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1

High sensitivity charge amplifier for ion beam uniformity monitor  

DOEpatents

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

Johnson, Gary W. (Livermore, CA)

2001-01-01

2

Note: A charge sensitive spectroscopy amplifier for position sensitive micro-channel plate detectors.  

PubMed

A compact and low noise charge sensitive spectroscopy amplifier which can be integrated into position sensitive micro-channel plate (MCP) detectors has been constructed. The amplifier was optimized by using a wave form generator and tested by a chevron shape MCP detector. The output noise of 4 mV(rms) was achieved while the gain is 10(12) V/C and the shaping time is 700 ns. PMID:25362463

Wang, Wei; Yu, Deyang; Liu, Junliang; Lu, Rongchun; Cai, Xiaohong

2014-10-01

3

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

4

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

PubMed

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

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

2015-03-01

5

Temperature sensitivity of ytterbium fiber amplifiers  

Microsoft Academic Search

We demonstrated a method of characterizing temperature sensitivity of ytterbium-doped fiber amplifiers based on deriving Stark parameters from measured emission and absorption spectra. Temperature sensitivity is found to be mainly determined by Pout\\/Ppump, when Pout\\/Ppump>0.4.

Xiang Peng; Liang Dong

2008-01-01

6

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

DOEpatents

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

DeGeronimo, Gianluigi

2006-02-14

7

Monolithic integrated circuit charge amplifier and comparator for MAMA readout  

NASA Technical Reports Server (NTRS)

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

Cole, Edward H.; Smeins, Larry G.

1991-01-01

8

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

E-print Network

Charge Recycling Sense Amplifier Based Logic: Securing Low Power Security IC's against Differential Charge Recycling Sense Amplifier Based Logic is presented. This logic is derived from Sense Amplifier advanced circuit techniques to reduce the power consumption of SABL. Charge Recycling SABL (CRSABL

9

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

SciTech Connect

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

Bazghaleh, Mohsen, E-mail: mohsen.bazghaleh@adelaide.edu.au; Grainger, Steven; Cazzolato, Ben; Lu, Tien-Fu [School of Mechanical Engineering, The University of Adelaide, North Terrace, South Australia 5005 (Australia)] [School of Mechanical Engineering, The University of Adelaide, North Terrace, South Australia 5005 (Australia); Oskouei, Reza [School of Computer Science, Engineering and Mathematics, Flinders University, Bedford Park, South Australia 5042 (Australia)] [School of Computer Science, Engineering and Mathematics, Flinders University, Bedford Park, South Australia 5042 (Australia)

2014-04-15

10

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

PubMed Central

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

2014-01-01

11

Improved current and charge amplifiers for driving piezoelectric loads  

Microsoft Academic Search

Piezoelectric transducers are known to exhibit less hysterisis when driven with current or charge rather than voltage. Despite this advantage, such methods have found little practical application due to the poor low frequency response of present current and charge driver designs. This paper introduces the compliance feedback current driver containing a secondary voltage feedback loop to prevent DC charging of

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

2003-01-01

12

Improved current and charge amplifiers for driving piezoelectric loads  

Microsoft Academic Search

Piezoelectric transducers are known to exhibit less hysterisis when driven with current or charge rather than voltage. Despite this advantage, such methods have found little practical application due to the poor low frequency response of present current and charge driver designs. This paper introduces the compliance feedback current driver containing a secondary voltage feedback loop to prevent DC charging of

Andrew J. Fleming; S. O. Reza Moheimani

13

High-sensitivity bunch charge monitor  

NASA Astrophysics Data System (ADS)

The conceptual design for a high-sensitivity bunch charge monitor is presented. The device operates with short, spaced bunches. For optimal performance, the bunch duration should be less than 10 ns and bunch spacing should be more than 100 ns. Sensitivity of the monitor is close to 10 V per nanocoulomb. The equivalent scheme and the output signal shape are also presented. Such a monitor seems to be promising for the bunch charge measurements of beams like those in TESLA or ILC projects.

Lebedev, N. I.; Fateev, A. A.

2008-12-01

14

Logical Effort Delay Modeling of Sense Amplifier Based Charge Recycling Threshold Logic Gates  

E-print Network

1 Logical Effort Delay Modeling of Sense Amplifier Based Charge Recycling Threshold Logic Gates Peter Celinski1,2 , Sorin Cotofana2 and Derek Abbott1 1 The Department of Electrical and Electronic of circuits based on the Charge Recycling Threshold Logic (CRTL) gate implementation is addressed. A delay

Kuzmanov, Georgi

15

HYBRID DC ACCURATE CHARGE AMPLIFIER FOR LINEAR PIEZOELECTRIC POSITIONING  

Microsoft Academic Search

Abstract: Piezoelectric transducers are known,to exhibit l ess hysterisis when,driven with current or charge rather than voltage. Despite this advanta ge, such methods have found little practical application due to the poor low frequency response of present current and charge driver designs. This paper introduces a new circuit topology free from low-frequency drift and DC load offsets. The hybrid load

Andrew J. Fleming; S. O. Reza Moheimani

16

Realization of a Charge Transformer; A Noise Matching Device for Single Electron Transistor Amplifiers.  

NASA Astrophysics Data System (ADS)

We present a new device, called a charge transformer, which can be used to enhance noise performance of single electron transistor (SET) amplifiers when placed between a low capacitance SET and a high capacitance device under test. The function of a charge transformer is analogous to that of a flux transformer commonly used with superconducting quantum interference devices (SQUIDs). A prototype charge transformer consisting of 4 identical capacitors and 13 switches is fabricated using a GaAs/AlGaAs heterostructure with a two-dimensional electron gas. The switches enable capacitors to be connected either in series or in parallel. During operation the capactiors switch back and forth between the parallel and series configuration with clock frequencies up to 3 MHz. We believe SET amplifiers integrated with a charge transformer on the same chip, may find applications in various fields where low-noise electrometers are needed. Fabrication and noise analysis of the charge transformer will be discussed.

Lewis, Kim; Kurdak, Cagliyan; Krishna, S.; Bhattacharya, P.

2002-03-01

17

Position Sensitive Detection System for Charged Particles  

SciTech Connect

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

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

2012-01-01

18

Conformation sensitive charge transport in conjugated polymers  

SciTech Connect

Temperature dependent charge carrier mobility measurements using field effect transistors and density functional theory calculations are combined to show how the conformation dependent frontier orbital delocalization influences the hole- and electron mobilities in a donor-acceptor based polymer. A conformationally sensitive lowest unoccupied molecular orbital results in an electron mobility that decreases with increasing temperature above room temperature, while a conformationally stable highest occupied molecular orbital is consistent with a conventional hole mobility behavior and also proposed to be one of the reasons for why the material works well as a hole transporter in amorphous bulk heterojunction solar cells.

Mattias Andersson, L., E-mail: matan@ifm.liu.se [Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping SE-581 83 (Sweden); Hedström, Svante; Persson, Petter [Division of Theoretical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund (Sweden)] [Division of Theoretical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund (Sweden)

2013-11-18

19

Low-noise charge sensitive readout for pyroelectric sensor arrays using PVDF thin film  

Microsoft Academic Search

The paper presents a fully integrated low-noise readout circuit for the purpose of front-end amplification in pyroelectric infrared focal plane arrays (IRFPA). A low-noise and low-power charge sensitive amplifier (CSA) has been fabricated and characterised in a standard CMOS process. A value of 11.4 nV\\/?Hz at 100 Hz input referred noise voltage has been measured for a maximum power dissipation

H. J Weller; D Setiadi; T. D Binnie

2000-01-01

20

Preexisting oncogenic events impact trastuzumab sensitivity in ERBB2-amplified gastroesophageal adenocarcinoma  

PubMed Central

Patients with gastric and esophageal (GE) adenocarcinoma tumors in which the oncogene ERBB2 has been amplified are routinely treated with a combination of cytotoxic chemotherapy and the ERBB2-directed antibody trastuzumab; however, the addition of trastuzumab, even when tested in a selected biomarker-positive patient population, provides only modest survival gains. To investigate the potential reasons for the modest impact of ERBB2-directed therapies, we explored the hypothesis that secondary molecular features of ERBB2-amplified GE adenocarcinomas attenuate the impact of ERBB2 blockade. We analyzed genomic profiles of ERBB2-amplified GE adenocarcinomas and determined that the majority of ERBB2-amplified tumors harbor secondary oncogenic alterations that have the potential to be therapeutically targeted. These secondary events spanned genes involved in cell-cycle regulation as well as phosphatidylinositol-3 kinase and receptor tyrosine kinase signaling. Using ERBB2-amplified cell lines, we demonstrated that secondary oncogenic events could confer resistance to ERBB2-directed therapies. Moreover, this resistance could be overcome by targeting the secondary oncogene in conjunction with ERBB2-directed therapy. EGFR is commonly coamplified with ERBB2, and in the setting of ERBB2 amplification, higher EGFR expression appears to mark tumors with greater sensitivity to dual EGFR/ERBB2 kinase inhibitors. These data suggest that combination inhibitor strategies, guided by secondary events in ERBB2-amplified GE adenocarcinomas, should be evaluated in clinical trials. PMID:25401468

Kim, Jihun; Fox, Cameron; Peng, Shouyong; Pusung, Mark; Pectasides, Eirini; Matthee, Eric; Hong, Yong Sang; Do, In-Gu; Jang, Jiryeon; Thorner, Aaron R.; Van Hummelen, Paul; Rustgi, Anil K.; Wong, Kwok-Kin; Zhou, Zhongren; Tang, Ping; Kim, Kyoung-Mee; Lee, Jeeyun; Bass, Adam J.

2014-01-01

21

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

PubMed

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

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

2014-11-17

22

Charge Transformer to Enhance Noise Performance of Single Electron Transistor Amplifiers in High Capacitance Applications.  

NASA Astrophysics Data System (ADS)

We propose a new device, called a charge transformer, which can be used to enhance noise performance of single electron transistor (SET) amplifiers in applications where a large capacitance macroscopic device needs to be measured. The function of a charge transformer is analogous to that of a flux transformer commonly used with superconducting quantum interference devices (SQUIDs). Our charge transformer consists of N identical capacitors and switches that enable capacitors to be connected either in series or in parallel. The capacitors will be switched back and forth between the parallel and series configurations with speeds faster than the signals that will be measured. To achieve optimum noise performance, we choose N and the capacitance such that in series and parallel configurations, the equivalent capacitance will be matched to the gate capacitance of the SET and the capacitance of the device under test, respectively. The fabrication of the charge transformer using GaAs/AlGaAs heterostructures and its practical limitations will be discussed.

Lewis, K. M.; Kurdak, C.

2001-03-01

23

Phase-sensitive Manipulations of Squeezed Vacuum Field in an Optical Parametric Amplifier inside an Optical Cavity  

E-print Network

Squeezed vacuum field can be amplified or deamplified when it is injected, as the signal beam, into a phase-sensitive optical parametric amplifier (OPA) inside an optical cavity. The spectral features of the reflected quantized signal field are controlled by the relative phase between the injected squeezed vacuum field and the pump field for the OPA. The experimental results demonstrate coherent phenomena of OPA in the quantum regime, and show phase-sensitive manipulations of quantum fluctuations for quantum information processing.

Jing Zhang; Chenguang Ye; Feng Gao; Min Xiao

2008-11-02

24

Improved Sensitivity Mass Spectrometric Detection of Eicosanoids by Charge Reversal  

E-print Network

Improved Sensitivity Mass Spectrometric Detection of Eicosanoids by Charge Reversal Derivatization of underivatized analytes. This charge reversal derivatization allows detec- tion of cations rather than anions (for example, refs 1-3). With these methods it is possible to analyze a large collection of eicosanoids

Gelb, Michael

25

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

NASA Astrophysics Data System (ADS)

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

Klaus, Leonard; Bruns, Thomas; Volkers, Henrik

2015-02-01

26

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

PubMed

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 of DNA scored for polymorphism per primer averaged 13.2 kb, or 0.0001% of the typical sugarcane genome size of 1.2 × 107 kb (2C). RAPD analysis of sugarcane plants regenerated from embryogenic callus revealed very few polymorphisms, indicating that gross genetic change is infrequent during this tissue culture procedure, although epigenetic effects result in transient morphological changes in regenerated plants. More sensitive variations on the RAPD technique may increase the practicality of DNA-based screening of regenerated plant lines to reveal somaclonal variants. PMID:24173080

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

1995-06-01

27

Power evolution along phase-sensitive parametric amplifiers: an experimental survey.  

PubMed

We propose and experimentally demonstrate a method based on Brillouin optical time-domain analysis to measure the longitudinal signal power distribution along phase-sensitive fiber-optical parametric amplifiers (PS-FOPAs). Experimental results show that the amplification of a PS-FOPA could go through different longitudinal profiles and yet finish with the same overall gain. This behavior is in sheer contrast with theoretical expectations, according to which longitudinal gain distribution should follow certain profiles determined by the initial relative phase difference but can never end up in the same overall gain. The gap between theory and experiment only becomes evident when the pump wavelength is within the fluctuation range of the zero dispersion wavelength (ZDW) of the PS-FOPA. PMID:25361292

Alishahi, Fatemeh; Vedadi, Armand; Shoaie, Mohammad Amin; Soto, Marcelo A; Denisov, Andrey; Mehrany, Khashayar; Thévenaz, Luc; Brès, Camille-Sophie

2014-11-01

28

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

29

Dry-etch characteristics of chemically amplified and onium-salt-sensitized electron-beam resists  

NASA Astrophysics Data System (ADS)

Electron beam resists having high sensitivity and high resistance to dry etching are under investigation for sub-half micron device production using 5x reticle masks. The effects of dry etch process conditions on the performance of the novolac based chemically amplified AZPN114 and onium salt sensitized EPR resist have been investigated at 20 keV and 10 keV electron beam energies using an electron beam microfabricator under a range of dose, post- exposure bake, and development conditions. Linewidths in the range from 4 micrometers down to 0.2 micrometers have been evaluated. Pattern transfer to chromium on quartz was carried out in a commercial reactive ion etcher. A comprehensive series of RIE experiments were devised and analyzed using a commercial statistical software package. CD measurements on resist lines and also on chromium lines after dry etch, were carried out both in a field emission SEM and with a calibrated optical linewidth measuring system. A focused ion beam system was used to microsection selected resist lines on chromium and dry etched chromium lines for edge profile inspection.

Huq, Syed E.; Prewett, Philip D.

1994-05-01

30

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

31

Calculation of DC space-charge fields in a traveling-wave amplifier in the large signal regime  

Microsoft Academic Search

A fully two-dimensional (2-D) dc space charge model has been implemented in a large-signal traveling-wave amplifier code. The simulation algorithm takes an iterative approach by alternately solving the Poisson equation and the beam trajectory equations to converge toward a self-consistent steady-state solution. This approach is similar to that employed in steady-state gun codes. However, it is well known from gun

Chia-Lie Chang; D. P. Chernin; B. Levush; E. M. Nelson; J. J. Petillo; D. R. Whaley

2004-01-01

32

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

33

Influence of statistical gain fluctuations of the high-frequency amplifier on the sensitivity of a Dicke-Radiometer  

Microsoft Academic Search

The influence of statistical gain fluctuations of the high-frequency amplifier on the sensitivity of a Dicke radiometer with selective videoamplifier is calculated with methods that are used in describing random processes. It is shown that the radiometer sensitivity depends on the power density spectrumSg(f) of the gain fluctuations for a Dicke-radiometer of the zero-balanced as well as the unbalanced type.

Andreas Magun; Klaus Künzi

1971-01-01

34

Space-charge limits of ion sensitive probes  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

35

Phase regeneration of a star-8QAM signal in a phase-sensitive amplifier with conjugated pumps.  

PubMed

We demonstrate numerically phase regeneration of a star-8QAM signal with two amplitude and four phase states in a phase-sensitive amplifier. In a dual-stage setup, two phase-conjugated idlers are generated in a first stage consisting of two fiber-optic parametric phase-insensitive amplifiers operated in highly nonlinear gain regime. These are used as pumps in the second, phase-sensitive amplification stage which enables efficient phase regeneration via a degenerate four-wave-mixing process. The latter can be operated in two different operation modes: without format conversion or with phase-shifted amplitude levels. In both regimes, we observe high phase-regeneration efficiency for all amplitude levels: the initial phase noise with 0.2 rad standard deviation is reduced by a factor of 5. PMID:24515062

Stiller, B; Onishchukov, G; Schmauss, B; Leuchs, G

2014-01-13

36

Numerical analysis of the signal gain and noise figure of Yb 3 + -sensitized Er 3 + -doped fiber amplifiers at different pumping power configurations  

Microsoft Academic Search

The gain performance and noise figure of ytterbium (Yb3+)-sensitized erbium (Er3+)-doped fiber amplifiers (EYDFAs) with a small numerical aperture of 0.16 are theoretically modelled. Taking into account the upconversion effect from the Er3+ levels (4I13\\/2 and 4I11\\/2), the Yb3+?Er3+ energy transfer by cross-relaxation, the amplified spontaneous emission (ASE) as well as background losses, an amplifier model capable of obtaining a

Cüneyt Berkdemir; Sedat Özsoy

2008-01-01

37

Gain and noise in ytterbium-sensitized erbium-doped fiber amplifiers: measurements and simulations  

Microsoft Academic Search

The fiber gain and noise figure in erbium (Er)-ytterbium (Yb) codoped fiber amplifiers are experimentally studied and theoretically modeled. The different fiber parameters for the model are found in separate characterization measurements. The comparison between the measured and calculated data show excellent agreement. In addition, we demonstrate the design process for a specific cladding-pumped fiber to find the optimum fiber

Martin Achtenhagen; Robert James Beeson; Feng Pan; Bruce Nyman; Amos Hardy

2001-01-01

38

Experimental and theoretical studies on ytterbium sensitized erbium-doped fiber amplifier  

Microsoft Academic Search

The performance of a high power erbium–ytterbium doped fiber amplifier (EYDFA) is investigated experimentally and theoretically. The EYDFA provides a flat gain with an output power higher than 23dBm in the wavelength region from 1541 to 1565nm using a multimode pumping at 927nm. In the theoretical analysis, the rate and power propagation equations are solved to examine the effect of

M. R. A. Moghaddam; S. W. Harun; R. Parvizi; Z. S. Salleh; H. Arof; A. Lokman; H. Ahmad

2011-01-01

39

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

40

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

41

Charge transport in dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

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

Yanagida, Masatoshi

2015-03-01

42

Sensitivity Analysis of Combustion Timing and Duration of Homogeneous Charge Compression Ignition (HCCI) Engines  

E-print Network

Sensitivity Analysis of Combustion Timing and Duration of Homogeneous Charge Compression Ignition of a Homogeneous Charge Com- pression Ignition (HCCI) engine. Qualitative and quantitative information combustion in spark ignition (SI) and compression ignition (CI) engines, respectively [2]. Indeed, controlled

Stefanopoulou, Anna

43

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

44

The Aurora kinase inhibitor CCT137690 downregulates MYCN and sensitizes MYCN-amplified neuroblastoma in vivo  

PubMed Central

The Aurora kinases regulate key stages of mitosis including centrosome maturation, spindle assembly, chromosome segregation and cytokinesis. Aurora A and B overexpression has also been associated with various human cancers and as such, they have been extensively studied as novel anti-mitotic drug targets. Here we characterise the Aurora kinase inhibitor CCT137690, a highly selective, orally bioavailable imidazo[4,5-b]pyridine derivative that inhibits Aurora A and B kinases with low nanomolar IC50 values in both biochemical and cellular assays and exhibits anti-proliferative activity against a wide range of human solid tumour cell lines. CCT137690 efficiently inhibits histone H3 and TACC3 phosphorylation (Aurora B and Aurora A substrates, respectively) in HCT116 and HeLa cells. Continuous exposure of tumour cells to the inhibitor causes multipolar spindle formation, chromosome misalignment, polyploidy and apoptosis. This is accompanied by p53/p21/BAX induction, thymidine kinase 1 (TK1) downregulation and PARP cleavage. Furthermore, CCT137690 treatment of MYCN-amplified neuroblastoma cell lines inhibits cell proliferation and decreases MYCN protein expression. Importantly, in a transgenic mouse model of neuroblastoma (TH-MYCN) that overexpresses MYCN protein and is predisposed to spontaneous neuroblastoma formation, this compound significantly inhibits tumour growth. The potent preclinical activity of CCT137690 suggests that this inhibitor may benefit patients with MYCN amplified neuroblastoma. PMID:21885865

Faisal, Amir; Vaughan, Lynsey; Bavetsias, Vassilios; Sun, Chongbo; Atrash, Butrus; Avery, Sian; Jamin, Yann; Robinson, Simon P.; Workman, Paul; Blagg, Julian; Raynaud, Florence I.; Eccles, Suzanne A.; Chesler, Louis; Linardopoulos, Spiros

2015-01-01

45

The hardness based molecular charge sensitivities and their use in the theory of chemical reactivity  

Microsoft Academic Search

Basic concepts, rules and relations of the charge sensitivity analysis (CSA) of molecular systems, and recent illustrative applications of selected charge sensitivities as reactivity indices, have been surveyed. The method, originating from the density functional theory, determines various hardnesses, softnesses and the Fukui function indices (global and regional), from the corresponding canonical hardness tensor (or kernel), via the electronegativity equalization

R. Nalewajski; R. Ingardena

46

Charge structure and lightning sensitivity in a simulated multicell thunderstorm  

Microsoft Academic Search

A three-dimensional dynamic cloud model is used to investigate electrification of the full life cycle of an idealized continental multicell storm. Five laboratory-based parameterizations of noninductive graupel-ice charge separation are compared. Inductive (i.e., electric field-dependent) charge separation is tested for rebounding graupel-droplet collisions. Each noninductive graupel-ice parameterization is combined with variations in the effectiveness of inductive charging (off, moderate, and

Edward R. Mansell; Donald R. MacGorman; Conrad L. Ziegler; Jerry M. Straka

2005-01-01

47

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

PubMed

Riparian or streamside zones support dynamic ecosystems with three interacting components: flowing water, alluvia (river-transported sediments), and vegetation. River damming influences all three, and subsequent responses can provide insight into underlying processes. We investigated these components along the 315-km Hells Canyon corridor of the Snake River that included reaches upstream, along, and downstream from three large dams and reservoirs, and along the Salmon River, a free-flowing tributary. Sandbar willow was generally the woody plant at the lowest bank position and was abundant along upstream reaches (53, 45, 67% of transects), sparse along reservoirs (11, 12, 0%), and sparse along the Snake River downstream (11%). It was prolific along the undammed Salmon River (83%) and intermediate along the Snake River below the Salmon inflow (27%), indicating partial recovery with the contribution of water and sediments. Along these rivers, it commonly occurred on sandy substrates, especially on shallow-sloped surfaces, and emerged from interstitial sands between cobbles on steeper surfaces. However, along the Snake River below the dams, sandbars have eroded and willows were sparse on remnant, degrading sand surfaces. We conclude that a feedback loop exists between sands and sandbar willow. Sand favors willow colonization and clonal expansion, and reciprocally the extensively branched willows create slack-water zones that protect and trap sands. This feedback may sustain surface sands and sandbar willows along free-flowing river systems and it amplifies their mutual vulnerability to river damming. Following damming, sediment-depleted water is released downstream, eroding surface sands and reducing willow colonization and expansion. With willow decline, sands are further exposed and eroded, compounding these impacts. From this feedback, we predict the coordinated depletion of surface sands and riparian willows along dammed rivers throughout the Northern Hemisphere. PMID:20803218

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

2011-01-01

48

Application of system-identification by ARMarkov and sensitivity analysis to noise-amplifier models  

NASA Astrophysics Data System (ADS)

Separated flow often exhibit amplification of external noise sources via an interaction with shear layer instabilities. In order to manipulate this amplification process we consider a data-based control design strategy. The first step is to build a state-space representation of the input-output transfer function. An auto-regressive representation is used that explicitly includes Markov parameters (ARMarkov). This is then coupled with the eigensystem realization algorithm (ERA) which yields a reduced-order state-space representation of the problem. In real experiments the data is contaminated by measurement noise or by non-linearities which are not accounted for by the present approach. In order to enforce robustness of the identification-realization procedure a sensitivity analysis of the algorithm is performed. These sensitivities provide quantitative criteria to find the most robust way of identifying the system using the ARMarkov/ERA algorithm. The system-identification and sensitivity framework will be demonstrated on the Ginzburg-Landau equation. Support from the Partner University Fund (PUF) is gratefully acknowledged.

Dovetta, Nicolas; Schmid, Peter; Sipp, Denis; McKeon, Beverley

2011-11-01

49

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

50

Sensitive enantioanalysis of ?-blockers via field-amplified sample injection combined with water removal in microemulsion electrokinetic chromatography.  

PubMed

In this study, an on-line sample preconcentration technique, field-amplified sample injection combined with water removal by electroosmotic flow (EOF) pump, was applied to realize a highly sensitive chiral analysis of ?-blocker enantiomers by MEEKC. The introduction of a water plug in capillary before the electrokinetic injection provided the effective preconcentration of chiral compounds. And then the water was moving out of the column from the injection end under the effect of the EOF, which avoided dilution of the stacked ?-blocker enantiomers concentration suffering from the presence of water in separation buffer. Moreover, the addition of H3 PO4 and methanol in the sample solution greatly improved the enhancement efficiency further. Under optimized conditions, more than 2700-fold enhancement in sensitivity was obtained for each enantiomer of bupranolol (BU), alprenolol (AL), and propranolol (PRO) via electrokinetic injection. LODs were 0.10, 0.10, 0.12, 0.11, 0.02, and 0.02 ng/mL for S-BU, R-BU, S-AL, R-AL, S-PRO, and R-PRO, respectively. Eventually, the proposed method was successfully applied to the determination of BU, AL, and PRO in serum samples with good recoveries ranging from 93.4 to 98.2%. PMID:24798241

Ma, Yanhua; Zhang, Huige; Rahman, Zia Ur; Wang, Weifeng; Li, Xi; Chen, Hongli; Chen, Xingguo

2014-10-01

51

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

PubMed

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

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

2015-03-24

52

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 1X consisting of benzophenone linked by a phosphodiester to one of the natural nucleosides X = A, G, T, C were studied in water and methanol. The theoretical work focuses on the dynamics and electronic structure of 1G. Predominant conformations in the two solvents were obtained by molecular dynamics simulations. 1G 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 1G 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 1X 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 1A and 6.0 × 10(9) s(-1) for 1G. 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 H(AB) = 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

2013-11-14

53

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

E-print Network

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

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

2004-07-13

54

Burial-nutrient feedbacks amplify the sensitivity of atmospheric carbon dioxide to changes in organic matter remineralisation  

NASA Astrophysics Data System (ADS)

Changes in the marine remineralisation of particulate organic matter (POM) and calcium carbonate potentially provide a positive feedback with atmospheric CO2 and climate change. The responses to changes in remineralisation length scales are systematically mapped with the Bern3D ocean-sediment model for atmospheric CO2 and tracer fields for which observations and palaeoproxies exist. Results show that the "sediment burial-nutrient feedback" amplifies the response in atmospheric CO2 by a factor of four to seven. A transient imbalance between the weathering flux and the burial of organic matter and calcium carbonate lead to sustained changes in the ocean's phosphate and alkalinity inventory and in turn in surface nutrient availability, marine productivity, and atmospheric CO2. It takes decades to centuries to reorganise tracers and fluxes within the ocean, many millennia to approach equilibrium for burial fluxes, while ?13C signatures are still changing 200 000 years after the perturbation. At 1.7 ppm m-1, atmospheric CO2 sensitivity is about fifty times larger for a unit change in the remineralisation depth of POM than of calcium carbonate. The results highlight the role of organic matter burial in atmospheric CO2 and the substantial impacts of seemingly small changes in POM remineralisation.

Roth, R.; Ritz, S. P.; Joos, F.

2014-10-01

55

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

PubMed Central

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

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

1994-01-01

56

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

57

Charge Sensitivity Enhancement via Mechanical Oscillation in Suspended Carbon Nanotube Devices.  

PubMed

Single electron transistors (SETs) fabricated from single-walled carbon nanotubes (SWNTs) can be operated as highly sensitive charge detectors reaching sensitivity levels comparable to metallic radio frequency SETs (rf-SETs). Here, we demonstrate how the charge sensitivity of the device can be improved by using the mechanical oscillations of a single-walled carbon nanotube quantum dot. To optimize the charge sensitivity ?Q, we drive the mechanical resonator far into the nonlinear regime and bias it to an operating point where the mechanical third order nonlinearity is canceled out. This way we enhance ?Q, from 6 ?e/(Hz)(1/2) for the static case to 0.97 ?e/(Hz)(1/2) at a probe frequency of ?1.3 kHz. PMID:25662034

Häkkinen, Pasi; Isacsson, Andreas; Savin, Alexander; Sulkko, Jaakko; Hakonen, Pertti

2015-03-11

58

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

59

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

Microsoft Academic Search

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

Mark Busman; Jan Sunner; Curtis R. Vogel

1991-01-01

60

Fluorescence characteristics and energy transfer of ytterbium-sensitized erbium-doped fluorophosphate glass for amplifier applications  

NASA Astrophysics Data System (ADS)

Yb3+/Er3+ codoped fluorophosphate glass has been investigated for developing broadband waveguide amplifier application. Spectroscopic properties and energy transfer microparameters of prepared glasses have been discussed. The spectral components of 1.55 ?m emission are analyzed and an equivalent four-level system is proposed to estimate the stark splitting for the 4I15/2 and 4I13/2 levels in Er3+ doped fluorophosphate glass. The results indicate that highly doped Yb3+ ions could transfer energy to Er ions efficiently in fluorophosphate glass and Er3+/Yb3+ doped fluorophosphate glass is preferable for broadband Er3+-doped waveguide amplifier application.

