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1

Current mode charge sensitive amplifying technique providing noise performance independent of the radiation detector capacitance  

Microsoft Academic Search

Alternative current mode charge sensitive amplifier (CSA) topology and related methodology for use as pre-amplification block in radiation detection read out front end IC systems is proposed. It is based on the use of a suitably configured current conveyor architecture providing advantageous noise performance characteristics in comparison to the traditionally used CSA structures. In the proposed architecture the noise at

Thomas Noulis; Stylianos Siskos; Gerard Sarrabayrouse; Laurent Bary

2009-01-01

2

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

Microsoft Academic Search

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

Mohammad Beikahmadi; Shahriar Mirabbasi

2011-01-01

3

Spectroscopic performances of the GERDA cryogenic Charge Sensitive Amplifier based on JFET-CMOS ASIC, coupled to germanium detectors  

Microsoft Academic Search

In the GERDA (GERmanium Detector Array) double-beta-decay experiment, it is planned to operate in liquid Argon (LAr) germanium detectors, organized in three fold strings. In this application the use of cryogenic front-end (FE) electronics is mandatory. Two versions of Charge Sensitive Amplifier (CSA), namely a 1-channel (1-ch) and a 3-channel (3-ch), based on JFET-CMOS circuits, have been realized and tested.

A. D'Andragora; C. M. Cattadori; A. di Vacri; M. Junker; L. Pandola; A. Pullia; S. Riboldi; F. Zocca; M. B. Heider; D. Budjas; J. Kiko; S. Schonert; K. Gusev; B. Majorovits

2009-01-01

4

High sensitivity amplifier/discriminator for PWC's  

SciTech Connect

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.

Hansen, S.

1983-01-01

5

Electrostatic discharge measurement and simulation of a charged power amplifier board  

Microsoft Academic Search

Various RF devices are sensitive to electrostatic discharges. However, current standard test models are lacking in accurately describing the discharge of the printed wiring board itself. This paper outlines a test method for the charged board model (CBM). The CBM event is then studied with 3-D electromagnetic simulations and measurements on a power amplifier test board. The results indicate that

Tuomas Reinvuo; Timo Tarvainen; Toni Viheriäkoski; Pasi Tamminen

2009-01-01

6

A 16-channel continuous charge amplifier with sparse readout  

Microsoft Academic Search

A low-noise low-power 16-channel preamplifier\\/shaper IC designed at the Rutherford Appleton Laboratory (RAL) in 1.5 ?m CMOS is described and the results obtained from the testing of the manufactured IC are presented. The IC was designed for the readout of the photodiodes which detect energy deposits in CsI scintillation bars. Each channel amplifies the input charge from a photodiode and

M. L Prydderch; P. Seller

1996-01-01

7

Electron beam charge state amplifier (EBQA)--a conceptual evaluation.  

SciTech Connect

A concept is presented for stripping low-energy, radioactive ions from 1+ to higher charge states. Referred to as an Electron Beam Charge State Amplifier (EBQA), this device accepts a continuous beam of singly-charged, radioactive ions and passes them through a high-density electron beam confined by a solenoidal magnetic field. Singly-charged ions may be extracted from standard Isotope-Separator-Online (ISOL) sources. An EBQA is potentially useful for increasing the charge state of ions prior to injection into post-acceleration stages at ISOL radioactive beam facilities. The stripping efficiency from q=1+ to 2+ ({eta}{sub 12}) is evaluated as a function of electron beam radius at constant current with solenoid field, injected ion energy, and ion beam emittance used as parameters. Assuming a 5 keV, 1 A electron beam, {eta}{sub 12} = 0.38 for 0.1 keV, {sup 132}Xe ions passing through an 8 Tesla solenoid, 1 m in length. Multi-pass configurations to achieve 3+ or 4+ charge states are also conceivable. The calculated efficiencies depend inversely on the initial ion beam emittances. The use of a helium-buffer-gas, ion-guide stage to improve the brightness of the 1+ beams [1] may enhance the performance of an EBQA.

Dooling, J. C.

1998-10-12

8

A 16-channel continuous charge amplifier with sparse readout  

NASA Astrophysics Data System (ADS)

A low-noise low-power 16-channel preamplifier/shaper IC designed at the Rutherford Appleton Laboratory (RAL) in 1.5 ?m CMOS is described and the results obtained from the testing of the manufactured IC are presented. The IC was designed for the readout of the photodiodes which detect energy deposits in CsI scintillation bars. Each channel amplifies the input charge from a photodiode and shapes it with a 5 ?s time constant (a requirement of the detectors). The peak of the shaped signal is held by a peak-hold amplifier and stored onto a holding capacitor for readout. Each channel includes its own comparator used to identify data for readout. A Data Ready flag is output when any of the channel comparators switches, indicating a ``Hit'', and the peak voltage, along with digital addresses of the ``Hit'' channels, are read out. Two readout modes are available, one allows only those channels with ``Hit'' comparators to be read out, while the other allows all 16 channels to be sampled simultaneously and read out, regardless of the state of the comparators. In each case analogue data is read out in series. A channel noise of 330 electrons ENC RMS plus 6 electrons/pF of detector capacitance has been achieved using 8 mW of power per channel with a 5 V supply. Pulse height distributions for the selected sources detected using a prototype system will be presented along with a brief description of the system.

Prydderch, M. L.; Seller, P.

1996-10-01

9

Mode structure of a noiseless phase-sensitive image amplifier  

NASA Astrophysics Data System (ADS)

Optical parametric amplifiers (OPAs) configured as phase-sensitive amplifiers (PSAs) can be used for noiseless optical image amplification, generation of non-classical states of light, and, in particular, for multimode squeezed light generation. For all these applications and for effective use of the quantum properties of the multimode PSA, we need to know its independently squeezed (or amplified) eigenmodes. First we present the quantum theory of a spatially multimode traveling-wave PSA pumped by a high-power pump beam with arbitrary spatial profile. To quantitatively identify the Green's function of the PSA, we have developed a semi-analytical coupled-mode-theory of the PSA using 2D Hermite-Gaussian mode expansions of the signal- and pump-beam spatial distributions. By using Green's functions of the classical OPA, we calculate the normally ordered quadrature correlators at its output, which provide complete quantum description of the phase-sensitive OPA and enable determination of its independently squeezed eigenmodes. We find the number of the supported eigenmodes and their shapes for a spatially broadband frequency-degenerate optical parametric amplifier with elliptical Gaussian pump. We conclude by discussing our recent extensions of the coupled-mode-theory to study higher-order pump modes, compact representation of the PSA eigenmodes (especially convenient for experiments), and effect of non-zero phase mismatch on the PSA eigenmodes. We expect that the results from our model can be used for optimum mode matching in phase-sensitive image amplification and multimode squeezing generation.

Annamalai, Muthiah

10

Localization of the Cochlear Amplifier in Living Sensitive Ears  

PubMed Central

Background To detect soft sounds, the mammalian cochlea increases its sensitivity by amplifying incoming sounds up to one thousand times. Although the cochlear amplifier is thought to be a local cellular process at an area basal to the response peak on the spiral basilar membrane, its location has not been demonstrated experimentally. Methodology and Principal Findings Using a sensitive laser interferometer to measure sub-nanometer vibrations at two locations along the basilar membrane in sensitive gerbil cochleae, here we show that the cochlea can boost soft sound-induced vibrations as much as 50 dB/mm at an area proximal to the response peak on the basilar membrane. The observed amplification works maximally at low sound levels and at frequencies immediately below the peak-response frequency of the measured apical location. The amplification decreases more than 65 dB/mm as sound levels increases. Conclusions and Significance We conclude that the cochlea amplifier resides at a small longitudinal region basal to the response peak in the sensitive cochlea. These data provides critical information for advancing our knowledge on cochlear mechanisms responsible for the remarkable hearing sensitivity, frequency selectivity and dynamic range.

Ren, Tianying; He, Wenxuan; Porsov, Edward

2011-01-01

11

Transimpedance Amplifier for High Sensitivity Current Measurements on Nanodevices  

Microsoft Academic Search

The paper presents a very high sensitivity transimpedance amplifier in standard CMOS 0.35 mum technology suited for sensing current signals from molecular and nanodevices systems. The circuit, based on an integrator followed by a differentiator configuration, features i) a low-noise time-continuous feedback loop to cope with possible standing currents from the device under test as high as few tens of

Giorgio Ferrari; Fabio Gozzini; Alessandro Molari; Marco Sampietro

2009-01-01

12

Feedback stability of charge amplifiers with continuous reset through forward-biased diode junctions  

SciTech Connect

A low noise charge sensitive amplifier that does not require a feedback resistor nor an additional reset device has recently been proposed and successfully tested in several spectroscopy systems. The discharge of the leakage and signal current from the detector is performed continuously through the forward-biased gate to channel junction of the input JFET or, in general, through a diode shunting the preamplifier input. Up to now this forward-biased FET charge amplifier (FBFA) has been used only with detectors having currents limited to a few tens of pA. Recent applications of the FBFA for larger area detectors operating at room temperature with leakage current up to few nA reveals that the original feedback configuration of the FBFA is no longer stable and can show low frequency oscillations. In this work the double feedback loop of the FBFA and its stability is analyzed in detail, and a solution to the mentioned problem is found. The acceptable limit of the input current value in the original configuration of the amplifier is analytically determined, and a new configuration of the singularities of the loop gain, which guarantees stability of the FBFA response at higher input current, is proposed. Experimental tests are presented that show the critical condition of the original FBFA configuration and verify the feasibly of the new proposed solution.

Fasoli, L.; Fiorini, C.; Bertuccio, G. [Politecnico di Milano (Italy). Dipt. di Elettronica e Informazione

1996-08-01

13

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

Microsoft Academic Search

A Charge Recycling Sense Amplifier Based Logic is pre- sented. This logic is derived from the Sense Amplifier Based Logic, which is a logic style with signal independ- ent power consumption. It has been proven previously to protect security devices such as Smart Cards against power attacks. Experimental results show that the use of advanced circuit techniques, which enable charge

Kris Tiri; Ingrid Verbauwhede

14

Design and production of a new surface mount charge-integrating amplifier for CDF  

SciTech Connect

We present our experiences in designing and producing 26,000 new charge-integrating amplifiers for CDF, using surface-mount components. The new amplifiers were needed to instrument 920 new 24-channel CDF RABBIT boards, which are replacing an older design rendered obsolete by increases in the collision rate. Important design considerations were frequency response, physical size and cost. 5 refs.

Nelson, C.; Drake, G.

1991-01-01

15

Design and production of a new surface mount charge-integrating amplifier for CDF  

SciTech Connect

We present our experiences in designing and producing 26,000 new charge-integrating amplifiers for CDF, using surface-mount components. The new amplifiers were needed to instrument 920 new 24-channel CDF RABBIT boards, which are replacing an older design rendered obsolete by increases in the collision rate. Important design considerations were frequency response, physical size and cost. 5 refs.

Nelson, C.; Drake, G.

1991-12-31

16

Wide bandwidth transimpedance amplifier for extremely high sensitivity continuous measurements.  

PubMed

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

Ferrari, Giorgio; Sampietro, Marco

2007-09-01

17

Design of a charge sensitive preamplifier on high resistivity silicon  

SciTech Connect

A low noise, fast charge sensitive preamplifier was designed on high resistivity, detector grade silicon. It is built at the surface of a fully depleted region of n-type silicon. This allows the preamplifier to be placed very close to a detector anode. The preamplifier uses the classical input cascode configuration with a capacitor and a high value resistor in the feedback loop. The output stage of the preamplifier can drive a load up to 20rhoF. The power dissipation of the preamplifier is 13mW. The amplifying elements are ''Single Sided Gate JFETs'' developed especially for this application. Preamplifiers connected to a low capacitance anode of a drift type detector should achieve a rise time of 20ns and have an equivalent noise charge (ENC), after a suitable shaping, of less than 50 electrons. This performance translates to a position resolution better than 3..mu..m for silicon drift detectors.

Radeka, V.; Rehak, P.; Rescia, S.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Struder, L.; Kemmer, J.

1988-02-01

18

Design of a charge sensitive preamplifier on high resistivity silicon  

SciTech Connect

A low noise, fast charge sensitive preamplifier was designed on high resistivity, detector grade silicon. It is built at the surface of a fully depleted region of n-type silicon. This allows the preamplifier to be placed very close to a detector anode. The preamplifier uses the classical input cascode configuration with a capacitor and a high value resistor in the feedback loop. The output stage of the preamplifier can drive a load up to 20pF. The power dissipation of the preamplifier is 13mW. The amplifying elements are ''Single Sided Gate JFETs'' developed especially for this application. Preamplifiers connected to a low capacitance anode of a drift type detector should achieve a rise time of 20ns and have an equivalent noise charge (ENC), after a suitable shaping, of less than 50 electrons. This performance translates to a position resolution better than 3..mu..m for silicon drift detectors. 6 refs., 9 figs.

Radeka, V.; Rehak, P.; Rescia, S.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Strueder, L.; Kemmer, J.

1987-01-01

19

Design and production of a new surface mount charge-integrating amplifier for CDF  

Microsoft Academic Search

The authors present their experiences in designing and producing 26000 new charge-integration amplifiers for the Collision Detector Facility (CDF), using surface-mount components. The new amplifiers were needed to instrument 920 new 24-channel CDF RABBIT boards, which are replacing an older design rendered obsolete by increases in the collision rate. Important design considerations were frequency response, physical size, and cost. Compared

C. Nelson; G. Drake

1991-01-01

20

Spectroscopy charge amplifier for detectors with integrated front-end FET  

SciTech Connect

A charge amplifier, especially designed for FET integrated on silicon radiation detectors, is presented. The circuit is based on the forward biased FET amplifier configuration, which does not require the feedback resistor nor additional devices for resetting. The severe constraints on the preamplifier design, imposed by the low transconductance of small size integrated FET`s, are analyzed as far as loop-gain, bandwidth, and noise are concerned. A circuit topology which satisfies all the requirements even at relative fast shaping time (1 {micro}s) is proposed and experimentally tested.

Bertuccio, G.; Fasoli, L.; Fiorini, C.; Sampietro, M. [Politecnico di Milano (Italy). Dipartimento di Elettronica e Informazione

1995-08-01

21

Longitudinal space charge amplifier driven by a laser-plasma accelerator  

NASA Astrophysics Data System (ADS)

A longitudinal space charge amplifier (LSCA), operating in VUV anmd soft x-ray regime, was recently proposed. Such an amplifier consists of a few amplification cascades (focusing channel and chicane) and a short radiator undulator in the end. The amplification mechanism is broadband and robust, it is practically insensitive to energy chirp and orbit jitter. Therefore, an LSCA can be considered as an alternative to a SASE FEL in the case of using laser-plasma accelerators as drivers of light sources. In this report we study generation of VUV radiation (below 100 nm) in an LSCA driven by a laser-plasma accelerator with the energy of 300 MeV.

Dohlus, Martin; Schneidmiller, Evgeny; Yurkov, Mikhail V.; Henning, Christoph; Grüner, Florian J.

2013-05-01

22

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

NASA Astrophysics Data System (ADS)

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

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

23

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

NASA Astrophysics Data System (ADS)

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

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

1988-10-01

24

Intense space-charge beam physics relevant to relativistic klystron amplifiers  

Microsoft Academic Search

In this paper, we examine intense space-charge beam physics that is relevant to beam bunching and extraction in a mildly relativistic klystron amplifier, and give numerical examples for a 5 kA, 500 keV electron beam in a 1.3 GHz structure. Much of the peculiar beam physics in these types of devices results from the partitioning of beam energy into kinetic

B. E. Carlsten; R. J. Faehl; M. V. Fazio; W. B. Haynes; R. M. Stringfield

1994-01-01

25

Cyclodextrin carriers of positively charged porphyrin sensitizers.  

PubMed

The cationic sensitizer 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP) forms supramolecular complexes with native, per-methylated, sulfonated and dimethyl-sulfonated cyclodextrins (CDs). Binding interactions were proved by NMR, mass spectra, capillary zone electrophoresis, UV-Vis and fluorescence spectroscopy. The 2D-NMR experiments on native CDs indicate that the interaction of TMPyP with the external CD surface is the dominant binding mode. The high binding affinity of TMPyP towards sulfonated CDs is due to electrostatic interactions. Binding is accompanied by an increase of the TMPyP basicity. Whereas betaCD does not affect the lifetime of the TMPyP triplet states, binding with sulfonated CDs causes the protonation of the TMPyP triplet states even in neutral solution. The diprotonated anionic sensitizer 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPSH(2)(2+)) forms host-guest complexes with native betaCD and gammaCD, similarly as in its non-protonated state. The positive charge of pyrrole nitrogen atoms does not significantly influence the mode of the interaction. In contrast to TMPyP, the lifetimes of the triplet states of bound TPPSH(2)(2+) to native CDs increase. PMID:19707685

Mosinger, Jirí; Slavetínská, Lenka; Lang, Kamil; Coufal, Pavel; Kubát, Pavel

2009-07-20

26

Superoxide dismutase amplifies organismal sensitivity to ionizing radiation  

SciTech Connect

Although increased superoxide dismutase (SOD) activity is often associated with enhanced resistance of cells and organisms to oxidant challenges, few direct tests of the antioxidant importance of this enzyme have been carried out. To assess the importance of SOD in defending against gamma-radiation, we employed Escherichia coli with deficient, normal, and super-normal enzyme activities. Surprisingly, the radiation sensitivity of E. coli actually increases as bacterial SOD activity increases. Elevated intracellular SOD activity sensitizes E. coli to radiation-induced mortality, whereas SOD-deficient bacteria show normal or decreased radiosensitivity. Toxic effects of activated oxygen species are involved in this phenomenon; bacterial SOD activity has no effect on radiation sensitivity under anaerobic conditions or on the lethality of other, non-oxygen-dependent, toxins such as ultraviolet radiation.

Scott, M.D.; Meshnick, S.R.; Eaton, J.W.

1989-02-15

27

Detector embedded device for continuous reset of charge amplifiers: choice between bipolar and MOS transistor  

NASA Astrophysics Data System (ADS)

This work discusses the criteria for the choice of the reset device in a charge amplifier whose front-end is integrated on high-resolution semiconductor detectors. The performances achievable using a bipolar or a MOS transistor as reset device are compared in terms of the linearity of the response and of the added noise as a function of the detector leakage current. The additional constraints in term of available technology and layout compatibility show the advantages of MOS transistors operated in sub-threshold mode.

Guazzoni, C.; Sampietro, M.; Fazzi, A.

2000-04-01

28

Sensitivity of random amplified polymorphic DNA analysis to detect genetic change in sugarcane during tissue culture  

Microsoft Academic Search

Random amplified polymorphic DNA (RAPD) analysis using 10-mer oligonucleotide primers efficiently differentiated sugarcane cultivars and proved suitable for detecting gross genetic change such as that which can occur in sugarcane subjected to prolonged tissue culture, for example in protoplast-derived callus. However, RAPD analysis was not sufficiently sensitive to detect smaller genetic changes that occur during sugarcane genetic transformation. The length

P. W. J. Taylor; J. R. Geijskes; H.-L. Ko; T. A. Fraser; R. J. Henry; R. G. Birch

1995-01-01

29

Highly sensitive immunoassay of carcinoembryonic antigen by capillary electrophoresis with gold nanoparticles amplified chemiluminescence detection.  

PubMed

A noncompetitive immunoassay based on gold nanoparticles (AuNPs) amplified capillary electrophoresis (CE) chemiluminescence (CL) detection was developed for the determination of carcinoembryonic antigen (CEA). In this method, citrate-modified AuNPs were conjugated with horseradish peroxidase (HRP) labeled CEA antibody (Ab*), and incubated with limited amount of CEA antigen. CEA-Ab*-AuNPs complex and excess of Ab*-AuNPs were then separated and quantified by CE with CL detection. Highly sensitive CL detection was achieved by means of p-iodophenol (PIP) enhanced luminol-H2O2-HPR CL reaction and AuNPs amplified. Under the optimal conditions, the CE assay was accomplished within 5min. The linear range for CEA detection was 0.05-20ng/mL with a detection limit of 0.034ng/mL (signal/noise=3), which is three orders magnitude lower than that of without AuNPs amplified. The current method was successfully applied for the quantification of CEA in human serum samples. It was demonstrated that the current CE-CL AuNPs amplified noncompetitive immunoassay was sensitive and highly selective. It may serve as a tool for clinical analysis of CEA to assist in the diagnosis of cancer. PMID:23422894

Jiang, Jing; Zhao, Shulin; Huang, Yong; Qin, Guoxin; Ye, Fanggui

2013-01-23

30

The design of charge-sensitive preamplifier with differential JFET input  

NASA Astrophysics Data System (ADS)

In the highly sensitive detection field, charge-sensitive amplifier is widely used in the preamplifier of detectors, however, the high voltage applied to these detectors (such as CZT nuclear detector) often make serious noise, which may influence the sensitivity of the detector. Despite the traditional passive filter circuit to eliminate the noise of the power, but if the power supply accuracy isn't high enough and the passive circuit eliminate the power supply noise is incomplete. The noise still may affect the performance of the final system. According to the need of nuclear detection and photoelectric detection, a kind of differential JFET charge-sensitive preamplifier is proposed in this paper, which eliminates the power-supply noise and Johnson noise of bias resistance. First, theoretical analysis of the traditional JFET circuit is proved and simulation of the JFET circuit is performed with ORCAD software, which prove that power-supply noise effect the preamplifier. Next, simulation of the innovative circuit is performed with ORCAD software. Finally, the fabricated circuit board is tested with avalanche photo diode (APD). It is shown that the charge-sensitive preamplifier with differential JFET input can significantly eliminate the power-supply noise and Johnson noise of resistance (both low frequency and high frequency) and realize a high sensitivity.

Xiao, Hai-jun; Zhang, Liu-qiang; Xiao, Sha-li; Li, Xian-cang; Huang, Zhen-hua

2013-09-01

31

Charge sensitivity analysis in force-field-atom resolution  

Microsoft Academic Search

Charge sensitivity analysis (CSA) was extended to AMBER force-field resolution. The effective electronegativity and hardness\\u000a data were found using evolutionary algorithms. Four model hardness matrices based on the classical electrostatic, Mataga–Nishimoto,\\u000a Ohno, and Louwen–Vogt interpolation formulae were considered. Mulliken population analysis and electrostatically derived charges\\u000a (CHELPG) were taken into account. It was demonstrated that the Ohno interpolation formula gives the

Anna Stachowicz; Anna Styrcz; Jacek Korchowiec

32

A fully integrated, monolithic, cryogenic charge sensitive preamplifier using N-channel JFETs and polysilicon resistors  

SciTech Connect

In this paper, an integrated charge preamplifier to be used with small (10--30 mm[sup 2]) Si(Li) and Ge(Li) X-ray detectors is described. The preamplifier is designed to operate at cryogenic temperatures ([approximately]100 K to 160 K) for the best performance. An N-channel JFET process technology for integrated charge sensitive preamplifiers has been developed. The process integrates multiple pinch-off voltage JFETs fabricated in an n-type epitaxial layer on a low resistivity p-type substrate. The process also incorporates polysilicon resistors integrated on the same die as the JFETs. The optimized polysilicon resistors exhibit 1/f noise nearly as good as metal film resistors at the same current. Results for integrated amplifier are discussed.

Jung, T.S.; Guckel, H.; Seefeldt, J.; Ott, G.; Ahn, Y.C. (Univ. of Wisconsin, Madison, WI (United States))

1994-08-01

33

Pulse Propagation in Nonlinear Optical Fibers Using Phase-Sensitive Amplifiers.  

NASA Astrophysics Data System (ADS)

A mathematical model for pulse propagation in a nonlinear fiber-optic communications line is presented where linear loss in the fiber is balanced by a chain of periodically-spaced, phase-sensitive amplifiers (PSAs). A multiple scale analysis is employed to average over the strong, rapidly-varying and periodic perturbations to the governing nonlinear Schrodinger equation (NLS). The analysis indicates that the averaged evolution is governed by a fourth-order nonlinear diffusion equation which evolves on a length scale much greater than that of the typical soliton period. In a particular limit, stable steady-state hyperbolic secant solutions of the averaged equation are analytically found to exist provided a minimum amount of overamplification is supplied. Further, arbitrary initial conditions within a wide stability region exponentially decay onto the steady -state. Outside of this analytic regime, extensive numerical simulations indicate that soliton-like steady-states exist and act as exponential attractors for a wide region of parameter space. These simulations also show that the averaged evolution is quite accurate in modeling the full NLS with loss and phase-sensitive gain. The bifurcation structure of the fourth-order equation is explored. A sub-critical bifurcation from the trivial solution is found to occur for a specific overamplification value. Further, a limit point, or fold, is also found which connects the stable branch of solutions with the unstable branch from the subcritical bifurcation. The bifurcation structure can be further explored in parameter space with the use of AUTO which is capable of tracking steady-state solutions for a wide range of parameters. For larger amplifier spacings, a small dispersive radiation field is generated from the periodic forcing of the loss and gain. The NLS with variably-spaced PSAs is then considered in an effort to reduce the radiation field. Numerical results indicate that the dispersive field is effectively attenuated depending upon the variability and distribution of the amplifiers.

Kutz, Jose Nathan

34

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

NASA Astrophysics Data System (ADS)

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

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

1999-07-01

35

Charge-sensitive infrared phototransistors with integrated plasmonic photocouplers  

NASA Astrophysics Data System (ADS)

A plasmonic coupler, which consists of periodic metal gratings and a tapered waveguide, is integrated to a charge-sensitive infrared phototransistor (CSIP) for 45 µm wavelength radiation. The period and height of the gratings are about 42 µm and 4 µm, respectively. The gratings convert normally incident radiation into a surface wave, which is converged to the active region of the CSIP through the tapered waveguide. Both rise rate and signal amplitude become larger, due to the presence of the plasmonic coupler.

Wang, Zhihai; Ishibashi, Koji; Komiyama, S.; Patrashin, Mikhail; Hosako, Iwao

2013-04-01

36

A novel charge sensitive preamplifier without the feedback resistor  

SciTech Connect

A novel charge sensitive preamplifier 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 first JFET which works with its gate to source junction slightly forward biased. The DC stabilization of the preamplifier is accomplished by an additional feedback loop, which permits to equalize the current flowing through the forward baised gate to source junction and the current coming from the detector. An equivalent noise charge of less than 20 electrons r.m.s. has been measured at room temperature by using an input JFET with a transconductance to gate capacitance ratio of 4 mS/5.4 pF.

Bertuccio, G. (Politecnico di Milano, Milan (Italy). Dipt. di Elettronica e Informazione); Rehak, P.; Xi, D. (Brookhaven National Lab., Upton, NY (United States))

1992-01-01

37

A novel charge sensitive preamplifier without the feedback resistor  

SciTech Connect

A novel charge sensitive preamplifier 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 first JFET which works with its gate to source junction slightly forward biased. The DC stabilization of the preamplifier is accomplished by an additional feedback loop, which permits to equalize the current flowing through the forward baised gate to source junction and the current coming from the detector. An equivalent noise charge of less than 20 electrons r.m.s. has been measured at room temperature by using an input JFET with a transconductance to gate capacitance ratio of 4 mS/5.4 pF.

Bertuccio, G. [Politecnico di Milano, Milan (Italy). Dipt. di Elettronica e Informazione; Rehak, P.; Xi, D. [Brookhaven National Lab., Upton, NY (United States)

1992-07-01

38

Electrical graphene aptasensor for ultra-sensitive detection of anthrax toxin with amplified signal transduction.  

PubMed

Detection of the anthrax toxin, the protective antigen (PA), at the attomolar (aM) level is demonstrated by an electrical aptamer sensor based on a chemically derived graphene field-effect transistor (FET) platform. Higher affinity of the aptamer probes to PA in the aptamer-immobilized FET enables significant improvements in the limit of detection (LOD), dynamic range, and sensitivity compared to the antibody-immobilized FET. Transduction signal enhancement in the aptamer FET due to an increase in captured PA molecules results in a larger 30 mV/decade shift in the charge neutrality point (Vg,min ) as a sensitivity parameter, with the dynamic range of the PA concentration between 12 aM (LOD) and 120 fM. An additional signal enhancement is obtained by the secondary aptamer-conjugated gold nanoparticles (AuNPs-aptamer), which have a sandwich structure of aptamer/PA/aptamer-AuNPs, induce an increase in charge-doping in the graphene channel, resulting in a reduction of the LOD to 1.2 aM with a three-fold increase in the Vg,min shift. PMID:23589198

Kim, Duck-Jin; Park, Hae-Chul; Sohn, Il Yung; Jung, Jin-Heak; Yoon, Ok Ja; Park, Joon-Shik; Yoon, Moon-Young; Lee, Nae-Eung

2013-04-16

39

DNA methylation changes detected by methylation-sensitive amplified polymorphism in two contrasting rice genotypes under salt stress  

Microsoft Academic Search

DNA methylation, one of the most important epigenetic phenomena, plays a vital role in tuning gene expression during plant development as well as in response to environmental stimuli. In the present study, a methylation-sensitive amplified polymorphism (MSAP) analysis was performed to profile DNA methylation changes in two contrasting rice genotypes under salt stress. Consistent with visibly different phenotypes in response

Wensheng Wang; Xiuqin Zhao; Yajiao Pan; Linghua Zhu; Binying Fu; Zhikang Li

2011-01-01

40

Global sensitivity analyses of coherent beam combining of fiber amplifier arrays by the use of numerical space filling designs  

Microsoft Academic Search

We perform sensitivity analyses on two different array configurations of coherently combined fiber amplifiers to study the impact of residual phase errors onto the combining efficiency. The arrays studied are: a square of 16 fibers and a hexagon of 19 fibers. For the hexagon, two different shaped wavefronts are studied. In this method a global analysisis performed: we modify simultaneously

Adrian Azarian; Olivier Vasseur; Baya Bennaï; Laurent Lombard; Guillaume Canat; Véronique Jolivet; Yves Jaouën; Pierre Bourdon

2011-01-01

41

Determination of tumor necrosis factor-? (TNF-?) in serum by a highly sensitive enzyme amplified lanthanide luminescence immunoassay  

Microsoft Academic Search

Objectives: To develop a highly sensitive enzyme amplified lanthanide luminescence (EALL) immunoassay for tumor necrosis factor-? (TNF-?).Methods: The method is based on the use of two monoclonal antibodies against TNF-?, one “capture” antibody and one labeled with biotin, in a “sandwich type” assay format. Alkaline phosphatase (ALP) conjugated to an antibiotin-polyclonal antibody is used as the enzyme label. ALP cleaves

Constantinos Petrovas; Spiros M Daskas; Evriklia S Lianidou

1999-01-01

42

Rapid and sensitive microbial analysis by capillary isotachophoresis with continuous electrokinetic injection under field amplified conditions.  

PubMed

A highly sensitive capillary isotachophoresis method with LIF detection for microbial analysis was developed. This allowed the reliable analysis of Escherichia coli bacteria with a LOD of 14 cells in a sample volume of 100 ?L, or 1.35 × 10(2) cell/mL, which is 47 times lower than reported by CE-LIF and 148 times lower than CE-UV with on-line concentration. A leading electrolyte of 50 mM Tris-HCl was used while the cells were diluted in 5 mM Tris HEPES as the terminator. To facilitate detection, cells were stained with the universal nucleic acid fluorophore SYTO 9. Continuous electrokinetic injection of the cells from the terminator under field amplified conditions concentrated cells into a single peak at the leader/terminator boundary allowing quantitation by measurement of peak height. The method was applied to water collected from two local streams, with only filtration through a 5-?m syringe filter to remove large particulate matter followed by a ten times dilution in terminator, with total analysis time approximately 40 min. The detected cell numbers in the water samples by the isotachophoresis method were 3.70 × 10(5) cell/mL and 2.62 × 10(4) cell/mL, which were slightly higher than the 9.50 × 10(4) cell/mL and 1.96 × 10(4) cell/mL obtained by conventional microbiological plate counting. PMID:23208770

Phung, Sui Ching; Nai, Yi Heng; Powell, Shane M; Macka, Mirek; Breadmore, Michael C

2013-02-18

43

LOGARITHMIC AMPLIFIER  

DOEpatents

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

De Shong, J.A. Jr.

1957-12-31

44

Design of a radiation-hardened, low-noise, high-speed charge pre-amplifier for the Superconducting Super Collider  

Microsoft Academic Search

A charge preamplifier which has been developed for the warm-liquid calorimeter experiments in the Superconducting Super Collider (SSC) is presented. The amplifier has been designed for implementation in a Harris dielectrically isolated, radiation-hardened, very-high-frequency BiFET IC technology. SPICE simulations after 3 Mrd of gamma ray and 3×1014\\/cm2 of neutron exposure show that the amplifier has high gain (0.5 V\\/1 pC),

L. Wurtz; D. DiBitonto

1990-01-01

45

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

PubMed

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

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

2010-04-01

46

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

NASA Astrophysics Data System (ADS)

Thiophene/phenylene co-oligomers have substantial promise for the use of not only organic electronics but also organic optical devices. However, considerably less is known about the correlation between their optical and optoelectronic properties. We have investigated the charge carrier generation in 1,4-bis(5-phenylthiophen-2-yl)benzene (AC5) single crystals by flash-photolysis time-resolved microwave conductivity (TRMC) and transient absorption spectroscopy (TAS). It was found that the dependence of photocarrier generation efficiency on excitation photon density differed from that of emission efficiency once amplified spontaneous emission (ASE) and resultant spectrally narrowed emission occur upon exposure to 355 nm. In contrast, the dependences of emission and photocarrier generation efficiencies were identical when ASE was not involved at a different excitation wavelength (193 nm). An approximated analytical solution of rate equation considering ASE or singlet-singlet annihilation was applied to the experiments, exhibiting good agreement. On the basis of TRMC, TAS, and extinction coefficient of radical cation assessed by pulse radiolysis, the minimum charge carrier mobility was estimated, without electrodes, to be 0.12 cm2 V-1 s-1. The dynamics of charge carrier and triplet excited state is discussed, accompanying with examination by time-dependent density functional theory. The present work would open the way to a deeper understanding of the fate of excited state in optically robust organic semiconducting crystals.

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

2010-04-01

47

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

SciTech Connect

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.

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

1999-06-01

48

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

SciTech Connect

We describe the design and optimization of low-noise, single-stage output amplifiers for p-channel charge-coupled devices (CCDs) used for scientific applications in astronomy and other fields. The CCDs are fabricated on high-resistivity, 4000–5000 -cm, n-type silicon substrates. Single-stage amplifiers with different output structure designs and technologies have been characterized. The standard output amplifier is designed with an n{sup +} polysilicon gate that has a metal connection to the sense node. In an effort to lower the output amplifier readout noise by minimizing the capacitance seen at the sense node, buried-contact technology has been investigated. In this case, the output transistor has a p{sup +} polysilicon gate that connects directly to the p{sup +} sense node. Output structures with buried-contact areas as small as 2 ?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{sup ?} rms at 70 kpixels/sec.

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

2011-12-22

49

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

50

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

National Technical Information Service (NTIS)

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 pul...

N. Hopps

1998-01-01

51

Conjugated self-doped polyaniline-DNA hybrid as trigger for highly sensitive reagentless and electrochemical self-signal amplifying DNA hybridization sensing.  

PubMed

In very recent years, polyaniline or its derivatives have been adopted to efficiently immobilize probe DNA via ?-? interaction between conjugated interface and DNA bases. In this work, self-doped polyaniline (SPAN)-DNA hybrid was adopted as the platform to construct a DNA biosensor with label-free, reagentless and electrochemical self-signal amplifying features. This was achieved by the ?-? interaction between conjugated SPAN and DNA bases, also the intrinsic differences between single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). The tightly cross-linked hybrid was tethered to Au electrode, which had been anchored by p-aminothiophenol (PATP) self-assembled monolayer (SAM) previously, based on the phosphoramidate bond between PATP and ssDNA. SPAN in the recognition surface exhibited well-defined redox signals under neutral conditions. Due to the intrinsic property differences between ssDNA and dsDNA, such as rigidity, ?-stacked bases, charge distribution and long-range electron transfer, SPAN-DNA underwent a major conformational change after hybridization. The redox behaviors of SPAN were modulated by DNA, which served as signals to monitor hybridization. As an example, the gene fragment related to one of the screening genes for the genetically modified plants, cauliflower mosaic virus 35S gene was satisfactorily detected with this strategy. Under optimal conditions, the dynamic range for the DNA assay was from 1.0 × 10(-14) mol L(-1) to 1.0 × 10(-8) mol L(-1) with the detection limit of 2.3 × 10(-15) mol L(-1). This work presents the construction of a recognition surface for the highly-sensitive electrochemical DNA hybridization detection via the self-signal amplifying procedure of conjugated SPAN-DNA hybrid. Unlike most signal amplifying processes using outer indicators, complex labels or other reagents, this procedure possesses simplicity and convenience. PMID:23304697

Hu, Yuwei; Yang, Tao; Li, Qianhe; Guan, Qian; Jiao, Kui

2013-02-21

52

Linear circuit applications of operational amplifiers  

Microsoft Academic Search

Some of the most frequently encountered linear circuit applications of operational amplifiers are discussed in this article. Included are details of differential dc amplifiers, bridge amplifiers, analog integrators, differentiators, line-driving amplifiers, ac coupled feedback amplifiers, current-to-voltage converters, reference-voltage sources, voltage regulators, current amplifiers, and charge amplifiers.

