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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

Charge amplifier with bias compensation  

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)

2002-01-01

3

Improved current and charge amplifiers for driving piezoelectric loads  

E-print Network

Improved current and charge amplifiers for driving piezoelectric loads Andrew J. Fleming and S. O, Callaghan 2308, Australia. ABSTRACT Piezoelectric transducers are known to exhibit less hysterisis when, Piezoelectric, Capacitive, Load, Amplifier, Zero Offset, Compliance, Feedback 1. INTRODUCTION Piezoelectric

Fleming, Andrew J.

4

Reduction of fiber-nonlinearity-enhanced amplifier noise by means of phase-sensitive amplifiers.  

PubMed

In optical fiber transmission systems near the zero-dispersion wavelength that use in-line erbium-doped fiber amplifiers (EDFA's), the enhancement of optical amplifier noise caused by four-wave mixing (FWM) in transmission fibers degrades signal-to-noise ratio (SNR) excessively. We theoretically show that the enhancement of amplifier noise by the FWM in transmission fibers can be effectively eliminated by implementing in-line phase-sensitive amplifiers (PSA's). Small-signal analysis of the nonlinear Schrödinger equation shows that the transmission distance limited by the SNR of an in-line PSA system is expanded four times more than that of an in-line EDFA system. PMID:18183093

Imajuku, W; Takada, A

1997-01-01

5

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

SciTech Connect

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

Dooling, J. C.

1998-10-12

6

In-line phase sensitive amplifier based on PPLN waveguides.  

PubMed

We demonstrate a ?(2)-based in-line PSA with a carrier-recovery and phase-locking system for a phase shift keying (PSK) signal. By doubling the signal phase using a wavelength conversion technique, the carrier was recovered from a PSK signal. The carrier phase was synchronized to a local oscillator using optical injection locking. Phase sensitive amplification with a wide phase sensitive dynamic range of 20 dB was achieved using degenerate parametric amplification in a periodically poled LiNbO(3) (PPLN) waveguide. The phase regeneration effect was examined for a degraded signal by means of constellation analyses and bit-error rate measurements. The in-line PSA also operated successfully as a repeater amplifier in a 160 km fiber link without a power penalty. Finally, we demonstrate the regeneration of non-linear impairments induced by fiber non-linearity. PMID:23736428

Umeki, Takeshi; Asobe, Masaki; Takenouchi, Hirokazu

2013-05-20

7

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

ERIC Educational Resources Information Center

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

Temple, Paul A.

1975-01-01

8

High sensitivity chemically amplified EUV resists through enhanced EUV absorption  

NASA Astrophysics Data System (ADS)

Resolution, line edge roughness, sensitivity and low outgassing are the key focus points for extreme ultraviolet (EUV) resist materials. Sensitivity has become increasingly important so as to address throughput concerns in device manufacturing and compensate for the low power of EUV sources. Recent studies have shown that increasing the polymer linear absorption absorption coefficient in EUV resists translates to higher acid generation efficiency and good pattern formation. In this study, novel high absorbing polymer platforms are evaluated. The contributing effect of the novel absorbing chromophore to the resultant chemically amplified photoresist is evaluated and compared with a standard methacrylate PAG Bound Polymer (PBP) platform. We report that by increasing EUV absorption, we cleanly resolved 17 nm 1:1 line space can be achieved at a sensitivity of 14.5 mJ/cm2, which is consistent with dose requirements dictated by the ITRS roadmap. We also probe the effect of fluorinated small molecule additives on acid yield generation (Dil C) at EUV of a PBP platform.

Ongayi, Owendi; Christianson, Matthew; Meyer, Matthew; Coley, Suzanne; Valeri, David; Kwok, Amy; Wagner, Mike; Cameron, Jim; Thackeray, Jim

2012-03-01

9

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

10

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

Microsoft Academic Search

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

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

1998-01-01

11

Charge PreAmplifier Functionality in Gas Electron Multiplier Digital Hadron Calorimeter at UTA  

Microsoft Academic Search

A digital hadron calorimeter (DHCAL) is a sampling calorimeter that could provide the necessary jet energy resolution for International Linear Collider physics when used with the Particle Flow Algorithms (PFA). UTA's High Energy Physics (HEP) group has been developing a DHCAL using Gas Electron Multiplier (GEM) technology. GEM amplifies energy deposit from traversing charged particles using a high electric field

Heather Brown; Changhie Hahn; Wonjeong Kim; Jia Li; Carlos Medina; Akihiro Nozawa; Jacob Smith; Andy White; Jaehoon Yu

2006-01-01

12

Neutron cross section sensitivity for minor actinide transmutation in energy amplifier systems  

Microsoft Academic Search

The nuclear data sensitivity in 3D Monte Carlo burnup calculations of minor actinide transmutation in Energy Amplifier Systems is assessed. Ansaldo Nucleare’s 80MWth Energy Amplifier Demonstration Facility (EADF) design serves as a technical and geometrical platform for the analysis. The accelerator-driven EADF is a fast, subcritical system based on classical MOX-fuel technology and on molten lead–bismuth eutectic cooling. For Monte

Marcus Dahlfors; Yacine Kadi; Adonai Herrera-Martínez

2007-01-01

13

Superoxide dismutase amplifies organismal sensitivity to ionizing radiation  

SciTech Connect

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

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

1989-02-15

14

Normal Hearing Sensitivity at Low-to-Middle Frequencies with 34% Prestin-Charge Density  

PubMed Central

The mammalian outer hair cells (OHCs) provide a positive mechanical feedback to enhance the cochlea's hearing sensitivity and frequency selectivity. Although the OHC-specific, somatic motor protein prestin is required for cochlear amplification, it remains unclear whether prestin can provide sufficient cycle-by-cycle feedback. In cochlear mechanical modeling, varying amounts of OHC motor activity should provide varying degrees of feedback efficiency to adjust the gain of cochlear amplifier at resonant frequencies. Here we created and characterized two new prestin-hypomorphic mouse models with reduced levels of wild-type prestin. OHCs from these mice exhibited length, total elementary charge movement (Qmax), charge density, and electromotility intermediate between those of wild-type and prestin-null mice. Remarkably, measurements of auditory brainstem responses and distortion product otoacoustic emissions from these mice displayed wild-type like hearing sensitivities at 4–22 kHz. These results indicate that as low as 26.7% Qmax, 34.0% charge density and 44.0% electromotility in OHCs were sufficient for wild-type-like hearing sensitivity in mice at 4–22 kHz, and that these in vitro parameters of OHCs did not correlate linearly with the feedback efficiency for in vivo gain of the cochlear amplifier. Our results thus provide valuable data for modeling cochlear mechanics and will stimulate further mechanistic analysis of the cochlear amplifier. PMID:23029017

Yamashita, Tetsuji; Fang, Jie; Gao, Jiangang; Yu, Yiling; Lagarde, Marcia Mellado; Zuo, Jian

2012-01-01

15

Catalytic and Molecular Beacons for Amplified Detection of Metal Ions and Organic Molecules with High Sensitivity  

PubMed Central

Catalytic beacon has emerged as a general platform for sensing metal ions and organic molecules. However, few reports have taken advantage of the true potential of catalytic beacons in signal amplification through multiple enzymatic turnovers, as existing designs require either equal concentrations of substrate and DNAzyme or an excess of DNAzyme in order to maintain efficient quenching, eliminating the excess of substrate necessary for multiple turnovers. Based on the large difference in the melting temperatures between the intramolecular molecular beacon stem and intermolecular products of identical sequences, we here report a general strategy of catalytic and molecular beacon (CAMB) that combines the advantages of the molecular beacon for highly efficient quenching with the catalytic beacon for amplified sensing through enzymatic turnovers. Such a CAMB design allows detection of metal ions such as Pb2+ with a high sensitivity (LOD=600 pM). Furthermore, aptamer sequence has been introduced into DNAzyme to use the modified CAMB for amplified sensing of adenosine with similar high sensitivity. These results together demonstrate that CAMB provides a general platform for amplified detection of a wide range of targets. PMID:20481627

Zhang, Xiao-Bing; Wang, Zidong; Xing, Hang; Xiang, Yu; Lu, Yi

2010-01-01

16

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

SciTech Connect

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

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

1998-06-24

17

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

18

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

19

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

20

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

PubMed Central

Cortical–striatal circuit dysfunction in mental illness may enhance addiction vulnerability. Neonatal ventral hippocampal lesions (NVHL) model this dual diagnosis causality by producing a schizophrenia syndrome with enhanced responsiveness to addictive drugs. Rat genome-wide microarrays containing >24 000 probesets were used to examine separate and co-occurring effects of NVHLs and cocaine sensitization (15 mg/kg/day × 5 days) on gene expression within medial prefrontal cortex (MPFC), nucleus accumbens (NAC), and caudate-putamen (CAPU). Two weeks after NVHLs robustly amplified cocaine behavioral sensitization, brains were harvested for genes of interest defined as those altered at P < 0.001 by NVHL or cocaine effects or interactions. Among 135 genes so impacted, NVHLs altered twofold more than cocaine, with half of all changes in the NAC. Although no genes were changed in the same direction by both NVHL and cocaine history, the anatomy and directionality of significant changes suggested synergy on the neural circuit level generative of compounded behavioral phenotypes: NVHL predominantly downregulated expression in MPFC and NAC while NVHL and cocaine history mostly upregulated CAPU expression. From 75 named genes altered by NVHL or cocaine, 27 had expression levels that correlated significantly with degree of behavioral sensitization, including 11 downregulated by NVHL in MPFC/NAC, and 10 upregulated by NVHL or cocaine in CAPU. These findings suggest that structural and functional impoverishment of prefrontal-cortical-accumbens circuits in mental illness is associated with abnormal striatal plasticity compounding with that in addictive disease. Polygenetic interactions impacting neuronal signaling and morphology within these networks likely contribute to addiction vulnerability in mental illness. PMID:23682998

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

2014-01-01

21

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

PubMed

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

Granata, C; Vettoliere, A; Russo, M

2011-01-01

22

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

NASA Astrophysics Data System (ADS)

An integrated ultrahigh sensitive current amplifier based on a niobium dc superconducting quantum interference device (SQUID) has been developed. The sensor design is based on a multiturn signal coil coupled to a suitable SQUID magnetometer. The signal coil consists of 60 square niobium turns tightly coupled to a superconducting flux transformer of a SQUID magnetometer. The primary coil (pick-up coil) of the flux transformer has been suitably designed in order to accommodate the multiturn input coil. It has a side length of 10 mm and a width of 2.4 mm. In such a way we have obtained a signal current to magnetic flux transfer coefficient (current sensitivity) as low as 62 nA/?0. The sensor has been characterized in liquid helium by using a direct coupling low noise readout electronic and a standard modulated electronic in flux locked loop configuration for the noise measurements. Beside the circuit complexity, the sensor has exhibited a smooth and free resonance voltage-flux characteristic guaranteeing a reliable and a stable working operation. Considering a SQUID magnetic flux noise of S?1/2 = 1.8 ??0/Hz1/2 at T = 4.2 K, a current noise as low as 110 fA/Hz1/2 is obtained. Such a value is about a factor two less than the noise of other SQUIDs of the same category. As an application, Nyquist noise measurements of integrated test resistors using the current sensing noise thermometer technique are reported. Due to its high performance such a sensor can be employed in all applications requiring an extremely current sensitivity like the readout of the gravitational wave detectors and the current sensing noise thermometry.

Granata, C.; Vettoliere, A.; Russo, M.

2011-01-01

23

Flavopiridol inhibits soft tissue sarcoma growth with preferential sensitivity in a CDK4 gene amplified subtype  

Microsoft Academic Search

Introduction: Current chemotherapy for advanced soft tissue sarcoma (STS) has low overall response rates. It has been shown that the CDK4 gene is frequently amplified in some STS subtypes. Here we tested flavopiridol, a pan cyclin dependent kinase inhibitor, with STS subtypes that have amplified (dedifferentiated liposarcoma, DDLS) or non-amplified (malignant peripheral nerve sheath tumor, MPNST) CDK4.Methods: DDLS and MPNST

Elliot B. Sambol; Peter T. Kennealey; Monica Motwani; Jin-Hong Chen; Haider Cheema; Margaret Leversha; Gary K. Schwartz; Samuel Singer

2004-01-01

24

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

PubMed

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

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

2013-10-11

25

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

PubMed

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

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

2013-06-01

26

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

PubMed

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

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

2014-10-01

27

Noise performance of optical fiber transmission links that use non-degenerate cascaded phase-sensitive amplifiers.  

PubMed

Based on semi-classical theory, the noise performance of a multi-span fiber optical transmission system employing a cascaded phase-insensitive amplifier (PIA) and phase-sensitive amplifiers (PSAs) is investigated. Compared with the pure-PIA and pure-PSA based in-line amplification schemes, the copier + PSA scheme is found to improve the system NF by up to 6 and 3 dB, respectively, in an optimized long-haul fiber link. In addition, this cascaded configuration will significantly relax the requirement for accurate phase- and wavelength-locking which is rigorously needed in the pure-PSA configuration. This scheme is also modulation-format independent. As a proof of concept, the NF of a fiber parametric amplifier based copier + PSA cascade with inter-stage attenuation representing the fiber link is measured, which shows a 1.8-dB total NF improvement over the conventional EDFA cascade. PMID:20720922

Tong, Zhi; McKinstrie, C J; Lundström, Carl; Karlsson, Magnus; Andrekson, Peter A

2010-07-19

28

Charge amplification concepts for direction-sensitive dark matter detectors  

E-print Network

Direction measurement of weakly interacting massive particles in time-projection chambers can provide definite evidence of their existence and help to determine their properties. This article demonstrates several concepts for charge amplification in time-projection chambers that can be used in direction-sensitive dark matter search experiments. We demonstrate reconstruction of the 'head-tail' effect for nuclear recoils above 100keV, and discuss the detector performance in the context of dark matter detection and scaling to large detector volumes.

D. Dujmic; P. Fisher; G. Sciolla; S. Ahlen; V. Dutta; S. Henderson; A. Kaboth; G. Kohse; R. Lanza; J. Monroe; A. Roccaro; N. Skvorodnev; H. Tomita; R. Vanderspek; H. Wellenstein; R. Yamamoto

2008-04-30

29

Spatial modes of phase-sensitive parametric image amplifiers with circular and elliptical Gaussian pumps.  

PubMed

We develop a method for finding the number and shapes of the independently squeezed or amplified modes of a spatially-broadband, travelling-wave, frequency- and polarization-degenerate optical parametric amplifier in the general case of an elliptical Gaussian pump. The obtained results show that for tightly focused pump only one mode is squeezed, and this mode has a Gaussian TEM(00) shape. For larger pump spot sizes that support multiple modes, the shapes of the most-amplified modes are close to Hermite- or Laguerre-Gaussian profiles. These results can be used to generate matched local oscillators for detecting high amounts of squeezing and to design parametric image amplifiers that introduce minimal distortion. PMID:22274255

Annamalai, Muthiah; Stelmakh, Nikolai; Vasilyev, Michael; Kumar, Prem

2011-12-19

30

Sensitive and selective amplified visual detection of cytokines based on exonuclease III-aided target recycling.  

PubMed

A new Exo III assisted strand-cleavage cycle and ligand-responsive quadruplex formation strategy for amplified and label-free detection of IFN-? was reported with a detection limit of 0.1 pM and a visual detection limit of 20 pM by the naked eye. PMID:25231197

Zhang, Kai; Ren, Tianli; Wang, Ke; Zhu, Xue; Wu, Hao; Xie, Minhao

2014-11-11

31

Reconstruction of a multimode entangled state using a two-photon phase-sensitive linear amplifier  

SciTech Connect

We propose a model for the measurement of an arbitrary multimode entangled state of the cavity field using two-photon correlated emission laser. We consider two cases: (a) The modes have different frequencies and are detected separately and (b) the modes consist of two orthogonal polarization states and are detected using a single balanced homodyne detector. The basic idea is to amplify the initial multimode state such that there is no-noise in the quadrature of interest and all the noise is fed into the conjugate quadrature component. The amplified noise-free quadrature is prepared in different phases and then corresponding quadrature distribution is measured. The Wigner function of the initial multimode entangled state is then reconstructed by using inverse Radon transformation. This scheme is insensitive to the noise associated with the nonunit efficiency of the detector in the homodyne detection measurement scheme.

Ahmad, Mashhood [Department of Electronics, Quaid-i-Azam University, Islamabad (Pakistan); Qamar, Shahid [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad (Pakistan); Zubairy, M. Suhail [Department of Electronics, Quaid-i-Azam University, Islamabad (Pakistan); Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States)

2003-04-01

32

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

33

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

PubMed Central

We report on the development of an enzyme-amplified sandwich-type immunosensor based on a thin gold film sputtered on an anodic nanoporous niobium oxide (Au@Nb2O5) electrode. The electrocatalytic activity of enzymatically amplified electroactive species and a stable electrode consisting of Au@Nb2O5 were used to obtain a powerful signal amplification of the electrochemical immunobiosensor. The method using this electrochemical biosensor based on an Au@Nb2O5 electrode provides a much better performance than those based on conventional bulk gold or niobium oxide electrodes. Our novel approach does not require any time-consuming cleaning steps to yield reproducible electrochemical signals. In addition, the strong adhesion of gold films on the niobium oxide electrodes offers a very stable substrate during electrochemical biosensing. Cyclic voltammetry measurements indicate that non-specific binding of proteins to the modified Au@Nb2O5 surface is sufficiently low to be ignored in the case of our novel system. Finally, we demonstrated the ability of the biosensor based on an Au@Nb2O5 offering the enhanced performance with a high resolution and sensitivity. Therefore, it is expected that the biosensor based on an Au@Nb2O5 has great potential for highly efficient biological devices. PMID:22399928

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

2010-01-01

34

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

PubMed Central

Kirsten RAS (KRAS) is a small GTPase that plays a key role in Ras/mitogen-activated protein kinase signaling; somatic mutations in KRAS are frequently found in many cancers. The most common KRAS mutations result in a constitutively active protein. Accurate detection of KRAS mutations is pivotal to the molecular diagnosis of cancer and may guide proper treatment selection. Here, we describe a two-step KRAS mutation screening protocol that combines whole-genome amplification (WGA), high-resolution melting analysis (HRM) as a prescreen method for mutation carrying samples, and direct Sanger sequencing of DNA from formalin-fixed, paraffin-embedded (FFPE) tissue, from which limited amounts of DNA are available. We developed target-specific primers, thereby avoiding amplification of homologous KRAS sequences. The addition of herring sperm DNA facilitated WGA in DNA samples isolated from as few as 100 cells. KRAS mutation screening using high-resolution melting analysis on wgaDNA from formalin-fixed, paraffin-embedded tissue is highly sensitive and specific; additionally, this method is feasible for screening of clinical specimens, as illustrated by our analysis of pancreatic cancers. Furthermore, PCR on wgaDNA does not introduce genotypic changes, as opposed to unamplified genomic DNA. This method can, after validation, be applied to virtually any potentially mutated region in the genome. PMID:19959798

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

2010-01-01

35

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

E-print Network

gain of 50 V/ A for a cryogenic 1 M load resistor. The performance of this amplifier is already the past decade due to its high charge sensitivity. This charge sensitivity has already been utilized demonstrate that we can measure the current through a cryogenic 1 M load resistor with a transimped- ance gain

Segall, Ken

36

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

37

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

PubMed Central

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

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

2012-01-01

38

SEU critical charge and sensitive area in a submicron CMOS technology  

SciTech Connect

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

Detcheverry, C.; Dachs, C.; Lorfevre, E.; Sudre, C.; Bruguier, G.; Palau, J.M.; Gasiot, J. [Univ. Montpellier II (France)] [Univ. Montpellier II (France); Ecoffet, R. [CNES, Toulouse (France)] [CNES, Toulouse (France)

1997-12-01

39

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

40

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

E-print Network

droplets with submicron to micron sizes. Emulsions are used in food, cosmetics, medicine, coatings, paints principle for many industrial and practical processes. Using micrometer-sized pH-sensitive poly- meric hydrogel particles as emulsion stabilizers, we prepare emul- sions that consist of oppositely charged

41

Short communication: Naturally sensitive Bacillus thuringiensis EG10368 produces thurincin H and acquires immunity after heterologous expression of the one-step-amplified thurincin H gene cluster.  

PubMed

Heterologous expression of bacteriocin genetic determinants (or operons) has long been a research interest for the functional analysis of genes involved in bacteriocin biosynthesis, regulation, modification, and immunity. Previously, construction of genomic libraries of the bacteriocin producer strains was usually required to identify new bacteriocin operons, a method that is tedious and time consuming. For the first time, we directly amplified an 8.14-kb bioinformatically identified thurincin H gene cluster using a one-step PCR method with 100% accuracy. This amplified gene cluster was cloned into plasmid pHT315, resulting in plasmid pGW139, and subsequently transformed to Bacillus thuringiensis EG10368, a strain naturally sensitive to thurincin H. Heterologous expression of the gene cluster makes the sensitive B. thuringiensis EG10368 produce thurincin H at a higher level compared with the wild-type producer, B. thuringiensis SF361. Moreover, B. thuringiensis EG10368pGW139 acquired complete immunity to thurincin H. The results indicated that one-step PCR is a promising tool to accurately amplify long bacteriocin gene clusters used in bacteriocin functional analysis studies and it is an effective way to produce bacteriocins at a higher level, without the need to clone large chromosomal fragments. PMID:24767890

Wang, G; Manns, D C; Churey, J J; Worobo, R W

2014-07-01

42

Fibre Amplifiers  

NASA Astrophysics Data System (ADS)

The chapter gives a detailed treatment of erbium-doped fiber amplifiers (EDFA), Raman amplifiers, and parametric amplifiers. Each section comprises the fundamentals including the basic physics and relevant in-depth theoretical modeling, amplifier characteristics and performance data as a function of specific operation parameters. Typical applications in fiber-optic communication systems and the improvements achievable through the use of fiber amplifiers are illustrated.

Rottwitt, Karsten

43

Electronic amplifiers: A compilation  

NASA Technical Reports Server (NTRS)

Several types of amplifiers and amplifier systems are considered. These include preamplifiers, high power amplifiers, buffer and isolation amplifiers, amplifier circuits, and general purpose amplifiers.

1971-01-01

44

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

45

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

46

A fluorescence aptasensor based on DNA charge transport for sensitive protein detection in serum.  

PubMed

A novel fluorescence aptasensor based on DNA charge transport for sensitive protein detection has been developed. A 15nt DNA aptamer against thrombin was used as a model system. The aptamer was integrated into a double strand DNA (dsDNA) that was labeled with a hole injector, naphthalimide (NI), and a fluorophore, Alexa532, at its two ends. After irradiation by UV light, the fluorescence of Alexa532 was bleached due to the oxidization of Alexa532 by the positive charge transported from naphthalimide through the dsDNA. In the presence of thrombin, the binding of thrombin to the aptamer resulted in the unwinding of the dsDNA into ssDNA, which led to the blocking of charge transfer and the strong fluorescence emission of Alexa532. By monitoring the fluorescence signal change, we were able to detect thrombin in homogeneous solutions with high selectivity and high sensitivity down to 1.2 pM. Moreover, as DNA charge transfer is resistant to interferences from biological contexts, the aptasensor can be used directly in undiluted serum with similar sensitivity as that in buffer. This new sensing strategy is expected to promote the exploitation of aptamer-based biosensors for protein assays in complex biological matrixes. PMID:21949940

Zhang, Xinyue; Zhao, Zilong; Mei, Hongcheng; Qiao, Yupu; Liu, Qiaoling; Luo, Wangxi; Xia, Tie; Fang, Xiaohong

2011-11-21

47

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 4min. The limits of detection for Lys, Tau, and NA were 0.25, 0.50, and 0.20nM (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

48

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

49

Charge Transport in Dye-Sensitized Solar Cells Based on Flame-made Nanoparticles  

Microsoft Academic Search

The fundamental understanding on charge-transport properties of flame-synthesized in dye-sensitized solar cells (DSSCs) is established in this work. By employing a one-step flame spray pyrolysis (FSP), predominantly anatase TiO2 nanoparticles with average nanoparticle sizes between 11 and 36 nm were achieved by varying the rate of combustion enthalpy (through varying liquid precursor feed flow rates) and using either an “open-flame”

George Tsekouras; Masanori Miyashita; Yung Kent Kho; Wey Yang Teoh; Attila Janos Mozer; Rose Amal; Shogo Mori; Gordon G. Wallace

2010-01-01

50

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

51

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

PubMed

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

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

2013-06-26

52

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

53

Charge transport through split photoelectrodes in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

54

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

55

Boosting the efficiency of quantum dot sensitized solar cells through modulation of interfacial charge transfer.  

PubMed

The demand for clean energy will require the design of nanostructure-based light-harvesting assemblies for the conversion of solar energy into chemical energy (solar fuels) and electrical energy (solar cells). Semiconductor nanocrystals serve as the building blocks for designing next generation solar cells, and metal chalcogenides (e.g., CdS, CdSe, PbS, and PbSe) are particularly useful for harnessing size-dependent optical and electronic properties in these nanostructures. This Account focuses on photoinduced electron transfer processes in quantum dot sensitized solar cells (QDSCs) and discusses strategies to overcome the limitations of various interfacial electron transfer processes. The heterojunction of two semiconductor nanocrystals with matched band energies (e.g., TiO(2) and CdSe) facilitates charge separation. The rate at which these separated charge carriers are driven toward opposing electrodes is a major factor that dictates the overall photocurrent generation efficiency. The hole transfer at the semiconductor remains a major bottleneck in QDSCs. For example, the rate constant for hole transfer is 2-3 orders of magnitude lower than the electron injection from excited CdSe into oxide (e.g., TiO(2)) semiconductor. Disparity between the electron and hole scavenging rate leads to further accumulation of holes within the CdSe QD and increases the rate of electron-hole recombination. To overcome the losses due to charge recombination processes at the interface, researchers need to accelerate electron and hole transport. The power conversion efficiency for liquid junction and solid state quantum dot solar cells, which is in the range of 5-6%, represents a significant advance toward effective utilization of nanomaterials for solar cells. The design of new semiconductor architectures could address many of the issues related to modulation of various charge transfer steps. With the resolution of those problems, the efficiencies of QDSCs could approach those of dye sensitized solar cells (DSSC) and organic photovoltaics. PMID:22493938

Kamat, Prashant V

2012-11-20

56

Cation-controlled interfacial charge injection in sensitized nanocrystalline TiO{sub 2}  

SciTech Connect

The photophysical and photoelectrochemical properties of Ru(deeb)(bpy){sub 2}(PF{sub 6}){sub 2}, where bpy is 2,2{prime}-bipyridine and deeb is 4,4{prime}-(CODEt){sub 2}-2,2{prime}-bipyridine, anchored to nanocrystalline TiO{sub 2}(anatase) or ZrO{sub 2} films are reported. In neat acetonitrile (or 0.1 M tetrabutylammonium perchlorate) long-lived metal-to-ligand charge transfer (MLCT) excited states are observed on both TiO{sub 2} and ZrO{sub 2}. Addition of LiClO{sub 4} results in a red shift in the MLCT absorption and photoluminescence, PL, spectra on both TiO{sub 2} and ZrO{sub 2}, and a concentration-dependent quenching of the PL intensity on TiO{sub 2}. The Li{sup +}-induced spectroscopic changes were found to be reversible by varying the electrolyte composition. Time-resolved adsorption measurements demonstrate that the presence of lithium cations increases the quantum yield for interfacial charge separation with no discernible influence on the rate of charge recombination. A second-order kinetic model quantified charge recombination transients. A model is proposed wherein Li{sup +} ion adsorption stabilizes TiO{sub 2} acceptor sites resulting in energetically more favorable interfacial electron transfer. The generality of this model was explored with different electrolytes and sensitizers. In regenerative solar cells, the addition of Li{sup +} increases both the efficiency and long wavelength sensitivity of the cell.