Tian, Ying; Wei, Tao; Chen, Fangze; Jing, Xufeng; Zhang, Junjie; Xu, Shiqing

2014-01-01

61

Experimental comparison of discrete and CMOS charge sensitive preamplifiers for CZT radiation detectors  

Microsoft Academic Search

During recent years, many readout integrated circuits for CdZnTe (CZT) radiation detectors have been studied particularly for use on pixellated detectors in imaging applications. The fundamental challenge is to keep noise performance similar to discrete preamplifiers, even with lower power. This paper presents an experimental evaluation of CMOS integrated charge sensitive preamplifiers intended for CZT radiation detectors using a comparison

Guillaume Montémont; Jean-Pierre Rostaing; Loïck Verger

2003-01-01

62

Gated charged-particle trap  

DOEpatents

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

Benner, W. Henry (Danville, CA)

1999-01-01

63

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

PubMed

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

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

2015-01-01

64

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

NASA Astrophysics Data System (ADS)

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

Saeki, Akinori; Kozawa, Takahiro; Tagawa, Seiichi

2009-07-01

65

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

NASA Astrophysics Data System (ADS)

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

Fang, Yami; Jing, Jietai

2015-02-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

67

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

PubMed

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

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

2014-01-01

68

Low noise charge sensitive preamplifier DC stabilized without a physical resistor  

DOEpatents

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

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

1994-09-13

69

Low noise charge sensitive preamplifier DC stabilized without a physical resistor  

DOEpatents

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

Bertuccio, Giuseppe (Brianza, IT); Rehak, Pavel (Patchogue, NY); Xi, Deming (Beijing, CN)

1994-09-13

70

A sensitive enzyme-linked immunosorbent assay amplified by biotin-streptavidin system for detecting non-steroidal anti-inflammatory drug ketoprofen.  

PubMed

A sensitive biotin-streptavidin-amplified enzyme-linked immunosorbent assay (BA-ELISA) method was developed for detecting non-steroidal anti-inflammatory drug ketoprofen. Compared with traditional ELISA method, the sensitivity of proposed immunoassay was enhanced by the biotin-streptavidin system. Under the optimal condition, the median inhibitory concentration (IC50) was 0.25 ng mL(-1), with minor cross-reactivity to a number of structural analogs. This developed assay was successfully applied to detect the ketoprofen residues in different fish samples, and good recoveries (72.6-105.5%) were obtained. The results indicated that this immunoassay method could specifically detect trace ketoprofen residues and could be widely used for routine monitoring of food samples. PMID:24762178

Bu, Dan; Zhuang, Hui S; Yang, Guang X

2014-06-01

71

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

72

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

73

Regional Matching of Atomic Softnesses in Chemical Reactions:  A Two-Reactant Charge Sensitivity Study  

Microsoft Academic Search

A semiempirical charge sensitivity analysis in atomic resolution is used to examine the regional softness parameters within two pairs of coordinating atoms in cyclization reactions, in a search for possible softness matching rules to be used as diagnostic tools for predicting regiochemistry trends. The cycloaddition reactions of a few typical 1,3-dipoles with the phosphorus-containing dipolarophiles and substituted ethylenes are examined.

A. K. Chandra; A. Michalak; M. T. Nguyen; R. F. Nalewajski

1998-01-01

74

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

NASA Astrophysics Data System (ADS)

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

Ghosh, Hirendra N.

2013-02-01

75

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

76

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

PubMed

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. PMID:20174482

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

2009-06-16

77

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. PMID:20174482

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

2010-01-01

78

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

PubMed

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

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

2015-03-01

79

Energy-sensitive X-ray radiography and charge sharing effect in pixelated detector  

NASA Astrophysics Data System (ADS)

The semiconductor pixel detector TimePix (256×256 pixels with a pitch of 55 ?m) is a newly developed successor of the Medipix2 device. Each Timepix pixel can be operated in Time-over-Threshold mode allowing direct energy measurement. The possibility of per pixel energy measurement presents a substantial advantage for X-ray radiography with polychromatic X-ray sources (tubes) allowing material identification (colour X-ray radiography) via analysis of transmission energy spectra. The energy resolution of the pixelated planar detector is, however, influenced by charge sharing. The ionization charge generated by the particle (X-ray photon) can be collected by several pixels, forming a cluster. If the fraction of the charge collected by a particular pixel drops below the energy threshold it is not counted and therefore it is lost. This fact, together with the presence of noise, limits the energy resolution of the device. A simplified model of the charge sharing effect is studied in this work and compared with experimental data. The application of a (per-pixel) energy-calibrated TimePix detector in the field of energy-sensitive X-ray radiography enables the recognition of soft biological materials (fat and muscle tissue) which is presented here.

Jakubek, Jan

2009-08-01

80

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

81

Development of a sensitive amplified luminescent proximity homogeneous assay to monitor the interactions between pTEFb and Tat.  

PubMed

The viral transactivator protein (Tat) plays an essential role in the replication of human immunodeficiency type 1 virus (HIV-1) by recruiting the host positive transcription elongation factor (pTEFb) to the RNA polymerase II transcription machinery to enable an efficient HIV-1 RNA elongation process. Blockade of the interaction between Tat and pTEFb represents a novel strategy for developing a new class of antiviral agents. In this study, we developed a homogeneous assay in AlphaLISA (amplified luminescent proximity homogeneous assay) format using His-tagged pTEFb and biotinylated Tat to monitor the interaction between Tat and pTEFb. On optimizing the assay conditions, the signal-to-background ratio was found to be greater than 10-fold. The assay was validated with untagged Tat and peptides known to compete with Tat for pTEFb binding. The Z' of the assay is greater than 0.5, indicating that the assay is robust and can be easily adapted to a high-throughput screening format. Furthermore, the affinity between Tat and pTEFb was determined to be approximately 20pM, and only 7% of purified Tat was found to be active in forming tertiary complex with pTEFb. Development of this assay should facilitate the discovery of a new class of antiviral agents providing HIV-1 patients with broader treatment choices. PMID:25132562

Burlein, Christine; Bahnck, Carolyn; Bhatt, Triveni; Murphy, Dennis; Lemaire, Peter; Carroll, Steve; Miller, Michael D; Lai, Ming-Tain

2014-08-14

82

Field-amplified sample injection coupled with pseudo-isotachophoresis technique for sensitive determination of selected psychiatric drugs in human urine samples after dispersive liquid-liquid microextraction.  

PubMed

A field-amplified sample injection (FASI) technique was elaborated for fast and sensitive determination of selected central nervous system drugs in human urine samples. Factors affecting the sensitivity enhancement, such as background electrolyte (BGE) and the analytical matrix composition were optimized and discussed. Pseudo-isotachophoresis (p-ITP) mechanism contribution in preconcentration mechanism was discussed. All separations were performed in uncoated fused silica capillaries 50 ?m × 57 cm at 22 kV. The optimized analytical matrix was composed of 0.25 mM HCOOH in 90% (v/v) methanol, while BGE contained 45 mM TRIS/HCl (pH 2.20). The head-column injection was performed in 0.25 mM HCOOH water solution (3s, 3.45 kPa). Sample was introduced into the capillary by electrokinetic injection (70 s, 5 kV) followed by short BGE plug (3s, 3.45 kPa). Seven psychiatric drugs (olanzapine, prochlorperazine dimaleate, trifluoperazine dihydrochloride, perphenazine, promazine hydrochloride, clomipramine hydrochloride, and chlorprothixene hydrochloride) were separated in about 6 min. The elaborated method was additionally supported with dispersive liquid-liquid microextraction (DLLME) technique which in summary with FASI provided about 8000-13,000-fold sensitivity enhancement in comparison to the capillary zone electrophoresis (CZE) method with standard hydrodynamic injection (5s, 3.45 kPa). PMID:24456599

Dziomba, Szymon; Kowalski, Piotr; S?omi?ska, Agata; B?czek, Tomasz

2014-02-01

83

Nanoparticle technology: amplifying the effective sensitivity of biomarker detection to create a urine test for hGH.  

PubMed

Several clinical-grade immunoassays exist for the specific measurement of hGH or its isoforms in blood but there is an urgent need to apply these same reliable assays to the measurement of hGH in urine as a preferred 'non-invasive' biofluid. Unfortunately, conventional hGH immunoassays cannot attain the sensitivity required to detect the low concentrations of hGH in urine. The lowest limit of sensitivity for existing hGH immunoassays is >50 pg/mL, while the estimated concentration of urinary hGH is about 1 pg/m-50 times lower than the sensitivity threshold. We have created novel N-isopropylacrylamide (NIPAm)-based hydrogel nanoparticles functionalized with an affinity bait. When introduced into an analyte-containing solution, the nanoparticles can perform, in one step, (1) complete harvesting of all solution phase target analytes, (2) full protection of the captured analyte from degradation and (3) sequestration of the analyte, effectively increasing the analyte concentration up to a hundredfold. N-isopropylacrylamide nanoparticles functionalized with Cibacron Blue F3GA bait have been applied to raise the concentration of urinary hGH into the linear range of clinical grade immunoassays. This technology now provides an opportunity to evaluate the concentration of hGH in urine with high precision and accuracy. PMID:20355230

Fredolini, Claudia; Tamburro, Davide; Gambara, Guido; Lepene, Benjamin S; Espina, Virginia; Petricoin, Emanuel F; Liotta, Lance A; Luchini, Alessandra

2009-09-01

84

Nanoparticle technology: Amplifying the effective sensitivity of biomarker detection to create a urine test for hGH  

PubMed Central

While several clinical grade immunoassays exist for the specific measurement of hGH, or its isoforms in blood, there is an urgent need to apply these same reliable assays to the measurement of hGH in urine as a preferred non invasive biofluid. Unfortunately, conventional hGH immunoassays can not attain the required sensitivity to detect the low concentrations of hGH in urine. The lowest limit of sensitivity for existing hGH immunoassays is >50 pg/mL, while the estimated concentration of urinary hGH is about one pg/mL: fifty times lower than the sensitivity threshold. We have created novel N-isopropylacrylamide (NIPAm) based hydrogel nanoparticles functionalized with an affinity bait. When introduced into an analyte containing solution, the nanoparticles can perform, in one step, in solution, a) complete harvesting of all solution phase target analytes, b) fully protect the captured analyte from degradation and c) sequester the analyte and effectively increase the analyte concentration up to 100 fold. NIPAm nanoparticles functionalized with Cibacron Blue F3GA bait have been applied to raise the concentration of urinary hGH into the linear range of clinical grade immunoassays. This technology now provides an opportunity to evaluate the concentration of hGH in urine with high precision and accuracy. PMID:20355230

Fredolini, Claudia; Tamburro, Davide; Gambara, Guido; Lepene, Ben; Espina, Virginia; Petricoin, Emanuel; Liotta, Lance A.; Luchini, Alessandra

2010-01-01

85

Switching Amplifiers  

NSDL National Science Digital Library

Created by Work-Ready Electronics, a project of the Advanced Technological Education, this module walks visitors through switching amplifiers. The site content is divided up into four sections: Switching Amplifiers Introduction, Class D Switching Amplifiers, Switching RF Power Amplifiers, and Troubleshooting. There is a quiz for each section to test what students learned in the module in the Knowledge Probe section, and the Learning Resources section contains four activities to help cement student understanding. There are also further resources - both print and Web based - for more information and two Questor games, a Flash quiz that reiterates the material covered. The Notebook function allows visitors to take notes and review them at any time. This is an excellent resource students and educators in electronics technician programs to introduce and explore switching amplifiers.

86

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

SciTech Connect

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

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

1999-08-18

87

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

88

Improved radiographic image amplifier panel  

NASA Technical Reports Server (NTRS)

Layered image amplifier for radiographic /X ray and gamma ray/ applications, combines very high radiation sensitivity with fast image buildup and erasure capabilities by adding a layer of material that is both photoconductive and light-emitting to basic image amplifier and cascading this assembly with a modified Thorne panel.

Brown, R. L., Sr.

1968-01-01

89

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

90

Charge behaviour and power consumption in ball mills: sensitivity to mill operating conditions, liner geometry and charge composition  

Microsoft Academic Search

Discrete element method (DEM) modelling has been used to systematically study the effects of changes in mill operating parameters and particle properties on the charge shape and power draw of a 5-m ball mill. Specifically, changes in charge fill level, lifter shape (either by design or wear) and lifter pattern are analysed. The effects of changes to the properties of

Paul W Cleary

2001-01-01

91

Extreme chemical sensitivity of nonlinear conductivity in charge-ordered LuFe2O4  

PubMed Central

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

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

2012-01-01

92

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

93

Bidirectional amplifier  

DOEpatents

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

Wright, James T. (Cedarcrest, NM)

1986-01-01

94

Ultrafast Charge Separation Dynamics of Twisted Intramolecular Charge Transfer State (TICT) in Coumarin Dye Sensitized TiO2 Film: A New Route to Achieve Higher Efficient Dye-Sensitized Solar Cell  

NASA Astrophysics Data System (ADS)

Ultrafast transient spectroscopy of 7-diethyl amino coumarin 3-carboxylic acid (D-1421) sensitized TiO2 film reveals that TICT states facilitate higher charge separation and slow recombination and proved to be new route to design higher efficient solar cell.

Verma, Sandeep; Ghosh, Hirendra N.

2013-03-01

95

Amplified Policymaking  

ERIC Educational Resources Information Center

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

Prince, Katherine; Woempner, Carolyn

2010-01-01

96

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

97

Trastuzumab increases the sensitivity of HER2-amplified human gastric cancer cells to oxaliplatin and cisplatin by affecting the expression of telomere-associated proteins  

PubMed Central

HER2 amplification occurs in ~20% of gastric cancer (GC) cases; however, in gastric and gastroesophageal junction cancer with HER2 gene amplification, trastuzumab in combination with cisplatin (DDP)-based chemotherapy has been reported to improve the oncological outcome. The aim of the present study was to evaluate the combined antitumor efficacy of trastuzumab and various platinum agents in GC cells and to elucidate mechanisms that may be involved in the interaction between trastuzumab and the platinum agents. The in vitro chemosensitivity of the GC cells to platinum agents was evaluated using the CellTiter 96® AQueous One Solution Cell Proliferation Assay kit. Treatment with 1.0?g/ml trastuzumab for 48 h significantly increased the sensitivity of NCI-N87 cells with HER2 amplification to oxaliplatin (Oxa) and DDP. This chemosensitivity was most prominent in the NCI-N87 cells, in which the half maximal inhibitory concentration of Oxa and DDP was decreased to ~3.29 and 6.91 times, respectively. The apoptotic effect of the platinum agents was evaluated by double-staining the GC cells with Annexin V-fluorescein isothiocyanate and propodium iodide. Consistent with the chemosensitivity analysis, apoptotic analysis indicated that trastuzumab significantly increased Oxa- and DDP-induced apoptosis in the NCI-N87 cells. Furthermore, the mRNA expression levels of various telomere-associated genes was determined by performing quantitative reverse transcription-polymerase chain reactions in a number of GC cell lines, and revealed that trastuzumab (alone and in combination with DDP) may downregulate the mRNA expression levels of the TPP1, TRF1, TRF2, TRF2IP and POT1 genes. However, western blot analysis demonstrated that trastuzumab (alone and in combination with DDP) may significantly downregulate the protein expression levels of telomeric repeat binding factor 2, protection of telomere 1 and TPP1 (formerly known as TINT1, PTOP and PIP). The results of the present study indicate a potential role of low-dose trastuzumab administration for increasing Oxa and DDP sensitivity in HER2-amplified GC cells, possibly via the downregulation of telomere-associated gene expression. PMID:25624920

LIU, YONGPING; LING, YANG; QI, QIUFENG; ZHU, MING; WAN, MEIZHEN; ZHANG, YAPING; ZHANG, CHANGSONG

2015-01-01

98

Net Positive Charge of HIV-1 CRF01_AE V3 Sequence Regulates Viral Sensitivity to Humoral Immunity  

PubMed Central

The third variable region (V3) of the human immunodeficiency virus type 1 (HIV-1) envelope gp120 subunit participates in determination of viral infection coreceptor tropism and host humoral immune responses. Positive charge of the V3 plays a key role in determining viral coreceptor tropism. Here, we examined by bioinformatics, experimental, and protein modelling approaches whether the net positive charge of V3 sequence regulates viral sensitivity to humoral immunity. We chose HIV-1 CRF01_AE strain as a model virus to address the question. Diversity analyses using CRF01_AE V3 sequences from 37 countries during 1984 and 2005 (n?=?1361) revealed that reduction in the V3's net positive charge makes V3 less variable due to limited positive selection. Consistently, neutralization assay using CRF01_AE V3 recombinant viruses (n?=?30) showed that the reduction in the V3's net positive charge rendered HIV-1 less sensitive to neutralization by the blood anti-V3 antibodies. The especially neutralization resistant V3 sequences were the particular subset of the CCR5-tropic V3 sequences with net positive charges of +2 to +4. Molecular dynamics simulation of the gp120 monomers showed that the V3's net positive charge regulates the V3 configuration. This and reported gp120 structural data predict a less-exposed V3 with a reduced net positive charge in the native gp120 trimer context. Taken together, these data suggest a key role of the V3's net positive charge in the immunological escape and coreceptor tropism evolution of HIV-1 CRF01_AE in vivo. The findings have molecular implications for the adaptive evolution and vaccine design of HIV-1. PMID:18787705

Shiino, Teiichiro; Suzuki, Takeyuki; Ishigatsubo, Yoshiaki; Ueda, Atsuhisa; Shirai, Akira; Takeno, Mitsuhiro; Hayakawa, Satoshi; Sato, Shigehiro; Tochikubo, Osamu; Kiyoura, Shingo; Sawada, Kaori; Ikegami, Takashi; Kanda, Tadahito; Kitamura, Katsuhiko; Sato, Hironori

2008-01-01

99

Gated charged-particle trap  

DOEpatents

The design and operation of a new type of charged-particle trap provides simultaneous measurements of mass, charge, and velocity of large electrospray ions. The trap consists of a detector tube mounted between two sets of center-bored trapping plates. Voltages applied to the trapping plates define symmetrically-opposing potential valleys which guide axially-injected ions to cycle back and forth through the charge-detection tube. A low noise charge-sensitive amplifier, connected to the tube, reproduces the image charge of individual ions as they pass through the detector tube. Ion mass is calculated from measurement of ion charge and velocity following each passage through the detector. 5 figs.

Benner, W.H.

1999-03-09

100

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

E-print Network

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

Oleg Meshcheryakov

2013-07-17

101

Magnetoelectric Sensors With Directly Integrated Charge Sensitive Readout Circuit—Improved Field Sensitivity and Signal-to-Noise Ratio  

Microsoft Academic Search

The large magnetoelectric (ME) coupling in the ME laminates makes them attractive for ultrasensitive room tempera- ture magnetic sensors. Here ,we investigate the field sensitivity and signal-to-noise ratio (SNR) of ME laminates, consisting of mag- netostrictive and piezoelectric layers (Metglas and piezopolymer PVDF were used as the model system), which are directly inte- grated with a low noise readout circuit.

Zhao Fang; Ninad Mokhariwale; Feng Li; Suman Datta; Q. M. Zhang

2011-01-01

102

Cryomicroscopy of radiation sensitive specimens on unmodified graphene sheets: reduction of electron-optical effects of charging.  

PubMed

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. PMID:23664842

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

2013-09-01

103

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. PMID:23664842

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

2013-01-01

104

LC/ESI-MS/MS detection of FAs by charge reversal derivatization with more than four orders of magnitude improvement in sensitivity[S  

PubMed Central

Quantitative analysis of fatty acids (FAs) is an important area of analytical biochemistry. Ultra high sensitivity FA analysis usually is done with gas chromatography of pentafluorobenzyl esters coupled to an electron-capture detector. With the popularity of electrospray ionization (ESI) mass spectrometers coupled to liquid chromatography, it would be convenient to develop a method for ultra high sensitivity FA detection using this equipment. Although FAs can be analyzed by ESI in negative ion mode, this method is not very sensitive. In this study, we demonstrate a new method of FA analysis based on conversion of the carboxylic acid to an amide bearing a permanent positive charge, N-(4-aminomethylphenyl)pyridinium (AMPP) combined with analysis on a reverse-phase liquid chromatography column coupled to an ESI mass spectrometer operating in positive ion mode. This leads to an ?60,000-fold increase in sensitivity compared with the same method carried out with underivatized FAs. The new method is about 10-fold more sensitive than the existing method of gas chromatography/electron-capture mass spectrometry of FA pentafluorobenzyl esters. Furthermore, significant fragmentation of the precursor ions in the nontag portion improves analytical specificity. We show that a large number of FA molecular species can be analyzed with this method in complex biological samples such as mouse serum. PMID:23945566

Bollinger, James G.; Rohan, Gajendra; Sadilek, Martin; Gelb, Michael H.

2013-01-01

105

STABILITY OF PULSES IN NONLINEAR OPTICAL FIBERS USING PHASESENSITIVE AMPLIFIERS  

E-print Network

STABILITY OF PULSES IN NONLINEAR OPTICAL FIBERS USING PHASE­SENSITIVE AMPLIFIERS J. NATHAN KUTZ y in nonlinear optical fibers with periodically­spaced phase­sensitive amplifiers, a situation where the averaged is carried out, and in the limit of small amplifier spacing, a steady­state pulse solution is shown

106

Optical Amplifiers for Telecommunications  

Microsoft Academic Search

This paper reviews optical amplifier technologies for telecommunications networks. The operation and applications of erbium doped fibre amplifiers (EDFAs), fibre Raman amplifiers (FRAs), erbium doped waveguide amplifiers (EDWAs) and semiconductor optical amplifiers (SOAs) are described. The factors that influence their gain, operating bandwidths, spectral profiles and noise are also discussed.

P. Urquhart; O. G. Lopez; G. Boyen; A. Bruckmann

2007-01-01

107

Highly sensitive detection of net hydrogen charged into austenitic stainless steel with secondary ion mass spectrometry.  

PubMed

Secondary ion mass spectrometry (SIMS) is used to detect local distributions of hydrogen in various materials. However, it has been well-known that it is extremely difficult to analyze net hydrogen (H(N)) in metals with SIMS. This was because hydrogen, which is originated from moisture (H(2)O), hydrocarbon (C(x)H(y)) or other organic materials (C(x)H(y)O(z)) existing on a sample surface or in the SIMS chamber, is simultaneously detected in the SIMS measurement of the H(N), and the H(N) and the background-originated hydrogen (H(BG)) cannot be distinguished in a SIMS profile. The effective method for reductions and determinations of the H(BG) in hydrogen measurements of metallic materials with the SIMS method has not been established. The present paper shows an effective method for reduction and estimation of H(BG) in SIMS analyses of hydrogen charged into type 316 L austenitic stainless steel, and an accurate estimation method of the net charged hydrogen. In this research, a silicon wafer is sputtered by a primary ion beam of a SIMS near an analyzed area (silicon sputtering method) to reduce H(BG). An uncharged type 316 L sample was prepared for estimation of H(BG) in SIMS measurements of the hydrogen-charged sample. The gross intensities of hydrogen between the hydrogen-charged sample and the uncharged sample were compared. The gross intensities of hydrogen of the uncharged sample (26.8-74.5 cps) were much lower than the minimal gross intensities of hydrogen of the hydrogen-charged sample (462-1140 cps). Thus, we could reduce the H(BG) enough to estimate the hydrogen charged into the type 316 L sample. Moreover, we developed a method to determine intensities of H(BG) in the measurement of the hydrogen-charged sample by estimating the time-variation of hydrogen intensities in the measurements of the uncharged sample. The intensities of the charged hydrogen can be obtained by subtracting the estimated intensities of the H(BG) from the gross intensities of hydrogen of the hydrogen-charged sample. The silicon sputtering method used to reduce H(BG) and the determination method for H(BG) in this research can be applied to the accurate hydrogen analysis for other various metallic materials. PMID:21401058

Awane, Tohru; Fukushima, Yoshihiro; Matsuo, Takashi; Matsuoka, Saburo; Murakami, Yukitaka; Miwa, Shiro

2011-04-01

108

Fluctuation dynamo amplified  

E-print Network

Fluctuation dynamo amplified by intermittent shear bursts J. Pratt The Fluctuation Dynamo Boussinesq MHD Convection Simulations Shear Bursts: Amplified Energy Production Magnetic Helicity Fluctuation dynamo amplified by intermittent shear bursts J. Pratt Thanks to my collaborators: A. Busse (U. Glasgow

109

Charge-sensitive vibrational modes in the (EDT-TTF-OX)2AsF6 chiral molecular conductors  

NASA Astrophysics Data System (ADS)

Infrared and Raman spectra of three chiral molecular conductors (EDT-TTF-OX)2AsF6, comprising of two salts based on enantiopure EDT-TTF-OX donor molecules and one based on their racemic mixture, have been measured as a function of temperature. In the frequency range of the C=C stretching vibrations of EDT-TTF-OX, charge-sensitive modes are identified based on theoretical calculations for neutral and oxidized EDT-TTF-OX using density functional theory (DFT) methods. The positions of C=C stretching modes in both Raman and infrared spectra of the (EDT-TTF-OX)2AsF6 materials are analyzed assuming a linear relationship between the frequency and charge of the molecule. The charge density on the EDTTTF-OX donor molecule is estimated to be +0.5 in all investigated materials and does not change with temperature. Therefore we suggest, that M-I transition observed in (EDT-TTF-OX)2AsF6 chiral molecular conductors at low temperature is not related to the charge ordering mechanism.

Olejniczak, Iwona; Fr?ckowiak, Arkadiusz; Matysiak, Jacek; Madalan, Augustin; Pop, Flavia; Avarvari, Narcis

2014-03-01

110

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

PubMed

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

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

2014-10-22

111

High dynamic range charge measurements  

DOEpatents

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

112

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. PMID:22514170

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

2012-01-01

113

An avenue of expanding triiodide reduction and shortening charge diffusion length in solid-state dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Enhancement in power conversion efficiency is a persistent pursuit for solid-state dye-sensitized solar cells (DSSCs). We report an experimental strategy of synthesizing I-/I3- doped 3-hydroxypropionitrile/polyaniline (HPN/PANi) solid electrolytes, aiming at expanding I3- reduction reaction from electrolyte/counter electrode interface to solid electrolyte system and shortening the charge diffusion path length. The DSSC with HPN/1.0 wt% PANi shows an efficiency of 3.70% in comparison to 1.49% from the cell with pristine HPN.

Li, Pinjiang; Duan, Yanyan; Tang, Qunwei; He, Benlin; Li, Ru

2015-01-01

114

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

115

Theoretical studies on effective metal-to-ligand charge transfer characteristics of novel ruthenium dyes for dye sensitized solar cells.  

PubMed

The development of ruthenium dye-sensitizers with highly effective metal-to-ligand charge transfer (MLCT) characteristics and narrowed transition energy gaps are essential for the new generation of dye-sensitized solar cells. Here, we designed a novel anchoring ligand by inserting the cyanovinyl-branches inside the anchoring ligands of selected highly efficient dye-sensitizers and studied their intrinsic optical properties using theoretical methods. Our calculated results show that the designed ruthenium dyes provide good performances as sensitizers compared to the selected efficient dyes, because of their red-shift in the UV-visible absorption spectra with an increase in the absorption intensity, smaller energy gaps and thereby enhancing MLCT transitions. We found that, the designed anchoring ligand acts as an efficient "electron-acceptor" which boosts electron-transfer from a -NCS ligand to this ligand via a Ru-bridge, thus providing a way to lower the transition energy gap and enhance the MLCT transitions. PMID:24743972

Wang, Huei-Tang; Taufany, Fadlilatul; Nachimuthu, Santhanamoorthi; Jiang, Jyh-Chiang

2014-05-01

116

Sensitivity and back-action in charge qubit measurements by a strongly coupled single-electron transistor  

E-print Network

We consider charge-qubit monitoring (continuous-in-time weak measurement) by a single-electron transistor (SET) operating in the sequential-tunneling regime. We show that commonly used master equations for this regime are not of the Lindblad form that is necessary and sufficient for guaranteeing valid physical states. In this paper we derive a Lindblad-form master equation and a corresponding quantum trajectory model for continuous measurement of the charge qubit by a SET. Our approach requires that the SET-qubit coupling be strong compared to the SET tunnelling rates. We present an analysis of the quality of the qubit measurement in this model (sensitivity versus back-action). Typically, the strong coupling when the SET island is occupied causes back-action on the qubit beyond the quantum back-action necessary for its sensitivity, and hence the conditioned qubit state is mixed. However, in one strongly coupled, asymmetric regime, the SET can approach the limit of an ideal detector with an almost pure conditioned state. We also quantify the quality of the SET using more traditional concepts such as the measurement time and decoherence time, which we have generalized so as to treat the strongly responding regime.

Neil P. Oxtoby; H. M. Wiseman; He-Bi Sun

2006-04-28

117

Optical amplifiers for telecommunications  

Microsoft Academic Search

The paper contains the results of simulation of Raman optical amplifiers with copropagating and counterpropagating pumping. The computer program was developed to calculate signals and noise of amplified spontaneous emission for various lengths of amplifier sections. The various applications of optical amplifiers allowing to increase regenerator section length are considered. The results of calculations are of interest to the designers

Maria S. Bylina; Sergey F. Glagolev

2008-01-01

118

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

PubMed

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

Marlow, Frank; Hullermann, Abigail; Messmer, Lisanne

2015-04-01

119

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

120

Amplified quantum transforms  

NASA Astrophysics Data System (ADS)

In this thesis we investigate two new Amplified Quantum Transforms. In particular we create and analyze the Amplified Quantum Fourier Transform (Amplified-QFT) and the Amplified-Haar Wavelet Transform. The Amplified-QFT algorithm is used to solve the Local Period Problem. We calculate the probabilities of success and compare this algorithm with the QFT and QHS algorithms. We also examine the Amplified-QFT algorithm for solving the Local Period Problem with Error Stream. We use the Amplified-Haar Wavelet Transform for solving the Local Constant or Balanced Signal Decision Problem which is a generalization of the Deutsch-Jozsa problem.

Cornwell, David J.

121

Instantaneous generation of charge-separated state on TiO? surface sensitized with plasmonic nanoparticles.  

