Fast Pb-glass neutron-to-light converter for ICF (Inertial Confinement Fusion) target burn history measurements

NASA Astrophysics Data System (ADS)

Lerche, R. A.; Cable, M. D.; Phillion, D. W.

1990-09-01

We are developing a streak camera based instrument to diagnose the fusion reaction rate (burn history) within laser-driven ICF targets filled with D-T fuel. Recently, we attempted measurements using the 16.7 MeV gamma ray emitted in the T(d,gamma)He(5) fusion reaction. Pb glass which has a large cross section for pair production acts as a gamma-ray-to-light converter. Gamma rays interact within the glass to form electron-positron pairs that produce large amounts (1000 photons/gamma ray) of prompt (less than 10 ps) Cerenkov light as they slow down. In our experimental instrument, an f/10 Cassegrain telescope optically couples light produced within the converter to a streak camera having 20-ps resolution. Experiments using high-yield (10(exp 13) D-T neutrons), direct-drive targets at Nova produced good signals with widths of 200 ps. Time-of-flight measurements show the signals to be induced by neutrons rather than gamma rays. The Pb glass appears to act as a fast neutron-to-light converter. We continue to study the interactions process and the possibility of using the 16.7 MeV gamma rays for burn time measurements.

Sequence control of phase separation and dewetting in PS/PVME blend thin films by changing molecular weight of PS.

PubMed

Xia, Tian; Qin, Yaping; Huang, Yajiang; Huang, Ting; Xu, Jianhui; Li, Youbing

2016-11-28

The morphology evolution mechanism of polystyrene (PS)/poly (vinyl methyl ether) (PVME) blend thin films with different PS molecular weights (M w ) was studied. It was found that the morphology evolution was closely related to the molecular weight asymmetry between PS and PVME. In the film where M w (PS) ≈ M w (PVME), dewetting happened at the interface between the bottom layer and substrate after SD phase separation. While in the film where M w (PS) > M w (PVME), dewetting happened at the interface between the middle PS/PVME blend layer and bottom PVME layer near the substrate prior to phase separation. The different sequences of phase separation and dewetting and different interface for dewetting occurrence were studied by regarding the competitive effects of viscoelasticity contrast between polymer components and preferential wetting between PVME and the substrate. The viscoelastic nature of the PS component played a crucial role in the sequence of phase separation and dewetting.

Experimental demonstration of wavelength conversion between ps-pulses based on cascaded sum- and difference frequency generation (SFG+DFG) in LiNbO3 waveguides

NASA Astrophysics Data System (ADS)

Wang, Jian; Sun, Junqiang; Lou, Chuanhong; Sun, Qizhen

2005-09-01

All-optical wavelength conversion between ps-pulses based on cascaded sum- and difference frequency generation (SFG+DFG) is proposed and experimentally demonstrated in periodically poled LiNbO3 (PPLN) waveguides. The signal pulse with 40-GHz repetition rate and 1.57- ps pulse width is adopted. The converted idler wavelength can be tuned from 1527.4 to 1540.5nm as the signal wavelength is varied from 1561.9 to 1548.4nm. No obvious changes of the pulse shape and width, also no chirp are observed in the converted idler pulse. The results imply that single-to-multiple channel wavelength conversions can be achieved by appropriately tuning the two pump wavelengths.

Experimental demonstration of wavelength conversion between ps-pulses based on cascaded sum- and difference frequency generation (SFG+DFG) in LiNbO3 waveguides.

PubMed

Wang, Jian; Sun, Junqiang; Lou, Chuanhong; Sun, Qizhen

2005-09-19

All-optical wavelength conversion between ps-pulses based on cascaded sum- and difference frequency generation (SFG+DFG) is proposed and experimentally demonstrated in periodically poled LiNbO3 (PPLN) waveguides. The signal pulse with 40-GHz repetition rate and 1.57- ps pulse width is adopted. The converted idler wavelength can be tuned from 1527.4 to 1540.5nm as the signal wavelength is varied from 1561.9 to 1548.4nm. No obvious changes of the pulse shape and width, also no chirp are observed in the converted idler pulse. The results imply that single-to-multiple channel wavelength conversions can be achieved by appropriately tuning the two pump wavelengths.

Multichannel low power time-to-digital converter card with 21 ps precision and full scale range up to 10 μs

NASA Astrophysics Data System (ADS)

Tamborini, D.; Portaluppi, D.; Villa, F.; Tisa, S.; Tosi, A.

2014-11-01

We present a Time-to-Digital Converter (TDC) card with a compact form factor, suitable for multichannel timing instruments or for integration into more complex systems. The TDC Card provides 10 ps timing resolution over the whole measurement range, which is selectable from 160 ns up to 10 μs, reaching 21 ps rms precision, 1.25% LSB rms differential nonlinearity, up to 3 Mconversion/s with 400 mW power consumption. The I/O edge card connector provides timing data readout through either a parallel bus or a 100 MHz serial interface and further measurement information like input signal rate and valid conversion rate (typically useful for time-correlated single-photon counting application) through an independent serial link.

Multichannel low power time-to-digital converter card with 21 ps precision and full scale range up to 10 μs.

PubMed

Tamborini, D; Portaluppi, D; Villa, F; Tisa, S; Tosi, A

2014-11-01

We present a Time-to-Digital Converter (TDC) card with a compact form factor, suitable for multichannel timing instruments or for integration into more complex systems. The TDC Card provides 10 ps timing resolution over the whole measurement range, which is selectable from 160 ns up to 10 μs, reaching 21 ps rms precision, 1.25% LSB rms differential nonlinearity, up to 3 Mconversion/s with 400 mW power consumption. The I/O edge card connector provides timing data readout through either a parallel bus or a 100 MHz serial interface and further measurement information like input signal rate and valid conversion rate (typically useful for time-correlated single-photon counting application) through an independent serial link.

Silicon RFIC Techniques for Reconfigurable Military Applications

DTIC Science & Technology

2008-12-01

21 3.2.1 Motivation ...2008-295 21 3.2 Distributed Cascode LNAs at 20 GHz 3.2.1 Motivation Millimetrewave integrated circuits are traditionally implemented using...ZRef=50. Ohm Phase=-45. PhaseShiftSML PS4 ZRef=50. Ohm Phase=-22.5 PhaseShiftSML PS7 ZRef=50. Ohm Phase=-180 PhaseShiftSML PS8 ZRef=50. Ohm Phase=-180

Nanoporous Membranes with Chemically-Tailored Pore Walls from Triblock Terpolymer Templates

NASA Astrophysics Data System (ADS)

Mulvenna, Ryan; Weidman, Jacob; Pople, John; Boudouris, Bryan; Phillip, William

2014-03-01

Membranes generated from self-assembled block polymers have shown promise as highly permeable and selective filters; however, current syntheses of such materials lack diverse pore wall chemical functionality. Here, we report the facile synthesis of polyisoprene- b-polystyrene- b-poly(N , N -dimethylacrylamide) (PI-PS-PDMA) using a controlled reversible addition-fragmentation chain transfer (RAFT) polymerization mechanism to yield a macromolecule with an easily-tunable molecular weight and a narrow molecular weight distribution. The PI-PS-PDMA is then cast into an anisotropic membrane using the self-assembly and non-solvent induced phase separation process (SNIPS) protocol. These membranes can be used in size-selective separations for particles as small as 8 nm in diameter. Furthermore, the PDMA block can be converted to poly(acrylic acid) (PAA) readily in the solid state, and this PI-PS-PAA terpolymer membrane can separate particles as low as 2 nm in diameter while still retaining a relatively high flux. This is the smallest reported separation for a block polymer-based membrane to date. Additionally, the PAA-lined pores serve as a conversion platform to be tuned to any other pore chemistry, which allows the membrane to be of great utility in optimizing chemistry-specific separations.

Multichannel low power time-to-digital converter card with 21 ps precision and full scale range up to 10 μs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamborini, D., E-mail: davide.tamborini@polimi.it; Portaluppi, D.; Villa, F.

We present a Time-to-Digital Converter (TDC) card with a compact form factor, suitable for multichannel timing instruments or for integration into more complex systems. The TDC Card provides 10 ps timing resolution over the whole measurement range, which is selectable from 160 ns up to 10 μs, reaching 21 ps rms precision, 1.25% LSB rms differential nonlinearity, up to 3 Mconversion/s with 400 mW power consumption. The I/O edge card connector provides timing data readout through either a parallel bus or a 100 MHz serial interface and further measurement information like input signal rate and valid conversion rate (typically usefulmore » for time-correlated single-photon counting application) through an independent serial link.« less

Research and application of spectral inversion technique in frequency domain to improve resolution of converted PS-wave

NASA Astrophysics Data System (ADS)

Zhang, Hua; He, Zhen-Hua; Li, Ya-Lin; Li, Rui; He, Guamg-Ming; Li, Zhong

2017-06-01

Multi-wave exploration is an effective means for improving precision in the exploration and development of complex oil and gas reservoirs that are dense and have low permeability. However, converted wave data is characterized by a low signal-to-noise ratio and low resolution, because the conventional deconvolution technology is easily affected by the frequency range limits, and there is limited scope for improving its resolution. The spectral inversion techniques is used to identify λ/8 thin layers and its breakthrough regarding band range limits has greatly improved the seismic resolution. The difficulty associated with this technology is how to use the stable inversion algorithm to obtain a high-precision reflection coefficient, and then to use this reflection coefficient to reconstruct broadband data for processing. In this paper, we focus on how to improve the vertical resolution of the converted PS-wave for multi-wave data processing. Based on previous research, we propose a least squares inversion algorithm with a total variation constraint, in which we uses the total variance as a priori information to solve under-determined problems, thereby improving the accuracy and stability of the inversion. Here, we simulate the Gaussian fitting amplitude spectrum to obtain broadband wavelet data, which we then process to obtain a higher resolution converted wave. We successfully apply the proposed inversion technology in the processing of high-resolution data from the Penglai region to obtain higher resolution converted wave data, which we then verify in a theoretical test. Improving the resolution of converted PS-wave data will provide more accurate data for subsequent velocity inversion and the extraction of reservoir reflection information.

A flexible 32-channel time-to-digital converter implemented in a Xilinx Zynq-7000 field programmable gate array

NASA Astrophysics Data System (ADS)

Wang, Yonggang; Kuang, Jie; Liu, Chong; Cao, Qiang; Li, Deng

2017-03-01

A high performance multi-channel time-to-digital converter (TDC) is implemented in a Xilinx Zynq-7000 field programmable gate array (FPGA). It can be flexibly configured as either 32 TDC channels with 9.9 ps time-interval RMS precision, 16 TDC channels with 6.9 ps RMS precision, or 8 TDC channels with 5.8 ps RMS precision. All TDCs have a 380 M Samples/second measurement throughput and a 2.63 ns measurement dead time. The performance consistency and temperature dependence of TDC channels are also evaluated. Because Zynq-7000 FPGA family integrates a feature-rich dual-core ARM based processing system and 28 nm Xilinx programmable logic in a single device, the realization of high performance TDCs on it will make the platform more widely used in time-measuring related applications.

Retrieving Coherent Receiver Function Images with Dense Arrays

NASA Astrophysics Data System (ADS)

Zhong, M.; Zhan, Z.

2016-12-01

Receiver functions highlight converted phases (e.g., Ps, PpPs, sP) and have been widely used to study seismic interfaces. With a dense array, receiver functions (RFs) at multiple stations form a RF image that can provide more robust/detailed constraints. However, due to noise in data, non-uniqueness of deconvolution, and local structures that cannot be detected across neighboring stations, traditional RF images are often noisy and hard to interpret. Previous attempts to enhance coherence by stacking RFs from multiple events or post-filtering the RF images have not produced satisfactory improvements. Here, we propose a new method to retrieve coherent RF images with dense arrays. We take advantage of the waveform coherency at neighboring stations and invert for a small number of coherent arrivals for their RFs. The new RF images contain only the coherent arrivals required to fit data well. Synthetic tests and preliminary applications on real data demonstrate that the new RF images are easier to interpret and improve our ability to infer Earth structures using receiver functions.

Immobilization and functional reconstitution of antibody Fab fragment by solid-phase refolding.

PubMed

Kumada, Yoichi; Hamasaki, Kyoto; Nakagawa, Aya; Sasaki, Eiju; Shirai, Tatsunori; Okumura, Masahiro; Inoue, Manami; Kishimoto, Michimasa

2013-12-31

In this study, we demonstrated the successful preparation of a Fab antibody-immobilized hydrophilic polystyrene (phi-PS) plate via one- and two-step solid-phase refolding methods. Both polystyrene-binding peptide (PS-tag)-fused Fd fragment of heavy chain (Fab H-PS) and full-length of light-chain (Fab L-PS) were individually produced in insoluble fractions of Escherichia coli cells, and they were highly purified in the presence of 8M of urea. Antigen-binding activities of Fab antibody immobilized were correctly recovered by the one-step solid-phase refolding method that a mixture of Fab H-PS and Fab L-PS was immobilized in the presence of 0.5-2M urea, followed by surface washing of the phi-PS plate with PBST. These results indicate that by genetic fusion of a PS-tag, a complex between Fab H and Fab L was efficiently immobilized on the surface of a phi-PS plate even in the presence of a low concentration of urea, and was then correctly refolded to retain its high antigen-binding activity via removal of the urea. A two-step solid-phase refolding method whereby Fab H-PS and Fab L-PS were successively refolded on the surface of a phi-PS plate also resulted in Fab antibody formation on the plate. Furthermore, both the binding affinity and the specificity of the Fab antibody produced by the two-step method were highly maintained, according to the results of sandwich ELISA and competitive ELISA using Fab antibody-immobilized plate via two-step solid-phase refolding. Thus, the solid-phase refolding method demonstrated in this study should be quite useful for the preparation of a Fab antibody-immobilized PS surface with high efficiency from individually produced Fab H-PS and Fab L-PS. This method will be applicable to the preparation of a large Fab antibody library on the surface of a PS plate for use in antibody screening. © 2013. Published by Elsevier B.V. All rights reserved.

Picosecond Resolution Time-to-Digital Converter Using Gm-C Integrator and SAR-ADC

NASA Astrophysics Data System (ADS)

Xu, Zule; Miyahara, Masaya; Matsuzawa, Akira

2014-04-01

A picosecond resolution time-to-digital converter (TDC) is presented. The resolution of a conventional delay chain TDC is limited by the delay of a logic buffer. Various types of recent TDCs are successful in breaking this limitation, but they require a significant calibration effort to achieve picosecond resolution with a sufficient linear range. To address these issues, we propose a simple method to break the resolution limitation without any calibration: a Gm-C integrator followed by a successive approximation register analog-to-digital converter (SAR-ADC). This translates the time interval into charge, and then the charge is quantized. A prototype chip was fabricated in 90 nm CMOS. The measurement results reveal a 1 ps resolution, a -0.6/0.7 LSB differential nonlinearity (DNL), a -1.1/2.3 LSB integral nonlinearity (INL), and a 9-bit range. The measured 11.74 ps single-shot precision is caused by the noise of the integrator. We analyze the noise of the integrator and propose an improved front-end circuit to reduce this noise. The proposal is verified by simulations showing the maximum single-shot precision is less than 1 ps. The proposed front-end circuit can also diminish the mismatch effects.

A receiver function investigation of the Lithosphere beneath Southern California using Wavefield Iterative Deconvolution(WID)

NASA Astrophysics Data System (ADS)

Ainiwaer, A.; Gurrola, H.

2017-12-01

In traditional Ps receiver functions (RFs) imaging, PPs and PSs phases from the shallow layers (near surface and crust) can be miss stacked as Ps phases or interfere with deeper Ps phases. To overcome interference between phases, we developed a method to produce phase specific Ps, PPs and PSs receiver functions (wavefield iterative deconvolution or WID). Rather than preforming a separate deconvolution of each seismogram recorded at a station, WID processes all the seismograms from a seismic station in a single run. Each iteration of WID identifies the most prominent phase remaining in the data set, based on the shape of its wavefield (or moveout curve), and then places this phase on the appropriate phase specific RF. As a result, we produce PsRFs that are free of PPs and PSs phase; and reverberations thereof. We also produce phase specific PPsRFs and PSsRFs but moveout curves for these phases and their higher order reverberations are not as distinct from one another. So the PPsRFs and the PSsRFs are not as clean as the PsRFs. These phase specific RFs can be stacked to image 2-D or 3-D Earth structure using common conversion point (CCP) stacking or migration. We applied WID to 524 Southern California seismic stations to construct 3-D PsRF image of lithosphere beneath southern California. These CCP images exhibit a Ps phases from the Moho and the lithosphere asthenosphere boundary (LAB) that are free of interference from the crustal reverberations. The Moho and LAB were found to be deepest beneath the Sierra Nevada, Tansverse Range and Peninsular Range. Shallow Moho and Lab is apparent beneath the Inner Borderland and Salton Trough. The LAB depth that we estimate is in close agreement to recent published results that used Sp imaging (Lekic et al., 2011). We also found complicated structure beneath Mojave Block where mid crustal features are apparent and anomalous Ps phases at 60 km depth are observed beneath Western Mojave dessert.

Exchange and correlation in positronium-molecule scattering

NASA Astrophysics Data System (ADS)

Fabrikant, I. I.; Wilde, R. S.

2018-05-01

Exchange and correlations play a particularly important role in positronium (Ps) collisions with atoms and molecules, since the static potential for Ps interaction with a neutral system is zero. Theoretical description of both effects is a very challenging task. In the present work we use the free-electron-gas model to describe exchange and correlations in Ps collisions with molecules similar to the approach widely used in the theory of electron-molecule collisions. The results for exchange and correlation energies are presented as functions of the Fermi momentum of the electron gas and the Ps incident energy. Using the Thomas-Fermi model, these functions can be converted into exchange and correlation potentials for Ps interaction with molecules as functions of the distance between the projectile and the target.

Conversion of calibration curves for accurate estimation of molecular weight averages and distributions of polyether polyols by conventional size exclusion chromatography.

PubMed

Xu, Xiuqing; Yang, Xiuhan; Martin, Steven J; Mes, Edwin; Chen, Junlan; Meunier, David M

2018-08-17

Accurate measurement of molecular weight averages (M¯ n, M¯ w, M¯ z ) and molecular weight distributions (MWD) of polyether polyols by conventional SEC (size exclusion chromatography) is not as straightforward as it would appear. Conventional calibration with polystyrene (PS) standards can only provide PS apparent molecular weights which do not provide accurate estimates of polyol molecular weights. Using polyethylene oxide/polyethylene glycol (PEO/PEG) for molecular weight calibration could improve the accuracy, but the retention behavior of PEO/PEG is not stable in THF-based (tetrahydrofuran) SEC systems. In this work, two approaches for calibration curve conversion with narrow PS and polyol molecular weight standards were developed. Equations to convert PS-apparent molecular weight to polyol-apparent molecular weight were developed using both a rigorous mathematical analysis and graphical plot regression method. The conversion equations obtained by the two approaches were in good agreement. Factors influencing the conversion equation were investigated. It was concluded that the separation conditions such as column batch and operating temperature did not have significant impact on the conversion coefficients and a universal conversion equation could be obtained. With this conversion equation, more accurate estimates of molecular weight averages and MWDs for polyether polyols can be achieved from conventional PS-THF SEC calibration. Moreover, no additional experimentation is required to convert historical PS equivalent data to reasonably accurate molecular weight results. Copyright © 2018. Published by Elsevier B.V.

Phase Distribution and Selection of Partially Correlated Persistent Scatterers

NASA Astrophysics Data System (ADS)

Lien, J.; Zebker, H. A.

2012-12-01

Interferometric synthetic aperture radar (InSAR) time-series methods can effectively estimate temporal surface changes induced by geophysical phenomena. However, such methods are susceptible to decorrelation due to spatial and temporal baselines (radar pass separation), changes in orbital geometries, atmosphere, and noise. These effects limit the number of interferograms that can be used for differential analysis and obscure the deformation signal. InSAR decorrelation effects may be ameliorated by exploiting pixels that exhibit phase stability across the stack of interferograms. These so-called persistent scatterer (PS) pixels are dominated by a single point-like scatterer that remains phase-stable over the spatial and temporal baseline. By identifying a network of PS pixels for use in phase unwrapping, reliable deformation measurements may be obtained even in areas of low correlation, where traditional InSAR techniques fail to produce useful observations. Many additional pixels can be added to the PS list if we are able to identify those in which a dominant scatterer exhibits partial, rather than complete, correlation across all radar scenes. In this work, we quantify and exploit the phase stability of partially correlated PS pixels. We present a new system model for producing interferometric pixel values from a complex surface backscatter function characterized by signal-to-clutter ratio (SCR). From this model, we derive the joint probabilistic distribution for PS pixel phases in a stack of interferograms as a function of SCR and spatial baselines. This PS phase distribution generalizes previous results that assume the clutter phase contribution is uncorrelated between radar passes. We verify the analytic distribution through a series of radar scattering simulations. We use the derived joint PS phase distribution with maximum-likelihood SCR estimation to analyze an area of the Hayward Fault Zone in the San Francisco Bay Area. We obtain a series of 38 interferometric images of the area from C-band ERS radar satellite passes between May 1995 and December 2000. We compare the estimated SCRs to those calculated with previously derived PS phase distributions. Finally, we examine the PS network density resulting from varying selection thresholds of SCR and compare to other PS identification techniques.

Surface phase separation, dewetting feature size, and crystal morphology in thin films of polystyrene/poly(ε-caprolactone) blend.

PubMed

Ma, Meng; He, Zhoukun; Li, Yuhan; Chen, Feng; Wang, Ke; Zhang, Qing; Deng, Hua; Fu, Qiang

2012-12-01

Thin films of polystyrene (PS)/poly(ε-caprolactone) (PCL) blends were prepared by spin-coating and characterized by tapping mode force microscopy (AFM). Effects of the relative concentration of PS in polymer solution on the surface phase separation and dewetting feature size of the blend films were systematically studied. Due to the coupling of phase separation, dewetting, and crystallization of the blend films with the evaporation of solvent during spin-coating, different size of PS islands decorated with various PCL crystal structures including spherulite-like, flat-on individual lamellae, and flat-on dendritic crystal were obtained in the blend films by changing the film composition. The average distance of PS islands was shown to increase with the relative concentration of PS in casting solution. For a given ratio of PS/PCL, the feature size of PS appeared to increase linearly with the square of PS concentration while the PCL concentration only determined the crystal morphology of the blend films with no influence on the upper PS domain features. This is explained in terms of vertical phase separation and spinodal dewetting of the PS rich layer from the underlying PCL rich layer, leading to the upper PS dewetting process and the underlying PCL crystalline process to be mutually independent. Copyright © 2012 Elsevier Inc. All rights reserved.

Full waveform seismic AVAZ signatures of anisotropic shales by integrated rock physics and the reflectivity method

NASA Astrophysics Data System (ADS)

Liu, Xiwu; Guo, Zhiqi; Han, Xu

2018-06-01

A set of parallel vertical fractures embedded in a vertically transverse isotropy (VTI) background leads to orthorhombic anisotropy and corresponding azimuthal seismic responses. We conducted seismic modeling of full waveform amplitude variations versus azimuth (AVAZ) responses of anisotropic shale by integrating a rock physics model and a reflectivity method. The results indicate that the azimuthal variation of P-wave velocity tends to be more complicated for orthorhombic medium compared to the horizontally transverse isotropy (HTI) case, especially at high polar angles. Correspondingly, for the HTI layer in the theoretical model, the short axis of the azimuthal PP amplitudes at the top interface is parallel to the fracture strike, while the long axis at the bottom reflection directs the fracture strike. In contrast, the orthorhombic layer in the theoretical model shows distinct AVAZ responses in terms of PP reflections. Nevertheless, the azimuthal signatures of the R- and T-components of the mode-converted PS reflections show similar AVAZ features for the HTI and orthorhombic layers, which may imply that the PS responses are dominated by fractures. For the application to real data, a seismic-well tie based on upscaled data and a reflectivity method illustrate good agreement between the reference layers and the corresponding reflected events. Finally, the full waveform seismic AVAZ responses of the Longmaxi shale formation are computed for the cases of HTI and orthorhombic anisotropy for comparison. For the two cases, the azimuthal features represent differences mainly in amplitudes, while slightly in the phases of the reflected waveforms. Azimuth variations in the PP reflections from the reference layers show distinct behaviors for the HTI and orthorhombic cases, while the mode-converted PS reflections in terms of the R- and T-components show little differences in azimuthal features. It may suggest that the behaviors of the PS waves are dominated by vertically aligned fractures. This work provides further insight into the azimuthal seismic response of orthorhombic shales. The proposed method may help to improve the seismic-well tie, seismic interpretation, and inversion results using an azimuth anisotropy dataset.

Probing the Cypriot Lithosphere: Insights from Broadband Seismology

NASA Astrophysics Data System (ADS)

Ogden, C. S.; Bastow, I. D.; Pilidou, S.; Dimitriadis, I.; Iosif, P.; Constantinou, C.; Kounoudis, R.

2017-12-01

Cyprus, an island in the eastern Mediterranean Sea, is an ideal study locale for understanding both the final stages of subduction, and the internal structure of so-called `ophiolites' - rare, on-land exposures of oceanic crust. The Troodos ophiolite offers an excellent opportunity to interrogate a complete ophiolite sequence from mantle rocks to pillow lavas. However, determining its internal architecture, and that of the subducting African plate deep below it, cannot be easily achieved using traditional field geology. To address this issue, we have built a new network of five broadband seismograph stations across the island. These, along with existing permanent stations, record both local and teleseismic earthquakes that we are now using to image Cyprus' crust and mantle seismic structure. Receiver functions are time series, computed from three-component seismograms, which contain information about lithospheric seismic discontinuities. When a P-wave strikes a velocity discontinuity such as the Moho, energy is converted to S-waves (direct Ps phase). The widely-used H-K Stacking technique utilises this arrival, and subsequent crustal reverberations (PpPs and PsPs+PpSs), to calculate crustal thickness (H) and bulk-crustal Vp/Vs ratio (K). Central to the method is the assumption that the Moho produces the largest amplitude conversions, after the direct P-arrival, which is valid where the Moho is sharp. Where the Moho is gradational or upper crustal discontinuities are present, the Moho signals are weakened and masked by shallow crustal conversions, potentially rendering the H-K stacking method unreliable. Using a combination of synthetic and observed seismograms, we explore Cyprus' crustal structure and, specifically, the reliability of the H-K method in constraining it. Data quality is excellent across the island, but the receiver function Ps phase amplitude is low, and crustal reverberations are almost non-existent. Therefore, a simple, abrupt wavespeed jump at the Moho is lacking (perhaps due to the subducting African plate), and/or evidence for it is obscured by complex structure associated with the Troodos ophiolite. On-going analyses also include joint inversion of receiver functions and surface wave data, which together, are capable of resolving complex lithospheric seismic structure.

Seismic velocity structure of the crust and upper mantle beneath the Texas-Gulf of Mexico margin from joint inversion of Ps and Sp receiver functions and surface wave dispersion

NASA Astrophysics Data System (ADS)

Agrawal, M.; Pulliam, J.; Sen, M. K.

2013-12-01

The seismic structure beneath Texas Gulf Coast Plain (GCP) is determined via velocity analysis of stacked common conversion point (CCP) Ps and Sp receiver functions and surface wave dispersion. The GCP is a portion of a ocean-continental transition zone, or 'passive margin', where seismic imaging of lithospheric Earth structure via passive seismic techniques has been rare. Seismic data from a temporary array of 22 broadband stations, spaced 16-20 km apart, on a ~380-km-long profile from Matagorda Island, a barrier island in the Gulf of Mexico, to Johnson City, Texas were employed to construct a coherent image of the crust and uppermost mantle. CCP stacking was applied to data from teleseismic earthquakes to enhance the signal-to-noise ratios of converted phases, such as Ps phases. An inaccurate velocity model, used for time-to-depth conversion in CCP stacking, may produce higher errors, especially in a region of substantial lateral velocity variations. An accurate velocity model is therefore essential to constructing high quality depth-domain images. To find accurate velocity P- and S-wave models, we applied a joint modeling approach that searches for best-fitting models via simulated annealing. This joint inversion approach, which we call 'multi objective optimization in seismology' (MOOS), simultaneously models Ps receiver functions, Sp receiver functions and group velocity surface wave dispersion curves after assigning relative weights for each objective function. Weights are computed from the standard deviations of the data. Statistical tools such as the posterior parameter correlation matrix and posterior probability density (PPD) function are used to evaluate the constraints that each data type places on model parameters. They allow us to identify portions of the model that are well or poorly constrained.

Effect of Biophysical Properties of Phosphatidylserine Particle on Immune Tolerance Induction Toward Factor VIII in a Hemophilia A Mouse Model.

PubMed

Ramakrishnan, Radha; Balu-Iyer, Sathy V

2016-10-01

A major complication in the replacement therapy of Factor VIII (FVIII) for Hemophilia A is the development of unwanted immune responses. Previous studies from our laboratory have shown that pretreatment of FVIII in the presence of phosphatidylserine (PS) resulted in hyporesponsiveness to subsequent administration of FVIII alone, due to the ability of PS to convert an immunogen to a tolerogen. We investigated the importance of biophysical properties of PS liposomes on its ability to convert an immunogen to a tolerogen. PS particles were prepared differing in size, protein-lipid topology, lamellarity, and % association to FVIII keeping the composition of the particle same. PS particles were prepared in 2 different sizes with differing biophysical properties: smaller particles in the nanometer range (200 nm) and larger size particles in the micron range (2 μm). Hemophilia A animals treated with both the nanometer and micron size PS particles showed a significant reduction in anti-FVIII antibody titers when compared to animals receiving free FVIII alone. Upon rechallenge with free FVIII animals that received FVIII along with the nanometer size particle continued to show reduced antibody responses. Animals receiving the micron size particle showed a slight increase in titers although they remained significantly lower than the free FVIII treated group. Upon culture with bone marrow derived dendritic cells, the nanometer size particle showed a reduction in CD40 expression and an increase in transforming growth factor-β cytokine production, which was not observed with the micron size particle. These results show that biophysical properties of PS play an important role in tolerance. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Characterization of a transmission positron/positronium converter for antihydrogen production

NASA Astrophysics Data System (ADS)

Aghion, S.; Amsler, C.; Ariga, T.; Bonomi, G.; Brusa, R. S.; Caccia, M.; Caravita, R.; Castelli, F.; Cerchiari, G.; Comparat, D.; Consolati, G.; Demetrio, A.; Di Noto, L.; Doser, M.; Ereditato, A.; Evans, C.; Ferragut, R.; Fesel, J.; Fontana, A.; Gerber, S.; Giammarchi, M.; Gligorova, A.; Guatieri, F.; Haider, S.; Hinterberger, A.; Holmestad, H.; Kellerbauer, A.; Krasnický, D.; Lagomarsino, V.; Lansonneur, P.; Lebrun, P.; Malbrunot, C.; Mariazzi, S.; Matveev, V.; Mazzotta, Z.; Müller, S. R.; Nebbia, G.; Nedelec, P.; Oberthaler, M.; Pacifico, N.; Pagano, D.; Penasa, L.; Petracek, V.; Povolo, L.; Prelz, F.; Prevedelli, M.; Ravelli, L.; Resch, L.; Rienäcker, B.; Robert, J.; Røhne, O. M.; Rotondi, A.; Sacerdoti, M.; Sandaker, H.; Santoro, R.; Scampoli, P.; Simon, M.; Smestad, L.; Sorrentino, F.; Testera, G.; Tietje, I. C.; Widmann, E.; Yzombard, P.; Zimmer, C.; Zmeskal, J.; Zurlo, N.; Andersen, S. L.; Chevallier, J.; Uggerhøj, U. I.; Lyckegaard, F.

2017-09-01

In this work a characterization study of forward emission from a thin, meso-structured silica positron/positronium (Ps) converter following implantation of positrons in light of possible antihydrogen production is presented. The target consisted of a ∼1 μm thick ultraporous silica film e-gun evaporated onto a 20 nm carbon foil. The Ps formation and emission was studied via Single Shot Positron Annihilation Lifetime Spectroscopy measurements after implantation of pulses with 3 - 4 ·107 positrons and 10 ns temporal width. The forward emission of implanted positrons and secondary electrons was investigated with a micro-channel plate - phosphor screen assembly, connected either to a CCD camera for imaging of the impinging particles, or to a fast photomultiplier tube to extract information about their time of flight. The maximum Ps formation fraction was estimated to be ∼10%. At least 10% of the positrons implanted with an energy of 3.3 keV are forward-emitted with a scattering angle smaller than 50° and maximum kinetic energy of 1.2 keV. At least 0.1-0.2 secondary electrons per implanted positron were also found to be forward-emitted with a kinetic energy of a few eV. The possible application of this kind of positron/positronium converter for antihydrogen production is discussed.

Time-to-digital converter card for multichannel time-resolved single-photon counting applications

NASA Astrophysics Data System (ADS)

Tamborini, Davide; Portaluppi, Davide; Tisa, Simone; Tosi, Alberto

2015-03-01

We present a high performance Time-to-Digital Converter (TDC) card that provides 10 ps timing resolution and 20 ps (rms) timing precision with a programmable full-scale-range from 160 ns to 10 μs. Differential Non-Linearity (DNL) is better than 1.3% LSB (rms) and Integral Non-Linearity (INL) is 5 ps rms. Thanks to the low power consumption (400 mW) and the compact size (78 mm x 28 mm x 10 mm), this card is the building block for developing compact multichannel time-resolved instrumentation for Time-Correlated Single-Photon Counting (TCSPC). The TDC-card outputs the time measurement results together with the rates of START and STOP signals and the number of valid TDC conversions. These additional information are needed by many TCSPC-based applications, such as: Fluorescence Lifetime Imaging (FLIM), Time-of-Flight (TOF) ranging measurements, time-resolved Positron Emission Tomography (PET), single-molecule spectroscopy, Fluorescence Correlation Spectroscopy (FCS), Diffuse Optical Tomography (DOT), Optical Time-Domain Reflectometry (OTDR), quantum optics, etc.

Fatigue-propagation du melange polymere polystyrene/polyethylene

NASA Astrophysics Data System (ADS)

Bureau, Martin N.

The interrelations between the morphology of PS/HDPE and PS/SEBS/HDPE immiscible polymer blends and their mechanical behavior, namely in monotonic loading and in cyclic loading, were studied. As predicted by theory, high shear rates encountered during extrusion blending led to efficient minor phase emulsification in PS/HDPE blends for which the viscosity ratio approaches unity. Consequently, the emulsifying effect of an SEBS triblock copolymer employed as a compatibilizer was found to be negligible. In subsequent molding process, disintegration, shape relaxation and coarsening of the minor phase domains were responsible for the morphological evolution of the blends. In the compression molding process, morphological observations showed that the rate of minor phase coarsening followed the predictions of the Ostwald ripening theory, in agreement with the rheological analysis. In the injection molding process, minor phase coarsening was attributed to shear coalescence. The fatigue crack propagation behavior of injection-molded specimens of pure PS as well as of 95/5, 85/15 and 70/30 PS/HDPE blends and of 95/(0.5/4.5), 85/(1.5/13.5) and 70/(3/27) PS/(SEBS/HDPE) blends was then studied. The fatigue fracture surface features of specimens of pure PS as well as of PS/HDPE and PS/SEBS/HDPE blends were analyzed in detail in order to interpret their fatigue crack propagation behavior. In pure PS specimens, discontinuous growth bands, associated with the fracture of crazes in the plastic zone, formed at low fatigue crack growth rates, large dimple-like features at intermediate fatigue crack growth rates and fatigue striations at high fatigue crack growth rates. The fracture toughness of injection-molded specimens of pure PS as well as of 95/5, 85/15 and 70/30 PS/HDPE blends and of 95/(0.5/4.5) PS/(SEBS/HDPE), 85/(1.5/13.5) and 70/(3/27) PS/(SEBS/HDPE) was finally studied. The results showed that the addition of HDPE to PS led to a reduction of the fracture toughness KQ following ASTM E-399 when compared to that of pure PS. This effect was attributed to the very fine minor phase morphology of the blends obtained after extrusion blending and injection molding. (Abstract shortened by UMI.)

A 41 ps ASIC time-to-digital converter for physics experiments

NASA Astrophysics Data System (ADS)

Russo, Stefano; Petra, Nicola; De Caro, Davide; Barbarino, Giancarlo; Strollo, Antonio G. M.

2011-12-01

We present a novel Time-to-Digital (TDC) converter for physics experiments. Proposed TDC is based on a synchronous counter and an asynchronous fine interpolator. The fine part of the measurement is obtained using NORA inverters that provide improved resolution. A prototype IC was fabricated in 180 nm CMOS technology. Experimental measurements show that proposed TDC features 41 ps resolution associated with 0.35LSB differential non-linearity, 0.77LSB integral non-linearity and a negligible single shot precision. The whole dynamic range is equal to 18 μs. The proposed TDC is designed using a flash architecture that reduces dead time. Data reported in the paper show that our design is well suited for present and future particle physics experiments.

Identification of seismic anomalies caused by gas saturation on the basis of theoretical P and PS wavefield in the Carpathian Foredeep, SE Poland

NASA Astrophysics Data System (ADS)

Pietsch, Kaja; Marzec, Paweł; Kobylarski, Marcin; Danek, Tomasz; Leśniak, Andrzej; Tatarata, Artur; Gruszczyk, Edward

2007-06-01

The thin-layer build of the Carpathian Foredeep Miocene formations and large petrophysical parameter variation cause seismic images of gas-saturated zones to be ambiguous, and the location of prospection wells on the basis of anomalous seismic record is risky. A method that assists reservoir interpretation of standard recorded seismic profiles (P waves) can be a converted wave recording (PS waves). This paper presents the results of application of a multicomponent seismic survey for the reservoir interpretation over the Chałupki Dębniańskie gas deposit, carried out for the first time in Poland by Geofizyka Kraków Ltd. for the Polish Oil and Gas Company. Seismic modeling was applied as the basic research tool, using the SeisMod program based on the finite-difference solution of the acoustic wave equation and equations of motion. Seismogeological models for P waves were developed using Acoustic Logs; S-wave model (records only from part of the well) was developed on the basis of theoretical curves calculated by means of the Estymacja program calibrated with average S-velocities, calculated by correlation of recorded P and PS wavefields with 1D modeling. The conformity between theoretical and recorded wavefields makes it possible to apply the criteria established on the basis of modeling for reservoir interpretation. Direct hydrocarbon indicators (bright spots, phase change, time sag) unambiguously identify gas-prone layers within the ChD-2 prospect. A partial range of the indicators observed in the SW part of the studied profile (bright spot that covers a single, anticlinally bent seismic horizon) points to saturation of the horizon. The proposed location is confirmed by criteria determined for converted waves (continuous seismic horizons with constant, high amplitude) despite poorer agreement between theoretical and recorded wavefields.

Tuning the dielectric properties of polystyrene/poly(vinylidene fluoride) blends by selectively localizing carbon black nanoparticles.

PubMed

Zhao, Xiaodong; Zhao, Jun; Cao, Jian-Ping; Wang, Xiaoyan; Chen, Min; Dang, Zhi-Min

2013-02-28

In this work, the dielectric properties of immiscible polystyrene (PS)/poly(vinylidene fluoride) (PVDF) blends are tuned by selectively localizing carbon black (CB) nanoparticles in different phases. The PS/PVDF blends have a wide window of cocontinuity (ca. 30-80 vol % in terms of the volume fraction of PS component (v(PS))). The selective localization of CB nanoparticles is achieved by using the masterbatch process during melt mixing. For the volume ratio PS/PVDF 1/1 and the volume fraction of CB nanoparticles (v(CB)) below but close to the percolation threshold (v(c)(CB)), the selective localization of CB nanoparticles in PVDF phase produces higher dielectric constant (ε) than that in PS phase, whereas the ε of the ternary mixtures without selective localization of fillers is in the middle. For the volume ratios PS/PVDF 1/2 and 2/1, the selective location of CB nanoparticles in different phases can be used to easily tune the system from conductive to insulating or inverse, which might have potential applications in industry. The fillers are found to be "fixed" in the masterbatch of PS or PVDF component and there is no migration of the fillers to another phase occurring during the further mixing process for the mixing time up to 30 min. Furthermore, the addition of CB nanoparticles to the polymer matrix is found to induce the brittle-ductile transition in the system and increase the compatibility between the immiscible PS and PVDF components, which should benefit the mechanical properties.

Three-Dimensional Passive-Source Reverse-Time Migration of Converted Waves: The Method

NASA Astrophysics Data System (ADS)

Li, Jiahang; Shen, Yang; Zhang, Wei

2018-02-01

At seismic discontinuities in the crust and mantle, part of the compressional wave energy converts to shear wave, and vice versa. These converted waves have been widely used in receiver function (RF) studies to image discontinuity structures in the Earth. While generally successful, the conventional RF method has its limitations and is suited mostly to flat or gently dipping structures. Among the efforts to overcome the limitations of the conventional RF method is the development of the wave-theory-based, passive-source reverse-time migration (PS-RTM) for imaging complex seismic discontinuities and scatters. To date, PS-RTM has been implemented only in 2D in the Cartesian coordinate for local problems and thus has limited applicability. In this paper, we introduce a 3D PS-RTM approach in the spherical coordinate, which is better suited for regional and global problems. New computational procedures are developed to reduce artifacts and enhance migrated images, including back-propagating the main arrival and the coda containing the converted waves separately, using a modified Helmholtz decomposition operator to separate the P and S modes in the back-propagated wavefields, and applying an imaging condition that maintains a consistent polarity for a given velocity contrast. Our new approach allows us to use migration velocity models with realistic velocity discontinuities, improving accuracy of the migrated images. We present several synthetic experiments to demonstrate the method, using regional and teleseismic sources. The results show that both regional and teleseismic sources can illuminate complex structures and this method is well suited for imaging dipping interfaces and sharp lateral changes in discontinuity structures.

CdS/C60 binary nanocomposite films prepared via phase transition of PS-b-P2VP block copolymer.

PubMed

Lee, Jung-Pil; Koh, Haeng-Deog; Shin, Won-Jeong; Kang, Nam-Goo; Park, Soojin; Lee, Jae-Suk

2014-03-01

We demonstrate the well-defined control of phase transition of a polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer from spherical micelles to lamellar structures, in which CdS and C60 nanoparticles (NPs) are selectively positioned at the P2VP domains. The CdS NPs are in situ synthesized using PS-b-P2VP block copolymer templates that are self-assembled in PS-selective solvents. The CdS-PS-b-P2VP micellar structures are transformed to lamellar phase by adjusting a solvent selectivity for both blocks. In addition, a binary system of CdS/C60 embedded in PS-b-P2VP lamellar structures (CdS/C60-PS-b-P2VP) is fabricated by embedding C60 molecules into P2VP domain though charge-transfer complexation between pyridine units of PS-b-P2VP and C60 molecules. The CdS/C60-PS-b-P2VP nanostructured films are characterized by transmission electron microscopy (TEM) and UV-Vis spectrometer. Copyright © 2013 Elsevier Inc. All rights reserved.

Thermal Processing Effects on the Adhesive Strength of PS304 High Temperature Solid Lubricant Coatings

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Edmonds, Brian J.; Benoy, Patricia A.

2001-01-01

In this paper the effects of post deposition heat treatments on the cohesive and adhesive strength properties of PS304, a plasma sprayed nickel-chrome based, high temperature solid lubricant coating deposited on stainless steel, are studied. Plasma spray deposited coating samples were exposed in air at temperatures from 432 to 650 C for up to 500 hr to promote residual stress relief, enhance particle to particle bonding and increase coating to substrate bond strength. Coating pull-off strength was measured using a commercial adhesion tester that utilizes 13 mm diameter aluminum pull studs attached to the coating surface with epoxy. Pull off force was automatically recorded and converted to coating pull off strength. As deposited coating samples were also tested as a baseline. The as-deposited (untreated) samples either delaminated at the coating-substrate interface or failed internally (cohesive failure) at about 17 MPa. Samples heat treated at temperatures above 540 C for 100 hr or at 600 C or above for more than 24 hr exhibited strengths above 31 MPa, nearly a two fold increase. Coating failure occurred inside the body of the coating (cohesive failure) for nearly all of the heat-treated samples and only occasionally at the coating substrate interface (adhesive failure). Metallographic analyses of heat-treated coatings indicate that the Nickel-Chromium binder in the PS304 appears to have segregated into two phases, a high nickel matrix phase and a high chromium precipitated phase. Analysis of the precipitates indicates the presence of silicon, a constituent of a flow enhancing additive in the commercial NiCr powder. The exact nature and structure of the precipitate phase is not known. This microstructural change is believed to be partially responsible for the coating strength increase. Diffusion bonding between particles may also be playing a role. Increasing the heat treatment temperature, exposure time or both accelerate the heat treatment process. Preliminary measurements indicate that the heat treatment also results in a one time, permanent coating thickness increase of about 3%. Based upon these results, the incorporation of a heat treatment prior to final finishing has been incorporated in the application process of this coating technology.

A physical model study of converted wave amplitude variation in a reservoir of systematically aligned vertical fractures

NASA Astrophysics Data System (ADS)

Chang, C.; Sun, L.; Lin, C.; Chang, Y.; Tseng, P.

2013-12-01

The existence of fractures not only provides spaces for the residence of oils and gases reside, but it also creates pathways for migration. Characterizing a fractured reservoir thus becomes an important subject and has been widely studied by exploration geophysicists and drilling engineers. In seismic anisotropy, a reservoir of systematically aligned vertical fractures (SAVF) is often treated as a transversely isotropic medium (TIM) with a horizontal axis of symmetry (HTI). Subjecting to HTI, physical properties vary in azimuth. P-wave reflection amplitude, which is susceptible to vary in azimuth, is one of the most popular seismic attributes which is widely used to delineate the fracture strike of an SAVF reservoir. Instead of going further on analyzing P-wave signatures, in this study, we focused on evaluating the feasibility of orienting the fracture strike of an SAVF reservoir using converted (C-) wave amplitude. For a C-wave is initiated by a downward traveling P-wave that is converted on reflection to an upcoming S-wave; the behaviors of both P- and S-waves should be theoretically woven in a C-wave. In our laboratory work, finite offset reflection experiments were carried out on the azimuthal plane of a HTI model at two different offset intervals. To demonstrate the azimuthal variation of C-wave amplitude in a HTI model, reflections were acquired along the principal symmetry directions and the diagonal direction of the HTI model. Inheriting from phenomenon of S-wave splitting in a transversely isotropic medium (TIM), P-waves get converted into both the fast (S1) and slow (S2) shear modes at all azimuths outside the vertical symmetry planes, thus producing split PS-waves (PS1 and PS2). In our laboratory data, the converted PS1- (C1-) wave were observed and identified. As the azimuth varies from the strike direction to the strike normal, C1-wave amplitude exhibits itself in a way of weakening and can be view from the common-reflection-point (CRP) gathers. Therefore, in conjunction with the azimuthal velocity and the amplitude variations in the P-wave and the azimuthal polarization of the S-wave, the azimuthal variation of C-wave amplitude which is experimentally demonstrated could be considered as a valuable seismic attribute in orienting the fracture strike of a SAVF reservoir. (Key words: converted wave, transversely isotropic medium, physical modeling, amplitude, fracture)

Illuminating sesmic discontinuities with receiver functions from a dense array in Mexico City

NASA Astrophysics Data System (ADS)

Perez-Campos, X.; Rodríguez-Domínguez, M. Á.; González-López, A.; Espindola, V. H.; Quintanar, L.; Ramirez-Guzman, L.

2017-12-01

Mexico City, with close to 10 million inhabitants, has grown over a sedimentary basin, from an old dried lake. This has been a big factor in amplifying the seismic waves from large subduction earthquakes, located > 300 km away on the Pacific coast, which represents a significant hazard. For this reason, it is of great interest to improve the knowledge of the seismic structure of the city and its details on spatial variations to reduce the uncertainty in ground motion modeling. In May 2017, such array started its way in Mexico City. It consists of 18 broadband stations, that record in place for 3-5 days, moving then to a new location. In total, the city will be covered with 343 recording sites. In this work, we present preliminary results of receiver functions obtained in such array and in permanent stations of the Seismic Network of the Valley of Mexico. Despite the few teleseismic events, the small spacing between stations ( 500 m) allows identification of converted Ps phases from the Moho discontinuity, as well as other converted phases, which might be related to subtle changes in the vertical and lateral seismic structure. This Project was funded by the Secretaria de Ciencia, Tecnología e Innovación (SECITI) of Mexico City. Project SECITI/073/2016.

Design and performance of a custom ASIC digitizer for wire chamber readout in 65 nm CMOS technology

NASA Astrophysics Data System (ADS)

Lee, M. J.; Brown, D. N.; Chang, J. K.; Ding, D.; Gnani, D.; Grace, C. R.; Jones, J. A.; Kolomensky, Y. G.; von der Lippe, H.; Mcvittie, P. J.; Stettler, M. W.; Walder, J.-P.

2015-06-01

We present the design and performance of a prototype ASIC digitizer for integrated wire chamber readout, implemented in 65 nm commercial CMOS technology. Each channel of the 4-channel prototype is composed of two 16-bit Time-to-Digital Converters (TDCs), one 8-bit Analog-to-Digital Converter (ADC), a front-end preamplifier and shaper, plus digital and analog buffers that support a variety of digitization chains. The prototype has a multiplexed digital backend that executes a state machine, distributes control and timing signals, and buffers data for serial output. Laboratory bench tests measure the absolute TDC resolution between 74 ps and 480 ps, growing with the absolute delay, and a relative time resolution of 19 ps. Resolution outliers due to cross-talk between clock signals and supply or reference voltages are seen. After calibration, the ADC displays good linearity and noise performance, with an effective number of bits of 6.9. Under normal operating conditions the circuit consumes 32 mW per channel. Potential design improvements to address the resolution drift and tails are discussed.

Dual-domain point diffraction interferometer

DOEpatents

Naulleau, Patrick P.; Goldberg, Kenneth Alan

2000-01-01

A hybrid spatial/temporal-domain point diffraction interferometer (referred to as the dual-domain PS/PDI) that is capable of suppressing the scattered-reference-light noise that hinders the conventional PS/PDI is provided. The dual-domain PS/PDI combines the separate noise-suppression capabilities of the widely-used phase-shifting and Fourier-transform fringe pattern analysis methods. The dual-domain PS/PDI relies on both a more restrictive implementation of the image plane PS/PDI mask and a new analysis method to be applied to the interferograms generated and recorded by the modified PS/PDI. The more restrictive PS/PDI mask guarantees the elimination of spatial-frequency crosstalk between the signal and the scattered-light noise arising from scattered-reference-light interfering with the test beam. The new dual-domain analysis method is then used to eliminate scattered-light noise arising from both the scattered-reference-light interfering with the test beam and the scattered-reference-light interfering with the "true" pinhole-diffracted reference light. The dual-domain analysis method has also been demonstrated to provide performance enhancement when using the non-optimized standard PS/PDI design. The dual-domain PS/PDI is essentially a three-tiered filtering system composed of lowpass spatial-filtering the test-beam electric field using the more restrictive PS/PDI mask, bandpass spatial-filtering the individual interferogram irradiance frames making up the phase-shifting series, and bandpass temporal-filtering the phase-shifting series as a whole.

Induced pluripotent stem cells for regenerative medicine.

PubMed

Hirschi, Karen K; Li, Song; Roy, Krishnendu

2014-07-11

With the discovery of induced pluripotent stem (iPS) cells, it is now possible to convert differentiated somatic cells into multipotent stem cells that have the capacity to generate all cell types of adult tissues. Thus, there is a wide variety of applications for this technology, including regenerative medicine, in vitro disease modeling, and drug screening/discovery. Although biological and biochemical techniques have been well established for cell reprogramming, bioengineering technologies offer novel tools for the reprogramming, expansion, isolation, and differentiation of iPS cells. In this article, we review these bioengineering approaches for the derivation and manipulation of iPS cells and focus on their relevance to regenerative medicine.

High frequency, high time resolution time-to-digital converter employing passive resonating circuits.

PubMed

Ripamonti, Giancarlo; Abba, Andrea; Geraci, Angelo

2010-05-01

A method for measuring time intervals accurate to the picosecond range is based on phase measurements of oscillating waveforms synchronous with their beginning and/or end. The oscillation is generated by triggering an LC resonant circuit, whose capacitance is precharged. By using high Q resonators and a final active quenching of the oscillation, it is possible to conjugate high time resolution and a small measurement time, which allows a high measurement rate. Methods for fast analysis of the data are considered and discussed with reference to computing resource requirements, speed, and accuracy. Experimental tests show the feasibility of the method and a time accuracy better than 4 ps rms. Methods aimed at further reducing hardware resources are finally discussed.

Nanoscale elastic modulus variation in loaded polymeric micelle reactors.

PubMed

Solmaz, Alim; Aytun, Taner; Deuschle, Julia K; Ow-Yang, Cleva W

2012-07-17

Tapping mode atomic force microscopy (TM-AFM) enables mapping of chemical composition at the nanoscale by taking advantage of the variation in phase angle shift arising from an embedded second phase. We demonstrate that phase contrast can be attributed to the variation in elastic modulus during the imaging of zinc acetate (ZnAc)-loaded reverse polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) diblock co-polymer micelles less than 100 nm in diameter. Three sample configurations were characterized: (i) a 31.6 μm thick polystyrene (PS) support film for eliminating the substrate contribution, (ii) an unfilled PS-b-P2VP micelle supported by the same PS film, and (iii) a ZnAc-loaded PS-b-P2VP micelle supported by the same PS film. Force-indentation (F-I) curves were measured over unloaded micelles on the PS film and over loaded micelles on the PS film, using standard tapping mode probes of three different spring constants, the same cantilevers used for imaging of the samples before and after loading. For calibration of the tip geometry, nanoindentation was performed on the bare PS film. The resulting elastic modulus values extracted by applying the Hertz model were 8.26 ± 3.43 GPa over the loaded micelles and 4.17 ± 1.65 GPa over the unloaded micelles, confirming that phase contrast images of a monolayer of loaded micelles represent maps of the nanoscale chemical and mechanical variation. By calibrating the tip geometry indirectly using a known soft material, we are able to use the same standard tapping mode cantilevers for both imaging and indentation.

Study on defect properties of nanocrystalline TiO2 during phase transition by positron annihilation lifetime

NASA Astrophysics Data System (ADS)

Zheng, F.; Liu, Y.; Liu, Z.; Dai, Y.-Q.; Fang, P.-F.; Wang, S.-J.

2012-08-01

The defect properties of nanocrystalline TiO2 were investigated by positron annihilation lifetime spectroscopy (PALS) and X-ray diffraction (XRD) as a function of annealed temperature that ranged from 300 to 850 °C. Below 500 °C, the measured positron lifetimes of τ1 (200-206 ps) and τ2 (378-402 ps) revealed the existence of mono-vacancy and vacancy-clusters at grain surface and in the micro-void of intergranular region. Between 500 and 750 °C, the phase transition from anatase to rutile was probed by the variations of positron lifetime and XRD pattern. With the increasing temperature from 500 to 850 °C, the positron lifetime τ1, τ2 and its intensity I2 sharply decreased from 200 ps, 378 ps, and 60% to 135 ps, 274 ps, and 33%, respectively. The results clearly indicate that the mono-vacancy or vacancy-clusters at grain surface and micro-voids between the grains were annealed out during the phase transition.

Positronium production in cryogenic environments

NASA Astrophysics Data System (ADS)

Cooper, B. S.; Alonso, A. M.; Deller, A.; Liszkay, L.; Cassidy, D. B.

2016-03-01

We report measurements of positronium (Ps) formation following positron irradiation of mesoporous SiO2 films and Ge(100) single crystals at temperatures ranging from 12-700 K. As both of these materials generate Ps atoms via nonthermal processes, they are able to function as positron-positronium converters at cryogenic temperatures. Our data show that such Ps formation is possibly provided the targets are not compromised by adsorption of residual gas. In the case of SiO2 films, we observe a strong reduction in the Ps formation efficiency following irradiation with UV laser light (λ =243.01 nm) below 250 K, in accordance with previous observations of radiation-induced surface paramagnetic centers. Conversely, Ps emission from Ge is enhanced by irradiation with visible laser light (λ =532 nm) via a photoemission process that persists at cryogenic temperatures. Both mesoporous SiO2 films and Ge crystals were found to produce Ps efficiently in cryogenic environments. Accordingly, these materials are likely to prove useful in several areas of research, including Ps mediated antihydrogen formation conducted in the cold bore of a superconducting magnet, the production of Rydberg Ps for experiments in which the effects of black-body radiation must be minimized, and the utilization of mesoporous structures that have been modified to produce cold Ps atoms.

Phase-Shifted Eccentric Core Fiber Bragg Grating Fabricated by Electric Arc Discharge for Directional Bending Measurement.

PubMed

Ouyang, Yang; Liu, Jianxia; Xu, Xiaofeng; Zhao, Yujia; Zhou, Ai

2018-04-11

A phase-shifted eccentric core fiber Bragg grating (PS-ECFBG) fabricated by electric arc discharge (EAD) is presented and demonstrated. It is composed of a fraction of eccentric core fiber fusion spliced in between two pieces of commercial single mode fibers, where a PS-FBG was written. The EAD in this work could flexibly change the amount of phase-shift by changing the discharge number or discharge duration. Because of the offset location of the eccentric core and the ultra-narrow resonant peak of the PS-ECFBG, it has a higher accuracy for measuring the directional bend. The elongation and compression of the eccentric core keep the magnitude of phase shift still unchanged during the bending process. The bending sensitivities of the PS-ECFBG at two opposite most sensitive directions are 57.4 pm/m -1 and -51.5 pm/m -1 , respectively. Besides, the PS-ECFBG has the potential to be a tunable narrow bandpass filter, which has a wider bi-directional adjustable range because of the bending responses. The strain and temperature sensitivities of the PS-ECFBG are experimentally measured as well, which are 0.70 pm/με and 8.85 pm/°C, respectively.

Pichia stipitis Genes for Alcohol Dehydrogenase with Fermentative and Respiratory Functions

PubMed Central

Cho, Jae-yong; Jeffries, Thomas W.

1998-01-01

Two genes coding for isozymes of alcohol dehydrogenase (ADH); designated PsADH1 and PsADH2, have been identified and isolated from Pichia stipitis CBS 6054 genomic DNA by Southern hybridization to Saccharomyces cerevisiae ADH genes, and their physiological roles have been characterized through disruption. The amino acid sequences of the PsADH1 and PsADH2 isozymes are 80.5% identical to one another and are 71.9 and 74.7% identical to the S. cerevisiae ADH1 protein. They also show a high level identity with the group I ADH proteins from Kluyveromyces lactis. The PsADH isozymes are presumably localized in the cytoplasm, as they do not possess the amino-terminal extension of mitochondrion-targeted ADHs. Gene disruption studies suggest that PsADH1 plays a major role in xylose fermentation because PsADH1 disruption results in a lower growth rate and profoundly greater accumulation of xylitol. Disruption of PsADH2 does not significantly affect ethanol production or aerobic growth on ethanol as long as PsADH1 is present. The PsADH1 and PsADH2 isozymes appear to be equivalent in the ability to convert ethanol to acetaldehyde, and either is sufficient to allow cell growth on ethanol. However, disruption of both genes blocks growth on ethanol. P. stipitis strains disrupted in either PsADH1 or PsADH2 still accumulate ethanol, although in different amounts, when grown on xylose under oxygen-limited conditions. The PsADH double disruptant, which is unable to grow on ethanol, still produces ethanol from xylose at about 13% of the rate seen in the parental strain. Thus, deletion of both PsADH1 and PsADH2 blocks ethanol respiration but not production, implying a separate path for fermentation. PMID:9546172

Diffusion of liquid polystyrene into glassy poly(phenylene oxide) characterized by DSC

NASA Astrophysics Data System (ADS)

Li, Linling; Wang, Xiaoliang; Zhou, Dongshan; Xue, Gi

2013-03-01

We report a diffusion study on the polystyrene/poly(phenylene oxide) (PS/PPO) mixture consisted by the PS and PPO nanoparticles. Diffusion of liquid PS into glassy PPO (l-PS/g-PPO) is promoted by annealing the PS/PPO mixture at several temperatures below Tg of the PPO. By tracing the Tgs of the PS-rich domain behind the diffusion front using DSC, we get the relationships of PS weight fractions and diffusion front advances with the elapsed diffusion times at different diffusion temperatures using the Gordon-Taylor equation and core-shell model. We find that the plots of weight fraction of PS vs. elapsed diffusion times at different temperatures can be converted to a master curve by Time-Temperature superposition, and the shift factors obey the Arrhenius equation. Besides, the diffusion front advances of l-PS into g-PPO show an excellent agreement with the t1/2 scaling law at the beginning of the diffusion process, and the diffusion coefficients of different diffusion temperatures also obey the Arrhenius equation. We believe the diffusion mechanism for l-PS/g-PPO should be the Fickean law rather than the Case II, though there are departures of original linearity at longer diffusion times due to the limited liquid supply system. Diffusion of liquid polystyrene into glassy poly(phenylene oxide) characterized by DSC

Solid-Phase Synthesis of RNA Analogs Containing Phosphorodithioate Linkages.

PubMed

Yang, Xianbin

2017-09-18

The oligoribonucleotide phosphorodithioate (PS2-RNA) modification uses two sulfur atoms to replace two non-bridging oxygen atoms at an internucleotide phosphorodiester backbone linkage. Like a natural phosphodiester RNA backbone linkage, a PS2-modified backbone linkage is achiral at phosphorus. PS2-RNAs are highly stable to nucleases and several in vitro assays have demonstrated their biological activity. For example, PS2-RNAs silenced mRNA in vitro and bound to protein targets in the form of PS2-aptamers (thioaptamers). Thus, the interest in and promise of PS2-RNAs has drawn attention to synthesizing, isolating, and characterizing these compounds. RNA-thiophosphoramidite monomers are commercially available from AM Biotechnologies and this unit describes an effective methodology for solid-phase synthesis, deprotection, and purification of RNAs having PS2 internucleotide linkages. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

A 7.4 ps FPGA-Based TDC with a 1024-Unit Measurement Matrix

PubMed Central

Zhang, Min; Wang, Hai; Liu, Yan

2017-01-01

In this paper, a high-resolution time-to-digital converter (TDC) based on a field programmable gate array (FPGA) device is proposed and tested. During the implementation, a new architecture of TDC is proposed which consists of a measurement matrix with 1024 units. The utilization of routing resources as the delay elements distinguishes the proposed design from other existing designs, which contributes most to the device insensitivity to variations of temperature and voltage. Experimental results suggest that the measurement resolution is 7.4 ps, and the INL (integral nonlinearity) and DNL (differential nonlinearity) are 11.6 ps and 5.5 ps, which indicates that the proposed TDC offers high performance among the available TDCs. Benefitting from the FPGA platform, the proposed TDC has superiorities in easy implementation, low cost, and short development time. PMID:28420121

A 7.4 ps FPGA-Based TDC with a 1024-Unit Measurement Matrix.

PubMed

Zhang, Min; Wang, Hai; Liu, Yan

2017-04-14

In this paper, a high-resolution time-to-digital converter (TDC) based on a field programmable gate array (FPGA) device is proposed and tested. During the implementation, a new architecture of TDC is proposed which consists of a measurement matrix with 1024 units. The utilization of routing resources as the delay elements distinguishes the proposed design from other existing designs, which contributes most to the device insensitivity to variations of temperature and voltage. Experimental results suggest that the measurement resolution is 7.4 ps, and the INL (integral nonlinearity) and DNL (differential nonlinearity) are 11.6 ps and 5.5 ps, which indicates that the proposed TDC offers high performance among the available TDCs. Benefitting from the FPGA platform, the proposed TDC has superiorities in easy implementation, low cost, and short development time.

Deformation Measurement In The Hayward Fault Zone Using Partially Correlated Persistent Scatterers

NASA Astrophysics Data System (ADS)

Lien, J.; Zebker, H. A.

2013-12-01

Interferometric synthetic aperture radar (InSAR) is an effective tool for measuring temporal changes in the Earth's surface. By combining SAR phase data collected at varying times and orbit geometries, with InSAR we can produce high accuracy, wide coverage images of crustal deformation fields. Changes in the radar imaging geometry, scatterer positions, or scattering behavior between radar passes causes the measured radar return to differ, leading to a decorrelation phase term that obscures the deformation signal and prevents the use of large baseline data. Here we present a new physically-based method of modeling decorrelation from the subset of pixels with the highest intrinsic signal-to-noise ratio, the so-called persistent scatters (PS). This more complete formulation, which includes both phase and amplitude scintillations, better describes the scattering behavior of partially correlated PS pixels and leads to a more reliable selection algorithm. The new method identifies PS pixels using maximum likelihood signal-to-clutter ratio (SCR) estimation based on the joint interferometric stack phase-amplitude distribution. Our PS selection method is unique in that it considers both phase and amplitude; accounts for correlation between all possible pairs of interferometric observations; and models the effect of spatial and temporal baselines on the stack. We use the resulting maximum likelihood SCR estimate as a criterion for PS selection. We implement the partially correlated persistent scatterer technique to analyze a stack of C-band European Remote Sensing (ERS-1/2) interferometric radar data imaging the Hayward Fault Zone from 1995 to 2000. We show that our technique achieves a better trade-off between PS pixel selection accuracy and network density compared to other PS identification methods, particularly in areas of natural terrain. We then present deformation measurements obtained by the selected PS network. Our results demonstrate that the partially correlated persistent scatterer technique can attain accurate deformation measurements even in areas that suffer decorrelation due to natural terrain. The accuracy of phase unwrapping and subsequent deformation estimation on the spatially sparse PS network depends on both pixel selection accuracy and the density of the network. We find that many additional pixels can be added to the PS list if we are able to correctly identify and add those in which the scattering mechanism exhibits partial, rather than complete, correlation across all radar scenes.

Characterizing Lithospheric Thickness in Australia using Ps and Sp Scattered Waves

NASA Astrophysics Data System (ADS)

Ford, H. A.; Fischer, K. M.; Rychert, C. A.

2008-12-01

The purpose of this study is to constrain the morphology of the lithosphere-asthenosphere boundary throughout Australia using scattered waves. Prior surface wave studies have shown a correlation between lithospheric thickness and the three primary geologic provinces of Australia, with the shallowest lithosphere located beneath the Phanerozoic province to the east, and the thicker lithosphere located beneath the Proterozoic and Archean regions. To determine lithospheric thickness, waveform data from twenty permanent broadband stations spanning mainland Australia and the island of Tasmania were analyzed using Ps and Sp migration techniques. Waveform selection for each station was based on epicentral distance (35° to 80° for Ps and 55° to 80° for Sp), and event depth (no greater than 300 km for Sp). For both Ps and Sp a simultaneous deconvolution was performed on the data for each of the twenty stations, and the resulting receiver function for each station was migrated to depth. Data were binned with epicentral distance to differentiate direct discontinuity phases from crustal reverberations (for Ps) and other teleseismic arrivals (for Sp). Early results in both Ps and Sp show a clear Moho discontinuity at most stations in addition to sharp, strong crustal reverberations seen in many of the Ps images. In the eastern Phanerozoic province, a strong negative phase at 100-105 km is evident in Ps for stations CAN and EIDS. The negative phase lies within a depth range that corresponds to the negative velocity gradient between fast lithosphere and slow asthenosphere imaged by surface waves. We therefore think that it is the lithosphere- asthenosphere boundary. On the island of Tasmania, a negative phase at 70-75 km in Ps images at stations TAU and MOO also appears to be the lithosphere-asthenosphere boundary. In the Proterozoic and Archean regions of the Australian continent, initial results for both Ps and Sp migration indicate clear crustal phases, but significantly more complicated signals at mantle depths. However, at some stations along the southern edge of the thick sub-cratonic lithosphere (previously imaged by surface waves) phases exist which may represent a lithosphere-asthenosphere boundary at depths of 110-115 km. Constraining the relationship of lithospheric thickness to the age and tectonic history of the overlying crust in Australia is important for better understanding the long term evolution of the continent.

The GANDALF 128-Channel Time-to-Digital Converter

NASA Astrophysics Data System (ADS)

Büchele, M.; Fischer, H.; Herrmann, F.; Königsmann, K.; Schill, C.; Schopferer, S.

The GANDALF 6U-VME64x/VXS module has been designed to cope with a variety of readout tasks in high energy and nuclear physics experiments, in particular the COMPASS experiment at CERN. The exchangeable mezzanine cards allow for an employment of the system in very different applications such as analog-to-digital or time-to-digital conversions, coincidence matrix formation, fast pattern recognition or fast trigger generation. Based on this platform, we present a 128-channel TDC which is implemented in a single Xilinx Virtex-5 FPGA using a shifted clock sampling method. In this concept each input signal is continuously sampled by 16 flip-flops using equidistant phase-shifted clocks. Compared to previous FPGA designs, usually based on delay lines and comprising few TDC channels with resolutions in the order of 10 ps, our design permits the implementation of a large number of TDC channels with a resolution of 64 ps in a single FPGA. Predictable placement of logic components and uniform routing inside the FPGA fabric is a particular challenge of this design. We present measurement results for the time resolution and the nonlinearity of the TDC readout system.

Evaluation of enamel surface modification using PS-OCT after laser treatment to increase resistance to demineralization

NASA Astrophysics Data System (ADS)

Kim, Jin Wan; Chan, Kenneth H.; Fried, Daniel

2016-02-01

At laser intensities below ablation, carbonated hydroxyapatite in enamel is converted into a purer phase hydroxyapatite with increased acid resistance. Previous studies suggested the possibility of achieving the conversion without surface modification. This study attempts to evaluate the thresholds for the modification without additional changes in physical and optical properties of the enamel. Bovine specimens were irradiated using an RF-excited CO2 laser operating at 9.4-μm with a pulse duration of 26- μs, pulse repetition rates of 100-1000 Hz, with a Gaussian spatial beam profile - 1.4 mm in diameter. After laser treatment, the samples were subjected to acid demineralization for 48 hours to simulate acidic intraoral conditions of a caries attack. The resulting demineralization and erosion were assessed using polarization sensitive OCT (PS-OCT) and 3D digital microscopy. The images from digital microscopy demonstrated a clear delineation between laser protected zones without visual changes and zones with higher levels of demineralization and erosion. Distinct changes in the surface morphology were found within the laser treated area in accordance with the Gaussian spatial beam profile. There was significant protection from the laser in areas that were not visually altered.

A study on the morphology of polystyrene-grafted poly(ethylene-alt-tetrafluoroethylene) (ETFE) films prepared using a simultaneous radiation grafting method

NASA Astrophysics Data System (ADS)

Song, Ju-Myung; Ko, Beom-Seok; Sohn, Joon-Yong; Nho, Young Chang; Shin, Junhwa

2014-04-01

The morphology of polystyrene-grafted poly(ethylene-alt-tetrafluoroethylene) (ETFE) films prepared using a simultaneous radiation grafting method was investigated using DMA, DSC, XRD, and SAXS instruments. The DMA study indicates that the ETFE amorphous phase and PS amorphous phase are mixed well in the PS-grafted ETFE films while the ETFE crystalline phase and the PS amorphous phase are separated, suggesting that the PS chains are grafted mainly on the ETFE amorphous regions. The DSC and XRD data showed that the natural crystalline structures of ETFE in the grafted ETFE films are not affected by the degree of grafting. The SAXS profiles displayed that the inter-crystalline distance of the ETFE films increases with an increasing degree of grafting, which further implies that the PS graft chains formed by the simultaneous irradiation has a significant impact on the amorphous morphology of the resulting grafted ETFE film. Thus, these results indicate that the styrene monomers are mainly grafted on the ETFE amorphous regions during the simultaneous radiation grafting process.

Fast Timing for High-Rate Environments with Micromegas

NASA Astrophysics Data System (ADS)

Papaevangelou, Thomas; Desforge, Daniel; Ferrer-Ribas, Esther; Giomataris, Ioannis; Godinot, Cyprien; Diaz, Diego Gonzalez; Gustavsson, Thomas; Kebbiri, Mariam; Oliveri, Eraldo; Resnati, Filippo; Ropelewski, Leszek; Tsiledakis, Georgios; Veenhof, Rob; White, Sebastian

2018-02-01

The current state of the art in fast timing resolution for existing experiments is of the order of 100 ps on the time of arrival of both charged particles and electromagnetic showers. Current R&D on charged particle timing is approaching the level of 10 ps but is not primarily directed at sustained performance at high rates and under high radiation (as would be needed for HL-LHC pileup mitigation). We demonstrate aMicromegas based solution to reach this level of performance. The Micromegas acts as a photomultiplier coupled to a Cerenkovradiator front window, which produces sufficient UV photons to convert the ˜100 ps single-photoelectron jitter into a timing response of the order of 10-20 ps per incident charged particle. A prototype has been built in order to demonstrate this performance. The first laboratory tests with a pico-second laser have shown a time resolution of the order of 27 ps for ˜50 primary photoelectrons, using a bulk Micromegas readout.

[Impact of OSA Therapy on Established Polyphasic Sleep].

PubMed

Kerl, J; Dellweg, D

2018-05-23

 The prevalence of polyphasic sleep (PS) in patients with sleep apnoea (OSA) is investigated in this study. In established PS the possible impact of OSA therapy on sleep behaviour was examined.  Sleep patterns in 24 hours of initial recepted OSA patients were recorded by questionnaire (n = 163). In polyphasic sleepers the sleep patterns were reevaluated after OSA therapy initiation. In additional patients polyphasic therapy usage was investigated by telemonitoring data (n = 487). 39,6 % of the patients had PS. After OSA therapy initiation in 97,0 % of the polyphasic sleepers a monophasic device usage was established while 3,0 % had a polyphasic usage. PS was switched to monophasic sleep in 81,8 % of the patients. 15.2 % had preserved PS without device usage on daytimes. 2,9 % of the telemonitoring patients showed a polyphasic usage pattern. The prevalence of PS in OSA patients is higher than in the general population. PS is converted to monophasic sleep in 81,8 % after OSA therapy initiation. In preserved PS the majority of patients doesn't use the therapy while napping. Polyphasic device usage was 2,9 % in telemonitoring patients and 3,0 % of the controls of this study. © Georg Thieme Verlag KG Stuttgart · New York.

Investigation of the lithosphere of the Texas Gulf Coast using phase-specific Ps receiver functions produced by wavefield iterative deconvolution

NASA Astrophysics Data System (ADS)

Gurrola, H.; Berdine, A.; Pulliam, J.

2017-12-01

Interference between Ps phases and reverberations (PPs, PSs phases and reverberations thereof) make it difficult to use Ps receiver functions (RF) in regions with thick sediments. Crustal reverberations typically interfere with Ps phases from the lithosphere-asthenosphere boundary (LAB). We have developed a method to separate Ps phases from reverberations by deconvolution of all the data recorded at a seismic station by removing phases from a single wavefront at each iteration of the deconvolution (wavefield iterative deconvolution or WID). We applied WID to data collected in the Gulf Coast and Llano Front regions of Texas by the EarthScope Transportable array and by a temporary deployment of 23 broadband seismometers (deployed by Texas Tech and Baylor Universities). The 23 station temporary deployment was 300 km long; crossing from Matagorda Island onto the Llano uplift. 3-D imaging using these data shows that the deepest part of the sedimentary basin may be inboard of the coastline. The Moho beneath the Gulf Coast plain does not appear in many of the images. This could be due to interference from reverberations from shallower layers or it may indicate the lack of a strong velocity contrast at the Moho perhaps due to serpentinization of the uppermost mantle. The Moho appears to be flat, at 40 km) beneath most of the Llano uplift but may thicken to the south and thin beneath the Coastal plain. After application of WID, we were able to identify a negatively polarized Ps phase consistent with LAB depths identified in Sp RF images. The LAB appears to be 80-100 km deep beneath most of the coast but is 100 to 120 km deep beneath the Llano uplift. There are other negatively polarized phases between 160 and 200 km depths beneath the Gulf Coast and the Llano Uplift. These deeper phases may indicate that, in this region, the LAB is transitional in nature and rather than a discrete boundary.

A 780 × 800 μm2 Multichannel Digital Silicon Photomultiplier With Column-Parallel Time-to-Digital Converter and Basic Characterization

NASA Astrophysics Data System (ADS)

Mandai, Shingo; Jain, Vishwas; Charbon, Edoardo

2014-02-01

This paper presents a digital silicon photomultiplier (SiPM) partitioned in columns, whereas each column is connected to a column-parallel time-to-digital converter (TDC), in order to improve the timing resolution of single-photon detection. By reducing the number of pixels per TDC using a sharing scheme with three TDCs per column, the pixel-to-pixel skew is reduced. We report the basic characterization of the SiPM, comprising 416 single-photon avalanche diodes (SPADs); the characterization includes photon detection probability, dark count rate, afterpulsing, and crosstalk. We achieved 264-ps full-width at half maximum timing resolution of single-photon detection using a 48-fold column-parallel TDC with a temporal resolution of 51.8 ps (least significant bit), fully integrated in standard complementary metal-oxide semiconductor technology.

A Facile Synthesis of Dynamic, Shape-Changing Polymer Particles

DTIC Science & Technology

2014-04-02

utilizing functional surfactants to control the phase separation of symmetric polystyrene- b -poly(2-vinylpyr- idine) ( PS - b - P2VP ) in dispersed droplets...Figure 1. Schematic representation of a mixed surfactant strategy for controlling the self-assembly of PS - b - P2VP and the generation of particles with...surfactant mixtures to control the phase separation of the symmetric polystyrene- b -poly(2-vinylpyridine) ( PS - b - P2VP ) block copolymers (BCPs) within

Induced pluripotent stem cells: advances to applications

PubMed Central

Nelson, Timothy J; Martinez-Fernandez, Almudena; Yamada, Satsuki; Ikeda, Yasuhiro; Perez-Terzic, Carmen; Terzic, Andre

2010-01-01

Induced pluripotent stem cell (iPS) technology has enriched the armamentarium of regenerative medicine by introducing autologous pluripotent progenitor pools bioengineered from ordinary somatic tissue. Through nuclear reprogramming, patient-specific iPS cells have been derived and validated. Optimizing iPS-based methodology will ensure robust applications across discovery science, offering opportunities for the development of personalized diagnostics and targeted therapeutics. Here, we highlight the process of nuclear reprogramming of somatic tissues that, when forced to ectopically express stemness factors, are converted into bona fide pluripotent stem cells. Bioengineered stem cells acquire the genuine ability to generate replacement tissues for a wide-spectrum of diseased conditions, and have so far demonstrated therapeutic benefit upon transplantation in model systems of sickle cell anemia, Parkinson’s disease, hemophilia A, and ischemic heart disease. The field of regenerative medicine is therefore primed to adopt and incorporate iPS cell-based advancements as a next generation stem cell platforms. PMID:21165156

Reproducibility of CT Perfusion Parameters in Liver Tumors and Normal Liver

PubMed Central

Ng, Chaan S.; Chandler, Adam G.; Wei, Wei; Herron, Delise H.; Anderson, Ella F.; Kurzrock, Razelle; Charnsangavej, Chusilp

2011-01-01

Purpose: To assess the reproducibility of computed tomographic (CT) perfusion measurements in liver tumors and normal liver and effects of motion and data acquisition time on parameters. Materials and Methods: Institutional review board approval and written informed consent were obtained for this prospective study. The study complied with HIPAA regulations. Two CT perfusion scans were obtained 2–7 days apart in seven patients with liver tumors with two scanning phases (phase 1: 30-second breath-hold cine; phase 2: six intermittent free-breathing cines) spanning 135 seconds. Blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability–surface area product (PS) for tumors and normal liver were calculated from phase 1 with and without rigid registration and, for combined phases 1 and 2, with manually and rigid-registered phase 2 images, by using deconvolution modeling. Variability was assessed with within-patient coefficients of variation (CVs) and Bland-Altman analyses. Results: For tumors, BF, BV, MTT, and PS values and reproducibility varied by analytical method, the former by up to 11%, 23%, 21%, and 138%, respectively. Median PS values doubled with the addition of phase 2 data to phase 1 data. The best overall reproducibility was obtained with rigidly registered phase 1 and phase 2 images, with within-patient CVs for BF, BV, MTT, and PS of 11.2%, 14.4%, 5.5% and 12.1%, respectively. Normal liver evaluations were similar, except with marginally lower variability. Conclusion: Absolute values and reproducibility of CT perfusion parameters were markedly influenced by motion and data acquisition time. PS, in particular, probably requires data acquisition beyond a single breath hold, for which motion-correction techniques are likely necessary. © RSNA, 2011 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11110331/-/DC1 PMID:21788525

Correlation between polarization sensitive optical coherence tomography and SHG microscopy in articular cartilage

NASA Astrophysics Data System (ADS)

Zhou, Xin; Ju, Myeong Jin; Huang, Lin; Tang, Shuo

2017-02-01

Polarization-sensitive optical coherence tomography (PS-OCT) and second harmonic generation (SHG) microscopy are two imaging modalities with different resolutions, field-of-views (FOV), and contrasts, while they both have the capability of imaging collagen fibers in biological tissues. PS-OCT can measure the tissue birefringence which is induced by highly organized fibers while SHG can image the collagen fiber organization with high resolution. Articular cartilage, with abundant structural collagen fibers, is a suitable sample to study the correlation between PS-OCT and SHG microscopy. Qualitative conjecture has been made that the phase retardation measured by PS-OCT is affected by the relationship between the collagen fiber orientation and the illumination direction. Anatomical studies show that the multilayered architecture of articular cartilage can be divided into four zones from its natural surface to the subchondral bone: the superficial zone, the middle zone, the deep zone, and the calcified zone. The different zones have different collagen fiber orientations, which can be studied by the different slopes in the cumulative phase retardation in PS-OCT. An algorithm is developed based on the quantitative analysis of PS-OCT phase retardation images to analyze the microstructural features in swine articular cartilage tissues. This algorithm utilizes the depth-dependent slope changing of phase retardation A-lines to segment structural layers. The results show good consistency with the knowledge of cartilage morphology and correlation with the SHG images measured at selected depth locations. The correlation between PS-OCT and SHG microscopy shows that PS-OCT has the potential to analyze both the macro and micro characteristics of biological tissues with abundant collagen fibers and other materials that may cause birefringence.