Kelly, C.A.; Farzad, F.; Thompson, D.W.; Stipkala, J.M.; Meyer, G.J.

1999-09-28

57

Composite tin and zinc oxide nanocrystalline particles for enhanced charge separation in sensitized degradation of dyes.  

PubMed

Composite ZnO/SnO2 catalyst has been studied for the sensitized degradation of dyes e.g. Eosin Y (2', 4', 5', 7'-tetrabromofluorescein disodium salt) in relation to efficient charge separation properties of the catalyst. Improved photocatalytic activity was observed in the case of ZnO/SnO2 composite catalyst compared to the catalytic activity of ZnO, SnO2 or TiO2 powder. The suppression of charge recombination in the composite ZnO/SnO2 catalyst led to higher catalytic activity for the degradation of Eosin Y. Degradation of Eosin follows concomitant formation of CO2 and formation of CO2 followed a pseudo-first-order rate. Photoelectrochemical cells constructed using SnO2, ZnO, ZnO/SnO2 sensitized with Eosin Y showed V(oc) of 175, 306, 512 mV/cm2 and I(sc) of 50, 70, 200 microA/cm2 respectively. A higher irreversible degradation of Eosin Y and higher V(oc) observed on composite ZnO/SnO2 than ZnO and SnO2 separately can be considered as a proof of enhanced charge separation of ZnO/SnO2 catalyst. Eosin Y showed a higher emission decreases on ZnO/SnO2 composite than on individual ZnO, SnO2 or TiO2 indicating dominance of the charge injection process. Photoinjected electrons are tunneled from ZnO to SnO2 particles accumulating injected electrons in the conduction bands allowing wider separation of excited carriers. PMID:12365841

Bandara, J; Tennakone, K; Jayatilaka, P P B

2002-10-01

58

1148 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 56, NO. 3, JUNE 2009 High Speed Multichannel Charge Sensitive  

E-print Network

. We present the concept and first experimental tests of fully par- allel 128-channel charge sensitive of Chemistry and Bio- chemistry, University of California at Los Angeles, Los Angeles, CA 90095 USA (e

Michalet, Xavier

59

Characterization of a New Charge Sensitive Preamplifier (CSP) for the Electromagnetic Calorimeters of the ALICE Experiment  

SciTech Connect

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

Wang, Yaping [Inst. of Particle Physics/Key Lab. of Quark and Lepton Physics, Central China Normal Univ., Wuhan, C; Muller, Hans [CERN, Geneva, Switzerland; Cai, Xu [Inst. of Particle Physics/Key Lab. of Quark and Lepton Physics, Central China Normal Univ., Wuhan, C; Zhou, Daicui [Inst. of Particle Physics/Key Lab. of Quark and Lepton Physics, Central China Normal Univ., Wuhan, C; Awes, Terry C [ORNL; Yin, Zhongbao [Inst. of Particle Physics/Key Lab. of Quark and Lepton Physics, Central China Normal Univ., Wuhan, C

2012-01-01

60

Improved Sensitivity Mass Spectrometric Detection of Eicosanoids by Charge Reversal Derivatization  

PubMed Central

Combined liquid chromatography–electrospray ionization-tandem mass spectrometry (LC–ESI-MS/MS) is a powerful method for the analysis of oxygenated metabolites of polyunsaturated fatty acids including eicosanoids. Here we describe the synthesis of a new derivatization reagent N-(4-aminomethylphenyl)pyridinium (AMPP) that can be coupled to eicosanoids via an amide linkage in quantitative yield. Conversion of the carboxylic acid of eicosanoids to a cationic AMPP amide improves sensitivity of detection by 10- to 20-fold compared to negative mode electrospray ionization detection of underivatized analytes. This charge reversal derivatization allows detection of cations rather than anions in the electrospray ionization mass spectrometer, which enhances sensitivity. Another factor is that AMPP amides undergo considerable collision-induced dissociation in the analyte portion rather than exclusively in the cationic tag portion, which allows isobaric derivatives to be distinguished by tandem mass spectrometry, and this further enhances sensitivity and specificity. This simple derivatization method allows pros-taglandins, thromboxane B2, leukotriene B4, hydroxyeicosatetraenoic acid isomers, and arachidonic acid to be quantified in complex biological samples with limits of quantification in the 200–900 fg range. One can anticipate that the AMPP derivatization method can be extended to other carboxylic acid analytes for enhanced sensitivity detection. PMID:20704368

Bollinger, James G.; Thompson, Wallace; Lai, Ying; Oslund, Rob C.; Hallstrand, Teal S.; Sadilek, Martin; Turecek, Frantisek; Gelb, Michael H.

2010-01-01

61

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

PubMed Central

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

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

2002-01-01

62

Operational Amplifiers.  

ERIC Educational Resources Information Center

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

Foxcroft, G. E.

1986-01-01

63

Development of a sensitive biotin-avidin amplified enzyme-linked immunosorbent assay for the determination of ketamine in biological samples.  

PubMed

An effective biotin-avidin amplified enzyme-linked immunosorbent assay (BA-ELISA) was developed to determine ketamine in biological samples. A conjugate of ketamine and ovalbumin (OVA) was used for immunization to produce polyclonal antibody. The conjugate of ketamine and bovine serum albumin (BSA) with polyclonal antibody was calculated to have an affinity constant (K(aff)) of 3.30 x 10(8)(mol/L)(-1). The linear range of ketamine was 0.1-1000 microg/L with recoveries from 89.6% to 99.9% in spiked sample analysis. The detection limit of ketamine was 0.03 microg/L, which is more sensitive than that of the traditional ELISA. The results obtained by BA-ELISA agreed well with that of the traditional ELISA, with a correlation coefficient of 0.98. PMID:20623407

Zhang, Wendi; Su, Ping; Yang, Yi; Guo, Zhenquan

2010-01-01

64

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

SciTech Connect

This report provides the background theory, user input, and sample problems required for the efficient application of the DEPTH-CHARGE system - a code block for both static and time-dependence perturbation theory and data sensitivity analyses. The DEPTH-CHARGE system is of modular construction and has been implemented within the VENTURE-BURNER computational system at Oak Ridge National Labortary. The DEPTH-CHARGE system provides, for the first time, a complete generalized first-order perturbation/sensitivity theory capability for both static and time-dependent analysis of realistic multidimensional reactor models.

White, J.R.

1981-09-01

65

Amplifier Distortion  

NASA Astrophysics Data System (ADS)

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

Keeports, David

2006-12-01

66

Sensitivity of the CSR self-interaction to the local longitudinal charge concentration of an electron bunch  

NASA Astrophysics Data System (ADS)

Recent measurements of the coherent synchrotron radiation (CSR) effects indicated that the observed emittance growth and energy modulation due to the orbit-curvature-induced bunch self-interaction are sometimes bigger than predictions based on Gaussian longitudinal charge distributions. In this paper, by performing a model study, we show both analytically and numerically that when the longitudinal bunch charge distribution involves concentration of charges in a small fraction of the bunch length, enhancement of the CSR self-interaction beyond the Gaussian prediction may occur. The level of this enhancement is sensitive to the level of the local charge concentration.

Li, R.

2001-12-01

67

Generation and Phase-Sensitive Manipulations of Pulsed Squeezed Light with Traveling-Wave Optical Parametric Amplifiers  

NASA Astrophysics Data System (ADS)

This dissertation investigates the optical field's behavior after propagation through multiple stages of nonlinear dielectric media in a free space traveling-wave configuration. The work is motivated by the quantum sensor program (QSP), a DARPA-sponsored effort to enhance the resolution of existing stand-off imaging sensors utilizing nonclassical states of the radiation field. One proposed resolution enhancement utilizes a combination of squeezed vacuum injection with optical phase-sensitive amplification. In this solution, attenuation of high spatial frequency content is mitigated by mixing a squeezed vacuum field with the returned signal, followed by optical phase-sensitive amplification to approach unity detection efficiency at high gains. While earlier experiments dealt with phenomena generated in a single optically nonlinear medium, this work focuses on the effects of multiple nonlinear crystals in a single beam's path. It shows that nonclassical states maintain their quantum features after interacting in an additional nonlinear stage. More specifically, this thesis describes the cascaded phase-sensitive amplification and de-amplification of both classical coherent states and quantum squeezed states, which collectively demonstrate that it is possible to address the negative effects of low-detection efficiencies and loss in the context of imaging. In addition, this thesis details the effects of an offset between the pump and signal beam waists along the propagation axis. Surprisingly, the optimal point for parametric interaction does not occur at zero offset, indicating the existence of a previously unknown tuning 'knob' which can be used for experimental optimization. Finally, note that all experiments utilize a single spatial mode as part of a larger experimental effort to demonstrate multi-mode image resolution enhancement.

Alon, Gideon

68

The FKBP38 Catalytic Domain Binds to Bcl-2 via a Charge-sensitive Loop  

PubMed Central

FKBP38 is a regulator of the prosurvival protein Bcl-2, but in the absence of detailed structural insights, the molecular mechanism of the underlying interaction has remained unknown. Here, we report the contact regions between Bcl-2 and the catalytic domain of FKBP38 derived by heteronuclear NMR spectroscopy. The data reveal that a previously identified charge-sensitive loop near the putative active site of FKBP38 is mainly responsible for Bcl-2 binding. The corresponding binding epitope of Bcl-2 could be identified via a peptide library-based membrane assay. Site-directed mutagenesis of the key residues verified the contact sites of this electrostatic protein/protein interaction. The derived structure model of the complex between Bcl-2 and the FKBP38 catalytic domain features both electrostatic and hydrophobic intermolecular contacts and provides a rationale for the regulation of the FKBP38/Bcl-2 interaction by Ca2+. PMID:22523079

Haupt, Katja; Jahreis, Gunther; Linnert, Miriam; Maestre-Martinez, Mitcheell; Malesevic, Miroslav; Pechstein, Arndt; Edlich, Frank; Lucke, Christian

2012-01-01

69

Carbon nanomaterials as charge collectors in dye sensitized solar cells and tandems  

NASA Astrophysics Data System (ADS)

This research has set out to understand the physical and electrochemical properties of carbon nanomaterials as charge collector, catalyst and energy transfer induced redox couple modifier in dye sensitized solar cells, which may one day be a major source of electric power generation. This research focuses on (1) characterizing the use of carbon nanotubes, both single walled and multi walled, as catalyst and charge carrier collector (2) improving the performance of the carbon nanotubes with modification by graphene, and various doping (3) testing 2-d carbon nanomaterials, such as graphene and few layer graphene nanoribbons, characterizing an interesting new side effect of photobleaching the iodide/triiodide redox couple, and (4) using the flexibility of dry spun carbon nanotubes sheets and carbon nanotubes sheets for tandem structures and novel fiber architecture. A major motivation in using carbon nanostructures in dye sensitized solar cells is that the standard dye solar cell uses platinum coated on a transparent conductive oxide as the counter electrode. Platinum, a rare and costly metal, is subject to scarcity issues. With proper application, the single walled carbon nanotubes mats could be used for as a substitute that would give efficiencies equivalent to the reference dye solar cells with platinum, and the dry spun multi-walled carbon nanotubes were capable of achieving performance equivalent to platinum with mild doping and nanomaterials additives. The novel architectural design work performed here used these multi-walled carbon nanotubes taken in the form of dry spun sheets. The sheet, possessing a structure of its own, obviates the need for solution processing to create films, which allows it to be used for architectures that demand a freestanding sheet of carbon nanotubes or drawn into a fiber of bundled carbon nanotubes. These freestanding carbon nanotubes were used specifically for the tandem devices and the proposed fiber-based dye solar cells.

Velten, Josef Aaron

70

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

SciTech Connect

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

Zimmerman, T.

1991-08-01

71

Nanostructured materials and their charge transport properties in photoanodes of dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

Since the big progress of dye sensitized solar cells (DSCs) by adopting TiO2 nanoparticles for a photoanode in 1991, DSCs have been intensively studied as an alternative to conventional Si-based solar cells. As a main component of DSCs, a photoanode composed of a nanostructured semiconducting oxide network plays a significant role in determining performances of DSCs in terms of light harvesting efficiency (LHE) and charge collection efficiency related to charge transport and recombination. Nanomaterials with various morphologies, such as particles, rods and tubes have been fabricated and investigated to improve performances of DSCs. Among them, submicrometer-sized aggregates of nanocrystallites have demonstrated to be promising as a photoanode of DSCs for higher power conversion efficiency. Such hierarchical structures make it possible to have both high specific surface area for dye molecule adsorption and internal light scattering within the photoanode, leading to a much enhanced LHE. This work focused on the surface modification and charge transport characterization of such hierarchically structured photoanodes. First, a core-shell configuration was fabricated by atomic layer deposition (ALD) process, which was achieved by depositing ultrathin TiO2 layer on inner surface of ZnO aggregate film in which the TiO2 shell was anticipated to act as a chemical and energy barrier. Although the ALD-TiO2 coating failed to improve chemical stability of the ZnO aggregate against to an acidic dye solution due to the ultrathin thickness (< 1 nm), the ALD-TiO2 shell layer effectively suppressed charge recombination at the interface. As a result of the reduced charge recombination, Voc, and FF of DSCs were increased, leading to 20 % enhancement of power conversion efficiency. Second, effects of annealing temperatures on ALD-TiO2 coated aggregates of ZnO nanocrystallites were investigated in terms of sintering behavior and charge transport. 350 °C as the maximum temperature was typically used to preserve the specific surface area of ZnO aggregates. Nitrogen sorption analyses revealed that the ALD-TiO2 layer improved thermal stability of ZnO aggregates at high temperature, ALD-TiO2 coated ZnO aggregates retained the same specific surface area even annealed at 450 °C. The higher annealing temperature resulted in an improved crystallinity, resulting in the highest charge transfer resistance when annealed at 450 °C. As a result, the DSC with photoanode made of ALD-TiO2 coated ZnO aggregates annealed at 450 °C showed the highest Voc and FF, with a little reduced Jsc and thus, the highest power conversion efficiency. Third, charge transport properties such as electron lifetime, chemical diffusion coefficient and diffusion length of ZnO nanorod aggregates were investigated. Electrochemical impedance spectroscopy (EIS) was used to characterize charge transport properties, and it was found that increased crystal sizes and widened necks with higher annealing temperature reduced charge diffusion resistance (Rd), and increased diffusion length from 50 microm to 140 microm. As a result, the power conversion efficiency increased 25 %. Lastly, TiO2 nanoparticles were added into TiO2 aggregates with different ratios; 10 wt% and 20 wt% nanoparticle. As a result, diffusion resistance was found to be reduced and the corresponding diffusion length was increased by filling the bottlenecks between adjacent aggregates with nanoparticles, while additional reduction of diffusion resistance was not observed when the amount of the added TiO 2 nanoparticles increased from 10 to 20 wt%, indicating that there is a saturation point for charge transport. Even though there was no significant impact of the added nanoparticles on electron lifetime despite of the increase of surface area, admixing TiO2 aggregates with TiO2 nanoparticles improved Jsc and eventually leaded to the enhanced efficiency by 30 % as a result of the improved diffusion length and increased surface area.

Ponsaing, Anita Kristine

72

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

73

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

PubMed

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

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

2014-03-15

74

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

75

Operational Amplifiers  

NSDL National Science Digital Library

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

Kuphaldt, Tony R.

2008-07-14

76

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 s...

Meshcheryakov, Oleg

2014-01-01

77

Single electron charge sensitivity of liquid-gated carbon nanotube transistors.  

PubMed

Random telegraph signals corresponding to activated charge traps were observed with liquid-gated CNT FETs. The high signal-to-noise ratio that we observe demonstrates that single electron charge sensing is possible with CNT FETs in liquids at room temperature. We have characterized the gate-voltage dependence of the random telegraph signals and compared to theoretical predictions. The gate-voltage dependence clearly identifies the sign of the activated trapped charge. PMID:25160798

Sharf, Tal; Wang, Neng-Ping; Kevek, Joshua W; Brown, Morgan A; Wilson, Heather; Heinze, Stefan; Minot, Ethan D

2014-09-10

78

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

79

Examination of the charge-sensitive vibrational modes in bis(ethylenedithio)tetrathiafulvalene.  

PubMed

We reinvestigated the two C=C stretching modes of the five-membered rings of ET (ET = bis(ethylenedithio)tetrathiafulvalene), namely, nu(2) (in-phase mode) and nu(27) (out-of-phase mode). The frequency of the nu(27) mode of ET(+) was corrected to be approximately 1400 cm(-1), which was identified from the polarized infrared reflectance spectra of (ET)(ClO(4)), (ET)(AuBr(2)Cl(2)), and the deuterium- or (13)C-substituted compounds of (ET)(AuBr(2)Cl(2)). It was clarified from DFT calculations that the frequency of the nu(27) mode of the flat ET(0) molecule was significantly different from that of the boat-shaped ET(0) molecule. We obtained the linear relationship between the frequency and the charge on the molecule, rho, for the flat ET molecule, which was shown to be nu(27)(rho) = 1398 + 140(1 - rho) cm(-1). The frequency shift due to oxidation is remarkably larger than that reported in previous studies. The fractional charges of several ET salts in a charge-ordered state can be successfully estimated by applying this relationship. Therefore, the nu(27) mode is an efficient probe to detect rho in the charge-transfer salts of ET. Similarly, a linear relationship for the nu(2) mode was obtained as nu(2)(rho) = 1447 + 120(1 - rho). This relationship was successfully applied to the charge-poor molecule of theta-type ET salts in the charge-ordered state but could not be applied to the charge-rich molecule. This discrepancy was semiquantitatively explained by the hybridization between the nu(2) and nu(3) modes. PMID:16852928

Yamamoto, Takashi; Uruichi, Mikio; Yamamoto, Kaoru; Yakushi, Kyuya; Kawamoto, Atushi; Taniguchi, Hiromi

2005-08-18

80

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

81

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

PubMed

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

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

2014-01-01

82

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

83

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

84

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

85

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

86

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

PubMed

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

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

2012-12-01

87

Comparison of charge accumulation and transport in nanostructured dye-sensitized solar cells with electrolyte or CuSCN as hole conductor  

Microsoft Academic Search

The charge transport properties of the dye-sensitized solar cells consisting of Ru(dcbpyH2)2(NCS)2-sensitized nanostructured TiO2 with either redox electrolyte or CuSCN as hole conductor have been compared. The electron transport time and the electron charge in the TiO2 varies in a similar way with the incident light intensity for both hole conductors: electron transport becomes faster and electron accumulation increases with

Boriss Mahrov; Anders Hagfeldt; Frank Lenzmann; Gerrit Boschloo

2005-01-01

88

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

NASA Astrophysics Data System (ADS)

The electron transfer reaction between the photoinjected electrons in the nanocrystalline TiO2 mesoporous sensitized films and the oxidized electrolyte in dye sensitized solar cells (DSSC) plays a major role on the device efficiency. In this communication we show that, although the presence of molecular aggregates on the free base porphyrin DSSC limits the device photocurrent response under illumination, they form an effective hydrophobic barrier against the oxidized electrolyte impeding fast back-electron transfer kinetics. Therefore, their drawback can be overcome by designing dyes with peripheral moieties that prevent the formation of the aggregates and are able to achieve efficiencies as high as 3.2% under full sun.

Planells, Miquel; Forneli, Amparo; Martínez-Ferrero, Eugenia; Sánchez-Díaz, Antonio; Sarmentero, Maria Angeles; Ballester, Pablo; Palomares, Emilio; O'Regan, Brian C.

2008-04-01

89

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

90

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

PubMed

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

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

2013-01-21

91

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

92

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

2006-01-03

93

Micron resolution of MÖNCH and GOTTHARD, small pitch charge integrating detectors with single photon sensitivity  

NASA Astrophysics Data System (ADS)

MÖNCH, a charge integrating readout ASIC (Application Specific Integrated Circuit) prototype with a pixel pitch of 25 ?m developed at PSI, allows new imaging applications in the field of micron resolution and spectral imaging. The small pixel size of this system facilitates charge sharing between pixels, which then can be exploited to gain additional information about the photon absorption position and photon energy. However, for reconstructing complete images from this information, sufficient hits need to be recorded and therefore acquisition times are potentially long. We present a fast read-out system, that is capable of acquiring enough statistics for an image in a few hours in combination with a position reconstruction algorithm, which has the potential to run in a similar amount of time on a fast computing node. We further present results of experiments with a comparable strip detector (small-pitch GOTTHARD system) showing that with the aid of single photon interpolation algorithms micron resolution is achievable. Additionally, we show that a similar position reconstruction algorithm works in the two dimensional case for MÖNCH.

Cartier, S.; Bergamaschi, A.; Dinapoli, R.; Greiffenberg, D.; Johnson, I.; Jungmann, J. H.; Mezza, D.; Mozzanica, A.; Schmitt, B.; Shi, X.; Stampanoni, M.; Sun, J.; Tinti, G.

2014-05-01

94

Thermally sensitive reversible microgels formed by poly(N-Isopropylacrylamide) charged chains: a Hofmeister effect study.  

PubMed

In this study, we present a new method to obtain anionic and cationic stable colloidal nanogels from PNIPAM charged chains. The stability of the particles formed by inter-chain aggregation stems from the charged chemical groups attached at the sides of PNIPAM polymer chains. The particle formation is fully reversible-that is, it is possible to change from stable polymer solutions to stable colloidal dispersions and vice versa simply by varying temperature. In addition, we also demonstrate that the polymer LCST (lower critical solution temperature), the final particle size and the electrokinetic behavior of the particles formed are highly dependent on the electrolyte nature and salt concentration. These latter results are related to Hofmeister effects. The analysis of these results provides more insights about the origin of this ionic specificity, confirming that the interaction of ions with interfaces is dominated by the chaotropic/kosmotropic character of the ions and the hydrophobic/hydrophilic character of the surface in solution. PMID:24863797

López-León, Teresa; Ortega-Vinuesa, Juan L; Bastos-González, Delfi; Elaissari, Abdelhamid

2014-07-15

95

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

96

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

97

Fluorescent probing of protein bovine serum albumin stability and denaturation using polarity sensitive spectral response of a charge transfer probe.  

PubMed

The polarity sensitive photo-induced intra-molecular charge transfer (ICT) fluorescence probe (E)-3-(4-methylamino-phenyl)-acrylic acid ethyl ester (MAPAEE) has been used to study the model protein Bovine Serum Albumin (BSA) in its native and thermal and urea induced denatured states. The interaction between BSA and the regular surfactant Sodium Dodecyl Sulphate (SDS) as well as the biologically relevant steroid-based amphiphile Sodium Deoxycholate (NaDC) has also been very keenly followed using this ICT probe. The variation of micellar properties of both SDS and NaDC with increasing ionic strengths and in presence of the chaotrope urea has also been well documemted by the same probe. Steady-state spectroscopy, FRET, and fluorescence anisotropy measurements have been used to gain better insight into these processes and the molecule MAPAEE to be a full-bodied fluorescent probe for studying such intricate biological systems, their properties and interactions. PMID:20922468

Ghosh, Shalini; Jana, Sankar; Nath, Debnarayan; Guchhait, Nikhil

2011-01-01

98

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

99

Understanding interfacial charge transfer between metallic PEDOT counter electrodes and a cobalt redox shuttle in dye-sensitized solar cells.  

PubMed

Conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with iron(III) tris-p-toluenesulfonate (PEDOT:Tos) having metallic conductivity was coated onto fluorine-doped tin oxide (FTO) glass and plain glass substrates and used as a counter electrode (CE) in a dye-sensitized solar cell (DSC) with a [Co(bpy)3](3+/2+) complex redox shuttle. DSCs with PEDOT:Tos/glass CE yielded power conversion efficiencies (PCE) of 6.3%, similar to that of DSCs with platinized FTO glass CE (6.1%). The PEDOT:Tos-based counter electrodes had 5 to 10 times lower charge-transfer resistance than the Pt/FTO CE in DSCs, as analyzed by impedance spectroscopy. More detailed studies in symmetrical CE-CE cells showed that the PEDOT:Tos layers are nanoporous. Not all internal area can be used catalytically under solar cell conditions and effective charge-transfer resistance was similar to that of Pt/FTO. PMID:24410094

Park, Byung-wook; Pazoki, Meysam; Aitola, Kerttu; Jeong, Seunghee; Johansson, Erik M J; Hagfeldt, Anders; Boschloo, Gerrit

2014-02-12

100

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

101

Amplified OTDR systems for multipoint corrosion monitoring.  

PubMed

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

102

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.; Coelho, Isnaldo J. S.; Cipriano, Eliel; Martins-Filho, Joaquim F.

2012-01-01

103

Highly sensitive potentiometric strip test for detecting high charge density impurities in heparin.  

PubMed

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

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

2011-05-15

104

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

105

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)

2008-01-01

106

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

107

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

108

Hybrid matrix amplifier  

DOEpatents

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

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

1995-01-03

109

Hybrid matrix amplifier  

DOEpatents

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

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

1995-01-01

110

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

111

Amplified spontaneous emission in Cassegrainian amplifiers  

SciTech Connect

We consider all possible paths for amplified spontaneous emission (ASE) in multipass laser amplifiers using a Cassegrainian telescope geometry. In particular, we study ASE which is reflected back into the medium off the telescope mirrors themselves. These ASE components are unavoidable in this amplifier geometry. We show that there is a component of the ASE which makes approximately double the number of passes through the amplifier as the laser signal makes. We also show that these high order ASE components are also present in amplifiers which are almost Cassegrainian. They cannot be eliminated by changing the ratio of the scraper and hole radii or the separation of the mirrors. It is likely that these ASE components will be more significant in pulsed lasers than cw lasers.

Eimerl, D.

1987-05-01

112

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

113

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

114

The effect of hydrophobic absorbent for reducing charge recombination to improve dye-sensitized solar cell performance  

NASA Astrophysics Data System (ADS)

Normally, it has been widely acceptable that dye sensitized solar cell (DSSC) plays important roles compared to the conventional solar cells such as monocrystalline, polycrystalline, and even amorphous silicon in accordance with its low manufacturing and fabrication cost. However, the DSSC consists of many interfaces between anode and cathode such as semiconductor to dye and dye to electrolyte and electrolyte to platinum catalyst at the cathode. Therefore, the effect of charge recombination at dye-electrolyte interface is a major role to cell efficiency. One of major implementations to alleviate the recombination effect could be efficiently solved by adding hydrophobic co-adsorbent to dye solution. The co-absorbent molecule will be anchored to titanium dioxide semiconductor like dye and can be the barrier to protect the interface of the triiodide, dye and mesoporous titanium dioxide (TiO II). In our works, we investigate on various hydrophobic co-adsorbent such as 1-adamantane acetic acid, cholic acid and chenodeoxy cholic acid. The amounts of the co-absorbent were varied as well as the amount of dye N719. It was found that the cholic and chenodeoxy cholic acid increase photovoltage and photocurrent, especially when the concentration was increased. This may be due to shift of conduction band (CB) to negative direction by the co-absorbent but 1-adamantane-acetic acid could not resist charge recombination. In addition multilayer of titanium dioxide was also studied on the effect of conversion efficiency. The maximum 4 layers of TiO II provided the best cell performance of 8.3 efficiency with the presence of cholic acid.

Sae-Kung, C.; Hatha, E.; Sichanugrist, P.; Pungwiwut, N.; Laosooksathit, S.