PubMed

Photoexcitation of the plasmon band in metallic nanoparticles adsorbed on a TiO2 surface initiates many important photovoltaic and photocatalytic processes. The traditional view on the photoinduced charge separation involves excitation of a surface plasmon, its subsequent dephasing into electron-hole pairs, followed by electron transfer (ET) from the metal nanoparticle into TiO2. We use nonadiabatic molecular dynamics combined with time-domain density functional theory to demonstrate that an electron appears inside TiO2 immediately upon photoexcitation with a high probability (~50%), bypassing the intermediate step of electron-hole thermalization inside the nanoparticle. By providing a detailed, atomistic description of the charge separation, energy relaxation, and electron-hole recombination processes, the simulation rationalizes why the experimentally observed ultrafast photoinduced ET in an Au-TiO2 system is possible in spite of the fast energy relaxation. The simulation shows that the photogenerated plasmon is highly delocalized onto TiO2, and thus, it is shared by the electron donor and acceptor materials. In the 50% of the cases remaining after the instantaneous photogeneration of the charge-separated state, the electron injects into TiO2 on a sub-100 fs time scale by the nonadiabatic mechanism due to high density of acceptor states. The electron-phonon relaxation parallels the injection and is slower, resulting in a transient heating of the TiO2 surface by 40 K. Driven by entropy, the electron moves further into TiO2 bulk. If the electron remains trapped at the TiO2 surface, it recombines with the hole on a picosecond time scale. The obtained ET and recombination times are in excellent agreement with the experiment. The delocalized plasmon state observed in our study establishes a novel concept for plasmonic photosensitization of wide band gap semiconductors, leading to efficient conversion of photons to charge carriers and to hybrid materials with a wide variety of applications in photocatalysis and photovoltaics. PMID:24568726

Long, Run; Prezhdo, Oleg V

2014-03-19

122

Amplified OTDR Systems for Multipoint Corrosion Monitoring  

PubMed Central

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

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

2012-01-01

123

Phase-stable, microwave FEL amplifier  

SciTech Connect

Free-electron laser (FEL) amplifiers have demonstrated high efficiency and high output power for microwave wavelengths. However, using present technology, microwave FEL amplifiers are not phase stable enough to be suitable for driving linear accelerators, where several much amplifiers need to be phase locked. The growing wave`s phase sensitivity to the beam voltage in the small-signal gain regime is responsible for the largest contribution to this phase instability. We discuss a scheme that reduces the phase sensitivity to the beam voltage by operating off synchronism and matching the phase variation resulting from the desynchronism to the phase variation from the reduced plasma wavenumber as the beam voltage changes.

Carlsten, B.E.; Fazio, M.V.; Haynes, W.B.; May, L. [Los Alamos National Lab., NM (United States); Potter, M. [JP Accelerator Works, Inc., Los Alamos, NM (United States)

1995-07-01

124

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

PubMed

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

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

2013-08-21

125

REAP: Recycled Erbium Amplifier Pump  

NASA Astrophysics Data System (ADS)

We report a novel erbium doped fiber preamplifier design with a combination of high gain (greater than 40 dB) and low noise figure (3 dB) at 1556 nm for 80 mW of 980 nm pump power. The co-directional single pumped amplifier employs a composite two stage arrangement in which the second stage is pumped with recycled pump not used in the first stage. In addition, we contrast the amplifier performance trade-offs with the insertions of an isolator or a band pass filter or both in between the two amplifier sections. Finally, we demonstrate a receiver sensitivity of -37 dBm (156 photons/bit) with a 10 Gb/s optical preamplifier regenerator.

Delavaux, J.-M. P.; Nuyts, R. J.; Mizuhara, O.; Nagel, J. A.; Digiovanni, D. J.

1994-03-01

126

Holevo capacity of attenuation channels assisted by linear amplifiers  

SciTech Connect

We derive a capacity formula for attenuation channels assisted by quantum linear amplifiers when the input signal states are restricted to Gaussian states with the same correlation matrix. A phase insensitive linear amplifier and a phase sensitive linear amplifier are compared by using this formula.

Sohma, Masaki; Hirota, Osamu [Quantum Information Science Research Center, Tamagawa University Research Institute, Machida 194-8610 (Japan)

2007-08-15

127

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

2007-09-01

128

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

SciTech Connect

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

Zhao, Lihua, E-mail: lihua.zhao@ou.edu, E-mail: shi@ou.edu; Qiu, Jijun; Weng, Binbin; Chang, Caleb; Yuan, Zijian; Shi, Zhisheng, E-mail: lihua.zhao@ou.edu, E-mail: shi@ou.edu [School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019 (United States)

2014-02-28

129

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

130

Hybrid matrix amplifier  

SciTech Connect

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

131

Hybrid matrix amplifier  

SciTech Connect

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

132

Cross-differential amplifier  

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

133

Cross-differential amplifier  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

134

Cross-differential amplifier  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

135

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

136

Variation of stress with charging rate due to strain-rate sensitivity of silicon electrodes of Li-ion batteries  

NASA Astrophysics Data System (ADS)

Silicon is a promising anode material for lithium-ion batteries due to its enormous theoretical energy density. Fracture during electrochemical cycling has limited the practical viability of silicon electrodes, but recent studies indicate that fracture can be prevented by taking advantage of lithiation-induced plasticity. In this paper, we provide experimental insight into the nature of plasticity in amorphous LixSi thin films. To do so, we vary the rate of lithiation of amorphous silicon thin films and simultaneously measure stresses. An increase in the rate of lithiation results in a corresponding increase in the flow stress. These observations indicate that rate-sensitive plasticity occurs in a-LixSi electrodes at room temperature and at charging rates typically used in lithium-ion batteries. Using a simple mechanical model, we extract material parameters from our experiments, finding a good fit to a power law relationship between the plastic strain rate and the stress. These observations provide insight into the unusual ability of a-LixSi to flow plastically, but fracture in a brittle manner. Moreover, the results have direct ramifications concerning the rate-capabilities of silicon electrodes: faster charging rates (i.e., strain rates) result in larger stresses and hence larger driving forces for fracture.

Pharr, Matt; Suo, Zhigang; Vlassak, Joost J.

2014-12-01

137

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

138

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

139

Electronics Operational Amplifiers  

E-print Network

ECEN 325 Electronics Operational Amplifiers Dr. Aydin Ilker Kar¸silayan Texas A&M University Electronics - Aydin I. Kar¸silayan - Operational Amplifiers 1 #12;Equivalent CircuitEquivalent Circuit i=0 i=0 Electronics - Aydin I. Kar¸silayan - Operational Amplifiers 2 #12;vo vs. vdvo vs. vd Slope = A SAT vd vp vn

Palermo, Sam

140

Low noise tuned amplifier  

NASA Technical Reports Server (NTRS)

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. (inventor)

1984-01-01

141

Diode amplifier of modulated optical beam power  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

142

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

143

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

2013-11-21

144

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

PubMed

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

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

2015-01-14

145

Highly sensitive protein detection by combination of atomic force microscopy fishing with charge generation and mass spectrometry analysis.  

PubMed

An approach combining atomic force microscopy (AFM) fishing and mass spectrometry (MS) analysis to detect proteins at ultra-low concentrations is proposed. Fishing out protein molecules onto a highly oriented pyrolytic graphite surface coated with polytetrafluoroethylene film was carried out with and without application of an external electric field. After that they were visualized by AFM and identified by MS. It was found that injection of solution leads to charge generation in the solution, and an electric potential within the measuring cell is induced. It was demonstrated that without an external electric field in the rapid injection input of diluted protein solution the fishing is efficient, as opposed to slow fluid input. The high sensitivity of this method was demonstrated by detection of human serum albumin and human cytochrome b5 in 10(-17) -10(-18) m water solutions. It was shown that an external negative voltage applied to highly oriented pyrolytic graphite hinders the protein fishing. The efficiency of fishing with an external positive voltage was similar to that obtained without applying any voltage. PMID:25145394

Ivanov, Yuri D; Pleshakova, Tatyana; Malsagova, Krystina; Kozlov, Andrey; Kaysheva, Anna; Kopylov, Arthur; Izotov, Alexander; Andreeva, Elena; Kanashenko, Sergey; Usanov, Sergey; Archakov, Alexander

2014-10-01

146

Wireless Josephson amplifier  

SciTech Connect

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

Narla, A.; Sliwa, K. M.; Hatridge, M.; Shankar, S.; Frunzio, L.; Schoelkopf, R. J.; Devoret, M. H. [Department of Applied Physics, Yale University, New Haven, Connecticut 06511 (United States)

2014-06-09

147

A low noise FET with integrated charge restoration for radiation detectors  

Microsoft Academic Search

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

T. Nashoishibi; G. White

1990-01-01

148

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

PubMed

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

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

2015-05-10

149

10.0 Operational Amplifiers 1 of 25 Differential Amplifiers  

E-print Network

10.0 Operational Amplifiers 1 of 25 Differential Amplifiers #12;10.0 Operational Amplifiers 2 of 25 #12;10.0 Operational Amplifiers 3 of 25 Single Input ­ Single Output Gain Single Input ­ Differential Output Gain Difference Input ­ Dual Output Gain Common Mode Gain #12;10.0 Operational Amplifiers 4 of 25

Allen, Gale

150

Tanh cascode cell amplifier an arbitrary transfer characteristics amplifier  

E-print Network

Tanh cascode cell amplifier ­ an arbitrary transfer characteristics amplifier M. Ding and K.G. Gard An arbitrary transfer characteristic (TC) amplifier, called the tanh cascode cell (TCC) amplifier, is reported. This novel amplifier is capable of synthesising an arbitrary TC including the ideal rectifier transfer

151

LABORATORY 4 Amplifier Design Using Operational Amplifiers (OP-AMPs)  

E-print Network

ELEC 225 LABORATORY 4 Amplifier Design Using Operational Amplifiers (OP-AMPs) In ELEC 120, you designed circuits using the LM35 temperature sensor, DC fan, 741 operational amplifier, OPA 551 operational amplifier, and Light Emitting Diodes (LEDs). In this lab, we will focus on the design of an amplifier

Kozick, Richard J.

152

Linearly polarized fiber amplifier  

DOEpatents

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

Kliner, Dahv A.; Koplow, Jeffery P.

2004-11-30

153

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

154

A 2 to 26 GHz monolithic distributed amplifier  

NASA Astrophysics Data System (ADS)

A 2 to 26 GHz monolithic distributed amplifier for ECM and early warning EW receivers is presented. Without distributed amplifiers, the broadband mixers that are used to downconvert the RF signals to IF have high conversion loss, which limits the system sensitivity. Distributed amplifiers provide wideband amplification as well as lower noise figures, thereby maintaining receiver sensitivity over a wider frequency spectrum. A 2 to 26 GHz monolithic distributed amplifier is described. The amplifier is fabricated on MESFET and MODFET material. The measured noise figure (NF), gain and power output at 1 dB gain compression are compared for both types of materials. The objective of the design is to realize a manufacturable 2 to 26 GHz amplifier that meets the NF and gain requirements of a typical radar receiver system.

Bandla, S.; Spooner, F.; Tayrani, R.; Raffaelli, L.

1989-05-01

155

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

156

Theoretical investigation of the charge-transfer properties in different meso-linked zinc porphyrins for highly efficient dye-sensitized solar cells.  

PubMed

The charge transfer effect of different meso-substituted linkages on porphyrin analogue 1 (A1, B1 and C1) was theoretically investigated using density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. The calculated geometry parameters and natural bond orbital analysis reveal that the twisted conformation between porphyrin macrocycle and meso-substituted linkages leads to blocking of the conjugation of the conjugated backbone, and the frontier molecular orbital plot shows that the intramolecular charge transfer of A1, B1 and C1 hardly takes place. In an attempt to improve the photoinduced intramolecular charge transfer ability of the meso-linked zinc porphyrin sensitizer, a strong electron-withdrawing group (CN) was introduced into the anchoring group of analogue 1 forming analogue 2 (A2, B2 and C2). The density difference plot of A2, B2 and C2 shows that the charge transfer properties dramatically improved. The electron injection process has been performed using TDDFT; the direct charge-transfer transition in the A2-(TiO2)38 interacting system takes place; our results strongly indicated that introducing electron-withdrawing groups into the acceptor part of porphyrin dyes can fine-tune the effective conjugation length of the ?-spacer and improve intramolecular charge transfer properties, consequently inducing the electron injection process from the anchoring group of the porphyrin dye to the (TiO2)38 surface which may improve the conversion efficiency of the DSSCs. Our calculated results can provide valuable information and a promising outlook for computation-aided sensitizer design with anticipated good properties in further experimental synthesis. PMID:24810141

Namuangruk, Supawadee; Sirithip, Kanokkorn; Rattanatwan, Rattanawelee; Keawin, Tinnagon; Kungwan, Nawee; Sudyodsuk, Taweesak; Promarak, Vinich; Surakhot, Yaowarat; Jungsuttiwong, Siriporn

2014-06-28

157

Universal signal conditioning amplifier  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

158

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

159

Solid state radiographic image amplifiers, part C  

NASA Technical Reports Server (NTRS)

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

Szepesi, Z.

1971-01-01

160

Agilent 11982A Amplified Lightwave Converter  

E-print Network

Agilent 11982A Amplified Lightwave Converter Product Overview Wide bandwidth, sensitive O/E converter for characterizing lightwave systems and components Agilent's lightwave converter, the Agilent-end for lightwave frequency- and time- domain measurements. It can be used with Agilent spectrum analyzers

Park, Namkyoo

161

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

162

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

163

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

164

A grid amplifier  

Microsoft Academic Search

A 50-MESFET grid amplifier is reported that has a gain of 11 dB at 3.3 GHz. The grid isolates the input from the output by using vertical polarization for the input beam and horizontal polarization for the transmitted output beam. The grid unit cell is a two-MESFET differential amplifier. A simple calibration procedure allows the gain to be calculated from

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

1991-01-01

165

Organic Semiconductor Optical Amplifiers  

Microsoft Academic Search

Organic semiconducting materials have been researched for novel optoelectronic devices due to their efficient light emission and high gain properties. Such devices range from organic light-emitting diodes and solar cells to lasers and amplifiers. This paper explores the research carried out on one of these devices: organic semiconductor amplifiers that have shown to give high gains of 20-40 dB in

Dimali Amarasinghe; Arvydas Ruseckas; Graham A. Turnbull; Ifor D. W. Samuel

2009-01-01

166

EE 321 Amplifiers Fall 2008 Amplifiers, Biasing, and AC Coupling  

E-print Network

EE 321 Amplifiers Fall 2008 EE321 Lab Amplifiers, Biasing, and AC Coupling The purpose of this lab is to measure the characteristics of an amplifier, and to use the characteristics to add a bias circuit at the input. An amplifier can be represented in many different ways. Figure 1 shows a model for a voltage

Wedeward, Kevin

167

High stability amplifier  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

168

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

PubMed

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

Li, Huixing; Chen, Maodu

2013-12-01

169

Radiation and particle detector and amplifier  

NASA Technical Reports Server (NTRS)

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

Schmidt, K. C. (inventor)

1973-01-01

170

Electrospun amplified fiber optics.  

PubMed

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

Morello, Giovanni; Camposeo, Andrea; Moffa, Maria; Pisignano, Dario

2015-03-11

171

Electrospun Amplified Fiber Optics  

PubMed Central

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

2015-01-01

172

A grid amplifier  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

173

Universal signal conditioning amplifier  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

174

Charge transfer emission in coumarin 343 sensitized TiO{sub 2} nanoparticle: A direct measurement of back electron transfer  

SciTech Connect

Electron injection and back electron transfer dynamics in coumarin 343 (C-343) adsorbed on TiO{sub 2} nanoparticles are studied by picosecond transient absorption and time-resolved fluorescence spectroscopy. The direct detection of electrons in the nanoparticles and the parent cation are monitored using picosecond transient absorption spectroscopy, and the corresponding dynamics of the adsorbate are monitored by time-resolved absorption spectra of the cation radical of C-343 in the visible region. When the electron returns from the nanoparticles to the present cation, a low quantum yield red-shifted charge transfer emission is observed. Measuring the charge transfer emission lifetimes by a picosecond time-resolved fluorimeter, the author gets an exact rate of back electron transfer reaction from the nanoparticle to the parent cation.

Ghosh, H.N.

1999-11-25

175

Fourier plane image amplifier  

DOEpatents

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

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

1995-12-12

176

Fourier plane image amplifier  

DOEpatents

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

Hackel, Lloyd A. (Livermore, CA); Hermann, Mark R. (San Ramon, CA); Dane, C. Brent (Livermore, CA); Tiszauer, Detlev H. (Tracy, CA)

1995-01-01

177

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

178

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

PubMed

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

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

2014-10-01

179

Charge transport properties in TiO? network with different particle sizes for dye sensitized solar cells.  

PubMed

The charge transport properties in the TiO(2) nanoparticle networks with the different TiO(2) nanoparticle sizes were investigated by means of electrochemical impedance spectroscopy (EIS) with consideration of morphological aspects of mesoporous TiO(2) network including particle size (d(p)), coordination number (N(n)), neck diameter (d(n)), and effective surface area (S(e)). The morphological analysis of the network revealed that the particle size and surface area would be factors exerting an impact on the charge transport properties, while the coordination number and neck diameter seemed to be consistent with the nanoparticle size. As a result, the electron transport along with the TiO(2) network was predominantly affected by the particle size in terms of the mean free path; the bigger particle size provides both long travel distance and less collision chance with the boundary. Surface area seems to exert a strong influence on the recombination when it is in contact with an electrolyte, suggesting that pore size distribution determining penetration of an electrolyte has to be considered in terms of the effective surface area (S(e)). Due to the low transport resistance, high recombination resistance, and low chemical capacitance, the largest particle showed the longest diffusion length (L(n)). However, the highest efficiency observed in 15 nm TiO(2) nanoparticle photoanode indicated that the compensating characteristics of the morphological factors of the network for light harvesting efficiency (LHE) (surface area) and charge collection efficiency (?(c), particle size) should be balanced in designing a nanostructured network for high performance DSCs. PMID:23339618

Park, Kwangsuk; Zhang, Qifeng; Myers, Daniel; Cao, Guozhong

2013-02-01

180

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

181

Differential Amplifier for use with  

E-print Network

Differential Amplifier for use with Attenuated Probes Clint Sprott December 17, 1964 University of Wisconsin Thermonuclear Plasma Studies PLP 43 Copy No. 3, #12;Introduction: Differential Amplifier for use a factor of ten. Using the probe shown in Fig. 1 and the cathode follower amplifier circuit shown in Fig. 3

Sprott, Julien Clinton

182

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, Masanori; Miyachi, Takashi; Hattori, Maki; Sugita, Seiji; Takechi, Seiji; Okada, Nagaya

2013-03-01

183

Monolithic dye laser amplifier  

DOEpatents

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

Kuklo, T.C.

1993-03-30

184

Monolithic dye laser amplifier  

DOEpatents

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

Kuklo, Thomas C. (Ripon, CA)

1993-01-01

185

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

186

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

NASA Astrophysics Data System (ADS)

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

Velásquez, A. A.; Arroyave, M.

2014-01-01

187

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

Microsoft Academic Search

Efficient solar-driven catalytic water oxidation is one of the main challenges in solar-to-fuel conversion. In this proceeding, we investigate three approaches for constructing electron acceptor -sensitizer - catalysts systems for photocatalytic water oxidation and our current understanding of the relevant fundamental processes involved. We demonstrated that an all-inorganic molecular water oxidation catalyst (WOC), [{Ru4O4(OH)2(H2O)4}(gamma-SiW10O36)2]10- (or Ru4POM), catalyzed a homogenous O2

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

2011-01-01

188

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

NASA Technical Reports Server (NTRS)

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

Chen, C.-C.

1989-01-01

189

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

190

Strongly coupled, low noise DC-SQUID amplifiers  

Microsoft Academic Search

The dc Superconducting Quantum Interference Device (dc-SQUID) is one of the most sensitive magnetic\\u000afield sensors available. In this thesis we concentrate on its application as an amplifier. In this configuration,\\u000aan input circuit of interest can be connected by means of a coupling coil. The intended application of\\u000aour developed low-Tc SQUID amplifiers is the readout of the first

Johannes Pleikies

2009-01-01

191

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

NASA Astrophysics Data System (ADS)

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

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

2015-04-01

192

Rapid charge-transfer in polypyrrole-single wall carbon nanotube complex counter electrodes: Improved photovoltaic performances of dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cell (DSSC) is a promising solution to global energy and environmental problems because of its clean, high efficiency, good durability, and easy fabrication. However, enhancement of power conversion efficiency and high cost of Pt counter electrode are still significant issues in commercial application of DSSCs. Herein, pyrrole-single wall nanotube (pyrrole-SWCNT) complexes are pioneerly synthesized by a reflux technique and subsequently in-situ polymerized and employed as counter electrodes (CEs) for DSSCs. Different from traditional polypyrrole/SWCNT (PPy/SWCNT) composites, the resultant PPy-SWCNT complexes are expected to fulfill the good electrical-conduction of SWCNT and electrocatalytic behaviors of PPy in accelerating electrochemical activity and charge transfer owing to the covalent bond between PPy (N atoms) and SWCNT (C atoms). The DSSCs employing PPy-SWCNT complex CEs exhibit significantly enhanced photovoltaic performances, in which a promising power conversion efficiency of 8.30% is obtained from PPy-2 wt‰ SWCNT complex CE in comparison with 6.31% from PPy-only CE. The high conversion efficiency, rapid charge-transfer in combination with simple preparation, relatively low cost, and scalability demonstrates the potential use of PPy-SWCNT complexes in robust DSSCs.

He, Benlin; Tang, Qunwei; Luo, Jinghuan; Li, Qinghua; Chen, Xiaoxu; Cai, Hongyuan

2014-06-01

193

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

194

Sensitive low field Kerr electro-optic measurements in transformer oil  

Microsoft Academic Search

A frequency-selective amplifier was used to make sensitive Kerr electro-optic field mapping measurements with a small signal AC voltage superimposed on a DC level. With several different electrode materials, including brass, stainless steel, and aluminium, the authors have observed very significant levels of field distortion due to positive space charge on the order of 400 ?C\\/m3. It was possible to

D. Sheen; T. Fujiwara; M. Zahn

1988-01-01

195

Amplifying Electrochemical Indicators  

NASA Technical Reports Server (NTRS)

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

Fan, Wenhong; Li, Jun; Han, Jie

2004-01-01

196

Combination of a sub-3 ?m superficially porous particle packed column with charged aerosol detection for the simple and sensitive measurement of nine macrolides in human urine.  

PubMed

Due to the lack of chromophores in many macrolides, analytical methods based on mass spectrometry and electrochemical detection coupled to liquid chromatography have been suggested to be suitable for the quantification of macrolides in complex matrices. In this study, a simple and sensitive analytical method was established for the simultaneous measurement of nine macrolides in human urine by combining a sub-3 ?m superficially porous particle packed column with charged aerosol detection. After thorough investigation of various sample preparation methods, including two liquid-liquid extraction methods and four solid-phase extraction methods, HLB solid-phase extraction was selected and further optimized. Absolute recovery of the optimized sample preparation method ranged from 99.5-110.2%, indicating its very high extraction/clean-up efficiency. For chromatography, parameters influencing macrolide separation were systematically optimized, and the resulting conditions allowed baseline separation of nine macrolides within 24 min using a very simple mobile phase. The established method was validated for linearity, limit of detection, limit of quantification, absolute recovery, and precision. Based on its limit of detection (0.025-0.100 ?g/mL), the method had similar or greater sensitivity than most methods based on electrochemical detection. It was found that the current method was appropriate for application to real human urine samples after drug administration. PMID:25155847

Jia, Shaodong; Song, In Gi; Jeong, Kyung Min; Li, Jing; Park, Jeong Hill; Lee, Jeongmi; Kwon, Sung Won

2014-10-01

197

Heterogeneous synaptic covering and differential charge transfer sensitivity among the dendrites of a reconstructed abducens motor neurone: correlations between electron microscopic and computer simulation data.  

PubMed

Ultrastructural studies on the synaptology of dendritic arborizations of motoneurones have been problematic because dendrites are very thin in relation to their great length, and most of the studies on this topic have therefore dealt with only small parts of the dendritic tree. Here we compared the ultrastructural characteristics of the axon terminals distributed along the various dendrites of a single motoneurone. For this purpose, the light microscopic 3D reconstruction of the dendritic arborization of an intracellularly labelled abducens motoneurone was combined with an electron microscopic analysis of its synaptic contacts. Dendritic profiles were randomly sampled along the various dendrites and the axon terminals they received were classified on the basis of their ultrastructural features and their GABA-immunoreactivity. It emerged that the various dendrites differed according to the type and local arrangement of their synaptic inputs. Our second aim was to incorporate the morphological data obtained into a model giving the charge transfer effectiveness T(x) of the dendritic sites. The sensitivity S(x) of T(x) to changes in the membrane resistivity (Rm) simulating various levels of tonic synaptic activity was calculated. It turned out that both the proximal and distal regions of the dendritic arborization have a dense synaptic covering and a weak sensitivity to changes in the Rm, whereas the intermediate dendrites have a sparse synaptic covering and a high sensitivity to changes in tonic synaptic activity. This pattern of organisation might mediate the "gating" of a population of synapses covering some dendritic regions in a state-dependent fashion. PMID:14618098

Bras, Helene; Lahjouji, Fatiha; Korogod, Sergey M; Kulagina, Iryna B; Barbe, Annick

2003-01-01

198

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

199

Universal Signal Conditioning Amplifier  

NASA Technical Reports Server (NTRS)

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

Kinney, Frank

1997-01-01

200

Lightwave systems with optical amplifiers  

Microsoft Academic Search

Fiber-optic communication systems using semiconductor laser amplifiers are investigated theoretically and experimentally. The noise and bit-error-rate characteristics of lightwave systems with optical amplifiers are calculated and the dependence of system performance on amplifier characteristics such as optical bandwidth, noise figure, gain, etc., is shown. Experimental results for both a 4-Gb\\/s optical preamplifier as well as coherent and direct detection systems

N. A. Olsson

1989-01-01

201

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

202

Optical amplifier for space applications.  

PubMed

We describe an optical amplifier designed to amplify a spatially sampled component of an optical wavefront to kilowatt average power. The goal is means for implementing a strategy of spatially segmenting a large aperture wavefront, amplifying the individual segments, maintaining the phase coherence of the segments by active means, and imaging the resultant amplified coherent field. Applications of interest are the transmission of space solar power over multi-megameter distances, as to distant spacecraft, or to remote sites with no preexisting power grid. PMID:19401734

Fork, R L; Cole, S; Diffey, W; Gamble, L; Keys, A

1999-12-01

203

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

204

Optical Amplifier for Space Applications  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

205

Reflex ring laser amplifier system  

DOEpatents

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

Summers, Mark A. (Livermore, CA)

1985-01-01

206

3-D TiO2 nanoparticle/ITO nanowire nanocomposite antenna for efficient charge collection in solid state dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

TiO2 nanoparticle (NP)/ITO nanowire (NW) nanocomposites for use as photoelectrode materials were fabricated to improve the charge collection efficiency in solid state dye sensitized solar cells (ss-DSSCs). The average current density for ss-DSSCs containing TiO2 NP/ITO NW arrays was 7.2 mA cm-2 that was 98% higher than that for the conventional TiO2 NP ss-DSSCs. The intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) studies exhibited that the electron diffusion length of TiO2 NP/ITO-NW nanocomposite ss-DSSCs was in the range of 4.3-5.6 ?m, longer than that of TiO2 NP solar cells (2.6-4.1 ?m). The longer diffusion length was responsible for the boosted current densities of TiO2 NP/ITO NW nanocomposite ss-DSSCs. We also employed the TiO2 NP/ITO NW nanocomposite photoelectrode to inorganic-organic perovskite solar cells whose energy conversion efficiency was 7.5%.TiO2 nanoparticle (NP)/ITO nanowire (NW) nanocomposites for use as photoelectrode materials were fabricated to improve the charge collection efficiency in solid state dye sensitized solar cells (ss-DSSCs). The average current density for ss-DSSCs containing TiO2 NP/ITO NW arrays was 7.2 mA cm-2 that was 98% higher than that for the conventional TiO2 NP ss-DSSCs. The intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) studies exhibited that the electron diffusion length of TiO2 NP/ITO-NW nanocomposite ss-DSSCs was in the range of 4.3-5.6 ?m, longer than that of TiO2 NP solar cells (2.6-4.1 ?m). The longer diffusion length was responsible for the boosted current densities of TiO2 NP/ITO NW nanocomposite ss-DSSCs. We also employed the TiO2 NP/ITO NW nanocomposite photoelectrode to inorganic-organic perovskite solar cells whose energy conversion efficiency was 7.5%. Electronic supplementary information (ESI) available: SEM images of a 3-D TiO2 nanoparticle (NP)/ITO nanowire (NW) nanocomposite photoelectrode, photovoltaic properties, J-V curves for the best performance cells, and the plot of dye loading vs. active layer thickness. See DOI: 10.1039/c4nr00621f

Han, Gill Sang; Lee, Sangwook; Noh, Jun Hong; Chung, Hyun Suk; Park, Jong Hoon; Swain, Bhabani Sankar; Im, Jeong-Hyeok; Park, Nam-Gyu; Jung, Hyun Suk

2014-05-01

207

Self-amplifying mRNA vaccines.  

PubMed

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

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

2015-01-01

208

Multiwire dielectric detector for measuring the coordinates of charged particles  

SciTech Connect

An ionization-sensitive multiwire dielectric charged-particle detector (MDD) is described. The capability of recording the coordinates of 5.5 MeV alpha particles as well as Xe 132 ions with an energy of 1.1 MeV/nucleon was studied using a Xe 132 beam from the U-300 accelerator at JINR. The electronic system of the MDD includes a bipolar pulsed power supply block which enables operation of two MDDs simultaneously. Observations of the form of the signal from the MDD were performed with an amplifier and an S1-97 direct-gain oscillograph. A short-pulse former was developed to determine the characteristic temporal fluctuation of the signals from the amplifier.

Gasparyan, S.G.; Gukasyan, S.M.; Kavalov, R.L.; Papyan, G.A.; Parlakyan, L.K.; Chubaryan, G.G.