Digital multi-channel stabilization of four-mode phase-sensitive parametric multicasting.

PubMed

Liu, Lan; Tong, Zhi; Wiberg, Andreas O J; Kuo, Bill P P; Myslivets, Evgeny; Alic, Nikola; Radic, Stojan

2014-07-28

Stable four-mode phase-sensitive (4MPS) process was investigated as a means to enhance two-pump driven parametric multicasting conversion efficiency (CE) and signal to noise ratio (SNR). Instability of multi-beam, phase sensitive (PS) device that inherently behaves as an interferometer, with output subject to ambient induced fluctuations, was addressed theoretically and experimentally. A new stabilization technique that controls phases of three input waves of the 4MPS multicaster and maximizes CE was developed and described. Stabilization relies on digital phase-locked loop (DPLL) specifically was developed to control pump phases to guarantee stable 4MPS operation that is independent of environmental fluctuations. The technique also controls a single (signal) input phase to optimize the PS-induced improvement of the CE and SNR. The new, continuous-operation DPLL has allowed for fully stabilized PS parametric broadband multicasting, demonstrating CE improvement over 20 signal copies in excess of 10 dB.

Crustal anisotropy from Moho converted Ps wave splitting and geodynamic implications in Northeastern margin of Tibetan Plateau

NASA Astrophysics Data System (ADS)

Xie, Z.; Wu, Q.; Zhang, R.

2017-12-01

Collision between Indian and Eurasian result in intense deformation and crustal shortening in the Tibetan Plateau. NE margin of Tibetan Plateau experienced complex deformation between Qilian orogen and its adjacent blocks, Alxa Block in the north and Ordos Block in the east. We focus on if there any evidences exist in the NE margin of Tibetan Plateau, which can support crustal channel flow model. China Earthquake Administration had deployed temporary seismic array which is called ChinaArray Phase Ⅱ, dense seismic stations covered NE margin of Tibetan Plateau. Seismic data recorded by 81 seismic stations is applied in this research. We calculated receiver functions with time-domain deconvolution. We selected RFs which have clear Ps phase both in radial and transverse components to measure Ps splitting owing to crustal anisotropy, and 130 pairs of anisotropy parameters of 51 seismic stations were obtained. We would like to discuss about dynamic mechanism of this area using crustal anisotropy associated with the result of SKS-splitting and surface constrains like GPS velocity. The result can be summarized as follows. The large scale of delay time imply that the crustal anisotropy mainly derives from middle to lower crust rather than upper crust. In the southeastern part of the research area, crustal anisotropy is well agree with the result computed form SKS-splitting and GPS velocity directions trending NWW-SEE or E-W direction. This result imply a vertically coherent deformation in the area as the directions of crustal anisotropy trend to be perpendicular to the direction of normal stress. In the middle and north part of the research area, the fast polarization direction of crustal anisotropy is NEE-SWW or E-W direction, parallels with direction of GPS velocity, but differ to the direction of the result of SKS-splitting. This result may imply that decoupled deformation in this area associated with middle to lower crustal flow.

Directed Self-Organization of Polymer-Grafted Nanoparticles in Polymer Thin Films

NASA Astrophysics Data System (ADS)

Zhang, Ren

The controlled organization of nanoparticle (NP) constituents into superstructures of well-defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. Surface modification of NPs with grafted polymer ligands has emerged as a versatile means to control the interaction and organization of particle constituents in polymer-matrix composite materials. In this study, by incorporating polymer-grafted nanoparticles (PGNPs) into polymeric thin films, we aim to understand and control the spatial organization of PGNPs through the interactions between polymer brush layer and matrix chains. As model systems, we investigate thermodynamic behaviors of polystyrene-tethered gold nanoparticles (denoted as AuPS) dispersed in polymer thin film matrices with identical and different chemical compositions (PS and PMMA, respectively), and evaluate the influence of external perturbation fields on directed organization of nanofillers. With the presence of unfavorable enthalpic interactions between grafted and free polymer chains (i.e. AuPS/ PMMA blend thin films), phase-separated structures are generated upon thermal annealing, characterized with morphologies ranging from discrete droplets to spinodal structures, which is consistent with composition-dependent classic binary polymer blends phase separation. The phase separation kinetics of AuPS/ PMMA blends exhibit distinct features compared to the parent PS/ PMMA homopolymer blends. We further illustrate phase-separated AuPS-rich domains can be directed into unidirectionally aligned anisotropic structures through soft-shear dynamic zone annealing (DZA-SS) process with tunable domain aspect ratios. To exert exquisite control over the shape, size and location of phase-separated PGNP domains, topographically patterned elastomer confinement is introduced to PGNP/ polymer blend thin films during thermal annealing. When the phase-separated lengthscale coincides with confined pattern dimension, long-range ordered submicron-sized AuPS domains are generated in PMMA matrices with dense and well-dispersed nanoparticle distribution. Furthermore, preferential segregation of AuPS nanoparticles at patterned mesa regions can be induced in PS matrices where enthalpic interactions are absent. This selective segregation is achieved due to the local perturbation of grafted chains when confined in a restricted space. The efficiency of this particle segregation process within patterned mesa-trench films can be tuned by changing the relative entropic confinement effects on grafted and matrix chains. This physical pattern directed PGNP organization strategy is applicable to versatile pattern geometries and nanoparticle compositions.

Vapor Phase Deposition Using Plasma Spray-PVD™

NASA Astrophysics Data System (ADS)

von Niessen, K.; Gindrat, M.; Refke, A.

2010-01-01

Plasma spray—physical vapor deposition (PS-PVD) is a low pressure plasma spray technology to deposit coatings out of the vapor phase. PS-PVD is a part of the family of new hybrid processes recently developed by Sulzer Metco AG (Switzerland) on the basis of the well-established low pressure plasma spraying (LPPS) technology. Included in this new process family are plasma spray—chemical vapor deposition (PS-CVD) and plasma spray—thin film (PS-TF) processes. In comparison to conventional vacuum plasma spraying and LPPS, these new processes use a high energy plasma gun operated at a work pressure below 2 mbar. This leads to unconventional plasma jet characteristics which can be used to obtain specific and unique coatings. An important new feature of PS-PVD is the possibility to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats, but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional PVD technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and EB-PVD coatings. This paper reports on the progress made at Sulzer Metco to develop functional coatings build up from vapor phase of oxide ceramics and metals.

Ps mantle transition zone imaging beneath the Colorado Rocky Mountains: Evidence for an upwelling hydrous mantle

NASA Astrophysics Data System (ADS)

Zhang, Zhu; Dueker, Kenneth G.; Huang, Hsin-Hua

2018-06-01

We analyze teleseismic P-to-S conversions for high-resolution imaging of the mantle transition zone beneath the Colorado Rocky Mountains using data from a dense PASSCAL seismic broadband deployment. A total of 6,021 P-to-S converted receiver functions are constructed using a multi-channel minimum-phase deconvolution method and migrated using the common converted point technique with the 3-D teleseismic P- and S-wave tomography models of Schmandt and Humphreys (2010). The image finds that the average depths of the 410-km discontinuity (the 410) and 660-km discontinuity (the 660) at 408 ± 1.9 km and 649 ± 1.6 km respectively. The peak-to-peak topography of both discontinuities is 33 km and 27 km respectively. Additionally, prominent negative polarity phases are imaged both above and below the 410. To quantify the mean properties of the low-velocity layers about 410 km, we utilize double gradient layer models parameterization to fit the mean receiver function waveform. This waveform fitting is accomplished as a grid-search using anelastic synthetic seismograms. The best-fitting model reveals that the olivine-wadsleyite phase transformation width is 21 km, which is significantly larger than anhydrous mineral physics prediction (4-10 km) (Smyth and Frost, 2002). The findings of a wide olivine-wadsleyite phase transformation and the negative polarity phases above and below the 410, suggest that the mantle, at least in the 350-450 km depth range, is significantly hydrated. Furthermore, a conspicuous negative polarity phase below the 660 is imaged in high velocity region, we speculate the low velocity layer is due to dehydration flux melting in an area of convective downwelling. Our interpretation of these results, in tandem with the tomographic image of a Farallon slab segment at 800 km beneath the region (Schmandt and Humphreys, 2010), is that hydrous and upwelling mantle contributes to the high-standing Colorado Rocky Mountains.

Composition and structure of whey protein/gum arabic coacervates.

PubMed

Weinbreck, F; Tromp, R H; de Kruif, C G

2004-01-01

Complex coacervation in whey protein/gum arabic (WP/GA) mixtures was studied as a function of three main key parameters: pH, initial protein to polysaccharide mixing ratio (Pr:Ps)(ini), and ionic strength. Previous studies had already revealed under which conditions a coacervate phase was obtained. This study is aimed at understanding how these parameters influence the phase separation kinetics, the coacervate composition, and the internal coacervate structure. At a defined (Pr:Ps)(ini), an optimum pH of complex coacervation was found (pH(opt)), at which the strength of electrostatic interaction was maximum. For (Pr:Ps)(ini) = 2:1, the phase separation occurred the fastest and the final coacervate volume was the largest at pH(opt) = 4.0. The composition of the coacervate phase was determined after 48 h of phase separation and revealed that, at pH(opt), the coacervate phase was the most concentrated. Varying the (Pr:Ps)(ini) shifted the pH(opt) to higher values when (Pr:Ps)(ini) was increased and to lower values when (Pr:Ps)(ini) was decreased. This phenomenon was due to the level of charge compensation of the WP/GA complexes. Finally, the structure of the coacervate phase was studied with small-angle X-ray scattering (SAXS). SAXS data confirmed that at pH(opt) the coacervate phase was dense and structured. Model calculations revealed that the structure factor of WP induced a peak at Q = 0.7 nm(-1), illustrating that the coacervate phase was more structured, inducing the stronger correlation length of WP molecules. When the pH was changed to more acidic values, the correlation peak faded away, due to a more open structure of the coacervate. A shoulder in the scattering pattern of the coacervates was visible at small Q. This peak was attributed to the presence of residual charges on the GA. The peak intensity was reduced when the strength of interaction was increased, highlighting a greater charge compensation of the polyelectrolyte. Finally, increasing the ionic strength led to a less concentrated, a more heterogeneous, and a less structured coacervate phase, induced by the screening of the electrostatic interactions.

Impact of catheter ablation with remote magnetic navigation on procedural outcomes in patients with persistent and long-standing persistent atrial fibrillation.

PubMed

Jin, Qi; Pehrson, Steen; Jacobsen, Peter Karl; Chen, Xu

2015-11-01

The objectives of this study were to assess the procedural outcomes of persistent and long-standing persistent atrial fibrillation (PsAF and L-PsAF) ablation guided by remote magnetic navigation (RMN), and to detect factors predicting acute restoration of sinus rhythm (SR) by ablation with RMN. A total of 313 patients (275 male, age 59 ± 9.5 years) with PsAF (187/313) or L-PsAF (126/313) undergoing ablation using RMN were included. Patients' disease history, pulmonary venous anatomy, left atrial (LA) volume, procedure time, mapping plus ablation time, radiofrequency (RF) ablation time, fluoroscopy time, radiation dose, and complications were assessed. Stepwise regression was used to predict which variable could best predict acute restoration from AF to SR by ablation. Compared to PsAF, procedure time and RF ablation time were significantly increased in patients with L-PsAF (P = 0.01 and P < 0.001, respectively). No major complications occurred during the procedures in either PsAF or L-PsAF patients. Fifty five of 313 patients converted directly to SR by ablation. Compared to L-PsAF, the rate of SR restoration was significantly higher in PsAF (21 vs 12%, P = 0.03). Stepwise regression analysis showed LA volume was the primary parameter affecting SR restoration (P = 0.01). The LA volume of patients without direct SR restoration by ablation was 24% greater than that of patients with SR restoration (P < 0.001). Catheter ablation using RMN is a safe and effective method for PsAF and L-PsAF. LA volume could be a predictor of direct restoration of SR from sustaining AF by ablation using RMN.

Time- and frequency-dependent model of time-resolved coherent anti-Stokes Raman scattering (CARS) with a picosecond-duration probe pulse

NASA Astrophysics Data System (ADS)

Stauffer, Hans U.; Miller, Joseph D.; Slipchenko, Mikhail N.; Meyer, Terrence R.; Prince, Benjamin D.; Roy, Sukesh; Gord, James R.

2014-01-01

The hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) technique presents a promising alternative to either fs time-resolved or ps frequency-resolved CARS in both gas-phase thermometry and condensed-phase excited-state dynamics applications. A theoretical description of time-dependent CARS is used to examine this recently developed probe technique, and quantitative comparisons of the full time-frequency evolution show excellent accuracy in predicting the experimental vibrational CARS spectra obtained for two model systems. The interrelated time- and frequency-domain spectral signatures of gas-phase species produced by hybrid fs/ps CARS are explored with a focus on gas-phase N2 vibrational CARS, which is commonly used as a thermometric diagnostic of combusting flows. In particular, we discuss the merits of the simple top-hat spectral filter typically used to generate the ps-duration hybrid fs/ps CARS probe pulse, including strong discrimination against non-resonant background that often contaminates CARS signal. It is further demonstrated, via comparison with vibrational CARS results on a time-evolving solvated organic chromophore, that this top-hat probe-pulse configuration can provide improved spectral resolution, although the degree of improvement depends on the dephasing timescales of the observed molecular modes and the duration and timing of the narrowband final pulse. Additionally, we discuss the virtues of a frequency-domain Lorentzian probe-pulse lineshape and its potential for improving the hybrid fs/ps CARS technique as a diagnostic in high-pressure gas-phase thermometry applications.

Time- and frequency-dependent model of time-resolved coherent anti-Stokes Raman scattering (CARS) with a picosecond-duration probe pulse.

PubMed

Stauffer, Hans U; Miller, Joseph D; Slipchenko, Mikhail N; Meyer, Terrence R; Prince, Benjamin D; Roy, Sukesh; Gord, James R

2014-01-14

The hybrid femtosecond∕picosecond coherent anti-Stokes Raman scattering (fs∕ps CARS) technique presents a promising alternative to either fs time-resolved or ps frequency-resolved CARS in both gas-phase thermometry and condensed-phase excited-state dynamics applications. A theoretical description of time-dependent CARS is used to examine this recently developed probe technique, and quantitative comparisons of the full time-frequency evolution show excellent accuracy in predicting the experimental vibrational CARS spectra obtained for two model systems. The interrelated time- and frequency-domain spectral signatures of gas-phase species produced by hybrid fs∕ps CARS are explored with a focus on gas-phase N2 vibrational CARS, which is commonly used as a thermometric diagnostic of combusting flows. In particular, we discuss the merits of the simple top-hat spectral filter typically used to generate the ps-duration hybrid fs∕ps CARS probe pulse, including strong discrimination against non-resonant background that often contaminates CARS signal. It is further demonstrated, via comparison with vibrational CARS results on a time-evolving solvated organic chromophore, that this top-hat probe-pulse configuration can provide improved spectral resolution, although the degree of improvement depends on the dephasing timescales of the observed molecular modes and the duration and timing of the narrowband final pulse. Additionally, we discuss the virtues of a frequency-domain Lorentzian probe-pulse lineshape and its potential for improving the hybrid fs∕ps CARS technique as a diagnostic in high-pressure gas-phase thermometry applications.

Application of Extended Kalman Filter in Persistant Scatterer Interferometry to Enhace the Accuracy of Unwrapping Process

NASA Astrophysics Data System (ADS)

Tavakkoli Estahbanat, A.; Dehghani, M.

2017-09-01

In interferometry technique, phases have been modulated between 0-2π. Finding the number of integer phases missed when they were wrapped is the main goal of unwrapping algorithms. Although the density of points in conventional interferometry is high, this is not effective in some cases such as large temporal baselines or noisy interferograms. Due to existing noisy pixels, not only it does not improve results, but also it leads to some unwrapping errors during interferogram unwrapping. In PS technique, because of the sparse PS pixels, scientists are confronted with a problem to unwrap phases. Due to the irregular data separation, conventional methods are sterile. Unwrapping techniques are divided in to path-independent and path-dependent in the case of unwrapping paths. A region-growing method which is a path-dependent technique has been used to unwrap PS data. In this paper an idea of EKF has been generalized on PS data. This algorithm is applied to consider the nonlinearity of PS unwrapping problem as well as conventional unwrapping problem. A pulse-pair method enhanced with singular value decomposition (SVD) has been used to estimate spectral shift from interferometric power spectral density in 7*7 local windows. Furthermore, a hybrid cost-map is used to manage the unwrapping path. This algorithm has been implemented on simulated PS data. To form a sparse dataset, A few points from regular grid are randomly selected and the RMSE of results and true unambiguous phases in presented to validate presented approach. The results of this algorithm and true unwrapped phases were completely identical.

Potentials and Limits of Sar Permanent Scatterers In Ground Deformation Monitoring

NASA Astrophysics Data System (ADS)

Rocca, F.; Colesanti, C.; Ferretti, A.; Prati, C.

The Permanent Scatterers (PS) technique allows the identification of individual radar targets particularly suitable for SAR interferometric measurements. In fact, despite its remarkable potential, spaceborne SAR Differential Interferometry (DInSAR) has not been fully exploited as a reference tool for ground deformation mapping, due to the presence of atmospheric artefacts as well as geometrical and temporal phase decorrelation. Both drawbacks are overcome in a multi-image framework of interfer- ometric data (>25-30 images) jointly used in order to properly identify and exploit the subset of image pixels corresponding to privileged reflectors, the so-called Per- manent Scatterers. Provided that at least 3-4 PS/sqkm are available, accurate phase measurements carried out on the sparse PS grid allow one to compensate data for the atmospheric phase contributions. Average ground deformation rate as well as full dis- placement time series (both along the satellite Line of Sight, LOS) are estimated with millimetric accuracy on individual PS locations. The PS subset of image pixels can be thought of as a high density (100-400 PS/sqkm, in urban areas) "natural" geode- tic network. This study aims at discussing in detail potentials and limits of the PS approach in monitoring ground deformation phenomena characterised by a complex time non-uniform evolution (Non-Linear Motion, NLM). PS results highlighting sea- sonal displacement effects beneath San Jose (Santa Clara Valley, California) are going to be discussed. The deformation occurring there is related to the seasonal variation of the ground water level in the area delimited by the Silver Creek and the San Jose fault. The San Jose PS analysis is exploited as a significant case study to assess the main requirements for a successful detection of NLM phenomena (by means of PS), and to analyse their impact on the quality of results. Particular attention will be de- voted to the effect of irregularly sampled data and missing acquisitions. The strategies used in order to isolate the phase contribution relative to time non-uniform displace- ment phenomena from other phase terms (mainly atmospheric artefacts and residual topography) are going to be illustrated. Moreover, the main aspects to be considered envisaging a synergistic use of PS results and both GPS and optical levelling data are going to be outlined. Finally, attention will be paid to key issues to be taken into account for designing future SAR missions dedicated to detection and monitoring of ground deformation phenomena.

Phase Behavior of Binary Blends of AB+AC Block Copolymers with compatible B and C blocks

NASA Astrophysics Data System (ADS)

Pryamitsyn, Victor; Ganesan, Venkat

2012-02-01

Recently the experimental studies of phase behavior of binary blends of PS-b-P2VP and PS-b-PHS demonstrated an interesting effect: blends of symmetric PS-b-P2VP and shorter symmetric (PS-b-PHS) formed cylindrical HEX and spherical BCC phases, while each pure component formed lamellas. The miscibility of P2VP and PHS is caused by the hydrogen bonding between P2VP and PHS,which can be described as a negative Flory ?-parameter between P2VP and PHS. We developed a theory of the microphase segregation of AB+AC blends of diblock copolymers based on strong stretching theory. The main result of our theory is that in the copolymer brush-like layer formed by longer B chain and shorter C chains, the attraction between B and shorter C chains causes relative stretching of short C chains and compression of longer B chains. The latter manifests in an excessive bending force towards the grafting surface (BC|AA interface). Such bending force causes a transition from a symmetric lamella phase to a HEX cylinder or BCC spherical phases with the BC phase being a ``matrix'' component. In a blend of asymmetric BCC sphere forming copolymers (where B and C segments are the minor components), such bending force may unfold BCC spherical phase to a HEX cylinder phase, or even highly uneven lamella phases.

Preparation, characterization, and immunogenicity of Haemophilus influenzae type b polysaccharide-protein conjugates

PubMed Central

1980-01-01

A method is presented for covalently bonding Haemophilus influenzae type b capsular polysaccharide (HIB Ps) to several proteins. The method is efficient and relies upon the use of adipic dihydrazide as a spacer between the capsular polysaccharide and the carrier protein. In contrast to the poor immunogenicity of the purified HIB Ps in mice and rabbits, the HIB Ps-protein conjugates induced serum anti-type b antibodies having bactericidal activity at levels shown to be protective in humans when low doses were injected subcutaneously in a saline solution. The antibody response in mice was related to the dose of the conjugates, increased with the number of injections, and could be primed by the previous injection of the carrier protein. The HIB Ps- protein conjugates were immunogenic in three different mouse strains. The importance of the carrier molecule for the enhanced immunogenicity of the HIB Ps-protein conjugates was shown by the failure of HIB Ps hybrids prepared with either the homologous polysaccharide or pneumococcus type 3 polysaccharide to induce antibodie in mice. Rabbits injected with the HIB Ps-protein conjugates emulsified in Freund's adjuvant produced high levels of serum anti-type b antibodies which induced a bactericidal effect upon H. influenzae type b organisms. It is proposed that the HIB Ps component of the polysaccharide protein conjugates has been converted to a thymic-dependent immunogen. This method may be used to prepare protein-polysaccharide conjugates with HIB Ps and other polysaccharides to be considered for human use. PMID:6967514

On a Possible Relationship between Linguistic Expertise and EEG Gamma Band Phase Synchrony

PubMed Central

Reiterer, Susanne; Pereda, Ernesto; Bhattacharya, Joydeep

2011-01-01

Recent research has shown that extensive training in and exposure to a second language can modify the language organization in the brain by causing both structural and functional changes. However it is not yet known how these changes are manifested by the dynamic brain oscillations and synchronization patterns subserving the language networks. In search for synchronization correlates of proficiency and expertise in second language acquisition, multivariate EEG signals were recorded from 44 high and low proficiency bilinguals during processing of natural language in their first and second languages. Gamma band (30–45 Hz) phase synchronization (PS) was calculated mainly by two recently developed methods: coarse-graining of Markov chains (estimating global phase synchrony, measuring the degree of PS between one electrode and all other electrodes), and phase lag index (PLI; estimating bivariate phase synchrony, measuring the degree of PS between a pair of electrodes). On comparing second versus first language processing, global PS by coarse-graining Markov chains indicated that processing of the second language needs significantly higher synchronization strength than first language. On comparing the proficiency groups, bivariate PS measure (i.e., PLI) revealed that during second language processing the low proficiency group showed stronger and broader network patterns than the high proficiency group, with interconnectivities between a left fronto-parietal network. Mean phase coherence analysis also indicated that the network activity was globally stronger in the low proficiency group during second language processing. PMID:22125542

Toward Unified Corrections of Regional Phases for Amplitude and Travel Time Effects of Heterogeneous Structure

DTIC Science & Technology

2015-11-04

Kirtland AFB, NM 87117-5776 10. SPONSOR/MONITOR’S ACRONYM(S) AFRL /RVBYE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) AFRL -RV-PS-TR-2016-0012 12. DISTRIBUTION...DISTRIBUTION LIST DTIC/OCP 8725 John J. Kingman Rd, Suite 0944 Ft Belvoir, VA 22060-6218 1 cy AFRL /RVIL Kirtland AFB, NM 87117-5776 2 cys Official... AFRL -RV-PS- TR-2016-0012 AFRL -RV-PS- TR-2016-0012 TOWARD UNIFIED CORRECTION OF REGIONAL PHASES FOR AMPLITUDE AND TRAVEL TIME EFFECTS

Toward Unified Correction of Regional Phases for Amplitude and Travel Time Effects of Heterogeneous Structure

DTIC Science & Technology

2015-11-04

Kirtland AFB, NM 87117-5776 10. SPONSOR/MONITOR’S ACRONYM(S) AFRL /RVBYE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) AFRL -RV-PS-TR-2016-0012 12. DISTRIBUTION...DISTRIBUTION LIST DTIC/OCP 8725 John J. Kingman Rd, Suite 0944 Ft Belvoir, VA 22060-6218 1 cy AFRL /RVIL Kirtland AFB, NM 87117-5776 2 cys Official... AFRL -RV-PS- TR-2016-0012 AFRL -RV-PS- TR-2016-0012 TOWARD UNIFIED CORRECTION OF REGIONAL PHASES FOR AMPLITUDE AND TRAVEL TIME EFFECTS

Impact of Phospholipids and Tocopherols on the Oxidative Stability of Soybean Oil-in-Water Emulsions.

PubMed

Samdani, Gautam K; McClements, D Julian; Decker, Eric A

2018-04-18

Phospholipids have been shown to act synergistically with tocopherols and delay lipid oxidation in bulk oil. The synergistic activity between phospholipids and tocopherols is due to the ability of amino-group-containing phospholipids (e.g., phosphatidylethanolamine (PE) and phosphatidylserine (PS)) to convert oxidized tocopherol back into tocopherols. This study shows the effect of PE and PS on the antioxidant activity of different tocopherol homologues in oil-in-water emulsions. Effect of emulsifier type on the interaction between tocopherols and phospholipids was also studied. δ-Tocopherol and PE exhibited greater antioxidant activity as compared to α-tocopherol and PE. PS displayed 1.5-3 times greater synergism than PE with Tween 20 as emulsifier whereas both PE and PS had a similar antioxidant activity in the presence of α-tocopherol when bovine serum albumin was used as the emulsifier. This study is the first to show that PE and PS can act synergistically with tocopherols to inhibit lipid oxidation in oil-in-water emulsions and can present a new clean label antioxidant strategy for food emulsions.

A 4.2 ps Time-Interval RMS Resolution Time-to-Digital Converter Using a Bin Decimation Method in an UltraScale FPGA

NASA Astrophysics Data System (ADS)

Wang, Yonggang; Liu, Chong

2016-10-01

The common solution for a field programmable gate array (FPGA)-based time-to-digital converter (TDC) is constructing a tapped delay line (TDL) for time interpolation to yield a sub-clock time resolution. The granularity and uniformity of the delay elements of TDL determine the TDC time resolution. In this paper, we propose a dual-sampling TDL architecture and a bin decimation method that could make the delay elements as small and uniform as possible, so that the implemented TDCs can achieve a high time resolution beyond the intrinsic cell delay. Two identical full hardware-based TDCs were implemented in a Xilinx UltraScale FPGA for performance evaluation. For fixed time intervals in the range from 0 to 440 ns, the average time-interval RMS resolution is measured by the two TDCs with 4.2 ps, thus the timestamp resolution of single TDC is derived as 2.97 ps. The maximum hit rate of the TDC is as high as half the system clock rate of FPGA, namely 250 MHz in our demo prototype. Because the conventional online bin-by-bin calibration is not needed, the implementation of the proposed TDC is straightforward and relatively resource-saving.

Nonlinear simulations of particle source effects on edge localized mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, J.; Tang, C. J.; Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064

2015-12-15

The effects of particle source (PS) with different intensities and located positions on Edge Localized Mode (ELM) are systematically studied with BOUT++ code. The results show the ELM size strongly decreases with increasing the PS intensity once the PS is located in the middle or bottom of the pedestal. The effects of PS on ELM depend on the located position of PS. When it is located at the top of the pedestal, peeling-ballooning (P-B) modes can extract more free energy from the pressure gradient and grow up to be a large filament at the initial crash phase and the broadeningmore » of mode spectrum can be suppressed by PS, which leads to more energy loss. When it is located in the middle or bottom of the pedestal, the extraction of free energy by P-B modes can be suppressed, and a small filament is generated. During the turbulence transport phase, the broader mode spectrum suppresses the turbulence transport when PS is located in the middle, while the zonal flow plays an important role in damping the turbulence transport when PS is located at the bottom.« less

Phase diagram of quantum critical system via local convertibility of ground state

PubMed Central

Liu, Si-Yuan; Quan, Quan; Chen, Jin-Jun; Zhang, Yu-Ran; Yang, Wen-Li; Fan, Heng

2016-01-01

We investigate the relationship between two kinds of ground-state local convertibility and quantum phase transitions in XY model. The local operations and classical communications (LOCC) convertibility is examined by the majorization relations and the entanglement-assisted local operations and classical communications (ELOCC) via Rényi entropy interception. In the phase diagram of XY model, LOCC convertibility and ELOCC convertibility of ground-states are presented and compared. It is shown that different phases in the phase diagram of XY model can have different LOCC or ELOCC convertibility, which can be used to detect the quantum phase transition. This study will enlighten extensive studies of quantum phase transitions from the perspective of local convertibility, e.g., finite-temperature phase transitions and other quantum many-body models. PMID:27381284

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bryson, Kyle C.; Lobling, Tina I.; Muller, Axel H. E.

Using ternary blends of polystyrene (PS), poly(methyl methacrylate) (PMMA), and Janus particles (JPs) with symmetric PS and PMMA hemispheres, we demonstrate the stabilization of dispersed and bicontinuous phase-separated morphologies by the interfacial adsorption of Janus particles during demixing upon solvent removal. The resulting blend morphology could be varied by changing the blend composition and JP loading. Increasing particle loading decreased the size of phase-separated domains, while altering the mixing ratio of the PS/PMMA homopolymers produced morphologies ranging from PMMA droplets in a PS matrix to PS droplets in a PMMA matrix. Notably, bicontinuous morphologies were obtained at intermediate blend compositions,more » marking the first report of highly continuous domains obtained through demixing in a polymer blend compatibilized by Janus particles. The JPs were found to assemble in a densely packed monolayer at the interface, allowing for the stabilization of bicontinuous morphologies in films above the glass transition temperature by inhibiting coarsening and coalescence of the phase-separated domains. In conclusion, the rate of solvent evaporation from the drop-cast films and the molecular weights of the homopolymers were found to greatly affect blend morphology.« less

Rapid biodegradation of plastics by mealworms (larvae of Tenebrio molitor) brings hope to solve wasteplastic pollution

NASA Astrophysics Data System (ADS)

Wu, W.; Yang, S.; Brandon, A. M.; Yang, Y.; Flanagan, J. A.; Fan, H. Q.; Cai, S. Y.; Wang, Z. Y.; Din, L. Y.; Daliang, N.; Yang, J.; Ren, J.; Tao, H. C.; Phillips, D.; Ren, N. Q.; Zhou, J.; Waymouth, R.; Criddle, C. S.

2016-12-01

Pollution of waste plastics in soil, river, ocean, landfill and potentially groundwater has been a major environment concern for decades. They include polystyrene (PS), polyethylene (PE) and others. Plastic particles could penetrate into groundwater and become potential threats to our groundwater Our recent research demonstrated that mealworm (larvae of Tenebrio molitor ), which are commercially used as animal and bird food and insect protein, can biodegrade PS and convert it to CO2 up within 48% within 12-14 hrs in mealworm gut. PS degradation was performed initially via depolymerization and then degradation within the mealworm guts. Gut microbiota plays a major role in PS biodegradation because the degradation is nearly completely inhibited when mealworms were fed with antibiotics. Physical and chemical analysis as well 13C labeled tests confirmed the biodegradation and mineralization of PS. The generality of plastic eating behavior of mealworms and biodegradation has been observed by testing mealworms from 11 different sources in China and the USA. All of the mealworms tested consume PS although at different relative rates. At ambient temperature (20-24 oC), the average daily consumption rate of PS ranged from 0.01 to 0.3 mg per 100 mealworms when fed PS alone. The mealworms also consumed low density polyethylene (LDPE) foam as sole diet. When mealworms were fed PS alone, the consumption rate and total amount consumed increased slightly as a function of temperature from 20 to 30 oC. Supplementing the diet with normal food (bran) enhanced the PS consumption rate and the total PS mass consumed. Microbial community analysis indicated that the microbial structure changed significantly after the diet was switched from normal food bran to PS or PS plus bran. PS-degrading bacterial strains have isolated and characterized. Our discoveries brings hopes to prevent or solve potential microplastics threats to groundwater.

Monte-Carlo-based phase retardation estimator for polarization sensitive optical coherence tomography

NASA Astrophysics Data System (ADS)

Duan, Lian; Makita, Shuichi; Yamanari, Masahiro; Lim, Yiheng; Yasuno, Yoshiaki

2011-08-01

A Monte-Carlo-based phase retardation estimator is developed to correct the systematic error in phase retardation measurement by polarization sensitive optical coherence tomography (PS-OCT). Recent research has revealed that the phase retardation measured by PS-OCT has a distribution that is neither symmetric nor centered at the true value. Hence, a standard mean estimator gives us erroneous estimations of phase retardation, and it degrades the performance of PS-OCT for quantitative assessment. In this paper, the noise property in phase retardation is investigated in detail by Monte-Carlo simulation and experiments. A distribution transform function is designed to eliminate the systematic error by using the result of the Monte-Carlo simulation. This distribution transformation is followed by a mean estimator. This process provides a significantly better estimation of phase retardation than a standard mean estimator. This method is validated both by numerical simulations and experiments. The application of this method to in vitro and in vivo biological samples is also demonstrated.

Subnanosecond time-to-digital converter implemented in a Kintex-7 FPGA

NASA Astrophysics Data System (ADS)

Sano, Y.; Horii, Y.; Ikeno, M.; Sasaki, O.; Tomoto, M.; Uchida, T.

2017-12-01

Time-to-digital converters (TDCs) are used in various fields, including high-energy physics. One advantage of implementing TDCs in field-programmable gate arrays (FPGAs) is the flexibility on the modification of the logics, which is useful to cope with the changes in the experimental conditions. Recent FPGAs make it possible to implement TDCs with a time resolution less than 10 ps. On the other hand, various drift chambers require a time resolution of O(0.1) ns, and a simple and easy-to-implement TDC is useful for a robust operation. Herein an eight-channel TDC with a variable bin size down to 0.28 ns is implemented in a Xilinx Kintex-7 FPGA and tested. The TDC is based on a multisampling scheme with quad phase clocks synchronised with an external reference clock. Calibration of the bin size is unnecessary if a stable reference clock is available, which is common in high-energy physics experiments. Depending on the channel, the standard deviation of the differential nonlinearity for a 0.28 ns bin size is 0.13-0.31. The performance has a negligible dependence on the temperature. The power consumption and the potential to extend the number of channels are also discussed.

Regulation of CDP-diacylglycerol synthesis and utilization by inositol and choline in Schizosaccharomyces pombe.

PubMed Central

Gaynor, P M; Greenberg, M L

1992-01-01

CDP-diacylglycerol (CDP-DG) is an important branchpoint intermediate in eucaryotic phospholipid biosynthesis and could be a key regulatory site in phospholipid metabolism. Therefore, we examined the effects of growth phase, phospholipid precursors, and the disruption of phosphatidylcholine (PC) synthesis on the membrane-associated phospholipid biosynthetic enzymes CDP-DG synthase, phosphatidylglycerolphosphate (PGP) synthase, phosphatidylinositol (PI) synthase, and phosphatidylserine (PS) synthase in cell extracts of the fission yeast Schizosaccharomyces pombe. In complete synthetic medium containing inositol, maximal expression of CDP-DG synthase, PGP synthase, PI synthase, and PS synthase in wild-type cells occurred in the exponential phase of growth and decreased two- to fourfold in the stationary phase of growth. In cells starved for inositol, this decrease in PGP synthase, PI synthase, and PS synthase expression was not observed. Starvation for inositol resulted in a twofold derepression of PGP synthase and PS synthase expression, while PI synthase expression decreased initially and then remained constant. Upon the addition of inositol to inositol-starved cells, there was a rapid and continued increase in PI synthase expression. We examined expression of these enzymes in cho2 and cho1 mutants, which are blocked in the methylation pathway for synthesis of PC. Choline starvation resulted in a decrease in PS synthase and CDP-DG synthase expression in cho1 but not cho2 cells. Expression of PGP synthase and PI synthase was not affected by choline starvation. Inositol starvation resulted in a 1.7-fold derepression of PGP synthase expression in cho2 but not cho1 cells when PC was synthesized. PS synthase expression was not depressed, while CDP-DG synthase and PI synthase expression decreased in cho2 and cho1 cells in the absence of inositol. These results demonstrate that (i) CDP-DG synthase, PGP synthase, PI synthase, and PS synthase are similarly regulated by growth phase; (ii) inositol affects the expression of PGP synthase, PI synthase, and PS synthase; (iii) disruption of the methylation pathway results in aberrant patterns of regulation of growth phase and phospholipid precursors. Important differences between S. pombe and Saccharomyces cerevisiae with regard to regulation of these enzymes are discussed. PMID:1324908

Structural and Na-ion conduction characteristics of Na 3PS xSe 4–x

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bo, Shou -Hang; Wang, Yan; Ceder, Gerbrand

The recent discovery of the isostructrual cubic Na 3PS 4 and Na 3PSe 4 as fast Na-ion conductors provided a general structural framework for the exploration of new sodium superionic conductors. In this work, we systematically investigated the structures and ionic conduction characteristics of a series of compounds with the general chemical formula of Na 3PS xSe 4–x. Synthesis of Na 3PS 4 under different conditions (e.g., temperature, reaction vessel, mass of the precursors) reveals the reactivity of the precursors with the reaction tubes, producing different polymorphs. X-ray diffraction studies on the solid solution phases Na 3PS xSe 4–x identifiedmore » a tetragonal-to-cubic phase transition with increasing Se concentration. This observation is consistent with the computed stability of the tetragonal and cubic polymorphs, where the energy difference between the two polymorphs becomes very close to zero in Se-rich compositions. Furthermore, ab initio molecular dynamic simulations suggest that the fast Na-ion conduction in Na 3PS xSe 4–x may not be causally related with the symmetry or the composition of these phases. The formation of defects, instead, enables fast Na-ion conduction in this class of materials.« less

Structural and Na-ion conduction characteristics of Na 3 PS x Se 4-x

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bo, Shou-Hang; Wang, Yan; Ceder, Gerbrand

The recent discovery of the isostructrual cubic Na 3PS 4 and Na 3PSe 4 as fast Na-ion conductors provided a general structural framework for the exploration of new sodium superionic conductors. In this work, we systematically investigated the structures and ionic conduction characteristics of a series of compounds with the general chemical formula of Na 3PS xSe 4-x. Synthesis of Na 3PS 4 under different conditions (e.g., temperature, reaction vessel, mass of the precursors) reveals the reactivity of the precursors with the reaction tubes, producing different polymorphs. X-ray diffraction studies on the solid solution phases Na 3PS xSe 4-x more » identified a tetragonal-to-cubic phase transition with increasing Se concentration. This observation is consistent with the computed stability of the tetragonal and cubic polymorphs, where the energy difference between the two polymorphs becomes very close to zero in Se-rich compositions. Furthermore, ab initio molecular dynamic simulations suggest that the fast Na-ion conduction in Na 3PS xSe 4-x may not be causally related with the symmetry or the composition of these phases. The formation of defects, instead, enables fast Na-ion conduction in this class of materials.« less

A Facile Method to Fabricate Double Gyroid as A Polymer Template for Nanohybrids

NASA Astrophysics Data System (ADS)

Wang, Hsiao-Fang; Ho, Rong-Ming

2015-03-01

Here, we suggest a facile method to acquire double gyroid (DG) phase from the self-assembly of chiral block copolymers (BCPs*), polystyrene- b-poly(L-lactide) (PS-PLLA). A wide region for the formation of DG can be found in the phase diagram of the BCPs*, suggesting that helical phase (H*) from the self-assembly of BCPs* can serve as a stepping stone for the formation of the DG due to an easy path for order-order transition from two-dimensional to three-dimensional (network) structure. Moreover, the order-order transition from metastable H* to stable DG can be expedited by blending the PS-PLLA with compatible entity. Moreover, PS-PLLA blends are prepared by using styrene oligomer (S) to fine-tune the morphologies of the blends at which the molecular weight ratio of the S and compatible PS block (r) is less than 0.1. Owing to the use of the low-molecular-weight oligomer, the increase of BCP chain mobility in the blends significantly reduces the transformation time for the order-order transition from H* to DG. Consequently, nanoporous gyroid SiO2 can be fabricated using hydrolyzed PS-PLLA blends as a template for sol-gel reaction followed by removal of the PS matrix.

Structural and Na-ion conduction characteristics of Na 3PS xSe 4–x

DOE PAGES

Bo, Shou -Hang; Wang, Yan; Ceder, Gerbrand

2016-05-19

The recent discovery of the isostructrual cubic Na 3PS 4 and Na 3PSe 4 as fast Na-ion conductors provided a general structural framework for the exploration of new sodium superionic conductors. In this work, we systematically investigated the structures and ionic conduction characteristics of a series of compounds with the general chemical formula of Na 3PS xSe 4–x. Synthesis of Na 3PS 4 under different conditions (e.g., temperature, reaction vessel, mass of the precursors) reveals the reactivity of the precursors with the reaction tubes, producing different polymorphs. X-ray diffraction studies on the solid solution phases Na 3PS xSe 4–x identifiedmore » a tetragonal-to-cubic phase transition with increasing Se concentration. This observation is consistent with the computed stability of the tetragonal and cubic polymorphs, where the energy difference between the two polymorphs becomes very close to zero in Se-rich compositions. Furthermore, ab initio molecular dynamic simulations suggest that the fast Na-ion conduction in Na 3PS xSe 4–x may not be causally related with the symmetry or the composition of these phases. The formation of defects, instead, enables fast Na-ion conduction in this class of materials.« less

Determination of inorganic arsenic in algae using bromine halogenation and on-line nonpolar solid phase extraction followed by hydride generation atomic fluorescence spectrometry.

PubMed

Zhang, Weihong; Qi, Yuehan; Qin, Deyuan; Liu, Jixin; Mao, Xuefei; Chen, Guoying; Wei, Chao; Qian, Yongzhong

2017-08-01

Accurate, stable and fast analysis of toxic inorganic arsenic (iAs) in complicated and arsenosugar-rich algae matrix is always a challenge. Herein, a novel analytical method for iAs in algae was reported, using bromine halogenation and on-line nonpolar solid phase extraction (SPE) followed by hydride generation atomic fluorescence spectrometry (HG-AFS). The separation of iAs from algae was first performed by nonpolar SPE sorbent using Br - for arsenic halogenation. Algae samples were extracted with 1% perchloric acid. Then, 1.5mL extract was reduced by 1% thiourea, and simultaneously reacted (for 30min) with 50μL of 10% KBr for converting iAs to AsBr 3 after adding 3.5mL of 70% HCl to 5mL. A polystyrene (PS) resin cartridge was employed to retain arsenicals, which were hydrolyzed, eluted from the PS resin with H 2 O, and categorized as iAs. The total iAs was quantified by HG-AFS. Under optimum conditions, the spiked recoveries of iAs in real algae samples were in the 82-96% range, and the method achieved a desirable limit of detection of 3μgkg -1 . The inter-day relative standard deviations were 4.5% and 4.1% for spiked 100 and 500μgkg -1 respectively, which proved acceptable for this method. For real algae samples analysis, the highest presence of iAs was found in sargassum fusiforme, followed by kelp, seaweed and laver. Copyright © 2017 Elsevier B.V. All rights reserved.

Generation of picosecond optical pulse based on chirp compensation

NASA Astrophysics Data System (ADS)

Sun, Xiaofeng; Yang, Jiaqian; Li, Shangyuan; Xue, Xiaoxiao; Zheng, Xiaoping; Zhou, Bingkun

2017-10-01

Picosecond optical pulses are widely used in optical communication systems, such as the optical time division multiplexing (OTDM) and photonic analog-to-digital converter (ADC). We have proposed and demonstrated a simple method to generate picosecond optical pulse using the mach-zehnder modulator (MZM), phase modulator (PM) and single model fiber (SMF). The phase modulator is used to generate a frequency chirp which varies periodically with time. The MZM is used to suppress the pedestal of the pulse and improve the performance of the pulse. The SMF is used to compensate the frequency chirp. We have carried out theoretical analysis and numerical simulation for the generation process of the picosecond optical pulse. The influence of phase shift between the modulation signals loaded on the MZM and PM is analyzed by numerical simulation and the conditions for the generation of picosecond optical pulse are given. The formula for calculating the optimum length of SMF which is used to compensate the linear chirp is given. The optical pulses with a repetition frequency of 10 GHz and a pulse width of 8.5 ps were obtained. The time-bandwidth product was as small as 1.09 and the timing jitter is as low as 83 fs.

Charge transfer reactions between gas-phase hydrated electrons, molecular oxygen and carbon dioxide at temperatures of 80-300 K.

PubMed

Akhgarnusch, Amou; Tang, Wai Kit; Zhang, Han; Siu, Chi-Kit; Beyer, Martin K

2016-09-14

The recombination reactions of gas-phase hydrated electrons (H2O)n˙(-) with CO2 and O2, as well as the charge exchange reaction of CO2˙(-)(H2O)n with O2, were studied by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry in the temperature range T = 80-300 K. Comparison of the rate constants with collision models shows that CO2 reacts with 50% collision efficiency, while O2 reacts considerably slower. Nanocalorimetry yields internally consistent results for the three reactions. Converted to room temperature condensed phase, this yields hydration enthalpies of CO2˙(-) and O2˙(-), ΔHhyd(CO2˙(-)) = -334 ± 44 kJ mol(-1) and ΔHhyd(O2˙(-)) = -404 ± 28 kJ mol(-1). Quantum chemical calculations show that the charge exchange reaction proceeds via a CO4˙(-) intermediate, which is consistent with a fully ergodic reaction and also with the small efficiency. Ab initio molecular dynamics simulations corroborate this picture and indicate that the CO4˙(-) intermediate has a lifetime significantly above the ps regime.

Morphological and physical characterization of poly(styrene-isobutylene-styrene) block copolymers and ionomers thereof

NASA Astrophysics Data System (ADS)

Baugh, Daniel Webster, III

Poly(styrene-isobutylene-styrene) block copolymers made by living cationic polymerization using a difunctional initiator and the sequential monomer addition technique were analyzed using curve-resolution software in conjunction with high-resolution GPC. Fractional precipitation and selective solvent extraction were applied to a representative sample in order to confirm the identity of contaminating species. The latter were found to be low molecular weight polystyrene homopolymer, diblock copolymer, and higher molecular weight segmented block copolymers formed by intermolecular electrophilic aromatic substitution linking reactions occurring late in the polymerization of the styrene outer blocks. Solvent-cast films of poly(styrene-isobutylene-styrene) (PS-PIB-PS) block copolymers and block ionomers were analyzed using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Four block copolymer samples with center block molecular weights of 52,000 g/mol and PS volume fractions (o sbPS) ranging from 0.17 to 0.31 were studied. All samples exhibited hexagonally packed cylinders of PS within the PIB matrix. Cylinder spacing was in the range 32 to 36 nm for most samples, while cylinder diameters varied from 14 to 21 nm. Porod analysis of the scattering data indicated the presence of isolated phase mixing and sharp phase boundaries. PS-PIB-PS block copolymers and ionomers therefrom were analyzed using dynamic mechanical analysis (DMA) and tensile testing. The study encompassed five block copolymer samples with similar PIB center blocks with molecular weights of approx52,000 g/mol and PS weight fractions ranging from 0.127 to 0.337. Ionomers were prepared from two of these materials by lightly sulfonating the PS outer blocks. Sulfonation levels varied from 1.7 to 4.7 mol % and the sodium and potassium neutralized forms were compared to the parent block copolymers. Dynamic mechanical analysis (DMA) of the block copolymer films indicated the existence of a third phase attributed to PIB chains near the PS domain interface which experience reduced mobility due to their firm attachment to the hard PS domain. The relative amount of this phase decreased in samples with larger PS blocks, while the temperature of the associated transition increased. Tensile testing showed increased tensile strength but decreased elongation at break with larger PS blocks. DMA of the ionomers indicated improved dynamic modulus at temperatures above 100spcirc$C. Tensile testing of the ionomers indicated slight improvements in tensile strength with little loss in elongation at break. PS-PIB-PS block copolymer ionomer (BCP01, center block molecular weight = 53,000 g/mole; 25.5 wt % polystyrene, 4.7% sulfonation of phenyl units, 100% neutralized with KOH) was compounded with various organic and inorganic acid salts of 2-ethylhexyl-p-dimethyl aminobenzoate (ODAB) to explore the efficacy of these compounds as ionic plasticizers. (Abstract shortened by UMI.)

Rating health and stability of engineering structures via classification indexes of InSAR Persistent Scatterers

NASA Astrophysics Data System (ADS)

Pratesi, Fabio; Tapete, Deodato; Terenzi, Gloria; Del Ventisette, Chiara; Moretti, Sandro

2015-08-01

We propose a novel set of indexes to classify the information content of Persistent Scatterers (PS) and rate the health of engineering structures at urban to local scale. PS are automatically sampled and grouped via 'control areas' coinciding with the building and its surrounding environment. Density over the 'control areas' and velocity of PS are converted respectively into: Completeness of Information Index (Ici) that reflects the PS coverage grade; and Conservation Criticality Indexes (Icc) which rate the health condition of the monument separately for the object and surrounding control areas. The deformation pattern over the structure is classified as isolated (i) or diffused (d) based on the Velocity Distribution Index (Ivd). Both Ici and Icc are rated from A to E classes using a colour-coded system that intentionally emulates an energy-efficiency scale, to encourage the exploitation of PS by stakeholders and end-users in the practise of engineering surveying. Workability and reliability of the classification indexes are demonstrated over the urban heritage of Florence, Italy, using well established ERS-1/2 (1992-2000) descending, ENVISAT (2003-2010) ascending and descending PS datasets. The indexes are designed in perspective of handling outputs from InSAR processing of higher-resolution time series.

Reprogramming fibroblasts into induced pluripotent stem cells with Bmi1

PubMed Central

Moon, Jai-Hee; Heo, June Seok; Kim, Jun Sung; Jun, Eun Kyoung; Lee, Jung Han; Kim, Aeree; Kim, Jonggun; Whang, Kwang Youn; Kang, Yong-Kook; Yeo, Seungeun; Lim, Hee-Joung; Han, Dong Wook; Kim, Dong-Wook; Oh, Sejong; Yoon, Byung Sun; Schöler, Hans R; You, Seungkwon

2011-01-01

Somatic cells can be reprogrammed into induced pluripotent stem (iPS) cells by the transcription factors Oct4, Sox2, and Klf4 in combination with c-Myc. Recently, Sox2 plus Oct4 was shown to reprogram fibroblasts and Oct4 alone was able to reprogram mouse and human neural stem cells (NSCs) into iPS cells. Here, we report that Bmi1 leads to the transdifferentiation of mouse fibroblasts into NSC-like cells, and, in combination with Oct4, can replace Sox2, Klf4 and c-Myc during the reprogramming of fibroblasts into iPS cells. Furthermore, activation of sonic hedgehog signaling (by Shh, purmorphamine, or oxysterol) compensates for the effects of Bmi1, and, in combination with Oct4, reprograms mouse embryonic and adult fibroblasts into iPS cells. One- and two-factor iPS cells are similar to mouse embryonic stem cells in their global gene expression profile, epigenetic status, and in vitro and in vivo differentiation into all three germ layers, as well as teratoma formation and germline transmission in vivo. These data support that converting fibroblasts with Bmi1 or activation of the sonic hedgehog pathway to an intermediate cell type that expresses Sox2, Klf4, and N-Myc allows iPS generation via the addition of Oct4. PMID:21709693

Gas-phase lifetimes of nucleobase analogues by picosecond pumpionization and streak techniques.

PubMed

Blaser, Susan; Frey, Hans-Martin; Heid, Cornelia G; Leutwyler, Samuel

2014-01-01

The picosecond (ps) timescale is relevant for the investigation of many molecular dynamical processes such as fluorescence, nonradiative relaxation, intramolecular vibrational relaxation, molecular rotation and intermolecular energy transfer, to name a few. While investigations of ultrafast (femtosecond) processes of biological molecules, e.g. nucleobases and their analogues in the gas phase are available, there are few investigations on the ps time scale. We have constructed a ps pump-ionization setup and a ps streak camera fluorescence apparatus for the determination of lifetimes of supersonic jet-cooled and isolated molecules and clusters. The ps pump-ionization setup was used to determine the lifetimes of the nucleobase analogue 2-aminopurine (2AP) and of two 2AP˙(H2O)n water cluster isomers with n=1 and 2. Their lifetimes lie between 150 ps and 3 ns and are strongly cluster-size dependent. The ps streak camera setup was used to determine accurate fluorescence lifetimes of the uracil analogue 2-pyridone (2PY), its self-dimer (2PY)2, two isomers of its trimer (2PY)3 and its tetramer (2PY)4, which lie in the 7-12 ns range.

An 18-ps TDC using timing adjustment and bin realignment methods in a Cyclone-IV FPGA

NASA Astrophysics Data System (ADS)

Cao, Guiping; Xia, Haojie; Dong, Ning

2018-05-01

The method commonly used to produce a field-programmable gate array (FPGA)-based time-to-digital converter (TDC) creates a tapped delay line (TDL) for time interpolation to yield high time precision. We conduct timing adjustment and bin realignment to implement a TDC in the Altera Cyclone-IV FPGA. The former tunes the carry look-up table (LUT) cell delay by changing the LUT's function through low-level primitives according to timing analysis results, while the latter realigns bins according to the timing result obtained by timing adjustment so as to create a uniform TDL with bins of equivalent width. The differential nonlinearity and time resolution can be improved by realigning the bins. After calibration, the TDC has a 18 ps root-mean-square timing resolution and a 45 ps least-significant bit resolution.

Reversible optical switching of highly confined phonon-polaritons with an ultrathin phase-change material

NASA Astrophysics Data System (ADS)

Li, Peining; Yang, Xiaosheng; Maß, Tobias W. W.; Hanss, Julian; Lewin, Martin; Michel, Ann-Katrin U.; Wuttig, Matthias; Taubner, Thomas

2016-08-01

Surface phonon-polaritons (SPhPs), collective excitations of photons coupled with phonons in polar crystals, enable strong light-matter interaction and numerous infrared nanophotonic applications. However, as the lattice vibrations are determined by the crystal structure, the dynamical control of SPhPs remains challenging. Here, we realize the all-optical, non-volatile, and reversible switching of SPhPs by controlling the structural phase of a phase-change material (PCM) employed as a switchable dielectric environment. We experimentally demonstrate optical switching of an ultrathin PCM film (down to 7 nm, <λ/1,200) with single laser pulses and detect ultra-confined SPhPs (polariton wavevector kp > 70k0, k0 = 2π/λ) in quartz. Our proof of concept allows the preparation of all-dielectric, rewritable SPhP resonators without the need for complex fabrication methods. With optimized materials and parallelized optical addressing we foresee application potential for switchable infrared nanophotonic elements, for example, imaging elements such as superlenses and hyperlenses, as well as reconfigurable metasurfaces and sensors.

Evaluation of osteoarthritis progression using polarization-sensitive optical coherence tomography

NASA Astrophysics Data System (ADS)

Nassif, Nader A.; Pierce, Mark C.; Park, B. Hyle; Cense, Barry; de Boer, Johannes F.

2004-07-01

Osteoarthritis is a prevalent medical condition that presents a diagnostic and therapeutic challenge to physicians today because of the inability to assess the integrity of the articular cartilage early in the disease. Polarization sensitive optical coherence tomography (PS-OCT) is a high resolution, non-contact imaging modality that provides cross-sectional images with additional information regarding the integrity of the collagen matrix. Using PS-OCT to image provides information regarding thickness of the articular cartilage and gives an index of biochemical changes based on alterations in optical properties (i.e. birefringence) of the tissue. We demonstrate initial experiments performed on specimens collected following total knee replacement surgery. Articular cartilage was imaged using a 1310 nm PS-OCT system where both intensity and phase images were acquired. PS-OCT images were compared with histology, and the changes in tissue optical properties were characterized. Analysis of the intensity images demonstrates differences between healthy and diseased cartilage surface and thickness. Phase maps of the tissue demonstrated distinct differences between healthy and diseased tissue. PS-OCT was able to image a gradual loss of birefringence as the tissue became more diseased. In this way, determining the rate of change of the phase provides a quantitative measure of pathology. Thus, imaging and evaluation of osteoarthritis using PS-OCT can be a useful means of quantitative assessment of the disease.

Applications of Space-Time Duality

NASA Astrophysics Data System (ADS)

Plansinis, Brent W.

The concept of space-time duality is based on a mathematical analogy between paraxial diffraction and narrowband dispersion, and has led to the development of temporal imaging systems. The first part of this thesis focuses on the development of a temporal imaging system for the Laboratory for Laser Energetics. Using an electro-optic phase modulator as a time lens, a time-to-frequency converter is constructed capable of imaging pulses between 3 and 12 ps. Numerical simulations show how this system can be improved to image the 1-30 ps range used in OMEGA-EP. By adjusting the timing between the pulse and the sinusoidal clock of the phase modulator, the pulse spectrum can be selectively narrowed, broadened, or shifted. An experimental demonstration of this effect achieved spectral narrowing and broadening by a factor of 2. Numerical simulations show narrowing by a factor of 8 is possible with modern phase modulators. The second part of this thesis explores the space-time analog of reflection and refraction from a moving refractive index boundary. From a physics perspective, a temporal boundary breaks translational symmetry in time, requiring the momentum of the photon to remain unchanged while its energy may change. This leads to a shifting and splitting of the pulse spectrum as the boundary is crossed. Equations for the reflected and transmitted frequencies and a condition for total internal reflection are found. Two of these boundaries form a temporal waveguide, which confines the pulse to a narrow temporal window. These waveguides have a finite number of modes, which do not change during propagation. A single-mode waveguide can be created, allowing only a single pulse shape to form within the waveguide. Temporal reflection and refraction produce a frequency dependent phase shift on the incident pulse, leading to interference fringes between the incident light and the reflected light. In a waveguide, this leads to self-imaging, where the pulse shape reforms periodically at finite propagation lengths. Numerical simulations are performed for the specific case where the moving boundary is produced through cross-phase modulation. In this case, the Kerr nonlinearity causes the boundary to change during propagation, leading to unique temporal and spectral behavior.

Electron-transfer dynamics of photosynthetic reaction centers in thermoresponsive soft materials.

PubMed

Laible, Philip D; Kelley, Richard F; Wasielewski, Michael R; Firestone, Millicent A

2005-12-15

Poly(ethylene glycol)-grafted, lipid-based, thermoresponsive, soft nanostructures are shown to serve as scaffolding into which reconstituted integral membrane proteins, such as the bacterial photosynthetic reaction centers (RCs) can be stabilized, and their packing arrangement, and hence photophysical properties, can be controlled. The self-assembled nanostructures exist in two distinct states: a liquid-crystalline gel phase at temperatures above 21 degrees C and a non-birefringent, reduced viscosity state at lower temperatures. Characterization of the effect of protein introduction on the mesoscopic structure of the materials by 31P NMR and small-angle X-ray scattering shows that the expanded lamellar structure of the protein-free material is retained. At reduced temperatures, however, the aggregate structure is found to convert from a two-dimensional normal hexagonal structure to a three-dimensional cubic phase upon introduction of the RCs. Structural and functional characteristics of the RCs were determined by ground-state and femtosecond transient absorption spectroscopy. Time-resolved results indicate that the kinetics of primary electron transfer for the RCs in the low-viscosity cold phase of the self-assembled nanostructures are identical to those observed in a detergent-solubilized state in buffered aqueous solutions (approximately 4 ps) over a wide range of protein concentrations and experimental conditions. This is also true for RCs held within the lamellar gel phase at low protein concentrations and at short sample storage times. In contrast are kinetics from samples that are prepared with high RC concentrations and stored for several hours, which display additional kinetic components with extended electron-transfer times (approximately 10-12 ps). This observation is tentatively attributed to energy transfer between RCs that have laterally (in-plane) organized within the lipid bilayers of the lamellar gel phase prior to charge separation. These results not only demonstrate the use of soft nanostructures as a matrix in which to stabilize and organize membrane proteins but also suggest the possibility of using them to control the interactions between proteins and thus to tune their collective optical/electronic properties.

Atomic Force Microscopy Studies of Functional and Dysfunctional Pulmonary Surfactant Films. I. Micro- and Nanostructures of Functional Pulmonary Surfactant Films and the Effect of SP-A

PubMed Central

Zuo, Yi Y.; Keating, Eleonora; Zhao, Lin; Tadayyon, Seyed M.; Veldhuizen, Ruud A. W.; Petersen, Nils O.; Possmayer, Fred

2008-01-01

Monolayers of a functional pulmonary surfactant (PS) can reach very low surface tensions well below their equilibrium value. The mechanism by which PS monolayers reach such low surface tensions and maintain film stability remains unknown. As shown previously by fluorescence microscopy, phospholipid phase transition and separation seem to be important for the normal biophysical properties of PS. This work studied phospholipid phase transitions and separations in monolayers of bovine lipid extract surfactant using atomic force microscopy. Atomic force microscopy showed phospholipid phase separation on film compression and a monolayer-to-multilayer transition at surface pressure 40–50 mN/m. The tilted-condensed phase consisted of domains not only on the micrometer scale, as detected previously by fluorescence microscopy, but also on the nanometer scale, which is below the resolution limits of conventional optical methods. The nanodomains were embedded uniformly within the liquid-expanded phase. On compression, the microdomains broke up into nanodomains, thereby appearing to contribute to tilted-condensed and liquid-expanded phase remixing. Addition of surfactant protein A altered primarily the nanodomains and promoted the formation of multilayers. We conclude that the nanodomains play a predominant role in affecting the biophysical properties of PS monolayers and the monolayer-to-multilayer transition. PMID:18212010

Interaction of Phase Singularities on Spiral Wave Tail: Reconsideration of Capturing the Excitable Gap.

PubMed

Tomii, Naoki; Yamazaki, Masatoshi; Arafune, Tatsuhiko; Kamiya, Kaichiro; Nakazawa, Kazuo; Honjo, Haruo; Shibata, Nitaro; Sakuma, Ichiro

2018-03-09

The action mechanism of stimulation toward spiral waves (SWs) owing to the complex excitation patterns that occur just after point stimulation has not yet been experimentally clarified. This study sought to test our hypothesis that the effect of capturing excitable gap of SW by stimulation can also be explained as the interaction of original phase singularity (PS) and PSs induced by the stimulation on the wave tail (WT) of the original SW. Phase variance analysis was used to quantitatively analyze the post-shock PS trajectories. In a two-dimensional subepicardial layer of Langendorff-perfused rabbit hearts, optical mapping was utilized to record the excitation pattern during stimulation. After SW was induced by S1-S2 shock, single biphasic point stimulation S3 was applied. In 70 of the S1-S2-S3 stimulation episodes applied on six hearts, the original PS was clearly observed just before the S3 point stimulation in 37 episodes. Pairwise PSs were newly induced by the S3 in 20 episodes. The original PS collided with the newly-induced PSs in 16 episodes; otherwise, they did not interact with the original PS. SW shift occurred most efficiently when the S3 shock was applied at the relative refractory period, and PS shifted in the direction of WT. Quantitative tracking of PS clarified that stimulation in desirable conditions induces pairwise PSs on WT and that the collision of PSs causes SW shift along the WT. Results of this study indicate the importance of the interaction of shock-induced excitation with the WT for effective stimulation.

Confined Pattern-Directed Assembly of Polymer-Grafted Nanoparticles in a Phase Separating Blend with a Homopolymer Matrix.

PubMed

Zhang, Ren; Lee, Bongjoon; Bockstaller, Michael R; Douglas, Jack F; Stafford, Christopher M; Kumar, Sanat K; Raghavan, Dharmaraj; Karim, Alamgir

The controlled organization of nanoparticle (NP) constituents into superstructures of well-defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. We show that the phase separation of polymer-tethered nanoparticles immersed in a chemically different polymer matrix provides an effective and scalable method for fabricating defined submicron-sized amorphous NP domains in melt polymer thin films. We investigate this phenomenon with a view towards understanding and controlling the phase separation process through directed nanoparticle assembly. In particular, we consider isothermally annealed thin films of polystyrene-grafted gold nanoparticles (AuPS) dispersed in a poly(methyl methacrylate) (PMMA) matrix. Classic binary polymer blend phase separation related morphology transitions, from discrete AuPS domains to bicontinuous to inverse domain structure with increasing nanoparticle composition is observed, yet the kinetics of the AuPS/PMMA polymer blends system exhibit unique features compared to the parent PS/PMMA homopolymer blend. We further illustrate how to pattern-align the phase-separated AuPS nanoparticle domain shape, size and location through the imposition of a simple and novel external symmetry-breaking perturbation via soft-lithography. Specifically, submicron-sized topographically patterned elastomer confinement is introduced to direct the nanoparticles into kinetically controlled long-range ordered domains, having a dense yet well-dispersed distribution of non-crystallizing nanoparticles. The simplicity, versatility and roll-to-roll adaptability of this novel method for controlled nanoparticle assembly should make it useful in creating desirable patterned nanoparticle domains for a variety of functional materials and applications.

Novel family of terpene synthases evolved from trans-isoprenyl diphosphate synthases in a flea beetle

PubMed Central

Beran, Franziska; Rahfeld, Peter; Luck, Katrin; Nagel, Raimund; Vogel, Heiko; Wielsch, Natalie; Irmisch, Sandra; Ramasamy, Srinivasan; Gershenzon, Jonathan; Heckel, David G.; Köllner, Tobias G.

2016-01-01

Sesquiterpenes play important roles in insect communication, for example as pheromones. However, no sesquiterpene synthases, the enzymes involved in construction of the basic carbon skeleton, have been identified in insects to date. We investigated the biosynthesis of the sesquiterpene (6R,7S)-himachala-9,11-diene in the crucifer flea beetle Phyllotreta striolata, a compound previously identified as a male-produced aggregation pheromone in several Phyllotreta species. A (6R,7S)-himachala-9,11-diene–producing sesquiterpene synthase activity was detected in crude beetle protein extracts, but only when (Z,E)-farnesyl diphosphate [(Z,E)-FPP] was offered as a substrate. No sequences resembling sesquiterpene synthases from plants, fungi, or bacteria were found in the P. striolata transcriptome, but we identified nine divergent putative trans-isoprenyl diphosphate synthase (trans-IDS) transcripts. Four of these putative trans-IDSs exhibited terpene synthase (TPS) activity when heterologously expressed. Recombinant PsTPS1 converted (Z,E)-FPP to (6R,7S)-himachala-9,11-diene and other sesquiterpenes observed in beetle extracts. RNAi-mediated knockdown of PsTPS1 mRNA in P. striolata males led to reduced emission of aggregation pheromone, confirming a significant role of PsTPS1 in pheromone biosynthesis. Two expressed enzymes showed genuine IDS activity, with PsIDS1 synthesizing (E,E)-FPP, whereas PsIDS3 produced neryl diphosphate, (Z,Z)-FPP, and (Z,E)-FPP. In a phylogenetic analysis, the PsTPS enzymes and PsIDS3 were clearly separated from a clade of known coleopteran trans-IDS enzymes including PsIDS1 and PsIDS2. However, the exon–intron structures of IDS and TPS genes in P. striolata are conserved, suggesting that this TPS gene family evolved from trans-IDS ancestors. PMID:26936952

LEPS2, a Phosphorus Starvation-Induced Novel Acid Phosphatase from Tomato1

PubMed Central

Baldwin, James C.; Karthikeyan, Athikkattuvalasu S.; Raghothama, Kashchandra G.

2001-01-01

Phosphate (Pi) is one of the least available plant nutrients found in the soil. A significant amount of phosphate is bound in organic forms in the rhizosphere. Phosphatases produced by plants and microbes are presumed to convert organic phosphorus into available Pi, which is absorbed by plants. In this study we describe the isolation and characterization of a novel tomato (Lycopersicon esculentum) phosphate starvation-induced gene (LePS2) representing an acid phosphatase. LePS2 is a member of a small gene family in tomato. The cDNA is 942 bp long and contains an open reading frame encoding a 269-amino acid polypeptide. The amino acid sequence of LePS2 has a significant similarity with a phosphatase from chicken. Distinct regions of the peptide also share significant identity with the members of HAD and DDDD super families of phosphohydrolases. Many plant homologs of LePS2 are found in the databases. The LePS2 transcripts are induced rapidly in tomato plant and cell culture in the absence of Pi. However, the induction is repressible in the presence of Pi. Divided root studies indicate that internal Pi levels regulate the expression of LePS2. The enhanced expression of LePS2 is a specific response to Pi starvation, and it is not affected by starvation of other nutrients or abiotic stresses. The bacterially (Escherichia coli) expressed protein exhibits phosphatase activity against the synthetic substrate p-nitrophenyl phosphate. The pH optimum of the enzyme activity suggests that LePS2 is an acid phosphatase. PMID:11161030

Ethanol production from xylose by recombinant Saccharomyces cerevisiae expressing protein-engineered NADH-preferring xylose reductase from Pichia stipitis.

PubMed

Watanabe, Seiya; Abu Saleh, Ahmed; Pack, Seung Pil; Annaluru, Narayana; Kodaki, Tsutomu; Makino, Keisuke

2007-09-01

A recombinant Saccharomyces cerevisiae strain transformed with xylose reductase (XR) and xylitol dehydrogenase (XDH) genes from Pichia stipitis (PsXR and PsXDH, respectively) has the ability to convert xylose to ethanol together with the unfavourable excretion of xylitol, which may be due to intercellular redox imbalance caused by the different coenzyme specificity between NADPH-preferring XR and NAD(+)-dependent XDH. In this study, we focused on the effect(s) of mutated NADH-preferring PsXR in fermentation. The R276H and K270R/N272D mutants were improved 52- and 146-fold, respectively, in the ratio of NADH/NADPH in catalytic efficiency [(k(cat)/K(m) with NADH)/(k(cat)/K(m) with NADPH)] compared with the wild-type (WT), which was due to decrease of k(cat) with NADPH in the R276H mutant and increase of K(m) with NADPH in the K270R/N272D mutant. Furthermore, R276H mutation led to significant thermostabilization in PsXR. The most positive effect on xylose fermentation to ethanol was found by using the Y-R276H strain, expressing PsXR R276H mutant and PsXDH WT: 20 % increase of ethanol production and 52 % decrease of xylitol excretion, compared with the Y-WT strain expressing PsXR WT and PsXDH WT. Measurement of intracellular coenzyme concentrations suggested that maintenance of the of NADPH/NADP(+) and NADH/NAD(+) ratios is important for efficient ethanol fermentation from xylose by recombinant S. cerevisiae.

Fabrication of iron (III) oxide doped polystyrene shells

NASA Astrophysics Data System (ADS)

Cai, Pei-Jun; Tang, Yong-Jian; Zhang, Lin; Du, Kai; Feng, Chang-Gen

2004-03-01

A type of iron (III) oxide doped plastic shell used for inertial confinement fusion experiments has been fabricated by emulsion techniques. Three different phases of solution (W1, O, and W2) are used for the fabrication process. The W1 phase is a 1 wt % of sodium lauryl sulfate in water. This W1 phase solution is mixed with a 3 wt % Fe2O3-polystyrene (PS) solution in benzene-dichloroethane (O phase) while stirring. The resulting emulsion (W1/O) is poured into a 3 wt % aqueous polyvinyl alcohol solution (W2 phase) while stirring. The resulting emulsion (W1/O/W2) is then heated to evaporate benzene and dichloroethane, and thus a solid Fe2O3-PS shell is formed. The diameter and wall thickness of the shells range from 150 to 500 μm and 5 to 15 μm, respectively. The average surface roughness of the shells is 40 nm, similar to that of the usual PS shells. .

Phase unwrapping with a virtual Hartmann-Shack wavefront sensor.

PubMed

Akondi, Vyas; Falldorf, Claas; Marcos, Susana; Vohnsen, Brian

2015-10-05

The use of a spatial light modulator for implementing a digital phase-shifting (PS) point diffraction interferometer (PDI) allows tunability in fringe spacing and in achieving PS without the need for mechanically moving parts. However, a small amount of detector or scatter noise could affect the accuracy of wavefront sensing. Here, a novel method of wavefront reconstruction incorporating a virtual Hartmann-Shack (HS) wavefront sensor is proposed that allows easy tuning of several wavefront sensor parameters. The proposed method was tested and compared with a Fourier unwrapping method implemented on a digital PS PDI. The rewrapping of the Fourier reconstructed wavefronts resulted in phase maps that matched well the original wrapped phase and the performance was found to be more stable and accurate than conventional methods. Through simulation studies, the superiority of the proposed virtual HS phase unwrapping method is shown in comparison with the Fourier unwrapping method in the presence of noise. Further, combining the two methods could improve accuracy when the signal-to-noise ratio is sufficiently high.

Design of a Model Management Information System (MIS) for California's Regional Occupational Centers and Programs. Final Report.

ERIC Educational Resources Information Center

Dick, James C.; And Others

The management information system (MIS) development project for California's Regional Occupational Centers and Programs (ROC/Ps) was conducted in 3 phases over a 12-month period. Phase I involved a literature review and field study to match MIS design features and development strategy with existing conditions in ROC/Ps. A decision support system…

PsRBR1 encodes a pea retinoblastoma-related protein that is phosphorylated in axillary buds during dormancy-to-growth transition

PubMed Central

Shimizu-Sato, Sae; Ike, Yoko

2007-01-01

In intact plants, cells in axillary buds are arrested at the G1 phase of the cell cycle during dormancy. In mammalian cells, the cell cycle is suppressed at the G1 phase by the activities of retinoblastoma tumor suppressor gene (RB) family proteins, depending on their phosphorylation state. Here, we report the isolation of a pea cDNA clone encoding an RB-related protein (PsRBR1, Accession No. AB012024) with a high degree of amino acid conservation in comparison with RB family proteins. PsRBR1 protein was detected as two polypeptides using an anti-PsRBR1 antibody in dormant axillary buds, whereas it was detected as three polypeptides, which were the same two polypeptides and another larger polypeptide 2 h after terminal decapitation. Both in vitro-synthesized PsPRB1 protein and lambda protein phosphatase-treated PsRBR1 protein corresponded to the smallest polypeptide detected by anti-PsRBR1 antibody, suggesting that the three polypeptides correspond to non-phosphorylated form of PsRBR1 protein, and lower- and higher-molecular mass forms of phosphorylated PsRBR1 protein. Furthermore, in vivo labeling with [32P]-inorganic phosphate indicated that PsRBR1 protein was more phosphorylated before mRNA accumulation of cell cycle regulatory genes such as PCNA. Together these findings suggest that dormancy-to-growth transition in pea axillary buds is regulated by molecular mechanisms of cell cycle control similar to those in mammals, and that the PsRBR1 protein has an important role in suppressing the cell cycle during dormancy in axillary buds. PMID:18034314

Optical signal monitoring in phase modulated optical fiber transmission systems

NASA Astrophysics Data System (ADS)

Zhao, Jian

Optical performance monitoring (OPM) is one of the essential functions for future high speed optical networks. Among the parameters to be monitored, chromatic dispersion (CD) is especially important since it has a significant impact on overall system performance. In this thesis effective CD monitoring approaches for phase-shift keying (PSK) based optical transmission systems are investigated. A number of monitoring schemes based on radio frequency (RF) spectrum analysis and delay-tap sampling are proposed and their performance evaluated. A method for dispersion monitoring of differential phase-shift keying (DPSK) signals based on RF power detection is studied. The RF power spectrum is found to increase with the increase of CD and decrease with polarization mode dispersion (PMD). The spectral power density dependence on CD is studied theoretically and then verified through simulations and experiments. The monitoring sensitivity for nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) and return-to-zero differential phase-shift keying (RZ-DPSK) based systems can reach 80ps/nm/dB and 34ps/nm/dB respectively. The scheme enables the monitoring of differential group delay (DGD) and CD simultaneously. The monitoring sensitivity of CD and DGD can reach 56.7ps/nm/dB and 3.1ps/dB using a bandpass filter. The effects of optical signal-to-noise ratio (OSNR), DGD, fiber nonlinearity and chirp on the monitoring results are investigated. Two RF pilot tones are employed for CD monitoring of DPSK signals. Specially selected pilot tone frequencies enable good monitoring sensitivity with minimum influence on the received signals. The dynamic range exceeding 35dB and monitoring sensitivity up to 9.5ps/nm/dB are achieved. Asynchronous sampling technique is employed for CD monitoring. A signed CD monitoring method for 10Gb/s NRZ-DPSK and RZ-DPSK systems using asynchronous delay-tap sampling technique is studied. The demodulated signals suffer asymmetric waveform distortion if there is a phase error (Deltaphi) in the delay interferometer (DI) and in the presence of residual CD. Using delay-tap sampling the scatter plots can reflect this signal distortion through their asymmetric characteristics. A distance ratio (DR) is defined to represent the change of the scatter plots which is directly related to the accumulated CD. The monitoring range can be up to +/-400ps/nm and to +/-720ps/nm for 10Gb/s NRZ-DPSK and RZ-DPSK signals with 450 phase error in DI. The monitoring sensitivity reaches +/-8ps/nm and CD polarity discrimination is realized. It is found that the signal degradation is related to the increment of the absolute value of CD or phase mismatch. The effect of different polarities of phase error on CD monitoring is also analyzed. The shoulders location depends on the sign of the product DLDeltaphi. If DLDeltaphi > 0, the shoulder will appear on trailing edge else the shoulder will appear on leading edge when DLDeltaphi < 0. The analysis shows that the phase error is identical to the frequency offset of optical source so a signed frequency offset monitoring is also demonstrated. The monitoring results show that the monitoring range can reach +/-2.2GHz and the monitoring sensitivity is around 27MHz. The effect of nonlinearity, OSNR and bandwidth of the lowpass filter on the proposed monitoring method has also been studied. The signed CD monitoring for 100Gb/s carrier suppressed return-to-zero differential quadrature phase-shift keying (CSRZ-DQPSK) system based on the delay-tap sampling technology is demonstrated. The monitoring range and monitoring resolution can goes up to +/-32ps/nm and +/-8ps/nm, respectively. A signed CD and optical carrier wavelength monitoring scheme using cross-correlation method for on-off keying (00K) wavelength division multiplexing (WDM) system is proposed and demonstrated. CD monitoring sensitivity is high and can be less than 10% of the bit period. Wavelength monitoring is implemented using the proposed approach. The monitoring results show that the sensitivity can reach up to 1.37ps/GHz.

Block Copolymer Composites: A Bio-Optic Synthetic System for Dynamic Control of Refractive Index

DTIC Science & Technology

2005-06-16

Wagner (interfacial) polarization of dispersed, ion-conductive phases in PS - b -PEO containing NLO-active moieties. In this initiative we postulate that...either by application of an electric or magnetic field. Technical Results Spatial modulation of refractive index in PS - b -PEO composites. Over the 18 month...segments with ionizable salts and polarizable, electrorefractive moieties and nanocrystals. Simple devices comprised of thin films of PS - b -PEO/KDP, PS - b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leung, Bonnie; Hitchcock, Adam; Brash, John

Spun-cast films of polystyrene (PS) blended with polylactide (PLA) were visualized and characterized using atomic force microscopy (AFM) and synchrotron-based X-ray photoemission electron microscopy (X-PEEM). The composition of the two polymers in these systems was determined by quantitative chemical analysis of near-edge X-ray absorption signals recorded with X-PEEM. The surface morphology depends on the ratio of the two components, the total polymer concentration, and the temperature of vacuum annealing. For most of the blends examined, PS is the continuous phase with PLA existing in discrete domains or segregated to the air?polymer interface. Phase segregation was improved with further annealing. Amore » phase inversion occurred when films of a 40:60 PS:PLA blend (0.7 wt percent loading) were annealed above the glass transition temperature (Tg) of PLA.« less

Self-organized morphological evolution and dewetting in solvent vapor annealing of spin coated polymer blend nanostructures.

PubMed

Roy, Sudeshna; Sharma, Ashutosh

2015-07-01

Dewetting pathways, kinetics and morphologies of thin films of phase separating polymer blends are governed by the relative mobilities of the two components. We characterize the morphological transformations of the nanostructures of a PS/PMMA blend by annealing in toluene and chloroform vapors. Toluene leads to faster reorganization of PS, whereas chloroform engenders the opposite effect. Spin coating produces a very rough PMMA rich layer that completely wets the substrate and forms a plethora of slender columns protruding through the continuous PS rich layer on top. The nanostructures were stable under long thermal annealing but in the vapor annealing, phase separation and dewetting occurred readily to form the equilibrium structures of dewetted droplets of PS on top of PMMA which also climbed around the PS droplets to form rims. Toluene and chloroform annealing required around 50 h and 1 h respectively to attain the equilibrium. Substantial differences are observed in the intermediate morphologies (heights of nanostructures, roughness and size). PMMA columns remained embedded in the dewetted PS droplets, whereas a high mobility of PMMA in chloroform allowed its rapid evacuation during dewetting to produce an intermediate swiss-cheese like morphology of PS domains. Copyright © 2015 Elsevier Inc. All rights reserved.

Microbial Lipid Production from Enzymatic Hydrolysate of Pecan Nutshell Pretreated by Combined Pretreatment.

PubMed

Qin, Lizhen; Qian, Hanyu; He, Yucai

2017-12-01

Biodiesel is a fuel composed of monoalkyl esters of long-chain fatty acids derived from renewable biomass sources. In this study, biomass waste pecan nutshell (PS) was attempted to be converted into microbial oil. For effective utilization of PS, sequential pretreatment with ethylene glycol-H 2 SO 4 -water (78:2:20, wt:wt:wt) at 130 °C for 30 min and aqueous ammonia (25 wt%) at 50 °C for 24 h was used to enhance its enzymatic saccharification. Significant linear correlation was obtained about delignification-saccharification (R 2  = 0.9507). SEM and FTIR results indicated that combination pretreatment could effectively remove lignin and xylan in PS for promoting its enzymatic saccharification. After 72 h, the reducing sugars from the hydrolysis of 50 g/L pretreated PS by combination pretreatment could be obtained at 73.6% yield. Using the recovered PS hydrolysates containing 20 g/L glucose as carbon source, microbial lipids produced from the PS hydrolysates by Rhodococcus opacus ACCC41043. Four fatty acids including palmitic acid (C16:0; 23.1%), palmitoleic acid (C16:1; 22.4%), stearic acid (C18:0; 15.3%), and oleic acid (C18:1; 23.9%) were distributed in total fatty acids. In conclusion, this strategy has potential application in the future.