2007-09-01

115

Repeated episodes of ozone inhalation amplifies the effects of allergen sensitization and inhalation on airway immune and structural development in Rhesus monkeys  

Microsoft Academic Search

Twenty-four infant rhesus monkeys (30 days old) were exposed to 11 episodes of filtered air (FA), house dust mite allergen aerosol (HDMA), ozone (O3), or HDMA + O3 (5 days each followed by 9 days of FA). Ozone was delivered for 8 h\\/day at 0.5 ppm. Twelve of the monkeys were sensitized to house dust mite allergen (Dermatophagoides farinae) at

Edward S Schelegle; Lisa A Miller; Laurel J Gershwin; Michelle V Fanucchi; Laura S Van Winkle; Joan E Gerriets; William F Walby; Valerie Mitchell; Brian K Tarkington; Viviana J Wong; Gregory L Baker; Lorraine M Pantle; Jesse P Joad; Kent E Pinkerton; Reen Wu; Michael J Evans; Dallas M Hyde; Charles G Plopper

2003-01-01

116

Electron transport and recombination in dye-sensitized mesoporous TiO2 probed by photoinduced charge-conductivity modulation spectroscopy with Monte Carlo modeling.  

PubMed

We present a combined experimental and theoretical investigation into the charge transport and recombination in dye-sensitized mesoporous TiO2. We electronically probe the photoinduced change in conductivity through in-plane devices while simultaneously optically probing signatures of the charge species. Our quasi-continuous wave technique allows us to build data sets of electron mobility and recombination versus charge density over a wide temperature range. We observe that the charge density dependence of mobility in TiO2 is strong at high temperatures and gradually reduces with reducing temperature, to an extent where at temperatures below 260 K the mobility is almost independent of charge density. The mobility first increases and then decreases with reducing temperature at any given charge density. These observed trends are surprising and consistent with the multiple-trapping model for charge transport only if the trap density-of-states (DoS) is allowed to become less deep and narrower as the temperature reduces. Our recombination measurements and simulations over a broad range of charge density and temperature are also consistent with the above-mentioned varying DoS function when the recombination rate constant is allowed to increase with temperature, itself consistent with a thermally activated charge-transfer process. Further to using the Monte Carlo simulations to model the experimental data, we use the simulations to aid our understanding of the limiting factors to charge transport and recombination. According to our model, we find that the charge recombination is mainly governed by the recombination reaction rate constant and the charge density dependence is mainly a result of the bimolecular nature of the recombination process. The implication to future material design is that if the mobility can be enhanced without increasing the charge density in the film, for instance by reducing the average trap depth, then this will not be at the sacrifice of comparably enhanced recombination and it will greatly increase the charge carrier diffusion lengths in dye-sensitized or mesoscopic solar cells. PMID:18767840

Petrozza, Annamaria; Groves, Chris; Snaith, Henry J

2008-10-01

117

Laser amplifier chain  

DOEpatents

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

Hackel, Richard P. (Livermore, CA)

1992-01-01

118

Two-port directional parametric amplifier  

NASA Astrophysics Data System (ADS)

Parametric amplifiers working at the quantum limit are indispensable for fast, accurate measurements of superconducting qubits and other sensitive mesoscopic systems. Conventional microwave parametric amplifiers usually operate as one-port reflection devices and rely on non-reciprocal components like circulators. Besides affecting the magnetic environment near delicate superconducting devices, circulators are problematic for on-chip integration owing to their relatively bulky size. We will present the results of a theoretical analysis of a minimal-noise directional amplifier based on parametric Josephson devices, which would avoid the need for circulators in quantum-limited measurements. The link between the non-reciprocal operation of this amplifier and the dynamics of the microwave dc SQUID amplifier will be discussed.

Kamal, Archana; Devoret, Michel; Clarke, John

2010-03-01

119

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

120

Influence of polar medium on the reorganization energy of charge transfer between dyes in a dye sensitized film.  

PubMed

We study the kinetics of the lateral hole transfer occurring between dye molecules anchored at the surface of the metal oxide in Dye Sensitized Solar Cells (DSSC). We use Marcus' charge transfer rate equation for which we need the electronic coupling between two molecules (J) and the reorganization energy (?tot). In DSSC the medium surrounding the dyes is highly polar. This means that the contribution of the solvent to the reorganization energy cannot be neglected. Here we elaborate a method to calculate, from first principles, the total (i.e., inner- and outer-sphere) reorganization energy of hole exchange between ruthenium dyes. The influence of the solvent and of the ions in the solvent is incorporated. The inner-sphere reorganization energy depends on the nature of the dye, 0.1 eV for ruthenium dyes with CN ligands, 0.2 eV for ruthenium dyes with NCS ligands. In acetonitrile, the solvent reorganization energy contributes for at least 80% of the total giving a total reorganization energy of around 0.86 eV for ruthenium dyes with CN ligands and 0.95 eV for ruthenium dyes with NCS ligands. We use these results to estimate the rate of hole transfer within Marcus theory. We suggest that low diffusion coefficients observed experimentally may arise from the high polarity of the medium rather than by the chemical structure of the dye. PMID:23439984

Vaissier, Valérie; Barnes, Piers; Kirkpatrick, James; Nelson, Jenny

2013-04-01

121

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

122

Chlorophyll-a derivatives with various hydrocarbon ester groups for efficient dye-sensitized solar cells: static and ultrafast evaluations on electron injection and charge collection processes.  

PubMed

Five chlorophyll-a derivatives, chlorins-1-5 possessing C3(2)-carboxy and O17(4)-esterified hydrocarbon groups including methyl, hexyl, dodecyl, 2-butyloctyl, and cholesteryl were synthesized. Their performance as sensitizers in dye-sensitized solar cells (DSSCs) was compared. These sensitizers have similar surface coverage on the unit surface of TiO(2) film and their absorption spectra on transparent TiO(2) films were identical. On the basis of DFT and TD-DFT calculations of these sensitizers in ethanol, a major difference between them was the geometry of the hydrocarbon ester group, to affect their electron injection and charge recombination with the TiO(2) electrode rather than the energy level of their molecular orbitals. DSSC based on chlorin-3 with a dodecyl ester group gave a solar energy-to-electricity conversion efficiency of 8%, which was the highest among all the chlorophyllous sensitizers. The large photocurrent in the chlorin-3 sensitized solar cell can be explained by the least impedance in the electrolyte-dye-TiO(2) interface in electrical impedance spectroscopy measurements. Subpicosecond time-resolved absorption spectroscopic studies have also been carried out to evaluate the electron injection and charge recombination dynamics in the dye-TiO(2) interface. For the electron injection and charge recombination processes, a charge separated state of the dye-TiO(2) complex has been found to be free from the type and concentration of dye sensitizer, reflecting the same type of electron transfer process for all the five chlorin sensitizers. A new quenching pathway of the dye excitation, which is probably from the exciton annihilation, in addition of the charge recombination has been observed for chlorin-1 and chlorin-5, but not for chlorin-3. The higher open-circuit photocurrent observed in the present dyes with larger ester groups can be attributed to the reduced leaking of charges in the TiO(2)-electrolyte interface, which was supported by the longer electron lifetimes. PMID:20380394

Wang, Xiao-Feng; Tamiaki, Hitoshi; Wang, Li; Tamai, Naoto; Kitao, Osamu; Zhou, Haoshen; Sasaki, Shin-ichi

2010-05-01

123

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

PubMed

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

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

2015-01-15

124

Design criteria for electronics for resistive charge division in thermal neutron detection  

Microsoft Academic Search

An amplifier has been designed for optimal use of position-sensitive thermal neutron detectors based upon the principle of resistive charge division. The important points in this optimization are: high counting rates and good spatial resolution (low noise). In this paper, we present a short theoretical analysis of the problem that led us to our design. We make an analysis of

Patrick Van Esch; Thomas Gahl; Bruno Guérard

2004-01-01

125

Wireless Josephson Amplifier  

E-print Network

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

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

2014-04-19

126

Wireless Josephson amplifier  

NASA Astrophysics Data System (ADS)

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.

2014-06-01

127

Integrated CMOS RF amplifier  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

128

Dye laser amplifier  

DOEpatents

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

Moses, Edward I. (Livermore, CA)

1992-01-01

129

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

130

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

131

Ultrafast polarisation spectroscopy of photoinduced charges in a conjugated polymer  

SciTech Connect

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

Bakulin, A A; Loosdrecht, P van; Pshenichnikov, M S [Zernike Institute for Advanced Materials, University of Groningen, Groningen (Netherlands); Parashchuk, D Yu [M. V. Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation)

2009-07-31

132

Fully relayed regenerative amplifier  

DOEpatents

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

Glass, Alexander J. (Berkeley, CA)

1981-01-01

133

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

134

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

PubMed

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

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

2013-12-30

135

Suppression of the effect of charge cloud in an ion mobility increment spectrometer to improve its sensitivity  

NASA Astrophysics Data System (ADS)

The formation of a charge cloud due to ions passing through a set of electrodes that constitute an atmospheric-pressure ion mobility increment spectrometer is considered. Since this cloud disturbs the passage of ions separated in the spectrometer, it is suggested that the formation of the cloud be suppressed by shifting the central electrode or applying a voltage to the output electrode. Such a trick removes an ion trap responsible for the charge cloud. It is shown that the transparency of the instrument can be increased severalfold in this case.

Pervukhin, V. V.; Sheven, D. G.

2008-01-01

136

MODEL SR510 LOCK-IN AMPLIFIER  

E-print Network

33 Measurement Example 33 Understanding the Specifications 34 Shielding and Ground Loops 34 Dynamic Diagram Block Diagram 37 Signal Channel 38 Reference Channel 38 Phase-Sensitive Detector 38 DC Amplifier Parts List, Front Panel 94 Schematic Diagrams 99 #12;1 Safety and Preparation for Use ***CAUTION

Gellman, Andrew J.

137

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

138

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

139

Increased charge transfer of PVDF-HFP based electrolyte by addition of graphite nanofiber and its application in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

The PEO and PVDF-HFP mixtures were used as polymer electrolytes in solid-state dye-sensitized solar cells (DSSCs). Correlation between the ionic conductivity and cell performance by varying the composition of polymer electrolytes was investigated to elucidate the importance of the ionic conductivity in determining the charge transfer and energy conversion efficiency of solid-state DSSCs. In this work, for increasing the ionic conductivity and charge transfer, GNF was added to the polymer electrolyte. The ionic conductivity of polymer electrolyte containing GNF (0.005 g) is 8.67 × 10-4 S cm-1 and pristine polymer electrolyte is 3.81 × 10-4 S cm-1. The charge transfer of GNF (0.005 g) added DSSCs is faster than the other samples, the electron transport time is 1.53 ms and electron life time is 27.20 ms. The increase of current density with the polymer electrolyte containing GNF (0.005 g) can be possibly attributed to the direct contact between dye/TiO2 and I/I3- that will improve the charge transportation. The highest energy conversion efficiency of 4.60% is obtained for polymer electrolyte containing GNF (0.005 g).

Zhao, Xing Guan; Jin, En Mei; Gu, Hal-Bon

2013-12-01

140

An interfacial and bulk charge transport model for dye-sensitized solar cells based on photoanodes consisting of core-shell nanowire arrays.  

PubMed

Dye-sensitized solar cells (DSSCs) based on ordered photoanode morphologies, such as nanotubes and nanowires, are widely gaining attention because these geometries are believed to enhance interfacial charge transfer and bulk charge transport. Unfortunately, experimental results have yet to show substantial improvement to conversion efficiency over nanoparticle-based DSSCs. A model is developed to characterize the performance of an idealized photoanode based on an ordered array of transparent conductive nanowires coated with an anatase titania shell. The role of the interfacial electric field in nanowire-based DSSCs is explored computationally by turning electron migration ON or OFF. The results show that back-reaction rates are most strongly influenced by the electric field. These electron loss mechanisms can be reduced by several orders of magnitude, leading to improvements in short-circuit current, open-circuit voltage, and fill factor. PMID:21899330

Hill, Justin J; Banks, Nick; Haller, Kelly; Orazem, Mark E; Ziegler, Kirk J

2011-11-23

141

Laser amplifier and method  

DOEpatents

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

Backus, Sterling (Ann Arbor, MI); Kapteyn, Henry C. (Ann Arbor, MI); Murnane, Margaret M. (Ann Arbor, MI)

1997-01-01

142

High input impedance amplifier  

NASA Technical Reports Server (NTRS)

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

Kleinberg, Leonard L.

1995-01-01

143

Spatial Light Amplifier Modulators  

NASA Technical Reports Server (NTRS)

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

Eng, Sverre T.; Olsson, N. Anders

1992-01-01

144

Dispersive Readout of a Superconducting Qubit Using a SLUG Amplifier  

NASA Astrophysics Data System (ADS)

Developing a fast, high-fidelity readout of superconducting quantum bits (qubits) makes significant demands of the cryogenic amplification chain, where the first stage amplifier must have sufficient sensitivity to resolve the state of the qubit and enough gain to overcome the noise of subsequent stages of amplification. Additionally, the architecture of a scalable quantum computer requires an amplifier with a large enough bandwidth and dynamic range to simultaneously measure multiple qubits without sacrificing performance. In this thesis, we describe a novel low-noise phase-insensitive linear amplifier at microwave frequencies based on the Superconducting Low-Inductance Undulatory Galvanometer (SLUG), an amplifier capable of meeting the demands of the superconducting qubit community. We discuss the numerical optimization of the SLUG amplifier and calculate the expected amplifier gain and noise temperature. We walk through the amplifier design and fabrication process before discussing how to fully characterize the fabricated device. We report on amplifiers with measured gain of 10 to 15 dB, bandwidths from 50 to 100 MHz, and added system noise below 2 quanta. Next, we describe the qubit- cavity system and the limits of a dispersive quantum measurement using circuit quantum electrodynamics. Finally, we report on experiments where a SLUG amplifier is used to measure the state of a superconducting qubit, demonstrating improved measurement signal-to-noise ratios of 10 dB and a dynamic range that is an order of magnitude better than any available amplifier currently being developed.

Hover, David James

145

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

146

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

PubMed

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

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

2014-03-21

147

Charged Leptons  

E-print Network

This is the report of the Intensity Frontier Charged Lepton Working Group of the 2013 Community Summer Study "Snowmass on the Mississippi", summarizing the current status and future experimental opportunities in muon and tau lepton studies and their sensitivity to new physics. These include searches for charged lepton flavor violation, measurements of magnetic and electric dipole moments, and precision measurements of the decay spectrum and parity-violating asymmetries.

J. Albrecht; M. Artuso; K. Babu; R. H. Bernstein; T. Blum; D. N. Brown; B. C. K. Casey; C. -h. Cheng; V. Cirigliano; A. Cohen; A. Deshpande; E. C. Dukes; B. Echenard; A. Gaponenko; D. Glenzinski; M. Gonzalez-Alonso; F. Grancagnolo; Y. Grossman; R. C. Group; R. Harnik; D. G. Hitlin; B. Kiburg; K. Knoepfe; K. Kumar; G. Lim; Z. -T. Lu; D. McKeen; J. P. Miller; M. Ramsey-Musolf; R. Ray; B. L. Roberts; M. Rominsky; Y. Semertzidis; D. Stoeckinger; R. Talman; R. Van De Water; P. Winter

2013-11-21

148

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

149

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

150

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

151

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

152

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

PubMed Central

The effect of cholesterol on the bilayer partitioning of the peptide GALA (WEAALAEALAEALAEHLAEALAEALEALAA) and its assembly into a pore in large unilamellar vesicles composed of neutral and negatively charged phospholipids has been determined. GALA undergoes a conformational change from a random coil to an amphipathic alpha-helix when the pH is reduced from 7.0 to 5.0, inducing at low pH leakage of contents from vesicles. Leakage from neutral or negatively charged vesicles at pH 5.0 was similar and could be adequately explained by the mathematical model (Parente, R. A., S. Nir, and F. C. Szoka, Jr., 1990. Mechanism of leakage of phospholipid vesicle contents induced by the peptide GALA. Biochemistry. 29:8720-8728) which assumed that GALA becomes incorporated into the vesicle bilayer and irreversibly aggregates to form a pore consisting of 10 +/- 2 peptides. Increasing cholesterol content in the membranes resulted in a reduced efficiency of the peptide to induce leakage. Part of the cholesterol effect was due to reduced binding of the peptide to cholesterol-containing membranes. An additional effect of cholesterol was to increase reversibility of surface aggregation of the peptide in the membrane. Results could be explained and predicted with a model that retains the same pore size, i.e., 10 +/- 2 peptides, but includes reversible aggregation of the monomers to form the pore. Resonance energy transfer experiments using fluorescently labeled peptides confirmed that the degree of reversibility of surface aggregation of GALA was significantly larger in cholesterol-containing liposomes, thus reducing the efficiency of pore formation. PMID:8968598

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

1996-01-01

153

Numerical and analytical modeling of polarization-dependent gain in erbium-doped fiber amplifiers  

NASA Astrophysics Data System (ADS)

We present a rate-equation model that accounts for polarization hole burning in erbium-doped fiber amplifiers. This model yields analytical expressions for the polarization sensitivity of the amplifier for arbitrary signal polarization states. We investigate the influence of the birefringence properties of the fiber and calculate the average polarization properties of an amplifier chain. Copyright (c) 1995 Optical Society of America

Leners, R.; Georges, T.

1995-10-01

154

A Linear, Wideband, Low-Noise Amplifier Stage for Use in Nuclear Pulse Amplifiers  

Microsoft Academic Search

The design evolution of a wideband voltage-sensitive amplifier stage is presented. For the basic stage, including a new driver configuration and overload control circuit, three basic input sections are considered; the first section consists of differentially connected bipolar transistors for use with low generator impedances, the second consists of medium-transconductance FETs to allow larger coupling time constants, and the third

J. K. Millard; T. V. Blalock

1970-01-01

155

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

156

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

157

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

158

Saturated Operational Amplifier  

NSDL National Science Digital Library

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

2009-11-27

159

Improved-Bandwidth Transimpedance Amplifier  

NASA Technical Reports Server (NTRS)

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

Chapsky, Jacob

2009-01-01

160

Chirped pulse Raman amplifier  

NASA Astrophysics Data System (ADS)

All modern terawatt- and petawatt-class laser systems are based on the principle of chirped-pulse amplification (CPA). In this work, a compact subsystem that shifts a micro-joule portion of the chirped pulse energy to a new wavelength outside its original bandwidth, then amplifies it to millijoule energy without adding pump lasers, and without compromising the output of the fundamental CPA system in any significant way, has been developed and integrated into a standard terawatt-class CPA system. In this chirped pulse Raman amplifier sub-system, a 30 mJ portion of a chirped 800 nm fundamental pulse within the CPA system was split into two unequal portions, each of which impinged on a Raman-active barium nitrate, or Ba(NO3)2, crystal of length 5 cm. The weaker portion created a weak (15 J) first Stokes pulse (873 nm) by Stimulated Raman Scattering (SRS) in the first crystal, which then seeded a non-collinear four-wave-mixing process driven by the stronger portion of the split-off CPA pulse in the second crystal. The latter process amplified the first Stokes seed pulse to several millijoules with excellent beam quality. A study of Raman gain as a function of time delay between pump and Stokes pulse in the second crystal revealed a sharply peaked narrow interval (˜3 ps FWHM) of high gain and a wider interval (˜50 ps) of low gain. The amplified, chirped first Stokes pulse was successfully compressed to 100 fs duration using a grating pair of different line density than in the main CPA system, based on a comprehensive dispersion analysis of the optical path of the first Stokes pulse. The possibility of generating higher-order Stokes and anti-Stokes sidebands of the CPA pulse is also demonstrated. Further amplification of the sideband pulse by conventional methods, using an additional pump laser, appears straightforward. The chirped pulse Raman amplifier provides temporally synchronized fundamental and Raman sideband pulses for performing two-color, high-intensity laser experiments, some of which are briefly discussed. It can be integrated into any standard CPA system, and provides significant new versatility for high-intensity laser sources.

Grigsby, Franklin Bhogaraju

161

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

162

Fiber parametric amplifiers for wavelength band conversion  

Microsoft Academic Search

By using a loop configuration formed by a polarization beam splitter, we experimentally demonstrate that the existing wavelength-division multiplexing (WDM) sources in C-band can be wavelength converted to the S-band with low polarization sensitivity and low crosstalk. Using a fiber parametric amplifier as a band converter, we achieve experimentally 4.7-dB conversion efficiency over 30-nm conversion bandwidth in 315 m of

Mohammed N. Islam; O. Boyraz

2002-01-01

163

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

PubMed

A novel, low-cost, pixel-based detector array (described elsewhere Sinha and Wadsworth (76(2), 1) is examined using different charged particles, from electrons to hyperthermal (<100 eV) large biomolecular positive and negative ions, including keV small atomic and molecular ions. With this in mind, it is used in instrumentation design (beam profiling), mass spectrometry, and electron spectroscopy. The array detector is a modified light-sensitive charge-coupled device (CCD) that was engineered for direct charged-particle detection by replacing the semiconductor part of the CCD pixel with a conductor Sinha and Wadsworth (76(2), 1). The device is referred to as the IonCCD. For the first time, we show the direct detection of 250-eV electrons, providing linearity response of the IonCCD to the electron beam current. We demonstrate that the IonCCD detection efficiency is virtually independent from the particle energy (250 eV, 1250 eV), impact angle (45(o), 90(o)) and flux. By combining the IonCCD with a double-focusing sector field mass spectrometer (MS) of Mattauch-Herzog geometry (MH-MS), we demonstrate fast data acquisition. Detection of hyperthermal biomolecular ions produced using an electrospray ionization source (ESI) is also presented. In addition, the IonCCD was used as a beam profiler to characterize the beam shape and intensity of 15 eV protonated and deprotonated biomolecular ions at the exit of an rf-only collisional quadrupole. This demonstrates an ion-beam profiling application for instrument design. Finally, we present simultaneous detection of 140 eV doubly protonated biomolecular ions when the IonCCD is combined with the MH-MS. This demonstrates the possibility of simultaneous separation and micro-array deposition of biological material using a miniature MH-MS. PMID:21472600

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

2011-04-01

164

Molecular engineering of simple phenothiazine-based dyes to modulate dye aggregation, charge recombination, and dye regeneration in highly efficient dye-sensitized solar cells.  

PubMed

A series of simple phenothiazine-based dyes, namely, TP, EP, TTP, ETP, and EEP have been developed, in which the thiophene (T), ethylenedioxythiophene (E), their dimers, and mixtures are present to modulate dye aggregation, charge recombination, and dye regeneration for highly efficient dye-sensitized solar cell (DSSC) applications. Devices sensitized by the dyes TP and TTP display high power conversion efficiencies (PCEs) of 8.07 (Jsc = 15.2?mA?cm(-2), Voc =0.783?V, fill factor (FF) = 0.679) and 7.87?% (Jsc = 16.1?mA?cm(-2), Voc = 0.717?V, FF = 0.681), respectively; these were measured under simulated AM 1.5 sunlight in conjunction with the I(-)/I3(-) redox couple. By replacing the T group with the E unit, EP-based DSSCs had a slightly lower PCE of 7.98?% with a higher short-circuit photocurrent (Jsc) of 16.7?mA?cm(-2). The dye ETP, with a mixture of E and T, had an even lower PCE of 5.62?%. Specifically, the cell based on the dye EEP, with a dimer of E, had inferior Jsc and Voc values and corresponded to the lowest PCE of 2.24?%. The results indicate that the photovoltaic performance can be finely modulated through structural engineering of the dyes. The selection of T analogues as donors can not only modulate light absorption and energy levels, but also have an impact on dye aggregation and interfacial charge recombination of electrons at the interface of titania, electrolytes, and/or oxidized dye molecules; this was demonstrated through DFT calculations, electrochemical impedance analysis, and transient photovoltage studies. PMID:24715494

Hua, Yong; Chang, Shuai; He, Jian; Zhang, Caishun; Zhao, Jianzhang; Chen, Tao; Wong, Wai-Yeung; Wong, Wai-Kwok; Zhu, Xunjin

2014-05-19

165

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

PubMed

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

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

2014-03-11

166

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

PubMed Central

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

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

2011-01-01

167

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

PubMed

Zinc oxide (ZnO) nanorods decorated with gold (Au) nanoparticles have been synthesized and used to fabricate dye-sensitized solar cells (DSSC). The picosecond-resolved, time-correlated single-photon-count (TCSPC) spectroscopy technique was used to explore the charge-transfer mechanism in the ZnO/Au-nanocomposite DSSC. Due to the formation of the Schottky barrier at the ZnO/Au interface and the higher optical absorptions of the ZnO/Au photoelectrodes arising from the surface plasmon absorption of the Au nanoparticles, enhanced power-conversion efficiency (PCE) of 6.49% for small-area (0.1 cm(2)) ZnO/Au-nanocomposite DSSC was achieved compared to the 5.34% efficiency of the bare ZnO nanorod DSSC. The TCSPC studies revealed similar dynamics for the charge transfer from dye molecules to ZnO both in the presence and absence of Au nanoparticles. A slower fluorescence decay associated with the electron recombination process, observed in the presence of Au nanoparticles, confirmed the blocking of the electron transfer from ZnO back to the dye or electrolyte by the Schottky barrier formed at the ZnO/Au interface. For large area DSSC (1 cm(2)), ~130% enhancement in PCE (from 0.50% to 1.16%) was achieved after incorporation of the Au nanoparticles into the ZnO nanorods. PMID:22043457

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

2011-01-01

168

Funnel-structured TiO2 electrode for improved charge extraction in dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

We here show that the current density and efficiency of dye-sensitized solar cell (DSSC) can be much enhanced by generating more bulky-structured funnels inside the typical TiO2 electrode. This approach is fundamentally based on the pulsed laser-induced desorption and melting of TiO2 nanoparticles. Three-beam interference was utilized to fabricate the periodic electrode structure. While the dye coverage was little influenced by this process because a small volume fraction of the electrode was converted into the bulky structure, the photoexcited electrons could be more effectively extracted owing to the prolonged diffusion length. As a result, the photocurrent density and efficiency of DSSCs were much improved. The enhancement of both factors was reliably ascertained by the multiple-cell characterization. The funnel cells exhibited an average short-circuit current density of 19.77 mA/cm2 and an efficiency of 9.44%, while 17.30 mA/cm2 and 8.27% were obtained from the reference cells.

Jin, Minhea; Lee, Myeongkyu

2013-10-01

169

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

170

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

171

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

172

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

173

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

PubMed

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

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

2013-01-23

174

The cross-coupled amplifier  

E-print Network

THE CROSS COUPLED AMPLIFIER A Thesis By George Clyde Robinson January 1951 THE CROSS COUPLED AMPLIFIER A Thesis GEORGE CLYDE ROBINSON JANUARY 1951 Approved as to style and content by C airma of Committee THE CROSS-COUPLED AMPLIFIER A... Thesis Submitted to the Faculty of the Agricultural and Mechanical College of Texas in Partial Fulfilment of the Requirements for the Degree of Master of Science Ma]or Sub]ect: Electrical Engineering By George Clyde Robinson January X951 TABLE...

Robinson, George Clyde

2012-06-07

175

90% write power saving SRAM using sense-amplifying memory cell  

Microsoft Academic Search

Summary form only given. A low power write scheme is proposed for an SRAM using seven-transistor sense-amplifying memory cells, which can save 90% of the power in write cycles when 4M SRAM is assumed. By reducing the bit line swing to 1\\/6 VDD and amplifying the voltage swing by a sense-amplifier structure in a memory cell, charging and discharging component

S. Hattori; T. Sakurai

2002-01-01

176

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

177

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

PubMed

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

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

2012-11-14

178

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

179

TiO2 nanorods: a facile size- and shape-tunable synthesis and effective improvement of charge collection kinetics for dye-sensitized solar cells.  