1988-05-01

209

Laser amplifier developments at Mercury  

SciTech Connect

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.

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

1993-09-01

210

2014 Amplifier -1 FREQUENCY RESPONSE OF  

E-print Network

2014 Amplifier - 1 FREQUENCY RESPONSE OF AN AUDIO AMPLIFIER The objectives of this experiment are amplifier · To thoroughly bore you APPARATUS: Audio Amplifier (Circuit Chip), Computer with FFTScope software, Speaker, Power supply, Interconnecting Cables good high fidelity amplifier will have frequency

Glashausser, Charles

211

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

2013-02-21

212

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

PubMed

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

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

2015-01-28

213

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

214

A MEMS-based precision operational amplifier  

E-print Network

Two main difficulties for amplifiers that attempt to make precision DC measurements are the inherent low-frequency noise of the amplifier and the leakage current of the amplifier input stage. This thesis presents a novel ...

Paik, Song-Hee Cindy, 1980-

2004-01-01

215

Microchannels as axonal amplifiers.  

PubMed

An implantable neural interface capable of reliable long-term high-resolution recording from peripheral nerves has yet to be developed. Device design is challenging because extracellular axonal signals are very small, decay rapidly with distance from the axon, and in myelinated fibres are concentrated close to nodes of Ranvier, which are around 1 mum long and spaced several hundred micrometers apart. We present a finite element model examining the electrical behavior of axons in microchannels, and demonstrate that confining axons in such channels substantially amplifies the extracellular signal. For example, housing a 10-microm myelinated axon in a 1-cm-long channel with a 1000-microm(2) cross section is predicted to generate a peak extracellular voltage of over 10 mV. Furthermore, there is little radial signal decay within the channel, and a smooth axial variation of signal amplitude along the channel, irrespective of node location. Additional benefits include a greater extracellular voltage generated by large myelinated fibres compared to small unmyelinated axons, and the reduction of gain to unity at the end of the channel which ensures that there can be no crosstalk with electrodes in other channels nearby. A microchannel architecture seems well suited to the requirements of a peripheral nerve interface. PMID:18334406

Fitzgerald, James J; Lacour, Stéphanie P; McMahon, Stephen B; Fawcett, James W

2008-03-01

216

Design and simulation of a gyroklystron amplifier  

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

217

A position sensitive microchannel photomultiplier for ultraviolet space astronomy  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

218

Broadband linear high-voltage amplifier for radio frequency ion traps.  

PubMed

We developed a linear high-voltage amplifier for small capacitive loads consisting of a high-voltage power supply and a transistor amplifier. With this cost-effective circuit including only standard parts sinusoidal signals with a few volts can be amplified to 1.7 kVpp over a usable frequency range at large-signal response spanning four orders of magnitude from 20 Hz to 100 kHz under a load of 10 pF. For smaller output voltages the maximum frequency shifts up to megahertz. We test different capacitive loads to probe the influence on the performance. The presented amplifier is sustained short-circuit proof on the output side, which is a significant advantage over other amplifier concepts. The amplifier can be used to drive radio frequency ion traps for single charged nano- and microparticles, which will be presented in brief. PMID:25430133

Kuhlicke, Alexander; Palis, Klaus; Benson, Oliver

2014-11-01

219

MOSFET's for Cryogenic Amplifiers  

NASA Technical Reports Server (NTRS)

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

Dehaye, R.; Ventrice, C. A.

1987-01-01

220

Roles of electrolytes on charge recombination in dye-sensitized TiO(2) solar cells (2): the case of solar cells using cobalt complex redox couples.  

PubMed

Dye-sensitized solar cells (DSC) were prepared from nanoporous TiO(2) electrodes with two different cobalt complex redox couples, propylene-1,2-bis(o-iminobenzylideneaminato)cobalt(II) {Co(II)(abpn)} and tris(4,4'-di-tert-buthyl-2,2'-bipyridine)cobalt(II) diperchlorate {Co(II)(dtb-bpy)(3)(ClO(4))(2)}. The performances of the DSCs were examined with varying the concentrations of the redox couples and Li cations in methoxyacetonitrile. Under 1 sun conditions, short-circuit currents (J(sc)) increased with the increase of the redox couple concentration, and the maximum J(sc) was found at the Li(+) concentration of 100 mM. To rationalize the observed trends of J(sc), electron diffusion coefficients and lifetimes in the DSCs were measured. Electron diffusion coefficients in the DSCs using cobalt complexes were comparable to the previously reported values of nanoporous TiO(2). Electron lifetime was independent of the concentration of the redox couples when the concentration ratio of Co(II)(L) and Co(III)(L) was fixed. With the increase of Li(+) concentration, the electron lifetime increased. These results were interpreted as due to their slow charge-transfer kinetics and the cationic nature of Co complex redox couples, in contrast to the anionic redox couple of I(-)/I(3)(-). The increase of the lifetimes with Li(+) was interpreted with the decrease of the local concentration of Co(III) near the surface of TiO(2). The addition of 4-tert-butylpyridine (tBP) with the presence of Li(+) increased J(sc) significantly. The observed increase of the electron lifetime by tBP could not explain the large increase of J(sc), implying that tBP facilitates the charge transfer from Co(II)(L) to dye cation, with the association of the change of the reorganization energy between Co(II) and Co(III). PMID:16851383

Nakade, Shogo; Makimoto, Yohei; Kubo, Wataru; Kitamura, Takayuki; Wada, Yuji; Yanagida, Shozo

2005-03-01

221

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

222

Active hair-bundle movements can amplify a hair cell's response to oscillatory mechanical stimuli  

E-print Network

Active hair-bundle movements can amplify a hair cell's response to oscillatory mechanical stimuli, 1999 To enhance their mechanical sensitivity and frequency selectivity, hair cells amplify the mechanical stimuli to which they respond. Although cell-body contractions of outer hair cells are thought

Hudspeth, A. James

223

Quantifying the effects of the cochlear amplifier on temporal and average-rate information in the  

E-print Network

Quantifying the effects of the cochlear amplifier on temporal and average-rate information-director, Harvard-M.I.T. Division of Health Sciences and Technology #12;Quantifying the effects of the cochlear to as the cochlear amplifier is believed to be responsible for sharp tuning and excellent sensitivity in the normal

Allen, Jont

224

Dispersive liquid-liquid microextraction prior to field-amplified sample injection for the sensitive analysis of 3,4-methylenedioxymethamphetamine, phencyclidine and lysergic acid diethylamide by capillary electrophoresis in human urine.  

PubMed

A novel capillary zone electrophoresis (CZE) with ultraviolet detection method has been developed and validated for the analysis of 3,4-methylenedioxymethamphetamine (MDMA), lysergic acid diethylamide (LSD) and phencyclidine (PCP) in human urine. The separation of these three analytes has been achieved in less than 8 min in a 72-cm effective length capillary with 50-?m internal diameter. 100 mM NaH(2)PO(4)/Na(2)HPO(4), pH 6.0 has been employed as running buffer, and the separation has been carried out at temperature and voltage of 20°C, and 25kV, respectively. The three drugs have been detected at 205 nm. Field amplified sample injection (FASI) has been employed for on-line sample preconcentration. FASI basically consists in a mismatch between the electric conductivity of the sample and that of the running buffer and it is achieved by electrokinetically injecting the sample diluted in a solvent of lower conductivity than that of the carrier electrolyte. Ultrapure water resulted to be the better sample solvent to reach the greatest enhancement factor. Injection voltage and time have been optimized to 5 kV and 20s, respectively. The irreproducibility associated to electrokinetic injection has been correcting by using tetracaine as internal standard. Dispersive liquid-liquid microextraction (DLLME) has been employed as sample treatment using experimental design and response surface methodology for the optimization of critical variables. Linear responses were found for MDMA, PCP and LSD in presence of urine matrix between 10.0 and 100 ng/mL approximately, and LODs of 1.00, 4.50, and 4.40 ng/mL were calculated for MDMA, PCP and LSD, respectively. The method has been successfully applied to the analysis of the three drugs of interest in human urine with satisfactory recovery percentages. PMID:23141624

Airado-Rodríguez, Diego; Cruces-Blanco, Carmen; García-Campaña, Ana M

2012-12-01

225

Power amplifier leads MMIC line  

NASA Astrophysics Data System (ADS)

The first commercial offerings of Texas Instrument GaAs monolithic microwave integrated circuits (MMICs) are noted, including three amplifiers in the TGA8000 line. Model TGA8014 is a power amplifier with two large FETs connected by an interstage matching network; it puts out at least 0.4 W of power per chip from 6 to 18 GHz. It achieves this power with 7-dB typical gain. Model TGA8021, a low-noise amplifier based on three 300-micron FETs, exhibits a noise figure of only 2.5 dB and more than 24-dB gain per chip from 9 to 10 GHz. Model TGA8035, a general-purpose driver amplifier, generates 16 mW (+12 dBm) of outer power from 6 to 16 GHz with 12-dB typical gain and 7-dB typical noise figure.

Nelson, Steve; Mitchell, Bill; Halladay, Ralph; Beall, John; Lehmann, Randy

1986-12-01

226

Design of micropower operational amplifiers  

E-print Network

The operational amplifier is a fundamental building block for electronic devices and systems. The advancement of modern electronic technology has been setting more performance demand on the underlying integrated circuits ...

Rayanakorn, Surapap

2006-01-01

227

Statistical Mechanics of Amplifying Apparatus  

E-print Network

We implement Feynman's suggestion that the only missing notion needed for the puzzle of Quantum Measurement is the statistical mechanics of amplifying apparatus. We define a thermodynamic limit of quantum amplifiers which is a classically describable system in the sense of Bohr, and define macroscopic pointer variables for the limit system. Then we derive the probabilities of Quantum Measurement from the deterministic Schroedinger equation by the usual techniques of Classical Statistical Mechanics.

Joseph Johnson

2005-02-08

228

Dye laser traveling wave amplifier  

NASA Technical Reports Server (NTRS)

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

Davidson, F.; Hohman, J.

1984-01-01

229

Measuring momentum for charged particle tomography  

DOEpatents

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

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

2010-11-23

230

Development of a low-noise amplifier for neutron detection in harsh environment  

NASA Astrophysics Data System (ADS)

A fast matching charge amplifier for neutron spectroscopy in harsh environment has been developed and tested at the JET Tokamak. This front-end circuit is capable to operate at a distance up to 100 meters from a sensor without increasing its equivalent noise charge. Further improvements are possible by exploiting the intrinsic performance of silicon-germanium bipolar junction transistors.

Angelone, M.; Cardarelli, R.; Paolozzi, L.; Pillon, M.

2014-10-01

231

Staggered Gain for 100+ GHz Broadband Amplifiers  

Microsoft Academic Search

A broadband amplifier is realized with cascaded stagger-tuned stages that are equalized for high bandwidth and low gain ripple. The staggered frequency response is demon- strated to improve the transimpedance limit of active circuits. The staggered response is demonstrated with a Darlington feed- back amplifier and a constructive wave amplifier, which achieves low group delay. The broadband amplifier is implemented

Joohwa Kim; James F. Buckwalter

2011-01-01

232

Four-Channel Differential AC Amplifier  

E-print Network

Four-Channel Differential AC Amplifier #12;INSTRUCTION MANUAL FOR HIGH-GAIN DIFFERENTIAL AMPLIFIER .......................................................................................................13 Each Differential AC Amplifier is delivered complete with: Four 3' Cables Rack Mount Hardware://www.a-msystems.com General Description Instrument Features The Four-Channel Differential AC Amplifier Model 1700 is designed

Kleinfeld, David

233

Handout 3 for EE-203 Differential Amplifiers  

E-print Network

Handout 3 for EE-203 Differential Amplifiers Sheikh Sharif Iqbal (Ref: Text book and KFUPM Online and applications associated with differential amplifiers. - Differential amplifier pair is a fundamental subcircuit used in the input stage of every operational amplifiers and many other linear integrated circuits

Iqbal, Sheikh Sharif

234

A Large Signal Theory or Traveling-Wave Amplifiers  

Microsoft Academic Search

The large-signal or nonlinear behavior of the traveling-wave amplifier is calculated in this paper by numerically integrating a set of equations of motion, which is essentially that of Nordsieck, but includes the space-charge repulsion between the electrons. The calculations were made assuming a loss-free circuit and a small coupling between the circuit and the beam. A method of computing the

P. K. Tien; L. R. Walker; V. M. Wolontis

1955-01-01

235

Nuclear magnetic resonance experiments with dc SQUID amplifiers  

SciTech Connect

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

Heaney, M.B. (California Univ., Berkeley, CA (USA). Dept. of Physics Lawrence Berkeley Lab., CA (USA))

1990-11-01

236

Rain Drop Charge Sensor  

NASA Astrophysics Data System (ADS)

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

S, Sreekanth T.

237

Optical amplifiers for coherent lidar  

NASA Technical Reports Server (NTRS)

We examine application of optical amplification to coherent lidar for the case of a weak return signal (a number of quanta of the return optical field close to unity). We consider the option that has been explored to date, namely, incorporation of an optical amplifier operated in a linear manner located after reception of the signal and immediately prior to heterodyning and photodetection. We also consider alternative strategies where the coherent interaction, the nonlinear processes, and the amplification are not necessarily constrained to occur in the manner investigated to date. We include the complications that occur because of mechanisms that occur at the level of a few, or one, quantum excitation. Two factors combine in the work to date that limit the value of the approach. These are: (1) the weak signal tends to require operation of the amplifier in the linear regime where the important advantages of nonlinear optical processing are not accessed, (2) the linear optical amplifier has a -3dB noise figure (SN(out)/SN(in)) that necessarily degrades the signal. Some improvement is gained because the gain provided by the optical amplifier can be used to overcome losses in the heterodyned process and photodetection. The result, however, is that introduction of an optical amplifier in a well optimized coherent lidar system results in, at best, a modest improvement in signal to noise. Some improvement may also be realized on incorporating more optical components in a coherent lidar system for purely practical reasons. For example, more compact, lighter weight, components, more robust alignment, or more rapid processing may be gained. We further find that there remain a number of potentially valuable, but unexplored options offered both by the rapidly expanding base of optical technology and the recent investigation of novel nonlinear coherent interference phenomena occurring at the single quantum excitation level. Key findings are: (1) insertion of linear optical amplifiers in well optimized conventional lidar systems offers modest improvements, at best, (2) the practical advantages of optical amplifiers, especially fiber amplifiers, such as ease of alignment, compactness, efficiency, lightweight, etc., warrant further investigation for coherent lidar, (3) the possibility of more fully optical lidar systems should be explored, (4) advantages gained by use of coherent interference of optical fields at the level of one, or a few, signal quanta should be explored, (5) amplification without inversion, population trapping, and use of electromagnetic induced transparency warrant investigation in connection with coherent lidar, (6) these new findings are probably more applicable to earth related NASA work, although applications to deep space should not be excluded, and (7) our own work in the Ultrafast Laboratory at UAH along some of the above lines of investigation, may be useful.

Fork, Richard

1996-01-01

238

Amplifier-Discriminator-Multiplexor card  

SciTech Connect

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

Graupman, D.

1986-02-01

239

Integrating and amplifying signal from riboswitch biosensors.  

PubMed

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

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

2015-01-01

240

Random Number Generation Using Amplified Spontaneous Emission in a Fiber Amplifier  

E-print Network

Random Number Generation Using Amplified Spontaneous Emission in a Fiber Amplifier Julia C. Salevan · Photon counting · Amplified spontaneous emission #12;System Er:Yb EDFA Bandpass Filter (FBG) ( 0 = 1552

Anlage, Steven

241

Isothermal amplified detection of DNA and RNA.  

PubMed

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

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

2014-05-01

242

Current vs. Voltage Feedback Amplifiers  

E-print Network

is a voltage source that is controlled by the potential difference between the two input terminals voltage to zero, hence the term voltage feedback. Gain Bandwidth Product Refer to the non-inverting gainCurrent vs. Voltage Feedback Amplifiers One question continuously troubles the analog design engi

Lanterman, Aaron

243

Raman amplifiers and fiber lasers  

Microsoft Academic Search

The summary form only given. Stimulated Raman scattering (SRS) is a process by which energy is transferred from one wavelength to the next through a nonlinear scattering process. This phenomenon can be used to Raman amplify signals in a telecommunication systems. In this tutorial, the process of SRS is reviewed; and the advantages of Raman pumping a transmission span, improved

C. Headley

2003-01-01

244

Dye laser traveling wave amplifier  

NASA Technical Reports Server (NTRS)

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

Davidson, F.

1983-01-01

245

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. PMID:15495423

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

2010-01-01

246

PASOTRON{trademark} amplifier experiments  

SciTech Connect

Preliminary experimental studies are reported of an L-Band amplifier based on Hughes` Plasma-Assisted, Slow-Wave Oscillator (PASOTRON) technology. The amplifier system utilizes a hollow-cathode-plasma electron-gun, and a plasma-filled Slow-Wave Structure (SWS) to produce {>=} 100-{micro}sec-long, 50 to 75-kV, 30 to 100-A electron-beam pulses that propagate in a plasma channel without the use of any externally applied axial magnetic field. The electron-beam pulse coincides with a 100-{micro}sec-long RF drive signal provided by a 2.6-kW TWT, which is coupled into the amplifier upstream of the SWS. The SWS consists of a ring-bar design which is novel to the PASOTRON family of devices and is used for its short length compared to a helix. Simulations on HP`s High Frequency Structure Simulator were used to optimize the ring-bar SWS. Preliminary data are reported showing the new L-Band amplifiers gain, power, efficiency, and bandwidth. Methods of eliminating a Backward Wave Oscillation (BWO), which was found to limit the performance of the tube, are also presented.

Ponti, E.S.; Goebel, D.M.; Feicht, J.R.; Santoru, J. [Hughes Research Labs., Malibu, CA (United States); Eisenhart, R.L. [Eisenhart (Robert L.), Woodland Hills, CA (United States)

1995-11-01

247

Gold Nanoparticle Labels Amplify Ellipsometric Signals  

NASA Technical Reports Server (NTRS)

The ellipsometric method reported in the immediately preceding article was developed in conjunction with a method of using gold nanoparticles as labels on biomolecules that one seeks to detect. The purpose of the labeling is to exploit the optical properties of the gold nanoparticles in order to amplify the measurable ellipsometric effects and thereby to enable ultrasensitive detection of the labeled biomolecules without need to develop more-complex ellipsometric instrumentation. The colorimetric, polarization, light-scattering, and other optical properties of nanoparticles depend on their sizes and shapes. In the present method, these size-and-shape-dependent properties are used to magnify the polarization of scattered light and the diattenuation and retardance of signals derived from ellipsometry. The size-and-shape-dependent optical properties of the nanoparticles make it possible to interrogate the nanoparticles by use of light of various wavelengths, as appropriate, to optimally detect particles of a specific type at high sensitivity. Hence, by incorporating gold nanoparticles bound to biomolecules as primary or secondary labels, the performance of ellipsometry as a means of detecting the biomolecules can be improved. The use of gold nanoparticles as labels in ellipsometry has been found to afford sensitivity that equals or exceeds the sensitivity achieved by use of fluorescence-based methods. Potential applications for ellipsometric detection of gold nanoparticle-labeled biomolecules include monitoring molecules of interest in biological samples, in-vitro diagnostics, process monitoring, general environmental monitoring, and detection of biohazards.

Venkatasubbarao, Srivatsa

2008-01-01

248

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

249

New architecture for RF power amplifier linearization  

E-print Network

Power amplifier linearization has become an important part of the transmitter system as 3G and developing 4G communication standards require higher linearity than ever before. The thesis proposes two power amplifier ...

Boo, Hyun H

2009-01-01

250

Uniplanar microwave balanced mixers and amplifiers  

E-print Network

The completely uniplanar broadband singly balanced diode mixers and FET amplifiers, which utilize coplanar waveguide and slot line as the main transmission lines, are presented. These mixers and amplifiers have several desirable features...

Hsu, Pang-Cheng

1995-01-01

251

Development of position sensitive radiation detectors using gas electron multipliers.  

PubMed

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

Park, Seongtae; Hahn, Chang Hie

2009-01-01

252

Solid state ku-band power amplifier  

NASA Technical Reports Server (NTRS)

The design, fabrication, and testing of two types of IMPATT diode reflection amplifiers and a transmission amplifier are given. The Ku-band IMPATT diode development is discussed. Circuitry and electrical performance of the final version of the Ku-band amplifier is described. Construction details and an outline and mounting drawing are presented.

Bowers, H. C.; Lockyear, W. H.

1972-01-01

253

Operational Amplifier Circuits ECE 2100 Circuit Analysis  

E-print Network

1 Operational Amplifier Circuits ECE 2100 Circuit Analysis updated 11 May 2012 Pre voltage source Vin assuming that the operational amplifier is not saturated (thus there is negative of this amplifier circuit? 2. Use your SPICE engine to plot Vout as a function of Vin as Vin is varied from -2V to 2

Miller, Damon A.

254

Remote Acquisition Amplifier For 50-Ohm Cable  

NASA Technical Reports Server (NTRS)

Buffer-amplifier unit designed to drive 50-Ohm cables up to 100 ft. (30 m) long, compensating for attenuation in cables and enabling remote operation of oscilloscopes. Variable resistor provides for adjustment of gain of amplifier, such that overall gain from input terminals of amplifier to output end of cable set to unity.

Amador, Jose J.

1995-01-01

255

High frequency, high voltage MOSFET isolation amplifier  

Microsoft Academic Search

The present invention utilizes a high voltage isolation amplifier as the drive means for the inductor of a programmable microwave attenuator. A pair of power MOSFET devices are used to control the current flow through a magnetic yoke. The power MOSPET devices cooperate with floating operational amplifier drive circuits to act as a transconductance amplifiers and pass a load current

1986-01-01

256

Efficient Amplifiers and Bounded Degree Optimization  

E-print Network

Efficient Amplifiers and Bounded Degree Optimization Piotr Berman \\Lambda Marek Karpinski y Abstract This paper studies the existence of efficient (small size) amplifiers for prov­ ing explicit an explicit construction for such amplifiers. We use this construction to improve the currently best known

Eckmiller, Rolf

257

NASA developments in solid state power amplifiers  

NASA Technical Reports Server (NTRS)

Over the last ten years, NASA has undertaken an extensive program aimed at development of solid state power amplifiers for space applications. Historically, the program may be divided into three phases. The first efforts were carried out in support of the advanced communications technology satellite (ACTS) program, which is developing an experimental version of a Ka-band commercial communications system. These first amplifiers attempted to use hybrid technology. The second phase was still targeted at ACTS frequencies, but concentrated on monolithic implementations, while the current, third phase, is a monolithic effort that focusses on frequencies appropriate for other NASA programs and stresses amplifier efficiency. The topics covered include: (1) 20 GHz hybrid amplifiers; (2) 20 GHz monolithic MESFET power amplifiers; (3) Texas Instruments' (TI) 20 GHz variable power amplifier; (4) TI 20 GHz high power amplifier; (5) high efficiency monolithic power amplifiers; (6) GHz high efficiency variable power amplifier; (7) TI 32 GHz monolithic power amplifier performance; (8) design goals for Hughes' 32 GHz variable power amplifier; and (9) performance goals for Hughes' pseudomorphic 60 GHz power amplifier.

Leonard, Regis F.

1990-01-01

258

Valves Based on Amplified Piezoelectric Actuators  

Microsoft Academic Search

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

R. Le Letty; N. Lhermet; G. Patient; F. Claeyssen; M. Lang

2004-01-01

259

Using Nondeterminism to Amplify Hardness Alexander Healy  

E-print Network

Using Nondeterminism to Amplify Hardness Alexander Healy Salil Vadhan Harvard University Emanuele Viola ABSTRACT We revisit the problem of hardness amplification in NP, as recently studied by O) , we amplify to hardness 1/2 - 1/n(1) . 2. If s(n) = 2n(1) , we amplify to hardness 1/2-1/2n(1) . 3

Viola, Emanuele

260

Random Number Generation Using Amplified Spontaneous Emission in a Fiber Amplifier  

E-print Network

. Results Yb/Er FA: Ytterbium/Erbium Fiber Amplifier BPF: Band Pass Filter EDFA: Erbium Doped FiberRandom Number Generation Using Amplified Spontaneous Emission in a Fiber Amplifier Julia C. Salevan spontaneous emission in a fiber amplifier as our random source. System Conclusions and Future Work Statistical

Anlage, Steven

261

High power gas laser amplifier  

DOEpatents

A high power output CO.sub.2 gas laser amplifier having a number of sections, each comprising a plurality of annular pumping chambers spaced around the circumference of a vacuum chamber containing a cold cathode, gridded electron gun. The electron beam from the electron gun ionizes the gas lasing medium in the sections. An input laser beam is split into a plurality of annular beams, each passing through the sections comprising one pumping chamber.

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

1981-01-01

262

High temperature current mirror amplifier  

DOEpatents

A high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg.

Patterson, III, Raymond B. (Melbourne, FL)

1984-05-22

263

High power regenerative laser amplifier  

DOEpatents

A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse. 7 figures.

Miller, J.L.; Hackel, L.A.; Dane, C.B.; Zapata, L.E.

1994-02-08

264

High power regenerative laser amplifier  

DOEpatents

A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse.

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

1994-01-01

265

Charge trapping correction in Ge spectrometers  

Microsoft Academic Search

In the present work, a charge trapping model is developed which does not require the assumption of shallow level detrapping. The model shows the charge trapping deficit to be proportional to S\\/sub o\\/t\\/sub coll\\/\\/sup N\\/, where S\\/sub o\\/ is the peak amplitude of the shaping amplifier pulse, t\\/sub coll\\/ is the charge collection time for the carrier being trapped, and

M. L. Simpson; T. W. Raudorf; T. J. Paulus; R. C. Trammell

1989-01-01

266

Log amplifier with pole-zero compensation  

DOEpatents

A logarithmic amplifier circuit provides pole-zero compensation for improved stability and response time over 6-8 decades of input signal frequency. The amplifier circuit includes a first operational amplifier with a first feedback loop which includes a second, inverting operational amplifier in a second feedback loop. The compensated output signal is provided by the second operational amplifier with the log elements, i.e., resistors, and the compensating capacitors in each of the feedback loops having equal values so that each break point or pole is offset by a compensating break point or zero.

Brookshier, William (Downers Grove, IL)

1987-01-01

267

Development of a HgCdTe photomixer and impedance matched GaAs FET amplifier  

NASA Technical Reports Server (NTRS)

A research program for the development of a 10.6 micron HgCdTe photodiode/GaAs field effect transistor amplifier package for use at cryogenic temperatures (77k). The photodiode/amplifier module achieved a noise equivalent power per unit bandwidth of 5.7 times 10 to the 20th power W/Hz at 2.0 GHz. The heterodyne sensitivity of the HgCdTe photodiode was improved by designing and building a low noise GaAs field effect transistor amplifier operating at 77K. The Johnson noise of the amplifier was reduced at 77K, and thus resulted in an increased photodiode heterodyne sensitivity.

Shanley, J. F.; Paulauskas, W. A.; Taylor, D. R.

1982-01-01

268

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

PubMed

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

Richter, Christoph; Beu, Max; Schlettwein, Derck

2015-01-21

269

Novel photoacid generators for chemically amplified resists  

NASA Astrophysics Data System (ADS)

Recently we have developed new class of non-ionic oxime sulfonate PAG. The compounds generate various kinds of sulfonic acids, such as n-propane, n-octane, camphor and p-toluene sulfonic acid under Deep-UV exposure and are applicable for chemically amplified (CA) photoresists. The application-relevant properties of the compounds such as solubility in propylene glycol monomethyl ether acetate (PGMEA), ethyl lactate, ethyl 3-ethoxypropionate, and 2-heptanone, UV absorption, thermal stability with or without poly(4-hydroxystyrene) (PHS), storage stability in a neat form or in PGMEA solution with or without additives, sensitivity in a model resist formulation, dissolution inhibition efficiency during the development process and volatility were evaluated. The compounds exhibit good solubility in PGMEA, high sensitivity in positive tone CA resist formulations, with Deep-UV exposure, and no significant volatility. Especially it was found that the compounds are superior in terms of thermal stability and storage stability, i.e., high thermal stability up to 188 degree(s)C in a phenolic matrix, and no change during storage in PGMEA at 60 degree(s)C for 5 months.

Yamato, Hitoshi; Asakura, Toshikage; Matsumoto, Akira; Ohwa, Masaki

2002-07-01

270

Real Time Monitoring of NH3 Concentration Using Diffusion Scrubber Sampling Technique and Result of Application to the Processing of Chemically Amplified Resists  

Microsoft Academic Search

The application of chemically amplified resist is known to cause a problem in the accurate measurement of the concentration of basic gas species ( NH3, N-methylpyrrolidone (NMP)) in a clean room environment because it is sensitive to its environment. Among various methods of measurement, diffusion scrubber sampling method was selected and tested. The environmental sensitivity of a commercial chemically amplified

Eunyoung Bae; Woosung Han; Youngbum Koh; Moonyoung Lee; Jonggil Lee

1995-01-01

271

Direct solar-pumped iodine laser amplifier  

NASA Technical Reports Server (NTRS)

This semiannual progress report covers the period from April 1, 1985 to Sept. 30, 1985 under NASA grant NAS1-441 entitled direct solar pumped iodine laser amplifier. During this period the parametric studies of the iodine laser oscillator pumped by a Vortek simulator was carried out before the amplifier studies. The amplifier studies are postponed to the extended period following completion of the parametric studies. In addition, the kinetic modeling of a solar pumped iodine laser amplifier, and the experimental work for a solar pumped dye laser amplifier are in progress. This report contains three parts: (1) the radiation characteristics of solar simulator and the parametric characteristics of photodissociation iodine laser continuously pumped by a Vortek solar simulator; (2) kinetic modeling of a solar pumped iodine laser amplifier; and (3) the study of the dye laser amplifier pumped by a Tamarack solar simulator.

Han, K. S.

1985-01-01

272

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

273

The spectacular human nose: an amplifier of individual quality?  