Larry L. Schick

1971-01-01

53

Capillary electrophoresis with field-amplified sample stacking for rapid and sensitive determination of sulfadiazine and sulfamethoxazole.  

PubMed

A new capillary electrophoresis method with field-amplified sample stacking (FASS) was developed for the analysis of sulfadiazine and sulfamethoxazole. After optimization of the separation and concentration conditions, the two compounds can be separated within 7 min and quantified with high sensitivity, with detection limits of 0.48 ng/mL for sulfadiazine and 0.76 ng/mL for sulfamethoxazole. This resulted in a 300-1500-fold improvement in concentration sensitivity relative to conventional capillary electrophoresis methods. The method was useful for qualitative and quantitative analysis of sulfadiazine and sulfamethoxazole in their preparations with recovery of 99.0%-102% for sulfadiazine and 99.5% - 99.7% for sulfamethoxazole. PMID:23016449

Li, Yuqin; Cui, Yingjie; Jia, Baoxiu; Wang, Hao; Liu, Caihong; Qi, Yongxiu

2012-09-01

54

Bipolar pulsed reset for AC coupled charge-sensitive preamplifiers  

SciTech Connect

A new type of charge restoration is described for use particularly in germanium gamma-ray spectrometers for accelerator and space physics applications. A bipolar pulsed reset technique is applied to these applications for the first time. This technique overcomes the problems introduced by the need to AC couple detectors and the fact that very large energy depositions occur due to charged particles present in substantial fluxes, particularly in space. The circuit is described and experimental results are presented and discussed.

Landis, D.A.; Madden, N.M.; Goulding, F.S.

1997-07-01

55

Sensitivity of Carbon Nanotube Transistors to a Charged Dielectric Coating  

Microsoft Academic Search

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

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

2008-01-01

56

Conformational control of benzophenone-sensitized charge transfer in dinucleotides.  

PubMed

Charge transfer in DNA cannot be understood without addressing the complex conformational flexibility, which occurs on a wide range of timescales. In order to reduce this complexity four dinucleotide models consisting of benzophenone linked by a phosphodiester to one of the natural nucleosides = , , , were studied in water and methanol. The theoretical work focuses on the dynamics and electronic structure of . Predominant conformations in the two solvents were obtained by molecular dynamics simulations. in MeOH adopts mainly an open geometry with a distance of 12-16 Å between the two aromatic parts. In H2O the two parts of form primarily a stacked conformation yielding a distance of 5-6 Å. The low-lying excited states were investigated by electronic structure theory in a QM/MM environment for representative snapshots of the trajectories. Photo-induced intramolecular charge transfer in the S1 state occurs exclusively in the stacked conformation. Ultrafast transient absorption spectroscopy with reveals fast charge transfer from S1 in both solvents with varying yields. Significant charge transfer from the T1 state is only found for the nucleobases with the lowest oxidation potential: in H2O, charge transfer occurs with 3.2 × 10(9) s(-1) for and 6.0 × 10(9) s(-1) for . The reorganization energy remains nearly unchanged going from MeOH to the more polar H2O. The electronic coupling is rather low even for the stacked conformation with HAB = 3 meV and explains the moderate charge transfer rates. The solvent controls the conformational distribution and therefore gates the charge transfer due to differences in distance and stacking. PMID:24084688

Merz, Thomas; Wenninger, Matthias; Weinberger, Michael; Riedle, Eberhard; Wagenknecht, Hans-Achim; Schütz, Martin

2013-10-01

57

Surface charge and properties of cardiac ATP-sensitive K+ channels  

Microsoft Academic Search

ATP-sensitive K + (KATP) channels are present in a wide variety of tissues. The sensitivity of these channels to closure by cytosolic ATP (ATPi) varies significantly among different tissues and even within the same tissue. The purpose of this study was to test the hypothesis that negative surface charges modulate the sensitivity of the KATe channels to ATPi by influencing

NICHOLAS DEUTSCH; JAMES N. WEISS

1994-01-01

58

Charge collection and SEU sensitivity for Ga/As bipolar devices  

SciTech Connect

This paper reports charge collection measured across the base-emitter heterojunction to test certain assumptions of the standard sensitive volume models for calculating SEU rates. The observed dependence of charge collection on the LET (linear energy transfer) and the angle of incidence of alphas and 20 MeV Oxygen ions is consistent with the hypothesis that the charge collected equals the product of LET and pathlength through a sensitive volume of fixed dimensions. The data suggest that the switch from MBE to MOCVD processing resulted in an increase in the thickness of the sensitive volume from 0.11 to 0.25 microns.

Yaktieen, M.H.; McNulty, P.J.; Lynch, J.E.; Roth, D.R. (Dept. of Physics and Astronomy, Clemson Univ., Clemson, SC (US)); Salzman, J.F.; Yuan, J.H. (Texas Instruments, Dallas, TX (US))

1989-12-01

59

A wireless and sensitive detection of octachlorostyrene using modified AuNPs as signal-amplifying tags.  

PubMed

A wireless, remote query octachlorostyrene (OCS) biosensor was fabricated by coating a mass-sensitive magnetoelastic ribbon with anti-OCS antibody. In response to a time-varying magnetic field, the magnetoelastic sensor mechanically vibrates at a characteristic resonance frequency which inversely depends on the sensor mass loading. As the magnetoelastic film is magnetostrictive itself, the vibrations launch magnetic flux that can be remotely detected using a pickup coil. Au nanoparticles (NPs) were used to amplify the mass loading. In a sample solution containing OCS target and OCS-modified AuNPs (OCS-AuNPs), both OCS and OCS-AuNPs react with the anti-OCS antibody immobilized on the sensor surface in a competition mode. The bound OCS-AuNPs amount is inversely proportional to the OCS target concentration. The reduction of bound OCS-AuNPs induced by free OCS results in significant change in mass loading, which amplifies the responses. The biosensor demonstrates a linear shift in resonance frequency with OCS concentration between 7.4?M and 9nM, with a detection limit of 2.8nM. PMID:24135481

Chen, Lan; Li, Jiezhen; Thanhthuy, T Tran; Zhou, Liping; Huang, Chen'an; Yuan, Lijuan; Cai, Qingyun

2013-09-11

60

A Highly Sensitive Enzyme-Amplified Immunosensor Based on a Nanoporous Niobium Oxide (Nb2O5) Electrode  

PubMed Central

We report on the development of an enzyme-amplified sandwich-type immunosensor based on a thin gold film sputtered on an anodic nanoporous niobium oxide (Au@Nb2O5) electrode. The electrocatalytic activity of enzymatically amplified electroactive species and a stable electrode consisting of Au@Nb2O5 were used to obtain a powerful signal amplification of the electrochemical immunobiosensor. The method using this electrochemical biosensor based on an Au@Nb2O5 electrode provides a much better performance than those based on conventional bulk gold or niobium oxide electrodes. Our novel approach does not require any time-consuming cleaning steps to yield reproducible electrochemical signals. In addition, the strong adhesion of gold films on the niobium oxide electrodes offers a very stable substrate during electrochemical biosensing. Cyclic voltammetry measurements indicate that non-specific binding of proteins to the modified Au@Nb2O5 surface is sufficiently low to be ignored in the case of our novel system. Finally, we demonstrated the ability of the biosensor based on an Au@Nb2O5 offering the enhanced performance with a high resolution and sensitivity. Therefore, it is expected that the biosensor based on an Au@Nb2O5 has great potential for highly efficient biological devices.

Lee, Chang-Soo; Kwon, Dohyoung; Yoo, Jeng Eun; Lee, Byung Gun; Choi, Jinsub; Chung, Bong Hyun

2010-01-01

61

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

SciTech Connect

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

Li, H.

1993-01-01

62

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

Microsoft Academic Search

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

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

2010-01-01

63

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

Microsoft Academic Search

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

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

2010-01-01

64

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

PubMed Central

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, ?13 elementary charges. A Shaker subunit's primary voltage-sensing (S4) region has seven positively charged residues. The Shab channel and its homologue Kv2.1 both carry a delayed-rectifier current, and their subunits have only five positively charged residues in S4; they would be expected to have smaller gating-charge movements and voltage sensitivities. We have characterized the gating currents and single-channel behavior of Shab channels and have estimated the charge movement in Shaker, Shab, and their rat homologues Kv1.1 and Kv2.1 by measuring the voltage dependence of open probability at very negative voltages and comparing this with the charge–voltage relationships. We find that Shab has a relatively small gating charge, ?7.5 eo. Surprisingly, the corresponding mammalian delayed rectifier Kv2.1, which has the same complement of charged residues in the S2, S3, and S4 segments, has a gating charge of 12.5 eo, essentially equal to that of Shaker and Kv1.1. Evidence for very strong coupling between charge movement and channel opening is seen in two channel types, with the probability of voltage-independent channel openings measured to be below 10?9 in Shaker and below 4 × 10?8 in Kv2.1.

Islas, Leon D.; Sigworth, Fred J.

1999-01-01

65

Sensitive and Specific KRAS Somatic Mutation Analysis on Whole-Genome Amplified DNA from Archival Tissues  

PubMed Central

Kirsten RAS (KRAS) is a small GTPase that plays a key role in Ras/mitogen-activated protein kinase signaling; somatic mutations in KRAS are frequently found in many cancers. The most common KRAS mutations result in a constitutively active protein. Accurate detection of KRAS mutations is pivotal to the molecular diagnosis of cancer and may guide proper treatment selection. Here, we describe a two-step KRAS mutation screening protocol that combines whole-genome amplification (WGA), high-resolution melting analysis (HRM) as a prescreen method for mutation carrying samples, and direct Sanger sequencing of DNA from formalin-fixed, paraffin-embedded (FFPE) tissue, from which limited amounts of DNA are available. We developed target-specific primers, thereby avoiding amplification of homologous KRAS sequences. The addition of herring sperm DNA facilitated WGA in DNA samples isolated from as few as 100 cells. KRAS mutation screening using high-resolution melting analysis on wgaDNA from formalin-fixed, paraffin-embedded tissue is highly sensitive and specific; additionally, this method is feasible for screening of clinical specimens, as illustrated by our analysis of pancreatic cancers. Furthermore, PCR on wgaDNA does not introduce genotypic changes, as opposed to unamplified genomic DNA. This method can, after validation, be applied to virtually any potentially mutated region in the genome.

van Eijk, Ronald; van Puijenbroek, Marjo; Chhatta, Amiet R.; Gupta, Nisha; Vossen, Rolf H.A.M.; Lips, Esther H.; Cleton-Jansen, Anne-Marie; Morreau, Hans; van Wezel, Tom

2010-01-01

66

High power rf amplifiers for accelerator applications: The large orbit gyrotron and the high current, space charge enhanced relativistic klystron  

SciTech Connect

Los Alamos is investigating a number of high power microwave sources for their potential to power advanced accelerators. Included in this investigation are the large orbit gyrotron amplifier and oscillator (LOG) and the relativistic klystron amplifier (RKA). LOG amplifier development is newly underway. Electron beam power levels of 3 GW, 70 ns duration, are planned, with anticipated conversion efficiencies into RF on the order of 20 percent. Ongoing investigations on this device include experimental improvement of the electron beam optics, and computational studies of resonator design and RF extraction. Recent RKA studies have operated at electron beam powers into the device of 1.35 GW in microsecond duration pulses. The device has yielded modulated electron beam power approaching 300 MW using 3--5 kW of RF input drive. RF powers extracted into waveguide have been up to 70 MW, suggesting that more power is available from the device that we have converted to-date in the extractor. We have examined several aspects of operation, including beam bunching phenomena and RF power extraction techniques. In addition, investigations of the amplifier gain as a function of input drive, electron beam parameters and axial magnetic field strength also have been explored. The effect of ions formed during device operation also has been considered.

Stringfield, R.M.; Fazio, M.V.; Rickel, D.G.; Kwan, T.J.T.; Peratt, A.L.; Kinross-Wright, J.; Van Haaften, F.W.; Hoeberling, R.F.; Faehl, R.; Carlsten, B.; Destler, W.W.; Warner, L.B.

1990-01-01

67

Method and apparatus for detection of charge on ions and particles  

DOEpatents

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.

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

2002-01-01

68

Novel phage amplified multichannel series piezoelectric quartz crystal sensor for rapid and sensitive detection of Mycobacterium tuberculosis.  

PubMed

The key factors that control the spread and mortality rate of tuberculosis (TB) are rapid detection and diagnosis. However, the current detection of Mycobacterium tuberculosis (M. tuberculosis) cannot meet the recommended requirements for clinical diagnosis in turnaround time. In this paper, the feature of phage D29 that infects M. tuberculosis and Mycobacterium smegmatis (M. smegmatis) was combined with the sensitivity of multichannel series piezoelectric quartz crystal sensor (MSPQC) to detect M. tuberculosis. The phage D29 played a role of inhibiting the growth of M. tuberculosis and M. smegmatis. M. tuberculosis is used to protect phage D29 from being killed by ferrous ammonium sulfate (FAS) and carries phage D29 into the detection medium containing M. smegmatis. The action of M. smegmatis indicated the existence state of phage D29 in the detection medium. The growth curve of M. smegmatis obtained by MSPQC indicated the state of the growth of M. tuberculosis. Therefore, M. tuberculosis in the sample could be rapidly detected by evaluating the extent of inhibiting the growth of M. smegmatis compared with the normal growth of M. smegmatis. The detection of M. tuberculosis was transformed into the detection of M. smegmatis, which is more rapid and sensitive than that of M. tuberculosis. For 10(2) cfu/mL of M. tuberculosis in clinical sample, the turnaround time was less than 30 h. Although statistical analysis showed that no significant difference existed between the results of the proposed method here and the BACTEC960 MGIT method in clinical M. tuberculosis detection, the phage amplified MSPQC (PA MSPQC) method presented here was faster and more economical. PMID:22142398

Mi, Xianwen; He, Fengjiao; Xiang, Meiyu; Lian, Yan; Yi, Songlin

2011-12-22

69

Charge collection and SEU sensitivity for Ga/As bipolar devices  

NASA Astrophysics Data System (ADS)

Charge collection was measured across the base-emitter heterojunction to test certain assumptions of the standard sensitive-volume models for calculating SEU (single-event-upset) rates. The observed dependence of charge collection on the LET (linear energy transfer) and the angle of incidence of 4.4-MeV alphas and 20-MeV oxygen ions is consistent with the hypothesis that the charge collected equals the product of LET and path length through a sensitive volume of fixed dimensions. The data suggest that the switch from MBE (molecular beam epitaxy) to MOCVD (metal-organic chemical vapor deposition) processing resulted in an increase in the thickness of the sensitive volume from 0.11 to 0.25 micron.

Yaktieen, M. H.; McNulty, P. J.; Lynch, J. E.; Roth, D. R.; Salzman, J. F.

1989-12-01

70

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

PubMed Central

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.

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

2012-01-01

71

Charge collection and absorption-limited x-ray sensitivity of pixellated x-ray detectors  

NASA Astrophysics Data System (ADS)

The charge collection and absorption-limited x-ray sensitivity of a direct conversion pixellated x-ray detector operating in the presence of deep trapping of charge carriers is calculated using the Shockley-Ramo theorem and the weighting potential of the individual pixel. The sensitivity of a pixellated x-ray detector is analyzed in terms of normalized parameters; (a) the normalized x-ray absorption depth (absorption depth/photoconductor thickness), (b) normalized pixel width (pixel size/thickness), and (c) normalized carrier schubwegs (schubweg/thickness). The charge collection and absorption-limited sensitivity of pixellated x-ray detectors mainly depends on the transport properties (mobility and lifetime) of the charges that move towards the pixel electrodes and the extent of dependence increases with decreasing normalized pixel width. The x-ray sensitivity of smaller pixels may be higher or lower than that of larger pixels depending on the rate of electron and hole trapping and the bias polarity. The sensitivity of pixellated detectors can be improved by ensuring that the carrier with the higher mobility-lifetime product is drifted towards the pixel electrodes. .

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

2004-05-01

72

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

Microsoft Academic Search

We study atomic systems that are in the frequency range of optical atomic\\u000aclocks and have enhanced sensitivity to potential time-variation of the fine\\u000astructure constant, alpha. The high sensitivity is due to coherent\\u000acontributions from three factors: high nuclear charge Z, high ionization\\u000adegree, and significant differences in the configuration composition of the\\u000astates involved. Configuration crossing keeps the

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

2010-01-01

73

A wide bandwidth, high linearity hybrid charge-sensitive preamplifier for high-capacitance silicon detectors  

Microsoft Academic Search

A new hybrid charge-sensitive preamplifier with a sensitivity of 5 mV\\/MeV has been specifically designed to operate in conjunction with high-capacitance silicon detectors. The shape of the leading edge of its impulse response keeps fast (20 ns) and unchanged over the full output voltage swing (7 V), as is required in nuclear-physics experiments in which Pulse-Shape Analysis is used for

Roberto Bassini; Ciro Boiano; Angelo Pagano; Alberto Pullia

2003-01-01

74

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

PubMed Central

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

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

2011-01-01

75

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

Microsoft Academic Search

Battery electric vehicles (BEVs) offer the potential to reduce both oil imports and greenhouse gas emissions, but high upfront costs discourage many potential purchasers. Making an economic comparison with conventional alternatives is complicated in part by strong sensitivity to drive patterns, vehicle range, and charge strategies that affect vehicle utilization and battery wear. Identifying justifiable battery replacement schedules and sufficiently

J. Neubauer; A. Brooker; E. Wood

2012-01-01

76

Amplifier with time-invariant trapezoidal shaping and shape-sensitive pileup rejector for high-rate spectroscopy  

Microsoft Academic Search

An amplifier with trapezoidal pulse shaping was developed for high-rate high-energy gamma spectroscopy using NaI(T1) scintillation detectors. It employs a double delay-line technique for producing a nearly triangular pulse shape combined with a linear circuit for producing a flattopped pulse. Good energy resolution and short resolving time make this amplifier especially suitable for high count rate gamma ray spectroscopy. To

V. Drndarevic; P. Ryge; T. Gozani

1989-01-01

77

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

NASA Astrophysics Data System (ADS)

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.

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

2010-09-01

78

Analysis of urinary neurotransmitters by capillary electrophoresis: Sensitivity enhancement using field-amplified sample injection and molecular imprinted polymer solid phase extraction  

Microsoft Academic Search

Capillary electrophoresis (CE) has been investigated for the analysis of some neurotransmitters, dopamine (DA), 3-methoxytyramine (3-MT) and serotonin (5-hydroxytryptamine, 5-HT) at nanomolar concentrations in urine. Field-amplified sample injection (FASI) has been used to improve the sensitivity through the online pre-concentration samples. The cationic analytes were stacked at the capillary inlet between a zone of low conductivity - sample and pre-injection

Bérengère Claude; Reine Nehmé; Philippe Morin

2011-01-01

79

PULSE AMPLIFIER  

DOEpatents

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

Johnstone, C.W.

1958-06-17

80

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

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

81

Modeling of trap assisted interfacial charge transfer in dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

This paper presents a model for charge transport in dye sensitized solar cells based on the physics of electron capture, electron emission, oxidation, and reduction processes mediated by deep interfacial trap states at TiO2/dye/electrolyte interfaces. This model suggests that electron back injection from the conduction band of TiO2 to electrolyte is due to trapping of conduction band electrons by deep states followed by reduction processes at the interface. The simulated dark IV, illuminated IV, and quantum efficiency characteristics of dye sensitized solar cells based on this model are consistent with experimental results.

Nepal, Jeevan; Sadegh Mottaghian, Seyyed; Biesecker, Matt; Farrokh Baroughi, Mahdi

2013-05-01

82

Charge sensitivity approach to mutual polarization of reactants: molecular mechanics perspective.  

PubMed

Charge sensitivity analysis (CSA) in force-field atoms resolution was applied to describe the mutual polarization of reactants as well as charge-transfer (CT) effects. An inclusion complex of ?-cyclodextrin with salicylic acid was used as a model system. Three CSA models were taken into account and verified on a Born-Oppenheimer molecular dynamics (BOMD) trajectory. The models differed in terms of the equilibrium conditions imposed on the system. It was demonstrated that mutual polarization is an important source of stabilization, in contrast to the results obtained from static charge calculations. The energy lowering induced by CT was small and comparable to the CT stabilization that occurs in hydrogen-bonded systems. All models correctly described the main topological features of the BOMD energy surface. CSA in force-field atoms resolution qualitatively reproduced the charge reorganization accompanying hydrogen-bond formation. It was shown that CSA parameters are very sensitive to the bond formation process, which suggests that they could be applied in reactive force fields as detectors of newly formed chemical bonds. PMID:23392762

Stachowicz, Anna; Rogalski, Marek; Korchowiec, Jacek

2013-02-08

83

On the methods of calculation of the charge collection efficiency of dye sensitized solar cells.  

PubMed

The charge collection efficiency is one of the most critical parameters of photovoltaic devices. In this paper we provide the analysis and comparison between several approaches for the calculation of the collection efficiency of dye-sensitized solar cells. In addition, we point out that although it is reasonable to correlate transit time and recombination lifetime with respect to diffusion length, it is less physical to directly calculate collection efficiency only based on characteristic time constants. PMID:23416949

Bertoluzzi, Luca; Ma, Shuai

2013-03-28

84

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

SciTech Connect

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

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

2012-07-01

85

A quasi-quantum well sensitized solar cell with accelerated charge separation and collection.  

PubMed

Semiconductor-sensitized solar cell (SSSC) represents a new generation of device aiming to achieve easy fabrication and cost-effective performance. However, the power of the semiconductor sensitizers has not been fully demonstrated in SSSC, making it actually overshadowed by dye-sensitized solar cell (DSSC). At least part of the problem is related to the inefficient charge separation and severe recombination with the current technologies, which calls on rethinking about how to better engineer the semiconductor sensitizer structure in order to enhance the power conversion efficiency (PCE). Herein we report on using for the first time a quasi-quantum well (QW) structure (ZnSe/CdSe/ZnSe) as the sensitizer, which is quasi-epitaxially deposited on ZnO tetrapods. Such a novel photoanode architecture has attained 6.20% PCE, among the highest reported to date for this type of SSSCs. Impedance spectra have revealed that the ZnSe/CdSe/ZnSe QW structure has a transport resistance only a quarter that of, but a recombination resistance twice that of the ZnSe/CdSe heterojunction (HJ) structure, yielding much longer electron diffusion length, consistent with the resulting higher photovoltage, photocurrent, and fill factor. Time-resolved photoluminescence spectroscopy indicates dramatically reduced electron transfer from ZnO to the QW sensitizer, a feature which is conducive to charge separation and collection. This study together with the impedance spectra and intensity modulated photocurrent spectroscopies supports a core/shell two-channel transport mechanism in this type of solar cells and further suggests that the electron transport along sensitizer can be considerably accelerated by the QW structure employed. PMID:23731331

Yan, Keyou; Zhang, Lixia; Qiu, Jianhang; Qiu, Yongcai; Zhu, Zonglong; Wang, Jiannong; Yang, Shihe

2013-06-13

86

Laser Amplifier.  

National Technical Information Service (NTIS)

An invention is presented relating to a laser amplifier and, more particularly, to chambers for the containment and energization of an amplifying medium. In a preferred embodiment of the invention, an apparatus is provided for laser amplification with hig...

1978-01-01

87

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

PubMed Central

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

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

2010-01-01

88

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

USGS Publications Warehouse

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

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

1977-01-01

89

A new mussel-inspired polydopamine sensitizer for dye-sensitized solar cells: controlled synthesis and charge transfer.  

PubMed

The efficient electron injection by direct dye-to-TiO(2) charge transfer and strong adhesion of mussel-inspired synthetic polydopamine (PDA) dyes with TiO(2) electrode is demonstrated. Spontaneous self-polymerization of dopamine using dip-coating (DC) and cyclic voltammetry (CV) in basic buffer solution were applied to TiO(2) layers under a nitrogen atmosphere, which offers a facile and reliable synthetic pathway to make the PDA dyes, PDA-DC and PDA-CV, with conformal surface and perform an efficient dye-to-TiO(2) charge transfer. Both synthetic methods led to excellent photovoltaic results and the PDA-DC dye exhibited larger current density and efficiency values than those in the PDA-CV dye. Under simulated AM 1.5?G solar light (100 mW cm(-2)), a PDA-DC dye exhibited a short circuit current density of 5.50 mW cm(-2), corresponding to an overall power conversion efficiency of 1.2 %, which is almost 10 times that of the dopamine dye-sensitized solar cell. The PDA dyes showed strong adhesion with the nanocrystalline TiO(2) electrodes and the interface engineering of a dye-adsorbed TiO(2) surface through the control of the coating methods, reaction times and solution concentration maximized the overall conversion efficiency, resulting in a remarkably high efficiency. PMID:23001762

Nam, Hye Jin; Kim, Boeun; Ko, Min Jae; Jin, Mingshi; Kim, Ji Man; Jung, Duk-Young

2012-09-23

90

Wide-bandwidth charge sensitivity with a radio-frequency field-effect transistor  

NASA Astrophysics Data System (ADS)

We demonstrate high-speed charge detection at room temperature with single-electron resolution by using a radio-frequency field-effect transistor (RF-FET). The RF-FET combines a nanometer-scale silicon FET with an impedance-matching circuit composed of an inductor and capacitor. Driving the RF-FET with a carrier signal at its resonance frequency, small signals at the transistor's gate modulate the impedance of the resonant circuit, which is monitored at high speed using the reflected signal. The RF-FET driven by high-power carrier signals enables a charge sensitivity of 2 × 10-4 e/Hz0.5 at a readout bandwidth of 20 MHz.

Nishiguchi, Katsuhiko; Yamaguchi, Hiroshi; Fujiwara, Akira; van der Zant, Herre S. J.; Steele, Gary A.

2013-09-01

91

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

NASA Astrophysics Data System (ADS)

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%.

Sivaram, Varun; Kirkpatrick, James; Snaith, Henry

2013-02-01

92

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

SciTech Connect

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.

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

1996-06-01

93

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

SciTech Connect

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

Koga, R.; Crain, W.R.; Hansel, S.J.; Crawford, K.B.; Kirshman, J.F.; Pinkerton, S.D.; Penzin, S.H.; Moss, S.C. [Aerospace Corp., El Segundo, CA (United States); Maher, M. [National Semiconductor, South Portland, ME (United States)

1995-12-01

94

Characterization of a new charge sensitive preamplifier (CSP) for the electromagnetic calorimeters of the ALICE experiment  

NASA Astrophysics Data System (ADS)

The ALICE calorimeters PHOS and EMCal (including its extension DCal) are based on Avalanche Photo-Diode (APD) photosensors with Charge Sensitive Preamplifiers (CSPs) for readout of the scintillating elements. A new CSP has been developed on the basis of the design of the PHOS CSP, but modified to meet the requirements of the EMCal and DCal. Modifications were made specifically for a different APD choice with different characteristics, and also with the goals of less noise, faster rise time, and reduced cost. This paper presents a detailed description of the new CSP features and the test results.

Wang, Yaping; Muller, Hans; Cai, Xu; Zhou, Daicui; Awes, Terry C.; Yin, Zhongbao

2012-09-01

95

Non-Solid Explosives for Shaped Charges. Part II. Target Penetration with Metal Liner Devices Using Sensitized Nitromethane Liquid Explosive  

Microsoft Academic Search

In an attempt to overcome the inconsistencies of plastic explosive–filled shape charges in EOD operations we have explored the use of sensitized gelled nitromethane liquid as a filling for a number of shaped charge devices. The ability to penetrate munition casings and induce deflagration is not only dependent on the velocity of detonation of the mixture, investigated in previous papers,

Michael Cartwright; David Lloyd-Roach; Peter J. Simpson

2009-01-01

96

Mu2e: A High-Sensitivity Charged Lepton Flavor-Violating Search at Fermilab  

NASA Astrophysics Data System (ADS)

The Mu2e Experiment at Fermilab will search for coherent, neutrino-less conversion of a muon into an electron in the field of a nucleus, -circ;+A->A+e^-, with a sensitivity improvement of a factor of 10,000 over existing limits. Such a charged lepton flavor-violating reaction probes new physics complementary to the LHC and can reach a scale unavailable by direct searches at either present or planned high energy colliders. The physics motivation for Mu2e will be presented, as well as the design of the muon beamline and spectrometer. The beamline employs a new design consisting of superconducting solenoids that will produce muons at high efficiency. A scheme by which the experiment can be mounted in the present Fermilab accelerator complex will be described. Prospects for increased sensitivity at future very high intensity sources, such as the Project X linac that is being proposed by Fermilab, will be discussed.

Miller, James

2012-03-01

97

An Amplifier Concept for Spintronics  

SciTech Connect

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.

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

98

Simulation of non-linear recombination of charge carriers in sensitized nanocrystalline solar cells  

NASA Astrophysics Data System (ADS)

Electron transport and recombination in electrolyte-filled sensitized nanocrystalline solar cell was investigated using Monte-Carlo simulation. Multiple-trapping in an exponential tail of trap states was used as an electron transport model. For simulation of the recombination, a new approach based on Marcus theory of charge transfer was developed and utilized to simulate both linear and non-linear (trap-assisted) recombination of electrons with holes in the electrolyte. Monte-Carlo simulation results, based on this approach, reproduced the non-constant diffusion length, recently observed in several experimental works. All simulation results were compared with theoretical predictions of the Marcus theory of charge transfer. Based on this comparison, interestingly it was found that random walk electron lifetime is different from the one which is obtained experimentally by small-perturbation techniques. This result is similar to the well-known Darken equation that describes the difference between jump and chemical diffusion coefficient. An interpretation based on the transport-limited recombination picture was provided to describe this result. These simulations establish a clear picture that describes how the localized trap states contribute to the recombination, leading to the non-linear recombination kinetics in sensitized solar cells.

Ansari-Rad, M.; Abdi, Y.; Arzi, E.

2012-10-01

99

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

SciTech Connect

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.

White, J.R.

1981-09-01

100

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

SciTech Connect

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.

White, J.R.

1985-04-01

101

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

NASA Astrophysics Data System (ADS)

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

Lin, Gong-Ru; Liao, Yu-Sheng

2005-04-01

102

Amplifier Distortion  

NASA Astrophysics Data System (ADS)

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

Keeports, David

2006-12-01

103

Maternal Groucho and bHLH repressors amplify the dose-sensitive X chromosome signal in Drosophila sex determination  

PubMed Central

In Drosophila, XX embryos are fated to develop as females, and XY embryos as males, because the diplo-X dose of four X-linked signal element genes, XSEs, activates the Sex-lethal establishment promoter, SxlPe, whereas the haplo-X XSE dose leaves SxlPe off. The threshold response of SxlPe to XSE concentrations depends in part on the bHLH repressor, Deadpan, present in equal amounts in XX and XY embryos. We identified canonical and non-canonical DNA-binding sites for Dpn at SxlPe and found that cis-acting mutations in the Dpn-binding sites caused stronger and earlier Sxl expression than did deletion of dpn implicating other bHLH repressors in Sxl regulation. Maternal Hey encodes one such bHLH regulator but the E(spl) locus does not. Elimination of the maternal corepressor Groucho also caused strong ectopic Sxl expression in XY, and premature Sxl activation in XX embryos, but Sxl was still expressed differently in the sexes. Our findings suggest that Groucho and associated maternal and zygotic bHLH repressors define the threshold XSE concentrations needed to activate SxlPe and that they participate directly in sex signal amplification. We present a model in which the XSE signal is amplified by a feedback mechanism that interferes with Gro-mediated repression in XX, but not XY embryos.

Lu, Hong; Kozhina, Elena; Mahadevaraju, Sharvani; Yang, Dun; Avila, Frank W.; Erickson, James W.

2008-01-01

104

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

SciTech Connect

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

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

1987-02-01

105

Performance of a new monolithic eight channel charge sensitive preamplifier-shaper  

SciTech Connect

A monolithic eight channel CMOS time-invariant preamplifier/shaper has been designed and built by Chuck Britton of ORNL in collaboration with Ray Yarema and Tom Zimmerman of Fermilab. Each of the eight channels incorporates a charge sensitive preamplifier and two shaping stages. The resultant weighting function is similar to CR-RC{sup 3}. The peaking time is approximately 200 ns, and the charge gain approximately in the range of 50--70 mv/fc. The layout was done on a Tinychip pad frame and the device was fabricated in a 2{mu} P-well process by Orbit. Figure 1 shows the chip layout. The channels are on an 84{mu} pitch to fit on a Tinychip without folding the layout. The design can be easily expanded to a larger number of channels. This paper describes results of tests performed on this device at Fermilab. The tests were done with a bare die which was directly wirebonded to a printed circuit board. This minimizes parasitic effects which can become significant when using large packages. Results may be somewhat different when using the standard 40 pin package. 6 figs.

Zimmerman, T.

1991-08-01

106

Computational analysis of the influence of initial fixed charge density on pH-sensitive hydrogels  

NASA Astrophysics Data System (ADS)

In this paper, we conduct a computational analysis of the effects of initial fixed charge density on the responsive performance of pH-sensitive hydrogels to environmental change in solution pH. The analysis is based on a chemo-electro-mechanical formulation previously termed the multi-effect-coupling pH-stimulus (MECpH) model. In this work, we improve the MECpH model by incorporating the finite deformation formulation into the mechanical equilibrium equation. The present model consisting of coupled nonlinear partial differential equations is solved via a meshless numerical technique called the Hermite-cloud method with the modified Newton iteration methodology. After validation of the MECpH model by comparing the computational results with experimental data available in the literature, several computational case studies are carried out for analysis of the effects of initial fixed charge density on the distributive variations of the diffusive ion concentrations and electric potential and on the deformation of the pH-stimulus-responsive hydrogels, when they are immersed in different buffered solutions.

Li, Hua; Yew, Yong Kin; Ng, Teng Yong

2008-12-01

107

Overexpression of the adiponectin receptor AdipoR1 in rat skeletal muscle amplifies local insulin sensitivity.  

PubMed

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

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; Cleasby, M E

2012-09-18

108

Enhanced performance CCD output amplifier  

DOEpatents

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

Dunham, Mark E. (Los Alamos, NM); Morley, David W. (Santa Fe, NM)

1996-01-01

109

Charge density dependent mobility of organic hole-transporters and mesoporous TiO? determined by transient mobility spectroscopy: implications to dye-sensitized and organic solar cells.  

PubMed

Transient mobility spectroscopy (TMS) is presented as a new tool to probe the charge carrier mobility of commonly employed organic and inorganic semiconductors over the relevant range of charge densities. The charge density dependence of the mobility of semiconductors used in hybrid and organic photovoltaics gives new insights into charge transport phenomena in solid state dye sensitized solar cells. PMID:23637046

Leijtens, Tomas; Lim, Jongchul; Teuscher, Joël; Park, Taiho; Snaith, Henry J

2013-05-02

110

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

111

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

PubMed

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 0.1pgmL(-1) to 100ngmL(-1) with a detection limit of 33fgmL(-1) (S/N=3). Additionally, the designed ECL immunosensor exhibited a promising application for other protein detection. PMID:24054635

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

2013-06-21

112

LOGARITHMIC AMPLIFIER  

DOEpatents

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

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

1959-03-10

113

Probing the charge-collection sensitivity profile using a picosecond pulsed laser at a range of wavelengths  

Microsoft Academic Search

A new empirical methodology is defined and demonstrated in which the charge collection sensitivity profile of single-event effect (SEE)-susceptible nodes in microcircuits is calculated on the basis of laser pulse measurements of the upset threshold at a range of wavelengths.

A. M. Chugg; R. Jones; A. Moutrie; C. S. Dyer; C. Sanderson; A. Wraight

2002-01-01

114

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

Microsoft Academic Search

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

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

2007-01-01

115

Experimental observation of sub-femtosecond charge transfer in a model water splitting dye-sensitized solar cell.  