PubMed

In this paper, we present a novel, high-yield, and cost-effective hydrothermal method for the preparation of single crystal-like anatase TiO2 nanorods (NRs) with specific {101} exposed crystal planes and preferred [001] growth direction, which is governed by the "oriented attachment" mechanism. The successful synthesis of TiO2 NRs and fine tuning on their size and shape could be easily accomplished by adjusting the solvent compositions. The salient feature of these NRs, in lieu of traditional nanoparticles as building blocks of photoanodes in dye-sensitized solar cell (DSSC) system, rests with their significantly reduced grain boundaries. The electron diffusion and recombination kinetics have been critically compared for the first time with respect to the size and shape of the novel building blocks. A high efficiency of 8.87% has finally been achieved for DSSC based on long-thin NRs rather than short-thin or long-thick NRs, which possesses balanced optimizations on charge collection and light-harvesting properties. PMID:24833257

Zhang, Wenjun; Xie, Yan; Xiong, Dehua; Zeng, Xianwei; Li, Zhihong; Wang, Mingkui; Cheng, Yi-Bing; Chen, Wei; Yan, Keyou; Yang, Shihe

2014-06-25

180

Hybrid thin-film amplifier  

NASA Technical Reports Server (NTRS)

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

Cleveland, G.

1977-01-01

181

Suicide Risk: Amplifiers and Attenuators.  

ERIC Educational Resources Information Center

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

Plutchik, Robert; Van Praag, Herman M.

1994-01-01

182

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

183

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

184

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

185

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

186

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

187

Planar MESFET transmission wave amplifier  

Microsoft Academic Search

The authors present a quasioptical power combining transmission amplifier for increasing the power level available from solid-state circuits. Receiving and transmitting arrays of patch antennas, input\\/output isolation, MESFETs, bias and matching circuitry are contained on a single substrate, making monolithic millimeter-wave integration possible. The flexibility of selecting input polarization with respect to the output while maintaining amplifier stability is demonstrated.

T. Mader; J. Schoenberg; L. Harmon; Z. B. Popovic

1993-01-01

188

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.

189

Novel SBS suppression scheme for high-power fiber amplifiers  

Microsoft Academic Search

A new scheme for suppression of Stimulated Brillouin Scattering (SBS) in high power fiber amplifiers is proposed where the fiber core diameter varies along the fiber length. The fiber has an ultra-large core diameter at most locations to suppress SBS, while at certain locations the core is relatively small to reduce bending sensitivity. A numerical model based on SBS rate

Anping Liu

2006-01-01

190

Amplified spontaneous emission (ASE) in laser oscillators and amplifiers  

SciTech Connect

Dye-laser oscillators and amplifiers are studied theoretically with inclusion of amplified spontaneous emission (ASE). Assuming pencil-like geometry in both cases, laser signal intensity and ASE intensity are described with appropriate photon transport equations. In particular, there exist different boundary conditions for both fluxes in the laser cavity case due to the different feedback behavior of an optical resonator for laser modes and ASE modes. The interaction of laser output and ASE intensity is discussed in detail, including laser output optimization with and without ASE effects. For single and double pass amplifiers, closed-form solutions for gain saturation due to input signal and ASE flux are also given. More complicated gain functions, such as inclusion of reabsorption in dye lasers, are also treated in some detail.

Haag, G.; Marowsky, G.; Munz, M.

1983-06-01

191

A fully integrated CMOS chopper amplifier  

Microsoft Academic Search

A CMOS chopper amplifier that achieves reduced input offset voltage and fast overload recovery time while maintaining bandwidths comparable to conventional operational amplifiers and requiring no external components is presented. The chopper amplifier consists of two folded cascode operational transconductance amplifiers (OTA) connected in a switched feed-forward configuration, and a third OTA that is used to realize a large capacitive

Doug Garrity; Jenkuan Young; Don Thelen

1991-01-01

192

A continuously pumped iodine laser amplifier  

Microsoft Academic Search

The amplification characteristics were studied for a continuously pumped iodine laser amplifier using n-C3F7I as the amplifying medium. A small-signal amplification of 5 was obtained from a 15 cm long amplifier pumped with 1000 AM0 solar radiation by passing the oscillator output through the amplifier three times.

In Heon Hwang; Kwang S. Han

1991-01-01

193

Limit circuit prevents overdriving of operational amplifier  

NASA Technical Reports Server (NTRS)

Cutoff-type high gain amplifier coupled by a diode prevents overdriving of operational amplifier. An amplified feedback signal offsets the excess input signal that tends to cause the amplifier to exceed its preset limit. The output is, therfore, held to the set clamp level.

Openshaw, F. L.

1967-01-01

194

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

195

500-Watt, 10-GHz Solid State Amplifier  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

196

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

197

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

198

Temporal mode structure of a regenerative amplifier with intracavity etalons  

SciTech Connect

The effects of intracavity etalons on the temporal-mode structure of a regenerative amplifier are studied both theoretically and experimentally. The analysis predicts the temporal profile of the regenerative amplifier output pulse given the temporal profile of the input pulse, the laser-cavity parameters, the etalon parameters, and the number of round trips that the injected pulse makes in the laser cavity. Several experiments were performed. The output pulse width of a regenerative amplifier with a single etalon was measured as we varied the thickness of the etalon and the number of round trips that the injected pulse makes in the laser cavity. With two etalons an injected 70-ps pulse width was stretched to 7 ns with no temporal modulation. The thermal sensitivity of an intracavity etalon was analyzed and measured. All experimental results agree well with theory.

Skeldon, M.D.; Bui, S.T. (Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States))

1993-04-01

199

Bend distortion in large-mode-area amplifier fiber design  

NASA Astrophysics Data System (ADS)

As fibers with ever increasing mode area are used to enable high power fiber amplifiers and lasers, it important to use realistic models of bending in fiber design. The standard approach is to consider only the bend-induced losses and mode-coupling when designing an amplifier, even though changes in mode shape are well known in principle. But even coiling a fiber to fit into a reasonable package size produces large bend-induced distortion for fibers with large mode area. Here, several recent results are reviewed. Distortion significantly impacts amplifier performance by reducing the area, and can further degrade the interaction of light with the gain. Scaling rules for the distortion are derived from an intuitive sensitivity model. Bend distortion considerations lead to new strategies for large mode area fiber design, and cast existing strategies in a new light.

Fini, John M.

2007-11-01

200

The PreAmplifier ShAper for the ALICE TPC detector  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

201

Erbium-doped fiber amplifiers  

Microsoft Academic Search

Erbium-doped fiber amplifiers (EDFAs) operate in the 1.5 micrometers wavelength telecommunications window and have achieved high gain, high output power, and near ideal noise performance. The feasibility of using semiconductor laser diodes to pump EDFAs insures that EDFAs are practical devices that will have great impact on optical communications as power boosters, optical repeaters, and optical preamplifiers.

John L. Zyskind

1992-01-01

202

Cryogenic MMIC Low Noise Amplifiers  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

203

The School as an Amplifier.  

ERIC Educational Resources Information Center

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

Vincent, William S.

1966-01-01

204

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

205

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

206

Does surface roughness amplify wetting?  

PubMed

Any solid surface is intrinsically rough on the microscopic scale. In this paper, we study the effect of this roughness on the wetting properties of hydrophilic substrates. Macroscopic arguments, such as those leading to the well-known Wenzel's law, predict that surface roughness should amplify the wetting properties of such adsorbents. We use a fundamental measure density functional theory to demonstrate the opposite effect from roughness for microscopically corrugated surfaces, i.e., wetting is hindered. Based on three independent analyses we show that microscopic surface corrugation increases the wetting temperature or even makes the surface hydrophobic. Since for macroscopically corrugated surfaces the solid texture does indeed amplify wetting there must exist a crossover between two length-scale regimes that are distinguished by opposite response on surface roughening. This demonstrates how deceptive can be efforts to extend the thermodynamical laws beyond their macroscopic territory. PMID:25399155

Malijevský, Alexandr

2014-11-14

207

338-GHz Semiconductor Amplifier Module  

NASA Technical Reports Server (NTRS)

Research findings were reported from an investigation of new gallium nitride (GaN) monolithic millimeter-wave integrated circuit (MMIC) power amplifiers (PAs) targeting the highest output power and the highest efficiency for class-A operation in W-band (75-110 GHz). W-band PAs are a major component of many frequency multiplied submillimeter-wave LO signal sources. For spectrometer arrays, substantial W-band power is required due to the passive lossy frequency multipliers.

Samoska, Lorene A.; Gaier, Todd C.; Soria, Mary M.; Fung, King Man; Rasisic, Vesna; Deal, William; Leong, Kevin; Mei, Xiao Bing; Yoshida, Wayne; Liu, Po-Hsin; Uyeda, Jansen; Lai, Richard

2010-01-01

208

Direct solar-pumped iodine laser amplifier  

Microsoft Academic Search

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

K. S. Han

1985-01-01

209

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

210

Two stage double layer microstrip spatial amplifiers  

Microsoft Academic Search

Several two stage spatial amplifiers are presented. The amplifiers were constructed on double layer back to back microstrip circuits with a shared ground plane. The ground plane provides an effective isolation between the receiving antenna array and the transmitting antenna array. Furthermore, it serves as a heat sink in high-power amplifier design. The coupling between the two stages is accomplished

Toni Ivanov; Arnir Mortazawi

1995-01-01

211

Solid state, S-band, power amplifier  

NASA Technical Reports Server (NTRS)

The final design and specifications for a solid state, S-band, power amplifier is reported. Modifications from a previously proposed design were incorporated to improve efficiency and meet input overdrive and noise floor requirements. Reports on the system design, driver amplifier, power amplifier, and voltage and current limiter are included along with a discussion of the testing program.

Digrindakis, M.

1973-01-01

212

Modeling erbium-doped fiber amplifiers  

Microsoft Academic Search

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

C. Randy Giles; Emmanuel Desurvire

1991-01-01

213

AC instrumentation amplifier for bioimpedance measurements  

Microsoft Academic Search

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

R. Pallas-Areny; J. G. Webster

1993-01-01

214

Design of hysteresis circuits using differential amplifiers  

NASA Technical Reports Server (NTRS)

Design equations for hysteresis circuit are based on the following assumptions: amplifier input impedance is larger than source impedance; amplifier output impedance is less than load impedance; and amplifier switches state when differential input voltage is approximately zero. Circuits are designed to any given specifications.

Cooke, W. A.

1971-01-01

215

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

216

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

217

Monitoring photoacid generation in chemically amplified resist systems  

NASA Astrophysics Data System (ADS)

A new, simple, highly sensitive, and reliable technique has been developed for measuring acid concentration in solutions and in thin polymer films. This technique is applicable to the study of photoacid generation in chemically amplified resist systems. It employs fluorescent, acid sensitive compounds such as N-(9-acrydinyl)acetamide which undergo large changes in fluorescence as a function of degree of protonation. We have used this technique to quantify the amount of acid generated as a function of 193 nm exposure dose in alicyclic polymer matrices containing photoacid generators such as triphenylsulfonium hexafluoroantimonate. We are continuing to explore the general utility of this new analytical technique which allows the study of diffusional processes and the determination of quantum efficiencies in thin polymer films of the kind used in deep-UV (KrF at 248 nm, ArF at 193 nm) lithography. Such data are of importance in the modeling of chemically amplified resist systems.

Okoroanyanwu, Uzodinma; Byers, Jeff D.; Cao, Ti; Webber, Stephen E.; Willson, C. Grant

1998-06-01

218

Design of a Casimir-driven parametric amplifier  

NASA Astrophysics Data System (ADS)

In this paper, we discuss a design for a MEMS parametric amplifier modulated by the Casimir force. We present the theory for such a device and show that it allows for the implementation of a very sensitive voltage measuring technique, where the amplitude of a high quality factor resonator includes a tenth power dependency on an applied DC voltage. This approach opens up a new and powerful measuring modality, applicable to other measurement types.

Imboden, M.; Morrison, J.; Campbell, D. K.; Bishop, D. J.

2014-10-01

219

NIF/LMJ prototype amplifier mechanical design  

SciTech Connect

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

Horvath, J.

1996-10-01

220

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

221

An Amplified Sensitivity Arising from Covalent Modification in Biological Systems  

Microsoft Academic Search

The transient and steady-state behavior of a reversible covalent modification system is examined. When the modifying enzymes operate outside the region of first-order kinetics, small percentage changes in the concentration of the effector controlling either of the modifying enzymes can give much larger percentage changes in the amount of modified protein. This amplification of the response to a stimulus can

Albert Goldbeter; Daniel E. Koshland

1981-01-01

222

HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.  

SciTech Connect

Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department.

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

2005-08-21

223

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

224

Sensitivity Analysis of Combustion Timing of Homogeneous  

E-print Network

Sensitivity Analysis of Combustion Timing of Homogeneous Charge Compression Ignition Gasoline to predict the start of combustion in a homogeneous charge compression ignition (HCCI) engine. Qualitative idea of homogeneous charge compression ignition HCCI engines is the autoignition of a homogeneous

Stefanopoulou, Anna

225

High power RF solid state power amplifier system  

NASA Technical Reports Server (NTRS)

A high power, high frequency, solid state power amplifier system includes a plurality of input multiple port splitters for receiving a high-frequency input and for dividing the input into a plurality of outputs and a plurality of solid state amplifier units. Each amplifier unit includes a plurality of amplifiers, and each amplifier is individually connected to one of the outputs of multiport splitters and produces a corresponding amplified output. A plurality of multiport combiners combine the amplified outputs of the amplifiers of each of the amplifier units to a combined output. Automatic level control protection circuitry protects the amplifiers and maintains a substantial constant amplifier power output.

Sims, III, William Herbert (Inventor); Chavers, Donald Gregory (Inventor); Richeson, James J. (Inventor)

2011-01-01

226

Charge recombination reduction in dye-sensitized solar cells by means of an electron beam-deposited TiO 2 buffer layer between conductive glass and photoelectrode  

Microsoft Academic Search

A thin anatase titanium dioxide compact film was deposited by electron beam evaporation as buffer layer between the conductive transparent electrode and the porous TiO2-based photoelectrode in dye-sensitized solar cells. The effect of such a buffer layer on the back transfer reaction of electrons to tri-iodide ions in liquid electrolyte-based cells has been studied by means of both electrochemical impedance

Michele Manca; Francesco Malara; Luigi Martiradonna; Luisa De Marco; Roberto Giannuzzi; Roberto Cingolani; Giuseppe Gigli

2010-01-01

227

Inverting Amplifier with Current Input  

NSDL National Science Digital Library

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

2009-11-23

228

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

229

Spacecraft Charging and Mitigation  

NASA Astrophysics Data System (ADS)

Satellites and spacecraft materials can become charged to tens or even thousands of volts when ions in the space environment collide with spacecraft. This can sometimes cause electrical discharge of differentially or internally charged spacecraft materials, which can adversely affect satellite operations. Additionally, high-energy ions can penetrate spacecraft materials and deposit their energy within sensitive electronics, causing component damage or failure. To consider various approaches for spacecraft charge mitigation, 150 technologists from around the world representing government, academia, and industry met at the 11th Spacecraft Charging Technology Conference (SCTC) in Albuquerque, N. M., on 20-24 September 2010. The conference was held against the backdrop of the apparent charging event of the Galaxy 15 satellite, which some speculate triggered this geosynchronous communications satellite to cease operations, thereby adversely affecting related satellite-reliant communities (see J. Allen, Space Weather, 8, S06008, doi:10.1029/2010SW000588, 2010)

Denig, William; Cooke, David; Ferguson, Dale

2010-10-01

230

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

Microsoft Academic Search

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

ELIZABETH VALENTINE-THON

231

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

Microsoft Academic Search

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

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

2004-01-01

232

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

233

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

234

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

235

Enhanced charge transportation in a polypyrrole counter electrode via incorporation of reduced graphene oxide sheets for dye-sensitized solar cells.  

PubMed

In this work, reduced graphene oxide (RGO) sheets are successfully introduced into the conductive polypyrrole (PPy) matrix as conductive channels and co-catalyst, through simple incorporation of graphene oxide (GO) into PPy and subsequent in situ reduction from GO/PPy to RGO/PPy composite film. The RGO/PPy film is fabricated as a counter electrode for dye-sensitized solar cells, and it exhibits excellent catalytic performance for reduction of triiodide. For this reason, the incorporated RGO sheets significantly improve short-circuit photocurrent density from 14.27 to 15.81 mA cm(-2) and power conversion efficiency from 7.11% to 8.14%, which is comparable with that for the cell based on a Pt cathode. PMID:23171993

Gong, Feng; Xu, Xin; Zhou, Gang; Wang, Zhong-Sheng

2013-01-14

236

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

237

Retrodiction for optical attenuators, amplifiers, and detectors  

SciTech Connect

The transformation that an attenuator makes on the state of an optical field is the time reverse of that of an amplifier. Thus predicting the output state for an amplifier is equivalent to retrodicting the input state of an attenuator. We explore the consequences of this equivalence for simple optical quantum communication channels. One counterintuitive consequence is that the mean number of photons sent into an amplifier as retrodicted from a measurement of the number of output photons does not include the contribution of the amplifier noi0008.

Jedrkiewicz, Ottavia; Loudon, Rodney [Department of Electronic Systems Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Jeffers, John [Department of Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG (United Kingdom)

2004-09-01

238

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 amplifer circuit includes a first operational amplifier with a first feedback loop which includes a second, inverting operational amplifier in a second feedstock loop. The compensated output signal is provided by the second operational amplifier with the log elements, i.e., resistors, and the compensating capacitors in each of the feedback loops having equal values so that each break point is offset by a compensating break point or zero.

Brookshier, W.

1985-02-08

239

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

240

Free randomness can be amplified  

E-print Network

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

Roger Colbeck; Renato Renner

2011-05-16

241

Wavelength swept amplified spontaneous emission source.  

PubMed

We present a new, alternative approach to realize a wavelength swept light source with no fundamental limit to sweep speed. Amplified spontaneous emission (ASE) light alternately passes a cascade of optical gain elements and tunable optical bandpass filters. We show that for high sweep speeds, the control signal for the different filters has to be applied with a defined, precise phase delay on the order of nanoseconds, to compensate for the light propagation time between the filters and ensure optimum operation. At a center wavelength of 1300 nm sweep rates of 10 kHz, 100 kHz and 340 kHz over a sweep range of 100 nm full width and an average power of 50 mW are demonstrated. For application in optical coherence tomography (OCT), an axial resolution of 12 microm (air), a sensitivity of 120 dB (50 mW) and a dynamic range of 50 dB are achieved and OCT imaging is demonstrated. Performance parameters like coherence properties and relative intensity noise (RIN) are quantified, discussed and compared to the performance of Fourier Domain Mode Locked (FDML) lasers. Physical models for the observed difference in performance are provided. PMID:20372613

Eigenwillig, Christoph M; Biedermann, Benjamin R; Wieser, Wolfgang; Huber, Robert

2009-10-12

242

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

243

Allelic dilution obscures detection of a biologically significant resistance mutation in EGFR-amplified lung cancer  

PubMed Central

EGFR is frequently mutated and amplified in lung adenocarcinomas sensitive to EGFR inhibitors gefitinib and erlotinib. A secondary mutation, T790M, has been associated with acquired resistance but has not been shown to be sufficient to render EGFR mutant/amplified lung cancers resistant to EGFR inhibitors. We created a model for studying acquired resistance to gefitinib by prolonged exposure of a gefitinib-sensitive lung carcinoma cell line (H3255; EGFR mutated and amplified) to gefitinib in vitro. The resulting resistant cell line acquired a T790M mutation in a small fraction of the amplified alleles that was undetected by direct sequencing and identified only by a highly sensitive HPLC-based technique. In gefitinib-sensitive lung cancer cells with EGFR mutations and amplifications, exogenous introduction of EGFR T790M effectively conferred resistance to gefitinib and continued ErbB-3/PI3K/Akt signaling when in cis to an activating mutation. Moreover, continued activation of PI3K signaling by the PIK3CA oncogenic mutant, p110? E545K, was sufficient to abrogate gefitinib-induced apoptosis. These findings suggest that allelic dilution of biologically significant resistance mutations may go undetected by direct sequencing in cancers with amplified oncogenes and that restoration of PI3K activation via either a T790M mutation or other mechanisms can provide resistance to gefitinib. PMID:16906227

Engelman, Jeffrey A.; Mukohara, Toru; Zejnullahu, Kreshnik; Lifshits, Eugene; Borras, Ana M.; Gale, Christopher-Michael; Naumov, George N.; Yeap, Beow Y.; Jarrell, Emily; Sun, Jason; Tracy, Sean; Zhao, Xiaojun; Heymach, John V.; Johnson, Bruce E.; Cantley, Lewis C.; Janne, Pasi A.

2006-01-01

244

Direct solar-pumped iodine laser amplifier  

Microsoft Academic Search

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

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

1986-01-01

245

Signal flow graph analysis of feedback amplifiers  

Microsoft Academic Search

A systematic way of transcribing the schematic of an integrated circuit into its signal flow graph (SFG) equivalent is presented. With this SFG, transfer functions, loop gains, and input and output impedances are readily computed. The analysis is valid for multiloop amplifiers and the computation of a three-stage amplifier with nested Miller compensation is presented to illustrate the robustness of

Wing-Hung Ki

2000-01-01

246

PHASE NOISE IN MICROWAVE OSCILLATORS AND AMPLIFIERS  

E-print Network

class AB power amplifier. iv #12;Dedication To my parents for their love and endless support #12 of oscillators and power amplifiers. Next, a design method for voltage controlled oscillators (VCOs) with si- multaneous small size, low phase noise, DC power consumption and thermal drift is presented. Design steps

Popovic, Zoya

247

Stability problems in transistor power amplifiers  

Microsoft Academic Search

For devices to be useful, they must be applied in circuits. Expensive power transistors can be destroyed by undesired oscillations and instabilities. Furthermore, troublesome unwanted spurious frequencies must be avoided. The problem of stability is complicated by the fact that a class C amplifier represents the superposition of a linear class A amplifier and a nonlinear instabilities can occur. This

OTWARD MULLER; WILLIAM G. FIGEL

1967-01-01

248

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

249

Post pulse shutter for laser amplifier  

DOEpatents

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

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

1981-03-17

250

Quantum metrology with parametric amplifier-based photon correlation interferometers.  

PubMed

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

251

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

252

Charged Condensation  

E-print Network

We consider Bose-Einstein condensation of massive electrically charged scalars in a uniform background of charged fermions. We focus on the case when the scalar condensate screens the background charge, while the net charge of the system resides on its boundary surface. A distinctive signature of this substance is that the photon acquires a Lorentz-violating mass in the bulk of the condensate. Due to this mass, the transverse and longitudinal gauge modes propagate with different group velocities. We give qualitative arguments that at high enough densities and low temperatures a charged system of electrons and helium-4 nuclei, if held together by laboratory devices or by force of gravity, can form such a substance. We briefly discuss possible manifestations of the charged condensate in compact astrophysical objects.

Gregory Gabadadze; Rachel A. Rosen

2007-06-15

253

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

254

Variability in the pattern of random amplified polymorphic DNA.  

PubMed

The random amplified polymorphic DNA (RAPD) technique is a simple method to detect DNA polymorphism. It is sensitive to reaction conditions. Small changes in the reactants' concentration cause variations in amplification products. Using DNA from Asparagus officinalis, Dactylis glomerata, Mercurialis annua and Escherichia coli, we examined variability in the amplification pattern associated with reaction constituents. An increase in the ratio of Taq DNA polymerase to DNA in the reaction increased the number of amplified fragments. Increasing the concentration of primer resulted in the amplification of low molecular weight DNA fragments, while lowering the concentration resulted in high molecular weight fragments. Subsets of amplified fragments required different concentrations of magnesium for their highest intensity. Mechanical shearing of DNA obtained by sonication led to reduction in amplification of a subset of products. Enzymatic fragmentation of DNA by restriction enzymes led to loss or gain of specific fragments, depending on the DNA, primer, and restriction enzyme. RAPD markers of pooled DNA of anonymous pedigree should be critically evaluated for frequent 'false positive' markers. PMID:9504820

Khandka, D K; Tuna, M; Tal, M; Nejidat, A; Golan-Goldhirsh, A

1997-12-01

255

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

256

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

257

21 CFR 882.1835 - Physiological signal amplifier.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Physiological signal amplifier. 882.1835 Section 882.1835... § 882.1835 Physiological signal amplifier. (a) Identification. A physiological signal amplifier is a general purpose device used...

2010-04-01

258

21 CFR 882.1835 - Physiological signal amplifier.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Physiological signal amplifier. 882.1835 Section 882.1835... § 882.1835 Physiological signal amplifier. (a) Identification. A physiological signal amplifier is a general purpose device used...

2012-04-01

259

21 CFR 882.1835 - Physiological signal amplifier.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Physiological signal amplifier. 882.1835 Section 882.1835... § 882.1835 Physiological signal amplifier. (a) Identification. A physiological signal amplifier is a general purpose device used...

2011-04-01

260

47 CFR 2.815 - External radio frequency power amplifiers.  

Code of Federal Regulations, 2012 CFR

... External radio frequency power amplifiers. 2.815 Section 2.815 ...External radio frequency power amplifiers. (a) As used in this part, an external radio frequency power amplifier is any device which,...

2012-10-01

261

Cavity enhanced rephased amplified spontaneous emission  

E-print Network

Amplified spontaneous emission is usually treated as an incoherent noise process. Recent theoretical and experimental work using rephasing optical pulses has shown that rephased amplified spontaneous emission (RASE) is a potential source of wide bandwidth time-delayed entanglement. Due to poor echo efficiency the plain RASE protocol doesn't in theory achieve perfect entanglement. Experiments done to date show a very small amount of entanglement at best. Here we show that rephased amplified spontaneous emission can, in principle, produce perfect multimode time-delayed two mode squeezing when the active medium is placed inside a Q-switched cavity.

Lewis A Williamson; Jevon J Longdell

2014-03-26

262

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

263

Experimental design of laminar proportional amplifiers  

NASA Technical Reports Server (NTRS)

An experimental program was initiated at Langley Research Center to study the effects of various parameters on the design of laminar proportional beam deflection amplifiers. Matching and staging of amplifiers to obtain high-pressure gain was also studied. Variable parameters were aspect ratio, setback, control length, receiver distance, receiver width, width of center vent, and bias pressure levels. Usable pressure gains from 4 to 19 per stage can now be achieved, and five amplifiers were staged together to yield pressure gains up to 2,000,000.

Hellbaum, R. F.

1976-01-01

264

The 60 GHz solid state power amplifier  

NASA Technical Reports Server (NTRS)

A new amplifier architecture was developed during this contract that is superior to any other solid state approach. The amplifier produced 6 watts with 4 percent efficiency over a 2 GHz band at 61.5 GHz. The unit was 7 x 9 x 3 inches in size, 5.5 pounds in weight, and the conduction cooling through the baseplate is suitable for use in space. The amplifier used high efficiency GaAs IMPATT diodes which were mounted in 1-diode circuits, called modules. Eighteen modules were used in the design, and power combining was accomplished with a proprietary passive component called a combiner plate.

Mcclymonds, J.

1991-01-01

265

An Energy-Efficient Micropower Neural Recording Amplifier  

Microsoft Academic Search

This paper describes an ultralow-power neural recording amplifier. The amplifier appears to be the lowest power and most energy-efficient neural recording amplifier reported to date. We describe low-noise design techniques that help the neural amplifier achieve input-referred noise that is near the theoretical limit of any amplifier using a differential pair as an input stage. Since neural amplifiers must include

Woradorn Wattanapanitch; Michale Fee; Rahul Sarpeshkar

2007-01-01

266

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

267

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

268

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.

269

Erbium-doped phosphate fiber amplifiers  

NASA Astrophysics Data System (ADS)

In this paper, the development of phosphate glass fiber amplifier with a high gain per unit length is reviewed. The performance of compact multimode pumped erbium-doped phosphate fiber amplifiers is presented. A fiber amplifier with a small signal net gain of 41dB at 1535nm and 21dB over the full C-band was demonstrated using a newly developed 8-cm long erbium-doped phosphate fiber excited with a 1-W, 975-nm multimode laser diode. A theoretical model was developed for the multi-mode pumped amplifier based on modified rate equations and effective beam propagation method. Close agreement between experimental and modeling results is observed.