PubMed Central

Amplifiers are signals that improve the perception of underlying differences in quality. They are cost free and advantageous to high quality individuals, but disadvantageous to low quality individuals, as poor quality is easier perceived because of the amplifier. For an amplifier to evolve, the average fitness benefit to the high quality individuals should be higher than the average cost for the low quality individuals. The human nose is, compared to the nose of most other primates, extraordinary large, fragile and easily broken—especially in male–male interactions. May it have evolved as an amplifier among high quality individuals, allowing easy assessment of individual quality and influencing the perception of attractiveness? We tested the latter by manipulating the position of the nose tip or, as a control, the mouth in facial pictures and had the pictures rated for attractiveness. Our results show that facial attractiveness failed to be influenced by mouth manipulations. Yet, facial attractiveness increased when the nose tip was artificially centered according to other facial features. Conversely, attractiveness decreased when the nose tip was displaced away from its central position. Our results suggest that our evaluation of attractiveness is clearly sensitive to the centering of the nose tip, possibly because it affects our perception of the face’s symmetry and/or averageness. However, whether such centering is related to individual quality remains unclear. PMID:24765588

Mikalsen, ?se Kristine Rognmo; Yoccoz, Nigel Gilles; Laeng, Bruno

2014-01-01

274

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

275

A 2.5 Gb\\/s CMOS Burst-Mode Limiting Amplifier for GPON System  

Microsoft Academic Search

A 2.5Gb\\/s burst-mode limiting amplifier for gigabit passive optical networks (GPON) is presented in this paper. A multistage architecture with a feedforward automatic threshold control (ATC) circuit is used for quick response. A response time of 5ns and sensitivity of 4 mVpp1 is achieved by introducing a modified ATC circuit and a modified amplified stage with active feedback and negative

Chueh-hao Yu; Day-uei Li

2007-01-01

276

TA 7.4: A High-Swing 2V CMOSOperational Amplifier with Gain Enhancement usinga Replica Amplifier  

E-print Network

TA 7.4: A High-Swing 2V CMOSOperational Amplifier with Gain Enhancement usinga Replica Amplifier output resistance, butby matching main andreplica amplifiers, high effectiveopen-stageamplifiercircuitdemon- strates gain enhancementfor low-voltage applications. Consider a transconductance amplifier

Lee, Hae-Seung "Harry"

277

Amplified fragment length polymorphism versus random amplified polymorphic DNA markers: clonal diversity in Saxifraga cernua.  

PubMed

Random amplified polymorphic DNA (RAPD) markers are sensitive to changes in reaction conditions and may express polymorphisms of nongenetic origin. Taxa with variable chromosome numbers are particularly challenging cases, as differences in DNA content may also influence marker reproducibility. We addressed these problems by comparing RAPD and amplified fragment length polymorphism (AFLP) analyses of clonal identity and relationships in a chromosomally variable arctic plant, the polyploid Saxifraga cernua, which has been thought to be monoclonal over large geographical distances. Fifty-seven plants from four Greenland populations were analysed using a conservative scoring approach. In total, 26 AFLP and 32 RAPD multilocus phenotypes (putative clones) were identified, of which 21 were identical and each of the remaining five AFLP clones was split into two to three very similar RAPD clones. This minor difference can be explained by sampling error and stochastic variation. The pattern observed in Greenland corroborates our previous results from Svalbard, suggesting that rare sexual events in S. cernua are sufficient to maintain high levels of clonal diversity even at small spatial scales. We conclude that although AFLP analysis is superior in terms of efficiency, RAPDs may still be used as reliable markers in small low-tech laboratories. PMID:14653790

Kjølner, S; Såstad, S M; Taberlet, P; Brochmann, C

2004-01-01

278

Ultra low-noise charge coupled device  

NASA Technical Reports Server (NTRS)

Special purpose CCD designed for ultra low-noise imaging and spectroscopy applications that require subelectron read noise floors, wherein a non-destructive output circuit operating near its 1/f noise regime is clocked in a special manner to read a single pixel multiple times. Off-chip electronics average the multiple values, reducing the random noise by the square-root of the number of samples taken. Noise floors below 0.5 electrons rms are possible in this manner. In a preferred embodiment of the invention, a three-phase CCD horizontal register is used to bring a pixel charge packet to an input gate adjacent a floating gate amplifier. The charge is then repeatedly clocked back and forth between the input gate and the floating gate. Each time the charge is injected into the potential well of the floating gate, it is sensed non-destructively. The floating gate amplifier is provided with a reference voltage of a fixed value and a pre-charge gate for resetting the amplifier between charge samples to a constant gain. After the charge is repeatedly sampled a selected number of times, it is transferred by means of output gates, back into the horizontal register, where it is clocked in a conventional manner to a diffusion MOSFET amplifier. It can then be either sampled (destructively) one more time or otherwise discarded.

Janesick, James R. (Inventor)

1993-01-01

279

High temperature current mirror amplifier  

DOEpatents

Disclosed is a high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg. 2 figs.

Patterson, R.B. III.

1984-05-22

280

Sensitive and specific electrochemical sensors for charge-diffuse cations: use of lipophilic cyclodextrins and an enzyme relay for the determination of acetylcholine.  

PubMed

Lipophilic, alkylated cyclodextrins (CDs) are aromatic hosts which are excellent ionophores for reversibly binding size-matched, charge-diffuse cations. The application of lipophilic beta-CDs as ionophores for sensing acetylcholine chloride using a potentiometric ISE and an amperometric biosensor is described. Potentiometric ISEs, using 2,6-didodecyl-beta-CD as ionophore, showed a Nernstian response with a limit of detection -log[C] = 5.0 and selectivity coefficient -logKijPot = 4.2 (in serum levels of Na+, K+ and Ca2+). A Nernstian response is maintained in the presence of bovine serum albumin for a PVC- and a polyurethane-based electroactive membrane on initial contact. However, on prolonged contact, the polyurethane-based membranes showed a lower shift in Einitial0 (the bias potential on initial contact with analyte solution) than PVC. Amperometric biosensors were assembled by modifying screen-printed electrodes with a ferrocenyl charge shuttle, enzymes (horseradish peroxidase, choline oxidase and/or acetylcholine esterase) and a thin film comprising a polyurethane matrix, 2,3,6-triethyl-beta-CD, a plasticizer and a large anionic salt. The resulting sensor, which was capable of detecting subpicomolar levels of acetylcholine, was highly specific and was stable to storage in air and in solution. Interference from endogenous electroactive compounds was minimal. PMID:9008405

Kataky, R; Parker, D

1996-12-01

281

Multistaged stokes injected Raman capillary waveguide amplifier  

DOEpatents

A multistaged Stokes injected Raman capillary waveguide amplifier for providing a high gain Stokes output signal. The amplifier uses a plurality of optically coupled capillary waveguide amplifiers and one or more regenerative amplifiers to increase Stokes gain to a level sufficient for power amplification. Power amplification is provided by a multifocused Raman gain cell or a large diameter capillary waveguide. An external source of CO.sub.2 laser radiation can be injected into each of the capillary waveguide amplifier stages to increase Raman gain. Devices for injecting external sources of CO.sub.2 radiation include: dichroic mirrors, prisms, gratings and Ge Brewster plates. Alternatively, the CO.sub.2 input radiation to the first stage can be coupled and amplified between successive stages.

Kurnit, Norman A. (Santa Fe, NM)

1980-01-01

282

Particle-Charge Spectrometer  

NASA Technical Reports Server (NTRS)

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

Fuerstenau, Stephen; Wilson, Gregory R.

2008-01-01

283

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

284

Compact PIN-amplifier module for gigabit rates optical interconnection  

NASA Astrophysics Data System (ADS)

The extremely compact PIN-amplifier module (6mm X 6mm X 8. 23mm) consisting of an InGaAs photodiode and a GaAs preamplifier IC has been developed. The ceramic sub-carrier having a GaAs IC on the top and a photodiode on the side was hermetically sealed into a kovar package which is provided a glass window. The characteristics of this module the combination of a transimpedance amplifier IC (1. Ok2 load) and a photodiode with lOOpm6 photosensitive area demonstrated the bandwidth of 770MHz and the sensitivity of - 29. 3dBm (at 622Mbps) and -27. 6dBm (at 1. 0625Gbps).

Suzuki, Tomihiro; Mikamura, Yasuki; Murata, Kazuo; Sekiguchi, Takeshi; Shiga, Nobuo; Murakami, Yasunori

1991-04-01

285

1.3-um Raman fiber amplifier  

Microsoft Academic Search

The results of experimental research and numerical modeling of the 1.3 micrometers Raman fiber amplifier based on the high Gao2 doped fiber are presented. The Raman amplifier was pumped by the P2O5-doped fiber Raman laser. The measurements of gain and noise figure in broad range of experimental conditions are fulfilled. The amplifier gain coefficient was measured to be 42 dB\\/W.

Eugeni M. Dianov; I. A. Bufetov; Mikhail M. Bubnov; M. V. Grekov; Sergei A. Vasiliev; Oleg I. Medvedkov; A. V. Shubin; Alexei N. Guryanov; Vladimir F. Khopin; M. V. Yashkov; Evelyn M. DeLiso; D. L. Butler

2000-01-01

286

Fiber amplifiers for coherent space communication  

Microsoft Academic Search

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

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

2001-01-01

287

Square-Wave Analysis of Compensated Amplifiers  

Microsoft Academic Search

A complete analysis of a single-stage compensated video-frequency amplifier is presented. In this amplifier high-frequency compensation is obtained by the use of a shunt peaking coil in series with the plate load resistance, and low-frequency compensation is obtained by using a resistance-capacitance network in series with the plate load resistance. Both square-wave and sine-wave input voltages to the amplifier are

P. M. Seal

1949-01-01

288

Class E/F switching power amplifiers  

NASA Technical Reports Server (NTRS)

The present invention discloses a new family of switching amplifier classes called class E/F amplifiers. These amplifiers are generally characterized by their use of the zero-voltage-switching (ZVS) phase correction technique to eliminate of the loss normally associated with the inherent capacitance of the switching device as utilized in class-E amplifiers, together with a load network for improved voltage and current wave-shaping by presenting class-F.sup.-1 impedances at selected overtones and class-E impedances at the remaining overtones. The present invention discloses a several topologies and specific circuit implementations for achieving such performance.

Hajimiri, Seyed-Ali (Inventor); Aoki, Ichiro (Inventor); Rutledge, David B. (Inventor); Kee, Scott David (Inventor)

2004-01-01

289

Extensive reduction in back electron transfer in twisted intramolecular charge-transfer (TICT) coumarin-dye-sensitized TiO(2) nanoparticles/film: a femtosecond transient absorption study.  

PubMed

We report the synthesis, characterization, and optical and electrochemical properties of two structurally similar coumarin dyes (C1 and C2). These dyes have been deployed as sensitizers in TiO2 nanoparticles and thin films, and the effect of molecular structure on interfacial electron-transfer dynamics has been studied. Steady-state optical absorption, emission, and time-resolved emission studies on both C1 and C2, varying the polarity of the solvent and the solution pH, suggest that both photoexcited dyes exist in a locally excited (LE) state in solvents of low polarity. In highly polar solvents, however, C1 exists in an intramolecular charge-transfer (ICT) state, whereas C2 exists in both ICT and twisted intramolecular charge-transfer (TICT) states, their populations depending on the degree of polarity of the solvent and the pH of the solution. We have employed femtosecond transient absorption spectroscopy to monitor the charge-transfer dynamics in C1- and C2-sensitized TiO2 nanoparticles and thin films. Electron injection has been confirmed by direct detection of electrons in the conduction band of TiO2 nanoparticles and of radical cations of the dyes in the visible and near-IR regions of the transient absorption spectra. Electron injection in both the C1/TiO2 and C2/TiO2 systems has been found to be pulse-width limited (<100?fs); however, back-electron-transfer (BET) dynamics has been found to be slower in the C2/TiO2 system than in the C1/TiO2 system. The involvement of TICT states in C2 is solely responsible for the higher electron injection yield as well as the slower BET process compared to those in the C1/TiO2 system. Further pH-dependent experiments on C1- and C2-sensitized TiO2 thin films have corroborated the participation of the TICT state in the slower BET process in the C2/TiO2 system. PMID:24615725

Debnath, Tushar; Maity, Partha; Lobo, Hyacintha; Singh, Balvant; Shankarling, Ganapati S; Ghosh, Hirendra N

2014-03-17

290

Signal-Conditioning Amplifier Recorders  

NASA Technical Reports Server (NTRS)

Signal-conditioning amplifier recorders (SCAmpRs) have been proposed as a means of simplifying and upgrading the Kennedy Space Center (KSC) Ground Measurement System (GMS), which is a versatile data-acquisition system that gathers and records a variety of measurement data before and during the launch of a space shuttle. In the present version of the GMS system, signal conditioning amplifiers digitize and transmit data to a VME chassis that multiplexes up to 416 channels. The data is transmitted via a high-speed data bus to a second VME chassis where it is available for snapshots. The data is passed from the second VME chassis to a high-speed data recorder. This process is duplicated for installations at two launch pads and the Vehicle Assembly Building (VAB). Since any failure of equipment in the data path results in loss of data, much of the system is redundant. The architecture of the existing GMS limits expansion or any modification to the system to meet changing requirements because of the cost and time required. A SCAmpR-based system is much more flexible. The basis of the simplification, flexibility, and reliability is the shifting of the recording function to the individual amplifier channels. Each SCAmpR is a self-contained single channel data acquisition system, which in its current implementation, has a data storage capacity of up to 30 minutes when operating at the fastest data sampling rates. The SCAmpR channels are self-configuring and self-calibrating. Multiple SCAmpR channels are ganged on printed circuit boards and mounted in a chassis that provides power, a network hub, and Inter-Range Instrument Group (IRIG) time signals. The SCAmpR channels share nothing except physical mounting on a circuit board. All circuitry is electrically separate for each channel. All that is necessary to complete the data acquisition system is a single master computer tied to the SCAmpR channels by standard network equipment. The size of the data acquisition system dictates the requirements for the specific network equipment.

Medelius, Pedro J.; Taylor, John

2003-01-01

291

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

PubMed

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

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

2014-03-01

292

Amplified spontaneous emission and Rayleigh backscattering in strongly pumped fiber amplifiers  

Microsoft Academic Search

Amplified spontaneous emission (ASE) and Rayleigh backscattering (RBS) in strongly pumped fiber amplifiers are studied, employing a rate equation model. Approximate expressions for the ASE and RES, as well as for the amplifier noise figure are derived, based on approximate analytical expressions for the amplified signal, which are valid for both three-level and four-level systems. Numerical examples for rare-earth-doped fibers,

Amos A. Hardy; Ram Oron

1998-01-01

293

Resonant isolator for maser amplifier  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

294

Transverse pumped laser amplifier architecture  

DOEpatents

An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.

Bayramian, Andrew James; Manes, Kenneth; Deri, Robert; Erlandson, Al; Caird, John; Spaeth, Mary

2013-07-09

295

LASERS. AMPLIFIERS: Tunable dye laser amplifier chain for laser isotope separation  

Microsoft Academic Search

A tunable dye laser amplifier chain developed for experiments on atomic vapour laser isotope separation (AVLIS) is described. The system, pumped by copper vapour lasers, consists of a master oscillator and an amplifier stage including a preamplifier and three main amplifiers working in the saturation mode. The master oscillator of the stage is a dye laser with a grazing incidence

Igor'S. Grigoriev; Aleksei B. D'yachkov; Valerii P. Labozin; Sergei M. Mironov; Sergei A. Nikulin; Valerii A. Firsov

2004-01-01

296

Hidden Amplifier for a Galvanometer  

NASA Astrophysics Data System (ADS)

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

Weichman, Frank

2003-10-01

297

Quantum metrology with parametric amplifier-based photon correlation interferometers  

PubMed Central

Conventional interferometers usually utilize beam splitters for wave splitting and recombination. These interferometers are widely used for precision measurement. Their sensitivity for phase measurement is limited by the shot noise, which can be suppressed with squeezed states of light. Here we study a new type of interferometer in which the beam splitting and recombination elements are parametric amplifiers. We observe an improvement of 4.1±0.3?dB in signal-to-noise ratio compared with a conventional interferometer under the same operating condition, which is a 1.6-fold enhancement in rms phase measurement sensitivity beyond the shot noise limit. The improvement is due to signal enhancement. Combined with the squeezed state technique for shot noise suppression, this interferometer promises further improvement in sensitivity. Furthermore, because nonlinear processes are involved in this interferometer, we can couple a variety of different waves and form new types of hybrid interferometers, opening a door for many applications in metrology. PMID:24476950

Hudelist, F.; Kong, Jia; Liu, Cunjin; Jing, Jietai; Ou, Z.Y.; Zhang, Weiping

2014-01-01

298

Label-free electrical quantification of amplified nucleic acids through nanofluidic diodes.  

PubMed

A label-free method of quantifying nucleic acids in polymerase chain reaction (PCR) is described and could be the basis for miniaturized devices that can amplify and detect target nucleic acids in real time. The method takes advantage of ionic current rectification effect discovered in nanofluidic channels exhibiting a broken symmetry in electrochemical potential - nanofluidic diodes. Nanofluidic diodes are prototyped here on nanopipettes readily pulled from individual thin-walled glass capillaries for a proof of concept demonstration yet the basic concept would be applicable to ionic rectifiers constructed through other means. When a nanopipette modified in the tip region with cationic polyelectrolytes is presented with an unpurified PCR product, the tip surface electrostatically interacts with the amplicons and modulates its ionic rectification direction in response to the intrinsic charge of those adsorbed. Modulations are gradual and correlate well with the mass concentration of the amplicons above 2.5 ng/?L, rather than their sizes, with adequate discrimination against the background. Moreover, the tip surface, following a measurement, is regenerated through a layer-by-layer assembly of cationic polyelectrolytes and amplicons. The regenerated tips are capable of measuring distinct mass concentrations without signs of noticeable degradation in sensitivity. Further, the tips are shown capable of reproducing the amplification curve of real-time PCR through sequential steps of surface regeneration and simple electrical readout during the intermediate reaction stages. This suggests that nanopipettes as nanofluidic diodes are at a capacity to be employed for monitoring the PCR progress. PMID:23835221

Liu, Yifan; Yobas, Levent

2013-12-15

299

Progress on diamond amplified photo-cathode  

Microsoft Academic Search

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,

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

2011-01-01

300

Integrated-circuit balanced parametric amplifier  

NASA Technical Reports Server (NTRS)

Amplifier, fabricated on single dielectric substrate, has pair of Schottky barrier varactor diodes mounted on single semiconductor chip. Circuit includes microstrip transmission line and slot line section to conduct signals. Main features of amplifier are reduced noise output and low production cost.

Dickens, L. E.

1975-01-01

301

Method for reducing snap in magnetic amplifiers  

NASA Technical Reports Server (NTRS)

Method of reducing snap in magnetic amplifiers uses a degenerative feedback circuit consisting of a resistor and a separate winding on a magnetic core. The feedback circuit extends amplifier range by allowing it to be used at lower values of output current.

Fischer, R. L. E.; Word, J. L.

1968-01-01

302

Using Nondeterminism to Amplify Hardness Alexander Healy  

E-print Network

Using Nondeterminism to Amplify Hardness Alexander Healy Salil Vadhan Division of Engineering revisit the problem of hardness amplification in NP, as recently studied by O'Donnell (JCSS `04). We prove to compute f on a 1/2 - 1/s (n) fraction of inputs. In particular, 1. If s(n) = n(1) , we amplify to hardness

Viola, Emanuele

303

Using Nondeterminism to Amplify Hardness Alexander Healy  

E-print Network

Using Nondeterminism to Amplify Hardness Alexander Healy Salil Vadhan Division of Engineering revisit the problem of hardness amplification in NP, as recently studied by O'Donnell (STOC `02). We prove to compute f on a 1/2 - 1/s (n) fraction of inputs. In particular, 1. If s(n) = n(1) , we amplify to hardness

Vadhan, Salil

304

Design of a 250 GHz gyrotron amplifier  

E-print Network

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

Nanni, Emilio A. (Emilio Alessandro)

2010-01-01

305

Experiment 1 A MOSFET Differential Amplifier  

E-print Network

1 EE100B Experiment 1 A MOSFET Differential Amplifier College of Engineering University of California, Riverside Objective To explore the use of MOSFETs, analog differential amplifiers and current as the current source, all implemented using MOSFETs. Equipment 2 MOSFET Arrays (MC14007UB), 5 10k resistors

Fonoberov, Vladimir

306

Power amplifier for ultrasonic transducer excitation  

Microsoft Academic Search

Design of the power amplifier for ultrasonic transducer excitation is presented. We assumed that the amplifier output impedance will be significantly lower than the transducer input impedance. Therefore we suggest to used the transformer as voltage step-up and impedance matching element. The transformer influence on the ultrasonic transducer bandwidth and the power transfer efficiency are analyzed using the Butterworth-Van Dyke

L. Svilainis

307

Diamond Amplified Photocathodes John Smedley1  

E-print Network

Diamond Amplified Photocathodes John Smedley1 , Ilan Ben-Zvi1 , Jen Bohon2 , Xiangyun Chang1 protecting the cathode from the accelerator. The amplifier is a thin diamond wafer which converts energetic. The electrons drift through the diamond under an external bias and are emitted into vacuum via a hydrogen

308

Thermoacoustic Stirling Engine --An acoustic amplifier  

E-print Network

Thermoacoustic Stirling Engine -- An acoustic amplifier: ambient heat exchanger (water) stacked screen regenerator hot heat exchanger10 kW sound 2 kW electricity 12 kW sound 10 kW sound 10 kW sound 12 amplifier: ambient heat exchanger (air) stacked screen regenerator hot heat exchanger thermosiphons

Lee, Dongwon

309

Effects Of Environmental Electrical Charges On Spacecraft  

NASA Technical Reports Server (NTRS)

Handbook presents information on three kinds of disruptive effects of environmental electrical charges upon operations of electronic circuits and other sensitive equipment in spacecraft. Addresses surface and internal charging and discharging, single-event upsets, and related design issues.

Robinson, Paul A., Jr.

1993-01-01

310

Neodymium, erbium, and ytterbium co-doped fiber amplifier  

Microsoft Academic Search

A combination of erbium (Er), ytterbium (Yb), and neodymium (Nd), in fiber amplifiers, is examined. This combination extends the pumping wavelength spectrum by creating a new pumping path. Furthermore, the Nd addition enables pumping the amplifier from within the amplifier center, and thereby decreases the amplified spontaneous emission at the amplifier ends. A mathematical model is presented relating the excited

Itai Ron; Amos A. Hardy

2011-01-01

311

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

312

Design and performance of the beamlet amplifiers  

SciTech Connect

In future laser systems, such as the National Ignition Facility (NIF), multi-segment amplifiers (MSAs) will be used to amplify the laser beam to the required levels. As a prototype of such a laser architecture, the authors have designed, built, and tested flash-lamp-pumped, Nd:Glass, Brewster-angle slab MSAs for the Beamlet project. In this article, they review the fundamentals of Nd:Glass amplifiers, describe the MSA geometry, discuss parameters that are important in amplifier design, and present our results on the characterization of the Beamlet MSAs. In particular, gain and beam steering measurements show that the Beamlet amplifiers meet all optical performance specifications and perform close to model predictions.

Erlandson, A.C.; Rotter, M.D.; Frank, M.D.; McCracken, R.W.

1996-06-01

313

Direct solar-pumped iodine laser amplifier  

NASA Technical Reports Server (NTRS)

During this period the parametric studies of the iodine laser oscillator pumped by a Vortek simulator were carried out before amplifier studies. The amplifier studies are postponed to the extended period after completing the parametric studies. In addition, the kinetic modeling of a solar-pumped iodine laser amplifier, and the experimental work for a solar pumped dye laser amplifier are in progress. This report contains three parts: (1) a 10 W CW iodine laser pumped by a Vortek solar simulator; (2) kinetic modeling to predict the time to lasing threshold, lasing time, and energy output of solar-pumped iodine laser; and (3) the study of the dye laser amplifier pumped by a Tamarack solar simulator.

Han, K. S.

1986-01-01

314

Capability of charge signal conversion and transmission by water chains confined inside Y-shaped carbon nanotubes  

NASA Astrophysics Data System (ADS)

The molecular scale signal conversion, transmission, and amplification by a single external charge through a water-mediated Y-shaped nanotube have been studied using molecular dynamics simulations. Our results show that the signal converting capability is highly sensitive to the magnitude of the charge, while the signal transmitting capability is independent of the charge signal. There is a sharp two-state-like transition in the signal converting capacity for both positive and negative charges. When the charge magnitude is above a threshold (|q| ? ˜0.7 e), the water dipole orientations in the main tube can be effectively controlled by the signaling charge (i.e., signal conversion), and then be transmitted and amplified through the Y-junction, despite the thermal noises and interferences between branch signals. On the other hand, the signal transmitting capability, characterized by the correlation between the two water dipole orientations in the two branches, is found to be always larger than 0.6, independent of charge signals, indicating that the water-mediated Y-tube is an excellent signal transmitter. These findings may provide useful insights for the future design of molecular scale signal processing devices based on Y-shaped nanotubes.

Tu, Yusong; Lu, Hangjun; Zhang, Yuanzhao; Huynh, Tien; Zhou, Ruhong

2013-01-01

315

SQUID amplifiers for infrared detectors and other applications  

SciTech Connect

The advantages of superconducting processing circuitry for focal plane arrays include low power consumption and the possibility of integrating processing circuitry and detectors on the same substrate. The latter configuration allows for reduction in the number of leads to the readout system and therefore removes a significant bottle neck to processing the massive quantities of data coming from large IR FPAs. All signal processing steps may be executed with superconducting circuit elements. Amplification in superconducting circuitry is performed with the SQUID (Superconducting Quantum Interference Device) amplifier. The present phase I SBIR is being used to investigate a scheme for multiplexing many inputs into one SQUID amplifier. This will reduce the number of SQUID amplifiers needed which is a significant improvement because typical high-gain, multiturn-input SQUIDs are the largest element of superconductivity circuitry. The anticipated payoff of this research is in shrinking the size needed for superconducting circuitry that will be integrated onto IR FPA's. In addition, this method should add very little or no noise to the intrinsic detector noise, thus avoiding any degradation in sensitivity when individual detectors are integrated into the array.

Osterman, D.

1990-12-14

316

Fiber optical parametric amplifiers in optical communication systems  

PubMed Central

The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time-division multiplexed formats. High-quality mid-span spectral inversion has been demonstrated at 0.64 Tb/s, avoiding electronic dispersion compensation. All-optical amplitude regeneration of amplitude-modulated signals has been performed, while PSAs have been used to demonstrate phase regeneration of phase-modulated signals. A PSA with 1.1-dB noise figure has been demonstrated, and preliminary wavelength-division multiplexing experiments have been performed with PSAs. 512 Gb/s have been transmitted over 6,000 km by periodic phase conjugation. Simulations indicate that PIAs could reach data rate x reach products in excess of 14,000 Tb/s × km in realistic wavelength-division multiplexed long-haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long-haul communication networks are discussed. PMID:25866588

Marhic (†), Michel E; Andrekson, Peter A; Petropoulos, Periklis; Radic, Stojan; Peucheret, Christophe; Jazayerifar, Mahmoud

2015-01-01

317

Identification of druggable cancer driver genes amplified across TCGA datasets.  

PubMed

The Cancer Genome Atlas (TCGA) projects have advanced our understanding of the driver mutations, genetic backgrounds, and key pathways activated across cancer types. Analysis of TCGA datasets have mostly focused on somatic mutations and translocations, with less emphasis placed on gene amplifications. Here we describe a bioinformatics screening strategy to identify putative cancer driver genes amplified across TCGA datasets. We carried out GISTIC2 analysis of TCGA datasets spanning 16 cancer subtypes and identified 486 genes that were amplified in two or more datasets. The list was narrowed to 75 cancer-associated genes with potential "druggable" properties. The majority of the genes were localized to 14 amplicons spread across the genome. To identify potential cancer driver genes, we analyzed gene copy number and mRNA expression data from individual patient samples and identified 42 putative cancer driver genes linked to diverse oncogenic processes. Oncogenic activity was further validated by siRNA/shRNA knockdown and by referencing the Project Achilles datasets. The amplified genes represented a number of gene families, including epigenetic regulators, cell cycle-associated genes, DNA damage response/repair genes, metabolic regulators, and genes linked to the Wnt, Notch, Hedgehog, JAK/STAT, NF-KB and MAPK signaling pathways. Among the 42 putative driver genes were known driver genes, such as EGFR, ERBB2 and PIK3CA. Wild-type KRAS was amplified in several cancer types, and KRAS-amplified cancer cell lines were most sensitive to KRAS shRNA, suggesting that KRAS amplification was an independent oncogenic event. A number of MAP kinase adapters were co-amplified with their receptor tyrosine kinases, such as the FGFR adapter FRS2 and the EGFR family adapters GRB2 and GRB7. The ubiquitin-like ligase DCUN1D1 and the histone methyltransferase NSD3 were also identified as novel putative cancer driver genes. We discuss the patient tailoring implications for existing cancer drug targets and we further discuss potential novel opportunities for drug discovery efforts. PMID:24874471

Chen, Ying; McGee, Jeremy; Chen, Xianming; Doman, Thompson N; Gong, Xueqian; Zhang, Youyan; Hamm, Nicole; Ma, Xiwen; Higgs, Richard E; Bhagwat, Shripad V; Buchanan, Sean; Peng, Sheng-Bin; Staschke, Kirk A; Yadav, Vipin; Yue, Yong; Kouros-Mehr, Hosein

2014-01-01

318

Identification of Druggable Cancer Driver Genes Amplified across TCGA Datasets  

PubMed Central

The Cancer Genome Atlas (TCGA) projects have advanced our understanding of the driver mutations, genetic backgrounds, and key pathways activated across cancer types. Analysis of TCGA datasets have mostly focused on somatic mutations and translocations, with less emphasis placed on gene amplifications. Here we describe a bioinformatics screening strategy to identify putative cancer driver genes amplified across TCGA datasets. We carried out GISTIC2 analysis of TCGA datasets spanning 14 cancer subtypes and identified 461 genes that were amplified in two or more datasets. The list was narrowed to 73 cancer-associated genes with potential “druggable” properties. The majority of the genes were localized to 14 amplicons spread across the genome. To identify potential cancer driver genes, we analyzed gene copy number and mRNA expression data from individual patient samples and identified 40 putative cancer driver genes linked to diverse oncogenic processes. Oncogenic activity was further validated by siRNA/shRNA knockdown and by referencing the Project Achilles datasets. The amplified genes represented a number of gene families, including epigenetic regulators, cell cycle-associated genes, DNA damage response/repair genes, metabolic regulators, and genes linked to the Wnt, Notch, Hedgehog, JAK/STAT, NF-KB and MAPK signaling pathways. Among the 40 putative driver genes were known driver genes, such as EGFR, ERBB2 and PIK3CA. Wild-type KRAS was amplified in several cancer types, and KRAS-amplified cancer cell lines were most sensitive to KRAS shRNA, suggesting that KRAS amplification was an independent oncogenic event. A number of MAP kinase adapters were co-amplified with their receptor tyrosine kinases, such as the FGFR adapter FRS2 and the EGFR family adapter GRB7. The ubiquitin-like ligase DCUN1D1 and the histone methyltransferase NSD3 were also identified as novel putative cancer driver genes. We discuss the patient tailoring implications for existing cancer drug targets and we further discuss potential novel opportunities for drug discovery efforts. PMID:24874471

Chen, Ying; McGee, Jeremy; Chen, Xianming; Doman, Thompson N.; Gong, Xueqian; Zhang, Youyan; Hamm, Nicole; Ma, Xiwen; Higgs, Richard E.; Bhagwat, Shripad V.; Buchanan, Sean; Peng, Sheng-Bin; Staschke, Kirk A.; Yadav, Vipin; Yue, Yong; Kouros-Mehr, Hosein

2014-01-01

319

Cascaded transformerless DC-DC voltage amplifier with optically isolated switching devices  

NASA Technical Reports Server (NTRS)

A very high voltage amplifier is provided in which plural cascaded banks of capacitors are switched by optically isolated control switches so as to be charged in parallel from the preceding stage or capacitor bank and to discharge in series to the succeeding stage or capacitor bank in alternating control cycles. The optically isolated control switches are controlled by a logic controller whose power supply is virtually immune to interference from the very high voltage output of the amplifier by the optical isolation provided by the switches, so that a very high voltage amplification ratio may be attained using many capacitor banks in cascade.