PubMed

Charge transfer from photoexcited dye molecules to a semiconductor substrate forms the basis of dye sensitized solar cells (DSCs); the overall effectiveness of a DSC device is critically dependent upon the efficiency of this process due to competition with other de-excitation channels. In this paper, we experimentally derive timescales for the charge transfer process in model water splitting DSCs. We studied two organometallic dye complexes adsorbed onto a rutile TiO(2)(110) substrate, the dye molecules were deposited in ultra-high vacuum using electrospray deposition. DFT simulations were used to calculate the spatial distribution of orbitals relevant to the charge transfer process. The core-hole clock implementation of resonant photoemission spectroscopy was used to determine upper limits on charge transfer timescales for previously unoccupied orbitals, which were found to be in the low-femtosecond regime apart from one orbital found to have an upper limit in the sub-femtosecond regime. PMID:23249025

Weston, Matthew; Handrup, Karsten; Reade, Thomas J; Champness, Neil R; O'Shea, James N

2012-12-14

116

CMOS Integrating Amplifier for the PHENIX Ring Imaging Cherenkov detector.  

National Technical Information Service (NTIS)

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 sy...

A. L. Wintenberg J. P. Jones G. R. Young C. G. Moscone

1997-01-01

117

Differential transimpedance amplifier circuit for correlated differential amplification  

DOEpatents

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.

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

2008-07-22

118

Operational Amplifiers  

NSDL National Science Digital Library

All About Circuits is a website that âÂÂprovides a series of online textbooks covering electricity and electronics.â Written by Tony R. Kuphaldt, the textbooks available here are wonderful resources for students, teachers, and anyone who is interested in learning more about electronics. This specific section, Operational Amplifiers, is the eighth chapter in Volume III âÂÂSemiconductors. A few of the topics covered in this chapter include: The "operational" amplifier; Negative feedback; Voltage-to-current signal conversion; and Differentiator and integrator circuits. Diagrams and detailed descriptions of concepts are included throughout the chapter to provide users with a comprehensive lesson. Visitors to the site are also encouraged to discuss concepts and topics using the All About Circuits discussion forums (registration with the site is required to post materials).

Kuphaldt, Tony R.

2008-07-14

119

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.

120

[4-channel electroencephalographic amplifier with integrated microcircuits].  

PubMed

To conduct electroencephalographic investigations of stationary and moving objects a small-sized 4-channel amplifier built with integrated microcircuits has been developed. Each channel includes a pre-amplifier, main amplifier, calibrator, high and low frequency filters and a power pack. The adoption of integrated microcircuits enables it to locate the pre-amplifiers directly on the object of investigations. The device is highly sensitive and secures a greater degree of noise-protection. PMID:642753

Zhuravlev, B V; Ozhogin, M A; Simakov, A B; Stepanenko, I P; Sudakov, K V

121

Cryomicroscopy of radiation sensitive specimens on unmodified graphene sheets: Reduction of electron-optical effects of charging?  

PubMed Central

Images of radiation-sensitive specimens obtained by electron microscopy suffer a reduction in quality beyond that expected from radiation damage alone due to electron beam-induced charging or movement of the specimen. For biological specimens, charging and movement are most severe when they are suspended in an insulating layer of vitreous ice, which is otherwise optimal for preserving hydrated specimens in a near native state. We image biological specimens, including a single particle protein complex and a lipid-enveloped virus in thin, vitreous ice films over suspended sheets of unmodified graphene. We show that in such preparations, the charging of ice, as assessed by electron-optical perturbation of the imaging beam, is eliminated. We also use the same specimen supports to record high resolution images at liquid nitrogen temperature of monolayer paraffin crystals grown over graphene.

Sader, Kasim; Stopps, Martyn; Calder, Lesley J.; Rosenthal, Peter B.

2013-01-01

122

Systematic Prediction of Dyes for Dye Sensitized Solar Cells: Data-mining via Molecular Charge-Transfer Algorithms  

Microsoft Academic Search

Graph theoretical algorithms and classification tests are combined with data-mining tools to present successful predictions of high-performance dyes for dye-sensitized solar cells (DSCs). The construction of molecular charge-transfer algorithms is described, featuring recursive depth-first, back-tracking, graph traversal algorithms with classification test formalisms. These algorithms are employed to search through a representative set of organic chemical space (120,000 chemical molecules) to

Jacqueline M. Cole

2011-01-01

123

A varied shaping time noise analysis of Al0.8Ga0.2As and GaAs soft X-ray photodiodes coupled to a low-noise charge sensitive preamplifier  

NASA Astrophysics Data System (ADS)

The noise sources affecting Al0.8Ga0.2As and GaAs spectroscopic X-ray photon counting p+-i-n+ photodiodes connected to a custom low-noise charge sensitive preamplifier are quantified by analysing the system's response to pulses from a signal generator and varying the system's shaping amplifier's shaping time (from 0.5 ?s to 10 ?s). The system is investigated at three temperatures (-10 °C, +20 °C and +50 °C) in order to characterise the variation of the component noise sources and optimum shaping time with temperature for Al0.8Ga0.2As and GaAs diodes. The analysis shows that the system is primarily limited by dielectric noise, hypothesised to be mainly from the packaging surrounding the detector, for both types of diode and at each temperature.

Barnett, A. M.; Lees, J. E.; Bassford, D. J.; Ng, J. S.

2012-05-01

124

High dynamic range charge measurements  

SciTech Connect

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

De Geronimo, Gianluigi

2012-09-04

125

Phase-measurement sensitivity beyond the standard quantum limit in an interferometer consisting of a parametric amplifier and a beam splitter  

NASA Astrophysics Data System (ADS)

We analyze a nonconventional interferometer that is formed with a parametric amplifier and a beam splitter for beam splitting and recombination. Because the outputs from a parametric amplifier are entangled and their quantum noise is correlated, the employment of the beam splitter will superimpose the two quantum fields and the destructive interference will lead to the subtraction of the quantum noise and to noise reduction in the output of the interferometer and hence an improvement of the signal-to-noise ratio (SNR) beyond the standard quantum limit or the shot noise limit. Furthermore, the injection of a squeezed state into the idler port of the parametric amplifier will lead to further improvement of the SNR. We will discuss the possibility of reaching the Heisenberg limit in such an interferometer. We find that the injection of a coherent state will degrade the performance in reaching the Heisenberg limit, whereas a squeezed state injection can improve it by a factor of 2 at best.

Kong, Jia; Ou, Z. Y.; Zhang, Weiping

2013-02-01

126

Sensitivity analysis of combustion timing and duration of homogeneous charge compression ignition (HCCI) engines  

Microsoft Academic Search

The goal of this paper is to investigate which factors have a more dominant effect and should be included in a control oriented model that predicts the start of combustion and combustion duration of a homogeneous charge compression ignition (HCCI) engine. Qualitative and quantitative information on the individual effects of fuel and exhaust gas recirculation (EGR) on the HCCI combustion

C. J. Chiang; A. G. Stefanopoulou

2006-01-01

127

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

PubMed Central

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.

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.; Schadler, L.; Schmitt, B.; Shi, X.; Sobott, B.

2012-01-01

128

Direct Method of Determining the Sensitivity of Microcrystals to Charge Particles.  

National Technical Information Service (NTIS)

As we know from literature which is devoted to founding and developing semiconductor radiation detectors, a charged particle, braked in a solid, expends on the formation of an unbalanced pair of carriers the same amount of energy, regardless of its mass, ...

A. P. Zhdanov I. M. Kuks

1968-01-01

129

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

SciTech Connect

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.

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

1980-06-12

130

From flat to nanostructured photovoltaics: balance between thickness of the absorber and charge screening in sensitized solar cells.  

PubMed

Nanoporous metal oxide electrodes provide a high internal area for dye anchoring in dye-sensitized solar cells, but the thickness required to extinguish the solar photons also enhances recombination at the TiO(2)/electrolyte interface. The high extinction coefficient of inorganic semiconductor absorber should allow the reduction of the film thickness, improving the photovoltage. Here we study all-solid semiconductor sensitized solar cells, in the promising TiO(2)/Sb(2)S(3)/P3HT configuration. Flat and nanostructured cells have been prepared and analyzed, developing a cell performance model, based on impedance spectroscopy results, that allows us to determine the impact of the reduction of metal oxide film thickness on the operation of the solar cell. Decreasing the effective surface area toward the limit of flat samples produces a reduction in the recombination rate, increasing the open circuit potential, V(oc), while providing a significant photocurrent. However, charge compensation problems as a consequence of inefficient charge screening in flat cells increase the hole transport resistance, lowering severely the cell fill factor. The use of novel structures balancing recombination and hole transport will enhance solid sensitized cell performance. PMID:22175224

Boix, Pablo P; Lee, Yong Hui; Fabregat-Santiago, Francisco; Im, Sang Hyuk; Mora-Sero, Ivan; Bisquert, Juan; Seok, Sang Il

2011-12-23

131

High Receiver Sensitivity at 2.5 Gb/s Obtained with a Highly Efficient Low Noise Diode Pumped Erbium Doped Fiber Amplifier.  

National Technical Information Service (NTIS)

Laser diode pumped Erbium doped fiber amplifiers (EDFA) with low noise figures and high saturation powers are attractive because the ratio between the saturation power and the noise figure can be considered as a figure of merit for several applications. T...

B. Mikkelsen C. G. Joergensen J. A. Van Den Berk C. F. Pedersen C. C. Larsen

1992-01-01

132

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

SciTech Connect

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.

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

133

The use of pH-sensitive positively charged polymeric micelles for protein delivery.  

PubMed

In this investigation, a nano-sized protein-encapsulated polymeric micelle was prepared by self-assembling human serum albumin (HSA) as a model protein and degradable block copolymer methoxy poly(ethylene glycol)-poly(?-amino ester) (PEG-PAE) with piperidine and imidazole rings. From the zeta potential measurement, the protein-encapsulated polymeric micelle showed a pH-tuning charge conversion from neutral to positive when pH decreases from 7.8 to 6.2. It was envisioned that the pH-tunable positively charged polymeric micelle could enhance the protein delivery efficiency and, simultaneously, target to the pH-stimuli tissue, such as cancerous tissue or ischemia. The pH-dependent particle size and scattering intensity were also measured and showed 50-70 nm particle size. Consequently, the circular dichroism (CD) spectroscopy confirmed that the secondary structure of albumin was unaffected during the pH changing process. The in vitro cytotoxicity for the polymeric micelle was evaluated on MDA-MB-435 cell lines and no obvious toxicity could be observed when the polymer concentration was below 200 ?g/mL. To assess the ability of this pH-tunable positively charged polymeric micelle as a vehicle for protein delivery to in vivo acidic tissues, we utilized a disease rat model of cerebral ischemia that produced an acidic tissue due to its pathologic condition. The rat was intravenously injected with the Cy5.5-labled albumin-encapsulated polymeric micelle. We found a gradual increase in fluorescence signals of the brain ischemic area, indicating that the pH-tuning positively charged protein-encapsulated polymeric micelle could be effective for targeting the acidic environment and diagnostic imaging. PMID:23000386

Gao, Guang Hui; Park, Min Jung; Li, Yi; Im, Geun Ho; Kim, Jae-Hoon; Kim, Hun Nyun; Lee, Jae Won; Jeon, Pyoung; Bang, Oh Young; Lee, Jung Hee; Lee, Doo Sung

2012-09-20

134

Monolithic pixel detectors in a 0.13 ? m CMOS technology with sensor level continuous time charge amplification and shaping  

Microsoft Academic Search

This work studies the feasibility of a new implementation of CMOS monolithic active pixel sensors (MAPS) for applications to charged particle tracking. As compared to standard three MOSFET MAPS, where the charge signal is readout by a source follower, the proposed front-end scheme relies upon a charge sensitive amplifier (CSA), embedded in the elementary pixel cell, to perform charge-to-voltage conversion.

L. Ratti; M. Manghisoni; V. Re; V. Speziali; G. Traversi; S. Bettarini; G. Calderini; R. Cenci; M. Giorgi; F. Forti; F. Morsani; G. Rizzo

2006-01-01

135

Analysis of charge transport in gels containing polyoxometallates using methods of different sensitivity to migration.  

PubMed

Two methods have been used for examination of transport of charge in gels soaked with DMF and containing dissolved polyoxometallates. The first method is based on the analysis of both Cottrellian and steady-state currents and therefore is capable of giving the concentration of the electroactive redox centres and their transport (diffusion-type) coefficient. The second method provides the real diffusion coefficients, i.e. transport coefficients free of migrational influence, for both the substrate and the product of the electrode reaction. Several gels based on poly(methyl methacrylate), with charged (addition of 1-acrylamido-2-methyl-2-propanesulphonic acid to the polymerization mixture) and uncharged chains, have been used in the investigation. The ratio obtained for the diffusion coefficient (second method) and transport coefficient (first method) was smaller for the gels containing charged polymer chains than for the gels with uncharged chains. In part these changes could be explained by the contribution of migration to the transport of polyoxomatallates in the gels. However, the impact of the changes in the polymer-channel capacity at the electrode surface while the electrode process proceeds was also considered. These structural changes should affect differently the methods based on different time domains. PMID:17723584

Caban, Karolina; Lewera, Adam; Zukowska, Grazyna Z; Kulesza, Pawel J; Stojek, Zbigniew; Jeffrey, Kenneth R

2006-05-27

136

Transmitters using Power Amplifiers  

Microsoft Academic Search

TWT amplifiers have traditionally been used for microwave communications links requiring high power amplifiers. The mean-time-before-failure (MTBF) of traveling wave tube amplifiers (TWTAs) is low compared to solid state power amplifiers and generally limits the communication system performance. The frequency and power capabilities of solid state amplifiers using FETs and IMPATT devices have been advancing rapidly in recent years. Transmitters

J. Goel; S. Yuan

1984-01-01

137

Quantum limits on probabilistic amplifiers  

NASA Astrophysics Data System (ADS)

An ideal phase-preserving linear amplifier is a deterministic device that adds to an input signal the minimal amount of noise consistent with the constraints imposed by quantum mechanics. A noiseless linear amplifier takes an input coherent state to an amplified coherent state, but only works part of the time. Such a device is actually better than noiseless, since the output has less noise than the amplified noise of the input coherent state; for this reason we refer to such devices as immaculate. Here we bound the working probabilities of probabilistic and approximate immaculate amplifiers and construct theoretical models that achieve some of these bounds. Our chief conclusions are the following: (i) The working probability of any phase-insensitive immaculate amplifier is very small in the phase-plane region where the device works with high fidelity; (ii) phase-sensitive immaculate amplifiers that work only on coherent states sparsely distributed on a phase-plane circle centered at the origin can have a reasonably high working probability.

Pandey, Shashank; Jiang, Zhang; Combes, Joshua; Caves, Carlton M.

2013-09-01

138

The effect of molecular aggregates over the interfacial charge transfer processes on dye sensitized solar cells  

SciTech Connect

The electron transfer reaction between the photoinjected electrons in the nanocrystalline TiO{sub 2} mesoporous sensitized films and the oxidized electrolyte in dye sensitized solar cells (DSSC) plays a major role on the device efficiency. In this communication we show that, although the presence of molecular aggregates on the free base porphyrin DSSC limits the device photocurrent response under illumination, they form an effective hydrophobic barrier against the oxidized electrolyte impeding fast back-electron transfer kinetics. Therefore, their drawback can be overcome by designing dyes with peripheral moieties that prevent the formation of the aggregates and are able to achieve efficiencies as high as 3.2% under full sun.

Planells, Miquel; Forneli, Amparo; Martinez-Ferrero, Eugenia; Sanchez-Diaz, Antonio; Sarmentero, Maria Angeles [Institute of Chemical Research of Catalonia (ICIQ). Avda. Paiesos Catalans, 16 Tarragona 43007 (Spain); Ballester, Pablo; Palomares, Emilio [Institute of Chemical Research of Catalonia (ICIQ). Avda. Paiesos Catalans, 16 Tarragona 43007 (Spain); Institucio Catalana de Recerca i Estudis Avancats (ICREA), Passeig Lluis Companys, 23 08010 Barcelona (Spain); O'Regan, Brian C. [Centre for Electronic Materials and Devices, Imperial College of London, Exhibition Road, SW7 2AZ London (United Kingdom)

2008-04-14

139

Detection of non-absorbing charge dynamics via refractive index change in dye-sensitized solar cells.  

PubMed

The carrier dynamics in dye-sensitized solar cells was investigated by using the transient grating, in addition to the transient absorption method and transient photocurrent method on the order of microseconds to seconds. The signals for the same sample were obtained under a short-circuit condition to compare the carrier dynamics via refractive index change with the transient photocurrent measurement. Optically silent carrier dynamics by transient absorption have been successfully observed via a refractive index change. The corresponding signal components were originated from the charge dynamics at the solid/liquid interface, especially on the liquid side; rearrangement or diffusion motion of charged redox species occurred when the injected electrons were trapped at the TiO2 surface and when the electron-electrolyte recombination occurred at the interface. The assignments were confirmed from the dependence on the viscosity of the solvent and the presence of 4-tert-butyl pyridine. As the viscosity of the solvent increased, the rearrangement and the motion of the charged redox species were delayed. Since the rearrangement dynamics was changed by the presence of 4-tert-butyl pyridine, it affected not only the TiO2 surface but also the redox species close to the interface. PMID:23493913

Kuwahara, Shota; Hata, Hiroaki; Taya, Soichiro; Maeda, Naotaka; Shen, Qing; Toyoda, Taro; Katayama, Kenji

2013-03-15

140

Compton Versterker (Compton Amplifier).  

National Technical Information Service (NTIS)

The broad wave amplifier was developed to amplify signals from Compton detectors, which are part of the security system for the MEA (Medium Energy Accelerator) linear amplifier in Amsterdam. Compton detectors determine the position of the electrons in the...

J. T. van Es J. C. Verkooijen

1989-01-01

141

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

PubMed

Molecular modification is certified as a powerful strategy to adjust the energy alignment and electron transfer dynamics of dye-sensitized solar cells (DSCs). Herein, devices are assembled with three robust solvent (3-methoxypropionitrile, N,N-dimethylformamide and ?-butyrolactone) based electrolytes to elucidate the solvent dipole effects at the semiconductor-dye-electrolyte interface. Photovoltaic results demonstrate that open-circuit photovoltages of the devices vary linearly with the dipole moment of the solvents, along with an adverse dependence of the short-circuit photocurrent density under simulated irradiation. Impedance analysis reveals an apparent dipole moment-modulated conduction band edge shift of the nanocrystalline TiO(2) electrodes with respect to the redox potential of the electrolyte. Furthermore, the adverse shifts of the short-circuit photocurrent are explained by a dipole dependence of the driving force for electron injection and the interfacial charge recombination, together with a notably changed charge collection efficiency. Therefore, this study draws attention to the feasibility of tuning the electron transfer dynamics and energy alignment in photoelectrochemical devices by judiciously selecting the electrolyte solvents for further efficiency improvement, especially for those alternative organic sensitizers or quantum dots with inadequate electron injection driven forces. PMID:23223876

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

2012-12-10

142

Switchable auto gain amplifier  

DOEpatents

This invention is comprised of a switchable auto gain amplifier system for amplifying electrical signals of unknown magnitude has a plurality of amplifiers having different gains, each amplifier having an input connected to a system input. A switch controllably directs only one of the amplifier outputs to a system output. The switch is controlled by comparators providing an electrical outputs indicating each saturated amplifier. 2 figs.

Boye, C.A.; Phipps, G.S.; Schaefer, J.P.

1988-10-21

143

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

NASA Astrophysics Data System (ADS)

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.

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

2007-10-01

144

Applications of position sensitive germanium detectors for X-ray spectroscopy of highly charged heavy ions  

Microsoft Academic Search

The spectroscopy of atomic transitions in the hard X-ray regime above 15 keV utilizing position-sensitive solid state detectors is discussed. Special emphasis is given to the current detector developments for X-ray spectroscopy of heavy ions at the ESR storage ring where applications for precision spectroscopy as well as for polarization studies are of particular interest. For both cases, the advantages

Th. Stöhlker; D. Banas; H. F Beyer; A. Gumberidze; C. Kozhuharov; E. Kanter; T. Krings; W. Lewoczko; X. Ma; D. Protic; D. Sierpowski; U. Spillmann; S. Tachenov; A. Warczak

2003-01-01

145

A high temperature precision amplifier  

SciTech Connect

A precision operational amplifier has been developed for instrumentation applications in which the circuitry must operate in ambient temperatures as high as 200 C. At 200 C the amplifier maintains an input offset voltage and current of less than 200 {mu}V and 1 nA respectively, a gain bandwidth product of 2.2 MHz, and a slew rate of 5.4 V/{mu}S. The amplifier is fabricated in a standard CMOS process and consumes 5.5 mW of power at a supply voltage of 5 V. A continuous time auto-zeroed amplifier topology is used to achieve the low offset voltage levels. At high temperatures the leakage currents of the sample and hold switches used to achieve auto-zeroing degrade the offset correction voltages stored on the hold capacitors. This degradation is reduced by using large external hold capacitors and by minimizing the diffusion area of the switches through the use of a doughnut shaped layout. The effect of the voltage degradation is reduced by sensing the offset correction voltage with a low sensitivity differential auxiliary input stage. A new input switch topology is used to reduce the amplifier`s input offset current at high temperatures.

Finvers, I.G.; Haslett, J.W.; Trofimenkoff, F.N. [Univ. of Calgary, Alberta (Canada). Dept. of Electrical and Computer Engineering

1995-02-01

146

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

NASA Astrophysics Data System (ADS)

Dye sensitized solar cells (DSSCs) offer the potential of being low-cost, high-efficiency photovoltaic devices. However, the power conversion efficiency is limited as they cannot utilize all photons of the visible solar spectrum. A novel design of a core-shell photoanode is presented herein where a thin shell of infrared dye is deposited over the core of a sensitized TiO2 nanofiber. Specifically, a ruthenium based dye (N719) sensitized TiO2 nanofiber is wrapped by a thin shell of copper phthalocyanine (CuPc). In addition to broadening the absorption spectrum, this core-shell configuration further suppresses the electron-hole recombination process. Instead of adopting the typical Förster resonance energy transfer, upon photons being absorbed by the infrared dye, electrons are transferred efficiently through a cascade process from the CuPc to the N719 dye, the conduction band of TiO2, the FTO electrode and finally the external circuit. Concurrently, photons are also absorbed by the N719 dye with electrons being transferred in the cell. These additive effects result in a high power conversion efficiency of 9.48% for the device. The proposed strategy provides an alternative method for enhancing the performance of DSSCs for low-cost renewable energy in the future.Dye sensitized solar cells (DSSCs) offer the potential of being low-cost, high-efficiency photovoltaic devices. However, the power conversion efficiency is limited as they cannot utilize all photons of the visible solar spectrum. A novel design of a core-shell photoanode is presented herein where a thin shell of infrared dye is deposited over the core of a sensitized TiO2 nanofiber. Specifically, a ruthenium based dye (N719) sensitized TiO2 nanofiber is wrapped by a thin shell of copper phthalocyanine (CuPc). In addition to broadening the absorption spectrum, this core-shell configuration further suppresses the electron-hole recombination process. Instead of adopting the typical Förster resonance energy transfer, upon photons being absorbed by the infrared dye, electrons are transferred efficiently through a cascade process from the CuPc to the N719 dye, the conduction band of TiO2, the FTO electrode and finally the external circuit. Concurrently, photons are also absorbed by the N719 dye with electrons being transferred in the cell. These additive effects result in a high power conversion efficiency of 9.48% for the device. The proposed strategy provides an alternative method for enhancing the performance of DSSCs for low-cost renewable energy in the future. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01868g

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

2013-07-01

147

Halogen bonding--a key step in charge recombination of the dye-sensitized solar cell.  

PubMed

The halogen bonding between [Ru(dcbpy)(2)(SCN)(2)] dye and I(2) molecule has been studied. The ruthenium complex forms a stable [Ru(dcbpy)(2)(SCN)(2)]···I(2)·4(CH(3)OH) adduct via S···I interaction between the thiocyanate ligand and the I(2) molecule. The adduct can be seen as a model for one of the key intermediates in the regeneration cycle of the oxidized dye by the I(-)/I(3)(-) electrolyte in dye sensitized solar cells. PMID:21390388

Tuikka, Matti; Hirva, Pipsa; Rissanen, Kari; Korppi-Tommola, Jouko; Haukka, Matti

2011-03-10

148

Highly Sensitive Determination of the Polaron-Induced Optical Absorption of Organic Charge-Transport Materials  

NASA Astrophysics Data System (ADS)

We examine polaron-induced absorption in organic transport materials using a highly sensitive measurement technique. A hole only device is embedded into a low-loss TE2 waveguide structure, and the current induced change of the waveguide absorption is measured. The exemplary study of 2,2',7,7'-tetrakis(N,N-diphenylamine)-9,9'-spiro-bifluorene (S-TAD) reveals a very low polaron absorption cross section of ?p?2.6×10-18cm2 for 560 nm ???660nm. The accuracy of this data is unsurpassed by other techniques used for the unambiguous study of polaronic species in organic thin films.

Rabe, T.; Görrn, P.; Lehnhardt, M.; Tilgner, M.; Riedl, T.; Kowalsky, W.

2009-04-01

149

Sensitivity of Thermonuclear Burn to Charged Particle Stopping Power Models in NIF-like Targets  

NASA Astrophysics Data System (ADS)

Accurate treatment of fusion product charged particle transport (in particular the 3.5 MeV alpha particles) is very important for the accurate simulation of ICF ignition, bootstrap heating and burn. Models have been proposed by many authors to account for collisional scattering, dielectric scattering, degeneracy effect, and combined collisional-dielectric behavior. We present 1D calculations comparing the behavior of NIF ignition-like targets for a series of different stopping power models. As each of these models has complicated validity constraints, we keep track of validity violations in terms of the amount of energy deposited while using a theoretically invalid stopping power. For our calculations we use the radiation-hydrodynamics code BUCKY and have developed a stopping power library: Deeks. Deeks implements the stopping power models of Landau; Spitzer; Li and Petrasso; Brown, Preston and Singleton; Kihara and Aono; May and Cramer; Brysk; Skupsky; and a degenerate extension of Li and Petrasso's model in the library Deeks. Additionally, Deeks can mix electron and ion components of different models while retaining validity checks for the hybrid model.

Terry, Matthew; Moses, Gregory

2009-11-01

150

Design of linear transimpedance amplifiers  

Microsoft Academic Search

Current-to-voltage converters are important building blocks in analog-mixed signal processing circuits. In this paper, two very simple circuits of transimpedance amplifier used to realize a linear current-to-voltage conversion are presented. The circuits operation is not based on any charge accumulation process and the implementation of the circuits does not require any linear capacitance. The gain of the conversion and the

Chunyan Wang; Jiqiang Wang

2001-01-01

151

SQUARE WAVE AMPLIFIER  

DOEpatents

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

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

1958-08-01

152

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

SciTech Connect

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.

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

153

DFT-INDO/S modeling of new high molar extinction coefficient charge-transfer sensitizers for solar cell applications.  

PubMed

A new ruthenium(II) complex, tetrabutylammonium [ruthenium (4-carboxylic acid-4'-carboxylate-2,2'-bipyridine)(4,4'-di(2-(3,6-dimethoxyphenyl)ethenyl)-2,2'-bipyridine)(NCS)(2)] (N945H), was synthesized and characterized by analytical, spectroscopic, and electrochemical techniques. The absorption spectrum of the N945H sensitizer is dominated by metal-to-ligand charge-transfer (MLCT) transitions in the visible region, with the lowest allowed MLCT bands appearing at 25 380 and 18 180 cm(-1). The molar extinction coefficients of these bands are 34 500 and 18 900 M(-1) cm(-1), respectively, and are significantly higher when compared to than those of the standard sensitizer cis-dithiocyanatobis(4,4'-dicarboxylic acid-2,2'-bipyridine)ruthenium(II). An INDO/S and density functional theory study of the electronic and optical properties of N945H and of N945 adsorbed on TiO(2) was performed. The calculations point out that the top three frontier-filled orbitals have essentially ruthenium 4d (t(2g) in the octahedral group) character with sizable contribution coming from the NCS ligand orbitals. Most critically the calculations reveal that, in the TiO(2)-bound N945 sensitizer, excitation directs charge into the carboxylbipyridine ligand bound to the TiO(2) surface. The photovoltaic data of the N945 sensitizer using an electrolyte containing 0.60 M butylmethylimidazolium iodide, 0.03 M I(2), 0.10 M guanidinium thiocyanate, and 0.50 M tert-butylpyridine in a mixture of acetonitrile and valeronitrile (volume ratio = 85:15) exhibited a short-circuit photocurrent density of 16.50 +/- 0.2 mA cm(-2), an open-circuit voltage of 790 +/- 30 mV, and a fill factor of 0.72 +/- 0.03, corresponding to an overall conversion efficiency of 9.6% under standard AM (air mass) 1.5 sunlight, and demonstrated a stable performance under light and heat soaking at 80 degrees C. PMID:16411715

Nazeeruddin, Mohammad K; Wang, Qing; Cevey, Le; Aranyos, Viviane; Liska, Paul; Figgemeier, Egbert; Klein, Cedric; Hirata, Narukuni; Koops, Sara; Haque, Saif A; Durrant, James R; Hagfeldt, Anders; Lever, A B P; Grätzel, Michael

2006-01-23

154

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

SciTech Connect

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.

Cho, Gyuseong

1992-03-01

155

Segmented amplifier configurations for laser amplifier  

DOEpatents

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

Hagen, Wilhelm F. (Livermore, CA)

1979-01-01

156

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

157

Hybrid matrix amplifier  

DOEpatents

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

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

1995-01-03

158

Hybrid matrix amplifier  

DOEpatents

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

Martens, Jon S. (Sunnyvale, CA); Hietala, Vincent M. (Placitas, NM); Plut, Thomas A. (Albuquerque, NM)

1995-01-01

159

Innovative current sensitive differential low noise preamplifier in CMOS  

Microsoft Academic Search

A low noise differential preamplifier is described. A novel circuit is introduced, reducing the 2nd stage noise contribution of a conventional current mirror fed from the differential input stage to negligible amounts by employing a differential cascode. A desirable by-product of the modified circuit is its increased PSRR. The output of the charge sensitive voltage amplifier employed as low noise

Arie Arbel

1996-01-01

160

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

Microsoft Academic Search

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”

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

2009-01-01

161

On the choice of optimum FET size in wide-band transimpedance amplifiers  

Microsoft Academic Search

The main figure of merit for transimpedance amplifiers used in amplifying photocurrents in fiber-optics systems is the optical sensitivity. This sensitivity is determined by the equivalent input noise current of the amplifier. To obtain the best noise performance, most transimpedance amplifiers with FET input stages are designed using a result that prescribes making the capacitance of the input FET equal

A. A. Abidi

1988-01-01

162

Progress on diamond amplified photo-cathode  

SciTech Connect

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.

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

2011-03-28

163

Portable musical instrument amplifier  

SciTech Connect

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

Christian, David E. (Danbury, CT)

1990-07-24

164

Portable musical instrument amplifier  

DOEpatents

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

Christian, David E. (Danbury, CT)

1990-07-24

165

Sensitive analysis of donepezil in plasma by capillary electrophoresis combining on-column field-amplified sample stacking and its application in Alzheimer's disease.  

PubMed

Field-amplified sample stacking (FASS) in capillary electrophoresis (CE) was used to determine the concentration of donepezil, an acetylcholinesterase inhibitor, in human plasma. A sample pretreatment by liquid-liquid extraction with isopropanol/n-hexane (v/v 3:97) and subsequent quantification by FASS-CE was used. Before sample loading, a water plug (0.5 psi, 6 s) was injected to permit FASS. Electrokinetic injection (7 kV, 90 s) was used to introduce sample cations. The separation condition for donepezil was performed in electrolyte solutions containing Tris buffer (60 mM, pH 4.0) with sodium octanesulfonate 40 mM and 0.01% polyvinyl alcohol as a dynamic coating to reduce analytes' interaction with capillary wall. The separation was performed at 28 kV and detected at 200 nm. Using atenolol as an internal standard, the linear ranges of the method for the determination of donepezil in human plasma were over a range of 1-50 ng/mL. The limit of detection was 0.1 ng/mL (S/N=3, sampling 90 s at 7 kV). One female volunteer (54 years old) was orally administered a single dose of 10 mg donepezil (Aricept, Eisai), and blood samples were drawn over a 60 h period for pharmacokinetic study. The method was also applied successfully to monitor donepezil in sixteen Alzheimer's disease patients' plasmas. PMID:18803179

Yeh, Hsin-Hua; Yang, Yuan-Han; Ko, Ju-Yun; Chen, Su-Hwei

2008-09-01

166

Exploring the bond topological properties and the charge depletion-impact sensitivity relationship of high energetic TNT molecule via theoretical charge density analysis  

Microsoft Academic Search

To understand the energetic properties of 2,3,4-Trinitrotolune (TNT) molecule, a quantum chemical calculation and the electronic charge density analysis have been performed. The density functional theory (B3P86\\/6-311G??) calculation was carried out using Gaussian03 software. The energy-minimized wave function obtained from DFT was used for the charge density analysis. The inductive and steric effects of methyl and nitro substituents are not

Arputharaj David Stephen; Rajesh B. Pawar; Poomani Kumaradhas

2010-01-01

167

Nanosecond Spectrometric Amplifier.  

National Technical Information Service (NTIS)

Nanosecond amplifier intended for operation together with spectrometric amplifiers under conditions of high and changing-in-time loads is described. Zero drift at the amplifier output is <= 200 mu V/C exp 0 . Output pulse rise time equals 3 ns at 25 Ohm l...

G. B. Dzyubenko

1981-01-01

168

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

SciTech Connect

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

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

2012-03-12

169

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

PubMed Central

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

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

2009-01-01

170

Systematic Prediction of Dyes for Dye Sensitized Solar Cells: Data-mining via Molecular Charge-Transfer Algorithms  

NASA Astrophysics Data System (ADS)

Graph theoretical algorithms and classification tests are combined with data-mining tools to present successful predictions of high-performance dyes for dye-sensitized solar cells (DSCs). The construction of molecular charge-transfer algorithms is described, featuring recursive depth-first, back-tracking, graph traversal algorithms with classification test formalisms. These algorithms are employed to search through a representative set of organic chemical space (120,000 chemical molecules) to identify compounds that have the required structural attributes to act as high-performance dyes for DSCs. The first results of these predictions are validated by comparison of the predicted structural motifs to existing well-known dyes that are currently in use for DSC device application. Three chemical motifs are shown to form the chemical back-bone of three popular dyes, thereby validating the predictions. Further work is described which includes the DSC fabrication and testing of the new classes of unknown dye; this pertains to the ultimate goal of systematic design of new dyes for DSC device application.

Cole, Jacqueline M.

2011-09-01

171

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

PubMed

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

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

2013-10-01

172

Signal and noise performance of large-area PIN photodiodes and charge-sensitive preamplifiers for gamma radiography  

NASA Astrophysics Data System (ADS)

Using 5 cm long CsI (Tl) crystal scintillators, large-area PIN-type photodiodes of 1 cm×1 cm, and a low-noise charge-sensitive preamplifier, two gamma-ray detectors were manufactured. One detector used PIN-type photodiodes fabricated in the process of Electronics and Telecommunications Research Institute (ETRI) and the other one was based on Hamamatsu PIN-type photodiodes of S-3590-01. Gamma spectroscopies were performed and analyzed for both Co-60 and Cs-137 gamma sources. The first detector showed energy resolutions (FWHM) of 6.4% and 5.5% for 1.17 and 1.33 MeV, which were similar to energy resolutions of the second detector for Co-60, but the second detector showed 6.6% better resolution than the first detector's 11.8% for Cs-137. For 10 h exposure of Co-60 (14.5 ?Ci), noise equivalent quanta (NEQ) and spectroscopy for both detectors have been investigated in detail. The NEQ of 25% increased after the exposure and degradations of the FWHMs of 26% and 11% have been found for 1.17 and 1.33 MeV, respectively.

Kim, Kwang Hyun; Kim, Young Soo; Kim, Jung Soo

2008-06-01

173

Laser amplifier chain  

DOEpatents

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

Hackel, Richard P. (Livermore, CA)

1992-01-01

174

Low noise tuned amplifier  

NASA Astrophysics Data System (ADS)

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

Kleinberg, L. L.

1984-03-01

175

Measurement of Electric Charge of Dust Particles in a Plasma  

NASA Astrophysics Data System (ADS)

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.

Itoh, Masataka; Nakamura, Yoshiharu

2000-10-01

176

Primer on the Lock-in Amplifier  

NSDL National Science Digital Library

This is an experiment designed to measure the resistance of copper and gold nanowires using a lock-in amplifier. Students learn: 1. about different types of noise, 2. the principles of phase-sensitive techniques, 3. to extract signals buried in noise using a lock-in amplifier, 4. to operate optical chopper to measure weak optical signals modulated at a certain frequency. 4. to measure the minute resistance of a conducting nanowires.