Jiang, Shibin

2003-08-01

270

High bandwidth differential amplifier for shock experiments.  

PubMed

We developed a high bandwidth differential amplifier for gas gun shock experiments of low-resistance metals. The circuit has a bandwidth up to 1 GHz, and is capable of measuring signals of ?1.5 V with a common mode rejection of 250 V. Conductivity measurements of gas gun targets are measured by flowing high currents through the targets. The voltage is measured across the target using a technique similar to a four-point probe. Because of the design of the current source and load, the target voltage is ?250 V relative to ground. Since the expected voltage change in the target is <1 V, the differential amplifier must have a large common mode rejection. Various amplifying designs are shown, although the increased amplification decreases bandwidth. Bench tests show that the amplifier can withstand significant common mode dc voltage and measure 10 ns, and 50 mV signals. PMID:23126892

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

2012-10-01

271

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

272

Operational Amplifier Experiments for the Chemistry Laboratory.  

ERIC Educational Resources Information Center

Provides details of experiments that deal with the use of operational amplifiers and are part of a course in instrumental analysis. These experiments are performed after the completion of a set of electricity and electronics experiments. (DDR)

Braun, Robert D.

1996-01-01

273

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

274

Direct solar-pumped iodine laser amplifier  

Microsoft Academic Search

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

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

1989-01-01

275

A single power supply optoelectronic differential amplifier  

E-print Network

A SINGLE POWER SUPPLY OPTOELECTRONIC DIFFERENTIAL AMPLIFIER A Thesis by YOUNGiXIIN ALBERT CHOI Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December...A SINGLE POWER SUPPLY OPTOELECTRONIC DIFFERENTIAL AMPLIFIER A Thesis by YOUNGiXIIN ALBERT CHOI Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December...

Choi, Youngmin Albert

2012-06-07

276

Ka-band monolithic gain control amplifier  

NASA Technical Reports Server (NTRS)

A monolithic gain control amplifier for Ka-band has been developed based on 0.25 micron-gate-length dual-gate FETs fabricated on ion-implanted material. A single-stage monolithic amplifier gives a gain of 6 dB at 31 GHz including fixture losses with a gain control range of over 20 dB. The device and IC design and fabrication are described.

Geddes, J.; Sokolov, V.; Contolatis, T.

1986-01-01

277

Novel Design Procedure for Class Power Amplifiers  

Microsoft Academic Search

This paper presents a novel design procedure for the class-EM amplifier. The numerical design procedure is applied to the design of the class-EM amplifier, which achieves simple and accurate designs for high-order circuits. As a result, no tuning process is necessary in the circuit implementations. In this paper, two types of auxiliary circuits are considered, namely, the zero-voltage switching class-E

Ryosuke Miyahara; Hiroo Sekiya; Marian K. Kazimierczuk

2010-01-01

278

OPASYN: a compiler for CMOS operational amplifiers  

Microsoft Academic Search

A silicon compilation system for CMOS operational amplifiers (OPASYN) is discussed. The synthesis system takes as inputs system-level specifications, fabrication-dependent technology parameters, and geometric layout rules. It produces a design-rule-correct compact layout of an optimized operational amplifier. The synthesis proceeds in three stages: (1) heuristic selection of a suitable circuit topology; (2) parametric circuit optimization based on analytic models; and

Han Young Koh; Carlo H. Séquin; Paul R. Gray

1990-01-01

279

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

280

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

PubMed

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

Ghosh, Shalini; Guchhait, Nikhil

2009-07-13

281

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

282

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

283

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

284

Experimental temperature measurements for the energy amplifier test  

NASA Astrophysics Data System (ADS)

A uranium thermometer has been designed and built in order to make local power measurements in the First Energy Amplifier Test (FEAT). Due to the experimental conditions power measurements of tens to hundreds of nW were required, implying a sensitivity in the temperature change measurements of the order of 1 mK. A uranium thermometer accurate enough to match that sensitivity has been built. The thermometer is able to determine the absolute energetic gain obtained in a tiny subcritical uranium assembly exposed to a proton beam of kinetic energies between 600 MeV and 2.75 GeV. In addition, the thermometer measurements have provided information about the spatial power distribution and the shape of the neutron spallation cascade.

Calero, J.; Cennini, P.; Gallego, E.; Gálvez, J.; Tabares, L. García; González, E.; Jaren, J.; López, C.; Lorente, A.; Val, J. M. Martínez; Oropesa, J.; Rubbia, C.; Rubio, J. A.; Saldaña, F.; Tamarit, J.; Vieira, S.

1996-02-01

285

PHYSICAL REVIEW A 82, 033827 (2010) Noise figure of amplified dispersive Fourier transformation  

E-print Network

high frame rate and shutter speed, known as serial time-encoded amplified imaging or microscopy (STEAM. Following our earlier work on the theory of ADFT, here we study the effect of noise on ADFT. We derive-off between loss and dispersion, hence circumventing the loss of sensitivity at high speeds caused

Jalali. Bahram

286

Amplifying Limited Expert Input to Sanitize Large Network Traces Xin Huang, Fabian Monrose, Michael K. Reiter  

E-print Network

Amplifying Limited Expert Input to Sanitize Large Network Traces Xin Huang, Fabian Monrose, Michael data in packet payloads, motivated by the need to sanitize packets before releasing them (e. Keywords-sanitization; packet payloads; sensitive data I. INTRODUCTION Visibility into packet payloads

Reiter, Michael

287

Human evolution in a variable environment: the amplifier lakes of Eastern Africa  

Microsoft Academic Search

The development of the Cenozoic East African Rift System (EARS) profoundly re-shaped the landscape and significantly increased the amplitude of short-term environmental response to climate variation. In particular, the development of amplifier lakes in rift basins after three million years ago significantly contributed to the exceptional sensitivity of East Africa to climate change compared to elsewhere on the African continent.

Martin H. Trauth; Mark A. Maslin; Alan L. Deino; Annett Junginger; Moses Lesoloyia; Eric O. Odada; Daniel O. Olago; Lydia A. Olaka; Manfred R. Strecker; Ralph Tiedemann

2010-01-01

288

Thermal and moisture induced stressing effects of RF power amplifier modules  

Microsoft Academic Search

The trends in RF power amplifier (RFPA) modules for handsets are optimization of active device technology, circuit topology and packaging to enhance cost, size, performance, and ease of implementation. For the package in RFPA module manufacturing, device-to-board attach solder reflow condition and moisture sensitivity level (MSL) are the most challenging areas for further improvement in thermal management due to \\

Sangouk Lee; Minju Lee; D. S. Choi

2001-01-01

289

Molecular Evolution and Diversity inBacillus anthracisas Detected by Amplified Fragment Length Polymorphism Markers  

Microsoft Academic Search

Bacillus anthraciscauses anthrax and represents one of the most molecularly monomorphic bacteria known. We have used AFLP (amplified fragment length polymorphism) DNA markers to analyze 78 B. anthracis isolates and six relatedBacillusspecies for molecular variation. AFLP markers are extremely sensitive to even small sequence variation, using PCR and high-resolution electrophoresis to examine restriction fragments. Using this approach, we examined ca.

PAUL KEIM; ABDULAHI KALIF; JAMES SCHUPP; KAREN HILL; STEVEN E. TRAVIS; KARA RICHMOND; DEBRA M. ADAIR; MARTIN HUGH-JONES; CHERYL R. KUSKE; ANDPAUL JACKSON

1997-01-01

290

A gold nanoparticle-based chronocoulometric DNA sensor for amplified detection of DNA  

Microsoft Academic Search

We report a protocol for the amplified detection of target DNA by using a chronocoulometric DNA sensor (CDS). Electrochemistry is known to be rapid, sensitive and cost-effective; it thus offers a promising approach for DNA detection. Our CDS protocol is based on a 'sandwich' detection strategy, involving a capture probe DNA immobilized on a gold electrode and a reporter probe

Jiong Zhang; Shiping Song; Lihua Wang; Dun Pan; Chunhai Fan

2007-01-01

291

CHARGE syndrome  

Microsoft Academic Search

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

Kim D Blake; Chitra Prasad

2006-01-01

292

Charge Challenge  

NSDL National Science Digital Library

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

Kansas, University O.

2006-01-01

293

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

294

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

295

Neratinib overcomes trastuzumab resistance in HER2 amplified breast cancer  

PubMed Central

Trastuzumab has been shown to improve the survival outcomes of HER2 positive breast cancer patients. However, a significant proportion of HER2-positive patients are either inherently resistant or develop resistance to trastuzumab. We assessed the effects of neratinib, an irreversible panHER inhibitor, in a panel of 36 breast cancer cell lines. We further assessed its effects with or without trastuzumab in several sensitive and resistant breast cancer cells as well as a BT474 xenograft model. We confirmed that neratinib was significantly more active in HER2-amplified than HER2 non-amplified cell lines. Neratinib decreased the activation of the 4 HER receptors and inhibited downstream pathways. However, HER3 and Akt were reactivated at 24 hours, which was prevented by the combination of trastuzumab and neratinib. Neratinib also decreased pHER2 and pHER3 in acquired trastuzumab resistant cells. Neratinib in combination with trastuzumab had a greater growth inhibitory effect than either drug alone in 4 HER2 positive cell lines. Furthermore, trastuzumab in combination with neratinib was growth inhibitory in SKBR3 and BT474 cells which had acquired resistance to trastuzumab as well as in a BT474 xenograft model. Innately trastuzumab resistant cell lines showed sensitivity to neratinib, but the combination did not enhance response compared to neratinib alone. Levels of HER2 and phospho-HER2 showed a direct correlation with sensitivity to neratinib. Our data indicate that neratinib is an effective anti-HER2 therapy and counteracted both innate and acquired trastuzumab resistance in HER2 positive breast cancer. Our results suggest that combined treatment with trastuzumab and neratinib is likely to be more effective than either treatment alone for both trastuzumab-sensitive breast cancer as well as HER2-positive tumors with acquired resistance to trastuzumab. PMID:24009064

Mullooly, Maeve; Bennett, Ruth; Bouguern, Noujoude; Pedersen, Kasper; O'Brien, Neil A; Roxanis, Ioannis; Li, Ji-Liang; Bridge, Esther; Finn, Richard; Slamon, Dennis; McGowan, Patricia; Duffy, Michael J.

2013-01-01

296

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

297

READOUT ASIC FOR 3D POSITION-SENSITIVE DETECTORS.  

SciTech Connect

We describe an application specific integrated circuit (ASIC) for 3D position-sensitive detectors. It was optimized for pixelated CZT sensors, and it measures, corresponding to an ionizing event, the energy and timing of signals from 121 anodes and one cathode. Each channel provides low-noise charge amplification, high-order shaping, along with peak- and timing-detection. The cathode's timing can be measured in three different ways: the first is based on multiple thresholds on the charge amplifier's voltage output; the second uses the threshold crossing of a fast-shaped signal; and the third measures the peak amplitude and timing from a bipolar shaper. With its power of 2 mW per channel the ASIC measures, on a CZT sensor Connected and biased, charges up to 100 fC with an electronic resolution better than 200 e{sup -} rms. Our preliminary spectral measurements applying a simple cathode/mode ratio correction demonstrated a single-pixel resolution of 4.8 keV (0.72 %) at 662 keV, with the electronics and leakage current contributing in total with 2.1 keV.

DE GERONIMO,G.; VERNON, E.; ACKLEY, K.; DRAGONE, A.; FRIED, J.; OCONNOR, P.; HE, Z.; HERMAN, C.; ZHANG, F.

2007-10-27

298

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

299

Grains charges in interstellar clouds  

NASA Technical Reports Server (NTRS)

The charge of cosmic grains could play an important role in many astrophysical phenomena. It probably has an influence on the coagulation of grains and more generally on grain-grain collisions, and on interaction between charged particles and grains which could lead to the formation of large grains or large molecules. The electrostatic charge of grains depends mainly on the nature of constitutive material of the grain and on the physical properties of its environment: it results from a delicate balance between the plasma particle collection and the photoelectron emission, both of them depending on each other. The charge of the grain is obtained in two steps: (1) using the numerical model the characteristics of the environment of the grain are computed; (2) the charge of a grain which is embedded in this environment is determined. The profile of the equilibrium charge of some typical grains through different types of interstellar clouds is obtained as a function of the depth of the cloud. It is shown that the grain charge can reach high values not only in hot diffuse clouds, but also in clouds with higher densities. The results are very sensitive to the mean UV interstellar radiation field. Three parameters appear to be essential but with different levels of sensitivity of the charge: the gas density, the temperature, and the total thickness of the cloud.

Bel, N.; Lafon, J. P.; Viala, Y. P.

1989-01-01

300

Effect of amplified spontaneous emission on semiconductor optical amplifier based all-optical logic  

NASA Astrophysics Data System (ADS)

The performances of all-optical logic gates XOR, AND, OR, NOR and NAND based on semiconductor optical amplifier (SOA) have been simulated including the effects of amplified spontaneous emission (ASE). For the parameters used, all-optical logic gates using SOA are capable of operating at speed of 80 Gb/s.

Kotb, A.; Ma, S.; Chen, Z.; Dutta, N. K.; Said, G.

2011-12-01

301

Injection- Seeded Optoplasmonic Amplifier in the Visible  

PubMed Central

A hybrid optoplasmonic amplifier, injection-seeded by an internally-generated Raman signal and operating in the visible (563–675?nm), is proposed and evidence for amplification is presented. Comprising a gain medium tethered to a whispering gallery mode (WGM) resonator with a protein, and a plasmonic surface, the optical system described here selectively amplifies a single (or a few) Raman line(s) produced within the WGM resonator and is well-suited for routing narrowband optical power on-a-chip. Over the past five decades, optical oscillators and amplifiers have typically been based on the buildup of the field from the spontaneous emission background. Doing so limits the temporal coherence of the output, lengthens the time required for the optical field intensity to reach saturation, and often is responsible for complex, multiline spectra. In addition to the spectral control afforded by injection-locking, the effective Q of the amplifier can be specified by the bandwidth of the injected Raman signal. This characteristic contrasts with previous WGM-based lasers and amplifiers for which the Q is determined solely by the WGM resonator. PMID:25156810

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

2014-01-01

302

Injection- Seeded Optoplasmonic Amplifier in the Visible  

NASA Astrophysics Data System (ADS)

A hybrid optoplasmonic amplifier, injection-seeded by an internally-generated Raman signal and operating in the visible (563-675 nm), is proposed and evidence for amplification is presented. Comprising a gain medium tethered to a whispering gallery mode (WGM) resonator with a protein, and a plasmonic surface, the optical system described here selectively amplifies a single (or a few) Raman line(s) produced within the WGM resonator and is well-suited for routing narrowband optical power on-a-chip. Over the past five decades, optical oscillators and amplifiers have typically been based on the buildup of the field from the spontaneous emission background. Doing so limits the temporal coherence of the output, lengthens the time required for the optical field intensity to reach saturation, and often is responsible for complex, multiline spectra. In addition to the spectral control afforded by injection-locking, the effective Q of the amplifier can be specified by the bandwidth of the injected Raman signal. This characteristic contrasts with previous WGM-based lasers and amplifiers for which the Q is determined solely by the WGM resonator.

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

2014-08-01

303

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

304

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

305

Single event mirroring and sense amplifier designs for enhanced SE tolerance of DRAMs  

SciTech Connect

This paper investigates the applicability of existing SRAM SEU hardening techniques to conventional CMOS cross-coupled sense amplifiers used in DRAM structures. We propose a novel SEU mirroring concept and implementation for hardening DRAMs to bitline hits. Simulations indicate a 24-fold improvement in critical charge during the sensing state using a 10K T-Resistor scheme and a 28-fold improvement during the highly susceptible high impedance state using 2pF dynamic capacitance coupling.

Gulati, K.; Massengill, L.W. [Vanderbilt Univ., Nashville, TN (United States). Dept. of Electrical Engineering

1994-05-01

306

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

307

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

PubMed

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

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

2011-01-01

308

A high sensitivity ultra-low temperature RF conductance and noise measurement setup  

E-print Network

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

Parmentier, François D; Denis, Anne; Berroir, Jean-Marc; Glattli, D Christian; Plaçais, Bernard; Fève, Gwendal

2010-01-01

309

QED in arbitrary linear media: amplifying media  

E-print Network

Recently, we have developed a unified approach to QED in arbitrary linearly responding media in equilibrium--media that give rise to absorption [Phys. Rev. A \\textbf{75}, (2007) 053813]. In the present paper we show that, under appropriate conditions, the theory can be quite naturally generalized to amplifying media the effect of which is described within the framework of linear response theory. We discuss the limits of validity of the generalized theory and make contact with earlier quantization schemes suggested for the case of linearly and locally responding amplifying dielectric-type media. To illustrate the theory, we present the electromagnetic-field correlation functions that determine the Casimir force in the presence of amplifying media.

Christian Raabe; Dirk-Gunnar Welsch

2007-10-15

310

Cavity enhanced rephased amplified spontaneous emission  

NASA Astrophysics Data System (ADS)

Amplified spontaneous emission is usually treated as an incoherent noise process. Recent theoretical and experimental work using rephasing optical pulses has shown that rephased amplified spontaneous emission (RASE) is a potential source of wide bandwidth time-delayed entanglement. Due to poor echo efficiency the plain RASE protocol does not in theory achieve perfect entanglement. Experiments done to date show a very small amount of entanglement at best. Here we show that RASE can, in principle, produce perfect multimode time-delayed two mode squeezing when the active medium is placed inside a Q-switched cavity.

Williamson, Lewis A.; Longdell, Jevon J.

2014-07-01

311

Optimization of a high efficiency FEL amplifier  

E-print Network

The problem of an efficiency increase of an FEL amplifier is now of great practical importance. Technique of undulator tapering in the post-saturation regime is used at the existing x-ray FELs LCLS and SACLA, and is planned for use at the European XFEL, Swiss FEL, and PAL XFEL. There are also discussions on the future of high peak and average power FELs for scientific and industrial applications. In this paper we perform detailed analysis of the tapering strategies for high power seeded FEL amplifiers. Application of similarity techniques allows us to derive universal law of the undulator tapering.

Schneidmiller, E A

2014-01-01

312

Nondeterministic Amplifier for Two Photon Superpositions  

E-print Network

We examine heralded nondeterministic noiseless amplification based on the quantum scissors device, which has been shown to increase the one-photon amplitude of a state at the expense of the vacuum-state amplitude. Here we propose using the same basic design to perform perfect amplification in a basis set of up to two photons. The device is much more efficient than several one-photon amplifiers working in tandem. When used to amplify coherent states this advantage is shown using either fidelity or in terms of probability of sucessful action, or more strikingly in a combination of the two.

John Jeffers

2010-12-14

313

Noise figure of amplified dispersive Fourier transformation  

SciTech Connect

Amplified dispersive Fourier transformation (ADFT) is a powerful tool for fast real-time spectroscopy as it overcomes the limitations of traditional optical spectrometers. ADFT maps the spectrum of an optical pulse into a temporal waveform using group-velocity dispersion and simultaneously amplifies it in the optical domain. It greatly simplifies spectroscopy by replacing the diffraction grating and detector array in the conventional spectrometer with a dispersive fiber and single-pixel photodetector, enabling ultrafast real-time spectroscopic measurements. Following our earlier work on the theory of ADFT, here we study the effect of noise on ADFT. We derive the noise figure of ADFT and discuss its dependence on various parameters.

Goda, Keisuke; Jalali, Bahram [Electrical Engineering Department, University of California, Los Angeles, California 90095 (United States)

2010-09-15

314

Erbium Fiber Amplifiers in Linear Lightwave Transmission  

Microsoft Academic Search

\\u000a The invention and development of fibers doped with rare-earth element as in-line optical amplifiers [223, 224, 225, 226] were\\u000a a major breakthrough that enabled great enhancement in the capability of fiber optic telecommunication networks. With their\\u000a ubiquitous deployment in digital fiber-optic networks, these fiber amplifiers have met the test of time for their proven values.\\u000a However, their employment in linear lightwave systems, including

Kam Lau

315

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).

Muller, Eric

1995-01-01

316

Novel non-chemically amplified (n-CARs) negative resists for EUVL  

NASA Astrophysics Data System (ADS)

We report the lithography performance of novel non chemical amplified (n-CARS) negative photoresist materials which are accomplished by homopolymers and copolymers that are prepared from monomers containing sulfonium groups. The latter have long been found to be sensitive to UV radiation and undergo polarity change on exposure. For this reason, these groups were chosen as radiation sensitive groups in non- CARs that are discussed herein. Novel n-CAR negative resists were synthesized and characterized for EUVL applications, as they are directly sensitive to radiation without utilizing the concept of chemical amplification. The n-CARs achieved 20 and 16 nm L/2S, L/S patterns to meet the ITRS requirements. We will also discuss the sensitivity and LER of these negative n-CARS to e-beam irradiation which will provide a basis for EUVL down to the 16 nm node and below. These new negative tone resist provide a viable path forward for designing non- chemically amplified resists that can obtain higher resolutions than current chemically amplified resists at competitive sensitivities.

Singh, Vikram; Satyanarayana, V. S. V.; Sharma, Satinder K.; Ghosh, Subrata; Gonsalves, Kenneth E.

2014-03-01

317

Enzyme-amplified aequorin-based bioluminometric hybridization assays.  

PubMed

The sensitivity of aequorin-based bioluminometric hybridization assays was enhanced by introducing, enzymically, multiple aequorin labels per DNA hybrid. The target DNA was hybridized in microtiter wells with an immobilized capture probe and a digoxigenin-labeled detection probe. The hybrids were reacted with an anti-digoxigenin antibody conjugated to horseradish peroxidase. Peroxidase catalyzed the oxidation of digoxigenin-tyramine by hydrogen peroxide, resulting in the attachment of multiple digoxigenin moieties to the solid phase. Aequorin-labeled anti-digoxigenin antibody was then allowed to bind to the immobilized digoxigenins. The bound aequorin was determined by its characteristic Ca2+-triggered bioluminescence. As low as 20 fmol/L (1 amol/ well) target DNA was detected with a signal-to-background ratio of 2.7. A hybridization assay that used only aequorin-labeled anti-digoxigenin antibody without the peroxidase amplification step gave a signal-to-background ratio of 2 for 160 fmol/L target DNA. The signal enhancement of the amplified assay was in the range of 14-38 times. The analytical range of the amplified assay extended up to 2600 fmol/L. The CVs were in the range of 5.5-7.3%. PMID:11217784

Laios, E; Ioannou, P C; Christopoulos, T K

2001-02-01

318

Sensitive Agent: Sensitive Agent  

E-print Network

social interaction must be simulated. Conventional agents already have rich communication skills including nonverbal communication; however, lack the sensitivity that is necessary for social interaction-78. [13] MIT, Affective Computing, http://affect.media.mit.edu/AC_affect.html [14] Helmut Prendinger

Nakanishi, Hideyuki

319

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

320

Thermoacoustic Stirling Engine --An acoustic amplifier  

E-print Network

Thermoacoustic Stirling Engine -- An acoustic amplifier: ambient heat exchanger (water) stacked kW sound hot diesel exhaust hot diesel exhaust 34" 24" Thermoacoustic Stirling Engine -- An acoustic@lanl.gov 505-667-7545 A lighter, smaller, faster, cheaper version of free-piston Stirling 500W Lightweight

Lee, Dongwon

321

Research on fluidics, valves, and proportional amplifiers  

NASA Technical Reports Server (NTRS)

Research and development being conducted at the Systems and Controls Laboratory is reviewed. Static characteristics (supply, input, transfer, output, and noise characteristics) of laminar proportional amplifiers were investigated. Other topics discussed include velocity profiles for laminar fluidic jets, speed control systems employing a jet pipe valve, and power amplification with a vortex valve.

1974-01-01

322

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

323

EDFA amplified MSK optical transmission system  

NASA Astrophysics Data System (ADS)

This paper presents the performance and compatibility of optical signal amplification using a high gain, low noise figure, Erbium-Doped Fiber Amplifier (EDFA) with linear Minimum Shift Keying (MSK) modulation format for the transmission of DWDM signals in optical communication system.

Arya, Subhash C.; Arya, Shalini S.; Priye, Vishnu

2011-08-01

324

Emitter Follower Amplifier DC Analysis FREQ = 10000  

E-print Network

Emitter Follower Amplifier ­ DC Analysis C3 1n R1 30k Vcc 20Vdc C1 1n RL 500 Re 40k 0 Re1 200 Q2 Q2.97757mA re = 26/ IE = 26.597 (used later in ac analysis) For the emitter follower circuit and neglecting

Allen, Gale

325

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

326

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

327

Compression of amplified chirped optical pulses  

Microsoft Academic Search

A system is reported which transposes a short-pulse amplification technique employed in radar to the optical regime and that, in principle, should be capable of producing short (1 pc or less) pulses with energies at the Joule level. The technique involves stretching a chirped optical pulse and then amplifying it before recompression. To date, 2-ps pulses with an energy of

D. Strickland; G. Mourou

1985-01-01

328

Margin measurements in optical amplifier system  

Microsoft Academic Search

The margin, or the difference between the received signal-to-noise (SNR) and the SNR required to maintain a given bit error ratio (BER), is important to the design and operation of optical amplifier transmission systems A new tehnique is described for estimating the SNR at the receiver's decision circuit when the BER is too low to be measured in a reasonable

Neal S. Bergano; F. W. Kerfoot; C. R. Davidsion

1993-01-01

329

Dissolution kinetics of chemically amplified resists  

NASA Astrophysics Data System (ADS)

The dissolution rate characteristics of two typical DUV chemically amplified resists (negative resist A and positive resist B) were investigated, by comparing with an i-line novolac resist (resist C). The negative resist A here was based on crosslinking between phenolic resin and melamine derivatives, and the positive resist B was composed of tert-BOC protected phenolic resin.

Itani, Toshiro; Itoh, Katsuyuki; Kasama, Kunihiko

1993-09-01

330

Defibrillator-embedded rapid recovery electrocardiogram amplifier.  

PubMed

One of the most important performances of the defibrillator-embedded amplifier-monitor-recorder tract, connected to defibrillator electrodes, is its rapid recovery after the application of the shock pulse. Practically near-immediate restoration of the signal trace is mandatory for studies of post-shock effects on the myocardium. Automatic analysis of the electrocardiogram signal in public-access defibrillation, aiming for about 100% correct recognition of shockable and non-shockable rhythms, now requires fast amplifier settling, as the decision time should not exceed 10-20 s. Two circuits of post-shock amplifier transient suppressors were developed with non-linear feedback, resulting in second-order high-pass filtering, with gradual return to normally accepted first-order response. Simulation and testing in real conditions resulted in recovery periods in the range of 1-2 s for an amplifier tract of 1-30 Hz bandwidth, depending on the pulse waveform and electrode type. PMID:12851062

Neycheva, T; Krasteva, V

2003-01-01

331

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

2005-05-27

332

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

333

Direct Integration of Magnetoelectric Sensors with Microelectronics Improved Field Sensitivity, Signal-  

E-print Network

and piezopolymer PVDF were used as the model system), which are directly integrated with two different modes of low noise readout circuits charge mode and voltage mode. For the sensor system with charge mode readout Circuit PVDF Metglas Polarization Direction Vout=-qp/Cf Cf + Rf qp Cp Rp Sensor Charge Amplifier Gain

Yener, Aylin

334

Role of electrolytes on charge recombination in dye-sensitized TiO(2) solar cell (1): the case of solar cells using the I(-)/I(3)(-) redox couple.  