Biodegradation and Mineralization of Polystyrene by Plastic-Eating Mealworms: Part 1. Chemical and Physical Characterization and Isotopic Tests.

PubMed

Yang, Yu; Yang, Jun; Wu, Wei-Min; Zhao, Jiao; Song, Yiling; Gao, Longcheng; Yang, Ruifu; Jiang, Lei

2015-10-20

Polystyrene (PS) is generally considered to be durable and resistant to biodegradation. Mealworms (the larvae of Tenebrio molitor Linnaeus) from different sources chew and eat Styrofoam, a common PS product. The Styrofoam was efficiently degraded in the larval gut within a retention time of less than 24 h. Fed with Styrofoam as the sole diet, the larvae lived as well as those fed with a normal diet (bran) over a period of 1 month. The analysis of fecula egested from Styrofoam-feeding larvae, using gel permeation chromatography (GPC), solid-state (13)C cross-polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR) spectroscopy, and thermogravimetric Fourier transform infrared (TG-FTIR) spectroscopy, substantiated that cleavage/depolymerization of long-chain PS molecules and the formation of depolymerized metabolites occurred in the larval gut. Within a 16 day test period, 47.7% of the ingested Styrofoam carbon was converted into CO2 and the residue (ca. 49.2%) was egested as fecula with a limited fraction incorporated into biomass (ca. 0.5%). Tests with α (13)C- or β (13)C-labeled PS confirmed that the (13)C-labeled PS was mineralized to (13)CO2 and incorporated into lipids. The discovery of the rapid biodegradation of PS in the larval gut reveals a new fate for plastic waste in the environment.

Phase-sensitive dual-inversion recovery for accelerated carotid vessel wall imaging.

PubMed

Bonanno, Gabriele; Brotman, David; Stuber, Matthias

2015-03-01

Dual-inversion recovery (DIR) is widely used for magnetic resonance vessel wall imaging. However, optimal contrast may be difficult to obtain and is subject to RR variability. Furthermore, DIR imaging is time-inefficient and multislice acquisitions may lead to prolonged scanning times. Therefore, an extension of phase-sensitive (PS) DIR is proposed for carotid vessel wall imaging. The statistical distribution of the phase signal after DIR is probed to segment carotid lumens and suppress their residual blood signal. The proposed PS-DIR technique was characterized over a broad range of inversion times. Multislice imaging was then implemented by interleaving the acquisition of 3 slices after DIR. Quantitative evaluation was then performed in healthy adult subjects and compared with conventional DIR imaging. Single-slice PS-DIR provided effective blood-signal suppression over a wide range of inversion times, enhancing wall-lumen contrast and vessel wall conspicuity for carotid arteries. Multislice PS-DIR imaging with effective blood-signal suppression is enabled. A variant of the PS-DIR method has successfully been implemented and tested for carotid vessel wall imaging. This technique removes timing constraints related to inversion recovery, enhances wall-lumen contrast, and enables a 3-fold increase in volumetric coverage at no extra cost in scanning time.

Development of an algorithm for controlling a multilevel three-phase converter

NASA Astrophysics Data System (ADS)

Taissariyeva, Kyrmyzy; Ilipbaeva, Lyazzat

2017-08-01

This work is devoted to the development of an algorithm for controlling transistors in a three-phase multilevel conversion system. The developed algorithm allows to organize a correct operation and describes the state of transistors at each moment of time when constructing a computer model of a three-phase multilevel converter. The developed algorithm of operation of transistors provides in-phase of a three-phase converter and obtaining a sinusoidal voltage curve at the converter output.

Increased chymase-like activity in a dog with congenital pulmonic stenosis.

PubMed

Fujii, Yoko; Yamane, Tsuyoshi; Orito, Kensuke; Osamura, Kaori; Wakao, Yoshito

2007-05-01

This study was intended to compare the tissue chymase-like activity and angiotensin converting enzyme (ACE) activity in the right and left ventricles of a dog with congenital pulmonic stenosis (PS), with normal dogs, and to discuss the potential clinical implications of these findings. Study subjects included a one-year-old Beagle dog with spontaneous PS and six clinically normal Beagles. Chymase-like and ACE activities were determined in all hearts by high pressure liquid chromatography. In the PS dog right ventricular (RV) chymase-like activity (49.79 nmol/min/g tissue) and left ventricular (LV) chymase-like activity (36.85 nmol/min/g tissue) were elevated vs normal Beagle dogs (mean+/-standard deviation, RV: 20.17+/-5.24 nmol/min/g, LV: 19.03+/-3.27 nmol/min/g). Activation of the tissue RAA system was detected in a dog with congenital PS. This interesting finding should be pursued with further studies to validate this result, and to explore whether pharmacological blockade of chymase, or the angiotensin II receptor, represents a useful strategy to prevent myocardial remodeling in this condition.

Novel Anaerobic Wastewater Treatment System for Energy Generation at Forward Operating Bases

DTIC Science & Technology

2016-08-01

AnMBR) technology with clinoptilolite ion exchange and GreenBox™ ammonia electrolysis. The system generates both methane and hydrogen fuels...experimental setup. ................................................ 21 Figure 10. Methane phase semi batch experimental setup, a total of three reactors were...set up for PS + solid, Bioc and ADS methane phase reactors. .................... 21 Figure 11. Dried PS solid for the control, Bioc blend for the

Ultrafast electric phase control of a single exciton qubit

NASA Astrophysics Data System (ADS)

Widhalm, Alex; Mukherjee, Amlan; Krehs, Sebastian; Sharma, Nandlal; Kölling, Peter; Thiede, Andreas; Reuter, Dirk; Förstner, Jens; Zrenner, Artur

2018-03-01

We report on the coherent phase manipulation of quantum dot excitons by electric means. For our experiments, we use a low capacitance single quantum dot photodiode which is electrically controlled by a custom designed SiGe:C BiCMOS chip. The phase manipulation is performed and quantified in a Ramsey experiment, where ultrafast transient detuning of the exciton energy is performed synchronous to double pulse π/2 ps laser excitation. We are able to demonstrate electrically controlled phase manipulations with magnitudes up to 3π within 100 ps which is below the dephasing time of the quantum dot exciton.

Formal integration of controlled-source and passive seismic data: Utilization of the CD-ROM experiment

NASA Astrophysics Data System (ADS)

Rumpfhuber, E.; Keller, G. R.; Velasco, A. A.

2005-12-01

Many large-scale experiments conduct both controlled-source and passive deployments to investigate the lithospheric structure of a targeted region. Many of these studies utilize each data set independently, resulting in different images of the Earth depending on the data set investigated. In general, formal integration of these data sets, such as joint inversions, with other data has not been performed. The CD-ROM experiment, which included both 2-D controlled-source and passive recording along a profile extending from southern Wyoming to northern New Mexico serves as an excellent data set to develop a formal integration strategy between both controlled source and passive experiments. These data are ideal to develop this strategy because: 1) the analysis of refraction/wide-angle reflection data yields Vp structure, and sometimes Vs structure, of the crust and uppermost mantle; 2) analysis of the PmP phase (Moho reflection) yields estimates of the average Vp of the crust for the crust; and 3) receiver functions contain full-crustal reverberations and yield the Vp/Vs ratio, but do not constrain the absolute P and S velocity. Thus, a simple form of integration involves using the Vp/Vs ratio from receiver functions and the average Vp from refraction measurements, to solve for the average Vs of the crust. When refraction/ wide-angle reflection data and several receiver functions nearby are available, an integrated 2-D model can be derived. In receiver functions, the PS conversion gives the S-wave travel-time (ts) through the crust along the raypath traveled from the Moho to the surface. Since the receiver function crustal reverberation gives the Vp/Vs ratio, it is also possible to use the arrival time of the converted phase, PS, to solve for the travel time of the direct teleseismic P-wave through the crust along the ray path. Raytracing can yield the point where the teleseismic wave intersects the Moho. In this approach, the conversion point is essentially a pseudo-shotpoint, thus the converted arrival at the surface can be jointly modeled with refraction data using a 3-D inversion code. Employing the combined CD-ROM data sets, we will be investigating the joint inversion results of controlled source data and receiver functions.

Free-running waveform characterization using a delay-time tunable laser based delay-line-free electro-optic sampling oscilloscope

NASA Astrophysics Data System (ADS)

Lin, Gong-Ru

2002-12-01

We develop a delay-line-free and frequency traceable electro-optic sampling oscilloscope by use of a digital phase-locked loop phase shifter (PLL-PS) controlled delay-time-tunable gain-switched laser diode (GSLD). The home-made voltage-controllable PLL-PS exhibits a linear transfer function with ultra-wide phase shifting range of ±350° and tuning error of <±5%, which benefits the advantages of frequency tracking to free-running signals with suppressed timing-jitter. The maximum delay-time of PLL-PS controlled GSLD is up to 1.95 periods by changing the controlling voltage ( VREF) from -3.5 to 3.5 V, which corresponds to 3.9 ns at repetition frequency of 500 MHz. The tuning responsivity and resolution are about 0.56 ns/V and 0.15˜0.2 ps, respectively. The maximum delay-time switching bandwidth of 100 Hz is determined under the control of a saw-tooth modulated VREF function. The waveform sampling of microwave PECL signals generated from a free-running digital frequency divider is performed with acceptable measuring deviation.

Phase behavior of diblock copolymer/star-shaped polymer thin film mixtures.

PubMed

Zhao, Junnan; Sakellariou, Georgios; Green, Peter F

2016-05-07

We investigated the phase behavior of thin film, thickness h≈ 100 nm, mixtures of a polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymer with star-shaped polystyrene (SPS) molecules of varying functionalities f, where 4 ≤f≤ 64, and molecular weights per arm Marm. The miscibility of the system and the surface composition varied appreciably with Marm and f. For large values of Marm, regardless of f, the miscibility of the system was qualitatively similar to that of linear chain PS/PS-b-P2VP mixtures - the copolymer chains aggregate to form micelles, each composed of an inner P2VP core and PS corona, which preferentially segregate to the free surface. On the other hand, for large f and small Marm, SPS molecules preferentially resided at the free surface. Moreover, blends containing SPS molecules with the highest values of f and lowest values of Marm were phase separated. These observations are rationalized in terms of competing entropic interactions and the dependence of the surface tension of the star-shaped molecules on Marm and f.

Separation of Poly(styrene-block-t-butyl methacrylate) Copolymers by Various Liquid Chromatography Techniques

PubMed Central

Šmigovec Ljubič, Tina; Pahovnik, David; Žigon, Majda; Žagar, Ema

2012-01-01

The separation of a mixture of three poly(styrene-block-t-butyl methacrylate) copolymers (PS-b-PtBMA), consisting of polystyrene (PS) blocks of similar length and t-butyl methacrylate (PtBMA) blocks of different lengths, was performed using various chromatographic techniques, that is, a gradient liquid chromatography on reversed-phase (C18 and C8) and normal-phase columns, a liquid chromatography under critical conditions for polystyrene as well as a fully automated two-dimensional liquid chromatography that separates block copolymers by chemical composition in the first dimension and by molar mass in the second dimension. The results show that a partial separation of the mixture of PS-b-PtBMA copolymers can be achieved only by gradient liquid chromatography on reversed-phase columns. The coelution of the two block copolymers is ascribed to a much shorter PtBMA block length, compared to the PS block, as well as a small difference in the length of the PtBMA block in two of these copolymers, which was confirmed by SEC-MALS and NMR spectroscopy. PMID:22489207

Functional magnetic resonance imaging phase synchronization as a measure of dynamic functional connectivity.

PubMed

Glerean, Enrico; Salmi, Juha; Lahnakoski, Juha M; Jääskeläinen, Iiro P; Sams, Mikko

2012-01-01

Functional brain activity and connectivity have been studied by calculating intersubject and seed-based correlations of hemodynamic data acquired with functional magnetic resonance imaging (fMRI). To inspect temporal dynamics, these correlation measures have been calculated over sliding time windows with necessary restrictions on the length of the temporal window that compromises the temporal resolution. Here, we show that it is possible to increase temporal resolution by using instantaneous phase synchronization (PS) as a measure of dynamic (time-varying) functional connectivity. We applied PS on an fMRI dataset obtained while 12 healthy volunteers watched a feature film. Narrow frequency band (0.04-0.07 Hz) was used in the PS analysis to avoid artifactual results. We defined three metrics for computing time-varying functional connectivity and time-varying intersubject reliability based on estimation of instantaneous PS across the subjects: (1) seed-based PS, (2) intersubject PS, and (3) intersubject seed-based PS. Our findings show that these PS-based metrics yield results consistent with both seed-based correlation and intersubject correlation methods when inspected over the whole time series, but provide an important advantage of maximal single-TR temporal resolution. These metrics can be applied both in studies with complex naturalistic stimuli (e.g., watching a movie or listening to music in the MRI scanner) and more controlled (e.g., event-related or blocked design) paradigms. A MATLAB toolbox FUNPSY ( http://becs.aalto.fi/bml/software.html ) is openly available for using these metrics in fMRI data analysis.

Conversion of partially reprogrammed cells to fully pluripotent stem cells is associated with further activation of stem cell maintenance- and gamete generation-related genes.

PubMed

Kim, Jong Soo; Choi, Hyun Woo; Choi, Sol; Seo, Han Geuk; Moon, Sung-Hwan; Chung, Hyung-Min; Do, Jeong Tae

2014-11-01

Somatic cells are reprogrammed to induced pluripotent stem cells (iPSCs) by overexpression of a combination of defined transcription factors. We generated iPSCs from mouse embryonic fibroblasts (with Oct4-GFP reporter) by transfection of pCX-OSK-2A (Oct4, Sox2, and Klf4) and pCX-cMyc vectors. We could generate partially reprogrammed cells (XiPS-7), which maintained more than 20 passages in a partially reprogrammed state; the cells expressed Nanog but were Oct4-GFP negative. When the cells were transferred to serum-free medium (with serum replacement and basic fibroblast growth factor), the XiPS-7 cells converted to Oct4-GFP-positive iPSCs (XiPS-7c, fully reprogrammed cells) with ESC-like properties. During the conversion of XiPS-7 to XiPS-7c, we found several clusters of slowly reprogrammed genes, which were activated at later stages of reprogramming. Our results suggest that partial reprogrammed cells can be induced to full reprogramming status by serum-free medium, in which stem cell maintenance- and gamete generation-related genes were upregulated. These long-term expandable partially reprogrammed cells can be used to verify the mechanism of reprogramming.

Acyl Chain Preference in Foam Cell Formation from Mouse Peritoneal Macrophages.

PubMed

Fujiwara, Yuko; Hama, Kotaro; Tsukahara, Makoto; Izumi-Tsuzuki, Ryosuke; Nagai, Toru; Ohe-Yamada, Mihoko; Inoue, Keizo; Yokoyama, Kazuaki

2018-01-01

Macrophage foam cells play critical roles in the initiation and development of atherosclerosis by synthesizing and accumulating cholesteryl ester (CE) in lipid droplets. However, in analyzing lipid metabolism in foam cell formation, studies have focused on the sterol group, and little research has been done on the acyl chains. Therefore, we adapted a model system using liposomes containing particular acyl chains and examined the effect of various acyl chains on foam cell formation. Of the phosphatidylserine (PS) liposomes tested containing PS, phosphatidylcholine, and cholesterol, we found that unsaturated (C18:1), but not saturated (C16:0 and C18:0), PS liposomes induced lipid droplet formation, indicating that foam cell formation depends on the nature of the acyl chain of the PS liposomes. Experiments on the uptake and accumulation of cholesterol from liposomes by adding [ 14 C]cholesterol suggested that foam cell formation could be induced only when cholesterol was converted to CE in the case of C18:1 PS liposomes. Both microscopic observations and metabolic analysis suggest that cholesterol incorporated into either C16:0 or C18:0 PS liposomes may stay intact after being taken in by endosomes. The [ 14 C]C18:1 fatty acyl chain in the C18:1 PS liposome was used to synthesize CE and triacylglycerol (TG). Interestingly, the [ 14 C]C16:0 in the C18:1 PS liposome was metabolized to sphingomyelin rather than being incorporated into either CE or TG, which could be because of enzymatic acyl chain selectivity. In conclusion, our results indicate that the acyl chain preference of macrophages could have some impact on their progression to foam cells.

A 3.9 ps Time-Interval RMS Precision Time-to-Digital Converter Using a Dual-Sampling Method in an UltraScale FPGA

NASA Astrophysics Data System (ADS)

Wang, Yonggang; Liu, Chong

2016-10-01

Field programmable gate arrays (FPGAs) manufactured with more advanced processing technology have faster carry chains and smaller delay elements, which are favorable for the design of tapped delay line (TDL)-style time-to-digital converters (TDCs) in FPGA. However, new challenges are posed in using them to implement TDCs with a high time precision. In this paper, we propose a bin realignment method and a dual-sampling method for TDC implementation in a Xilinx UltraScale FPGA. The former realigns the disordered time delay taps so that the TDC precision can approach the limit of its delay granularity, while the latter doubles the number of taps in the delay line so that the TDC precision beyond the cell delay limitation can be expected. Two TDC channels were implemented in a Kintex UltraScale FPGA, and the effectiveness of the new methods was evaluated. For fixed time intervals in the range from 0 to 440 ns, the average RMS precision measured by the two TDC channels reaches 5.8 ps using the bin realignment, and it further improves to 3.9 ps by using the dual-sampling method. The time precision has a 5.6% variation in the measured temperature range. Every part of the TDC, including dual-sampling, encoding, and on-line calibration, could run at a 500 MHz clock frequency. The system measurement dead time is only 4 ns.

Dual-domain lateral shearing interferometer

DOEpatents

Naulleau, Patrick P.; Goldberg, Kenneth Alan

2004-03-16

The phase-shifting point diffraction interferometer (PS/PDI) was developed to address the problem of at-wavelength metrology of extreme ultraviolet (EUV) optical systems. Although extremely accurate, the fact that the PS/PDI is limited to use with coherent EUV sources, such as undulator radiation, is a drawback for its widespread use. An alternative to the PS/PDI, with relaxed coherence requirements, is lateral shearing interferometry (LSI). The use of a cross-grating, carrier-frequency configuration to characterize a large-field 4.times.-reduction EUV lithography optic is demonstrated. The results obtained are directly compared with PS/PDI measurements. A defocused implementation of the lateral shearing interferometer in which an image-plane filter allows both phase-shifting and Fourier wavefront recovery. The two wavefront recovery methods can be combined in a dual-domain technique providing suppression of noise added by self-interference of high-frequency components in the test-optic wavefront.

Pump-probe STM light emission spectroscopy for detection of photo-induced semiconductor-metal phase transition of VO2

NASA Astrophysics Data System (ADS)

Sakai, Joe; Katano, Satoshi; Kuwahara, Masashi; Uehara, Yoichi

2017-10-01

We attempted to observe pump-probe scanning tunneling microscopy (STM)-light emission (LE) from a VO2 thin film grown on a rutile TiO2(0 0 1) substrate, with an Ag tip fixed over a semiconducting domain. Laser pulses from a Ti:sapphire laser (wavelength 920 nm pulse width less than 1.5 ps) irradiated the tip-sample gap as pump and probe light sources. With a photon energy of 2.7 eV, suggesting phase transition from semiconducting monoclinic (M) to metallic rutile (R) phases in relation to the electronic band structure, faint LE was observed roughly 30 ps after the irradiation of the pump pulse, followed by retention for roughly 20 ps. The incident energy fluence of the pump pulse at the gap was five orders of magnitude lower than the threshold value for reported photo-induced M-R phase transition. The mechanism that makes it possible to reduce the threshold fluence is discussed.

Pump-probe STM light emission spectroscopy for detection of photo-induced semiconductor-metal phase transition of VO2.

PubMed

Sakai, Joe; Katano, Satoshi; Kuwahara, Masashi; Uehara, Yoichi

2017-10-11

We attempted to observe pump-probe scanning tunneling microscopy (STM)-light emission (LE) from a VO 2 thin film grown on a rutile TiO 2 (0 0 1) substrate, with an Ag tip fixed over a semiconducting domain. Laser pulses from a Ti:sapphire laser (wavelength 920 nm; pulse width less than 1.5 ps) irradiated the tip-sample gap as pump and probe light sources. With a photon energy of 2.7 eV, suggesting phase transition from semiconducting monoclinic (M) to metallic rutile (R) phases in relation to the electronic band structure, faint LE was observed roughly 30 ps after the irradiation of the pump pulse, followed by retention for roughly 20 ps. The incident energy fluence of the pump pulse at the gap was five orders of magnitude lower than the threshold value for reported photo-induced M-R phase transition. The mechanism that makes it possible to reduce the threshold fluence is discussed.

Identification of a novel phospholipase D with high transphosphatidylation activity and its application in synthesis of phosphatidylserine and DHA-phosphatidylserine.

PubMed

Mao, Xiangzhao; Liu, Qianqian; Qiu, Yongqian; Fan, Xiaoqin; Han, Qingqing; Liu, Yanjun; Zhang, Lujia; Xue, Changhu

2017-05-10

Phosphatidylserine (PS) and docosahexaenoic acid-phosphatidylserine (DHA-PS) have significant nutritional and biological functions, which are extensively used in functional food industries. Phospholipase D (PLD)-mediated transphosphatidylation of phosphatidylcholine (PC) or DHA-PC with l-serine, is an effective method for PS and DHA-PS preparation. However, because of the hydrolysis activity of PLD, PC and DHA-PC would be converted to the undesirable byproduct, phosphatidic acid (PA) and DHA-PA. In this study, a novel phospholipase D (PLD a2 ) was firstly cloned from Acinetobacter radioresistens a2 with high transphosphatidylation activity and no hydrolysis activity. In the PLD-catalyzed synthesis process (12h), both the transphosphatidylation conversion rate and selectivity of PS and DHA-PS were about 100%, which is the only PLD enzyme reported with this superiority up till now. In comparison with the majority of other known PLDs, PLD a2 exerted the highest activity at neutral pH, and it was stable from pH 4.0 to pH 9.0. In addition, PLD a2 had excellent thermal stability, with an optimum reaction temperature of 40°C and keeping more than 80% activity from 20°C to 60°C. The high catalytic selectivity mechanism of PLD a2 was explained by utilizing homology modeling, two-step docking, and binding energy and conformation analysis. PLD a2 ensured a stable supply of the biocatalyst with its most preponderant transphosphatidylation activity and PS selectivity, and had great potential in phospholipids industrial production. Copyright © 2017 Elsevier B.V. All rights reserved.

On-chip programmable ultra-wideband microwave photonic phase shifter and true time delay unit.

PubMed

Burla, Maurizio; Cortés, Luis Romero; Li, Ming; Wang, Xu; Chrostowski, Lukas; Azaña, José

2014-11-01

We proposed and experimentally demonstrated an ultra-broadband on-chip microwave photonic processor that can operate both as RF phase shifter (PS) and true-time-delay (TTD) line, with continuous tuning. The processor is based on a silicon dual-phase-shifted waveguide Bragg grating (DPS-WBG) realized with a CMOS compatible process. We experimentally demonstrated the generation of delay up to 19.4 ps over 10 GHz instantaneous bandwidth and a phase shift of approximately 160° over the bandwidth 22-29 GHz. The available RF measurement setup ultimately limits the phase shifting demonstration as the device is capable of providing up to 300° phase shift for RF frequencies over a record bandwidth approaching 1 THz.

Diblock copolymers of polystyrene- b-poly(1,3-cyclohexadiene) exhibiting unique three-phase microdomain morphologies

DOE PAGES

Misichronis, Konstantinos; Chen, Jihua; Kahk, Jong K.; ...

2016-03-29

Here, the synthesis and molecular characterization of a series of conformationally asymmetric polystyrene-block-poly(1,3-cyclohexadiene) (PS- b-PCHD) diblock copolymers (PCHD: ~90% 1,4 and ~10% 1,2), by sequential anionic copolymerization high vacuum techniques, is reported. A wide range of volume fractions (0.27 ≤ Φ PS ≤ 0.91) was studied by transmission electron microscopy and small-angle X-ray scattering in order to explore in detail the microphase separation behavior of these flexible/semiflexible diblock copolymers. Unusual morphologies, consisting of PCHD core(PCHD-1,4)–shell(PCHD-1,2) cylinders in PS matrix and three-phase (PS, PCHD-1,4, PCHD-1,2) four-layer lamellae, were observed suggesting that the chain stiffness of the PCHD block and the strongmore » dependence of the interaction parameter χ on the PCHD microstructures are important factors for the formation of this unusual microphase separation behavior in PS- b-PCHD diblock copolymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1564–1572« less

Crystallization and Microphase Separation in Chiral Block Copolymers

NASA Astrophysics Data System (ADS)

Ho, Rong-Ming

2012-02-01

Block copolymers composed of chiral entities, denoted as chiral block copolymers (BCP*s), were designed to fabricate helical architectures from self-assembly. A helical phase (denoted H*) was discovered in the self-assembly of poly(styrene)-b-poly(L-lactide) (PS-PLLA) BCPs*. To examine the phase behavior of the PS-PLLA, self-assembled superstructures resulting from the competition between crystallization and microphase separation of the PS-PLLA in solution were examined. A kinetically controlled process by changing non-solvent addition rate was utilized to control the BCP* self-assembly. Single-crystal lozenge lamellae were obtained by the slow self-assembly (i.e., slow non-solvent addition rate) of PS-PLLA whereas amorphous helical ribbon superstructures were obtained from the fast self-assembly (i.e., fast non-solvent addition rate). As a result, the formation of helical architectures from the self-assembly of the PS-PLLA reflects the impact of chirality on microphase separation, but the chiral effect might be overwhelmed by crystallization. Consequently, various crystalline PS-PLLA nanostructures in bulk were obtained by controlling the crystallization temperature of PLLA (Tc,PLLA) at which crystalline helices and crystalline cylinders occur while Tc,PLLA=x Tg,PS, respectively. Anisotropic arrangement of the PLLA crystallites grown within the microdomains was identified. The formation of this exclusive crystalline growth is attributed to the spatial confinement effect for crystallization. While Tc,PLLA=x Tg,PS, the preferential growth may modulate the curvature of microdomains by shifting the molecular chains to access the fast path for crystalline growth due to the increase in chain mobility. As a result, a spring-like behavior of the helical nanostructure can be driven by crystallization so as to dictate the transformation of helices and to result in crystalline cylinders.

Investigation in clinical potential of polarization sensitive optical coherence tomography in laryngeal tumor model study

NASA Astrophysics Data System (ADS)

Zhou, Xin; Oak, Chulho; Ahn, Yeh-Chan; Kim, Sung Won; Tang, Shuo

2018-02-01

Polarization-sensitive optical coherence tomography (PS-OCT) is capable of measuring tissue birefringence. It has been widely applied to access the birefringence in tissues such as skin and cartilage. The vocal cord tissue consists of three anatomical layers from the surface to deep inside, the epithelium that contains almost no collagen, the lamina propria that is composed with abundant collagen, and the vocalis muscle layer. Due to the variation in the organization of collagen fibers, the different tissue layers show different tissue birefringence, which can be evaluated by PS-OCT phase retardation measurement. Furthermore, collagen fibers in healthy connective tissues are usually well organized, which provides relatively high birefringence. When the collagen organization is destroyed by diseases such as tumor, the birefringence of the tissue will decrease. In this study, a rabbit laryngeal tumor model with different stages of tumor progression is investigated ex-vivo by PS-OCT. The PS-OCT images show a gradual decrease in birefringence from normal tissue to severe tumor tissue. A phase retardation slope-based analysis is conducted to distinguish the epithelium, lamina propria, and muscle layers, respectively. The phase retardation slope quantifies the birefringence in different layers. The quantitative study provides a more detailed comparison among different stages of the rabbit laryngeal tumor model. The PS-OCT result is validated by the corresponding histology images of the same samples.

A 45 ps time digitizer with a two-phase clock and dual-edge two-stage interpolation in a field programmable gate array device

NASA Astrophysics Data System (ADS)

Szplet, R.; Kalisz, J.; Jachna, Z.

2009-02-01

We present a time digitizer having 45 ps resolution, integrated in a field programmable gate array (FPGA) device. The time interval measurement is based on the two-stage interpolation method. A dual-edge two-phase interpolator is driven by the on-chip synthesized 250 MHz clock with precise phase adjustment. An improved dual-edge double synchronizer was developed to control the main counter. The nonlinearity of the digitizer's transfer characteristic is identified and utilized by the dedicated hardware code processor for the on-the-fly correction of the output data. Application of presented ideas has resulted in the measurement uncertainty of the digitizer below 70 ps RMS over the time interval ranging from 0 to 1 s. The use of the two-stage interpolation and a fast FIFO memory has allowed us to obtain the maximum measurement rate of five million measurements per second.

Intramolecular vibrational energy redistribution and intermolecular energy transfer of benzene in supercritical CO 2: measurements from the gas phase up to liquid densities

NASA Astrophysics Data System (ADS)

von Benten, R.; Charvat, A.; Link, O.; Abel, B.; Schwarzer, D.

2004-03-01

Femtosecond pump probe spectroscopy was employed to measure intramolecular vibrational energy redistribution (IVR) and intermolecular vibrational energy transfer (VET) of benzene in the gas phase and in supercritical (sc) CO 2. We observe two IVR time scales the faster of which proceeds within τ IVR(1)<0.5 ps. The slower IVR component has a time constant of τ IVR(2)=(48±5) ps in the gas phase and in scCO 2 is accelerated by interactions with the solvent. At the highest CO 2 density it is reduced to τ IVR(2)=(6±1) ps. The corresponding IVR rate constants show a similar density dependence as the VET rate constants. Model calculations suggest that both quantities correlate with the local CO 2 density in the immediate surrounding of the benzene molecule.

Silencing trehalose-6-phosphate synthase incapacitates adult mosquitoes by interfering with the biosynthetic pathway for flight fuel

USDA-ARS?s Scientific Manuscript database

Trehalose is a disaccharide comprised of two glucose molecules. It is the main blood sugar of insects and is essential for flight. Trehalose is synthesized by two enzymes: trehalose-6-phosphate synthase (T6PS) converts glucose-6-phosphate to trehalose-6-phosphate, and trehalose-6-phosphate phosphata...

Cheaper Synthesis Of Multipole-Brushless-dc-Motor Current

NASA Technical Reports Server (NTRS)

Alhorn, Dean C.; Howard, David E.

1994-01-01

Circuit converts output of single two-phase shaft-angle resolver to that of multi-speed three-phase shaft-angle resolver. Converter circuit applicable to generation of multispeed, multiphase shaft-angle-resolver signals from single two-phase shaft-angle resolver. Combination of converter circuit and single two-phase shaft-angle resolver offer advantages in cost, weight, size, and complexity. Design readily adaptable to two-phase motor.

Tapping in synchrony with a perturbed metronome: the phase correction response to small and large phase shifts as a function of tempo.

PubMed

Repp, Bruno H

2011-01-01

When tapping is paced by an auditory sequence containing small phase shift (PS) perturbations, the phase correction response (PCR) of the tap following a PS increases with the baseline interonset interval (IOI), leading eventually to overcorrection (B. H. Repp, 2008). Experiment 1 shows that this holds even for fixed-size PSs that become imperceptible as the IOI increases (here, from 400 to 1200 ms). Earlier research has also shown (but only for IOI=500 ms) that the PCR is proportionally smaller for large than for small PSs (B. H. Repp, 2002a, 2002b). Experiment 2 introduced large PSs and found smaller PCRs than in Experiment 1, at all of the same IOIs. In Experiments 3A and 3B, the author investigated whether the change in slope of the sigmoid function relating PCR and PS magnitudes occurs at a fixed absolute or relative PS magnitude across different IOIs (600, 1000, 1400 ms). The results suggest no clear answer; the exact shape of the function may depend on the range of PSs used in an experiment. Experiment 4 examined the PCR in the IOI range from 1000 to 2000 ms and found overcorrection throughout, but with the PCR increasing much more gradually than in Experiment 1. These results provide important new information about the phase correction process and pose challenges for models of sensorimotor synchronization, which presently cannot explain nonlinear PCR functions and overcorrection. Copyright © Taylor & Francis Group, LLC

The effect of PS porosity on the structure, optical and electrical properties of ZnS/PS

NASA Astrophysics Data System (ADS)

Wang, Cai-Feng; Hu, Bo; Yi, Hou-Hui; Li, Wei-Bing

2014-03-01

ZnS films were deposited on porous silicon (PS) substrates with different porosities by pulsed laser deposition (PLD). The crystalline structure, surface morphology of ZnS films on PS substrates and optical, electrical properties of ZnS/PS composites were studied. The results show that, ZnS films deposited on PS substrates were grown in preferred orientation along β-ZnS (111) direction corresponding to crystalline structure of cubic phase. With the increase of PS porosity, the XRD diffraction peak intensity of ZnS films decreases. Some voids and cracks appear in the films. Compared with as-prepared PS, the PL peak of PS for ZnS/PS has a blueshift. The larger the porosity of PS, the greater the blueshift is. A new green light emission located around 550 nm is observed with increasing PS porosity, which is ascribed to defect-center luminescence of ZnS. The blue, green emission of ZnS combined with the red emission of PS, a broad photoluminescence band (450-750 nm) is formed. ZnS/PS composites exhibited intense white light emission. The I-V characteristics of ZnS/PS heterojunctions showed rectifying behavior. Under forward bias conditions, the current density is large. Under reverse bias conditions, the current density nearly to be zero. The forward current increases with increasing PS porosity. This work lay a foundation for the realization of electroluminescence of ZnS/PS and solid white light emission devices.

Thermodynamics of coil-hyperbranched poly(styrene-b-acrylated epoxidized soybean oil) block copolymers

NASA Astrophysics Data System (ADS)

Lin, Fang-Yi; Hohmann, Austin; Hernández, Nacú; Cochran, Eric

Here we present the phase behavior of a new type of coil-hyperbranched diblock copolymer: poly(styrene- b-acrylated epoxidized soybean oil), or PS-PAESO. PS-PAESO is an example of a biorenewable thermoplastic elastomer (bio-TPE). To date, we have shown that bio-TPEs can be economical commercial substitutes for their petrochemically derived analogues--such as poly(styrene- b-butadiene- b-styrene) (SBS)--in a range of applications including pressure sensitive adhesives and bitumen modification. From a polymer physics perspective, PS-PAESO is an interesting material in that it couples a linear coil-like block with a highly branched block. Thus in contrast to the past five decades of studies on linear AB diblock copolymers, coil-hyperbranched block copolymers are relatively unknown to the community and can be expected to deviate substantially from the standard ``universal'' phase behavior in the AB systems. To explore these new materials, we have constructed a library of PS-PAESO materials spanning a range of molecular weight and composition values. The phase transition behavior and the morphology information will be interpreted by isochronal temperature scanning in dynamic shear rheology, small angle X-ray scattering and the corresponding transmission electron microscopy.

Ultra-fast switching blue phase liquid crystals diffraction grating stabilized by chiral monomer

NASA Astrophysics Data System (ADS)

Manda, Ramesh; Pagidi, Srinivas; Sarathi Bhattacharya, Surjya; Yoo, Hyesun; T, Arun Kumar; Lim, Young Jin; Lee, Seung Hee

2018-05-01

We have demonstrated an ultra-fast switching and efficient polymer stabilized blue phase liquid crystal (PS-BPLC) diffraction grating utilizing a chiral monomer. We have obtained a 0.5 ms response time by a novel polymer stabilization method which is three times faster than conventional PS-BPLC. In addition, the diffraction efficiency was improved 2% with a much wider phase range and the driving voltage to switch the device is reduced. The polarization properties of the diffracted beam are unaffected by this novel polymer stabilization. This device can be useful for future photonic applications.

Substrats poreux biodegradables prepares a partir de phases co-continues dans les melanges de polymeres immiscibles

NASA Astrophysics Data System (ADS)

Sarazin, Pierre

2003-06-01

In this thesis a novel approach to preparing biodegradable materials with highly structured and interconnected porosity is proposed. The method involves the controlled preparation of immiscible co-continuous polymer blends using melt-processing technology followed by a bulk solvent extraction step of one of the phases (the porogen phase). A co-continuous structure is defined as the state when each phase of the blend is fully interconnected through a continuous pathway. This method allows for the preparation of porous materials with highly controlled pore size, pore volume and pore shape which can then be transformed and shaped in various forms useful for biomedical applications. Various properties of the skin of the polymeric articles (closed-cell, open-cell, modification of the pore size) can be controlled. Initially, the study on the immiscible binary and compatibilized poly(L-lactide)/polystyrene blends (PLLA/PS) after extraction of the PS phase demonstrated that highly percolated blends exist from 40--75%PS and 40--60%PS for the binary and compatibilized blends, respectively. It is demonstrated that both the pore size and extent of co-continuity can be controlled through composition and interfacial modification. The subsequent part of our work treats of the preparation of porous PLLA from a blend of two biodegradable polymers and the performance of such porous materials. This portion of the work uses only polymer materials which have been medically approved for internal use. In this case, small amounts of the porogen phase can be tolerated in the final porous substrate. Co-continuous blends comprised of poly(L-lactide)/Poly(epsilon-caprolactone) PLLA/PCL, were prepared via melt processing. A wide range of phase sizes for the co-continuous blend is generated through a combination of concentration control and quiescent annealing. As the PLLA phase can not be dissolved selectively in PLLA/PS blends, the co-continuity range was evaluated indirectly. To precisely assess the formation of the co-continuous morphology, the polylactide was replaced by a poly(epsilon-caprolactone) (PCL) in the following work. PCL possesses a similar biocompatibility, although it exhibits a much slower degradation rate. These results practically allow for a separation of the effects of deformation/disintegration processes and coalescence on continuous and co-continuous morphology development. Coalescence phenomena for systems such as the PS in PCL case is clearly the dominant parameter controlling phase size at higher compositions. These results underline the requirement of co-continuity models to include parameters related to coalescence effects. The data indicate the significant potential of mixing temperature as a tool for the morphology control of co-continuous polymer blends. (Abstract shortened by UMI.)

Near-infrared image-guided laser ablation of dental decay

NASA Astrophysics Data System (ADS)

Tao, You-Chen; Fried, Daniel

2009-09-01

Image-guided laser ablation systems are now feasible for dentistry with the recent development of nondestructive high-contrast imaging modalities such as near-IR (NIR) imaging and optical coherence tomography (OCT) that are capable of discriminating between sound and demineralized dental enamel at the early stages of development. Our objective is to demonstrate that images of demineralized tooth surfaces have sufficient contrast to be used to guide a CO2 laser for the selective removal of natural and artificial caries lesions. NIR imaging and polarization-sensitive optical coherence tomography (PS-OCT) operating at 1310-nm are used to acquire images of natural lesions on extracted human teeth and highly patterned artificial lesions produced on bovine enamel. NIR and PS-OCT images are analyzed and converted to binary maps designating the areas on the samples to be removed by a CO2 laser to selectively remove the lesions. Postablation NIR and PS-OCT images confirmed preferential removal of demineralized areas with minimal damage to sound enamel areas. These promising results suggest that NIR and PS-OCT imaging systems can be integrated with a CO2 laser ablation system for the selective removal of dental caries.

Near-infrared image-guided laser ablation of dental decay

PubMed Central

Tao, You-Chen; Fried, Daniel

2009-01-01

Image-guided laser ablation systems are now feasible for dentistry with the recent development of nondestructive high-contrast imaging modalities such as near-IR (NIR) imaging and optical coherence tomography (OCT) that are capable of discriminating between sound and demineralized dental enamel at the early stages of development. Our objective is to demonstrate that images of demineralized tooth surfaces have sufficient contrast to be used to guide a CO2 laser for the selective removal of natural and artificial caries lesions. NIR imaging and polarization-sensitive optical coherence tomography (PS-OCT) operating at 1310-nm are used to acquire images of natural lesions on extracted human teeth and highly patterned artificial lesions produced on bovine enamel. NIR and PS-OCT images are analyzed and converted to binary maps designating the areas on the samples to be removed by a CO2 laser to selectively remove the lesions. Postablation NIR and PS-OCT images confirmed preferential removal of demineralized areas with minimal damage to sound enamel areas. These promising results suggest that NIR and PS-OCT imaging systems can be integrated with a CO2 laser ablation system for the selective removal of dental caries. PMID:19895146

Near-infrared image-guided laser ablation of dental decay.

PubMed

Tao, You-Chen; Fried, Daniel

2009-01-01

Image-guided laser ablation systems are now feasible for dentistry with the recent development of nondestructive high-contrast imaging modalities such as near-IR (NIR) imaging and optical coherence tomography (OCT) that are capable of discriminating between sound and demineralized dental enamel at the early stages of development. Our objective is to demonstrate that images of demineralized tooth surfaces have sufficient contrast to be used to guide a CO(2) laser for the selective removal of natural and artificial caries lesions. NIR imaging and polarization-sensitive optical coherence tomography (PS-OCT) operating at 1310-nm are used to acquire images of natural lesions on extracted human teeth and highly patterned artificial lesions produced on bovine enamel. NIR and PS-OCT images are analyzed and converted to binary maps designating the areas on the samples to be removed by a CO(2) laser to selectively remove the lesions. Postablation NIR and PS-OCT images confirmed preferential removal of demineralized areas with minimal damage to sound enamel areas. These promising results suggest that NIR and PS-OCT imaging systems can be integrated with a CO(2) laser ablation system for the selective removal of dental caries.

High-speed polarization sensitive optical coherence tomography for retinal diagnostics

NASA Astrophysics Data System (ADS)

Yin, Biwei; Wang, Bingqing; Vemishetty, Kalyanramu; Nagle, Jim; Liu, Shuang; Wang, Tianyi; Rylander, Henry G., III; Milner, Thomas E.

2012-01-01

We report design and construction of an FPGA-based high-speed swept-source polarization-sensitive optical coherence tomography (SS-PS-OCT) system for clinical retinal imaging. Clinical application of the SS-PS-OCT system is accurate measurement and display of thickness, phase retardation and birefringence maps of the retinal nerve fiber layer (RNFL) in human subjects for early detection of glaucoma. The FPGA-based SS-PS-OCT system provides three incident polarization states on the eye and uses a bulk-optic polarization sensitive balanced detection module to record two orthogonal interference fringe signals. Interference fringe signals and relative phase retardation between two orthogonal polarization states are used to obtain Stokes vectors of light returning from each RNFL depth. We implement a Levenberg-Marquardt algorithm on a Field Programmable Gate Array (FPGA) to compute accurate phase retardation and birefringence maps. For each retinal scan, a three-state Levenberg-Marquardt nonlinear algorithm is applied to 360 clusters each consisting of 100 A-scans to determine accurate maps of phase retardation and birefringence in less than 1 second after patient measurement allowing real-time clinical imaging-a speedup of more than 300 times over previous implementations. We report application of the FPGA-based SS-PS-OCT system for real-time clinical imaging of patients enrolled in a clinical study at the Eye Institute of Austin and Duke Eye Center.

Morphological Evolution of Gyroid-Forming Block Copolymer Thin Films with Varying Solvent Evaporation Rate.

PubMed

Wu, Yi-Hsiu; Lo, Ting-Ya; She, Ming-Shiuan; Ho, Rong-Ming

2015-08-05

In this study, we aim to examine the morphological evolution of block copolymer (BCP) nanostructured thin films through solvent evaporation at different rates for solvent swollen polystyrene-block-poly(l-lactide) (PS-PLLA). Interesting phase transitions from disorder to perpendicular cylinder and then gyroid can be found while using a partially selective solvent for PS to swell PS-PLLA thin film followed by solvent evaporation. During the transitions, gyroid-forming BCP thin film with characteristic crystallographic planes of (111)G, (110)G, and (211)G parallel to air surface can be observed, and will gradually transform into coexisting (110)G and (211)G planes, and finally transforms to (211)G plane due to the preferential segregation of constituted block to the surface (i.e., the thermodynamic origin for self-assembly) that affects the relative amount of each component at the air surface. With the decrease on the evaporation rate, the disorder phase will transform to parallel cylinder and then directly to (211)G without transition to perpendicular cylinder phase. Most importantly, the morphological evolution of PS-PLLA thin films is strongly dependent upon the solvent removal rate only in the initial stage of the evaporation process due to the anisotropy of cylinder structure. Once the morphology is transformed back to the isotropic gyroid structure after long evaporation, the morphological evolution will only relate to the variation of the surface composition. Similar phase transitions at the substrate can also be obtained by controlling the ratio of PLLA-OH to PS-OH homopolymers to functionalize the substrate. As a result, the fabrication of well-defined nanostructured thin films with controlled orientation can be achieved by simple swelling and deswelling with controlled evaporation rate.

Polysulfide Binding to Several Nanoscale Magnéli Phases Synthesized in Carbon for Long-Life Lithium-Sulfur Battery Cathodes.

PubMed

Zubair, Usman; Amici, Julia; Francia, Carlotta; McNulty, David; Bodoardo, Silvia; O'Dwyer, Colm

2018-06-11

In Li-S batteries, it is important to ensure efficient reversible conversion of sulfur to lithium polysulfide (LiPS). Shuttling effects caused by LiPS dissolution can lead to reduced performance and cycle life. Although carbon materials rely on physical trapping of polysulfides, polar oxide surfaces can chemically bind LiPS to improve the stability of sulfur cathodes. We show a simple synthetic method that allows high sulfur loading into mesoporous carbon preloaded with spatially localized nanoparticles of several Magnéli-phase titanium oxide (Ti n O 2n-1 ). This material simultaneously suppresses polysulfide shuttling phenomena by chemically binding Li polysulfides onto several Magnéli-phase surfaces in a single cathode and ensures physical confinement of sulfur and LiPS. The synergy between chemical immobilization of significant quantities of LiPS at the surface of several Ti n O 2n-1 phases and physical entrapment results in coulombically efficient high-rate cathodes with long cycle life and high capacity. These cathodes function efficiently at low electrolyte-to-sulfur ratios to provide high gravimetric and volumetric capacities in comparison with their highly porous carbon counterparts. Assembled coin cells have an initial discharge capacity of 1100 mAh g -1 at 0.1C and maintain a reversible capacity of 520 mAh g -1 at 0.2C for more than 500 cycles. Even at 1C, the cell loses only 0.06 % per cycle for 1000 cycles with a coulombic efficiency close to 99 %. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The order-to-disorder transition behavior of PS-b-P2VP thin film system

NASA Astrophysics Data System (ADS)

Ahn, Hyungju; Ryu, Du

2013-03-01

We investigated the transition behavior such as the order-to-disorder transition (ODT) for symmetric poly(styrene)-block-poly(2-vinly pridine) (PS-b-P2VP) using SAXS and GISAXS for block copolymer bulks and films. The bulk transition temperature of PS-b-P2VP was significantly influenced by the interfacial interactions in thin films, leading to the different transition temperature. From these results, we will discuss about the interfacial interaction effects on the phase behaviors in bulks and thin films system of PS-b-P2VP.

Direct determination of resonance energy transfer in photolyase: structural alignment for the functional state.

PubMed

Tan, Chuang; Guo, Lijun; Ai, Yuejie; Li, Jiang; Wang, Lijuan; Sancar, Aziz; Luo, Yi; Zhong, Dongping

2014-11-13

Photoantenna is essential to energy transduction in photoinduced biological machinery. A photoenzyme, photolyase, has a light-harvesting pigment of methenyltetrahydrofolate (MTHF) that transfers its excitation energy to the catalytic flavin cofactor FADH¯ to enhance DNA-repair efficiency. Here we report our systematic characterization and direct determination of the ultrafast dynamics of resonance energy transfer from excited MTHF to three flavin redox states in E. coli photolyase by capturing the intermediates formed through the energy transfer and thus excluding the electron-transfer quenching pathway. We observed 170 ps for excitation energy transferring to the fully reduced hydroquinone FADH¯, 20 ps to the fully oxidized FAD, and 18 ps to the neutral semiquinone FADH(•), and the corresponding orientation factors (κ(2)) were determined to be 2.84, 1.53 and 1.26, respectively, perfectly matching with our calculated theoretical values. Thus, under physiological conditions and over the course of evolution, photolyase has adopted the optimized orientation of its photopigment to efficiently convert solar energy for repair of damaged DNA.

Preparation of Mesoporous Ceramics from Polymer Nanotubes

NASA Astrophysics Data System (ADS)

Chen, Dian; Park, Soojin; Chen, Jiun-Tai; Redston, Emily; Russell, Thomas

2009-03-01

Poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) nanotubes were prepared by placing polymer solution into the cylindrical nanopores of an anodic aluminum oxide (AAO) membrane. The PS-b-P4VP nanotubes within the AAO membranes were exposed to tetrahydrofuran vapor to produce uniform spherical micelles along the tube. The tubes were removed from the membranes, then suspended in ethylene glycol, a preferential solvent for P4VP. At 95^ oC, near the glass transition temperature (Tg) of PS, nanotubes with uniform nanopores were obtained by a reconstruction of the nanotubes. As the temperature was increased, mesoporous polymer structures were obtained. Tetraethyl orthosilicate or titanium tetraethoxide, ceramic precursors, were introduced into the 4VP microdomains. After exposure to an oxygen plasma or high temperature, the copolymer was removed and the precursor converted to a mesoporous ceramic. This process offers a simple route for the fabrication of tunable mesoporous ceramic or metallic structures by changing molecular weight of copolymers.

General Syntheses of Nanotubes Induced by Block Copolymer Self-Assembly.

PubMed

Zhao, Jianming; Huang, Wei; Si, Pengchao; Ulstrup, Jens; Diao, Fangyuan; Zhang, Jingdong

2018-06-01

Amphiphilic block copolymer templating strategies are extensively used for syntheses of mesoporous materials. However, monodisperse tubular nanostructures are limited. Here, a general method is developed to synthesize monodisperse nanotubes with narrow diameter distribution induced by self-assembly of block copolymer. 3-Aminophenol (AP) and formaldehyde (F) polymerize and self-assemble with cylindrical PS-b-PEO micelles into worm-like PS-b-PEO@APF composites with uniform diameter (49 ± 3 nm). After template extraction, worm-like APF polymer nanotubes are formed. The structure and morphology of the polymer nanotubes can be tuned by regulating the synthesis conditions. Furthermore, PS-b-PEO@APF composites are uniformly converted to isomorphic carbon nanotubes with large surface area of 662 m 2 g -1 , abundant hierarchical porous frameworks and nitrogen doping. The synthesis can be extended to silica nanotubes. These findings open an avenue to the design of porous materials with controlled structural framework, composition, and properties for a wide range of applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catch and Release of Cytokines Mediated by Tumor Phosphatidylserine Converts Transient Exposure into Long-Lived Inflammation.

PubMed

Oyler-Yaniv, Jennifer; Oyler-Yaniv, Alon; Shakiba, Mojdeh; Min, Nina K; Chen, Ying-Han; Cheng, Sheue-Yann; Krichevsky, Oleg; Altan-Bonnet, Nihal; Altan-Bonnet, Grégoire

2017-06-01

Immune cells constantly survey the host for pathogens or tumors and secrete cytokines to alert surrounding cells of these threats. In vivo, activated immune cells secrete cytokines for several hours, yet an acute immune reaction occurs over days. Given these divergent timescales, we addressed how cytokine-responsive cells translate brief cytokine exposure into phenotypic changes that persist over long timescales. We studied melanoma cell responses to transient exposure to the cytokine interferon γ (IFNγ) by combining a systems-scale analysis of gene expression dynamics with computational modeling and experiments. We discovered that IFNγ is captured by phosphatidylserine (PS) on the surface of viable cells both in vitro and in vivo then slowly released to drive long-term transcription of cytokine-response genes. This mechanism introduces an additional function for PS in dynamically regulating inflammation across diverse cancer and primary cell types and has potential to usher in new immunotherapies targeting PS and inflammatory pathways. Published by Elsevier Inc.

Laser excitation of the n =3 level of positronium for antihydrogen production

NASA Astrophysics Data System (ADS)

Aghion, S.; Amsler, C.; Ariga, A.; Ariga, T.; Bonomi, G.; Bräunig, P.; Bremer, J.; Brusa, R. S.; Cabaret, L.; Caccia, M.; Caravita, R.; Castelli, F.; Cerchiari, G.; Chlouba, K.; Cialdi, S.; Comparat, D.; Consolati, G.; Demetrio, A.; Di Noto, L.; Doser, M.; Dudarev, A.; Ereditato, A.; Evans, C.; Ferragut, R.; Fesel, J.; Fontana, A.; Forslund, O. K.; Gerber, S.; Giammarchi, M.; Gligorova, A.; Gninenko, S.; Guatieri, F.; Haider, S.; Holmestad, H.; Huse, T.; Jernelv, I. L.; Jordan, E.; Kellerbauer, A.; Kimura, M.; Koettig, T.; Krasnicky, D.; Lagomarsino, V.; Lansonneur, P.; Lebrun, P.; Lehner, S.; Liberadzka, J.; Malbrunot, C.; Mariazzi, S.; Marx, L.; Matveev, V.; Mazzotta, Z.; Nebbia, G.; Nedelec, P.; Oberthaler, M.; Pacifico, N.; Pagano, D.; Penasa, L.; Petracek, V.; Pistillo, C.; Prelz, F.; Prevedelli, M.; Ravelli, L.; Resch, L.; Rienäcker, B.; Røhne, O. M.; Rotondi, A.; Sacerdoti, M.; Sandaker, H.; Santoro, R.; Scampoli, P.; Smestad, L.; Sorrentino, F.; Spacek, M.; Storey, J.; Strojek, I. M.; Testera, G.; Tietje, I.; Vamosi, S.; Widmann, E.; Yzombard, P.; Zmeskal, J.; Zurlo, N.; AEgIS Collaboration

2016-07-01

We demonstrate the laser excitation of the n =3 state of positronium (Ps) in vacuum. A combination of a specially designed pulsed slow positron beam and a high-efficiency converter target was used to produce Ps. Its annihilation was recorded by single-shot positronium annihilation lifetime spectroscopy. Pulsed laser excitation of the n =3 level at a wavelength λ ≈205 nm was monitored via Ps photoionization induced by a second intense laser pulse at λ =1064 nm. About 15% of the overall positronium emitted into vacuum was excited to n =3 and photoionized. Saturation of both the n =3 excitation and the following photoionization was observed and explained by a simple rate equation model. The positronium's transverse temperature was extracted by measuring the width of the Doppler-broadened absorption line. Moreover, excitation to Rydberg states n =15 and 16 using n =3 as the intermediate level was observed, giving an independent confirmation of excitation to the 3 3P state.

STIC3 - Silicon Photomultiplier Timing Chip with picosecond resolution

NASA Astrophysics Data System (ADS)

Stankova, Vera; Shen, Wei; Briggl, Konrad; Chen, Huangshan; Fischer, Peter; Gil, Alejandro; Harion, Tobias; Kiworra, Volker; Munwes, Yonathan; Ritzert, Michael; Schultz-Coulon, Hans-Christian

2015-07-01

The diagnostic of pancreas and prostate cancer is a challenging task due to the background noise coming from the closer organs. The EndoToFPET-US project aims to combine the synergy between metabolic and anatomical (ultrasound) image in order to improve the precision in the tumor localization. The goal of the project is to develop a Positron Emission Tomography (PET) system that provides a time-of-flight resolution of 200 ps FWHM for improving the signal to noise ratio and further to improve the medical image quality. In order to achieve this purpose an ASIC has been designed for very high timing resolution in time-of-flight (ToF) applications. In this paper we present the ASIC performance and the first characterization measurements with the 64-channels prototype version (STiC3). Measurements are performed with LYSO scintillator crystal and a Multi Pixel Photon Counter (MPPC). Measurements with the chip show an analog-front-end stage jitter of 35 ps for the first photo-electron equivalent charge and reach 18 ps for the third photo-electron. Coincidence time resolution (CTR) of 240 ps FWHM is measured with 3.1×3.1×15 mm3 LYSO crystal and 50 μm pixel pitch MPPC. Further optimization including the Time-to-Digital Converter (TDC) non-linearity corrections and setup fine tuning are ongoing for achieving the desired CTR of 200 ps FWHM.

Method for observing phase objects without halos and directional shadows

NASA Astrophysics Data System (ADS)

Suzuki, Yoshimasa; Kajitani, Kazuo; Ohde, Hisashi

2015-03-01

A new microscopy method for observing phase objects without halos and directional shadows is proposed. The key optical element is an annular aperture at the front focal plane of a condenser with a larger diameter than those used in standard phase contrast microscopy. The light flux passing through the annular aperture is changed by the specimen's surface profile and then passes through an objective and contributes to image formation. This paper presents essential conditions for realizing the method. In this paper, images of colonies formed by induced pluripotent stem (iPS) cells using this method are compared with the conventional phase contrast method and the bright-field method when the NA of the illumination is small to identify differences among these techniques. The outlines of the iPS cells are clearly visible with this method, whereas they are not clearly visible due to halos when using the phase contrast method or due to weak contrast when using the bright-field method. Other images using this method are also presented to demonstrate a capacity of this method: a mouse ovum and superimposition of several different images of mouse iPS cells.

Interferometric at-wavelength flare characterization of EUV optical systems

DOEpatents

Naulleau, Patrick P.; Goldberg, Kenneth Alan

2001-01-01

The extreme ultraviolet (EUV) phase-shifting point diffraction interferometer (PS/PDI) provides the high-accuracy wavefront characterization critical to the development of EUV lithography systems. Enhancing the implementation of the PS/PDI can significantly extend its spatial-frequency measurement bandwidth. The enhanced PS/PDI is capable of simultaneously characterizing both wavefront and flare. The enhanced technique employs a hybrid spatial/temporal-domain point diffraction interferometer (referred to as the dual-domain PS/PDI) that is capable of suppressing the scattered-reference-light noise that hinders the conventional PS/PDI. Using the dual-domain technique in combination with a flare-measurement-optimized mask and an iterative calculation process for removing flare contribution caused by higher order grating diffraction terms, the enhanced PS/PDI can be used to simultaneously measure both figure and flare in optical systems.

Calcium Phosphate Bioceramics: A Review of Their History, Structure, Properties, Coating Technologies and Biomedical Applications.

PubMed

Eliaz, Noam; Metoki, Noah

2017-03-24

Calcium phosphate (CaP) bioceramics are widely used in the field of bone regeneration, both in orthopedics and in dentistry, due to their good biocompatibility, osseointegration and osteoconduction. The aim of this article is to review the history, structure, properties and clinical applications of these materials, whether they are in the form of bone cements, paste, scaffolds, or coatings. Major analytical techniques for characterization of CaPs, in vitro and in vivo tests, and the requirements of the US Food and Drug Administration (FDA) and international standards from CaP coatings on orthopedic and dental endosseous implants, are also summarized, along with the possible effect of sterilization on these materials. CaP coating technologies are summarized, with a focus on electrochemical processes. Theories on the formation of transient precursor phases in biomineralization, the dissolution and reprecipitation as bone of CaPs are discussed. A wide variety of CaPs are presented, from the individual phases to nano-CaP, biphasic and triphasic CaP formulations, composite CaP coatings and cements, functionally graded materials (FGMs), and antibacterial CaPs. We conclude by foreseeing the future of CaPs.

Calcium Phosphate Bioceramics: A Review of Their History, Structure, Properties, Coating Technologies and Biomedical Applications

PubMed Central

Eliaz, Noam; Metoki, Noah

2017-01-01

Calcium phosphate (CaP) bioceramics are widely used in the field of bone regeneration, both in orthopedics and in dentistry, due to their good biocompatibility, osseointegration and osteoconduction. The aim of this article is to review the history, structure, properties and clinical applications of these materials, whether they are in the form of bone cements, paste, scaffolds, or coatings. Major analytical techniques for characterization of CaPs, in vitro and in vivo tests, and the requirements of the US Food and Drug Administration (FDA) and international standards from CaP coatings on orthopedic and dental endosseous implants, are also summarized, along with the possible effect of sterilization on these materials. CaP coating technologies are summarized, with a focus on electrochemical processes. Theories on the formation of transient precursor phases in biomineralization, the dissolution and reprecipitation as bone of CaPs are discussed. A wide variety of CaPs are presented, from the individual phases to nano-CaP, biphasic and triphasic CaP formulations, composite CaP coatings and cements, functionally graded materials (FGMs), and antibacterial CaPs. We conclude by foreseeing the future of CaPs. PMID:28772697

Upcycling: converting waste plastics into paramagnetic, conducting, solid, pure carbon microspheres.

PubMed

Pol, Vilas Ganpat

2010-06-15

The recent tremendous increase in the volume of waste plastics (WP) will have a harmful environmental impact on the health of living beings. Hundreds of years are required to degrade WP in atmospheric conditions. Hence, in coming years, in addition to traditional recycling services, innovative "upcycling" processes are necessary. This article presents an environmentally benign, solvent-free autogenic process that converts various WP [low density polyethylene (LDPE), high density polyethylene (HDPE), polyethylene terephthalate (PET), polystyrene (PS), or their mixtures] into carbon microspheres (CMSs), an industrially significant, value-added product. The thermal dissociation of these individual or mixed WP in a closed reactor under autogenic pressure ( approximately 1000 psi) produced dry, pure powder of CMSs. In this paper, the optimization of process parameters such as the effect of mixing of WP with other materials, and the role of reaction temperature and time are reported. Employing advanced analytical techniques, the atomic structure, composition, and morphology of as-obtained CMSs were analyzed. The room-temperature paramagnetism in CMSs prepared from waste LDPE, HDPE, and PS was further studied by electron paramagnetic resonance (EPR). The conducting and paramagnetic nature of CMSs holds promise for their potential applications in toners, printers, paints, batteries, lubricants, and tires.

High resolution distributed time-to-digital converter (TDC) in a White Rabbit network

NASA Astrophysics Data System (ADS)

Pan, Weibin; Gong, Guanghua; Du, Qiang; Li, Hongming; Li, Jianmin

2014-02-01

The Large High Altitude Air Shower Observatory (LHAASO) project consists of a complex detector array with over 6000 detector nodes spreading over 1.2 km2 areas. The arrival times of shower particles are captured by time-to-digital converters (TDCs) in the detectors' frontend electronics, the arrival direction of the high energy cosmic ray are then to be reconstructed from the space-time information of all detector nodes. To guarantee the angular resolution of 0.5°, a time synchronization of 500 ps (RMS) accuracy and 100 ps precision must be achieved among all TDC nodes. A technology enhancing Gigabit Ethernet, called the White Rabbit (WR), has shown the capability of delivering sub-nanosecond accuracy and picoseconds precision of synchronization over the standard data packet transfer. In this paper we demonstrate a distributed TDC prototype system combining the FPGA based TDC and the WR technology. With the time synchronization and data transfer services from a compact WR node, separate FPGA-TDC nodes can be combined to provide uniform time measurement information for correlated events. The design detail and test performance will be described in the paper.

Diffusion paths formation for Cu + ions in superionic Cu 6PS 5I single crystals studied in terms of structural phase transition

NASA Astrophysics Data System (ADS)

Gągor, A.; Pietraszko, A.; Kaynts, D.

2005-11-01

In order to understand the structural transformations leading to high ionic conductivity of Cu + ions in Cu 6PS 5I argyrodite compound, the detailed structure analysis based on single-crystal X-ray diffraction has been performed. Below the phase transition at T=(144-169) K Cu 6PS 5I belongs to monoclinic, ferroelastic phase (space group Cc) with ordered copper sublattice. Above Tc delocalization of copper ions begins and crystal changes the symmetry to cubic superstructure with space group F-43 c ( a'=19.528 Å, z=32). Finally, above T1=274 K increasing disordering of the Cu + ions heightens the symmetry to F-43 m ( a=9.794 Å, z=4). In this work, the final structural model of two cubic phases is presented including the detailed temperature evolution of positions and site occupation factors of copper ions ( R1=0.0397 for F-43 c phase, and 0.0245 for F-43 m phase). Possible diffusion paths for the copper ions are represented by means of the atomic displacement factors and split model. The structural results coincide well with the previously reported non-Arrhenius behavior of conductivity and indicate significant change in conduction mechanism.

Dynamic chirp control of all-optical format-converted pulsed data from a multi-wavelength inverse-optical-comb injected semiconductor optical amplifier.

PubMed

Lin, Gong-Ru; Pan, Ci-Ling; Yu, Kun-Chieh

2007-10-01

By spectrally and temporally reshaping the gain-window of a traveling-wave semiconductor optical amplifier (TWSOA) with a backward injected multi- or single-wavelength inverse-optical-comb, we theoretically and experimentally investigate the dynamic frequency chirp of the all-optical 10GBit/s Return-to-Zero (RZ) data-stream format-converted from the TWSOA under strong cross-gain depletion scheme. The multi-wavelength inverse-optical-comb injection effectively depletes the TWSOA gain spectrally and temporally, remaining a narrow gain-window and a reduced spectral linewidth and provide a converted RZ data with a smaller peak-to-peak frequency chirp of 6.7 GHz. Even at high inverse-optical-comb injection power and highly biased current condition for improving the operational bit-rate, the chirp of the multi-wavelength-injection converted RZ pulse is still 2.1-GHz smaller than that obtained by using single-wavelength injection at a cost of slight pulse-width broadening by 1 ps.

Role of Chain Microstructure and Branching on Solution and Thin Film Phase Behavior

DTIC Science & Technology

2015-11-30

0.46:1  PS4  – PI4  60k‐60k   62.9k‐74.8k  1.07  0.457  0.840:1    60k‐120k   62.9k‐116.8k  1.06  0.350  0.54:1    ARO Final Report (PI: M. Kilbey)    5...nominal composition).  PS-PI PS2-PI2 PS4 -PI4 S/I=1 S/I=0.5 ARO Final Report (PI: M. Kilbey)    6    the PS/PVP interface, or possibly bury themselves

Comparison between Phase-Shift Full-Bridge Converters with Noncoupled and Coupled Current-Doubler Rectifier

PubMed Central

Tsai, Cheng-Tao; Tseng, Sheng-Yu

2013-01-01

This paper presents comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier. In high current capability and high step-down voltage conversion, a phase-shift full-bridge converter with a conventional current-doubler rectifier has the common limitations of extremely low duty ratio and high component stresses. To overcome these limitations, a phase-shift full-bridge converter with a noncoupled current-doubler rectifier (NCDR) or a coupled current-doubler rectifier (CCDR) is, respectively, proposed and implemented. In this study, performance analysis and efficiency obtained from a 500 W phase-shift full-bridge converter with two improved current-doubler rectifiers are presented and compared. From their prototypes, experimental results have verified that the phase-shift full-bridge converter with NCDR has optimal duty ratio, lower component stresses, and output current ripple. In component count and efficiency comparison, CCDR has fewer components and higher efficiency at full load condition. For small size and high efficiency requirements, CCDR is relatively suitable for high step-down voltage and high efficiency applications. PMID:24381521

Comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier.

PubMed

Tsai, Cheng-Tao; Su, Jye-Chau; Tseng, Sheng-Yu

2013-01-01

This paper presents comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier. In high current capability and high step-down voltage conversion, a phase-shift full-bridge converter with a conventional current-doubler rectifier has the common limitations of extremely low duty ratio and high component stresses. To overcome these limitations, a phase-shift full-bridge converter with a noncoupled current-doubler rectifier (NCDR) or a coupled current-doubler rectifier (CCDR) is, respectively, proposed and implemented. In this study, performance analysis and efficiency obtained from a 500 W phase-shift full-bridge converter with two improved current-doubler rectifiers are presented and compared. From their prototypes, experimental results have verified that the phase-shift full-bridge converter with NCDR has optimal duty ratio, lower component stresses, and output current ripple. In component count and efficiency comparison, CCDR has fewer components and higher efficiency at full load condition. For small size and high efficiency requirements, CCDR is relatively suitable for high step-down voltage and high efficiency applications.

A hybrid filter to mitigate harmonics caused by nonlinear load and resonance caused by power factor correction capacitor

NASA Astrophysics Data System (ADS)

Adan, N. F.; Soomro, D. M.

2017-01-01

Power factor correction capacitor (PFCC) is commonly installed in industrial applications for power factor correction (PFC). With the expanding use of non-linear equipment such as ASDs, power converters, etc., power factor (PF) improvement has become difficult due to the presence of harmonics. The resulting capacitive impedance of the PFCC may form a resonant circuit with the source inductive reactance at a certain frequency, which is likely to coincide with one of the harmonic frequency of the load. This condition will trigger large oscillatory currents and voltages that may stress the insulation and cause subsequent damage to the PFCC and equipment connected to the power system (PS). Besides, high PF cannot be achieved due to power distortion. This paper presents the design of a three-phase hybrid filter consisting of a single tuned passive filter (STPF) and shunt active power filter (SAPF) to mitigate harmonics and resonance in the PS through simulation using PSCAD/EMTDC software. SAPF was developed using p-q theory. The hybrid filter has resulted in significant improvement on both total harmonic distortion for voltage (THDV) and total demand distortion for current (TDDI) with maximum values of 2.93% and 9.84% respectively which were within the recommended IEEE 519-2014 standard limits. Regarding PF improvement, the combined filters have achieved PF close to desired PF at 0.95 for firing angle, α values up to 40°.

Multicomponent seismic methods for characterizing gas hydrate occurrences and systems in deep-water Gulf of Mexico

USGS Publications Warehouse

Haines, Seth S.; Lee, Myung W.; Collett, Timothy S.; Hardage, Bob A.

2011-01-01

In-situ characterization and quantification of natural gas hydrate occurrences remain critical research directions, whether for energy resource, drilling hazard, or climate-related studies. Marine multicomponent seismic data provide the full seismic wavefield including partial redundancy, and provide a promising set of approaches for gas hydrate characterization. Numerous authors have demonstrated the possibilities of multicomponent data at study sites around the world. We expand on this work by investigating the utility of very densely spaced (10’s of meters) multicomponent receivers (ocean-bottom cables, OBC, or ocean-bottom seismometers, OBS) for gas hydrate studies in the Gulf of Mexico and elsewhere. Advanced processing techniques provide high-resolution compressional-wave (PP) and converted shearwave (PS) reflection images of shallow stratigraphy, as well as P-wave and S-wave velocity estimates at each receiver position. Reflection impedance estimates can help constrain velocity and density, and thus gas hydrate saturation. Further constraint on velocity can be determined through identification of the critical angle and associated phase reversal in both PP and PS wideangle data. We demonstrate these concepts with examples from OBC data from the northeast Green Canyon area and numerically simulated OBS data that are based on properties of known gas hydrate occurrences in the southeast (deeper water) Green Canyon area. These multicomponent data capabilities can provide a wealth of characterization and quantification information that is difficult to obtain with other geophysical methods.

Independence From Parenteral Nutrition and Intravenous Fluid Support During Treatment With Teduglutide Among Patients With Intestinal Failure Associated With Short Bowel Syndrome

PubMed Central

Iyer, Kishore R.; Kunecki, Marek; Boullata, Joseph I.; Fujioka, Ken; Joly, Francisca; Gabe, Simon; Pape, Ulrich-Frank; Schneider, Stéphane M.; Virgili Casas, María Nuria; Ziegler, Thomas R.; Li, Benjamin; Youssef, Nader N.; Jeppesen, Palle B.

2016-01-01

Background: In phase III clinical studies, treatment with teduglutide was associated with clinically meaningful reductions (≥20% from baseline) in parenteral support (PS; parenteral nutrition and/or intravenous fluids) requirements in adult patients with intestinal failure associated with short bowel syndrome (SBS-IF). This analysis reports clinical characteristics of patients who achieved complete independence from PS during teduglutide treatment. Materials and Methods: Post hoc analysis of adult patients who achieved complete PS independence during treatment with teduglutide 0.05 mg/kg/d. Data were pooled from 5 teduglutide clinical trials (2 phase III placebo-controlled trials [NCT00081458 and NCT00798967] and their respective extension studies [NCT00172185, NCT00930644, NCT01560403]). Descriptive statistics were used; no between-group comparisons were performed because of the small sample size and lack of comparator. Results: Of 134 patients, 16 gained oral or enteral autonomy after a median of 5 years of PS dependence and 89 weeks of teduglutide treatment. Demographic and baseline disease characteristics varied among patients (median age, 55 years; 50% men; median baseline PS volume, 5.1 L/wk; median residual small intestine length, 52.5 cm). Most patients who achieved PS independence had colon-in-continuity; however, there was no significant difference in the frequency of PS independence among patients who maintained colon-in-continuity vs those who did not. Conclusion: Findings from this post hoc analysis suggest that oral or enteral autonomy is possible for some patients with SBS-IF who are treated with teduglutide, regardless of baseline characteristics and despite long-term PS dependence. PMID:27875291

Simultaneous chromatic dispersion, polarization-mode-dispersion and OSNR monitoring at 40Gbit/s.

PubMed

Baker-Meflah, Lamia; Thomsen, Benn; Mitchell, John; Bayvel, Polina

2008-09-29

A novel method for independent and simultaneous monitoring of chromatic dispersion (CD), first-order PMD and OSNR in 40Gbit/s systems is proposed and demonstrated. This is performed using in-band tone monitoring of 5GHz, optically down-converted to a low intermediate-frequency (IF) of 10kHz. The measurement provides a large monitoring range with good accuracies for CD (4742+/-100ps/nm), differential group delay (DGD) (200+/-4ps) and OSNR (23+/-1dB), independently of the bit-rate. In addition, the use of electro-absorption modulators (EAM) for the simultaneous down-conversion of all channels and the use of low-speed detectors makes it cost effective for multi-channel operation.

Characterization of nanostructured CuO-porous silicon matrix formed on copper-coated silicon substrate via electrochemical etching

NASA Astrophysics Data System (ADS)

Naddaf, M.; Mrad, O.; Al-zier, A.

2014-06-01

A pulsed anodic etching method has been utilized for nanostructuring of a copper-coated p-type (100) silicon substrate, using HF-based solution as electrolyte. Scanning electron microscopy reveals the formation of a nanostructured matrix that consists of island-like textures with nanosize grains grown onto fiber-like columnar structures separated with etch pits of grooved porous structures. Spatial micro-Raman scattering analysis indicates that the island-like texture is composed of single-phase cupric oxide (CuO) nanocrystals, while the grooved porous structure is barely related to formation of porous silicon (PS). X-ray diffraction shows that both the grown CuO nanostructures and the etched silicon layer have the same preferred (220) orientation. Chemical composition obtained by means of X-ray photoelectron spectroscopic (XPS) analysis confirms the presence of the single-phase CuO on the surface of the patterned CuO-PS matrix. As compared to PS formed on the bare silicon substrate, the room-temperature photoluminescence (PL) from the CuO-PS matrix exhibits an additional weak `blue' PL band as well as a blue shift in the PL band of PS (S-band). This has been revealed from XPS analysis to be associated with the enhancement in the SiO2 content as well as formation of the carbonyl group on the surface in the case of the CuO-PS matrix.

A method to calibrate phase fluctuation in polarization-sensitive swept-source optical coherence tomography

NASA Astrophysics Data System (ADS)

Lu, Zenghai; Kasaragod, Deepa K.; Matcher, Stephen J.

2011-06-01

A phase fluctuation calibration method is presented for polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) using continuous polarization modulation. The method consists of the generation of a continuous triggered tone-burst waveform rather than an asynchronous waveform by use of a function generator and the removal of the global phases of the measured Jones matrices by use of matrix normalization. This could remove the use of auxiliary optical components for the phase fluctuation compensation in the system, which reduces the system complexity. Phase fluctuation calibration is necessary to obtain the reference Jones matrix by averaging the measured Jones matrices at sample surfaces. Measurements on an equine tendon sample were made by the PS-SS-OCT system to validate the proposed method.

Spontaneous Evolution of Nanostructure in Composite Films Consisting of Mixtures of Two Different Block Copolymer Micelles

NASA Astrophysics Data System (ADS)

Kim, Sehee; Char, Kookheon; Sohn, Byeong-Hyeok

2010-03-01

Diblock copolymers consisting of two immiscible polymer blocks covalently bonded together form various self-assembled nanostructures such as spheres, cylinders, and lamellae in bulk phase. In a selective solvent, however, they assemble into micelles with soluble corona brushes and immiscible cores. Both polystyrene-poly(4-vinylpyridine) (PS-b-P4VP) and polystyrene-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymers form micelles with PS coronas and P4VP or P2VP cores in a PS selective solvent (toluene). By varying the mixture ratio between PS-b-P4VP and PS-b-P2VP, composite films based on the micellar mixtures of PS-b-P4VP and PS-b-P2VP were obtained by spin-coating, followed by the solvent annealing with tetrahydrofuran (THF) vapor. Since THF is a solvent for both PS and P2VP blocks and, at the same time, a non-solvent for the P4VP block, PS-P2VP micelles transformed to lamellar multilayers while PS-P4VP micelles remained intact during the THF annealing. The spontaneous evolution of nanostructure in composite films consisting of lamellae layers with BCP micelles were investigated in detail by cross-sectional TEM and AFM.

30W, 10μJ, 10-ps SPM-induced spectrally compressed pulse generation in a low non-linearity ytterbium-doped rod-type fibre amplifier

NASA Astrophysics Data System (ADS)

Zaouter, Y.; Cormier, E.; Rigail, P.; Hönninger, C.; Mottay, E.

2007-02-01

The concept of spectral compression induced by self phase modulation is used to generate transform-limited 10ps pulses in a rare-earth-doped low nonlinearity fibre amplifier. The seed source of the amplifier stage is a high power, Yb 3+:KGW bulk oscillator which delivers 500 fs transform-limited pulses at 10MHz repetition rate. After a reduction of the repetition rate down to 3MHz, the femtosecond pulses are negatively chirped by transmission gratings in a compressor arrangement. The resulting 10ps pulses are further seeded into the power amplifier and up to 32W output power is obtained while the spectral bandwidth is reduced to less than 0.5 nm by means of self phase modulation.

Atomistic insights into the nanosecond long amorphization and crystallization cycle of nanoscale G e2S b2T e5 : An ab initio molecular dynamics study

NASA Astrophysics Data System (ADS)

Branicio, Paulo S.; Bai, Kewu; Ramanarayan, H.; Wu, David T.; Sullivan, Michael B.; Srolovitz, David J.

2018-04-01

The complete process of amorphization and crystallization of the phase-change material G e2S b2T e5 is investigated using nanosecond ab initio molecular dynamics simulations. Varying the quench rate during the amorphization phase of the cycle results in the generation of a variety of structures from entirely crystallized (-0.45 K/ps) to entirely amorphized (-16 K/ps). The 1.5-ns annealing simulations indicate that the crystallization process depends strongly on both the annealing temperature and the initial amorphous structure. The presence of crystal precursors (square rings) in the amorphous matrix enhances nucleation/crystallization kinetics. The simulation data are used to construct a combined continuous-cooling-transformation (CCT) and temperature-time-transformation (TTT) diagram. The nose of the CCT-TTT diagram corresponds to the minimum time for the onset of homogenous crystallization and is located at 600 K and 70 ps. That corresponds to a critical cooling rate for amorphization of -4.5 K/ps. The results, in excellent agreement with experimental observations, suggest that a strategy that utilizes multiple quench rates and annealing temperatures may be used to effectively optimize the reversible switching speed and enable fast and energy-efficient phase-change memories.

Purely wavelength- and amplitude-modulated quartz-enhanced photoacoustic spectroscopy.

PubMed

Patimisco, Pietro; Sampaolo, Angelo; Bidaux, Yves; Bismuto, Alfredo; Scott, Marshall; Jiang, James; Muller, Antoine; Faist, Jerome; Tittel, Frank K; Spagnolo, Vincenzo

2016-11-14

We report here on a quartz-enhanced photoacoustic (QEPAS) sensor employing a quantum cascade laser (QCL) structure capable of operating in a pure amplitude or wavelength modulation configuration. The QCL structure is composed of three electrically independent sections: Gain, Phase (PS) and Master Oscillator (MO). Selective current pumping of these three sections allows obtaining laser wavelength tuning without changes in the optical power, and power modulation without emission wavelength shifts. A pure QEPAS amplitude modulation condition is obtained by modulating the PS current, while pure wavelength modulation is achieved by modulating simultaneously the MO and PS QCL sections and slowly scanning the DC current level injected in the PS section.

Influence of the external DEM on PS-InSAR processing and results on Northern Appennine slopes

NASA Astrophysics Data System (ADS)

Bayer, B.; Schmidt, D. A.; Simoni, A.

2014-12-01

We present an InSAR analysis of slow moving landslide in the Northern Appennines, Italy, and assess the dependencies on the choice of DEM. In recent years, advanced processing techniques for synthetic aperture radar interferometry (InSAR) have been applied to measure slope movements. The persistent scatterers (PS-InSAR) approach is probably the most widely used and some codes are now available in the public domain. The Stanford method of Persistent Scatterers (StamPS) has been successfully used to analyze landslide areas. One problematic step in the processing chain is the choice of an external DEM that is used to model and remove the topographic phase in a series of interferograms in order to obtain the phase contribution caused by surface deformation. The choice is not trivial, because the PS InSAR results differ significantly in terms of PS identification, positioning, and the resulting deformation signal. We use four different DEMs to process a set of 18 ASAR (Envisat) scenes over a mountain area (~350 km2) of the Northern Appennines of Italy, using StamPS. Slow-moving landslides control the evolution of the landscape and cover approximately 30% of the territory. Our focus in this presentation is to evaluate the influence of DEM resolution and accuracy by comparing PS-InSAR results. On an areal basis, we perform a statistical analysis of displacement time-series to make the comparison. We also consider two case studies to illustrate the differences in terms of PS identification, number and estimated displacements. It is clearly shown that DEM accuracy positively influences the number of PS, while line-of-sight rates differ from case to case and can result in deformation signals that are difficult to interpret. We also take advantage of statistical tools to analyze the obtained time-series datasets for the whole study area. Results indicate differences in the style and amount of displacement that can be related to the accuracy of the employed DEM.

Anticipatory phase correction in sensorimotor synchronization.