Farooq, Sidra; Salman, Rabiya; Zia, Wasif; Hassan, Umer; Anwar, Muhammad S.

2012-02-10

177

UHF Integrated Power Amplifiers  

Microsoft Academic Search

This paper describes the development of integrated UHF power amplifiers using thin-film lumped elements and UHF power-transistor chips. Single-stage hybrid amplifier modules capable of delivering output powers up to 20 watts CW in the frequency range of 225-400 MHz are reported. In addition, broad-band hybrid amplifiers are discussed with 1-dB bandwidths of up to 40 percent in the same 225-400

W. E. Poole

1969-01-01

178

Space charge effects in polymer-based light-emitting diodes studied by means of a polarization sensitive electroreflectance technique  

NASA Astrophysics Data System (ADS)

We used a single wavelength electro-optical reflection technique to study the creation of space charge distributions in a polymer light emitting diode, by monitoring the real third order nonlinear optical response of the electroluminescent layer. The diode is based on an aluminum/polymer/indium tin oxide stack, where the polymer is a derivative of poly(p-phenylene-vinylene) in which oxidiazole groups were grafted as side chains. The measured signal is strongly influenced by a space charge distribution and by screening in the organic layer. The space charge distribution is the superposition of a long lived contribution, close to indium tin oxide, due to charges trapped in deep levels, and of that of relatively mobile charges injected in the polymer film. In the frame of a model which takes into account Debye-Hückel screening, with screening length equal to 100 nm we estimated the carrier density of the long lived charge distribution to be 4.8×1023 m-3, for a uniform distribution in a 110-nm-thick layer. The influence of the injection of mobile charges on the electro-optic signal is an order of magnitude smaller than that of trapped charges. The real third order susceptibility of the polymer is estimated to be ?(3)=4×10-21 m2/V2.

Michelotti, F.; Bussi, S.; Dominici, L.; Bertolotti, M.; Bao, Z.

2002-05-01

179

Amplifiers and Active Systems  

NSDL National Science Digital Library

Created by Tony R. Kuphaldt, this chapter of All About Circuit's third volume on Semiconductors describes amplifiers and active devices. The chapter is divided into seven sections: From electric to electronic, Active versus passive devices, Amplifiers, Amplifier gain, Decibels, Absolute dB scales, and Attenuators. Each section has clear illustrations and a concise, bulleted review of what was covered at the end. There is also a link to the All About Circuits forums, where contributors and other visitors discuss the material presented. This is an excellent resource for educators in physics and electronic engineering classrooms to introduce lessons or units on amplifiers.

Kuphaldt, Tony R.

2008-07-03

180

Compact laser amplifier system  

DOEpatents

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

Carr, R.B.

1974-02-26

181

Electron donor-acceptor distance dependence of the dynamics of light-induced interfacial charge transfer in the dye-sensitization of nanocrystalline oxide semiconductors  

Microsoft Academic Search

The effect of electronic and nuclear factors on the dynamics of dye-to-semiconductor electron transfer was studied employing RuII(terpy)(NCS)3 sensitizers grafted onto transparent films made of titanium dioxide nanoparticles. Various approaches were strived to understand the dependence of the kinetics of charge injection and recombination processes upon the distance separating the dye molecules and the redox active surface. A series of

Bernard Wenger; Christophe Bauer; Mohammad K. Nazeeruddin; Pascal Comte; Shaik M. Zakeeruddin; Michael Grätzel; Jacques-E. Moser

2006-01-01

182

Effect of Electrostatic Interactions on the Binding of Charged Substrate to GroEL Studied by Highly Sensitive Fluorescence Correlation Spectroscopy  

Microsoft Academic Search

The binding processes of GroEL with apo cytochrome c (apo-cyt c) and disulfide-reduced apo ?-lactalbumin (rLA) in homogeneous solution at low concentration were analyzed by fluorescence correlation spectroscopy (FCS) with extremely high sensitivity. Although apo-cyt c, a positively charged substrate, was tightly bound to GroEL in both the absence and the presence of 200 mM KCl, the strength of the

Chan-Gi Pack; Katsuhiko Aoki; Hideki Taguchi; Masasuke Yoshida; Masataka Kinjo; Mamoru Tamura

2000-01-01

183

Direct measurement of product of the electron mobility and mean free drift time of CdZnTe semiconductors using position sensitive single polarity charge sensing detectors  

NASA Astrophysics Data System (ADS)

This article describes novel techniques to directly measure the electron mobility and mean free drift time product ?e?e in semiconductor detectors. These methods are based on newly developed single polarity charge sensing and depth sensing techniques. Compared with conventional methods based on the Hecht relation, the new methods do not involve curve fitting, are less sensitive to the variation of pulse rise times, and allow the use of higher energy ? rays typical of many applications.

He, Z.; Knoll, G. F.; Wehe, D. K.

1998-11-01

184

Note: A high dynamic range, linear response transimpedance amplifier  

NASA Astrophysics Data System (ADS)

We have built a high dynamic range (nine decade) transimpedance amplifier with a linear response. The amplifier uses junction-gate field effect transistors (JFETs) to switch between three different resistors in the feedback of a low input bias current operational amplifier. This allows for the creation of multiple outputs, each with a linear response and a different transimpedance gain. The overall bandwidth of the transimpedance amplifier is set by the bandwidth of the most sensitive range. For our application, we demonstrate a three-stage amplifier with transimpedance gains of approximately 109?, 3 × 107?, and 104? with a bandwidth of 100 Hz.

Eckel, S.; Sushkov, A. O.; Lamoreaux, S. K.

2012-02-01

185

Note: A high dynamic range, linear response transimpedance amplifier.  

PubMed

We have built a high dynamic range (nine decade) transimpedance amplifier with a linear response. The amplifier uses junction-gate field effect transistors (JFETs) to switch between three different resistors in the feedback of a low input bias current operational amplifier. This allows for the creation of multiple outputs, each with a linear response and a different transimpedance gain. The overall bandwidth of the transimpedance amplifier is set by the bandwidth of the most sensitive range. For our application, we demonstrate a three-stage amplifier with transimpedance gains of approximately 10(9)?, 3 × 10(7)?, and 10(4)? with a bandwidth of 100 Hz. PMID:22380140

Eckel, S; Sushkov, A O; Lamoreaux, S K

2012-02-01

186

Silicon Evanescent Amplifiers  

Microsoft Academic Search

Optical amplifiers are important elements of photonic integrated circuits. We present a hybrid silicon evanescent amplifier utilizing a wafer bonded structure of silicon waveguide and AlGaInAs quantum wells. A chip gain of 13 dB with a power penalty of 0.5 dB at 40 Gb\\/s data amplification is demonstrated.

J. E. Bowers; Ying-hao Kuo; A. W. Fang; R. Jones; M. J. Paniccia; O. Cohen; O. Raday

2007-01-01

187

Antares laser power amplifier  

Microsoft Academic Search

The design of the Antares laser power amplifier is discussed. The power amplifier is the last stage of amplification in the 100 kJ Antares laser. A single, cylindrical, grid control, cold cathode electron gun, surrounded by 12 large aperture CO2 electron beam sustained laser discharge sectors is described. A large scale interaction between optical, mechanical, and electrical disciplines required to

R. D. Stine; G. F. Ross; C. J. Silvernail

1979-01-01

188

Dye laser amplifier  

DOEpatents

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

Moses, E.I.

1992-12-01

189

Excitron-laser amplifier  

NASA Astrophysics Data System (ADS)

A laser-amplifying device is described which is based on the stimulated decay of excitons in a pure crystal. An estimate is made of the gain of the device. At a typical frequency the gain is found to be appreciably large thus suggesting practical application of the laser amplifier.

Liboff, R. L.; Liu, K. C.

1982-12-01

190

Controlling the directionality of charge transfer in phthalocyaninato zinc sensitizer for a dye-sensitized solar cell: density functional theory studies.  

PubMed

Density functional theory (DFT) calculation on the molecular structures, charge distribution, molecular orbitals, electronic absorption spectra of a series of eight unsymmetrical phthalocyaninato zinc complexes with one peripheral (E)-2-cyano-3-(5-vinylthiophen-2-yl) acrylic acid substituent at 2 or 3 position as an electron-withdrawing group and a different number of electron-donating amino groups at the remaining peripheral positions (9, 10, 16, 17, 23, 24) of the phthalocyanine ring, namely ZnPc-?-A, ZnPc-?-A-I-NH(2), ZnPc-?-A-II-NH(2), ZnPc-?-A-III-NH(2), ZnPc-?-A-I,II-NH(2), ZnPc-?-A-I,III-NH(2), ZnPc-?-A-II,III-NH(2), and ZnPc-?-A-I,II,III-NH(2), reveals the effects of amino groups on the charge transfer properties of these phthalocyanine derivatives with a typical D-?-A electronic structure. The introduction of amino groups was revealed altering of the atomic charge distribution, lifting the frontier molecular orbital level, red-shift of the near-IR bands in the electronic absorption spectra, and finally resulting in enhanced charge transfer directionality for the phthalocyanine compounds. Along with the increase of the peripheral amino groups at the phthalocyanine ring from 0, 2, 4, to 6, the dihedral angle between the phthalocyanine ring and the average plane of the (E)-2-cyano-3-(5-vinylthiophen-2-yl) acrylic acid substituent increases from 0 to 3.3° in an irregular manner. This is in good contrast to the regular and significant change in the charge distribution, destabilization of frontier orbital energies, and red shift of near-IR bands of phthalocyanine compounds along the same order. In addition, comparative studies indicate the smaller effect of incorporating two amino groups onto the 16 and 17 than on 9 and 10 or 23 and 24 peripheral positions of the phthalocyanine ring onto the aforementioned electronic properties, suggesting the least effect on tuning the charge transfer property of the phthalocyanine compound via introducing two electron-donating amino groups onto the 16 and 17 peripheral positions. As expected, compound ZnPc-?-A-I,III-NH(2) with four amino groups at 9, 10, 23, and 24 positions of the phthalocyanine ring shows the best charge transfer directionality among the three phthalocyaninato zinc complexes with four peripheral amino groups. PMID:21103486

Wan, Liang; Qi, Dongdong; Zhang, Yuexing; Jiang, Jianzhuang

2010-11-22

191

Josephson bifurcation amplifier: Amplifying quantum signals using a dynamical bifurcation  

NASA Astrophysics Data System (ADS)

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.

Vijayaraghavan, Rajamani

192

Tuning Broadband Microwave Amplifiers  

SciTech Connect

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

Alaniz, Gabriel

2003-09-05

193

An optically isolated amplifier  

NASA Astrophysics Data System (ADS)

The design presented was used for biomedical signal detection and monitoring. The amplifier was successfully applied for EMG and ECG research studies. The patient is safely isolated from the processing equipment when using the amplifier. This opto-isolated amplifier was also applied industrially for monitoring mercury arc rectifier control signals. The device has proved itself in an industrial environment as an interface for a microprocessor. This unit can be used whenever large offset voltages are found, and can therefore be put to good use in many power electrical engineering applications.

Smith, C. J.

1982-11-01

194

Amplify Interest in STS.  

ERIC Educational Resources Information Center

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

Chiappetta, Eugene L; Mays, John D.

1992-01-01

195

Fully relayed regenerative amplifier  

DOEpatents

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

Glass, Alexander J. (Berkeley, CA)

1981-01-01

196

Reflective Type Laser Amplifier.  

National Technical Information Service (NTIS)

Calculations have been carried out in an analysis of a reflection type laser amplifier. Electromagnetic radiation is assumed to travel at normal incidence through a system composed of air, a partially transmitting silver reflector, active media such as ru...

H. Jacobs D. A. Holmes L. Hatkin F. A. Brand

1964-01-01

197

Area detector amplifier module  

Microsoft Academic Search

The objective of the design of the Area Detector Amplifier Module (ADAM) is to obtain the high frequency response of a 2.5 × 10-7 sq cm pyro-electric detector with a 2 sq cm detector. The design essentially segments the 2 sq cm pyroelectric detector into over 107 detectors, adds a separate high gain amplifier in series with each detector, and

C. M. Redman

1976-01-01

198

Amplified DNA Biosensors  

Microsoft Academic Search

\\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

Itamar Willner; Bella Shlyahovsky; Bilha Willner; Maya Zayats

2009-01-01

199

Superfunctions for amplifiers  

NASA Astrophysics Data System (ADS)

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.

Kouznetsov, Dmitrii

2013-07-01

200

Raman amplifiers for telecommunications  

Microsoft Academic Search

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

Mohammed N. Islam

2002-01-01

201

A High Speed GaAs Monolithic Transimpedance Amplifier  

Microsoft Academic Search

This paper describes the design method and test results for a novel transimpedance amplifier suitable for very high speed optical communications systems The amplifier chip is developed for four different bit rates: 188, 565, 1130, and 1500 Mb\\/s with optical sensitivities -38.5, -33, -30, dBm, respectively. The amplifier provides 2 V peak to peak output and 30 dB dynamic range.

I. Bahl; E. Griffin; W. Powell; C. Ring

1986-01-01

202

Modeling charge recombination in dye-sensitized solar cells using first-principles electron dynamics: effects of structural modification.  

PubMed

We have performed real-time excited state simulations of electron injection and charge recombination at a dye/semiconductor interface within the framework of time-dependent density functional theory (TDDFT). We found that by inserting a phenyl ring into the organic dye, the charge recombination rate is slowed down by about four times, while the injection rate keeps almost the same. This introduces a drastic increase in the energy conversion efficiency by several folds, in agreement with experimental observations. Quantum simulations thus provide a new way to understand the role of the dye's building blocks and offer new strategies to optimize individual energy transfer steps for improving the efficiency in renewable energy applications. PMID:24013694

Ma, Wei; Jiao, Yang; Meng, Sheng

2013-09-25

203

Direct measurement of product of the electron mobility and mean free drift time of CdZnTe semiconductors using position sensitive single polarity charge sensing detectors  

SciTech Connect

This article describes novel techniques to directly measure the electron mobility and mean free drift time product {mu}{sub e}{tau}{sub e} in semiconductor detectors. These methods are based on newly developed single polarity charge sensing and depth sensing techniques. Compared with conventional methods based on the Hecht relation, the new methods do not involve curve fitting, are less sensitive to the variation of pulse rise times, and allow the use of higher energy {gamma} rays typical of many applications. {copyright} {ital 1998 American Institute of Physics.}

He, Z.; Knoll, G.F.; Wehe, D.K. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States)

1998-11-01

204

Charge site mass spectra: conformation-sensitive components of the electron capture dissociation spectrum of a protein.  

PubMed

A conventional electron capture dissociation (ECD) spectrum of a protein is uniquely characteristic of the first dimension of its linear structure. This sequence information is indicated by summing the primary c (m+) and z (m+•) products of cleavage at each of its molecular ion's inter-residue bonds. For example, the ECD spectra of ubiquitin (M?+?nH)(n+) ions, n?=?7-13, provide sequence characterization of 72 of its 75 cleavage sites from 1843 ions in seven c ((1-7)+) and eight z ((1-8)+•) spectra and their respective complements. Now we find that each of these c/z spectra is itself composed of "charge site (CS)" spectra, the c (m+) or z (m+•) products of electron capture at a specific protonated basic residue. This charge site has been H-bonded to multiple other residues, producing multiple precursor ion forms; ECD at these residues yields the multiple products of that CS spectrum. Closely similar CS spectra are often formed from a range of charge states of ubiquitin and KIX ions; this indicates a common secondary conformation, but not the conventional ?-helicity postulated previously. CS spectra should provide new capabilities for comparing regional conformations of gaseous protein ions and delineating ECD fragmentation pathways. PMID:23549668

Skinner, Owen S; Breuker, Kathrin; McLafferty, Fred W

2013-04-03

205

Charge Site Mass Spectra: Conformation-Sensitive Components of the Electron Capture Dissociation Spectrum of a Protein  

NASA Astrophysics Data System (ADS)

A conventional electron capture dissociation (ECD) spectrum of a protein is uniquely characteristic of the first dimension of its linear structure. This sequence information is indicated by summing the primary c m+ and z m+• products of cleavage at each of its molecular ion's inter-residue bonds. For example, the ECD spectra of ubiquitin (M + nH)n+ ions, n = 7-13, provide sequence characterization of 72 of its 75 cleavage sites from 1843 ions in seven c (1-7)+ and eight z (1-8)+• spectra and their respective complements. Now we find that each of these c/z spectra is itself composed of "charge site (CS)" spectra, the c m+ or z m+• products of electron capture at a specific protonated basic residue. This charge site has been H-bonded to multiple other residues, producing multiple precursor ion forms; ECD at these residues yields the multiple products of that CS spectrum. Closely similar CS spectra are often formed from a range of charge states of ubiquitin and KIX ions; this indicates a common secondary conformation, but not the conventional ?-helicity postulated previously. CS spectra should provide new capabilities for comparing regional conformations of gaseous protein ions and delineating ECD fragmentation pathways.

Skinner, Owen S.; Breuker, Kathrin; McLafferty, Fred W.

2013-06-01

206

Laser amplifier and method  

DOEpatents

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

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

1997-07-01

207

Amplified DNA Biosensors  

NASA Astrophysics Data System (ADS)

Amplified detection of DNA is a central research topic in modern bioanalytical science. Electronic or optical transduction of DNA recognition events provides readout signals for DNA biosensors. Amplification of the DNA analysis is accomplished by the coupling of nucleic acid-functionalized enzymes or nucleic acid-functionalized nanoparticles (NP) as labels for the DNA duplex formation. This chapter discusses the amplified amperometric analysis of DNA by redox enzymes, the amplified optical sensing of DNA by enzymes or DNAzymes, and the amplified voltammetric, optical, or microgravimetric analysis of DNA using metallic or semiconductor nanoparticles. Further approaches to amplify DNA detection involve the use of micro-carriers of redox compounds as labels for DNA complex formation on electrodes, or the use of micro-objects such as liposomes, that label the resulting DNA complexes on electrodes and alter the interfacial properties of the electrodes. Finally, DNA machines are used for the optical detection of DNA, and the systems are suggested as future analytical procedures that could substitute the polymerase chain reaction (PCR) process.

Willner, Itamar; Shlyahovsky, Bella; Willner, Bilha; Zayats, Maya

208

Efficient power amplifiers for piezoelectric applications  

NASA Astrophysics Data System (ADS)

The principal obstacle to greater utilization of piezoelectric actuators in aerospace applications is the extreme inefficiency and heat rejection requirements of the driving electronics. The purpose of this investigation is to take a critical look at how amplifiers for piezoelectric systems are designed and to look for potential areas for improvement. A dimensional analysis of a piezoelectric actuator is performed that indicates that power consumption in an unloaded actuator is extremely low, placing the blame for the exorbitant power demands squarely on the driving electronics. Several strategies for power savings in piezoelectric driving electronics are presented including pulse width modulation, discrete charge control, and a hybrid charge-recovery strategy.

Main, John A.; Newton, David V.; Massengill, Lloyd; Garcia, Ephrahim

1996-12-01

209

Amplified DNA in Streptomyces fradiae.  

PubMed Central

A spontaneous mutant of Streptomyces fradiae contained an amplifiable unit of DNA with a sequence length of approximately 10.5 kilobases that was amplified to approximately 500 copies per chromosome. The amplified DNA appears to be cryptic. SalI fragments of the amplified DNA were cloned into Escherichia coli to construct a restriction map and characterize the amplified DNA. The amplified DNA contained tandem repeats of the amplifiable unit of DNA. The unit had an average base composition of 71% guanine plus cytosine, similar to the chromosomal DNA of Streptomyces species. At least a portion of the amplifiable unit of DNA was present at a low copy number in the wild-type strain. The phenotype of amplified DNA was designated Ads1SF for amplified DNA sequence 1 in S. fradiae. Images

Fishman, S E; Hershberger, C L

1983-01-01

210

Effects of initial-fixed charge density on pH-sensitive hydrogels subjected to coupled pH and electric field stimuli: a meshless analysis.  

PubMed

In this paper, we study the effects of initial fixed-charge density on the response behavior of pH-sensitive hydrogels subjected to coupled stimuli, namely, solution pH and externally applied electric field. This is the first instance in which a coupled stimuli numerical analysis has been carried out for these polymer gels, which are used as active sensing/actuating elements in advanced biomicroelectromechanical systems devices. In this work, a chemo-electro-mechanical formulation, termed the multi-effect-coupling pH-stimulus (MECpH) model, is first presented. This mathematical model takes into account the ionic species diffusion, electric potential coupling, and large mechanical deformation. In addition, a correlation between the diffusive hydrogen ions and fixed-charge groups on the hydrogel polymeric chains is established based on the Langmuir absorption isotherm, and incorporated accordingly into the MECpH model. To solve the resulting highly nonlinear and highly coupled partial differential equations of this mathematical model, the Hermite-Cloud method, a novel true meshless technique, is employed. To demonstrate the accuracy and robustness the MECpH model, computed numerical results are compared with experimental data available from literature. Following this validation, several numerical studies are carried out to investigate the effects of initial fixed-charge density on the volumetric variations of these pH-stimulus-responsive hydrogels when immersed in buffered solutions. PMID:17408319

Ng, T Y; Li, Hua; Yew, Y K; Lam, K Y

2007-04-01

211

A micropower electrocardiogram amplifier.  

PubMed

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

Fay, L; Misra, V; Sarpeshkar, R

2009-10-01

212

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

SciTech Connect

A novel charged-particle sensitive, pixel based detector array is described and its usage is demonstrated for a variety of applications, from detection of elemental particles (electrons) to hyper-thermal large biomolecular positive and negative ions including keV light atomic and molecular ions. The array detector is a modified light-sensitive charged coupled device (CCD). The IonCCDTM was engineered for direct charged particle detection by replacing the semi-conductor part of the CCD pixel by a conductor1. In contrast with the CCD, where the semi-conductive pixel is responsible for electron-hole pair formation upon photon bombardment, the IonCCD uses a capacitor coupled to the conductive electrode for direct charge integration. The detector can be operated from atmospheric pressure to high vacuum since no high voltages are needed. The IonCCD, presented in this work is an array of 2126 active pixels with 21 um pixel width and 3 um pixel gap. The detection area is 1.5x51mm2 where 1.5 mm and 51 mm are pixel and detector array length, respectively. The result is a one-dimensional position-sensitive detector with 24 um spatial resolution and 88 % pixel area ratio (PAR). In this work we demonstrate the capabilities and the performance of the detector. For the first time we show the direct detection of 250 eV electrons providing linearity response and detection efficiency of the IonCCD as function of electron beam current. Using positive ions from and electron impact source (E-I), we demonstrate that the detection efficiency of the IonCCD is virtually independent of particle energy [250 eV, 1250 eV], particle impact angle [45o, 90o] and particle flux. By combining the IonCCD with a double focusing sector field of Mattauch-Herzog geometry (M-H), we demonstrate fast acquisition of mass spectra in direct air sniffing mode. A first step towards fast in vivo breath analysis is presented. Detection of hyper-thermal biomolecular ions produced using an electrospray ionization source (ESI) is presented. The IonCCD was used as beam profiler to characterize the beam shape and intensity of 15 eV protonated and deprotonated biomolecular ions at the exit of an RF only collisional quadrupole. We present simultaneous detection of 140 eV doubly protonated biomolecular ions when the IonCCD is combined with the M-H analyzer. The latter, demonstrates the possibility of simultaneous separation and micro-array deposition of biological material using a miniature sector field.

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

2011-04-01

213

Linear amplifier model for optomechanical systems  

NASA Astrophysics Data System (ADS)

We model optomechanical systems as linear optical amplifiers. This provides a unified treatment of diverse optomechanical phenomena. We emphasize, in particular, the relationship between ponderomotive squeezing and optomechanically induced transparency, two foci of current research. We characterize the amplifier response to quantum and applied classical fluctuations, both optical and mechanical. Further, we apply these results to establish quantum limits on external force sensing both on and off cavity resonance. We find that the maximum sensitivity attained on resonance constitutes an absolute upper limit, not surpassed when detuning off cavity resonance. The theory is extended to a two-sided cavity with losses and limited detection efficiency.

Botter, Thierry; Brooks, Daniel W. C.; Brahms, Nathan; Schreppler, Sydney; Stamper-Kurn, Dan M.

2012-01-01

214

Performance of a compact position-sensitive photon counting detector with image charge coupling to an air-side anode  

NASA Astrophysics Data System (ADS)

We discuss a novel micro-channel plate (MCP) photomultiplier with resistive screen (RS-PMT) as a detection device for space- and time-correlated single photon counting, illustrated by several applications. The photomultiplier tube resembles a standard image intensifier device. However, the rear phosphor screen is replaced by a ceramic "window" with resistive coating. The MCP output is transferred through the ceramic plate to the read-out electrode (on the air side) via capacity-coupling of the image charge. This design allows for an easy reconfiguration of the read-out electrode (e.g. pixel, charge-sharing, cross-strip, delay-line) without breaking the vacuum for optimizing the detector performance towards a certain task. It also eases the design and manufacturing process of such a multi-purpose photomultiplier tube. Temporal and spatial resolutions well below 100 ps and 100 microns, respectively, have been reported at event rates as high as 1 MHz, for up to 40 mm effective detection diameter. In this paper we will discuss several applications like wide-field fluorescence microscopy and dual ?/fast-neutron radiography for air cargo screening and conclude with an outlook on large-area detectors for thermal neutrons based on MCPs.

Jagutzki, O.; Czasch, A.; Schössler, S.

2013-05-01

215

Analog Electronics: Basic Circuits of Operational Amplifiers  

NSDL National Science Digital Library

This site offers a set of interactive operational amplifiers (OAs) simulators with detailed lessons and basic circuit schematics (including theory). The Java applets provided include an inverting amplifier, summing amplifier, difference amplifier, differentiator, and integrator circuit amplifier.

2009-11-02

216

Integrated front-end electronics in a detector compatible process: source-follower and charge-sensitive preamplifier configurations  

NASA Astrophysics Data System (ADS)

This study is concerned with the simulation and design of low-noise front-end electronics monolithically integrated on the same high-resistivity substrate as multielectrode silicon detectors, in a process made available by the Istituto per la Ricerca Scientifica e Tecnologica (ITC-IRST) of Trento, Italy. The integrated front-end solutions described in this paper use N-channel JFETs as basic elements. The first one is based upon an all-NJFET charge preamplifier designed to match detector capacitances of a few picofarads and available in both a resistive and a non resistive feedback configuration. In the second solution, a single NJFET in the source-follower configuration is connected to the detector, while its source is wired to an external readout channel through an integrated capacitor.

Ratti, Lodovico; Manghisoni, Massimo; Re, Valerio; Speziali, Valeria

2001-12-01

217

Effect of cholesterol and charge on pore formation in bilayer vesicles by a pH-sensitive peptide.  

PubMed Central

The effect of cholesterol on the bilayer partitioning of the peptide GALA (WEAALAEALAEALAEHLAEALAEALEALAA) and its assembly into a pore in large unilamellar vesicles composed of neutral and negatively charged phospholipids has been determined. GALA undergoes a conformational change from a random coil to an amphipathic alpha-helix when the pH is reduced from 7.0 to 5.0, inducing at low pH leakage of contents from vesicles. Leakage from neutral or negatively charged vesicles at pH 5.0 was similar and could be adequately explained by the mathematical model (Parente, R. A., S. Nir, and F. C. Szoka, Jr., 1990. Mechanism of leakage of phospholipid vesicle contents induced by the peptide GALA. Biochemistry. 29:8720-8728) which assumed that GALA becomes incorporated into the vesicle bilayer and irreversibly aggregates to form a pore consisting of 10 +/- 2 peptides. Increasing cholesterol content in the membranes resulted in a reduced efficiency of the peptide to induce leakage. Part of the cholesterol effect was due to reduced binding of the peptide to cholesterol-containing membranes. An additional effect of cholesterol was to increase reversibility of surface aggregation of the peptide in the membrane. Results could be explained and predicted with a model that retains the same pore size, i.e., 10 +/- 2 peptides, but includes reversible aggregation of the monomers to form the pore. Resonance energy transfer experiments using fluorescently labeled peptides confirmed that the degree of reversibility of surface aggregation of GALA was significantly larger in cholesterol-containing liposomes, thus reducing the efficiency of pore formation.

Nicol, F; Nir, S; Szoka, F C

1996-01-01

218

Amplifying the Optophone  

Microsoft Academic Search

MR. CAMPBELL SWINTON'S forecast in NATURE of March 3, p. 8, has been fully verified since he wrote. On Tuesday, March 1, the Marconi Co. kindly lent me one of their three-valve amplifiers working with an S. G. Brown loud-speaking telephone and wooden trumpet. Mr. F. Swann, of the Marconi Co., personally superintended the installation, and we succeeded without much

E. E. Fournier D'Albe

1921-01-01

219

High Efficiency UHF Power Amplifier.  

National Technical Information Service (NTIS)

The report describes the development and construction of an experimental High Efficiency UHF (225-400 MHz) Power Amplifier. The prime requirements for the amplifier were: 50% overall efficiency; two watt output level for 1 milliwatt input; and, operable o...

T. J. Warnagiris

1974-01-01

220

DRIFT COMPENSATED DIRECT COUPLED AMPLIFIER  

DOEpatents

An improved direct-coupled amplifier having zerolevel drift correction is described. The need for an auxiliary corrective-potential amplifier is eliminated thereby giving protection against overload saturation of the zero- level drift correcting circuit. (T.R.H.)

Windsor, A.A.

1959-05-01

221

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

NASA Astrophysics Data System (ADS)

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

Paul, Bijan Kumar; Guchhait, Nikhil

2012-10-01

222

Improving pore filling of gel electrolyte and charge transport in photoanode for high-efficiency quasi-solid-state dye-sensitized solar cells.  

PubMed

We demonstrate the enhancement of pore-filling and wettability of gel electrolyte in quasi-solid-state dye-sensitized solar cells (DSSCs) by developing a kinetically driven electrolyte infiltration approach, in which the air purging provides the driving force. This method renders fast electrolyte diffusion throughout the three-dimensional TiO2 nanoparticle network, promising for large-area device fabrication. In addition, for the first time we incorporate multiwalled carbon nanotubes into the anode of quasi-solid-state DSSCs to improve the charge transfer efficiency and fill factor. These advancements finally generate an efficiency exceeding 7.0%, much higher than the device efficiency of 5.5% fabricated by the conventional method. PMID:23978250

Wang, Baohua; Chang, Shuai; Lee, Lawrence Tien Lin; Zheng, Shizhao; Wong, King Yong; Li, Quan; Xiao, Xudong; Chen, Tao

2013-08-29

223

Clustered charged-to-alanine mutagenesis of poliovirus RNA-dependent RNA polymerase yields multiple temperature-sensitive mutants defective in RNA synthesis.  

PubMed Central

To generate a collection of conditionally defective poliovirus mutants, clustered charged-to-alanine mutagenesis of the RNA-dependent RNA polymerase 3D was performed. Clusters of charged residues in the polymerase coding region were replaced with alanines by deoxyoligonucleotide-directed mutagenesis of a full-length poliovirus cDNA clone. Following transfection of 27 mutagenized cDNA clones, 10 (37%) gave rise to viruses with temperature-sensitive (ts) phenotypes. Three of the ts mutants displayed severe ts plaque reduction phenotypes, producing at least 10(3)-fold fewer plaques at 39.5 degrees C than at 32.5 degrees C; the other seven mutants displayed ts small-plaque phenotypes. Constant-temperature, single-cycle infections showed defects in virus yield or RNA accumulation at the nonpermissive temperature for eight stable ts mutants. In temperature shift experiments, seven of the ts mutants showed reduced accumulation of viral RNA at the nonpermissive temperature and showed no other ts defects. The mutations responsible for the phenotypes of most of these ts mutants lie in the N-terminal third of the 3D coding region, where no well-characterized mutations responsible for viable mutants had been previously identified. Clustered charged-to-alanine mutagenesis (S. H. Bass, M. G. Mulkerrin, and J. A. Wells, Proc. Natl. Acad. Sci. USA 88:4498-4502, 1991; W. F. Bennett, N. F. Paoni, B. A. Keyt, D. Botstein, J. J. S. Jones, L. Presta, F. M. Wurm, and M. J. Zoller, J. Biol. Chem. 266:5191-5201, 1991; and K. F. Wertman, D. G. Drubin, and D. Botstein, Genetics 132:337-350, 1992) is designed to target residues on the surfaces of folded proteins; thus, extragenic suppression analysis of such mutant viruses may be very useful in identifying components of the viral replication complex. Images

Diamond, S E; Kirkegaard, K

1994-01-01

224

Study of the sensitivity of neutron sensors consisting of a converter plus Si charged-particle detector  

NASA Astrophysics Data System (ADS)

With the aim of improving neutron sensors for monitoring external neutron exposure, we have analysed the workings of a converter plus silicon PIN diode detector arrangement. A phenomenological analysis of the conversion and signal generation of different converter materials and their effectiveness is given. The results are compared with experimental measurements. Because of the fundamentally different interactions of thermal neutrons versus high energy neutrons, we study the two species separately. For thermal neutrons, two types of neutron converters were examined, 6LiF (crystalline) and Kodak 10B films. For fast neutrons in the energy range from 1 to 20MeV hydrogen rich Lucite-PMMA (H8C5O2) and Polyethylene-PE (CH2) converters were studied. For thermal neutrons and a pure 10B-converter the theoretical response in counts/neutron reaches a value of BSTOT=0.0684 and for a pure 6LiF-converter LiFSTOT=0.0543. The corresponding experimental responses are 0.0062 for KODAK 10B film and 0.0223 for 6LiF converters. The difference between theory and experiment is understood by the necessity to use a lower level discriminator to eliminate unwanted counts coming from electrons and gammas. In the case of the 10B converter impurities in the converter material reduce the signal. Our analysis for fast neutrons allows us to calculate the ratio of sensitivity for Polyethylene to Lucite, for which we predict a value of 1.6. For the measured sensitivities for PE and PMMA, using an 241Am-Be neutron source, we obtain the values of 0.00225 and 0.0015 respectively, the ratio being 1.5.

Wielunski, M.; Schütz, R.; Fantuzzi, E.; Pagnamenta, A.; Wahl, W.; Palfálvi, J.; Zombori, P.; Andrasi, A.; Stadtmann, H.; Schmitzer, Ch.

2004-01-01

225

Linear Semiconductor Optical Amplifiers  

NASA Astrophysics Data System (ADS)

The chapter reviews properties and applications of linear semiconductor optical amplifiers (SOA). Section 12.1 covers SOA basics, including working principles, material systems, structures and their growth. Booster or inline amplifiers as well as low-noise preamplifiers are classified. Section 12.2 discusses the influence of parameters like gain, noise figure, gain saturation, gain and phase dynamics, and alpha-factor. In Sect. 12.3, the application of a linear SOA as a reach extender in future access networks is addressed. The input power dynamic range is introduced, and measurements for on-off keying and phase shift keying signals are shown. Section 12.4 presents the state of the art for commercially available SOA and includes a treatment of reflective SOAs (RSOA) as well.

Bonk, René; Vallaitis, Thomas; Freude, Wolfgang; Leuthold, Juerg; Penty, Richard; Borghesani, Anna; Lealman, Ian F.

226

PEAK LIMITING AMPLIFIER  

DOEpatents

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

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

1959-03-31

227

The Antares laser power amplifier  

Microsoft Academic Search

The overall design of the Antares laser power amplifier is discussed. The power amplifier is the last stage of amplification in the 100-kJ Antares laser. In the power amplifier a single, cylindrical, grid-controlled cold-cathode, electron gun is surrounded by 12 large-aperture CO2 electron-beam sustained laser discharge sectors. Each power amplifier will deliver 18 kJ and the six modules used in

R. D. Stine; G. F. Ross; C. Silvernail

1979-01-01

228

Plasma klystron amplifier  

NASA Astrophysics Data System (ADS)

A body of dense plasma is established within a short drift tube of a klystron amplifier between input and output resonator cavities thereof to support current modulation of microwave energy by interaction with an electron beam propagated through the drift tube. The plasma is confined to a column radially spaced from the electron beam for two-stream interaction enabling enhancement of current modulation under simultaneous high-power and high frequency operation.

Uhm, Han S.

1993-05-01

229

Plasma klystron amplifier  

NASA Astrophysics Data System (ADS)

A body of dense plasma is established within a short drift tube of a klystron amplifier between input and output resonator cavities thereof to support current modulation of microwave energy by interaction with an electron beam propagated through the drift tube. The plasma is confined to a column radially spaced from the electron beam for two-stream interaction enabling enhancement of current modulation under simultaneous high-power and high frequency operation.

Uhm, Han S.