PubMed

Performance of dye-sensitized solar cells (DSCs) was investigated depending on the compositions of the electrolyte, i.e., the electrolyte with a different cation such as Li(+), tetra-n-butylammonium (TBA(+)), or 1,2-dimethyl-3-propylimidazolium (DMPIm(+)) in various concentrations, with and without 4-tert-butylpyridine (tBP), and with various concentrations of the I(-)/I(3)(-) redox couple. Current-voltage characteristics, electron lifetime, and electron diffusion coefficient were measured to clarify the effects of the constituents in the electrolyte on the charge recombination kinetics in the DSCs. Shorter lifetimes were found for the DSCs employing adsorptive cations of Li(+) and DMPIm(+) than for a less-adsorptive cation of TBA(+). On the other hand, the lifetimes were not influenced by the concentrations of the cations in the solutions. Under light irradiation, open-circuit voltages of DSCs decreased in the order of TBA(+)> DMPIm(+) > Li(+), and also decreased with the increase of [Li(+)]. The decreases of open-circuit voltage (V(oc)) were attributed to the positive shift of the TiO(2) conduction band potential (CBP) by the surface adsorption of DMPIm(+) and Li(+). These results suggest that the difference of the free energies between that of the electrons in the TiO(2) and of I(3)(-) has little influence on the electron lifetimes in the DSCs. The shorter lifetime with the adsorptive cations was interpreted with the thickness of the electrical double layer formed by the cations, and the concentration of I(3)(-) in the layer, i.e., TBA(+) formed thicker double layer resulting in lower concentration of I(3)(-) on the surface of the TiO(2). The addition of 4-tert-butylpyridine (tBP) in the presence of Li(+) or TBA(+) showed no significant influence on the lifetime. The increase of V(oc) by the addition of tBP into the electrolyte containing Li(+) and the I(-)/I(3)(-) redox couple was mainly attributed to the shift of the CBP back to the negative potential by reducing the amount of adsorbed Li cations. PMID:16851382

Nakade, Shogo; Kanzaki, Taisuke; Kubo, Wataru; Kitamura, Takayuki; Wada, Yuji; Yanagida, Shozo

2005-03-01

335

Design and implementation of low power multistage amplifiers and high frequency distributed amplifiers  

E-print Network

DESIGN AND IMPLEMENTATION OF LOW POWER MULTISTAGE AMPLIFIERS AND HIGH FREQUENCY DISTRIBUTED AMPLIFIERS A Thesis by CHINMAYA MISHRA Submitted to the Office of Graduate Studies of Texas A&M University in partial... A Thesis by CHINMAYA MISHRA Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: Edgar S?nchez-Sinencio (Chair of Committee...

Mishra, Chinmaya

2005-11-01

336

High performance building blocks for wireless receiver: multi-stage amplifiers and low noise amplifiers  

E-print Network

of Committee, Edgar S?nchez-Sinencio Committee Members, C?sar O. Malav? Weiping Shi Jos? Silva-Mart?nez Head of Department, Costas N. Georghiades December 2007 Major Subject: Electrical Engineering iii ABSTRACT High... Performance Building Blocks for Wireless Receiver: Multi-Stage Amplifiers and Low Noise Amplifiers. (December 2007) Xiaohua Fan, B.S., Tsinghua University; M.S., Chinese Academy of Sciences Chair of Advisory Committee: Dr. Edgar S...

Fan, Xiaohua

2009-05-15

337

Graphene-based charge sensors  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

338

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

339

CARM and harmonic gyro-amplifier experiments at 17 GHz.  

National Technical Information Service (NTIS)

Cyclotron resonance maser amplifiers are possible sources for applications such as electron cyclotron resonance heating of fusion plasmas and driving high-gradient rf linear accelerators. For accelerator drivers, amplifiers or phase locked-oscillators are...

W. L. Menninger, B. G. Danly, S. Alberti, C. Chen, J. L. Rullier

1993-01-01

340

Erbium-Doped Fiber Amplifier Elements for Structural Analysis Sensors.  

National Technical Information Service (NTIS)

The use of erbium-doped fiber amplifiers (EDFA's) in optical fiber sensor systems for structural analysis is described. EDFA's were developed for primary applications as periodic regenerator amplifiers in long-distance fiber-based communication systems. T...

P. Hanna-hawver K. D. Kamdar, S. Mehta, S. Nagarajan, M. H. Nasta

1992-01-01

341

To Charge or Not to Charge.  

ERIC Educational Resources Information Center

Ways to fund a publications office and the merits of charge-back systems are discussed. Every charge-back system differs. Some offices try to cover costs; others bill for overhead. Some alternatives to charging are described. (MLW)

Hay, Tina M.

1989-01-01

342

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

343

Charged membranes.  

PubMed

This Teaching Resource provides three animated lessons that describe the storage and utilization of energy across plasma membranes. The "Na,K ATPase" animation explains how these pumps establish the electrochemical gradient that stores energy across plasma membranes. The "ATP synthesizing complexes" animation shows how these complexes transfer energy from the inner mitochondrial membrane to adenosine triphosphate (ATP). The "action potential" lesson explains how charged membranes are used to propagate signals along the axons of neurons. These animations serve as valuable resources for any collegiate-level course that describes these important factors. Courses that might employ them include introductory biology, biochemistry, biophysics, cell biology, pharmacology, and physiology. PMID:23592845

Thatcher, Jack D

2013-01-01

344

Charge Equilibrium  

NASA Astrophysics Data System (ADS)

The mean equililibrium charge of a penetrating ion can be estimated on the basis of Bohr's velocity criterion or Lamb's energy criterion. Qualitative and quantitative results are derived on the basis of the Thomas-Fermi model of the atom, which is discussed explicitly. This includes a brief introduction to the Thomas-Fermi-Dirac model. Special attention is paid to trial function approaches by Lenz and Jensen as well as Brandt and Kitagawa. The chapter also offers a preliminary discussion of the role of the stopping medium, gas-solid differences, and a survey of data compilations.

Sigmund, Peter

345

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

346

Wave optics modelling of amplified spontaneous emission  

SciTech Connect

A laser works by amplified spontaneous emission (ASE) of inverted atomic ions confined in an amplifier of rod-like geometry, such that ASE radiation is directed out of both ends of the rod. The forward and backward ASE waves are coupled through the population-rate equations and cause the saturation of the lasing transition (gain saturation). Diffraction of the waves in the transverse direction is responsible for the radiation pattern (angular distribution) observed on a distant screen and for the degree of spatial coherence of the radiation. Refraction of the light also occurs due to spatial gradients in the electron density. In order to describe this situation a code has been developed which numerically solves paraxial Maxwell's equations in the time and two spatial dimensions. The code uses the Peaceman-Rachford Alternating-Direction-Implicit algorithm and is benchmarked against laboratory DYE-LASER experiments. 4 refs., 1 fig.

Ritchie, B.; Garrison, J.

1990-11-06

347

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

348

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

349

Fiber amplifier based UV laser source  

NASA Astrophysics Data System (ADS)

We demonstrate 30 W of average UV power, at 353 nm, by harmonically converting the output of a seeded cascade of fiber amplifiers operating at 1060 nm. The UV output represents 46% harmonic conversion efficiency from the fundamental beam. The all-fiber-amplifier, MOPA architecture supports variable pulse repetition frequencies and pulse widths. We demonstrate pulse repetition frequencies up to 2 MHz and pulse widths as short as 2 ns. Two bulk LBO crystals, oriented for second and third harmonic conversion, are used to obtain stable UV output power. A turnkey system using this architecture is commercially available. The system is entirely air-cooled and operates from a standard wall plug electric service, facilitating integration into various material processing applications.

Leonardo, Manuel J.; Byer, Mark W.; Keaton, Gregory L.; Richard, Derek J.; Adams, Frank J.; Nightingale, John L.; Arbore, Mark A.; Guzsella, Susi; Smoliar, Laura A.

2009-02-01

350

Radiographic amplifier screens: Fabrication process and characteristics  

NASA Technical Reports Server (NTRS)

The fabrication process and transfer characteristics for solid state radiographic image transducers (radiographic amplifier screens) is described. These screens were developed for use in real time nondestructive evaluation procedures that require large format radiographic images with contrast and resolution capabilities unavailable with conventional fluoroscopic screens. This work was directed toward screens usable for inmotion, on-line radiographic inspection by means of closed circuit television.

Szepesi, Z. P.

1977-01-01

351

Direct solar-pumped iodine laser amplifier  

Microsoft Academic Search

A XeCl laser pumped iodine laser oscillator was developed which will be incorporated into the Master Oscillator Power Amplifier (MOPA) system. The developed XeCl laser produces output energy of about 60 mJ per pulse. The pulse duration was about 10 nsec. The kinetic model for the solar-pumped laser was refined and the algorithm for the calculation of a set of

Kwang S. Han; In Heon Hwang; Khong Hon Kim; Larry V. Stock

1988-01-01

352

Novel 140 GHz gyro-TWT amplifier  

SciTech Connect

The authors have designed and are currently building a novel gyro-TWT amplifier at powers up to 100 kW at a frequency of 140 GHz. The electron beam will be provided by an existing MIG electron gun which has been previously used in gyrotron oscillator research at the 100 kW power level at 140 GHz. The gun operates at 65 kV and up to 8A with {nu}{sub {perpendicular}}/{nu}{sub {parallel}} equal to 1.5. The novel wave circuit consists of two facing mirrors with confocal profiles in the transverse direction and flat profiles in the longitudinal direction. The mode is Gaussian-like in the transverse direction. This cavity design effectively reduces the mode competition problem in conventional amplifiers from two dimensions to one dimension. Another advantage of this circuit is the relatively large circuit size, which improves power capacity. Preliminary calculations indicate that the linear gain is about 2.7 dB/cm with an efficiency exceeding 20%. The driver of the Gyro-TWT amplifier is a 95 GHz Varian EIO generator with 100 W peak output power. The amplifier also employs a confocal mode converter which launches a gaussian beam along the axis. The slot size of the cavity is optimized to have minimal operating mode loss while maximizing losses of competing modes. A preliminary experiment using an oscillator configuration has also been designed. The device could easily be scaled to 95 GHz to meet D.O.D. needs at that frequency.

Hu, W.; Kreischer, K.E.; Shapiro, M.; Temkin, R.J. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center

1996-12-31

353

Amplified spontaneous emission in quaterthiophene single crystals  

Microsoft Academic Search

The authors demonstrate amplified spontaneous emission (ASE) from quaterthiophene single crystals and study its behavior at low temperature. The room temperature photoluminescence exhibits line narrowing (spectral width down to 10 nm) at 553 nm for excitation fluence larger than 1 mJ cm-2. At low temperature (10 K), ASE is observed from two vibronic transitions at 510 nm (0-1) and 553

Marco Polo; Andrea Camposeo; Silvia Tavazzi; Luisa Raimondo; Peter Spearman; Antonio Papagni; Roberto Cingolani; Dario Pisignano

2008-01-01

354

Integrated SQUID linear amplifier design and simulation  

SciTech Connect

A linear cascade video amplifier capable of working from DC to about one GHz was designed, fabricated, and initially tested. Two asymmetric SQUIDs operating in push-pull are used to achieve linearity and to eliminate output offset. Decoupling of the Josephson oscilliation between the SQUIDs is accomplished by using a special low-pass resonant transformer. Simulation results are presented for three- and ten-junction SQUIDs.

Gershenson, M.

1985-03-01

355

Advanced Interaction Studies of Travelling Wave Amplifiers  

Microsoft Academic Search

The gain and electron beam-microwave interaction for a periodic rectangular grating slow wave Travelling Wave Tube (TWT) amplifier(J.Joe, L.Louis, J.Scharer, J.Booske, M. Basten, Phys. Plasmas, 1997 (Accepted for Publication).) and initial studies of multitone interaction in a helix TWT are presented. This research focusses on the low-voltage (<=10 kV) interaction in the backward wave regime for Ku-band range of frequencies.

L. J. Louis; J. E. Scharer; J. H. Booske; C. Armstrong

1997-01-01

356

High power fiber amplifiers for kilowatt fiber arrays  

Microsoft Academic Search

Continuous-wave fiber based master-oscillator power-amplifier has demonstrated output powers over 150 W from a robustly single-mode polarization maintaining fiber amplifier. The amplifier is designed for coherent beam combining to generate kilowatt class fiber arrays.

Dennis Hammons; Jesse Anderegg; Stephen Brosnan; Hiroshi Komini; M. Wickham

2003-01-01

357

A simple and fast transimpedance amplifier for microchannel plate detectors  

NASA Astrophysics Data System (ADS)

A simple and fast transimpedance amplifier to couple a microchannel plate detector with an oscilloscope with a low impedance input has been developed. The amplifier protects the connected electronic equipment from destructive high voltage bursts. Examples of the detection of electrons are shown. The influence of the amplifier on pulse shape and intensity is discussed.

Schwartze, P.; Baumgärtel, H.; Eisenhardt, C. G.

2001-07-01

358

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

359

Photonic bandgap fibre oscillators and amplifiers  

NASA Astrophysics Data System (ADS)

In the search for ever higher output power or energy from fibre oscillators or amplifiers a nowadays mature technology relies on enlarging the fibre mode area. Broadening of the core diameter, all other things being equal, inevitably yields a multimode fibre, thereby dramatically limiting the device usefulness. Various strategies have been deployed to design and manufacture single transverse mode fibre oscillators and amplifiers, among which making use of the so-called photonic bandgap effect to restrict the modal population seems promising. Helped by efficient and reliable numerical tools the design of large mode area singlemode photonic bandgap fibres is presented. Two fibres with 20-?m and 40-?m core diameter, both of them heavily doped with Yb 3+ ions, have been fabricated by the widespread modified chemical vapour deposition process and are shown to behave properly when used as the core element of either continuous wave oscillators or femtosecond amplifiers. Good output beam quality (M 2 parameter spanning from 1.12 to 1.5 for the set of fibres studied) and high slope efficiency of 80% in cw oscillation regime are demonstrated. Furthermore the 40-?m core diameter fibre is shown to be resilient to tight bending down to 7.5-cm radius. The stack-and-draw process makes it easy to tailor the outer cladding so that a large numerical aperture can be reached. Subsequently, from this air-clad fibre, 500 fs 47 W pulses at 35 MHz are obtained from a two-stage chirped pulse amplification system.

Février, S.; Gaponov, D.; Devautour, M.; Roy, P.; Daniault, L.; Hanna, M.; Papadopoulos, D. N.; Druon, F.; Georges, P.; Likhachev, M. E.; Salganskii, M. Y.; Yashkov, M. V.

2010-12-01

360

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

361

Stable spatial solitons in semiconductor optical amplifiers  

NASA Astrophysics Data System (ADS)

A spatial soliton is a shape invariant self guided beam of light or a self induced waveguide. Spatial solitons appear as a result of the balance of diffraction and nonlinear focusing in a system. They have been observed in many different conservative media in the last couple of years. Solitons are ubiquitous, because of the probability of using their interactions in optical data processing, communications etc. Up to now due to the power required to generate the solitons, and the response times of the soliton supporting media, these special waves of nature could not penetrate the applications arena. Semiconductors, with their resonant nonlinearities, are thought to be ideal candidates for fast switching, low power spatial solitons. In this dissertation it is shown theoretically and experimentally that it is possible to observe stable spatial solitons in a periodically patterned semiconductor optical amplifier (PPSOA). The solitons have unique beam profiles that change only with system parameters, like pumping current, etc. Their coherent and incoherent interactions which could lead to all optical devices have been investigated experimentally and theoretically. The formation of filaments or modulational instability has been studied theoretically and yielded analytical formulae for evaluating the filament gain and the maximum spatial frequencies in PPSOA devices. Furthermore, discrete array amplifiers have been analyzed numerically for discrete solitons, and the prospect of using multi peak discrete solitons as laser amplifiers is discussed.

Ultanir, Erdem

2004-11-01

362

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

363

Charge Pump Circuits: An Overview on Design Strategies and Topologies  

Microsoft Academic Search

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

Gaetano Palumbo; Domenico Pappalardo

2010-01-01

364

Critical charge concepts for CMOS SRAMs  

Microsoft Academic Search

The dramatic effects of external circuit loading on the heavy-ion-induced charge-collection response of a struck transistor are illustrated using three-dimensional mixed-mode simulations. Simulated charge-collection and SEU characteristics of a CMOS SRAM cell indicate that, in some cases, more charge call be collected at sensitive nodes from strikes that do not cause upset than from strikes that do cause upset. Computations

P. E. Dodd; F. W. Sexton

1995-01-01

365

Charged Membranes  

NSDL National Science Digital Library

This Teaching Resource provides three animated lessons that describe the storage and utilization of energy across plasma membranes. The “Na,K ATPase” animation explains how these pumps establish the electrochemical gradient that stores energy across plasma membranes. The “ATP synthesizing complexes” animation shows how these complexes transfer energy from the inner mitochondrial membrane to adenosine triphosphate (ATP). The “action potential” lesson explains how charged membranes are used to propagate signals along the axons of neurons. These animations serve as valuable resources for any collegiate-level course that describes these important factors. Courses that might employ them include introductory biology, biochemistry, biophysics, cell biology, pharmacology, and physiology.

Jack D. Thatcher (Lewisburg;West Virginia School of Osteopathic Medicine REV)

2013-04-16

366

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

367

CHARGE Association  

PubMed Central

We present here a case of 17-year-old boy from Kolkata presenting with obesity, bilateral gynecomastia, mental retardation, and hypogonadotrophic hypogonadism. The patient weighed 70 kg and was of 153 cm height. Facial asymmetry (unilateral facial palsy), gynecomastia, decreased pubic and axillary hair, small penis, decreased right testicular volume, non-palpable left testis, and right-sided congenital inguinal hernia was present. The patient also had disc coloboma, convergent squint, microcornea, microphthalmia, pseudohypertelorism, low set ears, short neck, and choanalatresia. He had h/o VSD repaired with patch. Laboratory examination revealed haemoglobin 9.9 mg/dl, urea 24 mg/dl, creatinine 0.68 mg/dl. IGF1 77.80 ng/ml (decreased for age), GH <0.05 ng/ml, testosterone 0.25 ng/ml, FSH-0.95 ?IU/ml, LH 0.60 ?IU/ml. ACTH, 8:00 A.M cortisol, FT3, FT4, TSH, estradiol, DHEA-S, lipid profile, and LFT was within normal limits. Prolactin was elevated at 38.50 ng/ml. The patient's karyotype was 46XY. Echocardiography revealed ventricularseptal defect closed with patch, grade 1 aortic regurgitation, and ejection fraction 67%. Ultrasound testis showed small right testis within scrotal sac and undescended left testis within left inguinal canal. CT scan paranasal sinuses revealed choanalatresia and deviation of nasal septum to the right. Sonomammography revealed bilateral proliferation of fibroglandular elements predominantly in subareoalar region of breasts. MRI of brain and pituitary region revealed markedly atrophic pituitary gland parenchyma with preserved infundibulum and hypothalamus and widened suprasellar cistern. The CHARGE association is an increasingly recognized non-random pattern of congenital anomalies comprising of coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia, ear abnormalities, and/or deafness.[1] These anomalies have a higher probability of occurring together. In this report, we have described a boy with CHARGE association. PMID:23565479

Chakraborty, Semanti; Chakraborty, Jayanta

2012-01-01

368

Gold nanoparticles conjugates-amplified aptamer immunosensing screen-printed carbon electrode strips for thrombin detection.  

PubMed

Thrombin plays the role in cardiovascular diseases and regulates many processes in inflammation and could be a feature of many pathological conditions, including the thromboembolic disease, cancer and neurodegenerative diseases. An ultrasensitive and amplified electrochemical sandwich assay using screen-printed carbon electrode (SPCE) strips for thrombin detection was established in this study. The conductivity and sensing performance of the carbon electrodes were enhanced by using gold nanoparticles (AuNPs). The aptamer addressed on the strips was used as a primary probe to capture thrombin in the detected samples. An amplifier was invented for recognizing thrombin captured on the SPCE, which is the multiple molecules of anti-thrombin antibody (Ab) and horseradish peroxidase (HRP) co-modified AuNPs (AuNPs/Ab-HRP). Hydrogen peroxide was used as the substrate for HRP and then the response current (RC) could be detected. The optimization of these AuNPs conjugates-amplified aptamer immunosensing SPCE strips was conducted for thrombin detection. The detection sensitivity showed a linear relation between RC and thrombin concentration in the range of 10 pM-100 nM, and limit of detection (LOD) was 1.5 pM. The fabricated AuNPs/Ab-HRP-amplified aptamer immunosensing SPCE strips were further used to detect thrombin in human serum with a linear range of 100 pM-100 nM. This study provided the promising SPCE strips with highly sensitive and rapid detection for thrombin by the electrochemical aptasensor combined with AuNPs conjugates for amplifying the detection signal. PMID:24912033

Yeh, Fang-Yuan; Liu, Ting-Yu; Tseng, I-Hua; Yang, Chung-Wei; Lu, Li-Che; Lin, Chih-Sheng

2014-11-15

369

47 CFR 15.204 - External radio frequency power amplifiers and antenna modifications.  

Code of Federal Regulations, 2012 CFR

...false External radio frequency power amplifiers and antenna modifications. 15.204...204 External radio frequency power amplifiers and antenna modifications. ...any external radio frequency power amplifier or amplifier kit intended for use...

2012-10-01

370

Stability of charged black holes in string theory under charged massive scalar perturbations  

NASA Astrophysics Data System (ADS)

Similar to the superradiant effect in Reissner-Nordström black holes, a charged scalar field can be amplified when impinging on the charged black hole in string theory. According to the black-hole bomb mechanism, the mass term of the incident field can work as the reflecting mirror, which may trigger the instability of the black hole. We study the possible instability triggered by superradiant effects and demonstrate that the charged black hole in string theory is stable against the massive charged scalar perturbation. The reason is that there is no trapping potential well in the black hole exterior, which is separated from the horizon by a potential barrier, and there are no bound states in the superradiant regime.

Li, Ran

2013-12-01

371

6-k, 43-Gb/s Differential Transimpedance-Limiting Amplifier with Auto-Zero Feedback and High Dynamic Range  

E-print Network

-Limiting- Amplifier (TIALA) with 100-µApp sensitivity and 4.5-mApp input overload current is presented. The circuit the transimpedance and limiting gain functions, an auto-zero DC feedback circuit, signal level monitor and slicing topology and on-chip isolation techniques. CIRCUIT DESIGN ISSUES The block diagram, shown in Fig.1

Voinigescu, Sorin Petre

372

Evaluation of a Modified Gen-Probe Amplified Direct Test for Detection of Mycobacterium tuberculosis Complex Organisms in Cerebrospinal Fluid  

Microsoft Academic Search

Laboratory evidence for tuberculous meningitis is difficult to acquire due to the low numbers of organisms present in cerebrospinal fluid (CSF) and the presence of nucleic acid amplification inhibitors. The Amplified Mycobacterium tuberculosis Direct Test (MTD) is sensitive and specific for the direct detection of M. tuberculosis complex in respiratory samples but has not been approved for CSF. We evaluated

Joann L. Cloud; Cheryl Shutt; Wade Aldous; Gail Woods

2004-01-01

373

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

PubMed Central

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

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

2008-01-01

374

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

SciTech Connect

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

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

2005-01-01

375

Development of 3 kW at 325 MHz solid-state RF power amplifier using four power amplifier modules  

NASA Astrophysics Data System (ADS)

A high power solid-state RF power amplifier of 3 kW at 325 MHz has been developed using only four RF power amplifier modules of 850 W power output each. The design and characterization of RF power modules have been presented. A four way Wilkinson power combiner adds the output of four power amplifier modules with a total transmission loss of less than 6%. The combined power amplifier has a power gain of 20.2 dB at 1-dB compression point, and the corresponding output power is 2.8 kW at 325 MHz. The drain efficiency of the power amplifier is 65.3% at 3 kW. All the harmonics of this amplifier are below -40 dBc. The amplifier has better characteristics like fewer numbers of active devices per kilo watt, high efficiency, high gain, and ruggedness etc for RF accelerator applications.

Ramarao, B. V.; Sonal, S.; Mishra, J. K.; Pande, M.; Singh, P.; Kumar, G.; Mukherjee, J.

2014-01-01

376

Double Helicity Asymmetry for Charged Pion + Jet Production in p+p Collisions at s =200 GeV at STAR  

NASA Astrophysics Data System (ADS)

Inclusive measurements from polarized proton-proton collisions at RHIC have constrained Deltag, the polarized gluon distribution function of the proton. Correlation observables, such as this pion+jet measurement, allow for reconstruction of initial parton kinematics and are thus sensitive to the x dependence of Deltag. By measuring charged pions opposite a jet, this particular measurement can be sensitive to the flavor of the struck parton. This measurement, which is dominated by the quark-gluon subprocess, can be divided into terms proportional to DeltauDelta g and DeltadDeltag. The relatively larger quark polarization amplifies the measured asymmetry thereby enhancing the statistical power. This thesis presents the result of the mid-rapidity pion+jet longitudinal double spin asymmetry analysis from 10.6 pb--1 of luminosity collected in the 2009 200 GeV p+p run. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

Hays-Wehle, James Prewitt

377

A analysis of the cathode coupled amplifier  

E-print Network

AN ANALySIS 0 TH CATHODE COOFL D ~iPLIPIER A Thesis by FORREST JACKS RETLING-. . R Approved as to style and content by: Chairman of Committee 'Head of Department August, 1951 AN ANALYSIS OF THE CATHODE COUPLED. AMPLIFIER by FORHEST JAMES.... The Cathode-Coupled Amplif 1er Circuit 2. The Cathode-Coupled Amplif ier Circuit shnwing a. c. components only 3. The Approximate A. C. Fquivalent, Circuit Page 17 4 ~ Aoproximate Equivalent C1rcu its f' or Calculating Output Impedances 22 5...

Hetlinger, Forrest James

2012-06-07

378

Chemically amplified photoresist: Materials and processes  

NASA Astrophysics Data System (ADS)

Advances in microfabrication technology to construct smaller and faster integrated circuits depend on improving resolution capabilities of patterning thin films of photoresist materials by photolithographic imaging. Positive-tone, chemically amplified photoresists represent one of the most important classes of photoresist materials. These materials function by the generation of a photoacid catalyst from the decomposition of a photoacid generator with exposure that catalyzes chemical reactions that alter the development rate of the exposed resist. Chemical amplification is derived from the fact that a single molecule of photogenerated catalyst may participate in numerous reactions. Photoacid catalyzes the cleavage of acid-labile protecting groups from the backbone of the resin polymer, increasing the dissolution rate of the resist in aqueous base. A pattern is formed in the photoresist film from the difference between dissolution rates of the exposed and unexposed material. The continual improvement of the resolution of chemically amplified resists depends on understanding, controlling, and optimizing the chemical processes that govern pattern formation, namely photoacid generation, resin deprotection, and resist dissolution. To elucidate how the formulation of the resist affects these processes, a systematic methodology was designed, validated and implemented to analyze the materials and processing of chemically amplified photoresist systems. The efficiency of photoacid generation and the concentration of photoacid produced upon exposure were determined for a wide range of resist formulations, processing conditions, and exposure technologies. The chemical structure of photoacid generators and base quenchers were found to affect the processes of acid-base neutralization, resin deprotection, and resist development. The reaction-diffusion process of photoacid to deprotect the resin was identified to depend on the concentration of the photoacid generator. A much greater concentration of photoacid was required to render development for ultra-thin films of chemically amplified photoresist less than 150nm thick than for thicker resist films. These investigations identified that the action of photoacid within the resist film is more complex than previously thought, and provided insight for the design and optimization of photoresist materials and processes.

Pawloski, Adam Richard

2002-01-01

379

Design of a High Performance Operational Amplifier  

NASA Astrophysics Data System (ADS)

The paper presents a design of low power operational amplifier for better frequency response using the nested Miller compensation scheme (NMCS). It shows better performance in terms of D.C. gain, slew rate, phase margin, settling time with drastic improvement in gain bandwidth product. The proposed circuit have full output swing and is better suited for low voltage, low power design. All simulations have been carried out on Tanner tool 0.35 ?m (TSMC) CMOS process with a supply voltage of 2v.