PubMed

Repp, Bruno H; Moseley, Gordon P

2012-10-01

Studies of phase correction in sensorimotor synchronization often introduce timing perturbations that are unpredictable with regard to direction, magnitude, and position in the stimulus sequence. If participants knew any or all of these parameters in advance, would they be able to anticipate perturbations and thus regain synchrony more quickly? In Experiment 1, we asked musically trained participants to tap in synchrony with short isochronous tone sequences containing a phase shift (PS) of -100, -40, 40, or 100 ms and provided advance information about its direction, position, or both (but not about its magnitude). The first two conditions had little effect, but in the third condition participants shifted their tap in anticipation of the PS, though only by about ±40 ms on average. The phase correction response to the residual PS was also enhanced. In Experiment 2, we provided complete advance information about PSs of various magnitudes either at the time of the immediately preceding tone ("late") or at the time of the tone one position back ("early") while also varying sequence tempo. Anticipatory phase correction was generally conservative and was impeded by fast tempo in the "late" condition. At fast tempi in both conditions, advancing a tap was more difficult than delaying a tap. The results indicate that temporal constraints on anticipatory phase correction resemble those on reactive phase correction. While the latter is usually automatic, this study shows that phase correction can also be controlled consciously for anticipatory purposes. Copyright © 2011 Elsevier B.V. All rights reserved.

Simultaneous DC and three phase output using hybrid converter

NASA Astrophysics Data System (ADS)

Surenderanath, S.; Rathnavel, P.; Prakash, G.; Rayavel, P.

2018-04-01

This Paper introduces new hybrid converter topologies which can supply simultaneously three phase AC as well as DC from a single DC source. The new Hybrid Converter is derived from the single switch controlled Boost converter by replacing the controlled switch with voltage source inverter (VSI). This new hybrid converter has the advantages like reduced number of switches as compared with conventional design having separate converter for supplying three phase AC and DC loads, provide DC and three AC outputs with an increased reliability, resulting from the inherent shoot through protection in the inverter stage. The proposed converter, studied in this paper, is called Boost-Derived Hybrid Converter (BDHC) as it is obtained from the conventional boost topology. A DSPIC based feedback controller is designed to regulate the DC as well as AC outputs. The proposed Converter can supply DC and AC loads at 95 V and 35 V (line to ground) respectively from a 48 V DC source.

Plasma Spray-PVD: A New Thermal Spray Process to Deposit Out of the Vapor Phase

NASA Astrophysics Data System (ADS)

von Niessen, Konstantin; Gindrat, Malko

2011-06-01

Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco AG (Switzerland). Even though it is a thermal spray process, it can deposit coatings out of the vapor phase. The basis of PS-PVD is the low pressure plasma spraying (LPPS) technology that has been well established in industry for several years. In comparison to conventional vacuum plasma spraying (VPS) or low pressure plasma spraying (LPPS), the new proposed process uses a high energy plasma gun operated at a reduced work pressure of 0.1 kPa (1 mbar). Owing to the high energy plasma and further reduced work pressure, PS-PVD is able to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional physical vapor deposition (PVD) technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and electron beam-physical vapor deposition (EB-PVD) coatings. In contrast to EB-PVD, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume. Owing to the forced gas stream of the plasma jet, complex shaped parts such as multi-airfoil turbine vanes can be coated with columnar thermal barrier coatings using PS-PVD. Even shadowed areas and areas which are not in the line of sight of the coating source can be coated homogeneously. This article reports on the progress made by Sulzer Metco in developing a thermal spray process to produce coatings out of the vapor phase. Columnar thermal barrier coatings made of Yttria-stabilized Zircona (YSZ) are optimized to serve in a turbine engine. This process includes not only preferable coating properties such as strain tolerance and erosion resistance but also the simultaneous coverage of multiple air foils.

Receiver function analysis applied to refraction survey data

NASA Astrophysics Data System (ADS)

Subaru, T.; Kyosuke, O.; Hitoshi, M.

2008-12-01

For the estimation of the thickness of oceanic crust or petrophysical investigation of subsurface material, refraction or reflection seismic exploration is one of the methods frequently practiced. These explorations use four-component (x,y,z component of acceleration and pressure) seismometer, but only compressional wave or vertical component of seismometers tends to be used in the analyses. Hence, it is needed to use shear wave or lateral component of seismograms for more precise investigation to estimate the thickness of oceanic crust. Receiver function is a function at a place that can be used to estimate the depth of velocity interfaces by receiving waves from teleseismic signal including shear wave. Receiver function analysis uses both vertical and horizontal components of seismograms and deconvolves the horizontal with the vertical to estimate the spectral difference of P-S converted waves arriving after the direct P wave. Once the phase information of the receiver function is obtained, then one can estimate the depth of the velocity interface. This analysis has advantage in the estimation of the depth of velocity interface including Mohorovicic discontinuity using two components of seismograms when P-to-S converted waves are generated at the interface. Our study presents results of the preliminary study using synthetic seismograms. First, we use three types of geological models that are composed of a single sediment layer, a crust layer, and a sloped Moho, respectively, for underground sources. The receiver function can estimate the depth and shape of Moho interface precisely for the three models. Second, We applied this method to synthetic refraction survey data generated not by earthquakes but by artificial sources on the ground or sea surface. Compressional seismic waves propagate under the velocity interface and radiate converted shear waves as well as at the other deep underground layer interfaces. However, the receiver function analysis applied to the second model cannot clearly estimate the velocity interface behind S-P converted wave or multi-reflected waves in a sediment layer. One of the causes is that the incidence angles of upcoming waves are too large compared to the underground source model due to the slanted interface. As a result, incident converted shear waves have non-negligible energy contaminating the vertical component of seismometers. Therefore, recorded refraction waves need to be transformed from depth-lateral coordinate into radial-tangential coordinate, and then Ps converted waves can be observed clearly. Finally, we applied the receiver function analysis to a more realistic model. This model has not only similar sloping Mohorovicic discontinuity and surface source locations as second model but the surface water layer. Receivers are aligned on the sea bottom (OBS; Ocean Bottom Seismometer survey case) Due to intricately bounced reflections, simulated seismic section becomes more complex than the other previously-mentioned models. In spite of the complexity in the seismic records, we could pick up the refraction waves from Moho interface, after stacking more than 20 receiver functions independently produced from each shot gather. After these processing, the receiver function analysis is justified as a method to estimate the depths of velocity interfaces and would be the applicable method for refraction wave analysis. The further study will be conducted for more realistic model that contain inhomogeneous sediment model, for example, and finally used in the inversion of the depth of velocity interfaces like Moho.

Chirp and error rate analyses of an optical-injection gain-switching VCSEL based all-optical NRZ-to-PRZ converter.

PubMed

Lin, Chia-Chi; Kuo, Hao-Chung; Peng, Peng-Chun; Lin, Gong-Ru

2008-03-31

Optically injection-locked single-wavelength gain-switching VCSEL based all-optical converter is demonstrated to generate RZ data at 2.5 Gbit/s with bit-error-rate of 10(-9) under receiving power of -29.3 dBm. A modified rate equation model is established to elucidate the optical injection induced gain-switching and NRZ-to-RZ data conversion in the VCSEL. The peak-to-peak frequency chirp of the VCSEL based NRZ-to-RZ is 4.5 GHz associated with a reduced frequency chirp rate of 178 MHz/ps at input optical NRZ power of -21 dBm, which is almost decreasing by a factor of 1/3 comparing with chirp on the SOA based NRZ-to-RZ converter reported previously. The power penalty of the BER measured back-to-back is about 2 dB from 1 Gbit/s to 2.5 Gbit/s.

Controlled longitudinal emittance blow-up using band-limited phase noise in CERN PSB

NASA Astrophysics Data System (ADS)

Quartullo, D.; Shaposhnikova, E.; Timko, H.

2017-07-01

Controlled longitudinal emittance blow-up (from 1 eVs to 1.4 eVs) for LHC beams in the CERN PS Booster is currently achievied using sinusoidal phase modulation of a dedicated high-harmonic RF system. In 2021, after the LHC injectors upgrade, 3 eVs should be extracted to the PS. Even if the current method may satisfy the new requirements, it relies on low-power level RF improvements. In this paper another method of blow-up was considered, that is the injection of band-limited phase noise in the main RF system (h=1), never tried in PSB but already used in CERN SPS and LHC, under different conditions (longer cycles). This technique, which lowers the peak line density and therefore the impact of intensity effects in the PSB and the PS, can also be complementary to the present method. The longitudinal space charge, dominant in the PSB, causes significant synchrotron frequency shifts with intensity, and its effect should be taken into account. Another complication arises from the interaction of the phase loop with the injected noise, since both act on the RF phase. All these elements were studied in simulations of the PSB cycle with the BLonD code, and the required blow-up was achieved.

TH-CD-201-09: High Spatial Resolution Absorbed Dose to Water Measurements Using Optical Calorimetry in Megavoltage External Beam Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flores-Martinez, E; DeWerd, L; Radtke, J

2016-06-15

Purpose: To develop and implement a high spatial resolution calorimeter methodology to measure absorbed dose to water (ADW) using phase shifts (PSs) of light passing through a water phantom and to compare measurements with theoretical calculations. Methods: Radiation-induced temperature changes were measured using the PSs of a He-Ne laser beam passing through a (10×10×10) cm{sup 3} water phantom. PSs were measured using a Michelson interferometer and recording the time-dependent fringe patterns on a CCD camera. The phantom was positioned at the center of the radiation field. A Varian 21EX was used to deliver 500 MU from a 9 MeV beammore » using a (6×6) cm{sup 2} cone. A 127cm SSD was used and the PSs were measured at depths ranging from of 1.90cm to 2.10cm in steps of 0.05cm by taking profiles at the corresponding rows across the image. PSs were computed by taking the difference between pre- and post-irradiation image frames and then measuring the amplitude of the resulting image profiles. An amplitude-to-PS calibration curve was generated using a piezoelectric transducer to mechanically induce PSs between 0.05 and 1.50 radians in steps of 0.05 radians. The temperature dependence of the refractive index of water at 632.8nm was used to convert PSs to ADW. Measured results were compared with ADW values calculated using the linac output calibration and commissioning data. Results: Milli-radian resolution in PS measurement was achieved using the described methodology. Measured radiation-induced PSs ranged from 0.10 ± 0.01 to 0.12 ± 0.01 radians at the investigated depths. After converting PSs to ADW, measured and calculated ADW values agreed within the measurement uncertainty. Conclusion: This work shows that interferometer-based calorimetry measurements are capable of achieving sub-millimeter resolution measuring 2D temperature/dose distributions, which are particularly useful for characterizing beams from modalities such as SRS, proton therapy, or microbeams.« less

Experimental progress in positronium laser physics

NASA Astrophysics Data System (ADS)

Cassidy, David B.

2018-03-01

The field of experimental positronium physics has advanced significantly in the last few decades, with new areas of research driven by the development of techniques for trapping and manipulating positrons using Surko-type buffer gas traps. Large numbers of positrons (typically ≥106) accumulated in such a device may be ejected all at once, so as to generate an intense pulse. Standard bunching techniques can produce pulses with ns (mm) temporal (spatial) beam profiles. These pulses can be converted into a dilute Ps gas in vacuum with densities on the order of 107 cm-3 which can be probed by standard ns pulsed laser systems. This allows for the efficient production of excited Ps states, including long-lived Rydberg states, which in turn facilitates numerous experimental programs, such as precision optical and microwave spectroscopy of Ps, the application of Stark deceleration methods to guide, decelerate and focus Rydberg Ps beams, and studies of the interactions of such beams with other atomic and molecular species. These methods are also applicable to antihydrogen production and spectroscopic studies of energy levels and resonances in positronium ions and molecules. A summary of recent progress in this area will be given, with the objective of providing an overview of the field as it currently exists, and a brief discussion of some future directions.

A statistical model of false negative and false positive detection of phase singularities.

PubMed

Jacquemet, Vincent

2017-10-01

The complexity of cardiac fibrillation dynamics can be assessed by analyzing the distribution of phase singularities (PSs) observed using mapping systems. Interelectrode distance, however, limits the accuracy of PS detection. To investigate in a theoretical framework the PS false negative and false positive rates in relation to the characteristics of the mapping system and fibrillation dynamics, we propose a statistical model of phase maps with controllable number and locations of PSs. In this model, phase maps are generated from randomly distributed PSs with physiologically-plausible directions of rotation. Noise and distortion of the phase are added. PSs are detected using topological charge contour integrals on regular grids of varying resolutions. Over 100 × 10 6 realizations of the random field process are used to estimate average false negative and false positive rates using a Monte-Carlo approach. The false detection rates are shown to depend on the average distance between neighboring PSs expressed in units of interelectrode distance, following approximately a power law with exponents in the range of 1.14 to 2 for false negatives and around 2.8 for false positives. In the presence of noise or distortion of phase, false detection rates at high resolution tend to a non-zero noise-dependent lower bound. This model provides an easy-to-implement tool for benchmarking PS detection algorithms over a broad range of configurations with multiple PSs.

Diffusion paths formation for Cu{sup +} ions in superionic Cu{sub 6}PS{sub 5}I single crystals studied in terms of structural phase transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gagor, A.; Pietraszko, A.; Kaynts, D.

2005-11-15

In order to understand the structural transformations leading to high ionic conductivity of Cu{sup +} ions in Cu{sub 6}PS{sub 5}I argyrodite compound, the detailed structure analysis based on single-crystal X-ray diffraction has been performed. Below the phase transition at T{sub c}=(144-169)K Cu{sub 6}PS{sub 5}I belongs to monoclinic, ferroelastic phase (space group Cc) with ordered copper sublattice. Above T{sub c} delocalization of copper ions begins and crystal changes the symmetry to cubic superstructure with space group F-43c (a{sup '}=19.528A, z=32). Finally, above T{sub 1}=274K increasing disordering of the Cu{sup +} ions heightens the symmetry to F-43m (a=9.794A, z=4). In this work,more » the final structural model of two cubic phases is presented including the detailed temperature evolution of positions and site occupation factors of copper ions (R{sub 1}=0.0397 for F-43c phase, and 0.0245 for F-43m phase). Possible diffusion paths for the copper ions are represented by means of the atomic displacement factors and split model. The structural results coincide well with the previously reported non-Arrhenius behavior of conductivity and indicate significant change in conduction mechanism.« less

Sequential steps of macroautophagy and chaperone-mediated autophagy are involved in the irreversible process of posterior silk gland histolysis during metamorphosis of Bombyx mori.

PubMed

Shiba, Hajime; Yabu, Takeshi; Sudayama, Makoto; Mano, Nobuhiro; Arai, Naoto; Nakanishi, Teruyuki; Hosono, Kuniaki

2016-04-15

To elucidate the degradation process of the posterior silk gland during metamorphosis of the silkworm ITALIC! Bombyx mori, tissues collected on the 6th day after entering the 5th instar (V6), prior to spinning (PS), during spinning (SP) and after cocoon formation (CO) were used to analyze macroautophagy, chaperone-mediated autophagy (CMA) and the adenosine triphosphate (ATP)-dependent ubiquitin proteasome. Immediately after entering metamorphosis stage PS, the levels of ATP and phosphorylated p70S6 kinase protein decreased spontaneously and continued to decline at SP, followed by a notable restoration at CO. In contrast, phosphorylated AMP-activated protein kinase α (AMPKα) showed increases at SP and CO. Most of the Atg8 protein was converted to form II at all stages. The levels of ubiquitinated proteins were high at SP and CO, and low at PS. The proteasome activity was high at V6 and PS but low at SP and CO. In the isolated lysosome fractions, levels of Hsc70/Hsp70 protein began to increase at PS and continued to rise at SP and CO. The lysosomal cathepsin B/L activity showed a dramatic increase at CO. Our results clearly demonstrate that macroautophagy occurs before entering the metamorphosis stage and strongly suggest that the CMA pathway may play an important role in the histolysis of the posterior silk gland during metamorphosis. © 2016. Published by The Company of Biologists Ltd.

Sub-nanosecond clock synchronization and trigger management in the nuclear physics experiment AGATA

NASA Astrophysics Data System (ADS)

Bellato, M.; Bortolato, D.; Chavas, J.; Isocrate, R.; Rampazzo, G.; Triossi, A.; Bazzacco, D.; Mengoni, D.; Recchia, F.

2013-07-01

The new-generation spectrometer AGATA, the Advanced GAmma Tracking Array, requires sub-nanosecond clock synchronization among readout and front-end electronics modules that may lie hundred meters apart. We call GTS (Global Trigger and Synchronization System) the infrastructure responsible for precise clock synchronization and for the trigger management of AGATA. It is made of a central trigger processor and nodes, connected in a tree structure by means of optical fibers operated at 2Gb/s. The GTS tree handles the synchronization and the trigger data flow, whereas the trigger processor analyses and eventually validates the trigger primitives centrally. Sub-nanosecond synchronization is achieved by measuring two different types of round-trip times and by automatically correcting for phase-shift differences. For a tree of depth two, the peak-to-peak clock jitter at each leaf is 70 ps; the mean phase difference is 180 ps, while the standard deviation over such phase difference, namely the phase equalization repeatability, is 20 ps. The GTS system has run flawlessly for the two-year long AGATA campaign, held at the INFN Legnaro National Laboratories, Italy, where five triple clusters of the AGATA sub-array were coupled with a variety of ancillary detectors.

High speed and high resolution interrogation of a fiber Bragg grating sensor based on microwave photonic filtering and chirped microwave pulse compression.

PubMed

Xu, Ou; Zhang, Jiejun; Yao, Jianping

2016-11-01

High speed and high resolution interrogation of a fiber Bragg grating (FBG) sensor based on microwave photonic filtering and chirped microwave pulse compression is proposed and experimentally demonstrated. In the proposed sensor, a broadband linearly chirped microwave waveform (LCMW) is applied to a single-passband microwave photonic filter (MPF) which is implemented based on phase modulation and phase modulation to intensity modulation conversion using a phase modulator (PM) and a phase-shifted FBG (PS-FBG). Since the center frequency of the MPF is a function of the central wavelength of the PS-FBG, when the PS-FBG experiences a strain or temperature change, the wavelength is shifted, which leads to the change in the center frequency of the MPF. At the output of the MPF, a filtered chirped waveform with the center frequency corresponding to the applied strain or temperature is obtained. By compressing the filtered LCMW in a digital signal processor, the resolution is improved. The proposed interrogation technique is experimentally demonstrated. The experimental results show that interrogation sensitivity and resolution as high as 1.25 ns/με and 0.8 με are achieved.

Origin of high piezoelectric activity in ferroelectric (K0.44Na0.52Li0.04)-(Nb0.84Ta0.1Sb0.06)O3 ceramics

NASA Astrophysics Data System (ADS)

Akdoǧan, E. K.; Kerman, K.; Abazari, M.; Safari, A.

2008-03-01

We study the temperature dependence of dielectric constant (K) and spontaneous polarization (Ps) in the range of -95-200°C. Cubic (C)-tetragonal (T) and T-orthorhombic (O) transitions are observed at 264 and 25°C, respectively. The Curie-Weiss temperature of C-T transition is 249°C, indicating it is first order. X-ray data indicate T-O phase coexistence at 25°C. A singularity in Ps at 25°C and a T-O phase coexistence spanning 25-31°C was observed, wherein Ps increases from 17×10-2C /m2 at 31°Cto23×10-2C/m2 25°C. The transition at 25°C appears diffusionless and polymorphic with martensite start and finish temperatures of 31 and 25°C, respectively. The maximum in d33 is 345pC/N and is attributed to the instability at 25°C, where Ps and K show singularity.

3D Architecture and evolution of the Po Plain-Northern Adriatic Foreland basin during Plio-Pleistocene time

NASA Astrophysics Data System (ADS)

Amadori, Chiara; Toscani, Giovanni; Ghielmi, Manlio; Maesano, Francesco Emanuele; D'Ambrogi, Chiara; Lombardi, Stefano; Milanesi, Riccardo; Panara, Yuri; Di Giulio, Andrea

2017-04-01

The Pliocene-Pleistocene tectonic and sedimentary evolution of the eastern Po Plain and northern Adriatic Foreland Basin (PPAF) (extended ca. 35,000 km2) was the consequence of severe Northern Apennine compressional activity and climate-driven eustatic changes. According with the 2D seismic interpretation, facies analysis and sequence stratigraphy approach by Ghielmi et al. (2013 and references therein), these tectono-eustatic phases generated six basin-scale unconformities referred as Base Pliocene (PL1), Intra-Zanclean (PL2), Intra-Piacenzian (PL3), Gelasian (PL4), Base Calabrian (PS1) and Late Calabrian (PS2). We present a basin-wide detailed 3D model of the PPAF region, derived from the interpretation of these unconformities in a dense network of seismic lines (ca. 6,000 km) correlated with more than 200 well stratigraphies (courtesy of ENI E&P). The initial 3D time-model has been time-to-depth converted using the 3D velocity model created with Vel-IO 3D, a tool for 3D depth conversions and then validated and integrated with depth domain dataset from bibliography and well log. Resultant isobath and isopach maps are produced to inspect step-by-step the basin paleogeographic evolution; it occurred through alternating stages of simple and fragmented foredeeps. Changes in the basin geometry through time, from the inner sector located in the Emilia-Romagna Apennines to the outermost region (Veneto and northern Adriatic Sea), were marked by repeated phases of outward migration of two large deep depocenters located in front of Emilia arcs on the west, and in front of Ferrara-Romagna thrusts on the east. During late Pliocene-early Pleistocene, the inner side of the Emilia-Romagna arcs evolved into an elongated deep thrust-top basin due to a strong foredeep fragmentation then, an overall tectono-stratigraphic analysis shows also a decreasing trend of tectonic intensity of the Northern Apennine since Pleistocene until present.

High-performance electronics for time-of-flight PET systems

NASA Astrophysics Data System (ADS)

Choong, W.-S.; Peng, Q.; Vu, C. Q.; Turko, B. T.; Moses, W. W.

2013-01-01

We have designed and built a high-performance readout electronics system for time-of-flight positron emission tomography (TOF PET) cameras. The electronics architecture is based on the electronics for a commercial whole-body PET camera (Siemens/CPS Cardinal electronics), modified to improve the timing performance. The fundamental contributions in the electronics that can limit the timing resolution include the constant fraction discriminator (CFD), which converts the analog electrical signal from the photo-detector to a digital signal whose leading edge is time-correlated with the input signal, and the time-to-digital converter (TDC), which provides a time stamp for the CFD output. Coincident events are identified by digitally comparing the values of the time stamps. In the Cardinal electronics, the front-end processing electronics are performed by an Analog subsection board, which has two application-specific integrated circuits (ASICs), each servicing a PET block detector module. The ASIC has a built-in CFD and TDC. We found that a significant degradation in the timing resolution comes from the ASIC's CFD and TDC. Therefore, we have designed and built an improved Analog subsection board that replaces the ASIC's CFD and TDC with a high-performance CFD (made with discrete components) and TDC (using the CERN high-performance TDC ASIC). The improved Analog subsection board is used in a custom single-ring LSO-based TOF PET camera. The electronics system achieves a timing resolution of 60 ps FWHM. Prototype TOF detector modules are read out with the electronics system and give coincidence timing resolutions of 259 ps FWHM and 156 ps FWHM for detector modules coupled to LSO and LaBr3 crystals respectively.

High-performance electronics for time-of-flight PET systems.

PubMed

Choong, W-S; Peng, Q; Vu, C Q; Turko, B T; Moses, W W

2013-01-01

We have designed and built a high-performance readout electronics system for time-of-flight positron emission tomography (TOF PET) cameras. The electronics architecture is based on the electronics for a commercial whole-body PET camera (Siemens/CPS Cardinal electronics), modified to improve the timing performance. The fundamental contributions in the electronics that can limit the timing resolution include the constant fraction discriminator (CFD), which converts the analog electrical signal from the photo-detector to a digital signal whose leading edge is time-correlated with the input signal, and the time-to-digital converter (TDC), which provides a time stamp for the CFD output. Coincident events are identified by digitally comparing the values of the time stamps. In the Cardinal electronics, the front-end processing electronics are performed by an Analog subsection board, which has two application-specific integrated circuits (ASICs), each servicing a PET block detector module. The ASIC has a built-in CFD and TDC. We found that a significant degradation in the timing resolution comes from the ASIC's CFD and TDC. Therefore, we have designed and built an improved Analog subsection board that replaces the ASIC's CFD and TDC with a high-performance CFD (made with discrete components) and TDC (using the CERN high-performance TDC ASIC). The improved Analog subsection board is used in a custom single-ring LSO-based TOF PET camera. The electronics system achieves a timing resolution of 60 ps FWHM. Prototype TOF detector modules are read out with the electronics system and give coincidence timing resolutions of 259 ps FWHM and 156 ps FWHM for detector modules coupled to LSO and LaBr 3 crystals respectively.

Method to calibrate phase fluctuation in polarization-sensitive swept-source optical coherence tomography

NASA Astrophysics Data System (ADS)

Lu, Zenghai; Kasaragod, Deepa K.; Matcher, Stephen J.

2011-07-01

We present a phase fluctuation calibration method for polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) using continuous polarization modulation. The method uses a low-voltage broadband polarization modulator driven by a synchronized sinusoidal burst waveform rather than an asynchronous waveform, together with the removal of the global phases of the measured Jones matrices by the use of matrix normalization. This makes it possible to average the measured Jones matrices to remove the artifact due to the speckle noise of the signal in the sample without introducing auxiliary optical components into the sample arm. This method was validated on measurements of an equine tendon sample by the PS-SS-OCT system.

Nonideal mixing of phosphatidylserine and phosphatidylcholine in the fluid lamellar phase.

PubMed Central

Huang, J; Swanson, J E; Dibble, A R; Hinderliter, A K; Feigenson, G W

1993-01-01

The mixing of phosphatidylserine (PS) and phosphatidylcholine (PC) in fluid bilayer model membranes was studied by measuring binding of aqueous Ca2+ ions. The measured [Ca2+]aq was used to derive the activity coefficient for PS, gamma PS, in the lipid mixture. For (16:0, 18:1) PS in binary mixtures with either (16:0, 18:1)PC, (14:1, 14:1)PC, or (18:1, 18:1)PC, gamma PS > 1; i.e., mixing is nonideal, with PS and PC clustered rather than randomly distributed, despite the electrostatic repulsion between PS headgroups. To understand better this mixing behavior, Monte Carlo simulations of the PS/PC distributions were performed, using Kawasaki relaxation. The excess energy was divided into an electrostatic term Uel and one adjustable term including all other nonideal energy contributions, delta Em. Uel was calculated using a discrete charge theory. Kirkwood's coupling parameter method was used to calculate the excess free energy of mixing, delta GEmix, hence In gamma PS,calc. The values of In gamma PS,calc were equalized by adjusting delta Em in order to find the simulated PS/PC distribution that corresponded to the experimental results. We were thus able to compare the smeared charge calculation of [Ca2+]surf with a calculation ("masked evaluation method") that recognized clustering of the negatively charged PS: clustering was found to have a modest effect on [Ca2+]surf, relative to the smeared charge model. Even though both PS and PC tend to cluster, the long-range nature of the electrostatic repulsion reduces the extent of PS clustering at low PS mole fraction compared to PC clustering at an equivalent low PC mole fraction. PMID:8457667

Nonideal mixing of phosphatidylserine and phosphatidylcholine in the fluid lamellar phase.

PubMed

Huang, J; Swanson, J E; Dibble, A R; Hinderliter, A K; Feigenson, G W

1993-02-01

The mixing of phosphatidylserine (PS) and phosphatidylcholine (PC) in fluid bilayer model membranes was studied by measuring binding of aqueous Ca2+ ions. The measured [Ca2+]aq was used to derive the activity coefficient for PS, gamma PS, in the lipid mixture. For (16:0, 18:1) PS in binary mixtures with either (16:0, 18:1)PC, (14:1, 14:1)PC, or (18:1, 18:1)PC, gamma PS > 1; i.e., mixing is nonideal, with PS and PC clustered rather than randomly distributed, despite the electrostatic repulsion between PS headgroups. To understand better this mixing behavior, Monte Carlo simulations of the PS/PC distributions were performed, using Kawasaki relaxation. The excess energy was divided into an electrostatic term Uel and one adjustable term including all other nonideal energy contributions, delta Em. Uel was calculated using a discrete charge theory. Kirkwood's coupling parameter method was used to calculate the excess free energy of mixing, delta GEmix, hence In gamma PS,calc. The values of In gamma PS,calc were equalized by adjusting delta Em in order to find the simulated PS/PC distribution that corresponded to the experimental results. We were thus able to compare the smeared charge calculation of [Ca2+]surf with a calculation ("masked evaluation method") that recognized clustering of the negatively charged PS: clustering was found to have a modest effect on [Ca2+]surf, relative to the smeared charge model. Even though both PS and PC tend to cluster, the long-range nature of the electrostatic repulsion reduces the extent of PS clustering at low PS mole fraction compared to PC clustering at an equivalent low PC mole fraction.

A low jitter PLL clock used for phase change memory

NASA Astrophysics Data System (ADS)

Xiao, Hong; Houpeng, Chen; Zhitang, Song; Daolin, Cai; Xi, Li

2013-02-01

A fully integrated low-jitter, precise frequency CMOS phase-locked loop (PLL) clock for the phase change memory (PCM) drive circuit is presented. The design consists of a dynamic dual-reset phase frequency detector (PFD) with high frequency acquisition, a novel low jitter charge pump, a CMOS ring oscillator based voltage-controlled oscillator (VCO), a 2nd order passive loop filter, and a digital frequency divider. The design is fabricated in 0.35 μm CMOS technology and consumes 20 mW from a supply voltage of 5 V. In terms of the PCM's program operation requirement, the output frequency range is from 1 to 140 MHz. For the 140 MHz output frequency, the circuit features a cycle-to-cycle jitter of 28 ps RMS and 250 ps peak-to-peak.

Polarization-sensitive optical coherence tomography using continuous polarization modulation with arbitrary phase modulation amplitude

NASA Astrophysics Data System (ADS)

Lu, Zenghai; Kasaragod, Deepa K.; Matcher, Stephen J.

2012-03-01

We demonstrate theoretically and experimentally that the phase retardance and relative optic-axis orientation of a sample can be calculated without prior knowledge of the actual value of the phase modulation amplitude when using a polarization-sensitive optical coherence tomography system based on continuous polarization modulation (CPM-PS-OCT). We also demonstrate that the sample Jones matrix can be calculated at any values of the phase modulation amplitude in a reasonable range depending on the system effective signal-to-noise ratio. This has fundamental importance for the development of clinical systems by simplifying the polarization modulator drive instrumentation and eliminating its calibration procedure. This was validated on measurements of a three-quarter waveplate and an equine tendon sample by a fiber-based swept-source CPM-PS-OCT system.

Partial splenectomy: A case series and systematic review of the literature

PubMed Central

Esposito, Francesco; Noviello, Adele; Moles, Nicola; Cantore, Nicola; Baiamonte, Mario; Coppola Bottazzi, Enrico; Miro, Antonio

2018-01-01

Backgrounds/Aims Partial splenectomy (PS) is a surgical option for splenic mass, in order to reduce postoperative complications and preserve the splenic function. Despite this, data in literature is still scarce. The present study aimed to reveal our recent experience and provide a comprehensive overview of the feasibility and complications related to various surgical approaches. Methods Data of patients who underwent PS, between 2014 and 2017 were retrospectively reviewed. Literature was searched for studies reporting all types of PS in adult or adolescent patients. Results Five PS were performed in our department: two (40%) by laparoscopy and three (60%) by laparotomy. Two (40%) postoperative complications were detected, and in one of them, total splenectomy (TS) by laparotomy was finally required. There were no deaths or complications at last follow-up. Twenty studies including 213 patients were identified in the literature search. The rate of conversion from laparoscopic to open surgery was 3% (range, 5–50%) and in 3% of cases (range, 7–10%) PS was converted into total TS and the overall morbidity rate was 8% (range, 5–25%). In comparison to laparotomy, the conversion rate of laparoscopic approach to TS was 3.5% (vs. 1.4%) and a morbidity rate of 9.8% (vs. 4.3%). Conclusions The present review shows that PS is a viable procedure in selected cases. The mini-invasive approach seemed to be feasible despite the presence of higher rate of complications than the open technique. In future, further studies on this topic are needed by involving more patients. Furthermore, it is proposed that the development of robotic surgery could make this approach the new gold-standard technique for spleen-preserving surgery. PMID:29896572

Generation of a Mn(IV)-Peroxo or Mn(III)-Oxo-Mn(III) Species upon Oxygenation of Mono- and Binuclear Thiolate-Ligated Mn(II) Complexes.

PubMed

Lee, Chien-Ming; Wu, Wun-Yan; Chiang, Ming-Hsi; Bohle, D Scott; Lee, Gene-Hsiang

2017-09-05

A thiolate-bridged binuclear complex [PPN] 2 [(Mn II ( TMS PS3)) 2 ] (1, PPN = bis(triphenylphosphine)iminium and TMS PS3H 3 = (2,2',2″-trimercapto-3,3',3″-tris(trimethylsilyl)triphenylphosphine)), prepared from the reaction of MnCl 2 /[PPN]Cl and Li 3 [ TMS PS3], converts into a mononuclear complex [PPN][Mn II ( TMS PS3)(DABCO)] (2) in the presence of excess amounts of DABCO (DABCO = 1,4-diazabicyclo[2.2.2]octane). Variable temperature studies of solution containing 1 and DABCO by UV-vis spectroscopy indicate that 1 and 2 exist in significant amounts in equilibrium and mononuclear 2 is favored at low temperature. Treatment of 1 or 2 with the monomeric O 2 -side-on-bound [PPN][Mn IV (O 2 )( TMS PS3)] (3) produces the mono-oxo-bridged dimer [PPN] 2 [(Mn III ( TMS PS3)) 2 (μ-O)] (4). The electrochemistry of 1 and 2 reveals anodic peak(s) for a Mn III/ Mn II redox couple at shifted potentials against Fc/Fc + , indicating that both complexes can be oxidized by dioxygen. The O 2 activation mediated by 1 and 2 is investigated in both solution and the solid state. Microcrystals of 2 rapidly react with air or dry O 2 to generate the Mn(IV)-peroxo 3 in high yield, revealing a solid-to-solid transformation and two-electron reduction of O 2 . Oxygenation of 1 or 2 in solution, however, is affected by diffusion and transient concentration of dioxygen in the two different substrates, leading to generation of 3 and 4 in variable ratios.

GPS PPP-derived precipitable water vapor retrieval based on Tm/Ps from multiple sources of meteorological data sets in China

NASA Astrophysics Data System (ADS)

Zhang, Hongxing; Yuan, Yunbin; Li, Wei; Ou, Jikun; Li, Ying; Zhang, Baocheng

2017-04-01

Weighted mean temperature (Tm) and pressure (Ps) are two parameters of great relevance to precipitable water vapor (PWV) retrieval from global positioning system (GPS) data. However, information about the Tm and Ps cannot be available for those GPS stations that are not colocated with meteorological sensors. To investigate the optimal GPS-PWV retrieval method for China, two enhanced Tm models, GM-Tm (temperature dependent) and GH-Tm (temperature independent), are developed. Additionally, the potentials of the Ps data from the two reanalysis data sets, the National Centers for Environmental Prediction (NCEP)-Department of Energy (DOE) Reanalysis II (NCEP II) and ERA-Interim, and from the empirical model GPT2w for GPS-PWV retrieval are investigated over China. To evaluate the performances of multisources Tm and Ps data for GPS-PWV retrieval, GPS data (2011-2013) collected from 22 stations of the Crustal Movement Observation Network of China (CMONOC) were processed by using the precise point positioning (PPP) technique, estimating the zenith tropospheric delay (ZTD) so as to be subsequently converted to GPS-PWV. The retrieved GPS-PWVs are compared with their counterparts derived from NCEP II and radiosonde data over China. The results show that (1) the GM-Tm model consistently shows the highest accuracy (with root mean square error of 2.3 K), and the GH-Tm model should be selected when temperature observations are not available, and that (2) the performances of Ps from NCEP II and ERA-Interim differ marginally for GPS-PWV retrieval, and significant seasonal variations are found in the agreement between the GPS-PWVs and the PWVs derived from NCEP II and radiosonde data over China.

Effect of film thickness on morphological evolution in dewetting and crystallization of polystyrene/poly(ε-caprolactone) blend films.

PubMed

Ma, Meng; He, Zhoukun; Yang, Jinghui; Chen, Feng; Wang, Ke; Zhang, Qin; Deng, Hua; Fu, Qiang

2011-11-01

In this Article, the morphological evolution in the blend thin film of polystyrene (PS)/poly(ε-caprolactone) (PCL) was investigated via mainly AFM. It was found that an enriched two-layer structure with PS at the upper layer and PCL at the bottom layer was formed during spinning coating. By changing the solution concentration, different kinds of crystal morphologies, such as finger-like, dendritic, and spherulitic-like, could be obtained at the bottom PCL layer. These different initial states led to the morphological evolution processes to be quite different from each other, so the phase separation, dewetting, and crystalline morphology of PS/PCL blend films as a function of time were studied. It was interesting to find that the morphological evolution of PS at the upper layer was largely dependent on the film thickness. For the ultrathin (15 nm) blend film, a liquid-solid/liquid-liquid dewetting-wetting process was observed, forming ribbons that rupture into discrete circular PS islands on voronoi finger-like PCL crystal. For the thick (30 nm) blend film, the liquid-liquid dewetting of the upper PS layer from the underlying adsorbed PCL layer was found, forming interconnected rim structures that rupture into discrete circular PS islands embedded in the single lamellar PCL dendritic crystal due to Rayleigh instability. For the thicker (60 nm) blend film, a two-step liquid-liquid dewetting process with regular holes decorated with dendritic PCL crystal at early annealing stage and small holes decorated with spherulite-like PCL crystal among the early dewetting holes at later annealing stage was observed. The mechanism of this unusual morphological evolution process was discussed on the basis of the entropy effect and annealing-induced phase separation.

Polymer blend lithography: A versatile method to fabricate nanopatterned self-assembled monolayers.

PubMed

Huang, Cheng; Moosmann, Markus; Jin, Jiehong; Heiler, Tobias; Walheim, Stefan; Schimmel, Thomas

2012-01-01

A rapid and cost-effective lithographic method, polymer blend lithography (PBL), is reported to produce patterned self-assembled monolayers (SAM) on solid substrates featuring two or three different chemical functionalities. For the pattern generation we use the phase separation of two immiscible polymers in a blend solution during a spin-coating process. By controlling the spin-coating parameters and conditions, including the ambient atmosphere (humidity), the molar mass of the polystyrene (PS) and poly(methyl methacrylate) (PMMA), and the mass ratio between the two polymers in the blend solution, the formation of a purely lateral morphology (PS islands standing on the substrate while isolated in the PMMA matrix) can be reproducibly induced. Either of the formed phases (PS or PMMA) can be selectively dissolved afterwards, and the remaining phase can be used as a lift-off mask for the formation of a nanopatterned functional silane monolayer. This "monolayer copy" of the polymer phase morphology has a topographic contrast of about 1.3 nm. A demonstration of tuning of the PS island diameter is given by changing the molar mass of PS. Moreover, polymer blend lithography can provide the possibility of fabricating a surface with three different chemical components: This is demonstrated by inducing breath figures (evaporated condensed entity) at higher humidity during the spin-coating process. Here we demonstrate the formation of a lateral pattern consisting of regions covered with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS) and (3-aminopropyl)triethoxysilane (APTES), and at the same time featuring regions of bare SiO(x). The patterning process could be applied even on meter-sized substrates with various functional SAM molecules, making this process suitable for the rapid preparation of quasi two-dimensional nanopatterned functional substrates, e.g., for the template-controlled growth of ZnO nanostructures [1].

Structural, Optical and Electrical Properties of ZnS/Porous Silicon Heterostructures

NASA Astrophysics Data System (ADS)

Wang, Cai-Feng; Li, Qing-Shan; Lv, Lei; Zhang, Li-Chun; Qi, Hong-Xia; Chen, Hou

2007-03-01

ZnS films are deposited by pulsed laser deposition on porous silicon (PS) substrates formed by electrochemical anodization of p-type (100) silicon wafer. Scanning electron microscope images reveal that the surface of ZnS films is unsmoothed, and there are some cracks in the ZnS films due to the roughness of the PS surface. The x-ray diffraction patterns show that the ZnS films on PS surface are grown in preferring orientation along cubic phase β-ZnS (111) direction. White light emission is obtained by combining the blue-green emission from ZnS films with the orange-red emission from PS layers. Based on the I-V characteristic, the ZnS/PS heterojunction exhibits the rectifying junction behaviour, and an ideality factor n is calculated to be 77 from the I-V plot.

Local Wave Propagation and Crustal Structure Tomography in Northern Mississippi Embayment

NASA Astrophysics Data System (ADS)

Yang, Y.; Langston, C. A.

2016-12-01

Several datasets in the vicinity of the New Madrid Seismic Zone (NMSZ) are used to study local wave propagation and crustal structure in this region, including data collected for the Northern Embayment Lithosphere Experiment (NELE) project, Transportable Array, New Madrid Cooperative Network and Embayment Seismic Excitation Experiment (ESEE). Focal mechanisms and focal depths are determined with the help of synthetic seismograms for earthquakes with magnitude larger than 3. The thick unconsolidated sediment complicates waveforms inside the Mississippi Embayment by producing large converted PS, SP phases and reverberations that mask important near-source depth phases. Modeling events with well-constrained focal mechanisms using synthetic seismograms reveals a variety of waveguide propagation effects including P and S sediment reverberations as well as leaky mode P wave trains. Substantial differences in the travel time of the mid-crustal reflection are observed for waves traveling in different directions. The travel time of the mid-crustal reflection waves and direct waves are then used in a tomography for the crustal structure. The result reveals that there is a significant southwest dip to the top of the mid-crust in the vicinity of the NMSZ. Resulting image and the determined source parameters are essential for full waveform inversion to determine high-resolution crustal structure of the Northern Mississippi Embayment.

DC/DC Converter Stability Testing Study

NASA Technical Reports Server (NTRS)

Wang, Bright L.

2008-01-01

This report presents study results on hybrid DC/DC converter stability testing methods. An input impedance measurement method and a gain/phase margin measurement method were evaluated to be effective to determine front-end oscillation and feedback loop oscillation. In particular, certain channel power levels of converter input noises have been found to have high degree correlation with the gain/phase margins. It becomes a potential new method to evaluate stability levels of all type of DC/DC converters by utilizing the spectral analysis on converter input noises.

Use of a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin column and propionic acid as an eluent in ion-exclusion/adsorption chromatography of aliphatic carboxylic acids and ethanol in food samples.

PubMed

Mori, Masanobu; Hironaga, Takahiro; Kajiwara, Hiroe; Nakatani, Nobutake; Kozaki, Daisuke; Itabashi, Hideyuki; Tanaka, Kazuhiko

2011-01-01

We developed an ion-exclusion/adsorption chromatography (IEAC) method employing a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin (PS-WCX) column with propionic acid as the eluent for the simultaneous determination of multivalent aliphatic carboxylic acids and ethanol in food samples. The PS-WCX column well resolved mono-, di-, and trivalent carboxylic acids in the acidic eluent. Propionic acid as the eluent gave a higher signal-to-noise ratio, and enabled sensitive conductimetric detection of analyte acids. We found the optimal separation condition to be the combination of a PS-WCX column and 20-mM propionic acid. Practical applicability of the developed method was confirmed by using a short precolumn with a strongly acidic cation-exchange resin in the H(+)-form connected before the separation column; this was to remove cations from food samples by converting them to hydrogen ions. Consequently, common carboxylic acids and ethanol in beer, wine, and soy sauce were successfully separated by the developed method.

The indirect costs of psoriatic arthritis: systematic review and meta-analysis.

PubMed

Kawalec, Paweł; Malinowski, Krzysztof Piotr

2015-02-01

The aim of this systematic review is to collect all current data on the indirect costs (IC) related to psoriatic arthritis (PsA). The search was conducted using MEDLINE (via PubMed), Embase and Centre for Reviews and Dissemination databases. We considered original studies, systematic reviews, economic evaluations, conference abstracts and posters. All collected data were recalculated to average annual cost per patient, expressed using the consumer price index for 2013 and converted to US dollars using purchasing power parity. Eight of the identified publications presented IC of PsA. Average annual IC per patient calculated using the friction cost approach range from US$1693.83 to $12,318.45, while using the human capital approach they range from US$1750.68 to $50,270.52. Result of the meta-analysis was a basis for calculating cost of work disability equaled US$10,754.04 per patient per year in 2013 prices. This systematic review revealed a great economic burden of the disease to the society. A small number of studies on IC in PsA justify further investigations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Ke; Li Yanqiu; Wang Hai

Characterization of measurement accuracy of the phase-shifting point diffraction interferometer (PS/PDI) is usually performed by two-pinhole null test. In this procedure, the geometrical coma and detector tilt astigmatism systematic errors are almost one or two magnitude higher than the desired accuracy of PS/PDI. These errors must be accurately removed from the null test result to achieve high accuracy. Published calibration methods, which can remove the geometrical coma error successfully, have some limitations in calibrating the astigmatism error. In this paper, we propose a method to simultaneously calibrate the geometrical coma and detector tilt astigmatism errors in PS/PDI null test. Basedmore » on the measurement results obtained from two pinhole pairs in orthogonal directions, the method utilizes the orthogonal and rotational symmetry properties of Zernike polynomials over unit circle to calculate the systematic errors introduced in null test of PS/PDI. The experiment using PS/PDI operated at visible light is performed to verify the method. The results show that the method is effective in isolating the systematic errors of PS/PDI and the measurement accuracy of the calibrated PS/PDI is 0.0088{lambda} rms ({lambda}= 632.8 nm).« less

Photosystem I assembly on chemically tailored SAM/ Au substrates for bio-hybrid device fabrication

NASA Astrophysics Data System (ADS)

Mukherjee, Dibyendu; Khomami, Bamin

2011-03-01

Photosystem I (PS I), a supra-molecular protein complex and a biological photodiode responsible for driving natural photosynthesis mechanism, charge separates upon exposure to light. Effective use of the photo-electrochemical activities of PS I for future bio-hybrid electronic devices requires controlled attachment of these proteins onto organic/ inorganic substrates. Our results indicate that various experimental parameters alter the surface topography of PS I deposited from colloidal aqueous buffer suspensions onto OH-terminated alkanethiolate SAM /Au substrates, thereby resulting in complex columnar structures that affect the electron capture pathway of PS I. Specifically, solution phase characterizations indicate that specific detergents used for PS I stabilization in buffer solutions drive the unique colloidal chemistry to tune protein-protein interactions and prevent aggregation, thereby allowing us to tailor the morphology of surface immobilized PS I. We present surface topographical, adsorption, and electrochemical characterizations of PSI /SAM/Au substrates to elucidate protein-surface attachment dynamics and its effect on the photo-activated electronic activities of surface immobilized PS I. Sustainable Energy Education and Research Center (SEERC).

First Principles Calculations of Transition Metal Binary Alloys: Phase Stability and Surface Effects

NASA Astrophysics Data System (ADS)

Aspera, Susan Meñez; Arevalo, Ryan Lacdao; Shimizu, Koji; Kishida, Ryo; Kojima, Kazuki; Linh, Nguyen Hoang; Nakanishi, Hiroshi; Kasai, Hideaki

2017-06-01

The phase stability and surface effects on binary transition metal nano-alloy systems were investigated using density functional theory-based first principles calculations. In this study, we evaluated the cohesive and alloying energies of six binary metal alloy bulk systems that sample each type of alloys according to miscibility, i.e., Au-Ag and Pd-Ag for the solid solution-type alloys (SS), Pd-Ir and Pd-Rh for the high-temperature solid solution-type alloys (HTSS), and Au-Ir and Ag-Rh for the phase-separation (PS)-type alloys. Our results and analysis show consistency with experimental observations on the type of materials in the bulk phase. Varying the lattice parameter was also shown to have an effect on the stability of the bulk mixed alloy system. It was observed, particularly for the PS- and HTSS-type materials, that mixing gains energy from the increasing lattice constant. We furthermore evaluated the surface effects, which is an important factor to consider for nanoparticle-sized alloys, through analysis of the (001) and (111) surface facets. We found that the stability of the surface depends on the optimization of atomic positions and segregation of atoms near/at the surface, particularly for the HTSS and the PS types of metal alloys. Furthermore, the increase in energy for mixing atoms at the interface of the atomic boundaries of PS- and HTSS-type materials is low enough to overcome by the gain in energy through entropy. These, therefore, are the main proponents for the possibility of mixing alloys near the surface.

The National Cancer Institute's Physical Sciences - Oncology Network

NASA Astrophysics Data System (ADS)

Espey, Michael Graham

In 2009, the NCI launched the Physical Sciences - Oncology Centers (PS-OC) initiative with 12 Centers (U54) funded through 2014. The current phase of the Program includes U54 funded Centers with the added feature of soliciting new Physical Science - Oncology Projects (PS-OP) U01 grant applications through 2017; see NCI PAR-15-021. The PS-OPs, individually and along with other PS-OPs and the Physical Sciences-Oncology Centers (PS-OCs), comprise the Physical Sciences-Oncology Network (PS-ON). The foundation of the Physical Sciences-Oncology initiative is a high-risk, high-reward program that promotes a `physical sciences perspective' of cancer and fosters the convergence of physical science and cancer research by forming transdisciplinary teams of physical scientists (e.g., physicists, mathematicians, chemists, engineers, computer scientists) and cancer researchers (e.g., cancer biologists, oncologists, pathologists) who work closely together to advance our understanding of cancer. The collaborative PS-ON structure catalyzes transformative science through increased exchange of people, ideas, and approaches. PS-ON resources are leveraged to fund Trans-Network pilot projects to enable synergy and cross-testing of experimental and/or theoretical concepts. This session will include a brief PS-ON overview followed by a strategic discussion with the APS community to exchange perspectives on the progression of trans-disciplinary physical sciences in cancer research.

Cerebrovascular aspects of converting-enzyme inhibition II: Blood-brain barrier permeability and effect of intracerebroventricular administration of captopril.

PubMed

Jarden, J O; Barry, D I; Juhler, M; Graham, D I; Strandgaard, S; Paulson, O B

1984-12-01

The blood-brain barrier permeability to captopril, and the cerebrovascular effects of intracerebroventricular administration of captopril, were studied in normotensive Wistar rats. The blood-brain barrier permeability-surface area product (PS), determined by an integral-uptake method, was about 1 X 10(-5) cm3/g/s in all brain regions studied. This was three to four times lower than the simultaneously determined PS of Na+ and Cl-, both of which are known to have very low blood-brain barrier permeability. Cerebral blood flow, determined by the intra-arterial 133xenon injection method, was unaffected by intracerebroventricular administration of 100 micrograms captopril. Furthermore the lower limit of cerebral blood flow autoregulation during haemorrhagic hypotension was also unaffected, being in the mean arterial pressure range (50-69 mmHg) in both controls and captopril-treated rats. It was concluded that the blood-brain barrier permeability of captopril was negligible and that inhibition of the brain renin-angiotensin system has no effect on global cerebral blood flow. The cerebrovascular effects of intravenously administered captopril (a resetting to lower pressure of the limits and range of cerebral blood flow autoregulation) are probably exerted via converting enzyme on the luminal surface of cerebral vessels.

Upcycling : converting waste plastics into paramagnetic, conducting, solid, pure carbon microspheres.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pol, V.

2010-06-15

The recent tremendous increase in the volume of waste plastics (WP) will have a harmful environmental impact on the health of living beings. Hundreds of years are required to degrade WP in atmospheric conditions. Hence, in coming years, in addition to traditional recycling services, innovative 'upcycling' processes are necessary. This article presents an environmentally benign, solvent-free autogenic process that converts various WP [low density polyethylene (LDPE), high density polyethylene (HDPE), polyethylene terephthalate (PET), polystyrene (PS), or their mixtures] into carbon microspheres (CMSs), an industrially significant, value-added product. The thermal dissociation of these individual or mixed WP in a closed reactormore » under autogenic pressure (1000 psi) produced dry, pure powder of CMSs. In this paper, the optimization of process parameters such as the effect of mixing of WP with other materials, and the role of reaction temperature and time are reported. Employing advanced analytical techniques, the atomic structure, composition, and morphology of as-obtained CMSs were analyzed. The room-temperature paramagnetism in CMSs prepared from waste LDPE, HDPE, and PS was further studied by electron paramagnetic resonance (EPR). The conducting and paramagnetic nature of CMSs holds promise for their potential applications in toners, printers, paints, batteries, lubricants, and tires.« less

Tunable PhoXonic Band Gap Materials from Self-Assembly of Block Copoliymers and Colloidal Nanocrystals (NBIT Phase II)

DTIC Science & Technology

2011-05-06

electric fields. For that, we are going to use PS - b - P2VP block copolymers as a model system, utilizing the quite versatile chemistry of the P2VP ...displays. Our efforts at Hanyang have focused on tunable PBG materials self-assembled from polystyrene- b -poly(2-vinyl pyridine) ( PS - b - P2VP ) block...small angle x-ray scattering measurements during swelling of low molecular weight PS - P2VP polymers at the Cornell High Energy Synchrotron Source

P-S & S-P Elastic Wave Conversions from Linear Arrays of Oriented Microcracks

NASA Astrophysics Data System (ADS)

Jiang, L.; Modiriasari, A.; Bobet, A.; Pyrak-Nolte, L. J.

2017-12-01

Natural and induced processes can produce oriented mechanical discontinuities such as en echelon cracks, fractures and faults. Previous research has shown that compressional to shear (P-S) wave conversions occur at normal incidence to a fracture because of cross-coupling fracture compliances (Nakagawa et al., 2000). Here, experiments and computer simulation are presented to demonstrate the link among cross-coupling stiffness, microcrack orientation and energy partitioning among P, S, and P-S/S-P waves. A FormLabs 2 3D printer was used to fabricate 7 samples (50 mm x 50 mm x 100 mm) with linear arrays of microcracks oriented at 0, 15, 30, 45, 60, 75, and 900 with a print resolution of 0.025 mm. The microcracks were elliptical in cross-sections (2 mm long by 1 mm wide), through the 50 mm thickness of sample, and spaced 3 mm (center-to-center for adjacent cracks). A 25 mm length of each sample contained no microcracks to act as a reference material. Broadband transducers (0.2-1.5 MHz) were used to transmit and receive P and polarized S wave signals that were propagated at normal incidence to the linear array of microcracks. P-wave amplitude increased, while S-wave amplitude remained relatively constant, as the microcrack orientation increased from 0o to 90o. At normal incidence, P-S and S-P wave conversions emerged and increased in amplitude as the crack inclination increased from 00 to 450. From 450 to 900, the amplitude of these converted modes decreased. Between negative and positive crack angles, the P-to-S and S-to-P waves were 1800 phase reversed. The observed energy partitioning matched the computed compliances obtained from numerical simulations with ABAQUS. The cross-coupling compliance for cracks inclined at 450 was found to be the smallest magnitude. 3D printing enabled the study of microstructural effects on macro-scale wave measurements. Information on the orientation of microcracks or even en echelon fractures and faults is contained in P-S conversions even at normal incidence. Acknowledgment: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Research Program under Award Number (DE-FG02-09ER16022) and by the National Science Foundation, Geomechanics and Geotechnical Systems Program (award No. CMMI-1162082).

Structure of the Upper Mantle and Mantle Transition Zone in Central Mongolia

NASA Astrophysics Data System (ADS)

Cui, Z.; Meltzer, A.; Stachnik, J.; Fischer, K. M.; Russo, R. M.; Munkhuu, U.; Baasanbat, T.

2016-12-01

Located between two major Archean cratons, the Siberian Craton to the north and the Tarim and Sino-Korean Cratons to the south, the lithosphere of Central Mongolia was constructed over an extended period of orogenesis associated with the Central Asian Orogenic Belt. Archean to Early Proterozoic basement was modified by accreted subduction complexes during the Paleozoic and early Mesozoic and basalt magmatism in the Cenozoic. Central and western Mongolia constitute a significant portion of the greater Mongolian plateau, an approximately 2.6 million km2area of Central Asia with an average elevation of 1500 meters. The high topography of the Mongolian Plateau has been attributed to far-field effects of India-Asia convergence, Pacific plate subduction, mantle plume activity, convective mantle flow, and magmatic underplating. The origin and persistence of continental plateaus through time provides insight into the evolution of continents and interactions between mantle dynamics and surface processes. As part of a larger interdisciplinary project to understand the origin of high topography in continental interiors we deployed 112 seismic broadband stations in central Mongolia as three separate subarrays in two separate mobilizations over a four year period (2012-2016). The stations extend from the Hovsgol rift in northern Mongolia, through the Hangay Dome, and into the Gobi Altai in southern Mongolia. We use S wave Receiver functions (SRF) to examine the lithosphere asthenosphere boundary and P wave Receiver functions (PRF) to investigate the mantle transition zone (MTZ). Preliminary SRF results from the subarray in the Hangay show lithospheric thinning and E-W variation. The LAB beneath the Hangay is 100km. It gradually thins to 90 km at the western end of the central Hangay and thins more abruptly to 80km at the eastern end of the central Hangay. These results are in agreement with results from joint inversion of receiver functions and surface waves and teleseismic tomography. PRF exhibit a clear Ps arrival from the 410-km discontinuity but a weak Ps phase converted from 660-km discontinuity in both station and CCP stacks. The 410-km Ps arrival is gradually delayed from south to north corresponding to a depth change of 20km. Several stations with visible 660-km Ps suggest a 10-30 km thinning within the MTZ.

Comparative study on the roles of anisotropic epitaxial strain and chemical doping in inducing the antiferromagnetic insulator phase in manganite films

NASA Astrophysics Data System (ADS)

Jin, Feng; Feng, Qiyuan; Guo, Zhuang; Lan, Da; Wang, Lingfei; Gao, Guanyin; Xu, Haoran; Chen, Binbin; Chen, Feng; Lu, Qingyou; Wu, Wenbin

2017-11-01

Epitaxial strain and chemical doping are two different methods that are commonly used to tune the physical properties of epitaxial perovskite oxide films, but their cooperative effects are less addressed. Here we try to tune the phase separation (PS) in (La1-xP rx) 2 /3C a1 /3Mn O3 (0 ≤x ≤0.4 , LPCMO) films via cooperatively controlling the anisotropic epitaxial strain (AES) and the Pr doping. These films are grown simultaneously on NdGa O3(110 ) ,(LaAlO3) 0.3(SrAl0.5Ta0.5O3 ) 0.7(001 ) , and NdGa O3(001 ) substrates with progressively increased in-plane AES, and probed by x-ray diffraction, magnetotransport, and magnetic force microscopy (MFM) measurements. Although it is known that for x =0 the AES can enhance the orthorhombicity of the films yielding a phase diagram with the antiferromagnetic charge-ordered insulator (AF-COI) state induced, which is quite different from the bulk one, we illustrate that the Pr doping can further drive the films towards a more robust COI state. This cooperative effect is reflected by the increasing magnetic fields needed to melt the COI phase as a function of AES and the doping level. More strikingly, by directly imaging the phase competition morphology of the LPCMO /NdGa O3(001 ) films via MFM, we find that during COI melting the PS domain structure is subject to both AES and the quenched disorder. However, in the reverse process, as the magnetic field is decreased, the COI phase reappears and the AES dominates leaving a crystalline-orientation determined self-organized microstructure. This finding suggests that the PS states and the domain configurations can be selectively controlled by the AES and/or the quenched disorder, which may shed some light on the engineering of PS domains for device fabrications.

Single-shot gas-phase thermometry using pure-rotational hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering.

PubMed

Miller, Joseph D; Roy, Sukesh; Slipchenko, Mikhail N; Gord, James R; Meyer, Terrence R

2011-08-01

High-repetition-rate, single-laser-shot measurements are important for the investigation of unsteady flows where temperature and species concentrations can vary significantly. Here, we demonstrate single-shot, pure-rotational, hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps RCARS) thermometry based on a kHz-rate fs laser source. Interferences that can affect nanosecond (ns) and ps CARS, such as nonresonant background and collisional dephasing, are eliminated by selecting an appropriate time delay between the 100-fs pump/Stokes pulses and the pulse-shaped 8.4-ps probe. A time- and frequency-domain theoretical model is introduced to account for rotational-level dependent collisional dephasing and indicates that the optimal probe-pulse time delay is 13.5 ps to 30 ps. This time delay allows for uncorrected best-fit N2-RCARS temperature measurements with ~1% accuracy. Hence, the hybrid fs/ps RCARS approach can be performed with kHz-rate laser sources while avoiding corrections that can be difficult to predict in unsteady flows.

Single-shot gas-phase thermometry using pure-rotational hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering

NASA Astrophysics Data System (ADS)

Miller, Joseph D.; Roy, Sukesh; Slipchenko, Mikhail N.; Gord, James R.; Meyer, Terrence R.

2011-08-01

High-repetition-rate, single-laser-shot measurements are important for the investigation of unsteady flows where temperature and species concentrations can vary significantly. Here, we demonstrate single-shot, pure-rotational, hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps RCARS) thermometry based on a kHz-rate fs laser source. Interferences that can affect nanosecond (ns) and ps CARS, such as nonresonant background and collisional dephasing, are eliminated by selecting an appropriate time delay between the 100-fs pump/Stokes pulses and the pulse-shaped 8.4-ps probe. A time- and frequency-domain theoretical model is introduced to account for rotational-level dependent collisional dephasing and indicates that the optimal probe-pulse time delay is 13.5 ps to 30 ps. This time delay allows for uncorrected best-fit N2-RCARS temperature measurements with ~1% accuracy. Hence, the hybrid fs/ps RCARS approach can be performed with kHz-rate laser sources while avoiding corrections that can be difficult to predict in unsteady flows.

A Model of Cancer Stem Cells Derived from Mouse Induced Pluripotent Stem Cells

PubMed Central

Chen, Ling; Kasai, Tomonari; Li, Yueguang; Sugii, Yuh; Jin, Guoliang; Okada, Masashi; Vaidyanath, Arun; Mizutani, Akifumi; Satoh, Ayano; Kudoh, Takayuki; Hendrix, Mary J. C.; Salomon, David S.; Fu, Li; Seno, Masaharu

2012-01-01

Cancer stem cells (CSCs) are capable of continuous proliferation and self-renewal and are proposed to play significant roles in oncogenesis, tumor growth, metastasis and cancer recurrence. CSCs are considered derived from normal stem cells affected by the tumor microenvironment although the mechanism of development is not clear yet. In 2007, Yamanaka's group succeeded in generating Nanog mouse induced pluripotent stem (miPS) cells, in which green fluorescent protein (GFP) has been inserted into the 5′-untranslated region of the Nanog gene. Usually, iPS cells, just like embryonic stem cells, are considered to be induced into progenitor cells, which differentiate into various normal phenotypes depending on the normal niche. We hypothesized that CSCs could be derived from Nanog miPS cells in the conditioned culture medium of cancer cell lines, which is a mimic of carcinoma microenvironment. As a result, the Nanog miPS cells treated with the conditioned medium of mouse Lewis lung carcinoma acquired characteristics of CSCs, in that they formed spheroids expressing GFP in suspension culture, and had a high tumorigenicity in Balb/c nude mice exhibiting angiogenesis in vivo. In addition, these iPS-derived CSCs had a capacity of self-renewal and expressed the marker genes, Nanog, Rex1, Eras, Esg1 and Cripto, associated with stem cell properties and an undifferentiated state. Thus we concluded that a model of CSCs was originally developed from miPS cells and proposed the conditioned culture medium of cancer cell lines might perform as niche for producing CSCs. The model of CSCs and the procedure of their establishment will help study the genetic alterations and the secreted factors in the tumor microenvironment which convert miPS cells to CSCs. Furthermore, the identification of potentially bona fide markers of CSCs, which will help the development of novel anti-cancer therapies, might be possible though the CSC model. PMID:22511923

Characterization of Cancer Stem-Like Cells Derived from Mouse Induced Pluripotent Stem Cells Transformed by Tumor-Derived Extracellular Vesicles

PubMed Central

Yan, Ting; Mizutani, Akifumi; Chen, Ling; Takaki, Mai; Hiramoto, Yuki; Matsuda, Shuichi; Shigehiro, Tsukasa; Kasai, Tomonari; Kudoh, Takayuki; Murakami, Hiroshi; Masuda, Junko; Hendrix, Mary J. C.; Strizzi, Luigi; Salomon, David S.; Fu, Li; Seno, Masaharu

2014-01-01

Several studies have shown that cancer niche can perform an active role in the regulation of tumor cell maintenance and progression through extracellular vesicles-based intercellular communication. However, it has not been reported whether this vesicle-mediated communication affects the malignant transformation of normal stem cells/progenitors. We have previously reported that the conditioned medium derived from the mouse Lewis Lung Carcinoma (LLC) cell line can convert mouse induced pluripotent stem cells (miPSCs) into cancer stem cells (CSCs), indicating that normal stem cells when placed in an aberrant microenvironment can give rise to functionally active CSCs. Here, we focused on the contribution of tumor-derived extracellular vesicles (tEVs) that are secreted from LLC cells to induce the transformation of miPSCs into CSCs. We isolated tEVs from the conditioned medium of LLC cells, and then the differentiating miPSCs were exposed to tEVs for 4 weeks. The resultant tEV treated cells (miPS-LLCev) expressed Nanog and Oct3/4 proteins comparable to miPSCs. The frequency of sphere formation of the miPS-LLCev cells in suspension culture indicated that the self-renewal capacity of the miPS-LLCev cells was significant. When the miPS-LLCev cells were subcutaneously transplanted into Balb/c nude mice, malignant liposarcomas with extensive angiogenesis developed. miPS-LLCevPT and miPS-LLCevDT, the cells established from primary site and disseminated liposarcomas, respectively, showed their capacities to self-renew and differentiate into adipocytes and endothelial cells. Moreover, we confirmed the secondary liposarcoma development when these cells were transplanted. Taken together, these results indicate that miPS-LLCev cells possess CSC properties. Thus, our current study provides the first evidence that tEVs have the potential to induce CSC properties in normal tissue stem cells/progenitors. PMID:25057308

Synchronization Tomography: Modeling and Exploring Complex Brain Dynamics

NASA Astrophysics Data System (ADS)

Fieseler, Thomas

2002-03-01

Phase synchronization (PS) plays an important role both under physiological and pathological conditions. With standard averaging techniques of MEG data, it is difficult to reliably detect cortico-cortical and cortico-muscular PS processes that are not time-locked to an external stimulus. For this reason, novel synchronization analysis techniques were developed and directly applied to MEG signals. Of course, due to the lack of an inverse modeling (i.e. source localization), the spatial resolution of this approach was limited. To detect and localize cerebral PS, we here present the synchronization tomography (ST): For this, we first estimate the cerebral current source density by means of the magnetic field tomography (MFT). We then apply the single-run PS analysis to the current source density in each voxel of the reconstruction space. In this way we study simulated PS, voxel by voxel in order to determine the spatio-temporal resolution of the ST. To this end different generators of ongoing rhythmic cerebral activity are simulated by current dipoles at different locations and directions, which are modeled by slightly detuned chaotic oscillators. MEG signals for these generators are simulated for a spherical head model and a whole-head MEG system. MFT current density solutions are calculated from these simulated signals within a hemispherical source space. We compare the spatial resolution of the ST with that of the MFT. Our results show that adjacent sources which are indistinguishable for the MFT, can nevertheless be separated with the ST, provided they are not strongly phase synchronized. This clearly demonstrates the potential of combining spatial information (i.e. source localization) with temporal information for the anatomical localization of phase synchronization in the human brain.

Interleaved power converter

DOEpatents

Zhu, Lizhi

2007-11-13

A power converter architecture interleaves full bridge converters to alleviate thermal management problems in high current applications, and may, for example, double the output power capability while reducing parts count and costs. For example, one phase of a three phase inverter is shared between two transformers, which provide power to a rectifier such as a current doubler rectifier to provide two full bridge DC/DC converters with three rather than four high voltage inverter legs.

Separation and determination of minor photosynthetic pigments by reversed-phase HPLC with minimal alteration of chlorophylls.

PubMed

Nakamura, A; Watanabe, T

2001-04-01

Reversed-phase HPLC conditions for separation of chlorophyll (Chl) a, Chl a' (the C132-epimer of Chl a), pheophytin (Pheo) a (the primary electron acceptor of photosystem (PS) II), and phylloquinone (PhQ) (the secondary electron acceptor of PS 1), have been developed. Pigment extraction conditions were optimized in terms of pigment alteration and extraction efficiency. Pigment composition analysis of light-harvesting complex II, which would not contain Chl a' nor Pheo a, showed the Chl a'/Chl a ratio of 3-4 x 10(-4) and the Pheo a/Chl a ratio of 4-5 x 10(-4), showing that the conditions developed here were sufficiently inert for Chl analysis. Preliminary analysis of thylakoid membranes with this analytical system gave the PhQ/Chl a' ratio of 0.58 +/- 0.03 (n = 4), in line with the stoichiometry of one molecule of Chl a' per PS I.

Phase diagram of the Hubbard-Holstein model on a four-leg tube system at quarter filling

NASA Astrophysics Data System (ADS)

Reja, Sahinur; Nishimoto, Satoshi

2018-06-01

We derive an effective electronic Hamiltonian for the square lattice Hubbard-Holstein model (HHM) in the strong electron-electron (e -e ) and electron-phonon (e -p h ) coupling regime and under nonadiabatic conditions (t /ω0≤1 ), t and ω0 being the electron hopping and phonon frequency respectively. Using the density matrix renormalization-group method, we simulate this effective electronic model on a four-leg cylinder system at quarter filling and present a phase diagram in the g -U plane where g and U are the e -p h coupling constant and Hubbard on-site interaction respectively. For larger g , we find that a cluster of spins, i.e., phase separation (PS), gives way to a charge density wave (CDW) phase made of nearest-neighbor singlets which abruptly goes to another CDW phase as we increase U . But for smaller g , we find a metallic phase sandwiched between PS and the singlet CDW phase. This phase is characterized by a vanishing charge gap but a finite spin gap, suggesting a singlet superconducting phase.

Versatile all-digital time interval measuring system

NASA Astrophysics Data System (ADS)

Vyhlidal, David; Cech, Miroslav

2011-06-01

This paper describes a design and performance of a versatile all-digital time interval measuring system. The measurement method is based on an interpolation principle. In this principle the time interval is first roughly digitized by a coarse counter driven by a high stability reference clock and the fractions between the clock periods are measured by two Time-to-Digital Converter chips TDC-GPX manufactured by Acam messelectronic. Control circuits allow programmable customization of the system to satisfy many applications such as laser range finding, event counting, or time-of-flight measurements in various physics experiments. The system has two reference clocks inputs and two independent channels for measuring start and stop events. Only one 40 MHz reference is required for the measurement. The second reference can be, for example, 1 PPS (Pulse per Second) signal from a GPS (Global Positioning System) to time tag events. Time intervals are measured using the highest resolution mode of the TDC-GPX chips. The resolution of each chip is software programmable and is PLL (Phase Locked Loop) stabilized against temperature and voltage variations. The system can achieve a timing resolution better than 15 ps rms with up to 90 kHz repetition rate. The time interval measurement range is from 0 ps up to 1 second. The power consumption of the whole system is 18 W including an embedded computer board and an LCD (Liquid Crystal Display) screen. The embedded computer controls the whole system, collects and evaluates measurement data and with the display provides a user interface. The system is implemented using commercially available components.

Nonlinear mirror modelocking of a bounce geometry laser.

PubMed

Thomas, G M; Bäuerle, A; Farrell, D J; Damzen, M J

2010-06-07

We present the investigation of nonlinear mirror modelocking (NLM) of a bounce amplifier laser. This technique, a potential rival to SESAM modelocking, uses a nonlinear crystal and a dichroic mirror to passively modelock a Nd:GdVO(4) slab bounce amplifier operating at 1063nm. At 11.3W, we present the highest power achieved using the NLM technique, using type-II phase-matched KTP, with a pulse duration of 57ps. Using type-I phase-matched BiBO, modelocking was achieved with a shorter pulse duration of 5.7ps at an average power of 7.1W.

Polarization-sensitive optical coherence tomography measurements with different phase modulation amplitude when using continuous polarization modulation

NASA Astrophysics Data System (ADS)

Lu, Zenghai; Kasaragod, Deepa K.; Matcher, Stephen J.

2012-01-01

We demonstrate theoretically and experimentally that the phase retardance and relative optic-axis orientation of a sample can be calculated without prior knowledge of the actual value of the phase modulation amplitude when using a polarization-sensitive optical coherence tomography system based on continuous polarization modulation (CPM-PS-OCT). We also demonstrate that the sample Jones matrix can be calculated at any values of the phase modulation amplitude in a reasonable range depending on the system effective signal-to-noise ratio. This has fundamental importance for the development of clinical systems by simplifying the polarization modulator drive instrumentation and eliminating its calibration procedure. This was validated on measurements of a three-quarter waveplate and an equine tendon sample by a fiber-based swept-source CPM-PS-OCT system.

Synthesis of porous poly(styrene-co-acrylic acid) microspheres through one-step soap-free emulsion polymerization: whys and wherefores.

PubMed

Yan, Rui; Zhang, Yaoyao; Wang, Xiaohui; Xu, Jianxiong; Wang, Da; Zhang, Wangqing

2012-02-15

Synthesis of porous poly(styrene-co-acrylic acid) (PS-co-PAA) microspheres through one-step soap-free emulsion polymerization is reported. Various porous PS-co-PAA microspheres with the particle size ranging from 150 to 240 nm and with the pore size ranging from 4 to 25 nm are fabricated. The porous structure of the microspheres is confirmed by the transmission electron microscopy measurement and Brunauer-Emmett-Teller (BET) analysis. The reason for synthesis of the porous PS-co-PAA microspheres is discussed, and the phase separation between the encapsulated hydrophilic poly(acrylic acid) segment and the hydrophobic polystyrene domain within the PS-co-PAA microspheres is ascribed to the pore formation. The present synthesis of the porous PS-co-PAA microspheres is anticipated to be a new and convenient way to fabricate porous polymeric particles. Copyright © 2011 Elsevier Inc. All rights reserved.

Growing evidence that SNe Iax are not a one-parameter family. The case of PS1-12bwh

NASA Astrophysics Data System (ADS)

Magee, M. R.; Kotak, R.; Sim, S. A.; Wright, D.; Smartt, S. J.; Berger, E.; Chornock, R.; Foley, R. J.; Howell, D. A.; Kaiser, N.; Magnier, E. A.; Wainscoat, R.; Waters, C.

2017-05-01

In this study, we present observations of a type Iax supernova, PS1-12bwh, discovered during the Pan-STARRS1 3π-survey. Our analysis was driven by previously unseen pre-maximum, spectroscopic heterogeneity. While the light curve and post-maximum spectra of PS1-12bwh are virtually identical to those of the well-studied type Iax supernova, SN 2005hk, the -2 day spectrum of PS1-12bwh does not resemble SN 2005hk at a comparable epoch; instead, we found it to match a spectrum of SN 2005hk taken over a week earlier (-12 day). We are able to rule out the cause as being incorrect phasing, and argue that it is not consistent with orientation effects predicted by existing explosion simulations. To investigate the potential source of this difference, we performed radiative transfer modelling of both supernovae. We found that the pre-maximum spectrum of PS1-12bwh is well matched by a synthetic spectrum generated from a model with a lower density in the high velocity (≳6000 km s-1) ejecta than SN 2005hk. The observed differences between SN 2005hk and PS1-12bwh may therefore be attributed primarily to differences in the high velocity ejecta alone, while comparable densities for the lower velocity ejecta would explain the nearly identical post-maximum spectra. These two supernovae further highlight the diversity within the SNe Iax class, as well as the challenges in spectroscopically identifying and phasing these objects, especially at early epochs.

Jitter and phase noise of ADPLL due to PSN with deterministic frequency

NASA Astrophysics Data System (ADS)

Deng, Xiaoying; Yang, Jun; Wu, Jianhui

2011-09-01

In this article, jitter and phase noise of all-digital phase-locked loop due to power supply noise (PSN) with deterministic frequency are analysed. It leads to the conclusion that jitter and phase noise heavily depend on the noise frequency. Compared with jitter, phase noise is much less affected by the deterministic PSN. Our method is utilised to study a CMOS ADPLL designed and simulated in SMIC 0.13 µm standard CMOS process. A comparison between the results obtained by our method and those obtained by simulation and measurement proves the accuracy of the predicted model. When the digital controlled oscillator was corrupted by PSN with 100 mVpk-pk, the measured jitters were 33.9 ps at the rate of fG = 192 MHz and 148.5 ps at the rate of fG = 40 MHz. However, the measured phase noise was exactly the same except for two impulses appearing at 192 and 40 MHz, respectively.

Compensated second-order recoupling: application to third spin assisted recoupling†

PubMed Central

Giffard, Mathilde; Hediger, Sabine; Lewandowski, Józef R.; Bardet, Michel; Simorre, Jean-Pierre; Griffin, Robert G.; De Paëpe, Gaël

2015-01-01

We consider the effect of phase shifts in the context of second-order recoupling techniques in solid-state NMR. Notably we highlight conditions leading to significant improvements for the Third Spin Assisted Recoupling (TSAR) mechanism and demonstrate the benefits of resulting techniques for detecting long-distance transfer in biomolecular systems. The modified pulse sequences of PAR and PAIN-CP, Phase-Shifted Proton Assisted Recoupling (AH-PS-PAR) and Phase-Shifted Proton-Assisted Insensitive Nuclei Cross Polarization (ABH-PS-PAIN-CP), still rely on cross terms between heteronuclear dipolar couplings involving assisting protons that mediate zero-quantum polarization transfer between low-γ nuclei (13C–13C, 15N–15N, 15N–13C polarization transfer). Using Average Hamiltonian Theory we show that phase inversion compensates off-resonance contributions and yields improved polarization transfer as well as substantial broadening of the matching conditions. PS-TSAR greatly improves on the standard TSAR based methods because it alleviates their sensitivity to precise RF settings which significantly enhances robustness of the experiments. We demonstrate these new methods on a 19.6 kDa protein (U–[15N, 13C]-YajG) at high magnetic fields (up to 900 MHz 1H frequency) and fast sample spinning (up to 65 kHz MAS frequency). PMID:22513727

Honeycomb Films with Core-Shell Dispersed Phases Prepared by the Combination of Breath Figures and Phase Separation Process of Ternary Blends.

PubMed

Del Campo, A; de León, A S; Rodríguez-Hernández, J; Muñoz-Bonilla, A

2017-03-21

Herein, we propose a strategy to fabricate core-shell microstructures ordered in hexagonal arrays by combining the breath figures approach and phase separation of immiscible ternary blends. This simple strategy to fabricate these structures involves only the solvent casting of a ternary polymer blend under moist atmosphere, which provides a facile and low-cost fabrication method to obtain the porous structures with a core-shell morphology. For this purpose, blends consisting of polystyrene (PS) as a major component and PS 40 -b-P(PEGMA300) 48 amphiphilic copolymer and polydimethylsiloxane (PDMS) as minor components were dissolved in tetrahydrofuran and cast onto glass wafers under humid conditions, 70% of relative humidity. The resulting porous morphologies were characterized by optical and confocal Raman microscopy. In particular, confocal Raman results demonstrated the formation of core-shell morphologies into the ordered pores, in which the PS forms the continuous matrix, whereas the other two phases are located into the cavities (PDMS is the core while the amphiphilic copolymer is the shell). Besides, by controlling the weight ratio of the polymer blends, the structural parameters of the porous structure such as pore diameter and the size of the core can be effectively tuned.

A Quaternary Sodium Superionic Conductor - Na 10.8Sn 1.9PS 11.8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Zhaoxin; Shang, Shun -Li; Gao, Yue

Sulfide-based Na-ion conductors are promising candidates as solid-state electrolytes (SSEs) for fabrication of solid-state Na-ion batteries (NIBs) because of their high ionic conductivities and low grain boundary resistance. Currently, most of the sulfide-based Na-ion conductors with high conductivities are focused on Na 3PS 4 phases and its derivatives. It is desirable to develop Na-ion conductors with new composition and crystal structure to achieve superior ionic conductivities. Here we report a new quaternary Na-ion conductor, Na 10.8Sn 1.9PS 11.8, exhibiting a high ionic conductivity of 0.67 mS cm –1 at 25 °C. This high ionic conductivity originates from the presence ofmore » a large number of intrinsic Na-vacancies and three-dimensional Na-ion conduction pathways, which has been confirmed by single-crystal X-ray diffraction and first-principles calculations. In conclusion, the Na 10.8Sn 1.9PS 11.8 phase is further evaluated as an electrolyte in a Na-Sn alloy/TiS 2 battery, demonstrating its potential application in all-solid-state NIBs.« less

A Quaternary Sodium Superionic Conductor - Na 10.8Sn 1.9PS 11.8

DOE PAGES

Yu, Zhaoxin; Shang, Shun -Li; Gao, Yue; ...

2018-01-31

Sulfide-based Na-ion conductors are promising candidates as solid-state electrolytes (SSEs) for fabrication of solid-state Na-ion batteries (NIBs) because of their high ionic conductivities and low grain boundary resistance. Currently, most of the sulfide-based Na-ion conductors with high conductivities are focused on Na 3PS 4 phases and its derivatives. It is desirable to develop Na-ion conductors with new composition and crystal structure to achieve superior ionic conductivities. Here we report a new quaternary Na-ion conductor, Na 10.8Sn 1.9PS 11.8, exhibiting a high ionic conductivity of 0.67 mS cm –1 at 25 °C. This high ionic conductivity originates from the presence ofmore » a large number of intrinsic Na-vacancies and three-dimensional Na-ion conduction pathways, which has been confirmed by single-crystal X-ray diffraction and first-principles calculations. In conclusion, the Na 10.8Sn 1.9PS 11.8 phase is further evaluated as an electrolyte in a Na-Sn alloy/TiS 2 battery, demonstrating its potential application in all-solid-state NIBs.« less

New approaches on the analyses of thermolabile coffee diterpenes by gas chromatography and its relationship with cup quality.