Sridharan, Govind (inventor)

1993-01-01

320

Techniques for high-efficiency outphasing power amplifiers  

E-print Network

A trade-off between linearity and efficiency exists in conventional power amplifiers (PAs). The outphase amplifying concept overcomes this trade-off by enabling the use of high efficiency, non-linear power amplifiers for ...

Godoy, Philip (Philip Andrew)

2011-01-01

321

Ph 315 Lab Notes A. La Rosa OPERATIONAL AMPLIFIERS  

E-print Network

Ph 315 Lab Notes A. La Rosa OPERATIONAL AMPLIFIERS ___________________________________________________________ 1. THE ROLE OF OPERATIONAL AMPLIFIERS A typical digital data acquisition system uses a transducer or microcontroller (volts). A conditioning circuit composed of operational amplifiers is then use for that purpose

322

PH-315 Lab Notes A. La Rosa OPERATIONAL AMPLIFIERS  

E-print Network

PH-315 Lab Notes A. La Rosa OPERATIONAL AMPLIFIERS ___________________________________________________________ 1. THE ROLE OF OPERATIONAL AMPLIFIERS A typical digital data acquisition system uses a transducer or microcontroller (volts). A conditioning circuit composed of operational amplifiers is then use for that purpose

La Rosa, Andres H.

323

Galen Sasaki University of Hawaii 1 Optical Amplifiers  

E-print Network

1 Galen Sasaki University of Hawaii 1 Components · Optical Amplifiers ­ Semiconductor Optical Amplifiers (SOAs) · Transmitters ­ Lasers ­ External Cavity Lasers ­ Tunable Lasers ­ Vertical Cavity Surface Emitting Lasers ­ LEDs Galen Sasaki University of Hawaii 2 Outline · Optical Amplifiers ­ Semiconductor

Sasaki, Galen H.

324

Neodymium, erbium, and ytterbium co-doped fiber amplifier  

NASA Astrophysics Data System (ADS)

A combination of erbium (Er), ytterbium (Yb), and neodymium (Nd), in fiber amplifiers, is examined. This combination extends the pumping wavelength spectrum by creating a new pumping path. Furthermore, the Nd addition enables pumping the amplifier from within the amplifier center, and thereby decreases the amplified spontaneous emission at the amplifier ends. A mathematical model is presented relating the excited population density, the signal power along the amplifier, the energy transfer among the ions, and the amplified spontaneous emissions. The study compares the amplifier characteristics of Er-Yb-Nd co-doped amplifier with a traditional Er-Yb amplifier for various combinations. The new configuration adds flexibility into the amplifier design. By properly selecting its parameters, one can increase the output signal power and decrease the amplified spontaneous emission, to comply with various requirements.

Ron, Itai; Hardy, Amos A.

2011-07-01

325

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

2012-03-01

326

Multi-pass light amplifier  

NASA Technical Reports Server (NTRS)

A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A confocal resonator or White Cell resonator is provided, including two or three curvilinearly shaped mirrors facing each other along a resonator axis and an optical gain medium positioned on the resonator axis between the mirrors (confocal resonator) or adjacent to one of the mirrors (White Cell). In a first embodiment, two mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator. The optical gain medium may be solid-state, liquid or gaseous medium and may be pumped longitudinally or transversely. In a second embodiment, first and second mirrors face a third mirror in a White Cell configuration, and the optical gain medium is positioned at or adjacent to one of the mirrors. Defocusing means and optical gain medium cooling means are optionally provided with either embodiment, to controllably defocus the light beam, to cool the optical gain medium and to suppress thermal lensing in the gain medium.

Plaessmann, Henry (Inventor); Grossman, William M. (Inventor)

1997-01-01

327

Single mode terahertz quantum cascade amplifier  

NASA Astrophysics Data System (ADS)

A terahertz (THz) optical amplifier based on a 2.9 THz quantum cascade laser (QCL) structure has been demonstrated. By depositing an antireflective coating on the QCL facet, the laser mirror losses are enhanced to fully suppress the lasing action, creating a THz quantum cascade (QC) amplifier. Terahertz radiation amplification has been obtained, by coupling a separate multi-mode THz QCL of the same active region design to the QC amplifier. A bare cavity gain is achieved and shows excellent agreement with the lasing spectrum from the original QCL without the antireflective coating. Furthermore, a maximum optical gain of ˜30 dB with single-mode radiation output is demonstrated.

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

2014-10-01

328

Phase noise in RF and microwave amplifiers.  

PubMed

Understanding amplifier phase noise is a critical issue in many fields of engineering and physics, such as oscillators, frequency synthesis, telecommunication, radar, and spectroscopy; in the emerging domain of microwave photonics; and in exotic fields, such as radio astronomy, particle accelerators, etc. Focusing on the two main types of base noise in amplifiers, white and flicker, the power spectral density of the random phase ?(t) is S?(f) = b(0) + b(-1)/f. White phase noise results from adding white noise to the RF spectrum in the carrier region. For a given RF noise level, b(0) is proportional to the reciprocal of the carrier power P(0). By contrast, flicker results from a near-dc 1/f noise-present in all electronic devices-which modulates the carrier through some parametric effect in the semiconductor. Thus, b(-1) is a parameter of the amplifier, constant in a wide range of P(0). The consequences are the following: Connecting m equal amplifiers in parallel, b(-1) is 1/m times that of one device. Cascading m equal amplifiers, b(-1) is m times that of one amplifier. Recirculating the signal in an amplifier so that the gain increases by a power of m (a factor of m in decibels) as a result of positive feedback (regeneration), we find that b(-1) is m(2) times that of the amplifier alone. The feedforward amplifier exhibits extremely low b(-1) because the carrier is ideally nulled at the input of its internal error amplifier. Starting with an extensive review of the literature, this article introduces a system-oriented model which describes the phase flickering. Several amplifier architectures (cascaded, parallel, etc.) are analyzed systematically, deriving the phase noise from the general model. There follow numerous measurements of amplifiers using different technologies, including some old samples, and in a wide frequency range (HF to microwaves), which validate the theory. In turn, theory and results provide design guidelines and give suggestions for CAD and simulation. To conclude, this article is intended as a tutorial, a review, and a systematic treatise on the subject, supported by extensive experiments. PMID:23221210

Boudot, Rodolphe; Rubiola, Enrico

2012-12-01

329

Electrochemical sensing of DNA hybridization based on duplex-specific charge compensation.  

PubMed

A nonlabeling voltammetric detection method for DNA hybridization has been developed, in which [Fe(CN)(6)](3-) in solution can readily approach an electrode surface covered with a charge-compensated DNA duplex layer and thus provides a strong redox-sensing current. Charge compensation for negative charges on the DNA backbone has been specifically accomplished on DNA duplexes by discouraging nonspecific binding of positively charged intercalating molecules with single strands. A pretreatment of DNA-modified electrodes with sodium dodecyl sulfate before the intercalator binding process is essential in preventing the nonspecific binding. Since ferricyanide, the only electrochemically active species, is present in the voltammetric solution, the detection signal can be amplified by increasing its concentration. Combination of the duplex-specific charge compensation with the signal amplification has achieved a remarkable signal difference: in 30 mM [Fe(CN)(6)](3-), the area ratio between cyclic voltammograms of the hybridized and unhybridized electrodes is approximately 200 when 3,6-diaminoacridine is used as the intercalator. High sensitivity of the method has been demonstrated by detecting 10 fM (100 zmol in amount) of a target probe DNA. PMID:14961719

Park, Nokyoung; Hahn, Jong Hoon

2004-02-15

330

Improved detection of alkaloids in crude extracts applying capillary electrophoresis with field amplified sample injection  

Microsoft Academic Search

A simple and effective method for the sensitive detection of alkaloids in crude plant extracts applying capillary electrophoresis with field amplified sample injection (FASI) is described. This method was compared with normal pressure injection for the determination of alkaloids in methanolic extracts from roots of Berberis vulgaris L. (Berberidaceae) and Hydrastis canadensis L. (Ranunculaceae) using a 1:1 mixture of 200

Matthias Unger; Joachim Stöckigt

1997-01-01

331

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

332

Near-infrared thermal lens spectrometer based on an erbium-doped fiber amplifier and  

E-print Network

Near-infrared thermal lens spectrometer based on an erbium-doped fiber amplifier and an acousto. Tran A novel spectrometer that is based on the use of the thermal lens effect for sensitive be developed. The thermal lens technique is one such possibility. The thermal lens technique is based

Reid, Scott A.

333

Investigation of coherent amplification with a semiconductor optical amplifier employed in a swept source OCT system  

Microsoft Academic Search

Optical coherence tomography relies on the coherent gating and coherent amplification from its reference light to produce high axial resolution, high sensitivity image. The signal to noise ratio of the optical coherence tomography image is proportional to the detected back-scattering photon numbers from sample beam. Thus, the gain of an optical amplifier device can be added to the weak sample

Bin Rao; Jun Zhang; Qiang Wang; Zhongping Chen

2007-01-01

334

Current pulse amplifier transmits detector signals with minimum distortion and attenuation  

NASA Technical Reports Server (NTRS)

Amplifier translates the square pulses generated by a boron-trifluoride neutron sensitive detector located adjacent to a nuclear reactor to slower, long exponential decay pulses. These pulses are transmitted over long coaxial cables with minimum distortion and loss of frequency.

Bush, N. E.

1967-01-01

335

Event-driven charge-coupled device design and applications therefor  

NASA Technical Reports Server (NTRS)

An event-driven X-ray CCD imager device uses a floating-gate amplifier or other non-destructive readout device to non-destructively sense a charge level in a charge packet associated with a pixel. The output of the floating-gate amplifier is used to identify each pixel that has a charge level above a predetermined threshold. If the charge level is above a predetermined threshold the charge in the triggering charge packet and in the charge packets from neighboring pixels need to be measured accurately. A charge delay register is included in the event-driven X-ray CCD imager device to enable recovery of the charge packets from neighboring pixels for accurate measurement. When a charge packet reaches the end of the charge delay register, control logic either dumps the charge packet, or steers the charge packet to a charge FIFO to preserve it if the charge packet is determined to be a packet that needs accurate measurement. A floating-diffusion amplifier or other low-noise output stage device, which converts charge level to a voltage level with high precision, provides final measurement of the charge packets. The voltage level is eventually digitized by a high linearity ADC.

Doty, John P. (Inventor); Ricker, Jr., George R. (Inventor); Burke, Barry E. (Inventor); Prigozhin, Gregory Y. (Inventor)

2005-01-01

336

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,

337

Development of a Broadband NbTiN Traveling Wave Parametric Amplifier for MKID Readout  

NASA Astrophysics Data System (ADS)

The sensitivity of microwave kinetic inductance detectors (MKIDs) using dissipation readout is limited by the noise temperature of the cryogenic amplifier, usually a HEMT with 5 K. A lower noise amplifier is required to improve NEP and reach the photon noise limit at millimeter wavelengths. Eom et al. have proposed a kinetic inductance traveling wave (KIT) parametric amplifier (also called the dispersion-engineered travelling wave kinetic inductance parametric amplifier) that utilizes the nonlinearity with very low dissipation of NbTiN. This amplifier has the promise to achieve quantum limited noise, broad bandwidth, and high dynamic range, all of which are required for ideal MKID dissipation readout. We have designed a KIT amplifier which consists of a 2.2 m long coplanar waveguide transmission line fabricated in a double spiral format, with periodic loadings and impedance transformers at the input/output ports on a 2 by 2 cm Si chip. The design was fabricated with 20 nm NbTiN films. The device has shown over 10 dB of gain from 4 to 11 GHz. We have found the maximum gain is limited by abrupt breakdown at defects in the transmission line in the devices. By cascading two devices, more than 20 dB of gain was achieved from 4.5 to 12.5 GHz, with a peak of 27 dB.

Bockstiegel, C.; Gao, J.; Vissers, M. R.; Sandberg, M.; Chaudhuri, S.; Sanders, A.; Vale, L. R.; Irwin, K. D.; Pappas, D. P.

2014-08-01

338

[High-performance biosignal amplifier for electrophysiologic studies for special safety requirements].  

PubMed

For the recording of minute bioelectric signal voltages in the fields of medical research and diagnostic applications, a high-performance amplifier is needed to provide the signal levels necessary for a significant analysis. Irrespective of the concrete application, the major parameters required for a comparative evaluation of such systems are sensitivity, bandwidth and noise. Some applications also make special demands on electrical safety measures. With the aim of using an amplifier with a particularly powerful magnetic stimulator, and in view of the special requirements for brain voltage recording in a fully conscious patient, a universally applicable amplifier system has been developed that incorporates safety measures that ensure virtually risk-free application. The stimulation artefact can be suppressed completely by means of automatic offset regulation of the preamplifier. The circuit elements in electrical contact with the organism are separated from the rest of the measuring system by a high-voltage insulation barrier. The main innovation and central subject of this article is an active protective system with an extremely short response time, which reliably cuts off the relevant amplifier circuits as soon as the ceiling signal level is exceeded. In accordance with relevant regulations, the user is warned of any first failure by a program-controlled self-test run by the protective unit and done automatically when the amplifier is activated. Exhaustive tests with a prototype have confirmed, among other things, that the integration of the new protective device does not reduce the amplifier output to any measurable extent. PMID:7833447

Schmid, M; Weyh, T; Meyer, B U

1994-11-01

339

Improving Precision of Proximity Ligation Assay by Amplified Single Molecule Detection  

PubMed Central

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

Fredriksson, Simon; Landegren, Ulf; Nilsson, Mats

2013-01-01

340

Ku band low noise parametric amplifier  

NASA Technical Reports Server (NTRS)

A low noise, K sub u-band, parametric amplifier (paramp) was developed. The unit is a spacecraft-qualifiable, prototype, parametric amplifier for eventual application in the shuttle orbiter. The amplifier was required to have a noise temperature of less than 150 K. A noise temperature of less than 120 K at a gain level of 17 db was achieved. A 3-db bandwidth in excess of 350 MHz was attained, while deviation from phase linearity of about + or - 1 degree over 50 MHz was achieved. The paramp operates within specification over an ambient temperature range of -5 C to +50 C. The performance requirements and the operation of the K sub u-band parametric amplifier system are described. The final test results are also given.

1976-01-01

341

Hybrid waveguides for optically pumped amplifiers  

E-print Network

A hybrid waveguide based on simultaneous propagation of photonic crystal (PC) and total internal reflection confined optical modes is introduced for a scheme to uniformly pump waveguide optical amplifiers (WOAs). Planar ...

Saini, S.

342

Microwave diode amplifiers with low intermodulation distortion  

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

343

Advanced Concepts in Josephson Junction Reflection Amplifiers  

NASA Astrophysics Data System (ADS)

Low-noise amplification at microwave frequencies has become increasingly important for the research related to superconducting qubits and nanoelectromechanical systems. The fundamental limit of added noise by a phase-preserving amplifier is the standard quantum limit, often expressed as noise temperature . Towards the goal of the quantum limit, we have developed an amplifier based on intrinsic negative resistance of a selectively damped Josephson junction. Here we present measurement results on previously proposed wide-band microwave amplification and discuss the challenges for improvements on the existing designs. We have also studied flux-pumped metamaterial-based parametric amplifiers, whose operating frequency can be widely tuned by external DC-flux, and demonstrate operation at pumping, in contrast to the typical metamaterial amplifiers pumped via signal lines at.

Lähteenmäki, Pasi; Vesterinen, Visa; Hassel, Juha; Paraoanu, G. S.; Seppä, Heikki; Hakonen, Pertti

2014-06-01

344

A DC stabilized fully differential amplifier  

E-print Network

The conventional method of constructing a gain amplifier is to use resistor feedback networks. However, present CMOS technology provides capacitors that offer substantially better tracking and linearity performance over ...

Sun, Nancy Y

2005-01-01

345

Mechanical Amplifier for Translational Kinetic Energy Harvesters  

NASA Astrophysics Data System (ADS)

This paper reports the design, optimization, and test results of a mechanical amplifier coupled to an electromagnetic energy harvester to generate power from low- amplitude (±1 mm) and low-frequency (<5 Hz) vibrations in the presence of large static displacements. When coupled to a translational kinetic energy harvester, the amplifier boosts small vibration amplitudes by as much as 4x while accommodating translational displacements of more than 10x of vibration amplitudes. A complete electromagnetic energy harvester using this mechanical amplifier produces 16x improvement in output power (30 mW vs 1.9 mW without amplifier at 5 Hz), and a high power density of 170 ?W/cm3.

Shahosseini, I.; Najafi, K.

2014-11-01

346

Sensor/amplifier for weak light sources  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

347

Increasing dynamic range in microwave parametric amplifiers  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

348

A novel wideband gyrotron travelling wave amplifier  

E-print Network

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

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

2003-01-01

349

How to characterize the nonlinear amplifier?  

NASA Technical Reports Server (NTRS)

The conception of the amplification of the coherent field is formulated. The definition of the coefficient of the amplification as the relation between the mean value of the field at the output to the value at the input and the definition of the noise as the difference between the number of photons in the output mode and square of the modulus of the mean value of the output amplitude are considered. Using a simple example it is shown that by these definitions the noise of the nonlinear amplifier may be less than the noise of the ideal linear amplifier of the same amplification coefficient. Proposals to search another definition of basic parameters of the nonlinear amplifiers are discussed. This definition should enable us to formulate the universal fundamental lower limit of the noise which should be valid for linear quantum amplifiers as for nonlinear ones.

Kallistratova, Dmitri Kouznetsov; Cotera, Carlos Flores

1994-01-01

350

Two-stage hybrid microcircuit amplifier  

SciTech Connect

This report documents the design, development, and fabrication of a two-stage amplifier operating at 400 to 600 MHz. Included are characterization data, predictions generated during design, and measured performance.

Pyo, M.L.

1987-04-01

351

Fiske-amplified superfluid interferometry  

SciTech Connect

We report an experimental demonstration of signal amplification for a superfluid {sup 4}He interferometer by allowing the matter waves from two Josephson mass current sources to interact with the resonances within the experimental cell. We characterize the interferometer using an external phase shift and demonstrate a 30-fold enhancement in intrinsic phase sensitivity. We also demonstrate a truly continuous operation of this interference device.

Sato, Yuki [Rowland Institute at Harvard, Harvard University, Cambridge, Massachusetts 02142 (United States)

2010-05-01

352

Real Time Calibration Method for Signal Conditioning Amplifiers  

NASA Technical Reports Server (NTRS)

A signal conditioning amplifier receives an input signal from an input such as a transducer. The signal is amplified and processed through an analog to digital converter and sent to a processor. The processor estimates the input signal provided by the transducer to the amplifier via a multiplexer. The estimated input signal is provided as a calibration voltage to the amplifier immediately following the receipt of the amplified input signal. The calibration voltage is amplified by the amplifier and provided to the processor as an amplified calibration voltage. The amplified calibration voltage is compared to the amplified input signal, and if a significant error exists, the gain and/or offset of the amplifier may be adjusted as necessary.

Medelius, Pedro J. (Inventor); Mata, Carlos T. (Inventor); Eckhoff, Anthony (Inventor); Perotti, Jose (Inventor); Lucena, Angel (Inventor)

2004-01-01

353

MMIC Amplifiers for 90 to 130 GHz  

NASA Technical Reports Server (NTRS)

This brief describes two monolithic microwave integrated-circuit (MMIC) amplifier chips optimized to function in the frequency range of 90 to 130 GHz, covering nearly all of F-band (90 - 140 GHz). These amplifiers were designed specifically for local-oscillator units in astronomical radio telescopes such as the Atacama Large Millimeter Array (ALMA). They could also be readily adapted for use in electronic test equipment, automotive radar systems, and communications systems that operate between 90 and 130 GHz.

Samoska, Lorene; Pukala, David; Peralta, Alejandro; Bryerton, Eric; Morgan, Matt; Boyd, T.; Hu, Ming; Schmitz, Adele

2007-01-01

354

Solid State Student Guide: Power Amplifier Lab  

NSDL National Science Digital Library

In this lab, the students will analyze four different classes of amplifiers and compare their efficiencies. Students will gain a better understanding of the functions of a transistor and how MOSFETs are implemented in power amplifiers. It should take about three hours to work through the entire lab exercise. The module may be downloaded in a Zipped file which contains a Microsoft Word Doc file. A quick, free login is required to access the materials.

355

Distributed fiber Raman amplifiers with localized loss  

Microsoft Academic Search

Backward pumped C- and L-band distributed fiber Raman amplifiers are described, where discrete losses from 0-8 dB were added at various positions to examine the effect of localized loss. Below 3-dB additional loss, the overall optical performance degraded similarly, regardless of loss position in a hybrid Raman and erbium-doped fiber amplifier. Above 3 dB, the performance degradation worsened as the

Seung Kwan Kim; Sun Hyok Chang; Jin Soo Han; Moo-Jung Chu; Jong Hyun Lee

2003-01-01

356

Characteristics of low noise hybrid fiber amplifier  

Microsoft Academic Search

The characteristics of hybrid fiber amplifier (HFA) are investigated. HFA is composed of three stages: short-length EDFA pre-stage, DCF Raman amplifier, and power boosting EDFA. HFA has low noise figure, high output power, and also wide input power dynamic range. Gain control method of HFA is presented experimentally, and the transient gain excursion is suppressed to less than 0.5dB at

Sun Hyok Chang; Jin Soo Han; Hee Sang Chung; Kwangjoon Kim; Je Soo Ko

2006-01-01

357

Characteristics of low noise hybrid fiber amplifier  

Microsoft Academic Search

The characteristics of hybrid fiber amplifier (HFA) are investigated. HFA is composed of three stages: short-length EDFA pre-stage, DCF Raman amplifier, and power boosting EDFA. HFA has low noise figure, high output power, and also wide input power dynamic range. Gain control method of HFA is presented experimentally, and the transient gain excursion is suppressed to less than 0.5 dB

Sun Hyok Chang; Jin Soo Han; Hee Sang Chung; Kwangjoon Kim; Je Soo Ko

2006-01-01

358

Thulium-doped tellurite fiber amplifier  

Microsoft Academic Search

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

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

2004-01-01

359

Direct solar-pumped iodine laser amplifier  

NASA Technical Reports Server (NTRS)

This semiannual progress report covers the period from September 1, 1988 to February 28, 1989 under NASA grant NAG-1-441 entitled, Direct Solar-Pumped Iodine Laser Amplifier. During this period, the research effort was concentrated on the solar pumped master oscillator power amplifier (MOPA) system using n-C3F7I. In the experimental work, the amplification measurement was conducted to identify the optimum conditions for amplification of the center's Vortek solar simulator pumped iodine laser amplifier. A modeling effort was also pursued to explain the experimental results in the theoretical work. The amplification measurement of the solar simulator pumped iodine laser amplifier is the first amplification experiment on the continuously pumped amplifier. The small signal amplification of 5 was achieved for the triple pass geometry of the 15 cm long solar simulator pumped amplifier at the n-C3F7I pressure of 20 torr, at the flow velocity of 6 m/sec and at the pumping intensity of 1500 solar constants. The XeCl laser pumped iodine laser oscillator, which was developed in the previous research, was employed as the master oscillator for the amplification measurement. In the theoretical work, the rate equations of the amplifier was established and the small signal amplification was calculated for the solar simulator pumped iodine laser amplifier. The amplification calculated from the kinetic equations with the previously measured rate coefficients reveals very large disagreement with experimental measurement. Moreover, the optimum condition predicted by the kinetic equation is quite discrepant with that measured by experiment. This fact indicates the necessity of study in the measurement of rate coefficients of the continuously pumped iodine laser system.

Han, Kwang S.; Hwang, In Heon; Stock, Larry V.

1989-01-01

360

Capillary Array Waveguide Amplified Fluorescence Detector for mHealth  

PubMed Central

Mobile Health (mHealth) analytical technologies are potentially useful for carrying out modern medical diagnostics in resource-poor settings. Effective mHealth devices for underserved populations need to be simple, low cost, and portable. Although cell phone cameras have been used for biodetection, their sensitivity is a limiting factor because currently it is too low to be effective for many mHealth applications, which depend on detection of weak fluorescent signals. To improve the sensitivity of portable phones, a capillary tube array was developed to amplify fluorescence signals using their waveguide properties. An array configured with 36 capillary tubes was demonstrated to have a ~100X increase in sensitivity, lowering the limit of detection (LOD) of mobile phones from 1000 nM to 10 nM for fluorescein. To confirm that the amplification was due to waveguide behavior, we coated the external surfaces of the capillaries with silver. The silver coating interfered with the waveguide behavior and diminished the fluorescence signal, thereby proving that the waveguide behavior was the main mechanism for enhancing optical sensitivity. The optical configuration described here is novel in several ways. First, the use of capillaries waveguide properties to improve detection of weak florescence signal is new. Second we describe here a three dimensional illumination system, while conventional angular laser waveguide illumination is spot (or line), which is functionally one-dimensional illumination, can illuminate only a single capillary or a single column (when a line generator is used) of capillaries and thus inherently limits the multiplexing capability of detection. The planar illumination demonstrated in this work enables illumination of a two dimensional capillary array (e.g. x columns and y rows of capillaries). In addition, the waveguide light propagation via the capillary wall provides a third dimension for illumination along the axis of the capillaries. Such an array can potentially be used for sensitive analysis of multiple fluorescent detection assays simultaneously. The simple phone based capillary array approach presented in this paper is capable of amplifying weak fluorescent signals thereby improving the sensitivity of optical detectors based on mobile phones. This may allow sensitive biological assays to be measured with low sensitivity detectors and may make mHealth practical for many diagnostics applications, especially in resource-poor and global health settings. PMID:24039345

Balsam, Joshua; Bruck, Hugh Alan; Rasooly, Avraham

2013-01-01

361

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. 11 figs.

George, V.E.; Haas, R.A.; Krupke, W.F.; Schlitt, L.G.

1980-05-27

362

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

1980-05-27

363

V-band IMPATT power amplifier  

NASA Technical Reports Server (NTRS)

This program is the result of the continuing demand and future requirement for a high data rate 60-GHz communications link. A reliable solid-state transmitter which delivers the necessary power over a wide bandwidth using the present IMPATT diode technology required the development of combining techniques. The development of a 60-GHz IMPATT power combiner amplifier is detailed. The results form a basis from which future wideband, high-power IMPATT amplifiers may be developed. As a result, several state-of-the-art advancements in millimeter-wave components technology were achieved. Specific achievements for the amplifier integration were: development of a nonresonant divider/combiner circuit; reproducible multiple junction circulator assemblies; and reliable high power 60-GHz IMPATT diodes. The various design approaches and tradeoffs which lead to the final amplifier configuration are discussed. A detailed circuit design is presented for the various amplifier components, and the conical line combiner, radial line combiner, and circulator development are discussed. The performance of the amplifier, the overall achievement of the program, the implications of the results, and an assessment of future development needs and recommendations are examined.

Schell, S. W.