Bhardwaj, Monika; Singh, B. P.; Soni, Priyanka

2010-11-01

380

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 activated protein kinase pathways in the lapatinib-treated LR OE19 cells. Ectopic expression of Src E527K mutation also was sufficient to induce lapatinib resistance in drug-naïve cells. These results indicate that pathologic activation of Src is a potential mechanism of acquired resistance to ERBB2 inhibition in ERBB2-amplified gastroesophageal cancer. Although Src mutation has not been described in primary tumor samples, we propose that the Src hyperactivation should be investigated in the settings of acquired resistance to ERBB2 inhibition in esophageal and gastric adenocarcinoma. PMID:25350844

Hong, Yong Sang; Kim, Jihun; Pectasides, Eirini; Fox, Cameron; Hong, Seung-Woo; Ma, Qiuping; Wong, Gabrielle S.; Peng, Shouyong; Stachler, Matthew D.; Thorner, Aaron R.; Van Hummelen, Paul; Bass, Adam J.

2014-01-01

381

The cochlear amplifier: augmentation of the traveling wave within the inner ear  

PubMed Central

Purpose of review There have been many recent advancements in our understanding of cochlear function within the past ten years. In particular, several mechanisms that underlie the sensitivity and sharpness of mammalian tuning have been discovered. This review focuses on these issues. Recent findings The cochlear amplifier is essentially a positive feedback loop within the cochlea that amplifies the traveling wave. Thus, vibrations within the organ of Corti are sensed and then force is generated in synchrony to increase the vibrations. Mechanisms that generate force within the cochlea include outer hair cell electromotility and stereociliary active bundle movements. These processes can be modulated by the intracellular ionic composition, the lipid constituents of the outer hair cell plasma membrane, and the structure of the outer hair cell cytoskeleton. Summary A thorough understanding of the cochlear amplifier has tremendous implications to improve human hearing. Sensorineural hearing loss is a common clinical problem and a common site of initial pathology is the outer hair cell. Loss of outer hair cells causes loss of the cochlear amplifier, resulting in progressive sensorineural hearing loss. PMID:15377957

Oghalai, John S.

2005-01-01

382

Amplified and multiplexed detection of DNA using the dendritic rolling circle amplified synthesis of DNAzyme reporter units.  

PubMed

The amplified, highly sensitive detection of DNA using the dendritic rolling circle amplification (RCA) is introduced. The analytical platform includes a circular DNA and a structurally tailored hairpin structure. The circular nucleic acid template includes a recognition sequence for the analyte DNA (the Tay-Sachs mutant gene), a complementary sequence to the Mg(2+)-dependent DNAzyme, and a sequence identical to the loop region of the coadded hairpin structure. The functional hairpin in the system consists of the analyte-sequence that is caged in the stem region and a single-stranded loop domain that communicates with the RCA product. The analyte activates the RCA process, leading to DNA chains consisting of the Mg(2+)-dependent DNAzyme and sequences that are complementary to the loop of the functional hairpin structure. Opening of the coadded hairpin releases the caged analyte sequence, resulting in the dendritic RCA-induced synthesis of the Mg(2+)-dependent DNAzyme units. The DNAzyme-catalyzed cleavage of a fluorophore/quencher-modified substrate leads to a fluorescence readout signal. The method enabled the analysis of the target DNA with a detection limit corresponding to 1 aM. By the design of two different circular DNAs that include recognition sites for two different target genes, complementary sequences for two different Mg(2+)-dependent DNAzyme sequences and two different functional hairpin structures, the dendritic RCA-stimulated multiplexed analysis of two different genes is demonstrated. The amplified dendritic RCA detection of DNA is further implemented to yield the hemin/G-quadruplex horseradish peroxidase (HRP)-mimicking DNAzyme as catalytic labels that provide colorimetric or chemiluminescent readout signals. PMID:24377284

Wang, Fuan; Lu, Chun-Hua; Liu, Xiaoqing; Freage, Lina; Willner, Itamar

2014-02-01

383

Direct solar-pumped iodine laser amplifier  

NASA Technical Reports Server (NTRS)

The optimum conditions of a solar pumped iodine laser are found in this research for the case of a continuous wave operation and a pulsed operation. The optimum product of the pressure(p) inside the laser tube and the tube diameter(d) was pd=40 approx. 50 torr-cm on the contrary to the case of a high intensity flashlamp pumped iodine laser where the optimum value of the product is known to be pd=150 torr-cm. The pressure-diameter product is less than 1/3 of that of the high power iodine laser. During the research period, various laser materials were also studied for solar pumping. Among the laser materials, Nd:YAG is found to have the lowest laser threshold pumping intensity of about 200 solar constant. The Rhodamine 6G was also tested as the solar pumped laser material. The threshold pumping power was measured to be about 20,000 solar constant. The amplification experiment for a continuously pumped iodine laser amplifier was performed using Vortek solar simulator and the amplification factors were measured for single pass amplification and triple pass amplification of the 15 cm long amplifier tube. The amplification of 5 was obtained for the triple pass amplification.

Han, Kwang S.; Hwang, In Heon

1990-01-01

384

Hot prospect for new gene amplifier  

SciTech Connect

Molecular biologist Francis Barany is investigating one of the hottest areas in biotechnology: a gene-amplification technique called ligase chain reaction, or LCR. Already scientists have used LCR to detect the tiny mutation that causes sickle cell anemia and have adapted it to screen for a handful of other genetic diseases simultaneously - in a single test-tube. Some experts, in fact, are predicting that LCR will supplement the polymerase chain reaction (PCR), and in some cases even supplant it. LCR could revolutionize DNA diagnostics just as PCR transformed basic molecular biology following its introduction 6 years ago. With its ease of automation and ability to produce useful quantitative results, LCR could become a major player in the rapidly growing market for DNA diagnostics. LCR, like PCR, uses snippets of nucleic acid, or oligonucleotides, that anneal to a specific, complementary sequence on the target DNA to be amplified. But where PCR uses oligos that bracket the stretch to be amplified, LCR uses pairs of oligos that completely cover the target sequence.

Not Available

1991-11-29

385

Mechanical Amplifier for a Piezoelectric Transducer  

NASA Technical Reports Server (NTRS)

A mechanical amplifier has been devised to multiply the stroke of a piezoelectric transducer (PZT) intended for use at liquid helium temperatures. Interferometry holds the key to high angular resolution imaging and astrometry in space. Future space missions that will detect planets around other solar systems and perform detailed studies of the evolution of stars and galaxies will use new interferometers that observe at mid- and far-infrared wavelengths. Phase-measurement interferometry is key to many aspects of astronomical interferometry, and PZTs are ideal modulators for most methods of phase measurement, but primarily at visible wavelengths. At far infrared wavelengths of 150 to 300 m, background noise is a severe problem and all optics must be cooled to about 4 K. Under these conditions, piezos are ill-suited as modulators, because their throw is reduced by as much as a factor of 2, and even a wavelength or two of modulation is beyond their capability. The largest commercially available piezo stacks are about 5 in. (12.7 cm) long and have a throw of about 180 m at room temperature and only 90 m at 4 K. It would seem difficult or impossible to use PZTs for phase measurements in the far infrared were it not for the new mechanical amplifier that was designed and built.

Moore, James; Swain, Mark; Lawson, Peter; Calvet, Robert

2003-01-01

386

Ultrastable low-noise current amplifier  

E-print Network

An ultrastable low-noise current amplifier (ULCA) is presented. The ULCA is a non-cryogenic instrument based on specially designed operational amplifiers and resistor networks. It involves two stages, the first providing a 1000-fold current gain and the second performing a current-to-voltage conversion via an internal 1 MOhm reference resistor or, optionally, an external standard resistor. The ULCA's transfer coefficient is extremely stable versus time, temperature and current amplitude within the full dynamic range of +/-5 nA. A low noise level of 2.4 fA/sqrt(Hz) helps to keep averaging times low at small input currents. A cryogenic current comparator is used to calibrate both input current gain and output transresistance, providing traceability to the quantum Hall effect. Typically, within one day after calibration, the uncertainty contribution from short-term fluctuations of the transresistance is below one part in 10^7. The long-term stability is expected to be better than one part in 10^5 over a year. A ...

Drung, Dietmar; Becker, Ulrich; Scherer, Hansjörg; Ahlers, Franz Josef

2014-01-01

387

Advanced Interaction Studies of Travelling Wave Amplifiers  

NASA Astrophysics Data System (ADS)

The gain and electron beam-microwave interaction for a periodic rectangular grating slow wave Travelling Wave Tube (TWT) amplifier(J.Joe, L.Louis, J.Scharer, J.Booske, M. Basten, Phys. Plasmas, 1997 (Accepted for Publication).) and initial studies of multitone interaction in a helix TWT are presented. This research focusses on the low-voltage (<=10 kV) interaction in the backward wave regime for Ku-band range of frequencies. The grating has a shallow groove depth to period ratio of 0.446 to reduce skin effect losses. Simultaneous beam velocity spread and gain measurements are carried out in the new facility. Single and multiple pass gain measurements are presented and compared with theoretical predictions. Initial studies of the nonlinear physics of multitone interaction for an ultra-wide-band helix TWTA is studied. The characteristics of the harmonic and intermodulation products are examined. Preliminary results of analyses and realization of an experimental facility for examining the multitone amplifier helix TWTA interaction are presented.

Louis, L. J.; Scharer, J. E.; Booske, J. H.; Armstrong, C.

1997-11-01

388

QUANTUM ACTIVATION IN THE JOSEPHSON BIFURCATION AMPLIFIER  

E-print Network

SENSITIVITY & SPEED 01 Q sets sensitivity 01 what sets sensitivity ? #12;RF BIASED JUNCTION: PHASE DIAGRAM ??? VDC(nV) 1/Q Q=pRC sin( )RFi t sin( )RFi t + P ~ 0.1 fW #12;RF PHASE DIAGRAM: 4.7 GHz #12;START! * 5 15 7.2 p T mK k = = - h #12;> 20 FILTERS, 4 CIRCULATORS, SC SHIELD, etc... #12;RF SWITCHING IRF

Fominov, Yakov

389

Observation of self-amplifying Hawking radiation in an analog black hole laser  

E-print Network

It has been proposed that a black hole horizon should generate Hawking radiation. In order to test this theory, we have created a narrow, low density, very low temperature atomic Bose-Einstein condensate, containing an analog black hole horizon and an inner horizon, as in a charged black hole. We observe Hawking radiation emitted by the black hole. This is the output of the black hole laser. We also observe the exponential growth of a standing wave between the horizons. The latter results from interference between the negative energy partners of the Hawking radiation and the negative energy particles reflected from the inner horizon. We thus observe self-amplifying Hawking radiation.

Jeff Steinhauer

2014-09-23

390

Observation of self-amplifying Hawking radiation in an analog black hole laser  

E-print Network

It has been proposed that a black hole horizon should generate Hawking radiation. In order to test this theory, we have created a narrow, low density, very low temperature atomic Bose-Einstein condensate, containing an analog black hole horizon and an inner horizon, as in a charged black hole. We observe Hawking radiation emitted by the black hole. This is the output of the black hole laser. We also observe the exponential growth of a standing wave between the horizons. The latter results from interference between the negative energy partners of the Hawking radiation and the negative energy particles reflected from the inner horizon. We thus observe self-amplifying Hawking radiation.

Steinhauer, Jeff

2014-01-01

391

A CMOS In-Pixel CTIA High Sensitivity Fluorescence Imager  

PubMed Central

Traditionally, charge coupled device (CCD) based image sensors have held sway over the field of biomedical imaging. Complementary metal oxide semiconductor (CMOS) based imagers so far lack sensitivity leading to poor low-light imaging. Certain applications including our work on animal-mountable systems for imaging in awake and unrestrained rodents require the high sensitivity and image quality of CCDs and the low power consumption, flexibility and compactness of CMOS imagers. We present a 132×124 high sensitivity imager array with a 20.1 ?m pixel pitch fabricated in a standard 0.5 ? CMOS process. The chip incorporates n-well/p-sub photodiodes, capacitive transimpedance amplifier (CTIA) based in-pixel amplification, pixel scanners and delta differencing circuits. The 5-transistor all-nMOS pixel interfaces with peripheral pMOS transistors for column-parallel CTIA. At 70 fps, the array has a minimum detectable signal of 4 nW/cm2 at a wavelength of 450 nm while consuming 718 ?A from a 3.3 V supply. Peak signal to noise ratio (SNR) was 44 dB at an incident intensity of 1 ?W/cm2. Implementing 4×4 binning allowed the frame rate to be increased to 675 fps. Alternately, sensitivity could be increased to detect about 0.8 nW/cm2 while maintaining 70 fps. The chip was used to image single cell fluorescence at 28 fps with an average SNR of 32 dB. For comparison, a cooled CCD camera imaged the same cell at 20 fps with an average SNR of 33.2 dB under the same illumination while consuming over a watt. PMID:23136624

Murari, Kartikeya; Etienne-Cummings, Ralph; Thakor, Nitish; Cauwenberghs, Gert

2012-01-01

392

Intermodulation characteristics of X-band IMPATT amplifiers.  

NASA Technical Reports Server (NTRS)

Measurement of the intermodulation products produced when two equal amplitude signals are applied to the input of an X-band IMPATT diode amplifier. A Si p(+)nn(+) IMPATT diode was operated in a double-slug-tuned reflection amplifier circuit that was tuned to provide 20 dB of small-signal gain at 9.340 GHz. The intermodulation tests consist of measurements of the magnitudes and frequencies of the amplifier output signals as a function of the input signal drive levels and frequency separations. The gain and single-frequency characteristics of the amplifier were also measured and are used along with the theoretical device and circuit admittance characteristics as a basis for explanation of the intermodulation results. A low-frequency dominance mechanism is found to exist in which the low-frequency signals are amplified more than the high-frequency signals. This mechanism becomes more significant as the amplifier drive level is increased.

Trew, R. J.; Masnari, N. A.; Haddad, G. I.

1972-01-01

393

Combination ring cavity and backward Raman waveguide amplifier  

DOEpatents

A combination regenerative ring and backward Raman waveguide amplifier and a combination regenerative ring oscillator and backward Raman waveguide amplifier which produce Raman amplification, pulse compression, and efficient energy extraction from the CO.sub.2 laser pump signal for conversion into a Stokes radiation signal. The ring cavity configuration allows the CO.sub.2 laser pump signal and Stokes signal to copropagate through the Raman waveguide amplifier. The backward Raman waveguide amplifier configuration extracts a major portion of the remaining energy from the CO.sub.2 laser pump signal for conversion to Stokes radiation. Additionally, the backward Raman amplifier configuration produces a Stokes radiation signal which has a high intensity and a short duration. Adjustment of the position of overlap of the Stokes signal and the CO.sub.2 laser pump signal in the backward Raman waveguide amplifiers alters the amount of pulse compression which can be achieved.

Kurnit, Norman A. (Santa Fe, NM)

1983-01-01

394

Characteristics of Raman amplifiers in fiber optic communication systems  

NASA Astrophysics Data System (ADS)

Recently Raman amplifiers have started to attract much attention because the noise figure is smaller and it is less expensive than the EDFA. This paper simulated the characteristics of Raman amplifier by solving the coupled Raman amplifiers equations using the Runge Kutta method. The result of these simulation will be analyzed in terms of gain characteristics. The changing of the input pump power, the input signal power, and the length of Raman fiber amplifier are observed to have high influence to the gain amplifier. This paper also analyzed the noise figure as a result of light scattering in Raman amplifier. The resulting analysis are recommendations for maximum amplifications. In terms of fiber length, maximum gain, effective pump power, and noise figure.

Istianing, Dian Kusuma; Heryana, Amri; Syahriar, Ary

2012-06-01

395

First Observation of Self-Amplified Spontaneous Emission in a Free-Electron Laser at 109 nm Wavelength  

Microsoft Academic Search

We present the first observation of self-amplified spontaneous emission (SASE) in a free-electron laser (FEL) in the vacuum ultraviolet regime at 109 nm wavelength (11 eV). The observed free-electron laser gain (approximately 3000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width, and intensity fluctuations, are all consistent with the present models for SASE FELs.

J. Andruszkow; B. Aune; V. Ayvazyan; N. Baboi; R. Bakker; V. Balakin; D. Barni; A. Bazhan; M. Bernard; A. Bosotti; J. C. Bourdon; W. Brefeld; R. Brinkmann; S. Buhler; J.-P. Carneiro; M. Castellano; P. Castro; L. Catani; S. Chel; Y. Cho; S. Choroba; E. R. Colby; W. Decking; P. den Hartog; M. Desmons; M. Dohlus; D. Edwards; H. T. Edwards; B. Faatz; J. Feldhaus; M. Ferrario; M. J. Fitch; K. Flöttmann; M. Fouaidy; A. Gamp; T. Garvey; C. Gerth; M. Geitz; E. Gluskin; V. Gretchko; U. Hahn; W. H. Hartung; D. Hubert; M. Hüning; R. Ischebek; M. Jablonka; J. M. Joly; M. Juillard; T. Junquera; P. Jurkiewicz; A. Kabel; J. Kahl; H. Kaiser; T. Kamps; V. V. Katelev; J. L. Kirchgessner; M. Körfer; L. Kravchuk; G. Kreps; J. Krzywinski; T. Lokajczyk; R. Lange; B. Leblond; M. Leenen; J. Lesrel; M. Liepe; A. Liero; T. Limberg; R. Lorenz; Lu Hui Hua; Lu Fu Hai; C. Magne; M. Maslov; G. Materlik; A. Matheisen; J. Menzel; P. Michelato; W.-D. Möller; A. Mosnier; U.-C. Müller; O. Napoly; A. Novokhatski; M. Omeich; H. S. Padamsee; C. Pagani; F. Peters; B. Petersen; P. Pierini; J. Pflüger; P. Piot; B. Phung Ngoc; L. Plucinski; D. Proch; K. Rehlich; S. Reiche; D. Reschke; I. Reyzl; J. Rosenzweig; J. Rossbach; S. Roth; E. L. Saldin; W. Sandner; Z. Sanok; H. Schlarb; G. Schmidt; P. Schmüser; J. R. Schneider; E. A. Schneidmiller; H.-J. Schreiber; S. Schreiber; P. Schütt; J. Sekutowicz; L. Serafini; D. Sertore; S. Setzer; S. Simrock; B. Sonntag; B. Sparr; F. Stephan; V. A. Sytchev; S. Tazzari; F. Tazzioli; M. Tigner; M. Timm; M. Tonutti; E. Trakhtenberg; R. Treusch; D. Trines; V. Verzilov; T. Vielitz; V. Vogel; G. V. Walter; R. Wanzenberg; T. Weiland; H. Weise; J. Weisend; M. Wendt; M. Werner; M. M. White; I. Will; S. Wolff; M. V. Yurkov; K. Zapfe; P. Zhogolev; F. Zhou

2000-01-01

396

Climate Response Times: Dependence on Climate Sensitivity and Ocean Mixing  

Microsoft Academic Search

The factors that determine climate response times were investigated with simple models and scaling statements. The response times are particularly sensitive to (i) the amount that the climate response is amplified by feedbacks and (ii) the representation of ocean mixing. If equilibrium climate sensitivity is 3 degrees C or greater for a doubling of the carbon dioxide concentration, then most

J. Hansen; G. Russell; A. Lacis; I. Fung; D. Rind; P. Stone

1985-01-01

397

Detection of amplified Wuchereria bancrofti DNA in mosquitoes with a nonradioactive probe.  

PubMed

A technique to identify Wuchereria bancrofti larvae in mosquito vectors with an enzyme-labeled DNA probe is described. To overcome the low sensitivity of nonradioactive detection methods, analyte DNA was amplified by polymerase chain reaction (PCR). Oligonucleotide primers were used to amplify W. bancrofti-specific DNA fragments of 380 and 650 bp, respectively. Parasite DNA in mosquito extracts was isolated free of inhibitors of the PCR by hybridization to a biotinylated DNA fragment (IWb 67), which hybridizes to DNA from most filarial species, followed by absorption of the resulting DNA hybrids onto avidin-coated acrylic beads. PCR-amplified DNA was detected with a biotin-labeled W. bancrofti-specific repeat DNA (IWb 35) coupled to avidin-alkaline phosphatase and the chemiluminescent substrate, AMPPD. The DNA equivalent of less than one larva can be detected by this method in mosquito extracts. The sensitivity of detection was comparable to that of radioactive probes and the assay is suitable for field application in endemic countries. PMID:1675761

Dissanayake, S; Min, X; Piessens, W F

1991-03-01

398

High power two-stage single frequency PM fiber amplifier  

Microsoft Academic Search

We demonstrate a two-stage single frequency polarization maintaining Yb-doped fiber Amplifier at 1064 nm. The gain is 7 dB and 17.6 dB for the first and the second fiber amplifier. The output power is 17.3 W with 62.8% slope efficiency for second fiber amplifier and the polarization extinction ratio is better than 24.3 dB.

Liu Chi; Qi Yunfeng; Zhou Jun; Du Songtao; He Bing; Dong Jingxing; Wei Shirong; Lou Qihong; Wang Zhijiang

2009-01-01

399

Semiclassical particle-like description of optical amplifier noise  

Microsoft Academic Search

A semiclassical model of optical amplifier noise in terms of photon-particle description and simple calculations is developed. The active-medium amplifier is modelled as a stochastic photon multiplier, whose statistical properties are derived from well-known results about branching processes. The effects on amplifier output noise caused by random amplification of input photons and by spontaneous emission are treated separately, and it

G. Giuliani

1999-01-01

400

Pump interactions in a 100-nm bandwidth Raman amplifier  

Microsoft Academic Search

A design for a 100-nm bandwidth Raman amplifier is presented. The amplifier is pumped with eight, 130-mW lasers with wavelengths ranging from 1416 to 1502 nm. The peak-to-peak gain ripple is 1.1 dB. A new model was developed for this design that includes pump-to-pump and signal-to-signal interactions in addition to double Rayleigh scattering and amplified spontaneous emission. An understanding of

Howard Kidorf; Karsten Rottwitt; Morten Nissov; Matthew Ma; Eric Rabarijaona

1999-01-01

401

Ring cavity for a Raman capillary waveguide amplifier  

DOEpatents

Disclosed is a regenerative ring amplifier and regenerative ring oscillator which function to feed back a portion of the Stokes signal to complete the ring cavity. The ring cavity configuration allows the CO[sub 2] laser pump signal and Stokes signal to copropagate through the Raman capillary waveguide amplifier. A Raman capillary waveguide amplifier is also provided in the return leg of the ring cavity to increase gain without increasing the round trip time. Additionally, the ring cavity can be designed such that the amplifier Stokes signal is synchronous with the mode-locked spikes of the incoming CO[sub 2] laser pump signal. 6 figs.

Kurnit, N.A.

1983-07-19

402

Ring cavity for a raman capillary waveguide amplifier  

DOEpatents

A regenerative ring amplifier and regenerative ring oscillator which function to feed back a portion of the Stokes signal to complete the ring cavity. The ring cavity configuration allows the CO.sub.2 laser pump signal and Stokes signal to copropagate through the Raman capillary waveguide amplifier. A Raman capillary waveguide amplifier is also provided in the return leg of the ring cavity to increase gain without increasing the round trip time. Additionally, the ring cavity can be designed such that the amplifier Stokes signal is synchronous with the mode-locked spikes of the incoming CO.sub.2 laser pump signal.

Kurnit, Norman A. (Santa Fe, NM)

1983-07-19

403

Ring cavity for a Raman capillary waveguide amplifier  

DOEpatents

A regenerative ring amplifier and regenerative ring oscillator are described which function to feed back a portion of the Stokes signal to complete the ring cavity. The ring cavity configuration allows the CO/sub 2/ laser pump signal and Stokes signal to copropagate through the Raman capillary waveguide amplifier. A Raman capillary waveguide amplifier is also provided in the return leg of the ring cavity to increase gain without increasing the round trip time. Additionally, the ring cavity can be designed such that the amplified Stokes signal is synchronous with the mode-locked spikes of the incoming CO/sub 2/ laser pump signal.

Kurnit, N.A.

1981-01-27

404

Critical charge concepts for CMOS SRAMs  

SciTech Connect

The dramatic effects of external circuit loading on the heavy-ion-induced charge-collection response of a struck transistor are illustrated using three-dimensional mixed-mode simulations. Simulated charge-collection and SEU characteristics of a CMOS SRAM cell indicate that, in some cases, more charge can be collected at sensitive nodes from strikes that do not cause upset than from strikes that do cause upset. Computations of critical charge must taken into account the time during which charge is collected, not simply the total amount of charge collected. Model predictions of the incident linear energy transfer required to cause upset agree well with measured data for CMOS SRAMs, without parameter adjustments. The results show the absolute necessity of treating circuit effects in any realistic device simulation of single-event upset (SEU) in SRAMs.

Dodd, P.E.; Sexton, F.W. [Sandia National Labs., Albuquerque, NM (United States)] [Sandia National Labs., Albuquerque, NM (United States)

1995-12-01

405

Push-pull switching power amplifier  

NASA Technical Reports Server (NTRS)

A true push-pull switching power amplifier is disclosed utilizing two dc-to-dc converters. Each converter is comprised of two inductances, one inductance in series with a DC source and the other inductor in series with the output load, and an electrical energy transferring device with storage capability, namely storage capacitance, with suitable switching means between the inductances to obtain DC level conversion, where the switching means allows bidirectional current (and power) flow, and the switching means of one dc-to-dc converter is driven by the complement of a square-wave switching signal for the other dc-to-dc converter for true push-pull operation. For reduction of current ripple, the inductances in each of the two converters may be coupled, and with proper design of the coupling, the ripple can be reduced to zero at either the input or the output, but preferably the output.

Cuk, Slobodan M. (Inventor)

1980-01-01

406

Ghost interference with an optical parametric amplifier  

SciTech Connect

The 'ghost' interference experiment is analyzed when the source of entangled photons is a multimode optical parametric amplifier (OPA) whose weak limit is the two-photon spontaneous parametric down-conversion beam. The visibility of the double-slit pattern is calculated, taking the finite coincidence time window of the photon counting detectors into account. It is found that the coincidence window and the bandwidth of light reaching the detectors play a crucial role in the loss of visibility on coincidence detection, not only in the ghost interference experiment but in all experiments involving coincidence detection. The differences between the loss of visibility with two-mode and multimode OPA sources are also discussed.

Thanvanthri, Sulakshana; Rubin, Morton H. [Department of Physics, University of Maryland, Baltimore County, Baltimore, Maryland 21250 (United States)

2004-12-01

407

Quantum repeaters based on heralded qubit amplifiers  

E-print Network

We present a quantum repeater scheme based on the recently proposed qubit amplifier [N. Gisin, S. Pironio and N. Sangouard, Phys. Rev. Lett. 105, 070501 (2010)]. It relies on a on-demand entangled-photon pair source which uses on-demand single-photon sources, linear optical elements and atomic ensembles. Interestingly, the imperfections affecting the states created from this source, caused e.g. by detectors with non-unit efficiencies, are systematically purified from an entanglement swapping operation based on a two-photon detection. This allows the distribution of entanglement over very long distances with a high fidelity, i.e. without vacuum components and multiphoton errors. Therefore, the resulting quantum repeater architecture does not necessitate final postselections and thus achieves high entanglement distribution rates. This also provides unique opportunities for device-independent quantum key distribution over long distances with linear optics and atomic ensembles.