PubMed

Novaes, Fábio Junior Moreira; Oigman, Silvia Siag; de Souza, Rodrigo Octavio Mendonça Alves; Rezende, Claudia Moraes; de Aquino Neto, Francisco Radler

2015-07-01

A new gas chromatography method using pulsed split injector (PS-GC) was validated to quantify thermolabile diterpenes cafestol, kahweol and isokahweol in methanolysed Arabica coffee oils. Linearity was 0.99 from 8 to 69mgmL(-1), recovery ranged from 99% to 101% and precision of less than 4% was obtained. Besides, Soxhlet extraction time was evaluated and Tukey׳s test indicated that the mass of diterpenes obtained in 4h is equivalent to a 16h period, which represents a space-time yield four times higher. The microwave assisted methanolysis proved to be efficient to quantitatively convert the natural diterpene esters in their respective alcohols and fatty acid methyl esters, accompanied by PS-GC. Also, the intact diterpene esters were analyzed by GC for the first time by the comparison between cold on-column (COC) and PS injection techniques. In all these stages, the molecular integrity of the thermolabile furokaurane diterpenes was maintained. The methanolysed oils from 13 samples of green Brazilian Arabica coffees were analyzed by PS-GC and the diterpenes composition varied from 8 to 12% w/w in oil and 0.7-1% in coffee beans. The ratio between cafestol and kahweol was successfully used to predict the quality of coffee even before the roasting and brewing processes. Copyright © 2015 Elsevier B.V. All rights reserved.

Templated cocrystallization of cholesterol and phytosterols from microemulsions

NASA Astrophysics Data System (ADS)

Rozner, Shoshana; Popov, Inna; Uvarov, Vladimir; Aserin, Abraham; Garti, Nissim

2009-08-01

A major cause of cardiovascular disease is high cholesterol (CH) levels in the blood, a potential solution to which is the intake of phytosterols (PS) known as CH-reducing agents. One mechanism proposed for PS activity is the mutual cocrystallization of CH and PS from dietary mixed micelles (DMM), a process that removes excess CH from the transporting micelles. In this study, microemulsions (MEs) were used both as a model system for cocrystallization mimicking DMM and as a possible alternative pathway, based on the competitive solubilization of CH and PS, to reduce solubilized CH transport levels from the ME. The effects of different CH/PS ratios, aqueous dilution, and lecithin-based MEs on sterol crystallization were studied. The precipitated crystals from the ME-loaded system with PS alone and from that loaded with 1:1 or 1:3 CH/PS mixtures were significantly influenced by ME microstructure and by dilution with aqueous phase (X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC) results). No new polymorphic structures were detected apart from the corresponding sterol hydrates. Mixed crystal morphology and the habit of the precipitated sterols were strongly affected by the CH/PS ratio and the structures of the diluted ME. As the amount of PS in the mixture increased or as the ME aqueous dilution proceeded, precipitated crystal shape became more needle-like. The mixed sterols seemed to be forming eutectic solids.

Effects of aggregation on the excitation dynamics of LH2 from Thermochromatium tepidum in aqueous phase and in chromatophores.

PubMed

Yang, Fan; Yu, Long-Jiang; Wang, Peng; Ai, Xi-Cheng; Wang, Zheng-Yu; Zhang, Jian-Ping

2011-06-23

We carried out femtosecond magic-angle and polarized pump-probe spectroscopies for the light-harvesting complex 2 (LH2) from Thermochromatium (Tch.) tepidum in aqueous phase and in chromatophores. To examine the effects of LH2 aggregation on the dynamics of excitation energy transfer, dominant monodispersed and aggregated LH2s were prepared by controlling the surfactant concentrations. The aqueous preparations solubilized with different concentrations of n-dodecyl-β-D-maltoside (DDM) show similar visible-to-near-infrared absorption spectra, but distinctively different aggregation states, as revealed by using dynamic light scattering. The B800 → B850 intra-LH2 energy transfer time was determined to be 1.3 ps for isolated LH2, which, upon aggregation in aqueous phase or clustering in chromatophores, shortened to 1.1 or 0.9 ps, respectively. The light-harvesting complex 1 (LH1) of this thermophilic purple sulfur bacterium contains bacteriochlorophyll a absorbing at 915 nm (B915), and the LH2(B850) → LH1(B915) intercomplex transfer time in chromatophores was found to be 6.6 ps. For chromatophores, a depolarization time of 21 ps was derived from the anisotropy kinetics of B850*, which is attributed to the migration of B850* excitation before being trapped by LH1. In addition, the B850* annihilation is accelerated upon LH2 aggregation in aqueous phase, but it is much less severe upon LH2 clustering in the intracytoplasmic membrane. These results are helpful in understanding the light-harvesting function of a bacterial photosynthetic membrane incorporating different types of antenna complexes.

Photonic harmonic up-converter based on a self-oscillating optical frequency comb using a DP-DPMZM

NASA Astrophysics Data System (ADS)

Xiao, Xuedi; Li, Shangyuan; Xie, Zhengyang; Peng, Shaowen; Wu, Dexin; Xue, Xiaoxiao; Zheng, Xiaoping; Zhou, Bingkun

2018-04-01

A photonic harmonic up-converter based on a self-oscillating optical frequency comb (OFC) utilizing an integrated dual-polarization dual-parallel Mach-Zehnder Modulator (DP-DPMZM) is proposed and experimentally demonstrated. One DPMZM is used to generate the optoelectronic oscillator (OEO)-based OFC, and the rest one is used to generate the optical-modulated intermediate frequency (IF) signal. Beating these two signals, the up-converted signals at different bands would be obtained. As the OFC is generated based on the OEO loop, phase noise can be very low, ensuring good phase noise properties of the up-converted signals. Moreover, frequency spacing between the combs is dependent on oscillating frequency of the OEO, which can be as large as tens of gigahertz. Thus IF signals with large bandwidth can be up-converted to RF bands without aliasing. Experimentally, the 2.5 GHz IF signal is simultaneously up-converted to 13.3, 24.1, and 34.9 GHz by a self-oscillating 7-line OFC spacing at 10.8 GHz. Owing to good phase noise property of the OEO, the up-converted signals at 13.3 and 24.1 GHz maintain the phase noise of the IF signal from 1 KHz to 100 KHz offset. The results show that the converter is promising for multi-band radar and satellite navigation applications.

Structure of the Los Angeles Basin from Ambient Noise and Receiver Function Analysis

NASA Astrophysics Data System (ADS)

Clayton, R. W.; Ma, Y.; Cochran, E. S.

2015-12-01

We show the results from the LASSIE seismic experiment, which consists of a dense (1-km spacing) linear array of broadband stations deployed across the LA basin for approximately two months. Two common methods - ambient noise and receiver function (RF) - are applied to determine the velocity and structure of the basin. The basin RFs are complicated, however, the dense array enhances the lateral coherence of the signals and allows the structure to be imaged. The basement shape is clearly shown in the migrated image of the PpPs phase. The Ps conversion at the basement is the largest signal (including the direct wave) in the first 3 s. However, the Ps phase does not form as clear an image compared with the PpPs phase, possibly due to a requirement of more accurate velocity model. The surface wave signals from the ambient noise cross-correlations between LASSIE and surrounding SCSN stations are used for velocity inversion. A linear Dix-type inversion (Haney and Tsai, 2015, Geophysics) is applied to the extracted dispersion curves. The 1-10 s period Rayleigh wave and the 1-8 s period Love wave dispersion curves provide excellent constraints on top 5 km SV and top 3 km SH velocity structures respectively. Strong anisotropy (SV > SH) is observed for the top 1 km, and we plan to use this result to infer the fracture orientation and density of the shallow sedimentary rocks.

Phase 2 design study of the electronic assembly for the HRUV spectrometer/polarimeter intended for the solar maximum mission. Implementation phase program plan, revision A

NASA Technical Reports Server (NTRS)

1977-01-01

The primary function of the implementation phase is to convert the ERA design of the design study phase into deliverable flight hardware. The development aspects of the experiment logic unit, the dual power converter, the junction box and the cables are considered.

Status of the development of Brazilian Decimetric Array (BDA)

NASA Astrophysics Data System (ADS)

Sawant, Hanumant; Fernandes, Francisco; Chellasamy, Ebenezer; Cecatto, Jose R.; Costa, D. Joaquim; Sirothia, Sandeep Kumar; Subramanian, Koovapady

BDA will consists of 38 antennas of 4 meters diameter, capable of operating at frequency range of (1.2-1.7, 2.8 and 5.6) GHz. The array will be spread over the distances 2 x 1 km in a T shape with longest base line in E-W direction, having spatial resolution of ~10 sec of arc at 5.6 GHz. The visibility data can be processed to provide two dimensional images at a time resolution of 100 ms (or higher). In the second phase of the BDA, almost all systems of the 26 antennas are installed. LO of 10 MHz is send from receiver room to each receiver located in the each antenna tower. This receiver operates in the frequency range of 1-6 GHz and converts received signal to 70 MHz. Fiber optical system is partially installed in tower converts 70 MHz signal to optical signal and send to receiver room with low loss and phase compensation of 100 ps, where it is converted back to 70 MHz and processed to give output of 0-5 MHz bandpass and further processed by the correlator. Tracking system, with Dual feed back facility has tracking accuracy of +/- 3 arc minutes. All safety features are installed, with on line offset adjustment. Data logging and event logging for future investigations are available. Tracking system was tested for one month with 8 hours tracking and results of these will also be presented. Field programmable Gate Array based complex correlator system capable of producing all four Stokes parameters was designed and developed for correlating base band outputs from 38 antennas. The correlator produces delay and fringe corrected, visibility correlations between any two signal channels of the same polarizations from any given pair of antennas, providing visibility data. Fringes using this system have been obtained for baseline combinations of 12 fully installed antennas. Simulations of the UV coverage and imaging were carried out for the full synthesis observations of sources at different configurations and various declinations in -70 to +23 degrees range. The current system can image the Sun with spatial resolution of 3.40 x 4.54 arc min at 1.4 GHz. Results of the each of the above systems along with the observed fringes from the FPGA based complex correlator system from non redundant 12 antennas in two dimensions will be presented. BDA phase II will be operational shortly.

Theory and Measurement of Partially Correlated Persistent Scatterers

NASA Astrophysics Data System (ADS)

Lien, J.; Zebker, H. A.

2011-12-01

Interferometric synthetic aperture radar (InSAR) time-series methods can effectively estimate temporal surface changes induced by geophysical phenomena. However, such methods are susceptible to decorrelation due to spatial and temporal baselines (radar pass separation), changes in orbital geometries, atmosphere, and noise. These effects limit the number of interferograms that can be used for differential analysis and obscure the deformation signal. InSAR decorrelation effects may be ameliorated by exploiting pixels that exhibit phase stability across the stack of interferograms. These so-called persistent scatterer (PS) pixels are dominated by a single point-like scatterer that remains phase-stable over the spatial and temporal baseline. By identifying a network of PS pixels for use in phase unwrapping, reliable deformation measurements may be obtained even in areas of low correlation, where traditional InSAR techniques fail to produce useful observations. PS identification is challenging in natural terrain, due to low reflectivity and few corner reflectors. Shanker and Zebker [1] proposed a PS pixel selection technique based on maximum-likelihood estimation of the associated signal-to-clutter ratio (SCR). In this study, we further develop the underlying theory for their technique, starting from statistical backscatter characteristics of PS pixels. We derive closed-form expressions for the spatial, rotational, and temporal decorrelation of PS pixels as a function of baseline and signal-to-clutter ratio. We show that previous decorrelation and critical baseline expressions [2] are limiting cases of our result. We then describe a series of radar scattering simulations and show that the simulated decorrelation matches well with our analytic results. Finally, we use our decorrelation expressions with maximum-likelihood SCR estimation to analyze an area of the Hayward Fault Zone in the San Francisco Bay Area. A series of 38 images of the area were obtained from C-band ERS radar satellite passes between May 1995 and December 2000. We show that the interferogram stack exhibits PS decorrelation trends in agreement with our analytic results. References 1. P. Shanker and H. Zebker, "Persistent scatterer selection using maximum likelihood estimation," Geophysical Research Letters, Vol. 34, L22301, 2007. 2. H. Zebker and J. Villasenor, "Decorrelation in Interferometric Radar Echos," IEEE Transactions on Geoscience and Remote Sensing, Vol. 30, No. 5, Sept. 1992.

Simultaneous measurement of temperature and strain using a phase-shifted fiber Bragg grating inscribed by femtosecond laser

NASA Astrophysics Data System (ADS)

Jiang, Yajun; Liu, Chi; Li, Dong; Yang, Dexing; Zhao, Jianlin

2018-04-01

A novel method for simultaneous measurement of temperature and strain using a single phase-shifted fiber Bragg grating (PS-FBG) is proposed. The PS-FBG is produced by exposing the fusion-spliced fiber with a femtosecond laser and uniform phase mask. Due to the non-uniform structure and strain distribution in the fusion-spliced region, the phase-shift changes with different responses during increases to the temperature and strain; by measuring the central wavelengths and the loss difference of two transmission dips, temperature and strain can be determined simultaneously. The resolutions of this particular sensor in measuring temperature and strain are estimated to be  ±1.5 °C and  ±12.2 µɛ in a range from  -50 °C to 150 °C and from 0 µɛ to 2070 µɛ.

Sub-5-ps, multimegawatt peak-power pulses from a fiber-amplified and optically compressed passively Q-switched microchip laser.

PubMed

Steinmetz, A; Jansen, F; Stutzki, F; Lehneis, R; Limpert, J; Tünnermann, A

2012-07-01

We report on high-energy picosecond pulse generation from a passively Q-switched and fiber-amplified microchip laser system. Initially, the utilized microchip lasers produce pulses with durations of around 100 ps at 1064 nm central wavelength. These pulses are amplified to energies exceeding 100 μJ, simultaneously chirped and spectrally broadened by self-phase modulation using a double stage amplifier based on single-mode LMA photonic crystal fibers at repetition rates of up to 1 MHz. Subsequently, the pulse duration of chirped pulses is reduced by means of nonlinear pulse compression to durations of 2.7 ps employing a conventional grating compressor and 4.7 ps using a compact compressor based on a chirped volume Bragg grating.

Synthesis and structure of novel lithium-ion conductor Li7Ge3PS12

NASA Astrophysics Data System (ADS)

Inoue, Yuki; Suzuki, Kota; Matsui, Naoki; Hirayama, Masaaki; Kanno, Ryoji

2017-02-01

The novel lithium-ion conductor Li7Ge3PS12 was synthesized by slow cooling from the ternary Li2S-GeS2-P2S5 system, and was shown to exhibit a cubic argyrodite-type structure. The phase composition was determined by varying the ratio of starting materials; the observed monophasic properties were close to those for the Li7Ge3PS12 composition. The lattice parameter (a =9.80192(3) Å) of Li7Ge3PS12 was slightly smaller than that of Li7PS6 (a =9.993 Å), indicating that substitution of a Li cation by the smaller Ge cation contracted the cubic lattice. In addition, the novel structure consisted of a framework composed of four isolated (Ge/P)S4 tetrahedra. Li+ ions occupied tetrahedral sites within the framework, forming a three-dimensional conduction pathway. Finally, Li7Ge3PS12 exhibited a high ionic conductivity of 1.1×10-4 S cm-1 at 25 °C and an activation energy of 25 kJ mol-1.

Microbubble-Assisted Ultrasound-Induced Transient Phosphatidylserine Translocation.

PubMed

Escoffre, Jean-Michel; Derieppe, Marc; Lammertink, Bart; Bos, Clemens; Moonen, Chrit

2017-04-01

Microbubble-assisted ultrasound (sonopermeabilization) results in reversible permeabilization of the plasma membrane of cells. This method is increasingly used in vivo because of its potential to deliver therapeutic molecules with limited cell damage. Nevertheless, the effects of sonopermeabilization on the plasma membrane remain not fully understood. We investigated the influence of sonopermeabilization on the transverse mobility of phospholipids, especially on phosphatidylserine (PS) externalization. We performed studies using optical imaging with Annexin V and FM1-43 probes to monitor PS externalization of rat glioma C6 cells. Sonopermeabilization induced transient membrane permeabilization, which is positively correlated with reversible PS externalization. This membrane disorganization was temporary and not associated with loss of cell viability. Sonopermeabilization did not induce PS externalization via activation of the scramblase. We hypothesize that acoustically induced membrane pores may provide a new pathway for PS migration between both membrane leaflets. During the membrane-resealing phase, PS asymmetry may be re-established by amino-phospholipid flippase activity and/or endocytosis, along with exocytosis processes. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Preparation and characterization of a thermoresponsive gigaporous medium for high-speed protein chromatography.

PubMed

Qu, Jian-Bo; Chen, Yan-Li; Huan, Guan-Sheng; Zhou, Wei-Qing; Liu, Jian-Guo; Zhu, Hu; Zhang, Xiao-Yun

2015-01-01

A high-speed thermoresponsive medium was developed by grafting poly(N-isopropylacrylamide-co-butyl methacrylate) (P(NIPAM-co-BMA)) brushes onto gigaporous polystyrene (PS) microspheres via surface-initiated atom transfer radical polymerization (ATRP) technique, which has strong mechanical strength, good chemical stability and high mass transfer rate for biomacromolecules. The gigaporous structure, surface chemical composition, static protein adsorption, and thermoresponsive chromatographic properties of prepared medium (PS-P(NIPAM-co-BMA)) were characterized in detail. Results showed that the PS microspheres were successfully grafted with P(NIPAM-co-BMA) brushes and that the gigaporous structure was robustly maintained. After grafting, the nonspecific adsorption of proteins on PS microspheres was greatly reduced. A column packed with PS-P(NIPAM-co-BMA) exhibited low backpressure and significant thermo-responsibility. By simply changing the column temperature, it was able to separate three model proteins at the mobile phase velocity up to 2167 cm h(-1). In conclusion, the thermoresponsive polymer brushes grafted gigaporous PS microspheres prepared by ATRP are very promising in 'green' high-speed preparative protein chromatography. Copyright © 2014 Elsevier B.V. All rights reserved.

Diagnosing Organizational Innovation: Measuring the Capacity for Innovation

ERIC Educational Resources Information Center

Cropley, David H.; Cropley, Arthur J.; Chiera, Belinda A.; Kaufman, James C.

2013-01-01

Organizational innovation involves reconciling many contradictions or paradoxes. Dividing the process of innovation into phases ranging from Activation to Validation and examining each phase in terms of the six Ps of creativity offers a framework for making sense of these contradictions. The Innovation Phase Assessment Instrument (IPAI) was…

Ultrafast Physics Behind the Nonradiative Relaxation Process of Chromium Ions in Forsterite Crystals.

NASA Astrophysics Data System (ADS)

Demos, Stavros Gregorios

The nonradiative relaxation following photoexcitation has been studied in Cr^{4+} -doped forsterite (Mg_2SiO _4) using picosecond laser excitation and ultrasensitive photon counting detection. The experimental techniques utilized were time resolved antiStokes Raman scattering and up-converted hot and ordinary luminescence. The up-converted hot luminescence technique allowed the investigation of the upper state nonradiative relaxation of the excited state manifold of Cr^{4+ }-doped forsterite. The excitation involves the absorption of two photons per photoexcited ion in a two-step absorption. Discrete peaks are observed in the hot up-converted luminescence spectrum and are attributed to the population of nonequilibrium vibronic levels during the deexcitation of the ions by phonon emission. This work reveals that the phonon modes participating in the initial steps of the nonradiative relaxation of the photoexcited ions have energies 218 +/- 20, 325 +/- 20, 365 +/- 20 and 513 +/- 12 cm^ {-1}. The shape of the luminescence spectral envelope suggests two electronic bottlenecks at ~2.1 and ~2.45 eV associated with slower rates of vibrational relaxation at different parts of the excited state manifold. Time resolved measurements indicated that the average time for phonon emission is of the order of hundreds of fs. Information on the nonequilibrium phonon dynamics of the 225, 335 and 370 cm^{-1} modes of forsterite has been obtained using time resolved Raman scattering. Laser pulses of 450 fs in duration and 590 nm in wavelength were used to excite the Cr ions 2.1 eV above the ground state. The probe pulses (obtained from the same laser) are monitoring the nonequilibrium phonon population through the intensity of the antiStokes Raman lines at various pump-probe delay times. Experiments were performed at room and liquid nitrogen temperatures. The observed nonequilibrium phonon populations are associated with the overall complex nonradiative decay following the excitation of the impurity Cr^{4+} ions. Using rate equations to describe the electron -lattice system, the nonradiative relaxation time and the phonon lifetimes were estimated by fitting to the experimental data. The nonradiative relaxation time is estimated to be in the order of few ps while the phonon lifetimes are of the order of 10 ps. Best fit suggests the presence of an electronic bottleneck immediately after photoexcitation with an estimated lifetime of 3 ps at room temperature.

Feasibility of spectral-domain phase-sensitive optical coherence tomography for middle ear vibrometry

PubMed Central

Nguyen-Huynh, Anh; Wang, Ruikang K.; Jacques, Steven L.; Choudhury, Niloy; Nuttall, Alfred L.

2012-01-01

Abstract. We describe a novel application of spectral-domain phase-sensitive optical coherence tomography (SD PS-OCT) to detect the tiny motions of the middle ear structures, such as the tympanic membrane and ossicular chain, and their morphological features for differential diagnosis of CHL. This technique has the potential to provide meaningful vibration of ossicles with a vibration sensitivity of ∼0.5  nm at 1 kHz of acoustic stimulation. To the best of our knowledge, this is the first demonstration of depth-resolved vibration imaging of ossicles with a PS-OCT system at a nanometer scale. PMID:22734728

Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering for gas-phase temperature measurements

NASA Astrophysics Data System (ADS)

Miller, Joseph Daniel

Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) is employed for quantitative gas-phase temperature measurements in combustion processes and heated flows. In this approach, ultrafast 100-fs laser pulses are used to induce vibrational and rotational transitions in N2 and O2, while a third spectrally narrowed picosecond pulse is used to probe the molecular response. Temporal suppression of the nonresonant contribution and elimination of collisional effects are achieved by delay of the probe pulse, while sufficient spectral resolution is maintained for frequency-domain detection and thermometry. A theoretical framework is developed to model experimental spectra by phenomenologically describing the temporal evolution of the vibrational and rotational wavepackets as a function of temperature and pressure. Interference-free, single-shot vibrational fs/ps CARS thermometry is demonstrated at 1-kHz from 1400-2400 K in a H2-air flame, with accuracy better than 3%. A time-asymmetric exponential pulse shape is introduced to optimize nonresonant suppression with a 103 reduction at a probe delay of 0.31 ps. Low-temperature single-shot thermometry (300-700 K) with better than 1.5% accuracy is demonstrated using a fully degenerate rotational fs/ps CARS scheme, and the influence of collision energy transfer on thermometry error is quantified at atmospheric pressure. Interference-free thermometry, without nonresonant contributions and collision-induced error, is demonstrated for the first time using rotational fs/ps CARS at room temperature and pressures from 1-15 atm. Finally, the temporal and spectral resolution of fs/ps CARS is exploited for transition-resolved time-domain measurements of N2 and O2 self-broadened S-branch Raman linewidths at pressures of 1-20 atm.

Onset of ice VII phase during ps laser pulse propagation through liquid water

NASA Astrophysics Data System (ADS)

Paturi, Prem Kiran; Vaddapally, Rakesh Kumar; Acrhem Team

2015-06-01

Water dominantly present in liquid state on earth gets transformed to crystalline polymorphs under different dynamic loading conditions. Out of 15 different crystalline phases discovered till date, ice VII is observed to be stable over wide pressure (2-63 GPa) and temperature (>273 K) ranges. We present the onset of ice VII phase at low threshold of 2 mJ/pulse during 30 ps (532 nm, 10 Hz) laser pulse induced shock propagating through liquid water. Role of input pulse energy on the evolution of Stoke's and anti-Stoke's Raman shift of the dominant A1g mode of ice VII, filamentation, free-electrons, plasma shielding is presented. The H-bond network rearrangement, electron ion energy transfer time coinciding with the excitation pulse duration supported by the filamentation and plasma shielding of the ps laser pulses reduced the threshold of ice VII structure formation. Filamentation and the plasma shielding have shown the localized creation and sustenance of ice VII structure in liquid water over 3 mm length and 50 μm area of cross-section. The work is supported by Defence Research and Developement Organization, India through Grants-in-Aid Program.

SU-E-T-410: Fringe Stability and Phase Shift Measurements in a Michelson Interferometer for Optical Calorimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flores-Martinez, E; Malin, M; DeWerd, L

2014-06-01

Purpose: To identify the variables limiting the resolution of a Michelson interferometer used to measure phase shifts (PS) in water as part of a radiometric calorimeter. Methods: We investigated the output stability of a He-Ne laser and a laser diode. The short and long term stability of the fringe pattern in a Michelson interferometer was tested with different types of lasers, thermal insulation arrangements, damping systems and optical mounts to optimize system performance. PS were induced by electrically heating water in a 1 cm quartz cuvette located in one of the interferometer arms. The PS was calculated from fringe intensitymore » changes and compared to a calculated PS using thermocouple-measured temperature changes in the water. Results: The intensity of the laser diode is more stable, but the gas laser’s profile is more suitable for fringe analysis and has better temporal coherence. The laser requires a warm-up time of 4 hours before its output is stabilized (SNR>95). The fringe’s stability strongly depends on the thermal insulation. When the interferometer is exposed to ambient temperature swings of 0.7 K, it is not possible to stabilize the fringe pattern. Enclosing the system in a 2.5 cm-thick Styrofoam box improves the SNR, but further insulation will be needed to increase the SNR above 50. High frequency noise is significantly reduced by damping the system.Inducing a temperature rise in water, starting at 299 K, the average temperature increase for a 2π PS is 0.29 ± 0.02 K and the proportionality constant is -21.1 ± 0.8 radians/K. This is 5.8% lower than the calculated value using the thermocouple. Conclusion: Interferometric PS measurements of temperature may provide an alternative to thermistors for water calorimetry. The resolution of the current prototype is limited by ambient temperature stability. Calculated and measured thermally-induced PS in water agreed to within 5.8%.« less

DETERMINATE and LATE FLOWERING are two TERMINAL FLOWER1/CENTRORADIALIS homologs that control two distinct phases of flowering initiation and development in pea.

PubMed

Foucher, Fabrice; Morin, Julie; Courtiade, Juliette; Cadioux, Sandrine; Ellis, Noel; Banfield, Mark J; Rameau, Catherine

2003-11-01

Genes in the TERMINAL FLOWER1 (TFL1)/CENTRORADIALIS family are important key regulatory genes involved in the control of flowering time and floral architecture in several different plant species. To understand the functions of TFL1 homologs in pea, we isolated three TFL1 homologs, which we have designated PsTFL1a, PsTFL1b, and PsTFL1c. By genetic mapping and sequencing of mutant alleles, we demonstrate that PsTFL1a corresponds to the DETERMINATE (DET) gene and PsTFL1c corresponds to the LATE FLOWERING (LF) gene. DET acts to maintain the indeterminacy of the apical meristem during flowering, and consistent with this role, DET expression is limited to the shoot apex after floral initiation. LF delays the induction of flowering by lengthening the vegetative phase, and allelic variation at the LF locus is an important component of natural variation for flowering time in pea. The most severe class of alleles flowers early and carries either a deletion of the entire PsTFL1c gene or an amino acid substitution. Other natural and induced alleles for LF, with an intermediate flowering time phenotype, present no changes in the PsTFL1c amino acid sequence but affect LF transcript level in the shoot apex: low LF transcript levels are correlated with early flowering, and high LF transcript levels are correlated with late flowering. Thus, different TFL1 homologs control two distinct aspects of plant development in pea, whereas a single gene, TFL1, performs both functions in Arabidopsis. These results show that different species have evolved different strategies to control key developmental transitions and also that the genetic basis for natural variation in flowering time may differ among plant species.

Investigation of homodyne demodulation of RZ-BPSK signal based on an optical Costas loop

NASA Astrophysics Data System (ADS)

Zhou, Haijun; Zhu, Zunzhen; Xie, Weilin; Dong, Yi

2018-01-01

We demonstrate the coherent detection of 10 Gb/s return-to-zero (RZ) binary phase-shift keying (BPSK) signal based on a homodyne Costas optical phase-locked loop (OPLL). It demonstrates time misalignment tolerance of +/- 10% of the transmitted RZ-BPSK signal, i.e. -20 to +20 ps between the pulse carver and the phase modulator for 5 Gb/s RZ-BPSK signal, -10 to +10 ps or 10 Gb/s RZ-BPSK signal. Besides, the Costas coherent receiver shows a 2.5 dB sensitivity improvement over conventional 5 Gb/s NRZ-BPSK and a 1.4 dB over 10 Gb/s NRZ-BPSK only at the cost of slightly higher residual phase error. Those merits of sufficient tolerance to misalignment, higher receiver sensitivity, and low residual phase error of RZ-BPSK modulation are beneficial to be applied in free space optical (FSO) communication to achieve higher link budget, longer transmission distance.

Towards ultraporous poly(L-lactide) scaffolds from quaternary immiscible polymer blends.

PubMed

Virgilio, N; Sarazin, P; Favis, B D

2010-08-01

Ultraporous poly(l-lactide) (PLLA) scaffolds were prepared by melt-processing quaternary ethylene propylene diene rubber/poly(epsilon-caprolactone)/polystyrene/poly(l-lactide) (EPDM/PCL/PS/PLLA) 45/45/5/5 %vol. polymer blends modified with a PS-b-PLLA diblock copolymer. The morphology consists of a PS+PLLA+copolymer sub-blend layer forming at the interface of the EPDM and PCL phases. Quiescent annealing and interfacial modification using the block copolymer are used to control the blend microstructure. The ultraporous structure is subsequently obtained by selectively extracting the EPDM, PS and PCL phases. The PLLA scaffolds modified with the PS-b-PLLA copolymer present themselves as fully interconnected porous networks with asymmetric channel walls, one side being smooth while the other is covered with an array of submicron-sized PLLA droplets. They are prepared with a high degree of control over the pore size, with averages ranging from 5microm to over 100microm and a specific surface from 9.1 to 23.1m(2)/g of PLLA, as annealing is carried out from 0 to 60min. The void volume reaches values as high as 95% and in all cases the shape and dimensions of the scaffolds are maintained with a high level of integrity. The proposed method represents a comprehensive approach towards the design and generation of porous PLLA scaffolds based on complex morphologies from melt-processed multiphase polymer systems. Copyright 2010 Elsevier Ltd. All rights reserved.

Polymerization of styrene with cyclopentadienyl nickel complex/methylaluminoxane

NASA Astrophysics Data System (ADS)

Yu, Dongping; Zhang, Danfeng

2017-09-01

Polystyrene was synthesized by Cp(CH2CH2OCH3)NiCl(PPh3) in the presence of methylaluminoxane (MAO). This complex displayed a very high activity for styrene polymerization up to 107 g.mol-1Nih-1. 76.6% styrene was converted to polystyrene (PS) with an average molecular (Mn) of 1.13×105 at 50 °C in 30 min. The structure of the obtained polymer was characterized by 1H NMR and FT-IR.

Two-terminal charge tunneling: Disentangling Majorana zero modes from partially separated Andreev bound states in semiconductor-superconductor heterostructures

NASA Astrophysics Data System (ADS)

Moore, Christopher; Stanescu, Tudor D.; Tewari, Sumanta

2018-04-01

We show that a pair of overlapping Majorana bound states (MBSs) forming a partially separated Andreev bound state (ps-ABS) represents a generic low-energy feature in spin-orbit-coupled semiconductor-superconductor (SM-SC) hybrid nanowire in the presence of a Zeeman field. The ps-ABS interpolates continuously between the "garden variety" ABS, which consists of two MBSs sitting on top of each other, and the topologically protected Majorana zero modes (MZMs), which are separated by a distance given by the length of the wire. The really problematic ps-ABSs consist of component MBSs separated by a distance of the order of the characteristic Majorana decay length ξ , and have nearly zero energy in a significant range of control parameters, such as the Zeeman field and chemical potential, within the topologically trivial phase. Despite being topologically trivial, such ps-ABSs can generate signatures identical to MZMs in local charge tunneling experiments. In particular, the height of the zero-bias conductance peak (ZBCP) generated by ps-ABSs has the quantized value 2 e2/h , and it can remain unchanged in an extended range of experimental parameters, such as Zeeman field and the tunnel barrier height. We illustrate the formation of such low-energy robust ps-ABSs in two experimentally relevant situations: a hybrid SM-SC system consisting of a proximitized nanowire coupled to a quantum dot and the SM-SC system in the presence of a spatially varying inhomogeneous potential. We then show that, unlike local measurements, a two-terminal experiment involving charge tunneling at both ends of the wire is capable of distinguishing between the generic ps-ABSs and the non-Abelian MZMs. While the MZMs localized at the opposite ends of the wire generate correlated differential conduction spectra, including correlations in energy splittings and critical Zeeman fields associated with the emergence of the ZBCPs, such correlations are absent if the ZBCPs are due to ps-ABSs emerging in the topologically trivial phase. Measuring such correlations is the clearest and most straightforward test of topological MZMs in SM-SC heterostructures that can be done in a currently accessible experimental setup.

Ultra-fast analog-to-digital converter based on a nonlinear triplexer and an optical coder with a photonic crystal structure.

PubMed

Mehdizadeh, Farhad; Soroosh, Mohammad; Alipour-Banaei, Hamed; Farshidi, Ebrahim

2017-03-01

In this paper, we propose what we believe is a novel all-optical analog-to-digital converter (ADC) based on photonic crystals. The proposed structure is composed of a nonlinear triplexer and an optical coder. The nonlinear triplexer is for creating discrete levels in the continuous optical input signal, and the optical coder is for generating a 2-bit standard binary code out of the discrete levels coming from the nonlinear triplexer. Controlling the resonant mode of the resonant rings through optical intensity is the main objective and working mechanism of the proposed structure. The maximum delay time obtained for the proposed structure was about 5 ps and the total footprint is about 1520  μm².

Note: All-digital CMOS MOS-capacitor-based pulse-shrinking mechanism suitable for time-to-digital converters

NASA Astrophysics Data System (ADS)

Chen, Chun-Chi; Hwang, Chorng-Sii; Lin, You-Ting; Liu, Keng-Chih

2015-12-01

This paper presents an all-digital CMOS pulse-shrinking mechanism suitable for time-to-digital converters (TDCs). A simple MOS capacitor is used as a pulse-shrinking cell to perform time attenuation for time resolving. Compared with a previous pulse-shrinking mechanism, the proposed mechanism provides an appreciably improved temporal resolution with high linearity. Furthermore, the use of a binary-weighted pulse-shrinking unit with scaled MOS capacitors is proposed for achieving a programmable resolution. A TDC involving the proposed mechanism was fabricated using a TSMC (Taiwan Semiconductor Manufacturing Company) 0.18-μm CMOS process, and it has a small area of nearly 0.02 mm2 and an integral nonlinearity error of ±0.8 LSB for a resolution of 24 ps.

Memory deficiency, cerebral amyloid angiopathy, and amyloid-β plaques in APP+PS1 double transgenic rat model of Alzheimer's disease.

PubMed

Klakotskaia, Diana; Agca, Cansu; Richardson, Rachel A; Stopa, Edward G; Schachtman, Todd R; Agca, Yuksel

2018-01-01

Transgenic rat models of Alzheimer's disease were used to examine differences in memory and brain histology. Double transgenic female rats (APP+PS1) over-expressing human amyloid precursor protein (APP) and presenilin 1 (PS1) and single transgenic rats (APP21) over-expressing human APP were compared with wild type Fischer rats (WT). The Barnes maze assessed learning and memory and showed that both APP21 and APP+PS1 rats made significantly more errors than the WT rats during the acquisition phase, signifying slower learning. Additionally, the APP+PS1 rats made significantly more errors following a retention interval, indicating impaired memory compared to both the APP21 and WT rats. Immunohistochemistry using an antibody against amyloid-β (Aβ) showed extensive and mostly diffuse Aβ plaques in the hippocampus and dense plaques that contained tau in the cortex of the brains of the APP+PS1 rats. Furthermore, the APP+PS1 rats also showed vascular changes, including cerebral amyloid angiopathy with extensive Aβ deposits in cortical and leptomeningeal blood vessel walls and venous collagenosis. In addition to the Aβ accumulation observed in arterial, venous, and capillary walls, APP+PS1 rats also displayed enlarged blood vessels and perivascular space. Overall, the brain histopathology and behavioral assessment showed that the APP+PS1 rats demonstrated behavioral characteristics and vascular changes similar to those commonly observed in patients with Alzheimer's disease.

Frequency-doubled green picosecond laser based on K3B6O10Br nonlinear optical crystal

NASA Astrophysics Data System (ADS)

Meng, Luping; Zhang, Ling; Hou, Zhanyu; Wang, Lirong; Xu, Hui; Shi, Meng; Wang, Lingwu; Yang, Yingying; Qi, Yaoyao; He, Chaojian; Yu, Haijuan; Lin, Xuechun; Su, Fufang; Xia, Mingjun; Li, Rukang

2018-05-01

We report a frequency-doubled green picosecond (ps) laser based on K3B6O10Br (KBB) nonlinear optical crystal with cutting angle of θ = 34.7° and φ = 30°. Through intracavity frequency doubling using a type I phase-matched KBB crystal with dimensions of 4 mm × 4 mm × 13.2 mm, the average output power of 185.00 mW green ps laser was obtained with a repetition rate of 80 MHz and pulse width of 25.0 ps. In addition, we present external frequency doubling using KBB crystal. The average output power of 3.00 W green ps laser was generated with a repetition rate of 10 kHz and pulse width of 38.1 ps, which corresponds to a pulse energy of 0.30 mJ and a peak power 7.89 MW, respectively. The experimental results show that KBB crystal is a promising nonlinear optical material.

Evaluation of diatomea algae Thalassiosira weissflogii sensitivity to chloride mercury and methylmercury by chlorophyll fluorescence analysis

NASA Astrophysics Data System (ADS)

Graevskaya, E. E.; Antal, T. K.; Matorin, D. N.; Voronova, E. N.; Pogosyan, S. I.; Rubin, A. B.

2003-05-01

Measurement of chlorophyll fluorescence has been shown to be a rapid, non-invasive, and reliable method to assess photosynthetic performance in a changing environment. In our study, the pulseamplitude-modulation (PAM) - fluorometric method was used to evaluate the sensitivity to chloride mercury and methylmercury chloride of diatomea microalgae Thalassiosira weissflogii. We found that 10^{-6} and 10^{-7} M MeHg led to a slow decrease in the PS II activity following for prolonged lag phase, whereas the algae was not sensitive to the same concentrations of HgCl2. However observed PS II inactivation by methylmercury was not complete and about 10 percents ofthe cells kept the high level of PS II activity as it was shown by microfluorometric analysis. These cells could determine adaptation of algae to methylmercury effect. Both toxicants decreased the rate of PS II reparation, as well as increased a heat pathway of excitation dissipation in PS II antennae complex.

Excitation of photosystem I by 760 nm femtosecond laser pulses: transient absorption spectra and intermediates

NASA Astrophysics Data System (ADS)

Cherepanov, Dmitry A.; Shelaev, Ivan V.; Gostev, Fedor E.; Mamedov, Mahir D.; Petrova, Anastasia A.; Aybush, Arseniy V.; Shuvalov, Vladimir A.; Semenov, Alexey Yu; Nadtochenko, Victor A.

2017-09-01

Excitation of photosystem I (PS I) by a femtosecond 760 nm pump leads to one- and two-photon absorption. The one-photon excitation produces intermediates with transient absorption spectra similar to the spectra of the primary [{{{P}}700}+{{{A}}0}-{{A}}1] and secondary [{{{P}}700}+{{A}}0{{{A}}1}-] ion-radical pairs in the PS I reaction center. The two-photon absorption generates the upper level excited states of chlorophyll (Chl) and carotenoid molecules in the antenna. These excited states are converted into the long-lived intermediates and can be tentatively attributed to the excited and charge-transfer ion-radical states of Chl molecules and to the excited states of carotenoids in the antenna. The transient spectra of intermediates generated by two-photon excitation differ from the transient one-photon spectra of the primary and secondary ion-radical pairs.

The production of molecular positronium

NASA Astrophysics Data System (ADS)

Cassidy, D. B.; Mills, A. P.

2007-09-01

It has been known for many years that an electron and its antiparticle, the positron, may together form a metastable hydrogen-like atom, known as positronium or Ps (ref. 1). In 1946, Wheeler speculated that two Ps atoms may combine to form the di-positronium molecule (Ps2), with a binding energy of 0.4eV. More recently, this molecule has been studied theoretically; however, because Ps has a short lifetime and it is difficult to obtain low-energy positrons in large numbers, Ps2 has not previously been observed unambiguously. Here we show that when intense positron bursts are implanted into a thin film of porous silica, Ps2 is created on the internal pore surfaces. We found that molecule formation occurs much more efficiently than the competing process of spin exchange quenching, which appears to be suppressed in the confined pore geometry. This result experimentally confirms the existence of the Ps2 molecule and paves the way for further multi-positronium work. Using similar techniques, but with a more intense positron source, we expect to increase the Ps density to the point where many thousands of atoms interact and can undergo a phase transition to form a Bose-Einstein condensate. As a purely leptonic, macroscopic quantum matter-antimatter system this would be of interest in its own right, but it would also represent a milestone on the path to produce an annihilation gamma-ray laser.

The production of molecular positronium.

PubMed

Cassidy, D B; Mills, A P

2007-09-13

It has been known for many years that an electron and its antiparticle, the positron, may together form a metastable hydrogen-like atom, known as positronium or Ps (ref. 1). In 1946, Wheeler speculated that two Ps atoms may combine to form the di-positronium molecule (Ps2), with a binding energy of 0.4 eV. More recently, this molecule has been studied theoretically; however, because Ps has a short lifetime and it is difficult to obtain low-energy positrons in large numbers, Ps2 has not previously been observed unambiguously. Here we show that when intense positron bursts are implanted into a thin film of porous silica, Ps2 is created on the internal pore surfaces. We found that molecule formation occurs much more efficiently than the competing process of spin exchange quenching, which appears to be suppressed in the confined pore geometry. This result experimentally confirms the existence of the Ps2 molecule and paves the way for further multi-positronium work. Using similar techniques, but with a more intense positron source, we expect to increase the Ps density to the point where many thousands of atoms interact and can undergo a phase transition to form a Bose-Einstein condensate. As a purely leptonic, macroscopic quantum matter-antimatter system this would be of interest in its own right, but it would also represent a milestone on the path to produce an annihilation gamma-ray laser.

Quality-of-life and performance status results from the phase III RAINBOW study of ramucirumab plus paclitaxel versus placebo plus paclitaxel in patients with previously treated gastric or gastroesophageal junction adenocarcinoma†

PubMed Central

Al-Batran, S.-E.; Van Cutsem, E.; Oh, S. C.; Bodoky, G.; Shimada, Y.; Hironaka, S.; Sugimoto, N.; Lipatov, O. N.; Kim, T.-Y.; Cunningham, D.; Rougier, P.; Muro, K.; Liepa, A. M.; Chandrawansa, K.; Emig, M.; Ohtsu, A.; Wilke, H.

2016-01-01

Background The phase III RAINBOW trial demonstrated that the addition of ramucirumab to paclitaxel improved overall survival, progression-free survival, and tumor response rate in fluoropyrimidine–platinum previously treated patients with advanced gastric/gastroesophageal junction (GEJ) adenocarcinoma. Here, we present results from quality-of-life (QoL) and performance status (PS) analyses. Patients and methods Patients with Eastern Cooperative Oncology Group PS of 0/1 were randomized to receive ramucirumab (8 mg/kg i.v.) or placebo on days 1 and 15 of a 4-week cycle, with both arms receiving paclitaxel (80 mg/m2) on days 1, 8, and 15. Patient-reported outcomes were assessed with the QoL/health status questionnaires EORTC QLQ-C30 and EQ-5D at baseline and 6-week intervals. PS was assessed at baseline and day 1 of every cycle. Time to deterioration (TtD) in each QLQ-C30 scale was defined as randomization to first worsening of ≥10 points (on 100-point scale) and TtD in PS was defined as first worsening to ≥2. Hazard ratios (HRs) for treatment effect were estimated using stratified Cox proportional hazards models. Results Of the 665 patients randomized, 650 (98%) provided baseline QLQ-C30 and EQ-5D data, and 560 (84%) also provided data from ≥1 postbaseline time point. Baseline scores for both instruments were similar between arms. Of the 15 QLQ-C30 scales, 14 had HR < 1, indicating similar or longer TtD in QoL for ramucirumab + paclitaxel. Treatment with ramucirumab + paclitaxel was also associated with a delay in TtD in PS to ≥2 (HR = 0.798, P = 0.0941). Alternate definitions of PS deterioration yielded similar results: PS ≥ 3 (HR = 0.656, P = 0.0508), deterioration by ≥1 PS level (HR = 0.802, P = 0.0444), and deterioration by ≥2 PS levels (HR = 0.608, P = 0.0063). EQ-5D scores were comparable between treatment arms, stable during treatment, and worsened at discontinuation. Conclusion In patients with previously treated advanced gastric/GEJ adenocarcinoma, addition of ramucirumab to paclitaxel prolonged overall survival while maintaining patient QoL with delayed symptom worsening and functional status deterioration. ClinicalTrials.gov NCT01170663. PMID:26747859

Ethics and the 7 `P`s` of computer use policies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, T.J.; Voss, R.B.

1994-12-31

A Computer Use Policy (CUP) defines who can use the computer facilities for what. The CUP is the institution`s official position on the ethical use of computer facilities. The authors believe that writing a CUP provides an ideal platform to develop a group ethic for computer users. In prior research, the authors have developed a seven phase model for writing CUPs, entitled the 7 P`s of Computer Use Policies. The purpose of this paper is to present the model and discuss how the 7 P`s can be used to identify and communicate a group ethic for the institution`s computer users.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manaa, M. Riad; Fried, Laurence E.; Kuo, I-Feng W.

We report gas-phase enthalpies of formation for the set of energetic molecules NTO, DADE, LLM-105, TNT, RDX, TATB, HMX, and PETN using the G2, G3, G4, and ccCA-PS3 quantum composite methods. Calculations for HMX and PETN hitherto represent the largest molecules attempted with these methods. G3 and G4 calculations are typically close to one another, with a larger difference found between these methods and ccCA-PS3. Furthermore there is significant uncertainty in experimental values, the mean absolute deviation between the average experimental value and calculations are 12, 6, 7, and 3 kcal/mol for G2, G3, G4, and ccCA-PS3, respectively.

Superior piezoelectric composite films: taking advantage of carbon nanomaterials.

PubMed

Saber, Nasser; Araby, Sherif; Meng, Qingshi; Hsu, Hung-Yao; Yan, Cheng; Azari, Sara; Lee, Sang-Heon; Xu, Yanan; Ma, Jun; Yu, Sirong

2014-01-31

Piezoelectric composites comprising an active phase of ferroelectric ceramic and a polymer matrix have recently found numerous sensory applications. However, it remains a major challenge to further improve their electromechanical response for advanced applications such as precision control and monitoring systems. We here investigated the incorporation of graphene platelets (GnPs) and multi-walled carbon nanotubes (MWNTs), each with various weight fractions, into PZT (lead zirconate titanate)/epoxy composites to produce three-phase nanocomposites. The nanocomposite films show markedly improved piezoelectric coefficients and electromechanical responses (50%) besides an enhancement of ~200% in stiffness. The carbon nanomaterials strengthened the impact of electric field on the PZT particles by appropriately raising the electrical conductivity of the epoxy. GnPs have been proved to be far more promising in improving the poling behavior and dynamic response than MWNTs. The superior dynamic sensitivity of GnP-reinforced composite may be caused by the GnPs' high load transfer efficiency arising from their two-dimensional geometry and good compatibility with the matrix. The reduced acoustic impedance mismatch resulting from the improved thermal conductance may also contribute to the higher sensitivity of GnP-reinforced composite. This research pointed out the potential of employing GnPs to develop highly sensitive piezoelectric composites for sensing applications.

Bioinspired polydopamine sheathed nanofibers for high-efficient in vivo solid-phase microextraction of pharmaceuticals in fish muscle.

PubMed

Xu, Jianqiao; Huang, Shuyao; Wu, Rongben; Jiang, Ruifen; Zhu, Fang; Wang, Jing; Ouyang, Gangfeng

2015-03-17

In this study, electrospun nanofibers were used as solid-phase microextraction (SPME) fiber coatings after substituting the water-soluble sheath of the emulsion electrospun polystyrene (PS)@Plurinic F-127 core-sheath nanofibers with biocompatible and water-stable polydopamine (PDA) and subsequently being appropriately cross-linked with glutaraldehyde (GA) to enhance the strength of the electrospun architecture. The novel custom-made PS@PDA-GA coating was wettable in aqueous solutions and thus exhibited much higher extraction efficiency than the nonsheathed PS nanofiber coating and the thicker polydimethylsiloxane (PDMS) coating. The novel coating also possessed excellent stability (relative standard deviations (RSDs) less than 7.3% for six sampling-desorption cycles), interfiber reproducibility (RSDs less than 14.3%), and antibiofouling ability, which were beneficial for in vivo sampling. The PS@PDA-GA fiber was used to monitor pharmaceuticals in dorsal-epaxial muscle of living fish, and satisfactory sensitivities with the limits of detection in the range of 1.1 (mefenamic acid) to 8.9 (fluoxetine) ng·g(-1) and comparable accuracies to liquid extraction were achieved. In general, this study explored a convenient and effective method to sheath nanofibers for high-efficient in vivo SPME of analytes of interest in semisolid tissues.

Resolution and identification of the protein components of the photosystem II antenna system of higher plants by reversed-phase liquid chromatography with electrospray-mass spectrometric detection.

PubMed

Corradini, D; Huber, C G; Timperio, A M; Zolla, L

2000-07-21

Reversed-phase liquid chromatography (RPLC) was interfaced to mass spectrometry (MS) with an electrospray ion (ESI) source for the separation and accurate molecular mass determination of the individual intrinsic membrane proteins that comprise the photosystem II (PS II) major light-harvesting complex (LHC II) and minor (CP24, CP26 and CP29) antenna system, whose molecular masses range between 22,000 and 29,000. PS II is a supramolecular complex intrinsic of the thylacoid membrane, which plays the important role in photosynthesis of capturing solar energy, and transferring it to photochemical reaction centers where energy conversion occurs. The protein components of the PS II major and minor antenna systems were extracted from spinach thylacoid membranes and separated using a butyl-silica column eluted by an acetonitrile gradient in 0.05% (v/v) aqueous trifluoroacetic acid. On-line electrospray MS allowed accurate molecular mass determination and identification of the protein components of PS II major and minor antenna system. The proposed RPLC-ESI-MS method holds several advantages over sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the conventional technique for studying membrane proteins, including a better protein separation, mass accuracy, speed and efficiency.

Field-quadrature and photon-number correlations produced by parametric processes.

PubMed

McKinstrie, C J; Karlsson, M; Tong, Z

2010-09-13

In a previous paper [Opt. Express 13, 4986 (2005)], formulas were derived for the field-quadrature and photon-number variances produced by multiple-mode parametric processes. In this paper, formulas are derived for the quadrature and number correlations. The number formulas are used to analyze the properties of basic devices, such as two-mode amplifiers, attenuators and frequency convertors, and composite systems made from these devices, such as cascaded parametric amplifiers and communication links. Amplifiers generate idlers that are correlated with the amplified signals, or correlate pre-existing pairs of modes, whereas attenuators decorrelate pre-existing modes. Both types of device modify the signal-to-noise ratios (SNRs) of the modes on which they act. Amplifiers decrease or increase the mode SNRs, depending on whether they are operated in phase-insensitive (PI) or phase-sensitive (PS) manners, respectively, whereas attenuators always decrease these SNRs. Two-mode PS links are sequences of transmission fibers (attenuators) followed by two-mode PS amplifiers. Not only do these PS links have noise figures that are 6-dB lower than those of the corresponding PI links, they also produce idlers that are (almost) completely correlated with the signals. By detecting the signals and idlers, one can eliminate the effects of electronic noise in the detectors.

Parametric study of minimum converter loss in an energy-storage dc-to-dc converter

NASA Technical Reports Server (NTRS)

Wong, R. C.; Owen, H. A., Jr.; Wilson, T. G.

1982-01-01

Through a combination of analytical and numerical minimization procedures, a converter design that results in the minimum total converter loss (including core loss, winding loss, capacitor and energy-storage-reactor loss, and various losses in the semiconductor switches) is obtained. Because the initial phase involves analytical minimization, the computation time required by the subsequent phase of numerical minimization is considerably reduced in this combination approach. The effects of various loss parameters on the optimum values of the design variables are also examined.

Optical apparatus for conversion of whispering-gallery modes into a free space gaussian like beam

DOEpatents

Stallard, Barry W.; Makowski, Michael A.; Byers, Jack A.

1992-01-01

An optical converter for efficient conversion of millimeter wavelength whispering-gallery gyrotron output into a linearly polarized, free-space Gaussian-like beam. The converter uses a mode-converting taper and three mirror optics. The first mirror has an azimuthal tilt to eliminate the k.sub..phi. component of the propagation vector of the gyrotron output beam. The second mirror has a twist reflector to linearly polarize the beam. The third mirror has a constant phase surface so the converter output is in phase.

Comparative characterization of digestate versus pig slurry and cow manure - Chemical composition and effects on soil microbial activity.

PubMed

Risberg, Kajsa; Cederlund, Harald; Pell, Mikael; Arthurson, Veronica; Schnürer, Anna

2017-03-01

The growing number of biogas plants in Europe has resulted in increased production of nutrient-rich digestate with great potential as fertilizer for arable land. The nutrient composition of digestate varies with the substrate treated in the biogas plant and may contain compounds that stimulate or inhibit soil microbial activity. This study compared 20 digestates (D) with 10 pig slurries (PS) and 10 cow manures (CM) regarding their chemical content and their effect on soil microbial activities, i.e. potential ammonia oxidation rate (PAO) and soil respiration. The results showed no significant differences within the D group when divided based on substrate type. i.e. manure dominated vs. other organic waste materials in any of the tests. In general D contained significantly higher concentrations of ammonium while the concentrations of total carbon and volatile fatty acids were higher in PS and CM than in D. The D showed both stimulating and inhibiting effects on PAO, while all CM and all PS except one showed inhibiting effects on PAO. However, PAO activity was negatively correlated with the content of volatile fatty acids in the residues indicating that these compounds may be the cause of the inhibition. The maximum respiration activity (h peakmax ) was lower and the time point for the maximum respiration activity (t peakmax ) occurred earlier for D compared with CM and PS. This earlier peak time could be indicative of a high proportion of easily degradable carbon in D compared with PS and CM. However, the utilization rate of carbon, i.e. the proportion of added organic C converted to CO 2 -C during 12days, did not differ significantly between D, PS and CM, indicating that overall carbon quality in the different fertilizers was still roughly comparable. In short, our results suggest that digestates were different compared with PS and CM but without posing a higher risk with respect to their impact on soil microbial activity. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Energetic electron bursts in the plasma sheet and their relation with BBFs

NASA Astrophysics Data System (ADS)

Duan, A. Y.; Cao, J. B.; Dunlop, M.; Wang, Z. Q.

2014-11-01

We studied energetic electron bursts (EEBs) (40-250 keV) in the plasma sheet (PS) and their relation to bursty bulk flows (BBFs) using the data recorded by Cluster from 2001 to 2009. The EEBs in the PS can be classified into four types. Three types of EEBs are dispersionless, including EEBs accompanied with BBFs (V > 250 km/s) but without dipolarization front (DF); EEBs accompanied with both dipolarization front (DF) and BBF; and EEBs accompanied with DF and fast flow with V < 250 km/s. One type of EEB, i.e., EEBs not accompanied with BBFs and DFs, is dispersed. The energetic electrons (40-130 keV) can be easily transported earthward by BBFs due to the strong dawn-dusk electric field embedded in BBFs. The DFs in BBFs can produce energetic electrons (40 to 250 keV). For the EEBs with DF and BBFs, the superposed epoch analyses show that the increase of energetic electron flux has two phases: gradual increase phase before DF and rapid increase phase concurrent with DF. In the PS around x = -18 RE, 60%-70% of EEBs are accompanied with BBFs, indicating that although hitherto there have been various acceleration mechanisms of energetic electrons, most of the energetic electrons in the PS are related with magnetic reconnection, and they are produced either directly by magnetic reconnection or indirectly by the DFs within BBFs. In the BBF's braking region of -12 RE < x < -10 RE, 20% of EEBs are accompanied with BBFs. The corresponding ratio between EEBs and BBFs shows a dawn-dusk asymmetry.

Frequency domain, time-resolved and spectroscopic investigations of photosensitizers encapsulated in liposomal phantoms

NASA Astrophysics Data System (ADS)

Mermut, Ozzy; Bouchard, Jean-Pierre; Cormier, Jean-Francois; Diamond, Kevin R.; Noiseux, Isabelle; Vernon, Marcia L.; Patterson, Michael S.

2007-07-01

A broadband frequency domain fluorescence lifetime system (from ns to ms time scale) has been developed to study the photochemical and photodynamic behavior of model, well-controlled photosensitizer-encapsulating liposomes. Liposomes are known to be efficient and selective photosensitizer (PS) drug delivery vesicles, however, their chemical and physical effects on the photochemical properties of the photosensitizer have not been well characterized. The liposomes employed in this study (both blank and photosensitizer-complexed) were characterized to determine their: a) size distribution (dynamic light scattering), b) image (scanning electron microscope, confocal fluorescence microscopy), c) concentration of particles (flow cytometry), d) temperature-dependant phase transition behavior (differential scanning calorimetry, and e) spectrofluorescent spectrophotometric properties, e.g. aggregation, in the confined environment. The fluorescence decay behavior of two families of encapsulated photosensitizers, di-and tetrasulfonated metallophthalocyanines, and 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH), has been examined as a function of the liposome's physical properties (size-scale, distribution and concentration of scatterer) and the impact of the photosensitizer spatial confinement determined. It is found that the achievable size range and distribution of the PS-liposomes is controlled by the chemical nature of the PS for large liposomes (1000 nm), and is PS independent for small PS-liposomes (~140nm). The lifetime decay behavior was studied for all three photosensitizer-liposome systems and compared before and after confinement. We found the nature of the decay to be similar before and after encapsulation for the sulfonated phthalocyanines containing ionic moieties (primarily monoexponential) but not for HPPH. In the latter, the decay transitioned from multi- to monoexponential decay upon localizing lypophilic HPPH to the liposomal membrane. This behavior was confirmed by obtaining a similar change in lifetime response with an independent timedomain system. We also varied the environment in temperature and oxygen content to examine the effects on the fluorescent lifetimes of the liposomal complexes. The fluorescence decay of all three PS-containing liposomes showed that the local spatial confinement of PS (dictated by the PS chemistry) into different domains within the liposome directly controls the temperature-response. Membrane-bound photosensitizers were less sensitive to temperature effects as illustrated by the decay dynamics observed in solu, that is, they developed a unique decay behavior that correlated with the phase transition of the membrane. The fluorescent lifetime of PS-encapsulated liposomes in deoxygenated environments, relevant to oxygen independent type I phototoxicity, was also probed in the frequency-domain revealing that liposome-confined PS display very different trends than those observed in solu.

Compensation of PVT Variations in ToF Imagers with In-Pixel TDC

PubMed Central

Vornicu, Ion; Carmona-Galán, Ricardo; Rodríguez-Vázquez, Ángel

2017-01-01

The design of a direct time-of-flight complementary metal-oxide-semiconductor (CMOS) image sensor (dToF-CIS) based on a single-photon avalanche-diode (SPAD) array with an in-pixel time-to-digital converter (TDC) must contemplate system-level aspects that affect its overall performance. This paper provides a detailed analysis of the impact of process parameters, voltage supply, and temperature (PVT) variations on the time bin of the TDC array. Moreover, the design and characterization of a global compensation loop is presented. It is based on a phase locked loop (PLL) that is integrated on-chip. The main building block of the PLL is a voltage-controlled ring-oscillator (VCRO) that is identical to the ones employed for the in-pixel TDCs. The reference voltage that drives the master VCRO is distributed to the voltage control inputs of the slave VCROs such that their multiphase outputs become invariant to PVT changes. These outputs act as time interpolators for the TDCs. Therefore the compensation scheme prevents the time bin of the TDCs from drifting over time due to the aforementioned factors. Moreover, the same scheme is used to program different time resolutions of the direct time-of-flight (ToF) imager aimed at 3D ranging or depth map imaging. Experimental results that validate the analysis are provided as well. The compensation loop proves to be remarkably effective. The spreading of the TDCs time bin is lowered from: (i) 20% down to 2.4% while the temperature ranges from 0 °C to 100 °C; (ii) 27% down to 0.27%, when the voltage supply changes within ±10% of the nominal value; (iii) 5.2 ps to 2 ps standard deviation over 30 sample chips, due to process parameters’ variation. PMID:28486405

Compensation of PVT Variations in ToF Imagers with In-Pixel TDC.

PubMed

Vornicu, Ion; Carmona-Galán, Ricardo; Rodríguez-Vázquez, Ángel

2017-05-09

The design of a direct time-of-flight complementary metal-oxide-semiconductor (CMOS) image sensor (dToF-CIS) based on a single-photon avalanche-diode (SPAD) array with an in-pixel time-to-digital converter (TDC) must contemplate system-level aspects that affect its overall performance. This paper provides a detailed analysis of the impact of process parameters, voltage supply, and temperature (PVT) variations on the time bin of the TDC array. Moreover, the design and characterization of a global compensation loop is presented. It is based on a phase locked loop (PLL) that is integrated on-chip. The main building block of the PLL is a voltage-controlled ring-oscillator (VCRO) that is identical to the ones employed for the in-pixel TDCs. The reference voltage that drives the master VCRO is distributed to the voltage control inputs of the slave VCROs such that their multiphase outputs become invariant to PVT changes. These outputs act as time interpolators for the TDCs. Therefore the compensation scheme prevents the time bin of the TDCs from drifting over time due to the aforementioned factors. Moreover, the same scheme is used to program different time resolutions of the direct time-of-flight (ToF) imager aimed at 3D ranging or depth map imaging. Experimental results that validate the analysis are provided as well. The compensation loop proves to be remarkably effective. The spreading of the TDCs time bin is lowered from: (i) 20% down to 2.4% while the temperature ranges from 0 °C to 100 °C; (ii) 27% down to 0.27%, when the voltage supply changes within ±10% of the nominal value; (iii) 5.2 ps to 2 ps standard deviation over 30 sample chips, due to process parameters' variation.

Calcium signaling, excitability, and synaptic plasticity defects in a mouse model of Alzheimer's disease.

PubMed

Zhang, Hua; Liu, Jie; Sun, Suya; Pchitskaya, Ekaterina; Popugaeva, Elena; Bezprozvanny, Ilya

2015-01-01

Alzheimer's disease (AD) and aging result in impaired ability to store memories, but the cellular mechanisms responsible for these defects are poorly understood. Presenilin 1 (PS1) mutations are responsible for many early-onset familial AD (FAD) cases. The phenomenon of hippocampal long-term potentiation (LTP) is widely used in studies of memory formation and storage. Recent data revealed long-term LTP maintenance (L-LTP) is impaired in PS1-M146V knock-in (KI) FAD mice. To understand the basis for this phenomenon, in the present study we analyzed structural synaptic plasticity in hippocampal cultures from wild type (WT) and KI mice. We discovered that exposure to picrotoxin induces formation of mushroom spines in both WT and KI cultures, but the maintenance of mushroom spines is impaired in KI neurons. This maintenance defect can be explained by an abnormal firing pattern during the consolidation phase of structural plasticity in KI neurons. Reduced frequency of neuronal firing in KI neurons is caused by enhanced calcium-induced calcium release (CICR), enhanced activity of calcium-activated potassium channels, and increased afterhyperpolarization. As a result, "consolidation" pattern of neuronal activity converted to "depotentiation" pattern of neuronal activity in KI neurons. Consistent with this model, we demonstrated that pharmacological inhibitors of CICR (dantrolene), of calcium-activated potassium channels (apamin), and of calcium-dependent phosphatase calcineurin (FK506) are able to rescue structural plasticity defects in KI neurons. Furthermore, we demonstrate that incubation with dantrolene or apamin also rescued L-LTP defects in KI hippocampal slices, suggesting a role for a similar mechanism. This proposed mechanism may be responsible for memory defects in AD but also for age-related memory decline.

Determination of characteristics of degenerative joint disease using optical coherence tomography and polarization sensitive optical coherence tomography.

PubMed

Xie, Tuqiang; Guo, Shuguang; Zhang, Jun; Chen, Zhongping; Peavy, George M

2006-10-01

Previous studies have demonstrated that optical coherence tomography (OCT) could be used to delineate alterations in the microstructure of cartilage, and have suggested that changes in the polarization state of light as detected by OCT could provide information on the birefringence properties of articular cartilage as influenced by disease. In this study we have used both OCT and polarization sensitive optical coherence tomography (PS-OCT) technologies to evaluate normal and abnormal bovine articular cartilage according to established structural, organizational, and birefringent characteristics of degenerative joint disease (DJD) in order to determine if this technology can be used to differentiate various stages of DJD as a minimally invasive imaging tool. Fresh bovine femoral-tibial joints were obtained from an abattoir, and 45 cartilage specimens were harvested from 8 tibial plateaus. Whole ex vivo specimens of normal and degenerative articular cartilage were imaged by both OCT and PS-OCT, then fixed and processed for histological evaluation. OCT/PS-OCT images and corresponding histology sections of each specimen were scored according to a modified Mankin structural grading scale and compared. OCT and PS-OCT imaging allowed structural evaluation of intact articular cartilage along a 6 mm surface length to a depth of 2 mm with a transverse resolution of 12 microm and an axial resolution of 10 microm. The OCT and PS-OCT images demonstrated characteristic alterations in the structure of articular cartilage with a high correlation to histological evaluation (kappa = 0.776). The OCT images were able to demonstrate early to advanced structural changes of articular cartilage while the optical phase retardation images obtained by PS-OCT imaging were able to discriminate areas where disorganization of the cartilage matrix was present, however, these characteristics are much different than those reported where OCT images alone were used to characterize tissue birefringence. No evidence of differences in OCT or PS-OCT images were detected between specimens of similar structural characteristics where proteoglycan was judged present or absent by safranin-O Fast Green staining. The combined use of OCT and PS-OCT technologies to obtain images from a single system is able to demonstrate and discriminate between characteristics of very early stages of surface irregularities not previously reported for OCT imaging, to deep clefts and collagen matrix disorganization for tissue at depths of up to 2 mm with good correlation to histology. PS-OCT and accumulated optical phase retardation images of articular cartilage as constructed from alterations in Stokes vector parameters appear to give a valuable but different assessment of alterations in tissue birefringence and organization than have been reported for OCT images obtained with the use of polarized or non-polarized light sources. This is the first time that alterations in the polarization state of light reflected from within the tissue have been demonstrated to be consistent with changes observed in the orientation and organization of the collagen matrix in advanced stages of DJD. The degree of phase transformation of light reflected from within the tissue as determined by PS-OCT imaging does not appear to be altered by the presence or absence of proteoglycan.

Testing directed evolution strategies for space exploration: genetic modification of photosystem II to increase stress tolerance under space conditions

NASA Astrophysics Data System (ADS)

Bertalan, I.; Giardi, M. T.; Johanningmeier, U.

Plants and many microorganisms are able to convert and store solar energy in chemical bonds by a process called photosynthesis They remove CO 2 from the atmosphere fix it as carbohydrate and simultaneously evolve oxygen Oxygen evolution is of supreme relevance for all higher life forms and results from the splitting of water molecules This process is catalyzed by the so called photosystem II PSII complex and represents the very beginning of biomass production PS II is also a central point of regulation being responsive to various physical and physiological parameters Complex space radiation is damaging PS II and reduces photosynthetic efficiency Thus bioregenerative life-support systems are severely disturbed at this point Genetic manipulation of photosynthesis checkpoints offer the possibility to adjust biomass and oxygen production to changing environmental conditions As the photosynthetic apparatus has adapted to terrestrial and not to space conditions we are trying to adapt a central and particularly stress-susceptible element of the photosynthesis apparatus - the D1 subunit of PS II - to space radiation by a strategy of directed evolution The D1 subunit together with its sister subunit D2 form the reaction centre of PS II D1 presents a central weak point for radiation energy that hits the chloroplast We have constructed a mutant of the green alga Chlamydomonas reinhardtii with a defect D1 protein This mutant is easily transformable with D1-encoding PCR fragments without purification and cloning steps 1 When

Effect of surfactants or a water soluble polymer on the crystal transition of clarithromycin during a wet granulation process.

PubMed

Nozawa, Kenji; Iwao, Yasunori; Noguchi, Shuji; Itai, Shigeru

2015-11-10

To generate products containing a stable form of clarithromycin (CAM) (form II) regardless of the initial crystal form of CAM or type of granulation solvent, the effects of five surfactants, or a water-soluble polymer (macrogol 400) were determined on the crystal transition of CAM. The metastable form (form I) was kneaded with water, after adding surfactants, or a water-soluble polymer. Form II was also kneaded with ethanol, after adding the same additives. The resulting samples were analyzed by powder X-ray diffraction. Form I was completely converted to form II by a wet granulation using water with additives bearing polyoxyethylene chains such as polysorbate 80 (PS80), polyoxyl 40 stearate or macrogol 400. The granulation of the form II using ethanol with these additives did not result in a crystal transition to form I. Furthermore, CAM tablets were manufactured using granules with PS80, and these crystal forms and dissolution behaviors were investigated. As a result, the wet granulation of CAM with PS80 gave CAM tablets containing only form II and PS80 did not have any adverse effects on tablet characteristics. Therefore, these data suggests that the crystal form of CAM can be controlled to be form II using a wet granulation process with additives bearing polyoxyethylene chains regardless of the initial crystal form of CAM or type of granulation solvent. Copyright © 2015 Elsevier B.V. All rights reserved.

Compact pulse width modulation circuitry for silicon photomultiplier readout.

PubMed

Bieniosek, M F; Olcott, P D; Levin, C S

2013-08-07

The adoption of solid-state photodetectors for positron emission tomography (PET) system design and the interest in 3D interaction information from PET detectors has lead to an increasing number of readout channels in PET systems. To handle these additional readout channels, PET readout electronics should be simplified to reduce the power consumption, cost, and size of the electronics for a single channel. Pulse-width modulation (PWM), where detector pulses are converted to digital pulses with width proportional to the detected photon energy, promises to simplify PET readout by converting the signals to digital form at the beginning of the processing chain, and allowing a single time-to-digital converter to perform the data acquisition for many channels rather than routing many analogue channels and digitizing in the back end. Integrator based PWM systems, also known as charge-to-time converters (QTCs), are especially compact, reducing the front-end electronics to an op-amp integrator with a resistor discharge, and a comparator. QTCs, however, have a long dead-time during which dark count noise is integrated, reducing the output signal-to-noise ratio. This work presents a QTC based PWM circuit with a gated integrator that shows performance improvements over existing QTC based PWM. By opening and closing an analogue switch on the input of the integrator, the circuit can be controlled to integrate only the portions of the signal with a high signal-to-noise ratio. It also allows for multiplexing different detectors into the same PWM circuit while avoiding uncorrelated noise propagation between photodetector channels. Four gated integrator PWM circuits were built to readout the spatial channels of two position sensitive solid-state photomultiplier (PS-SSPM). Results show a 4 × 4 array 0.9 mm × 0.9 mm × 15 mm of LYSO crystals being identified on the 5 mm × 5 mm PS-SSPM at room temperature with no degradation for twofold multiplexing. In principle, much larger multiplexing ratios are possible, limited only by count rate issues.

Multi-speed multi-phase resolver converter

NASA Technical Reports Server (NTRS)

Alhorn, Dean (Inventor); Howard, David (Inventor)

1994-01-01

A multiphase converter circuit generates a plurality of sinusoidal outputs of displaced phase and given speed value from the output of an angular resolver system attachable to a motor excited by these multi-phase outputs, the resolver system having a lower speed value than that of the motor. The angular resolver system provides in parallel format sequential digital numbers indicative of the amount of rotation of the shaft of an angular position sensor associated with the angular resolver system. These numbers are used to excite simultaneously identical addresses of a plurality of addressable memory systems, each memory system having stored therein at sequential addresses sequential values of a sinusoidal wavetrain of a given number of sinusoids. The stored wavetrain values represent sinusoids displaced from each other in phase according to the number of output phases desired. A digital-to-analog converter associated with each memory system converts each accessed word to a corresponding analog value to generate attendant to rotation of the angular resolver a sinusoidal wave of proper phase at each of the plurality of outputs. By properly orienting the angular resolver system with respect to the rotor of the motor, essentially ripple-free torque is supplied to the rotor. The angular resolver system may employ an analog resolver feeding an integrated circuit resolver-to-digital converter to produce the requisite digital values serving as addresses. Alternative versions employing incremental or absolute encoders are also described.

Multi-speed multi-phase resolver converter

NASA Technical Reports Server (NTRS)

Alhorn, Dean C. (Inventor); Howard, David E. (Inventor)

1995-01-01

A multiphase converter circuit generates a plurality of sinusoidal outputs of displaced phase and given speed value from the output of an angular resolver system attachable to a motor excited by these multi-phase outputs, the resolver system having a lower speed value than that of the motor. The angular resolver system provides in parallel format sequential digital numbers indicative of the amount of rotation of the shaft of an angular position sensor associated with the angular resolver system. These numbers are used to excite simultaneously identical addresses of a plurality of addressable memory systems, each memory system having stored therein at sequential addresses sequential values of a sinusoidal wavetrain of a given number of sinusoids. The stored wavetrain values represent sinusoids displaced from each other in phase according to the number of output phases desired. A digital-to-analog converter associated with each memory system converts each accessed word to a corresponding analog value to generate attendant to rotation of the angular resolver a sinusoidal wave of proper phase at each of the plurality of outputs. By properly orienting the angular resolver system with respect to the rotor of the motor, essentially ripple-free torque is supplied to the rotor. The angular resolver system may employ an analog resolver feeding an integrated circuit resolver-to-digital converter to produce the requisite digital values serving as addresses. Alternative versions employing incremental or absolute encoders are also described.

Radiation-hardened-by-design clocking circuits in 0.13-μm CMOS technology

NASA Astrophysics Data System (ADS)

You, Y.; Huang, D.; Chen, J.; Gong, D.; Liu, T.; Ye, J.

2014-01-01

We present a single-event-hardened phase-locked loop for frequency generation applications and a digital delay-locked loop for DDR2 memory interface applications. The PLL covers a 12.5 MHz to 500 MHz frequency range with an RMS Jitter (RJ) of 4.70-pS. The DLL operates at 267 MHz and has a phase resolution of 60-pS. Designed in 0.13-μm CMOS technology, the PLL and the DLL are hardened against SEE for charge injection of 250 fC. The PLL and the DLL consume 17 mW and 22 mW of power under a 1.5 V power supply, respectively.

Phase-shifting point diffraction interferometer focus-aid enhanced mask

DOEpatents

Naulleau, Patrick

2000-01-01

A phase-shifting point diffraction interferometer system (PS/PDI) employing a PS/PDI mask that includes a PDI focus aid is provided. The PDI focus aid mask includes a large or secondary reference pinhole that is slightly displaced from the true or primary reference pinhole. The secondary pinhole provides a larger capture tolerance for interferometrically performing fine focus. With the focus-aid enhanced mask, conventional methods such as the knife-edge test can be used to perform an initial (or rough) focus and the secondary (large) pinhole is used to perform interferometric fine focus. Once the system is well focused, high accuracy interferometry can be performed using the primary (small) pinhole.

Bulk and monolayer ordering of block copolymer blends

NASA Astrophysics Data System (ADS)

Onikoyi, Adetunji J.

The control of the nanoscale structure or morphology of a block copolymer is a desired goal for nanolithography applications. In this work, we are particularly interested in providing guides for controlling domain size, domain shape and defect densities in block copolymers and their blends for thin film applications. To reach this goal, a sphere forming PS-b-P2VP (having a PS majority block) and its blends with PS homopolymer or cylinder forming PS-b-P2VP are studied in both the bulk and thin films. Structure characterization is performed using a variety of experimental techniques including small angle X-ray scattering, scanning force microscopy and transmission electron microscopy. In the bulk, the spherical domains of the pure, sphere forming PS-b-P2VP arrange on a BCC lattice. On adding PS homopolymer (hPS), the lattice parameter of the BCC spheres increases, while the order-to-disorder temperature (ODT) of the BCC lattice simultaneously decreases. At a given hPS composition, the use of larger sized hPS leads to larger increases in the lattice parameter and larger decreases in the ODT. In bulk blends of cylinder forming PS-b-P2VP with sphere forming PS-b-P2VP, the ordered morphology changes (e.g., cylindrical morphology → coexisting spherical and cylindrical morphologies → spherical morphology) as the sphere forming PS-b-P2VP volume fraction phis increases, while the ODT of the cylindrical morphology decreases. The phase boundaries of these morphologies in monolayers shift to lower phis compared to those of the bulk, apparently caused by a selective adsorption of the cylindrical PS-b-P2VP to form a brush on the substrate. This selective adsorption leads to a preference for spherical domains in diamond-shaped lateral confinements when cylindrical domains are stabilized outside the confinements on the same substrate. Finally, we explore the use of graphoepitaxy to order monolayers of sphere forming PS-b-P2VP and its blends with hPS. The probability of forming isolated dislocations, or of adding (or removing) a full row of spherical domains, in diamond-shaped lateral confinements is shown to be higher when the well size is incommensurate with the lattice parameter. Square-shaped lateral confinement leads to a preference for square sphere packing if the PS-b-P2VP is blended with appropriate amounts of hPS.

Pressure Monitoring Using Hybrid fs/ps Rotational CARS

NASA Technical Reports Server (NTRS)

Kearney, Sean P.; Danehy, Paul M.

2015-01-01

We investigate the feasibility of gas-phase pressure measurements at kHz-rates using fs/ps rotational CARS. Femtosecond pump and Stokes pulses impulsively prepare a rotational Raman coherence, which is then probed by a high-energy 6-ps pulse introduced at a time delay from the Raman preparation. Rotational CARS spectra were recorded in N2 contained in a room-temperature gas cell for pressures from 0.1 to 3 atm and probe delays ranging from 10-330 ps. Using published self-broadened collisional linewidth data for N2, both the spectrally integrated coherence decay rate and the spectrally resolved decay were investigated as means for detecting pressure. Shot-averaged and single-laser-shot spectra were interrogated for pressure and the accuracy and precision as a function of probe delay and cell pressure are discussed. Single-shot measurement accuracies were within 0.1 to 6.5% when compared to a transducer values, while the precision was generally between 1% and 6% of measured pressure for probe delays of 200 ps or more, and better than 2% as the delay approached 300 ps. A byproduct of the pressure measurement is an independent but simultaneous measurement of the gas temperature.

Sulfate radical degradation of acetaminophen by novel iron-copper bimetallic oxidation catalyzed by persulfate: Mechanism and degradation pathways

NASA Astrophysics Data System (ADS)

Zhang, Yuanchun; Zhang, Qian; Hong, Junming

2017-11-01

A novel iron coupled copper oxidate (Fe2O3@Cu2O) catalyst was synthesized to activate persulfate (PS) for acetaminophen (APAP) degradation. The catalysts were characterized via field-emission scanning electron microscopy and energy-dispersive X-ray spectrometry. The effects of the catalyst, PS concentration, catalyst dosage, initial pH, dissolved oxygen were analyzed for treatment optimization. Results indicated that Fe2O3@Cu2O achieved higher efficiency in APAP degradation than Fe2O3/PS and Cu2O/PS systems. The optimal removal efficiency of APAP (90%) was achieved within 40 min with 0.6 g/L PS and 0.3 g/L catalyst. To clarify the mechanism for APAP degradation, intermediates were analyzed with gas chromatography-mass spectrometry. Three possible degradation pathways were identified. During reaction, Cu(I) was found to react with Fe(III) to generate Fe(II), which is the most active phase for PS activation. Through the use of methanol and tert-butyl alcohol (TBA) as radical trappers, SO4rad - was identified as the main radical species that is generated during oxidation.

Operating System For Numerically Controlled Milling Machine

NASA Technical Reports Server (NTRS)

Ray, R. B.

1992-01-01

OPMILL program is operating system for Kearney and Trecker milling machine providing fast easy way to program manufacture of machine parts with IBM-compatible personal computer. Gives machinist "equation plotter" feature, which plots equations that define movements and converts equations to milling-machine-controlling program moving cutter along defined path. System includes tool-manager software handling up to 25 tools and automatically adjusts to account for each tool. Developed on IBM PS/2 computer running DOS 3.3 with 1 MB of random-access memory.

Bandwidth broadening of a graphene-based circular polarization converter by phase compensation.

PubMed

Gao, Xi; Yang, Wanli; Cao, Weiping; Chen, Ming; Jiang, Yannan; Yu, Xinhua; Li, Haiou

2017-10-02

We present a broadband tunable circular polarization converter composed of a single graphene sheet patterned with butterfly-shaped holes, a dielectric spacer, and a 7-layer graphene ground plane. It can convert a linearly polarized wave into a circularly polarized wave in reflection mode. The polarization converter can be dynamically tuned by varying the Fermi energy of the single graphene sheet. Furthermore, the 7-layer graphene acting as a ground plane can modulate the phase of its reflected wave by controlling the Femi energy, which provides constructive interference condition at the surface of the single graphene sheet in a broad bandwidth and therefore significantly broadens the tunable bandwidth of the proposed polarization converter.

Immunogenicity and safety of a new meningococcal A conjugate vaccine in Indian children aged 2-10 years: a phase II/III double-blind randomized controlled trial.