1995-01-01

230

Helical Fiber Amplifier  

DOEpatents

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

Koplow, Jeffrey P. (Washington, DC); Kliner, Dahy (San Ramon, CA); Goldberg, Lew (Fairfax, VA)

2002-12-17

231

Monolithic low noise amplifiers  

NASA Astrophysics Data System (ADS)

A GaAs monolithic low-noise X-band amplifier has been developed which demonstrates a noise figure of 2.8 dB with an associated gain of 8.5 dB at 12 GHz. The circuits were formed using direction implantation into semiinsulating GaAs, which is the technology of choice for low cost, high volume applications. Monolithic fabrication is described, and RF results are presented.

Maki, D. W.; Esfandiari, R.; Siracusa, M.

1981-10-01

232

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

SciTech Connect

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.

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

1997-02-01

233

Gas amplified ionization detector for gas chromatography  

DOEpatents

A gas-amplified ionization detector for gas chromatography which possesses increased sensitivity and a very fast response time is described. Solutes eluding from a gas chromatographic column are ionized by uv photoionization of matter eluting therefrom. The detector is capable of generating easily measured voltage signals by gas amplification/multiplication of electron products resulting from the uv photoionization of at least a portion of each solute passing through the detector. 4 figs.

Huston, G.C.

1989-11-27

234

Gas amplified ionization detector for gas chromatography  

DOEpatents

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

Huston, Gregg C. (LaBelle, PA)

1992-01-01

235

Dust detector using piezoelectric lead zirconate titanate with current-to-voltage converting amplifier for functional advancement  

NASA Astrophysics Data System (ADS)

This paper describes the concept of a dust monitor using lead zirconate titanate (PZT) ceramics with a large detection area. Its potential as a dust detector is experimentally demonstrated. The dust monitor has a small volume compared to an impact ionization detector with the same detection area, due to the PZT sensor. The PZT sensor, as a traditional device for the in-situ observation of hypervelocity dust particles, has been used for momentum measurement. The hypervelocity impact signals of PZT sensors are typically read by charge-sensitive amplifiers. Instead, we suggest a new method that a current-to-voltage converting amplifier is useful for interpreting the impact signal of a PZT sensor arising from dust particles down to 0.5 ?m in radius. We propose that datasets of dust impacts can be obtained with a higher statistical accuracy, if the new method is applied to instruments on forthcoming interplanetary-space-cruising spacecrafts.

Kobayashi, M.; Miyachi, T.; Hattori, M.; Sugita, S.; Takechi, S.; Okada, N.

2013-03-01

236

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

DOEpatents

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.

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

1993-01-01

237

Ways to suppress click and pop for class D amplifiers  

NASA Astrophysics Data System (ADS)

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

Haishi, Wang; Bo, Zhang; Jiang, Sun

2012-08-01

238

Invited Review Article: The Josephson bifurcation amplifier  

NASA Astrophysics Data System (ADS)

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 I0 and results in a dispersive shift in the resonator plasma frequency ?p. This shift is enhanced by biasing the junction with a sufficiently strong microwave current Irf to access the nonlinear regime where ?p varies with Irf. For a drive frequency ?d such that ?=2Q(1-?d/?p)>3, the oscillator enters the bistable regime where two nondissipative dynamical states OL and OH, which differ in amplitude and phase, can exist. The sharp I0 dependent transition from OL to OH forms the basis for a sensitive digital threshold amplifier. In the vicinity of the bistable regime (?<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).

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

2009-11-01

239

Nanoclay gelation approach toward improved dye-sensitized solar cell efficiencies: an investigation of charge transport and shift in the TiO2 conduction band.  

PubMed

Nanoclay minerals play a promising role as additives in the liquid electrolyte to form a gel electrolyte for quasi-solid-state dye-sensitized solar cells, because of the high chemical stability, unique swelling capability, ion exchange capacity, and rheological properties of nanoclays. Here, we report the improved performance of a quasi-solid-state gel electrolyte that is made from a liquid electrolyte and synthetic nitrate-hydrotalcite nanoclay. Charge transport mechanisms in the gel electrolyte and nanoclay interactions with TiO(2)/electrolyte interface are discussed in detail. The electrochemical analysis reveals that the charge transport is solely based on physical diffusion at the ratio of [PMII]:[I(2)] = 10:1 (where PMII is 1-propyl-3-methylimidazolium iodide). The calculated physical diffusion coefficient shows that the diffusion of redox ions is not affected much by the viscosity of nanoclay gel. The addition of nitrate-hydrotalcite clay in the electrolyte has the effect of buffering the protonation process at the TiO(2)/electrolyte interface, resulting in an upward shift in the conduction band and a boost in open-circuit voltage (V(OC)). Higher V(OC) values with undiminished photocurrent is achieved with nitrate-hydrotalcite nanoclay gel electrolyte for organic as well as for inorganic dye (D35 and N719) systems. The efficiency for hydrotalcite clay gel electrolyte solar cells is increased by 10%, compared to that of the liquid electrolyte. The power conversion efficiency can reach 10.1% under 0.25 sun and 9.6% under full sun. This study demonstrates that nitrate-hydrotalcite nanoclay in the electrolyte not only solidifies the liquid electrolyte to prevent solvent leakage, but also facilitates the improvement in cell efficiency. PMID:23252392

Wang, Xiu; Kulkarni, Sneha A; Ito, Bruno Ieiri; Batabyal, Sudip K; Nonomura, Kazuteru; Wong, Chee Cheong; Grätzel, Michael; Mhaisalkar, Subodh G; Uchida, Satoshi

2012-12-31

240

A magnetic amplifier for amplifying spin-wave signal  

Microsoft Academic Search

In summary, a microstrip-line type spin-wave amplifier was demonstrated with a power gain controlled by the pump power level. Our prototype amplifier achieved a power gain of 8.7 dB at 1.3 GHz with the pump power of 14.9 dBm (31 mW). With the use of this amplifier, spin wave based devices can be cascaded in a large area network such

Mingqiang Bao; A. Khitun; JooYoung Lee; A. P. Jacob; K. L. Wang

2009-01-01

241

DIAMOND AMPLIFIED PHOTOCATHODES.  

SciTech Connect

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

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

2007-11-26

242

SQUID linear amplifier circuit simulations  

SciTech Connect

This paper presents numerical simulations of a single stage of a linear SQUID amplifier. The amplifier stage is fabricated in thin film technology, and consists of two asymmetric SQUIDs placed in the push-pull configuration. It was found that the Q of the tank circuit formed by SQUID inductance and a parasitic strip-line capacitance must be reduced to unity to avoid hysteretic operation. A load line analysis has determined the amplifier operating point and SQUID inductance which yield optimum linearity.

Gershenson, M.; Hastings, R.; Schneider, R.; Sorensen, E.; Sweeny, M.

1983-09-01

243

Composite instrumentation amplifier for biopotentials  

Microsoft Academic Search

We present the design of an instrumentation biopotential amplifier that, (a) combines the ac coupling and high input impedance\\u000a of an ac-coupled buffer with the CMRR of a simple differential amplifier or a monolithic instrumentation amplifier, (b) improves\\u000a the CMRR by using a potentiometer without requiring either precision resistors or high-CMRR op amps, (c) illustrates how to\\u000a calculate the CMRR

R. Pallfis-Areny; J. G. Webster

1990-01-01

244

Fiber-amplifier-enhanced photoacoustic spectroscopy with near-infrared tunable diode lasers  

Microsoft Academic Search

A new approach to wavelength-modulation photoacoustic spectroscopy is reported, which incorporates diode lasers in the near infrared and optical fiber amplifiers to enhance sensitivity. We demonstrate the technique with ammonia detection, yielding a sensitivity limit less than 6 parts in 109, by interrogating a transition near 1532 nm with 500 mW of output power from the fiber amplifier, an optical

Michael E. Webber; Michael Pushkarsky; C. Kumar N. Patel

2003-01-01

245

Fiber-Amplifier-Enhanced Photoacoustic Spectroscopy with Near-Infrared Tunable Diode Lasers  

Microsoft Academic Search

A new approach to wavelength-modulation photoacoustic spectroscopy is reported, which incorporates diode lasers in the near infrared and optical fiber amplifiers to enhance sensitivity. We demonstrate the technique with ammonia detection, yielding a sensitivity limit less than 6 parts in 109, by interrogating a transition near 1532 nm with 500 mW of output power from the fiber amplifier, an optical

Michael E. Webber; Michael Pushkarsky; C. Kumar

2003-01-01

246

Wavelength tunable alexandrite regenerative amplifier  

SciTech Connect

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

Harter, D.J.; Bado, P.

1988-11-01

247

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

PubMed

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

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

2012-10-03

248

Ru-based donor-acceptor photosensitizer that retards charge recombination in a p-type dye-sensitized solar cell.  

PubMed

We report on the synthesis and characterization of a donor-acceptor ruthenium polypyridyl complex as a photosensitizer for p-type dye-sensitized solar cells (DSSCs). The electrochemical, photophysical, and photovoltaic performance of two ruthenium-based photosensitizers were tested in NiO-based DSSCs; bis-(2,2'-bipyridine-4,4'-dicarboxylic acid)(2)N-(1,10-phenanthroline)-4-nitronaphthalene-1,8-dicarboximide ruthenium(II), ([Ru(dcb)(2)(NMI-phen)](PF(6))(2)) and tris-(2,2'-bipyridine-4,4'-dicarboxylic acid)(3) ruthenium(ii), [(Ru(dcb)(3))Cl(2)]. The presence of an electron-accepting group, 4-nitronaphthalene-1,8-dicarboximide (NMI), attached to the phenanthroline of [Ru(dcb)(2)(NMI-phen)](2+) resulted in long-lived charge separation between reduced [Ru(dcb)(2)(NMI-phen)](2+) and NiO valence band holes; 10-50 ?s. In the reduced state for [Ru(dcb)(2)(NMI-phen)](2+), the electron localized on the distal NMI group. In tests with I(3)(-)/I(-) and Co(4,4'-di-tert-butyl-bipyridine)(3)(2+/3+) electrolytes, [Ru(dcb)(2)(NMI-phen)](2+) outperformed [Ru(dcb)(3)](2+) in solar cell efficiency in devices. A record APCE (25%) was achieved for a ruthenium photosensitizer in a p-type DSSC. Insights on photosensitizer regeneration kinetics are included. PMID:23018189

Freys, Jonathan C; Gardner, James M; D'Amario, Luca; Brown, Allison M; Hammarström, Leif

2012-11-14

249

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

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

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

250

Ultrathin SnO2 scaffolds for TiO2-based heterojunction photoanodes in dye-sensitized solar cells: oriented charge transport and improved light scattering.  

PubMed

In this paper, band-structure matching strategy of a TiO2-based heterojunction within which electrons can be collected from TiO2 nanoparticles and transported rapidly in the bulk structure is reported. On the basis of the band-structure analysis of different TiO2-based heterostructures, focus was directed to the SnO2 nanosheet because of its appropriate band position and high electrical conductivity. Through a systematic investigation of the incorporation of ultrathin SnO2 nanosheet scaffolds for TiO2-based photoanodes in dye-sensitized solar cells (DSCs), we propose an anisotropy "constrained random walk" model to describe the controlled electron transit process. In this system, electrons are transferred orientedly overall, as well as randomly locally, leading to a significant reduction in the charge diffusion route compared to the conventional isotropic "random walk" model. In brief, the 2D ultrathin nanosheets provide rapid transit pathways and improved light-scattering centers, which can ensure a sufficient amount of dye loading and slow recombination. An overall light-to-electricity conversion efficiency as high as 8.25% is achieved by embedding the appropriate amount of SnO2 scaffold in a TiO2-based photoanode. PMID:23733334

Yang, Shuang; Hou, Yu; Xing, Jun; Zhang, Bo; Tian, Feng; Yang, Xiao Hua; Yang, Hua Gui

2013-06-03

251

Optical Parametric Generators and Amplifiers  

Microsoft Academic Search

Mid-infrared parametric generators and amplifiers in quasi-phase-matched and birefirngence phase-matched nonlinear crystals\\u000a are reviewed. Broadband mid-infrared generation using collinear and noncollinear parametric interactions is discussed.\\u000a \\u000a Keywords: Mid-infrared sources; optical parametric generators and amplifiers; quasi-phasematching.

Valdas Pasiskevicius; Fredrik Laurell

252

Amplifier for Fiber Optics Application.  

National Technical Information Service (NTIS)

The patent application relates to an amplifier for use with a photodiode in an electro-optical transmission line. A transimpedance amplifier is connected to an output port of a photodiode and a T-network feedback circuit is provided as a feedback element ...

R. A. Morrison

1976-01-01

253

Laser amplifier developments at Mercury  

Microsoft Academic Search

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.

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

1993-01-01

254

Antares power amplifier optical system  

Microsoft Academic Search

The optical systems of the six Antares laser power amplifiers are described. These assemblies are preceded by the front end optics and followed by the target system. Each power amplifier receives an annular input beam and divides it into 12 beams which are then directed to double pass them through 12 gain regions surrounding a central electron gun. Provisions are

C. J. Silvernail; K. C. Jones

1979-01-01

255

X-band paraphase amplifier  

NASA Astrophysics Data System (ADS)

A design method for paraphase amplifiers is described. The feasibility of balun action with gain is demonstrated by means of a paraphase amplifier over the range 9-11 GHz with a gain difference between the two ways of less than 0.9 dB and deviation from antiphase of less than 3 deg.

Levent-Villegas, M.

1984-05-01

256

Charging apparatus  

SciTech Connect

A diode is disposed in the vicinity of a rechargeable battery. A current is applied to the diode from a current generating circuit. The current generating circuit comprises a thermistor which is responsive to the ambient temperature, so that a current associated with the ambient temperature is applied from the current generating circuit to the diode. The diode gives rise to a forward voltage drop, which is changeable as a function of the battery temperature. Accordingly, the forward voltage drop across the diode is changeable as a function of the ambient temperature and the battery temperature. The forward voltage drop across the diode is amplified to be used as a reference voltage. On the other hand, the rechargeable battery is supplied with a charging current from a power supply through a thyristor. The gate electrode of the thyristor is connected to receive the reference voltage and the cathode of the thyristor is connected to the battery. Accordingly, the thyristor is turned off if and when the difference between the reference voltage and the battery voltage becomes smaller than the switching voltage of the thyristor.

Furukawa, K.; Kakumoto, H.

1983-01-25

257

A wideband dc-coupled amplifier  

Microsoft Academic Search

A method is described whereby an ac-coupled high-frequency amplifier and a dc-coupled low-frequency amplifier are connected in parallel in order to obtain a dc-coupled wideband amplifier. By using an operational amplifier which compares the output voltage with the input voltage, the low-frequency amplifier contributes to the overall gain only when the gain of the ac-coupled amplifier droops at low frequencies.

E. Janata

2003-01-01

258

A high-speed low-noise CMOS 16-channel charge-sensitive preamplifier ASIC for APD-based PET detectors  

Microsoft Academic Search

A high-speed low-noise 16-channel amplifier integrated circuit (IC) has been fabricated in a 0.5 ?m CMOS process. It is a prototype for use with a PET detector that uses a 4×4 avalanche photodiode (APD) array having 3 pF of capacitance and 75 nA of leakage current per pixel. The preamplifier must have a fast rise time (a few ns) in

M. Weng; E. Mandelli; W. W. Moses; S. E. Derenzo

2003-01-01

259

A high-speed, low-noise CMOS 16-channel charge-sensitive preamplifier ASIC for APD-based PET detectors  

Microsoft Academic Search

A high-speed, low-noise 16-channel amplifier IC has been fabricated in the UP 0.5 ?m CMOS process. It is a prototype for use with a PET detector which uses a 4×4 avalanche photodiode (APD) array having 3 pF of capacitance and 75 nA of leakage current. This requires that the preamplifier have a fast rise time (a few ns) in order

M. Weng; E. Mandelli; W. W. Moses; S. E. Derenzo

2002-01-01

260

A single supply biopotential amplifier.  

PubMed

A biopotential amplifier for single supply operation is presented. It uses a Driven Right Leg Circuit (DRL) to drive the patient's body to a DC common mode voltage, centering biopotential signals with respect to the amplifier's input voltage range. This scheme ensures proper range operation when a single power supply is used. The circuit described is especially suited for low consumption, battery-powered applications, requiring a single battery and avoiding switching voltage inverters to achieve dual supplies. The generic circuit is described and, as an example, a biopotential amplifier with a gain of 60 dB and a DC input range of +/-200 mV was implemented using low power operational amplifiers. A Common Mode Rejection Ratio (CMRR) of 126 dB at 50 Hz was achieved without trimming. PMID:11410389

Spinelli, E M; Martinez, N H; Mayosky, M A

2001-04-01

261

A Broadband Complementary Transistor Amplifier.  

National Technical Information Service (NTIS)

A two-stage NPN-PNP complementary transistor amplifier with great versatility over a broad frequency range is described herein. This circuit configuration provides high-input impedance and low-output impedance coupled with extremely stable gain characteri...

R. S. Hughes R. A. Mammano

1965-01-01

262

A Dual Stage GaAs Amplifier for a K-Band Direct Receiver  

Microsoft Academic Search

An energy efficient K-band GaAs-HBT amplifier applicable in a highly integrated direct receiver concept for sensor networks is presented. The preamplifier in a direct receiver is the most important building block and mainly determines sensitivity and energy consumption. Special issues of the amplifier design related to the receiver concept are highlighted in this paper. The presented amplifier shows gain of

Meik Huber; Stefan von der Mark; Georg Boeck

2006-01-01

263

FM microwave multiplexed broad-band distribution systems using Er sup 3 + fiber amplifiers and preamplifiers  

SciTech Connect

The first use of an Er{sup 3 +} fiber preamplifier for microwave multiplexed systems, and the use of an in-line Er{sup 3 +} amplifier in microwave multiplexed systems for signal distribution, is reported. The improvement in receiver sensitivity as a preamplifier, without optical filtering, was 9 dB. No power penalty due to amplified spontaneous emission is found when the amplifier is used in a 30 channel signal distribution system.

Eichen, E.; McCabe, J.; Miniscalco, W.J.; Olshansky, R.; Wei, T. (GTE Labs., Inc., Waltham, MA (USA))

1990-03-01

264

Use of charge sensitivity analysis in diagnosing chemisorption clusters: Minimum-energy coordinate and Fukui function study of model toluene-[V{sub 2}O{sub 5}] systems  

SciTech Connect

Charge sensitivity analysis (CSA) is carried out for model toluene-vanadium pentoxide chemisorption complexes involving the two-pyramidal model of the active site on the (010)-V{sub 2}O{sub 5} surface. Maps of the electrostatic potential around the adsorbate and the substrate cluster are used to rationalize energetical preferences of alternative perpendicular and parallel arrangements of the toluene ring relative to the pyramid bases, known from previous SCF MO studies. The minimum-energy coordinates (MEC) in the electron population space are determined from the CSA semiempirical, finite difference atomic hardness matrix for the actual SCF MO charges in the chemisorption clusters. They represent collective charge displacements which minimize the system energy per unit change in the oxidation state of a specified atom, thus providing a convenient diagnostic tool for testing the alternative charge rearrangements and range of perturbations due to the chemisorption bond or changes in the cluster environment. The MEC relaxed hardnesses diagnose mode stabilities and together with the MEC relaxed hardnesses diagnose mode stabilities and together with the MEC topologies identify the most probable locations of the adsorbate activation. Finally, the atomic Fukui function indices are used to explore trends in the distribution of the external charge transfer due to the system environment. 14 refs., 4 figs.

Nalewajski, R.F.; Michalak, A. [Jagiellonian Univ., Cracow (Poland)

1995-12-05

265

A 2pA\\/?Hz 622 Mb\\/s GaAs MESFET transimpedance amplifier  

Microsoft Academic Search

Telecommunication systems require high sensitivity transimpedance amplifiers with wide dynamic range for loopback testing. Although GaAs MESFET technology has superior noise performance compared to silicon technology for transimpedance amplifiers, this has not been fully exploited. Low voltage gain, which leads to a small feedback resistor, and the use of numerous active devices that have significant channel noise degrades the noise

S. S. Taylor; T. P. Thomas

1994-01-01

266

The Free Electron Laser Klystron Amplifier Concept  

Microsoft Academic Search

The simplest high gain free electron laser (FEL) amplifier concept is proposed. A klystron amplifier has the useful property that the various electronic processes take place in separate portions of the amplifier, rather than overlapping as in FEL amplifier with an uniform undulator. The klystron consists of two fundamental parts: succession of 2-3 cascades (modulator), and an output undulator (radiator)

E. L. Saldin; E. A. Schneidmiller; M. V. Yurkov

2003-01-01

267

High-voltage switching piezo drive amplifier  

Microsoft Academic Search

This paper describes the development and testing of a 4KVpp, 750 ma piezo drive switching amplifier. This amplifier is used to drive Piezo Fiber Composite material imbedded in a 1\\/6 scale CH-47 blade. This amplifier will allow higher harmonic control of the blade thus reducing rotor craft vibration and nose. The amplifier recycles reactive energy required to drive piezo material

Dan J. Clingman; Mike Gamble

1999-01-01

268

High-voltage switching piezo drive amplifier  

Microsoft Academic Search

This paper describes the development and testing of a 3KV, 400 ma piezo drive switching amplifier. This amplifier is used to drive Piezo Fiber Composite material embedded in a 1\\/6 scale CH-47 blade. This amplifier will allow higher harmonic control of the blade thus reducing rotor craft vibration and noise. The amplifier recycles reactive energy required to drive piezo material

Dan J. Clingman; Mike Gamble

1998-01-01

269

Fully differential cryogenic transistor amplifier  

NASA Astrophysics Data System (ADS)

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.

Beev, Nikolai; Kiviranta, Mikko

2013-10-01

270

Reflex ring laser amplifier system  

DOEpatents

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.

Summers, M.A.

1983-08-31

271

A high-power millimeter-wave sheet beam free-electron laser amplifier  

SciTech Connect

The results of experiments with a short period (9.6 mm) wiggler sheet electron beam (1.0 mm x 2.0 cm) millimeter-wave free electron laser (FEL) amplifier are presented. This FEL amplifier utilized a strong wiggler field for sheet beam confinement in the narrow beam dimension and an offset-pole side-focusing technique for the wide dimension beam confinement. The beam analysis herein includes finite emittance and space-charge effects. High-current beam propagation was achieved as a result of extensive analytical studies and experimental optimization. A design optimization resulted in a low sensitivity to structure errors and beam velocity spread, as well as a low required beam energy. A maximum gain of 24 dB was achieved with a 1-kW injected signal power at 86 GHz, a 450-kV beam voltage, 17-A beam current, 3.8-kG wiggler magnetic field, and a 74-period wiggler length. The maximum gain with a one-watt injected millimeter-wave power was observed to be over 30 dB. The lower gain at higher injection power level indicates that the device has approached saturation. The device was studied over a broad range of experimental parameters. The experimental results have a good agreement with expectations from a one-dimensional simulation code. The successful operation of this device has proven the feasibility of the original concept and demonstrated the advantages of the sheet beam FEL amplifier. The results of the studies will provide guidelines for the future development of sheet beam FEL`s and/or other kinds of sheet beam devices. These devices have fusion application.

Cheng, S.; Destler, W.W.; Granatstein, V.L.; Antonsen, T.M.; Levush, B.; Rodgers, J.; Zhang, Z.X. [Univ. of Maryland, College Park, MD (United States)

1996-06-01

272

Radiating Charge  

NSDL National Science Digital Library

The electric field lines from a point charge evolve in time as the charge moves. Watch radiation propagate outward at the speed of light as you wiggle the charge. Stop a moving charge to see bremsstrahlung (braking) radiation. Explore the radiation patterns as the charge moves with sinusoidal, circular, or linear motion. You can move the charge any way you like, as long as you donât exceed the speed of light.

Simulations, Phet I.; Dubson, Michael; Paul, Ariel

2013-02-01

273

Amplifying mirrors for terahertz plasmons  

NASA Astrophysics Data System (ADS)

Semiconductor plasmons have long held out a promise for terahertz generation, but competitive plasmonic mechanisms have yet to be found. Here, we introduce amplifying terahertz mirrors: planar interfaces for two-dimensional electron channels that amplify plasmons in the presence of electron drift. In contrast to existing formulations, we develop a rigorous mode matching technique that takes the complete mode spectrum into account. Mirrors are characterized by plasmon reflection and transmission coefficients whose values can increase with drift. Amplitude and power coefficients are determined, and conditions are found for their values to exceed unity. Resonators based on different combinations of amplifying mirrors are investigated, and an asymmetric configuration (consisting of two different electron channels confined between conducting planes) whose roundtrip gain can exceed unity is identified. The unusual conditions needed for oscillation are examined in detail and the general advantages of asymmetric arrangements are highlighted. Finally, the potential of mode matching as a universal tool for plasmonics is discussed.

Sydoruk, O.; Syms, R. R. A.; Solymar, L.

2012-11-01

274

Sagnac interferometric multipass loop amplifier.  

PubMed

We propose and investigate experimentally an interferometrically stable, polarization-selective pulse multiplexing scheme for direct laser amplification of picosecond pulses. The basic building block of this scheme is a Sagnac loop which allows for a straightforward scaling of the pulse-multiplexing scheme. Switching the amplifier from single-pulse amplification to burst mode increases extraction efficiency, reduces parasitic non-linearities in the gain medium and allows for higher output energies. Time-frequency analysis of the amplified output pulses demonstrates the viability of this approach. PMID:23187278

Roither, S; Verhoef, A J; Mücke, O D; Reider, G A; Pugžlys, A; Baltuška, A

2012-10-22

275

Laser system using regenerative amplifier  

DOEpatents

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

Emmett, John L. (Pleasanton, CA)

1980-01-01

276

Laser system using regenerative amplifier  

DOEpatents

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

Emmett, J.L.

1980-03-04

277

A very sensitive ion collection device for plasma-laser characterization.  

PubMed

In this paper a very sensitive ion collection device, for diagnostic of laser ablated-target plasma, is described. It allows for reducing down to few microvolts the signal threshold at digital scope input. A standard ion collector is coupled to a transimpedance amplifier, specially designed, which increases data acquisition sensitivity by a gain ?1100 and does not introduce any significant distortion of input signal. By time integration of current intensity, an amount of charge as small as 2.7 × 10(-2) pC can be detected for photopeak events. PMID:22755620

Cavallaro, S; Torrisi, L; Cutroneo, M; Amato, A; Sarta, F; Wen, L

2012-06-01

278

A very sensitive ion collection device for plasma-laser characterization  

NASA Astrophysics Data System (ADS)

In this paper a very sensitive ion collection device, for diagnostic of laser ablated-target plasma, is described. It allows for reducing down to few microvolts the signal threshold at digital scope input. A standard ion collector is coupled to a transimpedance amplifier, specially designed, which increases data acquisition sensitivity by a gain ~1100 and does not introduce any significant distortion of input signal. By time integration of current intensity, an amount of charge as small as 2.7 × 10-2 pC can be detected for photopeak events.

Cavallaro, S.; Torrisi, L.; Cutroneo, M.; Amato, A.; Sarta, F.; Wen, L.

2012-06-01

279

Amplified quenching of electrochemiluminescence from CdS sensitized TiO2 nanotubes by CdTe-carbon nanotube composite for detection of prostate protein antigen in serum.  

PubMed

This work reports an ECL immunoassay method for ultrasensitive detection of prostate protein antigen (PSA), by remarkably efficient energy-transfer induced electrochemiluminescence (ECL) quenching from the CdS nanoparticles (NPs) sensitized TiO(2) nanotube array (CdS-TiO(2) NTs) to the activated CdTe NPs functionalized multi-wall carbon nanotubes (CdTe-MWNTs) composite. The coupling of TiO(2) and CdS NPs results in a cathodic ECL intensity 14.7 times stronger than that of the pure TiO(2) NTs electrode, which could be efficiently quenched by the CdTe-MWNTs. The enhanced mechanism of TiO(2) NTs ECL by CdS NPs was studied in detail by cyclic voltammetry and ECL spectroscopy. The strong absorption of the CdTe-MWNTs in the wavelength range of 400-800 nm renders them highly efficient for ECL quenching labeled on anti-PSA antibody. Based on a sandwich structure, we developed an ECL immunoassay method for the sensitive and selective detection of PSA. The ECL intensity decrement was logarithmically related to the concentration of the PSA in the range of 1.0 fg mL(-1) to 10 pg mL(-1) with a detection limit of 1 fg mL(-1). Human serum samples were then tested using the proposed immunoassay with excellent correlations, suggesting that the proposed immunoassay method is of great promise in clinical screening of cancer biomarkers. PMID:22624149

Tian, Chun-Yuan; Zhao, Wei-Wei; Wang, Jing; Xu, Jing-Juan; Chen, Hong-Yuan

2012-05-23

280

Comparative Studies on the Interfacial Behaviour of Adenylyl(3?—5?)Guanosine by Phase Sensitive AC Voltamhetry, Pulse Voltammetry and Single Sweep Voltahhetry at Charged Interfaces  

Microsoft Academic Search

Adeny ly 1-.(3?—5?)-guanosine has been investigated in order to expand the potentialities of pulse voltammetry and phase sensitive ac voltammetry in connection with the HMDE for study of the adsorption and interfacial behaviour of the investigated compound. The results are compared with rapid single sweep voltammetry being sensitive to the faradaic reduction response of the adsorbed substance. From the limiting

M. M. Kamal; Z. A. Ahmed; M. E. Ahmed; M. S. Ibrahim; Y. M. Temerk

1992-01-01

281

The PreAmplifier ShAper for the ALICE TPC detector  

NASA Astrophysics Data System (ADS)

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.

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

282

A wideband dc-coupled amplifier  

NASA Astrophysics Data System (ADS)

A method is described whereby an ac-coupled high-frequency amplifier and a dc-coupled low-frequency amplifier are connected in parallel in order to obtain a dc-coupled wideband amplifier. By using an operational amplifier which compares the output voltage with the input voltage, the low-frequency amplifier contributes to the overall gain only when the gain of the ac-coupled amplifier droops at low frequencies. Thus, no frequency splitting networks are necessary and the excellent low-frequency features of an operational amplifier are added to those of the ac-coupled wideband amplifier. As an example, a low noise amplifier is described which exhibits a hundredfold gain, a bandwidth from dc to 550MHz, an input bias current of less than 1nA, and an output voltage range of +/-1V.

Janata, E.

2003-03-01

283

Amplified Fiber-Loop Ringdown Spectroscopy  

NASA Astrophysics Data System (ADS)

Many commercial liquid chemical analysis systems, such as high-performance liquid chromatography (HPLC) or capillary electrophoresis consist of a separation followed by optical detection. Besides small volumes and low detection limits, the system should also allow the detection of a large variety of analytes. Existing absorption and fluorescence detectors are often not very sensitive or require labelling. Here, an absorption detector is presented based on cavity ring-down spectroscopy (CRDS) where the optical cavity is made from fibre optic waveguides and the light source is a continuous wave (cw) diode laser. The purpose of this project is to increase the detection of analytes through their overtone absorption in the telecom region at 1300 to 1500 nm. This is done by increasing the ratio of desired loss (extinction caused by the sample), to undesirable loss (due to the waveguides or solvents) through amplification of the ringdown signal using a gain-clamped erbium doped fibre amplifier (EDFA). The amplified cavity has a round-trip time of 750 ns and we achieved a detection limit of at most 250 ppm when measuring acetylene at 1532.83 nm. The application of our method to detection of dissolved analytes or particles in liquids will be discussed.

Litman, Jessica; Barnes, Jack; Loock, Hans-Peter

2009-06-01

284

Two pieces for amplified guitar  

Microsoft Academic Search

This article addresses the aesthetic, theoretic, idiomatic, and technical problems encountered by the author while programming a computer to compose his Excursion and Artifacts for solo amplified guitar. Heading 1, “Background”, places these pieces in the greater context of the author's work and outlines his methodology. Heading 2, “Tonality”, describes a circular arrangement of the twelve chromatic degrees; positions closest

Charles Ames

1986-01-01

285

Avalanche Diode Sources and Amplifiers.  

National Technical Information Service (NTIS)

The significance of this research and development to the Air Force is the extension of the operational range of high-efficiency silicon avalanche diodes from the original L-band into the S-, C-, X-, and Ku-bands and from the oscillator mode to the amplifi...

K. K. N. Chang A. S. Clorfeine R. V. D'Aiello R. J. Ikola H. Kawamoto

1971-01-01

286

Plastic molded analog isolation amplifier  

Microsoft Academic Search

A plastic-packaged analog isolation amplifier that utilizes a capacitive coupled path for encoded signals and is capable of operating at high voltage levels is described. The assembly uses standard techniques for building plastic packages, allowing high-volume assembly at low cost without sacrificing performance. There is a small interconnect circuit which is used to capacitively couple the signal from the input

W. Meinel

1990-01-01

287

Linearisation Issues in Microwave Amplifiers  

Microsoft Academic Search

The European Union has established the TARGET network of excellence (NoE) to focus on microwave power amplifier (PA) technology research. It aims to integrate the research resources comprised of many research groups covering the full range of expertise in PA technology. TARGET'S linearisation expertise covers leading edge researchers in classical and new linearisation techniques, including feedforward, predistortion, feedback and envelope

M. S. O'Droma; J. Portilla; E. Bertran; S. Donati; T. J. Brazil; M. Rupp; R. Quay

288

Design Theory for Laser Amplifiers.  

National Technical Information Service (NTIS)

A theoretical and experimental study was carried out on laser amplification. A transmission system was set up with an oscillator, filter, amplifier, and detector. By controlling the relative time delays in firing or by changing the power input to the ampl...

H. Jacobs F. A. Brand S. Weitz C. Lo Cascio

1964-01-01

289

Stroke amplifier for deformable mirrors  

PubMed Central

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

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

2010-01-01

290

L Band Linear Power Amplifier.  

National Technical Information Service (NTIS)

The development of a linear power amplifier at L band suitable for application to a satellite phased array antenna is described. The main effort was devoted to the definition of the linearization technique and to its optimization. The result of the study ...

S. Padovani P. L. Faja

1974-01-01

291

Amplifier Principles - Coupling, Pt 1.  

National Technical Information Service (NTIS)

Explains the direct coupling of amplifier stages. Gives the limitations and the main advantage of direct coupling. Discusses rc coupling, showing the schematic and explaining the purpose of the components. Traces the path of an ac signal through the rc co...

1994-01-01

292

Composite instrumentation amplifier for biopotentials.  

PubMed

We present the design of an instrumentation biopotential amplifier that, (a) combines the ac coupling and high input impedance of an ac-coupled buffer with the CMRR of a simple differential amplifier or a monolithic instrumentation amplifier, (b) improves the CMRR by using a potentiometer without requiring either precision resistors or high-CMRR op amps, (c) illustrates how to calculate the CMRR for differential-input stages for either differential output or single-ended output. With our approach, for the 741 op amp, the CMRR of the differential stage exceeds 126 dB at 10 Hz and 106 dB at 100 Hz, which is higher than the 90 dB of the op amp alone. This is because a potentiometer permits mismatch of the resistor ratio, which compensates for the low CMRR of the op amp. Use of the LF355 op amp, which has a wider band-width, yields a CMRR of 126 dB at both 10 and 100 Hz. If the second stage is an instrumentation amplifier then no adjustment is necessary. Mismatch of passive components in the bootstrapped input buffer stage decreases the CMRR from 126 dB to 112 dB at 60 Hz and decreases it further at lower frequencies, but that is not a problem for the usual power-line interference. PMID:2372162

Pallás-Areny, R; Webster, J G

1990-01-01

293

Final amplifier for laser accelerators  

NASA Astrophysics Data System (ADS)

We demonstrate the existence of the severe losses due ASE and ability EDP technique to suppress it andparasitic lasing. The optimal conditions that can deliver up to kJ level energy with existing technology are presented. Keywords: Ultrahigh power lasers; Laser amplifiers.

Yanovsky, V. Chvykov V.; Kalinchenko, G.; Rousseau, P.; Maksimchuk, A.; Krushelnick, K.

2012-12-01

294

A Low Noise Low Power DC Coupled Sensor Amplifier with Offset Cancellation  

Microsoft Academic Search

A 16-channel sensor amplifier was designed in the Jazz 0.18 ¿m CMOS process. The sensor amplifier has programmable gain from 20 to 2000 and a DC offset cancellation of ±0.3 V using bulk voltage control. A charge pump, band gap reference and a resistor string DAC were designed for bulk voltage control. Input referred noise of 0.465 ¿V was achieved

Hari Krishnan Krishnamurthy; Dirk Robinson; Dave M. Rector; George S. La Rue

2010-01-01

295

Planar position sensitive Ge(i)- and Si(Li)-detector systems for Compton Polarimetry in Atomic Physics with Highly Charged Ions  

NASA Astrophysics Data System (ADS)

Planar position-, energy-, and time-dispersive semiconductor detector systems have shown their excellent performance in Compton Polarimetry and X-ray Imaging in the realm of Atomic Physics Experiments with Highly Charged Ions. We report on two of these detector systems and discuss the importance of this kind of detector systems for the present and future experimental programm of the SPARC collaboration at GSI and FAIR.