Ji?í Miná?; Hugues de Riedmatten; Nicolas Sangouard

2011-11-22

408

All optical latches using semiconductor optical amplifiers  

NASA Astrophysics Data System (ADS)

Semiconductor optical amplifiers are important for wide range of applications in optical networks, optical tomography and optical logic systems. For many of these applications particularly for optical networks and optical logic, high speed performance of the SOA is important. All optical Boolean operations such as XOR, OR, AND and NOR has been demonstrated using SOA based Mach-Zhender interferometers (SOA-MZI). A rate equation model for SOA-MZI has been developed. The model has been used to analyze the Set-Reset (S-R) latch, the gated S-R latch and the D-Flip-Flop devices. The modeling results suggest that the Flip-Flop circuits should work at high speeds.

Dutta, N. K.; Jaques, J.; Kang, I.

2010-06-01

409

Rippled beam free electron laser amplifier  

DOEpatents

A free electron laser amplifier provides a scalloping annular electron beam that interacts with the axial electric field of a TM.sub.0n mode. A waveguide defines an axial centerline and, a solenoid arranged about the waveguide produces an axial constant magnetic field within the waveguide. An electron beam source outputs a annular electron beam that interacts with the axial magnetic field to have an equilibrium radius and a ripple radius component having a variable radius with a ripple period along the axial centerline. An rf source outputs an axial electric field that propagates within the waveguide coaxial with the electron beam and has a radial mode that interacts at the electron beam at the equilibrium radius component of the electron beam.

Carlsten, Bruce E. (Los Alamos, NM)

1999-01-01

410

Dispersion measurement of the semiconductor optical amplifiers  

NASA Astrophysics Data System (ADS)

The semiconductor optical amplifier (SOA) is a key device for all optical signal processing based on its nonlinearity, which depends on its group velocity dispersion (GVD). A simple scheme to measure the GVD of the SOA is proposed with some computations from the measured gain spectra based on the relationship between GVD and the optical gain from the Kramers-Kronig relation. The dispersion is relatively flat in the range of 1530 nm~1610 nm, and lightly depends on the input power and the injection current. The peak-gain wavelength and zero-dispersion wavelength red-shift with the input power increasing and blue-shift with the injection current increasing, and the zero-dispersion wavelength is greater than the peak-gain wavelength on the longer wavelength side.

Wang, Zhi; Lin, Qing; Jian, Yangtian; Liu, Lanlan; Wu, Chongqing

2014-07-01

411

Single-frequency master-oscillator photonic crystal fiber amplifier with 148 W output power  

NASA Astrophysics Data System (ADS)

We report on a high-power ytterbium doped photonic crystal fiber amplifier using a single-frequency Nd:YAG non-planar ring oscillator seed source. With a large-mode-area photonic crystal fiber, operation below the threshold of stimulated Brillouin scattering is demonstrated with up to 148 W of continuous-wave output power and a slope efficiency of 75%. At maximum output power the amplified spontaneous emission was suppressed by more than 40 dB and the polarization extinction ratio was better than 22 dB. In order to investigate the overlap of the photonic crystal fiber transverse-mode with a Gaussian fundamental mode, sensitive beam quality measurements with a Fabry-Perot ring-cavity are presented.

Hildebrandt, Matthias; Frede, Maik; Kwee, Patrick; Willke, Benno; Kracht, Dietmar

2006-11-01

412

High-gain weakly nonlinear flux-modulated Josephson parametric amplifier using a SQUID array  

NASA Astrophysics Data System (ADS)

We have developed and measured a high-gain quantum-limited microwave parametric amplifier based on a superconducting lumped LC resonator with the inductor L including an array of eight superconducting quantum interference devices (SQUIDs). This amplifier is parametrically pumped by modulating the flux threading the SQUIDs at twice the resonator frequency. Around 5 GHz, a maximum gain of 31 dB, a product amplitude gain × bandwidth above 60 MHz, and a 1 dB compression point of -123 dBm at 20 dB gain are obtained in the nondegenerate mode of operation. Phase-sensitive amplification-deamplification is also measured in the degenerate mode and yields a maximum gain of 37 dB. The compression point obtained is 18 dB above what would be obtained with a single SQUID of the same inductance, due to the smaller nonlinearity of the SQUID array.

Zhou, X.; Schmitt, V.; Bertet, P.; Vion, D.; Wustmann, W.; Shumeiko, V.; Esteve, D.

2014-06-01

413

Novel polymeric sulfonium photoacid generator and its application for chemically amplified photoresists  

NASA Astrophysics Data System (ADS)

Chemically amplified resists (CARs) which involved the photoacid generator (PAG) have been widely used because of the high sensitivity. The inherent incompatibility between the polymer matrix and small molecular PAGs leads to problems including PAG phase separation, non-uniform initial PAG and photoacid distribution, as well as acid migration during the post-exposure baking (PEB) processes. The polymeric PAGs based resist systems which incorporated the PAG units into the main chain showed improved lithographic performance, such as faster photospeed and higher stability, lower outgassing, and lower LER than corresponding blend resists. In this paper, a novel type of polymeric PAGs based on poly (4-hydroxylstyrene) (PHS) was discussed. Chemically amplified photorssists were formed by the polymeric PAG and other film forming material containing acid labile groups. The polymeric PAGs showed advantage over the common small molecular PAG and patterns with 180 nm resolution was obtained in the 248-nm lithography.

Liu, Juan; Qiao, Yu; Wang, Liyuan

2014-03-01

414

Evaluation of a highly sensitive amperometric biosensor with low cholinesterase charge immobilized on a chemically modified carbon paste electrode for trace determination of carbamates in fruit, vegetable and water samples  

Microsoft Academic Search

A highly sensitive amperometric biosensor for determination of carbamate pesticides directly in water, fruit and vegetable samples has been evaluated, electrochemically characterized and optimized. The biosensor strip was fabricated in screen printed technique on a ceramic support using silver-based paste for reference electrode, and platinum-based paste for working and auxiliary electrodes. The working electrode was modified by a layer of

G. S Nunes; D Barceló; B. S Grabaric; J. M D??az-Cruz; M. L Ribeiro

1999-01-01

415

Modeling of induction-linac based free-electron laser amplifiers  

SciTech Connect

We describe the modeling of an induction-linac based free-electron laser (IFEL) amplifier for producing multimegawatt levels of microwave power. We have used the Lawrence Livermore National Laboratory (LLNL) free-electron laser simulation code, FRED, and the simulation code for sideband calculations, GINGER for this study. For IFEL amplifiers in the frequency range of interest (200 to 600 GHz), we have devised a wiggler design strategy which incorporates a tapering algorithm that is suitable for free-electron laser (FEL) systems with moderate space-charge effects and that minimizes spontaneous noise growth at frequencies below the fundamental, while enhancing the growth of the signal at the fundamental. In addition, engineering design considerations of the waveguide wall loading and electron beam fill factor in the waveguide set limits on the waveguide dimensions, the wiggler magnet gap spacing, the wiggler period, and the minimum magnetic field strength in the tapered region of the wiggler. As an example, we shall describe an FEL amplifier designed to produce an average power of about 10 MW at a frequency of 280 GHz to be used for electron cyclotron resonance heating of tokamak fusion devices. 17 refs., 4 figs.

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

1988-12-01

416

Modeling Of Induction-Linac Based Free-Electron Laser Amplifiers  

NASA Astrophysics Data System (ADS)

We describe the modeling of an induction-linac based free-electron laser (IFEL) amplifier for producing multi-megawatt levels of microwave power. We have used the Lawrence Livermore National Laboratory (LLNL) free-electron laser simulation code, FRED, and the simulation code for sideband calculations, GINGER for this study. For IFEL amplifiers in the frequency range of interest (200 to 600 GHz), we have devised a wiggler design strategy which incorporates a tapering algorithm that is suitable for free-electron laser (FEL) systems with moderate space-charge effects and that minimizes spontaneous noise growth at frequencies below the fundamental, while enhancing the growth of the signal at the fundamental. In addition, engineering design considerations of the waveguide wall loading and electron beam fill factor in the waveguide set limits on the waveguide dimensions, the wiggler magnet gap spacing, the wiggler period, and the minimum magnetic field strength in the tapered region of the wiggler. As an example, we shall describe an FEL amplifier designed to produce an average power of about 10 MW at a frequency of 280 GHz to be used for electron cyclotron resonance heating of tokamak fusion devices.

Jong, Raynard A.; Fawley, William M.; Scharlemann, Ernst T.

1989-05-01

417

Synthesis and photophysical properties of ruthenium(II) charge transfer sensitizers containing 4,4?-dicarboxy-2,2?-biquinoline and 5,8-dicarboxy-6,7-dihydro-dibenzo[1,10]-phenanthroline  

Microsoft Academic Search

Ruthenium (II) complexes of the type cis-Ru(H2dcbiq)2X2 and cis-Ru(H2dcdhph)2X2, where H2dcbiq=4,4?-dicarboxy-2,2?-biquinoline, H2dcdhph=5,8-dicarboxy-6,7-dihydro-dibenzo[1,10]-phenanthroline, and X=Cl?, NCS? or CN?, have been synthesized and spectroscopically characterized. The resulting complexes show a broad and intense metal-to-ligand charge transfer (MLCT) band in the visible region with a peak between 580 and 700 nm and are emissive at room temperature. The ground-state first pKa value of

Ashraful Islam; Hideki Sugihara; Lok Pratap Singh; Kohjiro Hara; Ryuzi Katoh; Yoshinobu Nagawa; Masatoshi Yanagida; Yoshiaki Takahashi; Shigeo Murata; Hironori Arakawa

2001-01-01

418

A 10Gb/s transimpedance amplifier for hybrid integration of a Ge PIN waveguide photodiode  

NASA Astrophysics Data System (ADS)

The presented paper describes a 10 Gbps optical receiver. The transimpedance amplifier (TIA) is realized in standard 0.35 ?m SiGe BiCMOS technology. The main novelty of the presented design - investigated in the European Community project HELIOS - is the hybrid connection of the optical detector. The used Germanium photodetector will be directly mounted onto the receiver. A model of the relevant parasitics of the photodetector itself and the novel connection elements (micropads, metal vias and metal lines) is described. Based on this photodetector model an optical receiver circuit was optimized for maximum sensitivity at data rates in the range of 10 Gbps. The design combines a TIA and two limiting amplifier stages followed by a 50 ? CML-style logic-level output driver. To minimize power supply noise and substrate noise, a fully differential design is used. A dummy TIA provides a symmetrical input signal reference and a control loop is used to compensate the offset levels. The TIA is built around a common-emitter stage and features a feedback resistor of 4.2 ?. The total transimpedance of the complete receiver chain is in the range of 275 k?. The value of the active feedback resistor can be reduced via an external control voltage to adapt the design to different overall gain requirements. The two limiting amplifier stages are realized as differential amplifiers with voltage followers. The output buffer is implemented with cascode differential amplifiers. The output buffer is capable of driving a differential 50? output with a calculated output swing of 800mVp-p. Simulations show an overall bandwidth of 7.2 GHz. The lower cutoff frequency is below 60 kHz. The equivalent input noise current is 408 nA. With an estimated total photodiode responsivity of 0.5 A/W this allows a sensitivity of around - 23.1 dBm (BER = 10-9). The device operates from a single 3.3 V power supply and the TIAs and the limiting amplifier consume 32 mA.

Polzer, A.; Gaberl, W.; Swoboda, R.; Zimmermann, H.; Fedeli, J.-M.; Vivien, L.

2010-05-01

419

Single event mirroring and DRAM sense amplifier designs for improved single-event-upset performance  

SciTech Connect

This paper proposes and investigates schemes for hardening the conventional CMOS cross-coupled DRAM sense amplifier to single event upset (SEU). These schemes, adapted from existing SRAM hardening techniques, are intended to harden the dynamic random access memory to bitline-mode errors during the sensing period. Simulation results indicate that a 9k[Omega] L-resistor hardening scheme provides greater than 24-fold improvement in critical charge over a significant part of the sensing period. Also proposed is a novel single event (SE) mirroring concept for SEU hardening of DRAMs. this concept has been implemented for hardening the bitlines to hits on diffusion region connected to the lines during the highly susceptible high-impedance state of the bitlines. It is shown to result in over 26-fold improvement in the level of critical charge using a 2pF dynamic capacitive coupling.

Gulati, K.; Massengill, L.W.; Agrawal, G.R. (Vanderbilt Univ., Nashville, TN (United States). Dept. of Electrical and Computer Engineering)

1994-12-01

420

High-Resolution Displacement Sensor Using a SQUID Array Amplifier  

NASA Technical Reports Server (NTRS)

Improvement in the measurement of displacement has profound implications for both exploration technologies and fundamental physics. For planetary exploration, the new SQUID-based capacitive displacement sensor will enable a more sensitive gravity gradiometer for mapping the interior of planets and moons. A new concept of a superfluid clock to be reported by Penanen and Chui at this workshop is also based on a high-resolution displacement sensor. Examples of high-impact physics projects that can benefit from a better displacement sensor are: detection of gravitational waves, test of the equivalence principle, search for the postulated "axion" particle, and test of the inverse square law of gravity. We describe the concept of a new displacement sensor that makes use of a recent development in the Superconducting Quantum Interference Device (SQUID) technology. The SQUID array amplifier, invented by Welty and Martinis (IEEE Trans. Appl. Superconductivity 3, 2605, 1993), has about the same noise as a conventional SQUID; however, it can work at a much higher frequency of up to 5 MHz. We explain how the higher bandwidth can be translated into higher resolution using a bridge-balancing scheme that can simultaneously balance out both the carrier signal at the bridge output and the electrostatic force acting on the test mass.

Chui, Talso; Penanen, Konstantin; Barmatz, M.; Paik, Ho Jung

2004-01-01

421

An instrumentation amplifier based readout circuit for a dual element microbolometer infrared detector  

NASA Astrophysics Data System (ADS)

The infrared band is widely used in many applications to solve problems stretching over very diverse fields, ranging from medical applications like inflammation detection to military, security and safety applications employing thermal imaging in low light conditions. At the heart of these optoelectrical systems lies a sensor used to detect incident infrared radiation, and in the case of this work our focus is on uncooled microbolometers as thermal detectors. Microbolometer based thermal detectors are limited in sensitivity by various parameters, including the detector layout and design, operating temperature, air pressure and biasing that causes self heating. Traditional microbolometers use the entire membrane surface for a single detector material. This work presents the design of a readout circuit amplifier where a dual detector element microbolometer is used, rather than the traditional single element. The concept to be investigated is based on the principle that both elements will be stimulated with a similar incoming IR signal and experience the same resistive change, thus creating a common mode signal. However, such a common mode signal will be rejected by a differential amplifier, thus one element is placed within a negative resistance converter to create a differential mode signal that is twice the magnitude of the comparable single mode signal of traditional detector designs. An instrumentation amplifier is used for the final stage of the readout amplifier circuit, as it allows for very high common mode rejection with proper trimming of the Wheatstone bridge to compensate for manufacturing tolerance. It was found that by implementing the above, improved sensitivity can be achieved.

de Waal, D. J.; Schoeman, J.

2014-06-01

422

High power Er3+\\/Yb3+ co-doped fiber amplifier of fiber length optimization  

Microsoft Academic Search

Aim to investigate the 1555 nm high power fiber amplifier with different lengths of gain fiber, a two-stage hybrid fiber amplifier structure was employed. It comprises an erbium-doped fiber amplifier (EDFA) as a pre-amplifier and an erbium\\/ytterbium co-doped double-cladding fiber amplifier (EYCDFA) as a post-amplifier. EDFA can pre-amplify the input signal and provide the good noise figure. EYCDFA as the

Wang Ji; Li Nan

2010-01-01

423

Spatially-selective amplified spontaneous emission source derived from an ultrahigh gain solid-state amplifier.  

PubMed

An investigation is made into the performance of a high power solid-state amplified spontaneous emission (ASE) source with near-diffraction-limited beam quality. The radiation from this ASE source has high spatial quality and power, but unlike a laser it has a high misalignment tolerance and does not require a precisely aligned cavity. The source is based on a diode-pumped Nd:YVO4 laser crystal in a bounce amplifier geometry with a uniquely ultra-high gain (~104-105). Double-pass ASE radiation with high power levels (>6W) is achieved in a near-diffraction-limited spatial quality. We further demonstrate that the double-pass ASE source also displays high spatial selectivity and capability to compensate for a phase diffuser, inserted in the double-pass arm, with only a small degradation in beam quality and power. PMID:19516475

Smith, G; Damzen, M J

2006-04-17

424

Retarding potential and induction charge detectors in tandem for measuring the charge and mass of nanodroplets  

SciTech Connect

The determination of the mass of a nanoparticle via time-of-flight typically requires a direct measurement of its charge. This can be done with a differential retarding potential analyzer and an induction charge detector operating in tandem. The spectrometer described in this article selects a particle with a specified retarding potential from a beam and directs it to an induction charge detector where both its velocity and charge are measured. The retarding potential, velocity, and charge also yield the particle's mass. The particle is analyzed without the need to collect it, and therefore can be employed in a subsequent experiment. The high charge sensitivity of the induction charge detector and the capability for working at low retarding potentials make the characterization of electrosprayed nanodroplets possible for the first time.

Gamero-Castano, Manuel [Department of Mechanical and Aerospace Engineering, University of California, Irvine, California 92717 (United States)

2009-05-15

425

Experimental investigation of an optically amplified time-division-multiplexed polarization-insensitive fiber-optic michelson interferometric sensor system.  

PubMed

We experimentally investigate optically amplified time-division-multiplexed polarization-insensitive fiber-optic Michelson interferometric (PIFOMI) sensor systems, using an erbium-doped fiber amplifier (EDFA) and a phase-generated carrier (PGC) demodulation technique. The influence of the EDFA on the extinction ratio (ER) of the light pulse and on the minimum phase-detection sensitivity (MPDS) is examined. We find that the EDFA acting as a preamplifier has limited usefulness because the highly amplified spontaneous emission (ASE) noise generated by the EDFA degrades the ER and the MPDS. However, both postamplifiers and in-line EDFA's can work successfully. The MPDS of the unamplified time-division-multiplexed PIFOMI system with an ER of 33 dB was 2.4 x 10(-5) rad/(Hz)(1/2) at ~1 kHz. For maintaining a MPDS of better than 3.4 x 10(-5) rad/(Hz)(1/2) at ~1 kHz, the worst ER's for the postamplified and in-line amplified systems were 20 and 17.8 dB, respectively. The corresponding input signal peak power should be larger than -20 and -25 dBm for the postamplifiers and in-line amplifiers, respectively. When two postamplifiers and two in-line amplifiers are used, an allowable sensor system loss of 47 dB and a link length of the input-output lead fiber of 108 km can be realized for this system with a 32-sensor array. Implementation of optically amplified time-division-multiplexed and wavelength-division multiplexed-time-division multiplexed PIFOMI subarray sensor systems are also addressed. PMID:18301468

Chen, Y K; Law, P C; Huang, S C

1998-10-01

426

Tokamak Fusion Test Reactor charge exchange atom spectrometry using a natural diamond detector  

NASA Astrophysics Data System (ADS)

Natural diamond detectors (NDD) developed in Russia were used for fast charge exchange H0 atom spectrometry and flux dynamic measurements during Tokamak Fusion Test Reactor (TFTR) H+ minority ion cyclotron resonance heating (ICRH) experiments in deuterium plasma. For selected NDDs, the high energy resolution (˜2%-3%) and radiation resistance (5×1014n/cm2) and low sensitivity to neutrons and gammas enable spectrometry of fast (0.2-3 MeV) atoms in TFTR radiation conditions. The NDD compact housing (˜2 cm+3) allowed noninterfering insertion into the particle charge exchange flight tube giving both systems similar views which allows comparison of their spectra and fluxes. A small NDD was chosen to limit count rates to 7×105s-1. A spectroscopy amplifier operating with pileup inspection at such rates was developed, enabling measurement of the dependence of fast perpendicular proton energy spectra on ICRH heating power during sawtooth-free and sawtooth-crash times. The results agree with a model developed for sawtooth redistribution of fast particles.

Krasilnikov, A. V.; Medley, S. S.; Gorelenkov, N. N.; Budny, R. V.; Ignatyev, O. V.; Kaschuck, Yu A.; Petrov, M. P.; Roquemore, A. L.

1999-01-01

427

Reflection Amplifiers in Online Courses: A Classification Framework  

ERIC Educational Resources Information Center

This paper provides a theoretical framework for "reflection amplifiers" that are used in online courses. Such reflection amplifiers are intervention techniques that aim at provoking reflective practices in learning, in order to enhance the quality and effectiveness of learning and promote meta-cognition. A literature survey identified a sample of…

Verpoorten, Dominique; Westera, Wim; Specht, Marcus

2011-01-01

428

Efficient wide-aperture neodymium glass rod amplifiers  

SciTech Connect

Amplifiers based on neodymium phosphate glass rods 60 - 100 mm in diameter are experimentally studied. The amplifiers are pumped by INP-16/250 tubular flash lamps placed in a universal pump cavity with a two-section mirror reflector. A compact high-voltage capacitive energy storage with a preionisation circuit was developed to supply the lamps. (lasers)

Potemkin, A K; Zhurin, K A; Kirsanov, A V; Kopelovich, E A; Kuznetsov, M V; Kuz'min, A A; Flat, F A; Khazanov, Efim A; Shaikin, A A [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod (Russian Federation)

2011-06-30

429

Amplified spontaneous emission in solar-pumped iodine laser  

NASA Technical Reports Server (NTRS)

The amplified spontaneous emission (ASE) from a long pulse, solar-simulating radiation pumped iodine laser amplifier is studied. The ASE threshold pump intensity is almost proportional to the inverse of the laser gain length when the gas pressure is constant in the laser tube.

Cho, Yong S.; Hwang, In H.; Han, Kwang S.; Lee, Ja H.

1992-01-01

430

Conductively Cooled Ho:Tm:LuLiF Laser Amplifier  

NASA Technical Reports Server (NTRS)

A conductively-cooled Ho:Tm:LuLiF laser head can amplify 80mJ/340ns probe pulses into 400mJ when the pump pulse energy is close to amplified spontaneous emission (ASE) threshold, 5.6J. For a small signal, the double-pass amplification exceeds 25.

Bai, Yingxin; Yu, Jirong; Trieu, Bo; Petros, M.; Petzar, Paul; Lee, Hyung; Singh, U.

2008-01-01

431

An Information Theoretic Approach to Optimal Amplifier Operation  

E-print Network

An Information Theoretic Approach to Optimal Amplifier Operation Nicole M. Nelson and Pamela A by the presence of intrinsic physical noise sources. We analyze the information transfer rates for simple and wide-range operational transconductance amplifiers (OTAs) using the principles of information theory. Frequency transfer

Maryland at College Park, University of

432

Band-Pass Amplifier Without Discrete Reactance Elements  

NASA Technical Reports Server (NTRS)

Inherent or "natural" device capacitance exploited. Band-Pass Circuit has input impedance of equivalent circuit at frequencies much greater than operational-amplifier rolloff frequency. Apparent inductance and capacitance arise from combined effects of feedback and reactive component of amplifier gain in frequency range.

Kleinberg, L.

1984-01-01

433

External Peltier Cooler For Low-Noise Amplifier  

NASA Technical Reports Server (NTRS)

Inexpensive Peltier-effect cooling module made of few commercially available parts used to reduce thermal noise in microwave amplifier. Retrofitted to almost any microwave low-noise amplifier or receiver preamplifier used in communication, telemetry, or radar. Includes copper or aluminum cold plate held tightly against unit to be cooled by strap-type worm-gear clamps.

Soper, Terry A.

1990-01-01

434

Note: a transimpedance amplifier for remotely located quartz tuning forks.  

PubMed

The cable capacitance in cryogenic and high vacuum applications of quartz tuning forks imposes severe constraints on the bandwidth and noise performance of the measurement. We present a single stage low noise transimpedance amplifier with a bandwidth exceeding 1 MHz and provide an in-depth analysis of the dependence of the amplifier parameters on the cable capacitance. PMID:23278030

Kleinbaum, Ethan; Csáthy, Gábor A

2012-12-01

435

High efficiency frequency stabilized tapered amplifiers with improved brightness  

Microsoft Academic Search

Semiconductor laser diodes with a tapered gain region provide a beam quality near to the diffraction limit combined with high output power. They can be configured as laser with a high-reflectivity coating on the rear facet as well as amplifier with an antireflection coating on both facets. In amplifier configuration they can be used in external cavity or MOPA -

Patrick Friedmann; Jürgen Gilly; Jeanette Schleife; Catharina Giesin; Stefan Moritz; Marilena Herbstritt; Mathias Fatscher; Marc T. Kelemen

2011-01-01

436

Analysis and simulation of single-frequency Raman fiber amplifiers  

Microsoft Academic Search

High power operation of single-frequency Raman fiber amplifiers is usually limited by the onset of stimulated Brillouin scattering. A theoretical investigation on single-frequency Raman fiber amplifier limited by stimulated Brillouin scattering is presented in this paper, based on the intensity equations combining stimulated Brillouin scattering and stimulated Raman scattering. A combination of methods is proposed to increase the output power

Jinyong Leng; Shengping Chen; Wuming Wu; Jing Hou; Xiaojun Xu

2011-01-01

437

Tapered fiber amplifier with high gain and output power  

NASA Astrophysics Data System (ADS)

We present a high-power ytterbium fiber amplifier based on active tapered double-clad fiber (T-DCF) and capable of high single-pass gain. The T-DCF power amplifier seeded with a 320 mW narrow-band signal generates up to 110 W of average output power corresponding to more than 25 dB gain. The amplifier exhibits near-diffraction-limited beam quality ( M 2 = 1.06) at the highest output power, which was limited by the available pump power. With a broadband seed source, the amplifier produced a gain of nearly 40 dB obtained for low-signal limit of the seed. The high output power combined with high gain is achieved owing to amplified spontaneous emission (ASE) filtering and increased stimulated Brillouin scattering (SBS) threshold inherent to the axially non-uniform geometry. The amplifier operates efficiently with a wide range of input seed powers thus providing the basis for one-stage tapered amplifier which combines the functions of preamplifier and power amplifier and can be a competitive alternative to multi-stage design.

Kerttula, J.; Filippov, V.; Chamorovskii, Y.; Ustimchik, V.; Golant, K.; Okhotnikov, O. G.

2012-11-01

438

Experimental investigation of tapered erbium-doped fiber amplifiers  

Microsoft Academic Search

Low noise erbium-doped fiber amplifiers find widespread use in telecommunication systems. Different design ideas have been presented for such amplifiers, including various pump configurations, the use of filters, and advanced active fiber design. In this paper we present an experimental confirmation of a fiber design based on an Er\\/Al doped untapered fiber. As recently predicted theoretically, a continuous uptapering of

Anders Grunnet-Jepsen; Kim Schuesler; Svend Dahl-Petersen; Bera Palsdottir; Anders Bjarklev; Karsten Rottwitt; Jorn Hedegaard Povlsen; Thomas P. Rasmussen

1993-01-01

439

Distributed nonlinear fiber chirped-pulse amplifier system  

E-print Network

Distributed nonlinear fiber chirped-pulse amplifier system Marc Hanna,* Dimitris Papadopoulos-stage fiber-based femtosecond amplification system is presented, based on chirped-pulse amplification. 2009 Optical Society of America OCIS codes: (060.2320) Fiber optics amplifiers and oscillators; (140

Paris-Sud XI, Université de

440

Distortion analysis of Miller-compensated three-stage amplifiers  

Microsoft Academic Search

This paper proposes a theoretical approach for evaluating distortion in the frequency domain of three-stage amplifiers adopting two commonly used compensation techniques, namely the nested Miller (NM) and the reversed NM. The analysis is based on appropriate amplifier modeling and on the assumption that the nonlinearity generated by each stage is static. Calculations are thus greatly simplified avoiding complex methods

Salvatore Omar Cannizzaro; Gaetano Palumbo; Salvatore Pennisi

2006-01-01