers

    Microsoft Academic Search

    Michele Bottacini; Federica Poli; Annamaria Cucinotta; Stefano Selleri

    2004-01-01

    An accurate model has been developed to study photonic crystal fiber Raman amplifiers. The proposed approach calculates the Raman gain efficiency starting from the knowledge of the fiber cross-sectional characteristics, i.e., the geometric parameters and the germania concentration in the doped area. The model allows the study of the Raman amplification process in a photonic crystal fiber with any air-hole

  12. Broad band crossed-beam Raman amplifier

    SciTech Connect

    Bobbs, B.L.; Goldstone, J.A.

    1990-05-01

    This patent describes a crossed-beam Raman amplifier. It has an input pump beam and a Stokes seed beam introduced into a Raman cell at wide angles providing a crossed-beam geometry in which the pump beam has pump lines each angle-tuned at a phase matching angle relative to a Stokes seed line, whereby the ratio of amplification to cell length is maximized.

  13. Amplifier/compressor fiber Raman lasers

    SciTech Connect

    Islam, M.N.; Mollenauer, L.F.; Stolen, R.H.; Simpson, J.R.; Shang, H.T.

    1987-10-01

    We show that the chirp from cross-phase modulation (XPM) dominates the operation of fiber Raman lasers (FRL's). Thus a FRL in the anomalous group-velocity regime is best described as a XPM-chirped Raman amplifier followed by a linear fiber compressor. While the output of such a laser is generally a narrow pulse with a broad pedestal, we show both experimentally and by computer simulation that negligible background is achievable.

  14. An Autozeroing Floating-Gate Amplifier

    Microsoft Academic Search

    Paul Hasler; Bradley A. Minch; Chris Diorio

    2001-01-01

    We have developed a bandpass floating-gate amplifier that uses tunneling and pFET hot-electron injection to set its dc operating point adaptively. Because the hot-electron injection is an inherent part of the pFET's behavior, we obtain this adaptation with no additional circuitry. Because the gate currents are small, the circuit exhibits a high-pass characteristic with a cutoff frequency less than 1

  15. A 100-element HBT grid amplifier

    Microsoft Academic Search

    Moonil Kim; Emilio A. Sovero; Jonathan B. Hacker; Michael P. De Lisio; Jung-Chih Chiao; Shi-Jie Li; David R. Gagnon; James J. Rosenberg; David B. Rutledge

    1993-01-01

    A 100-element 10-GHz grid amplifier has been developed. The active devices in the grid are chips with heterojunction-bipolar-transistor (HBT) differential pairs. The metal grid pattern was empirically designed to provide effective coupling between the HBTs and free space. Two independent measurements, one with focusing lenses and the other without, were used to characterize the grid. In each case, the peak

  16. Offset Correction Techniques for Voltage Sense Amplifiers

    Microsoft Academic Search

    S. Groeneveld

    2006-01-01

    This report deals with offset correction techniques for voltage sense amplifiers and is divided\\u000ainto two different parts: 1) mismatch and 2) offset correction techniques. First a literature\\u000astudy is done on the subject mismatch with specially focus on the future. Mismatch of a\\u000atransistor is determined by the mismatch factors ?VT and ?? which are depend strongly on the

  17. QUANTUM ACTIVATION IN THE JOSEPHSON BIFURCATION AMPLIFIER

    E-print Network

    Fominov, Yakov

    T >> h #12;AC CURRENT BIAS: NON-LINEAR INDUCTOR ( ) sin( )RFI t i t= 2 4 0 0( ) 1 ... 2 12 U I (minimal backaction) sin( )RFi t sin( )RFi t + 0 50Z R= = #12;NATURE'S BIFURCATION AMPLIFIER #12;THE ??? VDC(nV) 1/Q Q=pRC sin( )RFi t sin( )RFi t + P ~ 0.1 fW #12;RF PHASE DIAGRAM: 4.7 GHz #12;START

  18. Radiographic amplifier screens: Fabrication process and characteristics

    NASA Technical Reports Server (NTRS)

    Szepesi, Z. P.

    1977-01-01

    The fabrication process and transfer characteristics for solid state radiographic image transducers (radiographic amplifier screens) is described. These screens were developed for use in real time nondestructive evaluation procedures that require large format radiographic images with contrast and resolution capabilities unavailable with conventional fluoroscopic screens. This work was directed toward screens usable for inmotion, on-line radiographic inspection by means of closed circuit television.

  19. Coplanar waveguide radio frequency ferromagnetic parametric amplifier

    Microsoft Academic Search

    Mingqiang Bao; Alexander Khitun; Yina Wu; Joo-Young Lee; Kang L. Wang; Ajey P. Jacob

    2008-01-01

    In this letter, we report a coplanar waveguide ferromagnetic parametric amplifier fabricated on a ferromagnetic Permalloy thin film. It shows a power gain of 4 dB at 1.15 GHz when the pump power is 11.1 dBm at the pump frequency of 2.30 GHz under the bias field of 13 Oe. This prototype ferromagnetic device can be integrated with the complementary

  20. Common-Emitter Transistor Video Amplifiers

    Microsoft Academic Search

    Georg Bruun

    1956-01-01

    A design procedure and theory are given for the common-emitter transistor video amplifier with and without a feedback resistor in the emitter lead. In the analysis a junction transistor of the alloy type is represented by the Johnson-Giacoletto hybrid-pi equivalent circuit for the common-emitter transistor. The design theory accounts for the most significant part of the bilateralness of the transistor