Spillmann, U.; Blumenhagen, K.-H.; Bräuning, H.; Weber, G.; Stöhlker, Th

2012-11-01

296

Development of a low-noise, two-dimensional amplifier array  

NASA Astrophysics Data System (ADS)

This paper describes the recent development of a low-noise, two-dimensional analog front-end ASIC for hybrid pixel imaging detectors. Based on the Open-IP LSI project, the ASIC is designed to meet a low-noise requirement of better than 100e (rms) with self-triggering capability. The ASIC is intended for the readout of pixel sensors utilizing silicon (Si) and cadmium telluride (CdTe) as detector materials for spectroscopic imaging observations in the X-ray and gamma-ray regions. The readout chip consists of a 4×4 matrix of identical 270?m×270?m pixel cells and was implemented with TSMC 0.35-?m CMOS technology. Each pixel cell contains a charge-sensitive amplifier, pole-zero cancellation circuit, shaper, comparator, and peak hold circuit. Preliminary testing of the ASIC achieved an 88e (rms) equivalent noise charge and a 25e/pF noise slope with power consumption of 150?W per pixel.

Kishishita, Tetsuichi; Ikeda, Hirokazu; Sakumura, Takuto; Tamura, Ken-Ichi; Takahashi, Tadayuki

2009-01-01

297

Optically Isolated ECG Amplifier with Baseline Stabilization.  

National Technical Information Service (NTIS)

An electrocardiographic (ECG) amplifier that is optically isolated and suitable for use in all environments has been developed and tested in 100 experiments involving immersed humans during exercise and rest. The amplifier has less than a 10 micro A curre...

W. H. Mints W. E. Long

1981-01-01

298

Low Temperature Low Noise SOS Mosfet Amplifier.  

National Technical Information Service (NTIS)

The patent application describes a MOSFET amplifier apparatus capable of operating with low noise levels at low temperatures. The amplifier apparatus is totally self-biased and integrally contains all required lines and cross-over connections.

R. S. Roner

1975-01-01

299

The Free Electron Laser Klystron Amplifier Concept  

Microsoft Academic Search

The simplest high gain free electron laser (FEL) amplifier concept is\\u000aproposed. A klystron amplifier has the useful property that the various\\u000aelectronic processes take place in separate portions of the amplifier, rather\\u000athan overlapping as in FEL amplifier with an uniform undulator. The klystron\\u000aconsists of two fundamental parts: succession of 2-3 cascades (modulator), and\\u000aan output undulator (radiator)

E. L. Saldin; E. A. Schneidmiller; M. V. Yurkov

2003-01-01

300

Quantum-Dot Semiconductor Optical Amplifiers  

Microsoft Academic Search

This paper reviews the recent progress of quantum-dot semiconductor optical amplifiers developed as ultrawideband polarization-insensitive high-power amplifiers, high-speed signal regenerators, and wideband wavelength converters. A semiconductor optical amplifier having a gain of > 25 dB, noise figure of 20 dBm, over the record widest bandwidth of 90 nm among all kinds of optical amplifiers, and also having a penalty-free output

T. Akiyama; M. Sugawara; Y. Arakawa

2007-01-01

301

A CMOS Tunable Transimpedance Amplifier  

Microsoft Academic Search

A tunable transimpedance amplifier (TIA) is presented in this letter. By incorporating a mechanism for gain and bandwidth tuning, the TIA can be adjusted to achieve optimum circuit performance with a lowest bit-error-rate (BER) for high-speed applications. The proposed circuit is implemented in a 0.18-mum CMOS process. Consuming a dc power of 34mW from a 2.0-V supply voltage, the fabricated

Huei-Yan Hwang; Jun-Chau Chien; Tai-Yuan Chen; Liang-Hung Lu

2006-01-01

302

Operational Amplifiers Animation/Presentation  

NSDL National Science Digital Library

This presentation, by Arizona State University, addresses operational amplifiers; their structure, construction and applications of the technology. The site is broken down into ten sections; these are: an introduction, terminal connections, op-amp internals, ideal op-amp equations, circuit analysis example, voltage follower, inverting configuration, non-inverting configuration, differentiators, and integrators. Overall, the site is flashy, but still informative presentation of this technology.

Holbert, Keith E.

2010-03-18

303

Electronically tuned UHF power amplifier  

Microsoft Academic Search

This electronically tunable UHF power amplifier (PA) is based upon a gallium-nitride (GaN) HEMT operated in class C. The gate input is tuned by two arrays of varactor diodes. The drain output is tuned by a three-stub tuner whose stub lengths are controlled by pin diodes. From 325 to 800 MHz (factor of 2.5:1), the PA delivers an output of

Frederick H. Raab

2011-01-01

304

Gyrotron amplifiers for plasma heating  

NASA Astrophysics Data System (ADS)

In the non-neutral, relativistic plasma Cyclotron Resonance Maser (CRM) instability, electrons gyrating in a uniform magnetic field interact with electromagnetic radiation. The action of the electric field of the radiation is to accelerate some electrons and decelerate others, depending on their location in the orbital phase. The accelerated electrons increase in momentum, gyro-radius and relativistic mass, and therefore drop in frequency and retard in phase. The opposite is true for decelerating electrons resulting in the formation of a phase bunch. If the gyrofrequency of the beam is slightly less than the wave frequency then the bunches move naturally into decelerating phase and reinforce the wave. This type of interaction has hitherto been successfully exploited in gyrotron oscillators. The research to be presented has built upon the fundamental breakthrough that occurred in gyro-amplifiers where the gain mechanism of the successful gyrotron oscillator has been exploited effectively in a Gyrotron Travelling Wave amplifier, Gyro-TWA. The design, construction and operation of a Gyro-TWA experiment will be presented. The amplifier achieved a peak power of 1.3MW, a saturated gain of 35dB in the frequency range of 8.4GHz to 10.2GHz with an efficiency of 30%.

Cross, Adrian; Whyte, Colin; He, Wenlong; Young, Alan; Robertson, Craig; Ronald, Kevin; Phelps, Alan

2008-11-01

305

Monolithic integrated Raman silicon lasers and amplifiers  

Microsoft Academic Search

In this paper, a chip-scale Raman silicon laser and amplifier based on a ring resonator architecture are presented. Lasing threshold and efficiency are significantly improved from the previous experiments. Much lower pump power and smaller foot print are needed for the ring resonator amplifier compared to Raman amplifier in linear configuration due to the resonance enhancement effect. The ring resonator

Haisheng Rong; Shengbo Xu; Ying-Hao Kuo; V. Sih; M. Paniccia; O. Cohen; O. Raday

2007-01-01

306

The Need for Flexibility in Amplifier Design  

Microsoft Academic Search

Improvements in detector resolution and increases in the sophistication of nuclear experiments have placed an entirely new emphasis on linear amplifier design. Just a few years ago it was necessary to have specialized amplifiers to deal with each specific problem. The lack of flexibility now plaguing most existing linear pulse amplifying systems is often quite annoying to the user. Invariably,

W. W. Goldsworthy

1963-01-01

307

Alternative Dopants for Silica Fibre Amplifiers  

Microsoft Academic Search

Optical telecommunications systems benefit from well developed and efficient optical fibre amplifiers operating on relatively narrow bands. Recent improvements in silica fibres broadened their transmission window, allowing telecommunications almost anywhere within the 800 - 1700 nm window. Although already available amplified bandwidth is not fully used yet, long term basic research is needed to identify innovative, cheap, reliable fiber amplifiers

B. Dussardier; W. Blanc

2007-01-01

308

Class E amplifier with inductive clamp circuit  

Microsoft Academic Search

A class E RF amplifier, which can operate into any load conditions without need for other additional circuitry to protect transistors, is introduced. This is provided by a new topology which incorporates inductive clamp circuitry to the basic class E amplifier circuit. Class E amplifiers with this topology can be used in plasma applications where the load conditions are dynamic.

Abdullah Eroglu; Dan Lincoln

2005-01-01

309

New topology for Class E amplifiers  

Microsoft Academic Search

A Class E RF amplifier, which can operate into any load conditions without need for other additional circuitry to protect transistors, is introduced. This is provided by the new topology, which is called an inductive clamp. Our topology incorporates inductive clamp circuitry to the basic Class E amplifier circuit and it has all the benefits of Class E amplifiers. Additionally,

A. Eroglu; D. Lincoln; A. Radomski; Y. Chawla

2007-01-01

310

Kilohertz Femtosecond Ti: Sapphire Regenerative Amplifier.  

National Technical Information Service (NTIS)

To have capabilities in the near-infrared, we proposed to develop a Ti:S regenerative amplifier operating at one kilohertz. This amplifier was developed to amplify the pulses from our femtosecond Ti:S laser oscillator to the 2-3 mu J/pulse energy level. T...

N. Peyghamberian B. McGinnis

1995-01-01

311

AC instrumentation amplifier for bioimpedance measurements  

Microsoft Academic Search

The input impedance and common-mode rejection ratio requirements for an amplifier for bioimpedance measurements are analyzed, considering the capacitive components of the electrode-skin contact impedance. An AC-coupled instrumentation amplifier that fulfills those requirements, and provides both interference and noise reduction and a zero phase shift over a wide frequency band without using broadband operational amplifiers, is described.

R. Pallas-Areny; J. G. Webster

1993-01-01

312

Modeling erbium-doped fiber amplifiers  

Microsoft Academic Search

Erbium-doped fiber amplifiers are modeled using the propagation and rate equations of a homogeneous two-level laser medium. Numerical methods are used to analyze the effects of optical modes and erbium confinement on amplifier performance, and to calculate both the gain and amplified spontaneous emission (ASE) spectra. Fibers with confined erbium doping are completely characterized from easily measured parameters: the ratio

C. Randy Giles; Emmanuel Desurvire

1991-01-01

313

A CMOS integrating amplifier for the PHENIX Ring Imaging Cherenkov detector  

SciTech Connect

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 1,000:1. 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-bit 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.

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

1998-06-01

314

A CMOS Integrating Amplifier for the PHENIX Ring Imaging Cherenkov detector  

SciTech Connect

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.

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

315

Cryogenic CMOS circuits for single charge digital readout.  

SciTech Connect

The readout of a solid state qubit often relies on single charge sensitive electrometry. However the combination of fast and accurate measurements is non trivial due to large RC time constants due to the electrometers resistance and shunt capacitance from wires between the cold stage and room temperature. Currently fast sensitive measurements are accomplished through rf reflectrometry. I will present an alternative single charge readout technique based on cryogenic CMOS circuits in hopes to improve speed, signal-to-noise, power consumption and simplicity in implementation. The readout circuit is based on a current comparator where changes in current from an electrometer will trigger a digital output. These circuits were fabricated using Sandia's 0.35 {micro}m CMOS foundry process. Initial measurements of comparators with an addition a current amplifier have displayed current sensitivities of < 1nA at 4.2K, switching speeds up to {approx}120ns, while consuming {approx}10 {micro}W. I will also discuss an investigation of noise characterization of our CMOS process in hopes to obtain a better understanding of the ultimate limit in signal to noise performance.

Gurrieri, Thomas M.; Longoria, Erin Michelle; Eng, Kevin; Carroll, Malcolm S.; Hamlet, Jason R.; Young, Ralph Watson

2010-03-01

316

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

Microsoft Academic Search

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.

Dao Thi Ngoc Anh; Prerna Singh; Cheshta Shankar; Derrick Mott; Shinya Maenosono

2011-01-01

317

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

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.

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

318

Take Charge!  

NSDL National Science Digital Library

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.

Integrated Teaching And Learning Program

319

Electrodeless determination of the trap density, decay kinetics, and charge separation efficiency of dye-sensitized nanocrystalline TiO(2).  

PubMed

We have studied photoinduced charge separation in a bare, 3.4 microm thick layer of nanocrystalline ("nc") anatase TiO(2) and an nc-TiO(2) layer coated with free-base 5,10,15,20-tetrakis(4-carboxyphenyl) porphyrin (H(2)TPPC) using the electrodeless flash-photolysis time-resolved microwave-conductivity technique (FP-TRMC). Photoconductivity transients, resulting from the formation of mobile, conduction band electrons in the semiconductor have been measured on excitation with 3 ns pulses of UV (300 nm) and visible (410-700 nm) light. The product of the yield of formation of mobile charge carriers, phi, and the sum of their mobilities, Sigmamicro, has been determined from the maximum conductivity for light intensities varying from approximately 10(12) to approximately 10(16) photons/cm(2)/pulse. For the bare nc-TiO(2) layer at 300 nm and the coated layer at all wavelengths, phiSigmamicro initially increased with increasing intensity, reached a maximum, and eventually decreased at high intensities. The initial increase is attributed to the gradual filling of (surface) electron trapping sites. This effect was absent when the samples were continuously illuminated with background irradiation at 300 nm with an intensity of 6 x 10(13) photons/cm(2)/s (40 microW/cm(2)), thereby presaturating the trapping sites prior to the laser pulse. The trap-free mobility of electrons within these 9 nm nanoparticles is estimated to be 0.034 cm(2)/Vs at 9 GHz. The eventual decrease in phiSigmamicro at intensities corresponding to an electron occupancy of more than one electron per particle is unaffected by background illumination, and is attributed to a decrease in micro due to electron-electron interactions within the semiconductor particles. The photoconductivity action spectrum of the coated nc-TiO(2) layer closely followed the photon attenuation spectrum in the visible of the porphyrin, with a charge separation efficiency per absorbed photon of 18% at the Soret band maximum. The after-pulse decay of the photoconductivity showed a power law behavior over a time scale of nanoseconds to several hundreds of microseconds, which is attributed to multiple trapping and detrapping events at chemical or physical defects within the semiconductor matrix. PMID:15198609

Kroeze, Jessica E; Savenije, Tom J; Warman, John M

2004-06-23

320

NIF/LMJ prototype amplifier mechanical design  

SciTech Connect

Amplifier prototypes for the National Ignition Facility and the Laser Megajoule will be tested at Lawrence Livermore National Laboratory. The prototype amplifier, which is an ensemble of modules from LLNL and Centre d`Etudes de Limeil-Valenton, is cassette-based with bottom access for maintenance. A sealed maintenance transfer vehicle which moves optical cassettes between the amplifier and the assembly cleanroom, and a vacuum gripper which holds laser slabs during cassette assembly will also be tested. The prototype amplifier will be used to verify amplifier optical performance, thermal recovery time, and cleanliness of mechanical operations.

Horvath, J.

1996-10-01

321

Digitally programmable composite operational amplifier applications  

NASA Astrophysics Data System (ADS)

In this study, CMOS implementation of composite operational amplifiers onto a single chip is examined. Composite operational amplifiers are realized by interconnecting two or more single operational amplifiers in any one of four high performance circuit topologies. These high performance topologies result in composite operational amplifiers having useful bandwidths that are significantly larger than those associated with their constituent operational amplifiers without sacrificing closed loop gain. Computer simulations using PSPICE are compared with experimental results for performance evaluation. As an application, a multiple feedback bandpass filter implementation is examined.

Crowell, Ronald A.

1993-09-01

322

Charge sniffer for electrostatics demonstrations  

NASA Astrophysics Data System (ADS)

An electronic electroscope with a special design for demonstrations and experiments on static electricity is described. It operates as an electric charge sniffer by detecting slightly charged objects when they are brought to the front of its sensing electrode. The sniffer has the advantage of combining high directional sensitivity with a logarithmic bar display. It allows for the identification of electric charge polarity during charge separation by friction, peeling, electrostatic induction, batteries, or secondary coils of power transformers. Other experiments in electrostatics, such as observing the electric field of an oscillating dipole and the distance dependence of the electric field generated by simple charge configurations, are also described.

Dinca, Mihai P.

2011-02-01

323

HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.  

SciTech Connect

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.

BEN-ZVI, ILAN, DAYRAN, D.; LITVINENKO, V.

2005-08-21

324

Alternating cascade of spectrally different erbium-doped fiber amplifiers for link-loss-insensitive long-haul WDM transmission  

Microsoft Academic Search

This paper numerically investigates a cascade of erbium-doped fiber amplifiers (EDFAs) with different spectral characteristics in an alternating scheme. Thereby, in a transmission band with appropriate spectral properties (1544-1550 nm), the sensitivity of optically amplified long-haul WDM transmission links on the span loss between amplifiers can be reduced to that of single-channel systems. This may be as much as an

Johan Nilsson; Bozena Jaskorzynska

1999-01-01

325

NIF Capsule Sensitivity to Drive Asymmetry  

SciTech Connect

Proposed NIF ICF capsules are sensitive to asymmetries resulting from radiation drive and capsule imperfections. Capsule imperfections are amplified by the Rayleigh-Taylor and Richtmeyer-Meshkoff instabilities, and pose a risk at mode numbers in the range of 20 to 100. Radiation drive asymmetries are also amplified by these hydrodynamic instabilities, and pose a danger at modes below 10. Previous work has mostly concentrated on quantifying the sensitivity to capsule imperfections. Here we concentrate on characterizing the sensitivity to drive asymmetries.

Pollaine, S; Amendt, P; Haan, S; Herrmann, M; Jones, O; Suter, L

2003-09-19

326

Pre-amplifier with multi-stage feedback  

NASA Astrophysics Data System (ADS)

A circuit for amplifying an input signal comprises an operational amplifier, a dual operational amplifier, and a buffering operational amplifier all cascaded in the aforementioned order. The first operational amplifier amplifies the input signal with minimum noise degradation, is set up as a non-inverting amplifier stage, and has a local negative feedback loop comprising a resistor and capacitor in parallel. The dual operational amplifier has two amplifying devices. One device forms a second amplifying stage which increases the gain of the pre-amplified input signal and has a local negative feedback loop comprising a resistor.

Hagerty, James D.

1994-03-01

327

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.

2009-11-23

328

Amplified terminal protection assay of small molecule/protein interactions via a highly characteristic solid-state Ag/AgCl process.  

PubMed

In this work, we describe a new sensitive strategy for electrochemical detection of protein via small molecule/protein interactions. This assay is based on a terminal protection mechanism that small molecule-linked single-stranded DNA (ssDNA) is protected against hydrolysis by exonuclease I when the target protein is captured by the corresponding small molecule recognition element. Positively charged gold nanoparticles (AuNPs) are attached to the termini-protected and negatively charged ssDNA through electrostatic interactions. Subsequent AuNP-catalyzed silver enhancement followed by a highly characteristic and sensitive solid-state Ag/AgCl process is introduced to the sensing platform to amplify the signal output. By combining the amplification ability resulting from the silver deposition on the surface-captured AuNPs with the inherent high sensitivity of the electrochemical solid-state Ag/AgCl process, our method expands its range to the detection of macromolecules that bind to specific small molecules and enables low picomolar detection of protein. As a model of biotin/streptavidin interaction, a detection limit of 10 pM for streptavidin is readily achieved with desirable sensitivity and specificity, which indicates that the terminal protection assay coupled with the electrochemical solid-state Ag/AgCl process can offer a promising platform for the determination of various of types of proteins or small molecule-protein interactions. PMID:23274192

Wang, Qiong; Jiang, Bingying; Xu, Jin; Xie, Jiaqing; Xiang, Yun; Yuan, Ruo; Chai, Yaqin

2012-12-04

329

Pre-amplifier with multi-stage feedback  

NASA Astrophysics Data System (ADS)

A circuit for amplifying an input signal comprises an operational amplifier, a dual operational amplifier, and a buffering operational amplifier all cascaded in the afore-mentioned order. The first operational amplifier amplifies the input signal with minimum noise degradation, is set up as a non-inverting amplifier stage, and has a local negative feedback loop comprising a resistor and capacitor in parallel. The dual operational amplifier has two amplifying devices. One device forms a second amplifying stage which increases the gain of the pre-amplified input signal and has a local negative feedback loop comprising a resistor. The other device is a third operational amplifier which combines with the buffering operational amplifier to form an amplifying and buffering stage. The third operational amplifier connects in series to the output of the second amplifying stage. The buffering operational amplifier connects in series to the output of the third operational amplifier and buffers the amplified signal at this output. The amplifying and buffering stage has a two-stage feedback loop comprising a resistor connected between the output of the buffering operational amplifier and the inventing input of the third operational amplifier. A four-stage feedback loop includes a resistor and capacitor in parallel and connects between the output of the buffering operational amplifier and the inverting input of the first operational amplifier.

Hagerty, James D.

1994-12-01

330

Teaching the common emitter amplifier  

NASA Astrophysics Data System (ADS)

If one wishes to teach some device electronics in schools it will have to be very limited. It is not productive to measure all the common emitter and common base characteristics of the bipolar transistor as required by at least one A-level syllabus. To do so wastes pupil time and leads to considerable confusion. Nor should the study be extended to cover for example all possible methods of biasing a common emitter amplifier. What is needed is a 'bare bones' approach, enough to give a first step towards understanding the subject. A case can be made for the study of an operational amplifier in electronic circuits, treating it as an ideal electronic 'device'. However, the author's personal feeling is that the study of a single active device such as the bipolar transistor provides a firm background from which students can extend their study of electronics and has the advantage in a physics course that from there it is a very short step to discuss a simple model for the internal mechanisms of semiconductor devices.

Ellse, Mark D.

1984-11-01

331

Half-Octave Shift in Mammalian Hearing Is an Epiphenomenon of the Cochlear Amplifier  

PubMed Central

The cochlear amplifier is a hypothesized positive feedback process responsible for our exquisite hearing sensitivity. Experimental evidence for or against the positive feedback hypothesis is still lacking. Here we apply linear control theory to determine the open-loop gain and the closed-loop sensitivity of the cochlear amplifier from available measurements of basilar membrane vibration in sensitive mammalian cochleae. We show that the frequency of peak closed-loop sensitivity is independent of the stimulus level and close to the characteristic frequency. This implies that the half-octave shift in mammalian hearing is an epiphenomenon of the cochlear amplifier. The open-loop gain is consistent with positive feedback and suggests that the high-frequency cut-off of the outer hair cell transmembrane potential in vivo may be necessary for cochlear amplification.

Ramamoorthy, Sripriya; Nuttall, Alfred L.

2012-01-01

332

Stem-loop oligonucleotide beacons as switches for amplifying-fluorescent-polymer-based biological warfare sensors  

Microsoft Academic Search

Sensors that are exceptionally sensitive with real-time outputs and minimal consumption of reagents are needed to continuously monitor air and water against bioterrorist incidents. Amplifying fluorescent polymers (AFP) provide exceptionally sensitive real-time reagentless sensor platforms as applied to detection of nitroaromatic explosives. This platform technology has the potential to be adapted to detect biological warfare (BW) agents by covalently attaching

Kenneth D. Clinkenbeard; Akhilesh Ramachandran; Jerry R. Malayer; Joong Ho Moon; Lawrence F. Hancock

2003-01-01

333

Evaluation of SHARP Signal System for Enzymatic Detection of Amplified Hepatitis B Virus DNA  

Microsoft Academic Search

The sensitivity, specificity, reproducibility, detection level, and quantification potential of the SHARP Signal System for enzymatic detection of amplified hepatitis B virus (HBV) DNA in clinical samples were evaluated by testing 104 samples in parallel in a SHARP PCR, an in-house HBV PCR, and a dot blot hybridization assay for semiquantification. SHARP PCR showed a sensitivity of 100%, a specificity

ELIZABETH VALENTINE-THON

334

An enhanced glucose biosensor using charge transfer techniques.  

PubMed

An enhanced glucose biosensor based on a charge transfer technique glucose sensor (CTTGS) is described and demonstrated experimentally. In the proposed CTTGS, which is accumulation method (d-gluconate+H(+)) ion perception system, the quality of output signal with "signal integration cycles" is high. With the proposed CTTGS it is possible to amplify the sensing signals without an external amplifier by using an accumulation cycle. It can be supposed that measurements of small (d-gluconate+H(+)) ion fluctuation are difficult by ion-sensitive field effect transistor (ISFET) because the theoretical maximum sensitivity is only 59 mV/pH and the small output signals are buried in the 1/f noise component of the metal-insulator-semi-conductor field-effect transistor (MISFET). Therefore, the CTTGS has many advantages, such as high sensitivity, high accuracy, high signal-to-noise ratio (SNR), and has been successfully demonstrated using a charge transfer technique. The CTTGS exhibited excellent performance for glucose with a large span (1445 mV) and good reproducibility. Moreover, the CTTGS has good sensitivity in this range of 7.22mV/mM, a lower detection limit of about 0.01 mM/L and an upper detection limit of about 200 mM/L compared with amperometric glucose analysis which has been studied recently. Under optimum conditions, the proposed CTTGS exceeds the performance of the widely used ISFET glucose sensor. The sensitivity of the CTTGS (7.22 mV/mM) was seven times higher than that of the ISFET (1 mV/mM). Furthermore, the sensitivity obtained for human glucose levels was 29.06 mV/mM with a non-linear error of +/-0.27%; the linearity is y=0.0294x+1.8612 and R(2)=0.9999, which is acceptable for clinical application. Real sample analysis is investigated in blood glucose level by our developed CTTGS ISFET system. PMID:18640027

Lee, Seung-Ro; Sawada, Kazuaki; Takao, Hidekuni; Ishida, Makoto

2008-06-17

335

Three-dimensional evaluation of energy extraction in output cavities of klystron amplifiers  

Microsoft Academic Search

An accurate three-dimensional analysis of the performance of output gaps in klystron amplifiers was carried out. The parameters investigated were: beam radius, perveance, output gap angle, output gap peak voltage, RF phase, magnetic field, and beam interception. A new, accurate method for computing space-charge forces between axially and radially deformable rings was developed. Rigorous expressions for electric and magnetic fields

HENRY G. KOSMAHL; LYNN U. ALBERS

1973-01-01

336

Simple two-electrode biosignal amplifier.  

PubMed

A simple, cost effective circuit for a two-electrode non-differential biopotential amplifier is proposed. It uses a 'virtual ground' transimpedance amplifier and a parallel RC network for input common mode current equalisation, while the signal input impedance preserves its high value. With this innovative interface circuit, a simple non-inverting amplifier fully emulates high CMRR differential. The amplifier equivalent CMRR (typical range from 70-100 dB) is equal to the open loop gain of the operational amplifier used in the transimpedance interface stage. The circuit has very simple structure and utilises a small number of popular components. The amplifier is intended for use in various two-electrode applications, such as Holter-type monitors, defibrillators, ECG monitors, biotelemetry devices etc. PMID:16594298

Dobrev, D; Neycheva, T; Mudrov, N

2005-11-01

337

A low noise FET with integrated charge restoration for radiation detectors  

SciTech Connect

A novel pulsed, non-optical, reset technique for use in charge sensitive amplifiers and radiation detectors is described. The first stage FET and charge restoration are integrated into one 5-terminal device labelled the Pentafet. A pulse of minority carriers is injected directly into the channel of the FET. The technique is fast and there are no after effects on the operation of the FET. Very low noise performance is achieved even at high count rates. The high energy rate product capability of the device is demonstrated by analyzing Mn x-rays in the presence of high energy electrons from an Sr 90 beta source and in a transmission electron microscope (TEM).

Nashoishibi, T.; White, G. (Link Analytical Ltd., Halifax Road, High Wyucombe, Bucks, HP 123SE (GB))

1990-04-01

338

Development of 2 W UHF power amplifier  

Microsoft Academic Search

This paper describes the development of a three-stage transistor amplifier delivering a power output of 2 W in the frequency range 720 MHz-820 MHz. The input and output matching networks of the amplifier are realized on microstrips. Design of a power stage is discussed in detail. The amplifier meets all the design goals e.g., 2 W power output, bandwidth, ease

D. Rustogi; V. K. Garg; R. V. Singh

1977-01-01

339

An ultralow noise amplifier for superconductive detectors  

Microsoft Academic Search

The design and construction of an AC-coupled, ultralow noise amplifier (equivalent input noise voltage En=0.33 nV\\/ square root Hz, optimum source impedance 1 k Omega at 100 kHz) is presented. The amplifier employs nine Sony 2SK 152-4 JFETS in parallel to yield the low noise result. Measurements were taken to characterize the amplifier's bandwidth, the additive voltage noise versus frequency,

G. M. Gutt; J. S. Kim; M. R. Condron; J. M. Lockhart; B. Muhlfelder

1991-01-01

340

Antares prototype power amplifier. Final report  

Microsoft Academic Search

A new power amplifier design was devised for Antares, the Los Alamos Scientific Laboratory 100-kJ COâ laser system. To test this design, a cold-cathode gun, a high-voltage test vehicle, and a prototype power amplifier were designed, built, and tested. This report describes these devices and the experimental work that demonstrated the predicted performance of the new amplifier design.

W. T. Leland; G. York; T. Ganley; D. Swanson; G. Loda; E. Yavornik; K. Riepe; R. Lindstrand; J. Comly

1978-01-01

341

Gyro-amplifiers modeling with MAGY  

Microsoft Academic Search

Recent modeling results of several experiments on gyroklystron amplifier at the Naval Research Laboratory are presented. Modeling was performed using the quasi three-dimensional, self-consistent code MAGY[1] . Amplifiers in both Ka- and W-bands have been studied [2,3]. Using known experimental input parameters, code-predicted salient amplifier performance characteristics, e.g. efficiency, bandwidth, drive curve, have been found to be in good agreement

Baruch Levush; Khanh Nguyen; Moti Botton; Alexander Vlasov Antonsen Jr.

1999-01-01

342

Ping-pong auto-zero amplifier with glitch reduction  

DOEpatents

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.

Larson, Mark R. (Maple Grove, MN)

2008-01-22

343

A high-power 95 GHz gyro-TWT amplifier  

SciTech Connect

The need for radar systems with greater resolution has led to renewed interest in the development of efficient high-power amplifiers at 95 GHz. The gyro-TWT is capable of producing high power with the added attraction of having lower ohmic loading on the smooth fast-wave interaction circuit than conventional slow-wave sources. We have completed a comprehensive desip of a 95 GHz gyro-TWT amplifier that is capable of producing 120 kill of output power with an efficiency of 30%, a saturated gain of 38 dB and an instantaneous bandwidth of over 5 GHz. Our concept uses an annular beam produced by a MIG electron source and operates in the TE[sub 5,1] cylindrical waveguide mode. Realistic beam parameters from gun simulations were, included in our efficiency calculations. In addition, our design includes the use of a compact superconducting magnet, quasi-optical input and output couplers and a sever to supress oscillations. The overall mechanical design shows that a compact, lightweight amplifier with adequate beam clearance is possible. This report also includes a study of a gyro-TWT using a solid on-axis beam from a Pierce-wiggler electron source coupling with a TE[sub 1,n] waveguide mode. Nonlinear models indicated that an efficient interaction with the waveguide mode was possible, however, beam simulations indicated that the high current density beam had large internal space charge forces that caused a substantial degradation of the beam quality.

Kreischer, K.E.; Basten, M.; Blank, M.; Danly, B.G.; Guss, W.C.; Temkin, R.J.

1992-07-01

344

A high-power 95 GHz gyro-TWT amplifier  

SciTech Connect

The need for radar systems with greater resolution has led to renewed interest in the development of efficient high-power amplifiers at 95 GHz. The gyro-TWT is capable of producing high power with the added attraction of having lower ohmic loading on the smooth fast-wave interaction circuit than conventional slow-wave sources. We have completed a comprehensive desip of a 95 GHz gyro-TWT amplifier that is capable of producing 120 kill of output power with an efficiency of 30%, a saturated gain of 38 dB and an instantaneous bandwidth of over 5 GHz. Our concept uses an annular beam produced by a MIG electron source and operates in the TE{sub 5,1} cylindrical waveguide mode. Realistic beam parameters from gun simulations were, included in our efficiency calculations. In addition, our design includes the use of a compact superconducting magnet, quasi-optical input and output couplers and a sever to supress oscillations. The overall mechanical design shows that a compact, lightweight amplifier with adequate beam clearance is possible. This report also includes a study of a gyro-TWT using a solid on-axis beam from a Pierce-wiggler electron source coupling with a TE{sub 1,n} waveguide mode. Nonlinear models indicated that an efficient interaction with the waveguide mode was possible, however, beam simulations indicated that the high current density beam had large internal space charge forces that caused a substantial degradation of the beam quality.

Kreischer, K.E.; Basten, M.; Blank, M.; Danly, B.G.; Guss, W.C.; Temkin, R.J.

1992-07-01

345

Charge Domain Interlace Scan Implementation in a CMOS Image Sensor  

Microsoft Academic Search

This paper presents the first CMOS image sensor which implements a charge domain interlacing principle to improve the signal-to-noise ratio (SNR) under equal exposure condition (integration time and light intensity). Inspired by the shared amplifier pixel structure, a novel pixel is designed to fit the charge domain interlacing principle, which works in field integration and frame integration mode. The designed

Yang Xu; Adri J. Mierop; Albert J. P. Theuwissen

2011-01-01

346

Charging machine  

DOEpatents

A charging machine for loading fuel slugs into the process tubes of a nuclear reactor includes a tubular housing connected to the process tube, a charging trough connected to the other end of the tubular housing, a device for loading the charging trough with a group of fuel slugs, means for equalizing the coolant pressure in the charging trough with the pressure in the process tubes, means for pushing the group of fuel slugs into the process tube and a latch and a seal engaging the last object in the group of fuel slugs to prevent the fuel slugs from being ejected from the process tube when the pusher is removed and to prevent pressure liquid from entering the charging machine.

Medlin, John B. (Newark, DE)

1976-05-25

347

Influence of amplified spontaneous emission on gain lifetime in high-aperture Ti:sapphire amplifiers.  

PubMed

We demonstrate that by lowering gain lifetime, transverse amplified spontaneous emission imposes practical limit on usable aspect ratio of large-aperture amplifiers in a high-energy Ti:sapphire system. PMID:23670763

Yanovsky, Victor; Krushelnick, Karl

2013-04-10

348

Combined application of dispersive liquid-liquid microextraction based on the solidification of floating organic droplets and charged aerosol detection for the simple and sensitive quantification of macrolide antibiotics in human urine.  

PubMed

A novel analytical method combining dispersive liquid-liquid microextraction based on the solidification of floating organic droplets (DLLME-SFO) and liquid chromatography with charged aerosol detection (LC-CAD) was established. For the first time, CAD was applied for the detection of macrolide antibiotics lacking chromophores. Parameters influencing the microextraction efficiency were systematically investigated, and the optimized microextraction conditions yielded high enrichment factors in the range of 60-106. The combined application of DLLME-SFO and LC-CAD provided the sensitivity of the method, expressed as the limit of detection (LOD), as low as 10 to 40ngmL(-1) and intra-day and inter-day precisions below 8.7% and 12.6%, respectively. The measured absolute recovery values were approximately 100%, indicating that the extraction efficiency was very high. Direct comparisons of the liquid-liquid extraction and organic solvent precipitation methods demonstrated that the proposed method was more sensitive, specific, rapid, and environmentally friendly for the determination of five macrolide antibiotics in human urine. The results suggest that the combined use of DLLME-SFO and LC-CAD may be applicable to the analysis of various compounds with poor to no chromophores in complex matrices. PMID:24013122

Jia, Shaodong; Li, Jing; Park, So-Ra; Ryu, Yeonsuk; Park, Il Ho; Park, Jeong Hill; Hong, Soon-Sun; Kwon, Sung Won; Lee, Jeongmi

2013-08-16

349

Using SQUIDs to Detect Charge in Cryogenic Germanium Detectors  

NASA Astrophysics Data System (ADS)

This paper describes an impedance matching network which allows charge impulses to be measured by a SQUID amplifier with an RMS charge noise of less than 100 e, assuming the SQUID amplifier has a current noise of 2 pA/sqrt{Hz}, and the current pulse has a duration of about 1 ?s or shorter. The component values are provided for an example system which has an RMS charge noise of 91 e, assuming all dissipative circuit elements are cooled to a temperature of 100 mK.

Moffatt, R. A.; Cabrera, B.; Kadribasic, F.; Pyle, M.; Wesenberg, D.; Yen, J. J.; Young, B. A.

2012-06-01

350

Serial time-encoded amplified imaging for real-time observation of fast dynamic phenomena.  