PubMed

Hirve, Siddhivinayak; Bavdekar, Ashish; Pandit, Anand; Juvekar, Sanjay; Patil, Malini; Preziosi, Marie-Pierre; Tang, Yuxiao; Marchetti, Elisa; Martellet, Lionel; Findlow, Helen; Elie, Cheryl; Parulekar, Varsha; Plikaytis, Brian; Borrow, Ray; Carlone, George; Kulkarni, Prasad S; Goel, Akshay; Suresh, Karupothula; Beri, Suresh; Kapre, Subhash; Jadhav, Suresh; Preaud, Jean-Marie; Viviani, Simonetta; LaForce, F Marc

2012-10-05

This study compares the immunogenicity and safety of a single dose of a new meningococcal A conjugate vaccine (PsA-TT, MenAfriVac™, Serum Institute of India Ltd., Pune) against the meningococcal group A component of a licensed quadrivalent meningococcal polysaccharide vaccine (PsACWY, Mencevax ACWY(®), GSK, Belgium) 28 days after vaccination in Indian children. This double-blind, randomized, controlled study included 340 Indian children aged 2-10 years enrolled from August to October 2007; 169 children received a dose of PsA-TT while 171 children received a dose of PsACWY. Intention-to-treat analysis showed that 95.2% of children in PsA-TT group had a ≥4-fold response in serum bactericidal titers (rSBA) 28 days post vaccination as compared to 78.2% in the PsACWY group. A significantly higher rSBA GMT (11,209, 95%CI 9708-12,942) was noted in the PsA-TT group when compared to PsACWY group (2838, 95%CI 2368-3401). Almost all children in both vaccine groups had a ≥4-fold response in group A-specific IgG concentration but the IgG GMC was significantly greater in the PsA-TT group (89.1 μg/ml, 95%CI 75.5-105.0) when compared to the PsACWY group (15.3 μg/ml, 95%CI 12.3-19.2). Local and systemic reactions during the 4 days after immunization were similar for both vaccine groups except for tenderness (30.2% in PsA-TT group vs 12.3% in PsACWY group). None of the adverse events or serious adverse events was related to the study vaccines. We conclude that MenAfriVac™ is well tolerated and significantly more immunogenic when compared to a licensed polysaccharide vaccine, in 2-to-10-year-old Indian children. Copyright © 2012 Elsevier Ltd. All rights reserved.

Alectinib for Patients with ALK Rearrangement-Positive Non-Small Cell Lung Cancer and a Poor Performance Status (Lung Oncology Group in Kyushu 1401).

PubMed

Iwama, Eiji; Goto, Yasushi; Murakami, Haruyasu; Harada, Taishi; Tsumura, Shinsuke; Sakashita, Hiroyuki; Mori, Yoshiaki; Nakagaki, Noriaki; Fujita, Yuka; Seike, Masahiro; Bessho, Akihiro; Ono, Manabu; Okazaki, Akihito; Akamatsu, Hiroaki; Morinaga, Ryotaro; Ushijima, Shinichiro; Shimose, Takayuki; Tokunaga, Shoji; Hamada, Akinobu; Yamamoto, Nobuyuki; Nakanishi, Yoichi; Sugio, Kenji; Okamoto, Isamu

2017-07-01

Alectinib has shown marked efficacy and safety in patients with anaplastic lymphoma receptor tyrosine kinase gene (ALK) rearrangement-positive NSCLC and a good performance status (PS). It has remained unclear whether alectinib might also be beneficial for such patients with a poor PS. Eligible patients with advanced ALK rearrangement-positive NSCLC and a PS of 2 to 4 received alectinib orally at 300 mg twice daily. The primary end point of the study was objective response rate (ORR), and the most informative secondary end point was rate of PS improvement. Between September 2014 and December 2015, 18 patients were enrolled in this phase II study. Of those patients, 12, five, and one had a PS of 2, 3, or 4, respectively, whereas four patients had received prior crizotinib treatment. The ORR was 72.2% (90% confidence interval: 52.9-85.8%). The ORR did not differ significantly between patients with a PS of 2 and those with a PS of 3 or higher (58.3% and 100%, respectively [p = 0.114]). The PS improvement rate was 83.3% (90% confidence interval: 64.8-93.1%, p < 0.0001), with the frequency of improvement to a PS of 0 or 1 being 72.2%. The median progression-free survival was 10.1 months. Toxicity was mild, with the frequency of adverse events of grade 3 or higher being low. Neither dose reduction nor withdrawal of alectinib because of toxicity was necessary. Alectinib is a treatment option for patients with ALK rearrangement-positive NSCLC and a poor PS. Copyright © 2017 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

A Close Loop Low-Power and High Speed 130 nm CMOS Sample and Hold Circuit Based on Switched Capacitor for ADC Module

NASA Astrophysics Data System (ADS)

Nasir, Z.; Ruslan, S. H.

2017-08-01

A sample and hold (S/H) block is typically used as an analogue to digital interface in the analogue to digital converter (ADC) system. Since ADC is widely used in processing signals, the power consumption of the ADC must be lowered to conserve energy. Therefore the S/H circuit must be of a low powered too. Sampling phase and hold phase are the two phases of the operation cycle of the S/H circuit. Switched capacitor (SC) techniques have been developed in order to allow the integration on a single silicon chip of both digital and analogue functions. By controlling switches around the SC, the SC circuit works by passing charge into and out of a capacitor. SC circuits are suitable for on chip implementations because they replace a resistor with switches and capacitors. In this research, a closed-loop sample and hold circuit based on SC is designed and simulated with Cadence EDA tools. The schematic, layout, and simulation of the circuit is done using generic Silterra 130 nm technology file. All the analysis is done using Virtuoso Analog Design Environment. Layout and schematic are drawn using Virtuoso Schematic Editor and Virtuoso Layout Editor, Calibre is used for post layout simulation. The closed loop S/H circuit based on SC is successfully designed and able to sample and hold the analogue input waveform. The power consumption of the circuit is 0.919 mW and the propagation delay is 64.96 ps.

Power flow controller with a fractionally rated back-to-back converter

DOEpatents

Divan, Deepakraj M.; Kandula, Rajendra Prasad; Prasai, Anish

2016-03-08

A power flow controller with a fractionally rated back-to-back (BTB) converter is provided. The power flow controller provide dynamic control of both active and reactive power of a power system. The power flow controller inserts a voltage with controllable magnitude and phase between two AC sources at the same frequency; thereby effecting control of active and reactive power flows between the two AC sources. A transformer may be augmented with a fractionally rated bi-directional Back to Back (BTB) converter. The fractionally rated BTB converter comprises a transformer side converter (TSC), a direct-current (DC) link, and a line side converter (LSC). By controlling the switches of the BTB converter, the effective phase angle between the two AC source voltages may be regulated, and the amplitude of the voltage inserted by the power flow controller may be adjusted with respect to the AC source voltages.

Phase synchronization based minimum spanning trees for analysis of financial time series with nonlinear correlations

NASA Astrophysics Data System (ADS)

Radhakrishnan, Srinivasan; Duvvuru, Arjun; Sultornsanee, Sivarit; Kamarthi, Sagar

2016-02-01

The cross correlation coefficient has been widely applied in financial time series analysis, in specific, for understanding chaotic behaviour in terms of stock price and index movements during crisis periods. To better understand time series correlation dynamics, the cross correlation matrices are represented as networks, in which a node stands for an individual time series and a link indicates cross correlation between a pair of nodes. These networks are converted into simpler trees using different schemes. In this context, Minimum Spanning Trees (MST) are the most favoured tree structures because of their ability to preserve all the nodes and thereby retain essential information imbued in the network. Although cross correlations underlying MSTs capture essential information, they do not faithfully capture dynamic behaviour embedded in the time series data of financial systems because cross correlation is a reliable measure only if the relationship between the time series is linear. To address the issue, this work investigates a new measure called phase synchronization (PS) for establishing correlations among different time series which relate to one another, linearly or nonlinearly. In this approach the strength of a link between a pair of time series (nodes) is determined by the level of phase synchronization between them. We compare the performance of phase synchronization based MST with cross correlation based MST along selected network measures across temporal frame that includes economically good and crisis periods. We observe agreement in the directionality of the results across these two methods. They show similar trends, upward or downward, when comparing selected network measures. Though both the methods give similar trends, the phase synchronization based MST is a more reliable representation of the dynamic behaviour of financial systems than the cross correlation based MST because of the former's ability to quantify nonlinear relationships among time series or relations among phase shifted time series.

Photocatalytic degradation of polystyrene plastic under fluorescent light.

PubMed

Shang, Jing; Chai, Ming; Zhu, Yongfa

2003-10-01

Plastic is used widely all over the world, due to the fact that it is low cost, is easily processable, and has lightweight properties. However, the hazard of discarding waste plastic, so-called "white pollution", is becoming more and more severe. In this paper, solid-phase photocatalytic degradation of polystyrene (PS) plastic, one of the most common commercial plastics, over copper phthalocyanine (CuPc) sensitized TiO2 photocatalyst (TiO2/CuPc) has been investigated under fluorescent light irradiation in the air. UV-vis spectra show that TiO2/CuPc extends its photoresponse range to visible light, contrasting to only UV light absorption of pure TiO2. The PS photodegradation experiments exhibit that higher PS weight loss rate, lower PS average molecular weight, less amount of volatile organic compounds, and more CO2 can be obtained in the system of PS-(TiO2/CuPc), in comparison with the PS-TiO2 system. Therefore, PS photodegradation over TiO2 CuPc composite is more complete and efficient than over pure TiO2, suggesting the potential application of dye-sensitized TiO2 catalyst in the thorough photodegradation of PS plastic under fluorescent light. During the photodegradation of PS plastic, the reactive oxygen species generated on TiO2 or TiO2/CuPc particle surfaces play important roles in chain scission. The present study demonstrates that the combination of polymer plastic with dye-sensitized TiO2 catalyst in the form of thin film is a practical and useful way to photodegrade plastic contaminants in the sunlight.

Tuning excitation laser wavelength for secondary resonance in low-intensity phase-selective laser-induced breakdown spectroscopy for in-situ analytical measurement of nanoaerosols

NASA Astrophysics Data System (ADS)

Xiong, Gang; Li, Shuiqing; Tse, Stephen D.

2018-02-01

In recent years, a novel low-intensity phase-selective laser-induced breakdown spectroscopy (PS-LIBS) technique has been developed for unique elemental-composition identification of aerosolized nanoparticles, where only the solid-phase nanoparticles break down, forming nanoplasmas, without any surrounding gas-phase breakdown. Additional work has demonstrated that PS-LIBS emissions can be greatly enhanced with secondary resonant excitation by matching the excitation laser wavelength with an atomic transition line in the formed nanoplasma, thereby achieving low limits of detection. In this work, a tunable dye laser is employed to investigate the effects of excitation wavelength and irradiance on in-situ PS-LIBS measurements of TiO2 nanoaerosols. The enhancement factor by resonant excitation can be 220 times greater than that for non-resonant cases under similar conditions. Moreover, the emitted spectra are unique for the selected resonant transition lines for a given element, suggesting the potential to make precise phase-selective and analyte-selective measurements of nanoparticles in a multicomponent multiphase system. The enhancement factor by resonant excitation is highly sensitive to excitation laser wavelength, with narrow excitation spectral windows, i.e., 0.012 to 0.023 nm (FWHM, full width at half maximum) for Ti (I) neutral atomic lines, and 0.051 to 0.139 nm (FWHM) for Ti (II) single-ionized atomic lines. Boltzmann analysis of the emission intensities, temporal response of emissions, and emission dependence on excitation irradiance are investigated to understand aspects of the generated nanoplasmas such as temperature, local thermodynamic equilibrium (LTE), and excitation mechanism.

Development of a DC-DC conversion powering scheme for the CMS Phase-1 pixel upgrade

NASA Astrophysics Data System (ADS)

Feld, L.; Fimmers, C.; Karpinski, W.; Klein, K.; Lipinski, M.; Preuten, M.; Rauch, M.; Rittich, D.; Sammet, J.; Wlochal, M.

2014-01-01

A novel powering scheme based on the DC-DC conversion technique will be exploited to power the CMS Phase-1 pixel detector. DC-DC buck converters for the CMS pixel project have been developed, based on the AMIS5 ASIC designed by CERN. The powering system of the Phase-1 pixel detector is described and the performance of the converter prototypes is detailed, including power efficiency, stability of the output voltage, shielding, and thermal management. Results from a test of the magnetic field tolerance of the DC-DC converters are reported. System tests with pixel modules using many components of the future pixel barrel system are summarized. Finally first impressions from a pre-series of 200 DC-DC converters are presented.

Onset of ice VII phase during ps laser pulse propagation through liquid water

NASA Astrophysics Data System (ADS)

Kumar, V. Rakesh; Kiran, P. Prem

2017-01-01

Water dominantly present in liquid state on earth gets transformed to crystalline polymorphs under different dynamic loading conditions. Out of different crystalline phases discovered till date, ice VII is observed to be stable over wide pressure (2-63 GPa) and temperature (>273 K) ranges. The formation of ice VII crystalline structure has been vastly reported during high pressure static compression using diamond anvil cell and propagation of high energy (>50 mJ/pulse) nanosecond laser pulse induced dynamic high pressures through liquid water. We present the onset of ice VII phase at low threshold of 2 mJ/pulse during 30 ps (532 nm, 10 Hz) laser pulse induced shock propagating through liquid water. Role of input pulse energy on the evolution of Stoke's and anti-Stoke's Raman shift of the dominant A1g mode of ice VII, filamentation, free-electrons, plasma shielding is presented. The H-bond network rearrangement, electron ion energy transfer time coinciding with the excitation pulse duration supported by the filamentation and plasma shielding of the ps laser pulses reduced the threshold of ice VII structure formation. Filamentation and the plasma shielding have shown the localized creation and sustenance of ice VII structure in liquid water over 3 mm length and 50 μm area of cross-section.

Speech effort measurement and stuttering: investigating the chorus reading effect.

PubMed

Ingham, Roger J; Warner, Allison; Byrd, Anne; Cotton, John

2006-06-01

The purpose of this study was to investigate chorus reading's (CR's) effect on speech effort during oral reading by adult stuttering speakers and control participants. The effect of a speech effort measurement highlighting strategy was also investigated. Twelve persistent stuttering (PS) adults and 12 normally fluent control participants completed 1-min base rate readings (BR-nonchorus) and CRs within a BR/CR/BR/CR/BR experimental design. Participants self-rated speech effort using a 9-point scale after each reading trial. Stuttering frequency, speech rate, and speech naturalness measures were also obtained. Instructions highlighting speech effort ratings during BR and CR phases were introduced after the first CR. CR improved speech effort ratings for the PS group, but the control group showed a reverse trend. Both groups' effort ratings were not significantly different during CR phases but were significantly poorer than the control group's effort ratings during BR phases. The highlighting strategy did not significantly change effort ratings. The findings show that CR will produce not only stutter-free and natural sounding speech but also reliable reductions in speech effort. However, these reductions do not reach effort levels equivalent to those achieved by normally fluent speakers, thereby conditioning its use as a gold standard of achievable normal fluency by PS speakers.

Discovery of Novel Bacterial Cell-Penetrating Phylloseptins in Defensive Skin Secretions of the South American Hylid Frogs, Phyllomedusa duellmani and Phyllomedusa coelestis

PubMed Central

Yang, Nan; Li, Lei; Wu, Di; Gao, Yitian; Xi, Xinping; Zhou, Mei; Wang, Lei; Chen, Tianbao; Shaw, Chris

2016-01-01

Phylloseptin (PS) peptides, derived from South American hylid frogs (subfamily Phyllomedusinae), have been found to have broad-spectrum antimicrobial activities and relatively low haemolytic activities. Although PS peptides have been identified from several well-known and widely-distributed species of the Phyllomedusinae, there remains merit in their study in additional, more obscure and specialised members of this taxon. Here, we report the discovery of two novel PS peptides, named PS-Du and PS-Co, which were respectively identified for the first time and isolated from the skin secretions of Phyllomedusa duellmani and Phyllomedusa coelestis. Their encoding cDNAs were cloned, from which it was possible to deduce the entire primary structures of their biosynthetic precursors. Reversed-phase high-performance liquid chromatography (RP-HPLC) and tandem mass spectrometry (MS/MS) analyses were employed to isolate and structurally-characterise respective encoded PS peptides from skin secretions. The peptides had molecular masses of 2049.7 Da (PS-Du) and 1972.8 Da (PS-Co). They shared typical N-terminal sequences and C-terminal amidation with other known phylloseptins. The two peptides exhibited growth inhibitory activity against E. coli (NCTC 10418), as a standard Gram-negative bacterium, S. aureus (NCTC 10788), as a standard Gram-positive bacterium and C. albicans (NCPF 1467), as a standard pathogenic yeast, all as planktonic cultures. Moreover, both peptides demonstrated the capability of eliminating S. aureus biofilm. PMID:27589802

Sub-nanometre resolution of atomic motion during electronic excitation in phase-change materials.

PubMed

Mitrofanov, Kirill V; Fons, Paul; Makino, Kotaro; Terashima, Ryo; Shimada, Toru; Kolobov, Alexander V; Tominaga, Junji; Bragaglia, Valeria; Giussani, Alessandro; Calarco, Raffaella; Riechert, Henning; Sato, Takahiro; Katayama, Tetsuo; Ogawa, Kanade; Togashi, Tadashi; Yabashi, Makina; Wall, Simon; Brewe, Dale; Hase, Muneaki

2016-02-12

Phase-change materials based on Ge-Sb-Te alloys are widely used in industrial applications such as nonvolatile memories, but reaction pathways for crystalline-to-amorphous phase-change on picosecond timescales remain unknown. Femtosecond laser excitation and an ultrashort x-ray probe is used to show the temporal separation of electronic and thermal effects in a long-lived (>100 ps) transient metastable state of Ge2Sb2Te5 with muted interatomic interaction induced by a weakening of resonant bonding. Due to a specific electronic state, the lattice undergoes a reversible nondestructive modification over a nanoscale region, remaining cold for 4 ps. An independent time-resolved x-ray absorption fine structure experiment confirms the existence of an intermediate state with disordered bonds. This newly unveiled effect allows the utilization of non-thermal ultra-fast pathways enabling artificial manipulation of the switching process, ultimately leading to a redefined speed limit, and improved energy efficiency and reliability of phase-change memory technologies.

Sub-nanometre resolution of atomic motion during electronic excitation in phase-change materials

DOE PAGES

Mitrofanov, Kirill V.; Fons, Paul; Makino, Kotaro; ...

2016-02-12

Phase-change materials based on Ge-Sb-Te alloys are widely used in industrial applications such as nonvolatile memories, but reaction pathways for crystalline-to-amorphous phase-change on picosecond timescales remain unknown. Femtosecond laser excitation and an ultrashort x-ray probe is used to show the temporal separation of electronic and thermal effects in a long-lived (>100 ps) transient metastable state of Ge 2Sb 2Te 5 with muted interatomic interaction induced by a weakening of resonant bonding. Due to a specific electronic state, the lattice undergoes a reversible nondestructive modification over a nanoscale region, remaining cold for 4 ps. An independent time-resolved x-ray absorption fine structuremore » experiment confirms the existence of an intermediate state with disordered bonds. Furthermore, this newly unveiled effect allows the utilization of non-thermal ultra-fast pathways enabling artificial manipulation of the switching process, ultimately leading to a redefined speed limit, and improved energy efficiency and reliability of phase-change memory technologies.« less

Au/CdS Hybrid Nanoparticles in Block Copolymer Micellar Shells.

PubMed

Koh, Haeng-Deog; Changez, Mohammad; Lee, Jae-Suk

2010-10-18

A polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) micellar structure with a P2VP core containing 5 nm CdS nanoparticles (NPs) and a PS shell formed in toluene that is a good solvent for PS block undergoes the core-shell inversion by excess addition of methanol that is a good solvent for P2VP block. It leads to the formation of micellar shell-embedded CdS NPs in the methanol major phase. The spontaneous crystalline growth of Au NPs on the CdS surfaces positioned at micellar shells without a further reduction process is newly demonstrated. The nanostructure of Au/CdS/PS-b-P2VP hybrid NPs is confirmed by transmission electron microscopy, energy-dispersive X-ray, and UV-Vis absorption. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ps laser pulse induced stimulated Raman scattering of ammonium nitrate dissolved in water

NASA Astrophysics Data System (ADS)

Kumar, V. Rakesh; Kiran, P. Prem

2018-04-01

An intense picosecond laser pulse focused into a liquid medium generates a shock wave in the focal region. This shock wave while propagating into the medium varies the pressure and temperature of the liquid locally leading to the appearance of novel phases which are manifested by the appearance of Raman peaks. We present the phase changes of ammonium nitrate (AN) dissolved in water by studying the forward and backward stimulated Raman Scattering (FSRS and BSRS) signals due to propagation of 30 ps laser pulse induced shockwaves. The dominant peak corresponding to the NO3- symmetric stretching mode is observed with a Raman shift of 1045 cm-1 which represents phase IV of AN with an orthogonal crystalline structure. Apart from this peak, the dominant mode of liquid phase of water with a Raman shift of 3400 cm-1 and an ice VII peak at a Raman shift of 3050 cm-1 confirming the pressure of 10 GPa is observed. The effect of the concentration and input energy on the appearance of the phases will be presented.

Phase-locked-loop-based delay-line-free picosecond electro-optic sampling system

NASA Astrophysics Data System (ADS)

Lin, Gong-Ru; Chang, Yung-Cheng

2003-04-01

A delay-line-free, high-speed electro-optic sampling (EOS) system is proposed by employing a delay-time-controlled ultrafast laser diode as the optical probe. Versatile optoelectronic delay-time controllers (ODTCs) based on modified voltage-controlled phase-locked-loop phase-shifting technologies are designed for the laser. The integration of the ODTC circuit and the pulsed laser diode has replaced the traditional optomechanical delay-line module used in the conventional EOS system. This design essentially prevents sampling distortion from misalignment of the probe beam, and overcomes the difficulty in sampling free-running high-speed transients. The maximum tuning range, error, scanning speed, tuning responsivity, and resolution of the ODTC are 3.9π (700°), <5% deviation, 25-2405 ns/s, 0.557 ps/mV, and ˜1 ps, respectively. Free-running wave forms from the analog, digital, and pulsed microwave signals are sampled and compared with those measured by the commercial apparatus.

Direct and real time probe of photoinduced structure transition in colossal magnetoresistive material

DOE PAGES

Li, Junjie; Wang, Xuan; Zhou, Haidong; ...

2016-07-29

Here, we report a direct and real time measurement of photoinduced structure phase transition in single crystal La 0.84Sr 0.16MnO 3 using femtosecond electron diffraction. The melting of orthorhombic lattice ordering under femtosecond optical excitation is found involving two distinct processes with different time scales, an initial fast melting of orthorhombic phase in about 4 ps and a subsequent slower transformation in 90 ps and longer timescales. Furthermore, the fast process is designated as the initial melting of orthorhombic phase induced by the Mn-O bond change that is most likely driven by the quenching of the dynamic Jahn-Teller distortion followingmore » the photo-excitation. We attribute the slow process to the growing of newly formed structure domain from the photo-excited sites to the neighboring non-excited orthorhombic sites.« less

Amorphization dynamics of Ge{sub 2}Sb{sub 2}Te{sub 5} films upon nano- and femtosecond laser pulse irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siegel, J.; Gawelda, W.; Puerto, D.

2008-01-15

Phase transformations of crystalline Ge{sub 2}Sb{sub 2}Te{sub 5} films upon pulsed laser irradiation have been studied using in situ reflectivity measurements with temporal resolution. Two different configurations allowed point probing with nanosecond temporal resolution and imaging with subpicosecond temporal and micrometer spatial resolution. The role of the pulse duration and laser fluence on the dynamics of the phase change and the degree of amorphization is discussed. Several advantageous features of femtosecond compared to nanosecond laser-induced amorphization are identified. Moreover, a high-resolution study of the amorphization dynamics reveals the onset of amorphization at moderate fluences to occur within {approx}100 ps aftermore » arrival of the laser pulse. At high fluences, amorphization occurs after {approx}430 ps and the molten phase is characterized by an anomalously low reflectivity value, indicative of a state of extreme supercooling.« less

Implementation of Four-Phase Interleaved Balance Charger for Series-Connected Batteries with Power Factor Correction

NASA Astrophysics Data System (ADS)

Juan, Y. L.; Lee, Y. T.; Lee, Y. L.; Chen, L. L.; Huang, M. L.

2017-11-01

A four-phase interleaved balance charger for series-connected batteries with power factor correction is proposed in this dissertation. In the two phases of two buckboost converters, the rectified ac power is firstly converted to a dc link capacitor. In the other two phases of two flyback converters, the rectified ac power is directly converted to charge the corresponding batteries. Additionally, the energy on the leakage inductance of flyback converter is bypassed to the dc link capacitor. Then, a dual-output balance charging circuit is connected to the dc link to deliver the dc link power to charge two batteries in the series-connected batteries module. The constant-current/constant-voltage charging strategy is adopted. Finally, a prototype of the proposed charger with rated power 500 W is constructed. From the experimental results, the performance and validity of the proposed topology are verified. Compared to the conventional topology with passive RCD snubber, the efficiency of the proposed topology is improved about 3% and the voltage spike on the active switch is also reduced. The efficiency of the proposed charger is at least 83.6 % within the CC/CV charging progress.

Generation of human pluripotent stem cell-derived hepatocyte-like cells for drug toxicity screening.

PubMed

Takayama, Kazuo; Mizuguchi, Hiroyuki

2017-02-01

Because drug-induced liver injury is one of the main reasons for drug development failures, it is important to perform drug toxicity screening in the early phase of pharmaceutical development. Currently, primary human hepatocytes are most widely used for the prediction of drug-induced liver injury. However, the sources of primary human hepatocytes are limited, making it difficult to supply the abundant quantities required for large-scale drug toxicity screening. Therefore, there is an urgent need for a novel unlimited, efficient, inexpensive, and predictive model which can be applied for large-scale drug toxicity screening. Human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells are able to replicate indefinitely and differentiate into most of the body's cell types, including hepatocytes. It is expected that hepatocyte-like cells generated from human ES/iPS cells (human ES/iPS-HLCs) will be a useful tool for drug toxicity screening. To apply human ES/iPS-HLCs to various applications including drug toxicity screening, homogenous and functional HLCs must be differentiated from human ES/iPS cells. In this review, we will introduce the current status of hepatocyte differentiation technology from human ES/iPS cells and a novel method to predict drug-induced liver injury using human ES/iPS-HLCs. Copyright © 2016 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

Depth-encoded all-fiber swept source polarization sensitive OCT

PubMed Central

Wang, Zhao; Lee, Hsiang-Chieh; Ahsen, Osman Oguz; Lee, ByungKun; Choi, WooJhon; Potsaid, Benjamin; Liu, Jonathan; Jayaraman, Vijaysekhar; Cable, Alex; Kraus, Martin F.; Liang, Kaicheng; Hornegger, Joachim; Fujimoto, James G.

2014-01-01

Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of conventional OCT and can assess depth-resolved tissue birefringence in addition to intensity. Most existing PS-OCT systems are relatively complex and their clinical translation remains difficult. We present a simple and robust all-fiber PS-OCT system based on swept source technology and polarization depth-encoding. Polarization multiplexing was achieved using a polarization maintaining fiber. Polarization sensitive signals were detected using fiber based polarization beam splitters and polarization controllers were used to remove the polarization ambiguity. A simplified post-processing algorithm was proposed for speckle noise reduction relaxing the demand for phase stability. We demonstrated systems design for both ophthalmic and catheter-based PS-OCT. For ophthalmic imaging, we used an optical clock frequency doubling method to extend the imaging range of a commercially available short cavity light source to improve polarization depth-encoding. For catheter based imaging, we demonstrated 200 kHz PS-OCT imaging using a MEMS-tunable vertical cavity surface emitting laser (VCSEL) and a high speed micromotor imaging catheter. The system was demonstrated in human retina, finger and lip imaging, as well as ex vivo swine esophagus and cardiovascular imaging. The all-fiber PS-OCT is easier to implement and maintain compared to previous PS-OCT systems and can be more easily translated to clinical applications due to its robust design. PMID:25401008

A Randomized Study of Immune Plasma for the Treatment of Severe Influenza

PubMed Central

Beigel, John H.; Tebas, Pablo; Elie-Turenne, Marie-Carmelle; Bajwa, Ednan; Bell, Todd E.; Cairns, Charles B.; Shoham, Shmuel; Deville, Jaime G.; Feucht, Eric; Feinberg, Judith; Luke, Thomas; Raviprakash, Kanakatte; Danko, Janine; O’Neil, Dorothy; Metcalf, Julia A.; King, Karen; Burgess, Timothy H.; Aga, Evgenia; Lane, H. Clifford; Hughes, Michael D.; Davey, Richard T.

2017-01-01

Summary Background Influenza causes significant morbidity and mortality despite currently available treatments. Anecdotal reports suggest plasma with high antibody titers towards influenza may be of benefit in the treatment of severe influenza. Methods We conducted a randomized, open-label, multicenter phase 2 trial at 29 academic medical centers in the United States to assess the safety and efficacy of anti-influenza plasma with hemagglutination inhibition (HAI) antibody titers of ≥ 1:80 to the infecting strain. Hospitalized children and adults (including pregnant women) with severe influenza A or B (defined as hypoxia or tachypnea) were randomly assigned to receive either 2 units (or pediatric equivalent) of anti-influenza plasma plus standard care (P+S), versus standard care alone (S), and were followed for 28 days. The primary endpoint was time to normalization of patients’ respiratory status (respiratory rate of ≤ 20 for adults or age defined thresholds of 20–38 for children), and a room air saturation of oxygen ≥ 93%. ClinicalTrials.gov Identifier: NCT01052480 Findings Between January 13, 2011 and March 2, 2015, 113 participants were screened, and 98 were randomized. Of the participants with confirmed influenza, 28 of 42 (67%) of P+S participants normalized their respiratory status by Day 28, as compared to 24 of 45 (53%) of S participants (p=0·069). The estimated hazard ratio comparing P+S to S was 1·71 (95% CI: 0·96 to 3·06). Six participants died, 1 (2%) and 5 (10%) from the P+S and S arms respectively (p=0·093). P+S participants had non-significant reductions in days in hospital (median 6 vs. 11 days, p=0·13) and days on mechanical ventilation (median 0 vs. 3 days, p=0·14), and significantly improved clinical status at Day 7 (p=0·020). Fewer P+S participants experienced SAEs compared to S recipients (20% vs. 38%, p= 0·041), the most frequent of which were acute respiratory distress syndrome (1 [2%] vs 2 [4%]) and stroke (1 [2%] vs 2 [4%]). Interpretation Results from this Phase II randomized trial of immune plasma for the treatment of severe influenza provides support for a possible benefit of immunotherapy across the primary and secondary endpoints. A Phase III randomized trial is now underway to further evaluate this intervention. PMID:28522352

Unique surface adsorption behaviors of serum proteins on chemically uniform and alternating surfaces

NASA Astrophysics Data System (ADS)

Song, Sheng

With increasing interests of studying proteins adsorption on the surfaces with nanoscale features in biomedical field, it is crucial to have fundamental understandings on how the proteins are adsorbed on such a surface and what factors contribute to the driving forces of adsorption. Besides, exploring more available nanoscale templates would greatly offer more possibilities one could design surface bio-detection methods with favorable protein-surface interactions. Thus, to fulfill the purpose, the work in this dissertation has been made into three major sections. First, to probe the intermediate states which possibly exist between stable and unstable phases described in mean-field theory diagram, a solvent vapor annealing method is chosen to slowly induce the copolymer polystyrene-block-polyvinylpyridine (PS-b-PVP)'s both blocks undergoing micro-phase separations from initial spherical nanodomains into terminal cylindrical nanodomains. During this process, real time atomic force microscopy (AFM) has been conducted to capture other six intermediate states with different morphologies on the polymeric film surfaces. Secondly, upon recognizing each intermediate state, the solution of immunoglobulin gamma (IgG) proteins has been deposited on the surface and been rinsed off with buffer solution before the protein-bounded surface is imaged by AFM. It has been found IgG showing a strong adsorption preference on PS over P4VP block. Among all the six intermediate states, the proteins are almost exclusively adsorbed on PS nanodomains regardless the concentration and deposition time. Thirdly, a trinodular shape protein fibrinogen (Fg) is selected for investigating how geometry and surface charge of proteins would interplay with cylindrical nanodomains on a surface developed from Polystyrene -block-Poly-(methyl methacrylate) PS-b-PMMA. Also, Fg adsorptions on chemically homogeneous surfaces are included here to have a better contrast of showing how much difference it can make by using it on a nanoscale surface. Interestingly, higher concentration of protein solution promotes the occurrences of single phase packed Fg on the PS domain. The densely packed network has formed where each Fg keeps its main body in PS domain and leaves its two alpha C chains on nearby PMMA domain. We believe this conformation and orientation would maximize both the hydrophobic and electrostatic interactions between Fg and the underlying surface.

Hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering temperature and concentration measurements using two different picosecond-duration probes.

PubMed

Kearney, Sean P; Scoglietti, Daniel J; Kliewer, Christopher J

2013-05-20

A hybrid fs/ps pure-rotational CARS scheme is characterized in furnace-heated air at temperatures from 290 to 800 K. Impulsive femtosecond excitation is used to prepare a rotational Raman coherence that is probed with a ps-duration beam generated from an initially broadband fs pulse that is bandwidth limited using air-spaced Fabry-Perot etalons. CARS spectra are generated using 1.5- and 7.0-ps duration probe beams with corresponding coarse and narrow spectral widths. The spectra are fitted using a simple phenomenological model for both shot-averaged and single-shot measurements of temperature and oxygen mole fraction. Our single-shot temperature measurements exhibit high levels of precision and accuracy when the spectrally coarse 1.5-ps probe beam is used, demonstrating that high spectral resolution is not required for thermometry. An initial assessment of concentration measurements in air is also provided, with best results obtained using the higher resolution 7.0-ps probe. This systematic assessment of the hybrid CARS technique demonstrates its utility for practical application in low-temperature gas-phase systems.

Free fatty acid particles in protein formulations, part 2: contribution of polysorbate raw material.

PubMed

Siska, Christine C; Pierini, Christopher J; Lau, Hollis R; Latypov, Ramil F; Fesinmeyer, R Matthew; Litowski, Jennifer R

2015-02-01

Polysorbate 20 (PS20) is a nonionic surfactant frequently used to stabilize protein biopharmaceuticals. During the development of mAb formulations containing PS20, small clouds of particles were observed in solutions stored in vials. The degree of particle formation was dependent on PS20 concentration. The particles were characterized by reversed-phase HPLC after dissolution and labeling with the fluorescent dye 1-pyrenyldiazomethane. The analysis showed that the particles consisted of free fatty acids (FFAs), with the distribution of types consistent with those found in the PS20 raw material. Protein solutions formulated with polysorbate 80, a chemically similar nonionic surfactant, showed a substantial delay in particle formation over time compared with PS20. Multiple lots of polysorbates were evaluated for FFA levels, each exhibiting differences based on polysorbate type and lot. Polysorbates purchased in more recent years show a greater distribution and quantity of FFA and also a greater propensity to form particles. This work shows that the quality control of polysorbate raw materials could play an important role in biopharmaceutical product quality. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Multi-megawatt inverter/converter technology for space power applications

NASA Technical Reports Server (NTRS)

Myers, Ira T.; Baumann, Eric D.; Kraus, Robert; Hammoud, Ahmad N.

1992-01-01

Large power conditioning mass reductions will be required to enable megawatt power systems envisioned by the Strategic Defense Initiative, the Air Force, and NASA. Phase 1 of a proposed two phase interagency program has been completed to develop an 0.1 kg/kW DC/DC converter technology base for these future space applications. Three contractors, Hughes, General Electric (GE), and Maxwell were Phase 1 contractors in a competitive program to develop a megawatt lightweight DC/DC converter. Researchers at NASA Lewis Research Center and the University of Wisconsin also investigated technology in topology and control. All three contractors, as well as the University of Wisconsin, concluded at the end of the Phase 1 study, which included some critical laboratory work, that 0.1-kg/kW megawatt DC/DC converters can be built. This is an order of magnitude lower specific weight than is presently available. A brief description of each of the concepts used to meet the ambitious goals of this program are presented.

Intense picosecond pulsed electric fields inhibit proliferation and induce apoptosis of HeLa cells.

PubMed

Zhang, Min; Xiong, Zheng-Ai; Chen, Wen-Juan; Yao, Cheng-Guo; Zhao, Zhong-Yong; Hua, Yuan-Yuan

2013-06-01

A picosecond pulsed electric field (psPEF) is a localized physical therapy for tumors that has been developed in recent years, and that may in the future be utilized as a targeted non‑invasive treatment. However, there are limited studies regarding the biological effects of psPEF on cells. Electric field amplitude and pulse number are the main parameters of psPEF that influence its biological effects. In this study, we exposed HeLa cells to a psPEF with a variety of electric field amplitudes, from 100 to 600 kV/cm, and various pulse numbers, from 1,000 to 3,000. An MTT assay was used to detect the growth inhibition, while flow cytometry was used to determine the occurrence of apoptosis and the cell cycle of the HeLa cells following treatment. The morphological changes during cell apoptosis were observed using transmission electron microscopy (TEM). The results demonstrated that the cell growth inhibition rate gradually increased, in correlation with the increasing electric field amplitude and pulse number, and achieved a plateau of maximum cell inhibition 12 h following the pulses. In addition, typical characteristics of HeLa cell apoptosis in the experimental groups were observed by TEM. The results demonstrated that the rate of apoptosis in the experimental groups was significantly elevated in comparison with the untreated group. In the treatment groups, the rate of apoptosis was greater in the higher amplitude groups than in the lower amplitude groups. The same results were obtained when the variable was the pulse number. Flow cytometric analysis indicated that the cell cycle of the HeLa cells was arrested at the G2/M phase following psPEF treatment. Overall, our results indicated that psPEF inhibited cell proliferation and induced cell apoptosis, and that these effects occurred in a dose-dependent manner. In addition, the results demonstrated that the growth of the HeLa cells was arrested at the G2/M phase following treatment. This study may provide a foundation for further in vivo experiments, and for the potential clinical application of psPEF in the treatment of cervical cancer.

Thioredoxin (Trxo1) interacts with proliferating cell nuclear antigen (PCNA) and its overexpression affects the growth of tobacco cell culture.

PubMed

Calderón, Aingeru; Ortiz-Espín, Ana; Iglesias-Fernández, Raquel; Carbonero, Pilar; Pallardó, Federico Vicente; Sevilla, Francisca; Jiménez, Ana

2017-04-01

Thioredoxins (Trxs), key components of cellular redox regulation, act by controlling the redox status of many target proteins, and have been shown to play an essential role in cell survival and growth. The presence of a Trx system in the nucleus has received little attention in plants, and the nuclear targets of plant Trxs have not been conclusively identified. Thus, very little is known about the function of Trxs in this cellular compartment. Previously, we studied the intracellular localization of PsTrxo1 and confirmed its presence in mitochondria and, interestingly, in the nucleus under standard growth conditions. In investigating the nuclear function of PsTrxo1 we identified proliferating cellular nuclear antigen (PCNA) as a PsTrxo1 target by means of affinity chromatography techniques using purified nuclei from pea leaves. Such protein-protein interaction was corroborated by dot-blot and bimolecular fluorescence complementation (BiFC) assays, which showed that both proteins interact in the nucleus. Moreover, PsTrxo1 showed disulfide reductase activity on previously oxidized recombinant PCNA protein. In parallel, we studied the effects of PsTrxo1 overexpression on Tobacco Bright Yellow-2 (TBY-2) cell cultures. Microscopy and flow-cytometry analysis showed that PsTrxo1 overexpression increases the rate of cell proliferation in the transformed lines, with a higher percentage of the S phase of the cell cycle at the beginning of the cell culture (days 1 and 3) and at the G2/M phase after longer times of culture (day 9), coinciding with an upregulation of PCNA protein. Furthermore, in PsTrxo1 overexpressed cells there is a decrease in the total cellular glutathione content but maintained nuclear GSH accumulation, especially at the end of the culture, which is accompanied by a higher mitotic index, unlike non-overexpressing cells. These results suggest that Trxo1 is involved in the cell cycle progression of TBY-2 cultures, possibly through its link with cellular PCNA and glutathione. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Ion transport mechanisms in lamellar phases of salt-doped PS-PEO block copolymer electrolytes.

PubMed

Sethuraman, Vaidyanathan; Mogurampelly, Santosh; Ganesan, Venkat

2017-11-01

We use a multiscale simulation strategy to elucidate, at an atomistic level, the mechanisms underlying ion transport in the lamellar phase of polystyrene-polyethylene oxide (PS-PEO) block copolymer (BCP) electrolytes doped with LiPF 6 salts. Explicitly, we compare the results obtained for ion transport in the microphase separated block copolymer melts to those for salt-doped PEO homopolymer melts. In addition, we also present results for dynamics of the ions individually in the PEO and PS domains of the BCP melt, and locally as a function of the distance from the lamellar interfaces. When compared to the PEO homopolymer melt, ions were found to exhibit slower dynamics in both the block copolymer (overall) and in the PEO phase of the BCP melt. Such results are shown to arise from the effects of slower polymer segmental dynamics in the BCP melt and the coordination characteristics of the ions. Polymer backbone-ion residence times analyzed as a function of distance from the interface indicate that ions have a larger residence time near the interface compared to that near the bulk of lamella, and demonstrates the influence of the glassy PS blocks and microphase segregation on the ion transport properties. Ion transport mechanisms in BCP melts reveal that there exist five distinct mechanisms for ion transport along the backbone of the chain and exhibit qualitative differences from the behavior in homopolymer melts. We also present results as a function of salt concentration which show that the mean-squared displacements of the ions decrease with increasing salt concentration, and that the ion residence times near the polymer backbone increase with increasing salt concentration.

Neisseria meningitidis Group A IgG1 and IgG2 Subclass Immune Response in African Children Aged 12–23 Months Following Meningococcal Vaccination

PubMed Central

Holme, Daniel; Findlow, Helen; Sow, Samba O.; Idoko, Olubukola T.; Preziosi, Marie-Pierre; Carlone, George; Plikaytis, Brian D.; Borrow, Ray

2015-01-01

Background. A group A meningococcal conjugate vaccine, PsA-TT, was licensed in 2010 and was previously studied in a phase 2 clinical trial to evaluate its safety and immunogenicity in African children 12–23 months of age. Methods. Subjects received either PsA-TT; meningococcal group A, C, W, Y polysaccharide vaccine (PsACWY); or Haemophilus influenzae type b conjugate vaccine (Hib-TT). Forty weeks following primary vaccination, the 3 groups were further randomized to receive either PsA-TT, one-fifth dose of PsACWY, or Hib-TT. Group A–specific immunoglobulin G (IgG) subclass response was characterized using an enzyme-linked immunosorbent assay. Results. The predominant IgG subclass response, regardless of vaccine, was IgG1. One month following primary vaccination, the geometric mean concentrations (GMCs) of IgG1 and IgG2 in the PsA-TT group were 21.73 µg/mL and 6.27 µg/mL, whereas in the PsACWY group the mean GMCs were 2.01 µg/mL and 0.97 µg/mL, respectively (P < .0001). Group A–specific IgG1 and IgG2 GMCs remained greater in the PsA-TT group than in the PsACWY group 40 weeks following primary vaccination (P < .0001). One week following revaccination, those given 2 doses of PsA-TT had the greatest IgG1 and IgG2 GMCs of 125.23 µg/mL and 36.12 µg/mL, respectively (P = .0008), and demonstrated a significant increase in IgG1:IgG2 mean ratio, indicative of the T-cell–dependent response associated with conjugate vaccines. Conclusions. Vaccination of African children aged 12–24 months with either PsA-TT or PsACWY elicited a predominantly IgG1 response. The IgG1:IgG2 mean ratio decreased following successive vaccination with PsACWY, indicating a shift toward IgG2, suggestive of the T-cell–independent immune response commonly associated with polysaccharide antigens. Clinical Trials Registration. SRCTN78147026. PMID:26553689

The characterization and application of a low resource FPGA-based time to digital converter

NASA Astrophysics Data System (ADS)

Balla, Alessandro; Mario Beretta, Matteo; Ciambrone, Paolo; Gatta, Maurizio; Gonnella, Francesco; Iafolla, Lorenzo; Mascolo, Matteo; Messi, Roberto; Moricciani, Dario; Riondino, Domenico

2014-03-01

Time to Digital Converters (TDCs) are very common devices in particles physics experiments. A lot of "off-the-shelf" TDCs can be employed but the necessity of a custom DAta acQuisition (DAQ) system makes the TDCs implemented on the Field-Programmable Gate Arrays (FPGAs) desirable. Most of the architectures developed so far are based on the tapped delay lines with precision down to 10 ps, obtained with high FPGA resources usage and non-linearity issues to be managed. Often such precision is not necessary; in this case TDC architectures with low resources occupancy are preferable allowing the implementation of data processing systems and of other utilities on the same device. In order to reconstruct γγ physics events tagged with High Energy Tagger (HET) in the KLOE-2 (K LOng Experiment 2), we need to measure the Time Of Flight (TOF) of the electrons and positrons from the KLOE-2 Interaction Point (IP) to our tagging stations (11 m apart). The required resolution must be better than the bunch spacing (2.7 ns). We have developed and implemented on a Xilinx Virtex-5 FPGA a 32 channel TDC with a precision of 255 ps and low non-linearity effects along with an embedded data acquisition system and the interface to the online FARM of KLOE-2. The TDC is based on a low resources occupancy technique: the 4×Oversampling technique which, in this work, is pushed to its best resolution and its performances were exhaustively measured.

An actively mode-locked fiber laser for sampling in a wide-bandwidth opto-electronic analog-to-digital converter

NASA Astrophysics Data System (ADS)

Powers, John P.; Pace, Phillip E.

2008-02-01

We have designed, built and tested an actively mode-locked fiber laser, operating at 1550 nm, for use as the sampling waveform in an opto-electronic analog-to-digital converter (ADC). Analysis shows that, in order to digitize a 10-GHz signal to 10 bits of resolution, the sampling pulsewidth must be less than 2.44 ps, the RMS timing jitter must be below 31.0 fs, and the RMS amplitude jitter must be below 0.195%. Fiber lasers have proven to have the capability to narrowly exceed these operating requirements. The fiber laser is a "sigma" laser consisting of Er-doped gain medium, dispersion-compensating fiber, nonlinear fiber, a Faraday rotation mirror, polarization-maintaining fiber and components, and diode pump lasers. The active mode-locking is achieved by a Mach-Zehnder interferometer modulator, driven by a frequency synthesizer operating at the desired sampling rate. A piezo-electric element is used in a feedback control loop to stabilize the output PRF against environmental changes. Measurements of the laser output revealed the maximum nominal PRF to be 16 GHz, the nominal pulsewidth to be 7.2 ps, and the nominal RNS timing jitter to be 386 fs. Incorporating this laser into a sampling ADC would allow us to sample a 805-MHz bandwidth signal to a resolution of 10 bits as limited by timing jitter. Techniques to reduce the timing-jitter bottleneck are discussed.

Quality-of-life and performance status results from the phase III RAINBOW study of ramucirumab plus paclitaxel versus placebo plus paclitaxel in patients with previously treated gastric or gastroesophageal junction adenocarcinoma.

PubMed

Al-Batran, S-E; Van Cutsem, E; Oh, S C; Bodoky, G; Shimada, Y; Hironaka, S; Sugimoto, N; Lipatov, O N; Kim, T-Y; Cunningham, D; Rougier, P; Muro, K; Liepa, A M; Chandrawansa, K; Emig, M; Ohtsu, A; Wilke, H

2016-04-01

The phase III RAINBOW trial demonstrated that the addition of ramucirumab to paclitaxel improved overall survival, progression-free survival, and tumor response rate in fluoropyrimidine-platinum previously treated patients with advanced gastric/gastroesophageal junction (GEJ) adenocarcinoma. Here, we present results from quality-of-life (QoL) and performance status (PS) analyses. Patients with Eastern Cooperative Oncology Group PS of 0/1 were randomized to receive ramucirumab (8 mg/kg i.v.) or placebo on days 1 and 15 of a 4-week cycle, with both arms receiving paclitaxel (80 mg/m(2)) on days 1, 8, and 15. Patient-reported outcomes were assessed with the QoL/health status questionnaires EORTC QLQ-C30 and EQ-5D at baseline and 6-week intervals. PS was assessed at baseline and day 1 of every cycle. Time to deterioration (TtD) in each QLQ-C30 scale was defined as randomization to first worsening of ≥10 points (on 100-point scale) and TtD in PS was defined as first worsening to ≥2. Hazard ratios (HRs) for treatment effect were estimated using stratified Cox proportional hazards models. Of the 665 patients randomized, 650 (98%) provided baseline QLQ-C30 and EQ-5D data, and 560 (84%) also provided data from ≥1 postbaseline time point. Baseline scores for both instruments were similar between arms. Of the 15 QLQ-C30 scales, 14 had HR < 1, indicating similar or longer TtD in QoL for ramucirumab + paclitaxel. Treatment with ramucirumab + paclitaxel was also associated with a delay in TtD in PS to ≥2 (HR = 0.798, P = 0.0941). Alternate definitions of PS deterioration yielded similar results: PS ≥ 3 (HR = 0.656, P = 0.0508), deterioration by ≥1 PS level (HR = 0.802, P = 0.0444), and deterioration by ≥2 PS levels (HR = 0.608, P = 0.0063). EQ-5D scores were comparable between treatment arms, stable during treatment, and worsened at discontinuation. In patients with previously treated advanced gastric/GEJ adenocarcinoma, addition of ramucirumab to paclitaxel prolonged overall survival while maintaining patient QoL with delayed symptom worsening and functional status deterioration. NCT01170663. © The Author 2016. Published by Oxford University Press on behalf of the European Society for Medical Oncology.

Variation of Ionic Conductivity with Annealing Temperature in Argyrodite Solid Electrolytes

NASA Astrophysics Data System (ADS)

Rao, R. Prasada; Chen, Maohua; Adams, Stefan

2013-07-01

In situ neutron diffraction studies of argyrodite-type Li6PS5X (X = Cl, Br, I) were conducted for mechanically milled sample to reveal the formation and growth of crystalline phases. These studies indicated the formation of crystals in all the compounds started from as low as 80°C. The Rietveld refinements of the resulting crystalline phases at 150°C indicate the formation of the argyrodite structure. Structure refinements using high-intensity neutron diffraction provide insight into the influence of disorder on the fast ionic conductivity. Besides the disorder in the lithium distribution, it is the disorder in the S2-/Cl- or S2-/Br- distribution that we find to promote ion mobility. Among the samples studied Li6PS5Br, annealed at 250°C, exhibited the highest ionic conductivity, 1.05 × 10-3 S/cm at room temperature. An all solid state battery with Li4Ti5O12/Li6PS5Br/Li exhibited 57 mAh/g first discharge capacity at 75°C with 91% coulombic efficiency after 60 cycles.

Laser processing of sapphire with picosecond and sub-picosecond pulses

NASA Astrophysics Data System (ADS)

Ashkenasi, D.; Rosenfeld, A.; Varel, H.; Wähmer, M.; Campbell, E. E. B.

1997-11-01

Laser processing of sapphire using a Ti:sapphire laser at 790 and 395 nm and pulse widths varying between 0.2 and 5 ps is reported. A clear improvement in quality is demonstrated for multi-shot processing with sub-ps laser pulses. For fluences between 3 and 12 J/cm 2 two ablation phases were observed, in agreement with previous work from Tam et al. using 30 ps, 266 nm laser pulses [A.C. Tam, J.L. Brand, D.C. Cheng, W. Zapka, Appl. Phys. Lett. 55 (20) (1994) 2045]. During the `gentle ablation' phase periodic wavelike structures, i.e. ripples, were observed on the Al 2O 3 surface, perpendicular to the laser polarisation and with a spacing almost equalling the laser wavelength, indicating metallic-like behaviour. The ripple modulation depth was in the order of a few tens of nm. For fluences between 1 and 2.5 J/cm 2, below the single-shot surface damage threshold and at a pulse width above 200 fs, microstructures could be produced at the rear side of a 1 mm thick sapphire substrate without affecting the front surface.

TDC-based readout electronics for real-time acquisition of high resolution PET bio-images

NASA Astrophysics Data System (ADS)

Marino, N.; Saponara, S.; Ambrosi, G.; Baronti, F.; Bisogni, M. G.; Cerello, P.,; Ciciriello, F.; Corsi, F.; Fanucci, L.; Ionica, M.; Licciulli, F.; Marzocca, C.; Morrocchi, M.; Pennazio, F.; Roncella, R.; Santoni, C.; Wheadon, R.; Del Guerra, A.

2013-02-01

Positron emission tomography (PET) is a clinical and research tool for in vivo metabolic imaging. The demand for better image quality entails continuous research to improve PET instrumentation. In clinical applications, PET image quality benefits from the time of flight (TOF) feature. Indeed, by measuring the photons arrival time on the detectors with a resolution less than 100 ps, the annihilation point can be estimated with centimeter resolution. This leads to better noise level, contrast and clarity of detail in the images either using analytical or iterative reconstruction algorithms. This work discusses a silicon photomultiplier (SiPM)-based magnetic-field compatible TOF-PET module with depth of interaction (DOI) correction. The detector features a 3D architecture with two tiles of SiPMs coupled to a single LYSO scintillator on both its faces. The real-time front-end electronics is based on a current-mode ASIC where a low input impedance, fast current buffer allows achieving the required time resolution. A pipelined time to digital converter (TDC) measures and digitizes the arrival time and the energy of the events with a timestamp of 100 ps and 400 ps, respectively. An FPGA clusters the data and evaluates the DOI, with a simulated z resolution of the PET image of 1.4 mm FWHM.

[Palliative sedation in a university hospital: experience after introducing a specific protocol].

PubMed

Boceta Osuna, J; Nabal Vicuña, M; Martínez Peñalver, F; Blanco Picabia, A; Aguayo Canela, M; Royo Aguado, J L

2013-01-01

A descriptive prospective study of palliative sedation (PS) records during a one year period after starting the PS protocol. Patients included in the PS protocol and those who had completed the "data registry form". Registry forms included in the PS protocol as Annex 5 (included as Annex 1 in this study). Personal data, data regarding basal disease, prognosis, level of information. Refractory symptoms: type, time of evolution and treatments employed. Involvement of the patient and/or representatives in decision making. Type of sedation, continuity, depth, employed, duration and results, and readjustment of other therapeutic measures. The SPSS 14.0 was used. For qualitative variables we studied absolute frequencies and proportions. For quantitative variables with normal distribution, we used means and standard deviations, and for non-normal distribution, medians and ranges. In the study period 90 cases of PS were counted. This represented 27.6% of the patients treated in the hospital palliative care support team (PCST), and 7.03% of the total deceased patients in our hospital. Mean age of patients undergoing PS was 59.22 years old, range between 40.86 and 77.58 years, and 68.1% were men. All patients were in an advanced or terminal stage of their condition, and 49.5% in an agonal phase. In 90.4% of the cases, the main pathology was oncological. Regarding PS indication, this was jointly made between the PCST physician and the patient's usual doctor in 60 cases (66.6%). Symptoms leading to sedation were mainly dyspnea, delirium and pain. The Ethics committee was consulted in five cases. Mean time under sedation was 134.02 hours (5.5 days). In 90% of the cases, duration ranged from 50 to 218.04 hours (2-9 days). Depth of PS after induction was registered in 88.8% of the cases. Informed consent (IC) was explicit in 11.2% of the cases,and given prior to the appearance of refractory symptoms and/or agonal phase. In 88.8% of sedation cases, the IC was given by a representative. Midazolam was the most used drug of choice in 87.8% of the cases, and levomepromazine in 10.2%. Up to 15% of sedations required drug changes or combinations. 1) The application of a PS Protocol and the availability of a hospital PCST and an Ethical Care Committee favored a safe (correct) use of PS in a hospital lacking a palliative care unit (PCU), and a homogeneous data registry for their analysis, with quality criteria similar to those offered by a PCU. 2) We have detected areas of improvement that will be applied in the second version of our protocol. Copyright © 2012 SECA. Published by Elsevier Espana. All rights reserved.

Interactions between polystyrene microplastics and marine phytoplankton lead to species-specific hetero-aggregation.

PubMed

Long, Marc; Paul-Pont, Ika; Hégaret, Hélène; Moriceau, Brivaela; Lambert, Christophe; Huvet, Arnaud; Soudant, Philippe

2017-09-01

To understand the fate and impacts of microplastics (MP) in the marine ecosystems, it is essential to investigate their interactions with phytoplankton as these may affect MP bioavailability to marine organisms as well as their fate in the water column. However, the behaviour of MP with marine phytoplanktonic cells remains little studied and thus unpredictable. The present study assessed the potential for phytoplankton cells to form hetero-aggregates with small micro-polystyrene (micro-PS) particles depending on microalgal species and physiological status. A prymnesiophycea, Tisochrysis lutea, a dinoflagellate, Heterocapsa triquetra, and a diatom, Chaetoceros neogracile, were exposed to micro-PS (2 μm diameter; 3.96 μg L -1 ) during their growth culture cycles. Micro-PS were quantified using an innovative flow-cytometry approach, which allowed the monitoring of the micro-PS repartition in microalgal cultures and the distinction between free suspended micro-PS and hetero-aggregates of micro-PS and microalgae. Hetero-aggregation was observed for C. neogracile during the stationary growth phase. The highest levels of micro-PS were "lost" from solution, sticking to flasks, with T. lutea and H. triquetra cultures. This loss of micro-PS sticking to the flask walls increased with the age of the culture for both species. No effects of micro-PS were observed on microalgal physiology in terms of growth and chlorophyll fluorescence. Overall, these results highlight the potential for single phytoplankton cells and residual organic matter to interact with microplastics, and thus potentially influence their distribution and bioavailability in experimental systems and the water column. Copyright © 2017 Elsevier Ltd. All rights reserved.

Efficacy and Safety of Ixekizumab in a Randomized, Double-Blinded, Placebo-Controlled Phase 3b Study of Patients with Moderate-to-Severe Genital Psoriasis.

PubMed

Ryan, C; Menter, A; Guenther, L; Blauvelt, A; Bissonnette, R; Meeuwis, K; Sullivan, J; Cather, J C; Yosipovitch, G; Gottlieb, A B; Merola, J F; Callis Duffin, K; Fretzin, S; Osuntokun, O O; Burge, R; Naegeli, A N; Yang, F E; Lin, C-Y; Todd, K; Potts Bleakman, A

2018-05-10

Genital psoriasis (GenPs) is a common, debilitating, and difficult to treat manifestation of plaque psoriasis. However, few controlled, interventional studies of GenPs exist. To determine the efficacy of ixekizumab versus placebo in patients with moderate-to-severe GenPs with BSA≥1%. Subjects with moderate-to-severe GenPs (defined as a baseline static Physician's Global Assessment of Genitalia [sPGA-G] score of ≥3) with BSA≥1% were randomized 1:1 to receive placebo (N=74) or the recommended dosing of ixekizumab (N=75). Major outcomes included the percentage of patients achieving 0 or 1 scores on the sPGA-G (primary endpoint), overall sPGA, GenPs Sexual Frequency Questionnaire (GenPs-SFQ) item 2, and a ≥3-point improvement from baseline on the GenPs itch numeric rating scale. At week 12, ixekizumab was superior to placebo on the sPGA-G 0/1 (73.3% versus 8.1%, p<0.001), overall sPGA 0/1 (73.3% versus 2.7%, p<0.001), GenPs-SFQ item 2 0/1 (78.4% versus 21.4%, p<0.001), and genital itch (59.7% versus 8.3%, p<0.001). No candidiasis was reported, no deaths occurred, and one (1.4%) serious adverse event was reported in a patient receiving placebo. Ixekizumab was superior to placebo for the treatment of moderate-to-severe GenPs with BSA≥1%. The safety profile of ixekizumab was consistent with previous studies in moderate-to-severe plaque psoriasis. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Photoswitching of ferroelectric liquid crystals using chiral thioindigo dopants: The development of a photochemical switch hitter.

PubMed

Lemieux, Robert P

2004-01-01

By virtue of its spontaneous polarization (PS), a ferroelectric SmC* liquid crystal can be switched between two states corresponding to opposite molecular tilt orientations using an electric field, thus producing an ON-OFF light shutter between crossed polarizers. Considerable efforts have been made over the past decade to develop photonic FLC light shutters because of their potential uses in dynamic holography and optical data storage. The ON-OFF switching of a FLC light shutter can be triggered by light via a photoinversion of PS using a photochromic dopant. The spontaneous polarization is a chiral bulk property that can be left-handed (negative) or right-handed (positive), depending on the absolute configuration of the chiral component of the SmC* phase. In the approach described herein, the magnitude of PS is modulated via the photoisomerization of a chiral thioindigo dopant that undergoes a large increase in transverse dipole moment upon trans-cis photoisomerization. The sign of PS is photoinverted using an "ambidextrous" thioindigo dopant containing a chiral 2-octyloxy side chain that is coupled to the thioindigo core and induces a positive PS, and a chiral 2,3-difluorooctyloxy side chain that is decoupled from the core and induces a negative PS. In the trans form, the 2,3-difluorooctyloxy side chain predominates and the net PS induced by the dopant is negative. However, upon trans-cis-photoisomerization, the increase in transverse dipole moment of the 2-octyloxy/thioindigo unit raises its induced PS over that of the decoupled 2,3-difluorooctyloxy side chain, and thus inverts the net sign of PS induced by the dopant from negative to positive. Copyright 2004 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Mid-infrared picosecond pump-dump-probe and pump-repump-probe experiments to resolve a ground-state intermediate in cyanobacterial phytochrome Cph1.

PubMed

van Wilderen, Luuk J G W; Clark, Ian P; Towrie, Michael; van Thor, Jasper J

2009-12-24

Multipulse picosecond mid-infrared spectroscopy has been used to study photochemical reactions of the cyanobacterial phytochrome photoreceptor Cph1. Different photophysical schemes have been discussed in the literature to describe the pathways after photoexcitation, particularly, to identify reaction phases that are linked to photoisomerisation and electronic decay in the 1566-1772 cm(-1) region that probes C=C and C=O stretching modes of the tetrapyrrole chromophore. Here, multipulse spectroscopy is employed, where, compared to conventional visible pump-mid-infrared probe spectroscopy, an additional visible pulse is incorporated that interacts with populations that are evolving on the excited- and ground-state potential energy surfaces. The time delays between the pump and the dump pulse are chosen such that the dump pulse interacts with different phases in the reaction process. The pump and dump pulses are at the same wavelength, 640 nm, and are resonant with the Pr ground state as well as with the excited state and intermediates. Because the dump pulse additionally pumps the remaining, partially recovered, and partially oriented ground-state population, theory is developed for estimating the fraction of excited-state molecules. The calculations take into account the model-dependent ground-state recovery fraction, the angular dependence of the population transfer resulting from the finite bleach that occurs with linearly polarized intense femtosecond optical excitation, and the partially oriented population for the dump field. Distinct differences between the results from the experiments that use a 1 or a 14 ps dump time favor a branching evolution from S1 to an excited state or reconfigured chromophore and to a newly identified ground-state intermediate (GSI). Optical dumping at 1 ps shows the instantaneous induced absorption of a delocalized C=C stretching mode at 1608 cm(-1), where the increased cross section is associated with the electronic ground-state structure of the ZZZ configuration of the linear tetrapyrrole chromophore. The dump-induced absorption decays with time constants of 5 and 19 ps to the Pr ground state. Employing a dump pulse at 14 ps results in an instantaneous decrease of the absorption of the 1608 cm(-1) band, indicating repumping of the GSI. The dump-induced absorption recovers back to the GSI with a 6 ps lifetime. A spectral similarity is observed between the 6 ps phase in the dump experiment and the 3 ps component found in the two-pulse pump-probe measurement. Combined with the dominance of ground-state absorption bands in the dump-induced spectrum, this indicates the presence of a GSI, which is additionally characterized by previously unidentified induced absorption at 1710 and 1570-80 cm(-1). The metastable photoproduct Lumi-R, which is in the electronic ground state and populated at 500 ps after excitation of Pr, is highly efficiently repumped into the Pr ground state with the power density used. After repumping, Lumi-R is not recovered on the 500 ps time scale of the experiment and is distinct from the GSI of Pr since it is not associated with its characteristic induced absorption at 1710 and 1570-80 cm(-1).

Molecules-to-Ecosphere View Emerges From Study of Student-Chosen Organisms

ERIC Educational Resources Information Center

Schmit, Palma J.

1973-01-01

Describes a high school biology program based on student investigations. The comparative study of different topics in plants and animals is stressed. First phase of the course centers around relationships between the ecosphere and the individual; the second phase considers the molecules and the individual. (PS)

Toward Strong Thermoplastic Elastomers with Asymmetric Miktoarm Block Copolymer Architectures

DTIC Science & Technology

2014-03-05

temperature [such as poly(phenylene oxide), PPO ].7,8 Yet, this method does not lift the volume fraction limitation, and the total hard phase fraction f...PS + f PPO must still remain below approximately 0.3. Being able to significantly displace the classical phase diagram and stabilize morphologies

Motivational enhancement therapy to improve treatment utilization and outcome in pregnant substance users

PubMed Central

Winhusen, Theresa; Kropp, Frankie; Babcock, Dean; Hague, Diane; Erickson, Sarah J.; Renz, Connie; Rau, Leela; Lewis, Daniel; Leimberger, Jeff; Somoza, Eugene

2008-01-01

Pregnant substance users can benefit significantly from substance abuse treatment but treatment retention can be challenging. Two hundred pregnant substance users entering outpatient substance abuse treatment at 1 of 4 treatment programs were randomized to receive either 3 individual sessions of Motivational Enhancement Therapy for pregnant substance users (MET-PS) or the first 3 individual sessions normally provided by the program. All participants were encouraged to participate in all other treatment offered by the program. Outcome measures included treatment utilization according to clinic records, qualitative urine toxicology measures, and self-report of substance use. One hundred and sixty two participants (i.e., 81%) completed the 1 month active phase. Participants attended 62% of scheduled treatment on average and reported decreased substance use during the first month of treatment, with no differences between MET-PS and treatment as usual participants. There was some evidence that the efficacy of MET-PS varied between sites and that MET-PS might be more beneficial than TAU in decreasing substance use in minority participants. These results suggest that MET-PS is not more effective than treatment as usual for pregnant substance users in general but that there might be particular subgroups or treatment programs for which MET-PS might be more or less effective than treatment as usual. PMID:18083322

Utilization of composite membrane polyethyleneglycol-polystyrene-cellulose acetate from pineapple leaf fibers in lowering levels of methyl orange batik waste

NASA Astrophysics Data System (ADS)

Delsy, E. V. Y.; Irmanto; Kazanah, F. N.

2017-02-01

Pineapple leaves are agricultural waste from the pineapple that the fibers can be utilized as raw material in cellulose acetate membranes. First, made pineapple leaf fibers into pulp and then converted into cellulose acetate by acetylation process in four stages consisting of activation, acetylation, hydrolysis and purification. Cellulose acetate then used as the raw material to manufacture composite membrane with addition of polystyrene and poly (ethylene glycol) as porogen. Composite membrane is made using phase inversion method with dichloromethane-acetone as a solvent. The result of FTIR analysis (Fourier transform infra-red) showed that the absorption of the carbonyl group (C=O) is at 1643.10 cm-1 and acetyl group (C-O ) at 1227.01 cm-1, with a molecular weight of 8.05 x 104 g/mol and the contents (rate) of acetyl is 37.31%. PS-PEG-CA composite membrane had also been characterized by measuring the water flux values and its application to decrease methyl orange content (level) in batik waste. The results showed that the water flux value is of 25.62 L/(m2.hour), and the decrease percentage of methyl orange content in batik waste is 71.53%.

Spatial-temporal patterns and driving mechanisms of semiannual variations in the Philippine Sea

NASA Astrophysics Data System (ADS)

Zhao, Jun; Li, Yuanlong; Wang, Fan; Zhai, Fangguo; Yu, Xiaolin

2012-10-01

Satellite altimetric sea surface height (SSH) measurements from 1992 through 2010 are used to explore the oceanic semiannual variations in the Philippine Sea (PS). Pronounced semiannual SSH variations are detected within two zonal bands. One lies east of Luzon Strait (19°-22°N) in the northern PS, while the other is southeast of Mindanao coast (4°-7°N) in the southern PS. In the two near-coast boxes where semiannual harmonic amplitude exceeds 4 cm, the northern box (127°-133°E, 19°-22°N) and the southern box (127°-133°E, 4°-7°N), semiannual changes contribute considerably to the total annual SSH variance by 12% and 17%, respectively. Despite prominent SSH variability, the bifurcation latitude of the North Equatorial Current (NBL) exhibits weak fluctuations with a peak-to-peak difference of only 0.3° on semiannual time scale. While the in-phase annual SSH variations between the two boxes work together to enhance annual NBL changes, their out-of-phase semiannual SSH variations offset each other in driving the NBL displacements. Further analysis with a 11/2-layer reduced-gravity model forced by ECMWF wind stress reveals that the observed semiannual SSH variations are primarily driven by local wind forcing in the far western Pacific. Rossby wave signals propagating from the eastern/central Pacific contribute much less due to along-path dispersion and cancellation. Semiannual signals of wind field in the northern PS reflect mainly the semiannual changes of the Asian Monsoon system, while those in the southern PS arise from the combined effects of Monsoon transition and the annual migration of the intertropical convergence zone (ITCZ).

Enhanced primary sludge sonication by heat insulation to reclaim carbon source for biological phosphorous removal.

PubMed

Tian, Qing; Wang, Qi; Zhu, Yanbing; Li, Fang; Zhuang, Lin; Yang, Bo

2017-01-01

Ultrasound pretreatment is a potent step to disintegrate primary sludge (PS). The supernatant of sonicated PS is recycled as an alternative carbon source for biological phosphorus removal. In this study, we investigated the role of temperature on PS disintegration during sonication. We found that a temperature of 60°C yielded a dissolution rate of about 2% soluble chemical oxygen demand (SCOD) as compared to 7% SCOD using sonication at the specific energy (SE) of 7359kJ/kg TS. Using the SE of 6000kJ/kg TS with heat insulation during sonication, the SCOD dissolution rate of PS was similar to the result at the SE of 7051kJ/kg TS without heat insulation. Upon treatment with sonication, the PS released low concentrations of Cu and Zn into the supernatant. The phosphorus-accumulating organisms (PAOs) used the supernatant of sonicated PS as the carbon source. Supplementation with the diluted sonicated PS supernatant (SCOD≈1000mg/L) in anaerobic phase resulted in the release of phosphorus (36mg/L) and the production of polyhydroxyalkanoates (PHAs) (0.36g PHA/g SS). Compared with sodium acetate, higher polyhydroxyvalerate (PHV) faction in the polyhydroxyalkanoates (PHAs) was observed in the biomass when incubated with sonicated PS as the carbon source. This work provides a simple pathway to conserve energy and to enhance efficiencies of ultrasonic pretreatment and the recovery of carbon source from the sludge for improving the phosphorus removal in the ENR system. Copyright © 2016 Elsevier B.V. All rights reserved.

Unveiling the Molecular Structure of Pulmonary Surfactant Corona on Nanoparticles.

PubMed

Hu, Qinglin; Bai, Xuan; Hu, Guoqing; Zuo, Yi Y

2017-07-25

The growing risk of human exposure to airborne nanoparticles (NPs) causes a general concern on the biosafety of nanotechnology. Inhaled NPs can deposit in the deep lung at which they interact with the pulmonary surfactant (PS). Despite the increasing study of nano-bio interactions, detailed molecular mechanisms by which inhaled NPs interact with the natural PS system remain unclear. Using coarse-grained molecular dynamics simulation, we studied the interaction between NPs and the PS system in the alveolar fluid. It was found that regardless of different physicochemical properties, upon contacting the PS, both silver and polystyrene NPs are immediately coated with a biomolecular corona that consists of both lipids and proteins. Structure and molecular conformation of the PS corona depend on the hydrophobicity of the pristine NPs. Quantitative analysis revealed that lipid composition of the corona formed on different NPs is relatively conserved and is similar to that of the bulk phase PS. However, relative abundance of the surfactant-associated proteins, SP-A, SP-B, and SP-C, is notably affected by the hydrophobicity of the NP. The PS corona provides the NPs with a physicochemical barrier against the environment, equalizes the hydrophobicity of the pristine NPs, and may enhance biorecognition of the NPs. These modifications in physicochemical properties may play a crucial role in affecting the biological identity of the NPs and hence alter their subsequent interactions with cells and other biological entities. Our results suggest that all studies of inhalation nanotoxicology or NP-based pulmonary drug delivery should consider the influence of the PS corona.

Aqueous-Based Fabrication of Low-VOC Nanostructured Block Copolymer Films as Potential Marine Antifouling Coatings.

PubMed

Kim, Kris S; Gunari, Nikhil; MacNeil, Drew; Finlay, John; Callow, Maureen; Callow, James; Walker, Gilbert C

2016-08-10

The ability to fabricate nanostructured films by exploiting the phenomenon of microphase separation has made block copolymers an invaluable tool for a wide array of coating applications. Standard approaches to engineering nanodomains commonly involve the application of organic solvents, either through dissolution or annealing protocols, resulting in the release of volatile organic compounds (VOCs). In this paper, an aqueous-based method of fabricating low-VOC nanostructured block copolymer films is presented. The reported procedure allows for the phase transfer of water insoluble triblock copolymer, poly(styrene-block-2 vinylpyridine-block-ethylene oxide) (PS-b-P2VP-b-PEO), from a water immiscible phase to an aqueous environment with the assistance of a diblock copolymeric phase transfer agent, poly(styrene-block-ethylene oxide) (PS-b-PEO). Phase transfer into the aqueous phase results in self-assembly of PS-b-P2VP-b-PEO into core-shell-corona micelles, which are characterized by dynamic light scattering techniques. The films that result from coating the micellar solution onto Si/SiO2 surfaces exhibit nanoscale features that disrupt the ability of a model foulant, a zoospore of Ulva linza, to settle. The multilayered architecture consists of a pH-responsive P2VP-"shell" which can be stimulated to control the size of these features. The ability of these nanostructured thin films to resist protein adsorption and serve as potential marine antifouling coatings is supported through atomic force microscopy (AFM) and analysis of the settlement of Ulva linza zoospore. Field trials of the surfaces in a natural environment show the inhibition of macrofoulants for 1 month.

A medical oncologist's approach to immunotherapy for advanced renal tumors: is nephrectomy indicated?

PubMed

Cooney, Matthew M; Remick, Scot C; Vogelzang, Nicholas J

2004-02-01

Metastatic renal cell carcinoma is highly resistant to systemic therapy. Although interleukin-2 and interferon remain the most active agents for this disease, long-term survival rates remain poor. Two phase 3 trials, European Organization Research and Treatment of Cancer 30947 and Southwest Oncology Group 8949, have demonstrated a survival benefit of nephrectomy followed by interferon versus interferon alone in patients having an excellent performance status (PS 0 and 1). Removal of the primary tumor followed by interferon is not recommended for patients with a moderate or poor PS (PS 2-4). Even with this aggressive approach, most patients eventually will die from their kidney cancer; therefore, every patient with metastatic disease should be considered for enrollment into clinical trials.

Application of fiber grating-based acoustic sensor in progressive failure testing of e-glass/vinylester curve composites

NASA Astrophysics Data System (ADS)

Azmi, Asrul Izam; Raju, Raju; Peng, Gang-Ding

2012-02-01

This paper reports an application of phase shifted fiber Bragg grating (PS-FBG) intensity-type acoustic sensor in a continuous and in-situ failure testing of an E-glass/vinylester top hat stiffener (THS). The narrow transmission channel of the PS-FBG is highly sensitive to small perturbation, hence suitable to be used in an effective acoustic emission (AE) assessment technique. The progressive failure of THS was tested under transverse loading to experimentally simulate the actual loading in practice. Our experimental tests have demonstrated, in good agreement with the commercial piezoelectric sensors, that the important failures information of the THS was successfully recorded by the simple intensity-type PS-FBG sensor.

Failure monitoring of E-glass/vinylester composites using fiber grating acoustic sensor

NASA Astrophysics Data System (ADS)

Azmi, A. I.; Raju; Peng, G. D.

2013-06-01

This paper reports an application of an optical fiber sensor in a continuous and in situ failure testing of an E-glass/vinylester top hat stiffener (THS). The sensor head was constructed from a compact phase-shifted fiber Bragg grating (PS-FBG). The narrow transmission channel of the PS-FBG is highly sensitive to small perturbation, hence suitable to be used in acoustic emission (AE) assessment technique. The progressive failure of THS was tested under transverse loading to experimentally simulate the actual loading in practice. Our experimental tests have demonstrated, in good agreement with the commercial piezoelectric sensors, that the important failures information of the THS was successfully recorded by the simple intensity-type PS-FBG sensor.

Heterogeneous to homogeneous melting transition visualized with ultrafast electron diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

The ultrafast laser excitation of matters leads to non-equilibrium states with complex solid-liquid phase transition dynamics. We used electron diffraction at mega-electronvolt energies to visualize the ultrafast melting of gold on the atomic scale length. For energy densities approaching the irreversible melting regime, we first observed heterogeneous melting on time scales of 100 ps to 1000 ps, transitioning to homogeneous melting that occurs catastrophically within 10-20 ps at higher energy densities. We showed evidence for the heterogeneous coexistence of solid and liquid. We determined the ion and electron temperature evolution and found superheated conditions. Our results constrain the electron-ion couplingmore » rate, determine the Debye temperature and reveal the melting sensitivity to nucleation seeds.« less

Determination of enthalpies of formation of energetic molecules with composite quantum chemical methods

DOE PAGES

Manaa, M. Riad; Fried, Laurence E.; Kuo, I-Feng W.

2016-02-01

We report gas-phase enthalpies of formation for the set of energetic molecules NTO, DADE, LLM-105, TNT, RDX, TATB, HMX, and PETN using the G2, G3, G4, and ccCA-PS3 quantum composite methods. Calculations for HMX and PETN hitherto represent the largest molecules attempted with these methods. G3 and G4 calculations are typically close to one another, with a larger difference found between these methods and ccCA-PS3. Furthermore there is significant uncertainty in experimental values, the mean absolute deviation between the average experimental value and calculations are 12, 6, 7, and 3 kcal/mol for G2, G3, G4, and ccCA-PS3, respectively.

Present status and future directions of the Mayo/IBM PACS project

NASA Astrophysics Data System (ADS)

Morin, Richard L.; Forbes, Glenn S.; Gehring, Dale G.; Salutz, James R.; Pavlicek, William

1991-07-01

This joint project began in 1988 and was motivated by the need to develop an alternative to the archival process in place at that time (magnetic tape) for magnetic resonance imaging and neurological computed tomography. In addition, this project was felt to be an important step in gaining the necessary clinical experience for the future implementation of various aspects of electronic imaging. The initial phase of the project was conceived and developed to prove the concept, test the fundamental components, and produce performance measurements for future work. The key functions of this phase centered on attachment of imaging equipment (GE Signa) and archival processes using a non-dedicated (institutionally supplied) local area network (LAN). Attachment of imaging equipment to the LAN was performed using commercially available devices (Ethernet, PS/2, Token Ring). Image data were converted to ACR/NEMA format with retention of the vendor specific header information. Performance measurements were encouraging and led to the design of following projects. The second phase has recently been concluded. The major features of this phase have been to greatly expand the network, put the network into clinical use, establish an efficient and useful viewing station, include diagnostic reports in the archive data, provide wide area network (WAN) capability via ISDN, and establish two-way real-time video between remote sites. This phase has heightened both departmental and institutional thought regarding various issues raised by electronic imaging. Much discussion regarding both present as well as future archival processes has occurred. The use of institutional LAN resources has proven to be adequate for the archival function examined thus far. Experiments to date have shown that use of dedicated resources will be necessary for retrieval activities at even a basic level. This report presents an overview of the background present status and future directions of the project.

Local convertibility of the ground state of the perturbed toric code

NASA Astrophysics Data System (ADS)

Santra, Siddhartha; Hamma, Alioscia; Cincio, Lukasz; Subasi, Yigit; Zanardi, Paolo; Amico, Luigi

2014-12-01

We present analytical and numerical studies of the behavior of the α -Renyi entropies in the toric code in presence of several types of perturbations aimed at studying the simulability of these perturbations to the parent Hamiltonian using local operations and classical communications (LOCC)—a property called local convertibility. In particular, the derivatives, with respect to the perturbation parameter, present different signs for different values of α within the topological phase. From the information-theoretic point of view, this means that such ground states cannot be continuously deformed within the topological phase by means of catalyst assisted local operations and classical communications (LOCC). Such LOCC differential convertibility is on the other hand always possible in the trivial disordered phase. The non-LOCC convertibility is remarkable because it can be computed on a system whose size is independent of correlation length. This method can therefore constitute an experimentally feasible witness of topological order.

A Facile Synthesis of Dynamic, Shape Changing Polymer Particles

PubMed Central

Klinger, Daniel; Wang, Cynthia; Connal, Luke A.; Audus, Debra J.; Jang, Se Gyu; Kraemer, Stephan; Killops, Kato L.; Fredrickson, Glenn H.; Kramer, Edward J.; Hawker, Craig J.

2014-01-01

We herein report a new facile strategy to ellipsoidal block copolymer nanoparticles exhibiting a pH-triggered anistropic swelling profile. In a first step, elongated particles with an axially stacked lamellae structure are selectively prepared by utilizing functional surfactants to control the phase separation of symmetric PS-b-P2VP in dispersed droplets. In a second step, the dynamic shape change is realized by crosslinking the P2VP domains, hereby connecting glassy PS discs with pH-sensitive hydrogel actuators. PMID:24700705

Low Noise Optically Pre-amplified Lightwave Receivers and Other Applications of Fiber Optic Parametric Amplifiers

DTIC Science & Technology

2010-07-27

provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently... PERSON A. GAVRIELIDES a. REPORT UNCLAS b. ABSTRACT UNCLAS c. THIS PAGE UNCLAS 19b. TELEPHONE NUMBER (Include area code) +44 (0)1895 616205...PS) FOPAs are discussed, and the phase-squeezing behavior of PS-FOPAs is characterized in Sec V. In Sec. VI, we present measurements of the noise

A high-resolution time-to-digital converter using a three-level resolution

NASA Astrophysics Data System (ADS)

Dehghani, Asma; Saneei, Mohsen; Mahani, Ali

2016-08-01

In this article, a three-level resolution Vernier delay line time-to-digital converter (TDC) was proposed. The proposed TDC core was based on the pseudo-differential digital architecture that made it insensitive to nMOS and pMOS transistor mismatches. It also employed a Vernier delay line (VDL) in conjunction with an asynchronous read-out circuitry. The time interval resolution was equal to the difference of delay between buffers of upper and lower chains. Then, via the extra chain included in the lower delay line, resolution was controlled and power consumption was reduced. This method led to high resolution and low power consumption. The measurement results of TDC showed a resolution of 4.5 ps, 12-bit output dynamic range, and integral nonlinearity of 1.5 least significant bits. This TDC achieved the consumption of 68.43 µW from 1.1-V supply.