1985-01-01

364

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

365

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

SciTech Connect

Small-angle p-p, p-d, d-{alpha}, and {alpha}-{alpha} correlation functions were measured following the reaction {sup 16}O+{sup 27}Al at 40 MeV/nucleon {sup 16}O. These light charged particles (LCP`s) were measured with a closely packed hexagonal array of CsI detectors, located at 35{degree}, with a center to center opening angle of 2.35{degree} for adjacent detectors. Coincident particles were simultaneously detected in the NSCL 4{pi} detector. This measurement was intended to be a complement to earlier results from the same system. Based on studies of this system at lower energies and other published correlation measurements, it was expected that at 40 MeV/nucleon there would be significant positive correlations from the nuclear force and deep anticorrelations from Coulomb repulsion. However, correlation functions from this higher energy are remarkably similar to those previously measured at {approx}15 MeV/nucleon. Correlation functions formed from events with a high multiplicity or high total detected energy (central collisions) are not significantly different from the inclusive measurements. As a possible explanation we suggest that significant correlations are most readily seen in experiments sensitive to LCP`s from fast preequilibrium processes and that measurements at more backward angles are primarily sensitive to LCP`s from a longer-lived source formed after preequilibrium processes are done. This idea is supported by trends of p-p correlation functions from a wide range of systems. A schematic calculation based on a Boltzmann-Ueling-Uhlenbeck (BUU) model and statistical emission qualitatively reproduces the results from this work. {copyright} {ital 1997} {ital The American Physical Society}

DeYoung, P.A.; Dykstra, C.; Gonthier, P.; Mader, C.; Peaslee, G.F.; Peterson, D.; Sedlar, R.; Sundbeck, S.; Shaw, N. [Department of Physics, Hope College, Holland, Michigan 49422-9000 (United States)] [Department of Physics, Hope College, Holland, Michigan 49422-9000 (United States); Westfall, G.; Craig, D.; Lacey, R.; Li, T.; Reposeur, T.; VanderMolen, A.; Winfield, J.S.; Yennello, S. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States)] [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Nadasen, A. [Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, Michigan 48128 (United States)] [Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, Michigan 48128 (United States)

1997-07-01

366

Erbium\\/ytterbium co-doped double clad fiber amplifier, its applications and effects in fiber optic communication systems  

Microsoft Academic Search

Increased demand for larger bandwidth and longer inter-amplifiers distances translates to higher power budgets for fiber optic communication systems in order to overcome large splitting losses and achieve acceptable signal-to-noise ratios. Due to their unique design ytterbium sensitized erbium doped, double clad fiber amplifiers; offer significant increase in the output powers that can be obtained. In this thesis we investigate,

Puneit Dua

2005-01-01

367

Multi-pass light amplifier  

NASA Technical Reports Server (NTRS)

A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A resonator or a White Cell cavity is provided, including two or more mirrors (planar or curvilinearly shaped) facing each other along a resonator axis and an optical gain medium positioned on a resonator axis between the mirrors or adjacent to one of the mirrors. In a first embodiment, two curvilinear mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator. A second embodiment uses two curvilinear mirrors and one planar mirror, with a gain medium positioned in the optical path between each curvilinear mirror and the planar mirror. A third embodiment uses two curvilinear mirrors and two planar mirrors, with a gain medium positioned adjacent to a planar mirror. A fourth embodiment uses a curvilinear mirror and three planar mirrors, with a gain medium positioned adjacent to a planar mirror. A fourth embodiment uses four planar mirrors and a focusing lens system, with a gain medium positioned between the four mirrors. A fifth embodiment uses first and second planar mirrors, a focusing lens system and a third mirror that may be planar or curvilinear, with a gain medium positioned adjacent to the third mirror. A sixth embodiment uses two planar mirrors and a curvilinear mirror and a fourth mirror that may be planar or curvilinear, with a gain medium positioned adjacent to the fourth mirror. In a seventh embodiment, first and second mirrors face a third mirror, all curvilinear, in a White Cell configuration, and a gain medium is positioned adjacent to one of the mirrors.

Plaessmann, Henry (Inventor); Grossman, William M. (Inventor); Olson, Todd E. (Inventor)

1996-01-01

368

Automatic alignment of double optical paths in excimer laser amplifier  

NASA Astrophysics Data System (ADS)

A kind of beam automatic alignment method used for double paths amplification in the electron pumped excimer laser system is demonstrated. In this way, the beams from the amplifiers can be transferred along the designated direction and accordingly irradiate on the target with high stabilization and accuracy. However, owing to nonexistence of natural alignment references in excimer laser amplifiers, two cross-hairs structure is used to align the beams. Here, one crosshair put into the input beam is regarded as the near-field reference while the other put into output beam is regarded as the far-field reference. The two cross-hairs are transmitted onto Charge Coupled Devices (CCD) by image-relaying structures separately. The errors between intersection points of two cross-talk images and centroid coordinates of actual beam are recorded automatically and sent to closed loop feedback control mechanism. Negative feedback keeps running until preset accuracy is reached. On the basis of above-mentioned design, the alignment optical path is built and the software is compiled, whereafter the experiment of double paths automatic alignment in electron pumped excimer laser amplifier is carried through. Meanwhile, the related influencing factors and the alignment precision are analyzed. Experimental results indicate that the alignment system can achieve the aiming direction of automatic aligning beams in short time. The analysis shows that the accuracy of alignment system is 0.63?rad and the beam maximum restoration error is 13.75?m. Furthermore, the bigger distance between the two cross-hairs, the higher precision of the system is. Therefore, the automatic alignment system has been used in angular multiplexing excimer Main Oscillation Power Amplification (MOPA) system and can satisfy the requirement of beam alignment precision on the whole.

Wang, Dahui; Zhao, Xueqing; Hua, Hengqi; Zhang, Yongsheng; Hu, Yun; Yi, Aiping; Zhao, Jun

2013-05-01

369

CHARGE IMBALANCE  

SciTech Connect

The purpose of this article is to review the theory of charge imbalance, and to discuss its relevance to a number of experimental situations. We introduce the concepts of quasiparticle charge and charge imbalance, and discuss the generation and detection of charge imbalance by tunneling. We describe the relaxation of the injected charge imbalance by inelastic scattering processes, and show how the Boltzmann equation can be solved to obtain the steady state quasiparticle distribution and the charge relaxation rate. Details are given of experiments to measure charge imbalance and the charge relaxation rate when inelastic scattering is the predominant relaxation mechanism. Experiments on and theories of other charge relaxation mechanisms are discussed, namely relaxation via elastic scattering in the presence of energy gap anisotropy, or in the presence of a pair breaking mechanism such as magnetic impurities or an applied supercurrent or magnetic field. We describe three other situations in which charge imbalance occurs, namely the resistance of the NS interface, phase slip centers, and the flow of a supercurrent in the presence of a temperature gradient.

Clarke, John

1980-09-01

370

Method to amplify variable sequences without imposing primer sequences  

DOEpatents

The present invention provides methods of amplifying target sequences without including regions flanking the target sequence in the amplified product or imposing amplification primer sequences on the amplified product. Also provided are methods of preparing a library from such amplified target sequences.

Bradbury, Andrew M.; Zeytun, Ahmet

2006-11-14

371

Efficiency of low power audio amplifiers and loudspeakers  

Microsoft Academic Search

We look at the load presented to audio amplifiers by real transducers. We consider the power losses in class-AB and class-D amplifier topologies, and determine that in order to predict efficiency it is necessary to consider the amplifier\\/transducer combination. The ability of the class-D amplifier to recycle quadrature load current offers new ways to improve efficiency

S. Burrow; D. Grant

2001-01-01

372

NEW CONCEPT OF A HYBRID AMPLIFIER FOR DRIVING PIEZOELECTRIC ACTUATORS  

Microsoft Academic Search

This paper describes a new concept of an amplifier for piezoelectric actuators, which combines the high efficiency of a switching amplifier with the output signal accuracy of an analogue amplifier. This so-called hybrid amplifier includes a bidirectional switching voltage source and an analogue final stage. The description of the control unit for the switching power supply with its unconventional structure

Christoph Stiebel; Hartmut Janocha

373

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

374

Improved Grid-Array Millimeter-Wave Amplifier  

NASA Technical Reports Server (NTRS)

Improved grid-array amplifiers operating at millimeter and submillimeter wavelengths developed for use in communications and radar. Feedback suppressed by making input polarizations orthogonal to output polarizations. Amplifier made to oscillate by introducing some feedback. Several grid-array amplifiers concatenated to form high-gain beam-amplifying unit.

Rosenberg, James J.; Rutledge, David B.; Smith, R. Peter; Weikle, Robert

1993-01-01

375

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

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

376

Design of an Auto-zeroed, Differential, Organic Thin-film Field-effect Transistor Amplifier for Sensor Applications  

NASA Technical Reports Server (NTRS)

Organic strain gauge and other sensors require high-gain, precision dc amplification to process their low-level output signals. Ideally, amplifiers would be fabricated using organic thin-film field-effect transistors (OTFT's) adjacent to the sensors. However, OTFT amplifiers exhibit low gain and high input-referred dc offsets that must be effectively managed. This paper presents a four-stage, cascaded differential OTFT amplifier utilizing switched capacitor auto-zeroing. Each stage provides a nominal voltage gain of four through a differential pair driving low-impedance active loads, which provide common-mode output voltage control. p-type pentacence OTFT's are used for the amplifier devices and auto-zero switches. Simulations indicate the amplifier provides a nominal voltage gain of 280 V/V and effectively amplifies a 1-mV dc signal in the presence of 500-mV amplifier input-referred dc offset voltages. Future work could include the addition of digital gain calibration and offset correction of residual offsets associated with charge injection imbalance in the differential circuits.

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

2004-01-01

377

AIDA: A 16-channel amplifier ASIC to read out the advanced implantation detector array for experiments in nuclear decay spectroscopy  

SciTech Connect

We have designed a read-out ASIC for nuclear decay spectroscopy as part of the AIDA project - the Advanced Implantation Detector Array. AIDA will be installed in experiments at the Facility for Antiproton and Ion Research in GSI, Darmstadt. The AIDA ASIC will measure the signals when unstable nuclei are implanted into the detector, followed by the much smaller signals when the nuclei subsequently decay. Implant energies can be as high as 20 GeV; decay products need to be measured down to 25 keV within just a few microseconds of the initial implants. The ASIC uses two amplifiers per detector channel, one covering the 20 GeV dynamic range, the other selectable over a 20 MeV or 1 GeV range. The amplifiers are linked together by bypass transistors which are normally switched off. The arrival of a large signal causes saturation of the low-energy amplifier and a fluctuation of the input voltage, which activates the link to the high-energy amplifier. The bypass transistors switch on and the input charge is integrated by the high-energy amplifier. The signal is shaped and stored by a peak-hold, then read out on a multiplexed output. Control logic resets the amplifiers and bypass circuit, allowing the low-energy amplifier to measure the subsequent decay signal. We present simulations and test results, demonstrating the AIDA ASIC operation over a wide range of input signals. (authors)

Braga, D. [STFC Rutherford Appleton Laboratory, Didcot, OX11 0QX (United Kingdom); Coleman-Smith, P. J. [STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Davinson, T. [Dept. of Physics and Astronomy, Univ. of Edinburgh, Edinburgh EH9 3JZ (United Kingdom); Lazarus, I. H. [STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Page, R. D. [Dept. of Physics, Univ. of Liverpool, Oliver Lodge Laboratory, Liverpool L69 7ZE (United Kingdom); Thomas, S. [STFC Rutherford Appleton Laboratory, Didcot, OX11 0QX (United Kingdom)

2011-07-01

378

Tunable dye laser amplifier chain for laser isotope separation  

SciTech Connect

A tunable dye laser amplifier chain developed for experiments on atomic vapour laser isotope separation (AVLIS) is described. The system, pumped by copper vapour lasers, consists of a master oscillator and an amplifier stage including a preamplifier and three main amplifiers working in the saturation mode. The master oscillator of the stage is a dye laser with a grazing incidence diffraction grating. Longitudinal pumping of the amplifiers is used. The efficiency of the main amplifiers is 50 % - 55 %. The average power of laser radiation at the output of the last amplifier is 100 W. (lasers. amplifiers)

Grigoriev, Igor' S; D'yachkov, Aleksei B; Labozin, Valerii P; Mironov, Sergei M; Nikulin, Sergei A; Firsov, Valerii A [Russian Research Centre 'Kurchatov Institute', Moscow (Russian Federation)

2004-05-31

379

Can Like Charges Attract Each Other?  

ERIC Educational Resources Information Center

Electroscopes are sensitive instruments useful for investigations of static electricity. They are devices that are used for detecting whether an object is charged or uncharged. They also determine the type of charge. Their operation is based on the principle of like sign charge repulsion.

Balta, Nuri

2012-01-01

380

Internal Charging  

NASA Technical Reports Server (NTRS)

(1) High energy (>100keV) electrons penetrate spacecraft walls and accumulate in dielectrics or isolated conductors; (2) Threat environment is energetic electrons with sufficient flux to charge circuit boards, cable insulation, and ungrounded metal faster than charge can dissipate; (3) Accumulating charge density generates electric fields in excess of material breakdown strenght resulting in electrostatic discharge; and (4) System impact is material damage, discharge currents inside of spacecraft Faraday cage on or near critical circuitry, and RF noise.

Minow, Joseph I.

2014-01-01

381

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

Microsoft Academic Search

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

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

2009-01-01

382

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

Microsoft Academic Search

Self-amplified spontaneous emission in a free-electron laser has been proposed for the generation of very high brightness coherent x-rays. This process involves passing a high-energy, high-charge, short-pulse, low-energy-spread, and low-emittance electron beam through the periodic magnetic field of a long series of high-quality undulator magnets. The radiation produced grows exponentially in intensity until it reaches a saturation point. We report

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

2001-01-01

383

High power, high beam quality regenerative amplifier  

DOEpatents

A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

Hackel, L.A.; Dane, C.B.

1993-08-24

384

High power, high beam quality regenerative amplifier  

DOEpatents

A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

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

1993-01-01

385

Pulsed ti: sapphire laser power amplifier  

SciTech Connect

We have demonstrated an all solid state Ti:Sapphire laser system consisting of a power oscillator and single pass amplifier. The electrical-to-optical efficiency far exceeds that of the current CW systems. The pump lasers have lower capital and operating costs than the Argon-ion laser. In the future, we plan to scale the output power to higher levels by adding a fourth pump laser and improving the output power of the current pump lasers. Modeling results suggest that a large increase in efficiency can be realized by improving the beam quality of the pump lasers, even at the cost of reduced output power. We will explore this option by adding apertures to the cavity and/or reducing the rod diameter along with optimizing the resonator design. Other improvements in efficiency which will be investigated include double passing the amplifier for better extraction. To complete this work, the laser system will be converted into a two-stage amplifier. A narrow band, lower power oscillator currently under development will be injected in to the amplifier to study the extraction and efficiency characteristics of the amplifier throughout the tuning range of Ti:Sapphire. Detailed beam quality measurements will also be made. Other work will include doubling the narrow band output for materials processing applications.

Crozier, D W; Ault, Ault, E R; Erbert, G; Pierce, E L; Sleaford, B W

1999-02-23

386

Independent evolution of macrophage-tropism and increased charge between HIV-1 R5 envelopes present in brain and immune tissue  

PubMed Central

Background Transmitted HIV-1 clade B or C R5 viruses have been reported to infect macrophages inefficiently, while other studies have described R5 viruses in late disease with either an enhanced macrophage-tropism or carrying envelopes with an increased positive charge and fitness. In contrast, our previous data suggested that viruses carrying non-macrophage-tropic R5 envelopes were still predominant in immune tissue of AIDS patients. To further investigate the tropism and charge of HIV-1 viruses in late disease, we evaluated the properties of HIV-1 envelopes amplified from immune and brain tissues of AIDS patients with neurological complications. Results Almost all envelopes amplified were R5. There was clear compartmentalization of envelope sequences for four of the five subjects. However, strong compartmentalization of macrophage-tropism in brain was observed even when brain and immune tissue envelope sequences were not segregated. R5 envelopes from immune tissue of four subjects carried a higher positive charge compared to brain envelopes. We also confirm a significant correlation between macrophage tropism and sensitivity to soluble CD4, a weak association with sensitivity to the CD4 binding site antibody, b12, but no clear relationship with maraviroc sensitivity. Conclusions Our study shows that non-macrophage-tropic R5 envelopes carrying gp120s with an increased positive charge were predominant in immune tissue in late disease. However, highly macrophage-tropic variants with lower charged gp120s were nearly universal in the brain. These results are consistent with HIV-1 R5 envelopes evolving gp120s with an increased positive charge in immune tissue or sites outside the brain that likely reflect an adaptation for increased replication or fitness for CD4+ T-cells. Our data are consistent with the presence of powerful pressures in brain and in immune tissues selecting for R5 envelopes with very different properties; high macrophage-tropism, sCD4 sensitivity and low positive charge in brain and non-macrophage-tropism, sCD4 resistance and high positive charge in immune tissue. PMID:22420378

2012-01-01

387

Polymerization amplified detection for nanoparticle-based biosensing.  

PubMed

Efficient signal amplification processes are key to the design of sensitive assays for biomolecule detection. Here, we describe a new assay platform that takes advantage of both polymerization reactions and the aggregation of nanoparticles to amplify signal. In our design, a cascade is set up in which radicals generated by either enzymes or metal ions are polymerized to form polymers that can entangle multiple gold nanoparticles (AuNPs) into aggregates, resulting in a visible color change. Less than 0.05% monomer-to-polymer conversion is required to initiate aggregation, providing high sensitivity toward the radical generating species. Good sensitivity of this assay toward horseradish peroxidase, catalase, and parts per billion concentrations of iron and copper is shown. Incorporation of the oxygen-consuming enzyme glucose oxidase (GOx), enables this assay to be performed in open air conditions at ambient temperature. We anticipate that such a design will provide a useful platform for sensitive detection of a broad range of biomolecules through polymerization-based amplification. PMID:25315059

Gormley, Adam J; Chapman, Robert; Stevens, Molly M

2014-11-12

388

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

PubMed

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

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

2015-02-15

389

Short pulse free electron laser amplifier  

DOEpatents

Method and apparatus for amplification of a laser pulse in a free electron laser amplifier where the laser pulse duration may be a small fraction of the electron beam pulse duration used for amplification. An electron beam pulse is passed through a first wiggler magnet and a short laser pulse to be amplified is passed through the same wiggler so that only the energy of the last fraction, f, (f<1) of the electron beam pulse is consumed in amplifying the laser pulse. After suitable delay of the electron beam, the process is repeated in a second wiggler magnet, a third, . . . , where substantially the same fraction f of the remainder of the electron beam pulse is consumed in amplification of the given short laser pulse in each wiggler magnet region until the useful electron beam energy is substantially completely consumed by amplification of the laser pulse.

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

1985-01-01

390

Phase noise of oscillators with unsaturated amplifiers  

NASA Astrophysics Data System (ADS)

We study the role of amplifier saturation in eliminating feedback noise in self-sustained oscillators. We extend previous works that use a saturated amplifier to quench fluctuations in the feedback magnitude, while simultaneously tuning the oscillator to an operating point at which the resonator nonlinearity cancels fluctuations in the feedback phase. We consider a generalized model which features an amplitude-dependent amplifier gain function. This allows us to determine the total oscillator phase noise in realistic configurations due to noise in both quadratures of the feedback, and to show that it is not necessary to drive the resonator to large oscillation amplitudes in order to eliminate noise in the phase of the feedback.

Kenig, Eyal; Cross, M. C.; Moehlis, Jeff; Wiesenfeld, Kurt

2013-12-01

391

Ultrashort pulse amplification in cryogenically cooled amplifiers  

DOEpatents

A laser amplifier system amplifies pulses in a single "stage" from .about.10.sup.-9 joules to more than 10.sup.-3 joules, with average power of 1-10 watts, and beam quality M.sup.2 <2. The laser medium is cooled substantially below room temperature, as a means to improve the optical and thermal characteristics of the medium. This is done with the medium inside a sealed, evacuated or purged cell to avoid moisture or other materials condensing on the surface. A "seed" pulse from a separate laser is passed through the laser medium, one or more times, in any of a variety of configurations including single-pass, multiple-pass, and regenerative amplifier configurations.

Backus, Sterling J.; Kapteyn, Henry C.; Murnane, Margaret Mary

2004-10-12

392

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

393

A variable-gain optical amplifier for metro WDM networks with mixed span losses: a gain-clamped semiconductor optical amplifier combined with a Raman fiber amplifier  

Microsoft Academic Search

We propose a variable-gain optical amplifier that exhibits excellent performance in metro wavelength-division-multiplexing networks containing mixed span losses. The amplifier consists of a variable-gain Raman fiber amplifier and a gain-clamped semiconductor optical amplifier. Each span of different loss is exactly compensated by adjusting the pump power of a Raman laser diode to have the maximum optical signal-to-noise ratio. Sixteen channels

H. H. Lee; J. M. Oh; D. Lee; J. Han; H. S. Chung; K. Kim

2005-01-01

394

A gain-clamped-semiconductor-optical-amplifier combined with a distributed Raman-fiber-amplifier: a good candidate as an inline amplifier for WDM networks  

Microsoft Academic Search

A gain-clamped semiconductor optical amplifier (SOA) is used as an inline amplifier in combination with a distributed Raman fiber amplifier. The combined amplifier has 20 dB gain and a noise figure below 2.7 dB. The optical signal to noise ratios after five spans of 20 dB loss, equivalent to 5×80 km, are over 25.2 dB for eight-channel transmissions. In addition,

H. H. Lee; D. Lee; H. S. Chung

2004-01-01

395

Sensitivity of crystal video receivers  

NASA Astrophysics Data System (ADS)

Tangential sensitivity is shown to be an inadequate criterion for comparing the operational performance of wideband crystal video ESM receivers. By contrast, it is shown that receiver sensitivity is completely described by a criterion that specifies a required signal detection probability for a given false-alarm rate. In particular, this alternative criterion is necessary for the correct design of modern ESM receivers that incorporate automatic processors. Formulas are presented relating explicitly three system descriptors: (1) detection probability, (2) false-alarm rate, and (3) tangential sensitivity, and it is shown that a general system description is provided by any two of these three. It is also shown that a sensitivity figure can be defined including these terms in an effective receiver bandwidth. The sensitivity equations are also derived for receivers in which noise from both the detectors and the video amplifier becomes significant.

Edwards, J.

1985-07-01

396

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

SciTech Connect

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

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

2011-09-30

397

Resonance shift in relativistic traveling wave amplifiers  

SciTech Connect

We examine analytically the linear operation of relativistic traveling wave tube amplifiers. In this regime it is found that the maximum growth rate occurs at a beam velocity below that expected on the basis of resonance with the cold dispersion relation of the slow wave structure. The maximum growth rate can be much larger than that at the resonance condition. These results have significance when extending Pierce{close_quote}s theory to traveling wave amplifiers driven by relativistic electron beams. {copyright} {ital 1996 The American Physical Society.}

Naqvi, S.A.; Kerslick, G.S.; Nation, J.A. [School of Electrical Engineering & Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States)] [School of Electrical Engineering & Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States); Schaechter, L. [Department of Electrical Engineering, Technion--Israel Institute of Technology, Haifa 32000 (Israel)] [Department of Electrical Engineering, Technion--Israel Institute of Technology, Haifa 32000 (Israel)

1996-04-01

398

Master-Oscillator/Power-Amplifier Laser System  

NASA Technical Reports Server (NTRS)

Master-oscillator/power-amplifier (MOPA) laser system operates in continuous-wave mode or in amplitude-modulation (e.g., pulse) mode by modulation of oscillator current. Power amplifier is laser-diode-pumped neodymium:yttrium lithium fluoride (Nd:YLF) laser; oscillator is laser diode. Offers relatively high efficiency and power. Because drive current to oscillator modulated, external electro-optical modulator not needed. Potential uses include free-space optical communications, coded laser ranging, and generation of high-power, mode-locked pulses.

Yu, Anthony W.; Krainak, Michael A.; Unger, Glenn L.

1994-01-01

399

Coaxial extraction of RF power from a traveling wave amplifier  

SciTech Connect

The authors present new results from a high-power relativistic traveling wave tube amplifier experiment in which the RF power is extracted in a coaxial output section. The amplifier consists of two slow-wave structures separated by a resistive sever. The first stage imparts a small modulation to the beam. The second stage consists of an iris-loaded circular waveguide which is tapered from both ends by an adiabatic increase in the iris aperture with each successive period. The periodic length and the external cavity radius are kept constant. This provides a low-reflection transition from the slow-wave structure to the empty circular waveguide. A coaxial inner conductor is inserted into the output tapered section of the slow-wave structure and its` position and radius chosen to minimize reflections and maximize extracted RF power. It is shown both experimentally and through MAGIC simulations that a fairly low reflection circular TM{sub 01} to coaxial TEM mode transition can be made this way. Any small reflections form the output end travel backwards and are absorbed in the sever. In contrast to the traditional transverse extraction of power into a rectangular waveguide, the coaxial extraction is fairly broadband and exhibits much lower sensitivity to dimensions. The beam is dumped through an aperture in the inner conductor. Presently, the power is extracted into the coaxial waveguide and absorbed into a tapered resistive load. This will be later converted to the TE{sub 10} mode of a rectangular waveguide.

Naqvi, S.; Kerslick, G.S.; Nation, J.A.; Schaecter, L. [Cornell Univ., Ithaca, NY (United States)

1996-12-31

400

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

PubMed

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

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

2014-05-28

401

Multi-pass amplifier architecture for high power laser systems  

SciTech Connect

A main amplifier system includes a first reflector operable to receive input light through a first aperture and direct the input light along an optical path. The input light is characterized by a first polarization. The main amplifier system also includes a first polarizer operable to reflect light characterized by the first polarization state. The main amplifier system further includes a first and second set of amplifier modules. Each of the first and second set of amplifier modules includes an entrance window, a quarter wave plate, a plurality of amplifier slablets arrayed substantially parallel to each other, and an exit window. The main amplifier system additionally includes a set of mirrors operable to reflect light exiting the first set of amplifier modules to enter the second set of amplifier modules and a second polarizer operable to reflect light characterized by a second polarization state.

Manes, Kenneth R; Spaeth, Mary L; Erlandson, Alvin C

2014-04-01

402

Design of a Programmable Gain, Temperature Compensated Current-Input Current-Output CMOS Logarithmic Amplifier.  

PubMed

This paper presents the design of a programmable gain, temperature compensated, current-mode CMOS logarithmic amplifier that can be used for biomedical signal processing. Unlike conventional logarithmic amplifiers that use a transimpedance technique to generate a voltage signal as a logarithmic function of the input current, the proposed approach directly produces a current output as a logarithmic function of the input current. Also, unlike a conventional transimpedance amplifier the gain of the proposed logarithmic amplifier can be programmed using floating-gate trimming circuits. The synthesis of the proposed circuit is based on the Hart's extended translinear principle which involves embedding a floating-voltage source and a linear resistive element within a translinear loop. Temperature compensation is then achieved using a translinear-based resistive cancelation technique. Measured results from prototypes fabricated in a 0.5 ? m CMOS process show that the amplifier has an input dynamic range of 120 dB and a temperature sensitivity of 230 ppm/ (°)C (27 (°)C- 57(°)C), while consuming less than 100 nW of power. PMID:23955789

Gu, Ming; Chakrabartty, Shantanu

2013-08-15

403

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

404

CHARGE syndrome  

PubMed Central

CHARGE syndrome was initially defined as a non-random association of anomalies (Coloboma, Heart defect, Atresia choanae, Retarded growth and development, Genital hypoplasia, Ear anomalies/deafness). In 1998, an expert group defined the major (the classical 4C's: Choanal atresia, Coloboma, Characteristic ears and Cranial nerve anomalies) and minor criteria of CHARGE syndrome. Individuals with all four major characteristics or three major and three minor characteristics are highly likely to have CHARGE syndrome. However, there have been individuals genetically identified with CHARGE syndrome without the classical choanal atresia and coloboma. The reported incidence of CHARGE syndrome ranges from 0.1–1.2/10,000 and depends on professional recognition. Coloboma mainly affects the retina. Major and minor congenital heart defects (the commonest cyanotic heart defect is tetralogy of Fallot) occur in 75–80% of patients. Choanal atresia may be membranous or bony; bilateral or unilateral. Mental retardation is variable with intelligence quotients (IQ) ranging from normal to profound retardation. Under-development of the external genitalia is a common finding in males but it is less apparent in females. Ear abnormalities include a classical finding of unusually shaped ears and hearing loss (conductive and/or nerve deafness that ranges from mild to severe deafness). Multiple cranial nerve dysfunctions are common. A behavioral phenotype for CHARGE syndrome is emerging. Mutations in the CHD7 gene (member of the chromodomain helicase DNA protein family) are detected in over 75% of patients with CHARGE syndrome. Children with CHARGE syndrome require intensive medical management as well as numerous surgical interventions. They also need multidisciplinary follow up. Some of the hidden issues of CHARGE syndrome are often forgotten, one being the feeding adaptation of these children, which needs an early aggressive approach from a feeding team. As the child develops, challenging behaviors become more common and require adaptation of educational and therapeutic services, including behavioral and pharmacological interventions. PMID:16959034

Blake, Kim D; Prasad, Chitra

2006-01-01

405

Processing of optical combs with fiber optic parametric amplifiers.  

PubMed

Low noise optical frequency combs consist of equally spaced narrow-linewidth optical tones. They are useful in many applications including, for example, line-by-line pulse shaping, THz generation, and coherent communications. In such applications the comb spacing, extent of spectral coverage, degree of spectral flatness, optical tone power and tone-to-noise ratio represent key considerations. Simultaneously achieving the level of performance required in each of these parameters is often challenging using existing comb generation technologies. Herein we suggest and demonstrate how fiber optic parametric amplifiers can be used to enhance all of these key comb parameters, allowing frequency span multiplication, low noise amplification with simultaneous comb spectrum flattening, and improvement in optical tone-to-noise ratio through various phase insensitive as well as phase sensitive implementations. PMID:22535096

Slavík, R; Kakande, J; Petropoulos, P; Richardson, D J

2012-04-23

406

Low phase noise oscillator using two parallel connected amplifiers  

NASA Technical Reports Server (NTRS)

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

Kleinberg, Leonard L.

1987-01-01

407

Electron Beam Emission from a Diamond-Amplifier Cathode  

SciTech Connect

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

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

2011-12-31

408

Charge transport  

NASA Astrophysics Data System (ADS)

We report results from theoretical studies of charge and energy dynamics in organic molecular and polymeric systems. The studies were performed by employing an extended three-dimensional version of the Su-Schrieffer-Heeger model. The equation of motion for the lattice as well as the time dependent Schrodinger equation were solved simultaneously. The dynamics of charge transport and charge separation in conjugated polymeric systems have been investigated as well as the time evolution following the injection of hot electrons and excitons. The results of such studies will contribute to the understanding and the development of organic electronic and photovoltaic devices as well as artificial photosynthesis.