PubMed

Ultrafast real-time optical imaging is an indispensable tool for studying dynamical events such as shock waves, chemical dynamics in living cells, neural activity, laser surgery and microfluidics. However, conventional CCDs (charge-coupled devices) and their complementary metal-oxide-semiconductor (CMOS) counterparts are incapable of capturing fast dynamical processes with high sensitivity and resolution. This is due in part to a technological limitation-it takes time to read out the data from sensor arrays. Also, there is the fundamental compromise between sensitivity and frame rate; at high frame rates, fewer photons are collected during each frame-a problem that affects nearly all optical imaging systems. Here we report an imaging method that overcomes these limitations and offers frame rates that are at least 1,000 times faster than those of conventional CCDs. Our technique maps a two-dimensional (2D) image into a serial time-domain data stream and simultaneously amplifies the image in the optical domain. We capture an entire 2D image using a single-pixel photodetector and achieve a net image amplification of 25 dB (a factor of 316). This overcomes the compromise between sensitivity and frame rate without resorting to cooling and high-intensity illumination. As a proof of concept, we perform continuous real-time imaging at a frame speed of 163 ns (a frame rate of 6.1 MHz) and a shutter speed of 440 ps. We also demonstrate real-time imaging of microfluidic flow and phase-explosion effects that occur during laser ablation. PMID:19407796

Goda, K; Tsia, K K; Jalali, B

2009-04-30

351

Conceptual designs of a 50 nm FEL (free-electron laser) oscillator and a 20-40 nm SASE (self-amplified spontaneous emission) amplifier  

SciTech Connect

This paper consists of two parts: the conceptual design and optical performance characteristics of a grazing angle-of-incidence ring resonator utilizing multifaceted metal mirrors for use with a 50 nm rf-linac-driven XUV FEL oscillator; and electron beam and wiggler requirements for a self-amplified spontaneous emission (SASE) amplifier to produce high power in the 20 to 40 nm wavelength range. The basis for these studies is the 3-d FEL simulation code FELEX which is used to derive tolerances on mirror figure and thermal distortion, alignment sensitivity, and alternative output coupling methods. The sensitivity of the output characteristics of an XUV FEL SASE amplifier to wiggler field errors is also studied. 17 refs., 8 figs., 2 tabs.

Goldstein, J.C.; McVey, B.D.; Elliott, C.J.

1987-01-01

352

Total Charge Movement per Channel  

PubMed Central

One measure of the voltage dependence of ion channel conductance is the amount of gating charge that moves during activation and vice versa. The limiting slope method, introduced by Almers (Almers, W. 1978. Rev. Physiol. Biochem. Pharmacol. 82:96–190), exploits the relationship of charge movement and voltage sensitivity, yielding a lower limit to the range of single channel gating charge displacement. In practice, the technique is plagued by low experimental resolution due to the requirement that the logarithmic voltage sensitivity of activation be measured at very low probabilities of opening. In addition, the linear sequential models to which the original theory was restricted needed to be expanded to accommodate the complexity of mechanisms available for the activation of channels. In this communication, we refine the theory by developing a relationship between the mean activation charge displacement (a measure of the voltage sensitivity of activation) and the gating charge displacement (the integral of gating current). We demonstrate that recording the equilibrium gating charge displacement as an adjunct to the limiting slope technique greatly improves accuracy under conditions where the plots of mean activation charge displacement and gross gating charge displacement versus voltage can be superimposed. We explore this relationship for a wide variety of channel models, which include those having a continuous density of states, nonsequential activation pathways, and subconductance states. We introduce new criteria for the appropriate use of the limiting slope procedure and provide a practical example of the theory applied to low resolution simulation data.

Sigg, Daniel; Bezanilla, Francisco

1997-01-01

353

Transfer matrix analysis of the amplified spontaneous emission of DFB semiconductor laser amplifiers  

Microsoft Academic Search

Analytical expressions ware derived for the amplified spontaneous emission of a DFB semiconductor laser amplifier with reflective cavity ends. The analysis is extended to a multisection DFB structure including a phase-shifted DFB semiconductor laser amplifier. It is shown that the spontaneous emission power per unit frequency bandwidth emitted from one facet is proportional to the transmission gain and to a

T. Makino; J. Glinski

1988-01-01

354

Double Integrator Magnetic Amplifier Output Circuit.  

National Technical Information Service (NTIS)

The magnetic amplifier has an integrating circuit adapted to produce a sinusoidal output voltage. Two properly rated integrating circuits are applied to the output of a push-pull magnetic amplifier. An output current may be provided flowing through the ex...

W. A. Geyher

1965-01-01

355

Varactor Tuners Eliminated an RF Amplifier  

Microsoft Academic Search

There is an urgent demand for low noise varactor tuners for use in TV receivers to meet the requirements of FCC rules. The RF amplifier has been frequently eliminated in mechanical tuners now in use, resulting in good cross-modulation characteristics and low cost. However, the elimination of the RF amplifier has not been attained in varactor tuners, because of high

Tohru Hara; Ikuo Niikura

1979-01-01

356

A micro strain gauge with mechanical amplifier  

Microsoft Academic Search

A passive micro strain gauge with a mechanical amplifier has been designed, analyzed, and tested. The mechanical amplifier provides a high gain such that residual strain in thin films can be directly measured under an optical microscope. This strain gauge can be in situ fabricated with active micro sensors or actuators for monitoring residual strain effects, and both tensile and

Liwei Lin; Albert P. Pisano; Roger T. Howe

1997-01-01

357

Gain flattening in a Raman amplifier  

Microsoft Academic Search

In designing WDM (Wavelength Division Multiplexing) systems, it is required that gain flattening must not be ignored. In this work, it is ensured that a Raman amplifier provides flat gain in a wide band, by analysis. The effects of the wavelength and the power of the pump laser on the gain flattening of a Raman amplifier are investigated. Using a

Mehmet Unal; Yusuf Hacisalihoglu; N. Ozlem Unverdi

2011-01-01

358

Analysis and design of feedforward power amplifier  

Microsoft Academic Search

A linear power amplifier is particularly emphasized on the system using a linear modulation scheme, because intermodulation distortion which causes adjacent channel interference and co-channel interference is mostly generated in a nonlinear power amplifier. In this paper, parameters of a linearization loop, such as an amplitude imbalance, a phase imbalance and a delay mismatch, are fully analyzed to get a

Sang-Gee Kang; Il-Kyoo Lee; Ki-Suk Yoo

1997-01-01

359

Post pulse shutter for laser amplifier  

DOEpatents

Apparatus and method for quickly closing off the return path for an amplified laser pulse at the output of an amplifier so as to prevent damage to amplifiers and other optical components appearing earlier in the chain by the return of an amplified pulse. The apparatus consists of a fast retropulse or post pulse shutter to suppress target reflection and/or beam return. This is accomplished by either quickly placing a solid across the light transmitting aperture of a component in the chain, such as a spatial filter pinhole, or generating and directing a plasma with sufficiently high density across the aperture, so as to, in effect, close the aperture to the returning amplified energy pulse.

Bradley, Laird P. (Livermore, CA); Carder, Bruce M. (Antioch, CA); Gagnon, William L. (Berkeley, CA)

1981-01-01

360

Dual-range linearized transimpedance amplifier system  

SciTech Connect

A transimpedance amplifier system is disclosed which simultaneously generates a low-gain output signal and a high-gain output signal from an input current signal using a single transimpedance amplifier having two different feedback loops with different amplification factors to generate two different output voltage signals. One of the feedback loops includes a resistor, and the other feedback loop includes another resistor in series with one or more diodes. The transimpedance amplifier system includes a signal linearizer to linearize one or both of the low- and high-gain output signals by scaling and adding the two output voltage signals from the transimpedance amplifier. The signal linearizer can be formed either as an analog device using one or two summing amplifiers, or alternately can be formed as a digital device using two analog-to-digital converters and a digital signal processor (e.g. a microprocessor or a computer).

Wessendorf, Kurt O. (Albuquerque, NM)

2010-11-02

361

Post pulse shutter for laser amplifier  

DOEpatents

Disclosed are an apparatus and method for quickly closing off the return path for an amplified laser pulse at the output of an amplifier so as to prevent damage to amplifiers and other optical components appearing earlier in the chain by the return of an amplified pulse. The apparatus consists of a fast retropulse or post pulse shutter to suppress target reflection and/or beam return. This is accomplished by either quickly placing a solid across the light transmitting aperture of a component in the chain, such as a spatial filter pinhole, or generating and directing a plasma with sufficiently high density across the aperture, so as to, in effect, close the aperture to the returning amplified energy pulse. 13 figs.

Bradley, L.P.; Carder, B.M.; Gagnon, W.L.

1981-03-17

362

Single-component chemically amplified resist materials for electron-beam and x-ray lithography  

Microsoft Academic Search

Copolymers of 4-tert-butoxycarbonyloxystyrene (TBS) and sulfur dioxide (SO2) have been found to act as sensitive x-ray ((lambda) equals 14 angstrom) and moderately sensitive electron-beam, single component, chemically amplified, aqueous base soluble positive acting resists. The x-ray and electron-beam response of these materials was a function of copolymer composition, where an increase in the sulfur dioxide content enhanced the resist sensitivity.

Anthony E. Novembre; Woon W. Tai; Janet M. Kometani; James E. Hanson; Omkaram Nalamasu; Gary N. Taylor; Elsa Reichmanis; Larry F. Thompson

1991-01-01

363

Charge Challenge  

NSDL National Science Digital Library

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.

Kansas, University O.

2006-01-01

364

Ultrafast disk lasers and amplifiers  

NASA Astrophysics Data System (ADS)

Disk lasers with multi-kW continuous wave (CW) output power are widely used in manufacturing, primarily for cutting and welding applications, notably in the automotive industry. The ytterbium disk technology combines high power (average and/or peak power), excellent beam quality, high efficiency, and high reliability with low investment and operating costs. Fundamental mode picosecond disk lasers are well established in micro machining at high throughput and perfect precision. Following the world's first market introduction of industrial grade 50 W picosecond lasers (TruMicro 5050) at the Photonics West 2008, the second generation of the TruMicro series 5000 now provides twice the average power (100 W at 1030 nm, or 60 W frequency doubled, green output) at a significantly reduced footprint. Mode-locked disk oscillators achieve by far the highest average power of any unamplified lasers, significantly exceeding the 100 W level in laboratory set-ups. With robust long resonators their multi-microjoule pulse energies begin to compete with typical ultrafast amplifiers. In addition, significant interest in disk technology has recently come from the extreme light laser community, aiming for ultra-high peak powers of petawatts and beyond.

Sutter, Dirk H.; Kleinbauer, Jochen; Bauer, Dominik; Wolf, Martin; Tan, Chuong; Gebs, Raphael; Budnicki, Aleksander; Wagenblast, Philipp; Weiler, Sascha

2012-02-01

365

Non-chemically amplified negative resist for EUV lithography  

NASA Astrophysics Data System (ADS)

Non-chemically amplified (CA) negative resist for EUV lithography was studied. Photo-induced thiol/ene radical reaction was used to insolubilize the resist based on poly(4-hydroxystyrene) (PHS) derivatives. Hydroxy groups of PHS were modified with allyl, norbornen, or methacrylate moiety. Dissolution property of the modified-PHS in TMAHaq solution was studied. The degree of the modification of PHS strongly affected the solubility in TMAHaq. Resist was a mixture of modified-PHS, multifunctional thiol compound, and photo-radical generator. Photo-sensitivity of the resist was studied at 254 nm and 13.5 nm. The sensitivity was affected the concentration of thiol compound added. It was found that the present resist system was highly sensitive (5~6 mJ/cm2) to EUV exposure.

Shirai, Masamitsu; Maki, Koichi; Okamura, Haruyuki; Kanayama, Koji; Itani, Toshiro

2009-03-01

366

A transimpedance CMOS multichannel amplifier with a 50 {Omega}-wide output range buffer for high counting rate applications  

SciTech Connect

A fast transimpedance multichannel amplifier has been designed, fabricated in CMOS 1.2-{micro}m technology and tested. Each channel consists of a current sensitive preamplifier followed by a voltage amplification stage and an on-chip buffer able to drive 50 {Omega} loads with an output range of {+-}800 mV. Measured peaking time at the output is 40 ns and the circuit recovers to baseline in 90 ns. This results in a counting capability of more than 10{sup 7} hits/s. Signals of both polarities can be handled. The first two stages consume a total of 2 mW per channel and the 50 {Omega} buffer consumes another 17 mW. The equivalent noise charge (ENC) is 1,100 e{sup {minus}} rms with a slope of 40e{sup {minus}}/pF. The IC is intended for use in gas and solid-state detectors with high particle rate and extensive charge release as in high energy calorimetry.

Haralabidis, N.; Loukas, D.; Misiakos, K.; Katsafouros, S. [N.C.S.R. Demokritos, Athens (Greece)

1997-01-01

367

Photon charge experiment  

NASA Astrophysics Data System (ADS)

The deflection of a laser beam traveling through a modulated electric field is measured using phase-sensitive detection to place an upper bound on the photon charge. An upper limit of 10-14e is obtained. Our approach provides a simple experimental scheme for angle measurements and is suitable as a laboratory exercise for both advanced undergraduate and beginning graduate students in physical science.

Hankins, A.; Rackson, C.; Kim, W. J.

2013-06-01

368

CMOS Optoelectronic Lock-In Amplifier With Integrated Phototransistor Array.  

PubMed

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

An Hu; Chodavarapu, Vamsy P

2010-10-01

369

A Low-Noise Semiconductor Optical Amplifier  

SciTech Connect

Optical amplifiers are essential devices for optical networks, optical systems, and computer communications. These amplifiers compensate for the inevitable optical loss in long-distance propagation (>50 km) or splitting (>10x). Fiber amplifiers such as the erbium-doped fiber amplifier have revolutionized the fiber-optics industry and are enjoying widespread use. Semiconductor optical amplifiers (SOAs) are an alternative technology that complements the fiber amplifiers in cost and performance. One obstacle to the widespread use of SOAs is the severity of the inevitable noise output resulting from amplified spontaneous emission (ASE). Spectral filtering is often used to reduce ASE noise, but this constrains the source spectrally, and improvement is typically limited to about 10 dB. The extra components also add cost and complexity to the final assembly. The goal of this project was to analyze, design, and take significant steps toward the realization of an innovative, low-noise SOA based on the concept of ''distributed spatial filtering'' (DSF). In DSF, we alternate active SOA segments with passive free-space diffraction regions. Since spontaneous emission radiates equally in all directions, the free-space region lengthens the amplifier for a given length of gain region, narrowing the solid angle into which the spontaneous emission is amplified [1,2]. Our innovation is to use spatial filtering in a differential manner across many segments, thereby enhancing the effect when wave-optical effects are included [3]. The structure quickly and effectively strips the ASE into the higher-order modes, quenching the ASE gain relative to the signal.

Ratowsky, R.P.; Dijaili, S.; Kallman, J.S.; Feit, M.D.; Walker, J.

1999-03-23

370

Quasi-optical antenna array amplifiers  

Microsoft Academic Search

Several quasi-optical transmission wave amplifiers are presented: (1) a two-level power-combining PHEMT patch-antenna lens amplifier with 8 dB of absolute power gain at 9.7 GHz used for beamforming and beam-switching; (2) a saturated class-A polarization-preserving 24-MESFET patch array which produces 0.7 Watts at 10 GHz with 21% power-added efficiency; and (3) an X-band 2-stage low-noise CPW PHEMT amplifier cell using

Jon Schoenberg; Tom Mader; Boyd Shaw; Z. B. Popovic

1995-01-01

371

Signal Conditioning Amplifier and Recorder (SCAmpR).  

National Technical Information Service (NTIS)

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...

P. J. Medelius

2002-01-01

372

Ultra-low-voltage floating-gate transconductance amplifiers  

Microsoft Academic Search

Ultra-low-voltage (ULV) floating-gate differential amplifiers are presented. In this paper, we present several different approaches to CMOS ULV amplifier design. Sinh-shaped and tanh-shaped transconductance amplifiers are described. Measured results are provided

YNGVAR BERG; TOR S. LANDE; O. Naess; Henning Gundersen

2001-01-01

373

Phased Array Antenna Amplifier Exploratory Development Model.  

National Technical Information Service (NTIS)

This final report describes the design characteristics and test results of a scale model (mechanically steerable) Phase Array Antenna Amplifier. As a result of this development investigation, a design approach for a 1 KW system is presented. This report i...

P. Muscianesi J. Irvine J. Ranghelli

1979-01-01

374

Fluidic Vortex Amplifier for Environmental Control.  

National Technical Information Service (NTIS)

The work focused on a technology that uses a fluidic vortex amplifier for environmental control of industrial enclosures. The basic requirement for environmental control is a flow component that can vary its flow resistance quickly and automatically in re...

S. C. Chang

1987-01-01

375

Undulators for short wavelength FEL amplifiers.  

National Technical Information Service (NTIS)

Issues critical to the design of undulators for use in short wavelength FEL amplifiers, such as attainable on-axis field strength, device compactness, field quality, required magnetic gap, and strong focusing schemes, are discussed. The relative strength ...

R. D. Schlueter

1994-01-01

376

Output Performance of Idealized Microwave Power Amplifiers.  

National Technical Information Service (NTIS)

Output power, efficiency, power dissipation and optimum load resistance expressions for idealized microwave class A and class B power amplifiers are derived based on a waveform analysis. The effects of device transconductance variation with bias and circu...

L. J. Kushner

1989-01-01

377

High Current, Very Wide Band Transconductance Amplifier.  

National Technical Information Service (NTIS)

The present invention relates to high current transconductance amplifiers that are stable over a very wide bandwidth. The invention overcomes current/frequency limitations by utilizing the inherent tendency for paralleled current mirrors to add currents s...

O. Laug

1989-01-01

378

One Kilowatt UHF Power Amplifier Study.  

National Technical Information Service (NTIS)

A study effort was conducted to determine the current state-of-the-art in one kilowatt UHF power amplifiers. Studies and investigations culminated in a final technical report containing a detail performance specification and recommended overall design app...

P. R. Hoffmann

1975-01-01

379

Integrated CMOS amplifier for ENG signal recording.  

PubMed

The development and in vivo test of a fully integrated differential CMOS amplifier, implemented with standard 0.7-microm CMOS technology (one poly, two metals, self aligned twin-well CMOS process) intended to record extracellular neural signals is described. In order to minimize the flicker noise generated by the CMOS circuitry, a chopper technique has been chosen. The fabricated amplifier has a gain of 74 dB, a bandwidth of 3 kHz, an input noise of 6.6 nV/(Hz)0.5, a power dissipation of 1.3 mW, and the active area is 2.7 mm2. An ac coupling has been used to adapt the electrode to the amplifier circuitry for the in vivo testing. Compound muscle action potentials, motor unit action potentials, and compound nerve action potentials have been recorded in acute experiments with rats, in order to validate the amplifier. PMID:15605867

Uranga, A; Navarro, X; Barniol, N

2004-12-01

380

High Frequency Low Noise Amplifier Project.  

National Technical Information Service (NTIS)

The design of low noise high frequency amplifiers using S parameters for transistors is described. Simple equations are given for the design of the matching circuits and for determining the minimum noise figure parameters.

W. J. Fleming

1981-01-01

381

High Bandwidth Differential Amplifier for Shock Experiments  

SciTech Connect

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.

Ross, P., Tran, V., Chau, R.

2012-10-01

382

High bandwidth differential amplifier for shock experiments.  

PubMed

We developed a high bandwidth differential amplifier for gas gun shock experiments of low-resistance metals. 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 ?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. PMID:23126892

Ross, P W; Tran, V; Chau, R

2012-10-01

383

Gigahertz low noise CMOS transimpedance amplifier  

Microsoft Academic Search

A new class of low noise CMOS common gate transimpedance amplifier is described. What is novel about the design is the total isolation of the photodiode capacitance from determining the -3 dB bandwidth. HSPICE simulations of this amplifier were conducted using the Tritech 0.6 ?m CMOS process. Simulated performance gives 2 GHz bandwidth, 1.13 k? transimpedance gain and very low

S. M. Park; C. Toumazou

1997-01-01

384

Recent progress in semiconductor laser amplifiers  

Microsoft Academic Search

Recent progress in semiconductor laser amplifiers (SLAs), mainly GaInAsP traveling-wave semiconductor laser amplifiers (TWAs) for use in optical fiber transmission systems, is discussed. The status of antireflection coating on laser-diode facets which are indispensable for TWAs is discussed. Reported data on small-signal gain, signal-gain saturation, and noise are summarized and discussed in relation to active-layer parameters. Common amplification using SLAs

Tadashi Saitoh; Takaaki Mukai

1988-01-01

385

Hybrid integrated lumped-element microwave amplifiers  

Microsoft Academic Search

This paper describes the development of microwave lumped-element thin-film amplifiers. The basic design philosophy underlying lumped inductors and capacitors at microwave frequencies is reviewed, showing how Q's of 100 are achieved. A variety of tunable input, output, and interstage integrated lumped-element networks for transistor amplifiers were fabricated. The gain and efficiency of 2-GHz class-C operated transistors mounted in these circuits

MARTIN CAULTON; STANLEY P. KNIGHT; DANIEL A. DALY

1968-01-01

386

A fast, thermally stable bipolar pulse amplifier  

Microsoft Academic Search

An alternative to the normal 'audio'-type pulse amplifier which provides high-power electrical pulses with fast rise and fall times is described. The amplifier uses saturated transistors without feedback. The basic concept is to provide separate drives to the complementary output transistors with a mechanism to ensure that there can be no common-mode current: that even with device delay times it

R. N. Caffin

1982-01-01

387

Amplifiers and Lasers in PCF Configurations  

Microsoft Academic Search

In this paper we will present an overview of the use \\u000aof photonic crystal fibers as fiber amplifiers. We \\u000awill describe the basic concepts of optical \\u000aamplification, and how to do numerical modelling of \\u000asuch components. We will then identify advantages \\u000aand disadvantages of amplifiers based on PCF\\u000atechnology compared to conventional fibers, and then \\u000ago into greater detail on

Kristian Hougaard; Frederik D. Nielsen

2004-01-01

388

Optical fibers and amplifiers for WDM systems  

Microsoft Academic Search

The development of optical-fiber amplifiers allowed a dramatic increase in the capacity of optical transmission systems while reducing system costs. Capacity increases are possible because the high output powers afforded by optical-fiber amplifiers support higher bit rates, while their broad bandwidth and slow gain dynamics allow multichannel operation. This benefit comes at the expense of having to manage signal-to-noise ratio

MICHAEL J. YADLOWSKY; EVELYN M. DELISO; V. L. Da Silva

1997-01-01

389

One kilowatt UHF solid state power amplifier  

Microsoft Academic Search

The One-Kilowatt UHF Solid State Amplifier System (AN\\/ASC-31) is a state of the art airborne amplifier containing a fast tuning filter. This system interfaced with an AN\\/ARC-171 and modem generates a 1KW clean signal capable of fast hopping across the 225-400 MHz UHF frequency band. This report contains a description of the system and test results. The various tests accomplished

W. Fischbach

1982-01-01

390

Integrated CMOS amplifier for ENG signal recording  

Microsoft Academic Search

The development and in vivo test of a fully integrated differential CMOS amplifier, implemented with standard 0.7-?m CMOS technology (one poly, two metals, self aligned twin-well CMOS process) intended to record extracellular neural signals is described. In order to minimize the flicker noise generated by the CMOS circuitry, a chopper technique has been chosen. The fabricated amplifier has a gain

A. Uranga; X. Navarro; N. Barniol

2004-01-01

391

A digitally programmable VGA [variable gain amplifier  

Microsoft Academic Search

This paper presents a digitally programmable MOST-only variable gain amplifier (VGA) built around a high-performance fully-differential operational amplifier with gain enhancement. Digital controllability is based on an inherent linear MOST-only current division technique. The system, built in 0.8 ?m CMOS technology and supplied at 3.3 V, achieves gains between -34 dB and 54 dB with linearity better than -80 dB

T. Sanz; B. Calvo; S. Celma; C. Moran

2001-01-01

392

Conceptual designs of a 50 nm FEL oscillator and a 20-40 nm SASE amplifier  

NASA Astrophysics Data System (ADS)

This paper consists of two parts; (1) the conceptual design, and optical performance characteristics, of a grazing angle of incidence ring resonator utilizing multifaceted metal mirrors for use with a 50 nm rf linac driven XUV FEL oscillator, and (2) electron beam and wiggler requirements for a self-amplified spontaneous emission (SASE) amplifier to produce high power in the 20-40 nm wavelength range. The basis for these studies is the 3-d FEL simulation code FELEX which, in part (1), is used to derive tolerances on mirror figure and thermal distortion, alignment sensitivity, and alternative output coupling methods. In part (2), the sensitivity of the output characteristics of an XUV FEL SASE amplifier to wiggler field errors is also studied.

Goldstein, John C.; McVey, Brian D.; Elliott, C. James

1988-10-01

393

Multiple excitation regenerative amplifier inertial confinement system  

DOEpatents

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.

George, Victor E. (Livermore, CA); Haas, Roger A. (Pleasanton, CA); Krupke, William F. (Pleasanton, CA); Schlitt, Leland G. (Livermore, CA)

1980-01-01

394

A high-power 95 GHz gyro-TWT amplifier  

NASA Astrophysics Data System (ADS)

The need for radar systems with greater resolution has led to renewed interest in the development of efficient high-power amplifiers at 95 GHz. The gyro-TWT is capable of producing high power with the added attraction of having lower ohmic loading on the smooth fast-wave interaction circuit than conventional slow-wave sources. We have completed a comprehensive design of a 95 GHz gyro-TWT amplifier that is capable of producing 120 kW of output power with an efficiency of 30 percent, a saturated gain of 38 dB, and an instantaneous bandwidth of over 5 GHz. Our concept uses an annular beam produced by a MIG electron source and operates in the TE(sub 5,1) cylindrical waveguide mode. Realistic beam parameters from gun simulations were, included in our efficiency calculations. In addition, our design includes the use of a compact superconducting magnet, quasi-optical input and output couplers and a sever to suppress oscillations. The overall mechanical design shows that a compact, lightweight amplifier with adequate beam clearance is possible. This report also includes a study of a gyro-TWT using a solid on-axis beam from a Pierce-wiggler electron source coupling with a TE(sub 1,eta) waveguide mode. Nonlinear models indicated that an efficient interaction with the waveguide mode was possible, however, beam simulations indicated that the high current density beam had large internal space charge forces that caused a substantial degradation of the beam quality.

Kreischer, K. E.; Basten, M.; Blank, M.; Danly, B. G.; Guss, W. C.; Temkin, R. J.

1992-07-01

395

Measurement of the amplified spontaneous emission loss in an iodine photodissociation laser amplifier  

SciTech Connect

The directional amplified spontaneous emission (ASE) along the laser tube of an iodine photodissociation laser (IPL) amplifier is measured and the experimental results are compared with the one-dimensional ASE theory. Also, we have measured the loss of the stored energy in the IPL amplifier due to the omnidirectional ASE. The loss is found to be 13.5% for the present amplifier when the laser medium i-C/sub 3/F/sub 7/I is 72 Torr and no argon buffer gas is added. But by adding the argon buffer gas to 210 Torr, it is reduced to 4.2%.

Hahn, J.W.; Lee, S.S.

1985-11-15

396

Simulation of magnetrons and crossed-field amplifiers  

NASA Astrophysics Data System (ADS)

A computer program for simulation of the magnetron oscillator and crossed-field amplifiers is described. Emphasis is placed on accuracy and efficient computation with moderate numbers of electrons and moderately large time steps. Distinctive features are: (1) space-charge field evaluation by Buneman's (1969) cycle reduction method and separate treatment of electrons near the cathode; (2) circuit field and electronic induction calculation by use of a Ramo (Green's) function, accounting for space harmonics; (3) calculation of RF network response by means of Green's functions; (4) predictor/corrector evaluation of average RF signals; and (5) use of fifth-degree power series calculation of electron trajectories. The simulation is illustrated in the starting of oscillations from computer noise.

Dombrowski, George E.

1988-11-01

397

Low-FPN high-gain capacitive transimpedance amplifier for low-noise CMOS image sensors  

Microsoft Academic Search

In this paper we introduce a low fixed pattern noise (LFPN) capacitive transimpedance amplifier (CTIA) for active pixel CMOS image sensors (APS) with high switchable gain and low read noise. The LFPN CTIA APS uses a switched capacitor voltage divider feedback circuit to achieve high sensitivity, low gain FPN, and low read noise. This paper discusses the operation of the

Boyd A. Fowler; Janusz Balicki; Dana How; Michael Godfrey

2001-01-01

398

Sequence characterized amplified region markers: A reliable tool for adulterant detection in turmeric powder  

Microsoft Academic Search

Turmeric powder (Curcuma longa L.), an important medicinal spice product traded internationally, is subjected to adulteration by design or default with powders of related curcumin containing wild species like Curcuma zedoaria and Curcuma malabarica leading to toxicity and poor quality of the produce. The present study aims at development of specific, sensitive and reproducible Sequence Characterized Amplified Region (SCAR) markers

K. Dhanya; S. Syamkumar; S. Siju; B. Sasikumar

2011-01-01

399

Process Optimization for Monolithic Integration of Piezoresistive Pressure Sensor and MOSFET Amplifier with SOI Approach  

NASA Astrophysics Data System (ADS)

In this paper we present the design and process optimization for fabricating piezoresitive pressure sensor and MOSFET Differential Amplifier simultaneously on the same chip. Silicon On Insulator approach has been used for realizing the membrane as well as the electronics on the same chip. The amplifier circuit has been configured in the common source connection and it has been designed with PSPICE simulation to achieve a voltage gain of about 5. In the initial set of experiments the Pressure sensor and the amplifier were fabricated on separate chips to optimize the process steps and tested in the hybrid mode. In the next set of experiments, SOI wafer having the SOI layer thickness of about 11 microns was used for realizing the membrane by anisotropic etching from the backside. The piezo-resistive pressure sensor was realized on this membrane by connecting the polysilicon resistors in the form of a Wheatstone bridge. The MOSFET source follower amplifier was also fabricated on the same SOI wafer by tailoring the process steps to suit the requirement of simultaneous fabrication of piezoresistors and the amplifier for achieving MOSFET Integrated Pressure Sensor. Reproducible results have been achieved on the SOI wafers, with the process steps developed in the laboratory. Sensitivity of 270 mV /Bar/10V, with the on chip amplifier gain of 4.5, has been achieved with this process.

Vinoth Kumar, V.; Dasgupta, A.; Bhat, K. N.; KNatarajan

2006-04-01

400

Light-Enhanced Charge Mobility in a Molecular Hole Transporter  

Microsoft Academic Search

We present an investigation into the charge transport through a molecular hole transporter. Under illumination, photoinduced charge transfer occurs from a sensitizer to the hole transporter. The increased hole density results in striking enhancements in film conductivity, up to 106, and charge carrier mobility, up to 103. Such enhancements in mobility at low charge densities have not previously been observed

Henry J. Snaith; Michael Grätzel

2007-01-01

401

Up-converted 1/f PM and AM noise in linear HBT amplifiers.  

PubMed

In this paper we describe a technique to predict the 1/f phase modulation (PM) and 1/f amplitude modulation (AM) noise due to up-conversion of 1/f baseband current noise in microwave heterojunction bipolar transistor (HBT) amplifiers. We obtain an accurate model for the amplifier and find the expression for voltage gain in terms of DC bias, transistor parameters, and circuit components. Theoretical 1/f PM and AM noise sensitivities to 1/f baseband current noise are then found by applying the definitions of PM and AM noise to the gain expression of the amplifier. Measurements of PM and AM sensitivities at 500 MHz and 1 GHz were in good agreement with the values predicted by theory, verifying the validity of this technique. This method can be used to optimize amplifier design for low PM and AM noise. We show that the amplifier PM noise can be reduced by 9 dB by adjusting the value of the input coupling capacitor. PMID:18986914

Ferre-Pikal, Eva S; Savage, Frederick H

2008-08-01

402

Design of wide-bandwidth envelope-tracking power amplifiers for OFDM applications  

Microsoft Academic Search

An efficiency-enhanced power-amplifier system design is presented based on wide-bandwidth envelope tracking (WBET) with application to orthogonal frequency-division multiplexing wireless local area network systems. Envelope elimination and restoration (EER) and WBET are compared in terms of the time mismatch sensitivity between the base-band amplitude path and the RF path, and it is demonstrated that WBET is much less sensitive than

Feipeng Wang; Annie Hueiching Yang; Donald F. Kimball; Lawrence E. Larson; Peter M. Asbeck

2005-01-01

403

Low noise multichannel amplifier for portable EEG biomedical applications  

Microsoft Academic Search

An low noise EEG biopotential multichannel amplifier is presented. The amplifier is designed by use of integrated circuits such as the instrumentation amplifier AD620, very low offset voltage OP77, switched capacitor low pass filter Max 281, etc. The amplifier is applied in multichannel medical equipment together with a microprocessor and PCMCIA memory, in a portable battery operated system. The portable

L. Badillo; V. Ponomaryov; E. Ramos; L. Igartua

2003-01-01

404

Generalized noise analysis of spatially inhomogeneous laser amplifiers  

Microsoft Academic Search

A classical approach for treating the noise properties of spatially inhomogeneous laser amplifiers is presented. Based on the Green's function method, the amplifier output is related to the input and the amplified spontaneous emission noise. By using the correlation properties of spatially distributed spontaneous emission, the amplifier noise variance is obtained in a rigorous way. Compared with the density operator

Guang-Hua Duan

1993-01-01

405

Gain analysis of Erbium and Ytterbium Doped Optical Fiber Amplifiers  

Microsoft Academic Search

In this study, importance of optical amplifiers which are used in optical communication systems is explained and gains of EDFA, Erbium Doped Fiber Amplifier, and YDFA, Ytterbium Doped Fiber Amplifier, which are among the most commonly used optical amplifiers today, are analysed based on their performance parameters. The effects of the power of input signal, the power of pump laser,

Tolga Kucukarslan; N. Ozlem Unverdi

2012-01-01

406

New High Power Test Facility for VHF Power Amplifiers at LANSCE  

Microsoft Academic Search

A new test facility was designed and constructed at Los Alamos Neutron Science Center (LANSCE) for testing the Thales TH628 Diacrode{sup R} and TH781 tetrode power amplifiers. Anode power requirements for the TH628 are 28 kV DC, with peak currents of 190 Amperes in long pulses. A charging power supply was obtained by reconfiguring a 2 MW beam power supply

John T. Lyles; Steve Archuletta; David M. Baca; Ray E. Bratton; Nicholas W. Brennan; Jerry L. Davis; Luis J. Lopez; Daniel E. Rees; Manuelita B. Rodriguez; Gilbert M. Jr. Sandoval; Andy I. Steck; Richard D. Summers; Danny J. Vigil

2011-01-01

407

The role of amplifiers in sexual selection: An integration of the amplifying and the Fisherian mechanisms  

Microsoft Academic Search

Summary  In a non-Fisherian genetic model I have shown that sexual displays can evolve even if displays are not directly and unconditionally preferred by females (a basic requirement in any Fisherian model), provided that they amplify previously recognized differences in male quality. Here I show how this amplifying mechanism interacts with the traditional Fisherian mechanism of sexual selection. The theory that

Oren Hasson

1990-01-01

408

Clinical Evaluation of the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test for Rapid Diagnosis of Tuberculosis Lymphadenitis  

PubMed Central

This prospective study evaluated the performance of the Amplified Mycobacterium Tuberculosis Direct Test (MTD) for the diagnosis of lymph node tuberculosis in Djibouti, Republic of Djibouti. Of 197 specimens sampled from 153 patients, 123 were from 95 tuberculous patients. The sensitivity and specificity of MTD were 93 and 100%, respectively. The sensitivity of culture was 89%.

Kerleguer, A.; Fabre, M.; Bernatas, J. J.; Gerome, P.; Nicand, E.; Herve, V.; Koeck, J. L.

2004-01-01

409

Non-chemically amplified 248-nm resist materials  

NASA Astrophysics Data System (ADS)

Remarkable progress has been made in the formulation of chemically amplified resists for deep-UV (DUV or 248 nm) lithography. These materials are now in general use in full scale manufacturing. One of the deterrents to rapid and universal adoption of DUV lithography has been the combination of high cost of ownership and a narrow process latitude when compared to conventional i-line process alternatives. A significant part of the high cost of the DUV process is associated with installing and maintaining special air handling equipment that is required to remove basic contaminants from the ambient. Manufacture process latitude demands this special air handling. The chemically amplified resists were developed originally to support mercury lamp powered exposure systems. The sensitivity realized by chemical amplification is required to enable useful productivity with such systems that generate very little DUV flux at the wafer plane. With the advent of high powered excimer laser based illumination systems for 248 nm steppers and step-and-scan systems, it is appropriate to re-examine the applicability of non-chemically amplified DUV resist systems. These systems are less sensitive but have the potential to offer both lower cost of ownership and improved process latitude. A series of photoactive compounds (PACs) have been synthesized and auditioned for use in the formulation of a non-chemically amplified 248 nm resist. The most promising of these materials are analogs of 3-oxo-3-diazocoumarin. This chromophore displays photochemistry that is analogous to that of the diazonaphthoquinones (DNQ) that are the basis of i-line resist formulations, but it bleaches at 248 nm. Several structural analogs of the chromophore have been synthesized and a variety of ballast groups have been studied with the goal of enhancing the dissolution inhibition properties of the molecule. The diazocoumarin PACs have been formulated with customized phenolic resins that were designed to provide the combination of optical transparency, dry etch resistance and the dissolution characteristics that are required for manufacturing applications. The resins are copolymers of poly(4-hydroxystyrene) and blends of these polymers with novolac.