Effects of heat induced by two-photon absorption and free-carrier absorption in silicon-on-insulator nanowaveguides operating as all-optical wavelength converters.

PubMed

Abdollahi, Siamak; Moravvej-Farshi, Mohammad Kazem

2009-05-01

We propose a new numerical model to analyze heat induced by two-photon absorption and free-carrier absorption, while high intensity optical pulses propagate along silicon-on-insulator (SOI) nanowaveguides (NWGs). Using this model, we demonstrate that such induced heat causes a shift in the amount of wavelength conversion and hence deteriorates the converter output characteristics for pulses in the picosecond regime. The wavelength shift induced by a pulse with maximum input intensity and full width at half-maximum of I(max)=1.5x10(10) W x cm(-2) and T(FWHM)=30 ps, propagating along a SOI NWG with an effective cross-sectional area of a(eff)=0.15 microm(2), is shown to be Delta lambda(s) approximately 8 pm. We also demonstrate that such a shift can be compensated by tuning the pump intensity down by approximately 6.33%.

Time-resolved optical spectrometer based on a monolithic array of high-precision TDCs and SPADs

NASA Astrophysics Data System (ADS)

Tamborini, Davide; Markovic, Bojan; Di Sieno, Laura; Contini, Davide; Bassi, Andrea; Tisa, Simone; Tosi, Alberto; Zappa, Franco

2013-12-01

We present a compact time-resolved spectrometer suitable for optical spectroscopy from 400 nm to 1 μm wavelengths. The detector consists of a monolithic array of 16 high-precision Time-to-Digital Converters (TDC) and Single-Photon Avalanche Diodes (SPAD). The instrument has 10 ps resolution and reaches 70 ps (FWHM) timing precision over a 160 ns full-scale range with a Differential Non-Linearity (DNL) better than 1.5 % LSB. The core of the spectrometer is the application-specific integrated chip composed of 16 pixels with 250 μm pitch, containing a 20 μm diameter SPAD and an independent TDC each, fabricated in a 0.35 μm CMOS technology. In front of this array a monochromator is used to focus different wavelengths into different pixels. The spectrometer has been used for fluorescence lifetime spectroscopy: 5 nm spectral resolution over an 80 nm bandwidth is achieved. Lifetime spectroscopy of Nile blue is demonstrated.

Investigating Advances in the Acquisition of Secure Systems Based on Open Architecture, Open Source Software, and Software Product Lines

DTIC Science & Technology

2012-01-27

example is found in games converted to serve a purpose other than entertainment , such as the development and use of games for science, technology, and...These play-session histories can then be further modded via video editing or remixing with other media (e.g., adding music ) to better enable cinematic...available OSS (e.g., the Linux Kernel on the Sony PS3 game console2) that game system hackers seek to undo. Finally, games are one of the most commonly

Intracellular dynamics of cationic and anionic polystyrene nanoparticles without direct interaction with mitotic spindle and chromosomes.

PubMed

Liu, Yuexian; Li, Wei; Lao, Fang; Liu, Ying; Wang, Liming; Bai, Ru; Zhao, Yuliang; Chen, Chunying

2011-11-01

The fate of nanomaterials with different sizes and charges in mitotic cells is of great importance but seldom explored. Herein we investigate the intracellular fate of negatively charged carboxylated polystyrene (COOH-PS) and positively charged amino-modified polystyrene (NH(2)-PS) nanoparticles of three different diameters (50, 100 and 500 nm) on cancer HeLa cells and normal NIH 3T3 cells during the cell cycles. The results showed that all the fluorescent PS nanoparticles differing in size and/or charge did not interact with chromosome reorganization and cytoskeleton assembly during the mitotic process in live cells. They neither disturbed chromosome reorganization nor affected the cytoskeleton reassembly in both normal and cancer cells. However, NH(2)-PS at the size of 50 nm caused G1 phase delay and a decrease of cyclin (D, E) expression, respectively. Moreover, NH(2)-PS displayed higher cellular toxicity and NH(2)-PS of 50 nm disturbed the integrity of cell membranes. Both cationic and anionic PS nanoparticles had a more pronounced effect on normal NIH 3T3 cells than cancer HeLa cell. Our research provides insight into the dynamic fate, intracellular behavior, and the effects of nanoparticles on spindle and chromosomes during cell division, which will enable the optimization of design and selection of much safer nanoparticles for lower risk to human health and widely medical applications. Copyright © 2011 Elsevier Ltd. All rights reserved.

Excited stilbene: intramolecular vibrational redistribution and solvation studied by femtosecond stimulated Raman spectroscopy.

PubMed

Weigel, A; Ernsting, N P

2010-06-17

Excited-state relaxation of cis- and trans-stilbene is traced with femtosecond stimulated Raman spectroscopy, exploiting S(n) <-- S(1) resonance conditions. For both isomers, decay in Raman intensity, shift of spectral positions, and broadening of the bands indicate intramolecular vibrational redistribution (IVR). In n-hexane this process effectively takes 0.5-0.7 ps. Analysis of the intensity decay allows us to further distinguish two phases for trans-stilbene: fast IVR within a subset of modes (approximately 0.3 ps) followed by slower equilibration over the full vibrational manifold (approximately 0.9 ps). In acetonitrile IVR completes with 0.15 ps; this acceleration may originate from symmetry breakage induced by the polar solvent. Another process, dynamic solvation by acetonitrile, is seen as spectral narrowing and characteristic band shifts of the C=C stretch and phenyl bending modes with 0.69 ps. Wavepacket motion is observed in both isomers as oscillation of low-frequency bands with their pertinent mode frequency (90 or 195 cm(-1) in trans-stilbene; 250 cm(-1) in cis-stilbene). Anharmonic coupling shows up as a modulation of high-frequency peak positions by phenyl/ethylene torsion modes of 57 and 90 cm(-1). Decay and shift of the 90 cm(-1) inverse Raman band within the first 0.3 ps suggests a gradual involvement of phenyl/ethylene torsion in relaxation. In cis- and trans-stilbene, low-frequency spectral changes are found within 0.15 ps, indicating an additional ultrafast process.

Cascaded Quadruple Active Bridge Structures for Multilevel DC to Three-Phase AC Conversion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Brian B; Achanta, Prasanta K; Maksimovic, Dragan

This paper introduces a multilevel architecture comprised of interconnected dc to three-phase ac converter units. To enable series connected operation, each converter unit contains a quadruple active bridge (QAB) converter that provides isolation between the dc side and each of the three ac sides. Since each converter unit transfers dc-side power as constant balanced three-phase power on the ac side, this implies instantaneous input-output power balance and allows elimination of bulk capacitive energy storage. In addition to minimizing required capacitance, the proposed approach simultaneously enables simplified dc-link controllers amenable to decentralized implementation, supports bidirectional power transfer, and exhibits a modularmore » structure to enhance scalability. Isolation provided by the QAB allows a wide range of electrical configurations among multiple units in various dc-ac, ac-dc or ac-ac applications. In this paper, the focus is on series connections on the ac side to emphasize multilevel operation, and the approach is experimentally validated in a dc-ac system containing two cascaded converter units.« less

Risk factors associated to diabetes in Mexican population and phenotype of the individuals who will convert to diabetes.

PubMed

González-Villalpando, Clicerio; Dávila-Cervantes, Claudio Alberto; Zamora-Macorra, Mireya; Trejo-Valdivia, Belem; González-Villalpando, María Elena

2014-01-01

To describe risk factors associated to the incidence of type 2 diabetes (T2D) in Mexican population and to define phenotypic (clinical, anthropometric, metabolic) characteristics present in the individual who will convert to diabetes, regardless of time of onset. The Mexico City Diabetes Study began in 1990, with 2 282 participants, and had three subsequent phases: 1994, 1998, and 2008. A systematic evaluation with an oral glucose tolerance test was performed in each phase. For diagnosis of T2D, American Diabetes Association criteria were used. The population at risk was 1939 individuals. Subjects who were in the converter stage (initially non diabetic that eventually converted to T2D) had, at baseline, higher BMI (30 vs 27), systolic blood pressure (119 vs 116 mmHg), fasting glucose (90 vs 82mg/dl), triglycerides (239 vs 196mg/dl), and cholesterol (192 vs 190mg/dl), compared with subjects who remained non converters (p<0.05). The phenotype described represents a potentially identifiable phase and a target for preventive intervention.

Entanglement convertibility by sweeping through the quantum phases of the alternating bonds XXZ chain

PubMed Central

Tzeng, Yu-Chin; Dai, Li; Chung, Ming-Chiang; Amico, Luigi; Kwek, Leong-Chuan

2016-01-01

We study the entanglement structure and the topological edge states of the ground state of the spin-1/2 XXZ model with bond alternation. We employ parity-density matrix renormalization group with periodic boundary conditions. The finite-size scaling of Rényi entropies S2 and S∞ are used to construct the phase diagram of the system. The phase diagram displays three possible phases: Haldane type (an example of symmetry protected topological ordered phases), Classical Dimer and Néel phases, the latter bounded by two continuous quantum phase transitions. The entanglement and non-locality in the ground state are studied and quantified by the entanglement convertibility. We found that, at small spatial scales, the ground state is not convertible within the topological Haldane dimer phase. The phenomenology we observe can be described in terms of correlations between edge states. We found that the entanglement spectrum also exhibits a distinctive response in the topological phase: the effective rank of the reduced density matrix displays a specifically large “susceptibility” in the topological phase. These findings support the idea that although the topological order in the ground state cannot be detected by local inspection, the ground state response at local scale can tell the topological phases apart from the non-topological phases. PMID:27216970

Entanglement convertibility by sweeping through the quantum phases of the alternating bonds XXZ chain.

PubMed

Tzeng, Yu-Chin; Dai, Li; Chung, Ming-Chiang; Amico, Luigi; Kwek, Leong-Chuan

2016-05-24

We study the entanglement structure and the topological edge states of the ground state of the spin-1/2 XXZ model with bond alternation. We employ parity-density matrix renormalization group with periodic boundary conditions. The finite-size scaling of Rényi entropies S2 and S∞ are used to construct the phase diagram of the system. The phase diagram displays three possible phases: Haldane type (an example of symmetry protected topological ordered phases), Classical Dimer and Néel phases, the latter bounded by two continuous quantum phase transitions. The entanglement and non-locality in the ground state are studied and quantified by the entanglement convertibility. We found that, at small spatial scales, the ground state is not convertible within the topological Haldane dimer phase. The phenomenology we observe can be described in terms of correlations between edge states. We found that the entanglement spectrum also exhibits a distinctive response in the topological phase: the effective rank of the reduced density matrix displays a specifically large "susceptibility" in the topological phase. These findings support the idea that although the topological order in the ground state cannot be detected by local inspection, the ground state response at local scale can tell the topological phases apart from the non-topological phases.

SA43. Personality Meta-Perception is Impaired and Related to Functioning in Schizophrenia

PubMed Central

Shasteen, Jonathon; Ackerman, Robert

2017-01-01

Abstract Background: Inaccurate self-evaluation is common and tied to social dysfunction in people with schizophrenia (SCZ; Gould et al., 2015). The current study examined whether (1) understanding how others view one’s own personality (i.e., meta-perception) is impaired and (2) meta-perception is related to social competence in SCZ. Methods: In Phase 1, 30 people with SCZ and 30 healthy controls (HC) matched on age, race, sex, and education had a videotaped “get to know you” conversation with an experimenter. They then completed a Big Five trait questionnaire (Donnellan et al., 2006) with the goal of predicting how unfamiliar strangers who view their videos would rate them. Those with SCZ also engaged in a role-play task (Patterson et al., 2001) coded for social competence. In Phase 2, undergraduates unfamiliar with Phase 1 participants watched Phase 1 videos and rated the target’s personality. Undergraduates’ ratings served as “The Truth” to which Phase 1 meta-perceptions (“MPs”) were compared. Group differences in Consistency (i.e., how much The Truth predicts Phase 1 MPs) and Bias (i.e., how much Phase 1 MPs under- or overestimate The Truth) were assessed using the Truth and Bias Model of Judgment (West & Kenny, 2011). Via multiple linear regression, this technique predicted Phase 1 MPs as a function of The Truth for each Big Five trait. The first analyses included group as a predictor to test group differences in Consistency and Bias; the final analyses included social competence as a predictor to test whether Consistency and Bias depend on social competence in SCZ. Results: Consistency: Across group, Consistency was strong; higher values of The Truth predicted higher Phase 1 MPs for all traits (ps≤.001). However, Consistency was weaker in SCZ than in HC for Openness to Experience, Conscientiousness, and Agreeableness (Ps ≤ .009). Similar patterns emerged for Extraversion and Neuroticism, but neither reached significance (Ps ≥ .102). Bias: Across group, Phase 1 MPs overestimated The Truth for Openness to Experience, Conscientiousness, and Agreeableness (Ps ≤ .001). A similar pattern emerged for Extraversion, but it did not reach significance (P = .330). Across group, Phase 1 MPs underestimated The Truth for Neuroticism (P < .001). Bias depended on group for one trait: SCZ overestimated Openness to Experience more than HC did (P = .027). Social competence: In the SCZ group, higher social competence predicted less overestimation of Openness to Experience, Conscientiousness, Extraversion, and Agreeableness (Ps ≤ .049) and less underestimation of Neuroticism (P = .006). Conclusion: Our results indicate that the ability to perceive how others view one’s own personality is impaired in people with SCZ. Moreover, those with SCZ who are less biased in these perceptions seem to be more socially competent. Future work should clarify mechanisms underlying personality meta-perception, its role in social dysfunction, and its potential as a treatment target in SCZ.

Groundwater Hydrology and Chemistry in and near an Emulsified Vegetable-Oil Injection Zone, Solid Waste Management Unit 17, Naval Weapons Station Charleston, North Charleston, South Carolina, 2004-2009

USGS Publications Warehouse

Vroblesky, Don A.; Petkewich, Matthew D.; Lowery, Mark A.; Conlon, Kevin J.; Casey, Clifton C.

2010-01-01

The U.S. Geological Survey and the Naval Facilities Engineering Command Southeast investigated the hydrology and groundwater chemistry in the vicinity of an emulsified vegetable-oil injection zone at Solid Waste Management Unit (SWMU) 17, Naval Weapons Station Charleston, North Charleston, South Carolina. In May 2004, Solutions-IES initiated a Phase-I pilot-scale treatability study at SWMU17 involving the injection of an edible oil emulsion into the aquifer near wells 17PS-01, 17PS-02, and 17PS-03 to treat chlorinated solvents. The Phase-I injection of emulsified vegetable oil resulted in dechlorination of trichloroethene (TCE) to cis-1,2-dichloroethene (cDCE), but the dechlorination activity appeared to stall at cDCE, with little further dechlorination of cDCE to vinyl chloride (VC) or to ethene. The purpose of the present investigation was to examine the groundwater hydrology and chemistry in and near the injection zone to gain a better understanding of the apparent remediation stall. It is unlikely that the remediation stall was due to the lack of an appropriate microbial community because groundwater samples showed the presence of Dehalococcoides species (sp.) and suitable enyzmes. The probable causes of the stall were heterogeneous distribution of the injectate and development of low-pH conditions in the injection area. Because groundwater pH values in the injection area were below the range considered optimum for dechlorination activity, a series of tests was done to examine the effect on dechlorination of increasing the pH within well 17PS-02. During and following the in-well pH-adjustment tests, VC concentrations gradually increased in some wells in the injection zone that were not part of the in-well pH-adjustment tests. These data possibly reflect a gradual microbial acclimation to the low-pH conditions produced by the injection. In contrast, a distinct increase in VC concentration was observed in well 17PS-02 following the in-well pH increase. Adjustment of the pH to near-neutral values in well 17PS-02 may have made that well relatively favorable to VC production compared with much of the rest of the injection zone, possibly accounting for acceleration of VC production at that well. Following a Phase-II injection in which Solutions-IES, Inc., injected pH-buffered emulsified vegetable oil with an improved efficiency injection approach, 1,1-dichloroethene, TCE, and cDCE rapidly decreased in concentration and are now (2009) undetectable in the injection zone, with the exception of a low concentration (43 micrograms per liter, August 2009) of cDCE in well 17PS-01. In August 2009, VC was still present in groundwater at the test wells in concentrations ranging from 150 to 640 micrograms per liter. The Phase-II injection, however, appears to have locally decreased aquifer permeability, possibly resulting in movement of contamination around, rather than through, the treatment area.

Laser-free RF-gun as a combined source of THz and ps-sub-ps X-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agustsson, R.; Boucher, S.; Finn, O.

A coherent, mm-sub-mm-wave source driven by a RF electron gun is proposed for wide research applications as well as auxiliary inspection and screening, safe imaging, cancer diagnostics, surface defectoscopy, and enhanced time-domain spectroscopy. It allows generation of high peak and average THz-sub-THz radiation power provided by beam pre-bunching and chirping in the RF gun followed by microbunching in magnetic compressor, and resonant Cherenkov radiation of an essentially flat beam in a robust, ~inch-long, planar, mm-sub-mm gap structure. The proof-of-principle has been successfully demonstrated in Phase I on a 5 MeV beam of L-band thermionic injector of Idaho Accelerator Center. Themore » system can also deliver an intense, ps-sub-ps bursts of low-to-moderate dose of relativistic electrons and X-ray radiation produced by the same beam required for pulsed radiolysis as well as to enhance screening efficiency, throughput and safety.« less

Laser-free RF-gun as a combined source of THz and ps-sub-ps X-rays

DOE PAGES

Agustsson, R.; Boucher, S.; Finn, O.; ...

2015-01-01

A coherent, mm-sub-mm-wave source driven by a RF electron gun is proposed for wide research applications as well as auxiliary inspection and screening, safe imaging, cancer diagnostics, surface defectoscopy, and enhanced time-domain spectroscopy. It allows generation of high peak and average THz-sub-THz radiation power provided by beam pre-bunching and chirping in the RF gun followed by microbunching in magnetic compressor, and resonant Cherenkov radiation of an essentially flat beam in a robust, ~inch-long, planar, mm-sub-mm gap structure. The proof-of-principle has been successfully demonstrated in Phase I on a 5 MeV beam of L-band thermionic injector of Idaho Accelerator Center. Themore » system can also deliver an intense, ps-sub-ps bursts of low-to-moderate dose of relativistic electrons and X-ray radiation produced by the same beam required for pulsed radiolysis as well as to enhance screening efficiency, throughput and safety.« less

Epitaxial Ge2Sb2Te5 probed by single cycle THz pulses of coherent synchrotron radiation

NASA Astrophysics Data System (ADS)

Bragaglia, V.; Schnegg, A.; Calarco, R.; Holldack, K.

2016-10-01

A THz-probe spectroscopy scheme with laser-induced single cycle pulses of coherent synchrotron radiation is devised and adapted to reveal the dynamic THz transmittance response in epitaxially grown phase change materials upon 800 nm fs-laser excitation. Amorphous (a-) and crystalline (c-) films of the prototypical Ge2Sb2Te5 (GST) alloy are probed with single cycle THz pulses tuned to the spectral range of the highest absorption contrast at 2 THz. After an initial instantaneous sub-picosecond (ps) dynamic THz transmittance drop, the response of a-GST in that range is dominated only by a short recovery time τshort = 2 ps of the excited carriers. On the contrary, the behavior of the c-GST response displays a short decay of 0.85 ps followed by a long one τlong = 90 ps, suggesting that vacancy layers in an ordered c-GST play a role as dissipation channel for photo-induced free carriers.

Intermolecular Structural Change for Thermoswitchable Polymeric Photosensitizer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Wooram; Park, Sin-Jung; Cho, Soojeong

2016-08-17

A switchable photosensitizer (PS), which can be activated at a spe-cific condition beside light, has tremendous advantages for photo-dynamic therapy (PDT). Herein, we developed a thermo-switchable polymeric photosensitizer (T-PPS) by conjugating PS (Pheophor-bide-a, PPb-a) to a temperature-responsive polymer backbone of biocompatible hydroxypropyl cellulose (HPC). Self-quenched PS molecules linked in close proximity by pi-pi stacking in T-PPS were easily transited to an active monomeric state by the tempera-ture induced phase transition of polymer backbones. The tempera-ture responsive inter-molecular interaction changes of PS molecules in T-PPS were demonstrated in synchrotron small-angle X-ray scattering (SAXS) and UV-Vis spectrophotometer analysis. The T-PPS allowed switchablemore » activation and synergistically enhanced cancer cell killing effect at the hyperthermia temperature (45 °C). Our developed T-PPS has the considerable potential not only as a new class of photomedicine in clinics but also as a biosensor based on temperature responsiveness.« less

Nanoscaled Na3PS4 Solid Electrolyte for All-Solid-State FeS2/Na Batteries with Ultrahigh Initial Coulombic Efficiency of 95% and Excellent Cyclic Performances.

PubMed

Wan, Hongli; Mwizerwa, Jean Pierre; Qi, Xingguo; Xu, Xiaoxiong; Li, Hong; Zhang, Qiang; Cai, Liangting; Hu, Yong-Sheng; Yao, Xiayin

2018-04-18

Nanosized Na 3 PS 4 solid electrolyte with an ionic conductivity of 8.44 × 10 -5 S cm -1 at room temperature is synthesized by a liquid-phase reaction. The resultant all-solid-state FeS 2 /Na 3 PS 4 /Na batteries show an extraordinary high initial Coulombic efficiency of 95% and demonstrate high energy density of 611 Wh kg -1 at current density of 20 mA g -1 at room temperature. The outstanding performances of the battery can be ascribed to good interface compatibility and intimate solid-solid contact at FeS 2 electrode/nanosized Na 3 PS 4 solid electrolytes interface. Meanwhile, excellent cycling stability is achieved for the battery after cycling at 60 mA g -1 for 100 cycles, showing a high capacity of 287 mAh g -1 with the capacity retention of 80%.

Research of beam smoothing technologies using CPP, SSD, and PS

NASA Astrophysics Data System (ADS)

Zhang, Rui; Su, Jingqin; Hu, Dongxia; Li, Ping; Yuan, Haoyu; Zhou, Wei; Yuan, Qiang; Wang, Yuancheng; Tian, Xiaocheng; Xu, Dangpeng; Dong, Jun; Zhu, Qihua

2015-02-01

Precise physical experiments place strict requirements on target illumination uniformity in Inertial Confinement Fusion. To obtain a smoother focal spot and suppress transverse SBS in large aperture optics, Multi-FM smoothing by spectral dispersion (SSD) was studied combined with continuous phase plate (CPP) and polarization smoothing (PS). New ways of PS are being developed to improve the laser irradiation uniformity and solve LPI problems in indirect-drive laser fusion. The near field and far field properties of beams using polarization smoothing were studied and compared, including birefringent wedge and polarization control array. As more parameters can be manipulated in a combined beam smoothing scheme, quad beam smoothing was also studies. Simulation results indicate through adjusting dispersion directions of one-dimensional (1-D) SSD beams in a quad, two-dimensional SSD can be obtained. Experiments have been done on SG-III laser facility using CPP and Multi-FM SSD. The research provides some theoretical and experimental basis for the application of CPP, SSD and PS on high-power laser facilities.

PAPR reduction and receiver sensitivity improvement in 16QAM-OFDM RoF system using DMT modulation and BTN-PS technique

NASA Astrophysics Data System (ADS)

Shao, Yufeng

2016-03-01

In this letter, we present the generation, the peak-to average power ratio (PAPR) reduction, the heterodyne detection, the self-mixing reception, and the transmission performance evaluation of 16QAM-OFDM signals in 60 GHz radio over fiber (RoF) system using Discrete multitone (DMT) modulation and Better Than Nyquist pulse shaping (BTN-PS) technique. DMT modulation is introduced in the RoF system, in-phase and quadrature (IQ) will not be required using BTN-PS method, and the computation complexity is much lower than other published techniques for reduced PAPR in the RoF system. In the experiment, 5 Gb/s 16QAM-OFDM downlink signals are transmitted over 42 km SMF-28 and a 0.4 m wireless channel. The experimental results show that the receiver sensitivity is effectively enhanced using this method. Therefore, the introduced BTN-PS technique and its application is a competitive scheme for reducing PAPR, and enhancing the receiver sensitivity in future RoF system.

New Light Sources and Concepts for Electro-Optic Sampling

DTIC Science & Technology

1994-03-01

Research to improve electro - optic sampling led to the development of several high performance optical phase modulators. These phase modulators serve...method of optical pulse shape measurement was demonstrated with 3 ps time resolution, excellent power sensitivity and relative system simplicity. These experiments have opened up the field of temporal optics. Electro - optic sampling.

Pressure Induced Phase Transformations of Silica Polymorphs and Glasses

NASA Astrophysics Data System (ADS)

Cagin, Tahir; Demiralp, Ersan; Goddard, William A., III

1998-03-01

Silica, SiO_2, is one of the most widely studied substance, and it has some complex and unusual properties. We have used a recently developed 2-body interaction force field (E. Demiralp, T. Cagin, W.A. Goddard, III, unpublished.) to study the structural phase transformations in silica under various pressure loading conditions. The specific transformations we studied are α-quartz to stishovite, coesite to stishovite and fused glass to stishovite-like dense, a dominantly six-coordinated glassy phase. Molecular dynamics simulations are performed under the constant loading rates ranging from 0.1 GPa/ps to 2.0 GPa/ps, pressures upto 100 GPa and at temperatures 300, 500, 700 and 900 K. We observe the crystal to crystal transformations to occur reconstructively, whereas it occurs in a smooth and displacive manner from glass to a stishovite-like phase confirming earlier conjectures. (E.M. Stolper and T.J. Ahrens, Geophys. Res. Let.) 14, 1231 (1987). To elucidate the shock loading experiments, we studied the dependence of transition pressure on the loading rate and the temperature. To assess the hysterisis effect we also studied the unloading behavior of each transformation.

Inorganic-Macroion-Induced Formation of Bicontinuous Block Copolymer Nanocomposites with Enhanced Conductivity and Modulus.

PubMed

Zhang, Liying; Cui, Tingting; Cao, Xiao; Zhao, Chengji; Chen, Quan; Wu, Lixin; Li, Haolong

2017-07-24

A facile and electrostatically driven approach has been developed to prepare bicontinuous polymer nanocomposites that is based on the polyoxometalate (POM) macroion induced phase transition of PS-b-P2VP from an initial lamellar phase to a stable bicontinuous phase. The multi-charged POMs can electrostatically cross-link P2VP blocks and give rise to bicontinuous phases in which the POM hybrid conductive domains occupy a large volume fraction of more than 50 %. Furthermore, the POMs can give rise to high proton conductivity and serve as nanoenhancers, endowing the bicontinuous nanocomposites with a conductivity of 0.1 mS cm -1 and a Young's modulus of 7.4 GPa at room temperature; these values are greater than those of pristine PS-b-P2VP by two orders of magnitude and a factor of 1.8, respectively. This approach can provide a new concept based on electrostatic control to design functional bicontinuous polymer materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ionic Salt Effect on the Phase Transition of PS-b-P2VP Copolymers

NASA Astrophysics Data System (ADS)

Kim, Bokyung; An, Hyungju; Ryu, Du Yeol; Kim, Jehan

2009-03-01

Solid-state electrolytes have long been considered as suitable candidates owing to the simple and easy processes for rechargeable battery manufactures, compared to conventional liquid electrolyte counterparts. Especially, polymer/salt systems involving PMMA and PVP complex forms have been studied since they provide stable electrochemical characteristics as well as mechanical properties. We studied the phase behavior of PS-b-P2VP upon the salt addition by small angle x-ray scattering (SAXS) and depolarized light scattering. Transition temperatures of block copolymer were significantly influenced by the salt addition in addition to the changes of d-spacings, which is caused by the effective coordinative interaction between P2VP block and salt. This study suggests a simple approach to solid-state block copolymer electrolytes.

3.375-Gb/s RGB-LED based WDM visible light communication system employing PAM-8 modulation with phase shifted Manchester coding.

PubMed

Chi, Nan; Zhang, Mengjie; Zhou, Yingjun; Zhao, Jiaqi

2016-09-19

Optical background noise and second-order nonlinear distortions are two main challenges faced by indoor high-speed VLC system. In this paper, a novel phase shifted Manchester (PS-Manchester) coding based on PAM-8 is proposed and experimentally demonstrated to mitigate these noise and distortions. With the aid of PS-Manchester coding and WDM, a total data rate of 3.375-Gb/s can be successfully achieved in the RGB-LED based VLC system. The BER is under 7% HD-FEC limit of 3.8x10^-3 after 1-m indoor free space transmission. To the best of our knowledge, this is the highest data rate ever achieved in PAM VLC systems.

Kinetics of Phase Transition from Lamellar to Hexagonally Packed Cylinders for a Triblock Copolymer in a Selective Solvent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu,Y.; Li, M.; Bansil, R.

2007-01-01

We examined the kinetics of the transformation from the lamellar (LAM) to the hexagonally packed cylinder (HEX) phase for the triblock copolymer, polystyrene-b-poly (ethylene-co-butylene)-b-polystyrene (SEBS) in dibutyl phthalate (DBP), a selective solvent for polystyrene (PS), using time-resolved small-angle X-ray scattering (SAXS). We observe the HEX phase with the EB block in the cores at a lower temperature than that observed for the LAM phase due to the solvent selectivity of DBP for the PS block. Analysis of the SAXS data for a deep temperature quench well below the LAM-HEX transition shows that the transformation occurs in a one-step process. Wemore » calculate the scattering using a geometric model of rippled layers with adjacent layers totally out of phase during the transformation. The agreement of the calculations with the data further supports the continuous transformation mechanism from the LAM to HEX for a deep quench. In contrast, for a shallow quench close to the order-order transition, we find agreement with a two-step nucleation and growth mechanism.« less

Summary of the HypHI Phase 0 experiment and future plans with FRS at GSI (FAIR Phase 0)

NASA Astrophysics Data System (ADS)

Saito, T. R.; Rappold, C.; Bertini, O.; Bianchin, S.; Bozkurt, V.; Geissel, H.; Kavatsyuk, M.; Kim, E.; Ma, Y.; Maas, F.; Minami, S.; Nakajima, D.; Nociforo, C.; Özel-Tashenov, B.; Pochodzalla, J.; Scheidenberger, C.; Yoshida, K.

2016-10-01

Results of the HypHI Phase 0 experiment with the reaction of 6Li+12C at 2 A GeV are summarised. Invariant mass distributions as well as the lifetime measurements for 3ΛH and 4ΛH are discussed. The lifetime values for both the hypernuclei are respectively observed to be 183+42-32 ps and 140+48-33 ps, being significantly shorter than those of the Λ-hyperon. Statistical analyses of existing lifetime data for 3ΛH up to 2014 confirm a significantly short lifetime of 3ΛH, which is not explained by present models. Observed hypernuclear production cross section values for 3ΛH and 4ΛH are also summarised. In addition, observed signals for the final states of d +π- and t +π- are discussed. All the discussions on the results of the HypHI Phase 0 experiment in this article are based on [1-4]. We also present a new proposed experiment with the FRS (FRagment Separator) at GSI (FAIR Phase 0) to improve the precision of the hypernuclear spectroscopy with peripheral heavy ion induced reactions.

Experimental investigation of polarization insensitivity and cascadability with semiconductor optical amplifier-based differential phase-shift keyed wavelength converter

NASA Astrophysics Data System (ADS)

Mao, Yaya; Wu, Chongqing; Liu, Bo; Ullah, Rahat; Tian, Feng

2017-12-01

We experimentally investigate the polarization insensitivity and cascadability of an all-optical wavelength converter for differential phase-shift keyed (DPSK) signals for the first time. The proposed wavelength converter is composed of a one-bit delay interferometer demodulation stage followed by a single semiconductor optical amplifier. The impact of input DPSK signal polarization fluctuation on receiver sensitivity for the converted signal is carried out. It is found that this scheme is almost insensitive to the state of polarization of the input DPSK signal. Furthermore, the cascadability of the converter is demonstrated in a two-path recirculating loop. Error-free transmission is achieved with 20 stage cascaded wavelength conversions over 2800 km, where the power penalty is <3.4 dB at bit error rate of 10-9.

DAC-board based X-band EPR spectrometer with arbitrary waveform control

NASA Astrophysics Data System (ADS)

Kaufmann, Thomas; Keller, Timothy J.; Franck, John M.; Barnes, Ryan P.; Glaser, Steffen J.; Martinis, John M.; Han, Songi

2013-10-01

We present arbitrary control over a homogenous spin system, demonstrated on a simple, home-built, electron paramagnetic resonance (EPR) spectrometer operating at 8-10 GHz (X-band) and controlled by a 1 GHz arbitrary waveform generator (AWG) with 42 dB (i.e. 14-bit) of dynamic range. Such a spectrometer can be relatively easily built from a single DAC (digital to analog converter) board with a modest number of stock components and offers powerful capabilities for automated digital calibration and correction routines that allow it to generate shaped X-band pulses with precise amplitude and phase control. It can precisely tailor the excitation profiles "seen" by the spins in the microwave resonator, based on feedback calibration with experimental input. We demonstrate the capability to generate a variety of pulse shapes, including rectangular, triangular, Gaussian, sinc, and adiabatic rapid passage waveforms. We then show how one can precisely compensate for the distortion and broadening caused by transmission into the microwave cavity in order to optimize corrected waveforms that are distinctly different from the initial, uncorrected waveforms. Specifically, we exploit a narrow EPR signal whose width is finer than the features of any distortions in order to map out the response to a short pulse, which, in turn, yields the precise transfer function of the spectrometer system. This transfer function is found to be consistent for all pulse shapes in the linear response regime. In addition to allowing precise waveform shaping capabilities, the spectrometer presented here offers complete digital control and calibration of the spectrometer that allows one to phase cycle the pulse phase with 0.007° resolution and to specify the inter-pulse delays and pulse durations to ⩽250 ps resolution. The implications and potential applications of these capabilities will be discussed.

Directed reflectivity, long life AMTEC condenser (DRC). Final report of Phase II SBIR program[Alkali Metal ThermoElectric Converter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hunt, Thomas K.

The Alkali Metal Thermal to Electric Converter (AMTEC) is a static energy conversion device that operates at high thermal to electric conversion efficiencies that are essentially independent of size, have reached 19% and are expected to reach 25% to 30% in 1997. AMTEC systems have been chosen by NASA and DOE for spacecraft applications and have considerable promise for a wide variety of terrestrial applications. Reduction of parasitic heat losses in AMTEC systems related to radiative heat transfer from the hot side to the condenser can make a substantial contribution to system efficiency. Through design, analysis and the fabrication andmore » testing of cells and systems, the proposed program to develop a Directed Reflectivity Condenser (DRC) has investigated the feasibility of an improved AMTEC condenser component. Phase 1 work showed the potential for adding from 4% to 7% to overall system efficiency for identical operating conditions using the concept. A detailed thermal analysis of several DRC capped cell designs was carried out and some of the conditions under which a DRC, used as the condenser at an end cap of a cylindrical converter, can reduce thermal radiation related losses were determined. A model experimental converter was built and tested to compare DRC and planar condenser surfaces. The results of both analysis and experiment indicate that for moderate aspect ratios of a cylindrical, end condensed converter, the DRC can reduce overall thermal losses by up to 4%. The initial effort in Phase 2 extended the analysis to a novel 150 watt radial AMTEC cell design. This analysis indicated that for the effective aspect ratio of this new converter design, the system performance at the 100+ watt level was not significantly improved by use of a DRC type condenser surface. Further analyses however showed that for cylindrical, end-condensed converters, optimized for use with internal radiation shields, the use of DRC surfaces on the side walls of the converter could be more effective than on the condenser end surface itself. The experimental work in Phase 2 was intended to incorporate a DRC into this cell design and use its measured performance to refine the state-of-the-art AMTEC analytical models. Because the analysis had indicated that the new radial converter design, which may be useful for systems at the {approx} 100 watt level was not much assisted by the DRC properties, this program was redirected toward the simpler cylindrical converter design with the corner cube surfaces on the side walls. The Phase II program was proposed and planned with a funding level substantially below the maximum potentially available for Phase II programs at that time. At the time, there were two other funded government sponsored programs at AMPS for which positive results of the analyses described in this report were expected to lead to incorporation of the DRC concept into converters scheduled to be built for these programs. The programs of interest were the Air Force program titled ''Radiation Tolerant, Eclipse Compatible, Solar AMTEC System'' (F29601-99-C-0132) and the DOE/NASA Advanced Radioisotope Power System (ARPS) program. Shortly after its start, the Air Force program was canceled due to elimination of AF SBIR funds at AFRL and the ARPS program was reduced to a level that could not support introduction of novel concept testing. As a result of these two circumstances, the direct testing of the DRC concept in a full up converter was not completed in the Phase II period.« less

LABCG2, a New ABC Transporter Implicated in Phosphatidylserine Exposure, Is Involved in the Infectivity and Pathogenicity of Leishmania

PubMed Central

González-Rey, Elena; Delgado, Mario; Castanys, Santiago; Pérez-Victoria, José M.; Gamarro, Francisco

2013-01-01

Leishmaniasis is a neglected disease produced by the intracellular protozoan parasite Leishmania. In the present study, we show that LABCG2, a new ATP-binding cassette half-transporter (ABCG subfamily) from Leishmania, is involved in parasite virulence. Down-regulation of LABCG2 function upon expression of an inactive mutant version of this half-transporter (LABCG2K/M) is shown to reduce the translocation of short-chain analogues of phosphatidylserine (PS). This dominant-negative phenotype is specific for the headgroup of the phospholipid, as the movement of phospholipid analogues of phosphatidylcholine, phosphatidylethanolamine or sphingomyelin is not affected. In addition, promastigotes expressing LABCG2K/M expose less endogenous PS in the stationary phase than control parasites. Transient exposure of PS at the outer leaflet of the plasma membrane is known to be one of the mechanisms used by Leishmania to infect macrophages and to silence their immune response. Stationary phase/metacyclic promastigotes expressing LABCG2K/M are less infective for macrophages and show decreased pathogenesis in a mouse model of cutaneous leishmaniasis. Thus, mice infected with parasites expressing LABCG2K/M did not develop any lesion and showed significantly lower inflammation and parasite burden than mice infected with control parasites. Our results indicate that LABCG2 function is required for the externalization of PS in Leishmania promastigotes, a process that is involved in the virulence of the parasite. PMID:23638200

Improved slow-light performance of 10 Gb/s NRZ, PSBT and DPSK signals in fiber broadband SBS.

PubMed

Yi, Lilin; Jaouen, Yves; Hu, Weisheng; Su, Yikai; Bigo, Sébastien

2007-12-10

We have demonstrated error-free operations of slow-light via stimulated Brillouin scattering (SBS) in optical fiber for 10-Gb/s signals with different modulation formats, including non-return-to-zero (NRZ), phase-shaped binary transmission (PSBT) and differential phase-shiftkeying (DPSK). The SBS gain bandwidth is broadened by using current noise modulation of the pump laser diode. The gain shape is simply controlled by the noise density function. Super-Gaussian noise modulation of the Brillouin pump allows a flat-top and sharp-edge SBS gain spectrum, which can reduce slow-light induced distortion in case of 10-Gb/s NRZ signal. The corresponding maximal delay-time with error-free operation is 35 ps. Then we propose the PSBT format to minimize distortions resulting from SBS filtering effect and dispersion accompanied with slow light because of its high spectral efficiency and strong dispersion tolerance. The sensitivity of the 10-Gb/s PSBT signal is 5.2 dB better than the NRZ case with a same 35-ps delay. The maximal delay of 51 ps with error-free operation has been achieved. Futhermore, the DPSK format is directly demodulated through a Gaussian-shaped SBS gain, which is achieved using Gaussian-noise modulation of the Brillouin pump. The maximal error-free time delay after demodulation of a 10-Gb/s DPSK signal is as high as 81.5 ps, which is the best demonstrated result for 10-Gb/s slow-light.

Fabrication of wafer-scale nanopatterned sapphire substrate through phase separation lithography

NASA Astrophysics Data System (ADS)

Guo, Xu; Ni, Mengyang; Zhuang, Zhe; Dai, Jiangping; Wu, Feixiang; Cui, Yushuang; Yuan, Changsheng; Ge, Haixiong; Chen, Yanfeng

2016-04-01

A phase separation lithography (PSL) based on polymer blend provides an extremely simple, low-cost, and high-throughput way to fabricate wafer-scale disordered nanopatterns. This method was introduced to fabricate nanopatterned sapphire substrates (NPSSs) for GaN-based light-emitting diodes (LEDs). The PSL process only involved in spin-coating of polystyrene (PS)/polyethylene glycol (PEG) polymer blend on sapphire substrate and followed by a development with deionized water to remove PEG moiety. The PS nanoporous network was facilely obtained, and the structural parameters could be effectively tuned by controlling the PS/PEG weight ratio of the spin-coating solution. 2-in. wafer-scale NPSSs were conveniently achieved through the PS nanoporous network in combination with traditional nanofabrication methods, such as O2 reactive ion etching (RIE), e-beam evaporation deposition, liftoff, and chlorine-based RIE. In order to investigate the performance of such NPSSs, typical blue LEDs with emission wavelengths of ~450 nm were grown on the NPSS and a flat sapphire substrate (FSS) by metal-organic chemical vapor deposition, respectively. The integral photoluminescence (PL) intensity of the NPSS LED was enhanced by 32.3 % compared to that of the FSS-LED. The low relative standard deviation of 4.7 % for PL mappings of NPSS LED indicated the high uniformity of PL data across the whole 2-in. wafer. Extremely simple, low cost, and high throughput of the process and the ability to fabricate at the wafer scale make PSL a potential method for production of nanopatterned sapphire substrates.

Development of coatings for automated 96-blade solid phase microextraction-liquid chromatography-tandem mass spectrometry system, capable of extracting a wide polarity range of analytes from biological fluids.

PubMed

Mirnaghi, Fatemeh S; Pawliszyn, Janusz

2012-10-26

This work presents the development and evaluation of biocompatible polyacrylonitrile-polystyrene-divinylbenzene (PAN-PS-DVB) and polyacrylonitrile-phenylboronic acid (PAN-PBA) coatings for automated 96-blades (thin-film) solid phase microextraction (SPME) system, using high performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (MS/MS). The SPME condition was optimized for 60 min equilibrium extraction and 40 min desorption for PAN-PS-DVB, and 120 min equilibrium extraction and 60 min desorption for PAN-PBA for parallel sample preparation of up to 96 samples. The thin film geometry of the SPME blades provided good extraction efficiency due to the larger surface area of the coating, and simultaneous sample preparation provided fast and accurate analysis. The PAN-PS-DVB and PAN-PBA 96-blade SPME coatings were evaluated for extraction of analytes in a wide range of polarity (log P=2.8 to -3.7), and they demonstrated efficient extraction recovery (3.5-98.9% for PAN-PS-DVB and 4.0-74.1% for PAN-PBA) for both polar and non-polar groups of compounds. Reusability, reproducibility, and reliability of the system were evaluated. The results demonstrated that both coatings presented chemical and mechanical stability and long-lasting extraction efficiency for more than 100 usages in phosphate-buffered saline (PBS) and human plasma. Copyright © 2012 Elsevier B.V. All rights reserved.

Optical encryption interface

NASA Technical Reports Server (NTRS)

Jackson, Deborah J. (Inventor)

1998-01-01

An analog optical encryption system based on phase scrambling of two-dimensional optical images and holographic transformation for achieving large encryption keys and high encryption speed. An enciphering interface uses a spatial light modulator for converting a digital data stream into a two dimensional optical image. The optical image is further transformed into a hologram with a random phase distribution. The hologram is converted into digital form for transmission over a shared information channel. A respective deciphering interface at a receiver reverses the encrypting process by using a phase conjugate reconstruction of the phase scrambled hologram.

Aggregation, adsorption, and surface properties of multiply end-functionalized polystyrenes.

PubMed

Ansari, Imtiyaz A; Clarke, Nigel; Hutchings, Lian R; Pillay-Narrainen, Amilcar; Terry, Ann E; Thompson, Richard L; Webster, John R P

2007-04-10

The properties of polystyrene blends containing deuteriopolystyrene, multiply end-functionalized with C8F17 fluorocarbon groups, are strikingly analogous to those of surfactants in solution. These materials, denoted FxdPSy, where x is the number of fluorocarbon groups and y is the molecular weight of the dPS chain in kg/mol, were blended with unfunctionalized polystyrene, hPS. Nuclear reaction analysis experiments show that FxdPSy polymers adsorb spontaneously to solution and blend surfaces, resulting in a reduction in surface energy inferred from contact angle analysis. Aggregation of functionalized polymers in the bulk was found to be sensitive to FxdPSy structure and closely related to surface properties. At low concentrations, the functionalized polymers are freely dispersed in the hPS matrix, and in this range, the surface excess concentration grows sharply with increasing bulk concentration. At higher concentrations, surface excess concentrations and contact angles reach a plateau, small-angle neutron scattering data indicate small micellar aggregates of six to seven F2dPS10 polymer chains and much larger aggregates of F4dPS10. Whereas F2dPS10 aggregates are miscible with the hPS matrix, F4dPS10 forms a separate phase of multilamellar vesicles. Using neutron reflectometry (NR), we found that the extent of the adsorbed layer was approximately half the lamellar spacing of the multilamellar vesicles. NR data were fitted using an error function profile to describe the concentration profile of the adsorbed layer, and reasonable agreement was found with concentration profiles predicted by the SCFT model. The thermodynamic sticking energy of the fluorocarbon-functionalized polymer chains to the blend surface increases from 5.3kBT for x = 2 to 6.6kBT for x = 4 but appears to be somewhat dependent upon the blend concentration.

Intermodal Parametric Frequency Conversion in Optical Fibers

NASA Astrophysics Data System (ADS)

Demas, Jeffrey D.

Lasers are an essential technology enabling countless fields of optics, however, their operation wavelengths are limited to isolated regions across the optical spectrum due to the need for suitable gain media. Parametric frequency conversion (PFC) is an attractive means to convert existing lasers to new colors using nonlinear optical interactions rather than the material properties of the host medium, allowing for the development of high power laser sources across the entire optical spectrum. PFC in bulk chi(2) crystals has led to the development of the optical parametric oscillator, which is currently the standard source for high power light at non-traditional wavelengths in the laboratory setting. Ideally, however, one could implement PFC in an optical fiber, thus leveraging the crucial benefits of a guided-wave geometry: alignment-free, compact, and robust operation. Four-wave mixing (FWM) is a nonlinear effect in optical fibers that can be used to convert frequencies, the major challenge being conservation of momentum, or phase matching, between the interacting light waves. Phase matching can be satisfied through the interaction of different spatial modes in a multi-mode fiber, however, previous demonstrations have been limited by mode stability and narrow-band FWM gain. Alternatively, phase matching within the fundamental mode can be realized in high-confinement waveguides (such as photonic crystal fibers), but achieving the anomalous waveguide dispersion necessary for phase matching at pump wavelengths near ˜1 mum (where the highest power fiber lasers emit) comes at the cost of reducing the effective area of the mode, thus limiting power-handling. Here, we specifically consider the class of Bessel-like LP0,m modes in step-index fibers. It has been shown that these modes can be selectively excited and guided stably for long lengths of fiber, and mode stability increases with mode order 'm'. The effective area of modes in these fibers can be very large (>6000 mum2 demonstrated) and is decoupled from dispersion, allowing for phase matching within a single mode in a power-scalable platform. Furthermore, step-index fibers can guide many different LP0,m modes, allowing access to a highly multi-moded basis set with which to study FWM interactions between different modes. In this thesis we develop techniques to excite, propagate, and characterize LP0,m modes in order to demonstrate FWM in two regimes: monomode interactions comprising waves all belonging to the same mode, and intermodal interactions between different modes. In the monomode regime we demonstrate parametric sources which operate at near-infrared wavelengths under-served by conventional fiber lasers, including 880, 974, 1173, and 1347 nm. The output pulses for these systems are ˜300 ps in duration and reach peak powers of ˜10 kW, representing, to the best our knowledge, the highest peak power fiber laser sources demonstrated at these wavelengths to date. In the intermodal regime, we demonstrate a cascade of FWM processes between different modes that lead to a series of discrete peaks in the visible portion of the spectrum, increasing monotonically in mode order from LP0,7 at 678 nm to LP0,16 at 443 nm. This cascade underscores the huge number of potential FWM interactions between different LP0,m modes available in a highly multi-mode fiber, which scale as N4 for N guided modes. Finally, we demonstrate a novel intermodal FWM process pumped between the LP0,4 and LP0,5 modes of a step-index fiber, which provides broadband FWM gain (63 nm at 1550 nm) while maintaining wavelength separations of nearly an octave (762 nm) - a result that cannot be replicated in the single-mode regime. We seed this process to generate a ˜10 kW, ˜300-ps pulsed fiber laser wavelength-tunable from 786-795 nm; representing a fiber analogue of the ubiquitous Ti:Sapphire laser.

Pressure measurements using hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering.

PubMed

Kearney, Sean P; Danehy, Paul M

2015-09-01

We investigate the feasibility of gas-phase pressure measurements using fs/ps rotational CARS. Femtosecond pump and Stokes pulses impulsively prepare a rotational Raman coherence, which is probed by a high-energy 5-ps pulse introduced at a time delay from the Raman preparation. These ultrafast laser pulses are shorter than collisional-dephasing time scales, enabling a new hybrid time- and frequency-domain detection scheme for pressure. Single-laser-shot rotational CARS spectra were recorded from N2 contained in a room-temperature gas cell for pressures from 0.4 to 3 atm and probe delays ranging from 16 to 298 ps. Sensitivity of the accuracy and precision of the pressure data to probe delay was investigated. The technique exhibits superior precision and comparable accuracy to previous laser-diagnostic pressure measurements.

Formation and photopatterning of nanoporous titania thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Oun-Ho; Cheng, Joy Y.; Kim, Hyun Suk

2007-06-04

Photopatternable nanoporous titania thin films were generated from mixtures of an organic diblock copolymer, poly(styrene-b-ethylene oxide) (PS-b-PEO), and an oligomeric titanate (OT) prepared from a chelated titanium isopropoxide. The PS-b-PEO templates well-defined microdomains in thin films of the mixtures, which upon thermal treatment at 450 deg. C, become nanopores in titania. Average pore size and porosity are controlled by the molecular weight and loading level of the PS-b-PEO, respectively. Patterns of nanoporous titania were created by selectively exposing UV light on the mixture films. The UV irradiation destroys the chelating bond and induces the cross-linking reaction of the OT. Subsequentmore » wet development followed by thermal treatment gives patterned nanoporous films of anatase phase titania.« less

Erlotinib as a single agent in select subsets of patients with advanced non-small-cell lung cancer.

PubMed

Carrión, Ramón Pérez; Gracián, Antonio Cubillo; Hernandez, Pedro Salinas

2007-07-01

Erlotinib is an orally active inhibitor of the epidermal growth factor receptor that is effective for the treatment of non-small-cell lung cancer (NSCLC). Patients with a poor performance status (PS) of 2 constitute up to 40% of advanced NSCLC. This group of patients have a lower life expectancy and are thought to have a greater degree of treatment-related toxicity. The clinical benefit on 238 patients with poor PS included in an open-label, nonrandomized, phase II trial of erlotinib in advanced/metastatic NSCLC was 57.58% defined as complete response plus partial response plus stable disease. Median time to progression was 2.9 months. This review will summarize available data about erlotinib on patients with a PS of 2.

Positron annihilation studies of zirconia doped with metal cations of different valence

NASA Astrophysics Data System (ADS)

Prochazka, I.; Cizek, J.; Melikhova, O.; Konstantinova, T. E.; Danilenko, I. A.; Yashchishyn, I. A.; Anwand, W.; Brauer, G.

2013-06-01

New results obtained by applying positron annihilation spectroscopy to the investigation of zirconia-based nanomaterials doped with metal cations of different valence are reported. The slow-positron implantation spectroscopy combined with Doppler broadening measurements was employed to study the sintering of pressure-compacted nanopowders of tetragonal yttria-stabilised zirconia (t-YSZ) and t-YSZ with chromia additive. Positronium (Ps) formation in t-YSZ was proven by detecting 3γ-annihilations of ortho-Ps and was found to gradually decrease with increasing sintering temperature. A subsurface layer with enhanced 3γ-annihilations, compared to the deeper regions, could be identified. Addition of chromia was found to inhibit Ps formation. In addition, first results of positron lifetime measurements on nanopowders of zirconia phase-stabilised with MgO and CeO2 are presented.

Non-equilibrium phase behavior and friction of confined molecular films under shear: A non-equilibrium molecular dynamics study.

PubMed

Maćkowiak, Sz; Heyes, D M; Dini, D; Brańka, A C

2016-10-28

The phase behavior of a confined liquid at high pressure and shear rate, such as is found in elastohydrodynamic lubrication, can influence the traction characteristics in machine operation. Generic aspects of this behavior are investigated here using Non-equilibrium Molecular Dynamics (NEMD) simulations of confined Lennard-Jones (LJ) films under load with a recently proposed wall-driven shearing method without wall atom tethering [C. Gattinoni et al., Phys. Rev. E 90, 043302 (2014)]. The focus is on thick films in which the nonequilibrium phases formed in the confined region impact on the traction properties. The nonequilibrium phase and tribological diagrams are mapped out in detail as a function of load, wall sliding speed, and atomic scale surface roughness, which is shown can have a significant effect. The transition between these phases is typically not sharp as the external conditions are varied. The magnitude of the friction coefficient depends strongly on the nonequilibrium phase adopted by the confined region of molecules, and in general does not follow the classical friction relations between macroscopic bodies, e.g., the frictional force can decrease with increasing load in the Plug-Slip (PS) region of the phase diagram owing to structural changes induced in the confined film. The friction coefficient can be extremely low (∼0.01) in the PS region as a result of incommensurate alignment between a (100) face-centered cubic wall plane and reconstructed (111) layers of the confined region near the wall. It is possible to exploit hysteresis to retain low friction PS states well into the central localization high wall speed region of the phase diagram. Stick-slip behavior due to periodic in-plane melting of layers in the confined region and subsequent annealing is observed at low wall speeds and moderate external loads. At intermediate wall speeds and pressure values (at least) the friction coefficient decreases with increasing well depth of the LJ potential between the wall atoms, but increases when the attractive part of the potential between wall atoms and confined molecules is made larger.

The development of the Asian Forum for Polar Sciences (AFoPS)

NASA Astrophysics Data System (ADS)

Kim, Yeadong; Jeong, Jihoon

2015-12-01

The Asian Forum for Polar Sciences (AFoPS), an international forum of Asian polar research institutes, was established for the advancement of polar sciences among its members in 2004. The Forum has served as an important medium of Asian collective endeavors for polar affairs in human and information exchange, research collaboration, and logistics cooperation for the last decade. The historical development of the AFoPS in retrospect can be divided into four phases: inception and establishment (2003-2004), growth and expansion (2005-2007), review and restructuring (2008-2011), and achievements and further measures (2012-2014). The progress of the AFoPS has not been linear and this trend will continue into the next decades. The Forum, however, clearly made achievements in this period of time, realizing multilateral research and logistics cooperation that would have been previously unimaginable; by doing so, it has laid the foundation for the future. Responsible for a great portion of the world's polar activities, the AFoPS will rise to meet the expectations of the world by producing notable research output, initiating international cooperative programs, and supporting non-polar Asian countries with education and research collaboration. These are the tasks of the AFoPS for the next decade and they require strategy that promotes and facilitates collaboration in a practical way and draws attention of non-polar Asian countries to the polar sciences.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, Chih-Hao; Yue, Kan; Wang, Jing

Controlling self-assembled nanostructures in thin films allows the bottom-up fabrication of ordered nanoscale patterns. Here we report the unique thickness-dependent phase behavior in thin films of a bolaform-like giant surfactant, which consists of butyl- and hydroxyl-functionalized polyhedral oligomeric silsesquioxane (BPOSS and DPOSS) cages telechelically located at the chain ends of a polystyrene (PS) chain with 28 repeating monomers on average. In the bulk, BPOSS-PS28-DPOSS forms a double gyroid (DG) phase. Both grazing incidence small angle X-ray scattering and transmission electron microscopy techniques are combined to elucidate the thin film structures. Interestingly, films with thicknesses thinner than 200 nm exhibit anmore » irreversible phase transition from hexagonal perforated layer (HPL) to compressed hexagonally packed cylinders (c-HEX) at 130 °C, while films with thickness larger than 200 nm show an irreversible transition from HPL to DG at 200 °C. The thickness-controlled transition pathway suggests possibilities to obtain diverse patterns via thin film self-assembly.« less

Investigations on the Phase Diagram and Interaction Parameter of Poly(styrene-b-1,3-cyclohexadiene) Copolymers

DOE PAGES

Misichronis, Konstantinos; Chen, Jihua; Imel, Adam; ...

2017-03-15

A series of linear diblock copolymers containing polystyrene (PS) and poly(1,3-cyclohexadiene) (PCHD) with high 1,4-microstructure (>87%) was synthesized by anionic polymerization and high vacuum techniques. Microphase separation in the bulk was examined in this paper by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) and compared to computational analysis of the predicted morphological phase diagram for this system. Because of the high conformational asymmetry between PS and PCHD, these materials self-assemble into typical morphologies expected for linear diblock copolymer systems and atypical structures. Rheological measurements were conducted and revealed order–disorder transition temperatures (T ODT), for the first time formore » PS-b-PCHD copolymers, resulting in a working expression for the effective interaction parameter χ eff = 32/T – 0.016. Furthermore, we performed computational studies that coincide with the experimental results. Finally, these copolymers exhibit well-ordered structures even at high temperatures (~260 °C) therefore providing a better insight concerning their microphase separation at the nanoscale which is important for their potential use in nanotechnology and/or nanolithography applications.« less

Influence of the capillary on the ignition of the transient spark discharge

NASA Astrophysics Data System (ADS)

Gerling, T.; Hoder, T.; Brandenburg, R.; Bussiahn, R.; Weltmann, K.-D.

2013-04-01

A self-pulsing negative dc discharge in argon generated in a needle-to-plane geometry at open atmosphere is investigated. Additionally, the needle electrode can be surrounded by a quartz capillary. It is shown that the relative position of the capillary end to the needle tip strongly influences the discharge inception and its spatio-temporal dynamics. Without the capillary for the selected working parameters a streamer corona is ignited, but when the capillary surrounds the needle, the transient spark (TS) discharge is ignited after a pre-streamer (PS) occurs. The time between PS and TS discharge depends on the relative capillary end position. The existence of the PS is confirmed by electro-optical characterization. Furthermore, spectrally and spatio-temporally resolved cross-correlation spectroscopy is applied to show the most active region of pre-phase emission activity as indicators for high local electric field strength. The results indicate that with a capillary in place, the necessary energy input of the pre-phase into the system is mainly reduced by additional electrical fields at the capillary edge. Even such a small change as a shift of dielectric surface close to the plasma largely changes the energy balance in the system.

RuO2 supported NaY zeolite catalysts: Effect of preparation methods on catalytic performance during aerobic oxidation of benzyl alcohol

NASA Astrophysics Data System (ADS)

Jung, Dasom; Lee, Sunwoo; Na, Kyungsu

2017-10-01

The effects of preparation method for RuO2 supported zeolite catalysts on the catalytic consequences during the aerobic oxidation of benzyl alcohol to benzaldehyde were investigated. Three preparation methods, i.e., (i) simultaneous crystallization of the zeolite framework in the presence of RuCl3 (Ru(SC)/NaY), (ii) post ion-exchange with RuCl3 on the zeolite framework (Ru(IE)/NaY), and (iii) post support of preformed Ru metal nanoparticles on the zeolite surface (Ru(PS)/NaY), were used to construct three different RuO2 supported NaY zeolite catalysts. The catalyst performance was investigated as functions of the reaction time and temperature, in correlation with the structural changes of the catalysts, as analyzed by X-ray diffraction (XRD). The results revealed that the catalytic consequences were dramatically affected by the preparation methods. Although similar conversion was achieved with all three catalysts, the turnover frequency (TOF) differed. The Ru(PS)/NaY catalyst exhibited the highest TOF (33-48 h-1), whereas the other catalysts produced much lower TOFs (9-12 h-1). The Ru(PS)/NaY catalyst also had the highest activation energy (Ea) of 48.39 kJ mol-1, whereas the Ru(SC)/NaY and Ru(IE)/NaY catalysts had Ea values of 18.58 and 24.11 kJ mol-1, respectively. Notably, the Ru(PS)/NaY catalyst yielded a significantly higher pre-exponential factor of 5.22 × 105 h-1, which is about 5 orders of magnitude larger than that of the Ru(SC)/NaY catalyst (7.15 × 100 h-1). This suggests that collision between benzyl alcohol and molecular oxygen was very intensive on the Ru(PS)/NaY catalyst, which explains the higher TOF of the Ru(PS)/NaY catalyst relative to the others in spite of the higher Ea value of the former. In terms of recyclability, the pristine crystallinity of the zeolite framework was maintained in the Ru(SC)/NaY catalyst and the RuO2 phase exhibited an insignificant loss of the initial activity up to three catalytic cycles, whereas Ru(PS)/NaY showed slight loss of activity and Ru(IE)/NaY showed a significant loss of activity due to the disappearance of the RuO2 phase.

Anisotropy variety using and wave splitting analysis by using the integration of combine linear and circlcirculare air-gun shotshooting datasurvey in the gas hydrate-enriched continental slops area o,f southwestenSW Taiwan

NASA Astrophysics Data System (ADS)

Lin, Y. C.; Lin, J. Y.; Cheng, W. B.

2016-12-01

Linear seismic refraction analysis based on air- or GI- gun shootings were widely used to determine the velocity structures along 2-D profiles. The data acquisition along several profiles can provide a 3-D view and increases the knowledge related to the lateral variation for the geological structures. However, if the target area has restricted distribution, the structure may not be observed by large spacing seismic profiles. Furthermore, limited by the network geometry, it could be difficult to get the velocity variation for different azimuths. In this study, apart from traditional linear seismic profile shooting geometry, we applied a circular shooting track around a 4-components Ocean-Bottom seismometer (OBS) station deployed in 2014 and 2015 on the continental slops, a hydrate-enriched area in the SW Taiwan, with a radius of 1 mile and 1.5 mile respectively. The aim is to understand if the change of shooting geometry along a single station can provide lateral information about the bathymetry characteristics or velocity composition in the sediment. To better examine the spatial variation of our data, we first rotated the OBS records to the vertical (V), radial (R) and transverse (T) components based the 3-axie rotate method. Distinct changes in the signal intensity in T component were distinguished at depths of 4.5 second between 58-157 degrees and at depths of 4 second between 212-258 degrees. The OBS is located on a sedimentary wedge dipping northeastward, as evidenced by the multichannel reflection profiles shown in the previous study. The ongoing upward activity of the mud diapir do the generation this sedimentary wedge Thus, the appearance of these signals could be linked to the wave refraction from the layer of the wedge, where a clear velocity contrast could be expected. We recognized visible P-S converted phase in R component at depths of approximately at depth of 3.3 second. The time arrivals of the converted phases provide information for the estimation of S wave velocity, which could be a good indicator for the sediment strength. Based on the arrivals, we suggest that the formation of the converted wave should be linked to the bathymetry alteration. Our results show that the experiment along a circular shooting track could bring useful information about the anisotropy characteristics around the OBS site.

Cascaded Converters for Integration and Management of Grid Level Energy Storage Systems

NASA Astrophysics Data System (ADS)

Alaas, Zuhair

This research work proposes two cascaded multilevel inverter structures for BESS. The gating and switching control of switching devices in both inverter typologies are done by using a phase-shifted PWM scheme. The first proposed isolated multilevel inverter is made up of three-phase six-switch inverter blocks with a reduced number of power components compared with traditional isolated CHB. The suggested isolated converter has only one battery string for three-phase system that can be used for high voltage and high power applications such as grid connected BESS and alternative energy systems. The isolated inverter enables dq frame based simple control and eliminates the issues of single-phase pulsating power, which can cause detrimental impacts on certain dc sources. Simulation studies have been carried out to compare the proposed isolated multi-level inverter with an H-bridge cascaded transformer inverter. The simulation results verified the performance of the isolated inverter. The second proposed topology is a Hierarchal Cascaded Multilevel Converter (HCMC) with phase to phase SOC balancing capability which also for high voltage and high power battery energy storage systems. The HCMC has a hybrid structure of half-bridge converters and H-bridge inverters and the voltage can be hierarchically cascaded to reach the desired value at the half-bridge and the H-bridge levels. The uniform SOC battery management is achieved by controlling the half-bridge converters that are connected to individual battery modules/cells. Simulation studies and experimental results have been carried on a large scale battery system under different operating conditions to verify the effectiveness of the proposed inverters. Moreover, this dissertation presents a new three-phase SOC equalizing circuit, called six-switch energy-level balancing circuit (SSBC), which can be used to realize uniform SOC operation for full utilization of the battery capacity in proposed HCMC or any CMI inverter while keeping balanced three-phase operation. A sinusoidal PWM modulation technique is used to control power transferring between phases. Simulation results have been carried out to verify the performance of the proposed SSBC circuit of uniform three-phase SOC balancing.

Coupling hydrothermal liquefaction and anaerobic digestion for energy valorization from model biomass feedstocks.

PubMed

Posmanik, Roy; Labatut, Rodrigo A; Kim, Andrew H; Usack, Joseph G; Tester, Jefferson W; Angenent, Largus T

2017-06-01

Hydrothermal liquefaction converts food waste into oil and a carbon-rich hydrothermal aqueous phase. The hydrothermal aqueous phase may be converted to biomethane via anaerobic digestion. Here, the feasibility of coupling hydrothermal liquefaction and anaerobic digestion for the conversion of food waste into energy products was examined. A mixture of polysaccharides, proteins, and lipids, representing food waste, underwent hydrothermal processing at temperatures ranging from 200 to 350°C. The anaerobic biodegradability of the hydrothermal aqueous phase was examined through conducting biochemical methane potential assays. The results demonstrate that the anaerobic biodegradability of the hydrothermal aqueous phase was lower when the temperature of hydrothermal processing increased. The chemical composition of the hydrothermal aqueous phase affected the anaerobic biodegradability. However, no inhibition of biodegradation was observed for most samples. Combining hydrothermal and anaerobic digestion may, therefore, yield a higher energetic return by converting the feedstock into oil and biomethane. Copyright © 2017 Elsevier Ltd. All rights reserved.

In-depth study of single photon time resolution for the Philips digital silicon photomultiplier

NASA Astrophysics Data System (ADS)

Liu, Z.; Gundacker, S.; Pizzichemi, M.; Ghezzi, A.; Auffray, E.; Lecoq, P.; Paganoni, M.

2016-06-01

The digital silicon photomultiplier (SiPM) has been commercialised by Philips as an innovative technology compared to analog silicon photomultiplier devices. The Philips digital SiPM, has a pair of time to digital converters (TDCs) connected to 12800 single photon avalanche diodes (SPADs). Detailed measurements were performed to understand the low photon time response of the Philips digital SiPM. The single photon time resolution (SPTR) of every single SPAD in a pixel consisting of 3200 SPADs was measured and an average value of 85 ps full width at half maximum (FWHM) was observed. Each SPAD sends the signal to the TDC with different signal propagation time, resulting in a so called trigger network skew. This distribution of the trigger network skew for a pixel (3200 SPADs) has been measured and a variation of 50 ps FWHM was extracted. The SPTR of the whole pixel is the combination of SPAD jitter, trigger network skew, and the SPAD non-uniformity. The SPTR of a complete pixel was 103 ps FWHM at 3.3 V above breakdown voltage. Further, the effect of the crosstalk at a low photon level has been studied, with the two photon time resolution degrading if the events are a combination of detected (true) photons and crosstalk events. Finally, the time response to multiple photons was investigated.

Optoelectronic Picosecond Detection of Synchrotron X-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Durbin, Stephen M.

2017-08-04

The goal of this research program was to develop a detector that would measure x-ray time profiles with picosecond resolution. This was specifically aimed for use at x-ray synchrotrons, where x-ray pulse profiles have Gaussian time spreads of 50-100 ps (FWHM), so the successful development of such a detector with picosecond resolution would permit x-ray synchrotron studies to break through the pulse width barrier. That is, synchrotron time-resolved studies are currently limited to pump-probe studies that cannot reveal dynamics faster than ~50 ps, whereas the proposed detector would push this into the physically important 1 ps domain. The results ofmore » this research effort, described in detail below, are twofold: 1) the original plan to rely on converting electronic signals from a semiconductor sensor into an optical signal proved to be insufficient for generating signals with the necessary time resolution and sensitivity to be widely applicable; and 2) an all-optical method was discovered whereby the x-rays are directly absorbed in an optoelectronic material, lithium tantalate, which can then be probed by laser pulses with the desired picosecond sensitivity for detection of synchrotron x-rays. This research program has also produced new fundamental understanding of the interaction of x-rays and optical lasers in materials that has now created a viable path for true picosecond detection of synchrotron x-rays.« less

Evaluation of quadrature-phase-shift-keying signal characteristics in W-band radio-over-fiber transmission using direct in-phase/quadrature-phase conversion technique

NASA Astrophysics Data System (ADS)

Suzuki, Meisaku; Kanno, Atsushi; Yamamoto, Naokatsu; Sotobayashi, Hideyuki

2016-02-01

The effects of in-phase/quadrature-phase (IQ) imbalances are evaluated with a direct IQ down-converter in the W-band (75-110 GHz). The IQ imbalance of the converter is measured within a range of +/-10 degrees in an intermediate frequency of DC-26.5 GHz. 1-8-G-baud quadrature phase-shift keying (QPSK) signals are transmitted successfully with observed bit error rates within a forward error correction limit of 2×10-3 using radio over fiber (RoF) techniques. The direct down-conversion technique is applicable to next-generation high-speed wireless access communication systems in the millimeter-wave band.

High power density dc/dc converter: Selection of converter topology

NASA Technical Reports Server (NTRS)

Divan, Deepakraj M.

1990-01-01

The work involved in the identification and selection of a suitable converter topology is described. Three new dc/dc converter topologies are proposed: Phase-Shifted Single Active Bridge DC/DC Converter; Single Phase Dual Active Bridges DC/DC Converter; and Three Phase Dual Active Bridges DC/DC Converter (Topology C). The salient features of these topologies are: (1) All are minimal in structure, i.e., each consists of an input and output bridge, input and output filter and a transformer, all components essential for a high power dc/dc conversion process; (2) All devices of both the bridges can operate under near zero-voltage conditions, making possible a reduction of device switching losses and hence, an increase in switching frequency; (3) All circuits operate at a constant frequency, thus simplifying the task of the magnetic and filter elements; (4) Since, the leakage inductance of the transformer is used as the main current transfer element, problems associated with the diode reverse recovery are eliminated. Also, this mode of operation allows easy paralleling of multiple modules for extending the power capacity of the system; (5) All circuits are least sensitive to parasitic impedances, infact the parasitics are efficently utilized; and (6) The soft switching transitions, result in low electromagnetic interference. A detailed analysis of each topology was carried out. Based on the analysis, the various device and component ratings for each topology operating at an optimum point, and under the given specifications, are tabulated and discussed.

All-digital pulse-expansion-based CMOS digital-to-time converter.

PubMed

Chen, Chun-Chi; Chu, Che-Hsun

2017-02-01

This paper presents a new all-digital CMOS digital-to-time converter (DTC) based on pulse expansion. Pulse expansion is achieved using an all-digital pulse-mixing scheme that can effectively improve the timing resolution and enable the DTC to be concise. Without requiring the Vernier principle or a costly digital-to-analog converter, the DTC comprises a pulse generator for generating a pulse, a pulse-expanding circuit (PEC) for programming timing generation, and a time subtractor for removing the time width of the pulse. The PEC comprises only a delay chain composed of proposed pulse-expanding units and a multiplexer. For accuracy enhancement, a pulse neutralization technique is presented to eliminate undesirable pulse variation. A 4-bit converter was fabricated in a 0.35-μm Taiwan Semiconductor Manufacturing Company CMOS process and had a small area of nearly 0.045 mm 2 . Six chips were tested, all of which exhibited an improved resolution (approximately 16 ps) and low integral nonlinearity (less than ±0.4 least significant bit). The power consumption was 0.2 mW when the sample rate was 1M samples/s and the voltage supply was 3.3 V. The proposed DTC not only has favorable cost and power but also achieves an acceptable resolution without requiring an advanced CMOS process. This study is the first to use pulse expansion in digital-to-time conversion.

All-digital pulse-expansion-based CMOS digital-to-time converter

NASA Astrophysics Data System (ADS)

Chen, Chun-Chi; Chu, Che-Hsun

2017-02-01

This paper presents a new all-digital CMOS digital-to-time converter (DTC) based on pulse expansion. Pulse expansion is achieved using an all-digital pulse-mixing scheme that can effectively improve the timing resolution and enable the DTC to be concise. Without requiring the Vernier principle or a costly digital-to-analog converter, the DTC comprises a pulse generator for generating a pulse, a pulse-expanding circuit (PEC) for programming timing generation, and a time subtractor for removing the time width of the pulse. The PEC comprises only a delay chain composed of proposed pulse-expanding units and a multiplexer. For accuracy enhancement, a pulse neutralization technique is presented to eliminate undesirable pulse variation. A 4-bit converter was fabricated in a 0.35-μ m Taiwan Semiconductor Manufacturing Company CMOS process and had a small area of nearly 0.045 mm2. Six chips were tested, all of which exhibited an improved resolution (approximately 16 ps) and low integral nonlinearity (less than ±0.4 least significant bit). The power consumption was 0.2 mW when the sample rate was 1M samples/s and the voltage supply was 3.3 V. The proposed DTC not only has favorable cost and power but also achieves an acceptable resolution without requiring an advanced CMOS process. This study is the first to use pulse expansion in digital-to-time conversion.

Dual Imprinted Polymer Thin Films via Pattern Directed Self-Organization.

PubMed

Grolman, Danielle; Bandyopadhyay, Diya; Al-Enizi, Abdullah; Elzatahry, Ahmed; Karim, Alamgir

2017-06-21

Synthetic topographically patterned films and coatings are typically contoured on one side, yet many of nature's surfaces have distinct textures on different surfaces of the same object. Common examples are the top and bottom sides of the butterfly wing or lotus leaf, onion shells, and the inside versus outside of the stem of a flower. Inspired by nature, we create dual (top and bottom) channel patterned polymer films. To this end, we first develop a novel fabrication method to create ceramic line channel relief structures by converting the oligomeric residue of stamped poly(dimethylsiloxane) (PDMS) nanopatterns on silicon substrates to glass (SiOx, silica) by ultraviolet-ozone (UVO) exposure. These silica patterned substrates are flow coated with polystyrene (PS) films and confined within an identically patterned top confining soft PDMS elastomer film. Annealing of the sandwich structures drives the PS to rapidly mold fill the top PDMS pattern in conjunction with a dewetting tendency of the PS on the silica pattern. Varying the film thickness h, from less than to greater than the pattern height, and varying the relative angle between the top-down and bottom-up patterned confinement surfaces create interesting uniform and nonuniform digitized defects in PS channel patterns, as also a defect-free channel regime. Our dual patterned polymer channels provide a novel fabrication route to topographically imprinted Moiré patterns (whose applications range from security encrypting holograms to sensitive strain gauges), and their basic laser light diffractions properties are illustrated and compared to graphical simulations and 2D-FFT of real-space AFM channel patterns. While traditional "geometrical" and "fringe" Moiré patterns function by superposition of two misaligned optical patterned transmittance gratings, our topographic pattern gratings are quite distinct and may allow for more unique holographic optical characteristics with further development.

Over 10-watt pico-second diffraction-limited output from a Nd:YVO4 slab amplifier with a phase conjugate mirror.

PubMed

Ojima, Yasukuni; Nawata, Kouji; Omatsu, Takashige

2005-10-31

We have produced a high beam quality pico-second laser based on a continuous-wave diode pumped Nd:YVO4 slab amplifier with a photorefractive phase conjugate mirror. 12.8W diffraction-limited output with a pulse width of 8.7ps was obtained.

PS-341 in Treating Patients With Refractory or Relapsed Acute Myeloid Leukemia, Acute Lymphoblastic Leukemia, Chronic Myeloid Leukemia in Blast Phase, or Myelodysplastic Syndrome

ClinicalTrials.gov

2013-01-22

Adult Acute Promyelocytic Leukemia (M3); Blastic Phase Chronic Myelogenous Leukemia; Previously Treated Myelodysplastic Syndromes; Recurrent Adult Acute Lymphoblastic Leukemia; Recurrent Adult Acute Myeloid Leukemia; Refractory Anemia With Excess Blasts; Refractory Anemia With Excess Blasts in Transformation; Relapsing Chronic Myelogenous Leukemia

Nanoporous Silicon Combustion: Observation of Shock Wave and Flame Synthesis of Nanoparticle Silica.

PubMed

Becker, Collin R; Gillen, Greg J; Staymates, Matthew E; Stoldt, Conrad R

2015-11-18

The persistent hydrogen termination present in nanoporous silicon (nPS) is unique compared to other forms of nanoscale silicon (Si) which typically readily form a silicon dioxide passivation layer. The hydrogen terminated surface combined with the extremely high surface area of nPS yields a material capable of powerful exothermic reactions when combined with strong oxidizers. Here, a galvanic etching mechanism is used to produce nPS both in bulk Si wafers as well as in patterned regions of Si wafers with microfabricated ignition wires. An explosive composite is generated by filling the pores with sodium perchlorate (NaClO4). Using high-speed video including Schlieren photography, a shock wave is observed to propagate through air at 1127 ± 116 m/s. Additionally, a fireball is observed above the region of nPS combustion which persists for nearly 3× as long when reacted in air compared to N2, indicating that highly reactive species are generated that can further combust with excess oxygen. Finally, reaction products from either nPS-NaClO4 composites or nPS alone combusted with only high pressure O2 (400 psig) gas as an oxidizer are captured in a calorimeter bomb. The products in both cases are similar and verified by transmission electron microscopy (TEM) to include nano- to micrometer scale SiOx particles. This work highlights the complex oxidation mechanism of nPS composites and demonstrates the ability to use a solid state reaction to create a secondary gas phase combustion.

2-Aminoacetophenone as a potential breath biomarker for Pseudomonas aeruginosa in the cystic fibrosis lung

PubMed Central

2010-01-01

Background Pseudomonas aeruginosa infections are associated with progressive life threatening decline of lung function in cystic fibrosis sufferers. Growth of Ps. aeruginosa releases a "grape-like" odour that has been identified as the microbial volatile organic compound 2-aminoacetophenone (2-AA). Methods We investigated 2-AA for its specificity to Ps. aeruginosa and its suitability as a potential breath biomarker of colonisation or infection by Solid Phase Micro Extraction and Gas Chromatography-Mass Spectrometry (GC/MS). Results Cultures of 20 clinical strains of Ps. aeruginosa but not other respiratory pathogens had high concentrations of 2-AA in the head space of in vitro cultures when analysed by GC/MS. 2-AA was stable for 6 hours in deactivated glass sampling bulbs but was not stable in Tedlar® bags. Optimisation of GC/MS allowed detection levels of 2-AA to low pico mol/mol range in breath. The 2-AA was detected in a significantly higher proportion of subjects colonised with Ps. aeruginosa 15/16 (93.7%) than both the healthy controls 5/17 (29%) (p < 0.0002) and CF patients not colonised with Ps. aeruginosa 4/13(30.7%) (p < 0.001). The sensitivity and specificity of the 2-AA breath test compared to isolation of Ps. aeruginosa in sputum and/or BALF was 93.8% (95% CI, 67-99) and 69.2% (95% CI, 38-89) respectively. The peak integration values for 2-AA analysis in the breath samples were significantly higher in Ps. aeruginosa colonised subjects (median 242, range 0-1243) than the healthy controls (median 0, range 0-161; p < 0.001) and CF subjects not colonised with Ps. aeruginosa (median 0, range 0-287; p < 0.003) Conclusions Our results report 2-AA as a promising breath biomarker for the detection of Ps. aeruginosa infections in the cystic fibrosis lung. PMID:21054900

Isomerization Intermediates In Solution Phase Photochemistry Of Stilbenes

NASA Astrophysics Data System (ADS)

Doany, F. E.; Hochstrasser, R. M.; Greene, B. I.

1985-04-01

Picosecond and subpicosecond spectroscopic studies have revealed evidence for an isomerization intermediate between cis and trans in the photoinduced isomerism of both stilbene and biindanyledene ("stiff" stilbene). In stiff stilbene, a transient absorption at 351 nm displays time evolution and viscosity dependence consistent with absorption by a twisted intermediate ("phantom" state) with a lOps lifetime. An analagous bottleneck state with a life-time of 4ps is also consistent with the ground state recovery dynamics of t-stilbene following excitation of c-stilbene when monitored with 0.1ps resolution.

A High-Performance Recycling Solution for Polystyrene Achieved by the Synthesis of Renewable Poly(thioether) Networks Derived from d-Limonene

PubMed Central

Nash, Landon D.; Rodriguez, Jennifer N.; Lonnecker, Alexander T.; Raymond, Jeffery E.; Wilson, Thomas S.; Wooley, Karen L.; Maitland, Duncan J.