Stafstrãm, Sven; Boman, Magnus; Hultell Andersson, Magnus

2004-03-01

409

Low-common-mode differential amplifier  

NASA Technical Reports Server (NTRS)

Outputs of differential amplifier are excellently matched in phase and amplitude over wide range of frequencies. Common mode feedback loop offsets differences between two signal paths. Possible applications of circuit are in oscilloscopes, integrated circuit logic tester, and other self contained instruments.

Morrison, S.

1980-01-01

410

Quantum noise minimization in transistor amplifiers  

E-print Network

General quantum restrictions on the noise performance of linear transistor amplifiers are used to identify the region in parameter space where the quantum-limited performance is achievable and to construct a practical procedure for approaching it experimentally using only the knowledge of directly measurable quantities: the gain, (differential) conductance and the output noise. A specific example of resonant barrier transistors is discussed.

U. Gavish; B. Yurke; Y. Imry

2006-04-10

411

Erbium-doped and Raman fiber amplifiers  

Microsoft Academic Search

This paper provides keys to understand why erbium-doped fiber amplifiers (EDFA) have revolutionized signal transmission techniques and how they can complement with Raman amplification in the next generation of telecommunications systems. The basic physics of EDFAs is first reviewed, followed by a description of requirements for both terrestrial and submarine system applications. The related characteristics and second-order effects causing limitations

Dominique Bayart

2003-01-01

412

Broadband Raman amplifiers in modern telecommunication systems  

Microsoft Academic Search

phenomenas and providing better features in certain areas which is able to fulfill the requirements of the wavelength division multiplexed (WDM) systems regarding the wild amplification region and flatness. Among others, Raman amplifiers which use the Raman scattering eect merit big attention whose technological background is still given and whose applicable fields are the subject of recent papers frequently. We

Varallyay Zoltan; Varga Gabor; Jakab Laszlo; Richter Peter

413

A novel wideband 140 GHz gyrotron amplifier  

E-print Network

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

Joye, Colin D., 1980-

2008-01-01

414

Optical amplifier-powered quantum optical amplification  

E-print Network

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.

John Jeffers

2011-05-16

415

An Analysis of Magnetic Amplifiers with Feedback  

Microsoft Academic Search

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

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

1949-01-01

416

Fiber gratings in lasers and amplifiers  

Microsoft Academic Search

The emergence of UV-written fiber gratings, both short and long period, as a reliable fiber technology has revolutionized the field of active fiber devices. The advantageous properties of spectral selectivity, low insertion loss, and component ruggedness have made devices possible that would not be viable without their use. The use of fiber gratings in conjunction with erbium-doped fiber amplifiers (EDFAs),

Jean-Luc Archambault; Stephen G. Grubb

1997-01-01

417

Reflected-wave maser. [low noise amplifier  

NASA Technical Reports Server (NTRS)

A number of traveling-wave, slow-wave maser structures, containing active maser material but absent the typical ferrite isolators, are immersed in a nonuniform magnetic field. The microwave signal to be amplified is inserted at a circulator which directs the signal to a slow-wave structure. The signal travels through the slow-wave structure, being amplified according to the distance traveled. The end of the slow-wave structure farthest from the circulator is arranged to be a point of maximum reflection of the signal traveling through the slow-wave structure. As a consequence, the signal to be amplified traverses the slow-wave structure again, in the opposite direction (towards the circulator) experiencing amplification equivalent to that achieved by a conventional traveling-wave maser having twice the length. The circulator directs the amplified signal to following like stages of amplification. Isolators are used in between stages to prevent signals from traveling in the wrong direction, between the stages. Reduced signal loss is experienced at each stage. The high gain produced by each slow-wave structure is reduced to a moderate value by use of a nonuniform magnetic field which also broadens the line width of the maser material. The resulting bandwidth can be exceptionally wide. Cascaded stages provide high gain, exceptionally wide bandwith and very low noise temperature.

Clauss, R. C. (inventor)

1976-01-01

418

Fiber lasers and amplifiers by: Khanh Kieu  

E-print Network

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

Kieu, Khanh

419

Fiber lasers and amplifiers by: Khanh Kieu  

E-print Network

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

Kieu, Khanh

420

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.

2012-06-26

421

Neutrino charge radius and substructure  

Microsoft Academic Search

We use the recent data on numue --> numue and numue --> numue from the CHARM Collaboration to put bounds on possible non-gauge behavior of the charged weak boson. Indeed, present data allow for a neutrino charge radius <~10-32cm2. Since this latter quantity is sensitive to magnetic dipole and electric quadrupole moments of W+\\/- one can estimate from neutral-current data

A. Grau; J. A. Grifols

1986-01-01

422

A 250 GHz photonic band gap gyrotron amplifier  

E-print Network

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

Nanni, Emilio A. (Emilio Alessandro)

2013-01-01

423

Transistor circuit increases range of logarithmic current amplifier  

NASA Technical Reports Server (NTRS)

Circuit increases the range of a logarithmic current amplifier by combining a commercially available amplifier with a silicon epitaxial transistor. A temperature compensating network is provided for the transistor.

Gilmour, G.

1966-01-01

424

Amplified electrochemiluminescence detection of cancer cells using a new bifunctional quantum dot as signal probe.  

PubMed

In this work, we prepared a new electrochemiluminescent signal probe using a small bifunctional composite quantum dot (QD) with intense electrochemiluminescence (ECL) and excellent magnetic property, and developed a sensitive ECL biosensor for detection of cancer cells via DNA cyclic amplification technique. The graphene oxide (GO) with unique electrical properties was used as nano-amplified platform to immobilize a large number of capture DNA (c-DNA1). The endonuclease-assisted amplification technique was applied to amplify the ECL signal change induced by target cells. Specifically, the bifunctional composite QDs with excellent magnetic property can be conveniently labeled, separated, and developed the ECL signal probe, thus an ECL method for rapid and sensitive detection of cancer cells was developed. So far, it is for the first time that the small magnetic electrochemiluminescent QDs were applied to the assays of cancer cells by using amplification strategy, which is expected to have great potential for early clinical diagnosis of cancer. PMID:23891800

Jie, Guifen; Zhao, Yanbin; Niu, Shuyan

2013-12-15

425

Energy extraction from a large-volume HF laser amplifier  

Microsoft Academic Search

Energy extraction from a large-volume HF laser amplifier has been measured as a function of input intensity. Both the oscillator and amplifier were operated with similar gas mixtures of H2 and F2, which assured a good spectral match between the oscillator and amplifier. The amplifier input intensity was varied from 10,000 to 20,000,000 W\\/sq cm. An input intensity of 20,000,000

J. M. Hoffman; E. L. Patterson; R. A. Gerber

1979-01-01

426

Dynamics of high-power erbium-ytterbium fiber amplifiers  

Microsoft Academic Search

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

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

2005-01-01

427

Development of Submillimeter SIS Mixers and Broadband HEMT Amplifiers  

NASA Technical Reports Server (NTRS)

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

Zmuidzinas, J.

2004-01-01

428

Radiation effects on fiber amplifiers: design of radiation tolerant Yb\\/Er-based devices  

Microsoft Academic Search

Rare-earth doped optical fibers have been shown to be very sensitive to radiations, limiting the integration of fiber-based systems in space missions. In this paper, we present the characterization of two amplifiers based on a set of prototype active Erbium\\/Ytterbium codoped double clad fibers developed by Ixfiber SAS. One of these fibers has been codoped with cerium inside its core

Sylvain Girard; Arnaud Laurent; Marilena Vivona; Claude Marcandella; Thierry Robin; Benoît Cadier; Aziz Boukenter; Youcef Ouerdane

2011-01-01

429

LM2900, LM3900 QUADRUPLE NORTON OPERATIONAL AMPLIFIERS  

E-print Network

LM2900, LM3900 QUADRUPLE NORTON OPERATIONAL AMPLIFIERS SLOS059 ­ JULY 1979 ­ REVISED SEPTEMBER 1990 frequency-compensated Norton operational amplifiers that were designed specifically to operate from a single+ 4IN­ 4OUT 3OUT 3IN­ N PACKAGE (TOP VIEW) symbol (each amplifier) #12;LM2900, LM3900 QUADRUPLE NORTON

Lanterman, Aaron

430

Tunable dye laser amplifier chain for laser isotope separation  

Microsoft Academic Search

A tunable dye laser amplifier chain developed for experiments on atomic vapour laser isotope separation (AVLIS) is described. The system, pumped by copper vapour lasers, consists of a master oscillator and an amplifier stage including a preamplifier and three main amplifiers working in the saturation mode. The master oscillator of the stage is a dye laser with a grazing incidence

Igor S Grigoriev; Aleksei B Dyachkov; Valerii P Labozin; Sergei M Mironov; Sergei A Nikulin; Valerii A Firsov

2004-01-01

431

Extreme events in fiber based amplifiers Kamal Hammani 1  

E-print Network

amplifiers have indeed been a key ingredient of the telecommunication revolution of the last decade investigate Raman and parametric amplifiers pumped by a partially incoherent field, and we will outline will propose strategies to isolate the rarest events. 2. EXTREME EVENTS IN RAMAN AMPLIFIERS We first

Paris-Sud XI, Université de

432

High power X-band coaxial amplifier experiments  

Microsoft Academic Search

The authors consider the continuing studies on the development of X-band coaxial microwave amplifiers as a source for next generation linear colliders. Coaxial amplifiers employ an annular electron beam propagating between inner and outer drift tube conductors, a configuration which allows large increases in beam current over standard pencil beam amplifiers. Large average diameter systems may still be used without

T. J. Davis; J. A. Nation

1991-01-01

433

A New Method of Characterizing Amplifier Noise Performance  

Microsoft Academic Search

Although the use of noise figure or noise temperature to characterize amplifier performance is a well-established practice, it is also recognized that this parameter provides only a partial description of the amplifier noise properties. In general, the noise figure (or temperature) depends upon the generator impedance and is thus a function of the signal-source and amplifier combination. Typically, the noise

Glenn F. Engen

1970-01-01

434

Linearization of RF Power Amplifiers Using Adaptive Kalman Filtering Algorithm  

E-print Network

Linearization of RF Power Amplifiers Using Adaptive Kalman Filtering Algorithm Smail Bachir://laii.univ-poitiers.fr/ In this paper, a new linearization algorithm of Power Amplifier, based on Kalman filter- ing theory is proposed-frequency Power Amplifier. To reduce the complexity of computing in classical Kalman Filtering, a sliding time

Boyer, Edmond

435

Title of Thesis: ADVANCED OVERMODED CIRCUITS FOR GYRO-AMPLIFIERS  

E-print Network

ABSTRACT Title of Thesis: ADVANCED OVERMODED CIRCUITS FOR GYRO-AMPLIFIERS Degree candidate: Yingyu with cavity-related gyro- amplifiers, a new interaction circuit, containing clustered cavities is considered. In particular, the use of a cluster of cavities in frequency multiplying gyro-amplifiers is described

Anlage, Steven

436

MODEL SR830 DSP Lock-In Amplifier  

E-print Network

MODEL SR830 DSP Lock-In Amplifier 1290-D Reamwood Avenue Sunnyvale, California 94089 Phone: (408-9 Storing and Recalling Setups 2-13 Aux Outputs and Inputs 2-15 SR830 BASICS What is a Lock-in Amplifier? 3 Amplifier and Filters 3-17 Input Connections 3-19 Intrinsic (Random) Noise Sources 3-21 External Noise

Woodall, Jerry M.

437

Characterization of Flux-driven Josephson Parametric Amplifiers  

E-print Network

Characterization of Flux-driven Josephson Parametric Amplifiers Diploma Thesis Alexander Theodor in circuit QED have to be amplified before they can be detected. However, the predominantly used linear, phase- insensitive amplifiers inevitably add noise to the signal that may be much larger than the signal

Gross, Rudolf

438

Using Nondeterminism to Amplify Hardness # Alexander Healy + Salil Vadhan #  

E-print Network

Using Nondeterminism to Amplify Hardness # Alexander Healy + Salil Vadhan # Division of Engineering revisit the problem of hardness amplification in NP , as recently studied by O'Donnell (STOC `02). We amplify to hardness 1/2 - 1/n #(1) . 2. If s(n) = 2 n# , we amplify to hardness 1/2 - 1/2 n# . 3. If s

Vadhan, Salil

439

Using Nondeterminism to Amplify Hardness # Alexander Healy + Salil Vadhan #  

E-print Network

Using Nondeterminism to Amplify Hardness # Alexander Healy + Salil Vadhan # Division of Engineering revisit the problem of hardness amplification in NP , as recently studied by O'Donnell (JCSS `04). We amplify to hardness 1/2 - 1/n #(1) . 2. If s(n) = 2 n# , we amplify to hardness 1/2 - 1/2 n# . 3. If s

Vadhan, Salil

440

Using Nondeterminism to Amplify Hardness Alexander Healy # Salil Vadhan +  

E-print Network

Using Nondeterminism to Amplify Hardness Alexander Healy # Salil Vadhan + Harvard University Emanuele Viola # ABSTRACT We revisit the problem of hardness amplification in NP, as recently studied by O(n) = n #(1) , we amplify to hardness 1/2 - 1/n #(1) . 2. If s(n) = 2 n #(1) , we amplify to hardness 1

Viola, Emanuele

441

100 h SQUID AMPLIFIERS FOR THE ULTRACRYOGENIC GRAVITATIONAL WAVE DETECTORS  

E-print Network

100 �h SQUID AMPLIFIERS FOR THE ULTRACRYOGENIC GRAVITATIONAL WAVE DETECTORS PAOLO FALFERI, MICHELE of the cryogenic resonant de­ tectors is the noise temperature of the dc SQUID amplifier used to detect the signal matching between SQUID amplifier and displacement transducer, this limit can be approached also with finite

442

Characterization of an Ultrafast Optical Parametric Amplifier System  

E-print Network

pulse width of the ultrafast laser system. An optical parametric amplifier employs nonlinear wave mixing and Theory 6 A. Ultrafast Lasers 6 B. Nonlinear Optics 8 C. Optical Parametric Amplifier 14 IV. Experimental amplifier to characterize it for future spectroscopy experiments. #12;4 II. Introduction Nonlinear optics

Reilly, Anne

443

Signal Conditioning Amplifier and Recorder (SCAmpR)  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

444

High gain, multiatmosphere CO2 laser amplifier  

NASA Astrophysics Data System (ADS)

A novel TE discharge, 15-mm aperture, multiatmosphere, CO2 laser amplifier is described, with measured electrical characteristics and gain measurements on the 9.294-micron, 9R (16) line. The electrical circuit used in this amplifier is a realistic alternative to the Marx bank or conventional LC inversion circuit and, similarly, it would be useful for excitation of other gas lasers as well. This automatically preionized, double-sided, fourfold LC inversion circuit uses only one spark gap, and it is shown to provide small-signal gains of 5.7 percent/cm, at 120 J/l atm and 10 atm. The generalization to an n-stage device, which would be suitable for higher pressures, and larger apertures, is discussed.

Stuart, G. C.; Houtman, H.; Meyer, J.

1987-02-01

445

Magnetic Amplifier for Power Flow Control  

SciTech Connect

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

None

2012-02-24

446

Cryogenic cooling for high power laser amplifiers  

NASA Astrophysics Data System (ADS)

Using DPSSL (Diode Pumped Solid State Lasers) as pumping technology, PW-class lasers with enhanced repetition rates are developed. Each of the Yb YAG amplifiers will be diode-pumped at a wavelength of 940 nm. This is a prerequisite for achieving high repetition rates (light amplification duration 1 millisecond and repetition rate 10 Hz). The efficiency of DPSSL is inversely proportional to the temperature, for this reason the slab amplifier have to be cooled at a temperature in the range of 100 K-170 K with a heat flux of 1 MW*m-2. This paper describes the thermo-mechanical analysis for the design of the amplification laser head, presents a preliminary proposal for the required cryogenic cooling system and finally outlines the gain of cryogenic operation for the efficiency of high pulsed laser.

Perin, J. P.; Millet, F.; Divoky, M.; Rus, B.

2013-11-01

447

Ideal photon number amplifier and duplicator  

NASA Technical Reports Server (NTRS)

The photon number-amplification and number-duplication mechanism are analyzed in the ideal case. The search for unitary evolutions leads to consider also a number-deamplification mechanism, the symmetry between amplification and deamplification being broken by the integer-value nature of the number operator. Both transformations, amplification and duplication, need an auxiliary field which, in the case of amplification, turns out to be amplified in the inverse way. Input-output energy conservation is accounted for using a classical pump or through frequency-conversion of the fields. Ignoring one of the fields is equivalent to considering the amplifier as an open system involving entropy production. The Hamiltonians of the ideal devices are given and compared with those of realistic systems.

Dariano, G. M.

1992-01-01

448

Direct solar-pumped iodine laser amplifier  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

449

Wideband DMOS amplifier competes with bipolars  

NASA Astrophysics Data System (ADS)

A wideband (40-350 MHz) hybrid DMOS or double-diffused metal oxide semiconductor amplifier is described that has been designed and built to demonstrate the feasibility of the device in cable communications systems (currently dominated by bipolar hybrid IC). The advantages of the DMOS transistor include high input impedance, high current gain and power gain, and no thermal runaway problems. Furthermore, in a DMOS, a very short channel length (a micron or less) is possible without submicrometer lithography, and a high breakdown voltage can be obtained and tailored independently of the channel length by incorporating a lightly doped drift region between the active region and the drain contact. Three circuit configurations were investigated: multiple feedback, cascode, and cascade. Thick-film technology was used to implement the circuit. Amplifier characteristics are tabulated.

Salama, C. A. T.; Sin, J. K. O.

1986-06-01

450

Simple Introduction to Transistor (BJT) Amplifier  

E-print Network

"inject" the signal we want to amplify 1 mA 3. Ohms law sets emitter current 1.0v / 1000 = 1mA VC = 10V 4. Ohms law says 10V across RC, putting the collector at VC = 10 V 1mA Ã? 10k = 10v 1.7V 1. Voltage... we can also use a water model BJT Water Model Fig. 28.5 from Electrical Engineering Uncovered Base

Fowler, Mark

451

A 100-element HBT grid amplifier  

Microsoft Academic Search

A 100-element 10-GHz grid amplifier has been developed. The active devices in the grid are chips with heterojunction-bipolar-transistor (HBT) differential pairs. The metal grid pattern was empirically designed to provide effective coupling between the HBTs and free space. Two independent measurements, one with focusing lenses and the other without, were used to characterize the grid. In each case, the peak

Moonil Kim; Emilio A. Sovero; Jonathan B. Hacker; Michael P. De Lisio; Jung-Chih Chiao; Shi-Jie Li; David R. Gagnon; James J. Rosenberg; David B. Rutledge

1993-01-01

452

Analysis of multistage amplifier-frequency compensation  

Microsoft Academic Search

Frequency-compensation techniques of single-, two- and three-stage amplifiers based on Miller pole splitting and pole-zero cancellation are re-analyzed. The assumptions made, transfer functions, stability criteria, bandwidths, and important design issues of most of the reported topologies are included. Several proposed methods to improve the published topologies are given. In addition, simulations and experimental results are provided to verify the analysis

Ka Nang Leung; Philip K. T. Mok

2001-01-01

453

An X-band gigawatt amplifier  

Microsoft Academic Search

In an X-band Cerenkov amplifier driven by a 0.8-MeV 6-kA electron beam, a gigawatt-level of power radiated in a Gaussian pattern in a 70-ns pulse duration has been demonstrated. The coherence of the output radiation is provided by dividing the oversized interaction space into separate sections with different azimuthal symmetry that couples only with the electron beam. A large gain

Edward B. Abubakirov; Andrew N. Denisenko; Mikhail I. Fuks; Nikolay G. Kolganov; Nikolay F. Kovalev; Mikhail I. Petelin; Alexander V. Savelyev; Edl Schamiloglu; Eugeny I. Soluyanov; Vladimir V. Yastrebov

2002-01-01

454

Induction filtering for proportional counter amplifiers  

SciTech Connect

The interesting range of the neutron spectrum infusion blankets includes all energies up to 14 MeV. A limited region of this spectrum (from 1 keV to 1 MeV) is amenable to recoil-proton proportional counting and these measurements are now made routinely at the FNS facility at JAERI. One aspect of proportional counter measurements is a consequence of the necessity to acquire data at the lower energies in the presence of much more numerous events of higher energy which overload and saturate pulse amplifiers. Saturation, together with high count rates required for good statistical measurement precision, can introduce systematic errors into the determination of proton recoil distributions. Here we treat this overload distortion problem by a filtering technique designed specifically for the unique ionization response of the proportional counter. Amplifiers having optimal filtering will provide measured proton recoil spectra with substantially less distortion than amplifiers optimized for other types of detectors. 7 refs., 12 figs., 2 tabs.

Bennett, E.F.

1989-03-01

455

LLNL/Lion Precision LVDT amplifier  

NASA Astrophysics Data System (ADS)

A high-precision, low-noise, LVDT amplifier has been developed which is a significant advancement on the current state of the art in contact displacement measurement. This amplifier offers the dynamic range of a typical LVDT probe but with a resolution that rivals that of non contact displacement measuring systems such as capacitance gauges and laser interferometers. Resolution of 0.1 (mu) in with 100 Hz bandwidth is possible. This level of resolution is over an order of magnitude greater than what is now commercially available. A front panel switch can reduce the bandwidth to 2.5 Hz and attain a resolution of 0.025 (mu) in. This level of resolution meets or exceeds that of displacement measuring laser interferometry or capacitance gauge systems. Contact displacement measurement offers high part spatial resolution and therefore can measure not only part contour but surface finish. Capacitance gauges and displacement laser interferometry offer poor part spatial resolution and can not provide good surface finish measurements. Machine tool builders, meteorologists and quality inspection departments can immediately utilize the higher accuracy and capabilities that this amplifier offers. The precision manufacturing industry can improve as a result of improved capability to measure parts that help reduce costs and minimize material waste.

Hopkins, D. J.

1994-04-01

456

Direct solar-pumped iodine laser amplifier  

NASA Technical Reports Server (NTRS)

A XeCl laser which was developed earlier for an iodine laser oscillator was modified in order to increase the output pulse energy of XeCl laser so that the iodine laser output energy could be increased. The electrical circuit of the XeCl laser was changed from a simple capacitor discharge circuit of the XeCl laser to a Marx system. Because of this improvement the output energy from the XeCl laser was increased from 60 mj to 80 mj. Subsequently, iodine laser output energy was increased from 100 mj to 3 mj. On the other hand, the energy storage capability and amplification characteristics of the Vortek solar simulator-pumped amplifier was calculated expecting the calculated amplification factor is about 2 and the energy extraction efficiency is 26 percent due to the very low input energy density to the amplifier. As a result of an improved kinetic modeling for the iodine solar simulator pumped power amplifier, it is found that the I-2 along the axis of the tube affects seriously the gain profile. For the gas i-C3F7I at the higher pressures, the gain will decrease due to the I-2 as the pumping intensity increases, and at these higher pressures an increase in flow velocity will increase the gain.

Han, Kwang S.; Hwang, In H.; Stock, Larry V.

1988-01-01

457

LLNL/Lion Precision LVDT amplifier  

SciTech Connect

A high-precision, low-noise, LVDT amplifier has been developed which is a significant advancement on the current state of the art in contact displacement measurement. This amplifier offers the dynamic range of a typical LVDT probe but with a resolution that rivals that of non contact displacement measuring systems such as capacitance gauges and laser interferometers. Resolution of 0.1 {mu} in with 100 Hz bandwidth is possible. This level of resolution is over an order of magnitude greater than what is now commercially available. A front panel switch can reduce the bandwidth to 2.5 Hz and attain a resolution of 0.025 {mu} in. This level of resolution meets or exceeds that of displacement measuring laser interferometry or capacitance gauge systems. Contact displacement measurement offers high part spatial resolution and therefore can measure not only part contour but surface finish. Capacitance gauges and displacement laser interferometry offer poor part spatial resolution and can not provide good surface finish measurements. Machine tool builders, meteorologists and quality inspection departments can immediately utilize the higher accuracy and capabilities that this amplifier offers. The precision manufacturing industry can improve as a result of improved capability to measure parts that help reduce costs and minimize material waste.

Hopkins, D.J.

1994-04-01

458

Characterization of a Common-Gate Amplifier Using Ferroelectric Transistors  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

459

Characterization of a Common-Source Amplifier Using Ferroelectric Transistors  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

460

Experimental study of multipass copper vapour laser amplifiers  

SciTech Connect

Repetitively pulsed multipass copper vapour amplifiers are studied experimentally. A considerable increase in the peak power of laser pulses was achieved by using a special scheme of the amplifier. It is found that the main reasons preventing an increase in the peak power during many passages of the beam are the competitive development of lasing from spontaneous seeds in a parasitic resonator formed by the fold mirrors of a multipass amplifier, a decrease in the amplification during the last passages, and an increase in the pulse width at the amplifier output. (lasers. amplifiers)

Karpukhin, Vyacheslav T; Malikov, Mikhail M [Scientific Association for High Temperatures, Russian Academy of Sciences, Moscow (Russian Federation)

2008-12-31

461

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

NASA Astrophysics Data System (ADS)

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

Young, J. A.; Borror, S.; Obst, A. W.; Payton, J. R.; Seifter, A.

2005-08-01

462

An amplified fluorescence detection of T4 polynucleotide kinase activity based on coupled exonuclease III reaction and a graphene oxide platform.  

PubMed

A novel amplified fluorescence graphene oxide (GO) sensing platform for sensitive detection of T4 polynucleotide kinase (PNK) activity and inhibition was developed based on the exonuclease III (ExoIII) reaction. The efficient digestion capacity of ExoIII and the super quenching ability of GO both contribute to the detection sensitivity. PMID:25672549

Sun, Ni-Na; Kong, Rong-Mei; Qu, Fengli; Zhang, Xiaobing; Zhang, Shufang; You, Jinmao

2015-03-01

463

Quartz crystal microbalance detection of protein amplified by nicked circling, rolling circle amplification and biocatalytic precipitation.  

PubMed

A novel quartz crystal microbalance (QCM) assay was described for sensitive detection of protein. Lysozyme was used as a model of protein. To enhance the sensitivity of this QCM biosensor, biocatalytic precipitation (BCP) reaction combined with strand-scission cycle and rolling circle amplification (RCA) were applied together for the first time. As a result of the multi-signal amplification in this aptasensor, the detection limit for lysozyme was down to 0.3fM. What is more, this amplified QCM biosensor also showed good selectivity and practical usage in human serum. PMID:25461179

Zhang, Xiaoru; Chen, Jiao; Liu, Hongxia; Zhang, Shusheng

2014-10-31

464

Holding Charge  

NSDL National Science Digital Library

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

Eric Muller

1995-01-01

465

K-band FET amplifier for satellite downlink  

NASA Technical Reports Server (NTRS)

State-of-the-art performance is demonstrated with solid-state amplifiers in K-band. The amplifier provides 8.2 watts of power with 39 dB gain over a frequency band of 1.4 GHz. Nonlinearity analyses of solid-state amplifiers suggest that system performance can be improved significantly by using an FET amplifier. Preliminary investigations reveal that the solid-state amplifiers can be space-qualified and can be expected to replace the TWTA in many communication links in the near future. It is pointed out that with improvements in device technology, the power, bandwidth and efficiency of solid-state amplifiers using FETs can be further improved. With FETs operating at a junction temperature of less than 125 C, solid-state amplifiers are inherently reliable, indicating a ten-year mean time to failure.

Goel, J.; Cheung, R. P.

1984-01-01

466

Radiation effects on fiber amplifiers: design of radiation tolerant Yb/Er-based devices  

NASA Astrophysics Data System (ADS)

Rare-earth doped optical fibers have been shown to be very sensitive to radiations, limiting the integration of fiber-based systems in space missions. In this paper, we present the characterization of two amplifiers based on a set of prototype active Erbium/Ytterbium codoped double clad fibers developed by Ixfiber SAS. One of these fibers has been codoped with cerium inside its core to enhance its radiation tolerance whereas the other is a classical phosphosilicate Er/Yb fiber. The two amplifiers based on these fibers have been exposed to ?-rays at a low dose rate (0.3 rad/s) and to doses up to 90 krad. Previous studies indicated that Er/Yb amplifiers using this type of fiber suffered significant degradation for cumulated dose above 5-10 krad. We observed, on the contrary, that with our radiation hardened fiber, the degradation of the fiber amplifier's output power can be limited to less than 30% after an exposure dose of ~90 krad.

Girard, Sylvain; Laurent, Arnaud; Vivona, Marilena; Marcandella, Claude; Robin, Thierry; Cadier, Benoît; Boukenter, Aziz; Ouerdane, Youcef

2011-02-01

467

Src Mutation Induces Acquired Lapatinib Resistance in ERBB2-Amplified Human Gastroesophageal Adenocarcinoma Models  

PubMed Central

ERBB2-directed therapy is now a routine component of therapy for ERBB2-amplified metastatic gastroesophageal adenocarcinomas. However, there is little knowledge of the mechanisms by which these tumors develop acquired resistance to ERBB2 inhibition. To investigate this question we sought to characterize cell line models of ERBB2-amplified gastroesophageal adenocarcinoma with acquired resistance to ERBB2 inhibition. We generated lapatinib-resistant (LR) subclones from an initially lapatinib-sensitive ERBB2-amplified esophageal adenocarcinoma cell line, OE19. We subsequently performed genomic characterization and functional analyses of resistant subclones with acquired lapatinib resistance. We identified a novel, acquired SrcE527K mutation in a subset of LR OE19 subclones. Cells with this mutant allele harbour increased Src phosphorylation. Genetic and pharmacologic inhibition of Src resensitized these subclones to lapatinib. Biochemically, Src mutations could activate both the phosphatidylinositol 3-kinase and mitogen a