Willson, C. Grant; Yueh, Wang; Leeson, Michael J.; Steinhausler, Thomas; McAdams, Christopher L.; Dammel, Ralph R.; Sounik, James R.; Aslam, M.; Vicari, Richard; Sheehan, Michael

1997-07-01

410

Dual mode 1.25-2.5 Gb/s CMOS limiting amplifier circuit for optical receivers  

NASA Astrophysics Data System (ADS)

A 1.25-2.5Gb/s burst-mode limiting amplifier for gigabit passive optical networks (GPON) is presented in this paper. It supports both PIN-PD and APD diodes. A response time of 5 ns and sensitivity of 4 mVpp is achieved by introducing a modified amplified stage with active feedback and negative Miller capacitance compensation techniques. This circuit operates with a supply voltage 3 V and it is fabricated in 180 nm CMOS technology. The influence of the parasitic layout elements and their effects on the performance of the limiting amplifier will be illustrated using RC and RLC parasitic extraction and simulation results.

Albina, Cristian M.

2009-01-01

411

Transceiver battery charging apparatus and method  

SciTech Connect

A battery charger is described for a hand-held transceiver having a rechargeable battery, comprising: a housing having means for receiving the transceiver; connector means for electrically connecting the battery charger to the transceiver, the connector means including a microphone terminal, an RF terminal, a mode control terminal and a charger output terminal; a microphone unit having a microphone and a mode switch, the microphone being electrically coupled to the microphone terminal; multiwire cable means for attaching the microphone unit to the housing; an RF amplifier having an input and an output; an antenna lead connected to the RF amplifier output; mode control means for correspondingly controlling the operating modes of the battery charger and the transceiver for transmit and receive modes, the mode control means having an input connected to the mode switch and an output connected to the mode control terminal; means responsive to the mode control means for coupling the RF terminal to the RF amplifier input during transmit mode and to the antenna lead during receive mode; and charging circuit means for selectively charging the transceiver battery from a source of a first voltage during transmit mode and from a source of a second, higher voltage during receive mode. The charging circuit means has an output connected to the charger output terminal.

George, D.L.; Benson, R.G. Jr.

1987-08-04

412

Graphene-based charge sensors  

NASA Astrophysics Data System (ADS)

We discuss graphene nanoribbon-based charge sensors and focus on their functionality in the presence of external magnetic fields and high frequency pulses applied to a nearby gate electrode. The charge detectors work well with in-plane magnetic fields of up to 7 T and pulse frequencies of up to 20 MHz. By analyzing the step height in the charge detector’s current at individual charging events in a nearby quantum dot, we determine the ideal operation conditions with respect to the applied charge detector bias. Average charge sensitivities of 1.3 × 10?3e Hz?1/2 can be achieved. Additionally, we investigate the back action of the charge detector current on the quantum transport through a nearby quantum dot. By varying the charge detector bias from 0 to 4.5 mV, we can increase the Coulomb peak currents measured at the quantum dot by a factor of around 400. Furthermore, we can completely lift the Coulomb blockade in the quantum dot.

Neumann, C.; Volk, C.; Engels, S.; Stampfer, C.

2013-11-01

413

Graphene-based charge sensors.  

PubMed

We discuss graphene nanoribbon-based charge sensors and focus on their functionality in the presence of external magnetic fields and high frequency pulses applied to a nearby gate electrode. The charge detectors work well with in-plane magnetic fields of up to 7 T and pulse frequencies of up to 20 MHz. By analyzing the step height in the charge detector's current at individual charging events in a nearby quantum dot, we determine the ideal operation conditions with respect to the applied charge detector bias. Average charge sensitivities of 1.3 × 10(-3)e Hz(-1/2) can be achieved. Additionally, we investigate the back action of the charge detector current on the quantum transport through a nearby quantum dot. By varying the charge detector bias from 0 to 4.5 mV, we can increase the Coulomb peak currents measured at the quantum dot by a factor of around 400. Furthermore, we can completely lift the Coulomb blockade in the quantum dot. PMID:24113720

Neumann, C; Volk, C; Engels, S; Stampfer, C

2013-10-10

414

Coupled experiment\\/simulation approach for the design of radiation-hardened rare-earth doped optical fibers and amplifiers  

Microsoft Academic Search

We developed an approach to design radiation-hardened rare earth -doped fibers and amplifiers. This methodology combines testing experiments on these devices with particle swarm optimization (PSO) calculations. The composition of Er\\/Yb-doped phosphosilicate fibers was improved by introducing Cerium inside their cores. Such composition strongly reduces the amplifier radiation sensitivity, limiting its degradation: we observed a gain decreasing from 19 dB

S. Girard; L. Mescia; M. Vivona; A. Laurent; Y. Ouerdane; C. Marcandella; F. Prudenzano; A. Boukenter; T. Robin; P. Paillet; V. Goiffon; B. Cadier; M. Cannas; R. Boscaino

2011-01-01

415

Ultra-broadband amplified spontaneous emission source by using heterogeneous optical amplifier  

NASA Astrophysics Data System (ADS)

In this work, we propose and experimentally investigate an ultra-broadband amplified spontaneous emission (ASE) light source with 113.8 nm bandwidth (1446.2 to 1560.0 nm) by using a cascaded two-stage optical amplifier, which is consisted of semiconductor optical amplifier (SOA, 1st stage) and erbiumdoped fiber amplifier (EDFA, 2nd stage), when the output intensity is above -35 dBm/0.01 nm. And, the EDFA only uses a 3 m long erbium-doped fiber (EDF) with a 27 mW pumping power and SOA is driven at 200 mA bias current. Moreover, the proposed amplifier also can provide a broadband gain amplification of 114 nm in the wavelengths of 1464.0 and 1578.0 nm with the noise figure distribution of 6.8 to 8.1 dB.

Yeh, C. H.; Chow, C. W.; Chen, J. H.; Lu, S. S.

2012-11-01

416

Series-Tuned Amplifier, a Low Noise Preamplifier  

Microsoft Academic Search

Parallel-tuned circuits are commonly used in transistor bandpass amplifiers, e.g., IF amplifiers. However, series-tuned circuits have some important advantages. This correspondence presents a simple noise analysis for a parallel-tuned and a series-tuned amplifier. The transfer functions of both amplifiers are similar, but the series-tuned amplifier gives a smaller noise figure. Hence, series-tuned circuits are especially advantageous in preamplifiers.

O. Suominen

1967-01-01

417

Generalised analysis of gain-bandwidth independence in feedback amplifiers  

Microsoft Academic Search

Two closely related dominant-pole-compensated feedback amplifier configurations have recently been developed specifically to exploit gain-bandwidth independence and offer constant- bandwidth operation throughout the full gain range. Do these two new amplifier types - the current- feedback amplifier (CFA) and the transconductance-feedback amplifier (TFA) - actually operate in a fundamentally different way to previous feedback amplifiers? Or are they able to

B. Wilson

418

High Bandwidth Differential Amplifier for Shock Experiments  

SciTech Connect

We developed a high bandwidth differential amplifier for gas gun shock experiments/applications. The circuit has a bandwidth > 1 GHz, and is capable of measuring signals of ?1.5 V with a common mode rejection of 250 V. Conductivity measurements of gas gun targets are measured by flowing high currents through the targets. The voltage is measured across the target using a technique similar to a four-point probe. Because of the design of the current source and load, the target voltage is approximately 250 V relative to ground. Since the expected voltage change in the target is < 1 V, the differential amplifier must have a large common mode rejection. High pass filters suppress internal ringing of operational amplifiers. Results of bench tests are shown.

Ross, P. W., Tran, V., Chau, R.

2012-04-30

419

Power amplifier module with stable idling current  

US Patent & Trademark Office Database

A power amplifier module includes a bias circuit to produce an idling current and a power amplifier of which the gain is controlled by the idling current produced by the bias circuit. Effects of changes of control voltage and ambient temperature of the power amplifier module can be removed by a first detector in the bias circuit to detect changes of the control voltage and a second detector in the bias circuit to detect changes of the ambient temperature. The bias circuit may further include a differential circuit to make error amplification with the first detector provided to perform as a standard voltage source for ambient temperature detection of the second detector and the second detector provided to perform as a standard voltage source for control-voltage detection of the first detector. Thus, they serve as detection circuits or standard voltage sources mutually.

Yamashita; Kiichi (Shiroyama, JP)

2004-05-04

420

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

NASA Astrophysics Data System (ADS)

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.

Schier, Sheena; Schumm, Bruce

2012-03-01

421

Optical modulation of amplified emission in a polyfluorene-diarylethene blend.  

PubMed

A novel system for the modulation of amplified emission based on a polyfluorene/diarylethene (namely F8BT/DTP) blend is shown. The high sensitivity of amplified spontaneous emission (ASE) is exploited to achieve efficient emission modulation with a low-intensity control signal. Modulation is then characterized by photoluminescence (PL) lifetime measurements, photocurrent experiments, and density functional theory calculations. This system can also act as a photocurrent switch based on the same principle. This technique may represent a useful tool for fluorescence quenching and sensing as well as find application in organic photonics. PMID:22025448

Perissinotto, Stefano; Garbugli, Michele; Fazzi, Daniele; Bertarelli, Chiara; Carvelli, Marco; Kandada, Ajay R Srimath; Yue, Zhounan; Wong, Kam S; Lanzani, Guglielmo

2011-10-24

422

Get Charged!  

NSDL National Science Digital Library

Students are introduced to the idea of electrical energy. They learn about the relationships between charge, voltage, current and resistance. They discover that electrical energy is the form of energy that powers most of their household appliances and toys. In the associated activities, students learn how a circuit works and test materials to see if they conduct electricity. Building upon a general understanding of electrical energy, they design their own potato power experiment. In two literacy activities, students learn about the electrical power grid and blackouts.

Integrated Teaching And Learning Program

423

A high sensitivity ultralow temperature RF conductance and noise measurement setup  

SciTech Connect

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.

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

424

Cryogenic transimpedance amplifier for micromechanical capacitive sensors.  

PubMed

We developed a cryogenic transimpedance amplifier that works at a broad range of temperatures, from room temperature down to 4 K. The device was realized with a standard complementary metal oxide semiconductor 1.5 mum process. Measurements of current-voltage characteristics, open-loop gain, input referred noise current, and power consumption are presented as a function of temperature. The transimpedance amplifier has been successfully applied to sense the motion of a polysilicon micromechanical oscillator at low temperatures. The whole device is intended to serve as a magnetometer for microscopic superconducting samples. PMID:19044372

Antonio, D; Pastoriza, H; Julián, P; Mandolesi, P

2008-08-01

425

Cryogenic transimpedance amplifier for micromechanical capacitive sensors  

NASA Astrophysics Data System (ADS)

We developed a cryogenic transimpedance amplifier that works at a broad range of temperatures, from room temperature down to 4 K. The device was realized with a standard complementary metal oxide semiconductor 1.5 ?m process. Measurements of current-voltage characteristics, open-loop gain, input referred noise current, and power consumption are presented as a function of temperature. The transimpedance amplifier has been successfully applied to sense the motion of a polysilicon micromechanical oscillator at low temperatures. The whole device is intended to serve as a magnetometer for microscopic superconducting samples.

Antonio, D.; Pastoriza, H.; Julián, P.; Mandolesi, P.

2008-08-01

426

Directly diode-pumped Colquiriite regenerative amplifiers  

NASA Astrophysics Data System (ADS)

The Colquiriite crystals are attractive materials for directly diode-pumped femtosecond oscillators and amplifiers. Cr:LiSAF, Cr:LiSGAF and Cr:LiCAF are for the first time directly compared for their use in regenerative amplifiers both experimentally and theoretically. A maximum pulse energy of 10 ?J was obtained at an absorbed pump power of 1.1 W. A review of the work is given including a Cr:LiSAF seed oscillator, outlining specific needs for seeding.

Isemann, A.; Weßels, P.; Fallnich, C.

2006-04-01

427

A millimeter-wave monolithic grid amplifier  

SciTech Connect

A 36-element monolithic grid amplifier has been fabricated. The peak gain is 5 dB at 40.8 GHz with a 3-dB bandwidth of 1.4 GHz. The active elements are pairs of heterojunction-bipolar-transistor`s(HBT`s). The individual transistors in the grid have a maximum oscillation frequency, f{sub max}, of 100 GHz. The grid includes base stabilizing capacitors which result in a highly stable grid. This is the first report of a successful monolithic grid amplifier.

Liu, C.M.; Rutledge, D.B. [California Institute of Technology, Pasadena, CA (United States); Sovero, E.A. [Rockwell International Corporation, Thousand Oaks, CA (United States)] [and others

1995-11-01

428

X-Band Peeled HEMT Amplifier.  

National Technical Information Service (NTIS)

A discrete peeled high electron mobility transistor (HEMT) device was integrated into a 10 GHz amplifier. The discrete HEMT device interconnects were made using photo patterned metal, stepping from the 10 mil alumina host substrate onto the 1.3 microns th...

P. G. Young R. R. Romanofsky S. A. Alterovitz E. D. Smith

1993-01-01

429

Generalized Solutions for Optical Maser Amplifiers  

Microsoft Academic Search

The optical maser amplifier is treated from the transient analysis point of view using the Laplace transform method as opposed to the conventional sinusoidal steady-state analysis that sometimes leads to inconsistent results especially for the region beyond threshold. Firstly, the wave equations are expressed in terms of laplace transforms, and then the generalized solutions for both the transmission and the

N. Kumagai; H. Yamamoto

1965-01-01

430

The decibel relationships between amplifier distortion products  

Microsoft Academic Search

Assuming that the transfer characteristic of the amplifier can be represented by a power series with three terms, an analysis is carried out to determine the frequency and amplitude of each distortion component. To make it easy to apply these results to a practical situation, the necessary constants are defined to enable expressing these relationships in decibel terms. The results

K. A. Simons

1970-01-01

431

Advances in ceramic packaging for power amplifiers  

Microsoft Academic Search

Power Amplifiers (PAs) for the past few years have been going through a drastic evolution in terms of packaging size and materials. Recent trends have seen the conversion from plastic molding packaging concepts of sizes from .5 to 1.0 CC to functional ceramic substrates incorporating matching circuits miniaturized to sizes of less than .02 CCs. In this paper PA packaging

R. E. Sigliano; F. J. Gaughan

1998-01-01

432

Digitally programmable transconductance amplifier for CNN applications  

Microsoft Academic Search

A major problem in the VLSI implementation of cellular neural networks (CNNs) is that of achieving ease of programmability of the templates. The authors present a very efficient VLSI implementation of a digitally programmable transconductance amplifier for cellular neural network applications with discrete templates.

F. Sargeni

1994-01-01

433

Aspheric Cassegrain Laser Power Amplifier System.  

National Technical Information Service (NTIS)

This patent application is directed to a power amplifier system which extracts high power optical radiation from a laser media. The system includes a gas dynamic, E-beam, or chemical laser from which power is extracted. The extracted power is as near diff...

R. R. Fluhr S. T. Hanley R. B. Brown

1975-01-01

434

High efficiency monolithic gallium nitride distributed amplifier  

Microsoft Academic Search

The first gallium-nitride monolithic distributed amplifier is demonstrated. A nonuniform design allows the removal of the drain line dummy load with a concomitant increase in efficiency, An optimized nonuniform design shows a 10% increase in efficiency over an optimized uniform design having the dummy termination

Bruce M. Green; Sungjae Lee; Kenneth Chu; Kevin J. Webb; Lester F. Eastman

2000-01-01

435

Full Wave Modulator-Demodulator Amplifier Apparatus.  

National Technical Information Service (NTIS)

A full-wave modulator-demodulator apparatus is described including an operational amplifier having a first input terminal coupled to a circuit input terminal, and a second input terminal alternately coupled to the circuit input terminal. A circuit is grou...

J. M. Black

1974-01-01

436

Biopotential amplifier for potential gradient measurements  

Microsoft Academic Search

This work proposes a bio-potential amplifier suitable for measurements from an electric potential gradient sensor, in electro-encephalography (EEG). The sensor is an array made by three electrodes placed on the vertices of an equilateral triangle of reduced size. Measuring the gradient requires small separation between electrodes hence, very low amplitude signals, of a few ?V, are obtained. Therefore, it is

Enrique M Spinelli; Carlos H Muravchik

2007-01-01

437

Touching the Heart: Books That Amplify Life.  

ERIC Educational Resources Information Center

Describes 31 children's books that connect with children and illustrate the significance that books that amplify life can hold for young and old alike. Discusses books with language and illustrations that are compelling, and how stories and images work together. Describes how teachers and college students chose books and artwork to help themselves…

Gilles, Carol; Pfannenstiel, Gennie

2000-01-01

438

Optimization of Pr3+-Doped Fiber Amplifiers.  

National Technical Information Service (NTIS)

Pr3+-doped fluorozirconate fiber amplifiers have been demonstrated to provide net-gains higher than 25 dB in a broad band centered on the 1300-nm communication window 1,2. We have developed a quantitative numerical model and systematically analysed the pe...

B. Pedersen W. J. Miniscalco R. S. Quimby

1992-01-01

439

Optimized flashlamp pumping of disc amplifiers  

SciTech Connect

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.

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

1986-01-17

440

A wideband RF amplifier for satellite tuners  

NASA Astrophysics Data System (ADS)

This paper presents the design and measured performance of a wideband amplifier for a direct conversion satellite tuner. It is composed of a wideband low noise amplifier (LNA) and a two-stage RF variable gain amplifier (VGA) with linear gain in dB and temperature compensation schemes. To meet the system linearity requirement, an improved distortion compensation technique and a bypass mode are applied on the LNA to deal with the large input signal. Wideband matching is achieved by resistive feedback and an off-chip LC-ladder matching network. A large gain control range (over 80 dB) is achieved by the VGA with process voltage and temperature compensation and dB linearization. In total, the amplifier consumes up to 26 mA current from a 3.3 V power supply. It is fabricated in a 0.35-?m SiGe BiCMOS technology and occupies a silicon area of 0.25 mm2.

Xueqing, Hu; Zheng, Gong; Yin, Shi; Foster, Dai Fa

2011-11-01

441

An Integratable Chaotic Oscillator with Current Amplifiers  

Microsoft Academic Search

A current-mode chaotic oscillator based on current amplifiers is studied. The oscillator operates on high frequencies and is suitable for on chip implementation. Its chaotic behavior is controlled by means of a bias voltage. Various methods for detecting chaos, such as the Lyapunov exponents, the Lyapunov dimension, the spectrum and the phase portraits are used, in order to confirm the

Konstantine Giannakopoulos; G. Souliotis; N. Fragoulis

2007-01-01

442

Gain characteristics of erbium doped fiber amplifier  

Microsoft Academic Search

In the design of Erbium Doped Fiber Amplifier (EDFA), improving flat-gain has great important significance. The working principle and gain characteristics of EDFA are introduced briefly, the influence of the factors such as Erbium doped fiber (EDF) length and pump power on the gain of EDFA is analyzed in detail, and the simulation experiments were carried out with Optisystem software.

Lihua Zhang; Yungang Du; Ying Xi; Jijun Li; Chunwang Zhao

2008-01-01

443

Design of powerful broadband transistorized amplifiers  

Microsoft Academic Search

The circumscribed mathematical model allows to design powerful broadband transistorized amplifiers (PBTA) by criterion of a minimum of technological losses of manufacture K6, and in case of using operating of monitoring cascades allows to allocate the most significant casual parameters of elements which, for example, can be chosen as, set up with the indicating, margins (borders) of their variations

A. V. Kolotvin; A. V. Pisanko; V. V. Maneev

2001-01-01

444

NON-BLOCKING STABILIZED FEED BACK AMPLIFIER  

DOEpatents

A plural stuge nonblocking degenerative feed-back amplifier was designed particularly suitable for counting circuits because of the stability and linearity in operation, characterized by the fact that the inltial stage employs a cathode coupled input circuit fed from a cathode follower and the final stage has a tline constant greater than those of the other stages.

Fairstein, E.

1960-03-01

445

Optical amplifier-powered quantum optical amplification  

SciTech Connect

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.

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

446

A Negative Feedback Amplifier and Level Shifter.  

National Technical Information Service (NTIS)

The patent application relates to a direct coupled linear amplifier which employs negative feedback to provide accurate and stable gain to AC as well as DC input signals. It also performs the function of a DC level shifter and can therefore be interfaced ...

S. J. Senger

1976-01-01

447

Time-gated imaging through dense scatters with a Raman amplifier  

NASA Astrophysics Data System (ADS)

The authors use a time-gated Raman amplifier to detect a bar chart hidden by a strongly scattering material. The time gating is provided by a frequency-doubled Nd:YAG pump laser having a pulse duration of 30 ps. The authors amplify and detect images with resolved structures smaller than 125 micron through suspensions of polystyrene spheres and nondairy creamer for light extinction factors of up to e(sup 33). Results of this study show that the Raman amplifier system can produce images under conditions in which the scattering medium was sufficiently dense that an image could not be detected on either a streak camera or by integration on a sensitive, low-noise camera.

Reintjes, J.; Tankersley, L. L.; Duncan, M. D.; Mahon, R.

1993-12-01

448

Micropulse slippage and optical mode distortion in the Boeing APLE amplifier  

NASA Astrophysics Data System (ADS)

In the Boeing Average Power Laser Experiment (APLE), the free electron laser (FEL) oscillator produces short optical pulses for input to the amplifier section. Micropulse slippage can become significant in the amplifier, competing with the effects of high gain and optical mode distortion. A two-dimensional simulation is used to study pulse slippage, and a three-dimensional simulation is used to study mode distortion. A four-dimensional simulation is used to simultaneously study these effects, and to look at the sensitivity of the efficiency to changes in various FEL parameters. We find that high gain and mode distortion effects dominate the pulse slippage effects. The amplifier is fairly insensitice to beam quality degradation and changes in the initial optical field, but a significant improvement in efficiency could be achieved by shortening the electron pulse.

Blau, J.; Frost, D. J.; Colson, W. B.

1993-07-01

449

Charge-collection mechanisms of heterostructure FETs  

Microsoft Academic Search

Ion- and laser-induced charge-collection transients measured for AlGaAs-InGaAs hetero-insulated-gate field-effect transistors (HIGFETs) reveal evidence for two mechanisms of enhanced charge collection: a channel-modulation mechanism that dominates the charge-collection processes at positive gate biases and can persist for several nanoseconds; and a parasitic bipolar transistor mechanism that shows a sensitive dependence on the density of free carriers injected into the device,

Dale McMorrow; Joseph S. Melinger; Napoleon Thantu; Arthur B. Campbell; Todd R. Weatherford; Alvin R. Knudson; Lan Hu Tran; Andrezej Peczalski

1994-01-01

450

Is there a role for amplifiers in sexual selection?  

PubMed

The amplifier hypothesis states that selection could favour the evolution of traits in signallers that improve the ability of receivers to extract honest information from other signals or cues. We provide a formal definition of amplifiers based on the receiver's mechanisms of signal perception and we present a game-theoretical model in which males advertise their quality and females use sequential-sampling tactics to choose among prospective mates. The main effect of an amplifier on the female mating strategy is to increase her mating threshold, making the female more selective as the effectiveness of the amplifier increases. The effects of the amplifier on male advertising strategy depends both on the context and on the types of the amplifier involved. We consider two different contexts for the evolution of amplifiers (when the effect of amplifiers is on signals and when it is on cues) and two types of amplifiers (the 'neutral amplifier', when it improves quality assessment without altering male attractiveness, and the 'attractive amplifier', when it improves both quality assessment and male attractiveness). The game-theoretical model provides two main results. First, neutral and attractive amplifiers represent, respectively, a conditional and an unconditional signalling strategy. In fact, at the equilibrium, neutral amplifiers are displayed only by males whose advertising level lays above the female acceptance threshold, whereas attractive amplifiers are displayed by all signalling males, independent of their quality. Second, amplifiers of signals increase the differences in advertising levels between amplifying and not-amplifying males, but they decrease the differences within each group, so that the system converges towards an 'all-or-nothing' signalling strategy. By applying concepts from information theory, we show that the increase in information transfer at the perception level due to the amplifier of signals is contrasted by a decrease in information transfer at the emitter level due to the increased stereotypy of male advertising strategy. PMID:18371984

Gualla, Filippo; Cermelli, Paolo; Castellano, Sergio

2008-03-10

451

Resonant charging  

NASA Astrophysics Data System (ADS)

It has been shown (Athas et al., 1994) that adiabatic switching can significantly reduce the dynamic power dissipation in an integrated circuit. Due to the overhead in the realization of adiabatic logic blocks (Saas et al., 2000) the best results are achieved when it is used only for charging dominant loads in an integrated circuit (Voss and Glessner, 2001). It has been demonstrated (Saas et al., 2001) that a multi stage driver is needed for minimal power dissipation. In this article a complete three stage driver including the generation of oscillating supply is described. To obtain a minimal power dissipation during synchronization the resonant frequency has to be constant. Therefore the waveforms for the logic states of the signal and the realization of a single stage differ from those presented in (Saas et al., 2001). In the H-SPICE simulations losses of the inductor are taken into account. This allows to estimate the power reduction that is achievable in a real system.

Saas, C.; Nossek, J. A.

2003-05-01

452

Charged Membranes  

NSDL National Science Digital Library

This Teaching Resource provides three animated lessons that describe the storage and utilization of energy across plasma membranes. The “Na,K ATPase” animation explains how these pumps establish the electrochemical gradient that stores energy across plasma membranes. The “ATP synthesizing complexes” animation shows how these complexes transfer energy from the inner mitochondrial membrane to adenosine triphosphate (ATP). The “action potential” lesson explains how charged membranes are used to propagate signals along the axons of neurons. These animations serve as valuable resources for any collegiate-level course that describes these important factors. Courses that might employ them include introductory biology, biochemistry, biophysics, cell biology, pharmacology, and physiology.

Jack D. Thatcher (Lewisburg;West Virginia School of Osteopathic Medicine REV)

2013-04-16

453

CHARGE Association  

PubMed Central

We present here a case of 17-year-old boy from Kolkata presenting with obesity, bilateral gynecomastia, mental retardation, and hypogonadotrophic hypogonadism. The patient weighed 70 kg and was of 153 cm height. Facial asymmetry (unilateral facial palsy), gynecomastia, decreased pubic and axillary hair, small penis, decreased right testicular volume, non-palpable left testis, and right-sided congenital inguinal hernia was present. The patient also had disc coloboma, convergent squint, microcornea, microphthalmia, pseudohypertelorism, low set ears, short neck, and choanalatresia. He had h/o VSD repaired with patch. Laboratory examination revealed haemoglobin 9.9 mg/dl, urea 24 mg/dl, creatinine 0.68 mg/dl. IGF1 77.80 ng/ml (decreased for age), GH <0.05 ng/ml, testosterone 0.25 ng/ml, FSH-0.95 ?IU/ml, LH 0.60 ?IU/ml. ACTH, 8:00 A.M cortisol, FT3, FT4, TSH, estradiol, DHEA-S, lipid profile, and LFT was within normal limits. Prolactin was elevated at 38.50 ng/ml. The patient's karyotype was 46XY. Echocardiography revealed ventricularseptal defect closed with patch, grade 1 aortic regurgitation, and ejection fraction 67%. Ultrasound testis showed small right testis within scrotal sac and undescended left testis within left inguinal canal. CT scan paranasal sinuses revealed choanalatresia and deviation of nasal septum to the right. Sonomammography revealed bilateral proliferation of fibroglandular elements predominantly in subareoalar region of breasts. MRI of brain and pituitary region revealed markedly atrophic pituitary gland parenchyma with preserved infundibulum and hypothalamus and widened suprasellar cistern. The CHARGE association is an increasingly recognized non-random pattern of congenital anomalies comprising of coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia, ear abnormalities, and/or deafness.[1] These anomalies have a higher probability of occurring together. In this report, we have described a boy with CHARGE association.

Chakraborty, Semanti; Chakraborty, Jayanta

2012-01-01

454

25 Gb\\/s AGC amplifier, 22 GHz transimpedance amplifier and 27.7 GHz limiting amplifier ICs using AlGaAs\\/GaAs-HEMTs  

Microsoft Academic Search

Automatic-gain-control (AGC), transimpedance, and limiting amplifiers are key elements in optical-fiber links and measuring equipment. This AGC amplifier and transimpedance amplifier are based on 0.3 ?m gate length HEMTs (fT=50 GHz). The limiting amplifier uses 0.2 ?m gate length (fT= 60 GHz) enhancement (e-mode) and depletion (d-mode) AlGaAs\\/GaAs HEMTs. The AGC amplifier has 18 GHz bandwidth and 30 dB maximum

Zhihao Lao; M. Berroth; V. Hurm; A. Thiede; R. Bosch; P. Hofmann; A. Hulsmann; C. Moglestue; K. Kohler

1997-01-01

455

Valves Based on Amplified Piezoelectric Actuators  

NASA Astrophysics Data System (ADS)

Amplified Piezo Actuators have been developed at CEDRAT TECHNOLOGIES for several years and found several applications in space. Their well-known advantages (rapid response and precise positioning) have been used in valve designs to obtain either rapid or fine proportional valves. A first gas valve is using a small amplified piezo actuator and is further driven with a switched amplifier to get a high frequency modulation. A frequency modulation higher than 400 Hz with a stroke of 100 m has been measured. These properties can also be used for gasoline injectors. A second gas valve is also using an amplified piezo actuator, a linear amplifier, and a servo controller to get an accurate proportional valve dedicated to precise gas flow control in the fields of instrumentation and space. A linear and stable flow control has been demonstrated. The low power consumption of the piezoelectric valve in the space applications is an additional advantage. A stable flow of dry Nitrogen ranging from 0.1 sccm to 200 sccm has been measured with an inlet pressure of 1 bar. These valves have been designed with the help of several modelling tools: finite element procedure for the electro-mechanical part, the contact mechanics between the poppet and the seat, the computational fluid dynamics. The valves have been further measured by using several measuring equipment's, including a laser interferometer, a spectrum analyser to measure the gas flow stability, Thermal vacuum and leak tests have also been performed. A special emphasis is realised on the driving and control aspects of this valve for space applications.

Le Letty, R.; Lhermet, N.; Patient, G.; Claeyssen, F.; Lang, M.

2004-10-01

456

Evaluation of immunoassays for the detection and typing of PCR amplified human papillomavirus DNA.  

PubMed Central

AIMS: To evaluate different hybridisation techniques to detect and type human papillomavirus (HPV) DNAs amplified by consensus primer polymerase chain reaction (PCR) in biopsy and cytological specimens. METHODS: A hybrid capture-immunoassay in microtitre wells was performed to detect HPV sequences amplified by PCR and typed by specific oligoprobes. Consensus primers were used to amplify a sequence within the L1 open reading frame, and direct digoxigenin labelling of amplified products was performed during the amplification reaction. The amplified product was separately hybridised with six biotinylated type specific probes (HPV6, 11, 16, 18, 31, and 33); hybrids were then captured into streptavidin coated microtitre wells and detected by a spectrophotometer as an ELISA using antidigoxigenin Fab fragment labelled with peroxidase and a colorimetric substrate. The results were compared with the dot-blot immunoassay used to detect and type PCR amplified HPV DNA sequences. Consensus primers were used to generate the same unlabelled PCR product; digoxigenin labelled type specific probes for HPV6, 11, 16, 18, 31, and 33 were used and hybrids visualised by colorimetric immunoenzymatic reaction. Thirty nine biopsy specimens and 31 cytological samples were tested by the PCR-ELISA and by standard PCR followed by dot-blot hybridisation. RESULTS: The PCR-ELISA proved to be more sensitive than standard PCR with dot-blot hybridisation typing. All samples positive for HPV-DNA in standard PCR with dot-blot hybridisation method were confirmed positive by the PCR-ELISA assay; however, seven samples were positive only by PCR-ELISA. CONCLUSIONS: The PCR-ELISA assay, which can be performed in one day, is easily standardised and therefore seems to be a practical, sensitive, and reliable diagnostic tool for the detection and typing of HPV genomes in biopsy and in cytological specimens in the routine diagnostic laboratory.

Venturoli, S; Zerbini, M; La Placa, M; D'Antuono, A; Negosanti, M; Gentilomi, G; Gallinella, G; Manaresi, E; Musiani, M

1998-01-01

457

Palm size charging platform with uniform wireless power transfer  

Microsoft Academic Search

In this paper, the design of wireless inductive charger for portable electronic devices is present. There are two main parts have been included. The first part is the exciting circuit in which to provide sufficient input power to the primary charging platform. The exciting circuit is comprised by oscillator circuit and power amplifier circuit. Both of the two circuits have

Yun You; Boon-Hee Soong; Selvakumaran Ramachandran; Wei Liu

2010-01-01

458

Recent Developments in Space-Charge Control Tubes  

Microsoft Academic Search

In spite of being the oldest in the family of electron tubes, the space-charge control tube or conventional tube continues to experience continual development and improvement. Recent developments include extensions of power-frequency limits, improvements in emission, and extensive improvements of structure. Of particular novelty are a high gm tube using secondary emission multiplication and a distributed-amplifier type tube.

Karl Spangenberg

1962-01-01

459

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

SciTech Connect

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.

Not Available

1988-10-25

460

A 10 Gbase-LX4 receiver front end transimpedance amplifier and limiting amplifier  

Microsoft Academic Search

ABSTRACT A 10 Gbase-LX4 receiver front end including an inductor feedback,transimpedance ,amplifier ,and ,a modified Cherry-Hooper cell limiting amplifier realized in a 0.18µm CMOS process is described. The receiver front end covers 34.8 dB input dynamic,range and provides 66 dB? differential gain with 1.7 GHz bandwidth. All the building blocks achieve a high ,data rate with low power dissipation. The

Hung-chieh Tsai; Jyh-yih Yeh; Wei-hsuan Tu; Tai-cheng Lee; Chorng-kuang Wang

2004-01-01

461

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

Microsoft Academic Search

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

Shoichi NARAHASHI; T. Nojima

1991-01-01

462

Large-screen projection displays with laser brightness amplifiers  

NASA Astrophysics Data System (ADS)

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.

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

1997-05-01

463

6-k?, 43Gb\\/s differential transimpedance-limiting amplifier with auto-zero feedback and high dynamic range  

Microsoft Academic Search

A high-gain, 43-Gb\\/s InP HBT transimpedance-limiting-amplifier (TIALA) with 100-?App sensitivity and 4.5-mApp input overload current is presented. The circuit also operates as a limiting amplifier with 40-dB differential gain, better than -15-dB input return loss, and a record-breaking sensitivity of 8 mVpp at 43 Gb\\/s. It features a differential TIA stage with inductive noise suppression in the feedback network and

Hai Tran; Florin Pera; Douglas S. McPherson; Dorin Viorel; S. P. Voinigescu

2003-01-01

464

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

Microsoft Academic Search

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

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

2007-01-01

465

Development of a Transimpedance Amplifier for Cryotemperatures, Study.  

National Technical Information Service (NTIS)

Design, construction and measured data of three versions of a monolithic transimpedance amplifier for cryotemperatures are described. The amplifier is implemented in Si-gate-CMOS technology and provided with a MOSFET, a process-compatible JFET and an open...

U. Brunsmann O. Frenzl G. Zimmer M. Wrede

1984-01-01

466

Investigation of a Background Suppression Transimpedance Amplifier for Photovoltaic Detectors.  

National Technical Information Service (NTIS)

The current generation of transimpedance amplifier based detector systems are limited by opamp saturation when operating at a high gain or in the presence of a large background signal. To eliminate saturation, an amplifier that is frequency dependent is d...

F. J. Metzger

1992-01-01

467

Transient Suppression Circuit for Push-Pull Switching Amplifiers.  

National Technical Information Service (NTIS)

The patent application describes a protective coupling circuit located between the D.C. supply voltage and the amplifier components of a push-pull switching amplifier to suppress transients created during switching. The coupling circuit comprises a power ...

H. W. Lord J. D. Rogers

1976-01-01

468