2014-01-01

Nanocomposite polymers have been prepared using a new sustainable materials synthesis process in which d-Limonene functions simultaneously both as a solvent for recycling polystyrene (PS) waste and as a monomer that undergoes UV-catalyzed thiol-ene polymerization reactions with polythiol co-monomers to afford polymeric products comprised of precipitated PS phases dispersed throughout elastomeric poly(thioether) networks. These blended networks exhibit mechanical properties that greatly exceed those of either polystyrene or the poly(thioether) network homopolymers alone. PMID:24249666

A self-determination theory-based self-myofascial release program in older adults with myofascial trigger points in the neck and back: A pilot study.

PubMed

Lee, Minyoung; Kim, Minhee; Oh, Sejun; Choi, Yoon-Jin; Lee, Dongshin; Lee, Sang Heon; Yoon, BumChul

2017-09-01

To examine the effectiveness and adherence to a self-determination theory (SDT)-based self-myofascial release (SMR) program in older adults with myofascial trigger points (MTrPs), and to investigate the factors that influence participant behavioral change while conducting the program in a home setting. An explanatory mixed-method design was used to evaluate a 12-week SDT-based SMR program, including a 4-week group-based education and practice (EP) phase and an 8-week home-based self-management (SM) phase. Pain intensity on palpation and sensitivity to pain were assessed at baseline and the post EP and post SM phase. Focus group interviews were conducted at the post SM phase. Fifteen participants completed the study. Pain intensity and sensitivity to pain significantly improved at the post SM phase compared with the baseline. Adherence increased during the SM phase compared with that during the EP phase. Four main themes emerged as factors that influenced participant behavioral change: 1) "awareness of the effectiveness"; 2) "a sense of duty to perform the exercise"; 3) "obedience to expert instruction"; and 4) "lack of friendship." These results support the effectiveness of an SDT-based SMR program for the treatment of MTrPs and in motivating older adults to participate in the program.

Ramucirumab as second-line treatment in patients with advanced hepatocellular carcinoma following first-line therapy with sorafenib: Patient-focused outcome results from the randomised phase III REACH study.

PubMed

Chau, Ian; Peck-Radosavljevic, Markus; Borg, Christophe; Malfertheiner, Peter; Seitz, Jean Francois; Park, Joon Oh; Ryoo, Baek-Yeol; Yen, Chia-Jui; Kudo, Masatoshi; Poon, Ronnie; Pastorelli, Davide; Blanc, Jean-Frederic; Chung, Hyun Cheol; Baron, Ari D; Okusaka, Takuji; Bowman, L; Cui, Zhanglin Lin; Girvan, Allicia C; Abada, Paolo B; Yang, Ling; Zhu, Andrew X

2017-08-01

To report patient-focused outcomes as measured by quality of life (QoL) and performance status (PS) in REACH, a phase III placebo-controlled randomised study, assessing ramucirumab in advanced hepatocellular carcinoma (HCC) patients who received prior sorafenib. Eligible patients had advanced HCC, Child-Pugh A, PS 0 or 1 and prior sorafenib. Patients received ramucirumab (8 mg/kg) or placebo (1:1) on day 1 of a 2-week cycle. QoL was assessed by FACT Hepatobiliary Symptom Index (FHSI)-8 and EuroQoL (EQ-5D) at baseline; cycles 4, 10, and 16; and end of treatment. PS was assessed at baseline, each cycle, and end of treatment. Deterioration in FHSI-8 was defined as a ≥3-point decrease from baseline and PS deterioration was defined as a change of ≥2. Both intention-to-treat and pre-specified subgroup of patients with baseline serum alpha-fetoprotein (AFP) ≥400 ng/mL were assessed. There were 565 patients randomised to ramucirumab and placebo. Compliance with FHSI and EQ-5D was high and similar between groups. In the ITT population, deterioration in FHSI-8, EQ-5D, and PS was similar between ramucirumab and placebo. In patients with baseline AFP ≥400 ng/mL, ramucirumab significantly reduced deterioration in FHSI-8 at the end of treatment compared with placebo (P = 0.0381), and there was a trend towards a delay in the deterioration of symptoms in FHSI-8 (HR 0.690; P = 0.054) and PS (HR 0.642; P = 0.057) in favour of ramucirumab. We report one of the most comprehensive data sets of QoL and symptom burden in patients undergoing systemic therapy for advanced HCC. Ramucirumab was associated with no worsening of QoL. In patients with baseline AFP ≥400 ng/mL, the significant survival benefit observed in patients treated with ramucirumab was coupled with a trend in patient-focused outcome benefits. NCT01140347. Copyright © 2017 Elsevier Ltd. All rights reserved.

Core-Shell Fe1- xS@Na2.9PS3.95Se0.05 Nanorods for Room Temperature All-Solid-State Sodium Batteries with High Energy Density.

PubMed

Wan, Hongli; Mwizerwa, Jean Pierre; Qi, Xingguo; Liu, Xin; Xu, Xiaoxiong; Li, Hong; Hu, Yong-Sheng; Yao, Xiayin

2018-03-27

High ionic conductivity electrolyte and intimate interfacial contact are crucial factors to realize high-performance all-solid-state sodium batteries. Na 2.9 PS 3.95 Se 0.05 electrolyte with reduced particle size of 500 nm is first synthesized by a simple liquid-phase method and exhibits a high ionic conductivity of 1.21 × 10 -4 S cm -1 , which is comparable with that synthesized with a solid-state reaction. Meanwhile, a general interfacial architecture, that is, Na 2.9 PS 3.95 Se 0.05 electrolyte uniformly anchored on Fe 1- x S nanorods, is designed and successfully prepared by an in situ liquid-phase coating approach, forming core-shell structured Fe 1- x S@Na 2.9 PS 3.95 Se 0.05 nanorods and thus realizing an intimate contact interface. The Fe 1- x S@Na 2.9 PS 3.95 Se 0.05 /Na 2.9 PS 3.95 Se 0.05 /Na all-solid-state sodium battery demonstrates high specific capacity and excellent rate capability at room temperature, showing reversible discharge capacities of 899.2, 795.5, 655.1, 437.9, and 300.4 mAh g -1 at current densities of 20, 50, 100, 150, and 200 mA g -1 , respectively. The obtained all-solid-state sodium batteries show very high energy and power densities up to 910.6 Wh kg -1 and 201.6 W kg -1 based on the mass of Fe 1- x S at current densities of 20 and 200 mA g -1 , respectively. Moreover, the reaction mechanism of Fe 1- x S is confirmed by means of ex situ X-ray diffraction techniques, showing that partially reversible reaction occurs in the Fe 1- x S electrode after the second cycle, which gives the obtained all-solid-state sodium battery an exceptional cycling stability, exhibiting a high capacity of 494.3 mAh g -1 after cycling at 100 mA g -1 for 100 cycles. This contribution provides a strategy for designing high-performance room temperature all-solid-state sodium battery.

Regional fringe analysis for improving depth measurement in phase-shifting fringe projection profilometry

NASA Astrophysics Data System (ADS)

Chien, Kuang-Che Chang; Tu, Han-Yen; Hsieh, Ching-Huang; Cheng, Chau-Jern; Chang, Chun-Yen

2018-01-01

This study proposes a regional fringe analysis (RFA) method to detect the regions of a target object in captured shifted images to improve depth measurement in phase-shifting fringe projection profilometry (PS-FPP). In the RFA method, region-based segmentation is exploited to segment the de-fringed image of a target object, and a multi-level fuzzy-based classification with five presented features is used to analyze and discriminate the regions of an object from the segmented regions, which were associated with explicit fringe information. Then, in the experiment, the performance of the proposed method is tested and evaluated on 26 test cases made of five types of materials. The qualitative and quantitative results demonstrate that the proposed RFA method can effectively detect the desired regions of an object to improve depth measurement in the PS-FPP system.

Metal-organic vapor-phase epitaxy-grown ultra-low density InGaAs/GaAs quantum dots exhibiting cascaded single-photon emission at 1.3 μm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paul, Matthias, E-mail: m.paul@ihfg.uni-stuttgart.de; Kettler, Jan; Zeuner, Katharina

By metal-organic vapor-phase epitaxy, we have fabricated InGaAs quantum dots on GaAs substrate with an ultra-low lateral density (<10{sup 7} cm{sup −2}). The photoluminescence emission from the quantum dots is shifted to the telecom O-band at 1.31 μm by an InGaAs strain reducing layer. In time-resolved measurements, we find fast decay times for exciton (∼600 ps) and biexciton (∼300 ps). We demonstrate triggered single-photon emission (g{sup (2)}(0)=0.08) as well as cascaded emission from the biexciton decay. Our results suggest that these quantum dots can compete with their counterparts grown by state-of-the-art molecular beam epitaxy.

Styrene-butadiene-styrene copolymer compatibilized carbon black/polypropylene/polystyrene composites with tunable morphology, electrical conduction and rheological stabilities.

PubMed

Song, Yihu; Xu, Chunfeng; Zheng, Qiang

2014-04-21

We report a facile kinetic strategy in combination with styrene-butadiene-styrene (SBS) copolymer compatibilizers for preparing carbon black (CB) filled immiscible polypropylene (PP)/polystyrene (PS) (1/1) blends with finely tuned morphologies and show the important role of location and migration of CB nanoparticles in determining the electrical conductivity and rheological behaviour of the composites. A novel method of mixing a SBS/CB (5/3) masterbatch with the polymers allowed producing composites with CB aggregates dispersed partially in the unfavorable PP phase and partially in the PP side of the interface to exhibit diverse phase connectivity and electrical conductivity depending on the compounding sequences. A cocontinuous morphology with CB enrichment along the interface was formed in the composite prepared by mixing the SBS/CB masterbatch with the premixed PP/PS blend, giving rise to a highest electrical conductivity and dynamic moduli at low frequencies. On the other hand, mixing the masterbatch with one and then with another polymer yielded droplet (PS)-in-matrix (filled PP) composites. The composites underwent phase coalescence and CB redistribution accompanied by marked dynamic electrical conduction and modulus percolations as a function of time during thermal annealing at 180 °C. The composites with the initial droplet-in-matrix morphology progressed anomalously into the cocontinuous morphology, reflecting a common mechanism being fairly nonspecific for understanding the processing of filled multicomponent composites with tailored performances of general concern.

Graphene-coated polystyrene-divinylbenzene dispersive solid-phase extraction coupled with supercritical fluid chromatography for the rapid determination of 10 allergenic disperse dyes in industrial wastewater samples.

PubMed

Lou, Chaoyan; Wu, Can; Zhang, Kai; Guo, Dandan; Jiang, Lei; Lu, Yang; Zhu, Yan

2018-05-18

Allergenic disperse dyes are a group of environmental contaminants, which are toxic and mutagenic to human beings. In this work, a method of dispersive solid-phase extraction (d-SPE) using graphene-coated polystyrene-divinylbenzene (G@PS-DVB) microspheres coupled with supercritical fluid chromatography (SFC) was proposed for the rapid determination of 10 allergenic disperse dyes in industrial wastewater samples. G@PS-DVB microspheres were synthesized by coating graphene (G) sheets onto polystyrene-divinylbenzene (PS-DVB) polymers. Such novel sorbents were employed in d-SPE for the purification and concentration of allergenic disperse dyes in wastewater samples prior to the determination by SFC with UV detection. To achieve the maximum extraction efficiency for the target dyes, several parameters influencing d-SPE process such as sorbent dosage, extraction time, desorption conditions were investigated. SFC conditions including stationary phase, modifier composition and percentage, column temperature, backpressure and flow rate were optimized to well separate the allergenic disperse dyes. Under the optimum conditions, satisfactory linear relationship (R ≥ 0.9989) was observed with the concentration of dyes ranging from 0.02 to 10.0 μg/mL. The limits of detection (LOD, S/N = 3) for the ten dyes were in the range of 1.1-15.6 ng/mL. Recoveries for the spiked samples were between 89.1% and 99.7% with relative standard deviations (RSD) lower than 10.5% in all cases. The proposed method is time-saving, green, precise and repeatable for the analysis of the target dyes. Furthermore, the application of G@PS-DVB based d-SPE process can be potentially expanded to isolate and concentrate other aromatic compounds in various matrices and supercritical fluid chromatography methodology featuring rapidity, accuracy and green will be an ideal candidate for the analysis of these compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

Nanostructure size determination in p-type porous silicon by the use of transmission electron diffraction image processing

NASA Astrophysics Data System (ADS)

Ramirez-Porras, A.

2005-06-01

The structure of p-type porous silicon (PS) has been investigated by the use of transmission electron diffraction (TED) microscopy and image processing. The results suggest the presence of well oriented crystalline phases and polycrystalline phases characterized by random orientation. These phases are believed to be formed by spheres with a mean diameter of 4.3 nm and a standard deviation of 1.3 nm.

Wafer Scale Fabrication of Dense and High Aspect Ratio Sub-50 nm Nanopillars from Phase Separation of Cross-Linkable Polysiloxane/Polystyrene Blend.

PubMed

Li, Yang; Hao, Yuli; Huang, Chunyu; Chen, Xingyao; Chen, Xinyu; Cui, Yushuang; Yuan, Changsheng; Qiu, Kai; Ge, Haixiong; Chen, Yanfeng

2017-04-19

We demonstrated a simple and effective approach to fabricate dense and high aspect ratio sub-50 nm pillars based on phase separation of a polymer blend composed of a cross-linkable polysiloxane and polystyrene (PS). In order to obtain the phase-separated domains with nanoscale size, a liquid prepolymer of cross-linkable polysiloxane was employed as one moiety for increasing the miscibility of the polymer blend. After phase separation via spin-coating, the dispersed domains of liquid polysiloxane with sub-50 nm size could be solidified by UV exposure. The solidified polysiloxane domains took the role of etching mask for formation of high aspect ratio nanopillars by O 2 reactive ion etching (RIE). The aspect ratio of the nanopillars could be further amplified by introduction of a polymer transfer layer underneath the polymer blend film. The effects of spin speeds, the weight ratio of the polysiloxane/PS blend, and the concentration of polysiloxane/PS blend in toluene on the characters of the nanopillars were investigated. The gold-coated nanopillar arrays exhibited a high Raman scattering enhancement factor in the range of 10 8 -10 9 with high uniformity across over the wafer scale sample. A superhydrophobic surface could be realized by coating a self-assembled monolayers (SAM) of fluoroalkyltrichlorosilane on the nanopillar arrays. Sub-50 nm silicon nanowires (SiNWs) with high aspect ratio of about 1000 were achieved by using the nanopillars as etching mask through a metal-assisted chemical etching process. They showed an ultralow reflectance of approximately 0.1% for wavelengths ranging from 200 to 800 nm.

Beyond PSInSAR: the SQUEESAR Approach

NASA Astrophysics Data System (ADS)

Ferretti, A.; Novali, F.; Fumagalli, A.; Prati, C.; Rocca, F.; Rucci, A.

2009-12-01

After a decade since the first results on ERS data, Permanent Scatterer (PS) InSAR has become an operational technology for detecting and monitoring slow surface deformation phenomena such as subsidence and uplift, landslides, seismic fault creeping, volcanic inflation, etc. Processing procedures have been continuously updated, but the core of the algorithm has not been changed significantly. As well known, in PSInSAR, the main target is the identification of individual pixels that exhibit a “PS behavior”, i.e. they are only slightly affected by both temporal and geometrical decorrelation. Typically, these scatterers correspond to man-made objects, but PS have been identified also in non-urban areas, where exposed rocks or outcrops can indeed create good radar benchmarks and enable high-quality displacement measurements. Contrary to interferogram stacking techniques, PS analyses are carried out on a pixel-by-pixel basis, with no filtering of the interferograms, in order to preserve phase values from possible incoherent clutter surrounding good radar targets. In fact, any filtering process implies a spatial smoothing of the data that could compromise - rather than improve - phase coherence, at least for isolated PS. Although the PS approach usually allows one to retrieve high quality deformation measurements on a sparse grid of good radar targets, in some datasets it is quite evident how the number of pixels where some information can be extracted could be significantly increased by relaxing the hypothesis on target coherence and searching for pixels where the coherence level is high enough at least in some interferograms of the data-stack, not necessarily all. The idea of computing a “coherence matrix” for each pixel of the area of interest have been already proposed in previous papers, together with a statistical estimation of some physical parameters of interest (e.g. the average displacement rate) based on the covariance matrix. In past publications, however, it was not highlighted how a reliable estimation of the coherence matrix can be carried out on distributed scatterers only, characterized by a sufficient number of looks, sharing the same statistics of the reflectivity values. In this paper, we propose how to estimate reliable coherence values by properly selecting the statistical population used in the estimation. In standard PSInSAR, the so-called amplitude stability index is used as a proxy for temporal phase coherence, here we expand the concept and we show how local amplitude statistics can be successfully exploited to detect distributed scatterers, rather than individual pixels, where reliable statistical parameters can be extracted. As a byproduct of carefully estimating coherence values, we get despeckled amplitude images and filtered interferograms. Coherence matrixes and distributed scatterers, apart from the well-known PS, then become invaluable sources of information that can be “squeezed” to estimate any InSAR parameter of interest (the SqueeSAR concept). Preliminary results on real datasets will be shown using both C-band and X-band SAR data.

Electrorheological effect and electro-optical properties of side-on liquid crystalline polysiloxane in a nematic solvent.

PubMed

Kaneko, Kosuke; Oto, Kodai; Kawai, Toshiaki; Choi, Hyunseok; Kikuchi, Hirotsugu; Nakamura, Naotake

2013-08-26

The electrorheological (ER) effect and the electro-optical properties of a ''side-on'' liquid crystalline polysiloxane (PS) are investigated. A large ER effect is observed and the response to the shear stress of neat PS in the nematic phase is shown to be affected by the shear rate. PS is also mixed with a low-molar nematic liquid crystal (5CB) in order to improve the response behavior to the applied electric field. The rheological properties of such mixtures are highly dependent on the concentration of 5CB. The composites respond faster to the applied electric field and have improved electro-optical properties. This study offers a new perspective on the development of liquid crystal materials for the ER effect. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of porous carbon nanofiber with bamboo-like carbon nanofiber branches by one-step carbonization process

NASA Astrophysics Data System (ADS)

Yoo, Seung Hwa; Joh, Han-Ik; Lee, Sungho

2017-04-01

Porous carbon nanofibers (PCNFs) with CNF branches (PCNF/bCNF) were synthesized by a simple heat treatment method. Conventional methods to synthesize this unique structure usually follow a typical route, which consists of CNF preparation, catalyst deposition, and secondary CNF growth. In contrast, our method utilized a one-step carbonization process of polymer nanofibers, which were electrospun from a one-pot solution consisted of polyacrylonitrile, polystyrene (PS), and iron acetylacetonate. Various structures of PCNF/CNF were synthesized by changing the solution composition and molecular weight of PS. It was verified that the content and molecular weight of PS were critical for the growth of catalyst particles and subsequent growth of CNF branches. The morphology, phase of catalyst, and carbon structure of PCNF/bCNF were analyzed at different temperature steps during carbonization. It was found that pores were generated by the evaporation of PS and the catalyst particles were formed on the surface of PCNF at 700 °C. The gases originated from the evaporation of PS acted as a carbon source for the growth of CNF branches that started at 900 °C. Finally, when the carbonization process was finished at 1200 °C, uniform and abundant CNF branches were formed on the surface of PCNF.

Thrust noise minimization in long-term laser ablation of propellant material in the nanosecond and picosecond regime

NASA Astrophysics Data System (ADS)

Lorbeer, Raoul-Amadeus; Scharring, Stefan; Karg, Stephanie; Pastow, Jan; Pastuschka, Lisa; Förster, Daniel Johannes; Eckel, Hans-Albert

2017-01-01

The avoidance of any moving parts in a microthruster exhibits a great potential for low-noise thrust generation in the micronewton range. This is required, e.g., for scientific missions that need attitude and orbit control systems with exquisite precision. Laser ablation propulsion offers the opportunity of permanent inertia-free, electro-optical delivery of laser energy to access the propellant entirely without moving it. New propellant is accessed by ablating the previous surface in layers, essentially damaging the surface with a laser over and over again. The resulting surface properties for different fluences and scanning patterns were investigated for multiple layers of aluminum, copper, and gold. The pulse-length-specific issues of various ablation mechanisms such as vaporization, spallation, and phase explosion are accounted for by the use of a 10-ps laser system and a 500-ps laser system. We show that the surface roughness produced with 500-ps laser pulses is approximately twice the surface roughness generated by using 10-ps laser pulses. Furthermore, with 500-ps pulses, the surface roughness shows low dependency on the fluence for carefully chosen scanning parameters. Therefore, we conclude that laser pulse duration differences in the picosecond and nanosecond regimes will not necessarily alter surface roughness properties.

Remineralization of in vitro dental caries assessed with polarization-sensitive optical coherence tomography

NASA Astrophysics Data System (ADS)

Jones, Robert S.; Darling, Cynthia L.; Featherstone, John D. B.; Fried, Daniel

2006-01-01

Polarization-sensitive optical coherence tomography (PS-OCT) is potentially useful for imaging the nonsurgical remineralization of dental enamel. This study uses an all-fiber-based PS-OCT system operating at 1310 nm to image demineralized and fluoride-enhanced remineralized artificial lesions. PS-OCT images of lesions before and after remineralization are compared with the relative mineral loss ΔZ (%vol×µm), obtained from high resolution digital microradiography (DM), and chemical composition changes by infrared spectroscopy. Severe early artificial caries show a significant increase in perpendicular-axis integrated reflectivity after remineralization. After sectioning the samples, DM demonstrates that the lesions remineralized with new mineral and the lesion surface zone show significant restoration of mineral volume. PS-OCT and DM both do not show a major change in lesion depth. For less severe artificial caries, the perpendicular-axis image resolves the scattering and depolarization of an outer growth layer after remineralization. This outer layer has a mineral volume close to that of sound enamel, and spectroscopic analysis indicates that the layer is a highly crystalline phase of apatite, without carbonate substitutions that increase the solubility of sound enamel. This study determines that PS-OCT can image the effects of fluoride-enhanced remineralization of mild and severe early artificial in vitro caries.

Spin conversion of positronium in NiO/Al2O3 catalysts observed by coincidence Doppler broadening technique

NASA Astrophysics Data System (ADS)

Zhang, H. J.; Chen, Z. Q.; Wang, S. J.; Kawasuso, A.; Morishita, N.

2010-07-01

High-purity NiO/Al2O3 catalysts were prepared by mixing NiO and γ-Al2O3 nanopowders. X-ray diffraction patterns were measured to characterize the grain size and crystalline phase of the nanopowders. Positron-annihilation spectroscopy was used to study the microstructure and surface properties of the pores inside the NiO/Al2O3 catalysts. The positron lifetime spectrum comprises two short and two long lifetime components. The two long lifetimes τ3 and τ4 correspond to ortho-positronium (o-Ps) annihilated in microvoids and large pores, respectively. With increasing NiO content in the NiO/Al2O3 catalysts, both τ4 and its intensity I4 show continuous decrease. Meanwhile, the para-positronium (p-Ps) intensity, obtained from coincidence Doppler broadening spectra, increases gradually with NiO content. The different variation in o-Ps and p-Ps intensity suggests the ortho-para conversion of positronium in NiO/Al2O3 catalysts. X-ray photoelectron spectroscopy shows that Ni mainly exists in the form of NiO. The electron-spin-resonance measurements reveal that the ortho-para conversion of Ps is induced by the unpaired electrons of the paramagnetic centers of NiO.

Long-term immunogenicity and safety after a single dose of the quadrivalent meningococcal serogroups A, C, W, and Y tetanus toxoid conjugate vaccine in adolescents and adults: 5-year follow-up of an open, randomized trial.

PubMed

Borja-Tabora, Charissa Fay Corazon; Montalban, Cecilia; Memish, Ziad A; Boutriau, Dominique; Kolhe, Devayani; Miller, Jacqueline M; Van der Wielen, Marie

2015-10-06

Long-term protection against meningococcal disease is associated with persistence of post-vaccination antibodies at protective levels. We evaluated the bactericidal antibody persistence and safety of the quadrivalent meningococcal serogroups A, C, W and Y tetanus-toxoid conjugate vaccine (MenACWY-TT) and the meningococcal polysaccharide serogroups A, C, W, and Y vaccine (MenACWY-PS) up to 5 years post-vaccination. This phase IIb, open, randomized, controlled study conducted in the Philippines and Saudi Arabia consisted of a vaccination phase and a long-term persistence phase. Healthy adolescents and adults aged 11-55 years were randomized (3:1) to receive a single dose of MenACWY-TT (ACWY-TT group) or MenACWY-PS (Men-PS group). Primary and persistence results up to 3 years post-vaccination have been previously reported. Antibody responses against meningococcal serogroups A, C, W, and Y were assessed by a serum bactericidal antibody assay using rabbit complement (rSBA, cut-off titers 1:8 and 1:128) at Year 4 and Year 5 post-vaccination. Vaccine-related serious adverse events (SAEs) and cases of meningococcal disease were assessed up to Year 5. Of the 500 vaccinated participants, 404 returned for the Year 5 study visit (Total Cohort Year 5). For the Total Cohort Year 5, 71.6-90.0 and 64.9-86.3 % of MenACWY-TT recipients had rSBA titers ≥1:8 and ≥1:128, respectively, compared to 24.8-74.3 and 21.0-68.6 % of MenACWY-PS recipients. The rSBA geometric mean titers (GMTs) remained above the pre-vaccination levels in both treatment groups. Exploratory analyses suggested that both rSBA GMTs as well as the percentages of participants with rSBA titers above the cut-offs were higher in the ACWY-TT than in the Men-PS group for serogroups A, W and Y, with no apparent difference for MenC. No SAEs related to vaccination or cases of meningococcal disease were reported up to Year 5. These results suggest that a single dose of MenACWY-TT could protect at least 72 % of vaccinated adolescents and adults against meningococcal disease at least 5 years post-vaccination. ClinicalTrials.gov NCT00356369.

Improvements in productivity at paid work and within the household, and increased participation in daily activities after 24 weeks of certolizumab pegol treatment of patients with psoriatic arthritis: results of a phase 3 double-blind randomised placebo-controlled study

PubMed Central

Kavanaugh, A; Gladman, D; van der Heijde, D; Purcaru, O; Mease, P

2015-01-01

Objectives To evaluate the effect of certolizumab pegol (CZP) on productivity outside and within the home, and on participation in family, social and leisure activities in adult patients with psoriatic arthritis (PsA). Methods RAPID-PsA (NCT01087788) is a phase 3, double-blind, placebo-controlled trial. 409 patients with active PsA were randomised 1:1:1 to placebo, CZP 200 mg every 2 weeks (Q2W) or CZP 400 mg every 4 weeks (Q4W). The arthritis-specific Work Productivity Survey (WPS) assessed the impact of PsA on paid work and household productivity, and participation in social activities during the preceding month. WPS responses were compared between treatment arms using a non-parametric bootstrap-t method. Results At baseline, 56.6%, 60.1% and 61.5% of placebo, CZP 200 mg Q2W and CZP 400 mg Q4W patients were employed. By week 24, employed CZP patients reported an average of 1.0–1.8 and 3.0–3.9 fewer days of absenteeism and presenteeism, respectively, per month compared with 1.0 and 0.3 fewer days for placebo patients (p<0.05). Within the home, by week 24, CZP patients reported an average of 3.0–3.5 household work days gained per month versus 1.0 day for placebo (p<0.05). CZP patients also reported fewer days with reduced household productivity or days lost for participation in family, social and leisure activities. Improvements with CZP were seen as early as week 4 and continued to week 24. Conclusions CZP treatment significantly improved productivity at paid work and within the home, and resulted in greater participation in social activities for PsA patients. Trial registration number NCT01087788. PMID:24942382

Solid-Phase Fe Speciation along the Vertical Redox Gradients in Floodplains using XAS and Mössbauer Spectroscopies.

PubMed

Chen, Chunmei; Kukkadapu, Ravi K; Lazareva, Olesya; Sparks, Donald L

2017-07-18

Properties of Fe minerals are poorly understood in natural soils and sediments with variable redox conditions. In this study, we combined 57 Fe Mössbauer and Fe K-edge X-ray absorption spectroscopic (XAS) techniques to assess solid-phase Fe speciation along the vertical redox gradients of floodplains, which exhibited a succession of oxic, anoxic, and suboxic-oxic zones with increasing depth along the vertical profiles. The incised stream channel is bounded on the east by a narrow floodplain and a steep hillslope, and on the west by a broad floodplain. In the eastern floodplain, the anoxic conditions at the intermediate horizon (55-80 cm) coincided with lower Fe(III)-oxides (particularly ferrihydrite), in concurrence with a greater reduction of phyllosilicates(PS)-Fe(III) to PS-Fe(II), relative to the oxic near-surface and sandy gravel layers. In addition, the anoxic conditions in the eastern floodplain coincided with increased crystallinity of goethite, relative to the oxic layers. In the most reduced intermediate sediments at 80-120 cm of the western floodplain, no Fe(III)-oxides were detected, concurrent with the greatest PS-Fe(III) reduction (PS-Fe(II)/Fe(III) ratio ≈ 1.2 (Mössbauer) or 0.8 (XAS)). In both oxic near-surface horizon and oxic-suboxic gravel aquifers beneath the soil horizons, Fe(III)-oxides were mainly present as ferrihydrite with a much less amount of goethite, which preferentially occurred as nanogoethite or Al/Si-substituted goethite. Ferrihydrite with varying crystallinity or impurities such as organic matter, Al or Si, persisted under suboxic-oxic conditions in the floodplain. This study indicates that vertical redox gradients exert a major control on the quantity and speciation of Fe(III) oxides as well as the oxidation state of structural Fe in PS, which could significantly affect nutrient cycling and carbon (de)stabilization.

Physical and material properties of an emulsion-based lipstick produced via a continuous process.

PubMed

Beri, A; Pichot, R; Norton, I T

2014-04-01

Water-in-oil emulsions in lipsticks could have the potential to improve moisturizing properties and deliver hydrophilic molecules to the lips. The aim of this work was to investigate the effect of a continuous process (scraped surface heat exchanger (SSHE) and pin stirrer (PS)) on the physical and material properties of an emulsion-based lipstick by altering the processing conditions of both the SSHE and PS. Emulsion formation was achieved using a SSHE and PS. Emulsions were analysed using nuclear magnetic resonance restricted diffusion (droplet size), texture analysis and rheology (mechanical properties). Results showed that a higher impeller rotational velocity (IRV) (1500 r.p.m.) and a lower exit temperature (52°C) produce the smallest droplets (~ 4 μm), due to greater disruptive forces and a higher viscosity of the continuous phase. The addition of a PS reduces the droplet size (14-6 μm) if the SSHE has a low IRV (500 r.p.m.), due to greater droplet disruption as the emulsion passes through the PS unit. Results also show that if the jacket temperature of a SSHE is 65°C, so that crystallization occurs in both process and post-production, droplets can be integrated into the network resulting in a stiffer wax network (G' - 0.12, in comparison to 0.02 MPa). This is due to small crystals creating a shell around water droplets which can form connections with the continuous network forming a structured network. The addition of a pin stirrer can disrupt a formed network reducing the stiffness of the emulsion (0.3-0.05 MPa). This work suggests the potential use of a continuous process in producing an emulsion-based lipstick, particularly when wax crystals are produced in the process. Future work should consider the moisturizing or lubricating properties of wax continuous emulsions and the release of hydrophilic compounds from the aqueous phase.

Additive effects of plant sterols supplementation in addition to different lipid-lowering regimens.

PubMed

Malina, Daniela M T; Fonseca, Francisco A; Barbosa, Sílvio A; Kasmas, Soraia H; Machado, Valéria A; França, Carolina N; Borges, Ney C; Moreno, Ronilson A; Izar, Maria C

2015-01-01

Plant sterol (PS) supplementation has been widely used alone or combined with lipid-lowering therapies (LLTs) to reduce low-density lipoprotein (LDL) cholesterol. The effects of PS added to high-intensity LLT are less reported, especially regarding the effects on cholesterol synthesis and absorption. A prospective, randomized, open-label study, with parallel arms and blinded end points was designed to evaluate the effects of addition of PS to LLT on LDL cholesterol, markers of cholesterol synthesis, and absorption. Eighty-six patients of both genders were submitted to a 4-wk run-in period with atorvastatin 10 mg (baseline). Following, subjects received atorvastatin 40 mg, ezetimibe 10 mg, or combination of both drugs for another 4-wk period (phase I). In phase II, capsules containing 2.0 g of PSs were added to previous assigned treatments for 4 wk. Lipids, apolipoproteins, plasma campesterol, β-sitosterol, and desmosterol levels were assayed at all time points. Within and between-group analyses were performed. Compared with baseline, atorvastatin 40 mg reduced total and LDL cholesterol (3% and 22%, respectively, P < .05), increased β-sitosterol, campesterol/cholesterol, and β-sitosterol/cholesterol ratios (39%, 47%, and 32%, respectively, P < .05); ezetimibe 10 mg reduced campesterol and campesterol/cholesterol ratio (67% and 70%, respectively, P < .05), and the combined therapy decreased total and LDL cholesterol (22% and 38%, respectively, P < .05), campesterol, β-sitosterol, and campesterol/cholesterol ratio (54%, 40%, and 27%, P < .05). Addition of PS further reduced total and LDL cholesterol by ∼ 7.7 and 6.5%, respectively, in the atorvastatin therapy group and 5.0 and 4.0% in the combined therapy group (P < .05, for all), with no further effects in absorption or synthesis markers. PS added to LLT can further improve lipid profile, without additional effects on intestinal sterol absorption or synthesis. Copyright © 2015 National Lipid Association. Published by Elsevier Inc. All rights reserved.

Geometry of phase-separated domains in phospholipid bilayers by diffraction-contrast electron microscopy.

PubMed Central

Hui, S W

1981-01-01

The sizes and shapes of solidus (gel) phase domains in the hydrated molecular bilayers of dilauroylphosphatidylcholine/dipalmitoylphasphatidylcholine (DLPC/DPPC) (1:1) and phosphatidylserine (PS)/DPPC (1:2) are visualized directly by low dose diffraction-contrast electron microscopy. The temperature and humidity of the bilayers are controlled by an environmental chamber set in an electron microscope. The contrast between crystalline domains is enhanced by electron optical filtering of the diffraction patterns of the bilayers. The domains are seen as a patchwork in the plane of the bilayer, with an average width of 0.2-0.5 micrometer. The percentage of solidus area measured from diffraction-contrast micrographs at various temperatures agrees in general with those depicted by known phase diagrams. The shape and size of the domains resemble those seen by freeze-fracture in multilamellar vesicles. Temperature-related changes in domain size and in phase boundary per unit area are more pronounced in the less miscible DLPC/DPPC mixture. No significant change in these geometric parameters with temperature is found in the PS/DPPC mixture. Mapping domains by their molecular diffraction signals not only verifies the existance of areas of different molecular packing during phase separation but also provides a quantitative measurement of structural boundaries and defects in lipid bilayers. Images FIGURE 1 FIGURE 3 FIGURE 6 PMID:6894707

Assembly of acid-functionalized single-walled carbon nanotubes at oil/water interfaces.

PubMed

Feng, Tao; Hoagland, David A; Russell, Thomas P

2014-02-04

The efficient segregation of water-soluble, acid-functionalized, single-walled carbon nanotubes (SWCNTs) at the oil/water interface was induced by dissolving low-molecular-weight amine-terminated polystyrene (PS-NH2) in the oil phase. Salt-bridge interactions between carboxylic acid groups of SWCNTs and amine groups of PS drove the assembly of SWCNTs at the interface, monitored by pendant drop tensiometry and laser scanning confocal microscopy. The impact of PS end-group functionality, PS and SWCNT concentrations, and the degree of SWCNT acid modification on the interfacial activity was assessed, and a sharp drop in interfacial tension was observed above a critical SWCNT concentration. Interfacial tensions were low enough to support stable oil/water emulsions. Further experiments, including potentiometric titrations and the replacement of SWCNTs by other carboxyl-containing species, demonstrated that the interfacial tension drop reflects the loss of SWCNT charge as the pH falls near/below the intrinsic carboxyl dissociation constant; species lacking multivalent carboxylic acid groups are inactive. The trapped SWCNTs appear to be neither ordered nor oriented.

Conversion of "Waste Plastic" into Photocatalytic Nanofoams for Environmental Remediation.

PubMed

de Assis, Geovania C; Skovroinski, Euzébio; Leite, Valderi D; Rodrigues, Marcelo O; Galembeck, André; Alves, Mary C F; Eastoe, Julian; de Oliveira, Rodrigo J

2018-03-07

Plastic debris is a major environmental concern, and to find effective ways to reuse polystyrene (PS) presents major challenges. Here, it is demonstrated that polystyrene foams impregnated with SnO 2 are easily generated from plastic debris and can be applied to photocatalytic degradation of dyes. SnO 2 nanoparticles were synthesized by a polymeric precursor method, yielding specific surface areas of 15 m 2 /g after heat treatment to 700 °C. Crystallinity, size, and shape of the SnO 2 particles were assessed by X-ray diffraction (XRD) and transmission electron microscopy (TEM), demonstrating the preparation of crystalline spherical nanoparticles with sizes around 20 nm. When incorporated into PS foams, which were generated using a thermally induced phase separation (TIPS) process, the specific surface area increased to 48 m 2 /g. These PS/SnO 2 nanofoams showed very good efficiency for photodegradation of rhodamine B, under UV irradiation, achieving up to 98.2% removal. In addition the PS/SnO 2 nanofoams are shown to retain photocatalytic activity for up to five reuse cycles.

What can platinum offer yet in the treatment of PS2 NSCLC patients? A systematic review and meta-analysis.

PubMed

Bronte, Giuseppe; Rolfo, Christian; Passiglia, Francesco; Rizzo, Sergio; Gil-Bazo, Ignacio; Fiorentino, Eugenio; Cajozzo, Massimo; Van Meerbeeck, Jan P; Lequaglie, Cosimo; Santini, Daniele; Pauwels, Patrick; Russo, Antonio

2015-09-01

Randomized phase III trials showed interesting, but conflicting results, regarding the treatment of NSCLC, PS2 population. This meta-analysis aims to review all randomized trials comparing platinum-based doublets and single-agents in NSCLC PS2 patients. Data from all published randomized trials, comparing efficacy and safety of platinum-based doublets to single agents in untreated NSCLC, PS2 patients, were collected. Pooled ORs were calculated for the 1-year Survival-Rate (1y-SR), Overall Response Rate (ORR), and grade 3-4 (G3-4) hematologic toxicities. Six eligible trials (741 patients) were selected. Pooled analysis showed a significant improvement in ORR (OR: 3.243; 95% CI: 1.883-5.583) and 1y-SR (OR: 1.743; 95% CI: 1.203-2.525) in favor of platinum-based doublets. G3-4 hematological toxicities were also more frequent in this group. This meta-analysis suggests that platinum-combination regimens are superior to singleagent both in terms of ORR and survival-rate with increase of severe hematological toxicities. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

In vivo optical microscopy of peripheral nerve myelination with polarization sensitive-optical coherence tomography

PubMed Central

Henry, Francis P.; Wang, Yan; Rodriguez, Carissa L. R.; Randolph, Mark A.; Rust, Esther A. Z.; Winograd, Jonathan M.; de Boer, Johannes F.; Park, B. Hyle

2015-01-01

Abstract. Assessing nerve integrity and myelination after injury is necessary to provide insight for treatment strategies aimed at restoring neuromuscular function. Currently, this is largely done with electrical analysis, which lacks direct quantitative information. In vivo optical imaging with sufficient imaging depth and resolution could be used to assess the nerve microarchitecture. In this study, we examine the use of polarization sensitive-optical coherence tomography (PS-OCT) to quantitatively assess the sciatic nerve microenvironment through measurements of birefringence after applying a nerve crush injury in a rat model. Initial loss of function and subsequent recovery were demonstrated by calculating the sciatic function index (SFI). We found that the PS-OCT phase retardation slope, which is proportional to birefringence, increased monotonically with the SFI. Additionally, histomorphometric analysis of the myelin thickness and g-ratio shows that the PS-OCT slope is a good indicator of myelin health and recovery after injury. These results demonstrate that PS-OCT is capable of providing nondestructive and quantitative assessment of nerve health after injury and shows promise for continued use both clinically and experimentally in neuroscience. PMID:25858593

In vivo optical microscopy of peripheral nerve myelination with polarization sensitive-optical coherence tomography.

PubMed

Henry, Francis P; Wang, Yan; Rodriguez, Carissa L R; Randolph, Mark A; Rust, Esther A Z; Winograd, Jonathan M; de Boer, Johannes F; Park, B Hyle

2015-04-01

Assessing nerve integrity and myelination after injury is necessary to provide insight for treatment strategies aimed at restoring neuromuscular function. Currently, this is largely done with electrical analysis, which lacks direct quantitative information. In vivo optical imaging with sufficient imaging depth and resolution could be used to assess the nerve microarchitecture. In this study, we examine the use of polarization sensitive-optical coherence tomography (PS-OCT) to quantitatively assess the sciatic nerve microenvironment through measurements of birefringence after applying a nerve crush injury in a rat model. Initial loss of function and subsequent recovery were demonstrated by calculating the sciatic function index (SFI). We found that the PS-OCT phase retardation slope, which is proportional to birefringence, increased monotonically with the SFI. Additionally, histomorphometric analysis of the myelin thickness and g-ratio shows that the PS-OCT slope is a good indicator of myelin health and recovery after injury. These results demonstrate that PS-OCT is capable of providing nondestructive and quantitative assessment of nerve health after injury and shows promise for continued use both clinically and experimentally in neuroscience.

Hypertension, cerebrovascular impairment, and cognitive decline in aged AβPP/PS1 mice.

PubMed

Wiesmann, Maximilian; Zerbi, Valerio; Jansen, Diane; Lütjohann, Dieter; Veltien, Andor; Heerschap, Arend; Kiliaan, Amanda J

2017-01-01

Cardiovascular risk factors, especially hypertension, are also major risk factors for Alzheimer's disease (AD). To elucidate the underlying vascular origin of neurodegenerative processes in AD, we investigated the relation between systolic blood pressure (SBP) cerebral blood flow (CBF) and vasoreactivity with brain structure and function in a 16-18 months old double transgenic AβPP swe /PS1 dE9 (AβPP/PS1) mouse model for AD. These aging AβPP/PS1 mice showed an increased SBP linked to a declined regional CBF. Furthermore, using advanced MRI techniques, decline of functional and structural connectivity was revealed in the AD-like mice coupled to impaired cognition, increased locomotor activity, and anxiety-related behavior. Post mortem analyses demonstrated also increased neuroinflammation, and both decreased synaptogenesis and neurogenesis in the AβPP/PS1 mice. Additionally, deviant levels of fatty acids and sterols were present in the brain tissue of the AβPP/PS1 mice indicating maladapted brain fatty acid metabolism. Our findings suggest a link between increased SBP, decreased cerebral hemodynamics and connectivity in an AD mouse model during aging, leading to behavioral and cognitive impairments. As these results mirror the complex clinical symptomatology in the prodromal phase of AD, we suggest that this AD-like murine model could be used to investigate prevention and treatment strategies for early AD patients. Moreover, this study helps to develop more efficient therapies and diagnostics for this very early stage of AD.

Simultaneous Ka-Band Site Characterization: Goldstone, CA, White Sands, NM, and Guam, USA

NASA Technical Reports Server (NTRS)

Acosta, Roberto; Morse, Jacquelynne; Zemba, Michael; Nessel, James; Morabito, David; Caroglanian, Armen

2011-01-01

To statistically characterize atmospheric effects on Ka-band links at NASA operational sites, NASA has constructed site test interferometers (STI s) which directly measure the tropospheric phase stability and rain attenuation. These instruments observe an unmodulated beacon signal broadcast from a geostationary satellite (e.g., Anik F2) and measure the phase difference between the signals received by the two antennas and its signal attenuation. Three STI s have been deployed so far: the first one at the NASA Deep Space Network Tracking Complex in Goldstone, California (May 2007); the second at the NASA White Sands Complex, in Las Cruses, New Mexico (February 2009); and the third at the NASA Tracking and Data Relay Satellite (TDRS) Remote Ground Terminal (GRGT) complex in Guam (May 2010). Two station-years of simultaneous atmospheric phase fluctuation data have been collected at Goldstone and White Sands, while one year of data has been collected in Guam. With identical instruments operating simultaneously, we can directly compare the phase stability and rain attenuation at the three sites. Phase stability is analyzed statistically in terms of the root-mean-square (rms) of the tropospheric induced time delay fluctuations over 10 minute blocks. For two years, the time delay fluctuations at the DSN site in Goldstone, CA, have been better than 2.5 picoseconds (ps) for 90% of the time (with reference to zenith), meanwhile at the White Sands, New Mexico site, the time delay fluctuations have been better than 2.2 ps with reference to zenith) for 90% of time. For Guam, the time delay fluctuations have been better than 12 ps (reference to zenith) at 90% of the time, the higher fluctuations are as expected from a high humidity tropical rain zone. This type of data analysis, as well as many other site quality characteristics (e.g., rain attenuation, infrastructure, etc.) will be used to determine the suitability of all the sites for NASA s future communication services at Ka-band.

A low jitter all - digital phase - locked loop in 180 nm CMOS technology

NASA Astrophysics Data System (ADS)

Shumkin, O. V.; Butuzov, V. A.; Normanov, D. D.; Ivanov, P. Yu

2016-02-01

An all-digital phase locked loop (ADPLL) was implemented in 180 nm CMOS technology. The proposed ADPLL uses a digitally controlled oscillator to achieve 3 ps resolution. The pure digital phase locked loop is attractive because it is less sensitive to noise and operating conditions than its analog counterpart. The proposed ADPLL can be easily applied to different process as a soft IP block, making it very suitable for system-on-chip applications.

Water-in-oil Pickering emulsions stabilized by stearoylated microcrystalline cellulose.

PubMed

Pang, Bo; Liu, Huan; Liu, Peiwen; Peng, Xinwen; Zhang, Kai

2018-03-01

Hydrophobic particles with static water contact angles larger than 90° are more like to stabilize W/O Pickering emulsions. In particular, high internal phase Pickering emulsions (HIPEs) are of great interest for diverse applications. However, W/O HIPEs have rarely been realized using sustainable biopolymers. Herein, we used stearoylated microcrystalline cellulose (SMCC) to stabilize W/O Pickering emulsions and especially, W/O HIPEs. Moreover, these W/O HIPEs can be further used as platforms for the preparation of porous materials, such as porous foams. Stearoylated microcrystalline cellulose (SMCC) was prepared by modifying MCC with stearoyl chloride under heterogeneous conditions. Using SMCC as emulsifiers, W/O medium and high internal phase Pickering emulsions (MIPEs and HIPEs) with various organic solvents as continuous phases were prepared using one-step and two-step methods, respectively. Polystyrene (PS) foams were prepared after polymerization of oil phase using HIPEs as templates and their oil/water separation capacity were studied. SMCC could efficiently stabilize W/O Pickering emulsions and HIPEs could only be prepared via the two-step method. The internal phase volume fraction of the SMCC-stabilized HIPEs reached as high as 89%. Diverse internal phase volume fractions led to distinct inner structures of foams with closed or open cells. These macroporous polystyrene (PS) foams demonstrated great potential for the effective absorption of organic solvents from underwater. Copyright © 2017 Elsevier Inc. All rights reserved.

Metal Oxide Assisted Preparation of Core-Shell Beads with Dense Metal-Organic Framework Coatings for the Enhanced Extraction of Organic Pollutants.

PubMed

Del Rio, Mateo; Palomino Cabello, Carlos; Gonzalez, Veronica; Maya, Fernando; Parra, Jose B; Cerdà, Victor; Turnes Palomino, Gemma

2016-08-08

Dense and homogeneous metal-organic framework (MOF) coatings on functional bead surfaces are easily prepared by using intermediate sacrificial metal oxide coatings containing the metal precursor of the MOF. Polystyrene (PS) beads are coated with a ZnO layer to give ZnO@PS core-shell beads. The ZnO@PS beads are reactive in the presence of 2-methylimidazole to transform part of the ZnO coating into a porous zeolitic imidazolate framework-8 (ZIF-8) external shell positioned above the internal ZnO precursor shell. The obtained ZIF-8@ZnO@PS beads can be easily packed in column format for flow-through applications, such as the solid-phase extraction of trace priority-listed environmental pollutants. The prepared material shows an excellent permeance to flow when packed as a column to give high enrichment factors, facile regeneration, and excellent reusability for the extraction of the pollutant bisphenol A. It also shows an outstanding performance for the simultaneous enrichment of mixtures of endocrine disrupting chemicals (bisphenol A, 4-tert-octylphenol and 4-n-nonylphenol), facilitating their analysis when present at very low levels (<1 μg L(-1) ) in drinking waters. For the extraction of the pollutant bisphenol A, the prepared ZIF-8@ZnO@PS beads also show a superior extraction and preconcentration capacity to that of the PS beads used as precursors and the composite materials obtained by the direct growth of ZIF-8 on the surface of the PS beads in the absence of metal oxide intermediate coatings. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Epitope mapping and analysis of a growth-enhancing monoclonal antibody by limited tryptic digestion of porcine GH.

PubMed

Shieh, H M; Bass, R T; Wang, B S; Corbett, M J; Buckwalter, B L

1995-04-01

In this study, the epitope of a murine PS-7.6 monoclonal antibody (mAb) which was raised against the recombinant porcine GH (pGH) and subsequently shown to enhance the growth-promoting activity of pGH in a hypophysectomized rat model, was mapped by the limited tryptic digestion of pGH. A pGH fragment corresponding to amino acid residues 70-95 was separated by reverse-phase HPLC and also immunoprecipitated by PS-7.6 mAb. This fragment was found in an RIA to compete with radiolabelled pGH for the binding of PS-7.6 mAb in a dose-dependent fashion. Several peptides covering this potential epitope region of pGH(70-95) were synthesized and assayed by competitive RIA. The results suggested that pGH(75-90) was the optimal sequence recognized by PS-7.6 mAb. Sequential alanine substitution of each residue of pGH(75-90) revealed that the side chains of Leu76, Ile83 and Leu87 were critical for binding to PS-7.6 mAb. Other residues could be replaced by alanine without substantially altering the binding affinity. The region of amino acids 75-95 comprises the C-terminal end of the second helix of pGH and the repeating pattern of i and i + 3 (i + 7) of the critical amino acids appears consistent with PS-7.6 mAb binding to the hydrophobic side of the helix. The sequence and the helical structure of the epitope of PS-7.6 mAb provide the basis for designing the effective peptide vaccines to enhance the growth performance of animals.

Research on Methods of High Coherent Target Extraction in Urban Area Based on Psinsar Technology

NASA Astrophysics Data System (ADS)

Li, N.; Wu, J.

2018-04-01

PSInSAR technology has been widely applied in ground deformation monitoring. Accurate identification of Persistent Scatterers (PS) is key to the success of PSInSAR data processing. In this paper, the theoretic models and specific algorithms of PS point extraction methods are summarized and the characteristics and applicable conditions of each method, such as Coherence Coefficient Threshold method, Amplitude Threshold method, Dispersion of Amplitude method, Dispersion of Intensity method, are analyzed. Based on the merits and demerits of different methods, an improved method for PS point extraction in urban area is proposed, that uses simultaneously backscattering characteristic, amplitude and phase stability to find PS point in all pixels. Shanghai city is chosen as an example area for checking the improvements of the new method. The results show that the PS points extracted by the new method have high quality, high stability and meet the strong scattering characteristics. Based on these high quality PS points, the deformation rate along the line-of-sight (LOS) in the central urban area of Shanghai is obtained by using 35 COSMO-SkyMed X-band SAR images acquired from 2008 to 2010 and it varies from -14.6 mm/year to 4.9 mm/year. There is a large sedimentation funnel in the cross boundary of Hongkou and Yangpu district with a maximum sedimentation rate of more than 14 mm per year. The obtained ground subsidence rates are also compared with the result of spirit leveling and show good consistent. Our new method for PS point extraction is more reasonable, and can improve the accuracy of the obtained deformation results.

A phase I and pharmacologic trial of two schedules of the proteasome inhibitor, PS-341 (bortezomib, velcade), in patients with advanced cancer.

PubMed

Dy, Grace K; Thomas, James P; Wilding, George; Bruzek, Laura; Mandrekar, Sumithra; Erlichman, Charles; Alberti, Dona; Binger, Kim; Pitot, Henry C; Alberts, Steven R; Hanson, Lorelei J; Marnocha, Rebecca; Tutsch, Kendra; Kaufmann, Scott H; Adjei, Alex A

2005-05-01

To define the toxicities, pharmacodynamics, and clinical activity of the proteasome inhibitor, PS-341 (bortezomib), in patients with advanced malignancies. Twenty-eight patients (14 male and 14 female) received PS-341 twice weekly for 4 of 6 weeks (schedule I). Because toxicity necessitated dose omissions on this schedule, 16 additional patients (12 male and 4 female) received PS-341 twice weekly for 2 of every 3 weeks (schedule II). A total of 73 courses of treatment was given (median, 2; range, 1-4). Inhibition of 20S proteasome activity in peripheral blood mononuclear cells (PBMC) and accumulation of proteasome-targeted polypeptides in tumor tissue were evaluated as pharmacodynamic markers of PS-341 activity. The most common toxicity was thrombocytopenia, which was dose limiting at 1.7 mg/m2 (schedule I) and 1.6 mg/m2 (schedule II), respectively. Sensory neuropathy was dose-limiting in a patient in schedule I. Grade > or =3 toxicities for schedule I were constipation, fatigue, myalgia, and sensory neuropathy. Grade > or =3 toxicities for schedule II were dehydration resulting from diarrhea, nausea and vomiting, fatigue, hypoglycemia, and hypotension. The maximum tolerated dose was 1.5 mg/m2 for both schedules. Reversible dose-dependent decreases in 20S proteasome activity in PBMCs were observed, with 36% inhibition at 0.5 mg/m2, 52% at 0.9 mg/m2, and 75% at 1.25 mg/m2. Accumulation of proteasome-targeted polypeptides was detected in tumor samples after treatment with PS-341. A patient with multiple myeloma had a partial response. PS-341 given 1.5 mg/m2 twice weekly for 2 of every 3 weeks is well tolerated and should be further studied.

65Plus: open-label study of bevacizumab in combination with pemetrexed or pemetrexed/carboplatin as first-line treatment of patients with advanced or recurrent nonsquamous non-small-cell lung cancer.

PubMed

Schuette, Wolfgang; Schneider, Claus-Peter; Engel-Riedel, Walburga; Schumann, Christian; Kohlhaeufl, Martin; Serke, Monika Heidi Ursel; Hoeffken, Gert; Kortsik, Cornelius; Reck, Martin

2017-01-01

The aim of the study was to investigate in terms of noninferiority the efficacy and safety of a monochemotherapy regimen of pemetrexed plus bevacizumab (BevPem) versus carboplatin/pemetrexed plus bevacizumab (BevCPem) in elderly patients as first-line treatment for advanced metastatic or recurrent nonsquamous non-small-cell lung cancer (NSCLC). 65Plus was a Phase III, randomized, open-label study. In total, 253 patients received BevPem (n=119) or BevCPem (n=134). The primary outcome measure was progression-free survival. Secondary end points were overall survival, tumor response, and safety outcomes. Evaluations were performed for the whole study population and stratified according to Eastern Cooperative Oncology Group (ECOG) performance status (PS). Noninferiority of BevPem in comparison to BevCPem could not be demonstrated for the overall population ( P =0.7864). Significant superiority of the combined treatment BevCPem was seen in patients of ECOG PS 0-1 (median PFS 5.1 vs 6.9 months, HR 1.353, 95% CI 1.03-1.777), while the opposite tendency was observed in patients with ECOG PS 2 (median PFS 2.9 vs 1.5 months, HR 0.628, 95% CI 0.195-2.025). Overall, better tolerability was found for the BevPem group, irrespective of ECOG PS. Results from the 65plus study give evidence that BevPem and BevCPem treatments may exert differential effects on PFS, depending on the patients ECOG PS. It appears that patients with better ECOG PS (0-1) benefited more from the combined treatment with carboplatin, while the group comprising more severely impaired patients (ECOG PS 2) benefited more from the monochemotherapy.

Longitudinal DSC-MRI for Distinguishing Tumor Recurrence From Pseudoprogression in Patients With a High-grade Glioma.

PubMed

Boxerman, Jerrold L; Ellingson, Benjamin M; Jeyapalan, Suriya; Elinzano, Heinrich; Harris, Robert J; Rogg, Jeffrey M; Pope, Whitney B; Safran, Howard

2017-06-01

For patients with high-grade glioma on clinical trials it is important to accurately assess time of disease progression. However, differentiation between pseudoprogression (PsP) and progressive disease (PD) is unreliable with standard magnetic resonance imaging (MRI) techniques. Dynamic susceptibility contrast perfusion MRI (DSC-MRI) can measure relative cerebral blood volume (rCBV) and may help distinguish PsP from PD. A subset of patients with high-grade glioma on a phase II clinical trial with temozolomide, paclitaxel poliglumex, and concurrent radiation were assessed. Nine patients (3 grade III, 6 grade IV), with a total of 19 enhancing lesions demonstrating progressive enhancement (≥25% increase from nadir) on postchemoradiation conventional contrast-enhanced MRI, had serial DSC-MRI. Mean leakage-corrected rCBV within enhancing lesions was computed for all postchemoradiation time points. Of the 19 progressively enhancing lesions, 10 were classified as PsP and 9 as PD by biopsy/surgery or serial enhancement patterns during interval follow-up MRI. Mean rCBV at initial progressive enhancement did not differ significantly between PsP and PD (2.35 vs. 2.17; P=0.67). However, change in rCBV at first subsequent follow-up (-0.84 vs. 0.84; P=0.001) and the overall linear trend in rCBV after initial progressive enhancement (negative vs. positive slope; P=0.04) differed significantly between PsP and PD. Longitudinal trends in rCBV may be more useful than absolute rCBV in distinguishing PsP from PD in chemoradiation-treated high-grade gliomas with DSC-MRI. Further studies of DSC-MRI in high-grade glioma as a potential technique for distinguishing PsP from PD are indicated.

Phase-step retrieval for tunable phase-shifting algorithms

NASA Astrophysics Data System (ADS)

Ayubi, Gastón A.; Duarte, Ignacio; Perciante, César D.; Flores, Jorge L.; Ferrari, José A.

2017-12-01

Phase-shifting (PS) is a well-known technique for phase retrieval in interferometry, with applications in deflectometry and 3D-profiling, which requires a series of intensity measurements with certain phase-steps. Usually the phase-steps are evenly spaced, and its knowledge is crucial for the phase retrieval. In this work we present a method to extract the phase-step between consecutive interferograms. We test the proposed technique with images corrupted by additive noise. The results were compared with other known methods. We also present experimental results showing the performance of the method when spatial filters are applied to the interferograms and the effect that they have on their relative phase-steps.

ROS Hexapod

NASA Technical Reports Server (NTRS)

Davis, Kirsch; Bankieris, Derek

2016-01-01

As an intern project for NASA Johnson Space Center (JSC), my job was to familiarize myself and operate a Robotics Operating System (ROS). The project outcome will convert existing software assets into ROS using nodes, enabling a robotic Hexapod to communicate and to be functional and controlled by an existing PlayStation 3 (PS3) controller. Existing control algorithms and current libraries have no ROS capabilities within the Hexapod C++ source code. Conversion of C++ codes to ROS will enable existing code to be compatible with ROS, and will be controlled using existing PS3 controller. Furthermore, my job description is to design ROS messages and script programs which will enable assets to participate in the ROS ecosystem. In addition, an open source software (IDE) Arduino board will be integrated in the ecosystem with designing circuitry on a breadboard to add additional behavior with push buttons, potentiometers and other simple elements in the electrical circuitry. Other projects with the Arduino will be a GPS module digital clock that will run off 22 satellites to show accurate real time using a GPS signal and internal patch antenna to communicate with satellites.

Self-assembled photosystem-I biophotovoltaics on nanostructured TiO(2 )and ZnO.

PubMed

Mershin, Andreas; Matsumoto, Kazuya; Kaiser, Liselotte; Yu, Daoyong; Vaughn, Michael; Nazeeruddin, Md K; Bruce, Barry D; Graetzel, Michael; Zhang, Shuguang

2012-01-01

The abundant pigment-protein membrane complex photosystem-I (PS-I) is at the heart of the Earth's energy cycle. It is the central molecule in the "Z-scheme" of photosynthesis, converting sunlight into the chemical energy of life. Commandeering this intricately organized photosynthetic nanocircuitry and re-wiring it to produce electricity carries the promise of inexpensive and environmentally friendly solar power. We here report that dry PS-I stabilized by surfactant peptides functioned as both the light-harvester and charge separator in solar cells self-assembled on nanostructured semiconductors. Contrary to previous attempts at biophotovoltaics requiring elaborate surface chemistries, thin film deposition, and illumination concentrated into narrow wavelength ranges the devices described here are straightforward and inexpensive to fabricate and perform well under standard sunlight yielding open circuit photovoltage of 0.5 V, fill factor of 71%, electrical power density of 81 µW/cm(2) and photocurrent density of 362 µA/cm(2), over four orders of magnitude higher than any photosystem-based biophotovoltaic to date.

Self-assembled photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO

PubMed Central

Mershin, Andreas; Matsumoto, Kazuya; Kaiser, Liselotte; Yu, Daoyong; Vaughn, Michael; Nazeeruddin, Md. K.; Bruce, Barry D.; Graetzel, Michael; Zhang, Shuguang

2012-01-01

The abundant pigment-protein membrane complex photosystem-I (PS-I) is at the heart of the Earth’s energy cycle. It is the central molecule in the “Z-scheme” of photosynthesis, converting sunlight into the chemical energy of life. Commandeering this intricately organized photosynthetic nanocircuitry and re-wiring it to produce electricity carries the promise of inexpensive and environmentally friendly solar power. We here report that dry PS-I stabilized by surfactant peptides functioned as both the light-harvester and charge separator in solar cells self-assembled on nanostructured semiconductors. Contrary to previous attempts at biophotovoltaics requiring elaborate surface chemistries, thin film deposition, and illumination concentrated into narrow wavelength ranges the devices described here are straightforward and inexpensive to fabricate and perform well under standard sunlight yielding open circuit photovoltage of 0.5 V, fill factor of 71%, electrical power density of 81 µW/cm2 and photocurrent density of 362 µA/cm2, over four orders of magnitude higher than any photosystem-based biophotovoltaic to date. PMID:22355747

Cherenkov radiation conversion and collection considerations for a gamma bang time/reaction history diagnostic for the NIF.

PubMed

Herrmann, Hans W; Mack, Joseph M; Young, Carlton S; Malone, Robert M; Stoeffl, Wolfgang; Horsfield, Colin J

2008-10-01

Bang time and reaction history measurements are fundamental components of diagnosing inertial confinement fusion (ICF) implosions and will be essential contributors to diagnosing attempts at ignition on the National Ignition Facility (NIF). Fusion gammas provide a direct measure of fusion interaction rate without being compromised by Doppler spreading. Gamma-based gas Cherenkov detectors that convert fusion gamma rays to optical Cherenkov photons for collection by fast recording systems have been developed and fielded at Omega. These systems have established their usefulness in illuminating ICF physics in several experimental campaigns. Bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF system design requirements. A comprehensive, validated numerical study of candidate systems is providing essential information needed to make a down selection based on optimization of sensitivity, bandwidth, dynamic range, cost, and NIF logistics. This paper presents basic design considerations arising from the two-step conversion process from gamma rays to relativistic electrons to UV/visible Cherenkov radiation.

Picosecond imaging of inertial confinement fusion plasmas using electron pulse-dilation

NASA Astrophysics Data System (ADS)

Hilsabeck, T. J.; Nagel, S. R.; Hares, J. D.; Kilkenny, J. D.; Bell, P. M.; Bradley, D. K.; Dymoke-Bradshaw, A. K. L.; Piston, K.; Chung, T. M.

2017-02-01

Laser driven inertial confinement fusion (ICF) plasmas typically have burn durations on the order of 100 ps. Time resolved imaging of the x-ray self emission during the hot spot formation is an important diagnostic tool which gives information on implosion symmetry, transient features and stagnation time. Traditional x-ray gated imagers for ICF use microchannel plate detectors to obtain gate widths of 40-100 ps. The development of electron pulse-dilation imaging has enabled a 10X improvement in temporal resolution over legacy instruments. In this technique, the incoming x-ray image is converted to electrons at a photocathode. The electrons are accelerated with a time-varying potential that leads to temporal expansion as the electron signal transits the tube. This expanded signal is recorded with a gated detector and the effective temporal resolution of the composite system can be as low as several picoseconds. An instrument based on this principle, known as the Dilation X-ray Imager (DIXI) has been constructed and fielded at the National Ignition Facility. Design features and experimental results from DIXI will be presented.

Phytoplankton response to polystyrene microplastics: Perspective from an entire growth period.

PubMed

Mao, Yufeng; Ai, Hainan; Chen, Yi; Zhang, Zhenyu; Zeng, Peng; Kang, Li; Li, Wei; Gu, Weikang; He, Qiang; Li, Hong

2018-05-29

Microplastics are widely identified in aquatic environments, but their impacts on phytoplankton have not been extensively studied. Here, the responses of Chlorella pyrenoidosa under polystyrene (PS) microplastics exposure were studied across its whole growth period, with microplastic sizes of 0.1 and 1.0 μm and 3 concentration gradients each, which covered (10 and 50 mg/L) and exceeded (100 mg/L) its environmental concentrations, respectively. PS microplastics caused dose-dependent adverse effects on Chlorella pyrenoidosa growth from the lag to the earlier logarithmic phases, but exhibited slight difference in the maximal inhibition ratio (approximately 38%) with respect to the two microplastic sizes. In addition to the reduced photosynthetic activity of Chlorella pyrenoidosa, unclear pyrenoids, distorted thylakoids and damaged cell membrane were observed, attributing to the physical damage and oxidative stress caused by microplastics. However, from the end of the logarithmic to the stationary phase, Chlorella pyrenoidosa could reduce the adverse effects of microplastics jointly through cell wall thickening, algae homo-aggregation and algae-microplastics hetero-aggregation, hence triggering an increase of algal photosynthetic activity and its growth, and cell structures turned to normal. Our study confirmed that PS microplastics can impair but then enhance algae growth, which will be helpful in understanding the ecological risks of microplastics. Copyright © 2018 Elsevier Ltd. All rights reserved.

Relaxation dynamics of femtosecond-laser-induced temperature modulation on the surfaces of metals and semiconductors

NASA Astrophysics Data System (ADS)

Levy, Yoann; Derrien, Thibault J.-Y.; Bulgakova, Nadezhda M.; Gurevich, Evgeny L.; Mocek, Tomáš

2016-06-01

Formation of laser-induced periodic surface structures (LIPSS) is a complicated phenomenon which involves periodic spatial modulation of laser energy absorption on the irradiated surface, transient changes in optical response, surface layer melting and/or ablation. The listed processes strongly depend on laser fluence and pulse duration as well as on material properties. This paper is aimed at studying the spatiotemporal evolution of a periodic modulation of the deposited laser energy, once formed upon irradiation of metal (Ti) and semiconductor (Si) surfaces. Assuming that the incoming laser pulse interferes with a surface electromagnetic wave, the resulting sinusoidal modulation of the absorbed laser energy is introduced into a two-dimensional two-temperature model developed for titanium and silicon. Simulations reveal that the lattice temperature modulation on the surfaces of both materials following from the modulated absorption remains significant for longer than 50 ps after the laser pulse. In the cases considered here, the partially molten phase exists 10 ps in Ti and more than 50 ps in Si, suggesting that molten matter can be subjected to temperature-driven relocation toward LIPSS formation, due to the modulated temperature profile on the material surfaces. Molten phase at nanometric distances (nano-melting) is also revealed.

Low-voltage operating flexible ferroelectric organic field-effect transistor nonvolatile memory with a vertical phase separation P(VDF-TrFE-CTFE)/PS dielectric

NASA Astrophysics Data System (ADS)

Xu, Meili; Xiang, Lanyi; Xu, Ting; Wang, Wei; Xie, Wenfa; Zhou, Dayu

2017-10-01

Future flexible electronic systems require memory devices combining low-power operation and mechanical bendability. However, high programming/erasing voltages, which are universally needed to switch the storage states in previously reported ferroelectric organic field-effect transistor (Fe-OFET) nonvolatile memories (NVMs), severely prevent their practical applications. In this work, we develop a route to achieve a low-voltage operating flexible Fe-OFET NVM. Utilizing vertical phase separation, an ultrathin self-organized poly(styrene) (PS) buffering layer covers the surface of the ferroelectric polymer layer by one-step spin-coating from their blending solution. The ferroelectric polymer with a low coercive field contributes to low-voltage operation in the Fe-OFET NVM. The polymer PS contributes to the improvement of mobility, attributing to screening the charge scattering and decreasing the surface roughness. As a result, a high performance flexible Fe-OFET NVM is achieved at the low P/E voltages of ±10 V, with a mobility larger than 0.2 cm2 V-1 s-1, a reliable P/E endurance over 150 cycles, stable data storage retention capability over 104 s, and excellent mechanical bending durability with a slight performance degradation after 1000 repetitive tensile bending cycles at a curvature radius of 5.5 mm.

Analytical approaches to optimizing system "Semiconductor converter-electric drive complex"

NASA Astrophysics Data System (ADS)

Kormilicin, N. V.; Zhuravlev, A. M.; Khayatov, E. S.

2018-03-01

In the electric drives of the machine-building industry, the problem of optimizing the drive in terms of mass-size indicators is acute. The article offers analytical methods that ensure the minimization of the mass of a multiphase semiconductor converter. In multiphase electric drives, the form of the phase current at which the best possible use of the "semiconductor converter-electric drive complex" for active materials is different from the sinusoidal form. It is shown that under certain restrictions on the phase current form, it is possible to obtain an analytical solution. In particular, if one assumes the shape of the phase current to be rectangular, the optimal shape of the control actions will depend on the width of the interpolar gap. In the general case, the proposed algorithm can be used to solve the problem under consideration by numerical methods.

InAs nanowires grown by metal-organic vapor-phase epitaxy (MOVPE) employing PS/PMMA diblock copolymer nanopatterning.

PubMed

Huang, Yinggang; Kim, Tae Wan; Xiong, Shisheng; Mawst, Luke J; Kuech, Thomas F; Nealey, Paul F; Dai, Yushuai; Wang, Zihao; Guo, Wei; Forbes, David; Hubbard, Seth M; Nesnidal, Michael

2013-01-01

Dense arrays of indium arsenide (InAs) nanowire materials have been grown by selective-area metal-organic vapor-phase epitaxy (SA-MOVPE) using polystyrene-b-poly(methyl methacrylate) (PS/PMMA) diblock copolymer (DBC) nanopatterning technique, which is a catalyst-free approach. Nanoscale openings were defined in a thin (~10 nm) SiNx layer deposited on a (111)B-oriented GaAs substrate using the DBC process and CF4 reactive ion etching (RIE), which served as a hard mask for the nanowire growth. InAs nanowires with diameters down to ~ 20 nm and micrometer-scale lengths were achieved with a density of ~ 5 × 10(10) cm(2). The nanowire structures were characterized by scanning electron microscopy and transmission electron microscopy, which indicate twin defects in a primary zincblende crystal structure and the absence of threading dislocation within the imaged regions.

Stable fiber-optic time transfer by active radio frequency phase locking.

PubMed

Yin, Feifei; Wu, Zhongle; Dai, Yitang; Ren, Tianpeng; Xu, Kun; Lin, Jintong; Tang, Geshi

2014-05-15

In this Letter we demonstrate a fiber link capable of stable time signal transfer utilizing our active long-distance radio frequency (RF) stabilization technology. Taking advantage of the chromatic dispersion in optical fiber, our scheme compensates dynamically the link delay variation by tuning the optical carrier wavelength to phase lock a round-trip RF reference. Since the time signal and the RF reference are carried by the same optical carrier, a highly stable time transfer is achieved at the same time. Experimentally, we demonstrate a stability of the time signal transfer over 50-km fiber with a time deviation of 40 ps at 1-s average and 2.3 ps at 1000-s average. The performance of the RF reference delivery is also tested, with an Allan deviation of 2×10(-15) at 1000-s average. According to our proposal, a simultaneous stable time and frequency transfer is expected.

Atomic-deficient nanostructurization in water-sorption alumomagnesium spinel ceramics MgAl2O4

NASA Astrophysics Data System (ADS)

Ingram, A.

2018-02-01

Atomic-deficient nanostructurization in alumomagnesium MgAl2O4 ceramics sintered at 1100-1400 °C caused by water sorption are studied employing positron annihilation lifetime spectroscopy. Detected PAL spectra are reconstructed from unconstrained x4-term decomposition, and further transformed to x3-term form to be applicable for analysis with x3-x2-CDA (coupling decomposition algorithm). It is proved that water-immersion processes reduce positronium (Ps) decaying in large-size holes of ceramics (1.70-1.84 nm in radius) at the expense of enhanced trapping in tiny ( 0.2 nm in radius) Ps-traps. The water sorption is shown to be more pronounced in structurally imperfect ceramics sintered at T s = 1100-1200 °C due to irreversible transformations between constituting phases, while reversible physical-sorption processes are dominated in structurally uniform ceramics composed of main spinel phase.

Heterogeneous nucleation and growth dynamics in the light-induced phase transition in vanadium dioxide

DOE PAGES

Brady, Nathaniel F.; Appavoo, Kannatassen; Seo, Minah; ...

2016-03-02

Here we report on ultrafast optical investigations of the light-induced insulator-to-metal phase transition in vanadium dioxide with controlled disorder generated by substrate mismatch. These results reveal common dynamics of this optically-induced phase transition that are independent of this disorder. Lastly, above the fluence threshold for completing the transition to the rutile crystalline phase, we find a common time scale, independent of sample morphology, of 40.5 ± 2 ps that is consistent with nucleation and growth dynamics of the R phase from the parent M1 ground state.

Convertible MRI contrast: Sensing the delivery and release of anti-glioma nano-drugs

NASA Astrophysics Data System (ADS)

Zhang, Liang; Zhang, Zhongwei; Mason, Ralph P.; Sarkaria, Jann N.; Zhao, Dawen

2015-05-01

There is considerable interest in developing nanohybrids of imaging contrast agents and drugs for image-guided drug delivery. We have developed a strategy of utilizing manganese (Mn) to enhance the nano-encapsulation of arsenic trioxide (ATO). Formation of arsenite (As3+)-Mn precipitates in liposomes generates magnetic susceptibility effects, reflected as dark contrast on T2-weighted MRI. Intriguingly, following cell uptake, the As-Mn complex decomposes in response to low pH in endosome-lysosome releasing ionic As3+, the active form of ATO, and Mn2+, the T1 contrast agent that gives a bright signal. Glioblastoma (GBM) is well known for its high resistance to chemotherapy, e.g., temozolomide (TMZ). Building upon the previously established phosphatidylserine (PS)-targeted nanoplatform that has excellent GBM-targeting specificity, we now demonstrate the effectiveness of the targeted nanoformulated ATO for treating TMZ-resistant GBM cells and the ability of the convertible Mn contrast as a surrogate revealing the delivery and release of ATO.

A facile synthesis of dynamic, shape-changing polymer particles.

PubMed

Klinger, Daniel; Wang, Cynthia X; Connal, Luke A; Audus, Debra J; Jang, Se Gyu; Kraemer, Stephan; Killops, Kato L; Fredrickson, Glenn H; Kramer, Edward J; Hawker, Craig J

2014-07-01

We herein report a new facile strategy to ellipsoidal block copolymer nanoparticles that exhibit a pH-triggered anistropic swelling profile. In a first step, elongated particles with an axially stacked lamellae structure are selectively prepared by utilizing functional surfactants to control the phase separation of symmetric polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) in dispersed droplets. In a second step, the dynamic shape change is realized by cross-linking the P2VP domains, thereby connecting glassy PS discs with pH-sensitive hydrogel actuators. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Glufosinate ammonium clean-up procedure from water samples using SPE

NASA Astrophysics Data System (ADS)

Tayeb M., A.; Ismail B., S.; Mardiana-Jansar, K.; Ta, Goh Choo; Agustar, Hani Kartini

2015-09-01

For the determination of glufosinate ammonium residue in soil and water samples, different solid phase extraction (SPE) sorbent efficiency was studied. Four different SPE sorbents i.e.: CROMABOND PS-H+, CROMABOND PS-OH-, ISOLUTE ENV+, Water Sep-Pak and OASIS HLB were used. Sample clean-up performance was evaluated using high performance liquid chromatography (Agilent 1220 infinity LC) with fluorescence detector. Detection of FMO-derivatives was done at λ ex = 260 nm and λ em= 310 nm. OASIS HLB column was the most suitable for the clean-up in view of the overall feasibility of the analysis.

Findings in Ps-H scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ray, Hasi

2006-06-15

The best three-channel projectile-inelastic close-coupling approximation (CCA) is used to study the resonances in positronium (Ps) and hydrogen (H) scattering at the energy region below the inelastic threshold. The s-wave elastic phase shifts and s-wave elastic cross sections are studied using the static-exchange, two- and three-channel projectile-inelastic CCA for both the singlet (+) and triplet (-) channels. The singlet resonances detected using different CCA schemes confirm previous predictions [Drachman and Houston, Phys. Rev. A 12, 885 (1975); Page, J. Phys. B. 9, 1111 (1976)]. We report a resonance in the triplet channel too using the present three-channel CCA scheme.

Command Flight Path Display. Phase I and II.

DTIC Science & Technology

1983-09-01

transmissions over the standard 56K baud interface. The PS-300 was a commercial unit and required some modifications to ensure its reliability in an...1 H7750-AA Battery Backup NADC 5 Oct E2 9 1 LA-12D Decwriter SAI/RtS 4 11ov 82 10 1 BC03M-25 Null Modem Cable SAI/RM0S 4 Nov 82 35 2 ~%*~’ .5°’ 11 1...of about 1200 baud. (The interface hardware is capable of 56K baud transmission, but the standard PS-300 firmware is only able to process input

A Standalone Solar Photovoltaic Power Generation using Cuk Converter and Single Phase Inverter

NASA Astrophysics Data System (ADS)

Verma, A. K.; Singh, B.; Kaushika, S. C.

2013-03-01

In this paper, a standalone solar photovoltaic (SPV) power generating system is designed and modeled using a Cuk dc-dc converter and a single phase voltage source inverter (VSI). In this system, a dc-dc boost converter boosts a low voltage of a PV array to charge a battery at 24 V using a maximum power point tracking control algorithm. To step up a 24 V battery voltage to 360 V dc, a high frequency transformer based isolated dc-dc Cuk converter is used to reduce size, weight and losses. The dc voltage of 360 V is fed to a single phase VSI with unipolar switching to achieve a 230 Vrms, 50 Hz ac. The main objectives of this investigation are on efficiency improvement, reduction in cost, weight and size of the system and to provide an uninterruptible power to remotely located consumers. The complete SPV system is designed and it is modeled in MATLAB/Simulink. The simulated results are presented to demonstrate its satisfactory performance for validating the proposed design and control algorithm.

Picosecond pulsed electric fields induce apoptosis in HeLa cells via the endoplasmic reticulum stress and caspase-dependent signaling pathways.

PubMed

Chen, Wen-Juan; Xiong, Zheng-Ai; Zhang, Min; Yao, Chen-Guo; Zhao, Zhong-Yong; Hua, Yuan-Yuan; Zhou, Wei

2013-03-01

The non-invasive treatment of tumors with preserved fertility holds great promise. The application of pulsed electric field (PEF) is a new biomedical engineering technique for tumor therapy. Picosecond pulsed electric fields (psPEF) can be transferred to target deep tissue non-invasively and precisely; however, research of the biological effects of psPEF on cells is limited. Electric theory predicts that when the pulse duration decreases to nanoseconds and picoseconds, it will mainly affect organelles and lead to intracellular electromanipulations. Previous studies have shown that psPEF targets the mitochondria and induces apoptosis through a mitochondrial-mediated pathway in HeLa cells. The endoplasmic reticulum is also involved in the intrinsic pathways of apoptosis. In the present study, HeLa cells were exposed to psPEF to investigate the underlying mechanisms of apoptosis. MTT assay demonstrated that psPEF displayed strong growth inhibitory effects on HeLa cells. Treatment with psPEF led to marked cell apoptosis and cell cycle arrest at the G2/M phase. In addition, psPEF affected the phosphorylation levels of endoplasmic reticulum sensors and upregulated the expression of glucose-regulated protein 78 (GRP78), glucose-regulated protein 94 (GRP94) and CCAAT enhancer-binding protein (C/EBP) homologous protein (CHOP). These changes were accompanied by the elevation of intracellular Ca2+ concentrations. Furthermore, the activation of caspase-12, -9 and -3, led to the release of cytochrome c, as well as the upregulation of Bax and the downregulation of Bcl-2, as observed in the HeLa cells. Taken together, these data suggest that psPEF is an efficient apoptosis-inducing agent for HeLa cells, which exerts its effects, at least partially, via the endoplasmic reticulum stress and caspase-dependent signaling pathways.

Ternary blend polymer solar cells with self-assembled structure for enhancing power conversion efficiency

NASA Astrophysics Data System (ADS)

Yang, Zhenhua; Li, Hongfei; Nam, Chang-Yong; Kisslinger, Kim; Satija, Sushil; Rafailovich, Miriam

Bulk heterojunction (BHJ) polymer solar cells are an area of intense interest due to their advantages such as mechanical flexibility. The active layer is typically spin coated from the solution of polythiophene derivatives (donor) and fullerenes (acceptor) and interconnected domains are formed because of phase separation. However, the power conversion efficiency (PCE) of BHJ solar cell is restricted by the disordered inner structures in the active layer, donor or acceptor domains isolated from electrodes. Here we report a self-assembled columnar structure formed by phase separation between (PCDTBT) and polystyrene (PS) for the active layer morphology optimization. The BHJ solar cell device based on this structure is promising for exhibiting higher performance due to the shorter carrier transportation pathway and larger interfacial area between donor and acceptor. The surface morphology is investigated with atomic force microscopy (AFM) and the columnar structure is studied by investigation of cross-section of the blend thin film of PCDTBT and PS under the transmission electron microscopy (TEM). The different morphological structures formed via phase segregation are correlated with the performance of the BHJ solar cells.